JPH01246786A - Cooking apparatus - Google Patents

Abstract

PURPOSE:To simplify the construction of a switch interlocked with opening/ closing of a door, by forming a current supply path to a lamp through a normally closed contact of an interlock switch when door is opened, and establishing the same through a normally open contact during cooking. CONSTITUTION:When the door to a heating chamber is opened, a current supply path is formed through a fuse 2, a magnetron thermal 3, an interlock monitor switch 4c, and the normally closed contact of a primary interlock switch 40a, and a lamp 11 is lighted up. When the door is shut, the interlock monitor switch 4c is turned off while the primary interlock switch 40a is changed over, and thus the lamp 11 is turned off. If cooking is started from an operational part 23 after shutting the door, a control part 20 actuates relays 21, 22, and turning-on of contacts 21a, 22a constitutes the current supply path through the abovementioned fuse 2, magnetron thermal 3, contact 21a, and the normally open contact of the primary interlock switch 40a to cause lighting-up of the lamp 11, which goes out with the contact 21a being turned off when the cooking is finished.

Description

[Detailed description of the invention] [Purpose of the invention] (Industrial application field) The present invention relates to a cooking appliance such as a microwave oven.

(Prior Art) A cooking appliance such as a microwave oven is equipped with a lamp for illuminating the heating room, and the lamp is turned on during cooking so that the doneness of food can be visually checked from outside.

Furthermore, a lamp is lit even when the heating chamber door is opened, making it easier to take food in and out.

An example of the electric circuit of such a microwave oven is shown in FIG.

1 is a commercial AC power supply, and the power supply 1 is connected to a fuse 2° magnetron thermal 3. A high frequency oscillation circuit 5 is connected via a primary interlock switch 4a, a relay contact 22a, a relay contact 21a, and a secondary interlock switch 4b.

The high frequency oscillation circuit 5 includes a secondary coil 6a of a high voltage transformer 6.
The anode and cathode of the magnetron 9 are connected to the secondary coil 6b of the high voltage transformer 6 through a half-wave voltage doubler rectifier circuit consisting of a high voltage capacitor 7 and a high voltage diode 8. Further, the anode of the magnetron 9 is grounded, and the heater (cathode) is connected to the secondary coil 6C of the high voltage transformer 6.

Also, fuse 2 is connected to power supply 1. Magnetron thermal 3.
A lamp (interior lamp) 11 for illuminating the heating room is connected via the normally closed contact of the lamp operation switch 10.

Note that regarding the lamp 11, the fuse 2. Magnetron thermal 3. Brimary interlock switch 4a
, are also connected to the power source 1 via the relay contact 22a and the normally open contact of the lamp operation switch 10.

The lamp operation switch 10 is actuated when the door is closed, and the normally open side contact is turned on, but when the door is opened, the lamp operation switch 10 is deactivated and the normally closed side contact is turned on, as shown in the figure.

Furthermore, fuse 2 is connected to power supply 1. magnetron thermal 3
．． A magnetron cooling fan motor 12 is connected via a brake interlock switch 4a.

On the other hand, a control section 20 is connected to the power supply 1 via a step-down transformer 13.

The control section 20 is made up of a microcomputer and its peripheral circuits, and controls the entire microwave oven. This control section 20 includes a door oven monitor switch 4d, a first relay 21 for heating control, and a second relay 21 for heating control.
Relay 22. The operating section 23 is connected.

Therefore, when the door is opened to put food into the heating chamber, the normally closed contact of the lamp operation switch 10 is turned on, and the lamp 11 is turned on. When the door is closed, the lamp operation switch 10 is switched to turn on its normally open side, and the lamp 11 is turned off.

When cooking starts after the door is closed, the lamp 11 is turned on by turning on the contact 22a based on the energization of the relay 22, turning on the interlock switch 4a, and turning on the normally open side contact of the lamp operation switch 10.

When the cooking is finished, the contact 22 is activated based on the de-energization of the relay 22.
The lamp 11 is turned off by turning off the switch a.

When the door is opened to take out the food, the normally closed contact of the lamp operation switch 10 is turned on and the lamp 11 is turned on.

By the way, so far we have described a microwave oven in which the lamp 11 is controlled by the lamp operation switch 10, but as shown in FIG. Some control the.

That is, the lamp 11 is connected to the fuse 2. Magnetron thermal 3. It is connected to the power source 1 via a relay contact 21a. Furthermore, the magnetron cooling fan motor 12 is connected to the fuse 2. Magnetron thermal 3. Brimary interlock switch 4a, relay contacts 22a, 21a
It is connected to power supply 1 via.

