Injection mold for light guide body and apparatus for manufacturing light guide body using same
View Patent ↗A cavity is defined inside an injection mold to provide a contour of a light guide body. Also provided in the injection mold is a through hole communicating with the cavity and allowing an optical fiber to be inserted in the through hole. The through hole includes a columnar space provided in at least a portion contiguous to the cavity. The columnar space has a predetermined length and a cross section similar to that of the optical fiber, and a clearance left between the columnar space and the optical fiber when the optical fiber is inserted in the through hole is 30 μm or less.
1. An injection mold for a light guide body, comprising:
a cavity defined inside the injection mold to provide a contour of the light guide body; and
a plurality of through holes each of which communicates with the cavity and allows an optical fiber to be inserted in the through hole, wherein each through hole includes a columnar space provided in at least a portion contiguous to the cavity, the columnar space having a predetermined length and a cross section similar to that of the optical fiber and a clearance left between the columnar space and the optical fiber when the optical fiber is inserted in the through hole is 30 μm or less,
wherein the injection mold is comprised of a first mold and a second mold having a first groove and a second groove for each through hole, respectively, which first and second grooves are adapted to mate and form the through hole when the first and second molds are joined together for injection molding with the optical fiber clamped at a portion of the through hole between the first and second grooves, and at least one of opposed portions in the first and second grooves corresponding to the portion of at least one of the through holes at which the optical fiber is clamped is made of an elastic material.
2. An injection mold according to claim 1 , wherein a modulus of elasticity of the elastic material is lower than that of the optical fiber.
3. An injection mold according to claim 1 , wherein a bulk modulus of elasticity of the elastic material is in a range of 0.01×10 10 to 0.40×10 10 Pa.
4. An injection mold according to claim 1 , wherein the elastic material is made of a hard rubber.
5. An injection mold according to claim 1 , wherein the first and second grooves for at least one of the through holes are each shaped to have a curved cross section having a curvature smaller than that of the cross section of the optical fiber.
6. An injection mold according to claim 1 , wherein a sum of depths of the first and second grooves for at least one of the through holes is lesser than a diameter of the cross section of the optical fiber, the sum of the depths being determined in accordance with a modulus of elasticity of the elastic material.
7. An injection mold according to claim 1 , wherein a portion of at least one of the through holes at which the optical fiber is clamped has a cross section such that a diameter of a largest inscribed circle thereof is lesser than a diameter of the cross section of the optical fiber and an area thereof is greater than an area of the cross section of the optical fiber.
8. An injection mold according to claim 1 , wherein the elastic material is a V-shaped telescopic leaf spring.
9. An injection mold according to claim 1 , wherein at least one of the through holes is shaped to have a rectangular cross section.
10. An injection mold according to claim 1 , wherein the clearance left between the columnar space and the optical fiber when the optical fiber is inserted in the through hole is 20 μm or more.
11. An apparatus for manufacturing a light guide body, comprising:
an injection mold according to claim 1 ; and
an injection device to supply a molten material into the cavity.
12. The injection mold for a light guide body according to claim 1 , wherein the portion contiguous to the cavity is a portion of the through holes that is nearest to the cavity.