JP3191173B2 - Image forming device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of an automatic document feeder mounted on an image forming apparatus such as an electrophotographic copying machine, and more particularly, to an automatic document feeder for preliminarily feeding mixed originals of different sizes. Things.

[0002]

2. Description of the Related Art An automatic document feeder (ADF) is generally used by mounting it on a platen glass (platen glass) of an image exposure section of a copying machine or the like. In an optical system movable copier equipped with this automatic document feeder, the automatic document feeder feeds out one sheet at a time from a document table (stack section) on which a sheet-like document (hereinafter simply referred to as a document) is placed. The document is fed onto a platen glass by a transport belt, where it is exposed by an exposure unit lamp in the copier body, and is further conveyed to a document discharge table.

Conventionally, the operation of exchanging a document on the platen glass by such an automatic document feeder is conventionally performed by sending the next document from the stack section after detecting that the document on the document table has been discharged by a discharge sensor. The sheet was conveyed onto the platen glass and stopped at a predetermined position. For this reason, the document replacement time is increased, and thus the copy processing time is required, and the copy productivity is reduced.

[0004]

At the time of a document exchange operation for automatically feeding and discharging a document onto a document table using an automatic document feeder, the document exchange is performed within the return time of the scanning optical system of the copying machine body. If done, the copy productivity would be 100% and no time would be required. For this purpose, it is necessary to increase the document conveyance speed from the document double feed prevention position of the stack portion to the document platen stop position on the platen glass surface. However, when the document conveying speed is increased, various problems such as an increase in the size of the motor, an increase in power consumption, generation of noise, abrasion of the conveying belt, an increase in the degree of document breakage, and a decrease in document separation performance occur.

Japanese Unexamined Patent Publication No. 1-236136 discloses a prior art document feeder which eliminates the above-mentioned problem and reduces the time required to replace a document without increasing the document feed speed.

This document feeder stops feeding the first document to a predetermined position, and then stops feeding the second document to a position adjacent to the predetermined position and not on the upstream platen glass. The first document that has undergone the image reading process is transported to a downstream position on the platen glass adjacent to the predetermined position where the transport device can transport the first document, and at the same time, the second document is stopped transporting to the predetermined position. The third and subsequent originals are characterized in that the operation is stopped sequentially by repeating this procedure (flying original conveying system).

Further, the original feeding method of a copying machine disclosed in Japanese Patent Application Laid-Open No. 60-140364 is a three-sheet original simultaneous feeding method. The speed can be increased.

According to the above-described copying machine, the size of the original is detected in association with the automatic feeding of the original, and the copy paper is fed according to the size detection. If the originals are all the same size, the feeding of the next copy sheet can be performed in advance by the detection of the first original size regardless of the feeding of the next original. However, if documents of various sizes are mixed at random, each time the documents are separated and fed,
It is necessary to detect the size of the document and to selectively feed copy paper in accordance with the size, so that preliminary preliminary feed of copy paper becomes impossible, and the copy speed is reduced.

In a copying machine provided with the above-mentioned automatic document feeder, in a side loading type paper feeding means for mounting a paper feeding cassette from the side of the copying machine main body, copying is performed from the leading end of the paper feeding cassette on the downstream side of the paper feeding. Since the distance to the registration rollers of the paper feeding device of the machine body is relatively short, the recording paper is taken out from the corresponding paper feeding cassette based on the generation of the size detection signal of the original on the loading table in the automatic document feeder, and The time required to reach the registration roller is similar to the time required for the document to reach the stop position on the platen glass. When documents of a plurality of sizes are mixed, it is not necessary to particularly shorten the document replacement time.

However, a paper feeding device having a large distance from a feeding start position (recording paper front end portion) to a registration roller by a paper feeding cassette, for example, a paper feeding device of a front paper feeding cassette system (a front loading system shown in FIG. 1). In a large-capacity paper feed tray (LCT) paper feed, the recording paper feed time required for the recording paper sent from the paper feed cassette (or paper feed tray) to reach the registration rollers increases. For this reason, even if the next original arrives at a predetermined position on the platen glass, the corresponding recording paper does not reach the predetermined position of the image forming unit, and copy productivity = {the number of originals processed per minute ( OPM)｝ decreases. In particular, in a high-performance copying machine capable of high-speed processing in which the image forming processing speed and the document conveyance speed are improved, the above-described recording paper feeding delay becomes a problem.

