JPH0112086Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a microwave oven having an operation panel equipped with a plurality of key switches with light sources, and in particular to a microwave oven that can prevent shortening of the life of the light source of the key switch. Regarding.

[Technical background of the invention]

A conventional microwave oven, for example, includes a magnetron drive circuit that drives a magnetron, a control device that includes a microcomputer that provides a drive command signal to the magnetron drive circuit according to a program stored in advance, and an input signal to the microcomputer. The applicant and others previously proposed an operation panel equipped with a plurality of key switches with light sources. Here, the operation panel 1 is
As shown in FIG. 1, a plurality of key switches, such as a microwave operating switch 1, are installed next to a door 2 that opens and closes the front opening of the microwave oven body.
0, oven operation switch 11, code selection number switch 1 for selecting the automatic cooking code
2. In addition to the start switch 13 and the clear switch 14, it is equipped with a display 15 for displaying the time and cooking time. and the oven operating switch 10 and the oven operating switch 1.
1. The code selection switch 12 and the start switch 13 have a light source such as a light emitting diode LED or electroluminescence EL on their heads to indicate the operating state.

In the above configuration, when the user turns on the power to cook, the microwave operation switch 1
0 and the oven operation switch 11 light up, when the user turns on either of the switches 10 and 11, the microcomputer in the control device enters the range or oven operation mode and turns on the predetermined position of the numeric switch 12. Turn it on. When the user turns on the lit numeric switch 12 and selects a cooking code, the predetermined automatic cooking mode is set in the microcomputer and the start switch 13 lights up. Turn on. As a result, the magnetron is operated by the magnetron drive circuit according to the cooking program stored in advance in the microcomputer, and the food is automatically heated. According to this type of microwave oven, each key switch on the operation panel 1 lights up in sequence according to the operating procedure stored in the microcomputer, so the user only has to turn on each key switch according to the lighting order. Therefore, there is an advantage that the microwave oven can be operated simply and accurately.

[Problems with background technology]

However, in this type of microwave oven, the range operation switch 10 or the oven operation switch 11 remains lit until the operation of the range or oven is completed, so the number keys 12 and other key switches do not light up as much. There were signs that the lifespan was shortened, such as longer time, uneven brightness, and loss of marketability.

[Purpose of invention]

The present invention has been made to eliminate the above-mentioned drawbacks of the prior art, and an object of the present invention is to provide a microwave oven that can extend the lighting life of the key switch.

[Summary of the idea]

In order to achieve the above object, the present invention extends the lighting life of a light source such as a key switch by providing a control device with a control means for limiting the lighting time of a key switch or the like.

[Example of idea]

Embodiments of the present invention will be described below with reference to the accompanying drawings. In the following drawings, the same elements as in FIG. 1 are given the same reference numerals.

FIG. 2 is an external view of the main parts of the microwave oven according to this embodiment. This microwave oven is different from the one shown in FIG. 1 in that the operation panel 1 is provided with a microphone 20 for a proximity detection sensor. This microphone 20 emits ultrasonic waves and receives reflected waves from the human in order to detect the approach of a human.

FIG. 3 is a schematic configuration diagram of an electric circuit installed in the microwave oven of FIG. 2. In Figure 3, 21
is a power transformer for power supply, and the AC voltage of this power transformer 21 is given to the control device 22. The control device 22 has a microcomputer equipped with a timer function for controlling the lighting time of keyswitches, etc., and gives a command signal to the magnetron drive circuit 23 according to a stored cooking program to operate the magnetron and display information. vessel 15
A time display command signal is given to the display 15 to display the time and cooking time. This control device 22
An input signal is given from the operation panel 1 and a proximity detection sensor control circuit 24 having an oscillation circuit and a reception circuit, and a mechanical or electrical switch 25 is turned on or off by the output signal of the control device 22 to turn on or off the power. The output voltage of the transformer 21 is applied or cut off to the light source power supply circuit 26. The light source power supply circuit 26 connects the key switches 10 to
It supplies lighting current to each of the light sources 13, and when an EL panel is used as each light beam of the key switches 10 to 13, it is constituted by a circuit that boosts the AC output voltage of the power transformer 21.

