JPH0624599A - Automatic document feed device - Google Patents

Abstract

PURPOSE:To prevent the floating of the rear ends of copies from a platen, and to realize a good positioning accuracy, by shorten the effective length of a conveying means in order to make the rear ends of all the copies inserted under a covering means, and providing a conveying sensor at the position to detect the front ends of the copies when the rear ends of them come to a specific position of the platen. CONSTITUTION:A reading standard point is provided at the exhaust side of a platen P, and the interval with a neighboring member Y is made shorter than the length of small copies processed by the device. And a paper exhaust sensor S3 is set at the position to detect the front ends of the copies of all sizes when the rear ends of various sizes of copies reach to stopping standard points Q3 to Q5. After the rear ends of the copies reach on the platen P, the conveying means is moved inversely, and the conveying amount of the conveying means is controlled from the time when the front ends of the copies pass the sensor S3 again, so as to set the front ends of the copies to the setting standard position on the platen P. Consequently, even in the smallest size of copy, its rear end is held by a platen 31 without fail, and the rear end of the copy is never floated up.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic document feeder which automatically feeds originals one by one onto a platen of an image processing apparatus such as a copying machine, and more particularly, by a conveying means for conveying a part of the platen. The present invention relates to a so-called half-belt type that covers the platen and covers other portions of the platen that are not covered by the conveying means by a cover means provided adjacent to the conveying means.

[0002]

2. Description of the Related Art As is well known, there are various sizes of originals sent onto a platen of an image processing apparatus. For this reason, conventionally, it has been general to provide a conveying unit having a size corresponding to the maximum size original document expected in the processing apparatus, and cover the original document on the platen by the conveying unit. However, there are various manuscript sizes,
Normally, the size of the manuscript that is frequently handled is a specific size, such as A4 size / B5 size in Japan, and litter size slightly larger than A4 in foreign countries, and the size of the manuscript handled by the image processing device is relatively small. There are many. As described above, a document of A4 / letter size or less, which is relatively frequently used, is a small size document (hereinafter referred to as an S size document or S size document).
Called manuscript. Similarly, a large size document will be referred to as an L size document or an L document. ), It is not very costly to attach a large conveying means for L originals, and the conveying distance of the originals becomes large, which is disadvantageous in terms of processing time. Moving them in contact with each other may damage the original and generate unnecessary static electricity, which may cause trouble.

In recent years, paying attention to the above problems, the conveying means has a small size corresponding to an S original having a relatively large throughput, and a platen other than the platen is provided adjacent to the conveying means for L original processing. A so-called half-belt type having a cover means for covering the portion has come to be provided.
Although there are various types of half-belt type automatic document feeders, the document is fed below the transport means through the adjacent portion between the transport means and the cover means, and the L document is switched back. The structure in which the device is inserted under the cover means has an advantage that the entire device is well organized and the device occupying area is small and can be easily configured.

[0004]

By the way, in the past, the conveying means was constructed so as to correspond to a specific S original, and when the specific original was processed, it was covered only by the conveying means without a switchback operation. This has the advantage that the processing speed can be improved without the switchback operation time. However, the adjacent portion between the conveying means and the cover means also serves as a conveying path for the original document, and there is a gap in this portion, and the rear end portion of the original document does not come into close contact with the platen at this portion, and the light is not emitted during exposure. However, there is a problem in that the black line is not reached and the image quality is deteriorated.

The present invention has been made in view of the above-mentioned problems of the prior art. The original replacement cycle speed on the platen is not lowered so much, and the trailing edge of the original is always in close contact with the platen. Does not appear, the localization accuracy of the original is high,
At the same time, it is an object to provide an automatic document feeder which can be manufactured at a lower cost.

[0006]

In order to achieve the above object, according to the present invention, a conveying means which is placed so as to cover a part of a platen of an image processing apparatus, and which conveys an original on the platen, is adjacent to the conveying means. And a cover means for covering the other part of the platen, and a document which is taken in between the conveying means and the cover means and discharged from the other end of the conveying means is conveyed by the reverse conveying of the conveying means. In the automatic document feeder which inserts a part of the document into the lower part of the cover means and sets the document at the image processing position on the platen, after the rear end of the document reaches the platen, the document is reversed. The original is set at the image processing position on the platen by feeding a part of the original between the cover means and the platen, and the platen of the original set at the image processing position on the platen is also set. An automatic document feeder provided with the cover means in position for restricting floating of uptake transport direction rear end portion of the. It should be noted that the cover means is fixed to the platen surface at a position having a gap into which a document can be inserted, or is slidably supported or vertically supported. Also,
Specifically, it is implemented by the following control method.

