China Inspection and Quarantine, Factory Inspection, Certification, Testing, and Inspection | Automobile Headlamp Inspection and Testing Standards and Methods

Headlamp testing is a crucial component of vehicle safety performance inspections . Its diagnostic core focuses on two key parameters: luminous intensity and beam position. Insufficient headlamp intensity or a skewed beam position can lead to blurred vision and glare for oncoming drivers at night, seriously impacting driving safety. Therefore, regular inspection and calibration of headlamp intensity and position are essential. Previously shared content introduced basic inspection methods using the screen method and a headlamp calibration instrument. This article will focus on the inspection standards and instrument testing methods for headlamp luminous intensity, incorporating common quality control points from third- party and factory inspections .

2. Headlamp Luminous Intensity Standards and Instrument Testing Methods

(1) Inspection and testing standards for headlamp luminous intensity

According to national standards GB7258-2017, "Technical Requirements for Motor Vehicle Operation Safety," stipulates that the luminous intensity of the high-beam headlights of motor vehicles must meet the requirements specified in the table (see Table 2). During inspection , the vehicle's power system must be in a charging state to ensure the accuracy of the test results. This standard serves as the core basis for evaluating headlight compliance during product and factory inspections.

Table 2 Luminous intensity requirements for high beam of headlamp (content omitted, users are required to provide specific values)

Note: For motor vehicles with a four-lamp system, if two of the symmetrical lamps meet the requirements of a two-lamp system, they are considered qualified.

(2) Headlamp calibration instrument detects luminous intensity and optical axis deflection

A headlamp calibrator is a device specifically designed to test the luminous intensity and optical axis deflection of headlamps. It is typically placed at a certain distance in front of the vehicle. This device is widely used in vehicle manufacturing inspections , factory inspections , and regular safety inspections .

1. Testing principle of headlamp calibration instrument

Different types of headlamp calibrators are all designed based on photocell sensors, which can convert the received light energy into a current signal. By analyzing the magnitude and ratio of this current, they can measure the luminous intensity and beam deflection of the headlamp.

(1) Detection principle of luminous intensity

The luminous intensity detection circuit consists of a photometer, a variable resistor, and a photocell (see Figure 3). When the headlight shines on the photocell at a specified distance, the photocell generates a current corresponding to the intensity of the light received, driving the photometer pointer to indicate the luminous intensity value. This result is used directly to determine whether the headlamp meets national standards and is a key performance metric in the inspection report.

1-photometer; 2-variable resistor; 3-photocell

(2) Principle of optical axis deflection detection

The optical axis deflection detection circuit typically consists of two pairs of photocells, one above and one below, connected to a deflection indicator (see Figure 4). If the beam deflects, a current difference is generated between the photocells, causing the indicator needle to swing, thereby determining the direction and amount of deflection.

1-left and right deflection indicator; 2-photocell; 3-up and down deflection indicator

• When the optical axis is not deflected : the pointers of the up and down and left and right deflection indicators all point to zero (see Figure 5), and the light beam is centered.

• When the optical axis is deflected : the pointer of the indicator is offset, for example, deflected to the "downward" or "left" direction (see Figure 6), and calibration is required accordingly.

The adjustment mechanism can realign the beam, returning the deflection indicator to zero. This adjustment represents the optical axis deflection. Simultaneously, the sum of the currents from the four photocells reflects the headlamp's luminous intensity, completing two key tests simultaneously.

3. Headlamp Inspection Practices in Third-Party Inspection and Factory Inspection

During the inspection of auto parts and vehicle manufacturing , headlamp inspection usually covers the following aspects:

• Sampling inspection : Sampling is carried out according to AQL standards to ensure sample representativeness;

• Performance test : Use a headlamp calibration instrument to test the luminous intensity and optical axis deflection item by item, and check whether it is qualified by comparing with GB7258;

• Functional and safety inspection : including additional items such as stability under voltage fluctuations, sealing, and vibration resistance;

• Reports and Records : Inspectors are required to record each test result in detail, take relevant photos, and issue a formal inspection report as the basis for acceptance or rejection.

Professional third-party inspection companies can also provide pre-production factory assessments, production line spot checks (IPC), and final random inspections (FRI) to ensure that headlamps meet safety and technical standards throughout the entire process from production to delivery.

IV. Summary

The luminous intensity and beam position of headlights are directly related to driving safety. Inspections must strictly adhere to national standards and utilize specialized equipment, such as headlight calibration instruments, for scientific measurement. Within the automotive supply chain, a systematic product and factory inspection mechanism effectively controls product quality, reduces safety risks, and provides reliable protection for manufacturers and consumers.