Luminous Intensity Measurement
Luminous intensity refers to the amount of light emitted in a specific direction. Unlike traditional light sources, LEDs emit highly concentrated light, making the inverse square law unsuitable for close-range measurements. To address this, the CIE127 standard defines two measurement conditions: Condition A (far field) and Condition B (near field). Both use a detector area of 1 cm². Typically, Condition B is preferred for measuring luminous intensity due to its practicality in real-world applications.
Luminous Flux and Luminous Efficacy Testing
Luminous flux represents the total amount of visible light emitted by a source. There are two main methods used for its measurement:
(1) Integration Method: In this method, both a standard lamp and the test lamp are placed inside an integrating sphere. Their respective readings on a photodetector are recorded as Es (standard lamp) and Ed (test lamp). Since the flux of the standard lamp (Φs) is known, the flux of the test lamp (Φd) can be calculated using Φd = Ed × Φs / Es. While this method is straightforward and based on the "point source" principle, it is sensitive to color temperature differences between the lamps, which may introduce significant errors.
(2) Spectroscopic Method: This approach calculates luminous flux by analyzing the spectral power distribution of the light. A monochromator is used to measure the spectrum of the standard lamp from 380 nm to 780 nm within the integrating sphere. The same process is repeated for the test lamp, and the results are compared to determine the luminous flux. This method offers higher accuracy, especially when precise spectral data is required.
Luminous efficacy measures how efficiently a light source converts electrical power into visible light. For LEDs, this is commonly measured using a constant current method, ensuring consistent performance evaluation.
Spectral Property Analysis
Spectral properties of LEDs include their spectral power distribution, color coordinates, color temperature, and color rendering index (CRI). These parameters help characterize the quality and performance of LED lighting.
The spectral power distribution describes the intensity of light at different wavelengths. It is typically measured using a spectrophotometer or monochromator, comparing the test source with a standard reference.
Color coordinates represent the chromaticity of a light source on a standardized color chart, often using the X-Y coordinate system. These values help identify the hue and saturation of the emitted light.
Color temperature indicates the perceived color of the light, expressed in Kelvin (K). It is derived from blackbody radiation theory and is crucial in determining the visual appearance of a light source in various environments.
Color rendering index (Ra) measures how accurately a light source reveals the true colors of objects. A higher Ra value means better color fidelity, making it a key factor in lighting design and application.
Light Intensity Distribution Testing
The distribution of light intensity across space is called the light intensity distribution. This is typically represented as a polar curve, showing how brightness varies with angle. Due to the complexity of multiple measurement points, automated goniophotometers are often used for accurate and efficient testing.
Impact of Temperature on LED Optical Performance
Temperature significantly affects the optical characteristics of LEDs. As temperature rises, the emission spectrum and color coordinates can shift, impacting light quality and efficiency. Understanding these effects is vital for optimizing LED performance and longevity.
Surface Brightness Measurement
Surface brightness refers to the luminous intensity per unit area in a specific direction. It is measured using specialized instruments such as surface brightness meters and aiming brightness meters, which have separate light paths for alignment and measurement.
Electrical Parameter Testing of LED Lamps
Key electrical parameters include forward voltage, reverse voltage, and reverse current. These are essential for evaluating the functionality and reliability of LED lamps. Two common testing approaches are:
(1) Measuring voltage at a constant current.
(2) Measuring current at a constant voltage.
For example, forward voltage is determined by applying a known current and measuring the resulting voltage drop. Reverse current is tested by applying a reverse voltage and recording the current flow. These tests ensure that LEDs operate safely and efficiently.
Thermal Characteristic Testing of LED Luminaires
Thermal management is critical for LED performance. Key thermal parameters include thermal resistance and junction temperature. Thermal resistance reflects how effectively heat is dissipated from the PN junction to the housing, while junction temperature indicates the actual operating temperature of the semiconductor.
Common methods for measuring these parameters include infrared imaging, spectroscopy, and electrical parameter analysis. Among them, the electrical parameter method is widely used because it relies on the linear relationship between forward voltage and junction temperature, offering a reliable and cost-effective solution.
Intern Editor: Liang Jieying
Sound module
Ningbo AST Industry Co.,Ltd has 17 Years Experiences to produce the Recordable sound module, sound module, sound chip, voice module, recordable sound chip,Musical module and other electronic modul. we can assure you of competive price,high quality,prompt delivery and technology supporting.
1. Sound Module Application:
Sound Module is one kind of electronic product which
mainly applied for Greeting cards,Christmas cards, promotion gifts, kids
books, newspapers, magazines or other products which have sounds.
2. Sound Module Classification:
We can produce different sound modules which have different functions:
A. Pre-record Sound Module ----The clients will
provide their sound files to us as MP3 or Wav Format,Then we programme
them into the Sound module,it will play the customized message.
The sound file can be from 1second to 480seconds
B. Recordable Module ---also called Self-recording
sound chip,we can record our own messages and playback them. Of
course,the message can be erased and re-recorded.
Recording time:6seconds,10seconds,20seconds,30seconds,60seconds,90seconds,120seconds,180seconds etc
C. Melody module --Which can play the Melody of the Happy Birthday,Merry Christmas,Slient Night and so on.
D. USB MP3 Module ---We Can download the
songs,musics,sentences,voice,advertising language from PC directly.
Which support SD Cards,TF Cards,U Disk and FM.LCD Display also can be
made
E. Programmable Voice Module --Also can be called DIY
Sound Chip,We provide the software and Programable Machine and the
Clients can be programmed them at their office,factory or Home. Which is
much suitable to small order quantity,but Prompt delivery order.
F. Waterproof Music Module --which usually are used by Children Cloths,Kids'Bib ,attract the children's attention or Sing the children's songs.
3. Sound Quality:Clearly and Loudly ( 16Khz Sampling Rate)
4. Activated way:
1) Pull String -- Pull the string to activate the sound.
2) Slide tongue,usually was used by greeting cards,open the cards,it will play the message automatically.
3) Push buttons--press the button to play the message/audio/music
4) Light sensor,usually was used by Gift box,newspaper. Open the Box or newspaper to play the message
5) vibration sensor,Move or shake it to play the customized audio
6) shadow sensor,if somebody walks front it,it will play the message.
7) Motion sensor,usually was used by Pop Display, advertising board
and so on.when somebody walks front it,it will play the message.
8) PIR (Infrared sensor),usually was used by Pop Display, advertising board and so on.when somebody walks front it,it will play the message.
5. Long Lifespan
6. Speaker:21mm,27mm,29mm,36mm,40mm,57mm etc. Plastic or Metal
7. Battery:AA, AAA, AG13, AG10, AG3 and so on environmental
8. PCB available: customize size or our existed standard size
9. PCB:Customized Size (OEM or ODM) or our existed standard size
10. Certification:CE ,Rohs
11. Export to: USA, UK,Canada,Germany,
Turkey,Russia,Poland,Switzerland,Netherland ,Frence Hungary
,Australia,New Zealand, Brazil, Columbia,Argentina,Thainland,Singapore ,
Malaysia and so on
Sound Module, Recordable Sound Chip, Recordable Sound Module
AST Industry Co.,LTD , https://www.astsoundchip.com
