JPH02244583A - Mat-form electric heater - Google Patents

Abstract

PURPOSE:To make it possible to operate a piezoelectric sensor normally constantly by providing a noise sensor concurrently to the piezoelectric sensor, and subtracting the output of the noise sensor from the output of the piezoelectric sensor. CONSTITUTION:A piezoelectric sensor is formed by vacuum-evaporating aluminum electrodes 2 and 2 to both sides of a piezoelectric film 1, and laminating them by polyesters 4 through an adhesive 3. A noise sensor is formed by replacing the piezoelectric film in the piezoelectric sensor with polyester. In this mat-form electric heater, a piezoelectric sensor PS and a noise sensor NS are laid neighboring each other, and connected to an operation amplifier OP3 through operation amplifiers OP1 and OP2 respectively. From the output Va of the piezoelectric sensor PS including a noise, the output Vb of the noise sensor NS is differential-amplified through the operation amplifier 3, and an output Ve the noise component is removed is output.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application This invention relates to a rug-like electric heater such as an electric carpet or an electric room futon.

(b) Conventional technology Conventionally, this type of electric carpet or electric room futon has been equipped with a piezoelectric sensor (piezoelectric film)5, and the output of the piezoelectric sensor is amplified and changes in the output are used to detect people on top of the heater. It is determined whether or not the current exists, and the energization of the heater is controlled.

(C) Problems to be Solved by the Invention However, in conventional heaters equipped with piezoelectric sensors, large fluctuations in the power supply voltage of the heater and external noise superimposed on the heater are detected by the piezoelectric sensor. When the level was high, there was a malfunction in which the heater was judged to have a human body and the heater was energized even though there was no human body on top of the heater.

This invention was made with these circumstances in mind.Even if noise from the power supply or its battery is superimposed on the output of the piezoelectric sensor, the invention is designed to remove the noise component and allow the piezoelectric sensor to always operate normally. It provides an electric heater.

(d) Means for Solving the Problems The present invention provides a carpet-like electric heater in which an electric heater is embedded, which includes a strip-shaped piezoelectric film that generates voltage in response to pressure, and a strip-shaped piezoelectric film that is laminated on the top and bottom surfaces of the piezoelectric film. A piezoelectric sensor consisting of a cage, and a noise sensor consisting of a band-shaped insulating film and band-shaped electrodes laminated on the upper and lower surfaces of the insulating film, respectively, are attached to the rug adjacent to each other, and the inter-electrode voltage of the piezoelectric sensor is a calculation means for removing noise from the output of the pressure sensor and outputting the result by calculating the difference between the voltage between the electrodes of the noise sensor; and a control means for controlling energization to the electric heater in response to the output of the calculation means. This is a rug-like electric heating machine that is characterized by being equipped with.

(E) Effect If, for example, a human body is present on the rug ball, the piezoelectric sensor detects it and outputs it, but the noise sensor does not output it. Therefore,
The calculation means outputs a signal corresponding to the output of the piezoelectric sensor to the control means, and the control means receives the signal and controls energization of the heater.

In addition, when noise is superimposed on the output of the piezoelectric sensor, the noise sensor detects and outputs a similar noise signal, so when the difference between the two signals is calculated by the calculation means, the noise component is removed. .

Therefore, only the signal from the piezoelectric sensor is always input to the control means, and even if external noise is superimposed on the piezoelectric sensor, malfunction will not occur in controlling the energization of the heater.

(f) Examples The present invention will now be described in detail based on examples shown in the drawings. This invention is not limited by this.

FIG. 1 is a perspective view showing an electric carpet according to an embodiment of the present invention, where PS is a piezoelectric sensor disposed on the carpet CP, NS is a noise sensor disposed adjacent to the piezoelectric sensor PS, and CL is a noise sensor disposed adjacent to the piezoelectric sensor PS. A piezoelectric sensor PS and a noise sensor N are connected to the heating wire (not shown) buried in the car bella 1-CP.
This is a controller that receives the output from S and energizes it.

FIG. 2 is a cross-sectional view of the piezoelectric sensor applied to the embodiment shown in FIG. 4 is a polyester film laminated with the piezoelectric film 1;
3 is an adhesive layer inserted between them. The external dimensions of the piezoelectric sensor PS configured in this way are a thickness of 0. lzz,
The width will be 10xz.

FIG. 3 is a top view of the piezoelectric sensor shown in FIG. 2, in which a terminal block 6 is provided at one end and respective lead wires 7 from the electrodes 2 are fixed.

Further, the noise sensor NS is a piezoelectric sensor PS shown in FIGS. 2 and 3 in which the piezoelectric film 1 is replaced with a polyester film of the same size, and all other structures are the same.

