JPH02305755A - Sheet transfer device - Google Patents

Abstract

PURPOSE:To put a sheet on a middle tray stably by setting the position of a carriage roller for discharging the sheet to the middle tray to be the same position regardless of the size of the sheet to be discharged so as to eliminate rounding phenomenon of the discharged sheet by reduction of the strength or curling at the forward end of the sheet when it is discharged. CONSTITUTION:When a sheet S of a small size is discharged onto a middle tray 183, a carriage unit 2 where the sheet S is delivered discharges the sheet S at a predetermined position (position of a sensor 47). For discharging the sheet of a large size onto the middle tray 183, the carriage unit 2 where the sheet S is delivered discharges the sheet S at the predetermined position (position of the sensor 47). The discharge position of the sheet S by the carriage unit 2 is the same position regardless of the size of the sheet S, thereby the sheet S can be put on the middle tray 183 stably without being affected by the strength of the sheet S or curling at the forward end of the sheet S.

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Field of Industrial Application The present invention relates to a sheet storage device, and more particularly, to a transport bus for a duplex unit installed in an image forming apparatus such as a copying machine.

(B) Conventional technology Conventionally, as a recording device such as a copying machine or a printer, there has been an automatic duplex copying machine using an electrostatic recording method, and the configuration of the apparatus that performs automatic duplexing of this copying machine can be broadly classified into two types. be done.

The first automatic duplex configuration is the copy 11 page shown in Figure 30.
The basic configuration is an S-shaped bus located at *. In the figure, an original is placed on a platen 152 disposed at the top of a copying machine main body 151 of a copying machine P2, and the original is scanned by an optical system 156 in the copying machine main body 151 to an image forming section 157. A latent image is formed by exposing the photosensitive drum. By developing this latent image, a toner image is formed in the image forming section 157. The copying machine main body 151 is provided with a plurality of cassettes 159, 160 for storing sheets S, a manual feed cassette 161, etc., and a cabinet 162 in which the copying machine main body 151 is placed. A large number of sheets S are also stored in the section 163. These sheets S are fed by a paper feeding section 165 including rollers, separation rollers, etc. provided in each cassette.

The sheet S fed by a paper feeding unit such as the paper feeding unit 165 has a toner image transferred thereto at the transfer unit 166 of the image forming unit 157, and is then transferred to the fixing unit 1 by the conveyor belt 167.
After the toner image on the sheet S conveyed to the sheet 69 is fixed by heating and pressurizing, the sheet S is discharged onto a discharge tray 172 from a paper discharge section 171 consisting of a pair of paper discharge rollers 170.

Here, when performing double-sided copying in which images are formed on both the front and back sides of one sheet S, or multiple copying in which images are formed by overlapping two or more original images on one side of one sheet S,
The sheet S on which the toner image is formed on the first surface is not discharged outside the machine, but is guided to the branch bus 175 via the flapper 173. First, in the case of double-sided copying, sheet S is 8 character bus 17
6, the paper is discharged onto the intermediate tray 179 by the final discharge roller pair 177. Further, during multiple copying, the paper is discharged from the middle of the eight-character bus 176 onto the intermediate tray 179 via the deflecting members 180 and 181 located halfway along the eight-character bus 176. Sheets S stacked on intermediate tray 179
The image is separated from the lower side and fed, and after passing through the paper refeed bus 182, the image is transferred again at the transfer unit 166 for double-sided copying or multiple copying.

The second automatic double-sided configuration is the copying machine P3 shown in FIG.
The basic configuration is a C-shaped bus located in the center.

In the same figure, when performing double-sided/multiple copying, the device with the C-shaped bus configuration forms an image on the first side, similar to the device with the basic configuration of the S-shaped bus described above. The sheet S is transferred to a branch bus 175 via a flapper 173.
be led to.

