1. Field of the Invention
The invention relates to a vehicular lamp and, more particularly, to a technique for forming an infrared ray reflective film on a light transmitting member or having a light transmitting member contain an infrared ray absorbent to prevent the incidence of infrared rays in sunlight.
2. Description of the Related Art
Japanese Patent Application Publication No. 2007-207527 (JP-A-2007-207527) describes a vehicular lamp in which a lamp unit is arranged inside a lamp casing. The lamp casing is formed of a lamp body and an outer cover that closes an opening of the lamp body. The lamp unit uses a light-emitting diode (LED) as a light source.
Such a lamp unit is formed of various components, such as a light source (light-emitting diode), a reflector, a shade and a projection lens, or a portion of the components.
In the above vehicular lamp, for example, light emitted from the light-emitting diode is reflected by the reflector toward the projection lens and is irradiated outward through the projection lens and the outer cover in a state where part of the light is blocked by the shade.
Incidentally, during running or stop of a vehicle outdoors, sunlight may enter the vehicular lamp. For example, when the optical axis of the vehicular lamp accidentally coincides with the traveling direction of sunlight during running or stop of the vehicle, sunlight passes along a path in the opposite direction to the path of light emitted from the light-emitting diode and enters the vehicular lamp. Then, the sunlight may possibly be collected at a focal point of the reflector or projection lens, a light-emitting point of the light-emitting diode, or the like.
If sunlight is collected in this way, for example, there is a possibility that inconvenience, such as melting or paint peeling of the shade located at the focal point of the reflector or projection lens and damage or breakage of the light-emitting diode, occurs.
Particularly, light emitted from the light-emitting diode does not include any heat, so the shade, or the like, located at the focal point at which light is collected is mostly formed of a resin material that requires less consideration of the influence of heat. Therefore, when sunlight is collected, melting, or the like, easily occurs.
In addition, infrared rays included in sunlight have a property as heat rays and have high heating performance. Particularly, it is necessary to suppress the incidence of infrared rays to the vehicular lamp.