JPH10148976A - Automatic document feeder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an automatic document feeder capable of obtaining many kinds of discrimination available document sizes, with a simple constitution by eliminating a cause of variance in a read value in a document size, and properly discriminating the document size by suppressing the variations in the read value in the document size due to the slip and deflection of a document during carrying. SOLUTION: In the automatic document feeder 100, a controller 50 is provided with a pulse generating part 50a for outputting pulse signals, in synchronization with the operation of a motor for carrying the document, a pulse counter 50b for counting the pulse signals, based on detection signals from document size detecting sensors 40a and 40b provided to be away from each of other on the upstream and downstream sides of a carrying path and a document size discriminating part 50c for executing the correction processing of a count value obtained by counting with a prescribed pulse counting procedure, to discriminate the document size.

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 applied to an image processing apparatus such as a copying machine, a facsimile machine, a scanner, and the like. The present invention relates to an automatic document feeder that can be used.

[0002]

2. Description of the Related Art Conventionally, in an image processing apparatus such as a copying machine, a facsimile apparatus, a scanner apparatus, etc., originals are separated one by one from an original bundle placed on an original placing table and conveyed to an image processing position. After performing image processing such as reading image data, the document is carried out to a paper output tray.

As a method of detecting the size of a document in a conventional automatic document feeder of this type, for example, a width guide and a rear end of a document are brought into contact with a document guide such as a side guide and a back guide provided on a document table. A method of detecting a document guide position based on the document size and determining the document size by comparing it with a standard size such as A3, B4, A4, etc. is known. The selection conditions and the conditions for changing the paper size are set.

In Japanese Patent Application Laid-Open No. 1-163762, an indicating lever and a potentiometer are provided along a guide on a document glass surface of a copying machine, and the position of the indicating lever corresponding to the original is read by the potentiometer. A method for determining a document size is described. Further, as another detection method, the leading edge and the trailing edge of the document are detected by one document detection sensor provided on the document transport path, and the number of rotation pulses of the paper feed motor is counted while the sensor is detecting the document. Thus, the length of the document in the transport direction is detected, and the size of the document (for example, A4, B4,
3,...) Is also known.

[0005]

However, in the method of detecting the positions of the guide and the instruction lever corresponding to the width and rear end positions of the original, there are many components for detecting the original size, and the mechanism is complicated. In addition, there is a problem that the adjustment work for the size detection is complicated because the adjustment work of the guide and the lever by the operator is required. In addition, since the dispersion of the read values increases due to the degree of adjustment of the guide and the lever, the determination range of the document size must be set large in advance, and the types of the document sizes that can be determined are limited to, for example, only the standard size. There was a problem. Furthermore, in the method of detecting the document size by one document detection sensor in the conveyance path, the reading value of the length in the conveyance direction of the document becomes large due to slipping or bending of the document during document conveyance, and an appropriate There was a problem that the size could not be determined.

The present invention solves the above-described problems, eliminates factors that cause variations in the document size reading value, and has many types of document sizes that can be determined with a simple configuration.
It is another object of the present invention to provide an automatic document feeder capable of suppressing a variation in a document size read value due to a slip or a bend of a document being conveyed and performing an appropriate document size determination.

[0007]

According to the first aspect of the present invention,
In order to solve the above-mentioned problems, a document transport means for transporting a document on a predetermined transport path, and a first document provided at a predetermined position in the transport path and detecting the document transported by the document transport means Detecting means, second document detecting means provided in the transport path behind the first document detecting means in the transport direction, and driving means for driving the document transport means. Pulse generating means for synchronously outputting a predetermined pulse signal; pulse number counting means for counting pulse signals output from the pulse generating means based on detection signals from the first and second document detecting means; A predetermined correction process is performed on the number of pulses counted by the pulse number counting means to control the document size determining means for determining the size of the document and the counting start and end operations of the pulse number counting means. Together, it is characterized in that a control means for controlling the operation processing according to the pulse number correction processing of the document size determination means.

