JPH08194969A - Optical disc drive - Google Patents

Abstract

PURPOSE: To detect a wobble signal accurately from both areas recorded and not recorded with data. CONSTITUTION: Light returning from an area recorded with data on an optical disc is received by respective light receiving elements A-D of a quadrant photodetector. Output signals SA-SD from the light receiving elements are subjected to matrix operation to produce signals (SA+SD) and (SB+SC). Amplitudes of the signals (SA+SD), (SB+SC) are then controlled constantly through AGC circuits 61, 62 for two independent systems and the outputs from the AGC circuits 61, 62 are subtracted to produce a wobble signal in the area recorded with data. Wobble signal for the area not recorded with data are obtained by feeding the signals (SA+SD), (SB+SC) independently to fixed gain regulation circuits 65, 66 for two systems and then subtracting the outputs therefrom. Constitutions on the AGC circuit side and the fixed gain regulation circuit side are switched depending on the recording area of the optical disc.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk apparatus for recording or reproducing data while tracking by moving an objective lens in a radial direction based on a guide groove formed in advance on a disk recording medium. .

[0002]

2. Description of the Related Art Conventionally, desired data is recorded while tracking is performed by moving an objective lens in a radial direction based on a guide groove formed in advance on a disk-shaped recording medium,
Alternatively, there is an optical disk device for reproducing. Further, in this optical disk device, it is possible to record information only once by converging a light beam on the disk-shaped recording medium and changing the optical properties of the recording layer in the guide groove to form pits. So-called CD-R that uses a recordable optical disc
(CD-Recordable) There is an optical disk device.

The guide groove previously formed on the write-once type optical disc is called a pre-groove. For example, as shown in FIG. 9A, the pregrooves PG _{1 to} PG ₄ are formed on the write-once optical disc 7. At the time of recording and reproducing data, the pre-grooves PG _{1 to} PG ₄ are used to control the tracking servo and the spindle servo. Further, as shown in FIG. 9B, a rotation synchronizing signal for controlling the spindle motor is recorded as a wobble of the pre-groove, that is, a wobble. This wobble signal is a carrier signal of 22.05 kHz frequency-modulated by address information, and this wobble signal is recorded by causing the groove to meander in the radial direction of the optical disc 7. The address information is ATIP
It is called (Absolute Time In Pre-groove) and is recorded as time information indicating the absolute address on the optical disc. At the time of data recording, address information is obtained from the ATIP, and spindle servo CLV (constant linear velocity) control is performed.

FIG. 10 shows a schematic structure of the CD-R optical disk device.

First, at the time of recording data on an optical disk, data such as audio sent from an external host computer or the like is input from a signal input terminal 43 via an interface circuit. This data is sent to the data encoder 28, encoded, and converted into a recording signal. This recording signal is sent to the laser modulation circuit 29. In the laser modulation circuit 29, an optical means for converting the recording signal into a laser light output and outputting a light beam,
It is sent to a so-called optical pickup.

Specifically, the laser light output is emitted from the laser diode 1. The light beam emitted from the laser diode 1 is collimated by the collimation lens 2 and guided to the objective lens 6 via the grating (diffraction grating) 3 and the beam splitter 4, and the objective lens 6 causes the light beam on the optical disk 7. Collected. Here, at the time of recording data, the intensity of the laser output irradiated onto the optical disc 7 is controlled according to "1" or "0" of the data, and desired data is recorded on the optical disc 7.

A part of the light beam incident on the beam splitter 4 is separated by the beam splitter 4 and incident on the laser monitor 5. A part of the light beam incident on the laser monitor 5 is sent to the monitor head amplifier 30, converted into a voltage, and further sent to the automatic power control (APC) circuit 31. The APC circuit 31 uses the signal from the monitor head amplifier 30 to perform control so that the emission power of the light beam emitted from the laser diode 1 is constant without being affected by external factors such as temperature. The control signal from the APC circuit 31 is sent to the laser modulation circuit 29. In the laser modulation circuit 29, the emission power of the light beam emitted from the laser diode 1 is kept constant by using the control signal from the APC circuit 31.

On the other hand, the reflected light of the light beam irradiated on the optical disk 7 is incident on the beam splitter 4 via the objective lens 6. The beam splitter 4 guides the incident reflected light to the multi-lens 8. The multi-lens 8 is composed of a cylindrical lens (cylindrical lens), a condenser lens, and the like, and condenses the incident reflected light on the photodetector 9.

The output from the photo detector 9 is converted into a voltage by the head amplifier 10 and output to the matrix circuit 11. In this matrix circuit 11,
By performing a predetermined addition and subtraction on the output from the head amplifier 10, the tracking error signal TE,
Focus error signal FE and push-pull signal PP
Generate

The tracking error signal TE and the focus error signal FE are sent to the corresponding phase compensation circuits 12 and 13, respectively. The phase compensation circuit 12 adjusts the signal level of the tracking error signal to 0 level, and the adjusted signal is sent to the drive circuit 14. The drive circuit 14 uses the signal from the phase compensation circuit 12 to track the tracking actuator 1.
By operating 6 the objective lens 6 is controlled to move in the radial direction of the optical disc 7 so that the light beam accurately traces the track on the optical disc 7. Further, the phase compensation circuit 13 adjusts the signal level of the focus error signal to 0 level, and the adjusted signal is sent to the drive circuit 15. In this drive circuit 15, by operating the focus actuator 17 using the signal from the phase compensation circuit 13, the objective lens 6 is set on the optical disk 7 so that the light beam is accurately focused on the optical disk 7. On the other hand, the movement is controlled in the vertical direction.

Further, the tracking error signal TE
Are also sent to the thread phase compensation circuit 32. In the sled phase compensation circuit 32, the drive circuit 33 that drives the sled motor 34 so that the signal level of the low frequency component of the tracking error signal TE becomes 0 level.
To adjust. The drive circuit 33 uses the signal from the sled phase compensation circuit 32 to drive the sled motor 3
By driving 4, the position of the optical pickup arranged on the sled mechanism 44 is controlled to move.

Further, the push-pull signal PP output from the matrix circuit 11 is the wobble detection circuit 2
It is output to 1. The wobble detection circuit 21 detects the wobble signal and outputs it to the ATIP demodulator 22. The ATIP demodulator 22 detects the ATIP and ATIP read clock signals from the detected wobble signal, and sends the ATIP and ATIP read clock signals to the ATIP decoder 23.
In this ATIP decoder 23, ATIP and ATIP
The address information is reproduced using the read clock signal. The reproduced address information is sent to the CPU 24. The CPU 24 can know the track address or the like currently being reproduced from the address information.

The wobble signal detected by the wobble detection circuit 21 and the ATIP read clock signal detected by the ATIP demodulator 22 are also output to the spindle servo circuit 25. This spindle servo circuit 2
In 5, the spindle motor 27 is driven via the motor driver 26 using the supplied wobble signal and ATIP read clock signal. At this time, the spindle servo circuit 25 controls the wobble signal detected by the wobble detection circuit 21 to have a constant frequency of 22.05 kHz, or an ATIP read clock signal output from the ATIP modulator 22. Is controlled to a constant frequency of 6.35 kHz.

Further, at the time of reproducing data, the return light of the light beam irradiated on the optical disk 7 as described above is received by the photodetector 9, and the received light amount is sent to the matrix circuit 11 via the head amplifier 10. send.

The matrix circuit 11 generates a tracking error signal TE, a focus error signal FE, and an RF signal which is a signal component of recording information. The tracking error signal TE and the focus error signal F
E is sent to each constituent element similar to the above, and is used for tracking servo and focus servo, respectively.

The RF signal output from the matrix circuit 11 is sent to the binarizing circuit 18 to be binarized and P
It is sent to the LL circuit 19. In this PLL circuit 19, a clock signal is reproduced from the supplied binarized signal, and this clock signal is sent to the decoder circuit 20 together with the binarized signal. In the decoder circuit 20, the binarized signal is decoded using the clock signal. As a result, the data signal and the subcode are reproduced. The reproduced data signal is output from the output terminal 42. Further, the sub code is sent to the CPU 24. This CP
In U24, various controls are performed using the sent subcode.

The clock signal reproduced by the PLL circuit 19 is input to the spindle servo circuit 25 as a read clock of the RF signal and compared with the reference clock signal. This compared output is sent to the motor driver 26 as a rotation error signal during data reproduction. The motor driver 26 controls the drive of the spindle motor 27 using the rotation error signal.

[0018]

By the way, when the objective lens arranged in the optical pickup is in the mechanical neutral position, the spot of the light received on the photodetector 9 in the optical pickup (reflected from the optical disk is reflected. It is desirable that each of the spots of the light condensed and collected) is also located at the center on the photodetector 9. Therefore, at the time of manufacturing the optical pickup, the mounting position of the photodetector 9 is adjusted so that the spot is located at the center on the photodetector 9 when the objective lens is at the mechanical neutral position.

However, even if the mounting position of the photodetector 9 is adjusted at the time of manufacturing the optical disc device, the mounting position of the photodetector 9 is displaced due to, for example, temperature change or aging (aging) after shipping. As a result, the position of the spot may be displaced. When the position of the spot is displaced with respect to the photodetector in this way, the RF signal largely leaks into the push-pull signal, which deteriorates the S / N of the wobble signal and makes the detection of the wobble signal extremely difficult. It will be difficult.

