JPS6237524Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Technical Field) The present invention relates to a temperature control device for a hair dryer.

(Background Art) FIG. 1 shows the configuration of a conventional hair dryer, in which A is a configuration diagram showing the mechanical structure, and B is a circuit diagram thereof. In the figure, A is a main body case, and a suction port 1 is provided at the rear end and a discharge port 2 is provided at the front end. Reference numeral B designates an air blower installed at the suction port inside the main body case A, and the fan 4 is rotated by a motor 3 to blow air to the discharge port. A heater C is provided between the blower B and the discharge port 2, and is made up of a heater coil 6 wound around a cross-shaped heater board 5.
A voltage dividing resistor 7 for lowering the voltage applied to the motor 3, an overtemperature rise preventer 8 such as a thermostat, etc. are attached to the motor 3. D is a hair styling and drying attachment detachably provided at the outlet of the main body case A, and E is a circuit board for motor rectification and noise prevention circuit. Further, numeral 9 indicates a temperature fuse, which together with the above-mentioned overtemperature rise preventer 8 forms a double safety mechanism.

By the way, the above-mentioned hair dryer is used to dry and style hair by combing or wrapping the hair with an attachment D such as a comb or brush, but the outlet port is often blocked by hair during drying and styling. , there are problems such as the increase in air temperature, which may damage the hair or cause the attachment to become deformed due to heat.

In the hair dryer shown in Fig. 1, in order to solve the above-mentioned problem, a temperature rise preventer (thermo switch) 8, which opens and closes mechanical contacts using a bimetal, is connected in series to the heater C, and changes in the air temperature are detected. The air temperature was controlled by turning on and off power to heater C.

However, the bimetallic thermoswitch has large variations in detected temperature, making it difficult to accurately control the air temperature, and its response speed is slow, so it will only operate if the discharge port is blocked or the motor stops for some reason. It took several seconds to more than ten seconds for the heater to heat up, and during this time, not only did the heater become red hot, but if dust etc. had accumulated there was a possibility that an accident could occur, such as smoke.

(Purpose of the invention) The present invention was proposed in view of the above points, and it focuses on the fact that the resistance value of the heater changes due to the red heat of the heater, and the current changes, and detects the change in the heater current. An object of the present invention is to provide a highly safe temperature control device for a hair dryer by quickly cutting off power to a heater when the heater is turned off.

(Disclosure of the invention) FIG. 2 shows an embodiment of the invention constructed from a specific circuit. Broadly speaking, the circuit consists of a blower block a, a heater current detection circuit b, an upper and lower limit setting circuit c, and a phase control circuit d. In the figure, R _L indicates a heater, which is connected in series with the switch element TRIAC of the phase control circuit d and connected to a commercial power source. The blower block a has a rectifier bridge Ref ₁ , a choke coil L _M1 , L _M2 ,
It consists of a capacitor _CM , a chiyoke coil _LM
1 , L _M2 , and capacitor C _M are for noise prevention.
Note that R _M is a resistor for lowering the motor voltage. Next, the heater current detection circuit b includes a resistor _RK inserted in the current path of the heater _RL , and a rectifier bridge that rectifies and smoothes the alternating current voltage generated across this _RK .
It consists of Ref ₂ , resistor R ₁ , and capacitor C ₁ . Next, the upper and lower limit setting circuit C is a comparator.
CM ₁ , CM ₂ and the resistor R ₂ that creates the comparison reference voltage
R ₅ , input resistors R _1N1 , R _1N2 , a rectifier bridge Ref ₃ that functions as a kind of switch, a rectifier diode D _SM , a Zener diode ZD, etc. for supplying power. In addition, the phase control circuit d consists of a resistor (a positive characteristic thermistor is also acceptable) R _th , a capacitor _CT , and a trigger element that constitute the phase shift circuit.
Consists of SBS and switch element TRIAC.

In the circuit shown in FIG. 2, the current of the heater R _L is detected by the resistor R _K , converted to a DC voltage signal, input to the comparators CM ₁ and CM ₂ , and compared with the upper and lower limit values. Then, if the heater current is normal and within the specified value, the outputs of comparators CM ₁ and CM ₂ will both be high level, and the rectifier bridge Ref ₃ will not sink, determined by the resistance R _th of the phase shift circuit and the capacitor _CT. At the phase angle, switch element TRIAC is triggered and continues to power heater R _L .
On the other hand, if the heater temperature rises excessively for some reason and the detection voltage falls outside the specified value, comparators CM ₁ and CM ₂
The output of one of them is inverted to a low level, and the rectifier bridge Ref ₃ sucks the current flowing into the capacitor _CT , so that the switch element TRIAC is turned off and the power supply to the heater R _L is cut off. At this time, since there is almost no transient response from abnormality detection to heater shutdown, the heater does not become red hot or smoke, and operates as an ideal quick-actuation overheat prevention device. Furthermore, by using a heat-sensitive element such as a positive temperature coefficient thermistor for the resistor R _th of the phase shift circuit, it is possible to normally maintain the air temperature constant and to shut off the heater in the event of an abnormality.

(Effects of the invention) As described above, in the present invention, in a hair dryer that includes an air blowing section and a heating section and controls the output of the heating section, a signal corresponding to the current of the heater of the heating section is sent. A detection section that outputs an output, a comparison section that compares the output value of this detection section with a fixed value to determine whether it is normal or not, and turns on and off power supply to the heater of the heating section according to the output of this comparison section. (a) Since the heater current can be detected as it is, any abnormal condition can be detected and the heater can be shut off reliably.

(b) It has almost no transient response time compared to conventional bimetal type circuits, so it is quick-acting and safe.

It has the following effects.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram showing a conventional hair dryer, A is a structural diagram, B is a circuit diagram thereof, and FIG. 2 is a circuit diagram showing an embodiment of the present invention. a...Blower block, b...Heater current detection circuit, c...Upper/lower limit setting circuit, d...Phase control circuit, R _L ...Heater, TRIAC...Switch element,
_RK ...Resistance.

Claims (1)

[Scope of utility model registration request] A hair dryer comprising an air blowing section and a heating section, and controlling the output of the heating section, further comprising a detection section that outputs a signal according to a current of a heater of the heating section, and an output value of the detection section that is set to a constant value. A comparison section that compares and determines whether or not it is normal; and a comparison section that turns on/off power supply to the heater of the heating section according to the output of this comparison section.
1. A temperature control device for a hair dryer, comprising a switch section that turns off.