IL28689A - Variable beam spotlamp - Google Patents

Description

PATENTS FORM NO. 3.

PATENTS AND DESIGNS ORDINANCE SPECIFICATION 'VARI We, MOLE-RICHARDSON CO. , a company incorporated under the laws of the State of California, United States of America of 937 North Sycamore Avenue, Hollywood, California, United States of America DO HEREBY DECLARE the nature of this invention and in what manner the same is to be performed, to be particularly ascertained in and by the following statement :- The present invention relates to spot-lamps of the type having an adjustable or variable beam, and it relates more particularly to a spotlamp of this general type wherein the light bulb is fixedly mounted within the lamp housing and adjustability of the beam is accomplished by axial movement of a reflector in the housing.

It is well known in the lamp art to provide for adjustability in spotlamps to permit variation of the beam from a relatively narrow, "spot" type beam to a relatively wide, "flood" beam. Conventionally, the adjustment has been accomplished by moving the light bulb back .and forth in the housing relative to a fixed focusing reflector or a fixed lens such as a Fresnel lens. In the past this type of adjustability has been generally satisfactory because spot-lamps were of sufficient size to contain the necessary adjusting mechanism and for adequate heat dissipation. Also, the usual light bulb had a single socket mounting, which permitted relatively simple adjusting equipment.

However, recent advances in the lighting art have resulted in high-intensity light bulbs which are very small in size, and in particular the double-ended quartz lamp type of bulb which is a small cylindrical or tubular bulb having electrical contacting means at both ends therof . An example of a typical double-ended quartz lamp of this type is a 1,000 watt quartz lamp having a bulb part that is only about 5/8 of an inch in diameter and about high intensity light bulbs have permitted a substantial reduction in the overall size of spotlamps which employ them, this has at the same time resulted in a number of problems associated with the provision of a movable bulb for focusing.

For example, where a double-ended, high intensity quartz, lamp is movably mounted for focusing in a compact spotlamp, an undesirably large amount of space is required by the fact that two movable sockets must be positioned in opposite sides of the lamp housing, and relatively complicated actuating mechanism must be provided for simultaneously moving both of the sockets back and forth in the housing. Such movable sockets nevertheless must be minimized in size because of the considerable amount of space which they displace in their back and forth travel to provide beam adjustment, and this generally results in an inadequate socket structure for withstanding or dissipating the intense heat that is present in such a compact spotlamp.

Another problem with modern high intensity, compact spotlamps which are made adjustable by movement of the lamp bulb is that various accessories which are mounted on the front of the lamp housing, such as barn doors, spun glass diffusers, color correcting plates, and others, are more or less vulnerable to excessive heat, and when the light bulb is moved to its forwardmost or "flood" position, these accessories are likely to become excessively hot from heat that is directly radiated from the bulb movable bulb type spotlamps is that each time the bulb is moved, the wires providing electricity to the sockets are flexed, and electrical connections are stressed. This problem is, of course, magnified with the constricted space and intense heat of a high intensity, compact type of spotlamp.

. A still further problem in connection with such spotlamps having a movable bulb is that any accidental shock against the adjusting knob or lever will be transmitted directly through the movable socket structure to the bulb, and thereby cause a shock to the bulb which is liable to cause expensive damage .

The present invention overcomes these and other problems in the art by providing a variable beam spotlamp wherein the light bulb is fixedly mounted within the lamp housing, and adjustability of the beam is accomplished by axial movement of a relector in the housing with respect to the light bulb .

With the adjustable reflector of the present invention, the light bulb is disposed substantially rearwardly in the housing, at a fixed, maximum distance from the forward rim of the housing to which various accessories are attached. The reflector is then moved betwee the forwardmost minimum spot position and a rearwardmost flood position. This places the light bulb approximately twice as far back from the front of the housing in the present invention than the bulb of a movable bulb type spot- size with reflectors of about 5-1/2 inches diameter, with 1,000 watt double-ended quartz bulbs, in the present invention the bulb will typically be set approximately 4 inches to the rear of the forward rim of the housing, while the bulb in a movable bulb type lamp will, in the flood position, be only about 2 inches from the forward rim of the housing. This means that approximately four times the radiated heat energy will be applied to accessories at the front of the housing in the flood position of a movable bulb type spotlamp as compared with the fixed bulb spotlamp of the present invention.

The objects and advantages of the present invention will appear during the course of the following part of this specification, wherein the details of construction and mode of operation of a preferred embodiment are described with reference to the accompanying drawings, in which: Figure 1 is a front elevational view of a variable beam spotlamp according to the present invention.

Figure 2 is an axial, vertical section taken on the line 2-2 in Figure 1, showing internal details of the lamp, the reflector being adjusted to a generally rearward or flood position in Figure 2.

Figure 3 is an axial, horizontal section taken on the line 3-3 in Figure 2.

Figure 4 is a transverse, vertical section taken on the line 4-4 in Figure 2.

Figure 5 is an enlarged, fragmentary members in the housing.

Figure 6 is an axial, vertical section similar to Figure 2, but with the reflector adjusted to its forwardmost or spot position.

Figure 7 is a horizontal section taken on the line 7-7 in Figure 6, providing a plan view of the reflector assembly and stabilizing spring associated therewith.

Referring to the drawings, a spotlamp 10 according to the present invention includes a housing 12 which is preferably, but not necessarily, generally cylindrical in configuration. Mounted on opposite sides of the housing 12, in diametrically opposed relationship, is a pair of trunnions 14 which are engaged for pivotal mounting by the end portions of a support yoke 16. A clamp knob 18 is threadedly connected to one of the trunnions 14, loosening of the knob 18 permitting pivotal adjustment of the spotlamp 10 about a horizontal axis, and tightening of the knob 18 clamping the spotlamp 10 in its ad-justed position. The housing 12 includes a barrel portion 20 intermediate its ends, which is preferably perforated for ventilation; a forward guide portion 22 in the form of a generally smooth cylinder and a back wall portion 24 providing a generally closed back of the housing. Light baffle members 26 are supported within the perforated barrel 20 to block the passage of light outwardly through the perforations of the barrel, while allowing freedom of ventilation through the perforations of the barrel. portion 20 of the housing, the light bulb preferably being supported in a horizontal position at right angles to the axis of the housing, and symmetrically . arranged with respect to the axis of the housing.

While the present invention is not to be construed as limited to any particular type of light bulb, a presently preferred type of bulb is a small, high intensity double-ended quartz lamp. The light bulb 28 has electrical contacts at its ends which are received in respective spring-loaded sockets 30.

Socket base members 32 carry the sockets 30 and are supported on the insides of the respective trunnions 14, as by means of screws 33.

It will thus be seen that when the light bulb 28 is operatively positioned in a lamp by engagement of its ends in the sockets 30, the light bulb is fixedly positioned with respect to the lamp housing 12. This fixed operative positioning of the light bulb is not in any way disturbed when the spotlamp beam is adjusted, as will be apparent from the discussion of the adjustment means set forth hereinafter. The sockets 30 are arranged so that the light bulb can be simply and conveniently removed from engagement with the sockets 30 and replaced by - a new light bulb when necessary. As is apparent from Figures 1 and 3 of the drawings, the light bulb 28 is fully accessible from the open front end of the ous ing 12, whereby removal and replacement of a light bulb can be accomplished without requiring any disassembly of parts or special adjustments. assembly 34 mounted in the housing 12, and comprising a forwardly flaring reflector 36 and a strap type of mounting 38 attached to the reflector 36 and disposed generally rearwardly of the reflector. Any desired reflector configuration may be chosen according to the specific qualities of the spotlamp beam that are desired. Preferably, the reflector 36 is annular, having a cupped rear end portion 40 disposed to the rear of the light bulb 28, and the reflector flaring forwardly and outwardly from this rear portion to its forward edge, at which it is provided with an out-turned flange 42 and a forwardly turned annular rim 44. The annular rim 44 is slida-bly engaged within the forward guide portion 22 of housing 12 for axial sliding movement of the reflector 36 in the housing.

The reflector 36 is provided with longitudinally arranged, diametrically opposed slots 45 through which the light bulb 28, and as seen in Figure 3, sometimes the sockets 30, extend. Accordingly, the elongated slots 45 in the reflector permit free axial sliding movement of the reflector relative to the light bulb 28 and the sockets 30 without disturbance to the fixed positioning of the light. bulb 28. Also, the slots 45 permit full access to the light bulb 28 from the open front end of the housing for removal and replacement of the light bulb.

The mounting bracket 38 includes a base portion 46 which is preferably vertically arranged, and is disposed generally at right angles to the axis and 50 of the mounting bracket are integral with the base portion 46, and extend forwardly and outwardly to the out-turned flange portion 42 of the reflector, the legs 48 and 50 having outwardly directed ears 52 at their respective forward ends. These ears 52. are secured to the reflector flange 42 by suitable fastening means, as for example, by pop rivets 54.

The upper leg portion 48 of the mounting bracket 38 is provided with a keyway section 56 immediately forward of the base 46 of the mounting bracket, this keyway section 56 extending parallel to the axis of the housing, and hence in alignment with the path of axial movement of the reflector assembly in the housing.

