Abstract:
A disk recording apparatus for recording data to a disk is disclosed. The apparatus includes: a reading and writing element for emitting a read beam onto the disk to read out recorded data therefrom while emitting a plurality of write beams simultaneously onto the disk to record data thereto in parallel; and a controlling element for controlling where to emit on the disk the plurality of write beams in accordance with the data read out by the reading and writing element.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    The present invention relates to a method for recording data to a disk as well as to a disk recording apparatus for recording data based on that method.  
           [0002]    In setups where data are written to a disk using a plurality of beams, data may be written to an unrecorded region that is scanned immediately before a given location where data have already been written by means of a beam. In such cases, it is preferred, for the purpose of recording data at high density with high precision, to write the data in such a manner that the end of the data to be written to the unrecorded region continues seamlessly and in nonoverlapping fashion to the beginning of the data in the ensuing recorded region.  
           [0003]    Conventionally, however, it has been very difficult precisely to match on the disk the start of the data in any recorded region with the end of data to be recorded to an unrecorded region preceding that region.  
           [0004]    At present, position data superposed on the wobbling grooves on the disk are read for use in determining where unrecorded regions exist on the disk surface. The retrieval of such position data allows for about a 10-percent read error, which does not contribute to improving accuracy.  
           [0005]    Where the end of the data to be recorded is adjusted for data region coincidence on the basis of the position data mentioned above, any failure to read the position data correctly can result in a data overlap or a data gap with regard to the beginning of the data in recorded regions. The data overlap destroys what is already written in recorded regions. Both the data overlap and the data gap deviate from criteria for recording data properly to the disk and thereby incur the risk of failing to read data correctly from the disk.  
           [0006]    If special regions called link regions are established between each recorded region and an unrecorded region, the data retrieved from the link regions during data read operations are regarded as unreliable and are thus not used. As a result, a significant amount of recording capacity is lost, much to the detriment of actually writing data to the disk.  
         SUMMARY OF THE INVENTION  
         [0007]    The present invention has been made in view of the above circumstances and provides a method for recording data to a disk at high density with high precision, and a disk recording apparatus for recording data to the disk based on that method.  
           [0008]    In carrying out the invention and according to a first aspect thereof, there is provided a disk recording apparatus for recording data to a disk, including: reading and writing element for emitting a read beam onto the disk to read out recorded data therefrom while emitting a plurality of write beams simultaneously onto the disk to record data thereto in parallel; and controlling element for controlling where to emit on the disk the plurality of write beams in accordance with the data read out by the reading and writing element.  
           [0009]    The inventive structure outlined above allows data to be written with precision and in parallel to necessary regions on the disk by use of multiple write beams.  
           [0010]    In one preferred structure according to the invention, the reading and writing element may further include: beam-condensing element arranged to face the disk; read beam emitting element for emitting the read beam onto the disk through the beam-condensing element; a plurality of write beam emitting element for emitting the plurality of write beams onto the disk through the beam-condensing element; and reading element for reading out the recorded data from the disk by detecting intensity of light gotten by condensing the read beam reflected on the disk with the beam-condensing element.  
           [0011]    The reading and writing element of the preferred structure above may carry out two processes in parallel: reading data from the disk by use of the read beam, and writing data to the disk using a plurality of write beams.  
           [0012]    In another preferred structure according to the invention, the reading and writing element may further include: beam-condensing element arranged to face the disk; beam-emitting element for emitting a beam to the beam-condensing element from the opposite side to the disk; beam-splitting element for splitting the beam emitted from the beam-emitting element into the read beam and the plurality of write beams, and emitting the read beam and the plurality of write beams onto the disk through the beam-condensing element; beam dose adjusting element for adjusting a dose of each of the read beam and the plurality of write beams; and reading element for reading out the recorded data from the disk by detecting intensity of light gotten by condensing the read beam reflected on the disk with the beam-condensing element.  
