Abstract:
For protecting the recording from shifting in the position, by conducting sync detection, correctly, from land pre pits, in an optical type recording disc, even if sync pattern errors, in more detail, synchronization is conducted on a recording circuit, with certainty, even if an even sync pattern erroneously changes into an odd sync pattern. When the even sync pattern is detected from an odd sync pattern detection window, a sync lock flag is turned into a condition of unlock. When the sync lock flag continues a lock condition for 16 sectors, the synchronization is carried out on a detection cycle counter and a recording cycle counter.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a recording apparatus for recording on a DVD-R or a DVD-RW, for example, and in particular, it relates to a recording apparatus, while reproducing land pre pit information, which is recorded on a land track in advance, for indicating address information on the disk, for recording on the disk in accordance therewith. 
   2. Description of the Related Art 
   Conventionally, reproduction of the land pre pits is performed in the following manner, in particular, on those that are formed on the DVD-R and/or DVD-RW. First of all, a light beam is irradiated upon the groove track, on which information is recorded, thereby obtaining a wobble signal from a reflection light thereof, through so-called a push-pull method. This wobble signal is then compared to a predetermined threshold signal, so as to extract a signal therefrom, exceeding the threshold signal, thereby obtaining the land pre pit signals, which are superimposed on the wobble signal. 
   Next, when counting five (5) cycle periods of the wobble signal where no land pre pit can detected, on the land pre pit signal, three (3) cycles of the wobble signals are counted just thereafter, and then a gate signal is outputted, for allowing detection of the land pre pit information within that period. When the land pre pit is detected during those three (3) cycles, eight (8) cycles of the wobble signals are counted up starting from the timing of detection of the first land pre pit upon a recording reference clock. Thereafter, only the land prepit signal is adopted, which appears in the front three (3) cycles of those eight (8) cycles of the wobble signals. 
   When a counter for counting the eight (8) cycles of wobble signals counts, but under erroneous timing, it comes to be inconsistent with the three (3) cycles of wobble signals for allowing the detection, in the timing thereof, and then the counter for the eight (8) cycles of wobble signals is preset. Conventionally, the decode processing is conducted on the land pre pit information, in such the manner as is mentioned, for example, in Japanese Patent Laying-Open No. Hei 10-340536 (1998) &lt;JP-A 10-340536&gt;. 
   SUMMARY OF THE INVENTION 
   According to the standards of the DVD-R and DVD-RW, the land pre pit signal has a rule of appearing for every eight (8) wobble cycles, as was mentioned in the above, however in more detail, the land pre pit signal appears in the front-side three (3) cycles of a first half of eight (8) wobble cycles, or the front-side three (3) cycles of a second half of eight (8) wobble cycles, among the continuous 16 wobble cycles. Herein, the front-side 3 cycles of the first 8 cycles are called by “even”, while the front-side 3 cycles of the second 8 cycles are called by “odd”. Also, 16×13 wobble cycles are called by a “sector”, and a land pre pit information of a sector synchronization signal appears in either the even or the odd side of the top 16 wobble cycles of the sector. 
     FIG. 7  shows a chart for showing the meanings of pre pit patterns of the front-side 3 cycles and the respective pre pit patterns thereof, among the wobbles of 8 cycles. Thus, “111” means an even sync pattern recorded at the “even” position, “110” an odd sync pattern recorded at the “odd” position, “101” data of a binary code “1”, and “100” data of a binary code “0”, respectively. As is shown herein, the land pre pit information is “111”, when it has the sync signal in the even side, while it is “110” when it has the sync signal in the “odd” side. Here, for the purpose of detecting the land pre pit information, correctly, from the signals having noises thereon, it is common to conduct the processing thereon, such as, the filtering, the slicing, etc., when a disk recording apparatus reads those signals. However, disappearing of pulses may occur during the steps of conducting such the processing thereon. 
   Namely, it may sometimes come to be “110” when the pulse falls down at the third cycle of the sync signal “111” in the even side, due to the factors, such as, the noises, etc., for example, and then it is the same to the sync signal in the odd side. Accordingly, the recording apparatus erroneously recognizes to be “odd” in the position thereof, in spite of the “even” position on the disk. An object according to the present invention, therefore, is to protect the recording apparatus from such the shifting in the position for starting the recording. 
