JP2668306B2 - Vehicle headlight reflector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The reflector of a vehicle headlight according to the present invention is:
A light distribution pattern with reduced glare can be obtained while a cut line peculiar to a low beam is formed by effectively using the entire reflecting surface without providing a light shielding member.

[0002]

2. Description of the Related Art Recent trends in automobile design are driving the search for new headlamps, and as the shape of the vehicle body approaches a streamlined shape to meet the demands for high speed and high fuel efficiency. As a result, the front end of the vehicle is tilted toward the horizon, and under the influence of this, the outer lens of the headlamp is also tilted.

[0003] As a result, headlamps tend to have a smaller effective width in the vertical direction. The most basic configuration of an automotive headlamp for obtaining a low-beam light distribution conforming to the light distribution standard is to place a coil-shaped filament near the focal point of a rotating parabolic reflector with its central axis The arrangement is such that it is arranged along the optical axis of the reflecting mirror (so-called C8 type filament arrangement), the shade is arranged below the filament, and the outer lens for light distribution control is arranged in front of the reflecting mirror.

In this case, the cut line forms a shadow portion above the horizontal line on the side of the opposite lane in the projected image and above the boundary line inclined at a predetermined angle by partially blocking light by the shade. It is obtained by doing.

By the way, the outer lens is formed with a large number of lens steps that play a major role in the light distribution control. However, if the outer lens is steeply tilted, the light distribution control that has relied solely on the lens step is limited. There are two problems as a result.

That is, the tilted outer lens generally produces a curved light distribution pattern at the time of irradiation of the low beam, and as a result, the visibility on the road shoulder is deteriorated. One of the problems is that the outer lens has a vertical axis. When the angle formed with respect to the angle, the so-called slant angle, increases, the light drooping phenomenon (the phenomenon that the left and right ends of the light distribution pattern droop) due to the wide diffusion lens step formed on the outer lens becomes remarkable.

The second problem is that as the width of the reflecting mirror becomes narrower, the luminous flux decreases.
As a result, visibility at a distant place becomes insufficient.

Therefore, projector-type lamps have been used to overcome the above-mentioned restrictions.
In this projector type lamp, a shade is arranged in the vicinity of the second focus position of the elliptical reflecting mirror, and a sharp cut line is obtained as a result of the image of the shade being projected by the convex lens. There is.

However, in all of the above headlamp devices, since the shade is used to form the cut line, the cutoff ratio is high, but most of the light emitted from the filament is blocked by the shade. Therefore, there is a problem that the utilization rate of the luminous flux is low.

Therefore, in order to solve this problem, there is a strong tendency in recent years to pass the light distribution control function that has been imposed on the outer lens to the reflecting mirror.

The fact that a reflecting mirror having a light distribution control function is preferable is supported from the viewpoint of reducing the bonnet.

That is, for a vehicle body shape in which the height from the bumper to the end of the bonnet is not so high, a headlamp having a narrow upper and lower width is preferable. However, in this case, the utilization factor of the luminous flux still becomes a problem. That is, the method of forming a cut line by using a shade cannot effectively use a light beam, and thus it is not preferable to use a shade.

In this way, the idea of using the total reflection surface of the reflecting mirror and forming the cut line only by the shape of the reflecting mirror is born, and valves without shade (for example, # 9005 and # 9006). And H-1 bulbs), and a headlamp device in which a reflector is the mainstream of light distribution control emerges as a slant type and narrow headlamp candidate.

[0014]

However, in a headlamp device using a bulb without a shade, a sharp cut line is formed and a central luminous intensity of a light distribution pattern is ensured only by a reflection mirror, which is accompanied by glare. There was a problem that could not be realized without.

A simple method for forming a clear cut line without using a shade is to shift the upper half b and the lower half c of the parabolic reflector a back and forth as shown in FIG.
The focus Fb of the upper half b is located behind the filament d, and the focus Fc of the lower half c is located in front of the filament d. In the drawing, the x axis is selected as the optical axis, and z
The axis is selected as a vertical axis.

FIG. 25 shows a projected image e from the upper half b of the reflecting mirror a and a projected image f from the lower half c combined. In the drawings, “HH” indicates a horizontal line, and “VV” indicates a vertical line.

In such a reflecting mirror a, the upper half b
There is a disadvantage that a discontinuous step is generated between the upper and lower halves c, and glare occurs above the cut line g due to molding accuracy and non-uniformity of the reflective layer at the edge (FIG. 25).
Is indicated by the shaded area. ) Occurs.

As described above, it is difficult to solve the above-mentioned problem with the combination of the basic shapes known so far with respect to the shape of the reflecting mirror. Therefore, a mathematical reflecting curved surface based on a new design concept is desired. Was.

[0019]

In order to solve the above problems, the present invention employs the following curved surface as a basic surface of the reflecting surface.

The feature of the basic surface is that, first, a reference parabola is provided in a plane inclined at a predetermined angle with respect to a horizontal plane including the optical axis, and on the optical axis passing through the vertex and the focal point of the reference parabola. It has a reference point at a point different from the focal point with respect to the apex, and further, light reflected when the light assumed to originate from the reference point is reflected at any point on the parabola obtained by projecting the reference parabola on the horizontal plane. Has an optical axis parallel to the ray vector, and passes through an imaginary paraboloid of revolution passing through the reflection point and focusing on the reference point, and intersecting lines when cut along a plane parallel to the vertical axis including the ray vector. That is, the reflection surface is formed as an aggregate.

