首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 15 毫秒
1.
    
Abstract— Liquid‐crystal displays (LCDs) have notable variation in luminance and perceived contrast as a function of the angle from which they are viewed. Though this is an important performance issue for LCDs, most evaluation techniques for assessing this variation have been limited to laboratory settings. This study demonstrates the use of a photographic technique for such an evaluation. The technique is based on an actively cooled charge‐coupled‐device (CCD) detector in combination with a macro lens covering a circular angular range (θ) of ±42.5°. The camera was used to evaluate the luminance and perceived contrast properties of an LCD. Uniform field images corresponding to 17 equally spaced gray‐scale values in the digital driving level (DDL) range of the display system were acquired. The 12‐bit gray‐scale digital images produced by the camera were converted to luminance units (cd/m2) via the measured luminance vs. DDL response function of the camera. The changes in perceived contrast as a function of viewing angle were derived from the Barten model of the gray‐scale response of the human‐visual system using the methods proposed by the AAPM TG18 Report. The results of this photographic technique were compared to measurements acquired from a similar display using a Fourier‐optics‐based luminance meter. The results of the two methods generally agreed to within 5%. The photographic methods used were found to be accurate and robust for in‐field assessment of the angular response of LCDs over the FOV of the camera.  相似文献   

2.
    
Abstract— A viewing‐angle‐controllable liquid‐crystal display (LCD) is proposed. When the device is only driven by an in‐plane electric field, it exhibits a wide‐viewing‐angle (WVA) mode. And it exhibits narrow‐viewing‐angle (NVA) mode when it is driven by a vertical electric field as well as an in‐plane electric field. In this manner, the viewing angle of the device can be controlled from 100° to 30°. The device exhibits a good viewing‐angle‐controlling characteristic and high transmittance.  相似文献   

3.
    
Abstract— A wide‐view transflective liquid‐crystal display (LCD) capable of switching between transmissive and reflective modes in response to different ambient‐light conditions is proposed. This transflective LCD adopts a single‐cell‐gap multi‐domain vertical‐alignment (MVA) cell that exhibits high contrast ratio, wide‐viewing angle, and good light transmittance (T) and reflectance (R). Under proper cell optimization, a good match between the VT and VR curves can also be obtained for single‐gamma‐curve driving.  相似文献   

4.
    
Abstract— We demonstrate a novel TN‐display compensation film with excellent contrast and minimal color shift, meeting the requirements for avionics displays. The film configuration was identified via extensive computer modeling. The experimental implementation based on ROLIC's LPP/LCP (linearly photopolymerizable polymer/liquid‐crystal polymer) technology results in excellent agreement with theoretical predictions.  相似文献   

5.
    
Abstract— A continuous‐viewing‐angle‐controllable liquid‐crystal display (LCD) using a blue‐phase liquid crystal is proposed. To realize both wide‐viewing‐angle (WVA) mode and narrow‐viewing‐angle (NVA) mode with a single liquid‐crystal panel, each pixel is divided into a main pixel and a subpixel. The main pixel is for displaying images in both modes. The subpixel is for displaying images in WVA mode and controlling the viewing angle in NVA mode. The device exhibits a good viewing‐angle‐controlling characteristic and high transmittance.  相似文献   

6.
    
Abstract— The electro-optic effects and viewing-angle characteristics of some recently developed single-polarizer reflective liquid-crystal displays are compared under the same material parameters. The mixed-mode twisted-nematic cells and biaxial film-compensated thin homogeneous cells are promising for both direct-view and projection displays employing crossed polarizers. How to improve contrast ratio for the parallel-polarizer displays remains a technical challenge.  相似文献   

7.
    
Abstract— Autostereoscopic and polarization‐based stereoscopic 3‐D displays recreate 3‐D images by providing different images in the two eyes of an observer. This aim is achieved differently for these two families of 3‐D displays. It is shown that viewing‐angle measurements can be applied to characterize both types of displays. Viewing‐angle luminance measurements are made at different locations on the display surface for each view emitted by the display. For autostereoscopic displays, a Fourier‐optics instrument with an ultra‐high‐angular‐resolution VCMaster3D is used. For polarization‐based displays, a standard Fourier‐optics instrument with additional glass filters is used. Then, what will be seen by an observer in front of the display is computed. Monocular and binocular quality criteria (left‐ and right‐eye contrast, 3‐D contrast) was used to quantify the ability to perceive depth for any observer position. Qualified monocular and binocular viewing spaces (QMVS and QBVS) are deduced. Precise 3‐D characteristics are derived such as maximum 3‐D contrast, optical viewing freedom in each direction, color shifts, and standard contrast. A quantitative comparison between displays of all types becomes possible.  相似文献   

