JPH06201522A - Optical axis aligning method for headlight - Google Patents

Abstract

PURPOSE:To enable accurately aligning the optical axis of a headlight on the basis of the actual position of a light source as a reference even when the position of the light source of the headlight is shifted. CONSTITUTION:A grating body provided with a plurality of longitudinally-long grating holes arranged in the shape of a matrix is disposed in front of a headlight and the irradiation area and illuminance of a light transmitted through each grating hole in each irradiation region corresponding to each grating hole are measured. The irradiation areas of the irradiation regions (X1, Y2) and (X5, Y2) corresponding to the grating holes being opposed right to virtual light sources on the opposite right and left sides on a reflector of the headlight and of the irradiation regions between them are large and the center (X3, Y2) of distribution of the regions of which the area is large is the position of a real light source. When the direction of an optical axis is regular, an illuminance distribution being symmetric longitudinally and laterally with respect to the regions being present in a prescribed positional relationship with the position of the light source as shown in Fig. (a) (coinciding with the position of the light source in the Figure) as the center, is obtained. By adjusting the direction of the headlight so that this illuminance distribution be obtained, accurate adjustment of the optical axis can be executed.

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 a headlight for an automobile or other vehicle.

[0002]

2. Description of the Related Art Conventionally, as a method of this kind, Japanese Patent Publication No.
According to Japanese Patent No. 9298, a CCD camera captures an image of a light distribution pattern irradiated on a screen arranged in front of a headlight, and the barycentric coordinate of illuminance is measured by image processing. The barycentric coordinate is used as a position of an optical axis on the screen. It is known to adjust the optical axis of the headlight so that it 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 pass range on the screen where the optical axis should be located 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 deviated, the optical axis falls within the acceptable range and accurate optical axis adjustment cannot be performed.

Further, according to the Japanese Patent Application Laid-Open No. 4-147030 filed by the applicant of the present application, a grid body having a plurality of grid holes, which are long in the front-rear direction and arranged in a matrix, is arranged in front of the headlight. There has been proposed a method of adjusting the optical axis of a headlight by measuring the irradiation area and illuminance of transmitted light of each grating hole in each irradiation area divided into a matrix by the grating hole. 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.

[0005]

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. For example, in the spot beam type headlight, as shown in FIG. 6A, light rays are emitted from virtual light sources a1 and a2 on the reflecting mirrors on one side and the other side of the filament a, and in the flat beam type headlight,
As shown in FIG. 6B, it is considered that the light rays are emitted from the virtual light source in the form of a plane on the reflecting mirror.

When the optical axis of such a headlight is adjusted on the basis of the irradiation pattern transmitted through the grating, the aperture size of each grating hole is adjusted so that the virtual light sources on both sides are within the visual field of any one grating hole. If the size is set to fit, the irradiation area that maximizes the irradiation area is specified as one, but if the opening size of the lattice hole is reduced to reduce the adjustment tolerance of the optical axis, the irradiation area becomes the maximum. Therefore, it becomes impossible to simply determine the position of the light source, and a plurality of irradiation areas with high illuminance also occur, so that the position of the optical axis cannot be easily specified.

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 and enables the optical axis of a headlight to be adjusted accurately.

[0008]

[Means for Solving the Problems] In order to achieve the above object,
According to the present invention, in front of the headlight, a grid body having a plurality of grid holes elongated in the front-back direction is arranged in a matrix, and transmitted light of each grid hole in each irradiation area divided into a matrix by each grid hole. The irradiation area and the illuminance are measured, the position of the light source of the headlight is indexed based on the distribution of the irradiation area having a large irradiation area, and the irradiation area existing in a predetermined positional relationship with respect to the position of the light source is used as a reference. The optical axis of the headlight is adjusted so that the illuminance distributions of the left and right irradiation areas and the illuminance distributions of the upper and lower irradiation areas have respective predetermined distributions. 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.

[0009]

The irradiation area is maximized in a plurality of irradiation areas corresponding to a plurality of lattice holes facing the virtual light source on the reflecting mirror, but the light source (filament) of the headlight is based on the large irradiation area distribution. The position of can be accurately determined. Then, if the headlight is in a normal orientation, the upper and lower illuminance distributions centering on the irradiation area existing in a predetermined positional relationship with the light source and the left and right illuminance distributions have predetermined distributions, respectively, and these illuminance distributions have the predetermined distributions. If the optical axis is adjusted so as to have a distribution, the optical axis of the headlight is accurately adjusted to the normal direction.

[0010]

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 rays transmitted through the grating body 3 on the screen 4 is a pattern in which the transmitted light of each lattice hole 2 is irradiated to each irradiation area divided into a matrix corresponding to each lattice 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 a spot beam type as shown in FIG. 6A, the irradiation pattern for the screen 4 is shown by a histogram showing a three-dimensional illuminance distribution as shown in FIG. Become. 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 the coordinate values of the n-th irradiation area on the right side and the m-th irradiation area on the upper side from the irradiation area in the lower left corner are represented by (Xn, Ym) The coordinate value of the irradiation area corresponding to the grid hole 2 whose hole axis passes through the virtual light source a1 on the left side of the headlight B is (X1, Y2), and the hole axis is in the grid hole 2 passing through the virtual light source a2 on the right side of the headlight B. The coordinate value of the corresponding irradiation area is (X5, Y2), and (X1, Y
2), (X2, Y2), (X3, Y2), (X4, Y
2), the five irradiation areas of (X5, Y2) are respectively irradiated with light rays over the entire surface thereof, and the distribution centers (Xc, Yc) of the irradiation areas having a large irradiation area, that is, (X3, Y2) are actual. The light source filament a is located on the screen 4.

If the headlight B is oriented normally, as shown in FIG. 4 (a), an irradiation area having a predetermined positional relationship with the actual light source (in the present embodiment, coincides with the actual light source (X3, The illuminance distribution shows that the illuminance gradually decreases with increasing distance in the vertical and horizontal directions from the irradiation area (Y2)), but if the optical axis shifts, the symmetry of the illuminance distribution around the irradiation area collapses. When the optical axis shifts to the lower right, for example, it becomes as shown in FIG.

The irradiation pattern of the flat beam type headlight as shown in FIG. 6B is as shown in FIG. 5, and the X-coordinates X2 to X5 and the Y-coordinates Y1 to Y3 face the planar virtual light source. The irradiation area is maximized in the irradiation area. Also,
If the orientation of the headlight is normal, as shown in FIG. 5 (a), the illuminance in the irradiation area is almost the same, but
If the optical axis shifts, the even distribution of illuminance in these irradiation areas collapses, and if the optical axis shifts to the lower right, for example, it will be as shown in FIG. 5 (b). Although the distribution center (Xc, Yc) of the irradiation area having a large irradiation area is located in the gap between the irradiation areas as shown in the figure, in this case, irradiation on one side adjacent to (Xc, Yc), for example, irradiation on the left side. A measurement process, which will be described later, is performed by setting the area as (Xc, Yc).

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 are calculated (S
4), Lh is binarized to calculate the distribution center coordinates (Xp, Yp) of the irradiation area having an illuminance of Lh or more (S5).

Here, unless the reflecting mirror or 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, the deviation amount between Yp and Yc is calculated (S8), this deviation amount is converted into an adjustment amount in the vertical direction, and vertical adjustment is performed (S9, S10), and then X = Xc. Is scanned up and down to calculate the illuminance difference between the total illuminance of the irradiation area group above Yc and the total illuminance of the irradiation area group below Yc (S11), and it is determined whether or not this illuminance difference has become a reference value. (S12), vertical adjustment is repeated until the illuminance difference decreases to the reference value, and when the illuminance difference decreases to the reference value, the left and right adjustments are performed to align the headlight in the left-right direction.

In the left-right adjustment, Y = Yc is left-right scanned to calculate the illuminance difference between the total illuminance of the left irradiation area group and the total illuminance of the right irradiation area group of Xc (S13). The difference is converted into the amount of adjustment in the left-right direction and the left-right adjustment is performed (S
14, S15), it is determined whether or not the illuminance difference has reached the reference value (S16), and left and right adjustments are repeated until the illuminance difference decreases to the reference value. When the illuminance difference decreases to the reference value, the optical axis adjustment is performed. Complete.

It should be noted that the conversion coefficient of the adjustment amount conversion in steps S9 and S14 and the reference value in steps S12 and S16 must be set to different values for the spot beam type and the flat beam type. Here, the number of irradiation areas that maximize the irradiation area is greater in the flat beam type, and based on this number, the model determination of the spot beam type or the flat beam type is performed, and the above conversion coefficient and reference value are set. To do.

Further, in the above embodiment, the illuminance distribution of the upper and lower irradiation area groups and the illuminance distribution of the left and right irradiation area groups of the irradiation area of (Xc, Yc) are measured as a difference of the total value of the maximum illuminance of each irradiation area. However, a predetermined ratio of Lh, for example, an illuminance L of 70%
It may be binarized by m, and may be measured as a difference in the total value of the irradiation areas of Lm or more in each irradiation area, or may be measured as the difference in the total value of the volumes of the histograms shown in FIGS. 4 and 5. good.

[0021]

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 headlight of the headlight can be detected with reference to the actual position of the light source. The optical axis can be adjusted accurately.

[Brief description of 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.

4A and 4B are histograms showing irradiation patterns of a spot beam type headlight.

5A and 5B are histograms showing irradiation patterns of a flat beam headlight.

6 (a) and 6 (b) are diagrams showing a light beam irradiation direction and a light distribution pattern of a spot beam type and a flat beam type headlight, respectively.

[Explanation of symbols]

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

Claims (1)

[Claims] 1. A grid body having a plurality of grid holes elongated in the front-rear direction arranged in a matrix is arranged in front of the headlight, and each grid hole is transmitted through each irradiation area divided into a matrix by each grid hole. The irradiation area and illuminance of the light are measured, the position of the light source of the headlight is indexed based on the distribution of the irradiation area having a large irradiation area, and the irradiation area existing in a predetermined positional relationship with respect to the position of this light source is used as a reference. An optical axis adjusting method for a headlight, wherein the optical axis of the headlight is adjusted so that the illuminance distributions of the left and right irradiation areas and the illuminance distributions of the upper and lower irradiation areas have respective predetermined distributions.