Claims
- 1. A lamp structure which comprises:
- (i) a concave reflector having an axis
- (ii) a plurality of light sources, wherein the number of light sources is N, said light sources being spaced apart within said reflector and arranged about said axis on a notional annulus
- (iii) a body disposed within the reflector substantially concentrically about said axis said body having a plurality of reflective segments on its surface outwardly from said axis, the number of reflective segments being N or a multiple of N, each segment viewed in cross-section having at least two curved surfaces that meet together in a peak, each light source being located opposite to the peak of a respective segment, and wherein intermediate between each pair of adjacent light sources, the body includes a further peak that extends into the notional annulus on which the light sources are arranged to shield the adjacent light sources from each other.
- 2. The lamp structure of claim 1, wherein the said body has D.sub.N or C.sub.N symmetry.
- 3. The lamp structure of claim 1, wherein each curved surface of each segment, in cross-section, has a geometric shape corresponding to a section of a circle, of a sinusoidal wave or of the involute of a parabola or of a curve of higher power.
- 4. The lamp structure of claim 3, wherein the said geometric shapes have been stretched, contracted, stretched and contracted, rotated, stretched and rotated, contracted and rotated or stretched and contracted and rotated.
- 5. The lamp structure of claim 1, wherein the reflecting surfaces of the central mirrored body are partially diffusing.
- 6. The lamp structure of claim 1, wherein each of the said further peaks extends into the said annulus but does not extend completely through the said annulus.
- 7. The lamp structure of claim 1, wherein the concave surface of the reflector has the shape of a body of rotation.
- 8. The lamp structure of claim 7, wherein the reflector has the shape of a higher order than a paraboloid.
- 9. The lamp structure of claim 8, wherein the reflector has an annular focal area and the said light sources are arranged in the vicinity of that area.
- 10. The lamp structure of claim 1, wherein separate light sources are connected to separate phases of a phase-shifted alternating current supply.
Priority Claims (1)
| Number |
Date |
Country |
Kind |
| 4254/86 |
Oct 1986 |
HUX |
|
Parent Case Info
This application is a continuation in part of application No. 107,952, filed on Oct. 13, 1987, now abandoned.
The present invention relates to a lighting apparatus and in particular to a lighting apparatus that produces an intense light beam.
The light output of a lighting apparatus is generally limited by the thermal load on the light sources as a result of the heat generated by the light sources themselves; as the output of a light source is increased, so its service life decreases, due principally to the extraordinary high thermal load placed upon it. Our invention provides a lighting apparatus in which, for a given output of the apparatus, the life of the light sources is increased.
In lighting of film and television sets, it is desirable to provide a lighting apparatus that produces a single, defined shadow since lighting apparatuses that produce several shadows give an unrealistic effect. Single shadows can be generated by a single light source or bulb but the intensity of a light beam produced by a single light source is limited by the thermal load on the light source at the high temperatures necessary to produce intense light. In one embodiment, the present invention provides a lighting apparatus that emulates a single light source in that it gives a single shadow while being composed of several light sources and, as a result of using several light sources, can produce an intense light beam. Also, by the arrangement of the present invention, the light is provided at high efficiency.
DE-B-No. 1,227,404 describes a lighting apparatus comprising a parabolic mirror in which six plasma lamps are arranged annularly around a central axis. In order to improve the uniformity of a lighting apparatus, a mirror is placed within the annulus formed by the lamps; the mirror is so shaped that it reflects light from the lamps to form a virtual image of the lamps in the spaces between adjacent lamps. Thus the lighting apparatus appears to have twelve lamps (six real lamps and six virtual images) thereby providing a more homogeneous light beam than an apparatus including only six bulbs. However, such an apparatus places a high thermal load on the light sources and also produces multiple
According to the present invention, there is provided a lamp structure which comprises:
(i) a concave reflector having an axis
(ii) a plurality of light sources, wherein the number of light sources is N, said light sources being spaced apart within said reflector and arranged about said axis on a notional annulus
(iii) a body disposed within the reflector substantially concentrically about said axis said body having a plurality of reflective segments on its surface outwardly from said axis, the number of reflective segments being N or a multiple of N, each segment viewed in cross-section having at least two curved surfaces that meet together in a peak, each light source being located opposite to the peak of a respective segment, and wherein intermediate between each pair of adjacent light sources, the body includes a further peak that extends into the notional annulus on which the light sources are arranged to shield the adjacent light sources from each other.
The said further peaks may extend partially into the said notional annulus or may pass right through the whole thickness of the annulus.
It is preferred that the central reflective body has D.sub.N or C.sub.N symmetry; an article having D.sub.N symmetry has N planes of mirror symmetry and can be rotated around an axis by 360/N degrees to provide an article of identical appearance whereas an article having C.sub.N symmetry can be rotated around an axis by 360/N degrees to provide an article of identical appearance but the article has no planes of mirror symmetry.
The body can be of constant cross-section (thereby forming a column), or it may taper (thereby forming a cone or a pyramid).
We have found that a single shadow can be obtained from a lighting apparatus containing several light sources if the reflector is a rotary-symmetric mirror the reflecting surface of which has a high order shape providing an annular focal region and if the light-emitting parts of the light sources are arranged in the vicinity of the focal region and preferably on a notional surface of the focal region. A shape of `higher order` is a shape that can be defined by the equation
US Referenced Citations (4)
Foreign Referenced Citations (3)
| Number |
Date |
Country |
| 1227404 |
Oct 1966 |
DEX |
| 859696 |
Dec 1940 |
CHX |
| 282255 |
Dec 1927 |
GBX |
Continuation in Parts (1)
|
Number |
Date |
Country |
| Parent |
107952 |
Oct 1987 |
|
Patent Grant
4965876
