Communications: electrical – Vehicle position indication – At remote location
Reexamination Certificate
1998-11-12
2001-01-23
Swarthout, Brent A. (Department: 2736)
Communications: electrical
Vehicle position indication
At remote location
C340S991000
Reexamination Certificate
active
06177889
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field
The invention concerns a method of controlling at least one transit stop display and a control system.
2. Discussion of Related Art
The estimated waiting time until the next vehicle (bus, streetcar) of a predetermined line arrives, is signalled to the user of the local public passenger transit by transit stop displays. This requires performing a switch-over or switch-off of the waiting time display when the vehicle's distance from the stop is under 100 meters. The radio control of the transit stop displays by the control center is not suitable for that purpose because the error tolerances are too large, particularly those which determine the location data of the vehicle. With a waiting time display that is controlled in intervals of one minute, it can therefore happen that a remaining waiting time of 1 minute is signalled when the vehicle has already reached the stop.
Roadway-inserted induction loops are known, which can be used to trigger actions when they are passed over. However in the case of a transit stop display control, considerable hardware and software problems would occur since vehicles from different lines must be differentiated.
The use of a remote radio control such as is used for the priority switch-over of a traffic light is also linked to considerable drawbacks. The vehicles must be equipped with corresponding transmitters and the transit stop displays with suitable receivers. Furthermore this does not solve the problem of the correct trigger time for the emission of the infrared signal.
SUMMARY OF INVENTION
The object of the invention is to present a method and a control system of the aforementioned type which simply and reliably and with sufficient accuracy ensure a switch-over or switch-off of the waiting time display in the vicinity of the stop.
According to the invention, a method of controlling at least one transit stop display, whereby a vehicle transmits an identification signal and current location data to a control center, which calculates an estimated waiting time until the vehicle arrives at least at one stop, and controls the display associated with the respective stop in regard to the visual display of this waiting time, is characterized in that the vehicle transmits a blanking message having a selected range x
1
which triggers a switch-over of the stop display to blanking when the vehicle approaches the stop within a distance of x
2
≦x
1
.
The invention is based on the knowledge that by superimposing a direct control, which is triggered by the vehicle, over the central control of the transit stop display, tolerances and inaccuracies can be eliminated. The passenger no longer receives erroneous information from a still displayed waiting time when the vehicle has already reached the stop.
In further accord with the present invention, the central station generates radio datagrams having a structure and length for controlling display panels of the stop display that are assigned to lines, where a window is provided between the radio datagrams during which the vehicle sends the blanking message. In that case, the vehicle transmits the blanking message during the transmission pauses between the radio datagrams which are generated by the control center. This avoids the simultaneous reception by the stop display of radio signals from the control center and from the vehicle. The emission of a vehicle signal that is heavily dominant with respect to the radio datagram of the control center could also be imagined, so that the blanking message is detected in all instances.
This window variation significantly facilitates the synchronization in time of the vehicle signal by transmitting the window message at the end of each radio-datagram. The window message signals to the vehicle that a window, namely a transmission pause, follows immediately and that the blanking message can be sent. This provides the advantage that the lengths of the radio datagrams must not necessarily be constant. The window length can also vary, provided that its length is sufficient to transmit the blanking message.
Preferably a blanking message is only generated if a stop is next in line, i.e., if the vehicle comes within a distance x
3
of the station
2
where x
3
>x. For reasons of safety the distance x
3
which the vehicle ascertains by means of a relatively coarse location determination, is much longer than the range x
1
of the blanking message. This provides advantages and savings, particularly for stops located far apart, since the blanking message is only transmitted with a certain probability that a stop even exists in the vicinity.
A control system having a simple and economical construction locates the transmission device in the vehicle for transmitting the identification signal and the current location data of the vehicle to the control center, wherein the transmission device is also able to transmit the blanking message. A transmission installation, which is provided anyway in the vehicle for communication with the control center, simultaneously assumes the function of controlling the display. No additional equipment is required in the vehicle nor in the stop display.
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patent: 4799162 (1989-01-01), Shinkawa et al.
patent: 4857925 (1989-08-01), Brubaker
patent: 5613216 (1997-03-01), Galler
patent: 5736940 (1998-04-01), Burgener
patent: 5774072 (1998-06-01), Wu
patent: 4003753 (1991-08-01), None
patent: 2178210 (1987-02-01), None
patent: 9313510 (1993-07-01), None
Patent Abstracts of Japan 10-011699 Jan. 16, 1998, for Japanese Pat. Appl. 08-181622, filed Jun. 24, 1996.
Patent Abstracts of Japan 07-334796, Dec. 22, 1995, for Japanese Pat. Appl. 06-125970 filed Jun. 08, 1994.
Patent Abstracts of Japan 08-329388, Dec. 13, 1996 for Japanese Pat. Appl. 07-130159, filed May 29, 1995.
Alcatel
Swarthout Brent A.
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