JP2013041635A - Data recording/reproducing device and degree of modulation detecting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a data recording/reproducing device with a small circuit scale and low power consumption.SOLUTION: A data recording/reproducing device comprises: an amplitude adjusting section 10 for generating a 4-ch addition signal 11 that is suitable for detection of OPC information; an adder 13 for generating an RF signal 14 that is suitable for reproduction of data; a gate signal generating section 16 for generating a gate signal 17; a signal selecting section 15 that selects and outputs either the RF signal 14 or the 4-ch addition signal 11 on the basis of the gate signal 17; a reproducing signal processing section 82 that performs demodulation of the data by converting an output signal from the signal selecting section 15 to a digital RF signal 33; an OPC information detecting section 20 for generating degree of modulation information 27 and asymmetry information 28 from the digital RF signal 33; and a recording power adjusting section 69 for adjusting optimum laser recording power on the basis of the degree of modulation information 27 and the asymmetry information 28.

Description

  The present invention relates to a data recording / reproducing apparatus that records digital data on an optical recording medium and reproduces digital data from the optical recording medium, and a modulation degree detecting apparatus thereof.

  More specifically, it has a function for detecting the degree of modulation and asymmetry of a recorded signal necessary for optimum recording power control (hereinafter referred to as “OPC”), which is adjustment of laser recording power during recording. The present invention relates to accompanying data recording / reproducing technology.

  As a method for recording digital data on an optical disk medium as an information recording medium, it can be found in a compact disk (Compact Disc (registered trademark); hereinafter referred to as “CD”) and a digital versatile disk (hereinafter referred to as “DVD”). As described above, a method of making the recording density on the recording medium uniform while keeping the linear velocity constant is often used. In recent years, not only read-only optical discs but also DVD-Recordables (hereinafter referred to as “DVD-R”) that can be written once, and rewritable DVD-ReWriteables (hereinafter referred to as “DVD-RW”). Furthermore, a Blu-ray Disc-Recordable (hereinafter referred to as “BD-R”) and a Blu-ray Disc-ReWriteable (hereinafter referred to as “BD-RE”) capable of recording a large amount of data, Attention has been paid.

  In order to record digital data on an optical disk medium, OPC for adjusting the laser recording power is required depending on the recording sensitivity of the disk film, the temperature, the difference in the recording state due to the laser wavelength variation, and the like. For example, the OPC performs test writing by allocating power to (power calibration area) PCA (Power Calibration Area) existing in the inner periphery of the optical disc medium, reads the recorded signal, and reflects the reflectance of the pit portion and the non-pit portion. The optimum power is determined according to the degree of modulation, which is an index indicating the difference between the two, and the asymmetry, which is an index indicating the asymmetry between the pit and non-pit portions.

  Here, in order to detect the modulation degree and asymmetry, it is necessary to obtain the peak value, bottom value, and average value from the reproduction signal. In order to detect asymmetry, a direct current component (Direct Current component, hereinafter, On the other hand, in order to detect the degree of modulation, a DC component is required. Therefore, when reproducing recorded data, an RF (Radio Frequency, hereinafter referred to as “RF”) signal transmitted for data reproduction (data demodulation) from an optical pickup that converts an optical signal into an electric signal is used. On the other hand, in data demodulation processing that performs AC (Active Current, hereinafter referred to as “AC”) coupling, offset control (offset cancellation), and automatic gain control (Auto Gain Control, hereinafter referred to as “AGC”). Since the DC component is lost or the amplitude information changes, it is difficult to detect the modulation degree. Therefore, there is a DC component used for a servo-related signal separately, and the amplitude information changes statically 4 Addition signal of 4 channels (hereinafter referred to as “4ch”) that receive the signals of the divided photodetectors. The peak value and the bottom value of the reproduction signal are extracted using a detection circuit, and the modulation degree is extracted from the source signal by an optical disk controller composed of a CPU (central processing unit) and software (program). (For example, refer to Patent Document 1).

  The conventional data recording / reproducing apparatus disclosed in Patent Document 1 has a configuration as shown in FIG. In FIG. 10, an optical recording medium 1 is an optical recording medium having a thin film of a phase change recording material, and tracks are formed in a spiral shape or a concentric shape at a predetermined interval. The optical recording medium rotation control unit 2 is a circuit that rotates the optical recording medium 1 at a predetermined linear velocity. When reading out digital data from the optical recording medium 1, the optical pickup 3 converts the reflected light from the optical spot into an electric signal and an actuator equipped with a laser generating unit 4 that scans the track with the light spot focused. A 4-division photo detector 5 and a 2-division photo detector 6 for detecting a tracking error signal and a push-pull signal are provided. The adder 7 and the adder 8 perform current-voltage conversion for converting the detection current output from the four-divided photodetector 5 into voltage, and add the components in the region parallel to the track direction. The adder 13 performs current-voltage conversion and addition for converting the detection current output from the two-divided photodetector 6 into a voltage.

  The OPC information detection unit 91 is an analog circuit for detecting OPC information, and includes amplitude and offset adjustment units 70 and 71, an addition signal detection unit 72, comparators 73 and 74, and D / A converters 75 and 76. , A peak detection unit 77, a bottom detection unit 78, and a modulation degree detection unit 79. The output signals from the adder 7 and the adder 8 are input to the amplitude & offset adjustment units 70 and 71, and after adjusting the amplitude and offset, are input to the addition signal detection unit 72, and voltage is added. The output signal from the addition signal detector 72 is input to the comparators 73 and 74 and then binarized based on the threshold values generated by the D / A converters 75 and 76. The output signals from the binarized comparators 73 and 74 are input to the peak detector 77 and the bottom detector 78. The peak detection unit 77 outputs the detected peak envelope information to the modulation degree detection unit 79 while controlling the D / A converter 75 to detect the peak envelope from the output signal from the addition signal detection unit 72. On the other hand, the bottom detection unit 78 outputs the detected bottom envelope information to the modulation degree detection unit 79 while controlling the D / A converter 76 so as to detect the bottom envelope from the output signal from the addition signal detection unit 72. The modulation degree detection unit 79 calculates and detects the modulation degree information 27, which is information necessary for OPC for optimally recording digital data on the optical recording medium 1, from the peak envelope information and the bottom envelope information. The modulation degree information 27 is transmitted to the optical disk controller 18.

  The optical disk controller 18 is a circuit composed of a CPU, software (program), and the like, and an appropriate recording power for recording on the optical recording medium 1 through the recording power adjustment unit 69 based on the obtained modulation degree information 27. To decide. The recording power adjusting unit 69 records data on the optical recording medium 1 through the laser generating unit 4 based on the recording power.

  On the other hand, in order to reproduce digital data, output signals from the adder 7, adder 8, and adder 13 are added by the RF signal generation unit 80, and the reproduction signal processing unit 92 is obtained as an RF signal (reproduction signal) 14. Is input. The reproduction signal processing unit 92 is a circuit that performs various signal processing on the input RF signal 14 and then performs A / D conversion and data demodulation. The reproduction signal processing unit 92 adjusts the reproduction signal amplitude and the first offset canceller 21. The unit 22, the equalizer 23, the A / D converter 12, the second offset canceller 24, and the data demodulation unit 25 are configured. The RF signal 14 is input to the first offset canceller 21 and adjusted to an offset level appropriate for the dynamic range of the A / D converter 12. The output signal from the first offset canceller 21 is input to the reproduction signal amplitude adjusting unit 22 and adjusted to an amplitude appropriate for the dynamic range of the A / D converter 12. The output signal from the reproduction signal amplitude adjusting unit 22 is input to the equalizer 23, where frequency characteristics are corrected and noise is removed. An output signal from the equalizer 23 is input to the A / D converter 12. The A / D converter 12 converts the analog signal into a digital RF signal 33 that is a multi-bit digital signal at the timing of the reproduction clock 32 generated from the data demodulator 25. The digital RF signal 33 is input to the second offset canceller 24, whereby the offset component (DC component) included in the digital RF signal 33 is reduced. The output signal from the second offset canceller 24 is input to the data demodulator 25, and a digital binarized signal 49 is generated. The digital binarized signal 49 is input to the optical disk controller 18, and then subjected to error correction processing and the like, and converted to digital data with no more errors.

  A series of processing for the RF signal 14 as follows: first offset canceller 21 → reproduced signal amplitude adjusting unit 22 → equalizer 23 → A / D converter 12 → second offset canceller 24 → data demodulating unit 25 → optical disk controller 18. By the operation of the reproduction signal processing system, the digital data recorded on the optical recording medium 1 can be reproduced.

