Post-processing device, image forming system, disposal timing determination method, and disposal timing determination program

Abstract

To appropriately detect the upper limit of storage capacity while suppressing an increase in size. [Solution] The post-processing device includes a punching mechanism that performs a punching operation to cut a portion from the recording medium, a storage unit that stores the cut portion cut from the recording medium, a detection unit 61 that detects a stacking event in which the height of a stack formed by multiple cut portions falling from the punching mechanism into the storage unit reaches a predetermined height, and an upper limit determination unit 63 that determines whether the amount of multiple cut portions stored in the storage unit is at the upper limit based on the number of consecutive stacking events detected by the detection unit at predetermined timings.

Description

Technical Field

[0001] The present invention relates to a post-processing device, an image-forming system, a method for determining the disposal timing, and a disposal timing determination program, and more particularly to a post-processing device having a function of punching a recording medium, an image-forming system including the post-processing device, a method for determining the disposal timing executed by the post-processing device, and a disposal timing determination program for causing a computer to execute the method for determining the disposal timing.

Background Art

[0002] An image-forming device represented by an MFP (Multi Function Peripheral) is connected to a post-processing device that post-processes a recording medium on which an image has been formed. The post-processing executed by the post-processing device includes a punching process for punching the recording medium. The post-processing device includes a storage container for storing chips cut from the recording medium by the punching process. Since the capacity of the storage container has an upper limit, it is required to detect the timing for discarding the chips stored in the storage container.

[0003] The position where the recording medium is punched is often predetermined, and the chips fall to the same position in the storage container. Therefore, a plurality of chips are stacked, and a mountain-shaped stack is partially formed in the storage container. In the process of forming an image on the recording medium, the recording medium may be curved or electrostatically charged. Due to the electrostatic charge on the chips, the height of the stack tends to increase, and the variation in the height of the upper end of the stack in the storage container becomes large. Therefore, it is difficult to accurately detect that the amount of chips stored in the storage container has reached the upper limit.

[0004] Japanese Patent Publication No. 11-255417 describes a sheet processing device that evenly organizes the chips stored in a container for storing chips punched by a punching mechanism, and includes a punch chip storage and organizing means that vibrates the container. However, the sheet processing device described in Japanese Patent Publication No. 11-255417 has the problem that the punch chip storage and organizing means that vibrates the container must be provided separately from the container, which increases the size of the device. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 11-255417 [Overview of the project] [Problems that the invention aims to solve]

[0006] One of the objectives of this invention is to provide a post-processing device that can appropriately detect the disposal time while suppressing an increase in the size of the device.

[0007] Another object of this invention is to provide an image forming system that can appropriately detect the disposal time while suppressing an increase in the size of the post-processing device.

[0008] Another object of this invention is to provide a method for determining the appropriate disposal time while suppressing an increase in the size of the post-processing equipment.

[0009] Another object of this invention is to provide a disposal timing determination program that can appropriately detect the disposal timing while suppressing an increase in the size of the post-processing device. [Means for solving the problem]

[0010] According to one aspect of this invention, the post-processing device includes a punching mechanism that performs a punching operation to cut off a portion from a recording medium, a storage unit that stores the cut portion cut off from the recording medium, a detection unit that detects a stacking event in which the height of a stack of multiple cut portions that fall from the punching mechanism into the storage unit reaches a predetermined height, and a disposal time determination unit that determines whether or not it is time to discard the multiple cut portions stored in the storage unit based on the number of consecutive stacking events detected by the detection unit at predetermined timings.

[0011] According to another aspect of this invention, the image forming system comprises the above-mentioned post-processing device and an image forming apparatus, the image forming apparatus comprising an image forming unit that forms an image on a recording medium, and the predetermined timing is after the image forming apparatus has started a predetermined operation.

[0012] According to yet another aspect of this invention, a method for determining the disposal time is a method for determining the disposal time performed by a post-processing device, the post-processing device comprising: a punching mechanism that performs a punching operation to cut off a portion from a recording medium; a storage unit that stores the cut portion cut off from the recording medium; and a detection unit that detects a stacking event in which the height of a stack of multiple cut portions that fall from the punching mechanism into the storage unit reaches a predetermined height, the method comprising: a detection step of controlling the detection unit to detect the stacking event at a predetermined timing; and a disposal time determination step of determining whether the amount of multiple cut portions stored in the storage unit is at its upper limit based on the number of consecutive stacking events detected in the detection step.

[0013] According to yet another aspect of this invention, the disposal timing determination program is a disposal timing determination program executed by a computer that controls a post-processing device, wherein the post-processing device comprises a punching mechanism that performs a punching operation to cut a portion from a recording medium, a storage unit that stores the cut portion cut from the recording medium, and a detection unit that detects a stacking event in which the height of a stack of multiple cut portions that fall from the punching mechanism into the storage unit reaches a predetermined height, and includes a detection step of controlling the detection unit to detect the stacking event at a predetermined timing, and a disposal timing determination step of determining the disposal timing of the multiple cut portions stored in the storage unit based on the number of consecutive stacking events detected in the detection step. [Brief explanation of the drawing]

[0014] [Figure 1] This figure shows an overall overview of an image forming system in one embodiment of the present invention. [Figure 2] This is a schematic cross-sectional view illustrating an example of the internal structure of an MFP. [Figure 3] This is a perspective view showing the appearance of the post-processing device. [Figure 4] This is a diagram showing the internal configuration of the post-processing device. [Figure 5] This is a left side view of the punch unit. [Figure 6] This is a perspective view of the containment container. [Figure 7] This is a cross-sectional view of the containment container. [Figure 8] This block diagram shows an overview of the hardware configuration of the MFP in this embodiment. [Figure 9] This block diagram shows an example of an overview of the hardware configuration of the control unit included in the post-processing device in this embodiment. [Figure 10] This block diagram shows an example of the functions of the CPU included in the post-processing device in this embodiment. [Figure 11] This flowchart shows an example of the process for determining when to discard an item. [Figure 12] This flowchart shows an example of the timing detection process flow. [Figure 13] It is a diagram showing an example of experimental data. [Figure 14] It is a diagram showing a part of the experimental data in FIG. 13.

Embodiments for Carrying out the Invention

[0015] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same parts are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed descriptions thereof will not be repeated.

[0016] FIG. 1 is a diagram showing an overall overview of an image forming system in one embodiment of the present invention. In some of the drawings after FIG. 1, arrows indicating the X direction, Y direction, and Z direction that are orthogonal to each other are attached to clarify the positional relationship. The X direction and the Y direction are orthogonal to each other in the horizontal plane, and the Z direction corresponds to the vertical direction. Also, in the following description, in the X direction, the direction in which the arrow points is called the right direction, and the opposite direction is called the left direction. Also, in the Y direction, the direction in which the arrow points is called the front direction, and the opposite direction is called the rear direction.

[0017] Referring to FIG. 1, the image forming system 1 includes an MFP (Multi Function Peripheral) 100 and a post-processing device 200. The MFP 100 functions as an image forming device and forms an image on a recording medium based on image data. The MFP 100 can form an image on any of a plurality of types of recording media as the recording medium to be imaged. The recording medium includes, in addition to paper such as paper, an OHP (Overhead projector) sheet, cloth, and the like. Also, in the following description, unless otherwise specified, the case where the recording medium is paper will be described as an example.

[0018] The MFP100 includes an automatic document transporter 120, a document reading unit 130, an image forming unit 140, and a paper feed unit 150. The automatic document transporter 120 transports the document to the document reading unit 130. The document reading unit 130 optically reads the image formed on the document and outputs the image data. The paper feed unit 150 supplies paper to the image forming unit 140. The image forming unit 140 forms an image of the image data on the paper. The image data that the image forming unit 140 targets for image formation includes image data output by the document reading unit 130 after reading the document, and image data received from an external personal computer (PC). The operation panel 160 is the user interface.

[0019] The post-processing device 200 is supplied with paper on which images have been formed from the MFP 100. The post-processing device 200 includes a punch unit 250 (see Figure 4) that performs a punching operation to create punch holes. The punching operation is the operation of perforating predetermined positions on the paper. The post-processing device 200 also has a stapling mechanism that performs a stapling operation to drive staples into multiple sheets of paper. The post-processing device 200 also has a transport mechanism that performs a sorting operation to rearrange and discharge one or more sheets on which images have been formed by the MFP 100. The post-processing device 200 may also have mechanisms that perform a bending operation to fold the paper and a cutting operation to cut a part of the paper.

