JP2001043772A - Push-button switching device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a push-button switching device that can prevent the occurrence of abrasion powder and provides a stable switching operation. SOLUTION: A cover member 6, in which a plunger portion 14 projecting downward to its bottom surface, is formed and a key top portion 12 is connected to a base portion 11 through a skirt portion 13, a click sheet 10, a buffer conductive sheet 16, and a circuit board 1 including a fixed contact 2 formed on the surface are mounted in this order. The buffer conductive sheet 16 is made of conductive elastomer, and preferably has 50-300 μm thickness, 0.1-10 Ωcm specific volume resistance, and 20-75 degrees in Shore A hardness. In the buffer conductive sheet 16, conductive fibers are formed in a state, in which they are directed in the thickness direction of an insulating resin layer, and at least part of the conductive fibers is exposed from the surface of the insulating resin layer, or a plurality of conductive cylinders filled densely with conductive particles are formed in a state in which they are directed in the thickness direction of the insulating resin layer, and the conductive cylinders are exposed from the surface of the insulating resin layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pushbutton switch device used for a data input device or a switch device of a mobile communication device such as a portable telephone, a switch of a vehicle-mounted device, and more specifically, an ON timing and a voltage drop value. The present invention relates to a push-button switch device that improves switching characteristics such as securing, suppressing bounce and chattering, and the like.

[0002]

2. Description of the Related Art In mobile phones and the like, a push button switch device is used as a data input device. FIG. 5 is a schematic sectional view of a main part of a conventional push button switch device. As shown in FIG. 5A, this push button switch device
Then, a metal disc spring 3 is fixed on a spacer film 7 with a fixing film 8 via a (conventional) click sheet 9 or, as shown in FIG.
Resin dome 4 with movable contact 5 on spacer film 7
The cover member 6 is assembled via a click sheet 9 formed by joining a fixed film 8 having Window holes 15 are formed in the spacer film 7 with the adhesive in correspondence with the fixed contacts 2. A conductive portion made of conductive ink or the like is provided as a movable contact 5 on the lower surface of the resin dome 4.

A cover member 6 has a plurality of key top portions 12 provided at positions corresponding to the fixed contacts 2 on a base portion 11 which is a support portion for the circuit board 1, through a thin skirt portion 13. The key top portion 12
Has a protruding plunger portion 14 on the bottom side. In such a push button switch device, when the top surface of the key top portion 12 is pressed, the plunger portion 14
, The key top portion 12 deforms the skirt portion 13 of the dome and is displaced toward the circuit board 1,
The central portion of the dome is deformed toward the circuit board 1 by the pressing force of the plunger portion 14, and the central portion of the dome comes into contact with the fixed contact 2, and the movable contact 5 inside the metal disc spring 3 or the resin dome 4.
As a result, the fixed contact 2 is closed. The resilient deformation characteristics of the metal disc spring 3 or the resin dome 4 in the click sheet 9 provide a repulsive force to the operation of the key top portion 12, that is, a click feeling.

In the conventional push button switch device, the movable contact 5 formed on the metal disc spring 3 of the click sheet 9 or the lower surface of the resin dome 4 directly contacts the fixed contact 2 made of metal. Abrasion powder is generated, and this conductive abrasion powder causes a short circuit between the other conductive patterns on the circuit board. In addition, the metal disc spring 3 of the click sheet 9 or the movable contact 5 on the lower surface of the resin dome 4 and the fixed contact There is a problem that the contact is likely to be a point contact, bounce, chattering, and the like occur, and the switching operation (ON, OFF) in a low / low current region tends to be unstable. In particular, in recent years, downsizing of devices and ASIC (Appl.
In addition, the above-mentioned problems are notable because rigidity-type substrates capable of forming a multilayer structure are frequently used, as the density of the circuit boards has been increased due to the progress of communication specific integrated circuits). A solution was strongly desired.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide a push button switch device capable of preventing generation of wear powder and obtaining a stable switching operation. I do.

