GB2123941A - Lighting instrument - Google Patents

Abstract

A lighting instrument, particularly for use in lighting stages, studios, and places where public entertainments take place, includes: a source of polychromatic light; at least one reflective colour separation filter arranged to reflect light having a chosen spectral range along a different path from the transmitted beam; means for separately controlling the intensity of these beams; and means for recombining the separated beams. There may be at least two different reflective colour separation filters (1, 4, 5, 8) arranged so that the separated, i.e. reflected, light beam follows a different path from the remaining, i.e. transmitted, beam, a variable aperture (V1, V2, V3) in the path of each of two out of the three beams so formed, namely two separated beams and the remaining beam, means for recombining the separated beams with the remaining beam (e.g. mirrors 2, 3, 6, 7), and means for separately varying the sizes of the two apertures (Figure 1). <IMAGE>

Description

SPECIFICATION Lighting instrument This invention relates to a lighting instrument, particularly although not exclusively for use in lighting stages, studios, and places where public entertainments take place.

It has been conventional where a coloured light is required to use a light source which emits polychromatic (white) light and place in front of it a colour filter. Different filters are used to obtain different colour effects and it has been necessary to remove one filter and replace it by another when a different colour effect is required. To the best of the Applicants' knowledge and belief, it has not been hitherto practical to make continuous changes in colour effects, that is to say, changes without interuption, nor has it been practical to obtain output light of any desired spectral range and to change without interuption from one spectral range to another.

According to the invention, there is provided a lighting instrument which includes a source of polychromatic light, at least one reflective colour separation filter arranged to reflect light having a chosen spectral range along a different path from the transmitted beam, means for separately controlling the intensity of these beams, and means for recombining the separated beams.

According to an advantageous embodiment of the invention, a lighting instrument includes a source of polychromatic light, at least two different reflective colour separation filters arranged so that the separated, i.e. reflected, light beam follows a different path from the remaining, i.e. transmitted, beam, a variable aperture in the path of each of two out of the three beams so formed, namely two separated beams and the remaining beam, means for recombining the separated beams with the remaining beam, and means for separately varying the sizes of the two apertures.

In a preferred embodiment of the invention a lighting instrument includes a source of polychromatic light, a first 450 reflective colour separation filter disposed in the path of the light to produce a beam of a first colour (e.g. red) which follows a path different from the beam transmitted by the first filter, a second 45" reflective colour separation filter located in the transmitted beam issuing from the first filter and arranged to produce a beam of light of a second colour (e.g. blue) different from the first colour, (the beam transmitted by the second filter in this instance being green), three variable apertures of which one is disposed in the path of the first colour beam, one is disposed in the path of the second colour beam, and the third is disposed in the path of the beam of light transmitted from the second filter, the instrument also including means for combining the first colour beam, the second colour beam, and the transmitted beam from the second filter, and means for separately varying the sizes of the respective apertures.

In one embodiment of the invention, the combining means include a pair of 45" plain flat reflectors (e.g. mirrors) for each of the first and second colour beams. The source of light for example may be a 100 watt or 150 watt halogen lamp, or may be an arc lamp such as is used for stage lighting. A suitable casing for the lighting instrument includes means for mounting the filters and the reflectors, and may include leadscrew or lever adjustment devices for adjusting the sizes of the variable apertures; alternatively the aperture sizes may be adjusted by individual small electric motors which can respond to electrically-generated or microcomputer generated command signals.

The invention will be better understood from the following description of two examples thereof, given with reference to the accompanying schematic drawings in which Figure 1 illustrates one possible optical arrangement for a lighting instrument according to the invention, and Figure2 illustrates an alternative optical arrangement.

Referring firstly to Figure 1, this illustrates one example of the invention and shows a polychromatic light source from which emanates white light diagramatically represented as a combination of red, green and blue beams. Red is represented buy a dashed line made up of short dashes, green is represented by a continuous line and blue is represented by a dashed line made up of long dashes. The polychromatic beam impinges on a 45" red reflective colour separation filter 1, which produces a reflected red beam and a transmitted beam consisting of the green and blue components. One example of a suitable filter is that known as a 45" colour separation filter produced by Optical Coating Laboratory Inc., 2789 North point Parkway, Santa Rosa, CA 95402, U.S.A.The reflected red beam then impinges on a plain mirror 2, passes through a variable aperture V3, and then impinges upon a plain mirror 3. The mirrors 2 & 3 are arranged at 45" to the direction of the incident beam in each case, and the reflected beam from mirror 3 falls upon a second 45" red reflective colour separation filter 4, also arranged at 45" as shown to the incident beam.

The blue component of the polychromatic beam passes through the filter 1, and impinges upon a 45" blue reflective colour separation filter 5 which produces a reflected beam of blue light and a transmitted beam of green light. The reflected blue beam impinges then upon two plain mirrors 6 & 7 and then upon a second 45" blue reflective colour separation filter 8. The blue beam passes through a variable aperture V1 between the mirrors 6 & 7.

