JPH0823776B2 - Temperature control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application] The present invention relates to a temperature control device for controlling the temperature of an electric blanket, an electric carpet, an electric floor heater, or the like.

(Prior Art) Conventionally, for example, in a heating device such as an electric blanket, a blanket main body and a controller (temperature control device) are connected by a cable or the like, and a heater wire provided in the blanket main body by the temperature control device. In many cases, the calorific value is controlled to control the temperature of the blanket body.

FIG. 8 is a block diagram showing such an electric blanket and a temperature control device for controlling the temperature of the electric blanket.

The temperature control device shown in this figure has a sensor temperature detection circuit 1
A temperature setting circuit 2, a zero-cross signal generation circuit 3,
A sampling circuit 4, a comparison circuit 5, a drive circuit 9,
The thyristor 6 and the stop circuit 8 are provided, and the value of the temperature detection signal output from the temperature sensor 7a arranged in the electric blanket 7 is compared with the set temperature set in the temperature setting circuit 2. The temperature of the electric blanket 7 is controlled by controlling the amount of current flowing through the heater wire 7b arranged in the electric blanket 7 based on the comparison result.

The sensor temperature detection circuit 1 takes in a temperature detection signal output from a temperature sensor 7a provided in the electric blanket 7,
This is supplied to the comparison circuit 5 as the temperature detection signal S1.

Further, the temperature setting circuit 2 generates a temperature setting signal S2 having a value corresponding to a preset temperature setting value and supplies it to the sampling circuit 4.

In addition, the zero-cross signal generation circuit 3 includes the heater wire 7b.
It is configured to take in the AC voltage of the AC commercial power supply 10 that supplies power to and to detect the zero-cross point. When the zero-cross point is detected, a zero-cross signal S3 is generated and supplied to the sampling circuit 4. To do.

The sampling circuit 4 puts its output terminal voltage into a latch-up state when the zero-cross signal S3 is not supplied. When the zero-cross signal S3 is supplied, the temperature setting signal S2 output from the temperature setting circuit 2 is fetched and supplied to the comparison circuit 5.

The comparison circuit 5 compares the value of the temperature setting signal S2 output from the sampling circuit 4 with the value of the temperature detection signal S1 output from the sensor temperature detection circuit 1, and when S1> S2, that is, the above When the temperature of the electric blanket 7 is lower than the temperature set by the temperature setting circuit 2, a drive signal is generated and supplied to the drive circuit 9.

The drive circuit 9, when supplied with the drive signal, generates a trigger signal S4 and supplies it to the gate of the thyristor 6.

As a result, the thyristor 6 becomes conductive, and one end 10a of the AC commercial power supply 10 → heater wire 7b → the anode of the thyristor 6 and the cathode of the thyristor 6 → the other end of the AC commercial power supply 10
A current flows through the heater wire 7b along the path 10b, and the temperature of the electric blanket 7 rises.

When the reverse breakdown occurs in the thyristor 6, the stop circuit 8 detects the reverse breakdown and melts the thermal fuse 8c to stop the operation of the device.

(Problems to be Solved by the Invention) In the stop circuit 8 in such a conventional temperature control device, when the thyristor 6 causes a reverse breakdown, the diode 8a conducts and the resistor 8b receives a current. Since the thermal fuse 8c flows to generate heat, and the thermal fuse 8c is blown by the heat at that time, as shown in FIG. 9 (A), the AC commercial power source 10 outputs AC voltage, and FIG. When the thyristor 6 breaks down on the way as shown in FIG. 4), there is a problem that the amount of current flowing through the resistor 8b is too small and it takes too long before the thermal fuse 8c is blown.

In view of the above-mentioned circumstances, the present invention can immediately detect the breakdown of the thyristor when it breaks down and stop the operation of the device, thereby heating the load side caused by the reverse breakdown of the thyristor. An object of the present invention is to provide a temperature control device capable of preventing the above.

