JP5042581B2 - Detection method of light distribution pattern center - Google Patents

Description

  The present invention relates to a method for detecting the center of a light distribution pattern required for adjusting the optical axis of a vehicle headlamp.

  As a headlight of an automobile, there is a low beam lamp having a required light distribution pattern in which an optical axis is directed downward so as not to dazzle an oncoming vehicle. When adjusting the optical axis so that the optical axis of the low beam lamp is directed in a predetermined direction, it is necessary to detect the center of the light distribution pattern of the light irradiated by the low beam lamp. In other words, the low beam pattern in left-hand traffic like Japan has a horizontal cut line in the right area of the light distribution pattern, and a cut line inclined in the upper left direction in the left area. The intersection with the cut line is called the elbow point and is the center of the light distribution pattern. In the optical axis adjustment of the low beam lamp, the optical axis adjustment is performed so that the elbow point is oriented within a predetermined range. Note that the cut line in the light distribution pattern is generally defined as a line connecting points on the light distribution pattern where the gradient of light intensity is maximum.

In order to detect the elbow point when adjusting the optical axis, the light distribution pattern of the irradiated light is detected by actually turning on the low beam lamp, and the horizontal cut line and the oblique cut line of the detected light distribution pattern are detected. Then, an intersection point between the horizontal cut line and the oblique cut line is obtained, and the intersection point is recognized as an elbow point. As a technique for recognizing such an elbow point, for example, the technique of Patent Document 1 has been proposed. Patent Document 1 is a technique for receiving a light distribution pattern of a headlamp by a light receiving means and calculating an elbow point based on the received illuminance, and from the illuminance obtained in a partial region including a horizontal cut line. The approximate line on the coordinate axis of the horizontal cut line is calculated, and the approximate line on the coordinate axis of the oblique cut line is calculated from the illuminance obtained in the partial area including the oblique cut line. This is a technique for detecting an intersection as an elbow point. Accordingly, it is possible to detect an elbow point in a headlamp composed of a plurality of light source units, and it is possible to test the headlamp.
JP 2000-146761 A

  In the technique of Patent Document 1, in the calculation for obtaining each approximate line of the horizontal cut line and the oblique cut line, the calculation is complicated because the calculation is performed based on the illuminance at a plurality of locations in the area including each cut line. In addition, the number of processes for performing calculations is large, and the computer software becomes complicated. In particular, when the inclination angle of the oblique cut line differs depending on the type of headlamp, or when the illuminance distribution in the light distribution pattern is different, the calculation suitable for each is taken into account. The software of the formula must be designed, and the software becomes complicated and the design of the software becomes complicated. In addition, since the number of calculation processes is large, the calculation time becomes long, and it takes time to detect the elbow point. Furthermore, since the approximate lines of the horizontal cut line and the oblique cut line are approximate values, the detection accuracy of the elbow point that is the intersection of these cut lines must be lowered. In particular, in an actual lamp light distribution pattern, a wavy pattern (hereinafter referred to as a wavy portion) often occurs in a cut line due to a manufacturing error in a component such as a reflector or a lens constituting the lamp. The wavy portion causes an error in the approximate line of the cut line, and there is a problem that the elbow point detection error becomes remarkable.

  An object of the present invention is to provide a light distribution pattern center detection method capable of detecting a light distribution pattern center (elbow point) simply and quickly with high accuracy.

The present invention detects the center of a light distribution pattern having a horizontal cut line that extends substantially horizontally through the center of the light distribution pattern and an oblique cut line that extends through the center in a required angular direction with respect to the horizontal direction. A first light-receiving region and a second light-receiving region, which are opposed to each other in the vertical direction across an upper and lower intermediate region having a vertical width dimension similar to the height dimension of the wavy portion due to the cut blur generated in the horizontal cut line . Using a light receiving means having a light receiving area, the light distribution pattern is received while changing the position of the light receiving means in the vertical direction, and the light receiving ratio of the amount of received light detected in the first light receiving area and the second light receiving area is obtained. The method includes a step of detecting a vertical position of the horizontal cut line based on the ratio. In particular, the middle point in the vertical direction of the vertical middle region when the extreme value of the light reception ratio is obtained is detected as the vertical position of the horizontal cut line.

