Sheet processing apparatus and image forming apparatus

Abstract

To provide a sheet processing device capable of improving alignment accuracy of sheet edges.SOLUTION: A sheet processing device that performs post-processing on sheets includes a sheet alignment mechanism that aligns edges of stacked sheets, a sheet gripping and conveying mechanism that grips the stacked sheets and conveys them to the sheet alignment mechanism. The sheet gripping and conveying mechanism reduces the conveying speed of the sheets before the sheets reach the sheet alignment mechanism and then releases sheet-gripping.SELECTED DRAWING: Figure 2

Description

[Technical field]

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

[0002] There are known sheet processing apparatuses that perform an alignment process for aligning sheet-like media (hereinafter referred to as "sheets"), a binding process for binding the aligned sheet stack, a punching process for punching holes in the sheet stack, etc. Also, there are known image forming processing apparatuses that form images on sheets and have a built-in sheet processing apparatus.

[0003] In order to simplify the configuration for aligning sheets, a sheet processing device is also known that is equipped with a sheet gripping and transporting mechanism that grips the edge of the sheet and transports it toward a member against which the edge of the sheet is abutted to align it (see Patent Document 1). Summary of the Invention [Problem to be solved by the invention]

[0004] In the sheet processing device disclosed in Patent Document 1, the gripping is released at the same time as the end of the sheet is abutted against the abutting member for aligning the end of the sheet. As a result, when the sheet is abutted, the inertia of the conveying speed up to that point causes the sheet to bend, and a force to restore the bend acts on the sheet, causing variation in the position where the sheet stops and is stacked. This causes the alignment accuracy of the end of the sheet stack formed by the stacked sheets to be disturbed, and also causes the binding accuracy to be reduced by performing a binding process on a sheet stack with a misaligned alignment.

[0005] That is, according to the conventional technology, there is a problem that the accuracy of sheet alignment decreases when the conveying mechanism for aligning the sheets is simplified.

[0006] SUMMARY OF THE PRESENT EMBODIMENT An object of the present invention is to provide a sheet processing apparatus capable of improving the alignment accuracy of the edge of a sheet. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention provides a sheet processing apparatus for performing post-processing on a sheet, Ta The sheet Transport direction A sheet alignment mechanism for aligning the edge of the sheet; Note Grasp the handle And before Sheet alignment mechanism to the sheet a sheet gripping and conveying mechanism for conveying the sheet; a sheet detection sensor that detects when the end portion of the sheet being aligned by the sheet alignment mechanism approaches the sheet alignment mechanism by a certain distance or less; The sheet gripping and conveying mechanism includes: When the sheet detection sensor detects the edge, the conveying speed to the sheet alignment mechanism is decelerated to convey the sheet, and when the gripping of the sheet conveyed at the decelerated conveying speed is released, the sheet is moved until the edge abuts against the sheet alignment mechanism due to an inertial force acting on the sheet based on an attribute of the sheet. The grip is released. Effect of the Invention

[0008] According to the present invention, the alignment accuracy of the edge of the sheet can be improved. [Brief description of the drawings]

[0009] [Figure 1] 1 is a schematic configuration diagram of a printer as an embodiment of an image forming apparatus according to the present invention. [Diagram 2] 1 is a schematic configuration diagram showing a part of an embodiment of a sheet processing apparatus according to the present invention. [Diagram 3] 1 is a schematic configuration diagram illustrating an embodiment of a sheet processing apparatus according to the present invention. [Figure 4] FIG. 4 is a diagram for explaining the flow of operations of the sheet processing apparatus. [Diagram 5] FIG. 4 is a diagram for explaining the flow of operations of the sheet processing apparatus. [Figure 6] FIG. 2 is a block diagram showing a configuration of a control unit that controls the operation of the sheet processing apparatus. [Figure 7] 5A and 5B are diagrams illustrating an example of sheet gripping and transport control in the sheet processing apparatus. [Figure 8] 11A and 11B are diagrams illustrating another example of sheet gripping and transporting control in the sheet processing apparatus. [Figure 9] 13 is a diagram showing still another example of sheet gripping and transporting control in the sheet processing apparatus. FIG. [Figure 10] 13 is a diagram showing still another example of sheet gripping and transporting control in the sheet processing apparatus. FIG. [Figure 11]6 is a flowchart showing a flow of sheet gripping and transporting control in the sheet processing apparatus. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The present invention relates to a mechanism for reducing disturbance during alignment in a sheet processing apparatus and an image forming apparatus. Specifically, when post-processing a sheet-like medium, the medium is transported onto a processing tray on which the medium is stacked, and the end of the medium is aligned, the mechanism weakens the inertial force of the medium before the end of the medium strikes an abutting member. For example, by providing a mechanism for weakening the inertial force by slowing down the moving speed (i.e., the transport speed of the medium) of the gripping and transporting mechanism that grips and transports the medium before the end of the medium strikes the abutting member, the deflection of the medium when it strikes the abutting member is reduced. As a result, it is possible to suppress the phenomenon in which the loading position of the medium is disturbed due to the force of the medium trying to return to its original deflection, and improve the alignment accuracy of the end of the medium loaded on the processing tray.

[0011] [Embodiment of Image Forming Apparatus] 1 is a schematic front view showing the configuration of an MFP (Multi Function Peripheral) 1 as an embodiment of an image forming apparatus. The MFP 1 includes a sheet supply cassette 211 for stacking and storing sheets P, which are a number of sheet-like media.

[0012] In the following description, since it is necessary to clearly indicate the direction of movement of sheet P, commonly used axes are clearly indicated in FIG. 1. In this specification, the horizontal direction of MFP1 shown in FIG. 1 is defined as the Y direction. Based on FIG. 1, the Y direction corresponds to the width direction of MFP1. Also, the direction parallel to the placement surface of MFP1 and perpendicular to the Y direction is defined as the X direction. Based on FIG. 1, the X direction corresponds to the depth direction of MFP1. And the vertical direction perpendicular to the X and Y directions is defined as the Z direction. Based on FIG. 1, the Z direction corresponds to the height direction of MFP1.

