Kuraray Co., Ltd.

Kuraray Plasmon Data Systems Co., Ltd.

Hideki Kobayashi

Koichi Saito

Minoru Ikeda

Shiro Nagata

Kazuo Funazaki

Koichi Horino

Yoichi Murayama

Yoshihiro Kumagai

Junji Nakagawa

Hajime Yamashita

Kiyoshi Morimoto

Rear projection type screen and method of manufacturing same

Provided is a Fresnel lens sheet having the advantage of reducing unnecessary rays of light that may go out around the center area of the concentrically-configured Fresnel lens of the sheet. When it is combined with a lenticular lens sheet to construct a viewing screen, the screen has the advantage of preventing white spots from appearing around its center area. The Fresnel lens sheet is for screens for rear projection image displays, and is characterized in that the lens pitch in the center area of the concentrically-configured Fresnel lens of the sheet differs from that in the peripheral area thereof, and that the lens pitch in the center area is larger than that in the peripheral area.

Fresnel lens sheet

Moire fringes are effectively solved in rear projection screens including a combination of a Fresnel lens sheet and a lenticular lens sheet both having fine lens pitches. In a rear projection screen including a Fresnel lens sheet having a lens pitch of at most 0.12 mm and a lenticular lens sheet having a lens pitch of at most 0.6 mm, the pitch, P,(mm), of the moire fringes that may be given by the Fresnel lenses and the lenticular lenses at a spatial frequency of at least 3/P,is at most 3 mm, the moire pitch, P,(mm), being given by formula (1), P,&equals;1/&verbar;n/P,&minus;m/P,&verbar; (wherein P,(mm) indicates the smaller one of the Fresnel lens pitch and the lenticular lens pitch, P,(mm) indicates the other one thereof, and n and m each are a natural number satisfying the formula (2), n&lE;15&times;P,/P,, and formula (3), m&lE;15&times;P,/P,).

Rear projection screen

A rear projection screen is used for a projection optical system where projected lights perpendicularly enter the screen from the rear face of the screen includes a Fresnel lens sheet incorporating a prism and a lenticular lens sheet that horizontally disperses lights emitted from the Fresnel lens sheet incorporating a prism. The Fresnel lens sheet incorporating a prism has a linear prism, which acts as a linear Fresnel lens for converging image lights in the screen height direction, at the projection light source side, and has a circular Fresnel lens, which acts to converge image lights in the direction of the screen center, at the observer side. According to the rear projection screen, the peak screen gain is increased and the peripheral luminance ratio is improved without degrading light utilization efficiency.

Rear projection screen incorporating a prism

A rear projection type image display device includes a single projection lens, a Fresnel lens sheet, and a lenticular lens sheet 4 having black stripes in an area where when the light entered through the Fresnel lens sheet is transmitted, the outgoing light does not pass. When the angle (deg) of incidence to the lenticular lens sheet 4 is taken to be .theta., the total light transmittance (%) of the lenticular lens sheet to the light with the angle .theta. of incidence is taken to be Tt(.theta.), and the light transmittance loss by a light absorbent contained in the lenticular lens sheet is taken to be .alpha., as shown by (b), (c) in FIG. 4, in the central part of the lenticular lens sheet, if .vertline..theta..vertline.=5, the expression Tt(.theta.)&gt;70.times.(1-.alpha.) is satisfied, and if .vertline..theta..vertline.=20, the expression Tt(.theta.)&lt;50.times.(1-.alpha.) is satisfied.

Rear projection type image display device

An optical recording medium comprising a plastic substrate having a surface of minutely roughened structure and a thin metal film formed on the substrate is capable of strongly absorbing laser light of a specific wavelength region, thereby writing data on the medium. The optical recording medium is characterized in that the thin metal film comprises a metal of the platinum group and a second metal or semi-metal such that the thermal conductivity of the thin metal film is not higher than 80% of the thermal conductivity of the platinum group pure metal. The optical recording medium is, since jitter has been decreased, capable of a high-sensitivity and high-CNR recording.

Optical recording medium and recording process utilizing the same

A process for producing an optical recording medium, comprising heat-treating an optical recording medium formed of a thin metal film on the minutely roughened surface of a plastic substrate, the medium being capable of strongly absorbing laser light of a specific wavelength region thereby being able to be written upon.

Production of optical recording medium

An optical recording medium which is made up of a plastic substrate having a surface of minute roughened structure and a metal thin film formed on the substrate and is capable of strongly absorbing laser light of a specific wavelength region, thereby writing data on the medium. The optical recording medium is characterized by an intermediate layer interposed between the plastic substrate and the metal thin film, the intermediate layer having a higher melting point or lower thermal conductivity than the metal thin film and having a thinner average thickness than the metal thin film. The optical recording medium has a definite recording threshold value and permits stable recording with a high CNR by using a broadly ranged recording power.

Optical recording medium

Metal tellurium is vaporized under the atmosphere of oxygen gas and/or inert gas formed into a plasma by a high frequency power to thereby form a tellurium oxide (TeOx, 0.ltoreq.X.ltoreq.2) layer. The tellurium oxide layer formed in accordance with the present method is stabilized, and a suboxide having a high sensitivity which has been considered to be unsuitable as an optical recording medium due to the lack of stability can be utilized. High frequency power, gas pressure and vaporization speed of metal tellurium can be varied to thereby vary the value X of TeOx from 0 to 2. When the TeOx films whose value X thicknesswise is different are formed continuously within one and the same vessel and the vaporization speed is made to zero, oxidization of a film surface may be carried out. Thereby, the TeO.sub.2 film may be formed on the surface, and an optical recording medium may be obtained which is extremely stable and has excellent adhesive properties between the substrates and between the layers.

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Niigata, Japan

Hideki Kobayashi