According to the present invention, the light receiving amounts of the first light receiving region and the second light receiving region arranged opposite to each other with the upper and lower intermediate regions interposed therebetween are detected, and the vertical position of the horizontal cut line is detected based on these light receiving ratios. As a result, the horizontal cut line can be detected with high accuracy even when the horizontal cut line has a wavy portion due to cut blur. Theoretically, when the vertical width of the upper and lower middle region matches the height of the wavy portion caused by the cut blur of the horizontal cut line, the detected peak position of the light reception ratio is detected as it is as the position of the horizontal cut line. it can. If they do not match, the intermediate position of the region where the peak of the light reception ratio can be detected as the position of the horizontal cut line. Further, since the horizontal cut line is simply detected based on the change in the light receiving ratio of the light receiving amount of the first light receiving region and the second light receiving region, the processing for calculating the light receiving amount can be simplified, and the detection device can be simplified. The detection process can be speeded up.

  In the present invention, the upper and lower intermediate regions are configured as a third light receiving region, and the sum of the respective light receiving amounts of the first light receiving region and the third light receiving region and the sum of the respective light receiving amounts of the second light receiving region and the third light receiving region. The light reception ratio may be obtained, and the vertical middle point of the extreme value of the light reception ratio may be detected as the vertical position of the horizontal rat line. Even if the difference in the height of the wavy part generated in the horizontal cut line is larger than the vertical width of the upper and lower intermediate areas, fluctuation of the light reception ratio due to the change in the position of the light receiving means is suppressed, and the influence of the wavy part is reduced. Detection with higher accuracy.

  In the present invention, the light receiving means is constituted by a two-dimensional image pickup device, a large number of light receiving cells constituting the image pickup device are divided into respective light receiving regions and upper and lower intermediate regions, and the received light amounts of the light receiving cells belonging to each region are added. You may make it detect the light reception amount of each said light reception area | region. A means for changing the position of the light receiving means becomes unnecessary, and the detection apparatus can be simplified and the cost can be reduced.

  Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view showing a schematic configuration of a headlamp HL for detecting an elbow point by the detection method of the present invention, here, a right headlamp RHL disposed on the front right side of an automobile. A high beam lamp HBL and a low beam lamp LBL are configured in a lamp chamber 13 including a lamp body 11 and a transparent cover 12 attached to the front opening of the lamp body 11. Here, the high beam lamp HBL is composed of a single projector type lamp using a discharge bulb as a light source, and a projector type lamp using this discharge bulb as a light source is already widely known. The low beam lamp LBL is configured as a multi-light source lamp in which a plurality of light source units LU1 to LU4 each having a semiconductor light emitting element as a light source are arranged. The four light source units LU1 to LU4 are composed of three projector type light source units LU1 to LU3 and one diffusion type light source unit LU4. Are arranged side by side in the horizontal direction, and a diffusion type light source unit LU4 is arranged at the lower stage.

  In the low beam lamp LBL, a detailed description of each of the light source units LU1 to LU4 is omitted, but as shown in FIG. 2, the low beam pattern LBP is formed by superimposing the light distribution patterns P1 to P4 of the light source units LU1 to LU4. It is formed. The low beam pattern LBP has a horizontal cut line HC extending in the horizontal direction and an oblique cut line DC that intersects the horizontal cut line HC at a predetermined angle, and serves as a reference for a light distribution pattern. In the vicinity including the optical axis point HV where the line H and the vertical reference line V intersect, the horizontal cut line HC and the oblique cut line DC intersect, and this intersection becomes the center of the light distribution pattern and becomes a so-called elbow point EP.

  In order to detect the elbow point EP of the light distribution pattern of the low beam lamp LBL, an elbow point detection device 100 is provided. As shown in the conceptual configuration of FIG. 3, the elbow point detection device 100 is disposed so as to face the front of the headlamp HL when the car CAR equipped with the headlamp HL for detecting the elbow point is stopped at a predetermined position. In addition, the image pickup apparatus 110 is provided that can move in a horizontal horizontal direction and a vertical vertical direction with respect to the automobile. Here, as a mechanism for moving the imaging device 110 up and down, left and right, here, the H bar 101 extended in the horizontal left and right direction and supported at both ends by the support, and the H bar 101 can be moved in the left and right direction. A left and right moving body 103, a V bar 102 having an upper end connected to the left and right moving body 103 and extending vertically and a vertical moving body 104 movable on the V bar 103 in the vertical direction. The imaging device 110 is mounted on the vertically moving body 104. The elbow point detection device 100 is also provided with a screen SC for projecting the light of the headlamp HL.

