Patent GB-1240296-A (GB)
Title: Printer document carriage control
IPC: B41J11/42
Filed: 1968-07-22
Abstract: 1,240,296. Print format control. INTERNATIONAL BUSINESS MACHINES CORP. 22 July, 1968 [21 Aug., 1967 (2)], No. 34871/68. Heading G4H. Print format is controlled by an apparatus which includes a store containing at each addressable storage position coded representations of a line to be printed, a register for holding single command signals, a comparator for comparing successively addressed representations from the store with the register contents to produce a compare signal, a counter which is incremented each time the store is addressed and stopped by the compare signal, a pulse generator for driving the print carriage, and a device responsive to a predetermined count in the counter for causing the pulse generator to stop the carriage movement. In operation; skip to line " m " commands.- As described a register 78 is used to store the command signal and a further register 83 is used to hold the representation being written into or read out from the main store 40 The compare unit 77 stops and complements the line counter 150 which is incremented by the clock and controls 60-66 used to address the store 40 when the representation withdrawn from the store 40 matches the command in register 78, i.e. when the line to which the skip is to be made has been located. The pulse generator is a slotted disc 111 driven by the carriage advance motor 22 which is activated when read-out from the store 40 commences but does not move appreciably before the line counter 150 has been stopped and complemented. The carriage control counter 130 counts the pulses from the generator 111 and increments the line counter 150. The counter 150 is set to zero or 2 according to whether 6 or 8 lines to the inch are being used, the counter emitting a pulse every sixth or eighth pulse to increment the counter 150. It will be appreciated that the number of pulses required to fill the counter 150 after it has been complemented is equal to the number of lines which have to be skipped. When counter 150 is full it emits a pulse which, by means of gates 110, blocks the pulses from the emitter 111 and stops the carriage motion. Skip more than fifteen lines.-The capacity of the counter in the embodiment is 15 so that when commands to skip more than 15 lines are received the store must continue to be addressed after the counter 150 has been filled. The counter is held at a count of 15 and the addressing operation continues driven by the pulses from the counter 130. For example, if the skip is to be 20 lines the address withdrawn from the store 40 when the counter 150 became full will be 16, assuming that line 1 was in the print position at the start of the operation. The next four addresses will be withdrawn from the store 40 as the carriage is advanced four lines, and a compare signal will then be produced. The contents of the counter 150 (i.e. 15) will be complemented (i.e. to zero) and the operation proceeds as before, pulses for the counter 130 being passed to the counter 150. Space "n" lines.-For commands of this type the counter 150 is set to a particular count directly from the command register 78, a latch in the register being used to prevent addressing of the store 40. For example if the command is to space one line a count of 14 will be set in the counter 150, and the stepper motor will be started causing the counter 130 to advance. After 6 or 8 pulses according to the line spacing required the counter 150 will be incremented to its maximum count of 15 and the motion stopped. Further details.-The embodiment is described in some detail and gating arrangements are described which allow the speed of the carriage movement to be related to the distance it has to move. The store 40 and the register 78 may be connected directly to a computer or may be loaded manually.