[in Japanese]

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Visual resolution limits of three types of color pixel arrangements for matrix display devices are discussed. Spatial Nyquist limits based on pixel inverse lattices are first introduced for all arrangements. Two subjective measurements are then carried out by evaluating still and moving sinusoidal patterns displayed on simulated screens, and two-dimensional visual resolution limit factors (corresponding to the Kell factor) are obtained quantitatively. For still patterns, the factors are about 0.6-0.7 for black & white patterns, and about 0.5-0.6 for single color patterns. A triangle arrangement is shown to be the best. For moving patterns, at an optimum velocity, the visual resolution limits usually improve at most about 10%-20% compared with those of still patterns. Relationships among the quality, velocity, and pixel arrangement are summarized.

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The reset mechanism in an amplified image sensor with a-Si : H photoconductive film is analyzed. The pixel elements in this device consist of three MOSFET's, used as an element-inherent amplifier, a Y-address switch and a reset switch for removing the integrated photocharges from the amplifier's gate.
Theoretical analysis and experimental results show that after the reset pulse is removed, the reset potential on the amplifier's gate is modified in four ways ; the device structure and operational conditions determine which way is dominant. The ligt-induced shift in the reset potential, which should resut in a large image lag, is found to be minimized by using an n-channel MOSFET as a reset switch and operating it in the linear region.
Additionally, a reset pulse with a fast fall time is shown to result in a large shift in the reset potential. This is usually accompanied by a larger reset noise.
To eliminate these problems, an optimal method for implementing the amplified image sensor is presented.

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“Telecine images” converted from film images have a lower frame rate than ordinary TV signals. This allows interlaced scan signals to be completely converted into progressive scan signals at IDTV receivers by using the “film-frame-closed” method. In this method, transmitted fields are combined into a TV frame every 2-or 3-field sequences (i.e., every film-frame sequence).
Hardware experiments of the above method, including subjective assessments, are descrived in this paper. The experiments clarify the following : (1) On average, the above method improves picture quality between 1 and 1.5 ranks on the CCIR seven-grade scale, compared with the conventional motion adaptive method. (2) Receivers can distinguish telecine images without the need for marker signals. (3) However, when other images, such as subtitles, are super-imposed, the method does not work well. Several solutions to solve this problem are also proposed.

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A digital audio signal transmission system that implements quadrature modulation for video carriers is examined for use in 2nd generation EDTV (Enhanced TV) systems.
Interference between audio and video signals, caused by the multiplex transmission of terrestrial broadcasting, is paid special attention to.
To improve the receiving quality of digital audio signals, reducing the crosstalk between video signals and the multiplexed signals is considered. Experiments show that using a two-dimensional waveform equalizer in conjunction with a line comb filter effectively reduces interference.
Reference signals used for quadrature multiplexing sent from broacasting stations are also studied. Results show that interference occurring in 8-field sequence GCR signal processing can be reduced by using a 4-field sequence sinX/X signal delayed by one-data period.

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[in Japanese]

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