JPH0434802A - Optical system of headlamp for vehicle - Google Patents

Abstract

PURPOSE:To obtain a desired light distribution pattern through the luminous flux of a reflector by using a certain structured surface as a reflector part. CONSTITUTION:The focal point F of radiation rays is defined as an origin of coordinates of a crossing axis 3. The reflecting surface of a reflector 11 is set in such a way that the angle theta of the light ray reflected at x/2 becomes zero. Outside a reference point x/2, thetan is reduced in proportion to {(x/2)-xn}<2>, and it becomes -theta deg. on the right end point, while, in the left direction from the reference point, thetan is increased in proportion to {(x/2)-xn}, and the shape of the reflector 11 is set in such a way that it will be theta deg. on the point (center) where an X coordinate is zero. Areas 14r, 14l are overlapped with each other on a screen at the time, and the light ray distribution pattern that is slightly extended in the upward direction at a diffusion angle theta deg. is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical system for a headlamp mounted on an automobile or the like, and particularly to an optical system characterized by the shape of a reflector.

[Conventional technology]

FIG. 4 shows a conventional headlamp that is widely used, and FIG. 4 (B) is a horizontal sectional view.

A light source bulb (not shown) is installed near the focal point F of the paraboloid of revolution fil.

The light emitted from the light source bulb is reflected by the parabolic mirror 1 of revolution and enters the prism lens 2 as a parallel beam of light in the direction of the optical axis Z.

The parallel light beam incident on the prism lens 2 is diffused by an angle θ1 to the left and right by the prism lens 2.

The light distribution pattern of a conventional headlight of this type is shown in Figure 4 (
As shown in A), the light distribution is relatively uniform over a range of angle θ from left to right.

However, it is hoped that an optical system will be developed in which a desired light distribution pattern can be obtained by using a transparent lens or a simple prism lens that is close to a transparent lens without using the prism lens 2.

FIG. 5 shows a known example different from the above.

As seen in FIG. 3B, the diffused reflector 3 of this known example receives light emitted from a point F, and reflects the light approximately parallel to the optical axis Z at the center of the reflector, while reflecting the light at the periphery. The light is reflected in a direction that opens with respect to the optical axis Z (expands in front) as it moves to the optical axis Z, and is reflected in a direction that opens at an angle θ at both left and right ends.

In the light distribution pattern of this type of headlamp, the amount of irradiation light is too small at both left and right ends, as shown in FIG.

Moreover, the auxiliary spherical mirror 4 cannot be provided at the position shown by the broken line.

The configuration shown in FIG. 6 is known as an improved example that eliminates the drawbacks of the known example shown in FIG. 5, allows the installation of the auxiliary spherical mirror, and increases the amount of light at both left and right ends.

The special reflector 5 of this known example reflects the light emitted from the point F in a direction that opens outward by an angle θ at the center, and reflects it at both left and right ends so as to form a light beam parallel to the optical axis.

However, in the headlight of this known example (FIG. 6), the amount of light near the center is insufficient, as shown in the light distribution pattern in FIG. 6(A).

In view of the above circumstances, we have developed an optical headlamp for a vehicle that can be illuminated uniformly within the range of angle θ in the left-right direction and that can also be used in conjunction with an auxiliary spherical mirror (for example, 4 shown in FIG. 5(B)). As a system, the shape of the reflecting surface and the position of the light source in a headlamp in which a light source is installed opposite to the reflecting surface of a concave mirror and a lens covering the front opening of the concave mirror is configured as follows. is possible.

(a) The reflective surface of the concave mirror has a shape formed by connecting a number of paraboloids of revolution that share a focal point, and (b) the central axis of each of the multiple paraboloids of revolution is relative to the optical axis of the lamp. , intersect in the horizontal plane, and (C) the angle of intersection between the optical axis and the central axis is
Near the center of the concave mirror, there is an angle θ to both the left and right sides.
The intersecting angle is inclined inward by an angle θ in the convergence direction at both left and right ends of the concave mirror, and gradually changes between these angles.

The above configuration is created by the present inventor and is currently being filed separately (Japanese Patent Application No. 63-300973) (hereinafter referred to as the prior application).

According to the configuration of the above-mentioned prior application, the left light that comes out from the focal point and is reflected by the paraboloid of rotation becomes parallel to the optical axis, so the direction of the reflected light is between angle θ and angle -θ in the horizontal plane. Almost uniformly distributed.

