Patent GB-666137-A (GB)
Title: Improvements in and relating to automatic spring adjusting and timing devices for timing a balance wheel hair-spring assembly used in clock and watch escapements and the like
IPC: G04D7/12
Filed: 1948-11-30
Abstract: 666,137. Testing hair-spring and balance wheel assemblies of timepieces. KATZ. L. NAMANYI, and EPSYLON RESEARCH & DEVELOPMENT CO., Ltd. Nov. 24, 1949 [Nov. 30, 1948], No. 31045/48. Class 139 [Also in Group XXXV] An apparatus for timing balance wheel and hair-spring assemblies comprises means for mounting such an assembly, means for causing it to oscillate, means for comparing the frequency of its oscillations with a standard time beat and means operable by an electric motor for automatically shortening the effective length of the hair spring until the frequency of its oscillations is the same as that of the standard time beat. The hair-spring and balance assembly 10, 14 to be adjusted is fixed in the jig, shown in Fig. 3, in which the balance staff 12 is positioned between two bearings 26 and the outer end of the hair-spring is gripped between two rollers 36, 38 one of which is rotatable by an electric motor 42, Fig. 4, which is driven when a relay B is energized. The relay B has a holding coil 56, Fig. 5, which is released upon energization of a relay A which receives impulses from an amplifier 50, Fig. 4, connected to a photo-electric cell 48 impinged by a ray of light from a source 46, said ray being interrupted by the outer coils of the hairspring. A standard time beat source 54 is connected in circuit with contacts of the relay A and also with contacts of a relay C. A relay D is energized when relays A and B respect are energized simultaneously. A three position switch 62 is provided to control the circuits of Fig. 5. With the switch 62 in its first position so that the light source 46 is disconnected from its supply, the balance wheel and hairspring 'assembly is inserted in the jig, Fig. 3. Switch 62 is now moved to its second position in which the standard time beat 54 through the relay C sends, impulses to shaded pole electromagnets 44 to cause oscillation of the assembly. Switch 62 is then moved to its third position and the ray from the light source 46 will thereafter at intervals determined by the hair-spring impinge the photo-cell 48 and the resulting impulses from the amplifier 50 will be sent to the relay A which is now in circuit with the electromagnets 44. The assembly is thereby maintained in oscillation. Upon reception of the first impulse by the relay A the time base 54 operates and periodically operates the relay B which remains operated until the circuit of its holding coil 56 is broken by the relay A. During the time that the relay B is energized the electric motor 42 operates to rotate the roller 38 and so shorten the effective length of the hair-spring. When the relays A and B eventually operate simultaneously the relay D, Fig. 5, is energized to cut off the light source 46 and to give a signal, by means not shown, that the timing operation has been completed. The required constant time beat source may include a high frequency crystal oscillator or frequency standard connected to a series of multivibrators. A plurality of jigs each successively brought into operative relation with the light source may be provided.