Drive unit and conveying unit

Abstract

The present invention provides a drive device and a transport device equipped with a drive device that can reduce the deviation of a moving object from its target position. [Solution] The control unit performs reference position setting control by driving the abutment motor 51 in the forward direction to abut the abutment shaft 56 against the reference block 58, causing the abutment motor 51 to lose step, thereby positioning the abutment shaft 56 at the reference position. In reference position setting control, if the encoder detects the downward movement of the abutment shaft 56 due to the abutment motor 51 losing step and the amount of movement due to this movement, the control unit stores the amount of movement due to this movement. Then, when the control unit first positions the abutment shaft 56 at the target position after reference position setting control, it drives the abutment motor 51 in reverse to move the abutment shaft 56 by a distance obtained by subtracting the amount of movement due to this movement from the distance between the reference position and the target position.

Description

Technical Field

[0001] The present invention relates to a driving device and a conveying device.

Background Art

[0002] In a driving device that moves a moving body by a stepping motor and arranges it at a target position, after positioning the moving body at a reference position by hitting the moving body against a stopper member to cause the stepping motor to lose synchronization, the moving body is moved to the target position.

[0003] In such a driving device, when positioning the moving body at the reference position, the control pulse of the stepping motor is output to a sufficient amount to hit the moving body against the stopper member and cause the stepping motor to lose synchronization.

[0004] When the control system of the driving device cannot detect the loss of synchronization of the stepping motor, the control system continues to output the control pulse even after the loss of synchronization until a preset pulse amount is reached.

[0005] Due to its characteristics, the stepping motor may experience a phase shift due to vibration caused by the loss of synchronization. If the control pulse continues to be output in a state where the stepping motor has a phase shift, the stepping motor may unexpectedly reverse.

[0006] As a result, the position of the moving body may deviate from the reference position, and there may be a disadvantage that its position cannot be detected. As a result, the moving body may not be accurately arranged at the target position.

[0007] Here, Patent Document 1 discloses a technique for detecting the loss of synchronization of a stepping motor using a rotary encoder attached to the motor shaft of the stepping motor. By using such a technique, it becomes possible to detect when the stepping motor loses synchronization and stop the control pulse.

Prior Art Documents

Patent Documents

[0008] [Patent Document 1] Japanese Patent Publication No. 2000-166297 [Overview of the project] [Problems that the invention aims to solve]

[0009] However, the technique described above, which uses a rotary encoder to detect stepping motor step loss, is a feedback control method, meaning there is a time lag between the actual stepping motor step loss and the cessation of the control pulse. This time lag can cause the stepping motor to unintentionally reverse direction. As a result, the moving object cannot be accurately positioned at the reference position, and consequently, the position of the moving object, when moved from the reference position towards the target position, may deviate from the target position.

[0010] The present invention has been made in view of the above, and aims to provide a drive device and a transport device equipped with a drive device that can reduce the deviation of a moving object from its target position. [Means for solving the problem]

[0011] To achieve the above objective, the drive device of the present invention comprises a stepping motor, a moving body that moves by the drive of the stepping motor, a detection unit that detects the direction and amount of movement of the moving body, a stopper member against which the moving body abuts at a reference position of the moving body, and a control unit that performs reference position setting control to place the moving body at the reference position by driving the stepping motor in the forward direction to abut the moving body against the stopper member and causing the stepping motor to lose step, wherein in the reference position setting control, if the detection unit detects the movement of the moving body away from the stopper member due to the stepping motor losing step and the amount of movement due to the

[0012] The conveying device of the present invention comprises a drive unit having three or more stepping motors, three or more moving bodies, three or more detection units, and three or more abutting members, and a conveying unit having a planar abutting surface against which the moving bodies abut and for conveying an object to be conveyed, wherein when the conveying unit conveys an object to be conveyed, three or more of the moving bodies positioned at the target position are arranged to abut the abutting surface, and the three or more moving bodies abut the abutting surface at three or more positions that are not on the same straight line. [Effects of the Invention]

[0013] According to the present invention, it is possible to provide a drive device that can reduce the deviation of a moving object from its target position, and a conveying device equipped with the drive device. [Brief explanation of the drawing]

[0014] [Figure 1] This is a schematic diagram of an inkjet printing apparatus according to an embodiment. [Figure 2]It is a control block diagram of an inkjet printing apparatus shown in FIG. 1. [Figure 3] It is a perspective view showing a schematic configuration of a printing unit. [Figure 4] It is a perspective view showing a schematic configuration of a abutting mechanism unit. [Figure 5] It is a flowchart for explaining an operation of arranging an abutting shaft at a target position. [Figure 6] It is a flowchart for explaining an operation of arranging an abutting shaft at a target position. [Figure 7] It is a flowchart for explaining an operation of arranging an abutting shaft at a target position. [Figure 8] It is a flowchart for explaining an operation of arranging an abutting shaft at a target position. [Figure 9] (a) to (e) are explanatory diagrams of an operation of arranging an abutting shaft at a target position. [Figure 10] It is a diagram showing an example of a control pulse, an A-phase signal, and a B-phase signal of an encoder when a reverse rotation occurs due to out-of-tune of an abutting motor. [Figure 11] It is a diagram showing an example of a control pulse, an A-phase signal, and a B-phase signal of an encoder when an abutting motor goes out-of-tune immediately after the start of reference position detection control.

Embodiments for Carrying Out the Invention

[0015] Hereinafter, embodiments of the present invention will be described with reference to the drawings. The same or equivalent parts and components throughout the drawings are denoted by the same or equivalent reference numerals.

