JPS5839291B2 - detection circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a detection circuit using a heat-sensitive cylisk, and more particularly to a detection circuit that has functions such as detecting the temperature of hot water in a bathtub, detecting the water level, and monitoring the same.

Products that use thermistors, bimetals, etc. have been commercially available to detect bath water temperature.

However, since the thermistor only has the function of detecting temperature, it is necessary to use a switching element such as a transistor in order to detect the temperature and activate the alarm.

In addition, since bimetallic devices use mechanical contacts to open and close, there is a problem with the lifespan of the contacts in high-humidity locations such as bathrooms.

Furthermore, if a function was to be added such as detecting the water level when water is being supplied to the bathtub or monitoring the water level to prevent emptying, a large number of elements such as transistors would be required.

This invention was made in view of the above points, and by utilizing the heat-sensitive function and switching function of the heat-sensitive Cyrisk, it can be configured with an extremely small number of active elements, and can be used to detect water temperature, water level, etc. in bathtubs, etc. The purpose of this invention is to provide a detection circuit that also has functions such as monitoring.

A heat-sensitive SIRISK is an element that has both a temperature detection function and a switching function that changes from a non-conducting (off) state to a conducting state (on) when the ambient temperature exceeds a predetermined temperature. As shown in FIG. 2, an N-type base layer 2. A P-type base layer 3 and an N-type cathode region 4 are sequentially formed, and are provided with an anode terminal A, an N-gate terminal GN, a P-gate terminal GP, and a cathode terminal K, respectively.

FIG. 2 is a circuit diagram showing an embodiment of the present invention using a heat-sensitive thyrisk.
There are two methods, one using the P gate terminal GP and the other using the P gate terminal GP, and this embodiment is a method using the N gate terminal GN.

In the figure, R1 is a resistor that limits the current flowing through the heat-sensitive thyristor T8, and R2 is a variable resistor connected between the N gate terminal GN and the positive electrode of the power source E. By adjusting this variable resistor R2, the heat-sensitive thyristor Ts This is to adjust the switching temperature.

R3 is a resistor connected between the N gate terminal and the cathode terminal.

SL is a power switch, S2 is a changeover switch, the changeover contact A is for checking the power battery, the port is for water level detection, and the contact C is for hot water temperature detection and prevention of dry boiling.

R6 is a resistor connected between the switching contact a and the cathode terminal of the thermal thyristor Ts, a is the electrode connected to the switching contact port, and C is a common electrode connected to the cathode terminal K of the thermal thyristor Ts. Electrodes a and c are arranged so that when the water level reaches a predetermined position, they are immersed in water to create electrical continuity.

TRI is an NPN transistor whose collector is connected to the switching contact c and whose emitter is connected to the cathode terminal K of the heat-sensitive thyristor Ts, b is the water level detection electrode for preventing dry heating, and R4 and R5 are between the positive terminal of the power source E and the electrode terminal. This is a resistor that divides the voltage and supplies it to the base of the transistor TRI.

Electrode C is placed in parallel with common electrode C, and when there is sufficient water in the bathtub, both electrodes S and C are immersed in water to be electrically conductive, and when water leaks and the water level drops, both electrodes C and C are connected. , c becomes non-conductive.

Therefore, the electrodes a, b, and c are arranged such that the common electrode C is the lowest electrode and the electrode a is the lowest electrode.
, b are usually placed at the same level or slightly higher than electrode a in the bathtub.

Note that X is an output terminal.

The values of the resistors R1 to R6 are determined under the following conditions.

Even when the heat-sensitive thyristor Ts conducts, the resistor R1 suppresses the current to a level slightly larger than its holding current, thereby ensuring turn-off of the heat-sensitive thyristor.

The resistor R2 is set so that when the changeover switch S2 is switched to the contact port when there is no water in the bathtub and electrodes a, b, and c are open, the heat-sensitive thyristor Ts is turned off.

Set the value of R3.

On the other hand, when the electrodes S and C are immersed in water, the transistor T
□1 selects the values of resistors R4 and R5 so that they are non-conductive.

The resistance value of the resistor R5 may be zero.

The value of the resistor R6 is that when the changeover switch S2 is switched to contact I, the thermal thyristor TS becomes conductive when the voltage of the power source E is above the specified value, and the thermal thyristor TS becomes conductive when the voltage of the power source E drops below the allowable value. Set to be non-conductive.

I believe that the operation of this circuit can be easily understood from the above explanation of the configuration, but I will briefly explain it here.

First, when the power switch S1 is turned on, this circuit enters the operating state.

When the changeover switch S2 is switched to contact A, the power supply battery is inspected, and if the power supply battery voltage exceeds the specified value, the heat-sensitive thyristor T8 conducts and the voltage at the output terminal X drops to its ON voltage and becomes extremely low. .

However, the voltage of the power supply battery decreased and the heat-sensitive thyristor Ts
When the breakover voltage is no longer reached, it is no longer conductive and the battery voltage X appears at the output terminal X.

This allows inspection of the power supply battery.

Next, when the changeover switch S2 is switched to the contact port, a water level detection operation is performed when water is supplied to the bathtub.

That is, while water is not immersing between electrodes a and C, both electrodes a
, c are open, so the heat-sensitive thyristor Ts is in a non-conducting state and the power supply voltage appears at the output terminal X.

As the water supply progresses and immerses between the electrodes a and c, the heat-sensitive thyristor Ts becomes conductive, and the potential of the output terminal X decreases.

