Patent GB-762914-A (GB)
Title: Electric transducer circuit and system
IPC: H01J65/04
Filed: 1954-09-13
Abstract: 762,914. Electric control systems. LION, K. S., and SHEETZ, J. W. Sept. 13, 1954, No. 26451/54. Class 40 (1). [Also in Groups XXXVI and XXXIX] A transducer or electric translator is based on the principle that if a gas-filled tube 1, Fig. 1, having internal electrodes 3, 5 is subjected to an alternating electric field sufficient to ionize the gas, then a unidirectional voltage is developed between the electrodes having a magnitude and polarity determined by the field distribution. According to the invention, input signals-mechanical or electricalvary the field distribution to produce corresponding variations in the unidirectional output voltage. The field may be produced by an oscillator 17 connected between one fixed electrode 3 and a movable external electrode 9 but preferably the other fixed electrode 5 is also energized from the oscillator through a condenser. Movement of the electrode 9 along the tube 1 then produces a unidirectional voltage output at 2-4 as shown in Fig. 2, the central position of the electrode 9 corresponding to zero output. The same effect may be produced by using moving electrodes 3, 5 with a fixed electrode 9, which may then be inside the tube 1. Again, the output may, alternatively, be derived from electrodes 3-5, Fig. 10, capacitively coupled to the electrodes 6-8 fed from the oscillator 17. The variations in field distribution may, alternatively, be produced by a movable shield electrode, Fig. 11 (not shown), or by a multiple movable electrode system, Fig. 12 (not shown). In another arrangement, Fig. 3, the tube 1 is disposed axially in the electric field produced by the oscillator 17 between electrodes 19, 21, axial movement of the tube relative to the electrodes producing the output at 2-4 as shown in Fig. 2. In a further arrangement, Fig. 4, the oscillator 17 is connected to the electrodes 3, 5 of a " pea "-type neon tube 1 through condensers C, Cv, the field variations being produced electrically by varying C or Cv. Both condensers C, Cv may be differentially operated in unison with the movements of the electrode 9, Fig. 7 (not shown). Variable inductors or non-linear impedances may be used in lieu of C, Cv. In a modification of the Fig. 4 arrangement, the tube 1, Fig. 19, is connected in the diagonal of an impedance bridge 101- 103-105-107 energized from the oscillator 17, the input signal varying the displacement of the ring electrode 9. If, however, the bridge arm impedances are varied by the input, the electrode 9 may be dispensed with. An L-C circuit tunable through the frequency of the oscillator 17 may be connected across the output terminals of any of the above embodiments, variation of the tuning, Figs. 16, 17 (not shown), having the same effect as movement of the tube 1 relative to the electrodes (19-21, Fig. 3, for example). Variation of the tuning may thus be used separately, for indication or control purposes, or used together with adjustment of C, Cv. The unidirectional output at 2-4 is normally independent of the frequency of oscillator 17 but may be made dependent thereon by appropriate adjustment of the physical and electrical constants. In such a case the oscillator 17 may be amplitude modulated so that the D.C. output carries the modulation frequency superposed thereon whereby A.C. amplifiers may be used, Fig. 15 (not shown). Applications. Linear dimensions may be measured by displacing the movable electrode 9 accordingly or by relatively moving the tube and electrodes 19, 21, Fig. 3. Linear vibrations, e.g. seismographic, may be similarly measured and recorded, Fig. 14 (not shown). Angular displacement, e.g. of the screw 13, Fig. 1, may be measured by displacing the electrode 9 linearly in correspondence. Alternatively, a rod-shaped movable electrode may be disposed parallel to the axis of a " pea "-type tube, Fig. 8 (not shown), and rotatable about the tube axis, its angular position being indicated by the D.C. output voltage. A gyro pick-off may be similarly constructed. The variable condenser Cv, Fig. 4, or the differential condenser C-Cv, Fig. 7 (not shown), may be rotatably variable in which case its angular position is indicated. Pressure variations may be measured by applying them to a diaphragm, Fig. 6, which with wire meshes 31, 35 on each side thereof functions as a differential condenser, corresponding to C-Cv, Fig. 4. A pressure to be measured may alternatively be applied to produce a corresponding displacement of the electrode 9. Temperature may be measured by a thermocouple arranged to deflect a galvanometer, Fig. 13 (not shown), which moves the electrode 9. Two (or more) variables may be algebraically summed, Fig. 21 (not shown), by translating them respectively into movements of the electrodes 9 of separate transducers the outputs of which are connected in series. The movements of the electrode 9 of one of these transducers may be caused to follow that of the other, Fig. 23 (not shown), by using the series connected outputs to operate a motor which drives the follow-up member. Twodimensional movements may be indicated by displacing the tube 1 in x, y co-ordinate directions relative to two pairs of quadrature electrodes 81-83, 81<SP>1</SP>-83<SP>1</SP>, Fig. 20, fed from the oscillator 17, and co-operating with respective pairs of output electrodes 3-5, 3<SP>1</SP>-5<SP>1</SP> in the tube. This arrangement could be similarly extended to' three dimensions. The external electrode pairs 81-83, 81<SP>1</SP>-83<SP>1</SP> could be fed in quadrature to produce a circular field pattern. In another arrangement, Fig. 22, an input signal at 112-114 deflects a pot magnet coil 109 to vary one of the control condensers C1 of the transducer 1 to produce a corresponding amplified output voltage at 2-4, a portion of which balances the input voltage.