Patent GB-776925-A (GB)
Title: Improvements in or relating to photographic type-composing machines
IPC: B41B27/10
Filed: 1954-03-12
Abstract: 776,925. Photographic type-composing. MERGENTHALER LINOTYPE CO. March 12. 1954 [March 13, 1953]. No. 7270/54. Class 98(1) [Also in Group XL(b)] A photographic type-composing machine., comprising the combination with a keyboard-actuated composing unit for producing a coded tape, of electrical means controlled from the keyboard for recording character width, word space and character identification signals in the coded tape as a line is being keyboarded, a photographic unit, and electrical means responsive to the signals in the coded tape for photographing the composed line on a light sensitive film, is characterized in that the two electrical means include an endless magnetic tape, driving means to advance the tape, intermittently as a line is being composed, a writing head for magnetically recording on the tape the code assignment for each character or space, a reading head for releasing electrically such recorded information, and supplemental driving means whereby the tape is advanced more rapidly and to a sufficient extent to locate the code signal for the first character in the recorded line into decoding relation to the reading head preparatory to the intermittent advance of the tape for the composition of the following line. Keyboard and Coding Mechanism. The machine includes an electric typewriter having a main keyboard A1 (Fig. 6) with character keys a, a space bar a1, and an end-of-line key a2, and an auxiliary keyboard A2 with character keys a3, a quad key a4 and an erase key a5. The typewriter also includes a paper carriage A3 with a platen A4, and type elements A5 ,whereby the text is typed as it is composed. A coding unit B, Fig. 8, is located beneath the keyboard. The rocking levers a6 carrying the keys a are connected to cams a7 supported by forked members A7 in two staggered rows on opposite sides of a long continuously driven rubber-covered roller A6, the members A7 in each row being pivoted on a rod a8 extending right across the typewriter. Each support member A7 accommodates a linkage which, on depression of the key, releases a cam a7 until it has been rotated half a revolution by contact with roller A7. Each cam, when rotated, engages a roller b3 or b4 on a bar B1 or B2, which is thereby caused to slide longitudinally in supports B3. The bars are normally held against adjustable screw stops b1, b2 by springs b. The coding unit B also includes a set of code bars 2 for character identification and a set of code bars 3 for recording character width. Each bar 2 is L-sectioned and is formed with projections 6 and intervening clearance notches 7, and is mounted on a shaft 4. When a key is depressed. and one of the bars B1 or B2 moves, the code bars of which the propjections 6 lie in the path of projection b5 on the bar, are rocked, together with a "universal" bar 2a which is operated by every key by means of a projection b6 on bar B1 or B2. Levers 13 on the shafts 4, whichever way they turn, close switches 14 to send out electric impulses constituting a code for the character selected. The bars 3 are flat and likewise have projections 8 and intervening clearance notches 9, but are supported on lugs 11 on shafts 10 so as to be longitudinally movable in, say, 5 positions by means of cams 17 on a shaft 18 operated by a knob 21, so that the width of a character may be encoded for upper case or lower case, Roman or italic, or small capitals as required, by switches 14 and levers 13 on the shaft 10. Further, code bars 3 are mounted in a tray 16 which may be re-. placed when the point size of the text is altered. Three cams 22 are mounted on a common shaft to operate contacts 23 which complete electrical circuits which complete the code identification of capitals, ligatures &c. when the dial 21 is set in the proper position. When the space bar a1 is depressed. a slide bar B4 (Fig. 6) is moved which has no projections b5, but instead closes an electric switch A8. Similarly when the end-of-line key a2 is depressed, a switch A9 is closed, and depression of quad key a4 and the erase key a5 result in the closing of switches A10, All (not shown), respectively. Line indicator. A drum C1, Fig. 10, is slotted longitudinally to accommodate 25 slides c, and is driven by an electric motor C5 through a slip clutch C6. The slides c are movable endwise by the armature c1 of a ring of 24 electro-magnets C3. The character width signals set up by the code bars 3 are applied to a decoder to energize a selected electromagnet C3. The slide so actuated protrudes from its slot sufficiently to engage a fixed stop c4 after the drum has rotated .by an amount proportional to the width of the character. At each energization of a magnet C3, a magnet C4 is also energized to operate its armature c5 to return the previously operated slide c to its original position, clear of stop c4. The rotations of the drum Cl are transmitted by