JP4479425B2 - Disc player - Google Patents

Description

  The present invention relates to a disk reproducing apparatus for reproducing the information signal from an optical recording medium on which an information signal is recorded by tracking a spiral groove, for example, and more particularly to reproducing a disk using a radial contrast signal as a track crossing signal. Relates to the device.

  Recently, a magneto-optical disk recording / reproducing apparatus for recording / reproducing information signals on three types of magneto-optical disks having different recording capacities has been developed. The three types of magneto-optical disks are a first generation MD, a high density MD1, and a high density MD3.

  The first generation MD has a diameter of approximately 64 mm, and has a storage capacity that enables recording of a musical sound signal for 74 minutes or more. The high-density MD1 is an MD in which the recording area is increased to, for example, 300 MB by changing the modulation method, the logical structure, and the like to double the user area and the like without changing the first generation MD medium (disk or cartridge). . The high-density MD3 is a magneto-optical disk having a recording capacity increased from that of the high-density MD1, a method in which the track pitch is narrowed to 1.25 μm and the recording mark is detected from the groove by domain wall displacement detection (DWDD). It was adopted. This high-density MD3 employs the DWDD method or the like, thereby setting the total recording capacity to 1 GB.

  As shown in FIG. 17, the physical format of the first generation MD is defined as follows. The track pitch is 1.6 μm and the bit length is 0.59 μm / bit. The laser wavelength λ is λ = 780 nm, and the aperture ratio of the optical head is NA = 0.45. As a recording system, a groove recording system that uses grooves (grooves on the disk board surface) as tracks for recording and reproduction is adopted. The address system employs a system using a wobbled groove in which a single spiral groove is formed on the disk surface and wobbles as address information are formed on both sides of the groove. In this specification, the absolute address recorded by wobbling is also referred to as ADIP (Address in Pregroove). This first generation MD employs an EFM (8-14 conversion) modulation system as a recording data modulation system. As an error correction method, ACIRC (Advanced Cross Interleave Reed-Solomon Code) is used. In addition, a convolution type is adopted for data interleaving. As a result, the data redundancy is 46.3%. The data detection method in the first generation MD is a bit-by-bit method, and CLV (Constant Linear Verocity) is adopted as the disk drive method. The linear velocity of CLV is 1.2 m / s. The standard data rate at the time of recording / reproducing is 133 kB / s, and the recording capacity is 164 MB (140 MB in MD-DATA). The minimum data rewrite unit (cluster) is composed of 36 sectors including 32 main sectors and 4 link sectors.

  The physical specification of the high-density MD1 recording medium is the same as that of the first generation MD. The track pitch is 1.6 μm, the laser wavelength λ is λ = 780 nm, and the aperture ratio of the optical head is NA = 0.45. As a recording method, a groove recording method is adopted. The address system uses ADIP. This high-density MD1 uses an RLL (1-7) PP modulation method (RLL: Run Length Limited, PP: Parity preserve / Prohibit rmtr (repeated minimum transition runlength)) suitable for high-density recording as a modulation method of recording data. Adopted. Further, as an error correction method, an RS-LDC (Reed Solomon-Long Distance Code) method with BIS (Burst Indicator Subcode) having higher correction capability is used.

  The high-density MD3 narrows the track pitch to 1.25 μm and detects the recording mark from the groove by domain wall motion detection (DWDD) as described above. This high-density MD3 uses an RLL (1-7) PP modulation method (RLL: Run Length Limited, PP: Parity preserve / Prohibit rmtr (repeated minimum transition runlength)) suitable for high-density recording as a modulation method of recording data. Adopted. Further, as an error correction method, an RS-LDC (Reed Solomon-Long Distance Code) method with BIS (Burst Indicator Subcode) having higher correction capability is used. Data interleaving is a block-complete type. As a result, the data redundancy becomes 20.50%. As a data detection method, a Viterbi decoding method based on PR (1, -1) ML is used. A cluster which is the minimum data rewrite unit is composed of 16 sectors and 64 kB. A ZCAV system is used as the disk drive system, and the linear velocity is 2.0 m / s. The standard data rate at the time of recording / reproducing is 9.8 MB / s. Therefore, in the high-density MD3, the total recording capacity can be reduced to 1 GB by adopting the DWDD method and this driving method.

  By the way, in a magneto-optical disk recording / reproducing apparatus for recording / reproducing an information signal with respect to the above three types of magneto-optical disks, or a dedicated magneto-optical disk recording / reproducing apparatus for recording / reproducing an information signal for each magneto-optical disk, At the time of access, a radial contrast signal (Radial Contrast) is used as a signal for identifying a track count or an access direction.

