Lighting Device

Abstract

A lighting unit includes a light source and a curved reflector. The lighting unit provides a rectangular light pattern which illuminates a predetermined area with the direct light from the light source and the reflected light from the reflector.

Description

BACKGROUND OF THE INVENTION

Lighting units with reflectors have been used previously to provide various light patterns. A light pattern defines the shape of the area illuminated by the light emanating from the lighting unit; this light is a combination of light direct from the light source and light reflected from the reflector.

Reflectors increase the intensity of the light being directed from the lighting unit and curved reflectors act to control the direction of the reflected light rays and distribute the reflected light within the light pattern. The distribution of the reflected light within the light pattern depends on the geometric characteristics of the curved reflector and the positioning of the light source relative to the reflector.

In the past it has been common to direct the reflected light rays parallel from the reflective surface of the reflector or radially inward from the reflective surface. When the reflected light rays are parallel, the area within the light pattern in which direct light and reflected light are combined is substantially limited to the aperture of the reflector. When the light rays are reflected radially inward, the area within the light pattern of combined direct light and reflected light is smaller than the reflector aperture and decreases as the light unit is moved closer to the area to be illuminated. Moreover, since the intensity of the direct light is normally greater near the center of the light pattern because the edges of the light pattern are farther from the light source, when the reflected light rays are directed parallel or radially inward the intensity of the combined light will also be non-uniform and greater at the center of the light pattern.

In the present invention, it is desirable that the intensity of the light throughout the light pattern be substantially uniform. It is also desirable that the aperture of the reflector be relatively small with respect to the area of the light pattern provided when the lighting unit is maintained in close proximity to the area to be illuminated. A further characteristic of this invention which is again desirable is that the light pattern provided be rectangular.

A lighting unit with the above characteristics has been found to be particularly useful in the illumination of music sheets when they are placed on a music rest such as those found on a piano or organ. Moreover, the close proximity of the light to the music sheet and the defined rectangular light pattern produced minimizes any stray light not falling on the area to be illuminated which might interfere with the work of the player or other players or detract from an audience's enjoyment of the music. Also, the relatively small size of the reflector aperture with respect to the light pattern produced provides for a small lighting unit which will not interfere with the audience's visibility of the player or obstruct the player's view of the music or of a conductor. Furthermore, because the overall size of the lighting unit is relatively small, it can be mounted on the music rest rather than on the body of the instrument to provide a more versatile and adaptable unit.

To accomplish this, the present lighting unit includes a reflector and a light source. The reflector and the light source are housed within a lamp housing which has a rectangular opening or aperture which causes the direct light from the light source to be maintained within a rectangular area. The reflector has a curved reflective surface which defines a portion of an elliptic cylinder or elliptic channel. Such a curved reflective surface maintains the reflected light generally within the rectangular area formed by the direct light and the area formed is large relative to the aperture of the reflector. The geometric characteristics of the surface also are such that more of the reflected light is distributed toward the ends of the rectangular area than toward the middle of the rectangular area. The light source is positioned along the major axis of the elliptic curve in such a manner to increase the amount of reflected light distributed toward the ends. Thus, the intensity of the reflected light is greater at the ends of the rectangular area and the intensity of the direct light is greater at the middle of the rectangular area to provide a combined light of substantially uniform intensity throughout the rectangular area.

The lamp housing is connected to a transformer by a flexible arm or conduit to allow for adjustment of the distance between the aperture of the reflector and the area to be illuminated. A clip member connected to the transformer releasably secures the lighting unit to a music rest or the like.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view illustrating the lighting unit mounted on the music rest of a piano.

FIG. 2 is a side elevation of the lighting unit secured to a music rest.

FIG. 3 is a front view of the lamp housing.

FIG. 4 is a top view of the lamp housing in section.

FIG. 5 is a diagrammatic view of the curve of the reflective surface and the light source illustrating the reflection of the light rays from the reflective surface.

As best seen in Figure 2, the lighting unit, generally designated 10, includes a conventional transformer which is housed within a transformer housing 11. An electrical power cord 12 connects the transformer to a suitable power source, not shown, and a conventional switch (not shown) connected to power cord 12 at a convenient location actuates the lighting unit. The transformer allows the voltage provided from the power source to be adjusted. A flexible clip member 14 secured at one end to the transformer housing 11 mounts the lighting unit 10 to a sheet rest 21 or the like positioned between the clip member 14 and the transformer housing 11. A flexible conduit or arm 15 connects the transformer housing 16. Mounted within the lamp housing 16 is a lamp 17 and a curved reflector 18. The lamp 17 is mounted within a socket 19 which is positioned at the vertex of the curved reflector 18. Electrical conductors carried within the flexible conduit or arm 15 electrically connect the transformer and the lamp 17. The lamp housing 16 is provided with a rectangular opening or aperture 20 which defines the light pattern formed by the light emanating directly from the lamp 17.

Referring to Figure 5, the curved reflector 18 necessary to provide a light pattern which is large relative to the aperture of the reflector, includes a curved reflective surface 22 which defines a portion of an elliptic cylinder or an elliptic channel. The elliptic curve 22 includes a major axis 24, a vertex 25 and a focal point 26.

The aperture of the reflector 18, generally designated 28, coincides with the opening or aperture 20 of the lamp housing 16 and is a plane defined by the two parallel ends 29 and 30 of the reflective surface 22, the imaginary line connecting the upper corners 31 and 32 of the ends 29 and 30, respectively, and the imaginary line connecting the lower corners 33 and 34 of the ends 29 and 30, respectively. Upper and lower walls, 35 and 36, which cover the ends of the elliptic channel are formed by the lamp housing 16.

The lamp 17 includes a light source of filament 37 and a glass bulb 38. Preferably, the end of the glass bulb 38 is frosted to provide a light pattern of more uniform intensity by decreasing the direct light radiated outwardly along the axis 24, i.e., decreasing the light intensity in the center of the radiation pattern. In order to increase the amount of light directed toward the lengthwise edges of the rectangular light pattern, the filament or light source 37 is positioned on the major axis of the curve 23 beyond the focal point 26 and between the focal point 26 and the aperture 28. Preferably, the filament or light source 37 is positioned perpendicular to the upper and lower surfaces 35 and 36 and is as small as possible in proportion to the size of the reflector so as to improve light control of the lighting unit and reduce stray light as well as improving the efficiency of the lighting unit.

An example of one embodiment particularly desirable for illuminating piano sheet music includes a No. 1855 lamp. This lamp has a desirable filament size and is rated at 6.3 volts, 0.8 amps, has a 3,000 hour lamp life and provides approximately 3.6 candle power. Since 3.6 candle power is normally inadequate, the applied voltage is increased by the transformer to approximately 8 volts which provides approximately 8.0 candle power and an average lamp life expectancy of approximately 150 hours. The dimensions of the elliptical reflector may be varied, to provide various rectangular light patterns. However, a reflector when using the No. 1855 lamp which is acceptable, is one approximately 1.125 inches in depth, 2 inches in width and 0.625 inches in thickness. While the exact reflector dimensions are not critical, the reflector configuration and proportions should be maintained proportionally to the lamp filament size. In this embodiment, the light spread between the ends 29 and 30 of the reflective surface is 138.degree. and the light spread between the front edges of the walls 35 and 36 is 90.degree. .

In operation the lighting unit 10 is mounted to a sheet rest or similar member by the clip member 14. The electrical power cord 12 is connected to a suitable power source which normally will have electrical power voltage of 115 volts a.c. which is reduced to the desired voltage a.c. by the transformer. The light source is actuated by the switch and the flexible arm 15 is adjusted until substantially all the light rays amanating from the lighting unit fall within the area desired to be illuminated.

This lighting unit illuminates a predetermined area relatively uniform with sufficient intensity. The light pattern provided by the lighting unit is quite large relative to the aperture of the reflector to allow the lamp housing and light source to be positioned close to the area to be illuminated to avoid distraction because of the light emanating from the unit and allows the lamp housing of the lighting unit to be relatively small in order not to interfere with the area to be illuminated.

Claims

I claim:

1. A lighting device to provide a rectangular light pattern comprising:

a lamp having a bulb with a filament therein;

means to electrically connect said lamp to a suitable power source;

an elliptic channel reflector having a focal point and an aperture;

a lamp housing, said lamp and said reflector being positioned within said housing, said housing being provided with a rectangular opening defining the light pattern formed by direct light emanating from said lamp;

said elliptic reflector having geometric characteristics which are such that the light reflected from said reflector falls within the light pattern formed by the direct light and more reflected light is directed toward the ends of the light pattern than toward the middle thereof;

said filament being positioned between said focal point and said aperture such that the amount of reflected light directed toward the ends of the light pattern will be increased whereby the rectangular light pattern made up of combined direct light and reflected light will be generally uniform and of an area which is relatively large with respect to said aperture.

2. The device of claim 1 wherein means are provided to maintain said lamp housing in close proximity to the area to be illuminated.

3. The device of claim 2 wherein a transformer is included to regulate the power from the power source connected to said light source.

4. The device of claim 3 wherein said means to maintain said lamp housing in close proximity to the illuminated area are adjustable and said means comprises a flexible arm connecting said lamp housing and said transformer.

5. The device of claim 1 wherein said lamp housing includes upper and lower walls to enclose the ends of said elliptic channel; and said filament is positioned on the major axis of the elliptic reflector equidistant between said upper and lower walls.

6. The device of claim 5 wherein the filament of said lamp is substantially perpendicular to said upper and lower walls.

7. The device of claim 1 wherein the means are provided to mount the light unit.

8. The device of claim 1 wherein the tip of said bulb is treated to reduce the direct light emanating therefrom.