MXPA06000956A

MXPA06000956A - Hybrid recordable optical record carrier

Info

Publication number: MXPA06000956A
Application number: MXPA/A/2006/000956A
Authority: MX
Inventors: Vlutters Ruud; Cf Martens Hubert
Original assignee: Koninklijke Philips Electronics Nv; Martens Hubert C F; Vlutters Ruud
Priority date: 2003-07-25
Filing date: 2006-01-24
Publication date: 2006-12-13

Abstract

The present invention relates to a recordable optical record carrier which can be used to make a back-up of the full content of a SA-CD disc. The proposed record, carrier comprises:a first transparent substrate layer (1), a first semi-transparent recordable information layer (2) including an organic dye material having a high data storage capacity, a second transparent substrate layer (4), a second recordable information layer (5) including an organic dye material havingl,a lower data storage capacity than said first information layer (2), and a cover layer (6).

Description

For two-letter codes and other abbreviations, refer to the "Guidance Notes on Codes and Abbreviations" appearing at the beginning-ning ofeach regular issue of the PCT Gazette.

HYBRID RECORDABLE OPTICAL RECORDING CARRIER DESCRIPTION OF THE INVENTION The present invention relates to a recordable optical recording carrier comprising two different types of recordable information layers for recording information by means of a focused radiation beam. .: A hybrid optical ROM disc having two information layers that are compatible with different reading systems is described in US 6,434,107. A Super-Audiq-hybrid CD (SA-CD) consisting of two layers of information is described in the description of the CD Super-udio system, • part 1 physical description. The first information layer of •• such SÁ-CD is placed at a depth of 1.2 mm and contains conventional CD audio data. This layer of information can be read by existing CD players using a wavelength? of approximately 780 nm and an AN numerical aperture of 0.45. A second layer of information will •; • and placed at a depth of '0.6 mm. This second layer of semi-transparent information is a high density layer (HD) and contains the audio data in super audio quality ..

