JP2000123490A - Optical disk reproducing device that error rate is reduced - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform reproducing operation well without causing disablement of reproduction or reduction of reproduction processing speed even in the case of an optical disk being in a bad state in which pit shapes are different depending on a region in a disk. SOLUTION: After a reproduced RF signal S1 is sliced by a comparator 1, it is supplied to a slice level generator 2, and a slice level signal S2 is generated. An error rate of a binary signal S3 is obtained by an ECC processing section 4, supplied to an error rate monitor processing section 5, when an error rate is small, the signal S2 is suppled to the comparator 1 through a changeover switch 6 and a reference voltage generator 3 (operation of auto-slice function). When an error rate is large and it cannot be corrected, a slice level at which an error rate is reduced based on a signal 4 is decided by the monitor processing section 5, supplied to the comparator 1 through a changeover switch 6 and a reference voltage generator 3, also a region is specified in a disk region discriminating section 7 for an appropriate value of a slice level and the value is stored, and it is used for calling by access command at the time of reproduction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk reproducing apparatus, and more particularly, to an optical disk (for example, a digital video disk or a compact disk) on which various types of information are recorded. The present invention relates to an optical disc reproducing apparatus capable of reducing an error rate in a reproduced information signal and performing a reproducing operation favorably even in a case of an optical disc in a bad state having different pit shapes.

[0002]

2. Description of the Related Art A conventional optical disk reproducing apparatus has a means for reducing an error rate when the error rate is too high to correct the error rate. Japanese Patent Laid-Open Publication No. Hei 9-171663 shows an example of this. Can be cited. FIG. 6 is a diagram showing the device of this conventional example in functional blocks, and an outline of the device configuration and its operation will be described with reference to FIG. As an apparatus configuration, there are a reproducing unit 10 for binarizing an analog information signal from an optical disc at a predetermined slice level and reproducing the same, and a reproducing unit 10 for reproducing a specific pattern written in a specific area of the optical disc.
Slice level changing means 20 for giving a plurality of offset values to a slice level used for value conversion and changing the level; error rate calculating means 30 for obtaining an error rate of reproduced data for each slice level; A slice level correction unit for determining an offset value for obtaining an appropriate slice level of a specific type of optical disk based on the error rate calculated by the calculation unit;

[0003] The operation of this optical disk reproducing apparatus is as follows.
MPU (Micro Processor Unit) 1 when playing an optical disc
The slice level changing means 20 operates to input an offset value to the binarizing circuit 15 with respect to the slice level for slicing the signal input from the peak bottom holder 14 in the reproducing means 10 for processing the signal from the optical disk. Attempt to reproduce at slice level A, and perform binarization processing. The error rate calculating means 30 compares an output obtained by decoding the binarized signal at this time (when the slice level A is set) through the decoder 16 with a test pattern stored in the test pattern memory 90 in advance. Then, the error rate Era is calculated, and the result is stored in the register Ra together with the slice level A. Next, the error rate Erb is calculated in the same manner as described above at the slice level B higher than the slice level A, and stored in the register Rb.
In this way, the slice levels are sequentially changed from A → B → C → D →
While increasing to E, the error rates Era, Erb, Erc, Erd, Ere at each slice level are stored in the corresponding registers Ra, Rb, Rc, Rd, Re.

[0004] Next, the slice level correction means 40 compares the error rates stored in the registers Ra to Re to determine the upper limit value and the lower limit value of the slice level where the error rate is equal to or less than the allowable value. Further, an intermediate value between the upper limit value and the lower limit value is set as an optimum slice level, and a correction point at which a midpoint between the peak level and the bottom level output from the peak bottom holder 14 becomes the optimum slice level is set as an offset value with respect to the midpoint. It is stored in the offset value memory 41. As a result, the optimum slice level is obtained, and subsequent reproduction is performed at the slice level in which the correction value is always offset with respect to the midpoint between the peak level and the bottom level output from the peak bottom holder 14. Reproduction is performed.

Another example of the prior art is disclosed in
No. 81368 can be mentioned. In this example, in the recording data signal reproducing system of the rewritable disk device, in the process of digitizing the read analog recording data signal, the slice level is controlled in accordance with the amplitude fluctuation of the analog data signal, and A reproduction method of an optical disk device provided with a circuit for reproducing data is disclosed.