During double-sided copying, it is necessary to stack the sheets S on the intermediate tray (sheet storage means) 183 with the image surface obtained by the first transfer facing north.
The paper is once transported to the switchback bus 186 via the switchback bus 186, where it is switched back and then sent to the transport section 187 above the intermediate tray 183. Then, the sheet S is transferred to the conveying section 18
7 predetermined deflection members 189, 190 or the most distal discharge roller 191 onto the conveying section 183. At the time of multiple copying, the sheet S is directly discharged onto the intermediate tray 183 from a predetermined position of the conveying section 187 without sending the sheet S from the flapper 185 to the switchback path 186.

In order to provide an appropriate ejection position depending on the size (length) of the sheet S for both double-sided copying and multiple copying, a deflection plate 189 that allows the ejection position to be switched to multiple locations;
190 is arranged above the intermediate tray 183.

(c) Problems to be solved by the invention However, the copy Pa constituting the above-mentioned S-shaped bus
In the case of p t, the conveyance path of the sheet S from the fixing unit 169 to the paper refeed bus 182 becomes very long, and therefore...
There is a drawback that the size of the copying machine P2, especially its height, becomes very large.

Furthermore, due to the long conveyance path, there is a problem in that when a jam occurs, there are many locations where jam removal is to be performed, making the jam removal operation time-consuming.

Furthermore, during double-sided copying, the sheet S discharged to the intermediate tray 179 was aligned in the sheet feeding direction by expecting some movement effect from the inclined surface of the intermediate tray 179 and the sheet S's own weight. S to middle tray 17
A loss time occurs after the paper is ejected to 9 and before entering the paper refeeding process. This problem becomes more pronounced as the number of double-sided copies of the sheet S is reduced, and there is a drawback that the productivity of the copying machine P3 is reduced particularly when making a single double-sided copy.

In addition, in the case of a copying machine P3 that enables double-sided copying using a C-shaped bus, when discharging a large size (A3, 84, etc.) sheet S to the intermediate tray 179, the discharge position of the sheet S is inevitably tends to move away from the leading edge stopper position when refeeding. For this reason, due to the stiffness of the ejected sheet S or the curling of the leading edge of the sheet S, the stiffness of the sheet S may be broken or the leading edge may be curled during sheet ejection, causing the sheet S to be stacked on the intermediate tray 183. It contained extremely unstable factors in terms of gender.

Moreover, above the intermediate tray 183, small size (
A4. Deflection plate 189 for discharge bus compatible with BS etc.
, 190, etc. are protruding, due to the equipment configuration, the gap between the ejection bus and the intermediate tray 183 is such that if a transport failure occurs on the ejection bus or within the intermediate tray 1/183, the paper jam will be removed. There was a problem that sex became significantly worse.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a sheet conveying device that can stably stack sheets on an intermediate tray regardless of the sheet size.

(d) Means for Solving the Problems The present invention has been made in view of the above-mentioned circumstances, and is illustrated with reference to, for example, FIGS. There is a seat provided in the middle of the road (S)
an intermediate tray (183) for temporarily storing the sheets, and a carriage roller (20,
23) Carriage unit (1) with (57, 59)
(2), and the sheet (
The carriage rollers (20, 23
) is made constant regardless of the size of the sheet (S) to be discharged.

(E) Function Based on the above configuration, when discharging a small size sheet (S) onto the intermediate tray (183), the carriage unit (2) to which the sheet (S) is delivered is placed in the position shown in FIG.
is the seat (S) at the predetermined position (position of sensor 47) in
) is discharged. In addition, when discharging a large size sheet (S) onto the intermediate tray (183), the carriage unit (2
) discharges the sheet (S) at a predetermined position (position n of the sensor 47) in FIG. By setting the position at which the sheet (S) is ejected by the carriage unit (2) to be the same regardless of the size of the sheet (S), the discharge position of the sheet (S) by the carriage unit (2) is made to be the same regardless of the size of the sheet (S), so that it is not affected by the strength of the waist of the sheet (S) and the curl of the tip of the sheet (S). The sheets (S) are stably stacked on the intermediate tray (183) without any interference.

