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Velocity Measuring Device

IP.com Disclosure Number: IPCOM000075957D
Original Publication Date: 1971-Dec-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 2 page(s) / 37K

Publishing Venue

IBM

Related People

Thomas, DC: AUTHOR

Abstract

Described is a device which is capable of measuring the velocity of a rotating shaft or variations in the velocity of a rotating shaft. It is also suitable for measuring linear velocities, when modified, as will be pointed out hereinafter. The unit includes a slit-light source positioned in spaced relationship to a photocell. An exposed photographic negative having a calibrated gray scale, circumferentially disposed thereabout, is attached to a rotating shaft and positioned between the slit-light source and the photocell. A time base calibrated scope, not shown, is connected to the output from the photocell. As the photographic negative rotates, it modulates the intensity of the light seen by the photocell and thus the trace on the calibrated scope. Fig.

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Velocity Measuring Device

Described is a device which is capable of measuring the velocity of a rotating shaft or variations in the velocity of a rotating shaft. It is also suitable for measuring linear velocities, when modified, as will be pointed out hereinafter. The unit includes a slit-light source positioned in spaced relationship to a photocell. An exposed photographic negative having a calibrated gray scale, circumferentially disposed thereabout, is attached to a rotating shaft and positioned between the slit-light source and the photocell. A time base calibrated scope, not shown, is connected to the output from the photocell. As the photographic negative rotates, it modulates the intensity of the light seen by the photocell and thus the trace on the calibrated scope. Fig. 2 shows the pattern displayed for a uniformly rotating shaft; that is, no accelerations or decelerations. The slope of the trace will be determined by the actual velocity of the shaft and is a measure of that velocity. Fig. 3 shows the effect of a decrease in velocity at a specific angular position during successive rotations of the shaft. If linear motion is to be detected, the gray scale would be arranged in a linear fashion and would function in the same way. The principal advantage of this system for measuring velocity is that it has no physical contacts and thus no friction is introduced, which would have an effect on the velocity of the shaft or other device being measured. The pho...