Detection system and inkjet recording apparatus

Abstract

To suppress deterioration of detection accuracy due to backlash of a gear train.SOLUTION: A detection system includes a detection target device including a first rotary member that rotates around a first axis, a detection device including a second rotary member that rotates around a second axis by a driving force transmitted from the first rotary member via a gear train, an output value of the detection device monotonically increasing or monotonically decreasing according to a rotation angle of the second rotary member, and a control unit that calculates a driving amount of the first rotary member for correcting the output value of the detection device from a phase shift of the output value of the detection device when a rotation direction of the first rotary member is changed.SELECTED DRAWING: Figure 16

Description

[Technical Field]

[0001] The present invention relates to a detection system and an inkjet recording apparatus. [Background technology]

[0002] To obtain good image quality in an inkjet recording apparatus, it is necessary to optimize the gap between the conveyed sheet and the inkjet head. Therefore, technologies for adjusting the gap depending on the thickness of the sheet have been studied. For example, Patent Documents 1 and 2 disclose configurations in which the position of the sheet is detected by a sensor and the distance between the sheet and the head is adjusted based on the sheet position. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-142994 [Patent Document 2] Japanese Patent Application Laid-Open No. 2017-177431 Summary of the Invention [Problem to be solved by the invention]

[0004] One possible means for adjusting the gap is to support the inkjet head via a stepped member that accommodates various sheet thicknesses and then slide the stepped member to change the height of the inkjet head. In this case, checking the amount of movement of the stepped member ensures that the gap is appropriate, but to accommodate sheets of various thicknesses, it is necessary to improve the accuracy of detecting the amount of movement. For example, in a configuration in which the amount of movement is detected from a rotatable stepped member via a gear train, there is a problem of reduced detection accuracy due to backlash in the gear train.

[0005] In consideration of the above circumstances, the present invention aims to suppress a decrease in detection accuracy due to backlash in a gear train. [Means for solving the problem]

[0006] In order to solve the above problem, the detection system of the present invention comprises a detection target device having a first rotating member that rotates around a first axis, a detection device having a second rotating member that rotates around a second axis by a driving force transmitted from the first rotating member via a gear train, and an output value that monotonically increases or monotonically decreases depending on the rotation angle of the second rotating member, and a control unit that calculates the driving amount of the first rotating member to correct the output value of the detection device from the phase shift of the output value of the detection device when the rotation direction of the first rotating member is changed.

[0007] The control unit may calculate the amount of drive of the first rotating member to correct the output value of the detection device based on the phase shift of the output value of the detection device when the rotation direction of the first rotating member is changed and the proportional relationship between the amount of drive of the first rotating member and the output value of the detection device.

[0008] The first rotating member has an intersecting surface that intersects with the first axis, and the device to be detected has a stair portion provided on the intersecting surface and whose height changes stepwise in the circumferential direction, an adjustment member facing the intersecting surface and movable in the first axial direction, and a sphere sandwiched between the adjustment member and the intersecting surface and whose movement in the circumferential direction is restricted, or a protrusion protruding from the adjustment member and contacting the intersecting surface, wherein the stair portions of the same pattern are provided at N locations (N is an integer of 2 or greater) around the circumferential direction of the intersecting surface, one sphere or one protrusion is arranged on each of the N stair portions, and the sphere or the protrusion may contact steps of the same height at the N stair portions.

[0009] the detection target device repeats an operation according to the rotation angle of the first rotating member every time the first rotating member makes 1 / N rotation, The output value of the detection device may repeat a monotonous increase or decrease according to the rotation angle of the second rotating member every time the second rotating member makes one rotation.

[0010] The sensing device may be a potentiometer.

[0011] The first rotating member and the second rotating member may be gears.

[0012] Moreover, the inkjet recording apparatus according to the present invention is characterized in that it comprises a head unit having one or more inkjet heads and contacting the adjustment member, and the detection system, and the control unit controls the detection target device in accordance with the amount of operation of the detection target device detected by the detection system. [Effects of the Invention]