[0006]

However, the above-mentioned 2)
In the case of the two prior arts, for example, no operation is described when the bit shape is different between the region near the inner periphery and the region near the outer periphery in the disc. Therefore, the following two operations are expected to be performed when such a disk is reproduced by the conventional apparatus. (1) For example, since the “optimal slice level” in the region near the inner periphery is stored in the storage means, slicing is performed at the “optimal slice level” when reproducing the region near the outer periphery. (2) The “slice level changing means” operates every time each area is accessed. When such an operation is performed, the following problems occur. In case (1) above, slicing is performed at a level different from the “optimal slice level” in the area near the outer periphery. In the worst case, reproduction becomes impossible. In the case of the above (2), it takes a considerable amount of time to access when the operation of “accessing the area near the outer circumference to the area near the outer circumference and accessing the area near the outer circumference to the inner circumference area” is frequently repeated. It slows down the processing speed.

In addition, in the case of the example disclosed in Japanese Patent Laid-Open Publication No. Hei 9-171663, the error rate is calculated by executing all the patterns of the slice level offset values prepared in advance. It always takes a certain time to find. Therefore, there is a problem that the remaining amount of the buffer for storing the reproduction data read from the optical disk is reduced, and the protection performance against data loss due to detection of scratches or dust on the optical disk during reproduction is unnecessarily reduced. It was something that could happen.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art. Even in the case of an optical disk having a bad pit shape depending on the area within the disk, it is impossible to reproduce data or to reduce the reproduction processing speed. It is an object of the present invention to provide an optical disk reproducing apparatus capable of satisfactorily reproducing an information signal without causing a problem.

[0009]

In order to solve the above-mentioned problems, the present invention provides means for constantly monitoring the error rate of a reproduced RF signal during reproduction of an optical disk, and slicing when the error rate deteriorates to an uncorrectable area. An error rate reduction device having a means for changing a level and a means for storing a once-reproduced area on an optical disc and a "reproducible slice level" for reproducing a bad optical disc Even in this case, the error rate is reduced by the operation of the error rate monitoring means and the slice level changing means to enable reproduction, and when accessing the once reproduced area or an area near the same, the access speed is improved. An optical disc reproducing apparatus characterized by performing an operation of causing a target area to be reliably reproduced. It is intended to.

The invention of each claim is constituted by the following technical means. The invention of claim 1 is a data signal generating means for obtaining a data signal by performing a slicing process based on a predetermined data slice level on a reproduction RF signal read from a recorded optical disk, and a data slice for changing the predetermined data slice level. Level changing means, and error rate detecting means for detecting an error rate of the data signal output from the data signal converting means, wherein the data slice level changing means is configured to reduce the error rate of the data signal to reduce the error rate of the data signal. In an error rate reduced optical disc reproducing apparatus which changes a predetermined data slice level based on an error rate detected by a rate detecting means, the data slice level changing value generated as an appropriate value by the data slice level changing means is stored on an optical disc. Identify and memorize the area of A data slice level change value storage unit that retrieves a data slice level change value of a corresponding area from the data slice level change value storage unit in response to an access command to an area on the optical disc, and reads the data slice level change value from the optical disc according to the access command. It is used for slicing a reproduced RF signal.

According to a second aspect of the present invention, in the optical disk reproducing apparatus with reduced error rate according to the first aspect, the apparatus further comprises a level measuring means for measuring a level variation of a data signal output from the data signal converting means, The data slice level changing means changes the predetermined data slice level based on the result measured by the level measuring means.

According to a third aspect of the present invention, in the error rate reduced optical disk reproducing apparatus according to the second aspect, the data slice level changing means is based on a value based on the error rate detected by the error rate detecting means, or The data slice level is changed by selecting one of the values based on the result measured by the level measuring means.

According to a fourth aspect of the present invention, in the optical disk reproducing apparatus with the reduced error rate according to the second aspect, the data slice level changing means sets the error rate detecting means to a value based on a result measured by the level measuring means. The data slice level is changed by selecting either a value obtained by adding a value based on the error rate detected in step 1 or only a value based on the result measured by the level measuring means. It is characterized by the following.

[0014]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a block diagram showing a configuration of an error rate reducing device provided in a first embodiment in which an optical disk reproducing device according to the present invention is applied to a digital video optical disk (hereinafter abbreviated as DVD). FIG. 2 is a conceptual diagram illustrating the area division on a disk used in the optical disk reproducing apparatus according to the present invention. With reference to FIGS. 1 and 2, the configuration and operation of the device of this embodiment will be described below.

