Control System

Abstract

To provide a technique for properly moving movable bodies at high speed in a system for controlling the movable bodies that process an object.SOLUTION: In a system 1 of one aspect of the present disclosure, movable bodies 11, 12 are driven by a motor 13 to move in a passageway, and in the moving process, they process an object. A controller 32 controls a motor on the basis of speed measured by measuring units 14, 34, using a feedback control system, so that the movable bodies move at a speed according to a speed profile from a moving start point to a target stop point. The controller controls the speed of the movable bodies by controlling the motor in a feed-forward control system, instead of the feedback control system, in a re-accelerating segment where the movable bodies accelerate from a first speed to a second speed.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to control systems. [Background technology]

[0002] In inkjet printers, a technique is known for increasing the movement speed of a carriage carrying an inkjet head in non-image areas between image areas, thereby speeding up processing (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2005-22115 A Summary of the Invention [Problem to be solved by the invention]

[0004] In a system that processes an object by moving a carriage carrying a processing head, the position and speed of the carriage are measured by, for example, reading an encoder scale with a sensor that moves together with the carriage. The measured position and speed are used to control the movement of the carriage.

[0005] If an obstruction that impedes reading is present on the encoder scale, measurement using this encoder scale cannot be performed normally, at least when the carriage and the sensor pass through an area corresponding to the location of the obstruction. For example, when the processing head is an inkjet head, if the encoder scale is stained with ink, the stain will impede normal reading of the encoder scale.

[0006] This interruption in reading can make it difficult to control the carriage appropriately. In particular, when the carriage is moving at high speed, even a short interruption can cause a large control error, making it difficult to control the carriage's movement appropriately. There can be cases where a measuring instrument cannot accurately measure the moving state of a moving object to be controlled for various reasons, not limited to encoders.

[0007] Therefore, according to one aspect of the present disclosure, it is desirable to provide a technique that can appropriately move a moving object at high speed in a system for controlling the moving object that processes an object. [Means for solving the problem]

[0008] According to one aspect of the present disclosure, there is provided a control system including a motor, a moving body, a measuring instrument, and a controller, wherein the moving body is driven by the motor to move on a passageway and is configured to process an object during the movement.

[0009] The measuring device is configured to measure a speed of the moving object, and the controller is configured to control the motor based on the speed measured by the measuring device in a feedback control manner so that the moving object moves from a movement start point on the passage to a target stopping point at a speed that follows the speed profile.

[0010] The speed profile defines an acceleration section in which the moving body transitions from the start point of movement to a constant speed state, a deceleration section in which the moving body transitions from the constant speed state to a target stopping point, and a target speed in an intermediate section between the acceleration section and the deceleration section.

[0011] The intermediate section includes a first constant speed section, a second constant speed section, and a non-constant speed section. In the first constant speed section, the moving body moves at a constant first speed. In the second constant speed section, the moving body moves at a constant second speed higher than the first speed. In the non-constant speed section, the moving body moves at a non-constant speed. In the first constant speed section, the moving body operates to process the object.

[0012] In a non-constant speed section, that is, a re-acceleration section in which the moving body accelerates from a first speed to a second speed after passing through a first constant speed section, the controller controls the speed of the moving body by controlling the motor with a feedforward control method instead of a feedback control method.

[0013] Feedback control is susceptible to the effects of errors when the speed measured by a measuring instrument contains a large error. In particular, in non-constant speed sections, it is difficult to appropriately correct the measurement value and the motor operation amount considering the error in the speed measured by the measuring instrument compared to constant speed sections. When accelerating a moving object at a high speed range such as in a re-acceleration section, the effect of measurement errors can have a significant impact on the stability of control.

[0014] In the re-acceleration section, by controlling the motor with a feedforward control method as in the control system of the present disclosure, it is possible to suppress unstable control that may occur when the speed measurement error by the measuring device is large in the re-acceleration section. Therefore, according to one aspect of the present disclosure, in a system for controlling a moving body that processes an object, it is possible to appropriately move the moving body at high speed. [Brief description of the drawings]

[0015] [Figure 1] FIG. 1 is a block diagram illustrating a configuration of an image forming system. [Diagram 2] FIG. 2 is a diagram illustrating the configuration of a printing mechanism and a linear encoder. [Diagram 3] FIG. 11 is an explanatory diagram of dirt adhering to a linear scale. [Figure 4] 4 is a flowchart showing a main process executed by a processor. [Diagram 5] 4 is a flowchart showing a printing process executed by a processor. [Figure 6] 6A and 6B are graphs illustrating different types of velocity profiles. [Figure 7]4 is a flowchart showing a motor control process executed by a CR motor control unit for each control period. [Figure 8] 4 is a flowchart showing a section control process executed by a CR motor control unit. [Figure 9] 11 is a flowchart showing a correction process repeatedly executed by a linear encoder processing unit. [Figure 10] 13 is a flowchart showing a motor control process in a first modified example. [Figure 11] 10 is a flowchart showing a motor control process in a second modified example. [Figure 12] 13 is a flowchart showing a speed profile setting process executed by a processor in a third modified example. [Figure 13] 13 is a flowchart showing a standard speed profile generation process executed by a processor in a third modified example. [Figure 14] 14A and 14B are graphs illustrating different types of velocity profiles. [Figure 15] FIG. 15A is a diagram illustrating a speed profile corrected by extending a constant speed section, and FIG. 15B is a diagram illustrating a speed profile corrected by deleting a high speed section. [Figure 16] FIG. 16 is a diagram for explaining a speed profile corrected by extending the constant speed section. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Exemplary embodiments of the present disclosure will now be described with reference to the drawings. The image forming system 1 of this embodiment shown in Fig. 1 is configured as an inkjet printer. The image forming system 1 includes a recording head 11, a carriage 12, a carriage (CR) motor 13, and a linear encoder 14. The recording head 11, the carriage 12, the CR motor 13, and the linear encoder 14 form a part of a printing mechanism 15, the details of which are shown in Fig. 2.

[0017] The print mechanism 15 is configured to receive power from a CR motor 13 to move a carriage 12 carrying the recording head 11 in a main scanning direction. The main scanning direction is a direction perpendicular to the sub-scanning direction in which the paper P is transported.

[0018] The recording head 11 is an ejection head configured to eject ink droplets, and is a so-called inkjet head. When the carriage 12 moves across the paper P in the main scanning direction, the recording head 11 executes an ink droplet ejection operation to form an image on the paper P. The CR motor 13 is a DC motor, and functions as a drive source for reciprocating the carriage 12.

[0019] The linear encoder 14 is an incremental type optical linear encoder, and is used to measure the position and speed in the main scanning direction of the carriage 12. The position and speed of the carriage 12 correspond to state quantities that represent the moving state of the carriage 12, in other words, motion parameters.

[0020] The image forming system 1 further includes a line feed (LF) motor 21 and a rotary encoder 22 (see FIG. 1) to convey the paper P. The LF motor 21 is a DC motor, and functions as a drive source for rotating a conveying roller (not shown) that conveys the paper P in the sub-scanning direction. The rotary encoder 22 is an incremental type optical rotary encoder, and is used to measure the amount of rotation and the rotation speed of the conveying roller.

[0021] The image forming system 1 further includes a head driver 18, a CR motor driver 19, an LF motor driver 29, and an ASIC 2 for driving and controlling the recording head 11, the CR motor 13, and the LF motor 21. The head driver 18 drives the recording head 11 in accordance with a control signal input from the ASIC 2 to cause the recording head 11 to eject ink droplets.

[0022] The CR motor driver 19 drives and rotates the CR motor 13 in accordance with a control signal input from the ASIC 2. The LF motor driver 29 drives and rotates the LF motor 21 in accordance with a control signal input from the ASIC 2.

[0023] The ASIC 2 is configured to control the ink droplet ejection operation by the recording head 11, the transport operation of the carriage 12 by the CR motor 13, and the transport operation of the paper P by the LF motor 21, by inputting control signals to each of the drivers 18, 19, and 29. The ASIC 2 includes a recording control unit 31, a CR motor control unit 32, an LF motor control unit 33, a linear encoder processing unit 34, and a rotary encoder processing unit 35.

