JP2011079359A - Method and device for detecting elbow point of light distribution pattern - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and a device for detecting an elbow point of a light distribution pattern, which is simplified in processing so as to quickly detect the elbow point, thereby facilitating an optical axis inspection and an optical axis adjustment of a headlamp. <P>SOLUTION: The elbow point detecting device 2 captures an image of the light distribution pattern of the headlamp HL, so as to obtain luminous intensity data, and detects the elbow point where the horizontal cut line and the oblique cut line of the light distribution pattern intersect with each other, using the luminous intensity data. This device includes: a filter processing means 21 removing microscopic fluctuation and noise in a luminous intensity distribution, obtained by detecting, along the horizontal direction, the vertical luminous intensity distribution of the light distribution pattern; an edge processing means 22 enhancing the contrast of the luminous intensity data subjected to the filter processing; and an elbow point detecting means 23 detecting the boundary based on the luminous intensity data subjected to the edge processing, and calculating the vertical position of the boundary in the horizontal direction. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method and a detection device for detecting an elbow point of a light distribution pattern used when adjusting an optical axis of a headlamp of a vehicle such as an automobile.

  As one of the light distributions of the headlamp of an automobile, there is a so-called low beam light distribution for preventing a dazzling oncoming vehicle and illuminating a wide area in front of the vehicle. For example, the light distribution pattern PL of the low beam distribution shown in FIG. 2 is the oncoming vehicle side horizontal cut line CLH formed in the region illuminating the oncoming lane OL and the own vehicle side formed in the region illuminating the own lane SL. The light distribution pattern is composed of the oblique cut line CLS. The point where the oncoming vehicle side horizontal cut line CLH and the host vehicle side oblique cut line CLS intersect is called an elbow point EP. Normally, the elbow point EP is on the vertical line V of the light distribution pattern from the horizontal line H. Also, the optical axis of the headlamp is adjusted so as to be slightly lower. Therefore, when adjusting the optical axis of the headlamp, it is necessary to detect the elbow point in the light distribution pattern.

  Various methods have been conventionally proposed as a method for detecting an elbow point, and one of them is a technique described in Patent Document 1. In this technique, first, a horizontal line corresponding to a horizontal cut line is obtained from the illuminance distribution in the vertical direction in the oncoming vehicle side region of the light distribution pattern. Next, the coordinate position on the oblique cut line is obtained from the vertical illuminance distribution in the vehicle-side region of the light distribution pattern, and an oblique angle line is obtained from this coordinate position and a known inclination angle of the oblique cut line. Accordingly, this is a method of detecting the intersection of the horizontal line and the oblique angle line as an elbow point. In the technique of this patent document 1, it is possible to easily perform the optical axis position inspection and optical axis adjustment of the headlamp using the elbow point, and to shorten the inspection time.

Japanese Patent No. 3939866

  In the technique of the cited document 1, when the oblique cut line necessary for detecting the elbow point is obtained, the inclination angle of the oblique cut line is required as a constant at the time of calculation. Therefore, when detecting the elbow point of the headlamp with a different inclination angle of the oblique cut line, it is necessary to input the inclination angle as a calculation constant to the detection device each time, and the operation becomes troublesome. When an incorrect tilt angle is input, the elbow point is erroneously detected. Even when the correct tilt angle is entered, the design tilt angle set for the headlamps and the actual tilt angle in the light distribution pattern irradiated to the projection screen due to factors such as lens aberration and light source position shift Since an error is unavoidable between the two, the error also occurs in the detection position of the oblique angle line detected using the designed inclination angle and the elbow point obtained therefrom. In order to eliminate this error, it is only necessary to detect the elbow point after measuring the tilt angle of the oblique angle line in the actual light distribution, but a new additional process for measuring this tilt angle is required, The elbow point detection is complicated and takes time.

  The object of the present invention is to simplify the process and quickly detect the elbow point without using the inclination angle of the oblique cut line, and to easily perform the optical axis inspection and optical axis adjustment in the headlamp. An elbow point detection method and a detection apparatus for a light distribution pattern that make it possible to provide a light distribution pattern are provided.

  In the elbow point detection method of the present invention, the light distribution pattern of light emitted from the vehicle headlamp is imaged to acquire light intensity data, and the horizontal cut line and the oblique cut line of the light distribution pattern are obtained from the acquired light intensity data. An elbow point detection method for detecting intersecting elbow points, the step of sequentially detecting the light intensity distribution in the vertical direction of the light distribution pattern as light intensity data along the horizontal direction of the light distribution pattern, A step of performing filtering to remove noise, a step of performing edge processing to increase the contrast at the boundary between the low light intensity region and the high light intensity region of the filtered light intensity data, and the edge processed light intensity data Based on the detected boundary and the vertical position of the detected boundary is calculated along the horizontal direction. Characterized in that it comprises a step of detecting the elbow point on the basis of 置変 reduction.

Here, the filtering process is a process of moving and averaging the luminous intensity data along the vertical direction, and the edge process is a process of binarizing the luminous intensity data with a predetermined threshold value.

  The elbow point detection device for a light distribution pattern according to the present invention images a light distribution pattern of light emitted from a vehicle headlamp, and at least shows a light intensity distribution in the vertical direction of the light distribution pattern along the horizontal direction of the light distribution pattern. And an elbow point detecting device for detecting an elbow point where a horizontal cut line and an oblique cut line of a light distribution pattern intersect from the acquired light intensity data. Is a filter processing unit that performs filtering to remove minute fluctuations and noise in the luminous intensity distribution, and an edge that performs processing to increase the contrast at the boundary between the low luminous intensity area and the high luminous intensity area of the filtered luminous intensity data The processing unit and the vertical direction of the detected boundary are detected based on the luminous intensity data with enhanced contrast. Position is calculated along the horizontal direction, characterized in that it comprises a elbow point calculation unit that detects the elbow point on the basis of the vertical position change of the boundary.

  Here, the image pickup means includes an image pickup element in which a large number of light receiving cells are arranged in an XY matrix as an image pickup pixel, and the elbow point detection device acquires light intensity data of pixel columns arranged in the Y direction while sequentially moving in the X direction. The filter processing unit and the edge processing unit perform processing in the Y-direction luminous intensity distribution in the filter processing unit and the edge processing unit, and the elbow point calculation unit calculates the boundary position in the Y direction and the boundary position in the Y direction. Are sequentially calculated along the X direction, and the Y direction position and the X direction position of the elbow point are detected based on the change in the Y direction of the boundary position.

The elbow point detection device of the present invention is integrally assembled with an optical axis adjustment device for adjusting the optical axis of a vehicle headlamp, and the optical axis adjustment is performed based on the elbow point detected by the elbow point detection device. The optical axis is adjusted by the apparatus.

  According to the present invention, noise or the like is removed by relaxing the change in the luminous intensity data of the light distribution pattern imaged by the imaging device in the filter processing unit, and the contrast of the luminous intensity data is enhanced in the edge processing unit to clearly define the light / dark boundary. Make things. Accordingly, the elbow point calculation unit can obtain an oblique cut line from the horizontal cut line from the coordinate movement locus indicating the boundary, and detect the coordinate point where both of them change, that is, the elbow point. Therefore, when detecting the elbow point, the inclination angle of the oblique cut line as in Patent Document 1 is not necessary, and the operation at the time of detection can be simplified and the elbow point can be detected quickly. Moreover, there is no case where an elbow point is erroneously detected by inputting an incorrect inclination angle. Furthermore, even when there is an error between the designed tilt angle set for the headlamp and the actual tilt angle, the elbow point can be detected accurately. Thereby, an easy and quick optical axis adjustment is realizable.

The conceptual diagram of the headlamp optical-axis adjustment apparatus to which this invention is applied. The light distribution pattern figure of a low beam lamp. Schematic which looked at the headlamp from the back side. The block diagram of an optical axis adjustment apparatus. The schematic diagram of the imaging screen which imaged the light distribution pattern. The figure of the luminous intensity data of the Y direction for detecting an elbow point. The figure of the luminous intensity data of the X direction of the boundary for detecting an elbow point.

  Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a conceptual diagram in which the present invention is applied to an automobile headlamp optical axis adjusting device OCD. An automobile CAR equipped with a headlamp HL whose optical axis is adjusted is set to face the projection screen SC, and projects the light emitted when the headlamp HL is turned on onto the projection screen SC. Here, since the headlamp HL is configured as a low beam lamp, the projection screen SC includes an oncoming vehicle side horizontal cut line, an own vehicle side horizontal cut line CLH, and an oblique cut line CLS, as shown in FIG. The light distribution pattern PL of the low beam light distribution is irradiated.

  The headlamp optical axis adjustment device OCD includes an image pickup device 1 that picks up an image of the light distribution pattern PL that is disposed so as to face the front surface of the projection screen SC. The image pickup apparatus 1 is configured as a so-called digital camera using an image pickup device in which a large number of semiconductor light receiving cells (pixels) are arranged in an XY matrix, such as a CCD image pickup device. The received light amount is output as light intensity data in units of pixels. An elbow point detection device 2 and an optical axis variable device 3 are connected to the imaging device 1. The elbow point detection device 2 detects an elbow point based on the imaging output of the imaging device 1. The optical axis variable device 3 is attached to the headlamp HL only when the optical axis is adjusted, and an optical axis drive for operating a part of the headlamp HL to move the optical axis of the headlamp HL up and down, left and right The optical axis variable device 3 is configured to control the optical axis drive unit 31.

  As the headlamp HL and the optical axis drive unit 31, those proposed so far can be used as they are, so detailed description thereof will be omitted here, but in this embodiment, the headlamp is shown in FIG. As shown in the schematic view seen from the side, the headlamp HL is moved into the lamp housing 41 by rotating the upper and lower aiming bolts 42 and the left and right aiming bolts 43 arranged on the rear surface of the lamp housing 41. The angle of the disposed reflector 44 can be adjusted in the vertical and horizontal directions, and by adjusting the angle, the optical axis of the headlamp HL can be adjusted in the vertical and horizontal directions. The optical axis drive unit 31 can be attached to and detached from the headlamp HL, can be coupled to the upper and lower aiming bolts 42 and the left and right aiming bolts 43, and is independently rotated by an actuator not shown in the drawing. Drivers 32 and 33 are provided. The adjustment drivers 32 and 33 are rotationally controlled by the optical axis variable device 3 to rotate the aiming bolts 42 and 43 to control the optical axis of the headlamp HL as described above. The optical axis variable device 3 recognizes the elbow point EP detected by the elbow point detection device 2, and feedback-controls the optical axis drive unit 31 so that the elbow point EP is located within a predetermined area of the projection screen SC. The optical axis of the lamp HL can be adjusted.

  The elbow point detection device 2 will be described. FIG. 4 is a block diagram of an optical axis adjustment device OCD including the elbow point detection device 2. The elbow point detection device 2 captures light intensity data in units of pixels from the light distribution pattern of the low beam light distribution imaged by the image sensor 11 of the image capture device 1, and detects fine detection errors and noise at each pixel in the captured light intensity data. In order to improve the blur of the edge generated at the boundary between the high light intensity region and the low light intensity region in the light intensity data output from the filter processing unit 21 for removal and the light intensity data to be clear An edge processing unit 22 that performs a process for increasing the difference in luminous intensity data between the two regions, that is, a contrast, and an elbow point calculating unit 23 that calculates an elbow point based on the luminous intensity data that has been increased in contrast by the edge process. The Here, the filter processing unit 21, the edge processing unit 22, and the elbow point calculation unit 23 are not necessarily configured in hardware, and light intensity data input from the imaging apparatus 1 is signaled as can be understood from the description to be described later. Since it only needs to have a function for processing, it can be realized by a software configuration in a microprocessor, for example.

