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.

In the conventional type of wristwatch-calculator assembly, the water proof characteristics for sealing the switches in the wristwatch comprises a generally ring shaped rubber packing member associated with each switch. However it is not so preferable to employ said rubber packing member for said switches from the standpoint of cost and from the standpoint of overall wristwatch size. Further the reliability of the wristwatch becomes lower by the need for many water proof portions.

This invention aims to eliminate the above noted difficulty of the water proof construction in the switching portion of the conventional type wristwatch-calculator assembly and therefore the principle object of the present invention is to provide a common electrode composed of electro-conductive rubber sheet for the switches as the water proof packing member.

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. 4 shows a flat plan view of another embodiment of wristwatch-calculator assembly according to the present invention.

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.

Referring now to the operation of the present invention:

Upon depression of said key switches 4b, said electro conductive rubber member 9 is flexed into contact with the printed conductor 6a on the printed circuit board 6 via the hole portion 8a formed in the insulating member 8 whereby the ON and OFF operations are attained. Therefore, said electro conductive rubber member 9 assumes a plus potential via the route of the plus side of the battery, the battery cover 7b, the case body 3a and the cover member 3b whereby the plus-potential is applied to the preferable printed conductor 6a by the pushing operation of said key switch 4b. Said key switches are positioned in accordance with the requirements of the calculating circuit and the time counting circuit, and are disposed under the display device 5 at equal intervals as indicated in FIG. 1. Further it is possible to dispose the key switches in a circular shape as indicated in FIG. 4.

According to the present invention, the water proofness of the electronic device having many switches is attained by the use of the electro conductive rubber member functioning as the common electrode and the water proof packing member whereby it is possible to attain the high reliability and the lower cost for the wristwatch having the calculating function.