초록 ▼

Apparatus for sensing a missing or broken wafer in an automated wafer transfer system. The apparatus includes means for moving a wafer transfer mechanism from a first position along a prescribed path. A counter coupled to an oscillator is enabled when the wafer transfer mechanism and a wafer are mov

Apparatus for sensing a missing or broken wafer in an automated wafer transfer system. The apparatus includes means for moving a wafer transfer mechanism from a first position along a prescribed path. A counter coupled to an oscillator is enabled when the wafer transfer mechanism and a wafer are moved away from the first position. A photosensor senses the presence of the wafer at a second position along the prescribed path and inhibits the counter. The count stored in the counter is compared with a predetermined count corresponding to the time required for movement of an unbroken wafer to the second position. If the counts do not agree, a missing or broken wafer is indicated and corrective action is taken.

대표청구항 ▼

Apparatus for detecting a condition wherein a wafer in a wafer transfer mechanism is missing or broken, said apparatus comprising: transfer means for moving said wafer from a first position along a prescribed path to a second position; oscillator means; counter means having a count input coupled to

Apparatus for detecting a condition wherein a wafer in a wafer transfer mechanism is missing or broken, said apparatus comprising: transfer means for moving said wafer from a first position along a prescribed path to a second position; oscillator means; counter means having a count input coupled to the output of said oscillator; first sensing means for sensing movement of said transfer means from said first position along said prescribed path and for thereupon enabling said counter means; second sensing means for non-contact sensing of said wafer in said transfer means at an intermediate position along said prescribed path without interrupting the movement of said wafer and for thereupon inhibiting said counter means, said second sensing means comprising a light emitting element having a beam directed laterally across said prescribed path and a photosensor directed laterally across said prescribed path and positioned to receive said beam; and comparator means for comparing the accumulated count in said counter means with a predetermined count representing the presence of a non-broken wafer and for providing an output signal of a first state when the accumulated count equals the predetermined count and of a second state when the accumulated count and the predetermined count are not equal, said second state of said comparator output signal representing said condition wherein said wafer is broken or missing.