JPS6259805B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a temperature control device used for electric heating appliances such as electric blankets, electric sheets, and electric floor heaters, as well as heating appliances that use gas, kerosene, etc. A semiconductor control element (for example, a commercially available SCR) is used as a power control element to control power supply.
It relates to a temperature control device that uses a SCR (hereinafter referred to as SCR), and has improved fail-safe features such as self-triggering of the SCR to prevent unsafe operation due to failure of the power control element.

Conventionally, when an SCR is used as a power control element to control power to a load, a half-wave current flows as the load current during normal control, but a full-wave current flows when the SCR shorts, so the full-wave current flows when the SCR shorts. A system that protects circuits by distinguishing between the waveforms of wave current and half-wave current and blowing power circuit breakers, such as current fuses, has been put into practical use and has shown some effectiveness. However, when an SCR develops a diode-like failure, or a so-called self-trigger failure, a half-wave current that is almost the same as when the SCR is in normal operation flows through the load, making it no longer possible to use conventional waveform identification methods. Failure detection is not possible. Therefore, when this fault occurs, conduction continues even if there is no SCR control signal, and the load temperature rises abnormally, causing burns and
This may result in harm to the human body such as fire or electric shock.

Conventionally, when a diode-like failure occurs in an SCR as described above, safety is ensured by detecting the resulting abnormal state, such as an abnormal temperature rise (overheating) in the load. This is so-called indirect detection. Because of this, I was concerned about safety.

The present invention relates to a terminal voltage of a power control element such as an SCR that directly or indirectly controls power supply to a load,
The self-trigger failure of the power control element is directly detected by logic with the sensor output that controls on/off of the power control element, thereby improving safety. The method of the present invention is particularly effective for detecting self-triggering of SCR.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an outline of an electric blanket or electric sheet as an embodiment of the present invention. In Figure 1, 1
is a power plug for connecting to an AC 100 volt power source, 2 is a controller box, and 3 is a heated object, which is a blanket for an electric blanket and a sheet for an electric bed. 4 is a connection cord, 5 is a connector, 6 is a heater, 7 is a temperature sensor arranged to detect the temperature of the heated object 3, 8 is a power switch, 9 is a temperature setting for setting the temperature of the heated object 3 A knob 10 is a switch for switching the temperature of the heated object 3 between two control modes as shown in FIG. One of the two control modes is a ratio control mode in which the temperature of the heated object 3 is always controlled to be a constant temperature, and the other is a ratio control mode in which the temperature of the heated object 3 is controlled within a predetermined temperature range. It is a hysteresis control mode that swings with. Reference numeral 11 denotes a switch for starting strong scale operation, and by operating this switch, two control modes are selected as shown in FIG. One is that the object to be heated 3 is heated at a high scale temperature for a predetermined period regardless of the temperature set by the temperature setting knob 9, and then the temperature returns to the temperature set by the temperature setting knob 9 and the temperature increases. It is a high hold mode to control. The other one is control without the above-mentioned high hold function, that is, a normal mode in which control is performed at the temperature set by the temperature setting knob 9.
12 is a power pilot lamp, and 13 is a pilot lamp that lights up when the heater 6 is energized.

FIG. 2 shows the entire electrical circuit in one embodiment of the present invention. In FIG. 2, 1 is a power plug, 8 is a power switch, and 14 is a temperature fuse. Reference numeral 15 denotes a noise filter section of the power supply, which is composed of a choke coil 16, a capacitor 17, and a surge absorber 18. 12 is a power pilot lamp, and 64 is a supplementary resistor for the lamp 12. 19 is a circuit that obtains the control power supply V _CC , and the diode 2
0, resistors 21 and 22, capacitors 23 and 24, and Zener diode 25. Reference numeral 26 denotes a temperature setting circuit, which is composed of a volume 27 whose resistance value changes depending on the setting of the temperature setting knob 9, and a limiting resistor 28. 29 is a temperature detection circuit, which includes a neon lamp 30 as a pulse trigger element and a capacitor 3.
1, a resistor 32, a pulse transformer 33, and a temperature sensor 7. The temperature sensor 7 has a structure as shown in FIG. 3, in which a winding 36 is wound around a core wire 39 in the form of a coil, the outer periphery of the winding 36 is covered with a temperature-sensitive material 38 made of a plastic thermistor, and a winding 37 is wound around the outer periphery of the winding 36. , is a string-like sensor covered with an epidermis 40. The interlayer impedance Z ₇ of windings 36 and 37 is
The characteristics of the temperature-sensitive material 38 change depending on the temperature, resulting in characteristics as shown in FIG. In this temperature detection circuit 29, a setting resistance R _x determined by the temperature adjustment volume 27 (the sum of the value R ₂₇ of the volume 27 and the value R ₂₈ of the limiting resistor 28, R _x = R ₂₇ + R ₂₈ ) and the temperature sensor 7 The _voltage is divided by _the impedance _{Z7 of}
<V _Z7 , the neon lamp 30 is triggered and an output is output from the pulse transformer 33 via the capacitor 31 and resistor 32. At this time, the temperature of the heated body 3 is low. When V _BO > V _Z7 , neon lamp 30 does not trigger. At this time, the temperature of the heated object 3 is high. Reference numeral 41 denotes a control circuit which is the main body of control, and is composed of an integrated circuit (hereinafter simply referred to as IC). This IC is 1~
It has pins marked 16. The resistor 42 detects the AC line voltage and synchronizes the IC 41 with AC. Strong scale holding switch contacts 56', 5
6'' has a configuration that is closed by pulling the strong scale holding knob 11, and is connected to pin 3 of the IC 41. 43 is a C/R circuit for triggering a thyristor 47, which will be described later, and is composed of a resistor 44 and a capacitor 45. In the trigger C/R circuit 43,
The output of the temperature detection circuit 29 (output when the temperature of the heated object is lower than the set value) is received at pin 2 of IC41, and the output from pin 14 is applied to resistor 44.
The capacitor 45 is charged via. after that,
At the zero point, where the AC line voltage goes into the positive cycle and crosses zero voltage, it discharges through pin 13 and 12
The zero cross of the thyristor 47 is triggered from the pin. 46 is a gate resistor, and 47 is a thyristor that drives the heater 6. The heater 6 has a configuration as shown in FIG.
is wound into a coil shape, and the outer periphery is covered with hot melt resin 50
This is a string-like heater in which a safety wire 49 is wound around the outer periphery in a coil shape, and a skin 52 is also wrapped around the outer periphery. If this heater 6 becomes abnormally high temperature due to some kind of accident, the resin 50 will melt and the heater wire 4 will melt.
8 and the safety line 49 come into contact. Then, A in Figure 2
Point - Heater wire 48 - Contact part - Safety wire 49 - Resistance 5
A large current flows through the circuit at point 5-B, causing the resistor 55 to generate heat, which heats and blows out the temperature fuse 14, thereby performing a safety operation of shutting off the power supply. Under normal conditions, a small current of a temperature detection signal flows through the circuit of the resistor 55, the safety wire 49, the temperature sensor 7, and the temperature setting volume 27, but this current does not cause the resistor 55 to generate heat. Next, to explain the configuration related to the strong scale retention release function, pin 10 of the IC 41 is the release output terminal for the strong scale retention function, and when the gate resistor 53 and thyristor 54 are triggered, the coil 56 is energized. , the contacts 56' and 56'' of the strong scale holding switch are opened.Next, the configuration related to the safety operation of the self-triggered state of the thyristor 47 will be explained. 57 is a resistor;
This is to check the terminal voltage of the thyristor 47 that drives the heater 6. Temperature detection circuit 29
The state in which the thyristor 47 is conducting half-wave even though there is no output and therefore no input to the second pin of the IC 41 is a dangerous state in which the thyristor 47 is self-triggering. In this state, the terminal voltage of the thyristor 47 is received at the 15th pin of the IC 41 via the resistor 57, a logical operation is performed within the IC 41, and a trigger output for the thyristor 58 is outputted from the 11th pin. As a result, the thyristor 58 becomes conductive.
The resistor 59 generates heat, heats the temperature fuse 14, blows it out, and performs a safety operation to shut off the power. Next, we will explain the safety function when the thyristor 47 causes a complete shot failure. At this time, excessive power is applied to the heater 6, which is dangerous.
A negative half-cycle voltage is applied to the resistor 62 via the diode 61, which causes the resistor 62 to generate heat, which heats and blows the temperature fuse 14, stopping the power supply.

FIG. 8 shows the control block of IC41. In FIG. 8, the inside of IC41 is surrounded by a two-dot chain line. Also, among the external parts of IC41,
Components unrelated to the gist of the present invention are omitted. In Fig. 8, A is a reset section, B is a zero pulse generation section, and AC is the time base for IC control.
A zero-crossing voltage of the line voltage is detected via a resistor 42 to generate a zero-crossing pulse. C is a waveform shaping section that converts the output of the temperature sensor 7 into a pulse transformer 3.
3 in the form of pulses and shaped into a specified waveform. D is a 2-bit frequency divider which inputs the temperature detection output of the waveform shaping section C and generates a trigger pulse for the thyristor 47 when the AC line voltage goes positive or goes negative. E
is a charging amplifier section that charges a capacitor 45 via a resistor 44. F is a discharge amplifier section, which takes in the charge accumulated in the capacitor 45 from pin 13 and outputs it to 12
The thyristor 47 is triggered by discharging from the pin.
G is a hysteresis control switching unit which receives a signal from the switch 10, which is closed when hysteresis control is selected, from pin 4. H is a hysteresis control logic section, which stops the 2-bit frequency dividing section D for the time Δt _A shown in FIG. I is a first counter constructed by connecting n stages of T-type flip-flops, and counts the power supply frequency for the time Δt _A described in the above-mentioned hysteresis control logic section H, and the thyristor 47 is stopped during this period. When the counter I times up, the reset section A resets the hysteresis control logic section H and gives a trigger to the thyristor 47 again. K is a second counter constructed by connecting two stages of T-type flip-flops, and has a strong scale holding period Δ, which will be described later.
Determine _tA . J is a strong scale holding switching section.
When the strong scale holding knob 11 is operated, contact 5
6' and 56'' are closed. Since the temperature setting volume 27 is short-circuited by the closing of the contact 56', the maximum temperature is set regardless of the setting of the volume 27. Also, the closing of the contact 56 is closed from the 3rd pin. In response, the strong scale holding switching unit J directly connects the counter I for hysteresis control and the counter K for strong scale holding, and uses the counters I and K to count the strong holding time Δt _H shown in FIG. In addition, if the strong scale holding switching unit J is set to strong scale holding even during hysteresis control operation, the function of the hysteresis control switching unit G will be lost during strong scale operation as shown in FIG. Proportional control.L is a memory for holding strong scale.This memory L is for sharing the first counter I as a lower counter for holding strong scale. At time, the signal of the time-up of the first counter I is stored in the memory L, and the input is input to the second counter K for holding the strong scale.M is an output amplifier for canceling the strong scale holding; The thyristor 54 is triggered by the amplifier output, and the coil 56 opens the contacts 56' and 56'' for maintaining the high temperature. Furthermore, detection of a diode failure of the thyristor 47, that is, detection of self-triggering, is performed using the thyristor 47.
This is performed using the logic of a terminal voltage detection section N and a waveform shaping section C, which detect the terminal voltage of . For example, if there is no output from the waveform shaping section C but no input voltage from the voltage detection section N, it is an abnormality (self-triggered state), so the timing detector O switches at an appropriate phase of the positive cycle of the power supply. An output is generated at this timing and is amplified by the self-trigger amplifier P. This output triggers the thyristor 58, and the heat generated by the resistor 59 blows out the temperature fuse 14.

