JP2522498B2 - 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 appliance such as an electric blanket, a blanket body and a controller (temperature control device) are connected by a cable or the like, and the temperature of the heating wire of a heater wire provided in the blanket body is controlled by the temperature control device. In many cases, the temperature of the blanket body is controlled by controlling the amount.

FIG. 3 is a block diagram showing a conventional electric blanket and a temperature control device for controlling the temperature of the electric blanket.

First, the electric blanket 1 will be described, and then the temperature control device will be described.

As shown in FIG. 3, the electric blanket 1 includes a blanket body 2 formed in a bag shape and a one-wire 3 arranged in the blanket body 2.

As shown in FIG. 4, the one-wire type wire 3 has a current passing function as well as a temperature detecting function of a core wire 4 formed in a linear shape and a heater wire spirally wound around the core thread 4. The ribbon-shaped sensor electrode 5 which has, the thermosensitive dielectric layer 6 formed so as to cover the sensor electrode 5 and the core thread 4, and the thermosensitive dielectric layer 6
The heater wire 7 is spirally wound around, and the insulating jacket 8 is formed so as to cover the heater wire 7 and the thermosensitive dielectric layer 6.

When a current is supplied to the heater wire 7, the heater wire 7 generates heat to raise the temperature of the blanket body 2. Also,
As the temperature of the heater wire 7 rises, the temperature of the heat-sensitive dielectric layer 6 changes, the dielectric constant changes, and the capacitance between the sensor electrode 5 and the heater wire 7 changes.

Next, the temperature control device will be described. The temperature control device is composed of the following parts.

That is, the sensor output capturing unit 10 that captures the output of the sensor electrode 5 corresponding to the temperature of the heater wire 7 and generates the first temperature detection signal S1 and the second temperature by converting the first temperature detection signal S1 into a predetermined level. A sensor temperature detection circuit 11 that generates a detection signal S2, a temperature setting circuit 12 that generates a temperature setting signal S3 corresponding to a preset temperature setting value, and an AC commercial power supply 21.
Zero-cross signal S4 by detecting the zero-cross point of the AC output of
And a sampling circuit 14 for sampling the temperature setting signal S3 at the time of supplying the zero cross signal S4, a value of the temperature setting signal S3 and a value of the second temperature detection signal S2. Comparing circuit 15
A drive circuit 16 for supplying the output of the comparison circuit 15 to the gate of a thyristor 17, which is a power control element, and a temperature fuse 23.
And a safety monitoring circuit 18 having a function of disconnecting the series circuit including the AC commercial power source 21 and the heater wire 7 when heating.

Then, the general operation of the temperature control device is the sensor electrode 5
The temperature detected by the temperature setting circuit 12 is compared with the set temperature set in the temperature setting circuit 12, and the amount of current flowing through the heater wire 7 is controlled based on the comparison result to control the temperature of the electric blanket 1. In addition, in the case of abnormal heating, the dielectric constant of the heat-sensitive dielectric layer 6 changes and the heat-sensitive dielectric layer 6 becomes conductive in an AC manner, and the current of the AC commercial power supply 21 causes the resistor 22 constituting the safety monitoring circuit 18. Abnormally overheats the resistor 22 through
Due to the abnormal overheating, the temperature fuse 23 is melted and the heater wire 7
It is to cut off the power supply to the equipment and ensure the safety in case of abnormal heating.

 Next, details of each component will be described.

The sensor output capturing section 10 includes a current-voltage converting resistor 19 inserted between one end of the sensor electrode 5 and the cathode of the thyristor 17, and a noise absorbing capacitor connected in parallel with the resistor 19. And 20 to generate a first temperature detection signal S1 having a value corresponding to the amount of charge flowing in and out of the sensor electrode 5 in response to the AC voltage applied to the heater wire 7, and supplying the first temperature detection signal S1 to the sensor temperature detection circuit 11. To do.

The sensor temperature detection circuit 11 takes in the first temperature detection signal S1 and rectifies it to generate a second temperature detection signal S2, which is supplied to the comparison circuit 15.

The temperature setting circuit 12 generates the temperature setting signal S3 described above,
Supply to the sampling circuit 14.

