US1897364A - Spotlight - Google Patents

Description

Feb. 14, 1933. G, 13u-:TZ 1,897,364

SPOTLIGHT Filed Feb. 10, 1930 VZ/u2 i L Patented Feb. 14, 1933 UNITED STATES PATENT oFFicE GUSTAV DIETZ, OF WEST HOLLYWOOD, CALIFORNIA, ASSIGNOR F ONE-HALF ,To

SPOTLIGHT Application led February 10, 1930. Serial No. 427,187.

This invention has to do with spot lights, or spot lamps, such as are ordinarily used in the illumination of sets in motion picture photography, and is more particularly related to reflectors, such as are used in spot lights of this character, having as its primary object the production of such a reflector, wherein the reflecting surface is composed of metal and is of a character such that it does -lo not affect the light beam during its expansion or contraction with changing'temperatures. It is well known to those familiar with the artthat the usual type of spot light embodying eitheran incandescent lamp or an arc associated with a lens or merely with a reflector,

if brought to a perfect focus, projects an image of the filament or the arc upon the focal plane. Such images are very'undesirable in photographic work and for this reason the light source is usually positioned out of focus to destroy the image of the filament. By arranging the light source in this manner, the beam projected by the reflector contains a series of dark spots or light and dark rings which produce shadows and make'the proper illumination of theset and the actors thereon extremely difficult.

The type of reflector ordinarily used in lamps of this character is `a properly shaped 3o silvered glass mirror, since the high temperatures encountered in lamps of this character will cause warpage in the ordinary metal refiectors, making them impractical for this use. It is an important object of this invention to produce a metal reflector which is so constructed that it may be subjected to anytem` perature without warping and consequently destroying the effectiveness of the light beam. This object is accomplished by making the refiecting surface as a series of angular plate segments mounted upon a suitable frame or support, each of the segments being secured at one end only so that the unsecured end may move back and forth with the expansion of the metal, thereby maintaining the same curvature in the plate under all temperature conditions.

It is a further object of this invention to produce `a reflector, ofthe class described,

which is designed so as to break up the light beam and prevent the formation of an image of the filament regardless of the position of the light source with respect to the reflector. This is accomplished by knurling the reflecting plates or segments mentioned above so x that they may be considered as consisting of a. plurality of flat, or substantially fiat, refiecting surfaces. I prefer to make thesesurfaces Vof a uniform width which is less than the width of the lamp filament. This con-i struction breaks up the image of the lamp filament, and prevents the formation of light and dark rings. In the use of a reflector of the type contemplated by this invention, it will be seen, therefore, that a uniformly dis-F65 tributed beam of light is produced which may be softened without showing light and dark rings or may be brought to a focus without showing an image of the filament in the focal plane.

The general construction of the reflector, contemplated by this invention, consists of a metal support or frame, preferably made in the form of a cage-like dome which consists of Va plurality of concentric ring members connected by radial arms. The reliecting plates mentioned above are attached to the ring members by means of pins or small screws, and I prefer to arrange these plates so that they are not in tight engagement with each other. This construction permits expansion ofthe plates and also facilitates the ventilation of the lamp.

With regard to the ventilation of the lamp, I I considerit a further object of this in-'85 vention to produce a reflector of the class described which is provided with Ventilating means preferably designed to draw air from within the enclosing drum, or body 'of the lamp,'through the passages between the re- '90 fleeting plates and to exhaust the same behind the reflector. This not only cools the reflector, maintaining a uniform and bright reflecting surface, but it also decreases the j temperature of the region in front ofthe lamp.

Details in the construction of a preferred form of my invention, together with other objects attending its production, will be bestd understood from the following description Fig. 3 is an enlarged sectional elevation.

which may be considered as having been taken in the plane represented by` the line 3 3 in Fig. 2.

More particularly describing the invention as herein illustrated, reference numeral 11 indicates a lamp of the class described which consists-of an enclosing drum or housing 12 anda reflectorl; the housing-containing a lightsource, shown as comprising an incand-escent lamp 13 which has a `filament 14. The

' rear portion of the housing 12 is shown as having mounted thereon, or formed integrali lytherewith, an annular reflector supporting vflange 15 which supportsV the reflector throughthe medium of a plurality of i vbrackets generally indicated by reference nu-` meral' 17. Reference numeral 18 indicates a yVentilating fan which will be hereinafter more fully described.

The reflector 15 is shown as embodying a cage-like dome andis made up of a plurality of'con'centric supporting rings 19,19, 19h,k

735 and 19, connected by means of a plurality 'of= Nvradial arms 20. This frame or support is preferably made as an aluminum casting and the arins 2O are all connected at their midsupport may 46 point with a hub member 21, their outer ends being connected to the outer ring 19. lThe into zones, the hub 21 and rings 19 and 19a comprising one Zone while the rings 19a, 19" and'19c comprise another zone. The refleeting surface, generally indicated. by reference numeral 22, consists of a pair of'V corresponding reflecting zones each formed by a plurality of vmetal reflecting 5d plates 22a and 22b respectively. These plates are made in the form of angular segments,

^ which are secured at one end only upon the frame member by means of pins' or screws.

