CA2344069A1 - Laser diode control in rewritable optical recording devices - Google Patents
Laser diode control in rewritable optical recording devices Download PDFInfo
- Publication number
- CA2344069A1 CA2344069A1 CA002344069A CA2344069A CA2344069A1 CA 2344069 A1 CA2344069 A1 CA 2344069A1 CA 002344069 A CA002344069 A CA 002344069A CA 2344069 A CA2344069 A CA 2344069A CA 2344069 A1 CA2344069 A1 CA 2344069A1
- Authority
- CA
- Canada
- Prior art keywords
- laser diode
- optical recording
- state
- writing
- states
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
- 230000003287 optical effect Effects 0.000 title claims description 12
- 238000005259 measurement Methods 0.000 abstract 1
- 239000012876 carrier material Substances 0.000 description 4
- 239000000463 material Substances 0.000 description 4
- 230000008018 melting Effects 0.000 description 2
- 238000002844 melting Methods 0.000 description 2
- 238000002425 crystallisation Methods 0.000 description 1
- 230000008025 crystallization Effects 0.000 description 1
- 239000000428 dust Substances 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
- 230000036962 time dependent Effects 0.000 description 1
Classifications
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
- G11B7/12—Heads, e.g. forming of the optical beam spot or modulation of the optical beam
- G11B7/125—Optical beam sources therefor, e.g. laser control circuitry specially adapted for optical storage devices; Modulators, e.g. means for controlling the size or intensity of optical spots or optical traces
- G11B7/126—Circuits, methods or arrangements for laser control or stabilisation
- G11B7/1263—Power control during transducing, e.g. by monitoring
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
- G11B7/12—Heads, e.g. forming of the optical beam spot or modulation of the optical beam
- G11B7/125—Optical beam sources therefor, e.g. laser control circuitry specially adapted for optical storage devices; Modulators, e.g. means for controlling the size or intensity of optical spots or optical traces
- G11B7/126—Circuits, methods or arrangements for laser control or stabilisation
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
- G11B7/004—Recording, reproducing or erasing methods; Read, write or erase circuits therefor
- G11B7/0045—Recording
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
- G11B7/004—Recording, reproducing or erasing methods; Read, write or erase circuits therefor
- G11B7/0045—Recording
- G11B7/00454—Recording involving phase-change effects
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
- G11B7/004—Recording, reproducing or erasing methods; Read, write or erase circuits therefor
- G11B7/006—Overwriting
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B2220/00—Record carriers by type
- G11B2220/20—Disc-shaped record carriers
- G11B2220/21—Disc-shaped record carriers characterised in that the disc is of read-only, rewritable, or recordable type
- G11B2220/215—Recordable discs
- G11B2220/216—Rewritable discs
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B2220/00—Record carriers by type
- G11B2220/20—Disc-shaped record carriers
- G11B2220/25—Disc-shaped record carriers characterised in that the disc is based on a specific recording technology
- G11B2220/2537—Optical discs
Landscapes
- Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Optical Recording Or Reproduction (AREA)
- Optical Head (AREA)
Abstract
The invention relates to an electronic device for optically recording onto rewritable media in which two different states are produced on the medium according to information content. According to the invention, the reflection of only one of the states is measured when writing the states, and the measurement for controlling the power of the laser diode is used also when writing the other state.
Description
PHN 17.554 12.02.2001 Laser diode controller in rewritable optical recording devices The invention relates to an optical recording device for recording on rewritable media with which two different state, depending on the information content are generated on the medium.
For writing optical media, for example, laser diodes are used to heat up the medium spot by spot. When a material layer of the optical medium is heated beyond its melting point, the material of this layer may be melted spot by spot. Without further supply of energy the information carrier material cools down fast and changes from the molten state to an amorphous state. With dosed energy supply, which keeps the information carrier material below the melting temperature for a certain period of time, but above the crystallization temperature inherent in this material, the information carrier material changes to a crystalline state. Since the reflecaion properties of the information carrier layer in the crystalline and in the amorphous state are widely different, the stored data may again be read by evaluation of the amount of reflected light.
Since during the writing operation the phase condition of the information carrier layer is determined by the energy applied to a certain area within a certain period of time, the control of the power produced by a laser diode as such is not sufficient, because soiling such as, for example, finger prints and dust particles on the surface of the optical storage medium, absorbs the energy applied to the material. If the energy applied by the laser diode is too small as a result of the soiling, the information carrier layer at this spot may go over to an amorphous state instead of a crystalline state, which is contrary to the projected effect. If the energy for the compensation for such soiling is selected to be higher, the energy applied at spots without soiling may become so high that the information carrier material changes over to a crystalline state undesirably. This would lead to the fact that the written information does not correspond to the information one would have liked to write.
For controlling the writing operation the written state is read preferably during the writing operation, to recognize disturbances of the writing operation and to compensate for them.
An optical recording device in which the amount of light used for the writing is controlled by changes in the reflected light is known, for example, from JP
5-292672. The PHN 17.554 2 12.02.2001 reflected light is buffered by means of the sample-and-hold circuit and compared to a reference value. The difference between measured value and reference value is used for controlling the amount of light radiated by the laser diode used for the writing.
It is an object of the invention to provide the control of the output power of the laser diode used for writing, so that it is also suitable for rewritable media.
This object is achieved in that during the writing of the states the reflection is measured of only one of the states and the measured value is used for controlling the power of the laser diode even when the other state is written.
Preferably, when a highly reflecting (= crystalline) state is written, the reflected amount of light is measured by means of a signal peak detector and compared to a reference value. In case of deviations, for example, as a result of soiling of the surface of the storage medium, the power of the la;~er diode is readjusted accordingly. The readjustment factor determined in this manner is ~ilso retained for writing a low-reflection (= amorphous) state. The invention here assumes that the soilings affecting the writing operation cover a large surface. An individual readjusl:ment for writing during a low-reflecting state is not necessary as a result. A channel coding ensures that each state repeats itself only a limited number of times anyhow. In this manner it is ensured that the highly reflecting states are not too far apart and the distances between highly reflecting states to be written are generally smaller than the extent of the soiling;s.
Preferably, the reflection is measured at the spots where a piece already in the highly reflecting state is overwritten with a highly reflecting state.
The invention will now be further described and explained on the basis of examples of embodiment shown in the sole Figure.
The example of embodiment shows an optical recording device comprising a control circuit 1 according to the invention for controlling the writing operation of a laser diode 2 on an optical medium 3. Thc: optical medium 3, for example, a CD-RW, is driven by a motor 4 shown diagrammatically. In a control circuit 5 is determined the respective laser power of the laser diode 2 necessary for achieving a certain write strategy and is predefined as a target value Px of the control circuit 1. By means of a photodiode (not shown) the storage medium is read out at the same position where it is written. The reading signal is applied to a peak value detector 6 arid generates a reading signal M. This reading signal is compared to a reference signal Mref and the difference signal is applied to an input of a multiplying stage 11 via a control neawork 13. The time-dependent control behavior of the control circuit 1 is determined by th~~ control network 13.
PHN 17.554 3 12.02.2001 Another input of the multiplying stage 11 is supplied with the nominal power Px. The output of the multiplying stage 11 is applied to a first input of a summing circuit 12.
To set the point of operation of the 1<~ser diode, the other input of the summing stage 12 is supplied with an offset voltage. When the amount of reflected light changes, the gain factor of the control circuit is adjusted accordingly so as to provide as constant a power as possible on the storage medium 3 when one or the other state is written.
For writing optical media, for example, laser diodes are used to heat up the medium spot by spot. When a material layer of the optical medium is heated beyond its melting point, the material of this layer may be melted spot by spot. Without further supply of energy the information carrier material cools down fast and changes from the molten state to an amorphous state. With dosed energy supply, which keeps the information carrier material below the melting temperature for a certain period of time, but above the crystallization temperature inherent in this material, the information carrier material changes to a crystalline state. Since the reflecaion properties of the information carrier layer in the crystalline and in the amorphous state are widely different, the stored data may again be read by evaluation of the amount of reflected light.
