Headlamp leveling test method

Abstract

To provide a headlamp leveling test method that measures the vertical variation of a downward beam headlamp with a certain degree of accuracy and easily determines the measurement results.SOLUTION: In a headlamp leveling test method according to the present invention, a test system capable of projecting a light distribution pattern of a downward beam onto a screen and photographing the light distribution pattern with a camera is used. A control device constituting the test system performs for each loading condition the steps of: cropping image data within a specific cropping range; creating an illuminance distribution map of the cropped image data; extracting a contour line of a specific brightness from the illuminance distribution map; and converting each pixel forming the extracted contour line into coordinates of the cropped image data. The displacement amount of the contour lines extracted under other loading conditions is calculated relative to a reference contour line, and it is confirmed whether all the displacement amounts are within a specified range.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a headlamp leveling test method for measuring and determining vertical variations in dipped beam headlamps. [Background technology]

[0002] Vehicle headlamps (headlights) are required to be tested to determine whether their light distribution pattern (specifically, the light distribution pattern of low beam headlights for passing vehicles) is within the standard range set out in vehicle safety standards.

[0003] Therefore, in the certification process for automobile development, after the headlamps are installed, low beams are projected onto the front screen to test whether the clear boundary line (hereinafter referred to as the cut-off line) of the low beams falls within a specified standard range. In other words, headlamp leveling tests have traditionally been carried out in the certification process for automobile development.

[0004] Such headlamp leveling tests have traditionally been performed visually, but there are limitations to how much inspection accuracy can be improved, and the tests also cause significant fatigue and strain on the eyes of the operators. This has led to a demand for automation, and development of such methods has been underway for some time.

[0005] For example, Patent Document 1 describes, as an example of a headlamp leveling test, that the light distribution pattern projected from the headlamp onto a screen is photographed using a camera or the like, the photographed image is subjected to image processing to determine the elbow point of the cutoff line, and whether this elbow point is located within a predetermined standard range (whether the amount of deviation of the elbow point when projected at a predetermined distance ahead is within a predetermined range). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-79359 Summary of the Invention [Problem to be solved by the invention]

[0007] However, images of light distribution patterns captured by cameras, etc. contain noise in each pixel, which causes the cutoff line to become unstable due to changes in brightness values ​​near the edges, making it impossible to stably obtain the elbow point on the image.

[0008] Therefore, there is a demand for a method (headlamp leveling test method) that can accurately test whether the light distribution pattern of a vehicle's headlamp is within the standard range defined by the vehicle safety standards, without relying on elbow points detected by detailed processing such as the elbow point detection method described in Patent Document 1.

[0009] The present invention has been made in consideration of the above-mentioned problems, and aims to provide a headlamp leveling test method that measures the vertical fluctuation of a dipped beam headlamp with a certain degree of accuracy and easily judges the measurement results. [Means for solving the problem]

[0010] The headlamp leveling test method of the present invention is a headlamp leveling test method that uses a test system that projects the light distribution pattern of a downward beam emitted from a headlamp onto a screen and can photograph the light distribution pattern projected onto the screen with a camera, and a control device that constitutes the test system measures the amount of vertical fluctuation of the headlamp for each loading condition based on image data of images photographed for different loading conditions, and judges the measurement results.

[0011] In detail, the control device executes, for each loading condition, an image cutting step of cutting out image data in a specific cutting range, an illuminance distribution creation step of creating an illuminance distribution map of the cut-out image data, a contour line extraction step of extracting contour lines of specific brightness from the illuminance distribution map, and a coordinate conversion step of converting each pixel forming the extracted contour lines into the coordinates of the cut-out image data and recording all coordinates.

[0012] Then, when the contour lines extracted under the standard loading conditions among the loading conditions are set as the reference contour lines, the control device calculates the amount of displacement of the contour lines extracted under other loading conditions relative to the reference contour lines as the fluctuation amount, and checks whether all of the displacement amounts are within the specified range.

[0013] According to the headlamp leveling test method of the present invention, the vertical fluctuation of a dipped beam headlamp can be measured with a certain degree of accuracy, and the measurement results can be easily judged.