FIG. 9 shows a logic diagram of the present electrical circuit. Each block A to Q in FIG. 8 is surrounded by a broken line in FIG. In FIG. 9, G ₁ ~
_G28 is a gate made using the IIL process, the input is equivalent to the base of a transistor, and the output is an open collector multi-transistor type. RS ₁ to _{RS 5} are reset-set type flip-flops, which are also made using the IIL process. T is a T-shaped flip-flop, the input is shown as Q, and the output is shown as Q. Further, a to Q shown by solid square blocks are analog circuits made with a normal bipolar configuration. Before explaining the logic with reference to FIG. 9, the bipolar sections a to Q will be explained.

First, the reset voltage detection circuit a using the control power supply V _CC of the reset section A will be explained. 10th
The figure and FIG. 11 show an example of the circuit, and FIG. 12 shows the waveform of its operation. In FIGS. 10 and 11, when the control power supply V _CC of pin 1 is increased from OV, the transistor a ₅ is off until a certain threshold value V _RS , and when this V _RS is exceeded, it enters the on region. This threshold value V _RS becomes a voltage of V RS =3×V _BE , where the base-emitter voltage V _BE of the transistors a ₂ to a ₄ is taken as V _RS . In the circuit of FIG. 10, transistor a ₄ ,
_a5 constitutes a current mirror circuit, and V _CC ≧
A current I ₁ begins to flow through the resistor a ₁ from the point where V _RS is reached, and a current approximately equal to this current I ₁ is drawn between the collector and emitter of the transistor a ₅ . The circuit in Figure 11 operates the current mirror in the circuit in Figure 10 as a current amplifier, so transistor a ₄
is changed to resistor _a6 .

FIG. 12 shows this operation. When the power switch 8 is turned on, the capacitors 23 and 24 of the power supply section 19
As a result, the control power supply V _CC rises with time as shown by V _CC in FIG. 12A. Assuming that _{V RS} is the reset voltage, transistor a ₅ is off until time t _R2 as shown in the waveform _B in _{FIG .} It is completely turned on at time Δt. Now, if the operating voltage of the logic section is V _L , the logic section enters normal operation at time t _R1 , but during this period it is reset by transistor _a5 , and at time t _R2 , transistor _a5 turns on. , the reset of the logic section is released. Furthermore, when a current amplifier is used instead of a count mirror, the switching time Δt of transistor _a5 is shortened, as shown in the waveform of FIG. 12B, and good operation is exhibited.

FIG. 13 shows another circuit example of the reset voltage detection circuit a, in which the reset threshold voltage V _RS is determined by the differential amplifier formed by the transistors a ₇ and a ₈ by the transistors a ₂ , a ₃ , and a ₄ . and this voltage V _RS
and v _CC determined by the divided voltage of resistors a ₁₃ and a ₁₄ are detected, and the operation of transistor a ₅ is determined.

In short, the reset voltage detection circuit a detects the voltage rise of the control power supply V _CC from the time when the power is turned on _.
is detected, and when the control power supply V _CC is lower than the set threshold V _RS , transistor _a5 is turned off,
Reset the logic section.

Next, zero voltage detection circuit b of zero pulse generation section B
I will explain about it. FIG. 14 shows an example of the circuit, and FIG. 15 shows the waveforms of its operation. In the circuit shown in Figure 14, when the power supply voltage V _AC is applied between the 16th pin and the 5th pin, the waveforms "b14's V _CE " and "b19's V _CE " shown in FIG. The purpose is to obtain ``V _CE ''. 1st
The operation of the circuit in FIG. 14 will be described with reference to time t ₀ when the power supply voltage V _AC in FIG. 5 is at zero voltage. 16
When the power supply voltage V _AC applied to the pin starts to go positive, a current shown as "I _CE of b ₁₁ " in FIG. 15 begins to flow between the collector and emitter of transistor b ₁₁ . The power supply voltage V _AC at this time is transistor b ₁₁
That is, the base-emitter voltage V _BES of transistor b ₈ biased by resistor b ₇ is used as the bias voltage, and the base-emitter voltage V _BE of transistor b ₁₁ is added, exceeding 2V _BE ≒ V _BE + V _BES It's time. This time Δt _P is expressed by the following formula.

Δt _P =1/2π·sin ⁻¹ 2V _BE /V _AC However, it is the power supply frequency.

This _ICE of transistor b ₁₁ turns on the current mirror composed of transistors b ₁₃ and b ₁₄ via transistor b ₁₂ , and "b _14" in FIG.
The operation is ``V <sub>CE</sub> ''. After that, the power supply voltage V <sub>AC</sub>
begins to go negative beyond its peak value until just before time t <sub>1</sub> , i.e. until V <sub>AC</sub> ≥2V <sub>BE</sub>
b <sub>14</sub> remains on. Thereafter, when V <sub>AC</sub> <2V <sub>BE</sub> , the transistor b <sub>14</sub> is turned off, resulting in a waveform like the "V <sub>CB</sub> of b <sub>14</sub> " waveform in FIG. 15. Note that the transistor b <sub>10</sub> and the transistor b <sub>11</sub> constitute a current mirror in pair. For reference, a current mirror consists of a base current I <sub>B</sub> flowing through a resistor b <sub>1</sub> and a resistor b <sub>3</sub>
The collector current I <sub>C</sub> flowing in the current I B is approximately I <sub>B</sub> ≒ I <sub>C</sub> . b <sub>20</sub> is a waveform shaping circuit inserted to increase the switching speed of transistor b <sub>14</sub> , and is shown in Fig. 16 and 1, which will be described later.
The configuration is as shown in FIG. 7, and the input voltage phase and output voltage phase of this circuit are in the same phase. Next, the power supply voltage V <sub>AC</sub> in Figure 15 is
When starting to go negative from zero voltage with t <sub>1</sub> as a reference, the base voltage of the transistor b <sub>15</sub> is held at the base voltage of the transistor b <sub>18</sub> , that is, the aforementioned bias voltage V <sub>BES</sub> . If the base-emitter voltage of transistor <sub>b15</sub> is <sub>VBE</sub> , then <sub>VBE</sub> >V
When <sub>BES</sub> , V <sub>BES</sub> -V <sub>BE</sub> =-ΔV <sub>BE,</sub> the operation is as follows. That is, transistor b <sub>15</sub> is the above |
Turns on when V <sub>AC</sub> |>|ΔV <sub>BE</sub> |. At this time, the base current of the transistor b <sub>15</sub> flows from the control power supply V <sub>CC</sub> through the resistor b <sub>7</sub> , from the base of the transistor b <sub>15</sub> to the emitter, and through the resistor b <sub>1</sub> to the power supply V
Drains into <sub>AC</sub> . This time is delayed by Δt <sub>N</sub> with respect to time t <sub>1</sub> . Therefore transistor b <sub>15</sub>
A current called "I <sub>CE</sub> of b <sub>15</sub> " <sub>in FIG. 15 flows through</sub> the collector of "b 15 I CE <sub>"</sub> in FIG <sub>.</sub> A waveform with a voltage of ``V _CE '' is obtained. This state continues until just before time _t2 . Also, V
When _BE = V _BES and V _BES - V _BE = 0, the operation is as follows. Since the V _BE of transistors b ₁₅ and b ₁₈ are the same, transistor b ₁₅ operates at the time of V _AC =OV, so the time Δt _N in FIG. 15 becomes Δt _N =O
becomes. That is, at times t ₁ and t ₂ , the operations of "I _CE at b ₁₅ " and "V _CE at b ₁₉ " in FIG. 15 are performed.
Then, when V _BE <V _BES , V _BES - V _BE = +ΔV _BE , V _BE > V _BES , V _BES - V _BE = -ΔV _BE
Contrary to the case of , the time Δt _N in FIG. 15 is to the left, that is, to the front, of the time t ₁ . However, it does not advance to the time Δt _P shown in FIG. 15.

In short, transistors b ₁₄ and b ₁₉ switch as shown in FIG. 15. The output waveform is further processed by the waveform shaping section shown in FIGS. 16 and 17.
It is formatted by b ₂₀ and b ₂₁ .

In the circuit shown in Fig. 16, the transistor _b14 is a multi-collector, and the waveform is shaped by an RS flip-flop (consisting of gates _G31 and _G32 ) including the gate _G30 , so that the output of the gate _G31 has a sharp waveform. Become.

The circuit shown in FIG. 17 is an example in which an amplifier with an IIL configuration is used as the waveform shaping section b ₂₀ , and includes an injector resistor b ₂₁ , a gate composed of transistors b ₂₂ and b ₂₃ , and a transistor that amplifies this current.
It consists of an amplifier consisting of _B24 and _B25 .

