Printing apparatus and printing method

Abstract

A printing apparatus (10) for printing on a substrate and a method of operating such a printing apparatus (10), the printing apparatus (10) comprising a printhead (24) and a monitoring device (40) operable to detect movement of a target surface (T) relative to the printhead (24); wherein the target surface (T) is intended to move substantially parallel to the first axis (x), and the monitoring device (40) is operable to detect movement of the target surface (T) along a second axis (y), the second axis (y) being substantially perpendicular to the first axis (x).

Description

Technical Field

[0001] The present invention relates to a printing device, and in particular but not exclusively, to a transfer printing device, and a method of monitoring one or more parameters of said printing device. Background Art

[0002] Transfer printing is well known in the commercial printing field. An ink-carrying strip or ribbon travels along a ribbon path from a supply reel past a print head to a take-up reel, the print head being operable to transfer ink from the ribbon to a substrate. The printing device may be installed in a production line, for example, adjacent to the substrate.

[0003] The print head may include heat-energizable printing elements or pixels operable to heat the ink on the ribbon such that the ink can be removed from the ribbon and transferred to the substrate to form an image, such as data, patterns, barcodes, two-dimensional codes, etc. One or both of the supply reel and the take-up reel are typically driven to convey the ribbon between the reels.

[0004] The ribbon can typically move between the reels in two directions, i.e., forward and backward directions. The substrate onto which the ink is to be transferred can typically move relative to the print head during the printing operation. There are two main operating modes - intermittent printing and continuous printing. In intermittent printing, the substrate advances to a printing position close to the print head and then stops, and then the print head moves relative to the substrate, for example by moving a print head carriage, to transfer ink from the ribbon to the substrate to produce an image. Then the substrate advances to the next printing position. The printing operation process is typically repeated until all required printing operations have been completed, and / or the ink ribbon is exhausted and / or the substrate is exhausted. In continuous printing, the substrate moves relative to the print head substantially continuously, while the print head remains in a substantially fixed lateral position relative to the substrate support. In this case, the lateral movement (or lack thereof) of the print head refers to a movement substantially parallel to the direction of movement of the substrate. In both the intermittent printing mode and the continuous printing mode, the print head typically moves in a longitudinal direction towards and away from the ribbon and the substrate between a non-printing position and a printing position, in the non-printing position, the print head does not contact the ribbon (or at least is not close enough to be able to transfer ink from the ribbon), and in the printing position, the print head contacts the ribbon (or at least is close enough to transfer ink from the ribbon). The non-printing position may include a plurality of positions, the plurality of positions including a ready-to-print position and a retracted position that may be required (e.g., for maintenance purposes).

[0005] It is important to be able to precisely control the speed of the ribbon relative to the speed of the substrate in order to optimize the print quality. In some cases, it is beneficial to precisely control the speed of the ribbon to correspond to the speed of the substrate, for example to prevent ink contamination and / or to ensure that ink is present on the portion of the ribbon adjacent to the print head to avoid failed or low-quality prints. The speed of the ribbon can be different from the speed of the substrate, but can be related to the speed of the substrate. The speed of the ribbon can be slower than the speed of the substrate. Therefore, it is desirable to monitor the speed of the ribbon and / or the substrate.

[0006] It is desirable to be able to precisely determine the position of the print head, for example relative to the ribbon and / or the substrate. This enables the print head drive means responsible for positioning the print head relative to the ribbon and / or the substrate not to cause, for example, excessive or insufficient pressure to be applied during the printing operation, and also ensures that the print head does not contact other components of the printing device and / or does not contact the ribbon and / or the substrate and / or the substrate support at the wrong position. If the print head movement is misaligned, for example in the lateral direction along the ribbon path or in a direction perpendicular to the ribbon path but in a plane substantially the same as the ribbon path, the resulting image may be incorrectly positioned on the substrate or may be incomplete. Incorrect positioning of the print head may, for example, result in damage to the print head, and / or damage to other components of the printing device and / or inappropriate print quality. It is known to determine the pressure applied by the print head on the ribbon / substrate by using a pressure measuring element. When the pressure measuring element detects that a predetermined pressure has been reached or exceeded, the pressure measuring element determines that the print head has contacted the ribbon / substrate.

[0007] If the printing device is not installed correctly (for example, the substrate support and the substrate travel path are not parallel) or the ribbon in the ribbon cassette is not wound correctly (i.e., conical movement or telescopic movement occurs), the ribbon may "track" across the print head (instead of always being positioned under the print head). By tracking is meant moving perpendicular to the overall travel direction of the substrate within the plane of the substrate. For example, referring to the attached Figure 3 and 5 , this is a movement in the axial y direction.

[0008] For example, a 32 mm print head is typically paired with a 33 mm ribbon, so if the ribbon tracks (along the y-axis) by more than 0.5 mm, the print head may be directly exposed to the substrate, causing additional wear, early failure and poor print quality.

[0009] Tracking or misalignment of the substrate relative to the printing device (such as the print head and / or the ribbon) may also cause problems of incomplete or poor-quality printing, and / or may cause damage to the printing device, the ribbon, the substrate and / or the components of the production line on which the printing device is installed.

[0010] If the printing device is not installed to be well aligned with the advancing direction of the substrate, during the printing operation, when the print head presses the ribbon against the substrate, the substrate may pull the ribbon significantly away from the print head, resulting in wear on the print head, especially at the ends. The printing device and method herein seek to minimize the tracking of the substrate and / or the ribbon.

[0011] If the ribbon is wound by hand, or the ribbon cassette has fallen, for example resulting in non-parallelism of the rollers / guides / axles, some tracking may occur when the ribbon is transferred from the supply reel to the take-up reel or vice versa. SUMMARY OF THE INVENTION

[0012] Embodiments related to the present application seek to alleviate one or more problems associated with existing systems.

[0013] A printing device for printing on a substrate is provided, including a print head and a monitoring device operable to detect movement of a target surface relative to the print head, wherein the target surface is intended to move substantially parallel to a first axis, and the monitoring device is operable to detect movement of the target surface along a second axis, the second axis being substantially perpendicular to the first axis.

[0014] The monitoring device is operable to detect movement of the target surface along the first axis and the second axis.

