JP2018205651A - Light guide with heat-resistant incoming part - Google Patents

Abstract

To protect an incoming part of a transparent material from heat generation of a semiconductor light source without lowering light distribution efficiency.SOLUTION: A light guide 11 of a lighting fixture for vehicle comprises a transparent material 12 guiding light that a semiconductor light source 3 generated. The transparent material 12 includes an incoming part 13 entering light emitting of the semiconductor light source 3 and a protect part 16 protecting the incoming part 13 from heat generation of the semiconductor light source 3. The incoming part 13 is formed with a first transparent material, and the protect part 16 is formed with a second transparent material that the softening point is higher than the first transparent material. Acryl or polycarbonate resin is used as the first transparent material, and glass is used as the second transparent material. Otherwise acryl resin is used as the first transparent material, and polycarbonate resin is used as the second transparent material.SELECTED DRAWING: Figure 2

Description

The present invention relates to a light guide that guides light emitted from a semiconductor light source by a light guide, and more particularly to a technique for protecting an incident portion of a light guide from heat generated by a semiconductor light source.

This type of light guide is widely used in indirect illumination in a vehicular lamp using a semiconductor light emitting element such as an LED or LD as a light source. For example, in the vehicular lamp 1 shown in FIG. 8A, the light guide 11 includes a rod-shaped light guide 12 made of a transparent resin, and the incident portion 13 of the light guide 12 is connected to the semiconductor light source 3 on the light source unit 2. Opposing to each other, the light emitting portion 14 of the light guide 12 is provided so as to extend along the inner surface of the front cover 4.

As shown in FIG. 8B, the incident portion 13 normally covers a position approaching the semiconductor light source 3 (preferably, the light distribution angle θ so that the light flux generated by the semiconductor light source 3 can be efficiently distributed. Position). For this reason, when the semiconductor light source 3 is turned on, the end face 15 of the light guide 12 may be softened and deformed by heat generated by light emission. In particular, in recent years, there is a tendency that heat loss is likely to occur in the incident portion 13 as the brightness of the semiconductor light emitting element increases.

Thus, conventionally, a technique for improving the heat resistance of the light guide incident portion has been proposed. For example, in Patent Document 1, as shown in FIG. 9, the entire holder 54 that holds the incident portion 53 of the light guide 52 is molded with a transparent heat-resistant resin material having a softening point higher than that of the incident portion 53. There has been proposed a light guide 51 in which a part of the holder 54 located between the end face 55 of the light guide 52 and the semiconductor light source 56 functions as a heat insulating portion 57.

Japanese Patent Laying-Open No. 2014-4705

However, according to the conventional light guide 51, since the heat insulating portion 57 needs to be arranged away from the semiconductor light source 56 even if it is made of heat resistant resin, it is between the end surface 55 of the light guide 52 and the semiconductor light source 56. The distance becomes longer, the incident portion 53 cannot cover the light distribution angle θ, and many light fluxes are detached from the incident portion 53, the light distribution efficiency of the light guide 51 is lowered, and the removed light fluxes around the incident portion 53. There is a problem that the holder 54 emits light. Further, the gap (air layer) 58 between the incident portion 53 and the holder 54 may adversely affect the light distribution characteristics of the light guide 52.

Therefore, an object of the present invention is to provide a light guide that can protect the incident portion of the light guide from the heat generated by the semiconductor light source without reducing the light distribution efficiency.

In order to solve the above-mentioned problems, a light guide of the present invention includes an incident part that makes light emitted from a semiconductor light source incident on a light guide formed of a transparent material, and a protective part that protects the incident part from heat generated by the semiconductor light source. Is provided.

Here, the shape of the light guide is not particularly limited, and can be appropriately selected according to the application, such as a rod shape, a strip shape, or a plate shape. In the case of a rod-shaped or strip-shaped long light guide, one end surface in the longitudinal direction functions as an incident surface and faces the semiconductor light source. In practicing the present invention, the incident surface of the light guide can be the end surface of the incident portion or the end surface of the protective portion.

In some embodiments of the present invention, the end surface of the protection unit functions as an incident surface of the light guide, and light emitted from the semiconductor light source enters the incident unit through the protection unit. In this case, preferably, the incident portion can be formed of the first transparent material, and the protective portion can be formed of the second transparent material having a softening point higher than that of the first transparent material.

Specifically, the first transparent material of the incident part can be made of synthetic resin, and the second transparent material of the protective part can be made of glass. Alternatively, the first transparent material may be an acrylic resin (PMMA) having a relatively low softening point, and the second transparent material may be a polycarbonate resin (PC) having a relatively high softening point.

In addition, it is also possible to mold the incident part with a transparent thermoplastic resin and mold the protective part with a transparent thermosetting resin. As the transparent thermosetting resin, a resin material having no softening point such as silicone or epoxy can be used.

In another embodiment of the present invention, the end surface of the incident portion functions as the incident surface of the light guide, and light emitted from the semiconductor light source is directly incident on the incident portion. In this case, the peripheral surface of the incident part can be covered with a heat radiating cover, and this cover can be used as a protective part of the light guide. As the heat radiation cover, a material that can efficiently absorb the heat stored in the incident portion, for example, a material having high thermal conductivity such as aluminum or CNT (carbon nanotube) can be preferably used.

In yet another embodiment of the present invention, the incident part includes a hypertrophy part integrally formed at the base end of the light guide, and the protection part includes a curved surface recessed in the end face of the hypertrophy part. According to this configuration, the heat capacity of the incident portion can be increased, and the concave curved surface (incident surface of the light guide) of the protection portion can be separated from the semiconductor light source.

In addition, in order to separate the incident surface of the light guide from the semiconductor light source, in one embodiment of the present invention, the protective portion includes a cylindrical cap attached to the incident portion, and the inner periphery of the cap is separated from the semiconductor light source. A reflection surface that reflects the light toward the incident portion is formed.

According to the light guide of the present invention, since the light guide itself includes the protection part, it is not necessary to intervene another member between the light guide and the semiconductor light source. For this reason, the incident part of the light guide is brought close to the semiconductor light source, so that the light emitted from the semiconductor light source can be efficiently distributed and the incident part can be protected from the heat generated by the semiconductor light source.

It is a principal part perspective view of the light guide which shows Example 1 of this invention. It is sectional drawing which shows the incident part and protection part of a light guide. It is a perspective view which shows the connection structure of an incident part and a protection part. It is sectional drawing which shows another connection structure of an incident part and a protection part. It is a principal part perspective view of the light guide which shows Example 2 of this invention. It is the principal part perspective view and sectional drawing of the light guide which show Example 3 of this invention. It is principal part sectional drawing of the light guide which shows Example 4 of this invention. It is the schematic which shows the light guide of the lamp | ramp for vehicles. It is sectional drawing which shows the conventional light guide holder.

Hereinafter, an embodiment in which the present invention is embodied in a light guide for a vehicle lamp will be described with reference to the drawings. As shown in FIG. 8A, the light guide 11 includes a light guide body 12 formed of a transparent material into a rod shape. The light guide 12 includes an incident portion 13 that receives light emitted from the semiconductor light source 3, an emission portion 14 that emits incident light to the front of the vehicle lamp 1, and a protection portion that protects the incident portion 13 from heat generated by the semiconductor light source 3. (Not shown in FIG. 8).

Hereinafter, the configuration of the protection unit will be described in detail with some examples. 1 to 8, the same or similar components are denoted by the same reference numerals.

1 to 4 show Embodiment 1 of the present invention. As shown in FIG. 1, the light guide 11 of Example 1 includes an incident portion 13 and a protection portion 16 having the same diameter on the longitudinal axis or the optical axis A of the rod-shaped light guide 12. The protection unit 16 is located at the proximal end of the light guide 12, one end surface of the protection unit 16 (end surface 15 of the light guide 12) faces the semiconductor light source 3, and the other end surface 16 a of the protection unit 16 is the incident unit 13. It connects so that it may closely_contact | adhere to the one end surface 13a (refer FIG. 2).

As shown in FIGS. 2A and 2B, the incident portion 13 is formed of the same first transparent material as the emission portion 14 (see FIG. 8), and the protection portion 16 has a higher softening point than the first transparent material. Molded with a second transparent material. For example, as shown in FIG. 2A, PMMA (acrylic resin) or PC (polycarbonate resin) is used for the first transparent material of the incident portion 13, and glass is used for the second transparent material of the protective portion 16. Alternatively, as shown in FIG. 2B, PMMA can be used for the first transparent material, and PC can be used for the second transparent material. The incident part 13 shown in FIG. 2 (c) is molded from a transparent thermoplastic resin such as PMMA or PC, and the protective part 16 is molded from a transparent thermosetting resin such as silicone (SI) or epoxy (EP). Yes.

As shown in FIG. 3A, the incident portion 13 and the protection portion 16 are connected to the end faces 13a and 16a (see FIG. 1) with a transparent adhesive 17, or as shown in FIG. Each peripheral surface may be connected by a coupling 18. Alternatively, the incident portion 13 and the protection portion 16 can be simultaneously molded by a two-color molding method as shown in FIG. 4A, and are coupled using a screw member 19 as shown in FIG. 4B. You can also In either case, both the optical discs 13 and 16 are connected so that there is no optical axis deviation and no air layer is interposed between the end faces.

According to the light guide 11 of the first embodiment configured as described above, the protective portion 16 is disposed on the proximal end side with respect to the incident portion 13, and the protective portion 16 is a transparent material having a softening point higher than that of the incident portion 13. Therefore, it is not necessary to interpose a separate member for heat insulation between the light guide 12 and the semiconductor light source 3. For this reason, the end surface 15 of the light guide 12 can be directly opposed at a position close to the semiconductor light source 3, and the end surface 15 covers the light distribution angle θ (see FIG. 2) without excess or deficiency. Light emission can be efficiently distributed in front of the lamp. As shown in FIG. 4, the protection unit 16 can be made to face a plurality of semiconductor light sources 3.

FIG. 5 shows a second embodiment of the present invention. In the light guide 11, the end surface of the incident portion 13 is equal to the end surface 15 of the light guide 12, and the peripheral surface of the incident portion 13 is partially or entirely covered with the heat dissipation cover 21. The heat radiating cover 21 is a protective part of the incident part 13, and for example, as shown in FIG. 5A, a sheet-like or film-like member made of CNT is wound around the incident part 13, or FIG. As shown in FIG. 4, the incident portion 13 is made to be a semiconductor light source (not shown) by inserting an aluminum cylindrical member into the incident portion 13 or depositing a metal vapor deposition film on the peripheral surface of the incident portion 13. Protect from heat generation. Therefore, according to the light guide 11 of Example 2, there is an advantage that the light guide body 12 can be formed at low cost with one kind of transparent resin material over the entire length.

FIG. 6 shows a third embodiment of the present invention. In the light guide 11, an egg-shaped enlarged portion 23 is integrally formed at the base end of the light guide 12. The enlarged portion 23 is an incident portion that receives light from the semiconductor light source 3 and functions to increase the heat capacity of the incident portion. The end surface of the enlarged portion 23 (end surface 15 of the light guide 12) is provided with a curved surface 24 as a protective portion, and the transparent resin of the enlarged portion 23 is separated from the semiconductor light source 3. Is supposed to protect. Therefore, according to the light guide 11 of the third embodiment, there is an advantage that the heat loss of the incident portion can be easily suppressed, particularly by simply changing the shape of the base end portion of the light guide 12.

FIG. 7 shows a fourth embodiment of the present invention. The light guide 11 has caps 26 and 27 made of metal or heat-resistant resin as protective portions attached to the incident portion 13, and a reflection surface that reflects light emitted from the semiconductor light source 3 toward the incident portion 13 on each inner periphery. 26a and 27a are provided by aluminum vapor deposition. The cap 26 shown in FIG. 7A is formed in a cylindrical shape that spreads at the bottom, and a stepped reflection surface 26a is provided on the inner periphery. The cap 27 shown in FIG. 7B is formed in a cylindrical shape, and a flat reflecting surface 27a is provided on the inner periphery. Therefore, according to the light guide 11 of the fourth embodiment, in particular, the end face 15 of the light guide 12 is separated from the semiconductor light source 3 and the caps 26 and 27 function as a light collecting and heat radiating member. There is an advantage that heat loss can be effectively suppressed.

In addition, this invention is not limited to the said Example, For example, Example 2 shown in FIG. 5 is combined with Example 1 shown in FIG. 2, or the thermal radiation cover 21 of Example 2 is shown in FIG. Examples 1 to 4 can also be implemented in an appropriate combination, such as covering the enlarged portion 23 of Example 3, and the light guide of the present invention can also be applied to various optical devices other than vehicular lamps. The shape and configuration of each part can be changed as appropriate without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 1 Vehicle lamp 3 Semiconductor light source 11 Light guide 12 Light guide 13 Incident part 16 Protective part 21 Radiation cover 23 Enlarged part 24 Curved surface 26 Cap spread | extended from the skirt 26a Reflective surface 27 Step-shaped cap

Claims (8)

A light guide, wherein a light guide formed of a transparent material is provided with an incident portion that receives light emitted from a semiconductor light source and a protective portion that protects the incident portion from heat generated by the semiconductor light source. The light guide according to claim 1, wherein the incident portion is formed of a first transparent material, and the protection portion is formed of a second transparent material having a softening point higher than that of the first transparent material. The light guide according to claim 2, wherein the first transparent material includes a synthetic resin, and the second transparent material includes glass. The light guide according to claim 2, wherein the first transparent material includes an acrylic resin, and the second transparent material includes a polycarbonate resin. The light guide according to claim 1, wherein the incident portion is formed of a transparent thermoplastic resin, and the protection portion is formed of a transparent thermosetting resin. The light guide as described in any one of Claims 1-5 in which the said protection part contains the thermal radiation cover which coat | covers the surrounding surface of the said incident part. The light according to any one of claims 1 to 6, wherein the incident portion includes an enlarged portion integrally formed at a proximal end of the light guide, and the protective portion includes a curved surface recessed in an end surface of the enlarged portion. guide. The said protection part contains the cylindrical cap attached to the said incident part, The reflective surface which reflects the light from a semiconductor light source toward an incident part is formed in the inner periphery of a cap. The light guide as described in any one.

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