Patent GB-1237428-A (GB)
Title: Printer apparatus
IPC: G06K15/08
Filed: 1968-11-06
Abstract: 1,237,428. Selective printing. RCA CORPORATION. 6 Nov., 1968 [7 Nov., 1967], No. 52533/68. Heading B6F. [Also in Divisions G4-G6] In a printer of the kind in which a printing member moves along a printing line forming characters at spaced positions under the control of input signals, means are provided after an interruption in the input signals to cause the member to proceed to and stop at a position clear of the last printed character (so that it can be seen) and to be returned for resumption of printing at the next printing position when the input signals are again supplied. The printing member is an anvil which moves along parallel guides under the control of a cable passing round a pulley at each end. One pulley is driven by a motor, the other carries a coded disc photoelectrically sensed to provide signals indicating the position of the anvil. The paper is of the sort on which an impression is made by pressure. Copy sheets with carbon paper are positioned behind this. The character shapes are formed by a series of bars, each of which is controlled by a solenoid to move towards the anvil to make an impression. The bars are arranged in a stack, one above the other and they move into and out of the printing position as the anvil moves along the printing line. The input signals are applied at 26 and temporarily stored in buffer 31 before passing to a selection register 33. The output of register 33 passes to a character generator 35 which produces a group of signals for application to the driving circuits 37 of the printing bar solenoids 22. A clock pulse generator 54 produces pulses for each character or space from the beginning of the line. These pulses are counted in a counter 42 which starts with a count of one so that it registers the position of next character position to be printed. The output of counter 42 is compared at 40 with the anvil position signal provided by the coded disc. The output 43 is applied to the anvil drive control 46 driving the motor 4 backwards or forwards by signals on leads 50a, 50b. The control 46 is also controlled by signals on leads 51a, 51b from the register 33. The control 46 also applies control signals to the bar driver circuits 37 and a gate 53 which also receives the output 43 of the comparator. The gate 53 supplies a reset pulse to the clock 54 and the register 33. The clock provides two sets of clock pulses, a first set on lead 56 to the character generator and a second set to the counter 42. While there are signals in the register, the anvil is continuously drawn across the printing line each character being printed in a cycle beginning with the resetting of clock 54 and register 33 which then receives the next character position the comparator produces an output which passes to the control 46 to produce a stroke signal on line 52. The signals from register 33 pass to the character generator energizing the bar solenoids in the proper sequence to form the character. When there is no longer any signals in the register 33 the control 46 responds by removing the signal on lead 52 so that the bar drivers are not operated and after a set delay the forward drive signal on line 50G is terminated. The delay is sufficient to allow the anvil to move several spaces past the last printed character. When new signals appear in register 33 the signals on leads 51G and 51a cause the anvil control to drive the anvil backwards to a position to the left of the last printed character. The anvil is then driven forward again. When the comparator indicates that the anvil is in the position of the next character to be printed the signal on lead 52 enables the driver 37 to resume printing.