[0013] Sheets P as sheet-like media are separated and fed out one by one from the storage space of a sheet supply cassette 211 by a separation roller 212 and a friction pad 213, and then conveyed. The sheets P fed out from the sheet supply cassette 211 are conveyed to an image forming unit 220 as an image forming section by a pair of sheet supply rollers 214. The MFP1 includes a plurality of sheet supply cassettes 211, and each sheet supply cassette 211 is capable of storing sheets P of different types, thicknesses, etc.

[0014] The image forming unit 220 includes ejection heads each having an ejection port that ejects ink liquid of each of the colors Y (yellow), M (magenta), C (cyan), and B (black) toward the sheet P. The ejection heads are provided separately corresponding to the ink liquid of each color, and ink liquid of the color corresponding to each ejection head is ejected from the nozzles provided in each ejection head.

[0015] The MFP1 also has a cartridge loading section 221 that houses ink cartridges 222 (222B, 222C, 222M, 222Y) that store ink liquid of each color. The ink cartridges 222 (222B, 222C, 222M, 222Y) are connected to a supply pump, and by appropriately driving the supply pump, the ink liquid in the ink cartridges 222 is supplied to the image forming unit 220. Note that the supply pump is omitted from the illustration. Furthermore, the ink cartridges 222 of each color are detachably attached to the cartridge loading section 221.

[0016] The timing of conveying the sheet P is adjusted by a sheet supply roller pair 214, and the sheet P is conveyed by a plurality of sheet conveying roller pairs 215 to a position facing the image forming unit 220. Then, ink liquid as an image forming material is ejected from the image forming unit 220 onto the conveyed sheet P, forming an image. The sheet P on which the image has been formed is conveyed downstream in the conveying direction by a plurality of discharge roller pairs 216.

[0017] A plurality of conveyance path switching units for switching the conveyance direction of the sheet P are provided in the middle of the discharge conveyance path formed by the pair of discharge rollers 216 consisting of a discharge roller and a spur. A first switching claw 2191 as a conveyance path switching unit switches so that the sheet P is conveyed to either a drying path that passes through the drying unit 217 or a normal path that does not pass through the drying unit 217.

[0018] The drying unit 217 is, for example, a pair of drying rollers composed of a heating roller and a roller having good releasability from the ink liquid. An infrared heater or the like can be used as a heating means for the heating roller of the drying unit 217. Note that the installation positions and the number of installations of the drying units 217 are not limited to the positions and the number exemplified in FIG.

[0019] Further, the second switching claw 2192 as a conveying path switching section switches the conveyance of the sheet P that has come out of the sheet conveying roller pair 215 to a reverse conveying path in which an image is also formed on the second surface (rear surface) side as a reverse conveying. A plurality of reverse conveying roller pairs 218 are provided on the reverse conveying path, and the reverse conveying roller pair 218 returns the sheet P to the conveying path formed by the sheet conveying roller pair 215. The reverse conveying roller pair 218 conveys the sheet P with the opposing surface to the image forming unit 220 switched, and an image can also be formed on the second surface (rear surface) of the sheet P.

[0020] The sheet P on which the image is formed may be discharged to a sheet discharge tray 240 or may be conveyed to a post-processing unit 10 as a post-processing device. A third switching claw 2193 as a conveying path switching section is provided at a predetermined position to switch the conveying path to these.

[0021] When post-processing is not performed on the sheet P, the third switching claw 2193 is switched to the direction of the conveyance path toward the sheet discharge tray 240, and the sheet P is discharged to the sheet discharge tray 240. When post-processing is performed on the sheet P, the third switching claw 2193 is switched to the direction of the post-processing conveyance roller pair 2161, and the sheet P is conveyed to the post-processing unit 10.

[0022] Moreover, an image reading unit 30 that reads an original is disposed above the MFP 1. The image reading unit 30 also includes an automatic transport device 31 that transports the original. The image reading unit 30 includes an image reading element such as a CCD, and is provided with a mechanism for reading images and characters formed on a sheet P as image signals. The image signals read by the image reading unit 30 are subjected to digital processing and image processing. Based on the image data after these processes, the operation of the image forming unit 220 is controlled, and an image read from the original can be formed on the sheet P.

[0023] [Embodiment of the sheet processing device] Next, the configuration of the post-processing unit 10 as an embodiment of the sheet processing apparatus according to the present invention will be described with reference to the drawings. When post-processing is performed on the sheet P on which an image is formed by the image forming unit 220, the sheet P passes through the delivery path 11 and the downstream end of the sheet P in the conveying direction is detected by the first sheet detection sensor 250. Based on the detection by the first sheet detection sensor 250, the post-processing conveying roller pair 2161 conveys the sheet P at a predetermined conveying speed to the post-processing unit 10 arranged downstream in the conveying direction.

[0024] The post-processing unit 10 includes a sheet conveying and gripping mechanism. The sheet conveying and gripping mechanism includes a sheet clamp 110 as a sheet conveying and gripping section that grips and conveys an end of the sheet P. Here, the end of the sheet P that is gripped by the sheet clamp 110 corresponds to the leading end of the sheet P when it is conveyed toward the sheet clamp 110, and is the downstream end of the sheet P in the conveying direction.

[0025] The sheet clamp 110 includes a clamp bar 111 and a clamp arm 112 attached to the clamp bar 111, and is configured to hold a sheet P by sandwiching it between the clamp bar 111 and the clamp arm 112.

[0026] A spring 113 is attached to the clamp arm 112 as an example of an elastic member serving as an urging means. The clamp arm 112 is constantly urged by the elastic force of the spring 113 to close the gap formed between the clamp arm 112 and the clamp bar 111. That is, the clamp arm 112 operates to pinch and grip the sheet P between the clamp arm 112 and the clamp bar 111 by the elastic force of the spring 113. That is, the clamp arm 112 is constantly urged downward by the spring 113.

[0027] In addition, the clamp bar 111 is attached to a clamp movement belt 123 that is stretched between a first clamp movement roller 121 and a second clamp movement roller 122. The first clamp movement roller 121 and the second clamp movement roller 122 rotate using, for example, a pulse motor as a drive source.

