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Browse Prior Art Database

Speed Detection by Phase Shift Check

IP.com Disclosure Number: IPCOM000091864D
Original Publication Date: 1968-Jun-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 56K

Publishing Venue

IBM

Related People

Papadakis, IE: AUTHOR [+2]

Abstract

The phase shift characteristics of a second-order transfer function and a very small damping factor increase the sensitivity of a speed detecting circuit for disk files, etc. Electromagnetic transducer 10 produces a train of pulses 12 proportional to the rotational speed of a disk file or the like. Pulse train 12 is applied to circuitry which lights indicator lamp 14 at or very near a predetermined normal operating speed. The current flowing through lamp 14 can also be used to control safety circuit or the like.

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Speed Detection by Phase Shift Check

The phase shift characteristics of a second-order transfer function and a very small damping factor increase the sensitivity of a speed detecting circuit for disk files, etc. Electromagnetic transducer 10 produces a train of pulses 12 proportional to the rotational speed of a disk file or the like. Pulse train 12 is applied to circuitry which lights indicator lamp 14 at or very near a predetermined normal operating speed. The current flowing through lamp 14 can also be used to control safety circuit or the like.

Pulse train 12 is conveyed through translating circuit 16 having emitter- follower output circuitry providing suitable impedances for matching transducer 10 to the succeeding circuitry and paraphrase output voltages. Both phases are applied to wave shaper 20 which delivers gating pulse wave 22 to gating transistor 26.

One phase of circuit 16 is applied to an emitter-follower transistor 28. Transfer circuit 30, comprising capacitor 32 and inductor 34, converts pulse wave 12 to the form of wave 36. This is applied to level detecting circuit 40 followed by a buffer and an amplifier forwarding waveform 42 to the base of output transistor 44. At the collector of transistor 44, waveform 46 is produced for application to transistor 26. Lamp driving transistor 50 is coupled to transistor 26 to light lamp 14 for a narrow range of speeds centered about the normal operating speed.

The range of speed for which lamp 14 is lighted is narrowed by transfer circuit 30. The undamped natural angular frequency ome...