JPH0812790B2 - Electric heater - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Field of Industrial Application> The present invention relates to an electric heater such as an electric carpet or an electric cushion.

<Prior Art> A conventional electric heater will be described by taking an electric carpet as an example.

The conventional electric carpet is an electric carpet provided with a piezoelectric film, and the output of the piezoelectric film is periodically changed by a microcomputer (hereinafter, abbreviated as a microcomputer) via an impedance conversion circuit and a filter circuit. By detecting, it is determined whether or not there is a person on the electric carpet, and the heater is turned on only for a certain period of time from the time when it is determined that there is a person.

<Problems to be Solved by the Invention> In such a case, if a large fluctuation of the power supply voltage or other strong noise is generated outside, a voltage due to the influence may be generated in the piezoelectric film. If the noise level is above a certain level, there is a problem that it is determined that there is no person on the electric carpet.

<Means for Solving the Problems> In order to solve the above problems, the electric heater of the present invention has a piezoelectric film such as poly (fucca vinylidene) disposed in the main body of the electric heater, and a human body is placed on the main body. When an animal such as moves, the voltage generated from the piezoelectric film is detected by a microcomputer via an impedance conversion circuit and a filter circuit, and it is determined whether or not there is a person on the main body. If judged, in an electric heater capable of turning on the heater only for a certain period from that point, a switching element inside the control circuit and a noise detection electrode for detecting noise from the outside are added to the piezoelectric film. Arranged,
A switching element inside the control circuit and a noise detection circuit for detecting noise from the outside are provided by the electrodes, and when the output voltage of the noise detection circuit exceeds a certain value, the signal from the filter circuit to the microcomputer is cut off for a predetermined time. A masking circuit is provided.

<Operation> In the electric heater of the present invention, when noise from the switching element in the control circuit or from the outside is directly applied to the piezoelectric film or is added to the piezoelectric film by the heater, noise detection is performed via the noise detection electrode of the piezoelectric film. When the circuit detects the noise and the output voltage of the noise detection circuit exceeds a certain value, the masking circuit cuts off the signal from the filter circuit to the microcomputer, which causes the microcomputer to erroneously display on the main body of the electric heater. Eliminate the possibility that there is a person.

<Example> An example of the present invention will be described with reference to Figs. 1 to 8. FIG. 1 shows a sectional view of a piezoelectric film provided on an electric carpet. The thickness and width of the piezoelectric film are about 0.1 mm and 10 mm, respectively, and the voltage is generated by the pressure. The electrode 2 is on one side of the piezoelectric resin 1 (polyfucca vinylidene 0.03 mm), the electrode 2 on the other side, and noise detection. The electrode 3 is formed by vapor deposition of aluminum to form the electrode 2, and the outer surface of the electrode 2 is laminated with the polyester film 5 using the adhesive 4. FIG. 2 is a front view of the piezoelectric sensor 6, showing the electrodes 2 of the piezoelectric film.
The noise detection electrode 3 is electrically connected to each lead wire 7 by a terminal portion 8. FIG. 3 is a circuit configuration diagram of the present invention. The voltage generated in the piezoelectric sensor 6 by the movement of the person is waveform-shaped by the impedance conversion circuit 9 and the filter circuit 10 so that the generated voltage (several Hz component) due to the movement of the person can be well detected. The output of the filter circuit 10 is input to the microcomputer 13 via the resistors 11 and 12. Microcomputer 1
The detection input of 3 is normally about 2.5 V when there is no movement of the person, but when the person moves, the voltage waveform as shown in FIG. 4 appears due to the extension and return of the piezoelectric film. In this voltage waveform, if both of the states of about 3.3v or more and about 1.6v or less occur within about 2 seconds, the microcomputer 13 determines that there is a person on the electric carpet, and from that time point. 20 minutes only
The heater control circuit 14 for turning on the heater is energized.

FIG. 5 is a flow chart of the microcomputer 13
13 detects the detection input about every 0.1 seconds and the detection voltage is about 3.3.
If it detects that the voltage is higher than or equal to v or lower than about 1.6v, the voltage is reversed from that point (1.6v or lower if about 3.3v or higher was detected last time, 3.3 if 1.6v or lower was detected last time. v)) is detected every 0.1 seconds up to 15 times, and if a reverse voltage is detected during that time, it is determined that there is a person on the electric carpet, and the heater is heated for 20 minutes from that point. At the same time that the control circuit 14 is activated, the detection input of the microcomputer 13 is detected about every 0.1 seconds.