That is, the virtual paraboloid of revolution has a reference point deviated at a certain distance from the focal point of the reference parabola as a focal point, and when it is assumed that light is emitted from the focal point, the virtual paraboloid is moved to the horizontal plane of the reference parabola. Is a parabolic surface having an optical axis parallel to the ray vector of the light reflected at the reflection point on the orthographic projection and including the reflection point.

The virtual plane is a plane that includes the ray vector of the reflected light passing through the reflection point and is parallel to the vertical line.

The set of intersections of these virtual paraboloids and planes form the basic surface according to the present invention.

Here, the reflecting surface is divided into three reflecting area groups.

These reflection area groups have the following characteristics in terms of their shapes.

First, the first reflection area group or reflection area is close to a horizontal plane including the optical axis and approximates a paraboloid of revolution.
It has a curved shape .

The second reflection area group has a curved surface shape defined by a plane in which the reference parabola is inclined with respect to the horizontal plane at a cut line angle with respect to the above-mentioned basic surface. For a region located above, the reference point is located on the optical axis closer to the vertex than the focal position of the reference parabola, and for a region located below the horizontal plane containing the optical axis, the reference point is located at the vertex with respect to the focus of the reference parabola. It is located on the far side optical axis side.

[0028] The third reflective region group, Tadashi the horizontal plane including the optical axis plane including the reference parabola with respect to the basic surface
It has a fixed curved surface shape , of which the reference point of the area located above the horizontal plane including the optical axis is located on the optical axis near the apex of the focal point of the reference parabola and below the horizontal plane including the optical axis. The reference point of the located region is located on the optical axis far from the apex with respect to the focal point of the reference parabola.

The filament is arranged along the optical axis of the reflecting mirror with respect to such a reflecting surface, and is divided by the point having the largest point-to-point distance among the reference points related to the second and third reflecting area groups. An orthographic projection of the filament onto the optical axis is located within the range on the optical axis to be performed.

[0030]

In the basic surface according to the present invention, between the focal point of the reference parabola and the reference point deviated from the focal point, a filament is arranged along the optical axis passing through both points, and the orthogonal projection of the reference parabola onto the horizontal plane. Assuming that a projected image of the filament at an arbitrary point on the intersection of the virtual rotation paraboloid and the virtual plane assumed for each point above is projected on a distant screen, the projected image is horizontal according to the intersection. A point on the line (however, a point on the screen corresponding to the vertex of the reference parabola is excluded) is the center of rotation, and is arranged below the horizontal line and close to the horizontal line.

When the reflecting surface according to the present invention is composed of three types of reflecting area groups with respect to the optical axis as described above,
The filament image obtained by the first reflection region group (or reflection region) forms a prototype of a cut line inclined with respect to the horizontal line, and is located on one side with respect to the vertical plane including the optical axis and at least the second and The prototype of the horizontal cut line is formed by the cooperation of the regions belonging to the three reflection region groups. Furthermore, since the filament images can be collected in a limited area immediately below the horizontal line, a central area of brightness can be easily created with respect to the luminous intensity distribution.

Therefore, according to the present invention, the glare problem is eliminated by forming the reflection surface as a continuous curved surface, and the entire light reflection control function is effectively used without using a shade. A prototype of a projection pattern that contributes to the generation of a clear cut line can be created only by using only the light source, thereby reducing the burden on the outer lens involved in light distribution control and increasing the slant angle.

[0033]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of a reflector for a vehicle headlamp according to the present invention will be described below with reference to the illustrated embodiments.

Before discussing the specific shape of the reflective surface, we will start by discussing the basic principle that all filament images projected by any point on the reflective surface must be located below the cut line. The features of the reflecting surface will be outlined below.

First, in order to explain the basic concept in the present invention, the change of the projected image of the filament with respect to the change of the location on the reflection surface is different from the case where the conventional rotation parabolic reflection surface is used. The difference will be clarified by comparing the two.

FIG. 1 is a schematic front view when the reflection surface 1 is viewed from the optical axis (when this is selected as the x-axis, the x-axis extends in a direction perpendicular to the paper). An axis orthogonal to the x axis and extending in the horizontal direction is selected as the y axis, and an axis perpendicular to the x axis and extending in the vertical direction is selected as the z axis. The origin O of this orthogonal coordinate system is located at the center of the bulb mounting hole 2.

In the drawing, the angle θ between the plane including the line segment OC and the x axis and the y axis corresponds to the cut line angle, and this plane (where y <0) and the xy plane ( Where y
> 0) and two reflecting areas 3 above and below the reflecting surface 1,
Divide into 4 and think.

The upper reflective area 3 has a shape that forms a part of a paraboloid of revolution having a focal point at a point F shown in FIG. 2 (a point separated from the origin O by a distance f in the positive direction of the x-axis). ing.

In the case of a paraboloid of revolution, the lower reflecting area 4 is of course a part of a paraboloid of revolution, and in the case of a basic surface according to the present invention, it is a paraboloid of revolution. It has a slightly complicated shape based on.

First, the change of the projected image of the filament 5 with respect to the rotating parabolic mirror will be described.

In this case, the filament 5 having the C-8 structure is located between the point F and the point D (a point deviated from the point F by a distance d in the positive x-axis direction) as shown in FIG. Have been.

In order to make the direction of the filament 5 clear for convenience, the filament 5 has a conical pointed end on the point F side and a flat end on the point D side. The assumption is a pencil shape for the surface. "

Consider a rectangular area 6 indicated by a dashed line in FIG. 1, and a surface and a reflective surface which are located closer to the origin O in a region on the right side (that is, y> 0) and have a constant y coordinate. Considering five representative points on the line of intersection 7 with 1, how the filament image is projected on a screen located far from the reflecting surface 1 based on these points will be described.