Next, the pulse detection circuit c of the waveform shaping section C will be explained. Fig. 18 shows an example of the circuit, and Fig. 19 shows an example of the circuit.
The figure shows the waveform of that operation. In Figure 18,
When the temperature of the heated body 3 is low, the impedance Z ₇ between the windings 36 and 37 of the detection wire 7 is high. Therefore, when the power supply voltage V _AC in FIG. 19 rises to a specified voltage, the interlayer voltage V _Z7 of the detection line 7 increases
The neon lamp 30 is triggered when the discharge starting voltage V _BO becomes higher than that of the neon lamp 30 . Therefore, pulse transformer 3
In the secondary winding 35 of No. 3, a pulse having the tp waveform shown in FIG. 19 is obtained. In the transformer 33, when the trigger pulse of the neon lamp 30 when the power supply voltage V _AC is in the negative half cycle is transmitted from the primary winding to the secondary winding, the positive and negative are reversed, and the secondary winding ,t
The polarity of the winding is set to obtain a positive voltage pulse like _{the P1} waveform. Therefore, the configuration is such that the temperature is detected when the power supply voltage V _AC is in the negative cycle, and the _tP2 waveform generated in the positive cycle becomes a negative voltage, so it has no relation to subsequent operations and is invalid. . Pulse voltage t _P1 is applied to pins 2 and 5 in Figure 18.
is applied between the pins, so the emitter follower transistor _C3 turns on, which turns on the transistor C3.
A current mirror consisting of C ₄ and C ₅ operates. In other words, as shown in Figure 19, the _{transistor
C5} will turn on. The pulse t _P2 is a negative voltage, and this pulse t _P2 is connected to the transistor C ₆ , the resistor
flows through C ₁ and transistor C ₃ is reverse biased, so transistor C ₅ is not turned on. In addition, from time t ₃ to _{t 4} in FIG. 19, neon lamp 3
0 indicates a non-triggering state, and transistor _C5 is not turned on.

In short, the pulse detection circuit c in FIG. 18 receives the pulse t _P1 generated in the negative cycle of the power supply voltage V _AC as an effective temperature detection signal.

The amplifiers E and F for triggering the thyristor 47 will be explained. FIG. 20 shows an example of the circuit. In FIG. 20, when the output of gate G ₁₀ drops to "0", resistors E ₁ and E ₂ are biased and turned on, and capacitor 45 is charged via resistor 44. Then, when the power supply voltage V _AC crosses zero voltage, the gate G ₁₁ momentarily drops to "0", and the amplifier F is turned on by biasing the transistors F ₅ and F ₆ through the resistors F ₁ and F ₂ . . By this operation, the charge accumulated in the capacitor 45 is momentarily discharged in a pulsed manner, and the thyristor 47 is triggered through the 12th pin. As will be explained later, Gate G ₁₀
When the capacitor 45 is fully charged, the gate _G11 is "1" and no discharge signal is input.

Next, the switching detection circuits g and j between the hysteresis control switching section G and the strong scale holding switching section J will be explained. FIG. 21 shows a circuit example of the hysteresis control switching section G, and FIG. 22 shows a circuit example of the strong scale maintenance switching section J. In FIG. 21, resistors g ₁ , g ₂ , g ₃ and transistors g ₄ , g ₅ constitute a current mirror. When the hysteresis control changeover switch 10 is closed, the transistor _g5 is turned off and the hysteresis control mode is set. The circuit configuration of the strong scale holding switching section J shown in FIG. 22 is exactly the same as the hysteresis control switching section G shown in FIG. When the contact 56'' of the strong scale holding switch is closed, the transistor 2
5 is turned off.

Next, the self-trigger output amplifier P and the strong scale hold release output amplifier M will be explained. 23rd
The figure shows a circuit example of a self-trigger output amplifier P. In FIG. 23, when the output of gate 25 falls to "0", transistors p ₅ and p ₆ are turned on and thyristor 58 is triggered through pin 11. The circuit configuration of the amplifier M for outputting strong scale hold release is the same as that shown in FIG. 23, so a description thereof will be omitted.

Next, the voltage detection circuit N and detection timing circuit O of the self-trigger detection section of the thyristor 47 will be explained. FIG. 24 shows examples of both circuits, and FIG. 25 shows waveforms of their operation. In FIG. 24, the voltage detection circuit N checks whether the thyristor 47 is on or off.
It consists of transistors n ₁ , n ₂ and transistors n ₃ , n ₄ , n ₅ , n ₆ , n ₇ . When transistor n ₅ turns on, 15
The voltage ΔVa between pin and pin 5 is the voltage between the transistor
The three base-emitter voltages of n ₄ , n ₅ , n ₆ are set to 3V _BE
Then, the formula becomes as below.

ΔVa≧3V _BE On the other hand, the forward voltage drop V _F between the anode and cathode of the thyristor 47 when the thyristor 47 is turned on is set so that V _F <3V _BE . Therefore, as shown in FIG. 25, when the thyristor 47 is off (no signal is applied to the gate), the power supply voltage V _AC is equal to the threshold voltage of the transistor _n4 .
During the time Δt _C exceeding 3V _BE , a collector current flows through the transistor n ₄ as shown in FIG. 25, “I _CE of n ₄ ”. As a result, the collector voltage of transistor _n7 becomes "0" as shown in "V _CE of _n7 " in FIG. Further, "V _CE of _n7 " is "0" until a time Δt _C before time t ₁ when the power supply voltage V _AC crosses zero voltage toward the negative side. Next, when the thyristor 47 is turned on, the transistors n ₄ and n ₇ are off, as shown from time t ₂ to t ₃ in FIG _.
V _CE ” is maintained. In addition, in the self-trigger timing detection circuit O, the power supply voltage V is connected to pin 16.
_AC is added. Transistors that make up a differential amplifier
The reference voltage for O ₁₁ and O ₁₂ is the voltage at the midpoint of the division between resistors O ₃ and O ₄ , V _ST , and if the base _{-emitter voltage of the transistor is V BE ,} then 2.5 V _BE =
_VST . The base-emitter voltage V _BE of the transistor O ₈ is divided by the resistors O ₃ and O ₄ (O ₃ =O ₄ ) to give 0.5 V _BE . Therefore, during the time when the voltage at pin 16 due to the power supply voltage V _AC exceeds the voltage V _ST , transistors O ₁₂ and transistors O ₁₃ and O ₁₄ , which form the current mirror, as well as transistors O ₁₅ and O ₁₆ , which form the current mirror, are turned on. do. This state is indicated as time Δt _S in FIG. 25.
The voltage at pin 16 also serves as the input to zero cross generator B, as shown in FIG. Therefore, the 15th
As shown in the figure, from the point in time when the power supply voltage V _AC exceeds V _AC >2V _BE , the current is shunted to the zero cross generator B through the resistor b ₁ shown in Figure 14, so the voltages at pins 16 and 5 are 2V _BE as shown in Figure 25
It rises gently from The time during which this voltage exceeds 2.5V _BE (meaning the fresh-hold voltage V _ST of the differential amplifier composed of transistors O ₁₁ and O ₁₂ ) shown in FIG. 25 becomes Δt _S. In this circuit, it is necessary to set Δt _S >Δt _C.

Next, a circuit Q for taking out the intermediate output of the multi-stage first counter I will be explained. FIG. 26 shows an example of the circuit. In FIG. 26, the first counter I is formed by connecting T-type flip-flops T _I in n stages, and is divided into two blocks: T _I1 to T _Ix and T _Iy to T _Io . In this counter I, if the output Q _Ix of one block is directly connected to the input _Ty of the other block, it becomes a directly connected counter. However, when checking the function of a circuit, if the number of counter stages is large, even if a high-speed rectangular wave is input to the first stage, it will take too long for the output _QIo of the final stage to appear. be. Therefore, when checking, disconnect pins 8 and 9, and check the operation of counters T _I1 to T _Ix (8
Check the operation of counters T _Iy to T _Io by inputting a square wave to pin 9
This circuit Q is inserted in the middle of the counter I in order to independently perform the determination based on the output of _Io and to shorten the time required to check the operation. In FIG. 26, transistors q ₄ and q ₅ constitute a constant voltage source. Transistor q ₆ serves as an output buffer, transistors q ₇ and q ₈ serve as input buffers, and transistors q ₇ and q ₈ have a current mirror configuration.

Next, the control operation will be explained mainly with reference to FIG.

First, the operation in the proportional control mode shown in FIG. 6 will be explained. At this time, the hysteresis control changeover switch 10 is open, and the contacts 56' and 56'' of the strong scale holding switch are open.In this state, the power switch 8 is turned on, and if the temperature of the heated body 3 is low, as shown in FIG. Carry out the driving operations shown in Figure 9.
By the gate _G13 of the zero pulse generator B in the figure,
As shown in FIG. 27, when gate _G13 is "O",
Flip-flop _RS1 of waveform shaping section C is reset. That is, the power supply voltage V _AC is continuously reset during the positive half cycle and for a short period of the negative cycle. Thereafter, when the pulse t _P1 from the temperature sensor 7 occurs, the flip-flop RS ₁ is set. At this time, the output of flip-flop RS ₁ changes from "1" to "0", so the gate
G ₉ is "0" → "1", gate G ₁₀ is "1" →
It becomes "0". Amplifier E due to “0” of gate _G10
turns on and starts charging the capacitor 45 through the resistor 44. That is, charging of the capacitor 45 is started after the neon lamp 30 is triggered by the temperature sensor 7. Then, just before the time t ₂ when the power supply voltage V _AC changes from a negative voltage to a positive voltage, the gate G ₁₃
changes from "1" to "0", and the flip-flop _RS1 is reset again. Due to this reset, the output of flip-flop RS ₁ becomes "0" →
Returns to "1". Therefore, the signal "1" → "0" inverted by the gate _G33 is transferred to the T-type flip-flop T.
Therefore, the output Q of T flip-flop T becomes "0" at the falling edge of the input →
Reverse to "1". When the output Q of this T flip-flop T becomes "1", the output of the gate _G11 becomes "0", and the gate _G10 is set to "1", stopping the charging of the capacitor 45 and discharging the discharge amplifier F.
Activate and output to pin 12. And time
Immediately after the power supply voltage V _AC exceeds t ₂ and enters a positive voltage, the gate G ₁₂ changes from “0” to “1”, so the output of the wire AND of gates G ₁₄ and G ₁₅ changes from “1” →
It drops to "0". The period during which the output of this wire AND is "1" is ΔT. That is, the gate _G12 is both "0" during the period. Even after this period of ΔT, the output Q of the T-type flip-flop T remains "1", but since the AND of gates G ₁₄ and G ₁₅ is "0", the gate G ₁₁ becomes "1", and the capacitor 4
Stop the discharge of 5. Therefore, the output of pin 12 is the time
ΔT ₂ is generated at the zero cross point of the power supply voltage V _AC near t ₂ to trigger the thyristor 47, and the heater 48 is energized by the conduction of the thyristor 47. Further, since the gate G ₁₁ returns from "0" to "1" after the ΔT time, the output of the gate G ₁₀ changes from "1" to "0" and starts charging the capacitor 45 via the resistor 44 again. Then, near time _t3 when the power supply voltage V _AC changes from a positive voltage to a negative voltage, a zero cross pulse ΔT and an AND output between the output of the flip-flop RS ₂ and the output of the gate G ₁₄ are generated again. time
Immediately before t ₃ , the AND outputs of gates G ₁₄ and G ₁₅ change from "0" to "1", so the output Q "1" of T-type flip-flop T is unlocked, and the gate
G ₁₁ drops to "0" and capacitor 45 again
discharge. At this time, gate G ₁₀ is “0” →
Since it becomes "1", the discharge to the capacitor 45 is stopped. At the same time, the AND output between the output of flip-flop RS ₂ and the output of gate G ₁₄ is also "0" →
It becomes "1". This output is further ANDed with the output Q of the T-type flip-flop T and is applied to the gate _G4 , so the gate _G4 changes from "1" to "0" and the gate
_G33 changes from "0" to "1" and is added to the input of the T-type flip-flop T. Then, after time ΔT after exceeding time t ₃ , the flip-flop RS ₂
Since the AND output between the output of the gate _G14 and the output of the gate G14 falls from "1" to "0", the gate _G4 changes from "0" to "1", and the gate _G33 changes from "1" to "0". At the falling edge of the gate _G33 , the output Q of the T-type flip-flop T returns from "1" to "0". That is, the T-type flip-flop T counts 1 with the set and reset signals of the flip-flop _RS1 , and then counts 2 with the AND of the set output Q of the T-type flip-flop T and the zero-cross pulse ΔT in which the power supply voltage V _AC goes negative. and return to the original
A so-called frequency divider operation is performed. Expressed differently,
Temperature is detected in one cycle when the power supply voltage V _AC is positive or negative, and based on this signal, a 2-bit thyristor trigger pulse is issued at the time of zero when the power supply voltage V _AC goes positive or negative. Although an SCR is used as the thyristor 47 in FIG. 9, it is convenient when a TRIAC is used depending on the device. Next, in Fig. 27, time t ₅
Until _t8 , the temperature of the heated object 3 rises above the set value and there is no trigger pulse for the neon lamp 30 from the sensor 7. At this time, flip-flop RS ₁ continues to be reset, so
The above operation is not performed. Furthermore, since the gate _G10 is "1" and the capacitor 45 is not charged, and the output Q of the T-type flip-flop is also "0" and the gate _G11 is also "1", the discharge amplifier F is also inoperative. It is. Therefore, the voltage at pin 12 is "0". The temperature of the heated body 3 decreases,
When the neon lamp 30 starts to trigger again, the above-described operation is performed to trigger the thyristor 47 and energize the heater 48. Through these series of operations, temperature control in the proportional control mode shown in FIG. 6 can be achieved.