Note that the above-mentioned symbols in parentheses are shown for reference, and do not limit the structure of the present invention in the same manner.

(F) Example A first example of the present invention will be described below with reference to FIGS. 1 to 15. Components that are the same as those shown in FIGS. 40 and 41 are designated by the same reference numerals, and their explanations will be omitted.

FIG. 1 shows a copying machine P1 to which the first embodiment of the present invention is applied.
FIG. 1 to 5, on the downstream side of the flapper 185 there are disposed an intermediate tray ejection sensor 4 for detecting the sheet 3, an ejection roller pair 3, etc., and near the downstream side of the ejection roller 3. As will be described later, a first carriage unit 1 that grips and conveys the leading edge of a sheet S, and a second carriage unit 2 are disposed downstream of the first carriage unit 1. The carriage units 1 and 2 have a frame body 5 consisting of a bottom plate 5a and side plates 5b and 5c integrally provided on both sides of the bottom plate 5a.
A pair of rotatable rollers 6 is disposed on the upper outer surface of the rollers b and 5c, respectively.

The carriage unit 1.2 is constructed by loosely fitting the pair of rollers 6 into a pair of guide rails 7.8 fixed to both sides of the main body 151 of the copying machine. direction). A pair of belts 9 whose ends are connected to the side plates 5b and 5c of the first carriage unit 1 are each fixed to a shaft 11.12 and wound around a pair of pulleys 13.15,
A motor 16 capable of forward and reverse rotation is connected to the end of the shaft 11, and the carriage unit 1 is thereby
It is moved in the direction of arrow 17 or the opposite direction of arrow 19. Similarly, both side plates 5b of the second carriage unit 2
, 5c are wound around a similar pair of pulleys 13a, 15a, and are driven by another motor 16.

Both ends of the shaft 21 to which the plurality of carriage rollers 20 of the first carriage unit 1 are fixed are rotatably attached to the side plates 5b, 5c of the frame 5, and the side plates 5b,
The bases of a pair of support levers 22 are rotatably attached to both ends of the shaft 21 extending from the shaft 5c. A plurality of carriage rollers 23 forming a pair with the carriage roller 20 and a plurality of stiffening rollers 25 located between the carriage rollers 23 and having an outer diameter longer than the outer diameter of the carriage roller 23 are connected to a shaft 26. are fixed to each. Both ends of this shaft 26 pass through elongated holes 27 formed in the side plates 5b and 5c, respectively, and are attached to elongated holes 22a formed in the free end of the support lever 22.
2b to the shaft 21 side, that is, the carriage roller 23
is urged in a direction to press against the carriage roller 20.

The support lever 22 is biased at both ends counterclockwise in the figure by a tension spring 29 that is engaged with the side plate 5b and the support lever 22, and the shaft 26 is biased toward the rear end of the elongated hole 27 (the left end in the figure). ) is at rest in contact with.

In this state, the carriage roller 23 is in pressure contact with the carriage roller 20 in a vertical position, as shown in FIG.

An operating lever 30a of a deflection solenoid 30 is connected to the side edge of the support lever 22 opposite to the spring 29. When the deflection solenoid 30 is operated at a timing described later, the support lever 22 moves around the shaft 21. arrow 31
The shaft 26 rotates clockwise as shown by , and comes to rest with the shaft 26 in contact with the front end (the right end in the figure) of the elongated hole 27 . In this state, the carriage roller 23 slightly revolves in the paper feeding direction (to the right in the figure) while being in pressure contact with the carriage roller 20, as shown in FIG. Due to this revolution of the carriage roller 23, the tangential direction of the contact portion of the carriage roller 20.23, that is, the discharge direction of the sheet S, is slightly downward.

A motor 32 for driving the carriage rollers 20 and 23 is fixed to the side plate 5C of the frame 5, and gears 33 fixed to the output shaft thereof are fixed to the ends of shafts 21 and 26, respectively. It is connected to gear 36.

