GB2294909A

GB2294909A - Acid etched gobo

Info

Publication number: GB2294909A
Application number: GB9520927A
Authority: GB
Inventors: Byron J Ziegler; Steven T Mahanay
Original assignee: High End Systems Inc
Current assignee: High End Systems Inc
Priority date: 1994-11-14
Filing date: 1995-10-12
Publication date: 1996-05-15
Anticipated expiration: 2015-10-12
Also published as: GB2294909B; GB9520927D0; DE19540840A1

Description

ACID ETCHED GOBO 2294909 This invention relates generally to stage and

entertainment lighting and more particularly to projecting light produced images by passing a beam of light through a multi-coloured, single substrate light pattern generator or gobo used in a light fixture for producing coloured light patterns.

Presently, single substrate, multi-coloured gobos are produced by laser etching of a ceramic coated glass substrate. The laser etching establishes the pattern in the ceramic coating, after which coloured gels are baked into the pattern to produce the desired results.

Limitations to this process include high cost, very low resolution of the patterns, incapable of producing photo quality patterns and a limit on the size of the gobos which can be produced.

Another process paints coloured patterns on a glass substrate. However, these painted gobos are very limited in their heat tolerance when the gobo is placed in a lighting projection system.

In one aspect of the present invention, this is accomplished by providing an acid etched gobo for producing a multi-coloured light pattern comprising a substrate which includes a dichroic coating. A multicoloured light pattern is formed in the dichroic coating in response to a random patterned partial acid etching to various depths of the coating.

In a further aspect of the present invention, this is accomplished by providing an acid etched gobo for producing a multi-coloured light pattern comprising a substrate which includes a dichroic coating. A multi-coloured light pattern is f ormed in the dichroic coating in response to the substrate being spun as a photoresist substance is applied to the coating so that the photoresist splays outwardly over portions of the coating due to centrifugal f orce, to ef f ect a random patterned partial photoresist mask, whereby subsequent acid etching of the substrate etches to various depths of other portions of the dichroic coating which are free of the photoresist mask.

For a better understanding of the invention and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawings, in which:- Fig. 1 is a perspective view illustrating a gobo; Fig. la is an exaggerated cross-sectional view taken along the line la-la of Fig. 1; Fig. 2 is a schematic view illustrating the gobo being spun during application of an etching substance; Fig. 3 is a schematic view illustrating a gobo being spun during application of a masking substance; and Fig. 4 is a schematic view illustrating the gobo movably mounted in a projected light path.

An acid etched gobo 10, Fig. 1, comprises a disc-shaped substrate 12, preferably of borosilicate glass, and includes a dichroic coating 14 which is comprised of alternating films of the metal oxides, silicon dioxide and titanium dioxide. The colour ef f ects of dichroic f ilms are dependent on the thickness and total number of the alternating layers.

A multi-coloured light pattern is f ormed in the dichroic coating in response to a random pattern 15 ' partial acid etching to various depths of coating 14. The random pattern 15 may be accomplished by permitting an acid etch solution, f or example, a 2 - 3% solution of hydrofluoric acid in water, to be randomly permitted to drip onto the dichroic coating 14, or may be sprayed on. The gobo 10 of Fig. 1 includes, for example, a yellow random shape in the area designated y and a red random shape in the area designated r, see Fig. la.

Instead, see Fig. 2, the acid etch may be permitted to drip onto the dichroic coating 14 as the gobo 10 is spun about its centroidal axis A, in a direction indicated by arrow S, so that the dripping acid splays outwardly over portions of the coating 14 due to centrifugal force to effect a random patterned partial acid etching 15a to various depths of the coating. The acid is permitted to etch into the dichroic coating 14 f or a period of from under one minute up to about ten minutes depending on the multi-colour effect desired.

As another possibility, see Fig. 3, a commercially available photoresist substance 16, e.g. Microposit S1805 sold by Shipley, Inc. of Marlborough, MA, U.S.A., may be permitted to drip onto the dichroic coating 14 as the gobo 10 is spun about its centre axis so that the dripping photoresist 16 splays outwardly over portions of the coating 14 due to centrifugal force, to effect a random patterned partial photoresist mask 16, whereby subsequent acid etching etches to various depths of other portions of the dichroic coating 14 which are free of the photoresist mask 16.

Various random pattern effects can be accomplished as described above or by other means. A mask such as the photoresist 16, or waxes, oils, crystals both hydrophobic and hydrophilic, and other hydrophobic materials, can be introduced onto the dichroic coating 14. The mask 16 can be manipulated on the coating 14 in such a way so as to leave parts of the coating 14 unmasked. The patterns left by the mask 16 will be chaotic, random and unique. The gobo 10 can then be introduced into an etching solution that will etch off the portions of the coating 14 that are not masked. The etching process can be limited, with respect to time, to achieve the desired multi-coloured result as stated above. The result, according to this process, can produce a multi-coloured tie-die effect similar to cloth being folded or tied and then dipped into colour dyes.

There are several ways to manipulate the selected masking onto the dichroic coating 14. As previously discussed, the gobo 10 can be spun in some suitable manner, such as by mounting and securing the gobo 10 on a spinning disc 18 mounted on a rotating shaft 20, while applying the mask 16. Other substances can be applied with the mask substance to manipulate the mask before it dries. Such other substances include, for example, alcohol, acetone and water.

Following masking, the etching solution could also be manipulated onto the dichroic coating. The semi-masked coatings can be completely or partially submerged in the etching solution. The etching solution can also be sprayed or dripped onto the semi-masked coating.

As is well known in entertainment lighting, the gobo 10, Fig. 4, may be movably mounted in a gobo, wheel 36, which bi-directionally rotates as indicated by the arrow R, so that when the gobo 10 is moved into the path of a light beam B, generated from a light source 11, the selected gobo image 38 is in position to be projected by the light onto a projection surface 40. Present gobos also bidirectionally rotate as indicated by the arrow M, independent of the wheel 36, once the gobo is positioned in the beam B. Also, a colour wheel 22, which includes a plurality of various colour discs 24, can be bidirectionally rotated as indicated by the arrow Rf to vary colour and enhance the light of beam B and the selected gobo image 38 projected on to the projection surface 40 which may be a solid surface or theatrical fog.

Claims

CLAIMS:

1. An acid etched gobo f or producing a multi-coloured light pattern comprising a substrate, a dichroic coating deposited on the substrate, and a multi-coloured random light pattern formed in the dichroic coating in response to acid etching being randomly applied to portions of the coating.

2. An acid etched gobo f or producing a multi-coloured light pattern comprising a substrate, a dichroic coating deposited on the substrate, and a multi-coloured light pattern formed in the dichroic coating in response to the substrate being spun as an acid etch is applied to the coating so that the acid splays outwardly over portions of the coating due to centrifugal force, to effect a random patterned partial etching to various depths of the coating.

3. An acid etched gobo f or producing a multi-coloured light pattern comprising a substrate, a dichroic coating deposited on the substrate; and a multi-coloured light pattern formed in the dichroic coating in response to the substrate being spun as a photoresist substance is applied to the coating so that the photoresist splays outwardly over portions of the coating due to centrifugal force, to effect a random patterned partial photoresist mask, whereby subsequent acid etching etches to various depths of other portions of the dichroic coating which are free of the photoresist mask.

4. An acid etched gobo, substantially as described herein with reference to Figures 1 and la and 4, with or without the modification of Figure 2 or 3 of the accompanying drawings.