System for counting persons in a high density mobile storage system

Apparatus for storing selective material comprising:

• a. first and second stationary spaced apart structures anchored to a building floor and having respective opposed first and second ends;
• b. carriage means for storing the selecting materials and for rolling along the building floor between the stationary structures and thereby cooperating therewith to open and close multiple aisles, the carriage means defining a plurality of passages therethrough;
• and
• c. photoelectric means installed solely in the stationary structures for counting the number of persons in all of the aisles, the photoelectric means comprising at least one light beam emitter installed in each stationary structure proximate the first end thereof, and at least one light beam receiver installed in each stationary structure that receives the light beam that is emitted by an associated light beam emitter and that passes through a respective passage in the carriage means.

A method of controlling high density mobile storage comprising the steps of:

• a. installing at least two photoelectric light beam emitters solely proximate an end of selected ones of a first stationary structure and a second stationary structure;
• b. installing at least two photoelectric light beam receivers on the second stationary structures other than the selected ones of the first and second stationary structures;
• c. providing a mobile carriage between the first and second stationary structures, the mobile carriage having opposed ends and cooperating with the stationary structures to define aisles therebetween;
• d. passing a pair of light beams emitted by the photoelectric emitters through the mobile carriage solely proximate an end thereof, and receiving the light beams by the photoelectric receivers;
• e. sequentially breaking the light beams emitted by the photoelectric emitters to count a person entering or leaving any aisle;
• and
• f. controlling the mobile carriage to roll toward and away from the first and second stationary structures in response to counting no person in any aisle.