JPH01291059A - Air blowing temperature control circuit - Google Patents

Abstract

PURPOSE:To prevent an abnormal higher temperature state from being attained at an initial stage of energization, perform a control over an electrical power accompanying its frequent energization and termination and get hot air with a sufficient high temperature by a method wherein an electrical power limiting time applied by a controlling means is made shorter as an energization terminating time in respect to a heating means is short. CONSTITUTION:When a device is energized by turning on a switch, an air blowing means is energized and an air blowing is started toward a heating means. Simultaneously, a controlling means is started to operate, an electrical power is supplied from a commercial AC power supply 8 to the heating means and the blown air is started to be heated. However, at that time, since the controlling means is simultaneously started, a heating operation is carried out while an electrical power to be supplied to the heating means is being restricted. A time for restricting such an electrical power described above is set according to a length of dead time before an energization for the heating means is started. Accordingly, the restricted condition of the supplying of electrical power for the heating means through a controlling means is terminated, sensing means in increased up to a controlling temperature and the state is transferred to a normal temperature controlling state with the sensing means and the controlling means.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a control circuit for controlling the temperature of air blown in an apparatus that performs a predetermined heat treatment using hot air, such as a hair dryer.

[Prior Art] Conventionally, as a method of controlling the blowing temperature of this type, a temperature detection means is provided on the lee side of the hot air, and the electric power supplied to the heating means is controlled in accordance with the detected temperature of the means, thereby controlling the temperature of the hot air. In many cases, the value is kept approximately constant.

However, since the temperature detection means itself has a heat capacity, it is inevitable that a deviation will occur between the actual hot air temperature and the detected temperature at the initial stage of heating, and as a result, more power is supplied to the heating means. The direction of heating was controlled, abnormally high hot air was blown, and there was a risk of damage to the heating means itself. This danger has become more and more common as heating power has increased in recent years. It is becoming r. .

To solve this problem, it is conceivable to forcibly limit the power supplied to the heating means for a certain period of time after starting power supply to the heating means.

[Problem to be solved by the invention J However, heating devices such as hair dryers are often used while repeatedly starting and stopping 1-.
Although the above method can prevent dangers caused by abnormally high temperatures, the safety mechanism operates every time it is started, which often suppresses the hot air temperature more than necessary, and it takes time to send hot air at a sufficiently high temperature. There is a risk that proper heating and cooling may not be possible.

The present invention has been made in view of such problems, and it prevents the risk of abnormally high temperatures at the initial stage of startup, and also performs power control that follows frequent startups and stops, and maintains sufficiently high temperatures. The purpose of the present invention is to provide an air blowing temperature control circuit that can obtain hot air.

[Means for Solving the Problems] FIG. 1 shows the basic configuration of a blowing temperature control circuit configured to achieve the above object, which includes means for heating air sent from a blowing means, means for detecting the temperature of the heated hot air; means for controlling the electric power supplied to the heating means in accordance with the temperature detected by the sensing means; and means for limiting power for a predetermined period of time.

The present invention provides a power limit time by the above-mentioned limiting means,
The present invention is characterized in that the time during which electricity is stopped for the heating means is very short.

[Operation] When the above configuration is adopted and the switch is turned on to start the device, the blowing means is energized and starts blowing air toward the heating means.

At the same time, the control means starts, supplies power from the commercial AC power source 8 to the heating means, and starts heating the air. However, at that time, the limiting means is also activated at the same time, so that heating is performed with the power supplied to the heating means being limited.

The time period during which the electric power is restricted is set in accordance with the length of time during which the heating means is stopped before energization is started. Therefore, the temperature detected by the detection means is fl)lJti
At the same time as the temperature rises to the TI temperature, the state in which the power supply to the heating means is restricted by the restriction means ends, and a transition is made to the normal temperature control state by the detection means and the Ill control means.

[Example] An example in which the present invention is applied to a hand-held hair dryer that only blows air will be shown below. Of course, the same can be applied to the apparatus as well.

The dryer according to the present invention is as shown in FIG.

A heating section 2 is provided in a substantially cylindrical main body case 1, and the base i1 of the main body case 1! Air is blown toward the heating part 2 from the air blowing part 3 provided on the side.Furthermore, a handle 4 extends downward from the base end side of the main body case 1, and inside the handle 4, there is a blowing part 3 and a heating part 2. and a main switch 5 that regulates when to start energizing the section 2.

