| 摘要 |
1488772 Control of printers INTERNATIONAL BUSINESS MACHINES CORP 7 April 1976 [25 Sept 1975] 14017/76 Heading G4H A serial printer comprising a carrier 1 movable along a print line, a type element 2 having a plurality of type characters and movable on the carrier to present selected characters in position for printing at successive print positions of the line and means 10 to impact the selected character, also includes means 21 to move the carrier along the line and past a print position at a speed selected from a plurality of speeds, means 610, Fig. 6, to determine the time required to position the type element on the carrier to present a selected character at the print position, and means to select the speed of the carrier past the print position in response to the determined time. As shown, element 20 is a daisy wheel (it could be a ball, stick or drum) rotated between stationary printing positions (printing could be on-the-fly). Carriage 1 can be given any of four speeds V1-V4, Figs. 4, 7 (not shown), as determined by processor 610 as a function of the required angular rotation of disc 2. Each speed change is associated with a series of numbers N, Fig. 8 (not shown), which are fed via a memory 615 to preset a counter 630 which is counted down to zero to produce a train of stepping pulses 21A for a stepping motor. To shift the carriage one column 6 stepping pulses and hence 6 numbers are required, each accompanied by a direction-indicating bit 21B; they are followed by an "all zeros" number which is detected at 616 and used to enable gates 671A-671D receiving a signal 610V1, 610V2, 610V3 or 610V4 indicating the carrier speed at the print position: an appropriate one of monostables 672A-672D is triggered to provide a variable delay before firing of the hammer drive circuitry 660. Rotation of disc 2 is controlled by means of a step motor 22 and circuitry similar to that described above. In alternative embodiments, the carrier speed may assume any values between two limits, and provision for proportional character spacing may be made. |
