JPH10120247A - Automatic document feed device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce operator's burden in work and prevent the interruption of the copying work by stopping the conveyance of documents which are fed in an overlapped condition at a position of a document separation means provided at a position in front of a platen and separating the documents which are fed in the overlapped condition by the document separation means for conveyance when the occurrence of the conveyance of overlapped documents is detected by an overlapped feed detection sensor. SOLUTION: When many documents on a documents tray 11 are copied one by one according to the predetermined order of pages, a lowermost document paper is supplied. If two documents or more are supplied and fed at the same time, the overlapped feed of the document paper is detected by an infrared ray emitting part 14a and an infrared ray receive part 14b. Then, a control part stops the operation of an automatic document feed device once at a position where a tip of the documents which are fed in an overlapped condition reaches an overlapped feed document stop 15 and a paper separation roller 16, then the paper separation roller 16 moves to an overlapped feed document stop 15 side to nip the documents which are fed in an overlapped condition, and a pick-up roller 13 operates in such a manner that it opens the documents. The paper separation roller 16 is rotated in the direction of supply and feed in this condition, and only the document on a lower side which is in contact with the paper separation roller 16 is supplied and fed to a platen 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic copying machine,
The present invention relates to an automatic document feeder (ADF) used in an image forming apparatus such as a printer or a facsimile machine, and more particularly to an image forming apparatus having a double feed detection sensor for detecting whether or not a document conveyed from a document tray is in a double feed state. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic document feeder capable of feeding originals to a reading position in an original feeding order without interrupting a document reading operation when a double feed occurs and performing complicated manual double feed processing.

[0002]

2. Description of the Related Art In an image forming apparatus, an automatic document feeder is arranged on a document table (contact glass) on an upper surface of an apparatus body to feed documents one by one to a reading position on the document table in a predetermined order. In this case, the sequentially read images are formed on a transfer material such as transfer paper and then discharged. By the way, in the copying operation using the automatic document feeder, when a double feed of documents occurs when the document is transported from the automatic document feeder to the platen, conventionally, the operation of the entire apparatus is stopped and the display is simultaneously displayed. Doing so informs the operator that a multifeed has occurred, or separates the multifeed documents and outputs them outside the machine, and the operator resends them with the automatic document feeder,
Either method was adopted. However, in the above-described conventional multi-feed processing method, a series of document reading is interrupted each time a multi-feed occurs, so that the troublesome work of re-feeding the multi-feed document again manually or the sorting of the discharged document is required. Since work is required, improvement of this point has been demanded.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above, and in an image forming apparatus provided with an automatic document feeder, the structure is complicated or the document reading operation is interrupted when a double feed occurs. An automatic document feeder that reduces the work load on the operator and prevents interruption of copying by enabling feeding to the reading position in the original feeding order without performing complicated manual processing. It is intended to provide.

[0004]

In order to achieve the above object, the present invention conveys a document placed on a document tray onto a platen, copies the required number of copies, and then copies the document. A document feeder for discharging the document to the output tray, a double feed detection sensor for detecting when the document sent from the document tray is being multi-fed, and a document feeder based on a detection signal from the double feed detection sensor. A control unit for controlling the operation of the means, the control unit, when the occurrence of double feed is detected by the double feed detection sensor, to set those documents in front of the platen The conveyance is stopped at the position of the original separating means, and the multi-fed originals are separated by the original separating means and conveyed one by one onto the original platen in the original feeding order.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to embodiments shown in the drawings. FIG. 1 is a longitudinal sectional view showing a schematic configuration of an automatic document feeder according to an embodiment of the present invention, FIG. 2 is a flowchart showing an operation example, and FIG. 3 is a block diagram of an example of a double feed detection circuit. . In FIG. 1, reference numeral 1 denotes an image forming apparatus main body, on which an original table (contact glass) 2 is provided, and on the original table 2, an automatic document feeder 3 is arranged. This automatic document feeder 3
Document tray 11 for setting a bundle of documents to be fed
And a paper feed roller 12 that rotates in contact with the lowermost document in the bundle of documents on the document tray 11 and feeds this out in the feed direction to the left of the drawing. , An infrared ray generating section (infrared light emitting element having high transmittance) 14a and an infrared ray receiving section (in a wavelength region near the infrared ray) which are arranged vertically above and below a document sent downstream of the pickup roller 13 Double feed detection sensor 1 comprising high sensitivity light receiving element having peak sensitivity) 14b
4, a double feed document stop member 15 and a sheet separation roller 16 which are disposed at the downstream side of the double feed detection sensor 14 at the upper and lower positions across the document conveyance path, and a pair of transport rollers 17 located further downstream, It has a transport belt 18, a reverse roller 19, a paper discharge roller 20, a paper discharge tray 21, and the like. The double feed document stopping member 15 is made of a member having a constant high coefficient of friction, and functions to stop the advance of the upper document by contacting the upper document with the flat lower surface. . Each transport unit from the pickup roller 13 to the paper discharge roller 20 constitutes a document feed unit. Also,
The double feed document stopping member 15 and the sheet separating roller 16 constitute a document separating unit.

