JPH07291485A - Double feed sensing device and document conveying device equipped with the same - Google Patents

Abstract

PURPOSE:To prevent misjudgement in the case thicker paper is conveyed after thin sheets of paper are conveyed continuously by measuring the displacement of a follower roller and the incremental time during the period a document sheet passes between rollers, and passing the judgement whether the sheet is ordinarily thin or of thick type. CONSTITUTION:A conveying roller 22 and an idling roller 23 are installed as pinching the document conveying path R of an automatic document feeding device. Over the idling roller 23, an optical micro-displacement sensor 21 is installed to measure the displacement amount of the roller 23 and the time of displacement. When a document sheet intrudes between the conveying roller 22 and idling roller 23, the idling roller 23 is displaced, and the amount of displacement further increases in the event of double feed of sheets. In the case of ordinary double feed, a certain dislocation will exists between the first document sheet and the second so that the increase in the displacement amount takes place at two stages. If the incremental time (t0) of the change amount is large at a double feed-like phenomenon, judgement is passed that a double feed is happened, and if the incremental time (t0) remains small, judgement is passed that the document sheet is equipped with any affixed matter such as photo, revenue stamp, etc.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a double feed detecting device for detecting double feed of documents or the like in an image recording device such as a copying machine or a facsimile.

[0002]

2. Description of the Related Art An automatic document feeder (hereinafter referred to as an ADF) which is mounted on a copying machine, a facsimile or the like and automatically conveys a document to a reading position is well known. In these image recording apparatuses, when an ADF is used to automatically convey originals and two or more originals are overlapped and conveyed, a double feed occurs, which means that some originals are not read, and information ( (Documents) will be missing.
Therefore, if a double feed occurs in the ADF, the original purpose of the image recording apparatus, such as information management storage and document creation, cannot be achieved.

Therefore, in the conventional ADF, a separation roller, a friction plate, or the like is used to reliably convey the originals one by one. However, since the manuscript has various kinds such as its thickness and waist strength, it is very difficult to completely eliminate the double feed by the above method. Therefore, even if the double feeding cannot be completely eliminated, if the occurrence of the double feeding can be confirmed, it can be considered that information loss can be prevented by reading the double fed document again. In recent years, based on this idea, an ADF equipped with a double-feed detection device that detects double-feed of documents has been proposed.

As a conventional double-feed detection device, a device for detecting the amount of transmitted light of an original document or a mechanical displacement generated between the rollers when the original document passes a pair of conveying rollers is output voltage of the differential transformer. The one that is converted and detected has been proposed. However, these are not satisfactory in terms of detection accuracy and reliability.

Therefore, when an original passes through a pair of conveying rollers, an electric signal corresponding to the amount of displacement generated between the rollers is output, the output signal is sampled after a lapse of a predetermined time from the start of the conveying roller, and sampling is performed. There has been proposed a multi-feed detection device that discriminates multi-feed according to the output signal.

For example, in Japanese Patent Laid-Open No. 61-197348, the average value of the sampling data before the present and the current (latest) data are compared to determine the double feeding, so that the waveform of the output signal A double-feed detection device is shown which eliminates the effect of transient ripple that occurs at the initial stage of rising.

[0007]

However, in the double feed detecting apparatus described in the above publication, the double feed is detected by comparing the average value of the past data with the latest data. When the thick paper is conveyed after the paper is continuously conveyed, there is a problem that it is erroneously detected as a double feed.

Further, the conventional double-feed detecting device has a problem that a document with an attached material is erroneously detected as a double-feed.

The present invention solves the above-mentioned problems in the conventional double-feed detecting device, and provides a more reliable double-feed detecting device which prevents erroneous detection while determining the double-feed for each sheet. Is an issue.

Another object of the present invention is to prevent erroneous detection in the case of a manuscript having a pasting object.

[0011]

SUMMARY OF THE INVENTION According to the present invention, the above-described problems are solved by a conveying roller for conveying an original and a driven roller which is pressed against the conveying roller with a predetermined urging force and can be displaced according to the thickness of the original. A double-feed detection device, which is disposed in association with a document transport mechanism having a roller and determines double-feed of the document based on a displacement amount of the driven roller by a document nipped and transported by the both rollers, The problem can be solved by having control means for prohibiting the double-feeding determination when the increase time of the displacement amount of the driven roller detected during the passage of the document is shorter than a predetermined time.

The present invention also proposes that the predetermined time can be adjusted in order to solve the above problems.

In order to solve the above-mentioned problems, the present invention further comprises a pasted object position input means for inputting the position of the pasted object pasted on the original in the original conveying direction,
It is proposed to prohibit double feed determination at the position input by the input means.