[Structure of Invention]

(Means for Solving Problems) In order to solve the above problems, a temperature control device according to the present invention provides a temperature detection signal output from a temperature sensor and a set temperature set in a temperature setting unit. A pulse generator that generates a synchronization pulse before the zero-cross point of the AC voltage applied to the thyristor is compared to a temperature control device that controls the heat generation amount of the heater by performing on / off control by the thyristor based on the comparison result. And a determination unit that determines whether or not this thyristor is causing reverse breakdown based on the reverse voltage of the thyristor when a synchronization pulse is output from this pulse generation unit, and the determination unit determines that the thyristor is When it is determined that a reverse breakdown has occurred, the circuit is configured with a stop unit that stops the circuit operation.

(Operation) In the temperature control device according to the present invention, in the above configuration, when the synchronizing pulse is output from the pulse generating section, the determining section determines whether or not the thyristor is in the reverse breakdown, and the thyristor is determined. When it is determined that the reverse breakdown has occurred, the stop unit stops the circuit operation.

(Embodiment) FIG. 1 is a block diagram showing an embodiment of a temperature control device according to the present invention.

The temperature control device shown in this figure has a sensor temperature detection circuit 11
A temperature setting circuit 12, a pulse signal generation circuit 13, a sampling circuit 14, a comparison circuit 15, a drive circuit 16, a thyristor 17, and a stop circuit 160.
Before the zero crossing point of the AC voltage applied in 7, while comparing the value of the temperature detection signal from the temperature sensor 19 arranged in the electric blanket 18 and the set temperature set in the temperature setting circuit 12 , A thyristor based on the result of this comparison
Determines 14 on / off. As a result, when the thyristor 17 is turned on, a current starts to flow at the zero cross point of the AC voltage. Further, before the zero cross point of the AC voltage, it is determined whether the thyristor 17 has a reverse breakdown. If the thyristor 17 has a reverse breakdown, the operation of the device is stopped.

The sensor temperature detection bottleneck 11 takes in the temperature detection signal output from the temperature sensor 19 provided in the electric blanket 18,
This is supplied to the comparison circuit 15 as the temperature detection signal S10.
In this case, if the temperature of the electric blanket 18 decreases, the value of the temperature detection signal S10 correspondingly increases.

Further, the temperature setting circuit 12 is provided with a setting device such as a variable resistor, generates a temperature setting signal S11 having a value corresponding to the temperature setting value set in the setting device, and outputs this to the sampling circuit 14. Supply.

In addition, the pulse signal generation circuit 13 is a resistor for current limiting.
21, a first pulse generator 22, a second pulse generator 23,
A zero-cross timing detection circuit 24 is provided to take in the AC voltage of an AC commercial power supply 25 for supplying electric power to the heater wire 20, and before and after the zero-cross point of this AC voltage, the first sync pulse signal S12 and the second sync signal. The pulse signals S13 are generated respectively.

As shown in FIG. 2, the first pulse generator 22 includes diodes 26a and 26b for limiting the voltage value and a first negative voltage detection circuit 27.
And a second negative voltage detection circuit 28 and a first gate circuit 37. The first synchronization pulse signal S12 is provided shortly before the AC voltage applied to the thyristor 17 changes from negative to positive. Is generated and is supplied to the sampling circuit 14.

The first negative voltage detection circuit 27 includes three transistors 29, 30, 31 that are turned on when a forward voltage larger than the value Vb1 is applied to the diodes 26a, 26b, and these transistors 29, 30, 31. It is provided with five resistors 32 to 36 that serve as current paths, and the polarity of the AC voltage output from the AC commercial power supply 25 becomes negative as shown in FIG. When a forward voltage larger than the value Vb1 is applied to 26a and 26b, a negative voltage detection signal S30 as shown in FIG. 3 (B) is generated and supplied to the first gate circuit 37.