International Publication No. 2008/035689

  However, in the conventional data recording / reproducing apparatus, since the OPC information detection unit 91 is an analog circuit, there is a problem that the circuit scale and power consumption increase.

  This is because the signal obtained by adding the 4ch signals used for the detection of the OPC information (4ch addition signal) should correspond to a signal equivalent to the signal corresponding to the RF signal, but the OPC information detection unit 91 and the reproduction signal processing This is because the OPC information detection unit 91 and the reproduction signal processing unit 92 need to be provided separately and independently because they perform different analog signal processing. That is, since the reproduction signal processing unit 92 for performing data demodulation needs to improve the accuracy of data demodulation, the A / D converter 12 performs AGC and offset control before AD conversion in the A / D converter 12. Effective use of the dynamic range. For this reason, the reproduction signal processing unit 92 lacks a DC component or changes amplitude information of the RF signal. On the other hand, for adjustment of laser recording power such as OPC (that is, when detecting OPC information), information such as modulation degree information obtained from DC components and accurate amplitude information is required. Therefore, modulation degree information or the like cannot be directly detected from the signal processed by the reproduction signal processing unit 92. For this reason, in the conventional data recording / reproducing apparatus, an analog circuit (OPC information detecting unit 91) having a function of detecting a peak value, a bottom value, and an average value independently of the reproduced signal processing unit 92. Therefore, it is disadvantageous in terms of circuit scale and power consumption.

  Here, when it is assumed that the analog signal processing in the OPC information detection unit 91 is processed in the reproduction signal processing unit 92, the asymmetry information has characteristics that do not depend on the DC component or the amplitude information, and thus can be detected. However, since the modulation degree information has characteristics depending on the DC component and the amplitude information, AGC (processing in the reproduction signal amplitude adjusting unit 22), offset control (processing in the first offset canceller 21), and the like are performed. Due to the presence, accurate estimation is difficult.

  Further, A / D conversion is performed with a DC component that can detect modulation degree information, OPC information is detected using digital data after A / D conversion, and after A / D conversion for data demodulation. However, in order to maintain the accuracy of the modulation degree information (that is, an analog signal having a DC component is converted into A / A). Since D conversion is performed), securing the dynamic range of the A / D converter and a large number of effective bits are required, which causes a problem that the circuit scale and power of the A / D converter increase.

  Therefore, an object of the present invention is to provide a data recording / reproducing apparatus and a modulation degree detecting apparatus with a small circuit scale and low power consumption.

  In order to solve the above-described conventional problems, the data recording / reproducing apparatus and the modulation degree detecting apparatus of the present invention have a function of selecting either an RF signal or a 4ch addition signal, for data demodulation and detection of OPC information. The two analog signal processes of pre-processing are performed in common with one system (reproduction signal processing unit). This eliminates the need for a dedicated analog circuit for performing pre-processing for detecting OPC information, thereby realizing a data recording / reproducing apparatus and modulation degree detecting apparatus with a small circuit scale and low power consumption.

  That is, one form of the data recording / reproducing apparatus of the present invention includes a four-divided photodetector that detects an optical signal divided into four by an optical recording medium by a track direction axis and a radial axis perpendicular to the track direction axis. Including an optical pickup, an addition signal detection unit that generates a signal corresponding to the addition result of the four-divided optical signals detected by the four-divided photodetector, and an amplitude of an output signal from the addition signal detection unit Select one of an amplitude adjustment unit, an RF signal generation unit that generates an RF signal as a reproduction signal from the output of the optical pickup, an output signal from the RF signal generation unit, and an output signal from the amplitude adjustment unit A gate signal generating unit for generating a gate signal for performing, and the RF signal generating unit based on the gate signal generated from the gate signal generating unit A signal selection unit that selects and outputs either the output signal from the output signal or the output signal from the amplitude adjustment unit, and performs data demodulation by converting the output signal from the signal selection unit into a multi-bit digital signal From the digital signal obtained by the reproduction signal processing unit and the reproduction signal processing unit, modulation degree information which is an index indicating the difference in reflectance between the pit portion and the non-pit portion in the optical recording medium, and the pit in the optical recording medium An optimal recording power control information detection unit that generates asymmetry information that is an index indicating asymmetry between the non-pit portion and the non-pit portion, a digital binarized signal after data demodulation output from the reproduction signal processing unit, and Recording power adjustment unit that adjusts the optimum laser recording power based on modulation degree information and asymmetry information that are output signals from the optimum recording power control information detection unit Equipped with a.

  As a result, preprocessing for detecting OPC information (analog signal processing) and data reproduction are performed by a common circuit (reproduction signal processing circuit). An analog circuit becomes unnecessary, and the circuit scale and power can be reduced. In general, even for circuits that perform the same signal processing, an analog circuit requires a large-area electronic component such as a capacitor, and therefore has a larger circuit scale than a digital circuit suitable for integration. As a result, power consumption increases.

  Here, as a more specific circuit configuration, the reproduction signal processing unit includes a first offset canceller that removes an offset component from the output signal from the signal selection unit, and an output from the first offset canceller. A reproduction signal amplitude adjustment unit that adjusts the amplitude of the signal, an equalizer that performs waveform shaping on the output signal from the reproduction signal amplitude adjustment unit, and an analog output signal from the equalizer that is converted into a multi-bit digital signal A An offset control unit that generates offset control information for controlling the first offset canceller from an output signal from the A / D converter and outputs the offset control information to the first offset canceller, and the A A gain control information for controlling the reproduction signal amplitude adjusting unit is generated from an output signal from the / D converter. From the amplitude control unit that outputs to the reproduction signal amplitude adjustment unit, the second offset canceller that removes an offset component from the output signal from the A / D converter, and the output signal from the second offset canceller, A data demodulator that performs data demodulation to generate a digital binarized signal and a reproduction clock indicating a clock component included in the reproduction signal, and the optimum recording power control information detection unit includes the A / D Using the output signal from the converter, the offset control information output from the offset control unit, and the gain control information output from the amplitude control unit, the output signal from the A / D converter The peak value, the bottom value, and the average value are obtained after reverse correction using the gain control information and the offset control information. The modulation level information and the asymmetry information are generated using the extracted peak value, bottom value, and average value, and the recording power adjustment unit is synchronized with the reproduction clock output from the data demodulation unit The optimum laser recording power is adjusted based on the digital binarized signal output from the data demodulator and the modulation degree information and asymmetry information from the optimum recording power control information detector. May be.

  Further, an optical disk controller that generates timing information for controlling the gate signal generation unit based on the digital binarized signal is provided, and the gate signal generation unit is based on the timing information output from the optical disk controller. Generating a gate signal capable of designating an arbitrary time interval, and causing the signal selection unit to select an output signal from the amplitude adjustment unit including a DC component based on the gate signal, and the first offset By holding the operations of the canceller, the reproduction signal amplitude adjusting unit, the second offset canceller, and the data demodulating unit, DC correction information and gain difference information are sent to the optimum recording power control information detecting unit. Preferably, the modulation degree information is generated by detection.

  Thereby, when the reproduction signal processing unit processes a signal suitable for detection of OPC information (output signal from the amplitude adjustment unit), the operations of the first offset canceller and the reproduction signal amplitude adjustment unit are held. Therefore, the optimum recording power control information detection unit can generate accurate modulation degree information and asymmetry information using a digital signal that has not lost the DC component and the amplitude information.

  Further, the optimum recording power control information detection unit outputs from the A / D converter based on gain control information output from the amplitude control unit when the gate signal is not output from the gate signal generation unit. An amplitude reverse correction unit that restores amplitude information by performing reverse correction on the output signal may be provided, and the optimum recording power control information detection unit outputs the gate signal from the gate signal generation unit. A DC reverse correction unit that restores a DC component by performing reverse correction on the output signal from the A / D converter based on the offset control information output from the offset control unit, if not Also good.

  As a result, even when data is being reproduced, after the DC component and amplitude information contained in the RF signal are restored to the output signal from the A / D converter, the output signal becomes OPC. Since it is used for information detection, it is possible to detect modulation degree information and asymmetry information simultaneously with data reproduction. Therefore, it is not necessary to perform data reproduction and pre-processing for detecting OPC information separately in two (two different time intervals), thereby shortening the learning time during OPC and the startup time of the apparatus. Is possible.

  Further, according to this configuration, since the A / D conversion is performed after applying the offset control and the gain control to the RF signal, the dynamic range and the bit width of the A / D converter can be effectively used. Become. That is, the problem that the circuit scale and power consumption of the A / D converter are sacrificed due to the combined use of data reproduction and preprocessing for detecting OPC information in the reproduction signal processing unit is avoided. .

