公开(公告)号：DE3279880D1

公开(公告)日：1989-09-14

申请号：DE3279880

申请日：1982-05-13

Applicant: IBM

Inventor： GIORDANO FRANCIS PETER ,  HENSHAW ROBERT JOSEPH

IPC: B41J2/40 ,  H04N1/40

Abstract: An electrostatic gray scale printing system is disclosed having particular utility for producing gray scale images from signals received from a suitable data source such as a computer, telecommunications line, data storage device or the like. A unique, high voltage, pulse generating circuit is provided for producing gray scale voltage pulses between 300 and 600 volts to the individual styluses making up said printing device. The circuit utilizes a low voltage, power supply and a low voltage gray scale intensity signal input to produce the required high voltage printing pulses. The circuit, per se, consists of a high voltage transistor (Q1) having a relatively large inductance (L) connected in its emitter-collector circuit path. Current flows in the transistor Q1 in response to an input voltage applied to the base of the transistor Q1. The collector current is proporational to the value of the input signal V B divided by the emitter resistor R E . When the transistor Q1 is cut off the inductive tank circuit (L, R I ) produces a high voltage output pulse proportional to the original signal V E placed on the transistor base. The width of said output pulse is related to the value of the resistor R, in the inductive tank circuit which also controls the damping of the output pulse. Coded digital gray level signals are applied to digital to analogue converter 14 and the analogue signals are supplied to a multiplexer 17. The multiplexed output signals are selectively gated to a series of operational amplifiers, such as amplifier A1, as control signals. Each amplifier controls a high voltage transistor, such as transistor 01, and gives rise to an appropriate magnitude drive pulse.