JPH05258464A - Method and device for binarization - Google Patents

Abstract

PURPOSE:To provide the method and device for binarization capable of reproducing recording data recorded on an information recording medium. CONSTITUTION:In binarizing a reproduction signal (d) from the information recording medium recording NRZI code data, the first threshold value Th1 and the second threshold value Th2 are set to detect the leading and trailing edge positions of the NRZI code data based on the reproduction signal (d). The binarization of the reproduction signal (d) is performed based on the first threshold value Th1 and the second threshold value Th2, and a binary pulse (i) is to be generated at the position to be detected even though the recording mark shape is irregular.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a binarization method and an apparatus for use in signal reproduction of an optical disk drive device or a magneto-optical disk drive device.

[0002]

2. Description of the Related Art In an optical disk drive device and a magneto-optical disk drive device, there is a mark edge recording method as a recording method suitable for high density recording. This is a recording method in which two modulation bits are recorded in one mark to improve the recording density as shown in FIG. 13, and the modulation code is NRZI (NonR) as a recording data pattern.
eturn to Zero Inverse) Converted to code data and recorded on a disc (information recording medium). During data reproduction, the reproduction signal is binarized by detecting two edge positions corresponding to the rising and falling edges of the NRZI code data of the reproduction signal obtained from the disc.

FIG. 14 shows a first conventional example of such a binarization method. The comparator (CP) 1 compares the level of the reproduction signal (d) obtained from the disc with a preset threshold Th, and detects the edge pulse detector (ED) from the output signal (e) of the comparator 1. The binary pulse (f) is generated by detecting two edge positions corresponding to the rising edge and the falling edge of the NRZI code data.

A second conventional example is shown in FIG.
This is because the reproduction signal obtained from the disc is subjected to second differentiation by the second differentiation circuit 3 and the level of the output signal is compared with the ground level by the comparator (CP) 4 to obtain N.
Two edge positions corresponding to the rising edge and the falling edge of the RZI code data are detected to generate a binarized pulse.

Further, as a third conventional example thereof, there is a reproduction signal processing device disclosed in Japanese Patent Laid-Open No. 2-137128. This is because the reproduction signal from the information recording medium is second-order differentiated, and the zero-cross comparator of the second-order differentiated signal is detected by the zero-cross comparator of the binarization circuit to obtain 2
It is the one that is digitized.

[0006]

However, in the conventional mark edge recording method as described above, when data is recorded on the disc, the length becomes different from the actual write pulse due to the influence of the heat conduction of the disc. Moreover, the mark shape becomes irregular. This phenomenon becomes more remarkable in an information recording medium having a high thermal conductivity such as a magneto-optical disk, and as a result, in the conventional binarization method, two edge positions corresponding to the rising edge and the falling edge of NRZI code data are generated. Data cannot be detected correctly and a data playback error occurs.

Specifically, according to the example shown in FIG. 13, since the leading edge of the recording mark (c) is irregular in shape,
The edge position is detected at the rear position P ₁ from the original position P ₀ . In this case, especially the leading edge of the recording mark (c) is LD
Immediately after the irradiation of the (semiconductor laser) light is started, heat conduction to the recording layer of the disk is slow, resulting in irregular mark shape, resulting in a data reproduction error.

[0008]

According to a first aspect of the present invention, when a reproduced signal from an information recording medium on which NRZI code data is recorded is binarized, a rising edge of the NRZI code data is generated from the reproduced signal. A first threshold value for detecting a position and a second threshold value for detecting a falling edge position of the NRZI code data are set, and the first threshold value and the second threshold value are set based on the first threshold value and the second threshold value. The reproduction signal from the information recording medium is binarized.

According to the second aspect of the present invention, the reproduction signal from the information recording medium on which the NRZI code data is recorded and the first threshold value for detecting the rising edge position of the NRZI code data from the reproduction signal are input. And a second comparator to which the second threshold for detecting the falling edge position of the NRZI code data and the reproduction signal are input.
A binarization pulse generating means for generating a binarization pulse of the reproduction signal from the information recording medium based on each output signal of the comparator and the second comparator is provided.

According to a third aspect of the present invention, a reproduction signal from the information recording medium on which the NRZI code data is recorded, and a first threshold value for detecting the rising edge position of the NRZI code data from the reproduction signal or the above-mentioned first threshold value. A second threshold value for detecting the falling edge position of the NRZI code data is input, and it has a hysteresis characteristic and the hysteresis width is at or near the difference between the first threshold value and the second threshold value. A hysteresis comparator set to a value is provided, and a binarization pulse generation means for generating a binarization pulse of the reproduction signal from the information recording medium based on the output signal of the hysteresis comparator is provided.

