Detection system and inkjet recording device

Abstract

To highly accurately detect an operation amount of a detection object device.SOLUTION: A detection system 200 includes a first rotation member 51 rotating around a first axis, a detection object device (for example, gap adjustment device 50) for repeating operation according to a rotation angle of the first rotation member 51 every time the first rotation member 51 rotates a 1 / N turn (N is an integer of 2 or larger), a second rotation member 91 rotating around a second axis 91A by driving force transmitted from the first rotation member 51, and a detection device 90 in which an output value repeats monotonous increase or monotonous decrease according to a rotation angle of the second rotation member 91, every time the second rotation member 91 rotates a turn, in which the second rotation member 91 rotates a turn every time the first rotation member 51 rotates a 1 / N turn.SELECTED DRAWING: Figure 13

Description

[Technical field]

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

[0002] In order to obtain good image quality in an inkjet recording device, it is necessary to optimize the gap between the conveyed sheet and the inkjet head. Therefore, conventionally, a technique for adjusting the gap according to the thickness of the sheet has been considered. For example, in the configuration disclosed in Patent Document 1, the height of the inkjet head changes depending on the presence or absence of a sheet and its thickness. The sensor is a photointerrupter, and light is blocked when a sheet is not present below the carriage. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2015-142994 A Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, a possible means for adjusting the gap is to support the inkjet head via a stepped member that corresponds to various sheet thicknesses, and change the height of the inkjet head by sliding the stepped member. In this case, the gap is guaranteed to be appropriate by checking the amount of movement of the stepped member, but in order to accommodate sheets of various thicknesses, it is necessary to improve the accuracy of detecting the amount of movement.

[0005] The present invention has been made in consideration of the above circumstances, and has an object to detect the amount of operation of a detection target device with high accuracy. [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 which includes a first rotating member which rotates around a first axis and which repeats an operation according to the rotation angle of the first rotating member every time the first rotating member makes 1 / N rotation (N is an integer greater than or equal to 2), and a detection device which includes a second rotating member which rotates around a second axis by a driving force transmitted from the first rotating member and whose output value monotonically increases or decreases according to the rotation angle of the second rotating member every time the second rotating member makes one rotation, and the second rotating member rotates once every 1 / N rotation of the first rotating member.

[0007] The first rotating member has an intersecting surface that intersects with the first axis, and the detection target device has a step portion provided on the intersecting surface and whose height changes in a stepped manner 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, and the step portions of the same pattern are provided at N locations in the circumferential direction of the intersecting surface, and one of the spheres or one of the protrusions is arranged in each of the N step portions, and the sphere or the protrusion contacts steps of the same height at the N step portions.

[0008] The sensing device may be a potentiometer.

[0009] The first rotating member and the second rotating member may be gears.

[0010] In addition, the inkjet recording device of the present invention includes a head unit having one or more inkjet heads and contacting the adjustment member, the detection system, and a control unit that controls the detection target device in accordance with the amount of operation of the detection target device detected by the detection system. Effect of the Invention

[0011] According to the present invention, the amount of operation of a detection target device can be detected with high accuracy. [Brief description of the drawings]

[0012] [Figure 1] 1 is a perspective view showing an external appearance of an image forming system according to an embodiment of the present invention; [Diagram 2] 1 is a front view showing a schematic internal configuration of an inkjet recording apparatus according to an embodiment of the present invention; [Diagram 3] FIG. 2 is a perspective view showing a head unit according to an embodiment of the present invention. [Figure 4] FIG. 2 is a perspective view showing a head unit according to an embodiment of the present invention. [Diagram 5] FIG. 2 is a perspective view showing an adjustment device according to an embodiment of the present invention. [Figure 6] 1 is a perspective view showing a gap adjustment device according to an embodiment of the present invention; [Figure 7] FIG. 2 is a perspective view showing a rotating member, a sphere, and a cage according to an embodiment of the present invention. [Figure 8] FIG. 2 is a perspective view showing a rotating member and a sphere according to an embodiment of the present invention. [Figure 9] FIG. 2 is a perspective view showing a rotating member according to an embodiment of the present invention. [Figure 10] FIG. 7 is a cross-sectional view showing a cross section II of FIG. [Figure 11] FIG. 2 is a plan view showing a rotating member according to an embodiment of the present invention. [Figure 12] 12 is a cross-sectional view showing the II-II cross section of FIG. 11. [Figure 13] FIG. 1 is a perspective view of a detection system according to an embodiment of the present invention. [Figure 14] 6A to 6C are diagrams illustrating the operation of the detection system during one rotation of the first rotating member. [Figure 15] FIG. 13 is a diagram showing the operation of the detection system during 1 / N rotation (N=3) of the first rotating member. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] 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.

