JPH0721438A - Paper sheet detecting device - Google Patents

Abstract

PURPOSE:To provide a paper sheet detecting device capable of detecting the outside dimension of each paper sheet by using a CCD image sensor easily generating saturation. CONSTITUTION:This paper sheet detecting device is provided with an image sensor 4 for receiving light outputted from a light source 1 to irradiate a paper sheet 2, a binarizing circuit 8 for converting an output from the sensor 4 into a binarized picture element bit value, a counter circuit 9 for counting up the picture element bit value binarized by the circuit 8, a light quantity control circuit for controlling the light quantity of the light source 1, and a main control circuit 10 for controlling these circuits. The circuit 10 inputs the transition of count values at the time of shifting the light quantity of the light source 1 from small to large or large to small in the absence state of a paper sheet 2 and sets up the light quantity of a range having a small change out of the transition of the count values in the circuit 5, so that a paper sheet can be detected by using the light quantity of a range in which the saturation of the sensor 4 does not occur.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paper sheet detecting apparatus for optically detecting a paper sheet, and more particularly to a paper sheet detecting apparatus which can use an image sensor in which a light receiving portion is likely to be saturated.

[0002]

2. Description of the Related Art Generally, a paper sheet detecting device used in a bill discriminating device in an ATM, a paper sheet counting machine or the like optically detects a size / breakage / folding of a paper sheet. The image sensor used for detection needs to simultaneously detect a strong light amount in a portion without a sheet and a weak light amount in a portion in which a sheet is likely to be saturated in the light receiving portion.

For example, when an amorphous image sensor is used as an image sensor as this sensor, even if saturation occurs in a specific light receiving portion due to the strength of a light source, it is difficult to affect other light receiving portions, and therefore, the above-mentioned object is achieved. Suitable but C
Since it is more expensive than a CD image sensor or the like, there is a disadvantage that the cost of the device is increased.

For this reason, the CCD image sensor is generally used for detecting reflected light which is sufficiently prevented from being saturated, as in a facsimile, an OCR, and an image scanner.
The amorphous image sensor or the like is often used to detect the size of the paper sheet by the transmitted light. Documents describing the technology relating to the paper sheet detection device include, for example, JP-A-58-223890 and JP-A-58-86681.

[0005]

When the CCD image sensor is applied to a paper sheet detecting device, the CCD image sensor has a characteristic of causing saturation when a light amount exceeding a specified amount is applied to the light receiving portion. Is not limited to only the light-receiving portion that receives a prescribed amount of light, but the output of the CCD image sensor chip as a whole is abnormal, and the output is larger than the number of pixels of the light-receiving portion physically provided in the image sensor. There is a problem that it cannot be used in the paper sheet detection device because the phenomenon or in a remarkable case, the whole output of the CCD image sensor rises. In particular, when the CCD image sensor is used for detecting the size of the paper sheet, the amount of light in the area without the paper sheet becomes large, so that the sensor output more than the number of pixels of the light receiving section appears unstable due to the occurrence of saturation, and the detection is performed. There was a problem that became impossible.

An object of the present invention is to eliminate the above-mentioned problems caused by the prior art, and to provide a paper sheet detecting device capable of detecting a paper sheet by transmitted light through a CCD image sensor.

[0007]

In order to achieve the above-mentioned object, the present invention irradiates light from a light source onto a paper sheet, and an image sensor receives the light radiated onto the paper sheet to form an outer shape of the paper sheet. In a paper sheet detection device for detecting, a light source for irradiating light onto a paper sheet, an image sensor for receiving light intercepted by the paper sheet and light not intercepted from the light source, and an output of the image sensor are binarized. A binarization circuit for converting the pixel bit value, a counter circuit for counting the pixel bit value binarized by the binarization circuit at a predetermined slice level, a light amount control circuit for controlling the light amount of the light source, A main control circuit for controlling each circuit is provided, and the light amount control circuit changes the light amount of the light source from small to large and / or large to small in a state where the main control circuit does not have a sheet, and the count value transition at the time of this transition And input The light amount in the range where the transition is small in the transition of the input value is set in the light amount control circuit to detect the paper sheet, and thus the paper amount is detected using the light amount in the range where the image sensor does not saturate. .

