Patent GB-513988-A (GB)
Title: Improvements in or relating to apparatus for timing periodic impulses
IPC: G04D7/12
Filed: 1938-03-08
Abstract: 513,988. Recording-apparatus. GIBBS, T. B. March 8, 1938, No. 7295. Convention date, March 25, 1937. [Class 106 (iv)] [Also in Group XVIII] Apparatus for timing periodic impulses, e.g., the ticks of a watch, comprises a record strip and a hammer responsive to the impulses to strike the strip against a series of elements (teeth) moving at constant speed across the strip, the succession of marks by their transverse position giving a direction indicative of the timing of the impulses relative to a standard, thus enabling the accuracy of a watch to be checked and adjusted. A synchronous motor 34 drives the record strip 74, an ink ribbon 102, and a disc 54 (or 55) immediately behind 54 with teeth 56 (or 57). The hammer 80 is actuated at each tick of the watch being tested by polarized electromagnets 39, 40 which receive their impulses from a microphone through electric amplifying means, Fig. 15 (not shown). The discs 54 and 55 are attached to a shaft 45, Fig. 8, which is driven at exactly 5 r.p. sec., the driving synchronous motor 34 being fed through a constant-frequency generator. The strip and ribbon guides and the contact surface of the hammer are curved to conform to the tip circle of teeth 56 and 57. If the watch is correct the hammer will give impressions.on the strip 74 from the same tooth each time at precisely 1/5th second intervals so that the series of marks will be parallel to the edges of the moving strip 74 as at 275, Fig. 14. If the watch is fast or slow the marks will incline to the right or left respectively, as at 276 and 277, the inclination indicating the amount the watch is fast or slow. The tape shows through a window in the lid 3 of the casing, Fig. 1 (plan), and a spindle with an outside knob 14 has attached to it a rod 18, below the window and just above the tape, and a pointer 15. The rod 18 is adjusted parallel to the marks and the pointer then gives the amount of error on a calibrated scale 13. The disc 54 has eleven teeth 56 which coact with hammer 80 in testing watches or clocks which beat five or five and a half times per second. Disc 55 has twelve teeth 57 to test six-beat watches. For the latter, the discs are shifted axially by pulling out a knob 9 on the front of the casing-parts 59, 58, Fig. 7 (not shown)-so that disc 55 is in the plane of hammer 80 instead of disc 54. The paper strip 74 passes through a rear slot 4, under the hammer and out of a front slot 5, the paper feed being by means of an upper roller 144 and a lower roller 141, Fig. 4 (not shown). This lower roller is positively driven by the synchronous motor through a gear train which may be broken by depressing a lever 7, Fig. 1, and Fig. 6 (not shown), to interrupt the paper feed when desired. The ink ribbon 102 passes from spool 103 to spool 104, the drive being through wheels 108 and 110. When spool 104 is full (the end portions of the ribbon are red) the ribbon feed isreversed by a knob 6 which moves shaft 109 axially so that wheels .108 and 110 are disengaged and wheels 106 and 112 are engaged. The hammer 80 is attached to a U-strip 81 pivoted at 82, 83 and to which are attached vertical pullrods 85 operated by armature extensions 90 of the magnets 39 and 40 which are energized at each tick. In a modified construction, Figs. 16 and 17 (not shown), the mechanisms are rearranged so that as soon as the tape is marked it issues from the front slot, so that the record may be immediately torn off and sent with the test watch for adjustment of the latter.