   The object mentioned above, according to the present invention, can be accomplished by provision of a detection cycle counter for counting 16×13 wobble cycles, wherein the detection cycle counter is synchronized when a sync signal of land pre pit information is detected, and at the same time a sync lock flag is set. When detecting the sync pattern indicative of an even, for example, a sync lock flag keeps the condition of being set if the sync pattern indicative of the even is detected after 16×13n (n: a natural number) wobble cycles, or if the sync pattern indicative of the odd is detected after 16×13n+1 wobble cycles, next, and also in a case where the sync pattern of the even or odd is detected at a timing different from the mentioned above, synchronizing is made on the detection cycle counter, as well as, resetting the sync lock flag at the same time. Also, in a case where it cannot be detected for a time period being equal or longer than 16×13m+1 (m: a natural number) wobble cycles, the sync lock flag is reset. And, when the sync lock flag continues the condition of being set for a predetermined time period, a recording timing producing cycle counter, which is provided separately, is synchronized by means of the detection cycle counter. 
   In more details thereof, according to the present invention, for accomplishing the object mentioned above, there is provided an optical disk recording apparatus, for recording a digital signal on a recordable optical disk, wherein a first sync pattern recorded in a phase  1  and a second sync pattern recorded in a phase  2  are recorded at positions, having a predetermined relationship in the phases the thereof, on a track wobbled at a constant cycle, comprising: a detection window producing means for said phase  1 ; a detection window producing means for said phase  2 ; a sync lock flag producing means for producing a sync lock flag indicative of a condition that synchronization is locked; and a recording timing producing means for producing a recording timing onto said optical disc, wherein said sync lock flag producing means produces the sync lock flag indicative of the condition that the synchronization is locked, when the first sync pattern is detected in the phase  1  or when the second sync pattern is detected in the phase  2 , while producing a sync lock flag indicative of a condition that the synchronization is unlocked when the first sync pattern is detected in the phase  2 , and said recording timing producing means conducts the synchronization on said sync pattern when the sync lock flags are detected, continuously, for a predetermined time period, indicating the condition that the synchronization is locked. 

   
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
       FIG. 1  shows an optical disk recording apparatus, according to one embodiment of the present invention; 
       FIG. 2  shows a time chart for an example of land pre pit signals, which will be treated within the present invention; 
       FIG. 3  also shows a time chart for an example of the land pre pit signals, which will be treated within the present invention; 
       FIG. 4  shows a time chart for an example of the land pre pit signals, which will be treated within the present invention; 
       FIG. 5  shows a time chart for an example of the land pre pit signals, which will be treated within the present invention; 
       FIG. 6  shows a data format of the land pre pit signal upon basis of the DVD-R standard; 
       FIG. 7  also shows a data format of the land pre pit signal upon basis of the DVD-R standard; 
       FIG. 8  shows a time chart of a sync detection cycle counter, according to the embodiment; 
       FIG. 9  also shows a time chart of a sync detection cycle counter, according to the embodiment; 
       FIG. 10  shows a time chart of a recording cycle counter, according to the embodiment; 
       FIG. 11  shows an optical disk recording apparatus, according to other embodiment of the present invention; 
       FIG. 12  shows an optical disk recording apparatus, according to further other embodiment of the present invention; and 
       FIG. 13  also shows an optical disk recording apparatus, according to further other embodiment of the present invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Hereinafter, embodiments according to the present invention will be fully explained by referring to the attached drawings. Herein,  FIG. 1  is a block diagram of a disk recording apparatus according to the present invention. In this  FIG. 1 , a reference numeral  101  is a means for detecting a pre pit formed on a land track of a disk,  102  a means for detecting an even sync pattern from the pre pit detected, and  103  a means for detecting an odd sync pattern from the pre pit detected. 
   The even sync pattern detection means  102  detects the pattern “111”, and the odd sync pattern detection means  103  detects the pattern “110”, respectively. A reference numeral  104  depicts an detection cycle counter, turning one (1) round by 16×13 wobbles, and it is synchronized with a timing, at which the respective patterns should be generated, when the sync signals are detected by the even sync pattern detection means  102  and the odd sync pattern detection means  103 , respectively. 
