JP2538055B2 - Cooker with pyroelectric steam sensor - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of mounting a pyroelectric steam sensor for detecting high temperature steam, hot air, etc., when the cooker is used.

2. Description of the Related Art Since a conventional sensor of this type is often used for the purpose of detecting boiling in a cooking device such as a high frequency heating device, a technique related to the high frequency heating device will be described here.

First, as a typical example, there is an absolute humidity sensor. 8th
The absolute humidity sensor shown in the figure includes a sensor chip 43, a heater 44, a resin base 45, a mesh cover 46, and a terminal 47. Since the resistance value of the sensor chip 43 changes depending on the humidity, the cooking state is detected by comparing the reference voltage with the voltage determined by the resistance value. When the absolute humidity sensor is used in a high-frequency heating device, the heater 44 is for refreshing because the sensor chip 43 is contaminated by food gas, oil, etc., and the mesh cover 46 is for windproof and saves the heater 44. It is used for electricity conversion. (National Technical Report Vol.29 No.3 JAN1983) Fig. 9 shows a conventional high frequency heating device with an absolute humidity sensor. In the case of the absolute humidity sensor, the moisture in the food boils and the humidity changes rapidly from a decrease to an increase. Therefore, the end of cooking can be determined by detecting this point. Based on this, as shown in FIG.
The change in the resistance value of the absolute humidity sensor 48 is detected by dividing the voltage of the reference voltage power supply 49 with the resistance 50 to control the device. 19 is a magnetron. (For example, JP-A-53-77
In addition to the absolute humidity sensor, there is a pyroelectric vapor sensor. Generally, a pyroelectric vapor sensor has a structure as shown in FIG. 10, for example, and a lead portion 4 is attached to a metal plate 2 and an electrode 14. (For example, Japanese Unexamined Patent Publication No. 62-37624) Problems to be Solved by the Invention However, when the humidity sensor is used as described above, the gas or oil in food adheres to the humidity sensor during cooking and the detection sensitivity decreases. Therefore, it is necessary to evaporate the adhering substances of the humidity sensor with a heater for refresh heat treatment or the like for each cooking, which causes a problem that extra power and cost are generated.

Although there is a method of using a pyroelectric vapor sensor instead of the humidity sensor, since the lead portion 4 is attached to the electrode 14, the electrode 14 is separated from the metal plate 2 when the lead portion 4 is pulled or bent. , There was a problem of peeling.

Therefore, an object of the present invention is to prevent electrode peeling due to pulling or bending of leads.

Means for Solving the Problems In order to achieve the above object, the present invention employs a pyroelectric vapor sensor and fixes the lead to a part of the cooker body.

Action In the cooker with a pyroelectric steam sensor of the present invention, since the leads are fixed to the cooker body, a force (for example, pulling or bending) that stresses the root of the leads (that is, the bonding portion with the electrode) is generated. This prevents the pyroelectric steam sensor from being destroyed, and the cooking device with the sensor has high reliability.

Embodiment An embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a configuration diagram when the pyroelectric vapor sensor is fixed to the cooker body. The pyroelectric vapor sensor 1 has a plate body 2 having heat conductivity fixed to a guide 3, and the lead 4 has a guide 3
Is adhered to a part of the adhesive with the adhesive 5. For this reason, the movement of the lead 4 is restricted, and stress is less likely to be applied to the adhesive portion 6 with the electrode. As an actual air flow, hot air (or steam) 8 passing through the hot air passage 7 is mixed with cold air 10 passing through the cold air passage 9 to cause a thermal change in the heat conductive plate body 2 of the pyroelectric steam sensor 1. To give mixed air 11 and mixed air passage
Leave 12.

In FIG. 2, the pyroelectric vapor sensor 1 is viewed from above (a).
The figure and the figure (b) showing a section are shown, and an external perspective view is shown in FIG.

The pyroelectric vapor sensor 1 has a ceramic 15 having a pair of electrodes 13 and 14 facing each other and a lead portion 4 led out from the pair of Ag electrodes 13 and 14 on a plate body 2 having heat conductivity. One of the electrodes 13 is a folded electrode extending over part of the first surface and the second surface of the ceramic 15, and the other electrode 14 is arranged on the second surface of the ceramic 15. The pyroelectric element (including the electrodes 13 and 14 and the ceramic 15) is kept in thermal contact with the metal plate 2 with an adhesive 16 such as a silicon-based material. Although it also serves to fix the lead portion 4, the main purpose is to cover the pyroelectric element with a coating agent 17 such as a silicon-based material for the purpose of preventing moisture.