If the reverse voltage cannot be detected while sending the reverse voltage (up to 15 times), it is determined that no one is on the electric carpet, and the detection input of the microcomputer 13 is detected about every 0.1 seconds. It is a system that returns to operation.

Therefore, the movement of a person causes the piezoelectric film to expand back, which causes the detection input of the microcomputer 13 to rise above 3.3v and below 1.6v within about 2 seconds as shown in Fig. 4. It is determined that there is a person on the carpet.

However, a voltage may be induced in the piezoelectric film not only by the movement of a person or an animal, but also by noise generated by a switching element inside the control circuit or noise such as radiated radio waves.

Therefore, in the present invention, noise is detected by the noise detection circuit 16 from the noise detection electrode 3 of the piezoelectric film 5 via the capacitor 15, and the output voltage thereof is the upper limit value (8v) or more or the lower limit value (4v) or less by the window comparator. If so, the transistor 18 is turned on for a certain period from that point, and the detection input of the microcomputer 13 to which the voltage obtained by dividing the output voltage of the filter circuit 10 by the resistors 11 and 12 is applied is forced to exceed Lo (over 3.3v). Absent)
I am using a masking circuit 17 that says.

Therefore, when the output voltage of the filter circuit 10 reaches the human body detection level (8v or more or 4v or less) as shown in FIG. 6 due to noise, the output voltage of the noise detection circuit 16 becomes the upper limit as shown in FIG. Since the value (8v) or more or the lower limit value (4v) or less, the masking circuit 17 must be activated and the transistor
Since 18 turns on, the detection input of the microcomputer 13 becomes Lo as shown in Fig. 8 and it does not exceed 3.3v.
Eliminates erroneous operations such as noise that determines that there is no person on the electric carpet.

<Effects of the Invention> Since the electric heater of the present invention is configured as described above, no malfunction occurs due to noise or the like, and the heater can be energized only when a person is present on the electric carpe body. When there is no electricity, the electricity to the heater is stopped after a certain period of time, and wasteful power consumption due to forgetting to turn off the electricity can be prevented.

Further, the noise added to the piezoelectric film can be easily detected only by providing the piezoelectric film with the noise detection electrode.

[Brief description of drawings]

1 to 3 and 5 show an embodiment of the present invention. FIG. 1 is a sectional view of a piezoelectric film, FIG. 2 is a front view of a piezoelectric sensor, and FIG. 3 is a circuit configuration. 4 and 5 are voltage waveforms of the detection input of the microcomputer 12 that appear when a person moves on the electric carpet, and FIG. 5 is a flowchart of the microcomputer 12. FIG. 6, FIG. 7, and FIG. 8 respectively show the output of the filter circuit 9 and the noise detection circuit which appear due to noise.
16 is a voltage waveform of 16 outputs and a detection input of the microcomputer 12. In the figure, 1: piezoelectric resin, 2: electrode, 3: noise detection electrode, 6: piezoelectric sensor, 9: impedance conversion circuit, 10: filter circuit, 13: microcomputer, 16: noise detection circuit, 17: masking circuit.

Claims (1)

[Claims] 1. A piezoelectric film such as polyfucca vinylidene is provided in a main body of an electric heater, and when an animal such as a human body moves on the main body, a voltage generated from the piezoelectric film is converted into an impedance conversion circuit and a filter circuit. The electric heating that can turn on the heater only for a certain period from that point if it is determined that there is a person on the main body by detecting with a microcomputer via In the container, a switching element inside the control circuit and a noise detection electrode for detecting noise from the outside are arranged on the piezoelectric film, and the switching element inside the control circuit and the noise from the outside are detected by the noise detection electrode. A noise detection circuit is provided, and when the output voltage of the noise detection circuit exceeds a certain voltage, the filter circuit outputs a predetermined time to the microcomputer. An electric heater characterized by being provided with a masking circuit for cutting off signals.