Fujifilm Corporation

Fuji Photo Film Company, Limited

Fujfilm Corporation

Osamu Iwasaki

Toshiaki Endo

Hiroshi Hara

Ryuichi Katsumoto

Takamitsu Okumura

Koji Yoshida

Hiroo Inaba

Kazuo Hakamata

Seiichi Watanabe

Hiroshi Sunagawa

Satoru Hayakawa

Atsushi Uejima

Akihiko Takeda

Takeshi Nagata

Makoto Koike

Takaaki Aihara

A large-sized thin light guide plate has a first layer on a light exit surface side and a second layer on a rear surface side containing scattering particles at a higher particle concentration than the first layer. Thicknesses of the layers in a direction substantially perpendicular to the light exit surface change to change a combined particle concentration. The scattering particles, obtained by mixing a particle group with an average particle size Ds of less than 7 &#x3bc;m having one or more local maximum values and a particle group with an average particle size Db of more than 7 &#x3bc;m having one or more local maximum values, satisfy 1 &#x3bc;m&#x2266;Ds&#x3c;7 &#x3bc;m, 7 &#x3bc;m&#x3c;Db&#x2266;12 &#x3bc;m and 0.3&#x2266;a&#x2266;0.5. High light use efficiency, reduction of luminance and color unevenness, a convex brightness distribution and easy manufacture can be achieved.

Light guide plate

There is provided a planar lighting device which can emit light with high light use efficiency and small luminance unevenness. This object is achieved by having a light guide plate including two or more layers overlapping in a direction perpendicular to a light exit surface and having different particle concentrations of the scattering particles, thicknesses of the layers in the direction perpendicular to the light exit surface varying so that a combined particle concentration has, in a direction perpendicular to a light incidence surface, a first local maximum value closer to the light incidence surface and a second local maximum value located farther from the light incidence surface than the first local maximum value and being larger than the first local maximum value; and a micro-lens film having a plurality of spherical micro-ball lenses formed on a film.

Planar lighting device

The light guide plate has a first light incidence surface and a second light incidence surface which are provided on end sides of a light exit surface and are orthogonal to each other. The light guide plate includes two or more layers superposed on each other in a direction substantially perpendicular to the light exit surface and containing scattering particles at different particle concentrations. The thicknesses of the two or more layers in the direction substantially perpendicular to the light exit surface change so that a combined particle concentration of the light guide plate has, in directions perpendicular to the light incidence surfaces, a first local maximum value located on sides closer to the light incidence surfaces and a second local maximum value located at positions farther from the light incidence surfaces than positions of the first local maximum value and being larger than the first local maximum value.

Light guide plate and planar lighting device

The light guide plate has at least two layers which are superposed on each other in the direction almost perpendicular to the light exit surface and contain the scattering particles at different particle concentrations, the scattering particles are polydisperse particles including a mixture of particles with different particle sizes, and the combined particle concentrations in each portion of the light guide plate is different by changing the thicknesses of the first layer and the second layer in the direction almost perpendicular to the exit surface.

Light guide plate, planar lighting device, and liquid crystal display device

The light guide plate includes two or more layers superposed on each other in a direction substantially perpendicular to a light exit surface and containing scattering particles at different particle concentrations. The thicknesses of the two or more layers in the direction substantially perpendicular to the light exit surface are changed so that the combined particle concentration of the light guide plate has, in a direction perpendicular to at least one light incidence surface, a first local maximum value on at least one side closer to the at least one light incidence surface and a second local maximum value located at a position farther from the at least one light incidence surface than at least one position of the first local maximum value and being larger than the first local maximum value.

A light guide plate comprises: a rectangular light exit plane and at least one light entrance plane in contact with the light exit plane, wherein the light guide plate comprises three or more structural layers disposed on each other in a direction normal to the light exit plane, each structural layer containing scattering particles dispersed therein, the structural layers having different particle densities of scattering particles.

A planar lighting device includes: a light source that emits light; and a light guide plate disposed opposite the light source in which light emitted from the light source enters and is emitted therefrom as planar light. The light guide plate includes a flat light exit plane that emits the planar light, a light entrance plane that is formed opposite the light source and includes one side of the light exit plane, an end plane that includes the opposite side to the one side of the light exit plane, and a rear plane formed on the side opposite the light exit plane. The rear plane includes a first rear plane that is joined with the end plane and is smoothly inclined to said light exit plane so that the distance from the light exit plane increases as the distance from the end plane increases, and a second rear plane.

A planar lighting device comprises: a light guide plate including a concave rectangular light exit plane, two light entrance planes containing two opposite sides of the light exit plane and disposed opposite each other, two symmetrical inclined planes opposing to the light exit plane such that their distance from the light exit plane increases with the increasing distance from the two light entrance planes toward the center of the light exit plane, a curved portion connecting the two inclined planes; two light sources respectively disposed opposite the two light entrance planes for emitting light to enter the light into the light guide plate through the light entrance planes; and sliding mechanisms allowing the light sources to slide in a direction parallel to the light entrance planes of the light guide plate to absorb the expansion and contraction of the light sources along the length thereof.

The transparent light guide plate includes a rectangular light exit surface, a thick portion positioned at substantially a central portion of the surface, thin edge portions formed in parallel on both sides of the thick portion, a parallel groove accommodating a bar-like light source and being formed at substantially a center of the thick portion and inclined rear portions whose thickness is reduced from the thick portion toward the thin edge portions. An end portion of the groove is narrowed toward the surface symmetrically to a center line of the groove in a sectional shape thereof according to a ratio of a peak value of illuminance or luminance of emitted light at a first portion of the surface corresponding to the groove to an average value thereof at second portions corresponding to the inclined rear portions. The planar lighting device includes the light guide plate. The liquid crystal display device includes the planar lighting device.

Light guide plate, and planar lighting device and liquid crystal display device using the same

The planar lighting device includes a light guide plate having the light exit plane, two pairs of light entrance planes formed at the four sides of the light exit plane, and rear planes formed opposite to the light exit plane and inclined such that the light guide plate grows thicker toward the center thereof, a pair of main light sources and a pair of auxiliary light sources disposed opposite their respective light entrance planes to emit light to the respective light entrance planes, and illuminance distribution control unit to adjust the amount of light emitted by the main and auxiliary light sources to form a designated local illuminance distribution for any position desired in the light exit plane. The planar lighting device performs area control and line control to adjust illuminance at a light exit plane for any area desired and along any line desired, respectively.

It is an object to provide a planar illumination device that is thin and light weight, and can emit uniform illumination light with little brightness unevenness and can be enlarged in size. It is to provide a planar illumination device comprising: a first light source and a second light source which are arranged at predetermined intervals; and a light guide plate which is arranged between the first light source and the second light source and has: a light exit surface; a first light incident surface which is opposed to the first light source and includes a side of the light exit surface; a second light incident surface which is opposed to the second light source and includes an opposite side to the side; and a rear surface which is formed to be opposed to the light exit surface, wherein a cross section on a plane perpendicular to the side, of the rear surface of the light guide plate has a curved line in which a distance from the light exit surface increases with a shift from the first light incident surface and the second light incident surface to a center, an inclined angle relative to the light exit surface reduces with a shift from the first light incident surface or the second light incident surface to the center, and the inclined angle relative to the light exit surface is zero degrees at the center.

Planar illumination device

The planar lighting device includes, in addition to light sources, a light exit plane, a pair of light entrance planes formed on a pair of sides of the light exit plane, and a rear plane composed of a pair of inclined planes formed on a side opposite from the light exit plane such that the light guide plate grows thicker with an increasing distance from the light entrance planes toward the center. The light guide plate contains light scattering particles satisfying Npi&#x3e;Np, where Npi is the particle density in a region of space within a given range of the light guide plate and Np the density in the other region of space. The planar lighting device with minimized brightness unevenness liable to develop near the light entrance planes when the light exit plane has great dimensions.

A wedge shaped lighting device includes a light source and a light guide plate disposed opposite to the light source, and the light guide plate includes a light entrance plane opposite to the light source and a light exit plane containing one side of the light entrance plane, and has a shape growing thicker in direction perpendicular to the light exit plane with the increasing distance from the light entrance plane and contains scattering particles for scattering light entering through the light entrance plane and propagating the inside thereof.

Wedge-shaped lighting device

In order to provide a larger-sized light guide plate that is thin and lightweight and allows more uniform, less uneven and higher-luminance illuminating light to emit from a light exit surface, a sectional shape of each back surface of the rectangular light exit surface satisfies the following 10th-order function formula. X is a position from the origin in a direction parallel to the one side of the light guide plate, and Y is a position from the origin in a direction perpendicular to the one side. Y=A+A&#xd7;X+A&#xd7;X+A&#xd7;X+A&#xd7;X+A&#xd7;X+A&#xd7;X+A&#xd7;X+A&#xd7;X+A&#xd7;X+A&#xd7;X, &#x2212;1.3&#xd7;10&#x2266;A&#x2266;2.4&#xd7;10, &#x2212;2.0&#xd7;10&#x2266;A&#x2266;9.4&#xd7;10, &#x2212;2.6&#xd7;10&#x2266;A&#x2266;5.7&#xd7;10, &#x2212;5.5&#xd7;10&#x2266;A&#x2266;2.2&#xd7;10, &#x2212;2.1&#xd7;10&#x2266;A&#x2266;1.1&#xd7;10, &#x2212;3.7&#xd7;10&#x2266;A&#x2266;2.2&#xd7;10, &#x2212;1.4&#xd7;10&#x2266;A&#x2266;3.3&#xd7;10, &#x2212;3.6&#x2266;A&#x2266;1.5, &#x2212;7.8&#xd7;10&#x2266;A&#x2266;3.3&#xd7;10, &#x2212;1.2&#xd7;10&#x2266;A&#x2266;3.2&#xd7;10, &#x2212;1.4&#xd7;10&#x2266;A&#x2266;4.9&#xd7;10. A planar lighting device includes the light guide plate, and a liquid crystal display apparatus includes the planar lighting device as a backlight unit.

Light guide plate, as well as a planar lighting device and liquid crystal display apparatus using the same

Provided is a planar lighting device having a thin shape and capable of emitting uniform illumination light with less brightness unevenness. The planar lighting device includes a first and a second light sources arranged at a given distance apart from each other and a light guide plate arranged between the first and second light sources. The light guide plate includes a light exit plane, a first light entrance plane facing the first light source and containing one side of the light exit plane, and a second light entrance plane facing the second light source and containing the opposite side to the one side, and has a shape growing thicker from the first and second light entrance planes toward the center. The light guide plate contains scattering particles for scattering light entering through the first and second light entrance planes and propagating inside by a ratio satisfying 1.1&#x2266;&#x3a6;&#xb7;N&#xb7;L&#xb7;K&#x2266;8.2.

Growing community of inventors

Kanagawa, Japan

Osamu Iwasaki