Patent ID: 7027894

Claim:
An apparatus for transporting articles, the apparatus comprising: a body, and a mechanism for picking up an article, holding the article proximate to the body when the body moves to transport the article, and releasing the article; a thru-beam sensor attached to the body, wherein the thru-beam senor's beam is broken when the article held by the apparatus is thicker than a first predetermined amount, but the beam is not broken when the article held by the apparatus is thinner than a second predetermined amount which is less than or equal to the first predetermined amount, wherein when the apparatus is not holding the article and the beam is not broken, then the beam becomes broken by an article to be picked up when the body is approaching the article to be picked up, and wherein when the apparatus is holding an article thinner than the second predetermined amount and the beam is not broken, the beam becomes broken when the body is approaching a surface at which the article is to be released; circuitry for receiving a signal indicating if the beam is broken, and generating: a signal indicating that the apparatus is holding an article thicker than the first predetermined amount when the apparatus is holding an article and the beam is broken; a signal indicating that the apparatus is holding an article thinner than the second predetermined amount when the apparatus is holding an article and the beam is not broken; a signal indicating that the body is approaching an article to be picked up when the apparatus is not holding an article and the beam becomes broke; and a signal indicating that the body is approaching a surface at which an article is to be released when the apparatus is holding an article thinner than the second predetermined amount and the beam becomes broken.