US3152766A

US3152766A - Lighting device

Info

Publication number: US3152766A
Application number: US170207A
Authority: US
Inventors: Wetzel Joseph
Original assignee: ANCIENS TUZET Ets
Current assignee: ANCIENS TUZET Ets
Priority date: 1961-02-03
Filing date: 1962-01-31
Publication date: 1964-10-13
Anticipated expiration: 1981-10-13
Also published as: GB965940A; BE612976A; LU41144A1; FR1287572A

Description

Oct. 13, 1964 J. WETZEL LIGHTING DEVICE Filed Jan. 31', 1962 am n '7 panying drawing wherein: FIGURE 1 is a front v1ew with parts broken away, illustrating a lighting device according to this invention;

United States Patent LIGHTING DEVICE Joseph Wetzel, 108 Ave. Denfert Rochereau, Paris, France, assignor of one-half to Anciens Etablissements Tuzet, Paris, France, a socit anonyme Filed Jan. 31, 1962, Ser. No. 170,207 Claims priority, application France, Feb. 3, 1961,

851,582, Patent 1,287,572 2 Claims. (Cl. 240-4629) This invention relates in general to lighting devices and has specific referenceto devices of this character wherein the intensity of the emitted light can be gradually increased and decreased through simple yet efficient means.

As a rule, the light emitted from electric lamps is gradually increased and decreased by adjusting the intensity of the current passing through the lamp filament or filaments by means of rheostats or variable chokes, with these conventional means the illumination of the different surfaces receiving the light vary in proportion tothe intensity of the light source and their uniformity remains constant. t

In the device constituting the subject-matter of this invention the intensity of the light source remains fixed and the light gradation is obtained by means of shutters displaceable across the light beam. Thus, the costly and cumbersome apparatus necessary for regulating the electric current applied to the lamps can be dispensed with. I

It is already known to utilize screens for absorbing or blocking one fraction of the light emitted by a light source, but under such conditions that when said screens are moved across the light beam the area of the illuminated surface or the uniformity of the illumination are modified, for example in the specific case of theatre stage lighting.

Light gradation as obtained with the device of'this invention will practically not impair or change the extent of the illuminated surface while maintaining at all the vpoints ofthis surface the desired uniformity of the illumination.

It is another advantageous feature of this invention to maintain themcomposition of the lamp radiation and therefore the light color.

This result is obtained by combining into a same device a linear light source, a lighting apparatus designed to give parallel and also linear images of the light source,

and a system of movable shutters adapted, from the very opening of the screen system, to permit the passage of the light rays issuing from all the points of the light source and the images formed by the lighting apparatus,

' so that these rays cross one another in a slit formed by ice direction. A cylindrical reflector 5 disposed behind the lamp 2 and coaxial with the filament 3 reflects toward the axis the light rays emitted backwards. With this optical system a rectangular light beam characterized by a considerable width and capable of covering a rectangular surface is obtained.

According to this invention, two semi-cylindrical

movable shutters

6a, 6b coaxial with the filament 3 of the lamp are disposed between the lamp 2 and the blades 4. Their length is calculated with a view to block the light beam completely when they contact each other centrally of the projector (as shown in chain lines in FIG. 1). These screens are connected to nuts 7 engaging leading screws 8a,-8b having opposite threads whereby when these screws are rotated the

shutters

6a, 6b are gradually moved away from or towards each other. Thus, a slit 15 is formed in the centre which widens gradually and permits the passage, immediately as the opening movement begins, of a constant-height light beam of relatively great width. On the other hand the intensity of the beam which is zero initially increase-s gradually as the slit widens, to reach a maximum intensity when the screens are retracted completely on the sides (as shown in dashed lines).

The two leading screws may consist of a single threaded rod 8 having two oppositely threaded portions 8a, 8b.

The screw 8 is rotatably driven from a small electromotor 9 through a gear reduction unit 10 comprising for example two pinions of modulus 1 and two pinions of modulus 10, all made of Celoron (Registered Trademark) or like material (resin-impregnated fabric).

The motor 9 is disposed coaxially with the lamp filament (see FIG. 3) and drives a fan 14 for cooling the projector (FIG. 1).

The leading screw 8 is housed in a rear casing 11 of the apparatus and the bottom 12 of this casing is detachable to permit the inspection and maintenance thereof.

Limit-switches, ON and OFF switches, and signalling switches (not shown) may be provided according to the known practice; preferably these switches are responsive to theleadingscrew and nuts, and mounted in the rear casing 11 where they can be inspected or repaired when necessary. V

The front central portion of the projector is closed by a detachable glass window 13 permitting the passage of FIGURE 2 is a cross-section taken upon the line 11-11 1 p of FIG. 1; and

FIGURE 3 is another cross section taken upon the line III-III of FIG. 1.

the light beam and the replacement of the filament lamp 2.

The projector sides are closed by plates 1 detachable notably on the side of theelectromotor 9 to permit regular inspection and maintenance of the mechanical components of the apparatus.

The gradual increase and decrease of the light intensity is obtained by remote control means associated with the electromotor whereby the latter can be rotated in either effect. Color screens may be mounted in front of the: I V

projector, if desired. e

The light graduation may be regulated with this device from a control board comprising push-button switches for controlling the lamps 2 of the projectorsand the motors 9 operating the

shutters

6a and 6b. This control board may have relatively small dimensions and can easily be mounted at any desired location for controlling the lighting. I V

The above-described device meets the requirements for producing a simultaneous and gradual increase or de- 3 crease of the illumination at all the points of a givensurface, since from the very beginning of the opening movement of

shutters

6a, 6b the slit 15 receives crossed light rays directed downwardly and from right to left, and issu-, ing from the whole length of the filament 3 either directly or after being reflected by the blades 4 and reflectors 5. Thus, the surface'to be illuminatedis. covered completely by the light rays. As the slit 15 widens out a greater number of rays are distributed over the surface, thus ensuring a gradual increase of its illumination.

Other optical devices may be imagined without departing from the basic principles of this invention. Thus,

for example, the blades 4 may be mounted behind the lamp 2 and so disposed that they are tangent to an envelope surface of substantially cylindrical configuration of which the axis is coincident with the lamp filament 3. It is also possible to substitute this reflecting cylindrical surface for the blades, the cross-section of this surface being of parabolic configuration in this case if it is desired strongly to concentrate the light. In all cases the essential requirement to be met is that the light source be linear and of relatively great length, and that the optical device reflects or refracts the light rays in such a manner that the rays are issued from images parallel to the filament. The movable screens should be so designed that as they move away from each other the light beam is gradually allowed to pass therebetween, symmetrically in relation to the mesial plane of this beam.

The above-mentioned shutters may be replaced by shutters so disposed as to block the light beam when it leaves the projector. They are moved towards and away from each other under the control of means similar to those described hereinabove.

The same dispositions are applicable to systems incorporating electric discharge tubes, notably fluorescent tubes, and in general to any light source of relatively great length, the screens being so disposed as to gradually uncover the light rays emitted by the different points of v the linear light source.

conjunction with preferred embodiments, it is to be understood that modifications and variations may be resorted to without departing from the spirit and scope of the invention, as those skilled in the art will readily understand. Such modifications and variations are considered to be withinthe purview and scope of the invention and appended claims. I

cal edges, said shutters being slidably mounted on a single horizontal axis in said housing for movement toward and away from each other so as 'to define an adjustable slit opening between the adjacent vertical edges for permitting the passage of said beam of light in conform the gradation is obtained bymore or less uncovering a variable surface of the diffusing glass. Under these conditions, a single shutter uncovering the diffusing surface from one of its ends may be substituted for the two shutter halves 641 and 6b.

Although the present invention has been described in ance with the size of said slit opening.

2. An incandescent lighting device comprising a support housing, an elongated light bulb having a horizontal axis and mounted in said housing for projecting a beam of light, reflector means positioned in said housing behind said light bulb in spaced parallel relation to said horizontal axis of the bulb, a pair of substantially identical semi-cylindrical lightblocking shutters in front of and coaxial with said elongated light bulb and in spaced parallel relation to said horizontal axis of the bulb and having adjacent vertical edges, said shutters being slidably mounted on a single horizontal axis in said housing for movement toward andnaway from each other 'so as to define .anadjustable slit opening between the adjacent vertical edges, and adjustment means operatively connected to said shutters for increasing and decreasing the aperture size of said slit opening such that a beam of light is permitted to pass in conformance with said aperture size.

References Cited in the file of this patent V UNITED STATES PATENTS

Claims

1. IN AN INCANDESCENT LIGHTING DEVICE INCLUDING A SUPPORT HOUSING, AN ELONGATED LIGHT BULB HAVING A HORIZONTAL AXIS AND MOUNTED IN SAID HOUSING FOR PROJECTING A BEAM OF LIGHT, REFLECTOR MEANS POSITIONED IN SAID HOUSING BEHIND SAID LIGHT BULB IN SPACED PARALLEL RELATION TO SAID HORIZONTAL AXIS OF THE BULB, AND LIGHT BLOCKING MEANS IN FRONT OF SAID BULB INCLUDING A PAIR OF SUBSTANTIALLY INDENTICAL SEMI-CYLINDRICAL SHUTTERS IN SPACED PARALLEL RELATION TO SAID HORIZONTAL AXIS OF THE BULB AND HAVING ADJACENT VERTICAL EDGES, SAID SHUTTERS BEING SLIDABLY MOUNTED ON A SINGLE HORIZONTAL AXIS IN SAID HOUSING FOR MOVEMENT TOWARD AND AWAY FROM EACH OTHER SO AS TO DEFINE AN ADJUSTABLE SLIT OPENING BETWEEN THE ADJACENT VERTICAL EDGES FOR PERMITTING THE PASSAGE OF SAID BEAM OF LIGHT IN CONFORMANCE WITH THE SIZE OF SAID SLIT OPENING.