Patent ID: 8115162

Claim:
A sliding door apparatus comprising: a first door that opens and closes a first entrance by being slid horizontally; a second door that opens and closes a second entrance that faces the first entrance by being slid horizontally together with the first door; imaging means that is disposed beside a space between the first entrance and the second entrance, and that captures images across the space a light emitter that has a vertically long light-emitting surface that is disposed so as to face the imaging means across the space, the imaging means capturing images of the light-emitting surface; and a control apparatus that has an image processing and determining portion that determines presence or absence of an obstruction inside the space based on image data from the imaging means, and that controls opening and closing of the first and second doors depending on presence or absence of an obstruction, the image processing and determining portion using a reference length of an image of the light-emitting surface that corresponds to a position of the first door, and the image processing and determining portion determines that an obstruction is present if an image of the light-emitting surface is discontinuous, if a length of an image of the light-emitting surface becomes shorter, or if an image of the light-emitting surface disappears.