System for controlling the diameter of a crystal in a crystal growing furnace
US4617173A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Nov 30, 1984 |
| Grant date | Oct 14, 1986 |
| Priority date | — |
| Expiry date | Nov 30, 2004 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T117/1008
- WIPO fieldSurface technology, coating
- WIPO sectorChemistry
Abstract
A crystal growing furnace has lift and rotation control apparatus for both a growing crystal and a crucible containing a melt. A transducer and a servo motor are disposed above the furnace having respective shafts connected along a common horizontal axis on opposite sides of a longitudinal light tube wherein the light tube and transducer shaft can be axially positioned by the shaft of the servo motor. The light tube has a lens for focusing at times on a spot on a meniscus in the furnace and at times on the melt, a light sense detector is connected to the light tube for at times generating a servo motor control error signal to drive the servo motor incrementally to an angular position corresponding to growth in the diameter of the meniscus by tracking a spot on the meniscus. The transducer generates an output signal indicative of incremental angular movement in response to growing the crystal for governing the lift and rotation control apparatus.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.