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US 5,363,348 AGranted
High resolution, remotely resettable time clock
OwnerMadhav N. Damleinventor
Life of this patent
Estimating the term…
Abstract
A low cost, remotely resettable wall clock or the like is provided, which is driven by a conventional quartz crystal oscillator system, for example. On a once a day basis, a reset signal is received from a local broadcast station, which serves to reset the clock to a predetermined reset time, typically 02:00:00 am. The system includes means for automatic startup of the clock without setting of the hands, eliminating the need for mechanical reset facilities. The control system includes means for automatically advancing or retarding the clock reset by one hour, to accommodate the beginning or the end of day light saving time. The economical design of the clock system enables it to be suitable for household as well as commercial use.
Claims13
In a time keeping system of the type comprising a clock having hours, minutes, and seconds time indicating elements, pulse actuated drive means for progressively advancing said time indicating elements in increments of one second or less, and remotely located radio signalling means for periodically synchronizing said clock with respect with said signalling means, the improvement characterized by
- (a) a crystal oscillator pulse generator for operating said pulse actuated drive means and operative to advance said time indicating elements with an expected level of accuracy within a few seconds per day,
- (b) a resettable pulse counter actuated by said pulse generator and operative to count pulses of said pulse generator in increments corresponding to increments of advance of said time-indicating elements,
- (c) said radio signalling means being adapted to generate a clock-reset signal at a precisely predetermined reset time each day,
- (d) control means operative when the count of said pulse counter is a predetermined number of seconds earlier than said predetermined reset time to increase the rate of pulses delivered to said pulse actuated drive means, temporarily increasing the rate of movement of said time indicating elements,
- (e) said predetermined number of seconds being at least slightly greater than the expected level of accuracy of said pulse generator,
- (f) position sensing means operative when said time indicating elements are position precisely at the predetermined reset time for interrupting the flow of pulses to said pulse actuated drive means, whereby said time indicating elements remain fixed at the predetermined reset time,
- (g) rf receiving means in said clock for selectively receiving said clock reset signal, and
- (h) reset control means, responsive to receipt of said clock reset signal, for simultaneously resetting said pulse counter to its starting value and for resuming the flow of pulses to said pulse actuated drive means.
5 more elements
In a time keeping system of the type comprising a clock having hours, minutes, and seconds time indicating elements, pulse actuated drive means for progressively advancing said time indicating elements in increments of one second or less, and remotely located radio signalling means for periodically synchronizing said clock with respect with said signalling means, the improvement characterized by
- (a) a crystal oscillator pulse generator for operating said pulse actuated drive means and operative to advance said time indicating elements with an expected level of accuracy within a few seconds per day,
- (b) a resettable pulse counter actuated by said pulse generator and operative to count pulses of said pulse generator in increments corresponding to increments of advance of said time-indicating elements,
- (c) said pulse counter including a seconds counter,
- (d) said radio signalling means being adapted to generate a clock-reset signal at a precisely predetermined reset time each day,
- (e) rf receiving means in said clock for selectively receiving said clock reset signal,
- (f) control means becoming initially operative when the count of said pulse counter is a first predetermined number of seconds earlier than said predetermined reset time, and remaining operative until a second predetermined number of seconds after said predetermined reset time, to selectively process said clock reset signal,
- (g) said first and second predetermined number of seconds being at least slightly greater than the expected level of accuracy of said pulse generator,
- (h) circuit means for determining the value of said seconds counter upon receipt and processing of said clock reset signal,
- (i) reset control means, responsive to receipt of said clock reset signal, for temporarily increasing or decreasing the rate of flow of pulses to said pulse counter and to said pulse actuated drive means to add or subtract the number of pulses corresponding to the number of seconds said seconds counter was leading or lagging said clock reset signal.
6 more elements
An analog clock remotely resettable by radio signal which comprises
- (a) a pulse generator comprising a crystal controlled oscillator for generating a stream of accurately timed pulses,
- (b) a plurality of geared-together, changeable time indicating elements for indicating respectively hours, minutes and seconds,
- (c) a single, pulse actuated motor, driven by said pulse generator, for controllably advancing said time indicating elements in increments of one second or less,
- (d) pulse counting means for counting said pulses in increments corresponding to the minimum increment of advance of said time indicating elements,
- (e) an rf receiver for detecting a daily high accuracy clock reset signal from a remote broadcast source, and
- (f) means for sensing the condition of said pulse counter at the instant of said clock reset signal and thereby determining the exact number of time increments said clock is fast or slow,
- (g) means operative to effect the addition or substraction of an exact number of pulses from a constant regular stream thereof to advance or retard the position of said time indicating elements an exact number of increments to synchronize exactly with a time reference established by said clock reset signal.
4 more elements
A clock remotely resettable by radio signal which comprises
- (a) a pulse generator comprising a crystal controlled oscillator for generating a stream of accurately timed pulses,
- (b) changeable time indicating elements for indicating respectively hours, minutes and seconds,
- (c) a pulse actuated means, driven by said pulse generator, for controllably advancing said time indicating elements in increments of one second or less,
- (d) pulse counting means for counting said pulses in increments corresponding to the minimum increment of advance of said time indicating elements,
- (e) an rf receiver for detecting a daily high accuracy clock reset signal from a remote broadcast source,
- (f) means operative by the addition or substraction of pulses from a constant regular stream thereof for adjusting the position of said time indicating elements to synchronize exactly with a time reference established by said clock reset signal,
- (g) means responsive to said counter reaching an apparent time a few seconds in advance of said clock reset time for controllably advancing the rate of flow of pulses to said pulse actuated means, whereby said time indicating elements are driven to a position corresponding to said clock reset time a few seconds in advance thereof,
- (h) means responsive to said time indicating elements being driven to said last mentioned positions to interrupt the flow of pulses to said pulse actuated means, whereby said time indicating elements become fixed, and
- (i) means responsive to the receipt of a clock reset signal from said remote broadcast source for resetting said pulse counter to zero and resuming the regular flow of pulses to said pulse actuated means.
6 more elements
A clock remotely resettable by radio signal which comprises
- (a) a pulse generator comprising a crystal controlled oscillator for generating a stream of accurately timed pulses,
- (b) changeable time indicating elements for indicating respectively hours, minutes and seconds,
- (c) a pulse actuated means, driven by said pulse generator, for controllably advancing said time indicating elements in increments of one second or less,
- (d) pulse counting means for counting said pulses in increments corresponding to the minimum increment of advance of said time indicating elements,
- (e) an rf receiver for detecting a daily high accuracy clock reset signal from a remote broadcast source,
- (f) means operative by the addition or substraction of pulses from a constant regular stream thereof for adjusting the position of said time indicating elements to synchronize exactly with a time reference established by said clock reset signal,
- (g) said rf receiver being operative to distinguish among a normal daily reset signal and special reset signals corresponding to the days of the start and end of daylight saving time,
- (h) first circuit means responsive to the receipt of a reset signal corresponding to the start of daylight saving time to add pulses corresponding to 3600 seconds to said pulse counting means and to said pulse actuated means, and
- (i) second circuit means responsive to the receipt of a reset signal corresponding to the end of daylight saving time to subtract pulses corresponding to 3600 seconds from the flow of pulses to said pulse counting means and to said pulse actuated means,
- (j) said first circuit means comprising means to double the rate of pulses to said pulse counting means and to said pulse actuated means for a period of 3600 seconds.
7 more elements
Dependencies are inferred from the claim text.