It will be noted, in Fig. '3, that the ring member 19a is provided with an inwardly projecting shoulder 2lagainstr which the outer ends of the reflecting segments 22LV are held in pressure engagement by means of small pinsor screws indicated b-y reference numeral 25. The inner ends of the segments 22a are held against outward movementby means of a plate or disk 2G, which is retained uponthe h ub member 21'by means of a screw 27, and is spaced a slight 'distance away from the hub member by means of vthe washer 28. The space provided between the disk 27 and bel described as being formedl the inner surface of the Ahub 21 permits the free longitudinal expansion of the segments 22a. The ring member 19 provides a supporting surface which, during the expansion of the segments 22a, provides a support for the mid-section of such segments, maintaining thereby a uniform reflecting surface throughout the entire area or zone formed by the segments 22", It will be noted that theouter ends'of the members 22a extend a slightl distance beyond the pins 25, and the shoulder 24 holds these end portions slightly above a ledge or shoulder 30 formed on the .outer periphery ofthe ring member 19a, so as to leave a space between the segments 22a and 4the ring` member 19a, such space being adapted to receive the inner end portions of the seg- Vments 22. .The space mentioned above is sufficient to permit the free longitudinal moveinentof the ends of the segments 22D, and

the'outer ends of these segments are secured to theV frame -or support by means of screws or pins 31, which are positioned in the outer ring member 19C. The outer ring member 19C is provided'with a ledgeor shoulder 32,'

which is engaged by the segments 22", and is adapted to assist in holding the segments in position while the reflector is being assembled.

In order that the segments may be guided during their longitudinal expansion, I pro- Y vide the outer segments 22b at their mid-por` `tions with elongated notches 33, such notches being adapted to receive pins 33', which are driven or otherwise secured in the ring members 19h. It will 'be noted, from Fig. 2, that the inner end portions of the segments 22b are of a width such that the inner ends of two of these segments are positioned beneath the outer end of one of the segments 22a. It

- will also be noted that the inner end portionsv of the segments 221 are cut away, as indicated by reference numeral 34,so that the cut-away portions of twoadjacent segments are, opposite the securing pins 25, which hold the outer ends of the inner segments 22a to the support. This construction permits the free longitudinal expansion of the outer segments 22b without interference from the securing pins 25.

Itwill be observed from the constructionV so far described, that the reflecting segments 22n and 22"- are of a floatingnatnre; in other words, these segments are secured at only one end, andare free to move longitudinally during their natural expansionl or contraction with the changing temperature; during such movement there is no warpage or distortion in-the reflecting surface. This construction,y

therefore, permits the manufacture of an allmetal reflector, which has a uniform reflecting surface under all temperature conditions; the plates may be easily and quickly replaced in the event they are damaged in any way; and

'the segments are preferably arranged so that there is a small space between adjacent seg-` ments, which permits the ventilation ofthe lamp by means ofthe fanl8, the'details of the construction ofwhichwill be hereinafter which the light vbeam was broken up in a manner `such that the formation of a perfect image of thelight filament, in the focal plane o-f the-reflector, was prevented. This object is accom )lishedb lknurlinfr the Ireflectinff I. C D

plates or, more specifically-by:bending or breaking the segments at right angles to their length so asto form a series of substantially flat reflecting surfaces. I'have vfound-that forthe most satisfactory accomplishment of this object, it is preferable to malte these reflecting surfaces of a width which is less than the width of the filament in the lamp. This serves to completely break down any images of the filament, and produces a light beam which is of uniform intensity, and does not contain the usual light and dark rings, or dark spots, obtain-ed in the use of the ordinary type of reflector when the lamp is positioned out of focus. The breaks in the plates o-r reflecting segments are indicated in Figs. 2 and 3 by reference numeral 36. The illustration in Fig. 3 is slightly exaggerated to clearly illustrate this knurl or broken effect. In actual practice, the surfaces 36 are more nearly flat than they are as shown in the drawing.

The fan 18, as shown in Fig. l, may be of any well known construction, and While I consider it preferable, especially for motion picture work, to employ an exhaust fan which will draw the heated air through the spaces between the plate segments 22 and 221 from the region in front of the reflector, it will be understood that a blower type of fan, in which the cool air from the region behind the reflector is blown therethrough into the drum l2, may be advantageously employed in connection with some types of lighting units such as, for example, the lights which arev used for illuminating airplane landing fields. This circulation of air as mentioned above is designed primarily to cool the reflecting blades.

