A method for calibrating a vehicle headlamp on a toe-in testing station

Abstract

This invention discloses a calibration method for vehicle headlights on a toe-in testing platform, determining the optical state of the headlights; confirming the toe-in parameters and stability of the headlights based on the toe-in testing platform calibration; confirming the vehicle body dimensions and stability based on the vehicle's three-coordinate system; calibrating the Nth set of headlights of the test vehicle to pass the toe-in testing platform calibration; conducting road tests on the test vehicle under various road conditions; after the road tests, calibrating the test vehicle again based on the toe-in testing platform to verify whether the width and height of the Nth set of headlights of the test vehicle are qualified; N≥2. This invention establishes a standard calibration method for calibrating vehicle headlights on the OEM assembly toe-in testing platform, comprehensively considering various influencing factors, and has the advantages of short time consumption, low cost, and simple, fast, and efficient operation, with broad application prospects in vehicle regulatory testing.

Description

Technical Field

[0001] This invention belongs to the field of automotive lighting verification technology, specifically relating to a calibration method for automotive lights on a beam test bench, which can be widely applied in the field of automotive lighting calibration technology. Background Technology

[0002] Headlights are one of the most important functional components of a vehicle, with the high and low beams being a crucial part of active safety. While providing drivers with ample road illumination and a wide field of vision, headlights must also ensure they do not dazzle or interfere with other road users. Theoretically, once a qualified headlight is installed on a vehicle, its height and horizontal width do not require adjustment. However, due to assembly process and vehicle dimensions errors, the headlight may shift position on the vehicle. Furthermore, the illumination distance is long (regulations stipulate a 10-meter beam distance), and even slight changes in vehicle posture can cause significant beam deviations. To ensure that a qualified headlight maintains its correct height and width after installation, headlight inspection and adjustment on the front beam are necessary. This ensures that the headlights still meet regulatory requirements after the vehicle rolls off the production line. For OEMs, to reduce the workload of headlight adjustments, they typically require headlight manufacturers to adjust the horizontal width of the finished headlights to the median value based on OEM-calibrated headlight samples. Theoretically, after calibration, the headlights do not require further adjustment upon installation. During the calibration and adjustment of lights, various problems often arise, requiring engineers to spend a significant amount of time investigating the root causes. To overcome this predicament, a complete calibration method and troubleshooting strategies are needed to make light calibration more efficient and scientifically sound. Summary of the Invention

[0003] To address the technical problems existing in the prior art, this invention provides a calibration method for vehicle headlights on a front beam testing bench. This method establishes a standard calibration method for calibrating vehicle headlights on the OEM assembly front beam testing bench. It can comprehensively consider various influencing factors and has the advantages of short time consumption, low cost, and simple, fast and efficient operation. It has broad application prospects in vehicle regulatory testing.

[0004] This invention discloses a method for calibrating vehicle headlights on a toe-in testing platform to determine the optical state of the headlights; confirming the toe-in parameters and stability of the headlights based on the toe-in testing platform calibration, and confirming the vehicle body dimensions and stability based on the vehicle's three-coordinate system; calibrating the Nth set of headlights of the test vehicle to pass the toe-in testing platform calibration, conducting road tests on the test vehicle under various road conditions, and after the road tests are completed, calibrating the test vehicle again based on the toe-in testing platform to verify whether the width and height of the Nth set of headlights of the test vehicle are qualified; N≥2.

[0005] In a preferred embodiment of the present invention, determining the optical condition of the headlights includes confirming the stability of the light distribution performance of the same batch of headlights and confirming the stability data of the lamp width and lamp height of the same batch of parts on the front beam testing bench of the vehicle manufacturer.

[0006] In a preferred embodiment of the present invention, the calibration and confirmation of the headlight headlight parameters based on the headlight headlight test bench includes: calibrating the theoretical position of the headlight box capture; periodically checking the calibrated headlight headlight test bench with a standard template to ensure that the capture position of the headlight box is correct; wherein the stability confirmation of the headlight headlight parameters requires randomly selecting a vehicle and checking the headlight width and headlight height data on each calibration channel to verify whether the headlight width and headlight height data of the left and right sides of the same vehicle are consistent on different test channels.

