JPH0781802A - Method and device for detecting double-feeding of paper sheet - Google Patents

Abstract

PURPOSE:To accurately judge the generation of double-feeding even in the case of thin paper sheets by subtracting a quantity of fluctuation due to the eccentricity of a roller from a quantity of fluctuation as a total of a quantity of fluctuation by a roller and a quantity of fluctuation by paper sheets to extract the pure quantity of fluctuation of only the paper sheets. CONSTITUTION:Quantity of fluctuation due to the eccentricity of a movable roller 4 is previously stored in a table of a detecting means 7, and quantity of fluctuation of only the paper sheet 1 can be measured by subtracting the table data from the output of a time when the sheet 1 is inserted between a fixed roller 3 and a movable roller 4, and double-feeding can be thereby accurately judged.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for detecting the feeding of two sheets of paper and an apparatus therefor, and more particularly to a technique for effectively detecting the feeding of two sheets of thin paper.

[0002]

2. Description of the Related Art Generally, an optical character reading device is provided with a mechanism for detecting two or more sheets when they are overlapped (hereinafter referred to as two-sheet feeding). A method of detecting the double-sheet feeding in the conventional optical character reading device will be described below. As shown in FIG. 3A, the conventional two-sheet feeding detecting device has a rotating roller 2 which rotates in synchronization with a conveying motor on a conveying path of a sheet 1 and a fixed roller 3 which has the rotating roller 2 coaxially. And a movable roller 4 facing and in contact with the fixed roller 3, and a detection mechanism 12 for detecting a variation amount of the movable roller 4. When the paper sheet 1 is inserted between the fixed roller 3 and the movable roller 4, the permissible value of one sheet estimated by the variation amount of the movable roller 4 sampled a plurality of times and the thickness data designated in advance When the variation amount is detected more than the allowable value a plurality of times, it is determined to feed the paper sheet by two.

[0003]

There are a wide variety of paper sheets handled by the optical character reading device, and the thickness thereof also includes a plurality of types. In the above-mentioned conventional technique, for example, when the shaft of the fixed roller is largely distorted, the fixed roller and the movable roller are eccentrically rotated with the rotation of the shaft, and even when there is no sheet between the rollers, it is the same as in the two-sheet feeding. Fluctuations are detected. Particularly when a thin paper sheet is conveyed, the fluctuation amount due to the eccentricity of the roller overlaps the fluctuation amount due to the paper sheet as shown in FIG. There was a problem that it was not possible to correctly judge whether or not two sheets were fed.

It is an object of the present invention to provide a method and apparatus for correctly determining the two-sheet feeding of paper sheets regardless of the distortion of the roller shaft.

[0005]

SUMMARY OF THE INVENTION The present invention has a movable roller that fluctuates according to the thickness of a paper sheet inserted between a fixed roller that is in contact with the fixed roller, and detects the amount of fluctuation. In the method for detecting the two-sheet feeding of paper sheets including a detection means, the eccentricity characteristic of the movable roller is stored in a table in advance, and the paper sheet is inserted between the fixed roller and the movable roller. Two-sheet feeding of the paper sheets is detected based on the relative variation amount obtained by subtracting the stored table data from the variation amount of the movable roller.

Further, the paper sheet two-sheet feeding detecting device of the present invention includes a movable roller that varies according to the thickness of the paper sheet that is inserted between a fixed roller that faces and contacts the movable roller, and the movable roller. A detection unit for detecting the fluctuation amount of the recording medium, and a recording unit for storing the eccentricity characteristic of the movable roller in advance when the paper sheet is absent,
A subtraction unit that subtracts the eccentricity characteristic from a value detected when the paper sheet is inserted between the fixed roller and the movable roller to extract a variation amount of only the paper sheet, and the subtracted variation amount. And a comparison unit that determines whether or not two sheets are fed based on the specified sheet thickness data.

[0007]

Since the fluctuation amount due to the eccentricity of the movable roller can be extracted from the fluctuation amount obtained by combining the fluctuation amount due to the eccentricity of the movable roller and the fluctuation amount due to the paper sheet, the fluctuation amount only for the pure paper sheet can be extracted. Also, even in the conveyance of a thin paper sheet whose change amount is smaller than the variation amount due to eccentricity, it is possible to correctly determine the two-sheet feeding.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram showing an embodiment of the present invention, and FIG. 2 is a diagram showing a state of roller fluctuation and a two-sheet feeding judgment in this embodiment.

As shown in FIG. 1, the construction of this embodiment is such that a rotary roller 2 connected to a motor 6 during conveyance, a fixed roller 3 coaxially rotatable by a bearing, and a fixed roller 3 opposed to and in contact with each other. There is a movable roller 4 between which the paper sheet 1 is inserted. The lever 5 is swingably attached to the rotary shaft of the movable roller 4, and the tip of the lever 5 is rotatably held. A voltage proportional to the rotation angle of the lever 5 is output to the detection means 7 and is A / D converted by the detection unit 8. The detection unit 7 is a detection unit 8 that detects a variation amount of the movable roller 4.
The recording unit 9 that stores the eccentricity characteristic of the movable roller 4 in advance when there is no sheet 1, and the eccentricity characteristic from the value detected when the sheet 1 is inserted between the fixed roller 3 and the movable roller 4. Is subtracted to extract the variation amount of the paper sheet 1 only.
And a comparison unit 11 that determines whether or not two sheets are fed based on the subtracted variation amount and the designated sheet thickness data.

The situation of the double-sheet feeding detection operation of the paper sheets according to this embodiment will be described below. In FIG. 2, waveforms A and C represent the fluctuation amount due to the eccentricity of the movable roller that is assumed from the table sampled when there is no sheet, and waveform B represents the fluctuation amount of the movable roller when feeding one sheet, and waveform D Indicates the amount of fluctuation of the movable roller when feeding two sheets.

(1) Before the paper sheet 1 reaches the movable roller 4, the recording unit 9 samples the eccentricity of the movable roller 4 for one cycle in advance and stores it in the table (waveforms A and C).

(2) When the paper sheet 1 is inserted between the fixed roller 3 and the movable roller 4, the fluctuation amount shows a drastic change (waveforms B and D), and the paper sheet 1 is inserted. The determination is made, and the subtraction unit 10 performs the operation of subtracting the table data from the variation amount.

(3) When two sheets 1 are fed in an overlapping manner and the overlapping portions are inserted between the rollers, the subtracted variation exceeds the allowable value E of the sheet thickness. This is detected by the comparison unit 11, and if the variation exceeds a certain number of times in succession, it is determined that two sheets are fed.

Now, when one thin sheet 1 having a smaller variation than the variation due to the eccentricity of the movable roller 4 is fed, and
Consider the case where multiple sheets are sent in piles. In the case of feeding one sheet, the sampling value shows a change as shown by the waveform B in FIG. The data of FIG. 2B can be obtained by subtracting the variation amount (waveform A) due to the eccentricity of the movable roller 4 that is assumed from the table data from the time when the sheet is inserted. As a result, the data after the subtraction does not exceed the allowable value E even when the eccentricity of the movable roller 4 is large. When two sheets are sent in an overlapping manner, the sampling value shows a change like the waveform D in FIG. 2C, and the data obtained by subtracting the variation amount (waveform C) due to the eccentricity of the movable roller 4 assumed from the table data. FIG. 2D is obtained. When the number of sheets 1 is 1, the allowable value E is not exceeded, but when feeding 2 sheets, as shown in FIG.
It is possible to correctly determine that the two sheets have been fed by exceeding the allowable value E by α as shown by the waveform F of 1.

[0015]

As described above, according to the present invention, the displacement amount due to the eccentricity of the roller when there is no sheet is stored in the table in advance, and this table is output from the output when the sheet is actually inserted. By subtracting the data, it is possible to extract the amount of fluctuation due to only the paper sheets, so even if the roller shaft is distorted or eccentric, it is possible to correctly detect two-sheet feeding even for thin paper sheets that have a smaller change than the roller displacement. The effect is that you can do it.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an embodiment of the present invention.

FIG. 2 is a diagram showing a situation of roller fluctuation and double-sheet feeding determination in the embodiment of the present invention, and FIGS.
In the case of sheet feeding, FIGS. 7C and 7D show the case of feeding 2 sheets, respectively.

3A and 3B are diagrams showing an example of a conventional two-sheet feeding detection method, in which FIG. 3A shows a configuration and FIG. 3B shows a roller fluctuation.

[Explanation of symbols]

 1 Paper Sheet 2 Rotating Roller 3 Fixed Roller 4 Movable Roller 5 Lever 6 Motor 7 Detection Unit 8 Detection Unit 9 Recording Unit 10 Subtraction Unit 11 Comparison Unit 12 Detection Mechanism

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kunio Osawa 1-1, 25-1, Shinurashima-cho, Kanagawa-ku, Yokohama, Kanagawa Prefecture, NEC Electric Robot Engineering Co., Ltd.

Claims (2)

[Claims] 1. A paper sheet having a movable roller that changes according to the thickness of a paper sheet that is inserted between a fixed roller that faces and is in contact with the fixed roller, and a detection unit that detects the amount of the change. Two
In the sheet feeding detection method, a table in which the eccentricity characteristics of the movable roller are stored in advance in a table, and the variation amount of the movable roller that occurs when the sheet is inserted between the fixed roller and the movable roller is stored in the table. A method for detecting double-feeding of a paper sheet, which comprises detecting the double-feeding of the paper sheet from a relative variation amount obtained by subtracting data. 2. A movable roller that varies according to the thickness of a paper sheet that is inserted between a fixed roller that faces and is in contact with the fixed roller,
A detection unit that detects the variation amount of the movable roller, a recording unit that stores in advance the eccentricity characteristic of the movable roller when the paper sheet is absent, and the paper sheet between the fixed roller and the movable roller. A subtraction unit that subtracts the eccentricity characteristic from a value detected when the insertion is performed and extracts a variation amount of only the paper sheet,
A sheet-fed two-sheet feeding detection device, comprising: a comparison unit that determines whether or not two sheets are fed based on the subtracted variation amount and the designated sheet thickness data.