JPH05340546A - Cooking device - Google Patents

Abstract

PURPOSE:To properly judge whether a light receiving element receives a light from a light emitting element or not even when it receives a room light of the device or the temperature of the light receiving element rises. CONSTITUTION:The device wherein a material to be cooked in a kitchen is heated by a magnetron 2, and the height of the material or existence of belongings thereto, etc., are detected by a light sensor is also provided with a control circuit 18, which judges a phototransistor receives a light from a light emitting diode of the light sensor when the difference of the light receiving levels of the phototransistor between not in emission of the diode and in emission of that exceeds the set value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heating cooker provided with an optical sensor for detecting the height of food in the cooking chamber and the presence or absence of accessories in the cooking chamber.

[0002]

2. Description of the Related Art A heating cooker, for example, a microwave oven is provided with an optical sensor for detecting the height of food and the presence or absence of accessories, and cooking is automatically performed based on the height detected by the optical sensor. Some are configured to do. The optical sensor is composed of a light projecting element and a light receiving element which are arranged on a side surface of the cooking chamber. Then, for example, in the case of a transmissive optical sensor, the object to be detected is detected based on whether or not the light projected from the light projecting element is shielded by the object to be detected such as food or accessories. .. Specifically, when the light receiving level of the light receiving element during the light projection of the light projecting element exceeds a predetermined threshold value, the light projected from the light projecting element is received by the light receiving element without being blocked. Judgment is made and it is detected that there is no object to be detected.

[0003]

However, in the above-mentioned conventional structure, when the interior light arranged in the heating and cooking chamber is turned on, the light receiving level of the light receiving element receives a light from the interior light and the light receiving level of the light receiving element is threshold. The value may exceed the value. In such a case, it may be determined that the light receiving element has received light, and erroneous detection may be made that there is no detected object despite the detected object. Further, when the temperature of the light receiving element rises by performing the cooking, the light receiving level of the light receiving element may exceed the threshold value due to the increase of the dark current of the light receiving element.
Even in such a case, there is a case in which it is erroneously detected that there is no detected object even though the detected object is present.

Therefore, an object of the present invention is to accurately determine whether or not the light is received by the light receiving element even when the light from the interior lamp is received or the temperature of the light receiving element rises. , A heating cooker capable of preventing erroneous detection by an optical sensor is provided.

[0005]

The cooking device of the present invention comprises:
A heating cooker comprising heating means for heating food in a cooking chamber, and an optical sensor having a light projecting element and a light receiving element for detecting the height of the food and the presence or absence of an accessory in the cooking chamber, etc. When the difference between the light receiving level of the light receiving element when the light projecting element of the light sensor is not projecting light and the light receiving level of the light receiving element when the light projecting element projects light exceeds a set value, The light receiving element is characterized in that the light receiving element is provided to determine that the light from the light emitting element is received by the light receiving element.

[0006]

According to the above means, when the difference between the light receiving level of the light receiving element when the light projecting element is not projecting light and the light receiving level of the light receiving element when the light projecting element is projecting exceeds the set value,
Since it is configured to judge that the light receiving element has received the light from the light emitting element, the light from the interior lamp may be received, or the temperature of the light receiving element may rise, so that the light emitting element does not emit light. Even if the light receiving level of the light receiving element is high to some extent,
The adverse effect can be eliminated, and it can be accurately determined whether or not the light from the light projecting element is received by the light receiving element. Therefore, erroneous detection of the optical sensor can be prevented.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a microwave oven will be described below with reference to the drawings. First, in FIG. 2 showing a schematic configuration of the entire microwave oven, a cooking chamber 1 is provided in the microwave oven main body. The front opening of the cooking chamber 1 is opened and closed by a door (not shown).

A machine room is provided on the right side of the cooking chamber 1 and a heating means such as a magnetron 2 and a cooling fan device 3 are arranged in the machine room. The magnetron 2 supplies microwaves into the cooking chamber 1 through the waveguide 4 to heat the food contained in the cooking chamber 1 with high frequency. The cooling fan device 3 includes a fan 5 and a fan motor 6 that rotationally drives the fan 5. When the cooling fan device 3 is operated, the magnetron 2 is cooled by the outside air, and the air that has cooled the magnetron 2 is blown into the cooking chamber 1.

A rotary shaft 8 of a turntable motor 7 is provided on the inner bottom of the cooking chamber 1 so as to project upward, and a turntable 9 is detachably mounted on the rotary shaft 8. ing. The turntable 9 is rotatably driven by the turntable motor 7 via a rotary shaft 8. Food is placed on the turntable 9.