[0006]

According to the present invention, there is provided a cover member in which a key top portion having a plunger portion projecting downward from a bottom surface and a base portion are connected by a skirt portion. , A click sheet, a conductive sheet for buffering, and a circuit board having fixed contacts formed on its surface are assembled in this order. The buffering conductive sheet is made of a conductive elastomer, has a thickness of 50 to 300 μm, a volume resistivity of 0.1 to 10 Ωcm, and 20 to
It is preferably made of a material having a Shore A hardness of 75 degrees.
The buffering conductive sheet is formed in such a manner that the conductive fibers are oriented in the thickness direction of the insulating resin layer, and at least a part of the conductive fibers is exposed from the surface of the insulating resin layer, or A plurality of conductive cylinders densely filled with conductive particles are formed so as to be oriented in the thickness direction of the insulating resin layer, and the conductive cylinder is exposed from the surface of the insulating resin layer.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION According to the present invention, by interposing a conductive sheet for buffering, contact between a metal and a movable contact made of a conductive ink and a metal can be avoided, and generation of conductive wear powder can be reduced. Based on the finding that it can be avoided. Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The push button switch device of the present invention includes a circuit board 1 having a fixed contact 2 formed on a surface thereof, a click sheet 10 provided thereon, and a cover member 6 provided thereon. A conductive sheet 16 for buffering is provided (FIGS. 1 to 3).

[0008] Depending on the mode of the click sheet 10, the present invention can be divided into three types. The first type uses a metal disc spring 3 (FIG. 1). The second type uses a resin dome 4 (FIG. 2). The third type does not use a dome-shaped object (FIG. 3). The circuit board 1 (FIGS. 1 to 3) of the present invention is made of glass epoxy, paper phenol, a rigid type board having a conductive pattern formed on these composite boards, or polyethylene terephthalate (PE), as in the prior art.
T), a flexible substrate in which a conductive pattern is formed on a film such as polyethylene naphthalate (PEN) or polyimide can be used.

On the surface of the circuit board 1, a plurality of pairs (fixed contacts 2) of fixed contacts 2 are provided. As the conductive material of the fixed contact 2, a metal such as copper, gold or nickel is mainly used, and in some cases, a conductive material made of resin may be used. A first type of click sheet 10 (FIG. 1) of the present invention is provided on a spacer film 7 having a window hole 15.
The opening edge of the dome of the metal disc spring 3 is placed on the periphery of the window hole 15 of the spacer film 7, and the metal disc spring 3 is fixed with the fixing film 8. A seat 16 is provided.

[0010] A second type of click sheet 1 of the present invention
0 (FIG. 2) is a spacer film 7 having a window hole 15.
A fixed film 8 provided with a resin dome 4 at a position corresponding to the fixed contact 2 on the circuit board 1 is fixed thereon, and a buffering conductive sheet 16 is provided on the spacer film 7 side. A movable contact 5 is formed on the back surface of the resin dome 4. However, depending on the mode of the buffering conductive sheet 16 (described later), the movable contact 5 is not required. In the first and second types, the spring-like elastic deformation characteristics of the dome-shaped object cause
A click feeling occurs when the key top portion 12 is pressed down. At that time, the spacer film 7 amplifies the click feeling. A third type of click sheet 10 (FIG. 3) of the present invention comprises a spacer film 7. When the spacer film 7 has a required thickness, it functions as an actuator.

On one side of the buffering conductive sheet 16, dots of 0.1 to 0.3 mm in thickness or insulating spacers 19 are arranged in a grid using an insulating resin so that The conductive sheet 16 may be appropriately provided so as to be insulated from the conductive sheet 16 for use and bend only when pressed by the plunger portion 14 so as to be electrically connected to the fixed contact 2. The members constituting the click sheet 10 and the conductive sheet 16 for buffering will be described in further detail below. The metal disc spring 3 is formed by forming a conductive metal thin plate of 0.1 to 0.3 mm such as stainless steel or phosphor bronze into a dome shape (bowl shape).

