JPH02183725A - Heating device with pyroelectric sensor - Google Patents

Abstract

PURPOSE:To prevent the occurrence of leak between electrodes due to humidity, to prevent the occurrence of malfunction due to unnecessary noise, e.g. vibration, and to achieve stable control by a method wherein a pyroelectric substance formed on a metallic plate is molded by resin and a lead wire from the electrode is held. CONSTITUTION:A pyroelectric substance 2 is bonded on a metallic plate 1 of a pyroelectric sensor by means of an adhesive 3. A pair of electrodes 4 are formed to the pyroelectric substance 2, and lead wires 5 covered with resin are connected to the respective electrodes 4. The metallic plate 1 on the side, to which the pyroelectric substance 2 is adhered, the pyroelectric substance 2, the adhesive 3, the electrodes 4, and the lead wires 5 are molded by resin 6, and the lead wires 5 are securely held on the resin 6. Since the pyroelectric sensor responds to a thermal change, even when contaminants adhere on the surface of the metallic plate 1, a waveform is hardly changed. Holding of the lead wires 5 by means of the resin 6 causes reduction of the generation of noise due to piezoelectricity of the pyroelectric substance 2.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a pyroelectric sensor that utilizes the pyroelectric effect of a pyroelectric substance, and relates to a sensor that is applied, for example, to automation of reheating in a microwave oven.

BACKGROUND OF THE INVENTION Conventionally, there is a humidity sensor as shown in Figure 6 as a sensor used to automate reheating in a microwave oven.
It is composed of a sensor chip 19, a heater 20, a resin base 21, a mesh cover 22, and a terminal 23. Since the resistance value of the sensor chip 19 changes due to changes in humidity (steam generated from the food), the controller detects the cooking state of the food using the voltage divided by the reference voltage and the resistance (not shown). Ta.

When the heater 20 is used in a microwave oven, it is used to refresh the sensor chip 19 with heat to prevent it from becoming dirty due to food gas oil, etc., and the mensch cover 22 is used for wind protection and to save power of the reheater 20. It is used for this purpose.
(Nahanal Technical Rate Vol. 29
Nα3) Also, a case will be described in which a pyroelectric sensor 7 as shown in FIG. 7 is used to automate reheating of a microwave oven.

The pyroelectric sensor 7 includes a metal plate 1, a pyroelectric body 2, an adhesive 3, an electrode 4, and a lead wire 5. In a pyroelectric sensor, heated water vapor from food is passed through a metal plate 1 to a pyroelectric body 2.
Only when a thermal change is applied to the pyroelectric body 2, a pyroelectric current flows through the pyroelectric body 2 and is observed as a voltage if a resistor is connected to the outside. That is,
It is determined that the reheating of the food has ended when the water vapor from the food is successively applied to the pyroelectric body 2 as a thermal change.

The characteristics of the sensor are shown in Japanese Unexamined Patent Publication No. 112929/1983.

Problems to be Solved by the Invention However, when using the above-mentioned humidity sensor, gas and oil in the food adhere to the humidity sensor during cooking, reducing detection sensitivity. It is necessary to evaporate deposits on the humidity sensor using a heater for refresh heat treatment, which generates extra power and costs.In addition, since the voltage across the resistor is used as a control signal, the humidity sensor, which is each component Variations in resistance and power supply voltage lead to variations in control signals, making management difficult.

In addition, when using a pyroelectric sensor, the configuration is simpler than that of a humidity sensor, but the pyroelectric substance is ferroelectric, and pyroelectric (
When a temperature change is applied, a pyroelectric current is generated. ) and piezoelectricity (
Generates voltage when mechanical strain is applied. ) is shown. In other words, if the lead wire is in a free state when it is connected to the pyroelectric body, the vibration or shock applied to the lead wire will generate unnecessary voltage due to piezoelectricity at the lead wire connection point, and the control means sometimes incorrectly determined that reheating had finished.

Means for Solving the Problems In order to solve the above problems, a heating device with a pyroelectric sensor according to the present invention includes: a pyroelectric body connected to a metal plate or a conductive plate; a pair of electrodes; The lead wire led out from the electrode is molded with resin, and the lead wire is held with resin.

Function According to the present invention, the pyroelectric body has the function of reducing the influence of voltage generated by piezoelectricity due to vibration, distortion, etc.

EXAMPLE Hereinafter, an example of the present invention will be described based on the accompanying drawings.

FIG. 1 is a sectional view of a pyroelectric sensor 7 according to an embodiment of the present invention. A pyroelectric material 2 having a lead titanate-based and lead zirconate-based composition is bonded onto a metal plate 1 with an adhesive 3.

