INFORMATION RECORDING AND REPRODUCING APPARATUS

Abstract: In an information recording and reproducing apparatus using a disc-shaped information recording medium having a plurality of recording tracks, each of which recording tracks is divided into a plurality of sectors, to record and reproduce information on and from the information recording medium on a sector-by-sector basis, when a target sector (S n ) is detected to be a defective sector whose address can not be reproduced, in the first place, a reference sector (S n-k ), which is positioned preceding the defective target sector and whose address can be reproduced, is detected. Then, a rotational latency time from the detected reference sector (S n-k ) to the defective target sector (S n ) is measured by using: (l) a time measuring circuit (l3) for measuring the rotational latency time per se; or (2) a counter circuit (l4) for counting the number of a sector mark or sector marks (ll) which indicate the presence of an associated sector or sectors and which are detected during the rotational latency time, so that the defective target sector (S n ) may be taken to be a normally detected target sector whereby information may be recorded and reproduced on and from the defective target sector (S n ), thereby making it possible to perform recording and reproduction of informa­ tion on and from a defective sector whose address can not be reproduced.

Description: BACKGROUND OF THE INVENTION FIELD OF THE INVENTION The present invention relates to an information recording and reproducing apparatus, and more particularly relates to an information recording and reproducing apparatus in which recording and reproduction of information are performed on and from a disc-shaped information recording medium having a plurality of recording tracks, each of which recording tracks is divided into a plurality of sectors, and the information recording and reproduction are effected on a sector-by-sector basis. DESCRIPTION OF THE RELATED ART When performing recording and reproduction of information on and from a disc-shaped information recording medium on a sector-by-sector basis, sometimes there is encountered a defective sector whose address can not be reproduced due to a defect existing in the information recording medium, etc. A method of recording and reproducing information on and from such a defective sector in a conventional information recording and reproducing apparatus is disclosed, for example, in Japanese Patent Unexamined Publication No. 59-154654. That is, when it is impossible to reproduce a track address of a target sector, on and from which information is to be recorded and reproduced, but it is possible to identify only a sector address of the target sector by the coincidence detection, by utilizing the result of detection of the respective track addresses of n sectors positioned preceding the target sector, it is possible to identify the track address of the defective target sector and thereby to perform recording and reproduction of information on and from the defective target sector, even when its track address can not be reproduced. In such a conventional method, however, it is impossible to perform information recording and reproducing on and from a target sector, when not only a track address but also a sector address of the target sector can not be reproduced. From JP-A-61-17271 is known an optical disk device for recording and reproducing information on and from an disk-shaped optical information recording medium having a plurality of recording tracks. Under normal circumstances when the address area is without a defect, a SYNC code detection signal is produced from a synchronisation pattern recorded at a leading part of the address field of a respective recording sector, and from this SYNC code detection signal is derived a sector format control signal for controlling the reproduction of the recording sector. On the other hand, if the address area of the target sector is defective and the SYNC code detection signal cannot be produced in this way, a substitutive signal is produced from the SYNC code detection signal of the previous sector by simply delaying the same and using it to derive therefrom the sector format control signal for the defective sector. However, because the substitutive signal from which the sector format control signal is obtained is formed by delaying the SYNC code detection signal from the address field of the reference sector for the same constant period of time for all sectors, the sector format control signal for the defective sector is not related with the address data of the reference sector, which is a drawback, especially when the information recording and reproducing apparatus uses a recording format in which the time intervalls of detecting the SYNC signals are not constant for all tracks. Further, from EP-A-0 147 065 is known a recording and reproducing apparatus for a disk-shaped optical recording medium having a spiral guide track and including a single index field and a plurality of sectors. In this known apparatus a counter is reset by an index mark signal detected from said index field and at the same time the counter counts a sector mark signal detected from the address field of each of the respective sectors. When, as a result of a failure, an address cannot be detected from a target sector, the output signal of the counter is used to derive therefrom a sector control signal to perform recording and reproducing operations from the defective address target sector. In this known