According to the configuration of the automatic document feeder according to the first aspect, the counting start and end operations of the pulse number counting means by the two document detection sensors on the upstream side and the downstream side which are also installed in the conventional apparatus. Is controlled and the document size is determined based on the count value during the period when the document is detected by the two document detection sensors. Therefore, a configuration such as a document guide and a potentiometer for directly detecting the document size is required. And not. In addition, since the document is detected by the two document detection sensors and the count value counted by the pulse counter is corrected to calculate a pulse value corresponding to the length of the document in the transport direction,
It is possible to appropriately determine the document size by suppressing variations and errors in read values caused by a document conveyance slip or deflection.

According to a second aspect of the present invention, in the automatic document feeder according to the first aspect, the control means is arranged such that the pulse number counting means detects the leading end of the original by the first original detection means. Counting at the time when
The document detecting means controls the counting to end when the trailing edge of the document is detected, and the document size determining means determines the first and second counts from the number of pulses counted by the pulse number counting means. The number of pulses corresponding to the separation distance of the original detection means is controlled to be subtracted.

According to the second aspect of the present invention, the leading edge of the document is detected by the document detection sensor disposed on the upstream side of the document conveying path, and pulse counting is started.
From the count value obtained by stopping the pulse count by detecting the trailing end of the document by the document detection sensor arranged on the downstream side, subtracting the number of pulses corresponding to the separation distance between the document detection sensors, The number of pulses corresponding to the length of the document in the transport direction is calculated, and the size of the document can be determined in comparison with the paper size, thereby suppressing variations and errors in the count value due to slippage and deflection during document transport. Thus, an appropriate document size can be determined.

[0011] Further, the invention according to claim 3 is based on claim 1.
In the automatic document feeder described above, the control means starts counting when the pulse number counting means detects the leading edge of the document by the second document detection means, and the first document detection means At the time when the trailing edge of the document is detected, control is performed so as to end the counting, and the document size determination means sets the number of pulses counted by the pulse number counting means to the number of pulses counted by the first and second document detection means. It is characterized in that control is performed so that the number of pulses corresponding to the separation distance is added.

According to the third aspect of the present invention, the leading edge of the document is detected by a document detection sensor disposed downstream of the document conveying path, and pulse counting is started.
From the count value obtained by detecting the trailing end of the document by the document detection sensor arranged on the upstream side and stopping the pulse count, the pulse number corresponding to the separation distance between the document detection sensors is subtracted, Since the number of pulses corresponding to the length of the original in the transport direction can be calculated and the original size can be determined in comparison with the paper size, the period counted by the pulse counter is shorter than that of the second embodiment. In addition, it is possible to suppress errors due to counting of pulse signals, and variations and errors in count values due to slips and deflections during document conveyance, so that a more appropriate document size can be determined.

The invention according to claim 4 is the first invention.
In the automatic document feeder described above, the control means starts counting when the pulse number counting means detects the leading edge of the document by the first document detecting means, and the trailing edge of the document is detected. At the time when the counting is completed and the first pulse number is obtained, counting is started when the leading edge of the document is detected by the second document detecting means. At the time of detection, control is performed so as to end counting and obtain a second pulse number, and the document size determining means averages the first and second pulse numbers counted by the pulse number counting means. It is characterized in that it is controlled so that

According to the fourth aspect of the invention, each of the document detection sensors on the upstream and downstream sides of the document conveyance path detects the leading and trailing edges of the document and counts two count values. By comparing and averaging the count values, the number of pulses corresponding to the length of the original in the transport direction is calculated, and the size of the original can be determined in comparison with the paper size. The two types of count values can be used for the determination of the document size, and variations and errors in the count values due to slippage and deflection during document conveyance can be reduced as compared with a case where the sensors are detected by one sensor. A more appropriate document size can be determined.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An automatic document feeder according to the present invention will be described below with reference to embodiments. First, the basic configuration of the automatic document feeder according to the present invention will be described with reference to FIG. In FIG. 1, reference numeral 100 denotes an automatic document feeder, and reference numeral 10 denotes a sheet feed / separation roller group driven by a sheet feed motor 10m, and feeds documents one by one from a document bundle placed on a document table. A paper feeding section for feeding paper, 20 has a transport roller group or a transport belt driven by a transport motor 20m, and a transport section for transporting the fed document to a predetermined image processing section or the like, and 30 is driven by a discharge motor 30m. This is a paper discharge unit that has a paper discharge roller group that carries out documents and carries out a document to a paper discharge tray. Here, the sheet feeding unit 10, the conveying unit 20, and the sheet discharging unit 30 correspond to a document conveying unit, and the sheet feeding motor 10m, the conveying motor 20m, and the sheet discharging motor 30m correspond to a driving unit. Document detection sensors (first and second document detection means) 40a and 40b detect the leading edge and the trailing edge of the conveyed document to detect the presence / absence of the document, the conveyance position, and the like.
For example, they are provided on the upstream side and the downstream side of the transport path of the paper feeding unit 10 so as to be separated from each other. Reference numeral 50 denotes a controller (control means) for controlling the components of the automatic document feeder 100, and a pulse generator (pulse generator) for outputting a pulse signal in synchronization with the operation of a motor for feeding the original. 50a, a pulse counter (pulse counting means) 50b for counting the pulse signals output from the pulse generator 50a based on the detection signals from the document detection sensors 40a and 40b, A document size determination unit (document size determination unit) 50c that corrects the count value and compares and compares a preset paper size with a document size is provided. Here, as the pulse signal counted by the pulse counter 50b, for example, in a configuration using a stepping motor as a motor as a driving means, a motor driving pulse may be used, or a DC motor (DC motor) may be used. )
In the case where is used as the driving means, an output signal from an encoder for detecting the rotation of the motor may be used. Reference numeral 60 denotes an operation unit including an operation panel for operating a document conveyance operation and the like and a liquid crystal display panel for displaying information to an operator. 70 denotes an image processing apparatus (copier, facsimile, etc.) to which the automatic document conveyance device 100 is applied. Device, a scanner device, etc.).

Next, a schematic configuration of an image processing apparatus to which the automatic document feeder according to the present invention can be applied will be described with reference to FIG. In this embodiment, a case is shown in which the present invention is applied to a copying machine as an image processing apparatus. In FIG. 2, 1
Is a copying machine having a double-sided copying function as an image processing apparatus, and a contact glass 1a is provided on an upper surface of the copying machine 1. An automatic document feeder 100 is provided above the copying machine 1. The automatic document feeder 100 is connected to the copy machine 1 via a hinge (not shown) so as to open and close the contact glass 1a. .

The automatic document feeder 100 includes a document tray 10a as a document mounting table on which a document bundle 80 including a plurality of documents can be placed, and one document from the document bundle 80 placed on the document tray 10a. A sheet feeding unit 10 provided with a separation and sheet feeding roller group for separating the sheet and feeding it toward the contact glass 1a;
a, and conveys and stops the original to the original reading position on the contact glass 1a, and an image reading unit (a known exposure lamp, mirror, lens, and the like) of the copying machine 1 disposed below the contact glass 1a. , A CCD, etc.), and a transport unit 2 including a transport roller group and a transport belt for transporting the original that has been read by the contact glass 1a.
0, the document delivered from the document reading position of the contact glass 1a by the transport unit 20 is ejected to the side of the copying machine 1 according to the copy mode. A paper discharge unit 3 provided with a reverse and paper discharge roller group for discharging paper to one of the paper trays 30b
0.

Each of the components will be described in more detail. The paper feed section 10 is composed of a call roller 10b, a paper feed roller 10c, a reverse roller 10d, a pull-out drive roller 10e, a pull-out driven roller 10f, and original detection sensors 40a and 40b. I have. These call rollers 10b and paper feed rollers 10
c, a reverse roller 10d, and a pull-out drive roller 10e are driven by a paper feed motor 10m.
0 m via a drive system such as a gear mechanism. As shown in the basic configuration of FIG. 1, the sheet feeding motor 10m is driven by a control signal from the controller 50, and the controller 50
When a paper feed start signal is input from the
m is driven forward and reverse.

