control system

Abstract

To make it possible to calculate a movement distance of a movable body with high accuracy while suppressing cost increase.SOLUTION: A controller acquires first rotation amount information and second rotation amount information while moving a movable body by a motor. The first and second rotation amount information corresponds to motor rotation amount information from a rotation amount information output part when first and second detected parts are respectively detected by a single detection part mounted on the movable body. The controller calculates a correction value on the basis of the first and second rotation amount information and a design distance between the first and second detected parts. The correction value indicates actual movement distance of the movable body per a prescribed motor rotation amount. The controller calculates the movement distance of the movable body by use of the rotation amount information and the correction value, and controls prescribed action of the movable body on the basis of the calculated movement distance.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a technology for controlling movement of a moving body. [Background Art]

[0002] Patent Document 1 discloses an inkjet recording apparatus configured to detect the position of a carriage using a rotary encoder. This inkjet recording apparatus is provided with sensors for detecting the carriage at both ends of the movement range of the carriage, respectively. The inkjet recording apparatus calculates a correction value based on the actual number of pulses (i.e., the count value) from the rotary encoder when the carriage moves between the two sensors, and the designed distance or designed count value between the two sensors. The correction value is used for calculating the movement distance of the carriage. [Prior Art Document] [Patent Document]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-179503 [Summary of the Invention] [Problem to be Solved by the Invention]

[0004] The above-described inkjet recording apparatus requires two sensors to calculate the correction value, which consequently increases the cost of the inkjet recording apparatus. Furthermore, in the above-described inkjet recording apparatus, since the two sensors are provided at both ends of the movement range of the carriage, a problem may occur in that the count value detected between the two sensors deviates from the count value corresponding to the actual distance between the two sensors. Specifically, for example, when the apparatus is configured such that the sensor detects the carriage when the carriage stops at the end of the movement range, the above problem may occur due to mechanical factors when the carriage stops (for example, elongation of a belt, vibration, etc.).

[0005] One aspect of this disclosure is the desire to provide a technology that can calculate the travel distance of a moving object with high accuracy while keeping costs down. [Means for solving the problem]

[0006] A control system in one aspect of this disclosure comprises a motor, a moving body, a single detection unit, a rotation amount information output unit, and a controller. The moving body is moved along a predetermined direction by a motor. The moving body processes an object by performing predetermined operations during its movement. The detection unit is mounted on the moving body. In other words, the detection unit detects the first and second detected parts while the moving body is moving. The first and second detected parts are separated from each other along the direction of movement and are detected by the detection unit while the moving body is moving along that direction. The rotation amount information output unit outputs rotation amount information indicating the amount of rotation of the motor.

[0007] The controller performs the following processes: movement processing, rotation amount information acquisition processing, correction value calculation processing, and movement distance calculation processing. The movement process moves the moving body along the direction of movement using a motor. The rotation amount information acquisition process acquires first rotation amount information and second rotation amount information. The first rotation amount information is the rotation amount information from the rotation amount information output unit when the first detected part is detected by the detection unit while the moving body is moving due to the movement process. The second rotation amount information is the rotation amount information from the rotation amount information output unit when the second detected part is detected by the detection unit while the moving body is moving due to the movement process. The correction value calculation process calculates a correction value based on the first and second rotation amount information acquired by the rotation amount information acquisition process and theoretical distance information. The theoretical distance information is information indicating the design distance between the first detected part and the second detected part. The correction value directly or indirectly indicates the actual distance traveled by the moving body per predetermined amount of motor rotation. The travel distance calculation process calculates the travel distance of the moving body using the rotation amount information from the rotation amount information output unit and the correction value calculated by the correction value calculation process. The mobile object control process controls a predetermined action by the mobile object based on the distance traveled calculated by the distance traveled calculation process.

[0008] In this type of control system, the first and second detectable units are detected while the moving object is in motion. Moreover, the first and second detectable units are detected by a single detection unit mounted on the moving object. Therefore, it is possible to calculate the movement distance of the moving object with high accuracy while keeping costs down.

[0009] The rotation amount information output unit may also have a rotary encoder. The rotary encoder outputs a signal each time the motor rotates by a certain angle in a predetermined rotational direction. The rotation amount information output unit may output rotation amount information based on the signal from the rotary encoder.

[0010] Furthermore, the controller may also perform control processing based on the distance traveled calculated by the distance traveled calculation process. The control processing may include, for example, controlling a predetermined action by the moving object.

[0011] Furthermore, the distance calculation process may also calculate the position of the moving object relative to or starting from a specified position, based on the distance traveled from that specified position. In this case, the controller may control the predetermined movement of the moving object based on the calculated position of the moving object during the control process.

[0012] Furthermore, the term "single detection unit" as described above may mean that the moving object is equipped with only one detection unit. Alternatively, the term "single detection unit" as described above may mean that although the moving object is equipped with multiple detection units, the calculation of the correction value uses first and second rotation amount information based on the detection result of only one of those multiple detection units. [Brief explanation of the drawing]

[0013] [Figure 1] This is a block diagram showing the configuration of the image forming system according to the embodiment. [Figure 2] This is an explanatory diagram showing the configuration of the carriage transport mechanism and the paper transport mechanism. [Figure 3]This is an explanatory diagram illustrating the relationship between the count value based on the signal from the encoder and the carriage position, as well as the correction calculation. [Figure 4] This is a flowchart of the print control process. [Figure 5] This is an explanatory diagram showing other implementation examples of the first and second detected units. [Modes for carrying out the invention]

[0014] Hereinafter, exemplary embodiments of the present disclosure will be described with reference to the drawings. [1. Embodiments] (1) Configuration of the image forming system The image forming system 1 of this embodiment, shown in Figure 1, is configured as an inkjet printer. The image forming system 1 includes a main controller 10, a communication interface 15, a print controller 20, and a transport controller 40.

