US3659092A

US3659092A - Movie light

Info

Publication number: US3659092A
Application number: US698045A
Authority: US
Inventors: David R Dayton; David N Brooks
Original assignee: Sylvania Electric Products Inc
Current assignee: GTE Sylvania Inc
Priority date: 1967-12-19
Filing date: 1967-12-19
Publication date: 1972-04-25
Anticipated expiration: 1989-04-25

Abstract

A compact light source having a short, straight elongated tubular iodine incandescent lamp. The ends of the lamps are close to the reflector to prevent condensation of the iodine. The reflector is in the shape of a surface of revolution formed by two half-parabolas tilted slightly toward each other, but having the same focus. The light source can be tilted if desired, and can be used as a ''''movie light'''' for making motion pictures.

Description

United States Patent Dayton et al.

[54] MOVIE LIGHT [72] Inventors: David R. Dayton, Beverly; David N.

Brooks, West Peabody, both of Mass.

[73] Assignee: Sylvania Electric Products Inc.

[22] Filed: Dec. 19, 1967 [21] App1.No.: 698,045

Related U.S. Application Data [63] Continuation of Ser. No. 26,228, May 2, 1960, abandoned.

[52] U.S. Cl. ..240/1.3, 240/1 1.4 R, 240/20, 240/103 R [5 l] Int. Cl. ..F2ll l/00, G03b 15/02 [58] FieldofSearch ..240/1.3,11.4,2C,7.1C,

240/8.l8,l0.5,10.6,11.2, 20, 41.35, 41.35 E, 41.55, 52 HT, 81 P, 103 B; 313/222 [56] References Cited UNITED STATES PATENTS 2,003,342 6/1935 Cavanaugh ..240/1 1.4

2,211,258 8/1940 Delfel .....240/41.35 E 2,259,107 10/1941 Halvorson ..240/1 1.4 2,678,996 5/1954 Johnson ..240/41.35 X 2,883,571 4/1959 Fridrich et a1... ..313/222 2,907,870 10/1959 Calmes 240/41.35 X 2,953,675 9/1960 Kluge ..240/1 3 3,021,422 2/1962 Ogier et al. .......240/1 .3

Primary Examiner-loseph F. Peters, Jr. An0rneyNorman J. OMalley and Laurence Burns [5 7] ABSTRACT 3 Claims, 6 Drawing Figures PATENTEnmzsamz 3,659,092

SHEET 10? 2 DA R. DAYTON 33 gl DA N. BROOKS uvmvrons 24 $1.; 31

BY 2 ATTORNEY PATENTED APR 2 5 i972 SHEET 2 BF 2 DAVID R. DAYTON DAVID N. BROOKS INVENTORS AT TOR N EY MOVIE LIGHT This application is a continuation of our co-pending application Ser. No. 26,228, filed May 2, 1960 and now abandoned.

This invention relates to incandescent lamps generally, and more particularly to incandescent lamps having a high luminous efficiency, and to equipment for their use, particularly in the making of motion pictures, equipment providing light for that purpose being herein referred to as a movie light".

Normally, movie light equipment consists of a bank of two or more incandescent lamps positioned on a common beam held separately from a movie camera to provide the required amount of illumination for motion picture making. Equipment of this type is expensive to make and very awkward to manipulate when used in conjunction with a motion picture camera.

Such equipment also has many disadvantages as far as safety is concerned, especially from accidental contact with the exposed hot lamps and the contact of the lamps with inflammable material.

An object of this invention is to provide a movie light that will overcome the disadvantages of the above-mentioned equipment whereby the lamp itself is a compact unit including a lamp having a large wattage in a small space, such as an iodine lamps, as its source of illumination, the lamp being fitted into a housing of a fixture suitable to be attached to a motion picture camera, whereby a compact unitary structure is attained.

Another object of our movie light is to provide a means -whereby the amount of illumination, if need be, can be decreased by tilting the light source away from the subject matter. The tiltable construction has another decided advantage in that when the movie'light is placed to rest after operation, the lamp housing can be tilted to a horizontal position to place the lamp and reflector out of contact with the surface of the resting place.

And still another object of our invention is to provide a lamp housing consisting of a small, high power lamp and a reflector with spaced-apart cooling fins in relationship with the reflector to dissipate the heat that is generated by the lamp.

This is an important feature of the invention because the lamp used in the device ,has a very small envelope for the wattage used, so the heat dissipation is extremely large. We have discovered that combination of cooling fins with the reflector is effective in dissipating large amounts of heat.

Other objects, features and advantages will be apparent from the following specification in connection with the accompanying drawings in which:

FIG. 1 is a front elevational view of the movie light structure showing the iodine lamp positioned in a reflector of the lamp housing and the relationship of the movie light with a conventional camera, the camera shown in phantom lines;

FIG. 2 is an elevational cross-sectional view, taken on the line 2-2 of FIG. 1, of the movie light showing in particular the cooling fins and their relationship to the reflector and the electrical components located within the lamp handle;

FIG. 3 is a plan view of the lamp housing, taken on the line 33 of FIG. 2, showing in particular the position of the cooling fins in relation to the reflector;

FIG. 4 is a schematic of the movements of the tiltable lamp housing showing in particular the pin and slot arrangement necessary in the moving of the housing from its normal vertical position (shown in solid lines) to its extreme horizontal position shown in phantom lines);

FIG. 5 is a schematic view showing the method used in the forming of the two half-parabolas in making of the reflector; and

FIG. 6 is a view of the reflector and a lamp held within the reflector and showing in particular the dimpled area.

Referring to FIG. 1, the movie light has a grip-size handle 1 of T-shaped construction. Projecting upwardly from the top T- part of the handle 1 is a pair of support bars 3 and 5, the upper portions of the bars 3 and 5 terminating in conical shaped pivot bearings 7 and 9 respectively to form a rigid stand.

Positioned between the conical bearings 7 and 9 and spaced above the handle 1 is a movable lamp housing 11. The housing 11 is constructed of an electrically insulating material and is U-shaped in form. It is supported on the bars 3 and 5 by the pivot bearings 7 and 9 respectively. A reflector 13 having a flat front edge is fixed to the opening formed of the U-shaped housing 11 by suitable screws 15 that hold the reflector l3 rigidly to the lamp housing. The reflector 13 is provided with oppositely disposed apertures 17 horizontally spaced apart lying in the plane of the focal point of the reflector. A pair of lamp holding clips 19, one projecting through each aperture, have a two-fold purpose in that they provide a rigid mechanical securing means for lamp 21 and that they are electrically connected to a source of power. A lamp 21, small in diameter but elongated in length that has a large wattage is used; in this instance, an iodine lamp.

Such a lamp has an incandescent filament operating in an atmosphere of iodine vapor to protect it from excessive evaporation and to maintain its light output at a high value, enclosed in a small diameter tubular envelope of quartz or other highly refractory light-transmissive material. For use in a home movie light, the quartz envelope should be quite short, and the filament of the coiled-coil type, to provide a compact lamp of extremely high power input for its surface area. The tubular portion of the lamp can be about 1% inches long and three-fourths inch in diameter, and the flat end portions, through which the lead-in ribbons emerge, can be about fiveeighths inch long and about one-half inch wide, with a thickness of about onesixteenth inch. The coiled-coil filament of tungsten wire is designed to carry about 600 watts, the voltage being about 1 10 volts and the current about 5.5 amperes.

Other halogens can be used instead of iodine to provide the atmosphere around the filament in the lamp.

The lower reduced section of the handle 1 has a laterally projecting metal support bracket 23 which is rigidly fixed to an enlarged collar 24 at the base of the handle. At the distal end of the bracket 23 a hand set screw 25 is provided, the purpose of the bracket and screw arrangement is to securely hold a conventional movie camera 26 (shown in phantom lines) in unison with the movie light. The screw 25 can be adjustable laterally for various size cameras.

The internal construction of the movie light can be seen in FIG. 2 wherein the handle 1, made of any suitable insulating material, has an upper hollow portion 27 and a lower hollow portion 29. The upper hollow portion 27 provides adequate space for an operational on-off switch 30. The switch 30 is fixed to the upper part of the hollow portion 27, the operational button 31 of the switch 30 extends through an opening 46 in a rear cover plate 32 which is removable for service of switch. The button 31 is conveniently positioned on the handle l for ease of operation.

The lower hollow portion 29 provides space for a conventional fuse 33, the purpose of this fuse 33 being to prevent excessive current to flow to the lamp 21 on burnout thereby preventing damage to the lamp. The fuse 33 is positioned in the hollow portion 29 through an opening 35 located in enlarged collar 24 and held in place by a screw cap 37. The power source for the movie light can be a conventional outlet over insulated wire 38. The electrical connection, not fully shown, consists of a wiring from a power source over insulated wire 37 .to the switch 30, from the switch to the lamp clips 19.

The support bars 3 and 5 are tubular in construction as seen in FIG. 4 to provide excess for the electrical wire 38 to be connected between the power source and the switch 30 to the clips 19 located in the reflector 13.

The lamp housing 11 pivotally mounted above the handle 1 has a hollow portion 39 as formed by its U-shape as seen in FIGS. 2 and 3, this hollow portion 39 being considerably larger than the depth of the reflector 13. Fixed to the rear surface of the reflector 13 are a series of flash metal fins 41, equally spaced apart and extending vertically the height of the reflector 13. The fins 41 and their relative spacing provide a cooling arrangement whereby the extreme heat generated by the lamp 21 will be dissipated through the back of the reflector 13, the normal current of air will carry the heat away from the reflector, thus providing cooler operation for the lamp. The reflector and fins can be cast of aluminum, if desired, with the actual reflecting surface plated with rhodium to increase its reflectivity. This plating increases the reflectivity, which is desireable, because the aluminum used for castings generally contains too much impurity, such as silicone to be highly reflective of itself.