Further, the second negative voltage detection circuit 28, like the first negative voltage detection circuit 27, has three transistors 38, 39 which are turned on when a forward voltage larger than the value Vb2 is applied to the diodes 26a, 26b. , 40 and each of these transistors 38,39,40
And the five resistors 41 to 45 serving as the current path of the AC voltage source, the polarity of the AC voltage output from the AC commercial power supply 25 becomes negative, and correspondingly, the diodes 26a and 26b have a value Vb2 from the value Vb2. When a large forward voltage is applied, FIG. 3 (C)
Generate a negative voltage detection signal S31 as shown in
Supply to the gate circuit 37. Note that here, the value Vb2 and the value V
b1 is set to be smaller than the forward conduction voltage 2VF of the diodes 26a and 26b connected in series. The value of the resistor 32 provided in the first negative voltage detection circuit 27 is
The value is set to be larger than the value of the resistor 41 provided in the second negative voltage detection food path 28, whereby | Vb2 |> | Vb1 |.

The first gate circuit 37 includes an inverter 46 that inverts the negative voltage detection signal S30, an output of the inverter 46, the negative voltage detection signal 31, and a zero-cross period signal S32 (see FIG. 3 (F)). An AND gate 47 for taking a logical product is provided, and the first sync pulse signal shown in FIG. 3 (G) is based on the negative electric negative pressure detection signal S30, the negative voltage detection signal S31, and the zero-cross period signal S32. Generate S12.

The second pulse generator 23 includes diodes 48a and 48b for voltage value control, a first positive voltage detection circuit 49, a second positive voltage detection circuit 50, and a second gate circuit 51. Shortly after the AC voltage applied to the thyristor 17 changes from negative to positive, the second synchronization pulse signal S13 is generated and supplied to the drive circuit 16.

The first positive voltage detection circuit 49 serves as two transistors 52 and 53 that are turned on when a forward voltage larger than the value Vb3 is applied to the diodes 48a and 48b, and current paths of these transistors 52 and 53. It is equipped with three resistors 54, 55 and 56, and the polarity of the AC voltage output from the AC commercial power supply 25 becomes positive as shown in FIG. When a forward voltage larger than the value Vb3 is applied to 48b, a positive voltage detection signal S33 as shown in FIG. 3D is generated and supplied to the second gate circuit 51.
In addition, the second positive voltage detection circuit 50 is the same as the first voltage detection circuit 49.
Similarly, two transistors 57 and 58 which are turned on when a forward voltage larger than the value Vb4 is applied to the diodes 48a and 48b, and three resistors 59 which are current paths of the respective transistors 57 and 58. , 60, 61, and the polarity of the AC voltage output from the AC commercial power supply 25 becomes positive,
Corresponding to this, when a forward voltage larger than the value Vb4 is applied to the diodes 26a and 26b, a positive voltage detection signal S34 as shown in FIG. 3 (E) is generated, which is generated by the second gate circuit 51. Supply to. Here, the value Vb4 and the value Vb3 are the forward conduction voltage 2VF of the diodes 48a, 48b connected in series.
Is set smaller than. Further, the value of the resistor 54 provided in the first positive voltage detection circuit 49 is set to be larger than the value of the resistor 59 provided in the second positive voltage detection circuit 51, whereby | Vb4 |> It is | Vb3 |.

The second gate circuit 51 includes an inverter 62 that inverts the positive voltage detection signal S33, and an AND gate 63 that takes the logical product of the output of the inverter 62, the positive voltage detection signal S34, and the zero-cross period signal S32. Therefore, the second synchronizing pulse signal S13 shown in FIG. 3 (H) is generated based on the positive voltage detecting signal S33, the positive voltage detecting signal S34, and the zero-cross period signal S32.

Further, the zero-cross period detection circuit 24 detects this when the power switch is turned on and detects the reset signal S3.
5, an initialization circuit 64 for generating 5, an inverter 65 for inverting the positive voltage detection signal S34, an OR gate 66 for ORing the output of the inverter 65 and the set signal S35, and the second negative voltage detection circuit 28. Takes in the output of the first voltage detection circuit 49 when the output of the negative voltage detection signal S31 is stopped,
It is provided with a D-type flip-flop 67 that latches this and then clears the latched result when the reset signal S36 is supplied from the OR gate 66. Then, every time the second negative voltage detection circuit 28 stops outputting the negative voltage detection signal S31, the output of the first positive voltage detection circuit 49 is taken in and latched, and this is shown in FIG. 3 (F). A zero-cross period signal S32 is generated, and this is generated by the first gate circuit 37,
And the second gate circuit 51.

