JP3907335B2 - Sheet stacking device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a sheet stacking apparatus capable of moving a stacking unit up and down.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, there is a finisher that performs a binding process on sheets discharged from an image forming apparatus such as a copying machine and stacks the sheets on a stack tray. The finisher stacks the sheets discharged from the image forming apparatus on the intermediate processing tray, and when a bundle of sheets is stacked on the intermediate processing tray, the stapler unit staples the sheets on the intermediate processing tray. The sheet bundle on the intermediate processing tray is discharged to the stack tray by a bundle discharge roller or a bundle discharge belt. Each time a sheet bundle is discharged to the stack tray, the stack tray is lowered, and when the sensor detects the upper surface of the sheet on the stack tray, the stack tray is raised by a predetermined amount. Thereby, it is possible to control the upper surface of the sheets stacked on the stack tray so as to have a height suitable for bundle discharge.
[0003]
In order to further reduce the size of such a conventional finisher, it is considered to shorten the intermediate processing tray. In order to shorten the intermediate processing tray, a configuration in which sheets are scooped on the stacking surface of the stack tray when a large size sheet is discharged to the intermediate processing tray can be considered. In this case, if the distance between the stack tray stacking surface and the intermediate processing tray is too short, the stack tray stacking surface may interfere with discharge during discharge to the intermediate processing tray, and sheet jam may occur. Therefore, the distance between the stack tray loading surface and the intermediate processing tray must be an appropriate distance.
[0004]
[Problems to be solved by the invention]
However, if the above-mentioned control is performed, when the lower limit is reached while the stack tray is being lowered, it is before the sensor detects the upper surface of the sheet, so the amount of increase after reaching the lower limit is set to the predetermined amount. Then, the distance between the upper surface of the sheet and the intermediate processing tray becomes too short, and there is a possibility that a sheet jam occurs when the sheet is discharged to the intermediate processing tray.
[0005]
[Means for Solving the Problems]
In order to solve the above-described problem, the present invention provides a stacking unit that can move up and down to stack discharged sheets, and a first unit that detects that an upper surface of a sheet stacked on the stacking unit is positioned at a predetermined height. Detecting means, elevating means for raising and lowering the stacking means, and detecting that the upper surface of the sheet is positioned at a predetermined height by the first detecting means in response to the discharge of the sheet to the stacking means And a control means for controlling the elevating means to lower the stacking means until the stacking means is raised by a predetermined amount, and a second detection means for detecting that the stacking means has reached a lower limit. The control means responds to the fact that the second detecting means detects that the lower limit of the stacking means has been reached before the first detecting means detects the upper surface of the sheet while the stacking means is being lowered. , Descent of the loading means The sheet stacking apparatus is characterized in that the operation is stopped and the elevating means is controlled so as not to raise the stacking means, and when there is a sheet to be discharged when the lower limit is detected, the sheet stacking is continued. Is to provide.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
The sheet processing apparatus according to the present exemplary embodiment is mounted on an image forming apparatus and processes sheets discharged from the image forming apparatus. First, the image forming apparatus main body will be described. FIG. 1 is a diagram illustrating the configuration of an image forming apparatus and a sheet processing apparatus. The image forming apparatus includes an image reader 200 and a printer 300, and the document feeder 100 is mounted on the image reader 200. The document feeder 100 separates the documents set upward, feeds them one by one to the left sequentially from the first page, conveys them onto the platen glass 102 through a curved path, and reads the document. After that, the paper is discharged to the paper discharge tray 112. Reading is performed by irradiating the light from the lamp 103 of the scanner unit 104 onto the original and reflecting light from the original through the mirrors 105, 106, 107 and the lens 108 to the image sensor 109.
[0007]
The document image read by the image sensor 109 is subjected to image processing and sent to the exposure control unit 110. The exposure control unit 110 outputs laser light corresponding to the image signal. The laser beam is irradiated onto the photosensitive drum 111, and an electrostatic latent image is formed on the photosensitive drum 111. The electrostatic latent image on the photosensitive drum 111 is developed by the developing unit 113, and the developer on the photosensitive drum 111 is applied to the sheet fed from any of the cassettes 114 and 115, the manual sheet feeding unit 125, and the duplex conveyance path 124. The image is transferred by the transfer unit 116.
[0008]
The sheet onto which the developer has been transferred is subjected to a developer fixing process in the fixing unit 117. The sheet that has passed through the fixing unit 117 is once guided to the path 122 by the flapper 121, and after the trailing edge of the sheet has passed through the flapper 121, the sheet is switched back and guided to the discharge roller 118 by the flapper 121. As a result, the surface onto which the developer has been transferred is discharged from the printer 300 by the discharge roller 118 in a downward state (face down). This is called reverse paper discharge. By discharging face down, the correct page order is obtained when images are formed in order from the first page, such as when the document feeder 100 is used or when an image output from a computer is printed.
