High/Low Temperature & Humidity Test Chamber Analysis in China Market

High/Low temperature & humidity test chamber is used to simulate a actual temperature and humidity environment which it may caused any influence for surrounding objects，due to electronic products widely application in various occasions, in order to design better product which meet relevant environmental standards, the temperature and humidity test has become an necessary test items, and high/low temperature and humidity test chamber widely used in many different industries such as aerospace product, electronic instrumentation, materials, electronic products and various electronic components, this environmental test chamber used to checking working performance of DUT in high temperature, low temperature or hot and humid environment. This article focuses on discussion environmental climatic chamber application on the LED lighting industry application.
Lisun Electronics (Shanghai) Co., Ltd is one of best LED lighting test equipment supplier, our products involved photometric, colorimetric and electrical measurement, EMC & EMI test, electrical safety test and environmental test, our product line also included temperature & humidity test chamber. Our environmental climatic chamber is special design and manufacture based on many years experience and professional knowledge in the LED lighting industry, our products key technical index as following:
1、 Chamber Structure:
1) The chamber is produced by SUS304 Steel, the temperature keeping material is produced by Polyurethane hard foam and ultra-fine fiber glass, the doorframe heat insulated by Double high temperature aging silicone rubber door sealing strip.
2) Humidification system and circuit board system was designed separately which avoid leakage caused by humidification pipeline failure, and improve higher safety; the chamber built-in water purification device and automatic water protection.
3) With big glass window and inside built-in lighting luminaire to make easy observation, the left side of chamber has built-in φ50mm hole port, it can connect outside power supply cable or signal cable.

2、 Programmable PLC touch screen:
1) The temperature controller is used by Korean TEMI display in English/Chinese and German Siemens PLC(See below Figure 1), the temperature sensor is platinum PT100 Ohms/MV resistor.

Figure 1

2) The TEMI display can be English or Chinese and show test curve, it come with maximum 120 sets of program 12000 segments 999 cycle step capacity, each segment test time can be set maximum 99 hours 59 minutes.
3) After set up test data and condition, the screen of display will be locked to avoid artificial touch and cause stop working, and it can communicate to PC via RS-232/RS-485 to monitor test process and implementation of automatic switching machine function. Besides, it combined automatic calculate function, the temperature and humidity conditions can be amended immediately to make sure temperature and humidity control more accurate and stable.
3、 Heating / Humidification Circulation System:
1) The compressor imported from France TECUMSEH brand(See below Figure 2) which can allow you get after sales support from many countries.

Figure 2

2) The heating system is full separately system which produced by Nickel chromium alloy electric heating type heater; the cold system is applied by fully enclosed fan cooled single-stage and cascade refrigeration mode. Application multi-wing blower strong air circulation design to avoid any dead ends, the test area can be evenly distributed temperature and humidity. Wind circulation cycle design, wind pressure, wind speed are meet test standards, the temperature and humidity stabilization time very quick after opened the door.

Compared with similar products in the market, our environmental climatic test chamber has following advantages:
1、 Many supplier claim theirs product’s inside working temperature can be reach to -20°C~+150°C or +150°C or -60°C~+150°C, but acoording to our acutal survey, the temperature range they marked was non-load temperature test condition, that means if DUT don’t working, then it can be reach this temperature but after EUT start working, the actualy temperature can’t reach they said. For example, when we put a 100w~150w tested luminaires inside of chamber, after light it up, the inside actual temperature only have -50°C(Setted test temperature is -60°C) or -30°C(Setted test temperature is -40°C). Lisun products can fully meet -20°C~+150°C or -40°C~+150°C or -60°C~+150°C test temperature range(Under tested lamp fully working status), this point can indicated that there have big difference between we used compressor, refrigerants and heating devices and our competitor used, our temperature climatic chamber used France TECUMSEH brand compressor and 6P capacity refrigerants. The below is GDJS-015A model testing pictures(See below Figure 3 and Figure 4):

Figure 3: 70°C test temperature and 70% test humidity (Tested luminaires full working status)

Figure 4: Set the lowest -20°C test temperature and PLC touch screen showing(Tested luminaire full working status)

2、 Our product adopted with Finland brand electronic humidity sensor, but as we know our competitor used dry ball device, the advantage of electronic humidity sensor is no need to do maintain work; but inside humidity sensor of dry ball not only have big accuracy influence by environmental, and it also easy get problem, the important is the user can’t adjust water supply and repair by themselves once it broken, this further cause instrument can’t normal working.(See below Figure 5):

Figure 5: The RED color part is Electronic Humidity Sensor

3、 Our product equipped a water purification device, customer can use a water pipe connect it to provide water supply directly, meantime, it also equipped a linkage solenoid valve which control by PLC control panel to prevent over water supply and can to do automatic to do water supply. But our competitor usually use a water tank which often lack of water and caused testing terminated. (See below Figure 6):

Figure 6: The RED color part is Linkage Solenoid Valve; The BLUE color parts is Water Purification Device(One is as backup).

4、 Our temperature climatic chamber’s key electrical connector parts adopted with famous brand AC contactor and solid state relays from Schneider and Omron brands. (See below Figure 7):

Figure 7: Schneider and Omron brands AC contactor and solid state relays

5、 For some customer need to do high temperature and high humidity test at same time(For example: both 70°C temperature and 70% humidity test), besides we provide standad rubber stopper, we also will provide extra high pressure release tube, if without pressure release tube, it may cause both temperature and humidity can’t reach up to setted value and further influence final test result. (See below Figure 8):

Figure 8: The RED color part is Pressure Release Tube

Based on above new design and technology application, Lisun high/low temperature and humidity test chamber has sold to worldwide and accepted by many famous company and ISO/IEC 17025 accreditation test laboratory, our products can fully meet all kind of environmental test requirement.

Application for IEC 60529（GB4208-1993）IP Protection Grade

IEC 60529 IP code is a coding system to indicate the degrees of protection provided by an enclosure against access to hazardous parts, ingress of solid foreign objects, ingress of water and to give additional information in connection with such protection IP code includes 4 digits, like IP23CH. IP short for ingress protection; numeral 2 stands for first characteristics and can be instead by numerals 0 to 6 or letter X (not requires to specified), it indicates enclosure against ingress of solid foreign; Numeral 3 standards for second characteristics and can be instead by numerals 0 to 8 or letter X (not requires to specified), it indicates enclosure against ingress of water with harmful effects. Letter C is additional letter, indicates enclosures access to hazardous parts, can be instead by letters A, B, C and D, but this characteristic can be ignored; Letter H is supplementary letter, can be instead by letters H, M, S and W, but this characteristic can be ignored. In this article, we just discuss the first and second characteristics.

The first characteristic can mark with numerals 0 to 6. We temporally ignore the second characteristic, additional letter and supplementary letter, i.e. IP0X to IP6X. According to IEC60529, it describes as: IP0X——non protected; IP1X——≥50mm diameter; IP2X——≥12.5mm diameter; IP3X——≥2.5mm diameter; IP4X——＞1.0mm diameter; IP5X——dust protected; IP6X——dust tight.

There are many standards refer to IEC60529 regarding dustproof test, like IEC60598 luminaires general requirements and tests, clause 2.3 mentioned to classified the luminaire according to degree of protection against ingress of dust, solid objects and moisture; GB2423.37-89 electric and electronic products basic environmental testing procedure mentioned that sand and dust test method; GB/T4942.2-93 protection grade for low voltage device shell; GB7000.1-1996 and GB7001-1986 luminaire general requirements and test standard mentioned that the luminaire only need to do the test for IP5X and IP6X.

The second characteristic can mark with numeral 0 to 8. We temporally ignore the first characteristic, additional letter and supplementary letter, i.e. IPX1 to IPX8. According to IEC60529, it describes as: IPX0 non protected; IPX1——vertically dripping; IPX2——dripping (15°tilted); IPX3——spraying; IPX4——splashing; IPX5——jetting; IPX6——powerful jetting; IPX7——temporary immersion; IPX8——continuous immersion. The applied water requests clean water. According to the standard, drip box is for IPX1 and IPX2 test; Oscillating tube or spray nozzle is for IPX3 and IPX4 test, the semi-diameter of oscillating tube has 8 solutions for optional according to the size of the sample, the minimum is 200mm, the maximum is 1600mm, and increase step is 200mm. But quantity of the holes is difference for each grade. For example, there are 8 holes in semi-diameter 200mm tube for IPX3, but for IPX4, there are 12 holes in semi-diameter 200mm tube. Water jet hose nozzle is for IPX5 and IPX6 test, but difference grade, the inner diameter of nozzle is different, the inner diameter of nozzle is 6.3mm for IPX5, and 12.5mm is for IPX6, the distance from nozzle to enclosure is 2.5m to 3m. Immersion tank is for IPX7 and IP8 test, the test time is 30min for IPX7.

There are also many standards refer to IEC60529 regarding dustproof test, like IEC60598 luminaires general requirements and tests mentioned to classify the luminaire according to the degree of protection against ingress of water; IEC60335 house holding and similar electrical appliance general requirements and IEC60034-5:2000 degrees of protection provided by the integral design of rotating electrical machines mentioned the waterproof test.

In practice, it is a big problem for electronic equipments, luminaire, and house holding manufactures to find the right products to do the waterproof and dustproof test. Lisun Group developed the SC-X series dustproof test chamber and JL-X series waterproof test equipment according to IEC60529. SC-X dustproof test chamber is for IPX5 and IPX6 test, there are several models for optional according to the sample size.JL-X is for IPX1 to IPX8 test, there are four equipments for optional, JL-12 drip box is for IPX1 and IPX2 test; JL-34 swing pipe water spray test equipment is or IPX3 and IPX4 test; JL-56 waterproof jet test device is for IPX5 and IPX6 test; JL-78 immersion tank is for IPX7 and IPX8 test.

Lisun Group was found on 2003 year, there are sales and support agencies both in Hong Kong and Shanghai. Lisun Group is engaged in developing the LED and CFL test equipments, our main equipments includes EMC test equipments, safety test equipments, environment test equipments, spectroradiometer, integrating sphere, goniophotoemter and etc. Our equipments are accepted in the world wide, and we worked with many world famous companies, like GE, Philips, Sharp, Osram, Sony and etc

Glow wire test

Glow wire test is to test the stability of electrical and electronic products during working. And the hot wire itself is the resistance wire ring with fixed size. When doing test, the wire ring should be heated up to the specified temperature by electricity, so that the time when the top of the wire reached the sample can meet the time standard required, then observe and measure its state. The test range depends on the specific test procedures.

When do the test for the determination of the burning of hot wire (GWFI) in a solid electrical insulation material or other solid materials test sample, there is a detailed requirement for the hot wire test method in standard GB/T 5169. Test results can be used for relative comparison of the performance of the above various materials, namely, the ability of the flame extinguished when remove the electricity heated hot wire; and the ability to not produce burning or glowing particles for the beneath bedding layers and packaging paper of the sample. This test method is not suitable for testing the flammability of the whole equipment, because the insulation system, the structure of the combustible components and the arrangement and heat transfer of metal or nonmetal parts, the material has a great influence on the material used. In addition, this test method is not suitable for determining the performance of fire prevention and the risk of fire.

ISO/IEC 13943：2000 gives the following terms and definitions:

（GWFI）Glow-wire flammability index

During three times continuous tests, the highest test temperature of one test sample with the prescribed thickness satisfies one of the following conditions:

1. A) After removing of the hot wire test, the flame and glow wire extinguished in 30s, and the packaging paper placed beneath the test sample won’t burning out.
2. B) The test sample won’t burning out..

（GWIT）glow-wire ignition temperature

The test sample is not caused by a test sample of a continuous three test, the highest temperature 25K (900C~960C) of the top of the burning wire is the highest temperature (30K).

Comparing the temperature of the three consecutive tests won’t be caused by the provisions of the thickness of the test sample from the burning of the top of the hot wire 25K(900-960C), the temperature is 30K higher.

Test severity levels:

Observation and measurement

During the application of the hot wire and in the subsequent 30s, test personnel should observe the sample and the packaging paper placed in the bottom, and make the following record:

1. A) The burning time from the top of hot wire to the test sample or to the bed layer under the test sample.
2. B) The burning time from the top of the hot wire to the extinguishing, the flame may extinguished in or after the application.

