GB864268A - - Google Patents

Abstract

864,268. Balanced recording systems. VYZKUMNY A ZKUSEBNI LETECKY USTAV. April 18, 1958 [April 25, 1957], No. 12344/58. Class 40 (1). [Also in Group XIX] Signals are recorded by apparatus comprising a stylus mounted on a carriage which runs on rails carried by a body which in turn has a toroidal excitation winding and pick-up coils sensing angular displacement of the body; the output of the coils is amplified and energizes a motor which drives the carriage and rebalances the system. In Fig. 1 the carriage 5 carrying a recording stylus 14 runs on rails 23 which are attached to the ends of the body 1, and the weight of the carriage tends to twist the body around its support 13. A toroidal winding 3 carries A.C. and induces voltages in pick-up coils 2 which are representative of the amount of twist. A quantity to be measured produces a torque in the arm 11 and by a similar arrangement a voltage is induced in the coil 22 indicative of the value of the quantity. The two induced voltages are fed in opposition to an amplifier 12 whose output is used as an error signal to drive a two-phase induction motor 10, the other phase of which is fed with A.C. from the supply. The motor drives a roller 9 and thus moves a wire 8 which passes over pulleys 7 and is attached to the carriage 5. If the input quantity changes, the amplifier will energize the motor and move the carriage to a new position where its weight will balance the twisted arm 11 in a different angular position. The distance l is then a measure of the input quantity and the stylus 14 marks the chart 15 accordingly. The device 11 can be part of a dilatometer, manometer, thermometer, level indicator or balance or other device based on the principle of Specification 837,288, or may be attached to a D.C. amplifier fed with a voltage representing any electrical quantity as in Specification 826,799. Alternatively the supply to the pick-up can be cut off and the system balanced against a mechanical force exerted downwards on the right-hand pulley 7, e.g. from a pressure diaphragm. Other applications are a pH meter, spectrometer, photocolorimeter and polarograph. A control function can be obtained by providing a contact on the carriage 5 to cooperate with two contacts on the rail 23. In a modification (Fig. 2, not shown) the motor 10 is replaced by two units extending lengthwise along the rails and provided with an energizing coil, so that the carriage 5 acts as an armature.