Sheet processing apparatus, image forming apparatus, and image forming system

Abstract

To provide a sheet processing device capable of maintaining the accuracy of detecting a filled state of a discharge tray with media even when characteristics of a sheet-like medium and productivity of sheet processing change.SOLUTION: The sheet processing device comprises: sheet conveyance means for conveying sheet-like media fed to a discharge tray which is a discharge destination from upstream; and full-load determination means for determining whether media loaded on the discharge tray have reached an upper limit state. The full-load determination means switches a determination condition for determining the upper limit state on the basis of the amount of media conveyed to the discharge tray per unit time and medium characteristics including a content of processing applied to the media before the media reach the discharge tray.SELECTED DRAWING: Figure 11

Description

Technical Field

[0001] The present invention relates to a sheet processing apparatus, an image forming apparatus, and an image forming system. Background Art

[0002] There is known a sheet processing apparatus that performs so-called post-processing including an aligning process of stacking sheet-like media (sheets) to form a bundle, a folding process of folding sheets or a sheet bundle, and the like. There are also known an image forming apparatus having a function equivalent to that of the above sheet processing apparatus and a function of forming an image on a sheet, and an image forming system that operates by linking the sheet processing apparatus and the image forming apparatus.

[0003] As one of the functions installed in a sheet processing apparatus, a full load detection function for detecting that the upper limit of the stacking amount has been reached in a discharge tray for stacking discharged sheets or sheet bundles is known.

[0004] As a conventional technique for detecting a full load of sheets, there has been known a full sheet detection means including a light-receiving side sensor, a sheet conveying means, a sheet folding means, a sheet detection means for each conveying path such as a sheet conveying path and a sheet folding path, a side wall exterior presence / absence detection means for detecting presence / absence of a side wall exterior of a proof tray, and a control unit configuration for controlling these means (see Patent Document 1). Summary of the Invention Problem to be Solved by the Invention

[0005] The technique described in Patent Document 1 includes full load detection means constituted by a sensor, sheet conveying means, sheet folding means, sheet detection means in each conveying path such as a sheet conveying path and a sheet folding path, and a control unit configuration that controls these means. However, when the productivity of sheets having characteristics that occur in sheets after being subjected to folding processing decreases, there is a problem that the number of sheets stacked on the discharge tray is greatly reduced.

[0006] The present invention aims to provide a sheet processing device that can maintain accuracy in detecting fullness of the sheet-like medium in the discharge tray, even when the characteristics of the sheet-like medium or the productivity of sheet processing change. [Means for solving the problem]

[0007] To solve the above technical problems, one aspect of the present invention includes a sheet conveying means for conveying a sheet-like medium supplied from upstream to a discharge tray as a discharge destination, and a full load determination means for determining whether the medium loaded on the discharge tray is at its upper limit, wherein the full load determination means operates per unit time Before Discharge tray fart being transported The aforementioned medium Based on the quantity, information indicating whether or not the medium has been folded before reaching the discharge tray, information indicating the type of folding, and media characteristics including the size, thickness, and stiffness of the medium, at least, For determining the aforementioned upper limit state It consists of a combination of a threshold and a detection time that detects the time it takes for that threshold to be exceeded. It is characterized by switching the judgment conditions. [Effects of the Invention]

[0008] According to the present invention, even if the characteristics of the sheet-like medium or the productivity of sheet processing change, the accuracy of detecting fullness of the medium in the discharge tray can be maintained. [Brief explanation of the drawing]

[0009] [Figure 1] A side view showing an embodiment of an image forming apparatus including a sheet processing apparatus according to the present invention. [Figure 2] A side view showing an embodiment of an image forming system including a sheet processing apparatus according to the present invention. [Figure 3] A block diagram showing an example of the control configuration according to the above embodiment. [Figure 4] An internal configuration diagram of a folding unit as an embodiment of the sheet processing apparatus according to the present invention. [Figure 5] An enlarged internal diagram showing one step of the folding and transport operation in the folding processing unit described above. [Figure 6]A diagram illustrating the conventional technology in the above folding unit. [Figure 7] This diagram illustrates the challenges of the conventional technology in the above folding unit. [Figure 8] This diagram illustrates the challenges of the conventional technology in the above folding unit. [Figure 9] This diagram illustrates the challenges of the conventional technology in the above folding unit. [Figure 10] A figure showing an example of an upper limit determination table used in an embodiment of the sheet processing apparatus according to the present invention. [Figure 11] A flowchart illustrating an example of the sheet processing operation of the folding unit according to this embodiment. [Figure 12] A flowchart illustrating an example of the sheet processing operation of the folding unit according to this embodiment. [Modes for carrying out the invention]

[0010] [Embodiment of an Image Forming Apparatus] First, an embodiment of the image forming apparatus according to the present invention will be described. Figure 1 is an external view of the printer 10 as an image forming apparatus. The printer 10 according to this embodiment comprises a printer unit 100 as an image forming unit and a folding unit 200 that functions as a sheet processing unit. The folding unit 200 is a unit that works in conjunction with the printer unit 100. In Figure 1, an internal discharge type printer unit 100 is shown as an example. The printer unit 100 has a function that allows the folding unit 200 to be selected as the destination for the discharge of a sheet-like medium (sheet P) on which an image has been formed.