  In the first generation MD and the high-density MD1, in a state where tracking is removed at the time of access or the like, the ratio of the AC component to the DC component of the return light amount is set based on the AC component of the total light amount (Pull-In) of the return light. It is used as a radial contrast signal, regarded as a track crossing signal, and used for track count and access direction identification.

  Patent Document 1 listed below describes a technique that uses a radial contrast signal as a track crossing detection signal.

JP-A-62-219334

  By the way, it is difficult to secure sufficient radial contrast in a magneto-optical disk in which the groove pitch is narrowed and the groove is deepened for reproduction by DWDD as in the high-density MD3.

  If the track pitch is narrowed to increase the recording capacity of the disc, the distance of ± first-order diffracted light is increased. In FIG. 18, the diffracted light on PD by the groove from high density MD3 is shown. In the case of high-density MD3, since the distance of ± 1st order diffracted light is separated, the diffracted light on PD is 0th order light and + 1st order light, 0th order light and −1st order, as compared with the first generation MD diffracted light Areas where light overlaps are at the ends of the spot.

  In addition, in a disk adopting DWDD, in order to ensure the characteristics, the groove depth must be deepened, for example, 170 nm. However, as the groove depth approaches λ / 2, The interference intensity of ± 1st order diffracted light falls. As a result, the radial contrast is reduced.

  For the reasons mentioned above, it is difficult to secure a sufficient radial contrast with the high-density MD3.

  The present invention has been made in view of the above circumstances, and can obtain a sufficient radial contrast signal even for an optical disk having a narrow track pitch or a deep groove when a groove is used as a track. It is an object of the present invention to provide an optical disk reproducing apparatus that can perform such a process.

Disk reproducing apparatus according to the present invention, in order to solve the above problems, and reproducing the information signal from the optical recording medium in which information signals to track the groove formed in a spiral shape is recorded, the optical recording medium as a first disk, a disk reproducing apparatus for compatible reproducing and second disc raised a recording capacity by performing a deep groove of the first narrow track pitch and groove to the disk, the Outputs laser light for reading data recorded on the optical recording medium, irradiates the groove with the laser light, and divides the return light from the optical recording medium into a plurality of dividing lines with a light-receiving surface in a tangential direction. an optical head which is received by a plurality of light receiving portions arranged in the radial direction is divided into an electric signal for each of a plurality of light receiving surfaces, electrodeposition of a plurality of light receiving surfaces each of said optical head And a radial contrast signal generating means for generating a radial contrast signal with a signal, when the optical recording medium is the first disk, is the radial contrast signal generating means signals of all the light receiving surface of the light receiving portion When the optical recording medium is the second disk, the radial contrast signal generating means adds the zero-order diffracted light and the ± first-order diffracted light to interfere with each other. A radial contrast signal is generated using a sum signal of two signals at both ends in the radial direction .

  According to the present invention, an apparently large radial contrast signal can be obtained only by changing the electric circuit without changing the dimensions of the optical system due to the structure of the disk.

  According to the present invention, an apparently large radial contrast signal can be obtained only by changing the electric circuit without changing the dimensions of the optical system due to the structure of the disk. In the case of a pickup using the spot size method, since a radial contrast signal can be generated from an intact PD pattern, the compatibility is very good.

  Hereinafter, the best mode for carrying out the present invention will be described. This embodiment is a magneto-optical disk reproducing apparatus which reproduces the first generation MD, the high density MD 1 and the high density MD 3 in a compatible manner. As shown in FIG. 1, the magneto-optical disk recording / reproducing apparatus includes a spindle motor 1 that rotationally drives a loaded magneto-optical disk (any one of the first generation MD, high-density MD1, and high-density MD3) 90. A motor driver that drives the spindle motor 1 based on servo control of a servo circuit 9 to be described later, and a reproducing laser beam is emitted to any one of the magneto-optical disks 90, and recorded information signals are output from the disk 90. An optical head 3 that reads by detecting the polarization component of the return light, and a laser driver 4 that drives a laser light source that emits reproduction laser light in the optical head 3 are provided.

  The magneto-optical disk reproducing apparatus includes an RF amplifier 5 that generates an MO (magneto-magnetic) signal, a radial contrast signal, a tracking error signal, and a focus error signal using an information signal read by the optical head 3, and an RF amplifier 5. A signal reproduction processing circuit 6 that performs signal reproduction processing for reproducing data on the generated MO signal and supplies the reproduced data to the output terminal 7; and an address processing circuit 8 that extracts and decodes address data from the MO signal. With.