The heating unit 2 is provided with an electric circuit 6 for controlling power to the heating unit 2, and can be supplied with power from a commercial power source via a power plug 7.

As shown in FIG. 3, the blower section 3 consists of a diode bridge 10 for full-wave rectification and a DC motor 12 that rotationally drives a fan 11. It is connected to one end of the power plug 7, while the other end is connected to the voltage drop resistor 14 and the heating part 2.
By connecting it to the other end of the power plug 7 via the temperature fuse 15, the motor 12 is energized in conjunction with the ON operation of the main switch 5, and the fan 11 is rotated to blow air toward the heating section 2. Let's do it.

The heating section 2 has first and second heaters 16 and 17 having a predetermined power capacity connected in series. A switch 18 is provided in parallel with the second heater 17, and when the switch 18 is turned on, the second heater 16 and 17 are connected in series. By bypassing both ends of the heater 17, the amount of heat generated by the heating section 2 as a whole can be switched between high and low levels θg.

Note that the capacity can also be switched by inserting a diode in series with the heater.

The electric circuit 6 that controls the temperature of the air blower includes a control unit 20 that controls the power supplied to the heating unit 2 to maintain the air temperature at a substantially constant temperature, and a main switch 5 that turns on the air blower. A quick cooling switch 30 that can forcibly stop the power supply to the heating section 2 during operation, a timer section 31 that limits the power supplied to the heating section 2 for a predetermined time in the initial stage of heating, and noise generated during power control. It is composed of a circuit 13 that prevents.

The control unit 20 uses a bidirectional thyristor such as a triac as the phase control element 21, and also uses an SBS
A bidirectional switching element 22 such as the above is provided for generating a trigger signal for the phase control element 21. Furthermore, as a detection element 23 for hot air temperature, on the leeward side of the heating section 2,
A charging/discharging circuit 25 is constituted by a sensing element 23 and a capacitor 24, which includes a thermistor with a positive characteristic whose resistance increases rapidly when the control temperature is exceeded. Therefore, every half cycle of the input commercial AC voltage, the capacitor 24 of the charging/discharging circuit 25 is charged and discharged at a rate determined by the time constant of the circuit 25.
When the voltage across the capacitor 24 exceeds a predetermined value, the switching element 22 is turned on, a trigger signal is sent to the phase control element 21, and the predetermined phase fII+! let him do his thing.

Here, the time constant of the charging/discharging circuit 250 changes depending on the resistance value of the thermistor provided as the sensing element 23, but the thermistor has a positive characteristic and the resistance value rapidly increases when the temperature rises above a predetermined control temperature. This increase in resistance increases the time constant of the charging/discharging circuit 25, increasing the control angle, and restricting the power supplied to the heating section 2 to prevent the air temperature from rising above the control temperature.

The quenching switch 30 frequently switches between hot air and cold air to facilitate hair treatment operations such as curling the hair. By providing the operation knob 32 on the upper part of the main body case l, the operation knob 3 can be easily operated while the main body case 1 is held up.
By simply pressing 2, you can easily and reliably change between cold air and hot air. That is, the quenching switch 3 is closed at the tip of the operating rod 33 that hangs down when the operating knob 32 is pressed.
0 contact to short-circuit both ends of the capacitor 240 of the control unit 20 with the switch contact, and due to this short-circuit, the input of the trigger signal to the phase control element 21 is cut off in a strong flint manner, and the control element 21 is always turned off. , the power to the heating section 2 is stopped.

The timer section 31 operates the heating section 2 for a predetermined period of time after activation.
A power supply circuit 34 that can limit the power supplied to the circuit and forms a predetermined DC voltage;
a timer time control circuit 35 that determines the timer time by performing a charging/discharging operation by applying a DC voltage formed by the switching circuit 36; and a diode 37 that bypasses the charging current to the capacitor 24 during each half cycle of the commercial AC voltage.

The flS circuit 34 rectifies the commercial AC voltage input via the TI plug 7 with a diode 38, and then forms a sufficiently stabilized DC voltage with a Zener diode 39 and a large capacitor 40.

By connecting a resistor 41 in parallel with the capacitor 40, the capacitor 40 is discharged at the same time as the input voltage is cut off to the power supply circuit 34, so that the voltage applied to the timer time control circuit 35 can be stopped early. ing.

