Pioneer Electronic Corporation

Sakashi Ootaki

Masayuki Iwasaki

Masakazu Ogasawara

Kiyoshi Tateishi

Junichi Furukawa

Yoshitsugu Araki

Hideki Hatano

Takashi Yamaji

Tomomitsu Kouno

Masami Nishida

An optical pickup includes: a light source, an object lens, and an aberration correction unit for correcting aberration by giving a phase difference to a light beam. The aberration correction unit corrects astigmatism caused by an optical system of the optical pickup.

Optical pickup, aberration correction unit and astigmatism measurement

An LCD panel will rotate based on an external control signal by a prescribed angle such portion of light flux, that enters an objective lens, corresponding to a predetermined incident point and, at the same time, will change by a prescribed length an optical path of this portion of optical flux whose aberrations are in excess of a prescribed standard value. It is thus possible to compensate the wave-front aberrations due to the differences in the effective optical-path length and also to control the effective numerical aperture of the objective lens by utilizing linearly polarized light as the light to be emitted from the laser beam source. It is also possible to compensate the aberrations due the differences in the substrate thickness of the optical recording medium and those due to a tilt of the optical recording medium.

Wave-front aberration compensation unit, wave-front aberration

A compatible optical pickup for DVD and CD in which, between an objective lens and a polarizing beam splitter, there is disposed a transmission type liquid crystal panel which has transparent electrodes formed with an aperture pattern having a predetermined configuration which gives transmitted light a phase difference, such as 1/4 of a wavelength or an odd multiple thereof. The liquid crystal panel is tilted and disposed with a predetermined angle between an objective lens and said laser light source for causing a phase difference in a laser beam emitted from said laser light source, whereby the liquid crystal panel is tilted with a predetermined pretilted angle .theta. so that liquid crystal molecules are aligned, in perpendicular relation to (for P-type liquid crystal) or in parallel relation with (for N-type liquid crystal) an optical axis of the objective lens at the time when no voltage is applied.

Optical write/read head with a pretilted liquid crystal panel

An optical pickup which is designed to correct coma aberration and spherical aberration as well as aberration caused by the relative positional deviation of an objective lens to an aberration correcting liquid crystal panel by using this liquid crystal panel and which is thus compatible to both DVDs and CDs. In the optical pickup having at least a laser light source and an objective lens, an aberration correcting liquid crystal panel is arranged on the optical axis of a laser beam and a transparent electrode of this liquid crystal panel is divided into segments in a predetermined pattern like the cross pattern of a chessboard, and voltages to be applied to the individual segments are variably controlled by a liquid crystal panel controller to alter the refractive index of each segment, thus correcting aberration.

Optical pickup with aberration correcting panel including a liquid

An optical pickup of a compatible type which can be switched for a DVD and a CD by a completely electrical control without the need of a mechanical moving device or the like and is suitable for the reduction in size and also has an excellent efficiency in the use of light. A liquid crystal panel of a transmission type which gives a phase difference of a 1/4 wavelength or a wavelength that is an odd number multiple of 1/4 wavelength to a transmission light and has a transparent electrode having an aperture pattern of a predetermined shape is used and the liquid crystal panel is arranged so that its plane of polarization crosses a plane of polarization of a polarization beam splitter at a predetermined angle. An applied voltage to the transparent electrode is controlled so that the whole surface of the liquid crystal panel functions as a 1/4 wavelength plate during a reproduction operation or a recording operation of the DVD and only the aperture pattern portion functions as a 1/4 wavelength plate during the reproduction operation of the CD.

Optical pickup used with both DVD and CD

An optical pickup device which makes a numerical aperture of an object lens in a radial direction of an optical disk smaller than that in a tangential direction to a track on the optical disk. With this feature, a spot diameter in the tangential direction to the track becomes smaller than that in the radial disk in the data recorded surface thereof, and it is possible to prevent degradation of a MTF as well as to accurately read data recorded in the high-density optical disk.

Optical pickup device

A reflecting type liquid crystal display apparatus which can prevent an unnecessary rotation of the plane of polarization in a polarizing prism. The apparatus has: a reflecting type liquid crystal device for changing a polarizing state in accordance with an image, thereby reflecting an incident light; and a polarizing prism 50 for emitting the light of a predetermined polarized component in the incident light from a light source at a surface of polarization operation, for inputting the emitted light into the reflecting type liquid crystal device, for emitting the light of a predetermined polarized component in the incident light from the reflecting type liquid crystal device, thereby obtaining a projection image. A plate for compensating the polarizing state having a surface in an oblique direction different from an oblique direction of the surface of polarization operation and also having a predetermined phase difference is arranged in an optical path between the reflecting type liquid crystal device and the polarizing prism.

Reflection type liquid crystal display apparatus which prevents rotation

A photo-conductive liquid crystal display in which the liquid crystal light valve and the electroluminescence element are disposed integrally with each other. The photo-conductive liquid crystal light valve is arranged such that a pair of transparent electrodes are disposed on the outside of a lamination of a photo-conductive layer and a liquid crystal layer, and an electroluminescence element is disposed on the outside of the transparent electrode which is disposed on the writing side of the device.

Growing community of inventors

Saitama, Japan

Sakashi Ootaki