[0015] The monitoring device is operable to simultaneously detect movement along the first axis and the second axis.

[0016] The printing device may include a processor operable to determine one of a linear displacement or an angular displacement of a part of the printing device relative to the target surface.

[0017] The printing device may include a processor operable to determine one of a linear displacement or an angular displacement of a part of the print head relative to the target surface.

[0018] The printing device may include a processor operable to process data indicative of movement of the target surface along the first axis and the second axis to determine an angular displacement of the print head relative to the target surface.

[0019] The monitoring device is operable to observe an interference pattern generated by radiation reflected by the target surface.

[0020] The target surface may be one of a substrate on which the printing device is arranged to print and one of a substrate and a ribbon associated with the printing device and operable to transfer ink to the substrate.

[0021] The target surface may be a component whose movement indicates the movement of at least one of a substrate on which the printing device is arranged to print and a ribbon associated with the printing device and operable to transfer ink to the substrate to be printed.

[0022] Movement of the component indicates movement of the substrate and / or the ribbon, and can be one of the substrate support and the ribbon guide.

[0023] The printing device is operable in response to an indication of movement of the target surface along a second axis and / or an indication of displacement of a part of the printing device relative to the target surface, where the response can include at least one of the following:

[0024] a. Providing an indication to the user that movement along the second axis is occurring or has occurred;

[0025] b. Providing an indication to another device that movement along the second axis is occurring or has occurred;

[0026] c. Automatically adjusting the position of the printing device relative to the target surface by moving at least one of the following:

[0027] i. A part of the printing device,

[0028] ii. The entire printing device,

[0029] iii. The target surface;

[0030] d. Adjusting the printing operation instructions to account for the movement or displacement;

[0031] e. Stopping or pausing the printing operation.

[0032] The printing device can include a plurality of monitoring devices.

[0033] The printing device can be a thermal transfer printer.

[0034] A method of operating a printing device for printing on a substrate, including a print head and a monitoring device operable to detect movement of a target surface relative to the print head; where the target surface is intended to move substantially parallel to a first axis and the monitoring device is operable to detect movement of the target surface along a second axis substantially perpendicular to the first axis, the method including using the monitoring device to detect movement of the target surface along the second axis.

[0035] The method of operating the printing device can include:

[0036] - Using the monitoring device to monitor at least one of the following:

[0037] ○ Movement of the target surface along the second axis;

[0038] ○ Displacement of a part of the printing device relative to the target surface;

[0039] - Provide an indication of the movement of the target surface along the second axis and / or an indication of the displacement of a part of the printing device relative to the target surface to the processor of the printing device;

[0040] - In response to the indication of movement or displacement, where the response includes at least one of the following:

[0041] ○ Provide an indication to the user that movement along the second axis or displacement of a part of the printing device is occurring or has occurred;

[0042] ○ Provide an indication to another device that movement along the second axis is occurring or has occurred;

[0043] ○ Automatically adjust the position of the printing device relative to the target surface by moving at least one of the following:

[0044] ■ A part of the printing device;

[0045] ■ The entire printing device;

[0046] ■ The target surface;

[0047] ○ Adjust the printing operation instructions to account for the movement or displacement;

[0048] ○ Stop or pause the printing operation.

[0049] The method may include considering known or intentional movement or displacement of at least a part of the printing device relative to the target surface along the first axis and / or the second axis.

[0050] The target surface may be the substrate to be printed, and the method may include using an indication that the substrate has moved and / or is moving and / or is being displaced relative to the print head along the second axis to indicate that a ribbon associated with the printing device for transferring ink to the substrate has moved and / or is moving and / or is being displaced relative to the print head. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] For a better understanding of the present application, preferred embodiments thereof will now be described by way of example only with reference to the accompanying drawings, in which:

[0052] Figure 1 is an illustrative cross-sectional view of a printing device;

[0053] Figure 2 is Figure 1 an enlarged illustrative view of a monitoring device of the printing device and the target surface;

[0054] Figure 3 is an illustrative perspective view of a print head adjacent to a substrate to be printed, showing possible displacement directions of the print head and / or the target surface;

[0055] Figure 4 is Figure 1 a perspective view of a part of a printing apparatus;

[0056] Figure 5 is a perspective view of a part of a printing apparatus according to an embodiment of the present technology;

[0057] Figure 6 is a schematic view of the angular displacement of the print head relative to the target surface. DETAILED DESCRIPTION

[0058] Referring to the accompanying drawings, there is shown a printing apparatus 10 having a body 11 that houses a first reel 12 and a second reel 14 that contain a ribbon or a color ribbon 16. Each of the reels 12, 14 is mounted on a respective mandrel 18, 20. Each of the first mandrel 18 and the second mandrel 20 can be driven by a ribbon drive device 22, which can include one or more motors. Rotation of each mandrel 18, 20 causes rotation of the corresponding reel 12, 14 and can be controlled to transfer the ribbon 16 from one of the first reel 12 and the second reel 14 to the other of the first reel 12 and the second reel 14. The ribbon 16 can be transferred between the reels 12, 14 in two directions, namely, a forward direction and a reverse direction. The rotation of the mandrel 18, 20 and / or the reel 12, 14 can be controlled and / or monitored in any suitable manner, such as according to known methods, for example, by a single motor or respective motors for each mandrel 18, 20, etc. The printing apparatus 10 can be a printing and applying apparatus, for example, operable to print labels for application to another object, or operable to print directly onto a product package, such as overprinting.

[0059] The ribbon drive device 22 is operable to transfer the ribbon 16 between one of the first and second reels 12, 14 and the other of the first and second reels 12, 14, past the print head 24. A ribbon support 17 (such as a ribbon roller) can support the ribbon 16 near the print head 24. The print head 24 can include a plurality of energizable printing elements, such as thermally energizable printing elements, which can be selectively operated to transfer ink from the ribbon 16 to a substrate 26. The substrate 26 can be a roll of material, such as paper, film (such as biaxially oriented polypropylene), labels, etc. The substrate 26 can be provided as discrete items to be printed, such as labels, as in printing and applying applications.

