JPH079612B2 - Temperature control device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a temperature control device for controlling energization of a heating element such as an electric kotatsu used in a general household, and particularly to improvement of a temperature detection mechanism thereof. .

(B) Prior Art Generally, as a temperature control device used for household electric kotatsu, the inventions described in, for example, JP-A-58-158722 and JP-A-58-165166 are known. Has been.

In the former, the amount of air blown to the semiconductor heater is controlled by controlling the energization of a motor that drives a fan that is a blowing means, and the amount of heat blown to the semiconductor heater is indirectly controlled by the amount of air blown. . In the latter case, the heater is energized by ON / OFF control.

Further, those shown in FIGS. 8 and 9 are also well known.

The one shown in FIG. 8 is a circuit diagram of an electronically controlled kotatsu. For example, when "low" is set in the controller (50), the phase control of the triac (24) in the controller (50) is performed and the energization corresponding to the setting is performed. Heater (51) at a rate (small W)
To control. FIG. 9 is a circuit diagram of a so-called microcomputer-controlled semiconductor warm air kotatsu, which shows a semiconductor heater (52).
The micro computer (53) is used to control the energization rate of each of the blower motor (54) and the semiconductor heater (52), and the wattage of the semiconductor heater (52) itself is mixed with the kotatsu. It controls the internal temperature. That is, in FIG. 9, a bridge circuit is constituted by the variable resistor (55) for temperature setting, the resistors (56) and (57), and the thermistor (58) provided in the kotatsu, which operates as a temperature detecting means. The output signal is input to the A / D input terminal of the microcomputer (53). (59)
Is a thermistor for detecting room temperature and constitutes another bridge circuit. The temperature in the kotatsu is judged by the output signal, that is, the A / D input, and when the temperature in the kotatsu is considerably lower than the set temperature, the microcomputer (5
Trigger the triac (61) through transistor (60) from D ₂ outputs with a 100% supplied to the motor (54) 3), via a transistor (62) by D ₀ output triac (63) Trigger and semiconductor heater (52)
Energize 100%. After this, when the temperature inside the kotatsu reaches the set temperature, the duty ratio of the semiconductor heater (52) is reduced to 50%. When the temperature inside the kotatsu reaches the set temperature, the duty factor of the motor (54) becomes 50% and the semiconductor heater (52)
The temperature is controlled by reducing the current-carrying rate of each to 10%. Therefore, it is possible to control the temperature of kotatsu, which has a short time until reaching the set temperature (hereinafter referred to as rising) and has a very small variation range in the kotatsu after reaching the set temperature (hereinafter referred to as stable).

(C) Problems to be solved by the invention However, the lamp heater cannot be used for those whose temperature is controlled by the air volume, or the heater is turned on and off.
When performing temperature control with the temperature inside the kotatsu stabilized, a temperature range (differential) between ON and OFF occurs, and when the heater is of the lamp type, the lamp goes off when the heater is OFF. This gives the user a feeling of lack of visual warmth.

Further, the structure shown in FIG. 8 has a problem that it takes time to reach the target temperature (set temperature) at the time of rising.

Further, in the case shown in FIG. 9, since the semiconductor heater is used, there is no radiant heat, and the sensation of warmth at the beginning of energization is inferior to that of the lamp heater. Therefore, when the lamp heater is controlled by this circuit, The phase control ratio is 100%, 5
Since it is 0% and 10%, there is light and dark in the lamp and NO
There was a problem that the temperature range between the time of turning off and the time of turning off increased.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a temperature control device in which a lamp heater is used for a heating element, the rise time is short, and the temperature range around the heating element can be extremely small when stable. Is.

