Abstract: A Fresnel lens sheet holding structure holds a thin Fresnel lens sheet formed on a forming mold easily releasable from the forming mold in a satisfactory planarity on a rear projection display. A rear projection display is provided with the Fresnel lens sheet holding structure. The Fresnel lens sheet holding structure holds a Fresnel lens sheet of 3 mm or below in thickness having an entrance surface provided with prisms of a triangular cross section each having an entrance facet and a total-reflection facet that reflects part or all of light fallen on the entrance facet in a total-reflection mode to deflect the light in a desired direction. The Fresnel lens sheet holding structure includes a hanging member to be attached to the upper side of the Fresnel lens sheet, and a support member for supporting the hanging member. Preferably, a tensioning member is attached to the Fresnel lens sheet.

Abstract: The present invention provides a Fresnel lens sheet that can, in production using a mold, be easily released from the mold and that scarcely produces stray light upon use, and others. Each prism 2 on the incident side of a Fresnel lens sheet 1 is formed to have a nearly triangular cross section and has a plane of refraction 3 that refracts projected light S incident on this plane and a plane of total reflection 4 that totally reflects, toward the viewer's side, at least part of the light refracted at the plane of refraction 3. Each prism 2 is made so that a root 5 between a prism 2 and a prism 3 situated next to the prism 2, on the plane of total reflection side of the prism 2 (a root 5 defined by the plane of refraction 3 of one prism 2B and the plane of total reflection 4 of another prism 2A situated next to the prism 2B, on the side of the plane of refraction 3 of the prism 2B) is curved toward the prism 2A side from the prism 2B side.

Abstract: There is provided a Fresnel lens sheet for converging light rays fallen thereon from oblique directions, and capable of reducing the reflection of external light, of enabling displaying images in satisfactory contrast, of suppressing the occurrence of moiré and of being easily manufactured. The Fresnel lens sheet 10 includes: a flat base part 11; a plurality of prisms 12 formed on the entrance surface of the base part 11, a plurality of V grooves 13 formed in the exit surface of the base part 11, and a plurality of wedge-shaped light absorbing parts 14 embedded in the V grooves 13, respectively. Each prism 12 has a refraction facet 12a that refracts light rays fallen thereon and a total-reflection facet 12b that totally reflects light rays fallen thereon. The prisms 12 refract and reflect light rays L1 incident thereon at large incident angles to deflect the light rays L1 for travel in a direction substantially perpendicular to the base part 11.

Abstract: A Fresnel lens sheet comprises a Fresnel lens on one surface thereof, wherein respective unit surfaces constructing the Fresnel lens sheet have rough surfaces. Since it has a rough surface, it enables suppressing the occurrence of moire, when making up a screen. The other Fresnel lens sheet comprises a Fresnel lens on one surface thereof, and a fly-eye lens or prisms as a regular concavities and convexities configuration for suppressing regular reflection on the surface thereof on a side opposite to the side having the Fresnel lens formed thereon. Since it has on its rear surface a fly-eye lens or a prism, it enables suppressing the occurrence of ghost image.

Abstract: A Fresnel lens sheet has an entrance surface (1a) and an exit surface (1b). A plurality of prisms (2) each having a refraction surface (3) and a total-reflection surface (4) are formed on the entrance surface (1a). Light rays projected by a light source (M) disposed on the side of the sloping refraction surfaces (3) onto the entrance surface (1a) are refracted at the refraction surfaces (3), and the refracted light rays are totally reflected by a total-reflection surfaces (4) in a direction substantially perpendicular to a sheet surface (1c). Angles (?) between the refraction surfaces (3) and the total-reflection surfaces (4) corresponding to the refraction surfaces (3) of all the prisms (2) are substantially equal to each other. The angle ? between the refraction surface (3) of the prism (P2) farthest from the light source (M) and the sheet surface (1c) is approximately equal to a right angle.

Abstract: A Fresnel lens sheet comprises a Fresnel lens on one surface thereof, wherein respective unit surfaces constructing the Fresnel lens sheet have rough surfaces. Since it has a rough surface, it enables suppressing the occurrence of moire, when making up a screen. The other Fresnel lens sheet comprises a Fresnel lens on one surface thereof, and a fly-eye lens or prisms as a regular concavities and convexities configuration for suppressing regular reflection on the surface thereof on a side opposite to the side having the Fresnel lens formed thereon. Since it has on its rear surface a fly-eye lens or a prism, it enables suppressing the occurrence of ghost image.

Abstract: The present invention provides a Fresnel lens sheet capable of effectively preventing such troubles as the production of double images that occurs due to stray light. A Fresnel lens sheet (1) comprises a base (1a) in sheet form, and a plurality of prisms (2) formed on the incident side of the base (1a). Each prism (2) has a plane of refraction (3) that refracts imaging light (LS) projected from a projector (5), and a plane of total reflection (4) that totally reflects, toward the viewer's side, at least a part of the light that has been refracted at this plane of refraction (3). At least some of a plurality of the prisms (2) are so made that the imaging light (LS) that has passed through these prisms (2) emerges in the direction inclined toward the projector (5) side at predetermined angles (?b, ?c) with respect to the normal perpendicular to the sheet plane of the base (1a).

Abstract: A projection screen 111 comprises a total reflection prism lens 114 and a lenticular lens 115 provided on the viewer's side of the total reflection prism lens 114. The total reflection prism lens 114 has a plurality of unit prisms 113 on its back surface (the outermost plane of incidence) on which imaging light L is incident. Each unit prism 113 has an apical angle ? that corresponds to the angle between the plane of incidence 113a and the plane of total reflection 113b, and the apical angles ? of the unit prisms 113 vary with the position of each unit prism 113 on the screen plane. In particular, the unit prisms 113 have apical angles ? varying continuously from 30° to 45° so that the apical angles ? on the side distant from the center O of the concentric circles are greater than the apical angles ? on the side close to this center O.

Abstract: A rear projection screen 3 includes a single Fresnel lens sheet 11 having the function of converging projected light entering from its back side and allowing the converged light to emerge from its observation side, or a combination of the Fresnel lens sheet 11 provided on the back side and a lenticular lens sheet 21 provided on the observation side. The Fresnel lens sheet 11 has a Fresnel lens 12 on its observation-side surface and a matte surface 13 as its back-side surface. The matte surface 13 of the Fresnel lens sheet 11 has a specified degree of matting and shows antireflection properties. Preferably, the Fresnel lens sheet 11 has a haze value in a specified range. More preferably, the matte surface 13 of the Fresnel lens sheet 11 has a gloss in a specified range.

Abstract: A Fresnel lens has a plurality of pitch areas in which a plurality of hybrid type prism portions are arranged. Each hybrid type prism portion has a refraction type prism portion and a total reflection type prism portion. In the refraction type prism portion, a ray of incident light Li1 of an incident angle “a” is refracted twice and goes out as a ray of outgoing light Lo1 of an outgoing angle “f”. In the total reflection type prism portion, a ray of incident light Li2 of the incident angle “a” is refracted, totally reflected and refracted in that order and goes out as a ray of outgoing light Lo2 parallel to the ray of outgoing light Lo1.

Abstract: A Fresnel lens sheet has an entrance surface provided with a plurality of total-reflection Fresnel lens elements. Each of the total-reflection Fresnel lens elements has a light-receiving facet and a total-reflection facet that deflects part of or all the image light fallen on the light-receiving facet in a desired direction. The Fresnel lens sheet meets a requisite condition expressed by an expression: A1≦0.6T1/L1, where L1 (mm) is the horizontal length of the Fresnel lens sheet, T1 (mm) is the thickness of the Fresnel lens sheet, and A1 (%) is maximum elongation percentage of the Fresnel lens sheet at which the Fresnel lens sheet lengthens due to moisture absorption. The Fresnel lens sheet includes a Fresnel lens element sheet, and an auxiliary sheet attached to the exit side of the Fresnel lens element sheet. The Fresnel lens element sheet enables efficient molding-removing work for removing the Fresnel lens element sheet from a mold.

Abstract: The present invention provides a Fresnel lens sheet that can, in production using a mold, be easily released from the mold and that scarcely produces stray light upon use, and others. Each prism 2 on the incident side of a Fresnel lens sheet 1 is formed to have a nearly triangular cross section and has a plane of refraction 3 that refracts projected light S incident on this plane and a plane of total reflection 4 that totally reflects, toward the viewer's side, at least part of the light refracted at the plane of refraction 3. Each prism 2 is made so that a root 5 between a prism 2 and a prism 3 situated next to the prism 2, on the plane of total reflection side of the prism 2 (a root 5 defined by the plane of refraction 3 of one prism 2B and the plane of total reflection 4 of another prism 2A situated next to the prism 2B, on the side of the plane of refraction 3 of the prism 2B) is curved toward the prism 2A side from the prism 2B side.

