Punching device and sheet post-processing device

Abstract

To provide a punching device which achieves reduction in size.SOLUTION: A punching device 2 includes a punching blade 31, a holder 33, an energization member 34, an eccentric cam 35, and a punching guide 32. The punching blade 31 forms a hole on a sheet. The holder 33 holds the punching blade 31. The energization member 34 energizes the holder 33 in a retreat direction at which the punching blade 31 is separated from the sheet. The eccentric cam 35 is brought into contact with the holder 33, is rotated against energization force of the energization member 34, and moves the holder 33 in a punching direction at which the punching blade 31 approaches the sheet. The punching guide 32 extends in the moving direction to the sheet of the punching blade 31 and guides the movement of the punching blade 31. When the holder 33 is moved in the punching direction, the eccentric cam 35 passes through the side of the punching guide 32 so as to overlap the punching guide 32 when being viewed from a rotation axis direction of the eccentric cam 35.SELECTED DRAWING: Figure 7

Description

Technical Field

[0001] The present invention relates to a punching device for performing a punching process on a sheet and a sheet post-processing device.

Background Art

[0002] There is known a sheet post-processing device that performs predetermined post-processing on a sheet after an image is formed by an image forming device such as a copying machine or a printer. The sheet post-processing device may be equipped with a punching device that forms holes (punch holes) by performing a punching process on the sheet.

[0003] For example, a conventional punching device disclosed in Patent Document 1 includes a punch blade that forms punch holes in a sheet, an eccentric cam that contacts the punch blade and moves the punch blade toward the sheet by rotating, and a guide member that guides the movement of the punch blade. The punch blade moves toward the sheet while being guided by the guide member as the eccentric cam rotates, and forms punch holes in the sheet.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the prior art, the eccentric cam is always positioned in a region on the opposite side of the arrangement region of the guide member from the punching position of the sheet by the tip of the punch blade during rotation, and there is a problem that the length of the punching device along the moving direction of the punch blade becomes long. As a result, there was a concern about the enlargement of the punching device.

[0006] The present invention has been made in view of the above points, and an object thereof is to provide a punching device and a sheet post-processing device that are downsized.

Means for Solving the Problem

[0007] To solve the above problems, the punching device of the present invention includes a punching blade, a holder, a biasing member, an eccentric cam, and a punching guide. The punching blade forms a hole in the sheet. The holder holds the punching blade. The biasing member biases the holder in a retracting direction in which the punching blade moves away from the sheet. The eccentric cam contacts the holder and rotates against the biasing force of the biasing member to move the holder in a punching direction in which the punching blade approaches the sheet. The punching guide extends in a moving direction of the punching blade with respect to the sheet and guides the movement of the punching blade. When moving the holder in the punching direction, the eccentric cam passes through a side of the punching guide so as to overlap the punching guide when viewed from a direction of a rotation axis of the eccentric cam.

Advantages of the Invention

[0008] According to the configuration of the present invention, the eccentric cam passes through the side of the punching guide during rotation. That is, the eccentric cam does not always locate in a region on the opposite side of the arrangement region of the punching guide from the punching position of the sheet by the tip of the punching blade during rotation. Thereby, the length of the punching device along the moving direction of the punching blade can be shortened. Therefore, it becomes possible to miniaturize the punching device.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Embodiments for Carrying Out the Invention

[0010] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the following content.

[0011] Fig. 1 is a schematic cross-sectional front view of an image forming apparatus 200 including a sheet post-processing apparatus 1 according to an embodiment. As an example of the image forming apparatus 200 of the present embodiment, for example, a so-called multifunction machine corresponding to monochrome printing having functions such as printing, scanning (image reading), facsimile transmission, etc. may be used. Note that the image forming apparatus 200 may be, for example, a device such as a copying machine or a printer, and may also be a machine corresponding to color printing.