When the paper feed motor 10m is driven to rotate forward, the recall roller 10b rotates clockwise to feed the uppermost original from the original bundle 80, and to feed the original feed roller 1b.
0c and the reverse roller 10d are rotated clockwise, and only the top document is separated from the document bundle 80. The separated document is provided with a pull-out driving roller 10e rotating counterclockwise and a pull-out driven roller 10f rotating therewith.
And is pulled out from the paper feed roller 10c and the reverse roller 10d, and is conveyed toward the contact glass 1a. When the leading edge of the document is detected by the document detection sensor 40b disposed downstream of the pull-out driving roller 10e and the pull-out driven roller 10f, the controller 50 drives the sheet feeding motor 10m in reverse rotation based on the output signal from the document detection sensor 40b. Let it. At this time, the feed motor 10m
Roller 10b, paper feed roller 10c, reverse roller 1
The callout roller 10b and the paper feed roller 10c are stopped by the drive system interposed between 0d and the pullout drive roller 10e, the pullout drive roller 10e is continuously rotated counterclockwise, and the reverse roller 10d is rotated clockwise. , The following documents are prevented from entering the nip portion of the paper feed roller 10c and the reverse roller 10d so as not to be separated. Meanwhile, separate first,
The conveyed document is fed from the paper feeding unit 10 to the conveying unit 20 by a pull-out driving roller 10e and a pull-out driven roller 10f.
Transported to

The transport section 20 includes a transport belt 20a, transport belt driving rollers 20b and transport belt driven rollers 20c provided at both ends of the transport belt 20a, and a transport belt 20a. And a plurality of pressure rollers 20c for pressing the contact glass 1a. The transport belt driving roller 20b is driven by a transport motor 20m. When the leading edge of the document is detected by the document detection sensor 40b as described above, the controller 5
By carrying out the forward rotation based on the signal from 0, the transport belt 20a is driven via the transport belt drive roller 20b to transport the document onto the contact glass 1a.

When the document conveyed from the paper supply unit 10 is conveyed onto the contact glass 1a by the conveyance belt 20a and the rear end of the document is detected by the document detection sensor 40b, the controller 50 starts the conveyance motor from this detection point. The rotation pulse of 20 m is counted, and when the rotation pulse reaches a predetermined value, the driving of the conveyance belt driving roller 20b is stopped to stop the conveyance belt 20a, thereby moving the document to the document reading position on the contact glass 1a. Stop. When the original stops at the original reading position on the contact glass 1a, the copying machine 1 reads and exposes the original. When the reading and the exposure are completed, a signal is input from the copying machine 1 to the controller 50, the transport motor 20m is driven to rotate forward, and the original is carried out of the contact glass 1a to the paper discharge unit 30 by the transport belt 20a.

On the other hand, when the trailing end of the original is detected by the original detection sensor 40b, or when the paper supply motor 10m and the conveyance motor 20m are stopped, the controller 50 drives the paper supply motor 10m again, and (The next original) is separated and fed as described above. The feed from the time when the leading edge of the next original is detected by the original detection sensor 40a disposed downstream of the paper feed roller 10c and the reverse roller 10b (pull-out driving roller 10e and pull-out driven roller 10f, or upstream of the original detection sensor 40b). The rotation pulse of the paper motor 10m is counted, and when the rotation pulse reaches a predetermined value, the driving of the recall roller 10b, the paper supply roller 10c, and the reverse roller 10b is stopped to finish the advance operation of the original, and the paper supply unit The next document is stopped at a predetermined position 10 and is made to stand by.

The paper discharge section 30 includes a reverse drive roller 30c, a paper discharge driven roller 30d, a reverse guide roller 30e, a reverse driven roller 30f, a first switching claw 30g, a second switching claw 30h, a paper discharge driving roller 30i, and a paper discharge. Driven roller 30j, reversing sensor 40c
And 40d, and the reversing drive roller 30c, the reversal guide roller 30e, and the discharge drive roller 30f
0 m.