Evaluation of test results

If the test sample is not ignited or satisfy one of the following two conditions, then chose a relative low test temperature in Table 1, and repeat test with a new test sample

If it meets the above two conditions at the same time, then chose a relative low test temperature in Table 1, and repeat test with a new test sample. The test should be continued twice when the test sample meets the highest test temperature in condition a) and b).

The GWFI need to be determined is the temperature meets the maximum test temperature in condition a) and b) during three consecutive trials.

When the material is measured at the highest temperature in Table 1, the GWFI test program is not required to run GWIT. The corresponding thickness of the material will be 960C GWFI.

GWFI: should be recorded as follows

For example, the test sample of the 3mm thickness is 850C, the record is: 850/3.0 GWFI.

To meet the requirements of the above, Lisun developed ZRS-3H Glow Wire Test Apparatus, it is specially designed and produced according to the standard measurement requirements of IEC60695-2-10~IEC60695-2-13(GB/T5169.10-2006~GB/T5169.13-2006), basic testing methods of glow wire, glow wire testing apparatus, general trail program, UL746A, IEC829, GB5169, DIN695,VDE0471 or ASTM-3874-2004 and so on. Lisun Electronic (Shanghai) office is committed to the development and after-sales maintenance of lighting instrument, EMI / EMC testing system and safety testing instruments in the domestic and global market. The full range of products of Lisun are in strict accordance with the quality management and control of ISO9001:2008 requirements for R & D and production; Lisun is also the member unit of global lighting CIE association, all products are according to CIE requirements; in addition, all products of Lisun are certified by CE and get the qualification of the EU.

The Status of Integrating Sphere in China Market

IES LM-79-08 “Electrical and Photometric Measurement of Solid-State Lighting Products” as the exclusive international standard for measuring the total luminous flux, electrical power, luminous intensity distribution and correlated color temperature (CCT), color rendering index (CRI) and other colorimetric parameters of solid-state lighting products (SSL), it highlights the total luminous flux of SSL products should be measured with the integrating sphere system or goniophotometer. So the integrating sphere, as one of the main measuring instruments of SSL products, it can reduce and eliminate the measurement error caused by the difference of light shape, divergence angle and responsivity of different positions on the detector. Its design and manufacturing process is especially important and will directly affect the accuracy of test results.

Here we take a look at the current status of the production of integrating sphere technology in China market.

The Status of Integrating Sphere in China Market

Figure 1 The Old model Integrating Sphere

At present, there are still many suppliers in China using the old model integrating sphere. This kind of hemisphere is made of six steel sheets, and then using a clamp to combine the two hemispheres. The bottom is supported by an elastic adjustable foot to fix whole integrating sphere. However, there are many defects in this Splicing sphere, such as the structure is not strong, and it is easy to damaged and fell off during the long-distance transportation, and the ball is not round, which will definitely cause errors to the measurement results. We can see the difference in its shape when measuring with a standard round ruler, please refer to Figure 2:

The Status of Integrating Sphere in China Market

Figure 2 Using a standard round ruler to measure the old model sphere

Lisun developed a new type of integrating sphere (IS- *MA), its hemisphere is made of A Molding Technology which technical requirements are very high. So the test results are very accurate, and its appearance is elegant, also the roundness is very good, please see the following figures.

The Status of Integrating Sphere in China Market

Figure 3 Lisun New Design Integrating Sphere

The Status of Integrating Sphere in China Market

Figure 4 Using a standard round ruler to measure Lisun New Design Integrating Sphere

The new design integral sphere uses a fixed caster to replace the conventional fixed foot. And people can easily move the integrating sphere. Moreover, the sphere can be dismantled and assembled in half. The width of the hemisphere is about 1/2 of the whole sphere, which is very suitable for the transportation of spheres, especially for the small door size of offices or laboratories. In addition, this integrating sphere has equipped with a detachable test hold base, it can install different kinds of jigs according to the different types of lamp, which is very simple and convenient. The hold base can bear maximum weight 20 kg, It can be easy to install various lamps such as E27, E40, LED luminaires and so on. If you want to install other lamps, you just need to change the corresponding jigs. The hold base can be mounted on the bottom of the integrating sphere or mounted on the top of the integrating sphere. The position can be changed according to light sources. Please refer to the figure below.