  The magneto-optical disk reproducing apparatus servos the objective lens 3a of the optical head 3 in the focus direction and tracking direction of the disk 90 by a biaxial actuator (not shown) based on the tracking error signal and focus error signal generated by the RF amplifier 5. A servo circuit 9 is provided which drives the spindle motor 1 via the motor driver 2 and servo-drives it.

  The magneto-optical disk reproducing apparatus controls the servo circuit 9, the signal reproduction processing circuit 6, and the laser driver 4 based on the address data generated by the address processing circuit 8, and also uses the radial contrast signal generated by the RF amplifier 5. And a controller 10 used as a track crossing signal and used for identifying a track count and an access direction.

  The RF amplifier 5 includes an MO signal generation circuit 5-1 that generates an MO signal using an information signal read by the optical head 3, and a radial contrast signal generation circuit 5-2 that generates a radial contrast signal using the information signal. A tracking error signal generation circuit 5-3 that generates a tracking error signal using the information signal, and a focus error signal generation circuit 5-4 that generates a focus error signal using the information signal.

  The optical head 3 comprises an integrated optical system as shown in FIG. The optical head 3 of the integrated optical system includes a laser diode 31 as a light source, a prism 32 that separates light, an objective lens 3a that collects light, and a photodetector 33 that detects the intensity of light.

  The laser diode 31 is arranged so that the polarization direction is perpendicular to the paper surface, and emits light according to an electric signal input by the laser driver 4. The light emitted from the laser diode 31 is reflected by the slope of the prism 32 and passes through the objective lens 3a. The light that has passed through the objective lens 3 a becomes convergent light and is focused on the recording surface of the magneto-optical disk 90.

  The light irradiated on the surface of the magneto-optical disk 90 is reflected by the surface, converted into convergent light by the objective lens 3a, guided to the prism 32, transmitted through the slope of the prism 32, and condensed on the photodetector 33. . The prism 32 is made of a crystal having anisotropy and has a refractive index that varies depending on the polarization direction. Therefore, incident light can be separated into I and J signals used for the MO signal.

  The photodetector 33 converts incident light into an electrical signal. FIG. 3 is a diagram showing a detector pattern formed on the photodetector 33. As shown in FIG. 3, the photodetector 33 is provided with eleven light receiving portions F, ad, Ix, Iy, Jx, Jy, and each of the light receiving portions F, ad, Ix, Iy. , Jx and Jy are converted into electrical signals. Here, F is a light receiving portion of a photodetector for detecting the laser driving power of the laser light source.

The MO signal generation circuit 5-1 of the RF amplifier 3 includes an arithmetic unit 511 shown in FIG. 4, and electric signals from the light receiving portions Ix, Iy, Jx, Jy of the photodetector 33 (electrical for simplification of explanation). The signals Ix, Iy, Jx, and Jy are calculated as shown in the following equation (1) to calculate the MO signal.
MO (RF) signal = (Ix + Iy) − (Jx + Jy) (1)

The tracking error signal generation circuit 5-3 of the RF amplifier 3 includes an arithmetic unit 513 shown in FIG. 5, and electrical signals from the light receiving portions a, b, c, d of the photodetector 33 (simplification of description). Therefore, electric signals a, b, c, and d) are calculated as shown in the following equation (2) to calculate a tracking error signal.
Tracking error signal = (a + b) − (c + d) (2)

The focus error signal generation circuit 5-4 of the RF amplifier 3 includes an arithmetic unit 514 shown in FIG. 6, and the light receiving portions a, b, c, d of the photodetector 33 and the light receiving portions Ix, Iy, Jx. The electric signal from Jy is calculated as shown in the following equation (3) to calculate a focus error signal.
Focus error signal = ((a + d) − (b + c)) − ((Ix + Jx) − (Iy + Jy)) (3)

Further, the radial contrast signal generation circuit 5-2 of the RF amplifier 3 includes a calculator 512, a calculator 522, and a changeover switch 532 shown in FIG. When the track pitch of the magneto-optical disk 90 is, for example, 1.6 μm and wider than the track pick (1.25 μm) of the high-density MD3, that is, when reproducing the first generation MD or the high-density MD1. The radial contrast signal is calculated as shown in the following equation (4) using the electrical signals from the light receiving portions a, b, c, and d of the photodetector 33.
Radial contrast signal RC = a + b + c + d (4)

