JP3722738B2 - Method of searching for target sector in recording medium and reading apparatus therefor - Google Patents

Description

[0001]
[Technical field to which the invention belongs]
The present invention relates to a method for searching a target sector in a recording medium and a reading device thereof, and more particularly to a searching method and a reading device for reading a target sector of data quickly and accurately.
[0002]
[Prior art]
When an optical disk drive reads a data sector from an optical disk, it first identifies the wrong data sector by checking whether it is the target sector that it is looking for, or whether it is the correct target sector. Pick up and don't decode. However, an error occurs in the ID code in the data sector recorded on the optical disk during the manufacturing process of the optical disk or due to other factors, or the error generated in the ID code of the other data sector becomes the ID code of the target sector. When a problem occurs, the optical disk drive cannot find the target sector in the end, and when decoding starts, it must be found that the target sector is incorrect and must be searched again. Invite Therefore, how to design the optical disc drive so that the target sector can be found quickly and accurately is an important issue.
[0003]
Currently, a method and system for searching for a target sector in a recording medium is a DVD optical disk drive. As shown in FIG. 1, the DVD optical disk drive 1 includes a modulation / demodulation means 11, a data buffer 12, an error correction code decoder 13, and the like. , A descrambling and error detection code confirmation means 14 and an ATAPI device 15 are provided. When the DVD optical disk drive 1 searches for a target sector on the optical disk 10 and executes data reading, the pickup head first performs a long seek on the optical disk 10 and quickly moves the pickup head to the vicinity of the target sector and then short-circuits. The target sector is found by seeking. First, the pickup head reads a data sector in the vicinity of the target and transmits it to the modulation / demodulation means 11 to make a determination. The modulation / demodulation means 11 is immediately based on an ID error detection code (hereinafter referred to as IED) in the data sector, The data sector is verified against the ID, and if the result of the verification is correct, it means that there is no error in the ID code of the data sector, and the pickup head immediately determines the data sector and the target sector based on the ID of the data sector. And starting from the target sector, the data sectors of the optical disk are sequentially stored in the data buffer 12 and an error correction code (hereinafter ECC) data block 16 is accumulated. When formed, as shown in FIG. 1, the ECC data block 16 has internal data other than the main data 161. Royalty code (hereinafter, PI) 162 and outer parity code (hereinafter, PO) and a 163. Thereafter, the ECC data block 16 is transmitted to the ECC decoder 13, and the decoded data and error verification operation are performed to determine whether the read data is accurate and free of errors.
[0004]
However, in the above method of searching for the target sector, there is a possibility that an incorrect target sector is still found or an erroneous data sector is mistaken as an accurate target sector. There are the following two causes.
[0005]
1. As shown in FIG. 2, an error occurs in the ID code of the other data sector on the optical disc. For example, the next of 4CFFFF should be 4D0000, but if it is mistaken for 400000, the ID code of the target sector being searched becomes 400000, and the modulation / demodulation means 11 matches the verification of the ID error detection code. End up. Alternatively, the ID code of the other data sector becomes the ID code of the target sector that is being searched for after the decoding of the ID error detection code. For example, after 4CFFFF should be 4D0000, but 4D0000 is IDIED De After the code, the ID code of the target sector being searched becomes 400000. This misidentifies that it is an accurate ID code.
[0006]
2. As shown in FIG. 3, when an error of 3FFFFF occurs in the ID code of the other data sector on the optical disk, it is as if the ID code of the data sector in the vicinity of the target sector 400000 being searched for, and the ID error detection code (IED) is consistent with the verification. Or, after other data sectors have undergone ID error detection code decoding (IDIED), their IDs are as if they were the ID code 3FFFFF of the data sector near the target sector 400000 that you are looking for, and they are misidentified as an accurate ID code. Resulting in.
[0007]
Therefore, when the ECC data block 16 is transmitted to the ECC decoder 13 and the data is decoded, the decoding is sequentially performed from the PI direction and the PO direction of the ECC data block 16, and the ID of each data sector in the ECC data block 16 is again executed. If the correctness is confirmed and an error is found in the ID code, a new search operation for the target sector must be performed again. This is because in this known method, it is impossible for the modem 11 to verify the correctness of the ID by IED, and it is impossible to completely detect the error of the ID. This is because even if an ID error is discovered later during ECC decoding, a lot of time is again spent in the target sector search. This is necessary for the target sector search in a general DVD optical disc drive. The time is approximately 25 to 80 times as long as decoding with the ECC data block.
