# US 5,710,749 A · Method and apparatus for determining an optical disc type

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- Number: US 5,710,749 A
- Document ID: US5710749A
- Status: Granted
- Kind: A
- Application number: 08/613,206
- Filed: 1996-03-06
- Granted: 1998-01-20
- Earliest claimed: 1995-03-10
- Assignees: Pioneer Electronic Corporation
- Inventors: Yoshiyuki Tsukai; Masanori Suzuki
- Web page: https://patentgrep.com/patent/US5710749A

## CPC

- G11B 19/06: by counting or timing of machine operations
- G11B 19/12: by sensing distinguishing features of {or on} records, e.g. diameter {end mark}
- G11B 7/0908: {for focusing only (G11B7/0925, G11B7/094, G11B7/0941, G11B7/0943, G11B7/0945, G11B7/0946, G11B7/0948 take precedence)}
- 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 method and apparatus for determining an optical disc type. A light beam is directed at an optical disc, and a focal point of the light beam moves in a focus direction with respect to the optical disc. An intensity of a reflection of the light beam from the optical disc is detected during the movement of the focal point of the light beam. A time interval between occurrences of a plurality of peaks of the detected intensity of the reflected light beam is detected, and the optical disc type is determined according to the detected time interval.

## Claims

### Claim 1

A method for determining an optical disc type, comprising the steps of:
directing a light beam at an optical disc;
moving a focal point of the light beam in a focus direction with respect to the optical disc;
detecting an intensity of a reflection of the light beam from the optical disc during the step of moving the focal point of the light beam;
detecting a time interval between occurrences of a plurality of peaks of the detected intensity of the reflected light beam; and
determining the optical disc type according to the detected time interval.

### Claim 2 (depends on 1)

The method of claim 1, wherein the detected time interval corresponds to a distance between a disc surface of the optical disc and a reflective surface of the optical disc.

### Claim 3 (depends on 1)

The method of claim 1, wherein the step of detecting the time interval is repeated a plurality of times to detect a plurality of time intervals, and wherein the step of determining the optical disc type determines the disc type according to an average of the plurality of time intervals.

### Claim 4 (depends on 1)

The method of claim 1, wherein the step of detecting the time interval is performed during a rotation of the optical disc.

### Claim 5 (depends on 3)

The method of claim 3, wherein the step of detecting the plurality of time intervals is performed during a rotation of the optical disc.

### Claim 6

An apparatus for determining an optical disc type, comprising:
means for directing a light beam at an optical disc;
means for moving a focal point of the light beam in a focus direction with respect to the optical disc;
means for detecting an intensity of a reflection of the light beam from the optical disc during the movement of the focal point of the light beam;
means for detecting a time interval between occurrences of a plurality of peaks of the detected intensity of the reflected light beam; and
means for determining the optical disc type according to the detected time interval.

### Claim 7 (depends on 6)

The apparatus of claim 6, wherein the detected time interval corresponds to a distance between a disc surface of the optical disc and a reflective surface of the optical disc.

### Claim 8 (depends on 6)

The apparatus of claim 6, wherein the means for detecting the time interval repeats the detection of the time interval a plurality of times to detect a plurality of time intervals, and wherein the determining means determining the disc type according to an average of the plurality of time intervals.

### Claim 9 (depends on 6)

The apparatus of claim 6, wherein the means for detecting the time interval detects the time interval during a rotation of the optical disc.

### Claim 10 (depends on 8)

The apparatus of claim 8, wherein the means for detecting the time interval detects the plurality of time intervals during a rotation of the optical disc.