Flow camera for large document reproductions

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.

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.

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.

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.

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.

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.