GB1441563A - Timing signal generating system for a printer - Google Patents

Abstract

1441563 Printers DATAPRODUCTS CORP 17 Jan 1975 [17 Jan 1974] 2214/75 Heading G4H A system for generating timing signals for hammer actuation in a printer comprises sensing means 35 adapted to sense the passage of characters along a printing line along which the hammers are aligned more closely spaced than the characters), a phase detector 36 comparing the phases of the output of the sensing means 35 and an output of a ring counter 42 to control the frequency of a voltage-controlled oscillator 40 via filter-integrating means 41, the oscillator 40 driving the ring counter 42. As disclosed, the ratio character spacing (on a typebelt moving along the print line) over hammer spacing is 5/4 so the ring counter 42 has 5 outputs corresponding to the 5 sub-cycles in which respective interleaved groups of characters become aligned with hammers, to control hammer actuation timing. The oscillator 40 frequency is nominally five times that of the pulses from detector 35 which detects slugs 30 on typebelt 10 (one character per slug). Another detector 75 detects only some slugs (e.g. one) to reset counter 42. Variable delays 48, 86 are for initial adjustment. There may be more than one character per slug in which case a division circuit is inserted in the connection from counter 42 to phase detector 36.