[0009]
When an image is formed on the hard sheet such as an OHP sheet from the manual sheet feeding unit 125, the surface onto which the developer is transferred is discharged from the discharge roller 118 in an upward state (face-up) without being guided to the path 122. Further, when copying one single-sided original, copying one double-sided original on both sides of a sheet, or copying two single-sided originals on both sides of a sheet, the sheets are discharged face-up. The sheet discharged from the discharge roller 118 is sent to the finisher 400. The finisher 400 performs a binding process and the like.
[0010]
When images are formed on both sides of the sheet, the sheet that has passed through the fixing unit 117 is guided to the path 122 by the flapper 121 and switched back to the duplex conveying path 124.
[0011]
As shown in FIG. 2A, the original is read from the right end toward the left end in the sub-scanning direction. The read image is as shown in FIG. 2B, and after this is rotated 180 degrees as shown in FIG. 2C, an image is formed on the sheet as shown in FIG. 2D. Then, as shown in FIG. 2E, the sheet on which the image is formed is reversed and discharged, and the back side is bound. That is, the upper left of the image is bound. The main scanning direction of the image sensor 109 and the exposure control unit 110 is a direction indicated by an arrow.
[0012]
FIG. 3 shows a block diagram for controlling the above-described apparatus. The CPU circuit unit 150 includes a CPU, and the document feeder control unit 101, the image reader control unit 201, the image signal control unit 202, the printer control unit 301, according to the program stored in the ROM 151 and the setting of the operation unit 1. It manages the finisher control unit 401 and the external I / F 203. The document feeder controller 101 controls the document feeder 100, the image reader controller 201 controls the image reader 200, the printer controller 301 controls the printer 300, and the finisher controller 401 controls the finisher 400. The RAM 152 is used as an area for temporarily holding control data and a work area for computations associated with control. An external I / F 203 is an interface from the computer 204 and develops print data into an image and outputs it to the image signal control unit 202. An image read by the image sensor 109 is output from the image reader control unit 201 to the image signal control unit 202, and an image output from the image signal control unit 202 to the printer control unit 301 is input to the exposure control unit 110.
[0013]
FIG. 4 shows the configuration of the image signal control unit 202. The image processing unit 205 performs image correction processing and editing processing according to the setting in the operation unit 1. The image is output to the printer control unit 301 via the line memory 206 and the page memory 207. The hard disk 208 is used as necessary when changing the page order.
[0014]
FIG. 5 shows the configuration of the finisher 400. The sheet received from the printer 300 is sent to the paper discharge roller 415 via the path 416, and the paper discharge roller 415 is discharged onto the bundle paper discharge belt 421 (FIG. 20). A low-friction intermediate processing tray (not shown) is provided at a position several millimeters higher in parallel with the bundled paper discharge belt 421, and the sheet is accurately placed on the intermediate processing tray. The paper feed guides 413 and 414 are plate-like rocking members and hang down by their own weights, and press down the sheet discharged by the paper discharge roller 415. The discharged sheet falls in the lower right direction along an intermediate processing tray (bundle discharge belt 421) provided obliquely (FIG. 21). As the fan-shaped return roller 417 rotates counterclockwise, the friction member provided on the arc of the return roller 417 comes into contact with the sheet discharged onto the bundle discharge belt 421, and the friction member moves the sheet in the lower right direction. The end of the sheet is brought into contact with the stopper plate 418 (FIG. 22). The staple unit 419 is provided on the back side, and staples the sheets on the bundle discharge belt 421. Since the length of the bundle discharge belt 421 may not be sufficient for stacking sheets, the intermediate processing tray stacking auxiliary plate 421B is provided on the bundle discharge belt 421 to increase the length of the sheet stacking surface in the intermediate processing tray. . The alignment plates 412 are provided on the front side and the back side, and align the sheets on the bundle delivery belt 421 (FIG. 23). Further, it is possible to perform offset stacking in which the state stacked on the stack tray 411 by the alignment plate 412 is distributed to the near side and the far side (FIG. 24).
[0015]
The sheets on the bundle discharge belt 421 are discharged onto the stack tray 411 by a bundle discharge lever 421A provided on the bundle discharge belt 421. The bundle delivery lever 421A rotates the bundle delivery belt 421 counterclockwise to push the sheet upward and eject it onto the stack tray 411 (FIG. 25). The bundle discharge lever 421A moves in a notch provided in the intermediate processing tray. The stack tray 411 moves up and down according to the sheet stacking amount. Further, by lowering the stack tray 411 until the upper surface of the sheet on the stack tray 411 is positioned below the paper pressing lever 420, the upper surface of the sheet is pressed by the paper pressing lever 420 and then stacked. This prevents the sheet discharged on the tray 411 from being pushed leftward.
[0016]
FIG. 6 is a diagram for explaining the sensors and motors in the finisher 400. The motor M1 drives the paper discharge roller 415, and the motor M2 drives the return roller 417 and the bundle paper discharge belt 421. The bundle delivery belt 421 is driven by a motor M2 via a one-way clutch 422. When the motor M2 rotates in the reverse direction, only the return roller 417 rotates counterclockwise. When the motor M2 rotates in the forward direction, the return roller 417 rotates clockwise and the bundle discharge belt 421 rotates counterclockwise. FIG. 7 shows this perspective view. When the motor rotates in the black arrow direction, each part rotates in the black arrow direction, and when the motor rotates in the white arrow direction, each part rotates in the white arrow direction. In this way, the return roller 417 and the bundle discharge belt 421 are driven by one motor, so that the cost can be reduced.
[0017]
Further, whether or not the return roller 417 is at the home position is detected by the sensor S3. Further, the sheet discharge roller 415 is activated in response to the sensor S2 detecting the leading edge of the sheet, and the sheet discharge roller 415 is decelerated at a timing described later and then stopped. The sensor S5 detects a sheet on the bundle discharge belt 421, and the sensor S11 detects a sheet on the stack tray 411. The sensor S8 detects whether or not the bundle discharge lever 421A is at the home position. The positions of the return roller 417 and the bundle discharge lever 421A in FIG. 6 are home positions.
[0018]
The return roller 417 in FIG. 6 rotates exactly one turn leftward from the home position every time a sheet is discharged. When the return roller 417 is rotating counterclockwise, the bundle discharge belt 421 does not rotate as described above. Further, the home position of the bundle discharge lever 421A is slightly to the right of the stopper plate 418. However, if the sheets on the bundle discharge belt 421 are to be discharged in a bundle as they are, the return roller 417 and the bundle discharge belt 421 at the home position are driven, and the return roller 417 and the bundle discharge belt 421 are driven. The sheet bundle comes into contact with the sheet bundle, which prevents the bundle from being discharged. Therefore, the return roller 417 is rotated by 1/8 in the left direction and then (1 + 1/8) in the right direction so that the return roller 417 follows the bundle discharge lever 421A. In addition, when the return roller 417 is rotated to the right (1 + 1/8), the bundled paper discharge belt 421 is rotated 1/2 in the left direction. As shown in the figure, two bundle delivery levers 421A are provided at equal intervals on the bundle delivery belt 421, and stop at the home position again by a half turn.
[0019]
When the sheet is discharged from the sheet discharge roller 415 when the bundle is not discharged next, the return roller 417 is rotated once in the left direction. However, the sheet is discharged from the sheet discharge roller 415 when the bundle is discharged next time. When the return roller 417 is discharged, the return roller 417 is further rotated 1/8 to the left without being stopped when it is rotated once in the left direction, and is rotated to the right as described above. Thereby, the processing time at the time of bundle discharge | emission can be shortened.
[0020]
Further, when the bundle is discharged, the bundle discharge belt 421 is rotated by half, but if it is rotated by half as it is, the bundle discharge lever 421A hits the sheet bundle stacked on the stack tray 411. This is because the stack tray 411 is controlled to a position suitable for dropping of the sheet bundle during bundle discharge, and the upper surface of the sheet bundle stacked on the stack tray 411 in this state is the bundle discharge lever 421A. It will be on the orbit of the. Therefore, when the bundle delivery lever 421A is substantially parallel to the straight portion of the bundle delivery belt 421 shown in FIG. 8 (substantially parallel to the intermediate processing tray (not shown)), the bundle delivery belt 421 (motor M2) is temporarily stopped. Then, when the stack tray 411 is lowered, the remaining rotation is performed to stop at the home position. This prevents the bundle discharge lever 421A from winding the sheets on the stack tray 411 and prevents the trailing edge of the sheet bundle from remaining on the bundle discharge belt 421. This operation corresponds to the case where the motor M2 is temporarily stopped at the time of reverse rotation (descent) of * 2 performed at the third and fourth times of the motor M5 in FIGS. That is, the return roller 417 rotates (1 + 1/8) in the left direction at * 16 in FIGS. 11 and 12, and the return roller 417 rotates (1 + 1/8) in the right direction at * 17 + * 18. Rotates 1/2 turn.
[0021]
FIG. 9 is a view for explaining a driving mechanism of the alignment plate 412. The alignment plate 412A is provided on the front side, and the alignment plate 412B is provided on the back side. The motor M3 drives the alignment plate 412A, and the motor M4 drives the alignment plate 412B. When the motor rotates in the black arrow direction, each part rotates in the black arrow direction, and when the motor rotates in the white arrow direction, each part rotates in the white arrow direction. Sensor S6 is provided for detecting the home position of alignment plate 412A, and sensor S7 is provided for detecting the home position of alignment plate 412B. When stapling is performed by the staple unit 419, the alignment plate 412B is set to the farthest side, and the alignment plate every time the sheet is discharged onto the bundle discharge belt 421 so as to abut the alignment plate 412B. 412A is pressed against the sheet. When performing offset paper discharge without stapling, the sheet is abutted against one of the alignment plates 412A and 412B with the alignment plates 412A and 412B being set at a distance corresponding to the sheet width. Accordingly, each time the sheet is discharged onto the bundle discharge belt 421, the other of the alignment plates 412A and 412B is pressed against the sheet. At the time of offset discharge, the alignment plates 412A and 412B are alternately shifted to the front side, the back side, the front side, the back side, and so on each time a bundle discharge is performed, thereby loading the stack tray 411. The sheet bundle to be set is in an offset (shifted) state for each bundle (FIG. 24).
[0022]
Note that the user can appropriately set whether or not the offset paper is discharged from the operation unit of the image forming apparatus, and the setting content is notified from the image forming apparatus to the finisher 400, and the finisher 400 responds accordingly. Operate.
[0023]
Here, the drive timing of the alignment plate 412 and the return roller 417 will be described. As described above, the return roller 417 moves the sheet in the sheet discharging direction, and the alignment plate 412 acts to move the sheet in a direction perpendicular to the sheet discharging direction. Thus, since the return roller 417 and the alignment plate 412 act in different directions, if the operations of the two overlap, the sheet is adversely affected. Therefore, when the operation * 16 of M2 (return roller 417) in FIGS. 11 and 12 is completed, the operation * 14 of M4 (alignment plate 412) is started. Thereby, the alignment plate 412 can be operated in a state where the return roller 417 is not in contact with the sheet, and adverse effects on the sheet can be prevented.
[0024]
FIG. 10 is a view for explaining the lifting mechanism of the stack tray 411. The motor M5 raises and lowers the stack tray 411 and drives the paper pressing lever 420. Sensor S13 detects that stack tray 411 has reached the upper limit, and sensor S12 detects that stack tray 411 has reached the lower limit. The flag 423 is pushed inward when the sheets stacked on the stack tray 411 come into contact, and the height of the sheet can be detected by detecting the flag 423 pushed in by the sensor S10. When the motor rotates in the black arrow direction, each part rotates in the black arrow direction, and when the motor rotates in the white arrow direction, each part rotates in the white arrow direction. The paper pressing lever 420 is retracted from the stack tray 411 when the stack tray 411 is lowered, and protrudes above the stack tray 411 when the stack tray 411 is raised, and presses the sheet on the stack tray 411.
[0025]
As described above, the stack tray 411 is lowered when the bundle is discharged, so that the bundle discharge lever 421A is not in contact with the sheet on the stack tray 411, and the sheet pressing lever 420 is newly discharged. This is because it is positioned at the upper part of the sheet bundle. When the stack tray 411 is lowered and then raised, the upper part of the newly discharged sheet bundle can be pressed by the paper pressing lever 420.
[0026]
FIG. 11 shows an operation timing chart of each unit when two copies of two originals are copied and offset discharge (without binding processing) is performed by the finisher 400. FIG. 12 shows an operation timing chart of each part when two copies of two originals are copied and the binding process is performed by the finisher 400. In the motor timing chart, the black band indicates normal rotation, and the hatched band indicates reverse rotation. * 1 indicates the number of copies on the left side and the number of originals on the right side of the hyphen. * 2 reverses (lowers) until the sensor S10 that detects the sheet height of the stack tray is turned off. In * 3, normal rotation is performed until the sensor S8 for detecting the home position of the bundle discharge lever is turned on, and in * 4, reverse rotation is performed until the sensor S3 for detecting the home position of the return roller is turned on. In * 5, the sheet rotates forward (up) until the sensor S10 for detecting the sheet height of the stack tray is turned on. In * 8, it reverses (drives outward) until the sensor S6 that detects the home position of the alignment plate is turned on. In * 9, the rotation is reversed (driven outward) until the sensor S7 for detecting the home position of the alignment plate is turned on. In * 10, the alignment plate 412 is rotated forward (driven inward) to move to the standby position. * 14 and 15, the alignment plate 412 is moved inward to the sheet width and then reversely and normally rotated so as to return to the standby position. * 16: In order to prevent the return roller 417 and the sheet bundle from interfering when the bundle is discharged, the drive continues to rotate backward (without pausing) after the return roller 417 reaches the home position. To do. In * 18, normal rotation is performed until the sensor S8 for detecting the home position of the sensor bundle discharge lever is turned on. In * 19, the return roller 417 is turned on a predetermined time after it is turned off.
[0027]
FIG. 13 shows a flowchart of drive control of the paper discharge roller 415 in the finisher 400. As shown in FIG. 6, when the finisher 400 is provided in a compact manner, the distance between the paper discharge roller 415 and the sensor S2 is shortened. On the other hand, considering the stackability when the paper discharge roller 415 discharges onto the bundle paper discharge belt 421, the paper discharge roller 415 kicks out vigorously while the sheet is being discharged, and the trailing edge of the sheet exits the paper discharge roller 415. At this point, it is desirable to prevent the sheet from jumping over the bundled sheet discharge belt 421 by decelerating the sheet discharge roller 415. Normally, when decelerating based on the trailing edge, a method of decelerating in response to detection of the trailing edge of the sheet is employed. However, when the distance between the discharge roller 415 and the sensor S2 is short as described above, Even if it is possible to prevent the sheets from jumping over the bundle delivery belt 421, it may not be sufficient to improve the stackability. Therefore, the following control is performed in order to obtain better loadability with a compact finisher.
