# US 4,394,717 A · Illumination system for copying apparatus

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- Number: US 4,394,717 A
- Document ID: US4394717A
- Status: Granted
- Kind: A
- Application number: 06/342,616
- Filed: 1982-01-25
- Granted: 1983-07-19
- Earliest claimed: 1981-02-02
- Assignees: Ciba-Geigy Corporation
- Inventors: Malcolm G. Brockwell
- Web page: https://patentgrep.com/patent/US4394717A

## CPC

- F21V 7/05: plane
- G03B 27/547: {colour mixing heads}
- F21V: FUNCTIONAL FEATURES OR DETAILS OF LIGHTING DEVICES OR SYSTEMS THEREOF; STRUCTURAL COMBINATIONS OF LIGHTING DEVICES WITH OTHER ARTICLES, NOT OTHERWISE PROVIDED FOR
- G03B: APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR (optical parts of such apparatus G02B; photosensitive materials or processes for photographic purposes G03C; apparatus for processing exposed photographic materials G03D)

## Abstract

The system comprises two light sources which are diametrically opposed relative to the optical axis of the system. In the axis there is provided a light-mixing mirror which has a generally sulcated face having grooves therein of triangular cross-section and raised portions of triangular cross-section separating the grooves. Light coming from the two light sources slightly diverges when it impinges the sulcated face of the mirror and is deflected into the direction of the optical axis thereby being intensively mixed.

## Claims

### Claim 1

An illumination system for a photographic copying apparatus for mixing light from two sources (1a, 1b), which illumination system comprises disposed along a longitudinal optical axis (5) a light-mixing mirror (16) which has as the light-mixing face (16a) a generally sulcated face having grooves (17) therein of triangular cross-section and raised portions of triangular cross-section separating the grooves such that alternate facets (17a, 17b) are parallel, said two light sources (1a, 1b) being diametrically opposed relative to the longitudinal axis (5) and located below the sulcated face (16a) and each being adapted to direct light onto said light-mixing mirror (1b) from an angle (.beta.) relative to said longitudinal axis (5) which is twice the complement of the angle (.alpha.) made by one of the sets of said parallel facets (17a, 17b) relative to the longitudinal axis (5), the general plane of the sulcated face (16a) of the light-mixing mirror (16) being disposed normal to the said longitudinal axis and the grooves (17) therein having smooth polished reflecting surfaces (17a, 17 b) and extending normal to a plane containing both light sources and the longitudinal axis (5), light from the two light sources striking the light-mixing mirror (16) and being reflected therefrom substantially along the longitudinal axis.

### Claim 2 (depends on 1)

An illumination system according to claim 1 wherein the apex angle (.gamma.) of each of the raised portions of triangular cross-section is 120.degree. and the light from the two light sources is directed onto the light-mixing mirror at 60.degree. relative to the longitudinal axis.

### Claim 3 (depends on 1, 2)

An illumination system according to claim 1 or claim 2, wherein the optical systems employed to direct light from the light sources to the light-mixing mirror are such that beams of light from each source when they reach the sulcated face are slightly diverging.

### Claim 4 (depends on 1)

An illumination system according to claim 1, wherein a colour-selective filter is present in the path of the light from at least one of the two sources.

### Claim 5 (depends on 1)

An illumination system according to claims 1, wherein one of the two light sources comprises two lamps and a beam combiner is present, the two lamps being so arranged that a single beam of light from the beam combiner is directed on to the sulcated face of the light-mixing mirror at an angle of substantially 60.degree. relative to the longitudinal axis of the system.

### Claim 6 (depends on 5)

An illumination system according to claim 5 wherein the beam combiner is colour selective.

### Claim 7 (depends on 1)

An illumination system according to claim 1, wherein the reflecting surface of the facets of the sulcated mirror consists of a dichroic coating which reflects the actinic components of the light but transmits infra-red radiation.