Dynamic information storage or retrieval – Dynamic mechanism subsystem – Having power driven transducer assembly
Reexamination Certificate
2000-03-23
2002-03-05
Letscher, George J. (Department: 2652)
Dynamic information storage or retrieval
Dynamic mechanism subsystem
Having power driven transducer assembly
Reexamination Certificate
active
06353589
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a guide mechanism for guiding a pickup. For example, the present invention relates to a guide mechanism for guiding a pickup with respect to an information recording face of an optical disk when it is applied to an optical disk reproducing device or an optical disk recording device.
2. Description of the Related Art
Conventionally, an optical disk reproducing device such as a CD player is capable of accurately reading information recorded on a CD as follows. When the CD on which a row of pits having information are spirally recorded is rotated by a spindle motor, the row of pits form a track of information to be scanned. While the track of information is accurately followed in the radial direction of the disk by a pickup attached to a pickup guide mechanism fixed to a casing of the CD player, the row of pits to be scanned can be optically read in order. In this way, information recorded on the CD can be read.
FIG. 4
is a view showing the above conventional pickup guide mechanism. On the chassis
101
of the pickup guide mechanism
100
, there is provided a shaft presser
103
to which a rod-shaped guide shaft
102
, the rigidity of which is high, is attached. When a recessed portion of the shaft presser
103
comes into contact with one end portion of the guide shaft
102
, the guide shaft
102
can be positioned, and also when the other end portion of the guide shaft
102
is fixed by a countersunk head screw
104
screwed into a screw hole formed on the chassis
101
, the guide shaft
102
can be arranged over an opening formed on the chassis, so that the guide shaft
102
can be positioned in the radial direction of a disk, that is, the guide shaft
102
can be positioned in the direction of arrow A. In this way, the guide shaft
102
can be fixed at a predetermined position shown in FIG.
4
.
For example, as shown in
FIG. 4
, the shaft presser
103
is made of resin by means of molding, and the bottom portion of the shaft presser
103
is fixed onto the chassis
101
. Alternatively, the shaft presser
103
may be formed by raising a portion of the chassis
101
.
A pickup
105
is slidably supported by the guide shaft
102
. When a drive force of a carriage motor
106
is transmitted to a rack
108
, which is fixed to the pickup
105
, via a gear
107
, an objective lens
109
of the pickup
105
can be moved in the radial direction of the disk.
FIG. 5
is a view showing the guide shaft
102
fixed onto the chassis
101
by the countersunk head screw
104
. The profile of the head portion of the countersunk head screw
104
is formed into a substantial cone shape having a tapered face. Taper angle &thgr; of the tapered face of the head portion of the countersunk head screw
104
is 90° by the standard size according to JIS (Japanese Industrial Standard), and the allowance does not exceed 90°.
The central axis of the countersunk head screw
104
, which is screwed to the chassis
101
, is located at a predetermined position on central axis X of the guide shaft
102
as shown in
FIG. 4
, and the central axis of the countersunk head screw
104
makes a right angle with central axis X of the guide shaft
102
.
Therefore, when the countersunk head screw
104
is screwed to the chassis
101
, the highest portion of one end of the guide shaft
102
comes into contact with an inclined face (tapered face) of the head portion of the countersunk head screw
104
forming angle &thgr;. Therefore, the highest portion of one end of the guide shaft
102
is pushed by force F of the tapered face. In this case, force F of the tapered face is perpendicular to the tapered face.
Component force Fz of force F, the direction of which is vertical, fastens one end portion of the guide shaft
102
by the countersunk head screw
104
and the chassis
101
, so that the guide shaft
102
can be fixed onto the chassis
101
by this fastening force Fz. Component force Fxy of force F, the direction of which is horizontal, pushes the other end portion of the guide shaft
102
against the shaft presser
103
, so that the guide shaft
102
can be positioned in the radial direction of the disk by this component force Fxy of force F.
In this case, as can be seen in
FIG. 5
, an angle formed between force F, which is perpendicular to the tapered face, and component force Fxy, which is horizontal, is &thgr;/2. Accordingly, for example, when angle &thgr; of the head portion of the countersunk head screw
104
is a standard size (90°), the angle formed between force F, which is perpendicular to the tapered face, and component force Fxy, which is horizontal, becomes 45°. Therefore, the intensity of component force Fz and that of component force Fxy become equal to each other.
In the case where angle &thgr; of the head portion of the countersunk head screw
104
is formed in an allowance which deviates from the standard size, the angle formed between force F, which is perpendicular to the tapered face, and component force Fxy, which is horizontal, becomes smaller than 45°. In this case, an intensity of component force Fxy becomes a little lower than that of component force Fz.
When the guide shaft
102
receives this fastening force Fz and this pushing force Fxy, it can be fixed to a predetermined position on the chassis
101
.
When it is estimated that the CD player on which the pickup guide mechanism is mounted is incorporated into a vehicle or used as a portable CD player, it is necessary to give a sufficiently high intensity of fastening force so that the guide shaft
102
can not be easily disconnected from the chassis
101
even if it is given external vibration or shock caused when the CD player is carelessly dropped.
In this connection, as described before, since angle &thgr; of the head portion of the countersunk head screw
104
is 90°, the intensity of component force Fz and that of that of component force Fxy necessarily become equal to each other. Therefore, when the countersunk head screw
104
is screwed into the chassis
101
so as to provide a sufficiently high fastening force, the pushing force is also increased.
When the pushing force is increased, a load given to the shaft presser
103
is also increased. Therefore, it is impossible for the shaft presser
103
to withstand the load, and the shaft presser
103
is plastically deformed.
FIG. 6
is a view showing a state in which the shaft presser
103
is deformed as described above.
As shown in
FIG. 6
, when one end portion of the guide shaft
102
is pushed by force F′, which is sufficiently higher than force F, by the inclined face of the head of the countersunk head screw
104
, pushing force F′xy, which is sufficiently higher than pushing force Fxy, of a component force of force F′ is generated, and also pushing force F′z, which is sufficiently higher than pushing force Fz, of a component force of force F′ is generated.
As a result, the guide shaft
102
pushes the shaft presser
103
by pushing force F′xy. However, the shaft presser
103
can not withstand this pushing force F′xy. Therefore, the guide presser
103
is deformed being pushed by the guide shaft
102
. At the same time, the guide shaft
102
is pushed in the thrust direction by the inclined face of the head portion of the countersunk head screw
104
which gradually proceeds downward being screwed into the chassis
101
. As a result, the guide shaft
102
deviates from a predetermined position.
As a result, not only the shaft presser
103
of the pickup guide mechanism is damaged but also the chassis
101
is deformed under certain circumstances, and it becomes impossible for the guide shaft
102
to be stably fixed at the predetermined position on the chassis
101
.
For the above reasons, in the conventional pickup guide mechanism, only pushing force Fxy, the intensity of which is kept in a range by which the shaft presser
103
is not deformed, can be given to the guide shaft
102
. As a result, it is impossible for the guide shaft
102
to be fi
Anada Satoru
Kinoshita Hideki
Morikawa Kiyoshi
Ota Takashi
Togashi Jun
Letscher George J.
Pioneer Corporation
Sughrue & Mion, PLLC
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