US4617173A
Expired / Lapsed
US
⏱️ 0.0 years remaining
System for controlling the diameter of a crystal in a crystal growing furnace
Assignee: SPX Technologies Inc
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Filing: 1984-11-30
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Granted: 1986-10-14
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Expires: 2004-11-30
Abstract
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.
Inventors
- 👤 Henry C. Latka
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 16:15
CPC Classifications
C; C30; C30B; C30B15/00; C30B15/20; C30B15/22; C30B15/26; Y; Y10; Y10T; Y10T117/00; Y10T117/10; Y10T117/1004; Y10T117/1008
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
196 words
A system for controlling the diameter of a crystal in a crystal growing furnace having an angle transducer connected to a crystal diameter scaling and control means which is in turn connected to rod and crucible lift and rotation mechanisms, a crucible containing a melt, and crystal diameter scaling and control means comprising; (a) transducer and servo motor means disposed above a furnace having respective shafts connected along a common axis on opposite sides of a longitunal light tube respectively wherein the light tube and transducer shaft can be angularly positioned by the shaft of the servo motor, (b) the light tube having a lens for focusing on a spot on a meniscus in the furnace and at times on the melt, (c) light sense detecting and tracking means for at times generating a servo motor control error signal to drive the servo motor to an angular position corresponding to growth in diameter of the meniscus by angularly tracking a spot of light on the meniscus, and (d) crystal diameter sensing means governed by a signal from the transducer indicative of the angular position of the light tube when tracking a light spot on the meniscus.
Claim 2
Independent Claim
196 words
A system for controlling the diameter of a crystal in a crystal growing furnace having an angle transducer connected to a crystal diameter scaling and control means which is in turn connected to rod and crucible lift and rotation mechanisms, a crucible containing a melt, and crystal diameter scaling and control means comprising; (a) transducer and servo motor means disposed above a furnace having respective shafts connected along a common axis on opposite sides of a longitunal light tube respectively wherein the light tube and transducer shaft can be angularly positioned by the shaft of the servo motor, (b) the light tube having a lens for focusing on a spot on a meniscus in the furnace and at times on the melt, (c) light sense detecting and tracking means for at times generating a servo motor control error signal to drive the servo motor to an angular position corresponding to growth in diameter of the meniscus by angularly tracking a spot of light on the meniscus, and (d) crystal diameter sensing means governed by a signal from the transducer indicative of the angular position of the light tube when tracking a light spot on the meniscus.
Claim 3
Dependent Claim
47 words
A system for controlling the diameter of a crystal in a crystal growing furnace according to claim 1 wherein the angular transducer generates linear output signals for incrementally sensing changes in crystal diameter, thus limiting overcorrection due to intermittent diameter changes caused by orbiting of a crystal.
Claim 4
Dependent Claim
45 words
A system for controlling the diameter of a crystal according to claim 2 wherein a threshold detector is provided for obtaining close loop operation of the servo motor, thus causing the angularly positioned light tube to follow a certain reflected light level from the meniscus.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1989-10-13 | 1990-04-14 | 1990-10-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-10-13 | 1994-04-14 | 1994-10-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-10-13 | 1998-04-14 | 1998-10-14 | $7700.00 | Window Closed / Lapsed |