Further, an exhaust port 10 consisting of a large number of small holes is provided in the upper part of the left side wall of the heating and cooking chamber 1. An exhaust duct 11 communicating with the outside of the range main body is provided outside the exhaust port 10. In this case, when the cooling fan device 3 is operated, the air that has cooled the magnetron 2 is blown into the cooking chamber 1, and the air in the cooking chamber 1 passes through the exhaust port 10 and the exhaust duct 11. It is configured to be discharged to the outside. On the other hand, cooking room 1
The interior lamp housing portion 12 is provided in the ceiling portion of the inside compartment, and the interior lamp housing 13 is provided in the interior lamp housing portion 12.

Now, on the left and right side walls of the heating and cooking chamber 1, there are optical sensors 1 for detecting the height of food or a container for containing food.
4 are provided. Specifically, the optical sensor 14 is configured by arranging a plurality of pairs of transmissive optical sensors 15 at predetermined intervals in the vertical direction. Note that FIG. 2 shows a pair of transmissive optical sensors 15. The transmission type optical sensor 15 is, for example, a light emitting diode 16 which is a light emitting element provided on the left side wall of the cooking chamber 1 and a phototransistor which is a light receiving element provided on the right side wall of the heating cooking chamber 1. It consists of 17.

In this case, the phototransistor 17 of the transmissive optical sensor 15 located at a position lower than the food cannot receive light from the light emitting diode 16, whereas the phototransistor 17 located at a position higher than the food. The phototransistor 17 can receive light from the light emitting diode 16. Therefore, the height of the food can be detected according to the light receiving state of each phototransistor 17 of the plurality of transmissive photosensors 15.

Further, in FIG. 1 showing an electrical configuration, a control circuit 18 including a microcomputer is a CPU.
19, ROM 20 and RAM 21 are included, and the ROM 20 stores a control program for controlling the operation of the entire microwave oven. This control circuit 18
Has a function of a light reception determining unit. The control circuit 1
Reference numeral 8 is configured to include various switch signals from the input section 22 having various switches provided on the operation panel, and the above-described photosensor 14, that is, the plurality of light emitting diodes 16 and the phototransistor 17. The photosensor circuit 23 receives a light reception signal of each phototransistor 17.

The control circuit 18 drives and controls the display section 24 provided on the operation panel, drives and controls the magnetron 2 through the drive circuit 25, and drives and controls the fan motor 6 through the drive circuit 26. Then, the turntable motor 7 is drive-controlled via the drive circuit 27, and the interior lamp 1
3 is controlled via a drive circuit 28, and a light emission control signal is given to the optical sensor circuit 23 to control light emission of the plurality of light emitting diodes 16.

Now, FIG. 3 shows a part of the optical sensor circuit 23, that is, an electric circuit (light emitting circuit and light receiving circuit) around one light emitting diode 16 and one phototransistor 17, respectively. In the light projecting circuit of FIG. 3, one end of the light emitting diode 16 is a DC power supply terminal 29 (for example, 20V).
The other end is connected to the ground via the resistor 30 and the NPN transistor 31. The transistor 31 receives a drive pulse as a light emission control signal from the control circuit 18 to the base via the input terminal 32, and is on / off controlled, thereby turning on / off the light emitting diode 16.

On the other hand, in the light receiving circuit, the collector of the phototransistor 17 has a DC power supply terminal 33 (for example, 5).
V) and the emitter is connected to ground via a resistor 34. The intermediate connection point between the emitter of the phototransistor 17 and the resistor 34 is connected to the control circuit 18 as the output terminal 35.

Next, the operation of the above configuration will be described with reference to FIG. 4A and 4D show the light emitting diode 16
The drive pulse Sp applied to the base of the transistor 31 that turns on and off is shown. The pulse width of the drive pulse Sp is set to about 150 μs in this embodiment. The light emitting diode 16 is turned on and emits light only during the pulse width of the drive pulse Sp, that is, during the high level.

When light from the interior lamp 13 is received or the temperature of the phototransistor 17 rises and the dark current increases, as shown in FIGS. 4B and 4E, the light emitting diode 16 is emitted. Even when the light is not projected, that is, when the light emitting diode 16 does not emit light, the phototransistor 17
Is turned on, and the output level of the light receiving signal output from the phototransistor 17, that is, the light receiving level becomes high to some extent.

Here, FIG. 4B shows the light emitting diode 16
4E shows a case in which there is a detected object between the light emitting diode 16 and the phototransistor 17, that is, a case where the light from the light emitting diode 16 is blocked by the detected object. This shows a case where there is no detected object, that is, a case where the light from the light emitting diode 16 is not blocked by the detected object.