[0028]
The finisher 400 (finisher control unit 401) receives the size information of each sheet from the image forming apparatus (CPU circuit unit 150). First, it is determined whether or not the size of the sheet to be discharged by the paper discharge roller 415 is a standard size (S101). When the size is the standard size, the sensor S2 is turned on (the leading edge of the sheet passes) (S102), the drive (motor M1) of the paper discharge roller 415 is turned on (S103), and the amount according to the sheet size It is determined whether the paper discharge roller 415 has been rotated (S104). The motor M1 is a step motor, and the amount of rotation is always managed by the finisher control unit 401. In response to the rotation according to the sheet size, the paper discharge roller 415 is decelerated (S105) and stopped (S106). The rotation amount in step S104 is set in consideration of the sheet size and the deceleration time of the paper discharge roller 415 so that the trailing edge of the sheet comes out immediately before the paper discharge roller 415 stops in step S106. As a result, the discharged sheets do not fly too much on the bundle discharge belt 421.
[0029]
On the other hand, when it is determined in step S101 that the sheet is not a standard size, that is, a free size sheet, in response to the sensor S2 being turned on (the leading edge of the sheet has passed) (S107), the drive of the paper discharge roller 415 is turned on (S107). S108). Then, in response to the sensor S2 being turned off (the trailing edge of the sheet has passed) (S109), the paper discharge roller 415 is decelerated (S110) and stopped (S111). However, if the position of the sensor S2 shown in FIG. 6 is reached, the trailing edge of the sheet comes off before it is sufficiently decelerated in step S110. Although this timing is not sufficient as stackability, the sheet does not jump over the bundled paper discharge belt 421. If the sensor S2 is arranged further upstream, the stackability is improved, but the sensor S2 cannot be moved upstream because it is also used for sheet jam detection. Although it is sufficient to increase another sensor while maintaining the position of the sensor S2, the cost increases. Thus, in order to improve the performance as much as possible at low cost, only one sensor is provided in the path 416 and the control as shown in FIG. 13 is performed.
[0030]
FIG. 14 is a flowchart relating to the control of the intermediate processing tray in the finisher 400, particularly the bundle discharge control by the bundle discharge belt 421. First, as an initial operation before the image forming operation, it is determined based on the sensor S5 whether there is a sheet on the bundled paper discharge belt 421 (intermediate tray) (S121). If there is a sheet on the bundle discharge belt 421, it is determined whether or not the sheet is the second original sheet (S122). The second original drawing sheet is a thin and thin sheet used for drafting and the like. When the setting to use the manual sheet feeding unit 125 in FIG. 1 is made on the image forming apparatus side, the screen of the operation unit of the image forming apparatus is in the state shown in FIG. 15B. It will be in the state of 15 (c). By pressing the second original drawing key on this screen, it is considered that the second original drawing sheet is fed from the manual sheet feeding unit 125, and when the sheet is transferred from the image forming apparatus to the finisher 400, the image forming apparatus transfers to the finisher 400. The material information and the paper feed unit information are notified in association with the sheet. Thus, the finisher 400 can determine whether the sheet on the bundle discharge belt 421 is the second original sheet. FIG. 15A is a screen of the operation unit during normal standby in the copy mode, and displays the number of image forming copies set in the operation unit.
[0031]
When it is determined in step S122 that the sheet is not the second original drawing sheet, the bundle discharge belt 421 is driven to discharge the bundle (S123), and a standby signal is output to the image forming apparatus (S126). If it is determined that the sheet is the second original sheet, an intermediate processing tray overflow signal is output to the image forming apparatus (S124). The image forming apparatus that has received the intermediate processing tray overflow signal displays “Please remove the sheet from the intermediate processing tray” on the operation unit. Then, it waits until there is no sheet on the bundled paper discharge belt 421 (intermediate tray) (S125), and when there is no sheet, a standby signal is output to the image forming apparatus (S126). If there is no sheet on the bundle delivery belt 421 in step 121, a standby signal is output to the image forming apparatus (S126). In response to the standby signal from the finisher 400, the image forming apparatus starts image formation on the sheet.
[0032]
After outputting the standby signal in step S126, each of the variables S, N, and T is set to 0 (S127). Variables S and N are variables for monitoring so as not to overload the intermediate processing tray. The variable T is a variable for preventing the sheets on the stack tray 411 from being adversely affected by static electricity charged on the OHP when the OHP sheet is discharged. Next, the material type information of the sheet discharged from the image forming apparatus is received, and it is determined whether or not it is the second original drawing (S128).
[0033]
If it is determined in step S128 that it is not the second original drawing, the following processing is performed. The sheet received from the image forming apparatus is discharged onto the bundle discharge belt 421 (S129), and a weighting count for a variable S described later is performed (S130). Then, the size information of the next received sheet is received from the image forming apparatus, and it is determined whether or not the width of the sheet already stacked on the bundle delivery belt 421 is different from the width of the next received sheet (S131). If the widths do not differ, it is next determined whether or not the image forming job setting for the currently received sheet is the non-staple mode (S132). If it is in the non-staple mode, it is determined whether or not the sheet discharged onto the bundled paper discharge belt 421 in step S129 is fed from the manual paper feed unit 125 (S133). If the sheet is fed from the manual sheet feeder 125, 1 is added to the variable T (S134), and it is determined whether the variable T is 5 (S135). When the variable T becomes 5, that is, when five sheets are continuously fed from the manual sheet feeder 125, the bundle delivery belt 421 is driven to perform bundle delivery (S136), and the job If not completed (S156), the process returns to step S129. If the sheet is not fed from the manual sheet feeder 125 in step S133, the variable T is set to 0 (S137), and the process proceeds to step S138 described later. If the variable T is not 5 in step S135, the process proceeds to step S138 described later.
