The following is a U.K. Patent Application filed on February 14, 1958 by The English Electric Company Limited, Harold Aspden being one of the three co-inventors. It was published on February 28, 1962.
Commentary: This is a patent having quite broad claim coverage
relating to electrical control systems which respond according to the phase
angle between two alternating signals.
Claim 1 reads: A phase angle comparator comprising reactive circuit means for shifting the phase angle between two alternating electrical signals by a predetermined amount and polarity sensitive electrical circuit means for determining the sense of the polarity change of one of the signals whilst the other signal has a chosen polarity.