Reiichi Sasaki

Observation of Thermally Generated Carrier in Charge Coupled Devices

The build-up of thermally-generated carriers in a charge coupled device (CCD) is investigated by considering a generation model proposed by Zerbst that characterizes the transient response of an MOS capacitor. By applying clock pulses in a holding mode to a pair of electrodes of a 4-phase, 128-bit CCD shift register, noise signals of the generated carriers were observed when the duration of the holding mode reached several msec. By comparing experimental results with the theoretical transient response derived from the Zerbst model, the minority carrier lifetime τ and the surface generation velocity SG are determined to be in reasonable agreement with the values evaluated from transient responses of the MOS capacitor.

Sophisticated Vir-Signal Processing in a Home VCR and Associated Developments

The VIR-Signal, which corrects distortions suffered during transmission, is being utilized in color television receivers from various manufacturers1). These receivers suffer from the unacceptable control of tint and saturation when the VIR-Signal is supplied through a home VCR of azimuth recording type such as VHS2) or Beta.

Non-Linear Chrominance Signal Decoding

The NTSC color system specifications are based on three color primaries with given chromaticity coordinates and a specified reference white. Although the signal specifications are unchanged, the receiver color primaries have changed from the NTSC color primaries because of adesire for increased display brightness. These modern primaries increase the transmission errors and noise, and also force some sacrifice in colorimetric fidelity.

A Design Method of Front-end Circuits in CATV Receivers

CATVの普及により多数チャンネルを受信する場合, チャンネル間の妨害が最も問題となる.混合器を含む受信回路では, 混合素子の伝達特性の2次の非直線成分により, 他チャンネルの受信チャンネルへの妨害が本質的に発生する.筆者らは, 混合素子の妨害信号特性を評価するとともに, この妨害を避ける周波数関係を解析し, 最適な周波数変換方式を求めることにより, 多数チャンネル受信に適した回路設計法を提案した.

A Simplified Cross-Color Suppression Circuit for Color Television Receivers

In a color television system the frequency components of the luminance and the chrominance signals consist of line spectra, the component frequencies of which are separated by harmonics of the line frequency. By being interleaved betwee. n the luminance frequencies, the chrominance frequencies share the passband near its high frequency end. The detected luminance signal in a receiver contains the color subcarrier, which produces an image with crawling dots and edges.

Improvement of Color Reproduction of Color Television Receivers

NTSC原色点と異なる色度の螢光体を使用した最近の受像機において, 再現色の色度誤差, 輝度誤差, ノイズ妨害の問題を含めた補正法について検討し, 色信号伝送系に必要な非線形特性を明らかにするとともに, 実用的な補正方式を開発した.本方式による改善度は, 再現色の平均輝度誤差が5分の1に, 最大輝度誤差が10分の1に軽減され, ノイズ妨害量では最大8dBの改善が得られる.

Modulation Transfer Function and the Subjective Image Sharpness of Color Picture Tubes

受像管のレスポンス特性を定量的に評価するために, レスポンス特性と画像の主観的鮮鋭度の関係を調べる実験を行い, 合理的な評価法を求めた.これにより代表的なカラー受像管を判定し, ブルーミング, 画面周辺部での鮮鋭度劣化が重要な問題であることを指摘した.また, 従来重要視されなかった偽解像現象について探究し, ブルーミングは偽解像現象を生じることもあること, 偽解像の原因は主に球面収差であることを明らかにするとともに, 補正磁界の影響, UPF管の特長にも触れ参考に供した.