In a copying machine equipped with an automatic document feeder disclosed in Japanese Patent Application Laid-Open No. 64-34821, the temporary standby position by the paper feeding means is a size for detecting the size of one preliminary-fed original. The paper is selectively fed according to the detection signal of the detection means.

However, this automatic document feeder can detect only the size of the document immediately before the one sent to the exposure processing section. Therefore, in an automatic document feeder capable of pre-feeding a large number of small-size documents in the feeding path (flying feed),
Since the size detection is delayed, it is impossible to shorten the document exchange time.

[0013]

SUMMARY OF THE INVENTION The present invention solves the above-described problem of document conveyance in an image forming apparatus provided with an automatic document conveyance device, and achieves a reduction in document exchange time while ensuring document conveyance reliability. The purpose is to improve the recording paper feeding timing.

That is, during the preceding document exposure, the size of the next document and the size of the next document are detected at the time of flying paper feeding in which a plurality of documents are sent to the temporary stop position in advance, so that the recording paper feeding timing of the image forming apparatus is detected. The purpose of this is to improve copy productivity by improving.

An object of the present invention to achieve the above object is to provide a document stacking section for stacking a plurality of documents of different sizes, a sheet feeding section for feeding out the documents on the document stacking section and separating and feeding them one by one. An automatic document feeder having transport means for transporting the document from the paper feed unit to an exposure position, and a discharge roller for discharging the document from the exposure position to a discharge tray. An image formed on a photoreceptor of an image forming unit, developing the latent image to form a visualized image, and transferring the visualized image onto recording paper selected and fed from a plurality of paper feed cassettes; In the forming apparatus, a standby position for waiting for a document to be pre-fed is provided between the paper feeding unit and the exposure position, and the size of each document is sequentially detected and stored at the time of preliminary paper feeding to the standby position. Document size detection means and storage means Paper feed means for feeding recording paper to the image forming unit in response to a size detection signal from the document size detection means and the storage means, and a recording paper corresponding to the size of each document stored in the storage means; This is achieved by an image forming apparatus including a control unit that controls so as to perform preliminary sheet feeding.

[0016]

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is an overall configuration diagram of an image forming apparatus (copier) equipped with an automatic document feeder according to the present invention.
In the figure, 1 is a copying machine main body, 2 is a scanning exposure optical system, 3
Denotes image forming means around the photosensitive drum 31; 4A, 4B, 4
C and 4D are recording paper supply means (paper supply means), 5 is a recording paper transport means, 6 is a fixing device, 7 is a reverse discharge switching means, 8 is a reverse transport means, and 9 is a double-sided recording paper transport means (ADU). , 10 are automatic document feeders (ADF). In the drawing, a dashed line indicates a feeding path of the recording paper.

FIG. 2 shows an automatic document feeder 1 according to the present invention.
FIG. 3 is a configuration diagram showing a drive system (power transmission system) of the automatic document feeder. Automatic document feeder 1
Reference numeral 0 denotes a document loading unit which is installed on the copying machine main body 1 as shown in FIG.
A sheet feeding unit 12 that separates and feeds the originals D, an intermediate conveying unit 13 that conveys the originals D fed from the sheet feeding unit 12 to a predetermined position on a platen glass 21, and a conveying unit 14
After the image exposure is completed, the document D sent from the conveying means 14 is discharged to a paper discharge tray 158 or a post-processing device, and the document in the image exposure section is reversed and fed again onto the platen glass 21. And a reversing unit 15.

A stack tray (original mounting table) 110 for stacking a stack of originals is fixedly mounted on the original mounting portion 11. On the stack tray 110, a width regulating plate 111 for restricting the width of the original is provided. It is provided movably.

When the document bundle D is placed on the stack tray 110, the presence or absence of a document on the stack tray 110 is detected by a document presence / absence detection means (document zero sheet sensor) PS1. The mode is displayed. When the document sizes of the document bundle D are the same, the document size (for example, B5 to A3) is detected by the document width detection sensor PS2 and input to the control unit of the copying machine body 1.

A movable pressing plate 112 is swingable around a swing shaft 114 at the leading end side of the stack tray 110 at the document feeding downstream. A drive plate 118 is screwed to the swing shaft 114, and can swing integrally. An elastically deformable member (for example, a torsion spring) 119 is wound around the swing shaft 114, and the both ends thereof can press the drive plate 118 and the center thereof can press the movable pressing plate 112. The driving plate 118 is provided with two actuator units, and one of the actuator units is a pressing sensor (for example, a photo interrupter) PS fixed to the movable pressing plate 112.
The optical path of No. 3 is turned on / off. The other actuator unit turns on and off the optical path of the pressing home position sensor PS4 fixed to the fixed bottom plate 116, and detects the home position of the driving plate 118.

