TWI501062B - Constant temperature control circuit and electric appliance - Google Patents

Description

Temperature constant temperature control circuit and electrical device

The invention relates to a temperature constant temperature control circuit and an electrical device, and in particular to a temperature constant temperature control circuit and an electrical device with a constant temperature control function.

With the development and advancement of technology, home appliances have also developed many different functions for different needs of users. For example, many home appliances (eg, hair dryers, incubators, etc.) mostly have thermostatically controlled functions. For home appliances that generally have a constant temperature control function, the most common method at present is to use the thermostatic control circuit to realize the temperature control function. In the technical field of conventional thermostatic control circuits, temperature control is required via an amplifier or a microprocessor chip. For example, the thermostat control circuit controls the heater elements in the thermostat control circuit to adjust the temperature according to the control voltage of the amplifier. On the other hand, the thermostat control circuit that uses the microprocessor chip requires an additional program to control the operation of the circuit.

However, if the thermostat control circuit uses an amplifier to control the temperature, it will make The overall manufacturing cost increases, and the use of micro-processed wafers increases the complexity of the circuit design. In the case of a household appliance with thermostatic control function, if a micro-processed wafer is used as the main core in the thermostatic control circuit module, the temperature sensing device must first pass through the micro-processed wafer and the control program to determine whether to turn on the heating system and The air supply system adds a lot of circuit design costs.

The invention provides a temperature constant temperature control circuit and an electrical device, which use a transistor to replace an amplifier and a microprocessor to control a constant temperature circuit, thereby reducing circuit manufacturing cost and circuit complexity.

The temperature constant temperature control circuit of the present invention is coupled to the heating element. The temperature thermostat control circuit includes a temperature detector, a control signal generator, and a switching element. The temperature detector is used to detect the ambient temperature and generate a detection voltage according to the ambient temperature. The control signal generator is coupled to the temperature detector, and the control signal generator has at least one transistor, and the control terminal of the at least one transistor receives the detection voltage and generates a control signal accordingly. The switching element is coupled between the control signal generator and the operating power source, and the switching element receives and turns on or off according to the control signal, thereby controlling whether the heating element performs a heating action.

In an embodiment of the invention, the temperature detector includes a thermistor and a first resistor coupled to the thermistor. The thermistor and the first resistor have different detection voltages due to different resistance values.

In an embodiment of the invention, the at least one transistor includes the first a transistor and a second transistor. The first transistor has a first end, a control end and a second end, and the control end of the first transistor is coupled to the temperature detector to receive the detection voltage. The second transistor has a first end, a control end and a second end. The control end of the second transistor is coupled to the control end of the first transistor to receive the detection voltage.

In an embodiment of the invention, the control signal generator further includes a first diode, a second diode, a step-down circuit, and a capacitor. The cathode end of the first diode is coupled to the first end of the first transistor. The anode end of the second diode is coupled to the first end of the second transistor, and the cathode end of the second diode is coupled to the anode end of the first diode. The buck circuit is connected in series between the paths at which the switching elements receive the control signals. The capacitor is connected in series between the anode terminal of the first diode and the voltage rail.

In an embodiment of the invention, the step-down circuit includes a third diode and a fourth diode. Wherein the anode end of the third diode and the cathode end of the fourth diode are coupled to the first diode and the second diode, and the cathode end of the third diode and the anode of the fourth diode Extremely commonly coupled to the switching element.

In an embodiment of the invention, the first transistor is an NPN bipolar junction transistor, and the second transistor is a PNP bipolar junction transistor.

In an embodiment of the invention, the temperature constant temperature control circuit further includes a voltage stabilization circuit coupled to the temperature detector. The voltage stabilizing circuit is configured to provide an operating power source, and the voltage stabilizing circuit has at least one first Zener diode and at least one second Zener diode. The anode end of the at least one first Zener diode is coupled to the anode end of the at least one second Zener diode.

In an embodiment of the invention, the switching element may be a three-terminal double The relay fluid (Triac) or relay (Relay).