(D) Means for Solving the Problems The structure of the present invention includes a heating element and a temperature sensing means for detecting a change in ambient temperature due to the heating element, and the heating element responds to a signal from the temperature sensing means. In the temperature control device for controlling the energization of the capacitor, the capacitor that is repeatedly charged and discharged at a constant cycle, and the charging voltage of the capacitor at the time when a predetermined time has elapsed after the start of charging the capacitor and the temperature sensing means. A determination means for comparing the voltage of the signal with the determination means, and the predetermined time for the determination is determined when the charging voltage becomes equal to or smaller than the voltage of the signal of the temperature sensing means once after the predetermined time has elapsed. And a time change means for changing the predetermined time to a shorter predetermined time, and electrically connecting a duty ratio control means for controlling the duty ratio of the heating element by the output signal from the determination means to the heating element. Is provided by Temperature control device.

(E) Action Since the present invention is configured as described above, the charging voltage of the capacitor and the signal voltage of the temperature sensing means are compared by the determination means after a predetermined time has elapsed, and the output signal of the determination means is determined by the predetermined value. If a high potential level is reached over time, the duty ratio control means energizes the heating element at about 100%, and conversely if it is a low potential level, energizes the heating element at the timing when the high potential level is reached. It is done by control. Then, after a predetermined time once, when the charging voltage becomes equal to or smaller than the signal voltage of the temperature sensing means, the time changing means changes the predetermined time to a predetermined time shorter than the predetermined time, and a hysteresis is set at the time of judgment. It acts to prevent the provided lamp heater from becoming bright or dark.

(F) Embodiments Embodiments of the present invention will be described in detail below with reference to the drawings, but the present invention is not limited to the following embodiments.

In FIG. 1, (1) is a zero-cross pulse generation circuit, which outputs a pulse signal (b) when the voltage (a) of the AC power supply (2) becomes 0V. (3) is a delay circuit, which is electrically connected to the zero-cross pulse generating means (1), delays the pulse signal (a) for a predetermined time, and then outputs the pulse signal (c). (4) is a time changing means, which is connected to the delay circuit (3) and is connected to control the time width of the delay signal (d) of the timer circuit (4a) and the timer circuit (4a) ( 4b) and its capacitors (4b)
It is composed of a transistor (4c) and a resistor (4d) (4e) for controlling the charging time of. The one shown in FIG. 1B uses a timer IC 555 in the timer circuit (4a), and the charging time of the capacitor (4b) connected to the threshold terminal is set to the collectors of the transistor (4c) and the transistor (4c). It is variable by the connected resistance (4e) and the resistance (4d) connected in parallel to the series circuit of the transistor (4c) and the resistance (4e). That is, when the transistor (4c) is turned on, the resistor (4d) and the resistor (4e) are connected in parallel, the charging time becomes shorter than when the transistor (4c) is turned off, and the output of the timer circuit (4a) is output. Delay signal (d)
Becomes shorter. (5) is a capacitor, and the transistor (6) is connected in parallel. That is, the collector of the transistor (6) is at one end of the capacitor (5),
The emitters are connected to the other ends, and the other ends are connected to the ground. A variable resistor (7) is connected to the DC power supply line at one end of the capacitor (5). The variable resistor (7) is for temperature adjustment.
(8) is a temperature sensing means, for example, a thermistor having a negative characteristic,
Connected in series with the resistor (9), the capacitor (5) and the series circuit of the variable resistor (7) form a bridge circuit. (10) is a comparison circuit, the + input end of which is the connection point of the capacitor (5) and the variable resistor (7), and the − input end is the connection point of the temperature sensing means (8) and the resistor (9). It is connected. (11) is a judging means, for example, a JK flip-flop, whose J input terminal is the output terminal of the comparator circuit (10), and whose clock (hereinafter referred to as CLK) input terminal is the output of the time changing means (4). Connected to each end. Furthermore, the resistance (1
2) and light emitting diode (13) in series circuit and resistance (1
4) and the series circuit of the light emitting diode (15) are connected respectively. The light emitting diode (13) emits light indicating that the temperature is low, and the light emitting diode (15) emits light indicating that the temperature is proper. (16) is a duty ratio control means, and two AND circuits (17) (18), diodes (19) (20) connected to their respective output terminals, and cathodes of the respective diodes (19) (20). Is composed of a transistor (21) connected to the base and a semiconductor control means (24) connected in series to a heating element (23) such as a lamp heater. A triac is suitable as the semiconductor control means (24). A series circuit of the heating element (23) and the semiconductor control means (24) is connected in parallel to the AC power source (2).