gears 25, c10 to a lead screw C7, which moves a block C9 with a pointer c11 along a scale C8. Block C9 is arranged astride screw C7, and slides on a rod 27 of a bail member 28, so that the block can be returned to the start of line position by raising the bail and allowing the block to slide back under the influence of a spring drum C11 into contact with a stop nut C10. The nut C10 is mounted on a screw c12 parallel to the lead screw C7 and rotatable by a handle c13. The nut C10 has a pointer c15 for indicating its position on the scale C8, and carries a switch 34 operated by a projection c14 of the block C9, when it is moved to and from the starting position. The lead screw C7 is slightly adjustable endwise against action of spring c18 by a cam surface c19 formed on handle c13 and engaged by a roller at the end of the shaft of the lead screw C7, so that in any position of stop nut C10, the block C9, when in contact with the nut, accurately engages the thread on screw C7. Space counter. A member sliding on scale C8 carries a pointer c21 and a ratchet bar c25. Every time the space bar is depressed, a rotary solenoid C13 is energized to operate a pawl C23 to advance the slide, a pawl c24, preventing its return. At the end of a line, pawl c24 is raised by a solenoid C14. Pawl c23 has an end-overlying pawl c24. and is thus raised at the same time so that slide c12 returns to its initial position under the action of a spring c22. At the same time, the release magnet C4 is energized so that the drum shaft rotates until an arm c9 thereon meets a removable detent 36 to stop the lead screw in start-ofline position. Also. a solenoid C15 is operated to raise the block C9, which is returned to stop nut C10 by spring C11. Line remainder computor. After a line has been composed the line remainder (by which the line is short of the length of a full justified line) is found by means of a grid plate D movable in guideways 40 in front of a similar stationary grid D1, the grids having lines and spaces of equal width. A photo-electric cell D2 and a lamp D3 are mounted on opposite sides of the grids. Normally, grid D is held by a spring d2 against a stop 41 in such a position that the lines of each grid coincide with the spaces on the other, and no light can pass from the lamp to the photo-electric cell. The end of the line is in the justifying zone when pointer c11 reaches or passes pointer c21, the end of a line of full length being indicated by a stationary plate 42. A solenoid D5 is energized when the end-of-line key is depressed to move grid D to the left. A switch D4 on grid D is closed by plate 42 to sensitize the photo-electric cell which is de-energized when the switch D4 is operated by the projection c14 of the block C9. While the cell is sensitized, it transmits an electrical pulse every time the interline spaces on the grids coincide. As the grid D approaches a spring stop 46, it closes contacts in a switch 38 to deenergize solenoid D5 to allow the grid plate to be returned by a spring d2. The impulses generated by the photo-electric cell D2 are. in number, a measure of the line remainder, and thev are fed to a justification computer which includes a stepping switch actuated by the space bar to count the number of spaces in the line. In the computer, which is of the binary type used in electronic calculating machines, the number of electrical impulses from the photo-cell D2 is divided by the number of word spaces, the quotients then being transmitted from the divider first to a justification storage unit and thereafter through a character width gate to a decoder where it is stored on a relay tree in code form ready for use each time a word space is to be set up during phe photographic period. If it should happen that one pulse or more remains as a fractional part of the quotient, these will be added successively to those already in the spaces until they are exhausted. For example, if there should be. say, 5 pulses left over as the result of such computation, they will be distributed equally among the first five word spaces in the composed line before it is photographed. Recording and decoding mechanism. As shown in Fig. 15, an endless magnetic tape E is perforated at its edges to engage a pair of sprocket rollers E2, E3. The tape is driven past a row of 16 "writing" electromagnets E1, which record signals according to the code for each character as small magnetized dots across the tape. The first 9 magnets record character identification signals, the next 5 character width signals, and the last 2 space and end-of-line signals. During character recording, the tape is advanced by sprocket E2 in steps past magnets E1 until the end-of-line key is actuated, after which it is advanced rapidly to the position whereat the next line is to start. The tape bearing the record forms a loop between sprockets E2, E3, but soon after its recording is finished it is continuously advanced by sprocket E3 to a position where begins the "reading" of the record by a series of