[0016] The embodiments shown below illustrate devices and the like for embodying the technical idea of this invention. The technical idea of this invention does not specify the materials, shapes, structures, arrangements, etc. of each component part as the following. The technical idea of this invention can be variously modified within the scope of the claims.

[0017] FIG. 1 is a schematic configuration diagram of an inkjet printing apparatus provided with a driving device according to an embodiment of the present invention. FIG. 2 is a control block diagram of the inkjet printing apparatus shown in FIG. 1. FIG. 3 is a perspective view showing a schematic configuration of a printing unit of the inkjet printing apparatus shown in FIG. 1. FIG. 4 is a perspective view showing a schematic configuration of a abutting mechanism unit of the inkjet printing apparatus shown in FIG. 1. In the following description, the direction orthogonal to the plane of FIG. 1 is defined as the front-rear direction. Also, the upper, lower, left, and right directions in the plane of FIG. 1 are defined as the up-down and left-right directions, respectively.

[0018] As shown in FIGS. 1 and 2, an inkjet printing apparatus 1 according to the present embodiment includes a conveyance unit 2, a conveyance motor driver 3, a fan driver 4, a printing unit 5, a lifting mechanism unit 6, a winding motor driver 7, four abutting mechanism units 8, four abutting motor drivers 9, and a control unit 10. The driving device includes the abutting mechanism unit 8, the abutting motor driver 9, and the control unit 10. The conveyance device includes the conveyance unit 2, four abutting mechanism units 8, four abutting motor drivers 9, and the control unit 10.

[0019] The conveyance unit 2 conveys a sheet (corresponding to the conveyed object) P, which is a printing medium fed from a paper feeding unit (not shown). The conveyance unit 2 is disposed below the printing unit 5. As shown in FIGS. 1 and 2, the conveyance unit 2 includes a conveyance belt 21, a driving roller 22, driven rollers 23 to 25, a conveyance motor 26, a platen 27, a platen plate 28, and a suction unit 29.

[0020] The conveyor belt 21 attracts, holds, and transports the paper P that has been transported by the paper feeding unit. The conveyor belt 21 is an annular belt stretched over the drive roller 22 and the driven rollers 23-25. The conveyor belt 21 has numerous belt holes (not shown) which are through holes for air suction. The conveyor belt 21 attracts and holds the paper P on the conveying surface 21a by the suction force generated in the belt holes by the drive of the fan 32 of the suction unit 29, which will be described later. The conveying surface 21a is the surface on which the paper P is placed on the conveyor belt 21, and is the upper surface of the planar portion of the conveyor belt 21 between the drive roller 22 and the driven roller 23. The conveyor belt 21 rotates clockwise (endless movement) in the direction shown in Figure 1, thereby transporting the attracted paper P in the conveying direction from left to right.

[0021] The drive roller 22 rotates the conveyor belt 21.

[0022] The driven rollers 23-25 ​​support the conveyor belt 21 together with the drive roller 22. The driven rollers 23-25 ​​rotate in accordance with the conveyor belt 21. The driven roller 23 is positioned at the same height as the drive roller 22 and to the left of the drive roller 22. The driven rollers 24 and 25 are positioned below the drive roller 22 and the driven roller 23, spaced apart from each other in the left-right direction and at the same height.

[0023] The transport motor 26 rotates the drive roller 22.

[0024] The platen 27 is a flat, plate-like member positioned below the conveyor belt 21 between the drive roller 22 and the driven roller 23, and slidably supports the conveyor belt 21. The platen 27 is rectangular in shape when viewed from above. The platen 27 has multiple through holes to allow air drawn in by the fan 32 to pass through.

[0025] The platen template 28 is a flat, plate-like member positioned below the platen 27 and supporting the platen 27 via several spacers (not shown). The platen template 28 is rectangular in shape when viewed from above. The platen template 28 has several through holes to allow air drawn in by the fan 32 to pass through. The upper surface of the platen template 28 is a flat abutment surface 28a against which the tip (lower end) of the abutment shaft 56 of the abutment mechanism 8, described later, abuts. The platen template 28 is larger than the conveyor belt 21 and the platen 27 in the front-rear direction.

[0026] The suction unit 29 sucks air through the through holes in the plastic template 28, the platen 27, and the belt holes in the conveyor belt 21 to cause the paper P to adhere to the conveyor belt 21. The suction unit 29 comprises a chamber 31 and a fan 32.

[0027] Chamber 31 forms a negative pressure chamber to generate suction force in the belt holes of the conveyor belt 21. Chamber 31 is provided on the back (bottom) side of the plastic template 28.

[0028] The fan 32 exhausts air from the chamber 31. As a result, the fan 32 draws air in through the through holes of the plastic template 28, the plastic template 27, and the belt holes of the conveyor belt 21, generating an adhesive force at the belt holes and causing the paper P to adhere to the conveyor belt 21.

[0029] The transport motor driver 3 drives the transport motor 26.

[0030] Fan driver 4 drives fan 32.

[0031] The printing unit 5 prints on the paper P transported by the transport unit 2. As shown in Figures 1 and 3, the printing unit 5 is equipped with multiple inkjet heads 36 and a head holder 37.

[0032] The inkjet head 36 ejects ink onto the paper P. The inkjet head 36 has a plurality of nozzles (not shown) that open onto the nozzle surface 36a, which is the lower surface facing the transport surface 21a of the transport belt 21, and ejects ink from the nozzles. In this embodiment, 18 inkjet heads 36 are provided, arranged in a staggered pattern.

[0033] The head holder 37 holds the inkjet head 36. The head holder 37 holds the inkjet head 36 by allowing its lower end to protrude downward from its lower surface 37a. The head holder 37 is formed in a rectangular shape when viewed from above.

