JPH0650107U - Projector headlight - Google Patents

Abstract

(57) [Abstract] [Purpose] To prevent color stripes caused by chromatic aberration from being conspicuous on a light distribution pattern in a projection lens that constitutes a projector-type headlight. A projector type headlamp 1 condenses light reflected by a reflecting surface 3 near an upper edge of a light shielding plate 5 arranged near a second focal point F2 of the reflecting surface, and defines a pattern image having a cut line. Then, the image is projected through the projection lens 8. When the projection lens 8 is viewed from the front, the focus Fu of the upper region 10
(Rear focal length = Bfu) is located at the front edge of the upper edge of the light shielding plate 5, and the focus Fd of the lower region 11 (rear focal length = Bfd)
(≧ Bfu)) is located below the focal point Fu, and both regions 1
A quadric surface area 9 is provided as a boundary area between 0 and 11. The blue light emitted from the focal point Fu and passing through the lower region 11 is bent downward and directed below the cut line.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The projector-type headlight of the present invention is intended to provide a novel projector-type headlight for the purpose of suppressing color stripes caused by chromatic aberration of a projection lens and horizontally diffusing a light distribution pattern by the lens.

[0002]

[Prior art]

 A projector-type headlight that uses the image projection principle of a projector is known as a vehicle headlight, and has advantages such as a small diameter, excellent light distribution characteristics, and a wide and even distribution of hot zones. .

FIG. 11 schematically shows the structure of a projector-type headlight.

The projector-type headlight a is a light that is reflected by an elliptical reflecting mirror c among lights emitted from a light source b, and is slightly displaced in the front-back direction from the upper edge of the light shielding plate d. After condensing light at a near position and cutting a predetermined light, the projection lens e arranged in the front projects the inverted image of the light shielding plate d to a distant position, which is peculiar to the passing beam. A cut line (or cut-off line) is formed. The LL line indicated by the alternate long and short dash line in the figure is the optical axis.

The projection lens e has a flat surface on the light source side and an emission surface that is generally aspherical, and its focal point is located near the upper edge of the light shielding plate d.

FIG. 12 shows the front shape of the projection lens e. The projection lens e passes through an intersection point O of the RH-LH axis extending in the horizontal direction and the UV-DV axis extending in the vertical direction and is orthogonal to them. It is rotationally symmetric with respect to an optical axis L-L extending in the front-rear direction (axis perpendicular to the paper surface) and has a single focal point.

[0007]

[Problems to be solved by the device]

 By the way, as a problem of the projector type headlight as described above, the light deviated from the paraxial region is dispersed due to the chromatic aberration of the projection lens e, and a rainbow pattern appears in the vicinity of the cut line, which reduces the visibility. It is known to invite.

This is because as shown in FIG. 11, the light incident on the peripheral portion of the projection lens e undergoes a spectral phenomenon due to the chromatic aberration of the lens, and the blue light lb is refracted more toward the optical axis side than the red light lr. As a result, color stripes are generated near the cut line, and when the vehicle is pitched (swaying in the front-back direction), the headlight light takes on a tint. Road users (oncoming drivers and pedestrians) because the headlight light changes color red or blue depending on the viewing angle. There is a problem such as causing inconvenience such as giving discomfort and dazzling.

As shown by the shaded area in FIG. 12, a blue difference is conspicuous in a region g near the lower edge of the lens, and a red aberration is noticeable in a region f near the upper edge of the lens, but particularly blue. Since chromatic aberration is more unnatural, it is necessary to improve the shape of the lower half of the lens.

[0010]

[Means for Solving the Problems]

 Therefore, in order to solve the above-mentioned problems, the present invention arranges a light source at the first focus position of the reflecting mirror, collects reflected light at the second focus position of the reflecting mirror, and In a projector-type headlamp configured to project a pattern image through a front projection lens after limiting the cut line by a light-shielding plate arranged so that its upper edge is located in the vicinity, The emission surface of the first area, which is located so as to extend in the horizontal direction at the substantially center, is formed into a quadric surface, and the focus of the second area, which is located above the first area, is set on the shading plate. The rear focal length of the third region, which is located near the upper edge and below the first region, is equal to or greater than the rear focal length of the second region, and the focus of the third region is It is located below the focal point of area 2.

[0011]

[Action]

 According to the present invention, the focal positions of the upper part and the lower part of the lens are shifted in the vertical plane, and the rear focal length of the lower part is designed to be equal to or larger than the rear focal length of the upper part. Light that passes through the front edge of the upper edge of the shading plate and passes through the lower part of the lens can be controlled to be downward light, and chromatic aberration can be reduced by directing blue light below the cut line. .

[0012]

【Example】

 Hereinafter, a projector type headlight according to the present invention will be described with reference to the illustrated embodiments.

1 to 5 show a first embodiment of the present invention.

As shown in FIG. 3, the projector-type headlamp 1 has a configuration in which a light-shielding plate is arranged in front of the reflecting mirror and a projection lens is arranged in front of it.

In the figure, reference numeral 2 denotes an elliptical reflecting mirror, which has a reflecting surface 3 having a shape in which a spheroidal surface around the optical axis (LL) is roughly cut in the optical axis direction. Therefore, the reflecting surface 3 has an inner first focal point F1 and an outer second focal point F2.

Reference numeral 4 denotes a coil-shaped filament, which is arranged such that its central axis is along the optical axis L-L of the reflecting surface 3 and whose substantially center is located at the first focal point F 1 of the reflecting surface 3. is doing. Therefore, the light emitted from the filament 4 and then reflected by the reflecting surface 3 is focused on the second focal point F2 and then spreads forward.

Reference numeral 5 denotes a light shielding plate having a curved shape facing forward, arranged so as to cross the optical axis L-L of the reflecting surface 3, and the height of the upper end edge 6 of the light shielding plate 5 is the optical axis L-. It is close to the horizontal plane containing L. When the upper edge 6 is bisected by a vertical plane including the optical axis L-L, the height of the upper edge on one side is slightly lower than the upper edge on the other side, and the optical axis L connecting the two is connected. A slope 7 is formed near -L.

The second focal point F2 of the reflecting surface 3 is located on the optical axis L-L, which is slightly toward the front from the center right above the upper edge 6 of the light shielding plate 5 in the left-right direction, that is, at the front end of the upper edge 6. ing.

Reference numeral 8 denotes a projection lens arranged in front of the light shielding plate 5, and is a convex plano lens having a flat surface on the light shielding plate 5 side (that is, the first curved surface on the incident side is a flat surface and the second curved surface on the emission side is a second surface). The curved surface is convex.) Is used.

FIG. 1 is a front view of the projection lens 8, which is aligned with the optical axis L-L along the z-axis (in FIG. 1, the axis is perpendicular to the paper surface and the direction toward the light source is the positive direction). An axis extending orthogonally in the horizontal direction is defined as an x-axis (the right side is the positive direction), and an axis extending in the vertical direction orthogonal to the x-axis is a y-axis (the upward direction is the positive direction). The coordinate system is set so that the origins of these orthogonal coordinate axes coincide with the vertex O of the projection lens 8.

The projection lens 8 is divided into three regions with respect to the focal length, has a non-rotationally symmetric shape with respect to the optical axis, and its peripheral portion 8a is a lens mounting portion.

The rectangular area 9 extending horizontally along the x-axis is a quadric surface area, and the cross section in the xz plane is a quadratic curve, and the cross section in the yz plane is linear. It has the shape of

Regions 10 and 11 are respectively located above and below the quadric surface region 9, and the focal position of the lens portion belonging to the upper region 10 and the focal position of the lens portion belonging to the lower region 11 are different. There is.

The lens portion of the upper region 10 is an aspherical lens having a focus on the z axis and having the z axis as a rotational symmetry axis.