[0020] Figure 2 is a schematic cross-sectional view showing an example of the internal configuration of an MFP. In Figure 2, the image forming unit 140 and the paper feeding unit 150 of the MFP 100 are shown. Referring to Figures 1 and 2, the image forming unit 140 forms an image on paper or the like based on the image data output by the document reading unit 130 after reading the document. The image forming unit 140 includes image forming units 20Y, 20M, 20C, and 20K for yellow, magenta, cyan, and black, respectively. Here, "Y", "M", "C", and "K" represent yellow, magenta, cyan, and black, respectively. An image is formed when at least one of the image forming units 20Y, 20M, 20C, and 20K is in operation. When all of the image forming units 20Y, 20M, 20C, and 20K are in operation, a full-color image is formed. Image forming units 20Y, 20M, 20C, and 20K are each inputted with print data for yellow, magenta, cyan, and black, respectively. Since image forming units 20Y, 20M, 20C, and 20K differ only in the color of toner they handle, this explanation will focus on image forming unit 20Y, which is used to form yellow images.

[0021] The image forming unit 20Y comprises a photoreceptor drum 23Y, which is an image carrier, a charging roller 22Y, an exposure device 21Y, a developer 24Y, a primary transfer roller 25Y, a drum cleaning blade 27Y, and a toner bottle 40Y. The charging roller 22Y, exposure device 21Y, developer 24Y, primary transfer roller 25Y, and drum cleaning blade 27Y are arranged sequentially around the photoreceptor drum 23Y along the rotational direction of the photoreceptor drum 23Y.

[0022] The charging roller 22Y uniformly charges the surface of the photoreceptor drum 23Y. The exposure device 21Y receives yellow printing data and exposes the photoreceptor drum 23Y according to the printing data. The primary transfer roller 25Y transfers the toner image formed on the photoreceptor drum 23Y onto the intermediate transfer belt 30, which is the image carrier, by the action of an electric field force. The drum cleaning blade 27Y removes any remaining toner from the photoreceptor drum 23Y.

[0023] The photoreceptor drum 23Y is charged by the charging roller 22Y, and then irradiated with laser light emitted by the exposure device 21Y. The exposure device 21Y exposes the image-corresponding portion of the surface of the photoreceptor drum 23Y. This forms an electrostatic latent image on the photoreceptor drum 23Y. Subsequently, the developer 24Y develops the electrostatic latent image formed on the photoreceptor drum 23Y with charged toner. Specifically, toner is placed on the electrostatic latent image formed on the photoreceptor drum 23Y by the action of an electric field force, thereby forming a toner image on the photoreceptor drum 23Y. The toner image formed on the photoreceptor drum 23Y is transferred onto the intermediate transfer belt 30, which is an image carrier, by the action of an electric field force using the primary transfer roller 25Y. Toner that remains on the photoreceptor drum 23Y without being transferred is removed from the photoreceptor drum 23Y by the drum cleaning blade 27Y.

[0024] Toner is supplied to the developer unit 24Y from a toner bottle 40Y. The toner bottle 40Y is cylindrical in shape, extending in one direction, with an opening that opens downwards at one end. The toner bottle 40Y has a spiral-shaped protrusion on its inner surface. The toner contained inside the toner bottle 40Y is transported in one direction as the toner bottle 40Y rotates, falls out through the opening, and is supplied to the developer unit 24Y. The amount of toner supplied is adjusted by changing the rotation speed of the toner bottle 40Y.

[0025] Meanwhile, the intermediate transfer belt 30 is suspended by the drive roller 33 and the driven roller 34 to prevent slack. When the drive roller 33 rotates counterclockwise in Figure 2, the intermediate transfer belt 30 rotates counterclockwise in the figure at a predetermined speed. As the intermediate transfer belt 30 rotates, the driven roller 34 rotates counterclockwise.

[0026] As a result, the image forming units 20Y, 20M, 20C, and 20K sequentially transfer toner images onto the intermediate transfer belt 30. The timing at which each of the image forming units 20Y, 20M, 20C, and 20K transfers toner images onto the intermediate transfer belt 30 is adjusted based on the detection of reference marks attached to the intermediate transfer belt 30. As a result, yellow, magenta, cyan, and black toner images are superimposed onto the intermediate transfer belt 30.

[0027] The toner image formed on the intermediate transfer belt 30 is transferred to the paper by the action of an electric field force by the secondary transfer roller 26, which is a transfer member. The paper, which is transported by the timing roller 31, is transported to the nip section where the intermediate transfer belt 30 and the secondary transfer roller 26 come into contact. The paper on which the toner image has been transferred is transported to the fuser roller 32, where it is heated and pressurized. As a result, the toner melts and is fixed to the paper.

[0028] A belt cleaning blade 28 is provided upstream of the image forming unit 20Y of the intermediate transfer belt 30. The belt cleaning blade 28 removes toner that remains on the intermediate transfer belt 30 without being transferred to the paper.

[0029] When forming a full-color image, the MFP100 drives all four image forming units 20Y, 20M, 20C, and 20K. However, when forming a monochrome image, it drives only one of the four image forming units 20Y, 20M, 20C, and 20K. It is also possible to form an image by combining two or more of the 20Y, 20M, 20C, and 20K image forming units. Here, we will describe an example in which the MFP100 employs a tandem system equipped with image forming units 20Y, 20M, 20C, and 20K that form each of the four toners on the paper. However, the MFP100 may also employ a four-cycle system in which a single photoreceptor drum transfers the four toners sequentially onto the paper.

[0030] The paper feeding unit 150 supplies paper to the image forming unit 140. The paper feeding unit 150 is equipped with paper feed cassettes 35 and 35A. Paper of different sizes is set in the paper feed cassettes 35 and 35A, respectively. The paper stored in the paper feed cassettes 35 and 35A is supplied to the transport path by the ejection rollers 36 and 36A attached to the paper feed cassettes 35 and 35A, respectively, and is then sent to the timing roller 31 by the paper feed roller 37.

[0031] Inside the MFP100, a main transport path 11 and a reversal path 21 are formed, indicated by thick dotted lines. The main transport path 11 and the reversal path 21 are the paths through which the paper passes. The main transport path 11 includes an upper end 12 located above the image forming unit 140 and a lower end 13 on the opposite side of the upper end 12, and extends from the lower end 13 to the upper end 12. The lower end 13 constitutes an inlet for receiving paper from the paper feeding unit 150, and the upper end 12 constitutes an outlet for discharging the image-formed paper to the post-processing device 200. In the main transport path 11, the transport direction in which the paper is transported is from the lower end 13 toward the upper end 12.

[0032] The main transport path 11 connects at its lower end 13 to the transport paths leading to the paper feed cassettes 35 and 35A, respectively. The main transport path 11 connects to the reversal path 41 at a branching point 15 and a merging point 14 located between the upper end 12 and the lower end 13. A switching claw for switching the transport path is provided at the branching point 15.

[0033] The main transport path 11 includes a first main section path 11a extending from the lower end 13 to the confluence point 14, a second main section path 11b extending from the confluence point 14 to the branching point 15, and a third main section path 11c extending from the branching point 15 to the upper end 12. In the second main section path 11b, a timing roller 31, a secondary transfer roller 26, and a fixing roller 32 are arranged in this order at intervals. In the third main section path 11c, a plurality of discharge rollers 38 are arranged.

[0034] The reversal path 41 has a reversal lower limit point 42 and a reversal branching point 43. The reversal branching point 43 is provided with a switching claw for switching the transport path. The reversal path 41 includes a first reversal section path 41a extending from branching point 15 to reversal branching point 43, a second reversal section path 41b extending from reversal branching point 43 to reversal lower limit point 42, and a third reversal section path 41c extending from reversal branching point 43 to merging point 14. A reversal roller 39 is located in the second reversal section path 41b.

[0035] In single-sided printing, where an image is formed on the surface of the paper, the paper transported from the paper feed cassettes 35 and 35A is received at the lower end 13 of the main transport path 11 and transported to the post-processing device 200 via the first main section path 11a, the second main section path 11b, and the third main section path 11c. As the paper passes through the second main section path 11b, an image is formed on its surface by the image forming unit 140.