Regarding the representative points on the intersection line 7, points P1, P2, P3, P4 and P5 are arranged in order from the one having the largest z coordinate.
It is assumed that the points P1 and P2 belong to the area 3, the point P3 is located on the y-axis, the points P4 and P5 belong to the area 4, and the points P1 and P5, and the points P2 and P4 have their z coordinates. Have opposite signs and their absolute values are equal to each other.

FIG. 3 shows that the points P1, P2, P3, P4, P4 are obtained when the reflecting surface 1 is in the form of a single paraboloid of revolution.
5 schematically shows the arrangement of filament images projected on a distant screen by 5.

I (X) in FIG. 3 shows a filament image by the representative point X shown in (), and in any case, the horizontal line H--H and the vertical line are shown although the size of the filament image is different. It is recognized that the filament image is arranged with the intersection HV with VV as the center of rotation. That is,
As the representative point changes from the top in the order of P1, P2, P3, P4, and P5, the filament image has a pointed end that always faces the point HV, as indicated by the arrow C, and the horizontal line H-. From below H, it rotates counterclockwise around point HV.

That is, if the area 4 has a parabolic shape like the area 3 and both of its focal points are at the point F, the image on the screen is radial with respect to the center HV as shown in FIG. And a series of filament images extending to

Since the filament image projected by the points belonging to the area 4 of the reflecting mirror is located above the horizontal line HH, as described above, in the headlamp apparatus using the parabolic reflecting mirror, the filament 5 By providing a shade below, this unnecessary portion is removed, and a projection pattern as shown in FIG. 5 is created.

By the way, if the contribution of the region 4 to the light distribution pattern is not blocked by a shade or the like, the region 4
It is necessary to devise to shift the filament image projected by the point belonging to the position so that it is arranged below the cut line.

That is, as shown in FIG. 6, the filament image projected by the points P4 and P5 in the area 4
If it turns around a point RC on the horizontal line HH separated by a certain distance from the center line, the surface shape of the area 4 satisfies the requirement that the filament image be arranged below the cut line.

FIG. 6 schematically shows the arrangement of filament images when the shape of the reflection area 3 is a paraboloid of revolution and the shape of the reflection area 4 is a curved surface according to the present invention. 3 is a schematic representation, and illustrates a filament image at each representative point on the intersection line 7.

In FIG. 6, J (X) indicates the arrangement of filament images corresponding to the respective representative points X shown in parentheses, and the filament images formed by the representative points P1, P2, and P3 are rotated in the area 3 in half. As is clear from the parabolic shape, it shows a change in rotation around the point HV,
The filament image by the representative points P4 and P5 is a horizontal line HH.
The arrangement is such that the upper point RC is the center of rotation.

That is, as the representative point is lowered from the top to P1 → P2 → P3, the filament image is rotated counterclockwise about the point HV from below the horizontal line H-H and then positioned on the horizontal line H-H. After that, the representative point further increased from P4 to P
As shown by arrow M, when the filament goes down to 5, it changes counterclockwise around the point RC and rotates below the horizontal line HH, and the flat end of the filament image is always at the point R.
It is located directly below the horizontal line H-H so that it faces C.

In this example, after the intersection line 7 is specified, the filament image is converted into the point R by the representative points belonging to the reflection area 4.
Although the manner of change is described with C as the center of rotation, if another line of intersection is selected, there is another center of rotation on the horizontal line H-H corresponding to the line of intersection.

Next, how to find an equation of a curved surface having such a characteristic regarding the arrangement of the filament images will be considered.

As shown in FIG. 7, let us consider a parabola 8 located on a horizontal xy plane and having a point F as a focal point.

Light 9 emitted from a point F near the rear end of the filament 5 is reflected at a point P3 on the parabola 8, and then emitted in a direction parallel to the optical axis (that is, the x-axis).

Further, the light emitted from the point D near the front end of the filament is reflected at the point P3, then emitted toward the point RC on the screen SCN arranged at a distant position, and the light ray 10 (that is, the light beam) intersecting the optical axis (that is, , And a vector P3_RC as a direction vector).

Now consider another parabola 11. This parabola 11 has an optical axis parallel to the vector P3_RC and has a point D as a focal point. In the figure, the parabola 1 is at the point P3.
It is inclined with respect to 1.

By rotating this parabola 11 about its optical axis, a paraboloid of revolution can be obtained, but by cutting this paraboloid of revolution with a plane containing the vector P3_RC and orthogonal to the xy plane. The resulting parabola is defined as a parabola 12.

By moving the point P3 along the parabola 8, a curved surface as an aggregate of the parabola 12 is generated.

This curved surface has focus points F and D, and when this is used for the reflection area 4, a sharp horizontal cut line can be obtained.

That is, in FIG. 7, the surface 1 is displayed at the stage where the filament image is projected on the screen SCN.
3, the image 14 by the point P3
Becomes parallel to the horizontal line, the image 15 formed by the point P5 forms an angle with the horizontal line, and the point P3 originating from the point D
Is reflected by another point P5 on the parabola 12 after being emitted from the point D and becomes parallel.

As described above, since the shape of the intersection line 8 is defined so that the light with respect to the flat ends of the filament images 14 and 15 is parallel, the point RC where these parallel lights coincide with each other in the distant position is the rotation center. As a result, filament images 17 and 18 (according to our notation, respectively correspond to J (P3) and J (P5)) are arranged.

As a result, as shown in FIG. 6, the filament image formed by the reflection area 4 is always located immediately below the horizontal line H-H with the point (excluding the point HV) located on the horizontal line H-H as the center of rotation. The original purpose of collecting and placing is achieved.

