We developed an ultra-thin RGB-LED backlight (BL) system for 52"and 65" LCD-TVs. It is constructed by combining the structures of the direct-lighting and edge-lighting systems. The system can be used to control luminance both spatially and temporally with pulse-width-modulation-driven RGB-LEDs so that it can easily support local dimming techniques of an LCD-TV, which provides a high-quality image and have low power consumption. We describe how we improved the optical design of the tandem light guide (TLG) and thus make a 10-mm thick BL. We also introduce how to correct device-to-device variations and temperature characteristics of RGBLEDs. Furthermore, we show how to estimate the optical properties of BLs in terms of the requirements for local dimming techniques. We found that a BL system Using TLGs has a higher contrast ratio between controllable and segmented blocks than conventional ones. This leads to our system being more suitable for local dimming techniques.
Our newly developed ultra-short throw distance laser light source projector is composed of triple rod illumination optics, mirror-lens hybrid ultra-wide angle projection optics and laser color processing. This projector has achieved the highest brightness of 7,000lm, the shortest throw distance of 60 cm at 100-inch image size and wider color gamut of 190% compared with sRGB by making full use of the advantages of laser such as high luminance, small etendue and high color purity. These specifications improve the visibility, convenience of installation and vividness of the image. In this paper, we describe our original developed technology such as the triple-rod illumination optical system, ultra-short projection optical system and laser color processing.
New display devices such as liquid-crystal displays, plasma displays, and organic LED displays, and high-definition (HD) TV formats may make a change in flicker visibility on displays. The flicker visibility for various viewing distances and light-emission duty ratios using a 44-inch diagonal flat light source was examined for this paper. As the viewing distance is reduced, the perceptible limit luminance of flicker decreases and the perceptible limit frequency increases. This implies that flicker is more perceptible for HDTV. The results show that a lower light-emission duty ratio, which is used to reduce the motion blur, requires a higher field frequency to prevent flicker. We proposed the empirical equations for the flicker-free field frequency and light-emission duty ratio as functions of the luminance. We found from these equations that more than 75 Hz of field frequency is required to prevent flicker when the duty ratio is 50% and the luminance is 300 cd/m2. In addition, more than an 81% duty ratio is required when the luminance is 300 cd/m2, the viewing distance is 3 H, and the field frequency is 60 Hz.
In recent years, many specific fields require accurate color reproduction for displays. Such fields are, for example, remote medical care, industrial design, electronic commerce, digital archives and color proofing of printed materials. Changes in chromaticity of the primary colors against the luminance level cause inaccurate color reproduction. This is a common problem in liquid crystal displays (LCDs). In this paper, we propose a method for correcting the phenomenon by using many colors conversion matrices made on the basis of the chromaticity shift of primary colors and luminance levels in the measured profile data of an LCD. Accurate color conversion was performed using the matrices, and the effectiveness of the conversion technique was confirmed. The application of the method enables reproduction of colors with accuracy three times as good as the Shaper Matrix Model. Moreover, it was achieved with a fewer matrices than that of the adaptive matrix color conversion.
We describe a prototype system for training the user in the art of ikebana, traditional Japanese flower arrangement. We have evaluated how well the user inserts a flower into a pinholder or ‘kenzan’. To obtain feedback on the force exerted onto the pinholder, we measured the force generated when the stem of a flower is inserted. We need to detect collisions that occur not only between the flowers and the pinholder but also among the flowers. Therefore, flower models have a hierarchical structure to perform the collision detection. According to the user's evaluations, they feel force when they are inserting a flower into a pinholder or when a flower they are holding contacts with another one already inserted in the pinholder.