[0013] According to the present invention, it is possible to suppress a decrease in detection accuracy due to backlash in the gear train. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a perspective view showing the appearance of an image forming system according to an embodiment of the present invention; [Figure 2] 1 is a front view schematically illustrating the internal configuration of an inkjet recording apparatus according to an embodiment of the present invention. [Figure 3] FIG. 1 is a perspective view showing a head unit according to an embodiment of the present invention. [Figure 4] FIG. 1 is a perspective view showing a head unit according to an embodiment of the present invention. [Figure 5] 1 is a perspective view showing an adjustment device according to an embodiment of the present invention. [Figure 6] FIG. 1 is a perspective view showing a gap adjustment device according to an embodiment of the present invention. [Figure 7] 2 is a perspective view showing a first rotating member, a ball, and a cage according to one embodiment of the present invention. FIG. [Figure 8] FIG. 2 is a perspective view showing a first rotating member and a sphere according to an embodiment of the present invention. [Figure 9] FIG. 2 is a perspective view showing a first rotating member according to one embodiment of the present invention. [Figure 10]FIG. 7 is a cross-sectional view showing cross section II of FIG. 6. [Figure 11] FIG. 2 is a plan view showing a first rotating member according to one embodiment of the present invention. [Figure 12] FIG. 12 is a cross-sectional view showing the II-II cross section of FIG. [Figure 13] 1 is a perspective view illustrating a detection system according to an embodiment of the present invention. [Figure 14] 10A and 10B are diagrams illustrating the operation of the detection system during one rotation of the first rotating member. [Figure 15] 10 is a diagram showing the operation of the detection system while the first rotating member makes one Nth rotation (N=3). FIG. [Figure 16] 10 is a diagram showing a phase shift caused by backlash when the rotation direction of the first rotating member is changed. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0015] A detection system 200 and an inkjet recording apparatus 1 according to an embodiment of the present invention will be described below with reference to the drawings.

[0016] FIG. 1 is a perspective view showing the appearance of an image forming system 100. FIG. 2 is a front view schematically showing the internal configuration of an inkjet recording apparatus 1. FIGS. 3 and 4 are perspective views showing a head unit 11. In the following description, the front side of the paper in FIG. 2 is the front side (front side) of the inkjet recording apparatus 1, and the left and right directions are described based on the direction when the inkjet recording apparatus 1 is viewed from the front. In each figure, U, Lo, L, R, Fr, and Rr represent up, down, left, right, front, and rear, respectively.

[0017] The image forming system 100 (see FIG. 1) includes a paper feeder 110, an inkjet recording device 1, a drying device 120, and a post-processing device 130. The paper feeder 110 stores several thousand sheets and supplies the sheets to the inkjet recording device 1. The inkjet recording device 1 forms an image on the sheets using an inkjet method. The drying device 120 heats and dries the ink ejected onto the sheets. The post-processing device 130 performs post-processing on the sheets, such as punching, stapling, and folding.

[0018] The inkjet recording device 1 (see FIG. 2) includes a rectangular parallelepiped main housing 3. A transport unit 7 that adsorbs and transports a sheet in the Y direction is provided in the center of the main housing 3. An imaging unit 6 that ejects ink to form an image is provided above the transport unit 7. A paper feed opening 8 that introduces a sheet from a paper feed device 110 is provided on the right side of the main housing 3. A discharge opening 9 that discharges the sheet on which an image has been formed to a drying device 120 is provided on the left side of the main housing 3. A transport path 10 is provided inside the main housing 3, extending from the paper feed opening 8 through the gap between the transport unit 7 and the imaging unit 6 to the discharge opening 9. A registration roller 18 is provided upstream of the transport unit 7 in the transport direction Y.

[0019] The transport unit 7 includes an endless transport belt 21 and a suction unit 24. The transport belt 21 has a number of air holes (not shown) and is wound around a drive roller 25 and a driven roller 22. The upper surface of the suction unit 24 has a number of air holes (not shown) and is in contact with the inner surface of the transport belt 21. The suction unit 24 sucks air through the air holes of the transport belt 21 and the suction unit 24, thereby adsorbing the sheet to the transport belt 21. The drive roller 25 is driven counterclockwise by a drive unit (not shown) including a motor and a reduction gear, causing the transport belt 21 to rotate counterclockwise, and the sheet adsorbed to the transport belt 21 is transported.

[0020] The imaging unit 6 includes a plurality of head units 11 (four in this embodiment). Each head unit 11 (see FIGS. 3 and 4) includes one or more inkjet heads 12 (three inkjet heads 12 arranged in a staggered pattern in this embodiment). Each of the four head units 11 is connected to an ink container 20 filled with black, cyan, magenta, or yellow ink. A maintenance device 30 for performing maintenance on the inkjet head 12 is provided to the right of each head unit 11.