As shown in FIG. 7, the control unit 20 includes a micro combinator 30. Relay drive circuit 31. It has a door open detection circuit 32. The door open detection circuit 32 detects the opening of the door using the door oven monitor switch 4d, and upon detection, it gives a command to that effect to the microcomputer 30, which is the main control unit, and also sends a drive command to the relay drive circuit 31. It is designed to be given to

Therefore, when the door is opened to store food in the heating chamber, the door oven monitor switch 4d is turned off, and in response, a drive command is given from the door open detection circuit 32 to the relay drive circuit 31. This allows relay 2
1 is energized, the contact 21a is turned on, and the lamp 11 is lit. In this case, since the contact 22a remains off, the high frequency oscillation circuit 5 does not operate.

When the door is closed, the door oven monitor switch 4d is turned on, and the drive command from the door open detection circuit 32 to the relay drive circuit 31 is released. This results in
The relay 21 is deenergized, the contact 21a is turned off, and the lamp 1 is turned off.
1 goes out.

When cooking starts after the door is opened, the relay 21 is energized and the lamp 11 is turned on.

When cooking is completed, relay 21 is deenergized and lamp 1 is turned off.
1 goes out.

When the door is opened to take out the food, the relay 21 is energized by a drive command from the door open detection circuit 32, and the lamp 11 is turned on.

(Problems to be Solved by the Invention) However, in the case of using the lamp operation switch 10 as shown in FIG. 5, there are many switches that respond to the opening and closing of the door, which increases the cost and complicates the configuration. The disadvantage is that the number of assembly steps increases.

on the other hand,'! In the case where the lamp 11 is controlled by the door oven monitor switch 4d and the main relay 21 as shown in Fig. s6 and Fig. 7, the mounting position of the door oven monitor switch 4d is the primary interlock switch 4a or the secondary interlock switch. Since the door oven monitor switch 4b is located adjacent to the installation position of the door oven monitor switch 4b, noise from the power supply line is caused by the door oven monitor switch 4 as shown by the broken line arrow 1 in FIG.
It may enter the door open detection circuit 32 via d, flow to the microcomputer 3o, or further flow to the microcomputer 30 via the relay drive circuit 31. In other words, microcomputer 3
0, there are two paths through which noise can enter, and this has the disadvantage that the microcomputer 30 is likely to malfunction.

This invention was made in view of the above circumstances,
The purpose of this is to be able to accurately control lamps for heating indoor lighting even though the number of switches that respond to the opening and closing of the door is small, thereby reducing costs and simplifying the configuration. To provide a highly reliable cooker free from malfunctions caused by noise.

° [Structure of the invention] (Means for solving the problem) A high-frequency oscillation circuit, a lamp for illuminating the heating chamber, and a bidirectional contact type that operates when the door of the heating chamber is closed and deactivates when it is opened. an interlock switch; an interlock monitor switch that turns off when the door is closed and turns on when the door is opened;
A first relay and a second relay for heating control are provided, and the high frequency oscillation circuit is connected to a fuse, a contact point of the first relay, and a second relay.
The interlock monitor switch is connected to the power supply through the fuse and the normally open contact of the interlock switch, and the lamp is connected to the power supply through the fuse and the normally open contact of the interlock switch. A first relay contact and a normally open contact of an interlock switch are connected to a power source, and the lamp is a fuse and an interlock monitor switch.

Connect to the power supply via the normally closed contact of the interlock switch.

(Function) When the door is opened, an energizing path to the lamp is formed via the fuse, interlock monitor switch, and normally closed contact of the interlock switch. When cooking, use the first fuse
An energizing path to the lamp is formed through the contacts of the relay and the normally open contact of the interlock switch.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings. In the drawings, the same parts as in FIGS. 5 to 7 are designated by the same reference numerals, and their explanations will be omitted.

As shown in FIG. 1, the high frequency oscillation circuit 5 is connected to the fuse 2.
Magnetron thermal 3. Relay contact 21a, secondary interlock switch 4b.

It is connected to the power source 1 via the relay contact 22a and the normally open contact of the primary interlock switch 40a.

Connect interlock monitor switch 4c to fuse 2° magnetron thermal 3. The primary interlock switch 40a is connected to the power supply via the normally open contact.

Connect lamp 11 to fuse 2. Magnetron thermal 3. Relay contact 21a, brake interlock switch 4
Connect to the power supply 1 via the normally open side contact of 0.

Furthermore, regarding the lamp 11, fuse 2° magnetron thermal 3. It is also connected to the power source 1 through the normally closed contacts of the interlock monitor switch 4c and the automatic interlock switch 40a.

The magnetron cooling fan motor 12 is connected to the fuse 2. Magnetron thermal 3. Relay contact 21a, secondary interlock switch 4b.

The primary interlock switch 40 is connected to the power supply 1 through the normally open contact.

As shown in FIG. 2, the control section 20 has a microcomputer 50 instead of the conventional microcomputer 30, and a relay drive circuit 31 and a door open detection circuit 32 are connected to the microcomputer 50.

That is, when the microcomputer 50 receives a command to open the door from the door open detection circuit 32, it gives a drive command to the relay drive circuit 31 in response to the command.

Next, the operation in the above configuration will be explained.

