JPH0749950B2 - Thickness detection device for paper sheets - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION In a roller type sheet thickness detecting device, the roller is eccentric by a sufficiently small amount as compared with the thickness of the sheet, and the eccentricity of the roller is Due to the relationship between sensor outputs, we have made it possible to detect the accurate thickness of paper sheets, regardless of sensor sensitivity changes.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thickness detecting device for paper sheets including banknotes.

Conventional technology and its problems The thickness detector, especially the bill thickness detector, is installed in the bill ejector built into the bill handling device such as a deposit payment machine (ATM) or an automatic payment machine (CD). A thickness detection device is used to detect whether or not two or more banknotes delivered from the banknote storage box of the banknote dispenser overlap. By determining whether the thickness of the passing banknote detected by the thickness detection device corresponds to the thickness of one banknote or the thickness of two banknotes, the banknotes are correctly delivered one by one. I know if it is.

The thickness detection device includes a detection roller that is arranged to face an opposed laler provided on a bill conveyance path, and the detection roller is provided on a lever whose base end is pivotally attached.
The lever is biased by a spring in a direction in which the detection roller is in pressure contact with the transport roller. When the bill passes between these two rollers, the detection roller is displaced by the thickness of the bill. This displacement amount is expanded as the displacement amount of the tip portion of the lever. The displacement amount of the lever tip portion is detected by a displacement sensor.

The displacement sensor is composed of, for example, a light emitter and a light receiver which are arranged to face each other with the tip of the lever interposed therebetween. The amount of light received by the light receiver changes in accordance with the amount of displacement by displacing the tip of the lever arranged in the optical path of the projector. Therefore, the output signal of the light receiver represents the thickness of the bill.

The output signal of the photoelectric sensor changes when dust adheres to the projector and the receiver. It also deteriorates over time. Therefore, there is a problem that the displacement / output characteristics change, and the thickness detection accuracy decreases.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a paper sheet thickness detection apparatus capable of maintaining high thickness detection accuracy even if there is a change in displacement / output characteristics due to dust adhesion, deterioration over time, and the like. To do.

The configuration, action and effect of the invention A sheet thickness detecting device according to the present invention constitutes a part of a sheet conveying path, and is attached so as to come into contact with a counter roller which is rotationally driven and a peripheral surface of the counter roller. A thickness signal generator including a biased detection roller and a displacement sensor that outputs an electric signal indicating the amount of displacement of the detection roller, and at least one of the rollers is eccentrically provided, and a paper sheet. Means for detecting the fluctuation range of the output signal of the displacement sensor over a predetermined period when the conveyance roller is not driven between the rollers and the conveyance roller is driven to rotate, Means for detecting the average value of the output signal of the displacement sensor, and correction of the average value of the output signal by using the fluctuation range obtained for the eccentricity of the roller It is characterized in that it is provided with means for obtaining data representing the thickness of the paper sheets that have passed through the space.

When the sheet moves the position of the detection roller, the detection roller is displaced by an amount corresponding to the thickness of the sheet. This displacement amount is detected by the displacement sensor, and a signal representing the displacement amount is output.

On the other hand, even when the paper sheet does not pass between the rollers, the signal output from the displacement sensor shows periodic fluctuations due to the rotation of the eccentric roller. The fluctuation range of this periodic fluctuation of the output signal of the displacement sensor represents the displacement / output characteristic of the displacement sensor. Displacement of the above displacement sensor /
When the output characteristic changes, the fluctuation range changes even though the displacement amount of the eccentric roller is constant. Therefore,
By detecting this fluctuation range, the thickness of the paper sheet represented by the output signal of the displacement sensor can be corrected.

In this way, it is possible to eliminate the influence of the change in the displacement / output characteristics due to the adhesion of dust to the displacement sensor, the deterioration over time, the wear of the roller, and the like. Preferably, an integral multiple of the length of the outer circumference of the eccentric roller is made equal to the length of the paper sheet in the conveying direction. As a result, the adverse effect of the eccentricity of the roller can be eliminated.

Description of Embodiments An embodiment in which the present invention is applied to an apparatus for detecting the thickness of a bill will be described below with reference to the drawings.

FIG. 1 is a schematic view of a mechanical structure of a paper sheet thickness detection device.

In this figure, the conveyance path 1 for the banknotes P is constituted by the upper and lower conveyor belts 9 that are superposed, and the banknotes P are conveyed by being sandwiched between these belts 9. On the way of the conveying path 1, a conveying roller 2 which is eccentric by an eccentricity δ is provided. This eccentricity amount δ is set smaller than the thickness of one banknote P. A groove on which the belt 9 is hooked is formed in the carrying roller 2, and the peripheral surface of the carrying roller 2 is the same as the nipping surface of the belt 9 or protrudes. The transport roller 2 and the transport belt 9 are driven at a transport speed v by a driving device (not shown). The transport roller 2 may be a driven roller.