[0028] 2, when the first clamp moving roller 121 and the second clamp moving roller 122 rotate clockwise, the clamp moving belt 123 also rotates in the same direction (clockwise). Then, in conjunction with the clamp moving belt 123, the sheet clamp 110 moves in a direction from the first clamp moving roller 121 toward the second clamp moving roller 122. At this time, if the sheet P is held between the clamp bar 111 and the clamp arm 112, the sheet P is transported in a direction from the first clamp moving roller 121 toward the second clamp moving roller 122 as the clamp bar 111 moves.

[0029] 2, an opening member 114 is provided below the clamp arm 112 and below the clamp movement belt 123 in the Z direction. The opening member 114 is in contact with the bottom surface of the clamp arm 112 and is a member that moves in the vertical direction by the driving force from the clamp driving source 115. The amount of the gap between the clamp bar 111 and the clamp arm 112 varies according to the movement of the opening member 114 by the driving force supplied from the clamp driving source 115.

[0030] As the clamp driving source 115, for example, a stepping motor or a DC motor can be applied. When the opening member 114 moves upward in FIG. 2 by the clamp driving source 115, the clamp arm 112 also moves upward. This movement increases the gap between the clamp bar 111 and the clamp arm 112. Furthermore, if the clamp driving source 115 is not operated, there is no force to move the opening member 114 upward, so the clamp arm 112 moves downward by the elastic force of the spring 113. This movement reduces the gap between the clamp bar 111 and the clamp arm 112. Therefore, when the sheet clamp 110 grips the end of the sheet P, the clamp driving source 115 is not operated. Furthermore, when the sheet clamp 110 releases the sheet P from the state in which it was gripping the sheet P, the clamp driving source 115 is operated to raise the opening member 114.

[0031] The timing of the operation of gripping the edge of the sheet P by the operation of the clamp drive source 115 is set based on the timing when the first sheet detection sensor 250 detects the edge of the sheet P and the speed at which the post-treatment conveying roller pair 2161 conveys the sheet P. The distance between the first sheet detection sensor 250 and the sheet clamp 110, which is in the initial position (home position) for the sheet clamp 110 to grip the sheet P, is specified in advance. Therefore, the operation timing for gripping the edge of the sheet P can be calculated by the control unit 150, which will be described later, based on the distance therebetween and the conveying speed at which the sheet P is conveyed to the sheet clamp 110.

[0032] [Example of operation of the post-processing unit 10 when performing post-processing] Next, the basic operation of the post-processing unit 10 will be described using a comparative example with the embodiment of the present invention. Fig. 3 is a plan view of the post-processing unit 10. Fig. 4 is a process diagram illustrating the stages of the operation of the post-processing unit 10. Figs. 3 and 4 illustrate a comparative example to clarify the features of the embodiment of the present invention described later.

[0033] 3, the post-processing unit 10 has a sheet clamp 110 as a sheet gripping and conveying mechanism, a sheet abutting section 131 as a sheet alignment mechanism, and a sheet pressing section 132 as a sheet stack holding mechanism. The post-processing unit 10 also has a sheet processing tray 133 as a sheet placement section for stacking sheets P, support members 135 (135a, 135b) for supporting sheets P stacked on the sheet processing tray 133, and arm members 136 (136a, 136b) for moving the support members 135 between predetermined positions.

[0034] As shown in FIG. 4, the sheet processing tray 133 is provided with a transport sensor 138 as a second sheet detection sensor for detecting the end of the sheet P on the downstream side in the transport direction. The transport sensor 138 is an optical sensor and detects the leading edge of the sheet P (the end on the downstream side in the transport direction). The transport sensor 138 may detect the passage of the sheet clamp 110 instead of detecting the end of the sheet P. Either detection means may be used as long as it can detect that the position of the end on the downstream side in the transport direction of the sheet P has passed a predetermined position. The transport sensor 138 may detect the end on the upstream side in the transport direction of the sheet P.

[0035] Fig. 4(a) illustrates a state in which the sheet clamps 110 grip both ends in the width direction of the sheet P. From the state in Fig. 4(a), the first clamp movement roller 121 and the second clamp movement roller 122 rotate (see Fig. 2), and the sheet clamp 110 moves in the rotation direction of the clamp movement belt 123, thereby transporting the sheet P to the sheet processing tray 133. Fig. 4(b) illustrates a state in which the sheet P has been transported to a position where it can be placed on the sheet processing tray 133.

[0036] At this time, the arm members 136 (136a, 136b) rotate from the outer side to the inner side at both ends in the width direction of the sheet P, and the support members 135 (135a, 135b) move to a position where they support the lower surface of the sheet P (see FIG. 3). This makes the sheet P available for stacking on the sheet processing tray 133.

[0037] Then, as shown in Fig. 4(c), when the movement of the sheet clamp 110 causes the end of the sheet P in the conveying direction to reach a position where it contacts the sheet abutment portion 131, the sheet clamp 110 releases the sheet P. As a result, as shown in Fig. 4(d), the sheet P is placed on the sheet processing tray 133. By repeating this, a predetermined number of sheets P can be stacked on the sheet processing tray 133 to form a sheet bundle.

[0038] Whether or not the sheet P has reached the abutment position is determined by monitoring whether the sheet clamp 110 has moved a predetermined distance from a reference position, based on the position where the transport sensor 138 detects the end of the sheet P in the transport direction.

[0039] After the sheet clamp 110 releases the sheets P, the conveyance direction ends of the sheets P are pressed by a sheet pressing unit 132 that maintains the aligned state of the ends of the sheet stack, thereby suppressing bending of the ends of the sheets P and maintaining the aligned state of the sheet stack. Thereafter, the side ends of the sheet stack are stapled by a staple unit 134 that performs a binding process as an example of post-processing.

[0040] When the stapling process of the sheet stack is completed, as illustrated in Fig. 5(a), the arm members 136 (136a, 136b) rotate toward both ends (outsides) in the width direction of the sheets P, and the support members 135 (135a, 135b) move from the support positions for the sheets P to the initial positions. Then, as illustrated in Fig. 5(b), the rear end side of the sheet stack drops down to the sheet stack discharge tray 230 due to gravity.

