JPH09142699A - Document double feed detecting device and method for image reading device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a document double feed detecting device of high reliability appropriately detecting double feed, even when documents are carried while piling up in a deviated state. SOLUTION: A paper length detecting device 5 measuring the length in the carrying direction of a carried document and a paper thickness detecting device 7 measuring the thickness of the document measured in the length are arranged on a paper sheet carrying passage 13 between the paper feed tray 1 of an image reading device and an image reading part 8. The paper thickness detecting device 7 detects the thickness in the vicinity of the center of the document computed from the length of the document measured by the paper length detecting device 5. Even when the documents are deviatedly double-fed, the vicinity of the whole length center is the part piling up the documents, and hence double feed is detected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a document double feed detection apparatus and a detection method for detecting a double feed of automatically conveyed sheets in an image reading apparatus provided in an electronic copying machine, a facsimile, an ADF or the like.

[0002]

2. Description of the Related Art In an image reading apparatus having a paper feeding section for automatically feeding a plurality of sheets of paper, it is necessary to separate the original sheets into individual sheets and feed them to the reading section. Even if the performance of the separation mechanism is improved, it is difficult to solve 100% of the problem of double-feeding in which a plurality of originals are fed at one time. If double feed occurs in the image reading apparatus, a page with a plurality of documents will be lost. In order for the reading unit to read the missing page again, it is necessary to search for the missing page. However, the larger the number of document sets, the more the work charge becomes enormous. For example, inputting a huge amount of originals of the same paper type such as slips, inputting originals of different paper types, and the like, it is common to input originals of the same size for various paper types. In such a case, the work of finding the missing page is very difficult. For this reason, some image reading apparatuses are equipped with a multi-feed detection device so that when a multi-feed is performed, it can be detected and immediately dealt with.

Conventionally, as this type of document double-feeding detecting device, those described in Japanese Patent Laid-Open Nos. 5-43091 and 60-144256 are known. That is, JP-A-5-4
In No. 3091, a paper thickness detecting device for detecting the paper thickness of the original and a paper size detecting device for detecting the size of the original are arranged in the original conveying path, and the paper is obtained from these detecting devices. The information is compared with the paper thickness data, which is a standard for each paper size of the original, to determine the double feed. Further, in Japanese Patent Laid-Open No. 60-144256, as a concrete configuration of a paper thickness detecting device, a variable resistor for varying a resistance value according to a moving amount of a roller pivotally supported in contact with a document to be conveyed is supported. When a double feed is provided with a container, the amount of movement of the roller becomes larger than usual and different resistance values are obtained, so that the double feed is detected.

[0004]

However, in the above-mentioned conventional double-feed detecting device, when the sheets are conveyed while being completely overlapped with each other, the double-feed is properly detected.
If the sheets are misaligned and stacked and conveyed,
There is a problem in the reliability of double-feed detection, because it may be mistakenly determined that the sheets are conveyed correctly by detecting a portion where the sheets do not overlap each other.

The present invention has been made in view of the above-mentioned problems of the prior art, and is a highly reliable document double feed detection device and detection which can detect double feed even when sheets are overlapped and conveyed in a shifted state. It is intended to provide a way.

Further, in the conventional double-feed detection device, an incorrect paper thickness is detected even when the paper is folded or wrinkled.
There was a problem that double feed was not properly judged.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a highly reliable document double feed detection apparatus and detection method which can properly detect double feed even when there are folds or wrinkles in the paper.

[0008]

According to a first aspect of the present invention, there is provided a document double feed detecting device for an image reading apparatus according to the first aspect of the present invention, which is on a sheet conveying path between a sheet feeding tray and an image reading section of the image reading apparatus. Is provided with a paper length detecting device for measuring the length of the conveyed document in the conveying direction and a paper thickness detecting device for measuring the thickness of the document whose length has been measured. A storage unit for pre-storing the thickness to be stored, and a determination unit for determining double feed by comparing the document thickness stored in the storage unit with the measurement value of the document thickness measured by the paper thickness detection device. The paper thickness detection device is characterized in that the thickness near the central portion of the document calculated from the length of the document measured by the paper length detection device is detected and used as a determination target measurement value.

