Optical disk player

Details Optical disk player Optical disk player

1998-12-28

2001-04-17

Ometz, David L. (Department: 2652)

Dynamic information storage or retrieval

Dynamic mechanism subsystem

Specified detail of transducer assembly support structure

Reexamination Certificate

active

06219327

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates, in general, to optical disk players used for reproducing data recorded on optical disks and, more particularly, to an optical disk player capable of effectively protecting an optical pick-up objective lens from foreign substances, such as dust.
2. Description of the Prior Art
As well known to those skilled in the art, optical disks, such as laser disks (LD) or compact disks (CD), have a high density data recording capacity and are almost completely and effectively used for a lengthy period of time in comparison with conventional magnetic tapes or LP records.
In order to play such optical disks and thereby to reproduce recorded data, several types of optical disk players, such as laser disk players or compact disk players, have been used. Of the known optical disk players, the compact disk players (CD players) have been more effectively, preferably and widely used since the CD players are small-sized so as to be convenient to users while carrying the disk players.
The signal format for such optical disks has been typically set to a conventional CLV(constant linear velocity)-type format which has a constant linear velocity at the inside and outside circular tracts of the disk “D” as shown in FIG.
1
. As shown in the drawing, the inside section of a typical optical disk “D” is divided into a chucking place “a” free from any recorded data and a data place “b” having information and data about the disk.
A known optical disk player, used for operating the disks “D” having such a signal format, is shown in FIG.
2
.
The disk player generally comprises three parts: a pick-up base
1
, a turntable
2
and a pick-up unit
3
.
In the above disk player, the pick-up base
1
is for supporting a plurality of parts of the disk player, so that it has a flat configuration. Both a guide rail
1
a
and a guide shaft
4
are set on the base
1
in a way such that the rail
1
a
is spaced apart from and parallel to said shaft
4
. The above guide shaft
4
is held by a supporter
1
b.
The turntable
2
or a disk drive means is set on the top surface of the pick-up base
1
and is for seating an optical disk thereon. In such a case, the disk is moved to the turntable
2
by a disk tray (not shown). The above turntable
2
is designed to be rotatable at a high speed by a spindle motor
5
arranged under the pick-up base
1
.
The pick-up unit
3
is for reading the data recorded on the disk seated on the turntable
2
. An objective lens
3
a
is set on the top wall of the pick-up unit
3
and is used for focusing a laser beam onto a desired portion of the optical disk.
The pick-up unit
3
is slidably held on the guide rail
1
a
at one sidewall thereof and slidably passes through the guide shaft
4
at the other sidewall. The above pick-up unit
3
is designed to be slidable in a radial direction relative to the disk while reproducing the data recorded on the disk. In such a case, the pick-up unit
3
is moved by the rotating force of a feeding motor
6
, which is arranged under the pick-up base
1
. The rotating force of the feeding motor
6
is transmitted to the pick-up unit
3
through a transmission gear train “G”.
However, the above disk player is problematic in that the player may fail to stably or precisely read the data recorded on a disk. That is, the above optical disk player may undesirably cause an error while reading the recorded data of optical disks.
In the operation of the above disk player, an optical disk is moved from the outside to the inside of the player by a disk tray (not shown) prior to being seated on the turntable
2
. However, foreign substances, such as dust, may be easily introduced into the interior of the disk player during such a disk feeding action of the tray. Such foreign substances may stick on the objective lens
3
a
of the pick-up unit
3
, and cause the above-mentioned problem of data reading error.
That is, when foreign substances, such as dust, stick on the objective lens
3
a
of the pick-up unit
3
, the lens
3
a
fails to appropriately focus a laser beam, emitted from a laser diode (not shown) of the pick-up unit
3
, onto a desired point of the disk, but irregularly reflects the laser beam while reducing the optical efficiency of the pick-up unit
3
due to the foreign substances. This prevents the pick-up unit
3
from stably or effectively reproducing the data recorded on the disk.
In order to overcome the data reading error of the pick-up unit
3
due to the foreign substances, it is necessary to repeatedly clean the surface of the objective lens
3
a
. However, since the pick-up unit
3
is set in the housing of the optical disk player, it is very difficult for users to clean the surface of the objective lens
3
a
. Furthermore, some optical disk players are designed to completely prevent the users from gaining access to the objective lens
3
a.
In an effort to overcome the above-mentioned problem, an optical disk player, which is designed to prevent foreign substances, such as dust, from undesirably sticking on the objective lens of the pick-up unit, is proposed as disclosed in Japanese Patent Laid-open Publication No. Heisei 6-274915.
The construction of the above Japanese optical disk player is shown in
FIGS. 3 and 4
of the accompanying drawings. As shown in
FIGS. 3 and 4
, the Japanese optical disk player
10
comprises a pick-up base
10
a
, a pick-up unit
13
and a pick-up drive means. In the above disk player
10
, the pick-up unit
13
is slidably held on the base
10
a
in a way such that the unit
13
is selectively slidable in a radial direction relative to an optical disk while focusing an optical beam onto a desired point of the disk and reproducing the data recorded on said disk. The pick-up drive means, comprising a feeding motor
14
and a transmission gear train
15
, moves the pick-up unit
13
in a radial direction relative to the optical disk.
In the above optical disk player
10
, a protection member
16
is provided on the pick-up unit
13
for selectively covering the objective lens
13
a
during a stop mode of the disk player. The above protection member
16
has an extension part
16
a
and is normally biased counterclockwise in the drawings by a spring
17
.
In the operation of the above optical disk player
10
, at a time the disk player
10
is stopped and returns the pick-up unit
13
to its waiting position by the pick-up drive means
14
and
15
, the extension part
16
a
of the protection member
16
comes into contact with a fixed stopper
18
of the base
10
a
, thus rotating the protection member
16
clockwise in the drawings while overcoming the biasing force of the spring
17
. Therefore, the protection member
16
covers the objective lens
13
a
of the pick-up unit
13
.
It is thus possible for the protection member
16
to prevent foreign substances, such as dust, from sticking on the objective lens
13
a.
In
FIGS. 3 and 4
, the reference numeral
6
denotes a contact switch which is selectively brought into contact with the pick-up unit
13
so as to selectively turn on or off the motor
14
of the pick-up drive means.
The above optical disk player
10
somewhat effectively prevents foreign substances, such as dust, from sticking on the objective lens
13
a
of the pick-up unit
13
due to the protection member
16
. However, the optical disk player
10
has a serious problem in that an operational error is generated at a time the data reproduction mode of the player
10
is started, and so the pick-up unit
13
regrettably fails to reproduce the recorded data of the disk.
The above-mentioned problem will be described in detail with reference to
FIGS. 1 and 5
.
As shown in
FIG. 5
, when letting the distance between the center of the turntable and the waiting position of the pick-up unit
13
or the outside edge of the disk's chucking place “a” be “L” and letting the distance between the center of the turntable and the outside edge of the disk's data place “b” be “l”, the difference between the two di

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