JP2000329510A - Paper thickness detector - Google Patents

Abstract

(57) [Summary] The present invention is less susceptible to the influence of foreign substances such as paper dust present in a paper sheet transport device and environmental changes such as temperature in the device.
Provided are a sheet thickness detecting device and a sheet detecting method capable of detecting the sheet thickness at low cost. An oscillation frequency (f) of an oscillation circuit (11) changes due to a change in an inductance (L) of a coil (10) in which a distance between a ferrite core (9) and a ferrite plate (7) in a displacement detection sensor (8) changes by the thickness of a paper sheet (2). The frequency measurement unit 12 connected to the circuit 11 measures the oscillation frequency f. From the oscillation frequency f0 when there is no paper sheet 2 and the measured oscillation frequency f, the displacement amount of the displacement detection lever 5, that is, the movable roller 4, is calculated,
The thickness of the paper sheet 2 is detected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet thickness detecting apparatus and a sheet detecting method for detecting the thickness of a sheet conveyed on a conveying path by the displacement of a movable roller. The present invention relates to a sheet thickness detecting device and a sheet detecting method for measuring an amount by a change in an oscillation frequency of a coil disposed opposite to a movable roller.

[0002]

2. Description of the Related Art A paper transport device mounted on an automatic teller machine or the like that separates and transports paper sheets such as banknotes and securities one by one has only one transported paper sheet. In order to determine whether or not a foreign substance such as a cellophane tape is attached, a thickness detecting device for detecting the thickness of the paper sheet is provided. In the thickness detecting device, a fixed roller and a movable roller are arranged to face each other across a transport path, and the displacement of the movable roller when the paper sheet is transported is measured by a displacement detection sensor via a lever and the paper sheet is moved. Measuring the thickness of different types.

As a thickness detecting device of such a mechanism, an optical sensor has been used as in a paper sheet thickness detecting device described in JP-A-5-71945. However, there is paper dust and the like generated from the paper sheet inside the paper sheet transport mechanism that transports the paper sheet at high speed, so that the sensor using light is not affected by the paper dust and the like. Measures, for example,
A cover or the like was required, and the mechanism was complicated.

On the other hand, the displacement of the movable roller is determined by using a magnetic displacement detection sensor which is hardly affected by paper dust or the like, such as a sheet thickness detection mechanism described in Japanese Patent Application Laid-Open No. 7-179247. Was detected. In addition, there has been one that detects displacement of a movable roller using a displacement detection sensor based on eddy current.

[0005]

In a paper sheet transporting device mounted on an automatic teller machine or the like installed in a bank or the like, it is determined whether or not a single sheet is being transported by a cellophane tape. Since it is necessary to determine whether or not a foreign substance such as (registered trademark) is attached to the paper sheet, the thickness of the paper sheet being transported is measured by a thickness detection device. The sensor used in the thickness detector must be able to detect the thickness stably without being affected by environmental changes such as the temperature inside the paper transport device or foreign matter such as paper dust present in the paper transport device. Is essential.

However, in the above prior art, the displacement of the movable roller is detected by using a magnetic displacement detection sensor or a displacement detection sensor based on eddy current, so that the influence of foreign matter such as paper dust existing in the paper sheet transporting device is obtained. However, the output of the magnetic sensor and the eddy current sensor is affected by environmental changes such as the temperature inside the paper sheet transporting device. Because of the fluctuation, a circuit for compensating for the fluctuation is also required, so that there is a problem that the thickness detection and detection device becomes expensive.

SUMMARY OF THE INVENTION It is an object of the present invention to reduce the influence of foreign matter such as paper dust present in a paper sheet transport device and environmental changes such as the temperature in the paper sheet transport device, and to reduce the thickness of the paper sheet at low cost. It is an object of the present invention to provide a sheet thickness detecting device capable of detecting a sheet thickness.

[0008]

In order to achieve the above object, in a sheet thickness detecting apparatus for detecting the thickness of a sheet conveyed on a conveying path by displacement of a movable roller, a movable roller is provided. Is characterized by having a coil that is made of a ferromagnetic material and that is arranged to face the displacement detection unit, and an oscillation circuit that is configured by the inductance of the coil and a capacitor and / or a resistor.

Further, the invention is characterized in that the coil and the oscillation circuit are incorporated in a displacement detection sensor.

In a method for detecting the thickness of a sheet conveyed on a conveyance path by the displacement of a movable roller, the displacement detection section of the movable roller is made of a ferromagnetic material.
The displacement of the displacement detector changes the inductance of the coil placed opposite to the displacement detector, changes the oscillation frequency of the oscillation circuit composed of the inductance and the capacitor and / or resistor, and measures the change in the oscillation frequency. The thickness of the paper sheet is detected based on the detected displacement of the displacement detection unit.

