Inkjet printer

Abstract

The invention provides an ink jet printer. The inkjet printer suppresses the occurrence of drawing failures. The inkjet printer includes: a nozzle configured to eject ink toward a drawing target object; a storage unit that stores drawing data specifying an ejection timing of the nozzle at each of a plurality of offset positions in the transport direction, the ejection timing corresponding to the drawing information; an optical movement measurement sensor receiving light from the drawing target object and generating a measurement value related to movement of the drawing target object in the transport direction based on the received light; and a drawing control unit that controls ink ejection from the nozzle on the basis of the drawing data and a current offset position of the measurement value generated by the optical movement measurement sensor with respect to a reference position, in accordance with reference position information indicating that the reference position of the drawing target object is at a predetermined position.

Description

Technical Field

[0001] The present invention relates to an inkjet printer for drawing information by causing ejected ink to adhere to an object. Background Art

[0002] For example, characters, symbols, images, etc. indicating various types of information such as dates, serial numbers, and barcodes are drawn on packaging materials such as corrugated cardboard. JP2014-144574A discloses a drop-on-demand (DOD) type inkjet printer that performs printing by ejecting ink onto packaging materials.

[0003] In the inkjet printer, ink supplied from an ink tank is ejected from an ejection port formed in a nozzle, forms ink particles, flies to the surface of a packaging material, and then lands on the surface, thereby drawing characters or the like.

[0004] Meanwhile, the drawing accuracy of the inkjet printer is determined based on the relative moving speed of the drawing target relative to the nozzle and the distance between the drawing target and the nozzle. However, at the place where the drawing target is conveyed, changes in the conveying line speed and changes in the position of the drawing target conveyed by the conveying line in the line width direction occur, and in principle, errors caused by the sliding of the drawing target on the conveying line also occur. If the above changes and errors exceed the preset landing accuracy tolerance, a drawing failure results. Summary of the invention

[0005] The present invention has been made in view of such a viewpoint, and an object thereof is to suppress the occurrence of rendering failure.

[0006] In order to achieve the above-mentioned object, according to one embodiment of the present invention, an inkjet printer can be designed, which ejects ink to draw information on an object conveyed by a conveyor. For example, the inkjet printer may include: an ink tank that stores ink; a nozzle that is configured to eject ink supplied from the ink tank toward a drawing target object; a storage unit that stores drawing data specifying the ejection timing of the nozzle at each of a plurality of offset positions in a conveying direction, the ejection timing corresponding to the drawing information; an optical movement measurement sensor that receives light from the drawing target object and generates a measurement value related to the movement of the drawing target object in the conveying direction based on the received light; and a drawing control unit that controls the ejection of ink from the nozzle based on reference position information indicating that the reference position of the drawing target object is at a predetermined position, a current offset position relative to the reference position based on the measurement value generated by the optical movement measurement sensor, and the drawing data.

[0007] According to this configuration, information such as characters including numbers, symbols, bar codes, two-dimensional codes, and images can be drawn on an object conveyed by a conveyor. At this time, a measurement value related to the movement of the drawing target object in the conveying direction is generated by an optical movement measurement sensor. Based on the measurement value and the reference position information of the object, the current offset position relative to the reference position of the object can be acquired. When the ink ejection from the nozzle is controlled based on the acquired current offset position and the drawing data stored in the storage unit, the influence of errors caused by changes in the conveying line speed and the sliding of the drawing target object is suppressed, thereby suppressing the occurrence of drawing failure. The drawing includes, for example, the printing of characters, the printing of codes and images, etc.

[0008] The reference position information may be a timing signal indicating that the drawing target object conveyed by the conveyor has reached a predetermined position. In this case, a timing signal output unit for outputting a timing signal is further included, and the drawing control unit may obtain the timing signal output from the timing signal output unit as the reference position information.

[0009] In addition, the optical movement measuring sensor may also generate a timing signal indicating that the drawing target object has reached a predetermined position based on a change in the amount of received light. In this case, the drawing control unit may acquire the timing signal generated by the optical movement measuring sensor as the reference position information.

[0010] The optical movement measuring sensor may include: a light projecting unit that projects light onto a drawing target object; and a light receiving unit that receives a speckle pattern generated by the light projected from the light projecting unit according to characteristics of a surface shape of the drawing target object, and generates light reception data including the speckle pattern. In this case, a measurement value related to the movement of the drawing target object in the conveying direction may be generated with high accuracy based on the movement amount of the speckle pattern generated by the light receiving unit.

[0011] A movement amount acquisition unit that acquires a movement amount caused by the conveyor may also be included. In this case, when the accuracy of the measurement value generated by the optical movement measurement sensor is less than a predetermined value, the drawing control unit may control the ink ejection from the nozzle based on the movement amount acquired by the movement amount acquisition unit and the drawing data. That is, when the accuracy of the measurement value is low, the drawing accuracy may be improved by controlling the ink ejection from the nozzle based on the current offset position and the drawing data.

[0012] In addition, the drawing control unit may determine whether the measurement value generated by the optical movement measurement sensor exceeds a threshold value, and may control the ejection of ink from the nozzle based on the movement amount acquired by the movement amount acquisition unit and the drawing data until the measurement value exceeds the threshold value. On the other hand, when the measurement value generated by the optical movement measurement sensor exceeds the threshold value, it may be estimated that the measurement value is inaccurate. Therefore, in this case, the drawing accuracy may be improved by controlling the ejection of ink from the nozzle based on the current offset position and the drawing data.

[0013] The optical movement measuring sensor can also measure the amount of movement of the drawing target object in a direction perpendicular to the moving direction. In this case, the drawing control unit controls the ejection of ink from the nozzle based on the amount of movement in the direction perpendicular to the moving direction measured by the optical movement measuring sensor, so that the vibration (bumping) of the drawing target object in the up and down directions can be corrected and the drawing accuracy can be improved.

[0014] The inkjet printer may further include a conveying direction recognition unit that recognizes the conveying direction. In this case, the drawing control unit may control the ejection of ink from the nozzle based on the conveying direction recognized by the conveying direction recognition unit. For example, the inkjet printer is configured such that the hydraulic head pressure of the liquid level of the ink stored in the ink tank is applied to the nozzle as a negative pressure so that the liquid level is within a predetermined inclination range relative to the horizontal plane. On the other hand, the conveying direction of the conveyor is inclined in some cases, and when the conveying direction recognized by the conveying direction recognition unit is inclined relative to the horizontal plane, the drawing control unit controls the ejection of ink from the nozzle to draw information parallel to the conveying direction, so that drawing can be performed similarly to the case where the drawing target object is conveyed horizontally.

[0015] As described above, the ejection of ink from the nozzle is controlled based on the reference position information indicating that the reference position of the drawing target object is at a predetermined position, the current offset position relative to the reference position based on the measurement value generated by the optical movement measurement sensor, and the drawing data stored in the storage unit, so that the occurrence of drawing failure can be suppressed. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a view showing the overall configuration of an inkjet printer according to an embodiment of the present invention;

[0017] Figure 2 is a block diagram of an inkjet printer;

[0018] Figure 3 is a perspective view showing an inkjet printer during operation;

[0019] Figure 4 is a diagram showing the ink passage of a plotter;

[0020] Figure 5 is a view schematically showing an example of plotting data;

[0021] Figure 6 is a perspective view of a plotter with a sensor unit fixed thereto;

[0022] Figure 7 is corresponding to Figure 6 , which shows another fixing example of the sensor unit;

[0023] Fig. 8A is a flowchart showing an example of a process of drawing settings;

[0024] Figure 8B is a flowchart showing an example of a processing procedure in installation assistance mode;

[0025] Figure 8C is a view showing an example of a display screen when the installation assistance mode is executed;

[0026] Fig.8D is a view showing an example of a detailed display screen;

[0027] Fig. 8E This is a view for explaining a case where a workpiece is conveyed at an angle.

[0028] Fig.8F is a view showing an example of a first corrected image;

[0029] Figure 8G is a view showing an example of a correction value input screen;

[0030] Figure 8H is a view showing an example of a second corrected image;

[0031] Fig. 9 is a flowchart showing an example of drawing control based only on detection speed or distance;

[0032] Fig.10 is a timing diagram showing the temporal relationship of ink ejection in a constant speed drawing setting;

[0033] Fig.11 is a timing diagram showing the temporal relationship of ink ejection at a non-constant speed;

[0034] Fig.12 is a flowchart showing an example of control when the detection accuracy decreases;

[0035] Fig.13 is a flowchart showing an example of control when the detection speed exceeds a threshold value;

[0036] Fig.14is a flowchart showing an example of control of bumping correction;

[0037] Fig.15 is a view used to describe the case where the plotted data is offset by bump correction;

[0038] Fig.16 is a flowchart showing an example of control including pitch correction of the rotation direction;

[0039] Fig.17 is a view showing a first example in a case where two optical movement measuring sensors are provided;

[0040] Fig.18 is a view showing a second example in the case where two optical movement measuring sensors are provided;

[0041] Fig.19 is a flowchart showing an example of inclined line handling control;

[0042] Fig. 20 is a flowchart showing an example of a process for acquiring an inclination angle of a workpiece relative to a plotter when the plotter is installed;

[0043] Fig.21 is a flowchart showing an example of a processing procedure in a case where the tilt angle of a workpiece during conveyance exceeds a permissible value;

[0044] Fig. 22 is a view showing a third example in the case where two optical movement measuring sensors are provided;

[0045] Fig.23 is a view showing a fourth example in the case where two optical movement measuring sensors are provided;

[0046] Fig.24 is a plan view showing the inkjet printer during operation;

[0047] Fig.25 is provided with two optical movement measuring sensors corresponding to Fig.24 's view;

[0048] Fig.26 is a perspective view of a sensor unit including two optical movement measuring sensors;

[0049] Fig. 27 is a view showing an internal structure of a sensor unit including two optical movement measuring sensors;

[0050] Fig.28 is a front view of a sensor unit including two optical movement measuring sensors;

[0051] Fig.29 is a view showing an internal structure in a case where a sensor unit including two optical movement measuring sensors is inverted;

[0052] Fig.30 is a perspective view of a sensor unit including two optical movement measuring sensors in an inverted state;

[0053] Fig.31 is a view showing an example in which a sensor is accommodated in a main housing;

[0054] Fig.32 is a view showing an example in which a sensor housing is installed at a position different from that of a main housing;

[0055] Fig.33 is a plan view showing an example of a pressing mechanism including a print head;

[0056] Fig.34 is a flowchart showing an example of control in a case where an optical movement measuring sensor is used as a timing sensor;

[0057] Fig.35 This is a view showing the exception handling settings screen;

[0058] Fig.36 is a view showing a first warning screen;

[0059] Fig.37 is a view showing a second warning screen;

[0060] Fig.38 is a flowchart representing an example of exception handling;

[0061] Fig.39 is a flowchart showing an example of abnormal processing when distance measurement is performed;

[0062] Fig.40 is a flow chart illustrating an example of a process for evaluating the reliability of sensor values;

[0063] Fig.41 is a flowchart showing an example of control including a drawing interruption process as an exception process;

[0064] Fig.42 is a flowchart showing an example of control for executing a drawing interruption process based on a result of distance measurement;

[0065] Fig.43 is a flowchart showing an example of control for notifying a distance abnormality based on a result of distance measurement;

[0066] Fig.44is a flowchart showing an example of control for notifying a distance abnormality and continuing drawing;

[0067] Fig.45 is a flowchart showing an example of control for disabling a draw start trigger in the case of a distance abnormality;

[0068] Fig.46 It is the timing diagram of the input of the timing sensor and the execution drawn;

[0069] Fig.47 is a flowchart showing an example of log file storage processing during a drawing period;

[0070] Fig.48 It is a view showing the drawing result confirmation screen;

[0071] Fig.49 is a view showing a screen for displaying time series data;

[0072] Fig.50 is corresponding to Figure 3 , which shows an example of using the inspection device during operation;

[0073] Fig.51 It is a block diagram of the inspection device;

[0074] Fig.52 is a view showing an image display confirmation window;

[0075] Fig.53 is a view showing an image display window for displaying an inspection image;

[0076] Fig.54 is a flowchart showing an example of processing in the case where a pass / fail determination is performed using the measurement results of the conveyance speed and distance of a workpiece;

[0077] Fig.55 is a flowchart showing an example of a check process after the drawing process ends;

[0078] Fig.56 is a flowchart showing an example of processing in the case where a pass / fail determination is performed using the measurement results of the movement and distance perpendicular to the conveyance direction of the workpiece;

[0079] Fig.57 is a flowchart showing an example of an inspection process using a measurement result of a movement and a distance perpendicular to a conveyance direction of a workpiece;

[0080] Fig.58 is a view showing an installation example in the case where a plurality of distance sensors are provided;

[0081] Fig.59is a flowchart showing an example of an inspection process in a case where a plurality of distance sensors are provided to perform pass / fail determination; and

[0082] Fig.60 is a flowchart showing an example of the inspection process in a case where a plurality of distance sensors are provided. DETAILED DESCRIPTION

[0083] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be noted that the following preferred embodiments are described only as examples in nature and are not intended to limit the present invention, its application, or its uses.

[0084] Figure 1 1 is a diagram showing the overall structure of an inkjet printer 1 according to an embodiment of the present invention. Figure 2 : is a block diagram of an inkjet printer 1. The inkjet printer 1 includes, for example, a plotter 2, a sensor unit 3, a controller 4, and an operation terminal 5. The plotter 2 is a part that performs a drawing process on a drawing target object, and is configured separately from the controller 4. The sensor unit 3 is a part that performs measurements required for the plotter 2 to perform a drawing process and measurements required for a drawing check, and is configured separately from the controller 4. The controller 4 is a part that controls the plotter 2 and the sensor unit 3, and may also be referred to as a control device, a control unit, etc. The operation terminal 5 includes a personal computer, etc., and is a part that allows a user to perform, for example, input of drawing information, various settings, selection, confirmation, etc. The operation terminal 5 includes, for example: a terminal-side display unit 5a including a liquid crystal display, etc.; and a terminal-side operation unit 5b including a keyboard, a mouse, a pointing device, etc.

[0085] The above configuration examples are examples, and the present invention is not limited to the above configuration examples. That is, the controller 4 may be incorporated in the operation terminal 5, or may be incorporated in the plotter 2. In addition, the operation terminal 5 may be used as the controller 4. In addition, Figure 1 and Figure 2 An external device 6 including a programmable logic controller (PLC) or the like is shown and is communicatively connected to the controller 4. A control signal output from the external device 6 is input to the controller 4. The external device 6 may be a device constituting a part of the inkjet printer 1, or may be a device separate from the inkjet printer 1.

[0086] Figure 1 and Figure 2 The encoder 7 and the timing sensor 8 are shown. The encoder 7 is used to obtain the timing information to be described later. Figure 3The moving amount acquiring unit may be configured to acquire information about the moving amount of the conveyor 10 shown. Examples of the information about the moving amount may include a pulse signal, and the moving amount may be calculated by the number of such pulse signals. The timing sensor 8 is a sensor configured to detect that the drawing target object conveyed by the conveyor 10 has reached a predetermined position, and may generally include a photoelectric sensor, a mark sensor, a distance sensor, etc.

[0087] One or both of the encoder 7 and the timing sensor 8 are provided. The encoder 7 and the timing sensor 8 may be devices each constituting a part of the inkjet printer 1, or may be devices separate from the inkjet printer 1.

[0088] like Figure 3 As shown, the inkjet printer 1 is a device configured to draw various types of information on a workpiece W (an example of a drawing target object) conveyed by a conveyor 10, and is an online device used by being incorporated in a manufacturing line (also referred to as a production line). The conveyor 10 is, for example, a belt conveyor, a roller conveyor, etc. The conveyor 10 constitutes a production line. The production line is installed in various factories, warehouses, etc.

[0089] The plotter 2 is fixed so that the relative position with respect to the conveyor 10 has a predetermined positional relationship. The member, device, tool, etc. for fixing the plotter 2 is not particularly limited, and examples thereof may include a fixing member 11 such as a fixing base or a bracket. The fixing member 11 may be fixed to a floor surface of a factory, a warehouse, etc., or may be fixed to a frame of the conveyor 10, etc.

[0090] During the operation of the inkjet printer 1, a plurality of workpieces W are placed on the conveying surface 10a of the conveyor 10 and are moved along the conveyor 10. Figure 3 The upstream side in the conveying direction is Figure 3 The downstream side in the conveying direction is Figure 3 . A plurality of workpieces W are placed on the conveying surface 10a in a state of being spaced apart from each other in the direction of arrow A as the conveying direction. The direction orthogonal to the direction of arrow A and along the conveying surface 10a is defined as the width direction. The conveying surface 10a may be horizontal, or may be inclined so as to have a predetermined angle relative to the horizontal plane, and therefore, the direction of arrow A is not always a horizontal direction.

[0091] Not all of the plurality of workpieces W are placed at the same position in the width direction of the conveying surface 10a, and the placement positions of the workpieces W on the conveying surface 10a may deviate from each other in the width direction of the conveying surface 10a. In addition, the workpieces W are conveyed by the friction force acting between the workpieces W and the conveying surface 10a, and therefore, the workpieces W may also slide relative to the conveying surface 10a for some reason. In the present embodiment, even if deviation of the workpieces W in the width direction, sliding relative to the conveying surface 10a, etc. occur, the favorable drawing quality of the plotter 2 can be maintained, as will be described later.

[0092] Although not particularly limited, examples of the workpiece W may include packaging materials for packaging various products. As typical examples of packaging materials, for example, corrugated cardboard and the like can be mentioned. The inkjet printer 1 draws information, such as characters including numbers, symbols, bar codes, two-dimensional codes, images, marks, diagrams, and combinations thereof, on the workpiece W conveyed by the conveyor 10. In the case of drawing only characters, the inkjet printer 1 may also be referred to as a typing device, etc., and the drawing machine 2 may also be referred to as a typewriter. In addition, the information drawing of the inkjet printer 1 also includes the case of printing images, etc. In this case, the inkjet printer 1 may be referred to as a printing device. In the following description, typing and printing are simply referred to as drawing.

[0093] (Structure of Drawing Machine 2)

[0094] The plotter 2 is a plotter of a drop-on-demand (DOD) system that ejects ink only when a drawing operation is required, but may be a plotter of a continuous inkjet (CIJ) system that ejects ink even when a drawing operation is not performed other than the DOD system. Hereinafter, a case where a plotter of the DOD system is used as the plotter 2 of the present embodiment will be described.

[0095] like Figure 2 As shown in FIG. 1 , the plotter 2 includes an ink supply unit 20, an ink channel unit 21, an ink discharge unit 22, a print head driving unit 23, and a DOD print head (hereinafter referred to as a print head) 24. The plotter 2 also includes a main housing 25, and the print head 24 is disposed in the main housing 25. A member 25A (in FIG. 2A ) constituting the main housing 25 Figure 1 and Figure 3 ) is an attachment portion configured to fix the inkjet printer 1 at the attachment position. Figure 3 As shown, the inkjet printer 1 can be fixed so as not to move from a predetermined attachment position by attaching a member 25A constituting the main housing 25 to the fixing member 11. The attachment portion may be, for example, a bracket, a fastening member such as a bolt or a screw, or the like.

[0096] The print head 24 is fixed in a state of being accommodated in the main housing 25, and the positional relationship between the main housing 25 and the print head 24 is fixed. In addition, the ink supply unit 20, the ink channel unit 21, the ink discharge unit 22 and the print head driving section 23 are also accommodated in the main housing 25.

[0097] The print head 24 of the plotter 2 of the DOD system is a member corresponding to the nozzle of the present invention, and ejects ink to draw information on the workpiece W. The print head 24 has various types of structures, for example, any of a thermal inkjet type, a valve ejection type, and a piezoelectric type can be used. In the present embodiment, a piezoelectric type print head capable of performing drawing at low resolution to high resolution, having a wide drawing width, and having high durability is used as the print head 24.

[0098] like Figure 4 As shown in FIG. 2 , the print head 24 includes a plurality of ejection ports 24a formed in the up-down direction (first direction). Figure 3 As shown, an opening 25a that is long in the up-down direction is formed on the surface of the main housing 25 that is opposite to the workpiece W. The surface of the print head 24 on which the ejection port 24a is formed is arranged to face the outside through the opening 25a of the main housing 25. Therefore, the ink ejected from the ejection port 24a of the print head 24 flies out of the main housing 25 from the opening 25a of the main housing 25 and adheres to the workpiece W.

[0099] Figure 4 The ink channel of the plotter 2 is shown. The ink supply unit 20 is a portion that supplies ink to the ink channel unit 21, and includes an ink cartridge 20a. The ink cartridge 20a is detachably attached to the main body portion of the ink supply unit 20, that is, the main housing 25. When the ink in the ink cartridge 20a is exhausted, the ink cartridge 20a can be replaced. Instead of the ink cartridge 20a, an ink reservoir that can be refilled with ink may be provided.

[0100] The ink channel unit 21 includes a sub-tank 21a storing ink supplied from the ink cartridge 20a, an upstream channel 21b, and a downstream channel 21c. The ink cartridge 20a and the sub-tank 21a are ink tanks storing ink. In this embodiment, the hydraulic head pressure of the ink level in the sub-tank 21a is applied to the print head 24 as a negative pressure. Therefore, the ink ejected from the print head 24 is sucked from the sub-tank 21a by the capillary action of the nozzle orifice (not shown) formed in the print head 24 and replenished. In addition, the meniscus of the ink replenished to the print head 24 is in a position corresponding to the balance between the capillary action of the nozzle orifice and the hydraulic head pressure of the ink level in the sub-tank 21a. The ink is supplied from the ink cartridge 20a to the sub-tank 21a so that the hydraulic head pressure of the ink level in the sub-tank 21a is within a range that does not destroy the meniscus.

[0101] Since the structure of supplying the ink in the sub-tank 21a to the print head 24 using the hydraulic head pressure of the ink level in the sub-tank 21a is adopted in the present embodiment, the plotter 2 is installed so that the ink level in the sub-tank 21a is within a predetermined tilt range relative to the horizontal plane. That is, as long as the ink can be supplied to the print head 24 using the hydraulic head pressure of the ink level in the sub-tank 21a during operation, the ink level in the sub-tank 21a is allowed to be tilted relative to the horizontal plane, and the plotter 2 is installed in such an installation posture. Note that in the present embodiment, the posture at the time of installation is adjusted so that the ink level in the sub-tank 21a is substantially horizontal.

[0102] The upstream channel 21b extends from the ink supply unit 20 to the sub-tank 21a, and is a channel for supplying ink in the ink cartridge 20a to the sub-tank 21a. The upstream channel 21b is provided with an upstream filter 21d for filtering ink, an ink pump 21e for supplying ink, and an upstream valve 21f for opening and closing the upstream channel 21b in sequence from the upstream side. The sub-tank 21a is provided with a level meter 21g for measuring the liquid level height of the ink in the sub-tank 21a. The level meter 21g can be configured using, for example, a float sensor, a capacitance sensor, an ultrasonic level sensor, etc. The ink pump 21e and the upstream valve 21f are controlled by an ink channel control unit 40a ( Figure 2 ) is controlled and the liquid level height is adjusted so that the liquid level height measured by the level meter 21g is within a predetermined range.