One of them is to provide a sensor means at a position where the leading edge of the original can be detected when the trailing edge of the original captured on the platen is introduced onto the platen.
After the trailing edge of the original reaches the platen, the conveying means is reversely fed, and the conveying amount of the conveying means is controlled from the time when the leading edge of the original is detected by the sensor again, and the leading edge of the original is moved. A method of providing a control means for setting the image processing position on the platen.

Secondly, the document size detecting means for detecting the size of the document to be taken in on the platen is provided, and the leading end of the document in the taking-in direction exceeds at least the set reference position on the platen for setting the leading end. The rear end stop reference position of the original is set to the position, and the rear end of the original is conveyed to the rear end stop reference position on the platen according to the size information of the original size detecting means, A method of providing a control means for setting the original at a setting reference position on the platen by reverse conveyance. At that time, the trailing end stop reference position is set at the same point on the platen where the trailing ends of the originals of all sizes captured by the conveying means stop, and when the leading end of the originals captured by the conveying means is set at the platen. It is conceivable that a plurality of sets may be set according to the stop position on the platen at the rear end of the document at a position that exceeds the upper set reference position by a predetermined distance.

Thirdly, the document size detecting means for detecting the size of the document taken in on the platen, and the state in which the rear end of the document taken in on the platen is introduced on the platen, A sensor means is provided at a position capable of detecting the leading end portion, and a trailing end stop reference position of the original document is set at a position where the leading end portion in the document taking direction exceeds at least a set reference position on a platen for setting the leading end portion. Then, after the trailing edge of the document reaches the platen, the transporting means is reversely fed, and the transport amount of the transporting means is controlled from the time when the leading edge of the document again passes the sensor means, and the leading edge of the document is controlled. The rear end portion of the document on the platen according to the size information of the first size control means and the document size detection means. After conveyed to, and a method of performing provided a second control means for setting the document in a set reference position on the platen by the reverse conveyance of the conveying means.

[0010]

Although the present invention can be applied to various image processing apparatuses, an automatic document feeder applied to a copying machine will be described here as an example.

As shown in FIG. 1, the automatic document feeder 10 placed so as to cover the platen P of the copying machine M has a conveying means for covering an area smaller than half of the platen P, for example, a conveying section 20, and also the platen. A cover means 30 for covering the remaining area of P, a separating / feeding section 50 provided above the cover means 30 for separating and feeding the original set in the sheet feeding tray section 40 toward the platen P, and a conveyance. A paper discharge unit 60 including a discharge unit that receives the exposed document conveyed by the unit 20 and discharges it from the platen P, a paper discharge tray unit 70 that stores the document discharged by the paper discharge unit 60, and automatic document feeding A hinge unit 80 and a control unit 90 that support the apparatus 10 above the platen P of the copying machine M so as to be openable and closable.
It has and.

FIG. 3 shows a state in which the automatic document feeder 10 of FIG. 1 is opened above the platen P, and the effective reading range (reading section T: length X-Z) is defined on the upper surface of the platen P. Therefore, one end of the reading unit is used as a document set reference, for example, a reading reference point X (this reference point X may be indicated as Q1 for the purpose of matching with various reference points).
At the time of copying, by arranging one end of the manuscript D with this reference point X, a copy corresponding to the manuscript can be obtained. The reading unit T has the maximum size that can be copied, and is indicated by a chain line in the drawing. For example, double letter size (279.
4 mm x 431.8 mm) is the maximum size that can be copied. It should be noted that it is possible to use small size documents, but here we assume that the assumed small size document is B5 size (2
10mm x 297mm) horizontal insertion (B5 side) is assumed (see Fig. 13).

FIG. 2 shows two drive motors M1 and M2 of the automatic document feeder 10, sensors S1 to S5 for collecting information necessary for control, and a control board 99 of the control unit 90. There is. The drive motor M1 is a separate feeding unit 50.
Is mainly connected to the empty sensor S.
1. The drive is controlled based on the output signal from the open / close detection sensor S5. On the other hand, the drive motor M2 is drivingly connected to the transport unit 20, and mainly includes a registration sensor S2, a detection sensor (paper discharge sensor) S3 for detecting the leading and trailing ends of the document in the paper discharge unit 60, and an output shaft of the drive motor M2. Drive control is performed based on an output signal from a photo sensor S4 that detects a rotation amount of an interrupter 971 (described later) provided on the 96.