[0034] The lifting mechanism 6 raises and lowers the conveying unit 2. As shown in Figures 1 and 2, the lifting mechanism 6 includes a wire 41, a winding mechanism 42, and a winding motor 43.

[0035] The wire 41 suspends and supports the conveying section 2. The wire 41 is inserted through a through hole formed in the abutment shaft 56 of each abutment mechanism 8, and its tip (lower end) is connected to the plastic template 28.

[0036] The winding mechanism 42 raises and lowers the conveying unit 2 by winding and unwinding the wire 41.

[0037] The winding motor 43 drives the winding mechanism 42.

[0038] The winding motor driver 7 drives the winding motor 43.

[0039] The stopper mechanism 8 defines the distance H between the head transport surfaces. The distance H between the head transport surfaces is the distance between the nozzle surface 36a of the inkjet head 36 and the transport surface 21a of the transport belt 21. As shown in Figure 3, one stopper mechanism 8 is located at each of the four corners of the head holder 37.

[0040] As shown in Figures 2 and 4, the abutment mechanism 8 comprises an abutment motor 51, an encoder (corresponding to a detection unit) 52, a worm 53, an intermediate gear 54, an abutment gear 55, an abutment shaft (corresponding to a moving body) 56, a nut 57, and a reference block (corresponding to an abutment member) 58.

[0041] The stopper motor 51 rotates the stopper shaft 56 via a worm gear 53, an intermediate gear 54, and a stopper gear 55, thereby moving the stopper shaft 56 vertically. Forward rotation of the stopper motor 51 causes the stopper shaft 56 to rise, and reverse rotation causes the stopper shaft 56 to descend. The stopper motor 51 is a stepping motor.

[0042] The encoder 52 is used to detect step loss in the abutment motor 51. The encoder 52 also detects the direction and amount of movement of the abutment shaft 56. The encoder 52 is mounted on the motor shaft of the abutment motor 51. The encoder 52 consists of a two-phase rotary encoder. The encoder 52 outputs two pulse signals (A-phase signal, B-phase signal) with a predetermined phase difference according to the rotation angle of the motor shaft of the abutment motor 51. Note that the encoder 52 is not shown in Figure 4.

[0043] When the control unit 10 is outputting control pulses to the abutment motor driver 9, the encoder 52 ceasing to output pulse signals indicates that the abutment motor 51 has lost step. Furthermore, the timing relationship between the output pulses of the A-phase signal and the B-phase signal of the encoder 52 indicates the rotation direction of the abutment motor 51 and the movement direction of the abutment shaft 56. In addition, the number of pulses of the A-phase signal and the B-phase signal of the encoder 52 indicates the amount of rotation of the abutment motor 51 and the amount of movement of the abutment shaft 56.

[0044] The worm gear 53 transmits the driving force of the stop motor 51 to the intermediate gear 54. The worm gear 53 is fixed to the motor shaft of the stop motor 51.

[0045] The intermediate gear 54 transmits the driving force of the abutment motor 51 from the worm 53 to the abutment gear 55. The intermediate gear 54 is composed of a two-stage gear consisting of a worm wheel 59 that meshes with the worm 53 and a lower gear 60 which is a spur gear that meshes with the abutment gear 55.

[0046] The abutment gear 55 rotates together with the abutment shaft 56 due to the driving force of the abutment motor 51 transmitted from the intermediate gear 54. The abutment gear 55 is integrally formed with the abutment shaft 56 so as to surround the upper end of the abutment shaft 56. The abutment gear 55 consists of a spur gear that meshes with the lower gear 60.

[0047] The abutment shaft 56 is a component whose lower end abuts against the transport section 2. Specifically, the lower end of the abutment shaft 56 abuts against the abutment surface 28a of the plastic template 28. The abutment shaft 56 is formed by a screw and is screwed into a nut 57. This changes the height position of the abutment shaft 56, which rotates when driven by the abutment motor 51. As a result, the distance H between the head transport surfaces can be changed when the lower end of the abutment shaft 56 abuts against the transport section 2.

[0048] The abutment shaft 56 has a through hole formed in its axial direction, through which the wire 41 is inserted.

[0049] The height position of the abutment shaft 56 of each abutment mechanism 8 can be individually adjusted steplessly by driving each abutment motor 51. Here, the abutment shaft 56 moves up and down by an amount corresponding to the amount of control pulses used to drive the abutment motor 51, but the amount of movement of the abutment shaft 56 for one control pulse is so minute that the height position of the abutment shaft 56 can be considered to be continuously adjustable.

[0050] The nut 57 is used to change the height position of the rotating abutment shaft 56. The nut 57 is fixed to the lower surface 37a of the head holder 37.

[0051] The reference block 58 is the reference position at which the abutment shaft 56 abuts against the reference block 58, which is the reference height position of the abutment shaft 56. When the upper end of the abutment shaft 56 abuts against the reference block 58 and the abutment shaft 56 stops, the abutment shaft 56 is positioned at the reference position.

[0052] The stop motor driver 9 drives the stop motor 51.

[0053] The control unit 10 controls the operation of each part of the inkjet printing device 1. The control unit 10 is composed of a CPU, memory, hard disk, etc.

[0054] The control unit 10 performs reference positioning control to position the abutment shaft 56 at a reference position when the height position of the abutment shaft 56 of each abutment mechanism 8 is unknown, such as when the inkjet printing device 1 is powered on. Specifically, the control unit 10 outputs a control pulse to the abutment motor driver 9 to drive the abutment motor 51 in the forward direction, causing the abutment shaft 56 to abut against the reference block 58 and causing the abutment motor 51 to lose step, thereby positioning the abutment shaft 56 at the reference position.