When the door is opened to place food in the heating chamber, fuse 2. Magnetron thermal 3.
Interlock monitor switch 4c.

An energizing path to the lamp 11 is formed through the normally closed contact of the primary interlock switch 40a. As a result, the lamp 11 is turned on.

Then, when the door is closed, the interlock monitor switch 4C is turned off and the blind interlock switch 40a is switched, so that the lamp 11 is turned off.

After opening the door, a desired cooking time is set using the operating section 23, and an operation to start cooking is performed. Then, control section 2
0 energizes the relays 21 and 22, and the high frequency oscillation circuit 5 operates by turning on the contacts 21a and 22a. In other words, cooking begins.

During this cooking, as shown in Fig. 4, fuse 2° magnetron thermal 3. An energizing path to the lamp 11 is formed through the contact 21a and the normally open contact of the primary interlock switch 40a. As a result, the lamp 11 is turned on.

When the set cooking time has elapsed, the control unit 20 activates the relay 21.
Deactivate 22. In other words, the operation of the magnetron 5 is stopped, and the cooking ends.

At the end of this cooking, the lamp 11 is turned off by turning off the contact 21a.
goes out.

When the door is opened to take out the food, the lamp 11 is turned on by the energizing path shown in FIG.

In this way, although the number of switches that respond to the opening and closing of the door is as small as four, it is possible to accurately control the lamp 11 for lighting the heating room.

Therefore, cost reduction and configuration simplification can be achieved.

Moreover, in the control section 20, the relay drive circuit 3
1 is limited to the signal from the microcomputer 50, the path through which the noise transmitted to the door open monitor switch 4d can enter the microcomputer 50 is through door open detection, as shown by the broken line arrow in FIG. It is only from the circuit 32 that it becomes difficult to malfunction. In other words, credibility is improved.

In addition, if the blind interlock switch 40a has a welding failure, a short circuit is formed to the fuse 2 via the interlock monitor switch 4c, and the fuse 2
is fused. This is also the case with conventional circuits, but in the present invention, when a welding failure occurs in the relay contact 21a, the fuse 2 is connected to the fuse 2 via the normally closed contact of the primary interlock switch 40a to short circuit the relay contact 21a. is formed, making it even safer.

Note that the present invention is not limited to the above-mentioned embodiments, and various modifications can be made without changing the gist.

[Effects of the Invention] As described above, according to the present invention, there is provided a high-frequency oscillation circuit, a lamp for illuminating the heating chamber, and a bidirectional contact type that operates when the door of the heating chamber is closed and deactivates when it is opened. an interlock switch, an ink monitor switch that is turned off when the door is closed and turned on when the door is opened, and a first relay and a second relay for heating control. Relay contact, second relay contact.

Connect the interlock monitor switch to the power supply via the normally open contact of the interlock switch, and connect the interlock monitor switch to the fuse,
Fuse the lamp by connecting it to the power source through the normally open side contact of the interlock switch.

Since the contact of the first relay and the normally open contact of the interlock switch are connected to the power supply, and the lamp is connected to the power supply through the fuse, the interlock monitor switch, and the normally closed contact of the interlock switch, Although the number of switches that respond to the opening and closing of the door is small, it is possible to precisely control the lamps used to illuminate the heating room.This reduces costs and simplifies the configuration, and there is no need to worry about malfunctions caused by noise. We can provide a highly reliable cooker.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the configuration of an electric circuit in one embodiment of the present invention, FIG. 2 is a diagram showing the configuration of the main part of the control section in the same embodiment, and FIGS. 3 and 4 are respectively in the same embodiment. FIGS. 5 and 6 are diagrams showing the configuration of the electric circuit of a conventional microwave oven, respectively. FIG. 7 is a diagram for explaining the operation of the conventional microwave oven, and FIG. 7 is the configuration of the main part of the control section in FIGS. FIG. 1... Commercial AC power supply, 40a... Blank interlock switch, 4b... Secondary interlock switch, 4C... Increment monitor switch, 4d... Door oven monitor switch, 5...
High frequency oscillation circuit, 11... lamp, 20... control section. Applicant's agent Patent attorney Takehiko Suzue Figure 2 Figure 3

Claims (1)

[Claims] A high-frequency oscillation circuit, a lamp for lighting the heating room, a bidirectional contact type interlock switch that is activated when the heating chamber door is closed and deactivated when it is opened, and a bidirectional contact type interlock switch that is turned off when the door is closed and is turned off when it is opened. is an interlock monitor switch that turns on,
Equipped with a first relay and a second relay for heating control,
The high frequency oscillation circuit is connected to a power source via a fuse, a contact of a first relay, a contact of a second relay, and a normally open contact of an interlock switch, and the interlock monitor switch is connected to a normally open side of the fuse and interlock switch. the lamp is connected to a power source through a side contact, and the lamp is connected to a power source through a fuse, a contact of a first relay, and a normally open side contact of an interlock switch; A cooking appliance characterized in that it is connected to a power source through a normally closed contact of a switch.