The electrical device of the present invention includes a heater having a heating element and a temperature thermostat control circuit. The temperature thermostat control circuit includes a temperature detector, a control signal generator, and a switching element. The temperature detector is used to detect the ambient temperature and generate a detection voltage according to the ambient temperature. The control signal generator is coupled to the temperature detector, and the control signal generator has at least one transistor, and the control terminal of the at least one transistor receives the detection voltage and generates a control signal accordingly. The switching element is coupled between the control signal generator and the operating power source, and the switching element receives and turns on or off according to the control signal, thereby controlling whether the heating element performs a heating action.

In an embodiment of the invention, the heating element includes a temperature control selection switch, a first heating wire, and a second heating wire. The temperature control selector switch provides a selection signal. The first heating wire is coupled to the switching element to perform a heating operation according to the selection signal and the on or off state of the switching element. The second heating wire is coupled to the temperature control selection switch, and performs a heating operation according to the selection signal and the on or off state of the switching element.

In an embodiment of the invention, the electrical device further includes an actuator control switch and an actuator. The actuator is coupled to an actuator control switch, wherein the actuator controls the switch to control the actuator.

Based on the above, the temperature constant temperature control circuit and the electrical device of the present invention use a temperature detector to detect the ambient temperature and generate a detection voltage, and the transistor in the control signal generator generates a control signal after receiving the detection voltage. The switching element controls whether the heating element performs a heating action to adjust the ambient temperature according to the control signal. In this way, the temperature thermostat control circuit no longer needs to configure an amplifier or a microprocessor, nor does it need to By writing additional control programs, you can control the thermostat system, which not only simplifies the circuit but also reduces the cost of circuit development.

The above described features and advantages of the invention will be apparent from the following description.

100,200‧‧‧temperature constant temperature control circuit

102, 202‧‧‧ Temperature detector

104, 204‧‧‧Control signal generator

106, 206‧‧‧ Switching components

120, 220, 320‧‧‧ heating elements

208‧‧‧Buck circuit

210‧‧‧ Voltage regulator circuit

300‧‧‧Electrical devices

310‧‧‧heater

322‧‧‧temperature control switch

324, 326‧‧‧ heating wire

340‧‧‧Actuator control switch

360‧‧‧Actuator

C‧‧‧ capacitor

D1~D4‧‧‧ Diode

E1, E2‧‧‧ endpoint

PL1‧‧‧ voltage trajectory

Q, Q1, Q2‧‧‧ transistor

R1‧‧‧first resistance

RT‧‧‧Thermistor

S1, S2‧‧‧ control signals

V1, V2‧‧‧ detection voltage

VDD‧‧‧Operating power supply

Z1, Z2‧‧‧ Zener diode

FIG. 1 is a schematic diagram of a temperature thermostat control circuit 100 according to an embodiment of the invention.

2 is a schematic diagram of a temperature thermostat control circuit 200 according to another embodiment of the present invention.

FIG. 3 is a schematic diagram of an electrical device 300 according to an embodiment of the invention.

FIG. 1 is a schematic diagram of a temperature thermostat control circuit 100 according to an embodiment of the invention. The temperature thermostat control circuit 100 includes a temperature detector 102, a control signal generator 104, and a switching element 106. The temperature detector 102 is configured to detect an ambient temperature and generate a detection voltage V1 according to the ambient temperature. The control signal generator 104 is coupled to the temperature detector 102, and the control signal generator 104 has at least one transistor Q. The control terminal of the transistor Q is configured to receive the detection voltage V1, and the control signal generator 104 generates the control signal S1 according to the detection voltage V1. The switching element 106 is coupled between the control signal generator 104 and the operating power supply VDD. The switching element 106 is coupled to the heating element 120. The switching element 106 is configured to receive the control signal S1 and turn on or off according to the control signal S1, thereby controlling whether the heating element 120 performs a heating operation.

For example, the temperature detector 102 can be a thermal resistor having a negative temperature coefficient (NTC). When the ambient temperature rises, the resistance of the thermistor decreases due to the negative temperature coefficient characteristic of the thermistor. On the other hand, when the ambient temperature decreases, the resistance of the thermistor increases. Therefore, the temperature detector 102 can generate a corresponding detection voltage V1 according to different ambient temperatures. It is to be noted that in the embodiment of the present invention, the control signal generator 104 has at least one transistor Q therein, but the present invention is not limited thereto. The circuit designer can configure a different number of electro-crystals Q in the control signal generator 104 depending on the situation. In this embodiment, at least one of the transistors Q may be a bipolar junction transistor (BJT) or a metal-oxide-semiconductor field-effect-transistor (MOSFET). The switching element 106 can be a triac, a relay, or other electronic component having a switching function. The heating element 120 can be a heating wire or other electronic component having a heating function.