           [0013]    According to a second aspect of the invention, there is provided a disk recording method for recording data to a disk, including: first step where emitting a read beam onto the disk to read out recorded data therefrom while emitting a plurality of write beams simultaneously onto the disk to record data thereto in parallel; and second step where controlling where to emit on the disk the plurality of write beams in accordance with the data read out in the first step.  
           [0014]    The inventive method outlined above permits easy and reliable control over recording of data in parallel to the disk using multiple write beams.  
           [0015]    In one preferred variation of the inventive method above, the first step may further include the steps of: emitting the read beam onto the disk through beam-condensing element arranged to face the disk; reading out the recorded data from the disk by detecting intensity of light gotten by condensing the read beam reflected on the disk with the beam-condensing element; and emitting the plurality of write beams onto the disk through the beam-condensing element.  
           [0016]    In another preferred variation of the inventive method above, the first step may further include the steps of: emitting a beam to beam-condensing element arranged to face the disk from the opposite side to the disk; splitting the emitted beam into the read beam and the plurality of write beams; adjusting a dose of each of the read beam and the plurality of write beams; emitting the read beam and the plurality of write beams adjusted in doses onto the disk through the beam-condensing element; and reading out the recorded data from the disk by detecting intensity of light gotten by condensing the read beam reflected on the disk with the beam-condensing element.  
           [0017]    The disk recording apparatus and disk recording method according to the invention allow data to be written precisely and in parallel to desired regions on the disk using a plurality of write beams, whereby high-density data recording is implemented at high speed with high precision on the disk.  
           [0018]    The above and other objects, features and advantages of the present invention will become apparent from the following description and the appended claims, taken in conjunction with the accompanying drawings in which like parts or elements denoted by like reference symbols. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0019]    [0019]FIG. 1 is a block diagram showing an overall structure of a disk recording apparatus embodying this invention;  
         [0020]    [0020]FIG. 2 is a schematic view depicting a first structure of an optical pickup shown in FIG. 1;  
         [0021]    [0021]FIG. 3 is a schematic view illustrating a second structure of the optical pickup shown in FIG. 1; and  
         [0022]    [0022]FIG. 4 is an explanatory view explaining how the disk recording apparatus of FIG. 1 typically operates. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0023]    Preferred embodiments of this invention will now be described in detail with reference to the accompanying drawings. Throughout the drawings, like reference numerals designate like or corresponding parts.  
         [0024]    [0024]FIG. 1 is a block diagram showing an overall structure of a disk recording apparatus  30  embodying this invention. As shown in FIG. 1, the disk recording apparatus  30  includes a spindle motor  3  for rotating an optical disk  1 , an optical pickup  5 , an RF amplifier  7 , a decoder  9 , a system controller  10 , a buffer memory  11 , an interface unit  12 , an encoder  13 , a write signal controller  15 , a laser driving unit  17 , a servo control unit  19 , and a servo driving unit  21 .  
         [0025]    The spindle motor  3  is connected to the servo driving unit  21 . The optical pickup  5  is connected to the servo driving unit  21  and laser driving unit  17 . The RF amplifier  7  is connected to the optical pickup  5 , and the decoder  9  is connected to the RF amplifier  7 . The system controller  10  is connected to the decoder  9 , encoder  13 , write signal controller  15 , and servo control unit  19 .  
         [0026]    The buffer memory  11  is connected to the decoder  9 . The interface  12  is connected to the buffer memory  11  and an externally furnished personal computer (PC) or the like. The encoder  13  is connected to the buffer memory  11  and write signal controller  15  which in turn is connected to the RF amplifier  7 . The laser driving unit  17  is connected to the write signal controller  15 . The servo control unit  19  is connected to the RF amplifier  7  and decoder  9 . The servo driving unit  21  is connected to the servo control unit  19 .  
         [0027]    The disk recording apparatus  30  of the above-outlined structure admits write data into the buffer memory  11  from the externally connected PC or the like through the interface unit  12 , the write data being destined to be recorded to the optical disk  1 . The write signal controller  15  writes the data to the optical disk  1  by controlling the laser driving unit  17  and servo control unit  19  in accordance with the write data encoded by the encoder  13 . The encoder  13 , write signal controller  15  and servo control unit  19  operate in concert under control of the system controller  10 .  
         [0028]    A signal read by the optical pickup  5  from the optical disk  1  is fed to the decoder  9  via the RF amplifier  7 . After being decoded by the decoder  9 , the signal is placed into the buffer memory  11 .  
         [0029]    [0029]FIG. 2 is a schematic view depicting a first structure of the optical pickup  5  shown in FIG. 1. As illustrated in FIG. 2, the optical pickup  5  includes a lens  51 , a beam splitter  52 , a read laser diode LR, write laser diodes LW 1  through LW 3 , a read photodiode PR, and write photodiodes P 1  through P 3 .  
         [0030]    The lens  51  is furnished in a manner facing the optical disk  1  to which to write data. Each of the read laser diode LR and write laser diodes LW 1  through LW 3  emits a laser beam onto the lens  51 .  
         [0031]    The read laser diode LR emits a read beam R by which to read recorded data from the optical disk  1 . The write laser diodes LW 1  through LW 3  respectively emit write beams W 1  through W 3  by which to write data to the optical disk  1 . How these laser beams are controlled will be discussed later in more detail.  
         [0032]    The beam splitter  52  is interposed between the four laser diodes (LD) on the one hand and the lens  51  on the other hand. The read photodiode PR and write photodiodes P 1  through P 3  are provided so as to receive reflected light beams from the beam splitter  52 .  
         [0033]    In the optical pickup  5  of the above-outlined structure, the read laser diode LR emits the read beam R onto the optical disk  1  via the beam splitter  52  and lens  51 . The write laser diodes LW 1  through LW 3  emit the write beams W 1  through W 3  to the optical disk  1  via the beam splitter  52  and lens  51 .  
         [0034]    The laser beam emitted by the read laser diode LR is controlled in accordance with a control signal SR from the laser driving unit  17 . The laser beams emitted by the write laser diodes LW 1  through LW 3  are controlled individually by use of control signals SW 1  through SW 3  from the laser driving unit  17 . That is, the write laser diodes LW 1  through LW 3  write data in parallel to the optical disk  1  by controlling in intensity the emitted write beams W 1  through W 3  in accordance with the control signals SW 1  through SW 3 .  
         [0035]    The read beam R and the write beams W 1  through W 3  are reflected by the optical disk  1  before entering the beam splitter  52  through the lens  51 . For purpose of simplification and illustration, FIG. 2 shows the reflected light paths not as they actually occur but in a simply sketched fashion. The same applies to what is shown in FIG. 3, to be discussed later.  
         [0036]    In the above setup, the laser beams are reflected by the beam splitter  52 . The read beam R is then received by the read photodiode PR while the write beams W 1  through W 3  are received by the write photodiodes P 1  through P 3 . In turn, the read photodiode PR generates a signal RSR reflecting the amount of the light received, before supplying the signal RSR to the RF amplifier  7 . The write photodiodes PI through P 3  generate signals RS 1  through RS 3  reflecting the amounts of the light received, before feeding the signals RS 1  through RS 3  to the RF amplifier  7 .  
         [0037]    The optical pickup  5  may be replaced by an alternative optical pickup  6  having a second structure shown in FIG. 3. As depicted in FIG. 3, the optical pickup  6  has basically the same structure as the optical pickup  5  of FIG. 2. The difference is that the beam splitter  52  is furnished with a liquid crystal shutter  62  and that the read laser diode LR and write laser diodes LW 1  through LW 3  are replaced by a laser diode  60  and a diffraction grating  61 .  
         [0038]    In the optical pickup  6  of the above-outlined structure, the laser diode  60  emits a single laser beam based on a control signal LC supplied by the laser driving unit  17 . The emitted laser beam is diffracted by the diffraction grating  61 . The liquid crystal shutter  62  opens and shuts three optical paths independently in accordance with the control signals SW 1  through SW 3  supplied illustratively by the laser driving unit  17 .  
         [0039]    In the above setup, the laser diode  60  controls in intensity the emitted laser beam in accordance with the control signal LC, and the openings of the liquid crystal shutter  62  are regulated in keeping with the control signals SW 1  through SW 3 . The arrangements permit independent control of the write beams W 1  through W 3  in intensity, whereby data are written in parallel to the optical disk  1 .  
         [0040]    Described below with reference to FIG. 4 is how the disk recording apparatus  30  embodying the invention typically operates. In FIG. 4, illustratively three write beams W 1  through W 3  are shown to be used to write data in parallel to the optical disk  1  where tracks TR are formed in spiral fashion. Unrecorded tracks are indicated by broken lines. It should be noted that the number of write beams is not limited to three; the invention applies irrespective of the number of beams in use. In FIG. 4, the read beam R and the write beams W 1  through W 3  are shown two tracks apart from one another. However, this is not limitative of the invention; the invention applies regardless of how far apart the beams are from one another.  
         [0041]    The tracks TR indicated by solid lines in FIG. 4 are those where data have already been written. To write data seamlessly to an unrecorded track following a given recorded track, the write signal controller  15  establishes, at the end of the recorded track in question, an initial location W 1 i for the write beam W 1  that is on the radially innermost side in accordance with data retrieved from the disk using the read beam R. The write signal controller  15  then scans the spiral track TR with the read beam R illustratively in the clockwise direction starting from an initial location Ri so as to read recorded data from the scanned track. Simultaneously, the write signal controller  15  scans the tracks TR with the write beams W 1  through W 3  clockwise starting from the respectively established initial locations W 1 i through W 3 i so as to write data in parallel to the disk.  
         [0042]    The retrieved data above may be constituted by address information held on the track TR, or by other information that already exists on the track in question. That is, the write signal controller  15  illustratively starts writing data from the location designated by an address retrieved by use of the read beam R and scans the track by the amount corresponding to predetermined address information. Alternatively, the write signal controller  15  may retain the data already written to the optical disk  1  and compare the retained data with the data retrieved using the read beam R to determine a write start location and a write end location.  
         [0043]    As data are being written in parallel by scanning the spiral tracks TR with multiple write beams W 1  through W 3 , two complete turns of scan allow the write beams W 1 , W 2  and W 3  to reach the initial locations W 2 i, W 3 i and W 3 f respectively because of the fact that the write beams W 1  through W 3  are two tracks apart from one another.  
         [0044]    At that point, the write signal controller  15  recognizes that the scan has reached the initial location W 1 i based on the data retrieved by the read beam R. Then the write signal controller  15  temporarily stops its write operation.  
         [0045]    When continuously writing data to other tracks TR, not shown, the write signal controller  15  moves the read beam R and write beams W 1  through W 3  collectively in such a manner that the write beam W 1  coincides with a new write start location, and resumes the scan. Illustratively, if data are to be written to tracks radially outside of the location W 3 f, the write signal controller  15  moves the read beam R and write beams W 1  through W 3  collectively so that read beam R and write beam W 1  reach the initial location W 3 i and the location W 3 f respectively. The tracks are then scanned with these beams in the clockwise direction.  
         [0046]    As described, the disk recording apparatus  30  according to the invention writes data in parallel to the optical disk  1  with a plurality of beams by having the scanning locations of the write beams W 1  through W 3  determined based on the data read by the read beam R. This structure makes it possible to record data to the optical disk  1  in nonoverlapping and contiguous fashion between storage regions, whereby high-density data recording is accomplished.  
         [0047]    Although the disk recording apparatus  30  of the invention was described above as writing data to the storage medium composed of the optical disk  1 , this is not limitative of the invention. Alternatively, the storage medium may be the magneto-optical disk as well as the phase-change recording type optical disk and other diverse storage media having tracks TR to which data may be written by scanning operation of the optical pickup  5 .  
         [0048]    As many apparently different embodiments of this invention may be made without departing from the spirit and scope thereof, it is to be understood that the invention is not limited to the specific embodiments thereof except as defined in the appended claims.