[0036] In double-sided printing, where images are formed on both sides of the paper, the paper transported from the paper feed cassettes 35 and 35A is received at the lower end 13 of the main transport path 11 and transported through the first main section path 11a to the second main section path 11b. As the paper passes through the second main section path 11b, an image is formed on its surface by the image forming unit 140. Here, the surface on which the image is formed is the surface opposite to the surface in contact with the secondary transfer roller 26. After the image is formed on its surface, the paper passes through the fuser roller 32 and then enters the first reversal section path 41a from the branching point 15. A switching claw provided at the branching point 15 acts, causing the paper to enter the first reversal section path 41a. Here, the leading edge of the paper in the transport direction while the image is being formed on the surface of the paper is called the upper end, and the end opposite the upper end is called the lower end. Therefore, images are formed sequentially on the surface of the paper in the direction from the upper end to the lower end. In this embodiment, the case in which the image formed on the surface of the paper is formed on the paper from the top edge to the bottom edge will be described as an example.

[0037] Paper entering the first reversal section path 41a passes through the reversal branching point 43 and enters the second reversal section path 41b. As paper passes through the first reversal section path 41a, its upper end is the leading edge in the transport direction. While passing through the second reversal section path 41b, the paper is transported by the reversal roller 39. The reversal roller 39 reverses the direction of rotation of the paper before the trailing edge passes the reversal branching point 43 and reaches the reversal roller 39. After the transport direction is reversed by the reversal roller 39, the lower end of the paper is the leading edge in the transport direction.

[0038] The paper transported by the reversing roller 39 enters the third reversing section path 41c from the reversing branching point 43. A switching claw provided at the reversing branching point 43 acts, causing the paper to enter the third reversing section path 41c.

[0039] The paper being transported in the third reversal section path 41c enters the second main section path 11b at the confluence point 14. As the paper passes through the second main section path 11b, an image is formed on its back surface by the image forming unit 140. After the image is formed on the back surface of the paper, it passes through the fixing roller 32, enters the third main section path 11c from the branching point 15, and is transported to the post-processing device 200 via the third main section path 11c. The paper entering the second main section path 11b from the third reversal section path 41c has its lower end as the leading edge in the transport direction, and its back surface faces away from the secondary transfer roller 26. Therefore, an image is formed sequentially on the back surface of the paper from its lower end toward its upper end. Also, the image formed on the back surface of the paper is formed on the paper from the lower end of the image toward its upper end.

[0040] Figure 3 is a perspective view showing the external appearance of the post-processing device. Referring to Figure 3, the post-processing device 200 has a sub-tray 203 and three main trays 205, 205A, and 205B located on the right side of the main case 201, and a manual stapling unit 275 located on the front.

[0041] The manual stapling unit 275 has an insertion slot 276 for the user to insert multiple stacks of paper from the outside, and a paper detection sensor 277. A notch is provided extending from the insertion slot 276 into the inside of the main body case 201, allowing the user to insert multiple stacks of paper from the insertion slot 276 into the notch. The paper detection sensor 277 is located in the notch extending from the insertion slot 276 inside the main body case 201. The paper detection sensor 277 is a through-type optical sensor. The paper detection sensor 277 detects multiple stacks of paper inserted from the insertion slot 276 into the notch. A stapling mechanism 271 (see Figure 4) is provided inside the main body case 201, and when the stapling mechanism 271 performs a stapling operation, staples are driven into the multiple stacks of paper. Note that the paper detection sensor 277 is not limited to a through-type optical sensor; an ultrasonic sensor, a reflective optical sensor, a touch sensor, etc., may also be used as long as they can detect multiple stacks of paper. Alternatively, the paper detection sensor 277 may be a lever whose tilt changes due to a stack of papers inserted into the notched section from the insertion slot 276, and a contact switch that detects the tilt of the lever.

[0042] Furthermore, in this embodiment, an example is described in which the stapling mechanism 271 performs a stapling operation in response to the detection of multiple stacks of paper by the paper detection sensor 277. However, the stapling mechanism 271 may also perform a stapling operation in response to user input. User input may be, for example, pressing a button switch. The button switch may be located near the manual stapling section 275 of the main body case 201, or it may be located on the main body of the MFP100. In this case, the paper detection sensor 277 is not required.

[0043] Figure 4 shows the internal configuration of the post-processing device. Referring to Figure 4, the post-processing device 200 comprises a transport mechanism 210, a punch unit 250, a staple unit 270, and a control unit 230. The transport mechanism 210 includes a pair of registration rollers 211, a pair of intermediate rollers 213, a switch 214, a pair of sub-discharge rollers 215, a pair of storage rollers 217, a paddle 219, and a pair of main discharge rollers 221.

[0044] The transport mechanism 210 transports paper received from the MFP 100 along transport paths R1, R2, and R3. Transport path R1 extends from the connecting port 209, which receives paper discharged from the MFP 100, to the branching point 212. Transport path R2 extends from the branching point 212 to the sub-tray 203 via the sub-discharge roller pair 215. Transport path R3 extends from the branching point 212 to the main tray 205 via the receiving roller pair 217. A switch 214 is located at the branching point 212. The switch 214 switches between transport path R2 and transport path R3.

[0045] The paper output from the MFP100 is received at the connecting port 209 and transported along the transport path R1 by the registration roller pair 211 and the intermediate roller pair 213. Within the transport path R1, the punch unit 250 is positioned between the registration roller pair 211 and the intermediate roller pair 213.

[0046] If the switch 214 selects transport path R2, the paper enters transport path R2 and is then transported along transport path R2 by the sub-discharge roller pair 215 and discharged into the sub-tray 203. If the switch 214 selects transport path R3, the paper enters transport path R3 and is then transported along transport path R2 by the containment roller pair 217 and reaches the main discharge roller pair 221.

[0047] The main discharge roller pair 221 includes an upper roller 221a and a lower roller 221b. The upper roller 221a and lower roller 221b are supported by the main case 201 so that the upper roller 221a can move vertically relative to the lower roller 221b. In normal modes other than online stapling mode, the main discharge roller pair 221 rotates with the upper roller 221a in contact with the lower roller 221b. Paper transported from the storage roller pair 217 is discharged into one of the main trays 205, 205A, or 205B.

[0048] On the other hand, in online stapling mode, the rotation of the main discharge roller pair 221 is stopped when the upper roller 221a is separated from the lower roller 221b. When the upper roller 221a is separated from the lower roller 221b, the paper is interposed between the upper roller 221a and the lower roller 221b. When the rear end of the paper in the transport direction passes the storage roller pair 217, the paper is no longer constrained by either the storage roller pair 217 or the main discharge roller pair 221 and becomes free. The paddle 219 rotates in conjunction with the timing when the rear end of the paper in the transport direction passes the storage roller pair 217, and the tip of the paddle 219 strikes the top surface of the paper. This applies a force to the paper in the diagonal lower right direction shown in the figure, and the paper is transported to the stapling unit 270.

[0049] The stapling unit 270 includes a stapling mechanism 271, a loading tray 272, a locking part 273, and alignment plates 274L,R. The paddle 219 rotates in time with the moment the rear end of the paper being transported by the storage roller pair 217 passes the storage roller pair 217, forcing the paper onto the loading tray 272. The loading tray 272 is inclined such that the end furthest from the main discharge roller pair 221 is positioned lower than the end closer to the main discharge roller pair 221. The paper falling onto the loading tray 272 descends along the inclined surface of the loading tray 272 and stops when it hits the locking part 273 located at the lower end of the loading tray 272.

[0050] With multiple stacks of paper loaded onto the loading tray 272, the stapling mechanism 271 drives staples into the stacks of paper. Then, the upper roller 221a of the main discharge roller pair 221 rotates in contact with the lower roller 221b, and the multiple stacks of paper loaded onto the loading tray 207 are discharged into one of the main trays 205, 205A, or 205B.

[0051] The transport mechanism 210 performs a sorting operation to discharge multiple sheets of paper or multiple stacks of paper into a designated tray determined from among the main trays 205, 205A, and 205B. The designated tray is selected by the user from among the main trays 205, 205A, and 205B. The main trays 205, 205A, and 205B are movable in the vertical direction. The transport mechanism 210 moves the main trays 205, 205A, and 205B in the vertical direction so that the designated tray is directly below the main discharge roller pair 221. The sheets of paper or multiple stacks of paper discharged from the main discharge roller pair 221 are then discharged into the designated tray among the main trays 205, 205A, and 205B.

