JPS63197817A - High-frequency heating apparatus - Google Patents

Abstract

PURPOSE:To prevent radio waves from leaking to a weight sensor by driving upward a shaft part connecting a table on which a material to be heated is placed to the weight sensor during the high frequency wave oscillation, and hermetically coupling a bearing end surface to a shaft penetrating part thereby to block a gap therebetween, in an electronic range provided with a weight sensor. CONSTITUTION:When a cooking start switch of an operating part 25 is manipu lated, a gap X between sensor plates 11a and 11b of a weight sensor 5 increases due to the weight of a food 3, and the static capacitance of sensor plates 11a and 11b varies and the variation appears as a variation of an oscillation fre quency. The frequency is detected by a control circuit 23 to recognize the weight. After the passage of time required for the weight detection, a motor 22 operates, and rotates an eccentric cam 21 so that its position becomes highest, thus pushing up a slide plate 20. As a result, the end surface of a bearing 9a tightly adheres to the opening edge of a penetrating hole 7a to block the gap with a depressed cover 7. By this constitution, the leakage of radio waves to the side of the weight sensor can be prevented.

Description

[Detailed Description of the Invention] [Objective of the Invention] (Industrial Application Field) This invention detects the weight of the object to be heated with a mold opening sensor, controls the heating time, etc. according to the detected weight, and The present invention relates to a high-frequency heating device that optimally heats an object to be heated on its own.

(Prior art) In recent years, microwave ovens (high-frequency heating devices) have improved operability by measuring the weight of the food being cooked and automatically setting the optimal heating time according to the weight. It is being commercialized.

Conventionally, in such a microwave oven, as shown in FIG. In addition to disposing a t1 amount sensor 5 on the lower side of the bottom wall 1a, a shaft 6 (corresponding to the shaft portion that also serves as a rotation shaft for rotating the rotary plate 4) passing through the bottom wall 1a is provided. ), and a structure is used in which the rotating plate 2 is supported movably in the vertical direction.

Specifically, on the lower surface of the bottom wall 1a, together with the cover 7, a vertically displaceable donkey pal 414!8 (spring all) composed of leaf springs 8a and 8b is installed. Upper and lower rotary bearings 9a and 9b are installed on the extending end side of this donkey pallet tji 18 to rotatably support the lower part of the shaft 6, and a turntable motor for rotating the shaft 6 is installed. Install 10. Roughly, directly below the motor 10, there are two opposing sensor plates 11a (movable side) and 11b (upper and lower) whose gap X changes according to the vertical movement of the shaft 6.
The structure has a fixed side).

More specifically, the sensor plate 11b is provided on the frame 12 attached to the bottom wall 1a, and the sensor plate 11a is attached to a fulcrum 13 formed on the donkey pal mechanism 8 side of the frame 12.
It is connected to a leaf spring 15 (consisting of a projection) laminated together with an elastic member 14 thereon. And these sensor plates 11a
, 11b is an oscillation circuit 16 (attached to the weight sensor 5) made of a PC board (printed circuit board) on which electronic components are mounted.
The weight is detected from the change in capacitance between the sensor plates 11a and 11b.

That is, when a load is applied to the shaft 6, the reinforcing plate 17 provided at the extending end of the donkey pal mechanism 8 descends together with the shaft 6, pressing the force point side of the leaf spring 15, and thereby pushing the sensor plate 118 towards the fulcrum 13. and move upwards as the center.

(Problem to be Solved by the Invention) However, the structure of detecting the weight of the food 3 using the upward motion of the shaft 6 requires a gap between the through hole 7a of the cover 7 and the shaft 6. (because the axis 6 is not affected by rfJilj force, etc.). Moreover, the gap A between the upper bearing 9a and the cover 7 directly above it not only fluctuates more and more as heavier objects are placed on the rotary plate 4, but it also has a 0.00-degree gap in order to accurately detect the weight even when there is no load. 3~0.5s+J
A certain amount of clearance must be determined.

Therefore, during high frequency (microwave) oscillation, the radio waves
There is a risk that the liquid may leak from the gap A along the periphery of the weight sensor 5 to the weight sensor 5 side.

Such radio wave leakage adversely affects the oscillation circuit 16, causing it to malfunction, or in severe cases, destroying the PC board that constitutes the oscillation circuit 16. Moreover, there are cases where it leaks to the outside of the microwave oven.

The present invention has been made in view of these problems, and its purpose is to provide a high-frequency heating device that can prevent leakage of radio waves to the weight sensor side.

[Structure of the Invention (Means and Effects for Solving Problems) This invention provides a gap closing means 20.21 that drives the shaft portion 6 upward to bring the bearing end face into close contact with the shaft penetrating portion 7a directly above the bearing. In addition to providing the gap A, a control section 23 that operates the gap closing means 20, 21, and 22 during high frequency oscillation is provided to eliminate the gap A during high frequency oscillation, thereby cutting off radio wave leakage.

(Example) The present invention will be described below based on an example shown in FIGS. 1 and 2. In addition, in the drawings, parts that are the same as those described in the "Prior Art" section are given the same reference numerals and their explanations are omitted, and in this section, different parts, that is, the main parts of the invention, will be explained. Make it.

In other words, 20 is a slide plate protruding from the right side of the motor mounting plate (or reinforcing plate 17, etc.) on the extending side of the donkey pal mechanism 8, and 21 is the donkey pal mechanism directly below the slide plate 20. This is an eccentric cam provided in the inner part of the slide plate 8 in parallel with the slide plate 20. Eccentric cam 21
, there is a through hole 7a directly above the end surface of the upper bearing 9a.
A cam is used in which the maximum cam height is determined by the gap A to the open end of the cam. The cam center 2 of this eccentric cam 21
For example, the output shaft of a lifting motor 22 is connected to 1a, and the rotation of the eccentric cam 21 pushes up the slide plate 20, pushing up the shaft 6 together with the bearings 9a, 9b and the motor 10, so that the end face of the bearing 9a is inserted into the through hole. It is arranged so that it can be brought into close contact with the periphery of the opening (corresponding to the shaft penetrating portion) of 7a. In other words, the gap around the shaft 6 can be closed.

Further, the motor 22 is connected to a control circuit 23 (comprised of a microcomputer and corresponding to a control section).

Then, in response to the cooking start operation on the operation unit 24 connected to the control circuit 23, high-frequency oscillation is stopped for several seconds after the start of cooking, and the time for measuring the weight of the food 3 is set. After measuring the weight, the motor 22 is energized to bring the bearing end face into close contact with the opening periphery of the through hole 7. In other words, by controlling the eccentric cam 21, during high frequency oscillation,
The structure is such that a gap communicating between the inside and outside of the heating chamber 1 can be blocked.

However, the microwave oven equipped with such a weight sensor 5 is
After placing the food 3 on the rotary plate 4 set on the placing plate 2, the door (not shown) is closed and the cooking start switch (not shown) of the operation unit 25 is operated. Then, within a few seconds after the cooking start switch is operated, the weight of the food 3 is detected by the weight sensor 5, as in the conventional case.

Specifically, as shown in FIG. 1, the shaft 6 is lowered substantially vertically by the donkey pallet structure 8. Then, the force point of the leaf spring 15 is pressed by the reinforcing plate 17, which lowers at the same time as the shaft 6, and the force point side of the sensor plate 11a is moved upward about the fulcrum 13, thereby increasing the gap X. As a result, the capacitance between the sensor plates 11a and 11b changes, and the oscillation frequency of the oscillation circuit 16 changes.

Then, this frequency is detected by the control circuit 23, and the food 3
It recognizes the weight as the weight, and automatically sets the optimal heating time according to that weight. Note that high frequency waves are not oscillated during this weight measurement step.

