Browse Prior Art Database

Small Increment Positioner

IP.com Disclosure Number: IPCOM000097442D
Original Publication Date: 1962-Dec-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 34K

Publishing Venue

IBM

Related People

Barcia, CL: AUTHOR [+2]

Abstract

This is a device for moving and positioning an element with excursions of 0.1 milli-inches and less with tolerances to within 5%.

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Small Increment Positioner

This is a device for moving and positioning an element with excursions of 0.1 milli-inches and less with tolerances to within 5%.

The device consists of a bearing surface having capillaries in it. Air, from a source of uniform pressure, is applied to these capillaries. This causes a pressurized air film to be formed in the gap between the bearing surface and a fixed thrust plate. An arm passing through the thrust plate has the element to be positioned fixed to it. The air film in the gap is pre-loaded, i.e., the air pressure of the film is externally controlled, electromagnetically. This is either by use of a voice coil arrangement as shown or by a solenoid.

An air film existing between two surfaces exhibits linear spring characteristics within certain ranges of supply pressure and preloading values. With this device, the initial design parameters are such that the air film is operating in the linear spring characteristic region. With voice coil pre-loading as shown, the pre- loading force is directly proportional to the current input. With solenoid pre- loading, this force is proportional (for small magnetic gaps) to the current squared.

Therefore, depending on the nature of the motion desired, either form of pre- loading can be used. Since the spring constant and the moving mass are known, the forcing function required to give any prescribed motion to be followed in an excursion, e.g., maintaining fairly constant velocity for 50%, of...