JPS581733B2 - cooking oven - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for automatically controlling the heating output of food by measuring the temperature of food placed on a rotary table in a cooking oven such as a microwave oven.

Conventionally, to measure the temperature of food, the tip of a temperature measuring stick is inserted into the food, the temperature sensing element attached to the tip of the measuring stick converts the temperature into an electrical resistance value, and the resistance value is connected to a circuit. The temperature was detected by a device and the heat output was controlled based on the detection signal, but in this case, the connection cord of the temperature measuring rod was inserted into a jack terminal on the wall of the heating chamber and connected to the circuit device.

Therefore, this method could not be used when food was placed on L of the turntable for cooking because the connections would become twisted.

There are also cases where an insertable temperature measuring rod is placed on a rotary table, and the circuit connection between the temperature measuring rod and the circuit device is connected by a slip ring, but this is because the contacts of the slip ring are movable contacts. However, they have disadvantages such as short lifespan and generation of electrical noise.

The method of the present invention converts the temperature of the food into an electrical resistance value using a temperature measuring element, and further converts this into a repetition frequency of strong and weak light of a light emitting element, whereby the signal transmission to the control circuit device is carried out without contact by optical-to-electrical conversion. This eliminates the drawbacks of conventional devices.

Embodiments of the method of the present invention will be described below using an example of use in a microwave oven with reference to the drawings.

Figure 1 is a block diagram illustrating an overview of the operation of the present invention.
2 is a heating chamber, 2 is a food, 3 is a saucer on which the food is placed, 4 is a rotary table that rotates with the food and saucer placed on it, 5 is a temperature measuring rod that is inserted into the food to measure the internal temperature, and 6 is a temperature measuring rod. It is an oscillator that oscillates at a frequency determined by the electrical resistance of the temperature sensing element placed at the tip of the rotary table.Actually, it is attached to the rotary table 4 and rotates synergistically with the rotary table, similar to the temperature measurement tube.

7 is a control circuit device, which includes a photoelectric converter 8 that receives the light emission output of the oscillator 6 and converts it into an electric pulse; and a photoelectric converter 8 that receives the voltage pulse of the photoelectric converter and converts it into a frequency, and compares this with the frequency set in Betsu. It has a frequency inverter 9.

A magnetron driver 10 drives the magnetron 11 in response to a command from the control circuit device.

Figure 2 shows the oscillator circuit in Figure 1 and its peripheral circuits, where 5 is a temperature measuring rod, 61 and 62 are inverter circuits, 63 is a capacitor, 64 is a DC power supply, and 6
5 is a switch that is switched from closed to open when a temperature measuring rod is inserted, and 66 is a light emitting element.

Reference numeral 7 denotes a control circuit device, the input side of which is comprised of a light receiving element 71 and an input resistor 72 that receives an input current.

Further, FIG. 3 is a circuit diagram for explaining the oscillation circuit 6.

FIG. 4 shows operating waveforms of each part of this oscillation circuit.

FIG. 5 is a side view of the microwave oven of the present invention, and FIG. 6 is a cross-sectional view taken along a dashed line.

In Figure 6, 1 is a heating chamber, 2 is food, 3 is a saucer, 4
5 is a rotary table, 5 is a state in which the temperature measuring rod is inserted into the storage part 12 of the rotary table, and 5' is a state in which the temperature measuring rod is inserted into the food 2.

Reference numeral 6 denotes an oscillator, which is composed of an inverter, a power source, a capacitor light emitting element, and a switch, and is attached to the radio wave shield box 13, and the light emitting element 66 is arranged in alignment with the hole 14 in the center of the box.

15 is a bottom plate of the heating chamber, and a hole 16 is provided in the center thereof.

Reference numeral 17 denotes a light-receiving element mounting bracket, which has a long hole 18 in its center, and a light-receiving element 71 is disposed at the end of the hole.