8.
Ji Ma  Li Xuan 《Displays》2013,34(4):293-300
Cholesteric liquid crystals (Ch-LCs) have been extensively studied due to their unique self-organized helical molecular structures and selective Bragg reflection properties, which exhibit great potentials for color displays and other practical applications. When functional, nanoscale molecular switches are doped in liquid crystals (LCs), the phases of the LCs or the molecular structures of the Ch-LCs can be changed upon the influence of external stimuli, such as light and temperature. In this paper, the photoresponsive molecular switch-based LCs for display applications are reviewed. The progress and effort in developing molecular switches, the principles of light-tuning, photo-addressed color displays, information processing, bistable displays and flexible displays are presented.  相似文献   

9.
    
Abstract— Viewing‐angle dependences of the contrast ratio and color shift of LCDs have been radically improved as evidenced by the increasing application of LCDs in high‐quality television. This paper describes the concept of optical compensation and the fundamental characteristics of the viewing‐angle property for various LC modes.  相似文献   

10.
    
Abstract— Advanced two‐ and three‐dimensional modelling was used to explain microscopic measurements on two different double‐domain twisted‐nematic liquid‐crystal‐display (TN‐LCD) configurations that were made using photoalignment. The shape of domain walls and their effect on the transmitted intensity were described correctly. For some double‐domain configurations, the brightness and contrast of the display will be affected by the domain walls.  相似文献   

11.
    
Abstract— The scribe‐and‐break method for glass cutting is widely used to separate individual liquid‐crystal‐display (LCD) panels from a larger motherglass substrate cell. Optimum glass‐scribing conditions including scribe‐wheel dimensions, scribing load, scribing speed, etc., have been determined based on practical manufacturing experience. However, there has been no systematic study to determine the scribing conditions necessary to avoid stray breakage. In this paper, the influence of the scribe‐wheel angle and diameter upon the scribing and breaking of an active‐matrix liquid‐crystal‐display (AMLCD) glass substrate, Corning Code1737F glass, was experimentally investigated for the case of simple single‐glass‐sheet separation. It was determined that an equation including the factors of scribe‐wheel tip angle and diameter can be used to predict median crack depth as a function of scribe load. It was further found that the breaking force of the scribed sheet was strongly influenced by the residual stress created during scribing. A wheel having a 130° tip angle and 4‐mm diameter demonstrated the best results for sheet separation in terms of the lowest breaking force without lateral crack propagation. In addition, increasing the time interval between scribing and separating was found to result in an increase in the breaking force required to separate the glass substrate.  相似文献   

12.
    
We propose a viewing angle switchable blue‐phase liquid crystal display with low voltage and high transmittance. In this device, in‐plane protrusions are used to lower operating voltage and improve the transmittance. Besides, the top electrode can control viewing angle of the proposed display. When no voltage is applied to the top electrode, the display shows wide viewing angle mode. On the contrary, this display shows narrow viewing angle mode. So, this device exhibits low operating voltage, high transmittance, and good viewing angle controllable characteristics.  相似文献   

13.
Abstract— The dynamic performance of displays is an important characteristic for multimedia applications. Motion‐picture response time (MPRT) has been used as an indicator of the dynamic performance of LCDs. This paper describes a comprehensive method of MPRT evaluation for the oblique viewing direction. By using a tilted camera configuration, the angular dependency of MPRT is investigated for the condition that the horizontally scrolling patterns are observed from the vertical direction. For each gray‐to‐gray transition, distinct changes in MPRT and the luminance profile of blur are observed.  相似文献   

14.
    
Fringe‐field‐switching (FFS) devices using liquid‐crystal (LC) with a negative dielectric anisotropy exhibit high transmittance and wide viewing angle simultaneously. Recently, we have developed an “Ultra‐FFS” thin‐film‐transistor (TFT) LCD using LC with a positive dielectric anisotropy that exhibits high transmittance, is color‐shift free, has a high‐contrast ratio in a wide range, experiences no crosstalk and has a fast response time of 25 msec. In this paper, the device concept is discussed, and, in addition, the pressure‐resistant characteristics of the devices compared with that of the twisted‐nematic (TN) LCD is discussed.  相似文献   

15.
    
Today's trend in automotive displays is toward more, larger, better, and flexible panels. The requirements for cars differ largely from consumer displays: Automotive displays have unique requirements in terms of optical performance, longevity in harsh environment, and production of 100,000s per year per model. Consumer electronics displays, however, set the pace and premium automotive panels have to follow in short time because of customer expectations despite long development cycles. Advanced procedures and measurements have to be applied like lifetime and ambient light. In order to reduce the effort in specifying and evaluating car displays in terms of optical performance, the German Flat Panel Forum has set common requirements for automotive validation. As standard measurement procedures are often less suitable for automotive evaluation, dedicated methods were developed like Black Mura, gamma and visual assessment of anti‐glare surfaces. Standardization reduces the effort along the automotive display value chain. People in future autonomous cars will spend more time watching displays than today, which must then be of highest optical performance. Design visions trend to present information – and not displays – to driver and passengers, which includes seamless displays and smart surfaces. A simple integration of flat displays into dashboards is no longer state‐of‐the‐art.  相似文献   

16.
    
Abstract— The high‐sensitivity pretilt‐angle measurement of liquid‐crystal displays, based on the modified crystal‐rotation configuration and the use of a common‐path heterodyne interferometer, is proposed. In this technique, environmental disturbance and surface reflection are eliminated to a large extend, thus providing advantages for both constructing a simple‐optics measurement system and achieving fast measurement with high accuracy and sensitivity.  相似文献   

17.
    
Abstract— Methods to reduce the power dissipation and supply voltage of LCD drivers for several line‐by‐line addressing techniques (viz., addressing based on Hadamard matrices, diagonal matrices, and wavelets) are proposed, based on the analysis and estimation of power dissipation in the drivers. Power dissipation, supply voltage, number of time intervals required to address the display, and maximum number of voltage levels in the addressing waveforms of these techniques are compared with that of the Successive Approximation Technique.  相似文献   

18.
    
Abstract— By using a new pixel design and a novel driving scheme that adds a bias electrode and a bias TFT to the ordinary pixel structure, a high‐contrast‐ratio and wide‐viewing‐angle LCD mode, refered to as the biased vertical‐alignment (BVA) mode, has been sucessfully developed. Compared to the published data on the PVA and MVA modes, the BVA mode has a distinct advantage of lower manufacturing cost due to the elimination of a lithographic process step that forms either ITO cuts or protrusions on the color‐filter substrates. The BVA mode requires ITO cuts on the TFT substrate similar to that for the PVA and MVA modes. The 15‐in. BVA‐mode XGA prototype exhibits a high contrast ratio of 1200:1 and high cell transmittance of 4.3%.  相似文献   

19.
    
Abstract— An overdrive technology was developed and is widely used to diminish motion blur in LCDs. To store a previous frame in the overdrive operation in a limited‐sized memory, simple image‐compression techniques are required. By considering the strong correlation of nearby pixels in natural images, a new 6:1 color‐image‐compression method based on directional prediction is proposed. Different from the directional prediction of intra‐coding in H.264/AVC, the predictable direction is determined beforehand to minimize the computation complexity. A simple content‐adaptive quantization and bit‐streaming method, which preserves image details and is free from blocking artifacts, is also proposed. The experimental results show that our proposed method outperforms the vector quantization block truncation coding method with an average 3‐dB peak signal‐to‐noise ratio (PSNR) as well as the subjective quality in terms of blocking artifacts.  相似文献   

20.
    
We have successfully demonstrated a control device for a viewing angle that enables switching between two states, a wide‐viewing angle, and a narrow‐viewing angle. It is composed of a light‐transmitting portion formed with an array of optical micro‐rods and a shielding/transmitting changeable portion of cross stripes designed with electrophoretic material systems consisting of black particles and an optically transparent medium. When the black particles are fully dispersed in the optically transparent medium, the cross stripe portion plays the role of a non‐transmitting material as the shielding portion in a similar manner to a conventional viewing angle control film. When the black particles are completely gathered electronically to one side in the optically transparent medium, in contrast, the cross stripe portion filled by the optically transparent medium can transmit incident light. These functions allow us to select electrically either of two modes between a limited viewing angle and a non‐limited viewing angle. The optical properties for the limited viewing angle mode were +/?30° of the visible angle and 50% of the transmittance, and the one for the non‐limited viewing mode was 58% of the transmittance. The response time from the narrow‐viewing angle to wide‐viewing angle was 1 s at 20 V of applied voltage.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号