Abstract: This disclosure relates to an object detector which incorporates a photoelectric detector in the vacuum flow path of a vacuum pickup system to serve as a device to determine whether an object has been successfully engaged, retained and transported by a vacuum orifice, so that transport cycles may be modified or terminated by control circuitry in the event that the object has not been successfully engaged, retained and transported, thereby saving time and reducing damage to object, transport means or the surface to which the object is transported.

Abstract: A bidirectional stepping motor drive circuit receives stepping pulses and a directional control signal. A binary up/down counter counts the stepping pulses in an up or down direction depending on the state of the directional control signal. A BCD to decimal decoder has inputs coupled to the counter and generates selected outputs in response to selected states of the counter. Logic means responds to the selected outputs and generates phase voltage pulses during which current is supplied to the motor coils. A high voltage starting pulse is applied at the beginning of each stepping cycle to establish the coil current.

Abstract: This disclosure relates to an object transport apparatus particularly useful for the high speed handling of semiconductor chips. Transport is achieved by driving a vacuum pickup, through a rotational motion toward an object resting at a first reference location while simultaneously driving a cam, restraining a spring loaded cam follower, so that the vacuum pickup is positioned proximal to the first reference position. Vacuum is applied to secure the object to the pickup. The cam and shaft are then simultaneously driven in the opposite direction to clear the other objects and obstruction by swinging the object through an arcuate motion while simultaneously elevating the object. As the pickup and object continue through the arcuate motion, the cam motion is reversed to position the object proximal to a deposition surface located at a second reference position. The cam is then further driven to contact the object with the deposition surface, the vacuum is released and the object is released.