JPH0667440B2 - Clothes dryer control device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for a clothes dryer that is operation-controlled by a microcomputer, and particularly for generating hot air even when a malfunction such as a runaway of the microcomputer occurs. The present invention relates to a control device for a clothes dryer in which safety is improved without energizing only a heater provided in the.

[Background of the Invention]

BACKGROUND ART Conventionally, in a clothes dryer control device that is operation-controlled by a microcomputer, a bidirectional three-terminal thyristor that controls on / off of a motor that is a drive source of a fan that introduces dry air into a drying chamber that stores clothes, And a motor control circuit including the gate drive circuit, a bidirectional three-terminal thyristor for controlling opening and closing of energization of a heater serving as a heating source of introduced air, and a heater control circuit including the gate drive circuit It was independent from the output part of.

A circuit diagram of a conventional example is shown in FIG. In FIG. 2, 1 is a commercial power source, 2 is a power source opening / closing switch, 3 is a door switch that opens and closes contacts as a door (not shown) is opened and closed, 4 is a control unit, and 5 is for obtaining a DC power source from the commercial power source. DC power supply device, 6 is a microcomputer, 7 is an input operation unit for the user to set operating conditions, 8 is a display output unit for notifying the user of the operating condition, 9 and 10 are heaters, 11 Is a motor, 12 and 13 are bidirectional three-terminal thyristors that control the energization of the heaters 9 and 10, respectively, and 14 is a bidirectional three-terminal thyristor that controls the motor 11 to be turned on and off, 15, 16 and 17
Are the transistors that drive the bidirectional three-terminal thyristors 12, 13, and 14, respectively, 18, 19 and 20 are the gate current limiting resistors of the bidirectional three-terminal thyristors 12, 13 and 14, respectively, and 21, 22 and 23 are the transistors, respectively. These are 15, 16 and 17 base current control resistors. In the above circuit, the microcomputer 6 receives the input from the input operation unit 7, outputs it to the display output unit 8, and transistors 15, 1 according to the stored program.
For example, the command signal from the microcomputer 6 to the transistor 15 is used for the energization control of the heaters 9 and 10 and the on / off control of the motor 11 for performing the operation control of the clothes dryer by outputting to the bases of 6,17. When the level is high, the transistor 15 is turned on, current flows through the gate of the bidirectional three-terminal thyristor 12, the bidirectional three-terminal thyristor 12 is turned on, and the heater 9 is energized. On the contrary, when the level is low, the transistor 15 and the bidirectional three-terminal thyristor 12 are turned off, and the heater 9 is not energized. The heater 10 and the motor 11 are similarly controlled. In the operation control program stored in the microcomputer 6, the heaters 9 and 10 are
When energized, the motor 11 is programmed to be energized to rotate a fan (not shown). As a result, the drying air passes through the heaters 9 and 10 to become warm air, and the clothes are touched to dry the clothes.
Since the air passes through when the power is on, the heaters 9 and 10 are consequently cooled, and the temperature does not rise abnormally.

However, the microcomputer 6 is
Occasionally, an external electromagnetic interference such as power supply noise or lightning dielectric may cause a runaway and malfunction, and at that time, output may occur regardless of the program. When the computer 6 runs away and a high level voltage is applied to the base of the transistor 15 or 16 and a low level voltage is applied to the base of the transistor 17, the motor 11 is not energized and the heater 9 or 10 or the heater Since both 9 and 10 are energized, and the heaters 9 and 10 are not blown, it is dangerous because they overheat. If only the heater is energized, the user cannot know this and there is a risk of fire or burns.

[Object of the Invention]

An object of the present invention is to solve the above-mentioned problems in the prior art, and even when the microcomputer malfunctions such as runaway, the heater is never energized,
A circuit outside the microcomputer is devised so that the motor is always energized when the heater is energized, and an extremely safe clothes dryer control device is provided. .