Next, the hysteresis control mode shown in FIG. 6 will be explained. At this time, the hysteresis control changeover switch 10 is closed. switch 10
Due to the closed circuit, gate G ₁₉ changes from "1" to "0", and the gate
G ₂₀ changes from "0" to "1". Also, since gate G ₁ is already "1", gate G ₃ is "0" →
The value becomes "1", the gate _G22 also changes from "1" to "0", and the first counter for hysteresis control is reset. At the same time, the flip-flops RS ₃ and RS ₄ of the hysteresis control logic section H
Also, gate _G5 changes from "0" to "1" and the reset is released. In explaining the operating state of the hysteresis control mode, reference will be made to FIG. 9 and FIG. 28, and time _t1 in FIG. 28 will be used as the starting point of the explanation. From time _t1 to time _t5 , the circuit operates as described in FIG. 27, and the output from pin 12 is sufficient to trigger the thyristor 47, so that the heater 48 is energized. That is, since the pulse t _P is generated from the pulse trigger element 30, the temperature of the heated object 3 is increasing. and,
When the temperature of the heated body 3 reaches the set value, the neon lamp 30 is no longer triggered and the pulse t _P2 that has been occurring periodically disappears. When the extinction of this pulse is detected, it is determined that the temperature of the heated object 3 has reached the set value at time _t5 , the gate output from pin 12 to the thyristor 47 is stopped, and the energization to the heater 48 is stopped. However, the temperature of the heated body 3 is
There is a slight overshoot, so no pulse is generated for a certain period of time. Then, the temperature of the heated body 3 begins to drop,
The temperature drops to the specified temperature. That is, when the set temperature T _S or the temperature differential ΔT _S is set in advance, the temperature decreases to T _S -ΔT _S. Then, the neon lamp 30 is triggered again near time _T8 ,
A pulse t _P3 is generated. This time T _D is determined by the configuration and temperature of the heated object 3. Note that the time T _D in FIG. 28 corresponds to several cycles of the power supply voltage V _AC , but this is for illustration only and is actually quite long. Then, when pulse t _P3 occurs again,
The first counter I detects and counts the pulse t _P3 . The counting time of the first counter I is determined by the thyristor 47.
Continue to stop the trigger. This first counter I
At the time-up output, the gate output of the thyristor 47 is unlocked, and the triggering of the thyristor 47 is repeated again. The above operation is repeated while the hysteresis control changeover switch 10 is closed. Through this operation, a temperature swing ΔT _D shown in FIG. 6 is obtained. FIG. 28 shows a time chart of the above operation. In FIG. 28, from time _t5 to _t6 , the power supply voltage V _AC is negative and no pulse t _P is generated, so the flip-flop R _S1 of the waveform shaping section c is not set, and the output of the flip-flop R _S1 is "1". , the T-type flip-flop T for 2-bit frequency division is also inoperative. And time
After exceeding t ₆ and delaying by Δt _P time, gate G ₁₂ becomes “0” →
Since it becomes "1", the input of gate _G6 is the AND of the output of flip-flop R _S1 , the output of T-type flip-flop T, and the output of gate _G12 .
“1” becomes depressed to “0”. The flip-flop R _S3 is set by this gate G ₆ , and the output Q of the flip-flop R _S3 changes from "0" to "1", and the gate G ₈
changes from "1" to "0", and the output Q of the T-type flip-flop is locked at "0". Yotsute gate
Since G ₁₁ is unconditionally "1", the discharge amplifier F
is turned off, and the trigger output from pin 12 to thyristor 47 becomes "0". Next, during the period from time t ₇ to _{t 8} when the power supply voltage V _AC is at a negative voltage, the temperature of the heated object 3 decreases and the pulse t _P3 is generated from the neon lamp 30, the flip-flop R _S1 is set and the flip-flop R The output Q of _S1 changes from "0" to "1". At this time, the output Q of the flip-flop RS ₃ is "1" and is on standby, so the gate G ₇ is "1" →
It falls to "0" and with this output the flip-flop R _S4
is set, and the output Q of flip-flop R _S4 changes from "0" to "1". Then, at the zero cross point where the power supply voltage V _AC goes negative near time t ₉ , the output of the flip-flop R _S2 becomes "0" for a time ΔT →
It becomes "1". Therefore, the output Q of the flip-flop R _S4 is "1" and the output of the flip-flop R _S2 changes from "0" to "1", so the output of the gate _G21 , that is, the first stage of the first counter I for the hysteresis control counter. The input of flip-flop T _I1 momentarily drops to "0" by ΔT. At the edge of this input falling from "1" to "0", the output Q of the first stage counter T _I1 becomes "0" →
Changes to "1". Next, at time _t11 , when the power supply voltage V _AC goes negative, the input T of the first stage flip-flop T _I1 falls from "1" to "0" again.
The output Q of the first stage flip-flop T _I1 is “1” →
It returns to "0" and performs a 2-frequency division operation. Since the first counter I is a multi-stage counter as shown in FIG.
The frequency division operation described above is repeated in sequence. and time tn,
That is, when the time for the final n-stage flip-flop T _Io to time up has elapsed, the input of the first-stage flip-flop T _I1 becomes "1" just before time tn.
→At the edge that falls to "0", the output Q of the final stage flip-flop T _Io changes from "0" to "1" and a time-up occurs. This final stage flip-flop T _I1
Since the output Q of becomes "1", the first counter I
A reset is applied from T _I1 to T _IZ . At the same time, the output of the gate _G5 changes from "1" to "0", and the flip-flops R _S3 and R _S4 of the hysteresis control logic section H are reset, returning to the initial state. That is, the gate _G8 returns from "0" to "1" and the output Q of the T-type flip-flop T is unlocked. The state in which this reset is applied is at time tn
It continues until just before +1 (time Δt _N before). Then, the rise of a positive zero-cross pulse ΔT (state in which the power supply voltage V _AC goes from negative to positive) consisting of the AND of the output _Q of the flip-flop RS ₂ and the output of the gate G 15, that is, the transition from "0" to "1". Due to the change, gate G ₁₆ changes from “1” to “0” and gate G ₂₃ changes from “0” to
It becomes "1", and the final stage flip-flop T _Io of the first counter I is reset. Therefore, since the output Q of the final stage flip-flop T _Io falls from "1" to "0", the flip-flops T _I1 to T _IZ of the first counter I are released from reset. That is, the reset is applied continuously during the negative half cycle period of the power supply voltage V _AC from time tn to tn+1 to ensure that the initial state is returned. Furthermore, in the final stage flip-flop T _Io , when the output Q of the final stage flip-flop T _Io falls from "1" to "0", the input of the gate _G16 changes from "1" to "0".
Since it becomes "0", the reset pulse of the final stage flip-flop Tn disappears. This is a so-called self-reset method. The time from time t ₉ to time tn is the counting time T _I of the first counter I for hysteresis control. tn~tn+1 after time T _I has passed
Since the temperature of the heated body 3 has decreased during the period , a pulse t _Po is generated, and upon detection of this pulse t _Po , the flip-flop R _S1 of the waveform shaping section c is set, and normal operation is resumed. Then, the thyristor 47 is triggered and the heater 48 starts to be energized.
By repeating these series of operations, the temperature swing ΔT _D of the heated object 3 shown in FIG. 6 is obtained. Note that when the hysteresis control changeover switch 10 is opened, the first counter I and the flip-flops RS ₃ and RS ₄ of the hysteresis control logic section H are reset by the gate G ₂₀ to enter the proportional control mode.