[0021] The control unit 2 (see FIG. 2) includes a calculation unit and a storage unit (not shown). The calculation unit is, for example, a CPU (Central Processing Unit). The storage unit includes storage media such as a ROM (Read Only Memory), a RAM (Random Access Memory), and an EEPROM (Electrically Erasable Programmable Read Only Memory). The calculation unit performs various processes by reading and executing control programs stored in the storage unit. Note that the control unit 2 may be realized by an integrated circuit that does not use software.

[0022] A display operation unit 19 is provided on the top of the main body housing 3 (see FIGS. 1 and 2). The display operation unit 19 includes a display panel, a touch panel stacked on the display panel, and a keypad (not shown). The control unit 2 displays a screen showing the operation menu and status of the inkjet recording device 1 on the display panel, and controls each part of the inkjet recording device 1 in response to operations detected by the touch panel and the keypad.

[0023] The basic image formation operation of the inkjet recording apparatus 1 is as follows. When an image formation job is input to the inkjet recording apparatus 1 from the display operation unit 19, an external computer, or the like, the paper feeder 110 feeds a sheet into the conveyance path 10 through the paper feed port 8, and the registration rollers 18, whose rotation has been stopped, correct any skew in the sheet. When the registration rollers 18 feed the sheet to the conveyance unit 7 at a predetermined timing, the conveyance unit 7 absorbs the sheet onto the conveyance belt 21 and conveys it in the Y direction. Ink is ejected from the nozzles onto the sheet, forming an image. The sheet with the image formed on it is discharged to the drying device 120 through the discharge port 9.

[0024] [Adjustment device] The rear end and front end of the head unit 11 are supported by adjustment devices 40 and 60, respectively (see FIGS. 3 and 4). The adjustment devices 40 and 60 have the function of adjusting the position of the head unit 11 in the up-down direction.

[0025] FIG. 5 is a perspective view showing the adjustment device 40. FIG. 6 is a perspective view showing the gap adjustment device 50. FIG. 7 is a perspective view showing the first rotating member 51, the sphere 52B, and the holder 53. FIG. 8 is a perspective view showing the first rotating member 51 and the sphere 52B. FIG. 9 is a perspective view showing the first rotating member 51. FIG. 10 is a cross-sectional view showing the II cross section of FIG. 6. FIG. 11 is a plan view showing the first rotating member 51. FIG. 12 is a cross-sectional view showing the II-II cross section of FIG. 11. FIG. 13 is a perspective view showing the detection system 200.

[0026] The head unit 11 (see FIGS. 3 and 4) includes three inkjet heads 12 arranged in a staggered pattern and a frame 11F that supports the three inkjet heads 12. Contact portions 11C are provided at two locations in the left and right directions on both the front and rear ends of the bottom of the frame 11F. The contact portions 11C are, for example, pins that protrude downward. An adjustment device 40 is provided below the rear end of the frame 11F. An adjustment device 60 is provided below the front end of the frame 11F. The adjustment devices 40 and 60 support the head unit 11 via the contact portions 11C. The adjustment device 40 will be described below as an example.

[0027] The adjustment device 40 (see FIG. 5) has a rectangular parallelepiped housing 41 with the longitudinal direction in the left-right direction. Gap adjustment devices 50 (see FIG. 6) are housed inside the housing 41. The gap adjustment devices 50 are provided in two locations in the left-right direction. The right gap adjustment device 501 and the left gap adjustment device 502 have the same basic configuration.

[0028] [Gap adjustment device] The gap adjustment device 50 (see FIGS. 6 to 12) includes a first shaft 51A, a first rotating member 51, an adjustment member 54, a spherical body 52B, and a retainer 53.

[0029] [First shaft, first rotating member] The first shaft 51A is supported by the housing 41 with its axial direction extending in the vertical direction. The first rotating member 51 is, for example, a spur gear with 45 teeth. The upper surface of the first rotating member 51 (see FIGS. 9, 11, and 12) is an example of an intersecting surface 51C that intersects with the first shaft 51A. The intersecting surface 51C is provided with staircase portions 51S whose height changes stepwise in the circumferential direction. The staircase portions 51S of the same pattern are provided at multiple locations around the circumferential direction of the intersecting surface 51C. In this embodiment, the staircase portions 51S of the same pattern are provided at three locations around the circumferential direction of the intersecting surface 51C.

