JPH11120403A - Identification device - Google Patents

Abstract

(57) [Summary] (with correction) [PROBLEMS] To provide a device capable of performing high-precision correction for temperature drift, aging, and the like of a light-emitting and light-receiving element, and accurately discriminating the authenticity of a valuable medium. SOLUTION: A first contact that outputs a change in resistance of a light receiver 5 as a change in voltage, and has an input terminal to supply a current to the light emitter and change a current value to be supplied according to the voltage of the input terminal. A current supply circuit, a predetermined reference voltage 9 and a first
An operational amplifier 1 that amplifies and outputs the output voltage of the contact and outputs
Before the measurement of the received light data, the output of the operational amplifier is fed back to the input terminal of the current supply circuit, and the first switch means 2 cuts off the feedback at the time of measuring the received light data; before and after the first switch means cuts off the feedback. And a voltage holding means 3 for holding the voltage of the input terminal of the current supply circuit constant.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an identification device for identifying an object such as a bill by reflected light or transmitted light.

[0002]

2. Description of the Related Art In a conventional discriminating apparatus (for example, a discriminating apparatus for discriminating bills), light is emitted from a light emitting device (light source) to bills to be conveyed, and reflected light or transmitted light is received by an optical sensor. While collecting the discrimination data (identification data, discrimination data, judgment data), the light reception data of a legitimate bill is collected in advance as standard data, and the discrimination of the bill is performed by comparing the discrimination data with the standard data. Is going.

The discrimination function of the apparatus is determined by collecting the discrimination data under the same conditions as when collecting the standard data, or normalizing the collected data so as to be the same as that collected under the same conditions. . However, since the output of the discrimination data is fluctuated due to fluctuations in the light intensity of the light emitter, disturbances such as external temperature, etc., these fluctuation elements are eliminated and the optical sensor output (light receiving sensor) is collected under the same conditions as the standard data. Output data is corrected.

For example, a method of reading the temperature as an analog signal with a temperature reading sensor arranged near the output of an optical sensor or the output of a light receiving sensor and directly inputting the read analog signal to an operational amplifier, or correcting the temperature of the thermistor. There is a method of performing temperature correction using such a method, or a method of A / D converting an analog signal of a light receiving sensor output and correcting the analog signal by software processing.

[0005]

However, the above-described method of correcting measurement data using a temperature reading sensor or a thermistor considers only temperature drift correction, and does not consider aging. Further, a method of correcting the temperature with a thermistor is practically impossible because the temperature characteristics of the light receiving and light emitting elements and the thermistor must be the same.

[0006] Also, due to the characteristics of the semiconductor, the brightness of the LED decreases as the temperature rises, while the light receiving sensitivity of the phototransistor increases as the temperature rises. Since the temperature characteristics of these light receiving and light emitting elements both change to a higher order with respect to the temperature, they cannot be centrally corrected. Since there are two parameters that cannot be corrected centrally, correction by the above software processing is practically impossible.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem, and is an identification device capable of performing high-precision correction for temperature drift, aging, and the like, and capable of accurately identifying the authenticity of an object to be identified. The purpose is to provide.

[0008]

In order to solve the above-mentioned problems, the invention according to claim 1 changes a light emitting amount according to a current amount, and changes a predetermined physical characteristic according to a light receiving amount. A discriminating device comprising: a light receiver; measuring light reception data of reflected light or transmitted light of the identification object by emitting light of the light emitter and receiving light of the light receiver; and identifying the identification object based on the received light data. And a first contact that outputs a change in physical characteristics of the light receiver as a change in a predetermined amount of electricity,
A feedback unit that feeds back the amount of electricity at the first contact and adjusts the amount of current flowing through the light emitting device to correct the amount of electricity output to the first contact to a predetermined value; While the amount of electricity at the first contact is fed back to the correction means,
A configuration comprising: first switch means for cutting off the feedback at the time of measuring the light receiving data; and holding means for holding a constant amount of current flowing to the light emitter before and after the first switch means cuts off the feedback. And

According to the first aspect of the invention, after the first switch is turned on before measuring the received light data, the first switch is turned off when measuring the received light data, so that the light is emitted before the measurement. The light emitting state of the light emitting device is corrected and the predetermined amount of electricity at the first contact becomes a predetermined value. Thereafter, the light emitting device is held in the corrected state by the holding means, and the light receiving data is measured. That is, it is possible to measure the received light data in a state where the temperature drift, the aging, and the like are corrected with high accuracy.