Further, the lens portion of the lower region 11 is parallel to the z-axis and is located on the lower side thereof (that is, the boundary line 12 between the quadric surface region 9 and the lower region 11 and y−). When the point of intersection with the z-plane is point C, the focal point is on a straight line passing through point C and extending perpendicularly to the plane of the paper of FIG. 1, and this aspherical lens has this rotational axis as the axis of rotational symmetry.

It should be noted that the regions 10 and 11 can generally have a non-rotationally symmetric curved surface shape.

FIG. 2 shows an optical path diagram when the front portion of the projector type headlamp 1 is cut by the yz plane.

As shown by the light ray 13, the focal point Fu (the rear focal length is “Bfu”) for the upper area 10 of the xz plane is set on the optical axis of the front edge of the upper edge of the light shielding plate 5. There is.

The focus Fd (the rear focal length is “Bfd”) of the lower area 11 of the xz plane is set below the focus Fu.

That is, the focus Fd is near the intersection of the straight line 14 of y = −ΔD (where ΔD> 0) and the light shielding plate 5, and Bfd is made equal to Bfu, but generally Bfd ≧ Bfu To be done.

FIG. 4A is a graph for explaining the action of reducing chromatic aberration in the present embodiment, and shows the height of the lens when the projection lens is cut along the yz plane, that is, the y coordinate. As an example, the relationship between the angle formed by the direction of the corresponding outgoing light ray and the optical axis (this is defined as “θv”, upward light is defined as θv> 0, and downward light is defined as θv <0). It is shown.

In this example, Bfu = Bfd = 30 (mm), and shows a characteristic curve when a blue light source (486 nm) is placed at the focal point Fu and ray tracing is performed, and ΔD is 0, 1, The graph curves when changed to 2 and 3 (mm) are V (0), V (1), V (2), and V (3), respectively.

The optical path diagram of FIG. 4B shows the definitions of various constants. Point P is the principal point and f is the focal length.

As is clear from the graph curve, if ΔD ≧ 2 (mm), then θv <0 in the lower part of the lens, that is, the outgoing light beam is controlled downward, so that the blue light is below the cut line. Therefore, the chromatic aberration becomes inconspicuous.

That is, by shifting the optical axis of the lower side portion of the lens below the optical axis of the upper side portion, the light passing through the lower side portion of the lens can be made downward light.

In order to obtain the approximate value of the angle θv, the equation “ΔD = f · Tanθv” may be used.

FIG. 5 shows a light distribution pattern 15 obtained by the projector type headlight 1, and a pattern 16 shown by a chain double-dashed line in the figure is obtained by the lens portion of the quadric surface area 9. A pattern 17 indicated by a solid line equal candela line is a pattern obtained by the lens portion of the region 10 (the upper edge thereof is cut by a solid cut line 17 C), and a broken line equal candela line. The pattern 18 shown is a pattern obtained by the lens portion of the region 11 (the upper edge thereof is cut by the broken cut line 18C).

In the figure, “H-H” indicates a horizontal line, and “V-V” indicates a vertical line.

As shown in the figure, the pattern 17 formed by the upper area 10 is located immediately below the horizontal line H-H, the pattern 16 formed by the quadric surface area 9 is located under the horizontal line H-H, and the pattern 18 formed by the lower area 11 is formed. It is the lowest of the three.

Two cut lines are formed due to the existence of the regions 10 and 11, but since the pattern 18 of the lower region 11 overlaps with the patterns 17 and 16 of the upper region 10 and the quadric surface region 9, The cut line 18C of becomes inconspicuous.

Next, a projector type headlamp 1A according to a second embodiment of the present invention will be described with reference to FIGS. 6 to 9.

The projection lens 8A shown in the second embodiment differs from the projection lens 8 shown in the first embodiment in that the projection lens 8A according to the second embodiment has regions 10 and 11 in the regions. This is a point that has been further subdivided. Therefore, the difference between the two will be mainly described below, and those parts that are functionally different from those of the first embodiment will be assigned the same reference numerals as those used in the first embodiment. Therefore, the description will be omitted.

FIG. 6 is a front view of the projection lens 8A, and an axis extending in the horizontal direction orthogonal to the z-axis (the direction toward the light source is the positive direction) coinciding with the optical axis L-L is the x-axis. (The right side is the square direction.), The axis extending in the vertical direction orthogonal to the x axis is the y axis (the upward direction is the square direction), and the origin of these orthogonal coordinate axes is the projection lens 8A. The coordinate system is set to match the vertex O.

At the center of the projection lens 8 A, a rectangular quadratic curved surface area 9 that extends horizontally along the x-axis is located, and areas 19 and 20 are located above and below the quadric surface area 9. positioned.

The left side region 19 located on the left side of the yz plane is a sectoral region having a predetermined center angle with the point O as the center, and has a spherical lens shape.

The right side region 20 located on the right side of the y-z plane is a fan-shaped region having a predetermined center angle with the intersection C of the lower boundary of the quadric surface region 9 and the y-z plane as the center. It is defined as a region and has an aspherical lens shape whose axis of rotation symmetry is an axis parallel to the z axis and passing through the point C.

The regions 21 and 22 are located along the y-axis, and the region 21 is located above the xz plane and is a fan-shaped region having a predetermined center angle with the point O as the center. It is located on the lower side of the −z plane, and is a fan-shaped region having a predetermined center angle with the point C as the center.

A region 23 located between the left region 19 and the upper region 21, a region 24 located between the left region 19 and the lower region 22, and a region located between the right region 20 and the upper region 21. 25, the region 26 located between the right region 20 and the lower region 22 is a transition region, and these regions are rearward at each position so that the rear focal length is continuous at the boundary with the adjacent region. It is designed so that the focal length changes gradually.

FIG. 7 is an optical path diagram when the front portion of the projector-type headlight 1A is cut by the yz plane.

As shown by the light ray 27, the lens portion of the upper region 21 has a fixed focal point Fu having a rear focal length Bfu, and the focal point Fu is located on the optical axis of the upper edge front end of the light shielding plate 5.

Further, as shown by the ray 28, the lens portion of the lower region 22 has a focal point Fd having a backward focal length Bf d (> Bfu), and the focal point Fd passes through the point C and is parallel to the z axis. It is set above 14.

FIG. 8 is an optical path diagram when the front portion of the projector type headlamp 1A is cut by the xz plane.

As shown by the ray 29, the lens portion of the left side region 19 has a spherical shape with a radius R on the exit surface side, has a rear focal length of Bfs, and has a focal point Fs positioned behind the focal point Fu.

Further, as shown by the light ray 30, the lens portion of the right side region 20 has a focal point Ft located at the rear focal length Bft (<Bfs) and behind the focal point Fu.

Therefore, the quadric surface region 9 is not symmetrical with respect to the yz plane, and has a shape in which a sphere having a radius R and a quadric surface with a rear focal length Bft are connected in the yz plane.

FIG. 9 shows a light distribution pattern obtained by the projector-type headlight 1A and a light distribution obtained by a conventional projector-type headlight using an aspherical lens having a rotational symmetry about the optical axis as a projection lens. The difference between the two is schematically shown in comparison with a pattern. A pattern 31 shown by a solid line isocandela line shows a light distribution pattern according to the present embodiment, and a pattern 32 shown by a dashed line candela line. Shows the conventional light distribution pattern. In the figure, "H-H" indicates a horizontal line and "V-V" indicates a vertical line. Then, "CL" located immediately below the horizontal line H-H indicates a cut line.

As shown in the figure, the pattern 31 of this embodiment has a larger diffusion angle in the horizontal direction, but this is mainly due to the action of the regions 19 and 20.

Regarding the portion above the cut line CL, there is contribution of light from the transition regions 23 and 25 and regions 19 and 20 on the upper side of the xz plane, and the light contributes above the horizontal line H-H. It becomes easier to visually recognize the signs and the like that are located, and the peripheral portion of the cut line becomes slightly blurred, so that color unevenness becomes less noticeable.

