Illumination – Light source and modifier – Including reflector
Patent
1989-11-03
1992-01-21
Lazarus, Ira S.
Illumination
Light source and modifier
Including reflector
362373, 362374, 362294, 362280, 362455, F21V 700
Patent
active
050832530
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to improvements in lighting units and in particular to lighting units of the type used with video cameras.
Lighting units for use with video recorders are known, however, such prior art lighting units have a number of problems. First, in the known type of lighting units the light source is movable relative to a focussing lens to provide a light beam of either spotlight or floodlight quality. This construction of light has the disadvantage that it requires a two or three lens system to provide the necessary floodlight/spotlight characteristic light beams. In addition, this known light unit is complicated in construction.
A further disadvantage of the prior art lighting units is that they generally use either a parabolic or an elliptical type of reflector. The parabolic type reflector has the disadvantage that the light beam cannot be fully controlled by the lens system and hot spots in the central area of the light beam often require a diffuser to evenly distribute the light beam. The elliptical type reflector has the disadvantage that direct light emission from the filament of the bulb is reduced and inefficient because the bulb is positioned horizontally and with the glass tip facing forwardly thus interfering with direct light flow from the filament. Further, because of the proximity of the lamp filament to the rear of the reflector, and since the light bulb must be inserted through an aperture in the rear of the reflector, this results in considerable loss of reflective area and thus efficiency.
Accordingly, it is an object of the present invention to provide a lighting unit which is portable and which also may be easily attached to a video camera. This requires a lighting unit which is light in weight and compact in size. As a matter of fact, the lighting unit should provide floodlight and spotlight with high efficiency and high optical qualities.
According to the invention, the solution to this objective is provided by a lighting unit comprising a housing including a reflector mounted within the housing, a removable light source fixed within the housing and disposed within the region of the reflector, and a focusing lens movably mounted on the housing forwardly of the light source, the lens at least movable between positions to provide floodlight and spotlight light beams. In a preferred embodiment according to the invention, the reflector includes a part-spherical member and is disposed slightly rearwardly of the light source. A major advantage of the invention is that it provides an extremely compact lighting unit with good beam control and good efficiency due to the reflector having a part-spherical component. The compactness of such a lighting unit is a major advance with potential wide usage. The lighting unit is portable, compact and readily attachable to a video camera.
Further advantageous embodiments of the invention form the subject matter of several subclaims.
An embodiment of the invention will now be described by way of example with reference to the accompanying drawings in which:
FIG. 1 is a front perspective view of a lighting unit according to the invention,
FIG. 2 is a rear perspective view of the lighting unit of FIG. 1,
FIGS. 3 and 4 are front and rear perspective views of the lighting unit of FIG. 1 with the focussing lens in its forward position,
FIG. 5 is a diagrammatic sectional view of the reflector, light source and focussing lens,
FIG. 6 is a perspective view of the light source holder,
FIG. 7 is a cross-sectional view taken along the line VII--VII in FIG. 2 of the sub-housing holding the focussing lens,
FIG. 8 is a rear end view, partially in cross-section, of the sub-housing as shown in FIG. 7,
FIG. 9 is a diagrammatic view of the locking means for the sub-housing, and
FIGS. 10 and 11 are front and underneath perspective views of the fan unit.
Referring now to the drawings wherein similar numerals have been used to indicate like parts, there is shown therein a lighting unit generally indicated at 10 according to the invention. The lighting unit
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Cox D. M.
Lazarus Ira S.
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