Sony Corporation

Clarion Co

Hitoshi Okada

Katsumi Yamaguchi

Kazuki Takai

Katsuya Nozawa

Tomiji Tanaka

Hiroyuki Umezawa

Naoya Eguchi

Takahiro Takeda

Satoru Seko

Mikio Sugiki

Hiroyuki Ohkawa

Hidenori Muramatsu

Kimichika Yamada

Yoshihiko Goto

Koji Takasaki

Shinichiro Terada

Atsushi Fukumoto

Yukio Ito

Hiroo Takahashi

Masanobu Yamamoto

Shunsuke Furukawa

Hiroshi Ogawa

Kiyoshi Ohsato

Shinji Yamada

Masaaki Hara

Toru Nagara

Yasuhito Eguchi

Hideo Owa

Masahiro Kikuchi

Mitsuru Toishi

Tsutomu Maruyama

Toshiki Udagawa

Naoto Kojima

Susumu Tosaka

Kanji Murano

Osamu Kawakubo

Akira Sanpei

Takao Ihashi

Kazutatsu Tokuyama

Tamotsu Maeda

Takeo Kaji

Yohsuke Naruse

Masao Ito

Mikio Sigiki

A hologram reproducing apparatus includes a first reference light path leading laser light from a laser light source so that a hologram recording medium is irradiated with first reference light; a diffracted light path leading diffracted light, generated from the hologram recording medium by irradiation with the first reference light, to a light receiving element having a plurality of pixels; and a second reference light path leading second reference light, having the same polarization direction as that of the diffracted light, from the laser light source to the light receiving element. The second reference light path is provided with a phase modulating element so that the phase difference between the diffracted light and the second reference light in a light receiving surface of the light receiving element is adjusted within a predetermined range.

Hologram reproducing apparatus, hologram reproducing method, and phase modulating element

A hologram recording and reproducing device controls an optical beam output from an external cavity semiconductor laser to improve a diffraction efficiency. The hologram recording and reproducing device includes an external cavity laser, a photodiode, a laser drive circuit and a laser diode controller. The external cavity laser has a laser diode adapted to emit an optical beam that is used to generate data light and reference light with which a hologram recording medium is irradiated. The photodiode detects the amount of the optical beam output from the external cavity laser. The laser drive circuit supplies a current to the external cavity laser. The laser diode controller controls the laser drive circuit to ensure that a value obtained by integrating the detected intensity of the optical beam with respect to time over a predetermined period is equal to predetermined recording energy.

Hologram recording and reproducing device and method for recording hologram

An optical unit includes an acousto-optic deflector and a drive control unit. The drive control unit controls the acousto-optic deflector by changing a frequency of a voltage applied to an acousto-optic medium of the acousto-optic deflector to a frequency in a first frequency range during a first period representing a deflection control period and changing the frequency of the voltage to a frequency in a second frequency range different from the first frequency range during a second period representing a transmittance control period.

Optical unit, method for controlling drive, and holographic apparatus

A holographic recording/reproducing apparatus is adapted to split laser light into signal light and reference light and to record a hologram by illuminating a holographic recording medium with the signal light and the reference light and/or to reproduce the hologram by illuminating the holographic recording medium with the reference light. The holographic recording/reproducing apparatus includes a laser light source that emits the laser light, a measuring unit operable to measure the wavelength of the laser light, and a setting unit operable to measure the wavelength of the laser light while changing a current supplied to the laser light source, and to set the current supplied to the laser light source based on a measurement result such that the influence of a change in the wavelength of the laser light is minimized.

Method and apparatus for recording and/or reproducing a hologram

A hologram recording/reproducing device includes a laser light source emitting laser light; a spatial light modulator generating signal light and reference light from the laser light emitted from the laser light source, the signal light and the reference light traveling in a common light path; a first relay lens system including a first shielding plate at a focal position thereof and transmitting the signal light and the reference light generated by the spatial light modulator, the first shielding plate having a pinhole whose size is 1 to 2 times a Nyquist size; a phase modulating element disposed at a conjugate plane of the signal light and the reference light transmitted through the first relay lens system; an objective lens converging the signal light and the reference light transmitted through the phase modulating element on a hologram recording medium; and a light receiving system disposed between the phase modulating element and objective lens and receiving light returning from the hologram recording medium.

Hologram recording/reproducing device and optical unit

The present invention makes it possible to control a writing light quantity by selectively using a light quantity detection result S(C+D) obtained from areas C and D at the back side in the direction of scanning with laser beams when data is recorded onto an organic dye type recording medium, such as a CD-R (compact disk recordable).

Optical disk drive and optical disc recording method

A method of tracking servo for an optical pickup device comprises the steps of generating each individual push pull signal (an SPP signal, an SPP signal and an MPP signal) with a photo detector composed of a main photo detector having four photo-detecting sections crosswise and two side photo detectors having respectively two photo-detecting sections left and right, and generating a tracking error signal (a DPP signal) on the basis of operational output from the push pull signals resulting from respectively canceling the amounts of DC offset produced in each of the push pull.

Method of tracking servo for optical pickup device

A battery protection circuit has a condition detecting circuit which detects a voltage across a secondary cell or cells and compares the detected voltage with a reference voltage to detect an overdischarged condition or an overcharged condition of the secondary cell or cells. A control unit controls a first switching element for cutting off a discharging current and a second switching element for cutting off a charging current based on a detected condition of the secondary cell or cells. A third switch element cuts off electric power supplied to the condition detecting circuit. The third switch element is rendered nonconductive when the overdischarged condition is detected by the condition detecting circuit.

Battery protection circuit

An optical recording and/or reproducing apparatus comprising a light beam generator, a photodetector, an optical path forming device for causing a light beam from the light beam generator to impinge upon an optical disc and for guiding the light beam emanating from the optical disc to the photodector, and a signal generating circuit block operative to obtain based on a detection output obtained from the photodetector a first signal representing a tracking condition of the light beam in relation to a record track portion on the optical disc and a second signal different in phase by substantially ninety degrees from the first signal and to produce a tracking error signal which satisfies the following equation:

Optical recording and/or reproducing apparatus

In an apparatus and method for optically recording on an optical disk a television signal comprised of a color image signal and an audio signal; one horizontal period portion of an original luminance signal and one horizontal period portion of two original color difference signals from a standard television signal are time-base-compressed to generate a time-base-compressed video signal for one horizontal period, the audio signal is digitized and time-base-compressed, and then the time-base-compressed digital audio signal and the time-base-compressed video signal are time-division-multiplexed with each other and recorded on the optical disk.

Apparatus and method for recording a color television signal on an

In a tape player configured to wind a tape pulled out of a cassette onto a rotary head to play the tape, a tension mechanism includes a mode member to control the position of a tension control member according to a selected tape mode so as to establish relative contact between a tension member and a tape under a constant pressure in a play mode and separate them in a stop mode.

Tape tension mechanism

This invention relates to a focusing error detection circuit employed in an optical pickup of an optical disk apparatus or the like. The laser light received from the recording medium is detected by a photodetector and processed in a focusing error computing device to form a first focusing error signal. The first focusing error signal is sampled and held at the timing of periodic turn-off of the laser beam and the sampled-and-held signal is subtracted from the first focusing error signals to produce a second focusing error signal. The second focusing error signal is freed of adverse effects caused by factors, such as temperature changes of the focusing error computing device thereby enabling the accurate focusing servo control of the optical pickup device.

Focus error detecting circuit for disk player

A rotation control for a magnet used in a magneto-optical recording system having a first coil that rotates a permanent magnet to invert the polarity of its magnetic field applied to an optical recording type disc and a second coil provided at the position displaced from the central line of the first coil and for applying a driving force to the permanent magnet when the permanent magnet begins to rotate, wherein the permanent magnet can be settled in quite a short time after it is inverted in polarity by controlling a drive current applied to the second coil.

Device for controlling rotation of a magnet used in a magneto-optical

A tape unloading mechanism which includes a frictional arrangment for adjusting torque of reel bases is configured to interrupt a frictional motion of the frictional arrangment in the tape unloading mode to ensure a reliable tape winding operation.

Mode changing mechanism for a tape player

Growing community of inventors

Chiba, Japan

Hitoshi Okada