US821306A - Prismatic reflector. - Google Patents

Description

No. 821,306. PATENTED MAY 22, 1906.

' 0. A. MYGATT.

PRISMATIG REFLECTOR. APPLICATION nun) nn0.14,1so3.

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No. 821,306. 'PATENTED MAY 22, 1906. I.

0. A. MYGATT.

PRISM ATIG REFLECTOR. APPLICATION FILED 530.14.1003. I

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attozmug ITED STATES PATENT OFFICE.

one A. MYdZFLTBFiIEW YORK, N. Y.

I PRISMAATIC REFLECTOR.

Patented May- 22, 1906.

Application filel December 14, 1903. Serial No. 185,125.

To all whom it may concern: 7

Be it known that I, QTIs A. MYGATT, a citizen of the United States, residing at New York, in the county of New York and State of New York, have invented certain new and useful Improvements in Prismatic Reflectors,

the-prismatic surface modified by the omission of parts of the reflecting-prisms, the por-,

tions from the reflecting-prisms which are omitted permitting the passage of light. Where the reflecting-prisms are omitted, the outer surface of. the reflector may have lightdirecting facets, so that the light-'rayswhiclr ,pass through the glassare directed in determined directions.

As I have explained in my Patent No.

' 736,535, of August 18, 1903, the most complete reflection oflight-rays by a prismatic-glass reflector is accomplished when the light-rays from within the reflector encounter the outer planes of the prisms at angles of forty five degrees. As artificial lights are most frequently arranged to throw the light-rays downwardly, I will for convenience describe my reflector with reference to such an arrangement; but

of course this arrangement may be varied.

In thedrawings, Figure 1 is a diagram illustrating an incandescent lamp, a prismatic refiector, and the course of some light-rays. Fig. 2 is a detached perspective view of a reflecting-prism, showing direction of reflected light-ray. Fig. 3 is a similar View of an in- 'terrupted prism. Fig. 4 is a front view of such a prism. Figs. 5 and 6 are perspective views of interrupted prisms, showing course of some light-rays. Fig. 7 is a side elevation of a reflector embodying a modification of the invention. -Fig. 8 is *a similar view of another modification, and Fig. 9 still another modification.

A prismatic-glass reflector of roper form externally covered with prisms o the character shown in Fig. 2 is capable under favorable circumstances of reflecting as much as eightyfive per cent. of the light-rays which reach the prisms'fromwithin the reflector. The most effective reflecting-prisms are arranged I radially. A spiral arrangement of prisms,

such as disclosed by me in" former patents, can be used, but is less effective.

illuminating outside the reflector.

By mutilating or removing parts of some of the prisms light-rays will be permitted to pass through the reflector at these parts, thus By forming the outer surface of these parts of the reflector into light transmitting and directing facets or prisms instead of light returning .or reflecting prisms the light-rays which pass through the reflector will be (llI'BCiLBCl or distributed as desired. Such external illumination will be of course at the expense of the device asa complete reflector.

- In Fig. 1 let the section A represent a frusto-conical body externally provided with reflecting-prisms 1. As seen from the viewpoint A the reflector appears dark. This is because the light rays have been mainly refl'eoted back by prisms 1 in the general direction indicated by lines a b c or a b c. The small percentage of light which passes through or between prisms 1 continues upward in the direction a 11 Now if a prism 1 be interrupted or modified for part of its length and the outer face of the reflector which would be otherwise occupied by such" prism l be cut up into approximately horizontal' planes 2, arranged so that light from within the reflector shall strike these planes at suchan angle that such light shall not be reflected'back into the reflector, the rays will,

pass through and will thence be directed by the planes 2. The lines a c as, a c x indicate directions such rays may take. At the angle illustrated in Fig. 1 surfaces 3 are substantially inert. It is apparent that by arrang-' ing the surfaces 2 in such planes as to direct the light-rays according to known 0 tical laws the rays which pass through the re ector can be either concentrated ordiflused. The transverse prisms produced by the mutilation of prisms 1 may have several sides, so as to have one or more directing, one or more refracting, and the necessary neutral surfaces. (See Fig. 5 and see patent of Blondel et cZ., No. 563,836, for explanation of such prisms.) In Fig. 1 the lines 0 w, indicating light-rays, are parallel, While in Figs. 6 and 7 the lines 0 x converge and reach a focus at a distance depending on the inclination of surfaces 2.

In Figs. 4, 5, and 6 the horizontal surfaces 2 on the vertical prisms 1 are of various sizes. Of course alarge surface 2 will permit the passage of more li ht-rays. than a smaller one. In Fig. 9 these ight-directing surfaces form bands extendingaround the reflector. The

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surfaces 2 may thus. be made to appear as bright bands or as rows 01 bright bead-like brllhants, or they may e. made to represent.

characters. Thus in Fig. 8 thelctter M is 5 shown composed of triangular hght-transnnt-Il ting facets. The side of the reflector so constructed will of course have a very dill'ercnt tion and improwrment. By the present invention I may take transmitted llght-rays flom any part of the reflector-body and may take more or ess such rays from one side or the other. The distribution, therefore, of both transmitted and reflected rays may be very unequal.

Highly-ornamental decorative effects may be produced by the present invention, as well as' more complete control of the lightrays. By permitting more or less light-rays to pass througl ihe reflector almost any distribution of light may be ell'ected without changing the form of the reflector-body.

What I claim is 1. A reflector composed of a single piece of glass inform of a frustum and having an open mouth, the outer surface having approximately vertical reflecting-prisms by which light-rays are returned and directed out at the open month, said reflecting-prisms inter:

E rupted in parts in definite patterns, whereby l l l l l l l glass having on its outer surface rel definite portions of light, from definite parts of the-Teflector-body, are permitted to pass throu h the reflector. a

2. g reflector composed of a single piece of glass, having its outer surface provided with reflectimyprisms with their axes extending in 1 a generally vertical or radial direction, some i of said prisms mutilated by the lntroduct'lon therein of plane'surfaces calculated to transmit and direct light-rays.

3. A reflector composed of a sin le iece of glass and having its body in form oi a rustum with an open mouth, and having on its outer surface refieetingprisr.is arranged to return light-rays from within the reflector back and out at said mouth, certain of said prisms varied in parts by surfae es arranged to transmit light-rays through the reflector and to direct the rays after passage 4. A reflector comp )sed of a single )iece of lectingrisms, certain of said prisms being mutilated )y the in troduction of light-transmitting surfaces varying in size. I

In testimony whereof I aflix my signature in presence of two witnesses.

O'llS A. MYGA'IT. Witnesses:

W. A. Doaar, Gno. A. (o'rl\.

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