JPS6012753B2 - Heating source control device for cooking equipment - 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, in such devices, the temperature of the food is detected by a heat-sensitive element attached to a temperature-sensitive probe inserted into the food, and based on this detected temperature, a heating source (magnetron ) controls the drive.

Among these devices, there is a wired type device in which the stripe sensing probe is connected to the operation control circuit via a cable, such as the device shown in U.S. Pat. Patent application No. 52-5546 “Temperature control device” filed on January 20, 1952
The ultrasonic oscillator is excited by the food temperature information signal detected by the heat-sensitive element to oscillate ultrasonic waves, and the ultrasonic waves are received by a receiver installed on the oven side and sent to the operation control circuit. There is a so-called wireless type that guides the heating source and controls the heating source.

However, the former method requires consideration of the thermal effect on the cable, and cannot be applied to modern microwave ovens that heat food while rotating it on a turntable. In order to solve the former problem, it is necessary to incorporate a battery into the temperature-sensitive probe, which increases the size and cost of the temperature-sensitive probe. The present invention was invented in view of the drawbacks of the conventional devices, and focuses on the fact that the resonant frequency of a crystal resonator or a ceramic resonator changes with temperature changes, and converts such a resonator into a heat-sensitive element. When used as a thermosensor, a resonant circuit is formed with this vibrator, a capacitor, a transmitting/receiving antenna, etc. inside the temperature probe, and a high frequency oscillation induction signal is applied to this resonant circuit from the operation control circuit on the oven side. The resonant circuit is activated to oscillate a high-frequency temperature information signal, and the oscillation output is observed by an operation control circuit to control the heating source.

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 the figure, 1 is open, and a magnetron Mg as a heating source is provided on the ceiling surface, and a turntable 2 is provided 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 which has an insertion part 4 made of a metal tube with a pongee diameter with one end pointed as shown in FIG. It is composed of a handle tube section 5 made of a metal tube having an antenna attachment section 5b at the other end and a board attachment section 5c provided halfway inside.

This temperature-sensitive probe 3 supports a vibrator (crystal vibrator or ceramic vibrator) 6 in the tip of its insertion part 4, and also supports a substrate 7 in the base 2 plate attachment part 5c in the handle tube part 5. At the same time, a probe antenna 8 is attached to the antenna attachment part 5b, and a choke structure 5d is formed in the handle tube part 5 to attenuate the microwaves that enter through the antenna attachment part 5b. 9 connects the circuit of the vibrating triplet 6 and the substrate 7, and a lead wire 10 connects this circuit to the probe antenna 8, respectively.

Furthermore, a protective film 311 is formed on the outer surface of the handle tube portion 5, including the probe antenna 8, by molding rubber or resin.

While the configuration of the temperature sensing probe 3 is as described above, the vibrator 6 is shared with the probe antenna 8 and the variable capacitor 12 provided in the circuit of the substrate 7 as shown in the equivalent circuit of FIG. It forms a four-wave circuit.

Therefore, when the overflow probe 3 is inserted into the food F and the vibrator 6 is detecting the temperature of the food F, an oscillation induced signal f^ (see Fig. 6) is sent from the operation control circuit, which will be described later, through the blow antenna 8. is applied, the resonant circuit causes an oscillation operation, and when the resonant frequency of the vibrator 6 matches the frequency of the oscillation-induced signal, the resonant circuit causes a damped oscillation (signal fB in FIG. 6). This damped vibration is conversely transmitted toward the oven 1 side via the probe antenna 8 and applied to the operation control circuit.

This damped vibration does not occur under any conditions, but occurs when the resonance frequency of the vibrator 6 and the frequency of the oscillation signal f^ substantially match. Of course, it depends on the Q of the vibrator 6. Q
If Q is low, it will occur even if the two frequencies are far apart, but if Q is high, it will not occur unless they almost match. The above-mentioned vibrator 6 may be a crystal vibrator cut so that the resonance frequency varies linearly with temperature changes, as shown in FIG.

In a resonator cut to have the characteristics shown in Figure 4, when the ambient temperature is 0°C, the I
KHz changes. Returning again to FIG. 1, 13 is the above-mentioned operation control circuit, which is located on the oven 1 side and connected to the oven 1.
Signals are sent to and received from the resonant circuit through an oven antenna 14 provided on the ceiling of the oven.

Of the components (constituting this operation control circuit 13), a reference pulse generator designated by reference numeral 15 generates first to third gate pulses A, B as shown in the waveform diagram of FIG.
, C and repetitive pulses D, respectively.

Note that this repetitive pulse D is 1 for the reason described in detail later.
It is a signal that repeats the voltage increase of the aircraft in each period with one second as one period, and if we look only at the period of one second (one cycle), it is divided into 100 steps every 10 seconds, and the steps start from the first step. The voltage is increased in waves by a certain amount.

The first gate pulse A is a signal output corresponding to the first half of each step of the repetitive pulse D, and therefore has a pulse width of 5 s.

Of course, the output may be made corresponding to the latter half of each step. The second gate pulse B is a signal that is output corresponding to the latter half of each step of the repetitive pulse D. In other words, it is a signal that is output when the first gate pulse A is at the L level, and its pulse width is approximately 1. It is s.

Further, the third gate pulse C is a pulse that is output with a slightly delayed phase from the second gate pulse B, and its pulse width is lws.

Further, what is designated next by reference numeral 16 is a variable frequency oscillator, in which a variable capacitor is usually used, and by changing the reverse voltage applied to the variable capacitor, the capacitance is changed and the oscillation frequency is changed.

Therefore, if the above-mentioned repetitive pulse D is applied to the variable frequency oscillator 16 and the voltage is gradually increased like this pulse, the capacitance of the varicap will gradually decrease, while the frequency will be repeated Z and the voltage of the pulse D will change. gradually increases depending on the still,
This change in frequency is caused by the characteristics of the vibrator 6 shown in FIG.
If o is acceptable, the frequency changes stepwise from 10.00 µM ratio to 10.10 MHz at a rate of 1°C IK ratio according to this condition, and this change is repeated to correspond to the change in pulse D. Repeat every second (one cycle). As will be described later, one period of the repetitive pulse D is divided into 100 steps for each lows as described above because attention is paid to the above conditions. Of course, if such conditions change, it is necessary to increase or decrease the number of steps in one cycle in accordance with the conditions, and it is also necessary to change the frequency difference between each step. 17 is a band gate, and every time the first gate pulse A is input, the temperature signal (E in FIG. 5) given from the variable frequency oscillator 16 is intermittently extracted and oscillated in the latter half of each step unit. This is output as an induced signal f^, which is amplified by the next-stage transmission amplifier 18 and then transmitted from the oven antenna 14 into the oven 1.

Reference numeral 19 transmits the temperature information signal fB transmitted by the resonant circuit through the probe antenna 8 to the oven antenna 14.
(See the signal in FIG. 5F) and amplifies it to generate signal G.

20 is an AND gate which, when the third gate pulse C and the damped oscillation component 〇 of the temperature information signal G are input, outputs this damped oscillation component to the next stage as food temperature information (signal J in FIG. 5). It is.

In this case, since the pulse width of the third gate pulse C is 1 second, the temperature information signal outputted from the AND gate 20 is 000, 10000 pulses, and 10 pi○.
The signal is 10,100 pulses. 21 is an AND gate that outputs the signal date shown in FIG. 5 when the second gate pulse B and the damped vibration component are input, and 22 is a reset pulse (signal 1 in FIG. 5) that integrates this signal date. This is an integrator that outputs as .

23 counts the frequency of the temperature information signal J input from the AND gate 201, and resets this count value by the reset pulse 1 obtained from the integrator 22 immediately before the next new temperature information signal J is input. This is a counter that is held until the

Reference numeral 24 indicates a display device that displays the count value of the counter 23 as the temperature of the food, and reference numeral 25 indicates an operation droplet provided on the operation panel at the front of the oven (not shown), which displays a cooking finish temperature signal at a level corresponding to the type and amount of food, etc. The cooking temperature setting device 26, which is output by operating the counter 23, compares the count value (food temperature) of the counter 23 with the finished cooking temperature output by the cooking temperature setting device 25, and when the two match, that is, This is a comparator that outputs a heating source drive stop signal when food F reaches the finished cooking temperature.

Reference numeral 27 indicates the magnetron M from the cooking start caused by the operation of the cooking switch (not shown) provided on the operation panel.
This is a heating source control power supply circuit that applies a power supply voltage to Mg to drive it, and when the heating source drive stop signal is input, stops outputting the power supply voltage and stops driving the magnetron Mg.

