GB995816A - Improvements in or relating to electrostatic image copier - Google Patents

Abstract

995,816. Electrostatic image copying employing scanning. DICK CO. A.B. Jan. 1, 1964 [April 1, 1963], No. 88/64. Heading H4F. In an electrostatic image copier employing scanning a charge pattern corresponding to a line of the image is laid down by a line array of electrodes 36A, 36B, 36C &c., Fig. 2, which are retained in holes in an insulator 34 and each of which is associated with a photo-conductive (e.g. cadmium sulphide) element 38A, 38B, 38C &c. which connects the electrode with a translucent conductive layer 40. A video signal representative of an original image to be copied is derived through an amplifier 30 from a photo-electric cell 24 which scans the image and is applied to layer 40, whilst the photo-conductive elements are rendered conductive in succession by light from a constant source which is scanned along the array of elements in synchronism with scanning of the image. A source of radio-frequency oscillation is applied to a backing electrode 26B and the medium, e.g. paper, on which the record is to be made is traversed in the gap between electrodes 26B and the array of electrodes 36. In one apparatus, Fig. 3, the original image 10 remains stationary and is located adjacent a constant light source 50. The image is scanned in a succession of vertical lines by a rotating mirror assembly 52 which co-operates with a photoelectric cell 54 traversed horizontally by a lead screw 56. At the same time mirrors assembly 52 also scans the light from source 50 over the array of photo-conductive elements in the electrostatic copier 62 so that they are rendered conductive in succession in synchronism with the scanning of each line of the original image. In another apparatus, Fig. 2 (not shown), the original image is carried by a drum which is rotated to introduce one component of scan. The recorded electrostatic image is rendered visible by known processing methods. The image scanning photo-electric cell may have a desired spectral response and the desired video signal may be processed in suitable circuits to obtain a desired signal amplitude, polarity and linearity.