According to the second aspect of the present invention, the paper thickness detection device measures the thickness at three locations near the central portion of the document calculated from the length of the document measured by the paper length detection device. The determination means detects the median value of the measured values and sets it as the determination target measurement value.

According to the third aspect of the present invention, the paper thickness detecting device determines the thickness at least at four places near the central portion of the document calculated from the length of the document measured by the paper length detecting device. It is characterized in that the determination means measures the average value of the data excluding the data of the maximum value and the minimum value among the measured values.

According to a fourth aspect of the present invention, there is provided a paper length detection device for measuring a length of a document to be conveyed in a conveyance direction on a paper conveyance path between a paper feed tray of the image reading device and the image reading section. , And a paper thickness detection device that measures the thickness of the document whose length has been measured at a plurality of points, and compares the measured values of the document thickness measured by the paper thickness detection device to perform double feeding. The paper thickness detection device measures the thicknesses at a plurality of points between the front end of the document and the rear end of the document measured by the paper length detection device. The present invention is characterized in that the data indicating the minimum value of the measured values at the points and the data in the central portion of the document are compared to judge the double feeding during the document transportation.

According to the fifth aspect of the present invention, the paper thickness detection device calculates at least the thickness of the front end portion, the central portion and the rear end portion of the document calculated from the length of the document measured by the paper length detection device. And the determination means compares the minimum value data of the measured values at the plurality of points with the data of the central portion.

According to a sixth aspect of the present invention, the paper thickness detecting device includes a front end portion, a central portion and a rear end portion of the document which are calculated from the length of the document measured by the paper length detecting device. The thickness is measured at least at three places, and the median value of the data measured at each part is used as the measurement value of each part, and the determining means determines the minimum value of the median values of these plural places and the center part of the document. Characterized by comparing data

According to a seventh aspect of the present invention, the paper thickness detecting device includes a front end portion, a central portion, and a rear end portion of the document, which are calculated from the length of the document measured by the paper length detecting device. The thickness is measured at least at four points, and the determination means
The maximum and minimum values of the data detected in each of these parts are deleted, the remaining data is averaged in each part, and the average and minimum values of the data at the leading edge, center, and trailing edge of the original are averaged. Characterized by comparing with the data in the center of the document

According to the eighth aspect of the document double feeding detection method of the image reading apparatus according to the present invention, the reference thickness of the fed document is stored in advance, and the sheet feeding tray of the image reading apparatus and the image are stored. The length of the document to be transported in the transport direction is measured on the sheet transport path between the reading unit and the center position of the document in the transport direction is calculated from the measured length, and the center of the document including the center position is measured. The thickness of the above document is measured at several places before and after the copy and its transport direction, and the median value of the measured data is used as the measurement value, and the thickness of the stored paper is compared with the thickness of the measured paper. When the measured thickness of the paper is thicker than the stored thickness of the paper, it is determined to be a double feed.

According to a ninth aspect of the present invention, at least the front end of the document in the transport direction of the document to be transported is provided on the paper transport path between the paper feed tray of the image scanning device and the image scanning unit.
When the thickness of the central part and the rear end part is measured at least at each one place and the data of the minimum value among the measured values at the above-mentioned plural places is compared with the data of the central part, and the comparison result does not satisfy the predetermined condition The feature is that it is judged to be a double feed.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic side view showing the overall configuration of a document double feed detection device according to the present invention, and FIG. 2 is a side sectional view showing a paper thickness measuring sensor which is an example of a paper thickness detection device. In these figures, 1 is a paper feed tray on which a large number of originals are stocked, 2 is a pickup roller for feeding the originals on the paper feed tray 1 onto a paper conveyance path 13, and 3 is a pickup roller 2.
Paper feed rollers 4 for receiving the originals from the rollers rotate in a direction opposite to the direction of the paper feed roller 3 when the multi-feed is performed, and separation rollers 4 and 5 for separating the superposed originals are lengths of the conveyed originals. A paper length detecting device for measuring the document thickness, 7 a paper thickness detecting device for measuring the thickness of the document, 6 a conveying roller for conveying the document to the paper thickness detecting device 7, 8 an image reading unit for reading an image on the document, 9 Is a paper discharge roller for discharging the document from the conveyance path 13.

