Matsushita Electric Industrial Co., Ltd.

Panasonic Corporation

Tomotada Kamei

Hiroaki Yamamoto

Shin-ichi Kadowaki

Kousei Sano

Fumitomo Yamasaki

Akihiro Arai

Katsuhiko Yasuda

Hideki Hayashi

Sadao Mizuno

Jouji Anzai

Yutaka Murakami

Yoshiaki Komma

Hidenori Wada

Kenzo Ishibashi

Takao Hayashi

Tatsuo Ito

Hisashi Senga

Yohichi Saitoh

Shin-Ichi Kadowaki

An optical pickup according to the present invention includes an integrated circuit element (LDD)for driving first, second, and third semiconductor lasers, and. The LDDis shaped so as to have a rectangular principal face surrounded by one side, with a plurality of input/output pins being arranged along each side. The plurality of input/output pins include a first pin group connected to a blue-violet laserwhose oscillation wavelength is the shortest, a second pin group connected to a red laser, and a third pin group connected to an infrared laser. The wiring structure of the optical pickup includes a first transmission linefor connecting the first pin group to the blue-violet laser, a second transmission linefor connecting the second pin group to the red laser, and a third transmission linefor connecting the third pin group to the infrared laser, where the first transmission lineis shorter than both the second and third transmission linesand. Of the rectangular principal face of the LDD, the side along which the first pin group is provided is orthogonal to the side along which the second pin group is provided or to the side along which the third pin group is provided.

Optical pickup and optical disc device

An optical information apparatus of the present invention includes: an optical pick-up head including: a light source; a diffraction unit; a condensing unit; a beam splitter; a photodetector; and a tracking error signal generator. An optical recording medium has tracks arranged substantially at a constant pitch. An average of a pitch is tp. When a main beam is placed on the track, a first sub-beam and a second sub-beam are placed between the tracks. The tracking error signal generator performs a differential arithmetic operation with respect to signals output from a light-receiving portion receiving the main beam to generate a first push-pull signal, performs a differential arithmetic operation with respect to signals output from the light-receiving portions receiving the first sub-beam and the second sub-beam to generate a second push-pull signal, and performs a differential arithmetic operation with respect to the first push-pull signal and the second push-pull signal to generate a tracking error signal, in a case where an amplitude of the first push-pull signal obtained at the pitch tp is fluctuated when the light beam is scanned in a direction orthogonal to the tracks of the optical recording medium.

Optical pick-up head, optical information apparatus, and optical information reproducing method

In order to make it possible to reproduce information recorded on an optical recording medium without causing deterioration in the information, a semiconductor laser driving device include a semiconductor laser, a photodetecting element for receiving a part of light emitted from the semiconductor laser and converting the part of light into an electric signal corresponding to a light amount; a laser driving circuit for inputting a driving signal into the semiconductor laser in such a manner that an average value of the electric signal coincides with a given target value, and a high-frequency superimposing control section for controlling an amplitude of the high-frequency signal. The high-frequency superimposing control section controls the amplitude in such a manner that a peak-to-average ratio that is a ratio of a peak value of the electric signal with respect to the average value of the electric signal does not increase above a given reference value.

Semiconductor laser driving device, optical head device, optical information processing device, and optical recording medium

An optical head is provided with: an objective-lens-use opening that determines an aperture of the objective lens; a light-source light-quantity controlling opening that aperture-controls light that has been separated by the light separation device; a light detector that receives light that has been aperture-controlled by the light-source light-quantity controlling opening; and a light detector that receives light that has been reflected by the optical recording medium, and has an arrangement in which: the length of the optical light path from the spherical aberration correcting device to the objective-lens-use opening is made virtually the same as a length of the optical light path from the spherical aberration correcting device to the light-source light-quantity controlling opening, and the aperture of the light-source light-quantity controlling opening has virtually the same size as the aperture of the objective-lens-use opening. The objective of the present invention is to provide an optical head in which a signal outputted from the light quantity detection device is unchanged even when the spherical aberration correcting device is driven so that by using this signal, the quantity of light from the light source is set to an appropriate value.

Optical head and optical recording and reproducing apparatus

A photodetector, includes: a semiconductor chip that converts received light to an electric signal; and a resin body that encapsulates the semiconductor chip. The photodetector further includes a protective unit, and at least a light transmission area, through which the light passes, in a surface of the resin body on an incident side of the light is covered by the protective unit. Covering the light transmission area with the protective unit that is less in reactivity with light than the resin body can suppress deformation of the resin body due to light, thus suppressing deterioration of the optical characteristics of the photodetector.

Optical detector, optical head device, optical information processing device, and optical information processing method

An optical head reproduces optical disks of different disk plate thickness t(0.6 mm) or t(1.2 mm) by using light beams of two wavelengths and one object lens. An converging element comprises a central portion and outer portion, wherein the central portion has optimum design plate thickness of 0.6*tto tand the outer portion has optimum design plate thickness of 0.6 mm. By providing a step difference in the converging element, information can be recorded or reproduced for an information medium of disk plate thickness tand for an information medium of disk plate thickness t, in a state having small side lobes. Alternatively, a step difference is provided in the object lens, and optical distance Lfrom a second light source to a condensing optical system is set to 80 to 95% of optical distance Lfrom a first light source to the condensing optical system. Alternatively, only light of first wavelength is shielded or diffracted in a ring-like shape.

Converging element, optical head, and apparatus and method of optically recording and reproducing information

An optical head reproduces optical disks of different disk plate thickness thicknesses t1 (0.6 mm) or t2 (1.2 mm) by using light beams of two wavelengths and one object lens. An converging element comprises a central portion and outer portion, wherein the central portion has optimum design plate thickness of 0.6*t1 to t1 and the outer portion has optimum design plate thickness of 0.6 mm. By providing a step difference in the converging element, information can be recorded or reproduced for an information medium of disk plate thickness t1 and for an information medium of disk plate thickness t2, in a state having small side lobes. Alternatively, a step difference is provided in the object lens, and optical distance L2 from a second light source to a condensing optical system is set to 80 to 95% of optical distance L1 from a first light source to the condensing optical system. Alternatively, only light of first wavelength is shielded or diffracted in a ring-like shape.

To provide a laser driving apparatus which is inexpensive and has high reliability in spite of using a plurality of light sources, since a multi-wavelength light source is required for treating different kinds of optical disks such as CD, DVD or the like. In a two-wavelength LD apparatus including: a semiconductor laser ; a semiconductor laser ; and a photo detector , optical outputs of the semiconductor lasers are controlled by APC circuits on the basis of respective voltage values of variable resistors connected in series to the photo detector . Alternatively, in the two-wavelength LD apparatus including: the semiconductor laser ; the semiconductor laser ; and the photo detector , the optical outputs of the semiconductor are controlled by the APC circuits on the basis of respective intermediate potentials of variable resistors connected in parallel with the photo detector

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Neyagawa, Japan

Tomotada Kamei