JP3566717B1 - Optical disk drive - Google Patents

Abstract

【Task】 Performs stable recording and reproduction on the optical disk without increasing the size.
A first photoelectric conversion signal Sc1 is adjusted with a first gain by a first signal adjustment circuit c2, and a second photoelectric conversion signal Sc10 is adjusted with a second gain by a second signal adjustment circuit c11. Is done. The gain determining circuit determines the first gain based on one of the amplitude and the average level of the output signal of the first signal adjustment circuit, and determines one of the amplitude and the average level of the output signal of the second signal adjustment circuit. Is determined based on the second gain. In this case, the output signal Swb of the difference signal generation circuit c18 is determined by selecting one of the amplitude and the average level of the output signal of each signal adjustment circuit and determining each gain according to the signal characteristics of each photoelectric conversion signal. Can be efficiently reduced.
[Selection diagram] FIG.

Description

The present invention relates to an optical disc device, and more particularly, to an optical disc device that irradiates a recording surface of an optical disc with light to record and reproduce information.

  In recent years, with the advance of digital technology and the improvement of data compression technology, as a medium for recording user data such as music, movies, photographs, and computer software, a CD (compact disc) or data equivalent to about seven times the size of a CD is used. Optical disks, such as DVDs (digital versatile discs), which can record data on a disk having the same diameter as a CD, have been attracting attention. Became.

  In an optical disc, information is recorded by the length of each of a mark area and a space area having different reflectances and a combination thereof. Therefore, when information is recorded on the optical disk, the power of the laser light emitted from the light source (hereinafter, also referred to as “light emission power”) is controlled so that a mark area and a space area are respectively formed at predetermined positions.

  In write-once optical discs such as CD-R (CD-recordable), DVD-R (DVD-recordable), and DVD + R (DVD + recordable) containing an organic dye on the recording surface, the light emission power is increased when forming a mark area, Is heated and melted, and the disk substrate portion in contact therewith is altered and deformed. On the other hand, when the space area is formed, the light emission power is set to be as low as during reproduction so that the disc substrate is not deteriorated or deformed. As a result, the reflectance in the mark area is lower than that in the space area. Such a method of controlling the light emission power is also called a single pulse recording method. The light emission power when forming the mark area is also called write power, and the light emission power when forming the space area is also called bottom power.

  In a rewritable optical disc such as a CD-RW (CD-rewritable), a DVD-RW (DVD-rewritable), and a DVD + RW (DVD + rewritable) including a special alloy on a recording surface, a special alloy is used when forming a mark area. After being heated to the first temperature, it is rapidly cooled to an amorphous state. On the other hand, when forming the space region, the special alloy is heated to a second temperature (<first temperature) and then gradually cooled to be in a crystalline state. As a result, the reflectance in the mark area is lower than that in the space area. In this case, in order to remove the influence of heat storage, the light emission power for forming the mark area is divided into a plurality of pulses (multi-pulse). Such a control method of the light emission power is also called a multi-pulse recording method. The maximum value of the multi-pulsed light emission power is also called peak power, and the minimum value is also called bottom power. The emission power when forming the space region is also called erase power (peak power> erase power> bottom power). With the increase in recording speed, a multi-pulse recording method has been proposed for DVD-type optical disks (DVD-R, DVD + R, etc.) even for dye-type disks.

  In the write-once type optical disk and the rewritable optical disk, the track is meandered (wobbled) at the time of manufacture, and information is added by modulating the meandering shape. For example, DVD + R and DVD + RW (hereinafter also referred to as “DVD + system” for convenience) use a phase modulation method.

  Therefore, for example, in an optical disk device compatible with a DVD + system, when accessing an optical disk, a wobble signal corresponding to a meandering shape is detected from a return light beam emitted from a light source and reflected on a track, and a reference clock signal is determined from the wobble signal. At the same time, the wobble signal is phase-demodulated in synchronization with the reference clock signal to obtain the information. In the DVD + system, particularly important information added to a track is information corresponding to address information. When recording user data, the optical disc device controls the recording position based on the address information and the reference clock signal.

  Therefore, if the address information cannot be correctly detected, the user data cannot be recorded in a predetermined area, and a recording error may occur. In particular, in a write-once DVD + R, if a recording error occurs, the optical disc cannot be reused. Therefore, it is very important to accurately detect a wobble signal.

  The wobble signal is detected based on the reflected light from the track. However, due to fluctuations in the recording data recorded on the optical disk or the output of the laser light, the reflected light has a complicated component that becomes noise with respect to the wobble signal. include. Therefore, for example, the reflected light from the track is received by a light receiving element (two-divided light receiving element) divided into two by a dividing line in a direction corresponding to the tangential direction of the track, and the output signal (photoelectric conversion signal) of each light receiving element Then, after performing predetermined level adjustments respectively, a device that generates a difference signal between the signals, that is, a push-pull signal, and detects a wobble signal has been proposed (for example, see Patent Documents 2 to 6). .

  By the way, the signal characteristics of the signal output from the light receiving element are greatly different between the case where the reflected light from the track contains the RF signal component and the case where the RF signal component is not contained. Therefore, in order to generate a push-pull signal having a low noise level both at the time of recording and at the time of reproduction, a circuit that generates a push-pull signal when reflected light from a track includes an RF signal component; A circuit that generates a push-pull signal when the reflected light from the track does not include an RF signal component is required, which has been one of the obstacles to miniaturization of the optical disk device.

JP 2001-35090 A JP 2001-266486 A JP-A-2002-117536 JP 2003-59056 A JP-A-2003-77130 JP-A-8-194969

The present invention has been made under such circumstances, and an object of the present invention is to provide an optical disk device that can stably perform recording and reproduction on an optical disk without increasing the size.