Further, one input terminal of the AND circuit (17) has a determination means (11).
Is connected to the Q output terminal and the other input terminal is connected to the output terminal of the one-shot multivibrator (25). Also AN
One input end of the D circuit (18) is connected to the output end of the judging means (11), and the other input end is connected to the output end of the one-shot multivibrator (26). The input end of the one-shot multivibrator (25) is connected to the output end of the zero-cross pulse generation circuit (1), and the input end of the one-shot multivibrator (26) is connected to the output end of the comparison circuit (10).

Next, the operation of this embodiment will be described with reference to FIGS.

The capacitor (5) is repeatedly charged and discharged at a constant cycle by the pulse signal (c) output from the delay circuit (3). That is, the transistor (6) is OF
Charging is performed through the variable resistor (7) when F, and discharging is performed when the transistor (8) is ON by the pulse signal (c). The charging voltage of the capacitor (5) during this charging / discharging is (g).

Now, it is assumed that the ambient temperature of the heating element (23) is low.

The comparison circuit (10) compares the charging voltage (g) with the voltage (f) divided by the temperature sensing means (8) and the resistor (9), and if the respective voltages are the same, the high potential level. Output signal (h). If the output signal (h) is at the high potential level when a predetermined time has elapsed after the start of charging the capacitor (5), the output signal (i) is output from the Q output terminal of the judging means (11). The output signal (i) causes the light emitting diode (24) to emit light, indicating that the temperature is low. Further, the output signal (i) is input to the AND circuit (17), and the one-shot multivibrator (25) is triggered by the trailing edge of the pulse signal (b) from the zero-cross pulse generation circuit (1) and outputs. The AND circuit (17) outputs the output signal (j) for the pulse width time of the pulse signal (e) to turn on the transistor (21). When the transistor (21) is turned on, the semiconductor control means (24) is triggered to energize the heating element (23). The timing at which the semiconductor control means (24) is triggered depends on the one-shot pulse signal (e). Therefore, as can be seen from FIG.
100% energization rate (the energization waveform is m and energization is shown by the solid line)
Becomes In the above state, the AND circuit (18)
Since the output signal (h) from the judging means (11) input to one of the input terminals is "L", the output does not become "H".

After this, when the ambient temperature rises, as shown in FIG. 2B,
The output signal (h) of the comparison circuit (10) becomes a high potential level after a lapse of a predetermined time after the start of charging. That is, as the temperature rises (suitable temperature), the resistance value of the temperature sensing means (8) decreases, and therefore the voltage (f) applied to the-input terminal of the comparison circuit (10) rises, It takes time until the charging voltages (g) match. The determination means (11) outputs the output signal (k) from the output end because the output signal (h) input to the J input end is at the low potential level when a predetermined time has elapsed. At this time, the output signal (i) becomes "L". Therefore, the transistor (4c) of the time changing means (4) is turned on and the resistance (4c)
d) and resistor (4e) are connected in parallel to form a capacitor (4b)
The charging time to the battery becomes short (the charging voltage waveform of the capacitor (4b) is shown as (n) in FIG. 2B). As a result, the time width of the delay signal (d) of the time changing means (4) becomes short. Here, the energization of the heating element (23) is 100% until 100% immediately before the energization by the phase control depending on the intersection angle between the charging voltage (g) and the voltage (f) from the above 100% energization. Since what has been energized changes to approximately 50% of the energization, the ambient temperature of the heating element (23) drops sharply as indicated by the dotted line α in FIG. 3A, and then the delayed signal (d) If you do not keep the time width of
It becomes a state of 0% energization, and the energized state of 100% and 50% is repeated. However, in this embodiment, by shortening the time width of the delay signal (d), even when the time when the charging voltage (g) and the voltage (f) match becomes earlier, a time point when a predetermined time elapses from the start of charging. Therefore, they do not match, and the energization is controlled by the phase control without switching to 100% energization.