[0015] The main controller 10 comprises a CPU 11 and a storage unit 12. The storage unit 12 is capable of storing various programs and data. The storage unit 12 includes, for example, ROM and RAM. The ROM stores various programs. The CPU 11 executes processing according to these programs. The RAM is used as a work area when the CPU 11 executes processing. The storage unit 12 may further include a non-volatile storage medium (e.g., NVRAM) whose contents can be electrically rewritten. The NVRAM stores data that needs to be retained even when the power to the image forming system 1 is turned off. The NVRAM may store programs.

[0016] The CPU 11 controls all parts of the image forming system 1 and implements various functions by executing processes according to the programs stored in the memory unit 12. In the following, the processes executed by the CPU 11 will be described as processes executed by the main controller 10.

[0017] The communication interface 15 is configured to enable data communication with an information processing apparatus 5 such as a personal computer. The communication interface 15 may be capable of communicating with the information processing apparatus 5 in accordance with a communication scheme such as USB communication, Bluetooth (registered trademark) communication, wired LAN, or wireless LAN, for example.

[0018] When the main controller 10 receives image data to be printed from an external device (e.g., the information processing apparatus 5) via the communication interface 15, the main controller 10 inputs various commands to the print controller 20 and the conveyance controller 40 so that an image based on the image data is formed on a sheet Q (see FIG. 2).

[0019] The image forming system 1 further includes a recording head 21, an ink tank 22, a head drive circuit 23, a media sensor 25, a carriage conveyance mechanism 26, a CR motor 31, a first motor drive circuit 32, a first encoder 33, and a first signal processing circuit 34. The carriage conveyance mechanism 26 includes a carriage 30 and reciprocates the carriage 30 in a main scanning direction. The carriage 30 carries the recording head 21 and the media sensor 25. When the carriage 30 moves, the recording head 21 and the media sensor 25 also move together with the carriage 30. The recording head 21 ejects ink toward the sheet Q. The media sensor 25 detects the sheet Q. In the present embodiment, the media sensor 25 further detects a first detected portion 51 and a second detected portion 52 (see FIG. 2) described later. In the present embodiment, the carriage 30 carries only one media sensor 25.

[0020] The CR motor 31 is a drive source for the carriage 30. The print controller 20 controls conveyance of the carriage 30 by the carriage conveyance mechanism 26 by controlling the CR motor 31 in accordance with a motor drive command from the main controller 10. The print controller 20 further controls the ink ejection operation by the recording head 21 in accordance with an ink ejection command from the main controller 10. Through these controls, the print controller 20 forms the aforementioned image on the sheet Q.

[0021] The ink tank 22 is filled with ink. In the present embodiment, the ink tank 22 is not mounted on the carriage 30, and is arranged at a predetermined position in the image forming system 1. The recording head 21 is connected to the ink tank 22 via a tube (not shown). Ink is supplied to the recording head 21 from the ink tank 22 through the tube, and the recording head 21 ejects the ink.

[0022] The head drive circuit 23 drives the recording head 21 in accordance with a control signal from the print controller 20. The carriage conveyance mechanism 26 transmits the rotational force generated by the CR motor 31 to the carriage 30. The carriage 30 is reciprocated along the main scanning direction by the CR motor 31 and the carriage conveyance mechanism 26. The main scanning direction is orthogonal to the sub-scanning direction. The sub-scanning direction is the conveyance direction of the sheet Q by a sheet conveyance mechanism 41 which will be described later.

[0023] The CR motor 31 is, for example, in the form of a direct current motor. The first motor drive circuit 32 drives the CR motor 31 by supplying drive power corresponding to the operation amount input from the print controller 20 to the CR motor 31.

[0024] For example, the first motor drive circuit 32 may apply a voltage or a current corresponding to the operation amount to the CR motor 31 to drive the CR motor 31. Further, for example, the first motor drive circuit 32 may drive the CR motor 31 by PWM (pulse width modulation) control.

[0025] The first encoder 33 outputs a signal corresponding to the displacement of the carriage 30 in the main scanning direction (hereinafter referred to as the first encoder signal). The first encoder 33 of the present embodiment is in the form of a rotary encoder. The first signal processing circuit 34 calculates a count value to be described later based on the first encoder signal input from the first encoder 33, and detects the speed Vx of the carriage 30 based on the count value. The count value and the speed Vx are input to the print controller 20. The count value and the speed Vx may be further input to the main controller 10.

[0026] The print controller 20 detects the position Px of the carriage 30 based on the count value input from the first signal processing circuit 34. Then, the print controller 20 determines an input variable for the CR motor 31 based on the detected position Px of the carriage 30 and the speed Vx input from the first signal processing circuit 34, and controls the CR motor 31 to realize transport control of the carriage 30 in accordance with the motor drive command from the main controller 10.

[0027] The print controller 20 further inputs a control signal to the head drive circuit 23, based on the detected position Px of the carriage 30, to implement ink ejection control in accordance with the ink ejection command from the main controller 10. As a result, ink for forming the image to be printed on the paper Q is ejected from the recording head 21 onto the paper Q.

[0028] The image forming system 1 further comprises a paper transport mechanism 41, a PF motor 43, a second motor drive circuit 44, a second encoder 45, and a second signal processing circuit 46. The transport controller 40 controls the transport of the paper Q by controlling the PF motor 43 according to transport commands from the main controller 10.

[0029] As shown in Figures 1 and 2, the paper transport mechanism 41 includes a transport roller 42. The transport roller 42 is positioned upstream of the recording head 21 in the sub-scanning direction and extends in the main scanning direction. The transport roller 42 rotates by receiving rotational force from the PF motor 43, thereby transporting the paper Q, which is transported from further upstream, to the downstream side in the sub-scanning direction. The paper Q is transported in the sub-scanning direction in accordance with the operation of the recording head 21, that is, as an image is formed by the recording head 21.

