Article shelf

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.