JPS6136359B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heating source control device for a cooking device such as a microwave oven.

By the way, if you look at conventional devices like this, for example, there is a device shown in U.S. Patent No. 3,988,930 that uses a temperature-sensitive probe with a built-in temperature-sensing element such as a thermistor at the tip to touch food. The temperature information signal output by the temperature sensing element is guided to a control circuit installed outside the oven via a cable led out from the temperature sensing probe, and when the temperature of the food reaches a predetermined value, the control circuit There is a structure that stops the drive of the magnetron, which is the heating source.

However, this type of device has the disadvantage that it cannot be applied to microwave ovens that heat food while rotating it on a turntable, such as modern microwave ovens, although it is necessary to consider the thermal effect on the cable. It was hot.

Therefore, in order to solve the drawbacks of this conventional device, there is a patent application filed by the present applicant on January 20, 1972, ``Temperature Control Device'', etc., in Japanese Patent Application No. 52-5546. The temperature information signal output from the temperature sensing element built into the tip of the probe excites the ultrasonic oscillator built into the probe to oscillate ultrasonic waves, which are then received by a receiver installed on the oven side. When the temperature of the food reaches a predetermined value, the control circuit stops driving the magnetron.

Of course, this device is so-called wireless and can be applied to a device that heats food while rotating it with a turntable, which solves the drawbacks of the device shown in the above US patent, but the above ultrasonic oscillator Since it is constantly driven, it has the disadvantage of extremely rapid battery consumption.

The present invention was devised in view of the drawbacks of the conventional devices, and is an oscillation circuit provided within the thermosensor probe in order to prevent as much as possible the consumption of the battery housed within the thermosensor probe for driving the oscillation circuit. The device is intended to be driven intermittently using an oscillation induction signal output from an operation control circuit provided on the oven side.

Hereinafter, one embodiment will be described in detail with reference to the accompanying drawings.

FIG. 1 is a block diagram of a microwave oven equipped with a device according to the present invention, in which 1 is an oven, equipped with a magnetron Mg as a heating source on the ceiling surface and a turntable 2 on the internal bottom surface. .
Therefore, in this oven, dielectric heating is performed by the magnetron Mg while rotating the food F on the turntable 2.

3 is a temperature-sensitive probe, and as shown in FIG. 2, it has an insertion tube section 4 made of a thin metal tube with one end pointed at its tip, and a fitting section into which the other end of the insertion tube section 4 is fitted. 5a and an antenna attachment portion 5 at the other end.
b, and a handle tube portion 5 made of a metal tube with a board attachment portion 5c provided in the center thereof.

The temperature sensing probe 3 supports a resonator 6 as a temperature sensing element (a crystal resonator, a ceramic resonator, etc. whose resonance frequency changes depending on the ambient temperature) within the pointed end portion of the insertion portion 4. Further, a printed circuit board 7 and a battery 8, which are equipped with a transmitting circuit (described later), are fixed to the board attachment part 5c in the handle tube part 5, and a second antenna 9 is attached to the antenna attachment part 5b, Further, a chain structure 5d is formed in the handle tube 5 to attenuate the microwaves that enter through the antenna attachment part 5b, and the lead wire 10 connects the oscillation circuit of the vibrator 6 and the printed circuit board 7. This oscillation circuit and the second antenna 9 are connected by wires 11, respectively. Also, the handle tube part 5
A protective film 12, including the antenna 9, is formed on the outer surface of the antenna 9 by molding rubber, resin, or the like. 13
is a reed switch for the oscillation circuit attached to the wall inside the handle tube part 5,
Turns on or off by sliding operation of a switch actuator 15 made of a magnet that is slidably supported in a support groove 14 provided in the protective film 12 so as not to come off.
I'm starting to do that.

The temperature-sensitive probe 3 configured as described above is inserted into the food F using its insertion tube section 4, and the transducer 6 is inserted into the food F.
Accordingly, the temperature rise of the food F is detected, and this temperature information is converted into an electrical signal by the oscillation circuit, and the electrical signal is radiated from the antenna 9 as a carrier wave. That is, the temperature sensing probe 3, the vibrator 6, the oscillation circuit, etc. constitute a so-called temperature sensing device.

By the way, the above-mentioned oscillation circuit consists of an electric circuit as shown in FIG. 3, and the above-mentioned reed switch 13 incorporated in this circuit is
When the second antenna 9 receives an oscillation-induced signal f _A transmitted through the first antenna 16 installed on the ceiling of the oven 1 from an operation control circuit provided on the oven side, which will be described later, in the ON state, Since the voltage at the non-grounded end of the second antenna 9 becomes lower than the voltage between the base and emitter of the diode D ₁ and the transistor Q ₃ , the transistor Q ₃ becomes conductive.

Along with this, the transistors Q ₂ and Q ₁
are sequentially turned on, and the transmission power of the battery 8, which is the power source of the oscillation circuit, is applied to the oscillation circuit section 17, which is mainly composed of the transistor _Q4 , and the amplifier circuit section 18, which is mainly composed of the transistor _Q5 . In conjunction with this, the oscillation circuit unit 17 oscillates due to the vibration of the vibrator 6 detecting the food temperature, and the oscillation output is amplified by the amplifier circuit 18 and then becomes the food temperature information signal f. _B is transmitted from the second antenna 9 toward the first antenna 16. and,
Such an oscillation operation is performed every time the oscillation induced signal f _A is received by the antenna 9. In terms of each oscillation operation, it starts with the reception of the signal f _A , and then the capacitor C ₁ and the resistor R ₁ Charge is accumulated in the capacitor C _{1 of} the time constant circuit composed of
This continues until the base voltage of the battery 8 becomes higher than the base voltage of the transistor Q1, and accordingly, the transistor _Q1 becomes non-conductive and the power supply of the battery 8 to the oscillation and amplification circuit sections 17 and 18 is stopped.

By the way, regarding the above-mentioned vibrator 6, this is the fourth
As shown in the figure, there is a crystal resonator cut so that the resonance frequency changes linearly with temperature changes.

In a resonator cut to have the characteristics shown in Figure 4, the temperature will be 1°C at 10MHz when the ambient temperature is 0°C.
It changes by 1kHz each time it rises.

Therefore, as the temperature of the food F increases, the resonant frequency of the vibrator 6 increases, but due to the vibration of the vibrator 6, the oscillation circuit section 17 oscillates every time it receives power from the battery 8, and the vibrator After the oscillation signal corresponding to the increase in the resonant frequency of 6 is amplified by the amplification section 18 as food temperature information, it is transmitted by the second antenna 9.

Returning to FIG. 1 again, reference numeral 19 is an operation control circuit provided on the oven 1 side that controls the magnetron Mg, which is the heating source, in conjunction with the catalytic signal sent from the temperature sensing device. Consists of component parts.

That is, among the components, 20 is a reference oscillator that emits a reference pulse, 21 is a pulse shaper that outputs a signal f _P shown in FIG. 5 based on the pulse input from this reference oscillator 20, and 22 is the above-mentioned temperature sensing device. The high-frequency oscillator 23 outputs a signal (signal f _G in FIG. 5) with a frequency close to that of the signal related to temperature information output from the oscillator 23, which is conductive only when the signal f _P is input. An AND gate that passes the signal f _G output from the high frequency oscillator 22 to the next stage, 24 a transmitting amplifier that amplifies the signal obtained through the AND gate 23 and outputs the oscillation induced signal f _A , and 25 this oscillation induced signal. When f _A is transmitted through the first antenna 16, the food temperature information signal f _B transmitted from the temperature sensing device is input through the second antenna 9 and amplified (see signal f _R in FIG. 5). A receiving amplifier 26 is a count time interval signal generator which receives the signal f _P obtained from the pulse shaper 21 and outputs a count time interval signal f _D , and 27 receives a count time interval signal f _D from the generator 26 . An AND gate that passes the signal (food temperature information) f _R input from the receiving amplifier 25 each time it is input and outputs a signal f _C ; 28 indicates the frequency of the food temperature information signal f _C obtained from the AND gate 28; A counter 29 for counting, that is, a display device 30 for displaying the number of counts on the counter 28, that is, the temperature of the food, is used to set a level corresponding to the finished cooking temperature for each type of food F by operating a switch or the like. A cooking temperature setting device that outputs a signal, 31 is the counter 2
The comparator 32 compares the count value of 8 with the level of the signal related to the finished cooking temperature of the food F outputted from the cooking temperature setting device 30, and outputs a heating source drive stop signal f _E when the two match.
This comparator 31 generates a heating source drive stop signal f.
Until _E is input, the power supply voltage is applied to the magnetron Mg to drive it in conjunction with the start of cooking, but when the heating source drive signal f _E is input, the power supply voltage to the magnetron Mg is changed based on this. This is a heating source control power supply circuit that turns off the application.

In this operation control circuit, the oscillation induction signal f _B and the food temperature information signal f _R are applied to the AND gate 27, but as is clear from the waveform diagram in FIG. Since the phase of f _D is delayed from that of the gate signal f _P , only the food temperature information signal f _R is output from the AND gate 27.

Further, if the vibrator 6 has the characteristics shown in FIG. 4, it is convenient to set the pulse width of the count time interval signal f _D output by the count time interval signal generator 26 to 1 ms.

That is, when the resonant frequency of the vibrator 6 is 0°C
10000MHz, 10100MHz at 100℃, so 1ms
When combined with the pulse width, 10000 pulses at 0℃,
At 100℃, there are 10,100 pulses. Therefore, if we take this number of pulses in the last three digits, at 0°C, 0 pulse, 100
When the temperature is 1°C, there are 100 pulses, which means 1 pulse per 1°C, which is convenient for processing by the counter 28.

The present invention is constructed as described above,
The effect will be explained below.

Place the food F on the turntable 2 in the oven 1, pierce the food F with the temperature probe 3 with the reed switch 13 turned on using the switch actuator 15, and in this state close the door of the oven 1 (not shown). At the same time, when a cooking switch (not shown) provided on the front side of the orb is turned on, the heating source control power supply circuit 32 applies power supply voltage to the magnetron Mg to drive it and start the cooking operation.

At this time, when the reed switch 13 is turned on, the oscillation circuit of the temperature-sensitive probe 3 enters a standby state for transmitting the temperature information signal f _B based on the temperature detection of the vibrator 6.

On the other hand, when the switch is turned on, the reference oscillator 2 is activated in the operation control circuit 19 on the oven 1 side.
0 and the high frequency oscillator 22, the oscillation induced signal f _A output from the transmission amplifier 24 is transmitted toward the second antenna 9 through the first antenna 16.

Therefore, in the oscillation circuit of the temperature sensing device, the power of the battery 8 is applied to the oscillation and amplification circuit sections 17 and 18 each time this oscillation induction signal f _A is received, so that the oscillation of the vibrator 6 is performed each time. A food temperature information signal f _B having a frequency (indicating the temperature of the food F) corresponding to the resonance frequency of the vibrator 6 is transmitted to the first antenna through the second antenna 9.
The signal is transmitted toward the antenna 16.

The food temperature information signal f _B received by the first antenna 16 is amplified by the receiving amplifier 25 to become a signal f _R , and then a count time interval signal f _D is output from the count time interval signal generator 26. Each time the signal f _C is inputted to the counter 28 through the AND gate 27, the frequency is counted.

Of course, the count value of the counter 28 is displayed on the display device 29 and is compared with the finished cooking temperature signal level of the food F outputted from the cooking temperature setting device 30 by the comparator 31.

As a result of this comparison, when the temperature of the food F does not reach the predetermined value and the count value at the counter 28 does not reach the finished cooking temperature signal level, the comparator 31 does not output the heating source drive stop signal _fE , and the heating source The control power circuit 32 is a magnetron Mg
Continue to drive.

As the cooking progresses, the temperature of the food F reaches a predetermined value, and the resonant frequency of the vibrator 6 increases accordingly, causing the count value of the counter 28 (food temperature information signal f When the frequency of _C ) matches the level of the finished cooking temperature signal, the comparator 31 gives a heating source operation stop signal f _E to the heating source control power supply circuit 32, which causes the circuit 32 to stop driving the magnetron Mg and start cooking. finish.

The present invention consists of a temperature sensing element that detects the temperature of food and an oscillation means that sends a food temperature information signal to an operation control circuit provided on the oven side in response to a detection signal from the temperature sensing element. In the device in which the heating source is controlled through the operation control circuit, the operation control circuit is provided with means for intermittently applying an oscillation induction signal to the temperature sensing device;
By providing the temperature sensing device with a switch means that receives the oscillation induction signal and supplies battery power to the oscillation means for a predetermined period of time, consumption of the power source battery for driving the oscillation means of the temperature sensing device can be reduced. It is of high practical value for a heating source control device for a cooking device, since it can prevent this as much as possible, and furthermore, it can use a small-capacity power source battery to make the temperature-sensing device more compact.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram of the configuration of a cooking device equipped with the device according to the present invention, Fig. 2 is a sectional view of a temperature-sensitive probe of the device according to the present invention, and Fig. 3 is a diagram showing various parts of the temperature-sensitive probe. An equivalent circuit diagram, FIG. 4 is a characteristic diagram of a resonator (crystal resonator) installed in the same temperature-sensitive probe, and FIG. 5 is a diagram showing output waveforms of various parts of the device according to the present invention. . 1: oven, 3: temperature probe, 6: vibrator, 8: battery, 9: second antenna, 17: oscillation circuit section, 18: amplifier circuit section, 19: operation control circuit,
Mg: Magnetron.

Claims (1)

[Claims] 1. A temperature sensing device consisting of a temperature sensing element that detects the temperature of the food and an oscillation means that sends a food temperature information signal corresponding to the detection signal from the temperature sensing element to the operation control circuit provided on the oven side, through the operation control circuit. In the device for controlling the heating source, the operation control circuit is provided with means for intermittently applying an oscillation induction signal to the temperature sensing device, and the temperature sensing device is connected to a battery power source in response to the oscillation induction signal. 1. A heating source control device for a cooking device, characterized in that a switch means is provided for supplying the oscillation means with the oscillation means for a predetermined period of time.