US 3,941,332 AGranted

Rotational position sensor

AssigneeBell & Howell Company

InventorJerry Matula

Life of this patent

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Abstract

A rotational position sensor is disclosed in which the beam from a light emitting diode mounted on a rotatable element is directed onto a pair of adjacent photocells. The portion of the beam falling upon each of the photocells determines the photocell output signal. The output signals are combined to form a signal which varies generally linearly with the rotational position of the element upon which the light emitting diode is mounted. The photocells are disposed in relatively close relation to one another, and the light emitting diode is disposed relatively close to each of the photocells and a short distance from the axis of rotation of the element. By use of appropriate masks the size of the beam from the light emitting diode can be varied so as to provide linear response over varying angular ranges of movement of the rotatable element.

Claims2

Dependent claims

A motion picture camera having a rotational position sensor comprising:

a light emitting diode;
first means mounting the light emitting diode substantially at an axis of rotation for movement about the axis of rotation;
a pair of generally planar photoelectric cells disposed within a common plane which is generally parallel to the axis of rotation and spaced therefrom by a distance substantially greater than any distance between the diode and the axis of rotation and the distance between the photoelectric cells, the photoelectric cells being operative to generate varying output signals in accordance with the amount of light from the light emitting diode incident thereon as the light emitting diode undergoes movement about the axis of rotation;
and
the first means includes a tension arm mounted for rotation about the axis of rotation and having the light emitting diode mounted thereon, the tension arm comprises part of the motion picture camera having a reel for supplying and taking up motion picture film and a servo system including a motor for driving the reel in accordance with the output signals from the photoelectric cells.

2 more elements

Dependencies are inferred from the claim text.

Facts

Application: 05/493,183Filed 30 Jul 1974 · division
Priority: 12 Feb 1973
Granted: 2 Mar 1976
Term ends: Not estimatedThe source records don’t support an estimate.

Classification6 codes

G01D 5/30
With deflection of beams of light, e.g. for direct optical indication: the beams of light being detected by photocells
G03B 1/54
Guiding, framing, or constraining film in desired position relative to lens system: tensioning or loop-maintaining devices
G11B 15/43
Driving; Starting; Stopping; Arrangements for control or regulation thereof: control or regulation of mechanical tension of record carrier, e.g.…
G01D
Measuring not specially adapted for a specific variable