Of course, the temperature detector 102 can also be a thermistor with a positive temperature coefficient (PTC). The above description is only an example and is not intended to limit the scope of the invention.

As can be seen from the above description, the temperature thermostat control circuit 100 detects whether the heating element 120 is to be heated by detecting the ambient temperature. From another point of view, the temperature thermostat control circuit 100 can utilize whether the heating element 120 is heating To achieve the function of temperature control, and to maintain the ambient temperature at a constant temperature. For example, suppose the user wants the ambient temperature to be maintained at 50 ° C. When the temperature detector 102 (eg, the thermistor) detects that the ambient temperature is lower than 50 ° C or higher than 50 ° C, the thermistor is used according to the environment. The temperature detector 102 can change the voltage value of the generated detection voltage V1 correspondingly to the difference in temperature. After the transistor Q (for example, BJT) of the control signal generator 104 receives the different detection voltage V1, the BJT may be turned "ON" or "OFF". Whether or not the switching element 106 (for example, Triac) is turned on can be controlled by ON or OFF of the BJT. When the ambient temperature is lower than 50 ° C, the Triac is turned on, and the operating power supply VDD is supplied to the heating element 120 (for example, the heating wire), and the current flows through the heating element 120, and the heating wire starts to heat until the temperature When the detector 102 detects that the ambient temperature reaches 50 ° C, the heating wire will turn off and no longer heat. On the other hand, when the temperature detector 102 detects that the ambient temperature is 50 ° C, the Triac is not turned on, the operating power supply VDD is not supplied to the heating wire, the current does not flow through the heating wire, and the heating wire is not heated. By the above method, the ambient temperature can be maintained at 50 °C.

In order to explain in detail the internal operation of the temperature constant temperature control circuit 100, please refer to FIG. 2 below. 2 is a schematic diagram of a temperature thermostat control circuit 200 according to another embodiment of the present invention. The temperature thermostat control circuit 200 includes a temperature detector 202, a control signal generator 204, a switching element 206, a step-down circuit 208, and a voltage stabilizing circuit 210. Referring to FIG. 1 and FIG. 2 simultaneously, the temperature detector 202, the control signal generator 204, and the switching element 206 of FIG. 2 can be regarded as the temperature detector 102, the control signal generator 104, and the switching element 106 of FIG. The difference between Figure 2 and Figure 1 is that The temperature thermostat control circuit 200 of FIG. 2 further includes a buck circuit 208 and a voltage stabilizing circuit 210.

The temperature detector 202 includes a thermistor RT and a first resistor R1. The first resistor R1 is coupled to the thermistor RT, and the thermistor RT and the first resistor R1 divide the operating power VDD between the terminals E1 and E2 to generate the detection voltage V2. The stable operating power supply VDD can be generated by the voltage stabilizing circuit 210 coupled to the temperature detector 202. In other words, the thermistor RT and the first resistor R1 generate different detection voltages V2 due to different resistance values. In this embodiment, the voltage stabilizing circuit 210 has at least one Zener diode Z1 and at least one Zener diode Z2. The anode end of the at least one Zener diode Z1 is coupled to the anode end of the at least one Zener diode Z2.

For example, when the voltage value applied to the terminal E1 is higher than the voltage value of the terminal E2, a stable operating power VDD can be provided between the terminals E1 and E2 by the collapse phenomenon of the Zener diode Z1. In contrast, when the voltage value applied to the terminal E2 is higher than the voltage value of the terminal E1, the stable operating power VDD can be provided between the terminals E2 and E1 by the collapse phenomenon of the Zener diode Z2. It should be noted that the present invention does not limit the number of Zener diodes in the voltage stabilizing circuit 210. The circuit designer can configure different numbers of Zener diodes in the voltage stabilizing circuit 210 according to different situations. In other embodiments, the plurality of Zener diodes may be connected in series with the Zener diode Z1 and the Zener diode Z2 in the same direction.

Further, the number of the Zener diodes described above may be determined according to the voltage value of the operating voltage VDD and the magnitude of the breakdown voltage of each Zener diode.

