JPH09235066A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To use sheets equivalent to the number of classification as a mark of a group of the sheets required to be classified by differring a rear end position of the sheets equivalent to the number of classification against the group of the sheets required to be classified from a rear end position of other loaded sheets. SOLUTION: End plates 11, 12 are set doubly along the discharge direction of paper, the end plate 12 positioned on the upstream side in the discharge direction of paper is made free to elevate, it is lowered at the time when paper equivalent to the number of classification is discharged, and paper equivalent to the number of classification is loaded in a state where it is slipped by the amount of thickness of the end plate 12 against other loaded paper.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus, and more particularly to a sheet sorting apparatus used in the apparatus.

[0002]

2. Description of the Related Art Conventionally, there is a printing apparatus as one of image forming apparatuses for transferring the contents corresponding to an original image onto a sheet, and the printing apparatus includes a stencil printing apparatus and an offset printing apparatus. The case where an image is formed by using a stencil printing apparatus among printing apparatuses will be described below. The stencil printing machine is adapted to wind a stencil master punched in accordance with an original image by a punching process corresponding to a plate making process, around a plate cylinder provided with an ink permeable structure. The stencil master is soaked with ink from an ink supply mechanism installed in the plate cylinder and transferred to a printing paper pressed against the plate cylinder to transfer an image, thereby performing printing. The stencil printing apparatus has an advantage that economical image transfer can be performed because printing can be performed only by using one type of stencil master when a large amount of printing is continuously performed.

In the image forming apparatus including the above-mentioned stencil printing apparatus, in the case of printing, for example, printed printing paper may be sorted into arbitrary number of sheets. For this reason, a mechanism for sorting the desired number of print sheets is provided in the print sheet discharge section (for example, Japanese Patent Laid-Open No. 7-1722 and Japanese Patent Publication No. 6-78151). The former publication discloses a configuration in which a tape on which sorting information is recorded is delivered to the surface of a printing sheet that has reached the number of sorting sheets, and the tape is sandwiched between printing sheets to be sorted next.

The latter publication discloses a configuration in which the direction of the print paper discharge direction along the print paper discharge direction is switched by 90 ° for each number of sorted sheets.

[0005]

However, the structure described in the above publication has the following problems. In the configuration described in the former publication, it is necessary to prepare a dedicated tape for sorting. This means that not only the structure for feeding the tape and the structure for recording the sorting information have to be added to the structure of the printing apparatus itself, but also a part called a tape that is not related to printing is required. High costs will be incurred. Moreover, since the shape of the tape is relatively thin and long, the behavior when falling toward the upper surface of the printing paper is difficult to stabilize, and the sorting information is recorded and then immediately drops onto the upper surface of the printing paper. Not not.
For this reason, it is impossible to position the tape at a predetermined position by operating the tape toward the position where the tape should be sandwiched, because the timing of the ejecting operation of the printing paper does not match the drop of the tape. In addition, when the print sheets stacked on the paper output section are taken out, the tape sandwiched between the print sheets may fall off or be damaged. It

In the structure described in the latter publication, the structure of the paper discharge tray becomes large-scaled, which causes an increase in cost. Further, since the direction of the print sheets to be stacked is switched depending on the number of sheets to be sorted, the increase in the stacking amount increases the driving force and time required for the direction switching due to the increase in the weight, which makes the structure unsuitable for high-speed printing. Moreover, since the function as a side fence is performed by the four shafts corresponding to the four corners of the paper, the edges of the printing papers cannot be aligned sufficiently, and the edges of the printing papers sorted and stacked are not uniform. It will be in a state.

SUMMARY OF THE INVENTION In view of the problems of the above-mentioned conventional image forming apparatus, especially the sheet sorting mechanism used in the apparatus, an object of the present invention is to reliably sort sheets by adding a little structure to the existing sheet discharge configuration. An object is to provide an image forming apparatus provided with a sorting device.

Another object of the present invention is to provide an image forming apparatus equipped with a sheet sorting apparatus capable of aligning the edges of stacked sheets and setting the sorting system without complicating the structure relating to sorting. To provide a device.

[0009]

In order to achieve this object, the invention according to claim 1 is an image forming apparatus equipped with a sheet discharge tray on which sheets discharged after image formation can be stacked.
The elevating end, which is arranged on the paper ejection table in a direction perpendicular to the paper ejecting direction, includes a fixed end plate and an elevating end plate that stop the front edge of the paper, and is capable of elevating along the fixed end plate. It is characterized in that the plate is provided with a paper sorting device arranged upstream of the fixed end plate in the paper discharge direction.

According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, the elevating end plate descends according to the number of sorting sheets, and a sheet for stopping the front end of the ejected sheet is stopped. It is characterized by having a sorting device.

According to a third aspect of the present invention, when the elevating end plate descends, a sheet sorting device is provided which stops the descending operation when it comes into contact with the upper surface of the sheet stacked on the sheet discharge tray. It has a feature.

According to a fourth aspect of the present invention, in the image forming apparatus according to the first aspect, the elevating end plate and the fixed end plate are separate members, and the elevating end plate is connectable to the fixed end plate. It is characterized in that it is equipped with a sheet sorting device provided in.

According to a fifth aspect of the present invention, in the image forming apparatus according to the first aspect, the sheet sorting apparatus is configured such that the elevating end plate is expandable and contractable, and a driving unit for elevating the elevating end plate. A first elevating end plate portion which is partly connected to the driving means and can be interlocked, a second elevating end plate portion movably supported with respect to the first elevating end plate portion, An elevating position detecting means provided on each of the first and second elevating end plate portions and detecting an elevating position of the second elevating end plate portion, wherein the driving means is provided with a signal from the elevating position detecting means. It is characterized by being drive-controlled.

According to a sixth aspect of the present invention, in the image forming apparatus according to the fifth aspect, the second elevating end plate portion is provided with pressing means for pressing a sheet whose front end is stopped by the elevating end plate. It is characterized by being provided.

According to a seventh aspect of the present invention, in the image forming apparatus according to the sixth aspect, the pressing means is normally provided with a habit of retreating from the sheet, and the first elevating end plate portion is lowered. It is characterized in that it is composed of a pressing member which can be brought out toward the surface of the above-mentioned paper in interlocking manner.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described below with reference to the embodiments shown in the drawings.

FIG. 1 is a perspective view showing the structure of a paper discharge tray in the image forming apparatus according to the present invention. In FIG. 1, the paper output tray 10 has a fixed end plate 11 and a lifting end plate 12 at a position facing the front end of the print paper to be discharged.
A sheet sorting device 13 including the above is arranged. In FIG. 1, reference numeral 100 indicates a printing device, and printing paper is ejected from the printing device 100 in the direction of the arrow in the figure. Further, in the figure, reference numeral 101 indicates a side fence for aligning the widthwise end edges of the paper, and the side fence 101 can be moved in the width direction by a sliding mechanism (not shown). Is positioned at a position corresponding to the size of.

The sheet sorting device 13 is a device used to sort a plurality of printing sheets into a predetermined number of sheets, and the fixed end plate 11 is installed on the delivery tray 10 although the details are not shown. For example, a sliding mechanism as shown in the specification of Japanese Patent Application No. 8-19800 filed by the applicant of the present application (only a part of the mechanism is shown by reference numeral 11A in the drawings for convenience. It is possible to move along the paper discharge direction via the (. The fixed end plate 11 is positioned at a position corresponding to the length of the paper in the paper ejection direction.

The fixed end plate 11 is integrally provided with a housing 14A for accommodating the drive means 14 (see FIG. 2) for the elevating end plate 12, which is connected by screws or the like. The means 14 can be linked to the movement of the fixed end plate 11.
Therefore, an image forming apparatus having a sheet sorting function can be easily provided by adding a lifting end plate 12 of the present invention described later to the conventional fixed end plate 11. Although the fixed end plate 11 and the elevating end plate 12 are separate members as described above in the present embodiment, the elevating end plate 12 is described.
Of course, the role of the fixed end plate 11 may be given to the portion of the housing 14A housing the driving means 14 of FIG.

FIG. 2 is a schematic perspective view showing the arrangement of members constituting the elevating end plate 12. In FIG. 2, the drive means 14 is driven via a drive motor 15 provided in the housing 14A and capable of rotating in the forward and reverse directions, a drive pulley 15A provided on the output shaft of the drive motor 15, and a belt 16. A driven pulley 17 interlocking with the pulley 15A,
A threaded rod 18 that forms a rotation axis of the driven pulley 17 and has a thread formed on the circumferential surface, and an elevating block 19 that meshes with the threaded rod 18 and is movable in the vertical direction parallel to the axial direction of the threaded rod 18 according to the rotation direction of the threaded rod 18. And a lifting rod 20 whose one end in the axial direction is fixed to the lifting block 19.

