JPS60256726A - Cooker - Google Patents

Abstract

PURPOSE:To increase reliability in an automatic cooker controlled by a microcomputer program, by constituting the cooker in such a manner that the weight of food to be cooked is sensed as the change in inductance, the weight data is processed, and a cooking program is set for the food. CONSTITUTION:A food material to be cooked is placed on a shelf rack 2 and the kind of food and the kind of cooking are input into an operating part 12. The weight of food is sensed by a weight sensor 4, which has an inductance variable mechanism 20 and which outputs the change in inductance as frequency in accordance with the weight of food. The frequency signal is output into a microcomputer 11. The weight of food is determined by a microcomputer 11 from a frequency-weight condition. A cooking program is set based on the weight being calculated, and from the kind of food and the kind of cooking which have already even input. With such a constitution, the weight can be correctly detected without being affected by the noise from outside, as a result, reliability in the titled automatic cooker can be increased.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field of the Invention) The present invention relates to a cooking appliance that automatically performs cooking based on a cooking program.

[Technical background of the invention and its problems]

Conventionally, a cooking device such as a microwave oven is equipped with a microcomputer, and a cooking program, such as a cooking time, is set according to the weight of the food to be cooked, which is input by operating a key on an operation unit, and the cooking time is set based on the set cooking time. There are some that perform automatic cooking. However, in such a microwave oven, it is necessary for the user to weigh the food to be cooked using a scale before cooking, which is very troublesome for the user.

As an alternative to this, some devices are equipped with a weight detector that automatically detects the weight of the food to be cooked when it is placed in the heating chamber, and sets the cooking time in accordance with the detected weight. However, in this case, the weight detector is an expensive load cell (for example, used in electronic digital scales).
(An element that converts the strain caused by weight into an electrical signal)
Moreover, since the output signal of the load cell is an analog signal, an A/D is used as input to the microcomputer.
A disadvantage was that an (analog/digital) converter was required, which resulted in high cost.

In addition, load cells have the disadvantage that they are susceptible to external noise such as radio waves because their output signals are very small.

(Object of the invention) This invention was made in view of the above circumstances.
The purpose of this is to accurately detect the weight of the food to be cooked without increasing costs or being affected by external noise, thereby ensuring proper cooking at all times. Our goal is to provide a highly reliable cooking device.

[Summary of the invention]

This invention provides a weight detector that detects the weight of the food to be cooked as a change in inductance, sets a cooking program according to the output of this weight detector, and automatically cooks based on the set cooking program. be.

(Embodiment of the Invention) An embodiment of the invention will be described below with reference to the drawings.

In FIG. 1, reference numeral 1 denotes a heating chamber, and within this heating chamber 1 is provided a shelf board 2 on which food to be cooked is placed. The approximate center of the back surface of this shelf board 2 is connected to a weight detector 4 via a shaft 3 passing through the bottom surface of the heating chamber. This weight detector 4 detects the weight hanging on the shelf board 2 as a change in inductance, converts this change in inductance into a frequency, and outputs the frequency. Further, a high frequency radio wave irradiation port 5 is formed on the ceiling surface of the heating chamber 10, and one end of a waveguide 6 is communicated with the irradiation port 5. A magnetron 7 is attached to the outer periphery of the other end of the waveguide 6, and an antenna 7a of the magnetron 7 is introduced into the waveguide 6.

Thus, the output of the weight detector 4 is input to the microcomputer 11 of the control section 10. The control unit 10 consists of a microcomputer 11 and its peripheral circuits,
A program such as a cooking time is set in accordance with commands from the operation unit 12 and the output of the weight detector 4, and automatic cooking is performed by driving and controlling the relay 14 based on the set cooking time. Information is displayed on the display unit 13. On the other hand, 15 is a commercial AC power source, and the magnetron 7 is connected to this power source 15 via a relay contact 14a and a transformer 16.

Here, the specific configuration of the weight detector 4 will be explained with reference to FIGS. 2 and 3. First, the weight detector 4 has a variable inductance mechanism 20 . The variable inductance mechanism 20 includes a magnetic core 21a made of ferrite or the like, a winding 22 wound around the magnetic core 21a, and a magnetic core 21a made of ferrite or the like.
A guide pin 24.24 vertically movably inserted into the pin insertion hole 23.23 of 1a, a magnetic core 21b fixed to the upper end of the guide bin 24.24, and a magnetic core 21b provided around the guide bins 24, 24. The magnetic core 21b consists of springs 25, 25, etc. that apply a biasing force in the upward direction shown in the figure.
The shaft 3 is connected to the upper surface of the . Therefore, when the food to be cooked is placed on the shelf board 2, the magnetic core 21b moves down against the biasing force of the springs 25, 25, and the magnetic core 21b
The gap d between the magnetic core 21b and the magnetic core 21b becomes smaller, thereby changing the inductance of the winding 22.

