JPH06282722A - Device for inspection of validity of coin - Google Patents

Abstract

PURPOSE: To reduce the mean power consumption by starting a program only when the presence of a coin to be inspected is detected. CONSTITUTION: A detecting device 316 which starts supplying electric power enabling coin inspecting operation operates irrelevantly to whether an information signal from one of inductive interaction devices (HFI) indicates an accepted coin, and the power supply is substantially performed each time a coin passes along a coin path. Circuit parts 300-302, 315, and 316 which are individually powered up are included, and a controller 316 powers up the respective circuit parts in a period wherein the coin inspecting operation is needed and does not power up them in other period. Therefore, the stand-by power consumption is 0 or extremely low when a coin is expected to arrive, and the power consumption is held minimum even when a coin is in an inspection area.

Description

Detailed Description of the Invention

FIELD OF THE INVENTION The present invention relates to an apparatus for inspecting the validity of coins and related improvements. Throughout this specification, the term "coin" refers to genuine coins, tokens (counterfeit coins), counterfeit coins, substitute coins, washers, and any other item that may be used by people trying to use a coin actuating device. Shall mean.

BACKGROUND OF THE INVENTION Currently, widely used are various electron coin validation apparatus, various in such devices, for example, a coin inserted in the apparatus spaced along the coin track to move There are one or more inductive sensing coils or transmit / receive coils at the position. The sensing coil is connected to an electronic processing circuit in which the magnitude of the signal characteristic (ie frequency, amplitude or phase) that changes according to the nature of the coin as it passes each inductive sensor. It is compared to a predetermined value that indicates one or more specific amount of allowed coins. In this way, the test coin is validated and rejected if the coin does not pass the appropriate tests.

When the switch is turned on, the electronic circuit is almost permanently energized by the power supply. In many applications, continuous power consumption is not important. For example, if this validity check circuit is used in a vending machine that distributes hot drinks, the percentage of the average power consumed by the processing circuit is negligible even when compared to the average power required by the heater and control equipment in the vending machine. can do. However, in certain applications of coin validation devices, such as cigarette vending machines and parking meters that receive power from relatively low power public telephones or batteries, the validation circuit of the type described above consumes. The average power is unacceptably high. In public telephones used in many countries around the world, mechanical coin validity testers are still used in various forms. Although it is desirable to replace these mechanical devices with electronic devices to improve the integrity of the validity test for inserted coins, known electronic coin validity test devices have very low power consumption. It is almost impossible to meet the requirement (for example, 2 mA at 5 volts).

The electronic coin validity test device disclosed in the applicant's British Patent No. 1483192 outputs when the inserted coin passing between the coils along the coin path is made of an acceptable material. It includes a transmitter / receiver inductive arrival sensor adapted to generate a signal. Further downstream in the coin path, the coins are optically tested for their effectiveness, diameter, etc. This is disclosed in the Applicant's British Patent Specification No. 1272560. If the coin passes both the initial induction test and the subsequent optical test, the coin is accepted into the pass passage through the pass gate. In optical testing, a light source is used in combination with an optical coin sensor, such as a photoelectric device. If these light sources are constantly energized, they have a special expected life. Therefore, in order to extend the expected life of these light sources, the light sources are switched on by the output signal from the inductive arrival sensor. A recent trend is towards inductive capacitance techniques for making desirable measurements of coin properties in the inspection area, but as mentioned earlier, the total power consumption in known coin handling mechanisms is acceptable for some applications. It ’s too expensive to do.

US Pat. No. 3,738,469 discloses various forms of coin inspection apparatus in which each coin is first inspected for size by a sensing switch and then a second test is performed by a measuring probe. Coins will only be accepted if they pass both of these tests. This device is continuously powered, but this is a drawback if it relies on battery power. To reduce power consumption, diameter sensing switches can be utilized to switch the current supply network on and off. However, since this switch is activated before the coin arrives at the test area of the measuring probe, the current supply network is switched on rather early, despite these means being activated. Also, diameter sensing switches are set to operate by contact with the edge of a passing coin, but contactless measurement is presently preferred for several reasons including reliability. In addition, the switch, located at a specific distance from the coin truck, can only detect coins of one size, so that if only one coin truck is used, it can Not suitable for use.

[0006] SUMMARY One object of the present invention relates to inductively or capacitively make the necessary measurements on coins is to provide a coin handling apparatus relatively low improved average power consumption.

According to a first aspect of the invention, an apparatus for inspecting the validity of a coin comprises means arranged to define a variable magnetic field or an electric field in the inspection area, between the coin in the inspection area and this field. And a circuit device for determining whether the degree of interaction of the ones is indicative of an allowed coin,
This circuit device is adapted to be turned on in a block according to a program so as to reduce its average power consumption, and the detection device is arranged to start the program only when the presence of coins under test is detected. It is arranged.

Therefore, essentially this coin validity tester requires only a small amount of average power, and when the design of each section of the validation circuit is matched to the minimum power consumption during energization. Power consumption is kept to a minimum and, in addition, the circuit blocks are substantially activated for a sufficient time to do their work. As a result, the standby power consumption is zero or very low while waiting for the coin to arrive, and the power consumption is kept to a minimum even when the coin is in the inspection area. Therefore, overall, the average power consumption is also very low.

According to a second aspect of the invention, an apparatus for inspecting the validity of a coin comprises means arranged to provide a variable magnetic field or electric field in the inspection area, coins in the inspection area and this field. A circuit device for determining whether the degree of interaction between them is indicative of a permissible coin, the circuit device being capable of powering up, and further detecting when the coin has reached the inspection area. A detection device is provided that operates to power up the circuit device only for a limited time when the circuit device makes the decision to accept coins.

Since the circuit device is not powered up until the coin reaches the inspection area of the field providing means, the average power consumption of the coin validity inspection device is low.

Powering up a circuit device either turns on the circuit device or increases the power supply, which may occur block by block, or such that the circuits are powered up simultaneously. You may

In the case of the first and second aspects of the invention, the circuit arrangement, in one embodiment, stores upper and lower limit values indicating the extent of the degree of interaction between the field and any coins that can be accepted. Storage device and a device arranged to determine the degree of interaction between the field and a coin in the inspection area, and a comparison arranged to determine whether the detected degree of interaction is within said range. And device. Low cost storage devices are widely available on the market, but they are non-permanent (ie, the stored information disappears when the power source is removed). Therefore, such a storage device need not be constantly energized. Persistent storage devices may consume more power. However, in the preferred arrangement, the storage device is substantially active for a time sufficient to recall the stored limit value. In this way, it has been found that the average power consumption can be kept very low by using commercially available low cost persistent storage devices.

In another arrangement, the circuit device includes an inductive sensing device installed along the coin path, and thus
In addition to providing a variable field to the test area, the mutual senses the extent of interaction between the coin and the field and achieves a predetermined limit set to allow any allowed coins moving through the test area. By forming the degree of action, the arrival of coins in the inspection area can be determined.

By using only one sensing device which acts to detect the arrival of the coin and also to check the validity of the coin, it is not necessary to provide a separate sensing device to perform these two tasks.

The sensing device may be connected to an oscillating circuit whose oscillating frequency reaches a maximum value as the coin passes through it.

The peak frequency is a position measurement of one or more characteristics of the coin and can be processed to determine if the coin meets certain acceptance criteria. The interaction of the coin with the magnetic field provided by the inductive sensor has the effect of reducing the amplitude of the oscillator output signal, even if the peak frequency is used in the measurement. A common method of measuring oscillator frequency is to add a count so that the oscillator output signal amplitude matches the number of times it crosses a predetermined limit level within a predetermined clock interval. However, the oscillation amplitude must be sufficient, and therefore even for the amount of coins that are about to be known, which gives the maximum rate of decay of the oscillator signal, the minimum amplitude of the oscillator signal exceeds the limit level to correctly determine the oscillator frequency. It is clear that we must be prepared to do so. This requirement can be met by increasing the power supplied to the oscillator following detection of coin arrival. On the other hand, the power required for the oscillator to detect the arrival of coins is relatively low. Therefore,
Average power consumption is also low. The power consumed by a well-known oscillator that does not use this power-up technique depends on the power required to sample the peak frequency, which, as mentioned above, is of some sort requiring a low average power consumption. It is unacceptably high for the above applications.

Turning to another feature of the present invention,
It is known to mount a sensing coil along a coin track and connect the sensing coil to a self-oscillating circuit to test the coin for validity and money. As the coin passes through the sensor, the oscillating frequency or amplitude changes according to the degree of interaction between the magnetic field provided by the coils in the examination area and the coin itself. A detection circuit is used to determine if this change is consistent with a predetermined value indicative of an allowed coin. In order to improve the accuracy of the inspection, the surface close to the coin must always keep a specific distance from the coin and have a specific orientation with respect to the coin during the maximum interaction between the magnetic field and the coin. For this reason, the passage is usually tilted from a vertical plane so that when the coin rolls down the coin track, gravity keeps the coin in surface contact with the side wall of the coin track on which it is moving. There is. Furthermore, within the allowed space limits,
An induction coil should be placed under the coin track as much as possible to provide sufficient distance when the coin passes through the sensing coil so that lateral movement of the coin (eg, non-linear transition or wobble) is reduced as much as possible. Has become. However, the practical limit on the width of the coil validity tester limits the length of the coin track needed to settle the movement of the coin to a relatively short length, which is not due to the light lateral movement of the coin. Often insufficient to completely overcome accuracy. Although using only one sensing coil makes the measurements made with the coil more sensitive, the overall accuracy is limited by the variability of the measurements.