Therefore, in view of the above situation, the present invention provides an optical disk device capable of always accurately detecting a wobble signal.

[0021]

An optical disk device according to the present invention has been proposed in order to achieve the above-mentioned object, and an objective lens using a guide groove formed meandering in the radial direction of the optical disk. Is a device that records or reproduces data while performing tracking control by moving in a radial direction and generates a signal based on the meandering of the guide groove, and is divided into two corresponding to the radial direction of the optical disc. Two-division light detecting means for detecting the amount of light incident on each light-receiving portion, and a light beam focused on an information recording surface on the optical disc and return light from the optical disc divided into two. The optical system for condensing on the light receiving portion of the light detecting means and the amplitude of the detection output obtained by receiving the return light from the data recorded area on the optical disk at each light receiving portion of the two-divided light detecting means are independent. The gain control means of the two systems for making the output constant, and the detection output obtained by receiving the return light from the data unrecorded area on the optical disc at each light receiving portion of the two-divided light detection means are independently adjusted to the fixed gain. To do 2
A fixed gain adjusting means for the system, and a switching selecting means for switching and selecting between a subtractive calculating force obtained by subtracting the outputs of the gain controlling means of the two systems and a subtractive calculating force obtained by subtracting the outputs of the fixed gain adjusting means of the two systems. It is characterized in that the output of the switching selection means is taken out as a signal based on the meandering of the guide groove.

Here, the optical system focuses the light beam from the light source as a main beam and a sub beam on the optical disc, and the two-division light detecting means receives the return light of the main beam from the optical disc. The tracking control is performed by canceling the offset of the detection output signal detected by the detection output signal of the sub beam. Further, the guide groove is modulated in the radial direction of the optical disc based on time information indicating the absolute address on the optical disc. Further, the optical disc is a write-once optical disc.

In the optical disk device of the present invention, the signal reproduced from the optical disk is passed through the high frequency band, and the light beam is emitted based on the pulse intervals of the pulse signals obtained by comparison at a predetermined slice level. A recording area detecting means for detecting a data recorded area and a data unrecorded area on the optical disc is provided, and the switching selection means makes the switching selection based on the detection output of the recording area detection means. There is.

[0024]

According to the present invention, the signal based on the meandering of the guide groove on the optical disk subtracts the two detection outputs obtained by receiving the return light from the optical disk by the two light receiving portions of the two-division light detecting means. Since it is taken out as an output, the return light from the data recorded area on the optical disc
The amplitudes of the detection outputs received by the respective light receiving portions of the divided light detection means are independently made constant by the two systems of gain control means, and the two outputs from the two systems of gain control means are subtracted from each other. Then, the RF component due to the recording data in the data recorded area will not leak as an error. Similarly, with respect to the return light from the data unrecorded area on the optical disc, the detection output obtained by receiving light at each light receiving portion of the two-division light detecting means is independently adjusted by the two-system fixed gain adjusting means, It suffices to subtract the outputs of these two systems of fixed gain adjusting means. Therefore, in the present invention, the guide groove is obtained from both the return light from the data recorded area and the return light from the data unrecorded area. It is possible to generate an accurate signal based on the meandering of.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to the drawings. The basic configuration of the optical disk device of the embodiment of the present invention shown in FIG.
The description of the same components as those in FIG. 10 is omitted, and only the main parts will be described in the following description.

The optical disk apparatus of the embodiment of the present invention performs tracking control by moving the objective lens 6 in the radial direction using a guide groove (pre-groove) formed by wobbling in the radial direction of the optical disk 7. A device for recording or reproducing data while generating a wobble signal of the pre-groove, which is divided into two light receiving portions corresponding to the radial direction of the optical disc 7, as shown in FIGS. 1 and 5. And a photodetector 9 as a two-divided light detecting means for detecting the amount of light incident on each light receiving portion, and a light beam is condensed on an information recording surface on the optical disc 7 and return light from the optical disc 7 is collected. The photo detector 9
Optical pickup for collecting light on the light receiving part of the optical disc 7
AGC (auto gain control) circuit which is a two-system gain control means for independently stabilizing the amplitude of the detection output obtained by receiving the return light from the above data recorded area at each light receiving portion of the photodetector 9. 61,
62 and two systems of fixed gain adjusting circuits 65 and 66 for independently adjusting the detection output obtained by receiving the return light from the data unrecorded area on the optical disk 7 at each light receiving portion of the photodetector 9 to a fixed gain. And the above two lines of AG
It has a selector 69 as a switching selection means for switching and selecting a subtraction calculation force obtained by subtracting the outputs of the C circuits 61 and 62 and a subtraction calculation force obtained by subtracting the outputs of the fixed gain adjusting circuits 65 and 66 of the two systems. , The selector 69
Is output as a wobble signal of the pre-groove.

