JP2020059575A - Sheet post-processing device - Google Patents

Abstract

To provide a sheet post-processing device capable of highly accurately estimating a loading amount on a discharge tray even if a power supply state changes while suppressing the number of sensors.SOLUTION: The sheet post-processing device includes: a movable first discharge tray having a weight sensor; and a fixed second discharge tray located below the first discharge tray and having no weight sensor. The first discharge tray is provided with a member for changing a weight detected by the weight sensor when it comes into contact with a bundle of sheets stacked on the second discharge tray. The first discharge tray is lowered to a predetermined position, and the weight detected at the predetermined position is changed with respect to the weight detected before, it is determined that the second discharge tray is full.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a sheet post-processing apparatus for image-formed sheets.

  2. Description of the Related Art Conventionally, there is a sheet post-processing apparatus that is connected inline to an image forming apparatus, aligns an image-formed sheet with a target, and performs sheet processing (also referred to as post-processing) such as staple binding. The sheet post-processing apparatus of this type includes a first sheet stacking unit (hereinafter referred to as a processing tray) for stacking sheets to be subjected to post-processing conveyed from the image forming apparatus, and a bundle of post-processed sheets. Some have a second sheet stacking unit (hereinafter referred to as a stack tray) that receives and stacks each sheet. In such a sheet post-processing apparatus, placing more sheets than the storage limit number on the stack tray causes a failure of the sheet post-processing apparatus. Therefore, when the discharge of a certain number of sheets from the image forming apparatus is detected, the process of limiting the stacking on the stack tray is performed. As described above, in the stacking restriction process, it is general to judge the stacking excess by counting the number of sheets discharged by the image forming apparatus. Alternatively, a sensor may be used to determine the load amount. Patent Document 1 uses a weight sensor capable of detecting a change in weight of a discharge tray and a sheet passage sensor detecting a passage of a sheet discharged to the discharge tray to detect abnormal discharge of a sheet, particularly a selected type. A configuration that can determine that a paper different from the paper has been discharged is described.

JP 2008-265990 JP

  However, when the stacking amount of the processing tray is specified based on the sheet amount discharged from the image forming apparatus, after the power is turned off or the power saving state (sleep state) is entered, the normal operation mode is set. When returning, the estimated sheet amount may be lost and the full-load estimation may be inaccurate. Further, if all or part of the sheet bundle on the tray is removed during that time, even if the estimated sheet amount is held, the estimated value becomes inaccurate. On the other hand, if the weight sensor is used, if there are a plurality of trays, it is necessary to provide sensors for all of them, which leads to an increase in cost.

  The present invention has been made in view of the above-mentioned conventional example, and it is an object of the present invention to estimate the stacking amount on the discharge tray with high accuracy while suppressing the number of sensors and even when the power state changes.

In order to achieve the above object, the present invention has the following configurations. That is, according to one aspect of the present invention, there is provided a sheet post-processing apparatus for performing post-processing of an image-formed sheet,
A movable first discharge tray having a weight sensor for stacking post-processed sheets;
A fixed second discharge tray below the first tray for stacking post-processed sheets and having no weight sensor;
And a controller that detects the weight detected by the weight sensor and converts it into a sheet amount.
A member for changing the weight detected by the weight sensor when the first discharge tray moves together with the first discharge tray and comes into contact with the sheet bundle stacked on the second discharge tray. Prepare,
The control means lowers the first tray to a predetermined position, and when the weight detected by the weight sensor at the predetermined position is different from the weight detected before reaching the predetermined position. There is provided a sheet post-processing apparatus characterized by determining that the second discharge tray is full.

  According to the present invention, it is possible to estimate the stacking amount on the discharge tray with high accuracy while suppressing the number of sensors and even when the power state changes.

FIG. 3 is an explanatory diagram showing a configuration of an image forming apparatus including a sheet processing apparatus. Explanatory drawing which shows the structure of a sheet processing apparatus. The block diagram of a control structure. Explanatory diagram showing the configuration of the saddle paper ejection unit of the sheet processing apparatus Explanatory drawing showing the configuration for detecting the loading amount The flowchart of a process. The flowchart of a process.

