Dissertations / Theses on the topic 'Luminance uniformity'

Ljus påverkar människan psykiskologiskt och fysiskt, trots detta är de krav som idag finns på belysningen inte tillräckliga för att beakta de miljöegenskaper ljuset bidrar med. Ett visst ljus i kombination med en viss färg och material påverkar människan på olika sätt. De krav som ställs tar bara hänsyn till de tekniska aspekterna. Hur ljus estetiskt påverkar ett rum är en faktor detta arbete tar hänsyn till, då det påverkar människans välmående. Detta projekt behandlar två olika rum, ett rum för träning och behandling samt ett väntrum på en sjukgymnastikavdelning tillhörande Södersjukhuset i Stockholm. Dessa två rum har genomgått en ljusstudie och ljusplanering med syfte att skapa en ljussättning som är anpassad för sitt ändamål och som upplevs trivsam och behaglig. Vissa skillnader mellan projektets framtagna förslag och ett verkligt projekterat förslag har även jämförts. För att genomföra ljusstudien och ljusplaneringen har beräkningar utförts i belysningsprogrammet RELUX. På grund av att ljus inte enbart kan simuleras med hjälp av datorprogram har även fysiska modeller byggts för att analysera valet av färgtemperatur. Studiebesök på sjukgymnastpraktiker och träningsanläggningar har gjorts för att få inspiration. Även intervjuer med sjukgymnaster har gjorts för att få förståelse för vilka faktorer som måste tas hänsyn till vid en ljusplanering för denna typ av verksamhet. Litteraturstudier har gjorts för att få en djupare kunskap i hur ljus agerar i olika miljöer. Ljusplaneringen har resulterat i en jämn och god belysning i de två rummen. Kraven för belysning enligt SS-EN 12464–1:2011, har uppfyllts. Ljuskällornas färgtemperaturer har fastställts med hänsyn till färgerna i rummen, varmvit i väntrummet och neutral i tränings-/behandlingsrummet. Armaturer med uppljus och nedljus har valts i syfte att minska bländning och luminansskillnader. Downlights har valts för att belysa väggar och föremål. För att skapa en upplivande atmosfär i rummen har även dekorbelysning använts. Slutsatsen av detta arbete har visat att det är viktigt att ta hänsyn till en jämn belysning, anpassa belysningen och ljuskällans färgtemperatur efter färgsättning och material samt att anpassa belysningen efter alla synuppgifter som kan komma att krävas av personen som skall utföra arbetsuppgifter i rummet.
Light affects humans psychologically and physically, despite this the lighting requirements does not pay regard to the environmental characteristics that light contributes with. A specific light in combination with a specific color and material affects the human being in different ways. The lighting requirements only takes the technical aspects into account. In this project consideration will be given to how the light aesthetic affects the well-being. In this project two rooms will be processed, a waiting room as well as a room meant for rehabilitation. The rooms are placed in a building that includes physiotherapy at Södersjukhuset in Stockholm. The rooms have participated in a light study to create a light environment that is adjusted to its purpose as well as it is pleasantly perceived. Some differences between this lighting project and an actual lighting project have been compared. To perform this light study, various calculations have been done in the lighting planning software RELUX. Light can not solely be simulated with computer software, therefore physical models have been built to analyze the choice of color temperature. Visits to physiotherapy practices and training facilities have been done for inspirational purposes. Interviews with physiotherapists have also been done to reach a better understanding of what factors are needed to be taken under consideration while planning the lighting. Literature studies have been made to get a deeper knowledge in how light reacts in different environments. The lighting planning has resulted in an even lighting in both rooms. The requirements for lighting according to SS-EN 12464-1:2011 have been fulfilled. The different color temperatures of the light sources have been determined regarding the colors of the rooms, warm white in the waiting room and neutral in the rehabilitation room. Armatures with up and down lights have been chosen with the purpose of decreasing glare luminary differences. Downlights have been chosen to lighten up the walls and various objects. To create an uplifting atmosphere in the room, decor lighting have also been used. The conclusion of this work has shown that it is important to take luminance uniformity, adapt the light and color temperature to the room and its colors and materials into account. It is also important to adapt the light to all the different visual works that can take place in the room.