[0041] Next, by rotating the sheet processing tray 133 downward, the entire sheet stack is placed on the sheet stack discharge tray 230 as shown in FIG. 5(c).

[0042] According to the operation of the sheet clamp 110 based on the comparative example described above, the sheet clamp 110 releases the sheet P in accordance with the timing when the sheet P abuts against the sheet abutment portion 131. In other words, the sheet clamp 110 releases the sheet P after the end of the sheet P in the conveying direction abuts against the sheet abutment portion 131. In this case, the sheet P is deflected in the conveying direction at the same time as the sheet abuts against the sheet abutment portion 131 due to inertia caused by conveying. As a result, a force that returns the deflection is generated in the sheet P. This force causes the sheet P to move in a direction away from the sheet abutment portion 131. In other words, the sheet P collides with the sheet abutment portion 131 and bounds due to inertia when the sheet clamp 110 conveys the sheet P. As a result, the position at which the sheet P is placed on the sheet processing tray 133 varies depending on the sheet P. In other words, with the operation of the comparative example described so far, the alignment accuracy of the edge of the sheet P on the sheet processing tray 133, particularly the alignment accuracy of the edge in the transport direction, decreases, and then, when the binding process is performed, the alignment accuracy of the binding edge of the sheet stack decreases.

[0043] [Embodiment of the control block] The operation control of the sheet clamp 110 that can solve the problems in the comparative example described above will be described. Fig. 6 illustrates the configuration of the control unit 150 as a control unit according to the embodiment of the present invention. The control unit 150 controls the operation of the post-processing unit 10, but Fig. 6 mainly illustrates the control block of the sheet clamp 110.

[0044] The control unit 150 includes a sheet clamp control unit 151, a sheet conveying speed setting unit 152, a release timing adjustment unit 153, and a sheet detection unit 154. Each of these functional blocks is realized by executing a control program in an information processing unit that performs control processing of the post-processing unit 10.

[0045] The sheet clamp control unit 151 controls the operation of the sheet clamp 110. For example, it controls the operation of the clamp drive source 115 so that the sheet clamp 110 grips and releases the end of the sheet P at a predetermined timing. In addition, the sheet clamp control unit 151 controls the rotation speeds of the first clamp movement roller 121 and the second clamp movement roller 122 so that the sheet clamp 110 moves at a set movement speed.

[0046] The sheet conveying speed setting unit 152 sets the moving speed of the sheet clamp 110. For example, the moving speed of the sheet clamp 110 is set based on information indicating the attributes of the sheet P that affect the magnitude of the inertial force acting on the sheet P when the sheet P to be conveyed is moved. "Information indicating the attributes of the sheet P" refers to, for example, the size of the sheet P, the thickness of the sheet P, and the amount of image forming material (ink liquid) attached to the sheet P when an image is formed on the sheet P held and conveyed by the sheet clamp 110. Any combination including one or more of the elements listed above corresponds to "information indicating the attributes of the sheet P that affect the magnitude of the inertial force acting on the sheet P."

[0047] The sheet conveying speed setting unit 152 sets a set value of the moving speed stored in advance as a specified value in a storage area provided in the control unit 150 to the sheet clamp control unit 151, and also uniquely determines the moving speed of a certain type of sheet P based on at least one or a combination of the above-mentioned "information indicating the attributes of the sheet P". Then, the sheet conveying speed setting unit 152 sets the determined moving speed to the sheet clamp control unit 151.

[0048] The release timing adjustment unit 153 calculates the release timing of the sheet clamp 110 or the distance until the sheet clamp 110 moves to a position corresponding to the release timing based on a detection signal from the sheet detection unit 154 and the attributes of the sheet P. For example, based on information indicating an attribute that influences the magnitude of the inertial force acting on the sheet P when the sheet P to be transported is moved and that correlates with the weight of the sheet P, the release timing adjustment unit 153 calculates the release timing or the release position (distance from the home position) at which the sheet clamp 110 releases the sheet P to suppress the inertia of the sheet P. The release timing adjustment unit 153 stores the calculated setting value of the release timing in a storage area provided in the control unit 150. The sheet clamp control unit 151 executes the release operation of the sheet P based on the stored setting value.

[0049] The sheet detection unit 154 notifies the sheet clamp control unit 151 of a detection signal from the first sheet detection sensor 250. The sheet clamp control unit 151 calculates the timing at which the end of the sheet P in the conveying direction reaches the sheet clamp 110 based on the detection signal from the first sheet detection sensor 250. Then, based on the calculated arrival timing, the operation of the clamp drive source 115 is stopped, and the operation of the sheet clamp 110 to grip the sheet P is controlled.

[0050] Furthermore, the sheet detection unit 154 notifies the release timing adjustment unit 153 of a detection signal from the transport sensor 138 serving as a second sheet detection sensor. The release timing adjustment unit 153, which has received the detection signal, calculates the timing of the release operation of the sheet clamp 110 based on the attributes that affect the magnitude of the inertial force acting on the sheet P, the moving speed of the sheet clamp 110, and the timing at which the transport sensor 138 detects the end of the sheet P in the transport direction. Then, the calculated release timing is set in the sheet clamp control unit 151 via a storage area. The sheet clamp control unit 151 controls the release operation of the sheet clamp 110 based on the set release timing.