[First embodiment]
Hereinafter, embodiments of the present invention will be described with reference to the drawings. The same reference numerals denote the same or corresponding parts throughout the drawings. Further, in the following description, the up, down, left, and right directions of the drawings will be used as the up, down, left, and right directions of the device or each component described below.

  The present invention will be described with an example of a sheet post-processing apparatus (including an image forming system) that performs post-processing of a sheet on which an image has been formed, which is attached to an image forming apparatus such as an electrophotographic system or an electrostatic recording system To do. The sheet post-processing apparatus of the present invention can employ an inkjet method, a thermal transfer method, various printing methods, etc., instead of the electrophotographic image forming apparatus. For example, not only the printer but also various kinds of devices such as various printing machines, copiers, fax machines, multi-function machines, and conveying devices without a recording unit can be adopted according to various uses. Further, in the present embodiment, a sheet-shaped sheet is assumed as the “sheet”, but a cloth, a plastic film or the like may be used.

  FIG. 1 shows the configuration of an image forming apparatus 100 including a sheet processing apparatus (post-processing apparatus) 119 having a stapler for binding sheet materials. In this embodiment, the sheet processing apparatus 119 installed on the downstream side of the image forming apparatus 100 will be described.

<Image forming apparatus 100>
The image forming apparatus 100 will be described by taking as an example an image forming apparatus that transfers a toner image formed on a photosensitive drum to a recording material (sheet material) to form a monochrome image. However, as the image forming apparatus, a full color image forming apparatus that transfers the toner image of each separated color formed on one or more photoconductor drums to the recording material may be adopted.

  As shown in FIG. 1, the image forming apparatus 100 is a copying machine that forms an image by an electrophotographic method. In the copying machine, a sheet processing apparatus (post-processing apparatus) 119 called a finisher is connected to the downstream side of the apparatus main body 101. The image forming apparatus 100 is controlled by the control unit 201.

  An automatic document feeder (ADF) 102 that supplies the document D to the reading unit of the image forming apparatus 100 is mounted on the top of the apparatus main body 101. The document D is placed on the document placing unit 103 by the user, and is sequentially separated one by one by the feeding unit 104 and is supplied to the registration roller pair 105. Subsequently, the document D is temporarily stopped by the pair of registration rollers 105 to form a loop to correct the skew. Thereafter, the document D passes through the introduction path 106 and the reading position 107, so that the image formed on the surface of the document is read. The document D that has passed the reading position 107 passes through the discharge path 108 and is discharged onto the discharge tray 109.

  When reading both the front and back sides of the original, first, the image of one side of the original is read by passing the original D through the reading position 107 as described above. Thereafter, the document D passes through the discharge path 108 and is stopped while being nipped by the pair of reversing rollers 110. Then, the reversing roller pair 110 carries the switch back, and the reversing roller pair 110 feeds the reversing roller pair 105 again with the front and back reversed.

  Then, in the document D, the skew feeding is corrected by the pair of registration rollers 105, the image on the opposite side is read at the reading position 107, similarly to the case of reading the image on one side. The document D is then discharged to the discharge tray 109 through the discharge path 108.

  On the other hand, the document D passing through the reading position 107 is irradiated with light from the illumination system 111, and the reflected light reflected from the document D is relayed by the plurality of mirrors 112 and guided to the lens 113. The lens 113 projects an image of the document D onto a light receiving element 121 such as a CCD, and the light receiving element 121 reads a line image traversing the document D and converts it into image data.

  The apparatus body 101 uses the photoconductor drum 114 to perform electrophotographic image formation. A charging device, an exposing device, a developing device, a cleaning device and the like necessary for surrounding the rotating photosensitive drum 114 are arranged, but these are not shown.