Variations in the measured values can be reduced by connecting another sensing coil mounted on the opposite side wall surface of the coin passage in series or in parallel with the preceding sensing coil.
This further sensing coil has an inductance approximately equal to that of the first coil. It has been found that such an arrangement makes it possible to compensate for any changes in the lateral position of the coin with respect to the sensing coil as the coin passes by, thus considerably reducing the variability of the measured values. However, this correction results in the loss of sensitivity of the coin validity test.

Accordingly, another object of the present invention is to provide an improved inductive sensor device.

According to a third aspect of the present invention, a coin validity checking device includes a coin passage along which a coin passes through an inspection area which receives a variable magnetic field or electric field generated by a sensor device. And is arranged to determine whether the degree of interaction between the magnetic field and the coin detected in the sensor device in the inspection area is indicative of an allowed coin. Means, the sensor device including a pair of inductive or capacitive sensing devices mounted generally opposite each other on opposite sides of the coin passage, spaced apart from each other, the coin along which the passage moves relative to the sensing device. Are arranged so that they remain substantially in a lateral position relative to each other, and the sensing device is connected to the processing device in the circuit, whereby one of the sensing devices is connected. A correction that serves as a measuring device that primarily detects one or more characteristics of the coin, depending on the degree of interaction between the field and the coin, while the other sensing device acts primarily to reduce measurement variations due to changes in the coin's path of travel. The device is designed so that the inductive value or the capacitance value of these sensing devices are set to different values and measured to increase the ratio of measurement sensitivity to variation.

By proper selection of the relative inductance or capacitance for the sensing device, the ratio of measurement sensitivity to variability can be maximized to maximize overall measurement accuracy. The accuracy of the chosen value depends on the range of lateral movement changes that occur. The larger this is, the higher the ratio of the inductances of the two sensing coils. The inductance ratio depends on the surrounding conditions,
It can be as low as 10% or as high as 90%.

Induction coils can be connected in series or in parallel with each other to help or oppose mutual inductance. If these coils are connected in series, the measuring coil will have a larger inductance, and if they are arranged in parallel, the measuring coil will have a smaller inductance. Normally, the coin passage is at a shallow angle to the vertical plane (approximately 10
Therefore, the coin rolls down the coin passage while making almost face contact with one of the side walls of the coin passage as much as possible. The measuring coil is made to react mainly. The measuring coil is mounted on one wall surface according to the characteristics of a particular coin, and the coin moves while making surface contact with this wall surface. Alternatively, it may be provided on the far wall surface. For example, when measuring the thickness of a coin, the measuring coil will be mounted on the far side wall, while when measuring the material of the coin, the measuring coil will be mounted on the near side wall. .

Similar considerations apply if the sensing device is a capacitive element.

With reference to the fourth aspect of the invention, techniques are known for testing coin effectiveness for significant dependence on material composition. In one known technique, an electromagnetic signal is transmitted through the coin and the attenuation factor in this signal is measured. For that purpose, a transmitting coil and a receiving coil are required on both sides of the coin track. This technique has two major drawbacks. First, some commonly used coin materials have a fairly large variation in the decay rate, which is often the case even for a set of coins in a particular country, traditionally using more than one signal frequency. And made an appropriate decision. For example, a transmission frequency of 2 kHz is particularly suitable for copper, aluminum, mild steel and nickel, whereas a frequency of 25 kHz is required for brass, Kyupra nickel and non-magnetic stainless steel. The need to use two frequencies means that either two pairs of transmit and receive coils should be used, or two frequencies should be mixed in the transmit coil and separated by a receive coil with an analog filter. I have to. Such analog circuits are expensive and have relatively high power consumption. Second of this measurement technique
The major drawback of is that in the case of coins consisting of layers of different materials, at the frequencies conventionally used, the effects of different materials are averaged out. As a result, in the case of a 5 franc coin consisting of a nickel-coated Kyupra nickel core and a 5 Maruk coin in which the nickel core is wrapped in Kyupra nickel, it is difficult to use the attenuation of the electromagnetic signal to distinguish these two coins. is there.

In another example, the phase difference between the transmitted and received signals is measured rather than the signal attenuation factor. Although this technique has some advantages, its major drawbacks are the same as with the attenuation technique. That is, more than one frequency is used to perform a good analysis over the range of materials used in the coin, which also requires two channels and an analog filter.

Fluctuations in measuring the transmission attenuation factor at a constant frequency result in measuring the frequency that gives a constant attenuation factor using a voltage controlled oscillator. Over the entire range of coin materials used, the transmission frequency is approximately 100 Hz to 10 Hz.
Must change to 0 kHz. A voltage controlled oscillator that can rotate rapidly over this range has a low frequency oscillator (1 MHz) and 0.8 MHz to 1 MH.
It can be obtained by using voltage controlled oscillators that can operate over the z range and by mixing the outputs of these oscillators and separating them into different frequencies. Although the combined output is digital and therefore suitable for programmable validity checking, its system bandwidth and power consumption make this technique largely unsuitable.

British Patent Specification 1255492 discloses:
Each coin goes through a number of tests, one of which is 1
An apparatus for testing and accepting or rejecting a coin, an inductive test using a coil connected to a bridge sensing circuit energized from a 00 kHz oscillator is disclosed. The induction test examines the electromagnetic properties of the coin so that the bridge circuit is balanced only by the allowed coins. Coins that do not balance the bridge are rejected. This device was specially designed to recognize British 6d, 1 /-and 2 /-coins and the alloys used to make each of these three types were the same. Therefore, this test is designed to know a particular coin material. In this test, homogeneous coins made of different materials can be distinguished, but sandwich-structured coins can distinguish the coin material they are trying to know due to the "averaging" effect of different layers of coin material. It produces a reaction that cannot be done.

The object of the present invention is to use coins of the same size but of different constructions, for example using only one frequency, eg
An object of the present invention is to provide a device capable of more reliably distinguishing sandwich coins from homogeneous coins.

According to a fourth aspect of the present invention, the device for inspecting the validity of a coin provides a coin inspection area in which the coin can be moved and an oscillating electromagnetic field to the coin in the inspection area. An inductive sensor device that responds to the extent of interaction between the field and the coin, and a processing device that is arranged to determine, according to the response of the inductive sensor device, whether the extent of interaction represents an acceptable amount of genuine coins. And the direction of the field is such that the coin penetrates in a direction substantially perpendicular to the plane of the coin,
The center skin of the coin, although the skin depth of the field in the coin is below the surface coating depth of the coin when the frequency of the oscillating field is in the inspection area for each true coin of each amount the device allows. It's not as deep as.

According to a related feature of the invention, there is provided a method of testing the validity of a coin, the method comprising:
The coin is moved to the inspection area and is subjected to an oscillating electromagnetic field by the inductive sensor device, and this inductive sensor device responds to the degree of interaction between this field and the coin, and the degree of interaction indicates the allowable coin according to the response of the inductive sensor device. It is determined whether or not there is an oscillation field frequency, and the direction of this field is such that it penetrates the coin in a direction substantially perpendicular to the surface of the coin, and the frequency of the oscillation field is acceptable for this device. When a genuine coin of each amount is present in the inspection area, the depth of the skin inside the coin is below the depth of the coin's surface coating, but not the depth to the center plane of the coin. Not chosen not to.

The "skin (skin) depth" used in this specification means that the current density is 1 / e (where e is an exponential function), that is, 36.8% of the current density or field density on the surface of the coin. Is defined as the depth below the surface of the coin.

The accuracy of the choice of field frequency depends on the particular coin one is trying to know, but normally the oscillating field frequency has an upper and lower limit in the range of approximately 80 kHz to approximately 200 kHz.

The selection of a particular frequency makes a lot of sense.
For very high frequency oscillators (eg, 1MHz), the skin depth (the penetration of electromagnetic waves into the coin) is very small, so the transmit and receive technology is impractical, and even inductive sensing technology does a validity check. Is significantly affected by the surface material of the coin. The skin depth is a function of the frequency of the electromagnetic field and of the conductivity and magnetic permeability of the material penetrating the electromagnetic waves. Thus, it is clear that at very high frequencies it is not possible to distinguish between sandwich coins and coins made entirely of the same outer layer material.

It is also known to use a low frequency (eg about 2 kHz) where the "skin effect" is negligible and the strength of the electromagnetic waves in the coin material is not so attenuated. At these frequencies, the different effects of the dissimilar materials used in layered coins tend to be averaged in both transmission and inductive sensing technologies, and multilayer coins have the effect of electromagnetic waves caused by heterogeneous coins. Sometimes coins are indistinguishable from coins made of the only material that has the same average effect. Therefore, such techniques cannot achieve satisfactory results under certain circumstances.

On the other hand, as already understood, the magnetic field frequency is set to an appropriate value, for example, the upper and lower limits are approximately 80 kHz.
Or by choosing in the range of almost 200 kHz,
The magnetic field will almost penetrate the area under the core below the surface area of the coin, but will hardly reach the center of the core. In this way, by properly selecting the oscillation frequency, the skin depth penetrates the outer layer of the sandwich structure coin to reach the region outside the core, and can be distinguished in the attenuation rate that occurs in, for example, 5 franc coins and 5 mark coins. There will be a difference. Of course, the exact value of the frequency selected will depend on the particular material from which the coin is made. A frequency of about 120 kHz is considered suitable for many coin sets, including numerous sandwich coins and homogeneous coins made of quite different materials that are commonly used in the world today.