[0008]
[Problems to be solved by the invention]
Accordingly, a main object of the present invention is to provide a method for searching for a target sector in a recording medium and a reading apparatus thereof that can accurately search for a target sector in the recording medium and achieve an effect of a quick data reading operation. is there.
[0009]
According to the above object, the target sector search method in the present invention is executed in a recording medium reader comprising modulation / demodulation means, a data buffer, and an error correction code decoder. Search for. The method includes: (a) reading a data sector in the recording medium into a modulation / demodulation means to generate an error correction code data sector having an ID code, an ID error detection code, and an internal parity code; Sending error correction code data sectors to the data buffer and the error correction code decoder, respectively, (b) the error correction code decoder reads an ID error detection code and an internal parity code in the error correction code data sector; The verification is executed on the ID code of the error correction code data sector, and the verification result is transmitted to the modulation / demodulation means. (C) Based on the error verification result, the steps (a) and (b) are repeated. (D) on the recording medium based on an accurate verification result. With finding the target sector that, starting from the target sector, and stored sequentially the data buffer subsequent data sectors, as well as the composition of the ECC data block, performs decoding transmitted to the error correction code decoder, In the step (d), while the error correction code decoder is waiting for the data buffer to transmit the error correction code data block, the modulation / demodulation means continues to receive data sectors from the recording medium. And verifying the ID code by transmitting the corresponding error correction code data sector to the data buffer and the error correction code decoder, respectively, so that the error correction code decoder is transmitted from the data buffer. When the error correction code data block is received, the ID code verification operation is temporarily suspended until the reception is completed, and the error correction code data block is decoded again. As a result, the data can be read quickly and accurately.
[0010]
In addition, an apparatus for performing the above method according to the present invention has an ID code, an ID error detection code, and an internal parity code by receiving a data sector in the recording medium and executing a demodulation operation. Modulation / demodulation means for generating an error correction code data sector, a data buffer that composes an ECC data block by temporarily storing the error correction code data sector transmitted from the modulation / demodulation means, and transmitted from the modulation / demodulation means An error correction code decoder that performs ID code verification for each error correction code data sector and further performs error correction decoding operations for the ECC data block transmitted from the data buffer. And. In addition, the modulation / demodulation means simultaneously transmits the error correction code data sector to the data buffer and the error correction code decoder, and the error correction code decoder verifies the ID code of the error correction code data sector. If the result is accurate, the target sector is found based on the ID code, the recording media reader starts from the target sector, and the subsequent data sectors are sequentially stored in the data buffer, and the ECC data Wait for the composition of the block, send the ECC data block to the error correction code decoder and perform decoding, if not as above, That is, if the verification result is not accurate, The modulation / demodulation means transmits the next error correction code data sector to the data buffer and the error correction code decoder, thereby performing ID code verification again until a data sector with a correct verification result is found. As a result, there is an effect of reading data quickly and accurately.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Reference is first made to what is shown in FIG. This is a schematic circuit block diagram of the preferred embodiment of the present invention. The target sector search method of this embodiment is executed by the recording medium reading means 2 to accurately search the target sector in the recording medium 20. The recording medium reading means 2 reads out the data recorded in the recording medium 20 and transmits it to the main device for reproduction by being a bridge between the recording medium 20 and the main device that reproduces the recording medium 20. It is what is done. Moreover, the recording medium reading means 2 is a DVD optical disk drive in this embodiment, and the recording medium 20 to be accessed is an optical disk (for example, an optical recording medium such as a DVD, VCD or CD). When normal data is recorded on the recording medium 20, the data sector 200 is a basic recording unit and is sequentially stored on a track on the optical disc. As shown in FIG. A code (hereinafter referred to as ID) 201, an ID error detection code (hereinafter referred to as IED) 202, main data 203, an error detection code (EDC / CRC) 204, etc., of which ID 201 is the sector number of the data sector 200 In addition, the IED 202 performs error detection on the ID 201 to prevent an error from occurring during data writing of the ID 201.
