JPH0428101A - Optical system for vehicle head lamp - Google Patents

Abstract

PURPOSE:To simplify a constitution by getting rid of a front surface lens, by controlling the arrangement of light at surface shapes rotating at a plurality of rotary angle positions as the horizontal surface is being rotated around a light axis. CONSTITUTION:At a condition in which attachment is made to a vehicle, a horizontal axis in a vehicle advance direction is made to be a Z axis, and a horizontal axis and a vertical axis which meet at right angles with this Z axis, are made to be an X axis and a Y axis. A number of surfaces N which contain the Z axis and make an angle (n), are given, and the reflection light of light which is emitted from a point F on the Z axis and is incident on a point L on a reflector 11, is on a surface N containing the point L. Also, an angle thetamade by the reflection light and the Z axis is the larger, the nearer it is at a crossing point of the reflector 11 and the Z axis, and the smaller it is, the more distant from the crossing point, and the reflection light at the perimeter portion of the reflector 11 becomes almost parallel with the Z axis. Also, given that the maximum value of an angle made by the reflection light and the Z axis at every numbers of surfaces N whose angle made by vertical surfaces is (n), is thetamaxn, the larger thetamaxn is, as a surface N has the larger (n), and the smaller thetamaxn is, as a surface N has the smaller (n). Moreover, the angle (n) is a variable, and so a surface N varies in a rotary direction with the Z axis as a center, as the angle (n) varies.

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. 9 shows a conventional headlamp that is widely used, and FIG. 9 (B) is a horizontal sectional view.

A light source bulb (not shown) is installed near the focal point F of the rotating parabolic mirror 1.
is installed.

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 makes an angle θ to the left and right due to the prism lens 2. It is spread gradually.

The light distribution pattern of a conventional headlight of this type is shown in Figure 9 (
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. 10 shows a known example different from the above.

As seen in Figure (B), the diffuse reflector 3 of this known example receives the light emitted from the point F, and reflects the light approximately parallel to the optical axis 2 at the center of the reflector, and at the periphery. The light is reflected in a direction that opens (expands in front) with respect to the optical axis Z as it moves to the optical axis Z, and is reflected in a direction that opens at an angle θ1 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. 11 is known as an improved example that eliminates the drawbacks of the known example shown in FIG. 10, allows the installation of the auxiliary spherical mirror, and increases the amount of light at both left and right ends.

This known special reflector 5 reflects the light emitted from point F in a direction that opens outward by an angle θ1 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. 11),
As shown in the light distribution pattern in FIG. 2A, the amount of light near the center is insufficient.

Japanese Patent Application Laid-Open No. 6-1999 discloses an improved reflector for lamps that eliminates the drawbacks of the above-mentioned known examples and allows arbitrary light distribution characteristics to be obtained.
No. 0-86502, a reflector for lamps, is known.

The reflector for a lamp disclosed in the above publication has a shape as shown in Figures 6 and 7 of the publication, and has an angle with respect to the optical axis of the light incident from the light source toward the reflecting surface. θ, the light intensity of the light source 0, and the angle α of the reflected light with respect to the optical axis, −Igcosθ=Asina−CB+Aa)cosα+
While maintaining the relationship c, the coordinates of the point where the light emitted from the light source is incident at an angle θ with respect to the optical axis (If
) has a curved surface formed by rotating a continuous curve represented by The angle α is set to decrease as the angle α increases.

According to this known technique, as shown in FIG. 8 of the same publication, the degree of freedom in designing the light distribution in the left and right direction is increased; however,
As shown in FIG. 9 of the publication, the light distribution pattern is symmetrical both vertically and horizontally.

Such a phenomenon is difficult to avoid since the lamp reflector disclosed in the above-mentioned publication is a rotating surface about the optical axis 2.

Such a circular light distribution pattern (FIG. 9 of the same publication) can be used as an auxiliary headlamp, but is not suitable as a main headlamp.