[0103] The downstream channel 21c extends from the sub-tank 21a to the print head 24, and is a channel for supplying the ink in the sub-tank 21a to the print head 24. The downstream channel 21c is provided with a downstream valve 21h that opens and closes the downstream channel 21c and a downstream filter 21i that filters the ink in sequence from the upstream side. The downstream valve 21h is controlled by an ink channel control unit 40a described later, and is opened when drawing is performed. Since such an ink channel unit 21 is provided, the ink that has been supplied from the ink cartridge 20a to the sub-tank 21a can be supplied from the sub-tank 21a to the print head 24, and the ink that has been supplied to the print head 24 can be ejected from the ejection port 24a toward the workpiece W.

[0104] The ink channel unit 21 further includes a pressure regulating channel 26. One end of the pressure regulating channel 26 is communicated with the upper part (the part where air accumulates) of the sub-tank 21a, and the other end of the pressure regulating channel 26 is open to the atmosphere. The pressure regulating channel 26 is provided with a first valve 26a, a second valve 26b, a pressure sensor 26c, an air pump 26d, and an air filter 26e. The pressure sensor 26c is configured to detect the pressure in the part between the first valve 26a and the second valve 26b in the pressure regulating channel 26. In addition, the second valve 26b may be always open except during the transportation of the plotter 2. In this case, what is measured by the pressure sensor 26c is the pressure in the sub-tank 21a, and the inkjet pressure and amount in the cleaning operation can be controlled by controlling the pressure in the sub-tank 21a.

[0105] The air pump 26d is configured to supply air to a portion between the first valve 26a and the second valve 26b in the pressure regulating passage 26. For example, by controlling the air pump 26d, the first valve 26a and the second valve 26b at the time of maintenance of the plotter 2 or the like, the interior of the sub-tank 21a can be pressurized to a desired pressure with air. Before being sucked into the air pump 26d, the air is filtered by the air filter 26e.

[0106] The ink discharge unit 22 includes a discharge channel 22a for discharging ink in the print head 24, a discharge tank 22b, and a discharge valve 22c. The upstream end of the discharge channel 22a is connected to the print head 24, and the downstream end of the discharge channel 22a is connected to the discharge tank 22b. The discharge valve 22c is provided in the middle portion of the discharge channel 22a, and is configured to open and close the discharge channel 22a. For example, during maintenance of the plotter 2 or before transportation of the plotter 2, the ink in the downstream channel 21c and the print head 24 can be discharged to the discharge tank 22b by pressurizing the inside of the sub-tank 21a by the air pump 26d of the pressure regulating channel 26.

[0107] Figure 2 The print head driving section 23 shown in FIG. 1 is controlled by a drawing control unit 40 c described later when a drawing operation is performed. The print head driving section 23 generates a driving electrical waveform for driving the print head 24, and outputs the driving electrical waveform to the print head 24. The driving electrical waveform is a waveform for individually driving driving elements (piezoelectric vibrators) respectively provided for a plurality of ejection ports 24 a of the print head 24 at a timing based on a drawing command output from the drawing control unit 40 c.

[0108] (Detailed description of channel control)

[0109] 1. Initial filling control

[0110] The initial filling control is a control for replacing the air in the print head 24 with ink and filling the print head 24 with ink before starting the operation of the inkjet printer 1. First, the sub-tank 21a is filled with ink. Figure 2 The ink channel control unit 40a is shown open. Figure 4 The downstream valve 21h, the second valve 26b and the discharge valve 22c shown are closed, and the first valve 26a and the upstream valve 21f are closed. In addition, the ink pump 21e is closed and the air pump 26d is opened. Therefore, the downstream channel 21c, the interior of the print head 24, and the portion between the print head 24 and the discharge valve 22c are filled with ink in the sub-tank 21a to replace the air.

[0111] 2. Control of ink supply to the sub-tank 21a

[0112] The ink supply control to the sub-tank 21a is a control to keep the liquid level height of the ink in the sub-tank 21a within a certain range. The ink channel control unit 40a opens the first valve 26a, the second valve 26b and the upstream valve 21f, and also opens the downstream valve 21h. In addition, the ink pump 21e is turned on and the air pump 26d is turned off. Therefore, the ink can be supplied from the ink cartridge 20a to the sub-tank 21a so that the liquid level height measured by the level meter 21g is always constant. For example, the amount of ink delivered from the sub-tank 21a to the print head 24 side can be roughly estimated by software so that the ink supply operation is not performed until the level meter 21g detects the opening (ON) when the liquid level height measured by the level meter 21g is reduced to a specific liquid level.

[0113] 3. Control of ink supply to print head 24

[0114] In this control, the ink channel control unit 40a opens the downstream valve 21h, the first valve 26a and the second valve 26b, and closes the upstream valve 21f and the discharge valve 22c. In addition, the ink pump 21e and the air pump 26d are turned off. Therefore, when the ink is ejected from the print head 24, the ink is sucked from the sub-tank 21a to the nozzle orifice in the print head 24 due to the capillary action. At this time, the ink level in the sub-tank 21a is set to be lower than the ejection port 24a at the lowermost end of the print head 24 in the gravity direction, so that the ink in the print head 24 always has a negative pressure, the negative pressure of the nozzle orifice and the capillary action are balanced, and the ink meniscus is formed at the specified position of the nozzle orifice. That is, the positional relationship in the height direction between the print head 24 and the ink level in the sub-tank 21a is set so as to obtain a negative pressure that forms an ink meniscus at a specified position.

[0115] 4. Print head cleaning control

[0116] The print head cleaning control is a control to remove the air or foreign matter (such as paper dust adhering to the surface of the nozzle orifice or the inside of the nozzle orifice) mixed in the print head 24 due to the rupture of the curved surface of the nozzle orifice to the outside of the print head 24. The ink channel control unit 40a opens the second valve 26b and closes the first valve 26a, the downstream valve 21h, the upstream valve 21f and the discharge valve 22c. In addition, the ink pump 21e is turned off and the air pump 26d is turned on. This control is performed, the air pressure in the sub-tank 21a is measured by a pressure gauge, and pressurization is performed by the air pump 26d until a certain pressure is obtained.

[0117] Thereafter, the ink passage control unit 40a opens the downstream valve 21h and closes the upstream valve 21f, the first valve 26a, the second valve 26b, and the discharge valve 22c. In addition, the ink pump 21e and the air pump 26d are turned off. Therefore, by pressurizing with the air pressure in the sub-tank 21a, the ink in the sub-tank 21a is supplied to the print head 24, so that the air and foreign matter (such as paper dust adhering to the surface of the nozzle orifice and the inside of the nozzle orifice) mixed in the print head 24 are removed to the outside of the print head 24.

[0118] 5. Discharge control

[0119] The discharge control is a control for emptying all the ink in the ink channel. Before executing this control, the ink cartridge 20a is disassembled. Thereafter, the ink channel control unit 40a opens the first valve 26a, the second valve 26b and the upstream valve 21f, and also opens the downstream valve 21h. In addition, the ink pump 21e is turned on, and the air pump 26d is turned off. Therefore, all the ink in the upstream channel 21b is transferred to the sub-tank 21a.

[0120] Thereafter, the downstream valve 21h, the second valve 26b and the discharge valve 22c are opened, and the first valve 26a and the upstream valve 21f are closed. In addition, the ink pump 21e is closed, and the air pump 26d is opened. Therefore, the ink in the sub-tank 21a is pressurized by the air pump 26d to discharge the ink to the discharge tank 22b via the interior of the downstream passage 21c, the interior of the print head 24, and the portion between the print head 24 and the discharge valve 22c, so that the ink in these portions is replaced by air. At this time, some ink is also discharged from the print head 24.

[0121] (Structure of controller 4)

[0122] like Figure 2As shown, the controller 4 includes a control section 40, a power supply unit 41, a storage unit 42, and an operation display unit 43. The control section 40 includes, for example, a microcomputer including a central processing unit, various memories, etc., and can execute pre-stored software. The control section 40 includes an ink channel control unit 40a, a drawing data generation unit 40b, a drawing control unit 40c, a workpiece movement amount acquisition unit 40d, a workpiece distance acquisition unit 40e, a drawing start timing acquisition unit 40f, a conveying direction recognition unit 40g, an evaluation unit 40h, and an abnormality processing unit 40i. The respective units 40a-40i of the control section 40 are parts composed of hardware and software, and for convenience, are described as each of the units 40a-40i, but can also be integrated according to hardware.

[0123] The power supply unit 41 is a part that converts AC power from the commercial power supply 100 into DC power and supplies the DC power to, for example, the control section 40, the storage unit 42, the operation display unit 43, the plotter 2, etc., and includes, for example, a switching power supply.

[0124] The storage unit 42 is a portion that stores drawing data specifying the discharge timing of the ejection ports 24a of the print head 24, the drawing data corresponding to drawing information at each of a plurality of offset positions in the conveying direction. The storage unit 42 may include, for example, a work memory or the like. Figure 5 An example of plotting data is shown. Figure 5 The longitudinal direction in FIG. 1 is the array direction of the ejection ports 24 a of the print head 24 , and in the present embodiment, is the up-and-down direction during drawing. Figure 5 The horizontal direction in the figure is the conveying direction of the workpiece W, that is, the time axis direction, and the reference numerals L1, L2, L3, L4, L5, L6 and L7 respectively represent the ejection timings. The timings indicated by the reference numerals L1 to L7 are respectively referred to as the first to seventh ejection timings. The first ejection timing L1 is the drawing start timing, and the seventh ejection timing L7 is the drawing end timing. When based on Figure 5 When the drawing data shown executes the drawing process, the first ejection timing L1 to the seventh ejection timing L7 occur sequentially, and the print head 24 is controlled so that ink is ejected only from the ejection ports 24a corresponding to the cells shown in black in the figure.

[0125] like Figure 2As shown, the operation display unit 43 includes a plotter-side display unit 43a such as a liquid crystal display and a plotter-side operation unit 43b including operation keys and the like. The plotter-side operation unit 43b is a portion that receives various operations such as plotting settings regarding the workpiece W, installation settings of the plotter 2, and maintenance execution instructions performed by the user. A plotting setting screen, an installation screen, a maintenance execution instruction screen, and the like are displayed on the plotter-side display unit 43a, and the user can operate the plotter-side operation unit 43b while observing the plotter-side display unit 43a.

[0126] The ink channel control unit 40a of the control section 40 is a part that outputs execution commands of the above-mentioned channel controls 1 to 4 to the plotter 2 in response to instructions from the user using the plotter-side operation unit 43b, inputs from various sensors, etc. Each control after the ink channel control unit 40a outputs the execution command to the plotter 2 is as described above.

[0127] The drawing data generating unit 40b generates the drawing data based on the input contents, setting contents, etc. input from the terminal side display unit 5a and the drawing machine side operation unit 43b. Figure 5 The drawing data generated by the drawing data generating unit 40b is stored in the storage unit 42, for example.

[0128] The drawing control unit 40c reads the drawing data stored in the storage unit 42, and receives information on the position and distance and a signal (timing signal) indicating that the workpiece W has reached a predetermined position input from the sensor unit 3, the encoder 7, the timing sensor 8, etc. Then, the drawing control unit 40c outputs a control signal to the print head driving section 23 based on the information on the position and distance, the timing signal, and the drawing data generated by the drawing data generating unit 40b, and controls the ejection of ink from the ejection port 24a of the print head 24. The details of the drawing control unit 40c will be described later.

[0129] The workpiece movement amount acquisition unit 40d is a part that acquires the movement amount of the workpiece W relative to the plotter 2 based on the signals input from the sensor unit 3 and the encoder 7. When the workpiece movement amount acquisition unit 40d detects the movement amount of the workpiece W, the position of the workpiece W relative to the plotter 2 can be acquired. The movement amount and position of the workpiece W acquired by the workpiece movement amount acquisition unit 40d are input to the plotting control unit 40c.

[0130] The workpiece distance acquisition unit 40e is a part that acquires the timing (drawing start timing) at which the drawing machine 2 starts drawing based on the signals input from the sensor unit 3 and the timing sensor 8. The drawing start timing acquired by the workpiece distance acquisition unit 40e is input to the drawing control unit 40c.

[0131] The drawing start timing acquisition unit 40f is a part that acquires the timing of the workpiece W crossing the predetermined drawing start position based on the signal input from the sensor unit 3 and the timing sensor 8. The signal acquired by the drawing start timing acquisition unit 40f is input to the drawing control unit 40c. The signal input from the sensor unit 3 and the timing sensor 8 is used as a trigger for starting drawing (drawing start trigger).

[0132] The conveying direction recognition unit 40g is a portion that recognizes the conveying direction of the workpiece W based on the output from the sensor unit 3. In the case where the workpiece W is conveyed in the horizontal direction, the conveying direction recognition unit 40g recognizes that the workpiece W is conveyed in the horizontal direction, and outputs the recognized result to the drawing control unit 40c. In addition, in the case where the workpiece W is conveyed in an inclined direction, the conveying direction recognition unit 40g recognizes that the workpiece W is conveyed in the inclined direction, recognizes the inclination angle of the inclined direction, and outputs the recognized result to the drawing control unit 40c. As will be described later, the drawing control unit 40c controls the ejection of ink from the ejection port 24a of the print head 24 based on the conveying direction of the workpiece W recognized by the conveying direction recognition unit 40g.

[0133] Figure 6 This is a perspective view of the plotter 2 to which the sensor unit 3 is fixed, viewed from the inkjet side. The main housing 25 has a protrusion 25b formed so that the middle portion of the surface facing the workpiece W in the conveying direction protrudes toward the inkjet side. The opening 25a is formed at the front end surface of the protrusion 25b in the protruding direction.

[0134] The sensor unit 3 is fixed to the main housing 25 on the upstream side of the protrusion 25b on the surface opposite to the workpiece W in the conveying direction. On the other hand, an absorbing member 27 capable of absorbing ink is attached to the downstream side of the protrusion 25b on the surface opposite to the workpiece W in the conveying direction.

[0135] like Figure 7 As shown, the sensor unit 3 may be fixed to the downstream side of the protrusion 25b of the main housing 25 of the plotter 2 in the conveying direction. In addition, the sensor unit 3 may be fixed above the protrusion 25b of the main housing 25 of the plotter 2. Figure 7 As shown, three sensor units 3 can be fixed to one plotter 2, or Figure 7 Any two of the three sensor units 3 shown may be fixed. That is, the inkjet printer 1 including a plurality of sensor units 3 may also be configured.

[0136] (Structure of sensor unit 3)

[0137] like Figure 2As shown, the sensor unit 3 includes: an optical movement measuring sensor 30 that generates a measurement value related to the movement of the workpiece W relative to the print head 24; a distance sensor 31 that measures the distance to the workpiece W in the ejection direction of the print head 24; and a sensor housing 32 in which the optical movement measuring sensor 30 and the distance sensor 31 are accommodated. Both the optical movement measuring sensor 30 and the distance sensor 31 are sensors that perform measurement using measurement light, and thus correspond to optical measurement sensors. In other words, the sensor unit 3 constituting the optical measurement sensor of the present embodiment includes the optical movement measuring sensor 30 and the distance sensor 31.

[0138] The optical movement measurement sensor 30 and the distance sensor 31 are housed in a common sensor housing 32, thereby being integrated into a sensor module. With the sensor unit 3, it is possible to detect the drawing start timing, detect the conveying speed (moving distance) of the workpiece W, detect the distance of the workpiece W, and the like. Note that the distance to the workpiece W in the ejection direction of the print head 24 is also referred to as the distance to the workpiece W. In addition, although the expression of the distance to the workpiece W in the ejection direction of the print head 24 is used in the present embodiment, for convenience, this is defined only as the distance between the designated workpiece W and the plotter 2, and, for example, a definition as the distance between the ejection port 24a of the print head 24 and the drawing surface of the workpiece W or a definition as the distance between any part of the print head 24 and any part of the workpiece W may be used.

[0139] The optical movement measuring sensor 30 emits light in the ejection direction of the print head 24, receives light reflected from the workpiece W, and generates a measurement value related to the movement of the workpiece W in the conveying direction based on the received light. In the present embodiment, an optical tracking sensor (OTS) capable of obtaining the movement amount of the workpiece W by continuously photographing images of the workpiece W at high speed and performing image processing on the obtained images is used as such an optical movement measuring sensor 30. The OTS that can be used as the optical movement measuring sensor 30 may be a system that uses a light emitting diode as a light source to measure the movement amount of the photographed image, or a system that uses a laser as a light source to measure the movement amount of a speckle pattern. In the present embodiment, a system that uses a laser as a light source is adopted, which has a higher depth than a system that uses a light emitting diode as a light source. This is because the distance between the print head 24 and the workpiece W can vary, for example, by about 10 mm. Note that in addition to the OTS, a laser Doppler velocimeter or the like can also be used as the optical movement measuring sensor 30.

[0140] The OTS using a laser as a light source includes: a light projecting unit 30a that projects light (laser) onto the workpiece W; and a light receiving unit 30b that receives a speckle pattern generated by the light projected from the light projecting unit 30a according to the characteristics of the surface shape of the workpiece W, and generates light reception data including the speckle pattern. The light receiving unit 30b includes, for example, an imaging device having an image sensor such as a complementary MOS (CMOS). The field of view of the imaging device may overlap with the diameter of the spot light projected from the distance sensor 31 including a laser distance sensor described later.

[0141] The OTS generates a measurement value related to the movement of the workpiece W in the conveying direction based on the movement amount of the speckle pattern included in the light reception data generated by the light receiving unit 30 b. That is, the optical movement measurement sensor 30 can generate a measurement value related to the movement of the workpiece W based on a measurement image generated by photographing the workpiece W by an imaging device.

[0142] The optical movement measuring sensor 30 measures not only the amount of movement of the workpiece W in the conveying direction, but also the amount of movement in the direction perpendicular to the conveying direction. When measuring the amount of movement in the direction perpendicular to the conveying direction, the optical movement measuring sensor 30 also generates a measurement value related to the movement in the direction perpendicular to the conveying direction. Since the conveying direction of the workpiece W and the direction perpendicular to the conveying direction are orthogonal to each other, the optical movement measuring sensor 30 can generate measurement values ​​of two axes orthogonal to each other. In this case, the optical movement measuring sensor 30 determines the measurement value related to the movement of the workpiece W in the conveying direction based on the generated measurement values ​​of the two axes.

[0143] The optical system of the light receiving unit 30b does not include a lens. In this way, the optical system without a lens makes it possible to ensure that the depth of field of the light receiving unit 30b is greater than that of the optical system with a lens. Since the depth of field of the light receiving unit 30b is ensured to be large, the measurable range of the optical movement measurement sensor 30 can be widened. This makes it possible to measure the workpiece W passing through a position far away from the print head 24, so that the degree of freedom of the conveying position of the workpiece W is increased, the cost of the manufacturing production line can be reduced, and the necessity of confirming the conveying position of the workpiece W can be reduced. In addition, the range of distances that can be used is widened, thereby increasing the degree of freedom of the installation method of the plotter 2. Note that the optical system of the light receiving unit 30b may include a lens.

[0144] As the distance sensor 31, for example, a conventionally known device such as a triangulation distance sensor, a time offlight (TOF) distance sensor, or an ultrasonic sensor can be used. The distance sensor 31 of the present embodiment is a laser distance sensor capable of projecting spot light generated by laser to a measured object.

[0145] The distance sensor 31 and the optical movement measuring sensor 30 are arranged at substantially the same height. Specifically, in a state where the distance sensor 31 and the optical movement measuring sensor 30 are fixed to the sensor housing 32, the height of the measurement light projected from the distance sensor 31 and the height of the measurement light projected from the optical movement measuring sensor 30 coincide with each other. Therefore, the same height portion of the workpiece W can be measured by the distance sensor 31 and the optical movement measuring sensor 30.

[0146] The attachment positions of the distance sensor 31 and the optical movement measuring sensor 30 in the height direction can be adjusted. For example, in order to adjust the positions of the distance sensor 31 and the optical movement measuring sensor 30 in the height direction, the adjustment can be performed by moving the housing 32 itself up and down relative to the main housing 25. In addition, for example, the sensor housing 32 is provided with an attachment mechanism configured to attach the distance sensor 31 to the sensor housing 32 and an attachment mechanism for attaching the optical movement measuring sensor 30 to the sensor housing 32. The attachment mechanism of the distance sensor 31 is configured to be able to change the height of the distance sensor 31 within a predetermined range. In addition, the attachment mechanism of the optical movement measuring sensor 30 is configured to be able to change the height of the optical movement measuring sensor 30 within a predetermined range. Therefore, the distance sensor 31 and the optical movement measuring sensor 30 can be arranged at the same height. Note that the distance sensor 31 and the optical movement measuring sensor 30 can be arranged at different heights. The distance sensor 31 and the optical movement measuring sensor 30 can be directly attached to the plotter 2, or can be indirectly attached to the plotter 2 while maintaining a specific relationship with the plotter 2, and all these attachment forms are included in the form of being attached to correspond to the plotter 2.

[0147] Since a timing signal can be generated based on the distance data measured by the distance sensor 31, the distance sensor 31 can also be called an optical timing sensor. Specifically, a timing signal indicating that the reference position of the workpiece W is at a predetermined position can be generated based on a change in the distance to the workpiece W in the ejection direction of the print head 24 measured by the distance sensor 31. The distance sensor 31 is arranged on the downstream side of the optical movement measuring sensor 30 in the conveying direction of the workpiece W, and can identify the drawing start timing at this position. Since the distance sensor 31 is arranged on the downstream side of the optical movement measuring sensor 30 in the conveying direction of the workpiece W, the optical movement measuring sensor 30 can generate a measurement value related to the movement of the workpiece W before the distance sensor 31 generates a timing signal. Note that the generation of the timing signal by the distance sensor 31 and the generation of the measurement value by the optical movement measuring sensor 30 can be performed at the same timing.

[0148] The sensor housing 32 accommodating the optical movement measuring sensor 30 and the distance sensor 31 is detachably fixed to the main housing 25. Figure 6As shown, the front surface 32a of the sensor housing 32 has a window 32b formed by a light-transmitting cover for transmitting light. The light receiving unit 30b (eg, Figure 2 The optical movement measuring sensor 30 and the distance sensor 31 are configured to capture an image of the workpiece W through the window 32 b. In addition, the distance sensor 31 irradiates the measuring light to the workpiece W through the window 32 b, and receives the measuring light reflected by the workpiece W through the window 32 b. That is, the optical movement measuring sensor 30 and the distance sensor 31 are configured to be able to measure the workpiece W through the window 32 b.

[0149] Since the main housing 25 is provided with the print head 24, the optical movement measuring sensor 30 and the distance sensor 31 are fixed to the main housing 25 so that the relative positional relationship with the print head 24 is a predetermined positional relationship. Examples of the fixing structure that can be detached may include, but are not limited to, a fastening structure using screws or bolts, and a structure in which a first engaging portion provided in the sensor housing 32 is engaged with a second engaging portion provided in the main housing 25.