The elevating end plate 12 is arranged upstream of the fixed end plate 11 in the paper discharge direction (the direction shown by the arrow in FIG. 1), and the first elevating end plate portion 12A and the second elevating end plate 12 are provided. Lifting end plate part 12B
And First lifting end plate portion 12A
Is coupled to the other end of the elevating rod 20 in the axial direction and has a space in which the second elevating end plate portion 12B is inserted.

The second elevating end plate portion 12B is suspended and supported so as to be able to ascend and descend with respect to the first elevating end plate portion 12A through the slide mechanism including the stepped screw 34 and the elongated hole 35 shown in FIG. It can be interlocked with the lowering of the first elevating end plate portion 12A. When the second elevating end plate portion 12B descends in conjunction with the first elevating end plate portion 12A, the second elevating end plate portion 12B comes into contact with the upper surface of the stacked sheets. Since the second elevating end plate portion 12B cannot be further lowered, it is inserted into the first elevating end plate portion 12A as the first elevating end plate portion 12A descends. In this way, the second elevating end plate portion 12B is displaced in the direction in which the second elevating end plate portion 12B is inserted into the first end plate portion 12A and in the direction opposite thereto, so that the elevating end plate 12 can expand and contract.

The second lifting end plate portion 12B includes
A rotary shaft 21 is provided, and the base end of a paper pressing arm 22 which is a pressing member forming pressing means for pressing the paper is fixed to the rotary shaft 21.

The paper pressing arm 22 is a member that can be swung about the rotary shaft 21 as a fulcrum, and an arm driving member 23 is attached to the swing end side.

The arm driving member 23 is used for the paper pressing arm 2.
The rod member 24 is connected to the swinging end of the rod member 24, and the drive lever 25 is connected to the axial end of the rod member 24 at one end in the extension direction. Drive lever 25
The other end in the extension direction is the first lifting end plate portion 12
Located in A. Second lifting end plate portion 12
When B is inserted into the first elevating end plate portion 12A, the protrusion 3 provided on the first elevating end plate portion 12A.
Since the drive lever 25 is pushed and moved by hitting the drive lever 25 against 2, the swing end of the paper pressing arm 22 can be swung.

The paper pressing arm 22 includes a projection 32 and a drive lever 25 which are provided on the first end plate 12A side.
It can be brought out to the sheet stacking surface side by hitting and, and is normally kept in a state not to be brought out to the sheet stacking surface by a biasing means such as a spring 33.

In order to expose the paper pressing arm 22 to the paper stacking surface, the drive lever 25, as shown in FIG. 3, is located closer to the paper stacking surface than the vertical line passing through the center of the rotary shaft 21. The connecting portion is connected to the swinging end 22 and, in a normal state, the connecting portion is positioned at a position shifted in the clockwise direction in FIG. 3 from the vertical line. As a result, when the drive lever 25 is pushed and moved by the protrusion 32 located on the side of the first elevating end plate portion 12A,
The sheet pressing arm 22 swings toward the sheet placement surface side due to the rotation moment.

The first and second lifting end plate portions 12
A and 12B are provided with a configuration as an elevation position detecting means for detecting the elevation position of the second elevation end plate portion 12B. In FIG. 2, the second lifting end plate portion 12B is provided with a sensor detection plate 26 extending in the lifting direction, and the first lifting end plate portion 1 is provided.
2A includes first and second position detection sensors 27, 2 formed of transmissive optical sensors in the hoistway of the sensor detection plate 26 along the hoisting direction of the second hoisting end plate portion 12B.
8 are arranged.

The first position detecting sensor 27 detects that the second elevating end plate portion 12B has come into contact with the upper surface of the sheets stacked on the sheet discharging tray 10, and has a driving motor provided in the driving means 14. The second position detection sensor 28 is provided for outputting a signal for temporarily stopping the first and second drive end plates 15 when the drive motor 15 in the temporarily stopped state is driven again. The lower limit position of the lowering operation of the 12A is regulated, and the swing amount of the paper pressing arm 22 is regulated.