The inductive sensing device, which forms part of the oscillator circuit whose frequency and amplitude change according to the degree of interaction between the oscillating magnetic field and the coin, minimizes the effects of unwanted parameters such as temperature effects, frequency drifts, etc. To keep the limit, it may be preferable to measure the ratio of the oscillator output voltage to the minimum output voltage by the coin when there is no coin.

According to a fifth aspect, the invention relates to the conversion of alternating current signals into direct current signals, which results in very low power consumption and high accuracy.

According to a sixth aspect of the present invention, the first and second
Circuit and a device for alternately applying positive and negative half cycles of a sine input signal to these two networks, a smoothing device for converting each half-wave signal into a DC signal in each branch network, and two branch circuits A rectifying circuit is provided which includes a device for combining these DC signals from the network to produce an output signal whose amplitude is equal to the sum of the coefficients of the two DC signals.

Detailed Description of the Embodiments The coin validity checking device to be described below with reference to FIGS. 1 and 2 does not have an integrated credit function or mechanism control (eg, change-gibbing) function. It is only possible to check the validity of the inserted coins, for example to identify coins up to 6 different amounts. To this end, the device has six output terminals GP (FIG. 4), and at one of these terminals an acceptable coin of one of the six identified amounts is inserted into the device. , And will pass one signal to display the amount of coins after passing it. In addition, an allowance signal appears at terminal Q, which can be used, for example, to activate a coin pass / fail gate to put a coin into a passing coin chute. Alternatively, if the coin is not determined to be a pass, no signal appears at terminal Q and the pass / fail gate directs the coin to the reject coin chute.

Referring to FIGS. 1 and 2, the coin validity checking device includes an inlet hopper or slot position at the top of the casing 2 through which coins are dropped.
The coin moves downward under the action of gravity and collides with the energy dissipation device 3. This energy dissipator absorbs the impact energy of a coin without bouncing it. Therefore, the coin begins to roll under the effect of gravity along the downwardly inclined coin track 4 at position 7 and the three inductive sensors HF1, LF.
And HF continuously. The first sensor HF1 includes two circular coils, one coil for each side of the front and rear spaced side walls 5, 6 (see FIG. 2), one on each side of the coin path. These side walls together with the coin track 4 form a coin passage. As clearly shown in FIG. 2, the side walls 5 and 6 are inclined rearward at a shallow angle (for example, about 10 degrees) from the vertical plane so that when the coins sequentially pass the sensors HF1, LF and HF. The surface contact with the side wall 6 is made as sure as possible. The bottom edge of the HF1 coil is the coin track 4
It is separated slightly above. The diameter of these coils is smaller than the smallest coin they are trying to identify, so that the "diameter effect" is minimized. Similarly, the second sensor LF comprises two circular coils, one mounted on the side wall 6 and the other mounted on the front side wall 5, both coils having their lower edges. Are located slightly above the coin truck 4. The diameter of these coils is smaller than the smallest coin. The third sensor HF is mounted on the side wall 6 and comprises only one coil. However, this coil has an elliptical shape and is arranged so that its main axis extends substantially upward with respect to the coin track. As shown, the lower edge of the sensor HF2 is located above the track 4, but it may be located below it.

The sensors HF1 and HF2 are connected to self-excited oscillation circuits 300 and 301 (FIGS. 3 and 4), respectively.
These oscillator circuits oscillate at a particular idle frequency when no coins come from the test area of the device. In each case, the idle frequency is a high frequency (eg 500-1500 kHz). When the coin rolls down the track 4 toward each sensor and enters the oscillating magnetic field by the sensor, an interaction occurs between the coin and the oscillating magnetic field. This causes a shift in the oscillation frequency of the self-excited circuit, reaching a maximum when the coin faces the sensor. The oscillation frequency then begins to decrease continuously as the coin passes through the sensor, eventually returning its frequency level to its previous idling level. Sensors HF1 and H when coin 7 is rolling down on track 4
Oscillation frequency waveforms generated in F2 are shown in FIG.
It is shown in (e). The coin also absorbs energy from the oscillator circuit, thereby dampening this circuit and reducing the amplitude of its oscillating voltage. The decision control circuit examines the peak frequency shift, but is designed to minimize the voltage swing reduction. To do this, see Figure 3,
A detailed description is given below with particular reference to FIG. Thus, for a sensor, the peak frequency shift starting from its idling frequency will depend on several characteristics of the coin, such as diameter, material, thickness and surface detail. However, each of the sensors HF1, HF2 is designed to be primarily responsive to only one particular characteristic due to its size, shape, alignment with the coin track and oscillation frequency. In this way, the sensor HF1 is primarily sensitive to the thickness of the coin. On the other hand, the sensor HF2 mainly responds to the diameter of the coin. HF
When processing the 1 and HF2 frequency signals, a comparison is made to determine if the peak frequency withdrawn from each coil is consistent with a set of predetermined upper and lower limits that represent a certain amount of allowed coins. .

The sensor LF is also connected to the self-excited oscillation circuit 300 (FIGS. 3 and 4), but this oscillation circuit oscillates at a considerably low frequency. For the specific reasons explained below, this frequency has an upper and lower limits of approximately 80 kHz and 200
It is chosen to be at a frequency in the range of kHz, preferably about 120 kHz. In the case of the sensor LF, a coin passing therethrough and rolling down the track 4 will cause a frequency change and amplitude attenuation of the oscillation output signal of the circuit 302, in which case the frequency change is small and can be ignored. , Instead, a comparison is made to determine if the signal amplitude at the peak decay rate is consistent with a group of upper and lower limits that match the allowed coins of the identified amount. The sensor LF is primarily responsive to the material properties of the coin. When the validation (judgment control) circuit determines that the coins that have passed the sensors HF1, LF and HF2 have passed an appropriate combination test for any given coin amount identified by this coin validity checking device. In fact, this circuit produces a pass signal at terminal Q (FIG. 4). A pass signal does not occur when one or more tests fail. The presence or absence of a pass signal at terminal Q is used to control the position of the pass / fail gates as described above.

Referring to FIG. 3, when the determination control circuit is turned on for the first time when no coin is present, no voltage signal is applied to the external bias input section I of the oscillation circuits 301 and 302 in LF and HF. However, the HF1 circuit 300 is set to a standby or idling state because the voltage of the power supply 304 is constantly applied to the internal bias section circuit thereof. In this state, HF
One oscillator 300 has a small amount of current, for example about 5 Volts to about 1
An electric current smaller than that of a milliampere is received from the external power supply 304. The HF1 oscillator circuit is a resistor circuit (for example, a resistor) 3
05 to the return terminal of the power supply. Circuit 3
05 is connected in parallel with a branch network, which when the electronic switch 307 is closed by the voltage signal on line 500, is connected in parallel with the resistor circuit 305 (eg, a resistor circuit). ) 306. The electronic switch 307 is opened in the HF1 standby mode.

Power-up electronic switch 308, when closed by the "power-up" signal on line 317, provides power from power supply 304 along line 309 to close switch 307 and along power-up line 310. Through bias network 311 to HF2
Oscillator 301, low frequency oscillation circuit 302, amplifier 312,
Power is supplied to the rectifying / smoothing circuit 313 and the voltage / frequency converter 314. Line 3 via bias network 311
The power supplied to 10 is HF2, LF oscillation circuit 301,
Activate 302. Further, when the switch 307 is closed and the resistance circuit 306 is connected in parallel with the resistance circuit 305,
The effective resistance between the oscillating circuit 300 and the power supply 304 between the return terminals is reduced, which causes the oscillating circuit 300 to step up from the idling or standby state to the fully energized state. This increases the oscillation amplitude.

The output signal from the LF oscillation circuit 302 is buffered in the amplifier 312 and then sent to the rectifying / smoothing circuit 313. The rectifying / smoothing circuit 313 generates a DC signal proportional to the magnitude of the output signal of the oscillation circuit at the output section. This analog signal is converted into a corresponding digital frequency signal in the voltage frequency converter 314. The amplifier 312 acts to insulate the LF oscillation circuit from the rising of the rectifying / smoothing circuit 313.

Programmable persistent storage (PRO
M) 315 stores upper and lower limit values for each of a number (6 in this example) of different coin amounts designed to be identified by the decision control circuit. PRO
M315 is energized at input pin y by power supply 304 when electronic switch 319 is closed by the "PROM-enable" signal generated on line 318. The operation of all components of this validation circuit is controlled by a large scale integrated circuit (LSI) 316. This large-scale integrated circuit includes oscillator circuits HF2 and H, respectively.
Output line 50 of F1 and voltage frequency converter 314
It has input parts a, b, c connected to 1, 502, 471. This LSI handles input data received according to a predetermined program (the flow diagram of which is shown in FIG. 8), generates a "power up" signal on line 317 and "PR" on line 318 at the appropriate time.
The "OM-enable" signal is generated to read the set of upper and lower limits stored in the PROM. LSI is HF
1, it also operates to compare the measured value of HF2 with the limit value read from the PROM to determine whether each coin under test is an acceptable coin of the identified amount.

Referring to FIG. 4, terminals A, B serve to connect the return terminals of the power supply and external power supply 304 (FIG. 3) to the validation circuit. Terminal A is supply voltage line 4
00 and terminal B is connected to the negative potential (0 volt) line 402.