The movable contact 5 provided on the lower surface of the resin dome 4 is preferably formed by printing using conductive ink or the like. Examples of the conductive ink include an ink in which carbon is contained in a binder such as an acryl-based or polyester-based binder. Examples of the material of the spacer film 7 include general plastic films such as PET and PEN. The fixing film 8 is made of PE
T film or PEN film (thickness 0.1-0.
3 mm) is used. As described above, in the second type, the resin dome 4 is usually formed on the fixed film 8 at a position corresponding to the fixed contact 2.

The conductive sheet 16 for buffering (FIGS. 1 to 3)
Is one of the features that characterize the present invention, and typical forms thereof are shown in FIGS. 4 (a) to 4 (d). That is,
(A) When the conductive linear body 17 is oriented in the insulating resin layer 18 in the thickness direction of the buffering conductive sheet 16, (b) one side of the buffering conductive sheet 16 made of the conductive rubber 20 is insulated. When the spacer 19 is provided, (c) the conductive particles (2
(1) When the conductive column 22 densely filled in the insulating resin layer (18) is oriented and arranged while being insulated by the insulating member 23, (d) the conductive particles 21 are
When they are dispersed and blended, any of them can be adopted.

At least a part of the conductive linear body 17 in FIG. 5A and the conductive columnar body 22 in FIG. 5C are exposed on the surface of the insulating resin layer 18. By exposing, the conductivity in the thickness direction of the buffering conductive sheet 16 is ensured. From the conductive sheet material for buffer formed in the elongated body, the conductive linear body 17 oriented in the insulating resin layer 18,
By cutting the conductive cylindrical body 22 at right angles to obtain the conductive sheet 16 for buffering, the exposure to the surface thereof is easily ensured. In the case of the conductive rubber 20 of (b), since the fixed contact 2 can be closed only by the buffering conductive sheet 16, it is necessary to use the metal disc spring 3 or the movable contact 5 on the lower surface of the resin dome 4. This has the advantage of eliminating. In this case, by using the spacer film 7 as an EL film or by the light guiding action of the base portion 11 and the skirt portion 13 of the cover member 6, the metal disc spring, which tends to be a problem when the key is illuminated, is conventionally used. 3
In addition, it is possible to avoid obstacles caused by illumination by the movable contacts 5.

In (c), the densely packed conductive cylinders 22 are arranged at a pitch of 0.5 to 1.0 mm, so that the pitch of the most common fixed contacts at present can be accommodated. As the material of the insulating resin layer 18 and the insulating member 23 used here, polyester, polyvinyl chloride, polymethyl methacrylate, polyolefin, polyamide, polycarbonate, thermoplastic resin such as polystyrene, unsaturated polyester, polyurethane, silicone, Thermosetting resins such as fluorine-based resins, and rubber-like elastic bodies such as natural rubber and various synthetic rubbers may be used. In particular, in consideration of workability, compression set, elastic properties, and the like, silicone rubber as a thermosetting resin is preferable. The materials of the insulating resin layer 18 and the insulating member 23 may be the same.

Examples of the conductive material kneaded in the insulating resin layer 18 include metals such as gold, copper, nickel, brass, phosphor bronze, aluminum and iron, and conductive materials such as these and glass bee resin and silica. Examples include powders and grains (fibrous, spherical, scale-like, irregular shapes) obtained by applying a non-conductive material to a conductive material, for example, metal plating such as nickel, gold, and silver. The filling of the conductive material is preferably performed in an amount of 100 to 800 parts by weight with respect to 100 parts by weight of the insulating resin. In the present push-button switch device, the buffering conductive sheet 16 is used under pressure and compression. However, when it is used for portable equipment, it is desirable to make the filling rate as high as possible, since it ensures electrical connection even if the pressing force is small.

