Browse Prior Art Database

Dial Micrometer

IP.com Disclosure Number: IPCOM000073628D
Original Publication Date: 1971-Jan-01
Included in the Prior Art Database: 2005-Feb-22
Document File: 2 page(s) / 38K

Publishing Venue

IBM

Related People

Bobar, S: AUTHOR [+3]

Abstract

The interruption of a light beam by a dial micrometer's pointer is reliably detected by a noise-proof circuit. The normal lighted state is maintained by all probe positions except one. The dial pointer blocks the light through the aperture at a point which is predetermined by a selected travel limit or a machine tool workpiece holder. Absence of light increases the photocell internal resistance Rp applying a positive voltage to the amplifier input. Relay contacts K are held normally closed by transistor T in the on state. When the transistor T is made nonconductive by the amplified output of the interrupted light beam, an open circuit is provided by the relay K contacts. Manual control of external system is afforded by closing switch S.

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Dial Micrometer

The interruption of a light beam by a dial micrometer's pointer is reliably detected by a noise-proof circuit. The normal lighted state is maintained by all probe positions except one. The dial pointer blocks the light through the aperture at a point which is predetermined by a selected travel limit or a machine tool workpiece holder. Absence of light increases the photocell internal resistance Rp applying a positive voltage to the amplifier input. Relay contacts K are held normally closed by transistor T in the on state. When the transistor T is made nonconductive by the amplified output of the interrupted light beam, an open circuit is provided by the relay K contacts. Manual control of external system is afforded by closing switch S. Illustratively, Rp is approximately R when lighted and increases to 40R when incident light is blocked. The 2 amplifier input thus changes from a negative voltage to almost +V. If V is chosen to be significantly greater than noise signals, the amplifier is insensitive to the noise. Noise insensitivity is enhanced by selecting C to give an RC time constant significantly longer than noise pulses. Noise signals affect the power supply voltages +V and - V equally, cancelling their effect on the circuit.

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