In view of the above circumstances, uniform illumination can be achieved within the range of angle θ1 in the left-right direction, and an auxiliary spherical mirror (for example, 4 shown in FIG. 10(B)) can be used in combination. As an optical system for an automobile headlamp, a light source is installed opposite to the reflecting surface of a concave mirror, and a lens is provided to cover the front opening of the concave mirror. The following configuration may be considered.

(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.

(C) The intersecting angle between the optical axis and the central axis is inclined to the left and right by an angle θ near the center of the concave mirror, and the intersecting angle is inward at an angle θ at both the left and right ends of the concave mirror. , and gradually changes in between.

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 from angle θ to angle -θ in the horizontal plane. It is distributed almost uniformly between the two.

Moreover, since the central part of one reflecting surface reflects in the direction of diffusion of each angle θ to the left and right, an auxiliary spherical mirror can be provided in the range of the left and right angles θ (range of the angle 2θ).

FIG. 12 shows the special reflector 6 in the optical system according to the invention of the prior application, FIG. 12(A) is a schematic horizontal sectional view, and FIG. 12(B) is an explanatory diagram thereof.

In FIG. 12(B), Z is the optical axis of the lamp, and X is a 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*Pd*Ph, and a reflecting surface is constructed along this composite paraboloid of revolution.

In the above-mentioned Figure 12 CB), three paraboloids of revolution were set for convenience of explanation, but in Figure 12, eight paraboloids of revolution were set each on the left and right. were connected.

In FIG. 12(A), Z and -Zh are the central axes of eight paraboloids of revolution, respectively. Intersection point F of these eight central axes
A paraboloid of rotation (not shown) is assumed, with the focal point being the focal point.

In FIG. 1(A), Pa is a part of a paraboloid with F as the focal point and Z as the central axis.

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

Po is a part of a paraboloid with F as the focal point and zc as the central axis.

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

Pe is a part of a paraboloid with F as the focal point and Ze as the central axis.

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

Pg is a part of a paraboloid with F as the focal point and zg as the central axis.

ph is a portion 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 paraboloids of revolution Pa-Ph is indicated by the arrow a
~As shown by the arrow, it is reflected parallel to the central axis Z, -Zh.

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 spread to the right within an angle of ±θ.

The light of arrows a - h reflected by the paraboloids of revolution p and -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 . 13
A light distribution pattern as shown in Figure (A) is obtained.

In FIG. 12(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 generated by the left half is different in left and right directions from that shown in FIG. 13(A), as shown in FIG. 13(B).

Therefore, the overall light distribution pattern of the headlight in this example is the 13th light distribution pattern that is the sum of FIG. 13(A) and FIG. 13(B).
As shown in Figure (C), 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. 12(A),
Since 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, it is suitable for installing the auxiliary spherical mirror 4 as shown in FIG.

If an auxiliary spherical mirror 4 is installed as in this example (Fig. 14),
The light flux 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. 13 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, an angle θ is formed with the optical axis 2 with the front of the headlight as the center, using a mostly transparent lens. A range can be uniformly illuminated.

However, in the invention of the prior application, only the left and right illuminance distributions in the light distribution pattern were considered, and no consideration was given to the upper and lower illuminance distributions.

Therefore, in practical terms, the optical system according to the invention of the earlier application is extremely effective and valuable for headlights where vertical illuminance distribution is not a problem, such as auxiliary headlights such as fog lamps. However, this is not necessarily sufficient when the problem is horizontal and vertical light distribution.

That is, for example, as shown in FIG. 15, the angle θ is
The range of H2θH' and the angles θV and θV' in the upper and lower directions
Given a target light distribution pattern such as the range of , it is difficult to obtain the light distribution pattern shown in FIG. 15 by applying the invention of the prior application.

Furthermore, the horizontal cross section of the reflector is set by applying the optical system according to the prior application, and the cross section of the reflector along the vertical plane parallel to the optical axis Z is formed into a parabolic shape.

