US3511985A

US3511985A - Adjustable beam lamp

Info

Publication number: US3511985A
Application number: US644590A
Authority: US
Inventors: Joseph A Muscovitch
Original assignee: JOSEPH A MUSCOVITCH
Current assignee: JOSEPH A MUSCOVITCH
Priority date: 1967-06-08
Filing date: 1967-06-08
Publication date: 1970-05-12
Anticipated expiration: 1987-05-12

Description

. y 1970 J. A. MUSCOVITCH 3,511,985

ADJUSTABLE BEAM LAMP 3 Sheets-Sheet 1 Filed June 8, 1967 INVENTOR. JOSEPH A. MUSCOVITCH M y 1 1970 J; A. MUSCOVITCH 3,511,985

ADJUSTABLE BEAM LAMP Filed June 8, 1967 INVENTOR. JOSEPH AMUSCOVITCH ATTORNEY ,May 12, 1970 J. A. MUSCOVITCH ADJUSTABLE BEAM LAMP 3 Sheets-Sheet 5 Filed June 8, 1967 FIG.5

FIG-3.6

INVENTOR. JOSEPH A. MUSCOVITCH BY ATTORNEY PIC United States Patent O 3,511,985 ADJUSTABLE BEAM LAMP Joseph A. Muscovitch, 37 Franklin Ave.,

- Saddle Brook, NJ. 07662 Filed June 8, 1967, Ser. No. 644,590 Int. Cl. F21v 7/06 US. Cl. 24044.1 8 Claims ABSTRACT OF THE DISCLOSURE An adjustable beam lamp having a reflector capable of reflecting a concentrated beam when the light source is located at the focal center thereof and having a light bulb socket and reflector housing mounted for movement relative to each other for positioning the bulb filament at the focal point of the reflector. The reflector is movably mounted within the housing for manual adjustment of the reflector in a position in which its center is located behind the light bulb for producing an intense concentrated beam of reflected light, and selective positions in which curved surfaces of the reflector of lesser diameter are located behind the bulb for producing dispersed beams of variable and controllable spread.

BACKGROUND OF THE INVENTION In many applications, it is desirable to provide a concentrated beam of intense light for illuminating a small area. In machine shop work, for example, where direct light on layout is critical, a bench lamp capable of producing an intense spot is often a necessity. It is usually impractical to provide such spot illumination by bringing an ordinary lamp close to the work, since the lamp interferes with the workers movement, and often gets spattered with oil or the like. It is also desirable to adjust the beam of light to produce illuminated spots of varying areas.

Focussing lamps which will vary the area of light beams are presently available as hospital and dental operating lights, for example. These lamps operate on the principle of varying the spacing between the light bulb and the reflector to provide a limited control over the spot. However, when the spacing between the bulb and reflector is increased, a halo effect is produced, so that the lamps include a Fresnel lens forwardly of the bulb to eliminate this halo effect. The provision of such lens system as well as means for adjusting the bulb position, increases the cost of the lamp to such anextent as to render it impractical for shop use.

Accordingly, an object of this invention is to provide a lamp capable of producing a concentrated spot of light for intense illumination of a small area, and variable by adjustment to produce gradually increasing areas of more diffused illumination.

Another object of the present invention is to provide a lamp of the character described in which a variable area light beam is attained without the use of a lens or lens system. I

Still another object of the invention is to provide a lamp having means for adjusting the bulb and reflector relative to each other in such a manner that the bulb filament may be located at the focal center of the reflector for producing a concentrated beam of parallel rays.

A further object of the present invention is to provide a lamp of the type described which is simple in construction, economical in manufacture, and reliable in operation.

In accordance with the invention herein, there is provided a lamp including a socket for mounting a light bulb and a reflector located behind the light bulb. The reflector is of such type, for example the parabolic type, as to reflect the light emitted by the bulb in parallel rays so as to provide a concentrated beam when the bulb filament is located at the focal center of the reflector. The reflector is mounted within a housing which is movable relative to the light bulb for locating the bulb filament at the focal center of the reflector. The bulb socket is also movably mounted for proper positioning of the bulb relative to the reflector to accommodate bulbs of different sizes. The reflector is also movably mounted within the housing for adjusting the reflected light variably between a concentrated beam and a diffused beam.

