High speed imaging of electrophotographic film by fine beam scanning

Apparatus for high speed imaging of an electrophotographic material comprising:

• A. means for scanning a master image with a reading beam of energy that can be modulated in accordance with said optical variations of the master image and in accordance with a predetermined scanning pattern,
• B. means for converting the modulations into a stream of electric signals,
• C. store means for receiving said stream of electrical signals,
• D. means for converting the stream of electric signals from said store means into a fine writing beam of radiant energy with modulations related to the modulations of the reading beam,
• E. means mounting a member of electrophotographic material in darkness comprising a photoconductive coating capable of accepting and discharging a charge of high speed and formed of a thin film, transparent, microcrystalline, electrically and optically anistropic, high quantum gain, wholly inorganic material,
• F. means for charging of a limited region of the coating of the member in darkness progressively at high speed to a surface charge potential capable of being fully discharged by said writing beam in accordance with the modulations thereof,
• G. means for directing the writing beam successively to impact onto the charged limited region of the coating in darkness progressively immediately subsequent to charging of said limited region substantially fully to discharge said limited region,
• H. means for effecting relative movement between the mounting means and directing means at high speed to cause the writing beam substantially to reproduce the said predetermined scanning pattern whereby to reproduce an overall latent charge image formed of regular geometric shapes consisting of an array of charged limited regions of said surface and substantially fully discharged limited regions of said surface, each fully discharged limited region being respectively equal to the area of each impact area of the fine beam with the remaining charged limited regions of the surface having the same dark decay rate so that substantially all the charged remaining limited regions within the overall latent charged image are capable of retaining their charge value subject only to dark decay rate, the charged and discharged limited regions being distributed in an array reproducing said predetermined scanning pattern representative of said master image, and
• I. means for developing said overall latent image subsequent to complete formation thereof said directing means comprising a movable carriage having a beam deflector for pointing the writing beam directly to the photoconductive coating from a point on said carriage, said charging means including a corona producing device mounted on said carriage spaced from said point in a direction which will bring the corona producing device progressively into proximity with each portion of the photoconductive coating before the writing beam engages the same, but at the same scanning rate, said mounting means holding said electrophotographic member in a cylindrical configuration, the photoconductive coating of the member is on the inside of the cylindrical configuration, said carriage being arranged to move along a line coaxially of said electrophotographic member along the length thereof with simultaneous relative rotational movement of the carriage and electrophotographic member and the carriage is rotatable on the axis defined by said line.

In an apparatus for high speed imaging of an electrophotographic material in which there is a source of data that is in binary form and which represents the information capable of being developed into a master image, a radiant energy device having a fine beam of discrete bursts of energy derived from the source and capable of producing the master image if used to write the fine beam upon a suitable responsive medium, the invention herein which comprises means for effecting such production and including:

• A. an electrophotographic member including a photoconductive coating capable of accepting and discharging a charge at high speed,
• B. means for charging a limited region of the coating of the member in darkness progressively at high speed to a surface potential capable of being adapted substantially fully discharged by said fine beam,
• C. means adapted to receive said beam and direct the same onto the charged limited region of said photoconductive coating in darkness progressively at high speed,
• D. means mounting the electrophotographic member in darkness,
• E. means for effecting relative movement at high speed between the mounting means and the directing means in a form of movement adapted to cause any said beam received to engage against and scan the coating for substantially fully discharging only selected limited regions of impact of said fine beam in accordance with the master image, the remaining charged limited regions discharging in darkness in accord with the same dark decay rate for producing an overall latent image of said master image, and
• F. means for developing the overall latent image formed.