Further, according to the present invention, in order to solve the above-mentioned problems, the document conveying mechanism is provided so as to be movable in a direction perpendicular to the document conveying direction, and is arranged in association with the document conveying mechanism. It is proposed that the feeding detection device is provided so as to be movable integrally with the document conveying mechanism.

Further, according to the present invention, in order to solve the above-mentioned problems, a conveying roller for conveying an original and a driven roller which is pressed against the conveying roller with a predetermined urging force and can be displaced according to the thickness of the original. A plurality of manuscript conveying mechanisms having rollers are arranged in a direction perpendicular to the manuscript conveying direction, and a displacement amount of the driven roller by a manuscript which is arranged in association with each manuscript conveying mechanism and is nipped and conveyed by the both rollers is A double-feed detection device that determines the double-feed of an original based on the double-feed detection when the increase amount of the displacement amount of the driven roller detected while the original is passing between the rollers is shorter than a predetermined time. It is proposed to provide a plurality of double feed detection devices having control means for controlling to prohibit.

Further, in order to solve the above-mentioned problems, the present invention provides a double feed when all of the plurality of double feed detection devices provided in association with the respective document conveying mechanisms are determined to be double feed. Suggest to send.

[0017]

The displacement amount of the driven roller increases when the double-fed original having the misaligned leading edge passes between the conveying roller and the displaceable driven roller (the driven roller is displaced by the first original,
The amount of displacement increases due to double-fed documents). In addition, the displacement of the driven roller also increases in the case of a document with a sticking object (the driven roller is displaced by the document itself, and the displacement amount further increases due to the sticking object on it). However, the pasted material rarely extends over the entire length of the original, and the time during which the amount of displacement of the driven roller increases due to the pasted material is shorter than the time when the amount of driven roller displacement increases due to the double-fed original. Can be assumed. Therefore, even when the displacement amount of the driven roller increases while the document passes between the transport roller and the driven roller (during time), the time period during which the displacement amount increases is shorter than a predetermined time period set in advance. In this case, by prohibiting the determination of double feeding, it is possible to prevent erroneous detection of the pasted object as double feeding.

Other functions will be apparent from the description of the embodiments below.

[0019]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 5 schematically shows a scanner (image reading device) equipped with an ADF to which an embodiment of the double feed detecting device of the present invention is attached.

The scanner 1 shown in this figure mainly comprises an image reading section 2 and an ADF 10. The image reading unit 2 includes a first traveling body 3 for movably supporting a fluorescent lamp and a first mirror for illuminating an original, a second traveling body 4 for movably supporting second and third mirrors 4, and a condenser lens. 5, CC
D6 and the like are arranged below the contact glass 7. A document retainer 8 is installed on the upper surface of the contact glass 7 so as to be openable. Then, the ADF 10 is mounted on the upper end of the image reading unit 2 on one end side of the apparatus. Inside the ADF 10, a separating roller pair 11 and conveying roller pairs 12 and 13 are arranged across the document conveying path R. Further, the document table 9 is installed at the document insertion port. Note that the document holder 8
Also serves as the document discharge table of the ADF 10. The scanner 1 has a book mode and an ADF mode.
First, the book mode will be described.

In the book mode, the document surface of the document faces downward, and the contact glass 7 under the document holder 8 is pressed.
Placed on top. When instructed to start scanning the original,
The original is scanned while the first and second traveling bodies 3 and 4 move, and the reflected light from the original illuminated by the fluorescent lamp is reflected by each mirror and is incident on the CCD 6 through the condenser lens 5. It The CCD 6 photoelectrically converts the reflected light from the original, and the analog electric signal is subjected to signal amplification and digital conversion in an image processing unit (not shown), and then various corrections are made to the host computer (not shown) to which the scanner 1 is connected. Output).

In the ADF mode, a plurality of originals are set on the original table 9 with their image surfaces facing up.
Among the plurality of originals, the lowest original separated into one by the separation roller pair 11 is conveyed in order, and is conveyed at a constant speed through the original conveyance path R by the conveyance rollers pair 12 and 13 to move the paper to the discharge table. The document is discharged onto the double-sided document holder 8. During this period, the original conveyed by the fluorescent lamp of the first traveling body stopped at the predetermined reading position is irradiated with light,
The reflected light from the document enters the CCD 6 through the first mirror, the respective mirrors of the second traveling body which are also stopped at a predetermined position, and the condenser lens 5. The subsequent signal processing is the same as in the book mode.