[0150] The optical movement measuring sensor 30 and the distance sensor 31 are attached at fixed positions relative to the print head 24 so that the positional relationship among the optical movement measuring sensor 30, the distance sensor 31, and the print head 24 becomes a known value in the conveying direction of the workpiece W. Since the optical movement measuring sensor 30 and the distance sensor 31 are accommodated in a common sensor housing 32, the distance sensor 31 is arranged at a position offset in the same direction as the optical movement measuring sensor 30 relative to the print head 24 along the conveying direction.

[0151] Note that the user may be allowed to input the positions to which the optical movement measuring sensor 30 and the distance sensor 31 are attached as setting values ​​to the control section 40. This makes it possible to improve drawing accuracy while increasing the degree of freedom of installation of the optical movement measuring sensor 30 and the distance sensor 31.

[0152] like Figure 3 As shown, the optical movement measuring sensor 30 of the sensor unit 3 is arranged at a position offset in the conveying direction relative to the print head 24, specifically, at a position offset relative to the upstream side in the conveying direction. The plotter 2 is installed so that the position in the up-down direction (first direction) of the drawing target area to which the ejection outlet 24a of the print head 24 points and the position in the up-down direction of the area where the current offset position is measured by the optical movement measuring sensor 30 at least partially overlap each other. This makes it possible to accurately obtain a measurement value related to the movement of the drawing target area.

[0153] The optical movement measuring sensor 30, the distance sensor (also used as a timing sensor) 31 and the print head 24 are arranged in order from the upstream side in the conveying direction of the workpiece W. With this array, the movement amount of the workpiece W can be measured starting with the optical movement measuring sensor 30 outputting a valid measurement value.

[0154] In addition, the optical movement measuring sensor 30 and the distance sensor 31 are arranged at a position offset upstream of the print head 24 along the conveying direction for the following reason. That is, due to the wind flow generated by conveying the workpiece W to the print head 24, the ink mist (called splash) generated during the ink ejection from the print head 24 and not falling on the workpiece W and the ink droplets splashed from the workpiece W flow in the downstream direction of the print head 24. For this reason, if the optical movement measuring sensor 30 and the distance sensor 31 are installed downstream of the print head 24, the window 32b serving as the detection surface of the optical movement measuring sensor 30 and the distance sensor 31 is likely to be contaminated by ink to cause a detection failure. However, in this case, in principle, a dead zone that the optical movement measuring sensor 30 cannot measure is generated at the most terminal (downstream end) of the workpiece W in the conveying direction. In the case where drawing is to be performed on the dead zone, it is sufficient to perform complementary processing such as constant speed control using the final measurement value of the optical movement measuring sensor 30 or acceleration control using the final acceleration measured by the optical movement measuring sensor 30.

[0155] When the workpiece W is conveyed to a predetermined position relative to the print head 24, the print head 24 is guided to the drawing target area in the workpiece W. In addition, the distance sensor 31 can measure the current offset position by irradiating the workpiece W with the measurement light, and the area of ​​the workpiece W irradiated with the measurement light by the distance sensor 31 is the measurement area of ​​the distance sensor 31 for the workpiece W. In the present embodiment, the distance sensor 31 is installed so that the position in the up-down direction of the drawing target area pointed by the print head 24 and the position in the up-down direction of the area where the current offset position is measured by the distance sensor 13 at least partially overlap with each other. That is, the area where drawing is performed and the area measured by the distance sensor 31 at least partially overlap with each other, so that the distance of the area where drawing is performed from the print head 24 can be accurately measured.

[0156] (Drawing Settings)

[0157] Will refer to Fig. 8A The flowchart shown describes the drawing setting performed before the operation of the inkjet printer 1. To perform the drawing setting, the user uses, for example, the terminal side display unit 5a and the terminal side operation unit 5b of the operation terminal 5 or the operation display unit 43 of the controller 4. A setting screen (GUI) is displayed on the terminal side display unit 5a or the plotter side display unit 43a. The terminal side operation unit 5b or the plotter side operation unit 43b receives the user's setting operation.

[0158] exist Fig. 8A In step SA1, the user performs initial settings. In the initial settings, the user selects a GUI language, inputs device configuration such as the number of plotters 2, and inputs device installation information. The device installation information includes layout information of the plotters 2 (tilt of the plotters 2, etc.), line flow direction information on the plotters 2, transmission speed information, etc. The control section 40 acquires the contents of the selection operation and input operation of the user.

[0159] In step SA2, the user performs drawing general setting. In drawing general setting, the user performs manufacturing serial number counter setting and replacement setting (such as obfuscation setting of manufacturing date or lot number).

[0160] In step SA3, it is waited for the user to start drawing setting. Specifically, it is determined whether the user has started drawing setting. When drawing setting is started, the process proceeds to step SA4. In step SA4, it is determined whether to draw a logo (image). When an image is to be drawn, the process proceeds to step SA5, and the image data is converted into a resolution and size that can be drawn by the plotter 2 using a dedicated terminal such as a personal computer to obtain a dedicated logo file, and the logo file is stored in the storage unit 42 of the plotter 2.

[0161] When it is determined as "No" in step SA4 and the image is not drawn, the process proceeds to step SA6. In step SA6, the user performs drawing content setting. Specifically, the user selects a job number to be set as a drawing content, or selects a drawing content to be edited by a job number. A job represents a drawing data set to be drawn on a workpiece W, and the job includes such as Figure 5 Plot data shown.

[0162] In step SA7, the user sets a delay from receiving a drawing start trigger commonly used in the job selected in step SA6 to the start of drawing. The delay from receiving a drawing start trigger to the start of drawing can be set by setting, for example, time or position (mm).

[0163] In step SA8, a drawing element (block) is added to the job. Thereafter, the process proceeds to step SA9, and in step SA9, a drawing element such as a character string, a barcode, a two-dimensional code, or a logo is set in the added drawing element. At this time, the user sets the thickness of the characters to be drawn, the character size, the barcode size, the two-dimensional code size, the logo size, its position information, etc. The drawing data also includes the print pitch, etc.

[0164] In step SA10, it is determined whether the addition of drawing elements has been completed. Steps SA8, SA9, and SA10 are repeated until the addition of all drawing elements is completed, and when the addition of all drawing elements is completed, the process proceeds to step SA11. In step SA11, the job is stored in the storage unit 42 of the plotter 2.

[0165] (Installation Assisted Mode)

[0166] Since the ink supply to the print head 24 is performed using the hydraulic head pressure of the ink level in the sub-tank 21a in the inkjet printer 1 of the present embodiment, it is necessary to install the plotter 2 so as to fall within a predetermined tilt range when installing the plotter 2. As a measure for such adjustment, for example, it is possible to design so as to adjust the posture of the plotter 2 by the horizontal height. However, in the case of posture adjustment by the horizontal height, there is a problem that it is difficult for the user to notice the change over time after the plotter 2 is installed. In addition, secondly, the conveying speed of the workpiece W is acquired from the setting of the conveyor 10, or a speed measuring device such as the encoder 7 is required. In addition, it is necessary to temporarily stop the workpiece W and measure the distance between the workpiece W and the print head 24 in order to confirm that the plotter 2 has been installed within the specifications of the plotter 2, although this depends on the relative position of the plotter 2 relative to the workpiece W. In addition, unless drawing is actually performed on the workpiece W, the tilt of drawing and the drawing quality are unknown, and it is necessary to repeat drawing, install the plotter 2, and correct various settings.

[0167] On the other hand, in the inkjet printer 1 of the present embodiment, an installation assistance mode can be executed for assisting the user in the installation work of the plotter 2 and reducing the load of the installation work performed by the user. Figure 8B The flowchart shown describes the installation assistance mode in detail.

[0168] For example, in Fig. 8A After the drawing settings shown, the inkjet printer 1 responds to an instruction from the user or automatically proceeds to Figure 8B In step SA100, the control section 40 performs processing for switching to the mounting assist mode. In step SA101, monitoring by the optical movement measuring sensor 30 and the distance sensor 31 is started. In step SA102, when the workpiece W is conveyed, the optical movement measuring sensor 30 and the distance sensor 31 measure the workpiece W. In this step SA102, the drawing processing is not performed.

[0169] In step SA103, the measurement results of the optical movement measuring sensor 30 and the distance sensor 31 are displayed. Figure 2As shown, the controller 4 includes an output unit 44, and the output unit 44 is a part that outputs information about the installation state based on the measurement values ​​generated by the optical movement measuring sensor 30 and the distance sensor 31. For example, the output unit 44 generates Figure 8C The measurement result display screen 50 shown is displayed on the plotter-side display unit 43a or the terminal-side operation unit 5b. At least one of the plotter-side display unit 43a and the terminal-side operation unit 5b is a display unit that displays information on the installation status output from the output unit 44. The output of the output unit 44 includes external output and internal output.

[0170] The measurement result display screen 50 includes: a workpiece size display area 51, in which the workpiece size of the workpiece W in the conveying direction is displayed; a workpiece conveying speed display area 52, in which the average conveying speed of the workpiece W is displayed; a distance display area 53, in which the maximum distance between the print head 24 and the workpiece W is displayed; a longitudinal movement amount display area 54, in which the movement amount of the workpiece W in the direction perpendicular to the conveying direction is displayed; and a tilt display area 55, in which the tilt of the plotter 2 is displayed.

[0171] The workpiece size, the conveying speed of the workpiece W, the distance between the print head 24 and the workpiece W, the movement amount of the workpiece W in the direction perpendicular to the conveying direction, and the inclination of the plotter 2 are generated based on the measurement values ​​of the optical movement measuring sensor 30 and the distance sensor 31 included in the sensor unit 3, and are examples of information about the installation state. Information about the installation state other than these can be displayed on the measurement result display screen 50.

[0172] The output unit 44 may also output a graph (an example of information) showing the relationship between the distance measured by the distance sensor 31 (the distance between the print head 24 and the workpiece W) and the specified distance range (also referred to as the drawing distance range) specified by the specification of the plotter 2 as the information on the installation state. Figure 8C The distance measured by the distance sensor 31 is shown, and the output unit 44 generates and outputs a graph indicating whether the distance is within or outside a specified distance range, so that the user can confirm the installation status related to the distance on the measurement result display screen 50.

[0173] The output unit 44 can also output a graph showing the relationship between the conveying speed of the workpiece W measured by the optical movement measuring sensor 30 (which is the moving speed of the workpiece W) and the specified speed range specified in the specification as information on the installation state. Figure 8CAs shown, the conveying speed measured by the optical movement measuring sensor 30 is displayed, and the output unit 44 generates and outputs a graph indicating whether the speed is within or outside the specified speed range, so that the user can confirm the installation status related to the speed on the measurement result display screen 50.

[0174] The output unit 44 may also output a graph showing the inclination of the conveying direction determined from the measurement values ​​of the two axes measured by the optical movement measuring sensor 30 as information on the installation state. Figure 8C As shown, the inclination of the conveying direction can be indicated by schematically illustrating the plotter 2 and tilting the schematic diagram.

[0175] When the user operates Figure 8C When the detail button 56 is pressed on the measurement result display screen 50 shown in FIG. Fig.8D The detailed display screen 60 is shown in FIG. 4 and is displayed on the plotter-side display unit 43a or the terminal-side operation unit 5b. The detailed display screen 60 is provided with a graph display area 61 for displaying the time series change of the measurement data in a graph format. For example, it can be seen that by observing Fig.8D , the workpiece W moves in a direction (inclined direction) gradually separating from the plotter 2.

[0176] exist Figure 8B In step SA104, it is determined whether there is no problem in the installation state based on the measurement result displayed in step SA103. For example, it is determined whether the maximum value of the distance between the workpiece W and the print head 24 is within the specification of the plotter 2, and if the maximum value exceeds the specification, it is determined that there is a problem with the installation position of the plotter 2. The determination in step SA104 can be performed by the user or can be performed by the controller 4. Fig.8D In the example shown in the detailed display screen 60 of , it is necessary to adjust the relative positional relationship between the plotter 2 and the workpiece W so that the plotter 2 approaches the workpiece W.

[0177] When the distance between the workpiece W and the print head 24 is measured to be gradually changed, it is determined that there is a problem with the mounting state because the workpiece is moving obliquely. In this case, the angle needs to be adjusted.

[0178] When the distance between the workpiece W and the print head 24 varies greatly, it is determined that there is a problem with the mounting state because the plotter 2 has not been fixed or the guide of the workpiece W is unstable. In this case, it is necessary to fix the plotter 2 and adjust the guide.

[0179] The size of the workpiece W can be acquired based on the moving distance of the workpiece W in the conveying direction, and it can be known whether the relationship between the moving distance of the workpiece W in the conveying direction and the drawing size is satisfied. If the relationship between the moving distance of the workpiece W in the conveying direction and the drawing size is not satisfied, it is determined that there is a problem with the installation state.

[0180] In the case where there is a large variation in the conveying speed of the workpiece W in the constant speed drawing setting, printing based on the constant speed drawing setting cannot be performed, and therefore, it is determined that there is a problem with the mounting state.

[0181] The fact that the movement amount of the workpiece W in the direction perpendicular to the conveying direction monotonically increases or decreases indicates that the workpiece W moves obliquely relative to the plotter 2 , and thus it is determined that there is a problem in the mounting state.

[0182] The situation where the vibration in the direction perpendicular to the conveying direction of the workpiece W is large indicates that the workpiece W is bumping (to be described later) or the plotter 2 is not completely installed, so it is determined that there is a problem with the installation state. In this case, it is necessary to check the adjustment of the conveyor 10 or the installation of the plotter 2.

[0183] When it is determined that there is a problem with the installation position of the plotter 2, the process proceeds from step S104 to step SA101. When it is determined that there is no problem with the installation position of the plotter 2, the process proceeds from step S104 to step SA105, and the measurement result is reflected in the plotting setting.

[0184] There is a case where the workpiece W is conveyed at a certain angle relative to the horizontal direction. In this case, if the plotter 2 is also tilted in a manner matching the conveying direction of the workpiece W, there is no problem in drawing, but there is a case where the plotter 2 cannot be tilted in a manner matching the conveying direction of the workpiece W as described above. In this case, Fig. 8E As shown on the upper side of FIG. 1 , a process for tilting the image to be drawn at an angle α to match the conveying direction of the workpiece W is performed, and the drawing control unit 40 c controls inkjet based on the image that has been processed, so that the final drawing result can be as shown in FIG. Fig. 8E The specific process will be described later.

[0185] There are cases where the optical movement measuring sensor 30 that measures the amount of movement of the workpiece W needs to be calibrated according to the state of the workpiece W, etc. The installation assist mode has an advantage that installation adjustment can be performed without actually drawing on the workpiece W, but a correction image can be drawn to calibrate the optical movement measuring sensor 30 in the installation assist mode as needed. For example, the correction image assumes that a reference image including a plurality of print patterns having a predetermined interval from the print head 24 is drawn on the workpiece W. The correction image is drawn by the drawing control unit 40c.

[0186] Fig.8F An example of a first correction image is shown. After the first correction image is drawn, the dimensions are measured, and the deviation between the measured dimensions and the first correction image is used as a correction coefficient, whereby the optical movement measuring sensor 30 can be calibrated. Figure 8G A correction value input screen 70 is shown, which is provided with an input area 71 to which the measurement result of the first correction image after drawing is input. The correction coefficient can be calculated based on the value input to the input area 71 and the size of the first correction image with respect to the drawing data.

[0187] Figure 8H An example of a first correction image is shown. When such a grid-like pattern is at regular intervals, the optical movement measuring sensor 30 can be calibrated, and the movement amount in the direction perpendicular to the conveying direction and the movement amount in the tilt direction of the workpiece W can be visually recognized.

[0188] As described above, the drawing control unit 40 c draws the correction image assumed to be drawn on the workpiece W at a predetermined interval from the print head 24 on the workpiece, and receives an input of the drawing result of the correction image drawn on the workpiece W. Then, the drawing control unit 40 c performs calibration based on a comparison between the drawing result of the correction image and the predetermined interval.

[0189] (Control of the drawing control unit)

[0190] Figure 2 The drawing control unit 40c shown acquires reference position information indicating that the reference position of the workpiece W is at a predetermined position and a measurement value generated by the optical movement measuring sensor 30. After acquiring the reference position information and the measurement value output from the optical movement measuring sensor 30, the drawing control unit 40c controls the ejection of ink from the ejection port 24a of the print head 24 according to the current offset position relative to the reference position based on the reference position information and the measurement value output from the optical movement measuring sensor 30, and the drawing data.

[0191] The reference position information acquired by the drawing control unit 40c is a timing signal indicating that the workpiece W conveyed by the conveyor 10 has reached a predetermined position. Since the timing sensor 8 is a sensor that detects that the workpiece W conveyed by the conveyor 10 has reached a predetermined position, the drawing control unit 40c acquires a signal output from the timing sensor 8 as a timing signal. In addition, the external device 6 may indirectly acquire that the workpiece W conveyed by the conveyor 10 has reached a predetermined position through a detector (not shown), and the drawing control unit 40c may acquire a signal output from the external device 6 as a timing signal. The timing sensor 8 and the external device 6 are examples of a timing signal output unit that outputs a timing signal.

[0192] In the case where the distance sensor 31 is used as an optical timing sensor, the drawing control unit 40c receives a timing signal generated by the distance sensor 31. In this case, the drawing control unit 40c controls ink ejection from the ejection port 24a based on the drawing data stored in the storage unit 42 and the current relative position from the ejection port 24a of the print head 24 to each of the plurality of offset positions of the drawing data, using the timing signal generated by the distance sensor 31 as a reference based on the current relative position of the measurement value generated by the optical movement measuring sensor 30.

[0193] Since the sensor housing 32 is fixed to the main housing 25, the optical movement measuring sensor 30, the distance sensor 31, and the print head 24 are positioned and fixed. The relative positional relationship among the optical movement measuring sensor 30, the distance sensor 31, and the print head 24 is set to satisfy the following relationship: the optical movement measuring sensor 30 can receive light from the workpiece W from the time point when the timing signal generated by the distance sensor 31 is recognized until the drawing of the drawing information on the workpiece W is completed. The light from the workpiece W also includes reflected light that has been emitted to the workpiece W and reflected by the surface of the workpiece W.

[0194] In addition, the optical movement measuring sensor 30 of the sensor unit 3 can generate a timing signal indicating that the workpiece W has reached a predetermined position based on a change in the amount of light received. That is, when the transported workpiece W enters the light projection range from outside the light projection range of the optical movement measuring sensor 30, the amount of light received by the optical movement measuring sensor 30 changes. Since the timing of the change in the amount of light can be set to the timing when the workpiece W has reached the predetermined position, the optical movement measuring sensor 30 can generate a timing signal without using the timing sensor 8 and the external device 6. That is, the optical movement measuring sensor 30 is a part that receives light from the workpiece W, generates a measurement value related to the movement of the workpiece W in the transport direction based on the received light, and generates a timing signal indicating that the reference position of the workpiece W has been detected.

[0195] The drawing control unit 40c may acquire the timing signal generated by the optical movement measuring sensor 30 as the reference position information. In this case, the drawing control unit 40c acquires the current relative position of each of the plurality of offset positions from the ejection port 24a of the print head 24 to the drawing data based on the measurement value generated by the optical movement measuring sensor 30, using the timing signal generated by the optical movement measuring sensor 30 as a reference, and controls the ejection of ink from the ejection port 24a based on the acquired current relative position and the drawing data stored in the storage unit 42. Note that the drawing control unit 40c may also generate a timing signal at the timing at which the amount of light received by the optical movement measuring sensor 30 changes and acquire the timing signal.

[0196] The offset amount from the reference position of the workpiece W to the position where the above-mentioned drawing information is drawn may be defined as a first offset amount, and the offset amount from the reference position of the workpiece W to the ejection port 24a of the print head 24 may be defined as a second offset amount. The sensor housing 32 is positioned and fixed relative to the ejection port 24a of the print head 24 to correspond to the second offset amount. In this case, the drawing control unit 40c may determine the current relative position of each of the plurality of offset positions from the ejection port 24a of the print head 24 to the drawing data based on the first offset amount and the second offset amount.

[0197] (Drawing control based only on detection speed or distance)

[0198] Fig. 9 1 is a flowchart showing an example of a process of drawing control based only on the detection speed or distance detected by the sensor unit 3. This control is performed when the conveying speed (movement amount) of the workpiece W cannot be accurately acquired without the sensor unit 3. That is, when drawing is performed with a constant speed drawing setting assuming that the conveying speed of the workpiece W is constant, Figure 5 In the case of plotting data as shown, Fig.10 As shown, all time intervals from the first timing L1 to the seventh timing L7 are equal. Fig.11 As shown, when the conveying speed of the workpiece W is not constant by control using the encoder 7 or the like, the time intervals of the first timing L1 to the seventh timing L7 are not equal. In this way, the drawing control unit 40c controls the ink ejection from the ejection port 24a based on the current relative position from the ejection port 24a of the print head 24 to each of the plurality of offset positions of the drawing data and the drawing data.

[0199] Here, a case is assumed in which the conveying speed of the conveyor 10 is unstable or the conveying speed detected by the encoder 7 is unstable. In addition, a case is assumed in which the workpiece W is caught on a member such as a guide (not shown) in the middle of being conveyed by the conveyor 10, and the speed of the workpiece W is lower than the conveying speed of the conveyor 10. In addition, when the conveyor 10 starts and stops, there is an acceleration / deceleration area, and the speed of the workpiece W becomes unstable in the acceleration / deceleration area.

[0200] Regarding these, in the present embodiment, drawing control is performed based on the speed or distance obtained by the sensor unit 3 which is capable of directly detecting the conveying speed of the workpiece W, so that constant speed drawing and non-constant speed drawing can be performed by reflecting the actual conveying speed of the workpiece W without relying on the unstable conveying speed of the conveyor 10.

[0201] In the following, we will base on Fig. 9 After starting the drawing operation, in step SB1, the drawing control unit 40c obtains Fig. 8A The plotter 2 stores the drawing data set included in the job in step SA11 of the flowchart shown in FIG. In step SB2, the plotter 2 waits for the drawing to start, waits for a predetermined time, and then proceeds to step SB3. In step SB3, the plotter 2 determines whether a timing signal has been input. In a state where there is no input of a timing signal, the process proceeds to step SB2, and the plotter 2 continues to wait for the drawing to start.

[0202] The situation that the timing signal is input indicates that the workpiece W has reached the predetermined position, and the process proceeds to step SB4. In step SB4, the workpiece movement amount acquisition unit 40d acquires the movement amount of the workpiece W based on the measurement value output from the optical movement measuring sensor 30 of the sensor unit 3. The drawing control unit 40c calculates the current offset position relative to the reference position of the workpiece W based on the timing signal and the movement amount of the workpiece W. The movement amount of the workpiece W is always acquired.

[0203] In step SB5, the position of the ejection port 24a of the print head 24 relative to the current position of the workpiece W is determined based on the current offset position relative to the reference position of the workpiece W calculated in step SB4 and the drawing data stored in the storage unit 42. When the position of the ejection port 24a is not the position where ink should be ejected, the process proceeds to step SB4, and the current offset position relative to the reference position of the workpiece W is calculated. On the other hand, when the position of the ejection port 24a is the position where ink should be ejected, the process proceeds to step SB6, and the drawing control unit 40c controls the print head driving section 23 to eject ink from the ejection port 24a.