   A reference numeral  105  depicts a detection window, which is produced by the detection cycle counter  104  and is opened at a position where the odd sync pattern should be generated. A reference numeral  106  depicts another detection window, which is produced by the detection cycle counter  104  and is opened at a position where the even sync pattern should be generated. A reference numeral  107  depicts an even/odd un-detect signal generation means, and it generates an even/odd un-detect signal when the detection cycle counter  104  counts up for a predetermined period, but not being synchronized with upon detection of the even/odd sync pattern. A un-detect number counter  108  counts the number of times when the even/odd un-detect signals are generated, continuously, but without detecting the even/odd sync pattern. 
   A reference numeral  109  is a sync un-detect number count setting value, and it produces a sync lock flag reset signal when the even/odd sync pattern un-detect continues and reaches to the number of times, which is set in advance. A sync lock flag  110  is reset by any one of the sync lock flag reset signal from  109 , the even sync pattern detection signal from  105 , which is gated through the odd window, and the odd sync pattern detection signal from  106 , which is gated through the even window. 
   A gate circuit  116  is opened in a case where the sync lock flag  110  is reset into the unlock condition. When the gate circuit  116  is opened, the sync lock flag  110  is set into the lock condition, by either one of the even sync pattern detection signal, which is detected by the even sync pattern detection means, or the odd sync pattern detection signal, which is detected by the odd sync pattern detection means. 
   In this manner, the sync lock flag  110  turns into the unlock condition, in any cases where the sync pattern cannot be detected, continuously, for a predetermined time period, when the odd sync pattern is detected at the position where the even sync pattern should be generated, and when the even sync pattern is detected at the position where the odd sync pattern should be generated, and also it turns into the lock condition when the sync pattern is detected under the unlock condition. 
   If the sync lock flag continues to be under the lock condition for a time period determined by a sync lock flag check region production means  111 , a recording cycle counter  112  for producing a recording timing is synchronized with the detection cycle counter. An encoder  113  conducts the encode processing in accordance with the DVD format, at the timing produced by the recording cycle counter. After being waveform shaped in a laser diode driver  114 , the encoded signal drives a laser diode  115 . 
   As was mentioned in the above, according to the present embodiment, even if the last digit is lost from the even sync pattern, i.e., “111”, then it comes to be the odd sync pattern, i.e., “110”, since it is protected by means of the sync flag; therefore the synchronization can be carried out on the recording timing, with stability. 
   Next, explanation will be made on examples of the land pre pit signals, to be used in the present invention, by referring to  FIGS. 2 ,  3 ,  4  and  5 . All of those  FIGS. 2 ,  3 ,  4  and  5  are in accordance with the standard of the land pre pit of the DVD-R/RW shown in  FIGS. 6 and 7 . 
   In  FIG. 2 , the “even sync pattern” lies at the position of “even”, i.e., at the head of  201 , and at the position of “even” following thereto lies “0 (binary)” data. On  202 - 206 , the data “0000000000 (binary)” lies at the position of “even”. On  207 , “1 (binary)” lies at the first “even” position, and at the “even” position following thereto lies “even sync pattern”. In the similar manner, on  208 - 210 , “000100 (binary)” lies at the “even” position. 
   Comparing this to  FIG. 6 , it can be seen that a relative address “0000” lies after the “sync pattern” of  201 , and that a relative address “0001” after the sync pattern of  207 . 
   In  FIG. 2  is shown a case where all the land pre pits lie at the positions of “even”, however according to the DVD standard, it is determined to use the “odd” position, so that the land pre pits are not adjacent to each other on the neighboring tracks. An example, where data is also recorded at the “odd” position, is shown in  FIG. 3 . Comparing this to  FIGS. 6 and 7 , it can be seen that the relative address “0000” and the data “00000001” lie after the “sync pattern” of  301 , and the relative address “0001” lies after the “sync pattern” of  307 . In the example shown in  FIG. 3 , although the “odd” sync pattern is used on  307 , the data at the “odd” position on  302 ,  304  and  305  are same to the data shown in  FIG. 2 . 
   Next, an example is shown in  FIG. 4 , where the sync pattern is erroneously recognized, due to such as a result of filtering process, etc. In the example shown in  FIG. 4 , the last pulse is lost on the even sync pattern “111” at the position  407  where the even sync patter is recorded, thereby changing into the odd sync pattern, i.e., “110”. Accordingly, if recognizing the position where the odd sync pattern is detected to be the position of the “odd”, there occurs shifting in the position recognition. 
   In the embodiment shown in  FIG. 1 , the detection cycle counter is synchronized with the even sync pattern of  401 , and then the windows are produced at the position where the even sync patter should be generated and the position where the odd sync pattern should be generated. In  FIG. 4 , since the odd sync pattern is detected within the window at the position where the even sync patter should be generated, then the even sync pattern is in the unlock condition. For this reason, the recording cycle counter is inhibited from being synchronized with the detection cycle counter, and therefore the recording is protected from causing the position shifting therein. 
   Next, an example is shown in  FIG. 5 , where a pseudo sync pattern is produced, due to mixture of noises, etc. In the example shown in  FIG. 5 , “1” rises up at the last bit of the odd sync pattern “110”, i.e., at the position  507  where the odd sync patter is recorded, due to noises, then it is erroneously recognized to be the even sync pattern “111”. Accordingly, if recognizing the position where the even sync pattern is detected to be the position of the “even”, there occurs shifting in the position recognition. In the embodiment shown in  FIG. 1 , since the even sync pattern is detected within the window at the position where the odd sync pattern should be generated, the sync lock flag is in the unlock condition. For this reason, the recording cycle counter is inhibited from being synchronized with the detection cycle counter, and therefore the recording can be protected from being shifted in the position thereof. 
   Next, operation of the detection sync counter will be explained by referring to  FIG. 8 . The horizontal axis in  FIG. 8  indicates a reproduction position while the vertical axis a value of the counter. Being synchronized upon the even sync pattern detection at the left-hand side end in the same figure, the counter value is comes down to zero (0). Then, it counts up the count value by every wobble. After one (1) sector, i.e., at 208 th  wobble (=8 wobbles×2×13), it is the position where the next even sync pattern should be generated. Accordingly, the counter counts up to 207, and it detects the even sync pattern at the position of 208 th  wobble, thereby turning back to zero (0), thereafter conducting the count up, again. Further, the similar processing is carried out when detecting the next odd sync pattern upon the basis of the odd sync pattern detection. 
     FIG. 9  also shows the operation of the detection counter, in a similar manner. The count value comes down to zero (0) at the left-hand side end when detecting the even sync pattern, and thereafter it counts up the count value for every wobble. Since the next sync pattern lies at the “odd” position in  FIG. 9 , 216 th  wobble (=1 sector+8 wobbles) is the position where the next odd sync pattern should be generated. Accordingly, after counting the count value up to 215, it is preset to eight (8). However, when detecting the next even sync pattern upon the basis of the odd sync pattern detection, since 200 th  wobble (=1 sector−8 wobbles) from the odd sync pattern is the position where the next even sync pattern should be generated, therefore the count value is preset to 0 after counting up to 199. 
   Next, explanation will be given on synchronization in the recording cycle counter, by referring to  FIG. 10 . This  FIG. 10  shows the detection condition for each of the sync signal of “even” or “odd” at a unit of sector, and behavior of the sync lock flag for it, as well as, the synchronization operation of the recording cycle counter. 
   In  FIG. 10 , “x” indicates the condition where the odd sync pattern is detected within the even sync pattern detection window, or the condition where the even sync pattern is detected within the odd sync pattern detection window. A mark “Δ” indicates a case where no new sync pattern cannot be detected after passing 208 or 215 wobble cycles. A mark “O” indicates the condition where the even sync pattern is detected within the even sync pattern detection window, or the condition where the odd sync pattern is detected within the odd sync pattern detection window. The “sector No.” indicates the relative address, which was shown in  FIG. 6 , from bit 1  to bit 4 . 
   In  1001 , the sector  15  at the end of the left-hand side is in the “x” condition, and the sync lock flag is in the unlock condition. It comes into the “O” condition at the sector  1 , and then the sync lock flag turns back into the lock condition. Hereinafter, the detection condition continues to be “O” from the sector  0  to the sector  15 , and the sync lock flag continues to be the lock condition. When continuing the lock condition during this time period, the synchronization is carried out on the recording cycle counter. 
   Next, an example of the time period is shown, which is determined by the sync lock flag check region producing means  111  shown in  FIG. 1 . In  1002 , it is in the “x” condition at the sector of the left-hand side end, and then the sync lock flag is in the unlock condition. Also, it is in the “O” condition at the sector  1 , and then the sync lock flag turns back to the lock condition. The “Δ” condition continues eight (8) times from the sector  4 , and at the sector  11 , the sync lock flag turns into the unlock condition. 