[0011] The folding unit 200, as an embodiment of the sheet processing apparatus according to the present invention, has the function of performing various folding operations. In the following embodiment, the function of stacking multiple sheets P to form a sheet bundle Q and performing folding operations on the sheet bundle Q is exemplified. In the following description, when the folding unit 200 forms a sheet bundle Q and performs folding operations, an example is given in which the folding unit 200 has a circulating transport mechanism that circulates and transports the sheets P to stack them. However, the sheet processing apparatus according to the present invention is not limited to having a circulating transport function like the folding unit 200, but may have the function of discharging the sheets P and the sheet bundle Q to a discharge tray 24, which will be described later as a discharge destination.

[0012] [Embodiment of an Image Forming System] Figure 2 shows a schematic configuration of a printer system 1 as an embodiment of the image forming system according to the present invention. The printer system 1 according to this embodiment is configured by connecting a printer 100a and a folding processing device 200a as a sheet processing device. The printer system 1 operates so that a sheet P on which an image has been formed by the printer 100a is transported to the folding processing device 200a, and a predetermined overlapping folding process is performed in the folding processing device 200a.

[0013] [Functional configuration of the control block] Next, an embodiment of the printer unit 100 and the control block that controls the operation of the folding processing unit 200 as a sheet processing device according to this embodiment will be described with reference to Figure 3. As shown in Figure 3, the printer unit 100 includes a printer control unit 110 as a control block. The printer control unit 110 includes a CPU (Central Processing Unit) 111, a ROM (Read Only Memory) 112, a RAM (Random Access Memory) 113, and a serial I / F 114.

[0014] An image creating section 120, an image reading section 130, and an operation display section 140 are connected to the printer control section 110. The image creating section 120, the image reading section 130, and the operation display section 140 each include a configuration for exerting their respective functions. Each configuration provided in the image creating section 120, the image reading section 130, and the operation display section 140 operates based on a control signal from the printer control section 110.

[0015] The image creating section 120 is configured to perform image forming processing based on image data on a sheet P as a sheet-shaped recording medium. The image reading section 130 is configured to read an image formed on the sheet P and acquire image data. The operation display section 140 has a function serving both as an input section for inputting operating conditions for the image creating section 120 and the image reading section 130, and as a display section for displaying operation results and the like.

[0016] A control program for controlling the image creating section 120, the image reading section 130, and the operation display section 140 is stored in a ROM 112. The CPU 111 reads out the control program stored in the ROM 112 and deploys it in a RAM 113. Then, the CPU 111 causes data necessary for control to be stored in the RAM 113, and executes the control defined by the control program while using the RAM 113 as a work area.

[0017] Further, as shown in FIG. 3, the folding processing unit 200 includes a sheet processing control section 210 as a control block. The sheet processing control section 210 includes a CPU 211, a ROM 212, a RAM 213, and a serial I / F 214.

[0018] The sheet processing control unit 210 is connected to various loads 220, various sensors 240, and an operation display unit 250. The various loads 220 include rollers and roller pairs, which will be described later. The rollers and roller pairs corresponding to the various loads 220 constitute a transport roller pair and a folding roller pair, respectively. The various loads 220 are operated by drive motors that rotate each roller and each roller pair. The drive motors that make up the various loads 220 are operated by a driver 230 that receives instructions from the sheet processing control unit 210. The various loads 220 are configured to perform operations including transport control of the sheet P as a recording medium and folding processing of the sheet P.

[0019] The various sensors 240 are multiple sheet detection means that detect the position of the sheet P within the transport path, and multiple sensors are arranged within the multiple transport paths described later. The transport amount and position of the sheet P and sheet bundle Q, which are the objects to be processed, are determined by a predetermined control program executed by the sheet processing control unit 210 based on detection signals output by the various sensors 240 to the sheet processing control unit 210. The position of the sheet P is calculated by the sheet processing control unit 210 based on the amount of transport (transport distance) of the sheet P since the leading edge of the sheet P was detected by the sheet detection means, and the operating amount of the various loads 220. These transport amounts and operating amounts are also information related to productivity, which will be described later.