The Status of Integrating Sphere in China Market

Now, let’s take a look at the comparison between these two kinds of integrating spheres.

The Status of Integrating Sphere in China Market

Old Model Sphere Lisun New Design Integrating Sphere

The Status of Integrating Sphere in China Market

Old Model Sphere Lisun New Design Integrating Sphere

The Status of Integrating Sphere in China Market

Old Model Sphere Lisun New Design Integrating Sphere

Please feel free to contact us if you need more info or quotations: Sales@Lisungroup.com

How to choose the right goniophotometer according to the standard LM-79 and EN13032-1？

How to choose the right goniophotometer according to the standard LM-79 and EN13032-1？

There is a wide range of goniophotometers on sale in the market, including central rotation type, rotation mirror type, double mirror type and so on. How to choose the corresponding goniophotometers for the tested lamps becomes the most important problem for the users. This article makes a brief introduction to this knowledge based on LM-79 and EN 13032-1.

A-α B-β and C-γ Co-ordinate System

According to EN13032-1, no matter what kind of goniophotometers is used, the main measurement plane must be based on the picture below when measuring the light distribution performance of the luminaire

1.    First axis
2.    Second axis
3.    Third axis
4.    Photometric Center

On this basis, the main coordinate systems used in the past are the following three:
1.    A-α：This coordinate system has not been used any more when testing conventional lamps and is only used to measure special lamps such as traffic, channel lights and indicator lights. Do not introduce it here. (Lisun LSG-1950 Goniophotometer for automotive and traffic signal lamps is specially designed according to this coordinate system)
2.    B-β：It is still used, but mainly for testing spot lights.
3.    C-γ：At present, it is recommended by the international standard which can guarantee the accuracy of the test at utmost.

B-β coordinate system
The schematic diagram is as follows：

1.    First axis
2.    Pole axis
3.    Third axis
4.    B Panel

• The first axis of the luminaire passes through the photometric center and is perpendicular to the B plane, which is also the main light emitting surface of the luminaire. The luminaire is measured by a photometric probe when revolving around the third axis and the polar axis.
• For non flood light, if you use the B-β test, the reference axis of the lamp need be taken as the third axis above, while the main light emitting surface is facing the probe, which means the probe is located on the first axis.

C-γ coordinate system
The schematic diagram is as follows：

1.    First axis (Pole axis)
2.    Second axis
3.    Third axis
4.    C panel

• The polar axis rotates on the C plane, while the C plane rotates around the polar axis. The photometric probe is located on the third axis
• When the lamp is still, the light emitting surface of the luminaire must be facing the probe, i.e., both of them are located on the third axis. If they are inconsistent and inclined, it need to be explained.
• The test results of C and B coordinate system can be calculated and swap. Lisun’s LSG-1800B/LSG-5000/LSG-2000 provides two special test fixtures and can also direct conversion in software.

LISUN Goniophotometers Detailed Characteristics

The Goniophotometer is based on these two coordinate systems to carry the test, especially the use of C- gamma coordinate system products occupy most of the market. Based on this coordinate system, a variety of Goniophotometer with different working principles are derived.

1. Goniophotometer with Moving Mirror and Moving detector

LSG-5000 Moving Detector Goniophotometer fully meets LM-79 Clause 9.3.1 request. The tested lamp will keep burning position and be fixed. Near field detector, the lamp and the mirror are in the same line. During the test, the near field detector and the mirror will circle around the lamp, and the far field detector will rotate synchronously with the mirror.

• The instrument needs to be used in the darkroom, and the darkroom is equipped with diaphragms and light traps to reduce stray light and ensure the accuracy of the test
• According to the LM-79 standard, the color distribution test should be carried out while the photometric test is carried out. The user can select the color detector at the time of purchase, and test the color directly.