[0204] Thereafter, the process proceeds to step SB7, and it is determined whether all the drawing data have been drawn. When there is still drawing data that has not been drawn, the process proceeds to step SB4. On the other hand, when all the drawing data have been drawn, the drawing operation is ended, and the next workpiece W is waited for to be transferred.

[0205] (Control when detection accuracy decreases)

[0206] There may be a case where the detection accuracy of the optical movement measuring sensor 30 of the sensor unit 3 is low due to some reasons. For example, when dust adheres to the light receiving surface of the optical movement measuring sensor 30, there is a case where the amount of received light decreases so that a measurement value cannot be generated, and there is a case where the movement amount of the speckle pattern cannot be measured so that a measurement value cannot be generated. Fig.12 The illustrated flowchart shows control including processing in a case where the detection accuracy of the optical movement measuring sensor 30 is assumed to be low.

[0207] Fig.12 Steps SC1 to SC4 shown are similar to Fig. 9The steps SB1 to SB4 shown in FIG. 1 are the same. In step SC5, the detection accuracy of the optical movement measuring sensor 30 is determined. For example, in a case where the amount of received light of the optical movement measuring sensor 30 is below a threshold value, and in a case where the amount of movement of the speckle pattern cannot be measured, it is determined that the accuracy of the measurement value generated by the optical movement measuring sensor 30 is below a predetermined value and a drawing failure may occur, and the process proceeds to step SC6. In other cases, it is determined that the detection accuracy of the optical movement measuring sensor 30 is high and a drawing failure is unlikely to occur, and the process proceeds to step SC7.

[0208] In step SC6, the workpiece movement amount acquisition unit 40d acquires the movement amount based on the constant speed drawing setting or the encoder 7. The movement amount may also be acquired regardless of the encoder 7. That is, the user may operate the terminal side operation unit 5b or the operation display unit 43 according to the above. Fig. 8A The flowchart shown sets the conveying speed of the conveyor 10, and calculates the movement amount of the conveyor 10 for the workpiece W based on the set conveying speed. In this case, the terminal side operation unit 5b or the operation display unit 43 is a movement amount acquisition unit that acquires the movement amount caused by the conveyor 10. After the workpiece movement amount acquisition unit 40d acquires the movement amount based on the constant speed drawing setting or the encoder 7, the drawing control unit 40c calculates the current offset position relative to the reference position of the workpiece W based on the timing signal and the movement amount of the workpiece W.

[0209] In addition, in step SC6, processing for notifying the user of an error may also be performed. The error notification may include content prompting the user to perform maintenance, such as removing foreign matter attached to the sensor unit 3.

[0210] On the other hand, when the detection accuracy of the optical movement measuring sensor 30 is high and the process proceeds to step SC7, the workpiece movement amount acquisition unit 40d acquires the movement amount of the workpiece W based on the measurement value output from the optical movement measuring sensor 30 of the sensor unit 3. The drawing control unit 40c calculates the current offset position relative to the reference position of the workpiece W based on the timing signal and the movement amount of the workpiece W.

[0211] After step SC6 or step SC7, in step SC8, the position of the ejection port 24a of the print head 24 relative to the current position of the workpiece W is determined based on the current offset position relative to the reference position of the workpiece W calculated in step SC6 or step SC7 and the drawing data stored in the storage unit 42. When the position of the ejection port 24a is not the position where ink should be ejected, the process proceeds to step SC4. On the other hand, when the position of the ejection port 24a is the position where ink should be ejected, the process proceeds to step SC9. Steps SC9 and SC10 are respectively related to Fig. 9Steps SB6 and SB7 are the same.

[0212] In this way, when the accuracy of the measurement value generated by the optical movement measurement sensor 30 is below a predetermined value, the drawing control unit 40c can control the ink ejected from the ejection port 24a according to the movement amount and drawing data based on the constant speed drawing setting or the encoder 7, so that drawing can be performed based on the actual conveying speed (movement amount) of the workpiece W.

[0213] In this control, due to the processing of steps SC5 to SC7, switching occurs between the measurement value generated by the optical movement measuring sensor 30 and the value based on the constant speed drawing setting or the encoder 7. In this switching, a discontinuous change in the workpiece speed occurs due to a processing delay, so in order to prevent a strange feeling in the drawing result, complementary processing such as linear interpolation may be performed before and after the switching, and control that smoothly connects the control speeds before and after the switching may be performed.

[0214] (Control when the detection speed exceeds the threshold)

[0215] Fig.13 The control including the processing in the case where it is assumed that the detection speed detected by the sensor unit 3 may exceed the threshold value is shown. Fig. 8A The flowchart shown in the figure sets the conveying speed of the conveyor 10 in advance, and the normal drawing process is performed based on the constant speed drawing setting or the output from the encoder 7. For example, the conveying speed set based on the constant speed drawing setting has higher accuracy than the speed detected by the optical movement measuring sensor 30, and therefore, a favorable drawing state is obtained by performing the drawing process based on the constant speed drawing setting or the output from the encoder 7 in normal times.

[0216] However, for example, there may be a case where the workpiece W is caught on a certain member on the conveying surface 10a, so that the speed of the workpiece W cannot be detected. In this case, the speed detected by the optical movement measuring sensor 30 exceeds the preset speed threshold, and drawing is performed according to the speed detected by the optical movement measuring sensor 30 regardless of the constant speed drawing setting or the output from the encoder 7. Hereinafter, reference will be made to Fig.13 The flowchart shown describes the control when the speed detected by the optical movement measuring sensor 30 exceeds a threshold value.

[0217] Fig.13 Steps SD1 to SD4 shown are similar to Fig. 9The steps SB1 to SB4 shown in FIG. 1 are the same. In step SD5, the movement amount based on the constant speed drawing setting or the encoder 7 is acquired, and the movement is determined based on the acquired movement amount. That is, the movement amount acquired in step SD4 is compared with the movement amount acquired in step SD5, and it is determined whether the measurement value generated by the optical movement measurement sensor 30 exceeds a preset speed threshold. The threshold can be set to, for example, approximately plus or minus 10% of the conveying speed in the constant speed drawing setting.

[0218] When it is determined in step SD5 that the measurement value generated by the optical movement measuring sensor 30 does not exceed the threshold value, it is estimated that the workpiece W is not stuck, etc., and in this case, the processing proceeds to step SD6, and it is determined that the movement is within the specified error range. On the other hand, when it is determined in step SD5 that the measurement value generated by the optical movement measuring sensor 30 exceeds the threshold value, it is estimated that the workpiece W is stuck, etc., and in this case, the processing proceeds to step SD7, and it is determined that the movement exceeds the specified error range.

[0219] In step SD6, the workpiece movement amount acquisition unit 40d acquires the movement amount based on the constant speed drawing setting or the output from the encoder 7. After the workpiece movement amount acquisition unit 40d acquires the movement amount based on the constant speed drawing setting or the output from the encoder 7, the drawing control unit 40c calculates the current offset position relative to the reference position of the workpiece W based on the timing signal and the movement amount of the workpiece W.

[0220] In step SD7, the workpiece movement amount acquisition unit 40d acquires the movement amount of the workpiece W based on the measurement value output from the optical movement measuring sensor 30 of the sensor unit 3. The drawing control unit 40c calculates the current offset position relative to the reference position of the workpiece W based on the timing signal and the movement amount of the workpiece W. Steps SD8 to SD10 are the same as Fig.12 Steps SC8 to SC10 in are the same.

[0221] Therefore, the drawing control unit 40c determines in step SD5 whether the measurement value generated by the optical movement measuring sensor 30 exceeds the threshold value, and controls the ink ejected from the ejection port 24a according to the movement amount and the drawing data based on the constant speed drawing setting or the output from the encoder 7 until the measurement value exceeds the threshold value. On the other hand, when the measurement value generated by the optical movement measuring sensor 30 exceeds the threshold value as a result of the determination in step SD5, the drawing control unit 40c may control the ink ejected from the ejection port 24a according to the current offset position acquired based on the measurement value generated by the optical movement measuring sensor 30 and the drawing data.

[0222] In this control, due to the processing of steps SD5 to SD7, switching occurs between the measurement value generated by the optical movement measuring sensor 30 and the value based on the constant speed drawing setting or the output from the encoder 7. At the time of switching, a step change occurs from the setting value to the control value, so in order to prevent a strange feeling in the drawing result, complementary processing such as linear interpolation can be performed before and after the switching, and control that smoothly connects the control speed before and after the switching can be performed.

[0223] Furthermore, if the measurement value generated by the optical movement measuring sensor 30 jitters in the vicinity of a threshold value relative to a threshold value used as a determination reference for switching between the measurement value generated by the optical movement measuring sensor 30 and a value based on a constant speed drawing setting or an output from the encoder 7, a strange feeling occurs in the drawing result. In order to suppress the occurrence of the strange feeling, a hysteresis may be provided for the threshold value, and control may be performed so that switching due to the jitter does not occur frequently.

[0224] Furthermore, when it is determined in step SD5 that the measurement value generated by the optical movement measuring sensor 30 exceeds the threshold, control may be performed to notify the user by a warning or the like that the measurement value generated by the optical movement measuring sensor 30 exceeds the threshold without proceeding to step SC7 .

[0225] (Bump Correction)

[0226] For example, a conveyor with large vibrations (such as a roller conveyor) may be used as the conveyor 10. The workpiece W conveyed by the conveyor 10 has a vibration component perpendicular to the conveying direction of the workpiece W, and when it is assumed that the workpiece W is conveyed horizontally, the workpiece W vibrates irregularly in the up and down directions relative to the plotter 2. If the workpiece W has a vibration component perpendicular to the conveying direction, there is a possibility that the drawing quality is greatly deteriorated. In the present embodiment, the vibration of the workpiece W in the direction perpendicular to the conveying direction is referred to as "bumping". Bumping includes regular vibration and irregular vibration.

[0227] The inkjet printer 1 according to the present embodiment is configured to be able to perform jounce correction to suppress deterioration in drawing quality due to jounce of the workpiece W. In the jounce correction, the drawing control unit 40c controls the ink ejected from the ejection port 24a of the print head 24 based on the amount of movement of the workpiece W in the direction perpendicular to the conveying direction measured by the optical movement measuring sensor 30. Fig.14 The flowchart shown is used to describe the details of the bump correction.

[0228] Fig.14 Steps SE1 to SE3 shown are similar to Fig. 9Steps SB1 to SB3 shown are the same. In step SE4, the workpiece movement amount acquisition unit 40d acquires the movement amount of the workpiece W in the conveying direction (defined as the X direction) and the movement amount of the workpiece W in the direction perpendicular to the conveying direction (defined as the Y direction) based on the measurement value output from the optical movement measuring sensor 30 of the sensor unit 3. When the measurement value output from the optical movement measuring sensor 30 includes a component in the X direction and a component in the Y direction, the movement amount in the X direction and the movement amount in the Y direction can be acquired by performing a process of separating the component in the X direction and the component in the Y direction.

[0229] The drawing control unit 40c calculates the current offset position of the workpiece W in the X direction relative to the reference position based on the timing signal and the movement amount of the workpiece W in the X direction. At this time, the current offset position relative to the reference position of the workpiece W is also calculated in the Y direction. It should be noted that the X direction is the direction in which the plurality of ejection ports 24a are arranged, and in the case of horizontal transport, it is the vertical direction. In addition, the Y direction can also be referred to as a direction orthogonal to the array direction of the plurality of ejection ports 24a.

[0230] In step SE5, based on the current offset position of the workpiece W in the X direction relative to the reference position calculated in step SE4 and the drawing data stored in the storage unit 42, the position of the ejection port 24a of the print head 24 relative to the current position of the workpiece W is determined in the X direction of the workpiece W. When the position of the ejection port 24a in the X direction is not the position where ink should be ejected, the process proceeds to step SE4, and the current offset position of the workpiece W in the X direction relative to the reference position is calculated. On the other hand, when the position of the ejection port 24a in the X direction is the position where ink should be ejected, the process proceeds to step SE6.

[0231] In step SE6, the drawing data is shifted from the reference position in the Y direction by the shift amount. For example, Fig.15 The original data for the plotted data shown is Figure 5 The plotted data is shown. Fig.15 , a case where it is detected that the workpiece W has moved upward by one pixel from the reference position is shown at the ejection timing t3 and the ejection timing t5. In this case, the drawing data at each of the ejection timing t3 and the ejection timing t5 is shifted downward by one pixel in a direction that cancels the upward movement of the workpiece W. In addition, a case where it is detected that the workpiece W has moved upward by two pixels from the reference position is shown at the ejection timing t4. In this case, the drawing data at the ejection timing t4 is shifted downward by two pixels in a direction that cancels the upward movement of the workpiece W.

[0232] The offset amount and offset direction of the drawing data can be accurately acquired based on the measurement value output from the optical movement measurement sensor 30. In addition, although not shown, in the case where it is detected that the workpiece W has moved downward from the reference position at a certain ejection timing, the drawing data is offset upward so as to cancel the downward movement of the workpiece W. The offset of the data may also be referred to as the shift of the data. Fig.14 Steps SE7 and SE8 in Fig. 9 Steps SB6 and SB7 in are the same.

[0233] (including correction for rotational jitter)

[0234] Assume a case where the workpiece W conveyed by the conveyor 10 is displaced in the rotation direction around the horizontal axis when the workpiece W is viewed from the print head 24 side. In this case, with the inkjet printer 1 according to the present embodiment, it is possible to perform jitter correction including the rotation direction of the workpiece W, and to obtain favorable drawing quality. Fig.16 The flowchart shown in FIG. 1 describes the control contents of the pitch correction including the rotation direction. In order to perform the pitch correction including the rotation direction, a first optical movement measuring sensor 30A and a second optical movement measuring sensor 30B are provided, such as Fig.17 In the first example shown, the first optical movement measuring sensor 30A and the second optical movement measuring sensor 30B are identical.

[0235] exist Fig.17 In the first example shown, the first sensor unit 3A including the first optical movement measuring sensor 30A, the first sensor housing 32A and the distance sensor 31 and the second sensor unit 3B including the second optical movement measuring sensor 30B and the second sensor housing 32B are attached to the main housing 25 in a freely detachable manner. The first sensor housing 32A is arranged upstream of the print head 24 in the conveying direction. On the other hand, the second sensor housing 32B is arranged downstream of the print head 24 in the conveying direction. Therefore, the first optical movement measuring sensor 30A and the second optical movement measuring sensor 30B can be installed in a state separated from each other in the conveying direction.

[0236] exist Fig.18 In the second example shown, the first optical movement measuring sensor 30A and the second optical movement measuring sensor 30B are accommodated in one sensor housing 32. The first optical movement measuring sensor 30A is arranged upstream of the second optical movement measuring sensor 30B in the conveying direction. Also in the second example, the first optical movement measuring sensor 30A and the second optical movement measuring sensor 30B can be installed in a state separated from each other in the conveying direction as in the first example.

[0237] Fig.16Steps SF1 to SF3 in Fig. 9 The steps SB1 to SB3 shown in the figure are the same. In addition, in step SF4, the workpiece movement amount acquisition unit 40d acquires the movement amount of the workpiece W in the X direction and the movement amount of the workpiece W in the Y direction based on the measurement value output from the first optical movement measuring sensor 30A, and the workpiece movement amount acquisition unit 40d acquires the movement amount of the workpiece W in the X direction and the movement amount of the workpiece W in the Y direction based on the measurement value output from the second optical movement measuring sensor 30B. The drawing control unit 40c calculates the current offset position of the workpiece W in the X direction relative to the reference position based on the timing signal and the movement amount of the workpiece W in the X direction.

[0238] In step SF5, based on the current offset position of the workpiece W in the X direction relative to the reference position calculated in step SF4 and the drawing data, the position of the workpiece W relative to the ejection orifice 24a of the print head 24 is calculated in the X direction of the workpiece W. At this time, the position of the workpiece W relative to the ejection orifice 24a of the print head 24 is also calculated in the Y direction. In addition, the rotation direction and the rotation amount (θ) of the workpiece W around the horizontal axis are calculated based on the measurement value output from the first optical movement measuring sensor 30A and the measurement value output from the second optical movement measuring sensor 30B.

[0239] In step SF6, based on the current offset position of the workpiece W in the X direction relative to the reference position calculated in step SF5 and the drawing data stored in the storage unit 42, the position of the ejection port 24a of the print head 24 relative to the current position of the workpiece W is determined in the X direction of the workpiece W. In the case where the position of the ejection port 24a in the X direction is not the position where ink should be ejected, the process proceeds to step SF4. On the other hand, when the position of the ejection port 24a in the X direction is the position where ink should be ejected, the process proceeds to step SF7.

[0240] In step SF7, the drawing data is offset from the reference position by the amount of movement and rotation in the Y direction. The offset in the Y direction is performed as described above. The offset in the rotation direction may be performed in the same manner as the offset in the Y direction, and the drawing data is offset in a direction that cancels the rotation of the workpiece W. In step SF7, control is performed so that the already drawn drawing data is not drawn again. Fig.16 Steps SF8 and SF9 in Fig. 9 Steps SB6 and SB7 are the same.

[0241] When the movement amount in the X direction and the movement amount in the Y direction (vibration speed) exceed the correctable critical speed, a process of not executing the pitch correction or a process of notifying the user of an error may be performed.

[0242] For example, among the plurality of ejection ports 24a arranged in the up-down direction of the print head 24, a predetermined number of ejection ports 24a on the upper side and a predetermined number of ejection ports 24a on the lower side may be set as the ejection ports 24a for the correction margin. In this case, when the jounce correction is not performed, the drawing process is performed only by the ejection ports 24a other than the ejection ports 24a for the correction margin (i.e., the ejection ports 24a at the middle portion in the up-down direction). On the other hand, when the jounce correction is required, the drawing may be performed using the predetermined number of upper ejection ports 24a including the upper end (upper correction margin) and the predetermined number of lower ejection ports 24a including the lower end (lower correction margin) to eliminate the vibration of the workpiece W. In this case, when a large vibration exceeding the upper correction margin and the lower correction margin occurs in the workpiece W, a process of not performing the jounce correction or a process of notifying the user of an error is performed.

[0243] In addition, the user may be allowed to set the amount of vibration to be subjected to the jitter correction. Since there is a response delay due to the jitter correction, it is assumed that when the measured amount of vibration is small, the vibration amount is increased (contrary to expectation) by performing the jitter correction. Therefore, when the measured amount of vibration is below a predetermined value, an offset process that offsets the jitter correction may be performed.

[0244] (To deal with the inclined line)

[0245] The inkjet printer 1 of the present embodiment is configured to supply ink to the print head 24 using a hydraulic head pressure. Therefore, the structure can be simplified, but the ink level in the sub-tank 21a needs to fall within a predetermined tilt range relative to the horizontal plane (within a few degrees of tilt relative to the horizontal plane), and there are restrictions on the installation of the plotter 2. In addition, the posture of the sub-tank 21a that supplies ink to the print head 24 has a tilt tolerance in the positional relationship with the supply port on the print head 24 side.

[0246] Meanwhile, there is a case where the conveying direction of the conveyor 10 is inclined. Examples of this case include an inclination that descends toward the downstream side in the conveying direction and an inclination that ascends toward the downstream side in the conveying direction. In the case of installing the plotter 2 on such an inclined line, if the inclination of the inclined line exceeds the specified inclination of the plotter 2, the plotter 2 cannot be installed, and the application range of the plotter 2 is limited.

[0247] On the other hand, in the inkjet printer 1 according to the present embodiment, the plotter 2 can be installed within a specified slope and can cope with the sloped line, so that the sloped line handling control can be performed. Fig.19 The flowchart shown is used to describe the details of the tilt line response control.

[0248] Steps SG1 to SG4 and Fig.14Steps SE1 to SE4 shown are the same. In step SG5, the conveying direction identification unit 40g determines the inclination direction and inclination angle θ of the conveying surface 10a of the conveyor 10 based on the movement amount in the X direction and the movement amount in the Y direction of the workpiece W acquired in step SG4. The inclination direction and inclination angle θ of the conveying surface 10a of the conveyor 10 match the conveying direction of the workpiece W. The inclination direction and inclination angle θ can be calculated by atan(Y / X), and the calculated inclination direction and inclination angle θ are temporarily stored. As the inclination angle θ, a measured value in a previous drawing can be used. In addition, the calculated inclination angle θ can be corrected later.

[0249] In step SG6, the drawing data is configured so that drawing in a direction parallel to the tilt, ie, as intended, is performed on the workpiece W by performing affine transformation on the drawing data based on the conveying direction identified by the conveying direction identifying unit 40g.

[0250] In step SG7 , similarly to step SG4 , the workpiece movement amount acquisition unit 40 d acquires the movement amount of the workpiece W in the X direction and the movement amount of the workpiece W in the Y direction based on the measurement value output from the optical movement measuring sensor 30 .

[0251] In step SG8, ​​the position of the ejection port 24a of the print head 24 relative to the current position of the workpiece W is determined based on the current offset position relative to the reference position of the workpiece W calculated in step SG7 and the drawing data. When the position of the ejection port 24a is not the position where the ink should be ejected, the process proceeds to step SG7. On the other hand, when the position of the ejection port 24a is the position where the ink should be ejected, the process proceeds to step SG9. In step SG9, when the conveying direction identified by the conveying direction identification unit 40g is inclined relative to the horizontal plane, the drawing control unit 40c controls the ink ejected from the ejection port 24a so that information such as a character string or an image is drawn parallel to the conveying direction. Steps SG10 and SG11 are performed together. Fig. 9 This example is suitable when the mounting reliability of the plotter 2 relative to the conveyor 10 is low.

[0252] (Get the tilt angle of the workpiece during installation)

[0253] It is also possible to obtain the inclination angle of the workpiece W during the conveyance by the conveyor 10 when the plotter 2 is installed. This example is suitable when it is desired to avoid the measurement error of the sensor unit 3 or when the installation reliability of the plotter 2 relative to the conveyor 10 is high. Fig. 20 A process of acquiring the tilt angle of the workpiece W relative to the plotter 2 when the plotter 2 is installed is described.

[0254] In step SH1, the control section 40 waits for the workpiece W to pass through the front of the sensor unit 3. The passage of the workpiece W may be detected by the optical movement measuring sensor 30 of the sensor unit 3, or may be detected by the encoder 7. In step SH2, it is determined whether a drawing start trigger has been input. When the drawing start trigger has not been input, the process returns to step SH1, and when the drawing start trigger has been input, the process proceeds to step SH3.

[0255] In step SH3, the workpiece movement amount acquisition unit 40d acquires the movement amount of the workpiece W in the X direction and the movement amount of the workpiece W in the Y direction based on the measurement value output from the optical movement measuring sensor 30. In step SH4, the conveying direction recognition unit 40g determines the inclination direction and the inclination angle θ of the conveying surface 10a of the conveyor 10 based on the movement amount in the X direction and the movement amount in the Y direction of the workpiece W acquired in step SH3. Therefore, the inclination direction of the workpiece W during conveyance can be acquired as a correction value at the time of installation and stored in the storage unit 42 or the like. When performing affine transformation on the drawing data, the inclination angle acquired in this process is used.