[0034]
The manual sheet feeder 125 is designed to feed various types of sheets including OHP sheets. OHP sheets are more susceptible to static electricity than ordinary paper. Therefore, even if 30 sheets of ordinary paper are collectively bundled and discharged from the bundle discharge belt 421 to the stack tray 411, even if the sheets on the stack tray 411 are not adversely affected, only 30 OHP sheets are collectively bundled and discharged. Then, the sheet on the stack tray 411 may be shifted due to the synergistic effect of the weight and static electricity. In view of this, when five sheets fed from the manual sheet feeding unit 125 where the OHP sheet may be fed are consecutive, bundle ejection is performed to prevent this.
[0035]
If the width of the sheet stacked on the bundle delivery belt 421 is different from the width of the next received sheet in step S131, the process advances to step S136 to perform bundle delivery. If it is determined in step S132 that the mode is not the non-staple mode, that is, the staple mode, it is determined whether or not the variable S is 60 or more (S138). If the variable S is not 60 or more, that is, less than 60, it is determined whether or not it is a break line based on a job break signal from the image forming apparatus (S140). If it is a job break, the flow advances to step S136 to discharge the bundle. If it is determined in step S138 that the variable S is 60 or more, the current stapling is prohibited (S139), and the flow advances to step 136 to discharge the bundle.
[0036]
On the other hand, when it is determined in step S128 that the sheet is the second original sheet, the sheet received from the image forming apparatus is discharged onto the bundle discharge belt 421 (S141), and 1 is added to the variable N (S142). Then, a weighting count is performed for the variable S (S143), and it is determined whether the variable N has become 15 (S144). If the variable N is not 15, it is determined whether or not the variable S is 60 or more (S145). If the variable S is not 60 or more, it is determined whether or not it is a break based on a job break signal from the image forming apparatus (S146). If it is not a job break, the process returns to step S141. Further, when it is a job break, an intermediate processing tray overflow signal is output to the image forming apparatus (S147), and as described above, the image forming apparatus displays to remove the sheet on the intermediate processing tray.
[0037]
Since the second original drawing sheet is weak and not suitable for bundle delivery, the user removes it from the intermediate processing tray without performing bundle delivery. At this time, an intermediate processing tray overflow signal is used as a signal for starting display for prompting this on the image forming apparatus side. After step 147, an intermediate processing tray sheet presence signal is output to the image forming apparatus (S149) until the sheet is removed from the bundled paper discharge belt 421 (intermediate processing tray) (S148). While the intermediate tray overflow signal is received and the intermediate tray sheet presence signal is received, the image forming apparatus does not start the next image forming job.
[0038]
Further, when the variable N becomes 15 in step S144 and when the variable S becomes 60 or more in step S145, the intermediate processing tray overflow signal is sent to the image forming apparatus on the assumption that the intermediate processing tray has reached the limit load capacity. Is output (S150), and the process proceeds to step S148. Also at this time, the image forming apparatus displays so that the sheet on the intermediate processing tray is removed.
[0039]
When the process proceeds to step S129 and subsequent steps (in the case of a sheet other than the second original drawing), the aligning plate 412 is aligned according to the sheet size and the return roller 417 is rotated leftward. When the process proceeds to the above process (in the case of the second original sheet), the alignment plate 412 is retracted to a position where the sheet stacking is not hindered to perform the alignment operation, and the return roller 417 is not driven. FIG. 26 shows a state on the bundle discharge belt 421 when the second original sheet is discharged.
[0040]
FIG. 16 is a flowchart of the weighting count in steps S130 and S143. Based on the size information of each sheet received from the image forming apparatus, when the sheet length (length in the transport direction) is 297 mm or less (S151), 2 is added to the variable S (S152). When the sheet length is longer than 297 mm and less than 364 mm, 3 is added to the variable S (S154). When the sheet length is longer than 364 mm, 4 is added to the variable S (S155). By weighting the count value in accordance with the sheet length in this way, stacking up to the number of sheets suitable for bundle discharge is possible when performing bundle discharge, and intermediate when not performing bundle discharge. It is possible to stack the sheets so that the sheets are not scattered on the processing tray.