It is to be noted that the filament image 17 is exactly the horizontal line H.
In order to arrange it under -H, it is necessary to displace the filament 5 slightly above the optical axis.

The remaining work is to quantitatively express the reflection surface to be obtained by mathematical expressions, and to apply such a reflection surface to an actual reflecting mirror. Hereinafter, the description will be made in this order.

First, in order to facilitate understanding, the cut line peculiar to the passing beam is intentionally excluded from consideration, and the reflection area 3 has a half-divided rotation parabolic reflection area 3. A simplified model, which is assumed to be composed of two regions of the lower reflection region 4 to be obtained, will be described.

In this case, the following two conditions a) and b) are imposed on the shape of the reflection surface used for the reflection area 4.

A) Continuity condition: The shapes at the boundary with the reflection area 3 (that is, the cross section in the xy plane) match.

B) Arrangement condition of the filament image: The filament image by the reflection area 4 is arranged below the horizontal line HH and as close as possible to the horizontal line HH.

That is, in the former condition a), if there is a discontinuity between the reflection region 3 and the reflection region 4, glare is generated due to the discontinuity, so that it is necessary to prevent this. The latter condition b) is a condition necessary for effectively utilizing the reflected light from the reflection area 4 as light that contributes to the light distribution pattern without being blocked by a shade or the like.

The condition b) can be expressed as follows by analyzing the situation described with reference to FIG. 7 in more detail.

That is, the fact that the filament image is arranged on the horizontal line H-H with the point other than the point HV as the center of rotation means that the light after the light from the point D is reflected at the point on the parabola 8 is parallel. This is equivalent to the fact that this relationship holds for each arbitrary intersection line.

FIG. 8 shows this situation.

A point P in the figure indicates an arbitrary point located on the parabola 8 in the xy plane. If the light emitted from the point F is reflected at the point P, the reflected light 19 becomes the x-axis. Go straight in parallel with (the direction of travel is indicated by vector PS).

The light 20 reflected from the point P after the point D is reflected at a smaller angle of reflection than the light 19 according to the law of reflection, and at a certain angle with respect to the light 19 (this is referred to as “α”). The vehicle goes straight (the traveling direction is indicated by a vector PM).

Now, consider a virtual paraboloid of revolution 21 (indicated by a two-dot chain line) having a point D as a focal point, an optical axis passing through the point P and parallel to the ray vector PM.
Sectional shape when the paraboloid 21 is cut by a plane including M and parallel to the z-axis (this is described as “π1”) (that is, the intersection line 22 between the paraboloid 21 and the plane π1) think about.

The cross-sectional shape (indicated by a broken line) is of course parabolic. However, after being emitted from the point D, light reflected at an arbitrary point on the intersection line 22 is parallel to each other. This is in agreement with the situation shown in FIG. 7 regarding the situation that the relationship of "existence" is established.

Thus, the intersection of the virtual paraboloid corresponding to each point P on the parabola 8 and the plane parallel to the optical axis of the virtual paraboloid and parallel to the z-axis passing through the point P The set of lines is the desired reflecting surface.

In the following, this curved surface is obtained in an expression form by parameter display using the parameters shown in [Table 1].

[0082]

[Table 1]

FIG. 9 is an xy plane cut at z = 0.
Then, an arbitrary point P on the parabola 8 is P
(Q^Two / F, -2q, 0) (x =
q^TwoIf q is eliminated from the two expressions of / f and y = -2q, y^Two= 4
fx is obtained. 9 to 1
The definition of each coordinate point in 1 is shown in [Table 2].

[0084]

[Table 2]

FIGS. 10 and 11 are schematic perspective views for explaining the geometric relationship in obtaining the expression of the reflection surface to be obtained. FIG. 10 and FIG. The definition is shown in [Table 3].

[0086]

[Table 3]

Now, in order to derive the expression of the reflection surface, a vector EP parallel to the ray vector PM is obtained, and a point B on the intersection of the above-mentioned virtual paraboloid 21 and the plane π 1 at the point P is obtained.
May be obtained for the case where the z coordinate is represented by the parameter h.

To obtain the vector EP, the point E
Knowing the coordinates of is a priori, and for this we use the following geometrical relationship:

In other words, in FIG.
If the reflection angle of the light reflected at the point is φ (that is, 法 FPn, where n is the normal direction at the point P), the straight line JP is parallel to the x-axis, and the point N is within the line segment JF. Focusing on the geometrical property of the parabola that the straight line F′J is the direct line of the parabola 8 and the length of the line segment FP and the length of the line segment JP are equal, the rhombus PFP′J is Four congruent triangles ΔN by line segment FJ and line segment PP ′
FP, ΔNJP, ΔNJP ′, and ΔNFP ′.

Thus, the coordinates of the point E symmetrical to the point D with respect to the tangent PN (or PP ') of the parabola 8 at the point P are parallel to the straight line 23 passing through the points J and P' and the vector NF passing through the point D. Can be obtained as the coordinates of the intersection with the straight line 24.

Since the vector EP is obtained from the coordinates of the points P and E, the operation of obtaining the coordinates of the point B on the intersection line 22 between the virtual paraboloid 21 having an optical axis parallel to the vector EP and the plane π1 is next performed. Move on to.

Here, the expression of the virtual paraboloid 21 is not explicitly obtained (the virtual paraboloid is a surface used in the thinking process, and it is not very meaningful to express its shape concretely by an expression). Is not found), and the coordinate value of the point B is calculated.

Now, consider a point H deviated from the point E by a distance h in a direction parallel to the z-axis as shown in FIG.
Consider a straight line 25 passing through a point B (z _b = h) on 2.

The parabola 22 is an intersection line when the virtual paraboloid 21 is cut by the plane π1, and therefore the distance from the point B to the foot H of the perpendicular line hung on the quasi-line EH, and the point B and the virtual paraboloid. The distance of 21 to the focus D should be equal (this is due to the geometry of the paraboloid of revolution).

That is, since the vertex on the isosceles triangle HBD in which the length of the line segment HB is equal to the length of the line segment BD is the point B to be determined, as shown in FIG. plane perpendicular to the midpoint _{F C} minute HD as vector HD [pi
It suffices to calculate the coordinates of the intersection of 3 and the straight line 25.

The point F _C is easily obtained from the midpoint of the line segment HD, and the vector HD is obtained from the coordinates of the points H and D.

Therefore, the plane π3 passes through the point F _C and is expressed by a plane equation using the vector HD as a normal vector, and the straight line 25 is a point h away from the point P in a direction parallel to the z-axis. since the U _P street vector EP represented by the formula of the straight line and the direction vector, it is simultaneous both expressions x,
When y is solved, the parameter Q is replaced and rearranged, the coordinates of the point B are finally obtained as shown in [Equation 1].

[0098]

(Equation 1)

The formula in the process of deriving [Formula 1] has been omitted for the sake of simplicity of description. Can only be obtained with knowledge.

[0100] is a formula of [Expression 1] reflecting surface expression is wanted, in this equation, looking at the d = 0 to _{attempt, x b = q ^ 2 /} f + h ^ 2 / 4f, y b = −2q is immediately obtained, and when the substitution of h → z, x _b → x, y _b → y is performed and the parameter q is eliminated, the expression of the paraboloid of revolution is eventually obtained.

That is, it can be seen that the expression [1] includes the paraboloid of revolution as a special case of d = 0. It should be noted that the continuity condition a) described above is satisfied by [Equation 1].
If h = 0 is set in the equation, it can be easily confirmed from the equation of the parabola 8 because h = 0.

In the above discussion, the formation of the cut line has been described without touching it. However, in the following, a specific design guideline for the reflection surface considering the cut line specific to the low beam is given. I will decide.

The first thing that comes to mind is to divide the reflecting surface 1 into three regions as shown in FIG. That is, the radian angle method (the angle between the y-axis and the y-axis, which increases counterclockwise when viewed from the positive direction of the x-axis to the negative direction, starting from the positive axis of the y-axis around the x-axis). The reflection surface 1 is divided into three regions 3 ₁ , 4 ₁ and 4 ₂ for consideration.

[0104] In case the cut line angle θ is 15 °, areas 3 ₁ are parabolic region occupied an angular range of 195 ° from 0 °, the region 4 ₁ Number [with a cut line angle with respect to the optical axis 1] which is obtained by rotating the curved surface of the formula
It occupies an angular range from 5 ° to 277.5 °.

[0105] the remaining region _{4 2} is used as it is without rotating the Expression 1 of the curved surface, 360 ° from 277.5 °
Occupies the angle range.

The characteristics of such a reflecting mirror are as follows.

1. The light distribution pattern consists of three grouped filament images, each of which is arranged around a different center of rotation. That is, the filament image of a region 3 is rotated around the point HV, filament image of a region 4 ₁ rotates about a point on the 15 ° cut line, the filament image of a region 4 ₂ points on the horizontal cut line Rotate around.

2. A set of regions 4 ₁ and 4 ₂ intersection of the inflection point, whereby occurs a discontinuous shift of the filament image along the boundary therebetween.

In order to reduce glare in this reflector, light must be diffused over a certain range.
Simply diffusing the light in the horizontal direction by the outer lens results in that the area under the horizontal cut line located on the opposite lane side in the light distribution pattern becomes relatively dark.

To correct this, the following modification is required on the reflecting surface.

[0111] Part 1 is to "region 3 ₁ and 4 ₁ and filament image when exceeded downwards boundaries must drastically moves to be positioned below the horizontal line.".

FIG. 13 shows the representative points on the line of intersection 26 between the reflecting surface and the y = constant plane, and the point P_
1, P_2, P_3, P_4, P_5, When P_6, point P_1, point P_2, point P_3 belongs to the area _{3 1,}
Point P_4, P_5, P_6 belongs to the region _{4 1.} The point P_3 and the point P_4 are located immediately near the boundary OC.

FIG. 14 schematically shows the arrangement of the filament images at these representative points. J (X) represents the filament image at the representative points X. As the representative point goes down from the point P_1 to the point P_2 to the point P_3, the filament image moves clockwise around the point HV as a center of rotation. When the filament image moves to the point P_5 beyond the boundary line OC, the filament image J (P_4) becomes It descends suddenly and is located immediately below the horizontal line HH.

[0114] Part 2 of the modification, the rotation center regarding filament images projected by the region 4 ₁ "reflector as shown in FIG. 14, that it is perpendicular foot from the point RU to the horizontal line H-H RL It is located in. "

That is, in FIG. 14, points P_4, P_5,
Filament images J (P_4) and J (P_
5) and J (P_6) define the shape of the reflection surface so that the point RL on the horizontal line H-H is arranged as the center of rotation.

In order to obtain the thus-corrected reflection surface equation, the above-mentioned parabola 8 is rotated about the optical axis at an angle of the cut line angle θ from the horizontal line, and the equation [1] is used. The same procedure as in the derivation process may be used.

FIG. 15 and FIG. 16 are explanatory diagrams at the working stage in obtaining the expression of the reflection surface. The meanings of points F, D, and F 'in FIG. 15 are as described in [Table 2]. is there. The plane π0 is a plane that includes the x-axis and is inclined by the cut line angle θ with respect to the xy plane.
A point on the parabola 27 having the point F as a focal point is a point P ^*.
It is.

