Extremely high speed halftone screen positioning assembly
AssigneeItek Corporation
InventorsThomas M. Madigan, Daniel H. Robbins
Life of this patent
Estimating the term…
Abstract
A contact screen positioning device supports a flexible bowed halftone screen over a vacuum platen having a sheet of film thereon so that as the positioning device moves slowly down over the vacuum platen, central portions of the contact screen initially press against central portions of the platen and less and less centralized portions thereafter sequentially press against less and less centralized portions of said vacuum platen, to produce a rapid sweeping of air toward outer portions of the platen for rapid positioning of said screen over said platen without entrapped air pockets being formed between the screen and the film on the platen.
Claims33
A contact screen positioning assembly for positioning a flexible contact screen with respect to a vacuum platen which is in turn positioned at the imaging plane of a camera comprising a screen position shifter including contact screen support means positioned upon said screen position shifter for supporting said flexible contact screen and causing said screen to assume a bowed shape before being pressed against said vacuum platen, said screen shifter being movable with respect to said vacuum platen for initially causing central portions of said contact screen to contact central portions of said platen and for thereafter sequentially causing less and less centralized portions of said contact screen to contact less and less centralized portions of said platen.
A contact screen positioning assembly for positioning a flexible contact screen with respect to a vacuum platen which is in turn positioned at the imaging plane of a camera comprising a screen position shifter movable with respect to said vacuum platen for initially causing central portions of said contact screen to contact central portions of said platen and for thereafter sequentially causing less and less centralized portions of said contact screen to sequentially contact less and less centralized portions of said platen, said screen shifter further including contact screen support means positioned upon said screen position shifter for supporting said contact screen, said contact screen support means further comprising a first contact screen support member positioned at one portion of said shifter and a second contact screen support member positioned at another portion thereof, each of said contact screen support members comprising an elongated slot having a stud member held within said slot, said stud member having a head portion thereof which prevents said stud from falling out of said slot, said stud further having a weight member affixed to a lower portion thereof for maintaining said heat portion of said stud in contact with the upper portion of said slot when said screen position shifter assumes a position whereby said contact screen is not contacting the surface of said vacuum platen together with spring means coupled to said stud for mechanically biasing said stud against an inner terminal portion of said elongated slot.
A contact screen positioning assembly for positioning a flexible contact screen over a vacuum platen which is in turn positioned at the imaging plane of a camera comprising:
- a. a screen position shifter movable with respect to said vacuum platen for initially causing central portions of said contact screen to contact central portions of said platen and for thereafter sequentially causing less and less centralized portions of said contact screen to sequentially contact less and less centralized portions of said platen;
- b. contact screen support means including a first contact screen support member positioned at one portion of said screen shifter and a second contact screen support member positioned at another portion thereof, together with biasing means for urging said screen support members inwardly toward central portions of said screen shifter;
- and
- c. motion control means for permitting outward motion of said screen support members without substantial tipping thereof as said screen shifter approaches said platen.
A contact screen positioning assembly for positioning a flexible contact screen over a vacuum platen which is in turn positioned at the imaging plane of a camera comprising:
- a. a screen position shifter movable with respect to said vacuum platen for initially causing central portions of said contact screen to contact central portions of said platen and for thereafter sequentially causing less and less centralized portions of said contact screen to sequentially contact less and less centralized portions of said platen;
- b. a first carriage means slidably coupled to a first portion of said screen shifter and a second carriage means slidably coupled to a second portion of said screen shifter;
- c. mounting means for coupling a first portion of said screen to said first carriage means and a second portion of said screen to said second carriage means;
- d. carriage spring means coupled to said first and second carriage means for biasing said first and second carriage means in a direction toward centralized portions of said screen shifter;
- and
- e. pad means mounted upon said first and second carriage means and coupled to said screen for causing the extremities of said screen to become flattened as said pad means presses against the surface of said platen.
A contact screen positioning assembly for positioning a flexible contact screen over a horizontal vacuum platen which is in turn positioned at the imaging plane of a camera comprising:
- a screen position shifter vertically movable with respect to said horizontal vacuum platen for supporting said contact screen against gravity so that said contact screen assumes a bowed shape over major portions thereof and for causing central portions of said contact screen to initially contact central portions of said platen and for thereafter sequentially causing less and less centralized portions of said contact screen to sequentially contact less and less centralized portions of said platen, said screen position shifter further including contact screen support means positioned upon opposite sides of said screen position shifter for causing outer portions of said screen coupled thereto to push said contact screen support means away from centralized portions of said vacuum platen during contact of said screen with said platen.
Dependencies are inferred from the claim text.