Method and apparatus for coating optical waveguide fibers

• US 5,366,527 A
• Filed: 04/05/1993
• Issued: 11/22/1994
• Est. Priority Date: 04/05/1993
• Status: Expired due to Term

• Current Assignee: Corning Incorporated
• Original Assignee: Corning Incorporated
• Inventors: Leoni, Heidi B., Watson, Johnnie E., Chludzinski, Paul A., Williams, Richard R., Amos, Lynn G.
• Primary Examiner(s): LINDSAY JR, ROBERT
• Application Number:
  US08/043,448
• Time in Patent Office: 596 Days
• Field of Search: 65/2, 65/3.11, 65/12, 65/13, 65/29, 65/11.1, 65/3.43, 118/698, 118/667, 118/600, 118/720
• US Class Current: 65/382
• CPC Class Codes: C03C 25/12 General methods of coating; Devices therefor

Abstract

A method and apparatus is provided for controlling the diameter of a coated optical waveguide fiber. The viscosity profile of the coating material is controlled by adjusting the temperature of a portion of the coating assembly based on a measurement of the diameter of the coated fiber. By controlling the viscosity profile of the coating material, the amount of coating applied to the fiber is controlled,, thereby determining the diameter of the coated fiber.

Claims

1. A method for coating an optical waveguide fiber, comprising the steps of

a. passing an optical waveguide fiber through a coating die containing a coating material, said coating material being a curable material, and said coating die including a sizing die,

b. coating said fiber with a layer of said coating material,

c. measuring the coated fiber diameter and generating a diameter signal which is representative of said coated fiber diameter, and

d. controlling the coated fiber diameter by varying the temperature of at lest a portion of said sizing die in response to the difference between said diameter signal and a predetermined target value.

2. The method of claim 1, wherein said controlling step comprises controlling the temperature of an outer wall surface of said sizing die.

3. The method of claim 2, wherein said outer wall surface comprises the bottom surface of said sizing die.

4. The method of claim 1, wherein said coating step comprises applying said coating material as a secondary coating layer over a primary coating layer applied to said optical waveguide fiber.

5. The method of claim 1, wherein the temperature of the coating material is varied such that coated fiber diameter is varied at a rate up to about 0.5 μ

m/sec for a fiber drawing speed of about 15 m/sec.

6. The method of claim 1, wherein said at least a portion of said sizing die comprises a portion of said sizing die wherein the diameter of said sizing die is substantially constant.

7. The method of claim 1, wherein said coated fiber diameter is maintained within about 3 μ

m of said predetermined target value.

8. The method of claim 7, wherein said coated fiber diameter is maintained within about 0.3 μ

m of said predetermined value.

9. An apparatus for coating an optical waveguide fiber, comprising

a. a coater for applying a coating material to the fiber to form a coating layer on the fiber, said coater including a sizing die with a die land region wherein the diameter of said sizing die is substantially constant, and wherein said coating material is a curable material.

b. a curing device for curing said coating layer,

c. a diameter measurement device for measuring the diameter of the fiber including said coating layer and generating a diameter signal representative of said diameter,

d. a heater operatively associated with said die land region, and

e. a controller for varying the heat supplied from said heater to said die land region in response to said diameter signal

10. The apparatus of claim 9, wherein said sizing die includes a bottom surface, and, wherein said heater is operatively associated with said bottom surface of said sizing die.

11. The apparatus of claim 10, wherein said heater further comprises a thermoelectric chip.

12. The apparatus of claim 10, wherein said means for controlling the temperature of a portion of said coating means further comprises

a. a disk of high thermal conductivity material which is in thermal communication with the bottom of said sizing die,

b. a heat transfer tube which is in thermal communication with said disk, and

c. a resistive heater which is in thermal communication with said heat transfer tube,

wherein said disk, said heat transfer tube, and said resistive heater are in thermal communication with said bottom surface of said sizing die.

13. The apparatus of claim 12, further comprising a fluid circulation system which is in thermal communication with said heat transfer tube.

14. An apparatus for coating an optical waveguide fiber, comprising

a. a sizing die with a land region and a bottom surface to which a curable coating material is supplied,

b. means for curing said coating material,

c. means for measuring the diameter of the fiber after the coating material has been applied, and

d. means for heating and sizing die in response to a deviation of a measured coated diameter from a desired value,

said means for heating further comprising means for localized heating in said land region.

15. The apparatus of claim 14, wherein said means for heating further comprises a resistive heater in thermal communication with said bottom surface of said sizing die.

16. The apparatus of claim 14, wherein said means for heating further comprises a thermoelectric chip.

17. A method for controlling a coated diameter of an optical fiber, comprising the steps of

a. introducing the fiber to a coating device, said coating device being supplied with a curable coating material,

b. applying a layer of said curable coating material to the fiber,

c. removing the fiber from the coating device through a sizing die,

d. curing the layer of curable coating material,

e. measuring the coated diameter of the fiber and generating a signal representative of the coated diameter,

f. comparing the signal to a predetermined desired value of the coated fiber diameter, and

g. controlling the coated diameter by locally heating the coating material adjacent to said sizing die to vary the viscosity of the coating material adjacent to the sizing die, thereby varying the coated diameter.