JPS5833453B2 - High frequency heating device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a high frequency heating device that controls the heating temperature of food by detecting radiation emitted from the food.

When a pyroelectric infrared detector is used as a radiation detector, the detection element that has a pyroelectric effect generally has a voltage effect.

In high-frequency heating equipment, the vibrations of the magnetic tube cooling fan motor and the detector chopper generate a noise voltage proportional to the frequency of vibration as a piezoelectric effect.

An object of the present invention is to provide a high-frequency heating device that can separate the noise signal and the food temperature signal and reliably extract only the temperature signal.

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

In Figures 1 to 3, 1 is the main body of the high-frequency heating device, 2
2 is an oven, 2a is an oven top plate, 2b is an oven side plate, 3 is a magnetron tube that oscillates high frequency waves, 4 is a front operation panel, and 5 is a food product 7 placed on a turntable.

8 is a fan for cooling the magnetron tube 3; 9 is a motor for driving the fan 8; the air that has cooled the magnetron tube 3 flows into the oven 2 through an air guide 10.

The air shunted by the fan 8 passes through the guide 11, flows into the infrared detector 120 cover 13, and flows out into the oven 2 through the infrared detection hole 14 of the oven top plate 2a.

This means that water vapor, oil smoke, etc. from the food 7 can be detected by the infrared detector 12.
This is to prevent it from entering the inside of the body and reducing the detection ability.

15 is a step-up transformer for boosting the voltage to a voltage at which the magnetic tube 3 can operate; 16 is a voltage doubler rectifying the voltage boosted by a high-voltage capacitor together with a diode (not shown), and the magnetic tube 3
It is intended to supply

Reference numeral 17 denotes a door arm, and when the door (not shown) is opened, a contact point of a door switch 18 is opened to remove the high frequency power supply and stop high frequency oscillation.

Reference numeral 19 denotes a door arm roller which allows the door arm 17 to move smoothly.

Reference numeral 20 denotes a stand that receives the door arm roller 19.

21 is a bottom plate that supports the entire main body of the high-frequency heating device.

Numeral 22 is a door spring that pulls between the door arm 1T and the bottom plate 21, so that the door does not open easily.

To explain the drive of the turntable 5, the fan 8
A pulley 23 is attached to the opposite side of the blade.

Pulley 23 and pulley 24 are connected by a belt 25 to transmit rotational force.

The pulley 24 transmits the rotational force to the reduction gear box 27 by the shaft 26, and the rotational force shaft 2 is reduced in speed.
8 to the pulley 29.

Pulley 29 and pulley 30 are connected by a belt 31.

Magnets 32a, 32b fixed to the pulley 30 and magnets 33a, 33 fixed to the turntable 6
b attract each other, and the rotational force of the IJ-30 is transmitted to the turntable 6.

Next, the infrared detector 12 will be explained.

Infrared rays from the food 7 enter through the hole 14 in the oven top plate 2a, are reflected by the reflecting mirror 34, pass through the hole 36 in the chopper 35, and enter the infrared detector 12.

To explain the configuration and operation of changing the direction of reflection of infrared rays by the reflector 34, power is transmitted from the fan motor 8 to the pulley 24 via the pulley 23 and the belt 25, and the power is transmitted from the fan motor 8 to the pulley 24 provided adjacent to the pulley 24. Power is transmitted from the rotation to the pulley 39 via the belt 38, and the cam 4 provided adjacent to the pulley 39
00 rotation causes the lever 41 to reciprocate in the direction of arrow A.

The lever 41 is fixed to a shaft 42 supporting the reflecting mirror 34, and as the lever 41 moves back and forth, the reflecting mirror 34 rotates and moves back and forth.

By rotating and reciprocating the reflecting mirror 34, the central force of the turntable 6 is scanned in the direction of the outer periphery, from the outer periphery through the center to the opposite outer periphery and from this outer periphery in the opposite direction toward the center.

FIG. 5 shows a scanning trajectory obtained by combining the scanning by the reflecting mirror and the scanning by 60 rotations of the turntable.

In Fig. 5, the mark indicates that the reflection mirror 34
When the reflector 34 makes l reciprocations, it shows the locus of the scanning center, next, the circle mark shows the locus of the scanning center when the reflecting mirror 34 makes the next l reciprocations, and the third one shows the locus of the scanning center, and the third mark shows the locus of the scanning center when it makes l reciprocations. , the entire turntable will be scanned in the same way.

The chopper is directly connected to the shaft of the fan motor, -8, and has a plurality of holes 36 around it.

Therefore, the scanning frequency is the product of the number of rotations of the fan motor 90 and the number of holes 36 in the chopper 35.

·, ○, × in Figure 5. The mark indicates the position of the temporal center of the hole 36 of the chopper 35.

In addition, in the above-mentioned scanning method, the entire area is scanned when the turntable rotates 1/2, but it is also possible to scan the entire area during one rotation.

In other words, in the first half-turn, it scans the locus indicated by the first * mark, the third locus indicated by the × mark, the fifth, seventh, etc., and in the next half-turn, it scans the second trace indicated by the × mark. Locus indicated by marks, 4th, 6th...
By scanning..., the entire area can be scanned in one rotation.

The infrared detector 12 is designed to output a signal proportional to the difference between the amount of infrared rays from the food 7 and the amount of infrared rays from the chopper 35.

As the chopper 35 rotates, a signal proportional to the temperature difference between the food 7 and the chopper 35 is generated.

The high frequency output can be controlled by the peak value or average value of this signal.

The features of the present invention are that the infrared detector 12 is attached to the main body of the apparatus via a vibration isolating member, and that the output signal of the infrared detector 12 is extracted through a filter.

That is, as shown in FIGS. 1 and 4, the infrared detector 12 is mounted on the oven top plate 2a with vibration-proof rubber 43 and screws 44.

This effect will be explained below. If there is no anti-vibration rubber 43, the fan motor 9, chopper 3
Due to the vibration caused by 5, a high frequency component and a low frequency component appear as an output signal of the infrared detector 12, as shown in the graph of FIG. 6a.

In this case, the temperatures of the food and the chopper 35 are the same, and the temperature signal from the food is zero.

If the anti-vibration rubber 43 is used, when it is attached to the oven top plate 2a, depending on how the natural frequency of the anti-vibration rubber is selected, the high frequency component may be reduced (as shown in Figure 6, c), or the low frequency component may be reduced. will disappear at the same time.

Furthermore, if the food temperature signal frequency is selected at a frequency different from the noise frequency for the noise caused by vibration as shown in FIG. By processing the output signal of the infrared detector 12 with an electric filter, only the temperature signal frequency component of the food can be reliably extracted.

For example, the high frequency component of the noise is 1KH2° and the low frequency component is 60°.
, 120H2, the food temperature signal is 500H
If it is set to 2, the filter characteristics will be 450H2.
Hereinafter, it is sufficient to set the frequency such that frequencies of 550H2 and above are greatly attenuated.

To explain this filter circuit configuration with reference to FIG. 7, the output signal from the infrared detector A is transferred to the filter B
Then, only the food temperature signal frequency component is sent to the next chopper chamber correction circuit C, and correction is performed so that the signal does not change even if the chopper temperature changes.

Further, this output signal is compared with the next set temperature by a comparison circuit and sent to the control circuit E, and the high frequency generator F is controlled by this output.

By processing and extracting the signal in such a circuit, noise caused by vibration can be eliminated in conjunction with the action of the vibration isolating rubber 430.

As is clear from the above description, the high-frequency heating device of the present invention has a radiation detector attached to the main body of the device via a vibration isolating member, and the output signal of the detector is processed by a filter. Therefore, the noise signal can be removed from the detector output and only the food temperature signal can be extracted, resulting in a unique effect.

[Brief explanation of drawings]

FIG. 1 is a perspective view of the main parts inside a high-frequency heating device according to an embodiment of the present invention, FIG. 2 is a cross-sectional view of the main parts of the same device, FIG. Figures a and b are side sectional views and bottom views of the infrared detector mounting part, Figure 5 is a diagram showing the scanning locus of the infrared detector, and Figures 6 a, b, and c.
7 is a signal waveform diagram for explaining the present invention in detail, and FIG. 7 is a block diagram showing the processing procedure of the detection signal of the apparatus of the present invention. 12... Infrared detector, 43... Anti-vibration rubber, B... Filter.

Claims (1)

[Claims] 1. In a high-frequency heating device that detects radiation emitted from food and controls high-frequency output, a radiation detector is attached to the main body of the device via a vibration-proofing member, and the output signal of the radiation detector is extracted through a filter. A high frequency heating device characterized by: