JP2000132307A - Keyboard switch - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent additional costs from being required for adhesive assembly with a rubber sheet-shaped object for forming a key top part by applying the device of a little shape working to the sheet-shaped object and a polyethylene terephthalate(PET) dome switch while using not a silicone rubber but a thermoplastic polyester elastomer composition for the material of the sheet-shaped object. SOLUTION: Not the silicone rubber but the composition mainly composed of thermoplastic polyester elastomer is used. A sheet-shaped object 6 integrating a depressing part 3 composed of thermoplastic polyester elastomer, deformable part 4 and base part 5 or the like PET dome switch 10 and a PET dome switch 10 located on the downside are combined by inserting plural projections 16 of diameter shorter than 2 mm belonging to the sheet-shaped object 6 to plural holes 17 provided in the PET dome switch. Thus, complicated work such as adhesive sticking can be omitted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a switch and a keyboard switch.

[0002]

2. Description of the Related Art A remote control used for TVs, audios, and earphones, and a keyboard switch (an aggregate of a plurality of push-button switches and push-button switches in telephones, pagers, personal computers, and other countless fields). Hereinafter, KBSW) is used. The present invention relates to a KBSW mainly used for a mobile communication device such as a mobile phone and a PHS.

A push button switch has a spring mechanism. One uses a metal string spring, and is used for personal computer keyboards that require low pressing force and low click feeling. Further, KBSW made of silicone rubber is often used for TV remote controllers and the like. This is a silicone rubber integrated product, and the role of the spring is performed by the silicone rubber itself. The PET dome switch is a KBSW formed by forming and combining a sheet made of polyethylene terephthalate resin (hereinafter, PET). FIG. 1 shows a top sectional view of a mobile phone using a PET dome switch, which will be described below. Here, (1) is an upper case, (2) is a resin key top, and (6) is a rubber sheet supporting the key top, which is usually made of silicone rubber. (10) is a PET dome switch, and (11) is a switch substrate. PET dome switch (10)
Consists of two or more PET sheets bonded with an adhesive,
The upper sheet (7) has a substantially spherical shape formed by hot press molding. When the key top (2) is pressed, the force is transmitted to the vertex of the spherical portion of the PET dome switch (7) and dents with the pen, and returns to the original state when the force is released. The role of the spring is PE
T himself is doing. A similar example using a metal tact switch is shown in FIG. Here, the metal tact switch is (1
As shown in 4), this is made of a thin metal plate and has the same basic structure as the PET dome switch, and the role of the spring is performed by the thin metal plate.

[0004] Except for a personal computer keyboard or the like, a push button type switch usually has a high click feeling and 150 to 30 degrees.
A pressing pressure of about 0 g is required. The click feeling is a feeling that the switch is turned ON. The order in which the click feeling is easy to give is the order of material hardness, metal sheet, PE
The order is T sheet and silicone rubber. At present, from the viewpoint of what plays a role of a spring as a KBSW of a mobile phone or the like, silicone rubber which is too soft is not used, and a metal tact switch and a PET dome switch are used. Actually, a metal tact switch has been used for a long time, since a high click feeling can be obtained with a short stroke. The phone industry was arbitrarily determined to think that mobile phones would prefer short strokes and high clicks. Therefore, the manufacturing cost of the PET dome switch was lower than that of the PET dome switch.

[0005]

However, inexpensive P
The ET Dome SW is also being chased by metal tact switches. One is that the keying durability, which is a weak point of the metal tact switch, has been improved, and an excellent assembling method has been developed with the metal tact switch, and the cost difference has been reduced in total cost. FIG. 1 shows a top sectional view of a mobile phone using a PET dome switch, and FIG. 2 shows a top sectional view when a metal tact switch is used. In FIG. 1, the key top (2) is at the top, and then a sheet material (6) made of silicone rubber is provided.
0), and further below there is a switch substrate (11). Actually, the key top (2) and the sheet-like object (6) are bonded in advance at the sheet pressing part (3) and are integrated. The integrated product of the key top and the sheet-like material is further bonded to the PET dome SW (10) with an adhesive, and the whole is usually treated as one part of the KBSW.