It can be known from the above description that the temperature constant temperature control electric power of the embodiment of the present invention The road 200 can receive AC power for operation.

The control signal generator 204 includes a transistor Q1, a transistor Q2, diodes D1, D2, and a capacitor C. In this embodiment, the patterns of transistor Q1 and transistor Q2 may be complementary. For example, the transistor Q1 may be an NPN bipolar junction transistor, and the transistor Q2 may be a PNP bipolar junction transistor. The transistor Q1 has a first end (eg, a collector terminal), a control terminal (eg, a base terminal), and a second terminal (eg, an emitter terminal). The control terminal of the transistor Q1 is coupled to the temperature detector 202 to receive the detection voltage V2. . The transistor Q2 has a first end (eg, a collector terminal), a control terminal (eg, a base terminal), and a second terminal (eg, an emitter terminal). The control end of the transistor Q2 is coupled to the control terminal of the transistor Q1 to receive the detection voltage. V2. On the other hand, the cathode end of the diode D1 is coupled to the first end of the transistor Q1, the anode end of the diode D2 is coupled to the first end of the Q2 of the transistor, and the cathode end of the diode D2 is coupled to the diode. The anode end of D1. The capacitor C is connected in series between the anode terminal of the diode D1 and the voltage rail line PL1 for stabilizing the voltage of the control signal S2.

The step-down circuit 208 is connected in series between the paths at which the switching element 206 receives the control signal S2, and thereby performs a step-down operation on the control signal S2 generated by the control signal generator 204. The step-down circuit 208 includes a diode D3 and a diode D4, wherein the anode end of the diode D3 and the cathode end of the diode D4 are coupled to the diode D1 and the diode D2, and the diode D3 The cathode end and the anode end of the diode D4 are coupled to the switching element 206.

In addition to this, the switching element 206 (eg, Triac) is coupled to the heating element 220 (eg, a heating wire). In this embodiment, the control signal generator 204 utilizes The transistor Q1 and the transistor Q2 receive the detection voltage V2, and generate a control signal S2 (for example, a voltage signal) according to the detection voltage V2. After the control signal S2 passes through the step-down circuit 208, the switching element 206 can be controlled to be turned on or off. When the switching element 206 is turned on, the heating element 220 begins to heat up. On the other hand, when the switching element 206 is turned off, the heating element 220 is not heated.

It should be noted that in this embodiment, two transistors (for example, transistor Q1 and transistor Q2) and two diodes (for example, diode D1 and diode) are disposed in the control signal generator 204. D2), two diodes (for example, diode D3 and diode D4) are arranged in the step-down circuit 208, and a three-terminal bidirectional thyristor (for example, Triac) is used in the switching element 206 to provide two A circuit through which a current can flow. For example, when the transistor Q1 is turned on, current flows through the switching element 206, the diode D4, the diode D1, and the transistor Q1. On the other hand, when the transistor Q2 is turned on, current flows through the transistor Q2, the diode D2, the diode D3, and the switching element 206.

On the other hand, since the temperature thermostat control circuit 200 can receive the AC power supply for operation, it can be known from the description of the voltage stabilizing circuit 210 that the voltage can be applied to the terminal E1 or the end point E2. It can be seen that an alternating voltage can be applied to the terminal E1 or the end point E2 in the temperature constant temperature control circuit 200, and the transistor Q1 and the transistor Q2 disposed in the control signal generator 204 are applied to different terminals due to the alternating voltage. Turn on and off separately to provide different current loops.

The temperature thermostat control circuit 100 and the temperature thermostat control circuit 200 of FIGS. 1 and 2 can be applied to some home appliances that require constant temperature control. Figure 3 illustrates the invention A schematic diagram of an electrical device 300 of an embodiment. The electrical device 300 includes a heater 310, a temperature thermostat control circuit 200, an actuator control switch 340, and an actuator 360. Please refer to the description of FIG. 2 for the operation mode and function of the temperature constant temperature control circuit 200, and details are not described herein. The heater 310 has a heating element 320 therein, wherein the heating element 320 includes a temperature control selection switch 322, a heating wire 324, and a heating wire 326. The temperature control selection switch 322 is used to provide a selection signal. The heating wire 324 is coupled to the switching element 206 to perform a heating operation according to the selection signal and the on or off state of the switching element 206. The heating wire 326 is coupled to the temperature control selection switch 322, and performs a heating operation according to the selection signal and the on or off state of the switching element 206. The electrical device 300 can be a hair dryer with a constant temperature function or other electrical appliances with a constant temperature control function.