A detection lever 4 is provided on the shaft 3 above the transport roller 2 so as to be swingable about the shaft 3. The detection lever 4 is L-shaped and has two ends 4a and 4b. A detection roller 5 is rotatably provided in the middle of the detection lever 4 extending in the direction of the end 4b. On the other hand, a tension spring 6 is provided between the end 4 a of the detection lever 4 and the spring receiver 8. As a result, the detection lever 4 is biased by the spring 6 so that the detection roller 5 is brought into pressure contact with the transport roller 2. The detection roller 5 is in contact with the peripheral surface of the transport roller 2 other than the belt 9. The shaft 3, the spring bearing 8, and the mounting member 7a of the displacement sensor 7 described later are fixed to a frame (not shown).

The diameter D of the conveying roller 2 is such that the bill P is so long as 1 in the conveying direction.
Is set so that the following relational expression holds.

l = nπD (n: positive integer) That is, while the bill P passes through the position of the detection roller 5, the transport roller 2 makes n rotations (for example, one rotation).

When the banknote P is sandwiched by the belt 9 and enters between the transport roller 2 and the detection roller 5, the detection roller 5 moves in a direction away from the transport roller 2 by the thickness thereof. As a result, the detection lever 4 also swings as shown by the chain line. Since the detection roller 5 is provided between the end portion 4b and the shaft 3, the displacement amount of the end portion 4b is larger than the displacement amount of the detection roller 5. The detection lever 4 expands the displacement amount.

The displacement sensor 7 detects the amount of displacement of the end 4b of the detection lever 4. This displacement sensor 7 is provided at the end 4b of the detection lever 4.
It is provided with a light projector provided at a position opposed to each other with the light sandwiched therebetween and a light receiver for receiving light from the light projector. When there is no banknote between the transport roller 2 and the detection roller 5,
The optical path of the light emitted from the light projector is hardly blocked by the end 4b of the detection lever 4, and most of the light is received by the light receiver. When one bill enters between the rollers 2 and 5 and the detection lever 4 swings, a part of the optical path is shielded by the displacement of the end 4b. When two bills enter between the rollers 2 and 5, the displacement of the end 4b is doubled, so most of the optical path is shielded by the end 4b, and the amount of light received by the light receiver becomes small. .

FIG. 2 is a block diagram showing an outline of the electrical configuration of the paper sheet thickness detection device.

In this figure, the thickness detection signal S output from the displacement sensor 7 is the A / D converter 10 for each short sampling period.
Is converted into a digital signal by and is taken in by the CPU 11. CPU11
Has a RAM 12 for storing this sampling data.

FIG. 3 shows the displacement / output characteristic of the displacement sensor 7.

In FIG. 3, the horizontal axis represents the displacement amount of the end 4b of the detection lever 4, and the vertical axis represents the value of the thickness detection signal output from the displacement sensor 7 corresponding to the displacement amount (this is referred to as the output value S). ) Is shown. The graph A shown by the solid line in the figure shows the initial characteristics at the time of initial adjustment, and the graph B shown by the broken line shows the characteristics when the characteristics deteriorate due to the displacement sensor 7, throwing dust on the light receiver, aging, etc. Represents each characteristic.

FIG. 4 shows the relationship between the thickness detection signal S output from the displacement sensor 7 and the time T.

In FIG. 4, the horizontal axis represents time T, and the vertical axis represents the thickness detection signal S output from the displacement sensor 7 corresponding to time T. The thickness detection signals in FIGS. 3 and 4 are mutually inverted. Since the banknote P is transported on the transport path 1 at a speed v, it passes through a point of a distance l before the position of the detection roller 5 on the transport path 1 at time l / v (eccentricity measurement period). During this time, the thickness detection signal S output from the displacement sensor 7 repeats a constant cycle of variation due to the eccentricity of the transport roller 2. The transport roller 2 moves n while the bill P passes through the above points.
Since it rotates, the signal S repeats a change of n cycles during the time l / v. In FIG. 4, since n = 1 is set, the transport roller 2 makes one rotation during the eccentricity measurement period, and during this period,
The thickness detection signal S changes for one cycle. Thickness detection signal S
The difference S ₁ between the maximum value and the minimum value of is caused by the eccentricity of the transport roller 2.

Next, the banknote P passes through the positions of the transport roller 2 and the detection roller 5 at the same time l / v (thickness measurement period). At this time, the output signal S of the displacement sensor 7 has a large value, and the transport roller 2 is eccentric, and thus exhibits one cycle of variation as described above. The thickness detection signal S output during this period is integrated (integrated value I _S ) during the thickness measurement period as indicated by the shaded area. This integrated value I _S is measured with the level between the maximum value and the minimum value of the signal S during the above-described eccentricity measurement period taken as the zero level S _o . By dividing this integrated value I _S by the time l / v, the signal value representing the thickness of the bill P = I _S / (l /
v) is obtained.