[0256] (When the tilt angle of the workpiece exceeds the allowable value during transfer)

[0257] Fig.21 FIG. 2 shows a process for processing when it is detected that the inclination angle θ of the workpiece W exceeds the preset allowable value of the inclination angle. Steps SI1 to SI6 are respectively related to Fig.19 Steps SG1 to SG6 are the same.

[0258] In step SI7, the tilt angle θ determined in step SI5 is acquired, and it is determined whether the acquired tilt angle θ exceeds a threshold value (permissible value). When it is determined in step SI7 that the tilt angle θ exceeds the threshold value, the process proceeds to step SI8, and the user is notified of a tilt angle error. When a tilt angle error is notified, drawing can be continued or stopped. On the other hand, when it is determined in step SI7 that the tilt angle θ does not exceed the threshold value, the process proceeds to step SI4. Steps SI9 to SI12 are respectively related to Fig.19 Steps SG7 to SG10 are the same.

[0259] (Installation example)

[0260] exist Fig.17In the first example shown, as described above, the print head 24 is arranged between the first optical movement measuring sensor 30A and the second optical movement measuring sensor 30B. That is, the second optical movement measuring sensor 30B is additionally provided on the downstream side of the print head 24 in the conveying direction of the workpiece W, so that the dead zone at the very end in the conveying direction of the workpiece W can be eliminated. However, due to the influence of the ink mist or ink droplets of splashed ink on the downstream side in the conveying direction of the workpiece W, the detection failure of the second optical movement measuring sensor 30B may occur, so the influence of the ink mist or ink droplets of splashed ink can be reduced by setting the detection surface of the second optical movement measuring sensor 30B to positive pressure using a positive pressure generator such as air purge.

[0261] exist Fig.18 In the second example shown, the first optical movement measuring sensor 30A, the distance sensor 31, the second optical movement measuring sensor 30B, and the print head 24 are arranged in this order from the upstream side in the conveying direction of the workpiece W. With such an array, the measurement of the movement amount of the workpiece W can be started in a state where the first optical movement measuring sensor 30A outputs a valid measurement value, and a dead zone (a portion that cannot be measured by the optical movement measuring sensor) at the terminal end of the workpiece W in the conveying direction can be minimized.

[0262] Fig. 22 3 is a view showing a third example in which a first optical movement measuring sensor 30A and a second optical movement measuring sensor 30B are provided. In the third example, the first optical movement measuring sensor 30A and the second optical movement measuring sensor 30B are accommodated in one sensor housing 32. The first optical movement measuring sensor 30A is disposed upstream of the second optical movement measuring sensor 30B in the conveying direction. The sensor housing 32 is attached to the downstream side of the main housing 25 in the conveying direction of the workpiece W. Therefore, the first optical movement measuring sensor 30A and the second optical movement measuring sensor 30B are arranged downstream of the print head 24 in the conveying direction of the workpiece W.

[0263] When the first optical movement measuring sensor 30A, the second optical movement measuring sensor 30B, and the distance sensor 31 are arranged on the downstream side of the print head 24 as in the third example, drawing can be performed without generating a dead zone to the most terminal end in the conveying direction of the workpiece W. However, in order to suppress detection failure due to ink droplets or the like, it is preferable to set the detection surfaces of the first optical movement measuring sensor 30A, the second optical movement measuring sensor 30B, and the distance sensor 31 to a positive pressure using a positive pressure generator.

[0264] exist Fig. 22In the case shown, the sensor housing 32 is detachably attached to the main housing 25 at a position deviated from the downstream side (one side) in the conveying direction of the workpiece W. Figure 3 and Fig.18 In the case shown, the sensor housing 32 is detachably attached to the main housing 25 at a position deviated from the upstream side (the other side) along the conveying direction of the workpiece W. In this way, the sensor housing 32 according to the present embodiment is detachably attached to the main housing 25 at a first position deviated from one side and a second position deviated from the other side along the conveying direction of the workpiece W. The user may freely select the first position or the second position to which the sensor housing 32 is to be attached according to the workpiece W, drawing contents, the structure of the conveyor 10, the line configuration, etc. The height of the sensor housing 32 at the first position and the second position can be adjusted.

[0265] Fig.23 1 is a view showing a fourth example in which the first optical movement measuring sensor 30A and the second optical movement measuring sensor 30B are provided. In this fourth example, the first optical movement measuring sensor 30A, the second optical movement measuring sensor 30B, and the distance sensor 31 are attached to the upper side of the print head 24. Therefore, the dead zones at the downstream end and the upstream end in the conveying direction of the workpiece W can be minimized.

[0266] In addition, although not shown, the first optical movement measuring sensor 30A, the second optical movement measuring sensor 30B, and the distance sensor 31 may be attached on the lower side of the print head 24. Also in this case, the dead zone at the downstream end and the upstream end of the workpiece W in the conveying direction can be minimized. In addition, the optical movement measuring sensor and the distance sensor may be attached to all of the upstream side, downstream side, upper side, and lower side of the print head 24, or may be attached to any two or three of the upstream side, downstream side, upper side, and lower side of the print head 24. Furthermore, both or one of the optical movement measuring sensor and the distance sensor may be embedded in the print head 24. In addition, one of the measuring sensor and the distance sensor may be embedded in the print head 24, and the other may be provided outside the print head 24.

[0267] In addition, despite Figure 3 The examples of performing drawing on the side surface of the workpiece W are shown in the figure, but the present invention is not limited thereto and can also be applied to the case where drawing is performed on the top surface of the workpiece W and the case where drawing is performed on the lower surface of the workpiece W. In the case of drawing on the upper surface or the lower surface of the workpiece W, it is sufficient to install the plotter 2 so that the ejection port 24a of the print head 24 is opposite to the surface where drawing is to be performed.

[0268] Fig.241 is a plan view showing the inkjet printer 1 during operation. As shown in the figure, the sensor housing 32 is positioned and fixed relative to the print head 24 so that the front surface 32a and the window 32b of the sensor housing 32 are at a certain distance from the print head 24 ( Fig.24 In other words, the optical movement measuring sensor 30 is positioned and fixed relative to the print head 24 so that the window 32 b is at a position retracted from the print head 24, and the optical movement measuring sensor 30 is positioned and fixed relative to the print head 24 through the sensor housing 32. Note that the window 32 b may be positioned on the same plane as the distal end of the main housing 25.

[0269] Here, a case where drawing is performed on the side surface of the workpiece W is assumed. In the case where drawing is performed on the side surface of the workpiece W, by retracting the front surface 32a and the window 32b of the sensor housing 32 from the print head 24, the distance D2 between the side surface of the workpiece W and the front surface 32a (window 32b) of the sensor housing 32 is set to be longer than the distance D1 between the side surface of the workpiece W and the distal end of the print head 24. Therefore, since the front surface 32a of the sensor housing 32 can be separated from the face of the workpiece W on which the particulate ink falls, ink droplets splashed from the workpiece W and droplets due to splashing are less likely to adhere to the front surface 32a of the sensor housing 32. In addition, the workpiece W is less likely to collide with the sensor housing 32, and the distance between the print head 24 and the workpiece W is not affected by the installation position of the sensor housing 32, so that the range (drawing distance range) of the plotter 2 can be fixed to the maximum value.

[0270] Note that the sensor housing 32 may be positioned and fixed relative to the print head 24 so that the front surface 32 a and the window 32 b of the sensor housing 32 are at a position advanced from the print head 24 (a position closer to the workpiece W). In addition, the front surface 32 a and the window 32 b of the sensor housing 32 and the print head 24 may be at the same position in the distance direction from the print head 24.

[0271] Fig.25 1 is a plan view showing an inkjet printer 1 provided with a first optical movement measuring sensor 30A and a second optical movement measuring sensor 30B during operation. The first optical movement measuring sensor 30A and the second optical movement measuring sensor 30B are identical. The measuring range of the first optical movement measuring sensor 30A is indicated as a first measuring range 110, and the measuring range of the second optical movement measuring sensor 30B is indicated as a second measuring range 120. In addition, the measuring light projected from the distance sensor 31 is denoted by reference numeral 130.

[0272] The depth of field of the light receiving unit 30b included in each of the first optical movement measuring sensor 30A and the second optical movement measuring sensor 30B is indicated by reference numeral D3. The lower limit (the side close to the sensor) of the movement amount measurable range of the first optical movement measuring sensor 30A is determined by the measurable distance relative to the white workpiece having a high reflectivity, and the upper limit (the side far from the sensor) is determined by the measurable distance relative to the black workpiece having a low reflectivity. At a distance below the lower limit of the movement amount of the measurable range of the first optical movement measuring sensor 30A, the amount of light on the light receiving unit 30b is saturated relative to the white workpiece, the speckle contrast cannot be sufficiently obtained, and the movement amount cannot be measured. In addition, at a distance above the upper limit of the first optical movement measuring sensor 30A or the movement amount measurable range, the amount of light on the light receiving unit 30b is insufficient due to the small amount of light received, the speckle contrast is buried in the noise component, and the movement amount cannot be measured. Here, as the white workpiece and the black workpiece, based on JCS M001:2000, code number D250 (color name: white) is used for the white workpiece, and code number D260 (color name: black) is used for the black workpiece.

[0273] exist Fig.25 , the drawing distance range of the print head 24 is indicated by reference symbol D4. The depth of field D3 of the light receiving unit 30b is wider than the drawing distance range D4 of the print head 24, and the depth of field D3 of the light receiving unit 30b includes the drawing distance range D4 of the print head 24.

[0274] That is, since the light receiving unit 30b is fixed to the sensor housing 32, the position of the light receiving unit 30b is determined by attaching the sensor housing 32 to the main housing 25. In this example, the optical movement measuring sensor 30 is fixed to the print head 24 through the sensor housing 32 so that the depth of field of the light receiving unit 30b in the distance direction from the print head 24 includes the drawing distance range of the print head 24, and the sensor housing 32 serves as a fixing portion configured to position and fix the optical movement measuring sensor 30 relative to the print head 24. Note that the fixing portion may be a bracket or the like configured separately from the sensor housing 32, or may include a fastening member such as a bolt or a screw.

[0275] In addition, the distance sensor 31 is positioned and fixed relative to the print head 24 so that the measurement range of the distance sensor 31 (for convenience, indicated by the same reference numeral D3 as the measurement range of the light receiving unit 30b) includes the drawing distance range of the print head 24 in the distance direction from the ejection port 24a of the print head 24. When the distance between the print head 24 and the workpiece W is set to the drawing distance range, favorable drawing can be performed without disturbing the drawing. That is, the distance between the print head 24 and the workpiece W for preventing the drawing disturbance from exceeding the allowable value of the drawing quality is the drawing distance range. Note that the measurement range of the distance sensor 31 and the depth of field of the light receiving unit 30b may be different.

[0276] As shown in the figure, the first optical movement measuring sensor 30A and the second optical movement measuring sensor 30B are arranged to be spaced apart from each other in the conveying direction of the workpiece W, and the distance sensor 31 is arranged between the first optical movement measuring sensor 30A and the second optical movement measuring sensor 30B, thereby preventing the measurement failure of the end of the workpiece W in the conveying direction. That is, Fig.25 As shown, in a case where the first optical movement measuring sensor 30A measures the workpiece W and the second optical movement measuring sensor 30B does not measure the workpiece W, it can be seen that the upstream end of the workpiece W in the conveying direction is measured by the distance sensor 31. On the other hand, in a case where the first optical movement measuring sensor 30A does not measure the workpiece W and the second optical movement measuring sensor 30B measures the workpiece W, it can be seen that the downstream end of the workpiece W in the conveying direction is measured by the distance sensor 31.

[0277] exist Fig.25 , as shown by the dotted line, the sensor housing 32 that accommodates the first optical movement measuring sensor 30A and the second optical movement measuring sensor 30B can be attached to the downstream side of the main housing 25. The sensor housing 32 is configured to be detachably attached to the print head 24 on the upstream side and the downstream side in the conveying direction of the workpiece W. The sensor housing 32 is positioned and fixed to the print head 24 on both the upstream side and the downstream side in the conveying direction of the workpiece W. Note that the sensor housing 32 may be positioned and fixed to the print head 24 only on the upstream side or only on the downstream side in the conveying direction of the workpiece W, without being limited thereto.

[0278] Figure 26 to Figure 28 FIG. 4 shows a specific example of a sensor unit 3 including a first optical movement measuring sensor 30A and a second optical movement measuring sensor 30B. Figure 26 to Figure 28 The posture shown in Figure 26 to Figure 28 The top of the figure is the top posture when attached) is attached to the upstream side of the main shell 25. Fig.29 and Fig.30As shown, the sensor housing 32 of the sensor unit 3 is detachably attached to the print head 24 in an inverted posture.

[0279] In addition, if Fig.31 As shown, the optical movement measuring sensor 30 and the distance sensor 31 can be accommodated in the main housing 25 without providing the sensor housing 32 for accommodating the optical movement measuring sensor 30 and the distance sensor 31 outside the main housing 25. For example, an area for accommodating the optical movement measuring sensor 30 and the distance sensor 31 in the main housing 25 may be provided, and the optical movement measuring sensor 30 and the distance sensor 31 or the sensor housing 32 may be accommodated in the area. In addition, when the light-transmitting portion 25B that transmits the measuring light of the optical movement measuring sensor 30 and the measuring light of the distance sensor 31 is provided in the portion of the main housing 25 opposite to the workpiece W being conveyed, measurement by the optical movement measuring sensor 30 and the distance sensor 31 is possible.

[0280] like Fig.32 As shown, the sensor housing 32 can be mounted at a different location from the main housing 25. Fig.32 In the example shown, the sensor housing 32 is installed above the workpiece W, and the workpiece W can be measured from above. When the sensor housing 32 is installed above the workpiece W in a line where a workpiece W with a high height and a workpiece W with a low height coexist, both the workpiece W with a high height and the workpiece W with a low height can be accurately measured using the optical movement measurement sensor 30 having a large depth of field. Note that in the case of this attachment mode, the distance between the workpiece W and the print head 24 cannot be measured by the distance sensor 31, and therefore, the distance sensor 31 is attached separately to the print head 24 side.

[0281] Fig.33 1 is a plan view showing an example of providing the pressing mechanism 130 of the print head 24. Although the sensor housing 32 is shown by a dotted line, the position of the sensor housing 32 is not limited to the shown position and may be on the upstream side or upper side of the main housing 25, for example.

[0282] The attachment portion 25A is provided on the upstream side of the main housing 25. The pressing mechanism 130 includes a positioning member 131 positioned and fixed to the conveyor 10 and a coil spring 132 as an elastic body. The positioning member 131 is provided with a rod 131a extending in a horizontal direction perpendicular to the conveying direction. The attachment portion 25A of the main housing 25 is supported by the rod 131a so as to be able to slide in a horizontal direction perpendicular to the conveying direction.

[0283] The rod 131a is inserted into the coil spring 132, and the contraction direction of the coil spring 132 is consistent with the axial direction of the rod 131a. The attachment portion 25A of the main housing 25 is arranged on the side closer to the workpiece W than the coil spring 132, whereby the coil spring 132 always presses the attachment portion 25A of the main housing 25 in the direction of ejecting ink.

[0284] The workpiece guide 133 is provided on the upstream side of the main housing 25. Fig.33 is conveyed closer to the upper side, the workpiece W abuts against the workpiece guide 133, and Fig.33 The upward force in the workpiece guide 133 acts on the workpiece guide 133. When the coil spring 132 is contracted by this force, the print head 24 is Fig.33 The print head 24 moves upward in the process, but the distance between the print head 24 and the workpiece W is maintained at a predetermined distance. Therefore, even if the workpiece W is conveyed closer Fig.33 On the upper side, interference-free drawing can also be performed.

[0285] (including multiple nozzles)

[0286] Although the above-described inkjet printer 1 includes one print head 24 , the number of the print head 24 is not limited to one, and an inkjet printer 1 including a plurality of print heads 24 is also included in the embodiment of the present invention.

[0287] That is, although not shown, the inkjet printer 1 includes, for example, a first print head (first nozzle) and a second print head (second nozzle). The first print head has a plurality of ejection ports arranged in a predetermined direction. In addition, the second print head also has a plurality of ejection ports arranged in a predetermined direction. The number of ejection ports of the first print head and the number of ejection ports of the second print head may be the same or different.

[0288] The first print head is disposed in the first housing. The second print head is disposed in the second housing, which can be arranged separately from the first housing. That is, the first housing and the second housing are separated and can therefore be arranged at mutually different points, and drawing can be performed on different parts of the workpiece W.

[0289] The drawing data stored in the storage unit 42 includes the drawing data of the first nozzle and the drawing data of the second nozzle. The drawing data of the first nozzle and the drawing data of the second nozzle may be different or the same. The drawing control unit 40c controls the ink ejection from the plurality of ejection ports formed in the first nozzle based on the current offset position and the drawing data of the first nozzle, and controls the ink ejection from the plurality of ejection ports formed in the second nozzle based on the current offset position and the drawing data of the second nozzle. Therefore, it is possible to perform drawing on a plurality of points of the workpiece W using one inkjet printer 1.

[0290] (Control in the case where an optical movement measuring sensor is used as a timing sensor)

[0291] The optical movement measurement sensor 30 may be used as a timing sensor to detect that the workpiece W conveyed by the conveyor 10 has reached a predetermined position. Fig.34 The flowchart shown describes in detail the control in the case where the optical movement measuring sensor 30 is used as a timing sensor.

[0292] Fig.34 Steps SJ1 and SJ2 shown are similar to Fig. 9 Steps SB1 and SB2 shown are the same. In step SJ3, the drawing start timing acquisition unit 40f determines whether the amount of received light of the optical movement measuring sensor 30 is sufficient. The case of "sufficient amount of received light" is a case where the optical movement measuring sensor 30 can generate highly accurate measurement values ​​(normal measurement values) to the extent that it can be used as a timing sensor. When it is determined in step SJ3 that the amount of received light of the optical movement measuring sensor 30 is sufficient, the processing proceeds to step SJ4. On the other hand, in the case where the amount of received light of the optical movement measuring sensor 30 is not sufficient and it is impossible to use it as a timing sensor, the processing proceeds to step SJ2.

[0293] In step SJ4, the drawing start timing acquisition unit 40f determines whether the amount of the speckle pattern generated by the optical movement measuring sensor 30 is sufficient. The case where the "amount of the speckle pattern is sufficient" is a case where the optical movement measuring sensor 30 can generate highly accurate measurement values ​​to the extent that it can function as a timing sensor. In step SJ4, when it is determined that the amount of the speckle pattern generated by the optical movement measuring sensor 30 is sufficient, the process proceeds to step SJ5. On the other hand, in the case where the amount of the speckle pattern generated by the optical movement measuring sensor 30 is not sufficient and it is not possible to function as a timing sensor, the process proceeds to step SJ2.

[0294] In step SJ5, since the amount of received light of the optical movement measuring sensor 30 is sufficient and the amount of the speckle pattern is also sufficient, the drawing start timing acquisition unit 40f determines the measurement value output from the optical movement measuring sensor 30 as a signal of the timing sensor being turned on (ON). Thereafter, the process proceeds to step SJ6. Steps SJ6 to SJ9 are similar to the steps in step SJ6. Fig. 9 Steps SB4 to SB7 shown are the same.

[0295] That is, the timing at which the optical movement measuring sensor 30 detects the workpiece W and starts generating normal measurement values ​​is set to the pseudo-timing sensor on timing, and the drawing operation is started. Note that when the optical movement measuring sensor 30 detects both edges of the workpiece W in the conveying direction, detection noise is generated, and if the noise may be a problem, noise removal processing may be applied.

[0296] (Exception handling)

[0297] As described above, the plotter 2 plots the workpiece W conveyed in front of the plotter 2 according to the conveying speed of the workpiece W. In the case where the conveying speed of the workpiece W is a constant speed, constant speed plotting can be performed. In the case where the conveying speed is not constant, plotting can be performed by acquiring the conveying speed using the encoder 7 and calculating the workpiece speed based on this encoder signal (encoder plotting). In any of these systems, the plotting start timing can be determined by the timing sensor 8, the optical movement measuring sensor 30, etc.

[0298] However, when constant speed drawing is performed, it is impossible to know whether the conveying speed of the workpiece W is actually constant, so even if interference occurs in drawing due to the execution of constant speed drawing, the cause of the interference is not found. In addition, in the case of encoder drawing, even if interference occurs in drawing due to the encoder 7 slipping, the workpiece W getting stuck, etc., it is difficult to detect the interference of drawing. In addition, when the detection surface of the timing sensor 8 is contaminated with dust or particulate ink, it is difficult to determine the reliability of the timing sensor 8, and regular maintenance of the timing sensor 8 is required. In addition, when the bumping of the workpiece W occurs, there is no problem in the case of performing the bumping correction, but there is no way to evaluate whether the bumping of the workpiece W affects the drawing quality in the case of not performing the bumping correction. In addition, when an angle deviation occurs between the plotter 2 and the conveyor 10, there is no problem if the tilt correction is performed, but the angle deviation cannot be known if the tilt correction is not performed. In addition, in the case where the workpiece W is a corrugated cardboard, when the baffle of the corrugated cardboard is peeled off, etc., the timing sensor 8 that may have detected the baffle erroneously operates by considering it as the arrival of the workpiece W, thereby causing an error in the drawing start position. Although there are various causes of drawing failure in this way, it is difficult to prevent drawing failure in advance in conventional constant speed drawing and encoder drawing, and therefore, it is necessary to confirm the drawing quality with a camera or a person, which takes time and effort.

[0299] In the inkjet printer 1 of this embodiment, the reliability of the measurement performed by the optical movement measurement sensor 30 is evaluated, and based on the evaluation result, abnormal processing is performed when the reliability of the measurement performed by the optical movement measurement sensor 30 is low, thereby suppressing the occurrence of drawing failures due to the above-mentioned various reasons.

[0300] The details will be described below. The control section 40 of the controller 4 includes an evaluation unit 40h and an exception processing unit 40i which are composed of hardware and software. For convenience, the evaluation unit 40h and the exception processing unit 40i are separated, but can be integrated in terms of hardware.

[0301] The evaluation unit 40h is a part that evaluates the reliability of the measurement performed by the optical movement measuring sensor 30. Specifically, the evaluation unit 40h can evaluate the reliability based on the amount of received light received by the optical movement measuring sensor 30. Since a highly accurate measurement value can be generated if the amount of received light received by the optical movement measuring sensor 30 is sufficient, in this case, the evaluation unit 40h evaluates that the reliability of the measurement performed by the optical movement measuring sensor 30 is high. On the other hand, if the amount of received light received by the optical movement measuring sensor 30 is insufficient, the accuracy of the measurement value is reduced, or the measurement value cannot be generated. In this case, the evaluation unit 40h evaluates that the measurement reliability of the optical movement measuring sensor 30 is low. When the amount of received light received by the optical movement measuring sensor 30 exceeds a predetermined range (for example, is less than a predetermined value), the abnormality processing unit 40i determines that the reliability does not meet a predetermined standard and performs abnormality processing. An example of the reason why the amount of light received by the optical movement measuring sensor 30 is insufficient may include a case where the detection surface of the optical movement measuring sensor 30 is contaminated with dust or particulate ink.