[0060] The substrate 26 can be supported by a substrate support 28 adjacent to the print head 24. For example, the substrate support 28 can be a paper feed roller or a substantially flat paper press. The substrate support 28 can be driven by a substrate drive device 29 (such as a motor) to advance the substrate 26. It can be understood that the substrate drive device 29 does not need to be positioned within the substrate support 28 and / or does not need to directly drive the substrate support 28. The substrate support 28 can be rotated to move the substrate 26 relative to other parts of the printing device 10 (such as the print head 24). The substrate drive device 29 can be operated to advance the substrate 26 to a printing position adjacent to the print head 24. Although the substrate drive device 29 is provided to move the substrate mainly in the lateral direction x, the substrate drive device 29 (and / or additional / alternative substrate drive devices, not shown) can be operated to move the substrate 26 in one or more directions and / or Figure 3 as shown in each of the axes x, y, z.

[0061] The printing device 10 can include a controller 30. The controller 30 can be operated to control one or more functions of the printing device 10. For example, the controller 30 can be operated to control the movement of the ribbon 16, such as by controlling the ribbon drive device 22, the movement of the print head 24, and / or the energization of the printing elements of the print head 24 to control the movement of the ribbon 16. The controller 30 can be operated to monitor the parameters and / or functions of the printing device 10. For example, the controller 30 can be operated to receive signals indicating the functions and / or parameters of the printing device 10. For example, the controller 30 can be operated to determine and / or monitor the diameter of each reel 12, 14 and / or determine and / or monitor the tension in the ribbon 16, for example. It should be understood that these examples are not intended to be limiting, and any combination of the functions of the controller 30 that enables the printing device 10 to perform a printing operation is possible.

[0062] The printing device 10 can include a monitoring device 40. The monitoring device 40 is shown in Figure 2 exemplary form.

[0063] The monitoring device 40 can be operated to monitor one or more parts of the printing device 10 (such as the print head 24 and / or the ribbon 16), and / or one or more parameters or characteristics of an article (such as the substrate 26) cooperating with the printing device 10.

[0064] The monitoring device 40 can include a non-contact sensor. The monitoring device 40 can include a transmitter 42 and a receiver 44. The monitoring device 40 can include a processor 46, such as a microprocessor. The transmitter 42, the receiver 44, and the processor 46 can be integrated in a single device (such as a single integrated circuit or chip).

[0065] The transmitter 42 can be operated to emit an output signal S o . The output S omay be or include electromagnetic radiation. The output S of the transmitter 42 o may include coherent light. For example, the transmitter 42 may be or include a laser. The output of the transmitter 42 may be in the infrared range of the electromagnetic spectrum. The monitoring device 40 may include a vertical cavity surface emitting laser (VCSEL). A series of output signals may be emitted. The output signal S o may be a pulsed signal. Between each output signal S emitted o there may be a time interval t. The output signal S o may be emitted at a substantially constant frequency, and the interval t between each output is substantially the same. The time interval t between successive output signals S o may nominally be substantially constant, but it should be understood that it may be necessary to identify and account for jitter.

[0066] The output signal S of the transmitter 42 o may be directed towards a target surface T, the parameters of which are to be determined and / or monitored.

[0067] The target surface T may be part of the printing device 10, an item cooperating with the printing device 10, or an item separate from the printing device 10.

[0068] The receiver 44 of the monitoring device 40 may be configured to receive all or part of the output signal S from the transmitter 42 o The receiver 44 may be configured to receive the signal output S from the transmitter 42 o of the reflected portion S R . For example, the receiver 44 may be a CCD or CMOS device. The transmitter 42 may be located adjacent to the receiver 44. The receiver 44 may partially or completely surround the transmitter 42.

[0069] The monitoring device 40 may be a microchip. The monitoring device 40 may include integrated digital image processing circuitry. The monitoring device 40 may be a surface mountable component. The monitoring device 40 may be a motion detector. The monitoring device 40 may be a laser scatter motion detector. The monitoring device 40 may be of the lensless type. The monitoring device 40 may be selected to have a depth of field (DOF) suitable for positioning the monitoring device 40 within the printing device. For example, the depth of field of the monitoring device 40 may be selected to be in the range of 5 mm to 60 mm.

[0070] A plurality of monitoring devices 40 may be associated with the printing apparatus 10. Each monitoring device 40 may be provided to monitor a specific characteristic or parameter. A plurality of parameters and / or characteristics may be monitored by one or more monitoring devices 40. Each parameter or characteristic to be monitored may be monitored by one monitoring device 40 or a plurality of monitoring devices 40. The number of monitoring devices 40 required to monitor a specific parameter / characteristic may depend on the parameter / characteristic to be monitored and / or the target surface T, and may be selected accordingly. The monitoring device 40 may be positioned in or near the print head 24. The or each monitoring device 40 may communicate with the controller 30. For simplicity, a single monitoring device 40 is generally referred to herein, but such references may, where appropriate, cover the use of a plurality of monitoring devices 40.

[0071] The monitoring device 40 may be operable to measure a change in the position of the target surface T relative to the monitoring device 40, i.e., the monitoring device 40 may be operable to monitor the displacement of the target surface T. For example, the monitoring device 40 may be operable to monitor the displacement of the substrate 26 and / or the ribbon 16 relative to the monitoring device 40 and / or relative to another part of the printing apparatus 10.

[0072] The monitoring device 40 may be operable to determine the speed of the target surface T. The speed of the target surface T may be an absolute speed or may be a speed relative to another part of the printing apparatus 10 (such as the print head 24 and / or the monitoring device 40).

[0073] The monitoring device 40 may be operable to determine a change in the position of the target surface T. The target surface T has a reflectivity R T . The reflectivity R T may not be constant, in other words, different regions of the target surface may have different reflectivity values. The reflectivity of the surface may also vary over time, for example, the reflectivity of the ribbon 16 may depend on the amount of ink on the ribbon and thus the reflectivity R T of a portion of the ribbon may have one value before the ink has been removed during a printing operation and a different reflectivity R T after the ink has been removed. The texture or roughness of the target surface T may affect the reflectivity R T and / or the signal or pattern reflected by the target surface T.

