Patent GB-190508168-A (GB)
Title: Improvements in and relating to Electric Telegraph Apparatus and in particular to Devices for Indicating at a Distance the Position of a Pointer, Needle, or the like.
Inventor: USENER HANS
Filed: 1905-04-17
Granted: 1905-09-21
Abstract: 8168. Usener, H. April 17. Electric clocks.-Relates to apparatus for indicating electrically at a distance the position of a pointer, needle, or the like, such apparatus being applied to the transmission of orders on board ship, to the indication of the readings of a compass needle, water-gauge, or wind vane &c., to the actuation of a clock-hand, or to other purposes. The receiving-instrument consists of two crossed coils in a magnetic field, and the arrangement is such that the pointer can be turned through a complete revolution in the same direction and the movement repeated if necessary, the pointer always following the movements of the transmitting-handle. In the arrangement shown in Fig. 2, the crossed coils 43, 44 are pivotally mounted in the field of a magnet 47. The pointer is carried on the axle or pivot. The coils are connected at one end to a wire 52, the other ends being connected to a ring 40 and a pivot 41, Figs. 2 and 3. Current from a dynamo 13 passes through a subdivided resistance 14, 15, the sections of which are connected to contact-studs 16, 17, 18, &c., which are cross-connected in the manner indicated by the dotted lines. The two part-rings 38, 39 are connected to the terminals of the resistance 14, 15. The switch-handle 42 bears contact-plates 54, 56 adapted to connect the contact-studs to the pivot 41, and to bridge over the rings 40 and 38 or 39 respectively. The wire 52 being connected through the contact-studs 31, 21 to the mid-point 53 of the resistance 14, 15, the potential applied to the terminals of the coil 44 is ether zero (when the switch lever is in one of the two positions midway between the part-rings 38, 39) or is one-half the potential of the dynamo, applied in one or other direction according as contact is made with one or other of the part-rings 38, 39. The direction assumed by the pointer and crossed coils is determined by the resultant of the magnetic force due to the currents in the coils 44, 43. The last-named current is dependent on the potential applied between the wires 52, 49, this being either one-half of the potential of the dynamo, in either direction, or a fraction of it determined by the degree of rotation of the switch arm 42. Owing to the provision made for the reversal of both of the component currents when the respective coils pass through the plane of the magnetic field, continuous rotation is rendered possible. The sections of the resistance 14, 15 are given such values that the resultant magnetic force of the crossed coils moves through equal angular distance when the switch handle is moved from stud to stud. The wire 52 may in some cases be dispensed with, four wires being then sufficient for an order and acknowledgment apparatus used in conjunction. In the arrangement shown in Fig. 2, the resultant magnetic force due to the crossed coils has a value which varies considerably as the switch handle is rotated. In order to give it a more constant value, the part-rings 38, 39 may be subdivided, the sections being connected by suitable resistances. In this way the component due to the coil 44, instead of having one positive or negative value only apart from zero, may be given such successive values as to give an approximately constant value to the resultant, or the part-rings may be replaced by contact-studs equal in number to the studs 16, 17, &c. and connected by resistance coils. In this case the resultant can be made the same for all positions. Fig. 9 shows a modification in which the part-rings are replaced by contactstuds connected in pairs, as shown on the righthand side of the Figure, to the outer studs, a variable potential being thus applied to the coil 44. Only one set of resistances, namely the series 14, 15, is in this case required. Instead of using two sets of contact-studs, one set only may be used, two contact-arms being arranged at rightangles, as shown in Fig. 10. The last-named Figure shows two transmitters, the one being connected to the pivoted crossed coils 43, 44, and the other to the similarly-disposed field magnets 430, 440, which take the place of the permanent magnets shown in Fig. 2. This combination enables a want of agreement between the two transmitters to be indicated at the receiver, the pointer of which makes no movement as long as the direction of the magnetic resultants of the pivoted coils and field magnets are varied in the same manner. Any variation between the indications of a compass and a gyroscope, for example, can be indicated by this means. Ring windings may be substituted for the polar and crossed coils.