Patent GB-813295-A (GB)
Title: Improvements in apparatus for registering electrical voltages
IPC: G01R13/04
Filed: 1957-04-05
Abstract: 813,295. Voltage measurement. BOFORS A.B. April 5, 1957 [April 21, 1956], No. 11175/57. Class 37. [Also in Groups XIX; XL (b) and XL (c)] A series of instantaneous values of a variable voltage are recorded by causing them to produce cathode-ray (C.R.) tube traces of lengths corresponding to the values and photographing the traces on a moving film. The printed film is used in conjunction with a C.R. tube and photo-electric means to provide numerical evaluation of the recorded traces. Recording.-The variable voltage is fed to circuits IK (see Fig. 1) and the resulting traces on the C.R. tube K are recorded on a moving film F. Comparator unit KP (see Fig. 2), produces output pulses 3 (see also Fig. 6), at the times when saw-tooth waveforms 6 (see also Fig. 5), reach the momentary amplitude of the variable voltage 5. The operation of integrator unit Itg1 is so controlled by trigger unit Tr1 that when the latter moves from its first to its second position a constant voltage is integrated, thus producing a saw-tooth voltage, and when it moves back to its first position the saw-tooth voltage collapses rapidly; the trigger unit is a bi-stable multivibrator and its output is of the form 8 (see Fig. 9). The initiation of the sawtooth voltages at regular intervals is controlled by pulses 2 (see Fig. 4), and the complete recording cycle, by a long pulse 1, the output of mixer unit BL1 being as shown at 4 (see Fig. 7) in which the switch-over levels of the trigger unit are indicated by the dot-dash lines. The output of the integrator unit passes to the C.R. tube K to give corresponding horizontal traces whose intensities are controlled by the pulses 7 (see also Fig. 8). The film is developed and printed to give a black film strip with the voltage values shown as transparent lines. Evaluation of recorded data.-The film is played back between a C.R. tube K (see Fig. 10) and a photomultiplier tube FM behind a slotted plate B. " Feeler " sweeps at the repetition rate of pulses 11 from generator PG (see Figs. 11 and 12), traverse the C.R. tube screen and are brightened by pulses 14 (see Fig. 15), from trigger unit Tr2. When a transparent line on the film appears before the slotted plate, impulses from the photo-multiplier tube appear after amplification, as shown at the beginning of waveform 15 (see Fig. 16, and trigger unit Tr1 gives a long negative pulse 16 (see Fig. 17, causing integrator unit Itg1 to generate a saw-tooth waveform (see Fig. 24, not shown), controlling the " play-back " traverse of the C.R. tube beam (see waveform 24, Fig. 25). During the " play-back " sweep the beam is deflected so as to zig-zag by waveform 28 (see Fig. 29) from amplifier X-F; pulses 19 (see Fig. 21), whose number corresponds to the length of the transparent line on the film, result and are fed into a computer R1 which leads to figure-registering apparatus Reg producing type-written figures or punched tape. General.-The same C.R. tube is used for recording and evaluation and the recording circuits form part of the evaluation circuits. Several varying voltages may be fed sequentially into the apparatus via a switch.