[0030] [Stairs section] The staircase portion 51S has five steps 51H arranged in the circumferential direction and four slopes 51G connecting two adjacent steps 51H. The five steps 51H are provided so that their height increases stepwise in a counterclockwise direction. If the height of the lowest step 51H is 0.0 mm (see FIG. 12), the height of the step 51H increases by 0.2 mm for each step in the counterclockwise direction. The three staircase portions 51S are provided at equal intervals in the circumferential direction. In other words, the intersecting surfaces 51C are configured so that the same pattern of step-like height changes is repeated at 120° intervals.

[0031] [Adjustment parts] The adjustment member 54 (see FIGS. 6 and 10) is formed in the shape of a rectangular parallelepiped block as a whole. The adjustment member 54 is provided above the first rotation member 51. One surface 541 (e.g., the lower surface) of the adjustment member 54 faces the intersecting surface 51C of the first rotation member 51, and the other surface 542 (e.g., the upper surface) of the adjustment member 54 faces the bottom of the frame 11F (see FIGS. 3 and 4). The adjustment member 54 is supported by the housing 41 and the first shaft 51A, and is slidable in the direction of the first shaft 51A.

[0032] [sphere] Spheres 52B (see FIGS. 7, 8, and 10) are provided between one surface 541 of adjustment member 54 and intersecting surface 51C. One sphere 52B is arranged in each of the plurality of staircase portions 51S. Three spheres 52B are arranged at 120° intervals. That is, spheres 52B contact steps 51H of the same height in the plurality of staircase portions 51S. Spheres 52B are held by retainer 53. Retainer 53 restricts relative movement of spheres 52B with respect to retainer 53. Parts of spheres 52B protrude from the upper and lower surfaces of retainer 53. Retainer 53 is supported by housing 41 and first shaft 51A and is slidable in the direction of first shaft 51A but is restricted from rotating about first shaft 51A. This configuration restricts circumferential movement of spheres 52B. As the first rotating member 51 rotates, the height of the step 51H that contacts the sphere 52B changes, and the adjustment member 54 moves together with the sphere 52B and the retainer 53 in the direction of the first axis 51A.

[0033] [Regulation Department] The top of the gap adjustment device 50 is covered with a lid 42 (see FIG. 5). The lid 42 has an opening 42A above the two adjustment members 54. Part of the other surface 542 (top surface) of the adjustment member 54 is exposed through the opening 42A. The adjustment member 54 of the gap adjustment device 501 is provided with a restriction portion 54R (see FIGS. 5 and 13). The restriction portion 54R is provided on the other surface 542 of the adjustment member 54 and protrudes upward from the opening 42A of the lid 42. The restriction portion 54R has a recessed shape like a funnel or a cylinder. The contact portion 11C of the head unit 11 is accommodated in the restriction portion 54R, thereby restricting movement of the contact portion 11C in a direction intersecting the first axis 51A.

[0034] [roller] The adjustment member 54 (see FIG. 13) of the gap adjustment device 501 is formed into a polygonal shape when viewed from above, with four sides aligned in the front-to-back and left-to-right directions, and the rear left and right corners of the rectangle being beveled. Rollers 561, 562, and 563, each with its axis extending horizontally, are in contact with the front, right, and left rear side surfaces of the adjustment member 54. Rollers 561, 562, and 563 restrict lateral movement of the adjustment member 54 and guide its movement in the up and down directions.

[0035] [Drive unit] The drive unit 70 (see FIGS. 4 and 13) drives the gap adjustment device 50. The drive force generated by the motor 71 is transmitted from a drive gear 71G provided on the drive shaft of the motor 71 to the first rotating member 51 of the gap adjustment device 502 via an idler gear 72, an idler gear 73, an idler gear 74, a worm 76, a worm wheel 77, and a drive gear 78 in this order. The drive force is also transmitted from the drive gear 78 to the first rotating member 51 of the gap adjustment device 501 via an idler gear 80 and an idler gear 81 in this order. The drive force is also transmitted from the idler gear 74 to the adjustment device 60 via a transmission shaft 75. The motor 71 is, for example, a stepping motor.

