Sanyo Electric Co., Ltd.

Masami Shimizu

Ryoichi Kawasaki

Yoichi Tsuchiya

Shuichi Ichiura

Seiji Kajiyama

Yasuyuki Kanou

Koichi Tada

Toshio Harada

Kozo Suzuki

Tomio Uchida

Noriyoshi Oyama

Noriyoshi Ooyama

Kouzou Suzuki

An apparatus for discriminating optical disks has an optical pickup provided with an objective lens having an effective numerical aperture of 0.55 to 0.65, which can compatibly reproduce information from a CD and an SD. The apparatus discriminates presence/absence of waveforms of two focus error signals detected when the effective numerical aperture of the objective lens is set at 0.55 to 0.65 and 0.20 to 0.45 respectively in a process of performing focus servo control, thereby discriminating various types of optical disks from each other. Thus, optical disks having different substrate thicknesses, different track pitches, different minimum pit lengths and different reflectivity can be quickly and simply discriminated from each other.

Apparatus for discriminating optical recording media of different thicknesses from each other and reproducing information therefrom

Apparatus for discriminating optical recording media of different

A small-sized electric mechanical transducer wherein plates are disposed to surround a bobbin in association with yokes. Magnetic passages are formed among the plates. Each of a pair of magnets drives the bobbin in accordance with the electric signals input into the driving coil. Also, an optical type pickup apparatus positively capable of the signal reading operation in which the lens holder is not out of shape even if the lens holder is driven in the focusing direction and the tracking direction, because the gravity center of the lens holder is conformed to the action point of the resultant force of the forces to be produced by the control signals to be input into the driving coil, and by the magnetic field of the magnetic circuit.

Electric mechanical transducer and optical type pickup apparatus driven

A optical type pickup apparatus wherein the center of gravity of the lens holder coincides with the action point of the resultant force of the forces to be produced by the control signals input into the driving coil and by the magnetic field of the magnetic circuit. Thus, this apparatus may be provided which is capable of a signal reading operation wherein the lens holder is not out of shape even if the lens holder is driven in the focusing direction and the tracking direction. The present invention is capable of reading the signals from the signal record medium and advantageous in making the apparatus smaller, because the combination between the lens holder and each of a plurality of wires is kept away by a given amount from the end secured to the frame of the wire from the mid-point position between both the ends of the frame to control the inclination when the lens holder has moved in the focusing direction and the tracking direction to normally render the posture of the objective lens proper with respect to the disc face.

Optical type pickup apparatus with lens holder supported by frame wires

An optical pickup device in which a laser light source is so disposed that one of two dividing lines of a photo-detector having at least four sensing portions symmetrically divided by the dividing lines so as to detect focusing deviation of a light beam onto a signal surface of a record disc, is aligned with the tangential direction of the signal track at the portion where the light beam is projected onto the signal surface, whereby the optical pickup is free from a wrong focusing control due to erroneous detection even during track jumping.

Optical pickup device wherein the astigmatic converged beam spot is

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Gunma, Japan

Masami Shimizu