A paper length detecting device 5 and a paper thickness detecting device 7 for detecting the length of a document are arranged on a paper conveying path 13 connecting the paper feeding tray 1 and the image reading portion 8 and are obtained by these detecting devices. Information on the length and thickness of the document to be printed is input to a calculation / control unit (not shown) to detect double feed. The paper length detecting device 5 detects the front end and the rear end of the conveyed document and measures the total length of the document in consideration of the document feed speed.

The measured length data of the original is sent to the calculation / control section, and the distance from the front end of the original to the central position is obtained.
In this case, as shown in FIG. 3C, when the originals are completely overlapped and fed, the original length becomes "a", and the distance "a / 2" to the center position is obtained. However, as shown in FIG. 3 (A) or (B), when the overlapped documents are misaligned and overlapped, the total length “a + b” of the originals is measured and the distance to the center position is measured. "(A
+ B) / 2 "will be calculated.

FIG. 2 shows a paper thickness measuring sensor 10 used as an example of the paper thickness detecting device 7. Reference numeral 11 denotes a light emitting element which emits light toward the paper surface of a document to be conveyed.
Is a light receiving element for receiving the light from the light emitting element 11 reflected on the original. Here, the optical path of the reflected light when there is no document on the paper transport path 13 is S1, and the optical path when one original 14 is transported by entering the upper portion of the light receiving element 11 is S2,
Light is incident on the center of the light receiving element 11, and two originals 14 and 15
When the light beam is transported, the optical path is S3, and the light enters the lower part of the light receiving element 11. When the original is not present, the proper conveyance and double feeding of the original are detected by the distances t1 and t2 from the incident position on the light receiving element 11. That is, the incident position "t1" of the light receiving element 11 in a proper conveyance state (the originals do not overlap) with respect to the conveyed original is stored in a storage unit (not shown), and the original thickness "t1 + t2" is measured when the original thickness is measured. If it is measured and a deviation t2 occurs, it is determined that the sheet is a double feed.

The paper thickness measuring sensor 10 is capable of continuously measuring the thickness of the original document being conveyed,
When measuring at three points close to each other, ignore the maximum and minimum values and use the median as the measured value.
Further, when the measurement is performed at four points, it is possible to ignore the maximum value and the minimum value among them and adopt the average value of the values at the two central points as the measurement value.

Further, it is also possible to judge the double feeding during document transportation by comparing the data showing the minimum value among the measured values at a plurality of points by the paper thickness measuring sensor 10 with the data at the central portion of the document. In this case, at least the thicknesses of the leading edge portion, the central portion, and the trailing edge portion of the document, which are calculated from the length of the document measured by the paper length detection device 5, are measured, and the minimum value of the measured values of these plural points is measured. The data is compared with the data in the central part, the thickness is measured at three points in each of the leading edge part, the central part and the rear edge part of the document, and the median value of the data measured in each part is measured in each part. The minimum value among the median values at these multiple points is compared with the data at the center of the document, and the thickness is measured at least at four points at each of the document leading edge, the center, and the trailing edge. The maximum and minimum values of the data detected in each part were deleted, the remaining data were averaged in each part, and the averaged minimum and maximum values of the data at the leading edge, center, and trailing edge of the document were averaged. Adopting judgment methods such as comparing with the data in the center of the manuscript Kill.

Next, the operation of detecting a double feed by the document double feed detection apparatus of this embodiment will be described. When the original on the paper feed tray 1 is sent out by the pickup roller 2,
The paper feed roller 3 places a document on the conveyance path 13. At this time, when the originals are fed in duplicate, the separation roller 4 detects this and rotates in the direction opposite to the paper feed roller 3, that is, in the direction opposite to the conveying direction, leaving the uppermost original and feeding the other originals. Return to the paper tray 1 side. However, when the document is double-fed on the conveyance path 13 regardless of the function of the separation roller 4, the document length detection device 5 measures the entire length thereof, and the control / calculation unit measures from the document front end to the document center. Is required. Next, when the document is conveyed to the position of the paper thickness detection device 7, the paper thickness detection device 7 detects the front end of the document, and based on the calculated distance, it is determined that the document is fed to the vicinity of the central position. Start and measure at 3 or 4 points near the center. Here, FIG.
Even when the document is misaligned and is double-fed as shown in (A) or (B), if the measurement is performed in the vicinity of the center of the document, the multi-feed is detected. Then, the measured value is determined by the above method, and the double feed is detected by making a comparison and judgment with the paper thickness stored in advance. Of course, the other determination method described above may be used.

[0024]

As described above, the document double feed detection apparatus according to the present invention detects the thickness near the central portion of the document calculated from the length of the document measured by the paper length detection apparatus. In this case, the measured value is determined as the target for multi-feeding and compared with the standard thickness of the document stored in advance. However, there is an effect that it is possible to properly detect whether or not a multi-feed is made, and the reliability of document transportation of the apparatus is improved.

Since the document double feed detection apparatus according to the second or third aspect measures the thickness of the document at three or four points near the center of the document, the actual document paper due to folds, wrinkles, tears, etc. Since the data different from the thickness can be eliminated, in addition to the effect common to the document double feed detection device according to the first aspect, the reliability of the document conveyance of the device can be further enhanced. There is.

As described above, the document double feed detection apparatus according to the fourth aspect measures the thicknesses at a plurality of points between the measured document leading edge and the document trailing edge, and among the measured values at the plurality of locations. Since the data indicating the minimum value of and the data in the center of the document are compared to determine the double feed during document transport, the actual document thickness due to folds, wrinkles, tears, etc. Different data can be eliminated, accurate paper thickness can be measured, and false double feed detection can be eliminated.

According to the document double feed detecting device of the fifth to seventh aspects, the paper thickness at the front end portion, the central portion and the rear end portion of the document length is measured at each portion, or at least at three or four locations at each portion. According to claim 4, the maximum value and the minimum value of the values measured in each part are deleted, and the remaining respective data are averaged to compare the minimum value and the data in the central part. In addition to the effect common to the document double feed detection device, it is possible to more accurately detect the sheet thickness of the document by the averaging process, and it is possible to more reliably detect the double feed.

As described above, the method of detecting double feeding of an original in the image reading apparatus according to the present invention measures the thickness of the original at the central portion of the conveyed original and at a plurality of positions before and after the original in the conveying direction. The median value of the measured multiple data is taken as the measured value,
Since this is compared with the standard thickness of the document that is stored in advance, the reliability of double-feed detection is improved even when the document is misaligned and double-fed, or when the document edge is folded and conveyed. There is an effect.

As described above, the method of detecting a document double feed in the image reading apparatus according to the ninth aspect is such that at least the thickness of at least the front end portion, the central portion and the rear end portion of the document to be conveyed in the conveying direction is set to at least the respective thicknesses. The data of the minimum value among the measured values at a plurality of points is measured one by one, and the data of the central portion is compared. When the comparison result does not satisfy the predetermined condition, it is determined that the document is multi-fed. There is an effect that the reliability of double feed detection is improved even when the sheets are misaligned and fed, or when the document ends are folded and conveyed.

[Brief description of the drawings]

FIG. 1 is a schematic side view showing the overall configuration of a document double feed detection apparatus according to the present invention.

FIG. 2 is a side sectional view showing a paper thickness measuring sensor which is an example of a paper thickness detecting device.

3A and 3B are diagrams showing different aspects of a document overlapping state.

[Explanation of symbols]

 1 Paper Feed Tray 2 Pickup Roller 3 Paper Feed Roller 4 Separation Roller 5 Paper Length Detection Device 6 Conveyance Roller 7 Paper Thickness Detection Device 8 Image Reading Section 9 Paper Ejection Roller 10 Paper Thickness Measurement Sensor 11 Light Emitting Element 12 Light Receiving Element 13 Conveying Path 14 Original (first sheet) 15 Original (double feed) S1 Optical path when there is no original S2 Optical path when there is one original S3 Optical path when double feed

Claims (9)