[0052] Figure 5 is a left side view of the punch unit. Figure 5 is a view of the punch unit 250 from left to right. Referring to Figures 4 and 5, the punch unit 250 comprises a punch mechanism 260 and a storage container 251. The punch mechanism 260 and the storage container 251 are arranged vertically. The storage container 251 is located below the punch mechanism 260. Paper conveyed by the registration roller pair 211 is positioned at a predetermined position relative to the punch mechanism 260 by the registration roller pair 211 and the intermediate roller pair 213. The registration roller pair 211 and the intermediate roller pair 213 position the paper relative to the punch unit 250 by stopping their rotation while gripping the paper. With the registration roller pair 211 and the intermediate roller pair 213 positioning the paper, the punch mechanism 260 performs a punching operation.

[0053] The punch mechanism 260 has a punch upper part 261 and an opposing plate 263. The punch upper part 261 and the opposing plate 263 are positioned opposite each other across the sheet transport path R1. The punch upper part 261 is positioned above the transport path R1, and the opposing plate 263 is positioned below the transport path R1.

[0054] The upper part of the punch 261 includes a plurality of punch shafts 265, a cam plate 255, and a drive motor 267. Each of the plurality of punch shafts 265 is cylindrical in shape, with a punch blade formed at its lower end. Each of the plurality of punch shafts 265 is connected to the punch mechanism 260 in a position where its axis is parallel to the Z direction and it is capable of reciprocating in the Z direction. In this embodiment, four punch shafts 265 are installed. The configuration of all four punch shafts 265 is the same. A sliding member 265A extending perpendicular to the axis is fixed to the punch shaft 265. The sliding member 265A is cylindrical in shape, and the axis of rotational symmetry of the sliding member 265A is perpendicular to the axis of the punch shaft 265.

[0055] The cam plate 255 has a cam groove formed on it. The drive motor 267 moves the cam plate 255 parallel to the Y direction. The cam plate 255 is a flat plate having a reference plane parallel to the Z direction. The cam plate 255 has a cam groove 255A formed on it perpendicular to the reference plane. The sliding member 265A of the punch shaft 265 is inserted into the cam groove 255A formed on the cam plate 255. The width of the cam groove 255A in the Z direction is the same as or slightly larger than the outer diameter of the sliding member 265A. The cam plate 255 is mounted on the punch mechanism 260 in a state where it can reciprocate along the Y direction. The cam plate 255 is connected to the drive motor 267 via a rack and pinion mechanism. The cam plate 255 reciprocates with the drive motor 267 as the driving source. As the cam plate 255 reciprocates along the Y direction, the sliding member 265A of the punch shaft 265 slides within the cam groove 255A. This causes the punch shaft 265 to reciprocate in the Z direction. As the punch shaft 265 descends, the opposing plate 263 rises to support the paper. While the punch shaft 265 descends and the opposing plate 263 rises, the punch shaft 265 penetrates the through hole 263A formed in the opposing plate 263. As a result, a predetermined portion of the paper is cut off, and the cut portion falls downward as paper shavings.

[0056] The containment container 251 is a rectangular box with an open top. The containment container 251 receives and stores the chips that fall from the punching mechanism 260. The containment container 251 is equipped with a photoelectric sensor 253. The photoelectric sensor 253 includes a light-emitting unit 253A that emits light and a light-receiving unit 253B that receives light. In Figure 5, the laser beam is shown by a dashed line. The light-emitting unit 253A and the light-receiving unit 253B are positioned at the top inside the containment container 251. When chips are contained in the containment container 251, a pile of chips is formed, which is a stack of chips in the shape of a mountain. If the height of the pile of chips exceeds the height at which the photoelectric sensor 253 is positioned, the laser beam emitted by the light-emitting unit 253A is blocked by the pile of chips. Therefore, by detecting the state in which the light-receiving unit 253B receives light, it is detected that the height of the pile of chips has reached a predetermined height.

[0057] Figure 6 is a perspective view of the storage container. Figure 7 is a cross-sectional view of the storage container. Referring to Figures 6 and 7, the scraps are indicated by black circles. The positions of each of the multiple punch shafts 265 of the punch mechanism 260 are fixed in the Y and X directions. Therefore, when the same punch shaft 265 punches multiple sheets of paper, the scraps fall to the same position in the storage container 251. As a result, there is a high probability that multiple scraps will accumulate and form a mountain-shaped stack. Figure 7 shows an example where two stacks are formed. The laser light emitted by the light-emitting part 253A of the photoelectric sensor 253 is blocked by the stack and cannot be received by the light-receiving part 253B. On the other hand, although scraps are accumulated in the parts other than the two stacks, their upper surface is considerably lower than the position where the photoelectric sensor 253 is installed. As a result, the laser light emitted by the light-emitting part 253A of the photoelectric sensor 253 is blocked by the stack while the storage capacity of the storage container 251 remains sufficient.

[0058] Figure 8 is a block diagram illustrating the hardware configuration of the MFP in this embodiment. Referring to Figure 4, the MFP 100 includes a main circuit 110. The MFP 100 is an example of an image forming apparatus. The main circuit 110 includes a CPU 111, a communication interface (I / F) unit 112, a ROM 113, a RAM 114, an EPROM (Erasable Programmable ROM) 115 as a large-capacity storage device, a facsimile unit 116, and an external storage device 117. The CPU 111 is connected to an automatic document transport device 120, a document reading unit 130, an image forming unit 140, a paper feeding unit 150, and an operation panel 160, and controls the entire MFP 100.

[0059] The CPU 111 is connected to the automatic document transport device 120, the document reading unit 130, the image forming unit 140, the paper feeding unit 150, and the operation panel 18, and controls the entire MFP 100.

[0060] ROM 113 stores the program executed by CPU 111, or the data necessary to execute that program. RAM 114 is used as a workspace when CPU 111 executes the program. Furthermore, RAM 114 temporarily stores image data that is continuously sent from document reading unit 130.

[0061] The communication interface unit 112 is an interface for connecting the MFP 100 to a network. The CPU 111 communicates with a computer connected to the network via the communication interface unit 112 and sends and receives data. The communication interface unit 112 also has a serial communication interface and is connected to the post-processing unit 200.

[0062] The facsimile unit 116 is connected to the Public Switched Telephone Network (PSTN) and transmits facsimile data to or receives facsimile data from the PSTN. The facsimile unit 116 stores the received facsimile data in the EPROM 115 or outputs it to the image forming unit 140. The image forming unit 140 prints the facsimile data received by the facsimile unit 116 onto paper. The facsimile unit 116 also converts the data stored in the EPROM 115 into facsimile data and transmits it to a facsimile device connected to the PSTN.

[0063] The control panel 160 is provided on the top surface of the MFP 100 and includes a display unit 161 and an operation unit 163. The display unit 161 is, for example, a liquid crystal display (LCD) or an organic electroluminescence (EL) display, and displays instruction menus for the user, information about acquired image data, etc. The operation unit 163 includes a touch panel and hard keys. The touch panel is provided on the top or bottom surface of the display unit 161, superimposed on the display unit 161. The hard keys are, for example, contact switches. The touch panel detects the position indicated by the user on the display surface of the display unit 161.

[0064] EPROM115 stores the program that the CPU111 will execute, or the data necessary to execute that program. The CPU111 loads the program stored in EPROM115 into RAM114 and executes it.

[0065] The external storage device 117 is fitted with a CD-ROM (Compact Disk-Read Only Memory) 118. The CPU 111 can access the CD-ROM 118 via the external storage device 117. The CPU 111 loads the program recorded on the CD-ROM 118 fitted into the external storage device 117 into the RAM 114 and executes it.

[0066] Figure 9 is a block diagram showing an example of the hardware configuration of the control unit included in the post-processing device in this embodiment. Referring to Figure 9, the control unit 230 included in the post-processing device 200 includes a CPU 231, a ROM 232, a RAM 233, an SSD 234, a communication unit 235, and an external storage device 236.

[0067] The CPU 231 controls the entire post-processing unit 200. The ROM 232 stores the program for the CPU 231 to execute. The RAM 233 is used as the CPU 231's workspace. The SSD 234 is a large-capacity storage device that stores data non-volatilely. A hard disk drive (HDD) may be used instead of the SSD 234.

[0068] The communication unit 235 is an interface for serial communication with an external device. Serial communication is, for example, the USB (Universal Serial Bus) standard. External devices capable of communicating via the USB standard can be connected to the communication unit 235. Here, the communication unit 235 is connected to the communication I / F unit 112 of the MFP 100. The CPU 231 can send and receive data with the CPU 111 of the MFP 100 via the communication unit 235. Furthermore, the communication unit 235 may be connected to an external network such as the Internet.