The first part of the thesis is research, which deals with electric luminaires and especially their light-active parts. Subsequently is described the problem of a specific luminaire, which is used during the control of the surface structure of materials. The next part of the thesis deals with the simulation of the current luminaire and the simulations of the proposed solutions that eliminate the shortcomings of the luminaire. The conclusion of this thesis is the evaluation of the originally used luminaire and the benefits of the proposed solution, which showed the best results in the simulation.

碩士
南台科技大學
電機工程系
95
LCDs (Liquid-Crystal Displays) is one of the most popular electronic products in the information age. It is the reason why there are so many display manufactures devoting many resources into it. However, there are two important issues are always a concern to the display industry, that is luminance and luminance uniformity of a display. It is continuous challenge faced by the backlight manufacturers to improve luminance and luminance uniformity of its products under continuous cost-down pressure in today’s fiercely competing market. In direct-type backlight units (BLUs), the lamps are aligned parallelly with even (or uneven) spacing. This results in “lamp mura”, luminance non-uniformity. Additional, the technical trend, thinness and lightweight, in LCD backlight industry, worsen this problem. In this work, we propose a new concept, beamsplitting going with diffusing, to tackle the problem of luminance non-uniformity in direct-type BLUs. With the implementation of this idea, we expect that the numbers of optical films can be further reduced. The goal of cost-down, thinness, and luminance uniformity can be achieved at one time. In this study, experimental work has been performed by using beam splitters or reflection films with beansplittering capability (DVR and ESR) that will split light proportionally according to specified design case, as well as other optical films (such as up diffuser, bottom diffuser and prism lens) to create a novel direct-type BLU structure. Luminance measurements and analysis are carried out to determine the optimal design parameters for beamsplitters and the other optical film(s). In conclusion, the issue of luminance uniformity had been solved and the goal of thinness is achieved. Two major structures are proposed. For general use, a combination of a beam splitter and a diffuser film will meet the specification. For high-luminance products, instead of beamsplitter, DVR is applied as well as other optical films, including bottom diffuser, prism lens, and up diffuser, to meet the demand in luminance.

碩士
國立聯合大學
光電工程學系碩士班
98
Luminance and color uniformity measurements are very important issues for evaluating the quality of flat panel displays . In this thesis, one charge-coupled device (CCD) camera was used as a measuring tool, combined with DAQ card and software program , one-time acquisitions and analyses could provide the brightness values and color values of all points within the panel. Firstly, one lamp inside an integral sphere was simulated as a light source with more than 98% luminance uniformity, our CCD camera measured the luminance and color values. Based on the results compared with those measured by commercial single-point luminance colorimeter (BM7-A), we made the nonlinear correction of flat-field of camera lens and derived a conversion matrix for color values and gray levels of CCD pixels. Secondly, we set up a standard measurement process. The calibrated CCD camera combined with the LabVIEW software was used as the measurement instruments, the experimental results showed that under the illumination of standard source A, the luminance and chrominance values at the same location could be controlled within ± 3% error range. Finally, this CCD camera system was used for measuring luminance and color values under illuminations of another light sources, the errors were increased as the difference between the optical spectrum of measured light source and standard A source became larger. The main source of errors was from the inaccurate linear transformation matrix between the spectral response of standard CIE XYZ and our camera’s filters.

碩士
逢甲大學
工業工程與系統管理學研究所
100
With the increment of environmental protection consciousness, many countries had begun to discuss the issues of energy conservation and carbon reduction. Lighting, for example, is one of necessary requirements in the human life. In order to make people relieved and relaxed in the environment, lighting must be enough. However, excessive lighting equipments will cause a huge cost of a society. Therefore, how to save the energy and improve lighting efficiency is an important issue now. This research analyzes the effects of total illuminance levels and illuminance uniformity for six types of hallway lighting arrangements by manipulating the numbers of LEDs and the distances between LED lights. The participants assessed the hallway lighting arrangements and then rated on a questionnaire developed for this research with regard to the perceived safety. The experimental results show that the illuminance uniformity has strong impacts to the perceived safety. Two regression models were further developed for forecasting preferences of different lighting distributions. The first one used information obtained by walking through the hallways of different lighting arrangements. Its R square was above 0.570. The other one used information obtained by viewing the hallway lighting arrangements without walkthrough. Its R square was above 0.607.

碩士
國立中央大學
光電科學研究所碩士在職專班
96
This research approach the study of luminance and uniformity characteristics with new invented secondary optical lens, we called it as “lightguide-diffusive component”, with wide emission angle is designed for thin direct LED backlight . The LED backlight module composes ,at least, a part of “light source”, a secondary “lightguide-diffusive component “, a FPC for LED lighting and a new designed micro-structure reflective bottom surface on “lightguide-diffusive component “. Through the new designed lightguide-diffusive component , the emission profile of a single LED is modified to the situations of more illuminant and more uniformity. This new designed secondary optical lens is shaped as module type to cover the LED array results in a more uniform spatial light energy distribution on the emission plane of LED backlight. The new invented in this research thereto being apply the invention-patent of R.O.C.

碩士
國立成功大學
電機工程學系
102
Active-matrix organic light-emitting diode displays have many advantages, such as wide-viewing angle, fast response time and excellent color reproducibility. This thesis presents five compensation pixel circuits for use in AMOLED displays to solve the issues including deviations of electrical characteristics of thin-film transistors, such as low-temperature polycrystalline-silicon, amorphous indium-gallium-zinc-oxide technology, and OLED degradation as well as power line I-R drop. The first circuit is utilized of simple 2T1C structure for use in 3D Full HD displays, and it compensates for threshold voltage variation. Howerver, the external swith circuit increases the system costs. Although the second circuit compensates for threshold voltage variation without external swith circuit, it suffers from VDD I-R drop. The third circuit compensates for not only threshold voltage variation but also VDD I-R drop and mobility variation. The previous three circuits are voltage programming LTPS pixel circuits, and the following two a-IGZO pixel circuits are operated with current-biased voltage-programming method. Although the fourth circuit compensates for threshold voltage shift of the driving TFT and the OLED with simple operation, the structure 5T1C is more complex. The last circuit with simple 3T1C structure can also compensate for threshold voltage shift of the driving TFT and the OLED, but the uniformity of luminance would be affected by parasitic resistance and capacitance of SCAN line signals.

碩士
逢甲大學
光電研究所
96
Color and luminance uniformity are important parameters for evaluating the image quality of liquid crystal displays (LCD). This study presents a hyperspectral imaging system for quick and full-field measurement of these parameters. In the system, a hyperspectral camera, based on a prism-grating-prism dispersing element configuration, and line-scanning technique are utilized to measure and store the intensity as a function of wavelength for each point on the surface of the LCD under test. Therefore the measured spectrograph image is actually a three-dimensional (3D) image. The chromaticity coordinate and luminance distribution of the LCD are then derived from this 3D image. A 21-inch LCD was measured by the hyperspectral camera and a spectroradiometer. Comparing the results obtained with these two different instruments yields that the average deviations of measured luminance, x chromaticity coordinate, and y chromaticity coordinate are around 2 %, 0.001, and 0.006, respectively. In addition to the saving in measurement time, experimental results also show the proposed imaging system can provide more information of the LCD image quality than conventional methods.

碩士
國立中興大學
機械工程學系所
101
The light guide panel is a part of the back light module, which evenly spreads light sources in the liquid crystal display (LCD) to destroy total reflection. Light will be transmitted into the light guide panel and can be reflected, scattered, and refracted appropriately via the micro structure, which allows light to uniformly enter the panel. Therefore, the light guide panel’s material, microstructures and production procedure is always the focus of the study. Unlike the conventional direct screen printing or plastics injection molding method, In this study, we used Carbon dioxide laser (Maximum power 25W) to manufacture PMMA light guide panel, through to set the power, speed and the number of engraving. Design the V-shaped grooves by configure the side angle of inclination (1˚~4˚), fixed depth and pitch (1mm~3mm, increasing range is 0.5mm), by changed the scattered patterns to improve the performance of the light guide panel. And to explore the V-Cut patterns through this processing method that can obtain the best optical illuminance, luminance and uniformity. Look forward to use this relatively rapid manufacturing methods, to find an alternative to the past, expensive and time-consuming manufacturing process. Experimental results show that the enhancement of the optical properties for the light guide panel, at the optical effect of illumination aspect first of all, to change the light guide panel of the flank angle is better than to change the fixed depth. As to the luminance aspect, its can be found that the pattern of the V-shaped grooves in the flank angle of 4˚ or the depth is fixed at 0.8 millimeters, its optical properties is higher. But the result tends to exponential shape decreased, leading to the uniformity lower. In addition, these two properties can be found its match on the small pitch premise, there will get better results.