  The present invention can be realized not only as such a data recording / reproducing apparatus but also from an optical recording medium to detect an optical signal divided into four by a track direction axis and a radial axis perpendicular to the track direction axis. Based on a signal from an optical pickup including a four-divided photodetector, the modulation degree information which is an index indicating the difference in reflectance between the pit portion and the non-pit portion in the optical recording medium, and the pit portion and the non-pit in the optical recording medium A modulation degree detection device that generates asymmetry information that is an index indicating the asymmetry of a unit, wherein the addition generates a signal corresponding to the addition result of the four-split optical signals detected by the four-split photodetector A signal detector, an amplitude adjuster for adjusting the amplitude of the output signal from the addition signal detector, and a reproduction signal from the output of the optical pickup An RF signal generation unit that generates all RF signals, a gate signal generation unit that generates a gate signal for selecting one of the output signal from the RF signal generation unit and the output signal from the amplitude adjustment unit, A signal selection unit that selects and outputs either an output signal from the RF signal generation unit or an output signal from the amplitude adjustment unit based on the gate signal generated from the gate signal generation unit; A reproduction signal processing unit that performs data demodulation by converting an output signal from the recording unit into a multi-bit digital signal, and a pit portion and a non-pit portion in the optical recording medium from the digital signal obtained by the reproduction signal processing unit Modulation degree information, which is an index indicating the difference in reflectance, and asymmetry information, which is an index indicating asymmetry between the pit portion and the non-pit portion in the optical recording medium, are generated It may be implemented as a modulation degree detecting apparatus and a proper recording power control information detecting section.

  Further, the present invention can be realized as a method using the processing units constituting these devices as steps, or as a program for causing a computer to execute the steps, or a computer-readable CD-ROM recording the program. It can also be realized as a non-temporary recording medium such as information, data, or a signal indicating the program. Needless to say, these programs, information, data, and signals can be distributed via a communication network such as the Internet.

  As described above, according to the data recording / reproducing apparatus and modulation degree detecting apparatus of the present invention, a dedicated analog circuit for detecting OPC information, which has been required in the past, is not required, and the circuit scale and power can be reduced. It becomes possible.

  In particular, when implemented using a semiconductor integrated circuit, it is possible to provide a data recording / reproducing apparatus and a modulation degree detecting apparatus with a small circuit scale and low power consumption.

The block diagram which shows the structure of the data recording / reproducing apparatus in embodiment of this invention, and a modulation degree detection apparatus The block diagram which shows the detailed structure of the optical pick-up of the data recording / reproducing apparatus The figure which showed the operation timing concerning the gate signal in the same data recording / reproducing apparatus The figure which showed the detection principle of the modulation degree information by the OPC information detection part of the data recording / reproducing apparatus Explanatory diagram of frequency characteristics of high-order ripple filter in equalizer of same data recording / reproducing device The block diagram which shows the detailed structure of the 2nd offset canceller of the data recording / reproducing apparatus The block diagram which shows the detailed structure of the phase-synchronization control part which the data demodulation part of the data recording / reproducing apparatus has The figure explaining operation | movement of the same phase synchronous control part Secondary digital low as one implementation example of the first LPF, the second LPF, the peak value averaging unit, the bottom value averaging unit, and the average value averaging unit constituting the OPC information detection unit of the data recording / reproducing apparatus. Block diagram showing the configuration of a band-pass filter Block diagram showing the configuration of a conventional data recording / reproducing apparatus

  Embodiments of a data recording / reproducing apparatus and a modulation degree detecting apparatus of the present invention will be described below in detail with reference to the drawings. Each of the embodiments described below shows a preferred specific example of the present invention. Circuit configurations, arrangement positions and connection forms of components, operations, operation timings, signal logic, signal waveforms, and the like shown in the following embodiments are merely examples, and are not intended to limit the present invention. The invention is limited only by the claims. Therefore, among the constituent elements in the following embodiments, constituent elements that are not described in the independent claims indicating the highest concept of the present invention are not necessarily required to achieve the object of the present invention. It will be described as constituting a preferred form.

  FIG. 1 is a block diagram showing a configuration of a data recording / reproducing apparatus according to an embodiment of the present invention. This data recording / reproducing apparatus includes, as main components, an optical pickup 3, an addition signal detection unit 9, an amplitude adjustment unit 10, an adder 13, a gate signal generation unit 16, a signal selection unit 15, and a reproduction. A signal processing unit 82, an OPC information detection unit 20, and a recording power adjustment unit 69 are provided.

  The optical pickup 3 is an assembly having a four-divided photodetector 5 for detecting an optical signal divided into four from the optical recording medium 1 by a track direction axis and a radial axis perpendicular to the track direction axis. The addition signal detection unit 9 is a circuit that generates a signal corresponding to the addition result of the four-divided optical signals detected by the four-divided photodetector 5. The amplitude adjustment unit 10 is a circuit that adjusts the amplitude of the signal output from the addition signal detection unit 9 to generate the 4ch addition signal 11. The adder 13 is a circuit (current / voltage converter) as an RF signal generation unit that generates an RF signal 14 as a reproduction signal from the output (detection current) of the optical pickup 3. The gate signal generation unit 16 is a circuit that generates a gate signal 17 for selecting one of the RF signal 14 output from the adder 13 and the 4ch addition signal 11 from the amplitude adjustment unit 10. The signal selection unit 15 selects either the RF signal 14 output from the adder 13 or the 4ch addition signal 11 output from the amplitude adjustment unit 10 based on the gate signal 17 generated from the gate signal generation unit 16. The output circuit. The reproduction signal processing unit 82 is a circuit that performs data demodulation by converting the output signal from the signal selection unit 15 into a multi-bit digital RF signal 33. The OPC information detection unit 20 uses the modulation degree information 27, which is an index indicating the difference in reflectance between the pit portion and the non-pit portion in the optical recording medium 1, and the optical recording from the digital RF signal 33 obtained by the reproduction signal processing unit 82. This is a digital circuit that generates asymmetry information 28, which is an index indicating the asymmetry between the pit portion and the non-pit portion in the medium. The recording power adjustment unit 69 is optimized based on the digital demodulated signal after data demodulation output from the reproduction signal processing unit 82 and the modulation degree information 27 and asymmetry information 28 output from the OPC information detection unit 20. This is a circuit for adjusting the laser recording power.

  Here, as a detailed configuration, the reproduction signal processing unit 82 includes a first offset canceller 21 that removes an offset component (DC component) from the output signal from the signal selection unit 15, and a first offset canceller 21. A reproduction signal amplitude adjusting unit 22 that adjusts the amplitude of the output signal, an equalizer 23 that performs waveform shaping on the output signal from the reproduction signal amplitude adjusting unit 22, and an analog output signal from the equalizer 23 as a multi-bit digital RF. Offset control information for controlling the first offset canceller 21 is generated from the A / D converter 12 that converts the signal 33 and the output signal from the A / D converter 12, and is output to the first offset canceller 21. The reproduction signal amplitude adjusting unit 22 is controlled from the output signals from the offset control unit 30 and the A / D converter 12. An amplitude control unit 31 that generates gain control information for output to the reproduction signal amplitude adjustment unit 22 and a second offset canceller that removes an offset component (DC component) from the output signal from the A / D converter 12 24 and a data demodulator 25 that performs data demodulation to generate a digital binarized signal 49 and a reproduction clock 32 indicating a clock component included in the RF signal 14 from the output signal from the second offset canceller 24. And have.

  Further, the OPC information detection unit 20 more specifically, the digital RF signal 33 from the A / D converter 12, the offset control information output from the offset control unit 30, and the gain output from the amplitude control unit 31. Using the control information, the digital RF signal 33 from the A / D converter 12 is subjected to reverse correction using the gain control information and the offset control information, and then the peak value, the bottom value, and the average value are extracted and extracted. The modulation degree information 27 and the asymmetry information 28 are generated using the peak value, the bottom value, and the average value. Therefore, the OPC information detection unit 20 uses, as a characteristic component, the gain control information output from the amplitude control unit 31 when the gate signal 17 is not output from the gate signal generation unit 16 (negated). The gate signal 17 is not output from the amplitude reverse correction unit 50 that restores amplitude information by performing reverse correction on the digital RF signal 33 from the A / D converter originally (the negated signal) ), A DC reverse correction unit 51 that restores a DC component by performing reverse correction on the digital RF signal 33 from the A / D converter 12 based on the offset control information output from the offset control unit 30. Have.