[0014] In the headlamp leveling test method according to the present invention, it is preferable that the specific cut-out range is arranged so that the boundary between light and dark in the light distribution pattern under the standard load condition is near the center in the height direction and includes an elbow point.In the headlamp leveling test method according to the present invention, it is preferable that the displacement amount be the difference between the average value of the coordinate values ​​in the height direction of the standard contour line and the average value of the coordinate values ​​in the height direction of the contour lines extracted under other load conditions. [Effects of the Invention]

[0015] According to the headlamp leveling test method of the present invention, the vertical fluctuation of a dipped beam headlamp can be measured with a certain degree of accuracy, and the measurement results can be easily judged. [Brief explanation of the drawings]

[0016] [Figure 1]FIG. 1 is a top view schematically showing the configuration of a test system when carrying out a headlamp leveling test method according to the present invention. [Figure 2] FIG. 2 is a diagram illustrating an example of the hardware configuration of a computer that operates as a control device. [Figure 3] FIG. 3 is a flowchart showing a headlamp leveling test method according to the present invention. [Figure 4] FIG. 4 is a diagram showing an image of the image cutting process. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, an embodiment of a headlamp leveling test method according to the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to this embodiment. Furthermore, in the specification and drawings of the present application, elements that can be similarly described may be designated by the same reference numerals, and duplicated description may be omitted.

[0018] An embodiment of a headlamp leveling test method according to the present invention will be described in detail with reference to FIGS.

[0019] <System configuration> Fig. 1 is a top view showing a schematic configuration of a test system for carrying out a headlamp leveling test method according to the present invention. In Fig. 1, the test system 1 of this embodiment includes a vehicle 11 including a right headlamp 11a and a left headlamp 11b, a screen 12 disposed in front of the vehicle 11 for projecting downward beams (light distribution patterns) emitted from the headlamp, a camera 13 for capturing images of the light distribution pattern projected on the screen 12, and a control device 14 connected to the camera 13 wirelessly or by wire and for executing a program for a headlamp leveling test based on image data obtained from the camera 13.

[0020] In the headlamp leveling test method of this embodiment, the above-mentioned test system 1 is used to measure the vertical fluctuation amount of a vehicle's downward beam headlamp for each loading condition with a certain accuracy, and the measurement results are judged (results of OK or NG are obtained).

[0021] A light distribution pattern of downward beams emitted from each headlamp of the vehicle 11 is projected onto the screen 12. In the light distribution pattern projected onto the screen 12, there is a large difference in brightness at the boundary between the bright area hit by the irradiated light and the dark area not hit by the irradiated light (border area between light and dark), and a cut-off line (clear boundary line) is generated in this area. The distance L from the screen 12 to the reference center of each headlamp (11a, 11b) is at least 10 m.

[0022] The camera 13 is a digital camera capable of capturing high-precision images, such as a CCD (Charge Coupled Device) camera. In this embodiment, the headlamp leveling test is performed using two cameras: a right camera 13a that captures the light distribution pattern emitted from the right headlamp 11a, and a left camera 13b that captures the light distribution pattern emitted from the left headlamp 11b. The right camera 13a and the left camera 13b are identical cameras so that the capturing conditions are consistent for each headlamp, and are arranged at positions symmetrical left and right with respect to the center line A in the longitudinal direction of the vehicle 11.

[0023] In this embodiment, two cameras 13 are used, but one camera 13 may be arranged alternately on the left and right, and the headlamp leveling test may be performed on each camera. Also, one camera 13 may be fixed above the center line A of the vehicle 11, and the headlamp leveling test may be performed.

[0024] <Control device> 2 is a diagram showing an example of the hardware configuration of a computer that operates as the control device 14 that executes a program for a headlamp leveling test. The control device 14 functions as a host computer when carrying out the headlamp leveling test method of this embodiment.

[0025] 2, the control device 14 includes a control unit 21 including a logic circuit such as a CPU (Central Processing Unit), a storage unit 22 including various memories, an input unit 23 including a user interface such as a keyboard and a mouse, an interface (I / F) unit 24 that performs input / output processing such as printing and scanning, a display unit 25 that is a display, and a communication unit 26 that communicates with the outside (such as the camera 13) via a predetermined network. Note that, although the control device 14 includes the input unit 23 including a user interface such as a keyboard and a mouse in FIG. 2, the control device 14 is not limited to this, and may be configured without the input unit 23 or may be configured to use the input unit 23 together with the input unit 23 by providing the display unit 25 with a touch panel function.

