Optical record carrier and scanning apparatus

Abstract

An optical record carrier ( 1 ) is provided with tracks having a groove ( 4 ) wobbled in a radial direction and predetermined positions ( 18 ) along the track. Embossed pits ( 19 ) at the predetermined positions represent addressing information. The phase of the wobble near the predetermined positions depends on whether a pit is present ( 19 ) on a predetermined position or not ( 20 ).

1 . An optical record carrier comprising a recording layer having substantially parallel tracks for recording information in a pattern of optically detectable marks, the tracks being provided with wobbled grooves and predetermined positions along the tracks, on which positions information is stored in the form of pits, characterized in that the phase of the wobble at the predetermined positions is adapted to the presence of a pit at such a predetermined position.  
     
     
         2 . Optical record carrier according to  claim 1 , wherein the wobble has a minimum value at a predetermined position with pit and a maximum value at a predetermined position without pit.  
     
     
         3 . Optical record carrier according to  claim 1 , wherein the predetermined positions are grouped in series and the wobble in between the series of predetermined positions in the track direction represents information.  
     
     
         4 . Optical record carrier according to  claim 3 , wherein the information in the wobble is encoded by phase-shift keying.  
     
     
         5 . Optical record carrier according to  claim 1 , wherein the predetermined positions are arranged between neighbouring grooves.  
     
     
         6 . Optical record carrier according to  claim 5 , wherein the phase of the wobble of only one of the neighbouring grooves is adapted to the presence of a pit at a predetermined position.  
     
     
         7 . Optical record carrier according to  claim 5 , wherein the phases of both neighbouring grooves are adapted to the presence of a pit at a predetermined position and the wobble of both neighbouring grooves is in anti-phase.  
     
     
         8 . Optical record carrier according to  claim 1 , wherein the predetermined positions are grouped in doublets of two neighbouring predetermined positions, and one pit is present in each doublet.  
     
     
         9 . Optical record carrier according to  claim 1 , wherein land portions are arranged between neighbouring grooves, and land portions are alternatingly provided with pits and without pits.  
     
     
         10 . An apparatus for scanning an optical record carrier having substantially parallel tracks for recording user information in a pattern of optically detectable marks, the tracks being provided with wobbled grooves and predetermined positions along the tracks, on which information is stored in the form of pits, the apparatus comprising an optical system for scanning tracks by a radiation beam, a detector for detecting a radiation beam coming from the record carrier, and a first signal processor for deriving information represented by the pits from an output signal of the detector, characterized in that the apparatus is provided with a second signal processor for deriving information represented by the wobble from an output signal of the detector, and selector means for forming an information signal from an information output signal of the first signal processor and the second signal processor.  
     
     
         11 . Apparatus according to  claim 10 , wherein the selector means is operatively connected to select between the information output signals based on a quality of output signals of the detector.  
     
     
         12 . Apparatus according to  claim 10 , wherein the information represented by the pits is at least partly identical to the information represented by the wobble.  
     
     
         13 . A method of scanning an optical record carrier having substantially parallel tracks for recording user information in a pattern of optically detectable marks, the tracks being provided with wobbled grooves and predetermined positions along the tracks, on which information is stored in the form of pits, characterized in that during scanning an information signal is derived from one of the pits, the wobble, and the pits and the wobble, in dependence on selection criteria.