[0012]
Refer again to what is shown in FIG. The DVD optical disc drive 2 mainly includes modulation / demodulation means 21, a data buffer 22, an error correction code decoder 23 (hereinafter simply referred to as ECC), and a multiplexer 28. When the DVD optical disc drive 2 searches for certain data in the recording medium 20 and wants to read and reproduce it, the data cannot be read unless the start position (that is, the target sector) of the data is searched first. Therefore, the DVD optical disk drive 2 first performs a long seek, moves the pickup head to the vicinity of the track where the data is stored, and then performs a short seek to search for the target sector at the start position of the data. That is, when the pickup head enters a short seek, the target sector is not found immediately. Normally, the pickup head reaches a certain data sector before the target sector, and then the data sector is an accurate data sector. Then, the target sector is found by estimating and calculating the exact position of the target sector based on the data sector.
[0013]
Therefore, as shown in FIG. 6, the method of the present invention includes the following steps.
[0014]
(a) First [ Step 30 Is read out from the optical disc 20 and transmitted to the modulation / demodulation means 21 at the short seek stage of the DVD optical disc drive 2. continue,〔 Step 31 The modulation / demodulation means 21 demodulates the data sector 200 and generates a corresponding error correction code data sector 210 (hereinafter simply referred to as ECC data sector). Please refer to FIG. In addition to the ID code (hereinafter referred to as ID) 211, the ID error detection code (hereinafter referred to as IED) 212, and the main data 213 existing in the data sector, the ECC data sector 210 includes an internal parity code (for executing horizontal error detection). Hereinafter, PI) 214 and an external parity code (hereinafter referred to as PO) 215 for performing vertical error detection are added. Thereafter, the modulation / demodulation means 21 transmits the ECC data sector 210 to the data buffer 22 and the error correction code decoder 23 via the bus 24, respectively. In addition, the data buffer 22 temporarily stores the ECC data sector 210 transmitted from the modulation / demodulation means 21, accumulates a certain amount of the ECC data sector 210, forms the ECC data block 25, and then stores the ECC data sector 25. The block 25 is transmitted to the ECC decoder 23 for decoding, and as shown in FIGS. 4 and 8, the ECC data block 25 is composed of main data 251 and an internal parity code (hereinafter referred to as a vertical code) formed in the vertical direction. , A simplified PI) 252 and an external parity code (hereinafter simply referred to as PO) 253 formed in the horizontal direction, and a plurality of main data 251 (16 in this embodiment is taken as an example). Of data sectors 200.
[0015]
(b) Continued [ Step 32 ] Is executed. The error correction code decoder 23 (hereinafter, ECC decoder) starts verification of the ID code 211 of the ECC data sector 210. First, the ECC decoder 23 performs decoding on the ECC data block 25 transmitted from the data buffer 22, and so-called decoding refers to the ECC data block 25 having PI 252 and PO 253 in the ECC data block 25. The main data 251 is subjected to vertical and horizontal decoding and error detection, respectively. Therefore, in the known technique, when the ECC data block 25 in the data buffer 22 is not formed, the ECC decoder 23 is always in an idle state and is not efficiently used. Therefore, the present invention uses the characteristic that the idle time in the ECC decoder 23 and the demodulation method of the modulation / demodulation means 21 are conveniently the same as the longitudinal (PI) decoding direction of the ECC decoder 23, and modulation / demodulation is performed using the ECC decoder 23. By performing ID verification on the ECC data sector 210 transmitted from the means 21, it is verified early whether the position of the read data sector 200 is accurate, and later of the ECC data block 25. When executing decoding, it is possible to prevent the occurrence of a problem that a data reading error is finally found and a lot of time is spent again to search for a new target sector. Therefore, when the ECC decoder 23 does not perform decoding of the ECC data block 25, the IED 212 and PI 214 in the ECC data sector 210 are immediately read, verification is performed on the ID 211 of the ECC data sector 210, and the verification result Is transmitted to the modem 21. The verification method is as follows.
[0016]
If the PI 214 data including the ID 211 (that is, the main data 213 plus the PI 214) fails to be decoded through the ECC decoder 23 (that is, an error in the sector number of the ECC data sector 210 included in the ID 211), an incorrect ID and Therefore, if the decoding is successful, the ID after decoding is checked again by the IED 212 to further confirm whether or not the ID is correct.
[0017]
In addition to the above verification method, another verification method is used in the present invention as follows.
[0018]
First, the modem 211 decodes the ID 211 using the IED 212, and then decodes the PI 214 data including the ID 211 and the IED 212 (that is, the main data 213 plus PI 214) by the ECC decoder 23. Is successful (that is, the sector number of the ECC data sector included in the ID 211 is accurate), the decoded ID is regarded as an accurate ID, and vice versa.
[0019]
(c) Step 32 ], When the ECC decoder 23 verifies the ID 211 of the ECC data sector 210 and the result is accurate, Step 33 Go to]. The DVD optical disc drive 2 estimates the location of the target sector in the optical disc 20 based on the sector number included in the ID 211. afterwards,〔 Step 34 Go to]. The DVD optical disk drive 2 starts its pickup head from the target sector, continuously reads the data sector 200 after the target sector into the modulation / demodulation means 21, converts the data sector 200 to the ECC data sector 210 through the modulation / demodulation means 21, and then sequentially stores the data buffer. When the ECC data sector 210 is stored in a predetermined amount and an ECC data block is formed, the data buffer 22 transmits the ECC data block to the ECC decoder 23 to perform decoding. In addition to this, while the ECC decoder 23 stores the ECC data sector 210 in the data buffer 22 as the ECC data block 25, [ Step 32 The ECC data block 25 is transmitted to the ECC decoder 23 for the ECC data sector 210 transmitted from the modulation / demodulation means 21, and decoding is performed. The ECC decoder 23 stores the ECC data sector 210 in the subsequent ECC data sector 210. The ID verification is continued until no ID verification is performed. This is because the ECC decoder 23 has to perform decoding on the ECC data block 25, and there is another reason that there is no time for executing the ID verification of the ECC data sector 210. This is because 200 is continuously recorded on the optical disc 20, and when it is already determined that the found target sector is the correct sector position, the data sector 200 following the target sector is necessarily accurate. Therefore, the redundant verification of the ECC decoder 23 is not necessary again. Thereafter, after the ECC data block 25 is transmitted to the ECC decoder 23, [Step 35] is executed to cause the ECC decoder 23 to perform the decoding operation on the ECC data block 25 and the error data correction operation. Therefore, when the ECC data sector 210 is just read and temporarily stored in the data buffer 22 using the ECC decoder 23, first, ID verification is performed on the ECC data sector 210, and the read data sector 200 is accurately detected. The ECC decoder 23 can be used effectively and sufficiently, and idle time is eliminated.
[0020]
(d) If the ID code verification result is an error, Step 30 ] ~ [ Step 32 ] Is repeated and executed. That is, when the ECC data sector 210 is transmitted to the ECC decoder 23, ID verification is performed, and an error is detected in the ID 211 of the ECC data sector 210 (that is, the ECC data sector 210 fails through PI decoding or the ECC data sector 210 is After decoding with the IED 212 through the modem 21, the ECC decoder 23 feeds back to the modem 21 and the modem 21 continues to perform ID verification of the next ECC data sector 210. Therefore, [ Step 30 Then, the modem 21 performs demodulation on the data sector 200 transmitted next, so that [ Step 31 ], The next ECC data sector 210 is generated, transmitted to the data buffer 22 and the ECC decoder 23, and the ECC data sector 210 initially stored in the data buffer 22 is error data (ID error). Thus, the next ECC data sector 210 transmitted in the data buffer 22 is overwritten on the ECC data sector 210 stored first. afterwards,〔 Step 32 ], The ECC decoder 23 performs ID verification on the next ECC data sector 210. This operation finds the ECC data sector 210 having an accurate ID, and thereby the ECC data sector 210 of the target ID. Will continue to be duplicated until estimated, otherwise prior to this, these subsequently stored ECC data sectors 210 in the data buffer 22 will continue to be overwritten by the initially stored ECC data sectors 210.
[0021]
Therefore, the DVD optical disk drive 2 searches for the target sector by the above method, and [ Step 35 ], After decoding is performed on the ECC data block 25 composed of the subsequent data sector starting from the target sector, these can be understood by referring to those shown in FIGS. The ECC data block 25 decoded by the ECC decoder 23 is transmitted to the data buffer 22 again via the data bus 24. afterwards,〔 Step 36 The descrambling and error detection code confirmation means 26 reads the main data of the ECC data block 25 in the data buffer 22 via the bus 24, and executes the descrambling and error detection code confirmation operation. On the other hand, when the main device side wants to read the data in the data buffer 22, [ Step 37 ], The ATAPI device 2 descrambles the main data in the ECC data block 25, transmits it to the main device side, and reproduces it.
[0022]
In the above method, the ECC decoder 23 serves the purpose of connection and multi-switch by the multiplexer 28, the modulation / demodulation means 21 and the data buffer 22. When the ECC decoder 23 does not decode the ECC data block 25, the multiplexer 28 connects the modulation / demodulation means 21 and the ECC decoder 23 so that the modulation / demodulation means 21 transmits the ECC data sector 210 to the ECC decoder 23 and performs ID verification. Can be executed. On the other hand, when it is necessary to decode the ECC data block 25 in the data buffer 22, the multiplexer 28 connects the data buffer 22 and the ECC decoder 23, so that the data buffer 22 converts the ECC data block 25 into the ECC decoder. It is possible to prevent the modulation / demodulation means 21 from transmitting the ECC data sector 210 to the ECC decoder 23 at the same time as transmitting to 23 and executing decoding.
[0023]
In summary, in the present invention, the idle time in which the ECC decoder 23 waits for the ECC data block 25 and the characteristic that the decoding directions of the ECC decoder 23 and the modulation / demodulation means 21 are the same are combined, and the multiplexer 28 is combined to create a DVD. The data sector 200 read by the optical disc drive 2 is demodulated by the modulation / demodulation means 21 to generate an ECC data sector 210. Then, the data sector 200 is transmitted to the data buffer 22 and temporarily stored. In this way, after confirming whether the ID of the ECC data sector 210 is correct or not, and after finding a data sector with higher accuracy based on this, the reading of the target sector and the subsequent data sector is performed for the first time. After forming the data block 25, the data block 25 is further transmitted to the ECC decoder 23 to be decoded. . As a result, it is possible to prevent the occurrence of a problem that a data read error is finally found when executing the decoding of the ECC data block 25 of the ECC decoder 23, and a new target sector must be searched again after a long time. It is possible to improve the data reading speed of the DVD optical disk drive 2 while improving the drawbacks in the known technology.
[0024]
Thus, the present invention is indeed an advanced design, no similar or similar products are found on the market, and certainly meet the patent requirements for novelty. Based on the application.
[0025]
However, what has been described above is merely a preferred embodiment of the present invention. Therefore, changes in equivalent structure made by applying the specification and claims of the present invention should be included in the patent scope of the present invention.
[0026]
[Brief description of the drawings]
In order that the purpose, effect and features of the present invention can be understood more clearly, the following description of the drawings is made in accordance with a more preferred embodiment of the present invention.
FIG. 1 is a block schematic diagram of a known recording media reader.
FIG. 2 is a diagram illustrating an example when an ID code error occurs in a data sector of a recording medium.
FIG. 3 is a diagram illustrating another example when an ID code error occurs in a data sector of a recording medium.
FIG. 4 is a block schematic diagram of a recording media reader in a preferred embodiment of the present invention.
FIG. 5 is a diagram showing the configuration contents of a data sector in a preferred practical example of the present invention.
FIG. 6 is a detailed flowchart of the method of the preferred embodiment of the present invention.
FIG. 7 is a diagram showing a configuration content of an ECC data sector in a preferred embodiment of the present invention.
FIG. 8 is a diagram showing a configuration content of an ECC data block in a preferred embodiment of the present invention.