This high density information layer is read using DVD-like optics using a wavelength? of approximately 650 nm and an AM numerical aperture of 0.6. Currently, the media are available. ng Ref. 169257 recordable ones which can be used to make a backup copy of the complete content of such SA-CD. It is therefore an object of the present invention to provide such a recordable optical recording carrier. This object is achieved according to the present invention by a recordable optical recording carrier as claimed in claim 1 comprising: a first transparent substrate layer; - a first layer of semi-transparent recordable information including an organic dye material having a high data storage capacity, - a second layer of transparent substrate, - a second layer of recordable information including an organic dye material which it has a lower data storage capacity density than the first information layer, and - a cover layer. The present invention is based on the idea of combining a conventional CD-R information layer having a low data density (data storage capacity) with a semi-transparent DVD + R information layer having a high data density. . By this combination a recordable optical recording carrier is obtained which, in principle, is capable of storing a backup copy of the complete contents of a CD / DVD disc hybrid. Such hybrid optical disc can be recorded on a combined recorder (CD / DVD burner) with appropriate adaptations. Preferred embodiments of the invention are defined in the dependent claims. Preferably the first information layer is an information layer used as the LO layer on a double layer DVD + R disc. Layers suitable for use for the dual layer optical data storage means have been described in international patent applications PCT / IB03 / 00090 (PHNL 030043) and PCT / IB03 / 01377 (PHNL • 030310). All descriptions with respect to the LO layer provided in these documents are incorporated herein by reference. Preferred embodiments of the first information layer as described in these documents are defined in claims 3 to 6. According to a first preferred embodiment the first information layer has a first complex refractive index ñ? I = n? X - ik? xa a first length of oda? i, and a second complex refractive index ñ? 2 = n.?2 - ik? 2 at a second wavelength? 2, a thickness d, an optical reflection value R? at the first wavelength? i and an optical transmission value T2 at the second wavelength? 2, where the following conditions are met: T2 > 0.76, Rx _ 0.15, nx 2.0, kx < 0.3, k2 < 0.1 and d is in the range of ?? / 8? < d < 5? A / 8n ?,? I is the wavelength of a beam of radiation used to record the information in the first layer of information and? is the wavelength of a beam of radiation used to record the information in the second layer of information. To achieve a reflectivity R2 at the second wavelength? 2 used for recording and reading the . second information layer of at least 58% from the second information layer, the first information layer becomes highly transparent to the second wavelength? 2 used for recording and reading the second information layer. Preferably the transmission T2 of the first information layer is selected to be at least 76% at a second wavelength of? 2 = 780 nm, which preferably is used for recording in the second information layer. By a selection of the parameters as defined in claim 3, a sufficiently high transmission is obtained at the second wavelength, which preferably is 780 nm, and a sufficiently high reflectivity at the first wavelength, which preferably is 650 nm, and, at the same time, the information layer can be easily produced. The additional modalities of this idea are described in the international patent application PCT / IB03 / 01377 mentioned above, the additional embodiments are incorporated herein by reference. The preferred values of the thickness dRG of the slot portion are defined in claim 5. Preferably, a non-metallic reflective layer is provided adjacent to the first information layer, the additional reflective layer comprises a dielectric material, for example Si02, SiC, ZnS, ZNS-Si02 (80: 20) or a semiconductor material for example Si, and has a thickness dt in the range of < dt _ < 120 nm. In principle, it is possible to use a recordable information layer without dye as a first information layer. However, the use of dyes has the important advantage of a very high intrinsic transparency of the high density recording dye in the wavelength used for recording in the second information layer (CD-R). In a further embodiment the first and second substrate layers have a thickness in the range of 0.55 to 0.65 mm, particularly in the range of 0.57 to 0.63 mm, preferably approximately 0.6 mm. As already mentioned, an additional semitransparent reflective layer is provided in a further mode between the first information layer and the second substrate layer. This additional reflective layer can be either a dielectric (non-metallic) mirror layer made of for example Si02 or SiC, or a metal mirror layer, for example made of Ag. In addition, the semi-transparent reflective layer can be made from more than one layer, for example using mirror principles. dielectric for the precise tuning of the reflection in the wavelength used for recording / reading in the first layer of information (preferably? x = 650 nm) and the transmission used for recording / reading in the first layer of information (preferably? 2 = 780 nm). In addition to the aforementioned use for backing up the complete contents of an SA-CD, the recording bearer according to the present invention provides the possibility of distributing small volumes of SA-CDs since the efforts to produce SA-CDs Read only are totally high and expensive. Therefore, instead of SA-CD-ROM discs recordable recording carriers can be recorded with the same amount of information which is much easier and cheaper. In addition, the recording carriers according to the present invention can be used for authorship in the ROM disk production process. Before the start of a large-scale production of a disc, which has for example audio content, a first test disc is always made to verify if the disc works properly, for example to verify if the content is correct and if the disc It provides good reproduction etc. This rather It is an expensive procedure since it requires a complete production process that includes, among others, manufacture of negative to make discs, disc molding etc. It is much faster and cheaper to make a test recording of the content of the disc on a recordable recording carrier. The recording bearer according to the present invention can therefore be used in the process of authoring an SA-CD disk. The invention will now be explained in more detail with reference to the figures in which Figure 1 shows a schematic sketch of an optical recording carrier according to the invention, Figure 2 shows a schematic sketch of a portion of another embodiment of a recording carrier according to the invention, Figure 3 shows the optical constants of a typical tite used for the first information layer. Figure 4 shows the transmission of a first information layer with a dielectric mirror layer of Si02 at 780 nm, Figure 5 shows the transmission of the first information layer with a dielectric mirror layer of SiC at 780 nm and the figure 6 shows the transmission of the first layer of information with a metal mirror layer Ag to 780 nm. A schematic sketch of a first embodiment of a recording bearer according to the present invention is shown in figure 1. See from the side in which a recording / reading laser beam L having a wavelength? is incident, the recording carrier comprises the following layers: a first layer of transparent substrate, for example having a thickness of about 0.6 mm; - a first layer of recordable information at least semi-transparent 2 having a high data density and including an organic dye material as used for the information layers in DVD + R, for example having a thickness of about 80 nm; - an adhesive layer 3; - a second layer of transparent substrate 4, for example having a thickness of approximately 0.6 mm, - a second layer of information 5 including an organic dye material as used in the information layers of CD-R discs and having a low data density which is the first information layer 2, for example having a thickness of 150 nm; and - a cover layer 6. It should be noted that the information layers 2, 5 are shown as representative for recording blocks suitable ones which generally also include additional layers, such as mirror layers or dielectric reflectors which are not shown in Figure 1 for the sake of simplicity. The position of the second information layer 5 is determined by the total optical thickness of the two substrate layers 1 and 4 and the adhesive layer 3, ie the position of the second information layer 5 is determined by the optical depth: nx di + n4 d4 + n3 d3 where n the "real part of the complex refractive index ñ = ni ka a second wavelength? 2 (for example 780 nm) and d indicates the thickness.In a particular modality the position of the second layer of information 5 is at an optical depth of 1.86 ± 0.1, which results in an optical depth of the second information layer 5 which is identical to that in conventional CDs (CD substrate thickness 1.2 mm and substrate refractive index). CD 1.55) The optical thickness n * d is relevant at this point, for the first layer of information 2 this should be similar to CD: d * n = 1.2 mm * 1.55 The above calculations allow to correct the physical depth of the second information layer to the possibly different refractive indices of the spacer, adhesive and substrate layers. For reading and recording data in the first information layer 2, a laser beam L is used that has preferably a wavelength? i of approximately 650nm as used in DVD + R technology while reading and recording data in the second layer of 5. Is a laser beam L used that preferably has a second wavelength? of about 780 nm as used in CD-R technology. A reflection level of the information layers 2 and 5 at the respective wavelength should be at least 15% and 58% respectively. Achieving this for the second information layer 5 implies that the first information layer 2 must have a high transmission value T at the second wavelength 2 used for the recording / reading of data in the second information layer 5., that is to say at 780 nm. In a preferred embodiment the dye material, therefore, is selected such that the real part nS50 of the complex refractive index ñ650 is at least 2.0 and that the imaginary part k65o of the complex refractive index ñ65o is less than 0.3 at a first length of wave? 2 and that the imaginary part k78o of the complex refractive index ñ78o is less than 0.1 at the second wavelength? 2. Furthermore, it has been shown to be advantageous that the thickness of the first information recording layer 2 maintains: ??????????; _ d 3 ?? / 8n in the case of a semi-transparent non-metallic reflecting layer adjacent to the first recording layer or? i / 8n d 5 ?? / 8n in the case of a thin metallic semi-transparent reflecting layer adjacent to the first layer of information where? * is the wavelength used for recording / reading data from the first information layer 2, therefore, for example, being 650 nm. A portion of an embodiment of a recording bearer according to the invention is schematically shown in Figure 2. In this embodiment an at least semi-transparent reflective layer 7 is provided between the first information layer 2 and the second substrate layer. 4, the first information layer 2 and the reflective layer 7 form a recording block, which could possibly include additional layers (not shown) for the purpose of, for example transmission / reflection tuning, chemical stability, etc. It should be noted that the adhesive layer 3 is provided, but is not shown, but it can also be left out completely in a particular embodiment. In addition, the groove structure of the substrate layer 1 as well as the first information layer 2 and the additional reflective layer 7 are shown. As can be seen, the first substrate layer 1 has a guide groove having a depth g and the first information layer 2 has different thicknesses, a first thickness dRG in the groove portion which is greater than a thickness dRL in the portion between the slots. In contrast, the additional reflective layer 7 substantially has a constant thickness dt.