The zero-cross signal generation circuit 13 takes in the output of the AC commercial power supply 21 that supplies power to the heater wire 7, detects the zero-cross point thereof, generates a zero-cross signal S4, and supplies it to the sampling circuit 14.

The sampling circuit 14 holds the output terminal T at the voltage Vcc when the zero-cross signal S4 is not supplied. Then, when the zero-cross signal S4 is supplied,
The temperature setting signal S3 output from the temperature setting circuit 12 is fetched and supplied to the comparison circuit 15.

The comparison circuit 15 compares the value of the temperature setting signal S3 output from the sampling circuit 14 with the value of the second temperature detection signal S2 output from the sensor temperature detection circuit 11, and when S2> S3 (electrical When the temperature of the blanket 1 is lower than the temperature set by the temperature setting circuit 12, the drive signal S5 is generated and supplied to the drive circuit 16.

When the drive circuit 16 is supplied with the drive signal S5, the trigger signal
S6 is generated and supplied to the gate of thyristor 17. As a result, the thyristor 17 becomes conductive, and one end 21 of the AC commercial power supply 21
In the path of a → heater wire 7 → anode of thyristor 17, cathode of the thyristor 17 → the other end 21b of the AC commercial power supply 21, current flows through the heater wire 7 and the temperature of the electric blanket 1 rises.

 The above is the temperature control of the electric blanket 1.

On the other hand, the control for cutting off the supply of the AC commercial power supply 21 at the time of abnormal overheating is as follows.

That is, the safety monitoring circuit 18 includes a resistor 22 interposed between the sensor electrode 5 and the sensor output capturing section 10, and the resistor 22.
Is provided with a thermal fuse 23 for shutting off the circuit to prevent the AC commercial power source 21 from being applied to the heater wire 7 when the abnormal heat is generated.

When the heat-sensitive dielectric layer 6 melts due to some cause of heat generation and the heater wire 7 and the sensor electrode 5 come into contact (conduction), the AC commercial power supply 21a → the thermal fuse 23 → the heater wire 7
→ Conduction of the heat-sensitive dielectric layer 6 → Sensor electrode 5 → Resistor 22 → Resistor 19 → AC commercial power supply 21b causes the resistor 22 to generate heat due to the current flowing from the heater wire 7 to the sensor electrode 5 The power supply from the AC commercial power supply 21 to the heater wire 7 is cut off. In this way, even if the heater wire 7 and the sensor electrode 5 come into contact with each other through the melted thermosensitive dielectric layer 6, a large accident (for example, burning of an electric blanket) does not occur.

(Problems to be Solved by the Invention) However, as described above, the heater wire 7 and the sensor electrode 5 are
The resistor 22 is caused to generate heat by the current generated when the and are brought into contact with each other, and the thermal fuse 23 is melted by this heat. However, when the heater wire 7 and the sensor electrode 5 are repeatedly brought into contact with each other, Since the heat generated by the resistor 22 is small, the thermal fuse 23 remains unfused for a long time, and the electric blanket 1
Could be overheated.

In addition, the above-mentioned thermal fuse 23 is normally set to 1 after the temperature of the resistor 22 rises until the thermal fuse 23 is blown.
Since it takes about a minute, the electric blanket 1 may be overheated during that time.

Therefore, an object of the present invention is to immediately detect when the heating element (heater wire) and the sensor electrode are in contact (conduction) with each other via the heating conduction means (thermosensitive dielectric layer) and supply power to the heater wire. It is to provide a temperature control device that stops.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, the present invention provides a heating element connected between power supply terminals of an AC commercial power source via a power control element, and one end of the heating element. A sensor electrode having a temperature detecting function and a current passing function of the heating element connected to one of the power supply terminals of the AC commercial power supply, and the temperature of the heating element interposed between the heating element and the sensor electrode are A heating conduction means that conducts when a predetermined temperature is reached, a low withstand voltage type switching element connected in series to the sensor electrode that is destroyed when the AC commercial power source is applied when the heating conduction means conducts, An energization and heating timing control means for detecting the breakdown state of the switching element and controlling ON / OFF of the power control element is provided.

