Dynamic information storage or retrieval – Information location or remote operator actuated control – Selective addressing of storage medium
Reexamination Certificate
1999-09-24
2001-01-16
Neyzari, Ali (Department: 2752)
Dynamic information storage or retrieval
Information location or remote operator actuated control
Selective addressing of storage medium
C369S053130, C369S044350
Reexamination Certificate
active
06175538
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to devices by which information is recorded on or reproduced from disks, and a method of adjusting the initial position of 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
, two guide rods
41
,
41
extending across the opening
40
, and a turntable
31
provided at an end portion of the opening
40
for rotating a disk. A pickup
3
having an object lens
30
is movably mounted on the two guide rods
41
,
41
. The pickup
3
is driven by a motor (not shown) on the chassis
4
. Provided inside the opening
40
close to the turntable
31
is a sensor switch SW for detecting the pickup
3
as brought closest to the inner periphery of the disk.
The disk
6
is housed in a cartridge
60
, which is provided with a movable shutter
61
. With the cartridge
60
placed on support pins
42
on the chassis
4
, the shutter
61
slidingly moves to expose the disk
6
, whereupon a beam is projected from the lens
30
of the pickup
3
on the disk rear surface to record or reproduce signals.
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 (outer periphery) in diameter as a lead-out area C. The lead-in area A is an area having recorded therein a so-called TOC (table of contents) which is a summary of the information recorded on the disk. For the recognition of the position of the pickup
3
, the lead-in area A invariably has signals recorded therein as will be described later. The program area B has recorded therein desired information such as music signals. Detection of a signal recorded in the lead-out area C by the pickup
3
indicates that the pickup
3
has moved out of the program area B beyond the outer periphery thereof.
In a standby state for recording or playback, the pickup
3
is designed to be positioned in the lead-in area A in contact with the sensor switch SW. This position will be referred to as an initial position. The pickup
3
reads the TOC data, recognizes the initial position and thereafter moves the beam spot to a desired address for recording or reproducing signals. For accurate reading of signals from the disk, it is necessary to activate a focus servo for focusing the beam on the disk, a tracking servo for accurately tracking record grooves in the disk and a speed servo for rotating the disk at a constant speed based on a synchronization signal recorded on the disk.
If no signal is recorded at the location on which the beam is projected first, the speed servo can not be activated because of the absence of the synchronization signal, consequently effecting no recording or playback operation. The pickup
3
needs to be positioned correctly in the lead-in area A initially before activating the speed servo.
However, the conventional device has the following problem.
Mass production of devices of the type described involves variations in the position or angle of the sensor switch SW as mounted on the chassis
4
, therefore entailing the likelihood that the pickup
3
will not be positioned correctly in the lead-in area when halted on pressing the sensor switch SW. It is also likely that the pickup
3
, which is driven by a motor (not shown), will not be located in the lead-in area initially even if the sensor switch SW is correctly installed in place because the distance the pickup
3
moves through inertia after pressing the sensor switch Sw until the pickup comes to a halt differs owing to variations in the drive force of the motor or to variations in the moving load of the pickup
3
. This problem may be overcome by checking the mechanism decks
2
individually, for example, for the installed position of the sensor switch SW, whereas this procedure requires time and labor.
SUMMARY OF THE INVENTION
An object of the present invention is to reliably position the pickup in the lead-in area when the pickup is in the standby state for recording or playback.
The invention provides a disk recording or playback device which comprises a pickup
3
movable along the signal recording surface of a disk for detecting signals and addresses on the disk, and a sensor switch SW for detecting the pickup
3
as brought to the inner peripheral side of the disk.
The flow charts of
FIGS. 10 and 12
show the outline of the present invention. First, a target region where the pickup
3
is to be positioned initially is provided in the lead-in area A of the disk.
The pickup
3
is moved from the inner periphery of the disk toward the outer periphery thereof, and caused to overrun further toward the disk outer periphery (S
3
) for a predetermined period of time (S
1
) after the sensor switch SW detects the passage of the pickup
3
.
The pickup
3
reads the address of point A on the disk upon the completion of overrun (S
5
), and is thereafter returned toward the inner periphery and halted upon the sensor switch SW detecting the passage of the pickup
3
.
The overrun time is corrected to a shorter period (S
11
, S
12
) if the address A is closer to the disk outer periphery than the target area. The overrun time is corrected to a longer period (S
10
, S
15
) if the address A is closer to the disk inner periphery than the target region. The movement of the pickup
3
toward the disk outer periphery is repeated again, and the overrun time is stored which eventually enables the pickup to reach the target region (S
19
).
When the overrun time is decreased to not longer than a reference time t
1
(S
16
) by repeating shortening of the overrun time and if the address A then read is closer to the disk outer periphery than the target area, the direction of overrun is reversed (S
17
), the pickup
3
is moved toward the disk inner periphery, shortening or lengthening of overrun time is repeated, and the overrun time is saved which eventually enables the pickup
3
to be positioned in the target region (S
19
).
Before recording or playback is started again, the pickup
3
is moved outward from the disk inner peripheral side and thereby moved from the position of detection of the pickup
3
by the switch SW for the stored period of overrun time.
Thus, when an overrun time is set for every recording or playback device to position the pickup
3
thereof in the target region in a standby state before recording or playback is started, the pickup is capable of accurately reading the TOC signals. This sets the pickup
3
in an ideal initial position to subsequently ensure a smooth recording or playback operation.
REFERENCES:
patent: 5878015 (1999-03-01), Schell et al.
patent: 6069857 (2000-05-01), Schell et al.
patent: 0 463 720 A2 (1992-01-01), None
Armstrong, Westerman Hattori, McLeland & Naughton
Neyzari Ali
Sanyo Electric Co,. Ltd.
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