Multiple speed stroboscope device
AssigneeU.S. Philips Corporation
InventorAlfred Seitz
Life of this patent
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Abstract
A stroboscope device for a record player for monitoring at least two speeds such as 331/3 and 45 r.p.m. A turntable rim may be provided with a single stroboscope pattern for the relevant speeds. As they pass a light pulse generator, the marks of the stroboscope pattern are optically comparable with light pulse trains produced by a light pulse generator at one of a plurality of frequencies obtained from a given or a-c mains frequency.
Claims8
A stroboscope device for a record player for monitoring nominal rotational speeds of approximately 331/3 and 45 r.p.m., comprising a single stroboscope pattern ring, and light pulse means for illuminating the pattern with a light pulse train having a pulse frequency derived from a given frequency, the light pulse generator producing a non-overlapping steady image at the nominal speeds.
A stroboscope device for monitoring at least two different nominal speeds, the higher nominal speed being a non-integral-multiple of the lower speed, comprising a single stroboscope pattern, and a light pulse means for illuminating the pattern, said means including
- means for generating a master frequency from a given frequency,
- divider means for generating a pulse frequency from said master frequency,
- a light pulse generator arranged for illuminating the stroboscope pattern, and
- means for applying a train of current pulses at said pulse frequency to the light pulse generator for optical comparison of the pattern speed with said nominal speeds.
Dependencies are inferred from the claim text.