The light emitting element 66, the center hole 14 of the radio wave shield box, the elongated hole 18 of the light receiving element mounting bracket 17, and the light receiving element 71 are fixed so that their center lines are aligned with each other, so that the light emitted from the light emitting element is directly projected onto the light receiving element. I try to do that.

19 is a magnet attached to the rotary table 4, and 20 is a magnet attached to the lower rotary plate 21. The figure shows that the rotary table 4 rotates in accordance with the rotation of the lower rotary plate 21 due to the electromagnetic attraction of these magnets. This is an example.

FIG. 7 is an enlarged view of the temperature measuring rod storage section 12 shown in FIG. 6.

In FIG. 7, reference numeral 22 denotes a housing main body, which is fixed to the rotary table 4 and has a hole 24 into which the tip 23 of the temperature measuring rod 5 is inserted.

Further, a switch 65 is attached to the main body 22 of the storage section, and has a fixed piece 25 and a movable piece 26.

When the temperature measuring rod 5 is inserted into the storage part, the movable piece 26 is pushed and moved by the tip of the measuring rod, and the connection with the fixed piece is made at each contact point 27 . 28, and the switch changes from "closed" to "open" state.

Next, the operating mode of the microwave oven of the present invention will be explained.

First, move the temperature side fixed rod 5 to the food 2 as shown in Figure 6.
and set the temperature corresponding value using the control circuit device 7.

Next, the food is heated by the magnetron 11.

After heating, the changing food temperature is measured by the tip 23 of the temperature measuring rod 5.
This is transmitted as a change in the resistance value of a temperature-sensitive resistor 51 (which may be a thermistor) enclosed in the temperature-sensitive resistor 51 (which may be a thermistor).

Since this resistor is included in the oscillator 6 shown in FIGS. 2 and 3, the oscillation frequency of the oscillator changes depending on the resistance value of the resistor 51, that is, the radiant element at the tip of the temperature measuring rod.

As this oscillator, the known circuit shown in the figure can be used.

In the circuit shown in FIG. 3, two stages of inverters 61 and 62 (or NOR gates) are connected in series to form a positive feedback system, and the capacitor 63 is charged and discharged with a time constant determined by the intermediate capacitor 63 and resistor 51. The oscillation waveform shown is obtained.

4. FIG. 1 shows the output waveform of the inverter 62, 2 the input waveform of the inverter 61, and 3 the output waveform of the inverter 61.

Since the light emitting element 66 shown in FIG. 2 is connected to the output end of the inverter 62, a rectangular current flows as an oscillator output, and the light emitting element 66 repeats blinking at the oscillation frequency.

At this time, the switch 65 is in a "closed" state because the temperature measuring tube is removed from the housing 12, and the DC power source 64 is connected through this switch 65 as a power supply for the oscillation circuit.

As shown in FIG. 6, the blinking light of the light emitting element 66 is received through the central hole of the radio wave shield box 13 housing the oscillation circuit 6, the central hole of the bottom plate of the heating chamber, and the elongated hole of the light receiving element mounting bracket. The element 71 is reached.

Here, the shield box 13 shields the inside from radio waves emitted by the magnetron.

This light-receiving element is a phototransistor or a photodiode, and as shown in FIG.

That is, the photoelectric converter 8 shown in FIG. 1 performs photovoltage conversion to obtain the voltage across the resistor 71.

Furthermore, the control circuit device 7 compares the frequency of this voltage with a preset frequency corresponding to the temperature, detects when they match, and uses the detection signal to control the output to stop or adjust the heating output by the magnetron. The output of the magnetron 11 is controlled by applying it to the fugnetron and driver 10.

In addition, when cooking other than when food is heated under control by temperature measurement or when the microwave oven is not in use, the temperature measuring rod is inserted into the storage section 12 of the turntable 4, as shown in FIG. .

As shown in FIG. 27 and the contact 28 of the fixed piece 25 are separated from each other.

Therefore, as shown in FIG. 2, the switch 65 is "open" and the connection of the DC power supply 64 in the oscillation circuit 6 is closed. Since it only takes time to heat the food under control, the battery consumption is much less than when it is always connected.