According to a fourth aspect of the invention, in the second aspect of the invention, there is provided threshold tracking setting means for setting the first threshold and the second threshold in accordance with the envelope of the reproduction signal from the information recording medium. Provided.

According to a fifth aspect of the invention, in the first aspect of the invention, predetermined test data is recorded in an unused area of the test area or the data recording area provided on the information recording medium, and a reproduction signal of this test data is recorded. From the above, a first threshold value for detecting the rising edge position of the NRZI code data and a second threshold value for detecting the falling edge position of the NRZI code data are set to predetermined initial values, and Reproduction data is detected by generating a binarized pulse from the reproduction signal, a verify check of the test data and the reproduction data is executed, and as a result of this verification check, the data reproduction error does not occur. The reproduction data is detected while the value is variably set, and the verification check is repeatedly performed, thereby making it possible to obtain the first threshold value. And to perform the detection and setting of the optimum value of the second threshold.

According to a sixth aspect of the invention, in the fifth aspect of the invention, when the reproduction data is detected by generating a binarized pulse from the reproduction signal of the test data recorded on the information recording medium, The reproduction data is detected while the phase of the data discrimination window is shifted back and forth by a predetermined amount.

According to a seventh aspect of the invention, in the second aspect of the invention, the first threshold value input to the first comparator is selected one by one from among a plurality of set values based on the select command of the CPU. And a first multiplexer that is set based on a select command from the CPU, and sets a second threshold value, which is input to the second comparator, from among a plurality of setting values to 1
A second multiplexer for selecting and setting each one is provided.

According to an eighth aspect of the present invention, in the second aspect of the present invention, the first D / A converter that variably sets the first threshold value one by one based on the setting data of the CPU and the setting data of the CPU. Based on this, a second D / A converter that variably sets the second threshold value one by one is provided.

According to the invention of claim 9, claim 5 or 6
In the invention described above, the initial values of the first threshold value and the second threshold value are recorded in the designated area of the information recording medium.

According to a tenth aspect of the invention, in the invention of the fifth or sixth aspect, the optimum values of the first threshold value and the second threshold value are recorded in a designated area of the information recording medium, and the next threshold value is detected. Used as the initial value for the setting operation.

According to an eleventh aspect of the present invention, in the fifth or sixth aspect of the invention, the operation of detecting and setting the optimum values of the first threshold value and the second threshold value is performed when the power source of the drive device main body is turned on or idle. Executed when the state.

[0019]

According to the first aspect of the invention, the recording mark shape is obtained by detecting the rising edge position of the NRZI code data with the first threshold value and detecting the falling edge position of the NRZI code data with the second threshold value. It is possible to generate a binarized pulse at a position that should be originally detected even if there is an irregularity in the position, and it is possible to secure a sufficient window margin for data detection and to reliably reproduce recorded data. Becomes

According to the second aspect of the invention, the first comparator detects the rising edge position of the NRZI code data using the first threshold value, and the second comparator uses the second threshold value to detect the rising edge of the NRZI code data. Even if the recording mark shape is irregular, the first comparator and the second comparator detect the falling edge position and generate the binarized pulse by the binarized pulse generator based on the output signals of these comparators. It becomes possible to generate a binarized pulse at a position to be originally detected with an extremely simple circuit configuration with a comparator.

According to the third aspect of the invention, the hysteresis comparator detects the rising edge position and the falling edge position of the NRZI code data, and binarizes the binarized pulse by the binarizing pulse generating means based on the output signal of the hysteresis comparator. By generating the pulse, even if the recording mark shape is irregular, the binarized pulse can be generated at the position to be originally detected by the extremely simple circuit configuration of only the hysteresis comparator.

In the invention of claim 4, for example,
When data is recorded with a modulation code that does not have a DC-free characteristic such as (2,7,1,2) RLL or (1,7,2,3) RLL, the reproduction signal envelope has a low frequency. Therefore, by setting the first threshold value and the second threshold value by following the envelope of the reproduction signal by the threshold tracking setting means, (2,7,1,2) RLL and (1,7, 2,3) D like RLL
Even when data is recorded with a modulation code that does not have the C-free characteristic, a binarized pulse can be generated at a position where it should be detected even if the recording mark shape is irregular.

According to the invention of claim 5, it is possible to prevent the change of the type of the information recording medium and the change with time of the information recording medium from the first.
By detecting and setting the optimum value while varying the threshold value of 1 and the second threshold value, the binarized pulse can always be generated at the position that should be originally detected.

According to the sixth aspect of the invention, since the reproduction data is detected while shifting the phase of the data discrimination window by a predetermined amount back and forth, the first threshold value is provided near the center of the data discrimination window. It is possible to detect and set the optimum value of the second threshold value and the second threshold value, and it is possible to more reliably reproduce the recorded data.

In the seventh aspect of the invention, the optimum value can be detected and set while varying the first threshold value and the second threshold value with an extremely simple circuit configuration of the first multiplexer and the second multiplexer. Will be things.

According to the invention of claim 8, the first D /
With the extremely simple circuit configuration of the A converter and the second D / A converter, the optimum value can be detected and set while varying the first threshold value and the second threshold value.

In the invention described in claim 9, a value suitable for the type and various characteristics of the information recording medium can be used as an initial value when detecting and setting the optimum values of the first threshold value and the second threshold value. Will be things.

In the tenth aspect of the invention, when the next optimum value of the first threshold value and the second threshold value is detected and set, the optimum value before the first threshold value and the second threshold value is detected. By adopting the latest data of 1 as the initial value, the time required for detecting and setting the next optimum value of the first threshold value and the second threshold value can be shortened.

According to an eleventh aspect of the present invention, the operation of detecting and setting the optimum values of the first threshold value and the second threshold value is performed when the power source of the drive device main body is turned on or before data recording. Since it is executed when the device body is in the idle state, it is possible to detect and set the optimum values of the first threshold value and the second threshold value without interfering with other operations of the drive device body. ..

[0030]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the invention described in claims 1 and 2 is shown in FIG.
2 will be described with reference to FIG. FIG. 1 shows the circuit configuration of the present embodiment. Reproduction from an information recording medium (not shown) (not shown below) in which NRZI code data (b) is recorded in the input stage by the mark edge recording method. The first comparator (CP1) 5 to which the signal (d) is input to one input, and the second comparator (CP1)
2) 6 and are provided. A first threshold Th1 for detecting the rising edge position of the NRZI code data (b) of the reproduction signal (d) is input to the other input of the first comparator 5, and the other of the second comparators is input. A second threshold value Th2 for detecting the falling edge position of the NRZI code data (b) is input to the input of. These thresholds Th1 and Th2 are set independently in advance according to various characteristics such as the thermal conductivity of the disk used. Further, a binarization pulse generation means 7 is provided at the subsequent stage of the comparators 5 and 6. The binarized pulse generation means 7 is a first edge detector (E) connected to the output side of the first comparator 5.
D1) 8, a second edge detector (ED2) 9 connected to the output side of the second comparator 6, and an OR gate 10 having the outputs of these edge detectors 8 and 9 as inputs. ing.

The binary pulse generation process of this embodiment having such a configuration will be described with reference to FIG. The reproduction signal (d) corresponding to the recording mark (c) from the disc in which the recording data (a) is recorded as the NRZI code data (b) is detected by the first comparator 5 at the rising edge position of the NRZI code data (b). The first output pulse (e) is obtained by being compared with the first threshold value Th1 for detection, while the second comparator 6 is used for detecting the falling edge position of the NRZI code data (b).
And the second output pulse (f) is obtained. The output pulses (e) and (f) of these comparators 5 and 6 are input to the edge detectors 8 and 9, respectively, and the rising edges of the output pulses (e) and (f) are extracted to output the output pulse (g ), (H) are obtained. These output pulses (g) and (h) are input to the OR gate 10, and the detection pulse of the rising edge position and the falling edge position of the NRZI code data (b), that is, the binarized pulse (i) is generated. Taken out.

As described above, in this embodiment, the NRZI is used according to various characteristics such as the thermal conductivity of the disk used.
Since the first threshold value Th1 and the second threshold value Th2 for detecting the rising edge position and the falling edge position of the code data (b) can be independently set,
Even for a disc in which only the leading edge of the recording mark (c) has an irregular shape, the first threshold Th1 for detecting the rising edge position of the NRZI code data (b) is corrected and set in advance. As a result, it becomes possible to generate the binarized pulse (i) at the position that should be originally detected with the extremely simple circuit configuration of the first comparator 5 and the second comparator 6. As a result, it is possible to secure a sufficient window margin for data detection, and it is possible to reliably reproduce the recorded data (a).