[0302] In addition, the evaluation unit 40h can evaluate the reliability based on whether the measurement of the optical movement measuring sensor 30 can be performed. When it is possible to perform the measurement of the optical movement measuring sensor 30, the evaluation unit 40h evaluates that the reliability of the measurement of the optical movement measuring sensor 30 is high. On the other hand, when it is impossible to perform the measurement of the optical movement measuring sensor 30, the evaluation unit 40h evaluates that the reliability of the measurement of the optical movement measuring sensor 30 is low. When it is impossible to perform the measurement of the optical movement measuring sensor 30, the abnormality processing unit 40i determines that the reliability does not meet the predetermined standard and performs abnormality processing. In this way, the abnormality processing unit 40i is a part that performs abnormality processing when the reliability evaluated by the evaluation unit 40h does not meet the predetermined standard.

[0303] The evaluation elements of the evaluation unit 40h are not limited to the amount of received light of the optical movement measuring sensor 30 and the possibility of the optical movement measuring sensor 30 to measure the amount of received light, and examples thereof may include the distance to the workpiece W in the ejection direction of the print head 24, the movement of the workpiece W in the conveying direction, the amount of movement of the workpiece W in the direction perpendicular to the conveying direction, the amount of movement in the direction inclined with respect to the conveying direction of the workpiece W, the amount of received light of the distance sensor 31, the recognition rate of the speckle pattern of the optical movement measuring sensor 30, the contrast of the drawing target generated according to the amount of light received from the workpiece W as the drawing target, the quality of the speckle pattern generated according to the characteristics of the surface shape of the workpiece W, the distance the workpiece W is conveyed between the turning on and off of the drawing start timing signal, and the difference with the input of the encoder 7.

[0304] When the reliability is evaluated based on the distance to the workpiece W in the ejection direction of the print head 24, the reliability of printing is evaluated as low in the case where it can be determined that the workpiece W is located at a position farther than the drawable distance, and the reliability is evaluated as high in the case where it can be determined that the workpiece W is located within the distance that can be drawn. When the reliability is evaluated based on the movement of the workpiece W in the conveying direction, it can be determined whether the workpiece W is accelerating / decelerating or stopped. For example, in the case where it can be determined that the workpiece W is accelerating / decelerating, the reliability is evaluated as high, and in the case where it can be determined that the workpiece W is stopped, the reliability is evaluated as low.

[0305] When the reliability is evaluated based on the amount of movement of the workpiece W in the direction perpendicular to the conveying direction, it can be estimated that bumping occurs when the amount of movement of the workpiece W in the direction perpendicular to the conveying direction is a predetermined value or more, and in this case, the reliability is evaluated to be low. When the amount of movement of the workpiece W in the direction perpendicular to the conveying direction is less than a predetermined value, the reliability is evaluated to be high.

[0306] When the reliability is evaluated based on the amount of movement of the workpiece W in the direction inclined relative to the conveying direction, it is possible to determine whether an angle deviation occurs between the plotter 2 and the conveyor 10, and when the angle deviation occurs between the plotter 2 and the conveyor 10 is a predetermined value or more, it is evaluated that the reliability is low, and when the angle deviation occurs between the plotter 2 and the conveyor 10 is less than the predetermined value, it is evaluated that the reliability is high. In addition, when the reliability is evaluated based on the amount of received light of the distance sensor 31, the reliability can be evaluated as in the case of the optical movement measuring sensor 30.

[0307] When the reliability is evaluated based on the recognition rate and contrast distribution of the speckle pattern of the optical movement measuring sensor 30, the reliability can be evaluated based on the reliability of the measured value and the presence or absence of the influence of interference. For example, when the influence of interference light is large and the recognition rate of the speckle pattern is low, it is evaluated that the reliability is low. In this case, when the recognition rate of the speckle pattern is lower than a predetermined value, the abnormality processing unit 40i determines that the reliability does not meet the predetermined standard and performs abnormality processing.

[0308] When reliability is evaluated based on the distance the workpiece W travels between the on and off of the drawing start timing signal, shutter peeling of a corrugated cardboard as the workpiece W can be dealt with, and when the distance is a predetermined value or more, reliability is evaluated to be low.

[0309] When the reliability is evaluated based on the difference from the input of the encoder 7 , slippage or seizure of the workpiece W can be detected, and in the case where the difference is a predetermined value or more, it is evaluated that the reliability is low.

[0310] Examples of the exception processing performed by the exception processing unit 40i may include a notification process for notifying a user of an exception, an interrupt process for interrupting drawing, and a reset process for resetting a drawing start trigger. The exception processing unit 40i may perform only one of the notification process and the interrupt process, or may perform both the notification process and the interrupt process. When both the notification process and the interrupt process are performed, the notification process and the interrupt process may be performed simultaneously, or one may be performed first and then the other may be performed.

[0311] The notification process includes both a warning in which notification is performed at a stage where an abnormality may occur and a notification in which notification is performed at a stage where an abnormality occurs, and only one or both of these may be performed as the notification process.

[0312] In addition, a log of the drawing process may be stored as the exception processing performed by the exception processing unit 40i. The log to be stored includes drawing time, drawing content, drawing result, measurement result of the optical movement measuring sensor 30, etc. For example, the log may be stored in the storage unit 42.

[0313] If it is determined that the reliability evaluated by the evaluation unit 40h does not satisfy the predetermined standard in the case where drawing is performed based on the optical movement measurement sensor 30, the abnormality processing unit 40i can perform a switching process to switch to drawing based on the output of the encoder 7 as an abnormality process. In addition, in the case where drawing is performed based on the optical movement measurement sensor 30, if it is determined that the reliability evaluated by the evaluation unit 40h does not satisfy the predetermined standard, the abnormality processing unit 40i can perform a switching process to switch to constant speed drawing as an abnormality process. That is, if the reliability evaluated by the evaluation unit 40h does not satisfy the predetermined standard, the drawing control unit 40c controls the ejection of ink from the ejection port 24a based on the movement amount and drawing data acquired by the encoder 7.

[0314] Furthermore, when drawing is performed without performing the jounce correction, if the movement amount of the workpiece W in the direction perpendicular to the conveying direction is equal to or larger than a predetermined value, the abnormality processing unit 40i may perform the jounce correction as abnormality processing.

[0315] In this embodiment, the user can set the exception handling. The exception handling unit 40i generates the following Fig.35 The exception processing setting screen 200 shown is displayed on the plotter side display unit 43a or the terminal side display unit 5a. The user can set exception processing by operating the plotter side operation unit 43b or the terminal side operation unit 5b while viewing the exception processing setting screen 200.

[0316] The exception handling setting screen 200 includes: a first selection area 201, used to select whether to interrupt drawing when a warning is issued; a second selection area 202, used to select whether to interrupt drawing when an exception occurs; a third selection area 203, used to select whether to store logs when a warning is issued; a fourth selection area 204, used to select whether to perform switching processing when an exception occurs; a fifth selection area 205, used to select whether to perform switching processing when a warning is issued; and a sixth selection area 206, used to select whether to store the time when the exception occurs.

[0317] If the user operates the first selection area 201 to turn on, the drawing can be interrupted when the warning is given, and if the user operates the first selection area 201 to turn off, the drawing can be continued when the warning is given. That is, the plotter side operation unit 43b or the terminal side operation unit 5b is an example of a receiving unit that receives a selection of whether to execute the interruption process. The exception processing unit 40i is configured to execute the interruption process when receiving the execution of the interruption process, and not to execute the interruption process when receiving the non-execution of the interruption process.

[0318] If the user operates the second selection area 202 to be turned on, the drawing can be interrupted at the stage where an abnormality occurs, and if the user operates the second selection area 202 to be turned off, the drawing can be continued even if an abnormality occurs. In addition, if the user operates the third selection area 203 to be turned on, the log can be stored at the time of the warning, and if the user operates the third selection area 203 to be turned off, the log can not be stored at the time of the warning. In addition, if the user operates the fourth selection area 204 to be turned on, the switching process can be performed at the stage where an abnormality occurs, and if the user operates the fourth selection area 204 to be turned off, the switching process is not performed even if an abnormality occurs. In addition, if the user operates the fifth selection area 205 to be turned on, the switching process can be performed at the time of the warning, and if the user operates the fifth selection area 205 to be turned off, the switching process can not be performed at the time of the warning. In addition, if the user operates the sixth selection area 206 to be turned on, the time when the abnormality occurs can be stored, and if the user operates the sixth selection area 206 to be turned off, the time when the abnormality occurs is not stored.

[0319] In this way, when multiple exception processes can be executed, the user can perform an operation of selecting execution or non-execution for each exception process, and this selection operation can be received by the plotter side operation unit 43b or the terminal side operation unit 5b. Note that the number of exception processes that can be executed may be one.

[0320] Fig.36The first warning screen 210 displayed on the plotter-side display unit 43a or the terminal-side display unit 5a by executing the notification process is shown. The first warning screen 210 displays the cause of the reduced reliability and also displays a method for eliminating the cause. In this example, the cause of the reduction in the amount of received light of the optical movement measuring sensor 30 and the method for solving the reduction in the amount of received light are displayed. By executing the notification process, the abnormality processing unit 40i displays the first warning screen 210 as superimposed on the already displayed screen and displayed at the front. Therefore, the visibility of the user is improved.

[0321] Fig.37 The second warning screen 211 displayed on the plotter-side display unit 43a or the terminal-side display unit 5a by executing the notification process is shown. The second warning screen 211 displays the cause of the reduced reliability, the time when the cause occurred, and a preview of the plotting result. In this example, as the cause of the reduced reliability, the abnormality of the conveying speed of the workpiece W is displayed.

[0322] Fig.38 is a flowchart showing a series of actions for exception handling. Steps SK1 and SK2 are respectively Fig. 9 Steps SB1 and SB2 are shown to be identical. In step SK3, a draw start trigger is input. In step SK4, the draw start trigger input in step SK3 is evaluated, and processing proceeds to step SK5 if there is no problem, or returns to step SK2 if there is a problem.

[0323] In step SK5, the drawing process is started. In step SK6, the movement of the workpiece W is measured by the optical movement measuring sensor 30. In step SK7, the evaluation unit 40h evaluates the reliability of the measurement value generated by the optical movement measuring sensor 30 in step SK6. When the reliability evaluated by the evaluation unit 40h satisfies the predetermined standard, the process proceeds to step SK8, and the drawing control unit 40c controls the ejection of ink from the ejection port 24a to perform the drawing process. On the other hand, when the reliability evaluated by the evaluation unit 40h does not satisfy the predetermined standard, the process proceeds to step SK9, and the exception processing unit 40i performs exception processing. Step SK10 and Fig. 9 When the entire drawing has been completed, the process proceeds to step SK11 and waits for input of the next drawing start trigger.

[0324] Fig.39is a flowchart showing an example of exception processing in the case of performing distance measurement. In step SL1, the distance to the workpiece W in the ejection direction of the print head 24 is measured by the distance sensor 31. In step SL2, the workpiece W conveyed by the conveyor 10 is detected. In step SL3, the distance to the workpiece W in the ejection direction of the print head 24 is measured by the distance sensor 31, and the evaluation unit 40h acquires the measurement value. In step SL4, it is determined whether the measurement value acquired in step SL3 is within the distance that can be drawn. When the workpiece W is within the distance that can be drawn, the processing proceeds to step SL5. When the workpiece W is farther than the distance that can be drawn, the processing proceeds to step SL6, and the exception processing unit 40i performs exception processing.

[0325] In step SL5, it is determined whether the workpiece W has not abnormally approached or moved away from the print head 24 based on the measurement value obtained in step SL3. When the workpiece W has abnormally approached or moved away from the print head 24, it is considered that some abnormality has occurred, so the process proceeds to step SL6, and the abnormality processing unit 40i performs abnormal processing. When there is no abnormal approach or separation, the process proceeds to step SL7. In step SL7, it is determined whether the entire drawing has been completed, and if not, the process proceeds to step SL3, or if completed, the process proceeds to step SL1, and the arrival of the next workpiece W is awaited.

[0326] Fig.40 is a flowchart showing an example of a process for evaluating the reliability of a sensor value. Steps SM1 and SM2 are respectively Fig.38 In step SM3, the measurement of the optical movement measuring sensor 30 is started. In step SM4, it is determined whether the workpiece W exists within the measurable range of the optical movement measuring sensor 30. If the workpiece W does not exist, the process proceeds to step SM3, or if the workpiece W exists, the process proceeds to step SM5.

[0327] In step SM5, it is determined whether the amount of received light of the optical movement measuring sensor 30 is sufficient. If it is determined in step SM5 that the amount of received light of the optical movement measuring sensor 30 is sufficient, the process proceeds to step SM6, or if it is determined that the amount of received light of the optical movement measuring sensor 30 is insufficient, the process proceeds to step SM7.

[0328] In step SM6, it is determined whether the amount of the speckle pattern generated by the optical movement measuring sensor 30 is sufficient. When it is determined in step SM6 that the amount of the speckle pattern generated by the optical movement measuring sensor 30 is sufficient, the process proceeds to step SM8, or when it is determined that the amount of the speckle pattern generated by the optical movement measuring sensor 30 is insufficient, the process proceeds to step SM9.

[0329] In step SM8, the drawing control unit 40c performs drawing control based on the measurement value of the optical movement measuring sensor 30. Thereafter, the process proceeds to step SM10, and it is determined whether the moving distance of the workpiece W in the conveying direction is sufficient. If the moving distance of the workpiece W in the conveying direction is not sufficient, the process proceeds to step SM3, or if it is sufficient, the process proceeds to step SM1.

[0330] In step SM9 reached after it is determined in step SM6 that the amount of the speckle pattern is insufficient, the abnormality processing unit 40i notifies the user that the workpiece W cannot be measured due to scratches or disturbance light.

[0331] On the other hand, in step SM7, it is determined whether the amount of the speckle pattern generated by the optical movement measuring sensor 30 is sufficient. When it is determined in step SM7 that the amount of the speckle pattern generated by the optical movement measuring sensor 30 is sufficient, the process proceeds to step SM11, or when it is determined that the amount of the speckle pattern generated by the optical movement measuring sensor 30 is insufficient, the process proceeds to step SM12.

[0332] In step SM11, the abnormality processing unit 40i notifies the user that disturbance noise has occurred. In addition, in step SM12, the abnormality processing unit 40i notifies the user that there is no measurement target, the working distance (WD) is different, there is a hole, etc.

[0333] After steps SM9, SM11, and SM12, the process proceeds to step SM13, and the abnormality processing unit 40i switches to any one of the drawing based on the output of the encoder 7, the drawing based on the conveying speed of the immediately preceding workpiece W, and the drawing based on the preset setting value. In step SM14, the abnormality processing unit 40i performs error output or warning output to notify the user. Thereafter, the process proceeds to step SM10.

[0334] Fig.41 is a flowchart showing an example of control including drawing interrupt processing. Steps SN1 to SN4 are respectively Fig.38 SK1 to SK4 in . In step SN5, the measurement of the optical movement measuring sensor 30 is started. In step SN6, the movement of the workpiece W is measured by the optical movement measuring sensor 30. In step SN7, it is determined whether the measurement value generated by the optical movement measuring sensor 30 has a problem due to insufficient amount of received light of the optical movement measuring sensor 30 or insufficient amount of speckle pattern. When there is no problem with the measurement value generated by the optical movement measuring sensor 30, the process proceeds to step SN8, and the drawing control unit 40c performs drawing control based on the measurement value of the optical movement measuring sensor 30.

[0335] In the case where there is a problem with the measurement value generated by the optical movement measuring sensor 30, the process proceeds to step SN9, and it is determined whether the execution of the drawing interruption process has been selected. If the execution of the drawing interruption process has not been selected, the process proceeds to step SN10, or if the execution of the drawing interruption process has been selected and the drawing process is interrupted, the process proceeds to step SN12.

[0336] In step SN10, it is determined whether the execution of the switching process to switch to drawing based on the output of the encoder 7 or based on the selected preset setting value is selected. If the execution of the switching process is not selected, the process proceeds to step SN8, or if the execution of the switching process is selected, the process proceeds to step SN11, and the abnormal processing unit 40i switches the drawing to drawing based on the output of the encoder 7.

[0337] In step SN13, it is determined whether the drawing is completed, and if the drawing is not completed, the process proceeds to step SN14 to evaluate the reliability of the measured value. If the reliability of the measured value does not meet the standard, the process proceeds to step SN15 to warn the user. In step SN16, it is determined whether a setting for interrupting the drawing at the time of warning has been made, and if a setting for interrupting the drawing has been made, the process proceeds to step SN17 to interrupt the drawing and output an error. When an abnormality is detected, printing can be finally performed based on the amount of movement that meets the predetermined standard.

[0338] (Control based on the distance between the print head and the workpiece)

[0339] The drawing accuracy of the plotter 2 is determined by whether the distance (also called Throw Distance (TD), Paper Gap (PG), etc.) between the print head 24 and the workpiece W meets a predetermined standard. That is, when the distance between the print head 24 and the workpiece W is large and does not meet the predetermined standard, the landing position of the particle ink on the workpiece W deviates from the ideal position defined by the drawing data, so that the drawing disturbance increases.

[0340] When the drawing disturbance exceeds the allowable value in the drawing quality, drawing failure occurs during manufacturing and a product defect occurs. For example, in the case of drawing characters, the drawing is disturbed to the extent that it cannot be recognized visually or by OCR inspection of a print inspection machine in a subsequent process, and in the case of drawing a barcode or a two-dimensional code, the drawing is disturbed to the extent that it is impossible to read by a code reader or to the extent that a specified level of the code quality standard cannot be met.

[0341] In the inkjet printer 1 of the present embodiment, the cause of the drawing disturbance can be inferred by directly measuring the distance between the print head 24 and the workpiece W. That is, it is configured so that the distance sensor 31 of the sensor unit 3 measures the distance (TD) to the workpiece W in the ejection direction of the print head 24, and the drawing control unit 40c controls the ink ejection based on the determination result as to whether the distance to the workpiece W in the ejection direction of the print head 24 measured by the distance sensor 31 satisfies a predetermined standard. In the ink ejection control, the drawing control unit 40c acquires a timing signal generated based on a change in the distance to the workpiece W in the ejection direction of the print head 24 measured by the distance sensor 31.

[0342] For example, Fig.42 is a flowchart of control for executing drawing interrupt processing based on the result of distance measurement performed by the distance sensor 31. Steps SP1 to SP3 are respectively Fig. 9 The same as steps SB1 to SB3 in step SP4. In step SP5, it is determined whether the measurement value generated in step SP4 is abnormal. In the case where the distance to the workpiece W in the ejection direction of the print head 24 measured by the distance sensor 31 does not meet the predetermined standard, it is determined to be abnormal. Here, the predetermined standard is the distance at which the particle ink ejected from the ejection port 24a can fall on the ideal position on the workpiece W. The ideal position has a range, and when the distance to the workpiece W in the ejection direction of the print head 24 meets the predetermined standard, recognition by OCR inspection of the print inspection machine in the subsequent process is possible, and in the case of drawing a barcode or a two-dimensional code, reading by a code reader is possible. On the other hand, when drawing is performed in the case where the distance to the workpiece W in the ejection direction of the print head 24 does not meet the predetermined standard, there is a possibility that it cannot be recognized by the OCR inspection, and the barcode or two-dimensional code cannot be read by the code reader.

[0343] When it is determined in step SP5 that the distance is the normal distance, the process proceeds to step SP6, and the workpiece movement amount acquisition unit 40d acquires the movement amount of the workpiece W based on the measurement value output from the optical movement measuring sensor 30. Steps SP7 to SP9 are respectively Fig. 9 Steps SB5 to SB7 are the same as in .

[0344] When it is determined in step SP5 that the distance is an abnormal distance, since the distance to the workpiece W in the ejection direction of the print head 24 measured by the distance sensor 31 does not satisfy the predetermined standard in this case, the drawing interruption process is performed without performing the drawing process, and the flow ends. Note that the timing for performing the drawing interruption process may be any timing from the start of drawing to immediately before the end. In particular, when the drawing interruption process is performed before starting drawing, a loss caused by a failure in drawing the workpiece W can be avoided.

[0345] Fig.43 is a flowchart showing an example of control for notifying a distance abnormality based on the result of distance measurement. Steps SQ1 to SQ9 are respectively Fig.42 The steps SP1 to SP9 shown in the figure are the same. In the case where it is determined in step SQ5 that the distance is an abnormal distance, the process proceeds to step SQ10, and for example, the abnormality processing unit 40i performs a distance abnormality notification. The distance abnormality notification is a process of notifying the user that the distance to the workpiece W in the ejection direction of the print head 24 measured by the distance sensor 31 is abnormal. The abnormality processing unit 40i generates a screen for notification and displays the screen on the plotter side display unit 43a or the terminal side display unit 5a. Fig.43 In the example shown, a distance abnormality notification is performed, and a drawing interruption process is performed. For example, when the distance to the workpiece W in the ejection direction of the print head 24 measured by the distance sensor 31 is the same as the distance that can be drawn, drawing is continued after the distance abnormality is notified, and the drawing quality is judged visually or by an inspection machine in a subsequent process.

[0346] Fig.44 is a flowchart showing an example of control for notifying a distance abnormality based on the result of distance measurement and continuing drawing. Steps SR1 to SR9 are respectively Fig.43 In step SR10, the same as steps SQ1 to SQ9 shown in FIG. Fig.43 The illustrated step SQ10 similarly performs distance abnormality notification, and then the process proceeds to step SR6 to continue drawing.

[0347] For example, when the distance to the workpiece W in the ejection direction of the print head 24 measured by the distance sensor 31 is the same as the distance that can be drawn, drawing is interrupted after notifying the distance abnormality, and the user is caused to perform processing in the case of drawing abnormality. For example, the workpiece W of which the distance abnormality has been notified is excluded by the exclusion device in the subsequent process, or is manually excluded by the operator after the conveyor 10 stops.

[0348] Fig.43The distance abnormality notification shown can be performed with different notification names between the case where the distance is determined to be abnormal before the drawing start position and the case where the distance is determined to be abnormal after the drawing start position. When the distance is determined to be abnormal before the drawing start position, the user can be notified that there is no defective drawing on the workpiece W and the workpiece W can be reused. On the other hand, when the distance is determined to be abnormal after the drawing start position, the user can be notified that there is a possibility of drawing failure in the workpiece W. Therefore, different processing can be performed in the subsequent stage.

[0349] In addition, the distance used as a threshold for determining whether the distance is abnormal may be a fixed value of the device at the time of factory shipment, or may be a value that can be set by the user in consideration of the dependence on the user's installation environment. In addition, the distance used as a threshold for determining whether the distance is abnormal is not necessarily a single value, and multiple distance thresholds may be used to determine the abnormality and distinguish between the case where the drawing will be interrupted and the case where the drawing continues. That is, the distance threshold for interrupting the drawing and the distance threshold for continuing may be used to determine the abnormality. In addition, the user may be allowed to set whether to continue or interrupt the drawing after the distance is determined to be abnormal. In addition, when the distance is determined to be abnormal, some notifications may be given to the user to optimize the working distance.