[0020] Furthermore, the various sensors 240 include a distance measuring sensor 241, which is provided near the discharge port of the discharge tray 24 as described later. The distance measuring sensor 241 detects the reflected light that is reflected from the uppermost surface of the sheets P and sheet bundles Q loaded on the discharge tray 24, when the light emitted from the light-emitting part towards the discharge direction to the discharge tray 24 is detected from near the discharge port of the discharge tray 24, and outputs a voltage according to the received intensity of the reflected light.

[0021] The output voltage from the distance sensor 241 is used in a control program executed in the sheet processing control unit 210 to determine whether a predetermined upper limit state determination condition is met. When it is determined that the upper limit state determination condition is met, it is determined that the discharge tray 24 is full of loaded material (sheets P and sheet bundles Q). The upper limit state determination condition, as will be described later, determines whether the time for which the output voltage exceeded a predetermined threshold has exceeded a certain period of time (predetermined detection time).

[0022] In other words, the control program executed in the sheet processing control unit 210 constitutes the load determination means according to this embodiment.

[0023] The operation display unit 250 has the function of both a display unit for the processing content in the sheet processing control unit 210 and an input unit for receiving setting information to control the operation (behavior) of the folding processing unit 200.

[0024] The control program for the sheet processing control unit 210 to execute predetermined processing functions is stored in the ROM 212. The CPU 211 reads the control program stored in the ROM 212 and loads it into the RAM 213. The CPU 211 then stores the data necessary for control in the RAM 213 and uses the RAM 213 as a work area to execute the control of the folding operation defined by the control program. As described above, by the sheet processing control unit 210 executing the control program stored in the ROM 212, the detection of sheet P and the transport control of sheet P, which will be described later, can be performed.

[0025] Furthermore, as described above, the output voltage value of the distance sensor 241 is used to determine whether or not the upper limit state determination condition is met, and information processing is performed to determine the loading state of the loaded items in the discharge tray 24.

[0026] The printer control unit 110 of the printer unit 100 and the sheet processing control unit 210 of the folding unit 200 are communicated with each other via serial I / F 114 and serial I / F 214. This communication path is used to exchange control commands and information necessary for controlling the transport of the recording medium. Based on the control commands and information about the sheet P sent from the printer unit 100 and the information about the position of the recording medium obtained from various sensors 240, the folding unit 200 switches whether or not to perform transport control and folding of the recording medium, and the type of folding.

[0027] The information regarding sheet P sent from the printer unit 100 (printer control unit 110) to the folding unit 200 (sheet processing control unit 210) includes the following information.

[0028] For example, the information includes specifications such as the type of sheet P, thickness, and size of the sheet P that is passed from the printer unit 100 to the folding unit 200, information indicating the type of folding process (such as folding or overlapping folding), information indicating the number of sheets P that make up one bundle in overlapping folding, and information indicating the folding position when folding is performed. Furthermore, the control commands notified from the printer control unit 110 to the sheet processing control unit 210 include commands indicating whether the sheet P being passed corresponds to the last page (final sheet) of a unit that is processed as a whole, i.e., a command equivalent to a "notification to start overlapping folding".

[0029] [Internal configuration of the sheet processing device] Next, the internal configuration of the folding unit 200 as an embodiment of the sheet processing apparatus according to the present invention will be described. Figures 4 and 5 are schematic diagrams showing the internal configuration of the folding unit 200. The folding unit 200 includes a plurality of sheet conveying means that perform circulating conveyance to form a sheet bundle Q by stacking sheets P, and a plurality of conveying paths that constitute the conveyance space for the sheets P and sheet bundle Q by the sheet conveying means. In addition, a plurality of sheet detection sensors are installed in each conveying path to detect the conveyance position of the sheets P. Each sheet detection sensor is installed at a predetermined position for controlling the conveyance of the sheets P and sheet bundle Q, which will be described later. Each sheet conveying means is composed of a pair of conveying rollers. That is, the sheets P and sheet bundle Q are conveyed in a predetermined direction by the nip of each pair of conveying rollers. Furthermore, folding is performed on the sheets P and sheet bundle Q depending on how they are fed to the nip of each pair of conveying rollers. Therefore, the plurality of sheet conveying means also constitute folding means.

[0030] The conveying paths provided by the folding processing unit 200 can be broadly divided into seven categories. As shown in Figure 4, it includes the first conveying path W1, the second conveying path W2, the third conveying path W3, the fourth conveying path W4, the fifth conveying path W5, the sixth conveying path W6, and the seventh conveying path W7.