Next, a double feed detection device mounted on the ADF 10 of the scanner 1 will be described. The double feed detection device is A
Although it is arranged in the document conveying path R of the DF 10, in this embodiment, it is arranged immediately downstream of the separation roller pair 11. Details of the double feed detection device will be described with reference to FIGS. 1 and 2. In FIG. 1, the separation roller pair 11 is replaced with the paper feed roller 14 and the separation plate 15 for description.

In the double feed detection device 20 shown in FIG.
A conveyance roller 22 and an idle roller 23 are arranged across the document conveyance path R of F10. A leaf spring 25 is fixed to a support member 24 that supports the idle roller 23. The leaf spring 25 is fixed to the frame of the ADF 10 and presses the idle roller 23 against the transport roller 22. The idle roller 23 can be displaced in a direction (direction of arrow S) perpendicular to the document conveying direction according to the thickness of the document entering between the rollers. A white sticker 26 is attached to the upper surface of the tip of the leaf spring 25. further,
Above the idle roller 23, the optical micro displacement sensor 2
1 is arranged. The optical micro-displacement sensor 21 holds LEDs (light emitting diodes), PSDs (silicon photodiodes) and PS (not shown) and PS.
And a light shield covering D. The light shield has a slit on the surface facing the white sticker 26,
The light emitted from D is reflected by the white sticker 26, and a part of the reflected light enters the PSD through the slit. PSD is
It is a photoelectric element that generates a photoelectromotive force when receiving light, and outputs a current according to the amount of incident light. The output current is sent to the CPU (not shown) via the lead wire 27.

By the way, the original to be conveyed is conveyed by the conveying roller 2.
When passing between 2 and the idle roller 23, the idle roller 23 is displaced upward by the same amount as the thickness of the document. Accordingly, the white sticker 26 is also displaced in the same direction by the same amount as the displacement amount of the idle roller 23. When the white sticker 26 is displaced, the amount of light reflected by the white sticker 26, passing through the slit of the light shield (not shown) and entering the PSD changes, and P
The SD output changes. The output waveform of the optical micro-displacement sensor 21, that is, its PSD, at this time is shown in FIG.
It becomes like (a). In addition, in FIG. 2, the output of the PSD is represented by the displacement amount. As can be seen from this figure, the PSD output changes when the document enters between the transport roller 22 and the idle roller 23, and the PSD output returns to the original when the document trailing edge passes between both rollers. (There is no output change during that time).

Normally, in the original stack P shown in FIG. 1, the lowest original P ₁ is fed by the paper feed roller and the separating plate 15 (A in FIG. 5).
In the DF, the sheets are separated and fed into one sheet (by the pair of separating rollers 11), but when double feeding occurs, a plurality of sheets of documents are fed. Assuming that double feeding two documents as shown in FIG. 1 is fed occurs, second document P ₂ from the lowermost document P ₁ shifted slightly rearward are fed . The output waveform of the PSD at this time is as shown in FIG.
That is, the output of the PSD changes when the first original enters between the transport roller 22 and the idle roller 23, and then the output changes further when the second original enters between the rollers. ing. Conventionally, the output change of PSD is 2
It was possible to determine that the document was double-fed at the time when it was returned. PSD as shown
Output change occurs twice. Therefore, when it is determined that there is a double feed when there is a change in the output of the PSD twice, a double feed may be erroneously detected even if there is a pasted object on the document. In view of this, in the present invention, attention is paid to the time period during which the amount of displacement increases while the document passes between the transport roller 22 and the idle roller 23, that is, the time period during which the second PSD output changes in the embodiment. . As long as the document is passing between the transport roller 22 and the idle roller 23, if the document is not double-fed, the displacement amount does not increase as shown in FIG. Does not change). On the other hand, in the case of a double-fed document, the displacement amount increases (the PSD output changes) as shown in (b). In addition, the displacement amount increases as shown in (c) when the original has an attached object. It should be noted that the time period during which the document passes between the transport roller 22 and the idle roller 23 can be determined when the PSD output value changes from normal and returns to the original normal output value.

