JPH05118554A - Weight sensor for cooking apparatus - Google Patents

Abstract

PURPOSE:To prevent a movable electrode plate from being left as it is deviated from its original position owing to a heavy load applied thereto with respect to a weight sensor for a cooking apparatus, which is adapted to detect the weight of a material to be cooked on the basis of the capacitance between a stationary electrode plate and the movable electrode plate. CONSTITUTION:A recessed part 35b is provided in a support frame 35, and a leg part 33b of a leaf spring 33 is disposed on the recessed part 35b, whereby the leg part 33b is so arranged as to slide along the recessed part 35b. When a material to be cooked 15 set on a turn table 40, a main part 33a of the leaf spring 33 is pressed and the leg part 33b is elastically deformed and slid, so that the main part 33a descends. When the material on the turn table 40 is removed therefrom, the leg part 33b moves slidingly, and the main part 33a returns to its original position.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a weight sensor for a cooker which detects the weight of an object to be cooked based on the electrostatic capacitance between a fixed electrode plate and a movable electrode plate.

[0002]

2. Description of the Related Art Conventionally, a microwave oven serving as a cooking device has
There is provided one in which a weight sensor detects the weight of an object to be cooked and the automatic cooking is performed based on the detection result. Hereinafter, a conventional configuration of the weight sensor of this type of cooker will be described with reference to FIGS.

First, in FIG. 5, a plurality of support plates 2 are attached to the bottom plate 1a of the heating and cooking chamber 1, and a frame 4 is screwed to the support plate 2 via a mounting plate 3. A printed wiring board 5, a leaf spring 6 as a movable electrode plate 6, a support frame 7 and an insulating spacer 8 are provided below the bottom surface of the frame 4.
Are fastened by screws 9.

As shown in FIG. 6, the leaf spring 6 has a rectangular main portion 6a and four L-shaped leg portions 6b integrally formed on the peripheral side portion of the main portion 6a. And a hole 6c into which the screw 9 is inserted at the tip of the leg 6b.
Are formed. A fixed electrode plate 10 is formed on the printed wiring board 5, and the fixed electrode plate 10 and the leaf spring 6 constitute a weight sensor 11.

By the way, holes 4a and 5a are formed in the frame 4 and the printed wiring board 5, respectively, and the gear portion 12 is inserted into these holes 4a and 5a. A convex portion 12a is provided at the tip of the gear portion 12, and the convex portion 12a is received and supported by the main portion 6a of the leaf spring 6.

A gear shaft 13 is inserted through the hole 1b in the bottom plate 1a of the cooking chamber 1 and the hole 3a in the mounting plate 3, and the lower end of the gear shaft 13 is attached to the upper part of the gear portion 12. The turntable 14 is attached to the upper end of the turntable 14. In this case, the gear part 12
Is connected to a drive motor via a gear mechanism (not shown), and when the drive motor rotates, the gear unit 12, the gear shaft 13, and the turntable 14 are rotated accordingly.

In this configuration, when the food to be cooked is placed on the turntable 14, the weight of the food to be cooked causes the turntable 14, the gear shaft 13, and the gear portion 12 to descend, so that the gear portion 12 has a convex shape. The portion 12a presses the main portion 6a of the leaf spring 6. Then, the leg portion 6b of the leaf spring 6 elastically deforms and the main portion 6a thereof descends, the distance between the fixed electrode plate 10 and the main portion 6a increases, and the electrostatic capacitance therebetween changes.

On the other hand, the microwave oven has a microcomputer (not shown) built therein. The microcomputer detects the capacitance as an oscillation frequency, converts the oscillation frequency into weight, and based on the measured weight. Then, the cooking time is calculated and the cooking is performed.

[0009]

However, since the leg portion 6b is conventionally attached by tightening the screw 9, the following problems occur.

That is, when a heavy object to be cooked is placed on the turntable 14, a large load acts on the main portion 6a of the leaf spring 6, and the leg portion 6b resists the fastening force of the screw 9. May be displaced laterally, and in this case, even when the food to be cooked is removed from the turntable 14, since the fastening force of the screw 9 still acts, the leg 6b is displaced. The main part 6a of the leaf spring 6 may not be returned to its original position because it is left standing.

FIG. 7 shows this experimentally. According to the figure, the value of the oscillating frequency when the food to be cooked is not placed on the turntable 14 (point α) is 2
8.25KHz, turntable 14
A food item having a weight of, for example, 4 Kg is placed on the (β
Point), the value of the oscillation frequency when this is removed (γ point) is 28.5 KHz, that is, the main portion 6a is deviated from the original position by an amount equivalent to 0.25 KHz.

Further, when cooking with high heat such as oven cooking, the support frame 7 is deformed due to high temperature, and the position of the legs 6b and the vertical position of the main part 6a are displaced from their original positions. And it may be left as it is.