[0024] Here, a specific configuration of the printing mechanism 15 included in the image forming system 1 will be described with reference to Fig. 2. The printing mechanism 15 includes a guide shaft 41 in the main scanning direction that defines the path of the carriage 12. The carriage 12 is inserted through this guide shaft 41.

[0025] The carriage 12 is further connected to an endless belt 42 provided along the guide shaft 41. The endless belt 42 is wound between a driving pulley 43 provided at one end of the guide shaft 41 and a driven pulley 44 provided at the other end of the guide shaft 41.

[0026] The drive pulley 43 is rotationally driven by the CR motor 13 to rotate the endless belt 42. The carriage 12 moves in the main scanning direction along the guide shaft 41 by the power of the CR motor 13 transmitted through the rotation of the endless belt 42.

[0027] A linear scale 46 serving as an encoder scale is disposed near the guide shaft 41 along the guide shaft 41. An optical sensor 47 including a light emitting unit 50 and a light receiving unit 60 is mounted on the carriage 12.

[0028] The linear encoder 14 is composed of this optical sensor 47 and linear scale 46. The detailed configuration of the optical sensor 47 is shown in a dashed balloon in the lower right of Fig. 2. As shown in the figure, the linear scale 46 has slits 48 arranged at predetermined intervals in the longitudinal direction corresponding to the main scanning direction. The slits 48 may be holes, or may be made of a transparent material that can transmit light. The light-emitting unit 50 and the light-receiving unit 60 that make up the optical sensor 47 are arranged to sandwich the linear scale 46.

[0029] The light-emitting section 50 includes two light-emitting elements 51, 52, specifically, an A-phase light-emitting element 51 and a B-phase light-emitting element 52. The light-receiving section 60 includes two light-receiving elements 61, 62 corresponding to the two light-emitting elements 51, 52, specifically, an A-phase light-receiving element 61 and a B-phase light-receiving element 62. Light emitted from the A-phase light-emitting element 51 is received by the A-phase light-receiving element 61, and light emitted from the B-phase light-emitting element 52 is received by the B-phase light-receiving element 62.

[0030] The optical sensor 47 is fixed to the carriage 12, and moves in the main scanning direction along the linear scale 46 in conjunction with the carriage 12. Due to this movement, the optical sensor 47 moves relatively to the linear scale 46 in the main scanning direction.

[0031] The light receiving states of the light receiving elements 61, 62 change due to a change in the relative position between the optical sensor 47 and the linear scale 46. The optical sensor 47 outputs two types of pulse signals according to the change in the light receiving state as encoder signals.

[0032] That is, the optical sensor 47 outputs two types of pulse signals having a predetermined phase difference (90 degrees in this embodiment) in response to the movement of the carriage 12. The first pulse signal is an A-phase signal corresponding to the light receiving state of the A-phase light receiving element 61, and the second pulse signal is a B-phase signal corresponding to the light receiving state of the B-phase light receiving element 62.

[0033] The linear encoder processing unit 34 determines the moving direction of the carriage 12 based on the above-mentioned A-phase signal and B-phase signal input as encoder signals from the linear encoder 14, and measures the position and speed of the carriage 12. The linear encoder processing unit 34, together with the linear encoder 14, functions as a measuring instrument for the position and speed of the carriage 12. The measured values ​​of the position and speed of the carriage 12 are input to the recording control unit 31 and the CR motor control unit 32.

[0034] The position and speed of the carriage 12 are measured based on at least one of the A-phase signal and the B-phase signal. For ease of explanation, an example will be described in which the position and speed of the carriage 12 are measured based on the A-phase signal.

[0035] According to this example, the linear encoder processing unit 34 detects the rising edge and the falling edge of the A-phase signal input from the linear encoder 14. Every time such an edge is detected, the count value of a position counter (not shown) is updated. This count value corresponds to the measurement value of the position of the carriage 12.

[0036] The linear encoder processor 34 measures the speed of the carriage 12 based on the time from when the previous edge is detected to when the current edge is detected, i.e., the edge interval, in synchronization with the detection timing of each edge of the A-phase signal. The speed is proportional to the inverse of the edge interval.

[0037] The recording control unit 31 generates a control signal for the recording head 11 based on the measurement values ​​input from the linear encoder processing unit 34, and inputs the generated control signal to the head driver 18. The head driver 18 drives the recording head 11 in accordance with the control signal input from the recording control unit 31, thereby causing the recording head 11 to eject ink droplets according to the position of the carriage 12.

[0038] The CR motor control unit 32 calculates an operation amount U for the CR motor 13 for each predetermined control period based on the measurement value input from the linear encoder processing unit 34. The operation amount U is an operation amount that specifies the power to be applied to the CR motor 13, and in particular, is a voltage command value that specifies the voltage to be applied to the CR motor 13.

[0039] The CR motor control unit 32 inputs a PWM signal for applying power corresponding to the calculated operation amount U to the CR motor 13 to the CR motor driver 19 as a control signal for the CR motor 13 .

[0040] The CR motor driver 19 drives the CR motor 13 in accordance with a control signal input from a CR motor control unit 32. Driven by the CR motor 13, the carriage 12 and the recording head 11 move in the main scanning direction.

[0041] The rotary encoder 22 is configured to output two types of pulse signals having a predetermined phase difference (90 degrees in this embodiment) as encoder signals in response to rotation of the LF motor 21. The encoder signals are input to a rotary encoder processing unit 35 of the ASIC 2.

[0042] The rotary encoder processing unit 35 measures the rotation amount and rotation speed of the transport roller that transports the paper P based on the encoder signal input from the rotary encoder 22. These measurement values ​​are input to the LF motor control unit 33.

[0043] In order to control the rotation of the conveyance roller, the LF motor control unit 33 calculates an operation amount for the LF motor 21 for each predetermined control period based on the measurement value input from the rotary encoder processing unit 35. Then, as a control signal for the LF motor 21, a PWM signal for applying power corresponding to the calculated operation amount to the LF motor 21 is input to the LF motor driver 29.

[0044] The LF motor driver 29 drives the LF motor 21 in accordance with a control signal input from the LF motor control unit 33. Driven by this LF motor 21, the transport roller rotates, and the paper P is transported in the sub-scanning direction.

[0045] The image forming system 1 further includes a processor 3, a ROM 4, a RAM 5, an EEPROM 6, a communication interface (I / F) 7, and a user interface (I / F) 8, which are connected to the ASIC 2 via a bus 9.

[0046] The processor 3 is configured to comprehensively control each unit of the image forming system 1. The ROM 4 stores a computer program executed by the processor 3. The RAM 5 is used as a work area when the computer program is executed by the processor 3. The EEPROM 6 is an electrically rewritable non-volatile memory, and stores information that should be retained even after the image forming system 1 is turned off.

[0047] The communication interface 7 is configured to be capable of communicating with an external device such as a personal computer, etc. The user interface 8 includes an operation unit that can be operated by a user, and a display unit that can display various information to the user.

[0048] Incidentally, in the image forming system 1 of the present embodiment, if dirt 70 adheres to the linear scale 46 of the linear encoder 14, the position and speed of the carriage 12 may not be measured correctly.

[0049] 3, dirt 70 is attached to a partial area of ​​the linear scale 46. The slits 48 present in that area are covered with dirt 70. Light from the light-emitting elements 51, 52 does not reach each of the light-receiving elements 61, 62 through the slits 48 covered with dirt 70.

[0050] In this way, the stain 70 can be an obstacle to the optical sensor 47 reading the slits 48 of the linear scale 46 by emitting and receiving light. The stain 70 can be caused by the adhesion of grease, ink, paper powder, and the like to the linear scale 46.

[0051] The lower part of Fig. 3 shows an example of an encoder signal output from the optical sensor 47 when the optical sensor 47 passes at a constant speed over the dirty linear scale 46 shown in the upper part of Fig. 3. The shown encoder signal may be understood as an A-phase signal or a B-phase signal. According to this example, the edge interval of the encoder signal, which should be equal under normal circumstances, increases threefold when the optical sensor 47 passes over dirt 70.