In the above configuration, when a user approaches the microwave oven to use the microwave oven, the ultrasonic waves emitted from the microwave oven 20 are reflected by the user and enter the microwave oven 20 again, and the approach is detected. The sensor control circuit 24 detects the approach of a person from the transmitted waves and received waves, and provides the detection signal to the control device 22. Then control device 2
2 gives an on command signal to the switch 25 to turn on the switch 25, so the output voltage of the power transformer 21 is given to the light source power supply circuit 26, and the output voltage of the power transformer 21 is boosted by this power supply circuit 26. A signal is applied to the operation panel 1. Then, the microcomputer in the control device 22 gives a lighting command signal to the operation panel 1 according to the stored operation procedure. As a result, the range operation switch 10 and the oven operation switch 11 are first turned on as in the conventional case, so the user turns on either switch 10 or 11. Then, this ON signal is given to the control device 22, and the microcomputer between the control devices 22 enters the range operation mode or the oven operation mode and lights up a predetermined part of the number switch 12, so that the user can read the number that is lit. When the switch 12 is turned on and a cooking code is selected, a predetermined automatic cooking mode is set in the microcomputer and the start switch 13 is turned on. Therefore, when the user turns on the start switch 13, the magnetron drive circuit 23 operates according to the cooking program stored in the microcomputer, and the food is automatically heated. In this embodiment, the control device 22 has a timer function, and after a predetermined period of time has elapsed after the range operation switch 10 and oven operation switch 11 are turned on, it gives a command signal to turn off the lights to the switches 10 and 11. It is configured to force the lights to turn off. Therefore, the lighting time of the switches 10 and 11 can be shortened compared to the conventional case, and not only can their lifespan be extended, but also electric power can be saved. As a means for achieving the timer function, a software timer is used to select the switch 10, 11 after the user selects the switch 10, 11.
Switches 10 and 11 can be turned off by the user, or by using a timer such as a counter.
When a predetermined period of time has elapsed after the selection of switch 1
A configuration such as forcibly turning off lights 0 and 11 can be adopted. In the above embodiment, only the range operation switch 10 and the oven operation switch 11 are forced to turn off after a predetermined period of time, but the same can be applied to the other key switches 12 and 13. 12,1
This makes it possible to extend the life of the light source described in No. 3.

FIG. 4 shows the main parts of an electric circuit according to another embodiment of the present invention. In this circuit, the switching transistor 25' is turned on and off at predetermined times according to a program stored in advance by the control device 22, thereby converting the AC output voltage of the power transformer 21 into DC. The DC voltage applied to 26' is applied or cut off. The light source power supply circuit 26' includes a switching transistor TR, a pulse transformer T and
It is composed of an inverter consisting of an RC negative bias circuit, etc. When the switching transistor 25' is turned on, the switching transistor TR is turned on, and then the output of the pulse transformer T is fed back through the RC negative bias circuit to perform switching. The transistor TR is reverse biased and turned off, and these operations are repeated in sequence to convert the input DC voltage to a predetermined AC voltage, which is applied to the operation panel 1. On the other hand, when the switching transistor 25' is turned off based on the command signal from the control device 22, the switching transistor TR is turned off, the operation of the inverter is stopped, and the power supply to the operation panel 1 is interrupted. In this embodiment, the timer function of the control device 22 turns on the power to keep the microwave oven ready for use after the user wakes up in the morning, for example, according to a pre-stored program. When the time comes, the switching transistor 25' is turned on to supply power to the operation panel 1, and after a predetermined time has elapsed, the switching transistor 25' is turned off to cut off the power supply to the operation panel 1. In this way, the life of the light source of the key switches 10 to 13 can be extended and the power consumption can be saved.

[Effect of idea]

As explained above, according to this invention, the control device is provided with means for forcibly turning off the lights of a plurality of key switches on the operation panel after a predetermined period of time has elapsed after lighting them, thereby shortening the lighting time of the key switches and reducing their lifespan. It is possible to extend the period of time, and also to reduce unnecessary power consumption for lighting.

[Brief explanation of drawings]

Fig. 1 is an external view of the main parts of a conventional microwave oven, Fig. 2 is an external view of the main parts of a microwave oven according to an embodiment of the present invention, and Fig. 3 is installed in the microwave oven of Fig. 2. FIG. 4 is a block diagram of the main parts of an electric circuit according to another embodiment of the present invention. 1...Operation panel, 10, 11, 12, 13,
14...Key switch, 22...Control device, 2
5, 25'...Switch, 26, 26'...Light source power supply circuit.

Claims (1)

[Claims for Utility Model Registration] A control device having a magnetron drive circuit that drives a magnetron, a microcomputer that provides a drive command signal to the magnetron drive circuit according to a program stored in advance, and an input signal to the microcomputer. an operation panel on which a plurality of key switches each having a plurality of light sources are arranged, and the plurality of key switches are sequentially turned on by the control device in accordance with a pre-stored operating procedure. A microwave oven characterized in that the control device is provided with means for forcibly turning off the key switch after a predetermined period of time has elapsed after the key switch is turned on.