JP2681584B2 - Headlight optical axis adjustment method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for adjusting an optical axis of an asymmetric light distribution type headlight generally called an ECE method.

[0002]

2. Description of the Related Art An asymmetric light distribution type headlight is shown in FIG.
As shown in (a), a shading plate b is provided below the low-beam filament a arranged in front of the focal point of the reflecting mirror, and is reflected by the lower half of the reflecting mirror to irradiate upward.
By cutting down the downward light from the filament a, a clear light-dark boundary line, that is, a cutoff line CL appears in the light distribution pattern, and one side portion of the light shielding plate b in the horizontal direction is cut out so that a vertical line in the figure is formed. The downward light from the marked area is reflected by the reflecting mirror and is irradiated to the hatched area on the other side in the horizontal direction, and the cut-off line CL rises obliquely upward on the other side in the horizontal direction. . Incidentally, the one shown in the figure is for traffic on the left side, and the cut-off line CL is raised on the left side by notching the right side portion of the light shielding plate b. In the figure, a'denotes a filament for high beam which is arranged at the focal position of the reflecting mirror.

Conventionally, as a method of adjusting the optical axis of such an asymmetrical light distribution type headlight, according to Japanese Patent Application Laid-Open No. 61-17934, a light distribution pattern irradiated on a screen arranged in front of the headlight is measured by a CCD camera. It is known that an image is taken, an isoilluminance curve is created by image processing to obtain a cutoff line, and the optical axis of the headlight is adjusted so that the cutoff line is located within a predetermined range.

By the way, conventionally, it is assumed that the light source (filament) of the headlight is located at a predetermined setting position, and the cut-off line should be located on the screen based on the setting position and the distance to the screen. However, the actual position of the light source may deviate from the set position due to initial running-in of the suspension, tire air pressure, assembly error, etc.In this case, the direction of the optical axis is the normal direction. Even if it is out of alignment, the cut-off line falls within the acceptable range, and accurate optical axis adjustment cannot be performed.

Further, conventionally, according to Japanese Patent Application Laid-Open No. 4-147030 filed by the applicant of the present application, which mainly relates to the adjustment of the optical axis in a high beam, a matrix of longitudinal grid holes in the front-rear direction is provided in front of the headlight. A method for adjusting the optical axis of the headlight by arranging a plurality of grids arranged in a matrix and measuring the irradiation area and illuminance of the transmitted light of each grating hole in each irradiation area divided by each grating hole in a matrix Is proposed. According to this method, the extended area of the hole axis of the grid hole corresponds to the grid hole that passes through the light source of the headlight, the irradiation area is maximized by irradiating light rays over the entire surface, while, The illuminance is maximum in the irradiation area corresponding to the grid hole that matches the optical axis of the headlight. Therefore, even if the position of the light source deviates from the set position due to the initial familiarity of the suspension, the tire air pressure variation, etc., the position of the light source can be determined from the irradiation region where the irradiation region is the maximum. The optical axis can be adjusted so that the optical axis has a regular orientation based on the position of the optical axis indexed from the irradiation area where the illuminance is maximum.

[0006]

By the way, when dealing with the light distribution pattern of the headlight, it is more appropriate to consider that the light rays are emitted from a plurality of virtual light sources on the reflecting mirror instead of one point light source. When irradiating a low beam of asymmetric light distribution, as shown in FIG. 6B, the light beam from the virtual light source a1 on one side of the reflecting mirror irradiates the lower region of the horizontal portion of the cutoff line CL, and the reflecting mirror It is considered that the light beam from the other virtual light source a2 on the other side is applied to the lower region of the rising portion of the cutoff line CL.

When the optical axis of such an asymmetrical light distribution type headlight is adjusted based on the irradiation pattern transmitted through the grating body, the opening size of each grating hole is adjusted so that both sides are within the field of view of any one grating hole. If the size is set to fit the virtual light source of, the irradiation area that maximizes the irradiation area is specified as one. However, if the aperture size of the lattice hole is reduced to reduce the adjustment tolerance of the optical axis, Since there are multiple irradiation areas with the maximum area, it is not possible to simply determine the position of the light source.Furthermore, a light beam that is tilted to some extent with respect to the hole axis of the lattice hole cannot pass through the lattice hole. If the irradiation areas corresponding to the grid holes that are distant vertically and horizontally from the facing grid holes to some extent are not irradiated with light rays and cut-off lines enter these irradiation areas, the position of the cut-off line cannot be detected. It made.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an optical axis adjusting method which solves the above-mentioned problems in the case of using a grating body and is capable of accurately adjusting the optical axis of an asymmetrical light distribution type headlight. I am trying.

[0009]

In order to achieve the above object,
The present invention is a method for adjusting an optical axis of an asymmetrical light distribution type headlight, in which a grid body having a plurality of longitudinal grid holes arranged in a matrix is arranged in front of the headlight. The irradiation area and the illuminance of the transmitted light of each lattice hole in each irradiation area divided into a matrix are measured, and the position of the light source of the headlight is indexed based on the distribution of the irradiation area having a large irradiation area. Of the headlight so that the distribution pattern of the illuminance in the irradiation area existing in a predetermined positional relationship with respect to the position is a bifurcated pattern in which the illuminance on both sides of the irradiation area is about the same as that of the central part of the irradiation area. It is characterized by adjusting the axis. Note that the lattice body may be formed by arranging a plurality of vertical and horizontal plates in a lattice shape, or may be an aggregate of a plurality of cylindrical bodies.

[0010]

The irradiation area is maximized in a plurality of irradiation areas corresponding to a plurality of lattice holes facing the plurality of virtual light sources on the reflecting mirror, but the light source of the headlight ( The position of the filament) can be accurately determined. By the way, in the asymmetric light distribution type headlight, the optical axes c1 and c2 of the light beams emitted from the virtual light sources a1 and a2 located on both sides of the filament a are directed in different directions, and the equal angle 2 of the intersection angle formed by these optical axes is set. The light rays from the virtual light source a1 on one side and the light rays from the virtual light source a2 on the other side are equally incident on the lattice hole matching the bisector c0 along the two diagonal lines in the longitudinal section. Thus, the distribution pattern of the illuminance in the irradiation area corresponding to the lattice hole is a bifurcated pattern in which the illuminance on both sides of the irradiation area is substantially the same as that of the central area of the irradiation area. If the optical axis of the headlight is in the normal direction, the equiangular bisectors will coincide with the lattice holes that have a predetermined positional relationship with the light source of the headlight. Therefore, if the optical axis is adjusted so that the distribution pattern of the illuminance in the irradiation area corresponding to the lattice hole becomes the above-mentioned bifurcated pattern, the optical axis of the headlight is accurately adjusted in the normal direction.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, reference numeral 1 denotes a measuring device arranged at a short distance of about 3 m in front of a headlight B of an automobile A to be stopped at a fixed position. The device 1 is as shown in FIG. ,
A lattice body 3 having a plurality of lattice holes 2 elongated in the front-rear direction in a matrix, a screen 4 made of frosted glass or the like provided on the front surface of the lattice body 3 (on the side opposite to the headlight B), and in front of the screen 4. A pair of tools 7, 7 for adjusting the vertical direction and the horizontal direction of the headlight B by inputting the image signal from the camera 5 to the computer 6 having the built-in image processing circuit. The servo driver unit 8 having the above is controlled by the computer 6 so that the optical axis of the headlight B is adjusted.

The irradiation pattern of the light beam transmitted through the grating body 3 on the screen 4 is such that the transmitted light of each grating hole 2 is irradiated to each irradiation area divided into a matrix corresponding to each grating hole 2. . Then, a light beam is irradiated over the entire surface of the irradiation area where the extension line of the hole axis of the grating hole 2 corresponds to the grating hole passing through the light source of the headlight B, and the irradiation area becomes large. The illumination area corresponding to the lattice hole 2 that matches the optical axis has a high illuminance.

