Flow camera for large document reproductions

• US 5,341,192 A
• Filed: 03/02/1993
• Issued: 08/23/1994
• Est. Priority Date: 03/02/1993
• Status: Expired due to Fees

• Current Assignee: Black & Veatch Corporation
• Original Assignee: Black & Veatch Architects, Inc.
• Inventors: Pace, Herbert W., Wally, Joseph H. Jr.
• Primary Examiner(s): Hayes, Monroe H.
• Application Number:
  US08/025,444
• Time in Patent Office: 539 Days
• Field of Search: 355/50, 355/51
• US Class Current: 355/50
• CPC Class Codes: G03B 27/48 with original in the form of a film strip moving continuously and compensation for consequent image movement

Abstract

A flow camera equipped with a microprocessor based control system accepts large original documents in continuous, moving fashion and photographs them through a specifically shaped slotted aperture positioned between the original document and an objective lens. The originals are illuminated during exposure simultaneously from the front and the back, recording congruent images from two-sided material such as engineering drawings on translucent media having positionally related information on both sides. The light from the underneath side, opposite the lens, not only reveals and exposes the image on the second side but it enhances the quality and sharpness of the primary image on the side toward the lens. Avoidance of image loss is accomplished by using in the optical system a single mirror which deflects the optical path substantially less than 90°. Servomotors with encoder feedback are correlated by the microprocessor to the degree of photographic reduction so that the ratio of speed between the original document and the moving strand of film is exactly equal to the reduction ratio to avoid speed induced distortion in the reduced and enhanced film image.

Claims

1. A flow camera for reproducing an image on a sheet or document such as a large engineering drawing, map, or architectural plan while the sheet is in motion, said camera comprising:

a frame presenting a slit through which light from the sheet can pass;

means for conveying the sheet at a prescribed speed along a conveyor path carrying the sheet in proximity to said slit;

front lighting means for applying light to a side of the sheet facing said slit for reflection of the light from said front lighting means off of the sheet and through said slit;

back lighting means situated such that the sheet is between said slit and back lighting means to effect transmission of light from said back lighting means through the sheet and then through said slit;

means for transporting a light sensitive medium at a speed having a selected relationship to said prescribed speed; and

optical means for focusing, on said light sensitive medium the light reflected off of the sheet and through said slit from said front lighting means and the light transmitted through the sheet and said slit from said back lighting means.

2. A flow camera as set forth in claim 1, including:

first and second transparent plates; and

means on said frame for supporting said first and second plates apart from one another along said conveyor path at a location and orientation to allow the sheet to pass between said plates while maintaining the sheet in a plane parallel to the plane containing said slit, whereby the light from said front lighting means can pass through said first plate to reach the sheet and the light from said back lighting means can pass through said second plate to reach the sheet.

3. A flow camera as set forth in claim 2, wherein said conveying means includes a plurality of moving entry belts for feeding the sheet between said transparent plates and a plurality of moving discharge belts for pulling the sheet out of the space between said transparent plates, said discharge belts being spaced downstream from said entry belts to avoid blocking light emitted from said back lighting means toward the sheet as it passes between said transparent plates.

4. A flow camera as set forth in claim 3, including:

a pair of entry guides spaced apart from one another and arranged to receive the sheet from said entry belts and guide the sheet into the space between said transparent plates; and

a pair of discharge guides spaced apart from one another and arranged to receive the sheet from the space between said transparent plates and guide the sheet toward said discharge belts.

5. A flow camera as set forth in claim 4, wherein:

said entry belts include a first set of belts and a second set of belts arranged to engage opposite surfaces of the sheet to propel it along said conveyor path, each set of entry belts including a plurality of belts spaced apart from one another in a direction transverse to the conveyor path; and

said discharge belts include a first set of belts and a second set of belts arranged to engage opposite surfaces of the sheet to propel it along said conveyor path, each set of discharge belts including a plurality of belts spaced apart from one another in a direction transverse to the conveyor path.

6. A flow camera as set forth in claim 5, including a plurality of spaced apart fingers on said entry guides extending between the belts in both sets of entry belts.

7. A flow camera as set forth in claim 1, wherein said conveying means comprises:

a plurality of moving entry belts comprising opposing sets of belts each including a plurality of belts which move adjacent to the opposing belts to convey the sheet along said conveyor path; and

a plurality of moving discharge belts comprising opposing sets of belts spaced downstream from the entry belts and each including a plurality of belts which move adjacent to the opposing belts to convey the sheet along said conveyor path.