[0350] Fig.45 is a flowchart showing an example of control in which a drawing start trigger is disabled in the case of a distance abnormality and then a drawing start trigger input is enabled. Steps SU1 to SU6 are respectively Fig.44 . In the case where the distance to the workpiece W in the ejection direction of the print head 24 measured by the distance sensor 31 is an abnormal distance, the process proceeds to step SU7, and it is determined whether it is before the start of drawing. If it is before the start of drawing, the process proceeds to step SU8, and the drawing start process is canceled, that is, the drawing start trigger is invalidated. If it is after the start of drawing, the process proceeds to step SU6. Steps SU9 to SU11 are respectively the same as Fig.44 Steps SR7 to SR9 are the same as in FIG.

[0351] For example, in the case where the workpiece W is a corrugated cardboard, in a line where a defect of the shutter of the corrugated cardboard being half-opened frequently occurs due to a box production failure or the like, the drawing start point in the timing sensor 8 may be incorrect, or the movement amount measurement may not be correctly performed due to a deviation from the measurable distance or a decrease in measurement accuracy when the optical movement measurement sensor 30 is used. In this case, the drawing start trigger is temporarily invalidated, and then a point at which the distance measurement is stable is used as a trigger, so that drawing can be performed on the workpiece W based on the correct end surface.

[0352] (Event detection and log file storage processing)

[0353] At the point where the workpiece W is conveyed, a change in the conveying speed of the conveyor 10 and a change in the position of the workpiece W in the width direction on the conveying surface 10a occur, and in principle, an error also occurs due to the sliding of the workpiece W on the conveying surface 10a. If the above-mentioned change or error exceeds the preset landing accuracy tolerance of the particle ink, a drawing failure results.

[0354] Drawing failure includes various events such as missing or omitted characters, segmentation and contamination of characters, etc. When drawing failure occurs on the conveyor 10, it is necessary to collect information such as drawing execution time and drawing interval, identify the cause of the drawing failure, and perform countermeasures, but it may be difficult to identify the cause.

[0355] Fig.46 1 is a timing diagram of the input of the drawing start trigger output from the timing sensor 8 and the execution of the drawing. As shown in the figure, the drawing machine 2 performs drawing according to the conveying speed of the workpiece W when the workpiece W passes in front of it. In the case of such a drawing system, conventionally, only the drawing time and the drawing interval are information that can be left when the drawing is performed. It is extremely difficult to estimate the cause of the above-mentioned drawing failure based only on the information about the drawing time and the drawing interval.

[0356] The inkjet printer 1 of the present embodiment has a recorder function that makes it possible to easily analyze the cause of a specific event (e.g., a drawing failure) that occurs during operation after the fact. This makes it possible to solve conventional problems associated with identifying the cause of a drawing failure.

[0357] like Figure 2 As shown, the inkjet printer 1 includes an event detection unit 45 and a storage processing unit 46 as a part realizing a recorder function. The event detection unit 45 is a part that detects an event related to a drawing state based on the distance sensor 31 and the optical movement measuring sensor 30 of the sensor unit 3. The storage processing unit 46 is a part that stores information about the measurement values ​​generated by the optical movement measuring sensor 30 and the distance sensor 31 and information about the event in association with at least a part of the drawing data in the storage unit 42 or the like as a log file in response to the detection of the event by the event detection unit 45. For example, the conveying speed of the workpiece W generated by the optical movement measuring sensor 30, the movement amount of the workpiece W in a direction perpendicular to the conveying direction, the moving speed of the workpiece W in a direction perpendicular to the conveying direction, and the like can be stored as a log file. In addition, the distance between the print head 24 and the workpiece W generated by the distance sensor 31 can also be stored as a log file. In addition, various types of information such as the temperature of the print head 24 and the remaining amount of ink, for example, can be stored as a log file. The storage destination of the log file is not limited to the storage unit 42, and may be another storage device or the like.

[0358] Fig.47 is a flowchart showing the log file storage process during the drawing period. In step SV1, the drawing machine 2 waits for drawing to start, waits for a predetermined time, and then proceeds to step SV2. In step SV2, a timing signal is input, and the process proceeds to step SV3. If no timing signal is input, the process remains in step SV1.

[0359] In step SV3, the drawing process is performed, the distance sensor 31 measures the distance between the print head 24 and the workpiece W to generate a measurement value, and the optical movement measuring sensor 30 measures the movement amount of the workpiece W to generate a measurement value. If the process proceeds to step SV4 and the drawing process is completed, the process proceeds to step SV5, and the measurement values ​​during the drawing period are stored in the storage unit 42 as a log file.

[0360] The event detection unit 45 detects that the measurement value measured by the distance sensor 31 exceeds a predetermined range as an event related to the drawing state. That is, since it can be estimated that the workpiece W has collided with the print head 24 when the distance between the print head 24 and the workpiece W is negative, this is detected by the event detection unit 45 as an event related to the drawing state.

[0361] When the distance between the print head 24 and the workpiece W exceeds the drawing distance range of the plotter 2 and the print head 24 and the workpiece W are far away from each other, it is assumed that the measurement value measured by the distance sensor 31 is outside the predetermined range. Since drawing is disturbed if the distance between the print head 24 and the workpiece W exceeds the drawing distance range of the plotter 2, this is detected by the event detection unit 45 as an event related to the drawing state.

[0362] When the distance between the print head 24 and the workpiece W varies greatly during drawing, it can be estimated that, for example, the workpiece W is bent off the guide of the conveyor 10. Since drawing is disturbed in this case, this is detected by the event detection unit 45 as an event related to the drawing state.

[0363] The event detection unit 45 detects that the measurement value generated by the optical movement measurement sensor 30 exceeds a predetermined range as an event related to the drawing state. The predetermined range is a range in which favorable drawing quality can be maintained. When the conveying speed of the workpiece W generated by the optical movement measurement sensor 30 is not constant, it can be estimated that, for example, the workpiece W is blocked when contacting with a guide or the like of the conveyor 10. Since the drawing is disturbed in the case where the conveying speed of the workpiece W is not constant, this is detected by the event detection unit 45 as an event related to the drawing state.

[0364] In the case where there is a period in which the conveying speed of the workpiece W generated by the optical movement measuring sensor 30 is zero, it can be estimated that, for example, the conveyor 10 suddenly stops, etc. Since the situation in which there is a period in which the conveying speed of the workpiece W is zero is not a normal state and causes interference with drawing, this is detected by the event detection unit 45 as an event related to the drawing state.

[0365] When the movement of the workpiece W in the direction perpendicular to the conveying direction is intermittently measured by the optical movement measuring sensor 30, it can be estimated that the workpiece W is bumping. Since drawing is disturbed unless the bump correction process is performed when the workpiece W is bumping, this is detected by the event detection unit 45 as an event related to the drawing state.

[0366] The event detection unit 45 detects that the measurement value related to the movement of the workpiece W in the direction perpendicular to the conveying direction measured by the optical movement measuring sensor 30 exceeds a predetermined range as an event related to the drawing state. In addition, since the optical movement measuring sensor 30 can generate measurement values ​​related to the movement of two axes orthogonal to each other, the event detection unit 45 detects that the measurement value related to the movement in the conveying direction determined based on the measurement values ​​of the two axes measured by the optical movement measuring sensor 30 exceeds a predetermined range as an event related to the drawing state.

[0367] For example, when the optical movement measuring sensor 30 measures that the workpiece W moves at a substantially constant speed in a direction perpendicular to the conveying direction, it is possible to estimate that the line of the conveyor 10 is tilted or the plotter 2 is tilted with respect to the conveying direction of the workpiece W. Since the drawing is disturbed while the workpiece W moves at a constant speed in a direction perpendicular to the conveying direction, this is detected by the event detection unit 45 as an event related to the drawing state.

[0368] Fig.48 The drawing result confirmation screen 140 is shown which allows the user to confirm the contents of the log file stored by the storage processing unit 46. Figure 2 As shown, the inkjet printer 1 includes a presentation unit 47 that presents information about the measurement values ​​generated by the optical movement measurement sensor 30 and the distance sensor 31. The presentation unit 47 generates Fig.48 The drawing result confirmation screen 140 shown is displayed on the drawing machine side display unit 43a or the terminal side display unit 5a, or data required for drawing is output and displayed on an external device.

[0369] The drawing result confirmation screen 140 is provided with: a number display area 141 in which a number (drawing number) is displayed as an example of information for identifying a drawing process; a distance display area 142 in which the distance between the print head 24 and the workpiece W is displayed; a speed display area 143 in which the conveying speed of the workpiece W is displayed; and a vertical direction display area 144 in which the movement amount of the workpiece W in the direction perpendicular to the conveying direction and the movement speed of the workpiece W in the direction perpendicular to the conveying direction are displayed. The drawing number, distance, speed, and movement amount are displayed side by side in the horizontal direction so that the distance, speed, movement amount, etc. in the drawing process identified by the drawing number are associated with the drawing number. The array direction of these items may be the vertical direction. In addition, any one or two of the distance, speed, and movement amount may be displayed.

[0370] Each of the distance, speed, and movement amount is compared with a predetermined range (also referred to as a threshold value), and the numerical value exceeding the predetermined range is displayed in a manner that can be distinguished from other numerical values. For example, by highlighting, bolding, or changing the color of the numerical value exceeding the predetermined range, the numerical value exceeding the predetermined range can be easily understood. In this way, the storage processing unit 46 can store the comparison result between the measurement value generated by the distance sensor 31 and the threshold value. The presentation unit 47 can present the comparison result between the measurement value generated by the distance sensor 31 and the threshold value to the user in various ways.

[0371] In addition, a real-time clock may be built into the plotter 2 or the controller 4. When the real-time clock is built into the plotter 2 or the controller 4, the storage processing unit 46 may store the plotting number and the time in association with each other. This makes it possible to associate the time at which an event occurred with the log. In addition, it is also possible to selectively display only the log file for which an event has occurred.

[0372] Since the storage processing unit 46 collects log files, the presentation unit 47 can generate statistical information and present the generated statistical information to the user through the plotter-side display unit 43a or the terminal-side display unit 5a.

[0373] Here, generally, there is a concept of a job in the drawing machine 2 for industrial use. For example, there is a job for each type of workpiece W, and in this case, the job is a job in which drawing data is set for each type.

[0374] When the presentation unit 47 generates statistical information, the log files collected by the storage processing unit 46 are read and sorted based on a predetermined period. Examples of predetermined periods include "day", "shift", "week" and "job". For example, only log files of a specific job can form a set.

[0375] The statistical information includes: the maximum value, minimum value, and average value of the distance between the print head 24 and the workpiece W during a predetermined period, the maximum value, minimum value, and average value of the conveying speed of the workpiece W, the maximum value, minimum value, and average value of the movement amount of the workpiece W in the direction perpendicular to the conveying direction, the number of times the distance between the print head 24 and the workpiece W exceeds a predetermined range, the number of times the conveying speed of the workpiece W exceeds a predetermined range, the number of times the movement amount of the workpiece W in the direction perpendicular to the conveying direction exceeds a predetermined range, etc. The presentation unit 47 displays the information in the form of Fig.48 The tabular format shown presents some or all of these statistics.

[0376] The presentation unit 47 can present not only statistical information but also time series data to the user. The time series data may include a plurality of data, such as the distance between the print head 24 and the workpiece W before and after the event is detected, the conveying speed of the workpiece W, and the amount of movement of the workpiece W in a direction perpendicular to the conveying direction. In this case, the storage processing unit 46 stores the distance between the print head 24 and the workpiece W before and after the event is detected, the conveying speed of the workpiece W, and the amount of movement of the workpiece W in a direction perpendicular to the conveying direction in association with at least a portion of the drawing data. The storage processing unit 46 can set any storage period for the time series data, and, for example, the storage processing unit 46 stores information about the measured value and information about the event as time series data from the time point when the timing sensor 8 outputs the timing signal until the drawing on the workpiece W is completed.

[0377] The inkjet printer 1 includes a temporary storage unit 46a that temporarily stores information about the measurement value generated by the optical movement measuring sensor 30. The temporary storage unit 46a stores the measurement value of the optical movement measuring sensor 30 regardless of the presence or absence of an event. When the event detection unit 45 detects an event, the storage processing unit 46 reads information corresponding to the event from the information stored in the temporary storage unit 46a, and stores the read information in association with at least a portion of the drawing data.

[0378] When the presentation unit 47 presents the time series data, as shown in FIG. Fig.49 The graph display screen 150 is generated and displayed on the plotter side display unit 43a or the terminal side operation unit 5b. In the graph, the horizontal axis represents time and the vertical axis represents the distance between the print head 24 and the workpiece W.

[0379] Regardless of whether the event is detected before or after, the time series data can be displayed on the graph display screen 150 based on the log file. Fig.49As can be seen from the graph shown, the distance between the print head 24 and the workpiece W tends to increase over time, and therefore, the deviation of the track guiding the workpiece W on the production line, the position change of the plotter 2, etc. can be estimated. Therefore, countermeasures can be taken before a printing failure occurs. Note that in the case of displaying time series data before and after an event is detected, it can be assumed that the event has occurred in the central part in the time axis direction.

[0380] The controller 4 may be provided with a communication module capable of communicating with the outside. In this case, for example, at least one of the log file, statistical information, and time series data may be sent to a device desired by the user and used in the device.

[0381] In addition, the user can also extract and use the data included in the log file. After extracting the desired data from the data included in the log file, the user can edit and process the extracted data using another tool or the like to use as a production report or the like.

[0382] An example of the information about the measurement value stored in the storage processing unit 46 may include data of the amount of light received by the optical movement measuring sensor 30, and may include time series data of the amount of light received by the optical movement measuring sensor 30 before and after the event is detected. In this case, the event detection unit 45 detects the event based on a decrease in the amount of light received by the optical movement measuring sensor 30. That is, when ink droplets splashed from the workpiece W adhere to the window 32b of the sensor housing 32, the amount of light received by the optical movement measuring sensor 30 may decrease, resulting in a state where the measurement accuracy is reduced or measurement cannot be performed. This is an event that causes interference with drawing, and is therefore detected by the event detection unit 45 as an event related to the drawing state.

[0383] The inkjet printer 1 includes a cleaning unit 49 (in Figure 2 ), when the event detection unit 45 detects an event based on a decrease in the amount of light received by the optical movement measuring sensor 30, the cleaning unit 49 cleans the window 32b of the sensor housing 32. The cleaning unit 49 includes a device such as a blower (an example of a positive pressure generator) that blows compressed air to the window 32b and a wiper that wipes the window 32b, and is a part that automatically cleans the window 32b. Note that the user may be prompted to clean the window 32b so that the user performs the cleaning.

[0384] (Inspection device)

[0385] Fig.50An example of using the inspection device 500 during the operation of the plotter 2 is shown. The inspection device 500 is a device configured to inspect information drawn by the plotter 2 on the workpiece W conveyed by the conveyor 10. The installation position of the inspection device 500 is located downstream of the plotter 2 in the conveying direction of the workpiece W. At the installation position, the inspection device 500 captures an image of the information drawn on the workpiece W to generate an inspection image, and determines "pass" or "fail" of the drawing state based on the generated inspection image. That is, the inspection device 500 is an image inspection machine. The inspection device 500 may constitute a part of the inkjet printer 1, or may be a device separate from the inkjet printer 1.

[0386] like Fig.51 As shown, the inspection device 500 includes a main body 510, a sensor unit 3, a controller 4, and an operation terminal 5. The sensor unit 3, the controller 4, and the operation terminal 5 are the same as those described above. The main body 510 can be incorporated in the sensor unit 3. The external device 6, the power supply 100, the encoder 7, and the timing sensor 8 are also the same as those described above. The external device 6, the power supply 100, the encoder 7, and the timing sensor 8 can be devices that each constitute a part of the inspection device 500, or can be devices separated from the inspection device 500. In addition, the inkjet printer 1 can include the inspection device 500 and the plotter 2, or can be configured without the inspection device 500.

[0387] The main body 510 includes an imaging unit 511, an illumination unit 512, a storage unit 513, and an arithmetic processing unit 514. The imaging unit 511, the illumination unit 512, the storage unit 513, and the arithmetic processing unit 514 may be integrated, or only a part thereof may be detachable.

[0388] The lighting unit 512 is a part that illuminates the inspection target area, and includes a light emitting element configured using, for example, an LED. The imaging unit 511 is a part that captures an image of the inspection target area to generate an inspection image, and includes an optical system 511a and an imaging substrate 511b. The optical system 511a includes a lens that receives light emitted from the lighting unit 512 and reflected by the inspection target area. The inspection target area in the inspection device 500 is a drawing area on the workpiece W.

[0389] The imaging substrate 511b includes a complementary MOS (CMOS) image sensor 511c, an FPGA 511d, and a DSP 511e. The image sensor 511c is a part that receives light incident from the optical system and generates an inspection image. The FPGA 511d and the DSP 511e are configured to perform filtering processing on the inspection image inside the imaging unit 511, and the signal output from the CMOS sensor 511c is input to the FPGA 511d and the DSP 511e.

[0390] In addition, the storage unit 513 stores an inspection parameter for determining "pass" or "failure" of a drawing state related to information drawn on the workpiece W. For example, a plurality of types of inspection parameters may be pre-stored in the storage unit 513, and the plurality of types of inspection parameters may include a first inspection parameter for determining "pass" or "failure" of a drawing state related to information drawn on the workpiece W and a second inspection parameter for determining "pass" having a smaller tolerance than the first inspection parameter. The storage unit 513 may be configured using a portion of the storage unit 42 of the controller 4 of the inkjet printer 1.

[0391] The arithmetic processing unit 514 includes a pass / fail judgment unit 514a and a determination unit 514b. The pass / fail judgment unit 514a is a part that judges "pass" or "fail" of the drawing state related to the information drawn on the workpiece W based on the inspection image generated by the imaging unit 511 and the inspection parameters stored in the storage unit 513. The pass / fail judgment unit 514a and the determination unit 514b can be provided inside the drawing machine 2 or inside the operation terminal 5. In addition, the determination unit 514b can be provided in the controller 4.

[0392] The inspection device 500 can switch between a setting mode and an operation mode. In the setting mode, various parameter settings are performed, such as imaging settings, registration of a main image used as a standard for pass / fail determination, generation (learning) of a discriminator that enables internal discrimination between a non-defective product image and a defective product image. In the operation mode, a pass / fail determination of a drawing state is performed based on an inspection image obtained by capturing an image of an inspection target area at a location where a drawing process is actually performed. In the setting mode, a user performs a preliminary operation to enable separation of non-defective products and defective products by an intended inspection.

[0393] The inspection device 500 is capable of switching between a rule-based inspection mode (standard inspection mode) and a learning-based inspection mode (learning inspection mode). In the rule-based inspection mode, a pass / fail judgment of a drawing state is performed based on various characteristic quantities (e.g., color, edge, position, etc.) in an inspection image. In the learning-based inspection mode, a discriminator is generated and a pass / fail judgment of a drawing state is performed by the generated discriminator. In the standard inspection mode, a user sets which characteristic quantity included in an image is used to perform inspection and a threshold value (a part of an inspection parameter), and a pass / fail judgment is performed according to the setting.

[0394] In the case where important characters such as the production date and time or the consumption expiration date as a product have been drawn, the inspection device 500 determines whether the character string preset by the user in the drawing general setting has been obtained based on the image recognition result in the pass / fail judgment of the drawing state. Fig. 8A Step SA2 in). Various methods can be considered as pass / fail judgment based on image recognition results. For example, check whether there are blobs (clusters of black pixels) that look like characters in the image, and if there are blobs, check whether there are a predetermined number of blobs in the image, etc. In addition, when performing the pass / fail judgment of the drawing state, the judgment can be performed based on whether the reading through OCR recognition is possible. Generally, the pass / fail judgment using OCR recognition can obtain a result with higher accuracy, but it is inevitable that the erroneous reading of the character string (the drawing result expected to be judged as normal is judged as abnormal) occurs with a certain probability as the OCR result of the inspection device 500. The reason for the misjudgment in the case of using OCR recognition is that the non-defective product standard that a person can visually read does not match the non-defective product standard judgment in the OCR recognition of the inspection device 500. Products that are judged not to be non-defective products are excluded from the production line and are regarded as defective products, and therefore, it is necessary to confirm and discard the misjudged non-defective products by visual inspection again, and there is a problem of reduced production efficiency.

[0395] For example, as described above, in the case where the user cannot allow the above-mentioned discarding, the check as to whether the character string preset by the user in the drawing general setting has been obtained is adopted as described above, but the check is only a check as to whether there are characters and whether the number of characters is correct. Therefore, errors in the character string and the drawing quality cannot be determined, and defective products are allowed to flow to the subsequent process as non-defective products, which is contrary to the check using OCR recognition, and there is a disadvantage of causing additional costs because defective products released to the market need to be reworked and recovered in the subsequent process.

[0396] Therefore, in the present embodiment, when the position or movement of the workpiece W does not correspond to the inspection object, the drawing state is determined to be "failed". For example, when the position or movement of the workpiece W does not correspond to the inspection object, the drawing state can also be determined to be "failed" regardless of the inspection image generated by the imaging unit 511. Therefore, a pass / fail determination close to a visual sense can be performed. Hereinafter, a specific description will be given.

[0397] First, the determination unit 514b will be described. The determination unit 514b determines whether the position or movement of the workpiece W is not part of the object to be inspected based on the measurement value generated by the optical movement measuring sensor 30 or the measurement value generated by the distance sensor 31. When the determination unit 514b determines whether the position or movement of the workpiece W does not correspond to the inspection target, various methods can be used, and some of them will be described below.

[0398] For example, when the measurement value generated by the distance sensor 31 exceeds a predetermined range, the determination unit 514b determines that the position or movement of the workpiece W does not correspond to the inspection target. In addition, when the measurement value measured by the optical movement measuring sensor 30 is outside the predetermined range, the determination unit 514b determines that the position or movement of the workpiece W does not correspond to the inspection target. In addition, in the case where the optical movement measuring sensor 30 generates a measurement value related to the movement of the workpiece W in a direction perpendicular to the conveying direction of the conveyor 10, when the measurement value related to the movement of the workpiece W in the direction perpendicular to the conveying direction measured by the optical movement measuring sensor 30 is outside the predetermined range, the determination unit 514b determines that the position or movement of the workpiece W does not correspond to the inspection target. In addition, in the case where the optical movement measuring sensor 30 generates measurement values ​​of two axes orthogonal to each other, when the measurement value related to the movement in the conveying direction determined based on the measurement values ​​of the two axes measured by the optical movement measuring sensor 30 is outside the predetermined range, the determination unit 514b determines that the position or movement of the workpiece W does not correspond to the inspection target.

[0399] In the case where the optical movement measuring sensor 30 acquires the current offset position relative to the reference position of the workpiece W, when the current offset position acquired by the optical movement measuring sensor 30 is outside the predetermined range, the determination unit 514b determines that the position or movement of the workpiece W does not correspond to the inspection target. In addition, when the accuracy of the measurement value generated by the optical movement measuring sensor 30 is below the predetermined value, the determination unit 514b determines whether the position or movement of the workpiece W does not correspond to the inspection target based on the movement amount of the conveyor 10 with respect to the workpiece W acquired by the workpiece movement amount acquisition unit 40d of the controller 40. In addition, the determination unit 514b determines whether the measurement value generated by the optical movement measuring sensor 30 exceeds a threshold value, and determines whether the position or movement of the workpiece W does not correspond to the inspection target based on the movement amount of the conveyor 10 with respect to the workpiece W acquired by the workpiece movement amount acquisition unit 40d until the measurement value generated by the optical movement measuring sensor 30 exceeds the threshold value, and when the measurement value generated by the optical movement measuring sensor 30 exceeds the threshold value, determines whether the position or movement of the workpiece W does not correspond to the inspection target based on the measurement value generated by the optical movement measuring sensor 30.

[0400] When the determination unit 514b determines that the position or movement of the workpiece W does not correspond to the inspection target, the pass / fail determination unit 514a determines that the drawing state is "failed" regardless of the inspection image generated by the imaging unit 511. By adding the measurement value related to the position or movement of the workpiece W to the pass / fail determination in the pass / fail determination unit 514b, a pass / fail determination close to the visual sense becomes possible. On the other hand, when the determination unit 514b determines that the position or movement of the workpiece W corresponds to the inspection target, the pass / fail determination unit 514a performs a pass / fail determination based on the inspection image generated by the imaging unit 511.

[0401] In the case where the first inspection parameter and the second inspection parameter are stored in the storage unit 513, when the pass / fail determination unit 514a performs the pass / fail determination, the “pass” or “fail” of the drawing state is determined based on the first inspection parameter and the inspection image generated by the imaging unit 511. However, when the determination unit 514b determines that the position or movement of the workpiece W does not correspond to the inspection target, the pass / fail determination unit 514a determines the “pass” or “fail” of the drawing state based on the second inspection parameter and the inspection image generated by the imaging unit 511.

[0402] When the inspection device 500 is used, the pass / fail determination result, inspection image, etc. of the inspection device 500 can be output to the controller 4 by connecting the inspection device 500 and the controller 4 of the inkjet printer 1 so as to be communicable. In this case, Figure 2 The event detection unit 45 shown can detect an event related to the drawing state based on the determination result of the inspection device 500. The storage processing unit 46 stores information about the inspection image captured by the imaging unit 511 of the inspection device 500 in association with at least a part of the drawing data. Note that the inspection device 500 and the operation terminal 5 can be connected to be able to communicate so as to output the pass / fail determination result of the inspection device 500, the inspection image, etc. to the operation terminal 5.

[0403] The presentation unit 47 may present information about the measurement value generated by the optical movement measuring sensor 30 or the measurement value generated by the distance sensor 31 and information about the inspection image captured by the imaging unit 511 of the inspection device 500 in association with at least a portion of the drawing data. Fig.52As shown in FIG. 1 , as a result of the user browsing the drawing result confirmation screen 140 to confirm the log file, in the case where there is a value (abnormal value) exceeding a predetermined range among the values ​​indicating the distance, speed, and movement amount, if the user selects the drawing number to which the abnormal value belongs, the presentation unit 47 displays an image display confirmation window 160 to be superimposed on the drawing result confirmation screen 140. The image display confirmation window 160 has a display button 160a and a non-display button 160b. When the display button 160a is operated, as shown in FIG. Fig.53 As shown, the presentation unit 47 displays an image display window 161 for displaying the inspection image corresponding to the drawing number to be superimposed on the drawing result confirmation screen 140. The drawing result confirmation screen 140 may include at least one of the drawing data extracted from the inspection image, the drawing state, and the margin in the case of judging "pass".

[0404] Fig.54 1 is a flowchart showing an example of processing in the case where a pass / fail determination is performed using the measurement results of the conveying speed and distance of the workpiece W. Steps S101 to S103 are respectively Fig. 9 SB1 to SB3 shown are the same. In step S104, the determination unit 514b of the inspection device 500 performs distance measurement based on the measurement value generated by the distance sensor 31. In step S105, the determination unit 514b determines whether the distance detected in step S104 is abnormal, that is, whether the measurement value generated by the distance sensor 31 exceeds a predetermined range. When it is determined that the distance is normal (the measurement value generated by the distance sensor 31 is within the predetermined range), the process proceeds to step S106, and the determination unit 514b obtains the movement amount of the workpiece W based on the measurement value generated by the optical movement measurement sensor 30. In the case where it is determined in step S105 that the distance is abnormal (the measurement value generated by the distance sensor 31 exceeds the predetermined range), the process proceeds to step S107, and the determination unit 514b records the distance abnormality in the storage unit 513, etc., and then the process proceeds to step S106.

[0405] In step S108, the determination unit 514b determines whether the transmission speed detected in step S106 is abnormal, that is, whether the measurement value generated by the optical movement measuring sensor 30 exceeds the predetermined range. When it is determined that the transmission speed is normal (the measurement value generated by the optical movement measuring sensor 30 is within the predetermined range), the process proceeds to step S110. When it is determined in step S108 that the transmission speed is abnormal (the measurement value generated by the optical movement measuring sensor 30 is outside the predetermined range), the process proceeds to step S109, and the determination unit 514b records the abnormality of the transmission speed in the storage unit 513, etc., and then the process proceeds to step S110. Steps S110 and S111 are respectively related to Fig. 9Steps SB6 and SB7 in are the same.

[0406] In step S112, the inspection device 500 sends the distance abnormality record in step S107 and the transmission speed abnormality record in step S109 to the plotter 2. Fig.54 As shown, it can be determined as abnormal when there is at least one abnormality, or it can be determined as abnormal when the abnormality occurs continuously for more than a specified number of times. In addition, the abnormality can be determined according to an algorithm.

[0407] Note that when the number of characters to be printed on the workpiece W is set to, for example, four and the inspection device 500 has determined that the number of characters to be printed is five, if the distance and the movement amount are normal, it can be determined as a non-defective product.

[0408] Fig.55 is a flowchart showing an example of the inspection process after the drawing process is completed. In step S201, the inspection device 500 waits for the drawing inspection to start. In step S202, the inspection device 500 obtains Fig.54 The distance abnormality record and the transmission speed abnormality record recorded in the flowchart shown. In step S203, it is determined whether a trigger for starting the drawing inspection has been input. When the trigger for starting the drawing inspection is input, the processing proceeds to step S204, and the drawing inspection processing is started. In step S205, as a result of the determination performed by the pass / fail determination unit 514a based on the inspection image and the inspection parameter, the process proceeds to step S206 in the case of "failure", or proceeds to step S207 in the case of "pass". In step S207, the pass / fail determination unit 514a performs a determination on the distance abnormality, and in the case of the distance abnormality, proceeds to step S208 determined as "failure", and in the case of "pass", proceeds to step S209. In step S209, the pass / fail determination unit 514a performs a determination on the transmission speed abnormality, and in the case of the transmission speed abnormality, proceeds to step S210 determined as "failure", and in the case of "pass", proceeds to step S211.

[0409] In step S211, it is assumed that the drawing status is "passed". In step S212, the user is notified of the "pass" or "failure" of the drawing status, and when the drawing status is "failed", the user is also notified of the cause and reason. For example, the presentation unit 47 may present the reason why the inspection device 500 determines that the drawing status is "failed" in association with at least a part of the drawing data. Examples of the cause may include a distance abnormality (the workpiece W is too far from the print head 24) and a conveying speed abnormality (the conveying speed of the workpiece W is too slow, too fast, or varies).

[0410] The presentation unit 47 may also present a method for correcting the drawing state corresponding to the reason why the inspection device 500 determines that the drawing state is "failed". For example, in a case where the reason why the drawing state is determined to be "failed" is a distance abnormality, as a method for correcting the drawing state, a method for adjusting the guide so that the workpiece W does not move away from the print head 24 is presented to the user. In addition, in a case where the reason why the drawing state is determined to be "failed" is a conveying speed abnormality, as a method for correcting the drawing state, a method for adjusting the speed of the workpiece W within a prescribed speed range is presented to the user. The plotter 2 may obtain the reason why the drawing state is determined to be "failed" and automatically perform drawing state correction corresponding to the reason.

[0411] Fig.56 1 is a flowchart showing an example of processing in the case where a pass / fail determination is performed using the measurement results of the movement and distance perpendicular to the conveying direction of the workpiece W. Steps S301 to S305 and S307 are respectively Fig.54 Steps S101 to S105 in are the same as S107. In step S306, not only the movement amount (movement speed) of the workpiece W in the conveying direction but also the movement amount (movement speed) in the direction perpendicular to the conveying direction is measured.

[0412] Steps S308 and S309 are Fig.54 The same as steps S108 and S109 in . In step S310, the determination unit 514b determines whether the vibration of the workpiece W is abnormal based on the amount of movement of the workpiece W in the direction perpendicular to the conveying direction. When it is determined that the vibration of the workpiece W is abnormal, the processing proceeds to step S311, and the determination unit 514b records the abnormal vibration of the workpiece W in the storage unit 513, etc., and then the processing proceeds to step S312. In step S312, the inclination of the conveying direction of the workpiece W is calculated based on the amount of movement of the workpiece W in the conveying direction and the amount of movement of the workpiece W in the direction perpendicular to the conveying direction, and it is determined whether the calculated inclination is abnormal. When it is determined that the inclination of the conveying direction of the workpiece W is abnormal, the processing proceeds to step S313, and the determination unit 514b records the abnormal inclination of the conveying direction of the workpiece W in the storage unit 513, etc., and then the processing proceeds to step S314. Steps S314 and S315 are respectively the same as Fig.54 Steps S110 and S111 in are the same.

[0413] In step S316 , the inspection device 500 transmits the abnormal record of the conveying speed in step S309 , the abnormal record of the vibration of the workpiece W in step S311 , and the abnormal record of the tilt in the conveying direction of the workpiece W in step S313 to the plotter 2 .

[0414] Fig.574 is a flowchart showing an example of an inspection process using the measurement results of the movement and distance perpendicular to the conveying direction of the workpiece W. Steps S401 to S410 are respectively Fig.55 In step S411, the pass / fail determination unit 514a determines the vibration abnormality of the workpiece W, proceeds to step S412 for determination of "failure" in the case of vibration abnormality, and proceeds to step S413 for determination of "pass".

[0415] In step S413 , the pass / fail determination unit 514 a determines whether the tilt of the workpiece W in the conveying direction is abnormal, and proceeds to step S414 for determination of “failure” if the tilt is abnormal, and proceeds to step S415 for determination of “pass” if the tilt is abnormal.

[0416] In step S415, it is assumed that the drawing status is "passed". In step S416, the user is notified of the drawing status of "passed" or "failed", and when the drawing status is "failed", the user is also notified of the cause and reason. For example, the user may be notified that the conveying direction of the workpiece W is tilted, the workpiece W is shaking, etc.

[0417] When the inclination of the conveying direction of the workpiece W is to be obtained, as shown in FIG. Fig.58 As shown, the acquisition can be performed using the first distance sensor 31A and the second distance sensor 31B arranged side by side in the up-down direction. When two different points in the height direction of the workpiece W are measured by the first distance sensor 31A and the second distance sensor 31B, the tilt abnormality of the workpiece W relative to the plotter 2 can be measured, and the abnormality can be determined in the inspection device 500 for the abnormal value.

[0418] Fig.59 1 is a flowchart showing an example of the inspection process in the case where the first distance sensor 31A and the second distance sensor 31B are provided to perform pass / fail determination. Steps S501 to S503 are respectively Fig.56 The steps S301 to S303 shown are the same. In step S504, the measurement value Y1 generated by the first distance sensor 31A is acquired. In step S505, the determination unit 514b determines whether Y1 is abnormal, that is, whether the measurement value Y1 generated by the first distance sensor 31A exceeds the predetermined range. When it is determined that Y1 is normal (the measurement value generated by the first distance sensor 31A is within the predetermined range), the processing proceeds to step S507. When it is determined in step S505 that Y1 is abnormal (the measurement value generated by the first distance sensor 31A is outside the predetermined range), the processing proceeds to step S506, and the determination unit 514b records the Y1 abnormality in the storage unit 513, etc., and then the processing proceeds to step S507.

[0419] In step S507, the measurement value Y2 generated by the second distance sensor 31B is acquired. In step S508, the determination unit 514b determines whether Y2 is abnormal, that is, whether the measurement value Y2 generated by the second distance sensor 31B exceeds the predetermined range. When it is determined that Y2 is normal (the measurement value generated by the second distance sensor 31B is within the predetermined range), the process proceeds to step S510. When it is determined that Y2 is abnormal (the measurement value generated by the second distance sensor 31B is outside the predetermined range) in step S508, the process proceeds to step S509, and the determination unit 514b records the abnormality of Y2 in the storage unit 513, etc., and then the process proceeds to step S510.

[0420] In step S510, the determination unit 514b calculates the inclination of the workpiece W. In step S511, the determination unit 514b determines whether the inclination of the workpiece W calculated in step S510 exceeds a predetermined range. When it is determined that the inclination of the workpiece W is normal (within a predetermined range), the process proceeds to step S513. When it is determined in step S511 that the inclination of the workpiece W is abnormal (outside a predetermined range), the process proceeds to step S512, and the determination unit 514b records the abnormal inclination of the workpiece W in the storage unit 513, etc., and then the process proceeds to step S513. Steps S513 to S517 are respectively related to Fig.54 The steps S106, S108, S109, S110 and S111 shown are the same.

[0421] In step S518 , the inspection device 500 sends the distance Y1 abnormality record in step S506 , the distance Y2 abnormality record in step S509 , the tilt abnormality record in step S512 , and the transfer speed abnormality record in step S515 to the plotter 2 .

[0422] Fig.60 is a flowchart showing an example of the inspection process in the case where the first distance sensor 31A and the second distance sensor 31B are provided. Steps S601 to S606 are respectively Fig.59 In step S607, the pass / fail determination unit 514a determines the tilt abnormality of the workpiece W, and proceeds to step S608 for determination of "failure" in the case of tilt abnormality, and proceeds to step S609 in the case of "pass".

[0423] In step S609, the pass / fail determination unit 514a determines whether the distance Y1 is abnormal, and proceeds to step S610 to determine "failure" in the case of Y1 being abnormal, and proceeds to step S611 in the case of "pass". In step S611, the pass / fail determination unit 514a determines whether the distance Y2 is abnormal, and proceeds to step S612 to determine "failure" in the case of Y2 being abnormal, and proceeds to step S613 in the case of "pass".

[0424] In step S613, the pass / fail determination unit 514a performs determination on the transmission speed abnormality, proceeds to step S614 for determination of "failure" in the case of the transmission speed abnormality, and proceeds to step S615 for determination of "pass". Steps S615 and S616 are respectively Fig.55 Steps S211 and S212 are the same.

[0425] In addition, in the case where the pass / fail determination unit 514a performs the pass / fail determination of the drawing state, the user can select whether to use one or both of the measurement results of the conveying speed and the distance of the workpiece W. For example, a selection screen may be displayed to receive a selection of the conveying speed and / or the distance. In addition, the threshold for determining an abnormality may be set in advance or may be set by the user. That is, the user can freely select whether to use an initial setting value determined according to the performance of the drawing machine 2 or to use a value set by the user in consideration of the installation noise (the influence of wind, etc.) in the user's environment as a threshold for determining an abnormality in the conveying speed and the distance of the workpiece W.

[0426] (Function and Effect)

[0427] According to the present embodiment, when the inkjet printer 1 is installed, a measurement value related to the position or movement of the workpiece W conveyed by the conveyor 10 can be generated by the optical movement measuring sensor 30 or the distance sensor 31. Since the measurement value generated by the optical movement measuring sensor 30 or the distance sensor 31 includes the positional relationship between the print head 24 and the workpiece W, the moving speed, the moving amount, etc. of the workpiece W, it is possible to obtain information on the installation state of the inkjet printer 1 based on the measurement value generated by the optical movement measuring sensor 30 or the distance sensor 31. Therefore, the user does not need to perform trial drawing and adjustment multiple times, and usability at the time of installation is improved.

[0428] In addition, when drawing various types of information on the workpiece W conveyed by the conveyor 10, a measurement value related to the movement of the workpiece W in the conveying direction is generated by the optical movement measurement sensor 30. Based on the measurement value and the reference position information of the workpiece W, the current offset position relative to the reference position of the workpiece W can be acquired. When the ink ejection from the print head 24 is controlled based on the acquired current offset position and drawing data, the influence of errors due to changes in the conveying line speed, changes in the position of the workpiece W in the width direction, and sliding of the workpiece W is suppressed, thereby suppressing the occurrence of drawing failure.

[0429] When the drawing process is performed, the evaluation unit 40h evaluates the reliability of the measurement performed by the optical movement measuring sensor 30. For example, when the amount of received light received by the optical movement measuring sensor 30 is less than a predetermined value, an abnormality process may be performed by determining that the reliability does not satisfy a predetermined standard. That is, when the reliability of the measurement by the optical movement measuring sensor 30 does not satisfy a predetermined standard, an abnormality process may be performed at an appropriate time, thereby suppressing the occurrence of a large number of drawing failures.

[0430] In addition, the distance to the workpiece W can be measured by the distance sensor 31, and ink ejection can be controlled based on the determination result as to whether the distance to the workpiece W satisfies a predetermined standard. Therefore, for example, in the case where the distance to the workpiece W is too long and a drawing failure may occur, this situation can be handled, thereby suppressing the occurrence of a drawing failure.

[0431] In addition, when an event related to the drawing state occurs during the operation of the drawing machine 2, the event may cause the occurrence of a drawing failure. In this regard, a measurement value related to the position or movement of the workpiece W conveyed by the conveyor 10 is acquired, and the event detection unit 45 detects an event related to the drawing state that occurs during the operation of the drawing machine 2 based on the acquired measurement value. In response to the event being detected, information about the measurement value generated by the optical movement measuring sensor 30 or the distance sensor 31 and information about the event are stored in association with at least a part of the drawing data, and therefore, the cause of the occurrence can be analyzed, including whether the event is caused by the position or movement of the workpiece W, and what kind of drawing state is obtained by confirming the stored content after the event occurs.

[0432] The above embodiments are merely examples in all aspects and should not be interpreted as limiting. In addition, all modifications and changes belonging to the equivalent scope of the claims fall within the scope of the present invention.

[0433] As described above, the present disclosure can be used, for example, when various types of information are drawn on packaging materials such as corrugated cardboard.

Claims

1. An inkjet printer that ejects ink to draw information on an object conveyed by a conveyor, the inkjet printer comprising: an ink tank storing the ink; a nozzle configured to eject ink supplied from the ink tank toward a drawing target object; a storage unit storing drawing data specifying ejection timing of the nozzle at each of a plurality of offset positions in the conveying direction, the ejection timing corresponding to the drawing information; an optical movement measurement sensor that receives light from the drawing target object and generates a measurement value related to movement of the drawing target object in the conveying direction based on the received light; as well as A drawing control unit that controls ink ejection from the nozzle based on reference position information indicating that a reference position of the drawing target object is at a predetermined position, a current offset position relative to the reference position based on the measurement value generated by the optical movement measurement sensor, and the drawing data.

2. The inkjet printer according to claim 1, wherein The reference position information is a timing signal indicating that the drawing target object conveyed by the conveyor has reached a predetermined position.

3. The inkjet printer according to claim 2, further comprising: a timing signal output unit, the timing signal output unit outputting the timing signal, The drawing control unit acquires the timing signal output from the timing signal output unit as the reference position information.

4. The inkjet printer according to claim 2, wherein The optical movement measuring sensor generates the timing signal indicating that the drawing target object has reached the predetermined position based on a change in the amount of light received, and The drawing control unit acquires the timing signal generated by the optical movement measuring sensor as the reference position information.

5. The inkjet printer according to claim 1, wherein The optical movement measuring sensor includes a light projecting unit that projects light onto the drawing target object and a light receiving unit that receives a speckle pattern generated by the light projected from the light projecting unit according to characteristics of a surface shape of the drawing target object and generates light reception data including the speckle pattern, and generates the measurement value based on an amount of movement of the speckle pattern included in the light reception data generated by the light receiving unit.

6. The inkjet printer according to claim 1, further comprising: a movement amount acquisition unit that acquires a movement amount caused by the conveyor, When the accuracy of the measurement value generated by the optical movement measuring sensor is less than or equal to a predetermined value, the drawing control unit controls the ejection of ink from the nozzle based on the movement amount acquired by the movement amount acquisition unit and the drawing data.

7. The inkjet printer according to claim 1, further comprising: a movement amount acquisition unit that acquires a movement amount caused by the conveyor, wherein the drawing control unit determines whether the measurement value generated by the optical movement measurement sensor exceeds a threshold value, and controls ink ejection from the nozzle based on the movement amount acquired by the movement amount acquisition unit and the drawing data until the measurement value exceeds the threshold value, and when the measurement value exceeds the threshold value, controls ink ejection from the nozzle based on the current offset position and the drawing data.

8. The inkjet printer according to claim 1, wherein The optical movement measuring sensor measures the movement amount of the drawing target object in a direction perpendicular to the conveying direction, and The drawing control unit controls ink ejection from the nozzle based on an amount of movement in a direction perpendicular to the conveying direction measured by the optical movement measuring sensor.

9. The inkjet printer according to claim 1, wherein The optical movement measurement sensor generates measurement values ​​of two axes orthogonal to each other, and determines a measurement value related to the movement in the conveying direction based on the generated measurement values ​​of the two axes.

10. The inkjet printer according to claim 1, further comprising: a transmission direction identification unit, the transmission direction identification unit identifying the transmission direction, The drawing control unit controls ink ejection from the nozzle based on the conveying direction identified by the conveying direction identification unit.

11. The inkjet printer according to claim 10, The inkjet printer is configured such that a hydraulic head pressure of a liquid level of ink stored in the ink tank is applied to the nozzle as negative pressure, and The inkjet printer is installed so that the liquid level is within a predetermined inclination range relative to a horizontal plane.

12. The inkjet printer according to claim 11, wherein The drawing control unit controls ink ejection from the nozzle so as to draw the information in parallel with the conveying direction when the conveying direction recognized by the conveying direction recognition unit is inclined with respect to the horizontal plane.

13. The inkjet printer according to claim 1, further comprising: a housing, wherein the nozzle is arranged in the housing, The optical movement measuring sensor is fixed to the housing in such a manner that the positional relationship with the nozzle is a predetermined positional relationship.

14. The inkjet printer according to claim 1, wherein The nozzle has a plurality of ejection ports formed along a first direction, and The optical movement measuring sensor is arranged at a position offset from the nozzle along the conveying direction, and is installed so that the position of the drawing target area pointed to by the nozzle in the first direction and the position of the area where the current offset position is measured by the optical movement measuring sensor in the first direction at least partially overlap with each other.

15. The inkjet printer according to claim 1, wherein The nozzle includes a first nozzle and a second nozzle, the first nozzle is provided in a first housing and has a plurality of ejection ports, the second nozzle is provided in a second housing that can be arranged separately from the first housing and has a plurality of ejection ports, The storage unit includes drawing data for the first nozzle and drawing data for the second nozzle as the drawing data, and The drawing control unit controls ink ejection from the plurality of ejection ports formed in the first nozzle based on the current offset position and the drawing data for the first nozzle, and controls ink ejection from the plurality of ejection ports formed in the second nozzle based on the current offset position and the drawing data for the second nozzle.

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