The first and second position detecting sensors 27,
The output signal from 28 is input to the control unit 29 shown in FIG. Although not shown in detail, the control unit 29 is provided with a microcomputer as a main part, and controls the rotation of the drive motor 15 of the drive unit 14. Thus, in this embodiment, the first elevating end plate portion 12A and the second elevating end plate portion 12B constitute the elevating end plate 12, and the first position detecting sensor 27 forms the second elevating end plate portion. Part 12B is output tray 1
Since it is possible to detect that the upper surface of the paper stacked on 0 is detected, even if the position of the stacked paper changes when sorting is performed, the lifting end is corresponding to the change in the position. The plate 12 can be moved up and down. It should be noted that, as in the present embodiment, a two-piece lift end plate 1 having first and second lift end plate portions.
Even in the case of a single-body lifting end plate 12 'instead of 2, a micro switch or the like having a swinging piece so as to output a detection signal when completely contacting the upper surface of the paper stacked on the lower end portion Needless to say, if they are arranged, the lifting end plate 12 ′ can be similarly moved up and down.

In FIG. 4, the control unit 29 has the above-mentioned first and second terminals on the input side via an interface (not shown).
The second position detection sensors 27 and 28, the operation panel 30, and the paper discharge sensor 31 are connected, and the motor drive unit 15B of the drive motor 15 is connected to the output side.

The operation panel 30 (not shown) of the printing apparatus 100 (see FIG. 1) is equipped with an operation unit for inputting the number of printed sheets and the number of sorted sheets. It can be entered as a number. Further, the paper discharge sensor 31 (not shown) is
A transmissive or reflective optical sensor that is a member that detects the passage of paper discharged from the printing device toward the paper output tray 10 (see FIG. 1), and is installed in the discharge port (not shown) of the printing device 100. Is used.

The control unit 29 controls the rotation of the drive motor 15 for raising and lowering the raising and lowering end plate 12 located on the sheet discharge tray 10 according to the number of sheets sorted from the operation panel 30. . When the content related to the sorting process is input from the operation panel 30, the control unit 29 stores the number of sorted sheets, and determines the actual number of discharged sheets corresponding to the number of sheets by the output signal from the sheet discharge sensor 31. When the number of discharged sheets counted by the sheet discharge sensor 31 corresponds to the value of the number of sorted sheets, the position for lowering the elevating end plate 12 is set at the timing when the sheets are introduced onto the sheet discharge tray 10. .

When the second elevating end plate 12B comes into contact with the upper surface of the stacked sheets as the second elevating end plate 12B descends, the second elevating end plate 12B does not descend further and the first Only the ascending / descending end plate portion 12A of FIG.

When the second elevating end plate portion 12B is fitted into the first elevating end plate portion 12A by lowering the first elevating end plate portion 12A, the first and second elevating end plate portions 12A and 12B are relatively displaced, and the sensor detection plate 26 located on the second elevating end plate portion 12B side faces the first position detecting sensor 27 located on the first elevating end plate portion 12A side. , The detection signal from the first position detection sensor 27 is the control unit 2
9 is output.

In the controller 29, the first position detecting sensor 2
The drive motor 15 is once stopped based on the detection signal from 7. As a result, the elevating end plate 12 can stop the front end of the ejected paper, and the thickness of the elevating end plate 12 in the ejecting direction of the paper causes the trailing end side (upstream side) of the other stacked sheets in the ejecting direction. It is possible to shift the trailing edge position of the sheet corresponding to the value of the number of sorted sheets compared to the position.

The control unit 29 maintains the state where the rotation of the drive motor 15 is stopped for a predetermined time. The predetermined time in this case corresponds to the time until the front end in the discharge direction of the paper discharged onto the paper discharge tray 10 is stopped by the elevating end plate 12.

When the rotation stop of the drive motor 15 is maintained for a predetermined time, the control unit 29 again rotates the drive motor 15 in the direction of lowering the first end plate portion 12A of the elevating end plate 12. When the drive motor 15 is restarted, only the first elevating end plate portion 12A descends, so this time the first elevating end plate portion 12A.
The second position detection sensor 28 and the second
The sensor detection plate 26 in the elevating end plate portion 12B comes to face.

In the control unit 29, the second position detecting sensor 2
Drive motor 1 until the detection signal from 8 is output.
Maintain 5 rotations. As a result, the first elevating end plate portion 12A descends, so that the drive lever 25 is pushed and moved by the protrusion 32 installed in the first elevating end plate portion 12A.

When the drive lever 25 is pushed and moved, the paper pressing arm 22 is swung toward the paper stacking surface side via the arm driving member 23 including the drive lever 25, and the front end is stopped by the elevating end plate 12. It is possible to place the swinging end of the paper pressing arm 22 on the existing paper and press the paper for sorting whose position on the rear end side in the discharge direction is displaced. Further, in this embodiment, the case where only one sheet for sorting is shifted and stacked is explained, but, for example, when it is desired to sort the whole printing sheet into two blocks (lumps), By the way, lower the lifting end plate 12 and leave it as it is.
Of course, it is also possible to sort the blocks into two blocks by stacking subsequent printing sheets. In this case, the elevating end plate 12 does not require any pressing means for pressing the sheets, and may be a single-piece elevating end plate having a function of detecting the height of the upper surface of the stacked sheets. Further, if the one-body lifting end plate 12 'is not made compact or the like, it is easily conceivable to provide a plurality of the lifting end plates 12' so that they can be sorted into a plurality of blocks.

Since this embodiment has the above-mentioned configuration,
The operation procedure will be described below with reference to the flowchart shown in FIG. The flowchart shown in FIG.
It shows a case where 10 blocks of 50 print sheets are created. On the operation panel 30, the number of prints and the number of blocks (the number of copies) are input as a set number. In this case, for example, the numeric keypad is used to input "50 × 10" (step S1). In FIG. 5, only the step number is entered, and the word “step” is not used. In the printing apparatus 100, the plate making process is executed, and a master having an image to be printed with the above-mentioned number of copies is created (step S2).

The printing process is executed by the master which has been prepressed (step S3), and the number of sheets discharged after printing is counted by the sheet discharge sensor 31 (see FIG. 4). It is determined whether or not the count value based on the output signal of the paper discharge sensor 31 corresponds to the value immediately before the number of sorted sheets (step S4). In this case, it is determined whether the count value is 49.

As shown in FIG. 6A, the elevating end plate 12 rises to face the front end in the paper discharge direction until the count value of the paper discharge sensor 31 reaches a value just before the number of sorted sheets. It is supposed not to. Therefore, the ejected sheets are aligned with the front end in the ejection direction being stopped by the fixed end plate 11.

In step S4, when the value corresponds to the value just before the number of sorted sheets, printing is stopped (step S5), and the drive motor 15 of the driving means 14 starts forward rotation (step S6). ).

The forward rotation in this case corresponds to the direction in which the elevating end plate 12 can descend. Drive motor 15
Continues to rotate in the normal direction, the elevating end plate 12 descends (step S7), the second elevating end plate portion 12B contacts the upper surface of the stacked sheets, and the second elevating end plate portion 1
2B enters into the first elevating end plate portion 12A, and only the first elevating end plate portion 12A descends.

However, the control unit 29 determines whether or not there is a signal from the first position detection sensor 27 (step S
8) Then, the drive motor 15 is stopped when the signal is input (step S9).

At this point, as shown in FIG. 6B, the elevating end plate 12 is set in a state in which it is possible to stop the leading end of the sheets in the discharge direction in the order corresponding to the number of sorted sheets to be discharged next.

When the drive motor 15 is stopped, the control unit 2
In 9, the time corresponding to the moving time until the next sheet to be discharged reaches the elevating end plate 12 on the sheet discharge tray 10 is measured (step S10). This time counting time is the time required for printing on the sheets in the order corresponding to the number of sheets to be sorted (step S11), and the transportation time until the sheets reach the elevating end plate 12 on the sheet discharge tray 10 after printing. It is made to correspond. As a result, when the sheets in the order corresponding to the number of sorted sheets are discharged onto the sheet discharge tray 10, the sheets are stacked up to the position on the rear end side in the discharging direction as shown in FIG. 6B. The sheets are stacked in a state of being displaced by the thickness of the lifting end plate 12 from the rear end position of the sheets.

It is judged whether or not the time counting started in step S10 has reached a predetermined time (step S12),
When it is determined that the predetermined time has elapsed, the drive motor 15
Is again rotated normally (step S13).

