Patent GB-789549-A (GB)
Title: Improvements in or relating to photographic type composition
Inventor: HOOVEN FREDERICK JOHNSON
IPC: B41B17/10
Filed: 1955-08-04
Abstract: 789,549. Digital electric calculating apparatus. HARRIS-SEYBOLD CO. Aug. 4, 1955, No. 22433/55. Class 106 (1). [Also in Group XX] A photographic type composing machine (see Group XX) having a character carrier rotating continuously with respect to a flash source of light includes means for continuously advancing the film in direct relation with the rotation of the carrier and in increments which are small in relation to the individual character widths, means for selecting a series of characters, means .controlled in accordance with the character selected for controlling the instant of flashing of the light source within a single revolution of the character carrier to effect the exposure of a selected character on the film, means for sensing the width of the selected characters, and means controlled in accordance with the width sensing means for causing the rotating system to rotate a number of whole revolutions to advance the film proportionately in accordance with the width of the selected characters to effect the proper number of increments of film advance to accomplish the spacing of the character in the line. General description.-The keyboard of the machine is similar to that of a typewriter and a typed copy appears in front of the operator. Alternatively the keyboard or its equivalent may be actuated automatically from a record such as a tape or wire. Upon actuation of the keyboard, pulse data for character selection and spacing are magnetically recorded on discs or cylinders mounted on the same shaft as the character drum. When the line recorded has been checked for accuracy, a " Print " key is operated to initiate the printing cycle. The character drum rotates continuously past a gas discharge tube or spark gap which produces a bright brief flash of light so as to form an image of the selected character on the photographic film without blurring. The drum is geared to the film carriage, and after a character is recorded, rotates through several revolutions to allow the carriage to move through a distance sufficient for the spacing of the characters before another exposure is effected. The spacing is thus a whole number of units, each unit being equal to the distance through which the film carriage moves in one revolution of the drum; this distance may be varied in accordance with the point size of the type. When interword spaces occur, the drum makes several revolutions without any printing operation. Calculating apparatus is provided for dividing the line shortage between the interword spaces to justify the line. The control signals are all of pulse form and control the machine through various electronic circuits, such as amplifiers, gate circuits (which have two inputs and transmit a pulse only when pulses are fed to both inputs), buffer circuits (which transmit pulses fed to either of two inputs), electronic switches, &c., which are of known kinds and of which typical examples are described. Counter.-The electric binary counter shown in Fig. 11 has a number of stages, each consist - ing of a double triode V11, V12 ... Vn connected in a " flip-flop " circuit. The input, consisting of negative pulses to be counted, is applied to the cathode of a double diode V20, which is held at a potential about equal to that of the more positive of the anodes of V11. A negative pulse is thus applied only to the more positive anode of V11 and causes the circuit to shift to its other stable state. Alternate input pulses cause negative pulses to be passed from V11, through a double diode V21 connected similarly to the double diode V20, to the second stage V12, and so on. If the stable states of each stage are represented by 1 and zero respectively, the states of the stages after each successive pulse represent the number of pulses counted, expressed in binary notation. If the stages are originally all in the state represented by zero, then after the last pulse before the capacity of the counter is reached they will all be in the state represented by 1. The next pulse causes V11 to change from 1 to zero, and to emit a pulse which causes V12 to change from 1 to zero, and so on until Vn also changes from 1 to zero. This causes a negative pulse to appear at the anode Pn of Vn, which is fed through a combined amplifier and cathode follower V22 to an output connection. At the same time, a positive pulse appears at the other anode P2n of V22 and triggers a gas discharge tube V23. A negative pulse appearing at the anode of V23 passes through a condenser to a line 50, which is connected by switches 51, 52 ... 50n to the counter stages in such a way that when one of the switches is closed, the corresponding stage shifts from zero to 1. Thus the pulse from V23 re-sets the counter to any number required within its capacity which is selected by closing a combination of the switches 51, 52 ... 