A support bar 58 is fixedly secured in the rear portion of the housing, preferably by attachment to the back wall 24 as by means of screws 60. The support bar 58 is preferably vertically arranged, and extends across the central axis of the housing. A bore 62 aligned with the central axis of the housing extends through the back wall 24 and the support bar 58, to receive an adjusting shaft 64 for rotational movement therein. The adjusting shaft 64 has an adjusting knob 65 secured to its rear end to the rear of the back wall 24 of the housing, and shaft 64 is provided with a helical groove 66. A roll pin 67 is supported in a suitable aperture in the support bar 58, and has an end that is engaged within the helical groove 66 of the adjusting shaft, whereby rotation of the knob 65 and hence of the .... and rotation of the knob and shaft in the opposite direction will cause the shaft to retract rearwardly along the axis of the housing. The forward end portion of the shaft 64 extends through an opening in the base portion 46 of the bracket, being rotatable with respect to the bracket but being keyed against axial movement relative to the bracket, so that the axial traveling movement of the shaft 64 which results from rotation of the knob 65 will be imparted to the bracket 38. The forward tip 68 of the shaft 64 is rotatably engaged within a small opening in the rear end portion 40 of the reflector, to secure the rear end portion of the reflector against lateral movement in the housing. Thus, the bracket 38 and the reflector 36 are effectively secured together at three points, two points being where the ears 52 are secured to the flange 42 of the reflector, and the third point being the point where the forward tip 68 of the shaft engages the rear end of the reflector.

A stabilizing spring 70, in the form of a leaf spring, is fixedly secured at its rear end to the upper end of support bar 58, as by means of screws 72. The spring 70 is bifurcated at its forward, free end, to provide a pair of laterally. spaced positioning tangs 74 which are bent downwardly along the opposite sides of the axial keyway section 56 of the mounting bracket 38. The body of the spring 70 immediately to the rear of the tangs 74 is engaged against the upper surface of the keyway section 56 of the bracket and applies a downward biasing positions along the side edges of the keyway section 56 as best shown in Figures 6 and 7 of the drawings.

Engagement of the spring 70 with the key-way section 56 of the reflector mounting bracket serves a number of important functions. First, the engagement of positioning tangs 74 along the side edges of the keyway section 56 keys the entire reflector assembly 34 against rotation in the housing, and thereby prevents the edges of the reflector slots 45 from being shifted against either the light bulb 28 or the sockets 30, insuring the free axial sliding action of the reflector assembly. Another function of the spring 70 is that the frictional engagement of the spring against the upper surface of the keyway section 56 prevents the inadvertent sliding of the reflector assembly from the weight of the reflector assemby when the spotlamp is tilted up or down from a horizontal position on the trunnions 14. A further function of the spring 70 is to bias the reflector rim 44 downwardly against the forward guide portion 22 of the housing to prevent rattling in the spotlamp when the spotlamp is moved. This latter function of the spring is important to prevent undesired noise when the lamp is being dollied from one position to another during the photographing of a motion picture.

As shown in Figure 3, the electrical input cable or cord 76 preferably enters the housing 12 through an opening in the back wall 24, being secured in position by a suitable cable grip 78, and the none of the wiring or electrical connections will be in any way flexed or stressed during operation of the spotlamp.

Adjustment of the spotlamp beam is accomplished simply by. rotating the adjusting knob 65 at the rear of the housing so as to move the reflector assembly back and forth within the housing. When the reflector is adjusted to a generally rearward position in the housing, as illustrated in Figures 2 and 3, the light beam cast from the spotlamp will be a "flood" type of beam, while movement of the reflector to its forwardmost position as illustrated in Figure 6 will provide a minimum "spot" type of beam.

While the instant invention has been shown and described herein in what is conceived to be the most practical and preferred embodiment, it is recognised that departures may be made therefrom within the scope of the invention, which is therefore not to be limited to the details disclosed herein, but is to be accorded the full scope of the claims so as to embrace any and all equivalent devices.

Claims (1)

1. a front s rear a station ry light source in said housing v prising a p of opposed electrical sockets in housing i sides of the re lector electric light bulb mounted opening tor mounted in the said reflector having a pair of opposed slots in the wall thereof through which said light source said bulb disposed generally within said so that the flector directs light the bulb in a fowardly ting and adjusting connected to said reflector for the reflector generally axially of the so as to vary the width of the said slots permitting such of the reflector without mechanical interference between the re and said light A according to claim 1 wherein said re has mounting bracket attached A spotlamp according to claim wherein said adjusting is engaged between said bracket and the A according to 2 or said mounting b a base portion jacent to the of the and said adjusting comprises threaded adjusting means engaged between claim or mounted the housing longitudinally section of the to the against movement claim wherein a said so to reflector against the housing to iiait rattling of the reflector in the to 4 and herein said threaded adjusting is generally aligned axis of the said longitudinally section of bracket is radially ix said axis and said against rotation of said and reflector said a is according to claim or said spring m comprises a leaf is ed at its free end to a pair o spaced tangs disposed on opposite sides of said longitudinally section of according to any of the preceding said has generally cylindrical guide said has generally forward engaged in said portion for eliding HOROWITZ FOR APPLICANTS insufficientOCRQuality