When the drive motor 15 rotates in the normal direction again, only the first elevating end plate portion 12A descends because the second elevating end plate portion 12B is in contact with the sheet (step S14).

When only the first raising / lowering end plate portion 12A is lowered, the protrusion 32 provided in the first raising / lowering end plate portion 12A pushes the drive lever 25 located in the second raising / lowering end plate portion 12B to move the paper. The pressing arm 22 is swung clockwise in FIG. 6C to press the paper whose front end in the discharge direction is stopped by the elevating end plate 12, that is, the paper in the order corresponding to the number of sorted sheets (step S15, 16).

The larger the swing amount of the paper pressing arm 22 is, the larger the descending amount of the first elevating end plate portion 12A is. The descending amount is the second position detecting sensor 28 and the sensor detecting plate. It is determined based on the correspondence relationship with 26 (step S17).

When the detection signal from the second position detection sensor 28 is input to the control unit 29, the control unit 29 stops the drive motor 15 (step S18). As a result, the sheets discharged in the order corresponding to the value of the number of sorted sheets are in a state in which the front end in the discharge direction is stopped by the elevating end plate 12 and can be distinguished from the sheets which do not correspond to the number of sorted sheets. The paper pressing arm 22 presses the vicinity of the front end of the paper in the sheet ejection direction and pushes out the air layer on the back surface of the paper (between the papers). The occurrence of unstable behavior such as slipping off is prevented. Further, when the next sheet is stacked, the deviation due to the external force from the sheet hardly occurs.

After the paper pressing arm 22 of the second elevating end plate portion 12B executes the paper pressing operation, the drive motor 15 is rotated in the reverse direction (step S19).

When the drive motor 15 rotates in the reverse direction, the first elevating end plate 12A rises, and the second end plate portion 12B suspended and supported by the first elevating end plate 12A also rises, and the elevating end plate 12 corresponds to the number of sorted sheets. The sheets are discharged in order (step S20). In this case, as for the amount of increase, the correspondence relationship between the second position detection sensor 28 and the sensor detection plate 26 is canceled, and thereafter, the correspondence relationship between the first position detection sensor 27 and the sensor detection plate 26 is canceled. After the above sequence, the amount is a period from when a predetermined time elapses to when the reverse rotation of the drive motor 15 is stopped. As a result, the lifting end plate 12
Among the sheets to be discharged next, the sheets can be waited in a state in which the sheets to be discharged in the order corresponding to the number of sorted sheets can be lowered for shifting.

When the elevating end plate 12 is raised, printing is started according to the number of sorted sheets corresponding to the next number of copies (step S21). As shown in FIG. 6D, the paper discharged after the sorting group in the former stage by the printing executed in step S21 is the fixed end plate 1 as shown in FIG.
1, the front end in the discharging direction is stopped. As a result, the sheets discharged in the order corresponding to the number of sorted sheets and the other sheets have different trailing end positions in the discharge direction, so that the sorted sheet group can be easily identified.

It is determined whether or not the number of times of shifting the discharged sheets in the order corresponding to the number of sorted sheets corresponds to the number of sheets registered in step S1 (step S2).
2) The process is continued until the numbers match, and when they match, the printing and sorting work is ended.

In the above flow chart, up to 49 sheets are continuously printed corresponding to the number of 50 sheets to be sorted, and the trailing edge position of the sheet corresponding to the 50th sheet is displaced from the trailing edge positions of other sheets. However, if the number of sheets to be sorted is 50, for example,
The rear end position in the ejection direction may be shifted with respect to the rear end position of the subsequently ejected papers for the first paper of the next paper group to be sorted.

[0059]

As is apparent from the above description, according to the first to third aspects of the present invention, the rear end position of the sheets corresponding to the number of sheets to be sorted is loaded to another stack for the sheet group requiring sorting. Since the position of the rear end of the sheet can be different from that of the trailing edge of the sheet, the sheet corresponding to the number of sheets to be sorted can be used as a mark of a sheet group that requires sorting. Further, according to the invention as set forth in claim 4, by simply adding an elevating end plate capable of ascending and descending to a fixed end plate provided for stopping the front end of the sheet in the discharge direction, another type of tape or the like is added. Sorting can be made possible without requiring parts.