[0052] In this embodiment, as described above, the speed of the carriage 12 is measured based on the edge interval. Therefore, the fluctuation in the edge interval caused by the stain 70 causes a discontinuous error in the measured speed value. This measurement error leads to a deterioration in the control accuracy when controlling the speed of the carriage 12.

[0053] Therefore, in this embodiment, the presence or absence and position of an area where dirt 70 is attached is estimated, and the control method of the carriage 12 is switched depending on the presence or absence and position of the dirt 70. As described above, the area where dirt 70 is attached is an area where reading of the slit 48 and normal measurement are hindered. Therefore, the movement range of the carriage 12 where the optical sensor 47 reads the area where dirt 70 is attached is referred to as the "hindering area" hereinafter.

[0054] The inhibition region is the relative movement range of the optical sensor 47 with respect to the linear scale 46, and corresponds to the movement range of the optical sensor 47 that reads the portion of the linear scale 46 on which the stain 70, which acts as an inhibitor preventing normal reading, is attached.

[0055] In this embodiment, the optical sensor 47 reads the linear scale 46 from a position perpendicular to the surface of the linear scale 46. Therefore, the inhibition area corresponds to the movement range of the carriage 12 in which the optical sensor 47 is located in front of the area of ​​the linear scale 46 where the stain 70 is attached.

[0056] 4, which is executed by the processor 3 when the image forming system 1 is started by powering on or canceling the sleep mode. When the main process starts, the processor 3 executes a pre-scan process to estimate an inhibition region (S110).

[0057] In the pre-scan process, the processor 3 instructs the ASIC 2 to reciprocate the carriage 12 from one end of the movable range to the other end of the movable range. Based on this instruction, the CR motor control unit 32 executes drive control for the CR motor 13 to reciprocate the carriage 12 from one end of the movable range to the other end of the movable range.

[0058] In the prescan process, the CR motor 13 is controlled so that the carriage 12 moves at a constant speed, except for necessary acceleration and deceleration. This control is performed based on the deviation E=Vr-V between the target speed Vr and the measured speed value V. The measured speed value V is a measured value of the speed of the carriage 12 obtained from the linear encoder processing unit 34. A speed abnormality of the carriage 12 is detected on condition that the deviation E exceeds a threshold value in a section where the carriage 12 moves at a constant speed. In the prescan process, an inhibition area of ​​the linear scale 46 is estimated based on this speed abnormality.

[0059] An example of a method for estimating the inhibition area has already been disclosed by the applicant. For example, the position of the inhibition area is estimated based on the count value of a position counter, which is the position measurement value X of the carriage 12 measured by the linear encoder processing unit 34 when the speed abnormality of the carriage 12 is detected.

[0060] For example, when the carriage 12 is moved from a first end point of the movable range to a second end point, a first count value of the position counter from the start of the movement to when a speed abnormality is detected is detected.

[0061] Furthermore, a second count value of the position counter from the start of movement to the detection of the speed abnormality when the carriage 12 is moved from the second end point to the first end point of the movable range is detected. The inhibition area is estimated to be a main scanning direction area between a point on the linear scale 46 corresponding to the first count value when the speed abnormality is detected and a point on the linear scale 46 corresponding to the second count value when the speed abnormality is detected.

[0062] According to another example, the inhibition region may be estimated not in units of counts of the position counter, but in units of sections when the linear scale 46 is divided into a plurality of sections from one end to the other end. In this case, one or more sections including a region in the main scanning direction between the first count value and the second count value are estimated as the inhibition region.

[0063] According to yet another example, the width of the inhibition region in the main scanning direction may be estimated from the time from when the speed abnormality is detected until the speed abnormality is no longer detected and the target speed Vr. The start point and end point of the inhibition region may be estimated based on the count value of a position counter at the point where the speed abnormality begins to be detected and the width. In other words, the end point of the inhibition region may be estimated to be a point away from the start point in the main scanning direction by a distance corresponding to the width.

[0064] In other words, depending on whether the count value of the position counter when the carriage 12 is moved from one end to the other end differs from the design value, it may be determined whether the speed abnormality is caused by the adhesion of the dirt 70. Information on the inhibition area estimated in the prescan process is recorded in a register (not shown) of the ASIC 2, and shared by the CR motor control unit 32 and the linear encoder processing unit 34.

[0065] The recorded information on the inhibition area may include information on the start and end positions of the inhibition area when the carriage 12 moves in the forward direction and the start and end positions of the inhibition area when the carriage 12 moves in the backward direction. The register may record the start position and width of the inhibition area as the inhibition area information. The width of the inhibition area corresponds to the amount of change in the position counter from the point where the carriage 12 enters the inhibition area.

[0066] The estimation of the inhibition region may be performed by the linear encoder processing unit 34 in the ASIC 2, or may be performed by the processor 3 based on the first count value and the second count value obtained from the ASIC 2, etc.

[0067] After completing the pre-scan process (S110), the processor 3 determines whether or not there is an unprocessed print job (S120). The print job is received from an external device via the communication interface 7. If there is no unprocessed print job (No in S120), the processor 3 executes the process of S140.

[0068] When the processor 3 determines that an unprocessed print job exists (Yes in S120), it executes the print process shown in Fig. 5 as the print job (S130). By executing the print process, an image corresponding to the print job is formed on the paper P. The printed and processed paper P is output to a paper output tray (not shown) of the image forming system 1.

[0069] When the processor 3 ends the print process, it executes the process of S140. In S140, the processor 3 judges whether the end condition is satisfied. For example, the processor 3 judges that the end condition is satisfied when the power is shut down or when the processor 3 transitions to the sleep mode.

[0070] If it is determined that the termination condition is not satisfied (No in S140), the processor 3 returns the process to S120 and waits until an unprocessed print job occurs or the termination condition is satisfied. If it is determined that the termination condition is satisfied (Yes in S140), the main process shown in FIG. 4 is terminated.

[0071] When the processor 3 starts the printing process (see FIG. 5) in S130, it starts the paper feed process (S210). In the paper feed process, the processor 3 causes the LF motor control unit 33 to control the LF motor 21 so that a sheet of paper P is separated from a paper feed tray (not shown) and transported in the sub-scanning direction to a position where ink droplets are ejected by the recording head 11. The processor 3 further places the carriage 12, which is located at the home position, in the initial position through the control of the CR motor 13 by the CR motor control unit 32 (S220).

[0072] Thereafter, the processor 3 sets, in the CR motor control unit 32, a speed profile that defines a target speed Vr from the movement start point to the target stopping point of the carriage 12 (S230). The target speed Vr from the movement start point to the target stopping point corresponds to the target speed Vr until the carriage 12 moves from a turning point to the next turning point.

[0073] The speed profile is set in consideration of an ink ejection section in the movement path of the carriage 12 from the movement start point to the target stopping point, where the ink droplet ejection operation is performed by the recording head 11. The ink ejection section corresponds to a processing section in which the paper P is printed and processed by ejecting ink droplets.

[0074] The substance of the speed profile may be data representing the target speed Vr at each point from the start of movement to the stop as the target speed Vr from the start of movement to the target stop point. According to another example, the substance of the speed profile may be data representing the target speed Vr at each point from the start of movement to the target stop point.

[0075] Specifically, processor 3 sets the speed profile in the following procedure. Processor 3 identifies the ink discharge section, and judges whether the distance from the end point of the ink discharge section to the target stopping point is equal to or greater than a predetermined distance required for high-speed movement. If the distance is equal to or greater than the predetermined distance, a first type of speed profile shown in Fig. 6A that includes a high-speed section is set. If the distance is not equal to or greater than the predetermined distance, a second type of speed profile shown in Fig. 6B that does not include a high-speed section is set.

[0076] For either speed profile, a first speed Vr1 determined for forming a good quality image on the paper P is set as the target speed Vr for the ink ejection section, and the target speed Vr is defined so that the carriage 12 moves at a constant speed at the first speed Vr1 in the ink ejection section. In the first type of speed profile, the target speed Vr is defined so that the carriage 12 moves at a high speed at a second speed Vr2 higher than the first speed Vr1 in the non-ink ejection section.

