GB1070605A - Method and apparatus for electrostatically adding additional elements to drawings - Google Patents

Abstract

1,070,605. Printing. WESTERN ELECTRIC CO. Inc. Oct. 22, 1965, No.44774/65. Heading B6C. [Also in Division G2] Details, such as notes, tables, which are common to a number of drawings, are added to a drawing by preparing an unfixed electrostatic powder negative image of the details on a transparent sheet, transferring the image to the drawing by corona discharge means, removing the transparent sheet, and fixing the powder image on the drawing by applying a vaporized liquid which condenses. The drawing is first placed on the light-transmitting and electrically conducting base 46 of a drawer 42 which is then moved into a cabinet 30. A carriage 60, which is movable by a motor and reversing screw from the rear of the cabinet to the front and back again when a button 140 is operated, carries corona generating wires (70, Fig. 4), screen wires (72), and a vapour discharge tank 75. The wires (70, 72) are connected to brushes (66, Fig. 3), running on high-voltage supply rails 56. The tank 75 is connected by flexible piping 92 to a fixed supply tank 88 and has on its underface two sets of staggered nozzles (116), one set extending from the centre towards one of the sides and the other set extending from the centre towards the other side. Valves 80, 82 control the admission of liquid to the two sets of nozzles and can be actuated so that either or both valves can be open. By actuation of a selector knob 176, it is arranged that the corona wires (70, 72) apply a charge to the drawing during a first to-and-fro movement of the carriage 60, the vapour-applying apparatus being inoperative. The drawer 42 is now pulled out and the transparent sheet is placed on the drawing in the required position with the powder image downwards. Another reciprocatory movement is now initiated by depressing the button 140 and the corona discharge causes the transfer of the image to the drawing. The drawer 42 is then withdrawn again and the transparent sheet is removed. The selector knob 176 is now set for operation of the vapour applying apparatus, and the button 140 is subsequently depressed to cause another reciprocatory movement of the carriage 60. During such movement, either or both of the valves 80, 82 are opened according to the setting of a knob 160, so that vapour issues from the nozzles (116) on to the whole or parts of the drawing, and condenses to fix the image. Heaters (118, Fig. 4), in the vapour discharge tank 75, connected by brushes 67 to supply rails 57, assist in vaporizing the liquid and are in circuit with a thermostat 120. Another thermostat 138 mounted on the tank 75 is connected, through a brush and rail (68, 58, Fig. 3), in the circuit of the motor reciprocating the carriage, so that the motor cannot be started unless the tank has reached its operative temperature. The circuitry is arranged so that the corona. discharge devices and. the vapour applying devices cannot be operative at the same time. The polarity of the corona discharge can be set by a switch-controlling knob 178 according to the polarity, of the powder image on the transparent sheet.