JPH057656B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical field to which the invention pertains] The present invention relates to a method for determining light distribution during investigation and inspection of irradiation light distribution in automobile headlamps and the like.

[Prior art and its problems]

Conventionally, one of the criteria for determining the light distribution of automobile headlights is, for example, the highest luminous intensity point of the light distribution pattern on the screen surface installed 3 meters in front of the headlight, or the The optical axis or the headlight irradiation reference axis is the center point of the sensor arrangement when the output values of the photoelectric sensors arranged vertically are balanced with each other between the pair of sensors, and the line connecting the headlight. In some cases, the headlights are adjusted so that this axis coincides with the normal direction.

However, because there is considerable variation in the luminous intensity distribution of the light distribution pattern caused by headlamps, there are cases where the maximum luminous intensity point is not clear, or the isoluminous curves are not concentric and the maximum luminous intensity point is biased. can be,
Adjustments based on the standards described above are often not practical.

Therefore, as a proposal to improve such standards, the center of gravity of an area surrounded by an isoluminous closed surface having a certain ratio, for example, 80% or more of the maximum luminous intensity in the light distribution pattern on the screen surface, Alternatively, within this region, a method has been considered in which a line connecting the center of gravity of the region whose opening angle is 4° to 8° as viewed from the headlamp and the headlamp is set as the optical axis or the irradiation reference axis. In this case, the center of gravity can be determined by assuming that mass points with the same mass are uniformly distributed within the area, or by calculating the center of gravity by assuming that mass points with the same mass are uniformly distributed within the area, or There is a way to find the center of gravity by assuming that a mass point exists.

However, the former standard basically uses the maximum luminous intensity axis as the irradiation reference axis for headlights, and the latter standard only targets areas where the luminous intensity is a certain ratio or higher relative to the maximum luminous intensity. This is different from the standard for actually visually recognized light distribution described below. In other words, the direction of the irradiated light that is visible is the direction of the line that connects the approximate center of gravity of the beam of light seen when it is irradiated onto a screen, etc. and the lamp, and this beam of light is determined by spatial changes in the amount of light distribution on the screen. This is an area whose outline is a point with high acceleration. It is also thought that people are dazzled when the rate of change in the amount of light that enters their eyes is high, and that they are therefore dazzled when the outline of a beam of light enters their eyes.

[Purpose of the invention]

In view of the above, the present invention captures the beam of light that has the most significant effect among the characteristics of light distribution that acts on the human eye,
It is an object of the present invention to provide a method for determining the illumination distribution of automobile headlights, etc., which determines the illumination direction that matches visual recognition or determines the light distribution that prevents dazzling effects on oncoming vehicles.

[Key points of the invention]

The present invention provides that, in the light distribution pattern of automobile headlights, etc., there is a range in which there is a linear relationship between the logarithm value logS of the area value S of the area having a predetermined luminous intensity or more and the luminous intensity, and This range is consistent even among different headlights, etc., and within the range where there is a linear relationship between the logarithm value logS of the area value S of the area whose luminous intensity is above a predetermined luminous intensity and the luminous intensity, which area is the same? This method takes advantage of the fact that the area pattern is similar to the pattern that is visually recognized as a beam of light. Set it up and
By changing the luminous intensity threshold for the observed light distribution pattern, a region corresponding to the area value S where the area value of the region equal to or greater than the luminous intensity threshold is set is determined as a light beam region, and the outline of this light beam region or the area within the light beam region is determined. A predetermined point and a reference mark for determining light distribution are displayed on a display device, and the light distribution is determined depending on whether the outline of the light beam area touches the reference mark or whether the predetermined point within the light beam area matches the reference mark. It is characterized by the fact that it is made to do so. Furthermore, if the set value of the area to be compared with the light beam region is not known, the luminous intensity threshold value is sequentially changed and the logarithm value logS of the area value S of the area whose luminous intensity threshold value or more is calculated each time,
The present invention is characterized in that the set value of the area is determined within a range in which there is a linear relationship between the logarithm value logS and the luminous intensity.

[Embodiments of the invention]

FIG. 1 is an explanatory diagram of a method of observing a light distribution pattern when implementing the present invention. When applying the present invention, the irradiation light from the headlamp 1 is projected onto the screen 2, and the surface of the screen 2 is Irradiated reflected light from TV camera 3
The luminous intensity of the headlight 1 at each point on the screen 2 is measured by observing through the screen.