The invention according to claim 1 irradiates light onto a recording surface of an optical disc on which spiral or concentric tracks are formed, and records information by forming a mark area and a space area on the recording surface, An optical disc device that irradiates light onto a recording surface of an optical disc and reproduces information by detecting a mark area and a space area formed on the recording face, wherein at least the reflected light from the recording face of the optical disc, Receiving light at a first light receiving region and a second light receiving region divided by a dividing line in a direction corresponding to a tangential direction of a track, outputting a first photoelectric conversion signal from the first light receiving region, A photodetector that outputs a second photoelectric conversion signal from a second light receiving region; a first signal adjustment circuit that adjusts the first photoelectric conversion signal with a first gain; and the second photoelectric conversion signal The Mean levels and the respectively detected, their output signal amplitude and the first signal conditioning circuit during recording of the output signal of the first signal conditioning circuit; the second signal conditioning circuit and for adjusting in the gain One is selected as a first determination value, and the amplitude of the output signal of the second signal adjustment circuit and the average level of the output signal of the second signal adjustment circuit during recording are respectively detected, and Is selected as a second determination value, and the first gain and the second gain are selected so that the first determination value and the second determination value are equal to each other . a gain determining circuit for determining at least one; and a difference signal generation circuit for generating a difference signal between the output signal of the output signal and the second signal adjusting circuit of the first signal conditioning circuit; using said difference signal Record and reproduce information An optical disc apparatus provided with; management device and.

According to this, the reflected light from the recording surface of the optical disk on which the spiral or concentric tracks are formed, the light receiving surface of the optical disk is separated from the first light receiving region by the dividing line at least in the direction corresponding to the tangential direction of the track. The light is received by the photodetector divided into two light receiving areas. The first photoelectric conversion signal from the first light receiving region is adjusted by the first signal adjustment circuit with the first gain. On the other hand, the second photoelectric conversion signal from the second light receiving area is adjusted by the second signal adjustment circuit with the second gain. Then, the amplitude of the output signal of the first signal adjustment circuit and the average level of the output signal of the first signal adjustment circuit during recording are detected by the gain determination circuit. The gain determination circuit detects the amplitude of the output signal of the second signal adjustment circuit and the average level of the output signal of the second signal adjustment circuit during recording. Then, one of the amplitude and the average level of the output signal of the first signal adjustment circuit is selected as the first determination value by the gain determination circuit, and the amplitude and the average level of the output signal of the second signal adjustment circuit are selected. The one corresponding to the first determination value is selected as the second determination value, and the first gain and the second gain are set so that the first determination value and the second determination value are equal to each other . At least one is determined. As a result, a difference signal having a low noise level can be generated by the difference signal generation circuit with a simpler circuit configuration than in the related art. Then, based on the difference signal, for example, the position of the light spot formed on the recording surface can be controlled with high accuracy. Therefore, recording and reproduction with respect to the optical disk can be performed stably without increasing the size.

In this case, as the optical disk apparatus according to claim 2, wherein at least one of the first signal conditioning circuit and the second signal adjusting circuit may be to include a gain control amplifier circuit.

In each of the optical disk apparatuses according to the first and second aspects, as in the optical disk apparatus according to the third aspect, the gain determination circuit causes the first determination value to substantially match a preset target value. Then, the first gain may be determined.

In each of the optical disk devices according to the first to third aspects, as in the optical disk device according to the fourth aspect, the gain determination circuit causes the second determination value to substantially coincide with a preset target value. Then, the second gain can be determined.

In each of the optical disk devices according to the first to fourth aspects, as in the optical disk device according to the fifth aspect, the gain determination circuit determines an output signal of the first signal adjustment circuit according to a type of the optical disk. One of the amplitude and the average level is selected as the first judgment value, and one of the amplitude and the average level of the output signal of the second signal adjustment circuit corresponding to the first judgment value is the second judgment value. Can be selected as the judgment value of.

In this case, as in the optical disk device according to claim 6 , the optical disk is a rewritable optical disk, and the gain determination circuit determines an amplitude of an output signal of the first signal adjustment circuit as the first determination value. And the amplitude of the output signal of the second signal adjustment circuit is selected as the second determination value.

In this case, the optical disk may be an optical disk compliant with the DVD + RW standard, as in the optical disk device described in claim 7 .

In each of the optical disk devices according to the first to fourth aspects, when reproducing data from the optical disk as in the optical disk device according to the eighth aspect , the gain determining circuit outputs the output of the first signal adjusting circuit. The signal amplitude may be selected as the first determination value, and the amplitude of the output signal of the second signal adjustment circuit may be selected as the second determination value.

In each of the optical disk devices according to the fifth and eighth aspects, when data is recorded on the optical disk as in the optical disk device according to the ninth aspect , the gain determination circuit outputs the output of the first signal adjustment circuit. The average level of the signal may be selected as the first determination value, and the average level of the output signal of the second signal adjustment circuit may be selected as the second determination value.

In each of the optical disk devices according to the eighth and ninth aspects, as in the optical disk device according to the tenth aspect , the optical disk may be a write-once optical disk.

In this case, it is possible to be claimed as an optical disk apparatus according to claim 11, wherein the optical disc is an optical disc that conforms to the standard of DVD + R.

  Hereinafter, an embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows a schematic configuration of an optical disk device 20 according to an embodiment of the present invention.

  An optical disk device 20 shown in FIG. 1 includes a spindle motor 22, an optical pickup device 23, a laser control circuit 24, an encoder 25, a motor driver 27, a reproduction signal, for rotationally driving the optical disk 15 according to an embodiment of the present invention. It includes a processing circuit 28, a servo controller 33, a buffer RAM 34, a buffer manager 37, an interface 38, a flash memory 39, a CPU 40, a RAM 41, and the like. Note that the connection lines in FIG. 1 show typical flows of signals and information, and do not represent all of the connection relationships between the blocks. In the present embodiment, an information recording medium conforming to the DVD + R standard is used for the optical disc 15 as an example.