As shown in FIGS. 4 and 5, the automatic document feeder 10 has a paper feed tray section for stacking documents from upstream (right side in FIG. 4) to downstream (left side in FIG. 4) in the document conveying direction. 40, a separation feeding unit 50 that separates and conveys the original document on the tray into one sheet, and a conveyance unit as a conveyance unit that receives the original document conveyed by the separation feeding unit 50 and further conveys it to the downstream side. And 20 are provided. A cover means 30 is provided below the separating / feeding unit 50 on the platen P side, and above the downstream side of the transporting unit 20, the document received from the transporting unit 20 is transported while being turned upside down. A paper unit 60 is provided. Above the separating / feeding unit 50 and the conveying unit 20, a paper discharge tray unit 70 for storing the documents discharged by the paper discharge unit 60 is provided. The paper feed tray unit 40 is composed of a paper feed tray 41 on which a document is placed, a pair of side edge guides 42L and 42R for restricting the side edges of the document set on the paper feed tray 41, and a paper feed auxiliary tray 43. There is.

A sheet feeding path R1 for guiding the separated document to the platen P is formed in the separating / feeding section 50, and the sheet feeding path R1 is partitioned by guide plates 510 and 511. Then, the separating / feeding unit is arranged along the sheet feeding path R1. The kick roller 5 is provided on the entrance side of the sheet feeding path R1.
2 is provided in the paper feed tray 41 so as to be able to move back and forth, and the guide plates 510 and 511 are used to feed the paper feed roller 53 and the separation belt 5.
4 are arranged so as to enter the sheet feeding path R1 and not to be in contact with each other, and to overlap each other. Further, a registration roller 55 and a pinch roller 56 are provided facing each other on the exit side of the paper feed path R1. Paper feed path R
The outlet portion 1 is located at the point Y of the reading portion T defined on the upper surface of the platen P. A part of the paper feed path R1 is also formed by the cover means 30 as described later. At the entrance of the paper feed path R1, a document stopper 57 that is provided so as to be able to move forward and backward with respect to the guide plate 511, and a lever 58 that cooperates with the sensor S1 to detect the presence or absence of a document on the paper feed tray 41 are provided. A registration sensor S2 is provided between the paper feed roller 53 and the registration roller 55 on the paper feed path R1.

The document regulating plate 57, the kick roller 52, the paper feeding roller 53, the separation belt 54, etc. provided along the paper feeding path R1 are constructed so as to be rotated / rotated by the forward / reverse rotation of the drive motor M1. ing. That is, when the drive motor M1 is rotated in the normal direction, the separation sheet feeding section 50 has a kick roller 52.
Only the paper feed roller 53 rotates in the forward direction (original conveying direction), and the separation belt 54 rotates in the reverse feeding direction. As a result, the originals placed on the paper feed tray 31 are fed one by one to the paper feed path R.
1. Transport from the entrance to the exit. When the drive motor M1 rotates in the reverse direction, the kick roller 52 is separated from the surface of the original. The transport unit 20 includes an endless transport belt 23 and a pair of pulleys 2 that drive the transport belt 23 so as to rotate in the forward and reverse directions.
1 and 22 and a plurality of press rollers 24 that press the conveyor belt 23 against the platen P. In addition, the transport unit 20
Has a size sufficient to cover a section (between X and Y) slightly smaller than the minimum copy document size (B5 horizontal).
(See Figure 13).

The conveying belt 23 forms a document path R2 with the platen P, the entrance of the document path R2 is located at the point Y, and the exit is at the reading reference point X (Q1) defined at the front end of the reading section T. It is formed so as to be positioned substantially. A paper discharge unit 60 is provided behind the exit (reference point X) of the transport unit 20.
The paper discharge unit 60 includes an endless belt-shaped paper discharge belt 61, a pair of rollers 62 for driving the paper discharge belt 61 so as to be able to rotate forward and backward,
63, a roller 63 for transferring the drive of the conveyor belt 23 to the roller 63, and guide members 65, 66 for guiding the document discharged from the exit of the document path R2 to the discharge tray unit 70.
A discharge path R3 is formed between the guide members 65 and 66 for guiding the document sent from the transport unit 20. Further, a leaf spring member 67 having one end fixed to the guide member 65 and the other end pressing the document against the paper discharge belt 61 is provided at a position away from the facing portion of the paper discharge belt 61. It should be noted that the above-described paper discharge belt 61 to the leaf spring member
The sheet discharging unit is constituted by the constituent members of the sheet discharging unit 60 that reach the number 7.