  An exposure device (not shown) scans the photosensitive drum 114 with laser light modulated based on the image data of the document D, and writes an electrostatic latent image on the surface of the photosensitive drum 114. The electrostatic latent image is developed into a toner image by supplying toner from a developing device (not shown).

  In parallel with this toner image forming operation, sheets (sheet materials) P such as papers or plastic films stacked in the cassette 115 are taken out one by one and stand by at the registration rollers 150. The registration roller 150 sends the sheet P between the photoconductor drum 114 and the transfer unit 116 in synchronization with the toner image on the photoconductor drum 114. Then, the toner image on the photosensitive drum 114 is transferred onto the sheet P by the transfer device 116, and the sheet P on which the toner image is transferred is heated and pressed while passing through the fixing device 117 to form the toner image. It is fixed on the surface. The sheet P that has completed image formation after being fixed is discharged from the apparatus main body 101 by the discharge roller 120 and sent to the sheet processing apparatus 119.

  When images are formed on both sides of the sheet P, the sheet P having an image fixed on one side by the fixing device 117 passes through a double-sided path 118 provided on the downstream side of the fixing device 117 and is switched back and forth in a switchback manner. To be done. Then, the sheet P is again fed between the photoconductor drum 114 and the transfer device 116, the toner image is transferred to the back surface, the toner image is fixed by the fixing device 117, and the sheet processing device is discharged by the discharge roller 120. It is discharged to 119. Under the control of the control unit 900, the sheet processing apparatus 119 performs the sheet post-processing as described with reference to FIG. 2 and discharges the sheet or the sheet bundle to the tray 18a or the tray 18b.

<Sheet processing device 119>
FIG. 2 shows the configuration of the sheet processing apparatus 119. The sheet P discharged from the apparatus main body 101 is guided to a shift unit (not shown). The shift unit may be a part of the sort processing apparatus 119, but here, it is assumed that the shift unit is an optional unit that can be arranged between the main body 101 and the sheet processing apparatus 119. In the shift unit, the sheet P is conveyed by the conveying roller in the shift unit. The shift unit can move in the sub-scanning direction during conveyance of the sheet P. When the sheet reaches a specific position, the conveyance rollers arranged before and after the shift unit are separated to prevent interference with the sheet P. The sheet can be moved in the depth direction (referred to as the width direction) of FIG. 2 which is orthogonal to the transport direction. The sheet whose position in the width direction is adjusted by the shift unit in this manner is conveyed to the sheet processing apparatus 119. Note that the sheet processing apparatus 119 may include a punch unit for punching (punching) near the rear end of the conveyed sheet P, but it is omitted in FIG.

  The sheet processing apparatus 119 is controlled by the control unit 900, and sequentially receives the sheets P discharged from the apparatus main body 101 or optionally through a shift unit and a punch unit, and sequentially receives a horizontal processing unit 500 and a lower folding device. Various sheet processing is performed by allocating to 400. A flapper 551 is arranged at the confluence of the sort path 552 that guides the sheet P to the processing unit 500 and the bookbinding path 553 that guides the sheet P to the folding device 400. Depending on the direction of the flapper 551, the sheet P received by the entrance roller pair 502 from the apparatus main body 101 is sorted into the sort path 552 or the bookbinding path 553. In the non-sort and sort modes, the control unit 900 rotates the flapper 551 downward to guide the sheet P to the sort path 552. In the folding mode, the flapper 551 is rotated upward to guide the sheet P to the bookbinding path 553. The sheet P guided to the sort path 552 reaches the processing section 500. The processing unit (bundling unit) 500 performs a sorting process for aligning a plurality of continuously received sheets P and bundling them into one bundle, a staple process for stapling the vicinity of the rear end of the bundled sheet bundle, and the like.

  In the non-sort mode, the sheet P guided to the sort path 552 by the flapper 551 is directly discharged from the paper discharge port 36 to the stack trays 18a and 18b by the forward rotation of the pair of forward / reverse discharge discharge rollers 560. Simply loaded.

