A new compact projection display has been developed using light valves based on a 2-inch diagonal low-temperature poly-Si TFT reflective XGA array and polymer dispersed LC-mode, 120-W ultrahigh-pressure short-arc lamp (UHP lamp), and simple optical components. Luminous flux of 1400 ANSI-lm, contrast ratio of 85, and the illuminance homogeneity of 90% were achieved. Simulation by basic optical theory in concentrators and experiments with a simplified reflective-type polymer dispersed LC-mode light valve indicates that the performance could be improved in future up to a luminous flux of 1600 ANSI-lm with contrast ratio of more than 150.
We have developed an optical system using three D-ILATM (Direct image Light Amplifier) panel modules (reflective type liquid crystal device) for a projection display that produces extra-bright, high-resolution, images having high contrast ratio and good color reproduction. It uses some dichroic mirrors for color separation and one cross dichroic prism for color combination. The polarizing performance of these optical elements enables it to achieve such good color reproduction.
Field-sequential color projectors have the advantage of high resolution, but they cause color breakup. It is supposed that this phenomenon is observation of clear color by the divided color image, which occur by rapid eye movements, even if the frame frequency is beyond the critical fusion frequency (CFF). To explain the mechanism of the color breakup, we made an apparatus that can present the divided image of each color field to the retina by a moving edge with high retinal velocity, in condition without eye movement. If the discrimination of the color depends on the divided color width, the frame frequency is linear to retinal velocity. The threshold frequency, however, saturated when the retinal velocity was 100 to 200 deg/s, and then it increased again. Moreover, the appearance of the divided color image changed from clear colors to pale colors. These results suggest that there are complex mechanisms of the occurrence of the color breakup.
A 17-in. video rate full color Ferroelectric Liquid Crystal Display (FLCD) with 720×916 dots, using τ-Vmin mode was developed. The full color moving images with 256 gray levels for each color was displayed by the digital gray scale method combining 2 bits spatial dither and 4 bits temporal dither. The response speed of FLC material is very fast (12μs/line) and the 4 bits temporal dither with video rate scanning was realized. The FLCD shows a contrast ratio of 60 : 1, a wide viewing angle due to the in-plane switching, and strong shock stability (20 kg/cm2) due to the spacer walls structure. This paper presents a high potential of FLCD for the large-size direct-view video-rate full-color simple-passive-matrix flat panel display.
We have been developing a thermally writable and electrically erasable rewritable medium utilizing guest-host (G-H) polymer dispersed liquid crystal (PDLC) films. The PDLC rewritable medium can display bistable images using the memory effect of smectic A liquid crystal (SmA LC). It uses the difference in scattering of the SmALC layer with homeotropic and focal conic alignments. Dichroic dyes are added into SmA LC to make a G-H system with improved contrast.
The picture quality of a liquid crystal display (LCD) significantly changes with the observation angle. One of factors involved is the color change of an image. This study aimed to clarify the influence of color reproduction range on picture quality. In the experiment, “saturation decrement ratio” was newly defined for each of the primary colors, which restricted the change in color reproduction range on a display. Picture quality was measured by subjective evaluation of images reproduced with different saturation decrement ratios. We found that picture quality decreased monotonically with decreasing color saturation. When the saturation of a primary color was independently decreased, the decrease in picture quality was largest for a decrease in the saturation of blue. Moreover, the decrease in picture quality was larger than that of blue if the color temperature was kept constant.
The stereoscopic displays that do not require observers to wear special spectacles are required in various fields, but most of the traditional methods are complex and expensive. We have developed a very reasonable and unique stereoscopic display using a pair of 2 D-displays, a water tank, and sheet glasses. The display system uses total reflection, rather than the space or time-divided methods, so it provides, high-resolution flicker-free stereo images.
We evaluated the visual fatigue in a binocular disparity type 3-D display system. Currently, 3-D display systems are spreading to various applications such as medical equipment and amusement games. However, they are known to cause visual fatigue in users. To evaluate this fatigue, we focus on the mismatching between convergence and accommodation, since it is a major problem with binocular disparity type 3-D displays. This paper reports the basic idea of evaluation, subjective assessment for this evaluation and current result of assessment. For this subjective assessment, we use a newly-developed binocular disparity 3-D display system with a compensation function for accommodation. Because this equipment only allowed us to compare the terms of the mismatching itself, the evaluation is more accurate than similar previous works. As a result of this measurement, we were able to confirm the effectiveness of the indexes and the method of measurement, and could also quantitatively explain the influences of the mismatching on the accommodation function.
We discuss the optimization of filter coefficients in a tree-structured bank with allpass polyphase filters for subband image coding. First we show that the impulse response length and cutoff characteristics of the filter bank have a tradeoff relationship in terms of coding performance. Then we propose a method of designing a bank by minimizing the product ΔnΔw between the time and bandwidths of subband filters. Amplitude responses of the designed subband filters nearly approximate Gaussian functions and their ΔnΔw are little larger than the lower bound of the uncertainty principle. Coding simulations show that the coding performance of the designed bank compares favorably with that of image-optimized banks.
The induction field model can be used to explain Kato's experimental psychological results of objective evaluation of handwritten character quality. A lot of psychological experiments have been carried out to find the recognition process and the features of handwritten characters. However, there is no mathematical model that can explain the results of psychological experiments for handwritten characters. Recently, the focus has been on dynamics as the concept that explains the recognition process. Furthermore, the induction field model based on dynamics can explain some psychological experimental results for some artificial patterns, letters, and ambiguously shaped patterns. This paper shows that this model can explain psychological experimental results for handwritten character quality.