JPH0428191A - Control circuit of electric heater used in electric heating apparatus - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a control circuit for an electric heater used in electric heating equipment, and more specifically, the present invention relates to a control circuit for an electric heater used in an electric heating device. The present invention relates to a control circuit for an electric heater.

<Problems to be solved by conventional technology and inventions> In recent years, electric heating equipment has greatly improved its durability and has a longer service life.
There is a potential for unexpected failures to occur due to mechanical fatigue, etc.

For example, when heating devices such as electric carpets, electric blankets, electric hotpots, and electric stoves are used for a long period of time, situations may occur such as the heating wires of the electric heater short-circuiting or the temperature control function malfunctioning.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a control circuit for an electric heater that avoids the danger of long-term use and safely ends the product life of an electric heating device.

Means and Effects for Solving the Problems To achieve the above objects, the electric heater control circuit of the present invention includes a temperature sensor that measures the temperature of the electric heater, and a temperature reader that reads the temperature measured by the temperature sensor. a temperature setting means for setting the temperature by a user; a control means for controlling energization of an electric heater based on the temperature read by the temperature reading means and the temperature set by the temperature setting means; and use of an electric heating device. and a storage means for storing the cumulative time, and the control means is configured to set the temperature higher than the temperature set by the temperature setting means in the subsequent use of the electric heating device when the cumulative usage time stored in the storage means reaches a certain time tl. This controls the energization of the electric heater at a low temperature.

According to the electric heater control circuit configured as described above, when the electric heating equipment is used for a certain period of time or more, the electric heater is energized at a temperature lower than the temperature set by the temperature setting means, so the user can: Stop using the electric heating equipment because you think its functionality has deteriorated. Therefore, dangers associated with long-term use of electric heating equipment can be avoided.

In particular, the temperature range to be lowered when the accumulated usage time exceeds a certain time tl is the temperature that is often set on average by the temperature setting means (for example, "medium" when the set temperature is divided into high, medium and low).
It is preferable that the difference be greater than the difference between the maximum temperature that can be set by the temperature setting means. In this way, even if the user thinks that the function of the electric heating equipment has deteriorated and sets the temperature setting means to the maximum temperature, he or she will notice that the temperature is still lower than the temperature that was previously obtained. It is easy to judge the lifespan of electric heating equipment.

In addition, the control means controls the energization of the electric heater at a rate of a constant temperature per constant time every time the usage time of the electric heating device increases thereafter, when the accumulated usage time stored in the storage means reaches a certain time tl. The temperature may be lowered below the temperature set by the temperature setting means. According to this, if an electric heating device is used for more than a certain period of time, the temperature of the electric heating device will gradually drop, so the user can feel that the electric heating device has reached the end of its life without feeling unnatural. I start thinking.

<Example> Embodiments will be described in detail below with reference to the accompanying drawings showing embodiments.

FIG. 1 is a diagram showing a temperature control circuit for an electric carpet. Reference numeral 1 denotes a heating section of the electric carpet, which includes a sheathed heater 11 and a temperature sensor 12. The temperature sensor 12 is composed of a heat-sensitive wire whose impedance decreases when the temperature is high and whose impedance increases when the temperature is low. The temperature sensor 12 is connected to the main body temperature detection circuit 2, where temperature information is converted into an electrical signal and output. On the other hand, the temperature setting circuit 3 is a circuit that generates an electric signal corresponding to the temperature selected by the user using the slide resistor 31. The microcomputer 5 inputs an electric signal corresponding to the temperature detected by the main body temperature detection circuit 2 and an electric signal corresponding to the set temperature set by the temperature setting circuit 3, and controls the heater 11.
In order to control the temperature constant, the relay coil 7 is controlled to be turned on and off. 71 and 72 are relay switches driven by the relay coil 7. 4 is a power supply circuit that supplies power to the microcomputer 5.

Furthermore, an energization cumulative time storage device 6 is connected to the microcomputer 5 . This energization cumulative time storage device 6
is a circuit that stores the cumulative amount of time that the electric carpet has been used. For example, an E2FROM is used, which is a memory element on which information can be written and which does not lose information even if the external power supply is cut off.

The microcomputer 5 writes information into the energization cumulative time storage device 6 every time the electric carpet is used for a certain period of time to (for example, 10 hours), and the total written time is a certain time ttC, for example, 15.
000 hours), the temperature set by the temperature setting circuit 3 is stepped at a rate of T degrees (for example, 2 degrees) per operating time t2 (for example, 100 hours) than the temperature selected by the slide resistor 31. (see graph in Figure 2). Therefore, the user is initially satisfied with the heating at the set temperature, or as the user uses the electric carpet for a long period of time (i.e., beyond the usage time or tl), the user feels that the electric carpet gradually becomes less warm. So,
You will need to set the selected value of the slide resistor 31 to a high value, but if it still does not warm up even after setting it to the highest value,
When people feel that their equipment has reached the end of their lifespan, they begin to consider replacing it.

Note that the present invention is not limited to the above-mentioned embodiment, and for example, after the usage time tl, the temperature may be lowered linearly at a gradient of T degrees per hour t2 (see FIG. 3).

Alternatively, it may be lowered all at once once the usage time tl has been exceeded (see FIG. 4). In this case, the temperature range to be lowered can be set by the temperature that is often set on average by the temperature setting circuit 3 (for example, the temperature corresponding to "medium" when the set temperature is divided into high, middle, and low) and the temperature setting circuit 3. As already mentioned, it is preferable to set the temperature to be larger than the difference from the maximum temperature.

In addition, in the embodiments up to now, the usage time of the electric carpet or a certain period of time to is written in the energization cumulative time storage device 6 each time the electric carpet is used, but this is not incorporated in the temperature setting circuit 3 of the electric carpet. Each time a power switch is turned on, it may be assumed that the power switch is used for a certain period of time t□, and the corresponding time to is written.

Various design changes can be made without changing the gist of the invention.

<Effects of the Invention> As described above, according to the electric heater control circuit of the present invention, when the electric heating device is used for more than a certain period of time tl, the user thinks that the heating function has deteriorated and stops using the electric heating device. Abort. Therefore, the dangers associated with long-term use of electric heating equipment can be avoided and the product life can be ended safely.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of an electric carpet incorporating the electric heater control circuit of the present invention, and FIGS. 2 to 4 are graphs showing changes in set temperature. ...Body temperature detection circuit, 3.Temperature setting circuit, 5.Microcomputer, 6.Cumulative energization time storage device, 1.Heater, 12.Temperature sensor

Claims (1)

[Claims] 1. Temperature sensor (to measure the temperature of the electric heater (11)
12), a temperature reading means (2) for reading the temperature measured by the temperature sensor (12), a temperature setting means (3) for setting the temperature by the user, and a temperature read by the temperature reading means (2). control means (5) for controlling energization of the electric heater based on the temperature set by the temperature setting means (3);
Storage means (6) for storing the cumulative usage time of electric heating equipment
The control means (5) is configured to set the temperature using the temperature setting means (3) in the subsequent use of the electric heating device when the accumulated usage time stored in the storage means (6) reaches a certain time tl. An electric heater control circuit used in electric heating equipment, characterized in that it controls energization of the electric heater at a temperature lower than the temperature.