apparatus it is necessary for proper operation that the index mark always is detected properly to reset the counter and recording or reproducing cannot be carried out from a defective address target sector if the sector marks cannot be detected properly from each sector. SUMMARY OF THE INVENTION Therefore, it is an object of the present invention to eliminate the disadvantages of the prior art devices. Especially, it is an object of the present invention to provide an information recording and reproducing apparatus in which information recording and reproducing can be achieved on and from a target sector even when not only the track address but also the sector address of the target sector cannot be reproduced. According to the present invention there is provided an information recording and reproducing apparatus using a disk-shaped information recording medium having a plurality of recording tracks, each of which recording tracks is divided into a plurality of sectors, each of said sectors being composed of a sector ID field containing address information and a data field in which data are recorded, so that information is recorded and reproduced on and from said sectors, said apparatus comprising means for detecting a sector, whose address can not be reproduced, to be a defective sector; means for detecting a sector, whose address can be reproduced and which is positioned preceding a target sector on and from which information is to be recorded and reproduced, to be a reference sector; means for producing measurement data determining the rotational latency time from said detected reference sector to said target sector; and means for measuring said rotational latency time from said detected reference sector to said target sector, on the basis of said measurement data; whereby, when a target sector is detected to be a defective sector, said reference sector is detected first and then said rotational latency time from said detected reference sector to said defective target sector is used for effecting recording and reproduction of information on and from said defective target sector. In the information recording and reproducing apparatus of the present invention, when a target sector, on and from which information is recorded and reproduced, is detected to be a defective sector whose address can not be reproduced, in the first place, a reference sector, which is positioned preceding the target sector and whose address can be reproduced, is detected. Then, a rotational latency time from the reference sector to the target sector is measured by using a time measuring circuit or by using a counter circuit for counting the number of sector marks which are detected from respective sectors, whereby information is recorded and reproduced on and from the defective target sector whose address can not be reproduced. The above and other objects and features of this invention will become more apparent from the description of the embodiments of this invention given hereinafter in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a block diagram showing the structure of the information recording and reproducing apparatus of an embodiment of the present invention; Fig. 2 is an explanatory diagram for explaining the structure of one track; Fig. 3 is a flowchart for explaining the operations of recording and reproducing information on and from a defective sector; Figs. 4A and 4B are block diagrams each thereof showing an example of the rotational latency time measuring circuit 5; and Fig. 5 is a waveform diagram showing the waveforms of signals appearing at various portions of the rotational latency time measuring circuit 5 when it is in operation. DESCRIPTION OF PREFERRED EMBODIMENTS Referring to the drawings, the embodiments of the present invention will be described hereinafter in more detail. Fig. 1 is a block diagram showing the information recording and reproducing apparatus of an embodiment of the present invention. In Fig. 1, the information recording and reproducing apparatus of this embodiment includes a main control circuit 2 for controlling the whole information recording and reproducing apparatus in accordance with a device command signal 100 sent from a host computer 1, a sector detection circuit 4 for detecting address information, which is coincident with a retrieval sector address signal 102 set by the main control circuit 2, in a reproduced signal 101 sent from a drive unit 3 and outputting a detection signal 107, a rotational latency time measuring circuit 5 for measuring a rotational latency time from a reference sector to a target sector on the basis of measurement data 103 sent from the main control circuit 2, an information recording circuit 6 for modulating recording information 104 supplied from the host computer 1 and supplying a recording signal 105 produced by the modulation to the drive unit 3, an information reproducing circuit 7 for demodulating data contained in the reproduced signal 101 sent from the drive unit 3 and supplying reproduced information 106 obtained by the demodulation to the host computer 1, a starting circuit 8 for supplying a start signal 109 to the information recording circuit 6 or the information reproducing circuit 7 in accordance with the detection signal 107 supplied from the sector detection circuit 4 or a substitutional detection signal 108 supplied from the rotational latency time measuring circuit 5, respectively. Fig. 2 shows the structure of each track in an information recording medium used in this embodiment. As shown in Fig. 