Photographic exposure apparatus

Abstract

A portable photographic exposure apparatus for making reproductions of loft drawings, body drafts or the like directly from the drawing table on which the drawing is made. A wheeled cabinet structure has a horizontal supporting surface, the height of which is adjustable to the height of a drawing table, with an exposure unit adapted to be mounted on the supporting surface and containing a light source, a set of electric motor driven wheels, and a source of static electricity. The exposure unit is driven over the drawing table to expose a sheet of film which is laid over the drawing on the drawing table to reproduce the drawing. Static electricity projected by the exposure unit presses the film firmly against the drawing to be reproduced. The electric motor is reversible to return the exposure unit to its supporting cabinet. The apparatus may also be used to expose a negative which is subsequently processed to provide positive reproductions of the loft drawing.

What I claim as my invention is: 
     
       1. Exposure apparatus for making a photographic reproduction of a loft drawing or the like supportably overlying a horizontal drawing table surface, comprising a box-like .[.structure.]. .Iadd.unit .Iaddend.having an open bottom and containing a light source, a set of wheels on said .[.structure.]. .Iadd.unit .Iaddend.on which same is movable over a sheet of light sensitive exposure film covering the drawing to be reproduced, an electrostatic discharge means extending along the leading edge of said exposure unit and constructed to direct an electrostatic charge toward said film and drawing to thereby adhere the film horizontally and smoothly to the drawing as said exposure unit moves thereover to expose said film, a motor for driving said wheels to propel said exposure unit over said film, means for electrically grounding the drawing, and control means for energizing said light source, said motor and said electrostatic discharge means. 
     
     
       2. Apparatus according to claim 1 wherein said electrostatic discharge means comprises an electrode extending along the leading edge of said exposure unit and having a series of spaced, downwardly extending discharge pins thereon. 
     
     
       3. Apparatus according to claim 1 including means extending along the trailing edge of said exposure unit for dissipating the electrostatic charge between the drawing and the exposed film. 
     
     
       4. Apparatus for photographically exposing film overlying a loft drawing or the like, comprising a housing having exposure lighting means, means moving said housing and said drawing with the overlying film relative to each other in close juxtaposition for progressive exposure of said film, .[.and.]. said housing carrying an elongated electrostatic discharge means ahead of said lighting means for progressively directing an electrostatic flux field to said film and drawing to adhere same together during exposure, and means for progressively dissipating electrostatic charge from said film and drawing following exposure to facilitate separation of said film from said drawing. 
     
     
       5. The apparatus as defined in claim 4 and in which said drawing and film are supported flat on a drawing table surface, and said means moving said housing comprises means driving same over the surface of said table from one end to the other of said drawing. 
     
     
       6. The apparatus as defined in claim 4 and in which said housing comprises a box-like structure having an open bottom of a length to overextend the width of said film, said lighting means being carried in said housing and adapted to direct exposure light from the open bottom onto said film immediately subsequent to electrostatic adherence thereof to said drawing as said housing is moved thereover. .Iadd. 7. Exposure apparatus for making a photographic reproduction of a loft drawing or the like supportably overlying a horizontal drawing table surface, comprising a box-like unit having an open bottom and containing a light source, a set of wheels on said unit on which it is movable over a sheet of light sensitive exposure film covering the drawing to be reproduced, a means for applying a downward force proximate the leading edge of said exposure unit and adapted to apply such force toward said film and drawing to cause the film horizontally and smoothly to adhere to the drawing as said exposure unit moves thereover to expose said film, and a motor for driving said wheels to propel said exposure unit over said film. .Iaddend..Iadd. 8. The combination as set forth in claim 7 wherein said downward force applying means is spaced forwardly of the forwardmost of said set of wheels and a means is operably connected to said downward force applying means for interrupting the downwardly applied force from said film and drawing subsequent to passage of said exposure unit. .Iaddend..Iadd. 9. The combination as set forth in claim 8 wherein said downward force applying means comprises an electrostatic discharge electrode supported forwardly of said unit and wherein said means for dissipating said charge comprises a pad of electrical insulating material for dissipating such charge. .Iaddend..Iadd. 10. The combination as set forth in claim 9 wherein there is further positioned at the forward edge of said unit a wiper member weighted to engage the film and drawing and to press out in advance any air pockets that may exist therebetween. .Iaddend. .Iadd. 11. The combination as set forth in claim 10 wherein said exposure unit includes a plurality of longitudinal light tubes extending transversely relative to the path of movement of said unit. .Iaddend..Iadd. 12. Exposure apparatus for making a photographic reproduction of a loft drawing or the like supportably overlying a horizontal drawing table surface, comprising a box-like unit having an open bottom and containing a light source, a plurality of wheels on said unit on which it is movable over the surface of a sheet of light sensitive exposure film covering the drawing to be reproduced, means for providing a downward force along the leading edge of said exposure unit to cause the film and drawing to be pressed together and to the drawing table surface, a motor for driving the said wheels to propel said exposure unit over said film, and variable speed controls operatively connected to and controlling the operation of said motor for controlling the exposure time of the apparatus. .Iaddend. .Iadd. 13. Exposure apparatus for making a photographic reproduction of a loft drawing or the like supportably overlying a horizontal drawing table surface, comprising a box-like unit having an open bottom and containing a light source, a plurality of wheels on said unit on which it is movable over the surface of a sheet of light sensitive exposure film covering the drawing to be reproduced, means for providing a force along the leading edge of said exposure unit to cause the film and drawing to be pressed together and to the drawing table surface, a motor for driving the said wheels to propel said exposure unit over said film, and variable speed controls operatively connected to and controlling the operation of said motor for controlling the exposure time of the apparatus. .Iaddend..Iadd. 14. Exposure apparatus for making a photographic reproduction of a loft drawing or the like supportably overlying a horizontal drawing table surface, comprising a box-like unit having an open bottom and containing a light source, a plurality of wheels on said unit on which it is movable over the surface of a sheet of light sensitive exposure film covering the drawing to be reproduced, means for providing a force to cause the film and drawing to be pressed together and to the drawing table surface, a motor for driving the said wheels to propel said exposure unit over said film, and variable speed controls operatively connected to and controlling the operation of said motor thus controlling the exposure time of the apparatus. .Iaddend.