ELECTROSTATIC REGISTRATION FOR CONTACT PRINTING

• US 3,661,457 A
• Filed: 03/06/1970
• Issued: 05/09/1972
• Est. Priority Date: 03/06/1970
• Status: Expired due to Term

• Current Assignee: Roger A. Frech
• Original Assignee: Roger A. Frech
• Inventors: Frech, Roger A.
• Primary Examiner(s): Matthews, Samuel S.
• Assistant Examiner(s): Wintercorn, Richard A.
• Application Number:
  US05/017,244
• Time in Patent Office: 795 Days
• Field of Search: 355/3,4,12,16,31,78,79,98,99,103,72,75
• US Class Current: 355/78
• CPC Class Codes: G03B 27/08 for automatic copying of several originals one after the other, e.g. for copying cinematograph film
• CPC Class Codes: G03B 27/18 Maintaining or producing contact pressure between original and light-sensitive material

Abstract

A contact printing apparatus for accurately and precisely maintaining in registry a master image-bearing transparent film and a light-sensitive duplicate. In one embodiment, the master and duplicate comprise two film strips being initially wound on separate supply reels and transported through an exposure zone to take-up reels by a drive mechanism. A pair of high voltage rollers are disposed upstream of the exposure zone in contact with the moving master and duplicate so as to electrostatically charge them causing strong attraction and adherence therebetween. A discharge device is provided downstream of the exposure zone so as to prevent any scintillation when the master and duplicate are separated.

Claims

1. In a contact printing apparatus comprising means for supporting an image-bearing master film and a light-sensitive duplicate, means for exposing the master and duplicate in a planar zone, and means for moving the master and duplicate throuGh the exposure zone, the provision of:

means in the path of movement of said master and duplicate prior to said exposure zone for bringing said master and duplicate into contact with each other and electrostatically charging at least one of the master and duplicate while in said contact to cause attraction and adherence therebetween during exposure thereof, said means including a frame, a source of d.c. voltage, and a pair of spaced apart electrically conductive rollers supported by said frame so as to contact the outer surfaces of said master and duplicate, at least one of said rollers connected to said voltage source to create a potential between said rollers, said rollers being arranged in spaced relation with respect to one another so as to prevent sparkover across the air path between the portions of the oppositely charged rollers in closest spaced relation.

2. In a contact printing apparatus comprising means for supporting an image-bearing master film and a light-sensitive duplicate, means for exposing the master and duplicate in a planar zone, and means for moving the master and duplicate through the exposure zone, the provision of:

means for electrostatically charging at least one of the master and duplicate to cause attraction and adherence therebetween during exposure thereof, said means including a frame, a source of d.c. voltage, and a pair of spaced apart electrically conductive rollers supported by said frame so as to contact the outer surfaces of said master and duplicate, at least one of said rollers connected to said voltage source to create a potential between said rollers, said rollers being arrayed in opposed spaced relation on opposite sides of said master and duplicate, said rollers having a width less than the width of said master and duplicate, said rollers having ends spaced inwardly from the edges of said master and duplicate so as to increase the length of the air path between said roller ends to prevent sparkover thereacross.

3. The provision of claim 1 wherein said rollers are arranged in longitudinally spaced relation.

4. In a contact printing apparatus comprising means for supporting an image-bearing master film and a light-sensitive duplicate, means for exposing the master and duplicate in a planar zone, and means for moving the master and duplicate through the exposure zone, the provision of:

means for electrostatically charging at least one of the master and duplicate to cause attraction and adherence therebetween during exposure thereof, said means including a source of d.c. voltage, a pair of spaced apart electrically conductive rollers supported by said frame so as to contact the outer surfaces of said master and duplicate, at least one of said rollers connected to said voltage source to create a potential between said rollers, said rollers being arranged in spaced relation with respect to one another so as to prevent sparkover across the air path between the portions of the oppositely charged rollers in closest spaced relation, and means for biasing the master and duplicate outer surfaces in contact with said roller.

5. In a contact printing apparatus comprising means for supporting an image-bearing master film and a light-sensitive duplicate, means for exposing the master and duplicate in a planar zone, and means for moving the master and duplicate through the exposure zone, the provision of:

means for electrostatically charging at least one of the master and duplicate to cause attraction and adherence therebetween during exposure thereof, said means including a frame, a source of d.c. voltage, a pair of spaced apart electrically conductive rollers supported by said frame so as to contact the outer surfaces of said master and duplicate, at least one of said rollers connected to said voltage source to create a potential between said rollers, said rollers arranged in spaced relation with respect to one another so as to prevent sparkover across the air path between the portions of the oppositely charged rollers in closest spaced relation, and means for discharging a longitudinal portion of said master and duplicate after said portion thereof has passed through said exposure zone so as to prevent scintillation when said master and duplicate are separated thereby precluding inadvertent exposure of said light-sensitive duplicate.

6. The contact printing apparatus of claim 5 wherein said means for discharging said master and duplicate comprises an a.c. voltage source coupled to a pair of contact rollers, said source providing a peak voltage substantially equal to said d.c. voltage.

7. In a contact printing apparatus comprising supply means for supplying image-bearing transparent master and light-sensitive duplicate continuous strips and take-up, means for taking up said master and duplicate strips, means for moving the strips from the supply means to the take-up means, and means for exposing the film strips in a planar zone, the provision of:

means in the path of movement of said master and duplicate prior to said exposure zone for bringing said master and duplicate into contact with each other and electrostatically charging at least one of said strips while in said contact to cause attraction and adherence therebetween during exposure thereof, said means including a frame, a source of d.c. voltage, and a pair of spaced apart electrically conductive rollers supported by said frame so as to receive the strips therebetween in contact with the outer surfaces thereof, at least one of said rollers connected to said voltage source to create a potential difference between the rollers, said rollers being spaced so as to prevent arcing across the air path between the portions of the rollers in closest spaced relation.

8. The provision of claim 7 wherein said rollers are spaced apart in the general direction of movement of said master and duplicate and on opposite sides of said master and duplicate.

9. In a contact printing apparatus comprising supply means for supplying image-bearing transparent master and light-sensitive duplicate continuous strips and take-up means for taking up said master and duplicate strips, means for moving the strips from the supply means to the take-up means, and means for exposing the film strips in a planar zone, the provision of:

means for electrostatically charging said strips to cause attraction and adherence therebetween during exposure thereof, said means including a frame, a source of d.c. voltage, and a pair of spaced apart electrically conductive rollers supported by said frame so as to receive the strips therebetween in contact with the outer surfaces thereof, at least one of said rollers connected to said voltage source to create a potential difference between the rollers, said rollers being spaced apart so as to prevent arcing across the air path between the portions of the rollers in closest spaced relation, said rollers having a width less than the width of said master and duplicate strips so as to be spaced inwardly from the edges of said master and duplicate strips to increase the length of the air path between the roller ends so as to prevent arcing.

10. The provision of claim 1 wherein said rollers are arranged in opposed relation on opposite sides of said master and duplicate, at least one of aid rollers having a width less than the width of at least one of said master or duplicate and having its strip-contacting edges spaced inwardly from the edges of said one strip so as to increase the length of the air path between the ends of the opposed rollers.

11. The provision of claim 7 wherein at least one of said rollers has a width less than the width of at least one of said master or duplicate strips and has its strip-contacting edges spaced inwardly from the edges of said one strip to increase the length of the air path between the ends of the opposed rollers to prevent arcing.