A pair of electrodes 4 are formed on the pyroelectric body 2, and resin-coated lead wires 5 are connected to each electrode 4, and a metal plate 1 and a metal plate 1 on the side to which the pyroelectric body 2 is bonded are connected to each other. , an adhesive 3, an electrode 4, and a lead wire 5 are molded with a resin 6, and the lead wire 5 is fixedly held on the resin 6.

FIG. 2 is a block diagram of the main body of a microwave oven having the pyroelectric sensor 7 of the present invention. a heating chamber 9 into which food 8 is taken out;
Magnetron lO1 exhaust section 11 for high-frequency heating of food 8
, pyroelectric sensor 7 provided in the exhaust section 11, magnetron IO
a cooling fan 12 for cooling the heating chamber, a duct 1-13 for blowing some of the air from the cooling fan 12 into the heating chamber, a filter 14 for filtering the output signal of the pyroelectric sensor 7, an amplifier 15 for amplifying the filter signal, and a control means. It consists of 16.

Automation of reheating of food 8 is performed as follows. Food 8 is placed in the heating chamber 9, and a magnetron 10 is placed inside the heating chamber 9.
A part of the cooling air is guided to the heating chamber 9 via the duct 13. A portion of the cooling air is shown by a solid arrow line 17, and water vapor generated from the food 8 is shown by a dotted arrow line 18. A portion of the cooling air 17 and water vapor 18 generated from the food 8 are transferred to the exhaust section 1.
1 and is discharged to the outside.

Here, Fig. 3 shows an example of the output voltage waveform regarding the signal and noise of the pyroelectric sensor 7 when 400 cc of water is heated. Fig. 3 shows the change over time until the water in the heating chamber 13 boils. The signal waveform shown in FIG. 4 is the result of spectrum analysis of this waveform.

As can be seen from FIG. 4, when warm water vapor hits the pyroelectric sensor 7, a large signal change is seen in the 0 to 2011z band. A is when the water in the heating chamber 13 has boiled, mouth is before boiling, and c is when the microwave oven is not energized.The difference between A and mouth is about 30 dB, and the signal level is a voltage of several Mv. It is. Therefore, a waveform passing through the filter 14 and the amplifier 15, which passes through the 0 to 10 seven bands, is observed as shown in FIG. The control means 16 controls ON/OFF of the magnetron 14 and the like based on this signal.

Furthermore, since the pyroelectric sensor responds to thermal changes, it was confirmed that even if dirt adhered to the surface of the metal plate 1, the waveform shown in FIG. 3 hardly changed.

Next, FIG. 5 is a comparison diagram of the signal level generated in the pyroelectric body 2 when vibration is applied when the lead wire 5 is held by the resin 6 and when it is not held. It can be seen that when the lead wire 5 is held by the resin 6 as shown, the noise due to the piezoelectricity of the pyroelectric body 2 is reduced.

Effects of the Invention As described above, according to the present invention, the following effects can be obtained.

(1) Since the pyroelectric body constructed on a metal plate is molded with resin and the lead wires from the electrodes are held, leakage between the electrodes due to moisture is prevented, and there is no malfunction due to unnecessary noise such as vibration. Stable control can be achieved.

(2) Since the lead wire is held with resin, it is possible to prevent the lead wire from peeling off from the electrode due to vibration.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of a heating device with a pyroelectric sensor according to an embodiment of the present invention, Fig. 2 is a configuration diagram of the main body incorporated in the device, and Fig. 3
The figure shows the output waveform of the pyroelectric sensor of the same device, Figure 4 shows the spectrum analysis of the output waveform of the same device, Figure 5 shows the output waveform of the pyroelectric sensor in response to vibration of the same device, and Figure 6 shows the conventional FIG. 7 is a block diagram of a conventional pyroelectric sensor. l...Metal plate, 2...Pyroelectric material, 3...
...Adhesive, 4...Electrode, 5...
Lead wire, 6...Resin. Agent's name Patent attorney Shigetaka Awano Haka 1 Meika 3 Figure Rocco SoS Kakusokuko 1st Ginnan, tC minute] Figure Kite envy song (Hz) Figure

Claims (1)

[Claims] a pyroelectric body bonded on a conductive plate; a pair of electrodes for extracting pyroelectric current generated in the pyroelectric body due to temperature change;
A heating device for a pyroelectric sensor, in which a lead wire led out from the electrode, the plate, the pyroelectric body, the electrode, and the lead wire are molded with resin, and the lead wire is held on the resin.