[0036] [Control Unit] The control unit 2 (see FIG. 2) stores conversion information that associates the thickness of the sheet with the rotation angle of the first rotating member 51. The control unit 2 calculates the rotation angle according to the thickness of the sheet supplied to the conveying path 10 from the conversion information, and drives the first rotating member 51 using the drive unit 70. As the first rotating member 51 rotates, the height of the step 51H that contacts the sphere 52B changes, and the adjustment member 54 moves in the direction of the first axis 51A together with the sphere 52B and the holder 53. As the adjustment member 54 moves, the head unit 11 moves in the direction of the first axis 51A. In this way, the gap between the head unit 11 and the conveying path 10 is adjusted according to the thickness of the sheet.

[0037] According to the gap adjustment device 50 of this embodiment, the position of the adjustment member 54 (gap adjustment in this embodiment) can be adjusted by rotating the first rotating member 51, which is more space-saving than a configuration in which a member with linear steps is slid. Furthermore, the height of the head unit 11 can be adjusted in both the up and down directions by rotating the first rotating member 51 in one direction, so no impact due to backlash occurs. Therefore, according to this embodiment, position adjustment can be performed without compromising space-saving features and durability. Furthermore, since the load applied to the first rotating member 51 and the adjustment member 54 is distributed to multiple locations, stress concentration can be suppressed. Furthermore, since the load is distributed around the first shaft 51A, distortion of the first rotating member 51 due to uneven load and adjustment errors can be suppressed.

[0038] [Detection System] Next, a detection system 200 according to this embodiment (see FIG. 13) will be described. The detection system 200 includes a gap adjustment device 50 (an example of a detection target device) and a detection device 90.

[0039] [Detection device] The detection device 90 is, for example, a potentiometer. The detection device 90 includes a second shaft 91A, a second rotating member 91, and a substrate 92. The second shaft 91A is supported on the substrate 92 with its axial direction aligned vertically. The second rotating member 91 is, for example, a spur gear with 15 teeth. A driving force is transmitted from the first rotating member 51 of the gap adjustment device 501 to the second rotating member 91 via the idler gear 82. A circuit including a variable resistor is provided on the substrate 92. The detection device 90 outputs a voltage corresponding to the rotation angle of the second rotating member 91.

[0040] FIG. 14 is a diagram illustrating the operation of the detection system 200 during one rotation of the first rotating member 51. FIG. 14(A) illustrates the relationship between the rotation angle θg [°] of the first rotating member 51 and the height [mm] of the step 51H with which the sphere 52B comes into contact. The horizontal axis of FIG. 14(A) represents the rotation angle when the first rotating member 51 is driven clockwise as viewed from above. The gap adjustment device 50 repeats an operation according to the rotation angle θg [°] of the first rotating member 51 every 1 / N rotation (N=3) of the first rotating member 51. This operation is an operation in which the height of the step 51H with which the sphere 52B comes into contact increases step by step from the lowest step 51H of the staircase portion 51S to the highest step 51H.

[0041] FIG. 14(B) shows the relationship between the rotation angle θs [°] of the second rotating member 91 and the output value Vo [%] of the detector 90. Because an idler gear 82 is interposed between the first rotating member 51 and the second rotating member 91, the second rotating member 91 rotates in the same direction as the first rotating member 51. In other words, the horizontal axis of FIG. 14(B) represents the rotation angle when the second rotating member 91 is driven clockwise as viewed from above. The vertical axis of FIG. 14(B) represents the ratio, expressed as a percentage, of the output value Vo [%] of the detector 90 to its maximum value. For every Nth rotation of the first rotating member 51, the second rotating member 91 rotates once. With each rotation of the second rotating member 91, the output value Vo [%] of the detector 90 monotonically increases from a minimum value to a maximum value according to the rotation angle θs [°] of the second rotating member 91. The output value Vo [%] of the detection device 90 may be configured to decrease monotonically.

[0042] As shown in FIG. 14 , the height of the step 51H with which the sphere 52B makes contact during one-Nth rotation of the first rotating member 51 is associated with the output value Vo [%] of the detection device 90 during one rotation of the second rotating member 91. With this configuration, the height of the step 51H with which the sphere 52B makes contact can be determined from the output value Vo [%] of the detection device 90. The control unit 2 determines whether the height of the step 51H with which the sphere 52B makes contact corresponds to the thickness of the sheet, and if the height of the step 51H corresponds to the thickness of the sheet, executes the image formation job. If the height of the step 51H is lower than the height corresponding to the thickness of the sheet, the control unit 2 drives the first rotating member 51 by one step in the clockwise direction and re-determines the height of the step 51H. On the other hand, if the height of the step 51H is higher than the height corresponding to the thickness of the sheet, the control unit 2 drives the first rotating member 51 by one step in the counterclockwise direction and re-determines the height of the step 51H.