[0014] Fig. 1 is a perspective view showing the exterior of an image forming system 100. Fig. 2 is a front view showing a schematic 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 respectively indicate up, down, left, right, front, and rear.

[0015] 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.

[0016] 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 port 8 that introduces a sheet from a paper feed device 110 is provided on the right side of the main housing 3. A discharge port 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, which runs from the paper feed port 8 through a gap between the transport unit 7 and the imaging unit 6 to the discharge port 9. A registration roller 18 is provided upstream of the transport unit 7 in the transport direction Y.

[0017] The transport unit 7 includes an endless transport belt 21 and a suction section 24. The transport belt 21 has many ventilation holes (not shown) and is wound around a drive roller 25 and a driven roller 22. The upper surface of the suction section 24 has many ventilation holes (not shown) and is in contact with the inner surface of the transport belt 21. The suction section 24 sucks air through the ventilation holes of the transport belt 21 and the ventilation holes of the suction section 24, thereby adsorbing the sheet to the transport belt 21. The drive roller 25 is driven in the counterclockwise direction by a drive section (not shown) including a motor and a reduction gear, so that the transport belt 21 rotates in the counterclockwise direction, and the sheet adsorbed to the transport belt 21 is transported.

[0018] 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). Ink containers 20 filled with black, cyan, magenta, and yellow ink are connected to the four head units 11, respectively. A maintenance device 30 for performing maintenance on the inkjet heads 12 is provided to the right of each head unit 11.

[0019] 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. The control unit 2 may be realized by an integrated circuit that does not use software.

[0020] A display operation unit 19 is provided on the upper part of the main body housing 3 (see Figs. 1 and 2). The display operation unit 19 includes a display panel, a touch panel laminated 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.

[0021] The basic image forming operation of the inkjet recording device 1 is as follows. When an image formation job is input to the inkjet recording device 1 from the display operation unit 19 or an external computer, the paper feeder 110 sends out a sheet to the transport path 10 through the paper feed port 8, and the registration rollers 18, whose rotation has been stopped, correct any skew of the sheet. When the registration rollers 18 send out the sheet to the transport unit 7 at a predetermined timing, the transport unit 7 attracts the sheet to the transport belt 21 and transports it in the Y direction. Ink is ejected from the nozzles onto the sheet, and an image is formed. The sheet on which the image has been formed is discharged to the drying device 120 through the discharge port 9.

[0022] [Adjustment device] The rear end and front end of the head unit 11 are supported by adjustment devices 40 and 60, respectively. The adjustment devices 40 and 60 have the function of adjusting the position of the head unit 11 in the up-down direction.

[0023] 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 rotating member 51, the sphere 52B, and the holder 53. FIG. 8 is a perspective view showing the rotating member 51 and the sphere 52B. FIG. 9 is a perspective view showing the rotating member 51. FIG. 10 is a cross-sectional view showing the II section of FIG. 6. FIG. 11 is a plan view showing the rotating member 51. FIG. 12 is a cross-sectional view showing the II-II section of FIG. 11. FIG. 13 is a perspective view showing the detection system 200.

[0024] The head unit 11 (see FIGS. 3 and 4) includes three inkjet heads 12 arranged in a staggered manner, and a frame 11F supporting the three inkjet heads 12. Contact portions 11C are provided at two locations in the left-right direction on both the front and rear ends of the bottom of the frame 11F. The contact portions 11C are, for example, pins protruding 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, 60 support the head unit 11 via the contact portions 11C. The adjustment device 40 will be described below as an example.