The beam of light emitted from the headlamp 1 irradiated onto the screen 2 in this manner will be explained with reference to FIG. 2. Second
Figure a shows, for example, a horizontal luminous intensity distribution on the screen 2, with luminous intensity I on the vertical axis and distance on the horizontal axis. Figure 2b shows a curve obtained by differentiating the light intensity distribution curve shown in Figure 2a, and the second
Figure c shows a curve obtained by further differentiating the curve shown in Figure 2b. As mentioned above, the beam of light is an area defined by the point where the spatial change in the amount of light distribution on the screen has a high acceleration (i.e., the second derivative of the light intensity distribution curve), so the outline of the beam of light is shown in Figure 2c. It exists in the parts indicated by A and B of the curve shown.

Regarding the characteristics of the light distribution patterns of different types of lamps L1 to L3 observed as shown in Figure 1, the horizontal axis shows the luminous intensity value at each point in the light distribution pattern, and the vertical axis shows the luminous intensity above a certain level. Figure 3 shows the logarithm value logS of the area value S of the area on the screen surface having the luminous intensity of There is a range of area values logSA to logSB. Furthermore, if we look at the luminous intensity I corresponding to this range logSA~logSB, it almost corresponds to the range between the broken lines C and D in Figure 2a, and this range corresponds to the area I, where the light beam exists as shown in Figure 2c. It matches the luminosity of b. In this way, the logarithm of the area value of the binary image of the region within the beam is
There is a linear relationship between logS and luminous intensity I. logSA
It is known from experience that it is within the range of ~logSB, and in other ranges the relationship between logS and luminous intensity I is curved and not a linear relationship, so it is not an area within the beam.

In this way, the area pattern of area values in which logS and luminous intensity I have a linear relationship is similar to the pattern that is visually recognized as a beam of light, and according to visual recognition, when the eyes are wide open, the area pattern of the area value It is similar to the area pattern with area value SA, which is larger in the value range, and the light beam when viewed with a dim view is similar to the area pattern with area value SB, which is smaller in the area value range.

Since there is a correspondence between the luminous intensity I of a beam and the area value, the present invention provides an area value corresponding to this beam as a set value, and displays a screen surface having a luminous intensity equal to or higher than a certain luminous intensity that matches this area setting value. This method attempts to capture a beam of light by determining the area of , and determine the light distribution based on this beam of light, and an example thereof will be described below.

FIG. 4 is a functional block diagram of an apparatus for implementing the present invention, in which 4 is a television camera;
5 is a binarization means, 6 is an image memory, 7 is an area counting means, 8 is an area value comparison means, 9 is a setting means, 10
11 is a switch, 11 is a combining means, and 12 is a display means (CRT display device). The television camera 4 images the screen 2 as shown in FIG. 1, and sends the image signal to the binarization means 5. The binarization means 5 performs binarization by comparing this imaging signal with a predetermined luminous intensity threshold, and this luminous intensity threshold increases or decreases by a predetermined unit amount in response to a setting change command from the area comparing means 8. . The signal binarized by the binarization means 5 is stored in the image memory 6 for one frame, and is also applied to the area counting means 7 to count the number of pixels having a luminous intensity greater than the luminous intensity threshold. The counted value of the area counting means 7 is compared with the area setting value from the setting means 9 in the area value comparing means 8. The setting means 9 stores area setting values according to the vehicle type or headlight, and the area setting values read out by an external selection operation are sent to the area value comparison means 8. This area setting value has a logarithm value of logSA~ as shown in Figure 3.
It can be set arbitrarily as long as it falls within the range of logSB. The area value comparing means 8 compares whether the counted value from the area counting means 7 is equal to the area setting value from the setting means 9, and if the counted value is small, sets a predetermined luminous intensity threshold value to the binarizing means 5. A setting change command is issued to lower the luminous intensity threshold by a predetermined unit amount, and if the count value is large, a setting change command is issued to the binarization means 5 to increase the luminous intensity threshold by a predetermined unit amount.
By repeating such a procedure, the area count value and the area setting value become equal. The threshold value at this time becomes a value corresponding to the luminous intensity of the beam of light, and the outline of the beam of light is detected. As a result, the area comparing means 8 sends a close command to the switch 10, and the image memory 6
The image data within is sent to the synthesizing means 11, where it is synthesized (overlaid) with the reference mark (reference line or reference point) from the setting means 9, and displayed on the display means 12. In addition to the above-mentioned area setting values, the setting means 9 stores data on reference marks for determining light distribution according to the vehicle type, and the reference marks are displayed in response to an external selection operation. Means 12
will be displayed at a predetermined location.

A display example on this display means 12 is shown in FIG. FIG. 5a is an example in which the light beam outline H is in contact with the reference mark B1, and the reference mark B1
When the beam outline H and the beam outline H are not in contact with each other, the display means 1
The light distribution is set by adjusting the headlight and touching it while looking at the display 2. FIG. 5b is also an example in which the beam outline H is brought into contact with the reference mark B2. In this way, the reference marks B1 and B2 are arbitrary, and the light may be distributed so that the upper outline of the light distribution pattern area is in contact with a certain reference line as shown in FIG. 5a, or as shown in FIG. 5b. As shown, light distribution may be performed so that the upper side, left and right sides, or both sides of the light distribution pattern area are in contact with a certain reference line. Furthermore, the light distribution may be determined by providing a reference mark B3 as shown in FIG. good. In this case, it is necessary to calculate the center of gravity G and display it on the display means 12 with a + mark or the like. As mentioned above, the center of gravity G can be found by assuming that mass points with the same mass are uniformly distributed within the light distribution pattern area, or by assuming that there are mass points with a mass equivalent to the amount of light at that point. In the former case, the center of gravity can be found by calculating the average value of the total sum of the coordinates of each point in the horizontal and vertical directions, and in the latter case, For each point in the light distribution pattern area, the mass of each point is also memorized, and the total sum of the values obtained by multiplying each coordinate by the mass is divided by the total mass for each horizontal and vertical direction. It can be found by Such calculation of the center of gravity can be performed using data in the image memory 6 by an arithmetic device (not shown).

Next, the configuration of the device for carrying out the present invention will be explained in the sixth section.
This will be explained based on the diagram. In Fig. 6, 13 is a television camera, 14 is a binarization circuit, 15 is an image memory, 16 is an output port, 17 is a CPU, and 18 is a memory, which process the image of the light distribution pattern on the screen. The system is configured. Further, in FIG. 6, 19 is an interface, 20 is a CPU, 21 is a memory, 22 is a CRT display device, and 23 is an input port, which constitute a man-machine interface.

In such a configuration, input port 2 is first
3, vehicle type data, reference mark data for the vehicle type, and area value data for the vehicle type are respectively inputted as various setting values, and under the control of the CPU 20, the reference mark data and the reference mark data are stored in the memory 21 in correspondence with the vehicle type data. Area setting value data is stored. As a result, from now on, when vehicle type data is input through the input port 23, the reference mark data and area setting value data corresponding to this vehicle type are read out. The fiducial mark data is sent to the CRT display device and
Reference marks B1, B as shown in figures a, b, c
2, B3 is displayed. Further, the area setting value data is stored in the memory 18 via the interface 19 and the CPU 17. In the image processing system, a television camera 13 captures an image of the light distribution pattern of the screen shown in FIG. . This binarization circuit 1
The luminous intensity threshold for binarization of 4 is determined by a command from the output port 16.

The CPU 17 adjusts the threshold so that the area having a luminous intensity equal to or higher than the threshold matches the area setting value sent from the man-machine interface (within the tolerance range), calculates the outline of the beam, and sends it to the man-machine interface. However, the operation flowchart at that time is shown in FIG. As shown in FIG. 7, the CPU 17 reads image data from the image memory 15 (step S1), counts the number of images whose level is "1" from among this image data, and calculates the area value (step S2). ). This calculated area value is compared with the area setting value sent from the man-machine interface (step S3), and if they do not match, it is determined whether it is larger than the area setting value (step S4). If it is larger than the area setting value, it means that the luminous intensity threshold for binarization is too small, and a command to increase the luminous intensity threshold by a predetermined unit amount is given to the binarizing circuit 14 via the output port 16 (step S5). . Conversely, if it is smaller than the area value, the luminosity threshold for binarization was too large, so
A command to lower the luminous intensity threshold by a predetermined unit amount is given to the binarization circuit 14 via the output port 16 (step S6). Since the luminous intensity threshold of the binarization circuit 14 is changed in this way, the image data of the image memory 15 is also changed. So, return to step S1 again,
The changed image data is taken in and similar processing is performed until the calculated area value matches the area setting value. If it is determined that there is a match in step S3, 2
The contour data of the converted image is transferred to interface 1.
9 to the man-machine interface (step S7) to end the operation. When determining the light distribution as shown in Figure 5 a and b, it is sufficient to simply send the contour data, but when determining the light distribution using the center of gravity as shown in Figure 5 c, image processing It is better to calculate the coordinates of the center of gravity on the system side and send it to the man-machine interface.