An axis that forms an angle of θ with the y axis on the plane π0 is selected as the Θ axis, and the distance between the point N ^* on the Θ axis and the origin O is selected as the parameter q. 9 is different from FIG. That is, in FIG. 9, the parabola 8 on the xy plane is used as a reference, whereas in FIG. 15, the parabola 27 on the plane π0 is orthogonally projected onto the xy plane. Therefore, among the points shown in [Table 2], those having the same meaning except for the difference in the plane being considered will be used by adding " ^* " to the upper right of the symbol representing this.

The definitions of each point are shown in [Table 4].

[0120]

[Table 4]

The expression for the reflecting surface can be obtained by the same procedure as that used to previously obtain the expression [1], based on the points obtained by orthogonally projecting each point on the plane π0 onto the xy plane. That is, a virtual paraboloid of revolution having a focal point D and passing through the point P ^* _U and parallel to the vector E ^* _U P ^* _U is defined as a vector E ^* _U.
The cross-sectional shape when cut along a plane π1 ^* that includes P ^* _U and is parallel to the z-axis, that is, the coordinates of the point B ^* on the parabolic intersection line 28 is calculated using the geometrical properties related to the rotating paraboloid. Straight line H
^* B ^* and plane π3 ^* (vector H ^* D at point F ^* _C)
May be obtained as an intersection with a plane having a normal vector.

In this case, the distance between the point N ^* _U and the origin O is represented by r
Then, r = qcos θ, and the straight line F′J
^* Is the directrix of the parabola 27, the length of the line segment FP ^* from the geometric properties of the parabola and the line segment J ^* P ^* length of note will be equal, and the point D with respect to the straight line P ^* N ^* The coordinates of the point E ^* are obtained as symmetric points.

Therefore, since the coordinates of the points E ^* _U and H ^* are known and the coordinates of the midpoint F ^* _C of the line segment H ^* D are obtained,
Since the plane π3 ^* is a plane having the vector H ^* D as a normal vector at the point F ^* _C , it can be represented by using the parameter Q.

[0124] A straight line ^H * ^{B *} because the formula of the straight line and the direction vector a vector ^E _{* U} ^P _* U at point U, simultaneous with the formula and the line ^H * ^{B *} of Formula plane Pai3 ^* Let it be solved (I omit the details of the calculation), x ^* _b
By rearranging by replacing → x, y ^* _b → y, z ^* _b → z, the expression [Formula 2] of the reflecting surface is finally obtained.

[0125]

(Equation 2)

Incidentally, it is clear that θ = 0, that this equation 2 is a generalization of the equation 1.

In application to an actual reflecting mirror, six reflecting areas 29A, 29B, 29C, 29D and 29 are used as shown in FIG. 17 with such a curved surface as a basic surface.
E, 29F.

[0128] In the figure, theta _a central angle of reflection area 29A, theta
_d indicates the central angle of the reflection area 29D.

Further, as shown in FIG. 18, the filament 5 is arranged with its central axis displaced slightly above the optical axis, and the three focal points E, F and D are arranged in this order from the side closer to the origin O. It is arranged on the optical axis.

“D _U ” is the difference between the x coordinates of the focal points E and F,
“D _D ” represents the difference between the x-coordinates of the focal points D and F, respectively. Since these positive and negative signs are selected to coincide with the positive and negative signs on the x-axis, d _U is a negative value and d _D Is a positive value.

In FIG. 18, the focal length f = 25.0.
(Mm), d _U = −3.8 (mm), d _D = 3.8 (m
m) and d _D −d _U = 7.6 (mm), the filament 5 has a cylindrical shape with a diameter of 1 mm and a length of 5 mm, and the center is the point C.

Table 5 shows the coordinates of each point.

[0133]

[Table 5]

Region 2 occupying the angle range from 0 ° to θ _a °
9A and the region 29D occupying the angle range from 180 ° to 180 ° + θ _d ° both have a paraboloid of revolution with the point F as the focal point.

The region 29C occupying an angle range of 90 ° to 180 ° and the region 29F occupying an angle range of 270 ° to 360 ° can be rotated around the optical axis by setting θ = 0 in the equation (2). It is a special curved surface that does not involve any operation, and d = d _U (<0) for the region 29C,
For the area 29F, d = d _D (> 0).

The area 29B occupying the angle range from θ _a゜ to 90 ° is a curved surface that has been rotated around the optical axis as θ = θ _{a in the} equation (2), and d = d
_U (<0).

[0137] regions 29E which occupies 270 ° angle range of 180 ° + theta _d DEG, and theta = theta _d in [Expression 2] where
Then, the curved surface is rotated around the optical axis , and d = d
_D (> 0).

The parameters for determining the curved surface shape of the above area are shown in a table format in [Table 6].

[0139]

[Table 6]

FIG. 19 schematically shows a composite pattern 30 of the filament image by the above-mentioned reflecting surface, and the range 31 having a shape similar to the side shape of the tetrapot is relatively relatively compared with other parts. It is a bright place.

It should be noted that the area 29A and the area 29 in the reflection area
The projection pattern by D contributes to the formation of a pattern that finally becomes an inclined cut line, and the regions 29A and 29
The projected patterns of B, 29D, and 29F finally contribute to the formation of horizontal cut lines.

The pattern shown in FIG. 19 is a source of the final light distribution pattern, and it is necessary to further expand the pattern in the horizontal direction. The outer lens provided in front of the reflecting mirror is required. As the inclination of No. 1 becomes remarkable, it becomes impossible to form a lens step having a large horizontal diffusing effect with respect to the outer lens, so that it becomes necessary to pass the diffusing effect to the reflecting mirror.