  The imaging device 110 receives the light emitted from the headlamp HL and visualizes the light distribution pattern, and imaging for imaging the light distribution pattern visualized on the light receiving plate 111. A camera 112 is provided. Although not shown in the drawing, the imaging camera 112 includes an imaging element made of a semiconductor photoelectric conversion element such as a CCD that outputs a light reception signal based on the captured light distribution pattern. As shown in the conceptual configuration in FIG. 4A, the image sensor 113 is a two-dimensional CCD having a large number of cells (light receiving elements) 114 arranged in a matrix in the left and right directions and the vertical direction on an imaging surface (light receiving surface) 113a. Each cell 114 is configured by an image sensor, and outputs an electrical signal corresponding to the brightness of the captured light distribution pattern as a light reception signal. The light reception signal output from the image sensor 113 is output to the signal processing unit 120 shown in FIG. 3, and the signal processing unit 120 performs signal processing with a required algorithm based on the input light reception signal, and the elbow point The calculation for calculating the position of is performed.

  Here, in the imaging device 113, as shown in FIG. 4B, the center point (upper and lower left and right center points) C of the imaging surface 113a of the imaging device 113 is included for many cells 114 arranged in a matrix. An upper and lower intermediate region A3 having a required width dimension in the vertical direction is defined, and an upper first light receiving region A1 and a lower second light receiving region A2 that are symmetrically arranged vertically with respect to the upper and lower intermediate region A3 are defined. . In the first embodiment, the first light receiving area A1 and the second light receiving area A2 are formed over the entire width in the left-right direction of the imaging surface of the image sensor 113, and the vertical direction of the first light receiving area A1 and the second light receiving area A2. Are set equal to each other, the number of cells in the first light receiving region A1 and the second light receiving region A2 is the same, in other words, the respective light receiving areas of the first light receiving region A1 and the second light receiving region A2 are equalized. ing. In addition, the upper and lower intermediate area A3 is defined as a third light receiving area in the second embodiment as will be described later. The vertical width of the upper and lower intermediate area A3 is a low beam as can be seen from the description to be described later. The height is set to be approximately the same as the height of the wavy portion in the vertical direction due to the blurring generated in the horizontal cut line HC in the light distribution pattern LBP.

  As shown in FIG. 4C, in the image sensor 113, the left fourth light receiving area A4 and the right fifth light receiving area A4 arranged in parallel in contact with the left and right directions including the center point C of the imaging surface 113a. A light receiving area A5 is defined. The fourth light receiving region A4 and the fifth light receiving region A5 are formed over the entire length in the vertical direction of the imaging element 113, and the width dimensions in the horizontal direction of the fourth light receiving region A4 and the fifth light receiving region A5 are set equal. Therefore, the number of cells in the fourth light receiving region A4 and the fifth light receiving region A5 is the same, in other words, the light receiving areas of the fourth light receiving region A4 and the fifth light receiving region A5 are equal.

  The signal processing unit 120 calculates the left-right position (coordinates) and the vertical position (coordinates) of the elbow point EP based on the light reception signal output from the image sensor 113. In order to perform this calculation, the signal processing unit 120 calculates the amount of received light for each region based on the received light signal from each cell of each of the first to fifth regions of the image sensor, and the obtained received light amount. Based on the above, it is possible to perform a required calculation. Here, since the image sensor 113 is composed of a CCD element, the charge as a light reception signal obtained by receiving light in each of the cells 114 constituting the image sensor 113 is sequentially transferred to obtain the charge of each cell. It is assumed that a gradation signal is obtained by quantizing the value of each read-out charge and the read-out charge as a 1-bit to several-bit digital signal. In this case, the number of bits can be appropriately set according to the processing capability of the signal processing unit 120 and the required accuracy. In particular, if the gradation signal is 1 to several bits, the signal in the signal processing unit 120 The processing speed can be improved, and conversely, the detection accuracy can be increased by using a multi-gradation signal having a plurality of bits. This detection is performed for the cells belonging to the first to fifth regions A1 to A5, and the received light amount of each cell, that is, the multi-tone signal is added to obtain the received light amount of each region A1 to A5.

