JPH01127542A - Detecting method for two-sheet feeding - Google Patents

Abstract

PURPOSE:To surely detect two-sheet feeding by providing a detector which confirms the rear end portion of a sent-out sheet of paper and a detector which is placed on the sending-out end portion of friction member and a feed roller for interposingly holding and sending out the sheet of paper. CONSTITUTION:A detector 15 confirms the rear end portion of a sent-out sheet of paper, while a detector 10 is provided on the sending-out end side of a friction member 7 and a feed roller 6. By confirming the rear end portion of a sent-out sheet of paper by means of the detector 15 and at the point of time when the detector 15 is turned from dark to light, as the detector 10 confirms the next sent-out sheet of paper, i.e., turned dark, judgment is formed to be the occurrence of two-sheet feeding, sending out a two-sheet feeding error signal. Thereby, the danger of two-sheet feeding can be surely avoided. Further, at the time of starting, when the sheet of paper which is to be sent out is in a position that can be detected by the detector 10, judgment is formed equally to above that there is the danger of two-sheet feeding, outputting a two-sheet feeding error signal. Thereby, the occurrence of two-sheet feeding can be completely prevented.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention detects when two or more sheets of paper have been fed in devices that require paper feeding, such as facsimile machines, scanner devices, and optical literature reading devices. The present invention relates to a two-sheet feeding detection method.

[Conventional technology]

There have been various methods (methods) for detecting whether two or more sheets of paper have been sent, but there are generally two main methods. One method is to directly measure the thickness (1) of each sheet of paper by passing a sheet of paper 1 between the light emitting source 2 and the light receiving element 3, as shown in FIGS. 5(a) and 5(b). This is to detect two-sheet feeding. An example of this type of prior art is the one disclosed in Japanese Patent Laid-Open No. 186982/1982. There is also a device that measures the amount of light transmitted through paper sheets without directly measuring the thickness, and detects two-sheet feeding.
It is disclosed in Japanese Patent Application Laid-open No. 89 and Japanese Patent Application Laid-open No. 159768/1989. Another method is as shown in Figures 6(a) and (b).
), measure the length L of the sent paper sheet 1,
A method of detecting two-sheet feed by comparing the unit length Ω has been proposed, and this type of method is disclosed in Japanese Patent Application Laid-Open No. 55-129875.
Examples include those disclosed in the No. 1 gazette.

[Problem that the invention seeks to solve]

In all the methods of the prior art, the thickness (t) of the paper sheet 1
, length CQ') are constant, or the specifications of the sheet 1 are known in advance.

However, in the case of a scanner used in an optical disk file system, etc., the specifications and characteristics of paper sheets are not constant, and paper sheets of different thicknesses, lengths, etc. are often sent in a mixed manner.

On the other hand, when two sheets are fed, the portions where they overlap cannot be read or stored.

Furthermore, in general, in a scanner such as an electronic filing device, a sent paper sheet is always considered to be filed and the paper sheet is discarded. For this reason, there is a problem in that when two sheets of paper are fed, the data evaporates and some parts of the data file are not completely erased. In the prior art, there was no suitable detection method to solve this problem. The present invention solves the above problem, and it is possible to detect paper sheets that are fed in due to differences in specifications such as thickness and length. It is an object of the present invention to provide a two-sheet feeding detection method that can reliably detect two-sheet feeding without any problems and can be easily applied to conventional devices.

[Means for solving problems]

The problem is that the device is equipped with a detector for checking the trailing edge of the fed paper sheet, a friction member that clamps and feeds the paper sheet, and a detector placed on the feeding end side of the friction member of the supply roller. At the point when the detector for checking the trailing edge of the sheet confirms the trailing edge of the sheet being fed out, the detector placed at the feeding end of the friction member detects the trailing edge of the sheet that is being sent out next. If the presence of the sheet is confirmed, it is assumed that two sheets have been fed, and if the detector at the feeding end of the friction member confirms the leading edge of the sheet that is about to be fed when the device is started, then This problem is solved by a two-sheet feeding detection method that assumes that two-sheet feeding has occurred.

[Effect]

When the paper sheets are separated and sent out one by one, other paper sheets are not drawn in and sent out, so the other paper sheets are not on the sending end side of the friction member, that is, they are present inside the friction member. . Therefore, when the previous sheet is fed out, if the next sheet is located near the feeding end of the friction member, it is assumed that two sheets have been fed even if the previous sheet has not actually been fed two sheets. This is to more reliably prevent the occurrence of double-sheet feeding. In addition, if the paper sheet to be fed out is near the feeding end of the friction member when the device is started, the occurrence of double sheet feeding is completely prevented by setting 0 or more, which indicates that there is a risk that double sheet feeding will occur in the future. can do.

(Example) Hereinafter, an example of an apparatus suitable for carrying out the present invention and a detection method will be described with reference to the drawings.

FIG. 1 shows an automatic paper feeding mechanism of a scanner device connected to an electronic file system.

A plurality of types of paper sheets 4 (4a, 4b, 4c, 4d) are stacked on a paper tray 5 at an angle, and are inserted into the gap between the paper feed roller 6 and the friction member 7. The paper feed roller 6 is made of foamed rubber.

The coefficient of friction is greater than the coefficient of friction between the paper sheets 4.

Further, the friction member 7 is supported so as to be able to swing toward the immovable side around a pin 18 so that the lever end side contacts the outer periphery of the paper feed roller 6.
It is constantly pressed against the paper feed roller 6 by the compression spring 8 .

A first detector IO is provided on the delivery end side of the friction member 7 to ensure the presence of the sheet 4 . The first detector 10 is a detector 1 formed by a generating lamp 11 and a receiving element 12.
A pair of drive rollers 14 facing each other on the paper sheet 4 feeding side
is arranged, rotates in the direction of arrow 13, and is formed so that the paper sheet 4 is held between drive rollers 14 and sent out. A second detector 15 for confirming the presence of paper sheet 4 is arranged on the delivery side of the drive roller. The second detector 15 also has a light emitting lamp 1
1' and its light receiving element 12'. Generally, when the second detector 15 confirms the leading edge of the paper sheet 4 that has been sent out, it is assumed that the paper sheet 4 has separated from the paper feed roller 6, and the feeding force of the rotating paper feed roller 6 is cut off. . however,
A one-way clutch bearing is attached to the paper feed roller 6, so that it can rotate freely in nine directions as seen by the arrow.

Next, the detection method in the above device will be explained in more detail.

As shown in FIG. 1, the sheets 4a, 4b, 4c, and 4d are stacked and the sheet tray is mounted on the table 5, with the sheet 4a at the bottom and the sheets 4b, 4c, and 4d sequentially placed on top of each other. This is because the table 5 of the paper tray 1, which is arranged in this order, is tilted.

As shown in the figure, the paper sheets 4b, 4c, etc. may be held between the paper feed roller 6 and the friction member 7 at a position farther forward than the paper sheet 4a in the feeding direction. However, as described above, the frictional force between the paper feed roller 6 and the paper sheet 4a is greater than the frictional force between the paper sheets 4, such as the paper sheet 4a and the paper sheet 4b, so that when the paper feed roller 6 rotates, the paper sheet 4a is sent out by the paper feed roller 6, moves between the friction member 7 and the paper feed roller 6 while compressing the compression spring 8, is held between the drive rollers 14, and is sent out. When the second detector 15 detects the leading end of the sheet 4a, the feeding force of the sheet feeding roller 6 is cut off and the sheet 4a is freely drawn out by the driving roller 14, as described above.

A case where two sheets are fed in the above feeding process will be described. As shown in FIG. 2(a), two-sheet feeding occurs and the paper sheets 4a and 4b are sent out overlapping each other.
If sheet feeding is not detected, but two-sheet feeding occurs as described above, the sheet 4c on top of one sheet 4b is dragged by the feeding of sheet 4b and becomes larger than necessary, as shown in FIG. 2(b). In many cases, it advances to the vicinity of the sending end of the friction member 7.
That is, in this embodiment, where the presence of the paper sheet 4c is confirmed by the first detector lO, as shown in the detection logic diagram of FIG.
The second detector 15 confirms the rear end of the paper sheet (sheet 4b in the above case) that has been sent out, and the second detector 15 changes from clear to bright, and the first When the detector 10 confirms the next paper sheet to be sent out (4c in the above case), that is, when it becomes dark, it is assumed that two sheets have been fed.
It is designed to send out a sheet feed error signal. Therefore, even if one sheet 4a is fed with one sheet 4a and 4b overlapping each other as shown in FIG. 2 if a sheet of paper (e.g. 4b) is identified by the first detector lO.
A two-sheet feeding error signal is generated assuming that the sheet has been fed. This makes it possible to reliably avoid the danger of feeding two sheets. Furthermore, as shown in FIGS. 3(a) and 3(b), if the 3114th
As shown in (b), the paper leaf 4c that will be offered from now on
However, when the position is detected by the first detector IO, a two-sheet feeding error signal is generated because there is a risk that two-sheet feeding will occur, as in the case described above. The AND circuits 16 and 17 in FIG. 4 perform the above signal processing, and these signals are configured to issue a two-sheet feeding error signal via the OR circuit 19.

〔Effect of the invention〕

According to the present invention, this is carried out regardless of the specifications such as the thickness and length of the paper sheet, and the effect of reliably preventing double-sheet feeding can be achieved. Furthermore, one or more of the methods are readily applicable to scanner devices, facsimile devices, etc., and do not require complex device implementations as in the prior art.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of an apparatus to which an embodiment of the present invention is applied;
Figure 2 (a), (b) and Figure 3 (a), (b)
is an explanatory diagram of the action, FIG. 4 is a detection logic diagram, and FIG. 5(a). 6(b) and FIGS. 6(a) and 6(b) are explanatory diagrams for explaining the conventional two-sheet feed detection method. 1.4, 4a, 4b, 4c, 4d - paper leaf, 2.11゜11'... light emitting source, 3.12.12'... light receiving element, 5... paper leaf holder is stand, 6 ...Paper feed roller, 7...
- Friction member, 8... Compression spring, IO... First detector, 14... Drive roller, 15... Second detection I1
．． 16.17...AND circuit, 18...pin. 19...OR circuit. Representative Patent Attorney Tadashi Akimoto Minoru No. 3 Question 16---Aya J!槓17---article e1 redemption 19---Sua! Iil Rei Figure 4 Figure 5 Leap (a) (b) Figure 6 (a) (b) 1---Ichidaiso 2・-Elichiso light source 3-Ichiichido fJ Munezi

Claims (1)

[Claims] 1. In a paper supply device configured to sandwich a plurality of paper sheets between a friction member having a coefficient of friction higher than that between sheets and a paper supply roller having a coefficient of friction slightly higher than this and sequentially feed the sheets one by one. In the two-sheet feed detection method, a detector that confirms the rear end of the fed paper sheet emits a passing signal of the paper sheet, and a detector that is disposed at the feeding end of the friction member when the paper sheet passes. when the sensor at the feeding end of the friction member issues a signal to confirm the leading edge of the next paper sheet to be fed out, and when the device is started, the detector at the feeding end of the friction member issues a signal to check the leading edge of the paper sheet to be fed out. A two-sheet feeding detection method that determines that two-sheet feeding has occurred only when