[0051] The characteristic operation of the post-processing unit 10 according to this embodiment is the same as that of the comparative example shown in FIG. 4 and the like in terms of hardware configuration. Therefore, as described later, the sheet processing tray 133 is provided with a transport sensor 138 as a second sheet detection sensor for detecting the end of the sheet P, which is the downstream end in the transport direction. The transport sensor 138 is an optical sensor that detects the leading end (the downstream end in the transport direction) of the sheet P, and may also detect the upstream end of the sheet P in the transport direction. The transport sensor 138 may be configured to detect the passage of the sheet clamp 110, rather than the end of the sheet P. Whatever the configuration and detection means, it is sufficient as long as it is configured to detect information that is the basis for determining the position at which the sheet clamp 110 releases its grip on the sheet P,

[0052] The conveying sensor 138 is not an essential component and may be omitted. In this case, the timing at which the sheet clamp 110 grips the sheet P and starts conveying it based on the detection signal from the first sheet detection sensor 250 is determined by the distance from the first sheet detection sensor 250 to the initial position (L0) of the sheet clamp 110 and the conveying speed over this distance. The distance from the position at which the sheet clamp 110 grips the sheet P and starts conveying it to the position at which the sheet P should be released can be determined by the attributes of the sheet P and the conveying speed of the sheet clamp 110. The movement of the sheet clamp 110 to the "position to be released" can be controlled by the number of steps of the pulse motor that drives the first clamp moving roller 121 and the second clamp moving roller 122. In this case, the moving distance after the sheet clamp 110 grips the sheet P and starts conveying it is calculated based on the number of steps of the pulse motor, and the release operation is performed when the position of the leading end of the sheet P in the conveying direction reaches the position at which the sheet P gripped by the sheet clamp 110 should be released. During this time, as described later, when the sheet P reaches a position where the conveying speed is to be slowed down, the moving speed of the sheet clamp 110 is slowed down.

[0053] Here, a control operation in which the sheet clamp 110 releases the grip of the sheet P at a predetermined position without using the conveying sensor 138 is exemplified. For example, the time T1 required for the sheet clamp 110 to move the distance from the position where it grips the sheet P to the sheet abutment portion 131 at a conveying speed (V01) described later is calculated. The time T1 is set in a timer possessed by the control portion 150, and when the remaining time on the timer reaches time T2, which is half of the time T1, the conveying speed is decelerated to a decelerated conveying speed (V11). As described above, the deceleration of the sheet P and the release operation of the sheet clamp 110 can also be controlled according to the detection timing of the sheet P by the first sheet detection sensor 250 and the distance of each member of the movement mechanism that moves the sheet clamp 110.

[0054] [First embodiment of sheet clamp transport process] Next, a first embodiment relating to the operation of the sheet clamp 110 will be described with reference to Fig. 7. Fig. 7(a) is a timing chart showing the transition of the conveying speed of the sheet clamp 110 relative to the leading edge position in the conveying direction (movement direction) of the sheet P. Fig. 7(b) shows the correspondence between the layout and the leading edge position in the conveying direction of the sheet P. The same applies to Figs. 8, 9, and 10 below.

[0055] The flow of operational control of the sheet clamp 110 will also be described with reference to the flowchart in Fig. 11. First, when the sheet P is conveyed and the end of the sheet P reaches a position where it can be gripped by the sheet clamp 110, the clamp drive source 115 operates so that the release member 114 is lowered by the bias of the spring 113 (S1101). At this time, the leading edge of the sheet P is assumed to be at position L0 (see Fig. 7(a)).

[0056] Next, the sheet clamp control unit 151 controls the movement of the sheet clamp 110 at the set movement speed (S1102). The conveying speed (V01) here may be determined according to the type of the sheet P, such as the size or thickness, or may be a uniform fixed value. This movement process continues as it is until the conveying sensor 138 detects the end of the sheet P (end in the conveying direction) (S1103: NO).

[0057] When the conveying sensor 138 detects the end of the sheet P in the conveying direction (S1103: YES), the end of the sheet P is at the position L1. When the end of the sheet P exceeds L1, the sheet clamp control unit 151 decelerates the moving speed of the sheet clamp 110, i.e., the conveying speed of the sheet P, and sets it to a conveying speed (V11). The conveying speed (V11) is set to a speed at which bending or bouncing does not occur even if the leading edge of the sheet P collides with the sheet abutment unit 131.

[0058] Thereafter, the sheet clamp control unit 151 conveys the sheet 110 to the distance (L2) to the sheet abutment unit 131 while keeping the sheet clamp 110 at the decelerated conveying speed (V11) (S1104, S1105: NO).

[0059] When the movement distance of the end portion of the sheet P reaches the distance (L2) to the sheet abutment portion 131 (S1105: YES), the sheet clamp control portion 151 releases the grip of the sheet P.

[0060] When the end of the sheet P in the conveying direction reaches the sheet abutment portion 131 and thereafter the sheet clamp 110 releases the sheet P, the sheets P are stacked on the sheet processing tray 133 as already described. The above process is repeated until a predetermined number of sheets P are stacked, and when the predetermined number of sheets P are stacked, the sheet pressing portion 132 is operated to maintain the sheet stack in an aligned state, and the staple unit 134 is operated to perform the binding process. The sheet stack for which the binding process has been completed falls onto the sheet stack discharge tray 230 by the rotation of the sheet processing tray 133.

[0061] As described above, according to the first embodiment, the conveying speed of the sheet clamp 110 is sufficiently decelerated before the sheet P held by the sheet clamp 110 reaches the sheet abutment portion 131, and then the sheet clamp 110 releases the grip of the sheet P. Therefore, the conveying speed is decelerated to a speed slower than the conveying speed until the sheet P is conveyed to the sheet clamp 110 and the moving speed of the sheet clamp 110 after gripping the sheet P (the conveying speed of the sheet P), and then the grip of the sheet P is released before the sheet P abuts against the sheet abutment portion 131.

[0062] For example, the decelerated sheet clamp 110 grips and transports the sheet P, and releases the sheet clamp 110 the moment the leading edge of the sheet P reaches a predetermined position before the sheet P reaches the sheet abutment portion 131. This eliminates the phenomenon in the comparative example where the sheet P bends and bounds due to inertia in the transport direction when it collides with the sheet abutment portion 131. This improves the alignment accuracy of the sheet P.

[0063] [Second embodiment of sheet clamp transport process] Next, a second embodiment relating to the operation of the sheet clamp 110 will be described with reference to Fig. 8. Note that the flow of the operation control of the sheet clamp 110 according to this embodiment will also be described with reference to the flowchart of Fig. 11.