碩士
國立高雄第一科技大學
光電工程研究所
96
In this thesis, a light guide plate is designed to uniform the light emitted from the light source of LEDs beneath it and form a backlight module which satisfy the requirement of the specification of its kind. The relationship between the structure parameters of light guide plate and the uniformity of luminance is simulated and analyzed by the Advanced System Analysis Program (ASAP) optical software. The suitable parameters are chosen to improve the non-uniformity of luminance. At first, the uniformity of luminance using a not optimized light guide plate for a 32 inches direct backlight module is about 69.25％. After applying the parameters optimization procedure, the uniformity of luminance can be achieved above 85％. Finally, the parameters optimization procedure is applied onto other large scales of backlight modules and proved to be able to obtain the high quality of luminance uniformity as well.

碩士
國立臺灣科技大學
自動化及控制研究所
95
Based on the superior properties of the LEDs such as, low powers consumption, quick electronic response, long lifetime and wide viewing angle, they can be generally used for information display, communication, indicator of consuming electronic product. However, the requirement of the display quality which includes luminance uniformity and color performance is more concerned by the people. The LEDs module inspection and luminance adjustment are still relying on labor work, which has some disadvantages of low speed and high cost. And the human inspection results may be different. It does need an automation inspection and automatic tuning system to improve the luminance uniformity and increase the competitiveness of the LED display industry. In this study, we integrate an automated optical inspection technology, luminance calibration and compensated driver to improve the display uniformity of a 16X16 LEDs module. Firstly, a spectrum meter is used to analyze the difference of LED’s wavelength. Then a colorimeter/luminance meter is equipped to measure each LED within the LED module which is put on a XY-table. The measured luminance data are analyzed and a compensated Look Up Table (LUT) is created according to the LED’s luminance curves. A LED module with 16 by 16 pixels was lighted and compensated in this paper. The improved luminance uniformity of over 95% was achieved. The proposed compensation mechanism can improve the luminance uniformity and could be applied into either automatic voltage compensated driver or pulse width modulation with constant current driving to solve the problem of luminance uniformity of LED display panel. It could be very helpful to promote the LED application market.

碩士
國立中央大學
光電科學研究所
99
The technologies used for the brightness and color testing of the LED (Light Emitting Diode) modules on the market, are mostly remain in the manual ways, manual inspection could induce the human errors and cause the damage of human eyes. Due to the different operators, timing and environment, the results of the inspection might be different. The study is utilizing the concept of the neural networks, using the back-propagation neural network method, to construct a LED module automatic inspection system. The uniformity of the brightness and the color deviation of the module were tested. The CCD camera captures the red, green, and blue grayscale values from the samples under test, the captured data are divided into 3 different bins, one for the learning, one for the testing and retraining, and one for the final accuracy conformation purpose. The optical centroid qualified method is used for the LED RGB gray level images. The results of the study are fairly reasonable, some deviations are caused by the environmental factors, adding these samples to the learning bin, making some repeated learning, and the acceptable results are obtained. The fuzzy logic methodology is considered to be the future study for the advanced research, and more stable results would be expected. Keywords: LED, neural networks, back-propagation

碩士
國立臺灣科技大學
自動化及控制研究所
97
A TFT LCD is not a self-emitting display device. To achieve the purpose of display, the help of a backlight source is required. Therefore, the quality of display is affected directly by the function of a backlight source. Based on the superior properties of the LED such as non-mercury, long lifetime, and low powers consumption, a high power LED as a source of LCD backlight is the tendency presently. LED is becoming one of the most representative backlight sources. Consequently, the quality of image display is enhanced if the luminance uniformity of backlight source improved largely. A LCD direct-type light emitting diode backlight module of luminance uniformity inspection and compensation mechanism were constructed in this study. Firstly, it was analyzed and designed by an optical simulation software “Tracepro”. Secondly, the Taguchi Method and Grey Relational Analysis were used to find out better parameters for the proper white light source of a LCD panel. The experimental module consists of 4X4 white light LEDs in which four optical sensors were used to monitor the brightness of each 2X2 LEDs block. Thus, the backlight module has a feedback control ability to compensate the brightness of LEDs effectively. Therefore, it can improve the light uniformity to be applied in the backlight module of a LCD panel. The proposed feedback compensation mechanism of LED backlight module in this study has the ability to improve the light distribution of LED backlight module by built in optical sensors. The results showed that the improved brightness uniformity was over than 95%.

碩士
逢甲大學
工業工程與系統管理學研究所
96
The flat panel display technology industry has been intensely promoted by the Taiwanese government. Even though this industry has received a great deal of support, large-size LCD prices remain high because backlight unit (BLU)-related patents are held by foreign manufacturers, and costs therefore remain high. To circumvent these patents, the ITRI-ERSO (Industrial Technology Research Institute -Electronics Research & Service Organization) has developed a new backlight technology – namely, carbon nanotube backlight units (CNT-BLUs). However, CNT-BLU technology is still in the research and development stage. International standards groups, such as VESA, SPWG, and ISO, demand that the new technology must satisfy quality standards for luminance uniformity. Any monitor that shows irregular patterns (IRP) will not satisfy quality standards. IRP-centered non-uniformity method was developed to measure the luminance uniformity in this study. This method was compared with VESA and Line uniformity methods. In this study, 100 simulated CNT-BLU IRP images were displayed on LCD screens. Participants were asked to evaluate for each image according to a pre-defined standard. After the experiment, each simulated image was calculated for its luminance uniformity by three measurement methods (VESA, Line uniformity, IRP-Centered NonUniformity). The correlation coefficient value between human subjective evaluation and luminance uniformity were obtained. This correlation value was used as criterion for the comparison of three luminance measurements in the study. The results reveal that, compared with VESA and Line uniformity evaluation methods, the IRP-centered method has shown better results in two aspects: 1. Under three Irregular Patterns(Line, Region, and Mottled appereance), the average correlation coefficients were between -0.8 and -0.86 2. The average correlation coefficient of different severities of uniformity defects were between -0.77 and -0.88.

碩士
國立虎尾科技大學
光電與材料科技研究所
99
Since the efficiency of LED continually upgrading and their prices gradually approach with traditional light sources, makes a variety of luminaires began to use LED as a light source, but the LED optical properties different from conventional light sources, creating many of the products is not consistent with the relevant regulations, such as with beam distribution, illumination and glare, etc.. Traditionally, to solve the problem of uniformity of lighting, the way is installation a frosted glass or plastic diffuser, however, it will cause efficiency significantly reduced and adverse effect of uniformity, this paper focuses on the design of reflector, use CAD software to create initial model of reflector, and use TracePro and DiaLux which is the optical simulation software for analysis the lighting quality problems, as the Taguchi method in a shorter time and less number of experiments to complete parameter optimization, so the design with the Taguchi method, the reflector angle, the bend forming R angle and the reflectivity of reflector material as a parameter to Taguchi orthogonal arrays for optical simulation and analysis of variance with the parameters, optimization of the more influential factor. This research proposes a more rules of lighting design process, improve the speed and change the design of non-imaging optical design than the traditional reliance on personal experience of lighting design methods, and compare the control group of commercially available LED lamps, luminaire optimized design uniformity will be increased to 86.3%, UGR glare compared with the commercially luminaires reduced more than 30% , the final mold to produce the finished product and the actual measured value and simulated value of the comparative analysis, to verify the feasibility of this design method. The results showed that the optimization multi-reflector average illumination higher than the two commercially luminaires of 21.9% and 44.84%, and the uniformity improved 54.71% and 30.89%.