Abstract
With the diversification of lighting technologies, the accurate measurement of luminous performance has become crucial for quality control and standard compliance across lighting product categories. Lumen test equipment, as the core tool for evaluating light output and optical characteristics, plays an irreplaceable role in testing energy-saving lamps, fluorescent lamps, HID lamps, cold cathode fluorescent lamps (CCFLs), and LED lamps. This paper takes the LISUN LPCE-2 (LMS-9000) High Precision Spectroradiometer Integrating Sphere System as the research object, expounds the working principle of advanced lumen test equipment, details its application in testing different types of lighting products, focuses on the multi-dimensional detection of LED quality through photoelectric color parameters, and verifies its measurement accuracy and practical value through experimental data. The research shows that the LPCE-2 system can meet international standards such as CIE 177 and IES LM-79-19, providing reliable technical support for the lighting industry’s quality assurance.
1. Introduction
Lighting products are widely used in industrial production, public infrastructure, and household environments, and their luminous performance directly affects energy efficiency, lighting quality, and user experience. Lumen test equipment, which specializes in measuring key parameters such as luminous flux, luminous efficiency, and chromaticity, has become an essential guarantee for ensuring product performance consistency and compliance with regulatory requirements.
Traditional lumen measurement tools often have limitations such as low accuracy, poor compatibility, and single test functions, which are difficult to adapt to the simultaneous testing needs of multiple lighting technologies. In contrast, modern integrated lumen test equipment represented by spectroradiometer integrating sphere systems integrates optoelectronic detection, spectral analysis, and data processing, realizing high-precision and multi-parameter measurement of various light sources.
The LISUN LPCE-2 (LMS-9000) High Precision Spectroradiometer Integrating Sphere System is a typical representative of advanced lumen test equipment. It adopts one-piece molding integrating sphere technology and high-performance CCD spectroradiometer, which can cover the testing needs of energy-saving lamps, fluorescent lamps, HID lamps (including high-pressure sodium lamps and high-pressure mercury lamps), CCFLs, and LED lamps. This paper systematically analyzes the application value of this lumen test equipment in the lighting industry.
2. Working Principle and Technical Advantages of LISUN LPCE-2 Lumen Test Equipment
2.1 Core Working Principle
The LPCE-2 system, as a professional lumen test equipment, realizes comprehensive parameter measurement based on the combination of integrating sphere technology and spectral radiometry. The integrating sphere, the core component of the system, is a hollow sphere with an inner wall coated with high-reflectivity PTFE material (reflectivity > 98%). When the light source under test emits light into the sphere, it undergoes multiple diffuse reflections on the inner wall, forming a uniform light field. The spectroradiometer collects the light signal through the optical fiber, converts it into an electrical signal, and calculates key parameters such as luminous flux, chromaticity coordinates, and correlated color temperature (CCT) through professional software based on spectral power distribution data.
The system integrates electrical parameter measurement modules, which can simultaneously collect voltage, current, and power data while measuring optical parameters, realizing the integrated detection of photoelectric performance. For LED long-term reliability testing, the system can also track the change trend of parameters such as luminous flux maintenance rate and CCT over time in accordance with the LM-80 standard.
2.2 Key Technical Advantages
Compared with traditional lumen test equipment, the LPCE-2 system has significant technical advantages:
• High-precision measurement capability: Equipped with LMS-9000C high-precision CCD spectroradiometer, the wavelength accuracy reaches ±0.3nm, and the chromaticity coordinate accuracy is ±0.002 under standard A light source. The luminous flux measurement range covers 0.01-200,000lm, and the photometric linearity error is only ±0.5%.
• Superior integrating sphere design: The one-piece molding integrating sphere is more spherical than the traditional spliced sphere, which effectively reduces measurement errors caused by uneven light field distribution and improves test repeatability.
• Comprehensive standard compliance: The test results fully meet international and national standards such as CIE 177, CIE-84, ANSI-C78.377, GB/T 24824, and IES LM-79-24, ensuring the authority of measurement data for product certification and market access.
• Strong compatibility: It can test various light sources including AC-driven energy-saving lamps and HID lamps, and DC-driven LED modules, with optional 0.3m and 1.5m integrating spheres to adapt to different sizes of samples.
• Intelligent operation and analysis: The system supports Windows 7-11 operating systems, with Chinese and English software interfaces, and can automatically generate PDF format LM-79 test reports and Excel format light decay test reports, improving testing efficiency.
LPCE-2(LMS-9000)High Precision Spectroradiometer Integrated Sphere System
3. Application of LISUN LPCE-2 Lumen Test Equipment in Multi-Type Lighting Products
The LPCE-2 lumen test equipment, with its strong compatibility and high precision, can realize targeted testing of different lighting products. Table 1 shows the key test parameters and technical requirements for various light sources.