[0074] In use, the monitoring device 40 may be operable to acquire successive surface images (frames) of the target surface T and, by comparing two or more frames with each other (e.g., by autocorrelation, cross-correlation or convolution, or using Fourier analysis in the detector plane), determine one or more of the speed, direction and magnitude of the movement of the target surface T relative to the monitoring device 40. This method will be described in more detail below.

[0075] The monitoring apparatus 40 is operable to perform a series of monitoring operations to generate displacement data. During a first monitoring operation, the transmitter 42 is configured to transmit a first output signal S towards the target surface T. o , and the receiver 44 is configured to receive the output signal S reflected by the target surface T o The reflected part S R The reflected part S R The generated reflected portion S is a pattern (e.g., a speckle pattern) R The data can be stored by the processor 46. A series of monitoring operations can be performed. The monitoring operation can be performed multiple times per second, for example, thousands of times per second. In each monitoring operation, the transmitter 42 is configured to transmit an output signal S toward the target surface T. o , and the receiver 44 is configured to receive the output signal S corresponding to each o The corresponding reflected part S R . Reflection part S R Reflected by the target surface T and having the characteristics of the portion toward which the output of the target surface T is directed and reflected by it. Each reflected portion S R It can be an interference pattern (e.g. a speckle pattern). Comparing the interference patterns enables the determination and / or monitoring of parameters of the target surface T. R The generated pattern or as each reflected part S R The data of the features may be stored, for example as images or frames, or in any suitable manner.

[0076] The monitoring device 40 is operable to report movement of the target surface T during a monitoring period, e.g., a change in position or displacement in one or more dimensions x, y, and z since the last monitoring operation / reading. A monitoring period can be one or more time intervals t; in other words, a monitoring period can include multiple monitoring operations. Changes in position data (i.e., displacements) of the target surface T relative to the monitoring device 40 can be provided to a controller (e.g., controller 30). Changes in position data determined by the monitoring device 40 and transmitted to the controller 30 can be read by the controller 30. The monitoring device 40 can automatically transmit data to the controller 30, e.g., based on a duty cycle and / or in response to a triggering event. Additionally or alternatively, the controller 30 can interrogate the monitoring device 40 to obtain data related to parameter changes. Interrogation of the monitoring device 40 by the controller 30 can be automatic, e.g., based on a duty cycle and / or in response to a triggering event. The term "read" is intended to indicate the receipt of data from the monitoring device 40 by the controller 30, regardless of whether the controller 30 has interrogated the monitoring device 40 or whether the monitoring device 40 has automatically transmitted data, e.g., based on a predetermined schedule or in response to a triggering event.

[0077] The monitoring device 40 is operable to determine that the change in a parameter since the last monitoring operation or during a monitoring cycle has been zero. The monitoring device 40 is operable to indicate to the controller 30 that the change in a parameter since the last monitoring operation or during a monitoring cycle has been zero. The non - change of a parameter since the last monitoring operation or during a monitoring cycle can be a trigger event. The change in a parameter after a cycle of non - change of the parameter can be a trigger event. Thus, the monitoring cycles can have approximately the same duration or can have different durations. The controller 30 and / or the monitoring device 40 can determine or set the duration of each monitoring cycle.

[0078] The change in parameter data (e.g., the displacement of the target surface T relative to the monitoring device 40) can be summed by the processor 46, and the summed value can be transmitted to the controller 30. The change in position data in two dimensions can be provided. During the same monitoring cycle or time interval t, the change in one dimension can be zero while the change in position in the other dimension can be non - zero. The monitoring device 40 is operable to indicate that it has detected a change in a parameter, e.g., when it has detected movement (displacement) of the target surface T in at least one dimension. For example, if the target surface T is stationary for a period of time, the monitoring device 40 can perform multiple monitoring operations during that period and will not detect displacement. The monitoring device 40 may not transmit data related to the time during which the target surface is stationary to the controller 30. If, at the end of the time period during which the target surface is stationary, the monitoring device 40 detects that the target surface has moved in at least one dimension, the change can trigger the monitoring device 40 to transmit data related to the change in position (displacement) to the controller 30. The controller 30 is operable to use a single data indicating the change, e.g., data indicating that the target surface T has moved a distance d in at least one of the dimensions x, y, z during the most recent time interval. The time interval can be set by the monitoring device 40.

[0079] By performing monitoring operations and / or readings at regular intervals, the speed of the target surface T can be calculated since the frequency of the monitoring operations and / or the sampling (reading) frequency of the controller 30 for the data provided by the monitoring device 40 is known. The controller 30 that receives the change in position data can process the data and use the change in the parameter (e.g., position) data to control aspects of the printing process and the operation of the printing device. The time interval between each monitoring operation of the monitoring device and / or the time interval between each sampling (reading) by the controller 30 can or cannot be the same. The clock of the controller 30 can be synchronized with the clock of the monitoring device 40 in order to be able to perform precise calculations, e.g., to determine the rotational and / or translational displacement of the target surface T relative to the monitoring device 40 or its derivatives, e.g., speed, acceleration, and jerk in multiple dimensions.

[0080] The displacement data obtained by the monitoring device 40 can be sent to the controller 30 and used by the controller 30 when calculating other parameters / characteristics of the printing device 10 and / or related articles (such as the substrate 26), and / or can be used to determine the control function of the printing device 10 so that the printing operation can be performed.

[0081] As briefly explained above, the parameters or characteristics can be monitored by multiple monitoring devices 40. The monitoring array can include multiple monitoring devices 40. Each monitoring device 40 in the monitoring array can be spaced less than 10 mm, such as 6 mm, from one or more adjacent monitoring devices 40. The multiple monitoring devices 40 can be arranged in any suitable manner. The arrangement of the multiple monitoring devices 40 can be a straight line, a rectangular array, a substantially circular array, etc. The arrangement and / or type of the monitoring devices 40 in the monitoring array can depend on the target surface T to be monitored and / or the parameters of the target surface T to be monitored.

[0082] Multiple monitoring arrays can be provided. The multiple monitoring arrays can be used to monitor multiple target surfaces and / or multiple parameters, and / or provide indication data that can be used to determine one or more other parameters. When referring to the monitoring device 40 herein, those skilled in the art can understand that a single monitoring device 40 can be used or a monitoring array can be used. The most appropriate arrangement of the monitoring device 40 can be selected according to the available space, and / or the parameters / characteristics to be monitored, and / or the required monitoring accuracy, and / or the target surface T to be monitored. For example, a monitoring array can be used to optimally monitor a matte target surface to provide sufficiently accurate data indicating the surface parameters (it should be understood that this is only a suggestion of one possibility and not an indication of the basic features).

