Patent GB-915323-A (GB)
Title: Improvements in or relating to typewriters
IPC: G06F11/10
Filed: 1959-04-05
Abstract: 915,323. Typewriters; strip perforating. INTERNATIONAL BUSINESS MACHINES CORPORATION. April 5, 1960 [April 9, 1959], No. 11958/60. Classes 100 (3) and 100 (4). Typewriting and producing simultaneously a magnetic data tape.-A type-lever typewriter in which simultaneously with printing, a record is made in a magnetic tape 22, Fig. 3, comprises a magnetic head 21 reciprocated across the tape by a helix 35 coupled to a drive 25, 30 by a clutch 32 operated upon actuation of a type-bar mechanism 2, 4, 9, 12, Fig. 1, the head 21 being pulsed during the reciprocation to record marks in the tape. All codes entered in the magnetic tape comprise an odd number of marks and during the return of the head 21 to its starting position the head reads the marks which have been made. If a number of marks sensed is " even " then the keyboard is locked by the release of an electromagnet 99 against further operation. Correction is made by back-spacing and although a backspacing code is entered in the tape it is automatically erased during the entry of further data. The actuation of a key 1, Fig. 1, operates a power-roller mechanism, and particular contacts 12 and common contacts 14 are operated. Contacts 12 operate an encoding circuit, comprising relays R3 to R10, Fig. 5b, whose contacts close circuits to a series of emitters 61-1 to 61-8, Fig. 5c. These emitters are mounted in a helical path on a stator 60 surrounding a drum 58 mounted on a shaft 23 driven by the onerevolution clutch 32 when the contacts 14 are closed. On the drum 58 are a series of magnetic slugs 59 which are on a different helix to the emitters and when the slugs pass an emitter to which a through connection is made by the relay contacts R3a to R10a a voltage pulse is generated; is amplified at 82; passes through the relay contacts, line 84, voltage amplifier 85; a single shot device 88 which applies a single shot pulse for each input pulse, and finally through a cathode follower 89 to the relay winding 90 on the head 21. Data is thus entered in the tape at different times as the head 21 moves across the tape 22. Erasing and back-spacing; letter-spacing.- The machine will automatically erase wronglyentered data, upon back-spacing the typewriter, but when the typewriter is being operated in response to data in the tape and ordinary backspacing is required, e.g. to underline typing, a back-space code is recorded in the tape. The head 21 comprises two coils, a read-write coil and an erasure coil wound round poles 106, 107, Fig. 10. When an error has been made the winding on the pole 107 is in advance of the " write " pole 106, so that during the next reciprocation of the head 21 the erroneous data is erased and the re-entered data is inserted by the following narrower pole 107. When the head 21 returns to the left a tape-feeding drum 40 is advanced by a ratchet-and-pawl mechanism 43-49 and a cam 51. The operation of a back-spacing key effects closure of contacts and clutch 32 and a magnet 57 operates to shift the pole mechanism 43 to 49 so that it engages the reversed side of a mechanism to step the tape backwards. At the same time a code mark is entered in the character position in which the error was detected but is erased by the next entry. If a back-spacing code is required for reading by the typewriter the tape is not backspaced. A manual switch enables this to be done so that the added matter can be recorded in the tape which is stepped ahead accordingly. Strip-controlled typewriters.-A manual switch is moved to a " read " position when the typewriter is to operate from the record. In this position all the keys of the keyboard are locked by the magnet 99. Further the erased winding on the head 21 is de-energized so that no information is erased as the head is moved across the tape. The " read/write " head is connected by relays to a read amplifier 92, a single-shot device 88, cathode follower 89 to one grid in each of thyratrons 123-1 to 123-8 which are thus all applied with a pulse. The second grids are connected to the emitters 61-1 to 61-8 so that when a mark is sensed that thyratron is conductive and sets one of a bank of relays R14-R22. The contacts of these relays are connected to a decoding matrix arranged in two pyramids, the peak of one being the inverse of the other, which reduces substantially the number of contacts required by any one relay. These operate either the type-bar magnet 16 or a function key magnet which draw the type lever actuation cam to the power roller without operating the corresponding key. If during the reading of the tape any character position, an " even " number of marks is sensed, a circuit will be completed through the relay contacts to effect energization of the thyratron 95, operate the error relay and stop the machine. Specifications 655,492 and 743,618 are referred to.