JPH0412518B2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field of the Present Invention> The present invention provides a coin thickness detection method for electrically detecting the thickness of coins inserted in public telephones, vending machines, etc. Regarding equipment.

<Prior art> In public telephones, vending machines, currency exchange machines, etc., it is necessary to detect the thickness of coins to determine the type and authenticity of coins inserted.

For this reason, conventionally, the thickness has been detected by mechanical means or by electrical means.
Install a detection coil in the coin orbit as in No. 42891,
The thickness of the coin was determined by detecting changes in the oscillation frequency of the detection coil as the coin passed.

<Problems to be Solved by the Invention> However, in order to continuously detect the coin thickness at high speed, it is desirable to detect the coin while it is rolling and falling on the coin raceway surface without stopping the coin. With mechanical means, it is difficult to accurately detect minute differences in the thickness of rolling and falling coins, and it is also difficult to accurately detect the thickness of coins that are continuously thrown in at high speed. It was hot.

In addition, as in the above-mentioned Japanese Patent Laid-Open No. 53-42891, since the determination is based on extremely small changes in the detection coil oscillation frequency due to the coin thickness, it is susceptible to noise and it is difficult to accurately determine the thickness. It was.

SUMMARY OF THE INVENTION An object of the present invention is to solve these problems and provide a coin thickness determining device that can accurately determine the thickness of coins even when a large number of coins are continuously inserted.

<Means for Solving the Problems> In order to solve the problems described above, a coin thickness detection device according to a first aspect of the invention includes: an oscillator; a coil that is installed at a predetermined distance in the thickness direction of the coin and causes an inductance change due to the coin falling along the coin orbital surface;
It consists of a capacitor connected in parallel with the coil, and when there is no coin in the excitation magnetic field of the coil in the coin track, the output voltage becomes maximum in tune with the frequency of the output signal of the oscillator, and the output voltage reaches the maximum in the coin track. A tuned circuit that loses synchronization and reduces its output voltage when a coin passes through the coil installation position; and a coin detection circuit that outputs a coin detection signal while the amount of change in the output voltage of the tuned circuit is equal to or higher than a predetermined level. a reset circuit that detects the starting edge of the coin detection signal and outputs a reset signal; a peak voltage that holds the peak voltage when the change in output voltage of the tuning circuit reaches a maximum after the reset signal; a peak value holding circuit that resets the held peak value voltage by the outputted reset signal; a charging circuit that is reset and starts charging every time the coin detection signal ends; The peak value voltage held in the value holding circuit and the charging voltage of the charging circuit are compared to generate a pulse signal that starts at the end of the coin detection signal and ends when the charging voltage matches the peak value voltage. A pulse signal output circuit that outputs a pulse signal, and a determination circuit that receives a pulse signal from the pulse signal output circuit, compares and calculates the width of the pulse signal with a pre-stored pulse width, and determines the thickness of the coin. There is.

Further, the coin thickness detection device according to the second invention includes an oscillator, which is excited by the output signal of the oscillator, and is installed at a predetermined distance in the thickness direction of the coin, facing the coin orbital surface, and A coil that causes inductance changes due to coins falling along the track surface,
It consists of a capacitor connected in parallel with the coil, and when there is no coin in the excitation magnetic field of the coil in the coin track, the output voltage becomes maximum in tune with the frequency of the output signal of the oscillator, and the output voltage reaches the maximum in the coin track. A tuned circuit that loses synchronization and reduces its output voltage when a coin passes through the coil installation position; and a coin detection circuit that outputs a coin detection signal while the amount of change in the output voltage of the tuned circuit is equal to or higher than a predetermined level. a reset circuit that detects the starting edge of the coin detection signal and outputs a reset signal; a peak voltage that holds the peak voltage when the change in output voltage of the tuning circuit reaches a maximum after the reset signal; a peak value holding circuit that resets the peak value voltage held by the outputted reset signal; a charging circuit that starts charging every time the coin detection signal terminates; and the peak value holding circuit. A pulse that outputs a pulse signal that starts at the beginning of the coin detection signal and ends when the charging voltage reaches the peak voltage by comparing the peak value voltage held at the peak voltage and the charging voltage of the charging circuit. a signal output circuit, which receives a pulse signal from the pulse signal output circuit and the coin detection signal, and compares and calculates the width of the pulse signal after the end of the coin detection signal with a pre-stored pulse width; A determination circuit for determining the thickness of the coin is provided.