On the man-machine interface side, the contour data and center of gravity coordinate data sent from the image processing system side are sent to the CRT display device 22.
Figure 5 a, b, and c are superimposed on the reference marks mentioned above.
A display as shown in the figure is displayed, and the light distribution is adjusted while looking at the screen of this CRT display device. At this time, it goes without saying that the image processing system side obtains the contour pattern and the coordinate data of the center of gravity of the light distribution pattern that has been adjusted each time, and sends it to the CRT display device 22.

In addition to the method shown in Fig. 5, various methods of adjusting the light distribution can be considered. For example, instead of the center of gravity, as shown in Fig. 8, the center coordinates (X ₀ , Y ₀ ) can also be used. How to determine the center coordinates (X ₀ , Y ₀ ) in this case will be explained using FIGS. 9 and 10.

First, from the image data in the image memory 15, a series (segments) of points equal to or higher than the threshold level in the scanning line direction of the television camera 13 is examined, and a number (i=0 to n) is given to each segment in order from the top. The Y coordinate, start point X coordinate (X _L ), and end point X coordinate (X _R ) of each segment are detected and stored in the memory 18 in the order of segment numbers. In addition, the end point X coordinate (X _R )
Instead, the length of the segment (number of pixels) can be used (the end point X coordinate is obtained as the sum of the start point X coordinate and the length of the segment). Therefore, the image data is divided into segments i with i=0 to n as shown in Fig. 9, and the Y coordinate, starting point X coordinate ( _XL ), and ending point X coordinate ( _XR ) are determined. Center coordinates of rectangle B4 touching H (X ₀ , Y ₀ )
For X ₀ , it is found as the value of 1/2 of the sum of the minimum X _LMIN of the start point coordinates X _L of each segment and the maximum X _RMAX of the end point coordinates X _R ,
For Y ₀ , Y of segment 0 and segment n
It is calculated as the value of 1/2 of the sum of the coordinates. Therefore,
Using the data stored in the memory 18, the CPU 17 first sets i=0, the minimum starting point X coordinate X _LMIN , and the minimum Y coordinate _MIN to the maximum hexadecimal value FF, as shown in the flowchart of FIG.
After setting the maximum end point X coordinate X _RMAX to 0 (step S1), compare the starting point X coordinate X _L with the minimum starting point X coordinate X _LMIN for segment 0 (step S2),
If the coordinate X _LO is smaller than the coordinate X _LMIN , the coordinate X _LO is updated as a new coordinate X _LMIN (step S3).
Similarly, the end point X coordinate X _RO and the maximum end point X coordinate
Compare and update X _RMAX (steps S4, S5), Y coordinate
Comparison and update of Y ₀ and minimum Y coordinate Y _MIN (step S6,
S7), after comparing and updating the Y coordinate Y ₀ and the maximum Y coordinate Y _MAX (steps S8, S9), proceed to the next numbered segment (step S10) and check whether this segment is the final segment. (step S11), and if it is not the final segment, the process returns to step S2 and performs the same process. When this process is performed up to the final segment, the minimum starting point X coordinate X _LMIN and maximum ending point X coordinate as shown in Figure 9 are obtained.
X _RAMX and the Y coordinates Y _MIN and Y _MAX of segments 0 and n are determined, so in step 13 the center coordinates are determined.
_{X 0 , Y 0} = _{X 0 = X LMIN} + S13).

The above example deals with the case where the interview setting value corresponding to the light beam is known, but if the area setting value corresponding to the light beam is unknown, the linear relationship between logS and luminous intensity I as shown in Fig. 3 is used. The area setting value can be found as follows by using the property that .

In other words, since the light distribution characteristic curve is almost a straight line in the range of logSA to logSB, the range corresponding to logSA to logSB can be determined by finding the section where the second-order differential value obtained by second-order differentiation of the light distribution characteristic curve is less than a certain value. It can be considered as Therefore, in the present invention, first, in the configuration shown in FIG.
The luminous intensity threshold of No. 4 is sequentially changed from the minimum value by a unit amount ΔT, and each time the area value S _o of a region with luminous intensity equal to or higher than the threshold level is determined and its logarithm log S _o is calculated. Next, to smooth this logarithm logS _o and remove noise, the logarithm of the previous and subsequent thresholds logS _o-1 ,
Calculate the sum with logS _o+1 , and set the sum or 1/3 of the sum as the logarithm value F _o of the threshold. Here, the differential value is expressed by dF/dt≈F _o −F _o+1 /ΔT, and the second-order differential value is expressed by the following equation.

d ² F／dt ² ≒F _o −F _o+1 ／ΔT−F _o+1 −F _o+2 ／ΔT／Δ
T=F _o −2F _o+1 +F _o+2 / (ΔT) ^2In this formula, (ΔT) ² is a constant value, so d ² F/dt ² is F _o −2F _o+1 +F _o+2 It will be proportional to. Therefore, F _o −2F _o+1 +F _o+2 is calculated to find a luminous intensity threshold that is below a certain value, and logS _o at this luminous intensity threshold is set as the area setting value. Such a calculation may be performed by the CPU 17 in the configuration shown in FIG. 6, and the obtained area setting value may be sent to the man-machine interface side.

In the above description of the embodiment, the light distribution pattern is observed by capturing an image of the light irradiated onto a screen or the like using a television camera, but the light distribution pattern can be directly observed using a photoelectric sensor such as a photocell arranged in a matrix. It is also possible to perform this by receiving light.

〔Effect of the invention〕

According to the present invention, since the light distribution is determined based on the light beam, which is the light distribution pattern that has the most significant effect on human vision, it is possible to adjust the light distribution that most closely matches visual recognition. Further, according to the present invention, not only the irradiation axis of the lamp but also the contour of the beam of light is set within a reference range, so that it is possible to prevent dazzling of oncoming vehicles when passing each other.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of the light distribution pattern observation method according to the present invention, FIG. 2 is a diagram for explaining the beam of irradiated light, and FIG. 3 is a diagram showing the light distribution characteristics of different types of headlamps. FIG. 4 is a functional block diagram of a device for implementing the present invention, FIGS. 5 and 8 are diagrams showing the display screen of a CRT display device when determining light distribution according to the present invention, and FIG. A schematic configuration diagram of an apparatus for carrying out the invention, FIG. 7 is a flowchart showing the process for determining the outline of a beam of light, FIG. 9, and FIG.
Figure 0 shows an explanatory diagram and a flowchart of processing when finding the center of a rectangle that is in contact with the beam outline. 1... Headlight, 2... Screen, 3, 4, 1
3... Television camera, 5... Binarization means, 6,1
5... Image memory, 7... Image counting means, 8...
Area value comparison means, 9...setting means, 10...switch, 11...composition means, 12...display means, 1
4...Binarization circuit, 16...Output port, 17,
20...CPU, 18, 21...Memory, 19...
...interface, 22...CRT display device, 23...input port.

Claims (1)

[Claims] 1. In a light distribution pattern obtained by observing light irradiation from an automobile headlamp, etc. in a cross section in front of it, the logarithm value logS of the area value S of an area having a predetermined luminous intensity or more and the luminous intensity An area value S within a range having a linear relationship between them is arbitrarily selected and set in advance, and by changing the luminous intensity threshold for the observed light distribution pattern, the area value of the area whose luminous intensity is equal to or greater than the luminous intensity threshold is preset. Find a region matching the area value S as a beam region,
The outline of the beam area or a predetermined point within the beam area and a reference mark for determining light distribution are displayed on a display device, and the outline of the beam area touches the reference mark, or the predetermined point within the beam area is the reference mark. A method for determining irradiation light distribution for automobile headlights, etc., characterized in that the light distribution is determined depending on whether the light distribution matches a mark. 2. In the irradiation light distribution determining method according to claim 1, the luminous intensity threshold is sequentially changed and the logarithm of the area value S of the area whose luminous intensity is equal to or larger than the luminous intensity threshold each time is determined.
1. A method for determining irradiation light distribution for automobile headlights, etc., comprising: calculating logS, and determining a setting value for area value S within a range in which there is a linear relationship between the logarithm value logS and luminous intensity.