Sharp Kabushiki Kaisha Corporation

Hideji Morita

Yasusi Seike

Norihiro Kurokawa

Yoshifusa Fujioka

An optical recording and reproducing device of the present invention has an objective lens designed so as to form a light spot with a set diameter on a DVD, while to form, on a CD, a light spot with a set diameter different from the above diameter. Respective working distances WD1 and WD2 with respect to the DVD and the CD are set in accordance with deflection standards F for the DVD and the CD, respectively. By doing so, as compared with conventional cases where the deflection standards F are not taken into consideration, the working distance WD1 is decreased. As a result, the device is thinned, compared with the conventional cases.

Focusing distance of an objective lens according to a vertical deviation

A masking member is provided so as to move in an interlocked manner with a shift of an objective lens designed for a high-density disk. Since the masking member reduces an effective numerical aperture (NA) of the objective lens, and greatly reduces affection of aberration, the objective lens allows a CD whose substrate is thicker than that of the high-density disk to be stably reproduced. Also, for example, even when the objective lens moves in a track direction of the high-density disk or CD, the masking member follows that movement. Therefore, a suitably sized light spot is formed on a signal surface of the high-density disk or CD. Especially, a light flux having passed inside the masking member with relatively small aberration is used to form a suitably sized light spot on the signal surface of the CD.

Optical head including ring-shaped light blocking or light

In an optical recording and reproducing device, an aperture member is provided in a region between an objective lens and a reflection mirror so as to be freely pushed into and pulled out of a light flux, and a masking member is provided on the objective lens. The masking member has an inside diameter smaller than an aperture diameter of the aperture member, and has an outside diameter greater than the aperture diameter of the aperture member. The aperture member has an outline size greater than a size of an aperture of an objective lens holding member. Therefore, an effective numerical aperture of the objective lens is determined in accordance with the inside diameter of the masking member in the case where the aperture member is placed in the light flux, whereas the effective numerical aperture is determined by the aperture of the objective lens holding member in the case where the aperture member is not placed in the light flux. With this arrangement, stable reproduction of a compact disk without being affected by a shift of the objective lens is enabled, while reproduction of a high-density disk is also enabled.

Optical recording and reproducing device

A disc reproduction apparatus includes a disc reproduction assembly and a tray accommodating unit positioned at either side of the disc reproduction assembly on the upper face of a main body of the apparatus. A disc tray group including a plurality of disc trays sequentially connected in series by a joint is provided in a movable manner between the tray accommodating units at either side of the disc reproduction assembly. In accordance with the travel of the disc tray group, one disc tray is selectively positioned in the disc reproduction assembly and the remaining disc trays are stored in the tray accommodating units. According to this structure, the number of loadable discs can be increased without unduly increasing the size of the entire apparatus and the complexity of the selecting mechanism.

Growing community of inventors

Higashihiroshima, Japan

Hideji Morita