Motion‐blur characterization on liquid‐crystal displays

Abstract— In this paper, several methods to characterize motion blur on liquid‐crystal displays are reviewed. Based on the assumptions of smooth‐pursuit eye tracking and one‐frame temporal luminance integration, a simple algorithm has been proposed to calculate the normalized blurred edge width (N‐BEW) and motion‐picture response time (MPRT) with a one‐frame‐time moving‐window function to LC temporal step response curves. A custom measurement system with a fast‐eye‐sensitivity‐compensated photodiode has been developed to characterize motion blur based on LC response curves (LCRCs). MPRT values obtained by using the algorithm mentioned above and those from the smooth‐pursuit‐camera methods agree. Perception experiments were conducted to validate the correspondence between the simulated results and actual perceived images by the human eyes. In addition, the insufficiency of MPRT to evaluate motion blur on impulse‐type light‐generation LCDs, by analyzing the measurement results of a scanning backlight LCD, is discussed.     

Evaluation of liquid‐crystal‐display motion blur with moving‐picture response time and human perception

Abstract— The moving‐picture response time (MPRT) for measuring liquid‐crystal‐display (LCD) motion blur was studied by several organizations in 2001. To determine the LCD motion blur that humans perceive, subjective evaluation experiments using the method of adjustment was conducted to find a strong correlation between perceived motion blur and extended blurred edge time (EBET) of the MPRT measurements. MPRT thus clearly indicates the degree of which humans perceive motion blur.     

A straightforward method of measuring MPRT using LC test cells

Abstract— A simple method based on integration over time to measure motion‐picture response time (MPRT) has been developed. Liquid‐crystal response time (LCRT) alone cannot express the motion blur perceived by the observer; one must also take into account the transition between intermediate gray levels and the sample‐and‐hold effect. The method shows similar results to other previously reported methods based on temporal integration, while being simpler and more straightforward. Indeed, just monopixel test cells are required for measuring MPRT. This method can be used for comparison between different materials, alignments surfaces, or other manufacturing details with no need of fabricating the whole LCD structure. Nevertheless, the method could also be used for characterization of commercial displays with major changes. A comparison of MPRT values for three different liquid‐crystal materials is presented in this work. The behavior of the MPRT parameter in the case of an ideal liquid‐crystal material with an LCRT equal to zero has also been studied. The results obtained for this material have been used as a reference to establish comparisons with real materials.     

A high image quality organic light‐emitting diode display with motion blur reduction for ultrahigh resolution and premium TVs

In this paper, we present a high image quality organic light‐emitting diode (OLED) display with motion blur reduction technology. Our latest work includes driving method that reduces motion blur using an adaptive black data insertion, brightness compensation technology, the simple structure pixel with low capacitance coupling for horizontal noise, and the multifunction integrated gate driver. The moving picture response time (MPRT) value of the OLED display panel with a fast response time was significantly affected by the frame frequency and the compensation driving method. The MPRT value of the large‐size OLED display panels was significantly decreased by using the integrated gate driver circuit with an MPRT reduction method. The decrease in the MPRT value originated from the turning of the emitting pixels off in advance resulting from providing black data. The integrated gate drivers were designed to achieve the normal display, the black data insertion, and the compensation mode. The MPRT value of the 65‐in. ultrahigh‐definition (UHD) OLED panels was decreased to 3.4 ms by using an integrated gate driver circuit. The motion blur of large‐size OLED display panels was significantly reduced due to a decrease in the MPRT value.     

Moving‐picture response time (MPRT) of LCDs for the oblique viewing direction

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.     

Comparisons of motion‐blur assessment strategies for newly emergent LCD and backlight driving technologies

Abstract— Compared to the conventional cathode‐ray‐tube TV, the conventional liquid‐crystal TV has the shortcoming of motion blur. Motion blur can be characterized by the motion‐picture response‐time metric (MPRT). The MPRT of a display can be measured directly using a commercial MPRT instrument, but it is expensive in comparison with a photodiode that is used in temporal‐response (temporal luminance transition) measurements. An alternative approach is to determine the motion blur indirectly via the temporal point‐spread function (PSF), which does not need an accurate tracking mechanism as required for the direct “spatial” measurement techniques. In this paper, the measured motion blur is compared by using both the spatial‐tracking‐camera approach and the temporal‐response approach at various backlight flashing widths. In comparison to other motion‐blur studies, this work has two unique advantages: (1) both spatial and temporal information was measured simultaneously and (2) several temporal apertures of the display were used to represent different temporal PSFs. This study shows that the temporal method is an attractive alternative for the MPRT instrument to characterize the LCD's temporal performance.     

Moving‐image simulation for high‐quality LCD TVs

Abstract— A simulation system incorporating pixel response and eye‐trace integration was developed to evaluate the moving‐image performance of high‐quality LCD TVs. A simple formula was derived for moving‐edge simulation, which can be used to evaluate the visual effects of arbitrary response waveforms. A model of exponential decay with dynamic time constants is proposed for the LC response to perform moving‐image simulation. The model was used to evaluate the visual effects of various motion‐blur‐reduction techniques. Six different motion‐blur‐reduction techniques were evaluated in terms of their visual effects. Among them, three basic techniques show certain defects, which are further analyzed by simulation. The other three advanced techniques show excellent performance, and, therefore, are recommended for use in high‐quality LCD TVs.     

Mathematical modeling of the LCD response time

Abstract— Techniques to reduce LCD motion blur are extensively used in industry and they depend on an inherent LCD parameter: response time. However, normative response time is not a sufficient reference to improve LCD performance and all the gray‐to‐gray response‐time quantities are required to obtain good improvement. However, measuring and gathering all the gray‐to‐gray transitions takes an excessive amount of time. Consequently, we propose a novel LCD model to simulate as well as compute gray‐to‐gray transitions (response time and behavior) from a reduced measurement set in order to decrease the response‐time measurement.     

Novel 120‐Hz TFT‐LCD motion‐blur‐reduction technology with integrated motion‐compensated frame‐interpolation timing controller

Abstract— Samsung has developed a high‐resolution full‐HD (1920 × 1080) 120‐Hz LCD‐TV panel using a novel pixel structure and a motion‐compensated frame‐interpolation (McFi) single‐chip solution. Our latest work includes launch of a 70‐in. full‐HD panel, the world's largest LCD TV in mass production, with a 120‐Hz frame rate. A serious problem involving the charging time margin has been completely overcome through the use of a new alternative 1G‐2D pixel structure and a new driving scheme. Compared with conventional dot‐inversion driving, our new dot‐inversion method, which is a spatial averaging technique, can save power because the column drivers are operated using vertical inversion driving. In addition, McFi, which merges individual ME/MC and timing‐controller (TCON) ICs and memories, has been developed and applied in a mass‐production product for the first time ever. The McFi solution provides 120‐Hz driving with the lowest possible system cost. Motion‐picture response time (MPRT) has been reduced from 1 5 to 8 msec. Moreover, for the case of 24‐Hz film source mode, motion judder has been completely eliminated. As a result, a lineup consisting of 40‐, 46‐, 52‐, 70‐, and 82‐in. LCD‐TV panels with high quality and manufacturability has been made possible.     

A dual‐cell‐gap transflective liquid‐crystal display with identical response time in transmissive and reflective regions

Abstract— A dual‐cell‐gap transflective liquid‐crystal display (TR‐LCD) with identical response time in both the transmissive and reflective regions is demonstrated. In the transmissive region, strong anchoring energy is used to decrease the response time, while in the reflective region, weak anchoring energy is used to increase the response time. And overdrive voltage technology is adopted to make the response time identical in both the transmissive and reflective regions. The device structure and operating principle of the TR‐LCD was analyzed, the anchoring energy in the transmissive and reflective regions was designed, and the response time and electro‐optic characteristics of the TR‐LCD was calculated. The simulated dual‐cell‐gap TR‐LCD demonstrated good performances.     

Color management of reflective‐type LCDs in terms of adaptation of the human visual system to light‐source variation

We have investigated the color management, in terms of the color adoption property of the human visual system, of a reflective‐type TFT‐LCD (R‐LCD). Since the R‐LCD depends on ambient light as the light source, it is expected that the colorimetric color on the R‐LCD must be changed if the source of the ambient light is changed. However, due to the adaptation property of the human visual system, the eye does not perceive colorimetrically corrected colors as the same color even for an R‐LCD. In this research, first, we conducted a subjective experiment to obtain the RGB code value that is required in order to display a corresponding color on the R‐LCD under varying ambient‐light conditions. The result of the experiment shows that the corresponding color of the experimental results was reasonably approximated by the color obtained by using the von Kries model. Secondly, we proposed a color‐compensating mechanism that is described as a cascaded simple 3 × 3 linear matrix. Actual colors displayed are adjusted according to the ambient light. The evaluation of the picture quality of the R‐LCD showed that the proposed model is effective.     

Effect of moving pictures on visual task performance and fatigue using 4K OLED and LCD TVs

This study compared the effects of 4K organic light‐emitting diode (OLED) and liquid‐crystal display (LCD) TVs on human visual task performance and fatigue when viewing moving pictures. In experiments conducted, subjects were asked to locate 35 icons among a total of 276 on‐screen icons at four moving picture speeds. From the results obtained, it was determined that OLED TVs (emissive type) exhibit superior characteristics for hit rate and false alarm rate compared with LCD TVs (non‐emissive‐type). The evaluation results of a simulator sickness questionnaire administered to ascertain fatigue levels also indicated that OLED TVs induce relatively little fatigue at fast‐moving picture speeds of 10 ppf or more compared with LCD TVs. Thus, this study confirms that OLED TVs, given their ultrafast response time characteristics, are superior in terms of moving picture images to LCD TVs.     

A reduction method of dynamic false contour utilizing the frame‐rate‐control method with suppression of the side effect on PDPs

Abstract— The plasma‐display panel (PDP) is a type of flat‐panel display that can display a high‐quality image. However, when moving images are displayed, annoying disturbances such as false contour noise occurs. This noise is called dynamic false contour (DFC). To achieve a higher‐quality image, DFC has to be reduced. Therefore, a new method to reduce DFC is proposed. To find a way to reduce DFC, a new evaluation value for it has been defined: the evaluation value of dynamic false contour (EVDFC). This value is defined on the basis of a person's subjective evaluation. By applying this value, the cause that generates DFC can be identified. On the basis of these studies, a new method for reducing DFC by applying frame‐rate control (FRC) with suppression of the side effect is proposed. This improved method can be used to provide high‐quality images.     

Digital time‐modulation pixel memory circuit in LTPS technology

Abstract— A digital time‐modulation pixel memory circuit on glass substrate has been designed and verified for a 3‐μm low‐temperature polysilicon (LTPS) technology. From the experimental results, the proposed circuit can generate 4‐bit digital codes and the corresponding inversion data with a time‐modulation technique. While the liquid‐crystal‐display (LCD) panel operates in the still mode, which means the same image is displayed on the panel, a data driver for an LCD panel is not required to provide the image data of the frame by the proposed pixel memory circuit. This pixel memory circuit can store the frame data and generate its corresponding inversion data to refresh a static image without activating the data driver circuit. Therefore, the power consumption of a data driver can be reduced in the LCD panel.     

Fast‐response liquid‐crystal displays using crossed fringe fields

Abstract— A fast‐response and wide‐view liquid‐crystal display (LCD) using the crossed fringe‐field‐switching (CFFS) mode is proposed, where the fringe‐field electrodes exist on both the top and bottom substrates. The bottom fringe field is used to turn on the LC directors and the top fringe field is used to assist in the LC decay process. The decay time is reduced by ～2× compared to that of the conventional FFS mode between the full bright and dark states, and more than a 2× improvement is obtained for other gray‐scale transitions. This CFFS mode also preserves the wide‐view characteristics as the conventional FFS mode. Its applications to LCD TVs and monitors for reducing image blur are addressed.     

High‐performance OCB‐mode field‐sequential‐color LCD

Abstract— Optically compensated bend (OCB) mode is a promising technology for future high‐quality display devices due to its wide viewing angle without gray‐scale inversion and color shift, fast response time, high contrast ratio, and wide temperature range. This paper summarizes the developments of the OCB mode and the optical performance of OCB‐mode field‐sequential‐color LCD.     

Reducing the memory of compression Feedforward driving for a new LCD controller

Abstract— The authors have studied a method of reducing the frame memory for signal processing used to improve the response time of liquid crystals. Compared with cases in which quantization is used, the compression Feedforward driving method, which reduces frame memory by applying an image‐compression technique, can effectively reduce the frame‐memory size. The study revealed that errors decrease by 6–10 dB or so if the image data was reduced to 1/3 by means of image compression. Based on the results of the study, the authors have developed a second‐generation LCD controller. With just one SDRAM unit, this LCD controller can produce almost ideal processing effects.     

TFT‐LCD driver IC with embedded non‐volatile memory for portable applications

Abstract— To improve the display quality and yield of the TFT‐LCD driver IC, non‐volatile multiple‐time‐programmable (MTP) memory, which consists of an EEPROM cell and our proposed sense amplifier and power control circuit (SP), was integrated into a TFT‐LCD driver IC. The proposed SP has a 30% smaller layout area and a 18% faster response time compared to that of the conventional SP. The proposed SP also has lower power consumption because it does not use a static current. The TFT‐LCD quality was also improved by tuning the characteristics of the driver IC and the panel with the VREF, OSC, and VCOM blocks, using non‐volatile MTP memory. When the display quality improved, the yield also improved, along with a reduction in the failure ratio of the display module, which consists of the driver IC and the panel. As a result, the TFT‐LCD driver IC with the non‐volatile MTP memory demonstrated improved display quality and a higher yield compared to conventional driver ICs without such a memory.     

Advanced level‐adaptive overdrive (ALAO) method applicable to full‐HD LC TVs

Abstract— In this paper, we report on the development of an advanced level‐adaptive overdrive (ALAO) method applicable to full‐HD LC TVs, which makes it possible not only to reduce the gray‐level response time to less than one fourth, but also to improve the S/N ratio for still images by 10 dB; and further to reduce the circuit cost for the LAO method to almost half that of the prior LAO circuit. We have applied the ALAO method to a full‐HD LC front projector with 1.84 Mpixels and a screen size larger than 100 in., and we obtained high‐quality full‐HD moving images.     

Fast‐response study of polymer‐stabilized VA‐LCD

Abstract— Polymer stabilization is introduced in VA‐type LCDs, and fast response time can be achieved along with a high contrast ratio.¹ A small amount of reactive monomer is mixed with liquid crystal and forms a polymer layer above the alignment layer by using a UV process. The pre‐tilt angle of the liquid crystal is stabilized, and a faster response time can be realized when the bias pre‐tilt angle from 90° is increased. The properties of reactive monomers and liquid crystal and the conditions of the UV process were studied. Based on the application of the proper monomer and LC, and an optima UV process, a 65‐in. 240‐Hz full‐HD TFT‐LCD, with a faster response time and high contrast ratio, has been developed.