That is, the number of turns of the winding 220 is N, and the constant determined by the material, structure, and dimensions of the magnetic circuit is K1. K2
Then, the following relationship approximately holds true between the inductance L of the winding 22 and the gap d.

L=N2/(k1·d+K2) That is, as the weight of the food to be cooked increases, the gap d becomes smaller and the inductance L of the winding 22 increases.

Furthermore, a resonance capacitor 31 is connected in parallel to the winding 22, and the inductance of the winding 22 and the capacitor 3
A resonant circuit is configured with a capacitance of 1. An inverting amplifier 32 is connected to this resonant circuit, and L
A C oscillation circuit is configured. The oscillation frequency f of this oscillation circuit
is expressed by the following formula.

In other words, if the weight of the food to be cooked is large and the inductance L of the winding 22 is large, the oscillation frequency f will be low; conversely, if the weight of the food to be cooked is small and the inductance L of the winding 22 is small, the oscillation frequency f will be low. The frequency f becomes higher.

Note that 33 and 34 are capacitors for stabilizing oscillation.

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

The power is turned on, the food to be cooked is placed on the shelf board 2 in the heating chamber 1, and the type of food to be cooked or the content of cooking is set using the operation unit 12. At this time, a signal with a frequency corresponding to the weight of the food to be cooked is supplied from the weight detector 4 to the microcomputer 11. Microcomputer 11
determines the frequency of the signal supplied from the weight detector 4, and further compares the determined frequency with a preset frequency-weight condition to determine the weight of the food to be cooked. Then, the microcomputer 11 sets a cooking program, for example, a cooking time, according to the determined weight and the type of food to be cooked or the content of cooking set on the operation unit 12.

When the user performs a cooking start operation using the operation unit 12, the microcomputer 11 operates the relay 14 for the set cooking time and causes the magnetron 7 to oscillate. In other words, dielectric heating is performed using high-frequency radio waves.

In this way, the weight detector 4 that detects the weight of the food to be cooked as a change in inductance and outputs a signal with a frequency corresponding to the change in inductance is provided, and the frequency of the signal output from this weight detector 4 is Since the weight of the food to be cooked is determined based on the frequency signal that is less affected by external noise, it is possible to accurately detect the weight of the food to be cooked. This allows for proper cooking at all times.

In addition, since the weight detector 4 employs a simple variable inductance mechanism 20 mainly consisting of magnetic cores 21a and 21b and a winding 22, there is no increase in cost.
Moreover, reliability can be improved. Furthermore, since the signal input from the weight detector 4 to the microcomputer 11 can be performed directly without using an A/D converter as in the prior art, costs can also be reduced in this respect.

In the above embodiment, an LC oscillation circuit is configured in the weight detector 4 to convert the change in inductance based on weight into a frequency and supply it to the microcomputer 11, but it is not necessary to do so. For example, L
An AC bridge circuit may be configured in place of the C-shooting circuit to convert changes in inductance based on weight into voltage and supply it to the microcomputer 11.

In addition, the present invention is not limited to the above-mentioned embodiments, and it goes without saying that various modifications can be made without changing the gist.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to accurately detect the weight of food to be cooked without increasing costs or being affected by external noise. It is possible to provide a highly reliable cooking device that enables cooking.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention; FIG. 1 is an overall configuration diagram, FIG. 2 is a configuration diagram of a variable inductance mechanism in a weight detector, and FIG. 3 is a configuration of an electric circuit of the weight detector. It is a diagram. DESCRIPTION OF SYMBOLS 1... Heating chamber, 4... Weight detector, 7... Magnetron, 10... Control part, 11 Microcomputer, 20... Inductance variable mechanism, 21a, 21
b...Magnetic core, 22...Winding, 24...Guide pin, 25...Spring, 31...Resonance capacitor, 32...Inverting amplifier. Applicant's agent Patent attorney Takehiko Suzue

Claims (2)

[Claims] (1) In a cooker that automatically cooks food based on a cooking program, there is a weight detector that detects the weight of the food to be cooked as a change in inductance, and a means for determining the weight of the food to be cooked according to the output of this weight detector. and means for setting a cooking program according to the determination result. (2) A patent characterized in that the weight detector has an LC oscillation circuit consisting of inductance and capacitance that changes depending on the weight of the food to be cooked, and converts the change in inductance into a frequency and outputs it. A cooking appliance according to claim 1.