JPS6059633B2 - Coin data measurement method - Google Patents

Description

Detailed Description of the Invention (a) Industrial Application Field The present invention relates to a coin data measurement method in a coin identification device, and in particular to a method for detecting magnetic flux induced by eddy currents generated within a coin to be measured in an oscillating magnetic field. The present invention relates to a method of measuring a signal phase difference between an oscillation side and a detection side as coin data.

(b) Conventional technology A method of placing a coin in an oscillating magnetic field and measuring coin data based on the signal phase difference between the oscillating side and the detecting side is disclosed in Japanese Patent Application Laid-open No. 49
There is a technique disclosed in Japanese Patent No. -95694.

The first method is to sandwich a coin to be measured, place an oscillating coil and a detection coil facing each other, and measure the signal phase difference between the two coils.
This will be explained with a diagram. The signal a of the oscillation coil is converted into a rectangular wave a' with a predetermined signal level L, and the signal of the detection coil caused by the passage of a coin is converted from a rectangular wave to ', and the rectangular wave a' and the rectangular wave are inverted. Take the logical product c with the waveform. This signal c
is a phase difference coin generated by a coin, and the value of the phase difference is measured by taking the logical product of one of the coins c and the clock pulse d and counting the clock pulses e generated within the generation period of the coin c. It is something. This counter pulse counting process is carried out by setting a certain phase difference measurement period that always includes one piece of phase difference information c, and operating a counter within that period. ←→ Problem to be solved by the invention However, when the period of the signal a of the oscillation coil increases or decreases due to variations in circuit components or temperature changes, the interval between the waveforms e also increases or decreases, as shown in FIGS. 2 and 3. A problem occurs.

That is, when the interval between waveforms e becomes shorter as shown in FIG.
The phase difference of the next cycle is also detected during the same measurement period f, and in order to capture two types of phase difference information, a larger value than the actual value is detected. If only a part of the phase difference information is captured, a value smaller than the actual value will be detected.From the above points, the present invention provides a coin data measurement method that can reliably detect one phase difference information during the measurement period. There are things.

(Means for Solving the Problems) The present invention provides an oscillating coil that forms an oscillating magnetic field at a predetermined oscillating frequency, and a detection system that detects magnetic flux induced by eddy currents generated in a coin to be measured in the oscillating magnetic field. Equipped with a coil, extracts a phase difference signal in the same period between a reference signal related to the oscillation magnetic field and a detection signal of the detection coil, and counts clock pulses with a frequency sufficiently higher than the oscillation frequency within the period of the phase difference signal using a counter. This is a device that measures coin data by setting a phase difference measurement period that is greater than or equal to the maximum fluctuation period of the oscillation frequency within the allowable error range and less than or equal to I times the minimum fluctuation period, and when the reference signal or detection signal is The phase difference measurement period is started from the time when the signal intersects with a predetermined signal level.

(E) Effect According to the above measurement method, only one phase difference signal is detected within the phase difference signal period even if the oscillation frequency fluctuates within the allowable error range.

(F) Embodiment In the present invention, the tolerance range of the oscillation circuit including the oscillation coil must be set.

The frequency of an oscillation circuit fluctuates due to variations in component parts or temperature changes, but in this example, the allowable error range is set to ±20%, and the circuit is designed so that even if the frequency fluctuates, it stays within this range. It is relatively easy to keep the tolerance range within ±20% like this, and if it fluctuates by more than ±20%, the degree of penetration of the magnetic flux into the coin will differ and it will be difficult to measure the intended coin data. Therefore, this range is reasonable. In the case of detecting the phase difference signal c, the following will be explained with reference to FIG.
T where the signal a of the oscillation coil intersects with the signal level L. point and T
The phase difference measurement period is set between one point (ie, 1.5 cycles), and in the present invention, it is set under the following conditions. That is, for a -20% fluctuation of signal a, the upper limit of the phase difference measurement period is equal to signal a.
Set to 1.5 times or less of the minimum fluctuation period of signal a, +2 of signal a.
The lower limit of the phase difference measurement period for a 0% fluctuation is set to be greater than or equal to the maximum fluctuation period of the signal a. With such a setting, even if the signal a fluctuates by -20%, two types of phase difference signals with adjacent periods will not be detected during one phase difference measurement period.
Further, even if the signal a fluctuates by 20%, only a portion of one phase difference signal is not detected during the phase difference measurement period.
For example, if the reference period of signal a is 1ms and the tolerance range is set to ±20%, the fluctuation period is 0.8n1
The range is from S to 1.2rT1S. Therefore, the upper limit of the phase difference measurement period is the minimum fluctuation period of 0.8 rns (7) 1.
It is 5 times or less, that is, 1.2 ms or less, and the lower limit is the maximum fluctuation period of 1.2 rns or more. Therefore, the phase difference measurement period according to this example is T. The period is 1.2 ms from the point. Also, during the phase difference measurement period, the signal b of the detection coil is at the signal level L.
You can also start from the point where it intersects. FIG. 4 shows a specific circuit configuration, where 10 is an oscillation coil connected to an oscillator 12 and induces a predetermined oscillating magnetic field, and 11 is an oscillating coil induced by an eddy current generated in the coin to be measured by the oscillating magnetic field. This is a detection coil that detects the magnetic flux caused by the oscillation coil 10 and the detection coil 11, and measures coin data based on the signal phase difference between the voltages and the like of the oscillation coil 10 and the detection coil 11.

1 is a comparator in which the signal a from the oscillation coil is input to the (+) input terminal and a reference signal of a predetermined level is input to the (-) input terminal, and 2 is the comparator in which the signal b from the detection coil is input to the (+) input terminal. A comparator to which a reference signal is input to the (-) input terminal compares the signal a and the signal b with the reference signal level and converts them into a rectangular wave a'' and a rectangular wave b''. 3 is an AN whose one input terminal is connected to comparator 1 and the other input terminal is connected to comparator 2 through inverter 4.
D gate, 5 is a pulse generator that generates a clock pulse d, and 6 is an N-width gate whose one input end is connected to the M-width gate 3 and the other input end is connected to the pulse generator 5. Further, 7 is a counting control device which outputs a reset signal and a counting permission signal for a certain period of time (1.2rr1s in this example) when detecting a falling edge of the output of the comparator 1 while the coin data measurement signal is being input; 8, the counting permission signal is input to one end, and the other input end is . An AND gate 9 connected to the AND gate 6 is a counting device connected to the counting control device 7 so that a reset signal is input to the reset terminal R, and whose counting terminal CL is connected to the AND gate 8. With this configuration, when a coin is inserted, comparators 1 and 2 output rectangular waves a"b", AND gate 3 sequentially generates pulses with a width corresponding to phase difference information, and AND gate 6 outputs a clock pulse from the pulse generator 5'' within this generation period every time this pulse occurs.

In this state, when a coin data measurement signal is introduced from the coin processing control section (not shown) of the vending machine, the counting control device 7
outputs a reset signal to the counter 9 when the output of the comparator 1 falls, and also outputs a period counting permission signal to the AND gate 8. Therefore, the counting device 9 measures the coin data by counting the clock pulses output from the ArSJD games 1 and 8 while the counting permission signal is being generated, that is, within the phase difference measurement period. Then, the coin processing control section determines whether the coin is appropriate or not based on the coin data from the counting device 9. As described above, according to the embodiment of the present invention, the oscillation circuit is configured to fluctuate only up to ±20%,
Falling T of comparator 1 output.

The counting operation is performed in a period of 1.2n1s from .
Therefore, even if the fundamental number of 1ms period fluctuates to the maximum of 1.2rT1S, the output waveform of AND gate 3 will be T. From 0.
61T]S, one piece of phase difference information can be reliably measured within the 1.21T1S period. Also, even if the fundamental wave with a period of 1 ms changes to a minimum of 0.8 m 1 s, A
The output waveform of ND gate 3 is T. 0.4ms・1.2 from
rT1S... However, within the 1.2rT1S period, only phase difference information generated at 0.4 ms is measured, and accurate coin data is measured. Since the counting device 9 is in the counting state with the counting permission signal before the phase difference information is outputted from the AND gate 8, it is possible to count reliably by inputting the phase difference information. (G) Effects of the Invention According to the present invention, a predetermined phase difference measurement period is determined that takes into account fluctuations in the reference waveform cycle within the tolerance range, and this period is determined when the reference wave or detected wave intersects with a predetermined level. By starting from 1 to 2, accurate coin data can be obtained because only one piece of phase difference information is measured within the same measurement period.

[Brief explanation of the drawing]

FIG. 1 is an operational waveform diagram for phase difference measurement, FIGS. 2 and 3 are waveform diagrams showing malfunctions that may occur in conventional phase difference measurement, and FIG. 4 is a circuit diagram according to the present invention. 1●●●●● comparator, 21●◆● comparator,
7... Counting control device, 9... Counting device, 10
...Oscillator coil, 11●●●●●●detection coil.

Claims (1)

[Claims] 1. Equipped with an oscillation coil that forms an oscillating magnetic field at a predetermined oscillation frequency and a detection coil that detects magnetic flux induced by eddy currents generated in the measurement coin in the oscillating magnetic field,
extracting a phase difference signal in the same period between a reference signal related to the oscillating magnetic field and a detection signal of the detection coil, and counting clock pulses with a frequency sufficiently higher than the oscillation frequency within the period of the phase difference signal using a counter; is used to measure coin data, and a phase difference measurement period is set that is greater than or equal to the maximum variation cycle of the oscillation frequency within the tolerance range and 1.5 times or less than the minimum variation cycle, and the reference signal or the A method for measuring coin data, characterized in that the phase difference measurement period is started from a point in time when a detection signal crosses a predetermined signal level.