(Operation) According to the present invention, when the heating element (heater wire) is abnormally heated, the heating conduction means (thermosensitive dielectric layer) interposed between the heating element and the sensor electrode is conducted. By the conduction of the heating conduction means, an AC commercial power source, a thermal fuse, a heating element, a sensor electrode, and a switching element (low withstand voltage type, for example,
A closed loop with 30 V) is formed, and the voltage of the AC commercial power supply (for example, AC100 V) is applied to the switching element.
Then, a voltage much higher than the withstand voltage is applied to the switching element and the switching element is destroyed. One end of the sensor electrode is fixed to a constant potential due to the destruction of the switching element, and as a result, the energization heating timing control means (the energization control means for the heating element such as the drive circuit 37 and the comparison circuit 36 and the pulse for driving the switching element 59). The signal generation circuit 30) does not operate and the power control element does not turn on / off.
Therefore, the power supply to the heating element is immediately stopped,
For example, even if the thermal fuse is not blown off due to the intermittent contact between the heating element and the sensor electrode or the heat generation of the resistor is small as in the conventional case, there is no possibility that the electric blanket is overheated.

(Example) Hereinafter, the present invention will be described based on illustrated examples. In addition, the same reference numerals are given to the parts already described, and the duplicated description will be omitted.

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

As shown in FIG. 1, the temperature control device is an AC commercial power source.
First sync pulse signal, which will be described later, before and after the zero crossing point of 21
A pulse signal generating circuit 30 for respectively generating S10 and a second synchronizing pulse signal S11 and a low breakdown voltage type transistor 59 are provided, and one end side of the sensor electrode 5 is lowered to near the voltage VEE according to the second synchronizing pulse signal S11. A voltage applying circuit 31 for
A sensor output acquisition circuit 32 for generating a first temperature detection signal S14 (described later) according to the amount of charge flowing into the sensor electrode 5 and a reset signal S18 for controlling ON / OFF of the thyristor 17; 1. Temperature setting circuit that includes a sensor temperature detection circuit 33 that takes in the first temperature detection signal S14 and generates the first temperature detection signal S15, and a setting device such as a variable resistor, and that generates a temperature setting signal S16 corresponding to the temperature setting value A circuit 34, a sampling circuit 35 which supplies the temperature setting signal S16 to the comparison circuit 36 when the first synchronizing pulse signal S10 is supplied, a value of the temperature setting signal S16 and a first temperature detection signal S15. A comparator circuit 36 that compares the value with a value and generates a heater-on signal S17 under a predetermined condition, and a drive circuit 37 that generates a trigger signal S19 for the thyristor 17 under a predetermined condition.
A noise absorption circuit 39 that includes a series circuit including a resistor 75 and a capacitor 76, absorbs noise generated when the thyristor 17 is turned on and off, and a safety monitoring circuit 18 similar to that described above.

The outline of the operation of this temperature control device is as follows. This will be described with reference to the flowchart shown in FIG.

That is, before the zero-cross point of the AC voltage applied to the thyristor 17, the temperature of the electric blanket 1 and the set temperature set in the temperature setting circuit 34 are compared by the comparison circuit 36, and based on the comparison result, the thyristor 17 To turn on or off. Thereby, normal temperature control of the electric blanket 1 is performed.

Regarding the operation of the safety monitoring circuit 18, after the zero-cross point, the transistor 59 of the voltage application circuit 31 is turned on so that one end of the sensor electrode 5 in the electric blanket 1 is at the potential V.
Reduce to EE. At this time, the sensor electrode 5 and the heater wire 7
If and are not in contact (conduction), the voltage application circuit 31 and the drive circuit 37 operate normally as described later.
On / off control of 17 becomes possible. If the thermosensitive dielectric layer 6 is destroyed and the sensor electrode 5 and the heater wire 7 are electrically connected, the AC commercial power source 21 (21a) → the thermal fuse 2
3 → heater wire 7 → conduction of thermosensitive dielectric layer 6 → sensor electrode 5 →
Transistor 59 → VEE [AC commercial power supply voltage VCC (100
V) −5V], AC commercial voltage (AC100V) is applied between the collector and emitter of the transistor 59, and the low breakdown voltage type (eg, 30V) transistor 59 is destroyed. ON / OFF control is stopped. This prevents abnormal overheating of the electric blanket 1.

That is, when the transistor 59 has “open failure”, the pulse output from the second pulse generator 53 is the transistor 69.
Since the transistor 69 is off, the transistor 72 is off, and the reset signal S18 maintains the "L0" level. At this time, even if a set pulse is applied to the flip-flop circuit 55 from the output terminal of the comparison circuit 36, the output terminal Q remains at the "H0" level. The thyristor 17 is turned on and off during the first half cycle of the AC commercial power supply, but since the output terminal Q does not become the "L0" level from the next half cycle, it is not possible to store charge in the capacitor 56 and the thyristor. I can't turn on 17. When the set pulse is not given to the flip-flop circuit 55 from the output of the comparison circuit 36, the output terminal Q is "L".
Due to the 0 "level, thyristor 17 remains off.

On the other hand, even when the transistor 59 has a “close failure”, the pulse output S11 from the second pulse generator 53 is not transmitted to the transistor 69, the transistor 69 is on, the transistor 72 is on, and the reset signal S18 is The "H0" level is maintained. Therefore, the output terminal Q of the flip-flop circuit 55 is at the "L0" level (reset priority) regardless of whether the output of the comparison circuit 36 is at the "H0" or "L0" level, so that the thyristor 17 remains off. .

Next, details of each component other than the above-mentioned outline description will be described with reference to the time chart shown in FIG.

The pulse signal generation circuit 30 includes resistors 50 and 51 inserted at both ends of the AC commercial power supply 21, and an AC applied to the thyristor 17 based on the voltage obtained at the connection point of the resistors 50 and 51. A first pulse generator 52 that generates a first synchronization pulse signal S10 slightly before the voltage changes from negative to positive (a little before the zero-cross point), and a second synchronization after the AC voltage changes from negative to positive. Second pulse generator 5 for generating pulse signal S11
2 and supplies the first and second synchronization pulse signals S10 and S11 to the sampling circuit 35 and the voltage application circuit 31, respectively.

The sensor temperature detection circuit 33 receives the first temperature detection signal from the sensor output acquisition circuit 32 which acquires the output of the sensor electrode 5.
When S14 (described later) is output, this is taken in and the first temperature detection signal S15 is generated and supplied to the comparison circuit 36.
In this case, if the temperature of the electric blanket 1 decreases, the value of the first temperature detection signal S15 correspondingly increases.

The sampling circuit 35 uses the first sync pulse signal S10.
Is not supplied, the voltage of the output terminal T2 is held at the power supply voltage Vcc. And in this state, the first
When the sync pulse signal S10 is supplied, the temperature setting circuit 34
The temperature setting signal S16 output from
Supply to.

The comparison circuit 36 outputs the output of the sampling circuit 35 (temperature setting signal S16) and the first output from the sensor temperature detection circuit 11.
The sampling circuit 35 is provided with an operational amplifier 54 for comparing the value of the temperature detection signal S15 with the output terminal voltage of the power supply voltage Vcc.
The output pin is set to "Lo" level when held at. Then, when the temperature setting signal S16 is output, the value of the temperature setting signal S16 is compared with the value of the first temperature detection signal S15, and when S15> S16 (electric blanket 1
Temperature is lower than the temperature set by the temperature setting circuit 34),
A heater-on signal S17 is generated and supplied to the drive circuit 37.

The drive circuit 37 is set when the heater-on signal S17 is supplied, and then the reset signal S18 (described later)
RS-type flip-flop 55 that is reset when is supplied, and the set output terminal of the flip-flop 55 is "L"
A capacitor 56 that is charged when it is at the level and discharged when it is at the “H” level, a resistor 57 that determines the charging / discharging time constant of the capacitor 56, and the current discharged from the capacitor 56 as a voltage. A resistor 58 for converting and generating the trigger signal S19 is provided, and when the heater-on signal S17 is supplied, the trigger signal S1 is generated by the charge stored in the capacitor 56.
9 is generated and supplied to the gate of the thyristor 17.

