Horology: time measuring systems or devices – Plural time zones
Reexamination Certificate
1996-04-29
2001-08-21
Roskoski, Bernard (Department: 2859)
Horology: time measuring systems or devices
Plural time zones
C368S047000
Reexamination Certificate
active
06278660
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to time keeping and more particularly to a timepiece which automatically adjusts time as time zone boundaries are crossed.
2. Description of Related Art
People who travel frequently find it necessary to frequently adjust their watches to reflect the correct time for the time zone in which their destination is located. Multiple time zone watches are known which attempt to deal with this problem by simultaneously displaying the correct time for a plurality of time zones. This has the disadvantage that the multiple time zone displays must be independently set in advance. It is possible to set them incorrectly with undesirable results such as missed flights and appointments.
The global positioning system (GPS) is a constellation of twenty-four satellites that orbit the earth twice a day, transmitting precise time and positioning information to anywhere on the globe, twenty-four hours a day. The system was designed and deployed by the U.S. Department of Defense to provide continuous, worldwide position and a navigation data for the use of the United States and allied military forces. The potential for commercial applications of GPS were recognized early in the system's development and a determination made to allow free access to GPS signals with certain constraints applied.
Each GPS satellite broadcast two signals, PPS (Precise Positioning Service) and SPS (Standard Positioning Service). The PPS signal is an encrypted military-access code. The SPS is an unencrypted, spread-spectrum signal broadcast at 1,575.42 MHz. Unlike signals from Land-base navigation systems, the SPS signal is virtually resistant to multi-path and nighttime interference, it is unaffected by weather and electrical noise.
GPS receivers listen to signals from either three or four satellites at a time and triangulate a position fix using the interval between the transmission and reception of the satellite signal. Any particular receiver tracks more satellites than are actually needed for a position fix. The reason for this is that if one satellite becomes unavailable, the receiver knows exactly where to find the best possible replacement. Three satellites are required for two-dimension positioning (i.e. position only). Four satellites are required for three-dimension positioning (i.e. position and elevation). In general, an SPS receiver can provide position information with an error of less than twenty-five meters and velocity information with an error of less than five meters per second. A PPS receiver permits much greater accuracy. The higher accuracy is obtainable with the GPS make it suitable as a precision survey instrument.
THE PROBLEMS
When traveling long distances, timepieces need to be reset when leaving one time zone and entering another. This problem is particularly noticeable aboard common carriers such as trains, buses, ships and airliners which simply do not display public clocks, presumably because of the maintenance required to reset the clocks as the boundaries of time zones are traversed.
Another problem that exists is a need to provide timepieces with the correct time to begin with. Ideally, this would be done automatically. Another problem which exists is the handling of unofficial “time zones” such as some ski resorts, which maintain daylight savings time even in the middle of winter.
Another problem which exists is a need to reduce costs for any implementation of a time zone correcting timepiece.
SUMMARY OF THE INVENTION
The present invention overcomes the problems of the prior art by providing apparatus, processes, systems and computer program products which implement time-zone-tracking for timepieces.
In one form, the time zone tracking timepiece combines a timekeeper, such as a digital clock or watch, with a digital map and a GPS receiver. The GPS receiver tracks the users changing longitude and latitude and compares it with the internal time zone map. When the timepiece crosses a time zone boundary, the presented time is automatically updated.
In a lower cost solution, the invention would utilize, an electromagnetic or infrared link between a GPS linked clock with mapping information, such as might be mounted in a vehicle, and one or more individual timepieces, such as wristwatches which are updated from the GPS equipped station.
In another implementation, fixed locations frequented by long distance travellers, such as airports, hotels, harbors, bus terminals and other such locations can be equipped with the ability to transmit correct time, location and other information to individual timepieces for display. Manual override of the automatic update, could, of course, be included.
The invention is directed to a timepiece which automatically changes time as the timepiece crosses a time zone boundary. The timepiece includes a memory medium storing information about time zone boundaries, a global positioning satellite system, a clock, and a computer configured to change the time of the clock when location information from the global position satellite system indicates a time zone boundary has been crossed.
The invention is also directed to a timepiece which can be remotely updated, a clock and a receiver configured to receive externally supplied update information over a communications link for updating said clock. A transmitter for providing update information can be located on a vehicle or operated from a fixed position. The communications link can be an electromagnetic communications link such as infrared or radio. The update information may simultaneously update the name of the city in which the timepiece is located as a way to verify that the time showing is the time for the city one is currently in rather than a city one previously visited.
The invention is also directed to a system for updating time information, including (1) an update transmitter which has a memory medium storing information about time zone boundaries, a global positioning satellite system providing location information, a system clock, and a computer connected to the memory medium, the global positioning satellite system and the system clock, configured to change the time of the system clock when said location information indicates a time zone boundary has been crossed, and a communications transmitter for sending update information to a remote receiver; and (2) a timepiece, including a timepiece clock, and a communications receiver configured to receive update information for updating the timepiece clock. The computer is configured to periodically connect to a time standard and to calibrate the system clock with time standard information.
The invention is also directed to a method of updating a timepiece to reflect the correct time as a time zone boundary is crossed, including using a navigation system to determine location of the timepiece, and updating the timepiece to reflect the correct time when the navigation system indicates a time zone boundary has been crossed.
The invention is also directed to a method of updating a timepiece to reflect the correct time as a time zone boundary is crossed, including transmitting update information to the timepiece, and receiving the update information at the timepiece and updating the timepiece to reflect current time and location (e.g. the name of the city in which the timepiece is located).
The invention is also directed to a computer program product for implementing time correction for a timepiece including a computer readable memory medium and a computer program, the computer program including steps of comparing information about a current location of a timepiece in relation to a time zone boundary, and updating a clock with a time value appropriate for the time zone of the current location.
The invention is also directed to a computer program product for implementing time correction including a computer readable memory medium and a computer program, the computer program including a routine for receiving at least a time value from a remote source and updating a timepiece with said time val
McDermott & Will & Emery
Roskoski Bernard
Sun Microsystems Inc.
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