Research Note: LED chip-on-board packaging technology for strict colour tolerance

2017 ◽  
Vol 49 (8) ◽  
pp. 1052-1057
Author(s):  
J Zhang ◽  
P Ge ◽  
Z Zhou ◽  
D Liu ◽  
H Wang ◽  
...  
Keyword(s):  
Research Note ◽  
Luminous Efficacy ◽  
Packaging Technology ◽  
Colour Temperature ◽  
Colour Rendering ◽  
Method Show

In the field of LED packaging, people usually pay more attention to colour temperature, luminous efficacy and colour rendering than colour tolerance. This paper focuses on how to meet strict colour tolerances in the process of chip-on-board packaging. The McAdam ellipses are used to explain the meaning of colour tolerance. A method based on adjusting the amount of phosphor glue and the proportions of different phosphors it contains is described. Measurements on samples packaged according to this method show that it makes it possible to meet strict colour tolerance requirements.

scholarly journals Influence of Peak Wavelengths on Properties of Mixed-LED White-Light Sources

2010 ◽  
Vol 2010 ◽  
pp. 1-8 ◽  
Author(s):  
Snjezana Soltic ◽  
Andrew N. Chalmers
Keyword(s):  
Light Source ◽  
White Light ◽  
Light Sources ◽  
Peak Wavelength ◽  
White Light Source ◽  
Luminous Efficacy ◽  
Colour Temperature ◽  
Colour Rendering

The purpose of this investigation is to quantify the influence of the peak wavelength shifts in commercially available LEDs on the characteristics of the mixed-LED white-light sources. For this purpose, a tetrachromatic spectrum was optimized and then subjected to deviations in the peak wavelengths. A total of 882 combinations of peak wavelength values were evaluated, and the results are reported in terms of correlated colour temperature, colour-rendering properties, and radiant luminous efficacy. The results show that there can be significant changes in the characteristics of the source under these conditions. Such changes are highly likely to present problems when dealing with applications where an effective and accurate white-light source is important.

scholarly journals Stacked phosphor coating technology for white LEDs with high colour temperature and high colour rendering index

2017 ◽  
Vol 51 (1) ◽  
pp. 147-153 ◽  
Author(s):  
P Ge ◽  
Z Zhou ◽  
J Zhang ◽  
H Wang
Keyword(s):  
Light Sources ◽  
White Led ◽  
Phosphor Powder ◽  
Phosphor Layer ◽  
Coating Technology ◽  
Luminous Efficacy ◽  
Colour Temperature ◽  
White Leds ◽  
Phosphor Coating ◽  
Colour Rendering

Existing white LEDs use a blue LED chip to stimulate phosphor powder to form white light. The surface coated with a phosphor layer directly affects the colour rendering index, the luminous efficacy and the colour temperature. We have encapsulated a white LED source with chip-on-board packaging to meet the requirements for a high power, high colour temperature, high colour rendering index LED using stacked phosphor coating. This chip-on-board white LED light source can achieve a colour rendering index over 95 and a luminous efficacy over 100 lm/W while the colour temperature is 5700 K. This technology can be widely used in commercial lighting applications where high quality light sources are needed.

LED chip-on-board package with high colour rendering index and high luminous efficacy

2017 ◽  
Vol 50 (3) ◽  
pp. 482-488 ◽  
Author(s):  
Z Zhou ◽  
H Wang ◽  
J Zhang ◽  
J Su ◽  
P Ge
Keyword(s):  
White Light ◽  
Power Distribution ◽  
Spectral Power ◽  
White Led ◽  
Phosphor Powder ◽  
Phosphor Layer ◽  
Luminous Efficacy ◽  
Colour Temperature ◽  
Spectral Power Distribution ◽  
Colour Rendering

Existing white light LED technology uses a blue light LED chip to stimulate a phosphor powder to form white light. The phosphor layer on the surface directly affects the colour rendering index, luminous efficacy and colour temperature of the LED. We propose a high power, white LED, chip-on-board package technology to achieve high colour rendering index and high luminous efficacy by optimising the spectral power distribution. The chip-on-board package light source can achieve a colour rendering index over 90 and a luminous efficacy over 90 lm/W while the power is 45W. It can be widely used in commercial lighting applications.