If the position of the main portion 6a remains deviated in this way, the value of the oscillation frequency will deviate during the next automatic cooking, and the weight of the object to be cooked will be erroneously measured. The finished state of will deteriorate.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to prevent the movable electrode plate from being displaced due to a high load or a high heat, and always to be cooked. To provide a weight sensor for a cooking device capable of accurately detecting the weight of the cooker.

[0015]

The present invention has a fixed electrode plate and a movable electrode plate which is displaced under the load of the object to be cooked, and the object to be cooked is based on the capacitance between the two electrode plates. The present invention is directed to a weight sensor of a cooking device configured to detect weight, and is characterized in that the movable electrode plate is supported slidably in a direction substantially intersecting a displacement direction due to the load of the object to be cooked. Have.

[0016]

According to the above-mentioned means, when a load due to an object to be cooked is applied to the movable electrode plate, the movable electrode plate is pressed and displaced. After that, when the load is removed from the movable electrode plate,
Since the movable electrode plate is not subjected to the screw fastening force as in the conventional case, the movable electrode plate slides in the direction substantially intersecting the displacement direction and returns to the original position.

Further, even when the member supporting the movable electrode plate expands or contracts due to high heat, the movable electrode plate slides, so that its position does not remain displaced together with the member.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a microwave oven will be described below with reference to FIGS.

First, referring to FIG. 4, the microwave oven main body 21
A heating and cooking chamber 22 is provided inside, and a door 23 is pivotally supported on the front surface of the heating and cooking chamber 22.

A machine room (not shown) in which a magnetron, a fan device and the like (not shown) are arranged is provided on the side of the heating and cooking chamber 22. The microwave output from the magnetron is a waveguide. It is adapted to be supplied into the cooking chamber 22 through the. In addition, the microwave oven body 21
An operation panel 26 including various operation switches 24 and a display unit 25 is provided on the front surface of the machine room in FIG.

Although not shown, the microwave oven main body 21
Inside, a heater for oven cooking and a heater for grill cooking are provided, and the operator selects the operation switch 24 to perform range cooking or oven cooking. Alternatively, it is possible to select whether to perform grill cooking.

By the way, as shown in FIG. 1, a plurality of support plates 27 are welded to the bottom plate 22a of the heating and cooking chamber 22, and a frame 28 having a U-shaped cross section is attached to these support plates 27. It is screwed by a screw 30 via a mounting plate 29.

A printed wiring board 31 is disposed below the bottom surface of the frame 28, and the printed wiring board 3 is provided.
A fixed electrode plate 32 is formed on the lower surface of 1. Below the fixed electrode plate 32, the leaf spring 3 as a movable electrode plate is provided.
3, the printed wiring board 31 and the plate spring 33 are received and supported by the support frame 35, as will be described later. The fixed electrode plate 32 and the plate spring 33 constitute a weight sensor 34.

As shown in FIG. 2, the leaf spring 33 has a rectangular main portion 33a which faces the fixed electrode plate 32 and has a rectangular shape.
Three legs 33b integrally formed on the peripheral side of the main portion 33a
And a mounting portion 33c wider than the leg portion 33b, and a hole 33d is formed in the mounting portion 33c.

Also, four holes 35 are provided at the corners of the support frame 35.
a is formed, and the leg portion 33 of the leaf spring 33 is formed.
Three concave portions 35b for accommodating b are formed.

Below the support frame 35, two substantially U-shaped insulating spacers 36 are provided. The insulating spacer 36 is formed with a hole 36a corresponding to the hole 35a of the support frame 35 and a fitting recess 36b that fits on the outer surface of the recess 35b of the support frame 35. 36a, the hole 35a of the support frame 35, the hole 33d of the mounting portion 33c, and the hole 31 of the printed wiring board 31.
The insulating spacer 3 is inserted into the insulating spacer 3 and is screwed into a screw hole (not shown) formed in the corner of the frame 28.
6, support frame 35, leaf spring 33 and printed wiring board 31
Are attached to the bottom surface of the frame 28.

In this case, the leaf spring 33 has the mounting portion 33.
Only c is fixed, and the three leg portions 33b are arranged in the recess 35b of the support frame 35 closed by the printed wiring board 31, as shown in FIG. Therefore, the leaf spring 3
3, when the main portion 33a is pressed, the leg portion 33b and the attachment portion 33c are elastically deformed, and the leg portion 33b slides in the substantially left-right direction in the figure and is displaced downward.

In this case, the clearance dimension A between the lower surface of the printed wiring board 31 and the upper surface of the leg portion 33b is 0 <A ≦.
The depth dimension of the recess 35b is set so that the relationship is 50 μm.

By the way, holes 28a and 31b are formed in the frame 28 and the printed wiring board 31, respectively, and a gear portion 38 is inserted into these holes 28a and 31b. A convex portion 38a is provided at the tip of the gear portion 38, and the convex portion 38a is received and supported by the main portion 33a of the leaf spring 33.