  In the sort mode, the sheet P guided to the sort path 552 by the flapper 551 is pulled back by the reverse rotation after the predetermined amount of normal rotation of the discharge conveyance roller pair 560 and is stacked on the processing tray (intermediate tray) 630. The sheets stacked and bundled on the processing tray 630 are brought into contact with or separated from the pair of sheet discharging and conveying rollers 560 as necessary, and a side surface and a rear end are aligned, and a stapler (post-processing unit) 601 is used. Post-processing such as staple binding processing is performed. After that, the sheet bundle is conveyed by the pair of discharged sheet conveying rollers 560, and is discharged from the sheet discharge port 36 to the stack trays 18a and 18b.

  The stack trays 18a and 18b are movable discharge trays configured to be movable in the vertical direction by the drive motors 225a and 225b and movable in the vertical direction. For example, in the non-sort mode or the sort mode, the control unit 900 detects the stacking amount of the stack trays 18a and 18b in the stacking process. Then, when the stack tray 18a becomes full, the stack tray 18a is moved to a position above the paper discharge port 36 and the discharge destination is switched to the stack tray 18b. . The stack trays 18a and 18b are spin-regulated for sheets or sheet bundles that are not saddle-stitched sheet bundles to be described later.

  Further, in particular, the stack tray 18b is provided with a stacking plate (also referred to as a weight measurement sub-tray) 730 and a pressure sensor 740. The pressure sensor 740 is fixed to the stack tray 18b. The loading plate 730 is not fixed to the pressure sensor 740. Therefore, the pressure sensor 740 can detect the weight of the loading plate 730 as pressure. Further, below the pressure sensor 740, a rod-shaped member 700 is provided in contact with the pressure sensor 740. The lower end of the rod-shaped member 700 is in contact with the end of the sheet pressing member 750, and moves together with the sheet pressing member 750 as the stack tray 18b moves up and down. The sheet pressing member 750 is almost fixed to the stack tray 10b, but is attached so that there is some room for vertical movement with respect to the stack tray 10b. Further, the rod-shaped member 700 is attached to the stack tray so as to have some room for vertical movement, like the pressing member 750. The rod-shaped member 700 is not fixed to the pressure sensor 740. Therefore, when the sheet pressing member 750 is pushed upward, the 0 lower surface of the pressure sensor 400j is pushed from below via the rod member 700.

  On the other hand, in the folding device 400 in which the sheet P has passed through the bookbinding path 553, the continuously received sheets P are overlapped and saddle-stitched / bundle-folded. The sheet bundle that is saddle-stitched and bound by the folding device 400 is discharged and stacked on the saddle tray 832. The saddle tray 832 is a fixed discharge tray that cannot be moved. In the state where the bound sheet bundle stacked on the saddle tray 832 is full, the sheet bundle interferes with the sheet pressing member 750 that is lowered together with the stack tray 18b. Therefore, the sheet pressing member 750 lowers the stack tray 18b until the pressure of the saddle-stitched sheet bundle stacked on the saddle tray 832 is lowered by a certain length from the position of the upper surface of the saddle-stitched sheet bundle when it is fully loaded. Pressure from. By detecting the pressure, it can be determined whether or not the saddle tray 832 is full. Here, the saddle-stitched and bound sheet bundle loaded on the saddle tray 832 may have a bulge at the folding position because it is folded in the middle, but the full load is, for example, pressing the bulge to bring the sheets into close contact. You may judge by the thickness.

<Control configuration>
FIG. 3 is a schematic control block diagram of the sheet processing apparatus 119. As shown in FIG. 3, the control unit 201 of the apparatus main body 101 and the control unit 900 of the sheet processing apparatus 119 exchange data and commands to control each section in the sheet processing apparatus 119.

