Patent ID: 7574934

Claim:
A missing hole detector to detect a missing or misplaced hole in a workpiece under test, said missing hole detector comprising: an end surface to which a pushing force is applied; a test probe to be moved towards the workpiece under test in response to the pushing force applied to said end surface; a switching circuit responsive to the movement of said test probe toward the workpiece under test, said switching circuit including a first switch having an open switch position when said test probe is moved into the hole and penetrates the workpiece under test in response to the pushing force being applied to said end surface, whereby said switching circuit has a first circuit condition, said first switch having a closed switch position when said test probe is moved into contact with and fails to penetrate the workpiece under test because a hole is absent, whereby said switching circuit has a second circuit condition; a first cam having first and second cam surfaces and moving with said test probe relative to said first switch towards the workpiece under test in response to the pushing force applied to said end surface, said first switch having a switch arm that communicates with the first cam surface of said first cam when said test probe is moved into the hole and penetrates the workpiece to cause said first switch to have said open switch position and said switching circuit to have said first circuit condition, the switch arm of said first switch communicating with the second cam surface of said first cam when said test probe fails to penetrate the workpiece because a hole is absent to cause said first switch to have said closed switch position and said switching circuit to have said second circuit condition; and a transmitter communicating with said switching circuit and adapted to transmit an output signal when the switching circuit is in the second circuit condition to indicate that the test probe has failed to enter a hole and penetrate the workpiece.