[0077] Specifically, the first type of velocity profile shown in FIG. 6A has the following characteristics. The acceleration section includes an acceleration section in which the carriage 12 is accelerated from the movement start point to the first velocity Vr1. The end point of the acceleration section is before the start point of the ink ejection section. The period from when the carriage 12 finishes accelerating to the first velocity Vr1 until when the carriage 12 reaches the end point of the ink ejection period includes a constant velocity period (i.e., a first constant velocity period) in which the carriage 12 moves at a constant speed of the first velocity Vr1. The re-acceleration section includes a re-acceleration section in which the carriage 12 is accelerated to the second velocity Vr2 immediately after the carriage 12 passes the end point of the ink ejection section. From the point at which the acceleration of the carriage 12 to the second speed Vr2 ends until the carriage 12 reaches the deceleration start point that is the distance before the target stopping point required for deceleration, a high-speed section (i.e., a second constant speed section) is included in which the carriage 12 moves at a constant speed at the second speed Vr2. The deceleration section includes a deceleration section in which the carriage 12 decelerates and stops toward the target stopping point, starting immediately after the carriage 12 reaches the deceleration start point.

[0078] The second type of velocity profile shown in FIG. 6B has the following characteristics. The acceleration section includes an acceleration section in which the carriage 12 is accelerated from the movement start point to the first velocity Vr1. The end point of the acceleration section is before the start point of the ink ejection section. The period from the end of acceleration of the carriage 12 to the first speed Vr1 until the carriage 12 passes through the ink ejection section and reaches the deceleration start point that is the distance before the target stopping point that is required for deceleration, includes a constant speed section in which the carriage 12 moves at a constant speed of the first speed Vr1. The deceleration section includes a deceleration section in which the carriage 12 decelerates and stops toward the target stopping point, starting immediately after the carriage 12 reaches the deceleration start point.

[0079] After setting the speed profile in S230, the processor 3 executes printing in the main scanning direction (S240). In S240, the processor 3 instructs the CR motor control unit 32 to execute control of the CR motor 13 according to the speed profile set in S230. The processor 3 further inputs image data representing an image to be formed on the paper P to the recording control unit 31, and instructs the recording control unit 31 to control the ejection operation of ink droplets by the recording head 11 based on this image data.

[0080] In response to this command, the CR motor control unit 32 controls the CR motor 13 so that the carriage 12 moves from the movement start point to the next turning point corresponding to the target stopping point along a speed trajectory that follows the set speed profile. The recording control unit 31 controls the recording head 11 so that the recording head 11 ejects ink droplets for forming an image corresponding to the image data in accordance with the movement of the carriage 12.

[0081] By executing the main scanning direction printing in S240, an image for one pass based on the image data is formed on the paper P. The image for one pass here refers to an image formed on the paper P by the ink droplet ejection operation of the recording head 11 while the carriage 12 moves in the main scanning direction from one turning point to another.

[0082] When the main scanning direction printing in S240 is completed, the processor 3 determines whether the printing process for one page of the paper P is complete (S250). If it is determined that the printing process is not complete (No in S250), the processor 3 causes the LF motor control unit 33 to control the LF motor 21 so as to transport the paper P in the sub-scanning direction by a predetermined distance corresponding to the width of the image for one pass in the sub-scanning direction (S260).

[0083] After executing the process of S260, the processor 3 sets a speed profile to be used in the next main scanning direction printing (S230). After setting the speed profile, the processor 3 executes main scanning direction printing using the speed profile (S240), thereby forming an image for one pass on the paper P that has been sent a predetermined distance in the sub scanning direction by the immediately preceding process of S260.

[0084] Processor 3 repeatedly executes the processes of S230 to S260 until it determines that printing of one page of paper P is complete, and when it determines that printing of one page of paper P is complete (Yes in S250), it executes the process of S270.

[0085] In S270, the processor 3 executes a paper discharge process for the printed paper P. In the paper discharge process, the LF motor 21 is controlled via the ASIC 2 to discharge the printed paper P onto a paper discharge tray (not shown).

[0086] Processor 3 further determines whether the print job being processed has image data for the next page (S280), and if so (Yes in S280), returns to S210 and executes page printing processing for the next page (S210-S270). In this manner, processor 3 executes page printing processing for each page, and when page printing processing for all pages is completed (No in S280), ends the printing processing.

[0087] Next, the details of the motor control process executed by the CR motor control unit 32 for the speed control of the carriage 12 based on the speed profile will be described with reference to Fig. 7. Upon receiving a command from the processor 3 in S240, the CR motor control unit 32 executes the motor control process shown in Fig. 7 at every predetermined control period until the carriage 12 is moved to the turning point according to the set speed profile.

[0088] In the motor control process for each control cycle, the CR motor control unit 32 judges whether the carriage 12 is in a re-acceleration section (S310). Whether the carriage 12 is in a re-acceleration section is judged based on the elapsed time from the start of the speed control of the carriage 12 based on the speed profile. If the speed profile is a second type speed profile without a high speed section, the processor 3 formally judges that the carriage 12 is not in a re-acceleration section.

[0089] If it is determined that the carriage 12 is not in the re-acceleration section (No in S310), the CR motor control unit 32 determines whether the carriage 12 is located in the inhibition area (S320). Whether the carriage 12 has entered the inhibition area and is located in the inhibition area is determined based on the position measurement value X of the carriage 12 obtained from the linear encoder processing unit 34 and information on the inhibition area detected in the pre-scan process (S310).

[0090] If it is determined that the carriage 12 is not located within the inhibition area (No in S320), the CR motor control unit 32 calculates the deviation E = Vr - V between the speed measurement value V of the carriage 12 input from the linear encoder processing unit 34 and the target speed Vr according to the speed profile, and calculates the feedback control amount Ufb based on the deviation E (S340).

[0091] The CR motor control unit 32 inputs the deviation E to a predetermined transfer function to calculate a feedback operation amount Ufb for reducing the deviation E. The CR motor control unit 32 may calculate the feedback operation amount Ufb corresponding to the deviation E by a PID control method.

[0092] When it is determined that the carriage 12 is located within the inhibition area (Yes in S320), the CR motor control unit 32 corrects the speed measurement value V used to calculate the deviation E because the reliability of the speed measurement value V is low (S330). * is, for example, a moving average of the speed measurement value V. Then, the CR motor control unit 32 calculates the corrected speed measurement value V * Deviation E=Vr-V based on * The feedback manipulated variable Ufb is calculated from the above (S340).

[0093] The CR motor control unit 32 determines the calculated feedback operation amount Ufb as the operation amount U for the CR motor 13, and inputs a corresponding control signal to the CR motor driver 19 (S350). As a result, the CR motor driver 19 applies a drive power (specifically, a drive voltage) corresponding to the operation amount U to the CR motor 13 to drive the CR motor 13.

[0094] In this manner, when the carriage 12 is outside the re-acceleration section, the CR motor control unit 32 controls the speed of the carriage 12 by feedback control based on the deviation E between the speed measurement value V and the target speed Vr.

[0095] On the other hand, when the CR motor control unit 32 determines that the carriage 12 is in the re-acceleration zone (Yes in S310), it executes the zone control process shown in Fig. 8 (S400). When the zone control process starts, the CR motor control unit 32 determines whether the re-acceleration zone at least partially overlaps with the inhibition zone (S410). That is, the CR motor control unit 32 determines whether the inhibition zone is in the re-acceleration zone. When the inhibition zone is in zone R11 shown in Fig. 6A, the processor 3 makes a positive determination in S410.

[0096] If it is determined in S410 that there is an overlap (Yes in S410), the CR motor control unit 32 determines whether or not the carriage 12 is located within the inhibition area (S420). If the CR motor control unit 32 determines that the re-acceleration section does not overlap with the inhibition area (No in S410) or that the carriage 12 is not located within the inhibition area (No in S420), it calculates the feedback operation amount Ufb (S430) in the same manner as in the process in S340.

