JP2003077132A - Information recording medium and information recording and reproducing device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To set up the optimum level of multi-valued information according to the state of a medium and a device, when multi-valued information is recorded to an information recording medium. SOLUTION: Before information is recorded in an information recording area of an optical disk 10, a controller 12 performs trial recording at a multi- valued level in a trial recording area assigned separately from the information recording area and determines the maximum recordable multi-valued level according to the number of errors in every multi-valued level obtained when the trial recording area is reproduced. For example, the number of the multi- valued level is determined as the maximum level in the range where the number of errors does not exceed a threshold value, namely, the level directly before the number of errors suddenly increases.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information recording medium and information recording / reproducing apparatus for recording / reproducing information using multi-valued information.

[0002]

2. Description of the Related Art Normally, information is recorded in binary on an information recording medium, but an information recording / reproducing medium and a recording / reproducing apparatus therefor capable of multi-valued recording / reproducing to improve the recording density of information are proposed. Has been done. When recording multi-valued information, the amount of information that can be recorded and reproduced changes depending on the number of multi-valued levels indicating how many levels are separated and recorded.

FIG. 9 shows an example of multilevel recording. For example, information such as light reflectance, for example, the amount of reflected light is converted into a voltage,
Information is recorded by dividing the voltage into eight levels. When reproducing, information is reproduced by AD (Analog-Digital) conversion into eight levels. In this example, since it has 8 values, 2 of 3
Power, that is, 3-bit information is recorded / reproduced in a unit time. Increasing this multilevel level increases the capacity, but reduces the reliability of information. Therefore, the number of levels can be reduced when applied to a system requiring reliability, and the number of levels can be increased when applied to a system relatively unreliable.

[0004]

However, depending on the state of the information recording medium or the information recording / reproducing apparatus, it may not be possible to record / reproduce at the maximum multi-value level capable of recording / reproducing, and by forcibly increasing the capacity. This will reduce the reliability of the information.

The present invention has been made in view of the above circumstances. When performing multi-value recording, trial writing is performed in advance on an information recording medium, and the multi-value level is determined according to the state of the information recording medium. Accordingly, it is an object of the present invention to provide an information recording medium and an information recording / reproducing apparatus for the same, which can determine an optimum recording state.

[0006]

According to a first aspect of the present invention, there is provided an information recording medium on which multi-valued information is recorded, and a trial for determining a recordable multi-valued level separately from an information recording area. It is characterized in that the writing area is allocated. According to the invention described in claim 1, since the trial writing area for determining the multi-valued level is provided, the number of multi-valued levels can be determined for each recording medium, and the reliability of information recording / reproducing can be improved. become.

According to a second aspect of the present invention, there is provided an information recording device for recording multi-valued information on an information recording medium, wherein the information recording area is recorded before the information is recorded in the information recording area of the information recording medium. To perform trial writing at a multi-valued level in the test writing area allocated separately from the test writing area, and determine the maximum recordable multi-valued level according to the number of errors at each multi-valued level when the test writing area is reproduced. Is characterized by. Claim 2
According to the invention described in (1), the number of multi-valued levels is determined in the trial writing area before recording, and the number of errors is used to determine the number of multi-valued levels. It becomes possible to improve the property.

According to a third aspect of the present invention, in the information recording / reproducing apparatus according to the second aspect, it is possible to record within a range in which the number of errors for each multi-value level when reproducing the trial writing area does not exceed a predetermined threshold value. It is characterized by determining the maximum multi-valued level. According to the third aspect of the present invention, there is provided an information recording / reproducing apparatus which is improved in reliability by determining the maximum level in which the number of errors does not exceed the threshold value in determining the number of multi-valued levels. be able to.

According to a fourth aspect of the invention, in the information recording / reproducing apparatus according to the second or third aspect, the number of errors when trial writing is performed at a certain multi-value level and the multi-value less than the multi-value level. It is characterized in that a difference from the number of errors when trial writing is performed at the level is taken, and the maximum recordable multilevel level is determined within a range in which the difference does not exceed a predetermined threshold value. According to the invention of claim 4, the reliability is determined by setting the maximum level in which the number of errors does not exceed the threshold value in determining the number of multi-valued levels, and by determining the level immediately before the number of errors suddenly increases. It is possible to provide an information recording / reproducing device which is improved.

