EP0376673A2
Expired / Lapsed
EP
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Optical recording element and optical data retrieval system for use with the same
Assignee: Sharp Corp
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Filing: 1989-12-27
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Granted: —
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Expires: 2009-12-27
Abstract
Abstract In the optical recording element of the invention, alignments of long thin pits inclined in various directions with respect to the track direction are formed on the tracks and information is recorded therein according to the different inclines of the pits, thereby performing higher-density and larger-volume recording without reducing the spacing between each pit and the track pitch. The invention also discloses an optical data retrieval system for use with the above optical recording element, which scans the pit alignments with a laser beam spot, detects the inclines of the pits by obtaining the distribution of the intensity of reflected light which is caused by light diffraction at the pits, and plays back information in accordance with the inclines. Therefore, not only can the substantially same structure as that of a standard type optical data retrieval system be applied to the invention without making any complicated change, but also cross-talk is less likely to be produced in the read out signals.
Inventors
- 👤 Hirotsugu Matoba
- 👤 Toshihisa Deguchi
- 👤 Shigeo Terashima
- 👤 Hideyoshi Yamaoka
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-05 11:27
CPC Classifications
G; G11; G11B; G11B7/00; G11B7/24; G11B7/2407; G11B7/24085; G11B7/004; G11B7/005; G11B7/007; G11B7/013
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
36 words
An optical recording element comprising, on the tracks thereof, alignments of long thin pits inclined in various directions with respect to the track direction, wherein information is recorded according to the different inclines of the pits.
Claim 2
Dependent Claim
36 words
An optical recording element comprising, on the tracks thereof, alignments of long thin pits inclined in various directions with respect to the track direction, wherein information is recorded according to the different inclines of the pits.
Claim 3
Dependent Claim
100 words
An optical data retrieval system for playing back information from an optical recording element having on the tracks thereof alignments of long thin pits inclined in various directions with respect to the track direction, the optical recording element being designed such that information is recorded therein according to the inclines of the pits, comprising: pit recognition retrieval means for playing back information in accordance with the inclines of the pits which are detected by obtaining the distribution of the intensity of reflected light from the pit alignments of the optical recording element to which a laser beam spot is irradiated.
Claim 4
Dependent Claim
100 words
An optical data retrieval system for playing back information from an optical recording element having on the tracks thereof alignments of long thin pits inclined in various directions with respect to the track direction, the optical recording element being designed such that information is recorded therein according to the inclines of the pits, comprising: pit recognition retrieval means for playing back information in accordance with the inclines of the pits which are detected by obtaining the distribution of the intensity of reflected light from the pit alignments of the optical recording element to which a laser beam spot is irradiated.
Claim 5
Dependent Claim
33 words
An optical recording element according to claim 1 or 2, wherein one round of track is divided into a plurality of sectors and the sector is treated as one unit in recording information.
Claim 6
Dependent Claim
72 words
An optical recording element according to claim 3, wherein the sector comprising a data area for storing 8 bytes of information and a servo area for storing information equivalent to 2 bytes, the latter information being used for the generation of a channel clock signal that is performed synchronously with the reading out of information stored in each sector and used for controlling each servo mechanism in the optical data retrieval system.
Claim 7
Dependent Claim
45 words
An optical recording element according to claim 4, wherein information is stored in the data area by four types of long thin pits, e.g. pits inclined at 0°, 90° and substantially 45° in a clockwise direction and counterclockwise direction with respect to the track direction.
Claim 8
Dependent Claim
82 words
An optical data retrieval system according to claim 4, further comprising an optical pick-up device which includes: a first photodetecting means for generating a controlsignal used for controlling the focus servo mechanism upon receipt of reflected light; a second photodetecting means for generating detection signals used for the playback of information; and an optical system for projecting a laser beam to produce a spot on the optical recording element and guiding reflected light therefrom to both the first and second photodetecting means.
Claim 9
Dependent Claim
38 words
An optical data retrieval system according to claim 6, wherein the second photodetecting means comprises a light receiving surface equally divided into a plurality of light receiving areas so that those light receiving areas are equal in size.
Claim 10
Dependent Claim
55 words
An optical data retrieval system according to claim 7, wherein the second photodetecting means has a rectangular light receiving surface equally divided into eight light receiving areas with parting lines, i.e., diagonal lines and lines each extending between the middle points of the opposite sides so that those light receiving areas are equal in size.
Claim 11
Dependent Claim
150 words
An optical data retrieval system according to claim 7, further comprising: a total signal generation circuit for generating a total signal by summing up the detection signals generated by the second photodetecting means which vary depending on the amount of light reflected at the pit alignment of the optical recording element; a tracking servo circuit for generating and releasing a control signal for controlling a tracking servo mechanism in the optical pick-up device; a focus servo circuit for generating and releasing a control signal for controlling the focus servo mechanism in the optical pick-up device; and a channel clock signal generation circuit for generating a channel clock signal synchronously with the playback of information stored in each sector of the optical recording element and releasing the channel clock signal to a pit recognition circuit functioning as the pit recognition retrieval means, the tracking servo circuit, and the focus servo circuit.
Claim 12
Dependent Claim
103 words
An optical recording element according to claim 4, wherein the servo area comprises: pits formed on the center of the track and used for the generation of a channel clock signal; a pair of pits which are used for controlling the tracking servo mechanism, and diagonally placed with the track therebetween, being equidistant from the center of the track in the radial direction of the optical disk so that a laser beam spot is not irradiated onto them at the same time; and a mirror section which is a flat area used for controlling the focus servo mechanism and has no pit therein.
Claim 13
Dependent Claim
69 words
An optical data retrieval system according to claim 9, wherein the tracking servo circuit releases a control signal to the optical pick-up device upon receipt of a channel clock signal from the channel clock signal generation circuit so that the levels of total signals respectively generated from the pair of pits formed in the servo area of the optical recording element are equal, thereby controlling the tracking servo mechanism.
Claim 14
Dependent Claim
70 words
An optical data retrieval system according to claim 9, wherein the focus servo circuit generates a control signal by astigmatism and releases it to the optical pick-up device, upon receipt of a channel clock signal from the channel clock signal generation circuit, so as to control the focus servo mechanism, the control signal being generated based on the output which corresponds to the mirror section from the first photodetecting means.
Claim 15
Dependent Claim
152 words
An optical data retrieval system according to claim 9, wherein the pit recognition circuit comprises: a plurality of adders for generating a sum signal from analog signals which vary in accordance with the respective amounts of light received at two adjacent light receiving areas out of a plurality of equally divided light receiving areas on the light receiving surface of the second photodetecting means; A/D converters as many as the adders, each of which is connected to the adder and converts the sum signal to a digital signal upon receipt of a channel clock signal from the channel clock signal generation circuit; a maximum value detection circuit for selecting a digital signal having a maximum value from the plurality of digital signals entered from the A/D converters; and a code data generation circuit for converting the selected signal having a maximum value to a code which is prefixed for every digital signal.
Claim 16
Dependent Claim
49 words
An optical data retrieval system according to claim 13, wherein the number of adders and the number of A/D converters are respectively equal to the number of types of the inclines of the long thin pits formed in the data area on the tracks of the optical recording element.
Claim 17
Dependent Claim
74 words
An optical recording element according to claim 5, wherein the four types of long thin pits having different inclines are represented by different codes, e.g. the pits inclined at 0° to the track direction are represented by "00"; the pits inclined at 90° to the same "11"; the pits inclined at 45° in a counterclockwise direction to the same "01"; and the pits inclined at 45° in a clockwise direction to the same "10".
Claim 18
Dependent Claim
105 words
An optical data retrieval system according to claim 13, wherein the maximum value detection circuit selects a digital signal as a signal having a maximum value, the digital signal being generated by converting a sum signal of the detection signals obtained from two adjacent light receiving areas where the ratio of (the total of the area where reflected light from the outside of the pit is received) to (the total of the area where reflected light from the pit is received) is the highest in the combinations of two adjacent light equally divided receiving areas on the light receiving surface of the second photodetecting means.
Claim 19
Dependent Claim
42 words
An optical data retrieval system according to claim 9, wherein the channel clock signal generation circuit generates a channel clock signal by PLL method from the total signal of the pits formed on the center of the track in the servo area.
Claim 20
Dependent Claim
43 words
An optical data retrieval system for retrieving data from an optical recording element according to claim 1, said system being adapted to read the recorded information by discriminating between said various directions of inclination of said pits with respect to said track direction.
References Cited (Backward Citations)
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