  Note that the recording power adjustment unit 69 operates in synchronization with the reproduction clock 32 output from the data demodulation unit 25, and the digital binarized signal 49 output from the data demodulation unit 25 and the OPC information detection unit 20. Based on the output modulation degree information 27 and asymmetry information 28, the optimum laser recording power is adjusted.

  The data recording / reproducing apparatus further includes an optical disk controller 18 that generates a measurement timing signal 19 that is timing information for controlling the gate signal generator 16 based on the digital binarized signal 49. Then, the gate signal generation unit 16 generates a gate signal 17 that can specify an arbitrary time interval from the measurement timing signal 19 output from the optical disk controller 18, and the DC signal is transmitted to the signal selection unit 15 by the gate signal 17. And the operation of the first offset canceller 21, the reproduction signal amplitude adjusting unit 22, the second offset canceller 24, and the data demodulating unit 25 are held. As a result, the OPC information detection unit 20 is caused to detect the DC correction information and the gain difference information to generate the modulation degree information 27. At that time, it is better to turn off (bypass) the function of the equalizer 23.

  The modulation degree detection apparatus according to the present invention is an apparatus constituted by some components of the data recording / reproducing apparatus. That is, the modulation degree detection apparatus according to the present invention includes a four-divided photodetector 5 that detects an optical signal divided into four from an optical recording medium 1 by a track direction axis and a radial axis perpendicular to the track direction axis. An apparatus that generates modulation degree information 27 and asymmetry information 28 based on a signal from the optical pickup 3 that includes the addition signal detection unit 9 and the amplitude adjustment unit 10 among the components included in the data recording / reproducing apparatus. An adder 13, a gate signal generation unit 16, a signal selection unit 15, a reproduction signal processing unit 82, and an OPC information detection unit 20.

  Such a data recording / reproducing apparatus and modulation degree detecting apparatus provide modulation degree information 27 and asymmetry information 28 necessary for OPC for optimally recording digital data on the optical recording medium 1, RF signal 14 and 4ch addition signal 11. Therefore, it is possible to reduce the circuit area and power consumption by generating the data with high accuracy and the minimum scale. Hereinafter, the configurations of the data recording / reproducing apparatus and the modulation degree detecting apparatus will be described in detail.

  When recording digital data on the optical recording medium 1, in order to record data with high accuracy with respect to the recording sensitivity, temperature, and laser wavelength variation of the disk film of the optical recording medium 1, It is necessary to optimally adjust the laser recording power. This adjustment is OPC. For example, a test writing is performed by applying power to (or applying to) a PCA (Power Calibration Area) existing in the inner periphery of the optical recording medium 1, and the recorded signal is read out, In order to determine the optimum power in accordance with the modulation degree information 27 which is an index indicating the difference in the reflectance of the non-pit portion and the asymmetry information 28 which is an index indicating the asymmetry between the pit portion and the non-pit portion, the recorded data is modulated. Accurately grasping the degree information 27 and the asymmetry information 28 is necessary for improving the quality of the recorded data.

  Hereinafter, each component included in the data recording / reproducing apparatus and the modulation degree detecting apparatus will be described in detail.

  In FIG. 1, an optical recording medium (optical disk medium) 1 is an information recording medium having a thin film of, for example, a phase change recording material for recording digital data, and tracks are formed in a spiral shape or a concentric shape at predetermined intervals. Has been. The rewritable DVD-RW disc and BD-RE disc, which are one of the optical recording media 1, and the DVD-R disc and BD-R disc that can be written only once have a PCA area, and at the time of OPC Used to optimize laser recording power.

  The optical recording medium rotation control unit 2 is a circuit or mechanism for rotating the optical recording medium 1 at a predetermined linear velocity. As an example, the optical recording medium rotation control unit 2 may be configured by a spindle motor, a stepping motor, and the like.

  When reading out digital data from the optical recording medium 1, the optical pickup 3 converts the reflected light from the optical spot into an electric signal and an actuator equipped with a laser generating unit 4 that scans the track with the light spot focused. A four-divided photodetector 5 for detecting a tracking error signal and a push-pull signal and a two-divided photodetector 6 for detecting a focus error signal are provided. A detailed configuration of the optical pickup 3 is shown in FIG. As shown in FIG. 2, the quadrant photodetector 5 is divided into four regions 5a to 5d by a track direction axis and a radial axis perpendicular to the track direction axis.

  As shown in FIG. 1, the adder 7 includes a current-voltage conversion for converting the detection current output from the two regions 5a and 5d out of the four regions 5a to 5d of the four-divided photodetector into a voltage, and their track directions. Are added to the components of the regions 5a and 5d which are parallel to each other. The adder 8 converts the detection current output from the two areas 5b to 5c out of the four areas 5a to 5d of the four-divided photodetector into a voltage and the areas 5b and 5c parallel to the track direction. Is added.

  The output signal from the adder 7 and the output signal from the adder 8 are input to the addition signal detection unit 9 and subjected to voltage addition. An output signal from the addition signal detection unit 9 is input to an amplitude adjustment unit 10 configured by a VGA (Voltage Gain Amplitude; hereinafter referred to as “VGA”) or the like whose gain can be arbitrarily changed. It is generated and output as a 4ch addition signal 11 adjusted to an amplitude suitable for the dynamic range of the input signal of the D converter 12.

  On the other hand, the adder 13 corresponds to an RF signal generation unit that generates an RF signal. Here, the adder 13 is a current that converts the detection current output from the two regions 6a and 6b of the two-divided photodetector 6 shown in FIG. 2 into a voltage. -Voltage conversion is performed, and the voltage after the conversion is added to the output signal from the addition signal detection unit 9 to generate the RF signal 14. Note that such a method of generating the RF signal 14 is an example, and the RF signal 14 may be generated using only the output signal from the addition signal detection unit 9.

  After the RF signal 14 and the 4ch addition signal 11 are input to the signal selection unit 15, either one is selected by the signal selection unit 15 by the gate signal 17 generated by the gate signal generation unit 16 and output. Here, the relationship between the gate signal 17 and the output signal from the signal selector 15 is shown in FIG. 3 as an example. FIG. 3 shows operation timings of the data recording / reproducing apparatus and the modulation degree detecting apparatus related to the gate signal. As shown in FIG. 3, when the measurement timing signal 19 that is an output signal from the optical disk controller 18 composed of a CPU and software (program) is asserted, the signal selection unit 15 asserts the gate signal 17 (here, After selecting an arbitrary section, for example, several frame sections defined in the data format of the optical recording medium 1 such as a DVD medium, negation is performed. In a period in which the gate signal 17 is High (asserted), the 4ch addition signal 11 is selected as an output signal from the signal selection unit 15. On the other hand, the RF signal 14 is selected as the output signal from the signal selection unit 15 in the section where the gate signal 17 is Low (negate).

  At that time, various controls (operations) in the first offset canceller 21, the reproduction signal amplitude adjusting unit 22, the second offset canceller 24, and the data demodulating unit 25 are held in a section where the gate signal 17 becomes High. The Also, the equalizer 23 is turned off or bypassed. Thereby, DC correction information and gain difference information are detected by the 4ch addition gain difference & DC information conversion unit 26 which is one of the constituent elements of the OPC information detection unit 20, and the modulation degree detection unit 67 provides accurate modulation degree information 27. It is possible to convert to Such DC correction information and gain difference information are used as correction values for correcting the modulation degree information 27 and the asymmetry information 28 when the measurement timing signal 19 is negated, and then the 4ch addition gain difference & DC information conversion unit 26 The internal information is refreshed, and the modulation degree information 27 and the asymmetry information 28 may be calculated using the same correction value until the next correction.

  Note that the gate signal generation unit 16 may be fixed to High when data reproduction is not performed based on the digital binarized signal 49 output from the data demodulation unit 25 as the gate signal 17 to be generated. Thereby, the modulation degree information 27 and the asymmetry information 28 are detected in a period in which data reproduction is not performed.

  The optical disk controller 18 determines that the measurement timing signal 19 to be generated is beyond the correction limit based on the digital binarized signal 49 output from the data demodulator 25, that is, the reproduction is impossible. In some cases, the timing of assertion may be extended or stopped. As a result, such a determination is made by the CPU and software (program) provided in the optical disk controller 18, so that even when the optical recording medium 1 is originally contaminated with fingerprints or fingerprints, reproduction is difficult. Thus, data reproduction and generation of modulation degree information can be performed simultaneously.