According to the invention of claim 5, claim 2
5. The information recording / reproducing apparatus according to any one of items 1 to 4, wherein trial writing for determining the maximum recordable multi-valued level is performed every time information is recorded in the information recording area. . According to the invention of claim 5,
By detecting the optimum value of the multi-valued level each time recording is performed, the reliability of the multi-valued level information recording / reproducing can be improved.

The invention according to claim 6 is the invention according to claims 2 to 4.
In the information recording / reproducing apparatus described in any one of 1. above, trial writing for determining the maximum recordable multi-valued level is performed only when the recording medium is loaded into the apparatus, and it is determined at this time. It is characterized in that information is recorded at a multilevel level. According to the sixth aspect of the present invention, the optimum value of the multi-valued level is detected only when the information recording medium is loaded in the information recording / reproducing apparatus, the value is held, and is read and set each time recording is performed. The overhead is reduced, and the processing time for detecting the optimum value of multi-level is shortened.

[0012]

DETAILED DESCRIPTION OF THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of an information recording / reproducing apparatus of the present invention. Here, an optical disc is exemplified as the information recording medium, but the present invention does not depend on the recording system of the information recording medium, and the same effect can be obtained for all magneto-optical, write-once, and rewritable recording media.

When a command (not shown), for example, a host device such as a personal computer is sent to an optical disk drive as an information recording / reproducing device, the interface controller 11 receives the command and reports to the controller 12 that the command has been received. Specifically, the controller 12 is composed of a peripheral LSI including a CPU and a memory, and the CPU sequentially reads out and executes a program recorded in the memory to control the operation described below. That is, the controller 12 interprets the command, causes the optical disk drive to perform the operation requested by the command, and notifies the upper device of the result through the interface controller 11.

For example, when recording information, the information is temporarily stored in the buffer memory 14 from the host device through the interface controller 12 and the digital circuit 13. For this information, the digital circuit 13
Then, an error correction code is added, a synchronization signal is added, or a modulation code to a multilevel is converted. When actually recording, the address written in advance on the optical disk 10 is read and the information is written at the instructed address.

Next, the analog circuit 15 drives the optical disk 10
The LD (Laser Dio) on the pickup 18
The current is controlled so that (de) is emitted and recording is performed at a multilevel level. Further, in the pickup 18, the light emitted from the LD hits the optical disk 10, and the reflected light is reflected by a PD (Photo Detecto).
r), and the analog circuit 15 processes it to generate an FE (focus error) signal, a TE (tracking error) signal, etc., which are input to the servo circuit 16 and the servo circuit 1
6 controls the position of the pickup 18 and the lens position. The optical disk 10 usually has a spiral groove or data array. Therefore, it moves from the inner circumference to the outer circumference (or vice versa) with the lapse of time, and exceeds the range in which tracking control is possible. Therefore, the servo circuit 16
Performs a control called a calitra so that the entire pickup 18 is moved from the tracking servo signal so that the lens position can always be kept close to neutral.

On the other hand, in the case of reproduction, the output of the pickup 18 is quantized by the analog circuit 15, and the PLL (Phas
e Locked Loop) to extract the clock,
The digital circuit 13 performs synchronization detection, demodulation, error correction, etc., and stores the output in the buffer memory 14. After that, the information is transferred to the host device through the interface controller 11.

FIG. 2 shows an embodiment of a multilevel variable modulation circuit used in the information recording / reproducing apparatus of the present invention. The modulation circuit 131 shown here is built in the digital circuit 13 shown in FIG. The modulation circuit 131 has a multilevel control signal “co” generated and output by the controller 12.
nt "as an input, which sets a multi-level, a modulation code is generated and supplied to the analog circuit 15. For example, as shown in Table 1 in FIG. If is "1", "1" shown in FIG.
"0" and "7" levels are used, and in the case of "2",
A modulation code is generated by using four values of "0", "2", 4 ", and" 6 "to improve reliability. In Table 1 shown in FIG. "," 4 "," 8
It is expressed by "and a power of 2, but it is not particularly limited.