The base of an actuating member 42 is attached to a suitable position on the frame 5, and its free end extends upward from the frame 5, and this actuating member 42 is used to operate a sensor, which will be described later, when the carriage unit 1 is moved. It is what activates it. Furthermore, roller sensors 43 for detecting the sheet S are arranged before and after the carriage reelers 20, 23 of the carriage unit 1.

The second carriage unit 2 also has similar carriage rollers 57, 59, which are driven by the motor 16, and carriage roller sensors 60 for detecting the sheet S are installed before and after the carriage rollers 57, 59. It is arranged.

In the above configuration, the operation when making a half-size double-sided copy will first be explained with reference to FIGS. 6 to 10. In FIG. 1, the operation from the end of single-sided copying to the sheet S until the sheet S enters the switchback path 186 is the same as the operation of the conventional C-shaped bus shown in FIG. 31.

The first carriage unit 1 has an H
It is in a position to turn on the P sensor 46. The switchback roller 45 and the discharge roller 3 rotate in the directions of the arrows, and the sheet S is sent to the carriage unit 1 side. When the intermediate tray discharge sensor 4 detects the leading edge of the sheet S, the carriage roller 20.23 of the carriage unit 1 rotates. are rotated in the directions of the arrows by the rotation of the motor 32, and grip the leading end of the sheet S. At this time, the switchback roller 45 rotates together with the carriage rollers 20 and 23.

When the carriage roller sensor 43 in the first carriage unit 1 detects that the leading edge of the sheet S is held in the nip portion of the carriage rollers 20, 23, the motors 3, 2 are stopped and the carriage rollers 20, 23 are stopped. Rotation stops. Next, the motor 16 for movement in FIG.
At the same time, the switchback roller 4 starts moving in the direction of
5 rotates at a circumferential speed that is the same as the moving speed of the carriage unit 1. At this time, the second carriage unit 2
is stationary with the sensor 62 turned on.

When the actuating member 42 of the carriage unit 1 moving in the direction of the arrow 17 is detected by the sensor 61, a brake (not shown) is applied to the motor 16, and the carriage unit 1 comes to a standstill as shown in FIG. In this state, the carriage rollers 20.23 of the first carriage unit 1 and the carriage rollers 57.23 of the second carriage unit 2.
59 start rotating and insert the sheet S into the carriage unit 2.

When the sensor 60 detects that the leading edge of the sheet S is caught in the nip portion of the carriage rollers 57 and 59 of the carriage unit 2, the carriage unit 1 moves at a speed V in the direction of the arrow 19 as shown in FIG. , and the carriage unit 2 moves at a speed V in the direction of the arrow 17.
Move with.

Further, the sheet S held by the carriage unit 2 also moves at a speed V in the direction of arrow 17. Seat S at this time
Let V be the moving speed (process speed).

During the movement of the carriage unit 2, the carriage rollers 57 and 59 of the carriage unit 2 remain stationary and hold the sheet S in their mouths, but the carriage rollers 20 and 23 of the carriage unit 1 rotate at a circumferential speed (V+v). At this time, carriage roller 2 of carriage unit 1
Since a one-way clutch (not shown) is interposed in the gear 36 that is integrated with the gear 36, there is a slight difference in speed. The seat S will not be damaged due to the action of the clutch.

Due to the movement of the carriage unit 2, the actuating member 63 of the carriage unit 2 engages the paper discharge sensor 4 as shown in FIG.
7 is detected, a brake (as shown) is applied to the carriage unit 2, and the carriage unit 2 is stopped. Further, the deflection solenoid of the carriage unit 2 shown in FIG. 5 acts to cause the carriage roller 57 to revolve toward the sheet discharge side as shown in FIG. 19, with the discharge port facing slightly downward, and in this state, the carriage roller 57. 59 respectively rotate in the directions of arrows and discharge the sheet S. The carriage unit 2 returns at a speed V in the direction of an arrow 19 as shown in FIG. 10 while discharging the sheet S.