[0055] In this case, during the reference position setting control, if the stop motor 51 loses step, the encoder 52 detects the stop of step in the stop motor 51. When the stop motor 51 loses step, the control unit 10 starts stopping the control pulse, but there is a time lag between when the stop motor 51 actually loses step and when the control pulse stops.

[0056] Due to the characteristics of a stepping motor, the stop motor 51 may experience phase shift due to vibrations caused by step loss. If the control unit 10 continues to output control pulses while the stop motor 51 is experiencing phase shift, the stop motor 51 may unintentionally reverse direction. As a result, due to the aforementioned time lag, the stop motor 51 may unintentionally reverse direction, causing the stop shaft 56 to unintentionally descend.

[0057] In other words, when the abutment shaft 56 abuts against the reference block 58 and the abutment motor 51 loses step, a step-out reverse movement may occur, which is a downward movement of the abutment shaft 56 (movement in the direction away from the reference block 58). The step-out reverse movement of the abutment shaft 56 and the amount of movement (downward movement) due to this step-out reverse movement are detected by the encoder 52.

[0058] In the reference positioning control, the control unit 10 stores the amount of movement caused by the reverse movement of the stopper shaft 56 during a step loss, when detected by the encoder 52. Then, when the control unit 10 first positions the stopper shaft 56 at the target height after the reference positioning control, it reverses the drive of the stopper motor 51 to move the stopper shaft 56 by a distance equal to the distance between the reference position and the target position minus the amount of movement caused by the reverse movement during the step loss. Here, the target position of the stopper shaft 56 is the height position where the distance H between the head transport surfaces is equal to the target value.

[0059] Next, the operation of positioning the stop shaft 56 at the target position in the inkjet printing device 1 will be explained with reference to the flowcharts in Figures 5 to 8.

[0060] The flowcharts in Figures 5 to 8 describe the processing for one abutment mechanism 8, and the flowcharts in Figures 5 to 8 are performed for each of the four abutment mechanisms 8.

[0061] In step S1 of Figure 5, the control unit 10 determines whether or not it has stored the current height position of the abutment shaft 56.

[0062] Here, if the inkjet printer 1 has not been turned off since the previous operation in which the abutment shaft 56 was positioned at the target position, the control unit 10 stores the height position in which the abutment shaft 56 was positioned in the previous operation as the current height position of the abutment shaft 56. If the inkjet printer 1 has been turned off and then turned on since the previous operation, the control unit 10 does not store the current height position of the abutment shaft 56, and the current height position of the abutment shaft 56 is unknown.

[0063] If the control unit determines that the current height position of the abutment shaft 56 is not stored (step S1: NO), in step S2, the control unit 10 starts raising the abutment shaft 56. This initiates the reference position setting control. Specifically, the control unit 10 outputs a control pulse to the abutment motor driver 9 to start driving the abutment motor 51 in the forward direction.

[0064] Next, in step S3, the control unit 10 determines whether the abutment motor 51 has lost step immediately after the start of the upward control of the abutment shaft 56, that is, immediately after the start of the forward rotation drive control of the abutment motor 51. Here, the control unit 10 determines that the abutment motor 51 has lost step immediately after the start of the upward control of the abutment shaft 56 if a predetermined step-out determination time has elapsed without a pulse signal being input from the encoder 52 after the start of outputting control pulses to the abutment motor driver 9.

[0065] If it is determined that there was no step loss of the stopper motor 51 immediately after the start of the upward control of the stopper shaft 56 (step S3: NO), then in step S4, the control unit 10 determines whether or not the stopper motor 51 has lost step.

[0066] Here, the stopper motor 51 losing step immediately after the start of the upward control of the stopper shaft 56 (immediately after the start of the reference position setting control) occurs when the stopper shaft 56 is in contact with the reference block 58 and positioned at the reference position at the start of the forward rotation drive control of the stopper motor 51, or when there is a malfunction such as a failure of the stopper motor 51. If the stopper motor 51 does not lose step immediately after the start of the upward control of the stopper shaft 56, the stopper shaft 56 is in a position away from the reference block 58 at the start of the forward rotation drive control of the stopper motor 51, as shown in Figure 9(a), and rises from there by the forward rotation drive of the stopper motor 51.

[0067] While the stop motor 51 is driven in the forward direction and the stop shaft 56 is rising, the encoder 52 outputs pulse signals (A-phase signal, B-phase signal), and these pulse signals are input to the control unit 10.

[0068] Then, as shown in Figure 9(b), when the abutment shaft 56 hits the reference block 58, the abutment motor 51 loses step, and the abutment shaft 56 stops at the reference position. In step S4 of Figure 5, it is determined that the abutment motor 51 has lost step when the abutment shaft 56 hits the reference block 58 and loses step.

[0069] Here, the control unit 10 determines that the stop motor 51 has lost step if the time during which no pulse signal is input after the start of input from the encoder 52 reaches a predetermined step-out determination time. If it determines that the stop motor 51 has not lost step (step S4: NO), the control unit 10 repeats step S4.

[0070] If it is determined that the stop motor 51 has lost step (step S4: YES), in step S5, the control unit 10 starts stopping the control pulse.

[0071] Next, in step S6, the control unit 10 determines whether or not a reverse pulse has been input from the encoder 52. Here, the reverse pulse is a pulse of the A-phase signal and B-phase signal whose output timing is reversed compared to when the stop motor 51 is driven in the forward direction. The reverse pulse is counted as one pulse when it consists of one pulse of the A-phase signal and one pulse of the B-phase signal.

[0072] Here, even if the control pulse stop control is initiated in step S5 described above, it cannot stop immediately, and the control pulse continues to be output for a while. Therefore, as mentioned above, a time lag occurs between the actual loss of synchronism of the abutment motor 51 and the stopping of the control pulse. Due to this time lag, the abutment motor 51 may unintentionally reverse direction, and the abutment shaft 56 may unintentionally descend. When the abutment motor 51 reverses direction, a reverse pulse is output from the encoder 52, and this reverse pulse is input to the control unit 10.

[0073] Figure 10 shows an example of the control pulse, A-phase signal, and B-phase signal of the encoder 52 when reverse rotation occurs due to step loss of the stop motor 51. As shown in Figure 10, even if the stop motor 51 loses step, the control pulse is not stopped at time t1. Then, in the example in Figure 10, the stop motor 51 unintentionally reverses from time t2, and a reverse pulse is output from time t2 until time t3, when the reverse rotation of the stop motor 51 and the resulting descent of the stop shaft 56 (reverse movement during step loss) stop.

[0074] Returning to Figure 5, if in step S6 it is determined that one reverse pulse has been input (step S6: YES), in step S7 the control unit 10 adds "1" to the reverse pulse count value C. After this, the control unit 10 proceeds to step S8.

[0075] If the control unit 10 determines in step S6 that no reversal pulse has been input (step S6: NO), it skips step S7 and proceeds to step S8.

[0076] In step S8, the control unit 10 determines whether or not the abutment shaft 56 has stopped. Here, the control unit 10 determines that the abutment shaft 56 has stopped if the time since the last reverse pulse was input (or since it was determined in step S4 that the abutment motor 51 had lost step if no reverse pulse was input) has reached a predetermined stop determination time. If it is determined that the abutment shaft 56 has not stopped (step S8: NO), the control unit 10 returns to step S6.

[0077] At this point, the value of the count C stored in the control unit 10 when it determines that the stop shaft 56 has stopped indicates the amount of movement due to the reverse movement during a step out. In other words, the control unit 10 stores the amount of movement due to the reverse movement during a step out.

[0078] If reverse movement occurs during a step-out, the abutment shaft 56 stops at a position lower than the reference block 58, as shown in Figure 9(c). If reverse movement does not occur during a step-out, the abutment shaft 56 remains stopped at the reference position while in contact with the reference block 58, as shown in Figure 9(b).

[0079] Returning to Figure 5, if it is determined in step S8 that the abutment shaft 56 has stopped (step S8: YES), then in step S9, the control unit 10 calculates the amount of control pulses required to move the abutment shaft 56 from the reference position to the target position.

[0080] At this point, the reference position setting control ends in step S8 described above, and in step S9, the process of first positioning the abutment shaft 56 at the target position after the reference position setting control begins.

[0081] Next, in step S10 of Figure 6, the control unit 10 determines whether or not the count value C = 0.

[0082] If it is determined that the count value C is not 0 (step S10: NO), in step S11, the control unit 10 corrects the control pulse amount calculated in step S9.

[0083] Specifically, the control unit 10 converts the count value C into a pulse amount required to move the shaft by the distance indicated by that value (the amount of movement due to reverse movement during step loss). Then, the control unit 10 subtracts the pulse amount converted from the count value C from the control pulse amount calculated in step S9. The corrected control pulse amount is the pulse amount required to move the stop shaft 56 by the distance obtained by subtracting the amount of movement due to reverse movement during step loss from the distance between the reference position and the target position.

[0084] Next, in step S12, the control unit 10 resets the count value C to 0. After this, the control unit 10 proceeds to step S13.

[0085] If the control unit 10 determines in step S10 that the count value C = 0 (step S10: YES), it skips steps S11 and S12 and proceeds to step S13.

[0086] In step S13, the control unit 10 lowers the abutment shaft 56 to the target position. Specifically, the control unit 10 outputs a control pulse to the abutment motor driver 9 to drive the abutment motor 51 in reverse. If the control unit 10 determines in step S10 that the count value C = 0 (step S10: YES), it outputs a control pulse of the control pulse amount calculated in step S9. If the control unit 10 determines in step S10 that the count value C is not 0 (step S10: NO), it outputs a control pulse of the control pulse amount corrected in step S11. As a result, the abutment shaft 56 lowers to the target position and stops, as shown in Figure 9(d).

[0087] Returning to Figure 6, in step S14, the control unit 10 stores the position (target position) where the abutment shaft 56 was positioned by the processing in step S13 as the current height position of the abutment shaft 56. This completes the series of operations.

[0088] In step S3 of Figure 5, if the control unit 10 determines that the stop motor 51 has lost step immediately after the start of the upward control of the stop shaft 56 (step S3: YES), the control unit 10 proceeds to step S15 of Figure 7. The processing in steps S15 to S18 is the same as the processing in steps S5 to S8 of Figure 5 described above.

[0089] As mentioned above, the stopper motor 51 loses step immediately after the start of the upward control of the stopper shaft 56 (immediately after the start of the reference position setting control) if the stopper shaft 56 was in contact with the reference block 58 and positioned at the reference position at the start of the forward rotation drive control of the stopper motor 51, or if there is a malfunction such as a failure of the stopper motor 51. If the stopper shaft 56 was in contact with the reference block 58 at the start of the forward rotation drive control of the stopper motor 51, a reverse movement due to the stopper motor 51 losing step may occur. If a reverse movement due to the stopper occurs, the value of the count C, which indicates the amount of movement due to the reverse movement due to the stopper, is stored in the control unit 10 by the processing in steps S16 to S18.

[0090] If, in step S18, it is determined that the abutment shaft 56 has stopped (step S18: YES), then in step S19, the control unit 10 calculates the amount of control pulses necessary to move the abutment shaft 56 from the reference position to a preset designated position.

[0091] Next, in step S20 of Figure 8, the control unit 10 determines whether or not the count value C = 0.

[0092] If it is determined that the count value C is not 0 (step S20: NO), in step S21, the control unit 10 corrects the control pulse amount calculated in step S19. The process of correcting the control pulse amount calculated in step S19 in step S21 is the same as the process of correcting the control pulse amount calculated in step S9 in step S11 described above.

[0093] Next, in step S22, the control unit 10 resets the count value C to 0. After this, the control unit 10 proceeds to step S23.

[0094] If the control unit 10 determines in step S20 that the count value C = 0 (step S20: YES), it skips steps S21 and S22 and proceeds to step S23.

[0095] In step S23, the control unit 10 reverses the drive of the abutment motor 51 by the amount of control pulses calculated in step S19 or the corrected control pulse amount in step S21, thereby lowering the abutment shaft 56.

[0096] If step S20 determines that the count value C = 0 (step S20: YES), then in step S23, the control unit 10 outputs a control pulse of the control pulse amount calculated in step S19 to the stop motor driver 9. If step S20 determines that the count value C is not 0 (step S20: NO), then in step S23, the control unit 10 outputs a control pulse of the corrected control pulse amount from step S21 to the stop motor driver 9.

[0097] Here, if the abutment shaft 56 is in contact with the reference block 58 and positioned at the reference position at the start of the forward rotation drive control of the abutment motor 51 in step S2 of Figure 5 (the start of the reference position setting control), then the abutment shaft 56 will descend to the specified position and stop according to the process in step S23 of Figure 8 described above.

[0098] Next, in step S24, the control unit 10 starts raising the abutment shaft 56 by driving the abutment motor 51 in the forward direction until the abutment motor 51 loses step. After this, the control unit 10 proceeds to step S25. The processing in steps S25 to S29 is the same as the processing in steps S4 to S8 in Figure 5 described above.

[0099] If there are no malfunctions such as failure of the stop motor 51, in step S24 the forward rotation drive of the stop motor 51 is started, and then the stop shaft 56 hits the reference block 58 and the stop motor 51 loses step. If this loss of step causes reverse movement during the loss of step, the control unit 10 stores a count value C, which indicates the amount of movement due to the reverse movement during the loss of step, in steps S27 to S29.

[0100] Next, in step S30, the control unit 10 determines whether the downward amount La and the upward amount Lb are equal.

[0101] Here, the downward amount La is the amount of downward movement of the abutment shaft 56 from the moment of step loss immediately after the start of forward rotation control of the abutment motor 51 in step S2 (immediately after the start of reference position setting control) until the end of reverse rotation drive of the abutment motor 51 in step S23. If a step loss occurs immediately after the start of forward rotation control of the abutment motor 51 in step S2, resulting in reverse movement during step loss, the downward amount La includes the amount of movement (downward movement) due to that reverse movement during step loss. In other words, the downward amount La is the same as the distance from the reference position to the specified position.

[0102] The rise amount Lb is the amount of rise of the abutment shaft 56 from the start of forward rotation of the abutment motor 51 in step S24 until the abutment motor 51 loses step. The control unit 10 can calculate the rise amount Lb from the amount of control pulses during that period.

[0103] Here, Figure 11 shows an example of the control pulse, A-phase signal and B-phase signal of the encoder 52 when the stop motor 51 loses step immediately after the start of the forward rotation drive control of the stop motor 51 in step S2 (immediately after the start of the reference position setting control).

[0104] In Figure 11, even though the output of the control pulse starts at time t11 (step S2 in Figure 5), the A-phase signal pulse and the B-phase signal pulse of the encoder 52 are not output. Therefore, it is determined that the stop motor 51 has lost step immediately after the start of forward rotation drive control (step S3 in Figure 5: YES), and the control pulse is stopped at time t12. In the example in Figure 11, there is no reverse rotation due to the stop motor 51 losing step, nor is there any downward movement of the stop shaft 56 (reverse movement during step loss).

[0105] Subsequently, at times t13-t14, the abutment motor 51 is driven in reverse, and the abutment shaft 56 descends by the same amount as the distance from the reference position to the specified position (downward amount La) (step S23 in Figure 8).

[0106] Subsequently, at time t15, the forward rotation of the stop motor 51 begins, and the upward movement of the stop shaft 56 begins (step S24 in Figure 8). Then, at time t16, the stop motor 51 loses step (step S25: YES in Figure 8), causing the stop shaft 56 to stop.

[0107] In this case, assuming there is no malfunction such as failure of the stopper motor 51, and the step loss of the stopper motor 51 immediately after the start of the reference position setting control is due to the stopper shaft 56 being in contact with the reference block 58 and positioned at the reference position at the start of the reference position setting control, the stopper shaft 56 will descend from the reference position to the specified position by the downward control at times t13 to t14.

[0108] Furthermore, if a step-out and reverse movement occurs due to a step-out of the stop motor 51 immediately after the start of the reference position setting control, the stop shaft 56 will descend in the downward control at times t13 to t14 by the amount of the corrected control pulse amount in step S21 of Figure 8 described above, thereby descending from the position after the step-out and reverse movement to the specified position.

[0109] Then, the abutment axis 56 begins to rise from the designated position at time t15, and then at time t16, it abuts against the reference block 58 and stops at the reference position. Therefore, the amount of rise Lb from time t15 to t16 is equal to the amount of fall La.

[0110] Therefore, in the inkjet printing device 1, if the downward amount La and the upward amount Lb are equal, the control unit 10 determines that the abutment shaft 56 was in contact with the reference block 58 and positioned at the reference position at the start of the reference position setting control. If the downward amount La and the upward amount Lb are not equal, the control unit 10 determines that there is a malfunction such as a failure of the abutment motor 51.