FIG. 4 shows an embodiment of a multilevel variable demodulation circuit used in the information recording / reproducing apparatus of the present invention. The multilevel variable demodulation circuit is composed of a quantizer 132 and a demodulator 133, and is built in the digital circuit 13 shown in FIG. Here, the reproduction data output from the analog circuit 15 is used as a quantizer 132 including an AD converter.
And quantized data is used as output data. The demodulator 133 includes a controller 12 in addition to the quantized data.
The multi-valued level control signal "cont" is obtained from the above, and the inverse conversion to the above is performed to convert the quantized data into demodulated data by the multi-valued level control signal "cont", and the demodulated data is supplied to the interface controller 11.

In such a method of recording by changing the multi-valued level, it is important to judge which multi-valued level should be recorded according to the information medium to be recorded.
Therefore, before recording, a test is performed to determine at what level recording should be performed, and the multilevel level is determined from the result. FIG. 5 is a flowchart showing the procedure for determining the multilevel level. The flowchart shown in FIG. 5 is previously recorded as a program in the memory built in the controller 12 shown in FIG.

First, the pickup 18 is moved to a test writing area provided on the optical disk 10 for determining a predetermined recording condition (step S501), and recording is performed while changing the multilevel level (step S502). .
Then, the trial writing place is reproduced (step S50).
3) Determine the optimum number of levels (step S50)
4). The trial writing location is provided, for example, on the inner circumference (or on the outer circumference or in the middle) of the data area, as shown in FIG.

At this time, in order to obtain the optimum number of levels, a judgment is made using the error rate which is the number of errors in a certain section. The number of levels and the error rate usually have a relationship as shown in FIG. FIG. 7 is a graph showing the relationship between the number of errors on the vertical axis and the multilevel level on the horizontal axis. According to FIG. 7, the performance (reading) deteriorates at an almost constant rate up to the middle, and rapidly deteriorates from a certain point. Here, using this number of errors, the level of the number of errors smaller than a predetermined number (a straight line in the figure) is obtained as an optimum value.

Further, the difference in the number of errors from the level before trial writing in order to make the optimum value before the sudden deterioration,
Specifically, by performing a differential operation, the level before the difference becomes larger than the threshold value may be set as the optimum value. In FIG. 8, the vertical axis shows the difference from the previous value of the error number, the horizontal axis shows the level number, and the threshold value at that time is shown by a straight line. Furthermore, by combining the two, a more reliable information recording medium and its information recording / reproducing apparatus can be obtained.
That is, the level that satisfies both the conditions shown in FIG. 7 and FIG. 8 is set as the optimum value.

In order to obtain this optimum value, as shown in FIG. 5, the above control is performed every time recording is performed, and the recording level as the optimum value is set (step S50).
5) The information recording is started (step S506). However, since it takes time to perform the trial writing for each recording and determine the optimum value, the controller 12 detects that the optical disk 10 is loaded in the optical disk drive, and the first 1
Processing time can be shortened by performing trial writing only once. Then, the recording level can be determined by saving the information at this time in the memory built in the controller 12 and reading it out appropriately.

As described above, according to the present invention, when multi-value recording is performed, test writing is performed in advance on the information recording medium,
It is possible to provide an information recording medium and an information recording / reproducing apparatus for the information recording medium, in which the optimum recording state can be determined by determining the multilevel level according to the state of the information recording medium.

[0025]

According to the first aspect of the present invention, since the test writing area for determining the multi-valued level is provided, the multi-valued level number can be determined for each recording medium, and the reliability of information recording / reproducing can be improved. It will be possible to improve.

According to the second aspect of the present invention, the number of multi-valued levels is determined in the trial writing area before recording, and the number of errors is used to determine the number of multi-valued levels. It becomes possible to improve the reliability of multi-level.