[0008]

In the paper sheet detecting apparatus according to the present invention, the transition of the count value when the light quantity control circuit shifts the light quantity of the light source from small to large and / or large to small in the state where the main control circuit has no paper sheet is inputted. The saturation of the image sensor is prevented by setting the quantity of light in the range where the transition is small in the transition of the count value in the light quantity control circuit, and the abnormal output due to the saturation of the CCD image sensor output makes it impossible to detect the sheet. Can be prevented. As a result, it is possible to accurately detect the size, breakage and crease of the paper sheet based on the size and the number of bits of the light receiving portion of the original image sensor.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A paper sheet detecting apparatus according to an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a conceptual diagram showing the overall configuration of the paper sheet detection apparatus according to this embodiment, FIG. 2 is a diagram showing the output timing of a CCD image sensor, and FIG. 3 is a diagram showing changes in the output level of the CCD image sensor.

First, as shown in FIG. 1, the paper sheet detecting apparatus according to the present embodiment collects the light source 1 for generating light for detecting the width of the paper sheet 2 and the light passing through the paper sheet 2. Lens 3
And an image sensor 4 that receives light from the lens 3.
An amplifier circuit 7 for amplifying an electric signal received by the image sensor 4, a binarization circuit 8 for converting the output of the amplifier circuit 7 into a pixel bit value which is a digital signal, and the binarization circuit 8. Of the binarized pixel bit values,
A counter circuit 9 for counting pixel bit values equal to or higher than a predetermined slice level, an image sensor control circuit 6 for controlling the light receiving level of the image sensor 4, a light amount control circuit 5 for controlling the light emission amount of the light source 1, and these. And an overall control circuit 10 for controlling the
The pixel circuit outputs the outer shape of the paper sheet 2 by irradiating the sheet 2 through the amplifier circuit 2 and binarized by the binarizing circuit 8 to detect the pixel bit value output by the counter circuit 9 counting at a predetermined slice level. ing. The image sensor 4 according to this embodiment is composed of a CCD image sensor.

The output of the binarization circuit 8 changes depending on the amount of light from the light source 1. For example, when the amount of light is appropriate without the paper sheet 2, as shown in FIG. Although the pixel bits that have reached the binarization level are binarized, when the light amount is excessive, side-out pixel bits b ₁ and b ₂ due to saturation occur at the right end as shown in FIG. If the number is insufficient, pixel bits b ₃ and b ₄ that do not reach the binarization level are generated at the left end as shown in FIG. That is, the CDD image sensor has a characteristic that the binarized pixel bit value changes depending on the light amount of the light source 1 and a dimensional error of the paper sheet 2 occurs.

The overall control circuit 10 according to this embodiment is shown in FIG.
As shown in FIG. 4, the light amount control circuit 5 is controlled prior to the sheet detection to control the light amount of the light source 1 from a small light amount to a large light amount, and a control for shifting from the large light amount to the small light amount again is performed, and the binarization circuit 8 in the meantime. 3 is counted at a predetermined slice level, and it is determined that the light quantity at which the number of counters in FIG. 3 is relatively horizontal is within the proper range of the light quantity, and the light quantity L ₁ during this period is
Approximately ⅓ of the maximum value of L ₂ to L ₂ (indicated by P in the figure) is recognized as an appropriate light amount of the light source 1, and the value is set in the light amount control circuit 5. Amount indicated by the point P, since than was used to level L ₁ or L ₂ is unstable, it is sufficient and select proper point near the L ₂ between L ₁ and L _2, for example, the amount of light The amount of light may be about 1/4 from the maximum value of L _{1 to} L ₂ . Further, the light amount control for obtaining the appropriate light amount may be configured such that the light amount is controlled from a large light amount to a small light amount or the light amount is recognized a plurality of times.