  The CPU (control unit) 900 of the sheet processing apparatus 119 exchanges data and commands from the control unit 201 of the image forming apparatus 100 via the communication I / F 903. The CPU 900 executes a program stored in the ROM 901, reads data from the ROM 901 based on input information from an operation unit (setting unit) (not shown), and temporarily stores the data in the RAM 902 while controlling each component of the sheet processing apparatus 119. To do. Each configuration includes various motors (tray lifting motors 225a and 225b, a conveyance motor, an offset motor, a sheet bundle discharge motor, a stack tray lifting motor, etc.). Further, various sensors (tray weight sensor (pressure sensor) 740, entrance sensor, sheet ejection sensor, manual staple paper detection sensor, etc.) are included. Furthermore, an actuator (clamp solenoid, center folding solenoid, etc.), pressure sensor 740, stapler 601, processing unit 500, folding unit 400, etc. are included.

  Further, the non-volatile memory 904 stores paper size information, weight sensor 0 correction LS0, weight sensor output value LS1, gram conversion value LS2, and the like. Further, the tray stacking information G1, G2 and the like are stored, but the tray stacking information G1, G2 are fixed threshold values and may be stored in the ROM 901.

  The communication interface (I / F) 903 can communicate with the control unit 201 of the image forming apparatus main body, for example.

  The control unit 201 of the image forming apparatus 100 sends and receives information on the operating mode (copying, sorting mode, stapling mode, saddle mode, standby, etc.) in operation to the control unit 900 of the sheet processing apparatus.

<Calculation of sheet processing time>
At the timing when image formation is started in the apparatus main body 100 shown in FIG. 1 and a sheet is taken out from the paper feed unit 115, the image forming apparatus control unit 201 shown in FIG. A transport preparation request) signal is transmitted. As shown in the figure, the CPU (control unit) 900 extracts the setting of the processing content from the communication data transmitted from the control unit 201 and stores it in the internal RAM. The CPU (control unit) 900 obtains the paper size, determines whether the paper discharge destination is the first tray 18a, the second tray 18b, or the saddle tray 832, and determines whether simple stacking or stapling processing is performed. The processing mode is confirmed, and the sheet processing time (estimated time) of the sheet on which an image is to be formed is calculated based on these settings. Then, the calculated sheet processing time is set in the transmission RAM and returned to the control unit 201 together with the response signal. As a result, the control unit 201 waits for the sheet processing time designated by the control unit 900 and starts the next image formation and sheet discharge.

<Calculation of output tray loading capacity>
The discharge tray 18b shown in FIGS. 4 and 5 is provided with a movable stacking plate 730. When sheets are stacked on the stacking plate 730, pressure is applied to a pressure sensor 740 provided below the stacking plate 730. . Since the resistance of the pressure sensor changes depending on the pressure, the change in resistance value is used to convert into a voltage by the resistance voltage dividing circuit and the value LS1 is sent to the control unit 900. The pressure sensor 740 is in contact with one end of the rod-shaped member 700 extending downward. The other end is in contact with a sheet pressing member 750 that suppresses the center-folded sheet discharged onto the saddle tray 832 from above. The sheet retainer 750 is vertically movable, and when the stack tray 18b is moved downward, both the member 700 and the member 750 move downward (as shown in FIGS. 4 to 5). When there is a stacked sheet on the saddle tray 832, if the sheet is lowered by a certain amount, the pressure from the lower surface of the pressure sensor 400 is applied via the sheet pressing member 750 and the rod-shaped member 700. This pressure acts in the direction in which the pressure detected by the pressure sensor 400 decreases. The output value LS1 of the pressure sensor 400 is also sent to the CPU controller.

  The voltage value LS1 sent to the control unit 900 is converted into the weight LS2 by a predetermined calculation. The weight may be, for example, in grams. This is because the weight of the paper is often expressed in grams and the weight can be easily converted to the number of sheets if the weight and size of the sheet are known.

  In the sheet processing apparatus 119 configured as described above, information such as the operation mode, the size of the sheet P, and the weight is sent from the image forming apparatus 100 to the control unit 900.

<Estimation of loading capacity of output tray>
A specific control flow will be described with reference to FIGS. 3, 4, 6, and 7. First, the procedure for detecting the stacking amount of the stack tray during normal operation will be described with reference to FIG.

  In S110, it is checked whether or not the discharge tray 18b is in operation. If it is in operation, the process returns to S100. If it is determined in S110 that the discharge tray 18b is not in operation, the weight detection process is performed in S120. The operation of the tray means that the tray is moving in the vertical direction. Details of step S120 are shown in FIG.

  First, in step S210, the zero reference value LS0 is read. This value is an output value of the pressure sensor 720 when no sheets are stacked on the stack tray 18b. The zero reference value LS0 is determined once, for example, at the start of use of the image forming apparatus and stored in the “weight sensor 0 correction LS0” of the nonvolatile memory. The stack tray 18b is provided with a sheet presence sensor such as a micro switch, and can detect the presence or absence of a sheet. When there is no seat, the weight at that time is detected and the zero reference value LS0 is stored.

  Next, in step S220, the current signal value of the pressure sensor 740 is read, and the zero reference value LS0 is subtracted from that value to determine the corrected output value LS1. The value is stored in the weight sensor output value LS1 of the nonvolatile memory. Finally, in step S230, the corrected output value LS1 is converted into weight (for example, gram unit). The value is stored in the gram conversion value LS2 (also simply referred to as weight) of the nonvolatile memory.

  When the weight detection in step S120 ends, it is determined in step S130 whether the weight LS2 is equal to or greater than the predetermined weight G1. When it is determined to be G1 or more, it is determined that the number of sheets stacked on the stack tray 18b has reached the upper limit, and in S140, a tray full alarm for the stack tray 18b is transmitted to the control unit 201 of the image forming apparatus. On the other hand, when it is determined in S130 that the weight LS2 is less than the predetermined weight G1, the process returns to S100 and the weight of the stacked sheets on the tray is continuously monitored.

Estimating the tray loading amount when the power is turned on (or returned from sleep) In FIG. 7, it is executed immediately after the image forming apparatus 100 is turned on or immediately after the power saving mode (or sleep mode) is returned to the normal state. 9 shows a flowchart of a procedure for detecting a full state of the saddle tray 832 that is performed. This procedure is also executed by the control unit 900.

  First, in step S310, lowering of the stack tray 18b is started. The stack tray 18b stops when it reaches a predetermined position. When the stack tray starts to descend, weight detection (shown in FIG. 6B) is performed before reaching a predetermined position (S320), and the weight value LS2 is temporarily stored in the RAM 902 as LS2 '(S325). It should be noted that the weight detection may be performed before the lowering of the stack tray 18b is started. Then, the weight value LS2 ′ is compared with a predetermined value G1 (S330), and if it is determined that the weight value is not less than G1, a full alarm for the stack tray 18b is transmitted to the control unit 201 (S340). The predetermined G1 may be the same as the threshold value compared in S130 of FIG. If it is determined in S330 that the weight value is less than the threshold value G1, the process branches to step S343.

  In step S343, it is determined whether the stack tray 18b has reached the predetermined position and stopped. The predetermined position is a position where the sheet pressing member 750 is in contact with the upper surface of the sheet bundle loaded on the saddle tray 832 and pushed upward by a predetermined distance (for example, about several millimeters). That is, this predetermined position is naturally determined from the positional relationship between the sheet pressing member 750 and the saddle tray 832 if the full amount of the saddle tray 832 is determined. Therefore, the control unit 900 may control the motor 225b so as to move the difference between the position before the start of movement and the predetermined position, and stop the motor when it reaches the predetermined position. Therefore, in step S343, it can be determined that the stack tray 18b is at the predetermined position if the movement of the stack tray 18b is stopped.

