JP2004226383A - Capacity type load detecting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a capacity type load detecting device in which a load detecting part is efficiently arranged. <P>SOLUTION: The device has an upper plate 1 on which a load is placed, a lower plate 2 which holds a load detecting part, load detecting springs 3a, 3b, 3c and 3d which hold the upper plate 1 and are displaced depending on the weight of the placed load, and three intermediate plates 41, 42 and 43 which are arranged between the upper and lower plates 1 and 2 and polarize the space between the plates into a plurality of spaces. The device is configured to be polarized into four poles. Intermediate springs 51, 52, 53 and 54 for evenly dividing the space distance are arranged between the polarized plates, i.e., the polarized upper and lower plates 1 and 2 and intermediate plates 41, 42 and 43. A capacity part for detecting the load weight is constituted of spaces between respective adjacent plates of the upper plate 1, plural intermediate plates and lower plate 2, and a load detecting spring 3 is displaced depending on the load weight applied to the upper plate 1. This displacement amount is fractionated into displacement amounts between the plural polar plates (1, 51, 52, 53, 54, 2), which are detected as a lager amount of changes in capacity values between the respective polar plates. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a capacitive load detecting device, and more particularly to a capacitive load detecting device having a plurality of pole plates between upper and lower loading plates.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a capacitive load detection device is generally configured as a device / apparatus for detecting the magnitude of a load. As well-known objects, for example, a method of mechanically measuring the displacement of a spring formed in a cylindrical shape, a load cell method using a strain generating section and a resistance wire type strain gauge, and detecting the displacement as a capacitance. A method of detecting a voltage change amount by a bridge circuit is known.
[0003]
[Patent Document 1]
Japanese Patent Application Laid-Open No. 2000-199723 (Patent No. 3273768)
"Load measurement device and load measurement method"
[0004]
FIG. 4 shows a configuration example of a conventional capacitive load detection device, and is a side view showing a basic configuration example of Patent Document 1 described above. The above-mentioned prior invention example 1 which is similar to the present invention in the technical field is an invention which is the same inventor as the present invention. In Patent Document 1, the electrode plate 20 is configured to have the electrode plate 20 between the upper and lower loading plates 10 and 30, and each of the electrode plates 10, 20 and 30 receives a similarly-loaded load, and Springs 61 and 62 are provided between each of the electrodes 20 and 30, and the capacitor formed between the opposing electrode plates has a multilayer capacitor structure. Therefore, each of the springs 61 and 62 between the respective electrode plates receives a load that is substantially equally loaded.
[0005]
[Problems to be solved by the invention]
However, according to the configuration of the load detection device of the invention of the prior application, since the springs between the respective electrode plates receive the loaded load, all the springs need to have a load capacity corresponding to the applied load. Therefore, all of the individual springs are mechanically large, the overall device height is increased, and it is difficult to reduce the spacing between the plates.
[0006]
As the distance between the plates increases, the capacitance formed thereby decreases. When the absolute capacitance value is small, the change amount of the capacitance value detected by the interval displacement amount is also small accompanyingly. As a result, the detected capacitance value displaced according to the load becomes small, and it becomes difficult to detect the load with high accuracy.
[0007]
Further, the height dimension of the load detection device becomes large, and it becomes difficult to reduce the thickness, size, weight, and the like. In addition, the position of the load receiving surface with respect to the bottom surface receiving the load increases, and accordingly, the position of the center of gravity of the load increases, and the stability of the applied load decreases. This decrease in stability results in a decrease in measurement accuracy.
[0008]
The need for structurally higher strength leads to the need for mechanical strength, and generally involves problems that increase costs, such as material costs, processing costs, and assembly adjustment costs.
[0009]
The invention of the present application is related to the basic principle of the above-mentioned prior invention, and furthermore, a capacity type capable of efficiently configuring a load detection unit and improving performance such as improvement of measurement accuracy, simplification of configuration, reduction in thickness and weight, and the like. An object is to obtain a load detection device.
[0010]
[Means for Solving the Problems]
In order to achieve this object, the capacitive load detection device of the present invention includes an upper plate to which a load to be measured is applied and which is movable according to the magnitude of the load amount, and a lower plate which holds the upper plate. A load detecting spring disposed between the upper plate and the lower plate to change a distance between the upper plate and the lower plate according to the magnitude of the load, and housed in a space formed by the upper plate and the lower plate. And an intermediate plate that divides the interval into at least two layers, and is formed between any of the upper plate, the intermediate plate, and the lower plate. The amount of applied load is detected based on the amount of change in capacitance based on the change in the interval distance.
[0011]
Further, at least one intermediate spring is further provided between each of the upper plate and the intermediate plate and the intermediate plate and the lower plate. The upper plate and the lower plate have one pole, and the intermediate plate has the other pole. And a oscillating circuit for connecting a capacitor formed of two layers of space portions in parallel, enabling a load to be detected based on a change in the capacitance, and changing an oscillation frequency in accordance with a change in the size of the capacitor. It is preferable that the load amount can be measured corresponding to the oscillation frequency based on the change amount of the capacitance based on the space.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, an embodiment of a capacitive load detecting device according to the present invention will be described in detail with reference to the accompanying drawings. Referring to FIGS. 1, 2 and 3, there is shown an embodiment of the capacitive load detecting device of the present invention. FIG. 1 is a plan view from above with the upper plate removed. FIG. 2 is a side view corresponding to FIG. FIG. 3 is a conceptual diagram showing an example of connection between electrode plates.
[0013]
The capacitive load detection device according to the present embodiment includes an upper plate 1 on which a load is loaded, a lower plate 2 holding a load detection unit, and a load displaced in accordance with the amount of load loaded while holding the upper plate 1. It has detection springs 3a, 3b, 3c, and 3d, and three intermediate plates 41, 42, and 43 that are disposed between the upper plate 1 and the lower plate 2 and that polarize the interval between the two plates into a plurality of spaces. Be composed. Accordingly, the space between the upper plate 1 and the lower plate 2 is configured to be polarized to four poles by the three intermediate plates 41, 42, and 43.
[0014]
Between the upper plate 1 and the lower plate 2, the distance between the plurality of poles of the intermediate plates 41, 42, 43 is evenly set between the upper plate 1 and the lower plate 2 according to the change in the distance between them. Intermediate springs 51, 52, 53, 54 for changing are provided between the respective intermediate plates 41, 42, 43, and between the upper plate 1 and the intermediate plate 41 and between the lower plate 2 and the intermediate plate 53. In addition, four intermediate springs 51, 52, 53, and 54 (for example, 51a, 51b, 51c, and 51d) are arranged as one set between the intermediate plates. Therefore, the total number of intermediate springs used in this embodiment is (4 / one pole) × 4 = 16.
[0015]
In this embodiment, the load detecting springs 3a, 3b, 3c, and 3d and the intermediate springs 51, 52, 53, and 54 are configured to expand and contract according to the natural length at the time of no load and the length at the time of rated load. In order to increase the ratio, a conical spring having a trapezoidal side shape is used. By using this conical spring, the height of the spring at the time of rated load can be further reduced. Therefore, the distance between adjacent electrode plates can be made smaller, and as a result, the amount of change in the detected capacitance value from when no load is applied to when a load is applied can be made larger.
[0016]
A capacity unit for detecting a load amount is formed between each of the adjacent upper and lower plates 1, 2 and 3. The load detection spring is displaced in accordance with the amount of load applied to the upper plate serving as the loading plate. This displacement amount is subdivided into a displacement amount between a plurality of electrode plates by an intermediate spring, and is formed as a change amount of a capacitance value between the respective electrode plates.
[0017]
The basic configuration of the capacitive load detection device according to the present embodiment is constructed by the above-described units. However, for practical use, it has additional components (not shown). For example, in order to prevent the occurrence of displacement between the upper plate 1, the lower plate 2, and the intermediate plates 41, 42, 43, to increase the efficiency of the measurement, to increase the uniformity of the load application, and to stabilize the measurement. It has an additional component for the purpose of improving the reproducibility, improving the repetitive measurement performance, and the like.
[0018]
One of the additional components is a connecting plate (not shown). This connecting plate makes it possible to freely move up and down between the upper plate 1 and the lower plate 2 and to prevent lateral movement. By attaching connecting plates having this purpose in four directions between the upper plate 1 and the lower plate 2, movement in the vertical Z-axis direction is allowed, and movement in the XY-axis directions is restricted. In addition to the connecting plate for connecting the upper plate 1 and the lower plate 2, there is a connecting part for establishing electrical connection between the electrode plates.
[0019]
As a configuration example for securing a mechanical position between the pole plates, there is a method of protruding the upper and lower ends of the spring upward or downward. More specifically, for example, the upper end is bent upward, and the lower end is bent downward. Further, each pole plate is provided with a hole for taking in the above-mentioned bent portion, and the mechanical position is mutually determined.
[0020]
The upper plate 1, the lower plate 2, and the intermediate plate are alternately connected, and the configured capacity measurement spaces are connected in parallel to increase the detection capacity, increase the amount of change in the measurement capacity, and stabilize the measurement. The sensitivity is improved. For these purposes, the interval length between the intermediate plates 41, 42, 43 is made smaller, and the area to be opposed is enlarged.
[0021]
For the above purpose, the structure of the corners of the intermediate plates 41, 42, 43 is asymmetric between the upper and lower plates, and constitutes a portion that does not overlap between the adjacent electrode plates. The three intermediate plates 41, 42, and 43 in the embodiment have the same processing structure but have non-identical upper and lower shapes, and furthermore, by arranging the overlapping direction upside down, adjacent electrode plates do not overlap. Make up the part. In this configuration, the electrical connection between adjacent plates is made non-overlapping to facilitate alternate electrical connection.
[0022]
In the capacitive load detecting device of the present embodiment, a four-pole capacitive component is connected in parallel by the upper plate 1, the three intermediate plates 41, 42, 43, and the lower plate 2, so that one capacitive type load detecting device is provided. A load detector is formed. Each of the upper plate 1, the lower plate 2, and the second intermediate plate 42 is electrically connected to be a negative pole. Further, the first intermediate plate 41 and the second intermediate plate 43 are electrically connected to each other to be a positive pole. The minus pole (-) and the plus pole (+) shown in FIG. 3 are connected to an oscillation circuit (not shown), and the change value of the oscillation frequency output from the oscillation circuit is converted as a measured value.
[0023]
The capacitance value formed by each plate changes in parallel according to the amount of load applied to the upper plate 1 serving as the loading plate. Further, intermediate plates 41, 42 and 43 are provided between the upper plate 1 and the lower plate 2 to subdivide the space. Thereby, the area of the electrode plate is enlarged and the distance between the electrode plates is reduced. The capacitances formed between these adjacent electrode plates are connected in parallel and connected to the oscillation circuit.
[0024]
According to the above configuration, the number of capacitances formed between the electrode plates increases. Further, the distance between the electrode plates is reduced, and as a result, the constituent capacitance value is increased. Experiments have shown that it is possible to further reduce the amount of change in the detected capacitance by increasing the constituent capacitance. Based on these conditions, the oscillation frequency of the oscillation circuit can be stabilized and the effective change amount can be increased, the detection signal obtained can be enlarged, and the detection sensitivity can be increased.
[0025]
Further, in the above-described embodiment, the load received by the load plate of the upper plate is directly transmitted to the lower plate by the four load detection springs 3a, 3b, 3c, and 3d. As a result, the intermediate springs 51, 52, and 53, which are arranged between the upper plate 1 and the lower plate 2 and hold the intermediate plates 41, 42, and 43, which are pole plates, at equal intervals, have a small load capacity. Good. Therefore, the overall configuration is further simplified, and a more compact and thinner configuration can be achieved.
[0026]
In addition, the capacitive load detection device of the above embodiment accommodates the intermediate plates 41, 42, and 43 in the space formed by the upper and lower plates 1 and 2, as is known from FIGS. It is composed. When the intermediate plates 41, 42 and 43 are smaller than the upper and lower plates 1 and 2, the formed capacitance value becomes smaller, which causes a reduction in load detection sensitivity. However, on the other hand, it has been confirmed that the variation in the detected capacitance value due to the non-uniform displacement of the four load detection springs 3a, 3b, 3c and 3d due to the variation in the position of the center of gravity of the load has been confirmed. Therefore, by making the intermediate plates 41, 42, and 43 smaller than the outer dimensions of the upper and lower plates 1 and 2, it is possible to further reduce the amount of change in measured values.
[0027]
In the capacitive load detecting device configured based on the above requirements, the number of capacitive components increases. Further, the distance between the electrode plates is reduced, and as a result, the constituent capacitance value is increased. By increasing the constituent capacitance, the amount of change in the detected capacitance can be reduced. Based on these conditions, the oscillation frequency of the oscillation circuit can be stabilized and the effective change amount can be increased, the detection signal obtained can be enlarged, and the detection sensitivity can be increased.
[0028]
The above embodiment is an example of a preferred embodiment of the present invention. However, the present invention is not limited to this, and various modifications can be made without departing from the scope of the present invention.
[0029]
【The invention's effect】
As is clear from the above description, in the capacitive load detecting device of the present invention, the upper plate is vertically movable according to the magnitude of the load amount, and the load detecting spring is moved to the upper plate according to the magnitude of the load amount. And the interval length between the lower plate and the lower plate. An intermediate plate constituting at least two spaces accommodated in an intermediate portion between the upper plate and the lower plate, and an applied load is detected based on a change in a capacitance value based on a plurality of formed spaces. It is possible to do. With this configuration, the constituent capacitance value is increased, and the amount of change in the detected capacitance can be reduced. Based on these conditions, the oscillation frequency of the oscillation circuit can be stabilized and the effective change amount can be increased, the detection signal obtained can be enlarged, and the detection sensitivity can be increased.
[Brief description of the drawings]
FIG. 1 shows a configuration example of an embodiment of a capacitive load detection device of the present invention, and is a plan view from above with a top plate removed.
FIG. 2 is a side view corresponding to the plan view of FIG.
FIG. 3 is a conceptual diagram showing a connection example between electrode plates.
FIG. 4 is a side view showing a configuration example of a conventional capacitive load detection device.
[Explanation of symbols]
1 upper plate 2 lower plates 3a, 3b, 3c, 3d load detecting springs 41, 42, 43 intermediate plates 51, 52, 53, 54 intermediate springs

Claims (4)

An upper plate that is made movable according to the load value to which the load to be measured is applied,
A lower plate that holds the upper plate,
A load detection spring disposed between the upper plate and the lower plate to change a distance between the upper plate and the lower plate according to the load value,
An intermediate plate that is housed and arranged in a space formed by the upper plate and the lower plate, and divides the space into at least two layers;
The load value is detected by a change amount of a capacity based on a change in an interval distance between the upper plate and the lower plate in an interval formed by any one of the upper plate, the intermediate plate, and the lower plate. And a capacitive load detector. The capacitive load detecting device according to claim 1, further comprising at least one intermediate spring between each of the upper plate and the intermediate plate and between the intermediate plate and the lower plate. The upper plate and the lower plate are used as one pole, and the intermediate plate is used as the other pole, and the capacity constituted by the two-layered space portion is connected in parallel, and the load value can be detected based on a change in the capacity. The capacitive load detection device according to claim 1 or 2, wherein: An oscillation circuit that changes an oscillation frequency in accordance with a change in the size of the capacitance is further provided, and the load can be measured in accordance with the oscillation frequency based on a change in the capacitance based on the space. The capacitive load detection device according to any one of claims 1 to 3, wherein:

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