Dynamic information storage or retrieval – Information location or remote operator actuated control – Selective addressing of storage medium
Reexamination Certificate
1999-01-26
2002-08-06
Neyzari, Ali (Department: 2653)
Dynamic information storage or retrieval
Information location or remote operator actuated control
Selective addressing of storage medium
C369S044280
Reexamination Certificate
active
06430120
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to methods and systems for controlling a disc player after power has been interrupted and then reconnected. More specifically, the inventive method and apparatus provides a resume function for the disc player that restores the position of the disc pickup to its position prior to the power interruption.
BACKGROUND OF THE INVENTION
Compact discs (referred to as “CD's”)carry data recorded on a track that is in a spiral or concentric form on a recording medium. In a conventional CD player, a pickup device is conveyed radially across the CD. The pickup device is an optical pickup that relies upon radiating a laser beam onto the track and detecting changes in the reflected beam. Electronics within the CD player converts the sensed reflected signal to a digital bit stream. For an audio CD, this digital bit stream is subsequently converted to an audio signal.
One typical construction for a CD player is shown in FIG.
1
. The disc player includes a motor
10
that rotates a platen supporting the compact disc D. A disc control microprocessor
12
controls the operation of the motor
10
to maintain a controlled speed of rotation for the disc D.
An optical pickup
14
is disposed beneath the recorded surface of the disc D. Signals generated by the optical pickup
14
can be provided to signal processing electronics within the disc player (not shown). In one type of CD player, the optical pickup
14
is carried by a fine actuator
16
that is operable to translate the pickup back and forth in a track access direction. This track access direction is substantially radial relative to the disc D. The fine actuator
16
is mounted to a carriage
18
that is propelled by a coarse actuator
20
through a transmission mechanism
22
. The coarse actuator
20
can constitute a servomotor that operates the transmission mechanism
22
to translate the carriage
18
in the track access direction. In certain embodiments, the transmission mechanism
22
can constitute a rack and pinion device or a rotating drive screw.
Operation of the coarse actuator and transmission mechanism
22
provides coarse movement of the carriage
18
, and consequently the optical pickup
14
, relative to the disc D. On the other hand, the fine actuator
16
provides for smaller incremental motion of the optical pickup
14
relative to the disc D. In other words, the fine actuator
16
provides a finer tolerance movement of the pickup than is accomplished by the coarse actuator
20
.
The fine actuator
16
can constitute an electromagnetic coil apparatus. Voltage applied to the coil apparatus causes the fine actuator
16
to translate the optical pickup
14
relative to the carriage
18
. In the illustrated system, the fine actuator
16
maintains the optical pickup
14
in a neutral position in the absence of an impressed voltage to the actuator. A spring element
15
can be disposed between the pickup
14
and the carriage
18
to restore the pickup to the neutral position once the fine actuator
16
is de-energized. In contrast, the coarse actuator
20
does not maintain a neutral position for the carriage
18
. Instead, the carriage
18
remains in its then current position when the coarse actuator
20
is de-energized. Typically, the coarse actuator
20
is servo-locked so that the carriage
18
will not change position even when the disc player is vibrated or jarred.
The operation of the fine actuator
16
is governed by a fine actuator controller
26
. Signals are transmitted to and from the fine actuator
16
and actuator controller
26
by way of signal lines
25
. Likewise, the coarse actuator
20
is governed by a coarse actuator controller
28
. Signals pass on lines
27
between the controller
28
and the coarse actuator
20
. The disc control microprocessor
12
transmits signals to and from the actuator controllers
26
and
28
along lines
29
. For example, the disc control microprocessor
12
can provide a skip function for the disc player in which the optical pickup
14
is transferred between tracks of the recorded disc D. In this instance, the microprocessor may direct the coarse actuator controller
28
to undertake a gross movement of the carriage, and then command the fine actuator controller
26
to produce a smaller incremental movement until the pickup is positioned beneath the desired track. The optical pickup
14
can include a position sensor (not shown) that provides information to the disc control microprocessor
12
to ascertain the current track of information on the disc D.
The mechanics of the movement of the optical pickup
14
are depicted sequentially in FIG.
2
. The figure presents a block diagram representation of the carriage
18
supporting the fine actuator
16
, which is operable to translate the optical pickup
14
. The carriage
18
is driven by the transmission mechanism
22
in response to the coarse actuator
20
. As shown in the first position of FIG.
2
(
a
), the optical pickup
14
is in its neutral position N. Preferably, this neutral position is generally centered relative to the carriage
18
and can be maintained by the spring
15
.
When a voltage is applied to the fine actuator
16
, the optical pickup
14
translates from the neutral position N to a position shown in the next figure of the sequence, FIG.
2
(
b
). As the voltage impressed to the fine actuator
16
gradually increases, the actuator gradually moves the optical pickup
14
to its limit position LP, as depicted in FIG.
2
(
c
). In the illustrated embodiment, the limit position is near one end of the carriage
18
and is disposed apart from the original neutral position N.
At the point in which the optical pickup
14
has reached its limit position, the pickup can be translated no further by the fine actuator
16
. Thus, in order for the pickup to continue to radially traverse the surface of the recorded disc D, the carriage
18
must then be translated. The movement of the carriage
18
by operation of the coarse actuator is depicted in FIG.
2
(
d
). As the carriage is translated, the optical pickup
14
remains in its absolute position LP relative to the disc D. Thus, the disc control microprocessor
12
must decrease the applied voltage to the fine actuator
16
so that the spring
15
draws the optical pickup
14
toward its centered neutral position N relative to the carriage
18
. At the same time, and in a coordinated fashion, the carriage
18
is translated in an opposite direction radially outward relative to the disc D. With this coordinated movement, the optical pickup
14
is returned to its neutral position, now designated N′, as shown in FIGS.
2
(
d
) and
2
(
e
). At that point, then, the fine actuator can be activated to further translate the optical pickup toward its new limit position.
As depicted in the sequence of steps in
FIG. 2
, the optical pickup
14
is consistently maintained to one side of the neutral position N. Alternatively, an opposite voltage can be applied to the fine actuator
16
to draw the pickup
14
to the left of the neutral position. In either case, the relocation of the carriage
18
relative to the optical pickup
14
requires cooperative control of the fine actuator controller
26
and the coarse actuator controller
27
so that the coarse movements of the carriage
18
do not disrupt the continuous reading of data from the disc D.
One problem faced by compact disc players arises when power to the various driving components is interrupted, or cut-off, and then subsequently restored. When power is interrupted In disc players having a spring-centered fine actuator, the lens may spring back over more than a minute of disc play time. On the other hand, CD players having only coarse actuators that can be servo-locked in position are generally difficult to tune to accurately and continuously read the recorded data in the small tracks of a compact disc.
A fine actuator, such as the actuator
16
depicted in
FIG. 1
, permits accurate positioning and tracking of the optical pickup
14
relat
Carman Dan Darryl
Chritz, Jr. Donald James
Pressgrove James Robert
Delphi Technologies Inc.
Funke Jimmy L.
Neyzari Ali
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