JP3041557B2 - 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 the optical axis of headlights for automobiles and other vehicles.

[0002]

2. Description of the Related Art Conventionally, this type of method has been disclosed in
According to Japanese Patent No. 9298, a light distribution pattern applied to a screen disposed in front of a headlight is imaged by a CCD camera, and the barycentric coordinates of illuminance are measured by image processing. Is known in which the optical axis of the headlight is adjusted so as to be located within a predetermined range.

Conventionally, it is assumed that the light source (filament) of the headlight is located at a predetermined set position, and an acceptable range on the screen where the optical axis should be located based on the set position and the distance to the screen. Although the actual position of the light source may deviate from the set position due to suspension initial adaptation, tire air pressure, assembly error, etc., in this case, the direction of the optical axis is Even if it is deviated, the optical axis falls within the acceptable range, and accurate optical axis adjustment cannot be performed.

[0004] Conventionally, according to Japanese Patent Application Laid-Open No. 4-147030 filed by the applicant of the present invention, a grid body having a plurality of grid holes elongated in the front-rear direction is arranged in front of a headlight. There has been proposed a method of adjusting the optical axis of the headlight by measuring the irradiation area and illuminance of the transmitted light of each grid hole in each irradiation area divided in a matrix by the grid holes. According to this method, the irradiation area corresponding to the lattice hole whose extension line of the hole axis of the lattice hole passes through the light source of the headlight is irradiated with light over the entire surface thereof, and the irradiation area is maximized. The illumination area corresponding to the lattice hole corresponding to the optical axis of the headlight has the highest illuminance. Therefore, even if the position of the light source deviates from the set position due to the initial adaptation of the suspension or the variation of the air pressure of the tire, the position of the light source can be determined from the irradiation area where the irradiation area is maximum, and this light source position and The optical axis can be adjusted based on the position of the optical axis determined from the irradiation area where the illuminance is maximized so that the optical axis is in the normal direction.

[0005]

By the way, when dealing with a light distribution pattern of a headlight, it is more appropriate to consider that light rays are emitted from a plurality of virtual light sources on a reflecting mirror instead of one point light source. For example, in a spot beam type headlight, as shown in FIG. 6 (a), light rays are emitted from virtual light sources a1 and a2 on a reflecting mirror on one side of a filament a and the other side, and in a flat beam type headlight,
As shown in FIG. 6B, it is considered that light is emitted from a planar virtual light source on the reflecting mirror.

When the optical axis of such a headlight is adjusted based on the irradiation pattern transmitted through the lattice body, the virtual light sources on both sides are set within the field of view of any one of the lattice holes. If it is set to a size that can fit, the irradiation area with the largest irradiation area is specified as one.However, if the opening size of the lattice hole is reduced to reduce the adjustment tolerance of the optical axis, the irradiation area will be the maximum. A plurality of irradiation areas are generated, and the position of the light source cannot be simply determined. Further, a plurality of irradiation areas having high illuminance also occur, and the position of the optical axis cannot be easily specified.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an optical axis adjusting method capable of accurately adjusting the optical axis of a headlight by solving the above-mentioned problems when using a lattice.

[0008]

In order to achieve the above object,
The present invention arranges a grid body having a plurality of grid holes elongated in the front-rear direction in a matrix in front of a headlight, and transmits light transmitted through each grid hole in each irradiation area divided into a matrix by each grid hole. The illumination area and illuminance of the headlight are measured, and the position of the light source of the headlight is determined based on the distribution of the illumination area having a large illumination area, and the position corresponding to this light source position
Or the difference between the total illuminance in the left and right irradiation area groups and the upper and lower irradiation area groups
The optical axis of the headlight is adjusted so that the difference between the total illuminance and the difference becomes a predetermined reference value . The lattice body may be one in which a plurality of vertical and horizontal plates are framed in a lattice shape or one in which a plurality of cylindrical bodies are assembled.

[0009]

The illumination area is maximized in a plurality of illumination areas corresponding to a plurality of lattice holes facing the virtual light source on the reflector, but the light source (filament) of the headlight is based on the distribution of the illumination area having a large illumination area. Can be accurately determined. Then, if the orientation of the headlight is normal, it becomes each predetermined distribution illuminance distribution in the vertical centered on the irradiation area corresponding to the position of the light source and the left and right illuminance distribution, the irradiation
The sum of the irradiation area groups on the left and right of the irradiation area
The difference between the illuminance and the total
If the optical axis is adjusted so as to be a reference value corresponding to the above-mentioned predetermined illuminance distribution, the optical axis of the headlight is accurately adjusted in a 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, and the device 1 is, as shown in FIG. ,
A grid body 3 having a plurality of grid 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 grid body 3 (on the side opposite to the headlight B), and a pair in front of the screen 4 And a pair of tools 7, 7 for inputting an image signal from the camera 5 to a computer 6 having a built-in image processing circuit and adjusting the vertical and horizontal directions of the headlight B. Is controlled by the computer 6 to adjust the optical axis of the headlight B.

The irradiation pattern of the light beam transmitted through the grid 3 onto the screen 4 is a pattern in which the light transmitted through each grid hole 2 is applied to each of the irradiation areas divided in a matrix corresponding to each grid hole 2. . Then, the irradiation area corresponding to the grid hole passing through the light source of the headlight B is irradiated with light rays over the entire surface thereof, and the irradiation area becomes large. The illumination area corresponding to the lattice hole 2 corresponding to the optical axis has a high illuminance.