According to the invention of claim 5, in addition to the effects of the inventions of claims 1 to 4, even if the position of the stacked sheets changes, the drive means is driven in response to the change of the position. Since the sorting position can be set by the control, it is possible to surely perform the shifting operation of the sheets to be sorted regardless of the amount of the stacked sheets.

According to the sixth and seventh aspects of the present invention, after the sheet whose front end in the ejection direction is stopped by the elevating end plate is struck against the elevating end plate and stacked, the elevating end plate is formed by the air layer interposed on the back surface of the sheet. It is possible to prevent the paper from slipping off when the paper is raised by using the pressing means, and also to prevent the paper from being displaced by the next stacked paper. Therefore, it is possible to surely distinguish the sheets at the positions corresponding to the number of sorted sheets as the marks for sorting.

[Brief description of drawings]

FIG. 1 is a perspective view showing an installed state of a sheet sorting apparatus used in an image forming apparatus according to the present invention.

FIG. 2 is a schematic perspective view for explaining a main part configuration of the paper sorting apparatus shown in FIG.

FIG. 3 is a view in the direction of the arrow L3 in FIG.

FIG. 4 is a block diagram for explaining the configuration of a control unit used in the paper sorting apparatus shown in FIG.

5 is a flowchart for explaining an operation procedure of a sheet sorting apparatus using the control unit shown in FIG.

FIG. 6 is a schematic diagram for explaining the operation of the sheet sorting apparatus shown in FIG. 2, in which (A) shows a state before sorting,
(B) and (C) show the sorting state, and (D) shows the state after sorting.

FIG. 7 is a schematic view of a slide mechanism of a first lifting end plate portion and a lifting end plate portion of a base.

[Explanation of symbols]

10 Paper Discharging Table 11 Fixed End Plate 12 Lifting End Plate 12A First Lifting End Plate Part 12B Second Lifting End Plate Part 13 Paper Sorting Device 14 Drive Means 15 Drive Motor 22 Paper Press Arm 23 Arm Drive Member 25 Drive Lever 26 Sensor detection plate 27 Position detection sensor forming first elevating position detecting means 28 Position detection sensor forming second elevating position detecting means 29 Control unit 30 Operation panel 31 Paper ejection sensor 32 Protrusion 33 Spring

Claims (7)

[Claims] 1. An image forming apparatus provided with a paper discharge tray on which paper discharged after image formation can be stacked, the front edge of the paper being arranged on the paper discharge tray at a right angle to the paper discharge direction. A sheet sorter having a fixed end plate and a lift end plate for stopping the sheet, and the lift end plate capable of moving up and down along the fixed end plate is arranged upstream of the fixed end plate in the paper discharge direction. An image forming apparatus characterized by the above. 2. The image forming apparatus according to claim 1, wherein the elevating end plate includes a sheet sorting device that descends in correspondence with the number of sorting sheets and stops the front end of the discharged sheets. An image forming apparatus characterized by. 3. An image forming apparatus according to claim 1, wherein when the elevating end plate is descending, the descending operation is stopped when it comes into contact with the upper surface of the sheets stacked on the sheet ejection tray. An image forming apparatus comprising a device. 4. An image forming apparatus according to claim 1, wherein the lifting end plate and the fixed end plate are separate members, and the lifting end plate is provided so as to be connectable to the fixed end plate. An image forming apparatus comprising a sorting device. 5. The image forming apparatus according to claim 1, wherein in the paper sorting device, the elevating end plate is extendable and contractable, and a driving means for raising and lowering the elevating end plate and one of the driving means. A first elevating end plate portion that is linked and interlockable with each other, a second elevating end plate portion that is supported so as to be able to elevate and lower with respect to the first elevating end plate portion, and the first and second An elevating position detecting means provided on each elevating end plate portion for detecting an elevating position of a second elevating end plate portion, and the drive means is driven and controlled by a signal from the elevating position detecting means. A characteristic image forming apparatus. 6. The image forming apparatus according to claim 5, wherein the second elevating end plate portion is provided with pressing means for pressing the sheet whose front end is stopped by the elevating end plate. A characteristic image forming apparatus. 7. The image forming apparatus according to claim 6, wherein the pressing means is normally provided with a habit of retreating from the paper, and the paper is moved in association with the lowering operation of the first elevating end plate portion. An image forming apparatus comprising a pressing member that can be exposed to the surface.