[0097] That is, the CR motor control unit 32 calculates the deviation E=Vr-V between the speed measurement value V of the carriage 12 input from the linear encoder processing unit 34 and the target speed Vr according to the speed profile, and calculates the feedback control amount Ufb based on the deviation E (S430).

[0098] The CR motor control unit 32 further inputs a control signal corresponding to the calculated feedback operation amount Ufb to the CR motor driver 19 (S440). As a result, the CR motor control unit 32 controls the speed of the carriage 12 by feedback control.

[0099] On the other hand, when the CR motor control unit 32 determines that the carriage 12 is located within the inhibition area in the re-acceleration section (Yes in S420), it calculates the feedforward manipulated variable Uff corresponding to the target speed Vr (S450) without using the speed measurement value V. The feedforward manipulated variable Uff is obtained by inputting the target speed Vr according to the speed profile into a transfer function based on the equation of motion of the carriage 12. The equation of motion of the carriage 12 can be expressed as follows.

[0100]

number

[0101] In order to realize the target speed Vr in the carriage 12, it is necessary to apply a force f obtained by substituting the target speed Vr for the variable v in the above equation of motion to the carriage 12 via the CR motor 13.

[0102] There is a proportional relationship between the drive voltage e of the CR motor 13 and the force f acting on the carriage 12 by the drive voltage e, and when force f is required, the drive voltage e of the CR motor 13 can be determined according to the conversion formula e=f / K, where K is a conversion coefficient.

[0103] As described above, the operation amount U for the CR motor 13 is a voltage command value that specifies the drive voltage e. The CR motor control unit 32 converts the force f obtained by substituting the target speed Vr of the speed profile into the above equation of motion into the drive voltage e, and can calculate the feedforward operation amount Uff as the corresponding voltage command value.

[0104] The CR motor control unit 32 determines the feedforward operation amount Uff calculated in this manner as the operation amount U for the CR motor 13 (S450). After that, the CR motor control unit 32 inputs a control signal corresponding to the determined operation amount U to the CR motor driver 19 (S460). As a result, the CR motor control unit 32 applies a drive power (specifically, a drive voltage) corresponding to the determined operation amount U to the CR motor 13 to drive the CR motor 13.

[0105] By executing the section control process in this manner, the CR motor control unit 32 calculates the feedback operation amount Ufb or the feedforward operation amount Uff as the operation amount U for the CR motor 13 in the re-acceleration section, and controls the CR motor 13.

[0106] Specifically, the CR motor control unit 32 performs feedforward control based on the speed profile only when the carriage 12 is located within the inhibition area in the re-acceleration section, and performs feedback control based on the speed profile in other cases. The CR motor control unit 32 switches the control of the CR motor 13 based on the feedforward control method to the control based on the feedback control method on the condition that the carriage 12 has passed through the inhibition area.

[0107] As another example, the CR motor control unit 32 may operate so as not to execute the process of S420. In this case, when the re-acceleration section and the inhibition area at least partially overlap (Yes in S410), the CR motor control unit 32 executes the processes of S450 and S460 for each control cycle from when the carriage 12 enters the re-acceleration section to when it passes through the re-acceleration section, regardless of whether the carriage 12 is located in the inhibition area or not, thereby feedforward controlling the speed of the carriage 12 throughout the entire re-acceleration section.

[0108] As yet another example, in the section control processing (S400), the CR motor control unit 32 does not execute the processes of S410 and S420, but executes the processes of S450 and S460, thereby enabling feedforward control of the speed of the carriage 12 throughout the entire re-acceleration section, regardless of whether the re-acceleration section overlaps with the inhibition area.

[0109] In addition, in order to suppress the influence of measurement errors occurring in the inhibition area, the linear encoder processing unit 34 can repeatedly execute a correction process shown in Fig. 9 in addition to the process of calculating the measurement values ​​of the position and speed of the carriage 12 based on the encoder signal. The correction process is performed to remove errors contained in the position measurement value X of the carriage 12, which is measured as the count value of the position counter when passing through the inhibition area.

[0110] When the correction process is started, the linear encoder processing unit 34 waits until the carriage 12 passes through the inhibition area (S510). The passage here means that the carriage 12 passes through the end point of the inhibition area so as to leave the inhibition area.

[0111] In S510, the linear encoder processing unit 34 can determine that the carriage 12 has entered the inhibition area based on the position measurement value X of the carriage 12. The linear encoder processing unit 34 can determine whether or not the carriage 12 has passed through the inhibition area based on the position measurement value X of the carriage 12 when the carriage 12 enters the inhibition area, the width of the inhibition area, and the movement distance of the carriage 12 after entering the inhibition area. The movement distance can be calculated based on a speed profile, and specifically, can be calculated as a time integral of the target speed Vr based on the target speed Vr of the carriage 12 and the elapsed time after entering the inhibition area.

[0112] When the linear encoder processing unit 34 determines that the carriage 12 has passed through the inhibition area (Yes in S510), it corrects the error in the count value of the position counter that has occurred in the inhibition area (S520).

[0113] For example, the linear encoder processor 34 can calculate the difference (D1-D2) between the travel distance D1 (converted into a count value) of the carriage 12 calculated as the time integral of the target speed Vr from the point in time when the carriage 12 enters the inhibition area and the deviation D2 of the count value of the position counter from the point in time when the carriage 12 is determined to have passed through the inhibition area, as the count value error caused by the stain 70. The linear encoder processor 34 can correct the count value by adding the difference (D1-D2) so that the deviation D2 matches the travel distance D1.

[0114] According to another example, the linear encoder processing unit 34 determines an error in the count value of the position counter that occurs in the inhibition region during prescanning, and corrects the count value by the determined error, thereby correcting the error.

[0115] According to the image forming system 1 of this embodiment described above, when forming an image on paper P, the CR motor control unit 32 reciprocates the carriage 12 in accordance with the speed profile, but in the non-ink ejection section, the speed of the carriage 12 is controlled so that the carriage 12 moves at high speed.

[0116] To prepare for the possibility that speed measurement may be temporarily impossible due to dirt 70 on the linear scale 46, the CR motor control unit 32 suppresses unstable control caused by measurement errors by controlling the CR motor 13 using a feedforward control method in the re-acceleration section involving acceleration at high speeds.

[0117] When dirt 70 is attached to the linear scale 46, the edge interval is usually longer, and a measurement error occurs in the direction in which the speed measurement value V becomes smaller relative to the actual speed. Therefore, if the acceleration control of the carriage 12 is performed by feedback control in the inhibition region, the carriage 12 may accelerate excessively. In the high speed range, even if the measurement error occurs for a short period of time, it has a large effect on the speed of the carriage 12.

[0118] When the carriage 12 accelerates at high speeds, even if feedback control is performed by correcting the speed measurement value V, the correction may not work sufficiently to suppress the control error. In order to cancel the control error caused by excessive acceleration, excessive deceleration is required, which tends to increase the load acting on the CR motor 13 and the driving noise and vibration from the CR motor 13.

[0119] By performing feedforward control in the re-acceleration section as in this embodiment, it is possible to suppress excessive acceleration and achieve more stable control than feedback control. Therefore, according to this embodiment, in the image forming system 1 in which the carriage 12 is moved at high speed in the non-ink ejection section, the carriage 12 can be moved at an appropriate high speed.

[0120] [First modified example] Next, a first modified image forming system 1 will be described. The first modified image forming system 1 is the same as the above-described embodiment except that the motor control process executed by the CR motor control unit 32 is partially different from that of the above-described embodiment.

[0121] In the first modified example, the CR motor control unit 32 repeatedly executes the motor control process shown in Fig. 10 for each control period, instead of the motor control process shown in Fig. 7. In the following, the motor control process of the first modified example executed by the CR motor control unit 32 will be selectively described in terms of parts different from the above embodiment, and descriptions of other parts having the same configuration as the above embodiment will be omitted. The processes with the same step numbers in Fig. 10 may be understood to be the same as the processes with the same step numbers in the motor control process shown in Fig. 7.

