GB1430047A - Printer apparatus - Google Patents

Abstract

1430047 Automatic electric control of position INTERNATIONAL BUSINESS MACHINES CORP 16 May 1974 [26 June 1973] 21723/74 Heading G3N Printing apparatus includes means for feeding forms to a print station and a control means responsive to a detector of the leading edge of the form and to the motion of the form to align a predetermined line on the form with the print station. In the constructional arrangement shown in Fig. 1 the form 10 is advanced by a pin tractor feed mechanism including belts 15 and 16 driven by motor 22 past the print mechanism 12. A sensor 30 detects optically the leading edge of the form and a sensor 32 detects the passage of the form by an optical arrangement co-operating with the feed holes in the form. The motion of the form can also be detected by the transducer arrangement 27, 28 which is used to give positions intermediate those provided by the feed holes sensor. Effectively the control circuit shown in Fig. 2 includes a counter which is incremented by the motion of the form until a pre-set count is reached which count corresponds to the distance D + d when a print enable signal is generated and the normal print control takes over. In operation the switch 49 is closed to start the motor 22 and the thread latch operates to remove the reset signal from align counter 34 but this does not count pulses from sensor transducer 33 until it is enabled by the leading edge sensor 31. The pulses from sensor 33 are also applied to the reset terminal of jam counter 41. A manually pre-set code corresponding to the number of pulses representing distance D + d is stored in register 39 and the count in counter 34 is compared with this figure in comparator 38 until equality is obtained when a print enable signal is generated and control is taken over by the CPU. The thread latch is reset and this holds the align counter reset during further feeding of forms. If there is no form present e.g. because of a jam then the output from transducer 28 will increment jam counter 41 until a pre-set value is reached when a stop and reset signal is generated. In an alternative arrangement Figs. 5 and 6 (not shown) the pulse output from the transducer 28 can be used in align counter 34 for positioning the form. The passage sensor 32 may be spaced a longer distance from the form edge sensor and used to give automatic starting of the printer when a form is inserted. In this case a delay is needed in the jam counter circuit, Figs. 3 and 4 (not shown).