A method for detecting the elbow point EP in the low beam light distribution pattern LBP of the headlamp HL using the elbow point detection apparatus 100 described above will be described. First, as shown in FIG. 3, the automobile CAR is stopped at a position facing the imaging device 110. Next, the headlamp HL is turned on, and the light emitted from the headlamp HL is imaged by the imaging device 110. In the imaging device 110, the light distribution pattern of the headlamp is visualized on the light receiving plate 111, and this is captured by the imaging camera 112. The image sensor 113 in the imaging camera 112 outputs the light reception signal received by each cell 114 for each cell, and the controller 120, based on the light reception signal of each cell, each region, here the first light reception region A1 and the second light reception region. Each received light amount of A2 is calculated. In this calculation, the gradation signal as each received light signal of all the cells constituting the first light receiving region A1, that is, the first received light amount P1 obtained by adding the received light amount, and all the second light receiving regions A2 are similarly configured. The second received light amount P2 obtained by adding all the received light amounts obtained from the respective received light signals of the cell is calculated, and then the value obtained by dividing the second received light amount P2 by the first received light amount P1 is set to the vertical EP (elbow). Point) Value VEPx. That is, the following equation is obtained.
VEPx (upper and lower EP values) = P2 ÷ P1

  After obtaining the vertical EP value VEPx at the predetermined height position of the imaging device 110 in this way, the vertical moving body 104 is then driven along the V bar 102 to turn the imaging device 110 upward or downward. The image is moved by a small distance toward the direction, the low beam distribution pattern LBP is similarly imaged by the imaging device 110 at the movement position, and the controller 120 performs the calculation based on the received light signal obtained from the imaging element 113. An upper and lower EP value VEPx at the height position is calculated. This process is performed for a number of positions while moving the imaging device 110 in the vertical direction. For the obtained vertical EP value VEPx, as shown in FIG. 5A, a graph is drawn with the horizontal axis indicating the vertical position Vx of the imaging device 110 and the vertical axis indicating the vertical EP value VEPx. Here, the vertical position of the imaging device 110 is the vertical position of the center point C of the imaging surface of the imaging element 113.

  From FIG. 5A, the vertical EP value VEPx changes with the vertical position change of the image sensor 113. Therefore, when the maximum value and the vertical intermediate position PVEP are obtained, this position VEP becomes the elbow point EP. Is the vertical position of the horizontal cut line HC. That is, FIGS. 5B to 5E are schematic diagrams for explaining this, and FIGS. 5B to 5E show the states at the abscissa position in FIG. 5A. When the horizontal cut line HC is above the first light receiving area A1 of the image sensor 113 as shown in FIG. 5B, almost all of the second light receiving area A2 and the first light receiving area A1 are below the horizontal cut line HC. The upper and lower EP values VEPx are low because they are in the region LBP of the low beam distribution pattern on the side. As shown in (c), when the image sensor 113 is moved upward and the horizontal cut line HC is in the vicinity of the lower part of the first light receiving area A1, the amount of light received in the first light receiving area A1 is reduced, so that the vertical EP value VEPx increases. Begin to. As shown in (d), when the image sensor 113 is moved further upward and the horizontal cut line HC is in the upper and lower intermediate region A3, the amount of light received by the first light receiving region A1 is almost zero, and the second light receiving region A2 Since the amount of received light is the maximum, the upper and lower EP values VEPx hold the maximum value. As shown in (e), when the horizontal cut line HC enters the second light receiving area A2, the amount of light received in the second light receiving area A2 decreases, and therefore the upper and lower EP values VEPx begin to decrease. From this, the maximum vertical EP value VEPx is between the position V1 where the horizontal cut line HC exceeds the lower edge of the first light receiving area A1 and the position V2 where the upper edge of the second light receiving area A2 exceeds. The intermediate position between these positions V1 and V2 is detected as the vertical position of the horizontal cut line HC. In FIGS. 5B to 5E, although not illustrated in the area above the horizontal cut line HC, in practice, some light is present and the first light receiving area A1 is also finite. Since there is a received light amount, the upper and lower EP values VEPx do not become infinite values.