According to the third aspect of the present invention, the information recording / reproducing apparatus is improved in reliability by determining the maximum number of errors in the number of multi-valued levels that does not exceed the threshold value. Can be provided.

According to the fourth aspect of the invention, the number of multi-valued levels is determined to be the maximum level in which the number of errors does not exceed the threshold value, and the level immediately before the number of errors suddenly increases is determined. Thus, it is possible to provide an information recording / reproducing apparatus with improved reliability.

According to the invention described in claim 5, by detecting the optimum value of the multi-valued level each time recording is performed, the reliability of the multi-valued level information recording / reproducing can be improved.

According to the sixth aspect of the present invention, the optimum value of the multi-valued level is detected only when the information recording medium is loaded in the information recording / reproducing apparatus, the value is held, and is read and set each time recording is performed. Therefore, the overhead is reduced and the processing time for detecting the optimum value of multi-valued level is shortened.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of an information recording / reproducing apparatus of the present invention.

FIG. 2 is a block diagram showing an embodiment of a multilevel variable modulation circuit used in the information recording / reproducing apparatus of the present invention.

FIG. 3 is a diagram showing, in a tabular form (<Table 1>), a relationship between a multilevel control signal, a number of multilevels, and a use level used in the present invention.

FIG. 4 is a block diagram showing an embodiment of a multilevel variable demodulation circuit used in the information recording / reproducing apparatus of the present invention.

FIG. 5 is a diagram quoted for explaining the operation of the embodiment of the present invention, and is a diagram showing a flowchart of a procedure for determining a multilevel level.

FIG. 6 is a diagram quoted for explaining the data structure of the information recording medium of the present invention.

FIG. 7 is a diagram cited to explain the operation of the exemplary embodiment of the present invention, and is a graph showing the relationship between the number of errors and the multilevel quantization level.

FIG. 8 is a diagram cited to explain the operation of the exemplary embodiment of the present invention, and is a graph showing the relationship between the difference in the number of errors and the multilevel quantization level.

FIG. 9 is a diagram cited for explaining multi-valued recording.

[Explanation of symbols] 10 optical disc 11 Interface controller 12 Controller 13 Digital circuit 14 buffer memory 15 analog circuit 16 Servo circuit 17 Spindle motor 18 pickup

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 5D044 BC02 CC04 DE68 EF05 FG18                       GK12                 5D090 CC01 DD03 DD05 EE01 GG33                       JJ12                 5D119 AA22 AA23 AA41 HA19 HA48                 5D789 AA22 AA23 AA41 HA19 HA48

Claims (6)

[Claims] 1. An information recording medium on which multi-valued information is recorded, wherein a test writing area for determining a recordable multi-valued level is allocated separately from the information recording area. Medium. 2. An information recording apparatus for recording multi-valued information on an information recording medium, wherein a trial allocated separately from the information recording area prior to recording information on the information recording area of the information recording medium. Information recording / reproducing characterized in that trial writing is performed in the writing area at a multilevel level, and the maximum recordable multilevel level is determined according to the number of errors in each multilevel level when the test writing area is reproduced. apparatus. 3. The maximum recordable multi-valued level is determined within a range in which the number of errors for each multi-valued level when the test writing area is reproduced does not exceed a predetermined threshold value.
The information recording / reproducing apparatus described in. 4. A difference between the number of errors when trial writing is performed at a certain multi-level level and the number of errors when trial writing is performed at a multi-level less than the multi-level, and the difference is predetermined. 4. The information recording / reproducing apparatus according to claim 2, wherein the maximum recordable multi-valued level is determined within a range not exceeding the threshold value. 5. The method according to claim 2, wherein trial writing for determining the maximum recordable multi-valued level is performed every time information is recorded in the information recording area. Information recording / reproducing apparatus described. 6. The test writing for determining the maximum recordable multi-valued level is performed only when the recording medium is loaded in the apparatus, and the information is recorded at the determined multi-valued level. The information recording / reproducing apparatus according to any one of claims 2 to 4, characterized in that: