GB2134663A

GB2134663A - A method of exposing printing plates or film

Info

Publication number: GB2134663A
Application number: GB08401690A
Authority: GB
Inventors: Yutaka Mori
Original assignee: Individual
Current assignee: Individual
Priority date: 1983-02-01
Filing date: 1984-01-23
Publication date: 1984-08-15
Also published as: GB8401690D0; DE3403473A1; GB2134663B; JPS59140451A

Abstract

A method of exposing printing plates or film in brightly-lit rooms employs an enclosure (1), inside which is a light source (2). The light is converged by passing through first and second condenser lenses (3) and (4), and then passes through filter (5), the subject transparency (6), a lens (8) with a shutter (7), and onto a plate or film. The plate or film is thereby exposed to a powerful and uniform light which, due to the filtering comprises the wavelengths to which the plate or film is sensitive. <IMAGE>

Description

SPECIFICATION A method of making printing plates or film This invention relates to a method of making plates or film for use in a printing process. The plates or film have a light-sensitive coating and are usable in a brightly-lit room in association with a light source and a lens.

In the past with an ordinary apparatus for making printing plates, a plano-light source was used as the illuminating light source, such as a halogen lamp or fluorescent lamp. The light passed through the subject material and was incident on a lens, but because only an extremely small portion of the light was incident on the lens, and because of insufficient light, or light not complying with the required wave-length, proper exposure was not possible. Even if the light passed through the lens, the image would not come out at all or it took a time and the resulting image was blurred and of poor quality and was completely unusable for exposing the plate. For that reason a close contact method has been employed for selectively hardening the lightsensitive coating by directly exposing the entire subject to light from a light source which has not been passed through a iens.Therefore at present a negative or positive has to be retaken by means of a camera, to agree with the pre-determined quality needed for close contact work.

A main object of this invention is to expose directly any kind of printing plate, or film usable in brightly-lit rooms, using an apparatus which eliminates the need to make a negative or positive film of the same proportional size and then to place that film in close contact in order to make a printing plate or film of the same size.

According to the invention there is provided a direct method of making printing plates or film usable in brightly-lit rooms, in which a light source is disposed on the optical axis inside an enclosure, the light from the light source is condensed and intensified by a lens system and is passed through an appropriate filter, then through a subject transparency and then passes through a lens with a shutter onto a printing plate or a film which is held stationary, said plate or film being thereby exposed by a powerful uniform light which conforms to the wave-length response of the photosensitive material.

An embodiment of the invention will now be described, by way of example, with reference to the accompanying drawing which is a diagrammatic view of the operation of the method of the invention.

The figure shows an apparatus for making a printing plate in which there is a high density mercury light source 2 disposed on the optical axis of the body of an enclosure 1. The light from the light source 2 is rendered convergent by a first lens 3 which is in an adjustable unrestricted position, and is then further condensed and intensified by a second, large aperture lens 4 such as a condenser lens or a Fresnel lens.

Alternatively, a single condenser lens can be used to reduce the distance from the light source to the lens. The light which has passed through the lens or lenses then passages through an appropriate filter, through the subject material 6, then through lens 8 with a shutter 7, and is incident on one of a variety of printing plates or film 10 usable in brightly-lit rooms or the like, which is held stationary by suction or the like to a board 9. A powerful uniform light source complying accurately to the appropriate wave-lengths of the photosensitive material is thus provided.

In the past in close contact hardening of the sensitive layer with incident light, the source of light was made as small as possible, e.g. a point source. Moreover a strong light was desirable.

In cases of when photographing or when evenly dispersing the light for use as an incident light, the ideal way is to further converge and condense the light source by passing it through a photographic lens. For such a purpose, the ideal source of light wouid be a high density mercury source which is strong in ultraviolet radiation, a metal halide source or a xenon lamp. A watercooled mercury source is particularly effective.

Furthermore when there are a lot of intermediate steps, errors are cumulative, and the product is bad. Therefore simplification of this process is a required condition for producing a good product.

In this invention, the method employs an apparatus which can be readily set up. Thus errors from intermediate steps do not occur and a printing plate or film can be made immediately with this direction method.

With this apparatus there is less absorption of light and so a uniform light suitable for film usable in brightly-lit rooms, or one of a variety of printing plates, is passed through the appropriate filter 5, the subejct transparency 6, through the lens 8 with the shutter 7, on to one of a variety of printing plates 10, for example an offset printing plate, a letterpress (relief) resin printing plate, a screen printing plate, or film usable in brightly-lit rooms or the like, which light sensitive material is held stationary by suction or the like to the board 9.

The light from the light source which has been rendered convergent and dispersed through lenses 3 and 4 using filter 5 and passes through the subject material 6. The uniform illumination of the subject material is then condensed by lens 8 accurately and sufficiently to expose the plate in conformity to the wave-length response of the photosensitive material. Thus it is possible to make a printing plate or film directly by heatsetting using a lens without requiring the making of a film for close contact, thereby reducing cost for material, iabour and the loss of time.