[0012] As shown in Fig. 1, the image forming apparatus 200 includes a document conveyance unit 202 and an image reading unit 203. The document conveyance unit 202 is placed on the upper surface of the main body 201 of the image forming apparatus 200. The image reading unit 203 is disposed inside the main body 201 below the document conveyance unit 202. An image of a document loaded on the document conveyance unit 202 or an image of a document placed on a contact glass (not shown) on the upper surface of the image reading unit 203 is read by the image reading unit 203.

[0013] The image forming apparatus 200 further includes a sheet feeding unit 204, a sheet conveyance unit 205, an exposure unit 206, an image forming unit 207, a transfer unit 208, a fixing unit 209, the sheet post-processing apparatus 1, a sheet discharging unit 210, and a control unit 211, which are provided in the main body 201 thereof.

[0014] The sheet feeding unit 204 is disposed at the bottom of the main body 201. The sheet feeding unit 204 stores a plurality of sheets S before the images are printed, and separates and feeds the sheets S one by one during printing. The sheet conveyance unit 205 extends vertically along the side wall of the main body 201. The sheet conveyance unit 205 conveys the sheet S sent out from the sheet feeding unit 204 to the transfer unit 208 and the fixing unit 209, and further conveys the sheet S after fixing to the sheet post-processing device 1. The exposure unit 206 irradiates the image forming unit 207 with laser light controlled based on image data.

[0015] The image forming unit 207 is disposed above the sheet feeding unit 204. The image forming unit 207 includes a photosensitive drum 2071 and a developing unit 2072. In the image forming unit 207, an electrostatic latent image of the original image is formed on the outer peripheral surface of the photosensitive drum 2071 by the laser light irradiated from the exposure unit 206. The developing unit 2072 supplies toner to the electrostatic latent image on the outer peripheral surface of the photosensitive drum 2071 for development to form a toner image. The transfer unit 208 transfers the toner image formed on the outer peripheral surface of the photosensitive drum 2071 to the sheet S.

[0016] The fixing unit 209 is disposed above the transfer unit 208. The fixing unit 209 fixes the toner image to the sheet S by heating and pressing the sheet S onto which the toner image has been transferred.

[0017] The sheet post-processing device 1 is detachably attached inside the body of the main body 201 of the image forming device 200. The sheet S on which the toner image has been fixed and the printing is completed in the fixing unit 209 is carried into the sheet post-processing device 1 through the sheet carry-in port 1e. The sheet post-processing device 1 includes a punching device 2, a processing tray 3, and a stapling device 4.

[0018] The punching device 2 is arranged on the downstream side in the sheet conveyance direction of the sheet conveyance inlet 1e. The punching device 2 performs a punching process on the conveyed sheet S to form holes (punch holes). The processing tray 3 is arranged on the downstream side in the sheet conveyance direction of the punching device 2. On the processing tray 3, a plurality of sheets S are stacked to form a sheet bundle, and the alignment of the sheet bundle is performed. The stapling device 4 is arranged on the upstream side in the sheet conveyance direction of the processing tray 3. The stapling device 4 performs a stapling process (binding process) on the sheet bundle stacked on the processing tray 3 to bind the sheet bundle.

[0019] The sheet discharge unit 210 is a side wall on the side opposite to the side wall of the main body 201 adjacent to the sheet conveyance unit 205, and is arranged on the downstream side in the sheet conveyance direction of the sheet post-processing device 1. The sheet S that has passed through the sheet post-processing device 1 is conveyed to the sheet discharge unit 210 and discharged onto the tray.

[0020] The control unit 211 includes a CPU, a storage unit, an image processing unit, and other electronic circuits and electronic components (all not shown). The CPU controls the operations of the respective components provided in the image forming apparatus 200 based on the control programs and data stored in the storage unit, and performs processes related to the functions of the image forming apparatus 200. Each of the sheet feeding unit 204, the sheet conveyance unit 205, the exposure unit 206, the image forming unit 207, the transfer unit 208, the fixing unit 209, and the sheet post-processing device 1 receives individual commands from the control unit 211 and performs printing on the sheet S in conjunction.

[0021] Regarding the control of the sheet post-processing device 1, the control functions of the control unit 211 may be provided in the sheet post-processing device 1.

[0022] Subsequently, the schematic configuration of the punching device 2 of the sheet post-processing device 1 will be described with reference to FIG. 2. FIG. 2 is a perspective view of the punching device 2 of the sheet post-processing device 1 in FIG. 1. In the following figures, arrow lines indicating the sheet conveyance direction Dc and the sheet width direction Dw orthogonal to the sheet conveyance direction Dc are appropriately drawn.

[0023] As shown in FIG. 2, the punching device 2 includes a punching motor 21, a rotation detection unit 22, a shaft 23, an upper guide member 24, a lower guide member 25, and a punching unit 30.

[0024] The punching motor 21 is disposed at one end of the punching device 2 in the sheet width direction Dw. The punching motor 21 is connected to the shaft 23 via a gear and rotates the shaft 23. For example, a DC brush motor can be used as the punching motor 21.

[0025] The rotation detection unit 22 is disposed adjacent to the connection portion between the punching motor 21 and the shaft 23. The rotation detection unit 22 detects the rotation of the shaft 23. The rotation detection unit 22 includes a first pulse plate 221, a second pulse plate 222, and a sensor unit 223.

[0026] The first pulse plate 221 and the second pulse plate 222 are fixed to the shaft 23 and are configured in a disk shape that rotates around the axis of the shaft 23 together with the shaft 23. The first pulse plate 221 has a plurality of slits that penetrate in the sheet width direction Dw and are arranged at equal angular intervals in the circumferential direction on the outer peripheral portion. The second pulse plate 222 has a single notch portion arranged at the radially outer edge portion and penetrating in the sheet width direction Dw.

[0027] The sensor unit 223 includes a first sensor and a second sensor (both not shown). The first sensor and the second sensor are transmissive optical sensors having a light emitting portion and a light receiving portion. The first sensor and the second sensor are arranged such that the outer peripheral portions of the first pulse plate 221 and the second pulse plate 222 fixed to the shaft 23 pass through their respective optical paths. The control unit 211 detects the rotation speed of the shaft 23 based on the output (pulse period) of the first sensor. The control unit 211 detects that the rotation angle of the shaft 23 has reached the reference angle (home position) based on the output of the second sensor.

[0028] The shaft 23 extends across both end portions of the punching device 2 in the sheet width direction Dw. The shaft 23 is connected to the punching motor 21 via a gear, obtains power from the punching motor 21, and rotates about an axis extending in the sheet width direction Dw. The shaft 23 reciprocates the punching blade 31, which will be described later, of the punching portion 30.

[0029] The upper guide member 24 and the lower guide member 25 are disposed below the shaft 23. The upper guide member 24 and the lower guide member 25 are formed of plate-like members extending in the sheet conveyance direction Dc and the sheet width direction Dw. The upper guide member 24 and the lower guide member 25 are disposed to face each other in the vertical direction with a gap of a predetermined interval therebetween. The gap between the upper guide member 24 and the lower guide member 25 is the sheet conveyance path Rs.

[0030] The punching portion 30 is disposed above the upper guide member 24. In the present embodiment, the punching device 2 includes four punching portions 30 juxtaposed at predetermined positions in the sheet width direction Dw along the shaft 23. The punching portion 30 obtains power from the shaft 23 penetrating in the sheet width direction Dw, and performs a punching process on the sheet S passing between the upper guide member 24 and the lower guide member 25 to form holes (punch holes).

[0031] Subsequently, a detailed configuration of the punching portion 30 of the punching device 2 will be described with reference to FIGS. 3 to 8 in addition to FIG. 2. FIGS. 3, 4, and 5 are a partially enlarged perspective view, a vertical cross-sectional front view, and a vertical cross-sectional side view of the punching device 2 in FIG. 2. FIG. 6 is a vertical cross-sectional front view of the punching guide 32 of the punching device 2 in FIG. 2. FIGS. 7 and 8 are a vertical cross-sectional front view and a vertical cross-sectional side view showing a punching state of the punching device 2 in FIG. 2. In FIG. 3, the drawing of the cam cover 36 is omitted.