[0041]
FIG. 17 is a flowchart for controlling the stack tray 411 in the finisher 400. As shown in FIGS. 11 and 12, the finisher 400 is controlled so that the stack tray sheet height sensor S10 is turned on after the power is turned on. Then, after the sheets received from the image forming apparatus are bundled and discharged (S161), the stack tray 411 is lowered (S162), and whether or not the stack tray 411 has reached the lower limit is detected by the lower limit sensor S12 (see FIG. 10). Detect (S163). When the stack tray 411 does not reach the lower limit, that is, when the lower limit sensor S12 is not turned on, it is detected whether the height sensor S10 is turned off (see FIG. 18) (S164). When the height sensor S10 is not turned off, the process returns to step S162. When the height sensor S10 is turned off in step 164, the stack tray 411 is raised until the height sensor S10 is turned on (see FIG. 19) (S165, 166), and the height sensor S10 is turned on. After that, the stack tray 411 is continuously raised until it rises by a predetermined amount (S167, S168) and stopped (S169). The motor M5 that moves up and down the stack tray 411 is a direct current motor, and the finisher control unit 401 monitors the amount of lift of the stack tray 411 by inputting the number of pulses from an encoder provided on the shaft of the direct current motor. Can do.
[0042]
When the stack tray 411 reaches the lower limit in step S163, that is, when the lower limit sensor S12 is turned on, a stacker overflow signal is output to the image forming apparatus (S170), and the operation of the stack tray 411 is stopped (S171). Upon receiving this signal, the image forming apparatus displays “Please remove the paper on the stack tray” on its operation unit. Then, it is determined whether or not there is a job to be discharged next (S172), and if there is, a bundle is discharged continuously (S173). If there is no job to be discharged next, the printer waits until the height sensor S10 is turned off (S174), and when it is turned off, the stacker overflow signal is turned off (S175). In this way, when the lower limit is reached while the stack tray 411 is lowered, the jobs that have already been stopped at the time of detection of the lower limit without performing the ascending operation in steps S165 and S167 (for example, received from the computer 204). A bundle discharge process for several bundles corresponding to a job or the like is performed.
[0043]
Here, the position of the stack tray 411 suitable for bundle discharge will be described. If the distance from the bundle discharge belt 421 to the stacking surface on the stack tray 411 is too large, the stackability of the sheet bundle on the stack tray 411 is poor. Further, since the leading edge of the sheet while being discharged to the discharge roller 415 follows a trajectory as shown in FIG. 27, if the distance is too close, the sheet is placed on the inclined portion of the stack surface of the stack tray 411. The leading edge of the paper is abutted, and there is a possibility that a jam may occur during the conveyance of the paper discharge roller 415. Therefore, by the lowering and raising control in steps S162 to S169, the distance between the bundle discharge belt 421 and the stacking surface on the stack tray 411 is set to a distance that makes it difficult to jam and stackability is good.
[0044]
In this embodiment, since the upper surface of the sheet on the stack tray 411 is detected by the height sensor S10, if the upper surface of the sheet cannot be detected while the stack tray 411 is descending, the bundle discharge belt 421 and the stack tray 411 The exact distance from the loading surface cannot be controlled. Therefore, the thickness of the bundle may be controlled by estimating the number of sheets discharged from the bundle, but the thickness of the sheets varies, and the bundle thickness may not be as estimated. If a bundle that is thicker than estimated is discharged, the stack discharge belt 421 and the stacking surface of the stack tray 411 are close to each other as described above, and a jam may occur. For this reason, when the lower limit is reached while the stack tray 411 is being lowered, the stack bundle 411 is not raised by the control of steps S170 to S173, and the remaining bundle is discharged. As a result, the distance between the bundle discharge belt 421 and the stacking surface on the stack tray 411 may become slightly large, and the stackability on the stack tray 411 may be deteriorated. Since the sheet bundle discharged at this point is the last bundle, even if the stackability is somewhat poor, there is no significant effect.
[0045]
The finisher 400 has a slightly shorter bundle delivery belt 421 in order to provide a compact and low-cost finisher. When a long sheet such as A4R or A3 size is processed, a portion that does not fit on the bundle delivery belt 421 is supported on the stacker tray 411 (FIG. 28).
[0046]
When the image forming apparatus starts an image forming job in the staple mode, if the sensor S11 detects that sheets are stacked on the stack tray 411, the image forming apparatus displays “stack tray” Please remove the sheet from. "Is displayed. This is because when a stack of stapled sheets is stacked on the stack tray 411, the stapling portions overlap and the stackability is not very good. Therefore, it is desirable to start an image forming job with no sheets stacked on the stack tray 411 as much as possible. is there. However, since the image forming apparatus is used not only in the copying mode but also in the printer mode, considering that the user is not on the spot, even if the sheet is not removed, the image forming job (staple processing and bundle discharge processing is also performed). Including).
[0047]
Further, when the image forming apparatus completes 30 image forming jobs continuously in the staple mode, the image forming job is temporarily interrupted, and “Please remove the sheet from the stack tray” is displayed on the operation unit. Until the sheet is removed from the stack tray 411 and the sensor S11 is turned off, the image forming job is resumed.