[0083] In the case of providing a monitoring array, the controller 30 can be used to distinguish between the data provided by each monitoring device 40 of the monitoring array. The controller 30 can be used to combine some or all of the data from the monitoring devices 40 in the monitoring array to determine other parameters of the target surface and / or determine the control function of the printing device 10 so that the printing operation can be performed.

[0084] The target surface T pointed to by the signal of the monitoring device 40 can be the substrate 26. The monitoring device 40 can be used to determine the displacement and / or velocity and / or acceleration of the substrate 26 and / or the orientation of the substrate 26 relative to a part of the printing device 10 (such as the print head 24). In this case, the monitoring device 40 can be positioned within the main body 11 of the printing device 10. Alternatively, the monitoring device 40 can be positioned outside the main body 11 of the printing device 10. The monitoring device 40 can be spaced between approximately 10 mm and approximately 40 mm from the substrate 26. The monitoring device 40 can be positioned such that the output signal S o emitted by the monitoring device 40 onto the substrate 26 has an incident angle θi is approximately 90°. The monitoring device 40 can be mounted on or in the print head 24. The monitoring device 40 can be positioned at or near the center line of the print head 24. The monitoring device 40 can be positioned such that the output signal S of the monitoring device 40 or each output signal S o is incident on the substrate 26 at a position substantially aligned with one or more printing elements of the print head 24. The monitoring device 40 can be positioned such that the output signal S o is directed towards the top or upper dead point position of the substrate support 28. The method for determining the characteristics (such as displacement, velocity, acceleration) of the substrate 16 is as described above. The monitoring device 40 can be positioned on the print head carriage 25.

[0085] The target surface T can be the ribbon 16. The monitoring device 40 can directly determine and / or monitor the displacement and / or velocity of the ribbon 16. The monitoring device 40 can be mounted within the body 11 of the printing device 10. The monitoring device 40 can be positioned such that the output signal S emitted by the monitoring device 40 onto the ribbon 16 o has an incident angle θ i of approximately 90°. The monitoring device 40 can be positioned near the center line of the ribbon 16. The monitoring device 40 can be positioned such that the output signal S o is directed towards the center line of the ribbon 16. The printing device 10 can be configured to operate with different types (such as different widths) of the ribbon 16. The monitoring device 40 can be positioned such that the output signal S o is directed towards the center line of the narrowest ribbon 16 that the printing device 10 is configured to use. The monitoring device 40 can be mounted on or near the print head 24 to determine the parameters of the ribbon 16 at or near the print head 24. The method for determining the characteristics (such as displacement, direction, velocity and / or acceleration) of the ribbon 16 is generally as described above and is related to the substrate 26.

[0086] The monitoring device 40 can be positioned adjacent to one of the first and second reels 12, 14. The monitoring device 40 can be associated with each of the first and second reels 12, 14. The or each monitoring device 40 can provide an indication of the displacement (i.e., rotation) of the associated reel 12, 14 and / or an indication of the rotational speed of the associated reel 12, 14. This can include determining the displacement and / or rotational speed of the outer surface of the ribbon 16. The linear displacement of the ribbon 16 near the or each reel 12, 14 can be monitored. Such linear displacement can indicate the amount of ribbon 16 wound or unwound from the associated reel 12, 14. The rotational angle of the reels 12, 14 can be known, so the diameter of the reel can be calculated from the monitored linear displacement of the ribbon 16 near the reel. The monitoring device 40 can be operative to determine the rotational displacement of the outer surface of one or both of the reels 12, 14 in order to determine the circumference of the or each reel 12, 14. The determination of the rotational speed and / or diameter of the or each reel 12, 14 can be performed as a calibration step. The determination of the rotational speed and / or diameter of the or each reel 12, 14 can be made over a very short time interval, which can be the time taken for a few millimeters (e.g., less than 10 mm) of the ribbon 16 to be wound and / or unwound from one of the reels 12, 14. This enables the diameter of the reels 12, 14 to be determined almost instantaneously. This reduces the time taken to perform the calibration process and eliminates the need to convey the ribbon 16 in both directions. The ability of the monitoring device 40 to directly monitor properties / parameters such as displacement means that the determination of the properties of the or each reel 12, 14 can be made during the operation of the printing device 10 rather than during a calibration step. The monitoring of the properties can be carried out continuously (i.e., repeatedly) or substantially continuously during the use of the printing device 10. During the use of the printing device 10, such monitoring can replace or supplement the calibration step.

[0087] The ability of the or each monitoring device 40 to directly determine the properties / parameters of the or each reel 12, 14 means that no auxiliary components (e.g., monitoring rollers and / or Hall effect sensors) are required to determine, for example, the relative speed of the reels 12, 14. Additionally, these embodiments do not require a cassette insertion / removal switch, but can track the lateral (axial) movement of the reels / ribbon. The speed of one or each of the reels 12, 14 (and / or the relative speed of the reels 12, 14, and / or a signal indicative of the speed of each reel 12, 14) can be transmitted to the controller 30. The controller 30 can use this information related to the speed of the or each reel 12, 14 to determine the control of the ribbon drive, such as determining the control of the motor drive circuit of the ribbon drive device 22.

[0088] The monitoring device 40 is operable to determine characteristics of the print head 24, such as position, displacement, and / or velocity. The monitoring device 40 is operable to determine the displacement of the print head 24 relative to another part of the printing apparatus 10, for example. In this case, the monitoring device 40 may be in a fixed position relative to the print head 24, such as attached to the print head 24 or the carriage 25, and the target surface T may be another part of the printing apparatus 10, such as a part of the body 11. Alternatively, the monitoring device 40 may be mounted on a (preferably fixed) part of the printing apparatus 10, such as the body 11, and the target surface T may be a part of the print head 24. This is useful in determining whether the print head 24 is in the correct position relative to the ribbon 16 and / or the substrate 26 and / or one or more other parts of the printing apparatus 10 (e.g., the substrate support 28).