Claims

1. A direct method of making printing plates or film usable in brightly-lit rooms, in which a light source is disposed on the optical axis inside an enclosure, the light from the light source is condensed and intensified by a lens system and is

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

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION A method of making printing plates or film This invention relates to a method of making plates or film for use in a printing process. The plates or film have a light-sensitive coating and are usable in a brightly-lit room in association with a light source and a lens. In the past with an ordinary apparatus for making printing plates, a plano-light source was used as the illuminating light source, such as a halogen lamp or fluorescent lamp. The light passed through the subject material and was incident on a lens, but because only an extremely small portion of the light was incident on the lens, and because of insufficient light, or light not complying with the required wave-length, proper exposure was not possible. Even if the light passed through the lens, the image would not come out at all or it took a time and the resulting image was blurred and of poor quality and was completely unusable for exposing the plate. For that reason a close contact method has been employed for selectively hardening the lightsensitive coating by directly exposing the entire subject to light from a light source which has not been passed through a iens.Therefore at present a negative or positive has to be retaken by means of a camera, to agree with the pre-determined quality needed for close contact work. A main object of this invention is to expose directly any kind of printing plate, or film usable in brightly-lit rooms, using an apparatus which eliminates the need to make a negative or positive film of the same proportional size and then to place that film in close contact in order to make a printing plate or film of the same size. According to the invention there is provided a direct method of making printing plates or film usable in brightly-lit rooms, in which a light source is disposed on the optical axis inside an enclosure, the light from the light source is condensed and intensified by a lens system and is passed through an appropriate filter, then through a subject transparency and then passes through a lens with a shutter onto a printing plate or a film which is held stationary, said plate or film being thereby exposed by a powerful uniform light which conforms to the wave-length response of the photosensitive material. An embodiment of the invention will now be described, by way of example, with reference to the accompanying drawing which is a diagrammatic view of the operation of the method of the invention. The figure shows an apparatus for making a printing plate in which there is a high density mercury light source 2 disposed on the optical axis of the body of an enclosure 1. The light from the light source 2 is rendered convergent by a first lens 3 which is in an adjustable unrestricted position, and is then further condensed and intensified by a second, large aperture lens 4 such as a condenser lens or a Fresnel lens. Alternatively, a single condenser lens can be used to reduce the distance from the light source to the lens. The light which has passed through the lens or lenses then passages through an appropriate filter, through the subject material 6, then through lens 8 with a shutter 7, and is incident on one of a variety of printing plates or film 10 usable in brightly-lit rooms or the like, which is held stationary by suction or the like to a board 9. A powerful uniform light source complying accurately to the appropriate wave-lengths of the photosensitive material is thus provided. In the past in close contact hardening of the sensitive layer with incident light, the source of light was made as small as possible, e.g. a point source. Moreover a strong light was desirable. In cases of when photographing or when evenly dispersing the light for use as an incident light, the ideal way is to further converge and condense the light source by passing it through a photographic lens. For such a purpose, the ideal source of light wouid be a high density mercury source which is strong in ultraviolet radiation, a metal halide source or a xenon lamp. A watercooled mercury source is particularly effective. Furthermore when there are a lot of intermediate steps, errors are cumulative, and the product is bad. Therefore simplification of this process is a required condition for producing a good product. In this invention, the method employs an apparatus which can be readily set up. Thus errors from intermediate steps do not occur and a printing plate or film can be made immediately with this direction method. With this apparatus there is less absorption of light and so a uniform light suitable for film usable in brightly-lit rooms, or one of a variety of printing plates, is passed through the appropriate filter 5, the subejct transparency 6, through the lens 8 with the shutter 7, on to one of a variety of printing plates 10, for example an offset printing plate, a letterpress (relief) resin printing plate, a screen printing plate, or film usable in brightly-lit rooms or the like, which light sensitive material is held stationary by suction or the like to the board 9. The light from the light source which has been rendered convergent and dispersed through lenses 3 and 4 using filter 5 and passes through the subject material 6. The uniform illumination of the subject material is then condensed by lens 8 accurately and sufficiently to expose the plate in conformity to the wave-length response of the photosensitive material. Thus it is possible to make a printing plate or film directly by heatsetting using a lens without requiring the making of a film for close contact, thereby reducing cost for material, iabour and the loss of time. Claims

1. A direct method of making printing plates or film usable in brightly-lit rooms, in which a light source is disposed on the optical axis inside an enclosure, the light from the light source is condensed and intensified by a lens system and is passed through an appropriate filter, then through a subject transparency and then passes through a lens with a shutter onto a printing plate or a film which is held stationary, said plate or film being thereby exposed by a powerful uniform light which confc -ms to the wave-length response of the photosensitive material.

2. A method according to Claim 1, wherein the light from the light source is condensed by a condenser lens system consisting of a plurality of condenser lenses.

3. A method according to Claim 1, wherein the light from the light source is condensed by a single condenser lens.

4. A direct method of making printing plates or film, substantially as herein described with reference to the accompanying drawing.