[0111] Returning to Figure 8, if in step S30 it is determined that the downward amount La and the upward amount Lb are equal (step S30: YES), then in step S31 the control unit 10 determines that the abutment shaft 56 was positioned at the reference position at the start of the reference position setting control. After this, the control unit 10 proceeds to step S9 in Figure 5, and through the processing in steps S9 to S13, positions the abutment shaft 56 at the target position.

[0112] In step S30 of Figure 8, if it is determined that the downward amount La and the upward amount Lb are not equal (step S30: NO), in step S32, the control unit 10 determines that there is a malfunction such as a failure of the stop motor 51 and terminates the series of processes. After this, the control unit 10 displays a message on the display unit (not shown) prompting a service technician to inspect the unit.

[0113] In step S1 of Figure 5, if it is determined that the current height position of the abutment shaft 56 is stored (step S1: YES), then in step S33, the control unit 10 calculates the amount of control pulses required to move the abutment shaft 56 from its current height position to the target position.

[0114] Next, in step S34, the control unit 10 moves the abutment shaft 56 to the target position. Specifically, the control unit 10 outputs a control pulse of the control pulse amount calculated in step S33 to the abutment motor driver 9, causing the abutment motor 51 to rotate in either the forward or reverse direction until the abutment shaft 56 reaches the target position.

[0115] After this, the control unit 10 proceeds to step S14 in Figure 6, and stores the position where the abutment shaft 56 is positioned (target position) as the current height position of the abutment shaft 56, as processed in step S34. This completes the series of operations.

[0116] When each abutment shaft 56 is positioned at the target location through the flowchart processing shown in Figures 5 to 8 for each abutment mechanism 8, the control unit 10 raises the transport unit 2 using the lifting mechanism 6, causing the abutment shaft 56 to abut against the plastic template 28, as shown in Figure 9(e). As a result, the distance H between the head transport surfaces becomes the target value.

[0117] In this way, when transporting paper P, the transport unit 2 is positioned so that the four abutment shafts 56 located at the target position abut against the platen 28. In this state, the platen 28 and the platen 27 are parallel to the nozzle surface 36a and the lower surface 37a of the head holder 37.

[0118] As explained above, in the inkjet printing apparatus 1, when the control unit 10 detects the reverse movement of the stopper shaft 56 during a step loss and the amount of movement caused by that reverse movement during a step loss during reference positioning control, it stores the amount of movement caused by the reverse movement during a step loss. Then, when the control unit 10 first positions the stopper shaft 56 at the target position after reference positioning control, it drives the stopper motor 51 in reverse to move the stopper shaft 56 by a distance obtained by subtracting the amount of movement caused by the reverse movement during a step loss from the distance between the reference position and the target position. As a result, even if the stopper shaft 56 moves in a reverse direction due to a step loss in the stopper motor 51, the amount of movement of the stopper shaft 56 when positioning the stopper shaft 56 at the target position can be corrected using the amount of movement caused by the reverse movement during a step loss, thereby reducing the deviation of the stopper shaft 56 from the target position.

[0119] Furthermore, as described above, the inkjet printing apparatus 1 can reduce the deviation of the stopper shaft 56 from the target position, thereby suppressing variations in the height position of each stopper shaft 56. This allows for suppression of the tilt of the transport unit 2. As a result, the tilt of the transport surface 21a can be suppressed, making it possible to adjust the head gap (the distance between the nozzle surface 36a and the paper P on the transport surface 21a) to an appropriate level across the entire printing area of ​​the paper P.

[0120] If there is variation in the height of each abutment shaft 56, when each abutment shaft 56 is brought into contact with the plastic template 28, twisting may occur in the conveying section 2. As a result, the conveying belt 21 may shift to one side in the front-rear direction. When belt shifting occurs, there is a risk of damage to the conveying belt 21 due to buckling, etc. In contrast, in the inkjet printing apparatus 1, as described above, the deviation of the abutment shaft 56 from the target position can be reduced, so variation in the height of each abutment shaft 56 can be suppressed. Therefore, damage to the conveying belt 21 due to belt shifting can be reduced.

[0121] Furthermore, in the inkjet printing apparatus 1, if the abutment motor 51 loses step in the reference position setting control immediately after the start of forward rotation drive control of the abutment motor 51, the control unit 10 lowers the abutment shaft 56 and then raises the abutment shaft 56 until the abutment motor 51 loses step. Then, based on the amount of lowering La and the amount of raising Lb of the abutment shaft 56 described above, the control unit 10 determines whether the abutment shaft 56 was positioned in the reference position at the start of the reference position setting control. This makes it possible to determine whether the abutment motor 51 lost step immediately after the start of the reference position setting control because the abutment shaft 56 was positioned in the reference position at the start of the reference position setting control, or whether the abutment shaft 56 lost step due to a malfunction such as a failure of the abutment motor 51.

[0122] In the above-described embodiment, the inkjet printing apparatus 1 was described as having four stopper mechanisms 8, one at each of the four corners of the head holder 37. However, the number of stopper mechanisms 8 is not limited to this. Any configuration that includes three or more stopper mechanisms 8, where the stopper shafts 56 abut against the stopper surface 28a of the plastic template 28 at three or more positions that are not on the same straight line, is acceptable, so that the stopper surface 28a becomes a plane defined by the points of the tips of each stopper shaft 56.

[0123] Furthermore, although the above-described embodiment described the stop mechanism 8 of the inkjet printing apparatus 1, the present invention is not limited to this and can be applied to any drive device that moves a moving body using a stepping motor.

[0124] The present invention is not limited to the embodiments described above, and the components can be modified and implemented in practice without departing from the spirit of the invention. Furthermore, various inventions can be formed by appropriately combining the multiple components disclosed in the embodiments. For example, some components may be deleted from all the components shown in the embodiments.

