JPS6143832B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention detects the weight of food in a microwave oven and automatically controls microwave oscillation.

In a microwave oven, food cannot be cooked properly unless the output level and irradiation time of the microwave are changed depending on the weight of the food. Therefore, it is extremely convenient for microwave oven users to automatically detect the weight of food and control microwave oscillation according to the weight.

There are various methods for weight detection, and some methods allow for very accurate measurements. However, cooking in a microwave oven does not require such highly accurate weight measurement. Most microwave ovens use a turntable, and if the relationship between the rotational speed of the table and the weight is used for measurement, the weight can be measured at a lower cost and with sufficient accuracy for microwave cooking. This was done with a focus on the ability to do this.

The figure shows an embodiment of the present invention, in which 1 is a turntable placed on the open bottom of a microwave oven, on which food 2 is placed and rotated; 3 is a motor that rotates the table;
4 is a drive circuit that drives the motor. The turntable 1 is made of a ferromagnetic material such as iron, and has annular recesses 5, 5, . . . carved at regular intervals on the back edge thereof. Reference numeral 6 denotes a detection means consisting of a magnetoresistive element disposed close to the edge of the back surface of the turntable 1, and this means generates an electric pulse each time the recess 5 approaches as the turntable 1 rotates. 7 is a keyboard; 8 is a microcomputer (hereinafter referred to as μ) that controls the drive circuit 4 and magnetron oscillation circuit 9 according to signals from the keyboard and the detection means 6
COM).

The operation of such a microwave oven is as follows. After placing the food 2 on the turntable 1, when a start signal is given from the keyboard 7, the μCOM 8 first energizes the drive circuit 4 to rotate the turntable 1. The speed of such rotation depends on the weight of the food product 2. Therefore, the μCOM 8 calculates the rotational speed of the turntable 1, in other words, the weight of the food by counting the number of pulses input from the detection means 6 per unit time, and based on this calculates the rotation speed of the turntable 1, which is more suitable than the pre-stored conversion formula. After calculating and setting the magnitude of the microwave output and/or the microwave irradiation time, the microwave oscillation circuit 9 is controlled based on the set conditions.

In the above embodiment, a ferromagnetic one was used as the turntable 1, but other materials such as glass or porcelain may be used, and ferromagnetic pieces may be embedded in each recess 5 on the back edge. Alternatively, a photodetecting element can be used as the detection means 6 without such embedding.

Thus, according to the present invention, the weight of the food is detected and the microwave oscillation is automatically controlled, which is extremely convenient.Moreover, the turntable provided in the microwave oven is used to detect the weight. Since this method is carried out, it can be constructed at low cost.

[Brief explanation of the drawing]

The figure is a block circuit diagram of an embodiment of the present invention.
6 is a turntable, 6 is a detection means, and 8 is a microcomputer.

Claims (1)

[Claims] 1. A microwave oven characterized by being provided with a detection means for detecting the rotational speed of a turntable on which food is placed and rotated, and controlling microwave oscillation according to the output of the detection means.