JP2001013039A - Headlight tester - Google Patents

Abstract

PROBLEM TO BE SOLVED: To precisely calculate the inclination of the main optical axis of a headlight even when the headlight is not confronted accurately, by a method wherein a screen which diffuses incident light is arranged on the focal plane of a lens on which the light of the headlight is incident. SOLUTION: A screen 2 which diffuses incident light is arranged on the focal plane of a lens L on which the light 5 of a headlight is incident. On the basis of the luminous intensity distribution characteristic of the light 5 of the headlight which appears on the screen 2, a computing and processing means calculates the inclination of the main optical axis of the light 5 of the headlight. Since the screen 2 is arranged on the focal plane of the lens L, the luminous intensity distribution characteristic of the light 5 of the headlight which is image-formed on the screen 2 is not affected by the accuracy of the confrontation of the headlight, and it is affected only by the angle of incidence of the light 5 of the headlight. As a result, the inclination of the main optical axis of the headlight can be calculated on the basis of the luminous intensity distribution characteristic on the screen 2, its calculation result is not affected by the accuracy of confrontation of the headlight, and the labor of the confrontation of the headlight is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a headlight tester, and more particularly, to a headlight tester for measuring the deflection and luminous intensity of a main optical axis of a vehicle headlight.

[0002]

2. Description of the Related Art A headlight tester is widely used for measuring a main optical axis and a luminous intensity of a headlight of a vehicle. FIGS. 6 and 7 show a conventional example of a headlight tester. In FIG. 6, a headlight tester (hereinafter simply referred to as a tester) 50 is provided on a reciprocable rail 51. On the floor surface on which the rails 51 are laid (the traveling surface of the vehicle), two reference lines 52 are provided along a direction perpendicular to the laying direction of the rails 51. The two reference lines 52 are provided in parallel with a vehicle width interval substantially therebetween, and serve as positioning lines when the vehicle 60 enters the tester 50. Reference numeral 53 denotes a mirror for confirming the position of the reference line 52 when the driver enters the vehicle toward the tester 50. FIG. 7 is a diagram when FIG. 6 is viewed from the side of the vehicle 60. The tester 50 includes a tester main body 54 that receives the headlight light of the vehicle, and a support body 57 that supports the tester main body 54 so as to be vertically movable and rotatably up, down, left and right. Wheels that rotate along the rails 51 are provided on the bottom surface of the support 57 so that the support 57 can be moved in the direction in which the rails 51 are laid. The tester main body 54 includes an optical system 5 for receiving light emitted from a headlight 55 of the vehicle 60.
6 for diagnosing whether the light distribution characteristics of the vehicle headlights, the deflection of the main optical axis, and the like are within specified ranges according to the light distribution and luminous intensity of the headlight light captured by the optical system 56. is there. The tester main body 54 can not only reciprocate along the rails 51, but also perform vertical positioning by moving up and down in a direction perpendicular to the floor surface F. In addition, the tester main body 54 is provided so as to be able to rotate a predetermined amount in a vertical direction and a horizontal direction (a predetermined amount of swing is possible) at an arbitrary position positioned in the vertical direction. The direction of the optical axis of the system can be adjusted.

When measuring the light distribution characteristics and the like of a vehicle headlight using this tester 50, a vehicle facing operation and a light facing operation are required as prerequisites. The vehicle facing operation refers to an operation of making the center line (the dashed line in FIG. 6) on the exterior of the vehicle body parallel to the optical axis of the optical system of the tester main body 54. This vehicle facing operation is performed as follows. The driver carefully operates the steering wheel so that the vehicle 60 moves along the reference line 52 while checking the mirror 53, and moves the tip of the vehicle 60 to a distance of, for example, 1 [m] before the tester 50. As a result, the vehicle 60 enters at right angles to the laying direction of the rail 51. Next, the swing of the tester main body 54 is adjusted, and the direction of the optical axis of the built-in optical system is set parallel to the direction of the center line of the vehicle. The swing adjustment operation of the tester 50 is performed while capturing the image of the vehicle into the optical system and checking the image of the vehicle with a scope. Also, Japanese Patent Application Laid-Open No. Hei 8-226
In 873 and the like, a laser beam parallel to the optical axis of the built-in optical system 56 is irradiated on the vehicle body, and the laser beam is scanned in the longitudinal direction of the vehicle body, and the scanning locus of the laser beam coincides with the center line of the vehicle. Thus, the direction of the tester main body 54 is adjusted visually.