FIG. 4 is a control circuit diagram of the embodiment shown in FIG. 1, in which the voltages generated in the piezoelectric sensor PS and the noise sensor NS are subjected to E-Bance conversion by operational amplifiers OPi and OP2, respectively, and then their respective outputs are converted by operational amplifier OP3. After being differentially amplified and waveform-shaped by a filter circuit PC, the voltage is divided by resistors R1 and R2, and input to the microcomputer MC via a resistor R3. The microcomputer MC receives the output from the resistor R3, determines whether there is a human body on the electric carpet CP, and outputs an energization control signal to the energization control circuit SC to the heating wire.

FIG. 5 is an example of a graph showing the waveform of the voltage input to the microcomputer MC via the resistor R3. When the human body on the electric carpet CP does not move, the voltage remains constant at 2.5V. When the human body moves, the voltage waveform changes due to the expansion and contraction of the piezoelectric film l of the piezoelectric PS. Therefore, the microcomputer NG determines that a human body is present on the electric carpet CP if the voltage becomes 3.3 V or higher and 1.6 V or lower within 2 seconds, and at that point. A signal is output to the energization control circuit SC to energize the heating wire for 20 minutes from then on.

FIG. 6 is a flowchart showing the details of its operation. The microcomputer MC detects the output of the resistor R3 every 0.1 seconds and detects that the detected voltage is 3.3 V or more or 1.6 V or less. If it is detected, the voltage will be reversed from that point on (if it first detects 3.3V or more, it will be 1.6V or less; if it first detects 1.6V or less, it will become 3.3V or more).
It is detected repeatedly up to 15 times every 0.1 seconds, and if the opposite voltage is detected during that time, it is determined that a human body is present on the electric carpet CP, and from that point on, the (minutes) energize the heating wire to heat the electric carpet CP. If the above-mentioned reverse voltage cannot be detected during the detection of the reverse voltage (up to 15 times), the microcomputer MC determines that there is no human body on the electric carpet CP, and every o, 1 second. Then, the operation of detecting input is repeated. That is, when the piezoelectric rim 1 expands and contracts due to the movement of the human body, and the signal shown in FIG. 5 is detected by the microcomputer MC, 1.
Therefore, it is determined that a human body is present on the electric carpet CPI.

By the way, when noise is superimposed on the output of the piezoelectric sensor PS as described above due to large fluctuations in the power supply voltage or noise such as radiated radio waves, the waveform of the output Va of the operational amplifier OI]1 becomes, for example, as shown in Fig. 7. become. On the other hand, noise sensor N
S is a structure in which the piezoelectric film 1 of the piezoelectric sensor PS is replaced with a normal insulating film, that is, a polyester film, as described above, and since it is arranged in parallel with the piezoelectric sensor PS, the piezoelectric film PS The captured noise is similarly captured by the noise sensor NS, and the output vb of the operational amplifier OP2 has a waveform as shown in FIG. Therefore, when the voltage Va is subtracted from the voltage vb in the operational amplifier OP3, the output voltage Ve of the operational amplifier OP3 becomes as shown in FIG. In other words, the voltage Vc is the voltage Va with the noise component removed. Therefore, even if a noise component is superimposed on the original detection voltage due to fraudulent expansion and contraction of the piezoelectric sensor PS, the heating wire of the electric carpet CP is energized without malfunction.

(g) Effects of the Invention According to this invention, even if noise is superimposed from the outside on the output of the piezoelectric sensor attached to the rug-like heater, the noise component is removed by the output of the noise sensor, so that the heating The presence or absence of a human body above is detected with high accuracy, and the heater is energized safely without malfunction.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing an embodiment of the present invention, FIG. 2 is a sectional view of a piezoelectric sensor used in the embodiment of FIG. 1, FIG. 3 is a top view of FIG. 2, and FIG. FIG. 1 is a control circuit diagram of the embodiment shown in FIG. 3 is a flowchart showing the operation of the section. MC...Microcomputer, SC...
...Electrification control circuit. CP...Electric carpet, PS...Piezoelectric sensor, NS...Noise sensor, OPI, CP2. CP3... operational amplifier,
FC...Filter circuit, R1, I (2, R3...Resistance, Figure ζI Figure ``J''

Claims (1)

[Scope of Claims] 1. A carpet-like electric heater in which an electric heater is buried, which includes a piezoelectric sensor consisting of a strip-shaped piezoelectric film that generates voltage in response to pressure, and strip-shaped electrodes laminated on both the upper and lower surfaces of the piezoelectric film. , a noise sensor consisting of a strip-shaped insulating film and strip-shaped electrodes laminated on the upper and lower surfaces of the insulating film is attached to the rug adjacent to each other, and the voltage between the electrodes of the piezoelectric sensor and the voltage between the electrodes of the noise sensor are The present invention is characterized by comprising a calculation means for removing noise from the output of the pressure sensor and outputting the result by calculating the difference between the two, and a control means for controlling energization to the electric heater in accordance with the output of the calculation means. A rug-shaped electric heater.