Patent GB-1224909-A (GB)
Title: Dictation machine
IPC: H01H15/18
Filed: 1969-01-09
Abstract: 1,224,909. Dictation machines. INTERNATIONAL BUSINESS MACHINES CORP. 9 Jan., 1969 [19 Jan., 1968], No. 1381/69. Heading G5R. When loading means are actuated to load a record into a dictation machine, the head and record are automatically driven to given initial positions and the machine switched to manual control. General.-The machine (Fig. 1) receives a magnetic belt 2 upon which the information is recorded by a head 82 (Fig. 10) on a carriage driven by lead screw 100 (Fig. 4), and manually indexable by lever 16 movable across an index slip 15 and containing a device for marking the slip with instructions. The machine is controlled by a hand-set 36, or, when in the playback mode, by a foot controller. Record loading.-Lever 10 is moved to the right to operate linkages so as to retract roller 63 and rotate switch-operating cam 73 to thereby set a latch 91, disengage via links 85, 87 a set of pawls coupling the carriage to the lead screw, and engage head carriage extension 96 with a reverse lead screw thereby returning the carriage to the extreme right (Fig. 4) "zero" position, whereupon the motor 105 is stopped by a carriage extension (122, Fig. 11, not shown) opening motor circuit contacts. The belt 2 is slipped over mandrel 7 and pushed in to engage a gripper 50, thereby raising the upper gripping jaw free of a rack which would otherwise prevent the gripper retracting if no record were loaded. Lever 10 is moved to the left to retract the gripper beyond the position where the belt abuts flanges on the rollers 63, 64, the gripper engaging a stop to release the belt, and to extend the roller 63 to tension the belt. Reverse rotation of cam 73 operates contacts 75a to energize the motor and operate a clutch 93 to drive lead screw 100 until a pin 92 engages a latch member 84 to disengage the clutch with the lead screw in a "zero" phase condition. The belt continues to be driven until a hole is sensed by a pair of contacts to operate a reverse solenoid 89, normally used for backspacing the carriage, to release the latch 91 and re-engage the head 82 and leadscrew pawls. The machine is now set for operation. If the belt has no locating hole, a button 38 on the handset is momentarily operated to energize the reverse solenoid to free the catch 91 and provide an artificial "zero" position. A lever 23 operates to axially shift the lead screw 100 for fine adjustment of the head carriage relative to a pre-recorded track for optimum tracking, as indicated by signal level meter 21 which also operates as a battery level indicator. Recording and playback.-Selector button 20 is switched to "dictate", "telephone" or "conference", the last increasing the overall gain of the amplifier, button 32 is moved up or to the centre for record or playback respectively and drive is begun when bar 33 is depressed. Button 32 modifies the feedback of the amplifier for optimum frequency response by controlling two relays, one of which is relatively slow to operate to mimimize "clicks" &c. The bar 33 may simply be held, or latched by sliding to the left. The modulation level and belt speed may be adjusted by minor controls (24, 25, Fig. 2, not shown) and a switch (27) operated to select 10 or 20 minutes of recording time. A lamp 35 is lit to indicate recording. The head 82 has separate record/playback and erase/bias windings (Fig. 25c, not shown). Erase.-Is effected by moving lever 40 to press a full width permanent magnet 157 against the belt. The lever may be latched and contacts operated to drive the belt at a higher speed for at least one revolution, then the latch is released. Back- and forward-spacing.-Operation of button 32 downwards (backspace) or 38 upwards (forward space) energizes the corresponding solenoid 89, 88 to rock a linkage (Fig. 13, not shown) coupled to shift a rod (175) extending parallel to the lead screw to engage a tab (A, B, Fig. 14, not shown) on, and thereby rock, one or other of two pawl assemblies (101) to move the carriage by one thread. Alternatively, a capacitor circuit may be interposed in the solenoid circuit to move the carriage in increments of 6 or 12 seconds of recording time according to the setting of recording duration switch (27) above. To permit the first few recorded words to be properly reproduced, a margin control (Figs. 22-24, not shown) comprising a face cam (210) engageable by a pointer (212) on the carriage, is adjustable; and to prevent damage by the pointer, a second movable pointer (218) is provided. Manual head positioning.-Depression of knob 16 moves bail 87 to disengage both pawl assemblies (101) allowing free movement of the carriage by sliding knob 16. To ensure correct repositioning of the pawls relative to the lead screw thread, a probe (199, Figs. 20, 21, not shown) is operated by the bail to locate in the threads on release of the bail 87 and automatically adjust the carriage position. Ancillary features.-Dynamic braking of motor 105, whose speed is regulated by a tachogenerator and accompanying circuit (Q2- Q8, Fig. 25, not shown), is effected by a transistor (Q1) which short-circuits the motor. A warning buzzer sounds near the end of the belt or if the selector button 20 is in the wrong mode, and the machine auto-stops at the end of the belt. Modifications.-Another machine, primarily intended for playback only, is also described (Figs. 15, 19, not shown), but is generally similar in operation to the above complete dictation machine. The machine is under foot control whereby pressure exerted on the controller in three different positions controls playback and back- and forward-spacing. The machine includes a device (Fig. 16, not shown), whereby upon halting playback, the carriage is automatically back-spaced so that the last few words are repeated when playback recommences.