Thus, in this pulse signal generation circuit 13, the first synchronization pulse signal S12 and the second synchronization pulse signal S13 are generated before and after the point where the AC voltage output from the AC commercial power supply 25 changes from negative to positive. Then, this is supplied to the sampling circuit 14 and the drive circuit 16, respectively.

The sampling circuit 14 uses the first sync pulse signal S12.
Inverter 69 that inverts the
A transistor 71 that turns on when a signal is output, a resistor 70 that limits the base current of this transistor 71,
Resistors 72, 73 for dividing the output of the transistor 71,
A transistor 74 that is turned on when the connection point voltage of these resistors 72 and 73 drops and a resistor 75 that limits the output current value of the temperature setting circuit 12 are provided, and the first synchronization pulse signal S12 is When not supplied, the output terminal voltage is held at the power supply voltage Vcc. In this state, when the first synchronization pulse signal S12 is supplied, the temperature setting signal S11 output from the temperature setting circuit 2 is fetched and supplied to the comparison circuit 15.

The comparison circuit 15 includes an output of the sampling circuit 14 and a temperature detection signal S1 output from the sensor temperature detection circuit 1.
It is provided with an operational amplifier 76 for comparing with the value of 0, and when the sampling circuit 14 holds the output terminal voltage at the power supply voltage Vcc, the output terminal thereof is set to the "Lo" level. Then, the temperature setting signal from the sampling circuit 14
When S11 is output, the value of the temperature setting signal S11 and the temperature detection signal S1 output from the sensor temperature detection circuit 1 are output.
Compared with the value of 0, when S10> S11, that is, when the temperature of the electric blanket 18 is lower than the temperature set by the temperature setting circuit 12, a heater-on signal S14 is generated and is sent to the drive circuit 16. Supply.

The circuit 16 is set when the heater-on signal S14 is supplied, and then the second sync pulse signal S13 is set.
The RS type flip-flop 80 that is reset when is supplied and the set output terminal of this RS type flip-flop 80 is charged when it is at "Lo" level and discharged when it becomes "Hi" level. A capacitor 82, a resistor 81 that determines the charging / discharging time constant of the capacitor 82, and a resistor 83 that converts a current discharged from the capacitor 82 into a voltage to generate a trigger signal S15. When the heater-on signal S14 is supplied, the trigger signal S15 is generated by the electric charge stored in the capacitor 82 and the thyristor 1
Conduct 7 After that, when the second synchronization pulse signal S13 is supplied, the generation of the trigger signal S15 is stopped and the capacitor 82 is caused to perform the charging operation.

The stop circuit 160 includes a voltage detection circuit 162, an AND gate 163, a drive circuit 165, a thyristor 166, and a resistor 167.
And a temperature fuse 168, and the thyristor 1
When 7 is in reverse breakdown, it detects this and stops the operation of the device.

As shown in FIG. 4, the voltage detection circuit 162 includes a transistor 180 which is turned on when the voltage between the anode and the cathode of the thyristor 17 exceeds a predetermined voltage in the reverse direction, and diodes 181a to 181d which protect the transistor 180. When,
It includes a transistor 182 which is turned on when the transistor 180 is turned on, and resistors 183, 184 and 185 which serve as current paths of these transistors 180 and 183, and the voltage between the anode and the cathode of the thyristor 17 becomes a predetermined voltage or more in the reverse direction. It is configured to generate a "Lo" voltage when it becomes low, and generate a "Hi" voltage otherwise, and supplies these voltages to the AND gate 163.

An AND gate 163 has an output of the voltage detection circuit 162,
It is configured to take a logical product with the output of the first pulse generator 22, and when the first synchronizing pulse signal S12 is output from the first pulse generator 22, the voltage detection circuit 162
If the "Hi" voltage is output from the thyristor 17
Generates a reverse breakdown detection signal S16 indicating that reverse breakdown has occurred and supplies it to the drive circuit 165.