The conductive linear body 17 which is a fibrous conductive material
When using, the conductive linear body 17 is mixed in an insulating resin material, and is sufficiently kneaded with a roll, an extruder or the like to form an oriented elongated body, and the elongated body is formed into a conductive linear body. The cushioning conductive sheet 1 is cut at right angles to the body 17.
6 is obtained. It is desirable that at least a part of the conductive linear body 17 be exposed from the surface of the buffering conductive sheet 16 by using a length longer than the thickness of the buffering conductive sheet. The mixing property when arranged or mixed in the insulating resin layer 18, the rigidity against bending stress and shear stress applied when cured and integrated, and the generation of conductive wear powder due to contact with the fixed contact 2. Considering prevention as much as possible and workability,
It is preferable to use a fibrous material containing metal fibers such as an alloy such as brass and phosphor bronze. A plurality of these metal fibers, thin metal wires, and conductive fibers may be bundled.

When powders, granules, etc. are used as the conductive material, the conductive particles 21 are uniformly and densely dispersed and mixed in the insulating resin layer 18 to form the conductive rubber 20 (FIG. 4).
(B)), the density of the conductive particles 21 is reduced to form an anisotropic conductive sheet in which only the pressing portion becomes conductive (FIG. 4D).
A conductive columnar body 22 in which conductive particles 21 are densely filled in an insulating resin layer 18 are oriented in the buffering conductive sheet 16 and arranged so as to be insulated from each other by an insulating member 23 ( FIG. 4C may be used. Buffering conductive sheet 16
Preferably has a thickness of 50 to 300 μm. If the thickness is less than 50 μm, the conductive resin may be peeled off or fall off, failing to function sufficiently as a conductive sheet. If the thickness exceeds 300 μm, the conductive material increases in the thickness direction, and the hardness increases. When the switching operation is performed, a large pressing force is required, which is not preferable as the switching function, and the manufacturing cost is increased.

The buffering conductive sheet 16 preferably has a Shore A hardness of 20 to 75 degrees. If the hardness is 20 degrees or less, the insulating resin layer becomes sticky and the click feeling becomes poor. If the hardness is 75 degrees or more, it is too hard and a large pressing force is required at the time of the switching operation. The switching operation due to pressing is impaired. As shown in FIGS. 1 and 2, by providing a light reflecting layer on the upper surface of the spacer film 7 or without using the light reflecting layer as a separate body, the fixing film 8 itself is made into a film having a white or metallic luster. Thus, in the case of key illumination, the spacer film 7, the base portion 11, the skirt portion 13, and the like can be efficiently used as a light guide, and the light can be efficiently used as a whole. Also, as shown in FIG.
When the conductive rubber 20 having conductivity is used, the metal disc spring 3 and the movable contact 5 on the back surface of the resin dome 4 do not need to be used. At the time of illumination, the cause of illumination unevenness such as shadows can be eliminated, so that there is an advantage that illumination unevenness is eliminated. Further, since the spacer film 7 or the fixing film 8 can be made to perform a light guiding action, the key top portion 12 has a small LE.
Even in the case of D or the like, the advantage of uniform illumination can be utilized.

The cover member 6 (FIGS. 1 to 3) includes a base portion 11 serving as a support portion for the circuit board 1, a plurality of key top portions 12 corresponding to the fixed contacts 2, and a thin skirt portion 13.
Are continuously formed so as to be relatively displaceable through the key top portion 1
2 has a plunger portion 14 protruding downward on the bottom surface. The key top section 12 and the plunger section 14 are connected to the circuit board 1.
It is provided at a position corresponding to the upper fixed contact 2. The cover member 6 includes a key top portion 12 and a base portion 1 formed of a thermosetting elastomer, particularly, silicone rubber.
1, a form composed of a plunger portion 14 and a skirt portion 13,
The key top portion 12 is a resin molded product, and the base portion 1
1. The plunger portion 14 and the skirt portion 13 are formed of silicone rubber, adhered and formed into a composite form, or formed into a key top shape by a film, and a thermosetting elastomer or a thermoplastic elastomer is formed in the formed film. Filled form, furthermore thermoplastic elastomer,
For example, there is a generally-known hinge key formed of a polycarbonate resin, an acrylic resin, an ABS resin, or the like.