[0043] In this embodiment, the amount of movement of the first rotating member 51 per 1 / N rotation is associated with the output value Vo [%] per rotation of the detection device 90, maximizing the resolution of the detection device 90. Therefore, the amount of movement of the device to be detected can be detected with high accuracy.

[0044] Figure 15 is a diagram showing the operation of the detection system 200 while the first rotating member 51 makes one-Nth rotation (N=3). That is, Figure 15(A) is a diagram in which the section θg=0 to 120[°] of Figure 14(A) is enlarged in the horizontal direction, and Figure 15(B) is a diagram in which the section θs=0 to 360[°] of Figure 14(B) is enlarged in the horizontal direction. Note that in Figure 15(B), the horizontal axis is replaced by -180 to 180[°].

[0045] 15(B), the output value Vo [%] of the detection device 90 (potentiometer) has a smaller gradient near the minimum and maximum values ​​compared to other sections, resulting in lower resolution. Also, as shown in FIG. 14(B), the output value Vo [%] discontinuously fluctuates from the maximum value to the minimum value at the timing of each rotation of the second rotating member 91, which may result in erroneous recognition of the height of the step 51H.

[0046] In contrast to this, in this embodiment, the range excluding the interval where the output value Vo [%] of the detection device 90 fluctuates discontinuously, in other words, the predetermined range where detection accuracy is guaranteed (see FIG. 15(B)), of the entire range from the minimum value to the maximum value of the output value Vo [%] of the detection device 90, is allocated to an area of ​​1 / Nth of a rotation of the first rotating member 51, thereby preventing erroneous recognition of the movement amount of the first rotating member 51. Therefore, according to this embodiment, the movement amount of the detection target device can be detected with high accuracy.

[0047] [Backlash compensation] Next, backlash correction according to this embodiment will be described. As described above, the height of the step 51H with which the sphere 52B comes into contact is determined from the output value Vo [%] of the detection device 90. The control unit 2 determines whether the height of the step 51H with which the sphere 52B comes into contact corresponds to the thickness of the sheet, and if the height of the step 51H corresponds to the thickness of the sheet, executes the image formation job. If the height of the step 51H is lower than the height corresponding to the thickness of the sheet, the control unit 2 drives the first rotating member 51 by one step in the clockwise direction and re-determines the height of the step 51H. On the other hand, if the height of the step 51H is higher than the height corresponding to the thickness of the sheet, the control unit 2 drives the first rotating member 51 by one step in the counterclockwise direction and re-determines the height of the step 51H.

[0048] However, when the rotation direction of the first rotating member 51 is changed, backlash in the gear train (idler gear 72, idler gear 73, idler gear 74, worm 76, worm wheel 77, drive gear 78, idler gear 80, idler gear 81) located between the drive gear 71G of the motor 71 and the first rotating member 51 causes a phase shift in the output value Vo [%] of the detection device 90.

[0049] FIG. 16 is a diagram showing the phase shift due to backlash when the rotation direction of the first rotating member 51 is changed. Here, TD1, TD2, TD3, TD4, and TD5 (see FIG. 12) are symbols that identify the height of the step 51H. The example in FIG. 16 shows how the phase shift is measured by rotating the first rotating member 51 from TD1 to TD2, TD3, and then TD4, and then rotating it in the reverse direction, TD3, and back to TD2. In this case, backlash BL occurs in the gear train during the process of returning to TD3 from TD3 to TD4. Therefore, a delay occurs in the change in the output value Vo [%] from the time the motor 71 is rotated in the reverse direction until the backlash BL is resolved. When the motor returns to TD2, a phase shift ΔV [%] occurs in the output value Vo [%] of the detection device 90.

[0050] Therefore, the control unit 2 calculates the number of motor steps corresponding to the phase shift ΔV [%] (hereinafter referred to as the number of backlash correction steps). In this example, the number of motor steps, 961 [steps], corresponds to 20 [%] of the output value Vo [%], so the number of backlash correction steps is calculated using equation (1). Backlash compensation step number = 961 × ΔV / 20 (1)

[0051] By adding the reverse rotation of the motor 71 by the number of backlash correction steps calculated by the formula (1), the output value Vo [%] of the detection device 90 is corrected.