The HF2 oscillator 301 has lines 400, 40
It is connected between two. The oscillator circuit 301 is suitably a Colpitts circuit, the emitter of the transistor of which is connected to the negative potential line 402 through an inductor 406 and a resistor 405 arranged in series. The oscillator is activated when a bias signal is applied to the transistor base on line 407. The HF2 oscillating circuit output unit 503 is connected to the capacitor 4 via the line 501.
08 and a buffer circuit 409 are connected to the input section b of the LSI 316. This buffer circuit 409 allows HF
The output signal of the 2-oscillation circuit 301 can be monitored at the output terminal D without affecting the oscillation frequency.

The two coils of the sensor HF1 (in this embodiment, arranged in parallel and facing each other) are connected to the coil pits oscillation circuit in the same manner as the sensor HF2. However, as already mentioned, the oscillator HF1 is connected to the resistor 4
10, diode 411 and positive and negative voltage lines 400,
It is always at least idling due to the bias voltage signal applied to the oscillator transistor base from a voltage divider that includes a series arrangement of resistors 412 connected between 402. The effective resistance of the branch connecting the emitter of the oscillator transistor to the negative voltage line 402 is reduced by a power-up signal applied to the base of an electronic switch 307 (which takes the form of a switching transistor) to cause resistor 306 to resistor 305. Can be connected in parallel with. As a result, the HF1 oscillator circuit 300 is switched from the idling, that is, the standby state to the full power state. The ratio of the capacitances of the two capacitors 580, 581 of the HF1 oscillator tuning circuit is chosen to be about 3: 1 to minimize the attenuation of the output signal from the oscillator output 505. The output of the HF1 oscillator is a capacitor 41
3 and the buffer circuit 414, and is connected to the input section a of the LSI 316. This buffer circuit 414 operates continuously so that the oscillation frequency of the HF1 oscillator can be monitored at terminal c without changing its value. A capacitor 415 connected between the base of the oscillator transistor and the negative voltage line 402 acts as a decoupling capacitor for this transistor. Furthermore, the voltage line 400,
Capacitors 403, 404, and 416 are connected between 402, and these capacitors perform high-frequency filtration and energy supplementation. This prevents fluctuations in the supply voltage, but without it would upset the operation of the validation circuit.

The base of the switching transistor 307 is connected to the negative line 402 through the series arrangement of the resistor 708 and the capacitor 709, and the electronic switch 3
08 (also in the form of a switching transistor) receives a voltage signal along line 500 through transistor 710 when turned on by a "power up" signal applied from LSI 316 to the base of line 317. It is arranged. This electronic switch 3
19 includes a first switching transistor 420, which the LSI 316 places on the line 318 "PROM".
Sending a voltage signal to the base of another switching transistor 421 when generating the "enable" signal and also switching power to the input y of the PROM. Transistor 4
The voltage signal applied to the base of 21 simultaneously
A signal is given to the enable input part x of the M315, and the LSI3
16 enables the PROM and read stored data to be addressed.

A capacitor 424 connected between the lines 400 and 402 stores energy from an external power source, and when the transistors 420 and 421 are on, the PROM 315.
This stored energy can be used to increase the power delivered to the.

The PROM 315 has seven address input sections A.
0-A6, and these address input units are LSI31
6 requests the PROM and is stored in the PROM,
It makes it possible to provide on the output lines D0-D3 a signal indicating the upper and lower limit heads corresponding to the coin amount combined with the appropriately decoded address lines A0-A6. The address input units A0-A5 are connected to the corresponding coin output terminals I, K, L, M, N, P.
The address line A6 is connected to the terminal Q. PRO
The M address signal and the output signal are sent on lines A0-A6 at different times. By using multiple operations to select several sets of data on lines A0-A6
Reduces the number of pins required, and thus the cost.

The LSI operation follows a program, and this program proceeds according to a clock pulse from a clock circuit 422 which simultaneously supplies two sets of clock pulses at frequencies of 0.5 MHz and 250 Hz. The reason for using the two sets of clock pulses is that the different timing waveforms required by the LSI 316 are spread over a wide range, and these two clock pulses are provided by using two considerably different base clock frequencies and an appropriate voltage divider. This is because it is convenient to generate. The LSI gives a signal to the output terminal G and makes it possible to monitor the clock pulse rate.
Furthermore, the LSI has a setting input d with a switch 423, as shown, for preselecting one of two different reach / escape limit levels for the HF2 sensor.

The low frequency (LF) oscillator circuit 302 is similar to two high frequency oscillators (HF1, HF2) and includes a Colpitts oscillator. In this embodiment, the two coils of the LF sensor are arranged in parallel so that mutual inductances face each other. The oscillator transistor comprises a series arrangement of a resistor 429, a diode 430 and a resistor 431 (which together constitute the bias network 311), and further two decoupling capacitors 432,
433 is provided. These capacitors, along with the series networks 429, 431, are connected to a switchable supply line 434 adapted to receive the power-up voltage when the LSI generates a power-up signal on the line 317 when supplied with power from the line 310. It is connected between the negative voltage line 402 and the negative voltage line 435 having the same potential. The emitter circuit of the Colpitts oscillator is a variable resistor 4
36 and fixed resistor 7 coupled with inductance 730
28 and 729, it is possible to set the oscillation amplitude within the dynamic range of the validation circuit with or without coins. The oscillating output signal from circuit 302 is sent to amplifier 312. This amplifier, as shown, is in the form of an emitter follower buffer, the output of which is sent along line 437 to rectifying and smoothing circuit 313 and across capacitor 438 to differential amplifier 439. This differential amplifier acts as a zero-crossing detector and serves to control the operation of circuit 313.

As shown in FIG. 5, the rectifying / smoothing circuit 313 includes two CMOS switching devices 410, 441 arranged in parallel branches 510, 511 connected to the output of the emitter follower buffer 312. Each branch has one of the branches 510, 511 connected to a line 444 held at a reference voltage, and another CMOS switching device 443, 442, two branches 51.
0, 511 includes filter networks 445, 446 and an input includes an integrating differential amplifier 447 which receives the output signals from these filter networks. A sine output signal from the emitter follower buffer circuit 312 is shown in FIG. 6 (a). The output of zero-crossing detector 439 is connected to four CMOS switching devices via NOR gate 448 (FIG. 4), and therefore power-up line 31
These switching devices are controlled only when receiving the enabling signal from line 7 on line 7. Zero-crossing detector 439 allows CMOS switching devices to be paired, ie, 440, 442, 441,
443, so that the positive half-cycle of the signal on line 437 appears at the input leading to filter network 445, while the negative half-cycle appears at the input leading to filter network 446. These signal waveforms are shown in Fig. 6, respectively.
It is shown by X and Y in (c) and (d). On the other hand, the switching waveform from the zero-crossing detector is shown in FIG. 6 (b). As shown in FIG. 4, the filter networks 445, 44
An RC filter 6 generates an average DC level from each of the waveforms X and Y, which is sent to the corresponding input of the integrating differential amplifier 447. This integration provides a second filtering stage and the presence of a differential amplifier arithmetically adds the magnitudes of the positive and negative inputs to produce a negative DC output voltage, which appears on output line 450.

When amplifier 447 receives a substantially DC input signal, it does not require large bandwidth or high slew rate. Zero-crossing detector 439 has low power consumption and results in a switching device having CMOS devices 440-443. These CMOS devices are NOR gate 448
The power-up signal applied on line 530 to one of the inputs is activated when the LSI produces a negligible amount of power consumption.

The use of differential amplifier 447 is important for measurement accuracy. Consider an input waveform that has a DC offset component as the reference supply voltage. This DC level is applied alternately at x and y, giving a DC component of the same polarity, and the resulting output from the differential amplifier is zero. CMOS analog switch 440
-443 does not need to have an ON resistance value. What if
The ON resistance values for the four devices are similar,
This is unique when they are integrated in one device (which is preferred). By using four switches and a low impedance buffer 312, the output of the filter network always exhibits a constant low source impedance. Therefore, the difference between the measured values is always accurate.

In this way, the rectifying / smoothing circuit 313 is
The DC signal is applied from the input limiting waveform while keeping the power consumption very low. The same result cannot be achieved with a single diode rectifier. This is because there is an offset voltage due to the forward voltage drop of the diode and the temperature coefficient of the voltage. A precision rectifier with two diodes and an operational amplifier eliminates these sources of error, but this operational amplifier has a differential frequency (ie, 100 × 12).
This requires a product of a gain bandwidth of about 100 times (0 kHz = 12 MHz) and a fast slew rate. The circuits described in connection with FIGS. 4, 5 and 6 eliminate the need for these requirements.

During the duration of the power-up signal generated by the LSI, the negative DC voltage signal on line 450 (FIG. 4) is sent directly to the CMOS switching device 453 along the first branch 455 to drive the unity gain inverting amplifier 451. It is sent to the second CMOS switching 454 via line 456 along the containing second branch. These CMOS switching devices are alternately switched by a common digital signal on output line 457. The switched voltage from switching device 453 or 454 is sent to the non-inverting input of integrating amplifier 472. The integrating amplifier produces a ramp output voltage that increases or decreases according to the algebraic sine of the input voltage signal. This ramp signal is compared in a voltage comparator 452 with the reference voltage at its inverting input. This voltage is applied to resistors 458, 4
Comparator 4 returned through resistor network including 59
The output signal of 52 switches between values + V _t , -V _t .