[0030] The PF motor 43 is, for example, a DC motor. The second motor drive circuit 44 drives the PF motor 43 by applying drive power to the PF motor 43 according to the manipulated amount input from the transport controller 40. In this embodiment, the second encoder 45 is a rotary encoder. The second encoder 45 is, for example, located on the rotating shaft of the PF motor 43 or the rotating shaft of the transport roller 42. The second encoder 45 outputs a signal (hereinafter referred to as the second encoder signal) corresponding to the rotation of the rotating shaft on which it is located.

[0031] The second signal processing circuit 46 detects the amount and speed of rotation of the transport roller 42 based on the second encoder signal input from the second encoder 45. The amount and speed of rotation of the transport roller 42 correspond to the amount and speed of paper Q transported by the rotation of the transport roller 42.

[0032] The amount of rotation and rotational speed detected by the second signal processing circuit 46 are input to the transport controller 40. Based on the amount of rotation and rotational speed input from the second signal processing circuit 46, the transport controller 40 determines the operation amount for the PF motor 43 and controls the PF motor 43. In this way, the transport controller 40 controls the transport of the paper Q by the transport rollers 42.

[0033] The specific configuration of the carriage transport mechanism 26 will be described with reference to Figure 2. The carriage transport mechanism 26 comprises a carriage 30, a belt mechanism 27, a first guide rail 28, and a second guide rail 29. The belt mechanism 27 comprises a drive pulley 27a, a driven pulley 27b, and a belt 27c. The drive pulley 27a and the driven pulley 27b are arranged along the main scanning direction. The belt 27c is wound between the drive pulley 27a and the driven pulley 27b.

[0034] The carriage 30 is fixed to the belt 27c. In the belt mechanism 27, the drive pulley 27a rotates in response to the rotational force from the CR motor 31. As the drive pulley 27a rotates, the belt 27c and the driven pulley 27b rotate in response.

[0035] The first and second guide rails 28 and 29 extend along the main scanning direction. The first and second guide rails 28 and 29 are spaced apart from each other in the sub-scanning direction. The belt mechanism 27 is located, for example, on the first guide rail 28. The first and second guide rails 28 and 29 have, for example, convex walls (not shown) that extend along the main scanning direction. These walls restrict the movement direction of the carriage 30 to the main scanning direction.

[0036] The carriage 30 moves along the first and second guide rails 28 and 29 in the main scanning direction, in conjunction with the rotation of the belt 27c, while its direction of movement is restricted by the first and second guide rails 28 and 29. The recording head 21 and media sensor 25 move together with the carriage 30 in the main scanning direction as the carriage 30 moves.

[0037] The image forming system 1 further includes a platen 50, as shown in Figure 2. The platen 50 supports the paper Q transported by the paper transport mechanism 41. That is, the paper Q is transported on the platen 50. The length of the platen 50 in the main scanning direction is longer than the length of the paper Q in the main scanning direction.

[0038] The platen 50 is a single, integrally formed component. It is formed and positioned such that the point of impact on the paper Q when ink ejected from the recording head 21 lands on the paper Q is located on the platen 50. In other words, the platen 50 extends along the main scanning direction so as to face the recording head 21 as it moves with the carriage 30. In this embodiment, as illustrated in Figure 2, the platen 50 extends in the sub-scanning direction from the back of the first guide rail 28 to the back of the second guide rail 29.

[0039] The first encoder 33 is positioned on the rotating body to be detected. The rotating body to be detected may be any rotating body configured such that its rotation and the movement of the carriage 30 are synchronized or follow each other. In other words, the carriage 30 moves together with the rotation of the rotating body to be detected. The rotating body to be detected may be, for example, a CR motor 31 (more specifically, the rotating shaft of the CR motor 31), a drive pulley 27a, or a driven pulley 27b. In this embodiment, the rotating body to be detected is, for example, a CR motor 31, and as shown in Figure 2, the first encoder 33 is provided on the CR motor 31. The first encoder 33 outputs a pulse each time the CR motor 31 rotates by a certain angle.

[0040] More specifically, the first encoder 33 comprises a disc-shaped scale (not shown) and an optical sensor (not shown). The scale is fixed to the rotating body to be detected such that its center is positioned on the axis of rotation of the rotating body to be detected. In other words, the scale rotates integrally with the rotating body to be detected.

[0041] The scale comprises a row of slits (not shown). The row of slits includes a plurality of slits arranged at equal intervals from one another along the circumferential direction and around the entire circumference of the scale. The optical sensor is fixedly positioned within the housing of the image forming system 1, facing the row of slits. The optical sensor has a detection position for detecting the presence or absence of a slit. Each slit passes through the detection position as the scale rotates. The optical sensor outputs the aforementioned first encoder signal in accordance with the displacement of the carriage 30 in the main scanning direction. The first encoder signal includes the aforementioned pulse, which is output each time a slit passes through the detection position of the optical sensor (i.e., each time the CR motor 31 rotates by a certain angle).

[0042] The optical sensor of this embodiment outputs a high-level signal while the slit is passing through the detection position and a low-level signal when the slit is not present at the detection position. As a result, a pulsed first encoder signal is output in response to the occurrence of the event of the slit passing through the optical sensor. The first encoder signal is an analog signal. The first encoder signal is input to the first signal processing circuit 34.

[0043] The image forming system 1 may also be equipped with two optical sensors. In this case, the two optical sensors will be referred to as the A-phase sensor and the B-phase sensor, respectively. The detection position of the A-phase sensor will be referred to as the A-phase detection position, and the detection position of the B-phase sensor will be referred to as the B-phase detection position. The first encoder signal from the A-phase sensor will be referred to as the A-phase encoder signal, and the first encoder signal from the B-phase sensor will be referred to as the B-phase encoder signal. The A-phase sensor and the B-phase sensor are spaced apart from each other along the direction of the slit arrangement (i.e., along the circumferential direction of the scale). That is, the A-phase detection position and the B-phase detection position are spaced apart from each other along the circumferential direction of the scale. Therefore, the A-phase encoder signal and the B-phase encoder signal have a phase difference of π / 2 from each other. The A-phase encoder signal and the B-phase encoder signal are input to the first signal processing circuit 34. In this embodiment, as an example, the first encoder 33 will be described as being equipped with both an A-phase sensor and a B-phase sensor.