In the one-sided mode in which the one-sided document is conveyed, the controller 50 causes the first switching claw 30g to stand by at a position (home position) where the contact glass 1a and the first sheet discharge tray 30a communicate with each other, thereby reading the document. After the end of the exposure, the transport motor 20m is driven at the same time as the transport motor 20m is driven, and the document sandwiched by the reversing drive roller 30c and the discharge driven roller 30d is linearly discharged to the discharge tray 30a. On the other hand, the controller 5
0 is the first switching claw 30g when the duplex mode is designated.
Is moved from the home position to a position communicating with the reversing path from the contact glass 1a to the reversing drive roller 30c and the reversing guide roller 30e, so that the conveyance motor 20m is read after the reading of one side of the double-sided document and the exposure are completed.
At the same time, the paper discharge motor 30m is driven to convey the document to the reverse path. Further, when the controller 50 is in the double-sided mode in which the double-sided document is conveyed, the second switching claw 30h
Is placed in a position (home position) communicating with the return path from the reverse path to the contact glass 1a (home position), so that the original is turned upside down and the reverse drive roller 3 is turned over.
0c and the reversing driven roller 30f to be returned to the contact glass 1a. In the reversing operation, when the leading edge of the document is detected by the reversing sensor 40d provided on the reversing path, the controller 50 controls the conveying motor 20m.
Is rotated in the reverse direction to drive the transport belt 16 in the reverse direction. When the rotation pulse of the transport motor 20m from this point reaches a predetermined value, it is determined that the original has been transported to the original reading position on the contact glass 1a and transported. The motor 20m is stopped.

When reading and exposure of the back side image of the original at the original reading position are completed, a signal is input from the copier 1 to the controller 50 to drive the transport motor 20m to rotate forward and to operate the first switching claw 30g. The reversing path is communicated with the contact glass 1a, and the reversing path is communicated with the paper discharge tray 30b by the second switching claw 30h. The paper discharge tray 3 is driven via the driving roller 30i and the paper discharge driven roller 30j.
0b.

In the image processing apparatus having such a configuration,
Separation of paper feed unit 10, paper feed roller group (10b to 10f)
Corresponds to the document conveying means, and the document detection sensors 40a and 40
Each of Ob corresponds to first and second document detection means, and both configurations are existing in an image processing apparatus to which the present invention is applied. Next, a pulse counting operation and a document size determination process of the automatic document feeder applied to the above-described image processing apparatus will be described.

FIG. 3 is a flowchart showing the pulse counting operation of the automatic document feeder according to the second aspect. Note that the pulse counting operation may be performed in the pulse counter 50b or may be controlled by the controller 50. When the document bundle 80 is set on the document tray 10a and the controller 50 receives a document conveyance start signal such as the start of copying from the operation panel, the sheet feeding motor 10m is driven and the pulse counting operation is started in the following procedure. .

The size flag for judging whether or not the detection of the length of the document in the transport direction is completed is set to "1" when the detection of the length in the transport direction is completed, and when the size detection is not completed. , "0". The count flag that determines whether or not the count operation has started is set to “1” when the count operation has started, and is set to “0” when the count operation has ended. When a new document reading operation is instructed, the size flag is set to “0” and the count flag is set to “0”.

When document conveyance is started, these flags
It is determined whether or not is reset ("0")
(S1, S2). Next, the call roller 10b and the paper feed roller 1
Original document separated and conveyed by 0c and reverse roller 10d
Of document is upstream (or upstream sensor) 40a.
Is detected and turned on (S3), the pulse counter
50b count value (P_CNT) Is cleared (= 0) and
The run flag is set to "1" (S4), and the feed motor
The output from the pulse generator 50a is synchronized with the operation of 10m.
The counting of the pulse signals to be started is started (S5). Manuscripts in order
The document is conveyed in the direction of the conveyance section 20 and is a downstream document detection sensor.
(Downstream sensor) The trailing edge of the document is detected by 40b and OF
In the F state (S6), the count flag is reset.
("0") to stop the counting operation of the pulse counter 50b.
Stop (S7). The count value thus counted
(P_CNT), The upstream sensor 40a and the
Of pulses corresponding to the installation distance between the sensor and the downstream sensor 40b
(P₀) Is subtracted, and the length of the document in the transport direction is
Number of pulses equivalent to the length (number of pulses equivalent to the length: P_L= P_CNT
−P ₀) Is calculated (S8), and the size flag is calculated.
Is set to “1” and the pulse count operation is completed (S
9).

