JPH10334299A - Coin selection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the selection accuracy of coins with a simple circuit configuration by using a synthesis output being a synthesis of reference signals with pluralities of frequencies so as to evaluate each coil based on a coordinate denoted by coin specific data obtained for each frequency component. SOLUTION: Sine wave oscillators 221, 222 generate sine wave with frequencies f1 , f2 which differ from each other. The sine wave signals with the frequencies f1 , f2 are synthesized into a signal g(t) with a composite frequency, and the signal g(t) is fed to a bridge circuit 28 consisting of resistors 24, 25, a sensing coil 26 to which a coin of a selection object approaches, and a temperature compensation coil 27. A detection signal s(t) outputted when a coin passes the sensing coil 26 is amplified by an amplifier 31 and fed to a DSP 30, where fast Fourier transform is conducted as frequency analysis processing and a phase and an amplitude for each of the frequencies f1 , f2 are calculated. A CPU 33 processes them to express the phase and the amplitude as data specific to the coin as a coordinate on a plane. Thus, the accuracy is improved more than that by discrimination by a single frequency.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coin sorting apparatus for promoting the automation of toll collection on, for example, toll roads.

[0002]

2. Description of the Related Art As is well known, coin sorters are used in a wide variety of fields such as unmanned automatic toll booths and vending machines. By the way, most of the coin sorting methods used in these coin sorting devices utilize an impedance change caused by a magnetic field of a coil approaching a coin.

FIG. 6 shows a circuit configuration of the coin sorting apparatus. In FIG. 6, reference numeral 11 denotes a sine wave oscillator which generates a sine wave signal. This sine wave signal
A bridge circuit including a detection coil 12 and a temperature compensation coil 13 to which coins to be sorted are brought close, and resistors 14 and 15 forming a balance circuit for balancing the detection coil 12 and the temperature compensation coil 13. 16. The bridge circuit 16 generates a magnetic field from the detection coil 12 and the temperature compensation coil 13 based on a sine wave signal output from the sine wave oscillator 11.

The sine wave signal output from the sine wave oscillator 11 is supplied to a voltage comparator 17. This voltage comparator 17 is, as shown in FIG.
At time S when the sine wave from 1 passes through 0 volt,
An interrupt signal INT-A shown in FIG.
It is supplied to a CPU (Central Processing Unit) 18.

The detection signal output from the bridge circuit 16 is amplified by an amplifier 19 and supplied to a voltage comparator 20 and an AD converter 21. This detection signal indicates that the voltage comparator 20 whose amplitude and phase change when a coin approaches the detection coil 12, as shown in FIG.
At time T when the detection signal from the bridge circuit 16 passes 0 volt, the interrupt signal INT shown in FIG.
-B is generated and supplied to the CPU 18. AD converter 2
1 converts the detection signal from the amplifier 19 into a digital signal and outputs the digital signal to the CPU 18.

Therefore, the CPU 18 monitors the phase delay from the time S of the sine wave signal to the time T of the detection signal,
To sort out this phase delay as coin-specific data,
refer. This phase delay is a factor mainly determined by the material of the coin.

[0007] When the voltage comparator 20 generates an interrupt, the CPU 18 returns to the peak at time U at which time corresponding to 1/4 period has elapsed from time T, as shown in FIG. The value is obtained from the output value of the AD converter 21 and used as an amplitude value for internal processing of coin sorting.
This amplitude value mainly depends on the size of the coin.

By the way, in the above-mentioned coin sorting apparatus, even if there is a slight difference in size due to the material composition and the laminated structure of the coin, there is a case where there is only a slight difference in coin-specific data when a single frequency is used. is there. In such a case, it is difficult to make a correct discrimination in operation in consideration of the influence of external noise, temperature, and the effects of deformation and variation of coins.

Therefore, conventionally, it has been considered to evaluate data based on different relative relationships between data derived from the material of the coin and data derived from the size using a plurality of different frequencies. In this case, it is necessary to provide coils, detection / signal processing circuits, and the like by the number of frequencies to be used, so that the device becomes large-scale and complicated.

[0010]

As described above, in the conventional coin sorting apparatus, coins are sorted only at a single frequency. Therefore, when various effects given to coins are taken into consideration, certain types of coins can be used. Discrimination becomes difficult. Further, when the determination is performed using a plurality of different frequencies, it is necessary to provide coils, detection / signal processing circuits, and the like by the number of frequencies to be used, which leads to an increase in the size and complexity of the device. Therefore,
SUMMARY OF THE INVENTION An object of the present invention is to provide a coin sorting device that can improve coin sorting accuracy with a simple circuit configuration.

[0011]

According to the present invention, there is provided a coin sorting apparatus comprising: a detection coil to which coins to be sorted are brought close to each other; a reference coil having a paired relationship with the detection coil; Generating a bridge circuit composed of a balance circuit for balancing the reference coil and a plurality of reference signals having different frequencies,
Frequency supply means for synthesizing the plurality of frequency reference signals and exciting the detection coil and the reference coil of the bridge circuit with respect to the synthesized output, and a coin to be sorted is detected based on the output of the frequency supply means. The output of the bridge circuit when approaching the coil is subjected to frequency analysis processing to detect the amplitude and phase difference of each frequency component, and based on the detection result, determine the type of coin approaching the detection coil. And a coin discrimination processing means for performing

According to this configuration, by evaluating each coin at the coordinates indicated by the coin-specific data obtained for each frequency component, the accuracy of coin discrimination can be improved as compared with discrimination based on a single frequency. . In addition, since the output of the bridge circuit including different frequencies is subjected to frequency analysis processing by the coin discrimination processing means to generate data for each frequency component, detection coils corresponding to a plurality of frequencies, detection / signal processing circuits, and the like are separately provided. It is not necessary to provide.

[0013]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows a circuit configuration of an embodiment of the present invention. In FIG. 1, reference numerals 221 and 222 denote sine wave oscillators for f1 and f2, which generate sine wave signals having different frequencies f1 and f2, respectively. The sine wave signals of these frequencies f1 and f2 are signals as shown in FIGS. 2A and 2B, and the composite frequency (f) shown in FIG.
1 + f2) is synthesized with the signal g (t).

The frequency used here is effective for discriminating the coin to be discriminated, and is selected so that each synthesized waveform can be applied for at least one cycle while the coin passes through the detection coil 26. It shall be.

The composite frequency signal g (t) is applied to a bridge circuit 28 composed of resistors 24 and 25, which are balanced circuits, a detection coil 26 to which coins to be sorted are brought close, and a temperature compensation coil 27.

The bridge circuit 28 includes the detection coil 2
6 and the coil 27 for temperature compensation are excited by the signal g (t) as shown in FIG. 3 (a), and an eddy current loss occurs when the coin passes through the detection coil 26, as shown in FIG. 3 (b). The detection signal S (t) is output. The detection signal S (t) is amplified by the amplifier 31, and then is converted to a DSP (Digital Signal Process).
sor) 30.

The DSP 30 performs a fast Fourier transform process (FFT) on the detected signal S (t) as a frequency analysis process.
To generate digital data corresponding to the frequency as shown in FIGS. 3 (c) and 3 (d). Note that the DSP
30 and the CPU 33 detect the detection signal S of the bridge circuit 28.
(T) constitutes a coin discrimination processing means for discriminating the type of coin near the detection coil 26.

FIG. 4 is a flow chart for explaining the operation of the DSP 30. First, when started (Step S11), the DSP 30 executes Step S12.
Then, the detection signal S (t) of the bridge circuit 28 is read, and in step S13, the read detection signal S (t) is read.
Perform the FFT processing on.

Then, the DSP 30 proceeds to step S14.
Thus, the real part data R (f1) and R (f2) and the imaginary part data I (f1) and I (f2) corresponding to the frequencies as shown in FIGS. 3 (c) and (d) are obtained from the DSP 30. Here, the real part data R (f1) and R (f2) are real part data corresponding to the frequencies f1 and f2, and the imaginary part data I (f1) and I (f
2) is imaginary part data corresponding to the frequencies f1 and f2.

Next, the DSP 30 proceeds to step S15.
The real part data R (f
1), R (f2) and imaginary part data I (f1), I (f
Based on 2), the phase and amplitude values for each of the frequencies f1 and f2 are calculated. The phase and amplitude values are obtained by the following equations.

[0021]

(Equation 1)

Thereafter, the DSP 30 executes the above step S15
The phase and amplitude values for each of the frequencies f1 and f2 calculated in
Output to U33. Then, the CPU 33 executes the DSP 30
The phase and amplitude values for each of the frequencies f1 and f2 obtained from
The type of the coin is specified based on a result of the comparison with the phase and amplitude value parameters obtained in advance for various coins.

Here, in the coin-specific data obtained by the processing of the CPU 33, as shown in FIG. 5, the phase and amplitude values are expressed as coordinates on a plane. This phase is dominant in the material and frequency of the coin, but if the material is a composite material or a coin having a laminated structure, the relative relationship tends to be different due to the difference in frequency such as coin A and coin B. Further, the amplitude value is dominant in the size of the coin, but a different relative relationship is obtained depending on the frequency depending on the impurity component contained in the coin and the like. Further, the amplitude value becomes maximum when the coin passes through the detection coil 26.

Therefore, according to the above embodiment, the detection signal from the bridge circuit 28 is subjected to Fourier transform processing by the DSP 30 to obtain data for each of the frequencies f1 and f2. Each frequency f1, f2
By performing the evaluation using the coordinates indicated by the coin-specific data obtained for each coin, it is possible to improve the discrimination accuracy of the coin as compared with the discrimination based on a single frequency.

The CPU 33 receives the phase and amplitude values of the detection signal of the bridge circuit 28 subjected to the Fourier transform processing for each frequency f1 and f2 from the DSP 30, and discriminates the coin based on the phase and amplitude values. Since the processing is performed, it is also possible to reduce the load on the processing and speed up the processing.

Further, the DSP 30 operates at different frequencies f1,
Since the detection signal of the bridge circuit 28 including f2 is subjected to Fourier transform processing to generate data for each of the frequencies f1 and f2, a detection coil corresponding to a plurality of frequencies f1 and f2, a detection / signal processing circuit, and the like are separately provided. You don't have to.

In the above embodiment, the type of coin is determined using two different frequencies f1 and f2. However, the type of coin may be determined using three or more different frequencies. Of course you can.

Further, the present invention is not limited to the above-described embodiment, and it goes without saying that various modifications can be made without departing from the spirit of the present invention.

[0029]

As described in detail above, according to the present invention,
With a simple circuit configuration, it is possible to provide a coin sorting device capable of improving coin sorting accuracy.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing an embodiment of a coin sorting apparatus according to the present invention.

FIG. 2 is a diagram showing an operation of a signal up to a process in which a plurality of frequencies are combined in the embodiment.

FIG. 3 is an exemplary view showing the operation of the signal up to the stage in which a signal in which a plurality of frequencies are combined is subjected to Fourier transform processing in the embodiment;

FIG. 4 is a flowchart shown to explain the operation of the DSP according to the embodiment;

FIG. 5 is a distribution diagram of coin-specific data in the embodiment.

FIG. 6 is a circuit configuration diagram showing a conventional coin sorting device.

FIG. 7 is a view showing the operation of signals in the conventional device.

[Explanation of symbols]

 11, a sine wave oscillator, 12, 26, a detection coil, 13, 27, a temperature compensation coil, 14, 15, 24, 25, a resistor, 16, 28, a bridge circuit, 17, 20, a voltage comparator, 18, 33 ... CPU, 19, 31 ... amplifier, 21 ... AD converter, 221 ... sine wave oscillator for f1, 222 ... sine wave oscillator for f2, 23 ... waveform synthesizer, 30 ... DSP.

Claims (1)

[Claims] 1. A detection coil in which coins to be sorted are brought close to each other, a reference coil having a paired relationship with the detection coil, and a balancing circuit for balancing the detection coil and the reference coil. A reference signal having a plurality of frequencies different from each other, and synthesizing the reference signals having the plurality of frequencies to excite a detection coil and a reference coil of the bridge circuit with respect to the synthesized output. Frequency supply means, based on the output of the frequency supply means, performs a frequency analysis process on the output of the bridge circuit when a coin to be sorted comes close to the detection coil, and performs amplitude and position analysis for each frequency component. And a coin discrimination processing means for detecting a phase difference and determining a type of a coin approaching the detection coil based on the detection result. Coin sorting apparatus characterized by comprising.