GB1421474A - Printer control system - Google Patents

Abstract

1421474 Control of printers INTERNATIONAL BUSINESS MACHINES CORP 15 Nov 1973 [26 Dec 1972] 53050/73 Heading G4H A printer incorporates means for varying the width of the pulse applied to the print hammers in accordance with the thickness of the forms on which printing is effected and with the print hammer energization voltage so as to maintain a constant impact force to provide uniform print density. Means are also included for varying the time of initiating the pulses. As described, the printer 11, Fig. 1, is the belt printer of Specification 919,653. Data from buffer 26 is scanned under the control of a gating ring 34 defining subcycles in which groups of hammers 20 are energized by latches 36. In the present invention, the outputs from latches 36 are fed via gates 38 enabled for variable times by a pulse control 40, Fig. 4, connected to ring 34, to the voltage source, to a potentiometer 42 whose setting is controlled by the sensed forms thickness (up to 6 forms may be used), and to a device 18 which monitors the movement of belt 12. A pulse from 18 sets a latch 44 which causes the sequential actuation of delays 46, 48 whose durations are non-linear functions of the 24 V supply and the setting of potentiometer 42 respectively At the end of these delays, output 94 from 48 resets latch 44 and provides one input to gates 50-54 one of which is selected by the scanning circuitry. The output from the enabled gate sets a latch 56-60 which starts a delay 62-66 whose duration determines the width of the pulse applied to the print hammers, this width being a non-linear function of the supply voltage and the forms thickness as determined by a control 68. At the end of the delay, the corresponding latch is reset, and the print hammer pulse is terminated. Circuit embodiments are described (Figs. 5- 10, not shown) for the various blocks of Fig. 4.