Next, the strong scale holding and the release operation shown in FIG. 7 will be explained. The resistance value of the volume 27 is set using the temperature setting knob 9 in order to obtain the scale temperature _TST as shown by the dotted line in FIG. Next, pull the knob 11 that selects holding the strong scale, and close the contacts 56' and 56'' of the changeover switch. Then, close the power switch 8 and start operation. At this time, the hysteresis The control changeover switch 10 is open, and the proportional control mode is set.The gate _G17 of the strong scale holding switching section J is set to "0", and the gate 18 is set to "1". This gate _G17 releases the reset of the second counter K for holding the strong scale. Furthermore, the reset of the flip-flop R _S5 of the storage section L is also released by the gate _G18 . Since the input of gate _G8 is also set to "0" by gate _G17 , the output of gate _G8 remains "1". As a result, the output Q of the T-type flip-flop T is not locked, and a proportional control mode is established in which the output to the thyristor 47 is continuously supplied. In other words, even if the hysteresis control switch 10 is closed and the hysteresis control mode is selected,
When the strong hold function is selected, the system automatically switches to proportional control mode. The waveform B in FIG. 7 shows this pattern. Further, since the first counter I is used as a part of the strong hold counter in addition to the counter for hysteresis control, the start of the counter is the same as the start of the counter for hysteresis control. That is, as shown in FIG. 28, there is a continuous pulse t _P from the neon lamp 30, and when the set temperature (strong scale temperature) is reached, the pulse t _P disappears, and the next pulse t _P3 is detected. Then, the first counter I starts frequency division from time _t9 . Then, between time tn and tn+1,
As shown in FIG. 28, the final stage flip-flop T _Io of the first counter I times out and Tn+1
The final stage flip-flop T _Io is reset at a time Δt _N before the time. When strong scale maintenance is set, the gate _G18 changes from "0" to "1", so the output Q of this final stage flip-flop T _Io
is the first stage flip-flop T _K1 of the second counter K
enter the input. As shown in FIG. 28, the output Q of the final stage flip-flop T _Io changes from "1" to "0".
When the edge falls to , the output Q of the first stage flip-flop T _K1 of the second counter K changes from "0" to "1", and the output of the first counter I for hysteresis control is carried up to the flip-flop T _K1 . . The carried output Q to the flip-flop T _K1 causes the gate _G24 to become "1" →
It becomes "0" and flip-flop R _S5 is set. Flip-flop R _S5 output is “1” →
By becoming "0", the set terminal of flip-flop R _S4 is held at "0" and flip-flop R
The output Q of _S4 is held at "1" so that the negative zero cross pulse ΔT is continuously supplied to the first counter I. In addition, the output of the flip-flop R _S5 becomes "0", and the input of the gate _G16 and the reset terminal R of the first counter I are all set to "0".
Prevents the reset signal from entering the counter.
The period from time t ₅ to the completion of the operation is Δt _A time, which is the same as the counting time in the hysteresis control mode. Since the negative zero-crossing pulse ΔT is continuously supplied to the input of the first stage flip-flop T _I1 , even when the counting progresses and the output Q of the final stage flip-flop T _Io changes from "0" to "1", the reset is not performed. The count does not start (it is locked by the flip-flop RS ₅ ) and the counting continues. Then, the final stage flip-flop TKn of the second counter K times out after the time _TK shown in FIG. 7 has elapsed, and the output Q changes from "0" to "1". Next, gate G ₁₂ is “0” →
During the positive voltage cycle of the power supply voltage V _AC which changes to "1", the AND output of the output Q of the final stage flip-flop T _Ko and the output of the gate G ₁₂ is applied to the input of the gate G ₂₇ , so that the gate G ₂₇ becomes "1". ” → falls to “0”, amplifier M operates, and thyristor 54 is triggered through pin 10. Then, the coil 56 is energized. The thyristor 54 is triggered only in the positive half cycle by the gate _G12 , and the excitation of the coil 56 opens the contacts 56' and 56'' of the strong scale holding switch. The temperature decreases to the value determined by the resistance value of G 17, and normal temperature adjustment is performed.Also, by opening the contact 56'', the strong scale holding switching section J returns to its original state, and the gate G ₁₇ is set to ``1''.
Since the gate _G18 becomes "0", the second counter K is reset by the gate _G17 and returns to the initial state.

Next, hysteresis control switch 1
0 is closed and the contact points 56' and 56'' of the strong scale holding switch are closed during operation in the hysteresis control mode, for example, at time t _D in FIG. 7. The operation will be explained. When the contacts 56' and 56'' of the strong scale holding switch are closed while the first counter I for hysteresis control is counting, the gate G ₁₇ changes to "1" as described above.
The second counter K is reset to "0", and the second counter K is reset and enters a count input standby state. Also the gate
The input of _G8 is unlocked, and the gate _G8 becomes "0".
→ becomes “1”, and immediately the T-type flip-flop T
The gate _G11 operates in a state determined by the output Q, and the thyristor 47 is triggered by the amplifier F. Therefore, the heater 48 is energized, and the temperature of the heated object starts to rise from time tD in FIG. Furthermore, the reset of the flip-flop R _S5 of the memory section L is also released by the gate _G18 . However, the first counter I continues counting. Then, when the final stage flip-flop T _Io of the first counter I times up,
It is carried to the first stage flip-flop _TK1 of the second counter K, and the output Q of the first stage flip-flop _TK1 changes from "0" to "1". The flip-flop R _S5 is set by the output Q of the first-stage flip-flop T _K1 , and the output of the flip-flop R _S5 becomes "1" →
It becomes "0". At this time, as explained in the above-mentioned hysteresis control mode, the first counter I is all reset, and the flip-flops R _S3 and R _S4 of the hysteresis control logic section H are also reset at the same time. When the temperature of the heated object 3 reaches the set temperature on the strong scale, the neon lamp 30
The pulse t _P from disappears and then again the pulse t _P3
28, the flip-flops R _S3 and R _S4 of the hysteresis control logic H are sequentially set by the operation described in connection with FIG. Due to this setting of flip-flop R _S4 , the Q of flip-flop R _R4 changes from "0" to "1".
Again, the positive zero cross pulse ΔT is detected by the first counter I.
It enters the input of the first-stage flip-flop T _I1 and performs frequency division operation. When the specified count is completed, the final stage flip-flop T _Ko of the second counter K times up, and the gates G ₂₇ and G ₁₂ trigger the thyristor 54 via the amplifier M, and the coil 56 opens the contacts 56' and 56''. This is the same operation as described above.As shown in Figure 7, during strong hold, the proportional control mode is set and the maximum amount of heat is applied.As explained above, the time _tD in Figure 7 On the way shown, contact 5 of the strong scale changeover switch
6', 56'', the effective strong scale holding time becomes the operating time _TK of the second counter K, which is shorter than when the switch is operated from the beginning by _ΔtA time. A resistor 66 and a capacitor 67 connected in parallel with the contact 56'' shown in Fig. 9 prevent the contact 56'' from chattering when the coil 56 opens the circuit, thereby preventing malfunction of the circuit due to the chatter operation of the contact 56''. do. In particular, several cycles of the AC power supply voltage V _AC are required to reliably maintain the open state of the contact 56''. Therefore, if the capacitor 67 is not provided, the strong scale holding switching unit will be activated as soon as the contact 56'' is opened. is activated, the first counter I and the second counter K are reset, and return to the counting state again, so there is a problem that the strong holding period is extended. By inserting this capacitor 67, stable operation is achieved.

Next, safety operations for a diode failure and a self-triggered state of the thyristor 47 will be described. In this state, regardless of the output of the temperature sensor 7,
Since the thyristor 47 becomes conductive and the heater 48 continues to be energized, the temperature of the heated object 3 continues to rise. Therefore, there is a risk of death from heatstroke to children, etc., or fire, and a safety function is required to prevent these accidents. FIG. 29 shows a time chart of the safety operation in the self-triggered state. 29th
In the figure, from time _t1 to time _t5 , the state is normal, that is, the temperature of the heated object 3 is low, and the neon lamp 30
An output is generated from pin 12 due to the pulse t _p from the thyristor 47, indicating that the thyristor 47 is normally triggered. From time _t5 to time _t7 , after the above state, the temperature of the heated body 3 reaches the set value, the pulse _tP disappears, and the thyristor 47 is turned off. During this pause, the input of the self-triggering amplifier P, that is, the input of the gate _G34 , is "0" because it is the AND of the output of the gate _G26 , the output of the voltage detection section N, and the output of the gate _G25 . It is. In FIG. 9, during the positive cycle of the power supply voltage V _AC from time t ₆ to _{t 7} , the gate G ₂₅ changes from "0" to "1" with a delay of Δt _N time.
The gate G ₂₆ changes from "0" to "1" with a delay of Δt _S time, and the voltage detection part N changes from "1" to "0" with a delay of Δt _C time from FIGS. 34 and 25 because the thyristor 47 is off. ”. This means determining the circuit of the voltage detection unit N (determining the time Δt _C ) and the self-trigger detection timing circuit O (determining the time Δt _S ) so that Δt _C <Δt _S. Therefore, the input of gate _G34 is "0" and the output is "1". Since the input of the amplifier P is "1", its output becomes "0" due to the circuit shown in FIG. 23, and no output is output to the thyristor 58. Next, a state in which the thyristor 47 has failed, such as a so-called diode failure or a self-trigger failure, is shown at times _t7 to _t11 . At this time, it is assumed that the pulse t _P from the neon lamp 30 is not emitted. That is, it is assumed that the temperature of the heated object is higher than the set value.
During the period from time t ₈ to _{t 9} when the power supply voltage V _AC enters the positive cycle, the thyristor 47 immediately conducts even without a gate signal, so the voltage detector N is in the off state and the output is "1". Hold. Moreover, the gate G ₂₅ becomes “0” after Δt _N beyond time t ₈ →
It becomes "1". Then, the gate _G26 of the detection timing circuit O changes from "0" to "1" with a delay of time Δt _S. Therefore, the output of the gate _G34 , which becomes the input of the amplifier P, is the output of the gate _G26 and the detection part N as described above.
Since this is an AND operation between the output of the gate _G25 and the output of the gate G25, "1" becomes "0" after a delay of Δt _S time. Therefore, the output of amplifier P becomes "0" with a delay of Δt _S time.
→ becomes “1” and the thyristor 58 is connected through pin 11.
is triggered to start heating the resistor 59. Since the thyristor 58 is turned off during the negative half-cycle period of the power supply voltage V _AC from time t ₉ to _{t 10} , the resistor 59 is not heated. The period in which the power supply voltage V _AC is in a positive cycle from time t ₁₀ to t ₁₁ is the period during which the power supply voltage V AC is in a positive cycle at time t ₈ .
The operation explained in t ₉ is performed, and the thyristor 58 is turned on with a delay of Δt _S from the time t ₁₀ to heat the resistor 59. Continuing this operation, the temperature of the resistor 59 rises and when it reaches the melting temperature of the temperature fuse 14,
Temperature fuse 14 melts and the power is cut off.

In addition, in FIGS. 8, 9, and 29, the resistor 5
9 and a temperature fuse 14, another circuit breaker, such as an electromagnetic circuit breaker having a set coil or a reset coil, may be used.

