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This paper proposes a color characterization model for predicting colorimetric information of all types of displays with high accuracy. Light leakage from black pixels causes errors in colorimetric information. By considering it, the proposed color characterization model accurately estimates colorimetric information of the red, green, and blue subpixels independently. In order to verify the universality of the proposed model, we apply it to all types of displays, including the organic light-emitting diode display. In addition, we show that the proposed model is more accurate than two of the most commonly used models, namely, the piecewise linear assuming chromaticity constancy model and the piecewise linear assuming variation in chromaticity model.

This paper proposes a temperature-dependent behavioral circuit model to predict the optical char- acteristics of an active-matrix liquid crystal display with a fringe-field switching (FFS) mode. The optical responses of liquid crystal displays (LCDs) are strongly affected by their ambient temperature. We optimized the time-constant parameters that describe the movement of liquid crystal molecules so that simulated optical responses of FFS LCD provide the best fit to the measured responses over the temperature range of 0 to 50°C. It is found that these time-constant parameters have a linear relationship with the ambient temperature, which enables the prediction of optical responses at any given temperature. The simulation results of the transient responses show an excellent match with the measured results regardless of the ambient temperature. © The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI. (DOI: 10.1117/1.OE.54.9.093104)

This paper proposes an adaptive charge sharing (ACS) method for reducing power consumption in liquid crystal displays (LCDs). Our ACS method involves calculating the power consumption of all data lines assuming the charge is shared and analyzing the analog characteristics of the data transitions. With conventional CS, charge is shared between data lines only when the polarities of data signals change. Our ACS method selectively shares charge even when no polarity change occurs, but only if CS provides an overall reduction in power consumption. To compare the performance of ACS and conventional CS, we applied the ACS method to common inversion methods, namely, column, two-dot, and Z inversion. Our simulation results demonstrate that the ACS method can effectively reduce power consumption, especially with the column and Z inversion methods. The average power consumption of the ACS method with column and Z inversion was 87.7% and 84.7%, respectively, of the conventional CS power consumption.

We propose an overdrive (OD) technology to precisely compensate for the temperature-dependent response characteristics of liquid-crystal displays (LCDs). The optical responses of LCDs are highly dependent on ambient temperature. After analyzing the optimized OD values, the new OD technology uses simple calculation logic instead of bulky OD lookup tables to obtain OD values of rising transitions over a wide range of ambient temperatures. We also show that it is possible to automatically adjust the optimum OD values depending on the ambient temperature. The results show that the proposed OD technology can improve motion image quality without any motion artifacts regardless of the ambient temperature. We expect that our proposed OD technology will ensure that LCD products have a consistent motion image quality regardless of the ambient temperature without any increase in cost.

This paper reports transient response characteristics of active-matrix organic light emitting diode (AMOLED) displays for mobile applications. This work reports that the rising responses look like saw-tooth waveform and are not always faster than those of liquid crystal displays. Thus, a driving technology is proposed to improve the rising transient responses of AMOLED based on the overdrive (OD) technology. We modified the OD technology by combining it with a dithering method because the conventional OD method cannot successfully enhance all the rising responses. Our method can improve all the transitions of AMOLED without modifying the conventional gamma architecture of drivers. A new artifact is found when OD is applied to certain transitions. We propose an optimum OD selection method to mitigate the artifact. The implementation results show the proposed technology can successfully improve motion quality of scrolling texts as well as moving pictures in AMOLED displays.

This paper proposes a parallax barrier with an elliptical pattern that reduces the cross talk caused by light leakage from adjacent subpixels in autostereoscopic three-dimensional (3-D) displays. To find the optimum size of the elliptical barrier pattern, the relationship between the reduction of the light leakage and that of the luminance is analyzed. In addition, we analyze the relationship between the cross talk and the luminance. By using these relationships, we propose an optimum size of the ellipse. An autostereoscopic 3-D display with the elliptical barrier is compared with 3-D displays with the slanted barrier and the rectangular one. The measured cross talk of the slanted-type 3-D display whose pixel size is 98×294 μm was 57%. However, the cross talk of the ellipse-type 3-D display was 32% at the similar luminance condition when the minor and major axes are 92 and 278 μm, respectively. For generalization, we investigate autostereoscopic 3-D displays with different pixel sizes and different viewing distances. We find the optimum area of the ellipse is 70% of the subpixel area to reduce the cross talk.

We propose a new three-dimensional (3-D) crosstalk minimization method for the active shutter glasses-type 3-D liquid crystal displays (LCD) television (TV). The crosstalk was reduced from 43% to 10% on average with the proposed technology. Furthermore, we propose a user-friendly method to reduce the 3-D crosstalk without any measurement equipment, which enables consumers to make their TVs crosstalk free. It is found that the results of the proposed crosstalk minimization method and user-friendly method are matched well. Thus, 3-D TV consumers can easily minimize the 3-D crosstalk with their eyes only.

A new technology is presented that enables liquid crystal displays (LCDs) to have temperature-independent characteristics. This work shows how severely the color image quality of LCDs is affected by the ambient temperature change in addition to showing how the ambient temperature considerably affects the motion image quality of overdriven LCDs. Transmittance-voltage curve-shifting technology is proposed to compensate for the color change owing to temperature change. This new technology reduces a half-maximum luminance error from 24% to 6% over the temperature range from 0°C to 50°C. The linear overdrive (OD) technology over the wide temperature is presented to overcome the temperature-dependent characteristics of LCDs. With this technique, the distribution of the OD error is reduced by 65%. The color and motion image quality of LCDs can be kept the same with these techniques, regardless of temperature.

We propose a precise circuit model to estimate transient optical responses of an active-matrix liquid crystal display (AMLCD). Liquid crystal (LC) molecules in the pixel is behaviorally modeled by using the first-order system that is described by Verilog-A. Capacitance-voltage (C-V) characteristics of a pixel determine the accuracy of the dynamic responses. Measuring C-V characteristics is impossible because pixels are driven by switching transistors in the AMLCD. We propose a method to obtain the C-V data from natural optical responses. Estimated optical responses based on the C-V data extracted by our proposal show more accurate results than those based on C-V data obtained by using transmittance-voltage data. It is demonstrated that our behavioral model enables us to predict very accurate transient responses, which makes it possible to design LCD products with lower costs.