[0006] On the other hand, in FIG.
A metal tact switch (14) fixed to a switch substrate (15) with an adhesive tape (13) is provided underneath. FIG.
This figure shows a case where it is assembled by a method which is regarded as an assembling method of a product using a metal tact switch which is currently the cheapest.
As a work order, a hole positioned in advance on the adhesive tape is made, and the head of the metal tact switch is made to penetrate the hole so that the hem portion is adhered. The adhesive tape with the metal tact switch is attached to the switch substrate (15) while positioning. Explaining the flow including division of labor,
The metal tact switch maker makes a hole in the adhesive tape according to the ordering instruction drawing, attaches the metal tact switch to make an adhesive tape with the metal tact switch, pastes release paper, and sells it to a telephone assembly company or a board manufacturing company.
These work processes can be relatively easily automated and the packaging and transportation are easy, so the cost UP is small. Also, it is not so difficult to attach an adhesive tape with a metal tact switch to a switch substrate performed by a telephone assembly company. In recent years, the performance of pressure-sensitive adhesives has increased and has become more reliable.

As described above, the cost advantage of the PET dome switch has been reduced by the development of a rational assembling method of the metal tact switch. So, to counter this, PE
We studied the cost reduction when using a T-dome switch. This will be described with reference to FIG. Looking at this assembled structure,
Since the sheet-like material (6) and the PET dome switch (10) are sandwiched and fixed between the case (1) and the switch substrate (11), there is no need to inherently bond and integrate them. However, actually, it is adhered as described above to form KBSW as an integrated part. The sticking process is a silicone rubber sheet (6)
Screen printing with adhesive ink on the back side of PE
Attach the T-dome switch (10) or use a double-sided adhesive on the top of the PET dome switch (10).
A method of further attaching an ET sheet, attaching the ET sheet to a sheet-like material, and integrating the ET sheet and the like is adopted, and all of these methods are considerably costly. This is done because it is convenient to treat KBSW as an integral part, but it should be further streamlined.

[0008]

According to the present invention, as shown in FIG. 4, a pressing portion (3), a deformable portion (4) and a base portion (5) made of a composition mainly composed of a thermoplastic polyester elastomer. ) Etc. and the PET dome switch (10) located thereunder by a plurality of protrusions (1) having a diameter of 2 mm or less belonging to the sheet-like material (6).
6) provided in a plurality of holes (1) provided in the PET dome switch.
7) A keyboard switch characterized in that it is integrated by plugging in 7) to perform its function.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 3, 4, 5, and 6 are schematic cross-sectional views of a KBSW according to the present invention and a case where the KBSW is incorporated. The present invention will be described in detail with reference to these. (10) in the figure is a PET dome switch.
The hole (17) having a diameter of about 2 mm or less is preferably square or rectangular, and may be circular. In addition to the holes, there may be cuts on the left and right. (6) in the figure is a sheet-like material made of a thermoplastic polyester elastomer composition. It has a diameter of about 2mm or less and a length of 0.5 to
A projection (16) of about 1 mm is provided. The projection is preferably cylindrical. At least two of these projections / holes,
Usually four to five locations are provided. Specific KB on mobile phones, etc.
In the design of the SW, there is almost no margin in place, so the place is selected not only in the four corners. Even if there is a place, the diameter of the projection / hole, or the long diameter imitating a circle when the projection or hole is not circular, is often forced to be about 1 mm or less. However, if the diameter of the projection is set to 0.5 mm or less, it is weak and practically difficult to assemble. The diameter is preferably 0.5-2 mm, more preferably 0.7-2 mm.

[0010] In the actual production, making a hole in the PET dome switch is only required to modify the punching die in such a manner, and there is no problem at all. On the other hand, the molded article of the thermoplastic polyester elastomer composition may be formed by providing a cylindrical or prismatic concave portion at a predetermined position of a mold, but when it is actually formed, burns are apt to occur due to a blind path. Therefore, it is also effective to use a sintered metal locally in the mold.

The present invention has been found to work with the use of thermoplastic polyester elastomers. The reason why using a silicone rubber molded article instead of a thermoplastic polyester elastomer composition molded article does not work is that the former (thermoplastic polyester elastomer type) has good dimensional stability and small fluctuation in the distance between a plurality of protrusions. In the latter, the dimensional fluctuation is large, and in the former, the hardness is not so low as in the latter, and the work of pushing the projection into the hole is easy. Even when the KBSW according to the present invention made of a thermoplastic polyester elastomer composition was transported in a stacked manner, there were no accidents such as the projections and holes coming off and falling apart, and the projections being rubbed off. In contrast, a silicone rubber sheet and a PET dome switch
When the KBSW produced by combining the holes was packed / transported, there were KBSWs in which the projections came out of the holes and became loose. Silicone rubber is the most flexible among rubbers, but also has high slipperiness. It was easy to slip out if there was a misalignment, but the good slippage seemed to backfire.

The thermoplastic polyester elastomer composition used in the present invention will be specifically described. The composition may be composed mainly of a thermoplastic polyester elastomer commercially available from many manufacturers, and the thermoplastic polyester elastomer may be as it is, but it may be an unvulcanized rubber, a plasticizer, a crystallization nucleating agent, a pigment, Dyes and other additives may be contained.

A commercially available thermoplastic polyester elastomer is a block polymer in which hard segments composed of polytetramethylene terephthalate (polybutylene terephthalate, PBT) and soft segments composed of polymethylene glycol are alternately bonded.
In particular, a multi-block polymer in which the soft segment is polytetramethylene glycol and the hard segment and the soft segment are alternately connected can be more preferably used. Unvulcanized rubber and a plasticizer can also be added, and these can adjust the composition hardness to a lower one. Further, by adding a crystallization nucleating agent, a thermoplastic polyester elastomer which is originally opaque can be made transparent. As other auxiliaries, there are a mold release accelerator added to facilitate the mold release during molding and an antioxidant to suppress oxidation at a high temperature.

Next, differences between FIGS. 3, 4, 5, and 6 will be described. FIG. 4 shows a case where the sheet-like material (6) is the cheapest KBSW and has no resin key top and also serves as the key top. If display printing is required, it is performed on the upper surface. FIG. 3 shows a case in which the resin key top (2) and the sheet material (6) are separately molded and bonded. If the key top is made of a transparent resin, the display print can be printed on the back surface of the key top, and the display does not disappear even if the surface of the key top is worn. Recently, KBSW by two-color molding or insert molding of a transparent resin and a thermoplastic polyester elastomer has been put on the market. FIG. 5 shows an example in which this technique is used. By performing display printing and special printing on the back surface of the key top (2), inserting the thermoplastic polyester elastomer composition into a mold and injecting the thermoplastic polyester elastomer composition, a sheet-like material (6) of the key top (2) and the thermoplastic polyester elastomer composition is obtained. ) Is obtained by injection bonding. The other structure is the same as the case of FIG. FIG. 6 shows a sheet-like object (6) and a PET dome switch (10).
The projections / holes are changed in how they are attached. Here is a case that does not bother the switch board design. Projection (16)
Is placed in the recessed position of the sheet-like material base portion (5), and a hole (17) is provided in the center portion formed in a dome shape also on one PET dome switch side. As a result, the holes shown in FIG. 4, for example, the holes (18) in FIG.
I don't need something like In mobile phones and the like, weight reduction and miniaturization are required, and boards are crowded with circuits. KBSW
In order to rationalize several tens of yen, there are many cases where the useable area on the substrate is lost by tens of square millimeters.

Hereinafter, specific examples of the present invention will be described, but the present invention is not limited to these examples. <Example> After preparing a PET sheet having a thickness of 0.10 mm and conducting conductive printing and printing, the sheet was heated to 110 ° C. and pressed with a press die, and a spherical projection having a diameter of 3 mm in a plan view as shown in FIG. (Vertex height 0.5 mm, sphere radius 20 mm) and diameter 2
A PET sheet having six mmφ conductive contacts was obtained. A 0.1 mm thick PET sheet with an adhesive and release paper is punched out with a press-cutting mold, and the release paper is peeled off to form the preformed P.
The spacer was attached to the ET sheet. This 2
The sheet on which the PET sheets are adhered is further punched out with a press die, the outer periphery is cut to make the whole rectangular, and a square hole of 0.9 mm square is formed near two corners.
A 0.9 mm × 1 mm rectangular hole was punched in the corner.
This was designated as a PET dome switch, (10) in FIG.

Next, a thermoplastic polyester elastomer composition was prepared. 82 parts by weight of thermoplastic polyester elastomer "PIBIFLEX35M" (manufactured by Enikem Pomeri), 2 parts by weight of acrylonitrile butadiene rubber "JSR / NBR" (manufactured by JSR), and 0.8 part by weight of a crystallization nucleating agent specified by the manufacturer And silicone oil "Silicone oil SH (manufactured by Toray Dow Corning)"
After mixing with 0.05 parts by weight using a Henschel mixer, the mixture was kneaded with a twin-screw extruder under the conditions of a heating temperature of 200 ° C. and a screw rotation speed of 150 RPM. DUP
(Manufactured by Shin Nippon Rika Co., Ltd.) was added to prepare a thermoplastic polyester elastomer composition. J of this
The ISA hardness was 86 degrees. In addition, "PIBIFLE
X35M "is a multi-block polymer in which a plurality of PBT hard segments and polytetramethylene glycol soft segments are alternately connected, and has a molecular weight of 1,000.
00-150,000, softening point 175 ° C, melting point 192 ° C,
It has a JISA hardness of 93 degrees.

A sheet-like material (6) shown in FIG. 4 was obtained by injection molding using the above-mentioned thermoplastic polyester elastomer composition. Here, the deformable part (4) has a thickness of 0.12.
It was in the form of a thin film having a thickness of about 0.14 mm and a width of 0.7 mm and a standing angle of 30 degrees, and was formed in a skirt shape surrounding the key pressing portion (3). The number of keys was 6 in two rows of three, and the keys were elliptical with a major axis of 10 mm and a minor axis of 8 mm when viewed in a plan view. The whole sheet is rectangular in plan view, and the projections (16) are provided on the back surfaces of the four corners. The mold was made on the assumption that the protrusion had a cylindrical diameter of 1 mm and a length of 0.7 mm (specifically, a frusto-conical shape with a draft angle of 3 degrees). The key arrangement and the position of the projection (16) are of course matched with the positions of the spherical projections and holes of the PET dome SW. In manufacturing the mold, the molding shrinkage of the thermoplastic polyester elastomer composition was set to 15/1000. The protrusion (16) of the actually obtained molded product had a root diameter of 0.98 mm and a height of 0.67 mm.

The above-mentioned PET dome switch (10) and the sheet-like object (6) were aligned, and projections corresponding to four holes were inserted. The protrusion (16) could be easily pushed into the square hole (17) of PET, and once inserted, it did not come off easily and did not fall apart. This was designated as KBSW. Assuming the handling of packing, transportation and telephone assembly, I loaded it in a shipping box and made two round trips between Tokyo and Kyushu by courier, but it was well tolerated.

The KBSW was assembled with the case (1) and the switch board (11) as shown in FIG. 1mm thick
In the switch board (11), a hole (18) shown in FIG.
A hole having a diameter of 1.2 mm was provided so that the KBSW protrusion did not interfere with the horizontal setting on the substrate. The key was pressed. There was a good click feeling unique to the PET dome switch, and it could be used without any problem without any abnormal noise.

[0020]

The PET dome switch itself can be adapted to a complicated switch arrangement and is inexpensive. However, in actual use, an extra cost is required for assembling with a rubber-based sheet material forming a key top portion. In the present invention, the above-mentioned extra cost can be eliminated by using a thermoplastic polyester elastomer composition instead of silicone rubber as the material of the sheet-like material, and adding a slight shaping process to the sheet-like material and the PET dome switch. . PE tactile tact switch assembly method has also been improved
Although the cost difference with the T dome switch is approaching and competition is intensifying, the present invention can further increase the cost competitiveness of the PET dome switch.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a conventional example of using a PET dome switch.

FIG. 2 is a schematic sectional view of an example of using a conventional metal tact switch.

FIG. 3 is a schematic sectional view of an example of using a KBSW of the present invention.

FIG. 4 is a schematic sectional view of a KBSW application example of the present invention.

FIG. 5 is a schematic sectional view of a KBSW application example of the present invention.

FIG. 6 is a schematic sectional view of a KBSW application example of the present invention.

[Explanation of symbols]

 (1) Upper case (2) Resin key top (3) Pressing part of sheet material (4) Deformable part of sheet material (5) Base part of sheet material (6) (7) Upper sheet of PET dome switch (8) Spacer of PET dome switch (9) Conductive contact (10) PET dome switch (11) Switch board (12) Comb electrode (13) Adhesion Tape (14) Metal tact switch (15) Switch board (16) Projection provided on sheet material (17) Hole provided in PET dome switch (18) Hole provided in switch board

Claims (1)

[Claims] An integrated sheet-like material (6) such as a pressing portion (3), a deformable portion (4) and a base portion (5) made of a composition mainly composed of a thermoplastic polyester elastomer, and PET located thereunder The dome switch (10) is connected to a plurality of projections (1
6) provided in a plurality of holes (1) provided in the PET dome switch.
A keyboard switch characterized in that the keyboard switch is integrated and functions when plugged into 7).