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United States Patent m
Kulakowski et al.
[li] Patent Number:  Date of Patent:
 CHECKING MEDIA OPERATIONS AND RECORDING DURING OPTICAL RECORDING
 Inventors: John E. Kulakowski; Rodney J.
Means; David M. Oldham; Morovat
Tayefeh, all of Tucson, Ariz.
 Assignee: International Business Machines
Corporation, Armonk, N.Y.
 Appl. No.: 504,449
 Filed: Apr. 4,1990
Related U.S. Application Data
 Division of Ser. No. 239,863, Sep. 2, 1988, Pat. No. 4,941,139.
 Int. CI.* G11B 7/00
 U.S. CI 369/58
 Field of Search 369/54, 58, 59, 116,
 References Cited
U.S. PATENT DOCUMENTS
3,654,624 4/1972 Becker et al 346/138
3,657,707 4/1972 McFarland et al 350/296
4,005,259 1/1977 Kaneko 358/128'
4,145,758 3/1979 Drexler et al 365/200
pro Oth^h "tf ly59^
I CIRCUITS _ j !* I' *
4,225,873 9/1980 Winslow 369/54
4,494,226 1/1985 Hazel et al 369/45
4,570,251 2/1986 Yokota et al 369/100
4,611,318 9/1986 Winslow 369/54
4,631,713 12/1986 Romeas et al 369/54
4,648,085 3/1987 Shimonou 369/54
4,788,674 11/1988 Maeda et al 369/54
4,791,622 12/1988 Clay et al 369/59
4,809,253 2/1989 Baas et al 369/54
Primary Examiner—Donald McElheny, Jr.
Attorney, Agent, or Firm—H. F. Somermeyer
A magnetooptic recorder player provides for residual data checking and media defect checking. Media defect checking is effected by comparing the reflected light intensity of a modulated optical beam with the input data characteristics. A difference between the input data and the detected light intensities represents asperities in the record media. Residual data is checked by selectively gating MO detected signals during recording, which are intermediate the high intensity light beam pulses used for recording signals. Both the detected residual data and detected media asperities are counted for each addressable record storage area on the medium.
5 Claims, 2 Drawing Sheets
U.S. Patent May 21, 1991 Sheet 2 of 2 5,018,126
DATA 0 I 0 I 0 0 I 0 0 I 0 0 0 I 0 0 0 0 0 I 0 0
CHECKING MEDIA OPERATIONS AND
RECORDING DURING OPTICAL RECORDING
CROSS REFERENCE TO RELATED
This is a divisional application of Ser. No. 239,863, filed Sept. 2, 1988, now U.S. Pat. No. 4,941,139 issued July 10, 1990.
FIELD OF THE INVENTION
The present invention relates to optically recording information-bearing signals using non-ablative recording techniques.
BACKGROUND OF THE INVENTION
Several recording technologies have been used over the past years for recording data or other forms of information-bearing signals onto optical record members, such as rotatable disks. Ablative recording has been 20 used for the so-called write once/read many (WORM) recording systems. The information recorded on the record member is optically sensed by shining a light beam onto the recorded area and sensing the intensity modulation in the reflected light. For ablative systems, 25 the medium space between ablated areas provides for high reflection of light while the ablated areas reflect very little, if any, light into the sensing mechanism. The record member intensity modulates a read beam for enabling faithful recovery of the recorded information. 30 In a similar manner, so-called phase-change materials record information by changing the phase of the record member between crystalline and amorphous states. The surface reflectivity of the two states is different for intensity modulating a read light beam. Bipolymer sys- 35 terns can also be used, which reflect or transmit light of varying colors with varying intensities. Yet another system for optical recording uses magnetooptic technology. During the recording process, a magnetic steering field envelopes the area to be recorded. A laser beam 40 shines onto the recording area for heating a spot to be recorded above its Curie point temperature on the disk magnetooptic coating. Upon cooling, the heated area magnetically follows the magnetic steering field for recording the information represented by a modulated 45 write beam from a laser. For reading or tracking through the recorded area, the laser light beam has a reduced intensity such that the record area is not heated above the Curie point. Generally, such magnetooptic (hereinafter MO) record members require erasure to a 50 reference state before each recording operation, such as to a binary zero state (a so-called south pole being adjacent the recording and reading surface of the disk). Then, on a subsequent access to the record member, data can be recorded by selectively thermomagnetically 55 switching portions of the record member such that the north pole terminates at the reading and recording surface of the disk. The magnetic steering field is reversed during erasure.
An unfortunate characteristic of many MO record 60 members is that of media defects. Many of the defects can occur or be generated when the record member is first manufactured. Depending upon record member construction, additional defects can arise after the manufacture and even after data or other information-bear- 65 ing signals are recorded on an MO record member. Further, the size of the initial defects resulting from the manufacturing process may change in size. As a result,
powerful error detection and error correction code (ECC) systems are employed with the MO disk for accommodating such media defects. It is to be appreciated that the other media types are also subject to high defect rates The effective defect rates in MO are often higher than other magnetic recording media because of the increased density (smaller size signal recording areas) than commonly employed with magnetic recorders. Many magnetic media are manufactured which use expensive, high quality manufacturing processes. It is desired to avoid such additional expense in the optical recording area, yet provide for a high level of data integrity during recording and readback operations using optical media. Such integrities include checking the media for new or old defects, and checking for residual data, i.e., whether or not the record area has been faithful erased for faithful MO recording and readback. Such checks also test the operativeness of the data signal channel electronics.
DISCUSSION OF THE PRIOR ART
U.S. Pat. No. 4,494,226 shows an optical recorder of the ablative type employing a so-called three-beam head. One of the beams leads the record sensing and recording beams for detecting media defects. While a three-beam head certainly provides a faithful media integrity checking system, it is desired to avoid the constructional expense and complexity of providing a three-beam head in an optical recorder. Yet, it is desired to provide for media checking during recording in an optical recorder.
U.S. Pat. No. 4,570,251 shows another ablative optical recorder. This patent teaches sensing the reflected light from the laser beam when not recording pits, i.e., between ablating a record medium for recording binary ones on the disk. According to this patent, such sensing between ablatively recording pits detects the presence of prior ablated areas as reduced light reflection. Upon detecting an ablated area, recording is aborted. It is parenthetically pointed out that a greatly reduced reflected light intensity may also indicate a media defect. The patent apparently shows a desire to provide for residual data checking in those systems wherein second media light intensity modulates a read beam to recover recorded information-bearing signals from a record medium.
U.S. Pat. No. 4,648,085 shows reading ablatively recorded information during recording for verifying successful recording. Again, intensity modulation of the read beam by the record member is the basis for sensing a successful recording operation.
SUMMARY OF THE INVENTION
It is an object of the present invention to enhance the media and data integrity of optical recording apparatus, particularly for those optical recording systems employing recording technologies that yield recorded information by means other than intensity modulation of a read beam by the information indicia of the optical record disk.
In accordance with one aspect of the present invention, light used during a recording operation and reflected from the record member is intensity detected and then compared with the input signal. A non-compare indicates a media defect.
In a second aspect of the invention, which may be combined with the first aspect, during the intermediate