By the way, in FIGS. 4B and 4E, the predetermined light receiving level Vth indicates the threshold value explained in the conventional configuration. That is, in the case of the conventional configuration, FIG.
As shown in (b), the light-receiving level exceeds the threshold value Vth even though the light from the light-emitting diode 16 is blocked by the light-emitting diode 16. Therefore, it is determined that the light from is received by the phototransistor 17, and it is erroneously detected that there is no detected object despite the detected object.

On the other hand, in this embodiment, the difference between the light receiving level of the phototransistor 17 when the light emitting diode 16 is not projecting light and the light receiving level of the phototransistor 17 when the light emitting diode 16 is projecting light is a set value. When it exceeds, it is determined that the phototransistor 17 has received the light from the light emitting diode 16.

Specifically, when the light emitting diode 16 is not projecting light, in this case, the light receiving level of the phototransistor 17 at time t1 shown in FIGS. 4B and 4E is detected and the RAM 21 of the control circuit 18 is detected. Remember. When the light emitting diode 16 emits light, in this case, the phototransistor 17 at time t2 shown in FIGS. 4B and 4E.
And the difference between the above-mentioned stored light-reception level is calculated and obtained. Graphs of the calculated differences in the received light levels are shown in FIGS. 4 (c) and 4 (f). Here, FIG. 4C shows a case where the detected object is between the light emitting diode 16 and the phototransistor 17, and FIG.
(F) is a light emitting diode 16 and a phototransistor 17.
The case where there is no object to be detected is shown between and.

As is apparent from FIGS. 4 (c) and 4 (f), the difference between the above light receiving levels is the set value Vth (in this case,
If the value exceeds the threshold value Vth mentioned above), it is determined that the phototransistor 17 has received the light from the light emitting diode 16. On the other hand, if the difference between the light receiving levels does not exceed the set value Vth, the light emitting diode 16
It is determined that the phototransistor 17 does not receive the light from.

When the interior lamp 13 is turned off, or when the temperature of the phototransistor 17 has not risen and the dark current thereof is small, the difference in the light receiving level becomes even larger. Similar to the case described above, it can be accurately determined whether or not the light from the light emitting diode 16 is received by the phototransistor 17.

According to this embodiment having such a configuration, the difference between the light receiving level of the phototransistor 17 when the light emitting diode 16 is not projecting light and the light receiving level of the phototransistor 17 when the light emitting diode 16 is projecting light is generated. Since it is determined that the phototransistor 17 has received the light from the light emitting diode 16 when the set value Vth is exceeded, unlike the conventional configuration, does the phototransistor 17 receive the light from the light emitting diode 16? It is possible to accurately determine whether or not. Therefore, erroneous detection of the optical sensor 14 can be reliably prevented.

In the above embodiment, the optical sensor 14 for detecting the height of food is used, but the present invention is not limited to this. For example, the optical sensor for detecting the number of food may be applied. It may be applied to an optical sensor that detects the presence or absence of an accessory (for example, an inner shelf) that is detachably accommodated in the heating / cooking room 1. Further, although the present invention is applied to the transmissive optical sensor 15, it may be applied to a reflective optical sensor instead. Further, in the above embodiment, the invention is applied to a microwave oven, but it may be applied to a heating cooker that heats food with a heater.

[0027]

As is apparent from the above description, the present invention has the light receiving level of the light receiving element when the light emitting element of the optical sensor is not emitting light and the light receiving level of the light receiving element when the light emitting element is emitting light. When the difference between the light receiving element and the light receiving element is configured to determine that the light receiving element has received the light from the light projecting element when the difference between the light receiving element and the light receiving element is received, Even when the temperature rises, it is possible to accurately determine whether the light is received by the light receiving element, and it is possible to prevent an erroneous detection by the optical sensor, which is an excellent effect.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a schematic vertical sectional front view of a microwave oven.

FIG. 3 is an electric circuit diagram showing a part of an optical sensor circuit.

4A to 4F are time charts of a drive pulse, a light receiving level, and a difference between a light receiving level with and without a detected object.

[Explanation of symbols]

1 is a cooking chamber, 2 is a magnetron (heating means), 13
Is an interior light, 14 is an optical sensor, 16 is a light emitting diode (light emitting element), 17 is a phototransistor (light receiving element), 1
Reference numeral 8 is a control circuit (light receiving determination means), and 23 is an optical sensor circuit.

Claims (1)

[Claims] 1. A heating means for heating food in the cooking chamber, and an optical sensor having a light projecting element and a light receiving element for detecting the height of the food and the presence or absence of accessories in the cooking chamber. In the heating cooker, the difference between the light receiving level of the light receiving element when the light projecting element of the optical sensor is not projecting light and the light receiving level of the light receiving element when the light projecting element projects light exceeds a set value. When
A heating cooker comprising a light receiving determination unit that determines that the light receiving element has received the light from the light projecting element.