[0031] Multiple roller pairs are arranged along each of the first transport path W1, second transport path W2, third transport path W3, fourth transport path W4, fifth transport path W5, sixth transport path W6, and seventh transport path W7. In other words, the roller pairs constituting the zeroth transport means R0, first transport means R1, second transport means R2, third transport means R3, fourth transport means R4, fifth transport means R5, sixth transport means R6, and seventh transport means R7 are arranged at their respective predetermined positions along the transport paths for transporting the sheet P. The rotation start and stop of each of these transport roller pairs as transport means are controlled by a control program executed by the sheet processing control unit 210. This control enables the start and stop of transport of the sheet P.

[0032] Furthermore, the folding unit 200 is equipped with a transport branching means for switching the transport direction of the sheet P. This transport branching means allows the folding unit 200 according to this embodiment to perform multiple transport processes on the sheet P that is brought in from upstream and held within the unit. The transport processes (transport modes) described below are processes that are switched in conjunction with the sheet P loading process.

[0033] The folding unit 200 is equipped with control functions to perform "discharge transport," "circulation transport," and "fold transport." "Discharge transport," "circulation transport," and "fold transport" are transport processes for sheets P and the like that are performed in the folding unit 200, and are all performed by the operation of each transport roller pair and the transport branching means. In other words, the control operations related to "discharge transport," "circulation transport," and "fold transport" are all performed by the sheet processing control unit 210. Furthermore, the execution of each of these controls may be switched based on control commands from the printer control unit 110.

[0034] Discharge transport is a transport process that transports and discharges sheets P brought in from upstream, and sheet bundles Q formed by stacking already brought-in sheets P and new sheets P, downstream in the transport direction. In other words, "discharge transport" means transporting sheets P or sheet bundles Q in the same direction as the transport direction by the first transport means R1. Specifically, discharge transport means transporting from the first transport path W1 to the fourth transport path W4 downstream in the transport direction, or transporting from the first transport path W1 via the second transport path W2 to the fifth transport path W5. To put it another way, when discharge transport is performed, sheets P or sheet bundles Q are transported from the first transport path W1 toward the exit 22 of the folding unit 200 or the discharge tray 24, regardless of whether folding has been performed or not.

[0035] Circular transport is a transport process in which a sheet P or sheet bundle Q is transported by circulating it upstream of the first transport means R1 (first transport path W1) without changing the leading edge of the sheet P as it is transported along the first transport path W1, that is, without changing the leading edge of the transport direction by the first transport means R1. In other words, it means transporting the sheet P or sheet bundle Q from the first transport path W1 to the second transport path W2 downstream in the transport direction. In "circular transport," in order to return the sheet P that has been sent to the second transport path W2 to the upstream of the first transport path W1, the sheet P is transported from the second transport path W2 to the third transport path W3, and then circulated from the third transport path W3 to the first transport path W1. The transport path through which the sheet P is circulated is called the "circular transport path." Circular transport is performed when the number of sheets P constituting the sheet bundle Q has not reached a predetermined number. Furthermore, the circular transport is performed until the number of sheets P constituting the sheet bundle Q reaches the upper limit for the overlapping and folding process, and the control command for the start of overlapping and folding is recognized by the sheet processing control unit 210.

[0036] "Folding and conveying" is a conveying process that sends a sheet P or sheet bundle Q to the nip of the first folding means F1 at a predetermined folding position. In other words, "folding and conveying" corresponds to conveying the sheet P or sheet bundle Q from the first conveying path W1 to the second conveying path W2 downstream in the conveying direction by changing the leading edge of the conveying direction by the first conveying means R1. Therefore, in folding and conveying, the portion of the sheet P or sheet bundle Q that is not the leading edge in the conveying direction when passing through the nip of the first conveying means R1 is used as the leading edge in the conveying direction and the sheet P or sheet bundle Q is sent to the second conveying path W2, so that the changed leading edge in the conveying direction passes through the nip of the first folding means F1 and a fold is formed. In other words, the changed leading edge in the conveying direction (the leading edge in the conveying direction when sent to the second conveying path W2) becomes the fold. When forming a second fold, a portion different from the previous leading edge in the conveying direction is used as the new leading edge in the conveying direction and sent to yet another conveying path. In this embodiment, the second fold is formed by sending to the fifth conveying path W5. As described above, "folding and conveying" refers to conveying a sheet P or a sheet bundle Q in order to form a fold.

[0037] Furthermore, the transport branching means may also switch to transport from the first transport path W1 to the second transport path W2 and the third transport path W3, and then to the fifth transport path W5. This transport control is also included in "folding transport". As described above, the folding processing unit 200 is equipped with multiple transport paths to enable switching between transport that changes the transport direction of the leading edge of the sheet P or sheet bundle Q and transport that does not change the transport direction of the leading edge. The folding processing unit 200 is equipped with multiple transport branching means to perform the switching of these transport paths.

