Browse Prior Art Database

Positioning Device

IP.com Disclosure Number: IPCOM000097430D
Original Publication Date: 1962-Nov-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 28K

IBM

Abstract

This device positions an element at any one of a plurality of discrete positions. It maintains the element at the selected discrete position against a tendency of the element to drift away.

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Positioning Device

This device positions an element at any one of a plurality of discrete positions. It maintains the element at the selected discrete position against a tendency of the element to drift away.

The element is a lens which is to be positioned to read one of a plurality of tracks on a rotating photographic disc. Once the lens is positioned over a selected track, it is desired to maintain the lens over that track against a tendency of the lens to drift. The lens is moved to the left or the right in the X plane by applying a current of suitable polarity to a drive coil. This is attached to the lens through a lens arm. The primary coil of a transformer is fixed to the lens arm and moves with it. A potential V(s) developed across the primary coil of the transformer induces a voltage V(1) in the secondary coil. The potential V(1) (voltage diagram) varies linearly with the position of the primary coil and, therefore, of the lens.

Potential V(1) is applied as one input to a comparison circuit.

The other input to this comparison circuit is a reference potential V(r) which is tapped off of a variable resistance element. When V(1) and V(r) are equal, there is no output from the comparison circuit. When V(1) is greater than V(r), there is an output V(d) from the comparison circuit of one polarity. When V(r) is greater than V(1), there is an output from the the comparison circuit of the opposite polarity. The voltage V(d) is converted into a D.C. signal to be ap...