By the way, in general double feeding, the first (normally fed) original and the second (double feeding) original are often slightly displaced in the carrying direction. However, the deviation is unlikely to be large as shown in FIG. 3A, and the overlapping portion is often large as shown in FIG. 3B. This is because in the case of (a), the frictional force between the upper and lower originals is small and double feeding is less likely to occur. Therefore, it can be assumed that a general double feed has a large overlapping portion as shown in (b). The increase time of the displacement amount at this time is longer than the increase time of the displacement amount in the case where the pasted material is present on the normally fed document. This is because the pasted items are often relatively small, as represented by photographs and stamps. Even if a fairly large one is pasted, it is rare that the pasted material is attached over the entire length of the manuscript. Figure 2 compares the increase time of the displacement amount when double feeding and when there is an attached object.
It becomes like (b) and (c). As shown in FIG. 2B, the increase time of the displacement amount at the time of double feeding is t _0, and as shown in FIG. 2C, the increase time of the displacement amount is t.
_{When set to 1} , it can be generally assumed that t ₀ > t ₁ . Therefore,
In the present invention, when the amount of increase in the displacement amount is equal to or less than the predetermined value, it is controlled so as not to be determined as double feeding.

That is, in the embodiment, when the PSD output changes twice and the time during which the second output change exceeds the predetermined time, it is determined that the double feeding is performed. Conversely, even if the PSD output changes twice, if the second output changing time is shorter than the predetermined time, it is not determined as a double feed. Therefore, even if the original has an attached material, it is possible to prevent erroneous detection of determining that the original is a double feed. It should be noted that the ADF CPU performs all of the output changes of the PSD, the monitoring of the changing time and the determination of the double feeding based on the changes.

By the way, when the predetermined time period for prohibiting the double feed determination is set to be large (long), the double feed is not determined even if the patch is large, so that the erroneous detection is reduced.
This time, there is a risk that false positives that true double feeds are not detected will increase. Therefore, in this embodiment,
The user can set a predetermined time for prohibiting the determination of double feed. As a result, more accurate double feed detection can be performed for various originals. The predetermined time may be set from the ADF operation panel or a host computer connected to the ADF.

Further, in the case of a manuscript in which the pasted matter is pasted at a predetermined position (for example, various application sheets or application sheets), the user can determine the position of the pasted article (position in the conveying direction). By giving an instruction, false detection can be reduced. That is, in this embodiment, the position (position in the transport direction) of the pasted object is set from the operation panel of the ADF or the host computer connected to the ADF, and the amount of displacement increases at the set position (P
If there is a change in the SD output), control is performed so that it is not judged as a double feed.

Further, in the present embodiment, the double feed detection device 20 shown in FIG. 1 is provided so as to be movable in the direction (original width direction) perpendicular to the document feeding direction, as shown in FIG. Then, in the case where the original P ₀ is an original in which the pasted object is pasted at a predetermined position, the movable double-feed detection device is arranged at a position avoiding the pasted object, and at that position. By performing the detection operation, erroneous detection can be prevented and more accurate double feed detection can be performed.

Next, another embodiment of the present invention will be described. The basic configuration of the ADF in this embodiment is similar to that of the ADF 10 of the scanner 1 shown in FIG. However, in this embodiment, as shown in FIG. 6, three double feed detecting means 20a, 20b, 20c arranged in a direction perpendicular to the document conveying direction are provided. The structure of each of the double feed detecting means 20a, 20b, 20c is the same as that of the double feed detecting device of the above-described embodiment described with reference to FIGS.

FIG. 7 shows output waveforms of the multi-feed detecting means 20a, 20b, 20c when the original document P ₀ having the attached material as shown in FIG. 6 is conveyed. As can be seen from FIG. 7, the output waveform of the double-feed detection means 20b in the portion where the sticking object is present has a form in which there are two-stage output changes (FIG. 7-b). On the other hand, the output waveforms of the multi-feed detecting means 20a and 20c in the part without the sticking material each have only one-stage output change (FIG. 7).
a, c).

On the other hand, when the document is double-fed, as shown in FIG. 8, the output waveforms of the three double-feed detection means 20a, 20b, 20c are the same, and there are two stages of output changes. It has a shape.

Therefore, in the present embodiment, if there is any one of the three double feed detecting means 20a, 20b, 20c that does not determine the double feed, it is determined that the double feed is not performed. In other words, the three double feed detecting means 20a, b, c
When it is determined that all documents are double-fed, it is determined that the document has been double-fed. The double feed determination by each of the double feed detection means is similar to the above-described embodiment, in that the double feed is determined when the increase time of the displacement amount exceeds a predetermined value. By combining the double feed determination in each double feed detection unit and the double feed determination by the three double feed detection units 20, it is possible to perform the double feed detection with higher accuracy. For example, if the pasted material on the original is large and one or two double feed detecting means determines that there is a double feed, it will not be determined as a double feed if the remaining one does not determine a double feed, thus reducing false detections. Can be made.

