US 2002/0059014 A1 · Sensing head positioning system using two-stage offset air bearings

Abstract

A system is provided wherein a plurality of high accuracy air injectors are disposed along the edges of a sensor plate of a sensing head to form an air bearing and a plurality of high displacement air injectors are also disposed along the edges of the sensor plate to form an air bearing, each independently controlled, with the sensing head having high accuracy and low accuracy separation distance sensors coupled in a feedback loop through a mapper (a programmable CPU) which, without knowledge of the exact position of the sensors or air injectors, but being responsive to feedback information, iteratively adjusts relative separation of the sensor plate and a flat panel workpiece to the desired positional accuracy through digital to analog converters supplying control signals to analog amplifiers controlling orifices. Translation is effected after the high displacement air injectors are activated, with the combination of flow of air from the air bearing outlets along the edge of the sensor plate and the translation in x and y of the flat panel being operative to air brush sweep the surface of the flat panel.

Claims27

Dependent claims

An apparatus for positioning a sensing head relative to a workpiece, the apparatus comprising:

a control unit operative to provide a plurality of control signals to iteratively control positioning of the sensing head relative to the workpiece;
a plurality of air injectors disposed and fixedly connected on the periphery of the sensing head, the air injectors receiving the control signals and ejecting a gas between the sensing head and the workpiece to create an air bearing and affect positioning of the sensing head relative to the workpiece in response to the control signals;
and
a plurality of sensors providing a plurality of feedback signals to the control unit, the feedback signals containing information relating to positioning of the optical imaging sensing head relative to the workpiece.

1 more element

An apparatus for positioning a sensing head relative to a workpiece, the apparatus comprising:

a plurality of sensors operative to detect a reading of positioning of the sensing head relative to the workpiece;
a plurality of air injectors fixedly connected with the sensing head, each of the air injectors capable of ejecting a gas with a variably controllable output level between the sensing head and the workpiece in order to affect positioning of the sensing head relative to the workpiece;
and
a control unit operative to receive the reading from the sensors and to control the air injectors, the control unit being capable of locating the sensing head relative to the workpiece within a desired range, said locating comprising:
(a) varying the output level of each air injector by a small amount and noting a resulting change in the reading received from the sensors in order to form an output-to-movement relationship;
(b) applying an inverse of the output-to-movement relationship to the reading received from the sensors in order to calculate a plurality of output adjustments;
(c) adjusting the output levels of the air injectors by the output adjustments;
and
(d) repeating (a) through (c) until positioning of the sensing head relative to the workpiece is within the desired range.

6 more elements

Dependencies are inferred from the claim text.

Sensing head positioning system using two-stage offset air bearings

Life of this patent

Sensing head positioning system using two-stage offset air bearings

Life of this patent

Abstract

Claims27