JPH0814523B2 - Headlamp main optical axis inspection method - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for inspecting a main optical axis of a vehicle headlamp.

(Prior Art) Conventionally, in the automobile assembly line, the main optical axes of the left and right headlamps are inspected in the final inspection process. For example, the light distribution of the headlamps illuminated on the test screen in front of the automobile. The pattern is photographed with a TV camera, the photographed light distribution pattern is image-processed to find the barycentric position of the iso-illuminance closed curve above a certain illuminance, and this barycentric position is displayed as the maximum illuminance position on the main optical axis on the monitor TV screen. However, Japanese Patent Application Laid-Open No. 57-179639 discloses an inspection method in which the direction of the headlamp is adjusted so that this display falls within a predetermined window.

(Problems to be Solved by the Invention) However, the shape of the light distribution pattern of the headlamp irradiated on the test screen is different depending on the vehicle type. Therefore, if the barycentric position of the isolux closed curve obtained by image processing the light distribution pattern is the maximum illuminance position, that is, the main optical axis position of the headlamp, if the light distribution pattern is concentric, the main optical axis position is There is no problem because it matches
As shown in FIG. 6, when the main optical axis positions are unevenly distributed in the closed curve L of equal illuminance, the maximum illuminance position Imax and the center of gravity position G do not match. Therefore, the direction of the headlamp should be adjusted accurately. However, the inspection method was not always satisfactory.

The present invention has been made in view of the above points, and an object of the present invention is to provide a main optical axis inspection method for a headlamp, which is capable of accurately obtaining the main optical axis position of the headlamp.

(Means for Solving the Problems) According to the present invention, in order to achieve the above object, a light distribution pattern of a headlamp illuminated on a test screen installed at a predetermined position in front of the vehicle is photographed, and the light distribution pattern After the image is image-processed to determine a first illuminance threshold value at which the first isoilluminance closed curve has a predetermined area, a maximum value and a minimum value in the X and Y coordinate axis directions of the first isoilluminance closed curve are obtained, respectively. Then, the maximum value and the minimum value in each of the X and Y coordinate axis directions are respectively obtained from the second isoilluminance closed curve determined by the second illuminance threshold value which is larger than the first illuminance threshold value by a predetermined amount. Obtaining each coordinate position in the virtual maximum illuminance threshold determined based on the maximum value and the minimum value of both isoilluminance closed curves, the coordinate position, the maximum illuminance position by the main optical axis of the headlamp, the maximum illuminance position is the Test screen The direction of the headlamp is adjusted so that the headlamp falls within a predetermined acceptable range.

(Operation) When two isolux closed curves defined by the first and second two types of illuminance thresholds are used, the main optical axis position of the headlamp is unevenly distributed within the isolux closed curve of the light distribution pattern. Even if there is, the highest illuminance position can be obtained with high accuracy.

(Embodiment) An embodiment of the present invention will be described below in detail with reference to FIGS.

The main optical axis inspection apparatus for carrying out the method of the present invention includes a test screen 3 for irradiating headlamps 1 and 2 for inspection, television cameras 4 (for right) and 5 (for left), a processing device 6 and a monitor television 7 ( Equipped with (for right), 8 (for left).

When a vehicle equipped with the headlamps 1 and 2 arrives at a predetermined inspection position, the left and right headlamps 1 and 2 are turned on as shown in FIG. It is irradiated on the test screen 3 installed in the. The respective light distribution patterns 3a, 3b of the headlamps 1, 2 irradiated on the test screen 3 are photographed by the TV cameras 4, 5, and the photographed light distribution patterns 3a, 3b are binarized by the processing device 6. Image processing such as the above and various arithmetic processing are performed, and the isoilluminance closed curve and the position of the virtual maximum illuminance threshold, which will be described later, are displayed on the monitor televisions 7 and 8 together with a predetermined acceptable range on the test screen 3.