  At this time, in the horizontal cut line HC, a vertical wavy portion HW is generated due to cut blur due to factors such as a reflector and a lens constituting the headlamp HL. If the upper and lower intermediate region A3 does not exist between the first light receiving region A1 and the second light receiving region A2, a part of the upper wave portion of the wavy portion HW of the horizontal cut line HC is the first light receiving portion. There is a situation in which light is received in the area A1 and a part of the lower wave portion is not received in the second light receiving area A2, thereby causing a slight fluctuation in the upper and lower EP values VEPx, and the accuracy in detecting the position of the horizontal cut line HC is lowered. There is a fear. In the first embodiment, the upper and lower intermediate areas A3 having dimensions approximately the same as the height of the corrugated part HW are present, so that the upper and lower wave parts of the corrugated part HW are received by the upper and lower intermediate areas A3, or Even if the light is not received, the light reception of the first light receiving region A1 and the second light receiving region A2 is not affected, so that the influence of the wavy portion HW can be eliminated, and the position detection accuracy of the horizontal cut line HC is improved. Can do.

Next, after fixing the vertical position of the imaging device 110 so that the center point C of the imaging device 110 is positioned on the detected horizontal cut line HC, the imaging device 110 captures the low beam light distribution pattern LBP, After that, the controller 120 outputs a light reception signal received by each cell of the fourth light reception region A4 and the fifth light reception region A5 for each cell, and performs a required calculation based on the light reception signal of each cell. This calculation is based on the fourth light reception amount P4 obtained by adding the light reception amounts obtained from the light reception signals of all the cells constituting the fourth light reception region A4 and the light reception signals of all the cells constituting the fifth light reception region A5. A division with the fifth received light amount P5 obtained by adding all the received light amounts is performed, and the obtained value is set as a left and right EP value HEPx. That is, the following equation is obtained.
HEPx (left and right EP value) = P4 ÷ P5

  After obtaining the left and right EP values HEPx at the predetermined left and right positions of the imaging device 110 in this way, the left and right moving body 103 integrated with the V bar 102 is then driven along the H bar 101 to move the imaging device 110 to the right. The image pickup device 110 picks up the low beam light distribution pattern LBP by moving a small distance toward the left direction or toward the left direction, performs the calculation in the controller 120 based on the obtained light reception signal, and at the moving position The left and right EP values HEPx are calculated. This process is performed for a number of positions while moving the imaging device 110 in the left-right direction. For the obtained left and right EP value HEPx, as shown in FIG. 6A, a graph is drawn with the horizontal axis indicating the position Hx in the horizontal direction of the imaging apparatus and the vertical axis indicating the left and right EP value HEPx. Here, the horizontal position of the imaging device 110 is the horizontal position of the center point C of the imaging element 113.

  From FIG. 6A, the left and right EP values HEPx change in accordance with the change in position of the image sensor 113 in the left and right direction. Therefore, when the position of the image sensor 113 is changed from right to left, the maximum position H1 is cut obliquely. A position where the line DC intersects the horizontal cut line HC, that is, a position in the left-right direction of the elbow point EP. FIGS. 6B to 6D are schematic diagrams for explaining this, but the light distribution pattern has the highest luminous intensity in the vicinity of the elbow point EP where the horizontal cut line HC and the oblique cut line DC intersect, and the elbow point. The light intensity gradually decreases downward and leftward from the EP, and a part of the light intensity contour line is added to the figure. In addition, although no stippling is shown in the region above the horizontal cut line HC and the oblique cut line DC, there is actually some light. When the elbow point EP is on the left side of the fourth light receiving region A4 of the image sensor 113 as shown in (b), the received light amount of the fifth light receiving region A4 and the received light amount of the fourth light receiving region A4 are substantially equal. The EP value HEPx is almost “1”. When the image sensor 113 moves to the left as shown in (c) and the elbow point EP enters the fourth light receiving area A4, the amount of light received in the fourth light receiving area A4 increases, so that the left and right EP values HEPx gradually increase. To increase. Further, as shown in (d), the image sensor 113 moves to the left, and the elbow point EP is at the boundary position between the fourth light receiving area A4 and the fifth light receiving area A5, that is, the center of the image sensor 113 coincides with the elbow point EP. At this time, since the fourth light receiving area A4 enters the area of the maximum luminous intensity of the light distribution pattern, the left and right EP values HEPx are maximized. When moving further to the left, although not shown, the amount of light received in the fourth light receiving region A4 is saturated and the amount of light received in the fifth light receiving region A5 further increases, so the left and right EP value HEPx gradually decreases. At this time, although there are slight fluctuations in the light receiving amounts of both the light receiving areas A4 and A5 due to the wavy portion, the fluctuations in both the light receiving areas A4 and A5 are almost the same, so they are canceled out and almost negligible. When the fifth light receiving area A5 also enters the lower side of the oblique cut line DC as shown in (e), the received light amounts of the fourth light receiving area A4 and the fifth light receiving area A5 are substantially equal, and the right and left EP The value HEPx value is almost “1”. Therefore, the center position C of the image sensor 113 at the position H1 at which the light reception ratio is the maximum in the obtained light reception ratio characteristic is detected as the position HEPx in the left-right direction of the elbow point EP.

  As described above, in the first embodiment, the respective light receiving amounts P1 and P2 of the first light receiving region A1 and the second light receiving region A2 that are arranged to face each other with the upper and lower intermediate region A3 interposed therebetween are detected, and based on these light receiving ratios. Since the vertical position of the horizontal cut line HC is detected, the horizontal cut line HC can be detected with high accuracy even when the horizontal cut line HC has wavy portions HW due to cut blurring. Further, the point where the horizontal cut line HC and the oblique cut line DC intersect based on the light receiving ratio of the fourth light receiving region A4 and the fifth light receiving region A5 arranged in parallel in the left-right direction, that is, the elbow point EP is defined as Can be detected. As a result, the elbow point EP can be detected with high accuracy even when a wavy portion is generated in the cut line. As described above, in the first embodiment, since the elbow point is simply detected based on the light reception ratio of each region, the calculation processing in the signal processing unit 120 can be simplified, the configuration of the elbow point detection device can be simplified, and the detection processing can be simplified. High speed can be realized.

Here, as a modification of the first embodiment, the light receiving amount of the third light receiving region A3 configured by the upper and lower intermediate regions may be added to detect the vertical position of the horizontal cut line HC. In this case, in the signal processing unit 120, a second light receiving amount (P2 + P3) obtained by adding the light receiving amounts P2 and P3 of the second light receiving region A2 and the third light receiving region A3, and the first light receiving region A1 and the third light receiving region. The ratio of the first +3 received light amount (P1 + P3) obtained by adding the received light amounts P1 and P3 of A3 is defined as an upper and lower EP value VEPy.
VEPy (up and down EP value) = (P2 + P3) ÷ (P1 + P3)

  In this modification, the vertical EP value VEPy changes in the same manner as shown in FIG. 5 in accordance with the vertical position change of the image sensor 113. Therefore, the vertical range in which the maximum value can be obtained is obtained. The middle position of the range is the vertical position of the horizontal cut line HC. When the horizontal cut line HC is above the third light receiving area A3 of the image sensor 113, the second light receiving area A2, a part of the first light receiving area A1, and the third light receiving area A3 are below the horizontal cut line HC. Since it is in the region of the light distribution pattern, the first +3 received light amount P1 + P3 is small, the second +3 received light amount P2 + P3 is large, and therefore the upper and lower EP values VEPy are low. On the other hand, when the horizontal cut line HC is below the third light receiving area A3 of the image sensor 113, the first light receiving area A1, a part of the second light receiving area A2, and the third light receiving area A3 are horizontally cut. Since it is in a region other than the light distribution pattern on the upper side of the line, the first +3 received light amount P1 + P3 is small, and the second +3 received light amount P2 + P3 is slightly small, so that the vertical EP value VEPy is low. When the horizontal cut line HC is in the third light receiving area A3 of the image sensor 113, the first light receiving area A1 is in an area other than the light distribution pattern, the second light receiving area A2 is in the area of the light distribution pattern, and the third light receiving area In the area A3, since the lower part is in the area of the light distribution pattern and the upper part is in the area other than the light distribution pattern, the upper and lower EP values VEPy are large values. Then, the center point C of the image sensor 113 at the position where the maximum value among the calculated vertical EP values is obtained is detected as the vertical position of the horizontal cut line HC.