[0038] Multiple transport branching means are composed of combinations such as a first transport means R1, a fourth transport means R4, a first folding means F1, and a fifth transport means R5. For example, as shown in Figure 5, multiple transport branching means are composed of a first transport branching means J1, a second transport branching means J2, and a third transport branching means J3. These multiple transport branching means are included in various loads 220 whose operation is controlled by the sheet processing control unit 210. Therefore, the sheet processing control unit 210 controls the operation of the sheet transport means that transports sheets P and sheet bundles Q by controlling the operation of the multiple transport branching means, and controls the selective switching of multiple transport paths. In addition, a first folding means F1 and a second folding means F2 for performing folding processing on sheets P and sheet bundles Q are also arranged in the middle of the circulating transport path.

[0039] The folding unit 200 discharges the sheets P received from the printer unit 100 to the discharge tray 24 via the downstream outlet 22 (see Figure 4) or the seventh transport means R7. Before discharge, it receives the next sheet P and performs circulating transport, which is a transport process where the previous sheet P and the subsequent sheet P are stacked on top of each other, or folding transport, which is a transport process for performing a predetermined folding process on the sheet P and the sheet bundle Q.

[0040] [Description of Conventional Examples Related to This Embodiment] Here, we will describe a conventional detection process for determining whether the amount of loaded material (sheets P and sheet bundles Q) on the discharge tray 24 of the folding processing unit 200 has reached its upper limit. Figure 6 illustrates an example of distance measurement using a distance measuring sensor 241 used to determine the upper limit state according to the loading state of the loaded material discharged onto the discharge tray 24.

[0041] Figure 6(a) illustrates a state in which the loading state is determined not to be the upper limit state. Figure 6(b) illustrates a state in which the loading state is determined to be the upper limit state. As already explained, the distance measuring sensor 241 is a sensor that outputs a voltage value corresponding to the level of reflected light emitted toward the uppermost surface of the load placed on the discharge tray 24. Therefore, in the state illustrated in Figure 6(a), the reflected light from the uppermost surface of the load placed on the discharge tray 24 is weak, and the voltage value output from the distance measuring sensor 241 is a low value. The determination of the upper limit state is based on whether or not the output voltage of the distance measuring sensor 241 exceeds a predetermined threshold. In other words, in the state illustrated in Figure 6(a), it is not determined to be the upper limit state (full load).

[0042] On the other hand, in the state illustrated in Figure 6(b), the reflected light from the uppermost surface of the load on the discharge tray 24 is strong, and the voltage value output from the distance measuring sensor 241 becomes high. In other words, the output voltage of the distance measuring sensor 241 exceeds the threshold, so the state illustrated in Figure 6(b) is determined to be the upper limit state (full load).

[0043] Furthermore, the determination of the upper limit state is influenced by the discharge speed of the loaded material to the discharge tray 24, that is, the transport speed to the discharge tray 24 (discharge speed of sheet P or sheet bundle Q). For example, as explained above, even if the output voltage of the distance sensor 241 temporarily exceeds the threshold, if the discharge speed per unit time is fast, the upper limit may fluctuate due to the influence of subsequent loaded material.

[0044] Figure 7 shows an example in which the contents of the discharge tray 24 are determined to satisfy the upper limit condition, where (a) is an example where the discharge rate per unit time is fast, and (b) is an example where the discharge rate per unit time is slow.

[0045] As illustrated in Figure 7, especially when the sheets P or sheet bundles Q used as cargo are folded, it is expected that the top layer will fluctuate as the cargo discharged into the discharge tray 24 expands over time. This fluctuation is suppressed by the weight of subsequent cargo being discharged and replacing the top layer, resulting in a downward fluctuation. As illustrated in Figure 7(a), when the discharge rate per unit time is fast (high productivity), that is, when the time interval between consecutive cargo discharges is short, the distance detected by a predetermined number of items in the discharge tray 24 is "L1". On the other hand, as illustrated in Figure 7(b), when the discharge rate per unit time is slow (low productivity), the time interval between consecutive cargo discharges is long, so even if the predetermined number of items in the discharge tray is the same, the detected distance becomes "L2". Here, L2 corresponds to a shorter distance than L1.

[0046] If the threshold for determining whether the load capacity is at its maximum is a value between L1 and L2, then even with the same number of items loaded, there will be cases where it is determined to be fully loaded and cases where it is determined not to be fully loaded. Therefore, when the productivity of the folding unit 200 and the printer unit 100, which is a higher-level device, are high and low, applying the same conditions for determining whether the load is fully loaded may result in a lower accuracy for one of the determination results.

[0047] In other words, by switching the conditions for determining a full load based on the output voltage of the distance sensor 241 according to the productivity of the folding unit 200 and the printer unit 100, the determination of a full load state can be stabilized.

