JPH0682318A - Electric type pressure-sensitive sensor - Google Patents

Abstract

PURPOSE:To digitalize detection data as pressure and contrive improvement of detection precision by forming so that a contact area for a circuit board of press electrodes may be widened due to increase of pressure. CONSTITUTION:When a press electrode 22a of a size covering the whole arrangement area of a ground electrode 21b and a plurality of signal electrodes 21c presses down a rubber cap 23 of the outer face of a ceiling wall of an actuator 22 with the press tool 24, it is bent and lowered along an arc face 24a of the press tool 24 together with the cap 23. Accordingly, when the press tool 24 is gradually lowered, the electrode 22a is brought into contact with the circuit board 21 as it bestrides the electrode 22b and each signal electrode arrangement area while circularly being widened with S point as the center. For instance an electrode 21c3 is conducted in the electrode 21b and a circle C1, electrodes 21c3,4 in a circle C2, electrodes Cc3,4,2 in a circle C3, electrodes 21c3,4,2,5, in a circle C4 and electrodes Cc3,4,2,5,1 in a circle C5, respectively. Accordingly an electric potential for a ground line 21 of terminals S1-S5 connected to each signal electrode is detected, so that positive pressure of the press tool 24 corresponding to the size of the circles can be digitally detected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of an electric pressure sensitive sensor for detecting mechanical pressure digitally, and more particularly to an electric pressure sensitive sensor which digitizes detection data and improves detection accuracy.

A pressure-sensitive sensor for electrically detecting mechanical pressure at low cost is generally one using a pressure conductive rubber, and such a sensor can be used even when the pressure is digitally detected. Many.

[0003]

2. Description of the Related Art FIG. 4 is a principle configuration cross-sectional view showing an example of a conventional electric pressure-sensitive sensor, and FIG. 5 is a view showing an example of detection data.

In FIG. 4, an electric pressure sensor (hereinafter simply referred to as a pressure sensor) 1 has two electrodes 11a and 11b facing each other on its surface.
The circuit board 11 on which the pattern is formed and the electrodes 11a and 11
A pressure conductive rubber 12 formed by mixing carbon (C) particles 12b as a conductor into a silicon rubber 12a having a size capable of at least covering the space between b and a pressing plate attached to the upper surface thereof. 13 and 13 as main constituent members.

The pressure-conducting rubber 12 is in a natural state, that is, in a state where no pressure is applied, each carbon particle 12
It has the property as an insulator because there is no contact between b, but it has the property of becoming a conductor by the contact between the carbon particles 12b when pressure is applied, and the conductivity changes depending on the magnitude of the pressure. Is formed.

In this case, the change in conductivity with respect to the change in pressure can be changed linearly or non-linearly depending on the size of the carbon particles, the mixing ratio, and the like. Further, both ends of the electrodes 11a and 11b are connected to a circuit (not shown) on the outer sides thereof so that the resistance value between the electrodes 11a and 11b can be detected.

Therefore, when the pressure sensor 1 is brought into contact with the object whose pressure is to be detected, the pressing plate 13 is pressed, and as a result, the pressure of the object is detected by the electrode.
It can be detected as the resistance value between 11a and 11b.

FIG. 5 showing an example of the detection data shows the pressure of the object and the electrode 11a, where the horizontal axis X is the pressure P of the object and the vertical axis Y is the resistance value R between the electrodes 11a and 11b. This is a plot of the relationship between 11b and resistance.

That is, when the pressure of the object is "0", the electrode 11
a, a ₁ point and the maximum pressure of the subject "p" at the electrode 11a when the resistance value ∞ between 11b, is between a _2-point when the resistance value r between 11b, for example, approximately in the curve A A case where the curve B changes linearly is shown, and a curve B shows an upward curve and a curve C shows a downward curve.

Therefore, by obtaining these curves corresponding to the pressurized conductive rubber 12 to be used in advance, for example, in the case of the curve A, the detected resistance value r _{1 can be used} to determine the pressure p ₁ of the subject at that time. The pressure-sensitive sensor 1 that can detect can be configured.

The pressure-sensitive sensor 1 can detect the pressure of the subject with a simple structure without requiring any special technique.

[0012]

However, in the pressure-sensitive sensor 1 having the above-described structure, the distribution density of the carbon particles 12b mixed in the pressure conductive rubber 12 has a great influence on the resistance value to be detected. Instability and variations easily occur, and the characteristics of the silicone rubber itself greatly affect the detected resistance value.

Therefore, even when the pressure of the object is inexpensively and digitally detected, there is a problem that an error is likely to occur in the detection accuracy of the resistance value and the reproducibility is likely to be poor.

[0014]

The above-mentioned problem is an electric pressure-sensitive sensor that digitizes and detects mechanical pressure.
A rectangular ground electrode connected to the ground line and a plurality of signal electrodes each having an output terminal along one side of the one side in the longitudinal direction of the ground electrode are formed, and each of the signal electrodes is connected via an individual resistor. A circuit board connected to each power line,
A rectangular dish-like plate that is positioned and fixed on the circuit board so as to lie down on the circuit board around the midpoint between the ground electrode of the circuit board and the plurality of signal electrode arrangement areas, and the ground electrode and the plurality of signals are provided on the inner surface of the ceiling wall. An actuator made of an insulating elastic body in which a pressing electrode having a size large enough to substantially cover the electrode arrangement area is formed, and an intermediate point between the ground electrode of the circuit board above the actuator and the plurality of signal electrode arrangement areas. This is achieved by an electric pressure-sensitive sensor that is configured to include at least a pressing tool that has a circular arc surface at its lower end that can move up and down around a central axis.

[0015]

When the spherical projection of the elastic body is pressed against the flat surface, the contact area of the spherical projection with the flat surface can be increased as the pressing force is increased.

Further, for example, a rectangular ground electrode and a plurality of signal electrodes are formed on the circuit board in the vicinity of one side of the longitudinal direction of the ground electrode, and a plurality of signal electrodes are formed on the circuit board. When the ground electrode and the signal electrode are electrically connected after being connected to one power supply line, the potential of the signal electrode electrically connected to the ground electrode can be digitally changed depending on the number of signal electrodes electrically connected to the ground electrode.

Therefore, in the present invention, the ground electrode and the plurality of signal electrodes as described above are formed on the pattern-formed circuit board so that the contact area with the circuit board becomes wider as the pressing force increases. A pressure electrode is provided to configure an electric pressure-sensitive sensor in which detection data as pressure is digitized.

This means that by arranging the pressing electrode at an intermediate portion between the ground electrode and the signal electrode arrangement region, the number of signal electrodes that are electrically connected to the ground electrode can be increased as the pressing force increases. As a result, the potential of the signal electrode made conductive to the ground electrode can be digitally changed by the fluctuation of the pressing force, and the electrode on the circuit board and the pressing electrode are brought into direct contact with each other. It is possible to eliminate the instability and variation of the resistance value that is found in conductive rubber.

Therefore, it is possible to realize a pressure-sensitive sensor which can detect the pressure of a subject digitally and accurately with a simple structure without requiring any special technique.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a principle configuration diagram for explaining a pressure-sensitive sensor according to the present invention. (1-1) is a conceptual diagram of the configuration and (1-2) is an extracted circuit configuration. .

FIG. 2 is a diagram showing the operating state in time series, and FIG. 3 is a diagram for explaining an example of the construction of the pressure-sensitive sensor. In FIG. 1, the pressure-sensitive sensor 2 has a rectangular ground electrode 21b connected to the ground wire 21a on the surface and a plurality of signal electrodes (five in the figure) along the edge near one edge in the longitudinal direction.
21c _{1 to} 21c ₅ are further formed, and each of the signal electrodes 21c _{1 to} 21c ₅ is connected to one power supply line 21e via an individual resistor 21d, and a square plate-shaped ceiling wall An actuator 22 made of an insulating elastic material such as urethane rubber having a pressure electrode 22a coated with a conductive paint, for example, on its inner surface,
A plate-shaped rubber cap 23 attached to the outer surface of the ceiling wall of the actuator 22, and a position slightly deviated from the center position of the rubber cap 23 in the longitudinal direction of the ground electrode 21b, that is, the ground electrode 21b and a plurality of signal electrodes. The pressing tool 24 is located above a position (for example, point S in the figure) slightly deviated in the longitudinal direction of the ground electrode 21b from the center position with respect to the formation region, and has a vertically movable tip having an arc surface 24a. It is configured as a member.

The pressing electrode 22a having a size capable of substantially covering the entire arrangement area of the ground electrode 21b and the plurality of signal electrodes 21c is the rubber cap 23 on the outer surface of the ceiling wall of the actuator 22 and the pressing tool 24. It is formed so that when it is pressed down with the rubber cap 23, the rubber cap 23 and the rubber cap 23 are bent while following the circular arc surface 24a of the pressing tool 24.

Therefore, from the state shown in FIG.
Is gradually lowered, the pressing electrode 22a becomes a ground electrode.
The circuit board 21 is in contact with the circuit board 21 while straddling 21b and each signal electrode arrangement region and expanding in a circle centering on the point S.

That is, for example, in the circle C ₁ , the ground electrode 21
b and the signal electrode 21c ₃ become conductive, and in the circle C ₂ the ground electrode 21b 3
And the signal electrodes 21c _{3 and} 21c ₄ and the circle C ₃
And signal electrodes 21c _3, 21c _4, 21c ₂ and circle C ₄ the ground electrode 21b and signal electrodes 21c _3, 21c _4, 21c _4, 21c ₅ are circles C
_{In 5} , the ground electrode 21b and the signal electrodes 21c _3, 21c _4, 21c _{4 ,} 2
1c _{5 and} 21c ₁ are in conduction with each other.

Therefore, output terminals S _1-
By detecting the potential of S ₅ with respect to the ground line 21a, the pressing force of the pressing tool 24 corresponding to the size of the circle can be digitally detected.

FIG. 2 is a side cross-sectional view showing the connection state between the pressing electrode 22a and each signal electrode on the circuit board 21, and (2-1) is shown in FIG. (1-1) represents the time corresponding to (1-2), (2-2) represents the time corresponding to circle C _{1 in} Fig. 1, and (2-3) represents the time corresponding to circle C _{5 in} Fig. 1. There is.

That is, in (2-2), since the actuator 22 is curved along with the rubber cap 23 along the arc surface 24a of the pressing tool 24, the pressing electrode 22a contacts only the ground electrode 21b and the signal electrode 21c _3. Is in a state of

Therefore, the potential of the signal electrode 21c ₃ at this time is detected between the output terminal S ₃ connected to the signal electrode 21c ₃ and the ground line 21a connected to the ground electrode 21b as described in FIG. be able to.

Further, in (2-3) where the pressing force of the pressing tool 24 is large, the pressing electrode 22a is in contact with all of the ground electrode 21b and the signal electrode. Therefore, the potential of the signal electrode at this time can be detected between the output terminal S ₁ connected to the signal electrode 21c ₁ and the ground line 21a connected to the ground electrode 21b, as described with reference to FIG.

FIG. 3 is a side sectional view showing an example of the construction of a pressure-sensitive sensor. The pressure-sensitive sensor 3 includes a circuit board 21, an actuator 22, a rubber cap 23, a pressing tool 24 and the circuit board described in FIG. Microcomputer implemented in 21 3
1, and a housing 3 for positioning and accommodating each of these members
It consists of 2 and.

The pressing tool 24 mounted at a predetermined position on the ceiling wall of the housing 32 is always pushed up to the inner surface of the ceiling wall by the coil spring 33, and the pressing tool 24 is mounted on the microcomputer 31 on the circuit board 21. Is the output terminal described in FIG.
It has a function to calculate the digital electric potential signal obtained from S _{1 to} S ₅ and convert it to pressure.

When the pressure-sensitive sensor 3 is brought into contact with the object whose pressure is to be detected, the pressing tool 24 descends as described with reference to FIG. 1, and as a result, the means described below with reference to FIG. The pressure of the subject can be detected.

[0033]

As described above, according to the present invention, it is possible to provide an electric pressure-sensitive sensor which digitizes detection data as pressure and improves the detection accuracy of the data.

In the description of the present invention, the case where the pressing electrode formed on the inner surface of the ceiling wall of the actuator is flat is taken as an example, but the same effect can be obtained even if the pressing electrode is curved to project toward the circuit board. Can be obtained.

In the description of the present invention, the case where the rubber cap is attached to the outer surface of the ceiling wall of the actuator is illustrated, but the thickness of the ceiling wall of the actuator is appropriately set to reduce the rubber cap. Can also obtain the same effect.

[Brief description of drawings]

FIG. 1 is a principle configuration diagram illustrating a pressure-sensitive sensor according to the present invention.

FIG. 2 is a diagram showing operating states in time series.

FIG. 3 is a diagram illustrating an example of an implementation configuration as a pressure-sensitive sensor.

FIG. 4 is a sectional view of the principle configuration showing an example of a conventional electric pressure-sensitive sensor.

FIG. 5 is a diagram showing an example of detection data.

[Explanation of symbols]

2,3 Electric pressure sensor 21 Circuit board 21a Ground wire 21b Grant electrode 21c, 21c _{1 to} 21c ₅ Signal electrode 21d Resistor 21e Power wire 22 Actuator 22a Push electrode 23 Rubber cap 24 Push tool 24a Circular surface 31 Microcomputer 32 Case 33 Coil spring

Claims (1)

[Claims] 1. An electric pressure-sensitive sensor for detecting mechanical pressure by digitizing it, which comprises a rectangular ground electrode (21) connected to a ground wire (21a).
b) to the longitudinal direction one end side near the plurality of signal electrodes along a said end edge has an output terminal (21c ₁ ~21c ₅₎ and is formed further respective signal electrodes (21c ₁ ~21c ₅₎ individual Resistor (21d)
Circuit board connected to one power line (21e) via
(21) and a rectangular dish shape that is positioned and fixed on the circuit board so as to face down around the midpoint between the ground electrode (21b) of the circuit board (21) and the plurality of signal electrode arrangement areas. An actuator (22) made of an insulative elastic body in which the ground electrode (21b) and the pressing electrode (22a) having a size sufficient to substantially cover the plurality of signal electrode arrangement areas are formed on the inner surface of the ceiling wall.
And a pressing tool having a circular arc surface (24a) at its lower end that can move up and down around a center point near the midpoint between the ground electrode (21b) of the circuit board (21) above the actuator and a plurality of signal electrode arrangement regions. 24) An electric pressure-sensitive sensor characterized by comprising at least and