In addition, the temperature of the heated object 3 is adjusted using the temperature setting knob 9.
If the thyristor 47 self-trigger in a state lower than the temperature T _S set at , the self-trigger state is not immediately detected, and therefore the resistor 59 is not heated. The self-trigger state is detected and the resistor 59 is energized after the temperature of the heated object 3 becomes higher than the temperature set by the temperature setting knob 9 and the neon pulse t _P disappears. . In other words, to summarize the safety operation of the thyristor 47 in the self-triggered state, the presence or absence of the output of the temperature sensor 7 is compared with the output of the thyristor 47 that operates with this output, and even though there is no output of the temperature sensor 7, It detects the state in which the thyristor 47 is turned on and activates the safety function. In order to accurately operate this safety function, the timing Δt _S to detect the self-trigger
The relationship between Δt C and the operating time Δt _C of the voltage detector N that operates when the thyristor 47 is off is expressed as Δt _C <Δt _S
After the heated body 3 reaches the set temperature, it is determined whether the thyristor 47 is normal or not.

Next, the thyristor 47 that drives the heater 48
This section explains the safety and fail-safety of the trigger circuit. Equipment that heats the human body by touching it requires highly accurate temperature control and a high level of safety. In general, high-precision, multi-functional control requires a large number of constituent circuit parts and is complex. Therefore, there is a high level of insecurity against component failure, and high precision, multifunctionality, and fail-safety are contradictory. The electric circuit of the present invention includes:
In order to meet the requirements for high precision and multi-functionality, as well as fail-safe properties against component failure, the trigger circuit of the thyristor 47 is configured with an oscillation system of "0" and "1", and the capacitor 45 is charged and accumulated charge. The thyristor 47 is triggered only when First, the fail-safe nature of the trigger operation of the thyristor 47 will be explained based on FIG. 27. 27th
In the figure, during the negative half cycle period of the power supply voltage V _AC from time t ₁ to _{t 2} , the flip-flop RS ₁ of the waveform shaping section D remains in a reset state until the pulse t _{P 1} is generated from the neon lamp 30. Yes, the output Q of flip-flop _RS1 is "0" and the output is "1". Also, since the output Q of the T-type flip-flop T is "0" and the output is "1", the output of the gate _G9 is "0" and the gate _G10 is "1", and the amplifier E is inoperative and the capacitor 45 is not charged with electric charge. Further, since the output Q of the T-type flip-flop T is also "0", the gate _G11 becomes "1" and the amplifier F is also inoperative. Next, the pulse t _P1 is generated from the neon lamp 30, and the flip-flop RS ₁ is set, so the output of the flip-flop RS ₁ becomes "1".
→ becomes “0” and the output of gate _G10 is also “1” →
It becomes "0" and the capacitor 45 is charged. Next, flip-flop RS ₁ crosses zero, gate
By being reset at _G13 , the state of the T-type flip-flop T changes, and the output Q of the T-type flip-flop T changes from "0" to "1", and the output changes from "1" to "1".
As the gate _G11 changes from "1" to "0", the amplifier F discharges the accumulated charge in the capacitor 45, and the thyristor 47 is triggered.
Considering these series of operations, we get the following.

(1) In the inoperative (reset) state of the flip-flop RS ₁ receiving the pulse _tP , the trigger capacitor 45 is not charged and the flip-flop
Capacitor 45 is charged only when RS ₁ is in the operating (set) state.

(2) This flip-flop RS ₁ returns to the non-operating (reset) state again by the zero-cross pulse, and the output of the flip-flop RS ₁ , which is generated by the reset → set → reset of the flip-flop RS ₁ , changes from “1” to “0” → The AC waveform (oscillation waveform) that becomes "1" is frequency-divided by a T-type flip-flop T.

(3) The frequency-divided output Q of this T-type flip-flop T changes from "0" to "1", thereby discharging the energy accumulated in the capacitor 45.

The effects of these configurations (1), (2), and (3) are 2 to 3
This will be explained using two component failures as an example. First, if the flip-flop RS ₁ fails in an inoperative (reset) state, the output of the flip-flop RS ₁ will hold "1". Therefore, since the input of the gate _G9 maintains "1", the gate _G10 also becomes "1", and the capacitor 45 is not charged. Thyristor 47 is therefore inactive. Next, when the flip-flop _RS1 fails in the operating (set) state, the output of the flip-flop _RS1 becomes "1" and the output becomes "0". However, since the output of flip-flop _RS1 does not change alternately from "1" to "0" to "1", the T-type flip-flop T is
The input does not change, frequency division operation is no longer possible, and the system falls into a reset state. That is, the output Q is "0" and the output is "1". At this time, the amplifier E is activated by the gates _G9 and _G10 , and the capacitor 45 is charged, but the T-type flip-flop T
Since the output Q of is "0", the gate _G11 becomes "1", the amplifier F does not operate, and the thyristor 47 is not triggered. flip flop
When RS ₁ fails, the trigger output of thyristor 47 is not output. Next, when a failure occurs such that the T-type flip-flop T becomes inoperative (reset), the output Q of the T-type flip-flop T holds "0" and the output "1". At this time, the flip-flop _RS1 is alternately inverted in response to the pulse _tP , and only when the output of the flip-flop _RS1 drops to "0", the capacitor 45 is charged via the gates _G9 and _G10 , but the T-type flip-flop Since the output Q of T holds "0", the gate _G11 becomes "1" and the amplifier F is inoperative. Therefore, the thyristor 47 is not triggered and is safe. Then T
In the event of a failure in which the T-type flip-flop T becomes active (set), the output Q of the T-type flip-flop T holds "1" and the output "0". Since the output is "0" at this time, the gate G ₉ ,
From _G10 , the amplifier E continues to be turned on and charges the capacitor 45 via the resistor 44. Furthermore, if the output Q of the T-type flip-flop T remains "1", the discharge amplifier F also continues to be turned on from the gate _G11 . In this state, the current Ia flowing through the resistor 44
is not accumulated in the capacitor 45, but flows into the gate of the thyristor 47 via the discharge amplifier F. The current Ia has a value determined by the following formula.

Ia=V _CC -V _GK /R ₄₄ +Er+Fr However, V _CC is the voltage of Zener 25 in the control circuit, V
_GK is the voltage between the gate and cathode of the thyristor 47, _R44 is the value of the resistor 44, Er is the internal resistance of the charging amplifier E, and Fr is the internal resistance of the discharging amplifier F.
Generally, the non-triggering current I _G of the thyristor 47 (gate current that does not trigger under any conditions)
is a 2A type thyristor and I _GK =0.2mA. Therefore, by setting the value of the resistor 44 so that the relationship between Ia and I _GK is such that Ia<I _GK , even if the T-type flip-flop T fails in the operating (set) state, the current passing through the charging amplifier E can be reduced. are all discharge amplifier F
However, since the thyristor 47 is not triggered by this current Ia, safety is maintained.
Furthermore, the same applies to the gates G ₉ , G ₁₀ , G ₁₁ , the charging amplifier E, and the discharging amplifier F, ensuring safety. Next, regarding a failure in the hysteresis control logic section H, if this logic section fails to open (inoperative), the output of gate _G8 becomes "1" and everything returns to proportional control mode control. Furthermore, when a shot (operation) failure occurs, the output of the gate G ₈ becomes "0" and the gate G ₁₁ maintains "1", so that the discharge amplifier F is inoperative. Therefore, the triggering of thyristor 47 is stopped and safety is maintained. Also, the zero pulse generating section B is a clock generating section that becomes the time base of this control section, and if it fails, the time base changes from "0" to "1" to "0".
The signal that changes sequentially disappears. Therefore, as described above, since each logic gate holds "1" or "0", the trigger to thyristor 47 naturally disappears, and safety is maintained.

In short, the electric circuit of the present invention operates a series of control parts cyclically through a reset state, a set state, and a reset state, and uses this output to charge a capacitor (does not charge during charging) and discharges (does not charge during discharging). The thyristor 47 is triggered to achieve safety and fail-safety against component failure.

Next, the safety operation when the thyristor 47 causes a complete shot failure will be explained. Second
As shown in FIG. 8, the thyristor 47 is turned on across both waves of the power supply voltage V _AC . At this time, in the negative half cycle of the power supply voltage V _AC , the resistor 62 is energized by the diode 61 and heated. Thereafter, when the temperature of the resistor 62 rises and reaches the melting temperature of the temperature fuse 14, the temperature fuse 14 melts and the power is cut off.

Even if the electric circuit shown in FIG. 2 is operating normally, the heater 6 may be locally overheated, so the safety state in such a state will be explained. The heater 6 adopts the configuration shown in FIG. 4, and a thermofusible resin 50 is interposed between the layers of the heater wire 48 and the safety wire 49. When the heater 6 is partially blocked from dissipating heat for some reason, for example, the temperature locally increases. If the operation is continued in this state, the temperature will further rise, and finally the hot-melt resin 50 will melt, and the safety wire 49 and the heater wire 48 will come into contact with each other. Due to this contact, point A shown in FIG.
Heater wire 48 - contact part - safety wire 49 - resistor 55
A large current flows through the circuit at point -B, and the resistor 55 generates heat. The heat generated by the resistor 55 blows out the temperature fuse 14, stopping the power supply and maintaining safety.

_G28 shown in FIGS. 8 and 9 is an element for testing. In particular, when the control section 41 is incorporated as one IC on a single chip, it is used to check whether the IC is properly diffused and functions properly. It's pin and 7
It can be determined by h _FE between pins, I _CBO , etc. In other words, if the characteristics between the 6th and 7th pins are within the specified range, the quality of the IC 41 is guaranteed and it will operate normally.

Further, the lamp 13 in FIG. 2 has a thyristor 47
This is an indicator lamp that lights up only when the heater 48 is turned on, and notifies that the heater 48 is energized.

Figure 30 shows the strong scale holding function release coil 56.
and the configuration of the contacts 56' and 56''. When the knob 11 is pushed down as shown by the solid line in Fig. 30, the leaf spring 66 bends downward and is held at the bottom dead center by the coil spring 67. At this time, the contacts 56' and 56'' are open. Then, when the knob 11 is pulled up as shown by the broken line, the leaf spring 66
bends upward and is held at the top dead center by the coil spring 67 after passing through the inflection point. Even if the upward pulling force of the knob 11 is released in this state, the knob 11 remains raised upward. At this time, contacts 56', 5
6'' is closed.Then, thyristor 5 in FIG.
3 is triggered, the coil 56 is excited, the knob 11 is drawn downward, and the knob 11 is held at the bottom dead center position by the leaf spring 66 and the coil spring 67. At this time, the contacts 56' and 56'' open. When the knob 11 is pulled up and pushed down by an external force, that is, by a human hand, the knob 11 naturally descends to the bottom dead center, and then It is held at the position.In this case, the strong scale holding is manually canceled.