[0044] The first signal processing circuit 34 detects the pulse edges of the A-phase encoder signal and the B-phase encoder signal, respectively. The pulse edges include rising edges that change from a low level to a high level (rising) and falling edges that change from a high level to a low level.

[0045] The first signal processing circuit 34 counts pulse edges each time a pulse edge is detected in either the A-phase encoder signal or the B-phase encoder signal. Specifically, each time a pulse edge is detected in either direction, the count value of the pulse edge is incremented or decremented depending on the signal level of the other signal at the time of detection. For example, when the carriage 30 is moving in the main scanning direction, the count value may be incremented each time a pulse edge is detected, and when the carriage 30 is moving in the opposite direction to the main scanning direction (hereinafter referred to as the "home direction"), the count value may be decremented each time a pulse edge is detected. The count value may be reset to an initial value (e.g., zero) when a predetermined clear condition is met. The predetermined clear condition may include, for example, that the carriage 30 has moved to the home position 61 (see Figure 2).

[0046] As described above, the first signal processing circuit 34 outputs the count value to the print controller 20. The first signal processing circuit 34 further detects the speed Vx of the carriage 30 based on the time interval at which the pulse edge of the A-phase encoder signal is detected, or the time interval at which the pulse edge of the B-phase encoder signal is detected. The first signal processing circuit 34 outputs the detected speed Vx to the print controller 20.

[0047] The media sensor 25 is positioned on the lower surface of the carriage 30 (the surface facing the platen 50) so as to face the platen 50. The media sensor 25 detects objects such as paper Q and the first and second detection units 51 and 52. The media sensor 25 includes a light-emitting unit (not shown) and a light-receiving unit (not shown). The light-emitting unit includes a light-emitting element such as a light-emitting diode. The light-receiving unit receives light and outputs a detection signal indicating the amount of light received.

[0048] The main controller 10 outputs a light emission instruction to the light emission unit during the period in which the object to be detected should be detected. The light emission instruction includes the amount of light emitted. When the light emission unit receives a light emission instruction from the main controller 10, it emits light of the specified amount in a predetermined emission direction. The emission direction is, for example, perpendicular or approximately perpendicular to the paper Q on the platen 50 and directed toward the platen 50.

[0049] The light emitted from the light-emitting unit is reflected by the platen 50 or an object such as the paper Q supported by the platen 50, and the reflected light is received by the light-receiving unit. In this embodiment, the emitted light can also be emitted by the first and second detection units 51 and 52 and reflected by the first and second detection units 51 and 52.

[0050] The amount of reflected light received by the light-receiving unit varies depending on the distance from the light-emitting unit to the object being detected, as well as the physical characteristics of the object, such as its shape, material, and color. The media sensor 25 outputs a detection signal indicating the amount of light received by the light-receiving unit to the print controller 20 and the main controller 10. For example, the media sensor 25 outputs a detection signal to the print controller 20 and the main controller 10 such that the voltage increases as the amount of light received increases.

[0051] The print controller 20 detects the target based on the detection signal input from the media sensor 25. The print controller 20 may detect the target in any way based on the detection signal. For example, a light reception range may be set for each target. The print controller 20 may then determine the target based on which target's light reception range the light reception amount indicated by the detection signal falls within. Alternatively, for example, a range of change in light reception amount may be set for each target. The print controller 20 may then detect a target when a change in light reception occurs that falls within the range of change in light reception amount for any of the targets. The main controller 10 may also detect the target in the same way as the print controller 20. Alternatively, the detection result from the print controller 20 may be transmitted to the main controller 10. Conversely, the main controller may detect the target, and the print controller 20 may acquire the detection result.

[0052] When printing is not taking place, the carriage 30 basically remains in the home position 61 shown in Figure 2. When the main controller 10 acquires image data from an external source, it performs a pre-scan, which will be described later, prior to printing. During the pre-scan, the carriage 30 is moved at least once back and forth in the main scanning direction. Based on the detection signal from the media sensor 25 during the pre-scan, the main controller 10 detects the presence and width (i.e., length in the main scanning direction) of the paper Q. After the pre-scan is completed, the main controller 10 outputs a motor drive command and an ink ejection command to perform image formation on the paper Q. Specifically, each time a certain amount of paper Q is transported in the sub-scanning direction, the carriage 30 is moved back and forth in the main scanning direction, and ink is ejected from the recording head 21 onto the paper Q during this back and forth movement.

[0053] (2) Calculation of carriage position during image formation Ink ejection onto paper Q by the recording head 21 is performed based on the position Px of the carriage 30 (and consequently the position of the recording head 21) detected by the print controller 20. The print controller 20 basically detects the position Px of the carriage 30 based on a count value from the first signal processing circuit 34. While moving the carriage 30 in the main scanning direction and the home direction, the print controller 20 ejects ink from the recording head 21 according to the detected position Px of the carriage 30, based on the ink ejection command from the main controller 10.

[0054] The print controller 20 may detect the position Px of the carriage 30 by multiplying the count value by the design travel distance per count (hereinafter referred to as "theoretical unit travel distance").

[0055] However, if the actual distance traveled per count does not match the theoretical unit travel distance, the position Px of the carriage 30 cannot be detected correctly. In other words, the position Px of the carriage 30 detected by the print controller 20 does not match the actual position of the carriage 30. Possible causes for the actual distance traveled per count not matching the theoretical unit travel distance include errors in the spacing of the slit rows of the first encoder 33 and errors in the pitch of the belt 27c.