Other objects and advantages of the present invention will become apparent from a consideration of the following detailed description when taken in conjunction with the accompanying drawings, in which:

, FIG. 1 is a perspective view of a lamp constructed in accordance with the present invention;

FIG. 2 is a central vertical section of the lamp shown in FIG. 1, with the inoperative position of the socket being shown in broken line;

FIG. 3 is a front elevational view thereof;

FIG. 4 is a perspective view of the heat shield forming part of the lamp assembly; and

FIGS. 5-7 are diagrammatic illustrations of the light patterns produced by the lamp of the present invention for various positions of the reflector relative to the source of light.

Referring now to the drawings and in particular to FIG. 1, there is shown a lamp constructed in accordance with the present invention and designated generally by the reference numeral 10. The lamp includes a conventional threaded socket 12 which is adapted to receive therein a source of light such as a light bulb 14 having a filament 15. Depending from the bottom surface of the socket 12 is a centrally located swivel member 16 which is received between the spaced ears of a bifurcated socket supporting member 18 (FIGS. 2 and 3). A screw 20, extending between the ears of member '18 and through member 16, provides a swivel joint pivotally mounting the socket 12 on the connecting member 18. Thus, the socket is movable between an operative position shown in solid line in FIG. .2, and an inoperative position shown in phantom, the direction of movement being indicated by the arrow 22. It .will be understood that other conventional types of swivel means may be employed instead of screw 20 to permit movement of socket 12.

The socket supporting member 18 has an externallythreaded lower tubular section 24, as shown in FIG. 2. The lower end of the tubular section 24 may be connected with a conventional mechanical swivel arm or support (not shown) so that the lamp 10 may be set inany desired position relative to a base or clamp supporting the mechanical swivel arm. For energization of the bulb 14, the socket 12 may be connected in the conventional manner to a pair of wires (not shown) which extend through the tubular section 24 and the swivel arm section of the lamp to connect the socket 12 and the inserted light bulb 14 with a source of potential through the usual on-oif switch. I

Adjustably mounted on the tubular section 24 of the connecting member 18 is a reflector housing designated generally by the reference numeral, 26. The reflector housing 26 includes a concave hemispherical bodyportion 28 having a bottom opening 30 which extends to one edge thereof and is sized to receive the socket 12 therein,

3 bular section 24 of the socket supporting member 18. A lock nut 36 (FIG. 2) or similar clamping device is mounted on the tubular section 24 and is adapted to abut the sleeve 34 to maintain the reflector housing 26 at a predetermined height relative to the light bulb 14.

As shown in FIGS. 2 and 3, the hollow bracket 32 is sufficiently wide to receive the socket supporting member 18 and a portion of the socket 12 therein, and the communicating opening 30 in housing body portion 28 is also sized to receive the socket therein. Thus, the socket 12 may be pivoted rearwardly to move the light bulb 14 toward the reflector housing and well within the confines thereof. In addition, 'by rotating the reflector housing 26 upon the threaded tubular section of the socket supporting member 18, the housing 26 is moved longitudinally along said threaded section and is thus raised or lowered relative to the socket 12 and its contained light bulb 14. In this manner, the light bulb, regardless of size, may be properly positioned within the reflector housing, as will be presently explained. The lock nut 36 may then be turned into tight frictional engagement with the sleeve 34 to retain the reflector housing in the set position.

Received within the hemispherical body portion 28 of the reflector housing 26, for sliding movement with respect thereto, is a highly polished or mirrored concave reflector 40. More specifically, the reflector housing 26 is provided with a pair of opposed guide members which permit this sliding movement of the reflector 40. Each guide member comprises a screw shank 44 aifixed to the inner surface of the housing 26, and a circular nut 42 threadedly mounted on the screw shank. The nut 42 is formed with one or more legs which act as spacer elements to position the nut a selected distance from the inner surface of the reflector housing body portion 28. Punched out lugs from the reflector housing may be employed instead of the screw shanks 44 and nuts 42.

In assembling the lamp, t-he reflector 40 is inserted within the housing 26 between the screw shanks 44, and the nuts 42 are threaded upon the respective screw shanks until the spacer legs engage the inner surface of housing 26. The nuts 42 prevent movement of the reflector 40 outwardly and away from the housing 26, but permit turning movement of the reflector 40 along the inner surface of the housing.

Secured to the reflector 40, adjacent the upper edge thereof, is an upstanding post 46 which extends through an elongated slot 48 in the top of the concave body portion 28 of the reflector housing 26. The slot 48, as shown in FIG. 1, extends downwardly over a portion of the circumference of the housing body portion 28. The upper end of the post 46 is threaded for mounting an internallythreaded clamping member 50 thereon. The bottom surface of the member 50 is adapted to be screwed into tight frictional engagement with the outer surface of housing body portion 28 to maintain the reflector 40 in a preselected adjusted position relative to the filament in the light bulb 14. In use, the clamping member 50 may be loosened and grasped to move the post 46 within the slot 48, such movement adjusting the position of the reflector 40 with respect to the bulb filament 15. The reflector 40 turns within the housing 26, guided by the engagement of nuts 44 with the edge of the reflector.

The lamp 10 also includes a supplementary reflector or heat shield shown in FIG. 4 and designated generally by reference numeral 52. The supplementary reflector 52 includes a circular, concave reflecting plate 54 mounted on a pair of forwardly-extending arms 56 which are formed integrally with a transverse connecting member 58. The connecting member is in turn secured at its center to the top of a depending leg 60, to the bottom of which is secured a split ring 62. The split ring 62 is flexible, being formed of a strip of resilient metal such as spring steel, and being sized to be snapped around socket 12 and frictionally retained in mounted position, in the manner shown in FIGS. l-3. The leg 60 is of such size that the ring 62 may be positioned on socket 12 so as to locate the concave reflecting plate flush against the outer surface of the light bulb 14 and centered upon the filament 15 of said bulb. The leg 60 is also flexible to permit swivel movement of the supplementary reflector 52 so that the latter will align itself in flush abutment with the light bulb. As an alternative, the connecting member 58 may be swivelly 'mounted on leg 60. The reflecting plate 54 is of sufliciently large diameter to reflect substantially all of the forwardly-emitted rays of the bulb 14 in its area back to the reflector 40.

In practice, the reflector 40 is a parabolic reflector having a principal axis extending through the center of the reflector and indicated by the broken line 64 in FIG. 2. Located on the principal axis 64 is the focal point F of the reflector. It will be apparent that when the reflector 40 is located behind the bulb in an adjusted position in which the bulb is in registry with the central reflecting surface of the reflector, and with the bulb filament 15 located on the principal axis 64 at the focal point F, a concentrated beam of light will be produced. As the reflector 40 is turned within the housing 26 from this adjusted position, the distance between the bulb filament 15 and the focal point F will change solely because of the curvature of the reflector, and a reflecting surface of lesser diameter than the central surface of the reflector will move in registry with the bulb, thereby presenting a curved reflector surface area rather than a parabolic surface, and producing a wider, more diffused beam, as described in detail hereinbelow. It will be understood that while a parabolic reflector is preferred, the invention contemplates the use of other types of reflectors having varying surfaces which may be brought selectively into registry with the lamp bulb in order to obtain a concentrated spot as well as various light dispersion patterns. For example, the side portions of the parabolic reflector can be cut away to provide an oblong reflector to enable a smaller lamp unit to be made for portable use by auto mechanics, machine repair operators, and the like.

For insertion of a light bulb into the lamp, the socket 12 is turned about pivot 20 in the direction of the arrow 22 to the inoperative position shown in broken line in FIG. 2. The light bulb 14 is then screwed within the socket 12 in the usual manner so that proper contact with the socket terminals is made, and the socket 12 is then pivoted to the upstanding operative position shown in full line in FIG. 2. As will be presently explained, in establishing the operative position, the socket 12 is pivoted until the bulb filament 15 coincides as closely as possible with the focal point F of the reflector 40. It is to be understood that the term bulb filament is intended to include any light source in a bulb, such as horizontal, vertical, V-shaped, or pre-focussed wire filaments, as well as incandescent beads or gas spots.

In order to further adjust the lamp for positioning the bulb at the focal center of the reflector, the reflector housing 26 may be rotated relative to the socket supporting member 18, the sleeve 34 turning upon the threaded section 24 to raise or lower the bulb 14 relative to the reflector 40, so that the bulb may be positioned centrally within said reflector. In addition, in order to obtain the greatest efiiciency of the light bulb 14, it is highly desirable that the filament 15 be oriented in a plane perpendicular to the principal axis 64 of the refiector. Accordingly, after the bulb has been screwed into the socket 12, the reflector housing 26 may be turned until a position is reached in which the bulb filament 15 extends transversely to the principal axis of the reflector. Such a position is shown in FIG. 1.

It is to be understood that for obtaining an optimum concentration of light, the light bulb 14 should be of the clear glass type rather than of the frosted type. A frosted bulb will emit a diffused beam light pattern which will not be properly reflected to provided a concentrated spot.

After the light bulb 14 has been properly located in adjusted position as described above, the angular position of the reflector 40 may be adjusted. For this purpose, the clamping member 50 is loosened and the post 46 slid through slot 48 until the principle axis 64 of the reflector passes through the filament 15 and the focal point F coincides with the filament. This position can be determined by visual observation of the spot of light reflected by the lamp. Clamping member 50 is then tightened to retain the reflector 40 in adjusted position.

Reference may now be had to the schematic views of FIGS. 5 and 6 for a more detailed explanation of the operation of the present invention. Initially, it will be assumed that the supplementary reflector 52 is not utilized. As shown in FIG. 5, when the filament 15 (represented by a circle for purposes of illustration) is positioned at the focal point F of the reflector 40, the rays of light emitted radially from the filament 15 will strike the reflector 40 and will be reflected as rays parallel to the principal axis 64 to produce a spot of light 66 having a minimum area. In other words, when the source of light is positioned on the focal point of the parabolic reflector 40, the reflected rays of light will be parallel so as to produce the circular spot 66 of maximum concentration.

When it is desired to increase the area illuminated by the lamp, the clamping member 50 is loosened and moved to a selected position relative to the reflector housing 28, as indicated by the arrow 67 in FIG. 2, causing corresponding turning movement of the reflector 40 Within said housing. More specifically, as the post 46 is moved through the slot 48, the positions of the focal point F and of the principal axis 64 of reflector 40 will shift with respect to the source of light 15. The reflector is turned Within the housing until its central reflecting surface is out of registry with the rear of bulb filament 15 and an offset selected surface thereof is located behind and in registry with the bulb filament, as indicated in FIG. 6. In the position of FIG. 6, for example, the focal point F is located above and to one side of filament 15 and a curved surface area of lesser diameter than the center of the reflector is located behind the bulb to act as a curved mirrored reflector plate.

Due to the curvature of the parabolic reflector 40, it will now be obvious that not all the rays which are reflected by the reflector will be parallel to each other. Most of the rays emitted by the filament 15 will strike the surfaces of the reflector with varying angles of incidence, resulting in diverging reflected rays and a wide spot indicated at 68 of FIG. 6. Accordingly, the area of the spot illuminated by the light beam will be substantially greater than the area illuminated by the light beam when the source of light is positioned at the focal point F of the reflector 40. Hence, simply by moving the reflector 40 relative to the source of light 15 by means of the clamping member 50 and the post 46, the area which is illuminated by the lamp 10 of the present invention may be selectively varied in accordance with the dimensions of the object which is to be illuminated.

It is to be noted that as the area of the light beam is dispersed, the irradiance of the light will correspondingly decrease. Hence, not only does the lamp 10 of the present invention provide a means for increasing the area of a light beam from a minimum area, but it also produces a lower density light, thereby decreasing the glare produced by the beam.