[0032] As shown in FIGS. 3, 4, and 5, the punching portion 30 includes a punching blade 31, a punching guide 32, a holder 33, a biasing member 34, an eccentric cam 35, a cam cover 36, and a connecting pin 37.

[0033] The punching blade 31 is disposed above the upper guide member 24 and vertically below the shaft 23. The punching blade 31 is a cylindrical or tubular member extending in the normal direction (upward direction) of one surface of the sheet S conveyed through the sheet conveyance path Rs between the upper guide member 24 and the lower guide member 25. In the present embodiment, the punching blade 31 is a metal pipe, and a blade tip 31e is formed at the lower end portion. The punching blade 31 forms a hole in the sheet S conveyed through the sheet conveyance path Rs.

[0034] The upper guide member 24 and the lower guide member 25 have through holes 24h and 25h. The through holes 24h and 25h are disposed at positions facing the punching blade 31 in the vertical direction. As shown in FIGS. 7 and 8, the punching blade 31 that moves in the vertical direction when punching and retracting the sheet S conveyed through the sheet conveyance path Rs passes through the through holes 24h and 25h.

[0035] The punching guide 32 is fixed above the upper guide member 24. Further, the punching guide 32 is located below the shaft 23. The punching guide 32 is formed in a cylindrical shape extending in the moving direction of the punching blade 31 with respect to the sheet S, that is, in the vertical direction. The punching blade 31 moves vertically within the punching guide 32. The punching guide 32 guides the movement of the punching blade 31.

[0036] The holder 33 is disposed outside the radial direction of the punching blade 31 and the punching guide 32, which are cylindrical or tubular and are above the punching blade 31. The holder 33 is disposed at the central portion when viewed in the vertical direction, and has a hole portion 33h that penetrates in the vertical direction and through which the punching blade 31 and the punching guide 32 pass. Further, the holder 33 is located below the shaft 23.

[0037] The holder 33 is connected to the upper portion of the punching blade 31 via a connection pin 37. The holder 33 holds the punching blade 31. When the punching blade 31 moves in the vertical direction, the holder 33 moves in the vertical direction outside the radial direction of the punching guide 32.

[0038] The biasing member 34 is located radially outside the punching guide 32 and is disposed between the holder 33 and the upper guide member 24 in the vertical direction. The biasing member 34 is composed of a compression coil spring, and the punching blade 31 and the punching guide 32 are positioned inside the coil portion. The biasing member 34 biases the holder 33 upward with respect to the upper guide member 24. In other words, the biasing member 34 biases the holder 33 in a retracting direction in which the punching blade 31 moves away from the sheet S conveyed along the sheet conveyance path Rs.

[0039] The eccentric cam 35 is disposed above the holder 33. The eccentric cam 35 is fixed to the shaft 23. The eccentric cam 35 has a cam portion 35a and a shaft portion 35b.

[0040] The cam portion 35a contacts the upper surface of the holder 33 from above. The cam portion 35a is formed in a circular disk shape when viewed in the axial direction of the shaft 23 (sheet width direction Dw). The holder 33 contacts the outer peripheral portion of the cam portion 35a having a disk shape. The shaft portion 35b is disposed at a position eccentric from the center of the circular cam portion 35a and is formed in a cylindrical shape extending along the axial direction of the shaft 23. The shaft 23 is inserted into and fixed within the shaft portion 35b.

[0041] The eccentric cam 35 obtains power from the punching motor 21 and rotates about the axis of the shaft 23 together with the shaft 23. At this time, the eccentric cam 35 contacts the holder 33 and rotates against the biasing force of the biasing member 34. Then, the eccentric cam 35 moves the holder 33 in the punching direction in which the punching blade 31 approaches the sheet S conveyed along the sheet conveyance path Rs.

