# US 5,706,261 A · Optical disc device capable of quick search for a boundary between recorded and unrecorded areas

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- Number: US 5,706,261 A
- Document ID: US5706261A
- Status: Granted
- Kind: A
- Application number: 08/460,320
- Filed: 1995-06-02
- Granted: 1998-01-06
- Earliest claimed: 1994-06-02
- Assignees: Sony Corporation
- Inventors: Osamu Udagawa
- Web page: https://patentgrep.com/patent/US5706261A

## CPC

- G11B 27/24: by sensing features on the record carrier other than the transducing track {; sensing signals or marks recorded by another method than the main recording}
- G11B 7/08505: {Methods for track change, selection or preliminary positioning by moving the head}
- G11B 19/02: Control of operating function, e.g. switching from recording to reproducing
- G11B 27/105: {of operating discs}
- G11B 27/22: Means responsive to presence or absence of recorded information signals
- G11B 27/3063: {Subcodes}
- G11B 27/19: by using information detectable on the record carrier
- G11B 27/3027: {used signal is digitally coded}
- G11B 2220/218: Write-once discs
- G11B 2220/2545: CDs
- 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

An optical disc recording device in which RF signals reproduced from a write-once optical disc are detected during track jump for detecting the boundary between a recorded area and an unrecorded area on the write-once optical disc. This defines a roughly defined boundary between the recorded and unrecorded areas which may be searched quickly. A more strictly defined boundary between the recorded and unrecorded areas, may be searched quickly by subsequently employing a binary search method to the roughly detected boundary.

## Claims

### Claim 1

An optical disc recording device in which a light beam is radiated on an optical disc for recording data thereon, said optical disc having recorded and unrecorded areas, said optical disc recording device comprising:
a tracking actuator;
a circuit for outputting error signals to control movement of said tracking actuator and for outputting RF signals during track jump of said tracking actuator;
rough boundary detecting means for receiving said RF signals and for roughly detecting a boundary between said recorded and unrecorded areas; and fine boundary detecting means for finely detecting said boundary by a binary search method.

### Claim 2 (depends on 1)

The optical disc recording device according to claim 1, wherein said boundary between said recorded and unrecorded areas is roughly detected by said rough boundary detecting means and then finely detected by said fine boundary detecting means when the number of physical tracks in a search area of said optical disc is greater than a predetermined number and wherein said boundary is finely detected by said fine boundary detecting means without rough detection by said rough boundary detecting means when said number of said physical tracks in said search area of said optical disc is not greater than said predetermined number.

### Claim 3 (depends on 1)

The optical disc recording device as claimed in claim 1, wherein said optical disc is a write-once optical disc.

### Claim 4

An optical disc device for reading and recording data from and onto an optical disc including a number of physical tracks for storing said data thereon, said optical disc device comprising:
optical pickup means for reproducing signals by radiating a light beam onto said optical disc;
a tracking actuator for conveying said optical pickup means in a radial direction of said optical disc;
RF signal detection means for detecting whether RF signals are included in said signals reproduced by said optical pickup means;
a memory for storing addresses of a leading end and a trailing end of a search area of said optical disc, said search area having a recorded region and an unrecorded region therein; and
control means for controlling said optical pickup means, said tracking actuator and said RF signal detection means to search a boundary between said recorded region and said unrecorded region within said search area, wherein said control means searches said boundary via a binary search method where the number of said physical tracks in said search area is less than a preselected number and wherein said control means searches said boundary via detecting said RF signals and then via said binary search method where the number of said physical tracks in said search area is not less than said preselected number.

### Claim 5

An optical disc recording device in which a light beam is radiated on an optical disc for recording data thereon, said optical disc having recorded and unrecorded areas, said optical disc recording device comprising:
a tracking actuator;
a circuit for outputting error signals to control movement of said tracking actuator and for outputting RF signals during track jump of said tracking actuator;
rough boundary detecting means for receiving said RF signals and for roughly detecting a boundary between said recorded and unrecorded areas; and
fine boundary detecting means for finely detecting said boundary by a dichotomizing search method.

### Claim 6 (depends on 5)

The optical disc recording device according to claim 5, wherein said boundary between said recorded and unrecorded areas is roughly detected by said rough boundary detecting means and then finely detected by said fine boundary detecting means when the number of physical tracks in a search area of said optical disc is greater than a predetermined number and wherein said boundary is finely detected by said fine boundary detecting means without rough detection by said rough boundary detecting means when said number of said physical tracks in said search area of said optical disc is not greater than said predetermined number.