Further, the arithmetic unit 522 reproduces the high-density MD3 when the track pitch of the magneto-optical disk 90 is, for example, 1.25 μm and is narrower than the track pick (1.6 μm) of the first generation MD and the high-density MD1. At this time, the radial contrast signal is calculated as shown in the following equation (5) using the electrical signals from the light receiving portions a and d of the photodetector 33.
Radial contrast signal RC = a + d (5)
This equation (5) is a sum signal of electric signals from the light receiving portions a and d at both ends when the four-divided light receiving portions a to d of the photodetector 33 are divided into three as a, b + c, and d. .

  For example, when the disc type discrimination circuit (not shown) in the controller 10 discriminates that the magneto-optical disc (first generation MD, high density MD1) having a wide track pitch is currently being reproduced, The radial contrast signal RC shown in the above equation (4) from the device 512 is selected and output. When the disc type discriminating circuit discriminates that the magneto-optical disc (high density MD3) having a narrow track pick is currently being reproduced, the radial contrast signal shown in the above equation (5) from the computing unit 522 is obtained. Select RC and output.

  Hereinafter, the reason why the sum signal of both ends (a, d) on the photodetectors (a to d) is used as a radial contrast signal in detail when reproducing a magneto-optical disk having a narrow track pick like a high-density MD3 will be described in detail. explain.

  The reflected light from the magneto-optical disk having a groove structure such as MD causes a diffraction phenomenon due to the groove, so that the return light to the photodetector PD is a superposition of the 0th-order diffracted light and the ± 1st-order diffracted light (see FIG. 18 already). As shown). Here, the 0th-order diffracted light and the ± 1st-order diffracted light are out of phase by the depth of the groove, so that the intensity of the overlapped portion is increased or decreased by interference.

  As an example, FIG. 8 shows a three-dimensional display of the intensity distribution of the return light on the detector when there is a spot in the middle of the groove on a disk having a groove depth = λ / 3. FIG. 9 also shows a two-dimensional display of the intensity distribution of the return light on the detector when there is a spot in the middle of the groove. On the other hand, in FIG. 10, the intensity distribution of the return light on the detector when the spot is shifted from the middle of the groove is displayed in a three-dimensional manner. FIG. 11 also shows a two-dimensional display of the intensity distribution of the return light on the detector when the spot is shifted from the center of the groove.

  In the intensity distribution of the return light onto the detector when there is a spot in the middle of the groove shown in FIGS. 8 and 9, in the 0th-order diffracted light, the intensity is overlapped with the area 3 to 4 (3-4), and the intensity is 4-5. Is substantially elliptical. In addition, the portion where the 0th-order diffracted light and the ± 1st-order diffracted light overlap, that is, an elliptical portion symmetrical in the radial direction sandwiching the 0th-order diffracted light and elongated in the linear direction has an intensity 4-5 region, The 5-6 region is formed in the same way. The strength of both ends of the ellipse that is long in the line direction is 4-5, and the strength of the sandwiched portion is 5-6.

  Even in the intensity distribution of the return light on the detector when the spot shown in FIGS. 10 and 11 is shifted from the middle of the groove, the intensity 4-5 overlaps with the intensity 3 to 4 (3-4) region in the 0th-order diffracted light. The region is formed in an approximately elliptical shape. On the other hand, the intensity distribution is different in a portion where the 0th-order diffracted light and the ± 1st-order diffracted light overlap, that is, an elliptical portion that is symmetrical in the radial direction across the 0th-order diffracted light and that is long in the linear direction. That is, in the overlapping portion on the left side (radial left side) toward the paper surface, the region of strength 4-5 occupies most, whereas on the right side (radial right side) the overlapping portion on the paper surface. In the part where the intensity is 5 to 6, the area of intensity 5-6 occupies most.

  As can be seen from the above, when the spot detracks from the center of the groove, the intensity changes in the overlapping portion of the 0th order diffracted light and the ± 1st order diffracted light, and only the 0th order diffracted light in the center portion. The part of is almost unchanged.

  In a general optical disc such as an MD, as already described, when tracking is removed during access or the like, the AC component (Radial Contrast :) of the total amount of return light (Pull-In) generated by the above principle is removed. The ratio of the AC component to the DC component of the return light amount) is used as a track crossing signal to identify the track count and the access direction. However, when the track pitch is narrowed, the distance of ± 1st order diffracted light is increased, and when the groove depth approaches λ / 2, the interference intensity of 0th order diffracted light and ± 1st order diffracted light is reduced. This results in a small radial contrast signal. For example, in high density MD3, in addition to narrowing the track pitch for high density, in order to ensure the characteristics of DWDD (domain wall motion detection), it is necessary to deepen the groove, and as a result, sufficient radial It is difficult to secure a contrast signal.