A feeding section 12 is provided on the downstream side of the movable pressing plate 112 in document feeding. The paper feeding unit 12 includes a document leading end stopper 120, a driving roller 121, a driven roller 122, a feed belt 123 that winds and rotates these rollers, and a double feed prevention reverse roller 124 located below the feed belt 123. I have. The driving force of the driving motor M2 is transmitted to the driving roller 121 via an electromagnetic clutch CL1.

An original size sensor PS8 for the mixed original mode is provided downstream of the nip position where the field belt 123 and the reverse roller 124 come into contact with each other. When one sheet of original is sent from the bundle of originals D stacked on the stack tray 110 by the paper supply unit 12, the size of the original (B5 to A3) is detected by the original size sensor PS8. Input to the control unit. Hereinafter, the mixed mode original will be described.

FIG. 4 shows the placement positions of documents of various sizes that can be mixed on the stack tray 110 and a document size sensor PS8.
It is a top view which shows installation. Various sizes (B5 to A3)
Are abutted on the stack tray 110 with a document leading edge reference surface B orthogonal to the sheet feeding direction A and a document width direction reference surface C orthogonal to the reference surface B, and are positioned on a one-side basis.

The original size sensor PS2 is provided in parallel with the original leading edge reference plane B, and non-contact sensors (for example, optical sensors) S1, S2, S3, S4, S5, and S6 are arranged in a row. The sensor S1 is a B5 size landscape document (B
5R), the size of the B5R document is detected by blocking the optical path and detecting the passage of the document.
Similarly, the sensor S1, S2 located at the middle in the width direction of B5R and A4R indicates the size of the A4R document, sensors S1, S2 and S3 indicate the size of the B5 document, and sensors S1 and S1
2, S3 and S4 indicate the size of the A4 document and the sensors S1, S
2, S3, S4 and S5 indicate the B4 document size and the sensor S
1, S2, S3, S4, S5, and S6 identify A3 document sizes, respectively. FIG. 5 is a flowchart showing the document size detection operation described above.

FIG. 6 is a block diagram showing an example of a control circuit configuration in the original placing mode. Microcomputer (C
The PU 100 performs control according to a control program stored in the ROM 101 in advance. The RAM 102 is used as a buffer memory, flags, and other calculation areas. Reference numeral 103 denotes an input device for setting the mixed document mode. 1
Reference numeral 04 denotes a copy magnification setting input means and a magnification output control means. These detecting means, input / output means and control means control the document flying paper feeding means 105 and the recording paper feeding means 1.
06 is controlled.

An intermediate transport section 13 is provided on the downstream side of the document transport section 12 from the document transport section. The intermediate transport unit 13 includes a first intermediate transport roller pair 130 driven forward and forward, a document passage detection sensor PS5, a curved guide plate 131, and a second intermediate transport roller pair 132 driven forward and reverse. A transport path for transporting the document D sent from the feeding unit 12 to one end of the platen glass 21 is formed.

On the surface of the platen glass 21, a transport belt 141 is rotatably stretched between a driving roller 142, a driven roller 143, three document pressing rollers 144, and a tension roller 145. A clutch CL2 and a brake BRK are supported on the shaft of the driving roller 142, and are operated by the driving force of the driving motor M2.

The paper discharge reversing section 15 includes a paper discharge roller 150, a switching claw 1
51, a plurality of transport rollers 152, 153, 154 and a guide plate 15
5, 156, 157, etc. The discharge roller 150 and the transport rollers 152 to 154 are driven by a discharge motor M3. The discharge roller 150 and the transport roller 152 are driven to rotate forward and the transport rollers 153 and 154 are driven to rotate forward and reverse. The switching claw 151 is driven by a solenoid SOL.

At a predetermined position of the movable pressing plate 112, a document presence / absence detecting means (document zero sheet sensor) PS1 is fixedly provided in the vicinity of the reverse roller 124 for preventing double feeding of the sheet feeding section 12. The installation position of the sensor PS1 is set to a position where the rear end of the original passes through the sensor PS1 and waits when the original on the original mounting table is in a flying original feeding operation described later.

(A) to (H) shown in FIG. 7 and FIG.
FIG. 9 is a schematic diagram illustrating an operation process of feeding, transporting, and discharging a plurality of small-size originals D1 to D5.
1 shows a transfer route of the first embodiment. FIG. 9 shows an automatic document feeder (A
3D is a time chart of a document feeding / conveying operation process of FIG.

