Delivery processing apparatus and delivery processing method

A delivery processing method for a delivery processing apparatus comprising a plurality of regular stackers configured to stack delivery objects;

• a conveyer configured to transport the delivery objects to a designated regular stacker out of the plurality of regular stackers;
• a full sensor and a pre-full sensor configured to detect that a monitored regular stacker out of the plurality of stackers is in an overflow state in which more than a predetermined amount of delivery objects have accumulated, the full sensor configured to output a full, and the pre-full sensor configured to output a pre-full signal;
• a detector configured to detect that a monitored stacker out of the plurality of stackers is in an empty state in which all delivery objects have been retrieved from the stacker;
• and a specifying unit configured to specify a stacker serving as a sort destination of a delivery object, based on address information that is obtained from the delivery object;
• the method comprising:
• controlling the conveyer such that a delivery object is transported to that regular stacker serving as the sort destination, out of the plurality of stackers, that is specified by the specifying unit;
• if the regular stacker serving as the sort destination specified by the specifying unit is in the overflow state, stopping the transport of delivery objects to the regular stacker serving as the sort destination that has gone into the overflow state and assigning, out of the plurality of stackers, a backup stacker that is not correlated with any address information, as a sort destination substituting for the sort destination that has gone into the overflow state;
• and
• after assigning the substitute sort destination, when a regular stacker that had gone into the overflow state goes into the empty state, continuing transport of delivery objects to the backup stacker until the backup stacker goes into the overflow state, and when the backup stacker goes into the overflow state, the main controller then stopping transport of delivery objects to the backup stacker that has been assigned as the substitute sort destination, and resuming the transport of delivery objects to the stacker that has gone into the empty state;
• the delivery objects being retrieved by an operator from the regular stacker;
• successively receiving delivery objects to the regular stacker after the delivery objects being retrieved from the regular stacker;
• and
• controlling to reduce the number of backup stackers when the operating ratio of the backup stackers is low, and to increase the number of backup stackers when the operating ratio of the backup stackers is high.