JPH0579883B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a microwave oven that allows food to be cooked under appropriate conditions by accurately measuring the weight of food placed on a turntable.

[Technical background of the invention and its problems]

As shown in FIG. 3, this type of microwave oven includes an oven 2 and a machine room 3 in a box-shaped casing 1, and electrical parts such as a transformer 4, a capacitor 5, and a magnetron 6 in the machine room 3. As shown in FIG. 4, heaters 7 are provided in two stages in the oven 2, and a turntable 8 provided in the oven 2 is rotated by a motor 9 to heat and cook food 10 placed on the turntable 8. That's what I do.

On the other hand, the motor 9 is attached with a weight sensor 11 that uses a spring means to detect the weight of the food 10. This weight sensor 11 is provided with a fixed electrode and a movable electrode attached to a spring means that is displaced under load, facing each other, and changes in capacitance occurring between the fixed electrode and the movable electrode. By sending a signal W corresponding to the frequency detected according to the frequency to the microcomputer 12 and processing it, the weight of the food 10 is calculated, and the cooking time corresponding to the weight of the food 10 is set to properly heat and cook. I am trying to do this.

However, in the microwave oven of the above type, when the food 10 is cooked by the heater 9, the oven 2 is in a high temperature state during cooking. Therefore, the motor 9 disposed below the oven 2
The weight sensor 11 attached to the motor 9 is also placed in a high temperature atmosphere due to the influence of the temperature of the oven 2 heated to a high temperature, and is used as a detection means for the weight sensor 11. Since the spring means provided with the movable electrode is displaced under the influence of the temperature, the zero point shifts, and there is a problem that an error occurs in the detection signal of the weight sensor 11.

Therefore, when performing heating cooking using the heater 9, first, after preheating the oven 2,
When measuring the weight of food, an error occurs in the detection signal of the weight sensor 11 due to the influence of temperature, and as the zero point shifts, the cooking time set based on this detected weight also deviates, making it difficult to measure the food. The problem was that it could not be cooked properly.

[Purpose of the invention]

The present invention has been made in view of the above points, and
To provide an oven range capable of accurately cooking and heating food by correcting the zero point of a weight sensor at the end of preheating during oven cooking to accurately measure the weight of food.

[Summary of the invention]

The microwave oven of the present invention includes a turntable provided inside an oven having a heater, and in which food placed on the turntable is heated and cooked, the turntable is connected to the turntable via a rotating shaft. A motor that rotates and drives the heater, a weight sensor attached to the motor that detects the load applied to the rotating shaft of the motor, and a cooking time that is set according to the weight detection signal of the weight sensor and controls whether to turn on or off the heater. The present invention is characterized in that the food is heated and cooked by the heater after zero point correction of the weight sensor is performed based on the weight detection signal measured at the end of preheating by the heater.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, the same members as in FIG. 4 are given the same reference numerals.

The weight sensor 11 is integrally attached to the rotating shaft of the motor 9 that rotates the turntable 8, and the weight sensor 11 has a fixed electrode and a movable electrode attached to a spring means that is displaced under load. By sending a signal W corresponding to a frequency detected according to a change in capacitance generated between a fixed electrode and a movable electrode that are arranged opposite to each other to the microcomputer 12 for calculation processing, the food 10 The weight of the food 10 is calculated, and a cooking time corresponding to the weight of the food 10 is set to properly heat and cook the food 10. This microcomputer 12 has a function as a means for controlling energization/disconnection of the heater based on the cooking time calculated according to the weight of the food 10.

The weight sensor 11 is configured to perform zero point correction to determine that the weight value is zero (0 g) by transmitting the detected frequency in a state where a predetermined load is applied to the microcomputer 12 for processing. has been done.

Furthermore, when the upper and lower heaters 7, 7 are energized and the temperature inside the oven rises, the weight sensor 11 is affected by the thermal influence from the oven 2.
As shown in FIG. 2, the frequency f based on the first detection signal has a value that varies by Δf with respect to the frequency F0, which is the zero point, at the internal temperature T during preheating control. Therefore, the zero point frequency of this weight sensor 11 drifts under the influence of the oven temperature, and this acts as an error in weight detection of the weight sensor 11.

Therefore, the frequency (F0 - Δf) detected during preheating control immediately before the end of preheating by the heater is corrected as the zero point of the weight sensor. This zero point correction is performed by sending a signal W1 corresponding to the fluctuation frequency Δf of the weight sensor 11 to the microcomputer 12,
The zero point correction is completed by processing W-W1 as the zero point setting value.

Next, the action will be explained.

To cook the food 10 using a heater,
The heater is activated to preheat the oven 2 until the internal temperature reaches T without food 10 being placed therein. Then, the weight sensor 11 undergoes a temperature drift by Δf with respect to the set frequency F ₀ at the zero point due to the thermal influence of the temperature inside the oven. In other words, since the set frequency of the weight sensor 11 is F ₀ −Δf, immediately before the end of preheating, a signal corresponding to this variation Δf is sent to the microcomputer 12, the zero point correction of the weight sensor 11 is executed, and the setting is performed again. do.

When the preheating is completed, the food 10 is placed in the oven 2 and the heater is energized. At this time, the weight sensor 11 has already completed the zero point correction corresponding to the cooking control temperature T immediately before the end of preheating, so the weight of the food placed on the turntable 8 is accurately measured, and the weight sensor The cooking time set based on the detection signal is also set accurately, and the food can be cooked under appropriate conditions.

Note that if you place a separate round top on the turntable and cook food placed on this round top, such as a cake, the weight sensor measurement value is calculated by subtracting the weight of the round top, and this The cooking time is calculated based on the food weight value and constants set inside the microcomputer.

〔Effect of the invention〕

As described above, according to the present invention, the zero point correction of the weight sensor is executed at the end of preheating.
The weight of the food placed in the oven for subsequent cooking can be accurately measured, the cooking time suitable for the food can be set correctly, and the food can be cooked with correct heat.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram of the microwave oven according to the present invention, Fig. 2 is a diagram showing the temperature drift of the weight sensor due to changes in the internal temperature, and Fig. 3 is a perspective view showing a part of the conventional microwave oven broken down. FIG. 4 is a schematic diagram of a conventional microwave oven. 2...Oven, 8...Turntable, 9...
...Motor, 10...Food, 11...Weight sensor,
12... Microcomputer, f... Frequency,
Δf...Drift value.

Claims (1)

[Claims] 1. A turntable is provided inside an oven having a heater, and in an oven range for cooking food placed on the turntable, a motor is connected to the turntable via a rotating shaft and rotates the turntable; A weight sensor attached to the motor detects the load applied to the rotary shaft of the motor, and a means for setting cooking time and controlling energization/disconnection of the heater according to the weight detection signal of the weight sensor. A microwave oven characterized in that food is cooked by a heater after zero point correction of a weight sensor is performed based on a weight detection signal measured at the end of preheating.