Analysis of Characteristics of Halogen and LED Automobile Lamps

2020 ◽  
pp. 57-62
Author(s):  
Olga Yu. Kovalenko ◽  
Yulia A. Zhuravlyova
Keyword(s):  
Power Consumption ◽  
Flip Chip ◽  
Weather Conditions ◽  
Luminous Flux ◽  
Luminous Efficacy ◽  
Colour Temperature ◽  
Study Results ◽  
Calculation Results ◽  
Mandatory Rules ◽  
Halogen Lamps

This work contains analysis of characteristics of automobile lamps by Philips, KOITO, ETI flip chip LEDs, Osram, General Electric (GE), Gtinthebox, OSLAMPledbulbs with H1, H4, H7, H11 caps: luminous flux, luminous efficacy, correlated colour temperature. Characteristics of the studied samples are analysed before the operation of the lamps. The analysis of the calculation results allows us to make a conclusion that the values of correlated colour temperature of halogen lamps are close to the parameters declared by manufacturers. The analysis of the study results has shown that, based on actual values of correlated colour temperature, it is not advisable to use LED lamps in unfavourable weather conditions (such as rain, fog, snow). The results of the study demonstrate that there is a slight dispersion of actual values of luminous flux of halogen lamps by different manufacturers. Maximum variation between values of luminous flux of different lamps does not exceed 14 %. The analysis of the measurement results has shown that actual values of luminous flux of all halogen lamps comply with the mandatory rules specified in the UN/ECE Regulation No. 37 and luminous flux of LED lamps exceeds maximum allowable value by more than 8 %. Luminous efficacy of LED lamps is higher than that of halogen lamps: more than 82 lm/W and lower power consumption. The results of the measurements have shown that power consumption of a LED automobile lamp is lower than that of similar halogen lamps by 3 times and their luminous efficacy is higher by 5 times.

scholarly journals Towards the Optimum Light Source Spectrum

2010 ◽  
Vol 2010 ◽  
pp. 1-9 ◽  
Author(s):  
Andrew Chalmers ◽  
Snjezana Soltic
Keyword(s):  
Light Source ◽  
Large Scale ◽  
Source Spectrum ◽  
Light Sources ◽  
Luminous Efficacy ◽  
Light Emitting ◽  
Spectral Bands ◽  
Good Energy ◽  
Lighting Systems ◽  
Colour Rendering

This paper is concerned with designing light source spectra for optimum luminous efficacy and colour rendering. We demonstrate that it is possible to design light sources that can provide both good colour rendering and high luminous efficacy by combining the outputs of a number of narrowband spectral constituents. Also, the achievable results depend on the numbers and wavelengths of the different spectral bands utilized in the mixture. Practical realization of these concepts has been demonstrated in this pilot study which combines a number of simulations with tests using real LEDs (light emitting diodes). Such sources are capable of providing highly efficient lighting systems with good energy conservation potential. Further research is underway to investigate the practicalities of our proposals in relation to large-scale light source production.

VISUAL EFFECTS OF OBJECTS UNDER METAMERISM WITH MULTI-SPECTRAL LIGHT SOURCE

2021 ◽  
Author(s):  
Y.M. Li ◽  
H. Fan ◽  
C.H. Lin ◽  
J.U. Chong ◽  
T.X. Lee
Keyword(s):  
Light Source ◽  
Positive Relationship ◽  
Target Object ◽  
Visual Effects ◽  
Colour Temperature ◽  
Lighting Conditions ◽  
The Future ◽  
Convenience Sampling ◽  
Colour Rendering

This study attempts to simulate the metamerism colour, and the guava was used as the target object. We design four sets of metamers with a correlated colour temperature of 4000K and an illuminance of 750lux. The light source was simulated in the LED cube. The subjects with convenience sampling observed the visual effects, including look delicious, colourful, and colour rendering of guava under metamerism, then analysed its relationship with CRI and CQS. The results showed that colour rendering and visual effects are not a positive relationship, and the effect of CQS is closer to the visual effects of the subjects. The results of this study can be used as a reference for light source lighting designers as a basis for improving lighting conditions. In the future, we can collect databases for the different objects with an optimized multi-spectral light source.

The development of a colour discrimination index

2017 ◽  
Vol 50 (5) ◽  
pp. 681-700 ◽  
Author(s):  
L Xu ◽  
MR Luo ◽  
M Pointer
Keyword(s):  
Surgical Procedures ◽  
Discrimination Index ◽  
Colour Discrimination ◽  
Colour Space ◽  
Colour Temperature ◽  
Industrial Inspection ◽  
The Difference ◽  
Colour Rendering ◽  
Three Components

One aspect of colour rendering is to discern the difference between colours and colour discrimination. This is important for applications such as surgical procedures and industrial inspection. Two psychophysical experiments were conducted using computer generated images and real materials, including stone, wood and organs. The results were used to develop a colour discrimination index which includes three components: the CAM02-UCS uniform colour space, the correlated colour temperature and a set of test samples.

The effect of correlated colour temperature of lighting on thermal sensation and thermal comfort in a simulated indoor workplace

2016 ◽  
Vol 27 (3) ◽  
pp. 308-316 ◽  
Author(s):  
Rupak R Baniya ◽  
Eino Tetri ◽  
Jukka Virtanen ◽  
Liisa Halonen
Keyword(s):  
Thermal Comfort ◽  
Room Temperature ◽  
Thermal Sensation ◽  
Light Emitting Diode ◽  
Air Velocity ◽  
Light Emitting ◽  
Colour Temperature ◽  
Test Room ◽  
Illuminance Level ◽  
Colour Rendering

The ‘hue-heat’ hypothesis states that an environment which has wavelengths predominantly toward the red end of the visual spectrum feels ‘warm’ and one with wavelengths mainly toward the blue end feels ‘cool’. In order to test the hypothesis and to study the impacts of the correlated colour temperature of a light source on thermal sensation and thermal comfort, a study was conducted in a test room illuminated with an Light Emitting Diode (LED) lighting system with an adjustable correlated colour temperature where air temperature, air velocity, and relative humidity were kept constant. The correlated colour temperature of lighting inside the test room was changed gradually while keeping the colour rendering index values greater than 90, an illuminance level of 500 lx, and chromaticity difference (Duv) values within the limits of ±0.005. Sixteen study subjects were exposed to a ‘high room temperature’ (25℃) and a ‘low room temperature’ (20℃) on different days. The subjects were adapted to low correlated colour temperature (2700 K), medium correlated colour temperature (4000 K), and high correlated colour temperature (6200 K) lighting for 10 min and subsequently completed the questionnaire about their thermal comfort and thermal sensation. The results of this survey did not provide support for the hue-heat hypothesis and indicated that people felt thermally more comfortable in an indoor workplace at the correlated colour temperature of 4000 K than at the correlated colour temperature of 2700 K or 6200 K.

A white–cyan-red LED system for low correlated colour temperature lighting

2015 ◽  
Vol 49 (3) ◽  
pp. 343-356 ◽  
Author(s):  
M Chakrabarti ◽  
A Thorseth ◽  
DD Corell ◽  
C Dam-Hansen
Keyword(s):  
White Light ◽  
Colour Temperature ◽  
White Leds ◽  
Geometrical Modelling ◽  
Red Led ◽  
Colour Gamut ◽  
Museum Display ◽  
Colour Rendering ◽  
Red Leds ◽  
Planckian Locus

A white LED complemented by cyan and red LEDs is a good candidate for achieving high colour rendering at low correlated colour temperatures. This is usually very difficult with commercially available white LEDs. In addition, the system is able to replace incandescent lighting in many applications; for example, the lighting for museum display cases. To investigate and optimize the colour and light distribution properties, both spectral and geometrical modelling are used. Mapping of the possible combinations of LEDs is used to locate the optimal solutions within the colour gamut, with emphasis on chromaticity and colour rendering indices. A geometric optical model is used to design and optimize the homogeneity of the colour and light intensity distribution as a function of angle. The resulting system produces diffused homogeneous white light with a tunable correlated colour temperature from 2000 K to 2400 K. Within this range the white light is characterized by a high general colour rendering index (Ra > 90), special colour rendering indices for saturated red objects (R9 > 85), and low chromaticity distance (Duv) from the Planckian locus (Duv < 2 × 10−3).

Sign in / Sign up

Export Citation Format

Share Document