JPS6336001B2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention provides a latch relay for controlling the energization of a heating element installed in a heating device such as an electric carpet or a kotatsu, and a capacitor is connected in series to the latch relay. , a charging circuit is provided that charges the capacitor and turns on the latch relay with the charging current, and discharges the capacitor and turns on the latch relay with the discharge current.
A discharge circuit that is turned off is provided, a temperature setting means is provided for setting the temperature of the heating device, a temperature detecting means is provided for detecting the temperature of the heating device, and a set temperature consisting of the temperature setting device and the temperature detecting device is provided. A temperature comparison circuit is provided to compare the detected temperature, and the output from the temperature comparison circuit when the detected temperature is lower than the set temperature is used to control the charging circuit; The present invention relates to a temperature control device provided with a drive circuit that operates each of the discharge circuits according to the output when the output is higher.

<Prior art> Conventional temperature control devices include a latch relay that controls the supply of electricity to a heating element installed in a heating device such as an electric carpet or a kotatsu, and a capacitor is connected in series to the latch relay to charge the capacitor. At the same time, a charging circuit is provided that turns on the latch relay with the charging current, and a discharge circuit that discharges the capacitor and turns off the latch relay with the discharge current, and a volume controller as a temperature setting means for setting the temperature of the warming device. A temperature sensor (hereinafter described as a thermistor) is provided as a temperature detection means for detecting the temperature of the heating device, and a temperature comparison circuit is provided to compare the set temperature and the detected temperature consisting of the volume and the thermistor. , the charging circuit is operated by the output from the temperature comparison circuit when the detected temperature is lower than the set temperature, and the discharge circuit is operated by the output when the detected temperature is higher than the set temperature of the temperature comparison circuit. A drive circuit is provided to operate each of the two. The relay contact of the latch relay, the heating element, and the AC power source are connected in series to form the main circuit of the heating device.

Such a temperature control device uses a temperature comparison circuit to compare the set temperature set by the volume control and the detected temperature detected by the thermistor, and when the detected temperature is lower than the set temperature, the temperature control circuit compares the set temperature with the detected temperature detected by the thermistor. The drive circuit operated the charging circuit with the corresponding output, and the charging circuit charged the capacitor, and the charging current turned on the latch relay to energize the heating element. When the detected temperature is higher than the set temperature, the drive circuit operates a discharge circuit based on the corresponding output from the temperature comparison circuit, and the discharge circuit discharges the capacitor and generates a discharge current. The latch relay was turned off to cut off the power to the heating element.

<Problems to be Solved by the Invention> With the temperature control device as described above, the drive circuit starts the operation of the discharge circuit based on the output of the temperature comparison circuit when the detected temperature is higher than the set temperature. If the volume is operated in an attempt to raise the temperature of the heating device immediately after the capacitor's potential has not dropped sufficiently, the set temperature will become higher than the detected temperature due to the volume operation. As a result, the temperature comparator circuit outputs an output indicating the start of charging, and the drive circuit operates the charging circuit based on the output to charge the capacitor. However, since the capacitor is not sufficiently discharged by this charging current, the charging time is short, and moreover, the charging current is reduced by the volume control.
Therefore, the power applied to the latch relay becomes small and the latch relay is not moved and does not turn on. Therefore, even though the temperature comparison circuit outputs a signal to charge the capacitor and turn on the latch relay, the latch relay does not turn on.
It remains OFF. This causes the detected temperature to drop and become lower than the set temperature, and the temperature comparator circuit charges this capacitor and activates the latch relay.
An output indicating that the power is turned on is output, and the drive circuit causes the charging circuit to continue operating according to the output.
Since the capacitor has been fully charged, the latch relay does not turn on and remains OFF, resulting in a malfunction in which the heating element is not energized forever.

An object of the present invention is to provide a temperature control device that eliminates the above-mentioned drawbacks.

<Means for Solving the Problems> As shown in the drawings, the temperature control device of the present invention includes a latch relay that controls the energization of the heating element provided in the heating device, and a capacitor connected in series to the latch relay. , a charging circuit is provided that charges the capacitor and turns on the latch relay with the charging current, and discharges the capacitor 7 and turns on the latch relay with the discharge current.
A discharge circuit that is turned off is provided, a temperature setting means is provided for setting the temperature of the heating device, a temperature detecting means is provided for detecting the temperature of the heating device, and the temperature setting device, the temperature setting device, and the temperature detecting device are connected to each other. A temperature comparison circuit is provided to compare the set temperature and the detected temperature.
A drive circuit that operates the charging circuit using an output from the temperature comparison circuit when the detected temperature is lower than the set temperature, and operates the discharging circuit using the output when the detected temperature is higher than the set temperature. and a discharge sustaining circuit that maintains the discharge state of the capacitor due to the operation of the discharge circuit until the capacitor is sufficiently discharged, regardless of the output of the temperature comparison circuit.

<Function> The temperature control device configured as described above sets the temperature of the heating device with the temperature adjustment means, detects the temperature of the heating device with the temperature detection means, and compares the set temperature and the detected temperature with the temperature comparison circuit. When the output of the temperature comparison circuit is lower than the set temperature, the charging circuit is operated by the drive circuit, and the capacitor is charged by the operation of the charging circuit, and the latch relay is turned on with the charging current. Electrify the heating element. Furthermore, when the output of the temperature comparison circuit is higher than the set temperature, the discharge circuit is operated by the drive circuit, the discharge circuit discharges the capacitor, and this discharge current turns off the latch relay. to cut off the power to the heating element. After the capacitor starts discharging due to the operation of the discharging circuit, the discharging operation of the discharging circuit is continued by the discharge sustaining circuit until the capacitor is sufficiently discharged, and the latch relay is turned off by the discharging current of the capacitor. As a result, the capacitor will be charged from a sufficiently discharged state next time.

<Embodiment> An embodiment of the temperature control device of the present invention for controlling the temperature of a warming device such as an electric carpet or a kotatsu will be described with reference to the drawings.

In the drawing, 1 is an AC power supply, 2 is a heater, 3 is a latch relay (3A is a latch relay contact, 3B is a latch relay coil), 4 is an npn transistor,
5 and 6 are resistors, 7 is a capacitor, 8 is an npn transistor, 9 and 10 are resistors, 11, 12, and 13 are diodes, 14 is a resistor, 15 is an npn transistor, 16, 17, and 18 are resistors, 19 is a capacitor, 20 is a diode, 21, 22, 23, 2
4 and 25 are resistors, 26 and 27 are pnp transistors, 28 are resistors, 29 are diodes, and 30 are npn
transistor, 31, 32, 33, 34 are resistors,
35 is a temperature setting volume, 36 is a resistor, 37,
38 is an npn transistor, 39 and 40 are resistors, 4
1 is a thermistor.

Additionally, +Vcc is the high side of the DC power supply, and GND is the low side of the DC power supply.

A heater 2 and a latch relay contact 3A are connected in series to the AC power source 1 to form a main circuit.
A series circuit of a latch relay coil 3B and a capacitor 7 is connected to a DC power source via a resistor 5 and a transistor 4, forming a charging circuit for the capacitor 7. A transistor 8 is connected via a resistor 6 to the connecting end of the resistor 5 and the latch relay coil 3B and to the low side (GND) of the DC power supply, forming a discharge circuit for the capacitor 7.

The base of the transistor 8 is connected to the connection end of the resistor 14 and diode 11 of a series circuit of a resistor 9, a diode 11, and a resistor 14 connected to a DC power source. The connecting end of the diode 11 and the resistor 9 is also connected to the collector of a transistor 15 via the diode 12, and the emitter of the transistor 15 is connected to the low side (GND) of the DC power supply. The collector of the transistor 15 is also connected to the high side (+Vcc) of the DC power supply via a diode 13 and a resistor 10. Further, the collector of the transistor 15 is connected to the base of a transistor 30 via a resistor 16, a capacitor 19, and a resistor 21, and a resistor 28 is connected between the base and emitter of the transistor 30, and the emitter is connected to the low side (GND) of the DC power supply. connected to capacitor 1
The connecting end of 9 and resistor 21 and the low side of the DC power supply (GND)
A diode 20 having opposite polarity is connected to the diodes 13 and 21 and the capacitor 19.
, resistors 21 and 28, and transistor 30 form a discharge sustaining circuit.

Note that the base of transistor 4 is transistor 26.
The connecting end is connected to the collector of resistor 17, 1
Connected to the low side (GND) of the DC power supply via 8,
The connecting ends of the resistors 17 and 18 are connected to the base of the transistor 15. and transistor 2
The emitter of transistor 27 is short-circuited to the emitter of transistor 27, and the emitter is connected to the high side (+Vcc) of the DC power supply via resistor 23, and resistors 22 and 24 are connected between the collector of transistor 27 and the high side (+Vcc) of the DC power supply. are connected, and the connection ends of the resistors 22 and 24 are connected to the base of the transistor 26. Also, the collector of the transistor 27 and the resistor 24
The connection end of the diode 1 is connected to the low side (GND) of the DC power supply via the resistor 25.
1, 12, 29 and transistors 15, 26, 27
and resistors 17, 22, 23, and 24 form a drive circuit.

Also, resistors 33, 34, volume 35 and resistor 4
0, forming a resistance bridge with the thermistor 41,
The output terminals of the resistor bridge are connected to the bases of transistors 37 and 38, respectively, forming a differential amplifier. Transistors 37 and 38 of the above differential amplifier
The emitter of transistor 3 is short-circuited and connected to the low side (GND) of the DC power supply via resistor 39.
The collector of No. 8 is connected to the high side (+Vcc) of the DC power supply. The collector of the transistor 37 serves as the output terminal of the differential amplifier, and the output terminal is connected to the base of the transistor 27 via the resistor 31 and connected to the high side (+) of the DC power supply via the resistor 36.
Vcc), and the resistors 33, 34,
40, a volumetric volume 35, a thermistor 41, and transistors 37 and 38 form a temperature comparison circuit.

Note that the collector of the transistor 30 is connected to the base of the transistor 27. Further, a series circuit of a diode 29 and a resistor 32 is connected to provide feedback between the collector of the transistor 27 and the base of the transistor 37.

In the control device with the above configuration, first, the volume 35
When the temperature of the heating device is lower than the set temperature, the resistance value of the thermistor 41 is high, and the base potential of the transistor 38 is higher than the base potential of the transistor 37 as the output of the resistance bridge, the transistor 38 is turned on and the transistor 37 is turned on. is OFF. Then, the collector potential of the transistor 37 is ○ high, and the output of the differential amplifier is ○ high, so the transistor 27 is OFF. Therefore, since the transistor 26 is ON, the base current flows through the transistor 4 and the transistor 15, and the transistors 4 and 15 are in the ON state. When the transistor 15 is turned on, the base of the transistor 8 is short-circuited through the diode 12, so the transistor 8 is turned off. Therefore, the latch relay coil 3B causes the charging current of the capacitor 7 to pass through the resistor 5 for an instant to the transistor 4.
Flows when turned on. The latch relay 3 is then impressed by the instantaneous applied power and the latch relay contact is closed. Once the contact 3A is closed, its closure is latched (maintained) even if the capacitor 7 is saturated and charging current no longer flows. and,
The heater 2 is energized, and as the temperature of the heating device rises, the temperature of the thermistor 41 also rises and its resistance value decreases. Then, when the temperature decreases to a set value, the output of the resistor bridge is reversed, and the base potential of the transistor 38 becomes lower than the base potential of the transistor 37. Then, the transistors 37, 3 of the differential amplifier
The operation of the transistor 8 is also reversed, and the collector potential of the transistor 37 is ○low, that is, the output of the differential amplifier is ○low, so the base current of the transistor 27 flows and the transistor 27 is turned on, so that the transistor 26 is turned on.
It becomes OFF. Then, the base current does not flow through the transistors 4 and 15, and they are turned off.
Therefore, the transistor 8 has a resistor 9 and a diode 11.
Base current flows through transistor 8 and turns on.
do. Then, the charge in the capacitor 7 is instantly discharged via the latch relay coil 3B, the resistor 6, and the transistor 8. That is, since the reverse power is instantaneously applied to the latch relay coil 3B, the latch relay 3 is unlatched (held) and the contact 3
A is opened. (Contact 3A remains open until the next charging current flows). and heater 2
energization is stopped, the resistance value of the thermistor 41 increases, and the base potential of the transistor 38 also increases. However, when transistor 27 is turned on, transistor 3 is connected via diode 29 and resistor 32.
Since feedback is applied to the base of heater 2, energization of heater 2 will not start unless the temperature drops below the OFF state.

Even if the set value is changed immediately after the transistor 15 is turned off and the transistor 8 is turned on, the charging current of the capacitor 19 is transferred to the transistor through the resistor 10, the diode 13, the resistor 16, the capacitor 19, and the resistor 21. 3
It flows as a base current of 0, and the transistor 30 is turned on for a predetermined time. (This predetermined time is the charging time of the capacitor 19 until the capacitor 7 is discharged and the potential of the capacitor 7 becomes a low potential).
Since the transistor 30 allows the base current of the transistor 27 to flow, the transistor 27 remains on, and the transistor 26 remains off, so the transistor 4 does not turn on and charge the capacitor 7. This is maintained until the potential of the capacitor 7 becomes a low potential. When the potential of the capacitor 7 becomes low and the transistor 30 is turned off, the base current no longer flows through the transistor 27, the transistor 27 is turned off, and the transistor 26 is turned off.
ON, therefore, transistor 4 is also turned ON, capacitor 7 is charged, and instantaneous power is applied to latch relay coil 3B, and the contact is opened. And again, capacitor 19 is resistor 1 when transistor 8 is OFF and transistor 15 is ON.
6. Since the capacitor 19 is discharged through the transistor 15 and the diode 20, it is reset and waits for the next charge.

By the above-described operation, the temperature is kept constant, and even if the set value is varied at any time, stable operation is achieved without malfunction.

<Effects of the Invention> Since the temperature control device of the present invention has the above configuration, after the capacitor starts discharging, a signal indicating that the capacitor is to be charged is output from the temperature comparison circuit by operating the temperature setting means such as a volume control. Even if the capacitor is charged, the discharge circuit is operated by the discharge sustaining circuit regardless of the output of the temperature comparator circuit, and the discharge state is maintained until the capacitor is sufficiently discharged. ON
This eliminates malfunctions in which the latch relay remains OFF, that is, the heating element remains OFF indefinitely.

[Brief explanation of the drawing]

The figure is an electrical circuit diagram of an embodiment of a control device according to the present invention. 2: Heater, 3: Latch relay, 35: Temperature setting volume, 41: Thermistor.

Claims (1)

[Claims] 1. A latch relay is provided to control the energization of the heating element installed in the heating device, a capacitor is connected in series to the latch relay, the capacitor is charged, and the charging current is used to activate the latch relay.
A charging circuit is provided to turn on the capacitor, and a discharging circuit is provided to discharge the capacitor and turn off the latch relay using the discharge current. A temperature setting means is provided to set the temperature of the heating device, and a temperature to detect the temperature of the heating device is provided. A detection means is provided, and a temperature comparison circuit is provided for comparing the set temperature and the detected temperature formed by the temperature setting means and the temperature detection means, and an output from the temperature comparison circuit when the detected temperature is lower than the set temperature. Therefore, in a temperature control device provided with a drive circuit that operates the charging circuit and the discharging circuit respectively by the output from the temperature comparison circuit when the detected temperature is higher than the set temperature, A temperature control device comprising a discharge sustaining circuit that maintains the discharge state of the capacitor due to circuit operation until the capacitor is sufficiently discharged, regardless of the output of the temperature comparison circuit.