2(a), each track is equally divided into n sectors ranging from a sector S₁ to a sector S n , and each sector is composed of a sector identifier (ID) field 9 and a data field 10. Further, as shown in Fig. 2(b), the sector ID field 9 is composed of a sector mark 11, which shows the beginning end of a sector in common with all the sectors, and an address portion 12 containing address information which includes a track address and a sector address and which is peculiar to each sector. In accordance with the flowchart shown in Fig. 3, the operation of the information recording and reproducing apparatus of the embodiment of the present invention having the above-described structure will be explained hereunder. (A) Upon reception of the device command signal 100 from the host computer 1, the main control circuit 2 performs interpretation of the device command signal 100 and outputs a drive command signal 110 for instructing the drive unit 3 to execute a seek operation for seeking a track which contains a target sector. (B) When the drive unit 3 detects abnormality during the execution of the seek operation, the main control circuit 2 receives a drive status signal 111, which is outputted from the drive unit 3 and indicates abnormal termination of the seek operation, and sends sense information 112 to the host computer 1 to thereby terminate the execution of the command. (C) When the seek operation is normally terminated, the drive unit 3 confirms an associated track address and sends a drive status signal 111, which indicates normal termination of the seek operation, to the main control circuit 2. In order to detect a target sector on and from which information is to be recorded and reproduced, the main control circuit 2 sets a target sector address as a retrieval sector address signal 102 and sends the retrieval sector address signal 102 and an enable signal 113 to the sector detection circuit 4 and to the starting circuit 8, respectively. (D) The sector detection circuit 4 detects address information contained in a reproduced signal 101 sent from the drive unit 3 and performs coincidence detection between the detected address information and the retrieval sector address signal 102. If the target sector is detected by the coincidence between the detected address information and the retrieval sector address signal 102, the sector detection circuit 4 sends a detection signal 107 to the starting circuit 8. (E) If the target sector is not detected within a maximum rotational latency time, the main control circuit 2 stops sending the enable signal 113 to the starting circuit 8, takes a sector positioned immediately before the target sector on the disk as a reference sector, sets the address of the reference sector as a new retrieval sector address signal 102, and sends the new retrieval sector address signal 102 to the sector detection circuit 4. (F) The sector detection circuit 4 detects address information contained in the reproduced signal 101 sent from the drive unit 3, and performs coincidence detection between the detected address information and the new retrieval sector address signal 102. (G) If the reference sector is not detected within the maximum rotational latency time, the main control circuit 2 takes a sector positioned immediately before the current reference sector on the disk as a new reference sector, sets the address of the new reference sector as a further new retrieval sector address signal 102, and sends the further new retrieval sector address signal 102 to the sector detection circuit 4. (H) If the sector detection circuit 4 detects the reference sector, it sends a detection signal 107 to the main control circuit 2. The main control circuit 2 sends an enable signal 113 to the starting circuit 8, and at the same time it sends measurement data 103, which correspond to a rotational latency time from the detected reference sector to the target sector, to the rotational latency time measuring circuit 5 and causes the circuit 5 to start its operation. Upon, completion of the measurement of the rotational latency time given by the measurement data 103, the rotational latency time measuring circuit 5 takes the target sector to have been detected and sends a substitutional detection signal 108 to the starting circuit 8 in place of a detection signal 107. (I) Upon reception of the detection signal 107 sent from the sector detection circuit 4 in the operation of the above paragraph (D), or the substitutional detection signal 108 sent from the rotational latency time measuring circuit 5 in the operation of the above paragraph (H), the starting circuit 8 outputs a start signal 109 which is sent to the information recording circuit 6 or the information reproducing circuit 7 in accordance with the content of the enable signal 113 sent from the main control circuit 2. In an information recording operation, the information recording circuit 6 modulates recording information 104 sent from the host computer 1 and sends a thus produced recording signal 105 to the drive unit 3 to be recorded on the disk therein, thereby completing the execution of a device command 100. While, in an information reproducing operation, the information reproducing circuit 7 detects and demodulates data contained in the reproduced signal 101 sent from the drive unit 3 and sends reproduced information 106 thus produced to the host computer 1, thereby completing the execution of a device command 100. Next, with respect to the operation of the rotational latency time measurement performed by the rotational latency time measuring circuit 5 in this embodiment, two methods therefor will be described with reference to the block diagrams of Figs. 4A and 4B and the signal waveform diagram of Fig. 5. Fig. 5(a) shows the reproduced signal 101 outputted from the drive unit 3 within a time period from a reference sector S n-k , which precedes a target sector S n by k sectors, to the target sector S n . In Fig. 5(a), symbols ID and DF represent a sector ID field 9 and a data field 10 which are comprised in each sector, respectively. Fig. 5(b) shows the detection signal 107 outputted from the sector detection circuit 4. In Fig. 5(b), reference numeral 116 designates a detection signal detected from the reference sector S n-k , and reference numeral 117 indicates the timing of a detection signal to be detected from the target sector S n , if the target sector S n is not a defective sector. Fig. 5(c) shows sector marks 11 (SM₁, SM₂, ..., SM k-1 , SM k ) which are detected by being discriminated from the reproduced signal 101 at the beginning end portions of the sector ID fields 9 of the respective sectors ranging from the sector S n-k+1 , which follows the reference sector S n-k , to the target sector S n . A first one of the two methods is to measure the rotational latency time by using a time measuring circuit 13 as shown in Fig. 4A. In this method, the measurement data 103 outputted from the main control circuit 2 is a rotational latency time per se from the reference sector to the target sector. For example, as shown in Fig. 5(a), when the reference sector S n-k is detected k sectors preceding the target sector S n , the measurement data 103 are given by k·T s sec, where T s represents one sector time length in seconds. the operation of the rotational latency time measurement is started by a process such that the sector detection circuit 4 sends the detection signal 116 shown in Fig. 5(b) to the main control circuit 2 upon its detection of the reference sector S n-k , and, in response thereto, the main control circuit 2 supplies the data of k·T s sec to the time measuring circuit 13 shown in Fig. 4A as the measurement data 103. As the operation of the time measuring circuit 13 is started by the application of the measurement data 103 thereto, the time measuring circuit 13 measures the time indicated by the measurement data 103 by using a clock signal 114 and generates a substitutional detection signal 108 in place of a detection signal 117 shown by a broken line in Fig. 5(b), upon completion of the time measuring operation thereof. While, in a second method, the rotational latency time is measured by using a counter circuit 14 as shown in Fig. 4B. In this method, as a sector mark 11 shown in Fig. 5(c), which is format-recorded at the beginning end of each sector ID field 9 (as shown in Fig. 2(b)), is detected by being discriminated from the reproduced signal 101, the number of the sector marks 11 detected during the rotational latency time from the reference sector to the target sector is applied to the counter circuit 14 as the measurement data 103. For example, when the reference sector S n-k , is detected k sectors preceding the target sector S n , as shown in Fig. 5(a), the total number k of the sector marks SM i (i = 1 to k ) detected in the sector ID fields 9 of the respective sectors ranging from the sector S n-k+1 to the target sector S n , as shown in Fig. 5(c), is applied to the counter circuit 14 as the measurement data 103. As the operation of the counter circuit 14 is started by the application thereto of the data k as the measurement data 103, the counter circuit 14 counts k sector marks 11 and generates a substitutional detection signal 108 in place of a detection signal 117 shown by a broken line in Fig. 5(b), upon completion of the counting operation thereof, only with a time delay corresponding to the rotational latency time for an address portion 12 of a sector ID field 9 shown in Fig. 2(b). Further, the main control circuit 2 in this embodiment may be realized by using a general purpose microprocessor. The microprocessor may include the above-mentioned time measuring circuit or counter circuit. Alternatively, it is possible to realize the function of the rotational latency time measuring circuit 5 in the microprocessor by counting the sector marks 11 shown in Fig. 5(c) by using software in the microprocessor. As described above, in the information recording and reproducing apparatus according to the present invention, when a target sector, on and from which information is to be recorded and reproduced, is detected to be a defective sector whose address can not be reproduced, in the first place, a sector, which is positioned preceding the defective target sector and whose address can be reproduced, is detected as a reference sector. Then, by measuring the rotational latency time from the detected reference sector to the defective target sector by using a time measuring circuit or a counter circuit for counting the number of sector marks 11 detected in the respective sectors, it is possible to effect recording and reproduction of information on and from the defective target sector, taking as if the target sector can be detected. Accordingly, with the information recording and reproducing apparatus according to the present invention, it is possible to record and reproduce information on and from a sector even when the sector is defective. Thus, the information recording and reproducing apparatus of the present information has a remarkable advantage in practical use.

Claims: An information recording and reproducing apparatus using a disc-shaped information recording medium having a plurality of recording tracks, each of which recording tracks is divided into a plurality of sectors (S₁ to S n ), each of said sectors being composed of a sector ID field (9) containing address information and a data field (10) in which data are recorded, so that information is recorded and reproduced on and from said sectors, said apparatus comprising: means (4) for detecting a sector, whose address can not be reproduced, to be a defective sector; means (4) for detecting a sector, whose address can be reproduced and which is positioned preceding a target sector (S n ) on and from which information is to be recorded and reproduced, to be a reference sector (S n-k ); characterized by means (2) for producing measurement data (103) determining the rotational latency time from said detected reference sector (S n-k ) to said target sector (S n ); and means (5) for measuring said rotational latency time from said detected reference sector (S n-k ) to said target sector (S n ), on the basis of said measurement data (103); whereby, when a target sector (S n ) is detected to be a defective sector, said reference sector (S n-k ) is detected first and then said rotational latency time from said detected reference sector (S n-k ) to said defective target sector (S n ) is used for effecting recording and reproduction of information on and from said defective target sector (S n ). An information recording and reproducing apparatus according to Claim 1, in which the rotational latency time is measured by using a time measuring circuit (13). An information recording and reproducing apparatus according to Claim 2, in which said time measuring circuit (13) for measuring the rotational latency time is incorporated in a microprocessor. An information recording and reproducing apparatus according to Claim 1, in which said sector ID field (9) includes a sector mark (11) for indicating the presence of said associated sector ID field (9) so that, as said sector mark (11) is detected during the rotational latency time, the rotational latency time is measured by using a counter circuit (14) for counting the number of said detected sector mark or sector marks (11). An information recording and reproducing apparatus according to Claim 4, in which said counter circuit (14) for measuring the rotational latency time is incorporated in a microprocessor. An information recording and reproducing apparatus according to anyone of Claims 1 to 5, in which only a sector, whose address can be reproduced and which is positioned one or two sectors preceding a target sector (S n ) on said disc-shaped information recording medium, is detected to be a reference sector (S n-k ). An information recording and reproducing apparatus according to anyone of Claims 1 to 6, in which, only when a target sector (S n ) is detected to be a defective sector at the time of reproducing information, a reference sector (S n-k ) is detected and then the rotational latency time from said detected reference sector (S n-k ) to said defective target sector (S n ) is measured, thereby reproducing information from said defective target sector.

Inventors: FUKUSHIMA, YOSHIHISA, ICHINOSE, MAKOTO, KUROKI, YUZURU, SATOH, ISAO, TAKAGI, YUUJI
Applicants: MATSUSHITA ELECTRIC INDUSTRIAL CO., LTD.
Application year: 1987
Main classification: G11B20
IPC codes: G11B20, G11B27