The paper discharge tray section 70 is composed of a paper discharge tray 71, a projection member 72 extending in a direction substantially parallel to the document conveying direction, and a paper discharge auxiliary tray 73. As shown in FIGS. 4 and 6, the cover means 30 is provided below the separating / feeding unit 50 on the platen P side, and the pressure plate 31 is provided in parallel with the platen P, and the pressure plate 31 is spaced apart from the platen P by a predetermined distance. In addition, supporting members 32 and 33 that removably support the automatic document feeder 10 and elevating means 34 that moves the pressure plate 31 toward and away from the platen P are provided. An engagement fixing portion 311 that engages and fixes the pressure plate 31 with respect to the support member 32, and a pressure plate 31 that engages with the support member 33 and slides the pressure plate 31 in a direction substantially parallel to the platen P. The slide portion 312, the support members 32, 33, and the pressure plate 31 can be held by an operator in order to release the engagement / fixation between the slide member 312 and the support member 33. A large U-shaped weight portion 313 is provided.

The support member 33 is fixed to the frame of the automatic document feeder 10. The support member 32 is a connecting member 341.
Is connected to the drive shaft 342 by. The cover unit 30 has a size that covers an area of the upper surface of the platen P other than the area covered by the transport unit 20, that is, a section (between Y and Z) opposite to the reading reference point X of the reading unit T. . Here, referring to FIG. 9, the relationship between the section (XY) and the section (YZ), the amount of the slide of the pressure plate 31, the relationship with the discharge sensor S3 of the discharge unit 60, and the like are referred to. explain. First, the end of the pressure plate 31 on the side of the transport unit 20 is defined as the pressure plate end 31a,
A portion between the pressure plate end portion 31a and the conveyor belt 23, that is, a portion corresponding to the exit of the sheet feeding path R1 side is hereinafter referred to as an adjacent portion Y.

Therefore, in the present invention, the reading reference point (original setting reference point) X (Q1) is set at the discharge side end of the platen P, but the apparatus 10 is provided between the reference point X and the adjacent portion Y. The length of the small original to be processed, which is shorter than the B5 horizontal size in this example. In other words, even when the front end of the minimum size original B5 horizontal is placed at the reference point X as shown in FIG. 13, the rear end of the minimum original B5 is located below the pressure plate 31 beyond the adjacent point Y, Even with such a minimum size original, the rear end of the original is always suppressed by the pressure plate 31 during exposure, and the rear end of the original is lifted to prevent black lines from being generated due to insufficient exposure light amount to the original. There is. On the other hand, the rear end of the pressure plate 31 is made large enough to cover the maximum size original document (double letter in this example) as shown. Therefore, when the pressure plate 31 is at the position shown by the solid line in FIG. 6, it is called the first position, and what is shown by the phantom line is the second position.

On the other hand, various predetermined stop positions Q defined on the platen in the section (XY) are defined as follows. First, it has already been described that the reading reference point (original setting reference) X for setting and exposing the original on the platen P is Q1. Next, as will be described in detail later in the explanation of the operation, after the document is once fed back (switched back),
The document leading edge temporary stop position when the document is advanced to be localized at Q1 is defined as Q2. Q3 to Q5 shown in the next figure are defined as follows. These reference points Q3 to Q5 are all stop reference points at the trailing edge of the original document, and are positions that serve as a reference for the document to be conveyed in the forward direction and temporarily stopped in order to feed the rear end portion under the pressure plate 31. , Is also the starting point for switchback. Further, Q3 is the B5 horizontal document, Q4 is the A4 horizontal and letter horizontal, and Q5 is the document trailing end stop reference position above the above. Then, when the trailing ends of the originals of each size reach the above-mentioned stop reference points Q3 to Q5, the discharge sensor S3 is located at a position where the leading ends of the originals of all sizes can be detected.
The installation position of is decided.

Next, the drive system for the transport section 20 and the cover means 30 will be described with reference to FIG. The output shaft 96 of the drive motor M2 is provided with an interrupter 971 having slits formed in a disk at equal intervals. From a photo sensor S4 that generates a pulse in response to light passing through the slit of the rotating interrupter 971. The pulse generating means 97 is provided. Conveyor belt 23 forming the document path R2
Means the belt drive transmission means 9 for transmitting power from the drive motor M2.
By rotating the drive pulley 21 via the shafts 50, 951, the shaft 952, and the gears G8, G9, and G10, the drive pulley 21 is driven in the forward direction (document conveying direction) and the backward feeding direction. Further, the rolling roller 64 provided above the driven pulley 22 of the transport belt 23 is directly transmitted with the driving force from the surface of the transport belt 23, and the discharge belt 61 has the same peripheral speed as the transport belt 23. It is driven in the same document transport direction. The registration roller 55 is fixed to the shaft 952, and is driven in the same document conveyance direction at the same peripheral speed as the conveyance belt 23.

That is, the registration roller 55, the drive side pulley 21, and the paper discharge belt 61 are rotated together by a unified driving means (drive motor M2), and the registration roller 55 has the same speed as the original fed through the paper feeding path R1. In order to convey the document path R2 and the paper discharge path R3, they rotate while maintaining substantially the same peripheral surface speed. That is, the document conveyed in each of the passages R1, R2, and R3 moves at a constant speed regardless of the forward and reverse directions. The rotary drive system can be controlled based on the pulse signal of the pulse generating means 97. On the other hand, the driving force is transmitted to the drive shaft 342 via the shaft 952, the gears G11, G12, G13 and the like. The drive shaft 342 is gear-connected so as to rotate in the same direction as the pulley 21 that drives the transport belt 23, and slides the pressure plate 31 in the same direction as the forward and reverse transport directions of the transport belt 23. Conveyor belt 2
3 is driven in the forward direction (original feeding direction), the drive shaft 3
The forward rotation of 42 holds the pressure plate 31 at the solid line position in FIG. 6, that is, at the first position close to the platen P. Axis 9
The torque limiter incorporated in 52 is used to press the pressure plate 31.
Is held at the position shown by the solid line in FIG. 6 with a constant force. When the transport belt 23 is driven in the reverse feeding direction, the pressure plate 31 is moved to the position indicated by the chain line in FIG. 6, that is, the platen P by the reverse rotation of the drive shaft 342.
The torque plate is held at a second position away from the pressure plate 31 and is held by the torque limiter incorporated in the shaft 342 at a constant force at the position indicated by a chain line (phantom line) in FIG.

The hinge portion 80 shown in FIGS. 1 and 3 is composed of a spring-equipped hinge 81 for supporting the automatic document feeder 10 on the upper surface of the copying machine M so as to be openable and closable, and a springless hinge 82.

Next, the operation will be described with reference to the above-mentioned drawings and the flow charts shown in FIGS. 7 and 8 and the operation explanatory diagrams of FIGS. 9 to 19. As shown in FIG. 10, an original document D is set on a paper feed tray 41 prior to copying, and when an original document set signal is given to the copying machine M, the original document feeding output from the copying machine M switched to the automatic original document feeding mode is performed. Upon receiving the signal, the empty sensor S1 confirms the presence of the document D (steps ST1 to ST3), the drive motor M1 rotates normally, the document regulation plate 57 retracts below the guide plate 511, and the kick roller 52 Rotates and descends to come into contact with the document D on the paper feed tray 41. As a result, the document D is sent forward, enters between the paper feed roller 53 and the separation belt 54, and is rotated by the paper feed roller 53 rotating in the transport direction.
Moves forward. At this time, a plurality of documents D are placed on the paper feed tray 41.
When a plurality of originals are simultaneously fed by the kick roller 52, the lower original that contacts the separating belt 54 is prevented from advancing by the separating belt 54 that rotates in the reverse feeding direction. Therefore, only one original is allowed to pass forward by the paper feed roller 53 (ST4,
5). Note that the cover unit 30 is also localized at the first position along with various initialization operations according to the start command (ST2).

FIG. 10 shows the sizes of various originals and the original regulating plate 57 when these are placed on the paper feed tray 41.
The protruding state from is shown. According to this, in the present embodiment, the paper feed auxiliary tray 43 is provided for the legal size or larger.
You can see that you need to withdraw. In this way, the original D sent out is registered in the registration sensor S2 as shown in FIG.
After the leading edge is detected by the roller 5, the roller 5 comes into contact with the registration roller 55 and the pinch roller 56 in a stopped state, and after a predetermined time has passed (the built-in timer is up) from the leading edge of the document D, the roller 5
By stopping the belts 2, 53 and the belt 54, the document D is somewhat bent, the leading end is uniformly pressed against the tangent portion of the registration roller 55 and the pinch roller 56, and the leading end becomes parallel and the skew is corrected (ST6, 7). Then, the drive motor M1 is stopped and the reverse rotation (ST8) is performed at the same time as the drive motor M1.
2 is rotated in the normal direction (ST9), and the document D conveyed by the registration roller 55 through the sheet feeding path R1 is guided to the adjacent portion Y of the platen P and is driven by the same drive motor M2 in synchronization with the registration roller 55. It is sent forward along the document path R2 together with the conveyor belt 23. Then, the trailing edge of the document is detected by the sensor S2 (S2 sensor OFF, other built-in timer is up), and the document size is detected and stored (ST10, 11). At the same time, the pulse count by the pulse generating means 97 is triggered, and a predetermined count based on the document size information is counted (ST12).

The above is the same as the following embodiments, and each embodiment will be described below separately for each control. In the case of setting an original using the original size signal from the sensor S2, as shown in FIG. 12, when the predetermined number is counted, the rear end of the original has predetermined stop positions Q3, Q depending on the size.
After stopping at either Q4 or Q5, M2 immediately rotates in the reverse direction and the document is fed in the reverse direction (ST13, 14). Note that FIG.
(A) and (B) show the stopped state of each size original. At this time, the leading ends of all the originals handled by this automatic document feeder are in the state where the trailing ends of the originals reach the platen. At the same time, the stop positions Q3, Q4, and Q5 are set in advance so that the sensor S3 passes through the sensor S3 at the same time.
At the same time that the document D is subjected to the backward feeding action by the reverse rotation of the drive motor M2, the drive shaft 342 of the pressure plate 31 is also rotated in the counterclockwise direction in FIG. 6, and the pressure plate 31 is indicated by the first solid line. Instantly shifts from the position of to the second position indicated by the imaginary line (ST15). The drive motor M2 continues the reverse conveyance as it is, the rear end of the document D moves to the right in FIG. 6 under the pressure plate 31, and M2 is stopped by the pulse counting based on the size information (ST16,
17) (see Figure 12). At this time, the leading edge of the document is at the document leading edge temporary stop position Q2. Then, M2 again rotates the equivalent of the predetermined pulse to the reading reference point Q1 (X) and localizes (ST18 to 20). The information about the M2 motor stop is transmitted to the main body device, where the exposure process is performed (see FIG. 14).
At the same time as the completion of exposure, M2 starts to rotate in the normal direction again, and the document is ejected (ST21, 22, 23). Then, the first-out original is verified (ST24), and if there is a first-out original, S
While returning to T9 and repeating the above operation, the processed original document is directly discharged to the paper discharge tray unit 70 through the paper discharge unit 60 (see FIG. 15).

Next, a second embodiment, which is a modification of the control method of the first embodiment, will be described. In FIG. 17, the B5 side is excluded from the conveyance specification of the automatic document feeder, and the operation itself is completely the same as that of the first embodiment, but as shown in FIG. 17B, the rear end of the document D is moved to the lower side of the pressure plate 31. The insertion amount is large, and the lifting of the rear end portion of the document D from the platen surface can be reliably regulated by the pressure plate 31, and image unevenness can be prevented.

In the case of setting an original without using the original size signal from the sensor S2 In the first third embodiment, the control of the first embodiment is the same as that of step ST13 in the flowcharts of FIGS. Is the same. Then, after ST13, the process proceeds to that of FIG. That is, since the automatic document apparatus 10 does not use the document size signal, it is not possible to selectively control the trailing edge of the document with respect to the stop positions Q3 to Q5 according to the size thereof, as in the above embodiment. The stop reference position is set in advance at a position Q3 at which the leading edge of the document always passes (ON) the discharge sensor S3, and steps ST40, ST41
In S, after the S3 is turned ON, the rear end comes to any of Q3 to Q5, M2 is stopped, and then the motor is reversed, and the front end passes S3 again (S3 OFF) to trigger the pulse counter (ST42). Then, M2 is stopped when a pulse corresponding to the temporary stop reference Q2 has passed from the sensor S3 (ST44), and the subsequent steps are the same as the above-described flow of the first embodiment, so that the process proceeds. According to this embodiment, since the backward feeding (switchback) operation of the document serves as the reference of the leading edge of the document and is controlled by the pulse number of the short distance between the paper discharge sensor S3 and the reference point Q2,
If the deviation between the number of pulses and the actual carry amount is small, the position can be detected accurately, and the cover means can be operated by a solenoid or the like regardless of the operation of the drive motor M2, Q2
It is possible to directly switch back to Q1 without having to adjust the position by forward rotation again, which contributes to shortening the processing time. In this case, the process proceeds from ST44.

Next, a fourth embodiment of the invention will be described with reference to FIG. In this embodiment, as in the third embodiment, the trailing edge document stop position for the switchback operation is unified to Q3 for the B5 side of Embodiment 1, regardless of the size, and the size of the transport unit 23 is large. In this case, the document trailing end stop reference point Q3 is brought to a position corresponding to the adjacent portion Y. Since the transport unit 20 is downsized, the cover unit 3 is provided.
0 is getting bigger. Therefore, this control is based on the third
It can be similar to that of the embodiment. Considering the fact that the size of documents to be processed on a daily basis is often concentrated on B5, A4, etc., such a configuration is cheaper and easier to handle. Although various embodiments of the present invention have been described above, the embodiments of the present invention are not of course limited to the configurations and operations of the above-described embodiments, and any modifications within a range not departing from the gist of the present invention are applicable to the present invention. It is included.

Next, some modifications will be illustrated. (1) In the above embodiment, the cover means is driven by the conveying means and the unitary driving means, and is configured to move between the first position and the second position by forward / reverse rotation of the driving means. However, it is also possible to separate the cover means from the conveying means and to drive them by an independent drive means such as a solenoid. (2) The cover means may be a fixed type having a minute gap with respect to the platen surface.

[0032]

In the automatic document feeder according to the present invention, the cover means is provided at a position for restricting the lifting of the trailing end portion of all the documents set at the image processing position on the platen into the platen for taking in the platen. , After the trailing edge of the original reaches the platen, the original is fed back and a part of the original is inserted between the cover means and the platen so that the original is set to the image processing position on the platen. , The rear end of all size originals is pressed by the cover means, and the rear end of the conventional original is lifted from the platen surface and the exposure light amount becomes insufficient,
As a result, quality defects such as black line generation have disappeared. In addition, a document set reference point is provided at the end of the platen on the side where the document is discharged, and any size document that is taken in from an adjacent part has its rear end introduced at a predetermined stop position on the platen. A sensor means for detecting the front end of the original is provided at an appropriate position of the discharge section through which the front end of the original passes, and the conveying means is fed backward after the rear end of the original reaches the platen. When the leading end of the document passes through the sensor means again, the conveyance amount of the conveying unit is controlled, and the control unit for setting the leading end of the document to the set reference position on the platen is guided to the set reference position. The movement detection distance of the original is greatly shortened,
For this reason, the positioning accuracy of the document has been dramatically improved.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment in which an automatic document feeder according to the present invention is applied to a copying machine.

FIG. 2 is a top perspective view of the same document feeder as above.

FIG. 3 is a perspective view showing an embodiment in which the automatic document feeder of the present invention is applied to a copying machine with a platen released.

FIG. 4 is a side sectional view of the same document feeder as above.

FIG. 5 is a plan view of the same document feeder as above.

FIG. 6 is a side view illustrating the outline of a platen cover portion.

FIG. 7 is a flowchart A of operation.

FIG. 8 is a flowchart B of the operation.

9A and 9B are a side view and a document conveyance state explanatory view showing a first embodiment of the present application using a document size signal.

FIG. 10 is an explanatory diagram showing a state in which a document according to the first embodiment is set on a paper feed tray.

FIG. 11 is an explanatory diagram of a functional operation of the registration sensor S2 in the first embodiment.

FIG. 12 is an explanatory diagram of a state in which the document is stopped at the trailing end stop reference position in the first embodiment.

FIG. 13 is an explanatory diagram when the leading edge of the switched back document is at the temporary stop reference point Q2 in the first embodiment.

FIG. 14 is a reading reference point Q1 for a document in the first embodiment.
It is a state explanatory view when it is set to (X).

FIG. 15 is an explanatory diagram during an exposure operation in the first embodiment.

FIG. 16 is an explanatory diagram of a switchback localization state of a preceding document discharged from the preceding document in the first embodiment.

FIG. 17 is an explanatory diagram of a second embodiment of the present invention, which is a modification of the first embodiment.

FIG. 18 is an explanatory diagram of a third embodiment of the present invention that does not utilize a document size signal.

FIG. 19 is an explanatory view of a fourth embodiment of the present invention which is a modification of the third embodiment.

[Explanation of symbols]

 M copy machine (image processing apparatus) P platen 10 automatic document feeder (first, second, and third embodiments) 20 transport unit (transport unit) 30 cover unit 60 sheet discharge unit (discharge unit) X (Q1) read reference point (Document Setting Criteria) Y Adjacent part Q1, Q2, Q3 Predetermined stop position of document rear end on platen 100 Automatic document feeder (fourth embodiment) 101 Conveying unit (conveying means) 102 Covering means

Claims (7)

[Claims] 1. An image processing apparatus comprising: a platen which covers a part of a platen and which conveys a document on the platen; and a cover which is adjacent to the platen and covers the other part of the platen. , The document which is taken in between the transporting means and the cover means and discharged from the other end of the transporting means is made to enter a part of the original document into the lower part of the cover means by the reverse transporting of the transporting means, and the platen In an automatic document feeder that sets a document at an upper image processing position, after the trailing edge of the document reaches the platen, the document is fed back to partially cover the document between the cover means and the platen. The original is set at the image processing position on the platen by inserting it between the two, and at the same time, all the originals set at the image processing position on the platen are taken into the platen and the rising of the trailing end portion in the conveying direction is regulated. Providing the said cover means to a position automatic document feeder according to claim. 2. The automatic document feeder according to claim 1, wherein the cover means is fixed to the platen surface at a position having a gap into which a document can be inserted, or is supported so as to be slidable or vertically movable. 3. The automatic document feeder according to claim 1, wherein the leading end of the document is detected at a position where the trailing end of the document taken into the platen is introduced onto the platen. With the provision of the sensor means, after the trailing edge of the document reaches the platen, the transporting means is transported backward, and the transport amount of the transporting means is controlled from the time when the sensor means detects the leading edge of the document again, An automatic document feeder, comprising control means for setting the leading end of the document at an image processing position on a platen. 4. The automatic document feeder according to claim 1, further comprising a document size detecting means for detecting a size of a document captured on a platen, and a leading end portion of the document in a loading direction sets at least the leading end portion. The trailing end stop reference position of the original is set to a position beyond the set reference position on the platen, and the trailing end of the original is set to the trailing end stop reference position on the platen according to the size information of the original size detecting means. An automatic document feeder, further comprising control means for setting the original document at a set reference position on the platen by the reverse conveyance of the conveying means after the original document is conveyed. 5. The automatic apparatus according to claim 4, wherein the trailing edge stop reference position is set at the same point on the platen where the trailing edge portions of the originals of all sizes taken in by the conveying means stop. Document feeder. 6. A plurality of trailing end stop reference positions according to a stop position on the platen of the trailing end of the original at a position where the leading end of the original taken in by the conveying means exceeds a set reference position on the platen by a predetermined distance. It has been set, 4.
The automatic document feeder described in. 7. The automatic document feeder according to claim 1, wherein a document size detecting means for detecting a size of a document taken in on the platen, and a rear end portion of the document taken in on the platen are introduced on the platen. In this state, the sensor means is provided at a position where the leading edge of the original can be detected, and the leading edge of the original in the fetching direction of the original exceeds at least the set reference position on the platen for setting the leading edge of the original. The trailing edge stop reference position is set, and after the trailing edge of the document reaches the platen, the transporting means is fed back, and the transport amount of the transporting means from the time when the leading edge of the document passes the sensor means again. Control means for setting the leading edge of the document at the set reference position on the platen, and the trailing edge of the document according to the size information of the document size detecting means. Automatic document feeding, further comprising: second control means for setting the original document to the set reference position on the platen after being conveyed to the rear end stop reference position on the platen by the reverse conveyance of the conveying means. apparatus.