[0007] In a preferred embodiment of the present invention, the vehicle body size and stability are confirmed based on the three-coordinate system of the vehicle body. This includes mapping the fixed points and positioning points of the headlights on the frame, fenders and other environmental components, investigating the vehicle body size status of the same batch of parts, and in the stability data of the headlight light distribution performance, under the premise of meeting national standards, the luminous flux of each headlight in both low and high beams should not be less than 80% of that of the optical sample in the design stage.

[0008] In a preferred embodiment of the present invention, the lamp width and lamp height of the same batch of parts on the front toe test bench of the vehicle factory have the same variation trend.

[0009] In a preferred embodiment of the present invention, when the calibrated toe detection station is periodically inspected using a standard template, the difference in lamp width and lamp height between the channels of each toe detection station is required to be no more than 0.5%.

[0010] In a preferred embodiment of the present invention, the corresponding difference between the headlight width and headlight height data of the left and right sides of the same vehicle on different test channels is no greater than 0.5%.

[0011] In a preferred embodiment of the present invention, when performing a three-coordinate measurement on the vehicle body, the deviation between the measured value and the theoretical data should be less than 0.5 mm.

[0012] In a preferred embodiment of the present invention, the acceptable range for lamp width is -1.7% to 3.5%, and the acceptable range for lamp height is less than -1.0%.

[0013] In a preferred embodiment of the present invention, the first set of vehicle lights that has passed verification is kept at the OEM factory to help determine the cause of calibration problems in actual production; the second set of vehicle lights that has passed verification is kept at the lighting factory to verify the lighting inspection station at the lighting factory at any time.

[0014] The beneficial effects of this invention are: This invention establishes a standard calibration method for calibrating vehicle headlights on the OEM assembly beam test bench, which can comprehensively consider various influencing factors and has the advantages of short time consumption, low cost, and simple, fast and efficient operation. It has broad application prospects in vehicle regulatory testing. Attached Figure Description

[0015] Figure 1 This is a schematic diagram illustrating the definition of the low beam width in a calibration method for vehicle headlights on a beam testing platform according to the present invention.

[0016] Figure 2 This is a schematic diagram illustrating the principle of forming the cutoff line between light and dark in a calibration method for vehicle headlights on a beam testing platform according to the present invention.

[0017] Figure 3 This is a schematic diagram illustrating the principle of forming the cutoff line between light and dark in a calibration method for vehicle headlights on a beam testing platform according to the present invention.

[0018] Figure 4 This is a schematic diagram illustrating the principle of forming the cutoff line between light and dark in a calibration method for vehicle headlights on a beam testing platform according to the present invention.

[0019] Figure 5 This is a schematic diagram of the transition zone of a calibration method for vehicle lights on a beam testing platform according to the present invention;

[0020] Figure 6 This invention relates to a calibration method for vehicle headlights on a beam testing platform, specifically the calibration process for headlights on the beam testing platform.

[0021] Figure 7 This is a schematic diagram of a lens imaging device for a method of calibrating a vehicle headlight on a beam testing platform according to the present invention. Detailed Implementation

[0022] The technical solutions (including preferred technical solutions) of the present invention will be further described in detail below with reference to the accompanying drawings and by way of listing some optional embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0023] This invention discloses a method for calibrating vehicle headlights on a toe-in testing platform. The method involves determining the optical state of the headlights; confirming the toe-in parameters and stability of the headlights based on the toe-in testing platform calibration; confirming the vehicle body dimensions and stability based on the vehicle's three-coordinate system; calibrating the Nth set of headlights of the test vehicle to pass the toe-in testing platform calibration; conducting road tests on the test vehicle under various road conditions; and after the road tests, recalibrating the test vehicle based on the toe-in testing platform to verify whether the width and height of the Nth set of headlights are qualified; N≥2.

[0024] The toe-in testing station of this invention is a device used to inspect and calibrate tires and lights according to national standards after a vehicle comes off the production line. This patent only discusses the testing of lights. This device includes some structural components (including image capture), but these are not within the scope of this patent. This patent discusses methods or processes for quickly and accurately calibrating lights.

[0025] The specific calibration steps of this invention are as follows:

[0026] 1) Confirmation of headlight optical performance before calibration. Main confirmations include:

[0027] a) The stability of the light distribution performance of headlights in the same batch recently;

[0028] b) Stability data of lamp width and lamp height of the same batch of parts on the front toe test bench of the vehicle plant;

[0029] 2) Calibration of the toe-in test bench: Vehicle manufacturers typically calibrate their toe-in test benches periodically during final assembly. The calibration process consists of two parts:

[0030] a) Calibration of the theoretical position of the lightbox capture;

[0031] b) Periodically check the calibrated toe detection platform using a standard template to ensure the correct capture position of the light box.

[0032] 3) Confirmation of headlight toe stability: A vehicle needs to be randomly selected, and the headlight width and height data need to be checked on each calibration channel. The consistency of headlight width and height data between the left and right headlights on different test channels needs to be verified. The headlight toe testing bench should have at least two test channels. One channel is used for calibration. After calibration, the relevant parameters can be imported into the computers of other test channels for software parameter updates. This allows other channels to maintain the same parameters for testing the vehicle's lighting.

[0033] 4) Vehicle body three-coordinate test: mainly to perform three-coordinate testing on the fixed points and positioning points of the headlights on the frame, fenders and other environmental parts, and to investigate the vehicle body size status of the same batch of parts.

[0034] 5) Confirmation of the stability of vehicle body dimensions in the same batch: Survey of the dimensional status under actual vehicle installation conditions.

[0035] 6) Front beam calibration of the first set of lights: Park the new car on the front beam assembly line and check the width and height of the left and right headlights according to the front beam operation procedure. If the width and height are found to be unqualified, calibrate them to the qualified position respectively.

[0036] 7) Bumpy road test: Drive the vehicle with the headlights calibrated onto the track and conduct a road test for about 20 minutes under various road conditions.

[0037] 8) After the road test is completed, re-align the vehicle with the headlights. Check the headlight width and height to see if they are within the acceptable range. If they are, remove the headlights from the vehicle and seal the adjusting nuts for the headlight width and height with glue. Record the calibration values ​​on the headlight housing. If they are not within the acceptable range and the deviation is large, repeat steps 6 and 7 to calibrate the lights again.

[0038] 9) After the first set of lamps is calibrated, the second set of lamps is calibrated using the same method. The purposes of the two sets of calibration lamps are as follows: one set of calibration lamps is kept at the main equipment manufacturer to help analyze the causes of calibration problems in actual production; the other set of calibration lamps is kept at the lighting fixture manufacturer to verify the light inspection station at the lighting fixture manufacturer at any time.

[0039] As a preferred option, the stability data of the light distribution performance of the headlights, while meeting national standards, requires that the luminous flux of the low and high beams of each headlight not be less than 80% of that of the optical sample in the design stage;

[0040] As a preferred option, the changes in lamp width and lamp height of the same batch of parts on the front toe test bench of the vehicle manufacturer are basically the same.

[0041] As a preferred option, when periodically inspecting the aforementioned calibrated toe-in testing stations using a standard template, the difference in lamp width and lamp height between the channels of each toe-in testing station should not exceed 0.5%.

[0042] As a preferred option, the difference in headlight width and height data between the left and right headlights of the same vehicle on different test tracks should not exceed 0.5%;

[0043] As a preferred option, when performing a three-coordinate measurement on the vehicle body, the deviation between the measured value and the theoretical data should be less than 0.5mm.

[0044] As a preferred option, the acceptable range for lamp width is -1.7% to 3.5%, and the acceptable range for lamp height is less than -1.0%.

[0045] This invention primarily targets headlights for passenger vehicles, but is also applicable to headlight calibration for commercial vehicles. The preferred embodiment described above refers to a test scheme that simulates a real fault environment, derived after multiple tests (under different test conditions). The lamp width described above is defined as the range of horizontal variation of the inflection point (15° or 45°) of a light screen placed 10 meters directly in front of the vehicle, with the low beam on. For left-hand drive vehicles, the range is specified as -170mm to 350mm, where the left side of the vehicle is negative and the right side is positive. See [link to relevant documentation]. Figure 1 .

[0046] The headlight height described above is defined as the downward tilt angle of the horizontal segment of the cutoff line of a light screen placed 10 meters in front of the vehicle with the low beams on, relative to the horizontal plane of the center of the light source. Generally, the tangent of this downward tilt angle should be less than -1.0%.

[0047] The aforementioned 15° or 45° cutoff line refers to: when a screen is placed 10 meters in front of the vehicle, and the low beams are turned on, a boundary line between light and dark is formed on the screen, such as... Figure 1 As shown. ECE regulations specify two different forms of near beam cutoff lines: one is where, on the light distribution screen, the left side of the cutoff line coincides with the horizontal reference line (hh), and the right side forms a 15° angle with the horizontal reference line, commonly referred to as the 15° cutoff line. The other is projected onto the screen in a Z-shape, with the left portion of the cutoff line 250mm below the horizontal reference line, and the right portion forming a 45° angle with the horizontal reference line, commonly referred to as the 45° cutoff line.

[0048] National standards generally refer to ECE regulations. According to GB7258 lighting system requirements, a light screen should be placed 10 meters in front of the vehicle from the center of the low beam source of the headlights. The height of the inflection point of the cut-off line (15° or 45°) of the headlights for passenger vehicles should be between 0.7H and 0.9H (where H is the reference center height of the headlights). Regarding width (commonly known as headlight width), the inflection point of the cut-off line should not deviate more than 170mm to the left and more than 350mm to the right. As for luminous intensity, the luminous intensity of a single headlight's high beam (generally low beam plus high beam) should be at least greater than 30,000 cd, and the sum of the luminous intensities of the left and right high beams should not exceed 220,000 cd. Under current technology, the normal range for halogen headlight luminous intensity is generally 40,000 to 50,000 cd, and for LED headlights, it is 50,000 to 70,000 cd.

[0049] Table 1. Regulations on Low and High Beams for Passenger Vehicles

[0050]

[0051] Based on the above theoretical analysis, the calibration method for the headlight on the toe-in testing platform is described in detail below:

[0052] The stability of the headlight's optical performance has been confirmed.

[0053] For the same batch of headlights (of the same vehicle model, calibrated 2-3 times during the development phase depending on the vehicle's dimensions), the stability of optical performance needs to be determined based on the provided light distribution report. During the design phase, the vertical HV point height of the high beam must not exceed 0.2H (where H is the height of the low beam's optical center from the ground) of the low beam's inflection point. Figure 2-4 There are two scenarios as you can see: Figure 2 In the middle, the HV point and the inflection point coincide. Figure 3The cutoff lines do not coincide; due to ECE regulations (EU regulations), there are two types of light distribution methods. One is that on the light distribution screen, the left side of the cutoff line coincides with the horizontal reference line hh, and the right side of the cutoff line forms a 15° angle with the horizontal reference line. The other light distribution method projects the light onto the screen in a Z-shape, with the left part of the cutoff line 250mm below the horizontal reference line, and the right part forming a 45° angle with the horizontal reference line. In China, the near-light and near-light cutoff lines generally adopt a Z-shape. Inflection point: the intersection of the horizontal segment and the upward-sloping portion of the cutoff line. The injection molding and aluminizing quality of the reflector must be stable, the cutoff line must be smooth, and the levelness and sharpness measurements of the cutoff line in the light distribution room must meet the requirements (levelness < 0.2, sharpness 0.2–0.45). Smoothness is defined as follows: above the red line (cutoff line) is the dark area, and below the red line is the illuminated area. Ideally, the red line should be a very clear line (projected onto a screen: a white wall). However, due to manufacturing defects such as the quality of the aluminum plating on the headlight inner reflector, this line is not clear (smooth), making it impossible to capture the inflection point on the toe-in test platform. Smoothness is defined as the clarity of the cut-off line (between 0.2 and 0.45), and the horizontality of the cut-off line is required to have a fluctuation range of + / -0.1mm. The method for calculating the low beam cut-off line should be confirmed; generally, the optimized graphic feature method is more accurate. The online light inspection equipment must be able to monitor specific points of the low beam headlights (25L, 25R, 50L, 50R, 75R, Zone 4; the diagram below shows the low beam projected onto the screen according to GB4785. Zone 4 is a transition zone, representing the illumination of the entire lane width within 25 to 50 meters in front of the vehicle; 25L represents the illuminance 25 meters to the left front of the vehicle, 75R represents the illuminance 75 meters to the right front of the vehicle, and so on). At a test voltage of 13.2V, 75R ≥ 25lx, 50R ≥ 20lx, 50V ≥ 6lx, 25R ≥ 5lx, 25L ≥ 5lx, and IV ≥ 5lx. The setting of the median low beam inflection point by the lighting manufacturer is determined by the low beam inflection point position marked on the vehicle body by the OEM. If the equipment is automatic dimming, the tolerance for the median low beam inflection point is ±0.5%, which can be considered as drawing a circle centered on the theoretical position of the inflection point; the actual inflection point should be within this circle. If the equipment is manually dimmed, the median control tolerance is ±0.8%. All headlights that pass the light inspection should have a light inspection pass mark on the lamp housing.

[0054] Assuming the single-lamp optical performance remains stable, investigate the test data of new vehicle headlights on the front beam testing platform within the past month. This data can generally be directly exported from the computer of the final assembly front beam testing platform. Among this data, special attention should be paid to the data before and after adjusting the left and right headlight widths, and it should be confirmed whether the headlight width was offset in a certain direction before adjustment. If it was offset in a certain direction, the specific cause needs to be identified.

[0055] The condition of the headlights. Before calibrating the headlights, the dimensions of the headlights must be stable, and the width and height data of the headlights must be qualified and stable before leaving the factory. Regarding the headlight width, since the OEM generally does not adjust the headlight width on the whole vehicle, the headlight manufacturer needs to ensure that the horizontal position of the cut-off line inflection point is as close as possible to the median value of 0.9% (the national standard requires a horizontal range of -1.7% to +3.5%).

[0056] Confirm the headlight low beam cutoff line type (15° or 45° cutoff line) with the OEM's final assembly process. If it's a module, identify the relevant vehicle model it's used in and confirm the headlight capture algorithm on the toe-in test bench. Then set the headlight detection parameters on the toe-in test bench, including: high beam optical center height from the ground, center point distance, low beam optical center height from the ground, and center point distance. Confirm that these parameters match the theoretical optical center coordinates. Once the vehicle dimensions and process parameters are confirmed, use a stable vehicle body to calibrate the headlight width. Center point distance: refers to the distance between the light source centers of the low beam or high beam of the two headlights (Y-axis distance). Using the above Y-axis and Z-axis distances, if a light screen is placed 10 meters in front of the vehicle, the theoretical optical centers of the low beam and high beam can be determined.

[0057] Calibration of the headlight capture position: This involves using infrared light to calibrate the headlight capture position, ensuring that the capture position of the front beam test bench is as close as possible to the theoretical position of the headlight's HV point. Calibration is typically performed monthly. The purpose of infrared equipment calibration is to ensure that the front beam equipment itself is not deviated from its theoretical value. A simple prototype simulating a complete vehicle is usually placed on the front beam test bench, and the headlight beam is then calibrated to the theoretical value. This process is called calibrating the front beam test bench (or calibrating the equipment). Because vehicle assembly plants don't produce many vehicles, each vehicle must be tested on the front beam test bench, inevitably leading to deviations in the front beam equipment calibration. Therefore, calibration is generally performed weekly using the aforementioned prototype. If the result is OK, infrared equipment calibration is unnecessary; if NOK, recalibration is required.

[0058] After calibrating the aforementioned light boxes, the toe-in testing platform needs to be tested. The testing method involves placing a prototype simulating the theoretical position of a vehicle headlight on the toe-in track. The width and height values ​​displayed on the toe-in track are used to determine if the requirements are met. If there are multiple test channels, each channel must be checked using a prototype. Generally, for the same test prototype, the deviation in headlight width and height across different test channels should not exceed 0.5% for the toe-in testing platform to be considered functioning correctly.

[0059] Consistency confirmation of the toe-in testing platform. Typically, the toe-in testing platform area in the OEM assembly plant has at least three toe-in channels. One channel is primarily used for the calibration of the toe-in testing platform itself. This calibration work consists of two parts: ① Calibrating the HV capture position of the headlight box to the theoretical position. This is generally done using an infrared tester to calibrate the theoretical capture position of the headlight width and height to the theoretical values, usually once a month depending on production. ② Monitoring using a template, generally once a week to check if the capture position is still at the theoretical position. The other two channels are used for the calibration and testing of vehicle lights on the production line. When calibrating the headlights at a certain stage of the project, it must be ensured that the headlight width and height values ​​for the same vehicle in the three channels do not exceed 0.5%. Otherwise, the calibration results will vary significantly due to factors related to the toe-in testing platform equipment.

[0060] 1. Confirm vehicle body dimensions are stable. Perform coordinate measuring machine (CMM) tests on headlights from the same recent batch. The CMM points include the tightening point of the headlights and various positioning surfaces / points. Evaluate the measurement data to ensure that the deviation of all measurement points is less than 0.5mm. Simultaneously, investigate the dimensional stability of the recent batch of vehicles. The purpose of performing the CMM tests is to ensure the dimensions of the surrounding components of the headlights are correct. Only when the dimensions are correct can the headlights be positioned correctly on the vehicle.

[0061] Install the headlights that meet the above requirements onto newly produced vehicles, assembling and tightening them according to normal procedures. Place the vehicle on the toe-in testing platform and, following the normal operating procedures, first test the low beam. Adjust the headlight width so that the displayed value is within the median value +0.9% (Note: range -1.7%~3.5%). This adjustment is done using an Allen wrench to adjust the Allen nut on the rear headlight housing (Note: some headlight manufacturers may design different structures, requiring additional specialized tools for adjustment). Then, adjust the headlight height using the same method so that the displayed value on the screen is less than -1.0%. Next, calibrate the low beam width and height of the other headlight using the same method, ensuring their values ​​are within the specified range. After low beam calibration, the toe-in testing platform will automatically perform high beam capture calculations, display the measured luminous intensity data, and determine whether the luminous intensity meets the requirements.

[0062] After the initial calibration, the vehicle was placed on a standard test track for road testing. The standard track included various road conditions such as a standard incline, uneven gravel road, winding road, washboard road, cobblestone road, and a high-speed ring road. The test drive lasted 20 minutes, with each road condition requiring 1-2 rounds of testing. The purpose of driving on bumpy roads was to allow the headlights to return to a natural mounting position on the vehicle. Under these conditions, the headlight width and height would differ slightly from the initial calibration data.

[0063] Perform the second calibration of the toe-in on the vehicle. According to the method listed in 3), place the vehicle on the toe-in detection bench again. First, observe the displayed data of the lamp width and lamp height. If the change in the lamp width and lamp height data at this time is within 0.5% compared to the data of the first calibration and is qualified, there is no need to adjust the lamp width and lamp height of the headlight again. If the change amplitude is too large, the displayed value of the lamp width needs to be adjusted to +0.9%, and the lamp height is adjusted to less than -1.0%. Then, conduct a road test again according to the above steps.

[0064] If, after the road test, when getting on the toe-in detection bench again, it is found that the change amplitude is not large, it is considered that this calibration is successful. At this time, the calibrated vehicle can be placed in other calibration channels to check the difference in lamp width and lamp height. Generally, if the difference among the three channels is within 0.5%, it is considered that the calibration is qualified.

[0065] For the two sets of calibrated headlights, use a paint pen to mark the vehicle information, calibration date, low beam height and width parameters on the lamp housing, and fix all the dimming interfaces with glue to avoid deviation of the calibration value due to the movement of the nuts during transportation or storage, and complete the production of the calibrated sample lights. Generally, the reflectors of the low beam and high beam are linked, that is, when the low beam height and width are adjusted, the high beam also follows the adjustment.

[0066] Generally, for the low beam, pay attention to the lamp height and lamp width, and for the high beam, pay attention to the light intensity. If the low beam lamp height and lamp width meet the requirements, it means that the direction of the light is not deviated and the light intensity is OK.

[0067] If there is a problem with the lamp width not being qualified at the vehicle factory after calibration, first install the sealed sample headlights on the faulty vehicle, and then conduct a vehicle installation inspection on the toe-in detection bench. If the detected value differs from the calibrated value by ±0.2%, it is considered that the vehicle body has not changed, and the vehicle lamp factory needs to analyze the reason. If the detected value is at the qualified limit or unqualified, re-perform the light calibration according to the above steps.

[0068] During the calibration process, there are usually also problems such as the inflection point of the cut-off line jumping, the inflection point of the cut-off line cannot be found, the inflection point does not move, and the high beam light intensity is unqualified (lower than the regulatory lower limit). The solutions are as follows:

[0069] 1) Inflection point jumping

[0070] Inflection point jitter: This mainly manifests as the inflection point constantly shifting back and forth, making it impossible to capture the correct low beam cutoff line inflection point, resulting in the crosshair on the toe-in screen jumping back and forth. Typically, this problem occurs because, under normal conditions, the cutoff line in low beam only has one bright spot (A), located below the HV point. If another bright spot (B) exists in other areas below the horizontal segment of the cutoff line, and this bright spot is within the scanning range of the device, the device cannot identify which is the correct bright spot during the capture process, and will repeatedly capture between A and B. In this case, optimization is generally done in two ways: For headlights, find the cause of the two bright spots and solve it by optimizing the beam pattern design. For aluminum reflectors, optimize the aluminum plating process to eliminate the unsuitable bright spot (B). On the other hand, observe the capture area of ​​the bright spot on the toe-in screen; by optimizing the device's capture range, placing the bright spot (B) outside the capture range, the cutoff line capture jitter problem can be eliminated.

[0071] 2) Unable to detect the inflection point

[0072] The headlights lack a clear inflection point; when projected onto the screen, the cutoff line in the inflection point area has no obvious inflection point, or appears as an arc, causing the system to fail to capture it correctly. During on-site four-wheel alignment and dimming, significant differences in the matching between the headlight components and the equipment can cause the inflection point to exceed or be at the dimming interface limit. Over-adjustment or directional adjustment on-site can easily lead to over-adjustment. In this situation, the first step is to optimize the headlight beam pattern to make the cutoff line clearer, while ensuring that the 15-degree or 45-degree cutoff angle is displayed more clearly.

[0073] Insufficient exposure is also a fundamental reason why the inflection point cannot be captured. Exposure is a term in photography that refers to the perceived intensity and duration of light. The brighter the object being photographed, the faster the camera's shutter speed needs to be, and the smaller the aperture needs to be. Aperture and shutter speed must work together; adjusting either one alone may not guarantee a properly exposed photograph. Conversely, if the object is dark, then a slower shutter speed and a larger aperture are necessary. Regarding headlights, for different technologies such as LED headlights and halogen bulbs, LED headlights generally require less exposure than halogen bulbs because LED headlights are generally brighter.

[0074] 3) Inflection point deadlock

[0075] When the cutoff line is adjusted to a certain position, it is found that the inflection point cannot be moved, resulting in a jam. In this case, it is necessary to check whether there is a malfunction in the manual adjustment mechanism inside the headlight, causing a failure to transmit mechanical power and preventing the inflection point from being adjusted. In this situation, the most common problem is that the adjustment screw inside the headlight is broken, stripped, or detached. There are many reasons for this. From the perspective of the vehicle body, it is necessary to investigate whether there have been any recent dimensional fluctuations in the vehicle body, which may cause the headlight width to still be unacceptable even when the headlight is adjusted to its limit. In this case, the dimensional status of the vehicle body needs to be investigated. From the perspective of the headlight itself, it is necessary to check whether there are any interference problems during the movement of the reflector bowl inside the headlight, or whether the adjustment ball joint was not fully assembled before leaving the factory, causing the manual adjustment mechanism to be unable to adjust.

[0076] 4) High beam intensity is substandard

[0077] Under current technological conditions, a single high beam is generally insufficient to fully meet road illumination requirements. Therefore, high beams are typically a combination of low and high beams. High beam illuminance generally ranges from 30,000 cd to 220,000 cd. If the high beam intensity is below 30,000 cd, it indicates a problem with the high beam intensity. In this case, the first step is to compare the beam patterns of the left and right headlights on the same vehicle. If there is a significant difference, the high beam reflector needs to be optimized to ensure complete consistency in beam patterns between the left and right headlights. If the beam patterns of the left and right headlights are consistent, then check if the deflection angle of the fault light is significantly off. If it is significantly off, optimization of the vehicle's dimensions is necessary.

[0078] As can be seen, this invention designs a calibration method for vehicle headlights on the front bezel in the final assembly workshop and establishes a complete calibration process. This verification process is the core of the research, and it is a crucial means to ensure the effectiveness of the calibration process and the reliability of the evaluation results. Besides being applicable to the calibration of headlights for current passenger vehicles, this calibration method can also be used for the calibration of headlights for commercial vehicles, thus possessing a certain degree of universality in its widespread application.

[0079] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and optimizations can be made without departing from the technical principles of the present invention, and these improvements and optimizations should also be considered within the scope of protection of the present invention.

[0080] Those skilled in the art will readily understand that the above are merely preferred embodiments of the present invention and are not intended to limit the invention. Any modifications, combinations, substitutions, improvements, etc., made within the spirit and principles of the present invention are included within the protection scope of the present invention.

Claims

1. A method of calibrating a vehicle headlamp on a toe board, characterized by: Determine the optical condition of the headlights; confirm the headlight beam parameters and stability based on the headlight beam test bench calibration; confirm the vehicle body size and stability based on the vehicle body's three-coordinate system. The Nth set of headlights for the test vehicle is calibrated using a toe-in testing platform until it passes inspection. The vehicle is then road-tested under various road conditions. After the road test, the vehicle is calibrated again using the toe-in testing platform to verify the width and height of the Nth set of headlights; N≥2. The vehicle's dimensions and stability are confirmed using a three-coordinate measuring machine (CCM) of the body. This includes mapping the headlights to fixed and positioned points on the frame, fenders, and environmental components, investigating the body dimensions of parts from the same batch, and assessing the stability of the headlight beam distribution performance. Under the premise of meeting national standards, the luminous flux of each headlight (both low and high beams) must not be less than 80% of the optical sample used in the design phase. When mapping the body using a CCM, the deviation between the measured value and the theoretical data should be less than 0.5mm. The first set of headlights that passes inspection is stored at the OEM (Original Equipment Manufacturer) to help analyze the causes of calibration problems during actual production. The second set of headlights that passes inspection is stored at the lighting factory for verification against the lighting factory's optical inspection platform.

2. The calibration method for vehicle headlights on a beam testing platform according to claim 1, characterized in that: Determining the optical condition of the headlights includes confirming the stability of the light distribution performance of the same batch of headlights and confirming the stability data of the lamp width and lamp height of the same batch of parts on the vehicle manufacturer's beam testing bench.

3. The method of claim 1, wherein: The calibration and confirmation of the headlight's toe parameters based on the toe test bench includes: calibrating the theoretical position of the headlight box capture; periodically checking the calibrated toe test bench with a standard template to ensure the correct capture position of the headlight box; among which, the stability confirmation of the toe parameters requires randomly selecting a vehicle and checking the headlight width and height data on each calibration channel to verify whether the headlight width and height data of the left and right headlights of the same vehicle are consistent on different test channels.

4. The method of claim 1, wherein: The same batch of parts showed the same trend in lamp width and lamp height variation on the front toe-in testing bench at the vehicle assembly plant.

5. The method of claim 1, wherein: When periodically inspecting the calibrated toe-in testing stations using standard templates, the difference in lamp width and lamp height between the channels of each toe-in testing station should not exceed 0.5%.

6. The method of claim 1, wherein: The corresponding differences in the width and height data of the headlights on the left and right sides of the same vehicle on different test channels shall not exceed 0.5%.

7. The method of claim 1, wherein: The acceptable range for lamp width is -1.7% to 3.5%, and the acceptable range for lamp height is less than -1.0%.

Images