[0064] First, when the sheet P is conveyed and the end of the sheet P reaches a position where it can be gripped by the sheet clamp 110, the clamp drive source 115 operates so that the opening member 114 is lowered by the bias of the spring 113 (S1101). At this time, the leading edge of the sheet P is assumed to be at the position L0 (see FIG. 8(a)).

[0065] Next, the sheet clamp control unit 151 moves the sheet clamp 110 at the set moving speed (S1102). The conveying speed (V01) here may be determined according to the type of the sheet P, such as the size or thickness, or may be a uniform fixed value. This movement process continues until the conveying sensor 138 detects the end of the sheet P (end in the conveying direction) (S1103: NO).

[0066] When the conveying sensor 138 detects the end of the sheet P in the conveying direction (S1103: YES), the end of the sheet P is at the position L1. When the end of the sheet P exceeds L1, the sheet clamp control unit 151 sets the moving speed of the sheet clamp 110, that is, the conveying speed of the sheet P, to a conveying speed (V11) that is a reduced speed.

[0067] Then, the sheet clamp control unit 151 calculates the release timing of the sheet clamp 110 based on the attributes of the sheet P being transported by the sheet clamp 110. Since the transport speed (V11) after deceleration is a constant speed, the release timing corresponds to the time when the sheet clamp 110 transports the end of the sheet P in the transport direction from L1 to the distance (L21) at the transport speed (V11). Therefore, in S1103, from the time when the transport sensor 138 detects the end of the sheet P in the transport direction to the release timing, the sheet clamp 110 transports the sheet P at the transport speed (V11) after deceleration (S1104, S1105: NO).

[0068] Thereafter, when the release timing arrives (S1105: YES), the sheet clamp control section 151 releases the grip on the sheet P.

[0069] Thereafter, the conveyance direction end of the sheets P reaches the sheet abutment section 131 due to inertial force, and the sheets P are stacked on the sheet processing tray 133. The above process is repeated until a predetermined number of sheets P are stacked, and when the predetermined number of sheets P are stacked, the sheet pressing section 132 is operated to maintain the sheet stack in an aligned state, and the staple unit 134 is operated to perform the binding process. The sheet stack for which the binding process has been completed falls onto the sheet stack discharge tray 230 by the rotation of the sheet processing tray 133.

[0070] The conveying distance L21 according to this embodiment is a distance that is several millimeters shorter than the conveying distance L2 to the sheet pressing unit 132. This conveying distance L21 is set in consideration of the amount of inertia that the sheet P moves forward after the grip of the sheet P is released, so that the end of the sheet P in the conveying direction just comes into contact with the sheet abutment unit 131 when the sheet P is stacked on the sheet processing tray 133.

[0071] As described above, according to the second embodiment, the sheet clamp 110 is released when the conveying speed of the sheet clamp 110 is sufficiently decelerated and at the timing when the sheet P reaches the sheet abutment portion 131 due to inertia. This eliminates the phenomenon in the comparative example where the sheet P bends and bounds due to inertia in the conveying direction when colliding with the sheet abutment portion 131. This improves the alignment accuracy of the sheet P.

[0072] [Third embodiment of sheet clamp transport process] Next, a third embodiment relating to the operation of the sheet clamp 110 will be described with reference to Fig. 9. Note that the flow of the operation control of the sheet clamp 110 according to this embodiment will also be described with reference to the flowchart of Fig. 11.

[0073] First, when the sheet P is conveyed and the end of the sheet P reaches a position where it can be gripped by the sheet clamp 110, the clamp drive source 115 operates so that the opening member 114 is lowered by the bias of the spring 113 (S1101). At this time, the leading edge of the sheet P is assumed to be at the position L0 (see FIG. 9(a)).

[0074] Next, the sheet clamp control unit 151 moves the sheet clamp 110 at the set moving speed (S1102). The conveying speed V01 here may be determined according to the type of sheet P, such as the size or thickness, or may be a uniform fixed value. This movement process continues until the conveying sensor 138 detects the end of the sheet P (end in the conveying direction) (S1103: NO).

[0075] When the conveying sensor 138 detects the end of the sheet P in the conveying direction (S1103: YES), the end of the sheet P is at the position L1. When the end of the sheet P exceeds L1, the subsequent conveying speed V12 is calculated based on an index correlating with the weight of the sheet P, and the sheet is conveyed by the sheet clamp 110 (S1104).

[0076] The attribute weight of the sheet P can be, in addition to the type (paper type) and thickness (paper thickness) of the sheet P, a printing rate that indicates the amount of ink liquid that adheres to the sheet P when an image is formed on the sheet P in the image forming unit 120. For example, if the thickness is "300 g / m 2 " Sheet P and "80g / m 2 It is assumed that the sheet P of each of the sheets is transported at the same speed.

[0077] In this case, the thickness is 300g / m 2 The distance traveled by the inertia of the sheet P with a thickness of "80 g / m" for the sheet clamp 110 to release and stack on the sheet processing tray 133 is 2 " becomes shorter than the distance traveled by sheet P due to inertia.

[0078] Therefore, the thickness is 300g / m 2 In the case of a sheet P having a thickness of 80 g / m, the conveying speed for opening the sheet clamp 110 is set to "V12" and 2In the case of sheet P of "0.2 mm", the conveying speed for releasing the sheet clamp 110 is set to "V11". In this way, a speed is set so that the distance traveled by inertia from when the sheet clamp 110 releases the sheet P to the sheet abutment portion 131 is the same. The speed until the clamp is released is calculated by the sheet conveying speed setting portion 152 evaluating the thickness, the conveying speed V11, the distance to the sheet abutment portion 131, etc., and set in the sheet clamp control portion 151. Then, the sheet is conveyed at the set conveying speed until the timing for releasing the sheet clamp 110. In the above example, V12>V11.

[0079] As with the thickness, the distance that the sheet P lands on the sheet processing tray 133 varies depending on the type of sheet P due to inertia after release, so the transport speed is set so that this distance becomes constant.

[0080] Furthermore, when the printing rate on the sheet P is high, the sheet P does not dry sufficiently and loses stiffness. In this case, the distance that the sheet P moves due to inertia to land on the sheet processing tray 133 after the sheet clamp 110 is released is shorter than that of a sufficiently dry sheet P. That is, the position of the sheet P on the sheet processing tray 133 varies depending on the printing rate, and the degree of alignment of the edges decreases. Therefore, the speed at which the sheet P is conveyed by the sheet clamp 110 is set so that the position of the sheet P on the sheet processing tray 133 is constant regardless of the printing rate.

[0081] It is assumed that the type, thickness, and printing rate of the sheet P are in a state that can be recognized in advance by the control unit 150 in accordance with the sheet P to be conveyed. Also, information on the type, thickness, and the like of the sheet P may be stored in advance in a storage unit of the MFP 1, and the sheet clamp control unit 151 may read and use the information.

[0082] As described above, the sheet clamp control unit 151 calculates the conveying speed (V12) of the sheet P after deceleration by the sheet clamp 110 based on the attribute of the sheet P being conveyed by the sheet clamp 110. Then, the timing at which the sheet clamp 110 conveys the sheet P to a point of the conveying distance L23 corresponding to the release timing at the calculated conveying speed (V12) corresponds to the release timing as in the second embodiment. Therefore, the sheet clamp 110 conveys the sheet P at the conveying speed (V12) from the timing at which the conveying sensor 138 detects the end of the sheet P in the conveying direction until the release timing (S1104, S1105: NO).

[0083] Thereafter, when the release timing arrives (S1105: YES), the sheet clamp control section 151 releases the grip on the sheet P.

[0084] Thereafter, the conveyance direction end of the sheets P reaches the sheet abutment section 131 due to inertial force, and the sheets P are stacked on the sheet processing tray 133. The above process is repeated until a predetermined number of sheets P are stacked, and when the predetermined number of sheets P are stacked, the sheet pressing section 132 is operated to maintain the sheet stack in an aligned state, and the staple unit 134 is operated to perform the binding process. The sheet stack for which the binding process has been completed falls onto the sheet stack discharge tray 230 by the rotation of the sheet processing tray 133.

[0085] As described above, according to the third embodiment, the conveying speed of the sheet clamp 110 is calculated according to an index that affects the inertia of the sheet P to be conveyed, and the sheet clamp 110 is released in a state in which the conveying speed is decelerated to that speed and at the timing when the sheet P reaches the sheet abutment portion 131 due to inertia. This eliminates the phenomenon in the comparative example in which the sheet P bends and bounds due to inertia in the conveying direction when colliding with the sheet abutment portion 131. This improves the alignment accuracy of the sheet P.

[0086] [Fourth embodiment of sheet clamp transport process] Next, a fourth embodiment relating to the operation of the sheet clamp 110 will be described with reference to Fig. 10. Note that the flow of the operation control of the sheet clamp 110 according to this embodiment will also be described with reference to the flowchart of Fig. 11.

[0087] First, when the sheet P is conveyed and the end of the sheet P reaches a position where it can be gripped by the sheet clamp 110, the clamp drive source 115 operates so that the opening member 114 is lowered by the bias of the spring 113 (S1101). At this time, the leading edge of the sheet P is assumed to be at the position L0 (see FIG. 10(a)).

[0088] Next, the sheet clamp control unit 151 moves the sheet clamp 110 at the set moving speed (S1102). The conveying speed V01 here may be determined according to the type of sheet P, such as the size or thickness, or may be a uniform fixed value. This movement process continues until the conveying sensor 138 detects the end of the sheet P (end in the conveying direction) (S1103: NO).

[0089] When the conveying sensor 138 detects the end of the sheet P in the conveying direction (S1103: YES), the end of the sheet P is at the position L1. When the end of the sheet P exceeds L1, the subsequent conveying distance L22 is calculated based on an index correlating with the weight of the sheet P, and the sheet is conveyed by the sheet clamp 110 (S1104).

[0090] The indexes correlated with the weight of the sheet P include the type (paper type) and thickness (paper thickness) of the sheet P, as well as a printing rate that indicates the amount of ink liquid that adheres to the sheet P when an image is formed on the sheet P in the image forming unit 120. For example, when the thickness is "300 g / m 2 " Sheet P and "80g / m 2 It is assumed that the sheet P in the "1" position is transported at the same transport speed V11 and released at the same timing.

[0091] In this case, the thickness is 300g / m 2 The distance that a sheet P with a thickness of 80 g / m travels due to inertia after the sheet clamp 110 is released and before the sheet P lands on the sheet processing tray 133 is2 " becomes shorter than the distance traveled by sheet P due to inertia.

[0092] Therefore, the thickness is 300g / m 2 In the case of a sheet P having a thickness of 80 g / m, the release timing of the sheet clamp 110 is set to a distance of "L22". 2 In the case of the sheet P, the distance is set to "L21" as in the third embodiment. Note that L22 is longer than L21.

[0093] In this way, by releasing the sheet P with the timing at which the sheet clamp 110 releases the sheet P in accordance with an index related to the sheet P, the release timing is set so that the distance that the sheet P advances by inertia from when it is released to the sheet abutment portion 131 is the same. The release timing adjustment portion 153 evaluates and calculates the thickness, the conveying speed (V11), the distance to the sheet abutment portion 131, etc., and sets the timing to release the clamp in the sheet clamp control portion 151. Then, the sheet is conveyed at the set conveying speed until the release timing of the sheet clamp 110. In the above example, L22>L21.

[0094] As with the thickness, the distance that the sheet P lands on the sheet processing tray 133 varies depending on the type of sheet P due to inertia after release, so the release timing is set so that this distance becomes constant.

[0095] Furthermore, when the printing rate of the sheet P is high, the sheet P does not dry sufficiently and loses stiffness. In this case, the distance that the sheet P moves due to inertia to land on the sheet processing tray 133 after the sheet clamp 110 is released is shorter than that of a sufficiently dry sheet P. That is, the position of the sheet P on the sheet processing tray 133 varies depending on the printing rate, and the degree of alignment of the edges decreases. Therefore, the timing of opening by the sheet clamp 110 is adjusted and set so that the position of the sheet P on the sheet processing tray 133 is constant regardless of the printing rate.

[0096] It is assumed that the type, thickness, and printing rate of the sheet P are in a state that can be recognized in advance by the control unit 150 in accordance with the sheet P to be conveyed. Also, information on the type, thickness, and the like of the sheet P may be stored in advance in a storage unit of the MFP 1, and the sheet clamp control unit 151 may read and use the information.

[0097] As described above, the sheet clamp control unit 151 calculates the timing for releasing the sheet P by the sheet clamp 110 based on an index correlating with the weight of the sheet P being transported by the sheet clamp 110, and transports the sheet P at a transport speed similar to that of the second or third embodiment based on the calculated release timing, up to a distance (L22) (S1104, S1105: NO).

[0098] When the end portion of the sheet P in the conveying direction has moved to the distance (L21) (S1105: YES), the sheet clamp control portion 151 releases the grip of the sheet P.

[0099] Thereafter, the conveyance direction end of the sheets P reaches the sheet abutment section 131 due to inertial force, and the sheets P are stacked on the sheet processing tray 133. The above process is repeated until a predetermined number of sheets P are stacked, and when the predetermined number of sheets P are stacked, the sheet pressing section 132 is operated to maintain the sheet stack in an aligned state, and the staple unit 134 is operated to perform the binding process. The sheet stack for which the binding process has been completed falls onto the sheet stack discharge tray 230 by the rotation of the sheet processing tray 133.

[0100] As described above, according to the third embodiment, the conveying speed of the sheet clamp 110 is calculated according to an index that affects the inertia of the sheet P to be conveyed, and the sheet clamp 110 is released in a state in which the conveying speed is decelerated to that speed and at the timing when the sheet P reaches the sheet abutment portion 131 due to inertia. This eliminates the phenomenon in the comparative example in which the sheet P bends and bounds due to inertia in the conveying direction when colliding with the sheet abutment portion 131. This improves the alignment accuracy of the sheet P.

[0101] Here, an example of control in which the sheet clamp 110 releases the grip of the sheet P at a predetermined position without using the conveyance sensor 138 in the control operation according to each of the above embodiments is shown. For example, a time T1 required for the sheet clamp 110 to move the distance from the position where the sheet P is gripped to the sheet abutting portion 131 at a conveyance speed (V01) described later is calculated. The time T1 is set in a timer possessed by the control unit 150, and when the remaining time on the timer reaches time T2, which is half of the time T1, the conveyance speed is decelerated to a decelerated conveyance speed (V11, V12). As described above, the deceleration of the sheet P and the release operation of the sheet clamp 110 can also be controlled by the detection timing of the sheet P by the first sheet detection sensor 250 and the distance of each member of the movement mechanism that moves the sheet clamp 110.

[0102] The present invention is not limited to the above-described embodiment, and various modifications are possible without departing from the gist of the present invention, and all technical matters included in the technical ideas described in the claims are the subject of the present invention. The above-described embodiment shows a preferred example, but a person skilled in the art can realize various alternatives, modifications, variations, or improvements from the contents disclosed in this specification, and these are included in the technical scope described in the attached claims. [Explanation of symbols]

[0103] 1:MFP 10: Post-processing unit 11: Delivery route 30: Image reading unit 31: Automatic transport device 110: Seat clamp 111: Clamp bar 112: Clamp arm 113: Spring 114: Opening member 115: Clamp drive source 120: Image Formatting Section 121: First clamp moving roller 122: Second clamp moving roller 123: Clamp moving belt 131: Sheet abutment part 132: Sheet holding part 133: Sheet processing tray 134: Staple unit 135: Support member 136: Arm member 138: Transport sensor 150: Control section 151: Sheet clamp control section 152: Sheet transport speed setting unit 153: Release timing adjustment section 154: Sheet detection unit 211: Sheet supply cassette 212: Separation roller 213: Friction pad 214: Sheet supply roller pair 215: Sheet conveying roller pair 216: Discharge roller pair 220: Image forming unit 221: Cartridge loading section 222: Ink cartridge 230: Sheet stack discharge tray 240: Sheet ejection tray 250: First sheet detection sensor 2161: Post-processing conveying roller pair [Prior art documents] [Patent documents]

[0104] [Patent Document 1] JP 2014-156334 A

Claims

1. A sheet processing apparatus that performs post-processing on a sheet, a sheet alignment mechanism for aligning an edge of the stacked sheets in a conveying direction; a sheet gripping and conveying mechanism that grips the sheet and conveys the sheet to the sheet alignment mechanism; a sheet detection sensor that detects when the end portion of the sheet being aligned by the sheet alignment mechanism approaches the sheet alignment mechanism by a certain distance or less; Equipped with The sheet gripping and conveying mechanism includes: When the sheet detection sensor detects the edge, a conveying speed to the sheet alignment mechanism is reduced to convey the sheet, When the grip on the sheet being conveyed at the decelerated conveying speed is released, the grip is released at a predetermined timing at which the end portion of the sheet can move until it abuts against the sheet aligning mechanism due to an inertial force acting on the sheet based on an attribute of the sheet. A sheet processing apparatus comprising:

2. the sheet gripping and conveying mechanism sets the conveying speed until the grip of the sheet is released based on the attribute. The sheet processing apparatus according to claim 1 .

3. the attribute is at least one of or a combination of a size of the sheet, a thickness of the sheet, and an amount of imaging material applied to the sheet; The sheet processing apparatus according to claim 1 .

4. a sheet stacking section for stacking the sheet stack conveyed by the sheet gripping and conveying mechanism; 4. The sheet processing apparatus according to claim 1, further comprising: a sheet stack holding mechanism that holds an edge aligned state of a sheet stack formed by a plurality of sheets whose edges have been aligned by the sheet alignment mechanism and stacked on the sheet stacking section.

5. An image forming apparatus including an image forming unit that forms an image on a sheet, and a post-processing device that performs post-processing on the sheet on which the image has been formed, 5. An image forming apparatus, wherein the post-processing device is the sheet processing device according to claim 1.

6. the image forming unit forms an image by applying a liquid as an image forming material to the sheet; The image forming apparatus according to claim 5 .

Images