In the paper sheet detection apparatus, the main control circuit 10 determines the above-mentioned proper light quantity before starting the apparatus, and instructs the light quantity control circuit 5 to indicate the proper light quantity, and then conveys the paper sheet 2 to the light source 1.
The image sensor 4 detects the amount of light of the paper sheet 2 passing through the light source 1 via the lens 3, and the amplifier circuit 7 based on this amount of light.
The counter circuit 9 counts the count value when the binarization circuit 8 passes through the paper via the counter, so that the outer dimension of the paper sheet 2 can be detected while preventing the image sensor 4 from being saturated. The counting by the counter circuit 9 is performed by calculating the interval between the counter value before the paper sheet 2 passes and the count value after the paper sheet passage 2 using the transport speed of the paper sheet 2 as a factor, and thereby the outer shape of the paper sheet 2 is calculated. By detecting the size, the size and breakage can be detected. As described above, the paper sheet detection apparatus according to the present embodiment detects the saturation range of the image mentor 4 using the CCD before starting the apparatus,
Margin for saturation for image sensor 4 (P>
It is possible to detect the outer dimensions of the paper sheet by using an appropriate light amount that maintains L ₂ ). It should be noted that the range L _{1 to} L ₂ in the light amount shown in FIG. 3 is shown horizontally, but the actual shift in the number of counters increases, for example, with a minute angle θ ₁ , and when the light amount becomes L ₂ or more. The detection points L ₁ and L ₂ are changed so as to increase to a relatively large angle θ ₂ (θ ₂ > θ ₁ ).
The determination is based on the angle change.

[0014]

As described above, the paper sheet detection apparatus according to the present invention counts when the light quantity control circuit shifts the light quantity of the light source from small to large and / or large to small in the state where the main control circuit has no paper sheet. By inputting the transition of the value and setting the light amount in the range of the transition of the count value with less transition in the light amount control circuit, the saturation of the image sensor is prevented, and the abnormal output due to the saturation of the output of the CCD image sensor Undetectable leaves can be prevented. This is the original image
It is possible to accurately detect the size, breakage, and crease of a paper sheet based on the size and the number of bits of the light receiving portion of the di-sensor.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of the overall configuration of a paper sheet detection apparatus according to the present invention.

FIG. 2 is a diagram showing an output timing of a CCD image sensor due to a difference in light amount.

FIG. 3 is a diagram showing a change in the number of output bits of a CCD image sensor when binarization is performed due to a difference in light amount.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Light source, 2 ... Paper sheet, 3 ... Lens, 4 ... Image sensor, 5 ... Light amount control circuit, 6 ... Image sensor control circuit,
7 ... Amplifier circuit, 8 ... Binarization circuit, 9 ... Counter circuit,
10 ... Control circuit.

Claims (1)

[Claims] 1. A paper sheet detecting device for detecting the outer shape of a paper sheet by irradiating the paper sheet with light from a light source and receiving the light with which the paper sheet is irradiated with light. Light source, an image sensor for receiving the light intercepted by the sheet from the light source and the light not intercepted by the paper sheet, and the output of the image sensor is converted into a binarized pixel bit value 2
A binarizing circuit, and a counter circuit for counting the pixel bit value binarized by the binarizing circuit at a predetermined slice level,
A light amount control circuit for controlling the light amount of the light source, and a main control circuit for controlling each circuit are provided, and the light amount control circuit controls the light amount of the light source from small to large and / or large in a state where the main control circuit has no paper sheet. When the transition to the small value is made, the transition of the count value at the time of this transition is input, and the light amount in the range where the transition is small among the transitions of the count value is set in the light amount control circuit to detect the sheet, thereby detecting the saturation of the image sensor. A paper sheet detection apparatus, which detects a paper sheet by using a light amount in a range that does not occur.