[0037]

As described above, according to the double feed detection apparatus of the present invention, when the displacement amount of the driven roller increases while the document passes between the conveying roller and the driven roller (during time). However, if the time during which the amount of displacement is increasing is shorter than the predetermined time set in advance, the determination of double feeding is prohibited. It is possible to detect multiple double feeds.

According to the structure of the second aspect, the predetermined time for prohibiting the double-feeding determination can be adjusted, so that the double-feeding detection can be surely performed corresponding to various originals.

According to the third aspect of the invention, since the position of the pasted object on the original is input and the determination of the double feed at that position is prohibited, it is possible to more reliably prevent erroneous detection.

According to the structure of claim 4, since the double feed detecting device can move in the direction perpendicular to the document conveying direction,
More accurate double feed detection can be performed while avoiding the position of the attached object.

According to the fifth aspect of the invention, since a plurality of double feed detecting devices are arranged in the direction perpendicular to the document conveying direction, more accurate double feed detection can be performed.

According to the structure of claim 6, when the plurality of arranged double feed detecting devices judge all the double feeds, it is judged as the double feed. Therefore, it is possible to more surely prevent the false detection of the pasted object as the double feed. You can

[Brief description of drawings]

FIG. 1 is a side view showing a configuration of an embodiment of a double feed detection device of the present invention.

FIG. 2 is a waveform diagram showing a waveform of a detection output by the double-feed detection device. (A) shows an output waveform when one original is fed, and (b) shows a case where the originals are double-fed. Output waveform of
(C) shows output waveforms when the original has an attached material.

FIG. 3 is a diagram for explaining a conveyance state of multi-fed originals. FIG. 3A is a view showing a multi-fed original with few overlapping portions.
(B) shows double-fed originals having large overlapping portions.

FIG. 4 is a plan view showing that the multi-feed detection device shown in FIG. 1 is provided so as to be movable in a direction perpendicular to the document conveyance direction.

5 is a cross-sectional configuration diagram showing an image reading apparatus provided with a document feeding mechanism to which the multi-feed detection device shown in FIG. 1 is mounted.

FIG. 6 is a plan view illustrating a document feeder including a plurality of double feed detection units.

FIG. 7 is a waveform diagram showing an output waveform of each multi-feed detection unit in the case of a document having a pasting object in the document conveying apparatus.

FIG. 8 is a waveform diagram showing an output waveform of each double-feed detection unit in the case of a double-feed original in the original feeding apparatus.

[Explanation of symbols]

1 Scanner 10 ADF 11 Separation Roller Pair 12, 13 Conveyance Roller Pair 20 Double Feed Detection Device 20a, b, c Double Feed Detection Means 21 Optical Micro Displacement Sensor 22 Transport Roller 23 Idle Roll 25 Leaf Spring 26 White Sticker P ₀ , P ₁ , P ₂ document t ₀ , t ₁ displacement amount increase time

Claims (6)

[Claims] 1. A document transport mechanism having a transport roller for transporting a document and a driven roller which is pressed against the transport roller with a predetermined urging force and can be displaced according to the thickness of the document. In the double feed detection device for determining the double feed of the document based on the displacement amount of the driven roller by the document nipped and conveyed by the both rollers, the driven roller detected while the document passes between the both rollers. The double feed detection apparatus having a control means for controlling the double feed determination to be prohibited when the increase time of the displacement amount is shorter than a predetermined time. 2. The double-feed detection device according to claim 1, wherein the predetermined time is adjustable. 3. A sticking material position input means for inputting a position of a sticking material stuck to a manuscript in a manuscript conveying direction, wherein a double feed judgment is prohibited at a position inputted by the input means. The multi-feed detection device according to claim 1, which is characterized in that. 4. The document feeding mechanism is provided so as to be movable in a direction perpendicular to the document feeding direction, and a double feed detection device provided in association with the document feeding mechanism is integrated with the document feeding mechanism. The double feed detection device according to claim 1, wherein the double feed detection device is movably arranged. 5. A document transport mechanism having a transport roller for transporting a document and a driven roller that is pressed against the transport roller with a predetermined biasing force and is displaceable according to the document thickness, at a right angle to the document transport direction. In a plurality of different directions, arranged in association with each of the document transport mechanisms, and configured to determine the double feed of documents based on the displacement amount of the driven rollers by the documents sandwiched and transported by the rollers. A plurality of double feeds having a control means for prohibiting the double feed determination when the increase time of the displacement amount of the driven roller detected while the document passes between the rollers is shorter than a predetermined time. A document transporting device comprising a detection device. 6. The multi-feed is determined when all of the plurality of multi-feed detection devices arranged in association with each of the document transport mechanisms determine the multi-feed.
The document feeder according to item 1.