JPS6117089B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a switch mechanism, and more particularly to a switch mechanism using pressurized conductive rubber as an opening/closing member.

Pressurized conductive rubber is a recently developed material that differs from conventionally provided conductive rubber in its properties as follows.

In other words, conductive rubber is made by mixing carbon powder into the rubber to lower its own electrical resistance. Similarly, the switch is configured to turn on and off by mechanically bringing the conductive rubber into and out of contact with the electrically conductive terminal.

On the other hand, the pressurized conductive rubber is made by mixing special metal particles into silicone rubber, and under normal conditions has a large electrical resistance of several tens of MΩ, similar to that of an insulator. When a light pressure is applied in one direction, the electrical resistance in the vicinity of that pressure direction is
As shown in FIG. 2, it has the property of rapidly decreasing and changing into a conductor of several tens of ohms.

Therefore, by skillfully utilizing the properties of this pressurized conductive rubber, it is possible to construct a switch with a light force and an extremely short operating stroke.

Next, an example of a switch mechanism that has already been proposed using the above-mentioned pressurized conductive rubber as a member for opening and closing a switch will be explained with reference to FIG. In this switch mechanism, a plate-shaped pressurized conductive rubber 1 is placed on a pattern of conductive terminals 3a and 3b printed in parallel on a printed circuit board 2, and on this pressurized conductive rubber 1, A switch button 4 for pressing the pressurized conductive rubber is provided.

The conductive terminals 3a, 3b are formed by a conductive pattern in which two strips of conductive foil are printed in parallel on the substrate 2, and each conductive terminal 3a, 3b is connected to its outer end by soldering or the like. They are connected to appropriate electric circuits through lead wires 5a and 5b, respectively. Then, the conductive terminal 3
The pressurized conductive rubber 1 is placed on a and 3b so as to simultaneously cover these parallel portions, and the switch button 4 is disposed in contact with the upper surface of the pressurized conductive rubber 1.

In the switch configured in this way, when the pressurized conductive rubber 1 is pressed with the switch button 4, the electrical resistance of the pressurized rubber portion rapidly decreases and becomes conductive. Both conductive terminals 3a, 3b that are in contact with the portion are electrically connected. When the switch button 4 is released from the press, the conductive rubber 1 returns to an electrical insulator as described above, and the connection between the conductive terminals 3a and 3b is severed.

However, the existing switch mechanism configured as described above has the following drawbacks. That is, in order to electrically connect both the conductive terminals 3a and 3b well, the pressure of the pressurized conductive rubber 1 at the portion straddling the terminals 3a and 3b must be equalized to reduce the resistance of the pressurized conductive rubber. It is necessary to reduce the value uniformly, but in order to do this, the area to which the pressing force must be applied is quite wide, so a large pressing force is required, and in order to improve the conduction sensitivity, Although the distance between the two conductive terminals 3a and 3b must be made as narrow as possible, there are limits to this in terms of workmanship.

An object of the present invention is to solve the above drawbacks of the existing switch mechanism by folding a flexible printed circuit board having two conductive terminals into two, sandwiching a plate-shaped pressurized conductive rubber between them, and folding the flexible printed circuit board into two. To provide a switch mechanism using a pressurized conductive rubber, in which the pressurized conductive rubber is brought into a conductive state by pressing one of the upper and lower outer surfaces of a flexible printed circuit board, thereby making both conductive terminals conductive. It is in.

According to the present invention, simply by lightly pressing the pressing member, the pressurized conductive rubber is pressurized via the conductive terminal formed on the flexible printed circuit board, so that the switch can be reliably brought into conduction. The structure is extremely simple, and the operability of the switch can be greatly improved.