Since during the writing operation the phase condition of the information carrier layer is determined by the energy applied to a certain area within a certain period of time, the control of the power produced by a laser diode as such is not sufficient, because soiling such as, for example, finger prints and dust particles on the surface of the optical storage medium, absorbs the energy applied to the material. If the energy applied by the laser diode is too small as a result of the soiling, the information carrier layer at this spot may go over to an amorphous state instead of a crystalline state, which is contrary to the projected effect. If the energy for the compensation for such soiling is selected to be higher, the energy applied at spots without soiling may become so high that the information carrier material changes over to a crystalline state undesirably. This would lead to the fact that the written information does not correspond to the information one would have liked to write.
For controlling the writing operation the written state is read preferably during the writing operation, to recognize disturbances of the writing operation and to compensate for them.
An optical recording device in which the amount of light used for the writing is controlled by changes in the reflected light is known, for example, from JP
5-292672. The PHN 17.554 2 12.02.2001 reflected light is buffered by means of the sample-and-hold circuit and compared to a reference value. The difference between measured value and reference value is used for controlling the amount of light radiated by the laser diode used for the writing.
It is an object of the invention to provide the control of the output power of the laser diode used for writing, so that it is also suitable for rewritable media.
This object is achieved in that during the writing of the states the reflection is measured of only one of the states and the measured value is used for controlling the power of the laser diode even when the other state is written.
Preferably, when a highly reflecting (= crystalline) state is written, the reflected amount of light is measured by means of a signal peak detector and compared to a reference value. In case of deviations, for example, as a result of soiling of the surface of the storage medium, the power of the la;~er diode is readjusted accordingly. The readjustment factor determined in this manner is ~ilso retained for writing a low-reflection (= amorphous) state. The invention here assumes that the soilings affecting the writing operation cover a large surface. An individual readjusl:ment for writing during a low-reflecting state is not necessary as a result. A channel coding ensures that each state repeats itself only a limited number of times anyhow. In this manner it is ensured that the highly reflecting states are not too far apart and the distances between highly reflecting states to be written are generally smaller than the extent of the soiling;s.
Preferably, the reflection is measured at the spots where a piece already in the highly reflecting state is overwritten with a highly reflecting state.
The invention will now be further described and explained on the basis of examples of embodiment shown in the sole Figure.
The example of embodiment shows an optical recording device comprising a control circuit 1 according to the invention for controlling the writing operation of a laser diode 2 on an optical medium 3. Thc: optical medium 3, for example, a CD-RW, is driven by a motor 4 shown diagrammatically. In a control circuit 5 is determined the respective laser power of the laser diode 2 necessary for achieving a certain write strategy and is predefined as a target value Px of the control circuit 1. By means of a photodiode (not shown) the storage medium is read out at the same position where it is written. The reading signal is applied to a peak value detector 6 arid generates a reading signal M. This reading signal is compared to a reference signal Mref and the difference signal is applied to an input of a multiplying stage 11 via a control neawork 13. The time-dependent control behavior of the control circuit 1 is determined by th~~ control network 13.
PHN 17.554 3 12.02.2001 Another input of the multiplying stage 11 is supplied with the nominal power Px. The output of the multiplying stage 11 is applied to a first input of a summing circuit 12.
To set the point of operation of the 1<~ser diode, the other input of the summing stage 12 is supplied with an offset voltage. When the amount of reflected light changes, the gain factor of the control circuit is adjusted accordingly so as to provide as constant a power as possible on the storage medium 3 when one or the other state is written.
Claims (2)
1. An electronic optical recording device for optical recording on rewritable media, with which two different states depending on the information content are generated on the media, characterized in that during the writing of the states the reflection is measured of only one of the states and the measured value is used for controlling the power of the laser diode even if the other state is written.
2. An electronic device as claimed in claim 1, characterized in that the reflection is measured at the spots where a piece already in the highly reflecting state is overwritten with a highly reflecting state.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19932658.4 | 1999-07-15 | ||
| DE19932658A DE19932658A1 (en) | 1999-07-15 | 1999-07-15 | Laser diode control in rewritable optical recording devices |
| PCT/EP2000/006548 WO2001006499A1 (en) | 1999-07-15 | 2000-07-10 | Laser diode control in rewritable optical recording devices |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2344069A1 true CA2344069A1 (en) | 2001-01-25 |
Family
ID=7914580
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002344069A Abandoned CA2344069A1 (en) | 1999-07-15 | 2000-07-10 | Laser diode control in rewritable optical recording devices |
Country Status (10)
| Country | Link |
|---|---|
| EP (1) | EP1114416A1 (en) |
| JP (1) | JP2003505807A (en) |
| KR (1) | KR100752637B1 (en) |
| CN (1) | CN1154094C (en) |
| AU (1) | AU5984000A (en) |
| CA (1) | CA2344069A1 (en) |
| DE (1) | DE19932658A1 (en) |
| HU (1) | HUP0103926A3 (en) |
| PL (1) | PL346652A1 (en) |
| WO (1) | WO2001006499A1 (en) |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH05282672A (en) | 1990-05-18 | 1993-10-29 | Taiyo Yuden Co Ltd | Optical information recording device |
| GB9026774D0 (en) | 1990-12-10 | 1991-01-30 | Plasmon Data Systems Inc | Improving optical disk recording performance |
| US5184343A (en) | 1991-05-06 | 1993-02-02 | Johann Donald F | Compensation for dust on an optical disk by increasing laser writing power |
| JPH1040548A (en) * | 1996-07-26 | 1998-02-13 | Taiyo Yuden Co Ltd | Running opc method for optical disk and optical disk recording/reproducing apparatus |
| IL126369A (en) * | 1997-01-29 | 2002-11-10 | Koninkl Philips Electronics Nv | Method and device for recording and/or reproducing information |
-
1999
- 1999-07-15 DE DE19932658A patent/DE19932658A1/en not_active Withdrawn
-
2000
- 2000-07-10 WO PCT/EP2000/006548 patent/WO2001006499A1/en active Application Filing
- 2000-07-10 KR KR1020017003218A patent/KR100752637B1/en not_active IP Right Cessation
- 2000-07-10 PL PL00346652A patent/PL346652A1/en not_active Application Discontinuation
- 2000-07-10 CA CA002344069A patent/CA2344069A1/en not_active Abandoned
- 2000-07-10 AU AU59840/00A patent/AU5984000A/en not_active Abandoned
- 2000-07-10 CN CNB008014035A patent/CN1154094C/en not_active Expired - Fee Related
- 2000-07-10 HU HU0103926A patent/HUP0103926A3/en unknown
- 2000-07-10 EP EP00945904A patent/EP1114416A1/en not_active Ceased
- 2000-07-10 JP JP2001511674A patent/JP2003505807A/en not_active Withdrawn
Also Published As
| Publication number | Publication date |
|---|---|
| HUP0103926A2 (en) | 2002-03-28 |
| PL346652A1 (en) | 2002-02-25 |
| KR100752637B1 (en) | 2007-08-29 |
| KR20010075072A (en) | 2001-08-09 |
| HUP0103926A3 (en) | 2004-01-28 |
| CN1318193A (en) | 2001-10-17 |
| EP1114416A1 (en) | 2001-07-11 |
| AU5984000A (en) | 2001-02-05 |
| WO2001006499A1 (en) | 2001-01-25 |
| DE19932658A1 (en) | 2001-01-18 |
| CN1154094C (en) | 2004-06-16 |
| JP2003505807A (en) | 2003-02-12 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| FZDE | Discontinued |