Hereinafter, mixed originals of different sizes (A3 size to
The document feeding operation (B5 size, etc.) will be described.

(A) FIG. 7A is a schematic diagram showing a document transport path of the automatic document transport apparatus in which the above-mentioned document bundle is placed and in a feeding preparation state. In the figure, the image recording surfaces of a bundle of originals (five originals D1 to D5 in the drawing) are placed upward at a predetermined position on the stack tray 110 and the movable pressing plate 112, so that the automatic original feeder 10 Starts and AD
The mode is set to F mode.

(B) Next, when the copy button on the control panel of the copying machine body 1 is turned on, the pressing motor M1 is started, the movable pressing plate 112 is raised, and the uppermost surface of the original bundle is fed. The drive motor (main motor) M2 is turned on almost simultaneously with the belt 123, and the electromagnetic clutches CL1 and CL2 are also turned on almost simultaneously, so that the document feeding is started. That is, the upper-layer document is sent out by the feed belt 123 which has started to rotate by the driving force of the drive motor M2, and only the uppermost document D1 out of the plurality of documents output by the reverse roller 124 is used. Separated and fed.

One original D1 separated and fed as described above
The document size is identified by detecting in the width direction by a document size sensor PS8 provided downstream of the reverse roller 124 (see FIG. 7B). That is, non-contact sensors (for example, photo sensors) S1, S2, S3, S4, S provided in the unit of the document size sensor PS8
5 and S6 detect the passage of the leading edge of a single document that is separated and fed, thereby detecting the size of the document, and inputting a detection signal to a control unit in the main body 1 of the machine. For example, B5R
When the document passes the document size sensor PS8, the sensor S
1 interrupts the optical path and generates a detection signal. When passing the A4R document, the sensors S1 and S2 generate a size detection signal. Similarly, the sizes of B5, A4, B4, and A3 are detected by passing through the sensors S1 to S6 (see FIG. 4).
This document size detection signal is sent to the control unit of the copying machine main body 1, and the corresponding recording paper is preliminarily fed. At this time, if the automatic magnification selection function (AMS) is set, the magnification is automatically selected according to the document size and the set recording paper size. If the automatic paper feed selection function (APS) is set,
The recording paper size corresponding to the document size is selected and the paper is prepared for feeding (see FIG. 5).

(C) One sheet of the document D1 that has passed through the document size sensor PS8 and is continuously fed by the feed belt 123 is nip-conveyed to the first pair of intermediate conveyance rollers 130, and the leading end of the document D1 is detected. When the sensor CL crosses the sensor PS5, the clutch CL1 that has driven the driving roller 121 is turned off, and the feed belt 123 is driven and rotated until the rear end of the document D1 passes through the sensor PS5, and then stops. The document D1 is transported by the first intermediate roller pair 130.

The first original D1 sent out by the paper supply unit 12 and transported by the first intermediate transport roller pair 130
Is passed through the guide plate 131 and fed by the second intermediate transport roller pair 132 downstream thereof, and is further fed between the guide plate 133 downstream thereof. Feeded through.

Next, in the conveying means 14, the sheet is conveyed while being clamped between the rotating conveying belt 141 and the platen glass 21, the driving of the drive motor M2 is controlled by a timer, and the original D1 is It stops at the position (see FIG. 7C).

(D) Next, under the control of the timer, the drive motor M2 is driven and rotated, the field belt 123 is rotated, and the following original D2 is sent out. The size is detected by the original size sensor PS8. The signal is sent to the control unit of the copier body 1 and the storage means (RAM) 108
And then prepares for the next recording paper feed. First
After being nipped by the intermediate conveyance roller pair 130, the operation is temporarily stopped. During this time, the transport belt 151 is stopped, and the preceding document D1 is stopped at an intermediate position on the platen glass 21. In this stopped state, the distance between the trailing edge of the preceding document D1 and the leading edge of the succeeding document D2 is set to be a predetermined distance (for example, 40 mm) (see FIG. 7D).

(E) Subsequently, the drive motor M2 starts rotating by the count-up of the timer, and the first intermediate roller pair
130, the second pair of intermediate rollers 132, and the conveyor belt 141 rotate at a constant speed, sandwich the preceding original D1 and the succeeding original D2, slide on the platen glass 21, and transport them. As a result, the document D1 stops at a position where the leading end of the document D1 comes into contact with the document stopper 22 projecting from the upper surface of the left end of the platen glass 21 in the drawing, and waits. In this stopped state, the distance L between the trailing edge of the document D1 and the leading edge of the document D2 is still kept at a predetermined distance (see FIG. 7E).

