Sharp Kabushiki Kaisha Corporation

Takahiro Miyake

Yukio Kurata

Yoshio Yoshida

Yasuo Nakata

Keiji Sakai

Tetsuo Ueyama

Kazuhiko Ueda

Nobuo Ogata

Hideaki Sato

Katsuhiro Kubo

Makoto Horiyama

Kenji Ohta

Hiroyuki Katayama

Junichiro Nakayama

Toshiyuki Tanaka

Tomoyuki Miyake

Hiroyuki Yamamoto

Kohji Minami

Toshio Ishikawa

Osamu Miyazaki

Renzaburo Miki

Noboru Fujita

Shozo Kobayashi

Yukinori Nishitani

Chiaki Kiyooka

Hiroshige Makioka

Katushiro Kubo

Yukio Kubata

An optical pickup () projects a read beam onto an optical disc () as an optical storage medium which is driven to rotate by a spindle motor () and receives its reflection. A laser beam from a laser producing element () passes through a liquid crystal panel () and guided to an objective lens (). The panel () is provided to correct spherical aberration caused by an irregular thickness of a transparent substrate of the optical disc (). A control circuit () changes a spherical aberration correction signal SA to carry out sampling more than once, covering a range of the output of an optical sensor () where the output shows large changes. The circuit () determines the position of a peak of an approximation curve through calculation and designates that position as the magnitude of correction. Thus, the optical pickup () can quickly and accurately detect the magnitude of the correction of the spherical aberration caused by an irregular thickness of the optical disc ().

Optical pickup spherical aberration compensating method, optical pickup spherical aberration focus offset compensating method, and optical pickup device

An object of the present invention is to attain stable tracking servo performance by suppressing an offset caused by a shift of an object lens or a tilt of a disk, despite the one-beam method which does not cause reduction in light quantity of the main beam. A diffraction grating is provided between a hologram and a light receiving section, and a diffraction efficiency of the diffraction grating is varied in a grating longitudinal direction. For example, if an incident light beam on the diffraction grating is shifted in the grating longitudinal direction, the quantity of received light in each light receiving section varies to cause offset. By performing tracking servo so as to cancel the change, it is possible to correct the offset, thereby attaining stable tracking servo performance.

Light integration unit, optical pickup device using the unit, and optical disk device

According to the present invention, an optical pickup device forms one main spot, a first subspot, and a second subspot by irradiation of light on an optical disk having a groove part and a land part. The optical pickup device includes operation circuits which indicate a deviation between each of the optical spots and a track, and &#x3b1; detecting means for detecting such an &#x3b1; value that a difference in absolute value between SPPand &#x3b1;SPPfalls in a preset range, where an AC amplitude of a push-pull signal of the first subspot is SPP, and an AC amplitude of a push-pull signal of the second subspot is SPP, wherein SPP&#x2212;&#x3b1;SPP(&#x3b1; is a constant) is a land/groove discriminating signal. With this, in the optical pickup device for recording and reproducing information on/from the optical disk having a land/groove part, it is possible to generate a land/groove discriminating signal and a tracking error signal without an offset, thereby performing excellent tracking control.

Optical pickup device

Part of reflected light from an optical disc enters a diffraction element (). The &#xb1;first-order diffracted light and zero-order diffracted light from the diffraction device () travel via a cylindrical lens () and a spot lens () and enter a photodetector (). If an objective lens shifts, a beam on the diffraction element () also shifts. Therefore, the intensity distribution of a spot of the zero-order diffracted light falling on light-receiving areas (A, B, C, D) of a four-part light-receiving element () becomes bright as a whole, while the intensity distributions of spots of the &#xb1;first-order diffracted light falling on light-receiving areas (E, F) of light-receiving elements () become dark as a whole. Thus, an optical pickup tracking error detecting method and an optical pickup device enabling good tracking control are provided.

Optical pickup tracking error detecting method and optical pickup device

Light emitted from a semiconductor laser is converted by a collimator lens into a collimated light, which enters into an objective lens of high NA and forms a condensed spot within an optical disk. The light emitted from the semiconductor laser is S-polarized light that oscillates in a direction perpendicular to the plane of incidence.

Beam shaping means may have a shaping ratio set to allow a light beam emitted from a semiconductor laser and having an elliptic intensity distribution to have an ellipticity of no more than two to obtain a spot achieving high light availability and reduced in size. Furthermore, the shaping ratio can be set to no more than 2.5 to allow a polalized-beam splitter (light separation means) and other components to be arranged in a converged flux passing between the semiconductor laser and a collimator lens.

A projection type color liquid crystal display apparatus includes: light collimation means for producing collimated light; main-wavelength band separation means for receiving the collimated light from the light collimation means and producing a plurality of light beams having respectively different wavelength bands and exiting at respectively different angles; sub-wavelength band separation means provided adjacent the main-wavelength band separation means, the sub-wavelength band separation means receiving the collimated light from the light collimation means and producing at least one light beam having the same wavelength band as the wavelength band of at least one of the light beams from the main-wavelength band separation means; a liquid crystal display device for receiving the light beams from the main-wavelength band separation means and the light beams from the sub-wavelength band separation means and modulating the light beams; and an optical system for receiving the light beams transmitted through the liquid crystal display device and thereby projecting an image.

Projection type color liquid crystal display device

A liquid crystal projector includes a light source for generating light; a liquid crystal display device for modulating the light; a projection optical system for projecting light modulated by the liquid crystal display device onto a screen; and an incidence optical system for dividing the light into at least two light components in an equal wavelength range and causing the two light components to be incident on the liquid crystal display device from different directions. The liquid crystal display device including a liquid crystal panel having a pixel apertures. The two light components incident on the liquid crystal display device enter the plurality of pixel apertures.

Color liquid crystal projector device

A light splitting and synthesizing device includes: a polarized beam splitter for splitting a white light into two polarized light beams and for directing the polarized light beams toward different directions; at least one half wave plate for rotating the polarization direction of one of the polarized light beams by 90 degrees so that the polarized light beams have the same polarization; and a synthesizing prism for synthesizing the polarized light beams into one beam. The synthesizing prism includes a substrate having a pair of parallel surfaces, on one of the surfaces an array of prisms with a vertical angle of 60 degrees being formed, the polarized light beams being incident on the array of prisms and being outgoing from the other surface. The half wave plate is disposed such a position that only one of the polarized light beams is incident thereon. Each of the polarized light beams incident on the synthesizing prism enters one face of a respective prism of the prism array and is totally reflected by an opposite face of the respective prism so as to be directed toward the outgoing surface of the synthesizing prism.

Light splitting and synthesizing device and liquid crystal display

The optical pickup of the invention includes a hologram mirror for directing an optical axis of a light beam emitted from a light source to be perpendicular to the recording face of a recording medium. The hologram mirror includes: a light transmissive substrate having a first surface and a second surface which are opposite to each other, the light beam from the light source entering the substrate from the first surface; a transmissive holographic element, formed on the first substrate, for diffracting the light beam incident thereon to generate a plurality of diffracted beams; and a reflective film, formed on the second surface of the substrate, for reflecting the diffracted beams, wherein the holographic element includes a blazed grating which is designed to make a predetermined one of the diffracted beams most intense.

Optical pickup

An optical recording and reproducing apparatus records two rows of a plurality of pit patterns with respect to one track by modulating two light beams and by converging the modulated two light beams in parallel onto the track. The plurality of pit patterns are detected and judged by a multiple hologram on which reflected object waves of all kinds of pit patterns are recorded, thereby enabling to carry out recording of information. With the arrangement, since multiple values recording and reproducing can be carried out with respect to a magneto-optical disk, the recording capacity becomes greater than the conventional case and the reproduced signal having little crosstalk can be obtained according to the present way of reproducing.

Optical recording and reproducing apparatus using a hologram to detect

A polarization detector includes a polarization diffraction element having a substrate with two facing surfaces which are placed in parallel with each other, a first diffraction grating formed on one surface of the substrate, and a second diffraction grating formed on the other surface of the substrate, with light being incident upon the first diffraction grating. Further, each grating pitch of the first diffraction grating and the second diffraction grating are nearly equal to a wavelength of the incident light. A limiting member is also included for limiting an incident region of the incident light with respect to the polarization diffraction element. The limiting member is formed on a light incident side of the first diffraction grating. Further, a converging lens is included for respectively converging light transmitted through the first diffraction grating and the second diffraction grating and light diffracted by the first diffraction grating and the second diffraction grating into different beam spots. Finally, a pair of photodetectors are included for detecting each optical intensity of the two beam spots converged by the converging lens.

Polarization detector

A display apparatus of the invention includes: a plurality of display devices arranged in one direction, each of the plurality of display devices having a display area; and a plurality of image transmission means corresponding to the respective display devices, one end face of each of the image transmission means being coupled to a display area of the corresponding one of the display devices, other end faces of the image transmission means corresponding to the adjacent ones of the display devices being in contact with each other, the plurality of image transmission means being bent toward the one direction in which the display devices are arranged. Alternatively, a display apparatus of the invention includes: a plurality of display devices disposed in two directions, each of the plurality of display devices having a display area; a plurality of image transmission means corresponding to the respective display devices, one end face of each of the image transmission means being coupled to a display area of the corresponding one of the display devices, other end faces of the image transmission means corresponding to the adjacent ones of the display devices being in contact with each other, some of the plurality of image transmission means each having inward facing slopes and outward facing slopes on two pairs of opposing faces, the outward facing slopes of the image transmission means being directed to a direction in which the corresponding display device has no adjacent display devices.

Display apparatus having a plurality of display devices

An optical pick-up device comprising an optical system including a light source and an optical diffraction grating element and a light receiving element, wherein the optical diffraction grating element guides the 0th-order diffracted lights of a light beam emitted from the light source onto a recording medium and guides the first-order diffracted lights of a reflected light from the recording medium onto the light receiving element to produce a plurality of focused light spots having the same light amount, wherein the optical diffraction grating element includes diffraction gratings having a configuration in which grooves and flat lands each positioned between the adjacent grooves are successively alternately formed, wherein the diffraction gratings have the same groove depth, groove width and groove tilt angle in order to obtain a constant 0th-order diffraction efficiency and first-order diffraction efficiency in the optical diffraction grating element while the pitches of the diffraction gratings are made different by setting a different land width for each diffraction grating.

Optical pick-up device having an optical diffraction grating element

An optical scan device comprising a light source and an optical diffraction grating element movable relatively to the light source, which is designed to substantially linearly scan a recording medium in a predetermined direction with a uniform light amount of a light beam emitted from the light source as the optical diffraction grating element moves relatively to the light source. The optical diffraction grating element comprising diffraction gratings having a configuration in which grooves and flat lands each positioned between the adjacent grooves are successively alternately formed, wherein the diffraction gratings have the same groove depth, groove width and groove tilt angle in order to obtain a constant 0th-order diffraction efficiency and first-order diffraction efficiency in the optical diffraction grating element while the pitches of the diffraction gratings are made different by setting a different land width for each diffraction grating.

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Tenri, Japan

Takahiro Miyake