JPS5939645A - Duplicate feed detection device - Google Patents

Abstract

PURPOSE:To reliably detect a duplicate feed even for various sheets with different light permeability factors by detecting a duplicate feed of the sheets by means of the permeating light of the sheets and making the detection sensitivity selectable in a device transporting the sheets. CONSTITUTION:Light rays are illuminated from a light emitter 2 to a sheet 1 transported by a roller, etc., its permeating light is detected by a photosensor 3, amplified by an amplifier 6, then compared with a reference level V0 for detecting a duplicate feed from a reference level generator 7 at a comparator circuit 8 to generate a detection signal 9. The emitted light quantity of the light emitter 2 is adjusted by selecting either of power supplies 4-1-4-n with a selection switch, for example, to change the power supply to be fed. Thereby, the emitted light quantity of the light emitter 2 is changed according to different light permiability factors depending on the quality and thickness, etc. of the sheets 1, thus the light emitter 2 emits light rays at a luminous level not causing the miss detection of a duplicate feed. Therefore, a duplicate feed can be reliably detected.

Description

Detailed Description of the Invention (1) Technical Field The present invention relates to a device for detecting double feeding of paper sheets in an apparatus for conveying paper sheets such as paper. In a device having a conveyance section for conveying paper sheets (hereinafter referred to as paper) such as beam printers and copying machines5,
There are devices that detect double feeding of paper and control each part of the device.

As a device for detecting this double feed, there is one that detects double feed by using a pair of light emitting part and light receiving part17, and detecting the light transmitted through the paper by irradiating the paper with light1. In the feeding detection device, the light emission intensity of the light emitting section is constant, the amplification factor of the signal from the light receiving section is constant, and the basic signal level for determining double feeding is constant. Therefore, such double feed detection [11] is effective only for a specific type of paper, and has the disadvantage that false detection occurs when the material, thickness, etc. of the paper changes.

ω]) Purpose The present invention aims to eliminate the above-mentioned drawbacks and provide a double-feed detection device that can reliably detect double-feed for various types of paper.

Another object of the present invention is to provide a double feed detection device in which the sensitivity of the double feed detection means can be selected. .

OV) Example Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 shows a first embodiment of the invention. 1 is a paper conveyed by a conveying means (not shown); 2 is a light emitter that irradiates light onto the paper 1 to detect double feeding; 61 is a light receiver for detecting light from the light emitter 2; 4-1 ~4-n is a power supply for supplying various kinds of power to the light emitter B, 5 is a selection switch for selecting power supplies 4-1 to 4-n, and 6 is a power supply for amplifying the entire signal from the light receiver Roga. An amplifier, 7 is a reference level generating section that generates a reference level o for double feed detection, 8 is a receiver, which compares the signal outputted through the amplifier 6 with the reference level and outputs a detection signal 9. This is a comparison circuit that

Light is irradiated from a light emitting section 2 onto the paper 1 being conveyed by a conveying section consisting of rollers, belts, etc. This transmitted light is detected by a light receiver 5, amplified by an amplifier 6, and then compared with a reference level vo by a comparator circuit 8.

The amount of light emitted by the light emitter 20 changes depending on the power supplied. In the above embodiment, the selection switch 5 selects the power supplies 4-81 to 4.
Since power can be supplied to the light emitting device 2 by selecting the lower one of −n, users, Levismen, etc. can
It is possible to select the power source according to the light transmittance determined by the thickness, etc., change the light emission 1- of the light emitter 20, and cause the light emitter 2 to emit light at a light emission level that does not cause false detection of double feeding.

Note that when selecting the light emission intensity of the light emitter 2, the light emitter is
If it is composed of EDs, etc., it may be configured as a column that selects the current flowing through the LEDs (・.

FIG. 2 shows a second embodiment of the invention. In this example, the power supplied to the light emitter 2 is fixed, and the reference level for double feed detection can be selected. In the figures, the same numbers as in Figure 1 refer to "same component parts", 14
is a power source that supplies power to the light emitter 2, 17-1 to 17-n
is a reference level generating section which generates reference level signals 1 to vrL for detecting double feed. With the above configuration,
By selecting the reference level input to the comparator circuit 8 using the selection switch 5 according to the transmittance of the paper, it is possible to prevent false detection of double feeding.

Further, FIG. 3 shows a third embodiment of the present invention. In this example, the configuration is such that the amplifier that amplifies the detection signal of the transmitted light from the light receiver 3 can be selected. There is a diagram. Since the configuration is as described above, erroneous detection of double feeding can be prevented by selecting either the increase 6s' or the 3 degrees Celsius or 3 degrees Fahrenheit with the selection switch 5 according to the paper transmittance. becomes possible.

Although the selection of the sensitivity in the second embodiment is performed manually by the user, Levisgon, etc., it may be configured to be performed automatically.

FIG. 4 shows an example of automatically selecting this sensitivity. In the figure, the same parts as in Figure 1 are the same components, 11tJ, a light emitter with a certain predetermined position, 12 is a light receiver that receives light from the light emitter 11, and dust 16 is a photosensitive This is a control unit that determines double feeding according to the switching and the switched sensitivity. This control unit 13 is composed of a CPU constituted by a well-known microcontroller, etc.
This includes the parts of the double feed detection device shown in FIG. 6, excluding the light emitter 2 and light receiver.

In this example, before double feed detection is performed by the light emitting rod 2 and the light receiver 6, the light transmitted by the paper 1 is divided into one light by the light emitter 11 and the light receiver 12.
Based on this sampling signal 14, the cPU in the control unit 13 switches the selection switch 5 to select the sensitivity. Then, transmission is detected in step 3 with the sensitivity selected by the signal from the light receiver 6.

(V) Effects As described above, according to the present invention, the sensitivity for detecting double feeding can be selected, so double feeding can be reliably detected even for papers with different light transmittances.

Moreover, by configuring the column to automatically select the sensitivity, it becomes possible to use different types of paper at the same time.

[Brief explanation of the drawing]

1! Figure 1 is a block diagram showing an example in which the emission intensity is selected, Figure 2 is a block diagram showing an example in which the reference level is selected, and Figure 3 is an example in which the amplification factor is selected. FIG. 4 is a block diagram showing an embodiment in which automatic sensitivity selection is performed. In the figure, 2 and 11 are light emitters, 6 and 12 are light receivers, and 4
-1 to 4-4.14 is the power supply, 5 is the selection switch, 6,
1<5-1 to 16-n are amplifiers, 7.17-1 to 17-
-- is a reference level generating section and an 8kl comparison circuit. Applicant Canon Co., Ltd.

Claims (1)

[Claims] A double feed detection device for conveying paper sheets, which includes a detection means for detecting double feeding of paper sheets using transmitted light of the paper sheets, and a selection means for selecting the sensitivity of the detection means.