Illumination – Light source and modifier – Adjustable or repositionable light source or light source...
Reexamination Certificate
1997-11-21
2001-09-18
O'Shea, Sandra (Department: 2875)
Illumination
Light source and modifier
Adjustable or repositionable light source or light source...
C362S289000, C362S306000
Reexamination Certificate
active
06290373
ABSTRACT:
BACKGROUND OF THE INVENTION
(a) Field of Art
This invention relates to a light fixture which is adapted to accommodate either tungsten filament and gas discharge light bulbs in an adjustable carriage to permit an operator to adjust the focus of the light and to switch bulbs to illuminate a scene, such as the scene of a motion picture film, with different lighting effects.
(b) Prior Art
It is known in the prior art to use both tungsten filament and gas discharge lights to illuminate large areas with either spot or flood lighting. It is also known that tungsten filament bulbs and gas discharge bulbs emit light of different temperature which create different lighting effects. It is within the ordinary skill of a person who constructs light fixtures to make a socket to receive and power both a tungsten filament bulb or a gas discharge bulb.
It is known that light fixtures may be constructed to permit a light bulb to move with respect to a parabolic light reflector to adjust the focus of the light. In this manner one may adjust between spot and flood lighting. One way of focussing a light has a carriage that supports a socket and a bulb to move a bulb linearly with respect to the reflector. This type of mechanism has been used with either gas discharge and tungsten filament light bulbs, but no one such mechanism has been developed for use with both types of bulbs.
Instead, the common practice is that tungsten filament lights are mounted in one type of fixture and gas discharge bulbs are mounted in a different type of fixture and the fixtures are interchanged from time to time while illuminating a scene as is appropriate to the lighting requirement. Specific fixtures have been developed for tungsten filament and gas discharge bulbs, in part, because the source of the light in a tungsten filament bulb is at a different linear position than it would be found in a gas discharge bulb; thus each type of bulb has a different longitudinal range of focus with respect to a reflector in a fixture. Consequently, an operator would have difficulty controlling a servo mechanism to change from spot to flood lighting as bulbs were changed, because the carriage would have to be controlled within different ranges.
The capital cost of having special light fixtures for each type of light bulb may be reduced with the present invention.
GENERAL DESCRIPTION OF THE INVENTION
It is an object of the present invention to provide a light fixture having a focusing apparatus which may be used for either gas discharge or tungsten filament bulbs.
The present invention is a light fixture comprising a reflector to reflect light to illuminate a scene; a socket to receive and to hold either a tungsten filament bulb or a gas discharge bulb; a power source to provide electrical power to said socket to illuminate either a gas discharge or tungsten filament bulb; a carriage holding said socket in a position where a light bulb in the socket will extend forwardly of said reflector, said carriage being mounted on tracks to slide linearly back and forth with respect to said reflector; a drive means under the control of an operator to move the carriage through a range of linear motion; an adjustable connector linking the drive means to the carriage to permit an operator to adjust the position of the range of motion of the carriage to accommodate different types of bulbs.
The socket is mounted in a carriage which in turn is mounted to slide upon tracks and to permit the bulb to move linearly to and fro with respect to the reflector to adjust the light emanating from the light fixture between spot and flood lighting. The tracks are mounted between a rear wall and a front wall of a box which surrounds and protects the carriage. The light bulb extends through a hole in the front wall forwardly of a base of the reflector and guide means, comprising springs extending from a ring surround the bulb to help support it in the socket as the carriage moves.
In a preferred embodiment disclosed hereafter the drive means comprises a servo mechanism actuator, an arm extending from said actuator to a crank handle, a crank shaft extending through a side wall of the box enclosing the carriage, a radial arm connected to rotate in response to movement of the crank shaft, a rod connected to a distal end of said radial arm connected to an adjustable connector on the carriage. It will be obvious to one skilled in the art that other linkages between an actuator and the adjustable connector on the carriage would be possible without departing from the invention. For example, a more direct linkage could be established to eliminate some elements or some of the elements could be replaced with flexible or coiled wire elements.
In a preferred embodiment disclosed hereafter the adjustable connector comprises a pair of flanges extending outwardly from the carriage, a threaded shaft mounted to turn between said flanges in a non-threaded connection, a threaded block mounted in a threaded connection on said shaft and a lug on said block connected to the dive means; said threaded shaft being capped by a head to receive a screwdriver to permit to turn the threaded shaft to adjust the position of block between the said flanges thus altering the range of motion of the carriage in response to the drive means. Again the particular construction of this embodiment might be altered in ways obvious to one skilled in the art without departing from the principle of this invention. For example, the threaded shaft could be replaced by any mechanical equivalent that would obtain the function of permitting a linear change in the relationship of the connector to the drive means such as a stepped rod that would engage at different positions located on the carriage.
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Dwight Brian
Dwight David
Duane Morris & Heckscher LLP
Dwight Crane Rentals Ltd.
Negron Ismael
O'Shea Sandra
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