GB2190758A - A copying process using a thermosensitive recording substance - Google Patents

Abstract

A copying process comprises a irradiating with light a surface which bears material to be copied (3, a1, a2 and a3) to form an image of said surface on the surface of a thermosensitive recording substance comprising a diazo compound and a coupler therefor (4) whereby to form a latent image (c1, c2 and c3) on the thermosensitive recording substance of the original and heating the entire surface of said thermosensitive recording substance whereby to form a visible image in those areas shielded from the light by the original (3). <IMAGE>

Description

SPECIFICATION A copying process using a thermosensitive recording substance This invention relates to a copying process using a thermosensitive recording substance having a thermosensitive layer thereon made of fixable thermosensitive diazo materials.

In recent years, thermosensitive recording apparatuses using thermosensitive coloring leuco materials have been developed in the fields of facsimiles and printers. These recording apparatuses are inferior in that the coloring materials continue to develop even after the recording process has been completed when the recording substance on which an image has been formed is handled in a specific way, for example, when it is heated or when it contacts solvents, resulting in damage to the image, which causes difficulties in correction and/or alteration of the image.

In order to prevent the coloring of the portion of the recording substance other than the image thereon, a recording process has been proposed in which a recording substance having a thermosensitive material thereon composed of diazo compounds, coupling agents and coloring additives is heat-treated to form a latent image and then exposed to light to thereby decompose the diazo compounds that have not reacted with the coupling agents so that the coloring of the portion of the recording substance other than the image thereon can be prevented.

The apparatuses having such a thermosensitive material are used only in fixable and thermosensitive printers in which a recording substance is heat-treated by a thermosensitive head based on an original document to form a latent image on the recording substance in the same manner as that of a common thermosensitive printer, and then exposed to light to thereby fix the portion of the recording substance other than the latent image.

The copying process of this invention, which overcomes the above-discussed and numerous other disadvantages and deficiencies of the prior art, comprises irradiating with light a surface which bears material to be copied to form an image of said surface on a thermosensitive recording substance whereby to form a latent image on the thermosensitive recording substance of the material to be copied and to fix the area of the thermosensitive recording substance which does not form part of said latent image and heating the entire surface of said thermosensitive recording substance on which said image of the surface bearing material to be copied was formed whereby to render said latent image visible, said thermosensitive recording material comprising a diazo-compound and a coupler therefor.

In one embodiment, the surface which bears material to be copied is light-permeable irradiating light passing through said surface to form said image on said thermosensitive recording substance.

In another embodiment, the surface which bears material to be copied is light-reflectable and is which said irradiating light is reflected from said surface which bears material to be copied to form said image on said thermosensitive recording substance.

The diazo-compound and coupling agent therefor may be any of those already known in the art as being suitable for use in thermosensitive recording substances. The thermosensitive recording substance may also comprise any of the colouring agents known to be useful in thermosensitive recording substances.

The thermosensitive recording substance is preferably formed as a layer on a support such as paper or a synthetic plastics film.

The surface which bears material to be copied may be integral with or formed on a substrate, the substrate being light-permeable when the said surface is light-permeable. The surface may, for example, be that of a printed document or paper or plastics film upon which legends, designs, etc. are reproduced. The plastics film may be transparent or translucent and the legends, design or pattern reproduced thereon, opaque.

The method of the present invention (1) provides a copying process by means of which, for example, a fixable thermosensitive sheet comprising or having a layer of thermosensitive recording substance thereon said substance comprising thermosensitive diazo materials can be used in a copying apparatus, thereby attaining an enlargement of the range of use of the said fixable thermosensitive sheet; (2) provides a simplified copying process in which the above-mentioned fixable thermosensitive sheet is exposed to light transmitted through or reflected from an original document to be copied to form a latent image thereon and to fix the portion of the sheet other than the said latent image, and then the entire area of the sheet is heated to make the latent image visible, and accordingly the original image can be readily copied; and (3) provides a simplified copying process in which, since not only the light-exposing step is attained by exposing the entire area of the thermosensitive layer to light via the original document, but also the heating step succeeding the light-exposing step is attained by heating the entire area of the thermosensitive layer, the structure required for the said copying process becomes simple, so that the said copying process can be carried out with a simplified and compact copying machine.

This invention will be further illustrated and its numerous objects and advantages will become apparent to those skilled in the art by reference to the accompanying drawings in which: Figure 1 is a schematic diagram illustrating a copying process of the present invention in which the surface (and its substrate) which bears material to be copied is light-permeable; Figure 2 is a schematic diagram illustrating the light-exposing step of the embodiment of Fig. 1; Figure 3 is a schematic diagram illustrating the heating step of the embodiment of Fig. 1.

Fig. 1 shows a copying process of this invention, in which a surface which bears material to be copied is embodied in an original document 3 disposed on a thermosensitive recording substance 4 which document, together with the thermosensitive recording substance 4 is moved by rollers 5 and 6 beneath a light-exposing system 1 having a lamp 2 in a manner to maintain the document in contact with the thermosensitive recording substance 4. The original document 3 is a light-permeable sheet on which patterns, letters, etc., have been recorded. The thermosensitive recording substance 4 is composed of a support 4a (Fig. 2) made of paper, a synthetic resin film or the like, which has a thermosensitive layer 4b thereon containing diazo compounds, coupling agents and colouring additives.

A separating means 7 functioning to separate the thermosensitive recording substance 4 from the original document 3 is disposed downstream of the light-exposing system 1 with respect to the direction of movement of the original document 3 and the thermosensitive recording substance 4. A heating roller 8 functioning to heat the entire area of the thermosensitive layer 4b is disposed downstream of the separating means 7 in contact with a carrying roller 9.

With an apparatus having the above-mentioned structure, one embodiment of the copying process of this invention is carried out as follows: As shown in Fig. 2, the thermosensitive recording substance 4 is exposed to light by the light-exposing system 1 through the original document 3 disposed on the thermosensitive layer 4b of the thermosensitive recording substance 4. The original document 3 is constituted by opaque portions a1, a2 and a3 corresponding to the recorded patterns and/or letters and light-permeable portions bl, b2 and b3.When the original document 3 is irradiated with light I from the lamp 2, the opaque portions a1, a2 and a3 act as a barrier to the light I, but the light-permeable portions b1, b2 and b3 permit transmission of the light therethrough so that light energy cannot be supplied to the portions c1, c2 and c3 of the thermosensitive layer 4b corresponding to the opaque portions a1, a2 and a3 of the original document 3 whereas light energy can be supplied to the other portions of the thermosensitive layer 4b corresponding to the light-permeable portions b1, b2 and b3 of the original document 3, resulting in the formation of a latent image on the thermosensitive layer 4b that corresponds to the opaque portions a1, a2 and a3 of the original document 3.This is because the diazo compounds, in the portions of the thermosensitive layer 4b corresponding to light-permeable portions b1, b2 and b3 of the original document 3 that have been irradiated with transmitted light are thereby decomposed so that they are no longer capable of coupling with the coupling agents and the colouring of the said diazo compounds by subsequent application of heat is prevented (i.e., the fixation of the portions other than the latent image is attained). On the other hand, the diazo compounds in the portions c1, c2 and c3 of the thermosensitive layer 4b, which have not been irradiated with light, remain capable of coupling with the coupling agents resulting in the formation of a latent image which can be made visible by the application of heat thereto.

After the above-mentioned light-exposing step is carried out by the light-exposing system 1, the thermosensitive recording substance 4 is moved by the rollers 5 and 6 from the location of the light-exposing system 1 to the heating roller 8 via the separating means 7. The heater-roller 8 heats the entire area of the thermosensitive layer 4b of the thermosensitive recording substance 4. As shown in Fig. 3, since the diazo compounds in the portions c1, c2 and c3 of the thermosensitive layer 4b remain capable of coupling with the coupling agent, they become coloured by the 'heating-treatment provided by contact with the heating roller 8.The diazo compounds in the other portions of the thermosensitive layer 4b have been decomposed by the light-exposure as mentioned above, and even when they are heat-treated by the heating roller 8, they do not become coloured at all, and the end result is a visible image corresponding to the latent image.

Whilst the above-described embodiment concerns a process in which a light-permeable original document 3 is transferred together with the thermosensitive recording substance 4 in a manner to contact said document with the said thermosensitive recording substance 4, this invention is, of course, applicable to a process in which an original document is irradiated with light and the reflected light therefrom is used to form an image thereof on the thermosensitive recording substance 4, for example in the manner as that employed in a common copying machine.

It is understood that various other modifications will be apparent to and can be readily made by those skilled in the art without departing from the scope and spirit of this invention.

Claims (8)

1. A copying process which comprises irradiating with light a surface which bears ma terial to be copied to form an image of said surface on the surface of a thermosensitive recording substance whereby to form a latent image on the thermosensitive recording substance of the material to be copied and to fix the area of the thermosensitive recording substance which does not form part of aid latent image and heating the entire surface of said thermosensitive recording substance on which said image of the surface bearing material to be copied was formed whereby to render said latent image visible, said thermosensitive recording material comprising a diazo-compound and a coupler therefor.

2. A copying process as claimed in claim 1, in which the surface which bears material to be copied is light-permeable irradiating light passing through said surface to form said image on said thermosensitive recording substance.

3. A copying process as claimed in claim 1, in which the surface which bears material to be copied is light-reflectable and in which said irradiating light is reflected from said surface which bears material to be copied to form said image on said thermosensitive recording substance.

4. A copying process as claimed in any of claims 1 to 3, in which the thermosensitive recording substance comprises a colouring additive.

5. A copying process as claimed in claims 2 or 3, in which the thermosensitive recording substance is formed as a layer on a support.

6. A copying process as claimed in claim 5, in which the support is paper or a synthetic plastics film.

7. A copying process as claimed in any of claims 1 to 6, in which the surface which bears material to be copied is integral with or formed on a substrate, the substrate being light-permeable when the surface is light permeable.

8. A copying process as claimed in claim 1, substantially as hereinbefore described with reference to and as illustrated in Figs. 1 to 3 of the accompanying drawings.