Next, an embodiment of the invention described in claim 3 will be described with reference to FIGS. 3 and 4. The same parts as those described in FIGS. 1 and 2 are designated by the same reference numerals, and the description thereof will be omitted. FIG. 3 shows the circuit configuration of this embodiment.
The reproduction signal (d) from the disc and the preset first
The threshold value Th1 (or the second threshold value Th2) is input to the hysteresis comparator 11 having the hysteresis characteristic H. The hysteresis width of the hysteresis comparator 11 is set in advance to a difference value Thdif (or a value in the vicinity thereof) between the first threshold Th1 and the second threshold Th2. Further, an edge detector 12 as a binarized pulse generating means is connected to the output side of the hysteresis comparator 11.

The binary pulse generation process of this embodiment having such a configuration will be described with reference to FIG. The reproduction signal (d) corresponding to the recording mark (c) from the disc in which the recording data (a) is recorded as the NRZI code data (b) is input to the hysteresis comparator 11 having the hysteresis characteristic H, and first, the first It is compared with a threshold Th1 and then with a second threshold Th2 to obtain the output pulse (e). This hysteresis comparator 1
The output pulse (e) of 1 is input to the edge detector 12,
The edge detector 12 detects the rising edge position and the falling edge position of the output pulse (e). Thereby, the detection pulse of the rising edge position and the falling edge position of the NRZI code data (b), that is, the binarized pulse (f) is generated and taken out.

As described above, in the present embodiment, even if the recording mark (c) has an irregular shape, the threshold value Th1 of the hysteresis comparator 11 depends on various characteristics such as thermal conductivity of the used disk. By correcting and setting Th2 and the hysteresis width Thdif in advance, it becomes possible to generate the binarized pulse (f) at a position that should be originally detected with an extremely simple circuit configuration of only the hysteresis comparator 11. Further, it is possible to secure a sufficient window margin for data detection, and it is possible to reliably reproduce the recorded data (a).

Next, an embodiment of the invention described in claim 4 will be described with reference to FIGS. The same parts as those described in FIG. 1 are designated by the same reference numerals, and the description thereof will be omitted. In the present embodiment, for example, (2,7,1,2) RLL or (1,7,
2,3) When data is recorded using a modulation code that does not have a DC-free characteristic such as RLL, the envelope of the reproduction signal fluctuates at a low frequency, as shown in FIG.
As shown in FIG. 5, in addition to the configuration of the embodiment shown in FIG. 1, a first threshold value T is set on the input side of the first comparator 5 and the second comparator 6 following the envelope of the reproduction signal.
An auto slicer 13 as a threshold follow-up setting means for setting h1 and the second threshold Th2 is provided.

In this case, (2,7,1,2) RLL and (1,7,2,3) R
Data is recorded on the disc by a modulation code that does not have a DC-free characteristic such as LL, and as shown in FIG. 6, even if the envelope of the reproduction signal fluctuates at a low frequency, the auto slicer 13 A first threshold Th1 and a second threshold Th2 for detecting the rising edge position and the falling edge position of the NRZI code data following the envelope are set. In the example shown in FIG.
This can be implemented by using a first-order or second-order low-pass filter as the auto slicer 13.

As described above, (2,7,1,2) RLL and (1,7,
2,3) Even when data is recorded by a modulation code that does not have a DC-free characteristic such as RLL, only the leading edge of the recording mark is the same as in the embodiment shown in FIGS. 1 to 4. It is possible to generate a binarized pulse at a position that should be originally detected with respect to a disk having an irregular shape. Moreover, the window margin for data detection can be sufficiently secured, and the recorded data can be surely reproduced.

Next, an embodiment of the invention described in claims 5 and 7 will be described with reference to FIGS. 7 and 8. The same parts as those described in FIG. 1 are designated by the same reference numerals, and the description thereof will be omitted. In addition to the configuration of the above-described embodiment of FIG. 1 so that the threshold can be changed, the present embodiment has first thresholds Th1 and N1 for detecting the rising edge position of the NRZI code data.
A learning algorithm for detecting and setting an optimum value by varying the second threshold Th2 for detecting the falling edge position of the RZI code data is used. That is, as a learning algorithm, as shown in FIG.
The first multiplexer 15 by the select signals S ₁ of U14 to select the first threshold Th1 inputted from the threshold X1~Xn the first comparator 5 one by 1 (MUX
1), and a second multiplexer (MUX2) 16 to select the second threshold value Th2 which is input from the threshold Y1~Yn the second comparator 6 one is provided by a select signal S ₂ of the CPU14 There is.