[0025] The adjustment device 40 (see FIG. 5) has a rectangular parallelepiped housing 41 with the longitudinal direction being 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 basic configuration of the right-side gap adjustment device 501 and the left-side gap adjustment device 502 is the same.

[0026] [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 sphere 52B, and a retainer 53.

[0027] [First shaft, first rotating member] The first shaft 51A is supported by the housing 41 with the vertical direction as the axial 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 intersecting with the first shaft 51A. The intersecting surface 51C is provided with a step portion 51S whose height changes stepwise in the circumferential direction. The step portions 51S of the same pattern are provided at a plurality of locations in the circumferential direction of the intersecting surface 51C. In this embodiment, the step portions 51S of the same pattern are provided at three locations in the circumferential direction of the intersecting surface 51C.

[0028] [Stairs section] The staircase portion 51S includes five steps 51H arranged in the circumferential direction and four inclined surfaces 51G connecting two adjacent steps 51H. The five steps 51H are provided so that their height increases stepwise in the 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.

[0029] [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 rotating member 51. One surface 541 (e.g., the lower surface) of the adjustment member 54 faces the intersecting surface 51C of the first rotating member 51, and the other surface 542 (e.g., the upper surface) of the adjustment member 54 faces the bottom of the frame 11F. 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.

[0030] [sphere] Between one surface 541 of the adjustment member 54 and the intersecting surface 51C, a sphere 52B (see Figs. 7, 8, and 10) is provided. One sphere 52B is arranged in each of the plurality of step portions 51S. The three spheres are arranged at intervals of 120°. That is, the sphere 52B contacts the steps 51H of the same height in the plurality of step portions 51S. The sphere 52B is held by a holder 53. The holder 53 restricts the relative movement of the sphere 52B with respect to the holder 53. Parts of the sphere 52B protrude from the upper and lower surfaces of the holder 53. The holder 53 is supported by the housing 41 and the first shaft 51A, and is slidable in the direction of the first shaft 51A, but is restricted from rotating around the first shaft 51A. With this configuration, the movement of the sphere 52B in the circumferential direction is restricted. As the first rotating member 51 rotates, the height of the step 51H that contacts the sphere 52B changes, so that the adjustment member 54 moves together with the sphere 52B and the retainer 53 in the direction of the first axis 51A.

[0031] [Regulation Department] The upper part of the gap adjustment device 50 is covered with a lid 42. The lid 42 has an opening 42A (see FIG. 5) above the two adjustment members 54. At the opening 42A, a part of the other surface 542 (upper surface) of the adjustment member 54 is exposed. The adjustment member 54 of the gap adjustment device 501 is provided with a regulating portion 54R. The regulating 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 regulating 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 regulating portion 54R, thereby regulating the movement of the contact portion 11C in a direction intersecting the first axis 51A.

[0032] [roller] The adjustment member 54 of the gap adjustment device 501 is formed into a hexagon with four sides aligned along the front-rear and left-right directions when viewed from above, with the left and right rear corners of the rectangle being cut off at an angle. Rollers 561, 562, 563, each with an axial direction extending horizontally, are in contact with the front, right, and left rear side surfaces of the adjustment member 54. The rollers 561, 562, 563 restrict the lateral movement of the adjustment member 54 and guide its movement in the up-down direction.

[0033] [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.

[0034] [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 obtains a 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 by the drive unit 70. As the first rotating member 51 rotates, the height of the step 51H that contacts the sphere 52B changes, so that the adjustment member 54 moves in the first axis 51A direction together with the sphere 52B and the holder 53. As the adjustment member 54 moves, the head unit 11 moves in the first axis 51A direction. In this way, the gap of the head unit 11 with respect to the conveying path 10 is adjusted according to the thickness of the sheet.

[0035] 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, and therefore, compared to a configuration in which a member with linear steps is slid, this is more space-saving. Also, 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, the position adjustment can be performed without reducing space-saving properties and durability. Also, 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. Also, 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.

[0036] [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.

[0037] [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 by the substrate 92 with the vertical direction as the axial direction. 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. The substrate 92 is provided with a circuit including a variable resistor. The detection device 90 outputs a voltage according to the rotation angle of the second rotating member 91.

[0038] FIG. 14 is a diagram showing the operation of the detection system 200 while the first rotating member 51 rotates once. Of these, FIG. 14(A) is a diagram showing 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) shows the rotation angle when the first rotating member 51 is driven in the clockwise direction as viewed from above. The gap adjustment device 50 repeats an operation according to the rotation angle of the first rotating member 51 every time the first rotating member 51 makes an Nth rotation (N=3). 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.

[0039] FIG. 14B is a diagram showing the relationship between the rotation angle θs [°] of the second rotating member 91 and the output value Vo [%] of the detection device 90. Since the 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. 14B indicates the rotation angle when the second rotating member 91 is driven in the clockwise direction as viewed from above. The vertical axis of FIG. 14B indicates the ratio to the maximum output value of the detection device 90 as a percentage. Every time the first rotating member 51 rotates 1 / N, the second rotating member 91 rotates once. Every time the second rotating member 91 rotates once, the output value of the detection device 90 repeats a monotonous increase from a minimum value to a maximum value according to the rotation angle of the second rotating member 91. The detection device 90 may be configured to monotonously decrease its output value.

[0040] As shown in FIG. 14, the height of the step 51H with which the sphere 52B contacts during one Nth rotation of the first rotating member 51 is associated with the output value of the detector 90 during one rotation of the second rotating member 91. With this configuration, the height of the step 51H with which the sphere 52B contacts is obtained from the output value of the detector 90. The control unit 2 determines whether the height of the step 51H with which the sphere 52B contacts corresponds to the thickness of the sheet, and executes an image forming job if the height of the step 51H corresponds to the thickness of the sheet. 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 to re-determine 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 to re-determine the height of the step 51H.

[0041] In this embodiment, the amount of movement of the first rotating member 51 for each 1 / Nth rotation is associated with the output value of the detection device 90 for each rotation, maximizing the resolution of the detection device 90. Therefore, the amount of movement of the detection target device can be detected with high accuracy.

[0042] Fig. 15 is a diagram showing the operation of the detection system 200 while the first rotating member 51 rotates 1 / N (N=3). That is, Fig. 15(A) is a diagram in which the section of θg=0 to 120[°] in Fig. 14(A) is enlarged in the horizontal direction, and Fig. 15(B) is a diagram in which the section of θs=0 to 360[°] in Fig. 14(B) is enlarged in the horizontal direction. In Fig. 15(B), the horizontal axis is replaced by -180 to 180[°].

[0043] As shown in Fig. 15(B), the output value of the detection device 90 (potentiometer) has a smaller gradient near the minimum and maximum values ​​compared to other sections, resulting in a lower resolution. Also, as shown in Fig. 14(B), the output value discontinuously changes 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.

[0044] In contrast, in this embodiment, the range of the entire range from the minimum value to the maximum value of the output value of the detection device 90 excluding the section where the output value fluctuates discontinuously, in other words, a predetermined range where detection accuracy is guaranteed (see FIG. 15(B)), is assigned to an area of ​​1 / Nth rotation of the first rotating member 51, so that it is possible to prevent 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.

[0045] The detection system 200 according to the present embodiment described above includes a detection target device (for example, gap adjustment device 50) that includes a first rotating member 51 that rotates around a first axis 51A and repeats an operation according to the rotation angle of the first rotating member 51 every time the first rotating member 51 makes 1 / N rotation (N is an integer equal to or greater than 2), and a detection device 90 that includes a second rotating member 91 that rotates around a second axis 91A by a driving force transmitted from the first rotating member 51 and repeats an output value monotonically increasing or decreasing according to the rotation angle of the second rotating member 91 every time the second rotating member 91 makes one rotation, and the second rotating member 91 makes one rotation every time the first rotating member 51 makes 1 / N rotation. With this configuration, the amount of movement of the detection target device can be detected with high accuracy.