  With the above configuration, according to the data recording / reproducing apparatus and the modulation degree detecting apparatus in the present embodiment, since there is no dedicated analog circuit for detecting OPC information as in the prior art, the circuit scale and power consumption can be reduced. It becomes possible.

  Further, according to the data recording / reproducing apparatus and the modulation degree detecting apparatus in the present embodiment, the offset control unit 30, the DC reverse correction unit 51 utilizing the offset control unit 31, the amplitude control unit 31, and the amplitude reverse correction unit 50 utilizing the same. Since the OPC information can be detected while the first offset canceller 21 and the reproduction signal amplitude adjusting unit 22 are operated, the modulation degree information and the asymmetry information can be detected simultaneously with the data reproduction. Since it is not necessary to individually acquire signal quality, modulation degree information and asymmetry information divided into two (two different time intervals), the learning time required for adjusting the laser recording power during OPC, It is possible to shorten the startup time of the apparatus.

  Next, the detection principle of the modulation degree information 27 and the asymmetry information 28 by the OPC information detection unit 20 is shown in FIG. When the 4ch addition signal 11 is selected by the signal selection unit 15 based on the gate signal 17, the OPC information detection unit 20 detects the modulation degree information 27 and the asymmetry information 28 as follows. That is, the modulation degree information 27 is input with the digital RF signal 33 that is an output signal from the A / D converter 12, and the DC level of the digital RF signal 33 when the laser is off ("reference level when the laser is off" in FIG. 4). From the peak value and the bottom value of the 4ch addition signal 11 with reference to ## EQU1 ## Further, the asymmetry information 28 is obtained by the equation 2 shown in FIG. 4 from the peak value, the bottom value, and the average value in FIG.

  Further, the OPC information detection unit 20 corrects the peak value, the bottom value, and the average value by using the RF signal 14 that is selected when the gate signal 17 is Low based on the information obtained here. Further, it becomes possible to detect the modulation degree information 27 and the asymmetry information 28 with higher accuracy. Detailed components of the OPC information detection unit 20 will be described later.

  On the other hand, when the RF signal 14 is selected by the signal selection unit 15 based on the gate signal 17, the reproduction signal processing unit 82 performs data reproduction according to the following flow. First, an output signal from the signal selection unit 15 is input to the first offset canceller 21 and adjusted to an offset level appropriate for the dynamic range of the A / D converter 12.

  The first offset canceller 21 has a D / A converter and the like, and may operate on the following principle. First, the offset control unit 30 detects the offset level from the digital RF signal 33 that is an output signal from the A / D converter 12, and sets a digital value that makes the difference from the target level to be originally controlled zero. The offset control information is detected, and the offset control information is output to the first offset canceller 21. The first offset canceller 21 converts the offset control information into an analog quantity with a built-in D / A converter or the like, and the signal selection unit 15 makes an appropriate offset with respect to the dynamic range of the A / D converter 12. Adjust the offset of the input signal. Note that when the 4ch addition signal 11 is selected by the signal selection unit 15 because the gate signal 17 is High, it is desirable that the first offset canceller 21 holds the operation. In this case, the first offset canceller 21 holds the offset control information input before the gate signal 17 is asserted (becomes High), and after the gate signal 17 is negated (at Low), Control may be resumed using the offset control information that has been held. As a result, stable data reproduction that is not affected by the difference in the time interval during which the 4ch addition signal 11 was selected can be performed.

  The output signal from the first offset canceller 21 is input to the reproduction signal amplitude adjusting unit 22 and adjusted to an amplitude appropriate for the dynamic range of the A / D converter 12.

  Note that the reproduction signal amplitude adjusting unit 22 is a circuit configured by a VGA or the like that can change the gain, and includes a D / A converter or the like, and may operate according to the following principle. First, the amplitude control unit 31 detects the amplitude information from the digital RF signal 33 that is an output signal from the A / D converter 12, and has a digital value that makes the difference from the amplitude target to be controlled zero. The gain control information is detected, and the gain control information is output to the reproduction signal amplitude adjusting unit 22. The reproduction signal amplitude adjusting unit 22 converts the gain control information into an analog amount by using a built-in D / A converter or the like, and adjusts the amplitude to an appropriate amplitude with respect to the dynamic range of the A / D converter 12 by using a VGA or the like. An AGC (Auto Gain Control) function for adjusting the amplitude of the signal input from one offset canceller 21 is exhibited. Note that when the 4ch addition signal 11 is selected by the signal selection unit 15 because the gate signal 17 is High, it is desirable that the reproduction signal amplitude adjustment unit 22 hold the operation. In this case, the reproduction signal amplitude adjusting unit 22 holds the gain control information input before the gate signal 17 is asserted (becomes High), and after the gate signal 17 is negated (at Low), Control may be resumed using the held gain control information. As a result, stable data reproduction that is not affected by the difference in the time interval during which the 4ch addition signal 11 was selected can be performed.

  The output signal from the reproduction signal amplitude adjusting unit 22 is input to the equalizer 23, where frequency characteristics are corrected and noise is removed.

  The equalizer 23 may operate on the following principle. Here, in the RF signal 14, the higher the recording density in the linear direction according to the pattern of the adjacent recording code, the more the amplitude attenuation of the reproduction waveform becomes more significant in the high frequency component, and the jitter component of the RF signal 14 deteriorates. Connected. Therefore, the equalizer 23 corrects the high frequency (high frequency component) to be emphasized and removes noise components existing in a band other than the demodulated signal to improve the jitter. Here, the equalizer 23 is configured by a filter that can arbitrarily set the boost amount and the cutoff frequency. This filter may be, for example, a high-order equiripple filter having frequency characteristics as indicated by a solid line in FIG. In this figure, the characteristic indicated by the dotted line is a characteristic when high-frequency boost is not performed. When the 4ch addition signal 11 is selected by the signal selection unit 15 because the gate signal 17 is High, the equalizer 23 desirably bypasses the input signal and outputs it as it is.

  An output signal from the equalizer 23 is input to the A / D converter 12. The A / D converter 12 is a circuit that operates in synchronization with the timing of the reproduction clock 32 generated from the data demodulator 25 and converts an input analog signal into a digital RF signal 33 that is a multi-bit digital signal. .

  The digital RF signal 33 is input to the second offset canceller 24, whereby the offset component included in the digital RF signal 33 is reduced.

  The second offset canceller 24 may include, for example, a circuit configuration (an offset level detection unit 34, an offset level smoothing unit 35, and a subtraction unit 36) as shown in FIG. Hereinafter, the operation of the second offset canceller 24 having the circuit configuration shown in FIG. 6 will be described. However, this circuit and principle are examples, and the present invention is not limited to this circuit and principle.

  In FIG. 6, the offset level detector 34 detects offset level information from the input digital RF signal 33. The offset level smoothing unit 35 smoothes the offset level information detected by the offset level detection unit 34. Next, the subtractor 36 subtracts the smoothed offset level information from the digital RF signal 33 to reduce the offset component included in the digital RF signal 33. The offset level detection unit 34 outputs the phase information when it is determined as the zero cross position in the digital RF signal 33 as center level fluctuation information. On the other hand, “+ A” is added when the polarity of the digital RF signal 33 is positive with respect to the zero level, and “−A” is added when the polarity is negative (A is an arbitrary positive number). Accumulate information. At this time, since the accumulated signal becomes information indicating the balance of the sign polarity of the output signal from the second offset canceller 24, the offset information with the sign center level can be extracted based on the information. Next, the offset level information is generated by adding the center level variation information and the information indicating the balance of the sign polarity at an arbitrary ratio. As a result, the offset component present in the digital RF signal 33 can be reduced, so that phase synchronization control (PLL (Phase Locked Loop) control hereinafter) or data demodulation processing, which will be described later, is performed. Improve accuracy and performance. When the 4ch addition signal 11 is selected by the signal selection unit 15 because the gate signal 17 is High, it is desirable that the second offset canceller 24 holds the operation. In this case, the second offset canceller 24 holds the information of the offset level smoothing unit 35 before the gate signal 17 is asserted (becomes High), and after the gate signal 17 is negated (at Low). The control may be resumed using the information stored in the offset level smoothing unit 35. As a result, stable data reproduction can be performed without being affected by the difference in the signal in the section in which the 4ch addition signal 11 is selected.

