JPH01302602A - Projector type headlight - Google Patents

Abstract

PURPOSE:To prevent the light distribution nonuniformity in a hot zone by providing fine irregularities on the reflecting surface of a reflecting mirror so as to generate the reflection deflection angle of 1 deg. or below with the irregularities. CONSTITUTION:Many fine recesses (a)-(i) with the reflection deflection angle of 1 deg. or below are arranged on the reflecting surface of a concave mirror so as to form an enveloping surface on the reference face of a rotary elliptic concave surface. The reflected light by a reflector 11 is applied with diffusion of 1 deg. or below at each reflection point on fine irregular surfaces. The focal point of the reflector 11 becomes a range having fine space expansion, not a point. As a result, if acts to gradate the real image of a filament and eliminates the irregularities of its contour. The light distribution nonuniformity in a hot zone can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a projector type vehicle headlamp, and particularly to a projector type headlamp with improved light distribution characteristics.

[Conventional technology]

Automobile headlights must have a light distribution pattern that brightly illuminates the area in front of the vehicle's own lane and does not dazzle oncoming vehicles.

A projector-type automobile headlamp has been proposed as a headlamp that has light distribution characteristics that meet the above requirements, has a simple lens configuration, and can be made compact in overall size. The latest technology regarding this projector type headlight is known, for example, in Japanese Patent Application Laid-Open No. 58-209801.

FIG. 3 shows the above-mentioned known projector type headlamp. This known example headlamp is provided with a shell-shaped reflector, and the axial cross section of the inner reflective surface of this reflector is a part of an ellipse. In a vehicle headlamp in which the eccentricity of the ellipse increases from the axial vertical longitudinal section to the axial horizontal longitudinal section, the inner tank portion of 101°lO2 of all axial sections is The focal point 105 is arranged such that the corresponding vertices 104 of the intra-vessel portions 101, 102 of all axial sections coincide.

101 is an outer focus of the ellipse 102, 110 is a light shielding plate-like dimmer, 112 is an outer focus of the ellipse 101, and 113 is a lens.

Figure 4 is a schematic representation of an example of this type of projector type headlamp. 5 is a side view, and FIG. 6 is a front view.

1 is a concave mirror, and F is its focal point. The light source bulb 2 is provided so that the filament is located near the focal point F mentioned above.

A convex lens that shares the light @Z with the concave mirror 1: 3
is provided.

4 indicates the meridional image plane of the convex lens 3, and the light (J) emitted from the light source and reflected by the concave mirror 1 enters this meridional image plane.

The incident light shown in "U" is modulated by the convex lens 3 and projected forward (to the right in FIGS. 4 and 5).

If a screen is provided near the meridional image plane and the light distribution pattern is shown as an isoluminous curve, the result will be as shown in FIG.

H-H is the horizontal line on the screen.

V-V is also a vertical line.

As shown in FIG. 4 and FIG. 6, a shade 4 having an edge along the meridional image plane is provided. For more information, see Part 6.
As shown in the figure, a cut line 4a is formed so as to recede from the meridional image plane ij. Figure 8 shows
The degree of overlap between the above-mentioned light distribution pattern (FIG. 7) and the shade 4 is shown. As shown in FIG. 8, the -L half of the luminous flux passes through. Although most of the lower half is blocked, light is allowed to pass through the portion corresponding to the cut line 4a.

As shown in Figure 2, the partially covered light beams are focused on the meridional image planes ij and intersect with each other, so the light beam projected in front of the headlight has a shape that is an inversion of Figure 8. form a pattern. FIG. 9 is an explanatory diagram showing the general shape of a light projection pattern using isoluminance curves on a screen provided in front of the headlight.

In FIG. 9, the area above the diagonal cut line Cj and the L side of the horizontal cut line ch is missing because the shadow of the shade 4 stands on end.

In addition, in a projector type headlamp in which the shade 4 is omitted, cut lines Ci and C are shown as imaginary lines.
Light is also distributed to one side of -I of h. Such a light distribution pattern is suitable when there are no oncoming vehicles.

[aI problem that the invention seeks to solve]

FIG. 10 is an explanatory diagram of the light distribution characteristics of a projector type headlamp without the shade 4. In FIG.

FIG. 10(A) is an isoluminance curve when a screen is irradiated, and the areas shown with spots are hot zones with an illuminance of 100 lux or more.

Since the filament 1- of the light source bulb 2 shown in FIG. 4 is not a pure point light source but has a coil shape, a real image of this filament is formed by a reflecting mirror (concave mirror).

The image of the filament produced on the concave mirror is shown in Fig. 2 (A).

As a result of such a real image onto the filament 1 being projected forward by the convex lens 3, the illuminance distribution in the hot zone (spotted area in FIG. 1O (A)) becomes non-uniform.

If the illuminance distribution on the H-11 line in Figure 10 (A) is graphed in correspondence with the figure, it will look like Figure 10 (B). If there is uneven illuminance, it becomes difficult for the driver to drive, and the accuracy of illuminance measurement deteriorates (measured values that do not represent the actual situation are obtained).7 The present invention was made in view of the above-mentioned circumstances. It is an object of the present invention to provide a projector type headlamp with no uneven light distribution (monotonous illuminance distribution) within a hot zone.

[Means to solve the problem]

The basic principle of the present invention, which was created to achieve the above object, is as follows.

That is, the optical path of the light reflected by the concave mirror is slightly diffused without affecting the overall function.

As a specific configuration for applying the above principle to practical use, the projector type headlamp of the present invention has the above-mentioned concave mirror configured as follows.

(a) The reflective surface uses a spheroidal concave surface as a reference surface.

(b) A large number of minute concave surfaces (or convex surfaces) are arranged in a row so that the reference surface is an envelope surface.

With the above configuration, it is easy to think that the reflected light beam has a diffusive quality, but one problem is the degree of the diffusiveness.

In other words, if the diffusivity is low, prevention of uneven light distribution will be incomplete.
If the diffusivity is excessive, the function as a projector type headlamp will be impaired.

Therefore, in the present invention, the reflection polarization angle of the minute concave surface (or convex surface) is limited to 1 degree or less.

In the present invention, the reflection deflection angle refers to the difference between the reflection angle due to minute concave or convex surfaces and the reflection angle of the reference surface, and this reflection deflection angle has a value that differs depending on the reflection point on the minute concavo-convex surface.

[Effect]

By taking the above measures, the light reflected by the reflector is given a diffusivity of 1 degree or less for each reflection point on the minute concave or convex surface.

In other words, the focal point of the reflector is not a point but a range having a minute internal curvature. As a result, the real image of the filament (conventional example) shown in FIG. 2(A) is blurred, and the unevenness of its outline is eliminated as shown in FIG. 2(B).

As a result, the unevenness (light distribution unevenness) at the peak portion of the illuminance curve (conventional example) shown in FIG. 10(B) is eliminated. As can be easily understood from the above-mentioned functions and effects, when carrying out the present invention, the above-mentioned minute concave and convex surfaces are

Even if it is not necessarily provided on the entire surface of the reflector, the unevenness (light distribution unevenness) in the peak portion can be reduced to a practically acceptable level.

〔Example〕

FIG. 1 is a schematic diagram showing an embodiment of a projector type headlamp according to the present invention, in which (A) is a front view of a concave mirror 11, and (B) is a front view of a concave mirror 11 and a convex lens 3. , a cross-sectional view taken along a horizontal plane including the optical axis, and FIG. 2C is a cross-sectional view taken along a vertical plane.

As shown in FIG. 1(A), a large number of minute concave spherical surfaces a, b=i are arranged on the reflecting surface of the concave mirror 11.

As shown in Figure 1 (B), concave spherical surfaces a and b are present in the horizontal section.
, c''i are arranged in a concave arc shape.

This concave mirror 11 is bilaterally symmetrical, and FIG. 1(A) shows a concave spherical surface only in the first quadrant, and the rest are omitted.

The actual dimensions of these concave spherical surfaces are about 1 m in diameter and about 1 μm in depth, but they are shown enlarged in FIG. 1.

When implementing the present invention, convex arcs may be arranged in place of the concave arcs.

(See FIG. 1(B)) In the conventional example, the light emitted from the first focal point F1 of the concave mirror 11 was focused on the second focal point F2, but due to the structure in which the concave spherical surfaces are arranged, the luminous flux is The light is slightly diffused and concentrated between points f and fz. In other words, point f
ly f2. As a result, this second falcon point F
The filament image formed on 2 is blurred in the horizontal direction as shown in FIG. 2(B).

When this blurred image is projected forward by the convex lens 3 shown in FIG. 1(B), it spreads by a small angle Δθ (within 1° in this example) as shown. As a result, Figure 10 (B
) (Conventional example) The unevenness at the peak portion of the illuminance curve disappears.

As shown in Figure 1 (C), light is diffused even in the vertical section, but since the maximum value of the reflection angle is 1 degree, it does not impair the overall function of the projector type headlamp. do not have.

〔Effect of the invention〕

As explained above, according to the projector type headlamp of the present invention, uneven light distribution within the hot zone can be eliminated.

[Brief explanation of the drawing]

FIG. 1 shows an embodiment of a projector type headlamp according to the present invention, in which (A) is a front view of a concave mirror, (B) is a horizontal sectional view of the concave mirror and a convex lens, and CC) is a vertical sectional view. . FIG. 2 is an explanatory diagram of a filament image. 3 to 9 are diagrams explaining the principle of a projector type headlamp. FIG. 10 is a light distribution characteristic chart. DESCRIPTION OF SYMBOLS 1... Concave mirror (reflecting mirror) of the conventional example, 2... Light source bulb, 3... Convex lens, 4... Shade, Lt... Concave mirror in the embodiment of the present invention.

Claims (1)

[Claims] 1. A light source bulb is installed near the focal point of the spheroidal reflector, and the light emitted from the light source bulb is reflected by the reflector and focused, and the reflected light is directed forward by a convex lens. In a projector-type headlamp for projecting images onto A projector-type headlamp characterized by the following configuration.