[0046] According to the detection system 200 of this embodiment, the first rotating member 51 has an intersecting surface 51C intersecting with the first axis 51A, and the detection target device (gap adjustment device 50) has a step portion 51S provided on the intersecting surface 51C and changing in height in a step-like manner in the circumferential direction, an adjustment member 54 facing the intersecting surface 51C and movable in the first axis 51A direction, and a sphere 52B sandwiched between the adjustment member 54 and the intersecting surface 51C and restricted in its movement in the circumferential direction, and the step portions 51S of the same pattern are provided at N locations in the circumferential direction of the intersecting surface 51C, one sphere 52B is arranged on each of the N step portions 51S, and the sphere 52B contacts the steps 51H of the same height in the N step portions 51S. According to this configuration, the height of the step 51H with which the sphere 52B is in contact can be detected with high accuracy.

[0047] Moreover, 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.

[0048] 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, an error in the amount of movement caused by slippage between the first rotating member 51 and the second rotating member 91 can be eliminated.

[0049] Moreover, the inkjet recording apparatus 1 according to this embodiment includes a head unit 11 having one or more inkjet heads 12 and in contact with an adjustment member 54, a detection system 200, and a control unit 2 that controls the detection target device in accordance with the amount of operation of the detection target device detected by the detection system 200. With this configuration, the gap adjustment of the head unit 11 can be performed with high accuracy.

[0050] The above embodiment may be modified as follows.

[0051] In the above embodiment, an example in which the first rotating member 51 is a spur gear has been shown, 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 shaft 51A. For example, a gear may be joined to the lower surface of the disk-shaped first rotating member 51 (not shown). The same applies to the second rotating member 91.

[0052] 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 with magnetic gears.

[0053] 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 numbers of teeth are merely examples, and the numbers of teeth 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.

[0054] Instead of the spheres 52B in the above embodiment, protrusions 52P (not shown) may be provided that protrude from one surface 541 of the gap adjustment member 54 and contact the intersecting surface 51C. In this case, the retainer 53 is not necessary. One protrusion 52P is disposed on each of the multiple staircase portions 51S, and the protrusions 52P contact steps 51H of the same height in the multiple staircase portions 51S. With this configuration as well, the height of the step 51H that contacts the protrusions 52P changes as the rotating member 51 rotates, so that the gap adjustment member 54 moves in the direction of the axis 51A.

[0055] 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 type rotary encoder.

[0056] In the above embodiment, an example has been shown in which the detection system 200 is applied to the 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 for positioning 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, and the like. [Explanation of symbols]

[0057] 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 52P protrusion 54 Adjustment parts 90 Detection Device 91 Second rotating member 91A 2nd axis

Claims

1. a detection target device including a first rotating member that rotates around a first axis, the detection target device repeating an operation according to a rotation angle of the first rotating member every time the first rotating member makes 1 / N rotation (N is an integer equal to or greater than 2); a detection device including a second rotating member that rotates around a second axis by a driving force transmitted from the first rotating member, and an output value that repeats monotonically increasing or monotonically decreasing in accordance with a rotation angle of the second rotating member every time the second rotating member rotates once, A detection system, comprising: said second rotating member rotating once for every Nth rotation of said first rotating member.

2. 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 that is sandwiched between the adjustment member and the intersecting surface and whose movement in the circumferential direction is restricted, or a protrusion that protrudes from the adjustment member and contacts the intersecting surface, The stepped portion having the same pattern is provided at N locations in the circumferential direction of the intersecting surface, One of the spheres or one of the protrusions is disposed on each of the N step portions; 2. The detection system according to claim 1, wherein the sphere or the protrusion comes into contact with steps of the same height in N number of the staircase portions.

3. 3. The sensing system according to claim 1, wherein the sensing device is a potentiometer.

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

5. a head unit including one or more inkjet heads and in contact with the adjustment member; A detection system according to claim 2; a control unit that controls the detection target device in response to an amount of operation of the detection target device detected by the detection system.

Images