  The optical pickup device 23 is a device for irradiating the recording surface of the optical disk 15 with the spiral or concentric tracks formed thereon with laser light and receiving the reflected light from the recording surface. As shown in FIG. 2 as an example, the optical pickup device 23 includes a light source unit 51, a collimator lens 52, a beam splitter 54, an objective lens 60, a detection lens 58, a photodetector PD as a photodetector, and a driving system ( It includes a focusing actuator, a tracking actuator, a seek motor (all not shown), and the like.

  The light source unit 51 includes a semiconductor laser LD as a light source that emits laser light having a wavelength of 660 nm. In the present embodiment, the maximum intensity emission direction of the light beam of the laser light emitted from the light source unit 51 is defined as the + X direction.

  The collimator lens 52 is disposed on the + X side of the light source unit 51, and converts the light beam emitted from the light source unit 51 into substantially parallel light.

  The beam splitter 54 is disposed on the + X side of the collimator lens 52, and transmits the light beam substantially parallelized by the collimator lens 52 as it is. The beam splitter 54 splits a light beam (return light beam) reflected by the recording surface of the optical disk 15 and incident via the objective lens 60 in the −Z direction.

  The objective lens 60 is disposed on the + X side of the beam splitter 54, and focuses a light beam transmitted through the beam splitter 54 on a recording surface of the optical disc 15.

  The detection lens 58 is disposed on the −Z side of the beam splitter 54, and focuses the return light beam RB branched in the −Z direction by the beam splitter 54 on the light receiving surface of the light receiver PD.

  As shown in FIG. 3, the light receiving surface of the light receiving device PD is divided into two by a dividing line DL1 in a direction Dtan (vertical direction in FIG. 3) corresponding to a tangential direction of a track (shown by a dotted line). Further, it is divided into two by a dividing line DL2 in a direction Drad (left and right direction in FIG. 3) corresponding to a direction orthogonal to the tangential direction of the track. That is, the light receiving surface of the light receiver PD is divided into four light receiving areas (PDa, PDb, PDc, and PDd). The light receiving area PDa is located on the left side of the dividing line DL1 in FIG. 3 and on the upper side of the dividing line DL2 in FIG. The light receiving area PDb is located on the right side of the light receiving area PDa in FIG. The light receiving area PDc is located below the light receiving area PDb in FIG. The light receiving area PDd is located below the light receiving area PDa in FIG. Then, from each light receiving area, a signal corresponding to the amount of received light is output to the reproduction signal processing circuit 28. The light receiver PD is arranged so as to receive the return light beam RB almost at the center of the light receiving surface.

  The focusing actuator (not shown) is an actuator for slightly driving the objective lens 60 in a focus direction (here, the X-axis direction) which is the optical axis direction of the objective lens 60.

  The tracking actuator (not shown) is an actuator for minutely driving the objective lens 60 in a tracking direction (here, the Z-axis direction) which is a direction orthogonal to the tangential direction of the track.

  The seek motor (not shown) is a motor for driving the optical pickup device itself in the sledge direction (here, the Z-axis direction).

  Returning to FIG. 1, the flash memory 39 has a program area and a data area. In the program area, a program described by a code readable by the CPU 40 is stored. The data area stores information on the emission characteristics of the semiconductor laser LD, information on a seek operation of the optical pickup device 23 (hereinafter also referred to as “seek information”), recording conditions, and the like.

  The buffer RAM 34 includes a buffer area for temporarily storing data (recording data) to be recorded on the optical disk 15 and data (reproduced data) reproduced from the optical disk 15, and a variable area for storing various program variables. And

  The buffer manager 37 manages input and output of data to and from the buffer RAM 34. Then, when the amount of data accumulated in the buffer area reaches a predetermined amount, the CPU 40 is notified.

  The encoder 25 fetches the recording data stored in the buffer RAM 34 via the buffer manager 37 based on an instruction from the CPU 40, modulates data and adds an error correction code, and outputs a write signal to the optical disk 15. Generate. The write signal generated here is output to the laser control circuit 24.

  The laser control circuit 24 generates a drive signal for the semiconductor laser LD based on the light emission characteristics of the semiconductor laser LD, a write signal from the encoder 25, and the like. That is, the power of the laser light applied to the optical disk 15 is controlled.

  The interface 38 is a bidirectional communication interface with a host, and conforms to the ATAPI (AT Attachment Packet Interface) standard as an example.

  As shown in FIG. 4, the reproduction signal processing circuit 28 includes an I / V amplifier 28a, a servo signal detection circuit 28b, a wobble signal detection circuit 28c, an RF signal detection circuit 28d, and a decoder 28e.

  The I / V amplifier 28a converts a current signal, which is an output signal of the light receiver 59, into a voltage signal and amplifies the voltage signal with a predetermined gain. The converted voltage signal is output to the servo signal detection circuit 28b, the wobble signal detection circuit 28c, and the RF signal detection circuit 28d.

  The servo signal detection circuit 28b detects a servo signal (such as a focus error signal and a track error signal) based on the output signal of the I / V amplifier 28a. The servo signal detected here is output to the servo controller 33.

  The wobble signal detection circuit 28c detects the wobble signal Swb based on the output signal of the I / V amplifier 28a. As shown in FIG. 5 as an example, the wobble signal detection circuit 28c includes two addition circuits (c1, c10), two gain control amplifier circuits (GCA circuit: c2 (first signal adjustment circuit), and c11 ( Second signal adjustment circuit)), two amplitude detection circuits (c3, c12), two average level detection circuits (c4, c13), two changeover switches (c5, c14), and two comparison circuits (c6, c15). ), Two charge pumps (c7, c16), a D / A converter c8, two capacitors (c9, c17), and a subtraction circuit c18 (difference signal generation circuit).

