Switching construction for a handy electronic device

#This invention relates to the switching construction for an electronic device specially designed for increasing the reliability of the water proof characteristics of the input switch portion by the employment of electro conductive rubber for the water proof packing member.

#It is possible to make a portable and handy electronic device, for example an electronic calculator, due to the remarkable development of the electronic technic especially the integrated circuit and the manufacturing technic for the display device whereby it is possible to combine the electronic calculator in a wristwatch.

#It is very useful to construct the calculator and the digital electronic wristwatch in one casing as one body, however, such a combination creates new problems. Namely it is necessary to have severe water proof characteristics for the wristwatch, and it is necessary to provide many input switches for the calculator, however, it is not preferable for the water proof characteristics to provide many switches for the wristwatch, because it is necessary to provide many through holes to the casing of the wristwatch.

#FIG. 1 shows a flat plan view of a wristwatch-calculator assembly according to the present invention,

#FIG. 2 shows a cross-sectional view thereof,

#FIG. 3 shows an enlarged cross-sectional view of the switching section shown in FIG. 2, and

#FIG. 1 shows the flat plan view of the electronic device equipped with an electronic calculator, for example, a wristwatch 1 having the electronic calculator. Said wristwatch 1 is composed of a glass panel 2, the casing 3 mounted on a electronic circuit 7 of the watch being disposed in the inner cavity defined by said glass 2 and casing 3. A set of externally-actuatable operating members 4 are mounted to said casing 3, and a digital display device 5 composed of a plurality of display elements 5a is disposed beneath the glass panel 2. Said set of external or outer operating members 4 is composed of a switching member 4a for switching the electronic circuit and the display contents to the desired function, for example the watch function or the calculating function, and a series key switches 4b for operating the input signals for using the electronic calculator. The water proof characteristics are especially needed for the switching members disposed in a flat shaped construction as indicated in FIG. 1.

#FIG. 2 shows the cross sectional view of II--II line in FIG. 1. The printed circuit board 6 is electrically connected to the electronic circuitry 7 and the display device 5 is mounted in a recess portion of the casing body 3a of the casing 3 and an electro conductive rubber member 9 is mounted on said printed circuit board 6 via an insulating member 8. The glass member 2 comprises a glass portion 2a and a glass bezel 2b mounted to said casing 3, the cover member 3b having a plurality of depressable key switches 4b mounted thereon. A spring member 3c in the form of a ring is attached to the side channel portion of the casing body 3a thereby completing the assemblage. A small battery 7a as the power source is housed in a battery housing portion which is closed by a cover member 7b threaded to the casing body 3a.

#FIG. 3 is the enlarged partial cross sectional view for explaining the detailed construction. It is possible to completely separate and seal the region between the interior of the casing body 3a which houses the electronic circuit 7 and display device 5 and the casing exterior by said electro conductive rubber member 9 which is mounted and retained in place by the printed circuit board 6 and projecting portions A and B of the cover member 3b via said insulating member 8. Namely, the gap area between said glass bezel 2b and said cover member 3b is completely sealed by the pressing force exerted on the rubber member 9 by the cover member portion A and the gap area between said casing body 3a and said cover member 3b is completely sealed by the pressing force exerted on the rubber member by the cover member portion B. An E-shaped ring member 4c functions as the stopper for each key switch 4b and is very useful in achieving the water proof effect.