When the source of light is positioned at the focal point F of the reflector 40 it is to be noted that those rays of light which are not reflected (i.e. the rays which pass directly outwardly from the source 15) will be at random angles with respect to the paraxial rays. In order to eliminate these randomly oriented light beams and thereby increase the irradiance of the lamp 10, the sup plementary reflector plate 54 may be utilized, as shown in FIG. 7. The supplementary reflector 52 is positioned so that the reflecting plate 54 is in front of and aligned with the filament 15 of the light bulb 14. Accordingly, those rays such as light rays 70 which are directed forwardly from the filament 15 will impinge on the supplementary reflector plate 54 and will be reflected back to the reflector 40. Thus, these rays will likewise be reflected from the reflector 40 as rays which are parallel to the principal axis of the reflector thereby to increase the illumination produced by the light beam and eliminate the fuzziness or fringe area which may otherwise exist around the periphery of the area 66. The supplementary reflector also acts as a shield to deflect direct heat radiation from the filament.

Accordingly, a lamp has been disclosed which produces a light beam having a variable area in accordance with the requirements of the user, which is simple in construction and reliable in operation.

While a preferred embodiment of the invention has been shown and described herein it will be obvious that numerous omissions, changes and additions may be made in such embodiment without departing from the spirit and scope of the present invention.

What is claimed is:

1. A lamp comprising socket means for mounting a light bulb having a light source, a reflector housing, means connecting said reflector housing with said socket means for positioning the light bulb centrally and immovably within the reflector housing, a parabolic reflector having a preselected focal point and an arcuate central reflecting surface shaped to reflect the light of said bulb in a con centrated beam of parallel rays when the light source of the light bulb is located at said focal point, and mounting means movably mounting said reflector in said housing relative to said immovable light bulb for movement around said light bulb between a first position in which the central reflecting surface is located behind and in registry with the bulb and said bulb light source coincides with the focal point of the reflector, and provides a concentrated beam of light with parallel rays, and variable positions in which said focal point is spaced from said bulb light source and portions of the reflector of varying curvatures dilfering from the curvature of said central reflecting surface are located behind and in registry with said bulb, to produce a wider and more diffused beam.

2.. A lamp according to claim 1, in which said mounting means mounts said reflector for revolving movement within said housing about said light bulb.

3. A lamp according to claim 2, wherein said mounting means includes opposed, inwardly-directed guide members fixed upon the inner surface of said reflector housing, said guide members being located to engage diametrically opposed edges of said reflector for sliding movement of said edges therealong as said reflector is turned Within said housing.

4. A lamp according to claim 3, in which said mounting means includes an elongated slot in said reflector housing, a post fixed to said reflector and extending through said elongated slot for turning movement of said reflector within said housing when said post is selectively moved along said slot, and clamping means received on the end of said post and adapted to frictionally engage said reflector housing to maintain said reflector in adjusted position relative to said bulb light source.

5. A lamp according to claim 1, in which said connecting means includes a first threaded member connected to said lamp socket means, and a second threaded member connected to said reflector housing and in threaded engagement with said first threaded member, whereby relative movement of said first and second threaded members causes movement of said reflector housing relative to said lamp socket means and the inserted light bulb, and in a direction substantially longitudinal of the latter.

connecting said lamp socket means with said first threaded member for selective. movement of the bulb received in lamp socket means toward'and away from the inner surface of said reflector.

7. A lamp according to claim'l, which also includes "a supplementary reflector connected to said lamp socket means and positioned in-frontof said lightbulb to reflect forwardly-emitted rays from said bulb light source back "8 'A lamp according to claim 7, in which said supple- "mentary reflector includes a concave reflecting plate, and bracket means connected to said reflecting plate and engageable with said socket means to rernovably mount said supplementary reflector on said lamp socket means in a position in which said reflecting plate is in flush abutment with the front surface of said light bulb.

- I "UNITED 1,638,716 2,666,194

References Cited STATES PATENTS '8/1927 Surles 24010.69 XR 1/1954 He6hl6r 24044.1 XR 7/1968 Neely et, 1. 240-84 XR 7/1922 Humiston 240 10.69 8/1922 Wood 240-44.l 10/1922 Stimson 24()10.69 1/1924 OConnor' 24044.1 6/1926 Reymond 24044.1 12/1934 Benford 24044 XR 2/1938 Bardwell et al. 240-44 FOREIGN PATENTS 12/1908 England.

NORTON ANSHER, Primary Examiner R. P. GREINER, Assistant Examiner