Abstract: A backlight unit is provided including a light guide panel (LGP), a point light source emitting light at an edge of the LGP; and a refraction member being positioned between the point light source and the LGP and refracting the light emitted from the point light source toward the optical axis of the point light source in order to reduce the azimuth angle of the light that is incident upon the LGP. The refraction member includes a prism array in which a V-shaped prism pattern is repeatedly arrayed, the apex of the prism pattern facing the edge of the LGP, and a transparent portion that prevents the light from being totally reflected by the prism pattern in a region along an optical axis of the light source.

Abstract: A liquid crystal display device for displaying an image by changing orientation of a liquid crystal layer sealed between two substrates includes a lower substrate having a microstructure which outputs light incident on a side surface of the lower substrate to an upper surface of the lower substrate, a light source emitting light to the side surface of the lower substrate, a selective reflection panel provided on the upper surface of the lower substrate to reflect light having a predetermined incident angle or more and transmit the remaining light, and a reflection panel provided under the lower substrate.

Abstract: A backlight unit includes a light guide panel where a holographic pattern is formed. A point light source emits light to an edge of the light guide panel. A refractive member is provided between the point light source and the light guide panel and reduces an azimuth angle of light incident on the light guide panel. The refractive member includes, from an optical axis of the point light source, a light transmission zone transmitting light as it is, a blaze zone where a blaze pattern having a saw-toothed shape in which one surface near the optical axis and substantially parallel to the optical axis is formed, and a prism zone where a triangular prism pattern is formed. The backlight unit may further include a diffusive member diffusing light emitted from the point light source to be incident on the refractive member.

Abstract: A backlight unit includes a point light source emitting light and a light guide panel including a holographic pattern formed to have a concentric circle shape having a center at the point light center. Thus, since the incident azimuth angle of light incident on the holographic pattern can be made constant, an efficiency of light exhausted through the light exhaust surface can be improved. Also, since the distribution of the exhaust azimuth angle of the exhaust light can be made uniform, a uniform brightness can be obtained from the exhaust surface.

Abstract: An illumination apparatus for planar display devices, including an optical element for making light travel parallel to an optical axis, is provided. The illumination apparatus includes a dot light source for radiating light, and a light guide plate having the optical element. The optical element is composed of a first refraction facet, which is adjacent to the dot light source and increases the emission angle of the light, and a second refraction facet, which is isolated a predetermined distance from the first refraction facet while facing the first refraction facet and reduces the emission angle of the light. In this structure, the light travels parallel to the optical axis In the illumination apparatus, the emission angle of incident light is reduced, preferably, the light travels parallel to the optical axis.

Abstract: An optical scanning unit with a rotatable hologram disc, including a light source, a rotatable hologram disc provided with a plurality of holograms, the holograms being formed concentrically along a radial direction to diffract a beam emitted from the light source by multiple steps, a reflecting member that reflects the beam emitted from the light source and diffracted by one of the holograms into another hologram, and a fixed hologram correcting the diffracted beam incident through the rotatable hologram disc to focus it on a scanning object. In the optical scanning unit, the light passes through the plurality of holograms formed along a radial direction of the rotatable hologram disc so that a scan width can be extended without reducing a scan speed of the optical scanning unit.

Abstract: An appartatus for balancing a rotating member capable of preventing lubricity between balls from being reduced, and of enhancing balancing efficiency thereof. The rotational center of a turntable is the same as the center of the rotating member. A groove having a predetermined depth and a predetermined width is formed along the circumference of the turntable. A plurality of balls including first balls and second balls formed of different materials are alternately disposed in the groove. The first balls and the second balls may have different diameters.

Abstract: An optical scanning unit with a rotatable hologram disc, including a light source, a rotatable hologram disc provided with a plurality of holograms, the holograms being formed concentrically along a radial direction to diffract a beam emitted from the light source by multiple steps, a reflecting member that reflects the beam emitted from the light source and diffracted by one of the holograms into another hologram, and a fixed hologram correcting the diffracted beam incident through the rotatable hologram disc to focus it on a scanning object. In the optical scanning unit, the light passes through the plurality of holograms formed along a radial direction of the rotatable hologram disc so that a scan width can be extended without reducing a scan speed of the optical scanning unit.

Abstract: A beam scanning system including: a light source; a deflection disc rotatably installed over the light sources and having a hologram pattern on each of the upper and lower surfaces thereof, for diffracting beams emitted from the light source; and a plurality of mirrors for reflecting beams that have been diffracted by the deflection disc, to change the diffracted paths of the beams. Each of the upper and lower hologram patterns is formed with a low density relative to a one-sided hologram pattern.

Abstract: A diffractive deflection beam scanning system including: a plurality of light sources; a deflection disc rotatably mounted over the light sources, having patterns capable of diffracting and deflecting beams emitted from the light sources; a plurality of first reflecting mirrors for changing the traveling paths of beams diffracted and deflected by the deflection disc; a plurality of second reflecting mirrors for reflecting the beams reflected by the first reflecting mirrors in a beam scan direction, wherein the light sources are disposed in a straight line along a bisecting line of the deflection disc, perpendicular to the beam scan direction, and the second reflecting mirrors are arranged over the center of the deflection disc at different heights.

Abstract: A multi-laser scanning unit (LSU) in which scanning lines incident parallel onto a photoreceptor have the same scanning direction. The multi-laser scanning unit includes: a driving source for providing a rotatory force; a deflection disk installed around a rotary shaft of the driving source having a plurality of sectors each with a hologram pattern for diffracting and deflecting incident light, for scanning light through rotation; a plurality of light sources installed facing one surface of the deflection disk for irradiating a plurality of light lines onto predetermined points of the deflection disk; and a light path changing portion for changing traveling paths of the plurality of scanning lines formed by the rotation of the deflection disk, wherein the plurality of light sources are arranged such that two incident points which are the farthest from each other among the plurality of incident points formed on the deflection disk form 180° with the center point of the deflection disk.

Abstract: A hemispherical dynamic pressure bearing comprises a bushing in which a hemisphere/shaft unit is mounted with clearance, enabling the unit to move relative to the bushing between first and second terminal positions. In order to measure the size of the clearance, the bearing is inserted into a body, and a retainer disposed in the body is actuated for keeping the bushing stationary. An adjusting mechanism disposed in the body is actuated for displacing the hemisphere/shaft unit vertically relative to the bushing between the first and second terminal positions, wherein the hemisphere/shaft unit projects from an end of the bushing by first and second heights, respectively. Those heights are measured and a difference therebetween is determined, which difference corresponds to the clearance.

Abstract: A hemispheric bearing apparatus for preventing deformation of a hemisphere occurring when a shaft is push-fitted into a shaft inserting hole formed at the center of a hemisphere in a hemispheric bearing which supports a thrust load and a radial load at the same time, the apparatus including a pair of hemispheres fitted into a fixing shaft to face each other around a spacer, and having a first section disposed opposite to the spacer and a second section contacted with the spacer; a first deformation preventing portion formed in the first section at a predetermined distance around the fixing shaft to prevent deformation of the hemispheres; and a second deformation preventing mechanism formed in the second section at a predetermined distance around the fixing shaft to prevent deformation of the hemispheres.

Abstract: A hemispheric bearing apparatus which enables a bushing to rotate without contacting a hemisphere. The hemispheric bearing apparatus according to the present invention includes hemispheres, the bushing which has hemispheric grooves formed at both ends, for receiving the hemispheres, and a spring for forcing the hemisphere or the bushing to each other in order for the hemisphere to be closely positioned with the bushing.

Abstract: A head drum of a tape recorder has a weight balancing device for preventing vibrations occurring during the revolution of the head drum. In particular, the head drum includes a stationary drum fixed to a deck, a rotary drum rotatably installed above the stationary drum, and a circular weight balancing plate installed coaxially with the rotary drum and having a plurality of removable portions formed therein which can be removed by an external force.

Abstract: A hemispherical dynamic pressure bearing includes a supporting shaft, a fixed hemisphere fixed on a first end of the supporting shaft, and a sliding hemisphere slidably disposed on a second end of the supporting shaft. A spring is disposed on the supporting shaft for biasing the sliding hemisphere away from the fixed hemisphere. A bushing has first and second hemispherical grooves in which the fixed and sliding hemispheres are disposed, respectively. A gap adjuster is connected to the shaft for adjusting a gap between each hemisphere and its respective groove. The gap adjuster applies a variable force against the sliding hemisphere to compress the spring.

Abstract: A magnetic recording/reproducing apparatus comprises windbreak members between a rotary head drum and a guide mechanism so as to prevent airflow between the head drum and the tape. Such a magnetic recording/reproducing apparatus significantly reduces the rising of the magnetic tape from the outer circumferential surface of the rotary head drum, to enable the tape's close contact with the head drum. Also, tape oscillation and subsequent signal jitter is reduced to enhance high-density and highly accurate magnetic recording and reproduction.

Abstract: A device for forming a spiral groove on the inner walls of a cylindrical cavity including a rod having a cylindrical recess and pair of through holes, machining balls in the through holes, a tapered support located in the cylindrical recess, whose tapered sides support the machining balls, a spring located between the support and the other end of the cylindrical recess for supporting the support, and a push cap coupled to the aperture of the recess for deciding the location of the support by pressing the support supported by the spring. The device can freely adjust the height of the machining balls protruding from in the through holes according to the inner diameter of a bearing's cylindrical cavity, thereby easily forming spiral grooves of uniform depth.