JP4610186B2 - Method and apparatus for measuring light intensity of headlight tester - Google Patents

Description

  The present invention relates to a light intensity measuring method and apparatus for measuring the light intensity of an automobile headlight tester.

For the light intensity measurement of a conventional headlight tester, a light distribution screen for receiving convergent light from the condenser lens is provided in a housing provided with a condenser lens for converging headlight light on the front surface, There are known ones in which a plurality of photometric sensors are provided on a light distribution screen, or the photometric sensors are movably provided (see Patent Document 1).
Japanese Patent Laid-Open No. 08-338788

  However, in the photometric measurement by the photometric sensor, there is a measurement variation error for each sensor in the case of multiple sensors, and even if it is a single sensor, the photometric sensor itself is an analog and the performance deteriorates due to the analog There was a point.

  Therefore, photometric measurement using an image capturing CCD camera instead of a photometric sensor has been attempted.

  The present invention solves this problem, uses a CCD camera for light intensity measurement, creates a coefficient of light intensity and shutter speed based on a light source of known light intensity, and multiplies the coefficient by a numerical value at the time of measurement to obtain an unknown It is an object of the present invention to provide a headlight tester light intensity measurement method and apparatus for accurately calculating light intensity.

In order to achieve the above object, the first invention relates to a measuring method, and a CCD camera in which a light distribution screen is provided in front of a reference light source having a known luminous intensity and fixed to a predetermined aperture value for light distribution detection toward the light distribution screen. And changing the luminous intensity of the reference light source to a plurality of predetermined luminous intensity values on the luminous screen, and detecting the luminous intensity distribution for each luminous intensity value with the CCD camera, and for each luminous intensity value, the CCD if the camera shutter speed of the variable to a saturated state light too bright expanded across a faster shutter speed of the CCD camera reduces the amount of light, the CCD camera if dark no light saturation previous state The shutter speed is slowed down to increase the amount of light, and the appropriate shutter speed when the CCD camera output at the highest light intensity point is focused on one point is determined. In the corresponding group a proper shutter speed to create the intensity and appropriate shutter speed coefficient advance Re respectively, at the time of measurement, the state of the CCD camera output for the highest light intensity point of the light distribution of the unknown light focused to a point The shutter speed is increased or decreased so that an appropriate shutter speed is obtained when the focal point is focused on a single point, and the optimal shutter speed of the unknown light is multiplied by the luminous intensity / appropriate shutter speed coefficient to obtain the maximum of the unknown light distribution. The light intensity at the light intensity point is calculated. Further, the second invention relates to a measuring apparatus, wherein a condensing lens for converging headlight light is provided on the front surface of a casing movable vertically and horizontally, and light distribution for receiving the converging light from the condensing lens in the casing. the CCD camera fixed to a predetermined aperture value to detect the light distribution on the screen and light distribution screen provided, the CCD camera output for the highest light intensity point of the light distribution at the time of measurement by entering the output from the CCD camera Increase or decrease the shutter speed so that it is in focus at one point, and multiply the appropriate shutter speed when in focus at one point by the luminous intensity / appropriate shutter speed coefficient created based on a reference light source of known luminous intensity. An arithmetic processing unit that calculates the luminous intensity of the highest luminous intensity point of the light distribution is provided, and the arithmetic processing unit includes a first storage unit that stores the luminous intensity and an appropriate shutter speed coefficient, and a maximum luminous intensity point of the luminous intensity distribution at the time of measurement . suitable positive And connecting the second storage unit for storing the value of Yatta speed.

  According to the present invention, a light intensity / appropriate shutter speed coefficient based on a known light intensity light source is preliminarily created using a CCD camera in the photometric measuring device, and the coefficient is multiplied by the shutter speed at the time of measurement. This has the effect of accurately calculating the luminous intensity at the luminous intensity point.

  Originally, the headlight measures luminosity and the angle of deflection of the optical axis in front of 10 meters, and JIS stipulates that the headlight usually faces a light receiving surface with a fixed area 1 meter ahead due to space constraints. I am letting.