8. A flow camera as set forth in claim 7, including a curved belt support plate on the frame for said entry belts and another curved belt support plate for said discharge belts, said belt support plates being located and arranged to guide the belts in a manner to maintain the belts in opposing sets adjacent to one another for engagement against opposite surfaces of the sheet.

9. A flow camera as set forth in claim 1, wherein:

said optical means defines an optical axis;

said slit has a longitudinal axis substantially centered on and perpendicular to the optical axis; and

said slit has opposing side edges which curve in a divergent manner away from the optical axis to define opposite end portions of the slit which are wider than a center portion adjacent to the optical axis.

10. A flow camera as set forth in claim 1, wherein:

said slit has a length dimension which is oriented substantially perpendicular to the direction of movement of the sheet along said conveyor path and which is at least as great as the width dimension of the sheet;

said front lighting means comprises a pair of elongated light sources arranged generally parallel to the length dimension of the slit and situated at locations offset substantially equidistantly on opposite sides of an optical axis defined by said optical means; and

said back lighting means comprises a single elongated light source arranged generally parallel to the length dimension of the slit and in line with said optical axis.

11. A flow camera as set forth in claim 10, wherein said slit has opposing side edges which curve in a divergent manner away from the optical axis to define opposite end portions of the slit which are wider than a center portion adjacent to the optical axis.

12. A flow camera as set forth in claim 10, including means for adjusting the intensity of said pair of light sources and means for adjusting the intensity of said single light source independently of the adjusting means for said pair of light sources.

13. A flow camera as set forth in claim 1, including means for adjusting the intensity of the light from said front lighting means and means for adjusting the intensity of the light from said back lighting means independently of the adjusting means for the front lighting means.

14. A flow camera as set forth in claim 1, wherein said optical means comprises:

a substantially light tight film compartment for housing said light sensitive medium and transporting means therefor;

an objective lens mounted on the frame in a fixed position for focusing light on said medium;

an optical tower constructed of a plurality of massive plates resistant to vibrational forces and connected to form a light tight compartment in the tower; and

a single mirror mounted in a fixed position to said massive plates within the tower and oriented to reflect light from the sheet toward said lens.

15. A flow camera as set forth in claim 14, wherein:

said optical means defines an optical axis; and

said mirror is oriented to reflect light along said optical axis through an angle less than 90°

.

16. A flow camera as set forth in claim 14, including:

a plurality of mirror support elements connected with said massive plates and defining a guide way into which said mirror can be slid to said fixed position and out of which said mirror can be slid for removal from the tower;

an access opening in one of said massive plates providing access to said mirror in the guideway; and

a removable cover normally closing said access opening in light tight fashion.

17. A flow camera as set forth in claim 1, wherein:

said light sensitive medium comprises film contained in a roll; and

said transporting means comprises power means for unrolling the film from said roll, transporting said film in a substantially planar form past an exposure station at which light from the sheet is focused on the film by said optical means, and winding the film onto a spool following exposure.

18. A flow camera as set forth in claim 17, wherein said transporting means comprises:

a rotatable spindle on which said film roll is received;

a rotatable capstan around which the film is drawn between said spindle and spool, said power means operating to rotate said spool and capstan to draw the film from said roll and wind the film onto said spool;

a pair of idlers between said spindle and capstan for maintaining the film in said substantially planar form as the film is advanced past the exposure station; and

slip means coupled with said spindle and spool for allowing slippage of the spindle and spool to accommodate variations in the diameter of the film wound on the spindle and spool.

19. In a flow camera which exposes a sheet or document such as a large engineering drawing, map, or architectural plan to light while the sheet is in motion at a prescribed speed and which has an optical system for reproducing an image on the sheet on film held in a roll, the improvement comprising:

a light tight film compartment on the camera;

a rotatable spindle in said film compartment for holding the roll of film and paying out the film;

a take up spool in the film compartment for receiving the exposed film;

a capstan mounted in said film compartment for rotation, said capstan presenting a high friction surface engaging the film between said spindle and spool to draw the film off of said roll upon rotation of the capstan;

a pair of idlers in the film compartment between said spindle and capstan, said idlers being arranged to hold the film in a planar form at an exposure station extending between the idlers for exposure of the film;

power means for driving said capstan and spool and maintaining the rotational speed of the capstan at a rate at which the film is advanced through said exposure stage at a constant speed having a selected relationship to said prescribed speed; and

slip means coupled with said spindle and spool for allowing the spindle and spool to slip to accommodate variations in the diameter of the film wound on the spindle and spool.

20. A flow camera for reproducing an image on a sheet or document such as a large engineering drawing, map, or architectural plan while the sheet is in motion, said camera comprising:

a frame presenting a slit through which light from the sheet can pass;

means for conveying the sheet at a prescribed speed along a conveyor path carrying the sheet in proximity to said slit;

lighting means for illuminating the sheet;

a single mirror for reflecting the light from the sheet;

means for transporting a light sensitive medium at a speed having a selected relationship to said prescribed speed; and

optical means for focusing the light reflecting from said mirror on said light sensitive medium.

21. A flow camera for reproducing an image on a sheet or document such as a large engineering drawing, map, or architectural plan while the sheet is in motion, said camera comprising:

a frame;

a mask plate having an elongated slit therein;

means on said frame for releaseably receiving and holding said mask plate at a fixed position and yet allowing selective removal of the mask plate from the frame;

means for conveying the sheet at a prescribed speed along a conveyor path carrying the sheet in proximity to said slit;

means for applying light to the sheet in a manner to direct the light through the slit;

means for transporting a light sensitive medium at a speed having a selected relationship to said prescribed speed; and

optical means for focusing the light passing through the slit on said light sensitive medium.

22. A flow camera for reproducing an image on a sheet or document such as a large engineering drawing, map, or architectural plan while the sheet is in motion, said camera comprising:

a frame presenting a slit through which light from the sheet can pass;

first and second sets of entry belts;

means for mounting said entry belts on the frame in a manner to situate opposing belts in the respective first and second sets in opposition to one another for conveying the sheet along a preselected path carrying the sheet in proximity to said slit, with said entry belts terminating at a location upstream from said slit;

first and second sets of discharge belts;

means for mounting said discharge belts on the frame in a manner to situate opposing discharge belts in the respective first and second sets thereof in opposition to one another for conveying the sheet away from the slit along said preselected path, with said discharge belts spaced downstream from said slit and from said entry belts to present a gap between the entry and discharge belts at a location adjacent to said slit;

means for driving said entry and discharge belts to effect conveyance of the sheet along said preselected path at a prescribed speed;

means for supporting the sheet in a planar form in said gap;

means for lighting the sheet in a manner to direct the light through said slit;

means for transporting a light sensitive medium at a speed having a selected relationship to said prescribed speed; and

optical means for focusing the light passing through said slit on said light sensitive medium.

23. A flow camera as set forth in claim 22, wherein said supporting means comprises a pair of transparent plates on the frame spaced apart from one another adjacent to said gap and arranged to receive the sheet between said plates for support of the sheet in said gap.

24. A flow camera as set forth in claim 23, wherein said lighting means comprises:

front lighting means for applying light to a side of the sheet facing said slit for reflection of the light from said front lighting means off of the sheet and through said slit;

back lighting means situated such that the sheet is between said slit and back lighting means to effect transmission of light from said back lighting means through the sheet and then through said slit;

25. A flow camera for reproducing an image on a sheet or document such as a large engineering drawing, map, or architectural plan while the sheet is in motion, said camera comprising:

a frame presenting a slit through which light from the sheet can pass;

means for conveying the sheet at a prescribed speed along a conveyor path carrying the sheet in proximity to said slit;

means for lighting the sheet in a manner to direct the light through said slit;

a light tight optical tower on the frame at a location to receive the light passing through said slit;

a mirror;

means in said tower for providing a guideway into which said mirror can be inserted and held in a fixed position in the path of the light entering the tower through said slit, said mirror being selectively removable from said guideway and from said tower;

a film compartment on said frame;

means in said film compartment for receiving a light sensitive medium and transporting said medium at a speed having a selected relationship to said prescribed speed; and

lens means for focusing the light reflected from said mirror onto said light sensitive medium.

26. A method of reproducing an image borne on a sheet or document such as a large engineering drawing, map, or architectural plan at a preselected size reduction, said method comprising the steps of:

conveying the sheet at a prescribed speed with the sheet held flat and traveling in a direction perpendicular to a transverse dimension of the sheet;

reflecting light from a front face of the sheet while the sheet is traveling at said prescribed speed;

projecting light through the sheet from a side opposite said front face;

focusing at an exposure station the light which reflects from the sheet and the light which is projected through the sheet; and

transporting a light sensitive medium past said exposure station at a speed which has a correlation to said prescribed speed determined by said preselected size reduction.

27. The method of claim 26, wherein the light which is reflected from the sheet and projected through the sheet is directed through a slit having a length dimension oriented parallel to the transverse dimension of the sheet.

28. The method of claim 27, including the step of reflecting the light off of a single mirror prior to said focusing step.

29. The method of claim 28, wherein the light reflects off of said mirror at an angle less than 90°

.