The actual operation will be described. When steam with heat hits the metal plate 2, heat is transferred in the order of the metal plate 2-> the adhesive 16-> the pyroelectric element ceramic 15, and the polarization current is generated by the pyroelectric effect according to the heat transmitted by the pyroelectric element. appear. The presence / absence of steam input to the plate body 2 having heat conductivity can be determined according to the polarization current.

FIG. 4 is a high-frequency heating device with a pyroelectric vapor sensor showing an embodiment of the present invention.

The output of the pyroelectric vapor sensor 1 enters the controller 18, and the controller 18 controls the operation of the radio wave radiating section 19 and the cooling fan 20 according to the signal.

Food 22 is arranged in the heating chamber 21, and a part of the cooling wind of the radio wave radiation unit (magnetron in this case) 19 is cooled by the cooling fan 20.
Is introduced into the heating chamber 21 via the duct 23. A part of the cooling air is shown by a solid arrow line 24, and air containing water vapor and oil generated from food is shown by a solid arrow line 25. The air containing the steam and oil generated from the cooling wind and the food is sent to the outside from the louver 28 of the body cover 27 through the exhaust unit 26.

On the other hand, there is another sucking hole 29 in the heating chamber 21, and a part of the steam 30 passes through the sucking hole 29, transfers heat to the pyroelectric steam sensor 1, and is then sent to the outside from the louver 31 of the body cover 27. It

The cooling air 32 from the cooling fan 20 is also used for cooling the pyroelectric steam sensor 1 and sucking out a part of the steam 30, and the source of the cooling air is the external air 33. Is taken in through the hole 34 in the body cover 27.

With the above configuration, the high-frequency heating device with a pyroelectric vapor sensor detects the cooking finish state. Of course, the same principle can be used in other cookers.

FIG. 5 shows an output obtained when the pyroelectric vapor sensor 7 is used in a high frequency heating device as a frequency characteristic with a spectrum analyzer. A is the signal before boiling, and A is the signal after boiling. As you can easily imagine from this waveform, low pass filter (LPF) is used to increase S / N.
Is better to use.

FIG. 6 is a block diagram showing the inside of the controller 18.
As described above, the pyroelectric vapor sensor 1 is subjected to heat change by boiling vapor or the like and generates a polarization current. Inside the controller 18, a short resistance 35 for extracting the polarization current as a voltage value, and temperature characteristic correction (stabilization) of the pyroelectric vapor sensor 1
There is a capacitor 36 for use, and the signal is filtered by LPF37 (cutoff 4HZ) as described in FIG. 5, amplified by amplifier 38, rectified by rectifier 39, and microcomputer 40
The control signal is sent to the heating means 41 such as the heater of the cooking device or the magnetron of the microwave oven by determining whether the detection level is. (Of course, it is also possible to control without using a microcomputer.) FIG. 7 shows another embodiment. The fixing of the lead 4 is performed by the fixing tool 42.

As described above, according to the present invention, the pyroelectric steam sensor is fixed to the cooker main body so that pulling or bending of the lead does not occur during the assembly process or transportation, and the root of the lead ( That is, stress is not applied to the electrode).
Since failure such as element peeling and electrode peeling can be prevented, there is an effect that a highly reliable sensor and a cooker with a sensor can be provided.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an essential part of a pyroelectric steam sensor according to an embodiment of the present invention fixed to a cooking device, FIG. 2a is a plan view of the pyroelectric steam sensor, and FIG. Fig. 3 is a perspective view of the same, Fig. 4 is a sectional view of the pyroelectric steam sensor when used in a high-frequency heating device, and Fig. 5 is a frequency characteristic diagram of the output of the pyroelectric steam sensor, Fig. 6 Is a block diagram of the controller, FIG. 7 is a cross-sectional view of essential parts showing another embodiment, FIG. 8 is a perspective view of a conventional absolute humidity sensor, and FIG. 9 is a high-frequency heating device with a conventional absolute humidity sensor. FIG. 10 is a configuration diagram of a conventional pyroelectric vapor sensor. 1 ... Pyroelectric vapor sensor, 3 ... Main body guide, 4 ... Reed, 18 ... Controller, 19 ... Heat source (radio wave radiation part).

Front page continuation (72) Inventor Kimiaki Yamaguchi 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) Reference JP-A-2-183725 (JP, A) , U)

Claims (1)

(57) [Claims] 1. A pyroelectric vapor sensor having a heat conductive plate, a ceramic having a pair of electrodes on the plate, a lead led out from the plate or the electrodes, and a heat source inside. A cooker with a pyroelectric steam sensor, wherein the lead of the pyroelectric steam sensor is fixed to a part of the cooker main body.