In such a configuration, the first embodiment of the present embodiment
A learning algorithm for detecting and setting optimum values of the threshold value Th1 and the second threshold value Th2 will be described with reference to FIG. First, after the test data is recorded in a test area provided on the disc or an unused area of the data recording area, N
A first threshold Th1 for detecting the rising edge position of the RZI code data and a second threshold Th2 for detecting the falling edge position of the NRZI code data are set to predetermined initial values. Then, the binarized pulse is detected from the reproduction signal of the test data recorded on the disc,
The CPU 14 executes a verify check as to whether or not the data has been reproduced correctly. As a result, when a data reproduction error occurs, one or both initial values of the first threshold Th1 and the second threshold Th2 are changed,
Again, the binarized pulse is detected from the reproduced signal of the recorded test data, and the CPU 14 executes the verify check as to whether or not the data reproduction is correctly performed. The above operation is repeatedly executed until the data reproduction error disappears, and the optimum values of the first threshold Th1 and the second threshold Th2 are detected and set.

As described above, in this embodiment, the learning algorithm is executed by the extremely simple circuit configuration of the first multiplexer 15 and the second multiplexer 16, so that the first threshold Th1 and the second threshold Th2 are set. It is possible to detect and set the optimum value of. In addition, the first threshold Th1 is also set for the type of the disc and the change over time of the disc.
And the second threshold Th2 while varying these thresholds Th
By detecting and setting the optimum values of 1 and Th2, the binarized pulse can always be generated at the position where it should be originally detected.

Next, an embodiment of the invention described in claims 5 and 8 will be described with reference to FIGS. 8 and 9. The same parts as those described in FIG. 1 are designated by the same reference numerals, and the description thereof will be omitted. In this embodiment, similar to the embodiment shown in FIG. 7, a first threshold Th1 for detecting the rising edge position of the NRZI code data and a second threshold value Th1 for detecting the falling edge position of the NRZI code data. A learning algorithm for detecting and setting an optimum value while varying the threshold value Th2 is used. That is, in the present embodiment, as a learning algorithm, as shown in FIG. 9, the first D / A converter 17 that varies the first threshold Th1 input to the first comparator 5 according to the setting data D ₁ from the CPU 14 is used. And a second D / A converter 18 for varying the second threshold value Th2 input to the second comparator 6 according to the setting data D ₂ from the CPU 14.

Also in this case, the D / A converters 17, 1
With the extremely simple circuit configuration of FIG. 8, by changing the first threshold value Th1 and the second threshold value Th2 according to the learning algorithm shown in FIG. 8 as in the embodiment shown in FIG. It is possible to detect and set the optimum values of Th1 and Th2. In addition, the binarized pulse can always be generated at the position that should be detected, regardless of the type of the disc or the change over time of the disc.

Next, an embodiment of the invention described in claims 6, 9, 10 and 11 will be described with reference to FIGS. The same parts as those described with reference to FIGS. 7 to 9 are designated by the same reference numerals, and the description thereof will be omitted. This embodiment is the same as the embodiment shown in FIGS.
The data discrimination window generated from the data PLL has a function of executing a learning algorithm while shifting the window for data discrimination back and forth. That is, when the reproduced data is detected by generating a binarized pulse from the reproduced signal of the test data recorded on the disc, the reproduced data is detected while shifting the phase of the data discrimination window by a predetermined amount back and forth. It was done. However, the first threshold Th1 in the learning algorithm
The initial values of the second threshold Th2 and the second threshold Th2 are recorded in a designated area of the disc to be used (or stored in the CPU).

The operation of the learning algorithm of the present embodiment having such a configuration will be described with reference to FIGS. 10 and 11 based on the flowchart of FIG. First, after the test data is recorded in the designated area of the disc, the first
Threshold value Th1 and second threshold value Th2 are set to predetermined initial values. Then, the record data recorded on the disk is reproduced while shifting the data discrimination window forward and backward, and the CPU 14 performs a verify check as to whether or not the data is reproduced correctly. As a result of this verify check, when a data reproduction error as shown in FIG. 10 occurs, the first threshold Th1 and the second threshold T
One or both of the initial values with h2 are changed, and again,
The test data recorded is reproduced while shifting the data discrimination window back and forth, and a verify check is performed to determine whether or not the data reproduction was performed correctly. The above operation is repeatedly executed until the data reproduction error disappears, and as shown in FIG. 11, if the optimum values of the thresholds Th1 and Th2 are set near the center of the data discrimination window, the shift of the data discrimination window is stopped. Then, the operation of the learning algorithm is ended.

