JPH0518541A - Microwave oven - Google Patents

Abstract

PURPOSE:To provide a microwave oven wherein heating of a light-weight food is performed for a proper time corresponding to the amount of the food. CONSTITUTION:A microwave oven includes infrared transmitters on opposite sides of a heating chamber 3 at a predetermined height, and an infrared detector 6 for detecting infrared rays sent from the infrared transmitters 5. It further includes heating time control means 10 for controlling heating time based upon detection signals from the infrared detectors 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heating time control structure for a microwave oven.

[0002]

2. Description of the Related Art Usually, in heating time control for the same food in a microwave oven, the weight is detected and the heating time is set according to the weight.

[0003]

However, when the heating time is adjusted by the weight, for example, if the weight of the popcorn is very light, the heating time set is unreliable, and a small amount of popcorn is erroneously set. If it is heated for a long time, popcorn will generate kogation,
The bag burned causing a fire.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a microwave oven in which heating of lightweight food is performed for an appropriate time corresponding to the amount.

[0005]

According to the present invention, the microwave oven is provided with an infrared transmitter and an infrared detector for detecting infrared rays from the infrared transmitter at predetermined height positions on both sides of the heating chamber. The heating time control means for controlling the heating time by the detection signal of the infrared detector is provided.

[0006]

According to the present invention, when the height of the food stored in the heating chamber is equal to or higher than a predetermined height and the infrared rays are blocked by the food and the detection signal cannot be obtained, the heating time is set to be long. On the other hand, when the food height is small and the detection signal is obtained, the heating time is set to be short.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below. FIG. 1 is a front sectional view of the microwave oven of the present invention.
Reference numeral 1 is an exterior frame, in which a heating chamber 3 is provided,
The magnetron 2 is attached to the upper part of one side of the heating chamber 3. Below the heating chamber 3, a tray 4 on which the food S is placed is provided.

An infrared transmitter 5 for horizontally transmitting infrared rays is provided on the side of the opposing wall surface 9 in the heating chamber 3 at a height position of about 1/3 from below one side wall surface 8 of the heating chamber 3. An infrared detector 6 for detecting infrared rays from the infrared transmitter 5 is provided at a position on the opposite wall surface 9 facing the infrared transmitter 5. Then, as shown in FIG. 1, when the height of the food S exceeds the transmission height of the infrared rays, the infrared rays are blocked and the infrared detector 6 cannot obtain a detection signal. However, as shown in FIG. 2, the infrared detector 6 can obtain a detection signal when it is low.

Reference numeral 10 denotes a control section as a heating time control means composed of a microcomputer.
Signals from the infrared detector 6, a temperature sensor (not shown), and operation keys are given to 0, and the control unit 10 controls the operation of the magnetron 2 based on these signals. Next, the popcorn heating operation will be described with reference to the flowchart of FIG.

There are a large bag (3.50z) and a small bag (1.750z) in the popcorn for normal heating, and the microwave oven of this embodiment is provided with each automatic heating control program, and its operation program is , Is performed by pressing the popcorn key PK of the operation unit 7 shown in FIG. First, heating is started by pressing the Puff cone key PK, and when the heating time T reaches the popcorn pouch heating set time Ts, the presence or absence of an infrared detection signal is confirmed, and the detection signal is obtained as shown in FIG. If yes, stop heating and end the operation (step 1,
2, 3, 4).

On the other hand, if the detection signal is not obtained as shown in FIG. 1 for a large bag in step 3, heating is continuously stopped until the large bag heating set time Tm (step). 3, 5, 4). As described above, by using the infrared detection signal, the large and small bag of popcorn can be always heated for an appropriate time.

Next, with reference to FIGS. 5 and 6, the characteristic construction of the other portions of the above embodiment will be described. In this embodiment, the wind direction plate 14 attached to the upper part of the magnetron 2 for guiding the cooling air from the blower 12 to the magnetron 2 is made of a shape memory alloy. Normally, the magnetron anode temperature under load is about 200 degrees C. Since the temperature of the thermal limiter 15 portion installed on the magnetron 2 is low, there is a margin for the CUTOFF value of the thermal limiter 15, but there is no At the time of load, the magnetron anode temperature rises from 240 to 260 ° C, and there is no room. Therefore, when the magnetron 2 becomes hot, the wind direction plate 14 that normally extends to the blower 12 side is bent by a shape change as shown in FIGS. 5 and 6 to cool the thermal limiter 15. To avoid CUTOFF of the thermal limiter 15. This prevents the malfunction of the thermal limiter 15 when the popcorn is heated, which is close to no load.

Further, the characteristic construction of another embodiment will be described with reference to FIGS. In this embodiment, an opening 18 is provided on the upper and lower surfaces of the guide body 17 of the blower 12, and the opening 18 is formed.
The fuse holder 19 and the high-voltage condenser 20 are attached on the portions, and the blower 12 blows air to cool the heating elements efficiently.

[Brief description of drawings]

FIG. 1 is a front sectional view of a microwave oven of the present invention.

FIG. 2 is a sectional view of a main part of a heating chamber.

FIG. 3 is a flowchart for explaining the operation.

FIG. 4 is a front view of an operation unit.

FIG. 5 is a side sectional view of the microwave oven of the present invention.

FIG. 6 is a perspective view of a magnetron portion.

FIG. 7 is a side sectional view of another embodiment of the microwave oven of the present invention.

FIG. 8 is a perspective view of a guide body of a blower.

[Explanation of symbols]

 3 heating chamber 5 infrared transmitter 6 infrared detector 10 control unit (heating time control means)

Claims (1)

Claim: What is claimed is: 1. An infrared transmitter and an infrared detector for detecting infrared rays from the infrared transmitter are provided at predetermined height positions on both sides of the heating chamber, and the infrared detector is used for detection. A microwave oven comprising heating time control means for controlling the heating time by a signal.