  The adding circuit c1 generates a signal Sc1 obtained by adding the output signals Sb and Sc of the I / V amplifier 28a. Here, the signal Sb is an output signal of the I / V amplifier 28a corresponding to the output signal of the light receiving area PDb, and the signal Sc is the output signal of the I / V amplifier 28a corresponding to the output signal of the light receiving area PDc. That is, the signal Sc1 corresponding to the first photoelectric conversion signal is output from the addition circuit c1. The signal Sc1 from the adding circuit c1 is output to the gain control amplifier circuit c2.

  The gain control amplifier circuit c2 adjusts the output signal Sc1 of the addition circuit c1 with the first gain. The adjusted signal Sc2 is output to the subtraction circuit c18, the amplitude detection circuit c3, and the average level detection circuit c4. The first gain can be changed within a predetermined range (for example, -6 dB to +6 dB) by the first gain control voltage Vg1. Here, the first gain is set to increase as the first gain control voltage Vg1 increases, and the first gain is set to decrease as the first gain control voltage Vg1 decreases.

  The amplitude detection circuit c3 detects the amplitude of the output signal Sc2 of the gain control amplifier circuit c2. The detection result here is output to the changeover switch c5. Note that the amplitude detection circuit c3 can be configured to include, for example, a peak level detection circuit and a bottom level detection circuit.

  The average level detection circuit c4 detects the average level of the output signal Sc2 of the gain control amplifier circuit c2. The detection result here is output to the changeover switch c5. Note that the average level detection circuit c4 can be configured to include, for example, a low-pass filter.

  The changeover switch c5 selects one of the output signal of the amplitude detection circuit c3 and the output signal of the average level detection circuit c4 based on the selection signal Ssel from the CPU 40. Here, as an example, when the selection signal Ssel is 0 (low level), the output signal of the amplitude detection circuit c3 is selected, and when the selection signal Ssel is 1 (high level), the output signal of the average level detection circuit c4 is selected. It is set to be. The output signal of the changeover switch c5 becomes one input of the comparison circuit c6 as a first determination value.

  The D / A converter c8 converts the target voltage signal Stgt from the CPU 40 into an analog signal. The signal converted by the D / A converter c8 is output as a target value to the comparison circuits c6 and c15.

  The comparison circuit c6 compares the output signal of the changeover switch c5 with the output signal of the D / A converter c8. The comparison result is output to the charge pump c7.

  The charge pump c7 charges or discharges the capacitor c9 according to the comparison result of the comparison circuit c6. Here, the capacitor c9 is charged when the output signal of the changeover switch c5 is smaller than the output signal of the D / A converter c8, and when the output signal of the changeover switch c5 is larger than the output signal of the D / A converter c8. Is set to discharge the capacitor c9. The first gain control voltage Vg1 is set to increase when the capacitor c9 is charged, and to decrease when the capacitor c9 is discharged. That is, the output signal Sc2 of the gain control amplifier circuit c2 is controlled so that its amplitude or average level substantially matches the target value.

  The adding circuit c10 generates a signal obtained by adding the output signals Sa and Sd of the I / V amplifier 28a. Here, the signal Sa is an output signal of the I / V amplifier 28a corresponding to the output signal of the light receiving area PDa, and the signal Sd is an output signal of the I / V amplifier 28a corresponding to the output signal of the light receiving area PDd. That is, the signal Sc10 corresponding to the second photoelectric conversion signal is output from the addition circuit c10. The signal Sc10 from the adding circuit c10 is output to the gain control amplifier circuit c11.

  The gain control amplifier circuit c11 adjusts the output signal Sc10 of the adder circuit c10 with the second gain. The adjusted signal Sc11 is output to the subtraction circuit c18, the amplitude detection circuit c12, and the average level detection circuit c13. Note that the second gain can be changed within a predetermined range (for example, −6 dB to +6 dB) by the second gain control voltage Vg2. Here, the second gain is set to increase as the second gain control voltage Vg2 increases, and the second gain is set to decrease as the second gain control voltage Vg2 decreases.

  The amplitude detection circuit c12 detects the amplitude of the output signal Sc11 of the gain control amplifier circuit c11. The detection result here is output to the changeover switch c14. Note that the amplitude detection circuit c12 can be configured to include, for example, a peak level detection circuit and a bottom level detection circuit.

  The average level detection circuit c13 detects an average level of the output signal Sc11 of the gain control amplifier circuit c11. The detection result here is output to the changeover switch c14. Note that the average level detection circuit c13 can be configured to include, for example, a low-pass filter.

  The changeover switch c14 selects one of the output signal of the amplitude detection circuit c12 and the output signal of the average level detection circuit c13 based on the selection signal Ssel from the CPU 40. Here, as an example, when the selection signal Ssel is 0 (low level), the output signal of the amplitude detection circuit c12 is selected, and when the selection signal Ssel is 1 (high level), the output signal of the average level detection circuit c13 is selected. It is set to be. The output signal of the changeover switch c14 becomes one input signal of the comparison circuit c15 as a second determination value.

  The comparison circuit c15 compares the output signal of the changeover switch c14 with the output signal of the D / A converter c8. The comparison result is output to the charge pump c16.

  The charge pump c17 charges or discharges the capacitor c17 according to the comparison result of the comparison circuit c15. Here, the capacitor c17 is charged when the output signal of the changeover switch c14 is smaller than the output signal of the D / A converter c8, and when the output signal of the changeover switch c14 is larger than the output signal of the D / A converter c8. Is set to discharge the capacitor c17. Then, the second gain control voltage Vg2 is set to increase when the capacitor c17 is charged, and to decrease when the capacitor c17 is discharged. That is, the output signal Sc11 of the gain control amplifier circuit c11 is controlled so that its amplitude or average level substantially matches the target value.