Therefore, by combining a set of equations representing a wavy pattern and the above-described series of equations relating to the reflecting surface, the reflecting surface is smoothly wavy and light is diffused only by the function of the reflecting mirror. .

For that purpose, the following function is defined.

[0145]

(Equation 3)

In the normal distribution type (or Gaussian type) function Aten (s, W) using the parameters s and W, the parameter W defines the degree of attenuation, and the shape represented by this function is shown in FIG. .

Then, consider a periodic function WAVE (s, λ) using the parameter λ as shown in [Equation 4].

[0148]

(Equation 4)

The parameter λ represents the wavelength of the cosine wave, that is, the interval between the waves, and the shape represented by the function is shown in FIG. In this example, the cos function is used as the periodic function, but various periodic functions may be used if necessary.

By multiplying these functions, an attenuating periodic function Damp as shown in FIG. 22 can be obtained. Therefore, based on this function, the above regions 29A to 29A are used.
Function Da defined in Table 7 below for each surface equation for F
When mp is added, wavy unevenness is added to the reflecting surface.

[0151]

[Table 7]

H is a parameter representing the maximum amplitude of the wave,
δ is a parameter indicating that the closer the value is to 1, the closer to a circular wave. For H, about 1/50 of the focal length f
The degree is a guideline, and if this value is too large, the cut line becomes unclear. Therefore, when adjusting the degree of diffusion, it is preferable to appropriately change the value of the wavelength λ.

As for θ _a and θ _d , either one of them may be set to a value equal to the cut line angle.
The region 29A may be made unnecessary by setting θ _a = 0 ° and θ _d = 15 °.

By changing the values of these parameters and the various parameters already described on a computer simulation, the reflection is achieved by repeating the trial so that the overall arrangement of the filament image is appropriate for the light distribution reference. The optical design of the surface is performed.

In the function Damp, the wave shape is bent at the boundary between the regions 29A and 29B or at the boundary between the regions 29D and 29E. There is no place.

FIG. 23 schematically shows the finally obtained light distribution pattern 32. A large filament image obtained by the central portion of the reflecting mirror is diffused in a wide angle in the horizontal direction, and the periphery of the reflecting mirror is There is a tendency for the small filament images obtained by the parts to be collected in the central area 33 of the light distribution pattern to form a part having the maximum brightness.

The outer lens arranged in front of such a reflecting mirror only needs to be provided with the minimum necessary lens steps, and in some cases, it may be a completely transparent lens.

Finally, the characteristics of the curved surface parameters (f, d _U , d _D , θ _a , θ _d, etc.) relating to the basic reflecting surface of the present invention are summarized in the following items. (1) If f is equal to the whole area of the reflecting surface, the reflecting surface is continuous. (2) Inflection occurs at the boundary between regions where the value of θ changes discontinuously. (3) The region where d = 0 has a parabolic shape. (4) Any focal point of the area is arranged on the optical axis, and the focal point of the area located on the upper side with respect to the horizontal plane including the optical axis is located near the apex O with respect to the focal point F (d _U <0),
The focal point of the region located on the lower side is located on the side opposite to the apex (d _D > 0) with respect to the focal point F. The filament does not have to be arranged with its central axis along the optical axis,
The orthographic projection of the filament onto the optical axis needs to be located within the range of the most distant focal points. (5) The parabolic area close to the horizontal plane including the optical axis is
When viewed from the front, they occupy the angle ranges θ _a and θ _d centered on the vertex O. At least one of these angles may be defined as the cut line angle.

By selecting such surface parameters,
According to the above characteristics, it is possible to obtain a reflecting surface whose light distribution control function is divided around the optical axis.

In order to diffuse the projection pattern obtained by this reflecting surface by the action of only the reflecting surface,
A wavy pattern is synthesized on the reflecting surface.

The parameters at this time are H, W, λ, δ, etc., but since the amplitude H of the wave is too sensitive to the clarity of the cut line, the wavelength λ is more suitable for adjusting the degree of diffusion. Easy to control.

[0162]

As is apparent from the above description, according to the present invention, the reflecting surface is composed of the three types of reflecting region groups as described above with respect to the optical axis, and the first reflecting region group (or (Reflection area) forms a prototype of a cut line inclined with respect to the horizontal line by the filament image obtained by the reflection area, and is located on one side with respect to the vertical plane including the optical axis, and at least belongs to the second and third reflection area groups. Not only is it possible to form the prototype of the horizontal cut line by synergy, but also to collect the filament image in a limited area directly below the horizontal line, thus creating a central area of brightness related to the luminous intensity distribution It becomes easier.

Therefore, by forming the reflecting surface as a continuous curved surface, it is possible to obtain a reflecting surface that does not require a shade without bothering the glare problem, and the sharpness is obtained only by the light distribution control action of the reflecting surface. It is possible to create a prototype of a projected pattern that contributes to the generation of various cut lines.

Then, as means for imparting a diffusing action in the horizontal direction to the reflecting surface, an attenuating periodic function given by the product of the normal distribution type function and the periodic function is added to the expression of the reflecting surface. By making the entire reflecting surface wavy, light can be diffused in the horizontal direction only by the action of the reflecting surface.

In this way, it is possible to reduce the dependence of the outer lens on the light distribution control and design a reflecting mirror suitable for a lamp with a large slant angle.

In the above-described embodiment, the description has been made mainly on the reflecting mirror having a circular front shape. However, all the embodiments without departing from the gist of the present invention, such as application to a square reflecting mirror, are described. Included within the technical scope of the invention.

[Brief description of the drawings]

FIG. 1 is a schematic front view of a reflection surface.

FIG. 2 is a schematic diagram showing an arrangement of filaments.

3 is a diagram showing an arrangement of a filament image projected by a representative point on an intersection line 7 in FIG. 1 when the reflection surface has a paraboloid of revolution shape.

FIG. 4 is a diagram showing a radial arrangement of filament images projected by a parabolic reflector.

FIG. 5 is a layout diagram of a filament image showing a state in which a cut line is formed by partially masking the filament image of FIG. 4 by a shade;

6 is an arrangement of filament images projected by representative points on an intersection line 7 in FIG. 1 in the case where the upper half surface of the reflecting surface has a paraboloid of revolution and the lower half surface has the basic surface shape of the present invention. FIG.

FIG. 7 is an optical path diagram relating to the basic surface of the present invention.

FIG. 8 is a schematic perspective view for explaining a basic surface of the present invention.

FIG. 9 is an xy plan view showing a process of deriving an expression for a basic surface of the present invention.

FIG. 10 is a perspective view showing a process of deriving an expression for the basic aspect of the present invention.

FIG. 11 is a schematic perspective view showing a geometric relationship between an isosceles triangle ΔHBD and planes π3 and π1.

FIG. 12 is a front view showing a configuration of a reflective surface on which a cut line can be formed, which can be easily considered in a thinking process.

FIG. 13 is a front view showing a representative point on the intersection line of the reflection surface.

FIG. 14 is a diagram showing the arrangement of filament images by the respective representative points in FIG.

FIG. 15 is an explanatory diagram (mainly showing the orthogonal projection from the π0 plane to the horizontal plane) at the work step of obtaining an expression for the basic reflection surface of the present invention in consideration of rotation about the optical axis.

FIG. 16 is an explanatory diagram at a work stage for obtaining an expression for the basic reflecting surface of the present invention in which the rotation about the optical axis is taken into consideration (mainly how to find a point B ^* on the reflecting surface based on the orthogonal projection to the horizontal plane). Is shown).

FIG. 17 is a front view showing a configuration of a reflection surface according to the present invention.

FIG. 18 is a schematic diagram showing a positional relationship between a filament and a focal point.

19 is a diagram schematically showing a projection pattern obtained by the reflecting surface of FIG.

FIG. 20 is a graph diagram schematically showing a normal distribution function Aten (s, W).

FIG. 21 is a graph diagram schematically showing the periodic function WAVE (s, λ).

FIG. 22 is a graph diagram schematically showing an attenuation periodic function Damp (s, λ).

FIG. 23 is a diagram showing an outline of a light distribution pattern.

FIG. 24 is a schematic diagram showing a configuration of a reflecting mirror in which a paraboloid of revolution is divided into two and the focal position of each reflecting surface is shifted.

25 is a diagram schematically showing a projection pattern by the reflecting mirror of FIG.

[Explanation of symbols]

Reference Signs List 1 reflection surface x optical axis 5 filament π0 inclined plane 27 reference parabola O vertex F focus D reference point P ^* _U reflection point π1 ^* plane 28 intersection line 29A, 29D first reflection area group 29B, 29E second reflection Area group 29C, 29F Third reflection area group D 29E, reference point for 29F Reference point for E 29B, 29C

Claims (2)

(57) [Claims] A basic surface of a reflector of a vehicular headlamp capable of forming a low beam has a reference parabola in a plane generally inclined at a predetermined angle with respect to a horizontal plane including an optical axis. On the optical axis passing through the vertex and the focal point of the reference parabola and having a reference point at a point different from the focal point with respect to the vertex, the light assumed to be emitted from the reference point is a parabola that projects the reference parabola to the horizontal plane. A virtual paraboloid of revolution having an optical axis parallel to the ray vector of the reflected light when reflected at any point of A reflector for a vehicle headlamp in which a curved surface is formed as an aggregate of intersection lines when cut by a plane parallel to an axis, wherein (a) the reflecting surface is divided into three reflecting region groups. Rukoto, (b) a first reflective area group or the reflection area, the optical axis Close to the free horizontal surface, it forms a curved shape similar to the paraboloid, (c) a second reflective region group, cut line angle plane to the horizontal plane including the reference parabola with respect to the basic surface Has a curved surface defined by an inclined surface with the reference point thereof located on the optical axis closer to the vertex than the focal position of the reference parabola for an area located above the horizontal plane including the optical axis, including the optical axis The reference point of the region located below the horizontal plane is located on the optical axis side farther from the apex with respect to the focal point of the reference parabola. (D) The third reflection region group defines the reference parabola with respect to the basic surface shape. A curve defined by a horizontal plane containing the optical axis
None the surface shape, of which the reference point for the region located above the horizontal plane including the optical axis is positioned on the optical axis of the vertex closer than the focal position of the reference parabola, located below the horizontal plane including the optical axis region The reference point is located on the optical axis far from the apex with respect to the focal point of the reference parabola, and (e) the filament is arranged along the optical axis of the reflecting mirror, and the second and third reflecting region groups Wherein the orthogonal projection of the filament onto the optical axis is located within the range on the optical axis which is divided by the point having the largest point-to-point distance among the reference points according to the above. mirror. 2. The reflector for a vehicle headlamp according to claim 1, wherein a function consisting of a product of a normal distribution type function and a periodic function is added to the expression of the reflecting surface for each reflecting area group. As a result, when viewed from a direction parallel to the optical axis of the reflecting surface, the difference in the undulations becomes larger closer to the center of the reflecting surface, forming a wavy reflecting surface that enhances the light diffusion effect in the horizontal direction. A reflector for a vehicle headlamp.