JPH0413604B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to an electronically controlled cooking device such as a microwave oven.

(b) Conventional technology In conventional microwave ovens,
As seen in Japanese Patent Application No. 24616, a plurality of door switches are provided which operate in conjunction with doors that open and close the front opening of the heating chamber, and these door switches are integrally attached to a common board. As a result, deviations in the operation timings of the respective door switches based on the opening and closing of the door are suppressed as much as possible.

Therefore, in order to further suppress this deviation, it is preferable to house a plurality of door switches in one switch case.

However, in this case each door switch would be in close proximity, one of the door switches being connected to a circuit for supplying power to the microwave supply circuit, and another door switch controlling the operation of the microwave supply circuit. In devices connected to an electronic control circuit consisting of a microcomputer, etc., the inductive noise generated during the operation of the former door switch is easily transmitted to the electronic control circuit via the latter door switch. This will cause a malfunction. Also, the ratings of the former door switch and the latter door switch are, for example, 15 amperes and 0.1 amperes, respectively;
Therefore, the switch case must be made of an expensive material that can withstand 15 amperes; in this case, for the door switch side, which has a rating of 0.1 ampere, the switch case is unnecessarily expensive and can withstand the rated current. This results in an increase in the cost of the microwave oven.

(c) Problems to be Solved by the Invention An object of the present invention is to integrate a door switch related to an electronic control circuit and other door switches into a single switch case so that there is as little lag in operation timing as possible based on the opening and closing of the door. If the latter door switch is to be housed in a large area, select an appropriate door switch with a large rated capacity, so that when the latter door switch is operated, most of the induced noise that will be transmitted through the former door switch and cause the electronic control circuit to malfunction will occur. The first object is to enable the switch case to be made of inexpensive materials.

(d) Means for Solving the Problems In order to solve the above problems, the present invention provides a heating chamber for storing food, a door for opening and closing the opening of the heating chamber,
A heating energy supply means for supplying heating energy into the heating chamber, an electronic control circuit consisting of a microcomputer, etc. for controlling the drive of this supply means, a commercial power input section, a power cutoff means, and the above input together with the cutoff means. a first door switch interposed between the part and the supply means and interlocked with the opening and closing of the door; and a second door switch interlocked with the opening and closing of the door and actuating the power cutoff means when the first door switch means malfunctions. and a third door switch means that is interlocked with the opening and closing of the door and detected by the electronic control circuit, and the second and third door switch means are housed in one switch case.

(E) Effect With the above means, even if other door switches housed in one switch case together with a door switch related to an electronic control circuit have a large rated capacity, when the door switch is operated, the electronic control circuit is transmitted through the former door switch. Almost no induced noise that may cause malfunction is generated, and the switch case can be made inexpensive.

(F) Embodiment A microwave oven according to an embodiment of the present invention will be described below based on the drawings.

FIG. 1 shows the external appearance of a microwave oven, in which a heating chamber 2 is disposed within a main body 1, and a door 4 for opening and closing a front opening 3 of this heating chamber is provided. Also, main body 1
A keyboard 5 for inputting information regarding heating is arranged on the front right side of the screen.

FIG. 2 shows details of the latch mechanism of the door 4. Elongated holes 7a and 7b are formed in the front plate 6 around the front opening 3.
is formed, and door latches 8a and 8b rotatably disposed on the door 4 are inserted into this elongated hole when the door 4 is closed. On the other hand, a common board 9 is fixed to the back surface of the front plate 6, and door stops 10a, 10b are engaged with door latches 8a, 8b inserted through the elongated holes 7a, 7b when the door 4 is closed. are integrally provided.
The door latch 8a for this door stopper,
The operational relationship of 8b is shown in detail in Japanese Utility Model Application Publication No. 58-24616, and its explanation will be omitted.

Furthermore, first to fourth door switches 11a to 11d are integrally attached to the board 9. The first and fourth door switches 11a and 11d are
The rotary lever 1 is moved by the door latch 8a, 8b which engages with the door stopper 10a, 10b when the door 4 is closed.
It is turned on via 2a and 12b. The second and third door switches 11b, 11c are housed integrally in one switch case 13, as shown in detail in FIG.
Each door latch 8b engages with a door stopper 10b when the door 4 is closed, and is actuated via a rotary lever 14. That is, when the door latch 8b engages with the door stopper 10b, the rotating lever 14 rotates counterclockwise, and the plunger 15 housed in the switch case 13 moves upward against the force of the spring 16. This turns off the second door switch 11b and turns on the third door switch 11c.