[0048]
【The invention's effect】
As described above, according to the first aspect of the present invention, the stackable means for stacking discharged sheets and the upper surface of the sheets stacked on the stacking means are detected at a predetermined height. The first detection means, the elevating means for raising and lowering the stacking means, and detecting that the upper surface of the sheet is positioned at a predetermined height by the first detection means in response to the discharge of the sheet to the stacking means Control means for controlling the elevating means so as to lower the stacking means until it rises, and then raising the stacking means by a predetermined amount, and second detection means for detecting that the stacking means has reached the lower limit. While the stacking unit is being lowered, the lowering operation of the stacking unit is stopped in response to the second detecting unit detecting that the lower limit of the stacking unit has been reached before the first detecting unit detects the upper surface of the sheet. Do not raise the loading means When the lower limit is detected and there is a sheet to be discharged, the sheet is continuously stacked, so the distance between the sheet discharge position and the stacking surface of the stacking means is shorter than when the distance is longer than the optimum distance. In the case where time adversely affects the sheet, it is possible to prevent the sheet from being adversely affected as much as possible.
[0049]
According to the second aspect of the invention, it is possible to perform control suitable for discharging a bundle of sheets from the second stacking unit.
[0050]
According to the third aspect of the present invention, it is possible to prevent a jam from occurring when a large size sheet is discharged to the second stacking means.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating configurations of an image forming apparatus and a sheet processing apparatus.
FIG. 2 is a diagram for explaining the direction of document reading and image formation.
FIG. 3 is a block diagram of the image forming apparatus.
FIG. 4 is a block diagram of an image signal control unit.
FIG. 5 is a diagram illustrating a configuration of a finisher.
FIG. 6 is a diagram illustrating a sensor and a motor in the finisher.
FIG. 7 is a perspective view of a return roller and a bundle discharge belt.
FIG. 8 is a diagram illustrating a temporary stop position of a bundle discharge lever.
FIG. 9 is a diagram for explaining a driving mechanism for an alignment plate.
FIG. 10 is a diagram illustrating an elevating mechanism for a stack tray 411.
FIG. 11 is an operation timing chart of each unit when two copies of two originals are copied and offset discharge (without binding processing) is performed by the finisher.
FIG. 12 is an operation timing chart of each unit when two copies of two originals are copied and a binding process is performed by the finisher.
FIG. 13 is a flowchart of drive control of a paper discharge roller in the finisher.
FIG. 14 is a flowchart relating to the control of the intermediate processing tray in the finisher, particularly the bundle discharge control by the bundle discharge belt.
FIG. 15 is a diagram illustrating a screen for setting material in the image forming apparatus.
FIG. 16 is a flowchart of weighting counting.
FIG. 17 is a flowchart of stack tray control in the finisher.
FIG. 18 is a diagram illustrating a state of a height sensor.
FIG. 19 is a diagram illustrating a state of a height sensor.
FIG. 20 is a diagram illustrating a state of a sheet in the finisher.
FIG. 21 is a diagram illustrating a state of a sheet in the finisher.
FIG. 22 is a diagram illustrating a state of a sheet in the finisher.
FIG. 23 is a diagram illustrating a state of a sheet in the finisher.
FIG. 24 is a diagram illustrating a state of a sheet in the finisher.
FIG. 25 is a diagram illustrating a state of a sheet in the finisher.
FIG. 26 is a diagram illustrating a state of a sheet in the finisher.
FIG. 27 is a diagram illustrating a state of a sheet in the finisher.
FIG. 28 is a diagram illustrating a state of a sheet in the finisher.
[Explanation of symbols]
400 finisher
411 Stack tray
412 Alignment plate
415 Paper discharge roller
417 Return roller
419 Staple unit
420 Paper holding lever
421 Bundle output belt
421A Bundle output lever
421B Intermediate processing tray loading auxiliary plate

Claims (3)

A stacking means capable of moving up and down to stack discharged sheets;
First detecting means for detecting that the upper surface of the sheets stacked on the stacking means is positioned at a predetermined height;
Elevating means for elevating and lowering the loading means;
In response to the discharge of the sheet to the stacking unit, the stacking unit is lowered until the first detecting unit detects that the upper surface of the sheet is positioned at a predetermined height, and then the stacking unit is placed. Control means for controlling the elevating means to raise the fixed amount;
Second detection means for detecting that the loading means has reached a lower limit;
Have
In response to detecting that the lower limit of the stacking unit has been reached by the second detection unit before the first detection unit detects the upper surface of the sheet while the stacking unit is being lowered, Controlling the elevating means to stop the lowering operation of the loading means and not to raise the loading means;
A sheet stacking apparatus that continuously stacks sheets when there is a sheet to be discharged at a lower limit detection time.   A second stacking unit provided on the upstream side of the stacking unit for stacking sheets; and a bundle discharging unit for discharging the sheets stacked on the second stacking unit onto the stacking unit in a bundle state. The sheet stacking apparatus according to claim 1, further comprising:   The position of the stacking means raised by a predetermined amount after the detection by the first detection means is a position that is not obstructed by the stacking surface of the stacking means when discharging the large size sheet to the second stacking means. The sheet stacking apparatus according to claim 2, wherein the sheet stacking apparatus is provided.

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