Therefore, it is more convenient to use the voltage between the positive terminal of the power source E and the output terminal X when attempting to issue a signal indicating the completion of water supply.

Furthermore, when the changeover switch S2 is switched to contact C, the water temperature is detected and water boiling prevention is performed.

That is, since water is normally immersed between the electrodes A and C, the transistor TR□ is non-conductive.

Therefore, at the beginning of heating, the heat-sensitive thyristor Ts is in a non-conducting state, and the power supply voltage appears at the output terminal X.

As the temperature of the hot water rises, the temperature of the heat-sensitive thyristor T8 also rises, and when it reaches its switching temperature, it becomes conductive and the potential of the output terminal X decreases.

This makes it possible to detect the hot water temperature, and the switching temperature can be set arbitrarily by adjusting the resistor R2.

By the way, if the water level in the bathtub drops due to a water leak, the bathtub will become empty and there is a risk of fire.

In this circuit, when the water level in the bathtub decreases and the circuit between electrodes S and C is opened, the transistor TR1 becomes conductive, and the heat-sensitive silicon risk Ts becomes conductive regardless of the temperature, lowering the potential of the output terminal X and issuing an alarm. .

In the above description, it has been stated that detection can be performed based on the level of the potential of the output terminal

Furthermore, if the electric current of the heat-sensitive cyrisk can be used, it is most efficient to insert an alarm generating device directly into this circuit.

In the above embodiment, low and high potentials can be obtained at the output terminal X depending on whether the heat-sensitive thyristor T8 is turned on or off. If BjM is output from the cathode side, an output having the opposite phase to the above can be produced.

Further, in the above embodiment, the transistor TRI constituting the dry firing prevention circuit was connected between the gate terminal GN and the cathode terminal of the heat-sensitive thyristor Ts, but it was connected in parallel between the gate terminal GN and the anode terminal A. Even if they are connected, it is easy to configure them to have similar functions.

FIG. 3 is a circuit diagram showing another embodiment of the present invention, in which the P gate terminal GP of the heat-sensitive thyristor Ts is used.

In the example circuit shown in Fig. 2, the wiring arrangement of the circuit components is swapped between the anode terminal A and the cathode terminal of the heat-sensitive thyristor Ts, and the power supply E has the positive terminal on the anode terminal A side and the negative terminal on the cathode terminal side. A PNP l-transistor is used for the transistor T□1 due to the circuit configuration.

Therefore, the output terminal X outputs a high potential when the heat-sensitive silicon risk Ts is conductive, and outputs a low potential when it is not conductive.

The operation of this circuit can be easily understood from FIG.

In the embodiment shown in FIG. 3 as well, by inserting the resistor R1 into the anode terminal A side of the heat-sensitive thyristor and taking out the output terminal X from the anode terminal A side, it is also possible to obtain an output with the opposite phase.

Each of the above circuits operates not only on DC power but also on AC power, and can be applied to water heaters other than bathtubs.

As detailed above, this invention utilizes the heat-sensitive switching function of the heat-sensitive SIRISK and the switching function based on the gate potential of the normal SIRISK, so the device for preventing dry boiling by detecting the temperature of the water in the tank, detecting the water level, and monitoring it is extremely effective. This can be realized with a small number of elements and without using mechanical switching elements, and a highly reliable and long-life detection circuit device can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an example of a heat-sensitive cylisk used in the present invention, and FIGS. 2 and 3 are circuit diagrams showing one embodiment of the present invention. In the figure, Ts is a heat-sensitive silica, A is its anode terminal, K is its cathode terminal, GN, GP are its gate terminals, and E
is the power supply, R1 is the resistance of the anode circuit, R2゜R3 is the resistance of the gate circuit, a is the second electrode, b is the third electrode, C is the first
electrodes, TB□yTR2 are transistors, R5p R6
is the resistance of the base circuit, mouth is the first contact, C is the second contact, and S2 is the changeover switch. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A first and a second electrode that are electrically connected to each other through the stored water when the water stored in the tank reaches the predetermined water level, and when the water stored in the tank reaches the predetermined water level. a third electrode that maintains electrical continuity between the first electrode and the water reservoir, and is electrically disconnected from the first electrode when the water reservoir drops by an allowable water level from the predetermined water level; An n-gate (or p-gate) type heat-sensitive cyrisk is arranged so that the temperature of the stored water is transmitted and the temperature changes in accordance with the change in the temperature of the stored water.
A DC power supply with a positive terminal connected (or via a resistor) and a negative terminal connected to the cathode of the above heat-sensitive thyrisk via a resistor (or directly), and dividing this DC power supply voltage to keep the above heat-sensitive thyrisk non-conductive at room temperature. a resistive voltage divider for supplying a voltage to the gate of the heat-sensitive cyrisk to cause the heat-sensitive thyrisk to conduct when the temperature of the stored water reaches a desired value; a first contact connected to the second electrode; A connection line connecting the first electrode to the negative electrode (or positive electrode) of the DC power supply, and a connection line connecting the first electrode to the emitter of the transistor.
a second contact connected via a collector circuit;
a resistor circuit that applies a potential to the base of the transistor such that the transistor becomes non-conductive and conductive depending on conduction and non-conduction between the electrode of the transistor and the third electrode; A sensing circuit comprising a transfer switch for switching between the first and second contacts. 2. The detection circuit according to claim 1, wherein the switching temperature of the heat-sensitive thyrisk is adjusted by adjusting the voltage division ratio of a resistive voltage divider that supplies voltage to the gate of the heat-sensitive thyrisk.