[0026] 2, in order to carry out the headlamp leveling test method of this embodiment, control unit 21 executes a headlamp leveling test program (hereinafter referred to as a test program) which involves a series of processes such as image processing of image data obtained from camera 13 and determination of test results. Storage unit 22 stores the test program and various information (contents of loading conditions 1 to 6 described below, illuminance information (256 levels), specific brightness, specified ranges, etc.), as well as various data obtained during the processing (current loading condition (one of loading conditions 1 to 6), illuminance distribution map, coordinate information of contour lines, displacement of contour lines, etc.). Control unit 21 carries out the headlamp leveling test method of this embodiment by reading out the test program stored in storage unit 22.

[0027] Note that the storage unit 22 is not limited to an internal memory, and may be an external storage medium such as a DVD (Digital Versatile Disc) or an SD memory, or may be configured with both an internal memory and an external storage medium (such as a DVD or an SD memory). Also, for the sake of convenience of explanation, the hardware configuration of the control device 14 lists the configuration related to the implementation of the headlamp leveling test method of this embodiment, and does not represent all the functions of the computer that constitutes the control device 14.

[0028] Furthermore, the control device 14 is assumed to be a general-purpose PC such as a desktop personal computer or a notebook computer, but is not limited to these and may be, for example, a mobile terminal such as a smartphone or a tablet terminal.

[0029] <Headlamp leveling test> Next, the headlamp leveling test method of this embodiment will be specifically explained according to a flowchart. This test complies with the "Japan Automobile Standards Internationalization Center" Regulation No. 48, "Uniform Provisions for the Approval of Vehicles Relating to the Installation of Lamps and Light Signaling Devices." The headlamp leveling test described below is performed within the scope of application of Supplementary Provision 6, "Measurement of Variation in Down Beam Inclination as a Function of Load." The loading conditions (loading conditions 1 to 6) for the headlamp leveling test are shown in Table 1.

[0030] [Table 1]

[0031] The above regulations also clearly define the initial value of the tilt (optical axis) of the downward beam. In this embodiment, the initial value of the optical axis is 0.57°, which is within the specified range. The initial value of the optical axis is the tilt of the downward beam measured under loading condition 1.

[0032] In the headlamp leveling test method of this embodiment, when the inclination of the downward beam varies depending on the loading conditions, the amount of displacement of the light distribution pattern under other loading conditions (loading conditions 2 to 6) relative to the light distribution pattern (initial position) projected onto the screen 12 under loading condition 1 is measured, and it is determined whether each amount of displacement is within a specified range (OK if it is within the range, NG if it is outside the range).

[0033] FIG. 3 is a flowchart showing the headlamp leveling test method of this embodiment. The processing flow of the headlamp leveling test method of this embodiment will be described below with reference to the flowchart shown in FIG. 3. For convenience of explanation, this embodiment will describe a case where a test is performed on the right headlamp 11a, but it is assumed that the same processing is performed on the left headlamp 11b. It is also assumed that "loading condition 1" is stored in the memory unit 22 before the test as the initial value of the loading condition.

[0034] First, as a preliminary process, the vehicle 11 is placed in a state of loading condition 1 (see Table 1), and as shown in Fig. 1, the light distribution pattern emitted from the right headlamp 11a is projected onto the screen 12, and the right camera 13a captures the light distribution pattern projected onto the screen 12. The right camera 13a is connected to the control device 14, and image data is transferred from the right camera 13a to the control device 14.

[0035] After the above-described preliminary processing is performed, the control unit 21 of the control device 14 shown in FIG. 2 executes the processing shown in FIG. 3. Specifically, when the control unit 21 receives image data from the right camera 13a via the communication unit 26 (step S1, Yes) while waiting for data reception (step S1, No), the control unit 21 performs processing to crop the image data into a specific cropping range (step S2). FIG. 4 is a diagram illustrating an image cropping process. In this embodiment, the specific cropping range is a rectangle with a width of 300 mm and a height of 500 mm, and the cropping range is positioned so that the boundary between light and dark in the light distribution pattern of the right headlamp 11a under loading condition 1 is located near the center of the cropping range in the height direction. In this case, it is desirable for the cropping range to include the elbow point. The approximate position of the elbow point in the light distribution pattern projected on the screen 12 can be visually recognized.