Table 1: Key Test Parameters of Different Lighting Products by LPCE-2 Lumen Test Equipment
Lighting Type
Key Test Parameters
Test Standards Compliance
Special Requirements
Energy-saving Lamp
Luminous flux, luminous efficiency, power factor, CCT, color rendering index (Ra)
GB/T 19044-2013, IEC 60969
Need AC power supply matching rated voltage, preheating time ≥ 5min
Fluorescent Lamp
Luminous flux, luminous efficacy, color tolerance, Ra, power consumption
CIE 84, GB/T 10682-2022
Test after 100h aging to stabilize luminous performance
High-pressure Sodium Lamp
Luminous flux, CCT (1800-2200K), Ra (20-30), luminous efficiency
IEC 60662, GB/T 13259-2019
High-power test (up to 1000W), need to monitor ballast matching performance
High-pressure Mercury Lamp
Luminous flux, UV radiation ratio, Ra (20-40), power factor
GB/T 7453-2017, IEC 60188
Need UV filtering detection module, test ambient temperature 25±2℃
CCFL
Luminous flux, color purity, peak wavelength, startup voltage
JIS C 8113, GB/T 21542-2008
Low current drive, focus on luminous uniformity measurement
LED Lamp/Module
Luminous flux, luminous efficiency, CCT, Ra, color coordinates (x,y), WPE, EEI
LM-79-19, GB/T 24824-2021
Combined with LM-80 test, track luminous flux maintenance rate over 6000h
3.1 Testing of Traditional Gas Discharge Lamps
Traditional gas discharge lamps such as fluorescent lamps and HID lamps rely on gas ionization to emit light, and their luminous performance is greatly affected by factors such as discharge voltage and ambient temperature. The LPCE-2 lumen test equipment solves the key technical problems in their testing through the following designs:
• For fluorescent lamps, the system uses an AC variable frequency power supply (LSP-500VARC) to simulate the actual working voltage, and measures the luminous flux and color temperature after the lamp is stabilized for 10 minutes. The test data shows that the deviation between the measured value and the standard light source is less than ±1.5%.
• For high-pressure sodium lamps, which have high power and strong directional light emission, the one-piece 1.5m integrating sphere of the LPCE-2 system can fully collect the scattered light, and the equipped high-sensitivity detector can accurately measure the low-color-rendering-index light source, with Ra measurement accuracy reaching ±(0.3%rd±0.3).
3.2 Testing of CCFLs
CCFLs are widely used in backlighting fields such as liquid crystal displays, with the characteristics of narrow light-emitting area and low luminous flux. The LPCE-2 system uses a 0.3m small-diameter integrating sphere and a high-resolution CCD spectroradiometer (scanning interval ±0.1nm) to accurately capture the spectral characteristics of CCFLs. In the test of a 12-inch CCFL backlight module, the system successfully measured the peak wavelength (455nm) and half-bandwidth (20nm), and the color purity reached 92%, which was consistent with the design parameters.
3.3 Focus on LED Quality Testing: Photoelectric Color Parameter Detection
LED lamps, as the mainstream of current lighting products, have their quality directly determined by photoelectric color parameters. The LPCE-2 lumen test equipment realizes comprehensive evaluation of LED quality through multi-dimensional parameter detection:
3.3.1 Luminous Performance Parameters
Luminous flux and luminous efficiency are the core indicators of LED energy-saving performance. The LPCE-2 system uses the spectral method to measure luminous flux, which avoids the error caused by the mismatch between the traditional photometric method and the LED spectrum. Taking a 10W LED downlight as an example, the system measured a luminous flux of 850lm and a luminous efficiency of 85lm/W, which met the level 1 energy efficiency standard specified in GB 38450-2021.
3.3.2 Chromaticity Parameters
Chromaticity parameters including CCT, color coordinates, and Ra directly affect lighting comfort. The system can measure CCT in the range of 1500K-100,000K with an accuracy of ±0.3%. For warm white LED lamps (nominal CCT 3000K), the measured CCT is 2985K, and the color coordinate deviation (Δx, Δy) is 0.001, which is within the ANSI-C78.377 standard range. The Ra measurement shows that the Ra of the sample is 82, which is suitable for indoor lighting scenarios.
3.3.3 Electrical Parameters
The electrical performance of LEDs is related to their service life and safety. The LPCE-2 system is equipped with an LS2050C digital electrical parameter measuring instrument, which can synchronously measure voltage, current, power, and power factor. The test of a 50W LED street lamp shows that its power factor is 0.95, the harmonic distortion is less than 10%, and the electrical performance is stable.
3.3.4 Long-term Reliability Parameters
According to the IES LM-80 standard, the LPCE-2 system can conduct 6000-hour light decay tests on LED modules. The test data shows that the luminous flux maintenance rate of a high-quality LED sample is 93% after 6000 hours, while the inferior sample drops to 75%, effectively distinguishing product quality levels.
4. Experimental Verification of Measurement Accuracy
To verify the measurement accuracy of the LPCE-2 lumen test equipment, a comparative experiment was conducted using standard light sources and representative samples of various lighting products. The experimental environment was controlled at 25±1℃, and the relative humidity was 50±5%.
Table 2: Measurement Accuracy Verification of LPCE-2 Lumen Test Equipment
Test Object
Parameter
Standard Value
LPCE-2 Measured Value
Relative Error
Compliance with Standard
Standard A Light Source
Luminous Flux
1000lm
1004lm
+0.4%
CIE 84 (≤±1%)
CCT
2856K
2863K
+0.24%
IEC 60359 (≤±0.5%)
18W Energy-saving Lamp
Luminous Efficiency
65lm/W
64.7lm/W
-0.46%
GB/T 19044-2013
400W High-pressure Sodium Lamp
Ra
25
24.8
-0.8%
GB/T 13259-2019
5W LED Module
Color Coordinate (x)
0.3450
0.3458
+0.23%
ANSI-C78.377
Color Coordinate (y)
0.3520
0.3525
+0.14%
As shown in Table 2, the relative error of the LPCE-2 lumen test equipment in measuring various parameters is less than 1%, which fully meets the requirements of relevant international and national standards. The high accuracy is attributed to its one-piece integrating sphere design and high-performance CCD detector, which effectively reduces the influence of stray light ( https://www.lisungroup.com/news/technology-news/application-of-lumen-test-equipment-in-multi-type-lighting-products-a-case-study-of-lisun-lpce-2-high-precision-spectroradiometer-integrating-sphere-system.html
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