JP2002071485A - Force detection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a force detection device capable of easy mounting at a low cost. SOLUTION: This device is provided with electric conductive lands DX1, DX2 which are formed on a substrate 1, an electric conductive rubber or elastomer, a contact resistance generating plate 2B formed of a plurality of small protrusions t facing to the electric conductive lands DX1, DX2 and a common electric conductive land DC which is formed on the substrate 1 and is always in the electric conduction state to the contact resistance generating plate 2B. When the contact resistance generating plate 2B is pressed against the electric conductive lands DX1, DX2 by force or pressure, due to amount and direction of force or pressure distribution, small protrusions t are crushed, accordingly, the contact area between the contact resistance generating plate 2B and the electric conductive lands DX1, DX2, becomes larger so the contact resistance becomes smaller. As a result, the electric resistance between the common electric conductive land DC and the electric conductive lands DX1, DX2 is made smaller.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a force detecting device.

[0002]

2. Description of the Related Art As a force detecting device, for example,
-49029.

[0003] As shown in FIG.
Form a semiconductive layer and conductor pattern on the ET film,
The pressure distribution and the magnitude are measured by the contact resistance between the conductor pattern C and each of the conductor patterns N, S, E, W.

However, in the above force detecting device, a special semiconductive layer must be printed on the PET film, and a connector and an anisotropic conductive tape are required for connecting the conductive pattern to the circuit board. Therefore, there is a problem that the cost is high and mounting is difficult.

[0005] Therefore, the industry dealing with this type of force detection device has been waiting for the development of a low-cost and easy-to-implement force detection device.

[0006]

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a low cost and easy to mount force detecting device.

[0007]

Means for Solving the Problems (Invention of Claim 1)
The force detecting device according to the present invention has two or more conductive lands formed on a substrate or a film, and a large number of microprojections formed on a surface which is made of conductive rubber or elastomer and faces the conductive land. A contact resistance generating plate, and a common conductive land formed on a substrate or a film and always in electrical contact with the contact resistance generating plate. When a force or pressure is applied that pushes into the land, the minute projections are crushed according to the magnitude and direction of the force or the pressure distribution, and the contact area between the contact resistance generating plate portion and the conductive land increases. Accordingly, the contact resistance is reduced, and accordingly, the resistance between the common conductive land and the conductive land is reduced. (Invention of claim 2) A force detecting device according to the present invention comprises: two or more conductive lands formed on a substrate or a film;
A contact resistance generating plate formed of a non-conductive rubber or elastomer having a large number of fine projections on at least one surface and having a conductive ink or paint applied to a surface where the fine projections are present; And a common conductive land which is formed and is always in contact with and electrically connected to the contact resistance generating plate, and a force or pressure is applied to push the contact resistance generating plate toward the conductive land. Occasionally, the minute projections are crushed in accordance with the magnitude and direction of the force or the pressure distribution, and the contact area between the contact resistance generating plate portion and the conductive land increases, thereby reducing the contact resistance. The resistance between the land and the conductive land is reduced. (The invention according to claim 3) The force detecting device according to the present invention relates to the invention according to claim 1 or 2, wherein the conductive land has an angle of 90 °.
The four contact resistances are arranged at intervals, and the four contact resistances generated between the conductive land and the contact resistance generating plate change.
The magnitude of the force acting on the contact resistance generating plate in the X-axis direction and the Y-axis direction and the direction or pressure distribution can be detected. (Invention according to claim 4) The force detecting device according to the present invention relates to the invention according to claim 1 or 2, wherein the conductive land has an angle of 45 °.
Eight are arranged at intervals, and by the change of eight contact resistances generated between the conductive land and the contact resistance generating plate,
The magnitude of the force acting on the contact resistance generating plate in eight directions and the direction or pressure distribution can be detected. (The invention according to claim 5) The force detecting device according to the present invention relates to the invention according to claim 1 or 2, wherein the conductive land has 180 points.
Are arranged at an interval of two degrees, and changes in two contact resistances generated between the conductive land and the contact resistance generating plate cause a change in the X-axis direction or the Y-axis direction acting on the contact resistance generating plate. The magnitude and direction of the force or the distribution of the pressure can be detected. According to a sixth aspect of the present invention, there is provided a force detecting device according to any one of the first to fifth aspects, wherein the minute projections formed on the contact resistance generating plate always contact the conductive land group. are doing.

The function of the force detecting device of the present invention will be clarified in the following embodiments of the present invention.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described with reference to the drawings showing embodiments. [Embodiment 1] FIG. 1 is a sectional view of a force detecting device S according to an embodiment of the present invention, and FIG. 2 shows a conductive land and a common conductive land on a substrate 1 constituting the force detecting device S. I have.

As shown in FIG. 1, the force sensor S includes a substrate 1, an operation unit 2 disposed opposite to the substrate 1, and a fixing unit 3 for fixing the operation unit 2 on the substrate 1. Have been.

The substrate 1 is formed of a thin printed circuit board as shown in FIG. 1, and has four circular conductive lands DX1, DX2, DY1, and D divided on the upper surface as shown in FIG.
Y2 is arranged on the XY axis at an equal distance from the origin O, and the conductive lands DX1, DX around the origin O are centered.
2, an annular common conductive land DC surrounding DY1 and DY2 is provided. The conductive lands DX1, DX2, DY1, D
The Y2 and the common conductive land DC are formed of a copper layer formed on the substrate 1 with a solder layer, gold or silver plating, carbon printing, or solder welding. It is. The conductive lands DX1, DX2, D
Y1 and DY2 and the common conductive land DC are electrically insulated from each other, and are drawn out at appropriate positions on the substrate 1 by terminals.

As shown in FIGS. 1 and 3, the operation unit 2 includes an operation main body 2A made of a non-conductive rubber or a non-conductive elastomer, and a contact resistance generation made of a conductive rubber or a conductive elastomer. It is formed integrally with the plate 2B.

As shown in FIG. 1, the operation main body 2A includes a thin plate portion 21 having a circular shape in plan view and a button portion 20 integrally formed at the center of the upper surface of the thin plate portion.

As shown in FIGS. 1 and 2, the contact resistance generating plate 2B is formed in an inverted dish shape having the same diameter as the thin plate portion 20, and is opposed to the conductive lands DX1, DX2, DY1, and DY2. Is a shallow recess 22 and the recess
A large number of minute projections t are formed on the bottom surface of 22. The conductive rubber used for the contact resistance generating plate 2B has a volume resistance of about 0.1 to 100 Ω · cm which is generally available. On the other hand, this contact resistance generating plate 2B
As shown in FIG. 1, the outer peripheral flat portion around the concave portion 22 on the lower surface of the common conductive land DC formed on the substrate 1
Closely adhered to. As shown in FIG. 1, the fixing portion 3 is formed in an annular shape having an inverted L-shaped cross section, and the horizontal piece presses the upper surface of the mounting portion 21.

Since the force detecting device S according to the embodiment of the present invention has the above-described configuration, it functions as follows.

As shown in FIG. 3, when the button portion 20 is pushed in so that the contact resistance generating plate 2B comes into contact with the conductive land DX1, a large number of small projections t formed on the surface of the contact resistance generating plate 2B are removed. It comes into contact with the conductive land DX1,
A contact resistance is generated between the contact resistance generating plate 2B and the conductive land DX1. Through this contact resistance and the resistance of the contact resistance generating plate 2B, the conductive land DX1 on the substrate 1 and the common conductive land DC are electrically connected. Assuming that this contact resistance is RX1, the contact resistance RX1 is set so that the minute projection t of the contact resistance generating plate 2B is crushed and adheres to the conductive land DX1 according to the magnitude and direction of the force applied to the button portion 20. Because
The resistance value of the contact resistance RX1 decreases in inverse proportion to the magnitude of the force. Note that the resistance value of the contact resistance RX1 changes more gently with respect to the magnitude of the pressing force of the button portion 20 and the converged resistance value is larger than when there is no minute protrusion t. The same applies to the other conductive lands DX2, DY1, and DY2.

FIG. 4 shows this as a circuit. In FIG. 4, R0 is the resistance value of the contact resistance generating plate 2B itself, but can be ignored because it is smaller than the contact resistance. Note that, depending on the direction and magnitude of the pressing force of the button portion 20, the contact resistance generating plate 2B may be connected to the conductive lands DX1, DX2, D2.
It may touch two or more of Y1 and DY2, but this does not detract from the object of the present invention.

If an appropriate application circuit is connected to the circuit shown in FIG. 4, it is possible to detect the magnitude and direction of the force pressing the button portion 20. FIG. 5 shows an example of the application circuit.
In FIG. 5, R1 to R4 are fixed resistors, and RX1 to Rx
Y2 is the contact resistance generating plate 2B and the conductive lands DX1, DX2, DY
1, Contact resistance with DY2.

Here, if the voltage (VX1−VX2) is calculated by an appropriate method, the magnitude of the component force in the X-axis direction can be detected.
Similarly, if the voltage (VY1−VY2) is calculated by an appropriate method, the magnitude of the component force in the Y-axis direction can be detected. When no force is applied to the button section 20, the circuit current i does not flow because each contact resistance is infinite. This is very effective in terms of power saving, and can be provided as a joystick for mobile phones, personal computers, and the like.

As described above, it is possible to provide a joystick at low cost by using a conductive rubber, a general-purpose rubber, or a printed circuit board which is easily available without using a semiconductive layer formed of a special ink or the like. I understand.

Changing the relationship between the pressing force of the button portion 20 and the multi-contact resistance value to change the operation feeling can be achieved by changing the size and number of the minute protrusions t on the conductive rubber surface, the resistance value of the conductive rubber or the conductive rubber. It is possible by changing the hardness of the conductive rubber. The larger the minute protrusions t and the smaller the number, the larger each contact resistance value for a constant force.

In the first embodiment, the contact resistance generating plate 2B is normally prevented from contacting the conductive lands DX1, DX2, DY1, DY2. However, the present invention is not limited to this. The resistance generating plate 2B may lightly contact the conductive lands DX1, DX2, DY1, DY2. [Second Embodiment] FIG. 6 is a sectional view of a force detecting device S according to a second embodiment of the present invention.

In this force detecting device S, as shown in FIG. 6, the operating section 2 includes a button section 20, an annular mounting section 23 having a diameter larger than the button section 20, and an outer periphery of the button section 20. The thin-walled deformation part 24 that connects the surface and the upper end face of the mounting part 23 all around
And is formed separately from the contact resistance generating plate 2B.

The contact resistance generating plate 2B is, as shown in FIG.
An outer peripheral portion of the upper and lower surfaces is flat f (a minute protrusion t
And a large number of minute protrusions t are formed on the inner portion on both upper and lower surfaces. The contact resistance generating plate 2B is attached to the mounting portion 23 as shown in FIG.
In this fixed state, the small projections t formed on the lower surface side are electrically conductive lands D.
The flat f-plane formed on the lower surface side is in strong contact with the common conductive land C so as to make light contact with X1, DX2, DY1, and DY2. That is, the contact resistance between the contact resistance generating plate 2B and the conductive lands DX1, DX2, DY1, DY2 is large, and the contact resistance between the contact resistance generating plate 2B and the common conductive land DC is small.

When the button portion 20 is not pushed, the lower surface of the button portion 20 is not in contact with the contact resistance generating plate 2B.

When the operating section 20 is pushed in, the button section 20 pushes down the contact resistance generating plate 2B according to the magnitude and direction of the force. The contact resistance between the lands DX1, DX2, DY1, and DY2 and the common conductive land DC changes. Normally, the minute protrusions t are formed on the conductive lands DX1, DX2, DY1, DY2.
It may be configured so as not to contact with. [Embodiment 3] In the force detection device S of this embodiment, FIG.
As shown in (1), the button-shaped operation part is eliminated, and the decorative panel 4 having flexibility is arranged on the contact resistance generating plate 2B.

Accordingly, when the decorative panel 4 is pressed with a finger, the contact resistance between the conductive lands DX1, DX2, DY1, and DY2 and the common conductive land DC is reduced according to the magnitude of the force and the position where the force is applied. Change. [Other Embodiments] In the above embodiment, four conductive lands are formed on the substrate. However, the present invention is not limited to this. Two conductive lands may be formed, or eight conductive lands may be formed. Conductive lands may be formed, or more conductive lands may be formed. In short, the conductive lands may be formed in accordance with the number of directions in which the force is applied.

In the force detecting device of the above-described embodiment, when a pressure is applied such that the contact resistance generating plate 2B is pushed toward the conductive land, the distribution of the pressure can be detected by substantially the same principle.

Instead of the force detecting device of the above embodiment, the contact resistance generating plate is made of non-conductive rubber or elastomer having a large number of minute projections on at least one side, and FIG.
As shown in (1), a conductive ink INC or paint may be applied to the surface on which the fine protrusions are present.

In the force detecting device of the above embodiment, the substrate 1 can be changed to a film. [Excellent points of the force detecting device according to the embodiment of the present invention] This force detecting device basically includes a substrate 1 on which conductive lands and a common conductive land are formed, a contact resistance generating plate 2B, and a fixing portion 3. Can be composed of Therefore, a special semiconductive layer must be printed on the PET film, and it is very inexpensive when compared with the conventional one that requires a connector or an anisotropic conductive tape for connecting the conductor pattern and the circuit board. And easy to implement.

[0031]

The present invention has the following effects since it has the above-described configuration.

As is clear from the description of the embodiments of the present invention, a low-cost and easy-to-implement force detection device can be provided.

[Brief description of the drawings]

FIG. 1 is a sectional view of a force detecting device according to a first embodiment of the present invention.

FIG. 2 is a plan view of a conductive land formed on a substrate constituting the force detection device.

FIG. 3 is a cross-sectional view when a force is applied to a button portion of the force detection device.

FIG. 4 is an electric circuit diagram showing a relationship between the conductive lands, a common conductive land, and a contact resistance generating plate.

FIG. 5 is a diagram of an application circuit that can be adopted in this embodiment.

FIG. 6 is a sectional view of a force detecting device according to a second embodiment of the present invention.

FIG. 7 is a sectional view of a force detection device according to a third embodiment of the present invention.

FIG. 8 is a sectional view of a contact resistance generating plate according to another embodiment.

FIG. 9 is a conceptual diagram of a prior art force detection device.

[Explanation of Symbols] S force detection device DX1 conductive land DX2 conductive land DY1 conductive land DY2 conductive land DC common conductive land t microprojection 1 substrate 2 operation unit 2A operation subject 2B contact resistance generating plate 20 button unit 21 thin plate unit 3 fixing unit

Claims (6)

[Claims] 1. A contact comprising two or more conductive lands formed on a substrate or a film, and a plurality of fine projections formed on a surface opposed to the conductive lands made of a conductive rubber or elastomer. A resistance generating plate, and a common conductive land formed on a substrate or a film and always in contact with and electrically connected to the contact resistance generating plate, wherein the contact resistance generating plate faces the conductive land. When a force or pressure is applied that pushes in, the small protrusions are crushed in accordance with the magnitude and direction of the force or the pressure distribution, and the contact area between the contact resistance generating plate portion and the conductive land is increased, so that the contact resistance is increased. And a resistance between the common conductive land and the conductive land is reduced accordingly. 2. A non-conductive rubber or elastomer having a plurality of fine protrusions on at least one surface and a conductive film formed on at least one surface of the substrate or film. A contact resistance generating plate formed by applying a conductive ink or paint, and a common conductive land formed on a substrate or a film and always in contact with and electrically connected to the contact resistance generating plate. When a force or pressure that pushes the contact resistance generating plate toward the conductive land is applied, the minute projections are crushed according to the magnitude and direction of the force or the pressure distribution, and the contact resistance generating plate portion and the conductive member are electrically conductive. The contact resistance is reduced by increasing the contact area of the land, and the resistance between the common conductive land and the conductive land is reduced accordingly. Force detector. 3. Four conductive lands are arranged at 90 ° intervals, and act on the contact resistance generating plate due to a change in four contact resistances generated between the conductive land and the contact resistance generating plate. 3. The force detecting device according to claim 1, wherein the magnitude of the force in the X-axis direction and the Y-axis direction and the distribution of the direction or the pressure are detected. 4. Eight conductive lands are arranged at 45 ° intervals and act on the contact resistance generating plate by a change in eight contact resistances generated between the conductive land and the contact resistance generating plate. The force detecting device according to claim 1 or 2, wherein the force in eight directions and the distribution of the directions or the pressures can be detected. 5. Two conductive lands are arranged at 180 ° intervals, and act on the contact resistance generating plate by a change in two contact resistances generated between the conductive land and the contact resistance generating plate. 3. The force detection device according to claim 1, wherein the magnitude of the force in the X-axis direction or the Y-axis direction and the distribution of the direction or the pressure are detected. 6. The force detecting device according to claim 1, wherein the minute projection formed on the contact resistance generating plate is always in contact with the conductive land group.