[0089] Reference Figure 5 and Figure 6 , now let's look at the case where the monitoring device 40 determines that there is a deviation in the relative positioning of the printing apparatus 10 (e.g., the print head 24 and / or the ribbon 16) and the substrate 26, such as an angular deviation, and / or a cumulative distance error in the position of the substrate 26 in a direction substantially perpendicular to the substrate path (i.e., along the y-axis).

[0090] In an embodiment, the y-axis data from the monitoring device 40 can be used to detect non-parallelism between the plane (main plane) of the printing apparatus and the travel path of the substrate 26. Note Figure 5The position of the arrow labeled 1 in the figure marks the location where the monitoring device 40a can interact with the substrate 26, which is consistent with the above methods and configurations. It is understood that other positions of the monitoring device 40a may be suitable. Any non-zero data received from the monitoring device 40 on the y-axis can be an indication of non-parallelism. In other words, if the monitoring device 40 determines a change in the position of the substrate 26 in the y direction (i.e., in a direction substantially perpendicular to the path of the substrate), the monitoring device 40 (such as the monitoring device 40) can provide an output to the controller 30 or other processor to indicate that the printing device 10 and the substrate 26 are no longer aligned. The deviation or misalignment can be indicated as a linear misalignment, an angular deviation, or the amount of deviation predicted over a given time period, length, number of printing operations, etc. There can be a tolerance associated with the alignment of the substrate 26 and the printing device 10 such that a certain amount of misalignment or deviation can be acceptable. This tolerance can depend on the application in which the printing device 10 is used. The controller 30 can be operable to provide a signal to the user that the printing device 10 and the substrate 26 are misaligned or about to become misaligned. An indication can additionally or alternatively be provided to another device, such as a controller or actuator configured to adjust the position of the printing device relative to other devices (such as a production line). When the misalignment is within an acceptable tolerance, an indication of the misalignment can be provided, for example, to enable a remedial step to be performed before the misalignment exceeds the tolerance. This indication can be provided so that a remedial step can be performed before the misalignment is too large to continue the printing operation.

[0091] During installation, the setup interface can prompt the installation engineer to start the substrate 26 rolling, i.e., moving past the printing device 10 (specifically past the print head 24). The x, y outputs of the monitoring device 40 can be used to detect significant non-zero y data. Such data is an indication of non-parallelism between the printing device 10 and the ideal substrate travel path, e.g., an indication of the deviation between the ideal substrate path and the actual substrate path y. The angular deviation θ can be derived almost simply by using the following relationship:

[0092]

[0093] or

[0094]

[0095] The sub-millimeter resolution achievable by the monitoring device 40 should be able to read sub-precision. In other words, a deviation θ of less than 1° can be detected by the monitoring device 40.

[0096] Visualization can be provided to the engineer to indicate that they adjust the position, such as rotating the printing device / support or the base of the paper press, to correct the angle between the printing device 10 and the substrate 26 until it is correct - determined when the y data averages to zero during a typical printing cycle as expected. Additionally or alternatively, if the deviation or misalignment exceeds a predetermined limit, the printing operation can be interrupted.

[0097] During normal use, the monitoring process can run in the background, notifying / warning the maintenance engineer (or remote service team) that some tracking error has occurred, such as indicating misalignment (misalignment or deviation) from the original installation position, or falling outside a predetermined tolerance. Then, if the customer deems this to be a problem, it can be remedied. Data from the monitoring device 40 can be queried and used, for example, to diagnose print quality, print head dot damage, or reported ribbon tracking problems by studying the average y-axis value of the data observed in a recent time period. In the case where the print head 24 is mounted at a non-right angle θ relative to the substrate, the angle of installation can be determined.

[0098] In an embodiment, for example, a monitoring device 40b located at the position indicated by the arrow 2 in Figure 5 can be used to track ribbon installation problems. Even if the printing device 10 is perfectly installed such that the print head 24 is perfectly perpendicular to the path of the substrate 26, problems where the ribbon 16 is incorrectly installed in the cassette or incorrectly wound onto the core can cause tracking problems. If the cassette has been dropped, there may also be a problem with the verticality of the guide rollers (around which the ribbon 16 extends in the ribbon path between the reels 12, 14) to the cassette or the substrate, which can force the ribbon 16 to deviate from its desired path.

[0099] To detect these problems, the monitoring device 40 can observe the ribbon 16, and the y data can be used to ensure that the y data averages to zero. This can be checked in each printing cycle, i.e., to determine whether the user has correctly installed the ribbon 16 and that the ribbon 16 has not tracked on the print head 24 since the last print. It can also be checked over multiple printing cycles, for example, to detect whether the ribbon 16 has moved left or right (i.e., along the y-axis) on the print head 24 during, for example, the last 1 m of conveyance, which can be continuously tracked. This is particularly useful immediately after the cassette is reinserted into the printing device 10. [[ID=1,2]]

[0100] This or each monitoring device 40 can provide 16-bit data (i.e., potentially 1 / 65k resolution) for each dimension (x, y, z).

[0101] The user can be notified via the interface of the printing device 10 that the ribbon 16 is poorly wound, that they need to replace the cassette, and / or they can confirm that tracking has occurred and simply ignore the warning.

[0102] In some installations, the printing device 10 can move orthogonally (e.g., along the y-axis) between print cycles to allow for optimized ribbon usage. This is referred to as "translation". If the substrate 26 moves while the printing device 10 is translating, any non-orthogonal movement of the substrate 26 cannot be distinguished from the translation. For example, if the printing device moves 10 mm to the left in 10 milliseconds between prints, and the substrate 26 has a net leftward movement of 1 mm in the same time, the sensor will only measure a 9 mm movement. The advantage of this is that the printing device 10 can command an additional 1 mm movement to ensure the net relative movement is the desired 10 mm. A separate sensor is not required to distinguish substrate drift from printing device translation because the integrated encoder (monitoring device 40) will accumulate the relative movement.