Abstract: A Fresnel lens has a plurality of pitch areas in which a plurality of hybrid type prism portions are arranged. Each hybrid type prism portion has a refraction type prism portion and a total reflection type prism portion. In the refraction type prism portion, a ray of incident light Li1 of an incident angle “an” is refracted twice and goes out as a ray of outgoing light Lo1 of an outgoing angle “f”. In the total reflection type prism portion, a ray of incident light Li2 of the incident angle “a” is refracted, totally reflected and refracted in that order and goes out as a ray of outgoing light Lo2 parallel to the ray of outgoing light Lo1.

Abstract: The present invention relates to encoding and decoding of digital audio data enabling change of reproducing speed without degradation of articulation of audio while being compatible with various digital contents. In the encoding, a pair of a sine component and a cosine component digitized are generated at each of preset discrete frequencies and, by use of these sine component and cosine component, each of amplitude information items of the sine component and the cosine component is extracted from digital audio data sampled at a predetermined sampling period. Then frame data consisting of pairs of amplitude information items of sine and cosine components extracted corresponding to the respective discrete frequencies is successively generated as part of encoded audio data.

Abstract: A Fresnel lens sheet of the present invention is applicable to a transmission-type projection screen, which comprises a layered structure provided with at least a base material layer, a lens layer formed into a Fresnel lens configuration, an incident surface on which projection light is incident and an light-emission surface from which the projection light is emitted, wherein a total reflection surface is disposed in the layered structure at a position between the incident surface and the light-emission surface, the total reflection surface totally reflecting a portion of projection light proceeding on an optical path in a direction from the lens layer side toward the base material layer side.

Abstract: A laser apparatus comprises a beam distributor to distribute a pumping beam over a laser medium. The beam distributor comprises a beam conductor having an incident surface and an intermediate surface smaller than the incident surface. The beam conductor conducts the pumping beam received by the incident surface to the intermediate surface. A main body is connected to the intermediate surface and has a plurality of surfaces and confines the pumping beam introduced through the intermediate surface by repeating total internal reflection at the surfaces. When the intermediate surface becomes small, quantity of the pumping beam escaping from the intermediate surface becomes small. The main body distributes the pumping beam confined therein over the laser medium where the laser medium is in contact with the surfaces of the main body.

Abstract: In a longitudinal flexible composite optical medium (3) for use in a laser device, the longitudinal flexible composite optical medium includes a laser beam guide portion (1) containing a laser active material (11) and an excitation beam guide portion (2) for distributing and introducing an excitation beam into the laser beam guide portion. The laser beam guide portion and the excitation beam guide portion are uncoaxially arranged in parallel to each other and integrally coupled with each other. By winding or folding the composite optical medium, a laser structure of a predetermined shape is obtained.

Abstract: A rear projection screen 3 includes a single Fresnel lens sheet 11 having the function of converging projected light entering from its back side and allowing the converged light to emerge from its observation side, or a combination of the Fresnel lens sheet 11 provided on the back side and a lenticular lens sheet 21 provided on the observation side. The Fresnel lens sheet 11 has a Fresnel lens 12 on its observation-side surface and a matte surface 13 as its back-side surface. The matte surface 13 of the Fresnel lens sheet 11 has a specified degree of matting and shows antireflection properties. Preferably, the Fresnel lens sheet 11 has a haze value in a specified range. More preferably, the matte surface 13 of the Fresnel lens sheet 11 has a gloss in a specified range.

Abstract: A Fresnel lens has a pitch including a hybrid prism comprising a refraction prism unit (3A) for emitting an incident light (li1) of an incident angle (a) as an outgoing light (lo1) of an outgoing angle (f) by two refractions, and a total reflection prism unit (4A) for emitting an incident light (li2) of an incident angle (a) as an outgoing light (lo2) parallel to the outgoing light (lo1) by a refraction, a total reflection, and a refraction.

Abstract: A Fresnel lens sheet comprises a Fresnel lens on one surface thereof, wherein respective unit surfaces constructing the Fresnel lens sheet have rough surfaces. Since it has a rough surface, it enables suppressing the occurrence of moire, when making up a screen. The other Fresnel lens sheet comprises a Fresnel lens on one surface thereof, and a fly-eye lens or prisms as a regular concavities and convexities configuration for suppressing regular reflection on the surface thereof on a side opposite to the side having the Fresnel lens formed thereon. Since it has on its rear surface a fly-eye lens or a prism, it enables suppressing the occurrence of ghost image.