Patent GB-442283-A (GB)
Title: Improvements in or relating to the remote control of time indicating devices
IPC: G04G9/04
Filed: 1934-07-05
Abstract: 442,283. Electric clocks. WEIBULL, E. H. W., Saltsjobaden, Sweden. July 5, 1934, No. 19775. [A Specification was laid open to inspection under Sect. 91 of the Acts, Jan. 7, 1935.] [Class 139] The invention relates to clock systems wherein a master clock transmits mutually different selective regulating current .impulses at even intervals of time, for example hours, ten minutes intervals, minutes, &c. to a receiver provided with a plurality of selective members each responsive to a corresponding one of the selective impulses and adapted to actuate under the influence of the impulses an arrangement for indicating corresponding moments of time. According to the invention, the selective members in the receiver are grouped in three or more series, two of which represent time unit intervals of a higher and of the next lower order respectively, e.g. hours and minutes, while the members of a third series also allotted to the lower order represent time intervals of an intermediate length, e.g. tens of minutes. The impulses are transmitted over existing electrical networks or by wireless and may consist of alternating current impulses of different frequencies or of modulating impulses transmitted by a common carrier wave. The frequencies used are kept within one octave to avoid harmonic &c. interference. As shown in Fig. 1, the receiver elements comprise twelve tuned oscillatory circuits A1 B1, A2 B2 . . . A12 B12 to indicate hours, six tuned circuits L1 C1, L2 C2 .... L6 C6 to indicate tens of minutes and ten tuned circuits D1 E1, D2 E2 .... D10 E10 to indicate minutes. The tuned circuits in each of the three series are connected in series with the secondaries of transformers M, T, P respectively, the transmitted impulses being applied to the primaries of these transformers connected in series. The oscillatory circuits are tuned to different frequencies. and are each connected in parallel with a glow-discharge tube K1, K2 ... K12, G1 G2 ... G6, Q1, Q2 ... Q10. Thus at any time, e.g. 4.58, three series of impulses would be sent continuously, having frequencies corresponding to those of the oscillatory circuits A4, B4 (hours), L5 C5 (tens of minutes) and D8 E8 (minutes), which would resonate. The corresponding glowdischarge tubes K4, G5 and Q8 would strike and indicate the time directly or serve to control other time indicating members. When the glow tubes indicate time directly, their electrodes may have the shape of the corresponding digits, and generally are arranged in various manners in lamp tableaux. Fig. 3 shows an arrangement similar to that of Fig. 1, but wherein the glow discharge tubes G1 G2 ... are provided with a biassing voltage, are inductively coupled to their respective oscillatory circuits, L1 C1, L2 C2 ... through windings N1, N2 .... , and are interlinked by condensers C0 so that the tubes G1, G2 ... strike when the corresponding oscillatory circuits resonate, are maintained alight by the biassing voltage, and are extinguished automatically when the next tube strikes, by the action of the condenser C0 linking these two tubes. In the embodiment shown in Fig. 2, the receiver comprises a main group H indicating hours, for example, and a number of subgroups I, II, II .. &c. for indicating shorter time intervals. The main group comprises the oscillatory circuits L1 C1, L2 C2, L3 C3 ... &c. connected in parallel across the secondary of the input transformer T. The discharge lamps G1 G2 ... are each connected through a resistance R to the biassing voltage + 160 and interconnected by condensers C0 serving automatically to quench a tube when the succeeding tube strikes. The subgroups are similar in construction and operation to the main group but may operate only when the corresponding lamp G1, G2 ... in the main group is alight. Secondary subgroups for marking still shorter time intervals may be similarly connected to each subgroup as at b1, b2, b3. In another embodiment the time is indicated by a vibrating reed type frequency meter W, Fig. 4, having three series of reeds x (hours), y (tens of minutes), and z (minutes). The meter is connected through a transformer t and condenser k to input mains KL, and, where the impulses are transmitted by a carrier wave, a rectifier h is provided to effect demodulation if the meter W has a polarized core. If the core is unpolarized the rectifier is unnecessary however. Modifications. When mechanically vibrating frequency selective members are used, they may be used to give an acoustic indication in addition to a visual indication of the time. The frequency selective members may comprise piezo-electric crystals mounted in vacuum in known manner so that light phenomena occur in connection with their oscillatory condition. The Specification as open to inspection under Sect. 91 also contains the following subject-matter. The time indicating glow discharge tubes may be arranged around the circumference of a clock face to indicate the hour and other time intervals. The selectivity of the impulses transmitted to the receiver may be obtained in ways other than frequency selection, for example, the impulses may have different duration or amplitude. This subject-matter does not appear in the Specification as accepted.