In the initial operation state of the apparatus, the changeover switch 6 is set to the side 6-1. The reproduction RF signal S1 obtained from the DVD passes through the comparator 1 and is supplied to the slice level generator 2. The slice level generator 2 measures the frequency of the “high” and “low” sections of the comparison result of the comparator 1, and generates a slice level of the difference amount via a smoothing circuit. And
This slice level is output as D / A converted signal S2. On the other hand, the slice signal S3 output through the slice level generator 2 is supplied to the ECC processing unit 4, and the error rate signal S4 measured by the ECC processing unit 4 is supplied to the error rate monitoring processing unit 5.

When the error rate monitoring processor 5 determines that the value of the error rate signal S4 is small, that is, the level is correctable, the changeover switch 6 is set to the side 6-1 (the same as the initial state). Thus, the slice level D / D determined by the slice level generator 2
A conversion signal S2 is supplied to reference voltage generator 3,
It is converted to a voltage value and supplied to the comparator 1. The operation in this case is that the conventional “auto slice function” is operating. When the error rate monitoring processing unit 5 determines that the value of the error rate signal S4 is a large and uncorrectable level, a process of determining a slice level for reducing the error rate based on the error rate signal S4 is performed. And the slice level determined is D
It is output as the / A conversion signal S5. At this time, the D / A conversion signal S5 is supplied to the reference voltage generator 3 by switching the changeover switch 6 to the 6-2 side, converted into a voltage value, and supplied to the comparator 1.

By repeating the operation of changing the slice level as described above, the data is sliced at an appropriate level with respect to the reproduction RF signal S1, and the ECC processing unit 4 performs the ECC processing for reducing the error rate, and performs the reproduction signal. Is obtained as its output. If the area on the disk reproduced at this time is the area (A) in FIG. 2 (near the inner circumference), the slice level value at that time is stored in a memory (not shown) in the host microcomputer (not shown). It is stored in SL1 (in the discriminating section 7). Similarly, when the area (B) in FIG. 2 (near the middle between the inner circumference and the outer circumference) is reproduced, the slice level value at that time is stored in the memory SL2 on the host microcomputer, and the area (C) in FIG. When the (nearby) is reproduced, the slice level value at that time is stored in the memory SL3 on the host microcomputer. By performing the above operations, the following operations can be performed.

That is, the disk area discriminating section 7 has a function of judging which area to be reproduced corresponds to an area for which a slice level is prepared, and specifying the area. If the host microcomputer issues an access command to the vicinity of the inner peripheral area during reproduction in the vicinity of the outer peripheral area, the disc area determination unit 7 determines that "the target reproduction area is the area (A) in FIG. 2". Memory SL
1 is selected and output as a D / A converted slice level signal S7. At this time, by switching the changeover switch 6 to the 6-3 side, the signal S7 is supplied to the reference voltage generator 3, converted into a voltage value, and supplied to the comparator 1. Therefore, a slice level suitable for the area to be reproduced is immediately obtained, and a time loss due to an operation (slice level change and error rate reference repetition) performed during slice level adjustment is eliminated. In the case where the reproduction is continuously performed from the vicinity of the inner circumference area to the vicinity of the outer circumference area, at the point where the reproduction area switches from the area (A) to the area (B), the “appropriate slice level” is changed from SL1. Assuming an intermediate value of SL2,
What is necessary is just to set to that value. Similarly, at the point where the playback area switches from the area (B) to the area (C), the “appropriate slice level” may be set to an intermediate value between SL2 and SL3. By the way, in the example of FIG. 2, the area is divided into three, but the number of divisions is only an example and does not limit the configuration of the present invention at all.

FIGS. 3 and 4 are flow charts showing the operation (operation performed by the CPU) in the embodiment of FIG. 1, in particular, the control method of the error rate review processing unit 5 and the changeover switch 6. A series of processes shown in FIG. 3 and FIG.
This is a process that is periodically executed at appropriate time intervals during VD playback. This operation is started by a reproduction command from the host. When a reproduction command is issued from the host, the changeover switch 6 is set to the side 6-1 in the initial state. Therefore, the slice level of the reproduction RF signal S1 is determined by the “auto slicing function” of the slice level generator 2, and the sliced signal S3 is supplied to the ECC processing unit 4. The ECC processor 4 measures an error rate S4 for the signal S3 (step S21). next,
In the error rate monitoring processing unit 5, the processing branches depending on whether the current mode is the “auto slice operation mode” (step S).
22). In step S22, in the case of the "auto-slice operation mode" (the initial state of the system is always the "auto-slice operation mode"), a criterion for judging whether or not to stop the auto-slice operation (reproduction or access command to the same address) Are repeated four times or more, and the error rate cannot be corrected four times continuously) (step S23). If the determination criterion is not met, the processing of FIG. Move to.

