Patent GB-446112-A (GB)
Title: Improvements in or relating to apparatus for recording the rate of a watch
IPC: G04D7/12
Filed: 1934-12-03
Abstract: 446,112. Testing timepieces. WESTERN ELECTRIC CO., Ltd., Bush House, Aldwych, London.-(Electrical Research Products, Inc. ; 195, Broadway, New York, U.S.A.) Dec. 3, 1934, No. 34727. [Class 139] Apparatus for testing the running of watches, clocks, and other clockwork mechanisms, comprises a record surface mounted on a cylinder rotated at a constant speed, and a stylus moving at a constant speed parallel to the cylinder axis which records the ticks of the timepiece on the record surface. Preferably, the cylinder is rotated at a frequency equal to that of the ticks, so that if the timepiece is correct the ticks are recorded in a line parallel to the cylinder axis. Errors in the timing of a timepiece are then indicated by the divergence of the recorded line from this parallel and are read off directly against the calibrated record surface, for example, in seconds per day. In the embodiment shown, a watch is held in a spring holder 2, Figs. 1, 2, rotatably mounted so that the watch may be tested in various positions. The tick vibrations are mechanically transmitted through a stiff wire 3 to a magnetic converter 4, Fig. 1. Voltages in the converter 4, corresponding to the vibration trains due to the ticks are amplified at 6, 7, and applied to a trigger discharge device, for example, a " Thyratron " (Registered Trade Mark) tube 13, which is maintained in an oscillatory condition to enhance its effect, and actuates a stylus 20 electromagnetically corresponding to the ticks. The ticks may also be heard in a headphone plugged into a jack 12. The record cylinder 30, Figs. 2, 3, 4, is driven through gearing 56, 57, by a synchronous motor 22, started by an induction motor 23 driving through gearing 40 ... 44 and an overrunning clutch 45, a shaft 46 carrying a wheel 55 meshing with wheel 56 of the synchronous motor. Splined to shaft 46 is a sleeve 47 carrying gears 48, 49 whereby a shaft 51 located in a fixed sleeve 53 may be driven at two different speeds, either through gearing 48, 50, or 49, 54. The stylus 20 and its operating magnet 66 are carried on a member 65, slidable on the sleeve 53 and adapted to be driven by a spring-pressed rack member 61 slidable therein and normally engaging the threaded portion 52 of shaft 51. The position of the stylus is indicated by an arm 38 rigid with the slide 65 projecting through a slot in the casing 32, Fig. 2. The record strip is mounted as a roll 73 on a shaft 72 within the cylinder 30, passes through a slot in the periphery thereof and is held in position around the cylinder by spring clamps 74. The record marks are made by the stylus 20 through a carbon ribbon 33 advanced from a roller 68 over guides and wound on to a roller 69 by a ratchet feed device 35. Operation. A handle 36, Fig. 2, is pressed in and turned anticlockwise, whereby a spring 86, Fig. 3, depresses a plunger 87 to close switch 24 to the starting motor 23 which starts the synchronous motor 22. Turning of the handle 36, through arms 79, 80 thereon, first disengages the spring-pressed rack 61 from the thread 52 and then through arms 81 returns the slidable member 65 and with it the stylus 20 to the left or starting end of the sleeve 53. When the synchronous motor has taken over the drive, the starting handle is released and returned to normal by a spring 75, where it may be locked by rocking a latch 97 to the dotted position. The slide 65 is now driven by the thread 52 to the right until in the position shown, a projection on the slide 65 rocks a spring 90 to open switch 25 and stop the synchronous motor. The completed record is now pulled away and torn off against a cutter 31 which action automatically positions a fresh length of record strip around the cylinder. The two-speed drive to the shaft 51 enables the stylus to traverse the cylinder in either five or thirty seconds for different tests. For testing timepieces other than watches, the ticks are transmitted to the holder 2 through a rigid wire. According to the Provisional Specification, the tick marks may alternatively be recorded on a sheet moving in a horizontal plane at a constant speed and compared with standard marks thereon, or the ticks could be recorded along a diameter of a revolving disc.