JPH0763601A - Weight sensor - Google Patents

Abstract

(57) [Abstract] [Object] The present invention relates to a weight sensor used in a heating cooker such as a microwave oven, and provides a weight sensor having no impact load or maximum load applied to a weight detection unit. With the goal. A weight sensor according to the present invention includes a weighing dish 3 on which an object is placed, a load transmitting section 4 for supporting the weighing dish 3, a load lever 9 for supporting the load transmitting section 4, and a plate type lever. 9 has one end rotatably held and the other end having a leaf spring 11
It is configured to be supported by the weight detection unit 1 via the. With this configuration, it is possible to prevent impact load and overload from being applied to the weight detection unit 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a weight sensor used in a cooking device such as a microwave oven.

[0002]

2. Description of the Related Art In a conventional weight sensor of this type, as shown in FIG. 8, a circular plate for cooking serving as a weighing plate 3 installed in a cooking chamber 2 is cooked via a load transmitting section 4 The weight detection unit 1 supports the total weight of the object 5 and the circular plate for cooking. In such a configuration, the control unit 6 operates the magnetron 7 according to the weight of the food 5 detected by the weight detection unit 1. The radio wave radiated from the magnetron 7 was introduced into the cooking chamber 2 through the waveguide 8 to heat and cook the food 5.

[0003]

However, in the above-mentioned configuration, a large weight of a casserole or the like to be cooked is accidentally dropped on the cooking pan or the maximum weight detection unit 1 is allowed. When a load larger than the load is applied to the cooking pan, the weight detection unit 1 malfunctions or is damaged, which causes a problem that heating and cooking cannot be performed. In addition, depending on the model of the cooking device, when a weight sensor having a different maximum weight is required, there is a problem that a weight detection unit having a different maximum weight is required.

Further, when an electrostatic capacitance type weight detecting section is used as the weight detecting section, since the relationship between the load and the electrostatic capacity is non-linear, a calibration memory is required to detect an accurate weight. However, there are problems such as the need for a complicated circuit configuration such as, and the need for a complicated conversion formula.

The present invention solves the above-mentioned conventional problems or problems, and suppresses the impact load on the weight detection unit due to a drop load or the like, or a load more than the maximum allowable load is applied to the weight detection unit. An object of the present invention is to provide a weight sensor having a simple structure that does not occur. Another object is to provide a configuration that can easily realize weight sensors having different maximum weights by using the same weight detection unit.

Another object is to accurately detect the weight.

[0007]

In order to solve the above-mentioned problems, the weight sensor of the present invention comprises a weighing pan on which an object is placed, a load transmission part for supporting the weighing pan, and a plate-shaped lever for the load transmission part. While supporting one end of the plate-like lever rotatably and supporting the other end by a weight detection unit via a plate spring, it is possible to absorb an impact load and an overload.

When a capacitance type weight detecting unit having a diaphragm is used as the weight detecting unit, a fixed capacitance having a constant capacitance is connected in series.

[0009]

According to the present invention, when an impact load such as a drop load is applied to the cooking dish serving as a weighing dish, this impact load is transmitted to the weight detection unit through the plate-like lever and the plate spring. It Therefore, due to the cushioning action of the elastic body such as the leaf spring, a time delay occurs in the transmission of the impact load, and the impact load transmitted to the weight detection unit is suppressed.

Further, since the load is transmitted through the leaf spring, when an overload is applied, the leaf spring is bent and the load is prevented from being transmitted to the weight detection unit beyond a certain load. . Therefore, the weight detection unit is not damaged by the overload.

Further, since the ratio of the load transmitted to the weight detection unit can be adjusted depending on the position of the plate lever that supports the load transmission unit, the same weight detection unit can be used for maximum weighing. Different weight sensors can be easily configured.

Further, when a capacitance type weight detecting unit having a diaphragm is used as the weight detecting unit, a fixed capacitance having a constant capacitance value is connected in series, so that the combined capacitance value with respect to the load. Therefore, since it changes almost linearly, the linearity is improved and an accurate weight value can be easily obtained.