  The subtraction circuit c18 subtracts the output signal Sc11 of the gain control amplifier circuit c11 from the output signal Sc2 of the gain control amplifier circuit c2 to generate a subtraction signal (push-pull signal). The subtraction signal generated here is output to the decoder 28e as a wobble signal Swb.

  The RF signal detection circuit 28d detects an RF signal based on an output signal of the I / V amplifier 28a.

  The decoder 28e demodulates the wobble signal Swb detected by the wobble signal detection circuit 28c to obtain address information and the like. The address information obtained here is output to the CPU 40. The decoder 28e performs a decoding process, an error detection process, and the like on the RF signal detected by the RF signal detection circuit 28d, performs an error correction process when an error is detected, and then outputs the data to the buffer manager 37 as reproduction data. Through the buffer RAM 34. The RF signal contains address information, and the address information extracted from the RF signal is output to the CPU 40.

  Returning to FIG. 1, the servo controller 33 generates a focus control signal for correcting a focus shift based on the focus error signal from the servo signal detection circuit 28b, and corrects the track shift based on the track error signal. To generate a tracking control signal. Each control signal generated here is output to the motor driver 27 when the servo is on, and is not output when the servo is off. Servo-on and servo-off are set by the CPU 40.

  The motor driver 27 outputs a driving signal of the focusing actuator to the optical pickup device 23 based on the focus control signal, and outputs a driving signal of the tracking actuator to the optical pickup device 23 based on the tracking control signal. That is, tracking control and focus control are performed by the servo signal detection circuit 28b, the servo controller 33, and the motor driver 27. The motor driver 27 outputs drive signals for the spindle motor 22 and the seek motor based on control signals from the CPU 40.

  The CPU 40 controls the operation of each section according to the program stored in the program area of the flash memory 39, and stores data necessary for the control in the variable area of the buffer RAM 34 and the RAM 41.

《Reproduction processing》
Next, processing (reproduction processing) in the optical disk device 20 when a reproduction request command is received from the host will be described with reference to FIG. The flowchart in FIG. 6 corresponds to a series of processing algorithms executed by the CPU 40. When a playback request command is received from the host, the start address of the program corresponding to the flowchart in FIG. Processing starts. Here, as an example, it is assumed that the first gain and the second gain are set so that the amplification factors are respectively approximately 1 (0 dB) as initial values.

  In the first step 401, a control signal for controlling the rotation of the spindle motor 22 based on the reproduction speed is output to the motor driver 27, and the reproduction signal processing circuit 28 is notified that a reproduction request command has been received from the host. .

  In the next step 403, 0 is set to the selection signal Ssel. Thus, the output signal of the amplitude detection circuit c3 is selected by the changeover switch c5 of the wobble signal detection circuit 28c. The output signal of the amplitude detection circuit c12 is selected by the changeover switch c14.

  In the next step 405, a value corresponding to the amplitude target voltage (Va) is set in the target voltage signal Stgt. Thereby, for example, when the amplitude of the output signal Sc1 of the adder circuit c1 is about ／ of the target voltage Va (see Sc1 in FIG. 7), the first gain becomes about 1.5 times and the gain control amplifier The amplitude of the output signal Sc2 of the circuit c2 substantially coincides with the target voltage Va (see Sc2 in FIG. 7). Further, for example, when the amplitude of the output signal Sc10 of the adder circuit c10 is about 1.5 times the target voltage Va (see Sc10 in FIG. 7), the second gain becomes about 2/3, and the gain control amplifier circuit The amplitude of the output signal Sc11 of c11 substantially coincides with the target voltage Va (see Sc11 in FIG. 7). Then, the output signal of the subtraction circuit c18, that is, the wobble signal Swb becomes a signal having almost twice the amplitude of the target voltage Va (see Swb in FIG. 7).

  In the next step 407, when it is confirmed that the rotation of the optical disk 15 has reached a predetermined linear velocity, the servo controller 33 is set to servo-on. Thus, tracking control and focus control are performed as described above. Note that the tracking control and the focus control are performed as needed until the reproduction process ends.

  In the next step 409, the current address is obtained based on the address information from the decoder 28e.

  In the next step 411, the difference (address difference) between the current address and the target address extracted from the reproduction request command is calculated.

  In the next step 413, it is determined whether a seek is necessary based on the address difference. Here, a threshold stored in the flash memory 39 is referred to as one of the seek information. If the address difference exceeds the threshold, the determination is affirmed and the process proceeds to step 415.

  In this step 415, a control signal of the seek motor according to the address difference is output to the motor driver 27. Then, the process returns to step 409.

  On the other hand, if it is determined in step 413 that the seek is not necessary, the determination is negative and the process proceeds to step 417.

  In this step 417, it is determined whether or not the current address matches the target address. If the current address does not match the target address, the determination here is denied, and the routine proceeds to step 419.

  In this step 419, the current address is obtained based on the address information from the decoder 28e. Then, the process returns to step 417.

  Hereinafter, the processing of steps 417 → 419 is repeatedly performed until the determination in step 417 is affirmed.

  If the current address matches the target address, the determination at step 417 is affirmative, and the routine goes to step 421.

  In this step 421, reading is instructed to the reproduction signal processing circuit 28. Thus, the reproduction data is obtained by the reproduction signal processing circuit 28 and stored in the buffer RAM 34. This reproduced data is transferred to the host via the buffer manager 37 and the interface 38 in sector units. When the reproduction of all data specified by the host is completed, a predetermined end process is performed, and then the reproduction process ends.

《Recording processing》
Further, processing (recording processing) in the optical disk device 20 when a recording request command is received from the host will be briefly described with reference to FIG. The flowchart of FIG. 8 corresponds to a series of processing algorithms executed by the CPU 40. When a recording request command is received from the host, the start address of the program corresponding to the flowchart of FIG. Processing starts. Here, as an example, it is assumed that the first gain and the second gain are set so that the amplification factors are respectively approximately 1 (0 dB) as initial values.

