US1731712A - Watch crystal - Google Patents

Description

Oct. 15, 1929. P. B. DAVIS 1,731,712

WATCH CRYSTAL Filed Dec. 29, 1926 INVENTOR.

A TTORNEYS.

Patented Oct. 15, 1929 UNITED STATES PRIDHAM B. DAVIS, 01 LOS ANGELES, CALIFORNIA WATCH CRYSTAL Application filed December 29, 1926. Serial No. 157,839.

This invention relates to articles of manufacture, and particularly to watch crystals of the non-breakable type. The average socalled non-breakable watch crystal is unsat isfactory in various particulars, the most notable of which is that the crystal under pressure will contact with the hands or face of the watch.

My invention has for an object the provision of a non-breakable crystal which tends to greatly resist deformation.

Another object is the provision of a crystal which is inexpensive, easy to manufacture, and generally superior in use and service.

As best illustratin the invention, I have provided a sheet of drawing in which Figure 1 is a plan view of a wrist watch embodying the invention;

Figs. 2 and 3 are plan views of crystals of different contour embodying the invention;

Figure 4 is a cross section of the crystal shown in Fig. 2 and showing the effect of pressure thereon; and,

Figure 5 is a perspective view of the crystal shown in Figure 2.

Corresponding parts in all the figures are designated by the same reference characters.

Referring to the drawing the improved article of manufacture in its several forms is designated as an entirety by A and B and in Fig. 1 I have shown my improved article of manufacture in combination with a watch C. In particular the so-called unbreakable crystals are usually formed of some transparent material such as celluloid, and in the present instance I take the celluloid and form the same by a die in such a manner that the resultant piece will assume a pyramidal form, as illustrated in Figs. 2, 4 and 5. It is important to note that the top zone 1 does not reach what may be termed a pointed apex. In other words, the respective sides 2 forming the pyramid merge together adjacent the top 1 to provide a curved or domed portion. This is best illustrated in Fig. 5. The division between the faces 2 is reasonably well defined, and while the faces may be comparatively fiat, yet it is within the purview of the inven tion to have the outer surfaces slightly convex. The outline or rim portion of the crystal may assume any contour desired, depending upon the bezel of the watch. For instance, in Fig. 1 the bezel 3 of the watch C is substantially square and the crystal A would fit within said bezel. If pressure were applied on the Zone 1 the crystal would tend to move directly outwardly in all directions, as illustrated in Figure 4. However, if this crystal were placed within the bezel 3, the bezel would so confine the crystal that pres sure upon the part 1 would not tend to deform the crystal unless the bezel was broken. In the so-called round or convex-concave watch crystals pressure upon the center of the crystal will cause such crystal to collapse downwardly against the face of the watch or its hands, the expansion, due to such collap sion forcing the crystal upwardly around the central depressed portion, and often allowing the crystal to escape from its bezel. It is very evident upon inspection of the drawing that this would be practically impossible of accomplishment with the present invention.

In Figure 3, I provide a crystal B which retains all the features of my invention in that it is of pyramidal form, the outline, however, being slightly different in order that such a crystal may be applied to a different shaped bezel of a watch. As before, the pyramidal faces 4 and 5 are provided, the faces 5 being larger than the faces 4. These faces all merge into a rounded or curved apex 6. This crystal would tend to resist stress the same as the crystal A.

This invention also contemplates the combination with a crystal of the bezel member which tends to aid the crystal in resisting deformation, such as illustrated in Figure 4. This bezel constitutes a reinforcement.

It is obvious that various changes and modifications may be made in practicing the invention, in departure from the particular showing of the drawing, without departing from the true spirit of the invention.

Having thus disclosed my invention, I claim and desire to secure by Letters Patent:

1. As a new article of manufacture, apyramidal watch crystal formed of unbreakable material.

2. As a new article of manufacture, a Watch crystal formed of unbreakable material and having a plurality of joined triangular faces merging in a curved apex.

3. As a new article of manufacture, a Watch crystal formed of unbreakable material and having angularly related face portions. 7

In testimony whereof, I have signed my name to this specification.

PRIDHAM B. DAVIS.

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