# US 5,703,855 A · Optical disk apparatus and recording and reading method for an optical disk using the same

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- Number: US 5,703,855 A
- Document ID: US5703855A
- Status: Granted
- Kind: A
- Application number: 08/220,428
- Filed: 1994-03-30
- Granted: 1997-12-30
- Earliest claimed: 1993-04-06
- Assignees: Hitachi, Ltd.
- Inventors: Fumiyoshi Kirino; Tsuyoshi Toda; Horishi Ide; Hisataka Sugiyama; Atsushi Saito; Hiroyuki Tsuchinaga; Takeshi Maeda; Fumio Kugiya; Toshimitsu Kaku; Seiichi Mita; Kazuo Shigematsu; Yasuhide Ouchi
- Web page: https://patentgrep.com/patent/US5703855A

## CPC

- G11B 7/126: Circuits, methods or arrangements for laser control or stabilisation
- G11B 7/0045: Recording (G11B7/006, G11B7/0065 take precedence)
- G11B 7/0956: {to compensate for tilt, skew, warp or inclination of the disc, i.e. maintain the optical axis at right angles to the disc}
- G11B 11/1053: {to compensate for the magnetic domain drift or time shift}
- G11B 11/10595: {Control of operating function}
- G11B 20/1258: {where blocks are arranged within multiple radial zones, e.g. Zone Bit Recording or Constant Density Recording discs, MCAV discs, MCLV discs}
- G11B 20/182: {using test patterns}
- G11B: INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER (recording measured values in a way that does not require playback through a transducer G01D9/00; recording or playback apparatus using mechanically marked tape, e.g. punched paper tape, or using unit records, e.g. punched or magnetically marked cards G06K; transferring data from one type of record carrier to another G06K1/18; circuits for coupling output of reproducer to radio receiver H04B1/20; gramophone pick-ups or like acoustic electromechanical transducers or circuits therefor H04R)

## Abstract

A super high density optical disk apparatus is obtained by using an exchangeable recording medium having a recording capacity of at least 1.5 Gb/in.sup.2 in an optical recording and reading apparatus for recording or reading at least using a laser beam or by using one of an element which can record on a recording medium only once and another element which can record at least two times repeatedly as recording elements to be used.

## Claims

### Claim 1

A recording and reading method for an optical disk which is an optical information recording and reading method for recording and reading information by using at least an optical disk which is an optical recording medium which can be loaded or unloaded and an optical head for reading the information recorded on said optical disk, wherein the area where a special recording pattern of said optical disk is recorded is read when said optical disk is loaded, and a most suitable tap coefficient is obtained by an automatic equalizer consisting of a transversal filter of at least three taps, and an error signal value in proportion to the relative tilt between the optical disk and optical head is calculated on the basis of said tap coefficient, and the tilt of the optical head is mechanically adjusted so that said error signal value becomes almost zero (0), and the waveform distortion of a reading signal which is generated by a coma aberration generated by the tilt between the optical disk and optical head is removed.

### Claim 2

A recording and reading method for an optical disk which is an optical information recording and reading method for recording and reading information by using at least an optical disk which is an optical recording medium which can be loaded or unloaded and an optical head for reading the information recorded on said optical disk, wherein the area where a special recording pattern of said optical disk is recorded is read when said optical disk is loaded, and a most suitable tap coefficient is obtained by an automatic equalizer consisting of a transversal filter of at least three taps, and an error signal value in proportion to the relative tilt between the optical disk and optical head is calculated on the basis of said tap coefficient, and the tilt of the optical head is mechanically adjusted so that said error signal value becomes almost zero (0), and by finely adjusting said tap coefficient so as to remove the waveform distortion remaining in the reading signal by using said equalizer when recorded data is read, the distortion of waveform of a reading signal generated by a coma aberration generated by the tilt between the optical disk and optical head is removed.

### Claim 3

An optical disk apparatus which comprises at least an optical disk which is an optical recording medium which can be loaded or unloaded and an optical head for reading information recorded on said optical disk and includes signal processing means for removing the distortion of waveform of a reading signal from said optical head, means for obtaining information on the tilt between said optical disk and optical head in the peripheral direction or in the radial direction or in both directions from said signal processing means, and means for mechanically correcting the tilt between said optical disk and optical head-from said tilt information, said signal processing means being means for equalizing output signals from the optical head and including equalization means for calculating the tilt between the optical head and optical disk from the equalization characteristics optimized by using means for controlling the equalization characteristics adaptively for said equalization means.

### Claim 4 (depends on 3)

An optical disk apparatus according to claim 3, wherein said apparatus comprises a circuit for removing almost the tilt between said optical disk surface and optical head before recording or reading information by the optical head and removing the distortion of waveform due to the remaining tilt by the equalization means for calculating the tilt between the optical head and optical disk from the optimized equalization characteristics.

### Claim 5 (depends on 3)

An optical disk apparatus according to claim 3, wherein the equalization means for calculating the tilt between the optical head and optical disk from the optimized equalization characteristics comprises a circuit consisting of a transversal filter having at least three taps.

### Claim 6

An optical disk apparatus comprising an optical disk which can be loaded or unloaded, an optical head for forming a reading signal by detecting a laser beam thrown on said optical disk and reflected therefrom, a signal processing circuit for correcting waveform distortion of said reading signal from said optical head, a detecting circuit for detecting information on a tilt between said optical disk and optical head in a peripheral direction or in a radial direction or in both directions from said signal processing circuit, wherein the circuit property of said signal processing circuit is controlled by the output of said detecting circuit to correct the waveform distortion generated on said reading signal due to the tilt of said optical disk.

### Claim 7 (depends on 6)

An optical disk apparatus according to claim 6, wherein said optical disk apparatus comprises a control mechanism controlling the tilt of said optical disk by the output of said detecting circuit.