Temperature control by means of a CCD-camera in welding fiber ribbon cables

• US 6,499,319 B1
• Filed: 06/01/2000
• Issued: 12/31/2002
• Est. Priority Date: 02/14/1997
• Status: Expired due to Term

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Esmaeili, Sasan
• Primary Examiner(s): HOFFMANN, JOHN M
• Application Number:
  US09/584,472
• Time in Patent Office: 943 Days
• Field of Search: 655/01, 654/07, 654/84, 654/88
• US Class Current: 65/484
• CPC Class Codes: G01J 2005/0077 Imaging
• CPC Class Codes: G01J 5/0003 for sensing the radiant heat transfer of samples, e.g. emittance meter
• CPC Class Codes: G01N 21/67 using electric arcs or discharges
• CPC Class Codes: G02B 6/2551 using thermal methods, e.g. fusion welding by arc discharge, laser beam, plasma torch

Abstract

In welding optical fiber ribbons by means of an electric arc formed between electrodes the region heated by the electric arc is mapped on CCD-elements in a camera. In the obtained picture the light intensity of those portions of the picture is determined which correspond to the heated fiber portions. This light intensity is used for setting the electric current flowing between the electrodes, so that a desired welding temperature is obtained and so that also a desired, lower temperature is obtained in the fiber ends in a preparatory softening stage, which has a long durability and which is performed before the very welding stage. This determination of temperatures by means of measured light intensities gives reliable values also in the case where ambient conditions like the air pressure are changed, the state of the electrodes is changed owing to contamination, etc. During the preparatory stage the ends of the individual fibers are deformed, so that they can come in contact with each other, even if the end surfaces of the individual fibers in a fiber ribbon are not located in a plane, which extends in an angle that is exactly perpendicular to the longitudinal direction of the fiber ribbon, and so that mechanical stresses obtained when pressing the fiber ends against each other are relieved.

Claims

1. A device for welding a first optical fiber ribbon to a second optical fiber ribbon, the first and second optical fiber ribbons comprising each a plurality of optical fibers, in the welding operation ends of optical fibers in the first optical fiber ribbon being welded to ends of optical fibers in the second optical fiber ribbon, the device comprising:

electrodes connected to a high-voltage source for forming an electric arc, in which the ends of the optical fibers are heated when an electrode current passes between the electrodes,

retainer and positioning means for placing the optical fibers, so that an end surface of an optical fiber in the first optical fiber ribbon is located opposite and at an end surface of an optical fiber in the second optical fiber ribbon, and

a microprocessor connected to the high voltage source and to the retainer and positioning means, the microprocessor being arranged to control the retainer and positioning means, so that the end surfaces are made to move toward each other from a first position at a small distance of each other to a second position in which an end surface of at least one optical fiber in the first optical fiber ribbon is in contact with an end surface of an optical fiber in the second optical fiber and then to a third position in which the end surfaces of all optical fibers in the first optical fiber ribbon are pressed against end surfaces of optical fibers in the second fiber ribbon with an overlap, and to maintain the end surfaces in the third position during a first time period, and to control the high voltage source to make such electrode currents pass between the electrodes that the ends of the optical fibers during the movement between the first and third positions are maintained at a first temperature during the first time period and at a second temperature equal to or higher than the first temperature during a second time period, the first and second temperatures being sufficiently high in order that the material of the ends of the optical fibers will soften, so that the ends of the optical fibers can be somewhat deformed at the pressing operation of the end surfaces against each other, but not being sufficiently high in order that a melting of or a joining of the ends of opposite optical fibers will take place, and to control the retainer and positioning means to make the first period, during which the end surfaces are being pressed against each other, have such a length as to achieve such deforming of the ends, that elastic stresses in all pairs of opposite end surfaces of the optical fibers are substantially relieved or relaxed, and wherein

the microprocessor being arranged to control the high voltage source, so that the heating of the ends of the optical fibers being then continued at a high temperature, at which a melting and thereby a joining of ends of opposite optical fibers in the first and second optical fiber ribbons takes place.

2. The device of claim 1, wherein the microprocessor is arranged to control the retainer and positioning means to move the end surfaces between the second and third positions with a velocity of the movement lower than a velocity of the movement between the first and second positions.

3. The device of claim 2, wherein the microprocessor is arranged to control the retainer and positioning means to move the end surfaces between the second and third positions with a velocity of the movement substantially equal to half the velocity of the movement between the first and second positions.

4. The device of claim 1, wherein the microprocessor is arranged to control the retainer and positioning means to pull, during a third time period at an end of the second time period or when the ends of the optical fibers have been maintained at the second temperature during a predetermined time period, the ends of opposite optical fibers away from each other through a predetermined, short distance.

5. The device of claim 4, wherein the microprocessor is arranged to control the retainer and-positioning means to move the end surfaces so that the velocity of the movement between the second and third positions is substantially equal to a velocity of the movement used when the end surfaces are pulled away from each other.