[0069] The external storage device 236 is controlled by the CPU 231. The external storage device 236 is equipped with a CD-ROM 237 or semiconductor memory. In this embodiment, an example is described in which the CPU 231 executes a program stored in ROM 232. The CPU 231 may also control the external storage device 236 to read a program from the CD-ROM 237, store the read program in RAM 233, and execute it.

[0070] The recording medium for storing programs to be executed by the CPU 231 is not limited to the CD-ROM 237. Instead of the CD-ROM 237, other media such as flexible disks, cassette tapes, HDDs (hard disk drives), optical disks, IC cards, optical cards, and semiconductor memory may be used. Optical disks include MO (Magnetic Optical Disc), MD (Mini Disc), and DVD (Digital Versatile Disc). Semiconductor memory includes mask ROM. Furthermore, a computer connected to the network may write programs to the SSD 234. The CPU 231 may load the programs stored in the SSD 234 into the RAM 233 and execute them. The term "program" here includes not only programs directly executable by the CPU 231, but also source programs, compressed programs, encrypted programs, and the like.

[0071] The CPU 231 further includes a transport control circuit 241, a staple control circuit 242, a punch control circuit 243, a temperature sensor 245, a humidity sensor 246, and a photoelectric sensor 253.

[0072] The transport control circuit 241 controls the transport of paper. Specifically, the transport control circuit 241 is connected to the registration roller pair 211, the intermediate roller pair 213, the sub-discharge roller pair 215, the switch 214, the storage roller pair 217, the paddle 219, and the main discharge roller pair 221, and drives the motors connected to them. In addition, when the sorting function is enabled, the transport control circuit 241 moves the main trays 205, 205A, and 205B up and down.

[0073] The staple control circuit 242 controls the staple unit 270. Specifically, the staple control circuit 242 drives a motor that moves the alignment plate 274, and also drives a motor that moves and staples the staple mechanism 271.

[0074] The punch control circuit 243 controls the punch unit 250. Specifically, the punch control circuit 243 is connected to the drive motor 267. The punch control circuit 243 drives the drive motor 267 to move the cam plate 255.

[0075] The temperature sensor 245 is located in the internal space of the post-processing unit 200 and detects the temperature. The humidity sensor 246 is located in the internal space of the post-processing unit 200 and detects the humidity.

[0076] Figure 10 is a block diagram showing an example of the functions of the CPU in the post-processing device in this embodiment. The functions shown in Figure 10 are realized by the CPU 231 of the post-processing device 200 when the CPU 231 executes a disposal timing determination program stored in the ROM 232, SSD 234, or CD-ROM 237.

[0077] Referring to Figure 10, the CPU 231 of the post-processing device 200 includes a transport control unit 51, a punch control unit 53, a staple control unit 55, an environmental value acquisition unit 57, a timing determination unit 59, a detection unit 61, a disposal timing determination unit 63, a first threshold change unit 65, a second threshold change unit 67, and a notification unit 69.

[0078] The transport control unit 51 controls the transport control circuit 241 to execute the transport operation. The transport control unit 51 switches the paper transport path according to the post-processing instructions input from the MFP 100. If the post-processing instructions include instructions to punch holes, the transport control unit 51 controls the transport control circuit 241 to position the paper at a predetermined position relative to the punch unit 250. The transport control circuit 241 drives the registration roller pair 211 and the intermediate roller pair 213 so that the paper is positioned at a predetermined position in the punch unit 250.

[0079] The punch control unit 53 controls the punch control circuit 243 to punch the paper at the position specified by the post-processing instruction. The punch control circuit 243 drives the drive motor 267 to move one or more of the multiple punch shafts 265 downward, corresponding to the paper position specified by the post-processing instruction, thereby punching one or more cutting portions of the paper. The punch control unit 53 outputs the operating state of the punch unit 250 to the timing determination unit 59. The operating state of the punch unit 250 includes the operating period from the start to the end of the punching operation. The operating period is the period during which the drive motor 267 of the punch unit 250 is operating. The operating state of the punch unit 250 may also include the period during which the punch shafts 265 punch the paper.

[0080] If the post-processing instruction input from the MFP100 includes an instruction to staple the paper, the transport control unit 51 transports the paper to the loading tray 272 and then discharges it to one of the main trays 205, 205A, or 205B. The transport control unit 51 drives the switch 214, the storage roller pair 217, and the paddle 219 via the transport control circuit 241. The transport control circuit 241 drives the switch 214, causing the paper to travel along the transport path R3. The transport control circuit 241 drives the paddle 219, causing the paper to be loaded onto the loading tray 272. The transport control circuit 241 drives motors that move the main trays 205, 205A, and 205B vertically, so that the output tray specified by the post-processing instruction moves to the position corresponding to the main output roller pair 221.

[0081] The transport control unit 51 outputs the paper transport status to the timing determination unit 59. The transport status includes the position of the paper in the transport path and the transport period from the start to the end of the transport process that transports the paper. The transport period is the period during which any of the registration roller pair 211, intermediate roller pair 213, sub-discharge roller pair 215, switch 214, storage roller pair 217, paddle 219, and main discharge roller pair 221 are operating. In addition, the transport period includes the period during which the motors that move the main trays 205, 205A, and 205B in the vertical direction are operating.

[0082] The staple control unit 55 controls the staple control circuit 242 to drive staples into the paper at the positions specified by the post-processing instructions. The staple control circuit 242 drives a motor that moves the alignment plate 274R so that the positions of the multiple sheets of paper loaded on the loading tray 272 are aligned with the loading tray 272. The staple control circuit 242 drives the staple mechanism 271 so that staples are driven into the stack of multiple sheets of paper loaded on the loading tray 272, or into the stack of multiple sheets of paper inserted by the user into the insertion slot 276.

[0083] The staple control unit 55 outputs the operating status of the staple unit 270 to the timing determination unit 59. The operating status of the staple unit 270 includes the operating period from the start to the end of the stapling operation. The operating period is the period during which the drive motor 267 of the staple unit 270 is operating. The operating status of the staple unit 270 includes the period during which the staple mechanism 271 moves, the period during which the staple mechanism 271 performs a stapling operation in which it drives staples into a stack of multiple sheets of paper, and the period during which the alignment plates 274L and 274R perform an alignment operation in which they align the paper.

[0084] The timing determination unit 59 determines the timing for detecting a stacking event. A stacking event is an event in which the height of a stack formed by multiple chips falling from the punch unit 250 into the storage container 251 reaches a predetermined height. Here, the timing for detecting a stacking event is called the detection timing. In response to determining the detection timing, the timing determination unit 59 outputs a detection instruction to the detection unit 61.

[0085] The timing determination unit 59 determines the detection timing to be a point in time after the punching operation has started. In this case, the timing determination unit 59 determines the detection timing to be a point in time after the operation period of the punching operation has ended. Preferably, the timing determination unit 59 determines the detection timing to be a point in time after a predetermined time has elapsed after the operation period of the punching operation has ended. The timing determination unit 59 may also determine the detection timing to be any point in time during the operation period of the punching operation.

[0086] Furthermore, the timing determination unit 59 determines the detection timing to be a point in time after the stapling operation has started. The stapling operation is an operation in which the stapling control circuit 242 drives the stapling mechanism 271 to position the stapling mechanism 271 and drives staples into a stack of multiple sheets of paper. Here, the timing determination unit 59 determines the detection timing to be a point in time after the operation period of the stapling operation. Preferably, the timing determination unit 59 determines the detection timing to be a point in time after a predetermined time has elapsed after the operation period of the stapling operation. The timing determination unit 59 may also determine the detection timing to be any point in time during the operation period of the stapling operation.

[0087] Furthermore, the timing determination unit 59 determines the detection timing to be a point in time after the alignment operation has started. The alignment operation is an operation in which the staple control circuit 242 drives a motor that moves the alignment plate 274R to align the positions of multiple sheets of paper loaded on the loading tray 272 relative to the loading tray 272. Here, the timing determination unit 59 determines the detection timing to be a point in time after the operation period of the alignment operation. Preferably, the timing determination unit 59 determines the detection timing to be a point in time after a predetermined time has elapsed after the operation period of the alignment operation. The timing determination unit 59 may also determine the detection timing to be any point in time during the operation period of the alignment operation.

[0088] Furthermore, the timing determination unit 59 determines the detection timing to be a point in time after the paper transport has started. Here, the timing determination unit 59 determines the detection timing to be a point in time after the transport operation of transporting the paper has been completed. Preferably, the timing determination unit 59 determines the detection timing to be a point in time after a predetermined time has elapsed after the transport operation. The timing determination unit 59 may also determine the detection timing to be any point in time during the period in which the transport operation is being performed.