  As described above with reference to FIGS. 8 to 11, the change in the amount of light caused by detracking is mainly due to the overlap of the 0th order diffracted light and the ± 1st order diffracted light. By using it, it is possible to obtain a signal having the same characteristic as that of a large radial contrast even with a disk having a small radial contrast. Consider the case where the return light of the intensity distribution as shown in FIG. 12 returns on the PD.

  Normally, the radial contrast is extracted from the sum signal of (A + B + C), but most of the portion B is only the amount of DC light. On the other hand, when the sum signal of (A + C) is used, most of the portions where the 0th-order diffracted light and the ± 1st-order diffracted light overlap with most of the AC component are superimposed.

  In other words, only the 0th-order diffracted light returns to the B portion of the PD, but the overlap of the 0th-order diffracted light and the ± 1st-order diffracted light returns to the A portion and the C portion. Here, when detracking is performed, the amount of light changes mainly in the A portion and the C portion as described with reference to FIGS.

  FIG. 13 shows output change characteristics of each part of the PD when the spot is detracked from the middle of the groove. As is clear from FIG. 13, when the spot is detracked, the return light is modulated in the A part and the C part, and B is only the DC component. Therefore, in the case of the high-density MD3 with a narrow track pitch, it is understood that the modulation degree is more easily secured by using the A + C signal than using the A + B + C signal including the DC component of the B portion as the radial contrast signal.

  Further, as can be seen by referring to the spatial frequency characteristics of the pit reproduction by the objective lens shown in FIG. 14, the portion where the 0th-order diffracted light and the ± 1st-order diffracted light overlap varies depending on the track pitch. The difference in the degree of modulation of A + C becomes large. Therefore, the merit of generating a radial contrast signal with A + C is greater for a disk with a narrower track pitch. In FIG. 14, Ipp is a response characteristic of push-pull detection.

  As described above, the difference between A + B + C and A + C is large in the case of a disk with a narrow track pitch, and the merit of using A + C is great for an optical system that reads out an information signal. However, in the case of a disk having a sufficiently wide track pitch, for example, the first generation MD or the high density MD1, the changeover switch 532 in the radial contrast signal generation circuit 5-2 is set to facilitate compatibility as a signal. It is better to switch to the arithmetic unit 512 side and use A + B + C. Therefore, if the radial contrast signal is switched between A + B + C and A + C according to the type of the magneto-optical disk mounted using the radial contrast signal generation circuit 5-2 having the configuration shown in FIG. 7, the optimum radial contrast signal corresponding to the disk is used. The track count and the access direction can be accurately identified according to the type of the disk.

  Actually, the wavelength λ of the reproduction laser beam emitted from the optical head 3 is λ = 780 nm, the numerical aperture NA of the objective lens 3a is NA = 0.45, the track pitch of the high-density MD3 is track pitch = 1.2 μm, and the groove duty. The improvement of the radial contrast signal obtained from (A + C) was confirmed under the conditions of groove duty = 58.5% and groove depth = groove depth = 170 nm. In other words, the radial contrast signal Radial Contrast at (A + B + C) was 8%, whereas the radial contrast signal Radial Contrast at (A + C) was 16%, and a Radial Contrast with a double signal amplitude can be obtained. It was confirmed experimentally.

Further, a PD pattern obtained by a spot size method using a focus error signal used in a high-density-MD optical head or the like is as shown in FIG. Here, the focus error signal is generated by the following equation (6).
focus error signal == {(A + C) −B} − {(D + F) −E} (6)

Here, at the same time, a radial contrast signal can be generated by the following equation (7), (8), or (9).
Radial Contrast = A + C (7)
Radial Contrast = E + F (8)
Radial Contrast = A + C + E + F (9)