If the data could not be read out, the host again issues an access command to the same location on the disk, that is, the same address, so that FIG.
Is operated and the process goes through the step 23. That is, step S23 is performed four times in succession with the error rate being large, so that the judgment criterion is met and the auto slicing operation is stopped (step S24). Setting the condition of “four times or more” in step S23 is an example of a countermeasure for preventing a malfunction when a temporary error rate is deteriorated due to a scratch or dust on a disk. It does not limit the invention in any way.

After step S24, the CPU reads the slice level in the auto slicing operation, and determines a slice level fixed value different from this value. At this stage, it is not possible to determine whether to set the level higher or lower than the read value. For example, the slice level fixed value is temporarily set to a value smaller than the value, and the “slice level fixed value mode” is set. (Step S2
5). That is, the changeover switch 6 is set to 6-2
And supplies the reference voltage generator 3 with the D / A conversion signal S5 having the fixed slice level determined by the error rate monitoring processor 5. Step S2
5, the slice level in the auto slice operation is set to C
If the slice level cannot be read by the PU, the slice level fixed value is set to, for example, a value near the center value of the possible values, and the verification is performed on the actual device. May be determined as the initial value.

In the flow of FIG. 4, the operation of the "slice level fixed value mode" for the signal sliced by the "slice level fixed value" set as described above is executed. First, in step S22, the mode is the “slice level fixed value mode”.
Go to 31. If the error rate cannot be corrected in step S31, it is checked whether or not the reproduction target area has been reproduced in the "slice level fixed value mode" in the past (step S32). A comparison is made with the error rate value at the level set value (step S34).

If the value of the error rate is higher than the previous time, it is determined that the direction of changing the slice level (whether to increase or decrease the fixed slice level value from the previous time) is incorrect, and the slice level is fixed. Set the value in the opposite direction to the previous value. That is, if the value was previously increased, a small value is set, and if the value was previously decreased, a large value is set (step S35). In step S34, when the value of the error rate has not become larger than the previous time, that is, when it has become smaller or hardly changed, it is determined that the direction of changing the slice level is correct, and the slice level fixed value is changed to the previous value. The value is further changed to the same direction (a large value if it was previously increased, a small value if it was previously decreased) (Step S)
36).

By repeating the above processing, the error rate becomes a correctable level at a certain slice level fixed value, a signal S6 having a small error rate is output from the ECC processing unit 4, and the information recorded on the disk is Reproduction becomes possible. When the process of FIG. 4 is executed in a state where the error rate is reduced in this way, the process proceeds to step S41 by branching to step S31. Since the slice level corresponding to the currently reproduced area has not been stored in the memory yet, the current slice level value is stored in the memory corresponding to the currently reproduced area. For example, if the area currently being reproduced is the area (A) in FIG. 2, the memory SL1
The value of the slice level is stored (step S42).

In step S32, if the disk has been reproduced in the past, the disk area discriminating section 7 operates to select the slice level value at that time (for example, SL2 in the area (B) of FIG. 2) ( Step S33), D / A
Since the conversion signal S7 is output, the changeover switch 6 is set to 6-
By switching from the 2 side to the 6-3 side, the D / A conversion signal S
7 is supplied to the reference voltage generator 3 and sliced at an appropriate slice level in the reproduction target area. Therefore, the error rate becomes a correctable level, and the ECC processing unit 4
Outputs a signal S6 having a small error rate.

Although not shown in FIGS. 3 and 4,
If reproduction is not possible even if the slice level value used in the past is used, processing for changing the slice level value is performed again. A process for returning from the “slice level fixed value mode” to the “auto slice operation mode” is also required. In other words, if the error rate is low and stable,
Since the error rate is low in step S31, the process proceeds to step S41. Since the slice level for the area has been stored, the process proceeds to step S43. Here, since the state where the error rate is small stably continues, the mode shifts to the "auto slice operation mode" (step S44). Step S43
As an example, there is a concept that "a state in which an error rate is equal to or less than a certain value is continuous for a certain time or more, and a difference between a slice level value and an auto slice level value at that time is within two levels". .