[0036] Thereafter, the control unit 21 creates an illuminance distribution map of the extracted image data (step S3) and extracts contour lines of a specific brightness from this illuminance distribution map (step S4). Specifically, contour lines of a specific brightness are extracted from the boundary between the bright area where the irradiated light hits and the dark area where the irradiated light does not hit (the area corresponding to the cutoff line). Hereinafter, the contour lines extracted under loading condition 1, which is the reference loading condition (reference loading condition), will be referred to as "reference contour lines." Note that the illuminance distribution map is a step-by-step numerical representation of the brightness (brightness) of each pixel of the image data, which is classified into 256 steps (brightness: 0 (darkest) to 255 (brightest)), as an example. In this embodiment, as an example, a contour line of brightness 120 is extracted.

[0037] Thereafter, the control unit 21 calculates the coordinates (X N , Y N ), and all the coordinates are recorded in the storage unit 22 (step S5). Note that N (= 1 to n) is a natural number.

[0038] Then, the control unit 21 checks whether the loading condition stored in the memory unit 22 is "loading condition 6", and if it is other than "loading condition 6", it increments the loading condition (step S7) and transitions to a state waiting to receive data (step S1, N). Here, since the loading condition stored in the memory unit 22 is the initial value "loading condition 1", the control unit 21 updates the loading condition stored in the memory unit 22 to "loading condition 2" (step S7) and transitions to a state waiting to receive data (step S1, No).

[0039] Thereafter, the loading condition state of the vehicle 11 is changed in the order of loading condition 2, loading condition 3, ..., loading condition 6, and each time a change is made, the light distribution pattern is photographed in the above-mentioned "pre-processing" for the loading condition at that time. Each time the loading conditions are changed, the control device 14 executes the processes of steps S1 to S7 for each loading condition at that time.

[0040] In step S6, if the loading condition stored in the memory unit 22 is "loading condition 6" (step S6, Yes), the control unit 21 then calculates the amount of displacement of the contour lines extracted under other loading conditions relative to the reference contour lines (step S8).

[0041] Specifically, the control unit 21 receives the Y coordinate values ​​(Y1, Y2, . . . , Y n ) and calculate the average value Y1(=(Y1+Y2+...+Y n ) / n). In addition, the control unit 21 calculates the Y coordinate values ​​(Y1, Y2, ..., Y n ) are all read out from the storage unit 22, and the average value Y2 (=(Y1+Y2+...+Y n ) / n) is calculated. Similarly, for the contour lines extracted under loading conditions 3 to 6, all Y coordinate values ​​are read out and their average values ​​Y3, Y4, Y5, and Y6 are calculated. Then, the differences between the average value Y1 and the other average values, i.e., Y1-Y2, Y1-Y3, Y1-Y4, Y1-Y5, and Y1-Y6, are calculated, and these results are used as the displacements of the other contour lines (each of the contour lines extracted under loading conditions 2 to 6) relative to the reference contour line.

[0042] Then, the control unit 21 checks whether all the displacement amounts calculated in step S8 are within a specified range (step S9). The specified range is set in advance so as to satisfy the provisions of Supplementary Provision 6 described above.

[0043] For example, if all the displacement amounts calculated in step S8 are within the specified range (step S9, Yes), the control unit 21 displays on the display unit 25 a message that the test result is OK and the displacement amounts of the other contour lines relative to the reference contour line, and ends the process (step S10). On the other hand, if any of the displacement amounts is not within the specified range (step S9, No), the control unit 21 displays on the display unit 25 a message that the test result is NG and the displacement amounts of the other contour lines relative to the reference contour line, and ends the process (step S11).

