US2320884A - Reflector system for lighting units - Google Patents

Description

INVENTOR w. A. PENNOW REFLECTOR SYSTEM FOR LIGHTING UNITS Fil ed May 6, 1941 Julie 1, 1943.

WITNESSES:-

Patented June 1, 1943 UNITED STATES PATENT OFFICE REFLECTOR SYSTEM FOR LIGHTING UNITS Willis A. Pennow, Cleveland, Ohio, assignor to Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa., a corporation of Pennsylvania Application May 6, 1941, Serial No. 392,029

2 Claims.

These and other objects of my invention will become more apparent from the following detailed description when read in conjunction with the drawing in which the single flgure is a partially sectionalized view in elevation of a searchlight embodying the principal features of my invention.

The invention is being disclosed in a practical form suitable for application to searchlights and covered, however, that while these reflector systhe like, although it is to be understood that it tems function as intended in some respects, their has application wherever a tandem reflector sysuse often results in exceptionally short lamp life tem is utilized, whether it be in a floodlight, due to blistering, softening or devitrification of searchlight or some other type of lighting unit the glass envelope or bulb of the lamp caused by employing a light source in the form of an incanthe inherently misdirected light rays of the sysdescent or other lamp having a glass or othertem. This results from the fact that the spheriwise destructible envelope which may become cal reflector is located immediately in front of damaged or impaired by abnormal light energy and on the opposite side of the lamp from the concentration thereon.

main reflector, so that the light rays reflected Referring to the drawing, there is shown a preback onto the spherical reflector from an area 0 ferred embodiment of my invention as it may at the central part of the main reflector, i. e., be applied to a searchlight of well known conthe misdirected rays, are reflected by the spheristruction. The searchlight comprises, generally, cal reflector in a concentrated manner onto the a body or drum Ill having a front opening which side of the bulb adjacent the spherical reflector. is closed by a door ll comprising a door ring This results in a concentration of destructive l2 hinged to the drum and a glass lens Hi. The heat energy on the bulb. drum l0 may be mounted for movement in both I have discovered that this disadvantage may elevation and azimuth in a well known manner be overcome and the destructive eflects of the on the bow M which is only partially shown for misdirected light rays eliminated or appreciably the sake of simplicity. reduced, by masking off those rays which cause The searchlight is provided with an incandamage W h t in ny way affec ing or reducing descent lamp l5 supported by the socket Hi from the useful light output of the reflector system. the lamp adjuster I! mounted at the bottom of The object of my invention, generally stated, the drum as shown, is to provide a reflector system for a searchlight, Th Searchlight is further provided with a or the like, which shall be of simple and ecotandem reflector system comprising, a main or nomical construction and which shall function primary reflector l8 and an auxiliary reflector l9. o p du th maximum light pu W t ut The main reflector l8 may be of any suitable damage to the glass envelope of the light source. type h, for x l as a polished and 11.

A more Specific Object Of my invention is to vered glass reflector supported at the back of provide for substantially reducing the amount the drum by means of it m clips 2|, T i of intensity of the misdirected light in reflector may be of a parabolic or elliptical shape a tandem TefieFtOT System; or any other suitable shape.

A ar h oblect of my mventlon 15 F provlde The spherical reflector l9 may be composed of utlhzmg a tartdem ltefiector syspem m Search aluminum having a reflecting surface. It may hghts, and the hketwlthout causmg damage to be supported in any suitable manner, such, for the envelope of the light source through the con- 1 b m n f the bracket 22 and centration thereon of misdirected light energy. f as y ea t h h Another object of the invention is to provide Spider the bracket 2 belng ac ed to 6 for masking 011 by means of an opaque shield, lamp ad uster IT as shown. If desired, the spidor otherwise, a predetermined area o t main er 23 also may be utilized to support alouver 24. reflector of a tandem reflector system to subpomtefi out h l P y 9 Stantiauy eliminate or reduce the heating up f Ject of my nvention 1s to prov1de for reducing the glass envelope of the light source used theree a t e clestructlve effects of the with due to the concentration of misdirected light directed l1ght r ys 1n a reflector system of thls rays thereon. 55 type, In order that the energy from these l1ght rays will not be concentrated upon the surface of the lamp bulb.

As will be readily understood, all of the light rays from the lamp 15, such as may be illustrated by the dash line A, are projected as useful rays A2 through the front door of the searchlight drum. The rays Al which strike the spherical reflector l9 are reflected back through the filament or light source zone of the lamp and are added to the useful light rays A2.

It will be further understood, however, that all of the light rays, such, for example, as those illustrated by the dash line B, and which fall upon the main reflector IS in an area represented by the lines X and Y, are projected back onto the spherical reflector H! as rays B2 and are reflected by it as rays B3 onto the surface of the f bulb l5. All of therays B, B2 and B3, are the misdirected light rays of the system and are those rays which cause damage to the lamp bulb.

In order to eliminate the destructive effect of these rays, I have provided for masking them off from the main reflector or rendering them ineffective. This result may be effected in a number of different ways. However, in this instance it is accomplished by means of an opaque shield suitably attached to the face of the main reflector i8 by means of the machine screw 26, nuts 21, and washers 28. This shield is preferably made of an opaque or non-reflecting material which absorbs or fails to reflect any of the light rays B which are projected upon it from the filament zone of the lamp. Itshould be of such diameter as to effectively intercept all of the rays B. When the shield is mounted in the position shown closely adjacent to the face of the main reflector, it is substantially of the same diameter or configuration as that of the spherical reflector l9. It will be readily understood, how: ever, that this shield may be positioned at almost any point between the main reflector and the lamp l5, and that its diameter will vary accordingly.

While I have shown the use of an opoque shield for accomplishing the desired result, it will be apparent that this result may be accomplished in other ways. For example, the main reflector l8 may be provided with an opening of suitable size, or the reflecting surface of the reflector may be omitted or removed over a predetermined area which is equivalent to that covered by the shield. In addition, this area on the face of the reflector might be covered with heat or light absorbing material. Likewise, the shield 25 may be composed of heat or light absorbing material. In fact, the desired results may be accomplished by any means which functions to block off from the main reflector all of these rays from the light source which, when reflected by it, will fall upon the spherical reflector I9.

In view of the foregoing description, it will be apparent that my invention provides for readily and economically improving the operation of a tandem reflector system without in any way impairing or reducing the efficiency of the lighting unit in which it may be used. By utilizing the principles of my invention, the tandem reflector system may be used with all its attendant advantages without the disadvantage of reduced life of the lamp resulting from the destructive heating effects of the misdirected light rays of the system.

Since it is apparent that various changes and modifications may be made in the illustrated example of my invention without departing from the principles thereof, it is intended that all matter contained herein shall be considered as illustrative and that the invention shall be limited only by the scope of the appended claims.

I claim as my invention:

1. A lighting unit comprising, a housing having a front opening, a transparent cover for said opening, a main bowl-shaped reflector mounted in the back of the housing opposite the front opening, an incandescent lamp, means including a socket for supporting the lamp in the housing in front of the main reflector with its axis at right angles to the axis of the main reflector and the light source region on the focal point of the main reflector, an auxiliary spherical refiec tor of lesser diameter than the main reflector and spaced from the lamp and supported within the housing on the opposite side of the lamp directly facing the main reflector with its axis coinciding with the axis of the main reflector and its center point in the light source region of the lamp, and an opaque nonreflecting circular shield supported from the main reflector intermediate the said reflector and light source directly opposite the spherical reflector, saidshield having an eifective diameter of such magnitude as to mask off an area on the main reflector to prevent any light rays from the lamp being reflected from the main reflector into the spherical reflector for re-reflection onto the glass envelope of the lamp adjacent the spherical reflector, thereby to prevent damage to the glass envelope by concentrated heating.

2. A lighting unit as defined in claim 1, wherein said auxiliary spherical reflector is supported from the lamp supporting means, and said circular shield is supported by means positioned in an opening in the main reflector.

WILLIS A. PENNOW.

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