  In the first step 501, a control signal for controlling the rotation of the spindle motor 22 based on the recording speed is output to the motor driver 27, and the fact that the recording request command has been received from the host is notified to the reproduction signal processing circuit. . Further, it instructs the buffer manager 37 to store the data (recording data) received from the host in the buffer RAM 34.

  In the next step 503, 1 is set to the selection signal Ssel. Thus, the output signal of the average level detection circuit c4 is selected by the changeover switch c5 of the wobble signal detection circuit 28c. The output signal of the average level detection circuit c13 is selected by the changeover switch c14. Here, as shown in FIG. 9 as an example, the output signal of each gain control amplifier circuit has an impulse-like signal waveform (signal characteristic) having a large peak value corresponding to the write pulse. Is difficult to detect with high accuracy. Therefore, in this case, the average level is detected.

  In the next step 505, a value corresponding to the average level target voltage (referred to as Vb) is set in the target voltage signal Stgt. Thus, for example, when the average level (Vav1) of the output signal Sc1 of the addition circuit c1 is about 1.5 times the target voltage Vb (see Sc1 in FIG. 9), the first gain is about 2 / The average level (referred to as Vav12) of the output signal Sc2 of the gain control amplifier circuit c2 becomes substantially equal to the target voltage Vb (see Sc2 in FIG. 9). For example, when the average level (Vav10) of the output signal Sc10 of the addition circuit c10 is about ２ of the target voltage Vb (see Sc10 in FIG. 9), the second gain is about 1.5 times. The average level (referred to as Vav11) of the output signal Sc11 of the gain control amplifier circuit c11 substantially coincides with the target voltage Vb (see Sc11 in FIG. 9). Then, the output signal of the subtraction circuit c18, that is, the wobble signal Swb becomes a signal whose average level is almost 0 (see Swb in FIG. 9).

  In the next step 507, when it is confirmed that the rotation of the optical disk 15 has reached a predetermined linear velocity, the servo controller 33 is set to servo-on. Thus, tracking control and focus control are performed as described above. Note that the tracking control and the focus control are performed as needed until the recording process ends.

  In the next step 509, OPC (Optimum Power Control) is performed based on the recording speed to obtain an optimum recording power. That is, while changing the recording power stepwise, predetermined data is trial-written in the PCA area, and then those data are sequentially reproduced. For example, the value of asymmetry detected from the RF signal is obtained in advance by an experiment or the like. It is determined that the recording quality is the highest when the value substantially coincides with the target value, and the recording power at that time is set as the optimum recording power.

  In the next step 511, the current address is obtained based on the address information from the decoder 28e.

  In the next step 513, the difference (address difference) between the current address and the target address is calculated.

  In the next step 515, it is determined whether a seek is necessary based on the address difference. Here, a threshold stored in the flash memory 39 is referred to as one of the seek information. If the address difference exceeds the threshold, the determination is affirmed and the process proceeds to step 517.

  In step 517, a control signal of the seek motor according to the address difference is output to the motor driver 27. Thus, the seek motor is driven, and the seek operation is performed. Then, the process returns to step 511.

  If it is determined in step 515 that the address difference does not exceed the threshold value, the determination here is denied, and the process proceeds to step 519.

  In this step 519, it is determined whether or not the current address matches the target address. If the current address does not match the target address, the determination here is denied, and the routine proceeds to step 521.

  In this step 521, the current address is obtained based on the address information from the decoder 28e. Then, the process returns to step 519.

  Hereinafter, the processing of steps 519 to 521 is repeated until the determination in step 519 is affirmed.

  If the current address matches the target address, the determination at step 519 is affirmed, and the routine goes to step 523.

  In this step 523, writing is permitted to the encoder 25. As a result, the recording data is written to the optical disk 15 via the encoder 25, the laser control circuit 24, and the optical pickup device 23. When all the recording data has been written, a predetermined end process is performed, and then the recording process ends.

  As is clear from the above description, in the optical disk device 20 according to the present embodiment, a push-pull signal generation circuit is realized by the wobble signal detection circuit 28c. Then, two amplitude detection circuits (c3, c12), two average level detection circuits (c4, c13), two changeover switches (c5, c14), two comparison circuits (c6, c15), and two charge pumps ( c7, c16) and two capacitors (c9, c17) implement a gain determination circuit.

  In the optical disc device 20 according to the present embodiment, a processing device is realized by the optical pickup device 23, the CPU 40, and a program executed by the CPU 40. However, it goes without saying that the present invention is not limited to this. That is, the above embodiment is merely an example, and at least a part of the processing device realized by the processing according to the program by the CPU 40 may be configured by hardware, or may be entirely configured by hardware. good.

  As described above, in the optical disk device 20 according to the present embodiment, in the wobble signal detection circuit 28c, the photoelectric conversion signal from the light receiving region PDb (part of the first light receiving region) of the light receiving device PD and the light receiving region The photoelectric conversion signal from PDc (part of the first light receiving area) is added by the adding circuit c1. Then, the output signal (first photoelectric conversion signal) of the adding circuit c1 is adjusted by the first gain by the gain control amplifier circuit c2 (first signal adjusting circuit). On the other hand, the photoelectric conversion signal from the light receiving region PDa (part of the second light receiving region) of the light receiving device PD and the photoelectric conversion signal from the light receiving region PDd (part of the second light receiving region) are added by the addition circuit c10. You. The output signal (second photoelectric conversion signal) of the adding circuit c10 is adjusted by the second gain by the gain control amplifier circuit c11 (second signal adjusting circuit).