Here, the object to be identified is, for example, a valuable medium such as a bill, a check, a bill, a securities, a stamp, a license, a passport, or the like. The light emitter, for example,
Light guide lasers, light emitting diodes, solid lasers, various light bulbs and the like can be used. As the light receiver, for example, a photodiode, a phototransistor, or the like can be used, and the physical characteristics are an electromotive force in the case of a photodiode and a resistance in the case of a photodiode. The amount of electricity output to the first contact is, for example, a voltage, but may be a current, a pulse signal, or the like.

According to a second aspect of the present invention, there is provided a light emitting device for changing a light emitting amount according to a current amount, and a light receiving device for changing a resistance value as the predetermined physical characteristic according to a light receiving amount. And an identification device that measures light reception data of reflected light or transmitted light of the object by receiving light from the light receiver, and identifies the object based on the light reception data, wherein the resistance of the light receiver changes. And a current contact circuit having an input terminal for supplying a current to the light emitting device and changing a current value to be supplied according to the voltage of the input terminal. And an operational amplifier that amplifies and amplifies a predetermined reference voltage and the output voltage of the first contact, and outputs an output of the operational amplifier to an input terminal of the current supply circuit before measuring the light reception data. The receiving A configuration comprising: first switch means for cutting off the feedback at the time of data measurement; and voltage holding means for holding the voltage of the input terminal of the current supply circuit constant before and after the first switch means cuts off the feedback. And

According to the second aspect of the present invention, when the first switch is in the ON state, the output voltage of the first contact is arithmetically amplified with a predetermined reference voltage and is fed back to the input terminal of the current supply circuit. Therefore, the voltage of each contact in the circuit is a voltage based on the reference voltage. In other words, since the first contact is connected to the other input terminal of the operational amplifier circuit, the output voltage becomes the voltage determined by the reference voltage, and the characteristics of the light emitting device and the light receiving device change due to temperature and aging. Does not displace at all. That is, by turning on the first switch means, the light emitting state of the light emitting device is corrected so that the potential of the first contact becomes a fixed value.

On the other hand, when the first switch means is in the off state, the feedback of the output voltage of the first contact through the operational amplifier is cut off, the circuit between the light receiving device side and the light emitting device side is cut off, and the light receiving amount is changed according to the light receiving amount. Since the potential of the second contact changes, the light reception of the light emitting device is received by the light receiving device via the object to be identified, as in the related art, so that the measurement of the received light data can be performed by the change in the potential of the second contact and the like. I can do it.

Further, at the stage when the first switch means is switched from on to off, the holding means holds the input voltage of the current supply circuit, so that the value of the current flowing through the light emitting device is maintained at the value at the time of the correction. After that, the light emitting state of the light emitting device maintains the state at the time of correction. Therefore, the output voltage of the first contact at the switching stage is
This is a fixed value at the time of the above correction.

[0015] From the above, the first light reception data measurement is performed.
After the switch is turned on, the output voltage of the first contact is corrected to a fixed value before the measurement by correcting the first switch to an off state when measuring the received light data (the light emitting state of the light emitter is corrected). In this corrected state, measurement of the received light data can be performed. That is, it is possible to measure the received light data in a state where the temperature drift, the aging, and the like are corrected with high accuracy.

According to a third aspect of the present invention, in the identification device according to the first or second aspect, the correspondence between the value of the physical characteristic of the light receiver and the value of the electric quantity output to the first contact is changed. A configuration is provided that includes a possible changing unit and a second switch unit that switches the correspondence by operating the changing unit depending on whether or not the object is present at the measurement position of the received light data.

For example, whether the form of measuring the received light data uses reflected light or transmitted light,
The amount of light applied to the light receiving element greatly changes depending on whether the object is at the measurement position or not. On the other hand,
Actually, the range in which the light emission amount of the light emitting device can be varied is not large. For example, the fluctuation range of the light emission amount of a light emitting diode is very small, and if the voltage is reduced to further reduce the light amount, the light emission disappears at once. Therefore, depending on the light emitting device, it is not possible to cope with only the correction by turning on the first switch without the presence of the object to be identified.

According to the third aspect of the present invention, the second switch is turned on / off depending on the presence or absence of the object to be identified, and the correspondence between the physical characteristics of the light receiver and the amount of electricity output to the first contact. Since the relationship is changed, the change stably brings the amount of electricity at the second contact to a fixed value at the time of the correction in response to a large change in the amount of light applied to the light receiving element due to the insertion and removal of the object to be identified. I can do it.

Here, the changing means capable of changing the correspondence between the physical characteristics of the light receiver and the amount of electricity output to the first contact means, for example, if the physical characteristics are resistance and the amount of electricity is voltage, Means for changing the voltage division ratio of the second contact by connecting a resistor in parallel to the light receiver, means for changing the voltage supplied to the circuit to which the light receiver is connected, and the like are possible.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 is a circuit configuration diagram of a light emitting and receiving device 20 provided in an identification device (valuable medium identification device) 100 according to an embodiment of the present invention, and FIG. .