[0089] The detection unit 61 detects stacking events in response to a detection instruction input from the timing determination unit 59. The detection unit 61 controls the photoelectric sensor 253 and detects stacking events based on the output of the light receiving unit 253B. The detection unit 61 detects stacking events while the light receiving unit 253B outputs a signal indicating that it is not receiving light emitted from the light emitting unit 253A. The predetermined height is determined by the position of the photoelectric sensor 253 placed in the containment container 251. The detection unit 61 outputs the detection result to the disposal timing determination unit 63.

[0090] The disposal timing determination unit 63 determines the disposal timing of the multiple chips contained in the containment container 251. The disposal timing determination unit 63 counts the number of consecutive detection results from the detection unit 61 indicating that a stacking event has been detected. The disposal timing determination unit 63 compares the counted number with a threshold. If the counted number is equal to or greater than the threshold, the disposal timing determination unit 63 determines that it is time to dispose of the multiple chips contained in the containment container 251. If the counted number is less than the threshold, the disposal timing determination unit 63 determines that it is not time to dispose of the multiple chips contained in the containment container 251. The threshold is a predetermined value and is stored in the SSD 234 in advance. When the disposal timing determination unit 63 determines that it is time to dispose of the multiple chips contained in the containment container 251, it outputs a notification instruction to the notification unit 69.

[0091] The environmental value acquisition unit 57 acquires environmental values. These environmental values ​​include temperature and humidity. The environmental value acquisition unit 57 controls the temperature sensor 245 and acquires the temperature detected by the temperature sensor 245. The environmental value acquisition unit 57 controls the humidity sensor 246 and acquires the humidity detected by the humidity sensor 246. The environmental value acquisition unit 57 outputs the acquired environmental values ​​to the first threshold value changing unit 65.

[0092] The first threshold modification unit 65 modifies the threshold used by the disposal timing determination unit 63 to determine the disposal timing. The first threshold modification unit 65 receives environmental values ​​from the environmental value acquisition unit 57. The first threshold modification unit 65 modifies the threshold based on the environmental values. Multiple chips contained in the containment container 251 may become charged with static electricity. The amount of static electricity charged on the chips is greater when the absolute humidity is low compared to when it is high. Therefore, even if the amount of multiple chips is the same, the laminate formed by them tends to be higher. The first threshold modification unit 65 changes the threshold to a larger value the lower the absolute humidity. The first threshold modification unit 65 modifies the threshold based on temperature and humidity. When the first threshold modification unit 65 modifies the threshold, it outputs the modified threshold to the disposal timing determination unit 63. After receiving the modified threshold from the first threshold modification unit 65, the disposal timing determination unit 63 uses the modified threshold to determine the disposal timing of the multiple chips contained in the containment container 251.

[0093] The second threshold changing unit 67 changes the threshold after power is turned on to the post-processing device 200 or after the outer panel of the post-processing device 200 is opened or closed. Specifically, the second threshold changing unit 67 changes the threshold to a smaller value. After power is turned on or after the outer panel is opened or closed, there is a high probability that the user has already disposed of the chips contained in the containment container 251. Also, there is a high probability that the user is located near the post-processing device 200. In such situations, changing the threshold to a smaller value makes it possible to reliably detect that it is time to dispose of the chips contained in the containment container 251. Furthermore, it is possible to prompt the user to dispose of the cut parts contained in the containment container 251 when the user is located near the post-processing device 200. After a predetermined time has elapsed since power was turned on or after the outer panel of the post-processing device 200 was opened or closed, the second threshold changing unit 67 returns the changed threshold to its original value.

[0094] When the threshold is changed by the second threshold changing unit 67, the disposal timing determination unit 63 uses the changed threshold to determine the disposal timing of the multiple pieces of wood stored in the storage container 251.

[0095] When the disposal timing determination unit 63 outputs a notification instruction, the notification unit 69 notifies the user that it is time to dispose of the chips. The notification unit 69 displays a message on the display unit 161 prompting the user to dispose of the chips contained in the containment container 251. The notification unit 69 sends a command from the communication unit 235 to the MFP 100, causing the message to be displayed on the display unit 161 of the MFP 100. If the post-processing device 200 has a warning lamp, the notification unit 69 may also illuminate the warning lamp. Furthermore, if the post-processing device 200 has a speaker, it may output a warning sound or message from the speaker.

[0096] Figure 11 is a flowchart showing an example of the disposal timing determination process. The disposal timing determination process is performed by the CPU 231 of the post-processing device 200 when the CPU 231 executes a disposal timing determination program stored in the ROM 232, SSD 234, or CD-ROM 237.

[0097] Referring to Figure 11, the CPU 231 of the post-processing unit 200 reads the counter value (step S01) and proceeds to step S02. The counter value indicates the number of times stacking events have been detected consecutively, and is changed in step S05 or step S06, described later, and stored in the SSD 234.

[0098] In step S02, the timing detection process is executed, and the process proceeds to step S03. The details of the timing detection process will be described later, but the timing detection process is the process of detecting the detection timing for detecting stacking events.

[0099] In step S03, the CPU 231 determines whether or not a detection timing has been detected. If a detection timing has been detected, the CPU 231 proceeds to step S04; otherwise, it proceeds to step S09. In step S04, a stacking event is detected. A stacking event is detected when the light receiving unit 253B of the photoelectric sensor 253 does not receive light emitted from the light emitting unit 253A. A stacking event is not detected when the light receiving unit 253B of the photoelectric sensor 253 receives light emitted from the light emitting unit 253A. If a stacking event is detected, the process proceeds to step S05; otherwise, the process proceeds to step S06. In step S06, the counter value is reset, and the process proceeds to step S09. The counter value is set to 0.

[0100] In step S05, the counter value is incremented, and the process proceeds to step S07. In step S07, the counter value is compared with a threshold. If the counter value is greater than or equal to the threshold, the process proceeds to step S08; otherwise, the process proceeds to step S09.

[0101] In step S08, the user is notified, and the process proceeds to step S09. The user is notified that it is time to dispose of the chips. In step S09, it is determined whether the power to the post-processing device 200 has been turned off. If the power is not turned off, the process returns to step S02; if the power has been switched off, the process proceeds to step S10. In step S10, the counter value is stored in the SSD 234, and the process ends.

[0102] Figure 12 is a flowchart showing an example of the timing detection process flow. The timing detection process is executed in step S02 of the disposal timing determination process. Referring to Figure 12, the CPU 231 determines whether the transport operation has finished or not (step S11). If the transport operation has finished, the process proceeds to step S15; otherwise, the process proceeds to step S12.

[0103] In step S12, the CPU 231 determines whether the punching operation has finished. If the punching operation has finished, the process proceeds to step S15; otherwise, the process proceeds to step S12.

[0104] In step S13, the CPU 231 determines whether the stapling operation is complete. If the stapling process is complete, the process proceeds to step S15; otherwise, the process proceeds to step S12.

[0105] In step S14, the CPU 231 determines whether the matching operation has finished. If the matching process is finished, the process proceeds to step S15; otherwise, the process returns to the discard timing determination process. In step S15, it is determined that it is the detection timing, and the process returns to the discard timing determination process.

[0106] Figure 13 shows an example of experimental data. The horizontal axis represents the number of chips punched by the punching operation, and the vertical axis represents the output of the photoelectric sensor 253. The output of the photoelectric sensor 253 is represented by the output voltage of the light receiving unit 253B. The output voltage of the light receiving unit 253B is inversely proportional to the amount of light received. Here, a stacking event is defined as an output voltage of 1.25V or higher of the light receiving unit 253B.

[0107] Figure 14 shows a portion of the experimental data from Figure 13. The horizontal axis shows the portion where the number of chips punched by the punching process is 1300 or more. Multiple stacking events are detected in each of the intervals where the number of chips is between 1400 and 1500, between 1800 and 1700, and above 1700. When the number of chips is less than 1980, detection events are detected, but the number of consecutive detections is less than the threshold. This is because the stack formed by the chips in the state where stacking events are detected collapses due to vibrations applied to the containment container 251, causing stacking events to no longer be detected.

[0108] When the number of chips exceeded 1980, spillage of chips was observed from container 251. While the frequency of detecting stacking events increased particularly in the section where the number of chips exceeded 1900, a threshold can be experimentally determined so that the chips are deemed ready for disposal when the number exceeds 1980.