[0013]

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

(Embodiment 1) FIG. 1 is a sectional view of a main part of a weight sensor mounted on a heating cooker according to the present invention, in which the same components as those of the conventional example are designated by the same reference numerals. Reference numeral 9 is a plate-like lever that supports the weight transmission unit 4, 10 is a bottom plate that holds the weight detection unit 1, and 11 is a leaf spring that transmits the load transmitted to the plate-shaped lever 9 to the weight detector 1. Note that, in FIG. 1, the holding portion that holds the weight transmission portion 4 vertically is omitted. FIG. 2 is an enlarged partial cutaway perspective view of an essential part of FIG. 1, 9 shows a plate-like lever that supports the weight transmission part 4, one end 12 of which is rotatably held and the other end of which is a leaf spring. It is supported by the weight detection unit 1 via 11. Reference numeral 10 denotes a concave bottom plate that holds the weight detection unit 1. The concave bottom plate 10 is fixed to the bottom surface of the cooking chamber 2. One end 1 rotatably held
2 is held by V-shaped grooves 13 provided on both side surfaces of the bottom plate 10 so that the plate lever 9 does not move back and forth and left and right. Therefore, the plate lever 9 can freely rotate about the fixed end 12 as a rotation center. In addition, plate lever 9
Is made of a metal plate with a thickness of 1 mm and has a width (W) of 50 m.
m, and the total length (L) was 75 mm. In addition, the weight transmission unit 4
The position to support is 55 mm from the rotatable fixed end 12
(Lw). Therefore, if the load transmitted by the weight transmission unit 4 is Wt (kg), the load Ws transmitted to the weight detection unit 1 is represented by Ws = (Lw / L) × Wt.

Therefore, if the maximum load transmitted by the weight transmission unit 4 is 10 kg, the load transmitted to the weight detection unit 1 will be about 7.3 kg. As described above, the maximum load applied to the weight detection unit 1 changes depending on the position (Lw) that supports the weight transmission unit 4. Therefore, by appropriately selecting this distance, the same weight detection unit 1 is used and the maximum weighing Various different weight sensors can be easily realized.

FIG. 3 is a sectional view taken along the line AA 'in FIG. The leaf spring 11 has a width (Wb) of 20 mm and a length (Lb).
A 45 mm stainless steel spring having a plate thickness (Tb) of 0.5 mm was used. The load transmitted via the weight transmission portion 4 is transmitted to the leaf spring 11 through the fixing portion of the leaf spring 11 and is transmitted to the weight detection portion 1. At this time, when an overload exceeding the maximum load of the weight detection unit 1 is transmitted, the leaf spring 11 bends, and the tip 14 of the fixed portion contacts the bottom plate 10. Therefore,
By properly selecting the spring constant of the leaf spring 11, it is possible to prevent a load above a certain fixed load from being applied to the weight detection unit 1. Therefore, the weight detection unit 1 is not damaged.

Further, in the weight sensor of this construction, even if the plate-shaped lever 9 moves left and right, the weight transmission section 4 and the weight detection section 1
Since the relative positional relationship of is not changed, a weight error is unlikely to occur. FIG. 4 shows the results, where the horizontal axis represents the lateral displacement (ΔX) (mm) of the plate lever and the vertical axis represents the load (Wt) 1 k.
The error (ΔW) (g) when g is weighed is shown. If the lateral displacement of the plate lever 9 is within 1 mm, it indicates that the weight error is within 3 g. It should be noted that the lateral displacement within 1 mm can be easily realized with a simple configuration in which the plate levers 9 are installed in the V-shaped grooves 13 provided on both sides of the concave bottom plate 10.
When used in a cooking device such as a microwave oven, if the error is 10 g or less at a load of 1 kg, there is no practical problem.

(Embodiment 2) Next, a weight conversion method when a capacitance type weight detection unit having a diaphragm is used as the weight detection unit 1 will be described. FIG. 5 shows a cross-sectional view of a capacitance type weight detection unit having a diaphragm. Two upper and lower alumina substrates (plate thickness 0.6 mm) 15 and 16
It is fixed by a cylindrical sealing glass (height 50 μm, inner diameter 24 mm, outer diameter 28 mm) 17. Alumina substrate 15,
Circular electrodes (diameter 12 mm) 18 and 19 are formed on the inside of 16. A bullet-shaped load point 20 is fixed to the central portion of the upper substrate 15. When the load point 20 is pressed by the leaf spring 11, the upper substrate 15 is deformed and the electrostatic capacitance (Cw) formed between the electrode 18 and the electrode 19 changes. Figure 6
, The load (Wk) applied to the load point and the electrostatic capacitance (C
The relationship with w) is shown by the broken line 21. As can be seen in the figure, the relationship between the load and the capacitance has a large non-linearity and does not become a straight line. Therefore, a complicated circuit configuration is required to convert an accurate weight value from the electrostatic capacitance (Cw). Further, since the weight value cannot be easily converted, there are cases where a complicated conversion formula is used or a conversion table between the electrostatic capacity (Cw) and the weight value (Wk) is required. Further, the weight value was also inaccurate due to variations in capacitance value and error factors such as temperature characteristics and humidity characteristics. In FIG. 7, a broken line 22 indicates the result (Log (Cw)) shown in FIG. 6 when the horizontal axis represents the load (Wt) and the vertical axis represents the logarithmic value of the capacitance value.
Also in this case, the relationship with the weight value (Wt) is a non-linear relationship, which is significantly deviated from the linear relationship. Logarithmic conversion value (Log (Ca) of the combined capacitance value (Cap) when a fixed capacitance (Co) 30 pF is connected in series to the capacitance weight detector 1.
p)) is shown by the solid line 23. In the solid line 23, the weight value (W
The relationship with t) shows a linear relationship. Therefore, the weight value (Wt) can be easily calculated by using the logarithmic conversion value (Log (Cap)) of the combined capacity value. Therefore, the circuit configuration is simplified. Further, the weight value can be calculated by a simple conversion formula. Therefore, the converted weight value is also accurate. Further, even if there is a variation in the capacitance value, the linear relationship described above only moves in parallel, so the influence of an error on the converted weight value is reduced.
The capacitance value of the fixed capacitance can be set according to the capacitance value of the weight detection unit 1. In general, the capacitance value of the fixed capacitance may be within the change range of the capacitance value of the weight detection unit. That is, the range of the capacitance value (Co) of the fixed capacitance is Cmi, where Cmin is the lowest capacitance value of the variation range of the capacitance value of the weight detection unit 1 and Cmax is the highest capacitance value.
The range indicated by n <Co <Cmax is preferable.