By the way, the operation of the CPU shown in the above embodiment is only an example, and does not limit the configuration of the present invention. For example, the criterion in step S23 does not limit the processing in the error rate monitoring processing unit 5 in any way. Similarly, steps S31 to S4
The processing of 4 does not limit the processing in the error rate monitoring processing unit 5 in any way. The best algorithm may be determined in consideration of the configuration of the entire system.

FIG. 5 is a block diagram showing a configuration of an error rate reducing device provided in the second embodiment to which the optical disk reproducing device according to the present invention is applied. Note that FIG.
Are commonly used in this embodiment. The configuration and operation of the device according to the second embodiment will be described below with reference to FIGS. In the initial operating state of the apparatus, the changeover switch ₆₁ is Yes set to 6 ₁ -1 side, the changeover switch 6 ₂ is set at 6 ₂ -1 side. The reproduced RF signal S1 obtained from the DVD is transmitted via the comparator 1 and the slice level generator 2 as in the first embodiment.
The slice level is output as a D / A converted signal S2 and a sliced signal S3. The signal S3 is EC
The error rate S4 supplied to the C processing unit 4 and measured by the ECC processing unit 4 is supplied to the error rate monitoring processing unit 5.

[0029] In the error rate monitoring unit 5, the value of the error rate S4 is small, that is, if it is determined that the correctable level, likewise the switch 6 ₁ of the first embodiment ₆₁ -1 side (The same as the initial state) to operate the “auto slice function”. However,
In the error rate monitoring processor 5, the error rate S4
Is determined to be a large and uncorrectable level, the value of the difference between the slice level signal S2 generated by the slice level generator 2 and the slice level signal that reduces the error rate (hereinafter, “slice level”) (Referred to as “level offset value”) based on the error rate S4. The determined result is D / A
The converted signal S5 is output.

On the other hand, since the signal S6 after the ECC processing includes the address information on the disk, the area currently being reproduced by the disk area determination unit 7 is shown in FIGS.
Is determined, and the reproduction has not been performed in the past (the slice level offset value is SL1 to SL
3 is not stored), then the change-over switch 6 ₂ 6 ₂
By setting to the -1 side (the same as the initial setting), the above D /
A conversion signal S5 is supplied to the adder 8, after being added to the slice level signal S2 generated by the slice level generator 2, the reference voltage generator 3 by switching on the switch 6 ₁ 6 ₁ -2 side The voltage is supplied, converted into a voltage value, and supplied to the comparator 1.

By repeating the above-described operation of changing the slice level offset value, data slicing is performed at an appropriate level with respect to the reproduced RF signal S1, thereby enabling reproduction after ECC processing with a reduced error rate. Signal S6 is obtained. Then, the slice level offset value is stored in the memory on the host microcomputer in the same manner as in the first embodiment, corresponding to the area on the disk reproduced at this time. By performing the above operations, the following operations can be performed.

That is, when an access command to the vicinity of the inner peripheral area is issued from the host microcomputer during reproduction in the vicinity of the outer peripheral area, the disc area discriminating section 7 states that "the target reproduction area has been reproduced in the past, which is shown in FIG. Of the memory SL1 is selected and output as the slice-level offset signal S7 after D / A conversion. At this time, since the signal S7 is supplied to the adder 8 by switching the changeover switch 6 ₁ 6 ₁ -2 side, the slice level signal S2
After being added to, is supplied to the reference voltage generator 3 (remains switched to the change-over switch 6 ₁ 6 ₁ -2 side) is converted into a voltage value, it is supplied to the comparator 1. Therefore, as in the first embodiment, a slice level suitable for the area to be reproduced is immediately obtained.

In the case of continuous reproduction from the vicinity of the inner peripheral area to the vicinity of the outer peripheral area, the reproduction area is cut from the area (A) to the area (B) as in the first embodiment. At the replacement point, it is assumed that the “appropriate slice level offset value” is an intermediate value between SL1 and SL2, and may be set to that value. Similarly, at the point where the playback area switches from the area (B) to the area (C), the “offset value of the appropriate slice level” is set to SL.
It may be set to an intermediate value between 2 and SL3.