The present invention is constructed in a superior manner, and its operation will be explained below. As shown in FIG. 1, the food F is placed on the turntable 2, and the insertion tube 4 of the temperature-sensitive probe 3 is inserted into the food F, and in this state, the oven door (not shown) is closed. At the same time, when the cooking switch is turned on, the magnetron M is driven by the operation of the heating source control power supply circuit 27, and in response, dielectric heating of the food F starts.

Further, when the cooking switch is turned on, the reference pulse generator 15 is activated to generate 0 pulses A, 0 pulses A, and 0 pulses A and 0 for the first to third gates, respectively.
Output B, C and repeated pulses ○.

This repetitive pulse 0 is applied to a variable frequency oscillator 16 which changes the frequency from 10.000 MHz to 10.1 MHz in steps at a rate of 1001K ratio (l0ws).
A temperature signal E with a 00M ratio is output at a rate of one cycle per second. The signal E output from the variable frequency oscillator 16 is ANDed by the first gate pulse A at the AND gate 17, and as shown in FIG. The signal becomes an electromotive signal f^ and is amplified by the transmitting amplifier 18 and then radiated into the oven through the open antenna 14.

Then, in the oven, the probe antenna 8 of the overflow probe 3 receives the oscillation induced signal f^ and guides it to the resonant circuit, so that the resonant circuit detects the food based on the input of this oscillation induced signal f^. It resonates with the resonant frequency of the vibrator 6 detecting the temperature of F, and conversely transmits a signal fB accompanying this resonance to the oven antenna 14 through the probe antenna 8.

``In such a case, each time the resonant frequency of the vibrator 6 and the frequency of the oscillation induced signal f^ due to the temperature of the food F match, the resonant circuit causes damped vibration as shown in FIG. The resulting damped vibration is given to the operation control circuit 13 through the oven antenna 14 and prompts the counter 23 to operate.That is, if the temperature of the food F has now risen to 20qC due to the electrical heating, the When the oscillation induced signal f^ (20th step of a certain cycle) with a frequency (10.020 MHz) is input to the resonant circuit through the probe antenna 8, this causes the temperature of the food F to be 2000 MHz.
Since it matches the resonant frequency of the vibrator 6 based on The component (see F' of signal F in FIG. 5) is input to the receiving amplifier 19 through the probe antenna 8 and the oven antenna 14.

The signal fB containing the damped vibration component inputted to the receiving amplifier 19 is amplified by the receiving amplifier 19 to become the signal G shown in FIG. 5, and then inputted to the AND gates 20 and 21, respectively.

At this time, the AND gate 21 inputs the third signal to the AND gate 20.
Prior to the input of the gate pulse C, the second gate pulse B is input at the same time as the damped oscillation component 〇, so the signal date is outputted in conjunction with this, and such a signal is integrated by the integrator 22 as the reset pulse 1. The data is input to the counter 23 and the counter 23 is reset.

Therefore, the counter 23 erases the previous count value (frequency corresponding to 19:00) that had been held until then. On the other hand, in the AND gate 20, the third gate pulse C is input to the damped vibration component at the same time as '', a little later than the timing at which the second gate pulse B is input to the AND gate 21. Outputs a temperature information signal J, and sends this signal J to the counter 23 which was reset earlier.
and count the frequency (10020 days 2).

The count value of this counter 23 is displayed as the food temperature on the display device 24, and is compared with the finished cooking temperature (100:00 in this example) output from the cooking temperature setting device 25 on the comparator 26. Ru. As a result of this comparison, the two do not match, so "This comparator 26
The heating source drive stop signal is not output from the heating source control power supply circuit 27, so the heating source control power supply circuit 27 continues to drive the magnetron Mg. In this way, the resonant frequency of the vibrator and the output signal of the variable frequency oscillator 16 (temperature signal E: oscillation induced signal f^)
, that is, each time the food temperature matches the level of the temperature signal E, the resonant circuit causes a damped vibration, and each time the counter 23 performs a counting operation, the food temperature at that time is displayed on the display device 24.

Of course, the food temperature and the level of the temperature signal E always match at some step of each period of the temperature signal E, and it goes without saying that the same operation is performed each time. As a result, the repetition of such operations and the dielectric heating by the magnetron progress, and the temperature of the food F reaches the predetermined temperature of 100 qo.
Then, the 100th step (frequency corresponding to 100qo) of a certain period of the oscillation signal f^ based on the temperature signal E output from the variable frequency oscillator 16 is
4 and 8 to the resonant circuit in the temperature-sensitive blob, the resonant circuit causes damped oscillation as described above, and the signal fB containing this damped oscillation component conversely causes the antennas 8 and 14 to vibrate. The signal is applied to the receiving amplifier 19 via the receiving amplifier 19.

In this way, the signal fB including the damped vibration component is transmitted to the receiving amplifier 1.
9, the temperature information signal G is output from the amplifier 19, and the AND gate 21'
While the counter 23 is reset by the action of the integrator 22, the frequency of the temperature information signal J output from the AND gate 20 (frequency corresponding to a certain period of 10000 = 10
q-th electric step) is counted by the counter 23 set to IJ.

This count value is immediately displayed as the food temperature on the display device 24 and is compared with the finished cooking temperature in the comparator 26.

The comparator 26 outputs a heating source drive stop signal in response to the count value, that is, when the food temperature matches the finished cooking temperature, and the heating source control Z control power supply circuit 27 outputs a heating source drive stop signal. Stop driving and finish heating.

As described above, the present invention controls a heating source through an operation control circuit provided on the oven side based on information obtained from a heat-sensitive device provided independently in the oven.
The above-mentioned heat-sensing device is formed of a resonant circuit formed by a heat-sensing element, a blow antenna, a capacitor, etc. that changes the resonance frequency according to changes in food temperature, and a temperature-sensing probe that accommodates these and is inserted into the food. The control circuit includes a temperature signal generating means for outputting a temperature signal whose frequency changes stepwise in accordance with the temperature to the machine every two cycles, and a temperature signal generating means for intermittently extracting the temperature signal for each step and using it as an oscillation signal. , an oscillation-induced signal generating means that sends the oscillation-induced signal to the probe antenna 2 through an oven antenna provided in the oven, and a damped vibration of the resonant circuit caused by the matching of the oscillation-induced signal and the resonant frequency of the heat-sensitive element through both ovens. A counter that counts the frequency when input, and means for resetting the counter before the counter starts counting by inputting the damped vibration, and the heating source is activated based on the count value of the counter. Since the present invention provides a heating source control device for a cooking device to be controlled, it can be well applied to devices that heat food while rotating it on a turntable, and it is also small because there is no need to house a battery in the sensitive probe. It can be an inexpensive device.

Moreover, since the counter is made to count new information while resetting the count value one by one, it is an excellent invention that enables accurate recognition of food temperature.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram of the configuration of a microwave oven equipped with a 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 in such a temperature-sensitive probe. Fig. 4 is a characteristic diagram of the vibrator included in the above temperature sensing probe, Fig. 5 is an output waveform diagram at each location in Fig. 1, and Fig. 6 is the above temperature sensing probe. Equivalent circuit in blob (
FIG. 3 is a waveform diagram illustrating an oscillation induced signal input to a resonant circuit (resonant circuit) and vibrations of the resonant circuit. 1: oven, 3: temperature probe, 6: vibrator, 8: probe antenna, 12: variable capacitor, 13: operation control circuit, 14: oven antenna, 16: variable frequency oscillator, 23: counter. Figure 2 Figure 3 Figure 1 Figure 4 Figure 5 Figure 6

Claims (1)

[Claims] 1. In a device that controls the heating source through an operation control circuit installed on the oven side based on information obtained from a heat-sensitive device installed independently in the oven, the heat-sensitive device changes its resonant frequency depending on changes in food temperature. It is formed by a resonant circuit formed by a heat-sensitive element, a probe antenna, and a capacitor, and a temperature-sensitive probe that houses these and is inserted into the food. Temperature signal generating means for changing the frequency in steps; and oscillation inducing signal generating means for intermittently extracting the temperature signal at each step to generate an oscillation inducing signal and sending it to the probe antenna through an oven antenna provided in the oven. a counter that counts the frequency of the damped vibration of the resonant circuit caused by the matching of the oscillation induced signal and the resonant frequency of the heat-sensitive element when it is inputted through both the antennas; 1. A heating source control device for a cooking device, comprising means for resetting the counter before starting cooking, and controlling the heating source based on the count value of the counter.