[0122] When the motor control process shown in Fig. 10 is started, the CR motor control unit 32 judges whether the carriage 12 is in the re-acceleration zone (S310). If it is judged that the carriage 12 is in the re-acceleration zone (Yes in S310), the CR motor control unit 32 executes the zone control process (see Fig. 8) in S400. Then, the motor control process ends.

[0123] If it is determined that the carriage 12 is not in the re-acceleration section (No in S310), the CR motor control unit 32 determines whether the carriage 12 is in the acceleration section (S311). The CR motor control unit 32 can determine whether the carriage 12 is in the acceleration section based on the elapsed time from the start of the speed control based on the speed profile.

[0124] If it is determined that the carriage 12 is within the acceleration section (Yes in S311), the CR motor control unit 32 determines whether the interval from the end point of the acceleration section to the start point of the ink ejection section is equal to or greater than a reference distance (S315). The reference distance is set in advance, taking into consideration the distance required for the speed of the carriage 12 to stabilize at a constant speed after constant speed control for the carriage 12 is started. If it is determined that the interval is equal to or greater than the reference distance (Yes in S315), the CR motor control unit 32 executes the process of S360.

[0125] If it is determined that the carriage 12 is not within the acceleration section (No in S311) or that the distance from the end point of the acceleration section to the start point of the ink ejection section is less than the reference distance (No in S315), the CR motor control unit 32 executes the processes of S320-S350, similar to the motor control process shown in FIG. 7.

[0126] That is, the CR motor control unit 32 feedback-controls the speed of the carriage 12 in accordance with the speed profile. When the carriage 12 is located within the inhibition area, the speed measurement value V of the carriage 12 is corrected (S330), and feedback control is executed based on the corrected speed measurement value V (S340, S350).

[0127] In S360, the CR motor control unit 32 judges whether the carriage 12 in the acceleration section is located in the inhibition area. If it is judged that the carriage 12 is not located in the inhibition area (No in S360), the CR motor control unit 32 executes the processes of S340 and S350 to feedback control the speed of the carriage 12.

[0128] In S360, when it is determined that the carriage 12 is located within the inhibition area (Yes in S360), the CR motor control unit 32 calculates the feedforward operation amount Uff in the same manner as in the process of S450 (S370). The CR motor control unit 32 determines the feedforward operation amount Uff calculated in this manner as the operation amount U for the CR motor 13, and inputs a corresponding control signal to the CR motor driver 19 (S380). As a result, the CR motor control unit 32 performs feedforward control of the speed of the carriage 12.

[0129] According to the first modification, the CR motor control unit 32 controls the CR motor 13 so as to perform feedforward control not only in the re-acceleration section but also in the acceleration section. This makes it possible to suppress a speed measurement error caused by dirt 70 on the linear encoder 14 during acceleration, which in turn makes the speed control of the carriage 12 unstable.

[0130] According to the first modification, feedforward control is performed in the acceleration section only when the interval between the end point of the acceleration section and the start point of the ink ejection section is sufficiently large, because if the interval is short, control errors caused by switching from feedforward control to feedback control may have an undesirable effect on the stability of speed control in the ink ejection section.

[0131] Thus, according to the first variant, the CR motor control unit 32 switches between feedforward control and feedback control depending on the situation of the carriage 12, so that the speed control of the carriage 12 can be appropriately performed even in an environment where measurement errors occur.

[0132] According to another example, the CR motor control unit 32 may determine in S315 whether the distance from the end point of the inhibition area in the acceleration section to the start point of the ink ejection section is equal to or greater than a reference distance. This determination method also makes it possible to appropriately switch between feedforward control and feedback control in the acceleration section.

[0133] [Second modified example] Next, a second modified image forming system 1 will be described. However, the second modified image forming system 1 is different from the above-mentioned embodiment only in the motor control process executed by the CR motor control unit 32, and the other configurations are the same as those of the above-mentioned embodiment.

[0134] In the second modified example, the CR motor control unit 32 repeatedly executes the motor control process shown in Fig. 11 for each control period, instead of the motor control process shown in Fig. 7. In the following, the motor control process of the second modified example executed by the CR motor control unit 32 will be selectively described in terms of parts different from the above embodiment, and descriptions of other parts having the same configuration as the above embodiment will be omitted.

[0135] 11 starts, the CR motor control unit 32 judges whether the CR motor 13 is under feedforward control (S300). The CR motor control unit 32 judges positively if the CR motor 13 is being controlled by calculating the feedforward operation amount Uff in the previous control cycle, and judges negatively otherwise. If the judgement is positive here, it means that the carriage 12 was located in the inhibition area in the re-acceleration section in the previous control cycle.

[0136] When the CR motor control unit 32 determines that feedforward control is not in progress (No in S300), it executes the processes from S310 onward shown in Fig. 7, as in the above-described embodiment. When the CR motor control unit 32 determines that feedforward control is in progress (Yes in S300), it determines whether the carriage 12 has passed through the inhibition area (S301). The carriage 12 having passed through the inhibition area corresponds to the carriage 12 moving out of the inhibition area from the inside to the outside.

[0137] When it is determined that the carriage 12 has passed through the inhibition area (Yes in S301), the CR motor control unit 32 executes the process of S310 and subsequent steps shown in Fig. 7. On the other hand, when it is determined that the carriage 12 is located within the inhibition area and has not passed through the inhibition area (No in S301), the CR motor control unit 32 calculates the feedforward operation amount Uff (S303), similar to the process in S450. The CR motor control unit 32 determines the calculated feedforward operation amount Uff as the operation amount U for the CR motor 13, and inputs a corresponding control signal to the CR motor driver 19 (S305).

[0138] In other words, when the carriage 12 enters the inhibition area during the re-acceleration section, the CR motor control unit 32 continues feedforward control until the carriage 12 passes through the inhibition area, even after the carriage 12 has passed the re-acceleration section, and after the carriage 12 has passed the inhibition area, switches the speed control of the carriage 12 to feedback control.

[0139] According to the second modified example, as described above, once the CR motor control unit 32 starts feedforward control, the feedforward control is continued until the carriage 12 leaves the inhibition area. When the inhibition area continues from the re-acceleration area to the high-speed area adjacent to the re-acceleration area, the CR motor control unit 32 continues the feedforward control until the carriage 12 leaves the inhibition area even if the carriage 12 is located in the high-speed area.

[0140] Therefore, according to the second modified example, when the measurement error is large before the carriage 12 leaves the inhibition zone, it is possible to more appropriately control the speed of the carriage 12 than when the speed control of the carriage 12 is switched from feedforward control to feedback control only on the condition that the carriage 12 has left the re-acceleration zone. According to the main embodiment described above, even if the inhibition zone continues from the re-acceleration zone to the high-speed zone adjacent to the re-acceleration zone, the CR motor control unit 32 switches the speed control of the carriage 12 from feedforward control to feedback control on the condition that the carriage 12 has left the re-acceleration zone.

[0141] [Third Modification] Next, a third modified image forming system 1 will be described. The third modified image forming system 1 is the same as the above-mentioned embodiment except that the process executed by the processor 3 is partially different from that of the above-mentioned embodiment. Therefore, hereinafter, the process executed by the processor 3 that is different from that of the above-mentioned embodiment will be selectively described, and the description of the other parts that are the same as those of the above-mentioned embodiment will be omitted.

[0142] In the third modified example, in S230 of the print process (see FIG. 5), the processor 3 executes a speed profile setting process shown in FIG. 12. In this speed profile setting process, the processor 3 first generates a standard speed profile (S610). Here, the processor 3 executes a standard speed profile generation process shown in FIG. 13.

[0143] The standard speed profile is a speed profile that defines the target speed of the carriage 12 when the carriage 12 moves from the movement start point to the target stop point in the next main scanning direction printing (S240) without taking into account the presence or absence of an obstruction area. This standard speed profile is modified depending on the presence of an obstruction area, as described below.

[0144] When the standard speed profile generation process starts, the processor 3 determines the ink ejection section in the movement path from the start point of the carriage 12 to the target stopping point in the next main scanning direction printing, where the recording head 11 performs the ink droplet ejection operation (S611).

[0145] Then, the processor 3 determines whether the distance from the end point of the ink discharge section to the target stop point is equal to or greater than a predetermined distance required for high-speed movement (S612). If the determination in S612 is affirmative (Yes in S612), the processor 3 determines in S613 whether the distance from the movement start point to the start point of the ink discharge section is equal to or greater than a predetermined distance required for high-speed movement.

[0146] If the processor 3 makes a negative decision in S613 (No in S613), it generates a first standard speed profile having the same shape as the speed profile shown in Fig. 6A as the standard speed profile (S614). After that, it ends the standard speed profile generation process shown in Fig. 13.

[0147] On the other hand, if the processor 3 determines in S613 that the distance from the movement start point to the start point of the ink ejection section is equal to or greater than the predetermined distance required for high-speed movement (Yes in S613), it generates a second standard speed profile having the characteristics shown in Fig. 14A as the standard speed profile (S615). Thereafter, the standard speed profile generation process shown in Fig. 13 ends.

[0148] Specifically, the second standard speed profile has the following characteristics. Includes an acceleration section in which the carriage 12 accelerates from the movement start point to the second velocity Vr2. A first high-speed section is included in which the carriage 12 moves at a constant speed at the second speed Vr2 from the end of the acceleration of the carriage 12 to the second speed to a first deceleration start point before the start of the ink ejection section. The first deceleration start point is a point before the start of the ink ejection section by a distance that is predetermined so that the carriage 12 can stably run at the first speed Vr1 at the start of the ink ejection section. Includes an intermediate deceleration section in which the carriage 12 is decelerated from the first deceleration start point to the first speed Vr1. The period from when the carriage 12 finishes decelerating to the first velocity Vr1 until the carriage 12 reaches the end point of the ink ejection period includes a constant velocity period in which the carriage 12 moves at a constant velocity of the first velocity Vr1. The re-acceleration section includes a re-acceleration section in which the carriage 12 is accelerated to the second velocity Vr2 immediately after the carriage 12 passes the end point of the ink ejection section. A second high-speed section in which the carriage 12 moves at a constant speed at the second speed Vr2 is included from the point at which the acceleration of the carriage 12 to the second speed Vr2 ends until the carriage 12 reaches the deceleration start point that is the distance before the target stopping point that is required for deceleration. The deceleration section includes a deceleration section in which the carriage 12 decelerates and stops toward the target stopping point, starting immediately after the carriage 12 reaches the deceleration start point.

[0149] In addition, if processor 3 determines that the distance from the end point of the ink discharge section to the target stop point is less than the predetermined distance required for high-speed movement (No in S612), it executes the process of S617. In S617, processor 3 determines whether the distance from the movement start point to the start point of the ink discharge section is equal to or greater than the predetermined distance required for high-speed movement, similar to the process of S613.

[0150] If the processor 3 determines affirmatively in S617 (Yes in S617), it generates a third standard speed profile having the characteristics shown in Fig. 14B as the standard speed profile (S618). After that, it ends the standard speed profile generation process shown in Fig. 13.

[0151] Specifically, the third standard speed profile has the following characteristics: Includes an acceleration section in which the carriage 12 accelerates from the movement start point to the second velocity Vr2. A high-speed section is included in which the carriage 12 moves at a constant speed at the second speed Vr2 from the end of the acceleration of the carriage 12 to the second speed to a first deceleration start point before the start of the ink ejection section. The first deceleration start point is a point before the start of the ink ejection section by a distance that is predetermined so that the carriage 12 can stably run at the first speed Vr1 at the start of the ink ejection section. Includes an intermediate deceleration section in which the carriage 12 is decelerated from the first deceleration start point to the first speed Vr1. The period from the end of deceleration to the first speed Vr1 until the carriage 12 reaches the deceleration start point that is the distance before the target stopping point that is required for deceleration, includes a constant speed section in which the carriage 12 moves at a constant speed of the first speed Vr1. The deceleration section includes a deceleration section in which the carriage 12 decelerates and stops toward the target stopping point, starting immediately after the carriage 12 reaches the deceleration start point.

[0152] In addition, if the processor 3 makes a negative decision in S617 (No in S617), it generates a fourth standard speed profile having the same shape as the speed profile shown in Fig. 6B as the standard speed profile (S619). After that, the standard speed profile generation process shown in Fig. 13 is terminated.

[0153] After generating the standard speed profile in S610 (see FIG. 12), the processor 3 determines whether there is a stain 70 on the linear scale 46, i.e., whether there is an inhibiting area (S620). If the processor 3 determines that there is no inhibiting area (No in S620), it sets the standard speed profile generated in S610 as the speed profile to be used in the next main scanning direction printing (S660). Thereafter, the speed profile setting process ends.

[0154] When the processor 3 determines that there is an inhibition area (Yes in S620), it determines whether the inhibition area exists in an intermediate deceleration section in which the carriage 12 decelerates from the second speed Vr2 to the first speed Vr1.

[0155] If main scanning direction printing (S240) is performed based on the standard speed profile generated in S610, and the carriage 12 is positioned within the inhibition area, the processor 3 makes a positive judgment in S630 if the carriage 12 is to be speed controlled at a target speed corresponding to the intermediate deceleration section.

[0156] For example, when the standard speed profile generated in S610 is the second standard speed profile shown in FIG. 14A and the inhibition region is in the region R21 shown in FIG. 14A, the processor 3 makes an affirmative determination in S630.

[0157] For example, if the standard speed profile generated in S610 is the third standard speed profile shown in FIG. 14B and the inhibition region is in the region R31 shown in FIG. 14B, the processor 3 makes an affirmative determination in S630.

[0158] If it is determined that the inhibition region exists in the intermediate deceleration section (Yes in S630), the processor 3 executes the process of S640. If it is determined that the inhibition region does not exist in the intermediate deceleration section (No in S630), the processor 3 executes the process of S660.

[0159] In S640, the processor 3 modifies the standard speed profile generated in S610 so as to extend the constant speed section in the standard speed profile to the end point of the inhibition region and set the inhibition region as the constant speed section.

[0160] When the standard speed profile generated in S610 is the second standard speed profile shown in Fig. 14A, the processor 3 extends the constant speed section so as to advance the start point of the constant speed section to a point before entering the inhibition region R21, as shown in Fig. 15A. The dashed dotted line shown in Fig. 15A indicates the standard speed profile before correction, and the solid line indicates the speed profile after correction by extending the constant speed section.

[0161] When the standard speed profile generated in S610 is the third standard speed profile shown in Fig. 14B, the processor 3 extends the constant speed section so as to advance the start point of the constant speed section to a point before entering the inhibition region R31, as shown in Fig. 16. The dashed dotted line shown in Fig. 16 indicates the standard speed profile before correction, as in Fig. 15A, and the solid line indicates the speed profile after correction by extending the constant speed section.

[0162] As a result, the processor 3 corrects the standard speed profile so that the carriage 12 moves at a constant speed of the first speed Vr1 in a section including an inhibition region of an adjacent non-ink ejection section preceding an ink ejection section.

[0163] In the next S650, the processor 3 sets the speed profile corrected in the process of S640 as the speed profile to be used in the next main scanning direction printing, and then ends the speed profile setting process (S230).

[0164] As another example, in S640, the processor 3 may modify the standard speed profile generated in S610 so as to delete the high speed section upstream of the constant speed section.

[0165] For example, if the standard speed profile generated in S610 is the second standard speed profile shown in FIG. 14A, as shown in FIG. 15B, processor 3 may modify the standard speed profile generated above by deleting the first high-speed section from the standard speed profile and replacing the non-ink ejection section preceding the ink ejection section with a constant speed section at the first speed Vr1.

[0166] When the intermediate deceleration section includes an inhibition region, even if feedforward control is executed in the inhibition region, there is a possibility that the speed of the carriage 12 will not stabilize by the time the carriage 12 enters the ink ejection section.

[0167] According to this modified example, even if the standard speed profile includes an inhibition area in the intermediate deceleration section, the speed profile is modified so that the inhibition area is included in the constant speed section, thereby suppressing the influence of the inhibition area and enabling the speed of the carriage 12 to be controlled with high precision.