In the above configuration, a large number of documents set on the document tray 11 are arranged in a predetermined page order (from the first page,
When the sheet is fed one by one onto the document table 2 and copied (from the last page), the lowermost document sheet is fed by the sheet feed roller 12 and the pickup roller 13 (FIG. 2, S1). When a double feed in which two or more originals are fed at the same time occurs, the infrared light emitting unit 14a and the infrared light receiving unit 14b detect double feed of the original paper (S2). A control unit (CPU, RO, not shown) that has received a signal of detecting a double feed from the double feed detection sensor 14.
M, RAM, I / O, etc.), temporarily stop the operation of the automatic document feeder, stop the double feed document stop 15 (the material is the same as the paper feed roller), and separate the paper The operation of the automatic document feeder is temporarily stopped at the position where the rollers 16 are reached (S5). Subsequently, the paper separating roller 16 moves to the double feed document stopper 15, and the pick-up roller 13 operates to open the document while simultaneously sandwiching a plurality of multi-feed documents between the two 15 and 16 (S6). .

In this state, the control section starts rotating the paper separating roller 16 in the feeding direction (S7). Double feed document stopper 15
Is made of a block-shaped or plate-shaped high-friction material as shown in the drawing, so that the upper original is brought into contact with the flat lower surface thereof.
Even if the paper separating roller 16 rotates in the feeding direction, the upper document does not advance from that position, and only the lower document (the original to be fed first) in contact with the paper separating roller 16 is transferred to the platen. It is fed toward. As a result, only the lower document escapes from the stop position and is read at the reading position. When the preceding document is retracted from the position of the double feed detection sensor 14 and it is detected that the original is not in the double feed state (S
8), the paper separating roller 16 is separated from the multi-feed document stopper 15, and the pickup roller 13 returns to the state shown in FIG.
The mode shifts to the normal copy mode (S3). At this time, the paper feeding units 13 and 16 temporarily feed the original document until the interval in the feeding direction between the first original fed earlier and the remaining upper original returns to the interval for normal copying. After the operation is stopped, rotation for resuming feeding is started, and the upper document is fed onto the document table. With this configuration, the multi-fed document is fed to the reading position in the original order without any special manual operation, and smooth reading is performed without interruption.
This eliminates the need for manual resending of multi-fed originals when multi-feeding occurs, and also prevents complications in sorting out discharged originals.

The double feed detecting sensor 14 is connected to a double feed detecting circuit including a logarithmic amplifier 30 and an A / D converter 31 as shown in FIG. When the document blocks the infrared light from the infrared light emitting unit 14a, the output from the infrared light receiving unit 14b is inversely proportional to the number of documents passing in the multi-feed state in an exponential manner, so that the output signal is logarithmically amplified. A linear output signal that is input to the circuit 30 and corrected and output by the logarithmic amplifier circuit 30 is input to the A / D conversion circuit 31, and the digitized signal is guided to the control unit 32 to determine the presence or absence of double feed, the number of sheets, and the like. Is determined. In the above-described embodiment, the case where the present invention is applied to the lower paper feeding type in which paper is fed from the bottom of the original on the document tray is shown, but this is an example, and the present invention is applied to the upper paper feeding type. It can also be applied to a paper feeding device. In this case,
The vertical positional relationship between the double feed document stopper 15 and the paper separating roller 16 may be reversed.

[0009]

As described above, according to the present invention, in an image forming apparatus provided with an automatic document feeder, the configuration becomes complicated, and the document reading operation is interrupted when a double feed occurs, thereby complicating manual processing. By performing feeding to the reading position in the original feeding order without performing the above operation, it is possible to reduce the work load on the operator and prevent interruption of the copying operation. As a result, the operator is free from complicated work such as resending multi-fed originals and organizing discharged originals and copy sheets.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a sheet feeding device according to an example of the present invention.

FIG. 2 is a flowchart illustrating an operation example of the sheet feeding device of FIG. 1;

FIG. 3 is a configuration diagram of an example of a double feed detection circuit.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Image forming apparatus main body, 2 Original platen (contact glass), 3 Automatic document feeder, 11 Original tray, 12
Paper feed roller, 13 Pickup roller, 14 Double feed detection sensor, 14a Infrared ray generating section, 14b Infrared light receiving section, 15 Double feed document stopping member, 16 Paper separating roller, 1
7 Conveyor roller pair 18 Conveyor belt, 19 Reverse roller,
20 discharge rollers, 21 discharge trays, 32 control unit.

Claims (1)

[Claims] A document feeder for feeding a document placed on a document tray onto a document table and reading a document image, and then discharging the document to a document discharge tray; A double feed detection sensor that detects when the incoming document is double fed, and a control unit that controls the operation of the document feeding unit based on a detection signal from the double feed detection sensor;
In the automatic document feeder provided with, when the double feed detection sensor detects the occurrence of double feed, the control unit stops transporting those documents at a position of a document separating unit provided at a position before the document table. An automatic document feeder, wherein the multi-feed document is separated by the document separating means and conveyed one by one onto a platen in an original feeding order.