In the horizontal direction, the desired light distribution can be obtained within the range of angle θ1, while in the vertical direction, a slight light distribution can be obtained due to the diffusion caused by the size of the filament, but it is designed to achieve the desired light distribution. It is difficult to intend.

The present invention has been made in view of the above-mentioned circumstances, and is an improvement on the fact that the invention of the prior application was planar (that is, only the light distribution in the left and right directions was considered).

The objective is to provide an optical system for vehicles that is suitable for three-dimensional light distribution design (that is, considering vertical light distribution). The desired light distribution characteristics can be obtained in each direction (left and right, up and down), and the concentration and luminous intensity at the mouth and center can be set arbitrarily.

C. It is an object of the present invention to provide an optical system for a vehicle headlamp that can obtain a desired light distribution without being restricted by the external shape of a reflector.

[Means to solve the problem]

In the invention of the prior application, the light distribution in the horizontal plane including the optical axis Z was devised.

To put the basic principle of the present invention in a comparative manner, while rotating the above-mentioned horizontal plane around the optical axis Z, the light distribution on the rotating plane is controlled in a design manner at a plurality of rotation angle positions.

As a specific configuration based on the above-mentioned principle, the optical system of the vehicle headlamp according to the present invention has two axes that are horizontal lines in the traveling direction of the vehicle when it is attached to the vehicle, and are perpendicular to the Z-axis. The horizontal line is the X-axis, the vertical line is the Y-axis, and a number of planes N including the Z-axis forming an angle n with the X-axis are assumed, and a plane configured as shown below is used for at least a part of the reflector. It is characterized by

a, the reflected light of the light emitted from one point F on the Z axis and incident on the dot on the reflector is on the plane N including the dot.

b. The angle θ that the reflected light makes with the two axes is larger as it is closer to the intersection of the reflector and the two axes, and smaller as it is farther from the intersection, and the reflected light in the periphery of the reflector is approximately parallel to the Z-axis.

C6 For each of the many surfaces N whose angles with the vertical plane are n, the maximum values of the angles that the reflected light makes with the two axes are θ and aχ. When closed, the surface N with the larger angle n is θ, aχ. The surface N with large angle n and small angle n is θ, aχ. is small.

However, the angle n is a variable.

Therefore, as the angle n changes, the surface N is displaced in the rotational direction about the Z axis.

[Effect]

According to the above configuration, while rotating the plane including the optical axis 2, the light reflected by the reflector forms a desired illuminance distribution without the aid of a lens, no matter what rotation angle position is viewed.

In particular, the reflected light at the periphery of the reflector is reflected approximately parallel to the optical axis Z, resulting in a high illumination area (hot zone) at the center.
form.

Since the configuration is such that the reflected light around the reflector forms a hot zone, a desired light distribution pattern can be formed without being restricted by the contour shape of the reflector.

〔Example〕

FIG. 1 is a perspective view schematically depicting an embodiment of the optical system of a vehicle headlamp according to the present invention, and numeral 11 indicates a flapper constructed to apply the present invention.

Z is the optical axis of the reflector 11, which is used horizontally.

The point F on the optical axis Z is a theoretical focal point, and the following description will be made based on the case where a point light source is placed here.

Let us consider the case where a vertical screen 12 is placed in front of the headlight (in the direction of arrow Z), which is composed of the reflector 11 and a point light source. is the vertical axis of

A plane Nn that includes the optical axis Z and makes an angle n0 with respect to the vertical axis Y.

think of. The above n is a variable, and as the angle n changes, the surface Nn changes. rotates around the optical axis Z.

FIG. 11 depicts a state in which this angle n0 takes one value.

The illustrated lla is a light source bulb mounting hole.

In the illustrated arcuate curve, -LS is the plane Nn. This is a cut of Nyorori Frefta 11.

On the above cut curve, the point closest to the optical axis Z is Ls, and the farthest point is Le.

The light (arrow i) that is incident on a point Le corresponding to the peripheral part of the reflector 11 and reflected is parallel to the optical axis Z (i.e.
(at an intersection angle of 0° with optical axis 2).