[0103] The monitoring device 40 can provide "distance moved" information, eliminating the need to attach an external encoder to the translation mechanism. This provides a solution where the printing device 10 can provide distance information to the control system managing the printing device translation, and the printing device 10 can drive actuators such as robotic arm electronics to manage a more translation-based radial ribbon saving process. Note that in this case, even for continuous printing applications where a curved surface (i.e., the impression roller) is observed, since the movement is along the flat y-axis of the roller, the sensed speed is the correct / true speed independent of the position of the monitoring device 40 relative to the impression roller.

[0104] As described above, between the print cycles of a thermal transfer overprinting (TTO) device, the entire TTO printing device 10 can be translated by the equivalent width of the printed image (i.e., the print head moves relative to the substrate and the ribbon). In other words, the entire printing device 10 can move a distance in a direction substantially perpendicular to the substrate path (transverse to the substrate travel direction), which can be equal to the size of the printed image, to ensure that when different parts of the ribbon 16 and the print head 24 are used, the printed image is located at the same position on the substrate 26 (e.g., a packaging film). This is referred to as radial ribbon saving (RRS).

[0105] It has been observed that when the ribbon is slack, after the print head 24 is lifted, the substrate 26 can come into contact with the ribbon 16. This can cause ribbon 16 tracking, i.e., moving substantially perpendicular to the expected ribbon path. This can occur when the printing device 10 has indicated that it has completed a print cycle, but the ribbon tension has not yet been reset.

[0106] In cases where the printing device uses a mechanical tension adjustment mechanism, a quick response is typically provided when the print head is lifted to compensate for the slack. However, other devices are more prone to ribbon tracking, where, for example, software is responsible for maintaining tension control via a motor, which typically has an inherently slower response time.

[0107] Observing the substrate 26 using one or more monitoring devices 40 enables detection of misalignment between the printing device 10 (e.g., the print head 24) and the substrate 26.

[0108] In this way, we solve the problem that the printing device 10 does not know when it has been translated and thus cannot inform its controller (especially in high-speed RRS applications) that ribbon tracking may occur.

[0109] A related problem is misalignment between the ribbon roller 17 / substrate 26 and the printing device 20. This is particularly important for continuous applications of printing long images. In this case, even a small misalignment manifests as a significant pull, i.e., we can find that a visually imperceptible misalignment of 0.5 degrees between the print head and the substrate / roller results in a 1 mm drag, i.e., displacement / deformation of a 100 mm image.

[0110] The present invention solves the problem of detecting such misalignment, thus avoiding ribbon tracking and its impact on cut printing.

[0111] In an embodiment of a continuous / combined printing device provided with one or more monitoring devices 40, an optical sensor (laser scattering sensor) as described above can be positioned on or near the print head carriage 25. Positioning the monitoring device 40 at this physical location is advantageous such that the interaction with the substrate support 28 / substrate 26, i.e., the observation of the substrate support 28 / substrate 26, is as close as possible to the print head 24. In an embodiment of an intermittent printing device, each monitoring device 40 can be placed further away from the print head 24, with the main requirement being that it can monitor the substrate 26.

[0112] The monitoring device 40 is operable to monitor the substrate 26. This can detect movement in terms of distance using information about displacement, or the angle θ between the substrate 26 and a part of the printing device 10 (e.g., the print head 24), abbreviated as arctan(x / y) in degrees, where x and y are the distances moved within a given time range (see Figure 6 ). It should be understood that this relationship can be used to determine the angle θ between any target surface T and the printing device 10 (e.g., the print head 24).

[0113] The movement component of the substrate 26 along the y-axis and / or an indication of misalignment relative to the print head 24 can indicate that the ribbon 16 has also moved / has moved and / or is misaligned relative to the print head at a corresponding angle or distance.

[0114] In some cases, the substrate 26 may not necessarily be misaligned, but since the monitoring device 40 can detect movement substantially perpendicular to the path of the substrate 26 and / or the ribbon 16, this information can be cross-correlated with the status of the ribbon tension (and / or print head lift) to determine the probability of ribbon tracking. For example, in an RRS application, detecting a lateral (y-axis) substrate movement component while we have not yet re-tensioned the ribbon can indicate ribbon tracking.

[0115] In such a case, the monitoring device 40 can indicate the occurrence and potential cause of potential ribbon tracking, for example via an interface, since the controller 30 (for example) will determine that there is insufficient time for the RRS responsible movement elapsed between the end of the print cycle and the y-axis movement. An appropriate response can be executed. The printing device 10 can then be reconfigured to take this into account. The reconfiguration can include manual adjustment and / or automatic adjustment and / or calibration.

[0116] In the presence of misalignment, the monitoring device 40 can monitor any y-axis movement of the substrate 26 relative to the printing device 10 and correlate it with the print cycle status. In other words, if the substrate moves laterally during a print operation, it may have dragged the ribbon 16 across the print head 24.

[0117] This feature can then be used for:

[0118] a. Notifying the operator of the misalignment, for example via a user interface:

[0119] i. For example, in units of mm / print unit, such as due to the substrate, having a lateral ribbon shear of 1 mm per print may result in a trimming of 0.5 mm;

[0120] ii. For example, in degrees (such as a 1-degree deviation), such that the installation engineer (or user) can correct the deviation, for example, by adjusting the positioning of the printing device 10 and / or adjusting the ribbon 16;

[0121] b. Stopping the printing device;

[0122] c. Providing a warning to the user;

[0123] d. Adjusting the print instructions, for example, by adding an offset to the print position and / or orientation to avoid image trimming. For example, during setup / power-on, the operator / image designer may need to consent to such an automatic adjustment; and / or

[0124] e. Providing an indication to another device (such as an actuator) that is configured to adjust the position or orientation of the printing device (or a part of the printing device) so that the movement / shift can be corrected.

[0125] For an intermittent printing device, since the print head 24 can move (return to its print-ready position) while the substrate 26 is being driven forward, the control system (e.g., controller 30) also needs to take into account the movement of the print head carriage 25.

[0126] The monitoring or observation of the target surface T can involve monitoring data that is invisible to the human eye, such as monitoring an interference pattern generated by reflected radiation, rather than a pattern marked on the target surface T itself. No special markings, heads, or tails on the target surface are required - the data being monitored can be data obtained from any part of the target surface T, including available portions of the target surface, such as printable or printed areas of the substrate, inked portions of the ribbon, or portions of the ribbon from which ink has been removed. There is no need to store reference data in a look-up table or the like in order to determine the movement of the target surface T; a comparison between readings is necessary, but this is different from, for example, a comparison with expected data.