[0052] In the above example, the initial state is TD1 and the process turns back at TD4, but to improve the accuracy of the correction, it is desirable to make the process of measuring the phase shift longer. Specifically, it is desirable to set the initial state to TD1, and it is more desirable to set the turning point of the process to TD4 rather than TD3, and it is even more desirable to set it to TD5 rather than TD4.

[0053] The detection system 200 according to the present embodiment described above includes a detection target device (gap adjustment device 50) including a first rotating member 51 that rotates about a first axis 51A, a detection device 90 including a second rotating member 91 that rotates about a second axis 91A by a driving force transmitted from the first rotating member 51 via a gear train (idler gear 72, idler gear 73, idler gear 74, worm 76, worm wheel 77, drive gear 78, idler gear 80, idler gear 81) and whose output value Vo [%] monotonically increases or decreases according to the rotation angle θs [°] of the second rotating member 91, and a control unit 2 that calculates a drive amount of the first rotating member 51 to correct the output value Vo [%] of the detection device 90 from a phase shift ΔV [%] of the output value Vo [%] of the detection device 90 when the rotation direction of the first rotating member 51 is changed. This configuration can suppress a decrease in detection accuracy due to backlash in the gear train.

[0054] Furthermore, in the detection system 200 according to this embodiment, the control unit 2 calculates the drive amount of the first rotating member 51 for correcting the output value Vo [%] of the detection device 90 from the phase shift ΔV [%] of the output value Vo [%] of the detection device 90 when the rotation direction of the first rotating member 51 is changed and the proportional relationship between the drive amount of the first rotating member 51 and the output value Vo [%] of the detection device 90. With this configuration, it is possible to suppress a decrease in detection accuracy due to backlash in the gear train.

[0055] Furthermore, in the detection system 200 according to this embodiment, the first rotating member 51 includes an intersecting surface 51C that intersects with the first axis 51A, and the detection target device includes a staircase portion 51S provided on the intersecting surface 51C and having a height that changes stepwise in the circumferential direction, an adjustment member 54 that faces the intersecting surface 51C and is movable in the direction of the first axis 51A, and a sphere 52B that is sandwiched between the adjustment member 54 and the intersecting surface 51C and whose movement in the circumferential direction is restricted, and the staircase portions 51S of the same pattern are provided at N locations (N is an integer of 2 or more) around the circumferential direction of the intersecting surface 51C, one sphere 52B is disposed on each of the N staircase portions 51S, and the spheres 52B contact steps 51H of the same height at the N staircase portions 51S. With this configuration, the height of the step 51H with which the sphere 52B is in contact can be detected with high accuracy.

[0056] Furthermore, according to the detection system 200 of this embodiment, the detection target device repeats an operation according to the rotation angle θg [°] of the first rotating member 51 every time the first rotating member 51 makes an Nth rotation, and the output value Vo [%] of the detection device 90 repeats a monotonous increase or decrease according to the rotation angle θs [°] of the second rotating member 91 every time the second rotating member 91 makes one rotation. According to this configuration, the amount of movement of the detection target device can be detected with high accuracy.

[0057] Furthermore, in the detection system 200 according to this embodiment, the detection device 90 is a potentiometer. With this configuration, the detection system 200 can be configured at low cost.

[0058] Furthermore, in the detection system 200 according to this embodiment, the first rotating member 51 and the second rotating member 91 are gears. With this configuration, it is possible to eliminate errors in the amount of movement due to slippage between the first rotating member 51 and the second rotating member 91.

[0059] The inkjet recording apparatus 1 according to this embodiment includes a head unit 11 that includes one or more inkjet heads 12 and contacts an adjustment member 54, and a detection system 200, and the control unit 2 controls the detection target device in accordance with the amount of movement of the detection target device detected by the detection system 200. This configuration allows the gap adjustment of the head unit 11 to be performed with high precision.

[0060] The above embodiment may be modified as follows.

[0061] In the above embodiment, an example was shown in which the first rotating member 51 was a spur gear, but the first rotating member 51 itself does not have to be a gear as long as it is configured to be driven to rotate around the first axis 51A. For example, a gear may be joined to the underside of the disk-shaped first rotating member 51 (not shown). The same applies to the second rotating member 91.

[0062] Furthermore, means other than gears may be used to transmit the driving force from the first rotating member 51 to the second rotating member 91. For example, the first rotating member 51 and the second rotating member 91 may be configured as magnetic gears.

