Coating processes – Measuring – testing – or indicating
Patent
1997-06-06
1999-11-02
Edwards, Laura
Coating processes
Measuring, testing, or indicating
4271632, 4274346, 4274347, 118665, 118667, 118683, 118684, 118688, 118692, 118708, 118712, 118405, 118411, 118412, 118420, B05D 100
Patent
active
059766115
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an optical fiber coating method and apparatus therefor, which can form a high quality coating layer on an optical fiber which is drawn at high speed.
2. Description of the Related Art
An optical fiber drawn from a drawing furnace is normally provided a primary coating to be a buffer layer with an ultraviolet curing resin, silicon resin or the like, before contacting with a solid substance, such as a take-up roller. Furthermore, a secondary coating layer for reinforcement is provided with an ultraviolet curing resin, nylon or the like.
As such conventional optical fiber coating apparatus, the apparatus disclosed in Japanese Patent Application Publication No. 2-25854 (1990), Japanese Patent Application Laid-Open No. 61-72656 (1986), Japanese Patent Application Publication No. 5-37938 (1993), Japanese Patent Application Laid Open No. 64-65430 (1989), for example, have been known.
The apparatus disclosed in Japanese Patent Application Publication No. 2-25854 detects a center position of an optical fiber drawn from a drawing furnace by means of a measuring unit. Then, the overall coating apparatus is shifted along a plane perpendicular to an axis of the optical fiber by means of a motor so that it may be aligned with the optical fiber coaxially. Thereby, the coating layer of uniform thickness is formed on the optical fiber.
The apparatus disclosed in Japanese Patent Application Laid-Open No. 61-72656 measures an external diameter of the optical fiber with a coating resin layer after passing through a coating die set by an external diameter measuring device. On the basis of the measured value, a supplying pressure of a resin supplied in the coating die set is controlled. Thereby, the optical fiber having a coating layer of uniform external diameter can be obtained.
The apparatus disclosed in Japanese Patent Application Publication No. 5-37938 detects concentricity of a coating resin layer applied by a coating application device with respect to the optical fiber by means of a monitoring device. On the basis of result of detection, the coating application device is inclined about an orthogonal two axes (these two axes are located on a plane perpendicular to the axis of the optical fiber) taking a lower side outlet orifice of the coating application device as a center. Thereby, non-concentricity of the coating resin layer with respect to the optical fiber can be restricted.
In the apparatus disclosed in Japanese Patent Application Laid-Open No. 64-65430, the optical fiber on which the primary coating resin in an upper tank have been supplied, is guided in a pool of a secondary coating resin which is supplied into the lower tank. Then, a transmitted illumination light is projected to the optical fiber to detect the non-concentricity of the primary coating resin layer. On the basis of this, the position of the upper tank relative to the optical fiber is corrected so as to reduce magnitude of non-concentricity.
If the thickness of the primary coating layer or the secondary coating layer formed on the optical fiber is non-uniform, a microbending phenomenon due to variation of ambient temperature, external force applied on the optical fiber or the like, namely, irregular bending, may be caused on the optical fiber resulting in increase transmission loss of the optical fiber. Also, when the thickness of the primary coating layer or the secondary coating layer is non-uniform, strength at the portion where the coating layer is thin, becomes relatively low to increase tendency to snap at such portion. Furthermore, if a bubble is admixed in the coating resin layer, the strength of the optical fiber at such portion becomes relatively low. In addition, since the volume of the bubble varies depending upon variation of the ambient temperature, the foregoing microbending phenomenon is caused to increasing transmission loss of the optical fiber.
Recently, as optical fiber preform have expanded in length, drawing speed is becoming higher. When t
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patent: 4577588 (1986-03-01), Mautret et al.
patent: 4631078 (1986-12-01), Tomlinson et al.
patent: 4740055 (1988-04-01), Kanda et al.
patent: 5047386 (1991-09-01), Hed
Inoue Akira
Kobayashi Kohei
Oishi Kazumasa
Okuno Kaoru
Tsuchiya Ichiro
Edwards Laura
Sumitomo Electric Industries Ltd.
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