  If it is determined in step S343 that the stack tray 18b has reached the predetermined position, weight detection is performed again (S346). Then, it is determined whether the difference obtained by subtracting the weight value LS2 measured in step S346 from the weight value LS2 ′ stored in step S325 is less than or equal to a predetermined value G2 (S350). When it is determined that the difference is less than or equal to G2, LS2, which is the loaded weight of the stack tray 18b, is transmitted to the control unit 201 of the image forming apparatus (S370).

  On the other hand, when it is determined that the difference is larger than G2, it is determined that the saddle tray 832 is full of sheet bundles, and an alarm is transmitted to the control unit 201 (S360). This is because when the saddle tray 832 is fully loaded with sheet bundles, the sheet restraining member 750 that has reached a predetermined position is pushed by the fully loaded sheet bundles, and as a result, the pressure sensor 740 is passed through the rod-shaped member 700. Is pushed from below. In this state, a force is applied to the pressure sensor 740 in the opposite direction by the rod-shaped member 750, so that the output value of the sensor 740 is in the negative direction. Therefore, LS2 ′> LS2, and if the difference is larger than a predetermined value G2 including an error and a variation, the saddle tray 832 is determined to be in a full state. Also in step S360, LS2 ′, which is the stacking amount of the stack tray 18b, may be transmitted to the control unit 201 together with the saddle tray full load alarm.

  Although it has been considered that the output value is reduced by further applying pressure from the lower side to the pressure sensor 740, the reverse is also possible. When the output value is increased by further applying pressure from the lower side to the pressure sensor 740, LS2> LS2 ′ should be satisfied when the saddle tray 832 is fully loaded. Therefore, as the value to be compared with the threshold value G2 in step S350, LS2-LS2 'may be used instead of LS2'-LS2.

  Further, the upper end of the rod-shaped member 700 may be configured to push up the stacking plate 730 from below instead of the pressure sensor 740. By doing so, when the saddle tray 832 is fully loaded, the loading plate 730 is pushed up by the rod-shaped member 700 and the pressure applied to the pressure sensor 740 is reduced. Therefore, as shown in FIG. 7, LS2 ′ <LS2 should be satisfied when the saddle tray is fully loaded, and even in this configuration, the loaded state of the saddle tray 832 can be determined by the procedure of FIG. With this configuration, when the saddle tray is fully loaded, the stacking plate 740 can be completely separated from the pressure sensor 740, and the pressure exerted on the pressure sensor 740 by the stacking plate 730 can be zero. Therefore, it is not necessary to determine a minute pressure difference as a weight difference, and a larger value than that in the above embodiment can be used as the threshold G2. Therefore, the accuracy of the determination can be expected to be further improved.

  According to the above embodiment, it is possible to detect the full load of the saddle tray, which is the lowermost stack tray, by using the weight sensor of the lowermost stack tray that moves up and down. Therefore, it is not necessary to use a weight sensor on the saddle tray. Further, even if the power is shut down or the sleep is performed, even if the power state is restored after the sheet bundle is removed from the saddle tray during that time, the full load of the saddle tray can be detected.

[Second Embodiment]
In the present embodiment, the control unit 201 of the image forming apparatus 100 and the control unit 900 of the sheet processing apparatus 119 communicate (for example, communicate) to determine the processing mode and the like, but the sheet processing apparatus 119 makes a self-determination. The control may be changed. Although the sheet processing apparatus 119 is separate from the image forming apparatus 100 in the present embodiment, it may be incorporated in the housing of various image forming apparatuses 100. Further, the control of the sheet processing apparatus 119 is performed by the control apparatus in the sheet processing apparatus 119, but may be performed by the control apparatus of the image forming apparatus 100 or an independent external control apparatus. In the embodiment, the stack trays 18b and 18c have been described as the discharge trays, but the number of trays is not limited. By making the lowermost stack tray have the same structure as the stack tray 18b of the above-described embodiment, it is possible to determine the full load of the saddle tray located further below.

  In the above description, the sheet processing apparatus performing the stapling processing (binding processing) as the post-processing and the image forming apparatus including the sheet processing apparatus have been described as an example, but the present invention is not limited to this. A device that performs a punching process may be adopted.