Here, in the optical disc apparatus of this embodiment, a so-called differential push-pull (DPP) system is used as the tracking servo system.

That is, in the DPP method, unlike the usual push-pull method in which tracking servo is performed using only one beam, the light beam emitted from the laser diode is a main beam (0th order light) and a sub beam (±). This is a system in which tracking servo is performed by dividing the light beam into three light beams (primary light) and placing the main beam on the groove on the optical disk and the sub-beam on the land on the optical disk. The three light beams radiated on the optical disc are reflected by the optical disc, and the main beam is radiated onto a four-division photodetector.
The two sub-beams are received on the corresponding two-divided photodetectors. The tracking error signal is obtained by adding and subtracting the detection output signals of these three received lights as described later. According to this DPP method, the main beam and the sub beam are out of phase with each other by 180 degrees, but they have the same phase with respect to the skew and the beam offset. Therefore, if the main beam and the sub beam are subtracted, the skew and the beam The feature is that the offset can be canceled.

More specifically, since this DPP method is adopted, in the optical disk device of this embodiment, the light beam emitted from the laser diode 1 is divided into a main beam (0th order light) and a sub beam by the grating 3. The light beam is divided into three light beams (± first-order light), and these three light beams that have passed through the beam splitter 4 are condensed on the optical disk 7 by the objective lens 6.

That is, as shown in FIG. 2 showing the light beam irradiated on the optical disk 7, the optical disk 7 is
Pre-grooves formed for the pits and lands where the pits are not formed are the pre-grooves PG.
₁ , land LD ₁ , pre-groove PG ₂ , land L
D ₂ , pregrooves PG ₃ , ... Are alternately formed. Of the three light beams condensed by the objective lens 6, the main beam (0th order light) located at the center is on the pre-groove (for example, the pre-groove PG).
_The upper two beams are focused and irradiated, and the other two sub-beams (±
The primary light is on the land (eg, land LD ₁ , LD
₂ ) is focused and irradiated. Note that the example of FIG. 2 shows the beam spot in the state where the focus servo is applied.

As shown in FIG. 3 specifically showing the light spot condensed on the photodetector 9, the respective reflected lights of the three light beams irradiated on the optical disk 7 are reflected by the beam splitter 4 to the multi-lens 8. After being guided to, the reflected light of the main beam is divided into four photodetectors 9.
₂ , the reflected light of the sub-beam is collected and received by the corresponding two-divided photodetector 9 ₁ or 9 ₃ , respectively. The photodetector 9 ₂ which receives the reflected light of the main beam is composed of four light receiving elements A, B, C and D, and the photodetector 9 ₁ which receives the reflected light of the sub beam is composed of two light receiving elements E and F, The photo detector 9 ₃ comprises two light receiving elements G and H. Photo detector 9 ₂ above
The light receiving elements A and D, and the light receiving elements B and C are arranged in the radial direction of the optical disk 7. Further, the light receiving element E and the light receiving element F of the photo detector 9 _{1 and} the light receiving element G and the light receiving element H of the photo detector 9 ₃ are arranged in a direction orthogonal to the radial direction of the optical disk 7. The track direction of the optical disk 7 is the direction shown by the double-headed arrow T _R.

The outputs from the three photodetectors are converted into voltages by the head amplifier 10 shown in FIG. 1 and output to the matrix circuit 51. In the matrix circuit 51, the tracking error signal TE and the focus error signal F are added to the output from the head amplifier 10 by performing addition and subtraction as described later.
In addition to the E and RF signals, the wobble detection circuit 53 in the subsequent stage generates and outputs a signal used for generating the push-pull signal PP as described later.

Here, the generation of the tracking error signal TE in the matrix circuit 51 will be specifically described with reference to FIG.

First, an output signal (SA + SD) obtained by adding the output signal SA from the light receiving element A for receiving the reflected light of the main beam and the output signal SD from the light receiving element D,
An output signal (SB + S) obtained by adding the output signal SB from the light receiving element B and the output signal SC from the light receiving element C.
The difference signal (SA + SD) − (SB + SC) from C) is generated by the adder 101. Further, a difference signal (SE-SF) between the output signal SE from the light receiving element E and the output signal SF from the light receiving element F that receive the reflected light of one of the sub-beams.
Is generated by the adder 100, and a difference signal (SG-SH) between the output signal SG from the light receiving element G that receives the reflected light of the other sub beam and the output signal SH from the light receiving element H is the adder 102. Is generated by. Difference signal (SA + SD)
-(SB + SC), the difference signal (SE-SF), and the difference signal (SG-SH) are added and subtracted in the adder 103,
As a result, the tracking error signal TE is obtained.
That is, the tracking error signal TE is obtained by the following equation (1).