As explained above, according to the present invention, the following effects can be expected.

(1) Since the connection cord of the temperature measuring rod is connected to the rotary table on which the food is placed rather than to the wall of the heating chamber, the connection cord will not be twisted by the rotation of the rotary table, so the food can be placed on the rotary table. Cooking with less uneven heating can be achieved easily.

(2) The low resistance value of the temperature sensing element of the temperature measuring rod is converted into a frequency by an oscillation circuit, and the temperature measurement data is further transmitted to the control circuit device by photoelectric conversion.

Since this non-contact transmission method is used, there are disadvantages such as the short life of the contact part and the generation of electrical noise, which is the case when the circuit connection between the temperature measuring rod and the circuit device is made using a slip ring. It can be resolved satisfactorily.

(3) By installing a normally closed contact switch in the storage part where the deepness measuring rod is inserted when not in use, the DC power supply for the oscillation circuit is only used when measuring temperature, resulting in less wear and tear and a smaller volume. You can use small dry batteries.

Furthermore, since the entire oscillation circuit is small and lightweight, it is easy to attach it to a rotary table and rotate it along with it.

[Brief explanation of the drawing]

FIG. 1 shows an embodiment of the present invention, in which a temperature measuring rod,
A block diagram explaining the operation outline of a microwave oven having an oscillator and a photoelectric converter, FIG. 2 is a diagram showing the firing circuit and its peripheral circuit in the above embodiment, and FIG. 3 is a diagram for explaining the firing circuit. A circuit diagram, FIG. 4 is a diagram showing operating waveforms of each part of the oscillation circuit, FIG. 5 is a side view of the microwave oven of the present invention,
Figure 6 is a cross-sectional view taken along the dashed line in Figure 5, and Figure 7 is a cross-sectional view taken along the dashed line in Figure 5.
FIG. 3 is an enlarged view of the measuring rod storage section shown in the figure. 1... Heating chamber, 2... Food to be heated, 3
...Saucer, 4...Rotary table, 5...
...Temperature measuring stick, 6...Oscillation circuit, 16...
...Central hole, 66...Light emitting element, 17...
...Mounting bracket hole, 71... Light receiving element, 12
...Storage department, 13...Radio wave rood box,
51...Temperature sensing element at the tip of the temperature measuring rod, 22...
...Storage unit body, 27, 28...Movable piece,
Each contact of the fixed piece, 7... Control circuit device, 10.
...Magnetron driver, 11...Magnetron.

Claims (1)

[Claims] 1. A main body case, a heating chamber formed within the main body case, a rotary table rotatably disposed on the bottom plate of the heating chamber, and a saucer placed on the rotary table. , an insertion type temperature measuring rod that is inserted into the inside of the heated food placed on the saucer to measure the internal temperature of the food, an oscillation circuit that oscillates at an oscillation frequency determined by the temperature value, and an oscillation circuit that oscillates at an oscillation frequency determined by the temperature value. a control circuit device for controlling the heating output to be stopped or reduced in response to the frequency output of the circuit;
The oscillation circuit has a light emitting element that repeats brightness and darkness at a repetition frequency equal to the oscillation frequency, a light receiving element that receives light from the light emitting element is disposed on the bottom plate, and the control device controls the intensity of the light received by the light receiving element. A cooking oven characterized in that the current flowing through this element is changed according to the current, and the frequency of this current is input. 2. In the cooking oven according to claim 1, when cooking is not performed by temperature measurement, a storage section into which a temperature measurement rod is inserted is installed on the rotary table, and this storage section is provided with a storage section for inserting a temperature measurement rod. A cooking oven characterized by having a normally closed contact switch that opens when inserted. 3. The normally closed contact switch according to claim 2 forms a part of the oscillation circuit, and opens and closes the power supply to the oscillation circuit, and the power supply is mounted on the rotary table, A cooking oven characterized by synergistic rotation similar to the switch.