This invention relates to ellipsoidal stage lights and so-called linear moving patterns for projecting patterns from such lights. More particularly, a linear moving pattern attachment is disclosed which enables projection of a pattern having linear motion from such ellipsoidal stage lights.
Ellipsoidal stage lights are old and well known. Specifically, these lights get their name from the ellipsoidal shape of their reflecting mirrors and their use of the two ellipsoidal foci. A brief explanation of this prior art technology is in order.
An ellipse drawn on a plane has a major axis and a minor axis. The ellipse is elongate in the direction of the major axis and defines two foci along this major axis. By rotating the ellipse, one obtains an ellipsoid. By cutting off one end of the ellipsoid beyond the second focus, the interior optics of an ellipsoidal stage light can be understood.
Specifically, the reflecting mirror of an ellipsoidal stage light is shaped interior of the ellipsoid about one focus of the ellipsoid. The lamp is placed at this focus. When the lamp is energized, light is received and reflected to the remaining second focus of the ellipsoid.
Naturally, projection to a target, such as a stage must occur. In an ellipsoidal light, the ellipsoid is cut or truncated at the end opposite the reflector, usually slightly beyond the secondary focus. Objective lenses of various kinds and designs are placed in the light beyond the second focus. A beam is then projected by the objective lenses from the light.
In a conventional ellipsoidal stage light, shutters are manipulated with respect to the second focus to trim the edges of light projected by the light. Ellipsoidal lights are unique in this ability to use shutters to trim the edges of their projected image; they are simple, inexpensive, and capable of precise edge control of their projected beams in their stage lighting function.
In stage or scene light design, it is sometimes necessary to project patterns. It was from this necessity that the so-called xe2x80x9cgoboxe2x80x9d was developed for use with ellipsoidal stage lights.
Very simply stated, ellipsoidal lights are usually provided with an iris slot at the vicinity of the second focus. By placing a pattern (sometimes called a xe2x80x9cgoboxe2x80x9d), typically in the form of a patterned sheet of metal, glass or temperature resistant film into the iris slot adjacent the second focus of the ellipsoidal light, a corresponding pattern is projected as a light image, usually towards a stage.
Moving patterns have been projected from such ellipsoidal lights. Unfortunately, the space available at the iris slot in the vicinity of the second focus is extremely limited. To date, only circularly moving patterns have been used with ellipsoidal lights. An example of a gobo having circularly rotating mounted patterns placed in the iris slot of an ellipsoidal light is sold under the trademark GAM TwinSpin II(trademark) of Gam Products Inc. of Hollywood, Calif. In this particular gobo design, circular patterns rotate about the major axis of ellipsoidal light in the vicinity of the second focus. With the GAM TwinSpin II(trademark), it is possible to have two patterns rotate in opposite directions.
Unfortunately, circularly rotating gobos produce circularly rotating patterns. While such circularly rotating patterns can be occasionally used in light design, they are out of step with the real worldxe2x80x94where most patterns travel either horizontallyxe2x80x94as in the case of cloudsxe2x80x94or verticallyxe2x80x94as in the case of rain (down) or fire (up).
To solve this problem for the lighting designer, there has been developed a product known as a projector. An example of such a projector is the GAM Scene Machine sold by Gam Products Inc. of Hollywood, Calif. In short, this projector uses the principle of a light with two foci to project scenes, such as clouds, rain, snow, and fire. Just as in the case of the ellipsoidal light, in this rather expensive dedicated projection instrument, the image to be projected is placed at the second focus of a two focal plane system.
When linearly moving images are desired in such projectors, it is known to use endless pattern loops of continuously rotating metal, or film to project such images. The endless pattern loops typically have a drive roller on one side the projector, a return roller on the opposite side of the projector, and two planar runs of projection material extending in the vicinity of the projectors second focus. Since such projectors are specially designed instruments, space in such instruments is generally of no concern. As a consequence, a relatively large projection rotator is used.
By registering one or the other of these planar linearly moving runs of projection material to the second focus of the projector, two separate effects occur. First, the linearly moving run of projection material coincident to the secondary focus has its linearly moving pattern projected by the projector. A corresponding linearly moving pattern of light is projected. Second, the run of projection material not coincident to the secondary focus acts only to attenuate or modulate the light projected. It primarily effects the brightness (or amplitude) of the projected light. Since it is out of the plane of the secondary focus, its image does not project. From such projectors, it is known to project light images of rain, snow, fire, clouds and the like.
Unfortunately, such projectors are large, specialty instruments. They require special mounting, with their own lighting design and operation techniques.
In what follows, we disclose a linear moving pattern for projecting linear motion that is adapted to the narrow confines of a conventional ellipsoidal stage light. In making this adaptation, we set forth the problem to be solved, as well as its solution. The reader will understand that the discovery of the problem to be solved can constitute invention. Therefore, in so far as the prior art does not set forth the problem that we solve, invention is claimed to that aspect.
A gobo having linear motion pattern projection is inserted to the narrow iris slot of a conventional ellipsoidal stage light. The linear moving pattern includes a housing, a drive roller and motor, a return roller, and an endless pattern loop. The housing has a narrowed end for protruding into the instrument at the iris slot and holding the return roller on one side of the light. The housing has a broad slot end for mounting outside of the ellipsoidal stage light for holding the drive roller and motor at the other side of the light. The broad slot end of the housing has two spring-biased hinged clamps for clamping the gobo into a single unitary linear moving pattern iris insert. A motor clamp holds the drive roller and motor in place. A pattern clamp tensions and dimensions the endless pattern loop for extension into and out of the iris slot of the ellipsoidal light. In assembly, the endless pattern loop is first threaded to the return roller and the return roller mounted to the narrow end of the housing. Second, the drive roller and motor is threaded to the endless pattern loop, placed into the housing at the broad slot end, and locked into place by the motor clamp. Third, the tension clamp is dropped over the endless pattern loop to dimension and tension the endless pattern loop at two parallel and linear runs on opposite sides of the iris slot between the drive roller and return roller. Fourth, the unitary linear moving pattern iris insert is inserted to ellipsoidal stage lighting instrument at the iris slot for operation. In operation, the motor rotates the drive roller relative to the housing to rotate the endless pattern loop. One linear run of the endless loop pattern is registered near the second focus of the instrument to project the desired linear pattern while the remaining linear run of the endless loop pattern attenuates the projected image. There results the ability to provide locally focused and conventional ellipsoidal stage lights with linearly moving projected patterns.
It will be understood that one or the other linear runs of the endless pattern loop can be at the focal plane. In this way apparently linear movement of the pattern will be changed (reversed).
An advantage of this apparatus and method is that it enables the lighting designer to easily place linearly moving projected patterns wherever an ellipsoidal light can be focused to a light design area. The bulk, added expenses and design inconvenience of specially designed projectors are not required for local linearly moving image projection.
An additional advantage of this apparatus is that the linear moving pattern can be easily interchanged among the ellipsoidal lights of a design. The linear moving pattern can be removable between ellipsoidal instruments until an optimal location is determined.