   Herein is shown a case where the setting number of times is eight (8), in the operation of producing the sync lock flag reset signal when the even/odd sync pattern un-detect shown in  FIG. 1  reaches to a number of times that is set in advance. In this case, since the lock condition does not continue for the time period from the sector  0  to the sector  15 , therefore no synchronization is carried out on the recording cycle counter. In the above, the detailed operation was explained on the recording cycle counter. 
   However, although it is indicated that the synchronization may be conducted by any number of times, if the lock condition continues for the time period between the sector  0  to the sector  15 , in the present example, but it is also possible that the synchronization is conducted only one (1) time, i.e., at the first time among those when the conditions are satisfied, during the time period, starting from beginning read-out of the land pre pits after moving a pick until the recording. Limiting the number of times of synchronization to only one (1) time enables to reduce the possibility of shifting due to the erroneous sync patter, much more. 
   Next, explanation will be given on other embodiment according to the present invention.  FIG. 11  is a block diagram of the disc recording apparatus according to the present invention. In  FIG. 11 , the structures are same to those shown in  FIG. 1 , but except for  1101  and  1102 . The reference numeral  1101  indicates an odd sync pattern counter, and it counts up the number of the odd sync patterns within the region, which is determined by the sync lock flag check region production means  111 , so as to resets the sync lock flag  1102  when it exceeds a predetermined number, thereby bringing it into the unlock condition. Other operations thereof are same to those of the disc recording apparatus shown in  FIG. 1 . The present embodiment utilizes the fact that, inherently, the odd sync pattern is used for the purpose of shifting the position thereof if the even sync patterns are adjacent with each other on the neighboring tracks, and therefore it will never exceeds a certain ratio. According to the present embodiment, it is possible to enhance the protection from generating the position shifting when recording. 
   Next, explanation will be given on further other embodiment according to the present invention.  FIG. 12  is a block diagram of the disc recording apparatus according to the present invention. In  FIG. 12 , the structures are same to those shown in  FIG. 11 , but except for  1201 ,  1202  and  1203 . The reference numeral  1201  indicates a sync detection window; thus, a window to be opened at the position where the even sync pattern or the odd sync pattern should be generated. The detection cycle counter  1202  may be synchronized with, also via the sync pattern not passing through the sync detection window  1201 , in the case where the sync lock flag  1102  is in the unlock condition, however in the case where the sync lock flag is in the lock condition, the synchronization is carried out on the detection cycle counter  1202  only when the sync pattern detection is conducted within the sync detection window  1201 . However, this sync detection window  1201  is produced by means of detection cycle counter  1202 . Also, an un-detect number counter  1203  may be reset by the sync pattern that does not passing through the sync detection window  1201 , in the case where the sync lock flag  1102  is in the unlock condition, however in the case where the sync lock flag is in the lock condition, it is reset only in the case where the sync pattern detection is conducted within the sync detection window  1201 . Other operations are similar to those of the disc recording apparatus shown in  FIG. 11 . According to the present embodiment, since the detection cycle counter  1202  does not conduct the synchronization on the pseudo sync pattern during when conducting the sync lock, even in the case where the pseudo sync patterns are generated due to noises at the land pre pits indicating the data bits, therefore no such the position shift occurs in the recording cycle counter, thereby achieving the recording at the correct position. 
   Next, explanation will be given on further other embodiment according to the present invention.  FIG. 13  is a block diagram of the disc recording apparatus according to the present invention. In  FIG. 13 , the structures are same to those shown in  FIG. 11 , but except for  1301 ,  1302  and  1303 . The reference numeral  1301  indicates a reverse signal of the sync detection window  1201 , and it opens the window at the position where, inherently, the sync signal should be detected. The reverse window  1301  is produced by means of a detection cycle counter  1302 . With the sync pattern, passing through the reverse window  1301  to be detected, a sync lock flag  1303  is reset, and it is in the unlock condition. Accordingly, the recording cycle counter is not synchronized with, even if detecting the sync pattern passing through the reverse window, therefore the synchronization will not occur, erroneously. 
   As was fully explained in the above, according to the present invention, it is possible to protect the recording position from being shifted in the position thereof, if the even sync pattern is erroneously detected to be the odd sync pattern, or if the odd sync pattern is erroneously detected to be the even sync pattern. 
   The present invention may be embodied in other specific forms without departing from the spirit or essential feature or characteristics thereof. The present embodiment(s) is/are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the forgoing description and range of equivalency of the claims are therefore to be embraces therein.