JPS62124421A - Weight detector - Google Patents

Abstract

PURPOSE:To measure accurate weight by performing load to a pressure sensitive sensor via a pressurized point and maintaining a pressurized area and a pressurized position constant. CONSTITUTION:The load of an object to be measured is transmitted from a shaft 8 to load receiving metal fittings 7 and weighed on the pressurized point 5 via a plate spring 6 for protection. The pressurized point 5 is weighed on a flat plate 2 of the upside of the pressure sensitive sensor 1 and the flat plate 2 of the upside is deformed and an interval between the upper and lower electrodes 3 is changed. This can be detected as a change of the electrostatic capacity. Here, the pressurized surface of the pressurized point 5 is made a plane of the fixed area and the pressurized position is determined by a sensor cover 10. In this way, since the pressurized area and the pressurized position are made fixed, the accurate weight can be measured.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a scale for measuring the weight of objects.

In addition, the present invention relates to a weight detection device as a means for detecting the weight of an object and effectively utilizing the weight information to improve a function or performance. For example, there is a cooking device that effectively utilizes weight information, which can improve cooking performance by detecting the weight of food in a heating chamber and heating it at the optimal output. The present invention relates to such a weight detection device.

2. Description of the Related Art In a conventional scale, for example, shown in FIG. 7, an object to be measured is placed on a dish 18, and the load is connected to a parallel movement side parallel holding spacer 29 by a load support fitting 31.

Further, the parallel movement side parallel holding spacer 29 is connected to the fixed side parallel holding spacer 30 via a plate spring 28 which is fixed vertically in a parallel state. The fixed side parallel holding spacer 30 is fixed to a base 34 via a support fitting 32. The two sheet metal electrodes 33 are attached to the parallel movement side parallel holding spacer 29 and the stationary side parallel holding spacer 30, respectively.

When the object to be measured is placed on the plate 18, the load causes the leaf spring 2 to
8 is deformed, and the portion attached to the parallel movement parallel holding spacer 29 side is displaced downward. As a result, the distance between the two sheet metal electrodes changes, and the capacitance between the sheet metal electrodes changes.

The weight is measured by detecting this change in capacitance.

Problems to be Solved by the Invention However, in such weight detection devices for scales and cooking appliances, the following problems arise because the weight is detected by the capacitance between the sheet metal electrodes.

First, there is air between the sheet metal electrodes, and the conductivity of the air changes depending on the humidity at that time. As a result, the capacitance between the sheet metal electrodes changes, making it impossible to accurately detect weight. Further, since a heating cooker or the like is installed in a kitchen or generates water vapor from food, etc., the humidity changes greatly, making accurate weight detection difficult.

The second problem is that dust or the like adheres to the sheet metal electrodes, and when the dust becomes moist, the capacitance between the sheet metal electrodes changes, making accurate measurement impossible.

The other is that the sheet metal electrode has an area of about 501XX50MM to 100X100M, and the electrode spacing is 5 to 1
It has 0 wings and is large. This is because the change in electrode spacing due to load is about 2 to 3 mi+, and in order to detect this as a change in capacitance, it is necessary to increase the area of the electrodes.

Since the area is large and the amount of displacement between the electrodes is large, it is difficult to find a way to isolate the space between the electrodes from the outside and eliminate the influence of humidity. As described above, in the conventional method, it is difficult to deal with humidity, lumps, etc., so there is a problem in that accurate weight detection is extremely difficult.

The present invention solves these conventional problems, and aims to eliminate the influence of humidity and dust on measurement accuracy and realize accurate weight measurement.

In order to achieve the second objective of ``Means for Solving the Problems'', the weight detection device of the present invention has a small load detection section and a pressure-sensitive sensor with small displacement due to load, and is designed to prevent external humidity and dust. The aim is to accurately detect weight without being affected by such factors. The pressure-sensitive portion of the pressure-sensitive sensor has a predetermined size and is configured to pressurize a predetermined position of the pressure-sensitive sensor. For this purpose, a pressure point is provided, and a predetermined position of the pressure sensor is pressurized via this pressure point.

By applying pressure to a predetermined amount at a predetermined position 1a of the pressure-sensitive sensor, accurate weight detection becomes possible. Generally, pressure sensitive sensors have different characteristics for weight detection depending on the pressure applied.

Furthermore, the characteristics for weight detection differ depending on the size, especially the area, of the pressurizing section. Therefore, by keeping the pressurizing position and the size of the pressurizing part constant, it is possible to obtain stable weight detection characteristics.

EXAMPLE Hereinafter, an example of the present invention will be described based on the drawings.

As shown in FIG. 2, the configuration of the pressure-sensitive sensor 1 is such that electrodes 3 are printed on two flat plates 2 that are insulating and elastic, and the flat plates 2 are bonded together with a spacer 4 interposed therebetween. .

The flat plate 2 may be made of an insulating and elastic material such as ceramic.

Also, the size of the conventional sheet metal electrode is 50 mw + × 5
Q mx ~ 100 + uXI QC) rx and electrode spacing is also 5
It was a large one, about 101 meters long. However, in the present invention, the flat plate 2 is 30 II × 3 Q mm, the electrode spacing is 50 to 60 μm, and the thickness of the flat plate 2 is 0.5 nm.
, the thickness of the pressure sensor 1 is 1.2 to 1.3 m.
jI can be made very small. Furthermore, the capacitance as an electrical characteristic and its rate of change with respect to load can be obtained as in the conventional case.

The reason is that the electrode spacing between the two flat plates 2 is set to 50 to 60 μm.
This is because they are bonded together at narrow intervals, and can be easily realized on a par with the current technique of bonding glass such as liquid crystals used as display elements. Therefore, since the electrode spacing is small, the electrode area can be reduced in order to obtain the same capacitance as in the conventional case. Further, when the flat plate 2 is made of alumina ceramic having a thickness of 5 to 5, the displacement is 10 μm for a load per gram, which is very small. However, even if the displacement due to the load is small, the electrode spacing is small, so the rate of change in capacitance is large and is equal to or higher than that of the conventional method.

As described above, the pressure-sensitive sensor 1 replaces the functions comparable to those of the conventional leaf spring 28 and sheet metal electrode 33, is more compact, and can easily isolate the electrode gap from the outside.
It is not affected by humidity changes or dust.

FIG. 1 shows an embodiment of a load transmission mechanism to a pressure-sensitive sensor 1. As shown in FIG. The load of the treasure 111 is transmitted from the shaft 8 to the load receiver 7, and is applied to the pressure point 5 via the protective leaf spring 6. The protective leaf spring 6 is provided to soften the impact. The pressure point 5 is applied to the upper flat plate 2 of the pressure-sensitive sensor 1, and the upper flat plate 2 is deformed to change the interval between the upper and lower electrodes 30.

This can be detected as a change in capacitance.

The deformation of the upper flat plate 2 of the pressure sensor 1 in response to the load varies depending on the size of the pressure point 5, that is, the area on which the flat plate 2 is pressed, and the weight detection characteristics change. The smaller the pressurized area, the larger the deformation, and the larger the pressurized area, the smaller the deformation.

Furthermore, the deformation characteristics of the flat plate 2 differ depending on the position where the flat plate 2 is pressed. When pressure is applied to the same area, the deformation is greatest at the center and decreases as you move away from the center.

Therefore, by keeping the pressurized area and pressurized position constant, accurate weight measurement becomes possible. Therefore, the pressurizing surface of the pressurizing point 5 is a flat surface of a constant plane, and the pressurizing position is determined by the sensor cover 10.

Furthermore, the shape of the portion of the pressurizing point 5 that comes into contact with the protective leaf spring 6 is hemispherical. The reason why the surface is made spherical is that the force received from the protective leaf spring 6 can be received at the center of the pressure point 5, and the pressure surface of the pressure point 5 presses the flat plate 2 evenly.

Therefore, even if the object to be measured is placed at a position deviated from the shaft 8 and the protective leaf spring 6 is tilted, it will be received at approximately the center of the pressurizing point 5, and the pressurization on the flat plate 2 will be approximately uniform. The shape of this pressurizing point 5 does not have to be spherical. In other words, the same effect can be obtained by making the area receiving the load sufficiently smaller than the pressurizing surface.

FIG. 3 is a partially sectional perspective view showing a support mechanism that supports the load of the object to be measured and transmits the load to the pressure sensor 1 as shown in FIG.

In actual weight measurement, it is impossible to place the plate in the center of the plate 18.Therefore, it is necessary to accurately concentrate and transmit the load to the pressure sensor 1 regardless of the placement position. There is a donkey pal mechanism that is commonly used in scales and the like.

The advantages of this are that accurate weight can be detected regardless of the mounting position, and that the mounting table can be displaced while maintaining a parallel state.

The structure of the donkey pal mechanism is such that the four corners of a parallelogram are movable, the - side is fixed, and the opposite side is movable in parallel. In FIG. 3, the parallel movable metal fitting 11 is a parallel movable side, and the fixed support metal fitting 12 on the opposite side is a fixed side. Then, hold the two parallel holding metal fittings 13 with pins 1 at both sides and the four corners.
4 to form a parallelogram. Then, the shaft 8 is attached to the parallel motion fitting 11, and the load is applied to the pressure sensor 1.
The structure shall be configured to transmit information to

By using the donkey pal mechanism in this way, loading
The weight can be concentrated on the small pressure-sensitive sensor 1 regardless of its position, making it possible to accurately measure weight.

FIG. 4 is a side sectional view showing a case where the weight detecting device of the present invention is mounted on a heating cooker. This type of device is attached to the parallel motion fitting 11 to detect the weight of the food 19 and control the output of the magnetron 22 accordingly, so that the weight can be accurately measured without being affected by humidity or dust. Cooking performance also improves. Furthermore, there is no need to place the food in the center of the plate 18, making it possible to realize an easy-to-use cooking device.

FIG. 5 shows an oscillation circuit that converts a change in capacitance of the pressure-sensitive sensor 1 into an oscillation frequency, and is a circuit that converts a change in weight into a change in frequency. This circuit is the same as the conventional one for detecting a change in capacitance of the sheet metal electrode 28.

FIG. 6 is a circuit diagram showing an output control configuration of the cooking device shown in FIG. 4. A change in capacitance of the pressure sensor 1 is converted into a change in frequency by an oscillation circuit 23, which is counted by a microcomputer 24 and a weight corresponding to the frequency is calculated. The microcomputer 24 stores the correlation between frequency and weight. Then, a signal for controlling the output of the magnetron gain 2, etc. in accordance with the weight is output to the drive circuit 25. The signal of the drive circuit 25 is the magnetron output control relay 26 and the heater output control relay 27.
to drive.

As described above, according to this embodiment, stable load transmission to the pressure sensor 1 can be realized, and accurate weight detection can be achieved.

Effects of the Invention As described above, the weight detection device of the present invention provides the following effects.

(1) Stable load transmission to the planar pressure-sensitive sensor is possible, allowing accurate weight detection.

(2) By making the upper side of the pressure point smaller than the spherical surface or pressure surface, the weight of the shaft or load receiver can be accurately detected even if the metal fittings are tilted.

[Brief explanation of drawings]

Fig. 1 is a partial sectional view showing the load transmission state of a pressure-sensitive sensor according to an embodiment of the present invention, Fig. 2 is an exploded perspective view of the pressure-sensitive sensor, and Fig. 3 shows the pressure-sensitive sensor and the load support mechanism. Fig. 4 is a side sectional view of a heating cooker equipped with the pressure-sensitive sensor, Fig. 5 is a circuit diagram showing an oscillation circuit to which the pressure-sensitive sensor is connected, and Fig. 6 is a partial sectional perspective view showing the pressure-sensitive sensor. FIG. 7 is a side view showing the structure of a conventional scale. 1... pressure sensitive sensor, 2... flat plate, 3...
... Electrode, 4 ... Spacer, 5 ...
...Pressure point, 6...Protective leaf spring, 7.
...Load receiver is metal fitting, 8...Shaft, 9
...Sensor support fitting, 10...Sensor cover, 11...Parallel movement fitting, 12...
・Fixing support bracket, 13... Parallel holding bracket, 1
4...pin, 15...motor, 16...
...Gear, 17...Turntable, 1
8...Plate, 19...Food, 20...
... Heating chamber, 21 ... Door, 22 ...
・Magnetron, 23...Oscillation circuit, 24...
... Microcomputer, 25 ... Drive circuit, 26 ... Magnetron output control relay, 27 ... Heater output control relay, 28 ...
...Plate spring, 29...Parallel movement side parallel holding spacer, 30...Fixed side parallel holding spacer,
31...Load supporting metal fittings, 32...Supporting metal fittings, 33...Sheet metal electrodes, 34...Foundation. /-11 Mushi 5 Rin Senbu 4-1-Sveg N Ward - Figure 4 Figure 5 Figure 7 Noboru

Claims (4)

[Claims] (1) A pressure-sensitive sensor that converts applied force into an electrical signal, a weight detection circuit that detects the weight from the electrical signal from the pressure-sensitive sensor, and a weight detection circuit that supports the load of the object to be measured and transfers the load to the pressure-sensitive sensor. a support mechanism for transmitting pressure to the pressure sensor, and a pressure point having a pressure area smaller than an area capable of sensing pressure of the pressure sensor is interposed between the support mechanism and the pressure sensor. (2) The pressure-sensitive sensor is made up of two flat plates made of elastic insulators, a spacer that attaches the flat plates parallel to each other at regular intervals, and electrodes provided on each opposing surface of the two flat plates. Claim 1, which is configured to convert the force during pressurization into an electrical signal as a change in capacitance as the distance between the electrodes changes due to the bending deformation of the flat plate.
The weight detection device described in section. (3) The weight detection device according to claim 1, wherein the area of the pressure point in contact with the pressure sensor is larger than the area facing the support mechanism. (4) The weight detection device according to claim 1, wherein the pressure point facing the support mechanism has a spherical shape.