The reference voltage V _ref is the power-up line 3
Power up line 310 and negative line 435 from operational amplifier 461 having an inverting input biased from 10.
Is provided on line 460 through a voltage divider network including equivalent resistors 465, 466 connected between. Capacitors 463, 464 are decoupling capacitors. The reference voltage on line 444, the reference voltage of zero crossing detector 439, the amplifier 451 and integrator 456, the voltage on the non-inverting input and the reference voltage ± V _t are all derived from the reference voltage V _ref on line 460.

The operation of the voltage frequency conversion circuit 314 will be described below with reference to FIG. Voltage frequency converter 314
Is sent to line 450 as an input voltage to and is shown at the DC output voltage -V _in from rectifying and smoothing circuit 313 (V _ref on line 460 is shown as 0 volts).
Consider time t ₀ when the voltages on branches 455, 456 at the inputs to switching devices 453, 454 are shown in FIGS. 7 (a) and (b), respectively. At this time, the output signal of the comparator appearing at the output of the NOR gate 470 has a negative value −V _x [FIG. 7 (e)], and this signal is simultaneously applied to the control inputs of the switching devices 453, 454, Integrating amplifier 47 while holding the −V _in voltage
The voltage + V _in is applied to the inverting input section of No.2. FIG. 7C shows the input voltage to the integrating amplifier 472. This amplifier is
Therefore, the ramp voltage V with the value -V _int / RC at the input
_out [see (d) of FIG. 7] is given. Here, RC indicates the effective resistance value and capacitance value of the integrator 472. Integrator 4
The output voltage of 72 is compared with the limit voltage in voltage comparator 452. This limit voltage then has the value −V _t ,
Applied to the inverting input. When the output ramp voltage is equal to the reference voltage (at time t ₁ ), the output of the comparator 472 changes from the lower side to the higher side and becomes a new value + V _x [(e) in FIG. 7]. −V _x is approximately the same potential as line 435, while + V _x is approximately the same potential as line 310. Comparator 45 with resistance network 458, 459
The change in the output voltage of 2 changes the reference voltage + V _t at the inverting input of the comparator 452. At the same time, the new output of the comparator 452 switches the devices 453, 454 so that the voltage now applied to the inverting input of the integrator 472 has the value -V _in . This is shown in FIG. 7 (c). Then the output voltage of the integrator rises in a stable manner with a slope V / RC and becomes equal to the value + V _t at time T ₂ . Then the circuit switches again and the output of the integrator again falls to the falling ramp voltage. Therefore (power-up signal is L
It should be appreciated that a pulsed voltage signal (during SI) is generated at the output of NOR gate 470 on line 457 and along line 471 to LF input c of LSI 316. As can be seen, the positive and negative slope of the integrator output voltage is proportional to the magnitude of V _in . Therefore, the frequency of the signal generated on the line 471 is equal to the frequency of the LF oscillation circuit 302.
Is directly proportional to the amplitude of the output signal from.

It should be noted that the chosen magnitude of the reference voltage V _ref is not particularly important. This is because it is used as a common reference voltage for the rectifying / smoothing circuit 313, the inverting amplifier 451, the integrator 472 and the comparator 452. It is appropriate to keep the detection circuit linear throughout the dynamic range, with the chosen magnitude being about half the "power-up" voltage on line 310. Also, by using the same input voltage (the output voltage from the rectifying and smoothing circuit 313) for the positive and negative half cycles of the input voltage waveform of the integrator 472, there is no offset in the output frequency signal on the line 471. Please pay attention. That is, when the input voltage V _{in is} approximately zero, the frequency of the signal on line 471 is also approximately zero.

Further, the duration of the LF signal on line 471 is proportional to V _t , which in turn is proportional to the power-up voltage, but V _in increases with the power-up voltage (V _in
Is proportional to the amplitude of the low frequency oscillator output signal), so the output period is almost independent of the power-up voltage.

In essence, the function of the LSI is to determine whether the coin under test is an acceptable coin for the identified coin, in the same manner as it receives signals a, b, c for signals HF1, HF2,
Processing the LF signal. In the case of HF1 and HF2 signals, the LSI determines the instantaneous frequency by counting the number of times the HF signal crosses a preset limit level (called V _{tH in} the description of FIG. 10) at predetermined clock intervals. For the LF signal, the LSI counts the clock pulses generated by the clock circuit 422 during each cycle thereof, thus measuring the instantaneous duration of the LF signal.

Ideally, in order to correct the influence of drift and temperature change, the LSI has an idling level that exists just before and after the HF1, HF2, and LF counts vs. the peak level (that is, a coin is detected in the inspection area of the corresponding sensor). If not), calculate the ratio of the peak values, and PROM315
Compare the calculated ratio against a set of predetermined upper and lower limits read from. In practice, in the case of the HF1 and HF2 signals, each peak count will be quite different from the idle value, so calculating the difference between the peak frequency value and the idling frequency will give a value very close to full correction. However, the attenuated peak LF amplitude for some coin amounts is much smaller than the idle value, so the LSI is programmed to calculate an exponential value for LF counts.

The LF output signal on line 471 is approximately 1:
It is a square wave with a mark ratio of 1, and its frequency changes according to the magnitude of vibration of the LF oscillation circuit 302. In order to accurately measure the peak decay rate of the coin passing through the LF sensor, each measurement sample performed by the LSI should preferably not be longer than 2.5 ms. Therefore,
For 0.1% accuracy, the input frequency would have to be at least 400 kHz. In order to minimize the effects of integrator bandwidth and signal propagation delay through the comparator 452, L sent to the LSI rather than the input frequency.
The duration of the F input signal is measured as indicated above. In a practical example, the maximum period was chosen to be 2 ms, 5
12 kHz clock has a maximum count of 1024 in each period
Is determined to give. This longest period corresponds to the oscillator's minimum amplitude, which corresponds to the coin amount that produces the highest decay. The peak-to-idle ratio calculated by the LSI is chosen to give a full-scale measurement for coins with an 8: 1 decay rate. The minimum period corresponding to the absence of coins is therefore 0.25 ms. This "idle" period is measured over eight consecutive periods to increase resolution and can be measured either before the coin is present or after the coin leaves the measurement field. After measurement, LS
The I316 has two 10-bit binary numbers corresponding to two input periods in the storage area. First binary number (idol)
Is the count number of all pulses generated during eight consecutive idle periods. The second 10-bit binary number (peak) is H
It is a count of the maximum number of clock pulses that occurred during any single input period that existed between the arrival of F1 and the departure of HF2. The LSI performs binary division.

(Peak / Idle) × 512 = Normalized peak

This normalized peak is a 9-bit binary number corresponding to the attenuation rate of the coin, and is the PROM3 in the LSI.
It is compared with a set of upper and lower limit values read from 15.

Size of power-on bolt, 512 kHz
The value of RC in the clock frequency integrator, the gain of the rectifying / smoothing circuit 313, and the absolute amplitude of the LF oscillating circuit 302 do not affect the normalized peak value if the low frequency detecting circuit has a linear response. Steps in which the entire operation of the coin inspection device is performed by the LSI (80
0-842), the description will be made below.

Now, assume that the validation device is off and there are no coins anywhere. Then the device is turned on. In the following description, in order to facilitate understanding of the operation of the LSI, the HF1, which is sent to the LSI,
The description will be given assuming that there is only one mode in which the input signals of HF2 and LF are handled.
More complex techniques, such as dealing with LF signals on 1 can also be employed.

Step 800 The LSI resets all registers, latches, timers and sequencers.

Step 801 The delay time (for example, 256 ms) times out,
The HF1 oscillating circuit is set to its standby, i.e., idling mode, for a sufficient time and normal oscillation frequency.

Step 802 Next, the HF1 idle count is stored in the LSI.

Step 803 In the above procedure, the LSI repeatedly stores a count corresponding to the number of times the oscillator signal crosses the V _tH threshold [FIG. 10 (d)] at a predetermined clock interval. At each count, the LSI calculates ΔHF1 equal to the HF1 count minus the HF1 idle count stored in step 802.

Step 804 Each calculated value ΔHF1 is ΔHF1T [HF1T (see FIG. 1
Count corresponding to 0 (see (a)) minus HF1
Equal to idle count] and if this ΔH
If F1 count is not greater than ΔHF1, LSI
Returns and repeats step 803 for the next HF1 count. However, if the ΔHF1 count exceeds the ΔHF1T count, the LSI proceeds to step 805. Obviously, step 804
Is actually searching for the arrival of coins. In particular, note that the electronic switches 316 and 308 are turned off before the arrival of coins is detected. This is line 31
This is because the power-up signal is not generated by the LSI in FIG. 7 and therefore the LF and HF2 oscillation circuits 302 and 301 are deenergized. In addition, LS on line 318
The PROM 315 is also de-energized because the "PROM enable" signal has not been generated by I316. Therefore, only the current drawn from the power supply is needed to keep the HF1 oscillator in standby and power the LSI. This total current will be less than about 1 mA at 5 volts, for example.

Step 805 The LSI sets the power-up latch. The power-up latch is adapted to generate a power-up signal on line 317 to provide full power to the HF1 oscillator and energize the circuit for LF and HF. At the same time, the program steps 80 for the HF1 signal.
6 and proceeds to step 826 for the LF and HF signals.

Step 806 : The HF1 timer set so as to time out a predetermined time (256 ms in this example) is started. This HF
The purpose of one timer will be described later.

Step 807 Since the arrival of coins has been detected, each successive ΔHF1 count is checked for the highest ΔHF1 value received. If the current value exceeds the previously mentioned peak value, this current count is substituted as the new peak value.

Step 808 A determination is made as to whether each ΔHF1 count exceeds the ΔHF1T count. If so, the program proceeds to step 809, but if not (ie, HF1 departure is detected), the program proceeds to step 810.