Here, when the headlight B is an asymmetric light distribution type having an upper left cutoff line CL as shown in FIG. 6, the irradiation pattern on the screen 4 is shown by a histogram showing a three-dimensional illuminance distribution. As shown in FIG. In the figure, the X-axis and the Y-axis are the coordinate axes in the left-right direction and the vertical direction, respectively, and are the n-th one to the right of the irradiation area in the lower left corner,
Assuming that the coordinate value of the m-th irradiation area upward is represented by (Xn, Ym), the hole axis is the virtual light source a on the left side of the headlight B.
The coordinate value of the irradiation area corresponding to the lattice hole 2 passing through 1 is (X
1, Y2), the virtual light source a with the hole axis on the right side of the headlight B
The coordinate value of the irradiation area corresponding to the lattice hole 2 passing through 2 is (X
5, Y2), and (X1, Y2), (X2, Y2),
5 of (X3, Y2), (X4, Y2), (X5, Y2)
The individual irradiation areas are respectively irradiated with light rays over their entire surfaces, and the distribution center of the irradiation areas having a large irradiation area, that is, (X3, Y2) is the position on the screen 4 of the filament a which is the actual light source.

Further, it coincides with the equiangular bisector c0 of the intersection angle formed by the optical axis c1 of the light beam emitted from the left virtual light source a1 and the optical axis c2 of the light beam emitted from the right virtual light source a2. The light beam from the left virtual light source a1 and the light beam from the right virtual light source a2 are equally incident on the lattice hole 2 along the two diagonal lines in the longitudinal section,
The distribution pattern of the illuminance in the irradiation area corresponding to the lattice holes 2 is a bifurcated pattern in which both side portions are substantially higher than the central portion of the irradiation area. Then, if the optical axis of the headlight B is in the normal direction, an irradiation area having a predetermined positional relationship with the actual light source (in the headlight B used in this embodiment, the actual light source is coincident with (X3, Y2)). The illuminance of the illuminated area) is high and the distribution pattern of the illuminance is 2
It becomes a crotch pattern.

FIG. 5 shows an irradiation pattern for the screen 4 when the optical axis of the headlight B is shifted to the lower right. Although the distribution of the irradiation area having a large irradiation area does not change,
The distribution pattern of the illuminance in the irradiation area of (X3, Y2) that matches the actual light source shows that the illuminance of the light beam from the right virtual light source a2 irradiated to the left side of the area decreases due to the shift of the optical axis to the right. Then, the pattern becomes bilaterally asymmetrical.

The light beam emitted from the virtual light source a2 on the right side includes a component having a direction vector on the upper left side for forming a rising portion on the upper left side of the cutoff line CL (FIG. 6 (a)). (Reflected light in the area marked with the vertical line), and as a result, light rays from the virtual light source on the right side in the upper left corner of the plurality of irradiation areas located above and to the left of the irradiation area of (X3, Y2) that match the real light source. However, if the optical axis shifts downward, the illuminance decreases.

The flow of adjusting the optical axis of the headlight B is shown in FIG.
First, the irradiation pattern of the screen 4 is imaged by the CCD camera 5 (S1), the iris amount of the camera 5 is adjusted (S2), and the upper and lower thresholds Lh and Ll of illuminance are set (S3). , Ll is binarized to obtain an irradiation area equal to or larger than Ll of each irradiation area, and the distribution center coordinates (Xc, Yc) of the irradiation area having the maximum irradiation area ((X
3, Y2)) is calculated (S4), and the distribution center coordinates (X
p, Yp) ((X3, Y2) in FIG. 4 and (X
4, Y1)) is calculated (S5).

Here, unless the reflecting mirror or the lens of the headlight B is distorted, the irradiation areas having an illuminance of Lh or more should be concentrated in a specific area, and the irradiation areas having a high illuminance are scattered apart from each other. If so, an error is displayed and the process is stopped (S6, S7).

When the irradiation areas of high illuminance are not scattered, first, the vertical adjustment is performed to match the vertical direction of the headlight B. In this adjustment, first, of the irradiation areas having the maximum irradiation area, the X coordinate value of the irradiation area that is most displaced to the side where the cutoff line CL rises is Xa (X1 in FIGS. 4 and 5), and X = Xa. Scan up and down with (S
8), a predetermined ratio of Lh, for example, an illuminance Lm of 70%, is binarized, and X = Xa and an irradiation area below Yc (FIG. 4, FIG.
((X1, Y1), (X1, Y0) irradiation area in FIG. 5)
The area difference between the total irradiation area of Lm or more and the irradiation area above Yc (the irradiation area of (X1, Y3) (X1, Y4) in FIGS. 4 and 5) is Lm or more is calculated (( In step S9, the area difference is converted into an adjustment amount in the vertical direction for vertical adjustment (S10, S11). When the area difference reaches a predetermined value, the vertical adjustment is completed (S12), and the headlight B is moved in the horizontal direction. Adjust the right and left to match the orientation of.

