Details:
Summary:
Electrostatic printing has previously made use of photoconductive materials for the generation of electrostatic images. Development of these images by dusting techniques and their subsequent transfer from the photoconductive surface to paper results in permanent copy. The videograph process, on the other hand, produces an electrostatic image directly on the surface of the paper. The image is created by use of an electrostatic printing tube. This tube is similar to a conventional cathode ray tub with a matrix of conductors imbedded in the glass of the faceplate. Beam current impinging upon the inner ends of these wires causes a charge to be transferred through the faceplate of the printing tube to the paper surface. Control of the position and intensity of the electron beam creates the desired electrostatic image. The resultant image may then be electrostatically developed as in earlier processes and fixed to form a permanent copy. The system functions in accordance with video information. The video signal may be derived from flying spot scanners, from vidicon cameras and from digital data acted upon by the Monoscope Character Generator. The videograph process combines low supplies cost with high operating speeds. Previous electrographic recording techniques have lowered the supplies cost but have not attained speeds capable of volume production. For high volume printing applications the supplies cost dominates in determining the cost per sheet of output copies. Other forms of high volume printing require use of masters that increase the cost of supplies. This must be added to the basic paper and labor costs and is a function of the number of copies per master. The Videograph, by eliminating the master and by its operating speed, proposes to become an economic production machine in the future for many reproduction applications.