FIG. 1 shows a push button switch device according to the present invention.
In the case of FIG. 2, pressing the top surface of the key top portion 12 causes the key top portion 12 to deform the skirt portion 13 and displace toward the circuit board 1, and the plunger portion 14 constitutes the click sheet 10. The top of the metal disc spring 3 or the resin dome 4 to be pressed is pressed, and the metal disc spring 3 or the resin dome 4 is pressed.
Is deformed toward the circuit board 1, and the center of the dome comes into contact with the fixed contact 2 via the buffering conductive sheet 16. In another embodiment of the push button switch device according to the present invention, that is, in the case of FIG. 3, the top surface of the key top portion 12 is pressed, and the plunger portion 14
The buffering conductive sheet 16 is pushed down through the contact, and the buffering conductive sheet 16 contacts the fixed contact 2 to make the fixed contact 2 conductive.

At this time, since the portion to be contacted to close the fixed contact 2 is the conductive sheet 16 for buffering, even when the metal disc spring 3 is used, Even when the movable contact 5 is provided, the metal does not directly contact each other, or the movable contact 5 made of printing ink does not directly contact the metal that is the fixed contact 2, so that generation of conductive wear powder is prevented. In addition, since the contact is made by the buffering conductive sheet 16, the fixed contact 2 is stably brought into surface contact, and bounce, chattering, and the like can be prevented. Furthermore, when the conductive rubber 20 is used for the buffering conductive sheet 16, it is not necessary to provide the movable contact 5 with conductive ink or the like on the lower surface of the resin dome 4. In addition to preventing the generation of abrasion powder from the conductive portion, which was difficult to perform, the cost of click sheet molding can be reduced.

[0023]

The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the invention is limited thereto. (Example 1) Conductive silicone rubber; 87C40PU
(Shin-Etsu Chemical Co., Ltd. product name)
A sheet having a thickness of 0.3 mm was formed. Using an insulating silicone TSE3331 (trade name, manufactured by Toshiba Silicone Co., Ltd.) on one side of this sheet, an insulating spacer 19 is dot-printed so as to avoid the fixed contact portion, and cut into a shape of a push button switch device for buffering. The conductive sheet 16 was obtained. At this time, the Shore A hardness of the buffer conductive sheet 16 is 60
Degree.

Using a transparent PET film having a thickness of 0.1 mm, the circuit electrode portion is dome-shaped in a convex shape to obtain a fixing film 8 including the resin dome 4 and fixed to the convex side of the resin dome 4. The spacer film 7 (transparent PET film having a thickness of 0.1 mm) from which the contact 2 was removed was adhered, and the above-mentioned conductive sheet 16 for buffering was also provided to obtain the click sheet 10. Next, the key top portion 12 is molded using a polycarbonate resin, and the base portion 11, the skirt portion 13, and the plunger portion 14 are formed of insulating silicone rubber KE-.
The cover member 6 was obtained by molding using 961 U (trade name, manufactured by Shin-Etsu Chemical Co., Ltd.) and bonding to the key top portion 12.

These are placed on an insulating spacer 1 on a circuit board 1.
The click sheet 10 and the cover member 6 were installed in this order such that 9 was on the circuit board 1 side, and a push button switch device was obtained.
This push button switch device has a click feeling when pressed by the click sheet, and furthermore, there is no adhesion of foreign substances such as dust and dust on the circuit board, and no conductive wear powder is generated, so that a short circuit of the circuit can be prevented, The buffering conductive sheet made stable contact with the fixed contact by surface contact, and excellent switching characteristics were obtained.

(Example 2) In Example 1, the spacer film 7 of the click sheet 10 was replaced with white P
An ET film was also used as a light reflection layer. Others were the same as Example 1. In this case, when an illuminated push button switch using an LED or the like is used, light from the LED or the like is reflected by the white PET film, and there is no light unevenness in the cover member 6 and the light is uniform, which is also preferable in design. No foreign matter such as dust and dust adheres, and no conductive abrasion powder is generated, so that short circuit of the circuit can be prevented. The conductive sheet for buffering makes stable contact with the fixed contact by surface contact, and excellent switching characteristics Was obtained.

(Example 3) Insulating silicone rubber KE-
961U (see above), key top part 12, base part 11,
A push-button switch device was obtained in the same manner as in Example 2, except that the cover member 6 was provided with a skirt portion 13 and a plunger portion 14. If this is also an illuminated push button switch using an LED or the like, the light from the LED or the like is reflected by the reflective film, and there is no light unevenness in the cover member, which is uniform and preferable in design. A push button with excellent switching characteristics, with no adhesion of foreign matter and no generation of conductive wear powder, which can prevent short-circuiting of the circuit and a stable contact with the fixed contact by surface contact with the buffering conductive sheet. It became a switch device.

(Example 4) Insulating silicone rubber KE-
171U (trade name, manufactured by Shin-Etsu Chemical Co., Ltd.) is blended with carbon fiber (fiber diameter 3 to 20 μm, length 1 to 3 mm),
Using a mixing roll and an extruder, a vulcanized molded block in which carbon fibers were oriented was obtained. The block was cut at a right angle to the carbon fiber orientation direction and had a thickness of 0.3
mm sheet was obtained. This sheet was cut into the shape of a push button switch device to obtain a conductive sheet 16 for buffering. In the conductive sheet for buffer 16, at least a part of the end of the carbon fiber is exposed from the surface of the conductive sheet for buffer 16. At this time, the Shore A hardness of the buffer conductive sheet 16 was 50 degrees.

A metal disc spring 3 made of a thin metal (0.1 mm thick beryllium copper) plate by press molding is used.
PE having a window hole 15 formed in the fixed contact 2 portion of the circuit board 1
The apex is placed upward on a spacer film 7 made of a T film (thickness 0.1 mm), and the periphery and the spacer film 7 are attached to a PE with an adhesive (acrylic).
It is held and fixed by a fixing film 8 made of a T film (thickness: 0.1 mm).
Click sheet 10 was obtained. The cover member 6 according to the first embodiment
The specifications were the same as above. A click button switch device was obtained by installing the click sheet 10 and the cover member 6 in this order on the circuit board 1 on which the fixed contacts 2 were provided in advance, with the top of the metal disc spring 3 facing upward. This push button switch device provides a high click feeling when pressed by the metal disc spring of the click sheet, and furthermore, there is no adhesion of foreign substances such as dust and dust on the circuit board, and no conductive wear powder is generated. Short-circuits could be prevented, and the conductive sheet for buffering stably contacted the fixed contact by surface contact, resulting in excellent switching characteristics.

Example 5 Instead of the carbon fiber of Example 4, a brass metal fiber (fiber diameter 30 μm, length 1-6 m)
m) to give a sheet having a thickness of 0.2 mm. This sheet was cut into a shape suitable for the push button switch device, to obtain a conductive sheet 16 for buffering. In the conductive sheet for buffer 16, at least a part of the end of the brass metal fiber is exposed from the surface of the conductive sheet for buffer 16. The click sheet 10 was the same as in Example 4.

The key top portion 12, the base portion 11, and the skirt portion 1 are made of insulating silicone rubber KE-961U (described above).
3. The cover member 6 having the plunger portion 14 was installed on the circuit board 1 with the top of the metal disc spring 3 facing upward, the click sheet 10 and the cover member 6 in that order to obtain a push button switch device. . This push button switch device provides a high click feeling when pressed by the metal disc spring of the click sheet, and furthermore, there is no adhesion of foreign substances such as dust and dust on the circuit board, and no conductive wear powder is generated. Short-circuits could be prevented, and the conductive sheet for buffering stably contacted the fixed contact by surface contact, resulting in excellent switching characteristics.

(Example 6) Insulating silicone rubber KE-
100 parts by weight of 171U (trade name, manufactured by Shin-Etsu Chemical Co., Ltd.) were mixed with 500 parts by weight of gold-plated conductive particles of nickel particles having an average particle diameter of 40 μm and molded. This molded product was formed into a cylindrical shape having a diameter of 0.5 mm, and arranged in the above-mentioned insulating silicone rubber KE-171U at a pitch of 1.0 mm to obtain a molded product. .
The conductive sheet 16 for buffer was obtained by slicing to 3 mm.
At this time, the Shore A hardness of the buffer conductive sheet 16 is:
55 degrees. The movable sheet 5 is provided inside the resin dome 4 of Example 1 with conductive ink containing carbon, and the click sheet 1 provided with the buffering conductive sheet 16 is provided.
0, the cover member 6 was incorporated into the circuit board 1 to obtain a push button switch device. This push button switch device has a high click feeling when pressed by the metal disc spring of the click sheet,
In addition, there is no adhesion of foreign substances such as dust and dust on the circuit board, and no conductive abrasion powder is generated, so that short-circuiting of the circuit can be prevented. Excellent switching characteristics were obtained.

[0033]

According to the present invention, since the buffering conductive sheet directly contacts the fixed contact, the wear of the contact and the like can be prevented, and the short circuit of the circuit due to the conductive wear powder can be prevented.
Stable surface contact is obtained, and stable and excellent switching characteristics in which bounce, chattering, and the like are prevented are obtained.

[Brief description of the drawings]

FIG. 1 is a schematic vertical sectional view of a main part of a push button switch device of the present invention.

FIG. 2 is a schematic vertical sectional view of a main part of another push button switch device of the present invention.

FIG. 3 is a schematic vertical sectional view of a main part of another push button switch device of the present invention.

FIG. 4 is a schematic cross-sectional view of a shock-absorbing conductive sheet of the push-button switch device of the present invention.
(B) is a diagram showing the case of conductive rubber, (c) is a diagram showing the case where the conductive particles are densely packed, and (d) is a diagram showing the case where the conductive particles are dispersed.

5A and 5B are schematic diagrams showing a conventional push button switch device, wherein FIG. 5A shows a case of a metal disc spring, and FIG. 5B shows a case of a resin dome.

[Explanation of symbols]

 1: circuit board 2: fixed contact 3: metal disc spring 4: resin dome 5: movable contact 6: cover member 7: spacer film 8: fixed film 9: (conventional) click sheet 10: (conventional) click sheet 11: Base 12: Key Top 13: Skirt 14: Plunger 15: Window Hole 16: Buffering Conductive Sheet 17: Conductive Wire 18: Insulating Resin Layer 19: Insulating Spacer 20: Conductive Rubber 21 : Conductive particles 22: conductive cylinder 23: insulating member

Claims (5)

[Claims] 1. A cover member in which a key top portion formed with a plunger portion projecting downward from a bottom surface and a base portion are connected to each other by a skirt portion, a click sheet, a buffer conductive sheet, and a fixed contact. And a circuit board formed in this order. 2. The push button switch according to claim 1, wherein the buffer conductive sheet is made of a conductive elastomer, has a thickness of 50 to 300 μm, and has a volume resistivity of 0.1 to 10 Ωcm. apparatus. 3. The push-button switch device according to claim 1, wherein the conductive elastomer has a Shore A hardness of 20 to 75 degrees. 4. The buffering conductive sheet is formed in such a manner that conductive fibers are oriented in a thickness direction of the insulating resin layer, and at least a part of the conductive fibers is exposed from a surface of the insulating resin layer. The push-button switch device according to claim 1, wherein: 5. The buffering conductive sheet is formed such that a plurality of conductive cylinders densely filled with conductive particles are oriented in a thickness direction of the insulating resin layer. 4. The push button switch device according to claim 1, wherein the conductive column is exposed from the surface of the push button switch.