The capacitance value (Co) of the fixed capacitance is the upper limit value C.
When the value exceeds max, the relationship between the weight value (Wk) and the logarithmic value of the combined capacity value deviates significantly from the linear relationship. Co = 60 in FIG.
The case of pF is shown by the dotted line 24. Further, when the capacitance value (Co) of the fixed capacitance becomes lower than the lower limit value Cmin, the weight value (W
The change in the combined capacitance value (Cap) with respect to the change in k) becomes small, and the detection sensitivity is significantly lowered. C in FIG.
The case of o = 10 pF is shown by a dotted line 25.

[0020]

As described above, according to the weight sensor of the present invention, the following effects can be obtained.

(1) Since the impact load applied to the cooking dish is suppressed and transmitted to the weight detection unit, the weight detection unit is not damaged or the weight sensor does not malfunction.

(2) Since a load applied to the cooking dish above a certain value is not transmitted to the weight detecting section, the weight detecting section will not be damaged or the weight sensor will not malfunction.

(3) By appropriately selecting the position of the weight transmission portion supported on the leaf spring, various weight sensors having different maximum weights can be easily realized by using the same weight detection portion.

(4) Since a fixed capacitance is connected in series to a capacitance type weight detection unit having a diaphragm, the weight value and the logarithmic value of the combined capacitance show a good linearity, so that complicated weight conversion is performed. The weight value can be detected easily and accurately without using.

[Brief description of drawings]

FIG. 1 is a configuration diagram in which a weight sensor according to an embodiment of the present invention is attached to a cooking device.

FIG. 2 is a partially cutaway perspective view showing an enlarged main part of the weight sensor.

3 is a sectional view taken along the line A-A 'in FIG.

FIG. 4 is a characteristic diagram of the weight sensor.

FIG. 5 is a cross-sectional view of a capacitance type weight detection unit having a diaphragm.

FIG. 6 is a load characteristic diagram of a capacitance type weight detection unit having a diaphragm.

FIG. 7 is a load characteristic diagram of a capacitance type weight detection unit having a diaphragm.

FIG. 8 is a sectional view of a cooking device using a conventional weight sensor.

[Explanation of symbols]

 1 Weight Detection Section 2 Cooking Room 3 Weighing Dish 4 Weight Transfer Section 5 Cooked Product 9 Plate Lever 11 Leaf Spring

Claims (4)

[Claims] 1. A weighing dish on which an object is placed, a load transmission section for supporting the weighing dish, a load lever for supporting the load transmission section, and one end of the plate-like lever being rotatably held, and A weight sensor in which the other end is supported by a weight detection unit via a leaf spring. 2. The weight sensor according to claim 1, wherein the same weight detection unit is used to configure weight sensors having different maximum weights by changing the relative positions of the plate-shaped lever and the load transmission unit. . 3. A weight detecting portion of the weight sensor is constituted by an electrostatic capacitance type having a diaphragm, and a combined capacitance with a fixed capacitance connected in series to the electrostatic capacitance type weight detecting portion is detected, and the combined capacitance is detected. A weight sensor that detects the weight from the. 4. The capacitance value of the fixed capacitance connected in series is within a range in which the minimum capacitance value of the capacitance type weight detection unit is the lower limit and the maximum capacitance value is the upper limit. Weight sensor.