FIG. 4 is a flowchart showing a document size determination process executed by the document size determination unit 50c of the automatic document feeder according to the first, second, third, or fourth aspect.
First, in the document size determination processing, it is determined whether the size flag is set to "1" (S11). Since the number of pulses (P _L ) corresponding to the length is calculated by the above-described pulse counting operation and the size flag is set to “1”, the determination of the document size is performed by the next-stage comparison processing. Specifically, the number of size determination pulses (P
_S ) and the number of pulses corresponding to the length (P _L ) are sequentially compared to determine the corresponding size. For example, since the size of the B5 size paper is 257 × 182 mm, the B5 size is 182 mm. 66 pulses are set as the number of pulses for comparing and judging A. The size of the A4 size is 297 × 210.
mm, 78 pulses for A4 horizontal, 1 for A4 vertical
12 pulses are set, and the size of B4 size is 35
Since it is 4 × 250 mm in width, the number of size determination pulses (P _S ) is set in advance, such as 136 pulses in B4 length. Then, the number of length-equivalent pulses (P _L ) obtained by the pulse counting operation is converted to the size determination pulse number (P _S = 6).
6, 78, 112, and 136), and if the number of pulses corresponding to the length (P _L ) is less than 66 (S12), the document is determined to be a B5-size document, and the size data flag B5F is set to “
1 "is set (S17), and the B5 size is designated as the copy sheet. Then, the number of pulses corresponding to the length (P _L ) is 78.
If it is less than (S13), it is determined that the A4 size is the horizontal size, the flag A4YF is set to "1" (S18), the paper for the A4 size is used, and the pulse number (P _L ) corresponding to the length is set. 11
If it is less than 2 (S14), it is determined that the A4 size is the vertical size, the flag A4TF is set to "1" (S19), the A4 size portrait paper is designated, and the number of pulses corresponding to the length (PL ₎ ) Is less than 136 (S15), the size is determined to be the B4 vertical size, and the flag B4F is set to “1” (S2).
0), B4 size paper is specified. If the number of pulses (P _L ) corresponding to the length is 136 or more (S15), the size data flag A3F of the A3 size is set to “1” (S1).
6) Specify A3 size paper.

According to such a series of pulse counting operations and document size determination processing, the upstream sensor 40a detects the leading edge of the document and the downstream 40b detects the trailing edge of the document, so that the upstream and downstream individual sensors detect the leading and trailing edges of the document. Since different points (leading edge and trailing edge) of the document are detected, variations and errors in the count value due to slipping or bending of the document can be suppressed as compared with the case where size detection is performed by a single sensor. It is possible to execute the determination of the original size.

Next, the pulse counting operation of the automatic document feeder according to the third aspect will be described with reference to the flowchart of FIG. Similar to the pulse counting operation of the second aspect, when the document conveyance is started, it is determined whether the size flag and the count flag are reset ("0") (S21, S22). Next, when the leading edge of the document separated and conveyed from the document bundle 80 is detected by the downstream sensor 40b and turned on (S23), the pulse counter 50b
_Is cleared (= 0) and the count flag is set to "1" (S24).
The counting of the pulse signal output from the pulse generator 50a is started in synchronization with the operation m (S25). When the original is sequentially conveyed toward the conveyance unit 20 and the rear end of the original is detected by the upstream sensor 40a and turned off (S26), the count flag is reset ("0") and the counting operation of the pulse counter 50b is stopped. (S27). The count value (P _CNT ) thus counted is subjected to a correction process of adding the number of pulses (P ₀ ) corresponding to the installation distance between the upstream sensor 40a and the downstream sensor 40b, which is known in advance, and corresponding number of pulses _{(P L = P CN T +} P 0) to calculate the (S28), and terminates the pulse counting is set to "1" to size flag (S29).

According to such a series of pulse counting operations and the above-described document size determination process (FIG. 4), the leading edge of the document is detected by the downstream sensor 40b and the trailing edge of the document is detected by the upstream sensor 40a. Since the counting operation is controlled, the time required for counting the number of pulses can be shortened as compared with the counting method described in claim 2, and the error relating to the counting and the variation or error of the count value due to slipping or bending of the document. Can be suppressed, and an appropriate document size can be determined.

Next, the pulse counting operation of the automatic document feeder according to claim 4 will be described with reference to the flowcharts of FIGS. The feature of the present invention _{resides in} that two types of count values (P _CNT ) obtained by the pulse counter 50b are obtained because the two sensors individually detect the leading and trailing edges of the document. Note that the same pulse counting operation is performed independently by the upstream sensor 40a and the downstream sensor 40b, and the description of the same process is omitted.