Further, the bottom plate 22a and the mounting plate 29 of the heating and cooking chamber 22 are provided with holes 22b by burring, respectively.
And 29a are formed, and these holes 22b and 29a are formed.
A gear shaft 39 is inserted through the. The lower end of the gear shaft 39 is attached to the upper part of the gear portion 38.

The upper end of the gear shaft 39 projects into the cooking chamber 22, and a turntable 40 for placing an object to be cooked is attached to this portion. ..

In this case, the gear portion 38 is connected to a drive motor (not shown), and when the drive motor operates, the rotation of the gear portion 38 is transmitted through a gear mechanism (not shown).
The gear portion 38, the gear shaft 39, and the turntable 40 are rotated accordingly.

Next, the operation of the above configuration will be described.

When the food to be cooked is placed on the turntable 40 at the start of heating and cooking, the turntable 40, the gear shaft 39 and the gear portion 38 descend,
The main portion 33a of the leaf spring 33 is pressed by the convex portion 38a of the gear portion 38. Then, the leg portion 33b of the leaf spring 33 is
As the gear shaft 39 slides in a direction substantially intersecting with the descending direction, the leg portion 33b and the mounting portion 33c elastically deform, and the main portion 33a descends.

After that, when the operation switch 24 is selectively operated, a microcomputer (not shown) built in the microwave oven main body 1 changes the electrostatic capacitance between the fixed electrode plate 32 and the main portion 33a of the plate spring 33. It is detected as an oscillation frequency, and the weight of the object to be cooked and the cooking time thereof are calculated based on the oscillation frequency.

When a start key (not shown) is operated to start heating and cooking, the gear portion 38 is rotated via the drive motor, the gear shaft 39 and the turntable 40 are rotated, and together with that, the illustration is made. Cooking is started by the heating means.

After that, when the cooking is completed and the food to be cooked is removed from the turntable 40, the leg portions 33b and the attachment portions 33c of the leaf spring 33 elastically return, and the leg portions 33b are recessed 35b. Slide along the main part 33a
However, it returns to the original position where the cooked object is not placed on the turntable 40.

According to the above configuration, the following effects can be obtained.

That is, by disposing the leg portion 33b of the leaf spring 33 in the recess 35b of the support frame 35, the leaf spring 33
Slides in a direction (horizontal direction) substantially intersecting the displacement direction due to the load of the object to be cooked, so that the conventional screw fastening force does not act on the leaf spring 33.
Even if a heavy object to be cooked is placed on the turntable 40, if it is removed, the leaf spring 33 returns to its original position, so that the position of the leaf spring 33 is displaced due to the influence of the heavy object. It can be prevented from being left as it is, and the weight of the food can be always detected accurately.

Further, even if the support frame 35 is deformed by high heat, the leaf spring 33 slides, so that it is not displaced together with the support frame 35. Therefore, the position of the leaf spring 33 remains displaced due to the influence of high heat. It can be prevented that the weight of the food is always detected accurately.

In the above embodiment, only the mounting portion 33c of the leaf spring 33 is screwed and the three leg portions 33b are slid, but the mounting portion 33c is eliminated and used as the leg portion. All four legs may be slidable.

[0042]

As is apparent from the above description, according to the weight sensor of the cooker of the present invention, the movable electrode plate constituting the weight sensor is arranged in the direction substantially intersecting the displacement direction due to the load of the food to be cooked. Since it is supported slidably, it is possible to prevent the position of the movable electrode plate from being shifted due to heavy objects or the influence of high heat, and it is an excellent effect that the weight of the cooked object can always be detected accurately. Play.

[Brief description of drawings]

FIG. 1 is a vertical sectional front view showing an embodiment of the present invention.

FIG. 2 is an exploded perspective view of a main part

FIG. 3 is a vertical sectional side view showing an enlarged leg portion.

FIG. 4 is a perspective view of a microwave oven.

FIG. 5 is a vertical sectional front view taken along the E-line in FIG. 6 showing a conventional example.

FIG. 6 is a bottom view of a movable electrode plate portion.

FIG. 7 is a characteristic diagram showing the relationship between the load acting on the movable electrode plate and the oscillation frequency.

[Explanation of symbols]

31 is a fixed electrode plate, 33 is a leaf spring (movable electrode plate), 34
Is a weight sensor, 35 is a support frame, and 35b is a recess.

Claims (1)

[Claims] 1. A fixed electrode plate and a movable electrode plate that is displaced by receiving the load of an object to be cooked, and the weight of the object to be cooked is detected based on the electrostatic capacitance between the two electrode plates. The weight sensor for a cooker according to claim 1, wherein the movable electrode plate is supported so as to be slidable in a direction substantially intersecting a displacement direction due to the load of the object to be cooked.