[Outline of Invention]

In the present invention, in order to achieve the above object, both a motor that serves as a drive source for a fan that introduces drying air, a heater that serves as a heating source for the introduced air, and a motor that controls opening and closing of electricity to the heater are both provided. In a controller of a clothes dryer having a directional three-terminal thyristor, a gate drive circuit that outputs a gate signal that controls ON / OFF of each thyristor, and a microcomputer that outputs a control signal that controls these gate drive circuits The gate drive circuit is composed of a switch element for turning on / off a gate signal and a current limiting resistor connected in series with this switch element. The switch element of the gate drive circuit of the thyristor for controlling the heater controls the motor. It is configured to be connected in series with the switch element of the gate drive circuit of the thyristor.

Example of Invention

A circuit diagram of an embodiment of the present invention is shown in FIG. In FIG. 1, the same reference numerals as those in the conventional example of FIG. 2 indicate the same components that perform the same operation. The difference between FIG. 1 and FIG. 2 lies in the connection method of the transistors 15, 16 and 17. is there. That is, the second
In the conventional example shown in the figure, the three transistors 15, 16 and 17 each constitute an independent switch element, whereas in the circuit of the embodiment shown in FIG. 1, the switch function by the transistor 15 and the switch function by the transistor 17 are provided. Are connected in series, and the switching function of the transistor 16 and the switching function of the transistor 17 are connected in series. More specifically, the three transistors 15, 16 and 17 are NPN type bipolar transistors, and the transistor 15
The emitter terminal of is connected to the collector terminal of transistor 17, and the emitter terminal of transistor 16 is also a transistor
It is connected to the collector terminal of 17 and each transistor 15,16,17
Each collector terminal of the gate current limiting resistor 18,19,
It is connected to the gate terminals of the bidirectional three-terminal thyristors 12, 13, and 14 via 20, and the emitter terminal of the transistor 17 is connected to one (negative side) terminal of the DC power supply device 5, and each of the transistors 15, 16, 17 base terminals are base current limiting resistors
It is configured to be connected to the microcomputer 6 via 21, 22, and 23.

With this configuration, even if the microcomputer 6 may run out of order and malfunction due to external electromagnetic interference, if the control signal from the microcomputer 6 to the base of the transistor 17 is at a low level, the transistor 15
Alternatively, even if the control signal to the base of 16 is at a high level, the transistor 15 or 16 is not turned on and the heater 9 or 10 is not energized. On the other hand, when the high level command output is output to the base of the transistor 17 and the output to the bases of the transistors 15 and 16 is high level, the heater 9 or 10 is energized. Since the motor 11 is also energized, the heaters 9 and 10 are blown by the fan rotation, and there is no risk of overheating.

Unlike the conventional example described above, since only the heaters 9 and 10 are not energized by the malfunction of the microcomputer 6, it is possible to obtain a safe dryer.

[Effects of the Invention] As described above, according to the present invention, even when the microcomputer malfunctions due to a runaway electromagnetic interference or the like, the heater is never energized.
When the heater is energized, the motor is always energized so that the fan blows air through the heater. Therefore, there is no danger of overheating of the heater, and a very safe clothes dryer can be obtained.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention, and FIG. 2 is a circuit diagram showing a conventional example. 1 ... Commercial power supply, 3 ... Door switch, 5 ... DC power supply device, 6 ... Microcomputer, 9,10 ... Heater,
11 …… Motor, 12,13,14 …… Bidirectional three-terminal thyristor, 15,16,17 …… Transistor.

Claims (1)

[Claims] 1. A motor as a driving source of a fan for introducing drying air into a drying chamber containing clothes, a heater as a heating source for the introduced air, and an opening / closing control of energization to the motor and the heater. A bidirectional three-terminal thyristor connected to each of the motor and the heater, a gate drive circuit that outputs a gate signal that controls on / off of these thyristors, and a micro that outputs a control signal that controls these gate drive circuits. In a clothes dryer control device having a computer, the gate drive circuit includes a switch element for turning on / off a gate signal in response to a control signal from a microcomputer, and a current limiting resistor connected in series with the switch element. The switch element for driving the gate of the thyristor for controlling the heater is a switch for controlling the motor. Control device for a clothes dryer, characterized in that connected to the switch element in series for the gate drive of the lister.