In this way, the AC commercial power supply 21
When a forward voltage is applied to the thyristor 17, the thyristor 17 becomes conductive, and one end 21a of the AC commercial power source 21 → thermal fuse 23 → heater wire 7 → anode of the thyristor 17 and cathode of the thyristor 17 → AC commercial power source 21 In the path of the other end 21b, a current flows through the heater wire 7 and the temperature of the electric blanket 1 rises.

After this, when the reset signal S18 is supplied, the drive circuit 3
7 stops generating the trigger signal S19 described above,
Let 56 charge.

The voltage application circuit 31 is of a low withstand voltage type (for example, 30 V) that is turned on when the second synchronization pulse signal S11 is output.
V) transistor 59, a resistor 60 for limiting the base current interposed between the base of the transistor 59 and the output terminal of the second pulse generating circuit 53, the collector of the transistor 59 and one end of the sensor electrode 5. And a resistor 61 for voltage division interposed between the two electrodes, and lowers one end side of the sensor electrode 5 to near the voltage VEE when the second synchronizing pulse signal S11 is output.

The safety monitoring circuit 18 includes a resistor 22 connected to the other end of the sensor electrode 5 and a temperature fuse 23 that melts due to the heat generated by the resistor 22. When the heater wire 7 is in contact (conduction), AC commercial power supply 21 (21a) → thermal fuse 23 → heater wire 7 → sensor electrode 5 → resistor 22 → resistor 19 → AC commercial power supply 21 (21
By the route of b), the resistor 22 generates heat due to the current flowing from the heater wire 7 to the sensor electrode 5, and the thermal fuse 23 is melted (broken), and the power supply from the AC commercial power source 21 to the heater wire 7 is cut off. .

The sensor output acquisition circuit 32 includes a current-voltage conversion circuit 62, a signal polarity limiting circuit 63, and a disconnection check circuit 64, and in a state where one end side of the sensor electrode 5 is not lowered to near the voltage VEE by the voltage application circuit 31, When a voltage is applied to the heater wire 7 and an electric charge flows into the sensor electrode 5 by a dielectric constant corresponding to the temperature of the thermosensitive dielectric layer 6, the first temperature detection signal S14 having a value corresponding to the electric charge is generated. Supply to the sensor temperature detection circuit 11.

When one end side of the sensor electrode 5 is lowered to near the voltage VEE by the voltage application circuit 31, the sensor electrode 5
Check if the other end of the voltage drops to near VEE. If the other end of the sensor electrode 5 has dropped to near the voltage VEE, a reset signal S18 indicating that the sensor electrode 5 is not broken is generated as described later, and this is set to the R
It is supplied to the S-type flip-flop 55 to be reset.

The current-voltage conversion circuit 62 includes a current-voltage conversion resistor 65 inserted between one end of the resistor 22 and the cathode of the thyristor 17, and a noise absorption capacitor connected in parallel with the resistor 65. 66, and when the one end side of the sensor electrode 5 is not lowered to near the voltage VEE by the voltage application circuit 31, the first temperature detection signal having a value corresponding to the amount of electric charge flowing into the sensor electrode 5. Generate S14,
This is supplied to the sensor temperature detection circuit 11.

The signal polarity limiting circuit 63 includes three diodes 67a, 67b, 67c connected in series, and when the connection point voltage between the resistor 65 and the resistor 22 is about to exceed a predetermined value in the positive polarity direction. , Clipping the first temperature detection signal
It prevents the value of S14 from becoming positive.