Further, the present invention is characterized in that a change in the oscillating frequency of the oscillating circuit is measured at a period of an oscillating waveform.

According to the present invention, the displacement of the movable roller, which moves according to the thickness of the paper sheet, is converted into a change in the inductance of the coil to change the oscillation frequency of the oscillation circuit.
The thickness of the paper sheet can be detected from the change in the oscillation frequency of the oscillation circuit. This eliminates the need for an amplifier, a circuit for temperature compensation, and the like, and can detect the thickness of the sheet with a simple circuit configuration, thereby realizing a small and inexpensive sheet thickness detector. A highly reliable sheet thickness detection method can be realized.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described with reference to embodiments. FIG. 1 is a configuration diagram of a sheet thickness detecting apparatus according to an embodiment to which the present invention is applied. A paper sheet 2 is conveyed on a conveyance path 1 in the direction of an arrow, and a fixed roller 3 and a movable roller 4 are arranged to face each other with the conveyance path 1 interposed therebetween. Movable roller 4
Is connected to a displacement detection lever 5, and a spring 6 is attached to the displacement detection lever 5 so as to bias the movable roller 4 toward the fixed roller 3. A ferrite plate 7 is mounted on the fixed roller 3 side of the displacement detection lever 5 as a displacement detection unit for detecting the displacement of the displacement detection lever 5, that is, the movable roller 4. The sensor 8 is fixed by a method not shown. The displacement detection sensor 8 includes an E-shaped ferrite core 9 and a coil 10.
And an oscillation circuit 11 for detecting the displacement of the ferrite plate 7. The coil 10 attached to the ferrite core 9 is connected to the oscillation circuit 11.

The oscillation circuit 11 is connected to a frequency measuring section 12. A control device (not shown) controls the frequency measurement unit 12.
The thickness of the paper sheet 2 is detected on the basis of the measurement result. The oscillation circuit 11 can be realized by the circuit configuration shown in FIG. This circuit is a Colpitts oscillation circuit described in “Electronic Circuit Science” published by the Institute of Electrical Engineers of Japan. A power supply voltage, for example, −5 V is supplied from the power supply 111.

The inductance L of the coil 10 incorporated in the displacement detection sensor 8 and the capacitance C1 of the first capacitor 112
And the capacitance C2 of the second capacitor 113 is the transistor 1
The first resistor 115 and the second resistor 116 are connected to the base of the transistor 114, and the third resistor 117 is connected to the emitter of the transistor 114. The oscillation frequency f of this circuit is obtained by the square root of 1 / L × (1 / C1 + 1 / C2).

The operation of the apparatus of the embodiment shown in FIG. 1 will now be described with reference to the flowchart of FIG.
Before the sheet 2 reaches the thickness detecting device, a control device (not shown) measures the oscillation frequency f0 of the displacement detection sensor 8 when there is no sheet 2 and stores it as an initial value. In this state, when the paper sheet 2 is conveyed on the conveyance path, the thickness detection processing starts (step 200). When the paper sheet 2 reaches the movable roller 4, the movable roller 4 extends the spring 6, and is displaced in the direction of the arrow by the thickness of the paper sheet 2 (step 201). The displacement detection lever 5 connected to the movable roller 4 is similarly displaced according to the movement of the movable roller 4 (Step 202). The ferrite plate 7 attached to the displacement detection lever 5 is displaced in accordance with the movement of the movable roller 4 like the displacement detection lever 5.

At this time, the ferrite core 9 and the ferrite plate 7 in the displacement detection sensor 8 fixed by means (not shown)
Is changed by the thickness of the paper sheet 2, and the inductance L of the coil 10 is changed (step 203). The change in the inductance L changes the oscillation frequency f of the oscillation circuit 11 (step 204). The frequency measurement unit 12 connected to the oscillation circuit 11 measures the oscillation frequency f (Step 205).

The oscillation frequency f can be measured by measuring the period T of the oscillation waveform as shown in FIG. 4 so that f = 1 / T. The controller calculates the amount of displacement of the displacement detection lever 5, that is, the movable roller 4, from the oscillation frequency f 0 when there is no sheet 2 stored as an initial value and the oscillation frequency f measured in step 205, and The thickness is detected (step 206). At this time, it is also possible to detect whether the thickness of the paper sheet 2 is abnormal by comparing it with the reference thickness of the paper sheet 2.

According to this embodiment, the thickness of the paper sheet 2 is converted into the amount of displacement of the movable roller 4, and the inductance L of the coil 10 is changed according to the displacement of the movable roller 4, and the inductance L is used. Since the thickness of the paper sheet 2 can be detected from the change of the oscillation frequency of the oscillation circuit 11 from the initial value, the thickness of the paper sheet 2 can be detected with a simple configuration.