[0109] <First variation> The timing determination unit 59 may determine the detection timing based on the operating state of the MFP 100. The timing determination unit 59 determines the detection timing to be the time after the paper feeding unit 150 of the MFP 100 has started transporting paper. For example, the timing determination unit 59 determines the detection timing to be the time after the paper feeding unit 150 has transported the paper. Preferably, the timing determination unit 59 determines the detection timing to be a predetermined time after the paper feeding unit 150 has transported the paper. The timing determination unit 59 may determine the detection timing to be any time during the period in which the paper feeding unit 150 transports paper.

[0110] Furthermore, if the job executed by the MFP100 specifies double-sided printing, the paper is reversed by the reversing roller 39. The timing determination unit 59 determines the detection timing to be the time after the reversing roller 39 has reversed. Preferably, the timing determination unit 59 determines the detection timing to be the time after a predetermined period of time has elapsed after the reversing roller 39 has reversed.

[0111] <Second variation> When performing double-sided printing with the MFP100, vibrations occur more frequently, and these vibrations are transmitted to the post-processing unit 200. Therefore, when running a job that specifies double-sided printing on the MFP100, the threshold value may be changed to a smaller value.

[0112] As described above, the post-processing device 200 in this embodiment includes a punching mechanism 260 that performs a punching operation to cut a portion from the paper, a storage container 251 that stores the scraps, which are the cut portions cut from the paper, and a detection unit 61 that detects a stacking event when the height of a stack of scraps reaches a predetermined height. The stack may collapse due to vibration. Before the stack collapses, the stacking event may be detected when the scraps have not yet fully filled the storage container 251. Furthermore, the post-processing device 200 includes a disposal timing determination unit 63 that determines the disposal timing of the multiple scraps stored in the storage container 251 based on the number of consecutive stacking events detected by the detection unit 61 at a predetermined timing. Since the stacking event is detected at a predetermined timing, the stacking event can be detected at a timing when there is a high probability that the stack will collapse. Also, since the disposal timing of the multiple scraps stored in the storage container is determined based on the number of consecutive stacking events, a stacking event detected when the scraps have not yet fully filled the storage container 251 can be treated as a false detection. Therefore, the timing for discarding the chips contained in the container 251 can be appropriately detected. There is no need to provide a separate drive unit to vibrate the container 251.

[0113] Furthermore, the post-processing device 200 detects a lamination event at a predetermined timing even when the punching operation is not performed. Therefore, it is possible to detect a lamination event after the laminate has collapsed due to vibrations caused by operations other than the punching operation.

[0114] Furthermore, the predetermined timing is after the punch mechanism 260 begins the punching operation to cut scraps from the paper. Therefore, the stacking event can be detected after the stack has collapsed due to the vibrations of the punching operation.

[0115] Furthermore, the predetermined timing is after the transport mechanism 210 has started transporting the paper. Therefore, the stacking event can be detected after the stack has collapsed due to the vibrations that occur when the recording medium is transported.

[0116] Furthermore, the predetermined timing is after the alignment plates 274L and 274R begin the alignment operation to align the paper positions on the stacking tray 272. Therefore, the stacking event can be detected after the stack has collapsed due to vibrations generated when the paper positions are aligned.

[0117] Furthermore, the predetermined timing is after the stapling mechanism 271 has started the stapling operation in which it drives in staples. Therefore, the lamination event can be detected after the laminate has collapsed due to the vibrations of the stapling operation.

[0118] Furthermore, the post-processing device 200 determines that it is time to discard the multiple chips contained in the containment container 251 when stacking events are detected a predetermined number of times consecutively. Conversely, the post-processing device 200 determines that it is not time to discard the multiple chips contained in the containment container 251 when stacking events are not detected a predetermined number of times consecutively. This reduces false detections.

[0119] Furthermore, the post-processing device 200 changes the threshold based on temperature and humidity, which are physical quantities indicating the state of the environment. The threshold is changed according to the state of the environment. The capacitance of static electricity charged on the chips may change depending on the temperature and humidity. Since the threshold is changed according to the temperature and humidity, the timing of disposal of multiple chips contained in the containment container 251 can be detected more accurately.

[0120] Furthermore, the post-processing device 200 changes the threshold after power-on or after opening / closing the outer panel. This makes it easier to detect that chips are still contained in the containment container 251 even if the user has already disposed of the chips contained in the containment container 251. Also, after power-on or opening / closing the outer panel, the user is operating the post-processing device. At the time the user is operating the device, the user can be prompted to dispose of the cut parts contained in the containment container 251.

[0121] <Summary of Embodiments> (Item 1) A punching mechanism that performs a punching operation to cut a portion from a recording medium, A housing section for housing the cut portion cut off from the recording medium, A detection unit detects a stacking event in which the height of a stack of multiple cut portions that fall from the punching mechanism into the housing reaches a predetermined height. A post-processing apparatus comprising: an upper limit determination unit that determines the disposal time of a plurality of cut portions housed in the housing unit based on the number of consecutive stacking events detected by the detection unit at a predetermined timing.

[0122] In this scenario, a stacking event is detected when the height of a stack of multiple cutting parts that fall from the punch mechanism into the storage section reaches a predetermined height. Based on the number of consecutive stacking events detected at predetermined timings, it is determined whether the amount of multiple cutting parts stored in the storage section is at its upper limit. The stack may collapse due to vibration. Before the stack collapses, the stacking event is detected when the excavated parts do not sufficiently fill the storage section's capacity. Since the stacking event is detected at a predetermined timing, it is possible to detect the stacking event at a timing when the probability of the stack collapsing is high. Furthermore, since it is determined whether the amount of multiple cutting parts stored in the storage section is at its upper limit based on the number of consecutive stacking events, stacking events detected when the cutting parts do not sufficiently fill the storage section's capacity can be treated as false detections. Therefore, the upper limit of the cutting parts stored in the storage section can be appropriately detected. As a result, it is possible to provide a post-processing device that can appropriately detect the disposal time while suppressing the increase in the size of the device.

[0123] (Item 2) The post-processing apparatus according to Item 1, wherein the detection unit detects the stacking event at a predetermined timing even if the punching operation is not performed.

[0124] Following this approach, it is possible to detect the lamination event after the occurrence of a laminate collapse event caused by vibrations from actions other than punching.

[0125] (Item 3) The post-processing apparatus according to item 1 or 2, wherein the predetermined timing is after the punching operation has started.

[0126] Following this approach, it is possible to detect the lamination event after the occurrence of a laminate collapse event due to vibrations from the punching motion. (Item 4) The post-processing device further comprises a mechanically operated part, The post-processing device according to any one of items 1 to 3, wherein the predetermined timing is after the operating unit has started operating. Following this approach, it is possible to detect the lamination event after the occurrence of a lamination collapse event caused by vibrations that occur when mechanical operation is initiated.

[0127] (Item 5) The post-processing apparatus according to item 4, wherein the operating unit is a transport unit for transporting the recording medium.

[0128] Following this approach, it is possible to detect the stacking event after it has occurred, following the occurrence of stack collapse due to vibrations that occur when the recording medium is transported.

[0129] (Item 6) A mounting plate on which the recording medium is placed, The system includes an alignment unit that aligns the position of the recording medium placed on the mounting plate, The operating unit is the matching unit, as described in item 4 or 5, in the post-processing apparatus.

[0130] Following this approach, it is possible to detect the stacking event after it has occurred, following the occurrence of a stack collapse event caused by vibrations that occur when the recording media are aligned.

[0131] (Item 7) Further comprising a stapling section for driving staples into paper, The post-processing apparatus according to any one of items 4 to 6, wherein the operating unit is the stapling unit.

[0132] Following this approach, it is possible to detect the lamination event after the occurrence of a laminate collapse event due to vibrations during stapling.

[0133] (Clause 8) The post-processing apparatus according to any one of Clauses 1 to 7, wherein the discard timing determination unit determines that it is time to discard the plurality of cut portions housed in the housing unit when the stacking event is detected a predetermined number of times consecutively, and determines that it is not time to discard the plurality of cut portions housed in the housing unit when the stacking event is not detected a predetermined number of times consecutively.

[0134] In this scenario, if the stacking event is detected a predetermined number of times consecutively, the amount of multiple cut parts to be housed in the housing is determined to be the upper limit, and if the stacking event is not detected a predetermined number of times consecutively, the amount of multiple cut parts to be housed in the housing is determined to be not the upper limit, thereby reducing false detections.