FIG. 4 shows the circuit of the microwave oven. There is a microwave supply circuit 17 in the heating chamber 2 for supplying microwaves as heating energy, and this circuit includes a magnetron 18 and a half-wave voltage doubler rectifier circuit 19.
and a high voltage transformer 20. and,
The supply circuit 17 is connected to a commercial power input section 23 via the first and fourth door switches 11a, 11d, a power cutoff fuse 21, and a triac 22. In addition, the second door switch 11b
is connected to the first door switch 11a, the fuse 21, and the input section 23 to form a closed circuit. In this case, the first and second door switches 11
a, 11b is such that the operation timing is such that when the door is closed, the second door switch 11b is turned off and then the first door switch 11a is turned on, and when the door is opened, the first door switch 11a is turned off and then the second door switch 11a is turned on.
It is attached so that the door switch 11b is turned on.

If the first door switch 11a has a contact welding failure for some reason, the first door switch 11a will be turned on when the door is opened, while the second door switch 11b will of course be turned on as described above. Fuse 21 is blown,
As a result, power cannot be supplied to the supply circuit 17 from now on unless the above-mentioned failure is corrected, thus maintaining the safety of the microwave oven.

Furthermore, an electronic control circuit 24 consisting of a microcomputer or the like is provided to control the microwave oven. This circuit is designed to control ON/OFF of the triac 22 based on information from the keyboard 5. Further, the electronic control circuit 24 is connected to the third door switch 11c, and for safety, when the door 4 is closed, the third door switch 11c is connected to the third door switch 11c.
The on/off control of the triax 22 is not performed unless the door switch 11c is turned on.

Here, the second door switch 11b has a large rated capacity, for example, 5 amperes.

As can be seen from the above description, the second door switch 11b operates on and off in a normal state where the contacts of the first door switch 11a are not welded and no current can flow, and does not generate inductive noise. On the other hand, in a failure state in which the contacts of the first door switch 11a are welded, the first door switch 11a is always on and the second door switch 11b is in a state where current can flow, and for example, when the door 4 is opened, the second door switch 11b is When turned on, the second door switch 1 blows out the fuse 21.
A current flows through the second door switch 11b, and as a result, inductive noise is generated from the second door switch 11b. However,
This noise occurs only in an extremely rare situation such as a failure of the first door switch 11a. Therefore, the second door switch 11b and the third door switch 11c, which are housed in one switch case 13, receive almost no inductive noise, and as a result, the electronic control circuit 24 to which the third door switch 11c is connected receives no inductive noise. is hardly affected by.

In addition, the material of the switch case 13 mentioned above is the second material.
There is no need to match the rated capacity of 5 amperes of the door switch 11b. That is, the second door switch 11b
This is because current only flows in the rare situation where the contacts of the first door switch 11a are welded. Therefore, the material for the switch case 13 is a material with a small rated capacity of the third door switch 11c, for example, 00.1.
It only needs to be able to withstand amperage, and the switch case 13 can be made inexpensive.

In the above embodiment, the common substrate 9 has the first to fourth
Although the door switches 11a to 11d are installed as one unit, the second and third door switches 11b and 11c
The switch case 13 of is extended to serve as a common board,
In this extension part, the first and fourth door switches 11a,
11d may be attached integrally.

(G) Effects of the Invention According to the present invention, a door switch related to an electronic control circuit and other door switches are housed in one switch case so as to minimize deviations in operation timing based on door opening/closing. In the case where the latter door switch is installed, an appropriate door switch with a large rated capacity was selected, so that when the latter door switch is operated, there will be almost no inductive noise that would transmit through the former door switch and cause the electronic control circuit to malfunction. The switch case can be made of inexpensive materials.

[Brief explanation of drawings]

The drawing shows a microwave oven according to an embodiment of the present invention.
2 is a sectional view of a main part, FIG. 3 is a sectional view of a further main part, and FIG. 4 is a circuit diagram. 2...Heating chamber, 4...Door, 11a-11d...First
~4th door switch, 13...switch case, 1
7...Microwave supply circuit, 21...Power cutoff fuse, 23...Commercial power input section, 24...Electronic control circuit.

Claims (1)

[Claims] 1. An electronic device consisting of a heating chamber for storing food, a door for opening and closing the opening of this heating chamber, a heating energy supply means for supplying heating energy into the heating chamber, a microcomputer for controlling the drive of this supply means, etc. a control circuit, a commercial power input section, a power cutoff means, a first door switch means interposed between the input section and the supply means together with the cutoff means and linked to the opening and closing of the door, a first door switch means linked to the opening and closing of the door; a second door switch means for activating the power cutoff means when the first door switch means fails; a third door switch means linked to the opening/closing of the door and detected by the electronic control circuit; An electronically controlled cooking appliance characterized in that a door switch means is housed in one switch case.