# US 5,706,263 A · Method and apparatus for high-density reproduction

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- Number: US 5,706,263 A
- Document ID: US5706263A
- Status: Granted
- Kind: A
- Application number: 08/364,984
- Filed: 1994-12-28
- Granted: 1998-01-06
- Earliest claimed: 1994-09-30
- Assignees: Samsung Electronics Co., Ltd.
- Inventors: Chul-woo Lee; Kyung-hwa Rim
- Web page: https://patentgrep.com/patent/US5706263A

## CPC

- G11B 7/133: Shape of individual detector elements
- B82Y 10/00: Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
- G11B 7/005: Reproducing (G11B7/0065 takes precedence)
- G11B 11/10543: {using optical beam of radiation}
- 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)
- B82Y: SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES

## Abstract

A method and apparatus for high-density reproduction of information recorded on an optical disk by increasing the optical resolution during reproduction. The apparatus focuses an optical beam reflected from the optical disk using a lens, and receives the focused reflected optical beam using a photodetector having an optical area whose width is smaller than the diameter of an optical spot formed thereon. As a result, jitter caused by interfering light, that is, light reflected from the circumference such as a recording portion adjacent to the optical disk, can be solved. Also, high-density reproduction can be performed by increasing the optical resolution during reproduction. The apparatus can be applied to an optical pickup for high-density recording.

## Claims

### Claim 1

A method for reproducing high density information recorded on an optical recording medium comprising:
irradiating an optical recording medium with an optical beam from a light source;
focusing the optical beam reflected from the optical medium using a lens to format least one optical spot, each optical spot having a diameter;
detecting the center portion of the at least one optical spot using at least one photodetector, each photodetector having a detecting area with a width substantially equal to half the diameter of each of the optical spots; and
generating an electrical signal from only the part of the optical spots overlying the respective detecting areas of the photodetectors.

### Claim 2 (depends on 1)

The method of claim 1 comprising dividing the optical beam focused by the lens into two orthogonally polarized components using an optical dividing element to form two optical spots.

### Claim 3 (depends on 1)

The method of claim 1 including detecting two optical spots using two photodetectors.

### Claim 4 (depends on 1)

The method of claim 1 including detecting two optical spots using two photodetectors and including, in generating the electrical signal, differentiating electrical signals generated by the two photodetectors.

### Claim 5

An apparatus for reproducing high-density information recorded on an optical recording medium comprising:
a lens for focusing an optical beam reflected from an optical recording media to format least one optical spot, each optical spot having a diameter; and
at least one photodetector, each photodetector having a detecting area centrally disposed with respect to the optical spot and having a width substantially equal to half the diameter of a corresponding optical spot incident on the photodetector, for generating an electrical signal only in response to the part of the corresponding optical spot incident on the respective detecting area.

### Claim 6 (depends on 5)

The apparatus of claim 5 including an optical dividing element for dividing the optical beam focused by the lens into two orthogonally polarized components to form two optical spots.

### Claim 7 (depends on 5)

The apparatus of claim 5 comprising two photodetectors.

### Claim 8 (depends on 5)

The apparatus of claim 5 wherein the lens has a focal length and the photodetector is located in a focal plane, one focal length from the lens.