This point will be described in detail with reference to FIG.

At the time of reading the level comparison result between the charging voltage (g) of the capacitor (5) and the voltage (f) corresponding to the resistance change of the temperature sensing means (8), a predetermined time ( It is set at a time point (hereinafter referred to as point I) after a lapse of time t ₁ . Since the temperature of the temperature sensing means (8) is low at the current-carrying place, the result of level comparison between the charging voltage (g) and the voltage (f) at point I is (g)> (f). Energize (23) about 100% (eg about 500w). The ambient temperature rises rapidly due to the energization of 500 w, and the voltage (f) rises accordingly, and eventually (g) = (f) at point I. At this point, detect point I
Move to point II. That is, it is changed to read the level comparison result of the charging voltage (g) and the voltage (f) when the time t ₂ has elapsed after the start of charging the capacitor (5). When the voltage (f) reaches the charging voltage (g), the detection point moves to point II, so (g) <(f) and the heating element (2
The energization to 3) becomes the intersection angle (250w) between the charging voltage (g) and the voltage (f), and the phase control is performed. At this point, the ambient temperature is once lowered, the temperature of the temperature sensing means (8) is also lowered, and the voltage (f) is lowered to the voltage (f '). However, even at this point, since the detection point is the II point, the charging voltage (g) is lower than the voltage (f ') ((g) <
(F ')), the state of phase control is continued. Therefore
It does not become 100% energized, and the number of w increases in inverse proportion to the decrease from voltage (f) to voltage (f '), and at voltage (f')
It is energized for 350w, and power is linearly supplied in proportion to temperature. By the way, considering the case where the detection point is fixed to point I, about 100% energization and about 50% energization alternate with the change of ambient temperature, that is, the movement of voltage (f), with the point I as the boundary. When a lamp heater is used for the heating element (23), brightening and darkening are repeated.

The above operation will be described with reference to FIGS. 1A and 2B.
The output signal (k) turns on the light emitting diode (15) to display an appropriate temperature, and the output signal (k) is input to one input terminal of the AND circuit (18) and input to the other input terminal. An output signal (j) is output from the AND circuit by being ANDed with the one-shot pulse signal (1) output by the one-shot multivibrator (26) triggered by the leading edge of the signal (h). Then, as in the case of the above low temperature, the transistor (21) is turned on by the output signal (j).
Then, at this timing, the semiconductor control means (24) is phase-controlled to control the energization of the heating element (23).

The energization of the heating element (23) is controlled as described above, but if a higher temperature is required or if a lower temperature is desired, the variable resistor (7) is operated to set the desired temperature. You can That is, the resistance value is changed by operating the variable resistor (7), and thus the way the charging voltage of the capacitor (5) rises is changed to change the set temperature. For example, when the temperature setting is “high”, the resistance value VR of the variable resistor (7) is set to VR = 0, and conversely, when VR is set to “low”, VR = MAX. , "Low" is a slow rise.

What is shown in FIG. 3A is the heating element (2
3) Shows the state of change in ambient temperature up to the set temperature. With the change in the wattage of the heating element (23) shown in FIG. 3B, control is performed up to the set temperature without sudden temperature change. It has been shown that.

Next, another embodiment of the present invention will be described with reference to FIGS.

FIG. 5 is a circuit diagram showing an entire electronically controlled kotatsu using the temperature control device of the present invention, and (27) is a microcomputer. In the other embodiment, the microcomputer (2
7) is used. FIG. 6 is an extract of a characteristic circuit of the present invention for controlling the temperature detection and the trigger signal of the semiconductor control means (24). The operation of the other embodiment will be described in detail below with reference to FIGS. 6 and 7.

The waveform diagram shown in FIG. 7 shows the waveforms of the voltages at the input / output terminals and the respective parts of the control circuit shown in FIG.

The microcomputer (27) detects the zero-cross pulse Pz and, as a result, outputs the reset pulse Pr from the terminal R4. When the reset pulse Pr becomes "L" level, the voltage from the terminal R1 starts charging the capacitor (5) via the variable resistor (29) and the resistor (30). The variable resistor (29), like the variable resistor (7) of the above embodiment, is a variable volume for temperature setting and can change the value of the charging resistance to the capacitor (5). The charging voltage at this time is Vc. Next, when the reset pulse Pr becomes "H" level, the transistor (32) turns on and the capacitor (5)
The charging voltage Vc of is discharged.

On the other hand, in order to detect the internal temperature of the kotatsu, a thermistor having a negative characteristic (hereinafter referred to as the thermistor) of the temperature sensing means (8) installed at a predetermined position in the kotatsu is connected in series with the resistor (33). The connection is also connected to the-input terminal of the comparison circuit (10). Therefore, the level of the voltage V _{Th at} the connection point rises as the temperature inside the kotatsu rises.

Here, when the kotatsu temperature is low, that is, the temperature setting is "high".
The operation in this case will be described with reference to the first part of FIG.

The charging voltage Vc and the voltage V _Th are compared by the comparison circuit (10). The comparison result is input to the terminal K4 of the microcomputer (27) via the transistor (34). The microcomputer (27) determines whether the comparison result is the “H” level at every 90 ° of the AC voltage waveform, and if the comparison result is the “L” level at this time, that is, the charging voltage Vc> the voltage V If _Th , the pulse signal R _R2 is output to the terminal R2. The pulse signal P _R2 is output at the timing when the heating element (23) is energized by about 100%. That is, if the pulse signal P _R2 is output immediately after the zero-cross pulse Pz is output, the comparison output from the comparison circuit (10) is converted into the capacitor (35).
This is because it can be applied to the base of the transistor (36) at a timing earlier than the trigger pulse V _B obtained via The collector of this transistor (36) has a resistor (37)
It is connected to the gate of the semiconductor control means (24) via, and the semiconductor control means (24) is triggered at the timing of the pulse signal P _R2 to energize the heating element (23).

Next, when the temperature inside the kotatsu approaches the set temperature at the temperature setting “high”, as shown in the second and third parts of FIG. 7, the charging voltage Vc <the voltage Vc at the time of the AC voltage waveform 90 °.
_Th next, thus the terminal K4 of the microcomputer (27) "H" level signal is input. Therefore, the microcomputer (27) does not output the pulse signal P _R2 from the terminal R ₂ because the charging voltage Vc has not reached the voltage V _Th .
However, when the charging voltage Vc and the voltage V _Th match, the comparison means (10) outputs a high potential level signal, the voltage of the terminal R1 is differentiated by the capacitor (35) and the resistance (38), and the trigger is generated. Obtain the pulse V _B. The transistor (36) is turned on by this trigger pulse V _B , a gate signal flows to the semiconductor control means (24) at the intersection angle of Vc = V _Th , and the heating element (23) is turned on and the phase is controlled. At this time, the microcomputer (27) shifts the time point for judging the comparison result from every 90 ° of the AC voltage waveform, for example, every 60 °. That is, the predetermined time is shortened. Therefore, similarly to the above-described embodiment, it is possible to minimize the temperature change due to the change from 100% energization to 50% energization when the phase control is replaced. Then, after the temperature has once dropped, the determination time is shifted forward, so that the phase control corresponding to the temperature is continued. Duty factor (w
Since the number) is larger than the w number that maintains and stabilizes the temperature in the kotatsu, the temperature in the kotatsu keeps increasing and therefore the voltage V _Th also keeps increasing. As a result, the charging voltage Vc and the voltage V _Th
The intersection (coincidence point) with shifts to the right side as shown in the second and third parts of FIG. 7, so the energization rate gradually decreases. The third part of FIG. 7 shows the case where the temperature inside the kotatsu reaches the set temperature when the temperature is set to "high", and when the duty factor (the number of w) decreases to a w number at which the temperature inside the kotatsu can be maintained, The rise in internal temperature stops.

When the temperature setting is changed to “low”, as shown in the third part of FIG. 7, the peak of the charging voltage Vc decreases and the intersection point with the voltage V _Th , that is, the coincidence point disappears, and the heating element (23) is reached. Is no longer energized. That is, when the heating element (23) is a lamp heater, the lamp heater is turned off. In this case, since the kotatsu user wanted to lower the temperature, the temperature setting was changed to the "low" side, so turning off the lamp heater gives the user a feeling that the kotatsu temperature has dropped (actually It goes down), so it's better to turn it off. Then, since the lamp heater is turned off, the temperature inside the kotatsu gradually decreases, and when approaching the "low" set temperature, the charging voltage Vc and the voltage V _Th match (cross), but this crossing angle is the energization rate. Since it is close to 0%, the temperature inside the kotatsu continues to drop. The intersection of the charging voltage Vc and the voltage V _Th shifts to the left side in FIG. 6 as the temperature in the kotatsu decreases, so that the duty factor increases and eventually the setting setting of “low” is maintained. Stable at required wattage. In other embodiments, the input of the terminal K4 is detected at 90 ° and 60 °,
Since it is processed by a microcomputer, by changing the detection angle according to the size of kotatsu and the w number of the heating element (23), it is possible to easily set the energization range of about 100% to the range suitable for kotatsu use. You can

(G) Effect of the Invention According to the present invention, it is possible to prevent the lamp heater, which is a heating element, from becoming bright or dark by providing a hysteresis by resetting the time until temperature detection is set short. A temperature control device capable of That is, since the control is not such that the energization amount changes abruptly, when used for kotatsu, abrupt change of the internal temperature is prevented.

[Brief description of drawings]

FIG. 1A is a circuit diagram of an embodiment of the present invention, FIG. 1B is a circuit diagram of a main part of the embodiment, FIGS. 2A and 2B are waveform diagrams for explaining the operation of the embodiment, and FIG. And B are graphs showing changes in the ambient temperature of the heating element and graphs showing changes in the wattage of the heating element, respectively, and FIG. 4 is a graph for explaining the operation of the embodiment with the transition of a predetermined time. 5 and 6 are overall circuit diagrams and main circuit diagrams of another embodiment, respectively, and FIG. 7 is a waveform diagram for explaining the operation of the other embodiment.
8 and 9 are conventional circuit diagrams. (4) …… Time changing means, (5) …… Capacitor,
(8) …… Temperature sensing means, (11) …… Judgment means, (16) ……
Duty factor control means, (23) ... Heating element.

Claims (1)

[Claims] 1. A temperature control device comprising a heating element and a temperature sensing means for detecting a change in ambient temperature due to the heating element, wherein the temperature control device controls energization of the heating element according to a signal from the temperature sensing means. A zero potential detecting means for detecting a zero potential point, a capacitor which is repeatedly charged and discharged in synchronization with the output of the zero potential detecting means, and a charging voltage of this capacitor and a voltage of a signal of the temperature sensing means are compared. During the time from the start of charging of the comparator and the capacitor to the reversal of the output of the comparator, the time t1 determined to fully energize the heating element.
Then, after the lapse of that time, a determination means for comparing a predetermined time t2 so as to shift to phase control, and when t1 <t2 according to the output of the determination means, the heating element is fully energized. Phase control means for energizing the heating element by phase control when heat is generated and t1> t2, and time changing means for changing the predetermined time t2 to a predetermined time shorter than that when once t1> t2. A temperature control device comprising: