JPH07296605A - Headlamp for vehicle - Google Patents

Abstract

PURPOSE:To provide a headlamp for a vehicle capable of performing low/high beam switching even with a two-lamp type, in the vehicle use headlamp of projector system. CONSTITUTION:A device comprises a reflector 1 of almost elliptic shape, light source 2 arranging an emitting part so as to come to the first focal point of the reflector 1, projection lens arranged before the light source 2 to project light to the front and a liquid crystal device 4 arranged between the light source 2 and the projection lens 3. Light toward the projection lens 3 is distribution controlled by the liquid crystal device 4, and by changing its condition, a light distribution pattern is changed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projector type vehicle headlight.

[0002]

2. Description of the Related Art A conventional projector-type vehicle headlight has a structure shown in FIG. 4, in which 1 is a substantially ellipsoidal reflector, and 2 is a light-emitting portion which is the first focus of the reflector 1. The light sources 3 arranged are a projection lens for projecting light forward, and 5 is a light shielding plate arranged near the second focus of the reflector 1 for controlling light distribution.

In the conventional projector type vehicular headlamp having the above-described structure, the reflector 1 has two focal points because the reflector 1 has a substantially ellipsoidal shape, and the light emitting portion is the first focal point of the reflector 1. The light emitted from the light source 2 arranged so as to be curved is collected at the second focal point of the reflector 1, but a part of the light is partially absorbed because the light shielding plate 5 is disposed in the vicinity of the second focal point of the reflector 1. The light that has been cut and not cut by the light shielding plate 5 is projected forward by a projection lens having the second focus of the reflector 1 as a focal point to obtain a low-beam light distribution pattern shown in FIG. And get the irradiation area. That is, by disposing the light shielding plate 5 in the vicinity of the second focus of the reflector 1, light unnecessary for light distribution is cut and light distribution control is performed.

In this type of vehicle headlight, the light passes well and almost no light leaks to the surroundings, so the driver of the oncoming vehicle hardly feels glare. It is a light.

[0005]

However, in the conventional structure as described above, the light distribution control is performed by cutting the unnecessary light in the light distribution by the light shielding plate 5, so that the headlamp dedicated to the low beam or the high beam is provided. However, there is a problem that high beam / low beam cannot be switched unless it is a four-lamp type.

An object of the present invention is to solve the above-mentioned conventional problems, and an object of the present invention is to provide a projector-type vehicular headlamp which can switch between a low beam and a high beam by a two-lamp system.

[0007]

In order to achieve the above object, the present invention provides a reflector having a substantially ellipsoidal shape, a light source arranged such that a light emitting portion is located at a first focal point of the reflector, and the reflector. A projector-type vehicular headlamp having a projection lens for projecting light condensed at a second focal point forward, comprising a liquid crystal device for controlling light distribution between the light source and the projection lens. Be prepared.

[0008]

According to the present invention, the light distribution state of the liquid crystal device at the time of low beam and high beam is changed and the light distribution pattern is changed by controlling the light traveling from the reflector to the projection lens.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a vertical sectional view of a vehicle headlamp according to an embodiment of the present invention.

In FIG. 1, reference numeral 1 is a substantially ellipsoidal reflector, 2 is a halogen lamp serving as a light source arranged so that a light emitting portion is at the first focal point of the reflector 1, and 3 is arranged in front of the halogen lamp 2. The projection lens 4 that projects the emitted light forward and focuses the second focus of the reflector 1 is a liquid crystal device that performs light distribution control.

The operation of the vehicle headlamp of this embodiment constructed as described above will be described below. First, the light emitted from the halogen lamp 2 is reflected by the reflector 1 and focused on the second focal point of the reflector 1 and projected forward by the projection lens 3, but the liquid crystal device 4 changes the light transmittance. Since it has a controllable structure, by arranging the liquid crystal device 4 between the halogen lamp 2 and the projection lens 3, it is possible to control the light directed to the projection lens 3.
The light distribution pattern can be changed by changing the state of the liquid crystal device 4.

That is, the state of the liquid crystal device 4 is changed between the low beam and the high beam, and when the low beam is used, the state shown in FIG.
The state as shown in FIG. 2 is set so that the state becomes as shown in FIG. In the state shown in FIG. 2 (a) at the time of low beam, the light is cut in the substantially lower half, and the other portions are controlled so that the light is transmitted.
In the state shown in (b), the light is not cut and is controlled so that all the light is transmitted, so that the light distribution pattern shown in FIG. A light distribution pattern as shown in FIG. 3B can be obtained. The region for cutting the light at the time of low beam may be left-right symmetric or left-right asymmetric.

As described above, according to this embodiment, the light source 2
The liquid crystal device 4 is arranged between the projection lens 3 and the projection lens 3, and the light distribution pattern can be changed by changing the state of the liquid crystal device 4. In the projector type vehicle headlight, even a two-lamp type low beam type can be used. / High beam can be switched.

Although the light source 2 is a halogen lamp in this embodiment, it may be a discharge lamp such as a metal halide lamp. Further, although the liquid crystal device 4 is arranged between the first focus and the second focus of the reflector 1, the projection lens 3
May be disposed between the second focal point of the reflector 1 and the second focal point of the reflector 1, and the more the liquid crystal device 4 is disposed farther from the light source 2, the less likely it is to be affected by heat from the light source 2 and the reliability is improved.

Although the liquid crystal device 4 is arranged so as to cover the entire front surface of the reflector 1, it may be made small so as to cover a part thereof. In this case, the cost and power consumption of the liquid crystal device 4 can be reduced, and further the cost and power consumption of the entire headlamp can be reduced.

Furthermore, the transmittance of the liquid crystal device 4 is 0% or 100%.
The light distribution was controlled as%, but it is also possible to control the light distribution by using an intermediate value such as 50%, which makes it easier to find obstacles and pedestrians in the peripheral area during low beams, and to improve visibility. You can

[0017]

As described above, according to the present invention,
A liquid crystal device for controlling light distribution between the light source and the projection lens is provided, and the light distribution pattern can be changed, so that the light distribution pattern can be changed. Low beam / high beam can be switched even with the two-lamp system.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a vehicle headlamp according to an embodiment of the present invention.

FIG. 2A is a diagram showing a low beam state of the liquid crystal device of the same embodiment, and FIG. 2B is a diagram showing a high beam state of the liquid crystal device of the same embodiment.

FIG. 3A is a diagram showing an irradiation range of the vehicle headlamp of the same embodiment when a low beam is emitted; FIG. 3B is a diagram showing an illumination range of a vehicle headlight of the same example when a high beam is emitted;

FIG. 4 is a vertical sectional view of a conventional vehicle headlamp.

[Explanation of symbols]

 1 reflector 2 light source 3 projection lens 4 liquid crystal device

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masaaki Ochi 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (1)

[Claims] 1. A reflector having a substantially ellipsoidal shape, a light source arranged such that a light emitting portion is located at a first focal point of the reflector, and a projection lens arranged in front of the light source and projecting light to the front. A projector-type headlight equipped with,
A vehicle headlamp, comprising a liquid crystal device for controlling light distribution between the light source and a projection lens, and configured to switch a light distribution pattern.