  In this case, for example, one of the amplitude and the average level of the output signal of the gain control amplifier circuit c2 is selected according to the signal characteristics of each photoelectric conversion signal to determine the first gain, and the gain control amplifier circuit c11 By selecting one of the amplitude and average level of the output signal and determining the second gain, the noise component included in the output signal (push-pull signal) of the subtraction circuit c18 (difference signal generation circuit) is efficiently reduced. It is possible to do. That is, a wobble signal with a low noise level can be generated with a simpler circuit configuration than in the related art. Therefore, it is possible to reduce the size of the wobble signal detection circuit while maintaining the noise included in the detected wobble signal at a low level.

  Further, according to the optical disk device 20 according to the present embodiment, the light reflected from the recording surface of the optical disk on which the spiral or concentric tracks are formed has four light receiving areas (PDa, PDb, PDc, PDd). ) Are received by the photodetector PD. Then, the wobble signal detection circuit 28c adds the photoelectric conversion signal from the light receiving area PDb (part of the first light receiving area) and the photoelectric conversion signal from the light receiving area PDc (part of the first light receiving area). (First photoelectric conversion signal), a photoelectric conversion signal from the light receiving area PDa (part of the second light receiving area), and a photoelectric conversion signal from the light receiving area PDd (part of the second light receiving area). Is generated, and a difference signal (push-pull signal) from the signal (the second photoelectric conversion signal) to which is added is generated. Thus, even if there is an eccentricity of the optical disk 15 or an assembly error of the pickup device 23, a noise component included in the wobble signal output from the wobble signal detection circuit 28c can be efficiently reduced. Therefore, the position of the light spot formed on the recording surface can be controlled with high precision, and as a result, recording and reproduction on the optical disk 15 can be performed stably without increasing the size.

  In the wobble signal detection circuit 28c, during reproduction, the first gain is determined so that the amplitude of the output signal of the gain control amplifier circuit c2 substantially matches the target value of the amplitude, and the gain control amplifier circuit c11 The second gain is determined so that the amplitude of the output signal of FIG. During recording, the first gain is determined so that the average level of the output signal of the gain control amplifier circuit c2 substantially matches the target value of the average level, and the average of the output signal of the gain control amplifier circuit c11 is determined. The second gain is determined such that the level substantially matches the target value of the average level. Accordingly, even when the signal characteristics of the photoelectric conversion signal from the photodetector PD are significantly different between the time of recording and the time of reproduction, it is possible to stably acquire an accurate wobble signal.

  In the above embodiment, the case where the optical disk 15 complies with the DVD + R standard has been described. However, the present invention is not limited to this, and any optical disk having a meandering track may be used. For example, it may be a DVD + RW which is a rewritable optical disk. In this case, in the recording process, it is better to set the selection signal Ssel to 0 and set the target voltage signal Stgt to a value corresponding to the amplitude target voltage, as in the reproduction process, to obtain better results. ing.

  In the above embodiment, the case where the gain control amplifier circuit is used as the first signal adjustment circuit has been described, but the present invention is not limited to this.

  In the above embodiment, the case where the gain control amplifier circuit is used as the second signal adjustment circuit has been described, but the present invention is not limited to this.

  In the above embodiment, the case where the CPU 40 outputs the selection signal Ssel and the target voltage signal Stgt to the wobble signal detection circuit 28c has been described. However, the present invention is not limited to this. For example, as shown in FIG. The signal detection circuit 28c may include a target value selection circuit c19 that selects one of the target value of the amplitude and the target value of the average level in accordance with the selection signal Ssel and outputs the selected value to each comparison circuit. In this case, the target voltage signal Stgt becomes unnecessary.

  Further, in the above embodiment, the case where the gain of each of the gain control amplifier circuits is adjusted by using the charge and discharge of the capacitor has been described.However, the present invention is not limited to this. When the determined gain control amplifier circuit is used, a circuit for changing the set value of the register in accordance with the comparison result of each of the comparison circuits may be provided. In this case, the charge pumps and the capacitors are not required.

  Further, in the above embodiment, the case where the comparison circuit is arranged after the changeover switch has been described. However, the present invention is not limited to this. For example, the amplitude detected at the stage after the amplitude detection circuit and the target value of the amplitude A comparison circuit for comparison is arranged, and a comparison circuit for comparing the detected average level with a target value of the average level is arranged at a stage subsequent to the average level detection circuit, and one of output signals of each comparison circuit is switched by a changeover switch. You may make it select.

  In the above embodiment, at least one of the first gain and the second gain may be determined so that the output signals of the changeover switches become substantially equal. FIG. 11 shows a wobble signal detection circuit when only the second gain is determined as an example. In this case, the output signal of the changeover switch c5 and the output signal of the changeover switch c14 become the input signals of the comparison circuit c15. The comparison circuit c15 compares the output signal of the changeover switch c5 with the output signal of the changeover switch c14, and outputs the comparison result to the charge pump c16. Then, the charge pump c16 charges or discharges the capacitor c17 according to the comparison result of the comparison circuit c15 as in the above-described embodiment. As a result, the output signal Sc11 of the gain control amplifier circuit c11 is controlled so that its amplitude or average level substantially matches the amplitude or average level of the output signal Sc2 of the gain control amplifier circuit c2. This eliminates the need for the comparison circuit c6, the charge pump c7, and the capacitor c9 in the above-described embodiment, and makes it possible to further reduce the size and cost.

  Further, in the above-described embodiment, the case where the optical pickup device 23 includes one semiconductor laser has been described. However, the present invention is not limited thereto. For example, a plurality of semiconductor lasers that emit light beams having different wavelengths may be provided. In this case, for example, it may include at least one of a semiconductor laser emitting a light beam having a wavelength of about 405 nm, a semiconductor laser emitting a light beam having a wavelength of about 660 nm, and a semiconductor laser emitting a light beam having a wavelength of about 780 nm. . That is, the optical disk device may be an optical disk device that supports a plurality of types of optical disks conforming to different standards.

  In the above embodiment, the case where the interface 38 conforms to the ATAPI standard has been described. However, the present invention is not limited to this. For example, ATA (AT Attachment), SCSI (Small Computer System Interface), USB (Universal Serial Bus) 1 2.0, USB 2.0, IEEE 1394, IEEE 802.3, serial ATA, and serial ATAPI.

FIG. 1 is a block diagram illustrating a configuration of an optical disc device according to an embodiment of the present invention. FIG. 2 is a diagram illustrating a configuration of an optical pickup device in FIG. 1. FIG. 3 is a diagram for explaining the light receiver of FIG. 2. FIG. 2 is a block diagram illustrating a configuration of a reproduction signal processing circuit in FIG. 1. FIG. 5 is a block diagram for describing a configuration of a wobble signal detection circuit in FIG. FIG. 11 is a flowchart for describing a reproduction process in the optical disk device performed in response to a reproduction request command from a host. FIG. 5 is a waveform chart for explaining the operation of the wobble signal detection circuit of FIG. 4 in a reproduction process. 9 is a flowchart for describing a recording process in the optical disc device performed in response to a recording request command from a host. FIG. 5 is a waveform chart for explaining the operation of the wobble signal detection circuit of FIG. 4 in a recording process. FIG. 5 is a block diagram for explaining another configuration example (part 1) of the wobble signal detection circuit in FIG. 4. FIG. 11 is a block diagram for describing another configuration example (part 2) of the wobble signal detection circuit in FIG. 4.

Explanation of reference numerals

15 optical disk, 20 optical disk device, 23 optical pickup device (part of processing device), 28c wobble signal detection circuit (push-pull signal generation circuit), 40 CPU (part of processing device), c2 gain Control amplifier circuit (first signal adjustment circuit), c3, c12... Amplitude detection circuit (part of gain determination circuit), c4, c13... Average level detection circuit (part of gain determination circuit), c5, c14. Switches (part of the gain determination circuit), c6, c15... Comparison circuits (part of the gain determination circuit), c7, c16... Charge pumps (part of the gain determination circuit), c9, c17. C11: gain control amplifier circuit (second signal adjustment circuit), c18: subtraction circuit (difference signal generation circuit), PD: photodetector (photodetector)

Claims (11)

The recording surface of the optical disk on which the spiral or concentric tracks are formed is irradiated with light, information is recorded by forming a mark area and a space area on the recording surface, and the recording surface of the optical disk is irradiated with light. An optical disc device for reproducing information by detecting a mark area and a space area formed on the recording surface,
The first light receiving area receives the reflected light from the recording surface of the optical disk at least in a first light receiving area and a second light receiving area divided into two by a dividing line in a direction corresponding to a tangential direction of the track. And a photodetector that outputs a first photoelectric conversion signal from the second light receiving area and outputs a second photoelectric conversion signal from the second light receiving region;
A first signal adjustment circuit that adjusts the first photoelectric conversion signal with a first gain;
A second signal adjustment circuit that adjusts the second photoelectric conversion signal with a second gain;
Detecting the amplitude of the output signal of the first signal adjustment circuit and the average level of the output signal of the first signal adjustment circuit during recording, and selecting one of them as a first determination value; The amplitude of the output signal of the second signal adjustment circuit and the average level of the output signal of the second signal adjustment circuit during recording are respectively detected, and one corresponding to the first determination value is determined as a second determination value. A gain determining circuit that determines at least one of the first gain and the second gain so that the first determination value and the second determination value are equal to each other ;
A difference signal generation circuit that generates a difference signal between the output signal of the first signal adjustment circuit and the output signal of the second signal adjustment circuit;
An optical disc device comprising: a processing device that records and reproduces information by using the difference signal. The optical disk device according to claim 1, wherein at least one of the first signal adjustment circuit and the second signal adjustment circuit includes a gain control amplifier circuit . 3. The optical disc apparatus according to claim 1, wherein the gain determination circuit determines the first gain such that the first determination value substantially matches a preset target value. . 4. The gain determination circuit according to claim 1, wherein the gain determination circuit determines the second gain such that the second determination value substantially matches a preset target value. An optical disc device according to claim 1. The gain determination circuit selects one of an amplitude and an average level of an output signal of the first signal adjustment circuit as the first determination value in accordance with a type of the optical disc, and the second signal adjustment circuit 5. The optical disk according to claim 1 , wherein one of an amplitude and an average level of the output signal corresponding to the first determination value is selected as the second determination value. 6. apparatus. The optical disk is a rewritable optical disk,
The gain determination circuit selects the amplitude of the output signal of the first signal adjustment circuit as the first determination value, and uses the amplitude of the output signal of the second signal adjustment circuit as the second determination value. 6. The optical disk device according to claim 5 , wherein the optical disk device is selected. The optical disk device according to claim 6 , wherein the optical disk is an optical disk compliant with the DVD + RW standard. When reproducing data from the optical disc, the gain determination circuit selects the amplitude of the output signal of the first signal adjustment circuit as the first determination value, and outputs the output signal of the second signal adjustment circuit. The optical disk device according to any one of claims 1 to 4 , wherein an amplitude of the optical disc is selected as the second determination value. When recording data on the optical disc, the gain determination circuit selects an average level of an output signal of the first signal adjustment circuit as the first determination value, and outputs the average level of the output signal of the second signal adjustment circuit. the optical disk apparatus according to claim 5 or 8, wherein the selecting the average level signal as the second judgment value. The optical disk apparatus according to claim 8 or 9 wherein the optical disc is characterized in that it is a write-once optical disc. The optical disk device according to claim 10 , wherein the optical disk is an optical disk compliant with the DVD + R standard.

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