  The sheet processing apparatus 119 of the present invention is not limited to the configuration of the above embodiment. As long as a plurality of jobs are held and the operation time of one job is used to execute the next job, another embodiment in which a part or all of the configuration is replaced with the alternative configuration can be implemented. is there.

  The functions of the above embodiments can also be realized by the following configurations. That is, it is also achieved by supplying the system or device with the program code for performing the processing of the present embodiment, and causing the computer (or CPU or MPU) of the system or device to execute the program code. In this case, the program code itself read from the storage medium realizes the function of the above-described embodiment, and the storage medium storing the program code also realizes the function of the present embodiment.

  Further, the program code for realizing the functions of the present embodiment may be executed by one computer (CPU, MPU), or may be executed by the cooperation of a plurality of computers. Good. Furthermore, the program code may be executed by a computer, or hardware such as a circuit for realizing the function of the program code may be provided. Alternatively, a part of the program code may be implemented by hardware and the rest may be executed by a computer. Further, the CPU is not limited to one that performs all the processes, and a plurality of CPUs may perform the processes while cooperating appropriately.

100 image forming apparatus, 201 control unit, 119 sheet processing apparatus (post-processing apparatus), 201 image forming apparatus control unit, 700 bar-shaped member, 730 stacking plate, 740 pressure sensor, 750 sheet holding member, 832 saddle tray, 900 control unit

Claims (7)

A sheet post-processing apparatus that performs post-processing of an image-formed sheet,
A movable first discharge tray having a weight sensor for stacking post-processed sheets;
A fixed second discharge tray below the first tray for stacking post-processed sheets and having no weight sensor;
Control means for controlling the movement of the first discharge tray and acquiring the weight detected by the weight sensor,
The first discharge tray is provided with a member that moves together with the first discharge tray and changes the weight detected by the weight sensor when it comes into contact with the sheet bundle stacked on the second discharge tray. Prepare,
The control means lowers the first tray to a predetermined position, and when the weight detected by the weight sensor at the predetermined position is different from the weight detected before reaching the predetermined position. The sheet post-processing apparatus, wherein the second discharge tray is determined to be full. The sheet post-processing device according to claim 1,
The control device determines whether or not the second discharge tray is full when the power of the sheet post-processing device is turned on or when the sheet post-processing device is returned to a normal state. Aftertreatment device. The sheet post-processing apparatus according to claim 1 or 2, wherein
The sheet post-processing device, wherein the control device determines that the first discharge tray is full when the weight detected by the weight sensor exceeds a predetermined value. The sheet post-processing device according to claim 3,
The first discharge tray further includes a sensor for detecting the presence or absence of stacked sheets,
When the control device determines that there is no stacked sheet, the control device stores the weight detected by the weight sensor as a reference weight, and the weight detected by the weight sensor and the reference weight. A sheet post-processing apparatus that determines whether or not the first discharge tray is full based on the difference between The sheet post-processing apparatus according to any one of claims 1 to 4,
One end of the member is in contact with the side of the weight sensor opposite to the side on which the sheets are stacked, and the other end of the member is a stack of sheets stacked on the second discharge tray. The sheet post-processing device, wherein pressure is applied to the weight sensor when abutting. The sheet post-processing apparatus according to any one of claims 1 to 4,
The first discharge tray is provided with a stacking plate on which the sheets are stacked on the weight sensor,
The member lifts the stacking plate when one end of the member contacts the lower surface of the stacking plate and the other end of the member contacts the sheet bundle stacked on the second discharge tray. A sheet post-processing device characterized by: The sheet post-processing apparatus according to any one of claims 1 to 6,
It also has the function of saddle stitching the conveyed sheets,
The saddle-stitched sheet bundle is stacked on the second discharge tray,
A sheet post-processing apparatus, wherein sheets that are not the saddle-stitched sheet bundle are discharged to the first discharge tray.