GB2044480A

GB2044480A - Exposing photosensitive materials

Info

Publication number: GB2044480A
Application number: GB8004485A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1979-02-19
Filing date: 1980-02-11
Publication date: 1980-10-15
Also published as: GB2044480B; IT8019994A0; ES241467Y; ES241467U; IT1141226B; FR2449295A1

Abstract

A photosensitive surface layer of an article 3 is exposed to sensitizing radiation through a transparency 2 located between the article and a hollow body 1 in which the article is fixedly located. The hollow body is transparent to the radiation and the radiation-emitting source is located externally of the body. Relative rotational movement between the body and its contents and the radiation-emitting source provides uniform irradiation of the transparency. The body is preferably in more than one part to ease assembling and dismantling around the article. <IMAGE>

Description

SPECIFICATION Photographic engraving The present invention relates to photographic engraving and provides a method of exposing a photosensitive layer on a article to be engraved and apparatus for use in said method.

In photographic engraving, an article to be engraved is coated or otherwise treated to provide a photosensitive layer which is exposed to sensitizing radiation through a transparency bearing the pattern to be engraved. It is necessary in known photographic engraving processes to maintain overall contact between the article to be engraved and the transparency during exposure of the photosensitive layer. Whilst this requirement causes no difficulty in the case of flat articles, where for example, vacuum isolation presses can be used, it does present'serious problems when dealing with conical or cylindrical articles because the sensitizing radiation does not uniformly irradiate the transparency. It is an object of this invention to overcome said problem of non-uniform irradiation.

According to a first aspect of the present invention, there is provided a method of photographic engraving wherein an article having a photosensitive surface layer is fixedly located within a hollow body transparent to sensitizing radiation to be-used to expose said surface layer and with a transparency bearing the pattern to be engraved located between the body and the article; and wherein the said surface layer is exposed through said body and transparency to the sensitizing radiation whilst relative, rotational movement between the body and the radiation-emitting source causes the transparency to be uniformly irradiated during the exposure time.

According to a second aspect of the present invention, there is provided apparatus for use in the method of the invention which comprises a hollow body transparent to sensitizing radiation for. exposing a photosensitive layer; article-locating means for fixedly locating within the body an article having a photosensitive surface layer; and a transparency located within the body and bearing a pattern to be engraved on said article, the arrangement being such that an article located by said article-locating means can be exposed to sensitizing radiation through the body and the transparency whilst relative rotational movement of the body and a radiation emitting source permits of the transparency being uniformly irradiated during one traverse of the radiation over the body.

Preferably, the hollow body is rotary whereby the body and its contents can be rotated for uniform irradiation from a spatially fixed radiation-emitting source. Suitably, the hollow body is composed of a plurality of removable sections to facilitate insertion and removal of the article to be engraved.

The invention also provides in combination, apparatus of the invention; a radiation emitting source; and means for causing relative rotational movement between the body of the apparatus and the source to uniformly irradiate the transparency within said body.

The following is a description, by way of example only and with reference to the ac companying drawings, of an embodiment of the present invention. In the drawings:~ Figure 1 is a diagrammatic plan view of apparatus in accordance with said embodiment of the invention; and Figure 2 is a diagrammatic cross-section of the apparatus of Fig. 1 on the line A-B of Fig.

1.

Referring to the drawings, apparatus in accordance with an embodiment of the invention comprises a hollow cylindrical drum 1 which is divided into several different parts to allow it to be taken apart to facilitate insertion and removal of an article 3 into and from the interior thereof. The drum is made of a material which is transparent to a relevant radiation and houses within itself a film or other transparency 2. The transparency adapts completely to the drum and is located between the drum 1 and the article 3 to be exposed to radiation. The apparatus thus composed is subjected to a rotary movement so that radiation emitted by a radiation emitting source passes through the drum 1 and irradiates the article 3 through the transparency 2 with uniform intensity. The rotary movement of the apparatus causes the radiation to reach all points of the transparency with identical intensity during each traverse of the radiation over the drum.

It will be appreciated that the invention is not restricted to the particular details described above with reference to the drawings and that numerous modifications and variations can be made without departing from the scope of the invention as defined in the following claims. In particular, the drum 1 can be replaced by a body which generally adapts to the shape of a particular non-cylindrical article when such an article is to be engraved.

Claims

1. A method of photographic engraving wherein an article having a photosensitive surface layer is fixedly located within a hollow body transparent to sensitizing radiation to be used to expose said surface layer and with a transparency bearing the pattern to be engraved located between the body and the articles; and wherein the said surface layer is exposed through said body and transparency to the sensitizing radiation whilst relative rotational movement between the body and the radiation-emitting source causes the transparency to be uniformly irradiated during the exposure time.

2 A method as claimed in Claim 1 wherein the hollow body rotates whilst the radiation-emitting source is spatially fixed.

3. A method of photographic engraving substantially as hereinbefore described with reference to the accompanying drawings.

4. An article whenever engraved by a method as claimed in any one of the preceding claims.

5. Apparatus for use in a method as claimed in Claim 1 which comprises a hollow body transparent to sensitizing radiation for exposing a photosensitive layer; article-locating means for fixedly locating within the body an article having a photosensitive surface layer; and a transparency located within said body and bearing a pattern to be engraved on said article, the arrangement being such that an article located by said article-locating means can be exposed to sensitizing radiation through the body and the transparency whilst relative rotational movement of the body and a radiation-emitting source permits of the transparency being uniformly irradiated during one traverse of the radiation over the body.

6. Apparatus as claimed in Claim 5 wherein the hollow body is a rotary body.

7. Apparatus as claimed in Claim 6 wherein the hollow body comprises a plurality of removable sections to facilitate insertion and removable of the article to be engraved.

8. Apparatus as claimed in any one of Claims 5 to 7 wherein the hollow body is a cylindrical drum.

9. Apparatus as claimed in any one of Claims 5 to 8 wherein the transparency follows the contour of the inner surface of the hollow body.

10. Apparatus as claimed in Claim 5 and substantially as hereinbefore described with reference to and as diagrammatically shown in the accompanying drawings.

11. In combination, apparatus as claimed in any one of Claims 5 to 10; a radiationemitting source; and means for causing relative rotational movement between the body of the apparatus and the source to uniformly irradiate the transparency within said body.

12. Device for the exposure of non-flat objects, in photographic engraving processes, to radiations, said device being essentially characterized by the fact that it is composed of a drum made of material transparent to the radiations of any pertinent type of emitting source, being adapted in shape to the type of pieces or objects to be irradiated, thereby constituting a retaining element for the pieces housed within it, with a film or transparency inserted between drum and piece to be en graved.

13. Device for the exposure of non-flat objects, in photographic engraving processes, to radiations, according to Claim 12 above, characterized by the fact that said drum is divided into several parts, allowing it to be taken apart when so desired to ease insertion and removal of pieces within it.

14. Device for the exposure of non-flat objects in photographic engraving processes, to radiations, according to either of Claims 12 and 13 characterized by the fact that it is equipped with appropriate means allowing it to revolve during the time in which the pieces are exposed to radiation.