2. Goniophotometer with Moving Mirror

LSG-2000 Goniophotometer with Moving Mirror can test luminaries rotating in the prescribed burning position and around the vertical axle and a reflecting mirror rotates around the horizontal axle, meanwhile, a synchronous axle will rotate toward the opposite direction synchronously, so the luminous intensity has no change. Using the C-γ coordinate system to carry the test and comparing with the Moving Mirror and Detector Goniophotometer above, the difference is the lamp will rotate with the movement of the mirror synchronously and lower accuracy than Moving Mirror and Detector Goniophotometer.

• Meets the test requirements of C-γof LM-79 and EN13032-1 standards and has higher accuracy for LED lamp.
• Meets the test principle of CIE-70-1987 7.3 for goniophotometer.
• Needs to be used in the darkroom, and the darkroom is equipped with diaphragms and light traps to reduce stray light and ensure the accuracy of the test
• According to the LM-79 standard, the color distribution test should be carried out while the photometric test is carried out. The user can select the color detector at the time of purchase, and test the color directly.

3. Central Rotation Goniophotometer (horizontal)

LSG-1800B high precision ratation luminaire goniophotometer system carries out measuring methods of fixed location and rotating luminaires. The measured luminaire is installed on the rotating supported, the center of which is in line with the rotating supporter center. The fixed photometry detector is testing the luminous intensity in various horizontal directions, while the light source rotating. The mechanical equipment allows turning the tested luminaires around a vertical axis and a horizontal axis. When tested luminaires turn around horizontal axis, the detector which is at the same level with rotating table will measure the intensity of each direction at this surface. When rotating with vertical axis, the detector will measure the intensity at the vertical surface.

This goniophotometer system has fast test speed, low requirement of darkroom, simple installation and maintenance, and high test accuracy for LED lamp. But for parts of the gas discharge lamp (such as fluorescent lamps, halogen lamps, etc.) because the lamp cannot be fixed in the lamp position, the accuracy will be lower than the two goniophotometer above. It is usually used to carry the factory inspection.

• Meets the test requirements of C-γof LM-79 and EN13032-1 standards and has higher accuracy for LED lamp.
• Needs to be used in the darkroom, and the darkroom is equipped with diaphragms and light traps to reduce stray light and ensure the accuracy of the test
• According to the LM-79 standard, the color distribution test should be carried out while the photometric test is carried out. The user can select the color detector at the time of purchase, and test the color directly.

3. Goniophotometer with color detector

There are two different ways to test the colorimetric parameters according to the descriptions of LM-79 part 12:
1.    Get the average value of the colorimetric parameters of the sample in space directly via measuring by an integrating spherespectroradiometer system.
2.    Get the colorimetric parameters of each angle in space via adding a color detector to the goniophotometer system in the darkroom. We call the whole system “Goniospectroradiometer”. When second measuring methods are used, the interval and range of the detector scan should be consistent with the photometric measurements. The specific parameters can be seen in LM-79 9.3.3.

LSG-5000CCD moving detector goniospectroradiometer. The color detector is together with the near field photo detector.

LSG-2000CCD goniospectroradiometer with ratationg mirror. The color detector is in the dark room.

LSG-1800BCCD high precision rotation luminaire goniospectroradiometer. The color detector is in the dark room.

• The principle of these type goniophotometers is adding a color detector and a spectroradiometer in the darkroom to the coaxial axis of the photometric detector to carry the test.
• IF the color detector of LSG-5000CCD is installed in the near field, it can carry the test directly.

Conclusions

From the above, we can conclude that when selecting the goniophotometer, the following principles need to be followed:
1.    In addition to automobile lights and traffic lights, try to choose the C-γ coordinate system goniophotometer. ( LSG-1800B/LSG-2000/LSG-5000 can carry the test of C-γ and B-β )
2.    To get higher test accuracy, try to choose the rotation mirror and rotation detector goniophotometer or rotation mirror goniophotometer. (LSG-5000/LSG-2000, in the case of insufficient budget and testing the LED luminaire, horizontal goniophotometer can also be selected)
3.    The length of the darkroom (length of light path) shall be guaranteed at least 6 times longer than the longest axis of the luminaire to be measured.
4.    If need to test the spatial color distribution, the darkroom should be equipped with a special spectroradiometer and a corresponding color detector. (LSG-1800BCCD/LSG-2000CCD/LSG-5000CCD meets all requirements)

At present,there are other types of goniophotometer on the market such as double rotation mirror goniophotometer. Although it can shorten the length of the darkroom, but the mirror can’t reflect the light by 100%. Adding one mirror also can increase the test error and the angle between the mirrors should be strictly controlled, otherwise easy to affect the final test results.There are some near field rotation detector goniophotometers. Because of the limit of distance, they cannot test larger size of lamp. At the same time because there is no light trap and light bar, once the darkroom is broken, it could have an impact on the test results. There also is a limit of occasion.
Lisun develops the LSG-1800B/LSG-1800BCCD horizontal goniophotometer, LSG-2000/LSG-2000CCD rotation mirror goniophotometer, LSG-5000/LSG-5000CCD rotation mirror & rotation detector goniophotometer according to years experience of research and development in the field of optical detection equipment, according to the different needs of customers, according to different application environments. Win the favor of large numbers of customers in the domestic and foreign markets. While providing the best cost-effective products, Lisun also ensure a high test accuracy and timely after-sales service.

Lumen test difference between integrating sphere and goniophotometer

As well as we know that for the LED luminaires lumen test, the CIE121: 1966 Clause 6.1, CIE127-2007 Clause 6.2 and IES-LM-79-08 Clause 9.0 are mentioned two luminous flux test method: the first is adoption integrating sphere+photometer or spectrometer(recommend by CIE121: 1966 Clause 6.1.1, CIE127-2007 Clause 6.2.and IES-LM-79-08 Clause 9.0), this kind of test method is relative measurement method on lumen test; the second is photometric method which is adoption goniophotometer, this kind of test way is absolute measuring method. If adoption integrating sphere and photometric method to test same one LED lamp, we will find luminous flux data of two test method have big difference. This article is mainly discuss luminous flux test difference at integrating sphere and goniophotometer.

The principle of integrating sphere measuring total luminous flux by calibrated standard lamp. Due to there will be use a calibrated standard lamp, so there’s no need to know the integrating sphere’s output luminous flux, we can calculate the SSL product’s luminous flux by compare with standard lamp. Generally speaking, the integrating sphere test method suitable for small size LED lamp to measuring lumen and color parameters, this is lumen relative test method, moreover, the integrating sphere test method have quick test speed and it needn’t dark room advantages etc. Normally, if lamp size is small or like single LED, the test result and accuracy will be much better.

If adoption integrating sphere method testing big size LED luminaires, it have some better disadvantages compared with photometric method. When use integrating sphere test LED luminaires, there have a fact that the LED luminaires have different types, such as single LED, LED bulb, LED luminaires and others, the type of LED luminaires have big influence for final total luminous flux measurement. Meantime, integrating sphere test method need to do calibration procedure. Normally, if test LED luminaires, the standard lamp have to keep same emission characteristics with tested LED luminaires, the standard lamp adoption white LED will be best way. Of course, other type lamp also can used as standard lamp, but the test accuracy will be impacted. The test way will bring some difference, usually we use the 4π test way to test a lamp which emitting the lighting at 360° direction and the tested lamp should be placed in the centre position of the integrating sphere(recommend by IESLM-79-08 Clause 9.2.5). This is the best way to test LED luminaires; if the tested luminaries emitting the lighting at fixed direction, such as LED panel, LED street light or others, we need use 2π test way which means test the luminaries should be mounted on the one side of integrating sphere(recommend by IESLM-79-08 Clause 9.2.5). For the 4π test way; if the tested luminaries output power is too big or the the lamp shell have large size, there will be happen self-absorption effect more or less, then we need to use a auxiliary lamp(recommend by IESLM-79-08 Clause 9.1.5) to avoid the error. Generally speaking, the integrating sphere method is suitable for the compact LED and small size LED lighting. The test result of the luminaries flux can be achieve high accuracy and stability by this way; if use integrating sphere testing large size LED luminaries, the integrating sphere method have obviously defect, this time, the the luminaries flux data is not accurate and stable.

Adoption goniophotometer measuring total lumen which is photometric method, and this way have small limitation on the lumen test. The test principle of photometric method is use goniophotometer measuring all direction’s intensity distribution (or show the illuminance of light source at limited distance), through collection the intensity data at different direction to calculate the total lumen. Compared with the integrating sphere method, due to the difference of test light source’s intensity distribution, the photometric method don’t exist error in the theory, as the photometric method is absolute test method on the lumen test. It doesn’t need calibrated total luminous flux standard lamp, but it need longer test time for each sample. The photometric method which will adoption goniophotometer device, and there will be mentioned the type C Goniophotometer(recommend by IES-LM-79-08 Clause 9.3.1 and CIE121:1996 Clause 3.2 etc), dark room, test distance(mentioned by IES-LM-79-08 Clause 9.3 and CIE121:1996 Clause 6.2.1.4).

The difference of testing total lumen output consist of type of goniophotometer, test method(CIE121: 1996 Clause 3.4.2, Clause 3.4.1 and Clause 3.4.3), test distance and detector level etc. According to different type of LED luminaires, we can adjustment the relevant test method or testing device, such as if tested luminaires belong to narrow beam angle SSL product, we can use compact goniophotometer; selection Type C Goniophotometer, adjust test distance, choose higher level Class L detector(detector details classification description here: article-id-70.html) which can help achieve high precision measurement. In the practice testing, the photometric method can achieve luminous flux data’s highest measurement, due to some limitations inherent of integrating sphere test method, it’s impossible to remove the test tolerance, the only we can do is try best to reduce the test tolerance; but for the photometric method, there almost haven’t too much limitations and we can replace the test instrument, adjustment system configuration and change test method to fix this test tolerance.

As explained above, the most simple way to measuring LED luminaires luminous flux is adoption integrating sphere and photometric meter, this way is meet visual flux spatial demand, we can use a fixed front-end photometric meter to measure the total flux and the test time is fast and convenient. By comparison with a standard light source which keep have similar spatial and spectral distribution characteristics of tested luminaires to measuring luminous flux, so this way will be need use a calibrated standard lamp. Comparing with goniophotometer, the integrating sphere and photometric meter have high test speed, but when tested LED luminaires have different spatial intensity distribution characteristics from standard lamp, it’s easy to cause test tolerance. This kind of test tolerance is hard to fix, so it should be adoption use a good design geometry integrating sphere and use standard LED standard lamp which have similar emission characteristics with tested LED luminaires to reduce this error.

As mentioned previously, if the shape of tested lamp is similar with tested luminaires, then the integrating sphere method will have better test accuracy. When measuring luminous flux, for the LED bulb, small size LED luminaires and tube which beam angle more than 180°, we should adoption integrating sphere and spectrometer to do 4π test. As for the big size LED panel, LED street lamp and traffic lamp which beam angle less 180°, if need adoption integrating sphere method, then the integrating sphere should have side opening structure to do 2π test or use auxiliary lamp for assistance test, but this way have complex test procedure and test result is uncertainty. For these small beam angle luminaires, the best way is adoption goniophotometer method and working on the dark room, this can make sure high accuracy. But when adoption goniophotometer method, we have a clear understanding for test difference of different test method. Normally, like the LED panel, the best test method is C-γ; for the traffic lamp and spotlights will choose B-β test. At the same time, both test methods are need at dark room environmental, comparing with integrating sphere, the goniophotometer need more professional test environmental and professional engineer. In summary, the measurement principle, environment and test methods of the integrating sphere and the distributed spectrometer are different, and the measurement results are not comparable. We can choose the right way to test according to different standards and different requirements.

In summary, both integrating sphere and goniophotometer method have different measuring principle, environmental and testing methods, the both measurement results are not comparable. We can based on different standards and requirements to selection suitable test way.

In order to better compared test result, we used the spectrometer, integrating sphere and goniophotometer to testing LED bulb and street lamp. The test report as below, we can refer this.

Lumen test difference between integrating sphere and goniophotometer

Lumen test difference between integrating sphere and goniophotometer

Lumen test difference between integrating sphere and goniophotometer

Lumen test difference between integrating sphere and goniophotometer