In the present invention, the light distribution patterns 3a, 3b on the test screen 3 are image-processed by the processing device 6 as follows according to the flowchart shown in FIG. 1, and the maximum illuminance of the main optical axis is based on the result. The directions of the headlamps 1 and 2 are adjusted so that the part falls within the predetermined acceptable range. Since the light distribution patterns 3a and 3b on the test screen 3 are similarly image-processed, one light distribution pattern 3a will be described below, and the other light distribution pattern 3b will be omitted.

First, the light distribution pattern 3a taken by the TV camera 4
Image processing such as binarization is performed to obtain an isolux closed curve L ₁ where the area within the isolux closed curve becomes a predetermined area (see FIG. 3), and the illuminance on the closed curve L _{1 at} this time is the illuminance threshold T _L (Step 10). And from this isoilluminance closed curve L ₁ ,
Maximum value X _max = e, Y _max = j in each X, Y coordinate axis direction, and minimum value X
_min = a and Y _min = f are obtained respectively (step 12). still,
The isolux closed curve L ₁ is displayed on the screen of the monitor TV 7.

Next, an illuminance threshold T _U (= T _L + α) larger than the illuminance threshold T _L by a predetermined value α is determined (step 14). Based on this illuminance threshold T _U , the isolux closed curve L ₂ shown in FIG. 3 is obtained in the same manner as described above, and from this isolux closed curve L ₂ , the maximum value X _max = d, Y in the X and Y coordinate axis directions is obtained. _max = i and minimum value X _min = b,
Y _min = fg, respectively calculated (step 16). This isoilluminance closed curve L ₂ is also displayed on the screen of the monitor TV 7.

Then, it is determined whether the set illuminance threshold value T _U is appropriate (step 18). This determination is based on whether or not the difference (= d−b, i−g) between the maximum value and the minimum value in the X and Y coordinate axis directions on the isolux closed curve L ₂ is within a predetermined range. To do.

If the result of step 18 is negative (No), the illuminance threshold
Adjust T _U (step 20) and return to step 16 again. That is, the difference value (d-b) or (i-g) is the illuminance threshold T _U to atmospheric when above this range a large out of the predetermined range, the small illuminance threshold T _U when small, each adjustment To do.

If the result of step 18 is affirmative (Yes), the coordinates of the virtual maximum illuminance position I _max of the light distribution pattern 3a are calculated based on the coordinates of the maximum value and the minimum value obtained by the isoilluminance closed curves L ₁ and L ₂ . Ask (step 22).

That is, as to the coordinate position in the X-axis direction, as shown in FIG. 4, the maximum value (= d, e) and the minimum value (= a, b) in the X-axis direction obtained by the isolux closed curves L ₁ and L ₂ are obtained. ) Is represented on the horizontal axis, and the illuminance thresholds T _L and T _U are represented on the vertical axis, and the maximum value (= d, e) and the minimum value (= a, b) at each illuminance threshold T _L , T _U are excluded. Then, the virtual maximum illuminance position I _max is determined and the coordinate position (= c) in the X-axis direction at this illuminance position I _max is obtained. The virtual maximum illuminance threshold value at this time is T _max in the figure. On the other hand, regarding the coordinate position in the Y-axis direction, as shown in FIG. 5, the values (= f, g, i, j) in the Y-axis direction are plotted on the horizontal axis, and the illuminance thresholds T _L , T _U are plotted on the vertical axis. In the same manner as described above, the maximum value (= i, j) and the minimum value (= f, g) at each illuminance threshold value T _L , T _U are extrapolated to the virtual maximum illuminance position I _max in the Y-axis direction. The coordinate position (= h) of is calculated. The coordinate position (c, h) of this virtual maximum illuminance position I _max is also
It is displayed on the screen of the television 7.

After that, the orientation of the headlamp 1 with respect to the test screen 3 is adjusted (step 24). In adjusting the orientation of the headlamp 1, the coordinate position (c, h) of the virtual maximum illuminance position I _max displayed on the screen of the monitor TV 7 is adjusted.
Is assumed to coincide with the actual maximum illuminance position of the main optical axis of the headlamp 1, so that the coordinate position (c, h) falls within the acceptable range displayed on the screen of the monitor TV 7.
Adjust the orientation with respect to the test screen 3.