50n. The initial state of the counter may be definitely determined by a switch 60, by which alternate connections in the " flip-flop " circuits are connected a source of negative potential. When switch 60 opens momentarily, all stages assume the 1 position. When the switch closes again, a negative pulse is applied to the first stage and the stages successively shift to the zero position, emitting negative pulses as described so that the counter is pre-set to the number determined by the combination of the switches 51, 52 ... 50n which have been closed. Fig. 12 shows a fourstage binary counter which may operate either to add or subtract the pulses fed in. The four stages, comprising double triodes V31, V32, V33, V34 connected as " flip-flop " circuits, are connected by means of pentagrid valves V35, V36 ... V40. Each of the pentagrid valves has two control grids, e.g. grids G361 and G363 in valve V36, grid G361 is maintained at such a negative bias, and is so coupled to the anode p312 of valve V31 that it tends to cause current to flow in the valve V36 whenever anode p311 shifts to a more positive state, i.e. when the counter state shifts from zero to 1. Similarly, current will tend to flow in valve V35 when valve V31 shifts from 1 to zero. When current flows in the anode circuit of either of valves V36 or V35 it flows at a pulse through coil L10. Since coil L10 is in the anode circuit of the stage V32, the pulse will cause a shift of the stage V32. When the third grid of valve V36, V38 and V40 are rendered negative so as to render the valve inoperable, the counter will perform the operation of addition. When the valves V35, V37 and V39 are rendered inoperable by a negative bias of their third grids, a counter will perform the operation of subtraction. The choice of operation is governed by a " flip-flop " stage V41. Pulses may be applied to this stage through either of two inputs 13, 14, and the state of the circuit V41 determines which of the two sets of coupling pentagrids is operative. A valve V43 is connected to valve V41 in an electronic switch circuit, such that pulses appearing at the input circuit 11 of the counter will be counted when the tube V43 is in the closed state, and added to the count recorded by the counter. Pulses appearing at the input circuit 12 will be counted into the counter whether the switch V43 is opened or closed. A valve V42 is connected as a cathode follower and rectifier so as to produce a negative output pulse whenever the last stage V34 of the counter shifts from zero to 1. Recording carriage escapement.-The carriage and keyboard are similar to an ordinary typewriter, but the carriage is connected by a tape passing round the drum to a shaft, which in turn drives, through a tape and drum, a recording head and an erasing head. The heads pass along the surface of a cylinder surfaced with magnetic recording material with the erasing head leading. The shaft is spring driven and controlled by a pawl-and-ratchet escapement, operated electrically whenever a key is actuated. The shaft operates a recording sequence selector comprising an arm fixed to the shaft and sweeping over a set of contacts. The carriage is returnable automatically or manually by known means. Recording of characters.-In the machine exemplified in Fig. 17, it is assumed in order to simplify the description that there are only twelve characters. As shown, a number of magnetic discs are mounted on the same shaft 145 as the character disc 150. Three of the discs have one or more signals permanently recorded thereon to generate pulses in one or more fixed pick-up heads. These discs comprise: (1) the space pulse generator SPG, having a number of pulses equal to the maximum character width in elementary width units recorded at each character angle, and a pick-up head 350; (2) the timing pulse generator TPG, having a narrow pulse recorded at the beginning of each character angle, and a pick-up head 315; and (3) a key pulse generator KPG having a single broad pulse recorded thereon and a series of pick-up heads, such as 306, one at each character angle position. The three recording discs comprise: (1) the recording space register RSR having a recording head 360 at the datum position, a pick-up head 420 as an arbitrary angle and an erasing head 439 opposite the recording head; (2) the printing space register PSR having a recording head 430 and a pick-up head 470; and (3) a word space register WSM having a recording head 406 and a pick-up head 520. A magnetic cylinder, the character memory cylinder CMC, is mounted on shaft 145 between the generating discs and the recording discs. A recording head 320 and a pick-up head 440 moves stepwise along opposite sides of the cylinder. Finally, the character space pulse generator CSPG comprises a magnetic disc associated with the character drum 150 and carrying at each character angle a number of pulses equal to the width of the corresponding character in elementary width units. Each key on the keyboard has a switch 300 which is closed when the key is depressed. Further, every time a