<Function> With this arrangement, while the coin passes, the tuning circuit loses its tuning and the output voltage decreases. During this period of decline in which the value has changed beyond a certain level, a coin detection signal is output from the coin detection circuit. At the beginning of this coin detection signal, a reset signal is output from the reset circuit. The peak value holding circuit is reset by this reset signal, and the peak value voltage of the output change of the tuning circuit when the coin passes is held. Charging of the charging circuit is started at each termination of the coin detection signal. The pulse signal output circuit compares the peak value voltage with this charging voltage.

In the first invention, a pulse signal having a time width that starts from the end of the coin detection signal and ends when the charging voltage reaches this peak value voltage is output. The determination circuit compares and calculates the pulse width of this pulse signal with a previously stored pulse width to detect the thickness.

In the second invention, a pulse signal having a time width that starts at the beginning of the coin detection signal and ends when the charging voltage reaches this peak value voltage is output. The determination circuit receives this pulse signal and the coin detection signal, and
The width of this pulse signal after the end of the coin detection signal is compared with a previously stored pulse width to perform thickness detection.

In this way, each time an inserted coin passes the coil installation position, a coin detection signal is output, and each time this coin detection signal ends, charging to the charging circuit for thickness detection starts, and this charging voltage Since the thickness is detected by comparing the peak value of the output change of the tuning circuit when the coins pass, even if the intervals between successively inserted coins are close to each other, the thickness of each coin can be accurately detected one after another. is detected.

<Embodiment of the present invention> An embodiment of the present invention shown in the drawings will be described below.

FIG. 1 shows the circuit configuration of a coin thickness detection device according to a first embodiment of the invention.

In the figure, reference numeral 1 denotes an oscillator that outputs a rectangular wave oscillation signal of a predetermined frequency, and the coil 22 of the tuned circuit 2 is excited by the output of the oscillator 1.

The tuned circuit 2 is composed of a capacitor 21 and a coil 22 connected in parallel, and the coil 22 is
As shown in FIG. 2, the coin A is placed in parallel with a predetermined distance apart from a coin raceway surface B on which the coin A rolls and falls while keeping its abdomen A in contact with the coin raceway surface B.

Then, when the coin A does not exist on the coin orbital surface B (that is, when the coin A does not exist within the excitation magnetic field generated by the coil 22), the tuning circuit 2
The capacitor 21 is adjusted so that its output voltage is maximized in tune with the oscillator frequency of
When a coin passes through the coin orbital surface B, the excitation magnetic field by the coil 22 changes and the inductance of the coil 22 changes, which causes the tuning circuit 2 to be out of tune and the output voltage to drop.

This inductance change is larger as the distance from the surface of coin A to coil 22 is shorter (that is, the thicker the coin A is), so the output voltage becomes lower as the thickness of the coin becomes larger.

Further, as the coin A approaches the center of the coil 22, the amount of change in inductance increases, so when the coin A passes through the coil 22, the output voltage becomes the lowest.

3 is a rectifying and smoothing circuit for rectifying and smoothing the output voltage of the tuning circuit 2, which includes a diode 31 and a resistor 3.
2, 33, a capacitor 34, etc.

The time constant of this capacitor and resistor is set to a value that can sufficiently smooth the tuning frequency component of the tuning circuit 2 and can sufficiently follow the rolling and falling speed of the coin A.

Reference numeral 4 denotes a DC amplifier circuit for adjusting the gain of the output of the rectifying and smoothing circuit, and is composed of a coupling capacitor 41, resistors 42 to 44, a differential amplifier 45, and the like.