Since the oscillation circuit 11 is built in the displacement detecting sensor 8, there is an effect that a small-sized thickness detecting device can be realized.

Next, another embodiment of the present invention will be described. FIG. 5 is a diagram showing a ferrite core of a sheet thickness detecting apparatus according to another embodiment to which the present invention is applied. Although not shown, it has the same configuration as that of FIG. 1 except for the ferrite core 90, and has the same function as that of FIG. The ferrite core 90 has a C shape.

According to the present embodiment, since the ferrite core 90 can be reduced in size, there is an effect that a further reduced thickness detector can be realized.

In this embodiment, a Colpitts oscillation circuit is used as the oscillation circuit 11, but the configuration of the oscillation circuit is not limited to this, and another LC oscillation circuit, an LR oscillation circuit, or an LRC oscillation circuit may be used. .

The frequency measuring section 12 of the present embodiment measures the oscillation frequency by measuring the period of the oscillation waveform. However, the present invention is not limited to this, and the oscillation frequency may be obtained by a method using frequency-voltage conversion. Any method may be used as long as it can measure other frequencies. Alternatively, the period may be measured after converting the oscillation waveform into a rectangular wave.

In this embodiment, the inductance of the coil is changed by using the ferrite core and the ferrite plate. However, the present invention is not limited to this, and the inductance of the coil may be changed according to the displacement of the displacement detection unit. For example, a silicon steel plate or the like may be used. Further, the configuration of the displacement detection lever 5 and the spring 6 is not limited to the present embodiment, but may be any configuration that can urge the movable roller 4 toward the fixed roller 3.

In this embodiment, the timing of measuring the oscillation frequency f0 of the displacement detection sensor 8 when there is no paper sheet 2 and storing the oscillation frequency f0 as an initial value is determined at every transaction by an automatic teller machine or the like. It is sufficient that the sheets 2 are not reached the thickness detecting device even every business day.

In this embodiment, the movable roller 4 is always in contact with the fixed roller 3 in the initial state where there are no paper sheets. However, in the initial state, a predetermined set amount, for example, The movable roller 4 may be adjusted so as to be separated from the fixed roller 3 by the reference thickness to detect only the thickness of the paper sheet that is thicker than the reference thickness. Can be detected.

[0028]

According to the present invention, the displacement of the movable roller, which moves according to the thickness of the paper sheet, is converted into a change in the inductance of the coil to change the oscillation frequency of the oscillation circuit. The thickness of the paper sheet can be detected by the change of the paper sheet.Therefore, it is hardly affected by environmental changes such as foreign matter such as paper powder present in the paper sheet conveyance device and the temperature in the paper sheet conveyance device, The thickness of paper sheets can be detected at low cost.

Further, since a circuit such as an amplifier and a temperature compensator is not required and the thickness of the paper sheet can be detected with a simple circuit configuration, the small, inexpensive and highly reliable paper sheet thickness detection is possible. The device can be realized.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a sheet thickness detecting apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing an oscillation circuit of a sheet thickness detecting apparatus according to an embodiment of the present invention.

FIG. 3 is a flowchart illustrating a processing flow of a sheet thickness detecting apparatus according to an embodiment of the present invention.

FIG. 4 is a characteristic diagram showing a method for measuring the oscillation frequency of the oscillation circuit of the sheet thickness detecting apparatus according to one embodiment to which the present invention is applied.

FIG. 5 is a view showing a ferrite core of a sheet thickness detecting apparatus according to another embodiment to which the present invention is applied.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Conveyance path, 3 ... Fixed roller, 4 ... Movable roller, 5 ... Displacement detection lever, 7 ... Ferrite plate, 8 ... Displacement detection sensor, 9, 90 ... Ferrite core, 10 ... Coil, 11 ...
Oscillation circuit, 12: frequency measurement unit, 112: first capacitor, 113: second capacitor, 114: transistor.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Yuji Nagaya 1st Ikegami, Haruoka-cho, Owariasahi-shi, Aichi F-term in the Information Equipment Division, Hitachi, Ltd. 2F063 AA16 BC09 BD17 CA34 DA06 DA21 DD02 EB17 EB25 GA05 GA44 GA45 GA50 LA04 LA30 3E040 AA01 AA05 BA07 DA10 FG14 FL10

Claims (1)

[Claims] 1. A sheet thickness detecting device for detecting the thickness of a sheet conveyed on a conveying path by a displacement of a movable roller, wherein the displacement detecting section of the movable roller is made of a ferromagnetic material.
A sheet thickness detecting device, comprising: a coil disposed to face the displacement detecting unit; and an oscillation circuit including an inductance of the coil and a capacitor and / or a resistor.