The identification device 100 of this embodiment is similar to that of FIG.
As shown in the figure, bills (value media)
And illuminates the light, and measures the transmitted light to discriminate bills. The light emitting / receiving device 20, the amplifier 30, the A / D converter 3
1. It is composed of a judgment means 32 and the like. Light emitting and receiving device 20
The bill D is conveyed between the light emitting device 5A and the light receiving device 6A, and the received light data is measured.

As shown in FIG. 1, the light emitting and receiving device 20
It includes a correction circuit which is a feature of the present invention, and includes an operational amplifier 1, an analog switch 2 as first switch means, an electric field capacitor 3 as voltage holding means, an amplifier 4, and a light emitting element 5 (for example, a light emitting element 5A). A light emitting diode), a light receiving element 6 (for example, a phototransistor) constituting the light receiver 6A, a variable resistor 7 as changing means for changing the correspondence between the resistance value of the light receiving element 6 and the output voltage, and a switch as second switching means. 8 and resistors 11 and 12
And so on.

The light receiving element 6 is an element that changes the resistance value according to the amount of received light. The contact point between the light receiving element 6 and the resistor 12 forms a contact point P as a first contact point, and outputs an output voltage representing light receiving data. The correspondence between the resistance value of the light receiving element 6 and the output voltage of the contact point P is changed by turning off the switch 8 to enable the connection of the variable resistor 7.

The amplifier 4 and the resistor 11 constitute a current supply circuit for supplying a current to the light emitting element 5. The voltage input from the contact Q is amplified by a predetermined factor by the amplifier 4 and output, and determines the current value supplied to the light emitting element 5.

The electric field capacitor 3 holds the voltage of the contact Q when the switch 2 switches from on to off. The amplifier 4 has a high input impedance and keeps the discharge of the electric field capacitor 3 low.

The operational amplifier 1, for example, inputs the reference voltage 9 to one input terminal, feeds back the output voltage at the node P to the other input terminal, and outputs the voltage after the operational amplification to the node Q
Output to The switch 2 turns on / off the feedback of the output voltage at the contact point P via the operational amplifier 1.

The discriminating apparatus 100 of this embodiment is configured as described above, and transmits a valuable medium while performing correction processing corresponding to the characteristic change of the light emitting element 5 and the light receiving element 6 as follows. Light reception data, which is light, is obtained.

That is, the light emitted from the light emitting element 5 is transmitted through the bill D transported through the identification device 100 and received by the light receiving element 6. The light received by the light receiving element 6 is amplified by the operational amplifier 1 and the contact Q
Is supplied to the light-emitting element 5 via the amplifier 4 and emits light.

First, before the measurement of the light reception data of the valuable medium, the analog switch 1 is turned on to perform the correction.
When the analog switch 1 is turned on, the circuit of the light emitting and receiving device 20 forms a closed loop with the light receiving element 6 and the light emitting element 5, and in any case, the light emitting element 6
The contact P on the collector side of the light emitting element 5 and the light receiving element 6
Irrespective of the positional relationship (even if the distance is long or short), the potential accurately depends on the reference voltage 9. That is, the relationship between the light emitting element 5 and the light receiving element 6 is independent of temperature drift and aging.

That is, in an actual operation, the analog switch 2 is turned on during standby (state in which there is no bill), so that the drift due to the temperature change is always corrected.

In this corrected state, the analog switch 2 is turned off to start measuring the received light data. When the analog switch 2 is turned off, the potential on the cathode side of the light emitting element 5 is held by the action of the electrolytic capacitor 3,
The state of the potential before the analog switch 2 is turned off is maintained.

That is, when a bill is inserted, the analog switch 2 is turned off, so that a temperature drift and a secular change are absorbed. Then, light reception data is measured in this state.

When the discriminating apparatus 100 is a bill discriminating apparatus, the amount of received light is large depending on whether or not a bill is inserted between the light emitting device 5A and the light receiving device 6A. Closed loop state (analog switch 2
Is turned on), the bill validator is operated, and the light receiving element 6 is used in a state where the collector potential of the light receiving element 6 becomes the reference potential.

The brightness of the light emitting element 5 is 100 when the bill is inserted as the object to be identified and when it is not inserted.
There is a difference of about twice. The dynamic range is widened and the difference cannot be absorbed. That is, the luminance of the light emitting element 5 cannot be reduced to 1/100.

