Dynamic information storage or retrieval – Control of storage or retrieval operation by a control... – Control of information signal processing channel
Reexamination Certificate
1999-01-29
2001-11-20
Hudspeth, David (Department: 2753)
Dynamic information storage or retrieval
Control of storage or retrieval operation by a control...
Control of information signal processing channel
C369S044280
Reexamination Certificate
active
06320830
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an optical information reproduction device. More specifically, this invention relates to a device for optically reproducing information from a disk medium on which concentric or spiral tracks are disposed, the medium comprising identification information areas in which identification information representing address information and the like are shifted radially inward and radially outward each approximately by a predetermined distance with respect to a track center and user information areas in which user information and the like are recorded on the center of a track.
In recent years, it has been demanded that a memory means for storing information store image information, video information, and other voluminous information in comparison with the conventional textual information and sound information, and optical disks have been attracting attention as a response to the demand. Conventional recordable optical disks are provided with guide grooves formed at the time of the production of the disk. The guide grooves are used to keep the light beam for recording and reproduction in the center of a track. These guide grooves result in convex areas (lands) and concave areas (grooves) formed in spiral or concentric form on the disk. The disk using both the convex areas and concave areas as recording tracks (land tracks and groove tracks) can record twice as much information as a disk using either areas as recording tracks. This method is referred to as a land/groove recording method and is described in Japanese Patent Application Kokoku Publication No. 57859/1988.
A recording track is generally divided into sectors in the direction of the track, and in each of the sectors, identification information, such as a track number, and a sector number, is preformatted as physically formed convex and concave pits. The identification information is disposed in either of these methods: In one method, dedicated identification information for a land track or groove track is disposed; in another method, the information is disposed in a position shifted in a radial direction so that the information can be shared by a land track and a groove track adjacent to the land track, more specifically, along the boundary between a land track and a groove track.
The former method in which exclusive identification information is disposed in each track enables track-specific information to be included, making it easy to control the device. In the mastering of this type of disk, the pit width needs to be sufficiently narrower than the track pitch. It is therefore difficult to form desired pits with the same laser beam as that used for forming guide grooves. Thus, disk production process is complicated.
In the latter method of sharing identification information by a land track and a groove track adjacent to the land track, the device needs to judge which track is being reproduced because two tracks share the identification information, and the control is a little more complicated than that for the former exclusive disposition method. However, the same laser beam as that used for forming guide grooves can be used for pre-formatting the identification information in mastering, which can be done by deflecting the laser beam in a radial direction just by ¼ of the distance between the centers of the adjacent lands, by the use of a light deflection means. This type of optical disk and an optical information reproduction device using such optical disks are disclosed in Japanese Patent Application Kokai Publication No. 176404/1994.
An optical information reproduction device using an optical disk on which identification information is disposed in the latter method will next be described.
FIG. 7
shows the track format of the conventional optical disk.
FIG. 8
shows how the conventional identification information portion is disposed.
FIG. 9
is a block diagram showing the configuration of the optical information reproduction device for reproducing information from that type of optical disk.
In FIG.
7
and
FIG. 8
, reference numeral
1
denotes an identification information area in which identification information is preformatted; reference numeral
2
denotes a user information area In which user information is recorded by means of a variation in the local optical constant or physical shape; reference numeral
3
denotes a groove track; and reference numeral
4
denotes a land track. As shown in the figures, the groove track
3
or land track
4
is disposed in spiral form in the full circumferential extent, and the tracks are divided into sectors in the direction of the tracks. A sector includes, at the beginning, the identification information area
1
in which information for identifying the sector, such as the track number and sector number is recorded, and the identification information area
1
is followed by the user information area
2
for recording user data and the like. The identification information is shared by the land track
4
and the groove track
3
adjacent to the land track, and the displacement of the identification information from the track center of the land track
4
or groove track
3
is ¼ of the distance between adjacent land tracks
4
or of adjacent groove tracks
3
.
The configuration of the conventional optical information reproduction device will next be described with reference to FIG.
9
. In the figure, reference numeral
11
denotes an optical disk; reference numeral
12
denotes a spindle motor; reference numeral
13
denotes an optical head; reference numeral
14
denotes a first current-to-voltage (I/V) converting means; and reference numeral
15
denotes a second I/V converting means.
An adding means
16
adds the output of the first I/V converting means
14
and the output of the second I/V converting means
15
.
A sum signal detecting means
17
detects the information recorded on the disk by processing and then converts the output (a) of the adding means
16
into binary values.
A subtracting means
18
obtains a difference between the output of the first I/V converting means
14
and the output of the second I/V converting means
15
.
A polarity reversing means
19
reverses the polarity of the output waveform (b) of the subtracting means
18
according to the control signal from a controller
26
, which will be described later.
A difference signal detecting means
20
detects the information recorded on the disk by processing and then converts the output (d) of the polarity reversing means
19
into binary values.
A signal selecting means
21
selects the output (c) of the sum signal detecting means
17
or the output (e) of the difference signal detecting means
20
according to the control signal (f) from a control gate generation means
25
, which will be described later.
A clock generation means
22
generates the reproduction clock (CK) in synchronization with the output (g) of the signal selecting means
21
according to a control gate signal (RG) from the control gate generation means
25
.
A data demodulating means
23
judges whether the output (g) of the signal selecting means
21
is at level “1” or “0” at the timing of the reproduction clock from the reproduction clock generation means
22
and demodulates the data.
An address information reproduction means
24
reproduces an address after reproducing identification information by judging at the timing of the reproduction clock from the reproduction clock generation means
22
whether the output (g) of the signal selecting means
21
is at level “1” or “0”.
The control gate generation means
25
generates the control gate signal mentioned earlier, with reference to the timing of the address reproduction completion signal from the address information reproduction means
24
.
The controller
26
outputs a control signal to the polarity reversing means
19
according to the address information from the address information reproduction means
24
.
The optical head
13
comprises a laser diode (LD)
131
, a collimate lens
132
, a beam spli
Goto Kenji
Inoue Yoshiji
Shimamoto Masayoshi
Tsukamoto Manabu
Umeyama Takehiko
Chu Kim-Kwok
Hudspeth David
Mitsubishi Denki & Kabushiki Kaisha
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