JPH01250189A - Liquid sensing device and vendor burglarproof device using this device - Google Patents

Abstract

PURPOSE:To sense only a liquid having a high conductivity by connecting the output terminal of a reference voltage oscillating circuit to one of a pair of electrodes and connecting the input terminal of a voltage comparing circuit, which outputs the output for an input voltage having a certain value or higher, to the other. CONSTITUTION:The output terminal of a reference voltage oscillating circuit 11 is connected to one of a pair of electrodes 9a and 9b provided in the passage of liquid charged from a supply entrance 2, and the input terminal of a voltage comparing circuit 12 which outputs the output for the input voltage having a certain value or higher is connected to the other electrode. When liquid comes into contact with the pair of electrodes 9a and 9b, the voltage inputted to the voltage comparing circuit 12 is raised or reduced because of the difference of conductivity. Thus, only liquid having a certain conductivity or higher is sensed. The operating circuit of a coin mechanism is turned off by the output from the voltage comparing circuit to prevent the change from being stolen.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application in Industry-1-] The present invention relates to a liquid sensing device for a liquid exhibiting conductive properties, and particularly to a theft prevention device for a vending machine using the device.

[Conventional Technical Field] Conventionally, in a vending machine, a shooter is provided following coin insertion [-1, and at the exit of this shooter =
A part of the hopper of the change refund mechanism, called a 1-inch mechanism, is open.

[Problem to be solved by the invention'XU] However, recently, there have been a number of cases where people have had their change stolen by having neutral detergent poured into them when they inserted coins. This is because the neutral detergent injected from the inlet flows down the chute and enters the coin mechanism from the hopper, permeates into the operating circuit and short-circuits the circuit due to its conductive nature. be.

There have also been cases of pranks where liquids such as soy sauce or sauces, which have higher conductivity than neutral detergent, are injected through the inlet.
These problems not only cause short circuits but also corrode the inside of the machine.

On the other hand, if the liquid injected from the inlet is mourning water such as rainwater or tap water, for example, even if it enters the coin mechanism, its water permeability prevents it from entering the circuit. Therefore, no problem will occur.

The object of the present invention is to provide a liquid sensing device that can detect only liquids that exhibit high conductivity, such as neutral detergent, soy sauce, and sauce, out of the liquids that are inserted through the insertion of a coin. Vending machine theft prevention IE'
I am trying to provide A location.

[Means for Solving the Problems] In order to achieve the above-mentioned technical problems, the present invention provides an output terminal of a reference voltage oscillation circuit to one of a pair of electrodes provided in a passage of liquid injected from the input ``1''. One electrode is connected to the other electrode, and the input end side of a voltage comparator circuit that outputs an output voltage less than a certain input voltage is connected to the other electrode.

In this case, it is effective to use alternating current on the reference voltage oscillation circuit side for reasons described later.

Then, a liquid sensing device configured as described above is installed in a vending machine, and an alarm device such as a coin mechanism or a buzzer is connected to the output end of the voltage comparison circuit. It is a combination of 1i and 11 ways for operation of y Yoshito light and sub-operation.

[Function] When a liquid comes into contact between a pair of electrodes, the difference in electrical conductivity causes a difference in the voltage applied to the voltage comparison circuit, so only liquids that exhibit electrical conductivity above a certain level are sensed. You can't sense anything else.

At this time, if alternating current is applied to the reference voltage oscillation circuit side, the polarization phenomenon does not occur in the electrodes as in the case of direct current, so the sensitivity of the liquid to be sensed can be increased.

Additionally, by turning off the operating circuit of the coin mechanism using the output from the voltage comparison circuit, it is possible to prevent change from being stolen.
Moreover, by turning on the operating circuit of an alarm device, a warning light, etc., it is possible to notify the user of the occurrence of an abnormality and prevent the change from being stolen.

