Patent GB-980077-A (GB)
Title: Improved means for setting the type wheels of printing apparatus
Inventor: TRUMAN JEFFREY ARTHUR
IPC: B41J7/48
Filed: 1960-07-28
Abstract: 980,077. Selective printing. W. & T. AVERY Ltd. July 17, 1961 [July 28, 1960], No. 26220/60. Heading B6F. [Also in Division G4] Type-wheel machines; type-wheel actions.- A weight record printing apparatus comprises at least one type-wheel 20 mounted loosely on an oscillating shaft 21 for angular movement therewith, a solenoid 23 actuated pawl 27 for arresting the type-wheel whilst permitting the shaft to continue its movement and wipers 31 with a code pattern 29 for comparing an electric input signal with the position of the type-wheel so as to operate the solenoid-actuated pawl when the angular position of the type on the wheel coincides with a given input signal. In the apparatus the shaft 21 (Fig. 1) connected to driving means (not shown), for oscillation through an angle at least equal to the angular range of type characters on the wheel's periphery, carries a fixed collar 22 having a pin 23 projecting axially through an arcuate slot 24 in the wheel 20 and which in conjunction with a spiral spring 25 connected to a pin 23 and a pin 26 on the wheel spring loads the wheel in a clockwise direction to thereby normally locate the pin 23 at the anti-clockwise end of the slot 24. When the shaft is oscillated in a clockwise direction the type-wheel moves with the shaft and a coded pattern 29 of binary form (Fig. 2) is scanned by a bank of wipers 31, which when they detect a conducting pattern corresponding to an input signal fed to them for decoding and printing, feed a signal to the solenoid 28 whereby the pawl 27 engages the toothed arc wheel and arrests the wheel, whilst the shaft continues its movement against the resistance of the spring 25, whereupon printing takes place preferably at the end of the stroke of the shaft and the solenoid is de-energized to release the wheel which is reset in its start position so as to respond to the next coded input to the input bank. In another embodiment (not shown) the wipers may be mounted on the drum for angular movement so as to scan a stationary code pattern. In a further embodiment when a multi-digit record is to be printed a plurality of type-wheels may be mounted on a common oscillating shaft and each operated by a separate bank of wipers and a solenoid-operated pawl. Selective electric signalling.-The control circuit for setting of the mechanism for selection and printing of numerals 0 to 15 consists of a four-stage binary counter 32, 33, 34, 35 (Fig. 3) having two binary states " 0 " and " 1 " corresponding to a supply of 0 and- V volts, respectively. Each output from the counter is fed through two equal resistors R to a wiper 31, with the code pattern 29 connected to a + V volts supply, with junctions A, B, C, D of the series resistors connected via a diode rectifier 36 to a common line 37, connected to a supply of + V volts via a comparatively high resistance S and to the locking pawl solenoid 28 via an amplifier 38, so that when the line voltage is zero the amplifier conducts and operates the solenoid. Electrical interlocks (not shown) are provided to prevent printing if there remains excessive positive or negative supply on any of the solenoid supply lines indicating incorrect location. Type-wheel construction.-The type-wheel of low inertia takes the form of a drum whose surface is divided into three equal sectors viz. a type arc including sixteen equally spaced characters (not shown) for printing of one of selected numbers 0-15, a toothed arc incorporating 15 ratchet teeth cut at a similar pitch to that of the type characters and a third sector incorporating a binary case pattern 29 constructed by engraving away unwanted areas of the conductive material constituting the drum periphery and flush filling these areas with a non-conductor, in a similar manner to a commutator, leaving inter-connected conductive areas 30, scanned by a bank of four wipers.