At this time, the moving speed of the second carriage unit 2 is V
, the discharge speed of the sheet S is V, so the carriage rollers 57 and 59 of the carriage unit 2 have a circumferential speed (V+v
) to rotate. When the carriage unit 2 is discharging the sheet S, the carriage unit 1 holds the next sheet S in its mouth and moves in the direction of arrow 17.

When the sheet S has been discharged onto the intermediate tray 183,
When a solenoid (not shown) is activated, the feeding roller 65 descends and comes into contact with the sheet S. Next, the deflection solenoid of the carriage unit 2 turns OFF, and the carriage roller 59 returns to its original position.

The above carriage unit 1.2 and carriage roller 2
0, 23, 57.59, etc. are determined by a control circuit (not shown).
In order to make the operation compatible with the half-size sheet S,
It is controlled by a control circuit (path shown).

1st. The second carriage units 1 and 2 return to the state shown in FIG.
The sheet S is separated from the sheet S on the intermediate tray (
(sheet storage means) 183. Intermediate tray 1
When the stacking of the sheets S on the sheet 83 is completed, the stacked sheets are aligned in the lateral direction by a width adjusting motor (not shown). During the refeeding of the sheet from the intermediate tray 183, it is similar to the conventional apparatus shown in FIG.
The sheets S are separated and conveyed one by one by the separation roller 66 on the downstream side, and then the second registration roller 7
The skew of the sheet S is corrected by conveying it while forming a loop between the sheet S and the separation roller 66 and between the second registration roller 70 and the second registration roller 70 .

Next, the operation when stacking large size sheets S will be explained with reference to FIGS. 11 to 15.

As shown in FIG. 11, the first and second carriage units 1 and 2 are stopped in a state where the sensors 46 and 83 are ONL, respectively, and the sheet S sent from the switchback roller 45 is connected to the carriage unit 1. Hold it with carriage unit 2.

As shown in FIG. 12, the carriage unit 2 moves to the position where the sensor 47 turns on while holding the leading edge of the sheet S in its mouth, while the carriage rollers 20 and 23 of the carriage unit 1 and the switchback roller 45 move the sheet S to the position where the sensor 47 turns ON. It rotates according to the speed of S (speed of carriage unit 2). As shown in FIG. 13, the carriage rollers 57 and 59 of the carriage unit 2 are turned downward and rotated to feed the sheet S by the deflecting means such as the solenoid 30 and the support lever 22. At this time, the carriage unit 1 stops the rotation of the carriage rollers 20 and 23, and moves together with the carriage unit 1 at the same speed as the sheet S.

A timer measures the timing when the leading edge of the sheet S comes below the feed roller 65, and after the leading edge reaches the bottom, a solenoid (not shown) turns ON and the feeding roller 65 is lowered onto the sheet S. and rotate it as shown in FIG. When a solenoid (not shown) for lowering the feeding roller 65 is turned on, the carriage unit 1 and the carriage unit 2 move in the direction of the arrow 19 while rotating the carriage rollers 20, 23, and 57 degrees S9. At this time, it is preferable that the carriage unit 2 returns as quickly as possible than the carriage unit 1 so that the rear end of the sheet S does not sag when the carriage unit 1 separates from the sheet S. Note that the peripheral speed of the carriage rollers 57 and 59 is the moving speed of the speed child carriage unit 2 of the sheet S. After the sheet S is discharged to the intermediate tray 183, the next sheet S is held in its mouth and dust is removed as shown in FIG.

The above carriage unit 1.2 and carriage roller 2
0, 23, 57.59, etc. are determined by a control circuit (not shown).
In order to make the operation compatible with the large size sheet S,
It is controlled by a control circuit (path shown).

A second embodiment of the present invention will be described as an operation of a large size sheet based on FIGS. 16 to 21.