[0042] The cam cover 36 is attached above the holder 33 and covers the eccentric cam 35. The cam cover 36 is formed in an arc shape when viewed in the axial direction of the shaft 23 (sheet width direction Dw). The upper end portion of the inner periphery of the cam cover 36 is adjacent to the outer peripheral portion of the cam portion 35a.

[0043] When pulling up the punching blade 31 after the completion of the punching process, the eccentric cam 35 rotates such that the major axis portion moves upward while the outer peripheral portion slides along the inner peripheral surface of the cam cover 36. That is, the cam cover 36 assists the movement of the eccentric cam 35 when pushing up the holder 33 (punching blade 31) by the biasing force of the biasing member 34.

[0044] As shown in FIGS. 4 and 5, when the major axis portion 35c of the eccentric cam 35 is located above the shaft 23, the holder 33 is biased in the retracting direction (upward direction) away from the sheet S conveyed along the sheet conveyance path Rs by the action of the biasing member 34, and the punching blade 31 is disposed at the retracted position.

[0045] When the eccentric cam 35 rotates from the state shown in FIGS. 4 and 5, the eccentric cam 35 rotates so as to push down the holder 33 against the biasing force of the biasing member 34. The eccentric cam 35 moves the holder 33 in the punching direction in which the punching blade 31 approaches the sheet S conveyed along the sheet conveyance path Rs. The punching blade 31 contacts the sheet S and further forms a hole in the sheet S by being pushed down.

[0046] Then, as shown in FIGS. 7 and 8, when the major axis portion 35c of the eccentric cam 35 reaches the lowest position, the punching blade 31 is disposed at the punching completion position, and the punching process for the sheet S is completed.

[0047] As shown in FIGS. 7 and 8, when moving the holder 33 in the punching direction, the eccentric cam 35 passes through the side of the punching guide 32 so as to overlap the punching guide 32 when viewed from the rotational axis direction (sheet width direction Dw) of the eccentric cam 35. In other words, as shown in FIG. 8, when viewed from the sheet width direction Dw, the cam portion 35a of the eccentric cam 35 is located outside the punching guide 32 in the sheet width direction Dw, and rotates around the axis of the eccentric cam 35 at this position.

[0048] According to the above configuration, the eccentric cam 35 is not always positioned in the area on the opposite side (the upper side of the piercing guide 32) that separates the arrangement area of the piercing guide 32 from the piercing position of the sheet S (the location between the through holes 24h and 25h) by the tip of the piercing blade 31 during rotation. As a result, the length of the piercing device 2 along the moving direction (vertical direction) of the piercing blade 31 can be shortened. In other words, the height of the piercing device 2 can be reduced. Therefore, it becomes possible to miniaturize the piercing device 2.

[0049] As shown in FIG. 5, the connecting pin 37 is attached to the holder 33. In this regard, the piercing blade 31 has a connecting hole 31h penetrating in the axial direction of the shaft 23 (sheet width direction Dw) at the upper part. The connecting pin 37 is inserted into the connecting hole 31h to connect the piercing blade 31 and the holder 33. More specifically, the connecting pin 37 protrudes from the piercing blade 31 on one side and the other side of the connecting hole 31h with respect to the axial direction of the shaft 23 (sheet width direction Dw), and is supported by the holder 33 at both ends thereof.

[0050] As shown in FIGS. 5 and 6, the piercing guide 32 has a long hole 32h. The long hole 32h penetrates the cylindrical piercing guide 32 in the axial direction of the shaft 23 (sheet width direction Dw), and its longitudinal direction extends in the moving direction (vertical direction) of the piercing blade 31. The connecting pin 37 is inserted into the long hole 32h.

[0051] The long holes 32h are arranged at two positions facing each other in the axial direction of the shaft 23 (sheet width direction Dw). More specifically, the connecting pin 37 is inserted into the long hole 32h on each of one side and the other side of the piercing blade 31 with respect to the axial direction of the shaft 23 (sheet width direction Dw).