Furthermore, since the central portion of the reflecting surface reflects in the direction of diffusion at each angle θ y to the left and right, auxiliary spherical mirrors can be provided in the range of the left and right angles θ (range of the angle 2θ).

FIG. 7 shows the special reflector 6 in the optical system according to the invention of the prior application, FIG. 7(A) is a schematic horizontal sectional view, and FIG. 7(B) is an explanatory view thereof.

In FIG. 7(B), 2 is the optical axis of the lamp, and X is the horizontal axis perpendicular to the optical axis.

Assume a paraboloid of revolution Pb having a focal point at point F and a center axis Zb tilted clockwise with respect to the optical axis 2.

Furthermore, a paraboloid of revolution ph having a focal point at point F and a central axis Zh tilted counterclockwise with respect to the optical axis Z is assumed.

Then, a plurality of paraboloids of revolution are set by interconnecting these paraboloids of revolution Pb+Pds ph, and a reflecting surface is constructed along this composite paraboloid of revolution.

In the above-mentioned FIG. 7(B), for convenience of explanation, three paraboloids of revolution were set, but in FIG. 7, the left,
Eight paraboloids of revolution were set up and connected together.

In FIG. 7(A), Za-Zh are the central axes of eight paraboloids of revolution, respectively. A paraboloid of revolution (not shown) is assumed, with the intersection F of these eight central axes as the focal point.

In FIG. 1(A), Pa is a part of a paraboloid whose focal point is F and whose central axis is Za.

Pb is a part of a paraboloid with F as the focal point and Zb as the central axis.

Pc is a part of a paraboloid with F as the focal point and zo as the central axis.

Pd is a part of a paraboloid with F as a focal point and zd as a central axis.P is a part of a paraboloid with F as a focal point and ze as a central axis.

Pf is a part of a paraboloid with F as the focal point and Zf as the central axis.

P is a part of a paraboloid with F as the focal point and Zg as the central axis.

Ph is a part of a paraboloid with F as the focal point and Zh as the central axis.

Emitted from a light source (not shown) located at the focal point F,
The light reflected by the paraboloid of revolution Pa-ph is indicated by the arrow a
- It is reflected parallel to the central axis za-Zb as shown by the arrow.

In this way, the light emitted from the light source (not shown) located at the focal point F is emitted in each direction from arrow a to the left,
It is diffused to the right within the range of angle ±θn.

The light of the arrows a - h reflected by the paraboloid of revolution Pa-ph has a large luminous flux density when it is directed to the right as shown by the arrow a, and a small luminous flux density when it is directed to the left as shown by the arrow . A light distribution pattern as shown in Figure (A) is obtained.

In FIG. 7(A), although the optical path is omitted in the left half of the figure, a symmetrical optical path with respect to the optical axis Z is formed.

Therefore, the light distribution pattern caused by the left half is shown in Figure 8 (
As shown in B), the left and right hand is different from that shown in FIG.

Therefore, the light distribution pattern for the entire headlight of this example is shown in Figure 8 (C), which is a combination of Figure 8 (A) and Figure 8 (B).
), and suitable light distribution characteristics can be obtained.

That is, a uniform illuminance distribution can be obtained within the range of angle θ from left to right.

Furthermore, as can be easily understood from Fig. 7(A), the optical path of the reflected light (arrow a - = h) does not pass through the central front part of the special reflector of this example, so it is as shown in Fig. 9. This is suitable for installing the auxiliary spherical mirror 4.

When the auxiliary spherical mirror 4 is provided as in this example (FIG. 9), the light beam in the range of an angle 2θ forward from the light source (located at the focal point F) can also be effectively utilized. When the invention of this prior application is applied, the light distribution pattern explained with reference to FIG. 8 can be obtained, so that the clear lens 8 can be used as the front lens.

[Problem to be solved by the invention]

As explained above, according to the optical system according to the invention of the earlier application, by using mostly clear lenses, the range forming an angle θm with respect to the optical axis Z is centered on the front of the headlight. can be illuminated uniformly.

However, in the invention of the earlier application, the aim is to achieve uniformity of the left and right illuminance distribution in the light distribution pattern,
It is not possible to arbitrarily set the luminous flux density at the center.

