Variable elevator up peak dispatching interval

An elevator system including a group of elevators for servicing a plurality of floor landings divided into contiguous zones in a building, comprising:

• group controller means, including hall call means for registering calls for up and down service at each of side landings and signal processing means for exchanging signals with each of said elevators, responsive to said hall call means and to said signals indicative of conditions of said cars for determining the zone in which each car is located, for assigning cars to zones, for determining empty zones, for determining the floor of highest and lowest floor calls in each zone, for providing zone demand signals to the cars to command the cars to move upward or downward in the building to fill empty zones with unassigned cars and to cause assigned cars to reach floors in their respective zones where floor calls are registered, for determining up peak traffic conditions, for forcing cars from selected zones in the high end of the building to the main landing in response to up peak traffic conditions, for dispatching cars from the main landing at intervals in response to up peak traffic conditions and for issuing stop commands to each car in response to said signals indicative of conditions of said car indicating that the committable floor position of said car coincides with the floor landing of an empty zone or a floor call for which a zone demand signal has been provided to said car, for determining from car calls registered in any car dispatched from the main landing of the building in response to up peak traffic conditions the approximate round trip time required for such car to service such car calls and return to said main landing, and for varying the dispatching interval in accordance with said approximate round trip time;
• each of said elevators including a car, car motion means for providing and arresting the motion of said car, means for registering car calls for service required by passengers therein, and a car controller means for providing signals indicative of conditions of said car, for controlling said car motion means to cause said car to move in a selected up or down direction and to stop in response to said signals indicative of conditions of said car and to signals received from said group controller means;
• characterized by said signal processing means comprising means for determining the number of cars currently at said main landing and for altering said dispatching interval in accordance with the number of cars at said main landing.