[0056] To solve this problem, for example, the carriage 30 may be moved in one direction from one end to the other of its movable range, and the actual distance the carriage 30 moves per count (hereinafter referred to as "correction value Y") may be calculated based on the change in the count value during that time and the design distance of the movable range. However, with this method, the correction value Y may not be calculated accurately due to the effects of the deflection of the belt 27c, etc.

[0057] In other words, as illustrated in Figure 3 as an example of "actual characteristics," even when the CR motor 31 is started to move the carriage 30 to one end of its movable range (for example, the home position 61), immediately after the start, the CR motor 31 may not move even if it is rotating, and the carriage 30 may actually start moving only after the CR motor 31 has rotated a very small amount (the count value has increased slightly).

[0058] In Figure 3, the vertical axis shows the count value from the first signal processing circuit 34. The horizontal axis shows the position Px of the carriage 30 in the main scanning direction, with the home position 61 as the reference (origin "0"). The origin "0" indicates that the count value is "0" on the vertical axis. "Movable distance" indicates the length of the movable range. Figure 3 shows an example where there is an error between the actual movable distance and the theoretical (design) movable distance. Figure 3 also illustrates that the count value and the position Px of the carriage 30 change linearly, as exemplified as the "theoretical characteristics". In other words, theoretically, the count value reaches Ce0 when the carriage 30 reaches the other end of the movable range. Figure 3 also illustrates that in reality, it does not follow the "theoretical specifications" and changes as exemplified as the "actual characteristics". In the "actual characteristics", the final count value Ce does not match the design count value Ce0. Furthermore, even when the CR motor 31 starts rotating and the count value begins to increase, the carriage 30 does not move immediately due to the deflection of the belt 27c and other mechanical factors. Moreover, even when the carriage 30 is moved to the other end of its movable range and stops, the CR motor 31 rotates a small amount due to the deflection of the belt 27c and other mechanical factors, which also increases the count value. For this reason, even if the correction value Y is calculated using this "actual characteristic," a highly accurate correction value Y cannot be expected. Also, Figure 3 shows an example where there is an error between the actual width of the paper Q and its theoretical width.

[0059] Based on the problems described above, the print controller 20 of this embodiment calculates a correction value Y by a method described later. Then, the position Px of the carriage 30 is detected using this correction value Y. In order to calculate the correction value Y, the image forming system 1 of this embodiment is provided with a first detection unit 51 and a second detection unit 52, as illustrated in Figures 2 and 3.

[0060] The first and second detectable parts 51 and 52 are spaced apart from each other along the main scanning direction. The first and second detectable parts 51 and 52 are located in positions that can be detected by the media sensor 25, and that can be detected by the media sensor 25 while the carriage 30 is moving (i.e., while it is not stopped). The first and second detectable parts 51 and 52 are located on a single component (i.e., a integrally formed component) in the image forming system 1.

[0061] In this embodiment, the first and second detection units 51 and 52 are provided on the paper Q. Specifically, the first end of the paper Q is set as the first detection unit 51, and the second end of the paper Q is set as the second detection unit 52. The first end of the paper Q corresponds to the upstream end of the paper Q in the main scanning direction. The second end of the paper Q corresponds to the downstream end of the paper Q in the main scanning direction.

[0062] In other words, in the image forming system 1 of this embodiment, the first and second detection units 51 and 52 are not independently provided components. In this embodiment, the first and second ends of the paper Q function as the first and second detection units 51 and 52. As will be described later, the first and second detection units 51 and 52 may each be provided independently of the paper Q.

[0063] When the time comes for printing to be performed, such as when acquiring image data from an external source, the print controller 20 first performs a pre-scan prior to printing. The pre-scan is performed for a specific purpose separate from image formation. This specific purpose may include one or more of the following: determining the presence or absence of paper Q on the platen 50; determining the width (length in the main scanning direction) of paper Q on the platen 50; determining whether the carriage 30 is in a state where it can move back and forth properly along the main scanning direction; and determining whether the state of the first encoder 33 (for example, the state of the slit row in the scale) is normal.

[0064] During pre-scanning, the carriage 30 is moved at least once back and forth from the home position 61 in the main scanning direction. The print controller 20 acquires a first count value C1, a second count value C2, a third count value C3, and a fourth count value C4 while the carriage 30 is moving in the main scanning direction due to pre-scanning, and stores them in a memory unit (not shown).

[0065] The first count value C1 corresponds to the count value from the first signal processing circuit 34 when the first detected unit 51 is detected by the media sensor 25 while the carriage 30 is moving in the main scanning direction. The second count value C2 corresponds to the count value from the first signal processing circuit 34 when the second detected unit 52 is detected by the media sensor 25 while the carriage 30 is moving in the main scanning direction.

[0066] The third count value C3 corresponds to the count value from the first signal processing circuit 34 when the first edge of the paper Q is detected by the media sensor 25 while the carriage 30 is moving in the main scanning direction. The fourth count value C3 corresponds to the count value from the first signal processing circuit 34 when the first edge of the paper Q is detected by the media sensor 25 while the carriage 30 is moving in the main scanning direction.

[0067] In this embodiment, for example, the count value is set to an initial value (e.g., zero) when the carriage 30 is in the home position 61. Therefore, in this embodiment, as the carriage 30 moves from the home position 61 toward the main scanning direction, the count value is incremented from zero. Conversely, as the carriage 30 moves toward the home direction, the count value is decremented.

[0068] In this embodiment, as described above, the first edge of paper Q coincides with the first detected area 51, and the second edge of paper Q coincides with the second detected area 52. Therefore, in this embodiment, the first count value C1 is equal to the third count value C3, and the second count value is equal to the fourth count value.

[0069] The print controller 20 acquires the first and second count values ​​C1 and C2 stored by the prescan, and the theoretical reference distance Dr0. As illustrated in Figure 3, the theoretical reference distance Dr0 is the design distance between the first detected unit 51 and the second detected unit 52. The theoretical reference distance Dr0 may be acquired in any way. For example, the theoretical reference distance Dr0 may be pre-stored in the storage unit of the print controller 20 or the storage unit 12 of the main controller 10. In this embodiment, the theoretical reference distance Dr0 is equal to the design width of the paper Q.

[0070] The print controller 20 calculates the correction value Y based on the acquired first and second count values ​​C1 and C2 and the theoretical reference distance Dr0. Specifically, the print controller 20 calculates the correction value Y as the value obtained by dividing the theoretical reference distance Dr0 by the actual count difference. The actual count difference corresponds to the difference between the first count value C1 and the second count value C2 (see Figure 3).

[0071] The print controller 20 further acquires the print start position Pst. The print start position Pst is stored in advance, for example, the print controller 20 or the main controller 10. The print start position Pst may be, for example, the first edge of the paper Q, a position offset by a predetermined distance upstream or downstream from the first edge in the main scanning direction, or a position offset by a predetermined distance upstream from the center position of the paper Q in the main scanning direction. Figure 3 shows an example where the print start position Pst is set to the first edge of the paper Q.

[0072] The print controller 20 calculates the print start count value Cst, which is a count value corresponding to the acquired print start position Pst. The print start count value Cst is calculated based on the third and fourth count values ​​C3 and C4 stored by the prescan. Specifically, for example, if the print start position Pst is set to the first edge of the paper Q, the print controller 20 calculates the third count value C3 as the print start count value Cst. Also, for example, if the print start position Pst is set to a position offset by a predetermined distance from the first edge of the paper Q in the main scanning direction, the print controller 20 calculates the number of counts corresponding to that predetermined distance (hereinafter, "offset count") based on the third and fourth count values ​​C3 and C4 and the theoretical value of the width of the paper Q (length in the main scanning direction). Then, the print start count value Cst is calculated based on the calculated offset count. Specifically, for example, the value obtained by adding the offset count to the third count value C3 is calculated as the print start count value Cst. In this embodiment, as described above, the print start position Pst is set to the first edge of the paper Q. Therefore, the third count value C3, which corresponds to the print start position Pst, is set as the print start count value Cst (see Figure 3).

[0073] In this way, once the correction value Y and the print start count value Cst are calculated, the print controller 20 moves the carriage 30 and ejects ink from the recording head 21 for image formation based on the ink ejection command from the main controller 10. Specifically, the carriage 30 is moved from the home position 61 in the main scanning direction according to the speed profile. Then, when the count value reaches the print start count value Cst (i.e., when the carriage 30 reaches the print start position Pst), ink ejection begins according to the ink ejection command.

[0074] Specifically, the print controller 20 calculates the virtual carriage position Pdash using the following equation (1). The virtual carriage position Pdash is the position Px of the carriage 30 recognized by the print controller 20.

[0075] Pdash = Pst + Cn * Y ... (1) In equation (1) above, the variable Cn represents the relative count value from the print start count value Cst (see Figure 3). In other words, the change in the count value from the print start count value Cst corresponds to the variable Cn. Therefore, the second term on the right-hand side of equation (1) "Cn*Y" (i.e., the product of the variable Cn and the correction value Y) represents the distance traveled from the print start position Pst in the main scanning direction. In other words, the virtual carriage position Pdash is obtained by adding the distance traveled using the correction value Y to the print start position Pst. The "correction characteristics" illustrated by the dashed line in Figure 3 show an example of the relationship between the count value and the virtual carriage position Pdash.

[0076] After the carriage 30 reaches the print start position Pst, the print controller 20 calculates the virtual carriage position Pdash using the above formula (1). Then, based on the calculated virtual carriage position Pdash, it ejects ink onto the paper Q to form an image on the paper Q. For example, suppose the ink ejection command from the main controller 10 instructs the printer to eject ink between positions Pa and Pb, and not to eject ink between positions Pb and Pc. In this case, the print controller 20 ejects ink from the moment the virtual carriage position Pdash coincides with Pa until it coincides with Pb. Then, it does not eject ink from the moment the virtual carriage position Pdash coincides with Pb until it coincides with Pc.

[0077] In this way, by controlling ink ejection from the print start position Pst based on the virtual carriage position Pdash, image formation at the desired position on the paper Q can be performed with high precision.

[0078] (3) Print control processing The print control process performed by the print controller 20 will be explained with reference to Figure 4. When the main controller 10 receives a print instruction (including image data) from an external source, various commands based on that print instruction are input from the main controller 10 to the print controller 20. Based on these commands, the print controller 20 executes the print control process shown in Figure 4. When this print control process is executed, the CR motor 31 and the recording head 21 are driven, and the image indicated by the image data is formed on the paper Q. The print control process may be executed based on software or by hardware processing.

[0079] When the print controller 20 starts the print control process, it initiates an initial drive for pre-scanning in S110. The initial drive includes moving the carriage 30 back and forth from the home position 61. After initiating the initial drive, the print controller 20 acquires the first to fourth count values ​​C1 to C4 in S120. Specifically, as described above, the first to fourth count values ​​C1 to C4 are acquired based on the detection signal input from the media sensor 25 during movement and the count value from the first signal processing circuit 34.

[0080] Then, after the initial drive is completed, the print controller 20 calculates the correction value Y in S130. Specifically, the correction value Y is calculated using the method described above, based on the first and second count values ​​C1 and C2 obtained in S120 and the theoretical reference distance Dr0.

[0081] Furthermore, in S140, the print controller 20 obtains the print start position Pst, and calculates the print start count value Cst using the method described above, based on the print start position Pst and the third and fourth count values ​​C3 and C4 obtained in S120. With these steps completed, the preparations for calculating the virtual carriage position Pdash are complete.

[0082] In S150, the print controller 20 executes the printing process. Specifically, as described above, it transports a certain amount of paper Q in the sub-scanning direction, and each time, it moves the carriage 30 back and forth in the main scanning direction, ejecting ink from the recording head 21 onto the paper Q. This forms an image on the paper Q. In the ink ejection from the recording head 21 during the printing process, when the carriage 30 reaches the print start position Pst (i.e., the count value reaches the print start count value Cst), the print controller 20 calculates the virtual carriage position Pdash using the aforementioned equation (1) for at least the range in which ink should be ejected onto the paper Q. Then, it ejects ink based on that virtual carriage position Pdash.

[0083] (4) Effects of the embodiment and correspondence of wording In the image forming system 1 of the embodiment described above, the first and second detected units 51 and 52 are detected using a single media sensor 25 for the purpose of calculating the correction value Y and the virtual carriage position Pdash based on the correction value Y (hereinafter collectively referred to as "correction calculation"). Moreover, the media sensor 25 is not additionally provided for the correction calculation, but is provided for purposes other than the correction calculation (such as detecting the presence or absence of paper, detecting both edges of the paper, etc.). In this embodiment, the media sensor 25, which is originally provided for purposes other than the correction calculation, is also used (shared) for the correction calculation.

[0084] Therefore, while keeping the cost of the image forming system 1 down, the distance traveled by the carriage 30, and consequently the position of the carriage 30 (specifically, the virtual carriage position Pdash), can be calculated with high accuracy.

[0085] Furthermore, in this embodiment, the detection of the first and second detected units 51 and 52 by the media sensor 25 is performed while the carriage 30 is moving. Therefore, the aforementioned problem in the inkjet recording apparatus described in Patent Document 1 (the problem of reduced correction accuracy due to the deflection of the belt 27c, etc.) can be suppressed, and the calculation accuracy of the virtual carriage position Pdash can be improved.

[0086] Furthermore, in this embodiment, the calculation of the virtual carriage position Pdash using the correction value Y is performed from the print start position Pst. In other words, the virtual carriage position Pdash is not calculated from the start of carriage 30 movement to the print start position Pst, and is calculated only in the section where the virtual carriage position Pdash is required. Therefore, the calculation of the virtual carriage position Pdash can be performed efficiently as needed.

[0087] Furthermore, in this embodiment, the first and second edges of the paper Q are set to the first and second detection units 51 and 52. Therefore, the first and second count values ​​C1 and C2 necessary for calculating the correction value Y, and the third and fourth count values ​​C3 and C4 necessary for calculating the print start count value Cst can be obtained from the detection results of essentially two locations. As a result, the processing load related to the correction calculation can be reduced.

[0088] Furthermore, in this embodiment, the first and second detection units 51 and 52 are provided on a single component. Specifically, in this embodiment, the first and second detection units 51 and 52 are set on paper Q. Therefore, deviations of the actual distance between the first and second detection units 51 and 52 from the theoretical reference distance dr0 are suppressed.

[0089] Here, the correspondence between terms is clarified. In this embodiment, paper Q corresponds to an example of an object and sheet in this disclosure. Recording head 21 corresponds to an example of an ejection head in this disclosure. The combination of carriage 30 and recording head 21 corresponds to an example of a moving body in this disclosure. The first encoder 33 and the first signal processing circuit 34 correspond to an example of a rotation amount information output unit in this disclosure. Media sensor 25 corresponds to an example of a detection unit in this disclosure. Print controller 20 corresponds to an example of a controller in this disclosure. Ejecting ink onto paper Q corresponds to an example of a predetermined operation in this disclosure, and forming an image on paper Q by ejecting ink corresponds to an example of processing an object in this disclosure. Main scanning direction corresponds to an example of a movement direction in this disclosure. First count value C1 corresponds to an example of first rotation amount information in this disclosure, and second count value C2 corresponds to an example of second rotation amount information in this disclosure. Theoretical reference distance corresponds to an example of theoretical distance information in this disclosure. Print start position Pst corresponds to an example of a specified position in this disclosure.

[0090] Furthermore, the process in S110 corresponds to an example of the movement process in this disclosure. The process in S120 corresponds to an example of the rotation amount information acquisition process in this disclosure. The process in S130 corresponds to an example of the correction value calculation process in this disclosure. The process in S150 corresponds to an example of the movement distance calculation process and control process in this disclosure.

[0091] [2. Other Embodiments] Although embodiments of the present disclosure have been described above, the present disclosure is not limited to the embodiments described above and can be implemented in various modified forms.

[0092] (1) In the above embodiment, the first and second ends of the paper Q were set as the first and second detection units 51 and 52. However, the first and second detection units 51 and 52 may be located anywhere.

[0093] For example, as illustrated in Figure 5, the platen 50 may be provided with first and second detection units 51 and 52. In the example in Figure 5, the first detection unit 51 is provided on the platen 50 on the home side of the area where the paper Q is transported, and the second detection unit 52 is provided on the platen 50 on the main scanning side of the area where the paper Q is transported. The first and second detection units 51 and 52 may be provided on the platen 50 in any way. For example, the first and second detection units 51 and 52 may be integrally formed with the platen 50 by a predetermined integral molding method (e.g., injection molding). Alternatively, the first and second detection units 51 and 52 may be prepared separately from the platen 50 and attached to the platen 50.

[0094] When the first and second detection units 51 and 52 are located in different parts of the paper Q, the first to fourth count values ​​C1 to C4 will take different values ​​from each other. However, even in this case, the correction value Y can be calculated in basically the same way as in the above embodiment, and the virtual carriage position Pdash can also be calculated.

[0095] Furthermore, one or both of the first and second detection units 51 and 52 may be provided in a location different from either the paper Q or the platen 50. (2) In the above embodiment, the correction calculation was performed in the print controller 20, but the correction calculation may be performed anywhere. For example, part or all of the correction calculation may be performed in a place other than the print controller 20 (e.g., the main controller 10).

[0096] (3) The first encoder 33 may be, for example, a linear encoder. Alternatively, the rotation amount information output unit of this disclosure may not have an encoder and may be configured to output rotation amount information based on a detection result from a rotation detection means of a different form than an encoder.

[0097] (4) The carriage 30 may be equipped with additional sensors in addition to the media sensor 25. However, even in this case, the first to fourth count values ​​C1 to C4 are obtained in the correction calculation based only on the detection result of the single media sensor 25.

[0098] (5) In the above embodiments, a carriage 30 and a recording head 21 were given as examples of the moving body of the present disclosure, but the moving body of the present disclosure is not limited to the carriage 30 and the recording head 21. The present disclosure can be applied to any moving body configured to process an object by performing predetermined operations during the moving process.

[0099] Furthermore, in the above embodiment, ink ejection from the recording head 21 to paper Q was exemplified as an example of a predetermined operation by the moving body, and image formation on paper Q was exemplified as an example of object processing. However, neither the predetermined operation nor the object processing is limited to these. In other words, the technology of this disclosure is not limited to application to the image forming system 1. For example, the technology of this disclosure can be applied to printers other than inkjet printers (e.g., other serial printers) and garment printers. The technology of this disclosure can also be applied to various devices other than printers. For example, the technology of this disclosure can be applied to machine tools such as machines that print wiring patterns. The technology of this disclosure can be applied to various control systems that transport a moving body using motor control.

[0100] (6) The function of one component in the above embodiment may be distributed among multiple components. The functions of multiple components may be integrated into one component. Some of the configurations of the above embodiment may be omitted. At least some of the configurations of the above embodiment may be added to or replaced with the configurations of other above embodiments. Any aspect of the technical concept specified by the wording of the claims is an embodiment of the present disclosure. [Explanation of Symbols]

[0101] 1,100…Image forming system, 10…Main controller, 11…CPU, 12…Storage unit, 20…Print controller, 21…Recording head, 25…Media sensor, 30…Print controller, 30…Carriage, 31…CR motor, 33…First encoder, 34…First signal processing circuit, 50…Platen, 51…First detected unit, 52…Second detected unit, Q…Paper.

Claims

1. Motor and, A moving body configured to be moved along a predetermined direction of movement by the motor and to process an object by performing predetermined operations during the movement process, A single detection unit mounted on the moving body, configured to detect a first detected part and a second detected part while the moving body is moving, wherein the first detected part and the second detected part are spaced apart from each other along the direction of movement and are detected by the detection unit while the moving body is moving along the direction of movement, A rotation amount information output unit configured to output rotation amount information indicating the amount of rotation of the motor, Controller and Equipped with, The aforementioned controller, A movement process in which the motor moves the moving body along the direction of movement, A rotation amount information acquisition process that acquires first rotation amount information and second rotation amount information, which are the rotation amount information from the rotation amount information output unit, when the first detected unit and the second detected unit are detected by the detection unit during the movement of the moving body by the movement process, A correction value calculation process calculates a correction value that directly or indirectly indicates the actual moving distance of the moving body per predetermined rotation amount of the motor, based on the first rotation amount information and the second rotation amount information obtained by the rotation amount information acquisition process, and theoretical distance information which is information indicating the design distance between the first detected unit and the second detected unit. A distance calculation process that calculates the distance traveled by the moving body using the rotation amount information from the rotation amount information output unit and the correction value calculated by the correction value calculation process, It is configured to perform, The moving body includes a discharge head configured to eject ink, The predetermined operation includes forming an image on the sheet by ejecting ink from the ejection head onto the sheet, which is the object. The first detected part is the upstream end of the sheet in the direction of movement, The second detected part is the downstream end of the sheet in the direction of movement, Control system.

2. A control system according to claim 1, The rotation amount information output unit includes a rotary encoder configured to output a signal each time the motor rotates by a certain angle, and is configured to count the signal from the rotary encoder and output the count value as the rotation amount information. The correction value calculation process calculates the correction value which directly or indirectly indicates the actual distance traveled by the moving body per count of the signal. Control system.

3. A control system according to claim 2, The correction value calculation process calculates the correction value by dividing the design distance indicated by the theoretical distance information by the actual count difference, and the actual count difference is the difference between the count values ​​indicated by the first rotation amount information and the second rotation amount information, respectively. Control system.

4. A control system according to claim 3, The aforementioned movement distance calculation process is a control system that calculates the movement distance of the moving body from the predetermined position by multiplying the amount of change in the count value from the predetermined position when the moving body moves from the predetermined position in the direction of movement by the correction value calculated by the correction value calculation process.

5. A control system according to claim 4, The aforementioned distance calculation process further calculates the position of the moving body based on the predetermined position and the calculated distance the moving body travels from the predetermined position. The controller is further configured to execute a control process that controls the predetermined operation performed by the moving body based on the position of the moving body calculated by the distance calculation process. Control system.

6. A control system according to any one of claims 1 to 5, A control system in which the first detected unit and the second detected unit are provided on a single component.

7. A control system according to claim 1, The platen is a single member that extends along the direction of movement so as to face the discharge head which is moving together with the moving body, The first detected unit and the second detected unit are provided on the platen. Control system.

8. A control system according to claim 1, The aforementioned controller further, A sheet detection process that detects the presence or absence of the sheet and / or the width of the sheet in the direction of movement based on the detection results of the detection unit for the upstream end and the downstream end of the sheet, A control system configured to perform the following actions.

9. A control system according to claim 1, The rotation amount information output unit is a control system comprising a rotary encoder configured to output a signal each time the motor rotates by a certain angle, and configured to output the rotation amount information based on the signal from the rotary encoder.

10. A control system according to claim 1, The controller is further configured to execute a control process that controls the predetermined operation by the moving body based on the distance traveled calculated by the distance traveled calculation process, thereby forming a control system.

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