Curved lamp manufacturing method, curved lamp, and backlight unit

Abstract

A curved lamp manufacturing method including a curving process in which a straight glass tube sealed with reduced pressure inside is heated and curved. The curving process includes: a first step of holding a predetermined portion of the glass tube using a first chuck, and holding one end portion of the glass tube using a second chuck such that the second chuck can slide in a longitudinal direction of the glass tube; and a second step of, while heating a planned curved portion of the glass tube positioned between the predetermined portion and the end portion by a heater, curving the planned curved portion by moving the second chuck relative to the glass tube. The end portion is moved in the second step so that a weight of the end portion is applied to the planned curved portion that has been softened by the heater.

1 . A curved lamp manufacturing method including a curving process in which a straight glass tube, which was sealed with inside thereof being under reduced pressure, is heated and curved,
 the curving process comprising:   a first step of holding a predetermined portion of the straight glass tube using a first chuck, and holding one end portion of the straight glass tube using a second chuck in a manner that the second chuck can slide in a longitudinal direction of the straight glass tube; and   a second step of, while heating by a heater a planned curved portion of the straight glass tube, which is positioned between the predetermined portion and the end portion, curving the planned curved portion by moving the second chuck relative to the straight glass tube, wherein   the end portion is moved in the second step so that a weight of the end portion is applied to the planned curved portion that has been softened by heat of the heater.   
   
   
       2 . The curved lamp manufacturing method of  claim 1 , wherein
 in the second step, the second chuck is rotated by a predetermined amount of angle around a center of curvature of a curved portion of a glass tube generated by curving the straight glass tube, a trajectory thereof drawing an arc.   
   
   
       3 . The curved lamp manufacturing method of  claim 2 , wherein
 in the first step, the straight glass tube is held so as to extend in a substantially horizontal direction, and   in the second step, the second chuck is rotated upward by substantially 90 degrees along a vertical plane that includes a tube axis of the glass tube.   
   
   
       4 . The curved lamp manufacturing method of  claim 1 , wherein
 in the second step, the heater and the second chuck are simultaneously moved so that a heating position of the glass tube heated by the heater moves in a same direction as the second chuck.   
   
   
       5 . The curved lamp manufacturing method of  claim 3 , wherein
 in the first step, another end portion of the straight glass tube, which is across the predetermined portion from the end portion, is further held using a third chuck in a manner that the third chuck can slide in the longitudinal direction of the straight glass tube, and   in the second step, another planned curved portion of the straight glass tube, which is positioned between the predetermined portion and the other end portion, is further heated by another heater, the other planned curved portion is curved by moving the third chuck relative to the straight glass tube, and a weight of the other end portion is applied to the other planned curved portion that has been softened by heat of the heater, wherein the second and third chucks are rotated so that trajectories thereof substantially produce a plane symmetry on either side of a plane that is perpendicular to the tube axis of the straight glass tube at a center of the predetermined portion.   
   
   
       6 . The curved lamp manufacturing method of  claim 5 , wherein
 in the second step, the heater and the second chuck are simultaneously rotated so that a heating position of the glass tube heated by the heater moves in a same direction as the second chuck, and the other heater and the third chuck are simultaneously rotated so that a heating position of the glass tube heated by the other heater moves in a same direction as the third chuck.   
   
   
       7 . The curved lamp manufacturing method of  claim 1 , wherein
 a sheath heater is used as the heater, the sheath heater is disposed at the planned curved portion, and the planned curved portion is locally heated by the sheath heater.   
   
   
       8 . The curved lamp manufacturing method of  claim 7 , wherein
 the sheath heater is in a shape of a coil that is formed by winding a heater wire, and   the curving process further comprises   a step of letting the straight glass tube pass through the coil of the sheath heater so that the planned curved portion is positioned at the coil of the sheath heater.   
   
   
       9 . The curved lamp manufacturing method of  claim 8 , wherein
 adjacent turns of the heater wire in the coil are in contact with each other.   
   
   
       10 . The curved lamp manufacturing method of  claim 8 , wherein
 the coil has three turns of the heater wire.   
   
   
       11 . The curved lamp manufacturing method of  claim 7 , wherein
 the sheath heater has been formed by bending the heater wire into a shape of a cylinder whose side has an opening, and   the curving process comprises   a step of inserting the planned curved portion of the straight glass tube through the opening into the sheath heater.   
   
   
       12 . The curved lamp manufacturing method of  claim 11 , wherein
 the sheath heater in the shape of a cylinder whose side has an opening, when viewed from top of the cylinder, is in a shape of character C or U or a concave.   
   
   
       13 . The curved lamp manufacturing method of  claim 1  further including:
 a removing chuck arrangement process of arranging a removing chuck so that straight tube portions of a glass tube, which was generated by curving the straight glass tube in the curving process, is placed between a first member and a second member of the removing chuck, wherein in the removing chuck, the first member is attached to a first base, the second member is attached to a second base to face the first member, and at least one of the first member and the second member can be inclined against a plane perpendicular to a direction in which the first base and the second base move relatively to each other; and   a glass tube removing process of bringing the first base and the second base relatively close to each other, causing the first member and the second member to sandwich and hold the straight tube portions of the glass tube, and moving the removing chuck in a predetermined direction while the first member and the second member hold the straight tube portions.   
   
   
       14 . The curved lamp manufacturing method of  claim 13 , wherein
 the at least one of the first member and the second member can be inclined to be in contact with the straight tube portions of the glass tube.   
   
   
       15 .- 18 . (canceled)