Robust belt tracking and control system for hostile environment
US6126512A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 10, 1998 |
| Grant date | Oct 3, 2000 |
| Priority date | — |
| Expiry date | Jul 10, 2018 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB24B21/20
- WIPO fieldMachine tools
- WIPO sectorMechanical engineering
Abstract
An automated tracking and control system measures the lateral displacement of a moving belt, using non-contact sensing. The displacement signal is provided to an algorithm that adjusts the tilts of the belt pulleys and steers the belt laterally. Non-contact sensors include inductive proximity sensors, which respond to the metal belt but are immune to airborne slurry and other non-metallic debris in a hostile environment typical of wafer polishing. Other non-contact sensors include shielded optical sensors. Dual sensor configurations cancel response to non-lateral displacements. Instrumentation, such as tension sensors, cylinder pressure sensors, load transducers, and limit switches, provides input to the algorithm. Independent tension signals for each belt edge verify proper functioning of, e.g., pad conditioners. User-specified belt displacements, e.g., dither, sawtooth oscillation, step, ramp, and sweep, combine with selective texturing and other variable pad properties to provide a desired polishing rate profile.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.