  A method for measuring the luminous intensity of a headlight tester that is Embodiment 1 of the present invention will be described with reference to FIGS.

  A measuring apparatus 1 for photometric measurement shown in FIG. 1 projects a condensing lens 2 which is a light receiving surface provided on the front surface of a housing 1a which is a light receiving housing, and light A focused by the condensing lens 2 is projected. A light distribution screen 3, a CCD camera 4 for detecting the light distribution projected on the light distribution screen 3, and an image processing calculation unit 5 that inputs an output from the CCD camera 4 and performs image processing and calculation. Consists of.

  Then, the distance L between the light A and the condenser lens 2 is set to 1 meter, the center position of the light A and the center position of the light distribution screen 3 (intersection of the XY axes) are matched, and light distribution detection is performed. The center point seen by the CCD camera 4 is made to coincide with the intersection of the XY axes.

  In the present invention, since a CCD camera that is not originally a photometric sensor is used instead, a reference light source having a known luminous intensity is selected as a luminous intensity reference, and a characteristic coefficient between luminous intensity and shutter speed is created in advance.

  This reference light source is a kind of headlight of an automobile, and an instruction value from 0 to 1200 hcd (hectocandela) of a photometer provided 10 meters ahead is valued according to a voltage value applied to the filament.

  For example, applied voltage values corresponding to a plurality of predetermined light intensity values, 50, 75, 100, 120, 150, 400, 700, and 1000 hcd are set.

  First, as a first step, the light A is used as the reference light source, and the applied voltage value is varied so that the light intensity of the reference light source of the light distribution on the light distribution screen 3 becomes a plurality of predetermined light intensity values as described above. The CCD camera 4 captures the light distribution for each light intensity value as shown in FIG.

  The CCD camera 4 is fixed at a predetermined aperture value, and the shutter speed remains arbitrary in this first stage.

As a second stage, it is determined from the data whether the analog amount of the CCD camera output at the maximum luminous intensity point P shown in FIG. 3 of the light distribution for each luminous intensity value is in a saturated state or before saturation.

3 shows the light intensity curve of the X-axis of the light distribution in FIG. 2, the vertical axis shows the shutter speed, the upper part has a higher shutter speed, the lower part has a lower speed, and the shutter speed S ₁ is before saturation and S _2. In a saturated state, S indicates an appropriate shutter speed at the maximum luminous intensity point P.

As the third stage, if the light is too bright and full of saturation, the CCD camera shutter speed is increased to the level just before saturation to reduce the amount of light, and if it is dark and pre-saturation without light, it is just before saturation. The shutter speed of the CCD camera is slowed down to increase the amount of light, and the shutter speed S in a state where the focal point is focused is determined.

  As a fourth stage, the luminous intensity at the highest luminous intensity point P in the light distribution for each luminous intensity value is determined from the shutter speed S determined by the adjustment in the third stage.

It should be noted that the maximum luminous intensity point P is not a point, but is a point consisting of a predetermined number of pixels determined by the resolution of the CCD camera, and the luminous intensity value for each light distribution refers to the luminous intensity value at the highest luminous intensity point. .

  As a final fifth stage, as shown in FIG. 4, the plurality of predetermined light intensity values C are taken on the horizontal axis, and a plurality of appropriate shutter speeds S in a state in which the vertical axis is focused on one point for each light intensity value. Then, the light intensity and the appropriate shutter speed coefficient K based on the reference light source having the known light intensity are created by continuously obtaining the intersection points.

  A method of calculating the luminous intensity at the highest luminous intensity point of an unknown light using the previously created luminous intensity / appropriate shutter speed coefficient K will be described.

A light having an unknown luminous intensity is placed on the light A in FIG. 1, and the unknown light distribution on the light distribution screen 3 is captured by the CCD camera 4 and the CCD at the highest luminous intensity point of the unknown light distribution. Adjust the shutter speed to increase or decrease the shutter speed so that the camera output is in focus at one point, find the appropriate shutter speed at the time when the focus is at one point, and the luminous intensity / appropriate shutter speed to the appropriate shutter speed of the unknown light The image processing calculation unit 5 calculates the luminous intensity at the highest luminous intensity point of the unknown light distribution by multiplying by the coefficient K.

  Next, a method for calculating the light intensity at an arbitrary point of an unknown light using the light intensity / appropriate shutter speed coefficient K will be described.

  First, as described above, the appropriate shutter speed and light intensity at the highest light intensity point of the unknown light distribution are calculated, and the light intensity at the highest light intensity point P of the light light distribution shown in FIG. The brightness ratio of the point Q is calculated as, for example, 1: 0.8, and the appropriate shutter speed at the highest luminous intensity point is multiplied by the brightness ratio to calculate the appropriate shutter speed at the arbitrary point. The calculated appropriate shutter speed at the arbitrary point is substituted into the luminous intensity / appropriate shutter speed coefficient K to calculate the luminous intensity at the arbitrary point.

  As described above, the light intensity measurement method of the present invention prepares the light intensity / appropriate shutter speed coefficient K in advance based on a reference light source of known light intensity, and at the time of measurement, the appropriate shutter of the highest light intensity point of the unknown light. Multiply the speed to calculate the luminous intensity of the highest luminous intensity point, and in the case of an arbitrary point, calculate the ratio of the shutter speed to the highest luminous intensity point from the brightness ratio with the highest luminous intensity point, and calculate the arbitrary point Is substituted for the coefficient K to obtain the light intensity at an arbitrary point.

  Next, a headlight tester photometric apparatus according to Embodiment 2 of the present invention will be described with reference to FIGS.

  In FIG. 5, reference numeral 11 denotes a headlight tester. The headlight tester 11 is a carriage 11b that moves in the left-right direction on a rail laid on the floor, a column 11c that stands on the carriage 11b, and a column 11c. It is comprised from the housing | casing 11a of the rectangular parallelepiped provided so that a movement was possible.

  Next, the internal configuration of the casing 11a, which is the main part for the photometric measurement of the present invention, will be described with reference to FIG.

  A condensing lens 12 such as a Fresnel lens for receiving the light of the headlamp A to be tested is provided on the front surface of the housing 11a, and from the condensing lens 12 to the inside rear of the housing 11a. A light distribution screen 13 for receiving the converged light distribution is provided, a CCD camera 14 for detecting the light distribution is provided above the middle of the housing 11a, and for direct alignment of the light. A half mirror 15 is obliquely installed in the middle part of the casing, and a light facing screen 16 for confirming an image of the light A to be tested reflected on the half mirror 15 is located at the upper front of the casing 11a. Provided in the department.

  The system configuration of the arithmetic processing system 17 will be described with reference to FIG.

  18 is an image capturing unit for capturing the output from the CCD camera 14 as a file, 19 is an arithmetic processing unit for performing image processing and arithmetic processing composed of a CPU, and 20 is based on the reference light source of the known luminous intensity. A first storage unit 21 for storing the previously prepared luminous intensity / appropriate shutter speed coefficient K for a long period of time temporarily stores an appropriate shutter speed value immediately before the maximum luminous intensity point of light distribution is not saturated during measurement. The second storage unit 22 is a third storage unit that temporarily stores the brightness ratio between the maximum luminous intensity point and the arbitrary point of light distribution, 23 is a display control unit, 24 is a display unit such as a liquid crystal panel, 25 Indicates an operation unit, and the first storage unit 20, the second storage unit 21, the third storage unit 22, and the operation unit 25 are directly connected to the arithmetic processing unit 19, and the CCD camera 14 is further connected to the image capturing unit. Through 18 Also, the display unit 24 is connected to each of the arithmetic processing unit 19 via the display control unit 23.

  Next, a method for using the headlight tester 11 of the second embodiment will be described.

  First, the vehicle under test is stopped at a designated position in front of the headlight tester 11, the vehicle light is turned on, and the carriage 11 b is moved in the left-right direction so that either the left or right light image is reflected in the center of the light facing screen 16. And the casing 11a is moved in the vertical direction to complete the preparation for facing.

  Next, the light distribution incident on the light distribution screen 13 is captured by the CCD camera 14, and the output of the CCD camera is image-processed by the arithmetic processing unit 19 to display an isometric view of the light distribution as shown in FIG. And the portion of the minimum encircled line in the isometric view is the maximum luminous intensity point P, and there are those having a plurality of luminous intensity points depending on the type of lamp.

  FIG. 9 shows a light intensity curve in the X-axis direction of the isometric view of the light distribution shown in FIG. 8. The shutter speed of the CCD camera 14 is varied, and the CCD camera at the maximum light intensity point P of the light distribution is shown. If the analog amount is saturated, the shutter speed is increased to reduce the amount of light to the state just before saturation, and if it is not saturated, the shutter speed is decreased to increase the amount of light and the maximum luminous intensity point P is appropriate. The shutter speed S is determined, the appropriate shutter speed S is stored in the second storage unit 21, and the appropriate shutter speed S is multiplied by the luminous intensity / appropriate shutter speed coefficient K stored in the first storage unit 20 in advance. The arithmetic processing unit 19 calculates the luminous intensity C of the highest luminous intensity point P of the light distribution.

FIG. 10 shows a flowchart of the procedure for measuring the maximum luminous intensity point P of the light distribution by the headlight tester 11. As Step 1 (P1) of the flowchart, the shutter speed of the CCD camera 14 is not initially arbitrary, and FIG. may be set higher as the position of the _{S 1} shown in 9, step 2 (P2), wherein the measurement range CCD camera 14 is captured entire image brightness is preset, for example, 70% in 99% If YES, ie, step 5 (P5) as appropriate, if NO, in step 3 (P3), if the image is dark, the shutter speed is slowed to increase the light amount, and if it is too bright, the light amount is increased. In step 4 (P4), the image of the lamp light distribution after the shutter speed adjustment is taken in step 2 (P2). In step 5 (P5), shading correction processing is performed to correct density level unevenness due to the characteristics of the CCD camera elements and lens aberrations. Then, the calculation is performed in step 6 (P6). The processing unit 19 calculates the light intensity at the actual maximum light intensity point P from the shutter speed S and the brightness of the corrected screen.

  Next, calculation of the light intensity at an arbitrary point Q of the light distribution to be measured shown in the light intensity curve of FIG. 9 will be described.

  The ratio R between the luminous intensity C of the highest luminous intensity point P and the brightness C ′ of the arbitrary point Q calculated as described above is calculated. For example, when the luminous intensity of the highest luminous intensity point P is 1, the brightness of the arbitrary point Q is calculated. The brightness ratio R is calculated such that the height C ′ is 0.8, and the brightness ratio R is stored in the third storage unit 22.

  Then, the appropriate shutter speed S at the maximum luminous intensity point P is multiplied by the brightness ratio R to calculate the appropriate shutter speed S ′ at the arbitrary point Q, and the calculated appropriate shutter speed S at the arbitrary point Q is calculated. 'Is substituted into the luminous intensity / appropriate shutter speed coefficient K stored in the first storage unit 20, and the arithmetic processing unit 19 performs these calculations as the luminous intensity C' of the arbitrary point Q.

  As an application example, the headlight tester 11 of the present invention uses the arithmetic processing of the arithmetic processing unit including a storage unit that stores the light intensity and the appropriate shutter coefficient based on the light source of the known light intensity, The light intensity at an arbitrary point can be accurately calculated, and a CCD camera can be used instead of the light intensity measurement sensor.

It is explanatory drawing of the principle apparatus of the photometric measurement method of this invention. Example 1 It is an isometric view of the light distribution. Example 1 It is the luminous intensity curve figure of the light distribution. Example 1 It is explanatory drawing of the luminous intensity and the appropriate shutter speed coefficient. Example 1 It is a front view of the headlight tester of Example 2 of the present invention. It is sectional drawing of the principal part. (Example 2) It is a system configuration diagram of the arithmetic processing system. (Example 2) It is an isometric view of the light distribution. (Example 2) It is the luminous intensity curve figure of the light distribution. (Example 2) It is a flowchart figure of the luminous intensity calculation. (Example 2)

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Principle apparatus 2 Condensing lens 3 Light distribution screen 4 CCD camera 5 Image processing calculation part 11 Headlight tester 11a Case 12 Condensing lens 13 Light distribution screen 14 CCD camera 19 Calculation processing part 20 1st memory | storage part 21 2nd memory | storage Part 22 Third storage part K Luminous intensity / appropriate shutter speed coefficient

Claims (4)

A light distribution screen is provided in front of a reference light source having a known light intensity, and a CCD camera fixed at a predetermined aperture value for light distribution detection is provided toward the light distribution screen, and the light intensity of the reference light source is set on the light distribution screen. Brightness that is variable so that a plurality of predetermined light intensity values are obtained, and the light distribution for each light intensity value is detected by the CCD camera, and the shutter speed of the CCD camera is varied for each light intensity value to expand the light to the whole. if too saturated to reduce the amount of light to increase the shutter speed of the CCD camera, dark if the light is not saturated previous state a slower shutter speed of the CCD camera increases the light amount, the maximum light intensity point The appropriate shutter speed when the CCD camera output is focused on a single point is obtained, and the luminous intensity is calculated based on the appropriate shutter speed corresponding to each of these luminous intensity values. Create a proper shutter speed coefficient beforehand, at the time of measurement, the CCD camera output for the highest light intensity point of the light distribution of the unknown light will increase or decrease the shutter speed so that the state focused on one point, a focus to a point A method for measuring the luminous intensity of a headlight tester that calculates an appropriate shutter speed in a state and calculates the luminous intensity at the highest luminous intensity point of the unknown light distribution by multiplying the appropriate shutter speed of the unknown light by the luminous intensity / appropriate shutter speed coefficient .   Calculating an appropriate shutter speed and luminous intensity of the highest luminous intensity point of the unknown light distribution, and calculating a ratio of the luminous intensity of the highest luminous intensity point and the brightness of an arbitrary point of the luminous intensity distribution to be measured; The appropriate shutter speed at the arbitrary point is calculated by multiplying the speed by the brightness ratio, and the calculated appropriate shutter speed at the arbitrary point is substituted into the luminous intensity / appropriate shutter speed coefficient to calculate the luminous intensity at the arbitrary point. The method for measuring the luminous intensity of the headlight tester according to claim 1. A condensing lens for converging headlight light is provided on the front surface of the casing that can be moved vertically and horizontally, and a light distribution screen for receiving the converging light from the condensing lens in the casing and a distribution on the light distribution screen. A CCD camera fixed at a predetermined aperture value for detecting light is provided, and the output from the CCD camera is inputted so that the CCD camera output at the highest luminous intensity point of light distribution at the time of measurement is focused on one point. Increase or decrease the shutter speed and multiply the appropriate shutter speed when focusing on one point by the light intensity and appropriate shutter speed coefficient created based on a reference light source of known light intensity to calculate the light intensity at the maximum light intensity point of the above light distribution provided with an arithmetic processing unit that performs, stored in the arithmetic processing unit, the value of a suitable positive shutter speeds up to light intensity point of the light distribution of the first time the storage unit measurement for storing the intensity and appropriate shutter speed coefficient Photometric device headlight tester connects the second storage unit.   The arithmetic processing unit calculates the ratio of the brightness of the highest luminous intensity point of the light distribution and the brightness of an arbitrary point to be measured, and multiplies the appropriate shutter speed of the highest luminous intensity point by the brightness ratio to Calculate as the appropriate shutter speed at an arbitrary point, substitute the appropriate shutter speed at the arbitrary point into the predetermined coefficient, calculate the luminous intensity as the luminous intensity at the arbitrary point, and enter the luminous intensity at the highest luminous intensity point of the light distribution in the arithmetic processing unit The headlight tester photometric measurement device according to claim 3, further comprising a third storage unit for storing a brightness ratio between the headlight tester and the arbitrary point.

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