In this adjustment, first (Xc, Yc)
And (Xp, Yp) based on the deviation amount between (Xp, Yp), it is determined whether the deviation of the optical axis is large or small (S13). When the deviation is large, left and right scanning is performed with Y = Yc (S14), and Lm Binarize,
From the total irradiation area of Lm or more and the irradiation area of Y = Yc and the irradiation area to the left of Xc (the irradiation areas of (X0, Y2), (X1, Y2), (X2, Y2) in FIGS. 4 and 5) The irradiation area on the right side ((X4, Y2) in FIGS. 4 and 5, (X5, Y
2), the area difference between the (X6, Y2) irradiation area) and the total irradiation area of Lm or more is calculated (S15), and the area difference is converted into a vertical adjustment amount to perform left and right rough adjustment ( S1
6, S17), and then the forked level difference of the forked illuminance distribution pattern in the irradiation area of (Xc, Yc) is detected (S1).
8). When the deviation of the optical axis is small, the process directly proceeds from S13 to S18. Then, the two-forked level difference is converted into an adjustment amount in the left-right direction for left-right adjustment (S19, S20), and it is determined whether or not the two-forked level difference is equal to or less than a predetermined value (S2).
1) The processes from S18 to S20 are repeated until the value becomes equal to or less than the predetermined value.

When the two-forked level difference becomes less than a predetermined value, it should be located above and below the rising portion of the cut-off line CL. Two irradiation areas determined based on (Xc, Yc). (For example, (X3, Y3) in FIG.
The pass / fail test is performed by detecting the illuminance difference in the (X3, Y4) irradiation area (S22). If the headlight B is normal,
This illuminance difference is equal to or greater than a predetermined value, but when the rising angle of the rising portion of the cutoff line CL deviates from the normal angle due to an assembly error of the filament a or the light shielding plate b, the rising portion has the above two irradiations. The areas do not pass through, and the illuminance difference falls below a predetermined value. Therefore, when the illuminance difference is equal to or larger than the predetermined value, the adjustment is completed as a pass (S23, S24),
When the illuminance difference does not reach the predetermined value, it is judged as unacceptable and an abnormality is displayed.

In the above embodiment, the area difference is obtained by binarizing with Lm in the steps S9 and S15, but the volume difference of the histograms shown in FIGS. 4 and 5 is obtained, and vertical adjustment and horizontal adjustment are performed. You may do it.

[0023]

As is apparent from the above description, according to the present invention, the position of the light source of the headlight can be detected, and even if the position of the light source is deviated, the asymmetric light distribution is performed with reference to the actual position of the light source. The optical axis of the mold headlight can be adjusted accurately.

[Brief description of the drawings]

FIG. 1 is a schematic side view of an example of an apparatus used for carrying out the method of the present invention.

FIG. 2 is a perspective view of an example of a lattice.

FIG. 3 is a flowchart showing an optical axis adjustment procedure of an example of the method of the present invention.

FIG. 4 is a histogram showing an irradiation pattern when the optical axis is in a normal direction.

FIG. 5 is a histogram showing an irradiation pattern when the optical axis is displaced.

6A is a perspective view showing the structure of a headlight, FIG.
(B) is a figure which shows the irradiation direction of the light beam from a headlight, and a light distribution pattern.

[Explanation of symbols]

B Headlight a Filament (light source) 2 Lattice hole 3 Lattice body 4 Screen 5 Camera 6 Computer

Claims (1)

(57) [Claims] 1. A method for adjusting an optical axis of an asymmetrical light distribution type headlight, wherein a grid body having a plurality of longitudinal grid holes arranged in a matrix in the front-rear direction is arranged in front of the headlight, and each grid hole is arranged. The irradiation area and the illuminance of the transmitted light of each lattice hole in each irradiation area divided by the matrix are measured, and the position of the light source of the headlight is indexed based on the distribution of the irradiation area having a large irradiation area. The illuminance distribution pattern in the irradiation area existing in a predetermined positional relationship with the position of the light source is a bifurcated pattern in which the illuminance on both sides of the irradiation area is approximately the same as the central area of the irradiation area. A method of adjusting an optical axis of a headlight, which comprises adjusting an optical axis.