Article shelf
To prevent two frontages from being simultaneously opened on lower sides thereof, a rack includes a shelf, a first frontage, a second frontage, and a shutter. The shelf can hold an article at a position spaced from a floor surface. The first and second frontages face each other to access to the shelf. The shutter opens one of the two frontages and closes the other. When moving to switch the frontage to be closed, the shutter passes through a space between the floor surface and the shelf.
1 . An article shelf comprising:
a shelf to hold an article at a position spaced from a floor surface;
two frontages facing each other in a direction perpendicular to a width direction of the shelf to provide access to the shelf;
a shutter to open one of the two frontages and to close the other; and
two sensors side by side along a movement path of the shutter, to detect the shutter; wherein
the movement path of the shutter defines a loop such that the shutter is circularly movable;
when moving to switch the frontage to be closed, the shutter passes through a space between the floor surface and the shelf,
the shutter has a length corresponding to a sum of a height of one of the frontages and a length of the shelf in the direction perpendicular to the width direction,
the sensors are in a vicinity of one of the frontages, and when the shutter is detected by one of the two sensors, the shutter closes one of the two frontages,
the shutter continues to move if both the two sensors detect the shutter, and the shutter stops if one of the two sensors does not detect the shutter, and
if a state of the shutter cannot be recognized using the sensors, the state of the shutter is recognized by circularly moving the shutter to cause the sensors to detect the shutter.
2 . The article shelf according to claim 1 , further comprising a drive assembly including a pair of drivers positioned with an interval therebetween, the interval being larger than a width of the shelf, to move the shutter while supporting opposite end portions of the shutter; wherein
each of the drivers includes four rotating structures at four corners along a movement path of the shutter, and an endless structure wrapped around the four rotating structures, to support one of the opposite end portions of the shutter.
3 . The article shelf according to claim 2 , wherein the drive assembly is operable to rotate one of the four rotating structures of one of the pair of drivers, to move the shutter.
4 . The article shelf according to claim 1 , wherein
the shutter continues to move if both the two sensors detect the shutter; and
the shutter stops if one of the two sensors does not detect the shutter.
5 . The article shelf according to claim 1 , further comprising a third sensor side by side the two sensors along the movement path of the shutter, to detect the shutter.
6 . The article shelf according to claim 4 , wherein
it is determined whether or not to stop the shutter if one of the two sensors does not detect the shutter, based on a movement direction of the shutter.
7 . The article shelf according to claim 5 , wherein
it is determined whether or not to decrease the moving speed of the shutter or to stop the shutter if the shutter becomes undetected by one of the three sensors, based on the movement direction of the shutter.