  The elbow point detection process in the elbow point detection unit 2 will be described. FIG. 5 is a diagram of an imaging screen of the imaging device 11 for schematically showing light intensity data of a light distribution pattern imaged by the imaging device 1. A large number of pixels constituting the image sensor 11 output luminous intensity data corresponding to the brightness (luminous intensity) of the light distribution pattern. The filter processing unit 21 extracts light intensity data along the Y direction of the image sensor 11. For example, the luminous intensity data D1 of the pixels arranged in the Y direction along the line X1 in FIG. 5 is as shown in FIG. The luminous intensity data of the area illuminated by the light distribution pattern PL is a relatively high luminous intensity, and the luminous intensity data of the area other than the luminous intensity distribution pattern PL is a low luminous intensity. These luminous intensity data include minute detection errors due to the difference in light receiving sensitivity of each pixel of the image sensor 11 and minute noise due to abnormal reflection on the headlamp HL, the projection screen SC, etc., and therefore the luminous intensity along X1. The data contains minute errors. The filter processing unit 21 performs a moving average process on the light intensity data in units of pixels along the Y direction, and replaces the light intensity data of each pixel with the value obtained by the moving average process. As a result, the luminous intensity data along X1 becomes luminous intensity data D2 in which fine detection errors and noise are reduced or eliminated as shown in FIG. 6B. The filter processing unit 21 performs similar processing while moving in the X direction at least pixels in all regions where the light distribution pattern PL exists, or at least pixels in the central region of the light distribution pattern PL including the elbow point EP. Execute.

  Next, the edge processing unit 22 performs a process of converting the filtered luminous intensity data D2 into digital data. In this embodiment, the light intensity data D2 is binarized using a predetermined threshold value TH1. As the threshold value TH1, an intermediate value between the minimum luminous intensity value and the maximum luminous intensity value of the luminous intensity data D2 filtered as shown in FIG. 6B is used. As a result, as shown in FIG. 6C, the light intensity lower than the threshold value TH1 becomes the “0” value, and the high light intensity becomes the light intensity data D3 expressed by the “1” value. That is, in the luminous intensity data D3, the “1” value region is the region of the light distribution pattern PL, the “0” value region is a region other than the light distribution pattern PL, and both “0” and “1” are present. The value boundary is the Y coordinate boundary position DY as the boundary of the light distribution pattern PL. Note that the brightness data D2 to be edge-processed is smoothed by the filter processing unit 21, so that the “0” value and the “1” value are unstable before and after the threshold value TH1. Therefore, the boundary position DY can be clearly detected.

  Accordingly, the elbow point calculation unit 23 calculates a plurality of pixels (pixel columns) arranged along the Y direction with respect to all the pixels or the pixels targeted for the central region of the light distribution pattern as described above. The brightness data D3 subjected to the edge processing is read, the boundary position DY between the “0” value and the “1” value in the Y direction is recognized, and this boundary position DY is recorded. At this time, the first pixel column is performed for the pixel at the X1 position that intersects the oncoming vehicle side horizontal cut line CLH as shown in FIG. Next, the luminance data D3 in the Y direction is read in the same manner for the pixel column adjacent in the X direction toward the lane side, and in the pixel column at the X2 position adjacent to the left side in FIG. 5, the boundary is recognized, and the boundary position DY is determined. Record. By repeating this operation up to the X3 position in units of one pixel column along the X direction, or the Xn position that has reached the required position of the host vehicle lane-side oblique cut line CLS, the X coordinate as shown in FIG. A change in the boundary position DY with respect to the change can be calculated.

Further, the elbow point calculation unit 23 detects an elbow point EP from the calculated change in the boundary position DY. The change in the calculated boundary position DY does not change substantially until it reaches a certain X coordinate, here the position of Xm, or the change is slight, but when the X coordinate is reached, the pixel row is the vehicle side oblique cut line CLS. Since the crossing occurs, the subsequent boundary position DY gradually increases. At this time, as shown in FIG. 7B in which a part of FIG. 7A is enlarged, the elbow point calculation unit 23 determines the difference between the calculated boundary position DY and the boundary position DY adjacent in the X direction. And the difference is compared with a preset determination threshold value Δy. When this difference is smaller than the determination threshold value Δy, it is determined that the elbow point EP has not been reached. When the difference exceeds the determination threshold value Δy, the X position corresponding to the immediately preceding boundary position DY, here Xm, is determined as the elbow point EP. That is, it means that the change amount of the boundary position DY becomes remarkable at the coordinate Xm, and the boundary position until reaching the coordinate Xm forms the oncoming vehicle side horizontal cut line CLH, and reaches the coordinate Xm. The boundary position DY after having constituted the own vehicle side diagonal cut line CLS. Therefore, the elbow point EP is a coordinate position (Xm, Ym) represented by the X coordinate value Xm at this time and the Y coordinate value Ym corresponding to the boundary position DY in the pixel row at the X coordinate.