[0168] Therefore, according to this modification, it is possible to improve the throughput of the printing process by moving the carriage 12 at high speed while suppressing the influence of control errors due to the inhibition area.

[0169] Although the exemplary embodiments of the present disclosure, including modified examples, have been described above, it goes without saying that the present disclosure is not limited to the above-described embodiments and can take various forms. The technology of the present disclosure can be applied to various systems that realize the movement of a processing head that performs a predetermined processing on an object by motor control using an encoder, not limited to the image forming system 1 that forms an image on a paper P.

[0170] For example, the technology disclosed herein is applicable not only to inkjet printers but also to other serial printers and garment printers. The technology disclosed herein can also be applied to machine tools such as machines that print wiring patterns. The technology disclosed herein is not limited to systems that process objects, but can be applied to various systems that transport moving objects by controlling a motor using an encoder.

[0171] As an encoder for measuring the position and speed, an encoder other than the above-mentioned transmission-type linear encoder 14 may be used. For example, a reflection-type linear encoder may be used that receives light from a light-emitting element reflected by an encoder scale and reads the encoder scale.

[0172] When an encoder is used in which an optical sensor reads the encoder scale from an angle, such as a reflective linear encoder, the "inhibition area" may be the range of movement of the optical sensor when it moves over an area shifted from the front by a distance depending on the reading angle, rather than directly in front of the dirty area on the encoder scale.

[0173] The technology disclosed herein can also be applied to a control system using a rotary encoder. Known types of encoders include an encoder in which the sensor moves relative to a fixed encoder scale, causing the sensor to move relative to the encoder scale, and an encoder in which the encoder scale moves relative to a fixed sensor, causing the sensor to move relative to the encoder scale. The technology disclosed herein can be applied to a control system using either of these encoders.

[0174] The functions of one component in the above embodiment may be distributed among multiple components. The functions of multiple components may be integrated into one component. For example, the controller may not be configured with the processor 3 and the ASIC 2, but may be configured with one or more processors without an ASIC, may be configured with one or more ASICs without a processor, or may be configured with a combination of one or more processors and one or more ASICs. One or more components of the controller including at least one of a processor and an ASIC can cooperate with each other to execute the processing related to the controller of the present disclosure.

[0175] In addition, some of the configurations of the embodiments may be omitted. All aspects included in the technical ideas specified by the wording of the claims are embodiments of the present disclosure. [Explanation of symbols]

[0176] 1...image forming system, 2...ASIC, 3...processor, 4...ROM, 5...RAM, 6...EEPROM, 7...communication interface, 8...user interface, 9...bus, 11...recording head, 12...carriage, 13...CR motor, 14...linear encoder, 15...printing mechanism, 18...head driver, 19...CR motor driver, 21...LF motor, 22...rotary encoder, 29...LF motor driver, 31...recording control unit, 32...CR motor control unit, 33...LF motor control unit, 34...linear encoder processing unit, 35...rotary encoder processing unit, 41...guide shaft, 42...endless belt, 43...driving pulley, 44...driven pulley, 46...linear scale, 47...optical sensor, 48...slit, 50...light emitting unit, 51,52...light emitting element, 60...light receiving unit, 61,62...light receiving element, P...paper.

Claims

1. A motor; a moving body configured to be driven by the motor to move along a passage and process an object during the movement; A measuring device configured to measure the speed of the moving object; a controller configured to control the motor based on the speed measured by the measuring device in a feedback control manner so that the moving body moves from a movement start point on the path to a target stopping point at a speed that follows a speed profile; and Equipped with the speed profile defines an acceleration section in which the moving body transitions from the movement start point to a constant speed state, a deceleration section in which the moving body transitions from the constant speed state to a stop at the target stop point, and a target speed in an intermediate section between the acceleration section and the deceleration section; the intermediate section includes a first constant speed section in which the moving body moves at a first constant speed, a second constant speed section in which the moving body moves at a second constant speed higher than the first speed, and a non-constant speed section in which the moving body moves at a non-constant speed, the movable body operates to process the object in the first constant speed section; The controller controls the speed of the moving body by controlling the motor using a feedforward control method instead of the feedback control method in a re-acceleration period, which is the non-constant speed period and in which the moving body accelerates from the first speed to the second speed after passing through the first constant speed period.

2. An encoder comprising: an encoder scale; and a sensor configured to move relative to the encoder scale in conjunction with the movable body and to output an encoder signal based on reading of the encoder scale. Equipped with The measuring instrument measures the speed based on the encoder signal, The controller: determining whether or not a portion of the encoder scale to which an obstruction that obstructs normal reading of the encoder scale by the sensor is attached is within the re-acceleration section of an obstruction area, which is a movement area of ​​the movable body read by the sensor; The control system of claim 1, wherein if it is determined that the inhibition area is in the re-acceleration section, the motor is controlled in the re-acceleration section using the feedforward control method, and if it is determined that the inhibition area is not in the re-acceleration section, the motor is controlled in the re-acceleration section using the feedback control method.

3. 3. The control system according to claim 2, wherein the controller controls the motor using the feedforward control method in the re-acceleration section only in the section corresponding to the inhibition area, and controls the motor using the feedback control method outside the section corresponding to the inhibition area.

4. The control system according to claim 2 or claim 3, wherein the controller switches from controlling the motor using the feedforward control method that has been started to controlling the motor using the feedback control method on the condition that it is determined that the moving body has passed through the inhibition area.

5. A control system as described in any one of claims 2 to 4, wherein, when the inhibition area determined to be in the re-acceleration section continues to the second constant speed section adjacent to the re-acceleration section, the controller continues the control of the motor using the feedforward control method that has been started even after the moving body has passed through the re-acceleration section, and switches to control of the motor using the feedback control method on the condition that it is determined that the moving body has passed through the inhibition area.

6. A control system as described in any one of claims 2 to 4, wherein, when the inhibition area determined to be in the re-acceleration section continues to the second constant speed section adjacent to the re-acceleration section, the controller continues to control the motor using the feedforward control method that has been started until the moving body has passed the re-acceleration section, and, on the condition that the moving body has passed the re-acceleration section, switches to control of the motor using the feedback control method, thereby controlling the motor using the feedback control method in the inhibition area in the second constant speed section.

7. the second constant speed section is located before and after the first constant speed section in the intermediate section, the controller determines the presence or absence of the inhibition area in the non-constant speed section, within an intermediate deceleration section in which the moving body decelerates from the second speed to the first speed after passing through the second constant speed section located before the first constant speed section; A control system as described in any one of claims 2 to 6, wherein when it is determined that the inhibition area is in the intermediate deceleration section, the speed profile is corrected so that the first constant speed section is extended to a point before the moving body enters the inhibition area, and the motor is controlled in the inhibition area using the feedback control method in accordance with the corrected speed profile.

8. The control system according to any one of claims 2 to 7, wherein when the controller controls the motor using the feedback control method in the inhibition region, the controller corrects the speed measured by the measuring instrument and controls the motor based on the corrected speed.

9. a processing section in which the movable body processes the object is included in a part of the first constant speed section, The controller: Determining the presence or absence of the inhibition region within the acceleration section, and determining the distance between the end point of the inhibition region and the start point of the processing section, or the distance between the start point of the intermediate section and the start point of the processing section; A control system as described in any one of claims 2 to 8, wherein when the inhibition area is within the acceleration section and the distance is equal to or greater than a reference value, the speed of the moving body is controlled by controlling the motor in the acceleration section using the feedforward control method instead of the feedback control method.

10. The measuring instrument measures a position of the moving object based on the encoder signal, The controller: A control system as described in any one of claims 2 to 9, which determines that the moving body is entering the inhibition area based on the position of the moving body measured by the measuring instrument, and further determines that the moving body has passed through the inhibition area based on the speed profile.

11. The control system according to any one of claims 1 to 10, wherein the feedforward control method is a method for determining an operation amount for the motor based on the speed profile without using the speed measured by the measuring instrument, and controlling the motor with the determined operation amount.

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