However, in the second embodiment, as in the first embodiment, the blue light can be directed to the lower side of the cut line in the lower portion, so that the chromatic aberration is not noticeable and the lens is of course not conspicuous. The diffusion angle in the horizontal direction can be increased only by the action of.

In this embodiment and the first embodiment, the projection lens having a convex flat shape is shown. However, as in the projection lens 8B shown in FIG. Needless to say, they may be designed in a different manner or may have a meniscus shape.

[0061]

[Effect of device]

 As is clear from the above description, according to the present invention, the focal point of the lower part of the lens is shifted downward from the focal point of the upper part of the lens, and the rear focal length of the lower part of the lens is adjusted. By designing the rear focal length of the upper part to be greater than or equal to the rear focal length, the light passing through the lower part of the lens is directed downward, and the blue light is directed below the cut line to reduce the effects of chromatic aberration. .

Further, when the rear focal length of the regions adjacent to the upper and lower sides of the quadric surface region is made larger than the rear focal length of the upper part of the lens, the light distribution pattern diffused in the horizontal direction is generated only by the lens action. As a result, it is not necessary to complicate the structure of the reflector to create the horizontal diffusion effect.

[Brief description of drawings]

FIG. 1 is a front view of a projection lens according to a first embodiment of the present invention.

FIG. 2 is an optical path diagram in a vertical cross section of the projection lens according to the first example.

FIG. 3 is a perspective view schematically showing a configuration example of a projector type headlight.

FIG. 4A is a graph diagram for explaining chromatic aberration in a vertical section in the projection lens according to Example 1, and FIG. 4B is an optical path diagram showing definitions of various constants and the like.

FIG. 5 is a diagram schematically showing a light distribution pattern according to the first embodiment.

FIG. 6 is a front view of a projection lens according to a second embodiment of the present invention.

FIG. 7 is an optical path diagram in a vertical cross section of a projection lens according to a second example.

FIG. 8 is an optical path diagram in a horizontal cross section of a projection lens according to a second example.

FIG. 9 is a diagram showing a light distribution pattern according to a second embodiment in comparison with a conventional light distribution pattern.

FIG. 10 is a schematic view showing a modified example of the projection lens.

FIG. 11 is a schematic cross-sectional view of a lamp showing a problem in a conventional projector-type headlight.

FIG. 12 is a front view showing a projection lens of a conventional projector-type headlight.

[Explanation of symbols]

 1 Projector Headlight 2 Reflector F1 First Focus Position F2 Second Focus Position 5 Light Block 8 Projection Lens 9 First Area 10 Second Area Fu Focus 11 Third Area Fd Focus Bfu, Bfd Rear Focal length LL Optical axis 1A Projector type headlamp 8A Projection lens 19, 20 (Adjacent to the first area) Area 21 Second area 22 Third area Bfs, Bft Rear focal length 8B Projection lens

Claims (2)

[Scope of utility model registration request] 1. A light source is arranged at a first focus position of a reflecting mirror, and reflected light is condensed at a second focus position of the reflecting mirror,
In the projector-type headlamp configured to project the pattern image through the front projection lens after limiting the cut line by the light-shielding plate arranged so that the upper edge is located in the vicinity of the focal position of (1) The shape of the emission surface of the first region, which is positioned so as to extend in the horizontal direction approximately in the center of the projection lens, has a quadric surface shape. (2) The first region located above the first region The focal point of the second region is located near the upper edge of the light shielding plate, and (3) the rear focal length of the third region located below the first region is rearward of the second region. A projector-type headlight, wherein the focal length is equal to or longer than the focal length, and (4) the focal point of the third region is located below the focal point of the second region. 2. The projector type headlight according to claim 1, wherein the second region and the third region are fan-shaped regions arranged along the vertical direction when viewed from the front, and the first region. Projector-type headlights, the focal points of which are adjacent to the upper and lower sides of the lamp are located on the optical axis of the lamp, and the rear focal length thereof is larger than the rear focal distance of the second region. light.