TE = {(SA + SD) − (SB + SC)} − {(SE + SG) − (SF + SH)} (1) In the matrix circuit 51, the focus error signal FE is It is calculated by the equation (2).

FE = (SA + SC)-(SB + SD) (2) The tracking error signal TE and the focus error signal FE are sent to the corresponding phase compensation circuit 12 or 13 in FIG. The compensation circuit 12 or 13 respectively performs phase compensation and outputs the tracking signal and the focus signal. Then, the tracking signal and the focus signal are sent to the corresponding drive circuits 14 and 15, respectively.
Thus, the tracking actuator 16 and the focus actuator 17 corresponding to each are controlled to move.

Further, in the matrix circuit 51, the tracking error signal TE and the focus error signal FE are
In addition, an RF signal, which is a signal component of recorded information, is generated during signal reproduction. This RF signal is obtained by the following equation (3).

RF = SA + SB + SC + SD (3) The RF signal output from the matrix circuit 51 is
It is sent to the binarization circuit 18 and also to a recording area detection circuit 52 described later.

Further, the push-pull signal PP can be obtained by the following equation (4).

PP = (SA + SD)-(SB + SC) (4) By the way, also in the above-mentioned optical disc apparatus of this embodiment, the objective lens 6 disposed in the optical pickup is arranged in the same manner as the above-mentioned conventional example. Is in a mechanical neutral position, the spot of light received on the photodetector 9 in the optical pickup (the spot of the light reflected and condensed from the optical disk) is also located in the center on the photodetector 9. Is desirable. Therefore, at the time of manufacturing the optical pickup, the mounting position of the photodetector 9 is adjusted so that the spot is located at the center of the photodetector 9 when the objective lens 6 is at the mechanical neutral position.

Thus, if the objective lens 6 is in the mechanical neutral position and the spot is located at the center on the photodetector 9 ₂ as shown in FIG. 4A, the light receiving element A of the photodetector 9 ₂ is detected. And D and (SA + SD) and (SB + SC) obtained by adding the respective output signals of the light receiving elements B and C, the amplitudes of the RF components are the same as shown in (b) and (c) of FIG. Become.

However, as described above, even if the mounting position of the photodetector 9 is adjusted at the time of manufacturing the optical disk device, the photodetector 9 may be changed due to, for example, temperature change or aging (change with time) after shipment.
If the position of the spot is displaced as a result of the mounting position of the disc being displaced as a result, as shown in FIG.
D) and (SB + SC) have different amplitudes of RF components, as shown in (e) and (d) of FIG. As described above, when the amplitude of the RF component differs between (SA + SD) and (SB + SC), the RF component remains in the push-pull signal PP and an accurate wobble signal is detected, as shown in (g) of FIG. Can't do it.

Therefore, as shown in (h) and (i) of FIG. 4, the optical disc apparatus of this embodiment independently sets the amplitudes of the RF components of (SA + SD) and (SB + SC). By adjusting, (SA + SD) and (S
The amplitudes of the RF components of (B + SC) are made equal to cancel the RF components in the push-pull signal PP as shown in (i) of FIG. 4 so that an accurate wobble signal can be detected.

The optical disk device of this embodiment has the structure shown in FIGS. 1 and 2 in order to cancel the RF component in the push-pull signal PP as described above. That is, in the apparatus of this embodiment, the difference from the configuration of FIG. 10 described above is that the matrix circuit 51 and the wobble detection circuit 53 have the configuration as shown in FIG. 5, and the recording area detection circuit 52 described later is provided. That is.

In FIG. 5, the input terminal 70A of the matrix circuit 51 is supplied with the output signal SA from the light receiving element A of the photodetector 9 ₂ via the head amplifier 10, and similarly the input terminal 70D is provided with the light receiving element D. From the light receiving element B to the input terminal 70B, and the output signal SC from the light receiving element C to the input terminal 70C. This matrix circuit 51 is different from the matrix circuit 11 of FIG.
Instead of outputting the push-pull signal PP obtained by the equation (4), the arithmetic circuit 81 does not output the output signals SA.
~ SD is used to perform the operations of (SA + SD) and (SB + SC) when the push-pull signal PP is generated, and the obtained (SA + SD) signal and (SB + SC) signal are output. . Further, the adder circuit 82 of the matrix circuit 51 generates an RF signal by performing the operation of the equation (3) using the output signals SA to SD,
Output. Note that the structure for generating the tracking error signal TE and the focus error signal FE provided inside the matrix circuit 51 is omitted. The (SA + SD) signal and the (SB + SC) signal from the matrix circuit 51 are the wobble detection circuit 53.
And the RF signal is sent to the binarizing circuit 18 via a terminal 71 and a recording area detecting circuit 52 described later.
Also sent to.

As shown in FIG. 5, the wobble detection circuit 53
The (SA + SD) signal supplied to is sent to an AGC (auto gain control) circuit 61 for automatically controlling the amplitude, and the (SB + SC) signal is A
It is sent to the GC circuit 62. These AGC circuits 61 and 6
2 operates independently of each other, and each is configured as shown in FIG.

In FIG. 6, the signal supplied to the input terminal 90 of the AGC circuit is amplified by a GCA (gain control amplifier) 91 and then full-wave rectified by a full-wave rectifier 93. The output of this full-wave rectifier 93 is
It is sent to the comparator 94, and is compared with a predetermined reference voltage V _ref in the comparator 94. The comparison result of the comparator 94 is sent to the switch 99 as a switch control signal. In this embodiment, the output of the full-wave rectifier 93 of the comparator 94 is the predetermined reference voltage V _ref.
A switch control signal is output which turns on the switch 99 when the above condition occurs and turns off when less than the condition.

The switch 99 has a constant current source 96 for the current I ₂ connected to one terminal a side and a constant current source 97 for the current I ₁ connected to the other terminal b side. A common connection point between the other terminal b and the constant current source 97 has a capacitance C in which one terminal is grounded and the other terminal is connected to the high impedance gain control terminal of the GCA 91.
Is also connected to the other terminal of the capacitor 98.

Therefore, when the switch 99 is turned off, the electric charge of the capacitor 98 flows through the constant current source 97, and the voltage of the gain control terminal of the GCA 91 becomes low. On the other hand, when the switch 99 is turned on, a current of I ₂ -I ₁ flows through the capacitor 98 to accumulate charges, and the voltage of the gain control terminal of the GCA 91 becomes high.

The GCA 91 raises or lowers the gain of the signal supplied from the input terminal 90 according to the voltage of the gain control terminal. For example, when the voltage of the gain control terminal drops, the signal is supplied from the input terminal 90. When the voltage of the gain control terminal is increased, the gain of the signal supplied is increased, and the gain of the signal supplied from the input terminal 90 is decreased and output.

In this way, the signal input from the input terminal 90 is subjected to constant gain control and sent to the subsequent stage configuration via the output terminal 92.

That is, in the AGC circuit of FIG. 6, the full-wave rectified signal of the input signal is compared with a predetermined reference voltage V _ref, and the gain of the input signal is controlled to be constant according to the comparison result. Thus, a signal having a constant amplitude is output from the output terminal 92.

In FIG. 5, the wobble detection circuit 53 is
The gain control is performed by the AGC circuit 61 inside (S
The signal of (A + SD) is sent to the adder circuit 64, and the
The gain is controlled by the C circuit 62 (SB + S
The signal C) is inverted by the inverting circuit 63 and sent to the adding circuit 64, and these signals are added by the adding circuit 64. That is, in the addition circuit 64, the above (SA
+ SD) and the signal obtained by inverting the signal of (SB + SC) are added to perform the calculation of the equation (4),
Therefore, the push-pull signal PP is obtained from the adder circuit 64.

As described above, in the optical disc apparatus of this embodiment, as shown in (h) and (i) of FIG. 4, the amplitudes of the RF components of (SA + SD) and (SB + SC) are independent of each other. Adjust (SA + SD) and (S
Since the amplitudes of the RF components of (B + SC) are made equal to each other, even if the mounting position of the photodetector 9 is displaced after shipment of the device due to, for example, temperature change or aging, the position of the spot is also displaced. , RF in the push-pull signal PP as shown in (i) of FIG.
It is possible to cancel the components, and thus to detect an accurate wobble signal.

By the way, since the optical disc 7 is a write-once disc as described above, the signal input to the wobble detection circuit 53 is reproduced from a recorded area on the optical disc where data has already been recorded. It may be a signal reproduced from an unrecorded area on the optical disc in which data has not been recorded yet. In the signal reproduced from this unrecorded area, R as described above is added.
The F component is not included. Therefore, in the optical disc apparatus of the present embodiment, fixed gain adjustment is performed for each of the (SA + SD) and (SB + SC) signals based on the signal reproduced from this unrecorded area.

Therefore, as shown in FIG. 5, (SA + SD) and (S) based on the signal reproduced from the unrecorded area are recorded.
B + SC) signals are adjusted to fixed gains independently by fixed gain adjustment circuits 65 and 66, and then (SA + SD) signals are directly added to the adder circuit 68 and (SB + SC) signals. Is inverted by the inversion circuit 67 and then added by the addition circuit 6.
Sent to 8. The signal reproduced from this unrecorded area is also
Similarly to the above, in the addition circuit 68, the above (SA + SD)
By adding the signal of (4) and the signal obtained by inverting (SB + SC), the operation of the equation (4) is performed, and therefore, the push-pull signal PP is obtained from the adding circuit 64. This push-pull signal PP is the same as the above (SA
Since the + SD) and (SB + SC) signals are independently adjusted in gain, they can be extracted as an accurate wobble signal.

However, as shown in FIG. 5, in the apparatus of this embodiment, the matrix circuit 51 to the wobble detection circuit 53 are used.
Regardless of whether the signal sent to is a reproduction signal from the recorded area or a reproduction signal from an unrecorded area,
Both AGC circuits 61 and 62 and fixed gain adjusting circuit 6
5 and 66. For this reason,
In the device of this embodiment, the adder circuit 6 of the wobble detection circuit 53 is used.
The outputs of 4 and 68 are supplied to a selector 69, and whether the signal input to the matrix circuit 51 is a signal reproduced from a recorded area or a signal reproduced from an unrecorded area is supplied to the selector 69. The switching is performed according to the determination result of.

In the apparatus of the present embodiment, whether the reproduced area of the optical disk is the recorded area or the unrecorded area, that is, the signal input to the matrix circuit 51 is the signal reproduced from the recorded area. Or the signal reproduced from the unrecorded area is determined by the matrix circuit 51.
The RF signal obtained from the adder circuit 82 is used.

In order to make the determination, the RF signal from the adding circuit 82 of the matrix circuit 51 is sent to the recording area detecting circuit 52.

The recording area detection circuit 52 specifically has the configuration shown in FIG.

Here, when the RF signal input to the input terminal 110 of the recording area detecting circuit 52 is a signal reproduced from the recording area in which data is recorded as shown in FIG. 8A. , The signal level is changing, but in the case of the signal reproduced from the unrecorded area, the signal level is almost constant. The RF signal shown in (a) of the figure becomes an output signal having a constant signal level centered on 0 level as shown in (b) of the figure by passing through the high-pass filter (HPF) 111.

The output signal from the HPF 111 is input to the comparator 112. The comparator 112 compares the output signal of the HPF 111 at a predetermined slice level. As a result, as shown in (c) of FIG. 8, during reproduction at the standard speed, the period of the recording area is 3
The signals are "0" (L level) and "1" (H level) signals corresponding to the pulse width signals of T to 11T, and the pulse width is longer than the period 11T or there is no pulse in the unrecorded area. An output signal of "1" (H level) is obtained. The output signal from the comparator 112 is input to the pulse width detection circuit 1137.

From the pulse width detection circuit 113, the pulse width of the output signal from the comparator 112 is 1 cycle.
When it is shorter than 1T, it is "1" indicating that it is a reproduction signal from the recording area, and when the pulse width of the output signal from the comparator 112 is longer than the period 11T or when there is no pulse, it is a reproduction signal from an unrecorded area. A detection signal that is “0” indicating “0” is output. This detection signal is shown in (d) of FIG. At this time, in the pulse width detection circuit 113, it is determined whether the output signal from the comparator 112 is a signal in the recording area, for example, 1
If the detection is performed in 0 μs, the detection signal is output with a delay of 10 μs at the boundary between the recorded area and the unrecorded area. That is, the pulse width detection circuit 113 can determine whether or not it is the recording area only by the delay of 10 μs.

As described above, the recording area detection circuit 52 of the apparatus of the present embodiment discriminates whether or not the recording area is based on the time axis of the RF signal, that is, the pulse width, thereby accurately and quickly. The recorded area and the unrecorded area can be detected. The output of the recording area detection circuit 52 is
A switching control signal is sent to the selector 69 of FIG. 5 via the output terminal 114.

The signal switched by the selector 69 in FIG. 5 is sent to the ATIP modulator 22 and the spindle servo circuit 25 in FIG. 1 via the output terminal 72 of the wobble detection circuit 53 as a wobble signal.

As described above, in the optical disk device of the present embodiment, the fluctuation component due to the temperature change and the aging change (aging change) can be removed from the push-pull signal, so that an accurate wobble signal can be detected, and therefore the device Improves reliability.

When performing a seek operation, for example,
Since the track jump is performed, the spot position may be displaced. However, according to the optical disc apparatus of the present embodiment, the wobble signal is quickly generated after the optical pickup is moved by the seek operation. As a result, the seek time can be shortened as a result.

[0068]

As is apparent from the above description, the optical disk device according to the present invention obtains the return light from the data recorded area on the optical disk by receiving light from each light receiving portion of the two-division light detecting means. The amplitude of the detection output is made constant independently of each other, and the detection output obtained by receiving the return light from the data unrecorded area on the optical disc by each light receiving portion of the two-division light detection means is independently fixed gain. By adjusting to, the accurate wobble signal based on the meandering of the guide groove can be detected from both the return light from the data recorded area and the return light from the data unrecorded area.

Further, the device of the present invention collects the light beam from the light source as the main beam and the sub beam on the optical data,
The split light detection means cancels the offset of the detection output signal detected by receiving the return light of the main beam from the optical disc by the detection output signal of the sub beam to perform tracking control, thereby performing the tracking control of the objective lens in the optical system. It is possible to accurately detect an error during movement.

Further, the guide groove is modulated in the radial direction of the optical disk based on the time information indicating the absolute address on the optical disk, so that if the wobble signal based on the meandering of the guide groove is demodulated, the absolute value on the optical disk is changed. The address can be known, and the accurate tracking position can be detected.

Further, the detection of the data recorded area and the data unrecorded area on the optical disc irradiated with the light beam is obtained by comparing the signals reproduced from the optical disc at a predetermined slice level. It can be performed based on the pulse interval of the pulse signal.

[Brief description of drawings]

FIG. 1 is a block circuit diagram showing a schematic configuration of an optical disk device of an embodiment of the present invention.

FIG. 2 is a diagram showing irradiation light of a light beam on an optical disc.

FIG. 3 is a diagram showing a specific configuration of an optical pickup and a photodetector.

FIG. 4 is a diagram for explaining a cause of S / N deterioration of a wobble signal and a countermeasure therefor.

FIG. 5 is a block circuit diagram showing a configuration of a main part of the device of this embodiment.

FIG. 6 is a block circuit diagram showing a specific configuration of an AGC circuit.

FIG. 7 is a block circuit diagram showing a specific configuration of a recording area detection circuit.

FIG. 8 is a waveform diagram showing a signal waveform in each part of the recording area detection circuit.

FIG. 9 is a diagram showing pregrooves and wobbles on an optical disc.

FIG. 10 is a block circuit diagram showing a schematic configuration of a conventional optical disc device.

[Explanation of symbols]

 51 matrix circuit 52 recording area detection circuit 53 wobble detection circuit 61, 62 AGC circuit 63, 67 inversion circuit 64, 68, 82 addition circuit 65, 66 fixed gain adjustment circuit 69 selector 81 arithmetic circuit

Claims (5)

[Claims] 1. A guide groove formed by meandering in the radial direction of an optical disk is used to move or move the objective lens in the radial direction to record or reproduce data while performing tracking control, and meandering the guide groove. In the optical disc device for generating a signal based on the above, there is provided a light receiving part which is divided into two parts corresponding to a radial direction of the optical disc, and a two-part light detecting means for detecting the amount of light incident on each light receiving part, and a light beam. And an optical system for condensing the return light from the optical disc on the light receiving part of the two-division light detecting means, and the return light from the data recorded area on the optical disc. The above 2
The gain control means of two systems for independently stabilizing the amplitude of the detection output received by each light receiving portion of the split light detection means, and the return light from the data unrecorded area on the optical disc
The detection output obtained by receiving light at each light receiving portion of the split light detection means
Two systems of fixed gain adjusting means for independently adjusting fixed gains, a subtraction calculation force obtained by subtracting outputs of the two systems gain control means, and a subtraction calculation force obtained by subtracting outputs of the two systems of fixed gain adjustment means. An optical disc device comprising: a switching selection means for switching and selecting between and, and an output of the switching selection means is taken out as a signal based on the meandering of the guide groove. 2. The optical system focuses a light beam from a light source as a main beam and a sub beam on the optical disc, and the two-division light detecting means receives return light of the main beam from the optical disc. 2. The optical disc apparatus according to claim 1, wherein the offset of the detected detection output signal is canceled by the detection output signal of the sub beam to perform the tracking control. 3. The optical disk device according to claim 1, wherein the guide groove is modulated in a radial direction of the optical disk based on time information indicating an absolute address on the optical disk. 4. The optical disk device according to claim 1, wherein the optical disk is a write-once optical disk. 5. Data recording on an optical disk irradiated with the light beam based on the pulse interval of pulse signals obtained by comparing a signal reproduced from the optical disk at a high frequency and comparing at a predetermined slice level. 2. A recording area detecting means for detecting a recorded area and an unrecorded area of data, wherein the switching selection means makes a switching selection based on a detection output of the recording area detecting means.
The optical disk device described.