Yoshitomi Nagaoka

Lens and Optics for Optical Disk System

Various types of pick-up lenses and optical systems for pick-ups are discussed. We evaluated optical performances of objective lenses. Aspherical lenses for CD player pick-ups have wider field angle compared to the conventional triplet objective lens. We also evaluated reliability of both plastic and glass molded lenses which are designed in the same way. Plastic lens caused spherical aberration due to temperature change. Optical pick-ups for CD players are remarkably simplified by means of aspherical lens or holographic element. On the other hand, pick-ups for write once or erasable optical disk system consist of many optical components. For these pick-ups, we developed a single bi-aspheric molded glass lens which has high NA (0.55) and remarkable light weight (85mg).

Single Lens CD Player Pickup System Using a Bi-Aspheric Molded Glass Lens

Since compact disc (CD) players were first introduced in 1982, they have been prevailing at a remarkable speed. The number of shipped CD players is assumedly eight to nine millions in 1986. Following this first generation CD player of fixed installation type, portable or radio cassette CD players and CD players for car use are supposed to prevail as a second generation. For these CD players, mass production, lower cost and performance reliability in hot and humid environment are demanded.

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.

Super Compact Plastic Projection Lensen for Projection Televisions

A new compact plastic lens is proposed to meet demands for further reduction of a projection TV cabinet size while maintaining high image quality with a newly developed stop for cutting off undesirable sagittal aberration.

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 two-channel recording VCR using orthogonal arrangement of heads

The authors describe a novel design technique for FM carrier allocation and an improved two-channel recording technique allowing both standard and long-play modes. Consequently, the experimental VCR can be used as a wide-screen-TV recorder. Experimental results confirm that this high-efficiency recording technique provides a picture quality nearly equal to that of the VCR for broadcast use with 1/2-inch conventional video tape. For users of conventional TV a converter from wide-screen to conventional signal format has been developed. >

New Compact Optical Systems For Projection Televisions

We have developed a new optical system which enables the miniaturization of the lens sys tem for projection. televisions, while maintaining a high. resolution image. This optical system consists of a simple 3-lens element and a new radially arranged baffle stop. Using this optical system, lens length can be reduced by 25% concomitantly resulting in smaller projection TV. cabinets.

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.