[0048] Figure 7(c) illustrates the relationship between the distance from the distance sensor 241 to the top of the load and the change in the output voltage of the distance sensor 241. As shown in Figure 7(c), the distance L2 to the top of the load is shorter in the case of low productivity (Figure 7(b)) than the distance L1 to the top of the load is shorter in the case of high productivity (Figure 7(a)), even if the load is the same. In other words, the output voltage of the distance sensor 241 is higher even if the load is the same.

[0049] As the loads are successively placed onto the discharge tray 24, the output voltage of the distance sensor 241 changes over time, as illustrated in Figure 9. In Figure 8, loads are placed on the discharge tray 24 along the time axis (horizontal axis), so the output voltage of the distance sensor 241 fluctuates accordingly. However, even if the output voltage exceeds the threshold, the distance between the distance sensor 241 and the top of the tray temporarily increases (the top of the tray sinks) due to the loading of new loads, so the output voltage may also fall below the threshold.

[0050] In particular, when the cargo includes items that have been folded, the weight of the newly discharged cargo placed on top causes the top layer to temporarily sink. As illustrated in Figure 9, the output voltage fluctuates over time, temporarily decreasing and then increasing.

[0051] Therefore, each time new material is discharged into the discharge tray 24, the output voltage fluctuates so that it temporarily decreases. Thus, it is necessary to set a certain detection time to determine whether or not the upper limit condition is met (whether or not the threshold is exceeded).

[0052] Furthermore, as shown in Figure 10, considering the relationship between the amount of cargo discharged per unit time (discharge interval) and the fluctuation of the output voltage of the distance sensor 241, even if a predetermined detection time is set, the upper limit state can be accurately determined if the period of the output voltage fluctuation matches the detection time. However, as already explained, the speed (discharge interval) of the load discharged to the discharge tray 24 is affected by the productivity of the higher-level equipment, and the greatest variation in the load is due to whether or not the load is prone to bulging (whether or not folding is performed, and what type of folding is performed).

[0053] As explained above, in the conventional example, since the detection time is fixed, if the discharge interval to the discharge tray 24 becomes longer than the predetermined detection time, even if the voltage of the distance measuring sensor 241 falls below the threshold after the predetermined detection time has elapsed, this cannot be detected. As a result, the system will be determined to be full even though it is not actually full.

[0054] In other words, it is necessary to set an optimal detection time for the state in which the output voltage of the distance measuring sensor 241 fluctuates, depending on information related to whether or not folding is performed on the sheet P or sheet bundle Q discharged into the discharge tray 24, the type of folding, and the specifications of the sheet P such as size, thickness, and stiffness. Furthermore, the optimal value for setting the time at which it is determined that the output voltage has exceeded the threshold also changes depending on the discharge rate (productivity) per unit time to the discharge tray 24.

[0055] Therefore, as illustrated in Figure 10, the folding processing unit 200 according to this embodiment is equipped with a function that optimizes the determination conditions for the upper limit state in the discharge tray 24 using a distance measuring sensor 241, according to productivity and the characteristics (media characteristics) of the loaded material.

[0056] Figure 10 shows an example of an upper limit state determination condition table that holds the optimal upper limit state determination conditions corresponding to combinations of system information, specification information, and mode information. The upper limit state determination condition table is stored, for example, in ROM 212.

[0057] As shown in Figure 10, the upper limit state determination condition table stores information on the relevant device, sheet size, and mode, along with the corresponding threshold values ​​and predetermined detection times included in the upper limit state determination conditions. By executing the sheet processing flow using this upper limit state determination condition table, the determination of the upper limit state can be optimized while considering the productivity of the printer unit 100 and the folding processing unit 200, as well as the media characteristics of the loaded material.

[0058] [Sheet Processing Flow] Next, the sheet processing flow performed in the folding unit 200 will be explained with reference to the flowchart. Figure 11 shows the processing flow from when the folding unit 200 starts operation until it completes a predetermined job.

[0059] The folding unit 200 remains in "stopped mode" until sheet processing begins (S1101). Sheet processing then begins (S1102). After sheet processing begins, system information regarding the productivity of the printer unit 100 and the folding unit 200 as upstream devices is acquired (S1103). The system information includes the number of image forming processes per unit time and the number of sheets P discharged to the folding unit 200 per unit time.

[0060] Next, the operating mode of the folding unit 200 is switched from the stopped mode to the job-in-progress mode (S1104). As a result, the printer unit 100 starts the image formation process, and the folding unit 200 performs the specified folding process and starts the discharge process to the discharge tray 24. From there, the job-in-progress mode continues until the operating mode is switched back to the stopped mode, during which the printer unit 100 performs the image formation process and the folding unit 200 performs the folding process based on the job content, and the sheet P and sheet bundle Q are transported to the discharge tray 24.