  The magneto-optical disk reproducing device described above can be summarized as follows. The groove formed in a spiral shape is tracked, and the MO signal is reproduced from the three MDs in which MO (magneto-optical) signals are recorded as information signals by detecting the polarization component of the return light. For this reason, a laser beam for reading the MO signals recorded on the three MDs is output, the laser beam is irradiated onto the groove, and a light receiving surface in which the light receiving surface is divided into a plurality of return lights from the magneto-optical disk The optical head 3 that receives the light and converts it into electrical signals for each of the plurality of light receiving surfaces, and the radial contrast signal generation circuit 5-2 that generates a radial contrast signal using the electrical signals for the plurality of light receiving surfaces of the optical head 3; Is provided. In particular, the radial contrast signal generation circuit 5-2, when the magneto-optical disk is a disk that increases the recording capacity by narrowing the track pitch and increasing the groove depth as in the high-density MD3, Stops generating the radial contrast signal by adding the signals on the light-receiving surface, and uses the sum signal of the two signals at both ends of the light-receiving surface where the 0th-order diffracted light and ± 1st-order diffracted light interfere with each other. Generate a signal.

  For this reason, the magneto-optical disk reproducing apparatus can obtain a sufficient radial contrast signal even for an optical disk having a narrow track pitch or a deep groove when a groove is used as a track. Therefore, it is possible to accurately identify the track count and the access direction.

  Next, a magneto-optical disk recording / reproducing apparatus in which a specific example of the magneto-optical disk reproducing apparatus of the present invention is applied to a reproducing unit will be described with reference to FIG.

  The magneto-optical disk recording / reproducing apparatus rotationally drives the loaded disk 90 (any one of the first generation MD, the high density MD1, and the high density MD3) by the spindle motor 21 in the CLV method or the ZCAV method. At the time of recording and reproduction, laser light is irradiated from the optical head 22 to the disk 90.

  The optical head 22 performs a high level laser output for heating the recording track to the Curie temperature during recording, and a relatively low level laser output for detecting data from reflected light by the magnetic Kerr effect during reproduction. Do. For this reason, the optical head 22 is equipped with a laser diode as a laser output means, an optical system including a polarization beam splitter, an objective lens, and the like, and a detector for detecting reflected light. The objective lens provided in the optical head 22 is held so as to be displaceable in the radial direction of the disk and in the direction of contacting and separating from the disk by, for example, a biaxial mechanism.

  A magnetic head 23 is disposed at a position facing the optical head 22 across the disk 90. The magnetic head 23 applies a magnetic field modulated by the recording data to the disk 90. Although not shown, a sled motor and a sled mechanism are provided for moving the entire optical head 22 and the magnetic head 23 in the disk radial direction.

  In the magneto-optical disk recording / reproducing apparatus 11, in addition to the recording / reproducing head system using the optical head 22, the magnetic head 23, and the disk rotation driving system using the spindle motor 21, a recording processing system, a reproducing processing system, a servo system, and the like are provided. The recording processing system includes a part that performs EFM modulation and ACIRC encoding when recording on the first generation MD, and a part that performs RLL (1-7) PP modulation and RS-LDC encoding when recording on the high-density MD1 and high-density MD3. Is provided.

  In addition, as a reproduction processing system, a part for performing demodulation and ACIRC decoding corresponding to EFM modulation at the time of reproduction of the first generation MD, and RLL (1-7) PP modulation at the time of reproduction of the high density MD1 and high density MD3. A part for performing demodulation (RLL (1-7) demodulation based on data detection using PR (1, 2, 1) ML and Viterbi decoding) and RS-LDC decoding is provided.

  Information detected as reflected light by the laser irradiation of the optical head 22 on the disk 90 (photocurrent obtained by detecting the laser reflected light with a photodetector) is supplied to the RF amplifier 24. The RF amplifier 24 performs current-voltage conversion, amplification, matrix calculation, and the like on the input detection information, and performs reproduction RF signal, tracking error signal TE, focus error signal FE, groove information (on the disc 90) as reproduction information. (ADIP information recorded by track wobbling) and the like are extracted.

  During reproduction of the first generation MD, the reproduction RF signal obtained by the RF amplifier 24 is processed by the EFM demodulator 27 and the ACIRC decoder 28 via the comparator 25 and the PLL circuit 26. The reproduced RF signal is binarized by the EFM demodulator 27 to be an EFM signal sequence, EFM demodulated, and further subjected to error correction and deinterleaving by the ACIRC decoder 28. If it is audio data, it will be in the state of ATRAC compression data at this time. At this time, the first generation MD signal side of the selector 29 is selected, and the demodulated ATRAC compressed data is output to the data buffer 30 as reproduction data from the disc 90. The reproduction data from the first generation MD is buffered in the data buffer 30 and then supplied to an audio processing unit (not shown). The audio processing unit performs audio signal processing on the reproduction data and outputs it to a speaker, headphones, or the like.

  On the other hand, at the time of reproduction of the high density MD1 or high density MD3, the reproduction RF signal obtained by the RF amplifier passes through the A / D conversion circuit 31, the equalizer 32, the PLL circuit 33, and the PRML circuit 34 to RLL (1-7 The signal is processed by the PP demodulator 35 and the RS-LDC decoder 36. The reproduction RF signal is obtained by the RLL (1-7) PP demodulator 35 by obtaining reproduction data as an RLL (1-7) code string by data detection using PR (1, 2, 1) ML and Viterbi decoding. The RLL (1-7) demodulation process is performed on the RLL (1-7) code string. Further, the RS-LDC decoder 36 performs error correction and deinterleave processing.

  In this case, the selector 29 selects the high density MD 1 or high density MD 3 side, and the demodulated data is output to the data buffer 30 as reproduction data from the disk 90. The data demodulated from the high-density MD1 and high-density MD3 side is buffered by the data buffer 30, and then, for example, data transfer is controlled and transferred to a personal computer or the like via the USB interface.

  The tracking error signal TE and the focus error signal FE output from the RF amplifier 24 are supplied to the servo circuit 37, and the groove information is supplied to the ADIP decoder 38.

  The ADIP decoder 38 limits the band of the groove information by a bandpass filter and extracts a wobble component, and then performs FM demodulation and biphase demodulation to extract an ADIP address. The extracted ADIP address, which is absolute address information on the disk, passes through the MD address decoder 39 in the case of the first generation MD and the high density MD1, and the high density MD3 address in the case of the high density MD3. It is supplied to the drive controller 41 via the decoder 40.

  The drive controller 41 executes a predetermined control process based on each ADIP address. The groove information is returned to the servo circuit 37 for spindle servo control.

  The servo circuit 37 generates spindle error signals for CLV servo control and ZCAV servo control based on an error signal obtained by, for example, integrating the phase error with the reproduction clock (PLL clock at the time of decoding) with respect to the groove information. Generate.

  Further, the servo circuit 37 receives various servo control signals based on the spindle error signal, the tracking error signal supplied from the RF amplifier 24 as described above, the focus error signal, the track jump command from the drive controller 41, the access command, or the like. (Tracking control signal, focus control signal, thread control signal, spindle control signal, etc.) are generated and output to the motor driver 42. That is, various servo control signals are generated by performing necessary processing such as phase compensation processing, gain processing, and target value setting processing on the servo error signal and command.

  The motor driver 42 generates a predetermined servo drive signal based on the servo control signal supplied from the servo circuit 37. The servo drive signal here includes a biaxial drive signal (two types of focus direction and tracking direction) for driving the biaxial mechanism, a sled motor drive signal for driving the sled mechanism, and a spindle motor drive signal for driving the spindle motor 21. It becomes. By such servo drive signals, focus control and tracking control for the disk 90 and CLV control or ZCAV control for the spindle motor 21 are performed.

  When a recording operation is performed on the disk 90, high-density data is supplied from a personal computer, for example, or normal ATRAC compressed data from an audio processing unit via the data buffer 30, a memory transfer controller, and a USB interface. Is done.

  At the time of recording for the first generation MD, the selector 43 is connected to the first generation MD side, and the ACIRC encoder 44 and the EFM modulation unit 45 function. In this case, if it is an audio signal, the compressed data from the audio processing unit via the data buffer 30 is interleaved by the ACIRC encoder 44 and added with an error correction code, and then EFM modulated by the EFM modulating unit 45. The EFM modulation data is supplied to the magnetic head driver 46 via the selector 43, and the magnetic head 23 applies a magnetic field based on the EFM modulation data to the disk 90 to record the modulated data.

  At the time of recording on the high density MD1 and high density MD1, the selector 43 is connected to the high density MD1 and high density MD3 side, and the RS-LCD encoder 47 and the RLL (1-7) PP modulation section 48 function. In this case, the high-density data sent from the memory transfer controller via the data buffer 30 is subjected to interleaving and RS-LDC error correction code addition by the RS-LCD encoder 47, and then RLL (1-7). The PP modulation unit 48 performs RLL (1-7) modulation.

  The recording data modulated into the RLL (1-7) code string is supplied to the magnetic head driver 46 via the selector 43, and the magnetic head 23 applies the magnetic field to the disk 90 based on the modulation data. Is recorded.

