Dynamic information storage or retrieval – Control of storage or retrieval operation by a control... – Mechanism control by the control signal
Reexamination Certificate
1999-01-07
2001-05-01
Huber, Paul W. (Department: 2651)
Dynamic information storage or retrieval
Control of storage or retrieval operation by a control...
Mechanism control by the control signal
C369S047470, C369S053300
Reexamination Certificate
active
06226242
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to disk recording or playback devices by which information is recorded on or reproduced from disks serving as recording media, and a method of controlling the pickup of the device.
BACKGROUND OF THE INVENTION
FIG. 2
shows a mechanism deck
2
already known for use in such disk recording or playback devices. The deck
2
comprises a chassis
4
formed with an opening
40
, a guide rod
41
extending across the opening
40
, and a turntable
31
provided at an end portion of the opening
40
for rotating a disk
6
. Mounted on the guide rod
41
is a pickup
3
having an object lens
30
and movable toward the turntable
31
. The pickup
3
is driven by a motor M
1
on the chassis
4
by way of a gear train
32
and worm
33
.
Although the voltage to be applied to the motor M
1
is variable to alter the drive torque thereof in the following description, the motor M
1
may be so adapted that the drive torque thereof can be altered by varying the current to be supplied thereto.
The disk
6
is housed in a cartridge
60
, which is provided with a slidable shutter
61
. With the cartridge
60
placed on support pins
42
on the chassis
4
, the shutter
61
slidingly moves to expose the lower surface of the disk
6
, whereupon a beam is projected from the lens
30
of the pickup
3
for recording or playback.
With reference to
FIG. 3
, the disk
6
is 64 mm in outside diameter and 29 mm in inside diameter. An inner peripheral region ranging from 29 mm to 32 mm in diameter is referred to as a lead-in area A, a region ranging from 32 mm to 61 mm in diameter as a program area B, and an outer peripheral region ranging from 61 mm to 64 mm in diameter as a lead-out area. Recorded in the lead-in area A is a so-called TOC (table of contents) which is a summary of the information recorded on the disk. The pickup
3
moves along a phantom line R
1
(see
FIG. 3
) through the center of the disk and the lens
30
on the pickup
3
.
As shown in
FIG. 4
, the disk of the type described has grooves called pregrooves
62
and formed over the entire area of its rear surface circumferentially thereof except the lead-in area (A, in FIG.
3
), the grooves extending slightly in zigzag. An address is provided every distance of movement of the pickup
3
along the zigzag groove for 13.3 msec, and is detectable even when no data is recorded on the disk. The grooves are approximately equidistantly spaced from inside outward. In place of pregrooves
62
, pits (not shown) are formed in the lead-in area.
The distance of movement for 13.3 msec is termed one sector, and
36
sectors correspond to the distance of one cluster. The disk has the location of 0 cluster on a phantom circle with a diameter of 32 mm. The smallest cluster is −134 cluster on a phantom circle with a diameter of 29 mm, and the largest cluster is 2060 cluster on a phantom circle with a diameter of 64 mm.
For accurate reading of signals from the disk, it is necessary to activate a focus servo, tracking servo and speed servo. The term the “focus servo” refers to a servo for delicately moving the lens
30
of the pickup
3
upward or downward for focusing a beam from the lens
30
on the rear surface of the disk. The known astigmatism method is mainly used for the servo. The term the “tracking servo” refers to controlling the position of the beam so that the focus of the beam correctly tracks the pits in the disk. The known beam method or push-pull method is used. The term the “speed servo” refers to controlling the rotation of the disk so as to give the disk a constant linear speed, i.e., 1.4 m/sec. The servo is activated based on the difference between a reference signal on the disk and a reference signal on the circuit.
For recording or playback, a beam spot is first projected on the rear surface of the disk from the lens
30
of the pickup
3
, and the focus servo is activated to move the lens upward or downward and focus the beam on the disk rear surface. The lens
30
is thereafter moved along the rear surface of the disk, and the tracking servo is activated for the beam to track the recording groove correctly, with the speed servo activated. After address data is read, the lens
30
or the pickup
3
is moved to move the beam to a desired address to read a desired signal.
In the following description, activating the focus servo, tracking servo and speed servo in sequence will be referred to as “turning on the servo,” and inactivating the servos as “turning off the servo.”
However, the disk recording or playback device of the type described has the following problems.
It is desired that the device be adapted for so-called random access, such that the pickup
3
is quickly movable to a desired position for the start of playback. However, if the pickup
3
is moved at an excessively high speed, the target position is not detectable accurately, for example, because the pickup
3
moves past the position. Further if the speed of movement is excessive, another problem arises, for example, in that the gear train
32
shown in
FIG. 2
for transmitting power from the motor M
1
to the pickup
3
gives off an increased noise.
The speed of movement of the pickup
3
varies from device to device due, for example, to fluctuations in the drive torque of the motor M
1
and the load torque of the gear mechanism, with the result that some pickup
3
are too great in the speed of movement while others are too slow. Such variations become pronounced in random access.
FIG. 11
shows a closed loop proposed in view of the above problems (see JP-A-195045/1996). The closed loop has an intermediate point
90
provided between a motor M
1
and a driver circuit
9
for energizing the motor M
1
. The load
91
due to the mechanical load of the motor M
1
and to the counterelectromotive force resulting from the rotation of the motor M
1
is converted as at
92
to a voltage, which is applied to the intermediate point
90
, whereby a voltage corrected by considering the load
91
is applied to the motor M
1
to stabilize the speed of the motor M
1
. However, the circuit becomes complex in construction because the motor M
1
is controlled by the closed loop every revolution thereof.
SUMMARY OF THE INVENTION
An object of the present invention is to prevent the speed of movement of the pickup from varying from device to device and ensure stabilized recording or playback by a simple circuit construction.
The present invention provides a pickup control method for a disk recording or playback device comprising a pickup
3
having a lens
30
for projecting a beam onto a signal recording surface of a disk and movable along a phantom line R
1
joining the center of the disk and the lens
30
, a motor M
1
for moving the pickup
3
, arithmetic means for calculating the position of the pickup
3
on the disk from data read by the pickup
3
, and timer means
13
for measuring the time taken for the movement of the pickup
3
.
Predetermining for controlling the operation of the pickup
3
are a specified distance L
1
the pickup
3
is to be moved and a standard period of time T
1
required for the movement over the distance L
1
.
First, the motor M
1
is energized with a voltage or current of given value a first to move the pickup
3
the specified distance L
1
, the time taken for the movement is measured by the timer means
13
, and the ratio of the measured movement time to the standard time T
1
is calculated.
The voltage or current b to be supplied to the motor M
1
is calculated from the ratio and the value a to approximate the pickup movement time to the standard time T
1
, and the voltage or current value b for the motor M
1
is temporarily stored when the movement time is approximate to the standard time T
1
. The voltage or current of the stored value b is supplied to the motor M
1
when the pickup
3
is to be moved subsequently.
According to the control method of the invention, the pickup
3
of every device is moved, the voltage or current value for moving the pickup
3
is corrected based on the time t
Armstrong Westerman Hattori McLeland & Naughton LLP
Huber Paul W.
Sanyo Electric Co,. Ltd.
LandOfFree
Disk recording of playback device and method of controlling... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Disk recording of playback device and method of controlling..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Disk recording of playback device and method of controlling... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2527159