[0044] In this embodiment, steps S1 to S5 are executed individually for loading condition 1, ..., loading condition 6, and then the displacement amount calculation process (step S8) and the determination process (steps S9 to S11) are executed, but this is not limited to this. For example, steps S1 to S5 may be executed under loading condition 1, then steps S1 to S5 may be executed under loading condition 2, and then the displacement amount calculation process for the contour lines extracted under loading condition 2 may be executed, and thereafter the displacement amount calculation process may be executed for each loading condition while incrementing the loading condition. In this case, the determination process may be executed individually for loading conditions 2 to 6, or may be executed collectively after all the displacement amount calculation processes for each loading condition have been executed.

[0045] As described above, in the headlamp leveling test method of this embodiment, the light distribution pattern of the downward beam emitted from the headlamp (right headlamp 11a, left headlamp 11b) is projected onto the screen 12, and the test system 1 is capable of capturing an image of the light distribution pattern projected onto the screen 12 with the camera 13. The control device 14 (control unit 21) that constitutes the test system 1 measures the amount of vertical fluctuation of the headlamp for each loading condition based on image data of the images captured for different loading conditions, and judges the measurement results.

[0046] In detail, the control device 14 (control unit 21) executes an image cutting step (step S2) for cutting out image data in a specific cutting range for each loading condition, an illuminance distribution creation step (step S3) for creating an illuminance distribution map of the cut-out image data, a contour line extraction step (step S4) for extracting contour lines of specific brightness from the illuminance distribution map, and a coordinate conversion step (step S5) for converting each pixel forming the extracted contour lines into the coordinates of the cut-out image data and recording all coordinates.

[0047] Then, when the contour lines extracted under the standard loading condition (loading condition 1) among the loading conditions (loading conditions 1 to 6) are used as the reference contour lines, the control device 14 (control unit 21) calculates the amount of displacement of the contour lines extracted under other loading conditions relative to the reference contour lines as the fluctuation amount, and checks whether all the displacement amounts are within the specified range.

[0048] According to the headlamp leveling test method of this embodiment, the vertical fluctuation of a dipped beam headlamp can be measured with a certain degree of accuracy, and the measurement results can be easily judged.

[0049] In the headlamp leveling test method of this embodiment, it is preferable that the specific cut-out range is positioned so that the boundary between light and dark in the light distribution pattern under the standard load condition is near the center in the height direction, and includes the elbow point.

[0050] Furthermore, in the headlamp leveling test method of this embodiment, it is preferable that the displacement amount be the difference between the average value of the coordinate values ​​in the height direction of the reference contour line and the average value of the coordinate values ​​in the height direction of the contour lines extracted under other loading conditions. [Explanation of symbols]

[0051] 1 Test System 11 vehicles 11a Right headlamp 11b Left headlamp 12 screens 13 Camera 13a Right camera 13b Left camera 14 Control device 21 Control Unit 22 Memory section 23 Input section 24 Interface (I / F) section 25 Display section 26 Communications Department

Claims

1. A headlamp leveling test method using a test system that projects a light distribution pattern of a downward beam emitted from a headlamp onto a screen and captures the light distribution pattern projected on the screen with a camera, wherein a control device constituting the test system measures a vertical fluctuation amount of the headlamp for each loading condition based on image data of images captured under different loading conditions, and determines the measurement results, For each loading condition, an image cropping step of cropping image data in a specific cropping range; an illuminance distribution creating step of creating an illuminance distribution map of the extracted image data; a contour line extraction step of extracting a contour line of a specific brightness from the illuminance distribution map; a coordinate conversion step of converting each pixel forming the extracted contour line into coordinates of the extracted image data and recording all coordinates; Run The contour lines extracted under the standard loading conditions among the loading conditions are set as standard contour lines, Calculating the displacement of the contour lines extracted under other loading conditions relative to the reference contour line as the fluctuation amount, and confirming whether all the displacement amounts are within a specified range. A headlamp leveling test method comprising:

2. The specific cut-out range is arranged so that the boundary portion between light and dark of the light distribution pattern under the reference loading condition is near the center in the height direction, and includes an elbow point.

2. The headlamp leveling test method according to claim 1, wherein:

3. The displacement is defined as the difference between the average value of the coordinate values ​​in the height direction of the reference contour line and the average value of the coordinate values ​​in the height direction of the contour lines extracted under other loading conditions.

2. The headlamp leveling test method according to claim 1, wherein:

Images