For example, when the electrical device 300 is a hair dryer having a constant temperature function, the user can control the air volume (for example, weak wind or strong wind) of the electrical device 300 by using the actuator control switch 340 and the temperature control selection switch 322, respectively. Air outlet temperature (eg low temperature, constant temperature and high temperature) to meet the demand. The actuator 360 can be a motor in the electrical device 300 and the actuator 360 is coupled to the actuator control switch 340. The user can utilize the actuator control switch 340 to adjust the rotational speed of the actuator 360 to vary the amount of output air volume of the electrical device 300. On the other hand, the user can adjust the temperature of the air outlet of the electrical device 300 by using the temperature control selection switch 322.

When the user wants to maintain the temperature of the air outlet of the electrical device 300 at a constant temperature, the temperature control selection switch 322 can be switched to the constant temperature state, and the temperature control selection switch 322 provides a selection signal representative of the constant temperature. Assuming that the temperature control selection switch 322 is switched to the constant temperature state, the outlet temperature of the electric device 300 is set to 50 °C. at this time, If the switching element 206 is turned on, it means that the temperature detector 202 detects that the temperature of the air outlet is lower than 50 ° C, and the heating wire 324 starts to heat until the temperature detector 202 detects that the temperature of the air outlet reaches the original setting. The value is 50 °C. On the other hand, if the switching element 206 is turned off, the heating wire 324 does not need to be heated. In another embodiment, when the user wants to make the temperature of the air outlet of the electrical device 300 low or high, the temperature control selection switch 322 can be switched to a low temperature or a high temperature state, and the temperature control selection switch 322 will Provides a selection signal that represents low or high temperatures.

In this embodiment, the heating wire 324 and the heating wire 326 are respectively a high temperature heating wire and a low temperature heating wire. From another point of view, when the user switches the temperature control selection switch 322 to the constant temperature state, if the temperature detector 202 detects that the air outlet temperature of the electrical device 300 is lower than the set value, then the heating wire is utilized at this time. 324 (high temperature heating wire) for heating operation. On the other hand, when the user does not need to use the thermostatic control function of the electric device 300, the electric device 300 can perform the heating operation using the heating wire 326 (low temperature heating wire).

In summary, the temperature constant temperature control circuit and the electrical device of the present invention utilize a temperature detector to detect the ambient temperature and utilize the conduction or disconnection of the transistor in the control signal generator to control whether the switching element is turned on. When the ambient temperature is lower than the set temperature, the switching element is turned on, and the heating element performs a heating operation, thereby controlling the ambient temperature. In this way, the temperature thermostat control circuit no longer needs to be equipped with an amplifier or a microprocessor, and does not need to write an additional control program to achieve the control of the constant temperature system, which not only simplifies the circuit but also reduces the cost of circuit development.

Although the present invention has been disclosed above by way of example, it is not intended to limit the present invention. The scope of the present invention is defined by the scope of the appended claims, which are defined by the scope of the appended claims, without departing from the spirit and scope of the invention. quasi.

100‧‧‧temperature constant temperature control circuit

102‧‧‧Temperature Detector

104‧‧‧Control signal generator

106‧‧‧Switching elements

120‧‧‧heating elements

Q‧‧‧Optocrystal

S1‧‧‧ control signal

V1‧‧‧Detection voltage

VDD‧‧‧Operating power supply

Claims (14)

A temperature constant temperature control circuit coupled to a heating element, comprising: a temperature detector for detecting an ambient temperature and generating a detection voltage according to the ambient temperature; a control signal generator coupled to the temperature detection a control unit, the control signal generator having at least one transistor, the control end of the at least one transistor receiving the detection voltage and generating a control signal, wherein the at least one transistor comprises: a first transistor having a first end, a control end, and a second end, the control end of the first transistor is coupled to the temperature detector to receive the detection voltage; and a second transistor having a first end, a control end, and a first The control end of the second transistor is coupled to the control end of the first transistor to receive the detection voltage; and a switching element is coupled between the control signal generator and an operating power source, the switch The component receives and is turned on or off in accordance with the control signal, and thereby controls whether the heating element performs a heating operation. The temperature thermostat control circuit of claim 1, wherein the temperature detector comprises: a thermistor; and a first resistor coupled to the thermistor, wherein the thermistor and the first A resistor produces a different detection voltage due to different resistance values. The temperature constant temperature control circuit according to claim 1, wherein the The control signal generator further includes: a first diode, the cathode end coupled to the first end of the first transistor; a second diode, the anode end coupled to the first end of the second transistor, the cathode Extremely coupled to the anode end of the first diode; a step-down circuit connected in series between the path of the switching element receiving the control signal; and a capacitor connected in series at the anode end of the first diode and Between voltage rails. The temperature constant temperature control circuit of claim 3, wherein the step-down circuit comprises: a third diode; and a fourth diode, wherein the anode end of the third diode The cathode end of the fourth diode is coupled to the first diode and the second diode, and the cathode end of the third diode and the anode end of the fourth diode are coupled to the switching element . The temperature constant temperature control circuit according to claim 2, wherein the first transistor is an NPN bipolar junction transistor, and the second transistor is a PNP bipolar junction transistor. The temperature constant temperature control circuit of claim 1, further comprising: a voltage stabilizing circuit coupled to the temperature detector, wherein the voltage stabilizing circuit is configured to provide the operating power source, the voltage stabilizing circuit having at least one a Zener diode and at least one second Zener diode, wherein an anode end of the at least one first Zener diode is coupled to an anode end of the at least one second Zener diode. The temperature constant temperature control circuit according to claim 1, wherein the The switching element can be a three-terminal bidirectional thyristor (Triac) or a relay. An electrical device comprising: a heater having a heating element; and a temperature thermostat control circuit, the temperature thermostat control circuit comprising: a temperature detector for detecting an ambient temperature and generating a temperature according to the ambient temperature Detecting a voltage; a control signal generator coupled to the temperature detector, the control signal generator having at least one transistor, the control end of the at least one transistor receiving the detection voltage and generating a control signal accordingly, The at least one transistor includes: a first transistor having a first end, a control end, and a second end, wherein the control end of the first transistor is coupled to the temperature detector to receive the detection voltage; a second transistor having a first end, a control end, and a second end, wherein the control end of the second transistor is coupled to the control end of the first transistor to receive the detection voltage; and a switching element is coupled Between the control signal generator and an operating power source, the switching element receives and is turned on or off according to the control signal, thereby controlling whether the heating element performs a heating operation. The electrical device of claim 8, wherein the temperature detector comprises: a thermistor; and a first resistor coupled to the thermistor, wherein the thermistor and the first resistor are The operating power source is divided to generate the detected voltage. The electrical device of claim 8, wherein the control signal generator further comprises: a first diode, a cathode end coupled to the first end of the first transistor; and a second diode The anode end is coupled to the first end of the second transistor, the cathode end is coupled to the anode end of the first diode; a step-down circuit is connected in series between the path of the switching element receiving the control signal; and a capacitor Connected in series between the anode end of the first diode and a voltage rail. The electrical device of claim 10, wherein the step-down circuit comprises: a third diode; and a fourth diode, wherein the anode end and the fourth body of the third diode The cathode end of the diode is coupled to the first diode and the second diode. The cathode end of the third diode and the anode end of the fourth diode are coupled to the switching element. The electrical device of claim 8, further comprising: a voltage stabilizing circuit coupled to the temperature detector, the voltage stabilizing circuit for providing the operating power, the voltage stabilizing circuit having at least one first The nano-diode and the at least one second Zener diode, wherein an anode end of the at least one first Zener diode is coupled to an anode end of the at least one second Zener diode. The electrical device of claim 8, wherein the heating element comprises: a temperature control selection switch, providing a selection signal; a first heating wire coupled to the switching element, performing a heating operation according to the selection signal and an on or off state of the switching element; and a second heating wire coupled to the temperature control selection switch according to the selection signal And the heating operation is performed in an on or off state of the switching element. The electrical device of claim 8, further comprising: an actuator control switch; and an actuator coupled to the actuator control switch, wherein the actuator control switch is configured to control the actuation Device.