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1.
    
Abstract— Spatio‐temporal color displays have higher transmission and resolution than conventional LCDs, but suffer from color breakup. In this paper, a 120‐Hz display with two‐color filters and two‐color fields is described and the amount of color breakup is compared with that of a 180‐Hz full‐color‐sequential display with no color filters and three‐color fields. The results indicate that color breakup in a color‐filterless display is annoying, whereas it is just visible in displays with two‐color filters even though the refresh rate is much lower.  相似文献   

2.
    
Abstract— The color performance, including color gamut, color shift, and gamma curve, of a multi‐domain vertical‐alignment (MVA) liquid‐crystal display (LCD) using an LED backlight are calculated quantitatively. Simulation results indicate that an LED backlight exhibits better angular color uniformity and smaller color shifts than a CCFL backlight. Color gamut can be further widened and color shift reduced when using a color‐sequential RGB‐LED backlight without color filters, while the angular‐dependent gamma curves are less influenced using different backlights. The obtained quantitative results are useful for optimizing the color performance and color management of high‐end LCD monitors and LCD TVs.  相似文献   

3.
    
An index that can predict the perceptual visibility of color breakup for varying image content is valuable in field sequential color displays, whereas the current indices are usually for fixed patterns. To solve this problem, an image database containing 25 diverse reference images and 125 test cases with various color breakup visibility was first established. Next, visual experiments using a 240‐Hz liquid crystal display were performed to acquire the subjective color breakup scores of the test cases. A theorem based on visual saliency theory was proposed that the color breakup perception is mainly determined by the image regions with visual saliency values higher than a certain threshold, called the dominant visual saliency regions. A computational model based on this theorem was developed to obtain objective color breakup scores of the test cases from retinal images with and without color breakup. An analysis of the objective and subjective results revealed a Pearson linear correlation coefficient as high as 0.82, which matches the top‐level image quality assessment algorithms. Finally, the proposed color breakup index was used to benchmark against several mainstream field sequential color algorithms to determine their performances in color breakup suppression.  相似文献   

4.
    
Abstract— The proposed liquid‐crystal and backlight (LC/BL) algorithm presents the dynamic field‐sequential‐color (D‐FSC) algorithm to reduce the color‐breakup (CBU) effect without greatly increasing the subframe rate. The D‐FSC algorithm can intelligently select one adequate color sequence from multiple color sequences according to the image data. In other words, the scope of CBU suppression of the proposed LC/BL algorithm is more extensive than other conventional FSCs. Simulation results show that the CBU suppression can be improved substantially by the proposed evaluation equation.  相似文献   

5.
    
Abstract— Field‐sequential color (FSC) is a potential technique for low‐power liquid‐crystal displays (LCDs). However, it still experiences a serious visual artifact, color break‐up (CBU), which degrades image quality. Consequently, the “Stencil Field‐Sequential‐Color (Stencil‐FSC)” method, which applies local color‐backlight‐dimming technology at a 240‐Hz field rate to FSC‐LCDs, is proposed. Using the Stencil‐FSC method not only suppressed CBU efficiently but also enhanced the image contrast ratio by using low average power consumption. After backlight signal optimization, the Stencil‐FSC method was demonstrated on a 32‐in. FSC‐LCD and effectively suppressed the CBU, which resulted in more than a 27,000:1 dynamic contrast ratio and less than 40‐W average power consumption.  相似文献   

6.
    
Abstract— A two‐dimensional array consisting of dye‐doped reflection‐mode holographic‐polymer‐dispersed liquid crystal (H‐PDLC) lasers with alternating pitch lengths is presented. These post structures each reflect at a narrow bandwidth of light. The addition of laser dye to the H‐PDLC system allows for the generation of laser emission at the edge of the reflection band, or photonic band gap. In patterning these H‐PDLC post structures, a narrow‐linewidth patterned emissive color film is realized. The potential of such films and their implication in the display industry is discussed. In creating a three‐color array, an active emissive color film could replace the backlight and color filter components within the display. Such a patterned system would possess a wide color gamut, through spatial color synthesis, formed by narrow‐linewidth lasing structures with well‐defined wavelengths of emission.  相似文献   

7.
    
Based on the measured temporal luminance behavior of each field, the perceived color breakup (CBU) artifact for moving block on a field sequential color display is simulated and predicted. The prediction accuracy is evaluated by a perceptual experiment on a 240 Hz liquid crystal display. The results show a perfect matching between the simulation and the subjects' actual visual experience. The simulation also works well when motion compensation is applied. It is validated by another perceptual experiment that a perfect or a near‐perfect compensation degree can suppress CBU significantly in field sequential color system. CBU of nature image was also simulated and reproduced for both stable and pulse backlight by using this model, which could be rather valuable for the further development of CBU metrics.  相似文献   

8.
    
Abstract— Two newly derived characterization models for a liquid‐crystal (LC) display have been tested for five LC‐based displays. Data measured from a series of test colors indicated that all LC‐based displays showed similar characteristics, including an S‐shaped tone curve and poor channel chromaticity constancy. Because they include a hyperbolic function in their definition, the models do not have analytical inverses, and so iterative mathematical techniques are applied. It was shown that a new characterization model based on a hyperbolic function fits the tone curve very accurately with only four coefficients per channel for any type of LCD. In addition, it was also shown that the first derivative of the function provides a means of accurate correction of the chromaticity variation.  相似文献   

9.
    
Abstract— Electrowetting‐based displays have been successfully demonstrated in reflective mode, showing video capability and high optical performance. However, because this technology is based on a high‐efficiency optical switch operating between a light‐absorbing state and a light‐transmitting state, the technology lends itself naturally to a transmissive mode enabling a complete range of applications. This paper describes the first active‐matrix full‐color transmissive electrowetting displays including its main technical and system aspects. Two architectures have been demonstrated: one uses color filters, the other field‐sequential‐color illumination. The paper also introduces alternative concepts for more efficient color transmissive electrowetting displays with multiple absorbing layers.  相似文献   

10.
    
Abstract— An intrinsic half‐V‐mode ferroelectric liquid‐crystal display (FLCD) exhibiting a high contrast ratio (300:1), owing to defect‐free gray‐scale capability, with a high response speed (τ ? 400 μsec) and good switchability with TFTs, has been developed. Furthermore, this FLCD features high‐temperature reliability owing to the use of a special hybrid alignment technique. We successfully fabricated an active‐matrix poly‐Si TFT field‐sequential full‐color (FS FC) LCD with XGA specifications and a 0.9‐in. diagonal using a half‐V‐mode FLCD and an RGB light‐emitting‐diode (LED) array microdisplay. It is shown that the fabricated active‐matrix FS FCLCD exhibits good moving‐image performance with high full‐color display capability.  相似文献   

11.
    
Abstract— A color‐filter liquid‐crystal‐on‐silicon (CF‐LCOS) microdisplay that integrates color filters on silicon for color will be presented. The color‐filter process on silicon was optimized to achieve fine resolution and precise alignment of the color filters on the pixel array, good adhesion to the silicon suface, and a flat surface for the liquid‐crystal cell assembly. Important optical and electrical parameters of the color filters were extracted to establish an electro‐optical model of the CF‐LCOS microdisplays for device simulation. Thermal, chemical, and light‐stability characterizations were performed to ensure the stabilty of the color filters and CF‐LCOS microdisplays. With color CF‐LCOS microdisplays already available, the projection or viewing optics is greatly simplified. This CF‐LCOS microdisplay is ideal for near‐to‐eye displays because of its low‐power consumption and compactness. The CF‐LCOS microdisplay could also withstand medium light illumination for medium‐sized projectors. A single‐panel projector based on one CF‐LCOS microdisplay of 1280 × 768 × RGB resolution was demonstrated.  相似文献   

12.
    
Abstract— Field‐sequential projection displays exhibit a phenomenon of color breakup (Rainbow effect). This is considered to be a disturbing artifact with negative marketing impact. The results of a psychophysical experiment comparing the visibility of the phenomenon in RGB and multi‐primary displays is described. Surprisingly, it is found that color breakup in color‐sequential projection displays with five primaries is equally (for 75 Hz) or less (for 105 Hz) visible than in similar displays with three primaries (at 180 Hz), despite the lower refresh rates.  相似文献   

13.
    
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   

14.
    
Abstract— We have developed a process to fabricate optical components, such as a lens, prism, or diffuser, directly on to a glass substrate. Processes include precision mastering by diamond cutting and multi‐layer photopolymer (2P) molding to realize flat surfaces and the integration of multiple components with an alignment within a few micrometers.  相似文献   

15.
    
Abstract— Liquid‐crystal‐display backlight units have developed in their conventional configuration into very efficient and uniform components that allow the display to present a high‐quality image to the user. Developing the backlight unit itself further faces a challenge of diminishing returns to the investment in innovation. A system‐level redesign is required for the entire display module, and diffractive alternatives to the backlight design can allow a more‐energy‐efficient design for the display. This review concentrates on small‐to‐medium displays because diffractive backlight studies have also centered in this class of displays. The state of the art of backlight design is summarized and the motivation for energy‐efficient system design is outlined. The theoretical basis of diffractive backlights is given, and key research studies in the area of diffractive backlights are reviewed. Finally, a discussion on the performance and future outlook of diffractive backlights completes the paper.  相似文献   

16.
    
Abstract— The display backlight unit (BLU) is the most power‐consuming subunit in mobile liquid‐crystal displays. The state‐of‐the‐art BLUs utilize scattering, refractive, and reflective microstructures to generate a uniform distribution of white light through the display. More effective means of transmitting light through the display color filters could be obtained by using diffraction, but previously proposed diffractive backlights do not fully utilize all the possibilities to design gratings effectively for optimal color separation and outcoupling. This paper presents a new pixelated diffractive backlight grating array as an approach for overcoming these obstacles in BLU design. A model array was fabricated to couple out red, green, and blue primary colors from the respective subpixel locations. The results show that it is possible to manufacture such an array and that the light couples out as intended, giving a starting point to design mobile‐display modules with low light‐transmission losses.  相似文献   

17.
    
Abstract— A spatially and temporally scanning backlight consisting of ten isolated micro‐structured light guides has been developed to be combined with a fast‐response optically‐compensated‐bend‐mode field‐sequential‐color LCD in which the liquid‐crystal cell does not contain color filters. The sequential fields of three primary colors are generated by illumination of the red‐, green‐, and blue‐light‐emitting diodes, each illuminating for one‐half of the field, resulting in a luminance of 200 cd/m2 for the LCD. The effect of light leakage between the blocks in the scanning backlight in field‐sequential‐color applications was measured and will be described.  相似文献   

18.
In order to achieve the standard red, green, and blue (sRGB) standard color gamut in color liquid crystal display and improve the image quality, the impact of the backlight and color filter spectrum on module's chroma was simulated and analyzed. The color gamut was enhanced by adjusting and optimizing the two parts of spectrums of LED backlight and color filter and by using red and green phosphor LED backlight to match the new color filter with an appropriate thickness. Experimental results show that: When the thickness of color filter is 2.2 µm, National Television System Committee color gamut increases from 65.3% to 74.9%, and sRGB matching rate enhances from 83.2% to 100%, achieving a full coverage of the sRGB standard color gamut, the transmittance of white light reaches 28.1%. Also, it is verified that shifting the peak position of the backlight and color filter spectrum to purification direction, as well as narrowing its half‐width can upgrade the color gamut. Meanwhile, the thicker the thickness of color filter is, the wider color gamut it has, based on the same pigment material.  相似文献   

19.
    
Conventional displays use at least three primaries for full‐color image reproduction. In this contribution, the reproduction of color images using an LCD system with two local dynamic primaries, based on a segmented backlight, will be discussed. The two primaries are chosen to minimize color error by means of total least squares. Simulation results indicate quite good color reproduction for a large set of video data even with a limited number of backlight segments. A statistical analysis of this video content shows that excellent color reproduction (?u′v′ < 0.020 for more than 99.0% of the pixels per frame) can be achieved for 74.2% of the frames using 9216 backlight segments.  相似文献   

20.
    
Abstract— In conventional LCDs, the backlight is set to maximum luminance regardless of the image. For dark scenes, this approach causes light leakage and power waste. Especially, light leakage in dark scenes degrades the contrast ratio of LCDs; to circumvent this problem, local‐dimming systems have been proposed. In these systems, the LED backlight is divided into several local blocks and the backlight luminance of each local block is controlled individually, and pixel values are adjusted simultaneously according to the luminance profile of the dimmed backlight. In this paper, a method of determining the LED backlight luminance of each local block depending on the image is proposed; this method significantly improves the image quality of LCDs. First, we introduce methods of quantifying light‐leakage at dark gray levels and clipping at bright gray levels. Then, the proposed method to determine the dimming duty, which controls the LED backlight luminance by compromising between these two measures, was derived. The proposed algorithm preserves the original image with little clipping distortion and effectively reduces light leakage.  相似文献   

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