When vehicle facing is completed by these methods, a light facing operation is performed next. The light facing operation is an operation of aligning the optical axis of the built-in optical system 56 of the tester 50 with the center of the headlight of the vehicle (the center position of the light emitting surface of the headlight). This operation is performed by taking an image of the headlight into the optical system 56 of the tester main body 54 and positioning the tester 50 such that the center of the headlight shown in the image coincides with the optical axis of the optical system. Note that there are two types of this operation: visually performing the above-described headlight image while checking it with a scope, and automatically performing the right facing by image recognition. Tester 50
Is performed by an operation of moving the tester 50 in the left-right direction of the vehicle along the rail 51 and an operation of moving the tester main body 54 in the vertical direction of the vehicle.

After the vehicle facing and the light facing are completed, the luminous intensity of the headlight and the inclination of the main optical axis are measured.
Hereinafter, the principle of measuring the inclination of the main optical axis of the headlight will be described. 8 and 9, reference numeral H denotes a center point (light source) of the headlight, reference numeral M denotes a main optical axis of the headlight light, and reference numeral L denotes a lens of the tester main body 54. The dashed line indicates the optical axis of the optical system built in the tester main body 54. The distance f is the focal length of the lens L. The inclination of the main optical axis M is determined by the coordinates of the main optical axis on the screen placed at a position A relatively close to the lens L and the main light on the screen placed at a position B farther from the position A as viewed from the lens L. It is calculated based on the direction of the vector formed by the coordinates of the axis.

[0006]

Here, although the inclination (incident angle) of the main optical axis M is the same in FIGS. 8 and 9, FIG.
In the state where the light facing is precisely secured as shown in FIG. 9 and the state where the light facing is not precisely secured as shown in FIG. 9, the coordinates of the main optical axis appearing on the screen at the positions A and B. Are different. For this reason, in the conventional method of measuring the inclination of the main optical axis, it is necessary that the light facing operation is performed precisely, and labor for measurement is spent on the precise operation.

[0007]

SUMMARY OF THE INVENTION The object of the present invention is to improve the disadvantages of the prior art and, in particular, to accurately calculate the inclination of the main optical axis of the headlight even if the writing is not precisely performed. It is an object of the present invention to provide a headlight tester capable of reducing the labor of facing the light.

[0008]

In order to achieve the above object, according to the first aspect of the present invention, there is provided a lens for inputting headlight light, a screen disposed on a focal plane of the lens and diffusing the incident light, And an arithmetic processing unit for calculating the inclination of the main optical axis of the headlight light based on the light distribution characteristics of the headlight light appearing on the screen.

According to the present invention, since the screen is arranged on the focal plane of the lens, the light distribution characteristics of the headlight light formed on the screen are not affected by the accuracy of the light facing, but only the incidence of the headlight light. Only affected by corners.
For this reason, the inclination of the main optical axis of the headlight can be calculated from the light distribution characteristics on the screen, and the calculation result is not affected by the accuracy of facing the light.

Here, the screen diffuses and transmits the incident light, an image pickup means is provided at a destination of the light transmitted through the screen, and the arithmetic processing means outputs the headlight light appearing at the output of the image pickup means. The inclination of the main optical axis of the headlight light may be calculated based on the light distribution characteristics described above.

Alternatively, a half mirror is provided between the lens and a focal plane of the lens, and the screen is arranged at a destination of light reflected by the half mirror,
The screen diffuses and reflects the incident light, and the imaging means is provided at the destination of the light transmitted through the half mirror after being reflected by the screen. The arithmetic processing means includes a headlight appearing at the output of the imaging means. The inclination of the main optical axis of the headlight light may be calculated based on the light distribution characteristics of the light. With these, the above-mentioned object is to be achieved.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIG.
4 through FIG. Here, the same parts as those in the conventional example are denoted by the same reference numerals, and redundant description is omitted.

FIG. 1 is a configuration diagram of an optical system of a headlight tester according to the present invention. The optical system 10 built in the tester main body 54 includes a lens L for receiving headlight light.
And a half mirror 1 arranged on the optical axis of the lens L
And a screen 2 for uniformly diffusing and transmitting the light transmitted through the half mirror 1, and a CCD camera 3 for capturing an image of a surface diffused by the screen 2. Reference numeral 4 denotes a light receiving element that receives light reflected by the half mirror 1, and reference numeral 5 denotes light emitted from a headlight.