The disconnection check circuit 64 includes a diode array 68 that conducts when the connection point voltage between the resistor 65 and the resistor 22 becomes a predetermined value or less, and a transistor that turns on when the diode array 68 conducts. 69 and the transistor
Resistors 70 and 71 that divide the collector voltage of 69, and transistor 72 that turns on when transistor 69 turns on and the connection point voltage of these resistors 70 and 71 drops.
And a resistor 73 for extracting the collector voltage of the transistor 72. Then, the voltage applying circuit 31
When one end side of the sensor electrode 5 is lowered to near the voltage VEE by the above, if the other end of the sensor electrode 5 is lowered to near the voltage VEE, the reset signal S18 indicating that the sensor electrode 5 is not broken is given. It is generated and supplied to the RS flip-flop 55. On the contrary, the connection point voltage between the resistor 65 and the resistor 22 is a predetermined value or more (for the reason described later)
Then, the reset signal S18 is not generated, the flip-flop 55 is not reset, and the trigger signal S19 is not generated, so that the thyristor 17 is not conducted.

As described above, in the present embodiment, after determining whether the thyristor 17 is turned on or off, the transistor 59 of the voltage application circuit 31 is turned on so that one end of the sensor electrode 5 is at the potential VEE.
To lower. At this time, if the sensor electrode 5 and the heater wire 7 are not in contact with each other, the drive circuit 37 is reset and the thyristor 17 can be controlled to be turned on and off.

If the thermosensitive dielectric layer 6 is destroyed and the sensor electrode 5 and the heater wire 7 are brought into contact (conduction), the AC commercial power source 21
(21a) → thermal fuse 23 → heater wire 7 → thermosensitive dielectric layer 6
AC voltage (AC100V) is applied between the collector and the emitter of the transistor 59 by the path of conduction of the sensor electrode 5 → transistor electrode 5 → transistor 59 → VEE [voltage of AC commercial power source VCC (100V) -5V], and a low breakdown voltage type (for example, The transistor 59 is destroyed by the path of 30 V), the trigger signal S19 is not applied to the gate of the thyristor 17 from the drive circuit 37 as described above, and the on / off control of the thyristor 17 is immediately stopped.

After that, the current output from the AC commercial power supply 21 is supplied from the heater wire 7 to the sensor electrode 5, and the resistor 22 generates heat,
The thermal fuse 23 is melted. As a result, the application of the AC commercial power supply 21 to the heater wire 7 is completely stopped.

Although the low breakdown voltage type transistor 59 is used in this embodiment, a low voltage type FET (field effect transistor) or the like may be used instead.

As described above, according to the present invention, when the heating element (heater wire) and the sensor electrode are electrically connected to each other, an AC commercial power source is applied to the switching element to destroy the switching element and control the power. Since the on / off operation of the element is stopped, the power supply to the heating element is immediately stopped.
It is possible to eliminate the risk that the electric blanket or the like will be overheated abnormally.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of a temperature control device of the present invention,
FIG. 2 is a time chart of the same embodiment, FIG. 3 is a block diagram of a conventional temperature control device, and FIG. 4 is a perspective view showing a structure of a one-wire system. 1 ... Electric blanket 3 ... 1-wire type wire 5 ... Sensor electrode 6 ... Heat sensitive dielectric layer (heating conducting means) 7 ... Heater wire (heating element) 17 ... Thyristor (power control element) 21 ... AC Commercial power supply (AC commercial power supply) 22 ...... Resistors connected in series to the sensor electrode 23 ...... Temperature fuse 30 ...... Pulse signal generation circuit (energization timing control means) 31 ...... Voltage application circuit 32 ...... Sensor output acquisition circuit 33 …… Sensor temperature detection circuit 34 …… Temperature setting circuit 36 …… Comparison circuit (energization timing control means) 37 …… Drive circuit (energization timing control means) 53 …… Second pulse generator (energization timing control means) 59 ...... Transistor (switching element) 64 ...... Disconnection check circuit (energization timing control means)

Claims (1)

(57) [Claims] 1. A heating element connected between power supply terminals of an AC commercial power source via a power control element, and a temperature detecting function of the heating element having one end connected to one power supply terminal of the AC commercial power source. And a sensor electrode having a current passing function, a heating conduction unit that conducts when the temperature of the heating element interposed between the heating element and the sensor electrode reaches a predetermined temperature, and the heating conduction unit conducts. A low withstand voltage switching element connected in series to the sensor electrode, which is sometimes destroyed by the application of the AC commercial power source, and energization for detecting the breakdown state of the switching element and controlling ON / OFF of the power control element. And a heating timing control means.