As shown in FIG. 16, the carriage unit 2 is waiting at a location where the sensor 62 is turned on, as in the case of half size. The carriage unit 1 includes a carriage roller 20
．． 23 rotates and holds the sheet S in its mouth, then stops rotating, and in this state moves to a position where the sensor 61 is turned on, as shown in FIG. Carriage unit 1 passes the leading edge of sheet S to carriage unit 2 and moves in the direction of arrow 19 while rotating carriage rollers 20 and 23. ' The carriage unit 2 moves in the direction of arrow 17, turns on the sensor 47, rotates the carriage rollers 57 and 59, and returns in the direction of arrow 19 as shown in FIG. 18 while discharging the sheet S.

As shown in FIG. 19, just before the ejection of the sheet S is finished, the switchback roller 45 starts rotating and starts feeding the next sheet S toward the carriage unit 1. Immediately after turning on the sensor 83, the carriage unit 2 moves in the direction of the arrow 17 shown in FIG. 20 and enters the state shown in FIG. Repeat the condition.

FIG. 22 is a longitudinal sectional side view of an image forming apparatus to which a third embodiment of the present invention is applied.

In the image forming apparatus described above, one carriage unit 1 is disposed downstream of the discharge roller 3. In this case, one of the upper and lower carriage rollers 20 and 23 of the carriage unit 1, for example, as shown in FIG.
is necessary.

The above carriage unit 1 is shown in FIGS. 24 to 26.
The conveying and discharging operation of the sheet S will be explained. 26th
As shown in the figure, the carriage rollers 20, 23 stop rotating after gripping the sheet S discharged from the discharge roller 3. In this state, the carriage unit 1 moves in the direction of the sensor 47 as shown in FIG. 25, stops with the sensor 47 turned on, and moves in the direction of the arrow 19 while discharging the sheet S as shown in FIG. return. As shown in FIG. 27, even if the extending portion of the sheet S being discharged from the discharge roller 3 is supported by only one carriage unit 1, the waist is only supported by the roller 25. As a result of this action, the rear end of Sea 1-S is less likely to sag.

In the case of a large size sheet S, as shown in FIG. 27, when the carriage unit 1 turns the sensor 47 ONL, the trailing edge of the sheet S is held in the nip portion of the intermediate tray discharge roller 3. Carriage unit 1 is the 28th
As shown in the figure, since the sheet S moves in the direction of arrow 19 while being ejected, when the trailing edge of the sheet S passes through the ejection roller 3, the carriage unit 1 returns more than half the sheet size relative to the sheet S. Therefore, the rear end of the sheet S does not sag.

In the embodiment described above, the intermediate tray 1 of the copying machine main body 151
Although the case where the present invention is applied to No. 83 has been described, similar effects can be obtained when the present invention is applied to a circulation type document conveying device.

Here, a case will be described in which the present invention is applied to a circulating document feeder (hereinafter referred to as RDF).

FIG. 29 shows a longitudinal side view of the RDF. In the figure, a document 101 is placed on a document tray 102 with the document surface facing upward, and the document 101 is fed into the separation section B from the bottom by a half-moon roller 103 and a weight 105. The separation section B includes a separation belt 106
and a feeding roller 107, which separates the bottom sheet.

The separated document 101 enters the bus 110 and hits a pair of registration rollers 109, forms a predetermined loop, and is then conveyed by the pair of registration rollers 109 to a platen 117 on the main body side. A belt 111 wound around a driving roller 113 and a driven roller 112 is arranged to face the platen 117, and this belt 111 is pressed against the platen 117 by a plurality of press rollers 115. Manuscript 10 sent into the darkness between platen 117 and belt 111
1 is conveyed to a predetermined position at the end of the platen 117 (the left end in FIG. 29) by the movement of the belt 111, and then stopped.

Here, the original 101 is read by a reading means such as an optical system of the main body of the copying machine (not shown). When the predetermined reading of the original 101 is completed, the belt 111 moves again and sends the final original 101 into the path 119. And manuscript 1
01 is held in the large roller 120 and reversed, and the first
The document is transferred from the second carriage unit 121 to the second carriage unit 122, and is set on top of the stacked documents 101 with the document surface facing downward. Hereinafter, the same operation as above is performed for the remaining document 101,
One copy of the plurality of originals 101 is completed.