  After detecting the vertical position of the horizontal cut line HC, the horizontal position of the elbow point EP can be detected as in the first embodiment. Also in the case of this modification, the received light amounts of the first light receiving area A1 and the second light receiving area A2 which are arranged vertically opposite to each other with the third light receiving area A3 interposed therebetween are detected, and the horizontal direction is determined based on these light receiving ratios. Since the vertical position of the cut line HC is detected, even when the wavy portion HW due to the cut blur occurs in the horizontal cut line HC, the third light receiving region A3 is used as the numerator and denominator when calculating the light receiving ratio. Since the received light amount of the same received wave portion HW is added, the received light of HW is canceled by the wave portion, and the horizontal cut line HC can be detected with high accuracy. In addition, since the signal processing unit 120 simply detects the horizontal cut line HC based on the ratio of the amount of light received in each region, the calculation process can be simplified, the configuration of the elbow point detection device is simplified, and the detection process is speeded up. The same can be achieved.

  In the first embodiment, a light receiving sensor such as a photodiode may be used as the imaging element as long as the light quantity in each of the first to fifth areas A1 to A5 can be detected. For example, as shown in FIG. 7, each of the plurality of light receiving sensors includes six light receiving sensors S1 to S6 corresponding to the first to fifth light receiving regions A1 to A5, and each of the six light receiving sensors S1 to S6. By selectively adding the received light amounts, the received light amounts of the first to fifth regions A1 to A5 can be obtained. For example, the first light receiving area A1 is the light receiving sensor S1 + S2, and the second light receiving area A2 is the light receiving sensor S3 + S4. Similarly, the fourth light receiving area A4 is the light receiving sensor S1 + S3 + S5, and the fifth light receiving area A5 is the light receiving sensor S2 + S4 + S6. Or although illustration is abbreviate | omitted, what is necessary is just to arrange | position a some light reception sensor in each of 1st thru | or 5th area | region A1-A5, and to obtain light reception amount based on the light reception output of each light reception sensor. In this case, it is preferable to dispose a diffusion filter such as a milky white filter on the front surface of the light receiving sensor. By disposing the diffusion filter, an average amount of received light in each region can be obtained.

  In the first embodiment, the first light receiving region A1 and the second light receiving region A2 are formed in the same shape and area, but it is not always necessary to do so. If the light receiving ratio of both light receiving areas A1 and A2 is set to an arbitrary value in advance, the vertical EP value VEPx in the characteristics shown in FIG. Since the value characteristic itself shows a similar tendency, the horizontal cut line HC can be obtained in the same manner as in the first embodiment. Therefore, the first light receiving region A1 and the second light receiving region A2 do not necessarily have to be formed in the same area or symmetrically as in the first embodiment.

  FIG. 8 is a diagram illustrating the image sensor of the second embodiment. In the second embodiment, it is not necessary to move the imaging device 110 up and down, left and right like the elbow point detection device 100 shown in FIG. 3, and the imaging device 110 is fixedly arranged. That is, as shown in FIG. 8, the image sensor 113 is configured to be able to collectively image a relatively wide area of the horizontal cut line HC including the elbow point EP of the low beam light distribution pattern LBP and the oblique cut line DC. Accordingly, when processing the light reception signal output from each cell 114 of the image sensor 113 in the signal processing unit 120, a part of the cell 114 is selected by the soft processing in the signal processing unit 120, and the selected cell is selected. As shown in FIGS. 5 and 6 of the first embodiment, the received light amount corresponding to each of the first to fifth light receiving areas A1 to A5 is obtained.

  For example, in FIG. 8, a cell group C1 included in a predetermined rectangular area is selected from all the cells 114 constituting the image sensor 113, and the cells constituting the cell group C1 are moved upward, middle, By subtracting the respective received light amounts, the total received light amounts of the divided cells can be obtained as the received light amounts P1 to P3 of the first to third light receiving regions A1 to A3 in FIG. . The cell group C2 in FIG. 8 can be selected by changing the cell group selected in the signal processing unit 120, and the received light amount is equivalent to the position change of the light receiving regions A1 to A3 with respect to the low beam light distribution pattern LBP. P1 to P3 can be obtained. In this way, the signal processing unit 120 can obtain the amount of received light in an arbitrary region with respect to the low beam light distribution pattern LBP without moving the image sensor 113, and therefore, the first embodiment is based on the obtained amount of received light. By performing the same calculation as above, the vertical position of the horizontal cut line HC on the image sensor 113 can be detected.

  Similarly, although not shown in the figure, by changing the cell 114 selected in the signal processing unit 120, it is possible to obtain the difference in light reception in the left-right direction as shown in FIG. Can be detected. At this time, it goes without saying that the vertical center of the cell group to be selected is set on the horizontal cut line HC obtained earlier and changed in the left-right direction. In the second embodiment, since the elbow point detection device does not require a moving mechanism, the configuration and control of the device can be simplified. In addition, since calculation can be performed by software processing in the signal processing unit 120, high-speed detection is possible.

  In the first and second embodiments, the signals received by the cells in each region are obtained as multi-gradation digital signals, so that when the signal processing unit 120 is configured by a microcomputer, the light reception ratio and the light reception difference are calculated as they are. This is advantageous for speeding up the processing. In particular, detection with extremely high accuracy is possible by increasing the number of gradations of the digital signal as much as possible. Alternatively, the received light amount received by each cell may be output as an analog amount, and these received analog amounts may be added to obtain the received light amount. In this way, when the received light amount is handled as an analog amount, it is advantageous when each region is constituted by a light receiving sensor.

  The detection method of the present invention can be applied not only to the detection of the center of the light distribution pattern in the multi-light source headlamp as shown in the first embodiment, but also to the conventional single light source headlamp. Needless to say. Further, the present invention is not limited to the case where the light emitted from the headlamp is directly received, but by imaging the light emitted from the headlamp HL projected onto the screen SC as shown in FIG. Similarly, it is possible to detect the center of the light distribution pattern.

1 is an external perspective view of a headlamp that performs detection in Example 1. FIG. It is a figure which shows the low beam pattern of a headlamp. It is a conceptual diagram of an elbow point detection apparatus. It is a conceptual lineblock diagram of an image sensor. It is a figure explaining the method to detect the up-down direction position of a horizontal cut line. It is a figure explaining the method to detect the left-right direction position of an elbow point. It is a conceptual diagram of the modification of an image sensor. FIG. 3 is a conceptual configuration diagram of an image sensor of Example 2.

Explanation of symbols

100 Elbow Point Detection Device 110 Imaging Device 112 Imaging Camera 113 Imaging Device 114 Light-receiving Cell HL Headlamp LBP Low-beam Light Distribution Pattern EP Elbow Point HC Horizontal Cutline DC Oblique Cutline HW, DW Waveforms A1 to A6 Light-receiving Areas P1 to P5 Light-Reception Quantity VEPx, VEPy Top and bottom EP value HEPx Left and right EP value

Claims (4)

A detection method for detecting the center of the light distribution pattern having a horizontal cut line that extends substantially horizontally through the center of the light distribution pattern and an oblique cut line that extends through the center and in a required angle direction with respect to the horizontal direction. A first light receiving region and a second light receiving region which are disposed opposite to each other in the vertical direction with an upper and lower intermediate region having a vertical width dimension comparable to the height dimension of the wavy portion due to the cut blur generated in the horizontal cut line. The light distribution means is used to receive the light distribution pattern while changing the position of the light reception means in the vertical direction, and the light reception ratio of the light reception amounts detected in the first light reception area and the second light reception area is obtained, A method for detecting the center of a light distribution pattern, comprising: detecting a vertical position of the horizontal cut line based on a ratio.   2. The center of the light distribution pattern according to claim 1, wherein a vertical middle point of the vertical middle region when the extreme value of the light reception ratio is obtained is detected as a vertical position of the horizontal cut line. Detection method.   The upper and lower intermediate region is configured as a third light receiving region, and receives the sum of the received light amounts of the first light receiving region and the third light receiving region and the sum of the received light amounts of the second light receiving region and the third light receiving region. 3. The light distribution according to claim 1, wherein a ratio is obtained, and an intermediate point of the upper and lower intermediate regions when the extreme value of the light reception ratio is obtained is detected as a vertical position of the horizontal rat line. Pattern center detection method. The light receiving means is a two-dimensional image pickup device, and a plurality of light receiving cells constituting the image pickup device are divided into the light receiving regions and intermediate regions, and the light receiving amounts of the light receiving cells belonging to the regions are added to each of the light receiving devices. 4. The method for detecting the center of a light distribution pattern according to claim 1, wherein the amount of received light in the region is detected.

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