Therefore, the collector resistance of the light receiving element 5 is adjusted by turning on / off the analog switch 8 so that the brightness of the light emitting element 5 when the bill is not inserted and when the bill is inserted is the same. That is, when the bill is not inserted, the analog switch is turned on to reduce the resistance on the collector side, and when the bill is inserted, the analog switch is turned off to increase the resistance on the collector side. By this operation, the potential of the contact point P can be brought to the reference potential in a stable state in both the case where the bill is inserted and the case where the bill is not inserted.

The voltage output from the light emitting and receiving device 20 is
Thereafter, the amplifier 30, the A / D converter 31, and the judging means 32
And received as light reception data, and is compared with regular light reception data for discrimination.

As described above, according to the identification apparatus 100 of this embodiment, even if the characteristics of the optical detecting means (the light emitting element 5 and the light receiving element 6) have a temperature drift, a secular change, etc., these are corrected. As a result, high-precision output data based on optical means can be obtained. Therefore, it is possible to reduce the allowable value of the standard pattern used for the bill discrimination and the like, and to improve the performance of the identification device.

The present invention is not limited to the identification device 100 of this embodiment. For example, the collector P of the light receiving element 6 is used as the first contact, but a resistor is connected in series with the emitter. Connect the contact on the emitter side to the first
The contact may be used, or any contact of any circuit configuration may be used as long as the resistance change of the light receiving element 6 can be output as a voltage change. Further, the voltage at the first contact does not need to be output (to the subsequent amplifier 30 or the like). Also, the first
There may be various circuit configurations for correcting the voltage at the first contact to a predetermined value by feeding back the voltage at the contact. In addition, the detailed configuration specifically shown, such as an electric field capacitor as a holding unit and a variable resistor 7 as a changing unit, can be appropriately changed without departing from the gist of the invention.

[0040]

As described above, according to the identification device of the present invention, the output voltage of the first contact on the light receiving device side is fed back to the light emitting device side via the operational amplifier, so that the light emitting device and the light receiving device can be used. Characteristic changes due to temperature drift and aging can be corrected. Then, by switching the first switch,
With the above-mentioned corrected state, measurement of the received light data can be performed as in the related art.

Further, by switching the second switch, it is possible to cope with a large change in the amount of received light when the object to be identified is at the measurement location and when it is not.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a light emitting and receiving device provided in an identification device according to an embodiment of the present invention.

FIG. 2 is a schematic diagram showing the entirety of the identification device.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 operational amplifier 2 analog switch (first switch means) 3 electric field capacitor (voltage holding means) 4 amplifier 5 light emitting element 6 light receiving element 7 variable resistance (change means) 8 analog switch (second switch means) 9 reference voltage 20 light emitting and receiving Apparatus 32 Judgment means D Banknote (value media, object to be identified)

Claims (3)

[Claims] A light-emitting device that changes a light emission amount according to a current amount; and a light-receiving device that changes predetermined physical characteristics according to a light-receiving amount. An identification device that measures received light data of reflected light or transmitted light of an identification object and identifies the identification target based on the received light data, wherein a change in physical characteristics of the light receiver is determined by a change in a predetermined amount of electricity. A first contact that outputs the first contact, and a correction unit that feeds back the amount of electricity of the first contact to adjust the amount of current flowing through the light emitting device to thereby correct the amount of electricity output to the first contact to a predetermined value. A first switch means for returning the electric quantity of the first contact to the correction means before the measurement of the light reception data; and a first switch means for cutting off the feedback at the time of measurement of the light reception data; The amount of current flowing through the light emitter Identification device characterized by comprising a holding means for holding constant. 2. A light emitting device for changing a light emitting amount according to a current amount, and a light receiving device for changing a resistance value as the predetermined physical characteristic according to a light receiving amount, wherein the light emitting device emits light and receives light from the light receiving device. An identification device that measures received light data of reflected light or transmitted light of the identified object and identifies the identified object based on the received light data, wherein a change in resistance of the light receiver is determined by the predetermined electric quantity. A first contact that outputs as a voltage change, a current supply circuit that has an input terminal, supplies current to the light emitting device, and changes a current value to be supplied according to the voltage of the input terminal; and a predetermined reference voltage. An operational amplifier that amplifies and outputs the output voltage of the first contact and the output voltage of the first contact; and outputs the output of the operational amplifier to the input terminal of the current supply circuit before measuring the received light data, A first switch means for cutting off the place, first
2. The identification device according to claim 1, further comprising: voltage holding means for holding a voltage at an input terminal of the current supply circuit constant before and after the switch means interrupts the feedback. 3. A changing means capable of changing a correspondence relationship between a value of a physical characteristic of the light receiver and a value of an electric quantity output to the first contact point, and an object to be identified is located at a measurement position of the light reception data. The identification device according to claim 1, further comprising: a second switch unit that switches the correspondence by operating the change unit when there is no case.