[0061] Next, information regarding the specifications of the sheet P being transported from upstream (specification information) is acquired (S1105). As mentioned above, the specification information includes information that affects the variation in the loading state in the discharge tray 24 when the sheet P is loaded, such as the size, thickness, and stiffness of the sheet P.

[0062] Next, mode information is acquired (S1106) including whether or not folding processing has been performed on the sheet P being transported from upstream, and the details of the folding processing. The mode information relates to the size, thickness, and stiffness of the sheet P, and when the sheet P is folded, the degree to which it expands when loaded onto the discharge tray 24 changes. Therefore, the mode information also includes information that affects the variation in the loading state on the discharge tray 24.

[0063] Next, based on system information, specification information, and mode information, the system switches to the optimal value for determining the upper limit state, which consists of a threshold value and a predetermined detection time for determining the output voltage of the distance measuring sensor 241 (S1107).

[0064] The criteria for determining the upper limit state are selected and switched by selecting from the information stored in the upper limit state determination criteria table (see Figure 10), which has already been explained.

[0065] In S1107, the conditions for determining the upper limit state are switched, and then the job completion is determined (S1201). If the job has not completed (S1201: No), the output voltage of the distance sensor 241 is then acquired (S1202). This output voltage acquisition process is performed continuously at predetermined timings. For example, it may be acquired in conjunction with the timing when new items are discharged into the discharge tray 24 and placed on top.

[0066] Next, it is determined whether the output voltage of the distance sensor 241 exceeds the threshold for determining the upper limit state condition (S1203). If the output voltage does not exceed the threshold (S1203: No), the time elapsed since the threshold was exceeded is reset (initialized) (S1208), and the process returns to the sensor output voltage acquisition process (S1202).

[0067] Furthermore, if the output voltage of the distance measuring sensor 241 exceeds a threshold for determining the upper limit state condition (S1203: Yes), the elapsed time since the threshold was exceeded is added (S1204). Then, it is determined whether the elapsed time since the threshold was exceeded exceeds a predetermined detection time (S1205). If the elapsed time since the threshold was exceeded does not exceed the predetermined detection time (S1205: No), the process returns to the sensor output voltage acquisition process (S1203).

[0068] As described above, the process returns to the sensor output voltage acquisition process (S1202), and while S1203, S1204, and S1205 are repeated, the folding unit 200 continues to perform folding on the sheet P and the sheet bundle Q and discharge them to the discharge tray 24.

[0069] When the output voltage continues to exceed a threshold and the time elapsed since the threshold was exceeded exceeds a predetermined detection time (S1205: Yes), the discharge tray 24 is full, so the operating mode is switched from job mode to stop mode (S1206). As a result, the discharge of items to the discharge tray 24 is temporarily stopped. At this time, a notification operation may be performed, such as outputting information to the operation display unit 250, such as "The tray is full, please remove the items," prompting the user to remove the items from the discharge tray 24.

[0070] As long as the discharge tray 24 remains full of cargo (S1207: No), the process returns to S1206 and the loop continues. When the discharge tray 24 is no longer full of cargo (S1207: Yes), a determination process is performed to determine whether all jobs have finished (S1201). If the jobs have not finished (S1201: No), the process from S1202 above is performed. If the jobs have finished (S1201: Yes), the sheet processing is terminated (S1208), and the operation mode is set to stopped mode (S1101).

[0071] As described above, according to the sheet processing control in the sheet processing control unit 210 of this embodiment, the set value for the time to detect the height of the loaded material can be switched to an appropriate detection time depending on the system's productivity, whether or not folding is performed, and whether or not the document is folded.

[0072] [Aspects of the present invention] The contents of this invention are, for example, as follows: <1> A sheet conveying means for conveying a sheet-like medium supplied from upstream to an discharge tray which serves as the discharge destination, A load determination means for determining whether the medium loaded on the discharge tray is in an upper limit state, It has, The aforementioned load determination means is The amount of the medium transported to the discharge tray per unit time, The media characteristics, including the processing performed on the medium before it reaches the discharge tray, Based on, Switch the determination conditions for determining the aforementioned upper limit state. This is a sheet processing device characterized by the following features. <2> The aforementioned load determination means is The system includes a distance detection sensor that detects distance by emitting light from a light-emitting part located near the discharge port for discharging the medium into the discharge tray, and detecting the reflected light that is reflected from the uppermost surface of the medium placed on the discharge tray. The determination condition is the distance, <1> This is the sheet processing device described above. <3> The media characteristics are determined by the type of sheeting treatment applied to the media before it is transported to the discharge tray, The above includes specification information indicating the specifications of the medium. <1> or <2> This is the sheet processing device described above. <4> The specification information of the aforementioned medium is information indicating the size, thickness, and stiffness of the medium loaded into the discharge tray. The aforementioned <3> This is the sheet processing device described above. <5> The type of sheet processing refers to information indicating whether or not folding is performed on the medium, and the type of folding. The aforementioned <3> or <4> This is the sheet processing device described above. <6> The aforementioned load determination means is When the distance detected by the distance detection sensor exceeds the determination condition for a certain period of time, the determination condition is switched. <2> This is the sheet processing device described above. <7> The aforementioned sheet transport means is When the load determination means determines that the medium loaded in the discharge tray is full, the transport of the medium to the discharge tray is stopped. The aforementioned <1> from <6> This is the sheet processing device described above. <8> An image forming apparatus comprising an image forming unit for forming an image on a sheet, and a sheet processing unit for performing post-processing on the sheet, The sheet processing unit is the <1> or the above <7> This is an image forming apparatus characterized by being a sheet processing apparatus as described in any of the above. <9> An image forming apparatus comprising an image forming unit that forms an image on a sheet, and the <1> or the above <7> This image forming system is characterized by being configured by connecting a sheet processing device described in any one of the above items with a sheet processing device.

[0073] It should be noted that the present invention is not limited to the embodiments described above, and various modifications are possible without departing from the technical essence, and all technical matters included in the technical concept described in the claims are subject to the present invention. The above embodiments are shown as preferred examples, but those skilled in the art can realize various modifications from the disclosed content. Such modifications are also included in the technical scope described in the claims. [Explanation of Symbols]

[0074] 1: Printer 10: Printer control unit 11: CPU 12: ROM 13: RAM 14: Serial I / F 20: Image Creation Department 21:Entrance 22:Exit 23: Branching claw 24: Output tray 30: Image reading unit 40: Operation display section 50: Post-processing control unit 51: CPU 52 :ROM 53: RAM 54: Serial I / F 60: Load 61: Driver 70: Recovery 100: Printer body 200: Sheet folding device F1: First folding method F2: Second folding method J1: First conveying branching means J2: Second transport branching means J3: Third transport branching means P: Sheet P1: Priority seat P2: Rear seat P3: Next sheet PL: Final seat Q: Sheet bundle R0: Zeroth conveying means R1: First conveying means R2: Second conveying means R3: Third conveying means R4: Fourth conveyance means R5: Fifth conveying means R6: Sixth conveyance means SN1: First sheet detection sensor SN2: Second sheet detection sensor SN3: Third sheet P detection sensor SN4: Fourth sheet detection sensor SN5: Fifth sheet detection sensor SN6: Sixth sheet P detection sensor SN7: Seventh sheet detection sensor W1: First transport path W2: Second transport path W3: Third conveyance path W4: Fourth transport path W5: Fifth transport route W6: 6th conveyance path W7: Seventh transport route [Prior art documents] [Patent Documents]

[0075] [Patent Document 1] Japanese Patent Publication No. 2010-105785

Claims

1. A sheet conveying means for conveying a sheet-like medium supplied from upstream to an discharge tray which serves as the discharge destination, The system includes a load determination means for determining whether the medium loaded on the discharge tray is in an upper limit state, The aforementioned load determination means is The amount of the medium transported to the discharge tray per unit time, Based on media characteristics including information indicating whether or not the media has been folded before reaching the aforementioned discharge tray, information indicating the type of folding, and information indicating the size, thickness, and stiffness of the media, At a minimum, the determination condition consists of a combination of a threshold for determining the upper limit state and a detection time for detecting the time exceeding the threshold, A sheet processing apparatus characterized by the following:

2. The aforementioned load determination means is The system includes a distance detection sensor that detects distance by emitting light from a light-emitting part located near the discharge port for discharging the medium into the discharge tray, and detecting the reflected light that is reflected from the uppermost surface of the medium placed on the discharge tray. The sheet processing apparatus according to claim 1, wherein the threshold for determining the upper limit state is the distance threshold.

3. The aforementioned load determination means is The sheet processing apparatus according to claim 2, wherein the operating mode is switched when the distance detected by the distance detection sensor exceeds a determination condition for a certain period of time.

4. The aforementioned sheet transport means is The sheet processing apparatus according to claim 1, wherein when the load determination means determines that the medium loaded in the discharge tray is full, the transport of the medium to the discharge tray is stopped.

5. An image forming apparatus comprising an image forming unit that forms an image on a sheet, and a sheet processing unit that performs post-processing on the sheet, The image forming apparatus is characterized in that the sheet processing unit is the sheet processing unit described in claim 1.

6. An image forming system characterized by being configured by connecting an image forming apparatus having an image forming unit for forming an image on a sheet and the sheet processing apparatus described in claim 1.

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