To obtain good signals at the wavelength? I used for reading / recording the first layer of information 2 a good selection of the slot depth is such that (?? / 650) * 50 nm < g < (?? / 650) * 180 nm, depending on the detailed block design. Furthermore, the preferred values for the thicknesses are such that they are maintained for dRG: wherein the thickness dRS of the first information layer meets the condition 145 nm < dRG • n < 245 nm. The thickness dRL in the portion between the grooves should be in the range dRG - 0.2 * g < dRL < _ dRG -0.5 * g, while the thickness dt of the reflecting layer 7 should be in the range 5 < dt < 120 nm. The particular values for the groove depth g are 50 nm < g < 180 nm. Practical exemplary values of a particular embodiment are: g = 80 nm, dt = 60 nm, dRL = 32 nm, dRG = 80 nm. Figure 3 shows the optical constants n, k of a typical dye material used for the first information recording block comprising the first information layer 2 and the reflecting layer 7. As can be seen, at the wavelength? = 780 nm used for recording / reading the second information layer, n is approximately 2.0 and k is approximately 0, while at the wavelength? = 655 nm used for recording / reading the first information layer 2, n is approximately 2.4 and k is approximately 0.1. Different materials can be used for the reflective layer 7. The transmission at a wavelength of 780 nm of the first information layer 2 with the additional reflective layer 7 for different materials, in particular for a dielectric reflecting layer of additional Si02, and Additional SiC dielectric reflective layer and an additional Ag metal reflective layer are shown in Figures 4, 5 and 6, respectively, depending on the reflective thickness. By using these diagrams an appropriate thickness can be selected so that the transmission is in the desired range. The present invention provides a recordable optical recording carrier which can be used to back up the entire contents. of a hybrid read-only SA-CD. In addition, small volumes of hybrid SA-CDs can be distributed through the use of recording carriers according to the present invention. Still further, such recording carriers can be used in the process of authoring hybrid read-only SA-CD discs. It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Claims

CLAIMS Having described the invention as above, the contents of the following claims are claimed as property:

1. Recordable optical recording carrier, characterized in that it comprises: - a first layer of transparent substrate, - a first layer of semi-transparent recordable information including an organic dye material having a high data storage capacity, - a second layer of transparent substrate, - a second layer of recordable information including an organic dye material having a lower data storage capacity than the first information layer, and - a cover layer.

2. The recording carrier according to claim 1, characterized in that the first information layer is an information layer used as the LO layer on a double layer DVD + R disc. Recording carrier according to claim 1 or 2, characterized in that the first information layer has a first complex refractive index = ?? - ik? l to a first length of oda? i, and a second complex refractive index ñ? 2 = n? 2 '- ik? 2 at a second wavelength? 2, a thickness d, an optical reflection value R at the first wavelength? x and an optical transmission value T2 at the second wavelength? 2, where the following conditions are met: T2 > 0.76, Rx _ > 0.15, na _ > 2.0, ki < 0.3, k2 < 0.1 and d is in the interval of? I / dn! < d < S? I / dni,? I is the wavelength of a beam of radiation used to record the information in the first layer of information and? 2 is the wavelength of a beam of radiation used to record the information in the second information layer. . Recording carrier according to claim 1, characterized in that the first substrate layer comprises a guide groove having a depth g, the guide groove is present on the side of the substrate layer adjacent to the first information layer and where the first information layer has a complex refractive index ñ = n - ik at a wavelength? of a radiation beam used to record the information, a thickness dRG in the slot portion and a thickness dRL in the portion between the slots, the depth of slot g is in the range (? / 650) * 50 nm < g < (? / 650) * 180 nm with? expressed in nm. 5. Recording carrier • according to claim 4, characterized in that the thickness dRG of the First layer of information meets the condition 145 nm < dRG • n < 245 nm. The recording carrier according to claim 3 or 4, characterized in that the first wavelength? I is approximately 650 'nm and the second wavelength? 2 is approximately 780 nm. The recording bearer according to claim 1, characterized in that the second information layer is an information layer as used on a CD-R disc. 8. Recording carrier according to claim 1, characterized in that the first and second substrate layers have a thickness in the range of 0.55 to 0.65 mm, in particular of substantially 0.6 mm. Recording carrier according to claim 1, characterized in that it additionally comprises an additional semi-transparent reflecting layer between the first information layer and the second substrate layer, in particular a dielectric mirror layer made of Si02 or SiC or a metal mirror layer made of Ag.