FIG. 31 shows another embodiment of the above-mentioned strong scale holding and its release method. In FIG. 31, coil 5
6, a relay having a set coil 561 and a reset coil 562 is used. Furthermore, instead of knob 11, push button knob 111
When the normally open contact 112 is used to set strong scale maintenance, when the knob 111 is pushed, the set coil 561 is excited by the contact 112. This excitation closes the contacts 56' and 56'' and enters strong scale operation. To release strong scale maintenance,
Thyristor 54 is triggered from pin 11 and reset by energizing reset coil 562, opening contacts 56' and 56''.

FIG. 32 is a modification of the circuit shown in FIG. 31, with push-on knob 113 for manual reset.
A reset coil 562 is externally excited by this normally open contact to perform a manual reset.

FIG. 33 shows an electrical circuit where the load is an inductive relay. Components having the same function as those in the circuit of FIG. 2 are given the same symbols. In FIG. 33, the thyristor 47 operates a transformer relay 69 having two windings 691 and 692, and its normally open contact 70 controls the energization of the heater 6. The voltage of the secondary winding 692 of the transformer relay 69 is full-wave rectified by the full-wave diode bridge 71, and when the thyristor 47 is triggered, a short circuit current flows through the secondary winding 692, and the current of the primary winding 691 The contact point 70 is closed.

FIG. 34 shows voltage and current waveforms at various parts of the electric circuit shown in FIG. 33. Figure 34a shows the secondary winding 6
The current flowing through 92 lags behind the voltage waveform by θ degrees. This angle θ is the R/L of the resistance R of the remote control relay serving as the load and the inductance L.
is the delay angle (extinguishing angle of the thyristor) determined by FIG. 34b shows an example in which the trigger pulse of the thyristor 47 (output from pin 12) is generated at the point in time when the voltage waveform crosses zero voltage. At this time, the extinction angle of the thyristor 47 (the point at which the current rises and then falls to zero) becomes θ ₁ , and the next cycle begins. That is, when a trigger pulse is applied at time _t1 , current flows _{until t2} +θ1. Also, time t ₂
Even if a trigger pulse is applied at , the pulse has disappeared by _θ1 , so the thyristor 47 is not turned on during the period from time _t2 to time _t3 . In this way, the thyristor 4 periodically at the point where the voltage crosses zero voltage
Even if 7 trigger pulses are generated, the thyristor 47 is turned on in half-wave conduction every cycle as shown by hatching. Therefore, the contact 70 of the transformer relay 69 generates chatter, and normal operation cannot be expected. In order to solve this drawback, the third
As shown in FIG. 4c, the phase of the trigger pulse generated by the thyristor 47 is forcibly delayed by θ determined by the load for triggering. In the case of FIG. 34c, triggering can be performed reliably over all waves, and the transformer relay 69 operates smoothly. Figure 34d is
In order to delay the trigger pulse by this angle θ, this is an example in which the input voltage at pin 16 in FIG. 33 is delayed by a capacitor or the like, and the control circuit 41 is activated.
In FIG. 33, a phase delay section 75 including a resistor 76 and a capacitor 77 plays this role.
In addition, the 16th pin is connected to the phase delay unit 75 via the resistor 42.
connected to.

The control circuit 41 of this electric circuit detects the temperature in half cycles of the power supply voltage V _AC as described above.
Since the trigger pulse for the 2-bit thyristor 47 is obtained by the pulse t _P generated in this half cycle, the thyristor 47 always becomes a full-wave trigger and never a half-wave trigger. However, in the case of control that detects the temperature in the positive half cycle and turns on the thyristor only in the negative half cycle, then detects the temperature in the negative half cycle and turns on the thyristor only in the positive half cycle, the following problem occurs. There is a possibility that this may occur. That is, the neon lamp 30 of the temperature detection section 29
With respect to the discharge voltage V _BO in the positive half cycle, V
_BOP and V _BON in the negative half cycle are V _BOP = V _B
There is no problem when it is _ON , but when V _BOP ≠ V _BON , when the temperature of the heated object 3 becomes close to the set temperature, the neon lamp 30 breaks down only in the positive or negative half cycle of the power supply voltage V _AC . There is. In such a case, the thyristor 47 triggers only the positive or negative half cycle of the power supply voltage V _AC , so if the load is a relay, chatter will occur and the relay contacts will weld. Furthermore, if the load is an induction motor or the like, only a half-wave current flows, so the motor does not rotate, and there is also the problem that the motor may burn out due to the direct current. However, the control circuit 41 of this electric circuit
As mentioned above, since it is a circuit that generates a 2-bit trigger pulse, it is necessarily a full-wave trigger and an alternating current necessarily flows, so it is suitable for inductive loads.

Further, in FIG. 33, a resistor 79 of the temperature setting section 26 is inserted to add temperature hysteresis when operating in the hysteresis control mode. As explained in Fig. 2, Fig. 9, Fig. 28, etc., the first
The counter _I starts counting when the pulse t _P is continuously triggered as shown in FIG. This is when _P occurs. In FIG. 28, this period is shown as T _D.
The resistor 79 in FIG. 33 determines this period T _D , and its operation is to generate a pulse t _P when the temperature of the heated object 3 drops from the set off temperature T _OFF to the Δt _OFF temperature, and to control the temperature. This gives the differential of More specifically, when the heated object 3 is being heated by the heater 48, the contacts of the transformer relay 69 are closed. Therefore resistance 7
9 is connected in parallel with the resistor 8 and the volume 27, and this parallel resistor R _Y is as follows.

R _Y =(R ₂₈ +R ₂₇ )×R ₇₉ /R ₂₈
+R ₂₇ +R ₇₉ However, R ₇₆ is ignored.

When the temperature T _OFF set by R _Y (less than R ₂₇ + R ₂₈ ) is reached, the thyristor 47 is turned off, the transformer relay 69 is also turned off, and the heater 48
Power to the unit will be cut off. At this time, the resistor 79 is connected from the volume 27 side to the interlayer impedance _Z7 side of the windings 36 and 37 of the sensor 7 (via the heater 48). After that, when the temperature of the heated body 3 decreases and Δt _OFF decreases, the interlayer impedance
_Z7 increases, causing the neon lamp 30 to discharge,
The neon pulse t _P occurs again. Decreasing the value of resistor 79 will increase Δt _OFF , and increasing the value will decrease Δt _OFF . Therefore, in the configuration shown in FIG. 33, the off period Δt _A of the thyristor 47 in the hysteresis control mode is determined by the T _D time determined by the temperature differential and the counting time of the first counter I for hysteresis control. It is the sum total of T _I time. The features of this method are as follows. (1) When the heat retention of the heated object 3 is good, heat dissipation is poor, so the temperature of the heated object 3 decreases slowly, and Δt _A in Fig. 6 is essentially the temperature differential Δt _OFF . It is determined. That is, the time T _D of Δt _OFF >> the time T _I of the first counter I. (2) When the heat dissipation of the heated object 3 is good, the temperature of the heated object 3 decreases rapidly, and Δt _A in FIG. 6 is substantially determined by the time of the first counter I. That is, the time T _D of Δt _OFF << the time T _I of the first counter I. In particular, when the heater 48 is turned on and off using a contact system such as a relay, the relay does not operate during the lock time T _I of the first counter I, so that the life of the contact can be extended, contributing to an improvement in life. It also helps prevent power failures caused by frequent turning on and off.

Furthermore, by making the resistor 79 adjustable in FIG. 33, the temperature swing width ΔT _D can be selected according to the environment in which the heated object 3 is installed and according to the user's preference. Although not shown, the temperature swing width ΔT _D can also be changed by changing the number of flip-flop stages of the first counter I in FIG.

Next, another embodiment that achieves the same effect as described above will be described. This method uses 30 neon lamps
In this method, the number of pulses t _P obtained from the first counter I is counted. That is, when the temperature of the temperature sensor 7 is low, the pulse t _P
Since Z ₇ is large, the neon lamp 30 will trigger at an early phase of the supply voltage V _AC and generate several pulses in a half cycle of the supply voltage V _AC . When the temperature rises and approaches the set temperature, only one pulse t _P is generated at a slow phase of half a cycle of the power supply voltage V _AC . A similar effect can be obtained by counting this pulse t _P with a counter and stopping the power supply to the heater 48 during this counting period.

The various hysteresis control methods described above depend on the slope at which the heated object 3 descends from the set temperature T _OFF , that is, the state of heat dissipation.
This is a temperature-dependent hysteresis control method in which the off-period of the switch changes.

Next, an embodiment in which the off period of the heater 48 is determined only by time will be described. In Figure 9, the flip-flop of the hysteresis control logic H
Delete RS ₄ and convert the input of gate G ₂₁ connected to the output Q of flip-flop RS ₄ to a flip-flop.
When connected to the output Q of RS ₃ , the T _D time is eliminated and it becomes possible to start the first counter I immediately after the disappearance of the pulse t _P. In this system, compared to the conventional temperature control method that obtains a differential based on temperature, the heater 48 is always turned off for the time set by timer T _I , which prevents power failure due to frequent on/off and low power capacity. Relay 6 at home
9. Problems caused by chatter are resolved. That is, in the circuit of FIG. 33, when the temperature differential Δt _OFF is obtained only by the resistor 79, when the value of the resistor 79 is increased, the transformer relay 6
9 is turned on and the heater 48 is energized, the power supply voltage V _AC drops, and this voltage drop turns off the neon lamp 30 that has been lit up until now. Since the trigger of the thyristor 47 is stopped by this turning off, the remote control relay 69 is also turned off, and the power supply to the heater 48 is stopped. Then, when the heater 48 is turned off, the power supply voltage V _AC is restored to its original value, so the neon lamp 30 is turned on again, and the thyristor 47 activates the relay 69. In this way, there is a risk of inducing a chattering phenomenon in the relay 69. Especially when the power capacity of the heater 48 is large, this tendency becomes an unavoidable problem. Because of this problem, the value of the resistor R ₇₉ is effectively reduced to reduce the temperature differential Δt _OFF.
must be set extremely large. In this electric circuit, the heater 48 is controlled by a simple first timer I.
This lock also has the advantage of overcoming the above drawbacks.

Next, in the circuit shown in FIG. 33, safe operation in the event of component failure will be explained. If the contacts 70 of the transformer relay 69 cause a welding accident, the heater 6
is continuously energized and is dangerous. In this state, first, when the temperature of the heated object 3 reaches the set temperature, the pulse t _P of the neon lamp 30 disappears.
The trigger pulse of thyristor 47 from pin 12 disappears. Therefore, the thyristor 47 is turned off, so
The thyristor 58 is triggered by the resistor 47, and the resistor 59 generates heat. Thereafter, the temperature of the resistor 59 rises and the temperature fuse 14 is blown to shut off the power supply, so safety can be ensured. In addition, thyristor 47
When a shortcut accident occurs, transformer relay 69
continues to operate, the contact 70 causes the heater 6 to
is heated continuously and is dangerous. At this time, the voltage of the thyristor 47 is detected by the resistor 57, the self-trigger circuit of the control section 41 is activated, and a trigger pulse for the thyristor 58 is obtained from the 11th pin. Then, the thyristor 58 turns on and the resistor 59 generates heat.
It is safe because the power is stopped by blowing the temperature fuse 14. Furthermore, when the heater 6 is locally overheated, the heater wire 48 and the safety wire 49 come into contact with each other, based on the same principle as explained in FIG.
1 and 61 are energized by diodes 61 and 68. As a result, the resistor 51 or 61 generates heat, the temperature fuse 78 melts, and the power supply to the heater 6 is stopped to ensure safety.

Next, another embodiment in which the load is inductive will be described. FIG. 35 shows an example of the circuit. Third
Components that perform the same functions as those in the circuit shown in FIG. 33 are given the same symbols. The difference between FIG. 33 and FIG. 35 is that the thyristor 47 is triggered by a direct current using a transistor 80. FIG. 36 shows operating waveforms of each part of the circuit shown in FIG. 35, and the operation will be explained based on FIG. 36. When the pulse t _P is generated during the negative cycle period of the power supply voltage V _AC , the outputs from the 15th pin and the 12th pin of the control section 41 have the operating waveforms shown in FIG. 36, as already described in detail.
Therefore, in the circuits shown in FIGS. 2 and 33, the output from pin 12 was used as the trigger pulse for the thyristor 47, but in the circuit shown in FIG. Alternatively, the terminal voltage of the discharged capacitor 45 ( _C45 terminal voltage in FIG. 36) is detected by the emitter follower type transistor 80. And the resistors 81 and 82 when the "terminal voltage of C ₄₅ " in Figure 36 is generated.
At a voltage of , the thyristor 47 is triggered with a direct current. As a result, the operating waveform of the transformer relay 69 becomes as shown in FIG. 36, and the relay 69 can operate reliably regardless of the R/L value. Then, when the temperature of the heated body 3 rises and the neon pulse t _P disappears, the terminal voltage of the capacitor 45 "terminal voltage of C ₄₅ " decreases, and at this point the thyristor The DC trigger 47 stops, the thyristor 47 turns off at time _t8 in FIG. 36, and the transformer relay 69 becomes inactive.

As already described in detail, the circuit shown in FIG. 35 is characterized by being a so-called fail-safe circuit in which the terminal voltage of the capacitor 45 is generated only when all the components are normal. Since this voltage is amplified by an emitter follower type amplifier including the transistor 80 and provides a DC trigger to the thyristor 47, it is possible to reliably operate an inductive load while maintaining a fail-safe system. Other operations are exactly the same as the circuit shown in Figure 33, so
The explanation will be omitted.

Next, a so-called one-wire electric circuit that integrates a heater and a temperature sensor will be described. Third
Figure 7 shows the circuit. Figure 2, Figure 33, Figure 3
In the circuits shown in FIG. 5, the temperature sensor 7 and the heater 6 are arranged in separate lines, that is, two lines. The circuit in FIG. 37 consists of a heater 6 and a temperature sensor 7.
This is an example of a one-wire type in which the so-called heater 6 also serves as a temperature sensor, and the interlayer material 50 between the heater wire 48 and the safety wire 49 is a temperature-sensitive material made of an organic semiconductor having the characteristics shown in FIG. It is configured. 37th
The operation of the circuit shown in the figure is exactly the same as the two-wire circuit shown in _FIG . , the temperature is controlled by the pulses t _P obtained. Although other operations will be omitted, the one-wire circuit shown in FIG. 37 has the advantage of being simpler in configuration than the two-wire circuit.

In addition, in the above-mentioned embodiment, an example is shown in which a thyristor or an electromagnetic relay is used as a power control element.
Although an SCR was used as the thyristor, other devices such as a triax may also be used.

Based on the above configuration, the present invention has the following effects.

(1) Logic compares the output of the temperature detection circuit and the terminal voltage of the power control element, and stops power supply to the load when the power control element conducts even though the output of the temperature detection circuit is an off signal. It detects secondary phenomena caused by short failures in power control elements.For example, unlike detecting failures due to parts becoming hot due to this failure, it detects the failure itself. Therefore, it is possible to prevent the various parts from heating up, resulting in higher safety.

(2) In particular, self-trigger failures in SCRs used as power control devices cannot be detected using conventional waveform identification methods because the half-wave current that is almost the same as when the SCR is in normal operation flows through the load. If this method is used, it can be detected reliably.

[Brief explanation of the drawing]

Fig. 1 is an external view of an electric blanket or electric bed sheet, which is one of the fields of application of the present invention, Fig. 2 is a circuit diagram showing an entire embodiment of the temperature control circuit of the present invention used therein, and Fig. 3 Figure 4 is a configuration diagram of the temperature sensor, Figure 4 is a configuration diagram of the heater, Figure 5 is a temperature impedance characteristic diagram of the temperature sensor, Figure 6 is a characteristic diagram showing proportional control mode and hysteresis control mode, and Figure 7 is a characteristic diagram showing the proportional control mode and hysteresis control mode. A characteristic diagram showing the strong scale holding mode, Figure 8 is a circuit diagram showing the control circuit as a block diagram,
FIG. 9 is a circuit diagram showing the logic circuits in each diagram of the control circuit, FIG. 10 is a circuit diagram showing one embodiment of the reset voltage detection circuit, and FIG. 11 is a circuit diagram showing another embodiment of the reset voltage detection circuit. A circuit diagram, FIGS. 12A and 12B are waveform diagrams of its operation, and FIG. 13 is a circuit diagram showing yet another embodiment of the reset voltage detection circuit.
Fig. 14 is a circuit diagram showing one embodiment of the zero voltage detection circuit, Fig. 15 is a waveform diagram of its operation, Fig. 16 is a circuit diagram showing one embodiment of the waveform shaping circuit, and Fig. 17 is the waveform shaping circuit. Circuit diagram showing another embodiment of
Figure 8 is a circuit diagram showing an example of a pulse detection circuit.
Fig. 19 is a waveform diagram of its operation, Fig. 20 is a circuit diagram showing an embodiment of the charging amplifier, Fig. 21 is a circuit diagram showing an embodiment of the hysteresis control switching circuit, and Fig. 22 is a strong scale maintenance switching circuit. A circuit diagram showing an embodiment of the circuit, FIG. 23 is a circuit diagram showing an embodiment of the self-trigger output amplifier, and FIG. 24 is a circuit diagram showing an embodiment of the voltage detection circuit and detection timing circuit of the self-trigger detection section. Figure 25 is a waveform diagram of its operation, Figure 26 is a circuit diagram showing an example of the intermediate output circuit of the first counter, Figure 27 is a waveform diagram of proportional control mode operation, and Figure 28 is hysteresis control. Waveform diagram of mode operation, Figure 29 is a waveform diagram of self-trigger detection operation, Figure 30 is a sectional view of the switch section for holding and releasing strong scale, and Figure 31 is a circuit diagram for holding and releasing strong scale. Circuit diagram showing one embodiment, No. 32
The figure is a circuit diagram showing another embodiment of the circuit for holding and releasing the strong scale, Fig. 33 is a circuit diagram showing the whole of another embodiment in which the heater current is controlled by a relay, and Fig. 34 is a circuit diagram showing another embodiment of the circuit for holding and releasing the strong scale. A waveform diagram of its operation, Figure 35 is a circuit diagram showing the whole of another embodiment in which the heater current is controlled by a relay, Figure 36 is a waveform diagram of its operation, and Figure 37 shows the relationship between the heater and the temperature sensor. FIG. 2 is a circuit diagram showing the entire one-wire embodiment in which the two are integrated. 1... Power plug, 2... Controller box, 3... Heated object, 6... Heater (heat generation load), 7... Temperature sensor, 8... Power switch,
9... Temperature setting knob, 10... Hysteresis control switch, 11... Strong scale maintenance switch, 14... Temperature fuse (power circuit breaker), 15... Noise hilter section, 19... Control power supply V _CC Obtaining circuit, 26...Temperature setting circuit, 2
7...Temperature control volume, 28...Limiting resistance,
29...Temperature detection circuit, 30...Neon lamp (pulse trigger element), 33...Pulse transformer,
41...Control circuit (IC), 43...CR for trigger
Circuit, 45... Capacitor, 47... Thyristor, 54... Thyristor, 55... Resistor, 56...
... Coil, 56', 56'' ... Contact, 58 ... Thyristor, 59 ... Resistor, 61 ... Diode, 6
2... Resistor, A... Reset section, B... Zero pulse generation section, C... Waveform shaping section, D... 2-bit frequency dividing section, E... Charging amplifier section, F... Discharging amplifier section, G... ...Hysteresis control switching section, H
...Hysteresis control logic section, I...
...First counter, J... Strong scale retention switching section, K...
...second counter, L...memory device for holding strong scale,
M... Output amplifier for canceling strong scale holding.

Claims (1)

[Claims] 1 A load such as a heater, a thyristor that directly or indirectly supplies power to this load, a temperature sensor, and outputs an on signal when the temperature detected by this temperature sensor is lower than the set temperature, and an off signal when it is higher. a temperature detection circuit, a safety circuit that stops power supply to the load, a zero pulse generation circuit that outputs in response to the positive phase and negative phase of the alternating current, and If the output is on, it becomes low until the next normal phase, and if it is off, it remains high.The waveform shaping circuit maintains the high state, and the output of this waveform shaping circuit and the output of the zero pulse generation circuit allow the output to be output only when the alternating current is in positive phase. a hysteresis control circuit that becomes high; a control circuit that triggers a thyristor according to the output state of the waveform shaping circuit; and a control circuit that becomes high when the thyristor is on and low when it is off; It includes a terminal voltage detection circuit with a short output time, and a timing detection circuit that emits a signal for a period shorter than the output time of the terminal voltage detection circuit, and the output from the waveform shaping circuit, the output from the terminal voltage detection circuit, and the A temperature control device comprising an output of a hysteresis control circuit and a failure detection circuit that outputs an output when all outputs of the timing detection circuit are high and drives the safety circuit.