Step 809 If the HF1 timer times out, the program proceeds to step 811. Otherwise, the program returns to step 808 and repeats step 808 for the next ΔHF1 count. HF1 timed period (2
56 ms) is chosen so that HF1 departures will be detected within the HF1 timed period for all allowed coins. However, HF1 when the device is not in use
It is also conceivable that a factor such as idle drift will raise the ΔHF1 idle count above the ΔHF1T threshold. In this way, the LSI erroneously detects the arrival of the coin, and further, the HF1 leaving is not detected at all. Under these conditions, LSI resetting would not be possible without the HF1 timer. However, even in the abnormal state of the idle count of HF1 rising to the HF1T threshold, the program proceeds to step 81 after the delay time of 256 ms.
Go to 1.

Step 811 The new HF1 idle count is stored.

Step 812 All registers, latches, timers and sequences are reset and the program returns to Step 803 to begin the search for another coin to arrive. Under normal conditions, the program proceeds directly from step 808 to step 810.

Step 810 The HF1 timer is reset.

Step 813 The peak ΔHF1 count determined in step 807 is compared to several sets of HF1 upper and lower limit values stored in the PROM, and this peak count is equal to 1 of the discriminating amount.
Determine if it is between two upper and lower limits.

Returning to the signals at step 826 LF, HF2, the program delays for a preset period (eg 32 ms) before proceeding to steps 814 (LF) and 815 (HF2) at the same time. This delay causes transient phenomena in LF and HF2 oscillation to
Turn off before F and HF2 measurements are taken.

Step 814 The LF count corresponding to the number of clock pulses counted in each cycle of the LF signal is repeatedly stored.

Step 816 A search is made for peak LF counts of the counts received.

Step 815 The HF2 idle count is accumulated.

Step 817 The LSI corresponds to the number of times the HF2 signal crosses a predetermined threshold level in the clock interval. HF2 counts are repeatedly accumulated and HF is calculated for each HF2 count.
Calculate a value ΔHF2 equal to 2 counts minus HF2 idle count.

Step 818 The LSI stores the maximum of some HF2 counts as the peak count.

Step 819 The LSI determines ΔH from the ΔHF2 count larger than HF2T.
Search for transients up to ΔHF2 count less than F2T. If the transient condition is not met, the program returns to steps 816, 818 to find the peak LF,
Continue the search for HF2 counts. If the transient condition is met (ie, HF2 leave), the program proceeds to steps 820 and 821 simultaneously.

Step 820 The ΔHF2 peak count is compared to the upper and lower limit values of ΔHF2 for different coin amounts read from the PROM to see if the HF2 peak is between the limit values for any one of the identified amounts. Decide whether

Step 821 The LSI accumulates the LF idle count. In this regard, it should be pointed out that in the case of HF1, HF2 measurements, it is necessary to accumulate the idle value before the coin reaches the inspection area. This is because the idle value is needed for the calculations performed when the coin is in the inspection area. However, in the case of LF, it is the ratio of LF peak to LF idle, so the idle value can be measured before or after the coin is in the test area. In this example, after the coin leaves the inspection area, the LF
I find it more convenient to measure idols.

Step 822 The LSI calculates the LF peak count determined in step 816 to the LF idle count ratio determined in step 821.

Step 823 The LSI compares this calculated LF ratio with the upper and lower LF ratio limits for different coin amounts read from the PROM.

Step 824 The LSI checks the validity, and steps 813 and 820
HF1, HF2, LF carried out in and 823
Check if each of the tests shows the same amount for the coin under test. If so,
The coin passes, otherwise it fails. The program then proceeds to steps 812 and 825 simultaneously. Step 812 has already been described.

Step 825 The LSI outputs the result of the validity check executed in step 824.

A very important feature of the coin validity checking device described above is that the use of the PROM allows the data stored in the PROM to be modified in order to adapt the device to coin sets of different countries. It means that you only have to change it.

Referring to FIG. 9, various signals and current changes of the validation circuit are shown as a time plot. 9A and 9C show changes in the frequency of the output signals of the HF1 and HF2 oscillators, and FIG. 9B shows the amplitude of the LF oscillator output signal. FIG. 9D shows the total current drawn by the HF1 oscillator and the LSI. This current changes from the idling level to a higher level after the HF1T threshold is reached, this high level lasts for a short time after the HF2 frequency drops below the HF2T threshold and then HF.
1 oscillator returns to idling. The idling HF1 power consumption is very small, for example less than about 1 mA at 5 volts, since even the damping effect of the coin with the highest decay rate when sensing the arrival of HF1 is small. LF, H
The F2 oscillator is energized as long as the HF1 oscillator is running at full power. This is shown in FIG. 9 (e). The total current used by the validation circuit at this time (apart from when the PROM is energized) is about 15 mA at 5 volts. In FIG. 9F, the PROM is the first
Is activated to read out the HF1 limit value during
It is shown that during the second and third periods after leaving HF2, HF2 is first activated and then the limit value of LF is read out. The total current used in the validation circuit is about 50-150mA at 5V, which is relatively high.
M is energized. However, the three periods in which the PROM is activated for each coin are just long enough for the required reading of the limit value and are chosen to minimize the total time the PROM is activated. It is conceivable to replace the PROM with a bipolar PROMS because the power consumption mentioned above is low. CMOS PR
OMSs are commercially available because of their low power consumption, but their cost is generally high and unsuitable. FIG. 9 (g) shows how the total current used (full line) changes with time. The broken line shows a typical value of the average current consumption (2 mA or less at 5 volts). Of course, this value depends on the average time of the intervals for continuously inserting coins into the coin inspection device.

Referring to FIG. 4, the power-up signal is LS.
NOR gate 4 except when generated by I
Note that the outputs of 48, 470, 506 are held at logic "0". This deactivates the circuits downstream of each gate, thus reducing power consumption and nullifying any spurious signals at the other inputs of these NOR gates. In the case of a known coin inspection device in which all electronic circuits are constantly energized, the total current would be as shown by the dash-dotted line, for example. Obviously, therefore, the device according to the invention has a considerably reduced average consumption and can be used especially in applications such as payphones. Also,
Since the circuits other than the LSI are minimized, the cost is reduced and the reliability is increased.

For example, each upper or lower limit value combined with each test (HF1, LF or HF2) for each identified coin amount is a 9-bit number, which is a type of PROM organized by a 4-bit data word. Stored in. Therefore, to read a 9-bit number from the PROM,
It is necessary to use three separate addresses for this PROM. Therefore, in the illustrated embodiment, in the case of a coin validity device that can identify six types of coin amounts,
The PROM can be activated to read the HF1 limit value in 36 consecutive bursts. This is because each number requires three addresses and there are two limit values (upper and lower limits) for each of the six types of coin amounts. PRO
M is organized so that each read can be done in 1 microsecond. Therefore, the total time required to power the PROM to read all limits for the three tests would be 3x36x1 microseconds equal to 108 microseconds. It will be apparent that by addressing the PROM in this way, the average power consumed by the PROM is very small.

The time T _LF [FIG. 9 (b)], T from when the circuit turns on the LF or HF2 oscillator to when the coin enters the inspection area of the sensor LF or HF2.
_{Note that HF2} [Fig. 9 (c)] is possible. During these periods, the LF and HF2 oscillators can be switched on at appropriate times and then settled to a constant idling frequency and amplitude.

For a better understanding of the importance of powering up the HF1 oscillator, refer now to FIG. FIG. 10A corresponds to FIG. 9A and shows a change in frequency of the HF1 oscillator over time. t
_I is the time when the coin interacts with the oscillating magnetic field to increase the frequency and decrease the signal amplitude. At time t _II , the frequency signal reaches the HF1T threshold and the HF1 oscillator is powered up as described above. The frequency signal reaches a maximum at time t _III , then falls again and falls below the HF1T threshold. Finally, at time t _IV , the HF1 oscillator is returned to its idling state.

FIGS. 10 (b) and 10 (c) are preceded by the fact that they are continuously energized at a lower power level [FIG. 10 (b)] and a higher power level [FIG. 10 (c)]. Although not embodying the embodiments of the first and second aspects of the invention described above, it shows the oscillator output signal of an oscillator operating at a frequency corresponding to the frequencies of the HF1 and HF2 oscillators. Figure 10
It should be emphasized that (b), (c) and (d) are purely schematic and the continuous vibration is shown wide enough for illustration. In these figures, the envelope of the oscillation signal is shown by the broken line. "+" And "-" indicate the supply power rail. As already mentioned,
The LSI continuously assesses the instantaneous oscillator signal frequency by counting the number of times the oscillator signal crosses the voltage threshold V _TH within a given period. Figure 10
In (d), a signal waveform of an oscillator that is differentially operated at low power or idling is shown. As can be seen, the peak signal level in the absence of coins in the inspection area is not much greater than the voltage threshold V _TH , so that during time T the oscillator signal is sufficiently damped to cross the threshold V _TH. Disappear. Therefore, during this time, the LSI cannot continue the function of accumulating the count corresponding to the pulse frequency. For this reason, as shown in FIG. 10 (c), the power is set to a sufficiently high level in the known oscillator, and even the most greatly reduced magnitude of the oscillator signal will exceed the threshold V _TH . In relatively inexpensive commercial LSIs, the switching thresholds of the CMOS devices used there are given wide manufacturing tolerances, so the oscillator power should be large enough to generate the maximum signal attenuation, even in the case of coins that produce maximum signal attenuation. We must try to exceed the maximum value. For some oscillator circuits designed to meet this demand, the power consumed when it is idle is too high for applications of the above kind.