The driving circuit 165 is set when the reverse break detection signal S16 is supplied, and thereafter, the second sync pulse signal is set.
The RS flip-flop 164 that is reset when S13 is supplied and the set output terminal of the RS flip-flop 164 are charged when the set output terminal is at “Lo” level,
a capacitor 169 that discharges when it reaches the i "level, a resistor 170 that determines the charge / discharge time constant of this capacitor 169,
The capacitor 169 is provided with a resistor 171 that generates a trigger signal S17 by converting the current discharged into a voltage, and when the reverse break detection signal S16 is supplied, the charge stored in the capacitor 169 is used. The trigger signal S17 is generated and supplied to the gate of the thyristor 166.
As a result, when a forward voltage is applied to the thyristor 166, the thyristor 166 becomes conductive and the resistor 167
Heat up. Then, the thermal fuse 168 is melted by the heat of the resistor 167, and all circuit operations are stopped.

Next, the operation of this embodiment will be described with reference to the waveform diagrams shown in FIGS.

First, as shown in FIG. 5 (A), the first pulse generation circuit 22 detects this shortly before the AC voltage output from the AC commercial power source 10 changes from negative to positive (for example, at time t1), and Four
As shown in FIG. 3B, the first synchronizing pulse signal S12 is generated to cause the sampling circuit 14 to select the output of the temperature setting circuit 12.

As a result, the temperature setting circuit 12 is connected to each input terminal of the operational amplifier 76 forming the comparison circuit 15 as shown in FIG.
And a temperature detection signal S10 from the sensor temperature detection circuit 11 are supplied.

Here, if the temperature of the electric blanket 18 is lower than the temperature set by the temperature setting circuit 12, and if S10> S11 correspondingly, the comparison is made as shown in FIG. 5 (E). The circuit 15 generates the heater-on signal S14 and causes the drive circuit 16 to output the trigger signal S15 as shown in FIG. 5 (F), which is supplied to the gate of the thyristor 17.

As a result, when a forward voltage is applied between the anode and cathode of the thyristor 17, the thyristor 17 becomes conductive as shown in FIG. 5 (G) and the forward voltage is applied to the thyristor 17. During this period, a drive current flows through the heater wire 20 as shown in FIG.

In addition, if a short time has passed after the AC voltage output from the AC commercial power supply 10 changed from negative to positive (for example, at time t
2), the second pulse generating circuit 23 detects this and generates the second synchronizing pulse signal S13 as shown in FIG. 5C,
This is supplied to the drive circuit 16.

As a result, the drive circuit 16 stops the generation of the trigger signal S15 and returns to the initial state.

Further, during this operation, when the thyristor 17 causes reverse breakdown as shown in FIG. 6 (B) and a reverse current flows through the heater wire 20 as shown in FIG. 6 (A), the voltage detection circuit 162 is detected. Detects this and outputs a "Hi" voltage as shown in FIG. 6 (C).

As a result, when the first pulse generator 22 outputs the first synchronizing pulse signal S12 as shown in FIG. 6 (D), the second pulse generator 23 or the second pulse generator 23 as shown in FIG. 6 (E) is output.
Until the synchronizing pulse signal S13 is output, the AND gate 163 generates the reverse break detection signal S16 as shown in FIG. 6 (F) and supplies it to the gate of the thyristor 166.

As a result, when a voltage is applied to the thyristor 166 in the forward direction, the thyristor 166 becomes conductive and a current flows through the resistor 167. Then, due to the heat generated by the resistor 167, the thermal fuse 168 is melted and the operation of the entire device is stopped.

As described above, in the present embodiment, it is detected whether or not the thyristor 17 is in the reverse breakdown just before the zero crossing point of the AC voltage applied to the thyristor 17, and when the reverse breakdown is detected. Since the thyristor 166 is turned on and the thermal fuse 168 is forcibly blown, even when the thyristor 17 breaks down midway, it is possible to detect this immediately and stop the device operation. it can. This causes an electric blanket due to the reverse breakdown of the thyristor 17.
18 can prevent overheating.

Further, in each of the above-described embodiments, the pulse signal generating circuit 13 is composed of discrete components, but as shown in FIG. 7, the voltage obtained by the AC commercial power supply 25 is divided by the resistors 140 and 141, and The comparison circuit 142 detects the polarity of the voltage division result, and the microcomputer 143 detects the zero-cross point of the AC voltage output from the AC commercial power supply 25 based on the detection result, and the first and second synchronization pulses. The signals S12 and S13 may be generated. In this case, these first and second synchronization pulse signals S are generated with the accuracy corresponding to the frequency of the crystal unit 144 that supplies the clock signal to the microcomputer.
It is possible to control the generation timing of 1, S13.

Further, in each of the embodiments described above, the trigger signal S15 is generated by the charging / discharging operation of the capacitor 82,
Even if a pulse transformer is provided instead of the capacitor 82, the same effects as those of the above-described embodiments can be obtained.

In each of the above-described embodiments, the thyristor 17 is used to energize the heater wire 20, but a bidirectional switching element such as a triac may be used instead of the thyristor 17. Also in this case, before and after the zero-cross point when the AC voltage output from the AC commercial power supply 25 changes from negative to positive and the zero-cross point when the AC voltage changes from positive to negative, the first and second synchronization pulse signals S1
By generating 2 and S13 respectively, the same effect as in the above-described respective embodiments can be obtained.

Further, in each of the above-described embodiments, the present invention has been described by taking the electric blanket 18 in which the heater wire 20 and the temperature sensor 19 are separated as an example. However, the heater wire and the temperature sensor such as a one-wire type wire Even when and are integrated, the reverse breakdown of the thyristor can be similarly detected to stop the circuit operation.

[Effect of the Invention] As described above, according to the present invention, when a breakdown occurs in the thyristor on the way, the thyristor can be immediately detected to stop the operation of the device, whereby the reverse breakdown of the thyristor can be performed. It is possible to prevent overheating on the load side due to

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a temperature control device according to the present invention, FIG. 2 is a circuit diagram showing a concrete example of the pulse signal generating circuit shown in FIG. 1, and FIG. 3 is this pulse signal generating circuit. FIG. 4 is a waveform diagram showing an operation example, FIG. 4 is a circuit diagram showing a concrete example of the voltage detection circuit shown in FIG. 1, FIG. 5 is a waveform diagram showing an operation example of this embodiment, and FIG. FIG. 7 is a waveform diagram showing an operation example, and FIG. 7 is a circuit diagram showing another example of the pulse signal generation circuit that can be used in the temperature control device according to the present invention.
FIG. 8 is a block diagram showing a conventional temperature control device, and FIG. 9 is a waveform diagram for explaining the operation of this temperature control device. 12 …… Temperature setting part (temperature setting circuit) 17 …… Thyristor, 19 …… Temperature sensor 22 …… Pulse generator (first pulse generator) 163 …… Judgment part (AND gate) 166 …… Stop part (thyristor) ) 168 ...... Thermal fuse

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroshi Ikeda 4-21, Yoshihara-cho, Nishi-ku, Nagoya-shi, Aichi Toshiba Audio-Video Engineering Co., Ltd. (56) Reference JP-A-59-99956 (JP, A) Actual Open Sho-60-25016 (JP, U) Actual Open Sho-61-51517 (JP, U)

Claims (1)

[Claims] 1. A temperature detection signal output from a temperature sensor is compared with a set temperature set in a temperature setting section,
In a temperature control device for controlling the heat generation amount of a heater by performing on / off control by a thyristor based on this comparison result, a pulse generator that generates a synchronization pulse before the zero cross point of the AC voltage applied to the thyristor, A determination unit that determines whether or not this thyristor is in reverse breakdown based on the reverse voltage of the thyristor when a synchronization pulse is output from the pulse generation unit, and this determination unit causes the thyristor to reverse breakdown. A temperature control device, comprising: a stop part that stops the circuit operation when it is determined that the power supply is down.