  As described above, the digital RF signal 33 is a signal obtained by sampling by the A / D converter 12 with the reproduction clock 32 synchronized with the phase of the clock component of the channel bit frequency included in the RF signal 14 as a reference. At that time, the data demodulator 25 which is a circuit for generating the recovered clock 32 may include a phase synchronization controller 37 having the circuit configuration shown in FIG. The phase synchronization control unit 37 includes a zero-cross information detection unit 38, a linear interpolation unit 41, a polarity inversion unit 42, a switching unit 43, a mask processing unit 44, phase error information 45, a phase synchronization loop filter 46, a digital / analog converter 47, and A VCO 48 is provided. Here, the reproduction clock 32 is a signal input to a D flip-flop or the like in a circuit for processing a digital signal after the A / D converter 12. Since the reproduction clock 32 becomes an operation clock of the digital circuit after the A / D converter 12, even when the reproduction speed is different, appropriate signal processing following the channel frequency component included in the RF signal 14 can be realized. At the same time as realizing the reproduction performance independent of the reproduction speed, it becomes possible to stabilize and reduce the scale and power of the digital circuit. Depending on the operation band of the digital circuit provided in the data recording / reproducing apparatus and the modulation degree detecting apparatus, the reproduction clock 32 can be operated by dividing it by N (N is an arbitrary integer equal to or greater than 2), so that more power and circuit can be obtained. Can be streamlined.

  The operation and principle of the data demodulator 25 having the phase synchronization controller 37 will be described below with reference to FIGS. FIG. 8 is a diagram for explaining the operation of the phase synchronization control unit 37. However, the detailed circuit configuration of the phase synchronization control unit 37 shown in FIG. 7 is an example, and is not limited to this circuit configuration.

  As shown in FIG. 7, the zero-cross information detection unit 38, for example, outputs a zero-cross position detection signal 39 from the output signal from the second offset canceller 24 as shown by a white circle in FIG. 8 or the digital RF signal 33, A polarity selection signal 40 indicating whether the position is a rising edge or a falling edge is generated. On the other hand, the output signal from the second offset canceller 24 is converted into an intermediate signal as indicated by a black square in FIG. 8 by linearly interpolating signals corresponding to adjacent white circles input to the linear interpolation unit 41. Converted. This signal becomes the reference signal for the phase error signal. The polarity inversion unit 42 has a function of inverting the polarity of the output signal from the linear interpolation unit 41. When the polarity selection signal 40 indicates “negative”, the switching unit 43 selects a signal output from the polarity inversion unit 42 as indicated by a white square in FIG. When “positive” is indicated, an output signal from the linear interpolation unit 41 as shown by a black square in FIG. 8 is selected. Next, the mask processing unit 44 outputs the output signal from the switching unit 43 as the phase error information 45 only when it is determined based on the zero cross position detection signal 39 that the zero cross position, that is, the polarity is reversed. At that time, the mask processing unit 44 may hold the phase error information 45 not only at the moment of polarity switching but also until the next zero cross position. The phase error information 45 obtained in this way is indicated by “P1”, “P2”, “P3”, “P4” in FIG. Here, for the phase error information “P2” and “P4” corresponding to the falling edge indicated by the white square, the switching unit 43 selects the output signal from the polarity inverting unit 42. The digital phase control signal output from the phase locked loop filter 46 is converted into an analog control signal after being filtered by the phase locked loop filter 46 using the phase error information 45 thus detected. To the digital / analog converter 47. Next, the VCO 48 oscillates a clock with reference to the output voltage of the digital / analog converter 47. The output clock of the VCO 48 is converted into a recovered clock 32 after frequency division or the like. Here, the phase-locked loop filter 46 may adjust the gains of the proportional component and the integral component, mix them, and perform the integration process. That is, the feedback control is performed so that the A / D converter 12 → the second offset canceller 24 → the phase synchronization control unit 37 → the VCO 48 → the A / D converter 12 is the main control loop, and the phase error information 45 is zero. As a result, the digital RF signal 33 synchronized with the phase of the clock component of the channel bit frequency of the RF signal 14 can be generated. Further, when digital data is not recorded on the optical recording medium 1, the oscillation frequency of the reproduction clock 32 may be fixed.

  When the 4ch addition signal 11 is selected by the signal selection unit 15 because the gate signal 17 is High, it is desirable that the phase synchronization control unit 37 hold the operation. In this case, the phase synchronization control unit 37 holds the control information of the phase synchronization loop filter 46 before the gate signal 17 is asserted (becomes High), and after the gate signal 17 is negated (at the time of Low), Control may be resumed using the held control information of the phase-locked loop filter 46. As a result, stable data reproduction can be performed without being affected by the difference in the signal in the section in which the 4ch addition signal 11 is selected.

  In order to demodulate the digital data recorded on the optical recording medium 1, the data demodulating unit 25 determines whether the output signal from the second offset canceller 24 is on the upper side with reference to the center level as shown in FIG. On the lower side, “1” is determined to be “0”. The digital binarized signal 49 demodulated by the data demodulator 25 is input to the optical disc controller 18 and then subjected to error correction processing or the like in the optical disc controller 18 to be converted into more error-free digital data.

  As a method of generating the digital binarized signal 49, not only a method of discriminating “1” and “0” above or below the level described above but also PRML (Partial Response Maximum Likelihood) is used. It is also possible to use a discrimination method that is less prone to error using a simple probability calculation. Note that when the 4ch addition signal 11 is selected by the signal selection unit 15 because the gate signal 17 is High, the data demodulation unit 25 desirably holds the operation. In this case, the data demodulator 25 holds each control information before the gate signal 17 is asserted (becomes High), and after the gate signal 17 is negated (at the time of Low), each of the held control information is stored. Control may be resumed using the information. As a result, stable data reproduction can be performed without being affected by the difference in the signal in the section in which the 4ch addition signal 11 is selected.

  As described above, the measurement timing signal 19 generated by the optical disk controller 18 exceeds the correction limit based on the digital binarized signal 49 output from the data demodulator 25, that is, cannot be reproduced. If it is determined, the timing for asserting may be extended or stopped. By making the above determination with the CPU and software (program) provided in the optical disk controller 18, data playback can be performed even when the optical recording medium 1 is originally contaminated with dirt or fingerprints and difficult to reproduce. It is possible to simultaneously generate the modulation degree information.

  Next, the function of the OPC information detection unit 20 and the detection principle of the modulation degree information 27 and the asymmetry information 28 will be described. The OPC information detection unit 20 is a digital signal processing circuit. As illustrated in FIG. 1, the amplitude reverse correction unit 50, the DC reverse correction unit 51, the first LPF 52, the section peak detection unit 53, and the section bottom detection unit 54. A second LPF 55, a peak value averaging unit 56, a bottom value averaging unit 57, an average value averaging unit 58, a 4ch addition gain difference & DC information conversion unit 26, a modulation degree detection unit 67, and an asymmetry detection unit 68.

  A digital RF signal 33 that is an output of the A / D converter 12 is input to the OPC information detection unit 20. The target when the modulation degree information 27 and the asymmetry information 28 are detected by the OPC information detection unit 20 is a section in which the 4ch addition signal 11 having a DC component is selected by the signal selection unit 15 based on the gate signal 17. Therefore, for example, in the section where the RF signal 14 in which the gate signal 17 becomes Low is selected, it is possible to stabilize the detection accuracy of the modulation degree information 27 and the asymmetry information 28 by performing the hold process.

  The input digital RF signal 33 is first input to the amplitude reverse correction unit 50. The amplitude reverse correcting unit 50 outputs the input signal as it is when the reproduction signal amplitude adjusting unit 22 is held by the gate signal 17. On the other hand, when the reproduction signal amplitude adjustment unit 22 is not held by the gate signal 17, the amplitude reverse correction unit 50 sets the amplitude level of the digital RF signal 33 based on the gain control information output from the amplitude control unit 31. The amplitude level corresponding to the output signal from the first offset canceller 21 is converted. By such a function of the amplitude reverse correction unit 50, the amplitude information of the digital RF signal 33 is reproduced while performing the amplitude adjustment by the reproduction signal amplitude adjustment unit 22, so that the dynamic range of the A / D converter 12 is effectively utilized. Therefore, the detection accuracy of the modulation degree information 27 and the asymmetry information 28 can be improved.

  An output signal from the amplitude reverse correction unit 50 is input to the DC reverse correction unit 51. The DC reverse correction unit 51 outputs the input signal as it is when the first offset canceller 21 is held by the gate signal 17. On the other hand, when the first offset canceller 21 is not held by the gate signal 17, the DC reverse correction unit 51 outputs from the amplitude reverse correction unit 50 based on the offset control information that is the output of the offset control unit 30. The offset level of the signal is converted into an offset level corresponding to the input signal of the first offset canceller 21. With such a function of the DC reverse correction unit 51, the offset component of the digital RF signal 33 is reproduced while performing offset cancellation by the first offset canceller 21, so that the degree of freedom of the amplitude adjustment unit 10 is increased, and A / Since the dynamic range of the D converter 12 can be used effectively, the detection accuracy of the modulation degree information 27 and the asymmetry information 28 can be improved.