[Claims] 1. A paper length detection device for measuring the length of a document to be conveyed in a conveyance direction on a paper conveyance path between a paper feed tray of the image reading device and the image reading section, and the length measurement device. A paper thickness detecting device for measuring the thickness of the original document is arranged, and a storage unit for preliminarily storing the standard thickness of the conveyed original document, the original document thickness stored in the storage unit and the paper thickness detecting device are used. The paper thickness detecting device is provided with a judging means for judging a double feed by comparing the measured values of the manuscript thickness, and the paper thickness detecting device calculates the manuscript length of the manuscript calculated from the length of the manuscript measured by the paper length detecting device. A document double feed detection device for an image reading device, wherein the thickness near the center is detected and used as a determination target measurement value. 2. The paper thickness detection device measures the thickness at three locations near the central portion of the original document calculated from the length of the original document measured by the paper length detection device, and the determination means comprises: 2. The document double feeding detection device for an image reading apparatus according to claim 1, wherein a median value of the measured values is detected and used as a determination target measurement value. 3. The paper thickness detection device measures the thickness at at least four places near the central portion of the document calculated from the length of the document measured by the paper length detection device, and the determination means 2. The document double feed detection apparatus for an image reading apparatus according to claim 1, wherein an average value of data excluding the maximum and minimum values among these measurement values is used as a determination target measurement value. 4. A paper length detecting device for measuring a length of a document to be conveyed in a conveyance direction on a paper conveyance path between a paper feed tray of the image reading device and the image reading section, and the length measurement device. A paper thickness detecting device for measuring the thickness of the original at a plurality of points is arranged, and a judgment means for judging a double feed by comparing a plurality of measured values of the original thickness measured by the paper thickness detecting device is provided. The paper thickness detection device measures the thicknesses at a plurality of points between the front end of the document and the rear end of the document measured by the paper length detection device, and the determination means determines the measured value at the plurality of positions. A document double feed detection device for an image reading apparatus, which compares data showing a minimum value with data in a central portion of a document to determine a double feed during document conveyance. 5. The paper thickness detection device measures at least the thicknesses of the front end portion, the central portion, and the rear end portion of the document, which are calculated from the length of the document measured by the paper length detection device, and the determination means. 5. The document double feed detection device for an image reading apparatus according to claim 4, wherein the minimum value data of the measured values at the plurality of points is compared with the data of the central portion. 6. The paper thickness detecting device determines at least three thicknesses at each of a front end portion, a central portion and a rear end portion of an original document calculated from the length of the original document measured by the paper length detecting device. It is characterized in that the median value of the data measured in each part is used as the measurement value of each part, and the judging means compares the minimum value of the median values of these plural parts with the data of the central part of the document. 5. The document double feeding detection device of the image reading device according to claim 4. 7. The paper thickness detecting device determines at least four thicknesses at each of a front end portion, a central portion, and a rear end portion of a document calculated from the length of the document measured by the paper length detecting device. The determination means deletes the maximum value and the minimum value of the data detected in each of these portions, averages the remaining data in each portion, and averages the leading edge of the original, the center, and the trailing edge. 5. The document double feeding detection device for an image reading apparatus according to claim 4, wherein the minimum value of the data of the set is compared with the averaged data of the center of the document. 8. A standard thickness of an original to be conveyed is stored in advance, and a length of the original to be conveyed in a conveyance direction is on a paper conveyance path between a paper feed tray and an image reading section of the image reading apparatus. Then, the central position of the original in the conveying direction is calculated from the measured length, and the thickness of the original is measured at the central portion of the original including the central position and at a plurality of positions before and after the original in the conveying direction. Using the median value of the measured data as the measurement value, compare the thickness of the stored paper with the thickness of the measured paper.If the measured thickness of the paper is thicker than the stored thickness of the paper, A method for detecting double feeding of an original in an image reading apparatus, which is characterized in that it is judged as a feeding. 9. A thickness of at least a front end portion, a central portion, and a rear end portion of a document to be transported in a transport direction between a paper feed tray of an image reading device and an image reading unit is at least each. Measure one by one and compare the data of the minimum value among the measured values of the above multiple points with the data of the central part,
A method of detecting double feeding of an original in an image reading apparatus, which is characterized in that a double feeding is judged when a comparison result does not satisfy a predetermined condition.