[0125] [Note] This application discloses the following invention:

[0126] (Note 1) Stepping motor and A moving body that moves by the drive of the stepping motor, A detection unit for detecting the direction and amount of movement of the moving body, A stopper member against which the moving body abuts at the reference position of the moving body, The system includes a control unit that performs reference positioning control to position the moving body at a reference position by driving the stepping motor in the forward direction to abut the moving body against the abutment member and causing the stepping motor to lose step, The control unit, In the aforementioned reference positioning control, when the detection unit detects the movement of the moving body away from the abutment member due to the stepping motor losing step, and the amount of movement due to the stepping motor losing step, the amount of movement due to the stepping motor losing step is stored. A drive device characterized in that, when the moving body is first positioned at the target position after the reference position setting control, the stepping motor is driven in reverse to move the moving body by a distance obtained by subtracting the amount of movement due to the reverse movement during step loss from the distance between the reference position and the target position.

[0127] (Note 2) The control unit, In the aforementioned reference positioning control, if the stepping motor loses step immediately after the start of forward rotation control of the stepping motor, the stepping motor is driven in reverse to move the moving body away from the abutment member, and then the stepping motor is driven in forward until it loses step, moving the moving body towards the abutment member. The drive device according to Appendix 1, characterized in that it determines whether the moving body was positioned at the reference position at the start of the reference position setting control, based on the amount of movement of the moving body away from the abutment member during the period from the start of the forward rotation drive control of the stepping motor in the reference position setting control until the end of the reverse rotation drive of the stepping motor, which includes the amount of movement due to the reverse rotation movement during stepping out and the amount of movement due to the reverse rotation movement during stepping out if the amount of movement due to the reverse rotation movement during stepping out is detected by the detection unit, and the amount of movement of the moving body in the direction approaching the abutment member when the moving body is moved away from the abutment member and then driven in the forward rotation until the stepping motor is driven out of stepping to move the moving body towards the abutment member.

[0128] (Note 3) A drive device according to Appendix 1 or 2, having three or more of the stepping motor, the moving body, the detection unit, and the abutment member, The moving body has a flat abutment surface against which it strikes, and the system includes a conveying unit for conveying an object to be conveyed, When transporting an object to be transported, the transport unit is configured such that three or more of the moving bodies positioned at the target location abut against the abutment surface. A conveying device characterized in that three or more of the moving bodies abut against the abutment surface at three or more positions that are not on the same straight line. [Explanation of symbols]

[0129] 1. Inkjet printing device 2. Conveying section 3. Transport motor driver 4 Fan Drivers 5 Printing Department 6. Lifting mechanism 7. Rewinding motor driver 8 Abutment mechanism section 9. Push-button motor driver 10 Control Unit 21 Conveyor belt 21a Conveying surface 22 drive rollers 23-25 ​​Driven roller 26. Transport motor 27 Platen 28 Plastic Templates 28a Immediately 29 Suction part 31 Chambers 32 Fans 36 Inkjet Heads 36a Nozzle surface 37 Head holder 41 wires 42 Winding mechanism section 43 Rewinding motor 51. Butt motor 52 encoders 53 Warm 54 intermediate gear 55 Charge Gear 56 Assault axis 57 Nut 58 Reference Blocks 59 Worm Wheel 60 Lower gear

Claims

1. Stepping motor and A moving body that moves by the drive of the stepping motor, A detection unit for detecting the direction and amount of movement of the moving body, A stopper member against which the moving body abuts at the reference position of the moving body, The system includes a control unit that performs reference positioning control to position the moving body at a reference position by driving the stepping motor in the forward direction to abut the moving body against the abutment member and causing the stepping motor to lose step, The control unit, In the aforementioned reference positioning control, when the detection unit detects the movement of the moving body away from the abutment member due to the stepping motor losing step, and the amount of movement due to the stepping motor losing step, the amount of movement due to the stepping motor losing step is stored. A drive device characterized in that, when the moving body is first positioned at the target position after the reference position setting control, the stepping motor is driven in reverse to move the moving body by a distance obtained by subtracting the amount of movement due to the reverse movement during step loss from the distance between the reference position and the target position.

2. The control unit, In the aforementioned reference positioning control, if the stepping motor loses step immediately after the start of forward rotation control of the stepping motor, the stepping motor is driven in reverse to move the moving body away from the abutment member, and then the stepping motor is driven in forward until it loses step, moving the moving body towards the abutment member. The drive device according to claim 1, characterized in that it determines whether the moving body was positioned at the reference position at the start of the reference position setting control, based on the amount of movement of the moving body away from the abutment member during the period from the start of the forward rotation drive control of the stepping motor in the reference position setting control until the end of the reverse rotation drive of the stepping motor, which includes the amount of movement due to the reverse rotation movement during stepping out and, if the amount of movement due to the reverse rotation movement during stepping out is detected by the detection unit, and the amount of movement of the moving body in the direction approaching the abutment member when the moving body is moved away from the abutment member and then driven in the forward rotation until the stepping motor is driven out of stepping to move the moving body towards the abutment member, and the amount of movement of the moving body in the direction approaching the abutment member at the start of the reference position setting control.

3. A drive device according to claim 1 or 2, comprising three or more of the stepping motor, the moving body, the detection unit, and the abutment member, The moving body has a flat abutment surface against which it strikes, and the system includes a conveying unit for conveying an object to be conveyed, When transporting an object to be transported, the transport unit is configured such that three or more of the moving bodies positioned at the target location abut against the abutment surface. A conveying device characterized in that three or more of the moving bodies abut against the abutment surface at three or more positions that are not on the same straight line.

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