First, the pulse counting operation of the upstream sensor 40a will be described. Similar to the pulse counting operation according to the second and third aspects, when the document conveyance is started, the length in the conveyance direction is detected by the upstream sensor 40a. It is determined whether or not the upstream size flag and the count flag for determining whether or not are reset ("0") (S
31, S32). Next, when the leading edge of the document separated and conveyed from the document bundle 80 is detected by the upstream sensor 40a and turned on (S33), the count value (P _CNT1 ) of the pulse counter 50b is cleared (= 0) and the count flag is set to "".
1 "is set (S34), and counting of pulse signals output from the pulse generator 50a is started in synchronization with the operation of the paper feed motor 10m (S35). When the trailing end of the document is detected by the upstream sensor 40a and turned off (S36), the count flag is reset ("0") and the counting operation of the pulse counter 50b is stopped (S37).
A read completion flag for judging the completion of reading the count value (P _CNT1 ) is set to “1” and (S
38), the upstream size flag is set to “1”, and the pulse counting operation ends (S39).

In the pulse counting operation on the downstream sensor 40b side, after it is determined whether or not the downstream size flag and the count flag are reset ("0") (S41, S42), the leading edge of the document is moved downstream. Sensor 40b
When the ON state is detected (S43), the count value (P _CNT2 ) of the pulse counter 50b is cleared (= 0),
The count flag is set to "1" (S44), and counting of pulse signals is started (S45). Documents are sequentially transported by transport unit
When the document is conveyed in the zero direction and the downstream end of the document is detected by the downstream sensor 40b and turned OFF (S46), the count flag is reset ("0") and the counting operation is stopped (S46).
47) The downstream size flag is set to "1" (S48), and the two counted values ( _PCNT1 , PCNT1) are counted.
_CNT2 ) are compared, and if they are the same, any one of the count values is compared. If they are different, both are averaged to calculate the number of pulses equivalent to the length [P _L = (P _CNT1 + P _CNT2 ) / 2]. (S49), the size flag is set to "1", and the pulse counting operation is completed (S50).

According to such a series of pulse counting operations and document size determination processing, the upstream and downstream sensors individually detect the leading and trailing edges of the document and count the number of pulses. Type of count value (P _CNT1 ,
P _CNT2 ) can be obtained, and the original size can be determined based on the count value (P _L ) obtained by comparing and averaging these two values. The number of pulses (P _L ) corresponding to the length can be calculated more accurately than in the above case, and variations and errors in the count value due to slipping or bending of the document can be suppressed.

Although the copying machine has been described as an example of an image processing apparatus to which the automatic document feeder of the present invention can be applied, it is needless to say that the present invention is not limited to this. Also, the configuration has been described in which the upstream and downstream document detection sensors for controlling the pulse counting operation, which is a feature of the present invention, are arranged in the paper feeding section of the copying machine. It is sufficient that the sensor is arranged in a necessary path, for example, in a transport path up to the image processing step, and it is particularly desirable to use an existing sensor in the image processing apparatus.

[0039]

According to the first aspect of the present invention, the count start and end operations of the pulse counter are controlled by the two document detection sensors on the upstream side and the downstream side which are also installed in the conventional apparatus, and the two sensors The document size is determined based on the count value within the period during which the document is detected, so that a new configuration such as a document guide or a potentiometer is not required to directly detect the document size, and two sensors are used. And detects the original, and corrects the count value counted by the pulse counter to calculate the pulse value equivalent to the original length. The document size can be appropriately determined while suppressing the document size.

According to the second aspect of the present invention, the leading edge of the document is detected by the document detection sensor disposed on the upstream side of the document conveyance path, pulse counting is started, and the detection of the document disposed on the downstream side is started. From the count value obtained by detecting the trailing edge of the document by the sensor and stopping the pulse counting, the number of pulses corresponding to the length of the document in the document transport direction can be calculated to determine the document size. In addition, when a single sensor is used, it is possible to suppress variations and errors in the count value due to slippage and bending during document conveyance.