The present invention has been made in view of the above-mentioned circumstances, and it is possible to obtain a desired light distribution pattern using a reflector without relying on light control by a front lens, and to set the luminous flux density at the center arbitrarily. The purpose of the present invention is to provide an optical system for a vehicle lamp.

[Means to solve the problem]

In order to achieve the above object, the optical system of the present invention, when mounted on a vehicle, has a horizontal line in the traveling direction of the vehicle as the Y axis, a horizontal line orthogonal to the Y axis as the X axis, and a vertical line as the Y axis, The present invention is characterized in that a large number of planes N including the Y axis and forming an angle n with the X axis are assumed, and a plane configured as described below is used for at least a portion of the reflector.

A, a cross section taken by a plane parallel to the Z-Y plane forms a parabola whose axis of symmetry is a line parallel to the Y axis, or a curved line approximating the parabola.

b, a cross section taken by a plane parallel to the z-x plane has a shape that reflects the light emitted from the focal point of the parabola in a direction that is not parallel to the Z axis.

The reflection point whose distance from the reflector reference point is n is Xn
The angle that the reflected light at the reflection point Xn makes with the Z-Y plane is θ
The angle θn is proportional to or inversely proportional to n to the 7th power.

However, the distance n is a variable.

[Effect]

According to the above configuration, the luminous flux reflected by the reflector is
They are approximately parallel in the vertical direction. This is because the vertical cross section of the reflector has a parabolic shape. However, as a practical matter, the light source has a certain size, so the light is not completely parallel but shows some diffusion. This slight diffusion in the vertical direction is not only practically harmless, but is also suitable for the light distribution performance of vehicle headlamps.

Further, according to the above configuration, by changing the value of (■), the luminous flux density at the center changes. Thereby, a desired light convergence degree can be obtained by appropriately selecting the value of V.

〔Example〕

FIGS. 1 and 2 show an embodiment of an optical system according to the present invention. FIG. 1 is an optical path diagram in which an optical path is drawn in a horizontal section of the beam reflector 11, and FIG. 2 is an optical path diagram in which an optical path is drawn in a vertical section of the reflector 11.

The reference numeral 12 shown in FIG. 2 is a light source bulb, and the reference numeral 13 is a transparent front lens.

The vertical cross section of the glue deflector 11 of this example has a parabolic shape with the Z axis as the axis of symmetry, and F is its focal point.

Z is a horizontal axis, Y is a vertical axis, or a horizontal axis perpendicular to these.

The light emitted from the filament of the light source bulb positioned at the focal point F and reflected by the reflector 11 becomes a parallel light beam in the optical axis Z direction.

However, since the filament of the light source bulb 12 actually has a certain size, the reflected light is slightly diffused in the vertical direction.

12a shown in FIG. 1 is the filament of the light source bulb 12, point F is the focus of the parabola, and x
, y, z are the coordinate origins of three orthogonal axes.

The glue flaper 11 of this example has a left-right symmetrical shape with respect to the Z-axis.

χ is the X coordinate of the rightmost point of the reflector 11.

Therefore, the X coordinate of the leftmost point of the reflector 11 is 1χ.

Since the reflector 11 is bilaterally symmetrical, the optical path is also bilaterally symmetrical. Therefore, next, the optical path in the right half will be mainly explained.

The angle at which the light reflected by the reflector 11 swings to the right with respect to the two axes is expressed as 00, and the angle at which the light deflects to the left is expressed as 100.6 The angle θ of the reflected light at the point where the X coordinate is x/2 is 0 ( Z
The reflective surface of the reflector 11 is set so as to be parallel to the axis.

The X coordinate is χ. Let θn be the angle that the reflected light that is reflected at a certain reflection point makes with the Z axis.

In this embodiment, the point whose X coordinate is χ/2 is used as the reference point, and v=2.

Then, the distance in the X-axis direction between the reflection point and the reference point is (χ
/2)-χ. bawl.

Then, outside the reference point χ/2 above (to the right in the figure)
Then, as θn decreases in proportion to ((χ/2)-χ□)2 and reaches 100 at the rightmost point, and as it moves to the left from the reference point χ/2, °C1θn is (
(χ/2)−χ. ), and the shape of the reflector 11 is set so that the X coordinate increases in proportion to 0 and reaches 00 at the point (center) of the X coordinate O.

As described above, it is easily possible to design the shape of the reflector 11 by taking a large number of points χn (n is a variable) by using an electronic computer.

FIG. 3 is an explanatory diagram of the light distribution pattern in this embodiment. With the optical system of this example (Fig. 1), when the screen installed in front of the headlight is illuminated without a front lens attached,
The area shown is as shown in Figure 3 CB). 13r indicated by a solid line in the same figure is an area where the light reflected by the right half of the flapper 11 reaches, as will be explained with reference to FIG.

The luminous flux reflected by the left half of the glue flaper 11 in Fig. 1 is
As shown in the area 141 indicated by the broken line in FIG. 3(B), it forms a left-right symmetrical shape.

The reason why the area 14r forms an elongated isosceles triangle with the apex facing left is as follows.

Now, if a point light source is placed at the focal point F, the light distribution pattern should form a thin horizontal line, but since the filament 12a having a certain size is used as the light source, the filament 12a will appear on the screen. A statue of is tied.

Although the area of the reflecting surface of the reflector 11 is finite, there are countless reflection points within this area. Therefore,
The light distribution pattern on the screen is formed by overlapping countless filament images.

Then, as shown by arrow j in FIG. 1, the reflector 11
The light incident on the right end of the screen and reflected in the -θ0 direction as indicated by the arrow forms a small filament image on the screen because its reflection point is far from the light source.

In contrast, the light reflected at the center of the reflector 11 in the 00 direction as indicated by arrow q forms a large filament image on the screen because its reflection point is closer to the light source.

For these reasons, area 14 shown in Figure 3(B)
r, 14Ω overlap on the screen, and as a result,
With the left and right diffusion angle θ0, a light distribution pattern with a slight spread in the upward direction can be obtained.

In FIG. 3(B), HH is a horizontal line on the screen, and v-■ is also a vertical line.

The illuminance distribution on the line H-H is shown in FIG. 3(A).

Since the reflected light from the reference point (the point whose X coordinate is χ/2) shown in FIG. 1 is directed in the Z-axis direction, it forms the center of the light distribution pattern.

Since the reflection angle θn increases in proportion to the square of the distance from the reference point as the distance from the reference point increases, the illuminance curve (FIG. 3(A)) decreases as the distance from the center increases.

In this embodiment, v = 2, but if this value is appropriately selected, the light convergence at the center of the illuminance curve shown in FIG. 3(A) can be changed arbitrarily.

〔Effect of the invention〕

As explained above, according to the optical system of the vehicle headlamp according to the present invention, a desired light distribution pattern can be obtained by the luminous flux reflected by the reflector without relying on light control by the front lens, and moreover, The luminous flux density can be set arbitrarily.

[Brief explanation of drawings]

1 to 3 show an embodiment of the optical system of a vehicle headlamp according to the present invention. An optical path diagram in which the optical path is drawn in a cross-sectional view, Figure 3 (A) is a diagram showing the illuminance distribution on the H-H line, Figure 3
Figure (B) is a chart showing a light distribution pattern. 4(A), (B) to FIG. 6(A), (B) are explanatory diagrams of the conventional technology. 7(A), (B) to FIG. 9 are explanatory diagrams of the invention related to the preceding order. 1... Parabolic mirror of revolution, 2... Prism lens, 3...
... Diffuse reflector, 5, 6... Special reflector,
8... Clear lens, 11... Reflector according to the present invention, 12... Light source bulb, 12a... Filament, 13... Clear front lens.

Claims (1)

[Claims] 1. A horizontal line in the traveling direction of the vehicle when mounted on a vehicle is the Z axis, a horizontal line orthogonal to the Z axis is the X axis, a vertical line is the Y axis, including the Z axis, An optical system for a vehicle headlamp, characterized in that a number of surfaces N forming an angle n with respect to an axis are assumed, and a surface configured as described below is used for at least a portion of a reflector. A, a cross section taken by a plane parallel to the Z-Y plane forms a parabola whose axis of symmetry is a line parallel to the Z axis, or a curved line approximating the parabola. b. A cross section taken by a plane parallel to the Z-X plane has a shape that reflects the light emitted from the focal point of the parabola in a direction that is not parallel to the Z axis, and the distance from the reference point of the reflector is n. Reflection point
Let n be the angle that the reflected light at the reflection point X_n makes with the Z-Y plane as θn, and the angle θn is proportional to or inversely proportional to the vth power of n. However, the distance n is a variable.