[Explanation of symbols]
2 Recording media reading means
20 recording media
21 Modulation / demodulation means
22 Data buffer
23 Error correction code (ECC) decoder
24 buses
25 Error correction code (ECC) data block
26 Descramble and error detection code confirmation means
27 ATAPI equipment
28 Multiplexer
200 data sectors
201 ID code (ID)
202 ID error detection code (IED)
203 Main data
204 Error detection code (EDC)
210 Error correction code (ECC) data sector
211 ID code (ID)
212 ID error detection code (IED)
213 Main data
214 Internal parity code (PI), external parity code (PO)
251 Main data
252 Internal parity code (PI)
253 External parity code (PO)

Claims (5)

Retrieval of a target sector in a recording medium executed in a reading device of a recording medium, comprising: a modulation / demodulation means; a data buffer that composes an error correction code data block by temporarily storing a plurality of data sectors; and an error correction code decoder A method,
(A) An error correction code data sector having an ID code, an ID error detection code, and an internal parity code is generated by reading the data sector in the recording medium into the modulation / demodulation means, and then the error correction code Transmitting data sectors to the data buffer and the error correction code decoder, respectively;
(B) The error correction code decoder performs verification on the ID code of the error correction code data sector by reading the ID error detection code and the internal parity code in the error correction code data sector, and Transmitting the result to the modulation / demodulation means;
(C) performing steps (a) and (b) redundantly based on the error verification results;
(D) searching for the target sector in the recording medium based on an accurate verification result, starting from the target sector, sequentially storing subsequent data sectors in the data buffer, composing an error correction code data block; Transmitting to the error correction code decoder and performing decoding;
Including
In the step (d), while the error correction code decoder is waiting for the data buffer to transmit the error correction code data block, the modulation / demodulation means continues to receive data sectors from the recording medium. And verifying the ID code by transmitting the corresponding error correction code data sector to the data buffer and the error correction code decoder, respectively, so that the error correction code decoder is transmitted from the data buffer. When the received error correction code data block is received, the ID code verification process is temporarily suspended until the reception is completed, and the error correction code data block is decoded again. Target sector search method   2. The method according to claim 1, wherein the recording medium is an optical disk, and the recording medium reader is a DVD optical disk drive. A recording medium reading device that performs an accurate data reading operation by searching for a target sector in a recording medium,
Modulation / demodulation means for generating an error correction code data sector having an ID code, an ID error detection code, and an internal parity code by receiving a data sector in the recording medium and performing a demodulation operation;
A data buffer which is connected to the modulation / demodulation means and composes an error correction code data block by temporarily storing the error correction code data sector transmitted from the modulation / demodulation means;
By being connected to the modulation / demodulation means and the data buffer, ID code verification is performed on the error correction code data sector transmitted from the modulation / demodulation means, and further transmitted from the data buffer. An error correction code decoder that performs an error correction decoding operation on the error correction code data block that has been received,
Moreover, the modulation / demodulation means transmits the error correction code data sector to the data buffer and the error correction code decoder at the same time,
The error correction code decoder performs verification on the ID code of the error correction code data sector. If the verification result is accurate, the error correction code decoder searches for the target sector based on the ID code, and sends it to the recording media reader. Start from the target sector, sequentially store subsequent data sectors in the data buffer, wait for the composition of the error correction code data block, send the error correction code data block to the error correction code decoder and execute decoding If the verification result is not accurate, the modulation / demodulation means transmits the next error correction code data sector to the data buffer and the error correction code decoder until the data sector with the correct verification result is found. Perform ID code verification,
While the error correction code decoder has not yet performed decoding on the error correction code data block, the ID code of the error correction code data sector is verified, and the data buffer transmitted from the data buffer has been transmitted. When receiving an error correction code data block, the ID code verification operation is interrupted and the error correction code data block is decoded again . The recording medium reading device according to claim 3 , wherein the error correction code decoder performs verification on the ID code based on the ID error detection code and the internal parity code in the error correction code sector. apparatus. 4. The recording medium reading apparatus according to claim 3 , wherein the recording medium is an optical disk, and the recording medium reading apparatus is a DVD optical disk drive.

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