5 is a coin detection circuit that compares the fluctuation in the output voltage of the tuning circuit 2 whose gain has been adjusted by the amplifier circuit 4 with a certain set level and outputs a coin detection signal when the fluctuation is below this set level, Resistance 51~5
4. It is composed of differential amplifiers 55, 56, etc.

The fluctuation in the output voltage of the tuned circuit 2 is such that as the coin A approaches the coil 22, the output voltage begins to decrease, becomes the lowest at the center of the coil 22, and recovers as it moves away from the coil 22. The falling edge approximately corresponds to when the leading edge A ₁ of the coin A approaches the coil 22, and the falling edge approximately corresponds to when the trailing edge A ₂ leaves the coil 22.

6 is a peak value detection unit that holds the lowest value (peak value) of the output voltage of the amplifier circuit 4, and includes differential amplifiers 61, 62, a diode 63, a resistor 64, a capacitor 65, and a peak value holding circuit. , a capacitor 66 and a resistor 6 forming a reset circuit that resets the peak value of the previously passed coin at the rising edge of the coin detection signal of the coin detection circuit 5.
7, an analog switch 68, and a resistor 69.

The capacitor 66 and the resistor 67 constitute a differentiator, which receives the coin detection signal, and at the rising edge of the coin detection signal, gives a short positive pulse to the analog switch 68, thereby turning the analog switch 68 on instantaneously. By momentarily turning on the analog switch 68, the peak value held in the capacitor 65 is reset, making it possible to hold the peak value for the coin A currently passing.

7 is a pulse width conversion unit for converting the output voltage representing the peak value of the peak value holding circuit 6 into a pulse width, and includes a differential amplifier 71, a resistor 72, and a charging circuit forming a pulse signal output circuit. Forming capacitor 73, resistor 74, inverter 75, capacitor 76, resistor 77, analog switch 7
8 and a resistor 79.

The capacitor 76 and the resistor 77 constitute a differentiator, which receives a coin detection signal from the coin detection circuit 5 via an inverter 75, and outputs one short positive pulse to the analog switch 7 when the coin detection signal falls.
8 to instantly turn on the analog switch 78. In this way, by instantaneously turning on the analog switch 78, the charge stored in the capacitor 73 is instantaneously discharged, and from this point on, the pulse width conversion operation, that is, the charging operation of the capacitor 78 is started.

8 receives the pulse signal from the pulse signal output circuit 7, compares its width with a pre-stored pulse width, and determines the thickness of the coin A. This is a determination circuit that outputs control signals to each part.

9 provides a bias voltage to the amplifier circuit 4 and a reference voltage to the coin detection circuit 5, and also provides a voltage change due to a temperature change caused by a temperature compensation diode 91 as a bias voltage of the amplifier circuit 4. Accordingly, the temperature compensation circuit outputs a bias voltage that offsets temperature changes in the output voltage corresponding to the coin thickness of the amplifier circuit 4,
Diode 91 for temperature compensation, resistors 92, 93,
It is composed of a differential amplifier 94.

Next, the operation of the coin thickness detecting device constructed as described above will be explained with reference to a timing chart of each part shown in FIG.

When the coin A does not exist within the magnetic field generated by the coil 22 on the coin orbital surface B, the output voltage of the tuning circuit 2 is tuned to the frequency of the oscillation signal of the oscillator 1 and is in the maximum output state.

When the inserted coin A rolls down the coin raceway surface B and reaches the excitation magnetic field of the coil 22, the inductance of the coil 22 changes and the tuned circuit 2
is out of synchronization, and while the coin a passes through (), (), () as shown in Fig. 2, the tuning circuit 2
The output voltage of coin A gradually decreases and reaches its lowest value (coin A
reaches the center of the coil 22 (in the state of )), it gradually recovers.

When the coin A leaves the magnetic field, the tuned circuit 2 is retuned and its output voltage is again at its maximum. As described above, the greater the thickness of the coin A, the greater the amount of voltage drop.

FIG. 3a shows the output signal waveform of the tuning circuit 2.

The output signal of the tuning circuit 2 is rectified and smoothed by the rectifying and smoothing circuit 3, and the gain is adjusted by the DC amplifier circuit 4, resulting in the signal shown in FIG. 3b.

The output of the amplifier circuit 4 is sent to a coin detection circuit 5 and a peak value detection circuit 6.

In the coin detection circuit 5, the resistance 9 of the temperature compensation circuit 9
2, 93, the reference voltage level determined by the diode 91 is given from the differential amplifier 94 constituting the voltage follower, this level is compared with the output level of the amplifier circuit 4, and is inverted by the final stage differential amplifier 56. Then, as shown in FIG. 3c, a coin detection signal is output, which rises when the output level of the amplifier circuit 4 becomes lower than the reference level, and falls when it recovers and becomes higher.

The rise of this coin detection signal approximately corresponds to the time when the leading edge A ₁ of the coin A approaches the coil 22 in FIG. 2, and the fall corresponds to the time when the trailing edge A ₂ leaves the coil 22. There is.

Note that when the output voltage of the DC amplifier circuit 4 corresponding to the coin pressure fluctuates due to temperature change, the output voltage of the temperature compensation circuit 9 is biased to the DC amplifier circuit 4 so as to offset this fluctuation. It is possible to obtain an output voltage corresponding to the coin thickness that is stable against temperature changes.

The output of the coin detection circuit 5 is sent to the reset circuit of the peak value detection section 6 and the charging circuit of the pulse width conversion section 7.

A differentiator consisting of a capacitor 66 and a resistor 67 in the reset circuit generates a short positive pulse (shown at d in FIG. 3) at the rising edge of the coin detection signal of the coin detection circuit 5, thereby triggering the analog switch. 68
turns on instantly.

During this on period, the charge on capacitor 65 representing the peak value for the previously passed coin is transferred to resistor 65.
9, making it possible to maintain the peak value for coin A during its current passage.

Due to the discharge of the capacitor 65, the potential at point P of the peak value holding circuit becomes the same potential as the power supply V, and the input to the inverting terminal of the differential amplifier 61 constituting the voltage follower becomes approximately V.

Therefore, the differential amplifier 61 of the peak value holding circuit 6
When the output of the amplifier circuit 4 applied to the non-inverting terminal of the coin A decreases as the coin A moves, the output terminal of the differential amplifier 61 becomes negative. Therefore, diode 63 becomes conductive.

Since the capacitor 65 is charged to the opposite polarity to the power supply V with an extremely small time constant provided by the diode 63 and the resistor 64, the potential at the point P decreases following the decrease in the output voltage of the amplifier circuit 4.

The output voltage of amplifier circuit 4 is the lowest value (peak value)
Then, when the recovery starts, the output terminal of the differential amplifier 61 becomes positive and the diode 63 is cut off, so the potential at point P (the differential amplifier 62
(potential at the output terminal) is held at its peak value.

3e shows the output signal of the differential amplifier 62. FIG.

The output of the differential amplifier 62 is input to the non-inverting terminal of the differential amplifier 71 of the pulse signal output circuit 7.

The pulse signal from the coin detection circuit 5 is also input to the inverter 75 of the pulse width converter 7, but at the falling edge of this pulse signal, the differentiator consisting of the capacitor 76 and the resistor 77 generates a short positive pulse. (shown at f in FIG. 3) is output.

As a result, the analog switch 78 is turned on instantaneously, and during this ON period, the charge in the capacitor 73 is instantaneously discharged.

Since the analog switch 78 is immediately turned off, charging of the power supply V to the capacitor 73 via the large resistance value resistor 74 starts from this point.

g in FIG. 3 indicates the input signal of the inverting terminal of the differential amplifier 71 (ie, the potential of the capacitor 73).

The differential amplifier 71 starts up when the charge on the capacitor 73 is discharged, and when the charging progresses and the potential on the capacitor 73 reaches the level of the heak value input to the non-inverting terminal (dotted line in Figure 3 g), the differential amplifier 71 starts up. , outputs a pulse width signal (shown at h in FIG. 3) with a falling width M1.