[0052] According to the above configuration, the piercing blade 31 arranged inside the cylindrical piercing guide 32 can be moved integrally with the holder 33. As a result, the piercing blade 31 can be easily reciprocated in the vertical direction, and a smooth piercing process can be realized.

[0053] Further, as shown in FIGS. 3 and 5, the eccentric cam 35 has two cam portions 35a. Each of the two cam portions 35a is formed in a circular identical shape when viewed from the axial direction of the shaft 23 (sheet width direction Dw), and they are arranged in parallel with a space therebetween in the axial direction. The shaft portion 35b connects the two cam portions 35a.

[0054] The two cam portions 35a contact the holder 33 at the same outer peripheral end during their rotation with respect to each other. For example, as shown in FIGS. 4 and 5, both of the two cam portions 35a contact the holder 33 at the minor diameter portion 35d when the holder 33 is at the highest position, and contact the holder 33 at the major diameter portion 35c when the holder 33 is at the lowest position as shown in FIGS. 7 and 8.

[0055] The punching guide 32 is arranged to be located between the two cam portions 35a in the rotational axis direction of the eccentric cam 35 (sheet width direction Dw) as shown in FIGS. 5 and 8. When the holder 33 moves in the punching direction, the two cam portions 35a pass by the side of the punching guide 32 so as to overlap the punching guide 32 when viewed from the rotational axis direction of the eccentric cam 35 (sheet width direction Dw).

[0056] According to the above configuration, a force for pushing down the holder 33 can be applied to the holder 33 on each of one side and the other side of the punching blade 31 with respect to the axial direction of the shaft 23 (sheet width direction Dw). Thereby, the punching blade 31 can be reciprocated in the vertical direction linearly along the extending direction of the punching guide 32. Therefore, rattling during the movement of the punching blade 31 can be suppressed, and a smooth punching process can be realized.

[0057] As described above, the embodiments of the present invention have been explained, but the scope of the present invention is not limited thereto, and various modifications can be made and implemented without departing from the gist of the invention.

[0058] For example, in the above embodiment, the image forming apparatus 200 is assumed to be an image forming apparatus for monochrome printing, but it is not necessarily limited to such a model. The image forming apparatus may be, for example, an image forming apparatus for color printing.

Industrial Applicability

[0059] The present invention can be used in a punching device and a sheet post-processing device.

Explanation of Signs

[0060] 1 Sheet post-processing device 2 Punching device 21 Punching motor 22 Rotation detection unit 23 Shaft 24 Upper guide member 25 Lower guide member 30 Punching part 31 Punching blade 31e Blade tip 31h Connection hole 32 Punching guide 32h Long hole 33 Holder 34 Biasing member 35 Eccentric cam 35a Cam part 35b Shaft part 35c Major axis part 36 Cam cover 37 Connection pin S Sheet

Claims

1. A punching blade for forming a hole in a sheet, a holder for holding the punching blade, a biasing member for biasing the holder in a retracting direction in which the punching blade moves away from the sheet, an eccentric cam that contacts the holder and rotates against the biasing force of the biasing member to move the holder in a punching direction in which the punching blade approaches the sheet, a punching guide that extends in the moving direction of the punching blade with respect to the sheet and guides the movement of the punching blade, comprising: The punching device is characterized in that when the eccentric cam moves the holder in the punching direction, the eccentric cam passes by the side of the punching guide so as to overlap the punching guide when viewed from the direction of the rotation axis of the eccentric cam.

2. comprising a connecting pin connecting the punching blade and the holder, The punching device according to claim 1, wherein the punching guide has a long hole that extends in the moving direction of the punching blade and into which the connecting pin is inserted.

3. The eccentric cam has: two cam portions of the same shape that are arranged in parallel at intervals in the direction of the rotation axis and contact the holder at the same outer peripheral end during their respective rotations, a shaft portion connecting the two cam portions, The punching device according to claim 1, wherein the punching guide is arranged to be positioned between the two cam portions in the direction of the rotation axis.

4. A sheet post-processing device, characterized by comprising the punching device according to any one of claims 1 to 3. ​

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