Shutter lock for specialized lighting fixtures

A specialized lighting fixture, such as a framing projector provided with a plurality of adjustable framing shutters, is modified to incorporate a pair of locking rings, surrounding the body of the lighting fixture and positioned on opposite sides of outwardly projecting portions of the framing shutters. After initial adjustment of the framing shutters has been completed, the locking rings are tightly compressed together, as by locking screws positioned between adjacent pairs of framing shutters, to lock the shutters in position against unintended dislodgment. For lighting fixtures of non-uniform shape, the locking rings may be made in two parts, preferably hinged together, which are secured together after being positioned on the housing of the lighting fixture. The locking rings are particularly adapted for retrofit installation on lighting fixtures of existing design.

BACKGROUND OF INVENTION

For theatrical lighting, and for various applications of specialized commercial lighting, it is a common practice to utilize special lighting fixtures occasionally track mounted but more frequently mounted in other ways, which can be aimed and focused on a particular area. Such lighting fixtures typically incorporate a relatively high intensity light source, one or more focusing lenses, and provisions to accommodate accessory cartridges with filters, etc. for achieving a variety of specific lighting effects. Many such lighting fixtures also incorporate adjustable framing shutters that are movable to positions partially blocking and shaping the light source. Typically, there are a plurality of such shutters, for example four, spaced around the circumference around the lighting fixture. These are adapted to be manually adjusted inward and outward with respect to the center line of the lighting fixture, and also to be tilted, all for the purpose of enabling the light discharged from the fixture to be rather precisely shaped and confined, such that it may be directed with a considerable degree of precision at a particular object area to be illuminated.

Framing shutters for lighting fixtures of the type described above advantageously can include a shutter panel, which projects more or less radially into the interior of the lamp housing. The shutter is formed of relatively thin sheet metal and typically has an integral extension arm projecting generally radially outward of the lamp housing and mounting a handle at its outer end. Friction elements act on the shutter plates, tending to hold them in any position in which they are set.

In a typical setup operation, a lighting technician will aim and focus the lighting fixture and, in conjunction therewith, will shift the framing shutters radially inward or outward, and perhaps tilt one or more of them in their planes, with the end result that the focused beam is both confined and shaped in a manner calculated to achieve a desired effect.

In many, if not most, situations, once a lighting fixture has been aimed, focused and the light beam suitably shaped and confined with the framing shutters, it may be expected to remain in that setting for an extended period of time (e.g., weeks or months). In many cases, however, the lighting fixture may be subject to bumping, jarring, vibration, etc., which can have the effect of shifting one or more of the framing shutters from its originally adjusted position. This can occur over a period of time, as where the fixture may be subject to a vibrational environment, or it may happen more abruptly if a handle of a framing shutter is accidentally bumped.

DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

In accordance with the present invention, a simplified and inexpensive positive locking arrangement is provided for the framing shutters of a specialized lighting fixture, such that once the framing shutters have been adjusted to suit the installing artist or technician, the framing shutters can be effectively permanently locked in their adjusted positions until intentionally moved after releasing the shutter locking means.

In its basic form, the shutter lock device of the invention comprises a pair of ring-like elements that are received over the exterior of the lamp housing, in a close fitting relation thereto, completely or substantially completely surrounding the lamp housing, with one ring being positioned on each side of outwardly projecting portions of the framing shutters. The two ring-like elements, sometimes referred to herein as locking rings, are secured together at a plurality of circumferentially spaced points by means of locking screws, by which significant clamping pressure may be brought to bear between the two locking rings. For the initial adjustment of the framing shutters, the locking rings are released by loosening the screws, to provide a relatively loose fitting relation with the framing shutters. However, once the shutters have been positioned to the satisfaction of the technician, the locking screws are tightened, and the locking rings bear against the framing shutters with considerable force to securely lock them in their adjusted positions.

The shutter lock feature of the present invention can be incorporated into a specialized lighting fixture of the type described at a minimum additional cost, while solving a long-standing problem with respect to unintended loss of shutter adjustment over time from vibration and other causes. In addition, the device of the invention can easily be installed as a retrofit on existing fixtures, in order to upgrade usefulness of such fixtures.

In its simplest form, the shutter lock is simply two circular rings joined at multiple points by a plurality of circumferentially spaced locking screws. Where the shape of the lamp housing and/or the production procedures of the lighting fixture are appropriate, a pair of closed circular rings may be installed by sliding them over the lamp housing to positions on opposite sides of the framing shutters. Otherwise, the locking rings may be formed as semi-circular pairs, to accommodate retrofit installations. In such a case, the locking screws may serve a dual function, providing a means for joining the ring parts, as well as performing their regular clamping/locking functions.

For a more complete understanding of the above and other features and advantages of the invention, reference should be made to the following detailed description of preferred embodiments of the invention, and to the accompanying drawings.

DESCRIPTION OF PREFERRED EMBODIMENTS

Referring now to the drawings, the reference numeral10designates generally a specialized lighting fixture for theatrical or commercial lighting such as, for example, the BP75 framing projector as manufactured by Lighting Services, Inc., of Stony Point, N.Y. The illustrated fixture is specifically intended for track mounting, and therefore includes a track mount housing11from which extends a support bracket12. The bracket12is pivotally mounted at13to the housing11, for rotation about a vertical axis, and is formed in upper and lower parts14,15pivoted at16for rotational adjustment about a horizontal axis.

In the illustrated form of the invention, the main housing17of the lighting fixture comprises front and back portions18,19. The back portion19, which is attached to the lower bracket elements15, houses a light source (not shown) in the back portion thereof, a plurality of framing shutters20in front of the light source, and an accessory28which is removably received at the front of the housing portion19. The front barrel portion18of the lamp housing may contain focusing lenses.

With reference toFIGS. 3 and 4, the rear housing portion19is formed with a plurality of circumferential slots21for the reception of a plurality of the framing shutters20. In the illustrated structure, there are four framing shutters20, arranged generally at right angles with respect to each other. The framing shutters are formed of sections of flat, relatively thin sheet metal blades22which are shaped to provide an outwardly extending stem portion23, and a somewhat triangularly shaped internal portion24. The shutter blades22are frictionally gripped by internal flanges25,26(FIG. 3) which allow the shutter blades to be manipulated radially of the housing19, and also to be tilted, if desired. Once adjusted, the shutter blades22are retained in their adjusted positions by the frictional grip of the flanges25,26. Each of the shutters is provided with an external handle portion27which allows it to be gripped for accomplishing the desired adjusting motions.

In a typical case, the lighting fixture initially may be set up on location with the intent that it remain in its adjusted condition for a considerable period of time. However, the framing shutters20may be subject to unintended dislocation over time, as through vibration, being accidentally bumped, etc. In accordance with the present invention, such dislocations are avoided by incorporating into the lamp structure, either in the initial production or as a retrofit accessory, a positive locking means for reliably retaining the framing shutters in their preadjusted positions until intentionally released for readjustment.

In the illustrated form of the invention, the shutter locking means advantageously comprises a pair of locking rings30,31(FIGS. 5 and 6) which are joined together at a plurality of circumferentially spaced points by means of locking screws32. Preferably, the locking rings30,31are shaped and sized to conform closely to the exterior of the rear lamp housing19. In the illustrated case, the housing13is circular, as are the locking rings30,31. The rings30,31can be installed by first removing the framing shutters20from the slots21in which they are normally retained and sliding the rings30,31over the lamp housing to position one ring on each side of the shutter slots21. The framing shutters are then re-inserted in their slots, between the shutter plates22, with the locking screws loosened or removed.

When the locking screws32are in a loosened condition, the framing shutters20may be manipulated and adjusted in the usual manner. Once the shutters have been adjusted to the satisfaction of the technician, however, the locking screws32are tightened to securely lock the shutters in their as-adjusted positions until such time as the locking rings are released. The adjusted positions of the framing shutters will not be affected by typical vibration, accidental jostling, etc.

In the specifically illustrated embodiment of the invention, both the lamp housing19and the locking rings30,31are of circular configuration. However, if the lamp housing is of a non-circular configuration, or elements incorporated with the lamp housing must be accommodated, the clamping rings can be formed of an appropriate shape to accommodate other configurations. Additionally, it is not necessary that the locking rings make contact with the lamp housing throughout its entire periphery, but only that there is contact at enough positions to locate the locking rings relative to the housing portion19.

In the illustrated form of the invention, it has been found sufficient to utilize four locking screws32spaced such that, in the installed arrangement, there is a locking screw positioned between each adjacent pair of framing shutters20, as reflected inFIG. 4. In the contemplated forms of the invention, there is sufficient stiffness in the material of the clamping rings30,31to enable fully effective locking action to be achieved using a single screw between each pair of framing shutters. For example, for a framing projector of around three inches in diameter, clamping rings formed of steel plate, of about 3/32 inch in thickness, are suitable. For projectors of larger size, the clamping rings of correspondingly heavier construction may be appropriate.

In some instances, the configuration of the lamp housing17may not readily accommodate the reception of locking rings of a closed configuration for a retrofit installation of a shutter locking facility. For such cases, the locking rings may be made in two parts (e.g., semi-circular instead of circular in case of the locking rings shown inFIGS. 5 and 6) with certain of the locking screws32being utilized in a dual capacity, as clamping/locking screws and also to join two half sections together after they are positioned around the lamp housing.

The device of the invention results in a significant improvement in the long-term operability of a framing projector or the like employing adjustable framing shutters. Although adding minimally to the cost of the unit, the shutter lock feature enables the unit to be retained in its initially adjusted condition for as long as needed, without concern for unintended repositioning of the framing shutters over time.

It should be understood, of course, that the specific forms of the invention herein illustrated and described are intended to be representative only, as certain changes may be made therein without departing from the clear teachings of the disclosure. Accordingly, reference should be made to the following appended claims in determining the full scope of the invention.