FIG. 10 (d) shows how this deficiency can be overcome by using an oscillator that is powered up when the coin reaches the inspection area.
In this regard, it should be particularly noted with respect to FIG. 10 (b) that even in the case of an oscillator operating at low power, at time t _II (coin arrives), the peak of the oscillation signal is still the voltage threshold V _TH. Therefore, the LSI can detect the arrival of coins. Therefore, the HF1 oscillator is designed to idle at low power when there are no coins. Obviously, time t
Up to _II, it requires only relatively low power. At time t _II , the HF1 oscillator is powered up, which increases the magnitude of the oscillator signal, still at threshold V
_It will exceed _TH . The HF1T oscillator need only be powered up for a time T _A , but at the same time the HF2 and LF oscillators are turned off, the HF1 oscillator is “powered down”.
It is more convenient if you do. Otherwise, 2
Two separate control signals would be required. For this reason, the HF1 oscillator in the illustrated embodiment continues to be powered up until time t _IV .

Ideally, the threshold level HF1P
Must be set low enough to allow the coin to be sufficiently crossed before it is in the position of maximum interaction with the magnetic field. This gives the maximum time T _B for the transient decay to disappear before peak decay is achieved. For example, T _B is on the order of milliseconds and HF1
It should be noted that successive cycles with oscillation frequencies on the order of 1000 cycles / 1 ms are much closer together than shown in Figures 10 (b) to (d). However, the procedure shown for explaining the HF1 oscillation signal is provided to help understanding of these figures.

In this way, the HF1 oscillator can actually detect only the arrival of coins to the inspection area in the standby mode, but is powered up so that a sufficient oscillation amplitude can be maintained at the peak attenuation rate. It should be able to perform a quantitative evaluation of the peak frequency and determine if the coin is acceptable.

When the detection device is provided at the only position where the arrival of the coin is detected and the coin is tested, the arrival sensor for detecting the arrival of the coin and the separate measuring sensor operated by the arrival sensor are provided. I would like to point out that it is particularly advantageous because it does not have to be used. Also H
Since the F1 oscillator is not powered up until the coin reaches its test area, the HF1 oscillator is powered up for a shorter period of time, thus “minimizing” the average power consumption of the coin validity tester.

As already described with reference to FIGS. 1 and 2, when the coin track 4 is inclined, the coins are HF1 and L.
It is designed to keep the surface contact with the rear wall 6 as much as possible when passing through the F and HF2 sensors. If you don't do this, the coins will move laterally, causing HF1, L
It may result in inaccurate F, HF2 peak values, failing acceptable coins, or falsely passing bogus coins. In spite of the fact that the coin truck is tilted in this way, it has been found that there is actually a slight change in the coin movement path that passes through the sensor.
This is especially the case when various sensors are provided close to the energy dissipator 3 (FIG. 1) due to space limitations. In order to correct this and reduce the dispersion of measured values,
The HF1 and LF sensors each include a pair of sensing coils, one on each side of the coin track. Figure 11
Referring to, the HF1 sensor includes a measurement coil HF1M mounted on the front wall 5 and a correction coil HF1C mounted on the rear wall 6.
Includes and. In this embodiment, these measuring and correcting coils are connected in parallel. The relative inductances (L1, L2) of the two coils depend mainly on the inductance L1 of the HF1M whose effective impedance exceeds the measurement, and as a result, the oscillating magnetic field generated between the two coils HF1M, HF1C by the measuring coil. Coin 7
It is primarily designed to sense interactions between and. Therefore, the inductance of the HF1M coil is H
It is much smaller than the inductance of the F1C coil. However, it has been found that there is an effect of the correction coil in satisfactorily correcting the influence of the change in the coin movement path on the output oscillation signal from the HF1 oscillator 300. However, compared with the known device in which the inductances of the two coils are equal, the measurement sensitivity is sufficiently high, the dependence on the coin thickness is still high, and the dispersion of the measured values is very small, which is preferable. As a result, the overall accuracy, which is highly dependent on the sensitivity to variability ratio, is improved. In fact, with proper selection of the inductance values of the two coils, the overall accuracy can be maximized. This choice depends on the length of the coin truck in front of the sensor,
Factors such as the angle at which the side wall of the coin truck is tilted from the vertical and the effectiveness of any energy dissipator installed on the top of the coin truck to change the direction of movement of the coin while minimizing rebound of the coin. Depends on. As a typical example, when the component of the lateral movement of the coin is very small, the ratio of the inductance or capacitance of the sensing coil for obtaining the highest measurement accuracy is as low as about 10%. For larger lateral movements, this ratio may have to be chosen to be as high as about 90%.

In another arrangement in which two coils are connected in series, the measuring coil has a much larger inductance than the correction coil and the effective impedance of the two coils must be determined primarily by the inductance of the measuring coil. Will have to.

The same idea is adopted in the case of the LF sensor. However, it is appropriate that the LF measurement coil is mounted on the rear wall 6 and the correction coil is mounted on the front wall. The HF2 sensor consists of a single sensing coil to avoid the effects of almost any thickness. In any case,
By the time the coin reaches a single HF2 coil, any changes in the coin travel path and its effects can be ignored.

In order to recognize the importance of selecting the LF idle frequency described above, the following FIG.
To be referred to.

FIG. 12 shows three coins of the same size (diameter D) and thickness (t ₀ ). These coins oscillate at frequency f ₀ from both sides by two coils of the inductive sensor device. Receive an electromagnetic field H. As mentioned above, this electromagnetic field has upper and lower limits of about 80 kHz and 200 kHz.
Within a range that is z. The frequency f ₀ is preferably about 12
At 0 kHz, the LF coil is oriented so that as the coin passes through the inspection area, the magnetic field is oriented approximately perpendicular to its plane.

With reference to FIG. 12 (a), this first coin comprises a core made of metal X and a coating of metal Y of another kind. The conductivity and magnetic permeability of the metals X, Y are chosen so that the magnetic field will penetrate the metal Y more easily than the metal X. The second coin [FIG. 10 (b)] is a krat coin having a coating of the same thickness as the first coin, but in this case, the core is made of metal Y and the coating is made of metal X. However, in the third coin [Fig. 10 (c)], the coin is generally homogeneous and consists of only one kind of metal X.

The frequency f ₀ is chosen such that the skin depth of each of the three coins is below the depth of any coating of the coin, but not to the depth of the coin's central plane P. For the first coin, the "skin depth" is δ
It is indicated by ₁ . However, for the second coin, the skin depth δ ₂ is greater than δ ₁ . This is because the magnetic field can penetrate the metal Y more easily than the metal X. For this reason, the skin depth δ ₃ is the smallest for the third coin.

It should be appreciated that there are three different peak attenuation levels in the LF processing circuit for the three types of coins shown in FIG. "Averaging" if you are going to use a frequency low enough that the magnetic field will be transmitted to a sufficient degree through all parts of the coin.
Due to the effect, it is impossible to clearly distinguish the first and second coins. On the other hand, the "skin effect" distinguishes between the second and third coins when trying to make the frequency very high so as to prevent the magnetic field from penetrating well below the thickness of the coin coating. That would be impossible. However, by properly selecting the LF idling frequency within a certain range, several different coin materials can be more reliably distinguished.

The LF sensor does not necessarily have to consist of two sensing coils. For example, there may be only one sensing coil, in which case the LF test has the advantage of being largely independent of coin thickness. On the other hand, there is no correction for changes in the coin movement path.

Finally, while the advantage resulting from using the particular frequency range mentioned above for the LF sensor entails using an inductive sensing device,
As long as the out-of-balance sensor is adopted instead of the inductive sensor, there are advantages of correction for coin movement path change and power-up when the coin arrives.
It should be emphasized that a capacitive sensor may be used.

Various modifications can be made to the coin validator described above. For example, the LF sensor may be a one-sided coil that responds primarily to coin material. By properly choosing the geometry of the validator's moving deck, any similar effects when moving coins along the coin track past the LF sensor are minimized.

In the case of certain circuit arrangements for the HF1 oscillator, the power consumption is negligible, in which case a non-switched power supply is required for the HF1 oscillator. Instead, the HF1 oscillator 300 is powered by the positive terminal of the power supply 304 and is continuous from this power supply, as shown in FIG. 13 (where the same reference numerals used in FIG. A current is drawn to the ground through the resistance element 306.

Another modification has been made to the circuit of FIG. In the embodiment of FIG. 3, the power consumption of the LSI is small and negligible, but the LSI is constantly energized. However, in the same situation, it is desirable to further reduce overall power consumption, which can be achieved by the switched supply arrangement employed in the circuit of FIG.

As shown, branch connection 1005
From the supply line 400 to the decompressor 1000, and the output of this decompressor is connected to the LS via line 1006.
It is connected to the I316 power supply input. A normally open electronic switch 1001 is connected in parallel with the decompression device 1000. The switch 1001 has a control input section, which is connected to the line 317 and receives the power-up signal generated by the LSI to close the switch.

The decompression device 1000 is the simplest decompression device and includes a high impedance resistance element. Before the coin arrives, the switch 1001 is open, and a part of the positive potential of the power supply 304 (determined by the high internal resistance of the LSI) is applied to the LSI. The electric power thus supplied to the LSI is sufficient to detect the arrival of a coin.