  An output signal from the DC reverse correction unit 51 is input to a first LPF (Low Pass Filter) 52. The first LPF 52 removes high-frequency noise that hinders the detection accuracy of the modulation degree information 27 and the asymmetry information 28 from the input signal.

  An output signal from the first LPF 52 is input to the section peak detection unit 53, the section bottom detection unit 54, and the second LPF 55.

  Here, for example, the section peak detection unit 53 detects the peak envelope by holding the maximum value of the input signal within an arbitrary time. Similarly, the section bottom detector 54 detects the bottom envelope by holding the minimum value of the input signal within an arbitrary time as an example. The second LPF 55 may detect an average level of all data of the input signal, and may extract an average level by functioning as an LPF having a cutoff frequency lower than that of the first LPF 52.

  An output signal from the section peak detection unit 53 is input to a peak value averaging unit 56 configured by an LPF or the like, and then a peak value as shown in FIG. 4 is detected.

  An output signal from the section bottom detection unit 54 may be input to a bottom value averaging unit 57 configured by an LPF or the like, and then a bottom value as illustrated in FIG. 4 may be detected.

  The output signal from the second LPF 55 is input to an average value averaging unit 58 constituted by an LPF or the like, and then an average value as shown in FIG. 4 is detected.

  The first LPF 52, the second LPF 55, the peak value averaging unit 56, the bottom value averaging unit 57, and the average value averaging unit 58 are configured by a cyclic filter as shown in FIG. May be configured by a combination of two primary digital low-pass filters (two primary digital low-pass filters 59a and 59b). FIG. 9 shows a configuration of a secondary digital low-pass filter, which is an application circuit of a cyclic filter, as an example of a combination of two primary digital low-pass filters. Hereinafter, the operation of the second-order digital low-pass filter will be described, but this circuit is an example and is not limited to this circuit.

  This second-order digital low-pass filter is composed of two first-order digital low-pass filters composed of an adder 60, a subtractor 61, a clip processor 62, an initialization unit 63, a register 64, and a cutoff frequency setting unit 65. It comprises filters 59a and 59b and an output selection unit 66. As shown in FIG. 9, the filter input signal is first input to the adder 60 of the first-stage primary digital low-pass filter 59a. The adder 60 has a function of adding the filter input signal and the output signal from the subtractor 61. The output signal from the adding unit 60 is input to the clip processing unit 62, and when the upper limit value exceeds the maximum bit width, the output signal is clipped to the closest upper limit value or lower limit value. An output signal from the clip processing unit 62 is input to the initialization unit 63. The initialization unit 63 performs initialization when starting the primary digital low-pass filter 59a and switching the drive clock. An output signal from the initialization unit 63 is input to a register 64 having a function of holding the input digital data at the timing of the drive clock. The output signal of the register 64 is input to the cut-off frequency setting unit 65 for setting the cut-off frequency of the primary digital low-pass filter 59a and the subtraction unit 61. Here, the cutoff frequency setting unit 65 is a circuit that easily adjusts the gain, such as a bit shift circuit. The subtracting unit 61 subtracts the output signal of the primary digital low-pass filter 59a, which is the output signal of the cutoff frequency setting unit 65, from the output signal of the register 64.

  Subsequently, the output signal from the primary digital low-pass filter 59a is input to another primary digital low-pass filter 59b in the subsequent stage. The downstream primary digital low-pass filter 59b has basically the same configuration as that of the upstream primary digital low-pass filter 59a described above. The output signal from the primary digital low-pass filter 59a in the preceding stage and the output signal from the primary digital low-pass filter 59b in the subsequent stage are input to the output selection unit 66, and one of the input signals is selected. Is output. Thereby, the performance of either the primary filter or the secondary filter can be selected for the secondary digital low-pass filter shown in FIG.

  The high-order noise component of the filter input signal can be removed by the secondary digital low-pass filter realized by the series connection of the series of cyclic digital filters described above. It is also possible to perform an averaging process. By applying such a simple cyclic digital low-pass filter, it is possible to reduce the size of the digital circuit, thereby reducing the cost.

  The peak value that is the output signal from the peak value averaging unit 56 and the bottom value that is the output signal from the bottom value averaging unit 57 are input to the 4ch addition gain difference & DC information conversion unit 26, and then the amplitude is adjusted. Based on the gain information applied by the unit 10 and the reference level when the laser is turned off, the modulation degree conversion information is calculated, and the calculated modulation degree conversion information is transmitted to the modulation degree detection unit 67. Here, the information at the time of turning off the laser is a value that holds information on the average value of the detected peak value and bottom value after turning off the laser by the laser generator 4. The peak value and the bottom value and the output information from the 4ch addition gain difference & DC information conversion unit 26 are input to the modulation degree detection unit 67, and then the modulation degree information 27 is obtained by Expression 1 shown in FIG. . On the other hand, the peak value and the bottom value, and the average value that is an output signal from the average value averaging unit 58 are input to the asymmetry detection unit 68, and then the asymmetry information 28 is obtained by Expression 2 shown in FIG. It is done.

  The optical disk controller 18 is a circuit composed of a CPU, software (program), and the like, and is suitable for recording on the optical recording medium 1 through the recording power adjustment unit 69 based on the modulation degree information 27 and the asymmetry information 28. Determine power. The recording power adjustment unit 69 records data on the optical recording medium 1 through the laser generation unit 4 based on the recording power determined by the optical disk controller 18.

  With the above-described series of functions, the data recording / reproducing apparatus and modulation degree detecting apparatus according to the present embodiment can perform digital binary processing even without a dedicated analog signal processing circuit for detecting OPC information as in the prior art. Since it is possible to accurately estimate the data demodulation-related functions necessary for generating the digitized signal and the modulation degree information and asymmetry information necessary for OPC, it is possible to reduce the circuit scale and power.

  Further, according to the data recording / reproducing apparatus and the modulation degree detecting apparatus in the present embodiment, the offset control unit 30, the DC reverse correction unit 51 utilizing the offset control unit 31, the amplitude control unit 31, and the amplitude reverse correction unit 50 utilizing the same. Since the OPC information can be detected while the first offset canceller 21 and the reproduction signal amplitude adjusting unit 22 are operated, the modulation degree information and the asymmetry information can be detected simultaneously with the data reproduction. Since there is no need to acquire information divided into (two different time intervals), it is possible to shorten the learning time during OPC and the startup time of the apparatus.

  Furthermore, according to the data recording / reproducing apparatus and modulation degree detecting apparatus in the present embodiment, it is possible to effectively use the dynamic range and bit width of the A / D converter by applying offset control and gain control. Since there is an advantage that it can be constructed with the minimum dynamic range and bit width necessary for data demodulation, the circuit scale and power of the A / D converter can be suppressed. That is, the problem that the circuit scale and power of the A / D converter are sacrificed due to the combined use of data reproduction and preprocessing for detecting OPC information in the reproduction signal processing unit is avoided.

  In particular, according to the data recording / reproducing apparatus and the modulation degree detecting apparatus of the present embodiment, when implemented using a semiconductor integrated circuit, the data recording / reproducing apparatus and the modulation degree detecting apparatus with a small circuit scale and low power consumption are provided. It becomes possible to provide.

  As described above, the data recording / reproducing apparatus and the modulation degree detecting apparatus according to the present invention have been described based on the embodiments. However, the present invention is not limited to such embodiments. The present invention includes forms obtained by making various modifications conceived by those skilled in the art to the embodiments and combinations obtained by arbitrarily combining the constituent elements of the embodiments without departing from the spirit of the present invention. It is.

  For example, in the present embodiment, the gate signal 17 is output with positive logic (High when asserted), but may be output with negative logic (Low when asserted).

  Further, in the present embodiment, when the gate signal 17 is asserted, the operation of some components of the reproduction signal processing unit 82 is held. However, in the data recording / reproducing apparatus and the modulation degree detection apparatus according to the present invention, Such a hold function is not necessarily required. Since the OPC information detection unit 20 in the present embodiment includes the amplitude reverse correction unit 50 and the DC reverse correction unit 51, the A / D converter 12 is operated because the first offset canceller 21 and the reproduction signal amplitude adjustment unit 22 are operated. Even when the DC component and the amplitude information are not included in the digital RF signal 33 output from the signal, the amplitude information and the DC component are restored in the amplitude reverse correction unit 50 and the DC reverse correction unit 51. is there.