[0127] The setup process for installing the printing device can be simplified due to the simplicity of checking that the printing device is correctly configured for the ribbon to travel along the correct path without tracking. Additionally, complexity can be reduced in applications where the printing device is translated (physically moved laterally) to optimize the printing position in a radial ribbon-saving mode, which has an inherent complexity between external components of the printing device (such as actuators, robotic arms, or linear motors), the printing device, and the encoder (or other monitoring device) of the actuator, which determines the extent to which the printing device needs to be translated between prints.

[0128] Deviation correction during printer use can be directly or indirectly notified to the user, and / or can be corrected based on indications of movement, deviation, misalignment, and / or based on indications that movement, misalignment, deviation may fall outside a threshold.

[0129] The printing operation can be adjusted to take into account possible or actual tracking of the substrate and / or ribbon and / or incorrect positioning of part or all of the printing device, such as misalignment, deviation, as a supplement or alternative to error correction.

[0130] As used in this specification and the claims, the terms "comprising" and "including" and their variants are meant to include the specified features, steps, or integers. These terms should not be construed as excluding the presence of other features, steps, or components.

[0131] The invention can also broadly consist of the components, elements, steps, examples, and / or features separately or jointly mentioned or pointed out in the specification, and these components, elements, steps, examples, and / or features can be any combination of two or more of the said components, elements, steps, examples, and / or features. In particular, one or more features in any embodiment described herein can be combined with one or more features from any other embodiment described herein.

[0132] Protection may be sought for any combination of any features disclosed in any one or more of the publications cited herein with the content of the present application.

[0133] Although certain exemplary embodiments of the invention have been described, the scope of the appended claims is not intended to be limited to these embodiments. The claims should be interpreted literally, purposively, and / or by inclusion of equivalents.

Claims

1. A printing device for printing on a substrate, comprising a print head and a monitoring device operable to detect movement of a target surface relative to the print head; wherein the target surface is intended to move substantially parallel to a first axis, and the monitoring device is operable to detect movement of the target surface along a second axis, the second axis being substantially perpendicular to the first axis.

2. The printing device according to claim 1, characterized in that, The monitoring device is operable to detect movement of the target surface along the first axis and the second axis.

3. The printing device according to claim 2, characterized in that, The monitoring device is operable to simultaneously detect movement along the first axis and the second axis.

4. The printing device according to any one of the preceding claims, comprising a processor operable to determine one of a linear displacement or an angular displacement of a part of the printing device relative to the target surface.

5. The printing device according to claim 4, characterized in that, The part of the printing device is the print head.

6. The printing device according to any one of the preceding claims, characterized in that, Comprising a processor operable to process data indicative of movement of the target surface along the first axis and the second axis to determine an angular displacement of the print head relative to the target surface.

7. The printing apparatus according to any one of the preceding claims, characterized in that, The monitoring device is operable to observe an interference pattern generated by radiation reflected by the target surface.

8. The printing device according to any one of the preceding claims, characterized in that, The target surface is one of a substrate on which the printing device is arranged to print and an ink ribbon associated with the printing device and operable to transfer ink to the substrate.

9. The printing device according to any one of the preceding claims, characterized in that, The target surface is a component whose movement indicates movement of at least one of a substrate on which the printing device is arranged to print and an ink ribbon associated with the printing device and operable to transfer ink to the substrate to be printed.

10. The printing apparatus according to claim 9, wherein, The component is one of a substrate support and a ribbon guide.

11. The printing apparatus according to any one of the preceding claims, characterized in that, It is operable in response to an indication of movement of the target surface along the second axis, and / or an indication of displacement of a part of the printing device relative to the target surface, wherein the response comprises at least one of the following: a. Providing an indication to the user that movement along the second axis is occurring or has occurred; b. Providing an indication to another device that movement along the second axis is occurring or has occurred; c. Automatically adjusting the position of the printing device relative to the target surface by moving at least one of the following: i. A part of the printing device, ii. The entire printing device, iii. The target surface; d. Adjusting the printing operation instructions to account for the movement or displacement; e. Stopping or pausing the printing operation.

12. The printing apparatus according to any one of the preceding claims, characterized in that, Comprising a plurality of monitoring devices.

13. The printing apparatus according to any one of the preceding claims, characterized in that, The printing device is a thermal transfer printer.

14. A method of operating a printing device for printing on a substrate, comprising a print head and a monitoring device operable to detect movement of a target surface relative to the print head; wherein, The target surface is intended to move substantially parallel to a first axis, and the monitoring device is operable to detect movement of the target surface along a second axis, the second axis being substantially perpendicular to the first axis, the method comprising using the monitoring device to detect movement of the target surface along the second axis.

15. The method of operating a printing device according to claim 11, as claimed in claim 14, wherein, The method comprises: a. Using the monitoring device to monitor at least one of the following: i. Movement of the target surface along the second axis; ii. Displacement of a part of the printing device relative to the target surface; b. Provide an indication of the movement of the target surface along the second axis to the processor of the printing device, and / or an indication of the displacement of a part of the printing device relative to the target surface; c. In response to the indication of movement or displacement, wherein the response includes at least one of the following: i. Provide an indication to the user that movement along the second axis or displacement of a part of the printing device is occurring or has occurred; ii. Provide an indication to another device that movement along the second axis is occurring or has occurred; iii. Automatically adjust the position of the printing device relative to the target surface by moving at least one of the following: ■ A part of the printing device, ■ The entire printing device; ■ The target surface; iv. Adjust the printing operation instructions to account for the movement or displacement; v. Stop or pause the printing operation.

16. The method according to claim 15, characterized in that Including considering known or intentional movement or displacement of at least a part of the printing device relative to the target surface, along the first axis and / or the second axis.

17. The method according to any one of claims 14 to 16, characterized in that, The target surface is the substrate to be printed, and the method includes using an indication that the substrate has moved and / or is moving and / or is displaced relative to the print head along the second axis to indicate that a ribbon associated with the printing device for transferring ink to the substrate has moved and / or is moving and / or is displaced relative to the print head.

Images