[Embodiment] The drawings show an embodiment of the present invention, and a case in which the present invention is applied to a theft prevention device for a vending machine will be explained in detail below. Machine!
The front door 1a is provided with, for example, a coin slot 2, and below that, a change payout port 3 and a product takeout port 4 are provided. Following the input port 2, a chute 5 is provided tilting in one direction, as shown in FIG. It is being Therefore, non-viscous water is drained in the direction F from this drain port 2a. Additionally, a funnel-shaped member 6 is opened at the outlet of the shooter 5.
is a hopper leading to a coin mechanism such as a coin discrimination mechanism and a change refund mechanism. still.

The coin slot may be a bill slot or a currency exchange slot.

A liquid guide path 7 is provided on the lower side of the shooter 5, and a sensor portion 8 is provided on the F side of the liquid guide path 7, facing a small hole 7a provided in the path. installed. This sensor part 8 has an open case-like structure, and has a pair of electrodes 9a made of stainless steel, for example.
, 9b are arranged side by side, and the conducting wire led out from this sensor part 8 is connected to a box 10 attached to the back side of the first door 1a, and a circuit described later is housed in the box. There is.

Fig. 3 is a circuit block diagram of the device of the present invention, and Fig. 4 is a circuit block diagram of the device of the present invention! It is an integrated circuit diagram. FIG. 1111 shows a reference voltage oscillation circuit, which is composed of an astable multivibrator using an operational amplifier (hereinafter referred to as "op-amp") OAl. R2 to R1 and C1 are operational amplifiers O^1
These resistors and capacitors are connected to the astable multivibrator to form an astable multivibrator, and by changing the resistance value and capacitance value of these, the frequency and pulse width of the oscillation output pulse of the astable multivibrator can be adjusted. The oscillation output pulse has a frequency of 111 in this embodiment.
11L, duty ratio is 50%, amplitude is +2Vp-
It is p. , a yielding oscillation output pulse is delivered to sensor portion 8 via resistors R5 and C2.

The sensor part 8 is for detecting conductive dust in the liquid, and is E
As mentioned above, for example, a pair of stainless steel electrodes 9a,
9b, one electrode 9a is connected to the output terminal of the oscillation circuit 11, and the other electrode 9b is grounded via a resistor R6. Therefore, this resistor R6 is connected to the sensor part 8.
A pulse current flows in response to the conductive dust in the liquid that has entered the chamber. That is, when no liquid enters the sensor portion 8 and the resistance between the pair of electrodes 98.9b is infinite, no pulse current flows through the resistor R6. but,
When liquid enters the sensor part 8 and the resistance between the pair of electrodes of the sensor part 8 becomes small, a pulse current flows through the sensor part 8 to the resistor R6 due to the oscillation output pulse of the oscillation circuit 11. The magnitude of the pulse current increases as the amount of conductive dust in the liquid increases. Therefore, conductive dust in the liquid can be detected by detecting the pulse current flowing through the resistor R6.

Reference numeral 12 denotes a voltage comparison circuit which smoothes the pulsed terminal voltage of the resistor R6 into a DC voltage and compares it with a reference voltage. R7, R8, D, and C3 are resistors, diodes, and capacitors that constitute a 9F smoothing circuit (or peak detection circuit) for smoothing (or peak detection) the terminal voltage of the resistor R6. OA2 is an operational amplifier that serves as a comparator, and receives the output of the f-slip circuit (or peak detection circuit) at its non-inverting input terminal via a resistor R9. RIG and VR are a resistor and a variable resistor for generating a reference voltage, and the reference voltage can be changed by adjusting the value of the variable resistor VR. This reference voltage is applied to the inverting input terminal of operational amplifier 0^2. C4 is a capacitor for noise cancellation. The operational amplifier OA2 generates an output signal when the voltage input to its non-inverting input terminal is higher than the reference voltage. R11, RI2, and C5 are a resistor and a capacitor that constitute a circuit that absorbs noise entering the output side of the operational amplifier OA2.

When the voltage comparison circuit 12 adjusts the resistance value of the variable resistor VR as appropriate, when the conductive dust in the liquid detected by the sensor part 8 exceeds the permissible value.

It operates to output a signal, that is, an abnormality detection signal.

13 is a latch circuit composed of a thyristor CR;
When an abnormality detection signal is generated from the voltage comparison circuit 12, it plays a role of latching the abnormality detection signal. in particular,
The control terminal of the thyristor CR is connected to the output terminal of the voltage comparison circuit 12, and when an abnormality detection signal is output from the voltage comparison circuit 12, the thyristor CR becomes conductive and -H
An abnormality is detected when conduction occurs (Thyristor CR is activated even if R4 disappears.
The conductive state continues unless the supply of current to the terminal is stopped. Therefore, it performs a latching function.

14 is a relay circuit, which is connected in series to the thyristor CR via the reset switch RS.
It is activated when conduction occurs, and functions to, for example, sound a buzzer or cut off the operating circuit of a coin mechanism in a vending machine. Reset switch R3 is a latch circuit!
When thyristor CR constituting 3 becomes -l conducting state,
Since the conductive state continues even if the abnormality detection signal inputted to the control terminal disappears, the thyristor CR is provided so that the current flowing through the thyristor CR can be cut off and reset to the non-conductive state.

In this device, if the liquid does not enter the sensor part 8, or if the conductive dust in the liquid is within the permissible range even if the liquid does enter, the amplitude of the pulse current flowing through the resistor R6 due to the oscillation output pulse of the first oscillation circuit 11 is small. , the DC voltage obtained by smoothing the terminal voltage of resistor R6 is J, I, ? ? '! lower than the voltage. Therefore, no abnormality detection signal is generated from the operational amplifier 0^2 of the voltage comparison circuit 12. Therefore, the thyristor CR constituting the latch circuit 13 remains non-conductive, and the relay circuit 1
4 does not work.

However, if a liquid with conductivity exceeding the permissible range, such as neutral detergent, soy sauce, or sauce, enters the sensor part 8, the amplitude of the pulse current flowing through the resistor R6 increases due to the oscillation output pulse of the oscillation circuit 11, and the The DC voltage obtained by slipping the terminal voltage of the resistor R6 by tP exceeds the reference voltage. Then, a signal, ie, an abnormality detection signal, is output from the operational amplifier 0^2, and the thyristor CR is made conductive using this abnormality detection signal as a trigger. Then, relay R1 is activated,
An alarm is issued by a buzzer or the like, and the power to the coin mechanism operating circuit of the vending machine is turned off. this? When the service engineer learned of the occurrence of the abnormality from the IJ report, he immediately turned off the reset switch. ? In addition to halting the reporting, appropriate measures will be taken in response to abnormal occurrences.

[Effects] Since the present invention is configured as described below, it can produce the following effects.

In the apparatus according to claim 1.

This makes it possible to sense liquids that exhibit conductivity within a certain range.

Claim 2, t! For the equipment listed above,
It is possible to increase the sensitivity of the position.

When the device according to claim 3 is configured to operate with a neutral detergent, it can also detect soy sauce, sauce, etc., which have lower conductivity than that, and by injecting these liquids, This can prevent change from being stolen from a vending machine or the internal mechanism from being damaged.

[Brief explanation of the drawing]

Fig. 1 is a front view of an r1 vending machine embodying the present invention, Fig. 2 is a sectional view showing the main parts of the invention, Fig. 3 is a block diagram showing the main parts of the invention, and Fig. 4 is a circuit. It is a diagram. l...Vending machine 2...Inlet 5...Shooter 6...Hopper 7...Liquid guide path 8...Sensor part 9a, 9
b... Electrode 11... Reference voltage transmitting circuit 12... Voltage comparison circuit 13... Latch circuit 14... Relay circuit

Claims (1)

[Claims] 1. The output end side of the reference voltage oscillation circuit is connected to one of a pair of electrodes provided in the path of the liquid injected from the inlet, and the output end side of the reference voltage oscillation circuit is outputted to the other electrode at an input voltage of a certain value or higher. A liquid sensing device characterized in that the input ends of a voltage comparator circuit are connected to each other. 2. The liquid sensing device according to claim 1, wherein an alternating current is applied to the reference voltage oscillation circuit side. 3. The liquid sensing device according to claims 1 and 2 is installed in a vending machine, and an alarm device such as a coin mechanism or a buzzer, or a warning light, etc. is installed on the output end side of the voltage comparison circuit. A theft prevention device characterized by having an operating circuit connected.