Since the terminal voltage of the capacitor 73 changes over time due to the time constant of the resistor 74 and the capacitor 73, the peak value output from the differential amplifier 62 of the peak value holding circuit is converted into a pulse width proportional to the peak value. Therefore, this pulse width changes depending on the thickness of the coin A.

The width of this pulse signal is compared with the pulse width stored in advance in the determination circuit 8, and the width of the coin A is calculated.
The thickness of the sensor is determined, and a control signal based on this is output to the relay, display, and other parts.

FIG. 4 is a circuit diagram showing an embodiment of the second invention, and in this embodiment, the inverter 75, capacitor 76, and resistor 77 of the pulse width converter 7 in the embodiment shown in FIG. 1 are omitted. It is. Due to this omission, the output signal of the coin detection circuit 5 is directly applied to the analog switch 78 (as shown at f' in FIG. 5).

Therefore, the analog switch 78 is turned on when the coin detection circuit output rises, and the charge in the capacitor 73 is discharged, and is turned off when the coin detection circuit output falls, and charging of the capacitor 73 starts. Therefore, the input signal at the inverting terminal of the differential amplifier 71 is
It will look like g' in Figure 5.

Therefore, the output of the differential amplifier 71 has a width from the rise of the coin detection circuit output (when the capacitor 73 is discharged) to the start of charging of the capacitor 73.
M2 and the width M1 from when the capacitor 73 starts discharging until the discharge voltage reaches the peak value level (dotted line in Figure 5g) (M2 + M1)
The result is a pulse signal with a width of , as shown in h' in FIG.

In this case, the coin detection signal of the coin detection circuit 5 and the pulse signal of the differential amplifier 71 of the pulse signal output circuit are sent to the determination circuit 8.

The determination circuit 8 determines the thickness of the coin A by comparing the width of the pulse signal (ie, the element of M1) after the fall of the coin detection signal with a pre-stored pulse width.

In the above embodiment, the larger the thickness of the coin, the smaller the pulse width of the output from the pulse signal output circuit 7. However, as shown in e' in FIG. If the output signal has an inverted waveform, the pulse width can be increased to the extent that the thickness of the coin is large.

Further, in the above embodiment, the output of the differential amplifier 71 of the pulse signal output circuit is connected to a microcomputer, the pulse value is measured by a counter in the microcomputer, and the determination is made by comparing it with a pre-stored pulse width. It is also possible to have the circuit 8 operate inside the microcomputer, and in this case, a timing generation oscillator inside the microcomputer can be used as the oscillator 1.

Although specific examples of the present invention have been described above, various modifications can be made in the configuration of each part.

<Effects of the present invention> As explained above, in the coin thickness detection device of the present invention, a coil is installed facing the coin raceway surface at a predetermined distance in the coin thickness direction, and a tuning circuit including the coil is installed. is synchronized to reach the maximum output when there is no coin within the excitation magnetic field of the coil in the coin orbit, and the drop in output voltage due to out-of-synchronization caused by changes in coil inductance while the coin is passing is avoided. While it exceeds a certain level,
A coin detection signal is output, and at the beginning of this coin detection signal, peak value holding is reset to hold a new peak value. Then, at the end of this coin detection signal, the charging circuit starts a new charging operation, outputs a pulse signal with a pulse width corresponding to the peak value voltage, and detects a coin depending on the width of this pulse signal and the pre-stored width. I am trying to detect the thickness.

Since the thickness is detected based on the peak value of the output change of the tuning circuit, the thickness of the coin can be accurately detected while it is rolling and falling without having to stop the coin by electrical means.

In addition, the level of the output voltage change of the tuning circuit 2 caused by the passing of a coin is detected and output as a coin detection signal of the coin detection circuit, and the start and end times of this coin detection signal are detected by peak value detection operation and charging start. Since it is used as a timing signal for pulse width conversion operation, even when a large number of coins are continuously inserted at high speed, each coin is reliably input one after the other without error.
The thickness of the sheet can be detected.

Furthermore, since the detection is performed not by the change in the oscillation frequency of the detection coil but by the peak value of the change in the output of the tuning circuit, the influence of noise is also reduced and accurate detection is possible.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the first invention, FIG. 2 is an explanatory diagram showing the relationship between coin passage and the coil,
Fig. 3 is a timing chart showing the operation of each part in Fig. 1, Fig. 4 is a circuit diagram showing the embodiment of the second invention, and Fig. 5 is a timing chart showing the operation of each part in the embodiment shown in Fig. 4. FIG. 6 is a timing chart of yet another embodiment. DESCRIPTION OF SYMBOLS 1... Oscillator, 2... Tuning circuit, 3... Rectification smoothing circuit, 4... DC amplifier circuit, 5... Coin detection circuit, 55, 56... Differential amplifier, 6... Peak value detection section, 61 , 62... Differential amplifier, 68... Analog switch, 7... Pulse width converter, 71...
... Differential amplifier, 78 ... Analog switch, 8 ...
...Judgment circuit, 9...Temperature compensation circuit.

Claims (1)

[Claims] 1. An oscillator, which is excited by the output signal of the oscillator, is installed at a predetermined distance in the thickness direction of the coin, facing the coin orbital surface, and is configured to fall along the coin orbital surface. a coil that causes an inductance change depending on a coin;
It consists of a capacitor connected in parallel with the coil, and when there is no coin in the excitation magnetic field of the coil in the coin track, the output voltage becomes maximum in tune with the frequency of the output signal of the oscillator, and the output voltage reaches the maximum in the coin track. A tuned circuit that loses synchronization and reduces its output voltage when a coin passes through the coil installation position; and a coin detection circuit that outputs a coin detection signal while the amount of change in the output voltage of the tuned circuit is equal to or higher than a predetermined level. a reset circuit that detects the starting edge of the coin detection signal and outputs a reset signal; a peak voltage that holds the peak voltage when the change in output voltage of the tuning circuit reaches a maximum after the reset signal; a peak value holding circuit that resets the peak value voltage held by the outputted reset signal; a charging circuit that is reset every time the coin detection signal terminates and starts charging; A pulse signal that starts at the end of the coin detection signal and ends when the charging voltage reaches the peak value voltage by comparing the peak value voltage held in the peak value holding circuit and the charging voltage of the charging circuit. and a determination circuit that receives the pulse signal from the pulse signal output circuit and compares and calculates the width of the pulse signal with a pre-stored pulse width to determine the thickness of the coin. Coin thickness detection device. 2. an oscillator, which is excited by the output signal of the oscillator, is installed at a predetermined distance in the thickness direction of the coin, facing the coin orbital surface, and creates an inductance by a coin falling along the coin orbital surface; A coil that causes change,
It consists of a capacitor connected in parallel with the coil, and when there is no coin in the excitation magnetic field of the coil in the coin track, the output voltage becomes maximum in tune with the frequency of the output signal of the oscillator, and the output voltage reaches the maximum in the coin track. A tuned circuit that loses synchronization and reduces its output voltage when a coin passes through the coil installation position; and a coin detection circuit that outputs a coin detection signal while the amount of change in the output voltage of the tuned circuit is equal to or higher than a predetermined level. a reset circuit that detects the starting edge of the coin detection signal and outputs a reset signal; a peak voltage that holds the peak voltage when the change in output voltage of the tuning circuit reaches a maximum after the reset signal; a peak value holding circuit that resets the peak value voltage held by the outputted reset signal; a charging circuit that starts charging every time the coin detection signal terminates; and the peak value holding circuit. A pulse that outputs a pulse signal that starts at the beginning of the coin detection signal and ends when the charging voltage reaches the peak voltage by comparing the peak value voltage held at the peak voltage and the charging voltage of the charging circuit. a signal output circuit, which receives a pulse signal from the pulse signal output circuit and the coin detection signal, and compares and calculates the width of the pulse signal after the end of the coin detection signal with a pre-stored pulse width; A coin thickness detection device comprising a determination circuit for determining coin thickness.