The lamp housing 11, as seen in FIG. 4, has another unique feature in that it can be positioned from its normal vertical operational position, as shown in solid lines in FIG. 4, to a limiting horizontal position shown in phantom lines in FIG. 4. The horizontal position shown in FIG. 4 has a decided ,advantage in that the housing holding the lamp can be positioned in this way when the movie light is at rest or after operation. Resting in this way after actual operation, the lamp, being still hot from use, will be distant to the surface of the resting place, therefore preventing injury to the surface by the heat of the lamp.

The movement of the lamp housing is limited from the vertical position to the horizontal position and any point within this limiting arc by pins 43 that are secured to either side of the lamp housing 11. The pins 43 are in register with slots 45 cut in the pivot bearings 7 and 9 respectively.

In order to reflect a broad beam, a deviation in the parabolic curve is used in the reflector. The cross section of the reflector is that of two half-parabolas whose axis are tilted at about 7V2 to the axis of the reflector as a whole, as shown in FIG. 5, the axis A and B meeting at the focus F of their respective parabolas. This spreads out the beam and broadens it, but may produce a dark center of the beam at distances beyond the point where the axis of the two half-parabolas meet. To avoid that, small depressions or dimples about a thousandth of an inch deep and say one-sixteenth inch in diameter, can be hammered into the surface with a hammer and peening too] over the reflecting surface, for example about one-quarter inch apart, to cause enough deviations in the beam to fill in the center of it with light. These dimples can be confined to the center of the reflector, if desired, as in FIG. 6.

Another method that can be used to overcome the dark center is to score spaced-apart vertical creases in the reflector.

This will also cause added deviations in the beam to eliminate the dark area.

The space between the two half parabolas Aand B can be joined by the arc of a circle S, and the composite curve A-S-B then rotated about the axis C of the entire curve to give the surface which the reflector should have. An angle of tilt of 79? to 10 was found very effective.

By having the reflector close to the lamp 21, the ends of the latter are heated by reflected radiation, thereby keeping them from burning out enough'to condense the iodine out at the ends of the tube. Bringing the filament close to the end of the lamp also aids in keeping the ends of the lamp hot.

While we have illustrated and described certain embodiments of our invention, it will be obvious to those skilled in the art that various changes and modifications may be made without departing from the true spirit and scope of the invention as defined in the appended claims.

What we claim is:

1. A compact light source comprising a reflector in the shape of a surface of revolution having an open end, means in said reflector for holding a short, straight elongated tubular lamp whose length is substantially the same as the maximum diameter of the reflector, and a short straight elongated tubular iodine incandescent lamp so held by such means along a diameter of said reflector, said tubular lamp having a coiledcoil filament along its longitudinal axis, said lamp having a power input of at least about 400 watts per inch of the tubular portion of the lamp, the reflector being close enough to the ends of the lamp to heat them sufficiently to prevent condensation of the iodine at said ends.

2. The light source of claim 1 m which the reflector IS in the shape of a surface of revolution formed by two half-parabolas tilted slightly toward each other but having the same focus.

3. A compact light source comprising a reflector in the shape of a surface of revolution having an open end extended to form a flat approximately rectangular flange around said openv end, and a small compact iodine incandescent lamp in said reflector in light-reflecting relationship therewith, a housing behind said reflector and attached to and behind said flange, the top and bottom of said housing being open to permit circulation of air around the back only of the reflector to cool the same, the front of said reflector being in position to reflect heat onto the lamp envelope to heat the ends thereof.

Claims

1. A compact light source comprising a reflector in the shape of a surface of revolution having an open end, means in said reflector for holding a short, straight elongated tubular lamp whose length is substantially the same as the maximum diameter of the reflector, and a short straight elongated tubular iodine incandescent lamp so held by such means along a diameter of said reflector, said tubular lamp having a coiled-coil filament along its longitudinal axis, said lamp having a power input of at least about 400 watts per inch of the tubular portion of the lamp, the reflector being close enough to the ends of the lamp to heat them sufficiently to prevent condensation of the iodine at said ends.

2. The light source of claim 1 in which the reflector is in the shape of a surface of revolution formed by two half-parabolas tilted slightly toward each other but having the same focus.

3. A compact light source comprising a reflector in the shape of a surface of revolution having an open end extended to form a flat approximately rectangular flange around said open end, and a small compact iodine incandescent lamp in said reflector in light-reflecting relationship therewith, a housing behind said reflector and attached to and behind said flange, the top and bottom of said housing being open to permit circulation of air around the back only of the reflector to cool the same, the front of said reflector being in position to reflect heat onto the lamp envelope to heat the ends thereof.