  The present invention relates to a data recording / reproducing apparatus and a modulation degree detecting apparatus thereof, in particular, pre-processing for detecting OPC information which is modulation degree information and asymmetry information necessary for recording data and data reproduction in common. By using the reproduction signal processing unit, a dedicated analog circuit for detecting OPC information is not required and power can be saved. Therefore, a recording / reproduction DVD super multi-drive mounted on a notebook PC, Blu-ray Useful as a recorder.

1 Optical recording media (optical disc media)
2 Optical recording medium rotation control unit 3 Optical pickup 4 Laser generating unit 5 4 divided photo detectors 5a to 5d 4 divided photo detector divided regions 6 2 divided photo detectors 6a and 6b 2 divided photo detector divided regions 7 and 8 Adder 9 Addition signal detecting unit 10 Amplitude adjustment section 11 4ch addition signal 12 A / D converter 13 Adder (RF signal generation section)
14 RF signal 15 Signal selection unit 16 Gate signal generation unit 17 Gate signal 18 Optical disk controller 19 Measurement timing signal 20, 91 OPC information detection unit 21 First offset canceller 22 Playback signal amplitude adjustment unit 23 Equalizer 24 Second offset canceller 25 Data demodulation unit 26 4ch addition gain difference & DC information conversion unit 27 Modulation degree information 28 Asymmetry information 30 Offset control unit 31 Amplitude control unit 32 Reproduction clock 33 Digital RF signal 34 Offset level detection unit 35 Offset level smoothing unit 36 Subtraction unit 37 Phase Synchronization control unit 38 Zero cross information detection unit 39 Zero cross position detection signal 40 Polarity selection signal 41 Linear interpolation unit 42 Polarity inversion unit 43 Switching unit 44 Mask processing unit 45 Phase error information 46 Phase locked loop filter 47 Le analog converter 48 VCO
49 Digital Binary Signal 50 Amplitude Reverse Correction Unit 51 DC Reverse Correction Unit 52 First LPF
53 Section peak detection section 54 Section bottom detection section 55 Second LPF
56 Peak value averaging unit 57 Bottom value averaging unit 58 Average value averaging units 59a, 59b Primary digital low-pass filter 60 Adder 61 Subtractor 62 Clip processor 63 Initializer 64 Register 65 Cutoff frequency setting unit ( Gain setting)
66 Output selection unit 67 Modulation degree detection unit 68 Asymmetry detection unit 69 Recording power adjustment unit 70, 71 Amplitude & offset adjustment unit 72 Addition signal detection unit 73, 74 Comparator 75, 76 D / A converter 77 Peak detection unit 78 Bottom detection unit 79 Modulation Degree Detection Unit 80 RF Signal Generation Units 82 and 92 Playback Signal Processing Unit

Claims (6)

An optical pickup including a four-divided photodetector for detecting an optical signal divided into four from an optical recording medium by a track direction axis and a radial axis perpendicular to the track direction axis;
An addition signal detection unit that generates a signal corresponding to the addition result of the optical signal divided into four parts detected by the four-part photodetector;
An amplitude adjustment unit for adjusting the amplitude of the output signal from the addition signal detection unit;
An RF signal generation unit for generating an RF signal as a reproduction signal from the output of the optical pickup;
A gate signal generation unit that generates a gate signal for selecting one of an output signal from the RF signal generation unit and an output signal from the amplitude adjustment unit;
A signal selection unit that selects and outputs either the output signal from the RF signal generation unit and the output signal from the amplitude adjustment unit based on the gate signal generated from the gate signal generation unit;
A reproduction signal processing unit that performs data demodulation by converting an output signal from the signal selection unit into a multi-bit digital signal;
From the digital signal obtained by the reproduction signal processing unit, the modulation degree information which is an index indicating the difference in reflectance between the pit part and the non-pit part in the optical recording medium, and the pit part and the non-pit part in the optical recording medium An optimum recording power control information detector that generates asymmetry information that is an index indicating asymmetry;
Optimal laser recording based on the digital binarized signal after data demodulation output from the reproduction signal processing unit and the modulation degree information and asymmetry information which are output signals from the optimum recording power control information detection unit A recording power adjustment unit for adjusting power,
Data recording / reproducing device. The reproduction signal processor is
A first offset canceller that removes an offset component from the output signal from the signal selection unit;
A reproduction signal amplitude adjusting unit for adjusting the amplitude of the output signal from the first offset canceller;
An equalizer that performs waveform shaping on the output signal from the reproduction signal amplitude adjustment unit;
An A / D converter that converts an analog output signal from the equalizer into a multi-bit digital signal;
An offset control unit that generates offset control information for controlling the first offset canceller from an output signal from the A / D converter and outputs the offset control information to the first offset canceller;
An amplitude control unit that generates gain control information for controlling the reproduction signal amplitude adjustment unit from an output signal from the A / D converter and outputs the gain control information to the reproduction signal amplitude adjustment unit;
A second offset canceller for removing an offset component from the output signal from the A / D converter;
A data demodulator that performs data demodulation to generate a digital binarized signal and a reproduction clock indicating a clock component included in the reproduction signal from an output signal from the second offset canceller;
The optimum recording power control information detection unit outputs the output signal from the A / D converter, the offset control information output from the offset control unit, and the gain control information output from the amplitude control unit. The output signal from the A / D converter is subjected to reverse correction by the gain control information and the offset control information, and then the peak value, the bottom value, and the average value are extracted, and the extracted peak value and the bottom value are extracted. Using the value and the average value, the modulation degree information and the asymmetry information are generated,
The recording power adjustment unit operates in synchronization with the reproduction clock output from the data demodulation unit, and outputs a digital binarized signal output from the data demodulation unit and the optimum recording power control information detection unit. The optimum laser recording power is adjusted based on the modulation degree information and asymmetry information.
The data recording / reproducing apparatus according to claim 1. Furthermore, an optical disk controller that generates timing information for controlling the gate signal generation unit based on the digital binarized signal,
The gate signal generation unit generates a gate signal capable of designating an arbitrary time interval from the timing information output from the optical disc controller, and includes the DC component with respect to the signal selection unit based on the gate signal. The optimum recording power is selected by selecting an output signal from the adjustment unit and holding the operations of the first offset canceller, the reproduction signal amplitude adjustment unit, the second offset canceller, and the data demodulation unit. Causing the control information detection unit to detect DC correction information and gain difference information to generate the modulation degree information;
The data recording / reproducing apparatus according to claim 2. The optimum recording power control information detection unit outputs from the A / D converter based on gain control information output from the amplitude control unit when the gate signal is not output from the gate signal generation unit. An amplitude reverse correction unit that restores amplitude information by performing reverse correction on the signal;
The data recording / reproducing apparatus according to claim 2. The optimum recording power control information detection unit outputs from the A / D converter based on the offset control information output from the offset control unit when the gate signal is not output from the gate signal generation unit. A DC reverse correction unit that restores a DC component by performing reverse correction on the signal;
The data recording / reproducing apparatus according to claim 2. Based on a signal from an optical pickup including a four-divided photodetector for detecting an optical signal divided into four by a track direction axis and a radial axis perpendicular to the track direction axis from the optical recording medium, the optical recording medium Modulation degree detecting device for generating modulation degree information as an index indicating a difference in reflectance between a pit portion and a non-pit portion in an optical recording medium and asymmetry information as an index indicating asymmetry between the pit portion and the non-pit portion in the optical recording medium Because
An addition signal detection unit that generates a signal corresponding to the addition result of the optical signal divided into four parts detected by the four-part photodetector;
An amplitude adjustment unit for adjusting the amplitude of the output signal from the addition signal detection unit;
An RF signal generation unit for generating an RF signal as a reproduction signal from the output of the optical pickup;
A gate signal generation unit that generates a gate signal for selecting one of an output signal from the RF signal generation unit and an output signal from the amplitude adjustment unit;
A signal selection unit that selects and outputs either the output signal from the RF signal generation unit and the output signal from the amplitude adjustment unit based on the gate signal generated from the gate signal generation unit;
A reproduction signal processing unit that performs data demodulation by converting an output signal from the signal selection unit into a multi-bit digital signal;
From the digital signal obtained by the reproduction signal processing unit, the modulation degree information which is an index indicating the difference in reflectance between the pit part and the non-pit part in the optical recording medium, and the pit part and the non-pit part in the optical recording medium An optimum recording power control information detection unit that generates asymmetry information that is an index indicating asymmetry,
Modulation degree detection device.

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