Here, in the illustrated example of FIG. 10, in the binarized pulse (b), the pulse A on the side corresponding to the rising edge position of the NRZI code data is detected at the Pa position behind the position where it should be originally detected. As a result, a data reproduction error has occurred, and the pulse B on the side corresponding to the falling edge position of the NRZI code data is detected at the Pb position and no data reproduction error has occurred. Therefore, in the illustrated example of FIG. 11, the first threshold Th1 is varied by a learning algorithm to detect the pulse A at the front Pa ′ position and eliminate the data reproduction error.

As described above, in this embodiment, it becomes possible to detect and set the optimum values of the first threshold value Th1 and the second threshold value Th2 near the center of the data discrimination window, and to record more reliably. The data can be reproduced. Moreover, since the first threshold value Th1 and the second threshold value Th2 are recorded in the designated area of the disc, a value suitable for the type and various characteristics of the disc is set when the optimum values of the threshold values Th1 and Th2 are detected and set. It can be used as an initial value.

The latest data of the optimum values of the first threshold value Th1 and the second threshold value Th2 obtained by the learning algorithm is used as the first threshold value Th by the next learning algorithm.
By adopting as the initial value for the optimum value detection / setting operation of 1 and the second threshold value Th2, the time required for the optimum value detection / setting operation of the threshold values Th1 and Th2 by the next learning algorithm is shortened. You will get it.

Further, the operation of detecting and setting the optimum values of the first threshold value Th1 and the second threshold value Th2 by the learning algorithm is performed when the power source of the drive device main body is turned on or before the data is recorded. If it is executed in the idle state, the optimum values of the threshold values Th1 and Th2 can be detected and set without interfering with other operations of the drive apparatus main body.

[0050]

According to the first aspect of the invention, when the reproduced signal from the information recording medium on which the NRZI code data is recorded is binarized, the rising edge position of the NRZI code data is detected from the reproduced signal. A first threshold for
A second threshold value for detecting the falling edge position of the NRZI code data is set, and the first threshold value and the second threshold value are set.
Since the reproduction signal from the information recording medium is binarized on the basis of the threshold value, the binarization pulse should be generated at a position that should be originally detected even if the recording mark shape is irregular. In addition, the window margin for data detection can be sufficiently secured, and the recorded data can be surely reproduced.

According to a second aspect of the present invention, a reproduction signal from the information recording medium on which the NRZI code data is recorded and a first threshold value for detecting the rising edge position of the NRZI code data from the reproduction signal are input. And a second comparator to which the reproduction signal is input and a second threshold value for detecting the falling edge position of the NRZI code data is provided. The first comparator and the second comparator are provided. Binary pulse generation means for generating a binarized pulse of the reproduction signal from the information recording medium on the basis of each output signal of NRZI code data is used by the first comparator using the first threshold value. The edge position is detected, and the falling edge position of the NRZI code data is detected by the second comparator using the second threshold value. Since the binarized pulse generating means generates the binarized pulse based on each output pulse of these comparators, even if the recording mark shape is irregular, the first comparator and the second comparator are extremely simple. With such a circuit configuration, a binarized pulse can be generated at a position that should be originally detected.

According to a third aspect of the present invention, a reproduction signal from the information recording medium on which the NRZI code data is recorded, and a first threshold value for detecting the rising edge position of the NRZI code data from the reproduction signal, or the first threshold value is used. A second threshold value for detecting the falling edge position of the NRZI code data is input, and it has a hysteresis characteristic and the hysteresis width is at or near the difference between the first threshold value and the second threshold value. A hysteresis comparator set to a value is provided, and binarization pulse generation means for generating a binarization pulse of the reproduction signal from the information recording medium based on the output signal of the hysteresis comparator is provided, and the NRZI code is generated by the hysteresis comparator. The rising edge position and falling edge position of the data are detected and this hysteresis comparator is used. Since so as to generate a binary pulse binarization pulse generating means based on the output signal of the data,
Even if the recording mark shape is irregular, the binarized pulse can be generated at the position to be originally detected with an extremely simple circuit configuration including only the hysteresis comparator.

According to a fourth aspect of the present invention, in the second aspect of the invention, there is provided threshold follow-up setting means for setting the first threshold and the second threshold following the envelope of the reproduction signal from the information recording medium. For example, (2,7,1,2) RLL or (1,7,2,
3) When data is recorded with a modulation code that does not have a DC-free characteristic such as RLL, the envelope of the reproduced signal fluctuates at a low frequency, so the threshold follow-up setting means follows the envelope of the reproduced signal. By setting the first threshold and the second threshold, (2,7,1,2) RLL and (1,
Even if data is recorded with a modulation code that does not have DC-free characteristics such as 7,2,3) RLL, even if there is an irregular recording mark shape, it is binarized at the position where it should be detected. A pulse can be generated.

According to a fifth aspect of the invention, in the first aspect of the invention, predetermined test data is recorded in an unused area of the test area or the data recording area provided on the information recording medium, and a reproduction signal of this test data is recorded. To a first threshold value for detecting the rising edge position of the NRZI code data and a second threshold value for detecting the falling edge position of the NRZI code data are set to predetermined initial values, and Reproduction data is detected by generating a binarized pulse from the reproduction signal, a verify check of the test data and the reproduction data is executed, and as a result of this verification check, the initial value is repeated until no data reproduction error occurs. By repeating the verify check by detecting the reproduced data while variably setting the first threshold value and the second threshold value. Since the optimum value and the optimum value are detected and set, the optimum value can be set while varying the first threshold value and the second threshold value with respect to the type of the information recording medium and the change over time of the information recording medium. It can be detected and set, and a binarized pulse can always be generated at a position where it should be originally detected.

According to a sixth aspect of the invention, in the fifth aspect of the invention, when the reproduced data is detected by generating a binarized pulse from the reproduced signal of the test data recorded on the information recording medium, Since the reproduction data is detected while shifting the phase of the data discrimination window by a predetermined amount back and forth, the optimum values of the first threshold value and the second threshold value are detected and set near the center of the data discrimination window. Therefore, the recorded data can be reproduced more reliably.

According to a seventh aspect of the present invention, in the second aspect of the present invention, the first threshold value input to the first comparator is selected one by one from among a plurality of set values based on the select command of the CPU. And a first multiplexer that is set based on a select command from the CPU, and sets a second threshold value, which is input to the second comparator, from among a plurality of setting values to 1
Since the second multiplexer for selecting and setting each one is provided, the detection of the optimum value while varying the first threshold value and the second threshold value with an extremely simple circuit configuration of the first multiplexer and the second multiplexer. It is something that can be set.

According to an eighth aspect of the present invention, in the second aspect of the present invention, the first D / A converter that variably sets the first threshold value one by one based on the setting data of the CPU and the setting data of the CPU. Since the second D / A converter that variably sets the second threshold value one by one based on the
The optimum value can be detected and set while varying the first threshold value and the second threshold value with an extremely simple circuit configuration of the D / A converter and the second D / A converter.

According to a ninth aspect of the invention, in the fifth or sixth aspect of the invention, the initial values of the first threshold value and the second threshold value are recorded in a designated area of the information recording medium. A value suitable for the type and various characteristics of the recording medium can be used as an initial value when the optimum values of the first threshold value and the second threshold value are detected and set.

The invention according to claim 10 is the invention according to claim 5 or 6.
In the invention described above, the optimum values of the first threshold value and the second threshold value are recorded in the designated area of the information recording medium and used as the initial values for the next threshold value detection / setting operation. It is possible to shorten the time required for detecting and setting the next optimum value of the threshold value of 1 and the second threshold value.

The invention according to claim 11 is the invention according to claim 5 or 6.
In the invention described above, the operation of detecting and setting the optimum values of the first threshold value and the second threshold value is executed when the power source of the drive device main body is started up or in the idle state. The optimum values of the first threshold value and the second threshold value can be detected and set without hindering the operation.

[Brief description of drawings]

FIG. 1 shows an embodiment of the invention according to claims 1 and 2
It is a circuit diagram of a quantizer.

FIG. 2 is a waveform diagram showing signals of respective parts in FIG.

FIG. 3 is a circuit diagram of a binarizing device showing an embodiment of the invention described in claim 3.

FIG. 4 is a waveform diagram showing signals of respective parts of FIG.

FIG. 5 is a circuit diagram of a binarizing device showing an embodiment of the invention described in claim 4.

FIG. 6 is a waveform diagram showing a state of an envelope of a reproduced signal.

FIG. 7 shows an embodiment of the invention described in claims 5 and 7
It is a circuit diagram of a quantizer.

FIG. 8 is a flowchart showing a procedure for detecting and setting a threshold value by a learning algorithm.

FIG. 9 shows an embodiment of the invention described in claims 5 and 8;
It is a circuit diagram of a quantizer.

FIG. 10 is a waveform diagram showing an embodiment of the invention described in claims 6, 9, 10 and 11.

FIG. 11 is a waveform diagram showing an embodiment of the invention described in claims 6, 9, 10 and 11.

FIG. 12 is a flowchart showing a procedure of detecting and setting a threshold value by the learning algorithm of FIGS. 10 and 11.

FIG. 13 is a waveform diagram showing a conventional binarization process.

FIG. 14 is a circuit diagram of a binarizing device showing a first conventional example.

FIG. 15 is a circuit diagram of a binarizing device showing a second conventional example.

[Explanation of symbols]

 5 1st Comparator 6 2nd Comparator 7, 12 Binary pulse generation means 11 Hysteresis comparator 13 Threshold tracking setting means 14 CPU 15 1st multiplexer 16 2nd multiplexer 17 1st D / A converter 18 2nd D / A converter H Hysteresis characteristic Th1 first threshold Th2 second threshold

Claims (11)

[Claims] 1. A first threshold value for detecting a rising edge position of the NRZI code data from the reproduction signal when binarizing a reproduction signal from an information recording medium on which NRZI code data is recorded, A second threshold value for detecting the falling edge position of the NRZI code data is set, and the reproduction signal from the information recording medium is binarized based on the first threshold value and the second threshold value. The binarization method is characterized in that 2. A reproduction signal from an information recording medium on which NRZI code data is recorded and the NRZ from the reproduction signal.
A first comparator to which a first threshold value for detecting the rising edge position of the I code data is input is provided, and a second threshold value for detecting the falling edge position of the NRZI code data and the reproduction signal are provided. A binarized pulse generating means for generating a binarized pulse of the reproduction signal from the information recording medium on the basis of output signals of the first comparator and the second comparator. A binarization device characterized by being provided with. 3. A reproduction signal from an information recording medium on which NRZI code data is recorded, and the NR from the reproduction signal.
A first threshold value for detecting the rising edge position of the ZI code data or a second threshold value for detecting the falling edge position of the NRZI code data is input and has a hysteresis characteristic and its hysteresis width. Is provided with a hysteresis comparator set to a difference between the first threshold value and the second threshold value or a value in the vicinity thereof, and binarizes the reproduction signal from the information recording medium based on the output signal of the hysteresis comparator. A binarizing device comprising a binarizing pulse generating means for generating a pulse. 4. The binary value according to claim 2, further comprising threshold tracking setting means for setting the first threshold value and the second threshold value in accordance with the envelope of the reproduction signal from the information recording medium. Device. 5. A first area for recording predetermined test data in an unused area of a test area or a data recording area provided on an information recording medium, and detecting a rising edge position of NRZI code data from a reproduced signal of the test data. By setting a threshold value of 1 and a second threshold value for detecting the falling edge position of the NRZI code data to predetermined initial values, and generating a binarized pulse from the reproduction signal of the test data. Detects the reproduced data, executes a verify check of the test data and the reproduced data, and as a result of this verify check, detects the reproduced data while setting the initial value variably until the occurrence of the data reproduction error disappears, and performs the verify check. By repeating the above steps, the optimum values of the first threshold value and the second threshold value are detected and set. The binarization method according to claim 1, wherein: 6. When detecting reproduced data by generating a binarized pulse from a reproduced signal of test data recorded on an information recording medium, while shifting a phase of a data discrimination window by a predetermined amount back and forth. The binarization method according to claim 5, wherein the reproduction data is detected. 7. A first multiplexer for selecting and setting a first threshold value input to a first comparator one by one from a plurality of set values based on a select command of the CPU, and a select command of the CPU. Based on the set value, the second threshold value input to the second comparator is set to 1
3. The binarizing device according to claim 2, further comprising a second multiplexer for selecting and setting each one. 8. A first D / A converter that variably sets a first threshold value one by one based on CPU setting data, and a first D / A converter that variably sets a second threshold value one by one based on the CPU setting data. The binarization device according to claim 2, further comprising a 2D / A converter. 9. The binarizing method according to claim 5, wherein initial values of the first threshold value and the second threshold value are recorded in a designated area of the information recording medium. 10. The optimum value of the first threshold value and the second threshold value is recorded in a designated area of an information recording medium and used as an initial value for the next threshold value detection / setting operation. The binarization method according to claim 5 or 6. 11. An optimum value detection / setting operation for the first threshold value and the second threshold value is executed when the drive device main body is powered on or in an idle state. The binarization method according to item 6.