JP3413652B2 - Force detection device - Google Patents

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 For example, Japanese Patent Publication No.
There is one disclosed in Japanese Patent Publication No. 49029-490.

As shown in FIG. 9, this force detecting device has a P
Form a semi-conductive layer and a conductor pattern on the ET film,
It is assumed that the pressure distribution and magnitude are measured by the contact resistance between the conductor pattern C and each conductor pattern N, S, E, W.

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

Therefore, in the industry that deals with this type of force detecting device, it is desired to develop a force detecting device that is low in cost and easy to mount.

[0006]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a force detecting device which is low in cost and easy to mount.

[0007]

(Invention of Claim 1) A force detecting device of the present invention is composed of two or more conductive lands formed on a substrate or a film, and rubber or elastomer having conductivity. And a contact resistance generating plate having a large number of minute projections formed on the surface facing the conductive land, and is in electrical connection with the contact resistance generating plate formed on the substrate or film and always in contact with the contact resistance generating plate. The contact resistance generating plate is provided with a common conductive land, and a gap is provided between the surface of the contact resistance generating plate on which the minute projections are formed and the conductive land, and a potential difference is provided between the common conductive land and the contact resistance generating plate. When a force or pressure that pushes the resistance generating plate toward the conductive land is applied, the minute protrusions are crushed according to the magnitude and direction of the force or the pressure distribution, and the contact resistance generating plate and As the contact area of the conductive lands becomes larger, the contact resistance becomes smaller, and accordingly, the resistance between the common conductive land and the conductive lands becomes smaller. (Invention of Claim 2) The force detection device of the present invention is composed of two or more conductive lands formed on a substrate or a film, and a non-conductive rubber or elastomer having a large number of minute projections on at least one surface. And a contact resistance generating plate formed by applying a conductive ink or paint to the surface where the minute protrusions are present, and an electrically connected state which is formed on the substrate or film and is always in contact with the contact resistance generating plate. In addition to providing a common conductive land, a gap is provided between the surface of the contact resistance generating plate on which the minute protrusions are formed and the conductive land, and a potential difference is provided between the common conductive land and 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 is generated. By increasing the contact area between the green plate portion and the conductive lands, the contact resistance is reduced, and accordingly, the resistance between the common conductive land and the conductive lands is reduced. (Invention of Claim 3) The force detection device of this invention relates to the invention of Claim 1 or 2, wherein four conductive lands are arranged at 90 ° intervals, and the conductive lands and the contact resistance generating plate are provided. By changing the four contact resistances generated during the period, 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 of Claim 4) The force detection device of this invention relates to the invention of Claim 1 or 2, wherein eight conductive lands are arranged at 45 ° intervals, and the conductive lands and the contact resistance generating plate are By changing the eight contact resistances generated during the period, it is possible to detect the magnitude of the force acting on the contact resistance generating plate in eight directions and the distribution of that direction or pressure. (Invention of Claim 5) The force detection device of the present invention relates to the invention of Claim 1 or 2, wherein two conductive lands are arranged at 180 ° intervals, and the conductive lands and the contact resistance generating plate are provided. The change in the two contact resistances that occurs during the period makes it possible to detect the magnitude of the force acting on the contact resistance generating plate in the X-axis direction or the Y-axis direction and the distribution of that direction or pressure.

The function of the force detection device of the above invention will be clarified in the section of the following embodiments of the invention.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below with reference to the drawings shown as 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 conductive lands and common conductive lands on a substrate 1 which constitute the force detecting device S. There is.

As shown in FIG. 1, the force sensor S comprises a substrate 1, an operating portion 2 arranged to face the substrate 1, and a fixing portion 3 for fixing the operating portion 2 on the substrate 1. Has been done.

As shown in FIG. 1, the substrate 1 is composed of a thin printed circuit board, and as shown in FIG. 2, four circular conductive lands DX1, DX2, DY1, D are formed on the upper surface.
Y2 is arranged on the XY axis at the same distance from the origin O, and the conductive lands DX1 and DX are centered on the origin O.
An annular common conductive land DC that surrounds 2, DY1 and DY2 is arranged. Conductive lands DX1, DX2, DY1, D
The Y2 and the common conductive land DC are formed by depositing a solder layer on a copper layer formed on the substrate 1, gold plating or silver plating, carbon printing, or solder welding. There is. In addition, conductive lands DX1, DX2, D
Y1, DY2 and the common conductive land DC are electrically insulated from each other, and are led out to appropriate positions on the substrate 1 by terminals.

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

As shown in FIG. 1, the operating body 2A is composed of 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 21.

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 that of the thin plate portion 20 and faces the conductive lands DX1, DX2, DY1, DY2. The portion to be formed is a shallow recess 22 and the recess
A large number of minute protrusions t are formed on the bottom surface of 22. The conductive rubber used for the contact resistance generating plate 2B is a commercially available rubber having a volume resistance value of about 0.1 to 100 Ω · cm. On the other hand, this contact resistance generating plate 2B
As shown in FIG. 1, the outer peripheral flat surface portion around the recessed portion 22 on the lower surface of the common conductive land DC formed on the substrate 1 is
Is in close contact with. As shown in FIG. 1, the fixing portion 3 is a circular ring-shaped member having an inverted L-shaped cross section, and a horizontal piece presses the upper surface of the mounting portion 21.

The force detection device S according to the embodiment of the present invention has the above-described configuration and thus functions as follows.

As shown in FIG. 3, when the button portion 20 is pushed so that the contact resistance generating plate 2B comes into contact with the conductive land DX1, a large number of minute projections t formed on the surface of the contact resistance generating plate 2B are pressed. It comes into contact with the conductive land DX1,
Contact resistance is generated between the contact resistance generating plate 2B and the conductive land DX1. Through the 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 such that the minute projection t of the contact resistance generating plate 2B is crushed according to the magnitude and direction of the force applied to the button portion 20 so that the contact resistance RX1 comes into close contact with the conductive land DX1. So
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 force pressing the button portion 20 and the convergence resistance value is larger than that in the case where there is no minute protrusion t. This also applies to the other conductive lands DX2, DY1, 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 since it is smaller than the contact resistance, it can be ignored. Depending on the direction and magnitude of the force pressing the button portion 20, the contact resistance generating plate 2B may cause the conductive lands DX1, DX2, D
It may come into contact with two or more of Y1 and DY2, but this does not impair the object of the present invention.

If a suitable application circuit is connected to the circuit shown in FIG. 4, the magnitude and direction of the force pushing the button portion 20 can be detected. An example of the application circuit is shown in FIG.
In FIG. 5, R1 to R4 are fixed resistors, and RX1 to R4
Y2 is a contact resistance generating plate 2B and conductive lands DX1, DX2, DY
1, the contact resistance with DY2.

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 force of the component in the Y-axis direction can be detected. Further, when no force is applied to the button portion 20, each contact resistance is infinite and the circuit current i does not flow. This is very effective in terms of power saving, and can be provided as a joystick for mobile phones and personal computers.

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

Further, in order to change the operation feeling, changing the relationship between the pushing force of the button portion 20 and the multi-contact resistance value means that the size and the number of the fine protrusions t on the surface of the conductive rubber, the resistance value of the conductive rubber or the conductivity of the conductive rubber are changed. It is possible by changing the hardness of the rubber. The larger the microprotrusions t and the smaller the number, the larger each contact resistance value with respect to a constant force.

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

In this force detecting device S, as shown in FIG. 6, the operating portion 2 includes a button portion 20, an attachment portion 23 having a circular ring shape in plan view having a diameter larger than that of the button portion 20, and an outer periphery of the button portion 20. Thin-walled deforming portion 24 that connects the surface and the upper end surface of the mounting portion 23 all around.
It is made of non-conductive rubber and is formed separately from the contact resistance generating plate 2B.

The contact resistance generating plate 2B, as shown in FIG.
The outer peripheral portion of the upper and lower surfaces is flat f (the small protrusion t
The upper and lower surfaces are formed with a large number of minute protrusions t on the inner side thereof. The contact resistance generating plate 2B is attached to the mounting portion 23 as shown in FIG.
In addition, the minute protrusions t formed on the lower surface side are fixed to the conductive land D in this fixed state.
The flat f surface formed on the lower surface side is strongly contacted with the common conductive land C so as to lightly contact X1, DX2, DY1 and DY2, respectively. 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 does not come into contact with the contact resistance generating plate 2B.

Here, when the operation portion 20 is pushed in, the button portion 20 presses the contact resistance generating plate 2B in accordance with the magnitude and direction of the force, and the principle is the same as that of the first embodiment. The contact resistance between the lands DX1, DX2, DY1, DY2 and the common conductive land DC changes. In addition, normally, the small protrusions t are the conductive lands DX1, DX2, DY1, DY2.
It may be configured so as not to come into contact with. [Third Embodiment] In the force detection device S of this embodiment, as shown in FIG.
As shown in FIG. 5, the button-shaped operation portion is eliminated, and the flexible makeup panel 4 is arranged on the contact resistance generating plate 2B.

Therefore, by pushing the decorative panel 4 with a finger, the contact resistances between the conductive lands DX1, DX2, DY1, DY2 and the common conductive land DC are changed according to the magnitude of the force and the position to which the force is applied. Change. [Other Embodiments] In the above embodiment, four conductive lands are formed on the substrate, but the present invention is not limited to this, and 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, it is sufficient to form the conductive lands according to the number of detecting the direction in which the force is applied.

In the force detecting device of the above embodiment, when a pressure is applied so 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.

In place 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 surface,
As shown in, the surface on which the fine protrusions are present may be coated with conductive ink INC or paint.

In the force detection device of the above embodiment, the substrate 1 can be changed to a film. [Advantages of Force Detection Device of Embodiment of the Present Invention] This force detection device basically includes a substrate 1 on which conductive lands and common conductive lands are formed, a contact resistance generating plate 2B, and a fixing portion 3. Can consist of Therefore, it is much cheaper than the conventional one, in which a special semi-conductive layer must be printed on the PET film and a connector or an anisotropic conductive tape is required for connecting the conductor pattern and the circuit board. It is easy to implement.

[0031]

The present invention having the above-mentioned structure has the following effects.

As is apparent from the description of the section of the embodiment of the invention, it is possible to provide a force detecting device which is low in cost and easy to mount.

[Brief description of drawings]

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

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

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

FIG. 4 is a diagram in which the relationship between the conductive lands, the common conductive lands, and the contact resistance generation plate is expressed as an electric circuit.

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

FIG. 6 is a sectional view of a force detection 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 detector DX1 conductive land DX2 conductive land DY1 conductive land DY2 conductive land DC common conductive land t Small protrusion 1 substrate 2 operation part 2A Operation subject 2B Contact resistance generation plate 20 Button part 21 Thin plate 3 Fixed part

Claims (6)

(57) [Claims] 1. A contact comprising two or more conductive lands formed on a substrate or a film, and a large number of minute projections formed on a surface facing the conductive lands, the contact being made of conductive rubber or elastomer. A resistance generating plate and a common conductive land formed on a substrate or a film and being in constant contact with and electrically connected to the contact resistance generating plate. And a conductive land, a gap is provided between the common conductive land and the contact resistance generating plate, and when a force or pressure is applied to push the contact resistance generating plate toward the conductive land, Depending on the magnitude and direction of the force or the pressure distribution, the small protrusions are crushed and the contact area between the contact resistance generating plate and the conductive land increases, so the contact resistance decreases. Along with this, the resistance between the common conductive land and the conductive land is reduced, and the force detecting device is characterized. 2. A conductive surface formed of two or more conductive lands formed on a substrate or a film and a non-conductive rubber or elastomer having a large number of microscopic protrusions on at least one side. Of 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 the contact resistance generating plate to be electrically connected. , A gap is provided between the surface of the contact resistance generating plate on which the minute protrusions are formed and the conductive land, and a potential difference is provided between the common conductive land and the contact resistance generating plate so that the contact resistance generating plate faces the conductive land. When a force or pressure that pushes in is applied, the minute protrusions 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 and the conductive land is large. The force detecting device is characterized in that the contact resistance becomes smaller by increasing the contact resistance, and the resistance between the common conductive land and the conductive land becomes smaller accordingly. 3. Four conductive lands are arranged at 90 ° intervals, and a change in four contact resistances generated between the conductive lands and the contact resistance generating plate acts on the contact resistance generating plate. The force detection device according to claim 1 or 2, wherein the magnitudes of the forces in the X-axis direction and the Y-axis direction and the directions or pressure distributions are detected. 4. Eight conductive lands are arranged at an interval of 45 °, and a change in eight contact resistances generated between the conductive lands and the contact resistance generating plate acts on the contact resistance generating plate. The force detection device according to claim 1 or 2, wherein the magnitude of the force in the eight directions and the direction or pressure distribution are detected. 5. Two conductive lands are arranged at an interval of 180 °, and a change in two contact resistances generated between the conductive lands and the contact resistance generating plate acts on the contact resistance generating plate. The force detection device according to claim 1 or 2, 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 protrusions formed on the contact resistance generating plate are in constant contact with the conductive land group.