(F) The document D1 is exposed at the stop position on the platen glass 21 by the exposure lamp 23 of the scanning exposure optical system 2, and a document image is formed on the photosensitive drum 31 via a lens, a mirror, and the like. . Then, the same exposure is repeated for the set number of copies, and a series of copy processes for the document D1 is performed.

During the above-mentioned exposure operation, by timer control,
The drive motor M2 and the clutch CL1 are operated, and the feed belt 123 and the first intermediate transport roller pair 130 start rotating, send out the next original D3, and detect and store the size of the original D3 by the original size sensor PS8. Then, under the control of the timer, the leading edge of the document D3 advances to a position where a predetermined distance L1 is maintained from the trailing edge of the preceding document D2 and stops (see FIG. 8F). .

(G) After the exposing operation of the original D1, the transport belt 141 is rotated by the rotation of the drive motor M2, and the exposed original D1 passes through the paper discharge reversing unit 15 and is set on a paper discharge tray outside the machine. 158. Next document D waiting at the same time
8 is slid on the platen glass 21 and stopped at the stop position of the document stopper 22, and the conveyance of the subsequent document D3 is stopped at the halfway standby position by the same operation as described above (FIG. 8).
(G)).

(H) During the exposure operation of the original D2, the next original D4
And the size is detected, and the distance L from the rear end of the preceding original D3 is
(See FIG. 8H).

(I) After the exposure of the original D2 is completed, the exposed original D2 is discharged, and at the same time, the original D3 which is waiting on the platen glass 21 is conveyed to the exposure position.
The subsequent document D4 is transported to the intermediate standby position while keeping the interval L, and is made to wait.

In the document feeding process described above, documents of different sizes are vertically placed on the stack tray 111 on one side basis. However, the same applies to an automatic document feeder in which documents are placed horizontally. Applicable to

Next, a description will be given of a second embodiment of the image forming apparatus provided with the automatic document feeder according to the present invention.

In the first embodiment, the original size sensor PS8 having six sensors is used, and the original size is detected by sending out the original. There is a problem that the size cannot be detected unless the paper operation is started, and a timing delay occurs.

On the other hand, generally, manuscripts are JIS standard A series and B
It is extremely rare to copy a series. Also, due to filing reasons, there are many cases where A3 size and A4R size are mixed and B4 size and B5R size are mixed. Therefore, the second embodiment of the present invention enables to quickly detect the discrimination between the A3 size and the A4R size or the B4 size and the B5R size.

FIG. 10I is a schematic plan view showing a state in which A3 size and A4R size of the JIS standard A series are mixedly mounted on the stack tray 110 and aligned. Fig. 10 (II) shows the JIS
FIG. 9 is a schematic plan view showing a state where standard B series B4 size and B5R size are mixedly mounted on a stack tray.

The A-series mixed original bundle is stacked on a stack tray.
The original (A3) having the maximum width is pressed against the document leading edge reference surface B and the document width direction reference surface C on the reference surface 110 and is aligned by the first document size detecting means of the lateral width regulating plate 111. Similarly, when the B-series mixed document bundle is aligned on the stack tray 110, the sheets are aligned by the reference planes B and C and the width regulating plate 111.

Below the width regulating plate 111, a width detecting sensor (first document size detecting means) PS2 is provided, and detects the maximum width of the mixed original bundle based on the moving distance of the width regulating plate 111.

On the downstream side of the reverse roller 124,
A document size sensor PS9 as one second document size detecting means is fixed. The position of the document size sensor PS9 as the second document size detecting means in the width direction is set to be 210 mm or more from the reference plane B in the case of the A series.
The position may be 0 mm or less, but also considering the placement of the B-series original, 210 mm (A4R width) or more from the reference plane B to 364 mm
mm (B4 width) or less.

By providing the first and second document size detecting means in this way, first, by moving the width regulating plate 111, the width detecting sensor PS2 detects the maximum width of the A series or the B series, and A3, B4 is identified, and when the document feeding is started, the document size sensor PS9
Through the passage, a wide A3 size or a half-width narrow A4R is identified. Similarly, the B4 size and the B5R size are identified by the document size sensor PS9. In this manner, the size of mixed originals can be quickly and inexpensively realized by a small number of original size detecting means.

FIG. 11 is a schematic plan view for explaining the position of the original document of the USA planned size and the arrangement of the original size detecting means.
In the drawing, letter size (11 ″ ×
8.5 ") and legal size (14" x 8.5 ") are mixed. In this case as well, the width detection sensor P as the first document size detection means is also used as described above.
Both sizes can be identified by using S2 and a document size sensor PS9 as a second document size detecting means. At this time, the position of the document size sensor PS9 as the second document size detecting means in the width direction is 297 m.
The position is not less than m (11 ") and not more than 356 mm (14").

The above is the process of transporting a single-sided document. The same operation can also be used to improve the document transport characteristics in a double-sided document copy mode (RADF). It is obvious that the same operation can be performed by an RADF having a U-turn reversal path on the paper discharge side, a circulating document feeder (RDH), or the like.

[0058]

According to the image forming apparatus provided with the automatic document feeder of the present invention, when a plurality of types of originals having different sizes are mixed and fed separately on the automatic document feeder original mounting table, Since the size can be detected at an early stage, the recording paper corresponding to the document size can be preliminarily fed. In particular, in the flying paper feed format, which shortens the document exchange time, the size of the next document and the next document can be detected during the exposure process, so that the functions of the automatic document feeder can be fully demonstrated and the recording paper feeding can be performed. The timing can be made faster, the paper feed time can be shortened, and copy productivity can be improved.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of an image recording apparatus equipped with an automatic document feeder according to the present invention.

FIG. 2 is a sectional view of the automatic document feeder according to the present invention.

FIG. 3 is a drive system (power transmission system) of the automatic document feeder.
FIG.

FIG. 4 is a plan view showing mixed positions of various size originals and an arrangement of original size sensors.

FIG. 5 is a flowchart illustrating a mixed document size detection operation.

FIG. 6 is a block diagram illustrating an example of a control circuit configuration in a mixed original mode.

FIG. 7 is a schematic diagram illustrating an operation process of feeding, transporting, and discharging a plurality of documents.

FIG. 8 is a schematic diagram of the document conveying operation process.

FIG. 9 is a time chart of a document feeding process.

FIG. 10 is a schematic plan view illustrating the position of a document in the A-column and B-column sizes according to JIS standards and the arrangement of the document size detection unit.

FIG. 11 is a schematic plan view illustrating a position of a document of a USA standard size and an arrangement of a document size detecting unit.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Copier main body 2 Scanning exposure optical system 21 Platen glass 23 Exposure lamp 3 Image forming means 10 Automatic document feeder 11 Document placement unit 100 Microcomputer (CPU) 110 Stack tray (document loading table) 111 Width control plate 112 Movable pressing Plate 12 Paper feed section (paper feed means) 13 Intermediate transport section 130 First intermediate transport roller pair 132 Second intermediate transport roller pair 14 Transport means 141 Transport belt 15 Discharge reversing section A Paper feed direction B Document top reference plane C Document Reference planes in the width direction D, D1 to D5 Document L Document interval M2 Drive motor (main motor) PS1 Document presence / absence detection means (zero document sensor) PS2 Document width detection sensor (first document size detection means) PS5 Document passage detection sensor PS8 Document size sensor (mixed size document mode) PS9 Document size sensor (second document size detecting means) S1, S2, S3, S , S5, S6 sensor

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) G03G 21/00 370-540 G03G 15/00 107 G03G 15/00 510-534 B65H 3/44 342

Claims (1)

(57) [Claims] An original loading section for loading a plurality of originals of different sizes, a paper feeding section for feeding out the originals on the original loading section and separating and feeding the originals one by one; An automatic document feeder having a transporting means for transporting the document and a discharge roller for discharging the document from the exposure position to a discharge tray, wherein a latent image for the document image is formed on a photosensitive member of an image forming section; The latent image is developed to form a visible image, and the latent image is pre-fed in an image forming apparatus configured to transfer the developed image onto recording paper selected and fed from a plurality of paper feed cassettes. A document size detection means and a storage means, wherein a standby position for waiting for a document is provided between the paper supply unit and the exposure position, and sequentially detects and stores the size of each document at the time of preliminary paper feeding to the standby position. , The document size detecting means and a memory Paper feeding means for feeding the recording paper to the image forming unit in accordance with the size detection signal by the step, and control to select a recording paper corresponding to the size of each document stored in the storage means and to carry out preliminary paper feeding An image forming apparatus, comprising: