Dynamic information storage or retrieval – Dynamic mechanism subsystem – Specific detail of storage medium support or motion production
Patent
1994-01-04
1997-02-04
Tupper, Robert S.
Dynamic information storage or retrieval
Dynamic mechanism subsystem
Specific detail of storage medium support or motion production
369264, G11B 360
Patent
active
056006241
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to an arrangement pertaining to CD-players and comprising a turntable which is intended for contact with a CD-disk and provided with a motor-driven shaft; and an optical unit by means of which a laser beam is projected onto the surface of the CD-disk as the unit scans the disk from its periphery to its centre, said unit detecting laser light which is reflected onto the unit subsequent to having been modulated with information stored on the disk.
In present-day CD systems, an optical disk is rotated around a central shaft of a drive motor. A laser beam is projected onto the disk surface with the aid of a lens, a reflective mirror or beam splitter, and a projection lens. The laser beam is modulated with the information stored on the disk and the modulated light is detected by a photodetector. The detector output signals are delivered to a processor for producing information signals and tracing or tracking signals. The laser beam source, the lens, the mirror, the projection lens and the detector together form an optical unit which is caused to move from the periphery of the disk in towards the disk centre with the purpose of reading the information stored on the disk.
More specifically, the disk is read at a constant speed, meaning that the disk drive motor must be rotated progressively to a higher speed as the optical unit moves in towards the centre of the disk. In turn, this assumes that the drive system has no appreciable mass, since otherwise the motor would not be capable of managing the requisite, continuous rapid changes in speed in an adequate fashion.
DISCLOSURE OF THE INVENTION
An object of the invention is to facilitate the work of the drive motor in the case of a drive arrangement of the kind defined in the introduction, and also to reduce mechanical disturbances and interference.
According to the present invention, this object is achieved by supporting the turntable and the motor-driven shaft on an air journal means.
According to one highly advantageous embodiment, at present preferred, the air journal means and the turntable and motor-driven shaft are combined to form an air journal unit, which enables, in particular, the optical unit and the air journal unit to be constructed so as to be separable in relation to one another.
In this regard, the optical unit may be incorporated in a lid which can be closed over the air journal unit. An attractive solution is achieved when the air journal unit and the drive motor are commonly fitted in a lid that can be closed over the optical unit.
Alternatively, the air journal unit may form part of a lid which can be closed over the optical unit and preferably also over the motor. A surprisingly simple embodiment of the air journal means is obtained when the turntable is mounted for rotation on a flat element or sunk into the surface of a flat element which has an air chamber connected to the undersurface of the turntable.
The invention can be applied with all conceivable positions of the drive motor. For instance, in addition to the aforedescribed, the drive motor may be incorporated in the air journal unit and may also drive the turntable by means of a belt drive.
It has been found in practice that a noticeable sound improvement can be obtained by journalling the turntable and its shaft on an air journal. This is because the invention provides smoother movement of the turntable and reduces the occurrence of mechanical disturbances, which in turn increases precision in focusing the laser beam.
BRIEF DESCRIPTION OF THE DRAWINGS
Exemplifying embodiments of the invention will now be described in more detail with reference to the accompanying drawings, in which
FIG. 1 illustrates in perspective a CD-player fitted with a first embodiment of the inventive arrangement, which includes a disk journalling unit;
FIG. 2 is an axial section view of the disk journal unit shown in FIG. 1;
FIG. 3 is an exploded view of the disk journal unit shown in FIG. 1; and
FIGS. 4-6 illustrate respectively second, third and fourth ex
REFERENCES:
patent: 3479038 (1969-11-01), Eisner
patent: 3561768 (1971-02-01), Castagna
patent: 4087095 (1978-05-01), Koda
patent: 4256312 (1981-03-01), Ikeda
patent: 4438510 (1984-03-01), Matsumoto
patent: 4507774 (1985-03-01), Marchant
patent: 4783717 (1988-11-01), Zeeman
Patent Abstracts of Japan, vol. 8, No. 51 p. 259, abstract of JP, A, 58-200403 (Maikuro Seiki K.K.) Nov. 22, 1983.
Miller Brian E.
Tupper Robert S.
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