Both rollers of the banknote P with respect to the rotation angle position of the transport roller 2
The approach timing between 2 and 5 is different. However, the time l / v when the bill P passes through the position of the detection roller 5
Since the transport roller 2 always rotates n times in
If the thickness is the same, the same integrated value is obtained. As a result, the positive and negative errors due to the eccentricity given to the transport roller 2 are almost canceled out, and an averaged value is obtained.

Referring again to FIG. 3, assuming that the displacement / output characteristic of the displacement sensor 7 has linearity, the ratio of the variation S ₁ of the output signal S to the eccentricity amount δ of the eccentric roller 2 and the thickness of the bill P. The ratio of the above average value to t is the same. Therefore, the thickness t of the bill P can be obtained by the following equation.

t = ・ (δ / S ₁ ) = [I _S / (l / v)] ・ (δ / S ₁ ) Thus, even if the characteristics of the displacement sensor 7 are shown by the solid line from the initial characteristic A shown by the broken line Even if there is a change like B, accurate thickness detection can always be performed.

In the eccentricity amount measurement period, for example, a bill detection sensor may be provided at a position in front of the conveyance path by a distance l from the contact points of both rollers 2 and 5, and the time may be measured from the time when the bill is detected by this sensor. The output signal of the displacement sensor 7 is sampled from this bill detection time and the data is stored in the RAM 12
S ₁ can be obtained by storing the sampled data in S and the difference between the maximum value and the minimum value of the stored sampling data. Considering that the bills P may be conveyed in a skewed state, the position of the paper bill detection sensor is better at the front. That is, the distance between both rollers 2 and 5 and this sensor should be 1 or more.

The process of sampling the output signal of the displacement sensor 7 and storing the sampling data is further continued for the next thickness measurement period. During this period, the output signal S rises,
It can be detected by the falling edge. After the output signal s has fallen, that is, after the bill P has passed between the rollers 2 and 5, the value S _o (the above value) representing the above voltage level is sampled from the sampling data stored and sampled during the thickness measurement period. The integrated value I _S can be obtained by subtracting the intermediate value between the maximum value and the minimum value and adding the subtracted data over the thickness measurement period.

There are various integration means other than the addition processing described above. For example, the output S of the displacement sensor 7 is integrated by an integrating circuit over the time period during which the bill P passes through the detection roller 5,
The integrated signal may be A / D converted and taken into the CPU 11. Further, a V / F conversion circuit for converting the thickness detection signal S of the displacement sensor 7 into a pulse signal having a frequency corresponding to the voltage and a counter for counting the output pulse of the V / F conversion circuit are provided, and the bill P It is also possible to operate the counter for a time period during which the light passes through the detection roller 5 and take the count value into the CPU 11. The integration time of the integration circuit and the counting time of the counter can be determined by detecting the rise and fall of the output signal of the displacement sensor 7.

[Brief description of drawings]

FIG. 1 is a schematic view showing a mechanism of a bill thickness detecting device,
FIG. 3 is a block diagram showing its electrical configuration, and FIG. 3 is a graph showing displacement / output characteristics of the displacement sensor. FIG. 4 is a graph showing the relationship between the output of the displacement sensor and time. 1 ... Transport path, 2 ... Transport roller (eccentric roller), 4 ... Detection lever, 4b ... End of detection lever, 5 ... Detection roller, 7 ... Displacement sensor, 11 ... CPU, 12 ... ... RAM, P ... Banknotes.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takashi Hase, Tateishi Electric Co., Ltd., No. 10, Hanazono Dodo-cho, Ukyo-ku, Kyoto City, Kyoto Prefecture (56) References

Claims (4)

[Claims] 1. A counter roller which constitutes a part of a paper sheet conveying path and is rotationally driven, a detection roller which is biased to come into contact with the peripheral surface of the counter roller, and a displacement amount of the detection roller. A thickness signal generator equipped with a displacement sensor that outputs an electric signal, in which at least one of the rollers is eccentrically provided, and there is no paper sheet between the rollers and the transport roller is driven to rotate. Means for detecting the fluctuation range of the output signal of the displacement sensor over a predetermined period while the sheet is passing, a means for detecting the average value of the output signal of the displacement sensor while the paper sheet passes between the rollers, and A means for obtaining data representing the thickness of the paper sheet passing between the rollers by correcting the average value of the output signal using the fluctuation range obtained for the eccentricity of the rollers, A sheet thickness detecting device including. 2. The thickness detecting device for paper elements according to claim 1, wherein the predetermined period is a time required for one sheet of paper to pass through a point on the conveying path. . 3. The opposing roller is eccentric, and an integral multiple of the length of the outer circumference thereof is set equal to the length in the sheet conveying direction. The sheet thickness detection device described. 4. The detection roller is eccentric, and an integral multiple of the length of the outer circumference of the detection roller is set equal to the length in the sheet conveying direction. The sheet thickness detection device described.