MXPA99001733A - Disc-shaped information carrier provided with two portions having different read-out speeds - Google Patents

Abstract

A disc-shaped information carrier (1) with a substrate (3) and an information layer (5) which comprises optically readable elementary marks having a substantially uniform density. The information layer (5) comprises a first portion (11) suitable for being read out at a first read-out speed and a second portion (13) suitable for being read out at a second read-out speed higher than the first read-out speed. According to the invention, the second portion (13) of the information layer (5) is at a greater distance to a center (7) of the disc-shaped information carrier (1) than is the first portion (11) of the information layer (5). A range of rotational speeds which an optical read-out unit must have for a full and correct read-out of the information carrier (1) is reduced in this manner. In a special embodiment, the first portion (11) of the information layer (5) comprises a first version of an audio recording provided on the information layer (5) by the DSD transformation method, whereas the second portion (13) of the information layer (5) comprises a second version of this same audio recording provided on the information layer (5) by the PCM transformation method.

Description

CARRIER AND DISC FORM INFORMATION PROVIDED WITH TWO PORTIONS THAT HAVE DIFFERENT READING SPEEDS The invention relates to a disc-shaped information carrier with a substrate and an information layer, which comprises optically readable elementary labels with a substantially uniform density, the information layer is provided with a first portion comprising marks that must to be read at a first reading speed and a second portion comprising marks that must be read at a second reading speed greater than the first reading speed. An information carrier in the form of optically readable disk, known, is the compact disc (CD). The elementary marks of the CD information layer comprise small depressions, which are provided along the tracks in the information layer. The density of the marks is defined by an intersection present between the tracks and an interseparation present between the marks on a track. In addition to the standard CD, which may contain an audio program of more than one hour, a high density CD (HDCD) is known which has an information layer where the intersections present between the tracks, the intersections present between the marks. on a track, and the depressions themselves are substantially smaller than on a standard CD. The amount of information that the high-density CD can accommodate is thus substantially greater than the amount of information on the standard CD. that the available space of a high density CD is comparatively larger, the information layer of the high density CD can be provided with more than one portion, such as, for example, a first portion and a second portion, the information of the first portion is suitable, for example, to be read at a first reading speed and the information of the second portion is suitable, for example, to be read au. a second reading speed, which is substantially greater than the first reading speed. It can be understood that the term 'reading speed7' means the number of elementary marks that must be read per unit of time, also called bit rate in the case of a CD. The reading speed of each of the two portions is determined inter alia by the nature of the information present on each portion of the information layer. A disadvantage of a disc-shaped information carrier of the type mentioned above in the opening paragraph is that the information carrier can be read completely only by means of an optical reader unit, which has a comparatively wide range of rotational speeds . The object of the invention is to provide a disc-shaped information carrier of the type mentioned in the opening paragraph, which is capable of being read completely by means of a reading unit whose range of speeds rotations is as limited as possible. According to the invention, the disc-shaped information carrier for this purpose is characterized in that the second portion of the information layer is at a greater distance from the center of the disc-shaped information carrier than the first portion of the information layer. information layer. The rotational speed of the disk information carrier is determined by an arithmetic quotient of the reading speed at which the information is read, and the distance between the information that must be read and the center of the information carrier. of disk. As a result, the rotational speed of the information carrier is comparatively high during reading of the information present near the center of the information carrier and comparatively low during reading of the information present adjacent to the outer edge of the information carrier. Since the second portion of the information layer with a reading speed, comparatively high, is at a greater distance from the center of the information carrier than the first portion of the information layer having the first reading speed, comparatively low, according to the invention, a difference between the rotational speed during reading of the first portion and the rotational speed during the reading of the second portion is substantially reduced. As a result, the information carrier according to the invention can be read completely by means of a reading unit having a range of rotational speeds which is as limited as possible, so that the reading unit can be provided with a optimized control unit. A special embodiment of a disk information carrier according to the invention is characterized in that the first portion comprises a first version of an audio register and the second portion comprises a second version of the audio register different from the first version. . In this special modality, in which the space available on the information layer was used effectively, the two portions of the information layer comprise two different versions of one and the same audio record. A user of the information carrier, in this way, has the possibility, for example, of choosing between two different technical versions of the audio register, or the information carrier is suitable, for example, to be used in two different types of audio units. reading. An additional embodiment of a disc-shaped information carrier according to the invention is characterized in that the first version comprises a two-channel version of the audio register, while the second version is a six-channel version of the audio register. . The result of this is that the user of the disc-shaped information carrier has an interesting choice, for example, between a two-channel reproduction and a six-channel reproduction of the audio register. A further embodiment of a disc-shaped information carrier according to the invention is characterized in that the first portion and the second portion are provided on the information carrier by means of mutually different transformation methods. The first portion comprises, for example, information transformed by the DSD method (bitstream method), while the second portion comprises, for example, information transformed by the PCM method (pulse code modulation method). As a result, the information contained is suitable, for example, for use in two different types of reading units. A special embodiment of a disc-shaped information carrier according to the invention is characterized in that the first portion and the second portion are provided on the information carrier by mutually corresponding transformation methods. The invention will be explained in more detail below with reference to the drawings, in which Figure 1 shows schematically a disk information carrier according to the invention, Figure 2 shows a relationship between a rotational speed of a carrier of known information and a distance to the center of the information carrier, and Figure 3 shows a relationship between a rotational speed of the information carrier of Figure 1 and the distance to the center of the information carrier. The disc-shaped information carrier 1 according to the invention, shown schematically in the Figure 1 comprises a transparent disc-shaped substrate of synthetic resin 3, on which a comparatively thin reflective information layer 5 is provided, which layer comprises optically readable elementary marks. The information layer 5 is read by means of an optical beam from one side of the substrate 3 oriented towards the information layer 5. The elementary information marks 5 comprise small depressions, which are provided along substantially circular tracks in the information layer 5. The information layer 5 has a substantially uniform density, which is defined by an intersection present between consecutive tracks and an interseparation present between elementary marks on a track. The information layer 5 is readable by means of a reading unit suitable for this purpose, which unit rotates the information carrier 1 around an axis of rotation 9, which passes through a center 7 of the information carrier 1, an optical beam generated by the reading unit following the tracks of the information layer 5. As shown schematically in Figure 1, the information layer 5 comprises a first portion 11 of optically readable marks and a second portion 13 of optically readable marks. The first portion 11 of the information layer 5 is suitable to be read at a first reading speed, while the second portion 13 of the information layer 5 is suitable to be read at a second reading speed, which is substantially greater than the first reading speed. It should be understood that the term "reading speed" means the number of elementary marks that must be read per unit of time to achieve a correct reproduction of the information present on the information layer 5, this is subject Inter alia to the nature of the information to be read, As mentioned above, the information carrier 1 rotates around the axis of rotation 9 during the reading. The rotational speed? is determined by an arithmetic ratio of the reading speed and a distance r between the information to be read and the center 7 of the information carrier 1. As a result, the rotational speed? it is comparatively high during the reading of the information near the center of the CD (comparatively small value of r) and comparatively low during the reading of the information adjacent to the outer edge of the CD (value of r comparatively high), in the case of a standard CD that has a single reading speed, constant.

Figure 2 shows schematically a relationship between the rotational speed? of such a standard CD and the distance r to the center of the CD. The difference between the maximum rotational speed ÍOMAX and the minimum rotational speed OMIN is comparatively greater, so that it is only possible to read the standard CD completely by means of a reading unit having a sufficiently wide range of rotational speeds. As shown in Figure 1, the second portion 13 of the information layer 5 of the information carrier 1 according to the invention is at a greater distance from the center 7 of the information carrier 1 than the first portion 11 of the information carrier 1. Since the reading speed of the second portion 13 is substantially greater than the reading speed of the first portion 11, and the rotational speed of the information carrier 1 was determined by the arithmetic quotient of the reading speed and the distance between the information to be read and the center 7 of the information carrier 1, it follows that the difference between the rotational speed of the information carrier 1 during the readings of the first portion 11 and the rotational speed of the information carrier 1 during the reading of the second portion 13, is comparatively smaller. Figure 3 schematically shows a relationship between the rotational speed? ' of the information carrier 1 according to the invention and the distance r to the center 7 of the information carrier 1. The difference between the maximum rotational speed <; o 'ma and the minimum rotational speed?' mu is considerably smaller than the difference shown in Figure 2 between the maximum rotational speed OMAX and the minimum rotational speed «OMIN for the standard CD. As a result, the information carrier 1 can be read completely by means of a reading unit, which only has a limited range of rotation speeds.

The first portion 11 and the second portion 13 of the information layer 5 comprise, for example, a first version and a second version of one and the same audio register, respectively. The first version corresponds, for example, to a two-channel version of the audio register provided on the first portion 11 by the DSD transformation method (bit-stream method or 1-bit oversampled audio signal method), whereas the second version corresponds, for example, to a six-channel version of the audio register provided on the second portion 13, by a PCM transformation method (impulse code modulation method). A user of the information carrier 1, thus, has a choice, for example, between two versions of the audio record mentioned above, or the information carrier 1 can be read, for example, by means of two different types of units of reading, that is, by means of a reading unit suitable for reading information by the DSD transformation method and a reading unit suitable for reading information transformed by the PCM transformation method. In the disk information carrier 1, according to the invention as described above, the first portion 11 is suitable to be measured at a first reading speed, while the second portion 13 is suitable to be read at a second reading speed, which is substantially greater than the first reading speed. It should be noted that the first reading speed and the second reading speed, by themselves, do not need to be constant or have substantially constant values. In this way, for example, the first reading speed, and the second reading speed, each can have an average value, the values of the two reading speeds are allowed to deviate from the respective average values in, for example , when much 10%. It should also be noted that the disc-shaped information carrier according to the invention can alternatively be provided with more than two portions. In this way, an information carrier according to the invention can be provided, for example, with three portions, a first portion provided adjacent to the center of the information carrier having a comparatively low reading speed, a third portion provided adjacent to an outer edge of the information carrier having a comparatively higher reading speed, and a second portion provided between the first portion and the third portion, having a reading speed, which is greater than the reading rate of the first portion and less than the reading speed of the third portion.

The first portion 11 of the information carrier 1, according to the invention, as described above comprises a first version of the audio record, while the second portion 13 comprises the second version of the same audio record. It should be noted that the two portions of an information carrier according to the invention can also be assigned differently in, for example, an array in which the first portion comprises a version of a first audio record and the second portion a version of a second audio record. Finally, it should be noted that the two portions of the information carrier according to the invention can also be provided to the information carrier by one and the same transformation method such as, for example, the DSD transformation method or the transformation method. PCM

Claims (5)

CHAPTER CLAIMEDICATORÍO Having described the invention, it is considered as a novelty and, therefore, the content is claimed in the following:

1. A disc-shaped information carrier with a substrate and an information layer, which comprises optically readable elementary labels with a substantially uniform density, the information layer is provided with a first portion comprising marks that must be read to a first reading speed and a second portion comprising marks that must be read at a second reading speed, greater than the first reading speed, characterized in that the second portion of the information layer is at a greater distance from the center of the reading carrier. information in the form of a disk that the first portion of the information layer. The disk information carrier according to claim 1, characterized in that the first portion comprises a first version of an audio record, and the second portion comprises a second version of the audio record different from the first version. 3. The disc-shaped information carrier according to claim 2, characterized in that the first version comprises a two-channel version of the audio register, while the second version is a version of six audio recording channels. 4. The disc-shaped information carrier according to claim 1, 2 or 3, characterized in that the first portion and the second portion are provided on the information carrier by means of mutually different transformation methods. 5. The disc-shaped information carrier according to claim 1, 2 or 3, characterized in that the first portion and the second portion are provided on the information carrier by mutually corresponding transformation methods.