[0034]

According to the present invention, even in the case of reproducing a bad disk in which the pit shape is different between the area near the inner circumference and the area near the outer circumference in the disk, data at an appropriate level with respect to the reproduced RF signal can be obtained. Since slicing is performed, a correctable signal with a small error rate is obtained even for a signal that could not be reproduced on either the inner circumference or the outer circumference in the past, and can be reproduced. In addition, even when an access operation from the inner circumference to the outer circumference or from the outer circumference to the inner circumference is performed on such a disc, data slicing is performed immediately at a slice level that can be reproduced in each area, and reproduction processing without time loss is performed. Will be

Further, in the slice level changing operation, when the error rate becomes correctable, the changing operation is stopped, and even if the error rate is further reduced at a slice level different from this slice level, the slice level is changed. The level is not changed, that is, unnecessary time is not spent on the slice level changing operation. Therefore, since there is no waste in reducing the remaining amount of the buffer for storing the reproduction data read from the optical disk, it is possible to prevent a reduction in protection performance against data loss due to detection of scratches or dust on the optical disk during reproduction. Can be done.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an error rate reducing device provided in a first embodiment of an optical disc reproducing device according to the present invention.

FIG. 2 is a conceptual diagram illustrating an area division on a disk used in an optical disk reproducing device according to the present invention.

FIG. 3 is a flowchart (part 1) illustrating an operation in the embodiment of FIG. 1, particularly a method of controlling an error rate monitoring processing unit and a changeover switch.

FIG. 4 is a flowchart (part 2) illustrating an operation in the embodiment of FIG. 1, particularly a method of controlling an error rate monitoring processing unit and a changeover switch.

FIG. 5 is a block diagram showing a configuration of an error rate reducing device provided in a second embodiment to which the optical disc reproducing device according to the present invention is applied.

FIG. 6 is a diagram showing a conventional optical disc reproducing apparatus in functional blocks.

[Explanation of symbols]

1 ... Comparator, 2 ... slice level generator, 3 ... reference voltage generator, 4 ... ECC processing unit, 5 ... error rate monitoring unit, 6,6 _1, 6 ₂ ... changeover switch, 7 ... disk region discriminator, 8 ... Adder, 10 reproducing means, 14 peak-bottom holder, 15 binarization circuit, 16 decoder, 20 slice level changing means, 30 error rate calculating means, 40 slice level correcting means, 90 test Pattern memory, 100 ... MPU.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G11B 20/18 572 G11B 20/18 572C (72) Inventor Naoshi Nishikaku 22nd Nagaikecho, Abeno-ku, Osaka-shi, Osaka 22 Sharp Corporation (72) Inventor Wataru Terui 22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka F-term (reference) 5D044 BC02 CC04 DE45 EF05 FG06 5D090 AA01 BB04 CC06 EE14 GG33

Claims (4)

[Claims] 1. A data signal generating means for obtaining a data signal by performing a slicing process based on a predetermined data slice level on a reproduction RF signal read from a recorded optical disk, and a data slice level changer for changing the predetermined data slice level Means, and error rate detection means for detecting an error rate of the data signal output from the data signal conversion means, wherein the data slice level changing means detects the error rate in order to reduce the error rate of the data signal. An error rate reduced optical disc reproducing apparatus wherein the predetermined data slice level is changed based on the error rate detected by the means, wherein the data slice level change value generated as an appropriate value by the data slice level changing means is stored in an area on the optical disc. Identify and memorize Data slice level change value storage means, and fetches a data slice level change value of a corresponding area from the data slice level change value storage means in response to an access command to an area on the optical disc, and reads the data slice level change value from the optical disc by the access command. Play R
An optical disk reproducing apparatus with a reduced error rate used for slicing an F signal. 2. The optical disk reproducing apparatus with reduced error rate according to claim 1, further comprising a level measuring means for measuring a level change of a data signal output from said data signal converting means, wherein said data slice level changing means. Wherein the predetermined data slice level is changed on the basis of the result measured by the level measuring means. 3. An optical disc reproducing apparatus with reduced error rate according to claim 2, wherein said data slice level changing means is based on a value based on an error rate detected by said error rate detecting means, or said data slice level is changed by said level measuring means. An optical disk reproducing apparatus with a reduced error rate, characterized in that the data slice level is changed by selecting one of the values based on the measured result. 4. The error rate reduced optical disc reproducing apparatus according to claim 2, wherein said data slice level changing means detects an error detected by said error rate detecting means to a value based on a result measured by said level measuring means. An error characterized in that the data slice level is changed by selecting either a value obtained by adding a value based on a rate or only a value based on a result measured by the level measuring means. Optical disc playback device with reduced rate.