Contact printing apparatus and method

Claim 2

Contact printing apparatus comprising: a surface defining a zone for contact printing, means for securing a photosensitive sheet upon said surface and a negative in face-to-face abutment with said photosensitive sheet in contact with said surface, means for directing an ionized filtered stream of air in laminar flow disposition over said contact printing zone, a light source interposed above said contact printing zone, and, an enclosure at least partially overlying the contact printing zone, said enclosure including a hood of thin, flexible transparent material interposed between the light source and the sheets to be exposed, said hood operating to shield the contact printing zone from falling dust and at the same time vibrating on the laminar flow air stream to nullify the effects of shadows produced by dust particles falling on the hood.

Claim 5

A contact printing apparatus for electrostatically pinning a photosensitive sheet and at least one negative to a surface and in face-to-face disposition with each other preparatory to exposing said photosensitive sheet to light rays through each said negative comprising: an insulative plate, means for directing a stream of filtered, ultra-clean air in laminar flow disposition over one surface of said insulative plate in a predetermined direction substantially parallel to said surface so as to sweep the zone above said insulative plate with unidirectional ultra-clean air, electrostatic discharge means for generating ions of both polarities within the laminar flow air stream so that both positive and negative ions permeate the ultra-clean air zone, means for applying with respect to ground a unidirectional high voltage to the opposite surface of said insulative plate, applicator means coupled to ground for contacting the outermost surface of said photosensitive sheet and each said negative as they are respectively placed in successive abutment with the first surface of said insulative plate and with each other, and means for directing light rays through each said negative to expose the photosensitive sheet in pinned disposition therewith, whereby the ionized laminar flow air stream (1) cleanses the photosensitive sheet and each negative prior to pinning, (2) acts to support the electrostatic holding forces maintaining the photosensitive sheet and each negative in pinned disposition during exposure to the light rays, and (3) provides a static-free environment during separation of the photosensitive sheet from each said negative.

Claim 6

A contact printing apparatus for electrostatically pinning a photosensitive sheet and at least one negative to a surface and in face-to-face disposition with each other preparatory to exposing said photosensitive sheet to light rays through each said negative comprising: an insulative plate, means for directing a stream of filtered, ultra-clean air in laminar flow disposition over one surface of said insulative plate in a predetermined direction substantially parallel to said surface so as to sweep the zone above said insulative plate with unidirectional ultra-clean air, electrostatic discharge means for generating ions of both polarities within the laminar flow air stream so that both positive and negative ions permeate the ultra-clean air zone, means for applying with respect to ground a unidirectional high voltage to the opposite surface of said insulative plate, applicator means coupled to ground for contacting the outermost surface of said photosensitive sheet and each said negative as they are respectively placed in successive abutment with the first surface of said insulative plate and with each other, and means for directing light rays through each said negative to expose the photosensitive sheet in pinned disposition therewith, whereby the ionized laminar flow air stream (1) cleanses the photosensitive sheet and each negative prior to pinning, (2) acts to support the electrostatic holding forces maintaining the photosensitive sheet and each negative in pinned disposition during exposure to the light rays, and (3) provides a static-free environment during separation of the photosensitive sheet from each said negative.

Claim 7

the apparatus of claim 3 wherein said electrostatic discharge means comprises an area static eliminator.

Claim 8

The apparatus of claim 4 wherein said area static eliminator emits ions along a path co-directional with the laminar flow stream.

Claim 9

The apparatus of claim 3 wherein a light source is interposed above the contact printing zone.

Claim 10

Apparatus for contact printing comprising: an insulative plate having first and second surfaces, means for directing a filtered stream of ultra-clean ionized air in laminar flow disposition unidirectionally over the first surface, electrostatic means for pinning a photosensitive sheet and at least one negative sheet upon said first surface and in electrostatically pinned disposition with each other, said electrostatic means including a unidirectional high voltage having one side coupled to the second surface of said insulative plate and means constituting a conductive path from the other side of said unidirectional high voltage to an outboard surface of a sheet whose other face is in pinned disposition with the first surface of said insulative plate, and a light source for exposing the photosensitive sheet through each said negative sheet, aNd means for generating ions of both polarities within the laminar flow air stream so that both positive and negative ions permeate the ultra-clean air zone and reinforce electrostatic pinning forces.

Claim 11

Apparatus for contact printing comprising: an insulative plate having first and second surfaces, means for directing a filtered stream of ultra-clean ionized air in laminar flow disposition unidirectionally over the first surface, electrostatic means for pinning a photosensitive sheet and at least one negative sheet upon said first surface and in electrostatically pinned disposition with each other, said electrostatic means including a unidirectional high voltage having one side coupled to the second surface of said insulative plate and means constituting a conductive path from the other side of said unidirectional high voltage to an outboard surface of a sheet whose other face is in pinned disposition with the first surface of said insulative plate, and a light source for exposing the photosensitive sheet through each said negative sheet, aNd means for generating ions of both polarities within the laminar flow air stream so that both positive and negative ions permeate the ultra-clean air zone and reinforce electrostatic pinning forces.