According to the third aspect of the present invention, the leading edge of the original is detected by the original detection sensor disposed downstream of the original conveyance path, and pulse counting is started, and the detection of the original disposed upstream is detected. Since the sensor detects the trailing end of the document and stops the pulse counting and counts the number of pulses, the period counted by the pulse counter can be shortened. Variations and errors in the count value due to deflection can be suppressed.

According to the fourth aspect of the present invention, since the upstream and downstream document detection sensors provided in the document conveyance path each independently count the number of pulses, these two count values are compared and compared. By performing the averaging process, the number of pulses corresponding to the transport length of the document is optimized, and the influence of the variation in the count value and the error due to slippage and deflection during document transport can be reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a basic configuration of an automatic document feeder according to the present invention according to claim 1;

FIG. 2 is a diagram showing a schematic configuration of an image processing apparatus to which the automatic document feeder of the present invention can be applied.

FIG. 3 is a flowchart showing a pulse counting operation of the automatic document feeder according to claim 2;

FIG. 4 is a flowchart illustrating a document size determination process of the automatic document feeder according to the present invention.

FIG. 5 is a flowchart showing a pulse counting operation of the automatic document feeder according to claim 3;

FIG. 6 is a flowchart showing a pulse counting operation of an upstream document detection sensor of the automatic document feeder according to claim 4;

FIG. 7 is a flowchart showing a pulse counting operation of a downstream document detection sensor of the automatic document feeder according to claim 4;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Copier (image processing apparatus) 1a Contact glass 10 Paper feeder 10a Document tray (document mounting table) 10b Recall roller 10c Paper feed roller 10d Reverse roller 10e Pull-out drive roller 10f Pull-out driven roller 10m Paper feed motor (drive means) 20 Conveying unit 20a Conveying belt 20b Conveying belt driving roller 20c Conveying belt driven roller 20d Pressure roller 20m Conveying motor (driving unit) 30 Discharge unit 30a, 30b Discharge tray 30m Discharge motor (driving unit) 40a, 40b Document detection sensor (First and second document detecting means) 50 Controller (control means) 50a Pulse generating section (pulse generating means) 50b Pulse counter (pulse counting means) 50c Document size determining section (document size determining means) 60 Operating section 70 Interface 80 Document Bundle 1 0 automatic document feeder

Claims (4)

[Claims] A first document detecting means provided at a predetermined position in the conveying path for detecting a document conveyed by the document conveying means; A second document detecting means provided in the transport path behind the first document detecting means in the transport direction behind the first document detecting means, and a driving means for driving the document transport means in synchronism with the operation of the driving means. Pulse generation means for outputting a predetermined pulse signal; pulse number counting means for counting pulse signals output from the pulse generation means based on detection signals from the first and second document detection means; A predetermined correction process is performed on the number of pulses counted by the number counting means to control the start and end operations of the document size determination means for determining the size of the document and the pulse number counting means. An automatic document feeder, characterized by a control means for controlling the operation processing according to the pulse number correction processing document size determination means. 2. The automatic document feeder according to claim 1, wherein said control means comprises: said pulse number counting means;
The counting is started when the leading edge of the document is detected by the document detecting means, and the counting is terminated when the trailing edge of the document is detected by the second document detecting means. An automatic document control unit that controls the document size determination unit to subtract the number of pulses corresponding to the separation distance between the first and second document detection units from the number of pulses counted by the pulse number counting unit. Transport device. 3. The automatic document feeder according to claim 1, wherein said control means comprises: said pulse number counting means;
The counting is started when the leading edge of the document is detected by the document detecting means, and the counting is stopped when the trailing edge of the document is detected by the first document detecting means. The document size determining means determines the first and second pulses according to the number of pulses counted by the pulse number counting means.
Wherein the number of pulses corresponding to the separation distance of the document detecting means is controlled to be added. 4. The automatic document feeder according to claim 1, wherein said control means comprises: said pulse number counting means;
The counting is started when the leading edge of the document is detected by the document detecting means, and the counting is terminated when the trailing edge of the document is detected to obtain a first pulse number. The counting is started when the leading edge of the document is detected by the second document detecting means, and the counting is terminated when the trailing edge of the document is detected to obtain a second pulse number. An automatic document feeder, wherein the document size determination means controls so as to average the first and second pulse numbers counted by the pulse number counting means.