  The laser driver / APC 49 causes the laser diode to perform a laser emission operation during reproduction and recording as described above, but also performs a so-called APC (Automatic Laser Power Control) operation. Specifically, although not shown, a detector for laser power monitoring is provided in the optical head 22, and this monitor signal is fed back to the laser driver / APC 49. The laser driver / APC 49 compares the current laser power obtained as the monitor signal with a preset laser power and reflects the error in the laser drive signal, thereby outputting the laser power output from the laser diode. Is controlled to be stabilized at the set value. Here, as the laser power, values as the reproduction laser power and the recording laser power are set in a register in the laser driver / APC 49 by the drive controller 41.

  Based on an instruction from the system controller 18, the drive controller 41 controls each component so that each of the above operations (access, various servos, data writing, and data reading) is executed. In addition, each part enclosed with the dashed-dotted line in FIG. 16 can also be comprised as a circuit of 1 chip | tip.

  The magneto-optical disk recording / reproducing apparatus described above can achieve compatibility among the first generation MD, the high density MD1, and the high density MD3 by including the above-described configuration.

  Further, by providing a reproducing unit having the same configuration as that shown in FIG. 1 in the configuration of the RF amplifier 24, an optical disc having a narrow track pitch or a deep groove (high groove) when a groove is used as a track. A sufficient radial contrast signal can be obtained even for the density MD3). Therefore, it is possible to accurately identify the track count and the access direction.

It is a block diagram of a magneto-optical disk reproducing apparatus. It is a block diagram of the optical head of an integrated optical system. It is a figure which shows the light reception pattern on a photodetector. It is a circuit diagram of an MO signal generation circuit. It is a circuit diagram of a tracking error signal generation circuit. It is a circuit diagram of a focus error signal generation circuit. It is a circuit diagram of a radial contrast signal generation circuit. It is a figure which displays in three dimensions the intensity distribution of the return light on a detector in case a spot exists in the middle of a groove. It is a figure which displays two-dimensionally the intensity distribution of the return light on a detector in case a spot exists in the middle of a groove. It is a figure which displays in three dimensions the intensity distribution of the return light on a detector when a spot has shifted | deviated from the center of the groove. It is a figure which displays two-dimensionally the intensity distribution of the return light on a detector when a spot has shifted | deviated from the center of the groove. It is an intensity distribution figure on the photodetector which has a 3 division | segmentation light-receiving part. It is an output characteristic view from each part of the photodetector when the spot is detracked from the groove. It is a spatial frequency characteristic view of pit reproduction by an objective lens. It is a figure which shows PD pattern for spot size methods. It is a block diagram of a magneto-optical disk recording / reproducing apparatus. It is a figure which shows the specification of three types of MD. It is a figure which shows the diffraction by a groove.

Explanation of symbols

  3 optical head, 3a objective lens, 5 RF amplifier, 5-1 MO signal generation circuit, 5-2 radial contrast signal generation circuit, 5-2 tracking error signal generation circuit, 5-4 focus error signal generation circuit, 6 signal reproduction Processing circuit, 8 Address processing circuit, 9 Servo circuit, 10 Controller

Claims (2)

The information signal is reproduced from the optical recording medium on which the information signal is recorded by tracking the groove . As the optical recording medium, the first disk, a narrow track pitch with respect to the first disk, and the groove a second disc raised a recording capacity by performing deep groove of a disc reproducing apparatus for compatible reproduction,
Outputting a laser beam for reading data recorded on the optical recording medium, a plurality of laser beam irradiates to the groove, the return light from the optical recording medium, in the dividing line of the light receiving surface tangential direction An optical head that receives light at a plurality of light receiving portions that are divided in a radial direction and converts the light into electric signals for each of a plurality of light receiving surfaces;
A radial contrast signal generating means for generating a radial contrast signal using electrical signals for a plurality of light receiving surfaces of the optical head,
When the optical recording medium is the first disk, the radial contrast signal generating means generates a radial contrast signal by adding signals of all the light receiving surfaces of the light receiving unit, and the optical recording medium is the second disk . When the disc is a disc, the radial contrast signal generating means generates a radial contrast signal using a sum signal of two signals at both ends in the radial direction of the light-receiving surface, in which the 0th-order diffracted light and the ± 1st-order diffracted light interfere. generation to that disk reproducing apparatus. The radial contrast signal generating means, wherein the track pitch that generates a radial contrast signal with a sum signal of the two signals at both ends of the light receiving surface when playing narrower the second disc than 1.6μm Item 4. The disk reproducing device according to Item 1.

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