The present invention will be explained below based on an illustrated embodiment. As shown in FIGS. 3 to 5, the main parts of this switch mechanism include a plate-shaped pressurized conductive rubber 6 and two conductive terminals 8a and 8b formed in a printed pattern symmetrically on the left and right. A flexible printed circuit board 7 that is folded in half from the center and holds the pressurized conductive rubber 6; and a pressurizing force reinforcing plate 9 that is placed below the board 7 and has a plurality of protrusions 12 on its upper surface. , a pressing member 10 disposed above the substrate 7 and pressing the substrate 7 from above;
It is composed of mounting screws 11 that pass through the pressurized conductive rubber 6, the flexible printed circuit board 7, and the pressurizing force reinforcing plate 9, respectively, and screw these to the mounting plate 13. The pressurized conductive rubber 6 is formed into a flat plate having a rectangular planar shape. When the flexible substrate 7 is folded in half, its planar shape is approximately the same as that of the pressurized conductive rubber 6, and the open state is shown in FIG.

That is, a notch 14 is provided at one side edge of the central portion in the longitudinal direction so that the board 7 can be easily bent. A connecting portion 15 extending perpendicularly to the main body (not shown) of the board 7 is formed on the printed circuit board of the main body of the board 7 that is connected to the connecting portion 15. An electrical circuit that opens and closes is formed using a printed pattern. On the upper surface of the substrate 7c on the right side of the notch 14 of the substrate 7, one conductive terminal 8a having a size covering almost the entire surface is formed with a printed pattern, and one end thereof is placed on the connecting portion 15. It extends to form a conductive path that connects to the electrical circuit on the board body.
Further, on the upper surface of the substrate 7d on the left side of the notch 14, there is the other conductive terminal 8 having a size that covers almost the entire surface.
b is formed of a printed pattern, one end of which extends above the connecting portion 15 to form a conductive path connected to the electrical circuit of the board body, similar to the one conductive terminal 8a. Further, both the conductive terminals 8a, 8
The surfaces of the printed pattern b that come into contact with the pressurized conductive rubber 6 are each plated with gold to improve conductive efficiency. The pressurizing force reinforcing plate 9 is formed of a metal plate having approximately the same area as the pressurizing conductive rubber 6, and a metal plate is formed on the upper surface of the plate by punching from the lower surface.
A plurality of protrusions 12 having the same shape are provided.
This protrusion 12 is designed to particularly strongly press the portion of the pressurized conductive rubber 6 held by the substrate 7 that corresponds to the protrusion 12 when the upper surface of the flexible substrate 7 folded in half is pressed by the pressing member 10. It serves to pressurize, reliably reduce the electrical resistance of that part, and greatly improve conduction sensitivity.

The pressing member 10 is formed in the same manner as a normal push button, and is attached so as to be able to be pushed into the exterior plate 16 (see Fig. 5) of the device to which this switch mechanism is attached. Board 16
It is arranged so that it is almost flush with the surface of. Further, its lower end surface is arranged so as to be in contact with the upper surface of the flexible substrate 7. Further, the pressurized conductive rubber 6, the substrate 7 and the reinforcing plate 9 have through holes 6a and 7 through which the mounting screws 11 are inserted, respectively.
a, 7b, and 9a are drilled. And the fifth
As shown in the figure, the flexible printed circuit board 7 is folded in half, the two conductive terminals 8a and 8b on each inner surface are opposed to each other, and these are brought into contact with the upper and lower surfaces of the pressurized conductive rubber 6. After sandwiching the pressurized conductive rubber 6 by the substrate 7 and arranging the pressurizing force reinforcing plate 9 below it, the mounting screw 11
These are fixed to the mounting plate 13 by.

In this switch mechanism configured in this way, when the upper surface of the pressing member 10 is pressed, pressing force is applied from above and below to the flexible substrate 7 by the pressing member 10, so that the pressing force is applied to the flexible substrate 7 from above and below. The conductive rubber 6 is pressurized from above and below, and the electrical resistance of the pressurized conductive rubber 6 rapidly decreases, causing both conductive terminals 8a,
8b and turn on the switch. At this time, as described above, the pressing force reinforcing plate 9 greatly improves the conduction effect by its protrusion 12, so that even if the pressing force applied to the pressing member 10 is a weak force, both the conductive terminals 8a, 8b It is possible to ensure conduction between the two, and to perform an extremely efficient switching action.

FIG. 6 shows two conductive terminals 8a and 8b formed in a printed pattern on the flexible printed circuit board 7 shown in FIG. This shows another example in which the two conductive terminals 18a and 18b are printed on the boards 7c and 7d on the left and right sides of the substrate 7, as shown in the figure, in the following manner. Ru. That is, one conductive terminal 18a
are formed of conductive terminals 19a and 20a, which are formed in a comb-like shape and branch out in directions perpendicular to each other, and are printed on both substrates 7c and 7d, respectively.
The other conductive terminal 18b is similarly formed into a comb-teeth shape, and its free end is intertwined with the terminals 19a and 20a, branching out at right angles to each other and printed on the substrates 7c and 7d, respectively. It is formed of conductive terminals 19b and 20b. Further, the surfaces of both conductive terminals 18a and 18b are also plated with gold to improve conductive efficiency. When the pressurized conductive rubber 6 (see FIG. 3) is held between the conductive terminals 18a and 18b formed in this way, the conductive terminals 19a and 19b and the conductive terminals 20a and 20b are separated from each other in a plane. By intersecting each other in a mesh pattern in the vertical direction, when pressure is applied to the pressurized conductive rubber 6 and the conductive state is established, the conductivity in the thickness direction and the surface of the pressurized conductive rubber 6 allows the adjacent Since the patterns between the two are also conductive, it is possible to turn on the switch with even weaker force. This conduction effect, together with the pressurizing effect of the protruding portion 12 of the pressurizing force reinforcing plate 9 shown in FIG. 3, allows the pressing force to be reduced accordingly. In addition, the protrusion part 12 for sensitivity improvement may be provided in the part of the lower surface of the press member 10 which contacts the upper surface of the printed circuit board 7d.

As explained above, according to the present invention, the drawbacks of conventional switches of this type are successfully solved, and
It is possible to provide a switch mechanism with an extremely simple structure and greatly improved operability.

[Brief explanation of the drawing]

FIG. 1 is an exploded perspective view of essential parts of an existing switch mechanism using pressurized conductive rubber, FIG. 2 is a characteristic diagram of pressurized conductive rubber, and FIG. FIG. 4 is an exploded perspective view showing the configuration of a switch mechanism using piezoconductive rubber. FIG. 4 is an exploded perspective view of a conductive terminal in the switch mechanism shown in FIG. 3 above. FIG. 5 is an exploded perspective view of the switch mechanism shown in FIG. A cross-sectional view taken along line -A, and FIG. 6 is a developed perspective view showing another example of the conductive terminal. 1, 6... Pressurized conductive rubber, 7... Flexible printed circuit board, 8a, 8b, 18a, 18b...
...Conductive terminal, 10...Press member, 19a, 19
b, 20a, 20b... comb-shaped conductive terminals.

Claims (1)

[Scope of Claims] 1. Fold a flexible printed circuit board on which two conductive terminals are formed in a printed pattern in half from the center with the conductive terminal pattern facing inside and both patterns facing each other; A plate-shaped pressurized conductive rubber is sandwiched between both conductive terminal patterns by the bent substrate, and a pressing member is provided on one of the upper and lower outer surfaces of the printed circuit board, and the other has a protruding portion on the printed circuit board side. The pressurized conductive rubber is characterized in that a pressurizing force reinforcing plate is provided respectively, and by pressing the pressing member, the pressurized conductive rubber is pressurized to be in a conductive state, and the two conductive terminals are electrically connected. Switch mechanism. 2 The printed patterns of the two conductive terminals are formed in a comb-teeth shape, and when the flexible printed circuit board is folded in half, both patterns intersect with each other in the vertical direction. A switch mechanism using the pressurized conductive rubber according to item 1.