Note that path 123 is a bus for reversing a double-sided original, and reference numeral 125 is its switching flapper, which is not directly related to the present invention.

The first carriage unit 121 and the second carriage unit 122 are the carriage unit 1 described above.
, 2, and can transport the original 101 between the roller pairs, while being guided by a long hole 126 formed in the side plate of the RDF and moving in the forward and reverse directions shown by the arrows. It is possible. The first carriage unit 121 and the second carriage unit 122 make it possible to transport and discharge the original 101 while holding the original 101 between them.

The detailed operation of these carriage units 121 and 122 is the same as the operation of the intermediate tray 183 in the above-described embodiment, and thereby the RDF jam handling performance can be improved in the same manner as in the copying machine P8. can.

(G) As described in detail, according to the present invention, the seat storage means (
In a unit in which a carriage unit that pinches and conveys sheets is installed on a conveyance bus that conveys and discharges sheets to an intermediate tray, the position of the carriage roller that discharges sheets to the intermediate tray is determined by the size of the sheet to be discharged. By setting the same location regardless of the size of the sheet, it is possible to eliminate the curling phenomenon caused by the stiffness of the sheet being ejected due to its stiffness or the curling of the sheet tip, and it is possible to stably load sheets onto the intermediate tray. .

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional side view of an image forming apparatus to which a first embodiment of the sheet conveying apparatus of the present invention is applied, and FIG.
Perspective view of the second carriage unit and its drive unit, the third
The figure is a plan view, FIG. 4 is a front view of the carriage unit and rail, FIG. 5 is a perspective view showing the deflection means of the carriage unit, and FIGS. 6 to 10 are operation diagrams when conveying a half-size sheet. , FIGS. 11 to 15 are operation diagrams when conveying a large size sheet, FIGS. 16 to 21 are operation diagrams when conveying a large size sheet showing the second embodiment of the present invention, and FIG. 22 is an operation diagram when conveying a large size sheet. 23 is a perspective view of the carriage unit and its drive unit, FIGS. 24 to 28 are operational diagrams, and FIG. 30 is a vertical side view of a conventional image forming apparatus having an S-shaped sheet conveying device, and FIG. 31 is a C-shaped sheet conveying device. FIG. S...sheet, P...copying machine (image forming apparatus), 1...first carriage unit, 2...second carriage unit, 3...discharge roller, 4... Intermediate tray discharge sensor, 20.23, 57.59... Carriage roller, 43
．． 60... Carriage roller sensor, 46.47,
51, 61, 62... Carriage position detection sensor
, 183...middle tray. Figure 5 Figure 29 Figure 30

Claims (1)

[Scope of Claims] 1. A carriage unit having a sheet storage means provided in the middle of a sheet conveyance path for storing sheets, and a carriage roller that pinches and conveys the sheet as a means for conveying the sheet to the sheet storage means. A sheet conveying device characterized in that the position of the carriage roller when discharging the sheet to the sheet storage means is kept constant regardless of the size of the sheet to be discharged. 2. A plurality of carriage units each having a sheet storage means provided in the middle of a sheet conveyance path for storing sheets, and a carriage roller that pinches and conveys the sheet as a means for conveying the sheet to the sheet storage means; A sheet conveying device characterized in that the position of the carriage roller near the leading edge of the sheet is kept constant when the sheet starts to be discharged into the intermediate tray. 3. The sheet conveyance apparatus according to claim 2, wherein the plurality of carriage units are arranged in series with respect to the sheet conveyance direction. 4. The sheet conveying apparatus according to claim 1 and claim 2, further comprising a control circuit that changes the operation of the carriage unit and the carriage roller according to the size of the sheet discharged to the sheet storage means. 5. A sheet conveying device characterized in that when a sheet is discharged from a carriage unit to an intermediate tray, the carriage unit is moved in a direction opposite to the sheet discharge direction when the leading edge of the sheet reaches a predetermined position.