The transmitted beam from the filter 5 passes through a a variable aperture V2 and then through the 45" red reflective colour separation filter 4 and then through the 45" blue reflective colour separation filter 8. As a result the beam emanating from the filter 8 is a combination of the red, blue and green components, and it will be readily seen that by varying one or more of the variable apertures V1, V2 (which operates upon the green component) and V3 the colour of the output light beam can be varied as desired.

Referring now to Figure 2, this illustrates an alternative optical arrangement and like parts are denoted by like reference numerals. Compared to the Figure 1 arrangement, the Figure 2 arrangement requires only two plain mirrors, 2 & 3, and is a more compact layout. It will be appreciated that yet further alternative arrangements are possible without departing from the concept of the present invention.

It is envisaged that the present invention will be useful in public entertainments, stage shows, and moreover the invention could be emboded in a domestic light source or lamp which would allow a householder to achieve novel and interesting colour effects.

CLAIMS (Filed on 2 Aug 1982) 1. A lighting instrument which includes a source of polychromatic light, at least one reflective colour separation filter arranged to reflect light having a chosen spectral range along a different path from the transmitted beam, means for separately controlling the intensity of these beams, and means for recombining the separated beams.

2. A lighting instrument which includes a source of polychromatic light, at least two different reflective colour separation filters arranged so that the separated, i.e. reflected, light beam follows a different path from the remaining, i.e. transmitted, beam, a variable aperture in the path of each of two out of the three beams so formed, namely two separated beams and the remaining beam, means for recombining the separated beams with the remaining beam, and means for separately varying the sizes of the two apertures.

3. A lighting instrument which includes a source of polychromic light, a first 45" reflective colour separation filter disposed in the path of the light to produce a beam of a first colour (e.g. red) which follows a path different from the beam transmitted by the first filter, a second 45" reflective colour separation filter located in the transmitted beam issuing from the first filter and arranged to produce a beam of light of a second colour different from the first colour, three variable apertures of which one is disposed in the path of the first colour beam, one is disposed in the path of the second colour beam, and the third is disposed in the path of the beam of light transmitted from the second filter, the instrument also including means for combining the first colour beam, the second colour beam, and the transmitted beam from the second filter, and means for sepa ratelyvarying the sizes of the respective apertures.

4. A lighting instrument according to claim 3 in which the combining means include a pair of 45" plain flat reflectors (e.g. mirrors) for each of the first and second colour beams.

5. A lighting instrument according to claim 1,2,3 or 4 which includes means for mounting the filters and the reflectors, and which includes leadscrew or lever adjustment devices for adjusting the sizes of the variable apertures.

6. A lighting instrument according to claim 1,2,3 or 4 in which the aperture sizes are adjustable by individual small electric motors which can respond to electrically-generated or micro-computer generated command signals.

7. A lighting instrument substantially as herein described with reference to and as illustrated in Figure 1 or Figure 2 of the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (7)

**WARNING** start of CLMS field may overlap end of DESC **. the Figure 1 arrangement, the Figure 2 arrangement requires only two plain mirrors, 2 & 3, and is a more compact layout. It will be appreciated that yet further alternative arrangements are possible without departing from the concept of the present invention. It is envisaged that the present invention will be useful in public entertainments, stage shows, and moreover the invention could be emboded in a domestic light source or lamp which would allow a householder to achieve novel and interesting colour effects. CLAIMS (Filed on 2 Aug 1982)

1. A lighting instrument which includes a source of polychromatic light, at least one reflective colour separation filter arranged to reflect light having a chosen spectral range along a different path from the transmitted beam, means for separately controlling the intensity of these beams, and means for recombining the separated beams.

2. A lighting instrument which includes a source of polychromatic light, at least two different reflective colour separation filters arranged so that the separated, i.e. reflected, light beam follows a different path from the remaining, i.e. transmitted, beam, a variable aperture in the path of each of two out of the three beams so formed, namely two separated beams and the remaining beam, means for recombining the separated beams with the remaining beam, and means for separately varying the sizes of the two apertures.

3. A lighting instrument which includes a source of polychromic light, a first 45" reflective colour separation filter disposed in the path of the light to produce a beam of a first colour (e.g. red) which follows a path different from the beam transmitted by the first filter, a second 45" reflective colour separation filter located in the transmitted beam issuing from the first filter and arranged to produce a beam of light of a second colour different from the first colour, three variable apertures of which one is disposed in the path of the first colour beam, one is disposed in the path of the second colour beam, and the third is disposed in the path of the beam of light transmitted from the second filter, the instrument also including means for combining the first colour beam, the second colour beam, and the transmitted beam from the second filter, and means for sepa ratelyvarying the sizes of the respective apertures.

4. A lighting instrument according to claim 3 in which the combining means include a pair of 45" plain flat reflectors (e.g. mirrors) for each of the first and second colour beams.

5. A lighting instrument according to claim 1,2,3 or 4 which includes means for mounting the filters and the reflectors, and which includes leadscrew or lever adjustment devices for adjusting the sizes of the variable apertures.

6. A lighting instrument according to claim 1,2,3 or 4 in which the aperture sizes are adjustable by individual small electric motors which can respond to electrically-generated or micro-computer generated command signals.

7. A lighting instrument substantially as herein described with reference to and as illustrated in Figure 1 or Figure 2 of the accompanying drawings.