[0135] (Item 9) An environmental value acquisition unit that acquires physical quantities that indicate the state of the environment, The post-processing apparatus according to item 8, further comprising a first threshold changing unit that changes the predetermined number of times based on the physical quantity.

[0136] In this scenario, the predetermined number of cycles is changed depending on the environmental conditions. Depending on the environmental conditions, the capacitance of the electrostatic charge on the cutting portion may change. Since the predetermined number of cycles is changed according to the environmental conditions, it is possible to more accurately detect whether the amount of multiple cutting portions contained in the storage unit is at the upper limit.

[0137] (Item 10) The post-processing device according to item 8 or 9, further comprising a second threshold changing unit for changing the predetermined number of times after power is turned on or after the exterior panel is opened or closed.

[0138] In this scenario, the predetermined number of operations is changed after power-on or after opening / closing the exterior panel. After power-on or after opening / closing the exterior panel, the user is operating the post-processing device. At this time, the user can be prompted to discard the cut parts stored in the storage compartment.

[0139] (Item 11) A post-processing device as described in any of Items 1 to 10, The apparatus comprises an image forming apparatus, The image forming apparatus comprises an image forming unit that forms an image on the recording medium, The predetermined timing is after the image forming apparatus has started mechanical operation, in this image forming system.

[0140] Following this approach, it is possible to provide an image forming system that can appropriately detect the upper limit of the storage capacity while suppressing the increase in size of the post-processing device.

[0141] (Item 12) A method for determining the disposal timing performed by a post-processing device, The post-processing device includes a punching mechanism that performs a punching operation to cut a portion from the recording medium, A housing section for housing the cut portion cut off from the recording medium, The system includes a detection unit that detects a stacking event in which the height of a stack of multiple cut portions that fall from the punching mechanism into the housing reaches a predetermined height. A detection step of controlling the detection unit to detect the stacking event at a predetermined timing, A method for determining the timing of disposal of a plurality of cut portions housed in the housing, including a disposal timing determination step that determines the timing of disposal of a plurality of cut portions housed in the housing based on the number of consecutive stacking events detected in the detection step.

[0142] Following this approach, it is possible to provide a method for determining the appropriate disposal timing while suppressing the need for larger post-processing equipment.

[0143] (Item 13) A program for determining the timing of disposal, which is executed by a computer that controls the after-processing device, The post-processing device includes a punching mechanism that performs a punching operation to cut a portion from the recording medium, A housing section for housing the cut portion cut off from the recording medium, The system includes a detection unit that detects a stacking event in which the height of a stack of multiple cut portions that fall from the punching mechanism into the housing reaches a predetermined height. A detection step of controlling the detection unit to detect the stacking event at a predetermined timing, A disposal timing determination program includes a disposal timing determination step that determines the disposal timing of a plurality of cut portions housed in the housing based on the number of consecutive stacking events detected in the detection step.

[0144] Following this approach, it is possible to provide a disposal timing determination program that can appropriately detect the disposal timing while suppressing the need for larger post-processing equipment.

[0145] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the present invention is indicated by the claims rather than by the foregoing description, and all modifications within the meaning and scope equivalent to the claims are intended to be included. [Explanation of symbols]

[0146] 1 Image forming system, 100 MFP, 200 Post-processing device, 120 Automatic document transport device, 130 Document reading unit, 140 Image forming unit, 150 Paper feeding unit, 160 Operation panel, 161 Display unit, 163 Operation unit, 200 Post-processing device, 201 Main case, 203 Sub-tray, 205 Main tray, 205A Main tray, 205B Main tray, 207 Stacking tray, 209 Connecting port, 210 Transport mechanism, 211 Registration roller pair, 212 Branching point, 213 Intermediate roller pair, 214 Switcher, 215 Sub-discharge roller pair, 217 Storage roller pair, 219 Paddle, 221 Main discharge roller pair, 221a Upper roller, 221b Lower roller, 230 Control unit, 231 CPU, 232 ROM, 233 RAM, 235 Communication unit, 236 External storage device, 237 CD-ROM, 241 Transport control circuit, 242 Staple control circuit, 243 Punch control circuit, 245 Temperature sensor, 246 Humidity sensor, 250 Punch unit, 251 Container container, 253 Photoelectric sensor, 253A Light emitter, 253B Light receiver, 255 Cam plate, 255A Cam groove, 260 Punch mechanism, 261 Punch top, 263 Opposing plate, 263A Through hole, 265 Punch shaft, 265A Sliding member, 267 Drive motor, 270 Staple unit, 271 Staple mechanism, 272 Loading tray, 273 Locking part, 274 Alignment plate, 274L Alignment plate, 274L Alignment plate, 274R Alignment plate, 275 Manual stapling part, 276 Insertion slot, 277 Paper detection sensor, R1 Transport path, R2 Transport path, R3 Transport path, 41 Reversal path, 51 Transport control unit, 53 Punch control unit, 55 Staple control unit, 57 Environmental value acquisition unit, 59 Timing determination unit, 61 Detection unit, 63 Upper limit determination unit, 65 First threshold change unit, 67 Second threshold change unit, 69 Notification unit.

Claims

1. A punching mechanism that performs a punching operation to cut out a portion from a recording medium, A housing section for housing the cut portion cut off from the recording medium, A detection unit detects a stacking event in which the height of a stack of multiple cut portions that fall from the punching mechanism into the housing reaches a predetermined height. A post-processing apparatus comprising: a disposal timing determination unit that determines the disposal timing of a plurality of cut portions housed in the housing unit based on the number of consecutive stacking events detected by the detection unit at a predetermined timing.

2. The post-processing apparatus according to claim 1, wherein the detection unit detects the stacking event at a predetermined timing even if the punching operation is not performed.

3. The post-processing device according to claim 1, wherein the predetermined timing is after the punching operation has started.

4. It further includes mechanically operating parts, The post-processing device according to claim 1, wherein the predetermined timing is after the operating unit has started operating.

5. The post-processing apparatus according to claim 4, wherein the operating unit is a transport unit for transporting the recording medium.

6. A mounting plate on which the recording medium is placed, The system includes an alignment unit that aligns the position of the recording medium placed on the mounting plate, The post-processing apparatus according to claim 4, wherein the operating unit is the matching unit.

7. It also includes a stapling section for driving staples into the paper, The post-processing apparatus according to claim 4, wherein the operating unit is the stapling unit.

8. The post-processing apparatus according to claim 1, wherein the discard timing determination unit determines that it is time to discard the plurality of cut portions housed in the housing unit when the stacking event is detected a predetermined number of times consecutively, and determines that it is not time to discard the plurality of cut portions housed in the housing unit when the stacking event is not detected a predetermined number of times consecutively.

9. An environmental value acquisition unit that acquires physical quantities indicating the state of the environment, The post-processing apparatus according to claim 8, further comprising a first threshold changing unit that changes the predetermined number of times based on the physical quantity.

10. The post-processing device according to claim 8, further comprising a second threshold changing unit for changing the predetermined number of times after power is turned on or after the exterior panel is opened or closed.

11. A post-processing apparatus according to any one of claims 1 to 10, The apparatus comprises an image forming apparatus, The image forming apparatus comprises an image forming unit that forms an image on the recording medium, The predetermined timing is after the image forming apparatus has started mechanical operation, in this image forming system.

12. A method for determining the disposal timing, which is performed by a post-processing device, The post-processing device includes a punching mechanism that performs a punching operation to cut a portion from the recording medium, A housing section for housing the cut portion cut off from the recording medium, The system includes a detection unit that detects a stacking event in which the height of a stack of multiple cut portions that fall from the punching mechanism into the housing reaches a predetermined height. A detection step of controlling the detection unit to detect the stacking event at a predetermined timing, A method for determining the timing of disposal of a plurality of cut portions housed in the housing, including a disposal timing determination step that determines the timing of disposal of a plurality of cut portions housed in the housing based on the number of consecutive stacking events detected in the detection step.

13. A program for determining the timing of disposal, which is executed by a computer that controls the after-processing device, The post-processing device includes a punching mechanism that performs a punching operation to cut a portion from the recording medium, A housing section for housing the cut portion cut off from the recording medium, The system includes a detection unit that detects a stacking event in which the height of a stack of multiple cut portions that fall from the punching mechanism into the housing reaches a predetermined height. A detection step of controlling the detection unit to detect the stacking event at a predetermined timing, A disposal timing determination program includes a disposal timing determination step that determines the disposal timing of a plurality of cut portions housed in the housing based on the number of consecutive stacking events detected in the detection step.

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