Then, once the time for these weight measurements has elapsed,
The motor 22 is energized as expected, and the eccentric cam 21 is rotated so that the highest part of the cam is at the top, and the slide plate 20 is pushed up.

Here, since the eccentric cam 21 has a cam height corresponding to the dimension between the shaft end of the bearing 9a and the opening end of the through hole 7a, by pushing up the slide plate 20, as shown in FIG. The end face of the bearing 9a is brought into close contact with the opening periphery of the through hole 7a. In other words, the gap around the through hole 7a is closed, and the concave cover 7 cuts off the path that causes radio waves to leak from inside the refrigerator.

Then, after such a state in which radio wave leakage is blocked is established, the magnetron (not shown) is activated and the motor 10 is activated. As a result, the rotating food 3 is irradiated with high frequency waves oscillated by the magnetron, and the food is heated and cooked.

During such cooking (during high-frequency oscillation), the radio wave leakage blocking state continues between the inside and outside of the heating chamber 1, so the radio waves inside the refrigerator will no longer leak to the weight sensor 5 side. .

Therefore, the oscillation circuit 16 may malfunction due to the high frequency inside the refrigerator, or even worse. The control circuit 23 attached to the motor 10 and the microwave oven operation panel (not shown) will not be destroyed (which is caused by high frequency waves leaking along the connection lead wires), ensuring safety and high opening. This means that good cooking can be done based on weight measurement. Of course, it also prevents radio waves from leaking to the outside of the microwave oven.

In one embodiment, the through hole 7a of the cover 7 attached to the lower surface of the bottom wall 1a of the heating chamber 1 is closed to block radio wave leakage, but in a structure without the cover 7, the bottom wall 1a
The end face of the bearing 9a may be brought into close contact with the through hole 1b to close it. In short, it is sufficient as long as the bearing end surface is brought into close contact with the portion that will become the shaft penetrating portion directly above the bearing 9a.

Further, in one embodiment, the eccentric cam 21 and the motor 22 are used to drive the bearing 9b upward.
Other structures may also be used.

[Effect of the invention] As explained above, according to the present invention, during high frequency oscillation,
There will be no gap around the shaft that would allow communication between the inside and outside of the heating chamber. In other words, the path leading to radio wave leakage is cut off.

Therefore, it is possible to prevent radio wave leakage to the weight sensor side.
Heating can be performed using highly accurate double positive detection without malfunction or destruction of electronic components.

[Brief explanation of the drawing]

FIG. 1 and FIG. 2 show one embodiment of the present invention.
The figure is a cross-sectional view showing the main part of the radio wave leakage prevention structure together with the state in which the weight is detected. Figure 2 shows the state in which the end face of the bearing is brought into close contact with the opening periphery of the through hole of the cover to prevent radio wave leakage. 3 is a sectional view showing a high frequency heating device equipped with a conventional weight sensor. 1... Heating chamber, 2... Rotating plate (mounting part), 3...
Food (heated object), 5... Weight sensor, 6... Shaft (
Shaft part), 7a... Through hole (shaft penetrating part), 9a... Bearing, 20.21.22... Slide plate, eccentric cam, motor (gap closing means), 23... Control circuit ( control part)
. Applicant's agent Patent attorney Takehiko Suzue Figure 1 Figure 2

Claims (1)

[Claims] A mounting part for placing the object to be heated is disposed on the upper side of the bottom wall of the heating chamber so as to be movable in the vertical direction, while a weight sensor is provided on the lower side of the bottom wall, and these are connected to a shaft that passes through the bottom wall. In a high-frequency heating device, the lower part of the bottom wall of the shaft is supported by a bearing that moves in the vertical direction together with the shaft,
The present invention is characterized by providing a gap closing means for driving the shaft portion upward to bring the bearing end face into close contact with the shaft penetrating portion directly above the bearing, and further comprising a control portion for operating the gap closing means during high frequency oscillation. High frequency heating device.