The timer time control circuit a35 includes a capacitor 42 and a resistor 4.
Consisting of 3, 44, and 45, when main switch 50 is on,
Alternatively, when the quenching operation of the quenching switch 30 is stopped, charging of the capacitor 42 is started via the resistors 43 and 44 using the voltage output from the power supply circuit 34, and the capacitor 42 is discharged when the main switch 5 is turned off or when the quenching operation of the quenching switch 30 is operated.・The switching circuit 36 is connected to the resistor 4 by the charging current flowing to the capacitor 42 of the rm control circuit 35 during the timer.
The transistors 46 and 47 which are connected in Darlington are on/off controlled by the voltage drop across both ends of the transistor 47, and the collector and emitter of the transistor 47 are connected in parallel with both ends of the capacitor 24 of the control section 20 via a diode 37. There is. Therefore, during the ON operation of the switching circuit 36, both ends of the capacitor 240 of the control section 20 are connected to the diode 3.
7, the commercial alternating current voltage is short-circuited every half cycle to stop the control of the phase control element 21 and supply half the power to the heating unit 2 as would be the case when power control is performed using the temperature detection element 23.

Here, in the initial stage of starting the dryer or immediately after transitioning from a rapid cooling state to a heating state, for about 10 seconds, the temperature of the sensing element 23 itself is lower than the hot air temperature, and the resistance value of the element 23 maintains a low value. , the control unit 20 enters an uncontrolled state in which the heating unit 2 is energized for almost the entire period, and attempts to supply the heating unit 2 with power close to the limit of its power capacity. However, in this embodiment, by forcibly limiting the electric power supplied to the heating unit 2 to about half by the timer unit 31, the hot air is prevented from reaching an abnormally high temperature exceeding the control temperature. Even when there is a restriction, sufficiently large power is supplied to the heating unit 2, and the hot air temperature is prevented from dropping abnormally.

In addition, if the time during which electricity is not supplied to the heating section 2 is short, the temperature of the detection element 23 has not completely cooled down, and the time limit set by the timer section 31 may be shorter than the above-mentioned 10 seconds. In this embodiment, the capacitor 42 is discharged at a time constant corresponding to the temperature decreasing characteristic of the sensing element 23 at the same time as the power supply to the timer section 3J is cut off, and the capacitor 42 is completely discharged in an off time of about 30 seconds, for example. By setting the resistance value in such a manner that the temperature characteristics of the sensing element 23 itself are controlled, control can be performed in accordance with the temperature characteristics of the sensing element 23 itself.

[Effect of the invention 1] As described above, the present invention limits the power supply for a predetermined period of time at the initial stage of energization of the heating means, and sets the time limit so that it becomes shorter as the stop time before the start of energization is shorter. , even if the heating means is repeatedly turned on and off, abnormally high temperatures caused by the difference between the detected temperature and the hot air temperature are prevented, the power limit time is reduced as much as possible, and an appropriate temperature IYFI is maintained. It has excellent advantages such as being able to control the situation.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing the basic structure of the present invention. 2 and 3 show an example in which the present invention is applied to a dryer, FIG. 2 is a partially cutaway front view showing the overall shape, and FIG. 3 is an electric circuit diagram. 2...Heating section, 3...Blower section, 5...Main switch, 20...Control section, 23...Detection element, 30...Quick cooling switch, 31...Timer Department. Inventor: Michito Takahashi, Kenji Endo

Claims (1)

[Claims] 1. means for heating the air sent from the blowing means; means for detecting the temperature of the heated hot air; and controlling the electric power supplied to the heating means in accordance with the temperature detected by the detecting means. and a means that is activated at the start of energization to the heating means to limit the electric power supplied to the heating means for a predetermined period of time, the limiting time of the electric power by the limiting means being shorter than the time during which the energization to the heating means is stopped. An air blowing temperature control circuit characterized by setting the temperature so that the temperature becomes shorter as the temperature increases. 2. A means for heating the air sent from the blowing means, and a sensing element (23
), and a control unit that automatically controls the power supplied to the heating means by controlling the control angle for the phase control element (21) using the charging and discharging characteristics of the capacitor (24) connected in series with the detection element (23). (20), and the control unit (20) for a predetermined period of time after starting energizing the heating means
) a timer unit (31) that bypasses the charging current to the capacitor (24) every half cycle of the commercial AC power supply (8);
An air blowing temperature control circuit, characterized in that the bypass period by the timer section (31) is set to a predetermined set time as an upper limit, and is set to be shorter as the energization stop time to the heating means is shorter.