Therefore, there should be a sufficient distance in front of the light (e.g. 10 meters).
On the screen 12 installed with .

The reason for this is that even if the surface N0' is rotated to assume various angular positions, all of the reflected light at the periphery becomes parallel to the optical axis Z and concentrates at the center.

Next, the reflected light at the point Ls closest to the optical axis Z (arrow j
) are the maximum angles θ and aχ with the optical axis 2.

bawl.

The light reflected at each point on the cut curve on the arc is one point L
The closer the point is to e, the smaller the angle of intersection with the optical axis Z becomes, and the closer it is to the point LS, the larger the angle of intersection with the optical axis Z becomes, approaching the angles θ and aχn'.

The shape of the reflector 11 to provide the above performance will be described later with reference to FIG. 5 and other figures.

The reflected light of the arrow j is reflected from the surface N. . It advances along the screen 12 and irradiates a point L6' corresponding to the angle θ+saχn'.

The illuminance distribution on the screen 12 shown in FIG.
A plan view of the light distribution pattern viewed in the direction is shown in FIG.

When the above angle is no, the reflected light is on the plane Nn. and the screen 12, and the spread of the light is θ, aχ
It becomes n'.

If the angle n0 becomes smaller, the spread angle θ of light increases.

aχn. becomes smaller, If the angle n0 above increases, the spread angle θ of light increases.

aχn. The shape of the reflecting surface of the reflector 11 is set so that the angle becomes large (the design method will be described later with reference to FIG. 5).

As a result, θ, aχo0 is the smallest when no is 00, and θ, aχ90' is the largest when no is 90°.As shown in Figure 2, the light distribution pattern is wide in the left and right direction and wide in the vertical direction. It gets narrower. No. 29 is set to have light distribution characteristics suitable for a headlamp for an automobile.

A central light condensing portion (hot zone) 14 is formed near the intersection 0 of the optical axis Z and the screen.

FIG. 3 is a plan view of the flefter 11, drawn in correspondence with FIG. 2 shown above, and lla is a light source bulb mounting hole.

The points L S v and Le are as described with reference to FIG.

The curve L that was arc-shaped in FIG. 1, which is a perspective view.
e-Ls has a straight line shape in FIG. 3 which is a plan view. The reason for this is that in FIG.
This is because ′ is perpendicular to the plane of the paper.

Ln shown in FIG. 3 is the length of the cut line Le-Ls, L
, represents the length to an arbitrary point.

The luminous flux shown in FIG. 3 and reflected by the flutter 11 forms the light distribution pattern shown in FIG. 2 on the screen.

Next, the correspondence between the position of the reflection point on the glue flapper 11 in FIG. 3 and the position where the reflected light reaches the light distribution pattern in FIG. 2 will be summarized and described again.

In FIG. 3, the light reflected at the outermost point Le on IV-IV reaches the central condenser 14 in FIG. 2.

In FIG. 3, the light reflected at the innermost point LS on the IV-IV edge line is the cut line 13 of the plane N in FIG.
It reaches the outermost point 13s of the upper light distribution area.

Distance Li from point LS on the IV-IV edge line in Figure 3
The light reflected at the point m, which is away by
In the above, a point m', which is away from the point 13s by an angle θ, is reached.

FIG. 4 shows the mV-IV cross section of FIG. 3 above.

Next, a method for determining the shape of the reflector 11 having such reflective performance in terms of design will be explained with reference to FIG.

This figure shows the above-mentioned plane Nn. The assumed orthogonal coordinates are depicted above, and the Z axis is the aforementioned optical axis.

The X' axis is a plane Nn that is orthogonal to the above two axes. This is the upper coordinate axis.

Point F is the coordinate origin and is the position where the point light source is placed.

In addition, as a practical problem, since a point light source cannot be used, it is sufficient to position the center of the light source (filament) at this point F.

Consider the point (X-work, 2□).

Arrow m is the optical path of light emitted from point light source F and incident on point (Xl, Zl), and D is its angle of incidence.

If the coordinates of the point (Xz+Zi) are given, the equation of the arrow m and the angle of incidence D1 can be easily determined.

Next, a desired reflection direction (arrow q) is arbitrarily set. This arrow q may be set so as to obtain a target light distribution pattern.

This determines the angle φ between the incident light indicated by the arrow m and the reflected light indicated by the arrow q.

Based on the above angle φ, find its bisector k.

Furthermore, a reflective surface 15 whose normal is the above-mentioned bisector k is determined.

Bl is the above reflective surface and surface N. . This is the Z-section of the line of intersection with .

Next, the reflective surface 16 passing through the point (X z + Z z ) is determined.

In this way, the minute reflective surfaces are sequentially determined, and the reflective surface of the glue flex 11 is determined as the envelope surface of these surfaces.

Performing this calculation by hand requires a great deal of time and effort, making it impractical; however, by using a computer, the calculation can be done quickly and easily, and the calculation according to the present invention can be carried out with practical economy. It can be implemented.

FIG. 1 above shows that the surface N in the present invention is at an arbitrary angular position n
' However, as special cases, the case where n=o° and the case where n=90° are illustrated as shown in FIG. 6.

The light is emitted from point F, and the optical axis Z is at the center of the right end of the reflector 11.
The reflected light beam of arrow 17r reflected parallel to
The reflected light beam of arrow 17Q reflected parallel to
The reflected light flux of arrow 17u that is reflected in parallel to
A central light condensing portion (hot zone) 14 is formed by concentrating at the center of the 8-throat light distribution pattern.

A vertical cross-sectional view of the reflector 11 is shown in FIG. However, since the glue flap 11 in this example is vertically symmetrical, only the upper half is drawn and the lower half is omitted.

Further, a horizontal cross section of the reflector 11 is shown in FIG.
Since the glue flaper 11 of this example is bilaterally symmetrical, only the right half is shown.

〔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 is formed by the light beam reflected by the reflector, so the front lens can be omitted or the front lens can be The lens configuration can be significantly simplified.

Furthermore, the desired light distribution pattern as described above can be obtained without being restricted by the outer contour of the reflector.

[Brief explanation of the drawing]

1 to 8 show an embodiment of the present invention, with FIG. 1 being a schematic perspective view, FIG. 2 being a plan view for explaining the light distribution pattern, and FIG. Plan view. Figure 4 is an explanatory diagram showing a cross-sectional view of the beam flap with the optical path added. Figure 5 is a diagram to explain the design method of the beam flap. Figure 6 is a schematic perspective view. Figure 7 is a vertical sectional view of the beam flap. , FIG. 8 is a horizontal sectional view as well. FIG. 9 to FIG. 11 are explanatory diagrams regarding the conventional technology. 12 to 14 are explanatory diagrams of the invention related to the earlier application, and FIG. 15 is an explanatory diagram of the problems in the invention related to the earlier application. 1... Parabolic mirror of revolution, 2... Prism lens, 3...
... Diffusing reflector, 4... Auxiliary spherical mirror, special concave mirror to which the present invention is applied, 8... Clear lens, 11...
-Reflector, 13... Cut of reflector by plane N, 14... Center light condensing part.

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, emitted from one point F on the Z axis, and then emitted from point L on the reflector
The reflected light of the light incident on is on the plane N including the above point L. b. The angle θ that the reflected light makes with the Z-axis is larger as it approaches the intersection of the reflector and the Z-axis, and smaller as it is farther from the intersection, and the reflected light in the periphery of the reflector is approximately parallel to the Z-axis. c. For each of many surfaces N whose angle with the vertical surface is n, when the maximum value of the angle that the reflected light makes with the Z axis is θmaxn, the larger the angle n of the surface N, the larger θmaxn is, and the smaller the angle n The closer the surface is to N, the smaller θmaxn is. However, the angle n is a variable.