  The elbow point EP thus detected by the calculation at the elbow point calculation unit 23 is input to the optical axis variable device 3 as described above, and the optical axis variable device 3 recognizes the coordinates of the detected elbow point EP. Then, the actuator of the optical axis driving unit 31 is feedback-controlled. As described above, the optical axis driving unit 31 controls the vertical aiming bolt 42 and the left and right aiming bolt 43 of the headlamp HL by the actuator, and tilts the reflector 44 in the lamp housing 41 up and down and left and right. The optical axis is adjusted to change vertically and horizontally so that the elbow point EP is positioned within a predetermined region of the projection screen SC, thereby adjusting the optical axis of the headlamp HL.

  As described above, in the elbow point detection device 2 according to the embodiment, the light intensity data of the light distribution pattern PL imaged by the imaging device 1 is subjected to the moving average process in the filter processing unit 21, thereby reducing noise by reducing the change in the light intensity data Etc. can be removed. Further, since the brightness data is binarized in the edge processing unit 22 to increase the contrast, the light / dark boundary is not blurred by noise or the like, and the light / dark boundary, that is, the boundary of the light distribution pattern PL is clearly defined. It becomes possible to make it. Accordingly, the elbow point calculation unit 23 can detect a coordinate point that changes from the oncoming vehicle side horizontal cut line CLH to the host vehicle side oblique cut line CLS from the coordinate movement locus indicating the boundary, that is, the elbow point EP. Therefore, when detecting the elbow point EP, the tilt angle of the oblique cut line as in Patent Document 1 is not required as data, and the operation at the time of detection is simplified and the elbow point can be detected quickly. Is possible. Moreover, there is no case where an elbow point is erroneously detected by inputting an incorrect inclination angle. Furthermore, even when there is an error between the designed tilt angle set for the headlamp and the actual tilt angle, the elbow point can be detected accurately. Thereby, an easy and quick optical axis adjustment is realizable.

  In the embodiment, an example of detecting the elbow point of the low beam light distribution pattern configured by the oncoming vehicle side horizontal cut line and the own vehicle side oblique cut line is shown, but the low beam light distribution pattern having the horizontal cut line on the own vehicle side, That is, the elbow point can be detected in the same manner as in the embodiment with respect to the light distribution pattern having the horizontal cut line in the left region of FIG.

  In the embodiment, the filter processing unit 21 obtains a moving average of the luminous intensity data in the Y direction. However, the filter processing unit 21 is not limited to this configuration as long as it has a function of filtering a minute change in the luminous intensity data. Absent. For example, you may comprise as a frequency filter circuit for interrupting | blocking high frequency components, such as a noise, with respect to the imaging signal output from the imaging device 1, ie, the luminous intensity data when the Y direction is made into a time axis. Or when this kind of filter circuit is provided in the imaging device 1, you may comprise this filter circuit as a filter process part in this invention.

  In the embodiment, the edge processing unit 22 binarizes the light intensity data using an intermediate value between the maximum light intensity value and the minimum light intensity value as a threshold value. For example, as shown in FIG. A value about 20 to 30% of the difference in the minimum luminous intensity value, a value smaller than this, or a slightly larger value is set as the threshold value TH2, and binarization is performed using this threshold value TH2 as shown in FIG. You may make it obtain the luminous intensity data D4 like d). When the slope of the light intensity change at the cut line of the light distribution pattern is large, it is better to recognize the place where the light intensity rises from the low light intensity region to the high light intensity region as the cut line in this way. This is because of the high consistency.

  The imaging apparatus according to the present invention may be any device that can detect the light intensity distribution of the light distribution pattern projected on the projection screen. For example, the light intensity of the light distribution pattern is obtained by scanning the CCD line sensor extended in the Y direction in the X direction. Imaging means for detecting the distribution may be used. Alternatively, instead of projecting the light distribution pattern on the projection screen, the light intensity distribution may be detected by directly receiving the light emitted from the headlamp.

  In the embodiment, the elbow point is detected and the optical axis is adjusted while the headlamp is assembled to the vehicle (automobile). However, when only the headlamp before being assembled to the vehicle is assembled, the headlamp is used as a reference base. In this state, the elbow point may be detected and the optical axis may be adjusted. In this case as well, the present invention can be applied.

  The present invention is not limited to the light distribution pattern of an automobile headlamp as long as it is a detection method and detection device for detecting elbow points in a light distribution pattern of a vehicle headlamp having a horizontal cut line and an oblique cut line. It is possible to adopt.

DESCRIPTION OF SYMBOLS 1 Imaging device 2 Elbow point detection device 3 Optical axis variable device 11 Imaging element 21 Filter processing part 22 Edge processing part 23 Elbow point calculation part 31 Optical axis drive part HL Headlamp SC Projection screen PL Light distribution pattern CLH Oncoming vehicle side horizontal cut Line CLS Own lane side diagonal cut line EP Elbow point OCD Headlamp optical axis adjustment device

Claims (5)

  Elbow inspection that captures the light distribution pattern of the light emitted from the vehicle headlamp and acquires luminous intensity data, and detects the elbow point where the horizontal cut line and the oblique cut line of the light distribution pattern intersect from the acquired luminous intensity data A method of sequentially detecting a light intensity distribution in a vertical direction of a light distribution pattern as the light intensity data along a horizontal direction of the light distribution pattern, and a filter for removing minute fluctuations and noise in the light intensity distribution Processing, performing edge processing to increase the contrast at the boundary between the low light intensity region and the high light intensity region of the filtered light intensity data, and detecting the boundary based on the edge processed light intensity data The vertical position of the detected boundary is calculated along the horizontal direction, and the previous position is calculated based on the vertical position change of the boundary. Elbow point detecting method of the light distribution pattern, which comprises the step of detecting the elbow point.   2. The filter process according to claim 1, wherein the filtering process is a process of moving and averaging the luminous intensity data along a vertical direction, and the edge process is a process of binarizing the luminous intensity data with a predetermined threshold value. Elbow point detection method for light distribution pattern.     Imaging means for capturing a light distribution pattern of light emitted from a vehicle headlamp and acquiring light intensity data obtained by sequentially detecting at least a vertical light intensity distribution of the light distribution pattern along the horizontal direction of the light distribution pattern; An elbow point detection device that detects an elbow point where a horizontal cut line and an oblique cut line of the light distribution pattern intersect is obtained from the acquired light intensity data, and the elbow point detection device removes minute fluctuations and noise in the light intensity distribution. A filter processing unit for performing a filtering process, an edge processing unit for performing a process for increasing a contrast at a boundary between a low light intensity region and a high light intensity region of the filtered light intensity data, and the light intensity data having the increased contrast Based on this, the boundary is detected and the vertical position of the detected boundary is calculated along the horizontal direction. Elbow point detecting device of the light distribution pattern, characterized in that it comprises a elbow point calculation unit that detects the elbow point on the basis of the positional change in the vertical direction of the field.   The imaging means includes an imaging element in which a large number of light receiving cells are arranged in an XY matrix as imaging pixels, and the elbow point detection device obtains light intensity data of pixel columns arranged in the Y direction while sequentially moving in the X direction, The filter processing unit and the edge processing unit perform processing in the Y direction light intensity distribution by the filter processing unit and the edge processing unit, and the elbow point calculation unit calculates the boundary position in the Y direction and the boundary position in the Y direction. The elbow of the light distribution pattern according to claim 3, wherein the Y direction position and the X direction position of the elbow point are detected on the basis of a change in the Y direction of the boundary position. Point detector. The elbow point detecting device according to claim 3 or 4 is integrally assembled with an optical axis adjusting device for adjusting an optical axis of a headlamp of a vehicle, and the elbow point detecting device is based on the elbow point detected by the elbow point detecting device. An elbow point detection device for a light distribution pattern, wherein the optical axis adjustment is performed by an optical axis adjustment device.

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