As described above, the directions of the headlamps 1 and 2 arranged on both sides of the vehicle body are respectively adjusted, and the main optical axis inspection of the headlamp is completed.

(Effects of the Invention) As is clear from the above description, according to the main optical axis inspection method for a headlamp of the present invention, the light distribution pattern of the headlamp illuminated on the test screen installed at the predetermined position in front of the vehicle is photographed. Then, after the image of the light distribution pattern is image-processed to determine the first illuminance threshold value at which the first isolux closed curve becomes a predetermined area, the maximum of the first isolux closed curve in the X and Y coordinate axis directions is obtained. Then, the maximum value and the minimum value in each of the X and Y coordinate axis directions are calculated from the second isoilluminance closed curve determined by the second illuminance threshold value which is larger than the first illuminance threshold value by a predetermined amount. Obtaining each, after that, each coordinate position in the virtual maximum illuminance threshold determined based on the maximum value and the minimum value of the two isoilluminance closed curves, each coordinate position, as the maximum illuminance position by the main optical axis of the headlamp , The highest illuminance level Since the arrangement of the headlamps is adjusted so that the position falls within a predetermined acceptable range on the test screen, even if the main optical axis positions of the headlamps are unevenly distributed within the isolux closed curve, The main optical axis position can be obtained with high accuracy, and since two closed curves of equal illuminance determined by two types of illuminance thresholds are only used, it is very simple and has an excellent effect.

[Brief description of drawings]

1 to 5 show an embodiment of the present invention, FIG. 1 is a flow chart showing a main optical axis inspection method of a headlamp of the present invention, and FIG. 2 is a main optical axis inspection method of a headlamp. FIG. 3 is a block diagram showing the configuration of the main optical axis inspection device
And the distribution curve diagrams of the second isolux curve, FIG. 4 and FIG.
The figure shows a method of obtaining the virtual maximum illuminance threshold and the coordinate position at the illuminance threshold from the relationship between the maximum and minimum values in the X and Y coordinate axis directions of the isoilluminance closed curve and the first and second illuminance thresholds. The figure shows the maximum and minimum values in the X-axis direction and the first and second values.
5 is a projection view showing the relationship with the illuminance threshold of FIG. 5, FIG. 5 is a projection view in the same Y-axis direction, and FIG. 6 is a distribution curve diagram of an isolux closed curve showing a conventional method for obtaining the maximum illuminance position from the center of gravity of the isolux closed curve. Is. 1,2 …… Headlamp, 3 …… Test screen, 3a, 3b
...... Light distribution pattern, 4 ... TV camera (for right), 5 ...
... TV camera (for left), 6 ... Processing device, 7 ... Monitor TV (for right), 8 ... Monitor TV (for left).

Claims (1)

[Claims] Claim: What is claimed is: 1. A light distribution pattern of a headlamp illuminated on a test screen installed at a predetermined position in front of a vehicle is photographed, and an image of the light distribution pattern is image-processed so that a first isolux closed curve has a predetermined area. After defining the first illuminance threshold,
The maximum value and the minimum value in the X and Y coordinate axis directions of the first isoilluminance closed curve are respectively obtained, and then the second isoilluminance determined by the second illuminance threshold value which is larger than the first illuminance threshold value by a predetermined amount. From the closed curve, the maximum value and the minimum value in each of the X and Y coordinate axis directions are respectively obtained, and thereafter, the respective coordinate positions in the virtual maximum illuminance threshold determined based on the maximum value and the minimum value of the both isoilluminance closed curves are obtained, The coordinate position is set as the maximum illuminance position by the main optical axis of the headlamp, and the orientation of the headlamp is adjusted so that the maximum illuminance position falls within a predetermined acceptable range on the test screen. Main optical axis inspection method for lamps.