GB2319113A - Optical digital data storage medium - Google Patents
Optical digital data storage medium Download PDFInfo
- Publication number
- GB2319113A GB2319113A GB9622583A GB9622583A GB2319113A GB 2319113 A GB2319113 A GB 2319113A GB 9622583 A GB9622583 A GB 9622583A GB 9622583 A GB9622583 A GB 9622583A GB 2319113 A GB2319113 A GB 2319113A
- Authority
- GB
- United Kingdom
- Prior art keywords
- light
- data storage
- digital data
- optical digital
- storage device
- 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.)
- Withdrawn
Links
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
- G11B7/24—Record carriers characterised by shape, structure or physical properties, or by the selection of the material
-
- 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
- G11B7/005—Reproducing
Abstract
An optical digital data storage medium is constructed from light-attenuating material which suppresses the effects of scattered light and internal multiple reflections on the quality of the reproduced data. The material, through which a transducing beam travels, has a light transmission factor of 80% or less for the wavelength of the light insert to read the data.
Description
Optical Digital Data Storaae Device Medium
This invention reiates to an optical digital data storage device medium.
Most optical digital data storage devices are generically referred to as compact disks (CDs). Variants of these storage devices include CD-ROMs (CD Read-Only-Memory), CD-WORMs (CD Write-Once-Read
Many) and MultipleRead-Write Optical Disks. While this text refers to any such disk type optical digital storage media the principle described and the scope of this invention applies equally well to other media formats involving the replay of stored digital code using reflected light beams.
Information, here described as data, is stored in these devices as a digitally encoded pattern of markings which can be created by a variety of means and which may be permanent or erasable and rewritable. As the disk is rotated these markings intersect a light beam, usually from a solid state laser, which is directed at the disk's playing surface. The specularly reflected light beam (or the transmitted light beam in the case of a device working with transmitted light) is modulated by the pattern of markings intersecting the light beam, thereby forming a "primary signal" which is a reproduction of the stored digital code (the data).
Compact audio disks are the most common form of digital data storage device in use at the time of writing so the following illustration relates to these. Audio CDs are mass-produced by the injection moulding of rigid plastic replicas of a master disk called a stamper. The type of plastic used is normally a highly transparent polycarbonate with low birefringence qualities. The active surface of the plastic disc (ie the surface containing the digital code) is metallised to create a reflective surface which is then protected from damage by means of a thin coating or encapsulation of a durable material. This material is often selected for its ability to accept printing ink, and forms the non-playing surface of the disk. The light beam used to read the digital code is directed at the playing surface through the polycarbonate disk.
When the light beam travels through such a medium and strikes interfaces, surface imperfections or embedded impurities there is a possibility of light scattering and internal reflection. Such scattered light and light undergoing multiple internal reflections can eventually return to the signal detector and create a "secondary signal" which can degrade the accuracy of reproduction of the stored data, a process which is referred to here as distortion of the data. In digital audio replay this manifests itself as a loss of depth of the stereo image, harshness of mid and high frequencies, "boominess" of bass notes and a masking of fine detail in the reproduced sound.
This invention involves a means of reducing the contribution of scattered and internally reflected light to the replayed signal. This is done by making the medium from which the storage device is manufactured and through which the light beam travels an attenuating medium for the wavelength or wavelengths of light used for data retrieval. All media used for the manufacture of CDs attenuate light to some degree, but presently the media used are selected for a high degree of transparency (a light transmission factor T of around 90% [DIN 5036] being typical). Digital encoding and replay is relatively insensitive to the amplitude of the signal. Therefore, providing adequate primary signal can be returned to the detection system for accurate reproduction of the stored code, it is possible to use a medium with lower transparency.
The path within the medium travelled by the light beam which generates the "primary signal" is approximately twice the CD medium's thickness in the case of reflection replay, or is equal to the medium's thickness in transmission replay. The path within the medium travelled by the scattered light and light undergoing multiple internal reflections, which generates the "secondary signal", is greater than this. Since the degree of attenuation of the light is dependent on the distance which the light travels within the medium, the "secondary signal" is attenuated more than the "primary signal". This suppression of the unwanted secondary signal results in an improvement in the quality of the reproduced data.
Claims (9)
1. An optical digital data storage device constructed using a light-attenuating medium having a light transmission factor for the wavelength or wavelengths of light used by the replay system of 80% or less.
2. An optical digital data storage device constructed using a light-attenuating medium having a light transmission factor for the wavelength or wavelengths of light used by the replay system of 70% or less.
3. An optical digital data storage device constructed using a light-attenuating medium having a light transmission factor for the wavelength or wavelengths of light used by the replay system of 60% or less.
4. An optical digital data storage device constructed using a light-attenuating medium having a light transmission factor for the wavelength or wavelengths of light used by the replay system of 50% or less.
5. An optical digital data storage device constructed using a light-attenuating medium having a light transmission factor for the wavelength or wavelengths of light used by the replay system of 40% or less.
6. An optical digital data storage device constructed using a light-attenuating medium having a light transmission factor for the wavelength or wavelengths of light used by the replay system of 30% or less.
7. An optical digital data storage device constructed using a light-attenuating medium having a light transmission factor for the wavelength or wavelengths of light used by the replay system of 20% or less.
8. An optical digital data storage device constructed using a light-attenuating medium having a light transmission factor for the wavelength or wavelengths of light used by the replay system of 10% or less.
9. An optical digital data storage device constructed using a coloured medium which through its ability to attenuate the light used by the replay system as defined in any of claims 1 to 8 gives rise to an improvement in replay quality.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9622583A GB2319113A (en) | 1996-10-30 | 1996-10-30 | Optical digital data storage medium |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9622583A GB2319113A (en) | 1996-10-30 | 1996-10-30 | Optical digital data storage medium |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB9622583D0 GB9622583D0 (en) | 1997-01-08 |
| GB2319113A true GB2319113A (en) | 1998-05-13 |
Family
ID=10802163
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB9622583A Withdrawn GB2319113A (en) | 1996-10-30 | 1996-10-30 | Optical digital data storage medium |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2319113A (en) |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2005457A (en) * | 1977-09-29 | 1979-04-19 | Philips Nv | Optically written information recording element |
| US4548889A (en) * | 1982-01-12 | 1985-10-22 | Dainippon Ink And Chemicals, Inc. | Optical recording medium |
| US5190800A (en) * | 1991-01-17 | 1993-03-02 | Pioneer Electronic Corporation | Optical recording medium |
| EP0585710A2 (en) * | 1992-08-19 | 1994-03-09 | Diafoil Hoechst Co., Ltd | Multilayered polyester base film for optical tape |
-
1996
- 1996-10-30 GB GB9622583A patent/GB2319113A/en not_active Withdrawn
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2005457A (en) * | 1977-09-29 | 1979-04-19 | Philips Nv | Optically written information recording element |
| US4548889A (en) * | 1982-01-12 | 1985-10-22 | Dainippon Ink And Chemicals, Inc. | Optical recording medium |
| US5190800A (en) * | 1991-01-17 | 1993-03-02 | Pioneer Electronic Corporation | Optical recording medium |
| EP0585710A2 (en) * | 1992-08-19 | 1994-03-09 | Diafoil Hoechst Co., Ltd | Multilayered polyester base film for optical tape |
Also Published As
| Publication number | Publication date |
|---|---|
| GB9622583D0 (en) | 1997-01-08 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| EP0414380B1 (en) | Optical recording and reproducing apparatus and adaptor for use with said apparatus | |
| JP3210549B2 (en) | Optical information recording medium | |
| KR100432339B1 (en) | Multilayer optical disk | |
| US5134604A (en) | Combination optical data medium with multiple data surfaces and cassette therefor | |
| EP0855701B1 (en) | Optical pickup compatible with recordable compact disk and digital video disk using plane parallel plates | |
| EP0434230B1 (en) | Optical recording medium and method of recording and reproducing information thereon | |
| WO1983001532A1 (en) | Preformatted optical media for use in an optical memory system | |
| KR980004773A (en) | Optical recording medium and optical pickup device checking method | |
| EP1569209B1 (en) | Data read/write device for holographic WORM media and method thereof | |
| JPH01258244A (en) | Information recording medium, optical information recording method and optical information reproducing method | |
| CN1209758C (en) | Object lens for compatible optical recording media with different thicknesses | |
| US6400677B2 (en) | High recording density optical disc | |
| US5892748A (en) | Optical pickup for reading or recording information on a recording surface | |
| GB2319113A (en) | Optical digital data storage medium | |
| JPH0316025A (en) | Reference optical disk | |
| JP3108671B2 (en) | Magneto-optical memory device | |
| JP2863431B2 (en) | Magneto-optical recording / reproducing device | |
| KR100408278B1 (en) | Optical recording medium on which visible watermark is recorded | |
| TW470944B (en) | Optical recording medium and manufacturing method therefor | |
| AU4260697A (en) | Dual data recorded compact disc | |
| JPH09265667A (en) | Optical disk | |
| KR100255308B1 (en) | Optical pick-up | |
| KR100358099B1 (en) | Optical Pick-up Device | |
| KR970067151A (en) | Recording medium playback apparatus and recording medium playback method | |
| JPH03290835A (en) | Optical recording medium disk |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |