Metal working – Means to assemble or disassemble – Puller or pusher means – contained force multiplying operator
Patent
1990-01-16
1992-08-25
Oberleitner, Robert J.
Metal working
Means to assemble or disassemble
Puller or pusher means, contained force multiplying operator
29509, 267161, B21F 3500, F16F 134, B21D 3900
Patent
active
051407337
DESCRIPTION:
BRIEF SUMMARY
FIELD OF INVENTION
The present invention relates to a coned disc spring having a uniform deflectability over the entire periphery thereof, and specifically a coned disc spring made mainly of a steel plate, stainless plate, rubber plate or plastic plate and suitable for use as a diaphragm or a return spring for a key top of a keyboard switch.
The present invention also relates to the use of the such a cone-shaped disc spring as a diaphragm or a return spring for a key top of a keyboard switch, and to a pressure detector using the diaphragm, and to a method for mounting the diaphragm on a support member.
BACKGROUND ART
One prior art coned disc spring for use as a diaphragm is shown in FIG. 19 which is made of a plate-shaped material and has a circular central portion 10 and its peripheral portion corrugated to form rings P with a wave-shaped cross-section. The wave rings P in the drawings indicate the troughs of the corrugations (to be so understood hereinafter).
However, since this article Dc has its peripheral fixing portion subjected to brazing or the like, it has a high rigidity at this portion. Also it has a high rigidity at its central portion because the radius of curvature is small at this portion. Thus it is less liable to deflect at its peripheral and central portions. As a result, the deflecting force tends to concentrate on the intermediate portion thereof. This will increase the possibility of buckling and cracking owing to metal fatigue if the plate is made of a metal and also the characteristics, specifically the restoring force, of the plate can change during long use.
Typical keyboard switch structures are shown in FIGS. 16-18, but with the cone-shaped spring of the present invention therein. The one shown in FIG. 16 has a contact 42 on the inner bottom surface of a keyboard case 41. If a conventional disk-shaped spring is provided above the contact 42, as a key top 43 is depressed, the spring, which is connected to the key top 43 through a stem 44, will deflect downwards, thus actuating the contact 42. The key top 43 will be returned to its original position by the restoring force of the spring D. It is also known to form part of the contact 42 from the spring D if the spring has conductivity. The key switch shown in FIG. 17 has a coil spring 46 interposed between the keytop 43 and the stem 44 to improve the depressibility. The key switch shown in FIG. 18 has a lever 45 interposed between the disc shaped spring and the stem 44. The abovementioned depressibility refers to the relationship between the depth of depression of the key and the depressing force exerted by a fingertip.
Such conventional disc-shaped spring as used in the above-described switches has an ordinary flat pressure-receiving surface (contact surface with the stem 44). No modifications thereto have been proposed. Their deflectability and restorability after having been deflected depend largely on the properties of their material.
But such an improvement-by-material approach is not only reaching its limit but is also costly.
Also, the keytop 43 is not always depressed at the center of its top surface. A skilled operator who can type at a high speed tends to press the keytop at its corner portion. This has the following effect. By depressing the keytop at its corner, the depressing force is divided into a vertical component and a horizontal component, thus deflecting the spring D with both component forces. This may improve the operability.
But if the spring has a flat pressure-receiving surface, it will offer resistance to the horizontal component but will not deflect. Thus the operability is not good.
If a coned disc spring is used as a diaphragm, it is a common practice to use two annular flanges 22 to grip it therebetween from both sides along its edge, like the flanges 22 as shown on the disc D of the present invention in FIGS. 8(a) and (b).
The flanges 22 are bonded to the edge of the coned disc spring by means of an epoxy or silicone adhesive or by soldering at low temperature (190.degree. to 210.degree. C.).
But w
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Motokawa Shigeaki
Ohgashi Shinichi
Onishi Kihachi
Shimada Toshinori
Oberleitner Robert J.
Tatsuta Electric Wire & Cable Co., Ltd.
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