When a power-up signal is generated on the line 317 after the coin arrives, the electronic switch 1001 is closed,
The decompression device 1000 is effectively short circuited and thus the power supply 30
The positive potential of 4 is directly applied to the supply input section of the LSI 316, and L
SI will operate at full power to perform coin validity testing.

The dynamic current consumption of a CMOS LSI is proportional to the square of the voltage drop across it, so the total power consumed by the LSI is significantly reduced except when a power-up signal is present on line 317. Please note that it is done.

The voltage applied to the LSI before the coin arrives needs to be sufficiently higher than the minimum voltage required for the LSI to correctly execute the program, but from the viewpoint of minimizing the power consumption in the LSI. You have to choose. Furthermore, depending on the specific circuit provided in the combination device (for example, a vending machine or public telephone) to which the validator is to be connected, the LSI is required to correctly send the output logic signal to this specific circuit. A minimum supply voltage is required. The value of R _VR is carefully chosen so that the above criteria can be met simultaneously. However, the internal resistance of an LSI can change depending on its operating state, which will change the voltage approved for the LSI too much. To prevent such voltage fluctuations,
The pressure reducer 1000 is in the form of a voltage divider, as shown in FIG. 14, and includes a resistive element 1000 including 1003 and a unity gain amplifier 1004. The input of this amplifier is connected to the tapping point of the voltage divider and the output is connected to the supply input of the LSI. In this way, the supply voltage to the LSI is such that the resistance value of the resistive element 1003 does not _depend on any changes in the R _LSI .
2,1003 is kept equal to the same part of the supply voltage as far as the total series resistance.

In the embodiment described above, the signal from sensor HF1 is used to determine if the coin is passing, but the power up of various circuit blocks (ie 0 or low power to full power). Up to working power) HF is a disturbance indicating coin arrival regardless of whether the signal is appropriate for the allowed coins HF
Achieved in response to only occurring in one signal. Therefore, this inspection device can perform an automatic power-up function in response to at least most of the coins used in countries all over the world without electrical or mechanical modification, and it can be used in different countries. When adopting in P
It is only necessary to store the limit value in the ROM.

Further, the arrival of all the articles which may be genuine coins is detected, and only the article which has passed the first test is discriminated as a passing coin or a failing coin. Therefore, it is possible to utilize a signal that allows the number of unacceptable coins and the number of acceptable coins to be monitored, without adding components other than those required for the coin inspection function. This can serve as a guide to assess whether a particular device is experiencing an abnormal number of slags, is accepting bogus coins, or is not functioning properly.

[Brief description of drawings]

FIG. 1 is a schematic side view of a coin validator showing the placement of three inductive sensors, especially along the coin track.

2 is a cross-sectional view taken along the line 1a-1a in FIG.

FIG. 3 is a simplified block diagram of a decision control circuit used in connection with an inductive sensor.

FIG. 4A is a detailed circuit diagram 1 of this circuit.

FIG. 4B is a detailed circuit diagram 2 of this circuit.

FIG. 5 is a simple circuit diagram of a rectifying / smoothing circuit included in the circuits of FIGS. 3 and 4A.

FIG. 6 is a diagram of a signal diagram for explaining the operation of this rectifying / smoothing circuit.

FIG. 7 is another signal diagram showing the operation mode of the analog-digital converter supplied with the output signal from the rectifying / smoothing circuit.

FIG. 8A is one of a flowchart showing how a large scale integrated circuit (LSI) included in the circuits of FIGS. 3, 4A and 4B may be programmed.

8B is a second flowchart showing how a large scale integrated circuit (LSI) included in the circuits of FIGS. 3, 4A and 4B may be programmed.

FIG. 9 is a diagram of a waveform diagram showing the times at which power is supplied to different parts of the decision control circuit.

FIG. 10 is a diagram showing various signal waveforms for explaining the significance of powering up the high frequency oscillator in the determination control circuit.

FIG. 11 is a diagram showing how a first inductive sensor connects to an oscillator circuit.

FIG. 12 shows various “skin depths” in three coins of the same diameter, thickness and diametrical cross section, each coin being exposed to an oscillating electromagnetic field of only one particular frequency from both sides. And (c) is a metal core wrapped with different metals, (a) is a metal core wrapped with different metals, (b) is a coin with two kinds of metals reversed, and (c) ) It is a figure showing what consists of only one metal.

FIG. 13 shows a modified decision control circuit, FIG.
FIG. 7 is a simplified block diagram similar to FIG.

FIG. 14 is a diagram of a circuit diagram showing a preferred method of implementing a portion of the circuit of FIG.

[Explanation of symbols]

 4, 5, 6 coin path forming device HF1, LF, HF2 inductive device 316, 315 circuit device

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Hutchinson, Derek United Kingdom. Middlesex, Hillington, Myrtle Close 7

Claims (15)

[Claims] 1. A coin validity checking device which requires electric power for a coin checking operation, and interacts with a device (4, 5, 6) forming a coin path and coins on the coin path. A device consisting of a plurality of inductive devices (HF1, LF, HF2) which generate information signals by means of one of the inductive interaction devices (HF1) which generate information signals in response to most coins, A circuit device (3) for determining whether the information signal indicates an allowed coin.
16, 315), actuated when an information signal is generated from one of the inductive interaction devices to initiate the supply of power to another of the inductive interaction devices to enable coin inspection operation. A detection device (316), the detection device being operable regardless of whether the information signal from one of the inductive interaction devices indicates a passing coin, thereby providing the power supply. Is a device that wants to be executed virtually every time a coin passes along the coin path. 2. Device according to claim 1, wherein the circuit parts (30) are adapted to be individually powered up.
0, 301, 302, 315, 316) for powering up each of the circuit parts during a period requiring a coin inspection operation, and not for powering up in other periods. A device comprising. 3. The device according to claim 2, wherein one of the circuit portions (315) is a storage unit including a reference value combined with an allowable coin, and the control device (316) stores the storage unit. A device characterized by being powered up for a period of time requiring access to its contents and not being powered up during other periods. 4. The device according to claim 3, comprising a plurality of interaction devices (HF1, LF, HF2), one of the interaction devices (HF1) operating at a continuous power level. And a control device (316) adapted to power up the remaining interaction device in response to the generation of said information signal. 5. The apparatus according to claim 4, wherein the controller (316) for determining whether the information signal indicates an allowed coin has at least one of the information signals at a predetermined amplitude (1 / TH). Need to maintain in the above 1
Two information signals are adapted to reduce their amplitude in response to said one interaction device (HF1) interacting with the coin, the reduced amplitude of said one information signal being at said predetermined amplitude at low power. The device being smaller, the one interaction device being powered up such that the reduced amplitude of the one information signal remains above a predetermined amplitude. 6. A device according to any of claims 3 to 5, characterized in that it has a common coin path (4, 5, 6) for inserting all coins into the device. 7. The device according to claim 3, wherein the circuit device (16, 315) comprises a memory device (315) containing a reference value in combination with an allowed coin, the circuit device being the device. Is operable to determine whether the coin being tested is an acceptable coin by comparing the information signal with the reference value, and to the desired set of coins determined to be acceptable by the storage device. A device characterized in that it is programmed with any desired set of corresponding reference values. 8. The device according to claim 7, wherein the storage device is a programmable persistent fixed storage device. 9. The device according to claim 3, wherein at least one interaction device (HF1) is a pair of inductive or capacitive sensing devices (HF1M, HF1C).
And these sensing devices include coin paths (4,5,
6) They are mounted so as to face each other and to be separated from each other on the opposite side faces, and the coins moving along the coin path are arranged such that the coins substantially stay in a predetermined lateral positional relationship with the sensing device. And these sensing devices are connected to the circuit arrangement (315, 316), one of the sensing devices (HF1M) being one of the coins depending on the degree of interaction between the field and the coin. The sensing device (HF1C) on the other hand is a correction device that acts mainly to reduce the variation of the measurement value due to the change in the coin movement path. A device characterized in that the inductance or capacitance values are chosen to be different values to increase the ratio of measurement sensitivity to variation. 10. The device according to claim 9, wherein the sensing devices are inductances connected to each other in series, the measuring inductance having a larger inductance value. 11. The device according to claim 10, wherein the sensing devices are inductances connected in parallel with each other, the measuring inductance having a small value. 12. The device according to claim 3, wherein at least one of the interaction devices (L
F) is an inductive sensor arranged to give an oscillating electromagnetic field to the coin in the inspection area, and the circuit device (316,
315) is arranged to determine whether the degree of interaction between the field and the coin is indicative of an allowed coin, such that the field pierces the coin in a direction substantially perpendicular to the plane of the coin. The frequency of the oscillating field is such that the skin depth of the field in the coin is below the depth of the surface coating in the presence of a permissible coin with a surface coating, but does not reach the center plane of the coin. A device characterized by being selected. 13. The device according to claim 12, wherein the frequency is 80 to 200 KHz. 14. The apparatus according to claim 13, wherein said frequency is approximately 120 KHz. 15. The device according to claim 3, wherein at least one of said information signals is generated in the form of an oscillating signal and exchanged for a DC signal, this conversion being effected by a rectifying circuit (313). This rectification circuit is operated by the first and second networks (445, 446) and these two circuits.
A device (440, 441) for alternately providing positive and negative half cycles of the oscillation signal to one network, a smoothing device for exchanging each half-wave signal into a DC signal in each network, and a DC signal from the two networks. A device (44) for generating an output signal which in combination has a magnitude equal to the sum of the coefficients of the two DC signals.
7) A device comprising: