Device for scanning a disc-shaped information carrier with controlled changes in angular and linear velocities

Abstract

For scanning a disc-shaped information carrier at a high average information rate with minimum access time, the angular velocity is decreased substantially as the radial distance to the scan location increases, while at the same time the linear velocity of track scanning increases substantially. The track may be divided into zones which are scanned with constant angular velocity. With respect to the inner tracks of at least two adjacent zones, or the innermost and the outermost tracks, the angular velocity decreases less than inversely with increase of radial distance, while the linear velocity increases less than proportionally with increase of radial distance.

1. A device for scanning an information track on a disc-shaped information carrier, comprising:
 scanning means for scanning a location on the information track,  
 drive means for causing relative rotation between the location and the information carrier, at an angular velocity about a point of rotation, the location thereby having a linear velocity of relative movement along the track,  
 means for varying a distance (r) between said location and the point of rotation, and  
 control means for controlling the drive means,  
 characterized in that said control means is arranged to control the drive means so as to cause the relative angular velocity to decrease substantially with increasing distance (r), and to cause the linear velocity to increase substantially with increasing distance (r).  
 
     
     
       2. A device as claimed in  claim 1 , characterized in that said drive means rotates said information carrier about an axis through said point of rotation, said scanning means includes a scanning head, and said means for varying moves said scanning head radially with respect to said axis. 
     
     
       3. A device as claimed in  claim 1 , characterized in that said control means are arranged to change said relative rotation such that a first period of time, required to allow said location to be moved to another part of the information track by a rapid variation of said distance, is equal to or longer than a second period of time required to change the relative rotation such that the linear velocity resulting from the changed relative rotation and said rapid variation corresponds to a linear velocity at which the information can be processed. 
     
     
       4. A device as claimed in  claim 1 , characterized in that said control means are arranged to change said relative rotation such that for location between a first distance corresponding to the outermost track and a second distance, the linear velocity is substantially equal to a maximum velocity; and for locations between the second distance and a third distance corresponding to the innermost track, the linear velocity is less than the maximum velocity. 
     
     
       5. A device as claimed in  claim 4 , characterized in that
 said control means are arranged to change said relative rotation such that a first period of time, required to allow said location to be moved to another part of the information track by a rapid variation of said distance, is equal to or longer than a second period of time required to change the relative rotation such that the linear velocity resulting from the changed relative rotation and said rapid variation corresponds to a linear velocity at which the information can be processed, and  
 the second distance is the smallest distance for which the first and second periods of time are substantially equal.  
 
     
     
       6. A device as claimed in  claim 5 , characterized in that the control means are arranged to set the linear velocity such that the first and second periods of time are substantially equal for locations between the second distance and the third distance. 
     
     
       7. A device as claimed in  claim 4 , characterized in that
 said control means are arranged to change said relative rotation such that a first period of time, required to allow said location to be moved to another part of the information track by a rapid variation of said distance, is equal to or longer than a second period of time required to change the relative rotation such that the linear velocity resulting from the changed relative rotation and said rapid variation corresponds to a linear velocity at which the information can be processed, and  
 said control means are arranged to set the linear velocity such that the first and second periods of time are substantially equal for locations between the second distance and the third distance.  
 
     
     
       8. A device for scanning an information track on a disc-shaped information carrier, where said track includes an innermost track, an outermost track, and a multiplicity of tracks therebetween, comprising:
 scanning means for scanning a location on the information track,  
 drive means for causing relative rotation between the location and the information carrier, at an angular velocity about a point of rotation, the location thereby having a linear velocity of relative movement along the track,  
 means for varying a distance (r) between said location and the point of rotation, and  
 control means for controlling the drive means,  
 characterized in that said control means is arranged to control the drive means so as to cause the relative angular velocity to decrease substantially, but less than inversely with the increase of distance (r), as said location is moved from said increment track to said outermost track; and to cause the linear velocity to increase substantially, but less than proportionally with the increase of distance (r), at said location is moved from said innermost track to said outermost track.  
 
     
     
       9. A device as claimed in  claim 8 , characterized in that said drive means rotates said information carrier about an axis through said point of rotation, said scanning means includes a scanning head, sand said means for varying moves said scanning head radially with respect to said axis. 
     
     
       10. A device as claimed in  claim 8 , characterized in that said drive means is a means for rotating said information carrier about said point of rotation, and
 the control means sets the angular velocity in dependence on the distance (r).  
 
     
     
       11. A device as claimed in  claim 8 , characterized in that the control means is arranged to cause the drive means to scan with a constant linear velocity while information is being recorded. 
     
     
       12. A device as claimed in  claim 8 , characterized in that the control means is arranged to derive the distance (r) from information in the information track. 
     
     
       13. A device as claimed in  claim 8 , characterized in that said control means are arranged to change said relative rotation such that a first period of time, required to allow said location to be moved to another part of the information track by a rapid variation of said distance, is equal to or longer than a second period of time required to change the relative rotation such that the linear velocity resulting from the changed relative rotation and said rapid variation corresponds to a linear velocity at which the information can be processed. 
     
     
       14. A device as claimed in  claim 8 , characterized in that the control means is arranged to set the linear velocity in dependence on the density (r). 
     
     
       15. A device as claimed in  claim 8 , characterized in that an operational area of the distance (r) is subdivided into a number of zones each having an inner track,
 said drive means is a means for rotating said information carrier about said point of rotation, and  
 the control means sets the linear velocity at a constant velocity determined by the zone, such that for at least one zone the angular velocity decreases less than inversely with increase of distance between the inner tracks on the at least one zone and an adjacent zone.  
 
     
     
       16. A device as claimed in  claim 8 , characterized in that said control means are arranged to change said relative rotation such that for locations between a first distance corresponding to the outermost track and a second distance, the linear velocity is substantially equal to a maximum velocity; and for locations between the second distance and a third distance corresponding to the innermost track, the linear velocity is less than the maximum velocity. 
     
     
       17. A device as claimed in  claim 16 , characterized in that said control means are arranged to change said relative rotation such that a first period of time, required to allow said location to be moved to another part of the information track by a rapid variation of said distance, is equal to or longer than a second period of time required to change the relative rotation such that the linear velocity resulting from the changed relative rotation and said rapid variation corresponding to a linear velocity at which the information can be processed, and
 the second distance is the smallest distance for which the first and second periods of time are substantially equal.  
 
     
     
       18. A device as claimed in  claim 17 , characterized in that the control means are arranged to set the linear velocity such that the first and second periods of time are substantially equal for locations between the second distance and the third distance. 
     
     
       19. A device as claimed in  claim 16 , characterized in that the control means are arranged to set the linear velocity such that the first and second periods of time are substantially equal for locations between the second distance and the third distance. 
     
     
       20. A device for scanning a plurality of information tracks recorded on a disc- shaped information carrier, comprising:      a scan head that generates a scanning beam that scans the information tracks;        a scan head drive that moves the scan head in a radial direction relative to the information tracks, to thereby vary a radial distance  ( r )  between the scanning beam and a rotational axis; and,        a carrier drive that imparts rotational movement of the carrier about the rotational axis at an angular velocity that decreases as the radial distance  ( r )  increases, wherein the angular velocity is not inversely proportional to the radial distance  ( r ).    
     
     
       21. The device as set forth in  claim 20 , wherein a linear velocity of the scanning beam relative to an information track being scanned increases as the radial distance ( r )  increases, wherein the linear velocity is not proportional to the radial distance  ( r ).  
     
     
       22. The device as set forth in  claim 20 , wherein the information tracks comprise respective convolutions of a spiral track.  
     
     
       23. The device as set forth in  claim 20 , wherein the disc- shaped information carrier comprises an optical disc.    
     
     
       24. The device as set forth in  claim 20 , wherein the disc- shaped information carrier comprises a magneto - optical disc.    
     
     
       25. The device as set forth in  claim 20 , wherein the scanning beam comprises a laser beam.  
     
     
       26. The device as set forth in  claim 20 , wherein the scan head comprises a read/write head.  
     
     
       27. The device as set forth in  claim 20 , wherein the scan head comprises an optical head.  
     
     
       28. A device for scanning a plurality of information tracks recorded on a disc- shaped information carrier, comprising:      a scan head that generates a scanning beam that scans the information tracks;        a carrier drive that imparts rotational movement of the carrier about a rotational axis at an angular velocity that decreases as a radial distance  ( r )  between the scanning beam and the rotational axis increases, wherein the angular velocity is not inversely proportional to the radial distance  ( r ) ; and,        a scan head drive that moves the scan head in a radial direction relative to the information tracks, to thereby vary the radial distance  ( r )  between the scanning beam and the rotational axis, wherein a linear velocity of the scanning beam relative to an information track being scanned increases as the radial distance  ( r )  increases, and wherein further, the linear velocity is not proportional to the radial distance  ( r ).    
     
     
       29. The device as set forth in  claim 28 , wherein the information tracks comprise respective convolutions of a spiral track.  
     
     
       30. The device as set forth in  claim 28 , wherein the disc- shaped information carrier comprises an optical disc.    
     
     
       31. The device as set forth in  claim 28 , wherein the disc- shaped information carrier comprises a magneto - optical disc.    
     
     
       32. The device as set forth in  claim 28 , wherein the scanning beam comprises a laser beam.  
     
     
       33. The device as set forth in  claim 28 , wherein the scan head comprises a read/write head.  
     
     
       34. The device as set forth in  claim 28 , wherein the scan head comprises an optical head.  
     
     
       35. A device for scanning a plurality of information tracks recorded on a disc- shaped information carrier, comprising:      a scan head that generates a scanning beam that scans the information tracks;        a carrier drive that imparts rotational movement of the carrier about a rotational axis; and,        a scan head drive that moves the scan head in a radial direction relative to the information tracks, so thereby vary a radial distance  ( r )  between the scanning beam and the rotational axis, wherein a linear velocity of the scanning beam relative to an information track being scanned increases as the radial distance  ( r )  increases, and wherein further, the linear velocity is not proportional to the radial distance  ( r ).    
     
     
       36. The device as set forth in  claim 35 , wherein the information tracks comprise respective convolutions of a spiral track.  
     
     
       37. The device as set forth in  claim 35 , wherein the disc- shaped information carrier comprises an optical disc.    
     
     
       38. The device as set forth in  claim 35 , wherein the disc- shaped information carrier comprises a magneto - optical disc.    
     
     
       39. The device as set forth in  claim 35 , wherein the scanning beam comprises a laser beam.  
     
     
       40. The device as set forth in  claim 35 , wherein the scan head comprises a read/write head.  
     
     
       41. The device as set forth in  claim 35 , wherein the scan head comprises an optical head.  
     
     
       42. A device for scanning a plurality of information tracks recorded on a disc- shaped information carrier, comprising:      a scan head that generates a scanning beam that scans the information tracks;        a drive system that imparts relative radial movement between the scanning beam and the carrier, to thereby vary a radial distance  ( r )  between the scanning beam and a central axis of the carrier; and,        a servo controller that controls the drive system to increase a linear velocity of the scanning beam relative to an information track being scanned as the radial distance  ( r )  increases, wherein the linear velocity is not proportional to the radial distance  ( r ).    
     
     
       43. The device as set forth in  claim 42 , wherein the information tracks comprise respective convolutions of a spiral track.  
     
     
       44. The device as set forth in  claim 42 , wherein the disc- shaped information carrier comprises an optical disc.    
     
     
       45. The device as set forth in  claim 42 , wherein the disc- shaped information carrier comprises a magneto - optical disc.    
     
     
       46. The device as set forth in  claim 42 , wherein the scanning beam comprises a laser beam.  
     
     
       47. The device as set forth in  claim 42 , wherein the scan head comprises a read/write head.  
     
     
       48. The device as set forth in  claim 42 , wherein the scan head comprises an optical head.  
     
     
       49. A device for scanning a multiplicity of information tracks recorded on a disc- shaped information carrier having a plurality of CAV zones each comprised of a plurality of information tracks spanning a radial portion of a surface of the carrier, the device comprising:      a scan head that generates a scanning beam that scans the information tracks;        a carrier drive that imparts rotational movement of the carrier about a rotational axis, at an angular velocity;        a scan head drive that moves the scan head in a radial direction relative to the information tracks, to thereby vary a radial distance  ( r )  between the scanning beam and the rotational axis; and,        a servo controller that controls the carrier drive in such a manner as to cause the angular velocity to decrease in successive CAV zones located successively further from the rotational axis, and that control the carrier drive to maintain a substantially constant angular velocity within each CAV zone, wherein an average angular velocity decreases as the radial distance  ( r )  increases, and wherein further, the average angular velocity is not inversely proportional to the radial distance  ( r ).    
     
     
       50. The device as set forth in  claim 49 , wherein a linear velocity of the scanning beam relative to an information track being scanned increases as the radial distance ( r )  increases, wherein the linear velocity is not proportional to the radial distance  ( r ).  
     
     
       51. The device as set forth in  claim 49 , wherein an information density decreases in successive CAV zones located at a successively greater distance from the rotational axis, but the information density within each CAV zone is substantially constant.  
     
     
       52. The device as set forth in  claim 49 , wherein the radial portion spanned by successive CAV zones located at a successively greater distance from the rotational axis increases.  
     
     
       53. The device as set forth in  claim 50 , wherein the radial portion spanned by successive CAV zones located at a successively greater distance from the rotational axis increases.  
     
     
       54. The device as set forth in  claim 49 , wherein the information tracks comprise respective convolutions of a spiral track.  
     
     
       55. The device as set forth in  claim 49 , wherein the disc- shaped information carrier comprises an optical disc.    
     
     
       56. The device as set forth in  claim 49 , wherein the disc- shaped information carrier comprises a magneto - optical disc.    
     
     
       57. The device as set forth in  claim 49 , wherein the scanning beam comprises a laser beam.  
     
     
       58. The device as set forth in  claim 49 , wherein the scan head comprises a read/write head.  
     
     
       59. The device as set forth in  claim 49 , wherein the scan head comprises an optical head.  
     
     
       60. A device for scanning a multiplicity of information tracks recorded on a disc- shaped information carrier in a plurality of CLV zones each comprised of a plurality of information tracks spanning a radial portion of a surface of the carrier, the device comprising:      a scan head that generates a scanning beam that scans the information tracks;        a drive system that imparts relative linear movement between the scanning beam and an information track being scanned, at a linear velocity; and,        a servo controller that controls the drive system to increase the linear velocity in successive CLV zones located successively further from a central axis of the carrier, and that controls the drive system to maintain a substantially constant linear velocity within each CLV zone, wherein an average linear velocity of the scanning beam relative to an information track being scanned increases as a radial distance  ( r )  between the scanning beam and the central axis increases, and wherein further, the average linear velocity is not proportional to the radial distance  ( r ).    
     
     
       61. The device as set forth in  claim 60 , wherein an information density decreases in successive CLV zones located at a successively greater radial distance from the central axis, but the information density within each CLV zone is substantially constant.  
     
     
       62. The device as set forth in  claim 60 , wherein the radial span spanned by successive CLV zones located at a successively greater distance from the central axis increases.  
     
     
       63. The device as set forth in  claim 61 , wherein the radial span spanned by successive CLV zones located at a successively greater distance from the central axis increases.  
     
     
       64. The device as set forth in  claim 60 , wherein the information tracks comprise respective convolutions of a spiral track.  
     
     
       65. The device as set forth in  claim 60 , wherein the disc- shaped information carrier comprises an optical disc.    
     
     
       66. The device as set forth in  claim 60 , wherein the disc- shaped information carrier comprises a magneto - optical disc.    
     
     
       67. The device as set forth in  claim 60 , wherein the scanning beam comprises a laser beam.  
     
     
       68. The device as set forth in  claim 60 , wherein the scan head comprises a read/write head.  
     
     
       69. The device as set forth in  claim 60 , wherein the scan head comprises an optical head.  
     
     
       70. A method comprising recording information in a plurality of recording zones on a disc- shaped information carrier, each recording zone being comprised of a plurality of information tracks spanning a radial distance, wherein an information density decreases in successive recording zones located at a successively greater radial distance from a center of the carrier, but the information density within each zone is substantially constant.    
     
     
       71. The method as set forth in  claim 70 , wherein the radial distance spanned by successive zones located at a successively greater radial distance from the center of the carrier increases.  
     
     
       72. The method as set forth in  claim 70 , wherein the information tracks comprise respective convolutions of a spiral track.  
     
     
       73. The method as set forth in  claim 70 , wherein the disc- shaped information carrier comprises an optical disc.    
     
     
       74. The method as set forth in  claim 70 , wherein the disc- shaped information carrier comprises a magneto - optical disc.    
     
     
       75. The method as set forth in  claim 70 , wherein the scanning beam comprises a laser beam.  
     
     
       76. The method as set forth in  claim 70 , wherein the scan head comprises a read/write head.  
     
     
       77. The method as set forth in  claim 70 , wherein the scan head comprises an optical head.  
     
     
       78. A device for scanning a plurality of information tracks recorded on a disc- shaped information carrier, comprising:      a scan head that generates a scanning beam that scans the information tracks;        a scan head drive that moves the scan head in a radial direction relative to the information tracks, to thereby vary a radial distance  ( r )  between the scanning beam and a rotational axis;        a carrier drive that imparts rotational movement of the carrier about the rotational axis, at an angular velocity; and,        a servo controller that controls the carrier drive in such a manner as to cause the angular velocity to decrease as the radial distance  ( r )  increases, wherein the angular velocity is not inversely proportional to the radial distance  ( r ).    
     
     
       79. The device as set forth in  claim 78 , wherein a linear velocity of the scanning beam relative to an information track being scanned increases as the radial distance ( r )  increases, and wherein further, the linear velocity is not proportional to the radial distance  ( r ).  
     
     
       80. The device as set forth in  claim 78 , wherein the information tracks comprise respective convolutions of a spiral track.  
     
     
       81. The device as set forth in  claim 78 , wherein the disc- shaped information carrier comprises an optical disc.    
     
     
       82. The device as set forth in  claim 78 , wherein the disc- shaped information carrier comprises a magneto - optical disc.    
     
     
       83. The device as set forth in  claim 78 , wherein the scanning beam comprises a laser beam.  
     
     
       84. The device as set forth in  claim 78 , wherein the scan head comprises a read/write head.  
     
     
       85. The device as set forth in  claim 78 , wherein the scan head comprises an optical head.  
     
     
       86. A device for scanning a plurality of information tracks recorded on a disc- shaped information carrier, comprising:      a scan head that generates a scanning beam that scans the information tracks;        a carrier drive that imparts rotational movement of the carrier about a rotational axis, at an angular velocity;        a scan head drive that moves the scan head in a radial direction relative to the information tracks, to thereby vary a radial distance  ( r )  between the scanning beam and the rotational axis;        a first servo controller that controls the carrier drive in such a manner as to cause the angular velocity to decrease as the radial distance  ( r )  increases, wherein the angular velocity is not inversely proportional to the radial distance  ( r ) ; and,        a second servo controller that controls the scan head drive in such a manner as to cause a linear velocity of the scanning beam to increase as the radial distance  ( r )  increases, wherein the linear velocity is not proportional to the radial distance  ( r ).    
     
     
       87. The device as set forth in  claim 86 , wherein the information tracks comprise respective convolutions of a spiral track.  
     
     
       88. The device as set forth in  claim 86 , wherein the disc- shaped information carrier comprises an optical disc.    
     
     
       89. The device as set forth in  claim 86 , wherein the disc- shaped information carrier comprises a magneto - optical disc.    
     
     
       90. The device as set forth in  claim 86 , wherein the scanning beam comprises a laser beam.  
     
     
       91. The device as set forth in  claim 86 , wherein the scan head comprises a read/write head.  
     
     
       92. The device as set forth in  claim 86 , wherein the scan head comprises an optical head.  
     
     
       93. A device for scanning a plurality of information tracks recorded on a disc- shaped information carrier, comprising:      a scan head that generates a scanning beam that scans the information tracks;        a carrier drive that imparts rotational movement of the carrier about a rotational axis;        a scan head drive that moves the scan head in a radial direction relative to the information tracks, to thereby vary the distance  ( r )  between the scanning beam and a rotational axis; and,        a servo controller that controls the scan head drive and the carrier device in such a manner as to cause a linear velocity of the scanning beam relative to an information track being scanned to increase as the radial distance  ( r )  increases, wherein the linear velocity is not proportional to the radial distance  ( r ).    
     
     
       94. The device as set forth in  claim 93 , wherein the information tracks comprise respective convolutions of a spiral track.  
     
     
       95. The device as set forth in  claim 93 , wherein the disc- shaped information carrier comprises an optical disc.    
     
     
       96. The device as set forth in  claim 93 , wherein the disc- shaped information carrier comprises a magneto - optical disc.    
     
     
       97. The device as set forth in  claim 93 , wherein the scanning beam comprises a laser beam.  
     
     
       98. The device as set forth in  claim 93 , wherein the scan head comprises a read/write head.  
     
     
       99. The device as set forth in  claim 93 , wherein the scan head comprises an optical head.  
     
     
       100. A method for scanning a plurality of information tracks recorded on a disc- shaped information carrier, comprising:      scanning the information tracks with a scanning beam;        moving the scanning beam in a radial direction relative to the information tracks, to thereby vary a radial distance  ( r )  between the scanning beam and a rotational axis; and,        rotating the carrier about the rotational axis at an angular velocity that decreases as the radial distance  ( r )  increases, wherein the angular velocity is not inversely proportional to the radial distance  ( r ).    
     
     
       101. The method as set forth in  claim 100 , further comprising increasing a linear velocity of the scanning beam relative to an information track being scanned as the radial distance ( r )  increases, wherein the linear velocity is not proportional to the radial distance  ( r ).  
     
     
       102. The method as set forth in  claim 100 , wherein the information tracks comprise respective convolutions of a spiral track.  
     
     
       103. The method as set forth in  claim 100 , wherein the disc- shaped information carrier comprises an optical disc.    
     
     
       104. The method as set forth in  claim 100 , wherein the disc- shaped information carrier comprises a magneto - optical disc.    
     
     
       105. The method as set forth in  claim 100 , wherein the scanning beam comprises a laser beam.  
     
     
       106. A method for scanning a plurality of information tracks recorded on a disc- shaped information carrier, comprising:      scanning the information tracks with a scanning beam;        rotating the carrier about a rotational axis at an angular velocity that decreases as a radial distance  ( r )  between the scanning beam and the rotational axis increases, but at a rate that is not inversely proportional to the radial distance  ( r ) , wherein the angular velocity is not inversely proportional to the radial distance  ( r ) ; and,        moving the scanning beam in a radial direction relative to the information tracks, to thereby vary the radial distance  ( r )  between the scanning beam and the rotational axis, wherein a linear velocity of the scanning beam relative to an information track being scanned increases as the radial distance  ( r )  increases, and wherein further, the linear velocity is not proportional to the radial distance  ( r ).    
     
     
       107. The method as set forth in  claim 106 , further comprising increasing a linear velocity of the scanning beam relative to an information track being scanned as the radial distance ( r )  increases, but at a rate that is not proportion to the radial distance  ( r ) , wherein the linear velocity is not proportional to the radial distance  ( r ).  
     
     
       108. The method as set forth in  claim 106 , wherein the information tracks comprise respective convolutions of a spiral track.  
     
     
       109. The method as set forth in  claim 106 , wherein the disc- shaped information carrier comprises an optical disc.    
     
     
       110. The method as set forth in  claim 106 , wherein the disc- shaped information carrier comprises a magneto - optical disc.    
     
     
       111. The method as set forth in  claim 106 , wherein the scanning beam comprises a laser beam.  
     
     
       112. A method for scanning a plurality of information tracks recorded on a disc- shaped information carrier, comprising:      scanning the information tracks with a scanning beam;        rotating the carrier about a rotational axis; and,        moving the scanning beam in a radial direction relative to the information tracks, to thereby vary a radial distance  ( r )  between the scanning beam and the rotational axis, wherein a linear velocity of the scanning beam relative to an information track being scanned increases as the radial distance  ( r )  increases, and wherein further, the linear velocity is not proportional to the radial distance  ( r ).    
     
     
       113. The method as set forth in  claim 112 , wherein the information tracks comprise respective convolutions of a spiral track.  
     
     
       114. The method as set forth in  claim 112 , wherein the disc- shaped information carrier comprises an optical disc.    
     
     
       115. The method as set forth in  claim 112 , wherein the disc- shaped information carrier comprises a magneto - optical disc.    
     
     
       116. The method as set forth in  claim 112 , wherein the scanning beam comprises a laser beam.  
     
     
       117. A method for scanning a plurality of information tracks recorded on a disc- shaped information carrier, comprising:      scanning the information tracks with a scanning beam;        imparting relative radial movement between the scanning beam and the carrier, to thereby vary a radial distance  ( r )  between the scanning beam and a central axis of the carrier; and,        controlling the imparting in such a manner as to increase a linear velocity of the scanning beam relative to an information track being scanned as the radial distance  ( r )  increases, wherein the linear velocity is not proportional to the radial distance  ( r ).    
     
     
       118. The method as set forth in  claim 117 , wherein an information density of the carrier varies as a function of the radial distance ( r ).  
     
     
       119. The method as set forth in  claim 117 , wherein the information tracks comprise respective convolutions of a spiral track.  
     
     
       120. The method as set forth in  claim 117 , wherein the disc- shaped information carrier comprises an optical disc.    
     
     
       121. The method as set forth in  claim 117 , wherein the disc- shaped information carrier comprises a magneto - optical disc.    
     
     
       122. The method as set forth in  claim 117 , wherein the scanning beam comprises a laser beam.  
     
     
       123. A method for scanning a multiplicity of information tracks recorded on a disc- shaped information carrier having a plurality of CAV zones each comprised of a plurality of information tracks spanning a radial portion of a surface of the carrier, the method comprising:      scanning the information tracks with a scanning beam;        rotating the carrier about a rotational axis, at an angular velocity;        moving the scanning beam in a radial direction relative to the information tracks, to thereby vary a radial distance  ( r )  between the scanning beam and the rotational axis; and,        controlling the rotating in such a manner as to cause the angular velocity to decrease in successive CAV zones located successively further from the rotational axis, while maintaining a substantially constant angular velocity within each CAV zone, wherein an average angular velocity increases as the radial distance  ( r )  increases, and wherein further, the average angular velocity is not inversely proportional to the radial distance  ( r ).    
     
     
       124. The method as set forth in  claim 123 , further comprising increasing a linear velocity of the scanning beam relative to an information track being scanned as the radial distance ( r )  increases, but at a rate that is not proportional to the radial distance  ( r ) , wherein the linear velocity is not proportional to the radial distance  ( r ).  
     
     
       125. The method as set forth in  claim 123 , wherein an information density decreases in successive CAV zones located at a successively greater distance from the rotational axis, but the information density within each CAV zone is substantially constant.  
     
     
       126. The method as set forth in  claim 123 , wherein the radial portion spanned by successive CAV zones located at a successively greater distance from the rotational axis increases.  
     
     
       127. The method as set forth in  claim 125 , wherein the radial portion spanned by successive CAV zones located at a successively greater distance from the rotational axis increases.  
     
     
       128. The method as set forth in  claim 123 , wherein the information tracks comprise respective convolutions of a spiral track.  
     
     
       129. The method as set forth in  claim 123 , wherein the disc- shaped information carrier comprises an optical disc.    
     
     
       130. The method as set forth in  claim 123 , wherein the disc- shaped information carrier comprises a magneto - optical disc.    
     
     
       131. The method as set forth in  claim 123 , wherein the scanning beam comprises a laser beam.  
     
     
       132. A method for scanning a multiplicity of information tracks recorded on a disc- shaped information carrier in a plurality of CLV zones each comprised of a plurality of information tracks spanning a radial portion of a surface of the carrier, the method comprising:      scanning the information tracks with a scanning beam;        imparting relative linear movement between the scanning beam and an information track being scanned, at a linear velocity; and,        controlling the imparting in such a manner as to increase the linear velocity in successive CLV zones located successively further from a central axis of the carrier, while maintaining a substantially constant linear velocity within each CLV zone, wherein the controlling is performed in such a manner as to cause an average linear velocity of the scanning beam relative to an information track being scanned to increase as the radial distance  ( r )  increases, and wherein further, the average linear velocity is not proportional to the radial distance  ( r ).    
     
     
       133. The method as set forth in  claim 132 , wherein an information density decreases in successive CLV zones located at a successively greater radial distance from the central axis, but the information density within each CLV zone is substantially constant.  
     
     
       134. The method as set forth in  claim 132 , wherein the radial portion spanned by successive CLV zones located at a successively greater distance from the central axis increases.  
     
     
       135. The method as set forth in  claim 133 , wherein the radial portion spanned by successive CLV zones located at a successively greater distance from the central axis increases.  
     
     
       136. The method as set forth in  claim 133 , wherein the information tracks comprise respective convolutions of a spiral track.  
     
     
       137. The method as set forth in  claim 133 , wherein the disc- shaped information carrier comprises an optical disc.    
     
     
       138. The method as set forth in  claim 133 , wherein the disc- shaped information carrier comprises a magneto - optical disc.    
     
     
       139. The method as set forth in  claim 133 , wherein the scanning beam comprises a laser beam.  
     
     
       140. A device for recording information on a disc- shaped information carrier, comprising:      means for recording information in a plurality of recording zones on the carrier, each recording zone being compared of a plurality of information tracks spanning a radial distance; and,        means for controlling the means for recording in such a manner as to decrease an information density in successive recording zones located at a successively greater radial distance from a center of the carrier, while maintaining the information density within each zone substantially constant.      
     
     
       141. The device as set forth in  claim 140 , wherein the radial distance spanned by successive zones located at a successively greater radial distance from the center of the carrier increases.  
     
     
       142. The device as set forth in  claim 140 , wherein the information tracks comprise respective convolutions of a spiral track.  
     
     
       143. The device as set forth in  claim 140 , wherein the disc- shaped information carrier comprises an optical disc.    
     
     
       144. The device as set forth in  claim 140 , wherein the disc- shaped information carrier comprises a magneto - optical disc.    
     
     
       145. A method for scanning a plurality of information tracks recorded on a disc- shaped information carrier, comprising:      scanning the information tracks with a scanning beam;        rotating the carrier about a rotational axis, at an angular velocity;        moving the scanning beam in a radial direction relative to the information tracks, to thereby vary a radial distance  ( r )  between the scanning beam and the rotational axis; and,        controlling the rotating in such a manner as to cause the angular velocity to decrease as the radial distance  ( r )  increases, wherein the angular velocity is not inversely proportional to the radial distance  ( r ).    
     
     
       146. The method as set forth in  claim 145 , further comprising increasing a linear velocity of the scanning beam relative to an information track being scanned as the radial distance ( r )  increases, wherein the linear velocity is not proportional to the radial distance  ( r ).  
     
     
       147. The method as set forth in  claim 145 , wherein the information tracks comprise respective convolutions of a spiral track.  
     
     
       148. The method as set forth in  claim 145 , wherein the disc- shaped information carrier comprises an optical disc.    
     
     
       149. The method as set forth in  claim 145 , wherein the disc- shaped information carrier comprises a magneto - optical disc.    
     
     
       150. The method as set forth in  claim 145 , wherein the scanning beam comprises a laser beam.  
     
     
       151. A method for scanning a plurality of information tracks recorded on a disc- shaped information carrier, comprising:      scanning the information tracks with a scanning beam;        rotating the carrier about a rotational axis, at an angular velocity;        moving the scanning beam in a radial direction relative to the information tracks, to thereby vary a radial distance  ( r )  between the scanning beam and the rotational axis;        controlling the rotating in such a manner as to cause the angular velocity to decrease as the radial distance  ( r )  increases, wherein the angular velocity is not inversely proportional to the radial distance  ( r ) ; and,        controlling the moving in such a manner as to cause a linear velocity of the scanning beam relative to an information track being scanned to increase as the radial distance  ( r )  increases, wherein the linear velocity is not proportional to the radial distance  ( r ).    
     
     
       152. The method as set forth in  claim 151 , wherein the information tracks comprise respective convolutions of a spiral track.  
     
     
       153. The method as set forth in  claim 151 , wherein the disc- shaped information carrier comprises an optical disc.    
     
     
       154. The method as set forth in  claim 151 , wherein the disc- shaped information carrier comprises a magneto - optical disc.    
     
     
       155. The method as set forth in  claim 151 , wherein the scanning beam comprises a laser beam.  
     
     
       156. A method for scanning a plurality of information tracks recorded on a disc- shaped information carrier, comprising:      scanning the information tracks with a scanning beam;        rotating the carrier about a rotational axis;        moving the scanning beam in a radial direction relative to the information tracks, to thereby vary the distance  ( r )  between the scanning beam and the rotational axis; and        controlling the rotating and moving in such a manner as to cause a linear velocity of the scanning beam relative to an information track being scanned to increase as the radial distance  ( r )  increases, wherein the linear velocity is not proportional to the radial distance  ( r ).    
     
     
       157. The method as set forth in  claim 156 , wherein the information tracks comprise respective convolutions of a spiral track.  
     
     
       158. The method as set forth in  claim 156 , wherein the disc- shaped information carrier comprises an optical disc.    
     
     
       159. The method as set forth in  claim 156 , wherein the disc- shaped information carrier comprises a magneto - optical disc.    
     
     
       160. The method as set forth in  claim 156 , wherein the scanning beam comprises a laser beam.  
     
     
       161. A device for scanning a plurality of information tracks recorded on a disc- shaped information carrier, comprising:      means for scanning the information tracks with a scanning beam;        means for moving the scanning beam in a radial direction relative to the information tracks, to thereby vary a radial distance  ( r )  between the scanning beam and a rotational axis; and,        means for rotating the carrier about the rotational axis at an angular velocity that decreases as the radial distance  ( r )  increases, wherein the angular velocity is not inversely proportional to the radial distance  ( r ).    
     
     
       162. The device as set forth in  claim 161 , further comprising means for increasing a linear velocity of the scanning beam relative to an information track being scanned as the radial distance ( r )  increases, but at a rate that is not proportional to the radial distance  ( r ) , wherein the linear velocity is not proportional to the radial distance  ( r ).  
     
     
       163. A device for scanning a plurality of information tracks recorded on a disc- shaped information carrier, comprising:      means for scanning the information tracks with a scanning beam;        means for rotating the carrier about a rotational axis at an angular velocity that decreases as a radial distance  ( r )  between the scanning beam and the rotational axis increases, but at a rate that i snot inversely proportional to the radial distance  ( r ) , wherein the angular velocity is not inversely proportional to the radial distance  ( r ) ; and,        means for moving the scanning beam in a radial direction relative to the information tracks, to thereby vary the radial distance  ( r )  between the scanning beam and the rotational axis, wherein a linear velocity of the scanning beam relative to an information track being scanned increases as the radial distance  ( r )  increases, wherein the linear velocity is not proportional to the radial distance  ( r ).    
     
     
       164. A device for scanning a plurality of information tracks recorded on a disc- shaped information carrier, comprising:      means for scanning the information tracks with a scanning beam;        means for rotating the carrier about a rotational axis; and,        means for moving the scanning beam in a radial direction relative to the information tracks, to thereby vary a radial distance  ( r )  between the scanning beam and the rotational axis, wherein a linear velocity of the scanning beam relative to an information track being scanned increases as the radial distance  ( r )  increases, wherein the linear velocity is not proportional to the radial distance  ( r ).    
     
     
       165. A device for scanning a plurality of information tracks recorded on a disc- shaped information carrier, comprising:      means for scanning the information tracks with a scanning beam;        means for imparting relative radial movement between the scanning beam and the carrier, to thereby vary a radial distance  ( r )  between the scanning beam and a central axis of the carrier; and,        means for controlling the means for imparting in such a manner as to increase a linear velocity of the scanning beam relative to an information track being scanned as the radial distance  ( r )  increases, wherein the linear velocity is not proportional to the radial distance  ( r ).    
     
     
       166. The device as set forth in  claim 165 , wherein an information density of the carrier varies as a function of the radial distance ( r ).  
     
     
       167. A device for scanning a multiplicity of information tracks recorded on a disc- shaped information carrier having a plurality of CAV zones each comprised of a plurality of information tracks spanning a radial portion of a surface of the carrier, the device comprising:      means for scanning the information tracks with a scanning beam;        means for rotating the carrier about a rotational axis, at an angular velocity;        means for moving the scanning beam in a radial direction relative to the information tracks, to thereby vary a radial distance  ( r )  between the scanning beam and the rotational axis; and,        means for controlling the means for rotating in such a manner as to cause the angular velocity to decrease in successive CAV zones located successively further from the rotational axis, while maintaining a substantially constant angular velocity within each CAV zone, wherein an average angular velocity increases as the radial distance  ( r )  increases, and wherein further, the average angular velocity is not inversely proportional to the radial distance  ( r ).    
     
     
       168. The device as set forth in  claim 167 , further comprising means for increasing a linear velocity of the scanning beam relative to an information track being scanned as the radial distance ( r ) increases, wherein the linear velocity is not proportional to the radial distance ( r ).  
     
     
       169. The device as set forth in  claim 167 , wherein an information density decreases in successive CAV zones located at a successively greater distance from the rotational axis, but the information density within each CAV zone is substantially constant.  
     
     
       170. The device as set forth in  claim 167 , wherein the radial portion spanned by successive CAV zones located at a successively greater distance from the rotational axis increases.  
     
     
       171. The device as set forth in  claim 169 , wherein the radial portion spanned by successive CAV zones located at a successively greater distance from the rotational axis increases.  
     
     
       172. A device for scanning a multiplicity of information tracks recorded on a disc- shaped information carrier in a plurality of CLV zones each comprised of a plurality of information tracks spanning a radial portion of a surface of the carrier, the device comprising:      means for scanning the information tracks with a scanning beam;        means for imparting relative linear movement between the scanning beam and an information track being scanned, at a linear velocity; and,        means for controlling the means for imparting in such a manner as to increase the linear velocity in successive CLV zones located successively further from a central axis of the carrier, while maintaining a substantially constant linear velocity within each CLV zone, wherein the means for controlling causes an average linear velocity of the scanning beam relative to an information track being scanned to increase as the radial distance  ( r )  increases, and wherein further, the average linear velocity is not proportional to the radial distance  ( r ).    
     
     
       173. The device as set forth in  claim 172 , wherein an information density decreases in successive CLV zones located at a successively greater radial distance from the central axis, but the information density within each CLV zone is substantially constant.  
     
     
       174. The device as set forth in  claim 172 , wherein the radial portion spanned by successive CLV zones located at a successively greater distance from the central axis increases.  
     
     
       175. The device as set forth in  claim 173 , wherein the radial portion spanned by successive CLV zones located at a successively greater distance from the central axis increases.  
     
     
       176. A device for scanning a multiplicity of information tracks recorded on a disc- shaped information carrier in a plurality of CLV zones each comprised of a plurality of information tracks spanning a radial portion of a surface of the carrier, the device comprising:      scanning means for generating a scanning beam for scanning the information tracks;        rotating means for rotating the carrier about a rotational axis, at an angular velocity;        moving means for moving the scanning beam in a radial direction relative to the information tracks, to thereby vary a radial distance  ( r )  between the scanning beam and the rotational axis; and,        control means for controlling the rotating means and the moving means in such a manner as to substantially increase a linear velocity of the scanning beam relative to an information track being scanned as the scanning beam is moved from an innermost track towards an outermost track, the control means being arranged to set the linear velocity at a substantially constant linear velocity determined by the CLV zone of the information track being scanned,        wherein the control means causes the angular velocity of the scanning beam relative to an information track being scanned to change as the radial distance  ( r )  increases.      
     
     
       177. The device as set forth in  claim 176 , wherein the angular velocity within each CLV zone is limited to a maximum angular velocity for that CLV zone, and wherein further, the angular velocity of an outermost track of a given one of the CLV zones is substantially equal to the angular velocity of an information track of an adjacent one of the CLV ones.  
     
     
       178. The device as set forth in  claim 176 , wherein the angular velocity within each CLV zone increases from an initial angular velocity at an innermost track of that CLV zone to a maximum angular velocity at an outermost track of that CLV zone.  
     
     
       179. The device as set forth in  claim 178 , wherein the maximum angular velocity of one of the CLV zones is substantially equal to the initial angular velocity of an adjacent one of the CLV zones.  
     
     
       180. A device for scanning a multiplicity of information tracks recorded on a disc- shaped information carrier in a plurality of CLV zones each comprised of a plurality of information tracks spanning a radial portion of a surface of the carrier, the device comprising:      scanning means for generating a scanning beam for scanning the information tracks;        rotating means for rotating the carrier about a rotational axis, at an angular velocity;        moving means for moving the scanning beam in a radial direction relative to the information tracks, to thereby vary a radial distance  ( r )  between the scanning beam and the rotational axis; and,        control means for controlling the rotating means and the moving means in such a manner as to substantially increase a linear velocity of the scanning beam relative to an information track being scanned as the scanning beam is moved from an innermost track towards an outermost track, the control means being arranged to set the linear velocity at a substantially constant linear velocity determined by the CLV zone of the information track being scanned,        wherein the radial portion spanned by an outermost one of the CLV zones is greater than the radial portion spanned by an innermost one of the CLV zone; and,        wherein the angular velocity decreases substantially at least within the outermost one of the CLV zones.      
     
     
       181. The device as set forth in  claim 180 , wherein the radial portion spanned by the CLV zones increases with increasing distance ( r ).  
     
     
       182. A device for scanning a multiplicity of information tracks recorded on a disc- shaped information carrier in a plurality of CLV zones each comprised of a plurality of information tracks spanning a radial portion of a surface of the carrier, the device comprising:      a scan head that generates a scanning beam that scans the information tracks;        a carrier drive that rotates the carrier about a rotational axis, at an angular velocity;        a scan head drive that moves the scan head in a radial direction relative to the information tracks, to thereby vary a radial distance  ( r )  between the scanning beam and the rotational axis; and,        a servo controller that controls the carrier drive and the scan head drive in such a manner as to substantially increase a linear velocity of the scanning beam relative to an information track being scanned as the scanning beam is moved from an innermost track towards an outermost track, the servo controller being arranged to set the linear velocity at a substantially constant linear velocity determined by the CLV zone of the information track being scanned, wherein the servo controller causes the angular velocity of the scanning beam relative to an information track being scanned to change substantially as the radial distance  ( r )  increases.      
     
     
       183. The device as set forth in  claim 182 , wherein the angular velocity within each CLV zone is limited to a maximum angular velocity for that CLV zone, and wherein further, the angular velocity of an outermost track of a given one of the CLV zones is substantially equal to the angular velocity of an innermost track of an adjacent one of the CLV ones.  
     
     
       184. The device as set forth in  claim 182 , wherein the angular velocity within each CLV zone increases from an initial angular velocity at an innermost track of that CLV zone to a maximum angular velocity at an outermost track of that CLV zone.  
     
     
       185. The device as set forth in  claim 183 , wherein the maximum angular velocity of one of the CLV zones is substantially equal to the initial angular velocity of an adjacent one of the CLV zones.  
     
     
       186. A device for scanning a multiplicity of information tracks recorded on a disc- shaped information carrier in a plurality of CLV zones each comprised of a plurality of information tracks spanning a radial portion of a surface of the carrier, the device comprising:      a scan head that generates a scanning beam that scans the information tracks;        a carrier drive that rotates the carrier about a rotational axis, at an angular velocity;        a scan head drive that moves the scan head in a radial direction relative to the information tracks, to thereby vary a radial distance  ( r )  between the scanning beam and the rotational axis; and,        a servo controller that controls the carrier drive and the scan head drive in such a manner as to substantially increase the linear velocity of the scanning beam relative to an information track being scanned as the scanning beam is moved from an innermost track towards an outermost track, the servo controller being arranged to set the linear velocity at a substantially constant linear velocity determined by the CLV zone of the information track being scanned,        wherein the radial portion spanned by an outermost one of the CLV zones is greater than the radial portion spanned by an innermost one of the CLV zones; and,        wherein the angular velocity decreases substantially at least within the outermost one of the CLV zones.      
     
     
       187. The device as set forth in  claim 186 , wherein the radial portion spanned by the CLV zones increases with increasing distance ( r ).  
     
     
       188. A method for scanning a multiplicity of information tracks recorded on a disc- shaped information carrier in a plurality of CLV zones each comprised of a plurality of information tracks spanning a radial portion of a surface of the carrier, the method comprising:      generating a scanning beam for scanning the information tracks;        rotating the carrier about a rotational axis, at an angular velocity;        moving the scanning beam in a radial direction relative to the information tracks, to thereby vary a radial distance  ( r )  between the scanning beam and the rotational axis; and,        controlling the rotating and the moving to substantially increase a linear velocity of the scanning beam relative to an information track being scanned as the scanning beam is moved from an innermost track towards an outermost track; to set the linear velocity at a substantially constant linear velocity determined by the CLV zone of the information track being scanned; and, to cause the angular velocity of the scanning beam relative to an information track being scanned to change substantially as the radial distance  ( r )  increases.      
     
     
       189. The method as set forth in  claim 188 , wherein the angular velocity within each CLV zone is limited to a maximum angular velocity for that CLV zone, and wherein further, the angular velocity of an outermost track of a given one of the CLV zones is substantially equal to the angular velocity of an innermost track of an adjacent one of the CLV ones.  
     
     
       190. The method as set forth in  claim 188 , wherein the angular velocity within each CLV zone increases from an initial angular velocity at an innermost track of that CLV zone to a maximum angular velocity at an outermost track of that CLV zone.  
     
     
       191. The method as set forth in  claim 188 , wherein the maximum angular velocity of one of the CLV zones is substantially equal to the initial angular velocity of an adjacent one of the CLV zones.  
     
     
       192. A method for scanning a multiplicity of information tracks recorded on a disc- shaped information carrier in a plurality of CLV zones each comprised of a plurality of information tracks spanning a radial portion of a surface of the carrier, the method comprising:      generating a scanning beam for scanning the information tracks;        rotating the carrier about a rotational axis, at an angular velocity;        moving the scanning beam in a radial direction relative to the information tracks, to thereby vary a radial distance  ( r )  between the scanning beam and the rotational axis; and,        controlling the rotating and the moving to substantially increase a linear velocity of the scanning beam relative to an information track being scanned as the scanning beam is moved from an innermost track towards an outermost track, and to set the linear velocity at a substantially constant linear velocity determined by the CLV zone of the information track being scanned,        wherein the radial portion spanned by an outermost one of the CLV zones is greater than the radial portion spanned by an innermost one of the CLV zones; and,        wherein the angular velocity decreases substantially at least within the outermost one of the CLV zones.      
     
     
       193. The method as set forth in  claim 192 , wherein the radial portion spanned by the CLV zones increases with increasing distance ( r ).