[0063] In addition, in the above embodiment, an example is shown in which the first rotating member 51 has 45 teeth and the second rotating member 91 has 15 teeth, but these tooth numbers are only examples, and the tooth numbers may be different from these as long as the tooth number ratio between the first rotating member 51 and the second rotating member 91 is N:1 (N is an integer greater than or equal to 2).

[0064] Instead of the spheres 52B in the above embodiment, protrusions 52P (not shown) may be provided that protrude from one surface 541 of the adjustment member 54 and contact the intersecting surface 51C. In this case, the retainer 53 is not necessary. One protrusion 52P is arranged on each of the plurality of staircase portions 51S, and the protrusions 52P contact steps 51H of the same height in the plurality of staircase portions 51S. Even with this configuration, the height of the steps 51H that contact the protrusions 52P changes as the first rotating member 51 rotates, and the adjustment member 54 moves in the direction of the axis 51A.

[0065] In the above embodiment, an example in which the detection device 90 is a potentiometer has been shown, but the detection device 90 may be, for example, an absolute rotary encoder.

[0066] In the above embodiment, an example has been shown in which the detection system 200 is applied to gap adjustment of the head unit 11, but the detection system 200 can be applied to various other uses. For example, the detection system 200 may be used to position various movable parts, such as a shading plate of an image reading device, a separation claw that separates a sheet from a fixing roller of an electrophotographic device, etc.

[0067] In the above embodiment, an example has been shown in which the gear ratio between the first rotating member 51 and the second rotating member 91 is N:1, but the above backlash compensation can be applied even when the gear ratio between the first rotating member 51 and the second rotating member 91 is not N:1. Also, in the above embodiment, an example has been shown in which the detection device 90 is a potentiometer or an absolute type rotary encoder, but the above backlash compensation can be applied even when the detection device 90 is an incremental type rotary encoder. [Explanation of symbols]

[0068] 1. Inkjet recording device 2. Control section 11 Head Unit 12 Inkjet head 50 Gap adjustment device (detection target device) 51 first rotating member 51A 1st axis 51C Intersection 51H stage 51S Stairs 52B Sphere 54 Adjustment member 90 Detection Device 91 Second rotating member 91A 2nd axis 200 Detection System

Claims

1. a detection target device including a first rotating member that rotates around a first axis; a detection device including a second rotating member that rotates about a second axis by a driving force transmitted from the first rotating member via a gear train, and an output value of which monotonically increases or decreases according to a rotation angle of the second rotating member; a control unit that calculates a drive amount of the first rotating member to correct the output value of the detection device from a phase shift of the output value of the detection device when the rotation direction of the first rotating member is changed.

2. The detection system described in claim 1, characterized in that the control unit calculates the driving amount of the first rotating member to correct the output value of the detection device based on the phase shift of the output value of the detection device when the rotation direction of the first rotating member is changed and the proportional relationship between the driving amount of the first rotating member and the output value of the detection device.

3. the first rotating member has an intersecting surface that intersects with the first axis, The detection target device is a step portion provided on the intersecting surface and having a height that changes stepwise in a circumferential direction; an adjustment member facing the intersecting surface and movable in the first axial direction; a sphere sandwiched between the adjustment member and the intersecting surface and restricted in its movement in the circumferential direction, or a protrusion protruding from the adjustment member and contacting the intersecting surface, The stepped portions having the same pattern are provided at N locations (N is an integer of 2 or more) in the circumferential direction of the intersecting surface, One sphere or one protrusion is disposed on each of the N step portions, 3. The detection system according to claim 1, wherein the sphere or the protrusion contacts steps of the same height in the N number of the staircase portions.

4. the detection target device repeats an operation according to the rotation angle of the first rotating member every time the first rotating member makes 1 / N rotation, 2. The detection system according to claim 1, wherein the output value of the detection device repeats a monotonous increase or decrease depending on the rotation angle of the second rotating member each time the second rotating member rotates once.

5. 2. The sensing system of claim 1, wherein the sensing device is a potentiometer.

6. 2. The detection system of claim 1, wherein the first rotating member and the second rotating member are gears.

7. a head unit including one or more inkjet heads and in contact with the adjustment member; The detection system according to claim 3, The inkjet recording apparatus is characterized in that the control unit controls the detection target device in accordance with the amount of movement of the detection target device detected by the detection system.

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