Here, when the headlight B is of a spot beam type as shown in FIG. 6A, an irradiation pattern on the screen 4 is represented by a histogram showing a three-dimensional illumination distribution as shown in FIG. Become. In the figure, the X axis and the Y axis are coordinate axes in the left-right direction and the up-down direction, respectively. From the irradiation area at the lower left corner, the coordinate values of the n-th irradiation area to the right and the m-th irradiation area upward are represented by (Xn, Ym). The coordinate value of the irradiation area whose hole axis corresponds to the grid hole 2 passing through the virtual light source a1 on the left side of the headlight B is (X1, Y2). The coordinate values of the corresponding irradiation area are (X5, Y2) and (X1, Y
2), (X2, Y2), (X3, Y2), (X4, Y
2) and (X5, Y2) are irradiated with light rays over their entire surfaces, respectively, and the distribution center (Xc, Yc) of the irradiation area having a large irradiation area, that is, (X3, Y2) is actually obtained. The filament a, which is the light source, is located on the screen 4.

If the direction of the headlight B is normal, as shown in FIG. 4A, an irradiation area having a predetermined positional relationship with respect to the real light source (in this embodiment, it matches the real light source (X3, Y2) shows an illuminance distribution such that the illuminance gradually decreases as the distance from the center increases or decreases from left to right or left or right, but if the optical axis shifts, the symmetry of the illuminance distribution centering on the illuminated area is lost. When the optical axis shifts, for example, to the lower right, 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 coordinate is X2 to X5 and the Y coordinate is Y1 to Y3 directly facing the planar virtual light source. The irradiation area is maximized in the irradiation area. Also,
If the headlight direction is normal, as shown in FIG. 5A, the illuminance of the above-mentioned irradiation area becomes almost the same,
If the optical axis shifts, the uniformity of the illuminance in these irradiation areas deteriorates, and if the optical axis shifts, for example, to the lower right, it becomes as shown in FIG. In the drawing, the distribution center (Xc, Yc) of the irradiation area having a large irradiation area is located in the gap between the irradiation areas. In this case, one side adjacent to (Xc, Yc), for example, the irradiation on the left side A measurement process described below is performed with the area set as (Xc, Yc).

FIG. 3 is a flowchart for adjusting the optical axis of the headlight B.
First, the irradiation pattern of the screen 4 is captured 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 the illuminance are set (S3). , Ll to obtain an irradiation area of Ll or more in each irradiation area, calculate the distribution center coordinates (Xc, Yc) of the irradiation area having the maximum irradiation area, and calculate (Sc).
4) Binarization is performed using Lh, and distribution center coordinates (Xp, Yp) of the irradiation area having the illuminance equal to or greater than Lh are calculated (S5).

Here, as long as there is no distortion or the like in the reflecting mirror or lens of the headlight B, the illuminated areas having the illuminance of Lh or more should be concentrated in a specific area, and the illuminated areas of high illuminance are scattered apart from each other. If yes, an error is displayed and the process is stopped (S6, S7).

When the irradiation areas of high illuminance are not scattered, firstly, the vertical adjustment of the headlight B in the vertical direction is performed. At the time of this adjustment, the amount of deviation between Yp and Yc is calculated first (S8), and this amount of deviation is converted into an amount of adjustment in the up-down direction to perform up-down adjustment (S9, S10), and then X = Xc 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 determine whether or not this illuminance difference has reached the reference value. (S12) The vertical adjustment is repeated until the illuminance difference decreases to the reference value. When the illuminance difference decreases to the reference value, the left and right adjustment for aligning the headlight in the left-right direction is performed.

At the time of right and left adjustment, Y = Yc is scanned right and left to calculate an 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 an adjustment amount in the left-right direction, and left-right adjustment is performed (S
14, S15), it is determined whether or not the illuminance difference has reached the reference value (S16), and the 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 coefficients for the adjustment amount conversion in steps S9 and S14 and the reference values in steps S12 and S16 need to be set to different values for the spot beam type and the flat beam type. Here, the number of irradiation areas with the maximum irradiation area is larger in the flat beam type, and based on this number, the type of the spot beam type or the flat beam type is determined, and the above conversion coefficients and reference values are set. I do.

Further, in the above embodiment (Xc, Yc) maximum illumination intensity sum of the differences and the respective irradiation areas of the total illumination in the difference between the left and right irradiation region group total illuminance at the upper and lower irradiation area groups of the irradiation area of the Is binarized at a predetermined ratio of Lh, for example, illuminance Lm of 70%, and L of each irradiation area is binarized.
m may be measured as a difference between the total values of the irradiation areas of m or more,
Further, it may be measured as a difference between the total values of the volumes of the histograms shown in FIGS.

[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 displaced, the position of the headlight is determined with reference to the actual position of the light source. The optical axis can be adjusted accurately.

[Brief description of the drawings]

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

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

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

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

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

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

[Explanation of symbols]

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

Claims (1)

(57) [Claims] 1. A grid having a plurality of longitudinal grid holes arranged in a matrix in the front-rear direction is arranged in front of a headlight, and the transmission of each grid hole in each irradiation area divided into a matrix by each grid hole is provided. Measures the light irradiation area and illuminance, determines the position of the headlight light source based on the distribution of the irradiation area with a large irradiation area, and responds to this light source position
Or the difference between the total illuminance in the left and right irradiation areas and the upper and lower irradiation areas based on the adjacent irradiation areas .
The optical axis of the headlight is adjusted so that the difference between the total illuminance and the total illuminance becomes a predetermined reference value .