More specifically, the lens L is a Fresnel lens having a predetermined curvature and refractive index. The screen 2 is arranged at a position (focal plane) separated from the position of the lens L by the focal length f of the lens L. The light receiving element 4 is attached to a servo mechanism (not shown), and can be displaced in two directions (left and right directions in the drawing and normal directions to the paper surface) orthogonal to the incident optical axis, and is used for detecting luminous intensity.

FIG. 2 is a block diagram of the arithmetic processing means to which the CCD camera 3 is connected. The output of the CCD camera 3 is A /
The data is input to the control unit 6 via the D converter 11. The control unit 6 includes a storage unit 7 and a display unit 8. The control unit 6 includes a microcomputer, and sequentially executes a prepared program to calculate the inclination θ of the main optical axis of the headlight based on the light distribution characteristics captured by the CCD camera 3. The storage unit 7 is, for example, a ROM and a RAM,
A parameter α required for calculating the inclination θ of the main optical axis is stored in advance. The display unit 8 is a liquid crystal display or the like.

The controller 6 calculates the inclination θ of the main optical axis of the headlight based on the following principle. In this embodiment,
The diffusion screen 2 is arranged on the focal plane of the lens L,
The light distribution characteristics of the headlight appearing on the diffusion screen are imaged by the CCD camera 3. FIG. 3 shows the relationship of this optical system.
Shown in As shown in FIG. 3, when the screen 2 is arranged on the focal plane of the lens L, if the inclination of the main optical axis M incident on the lens L is equal, the focal point is focused on the same position on the screen 2 regardless of the incident position. For this reason, even if precise facing of the light is not performed, the focal position on the screen 2 is not affected, and only the inclination of the main optical axis M affects the focal position on the screen 2. As shown in FIG. 4, the main optical axis M has an inclination θ
Is assumed, the imaging position on the screen 2 is shifted from the reference position by d. At this time, the inclination θ of the main optical axis
There is a relationship between the following equation (1) and (2) between and the shift d of the focal position.

[0017]

(Equation 1)

The above equation can be derived as follows.
The three main optical axes M depicted in FIG. 4 are parallel to each other, and focus on the same position on the screen 2 as described above. Focusing on the lowermost main optical axis M, the main optical axis M enters the center of the lens L, proceeds straight, and reaches the screen 2 as it is. Therefore, it is clear that the relationship of d = f · tan θ holds. The control unit 6 performs predetermined image processing such as binarization on the light distribution characteristics on the screen 2 captured by the CCD camera 3 to extract a main optical axis, calculates coordinates on the screen, and calculates reference coordinates. Is calculated. The proportional coefficient α is read from the storage unit 7, and the inclination θ of the main optical axis is calculated based on the above equation (2). Then, the value of the inclination θ is displayed on the display unit 8.

As described above, according to the present embodiment, the diffusion screen is provided on the focal plane of the lens L, and the inclination of the main optical axis of the headlight is determined based on the light distribution characteristics connected to this screen. The accuracy of the light facing does not affect the light distribution characteristics on the screen, eliminating the need for precise light facing operations for determining the inclination of the main optical axis, reducing the measurement effort and improving reliability. High measurement values can be obtained. As long as the lens is facing such that most of the light beam emitted from the headlight is received by the lens, no more precise light facing operation is required. Further, since the light transmitted through the screen is imaged by the CCD camera, the optical path from the screen to the CCD camera can be made relatively short, and the occurrence of measurement errors in this section can be suppressed. Further, since a finder and a screen (for a monitor) for directly facing headlights, which are generally provided in conventional models, are not required, a tester can be provided at a low cost, and it is hardly affected by external light, and reproducibility is reduced. Good measurements can be made.

Next, a modification of the above embodiment will be described with reference to FIG. Here, the same parts as those of the previous embodiment are denoted by the same reference numerals, and redundant description will be omitted. In the optical system 20 according to the present embodiment, the light receiving element 4 is disposed at the destination of the light transmitted through the half mirror 1 and the screen uniformly diffuses and reflects the incident light at the destination of the light reflected by the half mirror 1. 9 were arranged. Also, this screen 9
Then, the CCD camera 3 is opposed to the camera via the half mirror 1, and an image of the surface appearing on the screen 9 is picked up by the CCD camera 3. Then, the screen 9 was arranged on the focal plane of the lens L by matching the optical path length from the lens L to the screen 9 with the focal length of the lens L. The configuration of the arithmetic processing means connected to the CCD camera 3 is the same as in the previous embodiment. Even with such a configuration, the same operation and effect as those of the first embodiment can be obtained, and the length of the optical system 20 in the depth direction (the left-right direction in FIG. 5) can be reduced as compared with the first embodiment. The size of the tester body can be reduced.

Here, the present invention is not limited to the above embodiments, but arranges a screen on the focal plane of the lens and calculates the inclination of the main optical axis of the headlight from the light distribution characteristics appearing on the screen. I just need.

[0022]

The present invention is constructed and functions as described above. According to this, a diffusion screen is provided on the focal plane of the lens, and the main light of the headlight is determined based on the light distribution characteristics tied to this screen. Since the tilt of the axis is determined, the accuracy of the light facing does not affect the focal position on the screen,
Precise light facing operation is not required for determining the inclination of the main optical axis, reducing the measurement effort,
Highly reliable measurement values can be obtained. As long as the lens is facing such that most of the light beam emitted from the headlight is received by the lens, no more precise light facing operation is required. Also, since the finder and screen (for monitor) directly facing the headlights, which are generally equipped in the conventional model, are not required, the tester can be provided at a low cost, and is less affected by external light, and the reproducibility is reduced. Good measurements can be made.

According to the second aspect of the present invention, since the light transmitted through the screen is imaged by the image pickup means, the optical path from the screen to the image pickup means can be made relatively short.
Generation of a measurement error in this section can be suppressed.

Furthermore, according to the third aspect of the present invention, since the screen and the image pickup means are opposed to each other with the half mirror interposed therebetween, the length of the optical system in the depth direction (the left-right direction in FIG. 5) can be made relatively short. Thus, it is possible to provide an unprecedented superior headlight tester that can reduce the size of the tester main body.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an optical system according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of an arithmetic processing unit according to an embodiment of the present invention.

FIG. 3 is an explanatory diagram for explaining a measurement principle of a headlight main optical axis according to the present invention.

FIG. 4 is an explanatory diagram for explaining a measurement principle of a headlight main optical axis according to the present invention.

FIG. 5 is a configuration diagram of an optical system according to another embodiment of the present invention.

FIG. 6 is an explanatory diagram of a conventional example.

FIG. 7 is an explanatory diagram of a conventional example in which FIG. 6 is viewed from a side of a vehicle.

FIG. 8 is an explanatory diagram for explaining a measurement principle of a headlight main optical axis according to a conventional example.

FIG. 9 is an explanatory diagram for explaining a problem of a conventional example.

[Explanation of symbols]

 Reference Signs List 1 half mirror 2, 9 screen 3 CCD camera (imaging means) 6 control unit 7 storage unit 8 display unit 10, 20 optical system d shift amount of focus on screen from reference position f focal length H center point L of headlight L Lens M Headlight main light axis α Proportional coefficient θ Main light axis inclination

Claims (3)

[Claims] 1. A lens for entering headlight light,
A screen arranged on the focal plane of the lens for diffusing incident light; and an arithmetic processing means for calculating a tilt of a main optical axis of the headlight based on a light distribution characteristic of the headlight appearing on the screen. A headlight tester characterized in that: 2. The apparatus according to claim 1, wherein the screen diffuses and transmits the incident light, an image pickup unit is provided at a destination of the light transmitted through the screen, and the arithmetic processing unit includes a headlight light appearing at an output of the image pickup unit. The headlight tester according to claim 1, wherein the inclination of the main optical axis of the headlight light is calculated based on the light distribution characteristics of (1). 3. A half mirror is provided between the lens and the focal plane of the lens, and the screen is arranged at a destination of light reflected by the half mirror, and the screen diffuses and reflects incident light. Imaging means is provided at a destination of the light transmitted through the half mirror after being reflected by the screen, and the arithmetic processing means is configured to perform a calculation based on a light distribution characteristic of headlight light appearing in an output of the imaging means. The headlight tester according to claim 1, wherein the inclination of the main optical axis of the headlight light is calculated by the calculation.