The type of fan shown in Fig. l consists of a shaft or arm 36, the inner end of which is mounted in a hollow projection 2l formed l on the hub 2l at the rear of the reflector. The fan 18 is mounted on a suitable hub 3'? which is carried by a bearing 38 mounted on the bar 36. The hub 37 is provided with a pulley wheel 39 by means of which the fan may be driven from any suitable source of,

power not shown. A fan housing 40 is sho-wn as being mounted in the rear flange 16 formed on the lamp drum l2, such housing` being provided with front and rear openings with to form a co-ncave -support radially mounted -operating to form vtractionrelative to said attaching means.

4:1 and 41', respectively, to admit the passage .a fan for vnot only cooling 'the region illuvminated by the lamp, but also for cooling the reflector itself. u It will be apparent that while I have described the reflector asbeing made up of two concentric sets of reflecting plate segments,that this type ofconstruction may be employed in making reflectors of `any'desired size simply byusinga greater number of segments, or in the event va small vreflector is desired, the unitmay consist of a. single set of segments of any. desired radius. It will also beapparent that While -Ihave described the reflectorasl` being mounted upon a cage-like frame support, that any well Vknown type of support may be employed as, :for example., a solid dome'provided With ribs to support the reflecting plates, and if the lamp isto be ventilated, this dome may be provided With a series ofapertures for admittingfree circula-tion of air. f

It is to be understood'thatfwhile I have herein described and illustrated one preferred `form 'of myfinvention, that'theinvention is not limited tothe `forth precise construction set fabove, but includes Within its scope whatever'changes that fairly come Within the spirit of the appended claims.

Iv claim as my invention:

l. A reflector of the class described embodying: a hub; a plurality of curved radial Varms extending outwardly'from said hub; a plurality of concentric ring members secured to said radial arms and cooperating therea plurality of metal reflecting segments radiallymounted on said suppertwithftheirbacks engaging said concentric rings Aso asto form a substantially uninterrupted concave reflecting surface; and means for rigidly securing one end only of each segment to 4said support, "the other ends of the segments being free to move along the supportwith expansion and contraction ofthe segments.

2. A. reflector of theclass described embodying: a support consistingof a hub, a

plurality of radial arms extending outwardly fromsaid hub, anda plurality of concentric ring members secured to said `radial arms; anda reflecting membery consisting of a plurality of concentric rings ofmetal segments on said support and coa substantially uniform reflecting surface; meansfor attachingithe outer end portions only of said segments'to said ring members; and means for guiding said segments during their expansion or: con- 3. reflector ofthe class described embodylng a concave support of predetermined focal length; a plurality of concentric supconcave support during their expansion or contraction.

4. A refiector ofthe class describedrembodying: a concave support of predetermined focal length; a plurality of concentric supporting rings in said support forming'a plurality of concentric reflector supporting zones therein; refiector means in each zone comprising a plurality of segments radially mounted in each zone; means for securing` the segments therein being so'arranged that the outer end of each segment of an inner zone extendsover the inner ends of two segments in the next adjacent outer zone.

8. Afrelector of the class described embodying: a concave support of predetermined focal length; a plurality of concentric reflector supporting zonesformed in said support; and reflector means in each Zone comprising a plurality of reflecting segments radially mounted in said zones, each segment being secured at one end only to the periphery of itslsupporting zone. n

In testimony whereof, I have hereunto setz my hand at Los Angeles, California, this 8rd day of February, 1930.

- GUSTAV DIETZ.

each segment to the outer supporting `ring of the corresponding zone, said zones andrthe segments therein being so arranged that Y the outer ends of thesegments of an inner zone extend over the inner ends -of the segments in the next adjacent outer zone; and means for guiding the segments-to the curvature of the concave supportl during their expansion or contraction. Y

5. A reflector of the class described embodying: a concave support of predetermined focal length;a plurality ofconcentric supporting rings in said support forming a plurality of concentric reflector supporting zones therein; reflector means in each zone comprising a plurality of segments radiallyl mounted in each zone; means for securing each segment to the'outer supporting ring of the corresponding zone; and means in between the adjacent segments inv one of said zones for maintaining a uniform separation between said segments and Afor guiding `said segments to the curvature of said support.

6., A reflector' of the class ydescribed embodying a concave support of predetermined yfocal length, a plurality of concentric supporting rings in said support forming a plurality of concentric reflector supporting zones therein; reflector means in each zone comprising a plurality of long narrow slightly tapered segments radially mounted in each zone and means forfiXedly securing each segment at its outer end only to the outer supporting ring of the corresponding zone.

7 A reflector of the class described em-V bodying: a concave support of predetermined focal length; a plurality of concentric supporting rings in said support forming a plurality of concentric reflector supporting zones therein; reflector means in each zone comprising -a plurality of segments .radially mounted in each zone; means for securing each segment to the outer supporting ring of the corresponding zone, said zones and

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