WO2005041178A1 - トラッキング制御装置および方法、フォーカス制御装置および方法、並びに信号処理装置 - Google Patents
トラッキング制御装置および方法、フォーカス制御装置および方法、並びに信号処理装置 Download PDFInfo
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- WO2005041178A1 WO2005041178A1 PCT/JP2004/015729 JP2004015729W WO2005041178A1 WO 2005041178 A1 WO2005041178 A1 WO 2005041178A1 JP 2004015729 W JP2004015729 W JP 2004015729W WO 2005041178 A1 WO2005041178 A1 WO 2005041178A1
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
- G11B7/08—Disposition or mounting of heads or light sources relatively to record carriers
- G11B7/09—Disposition or mounting of heads or light sources relatively to record carriers with provision for moving the light beam or focus plane for the purpose of maintaining alignment of the light beam relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
- G11B7/08—Disposition or mounting of heads or light sources relatively to record carriers
- G11B7/09—Disposition or mounting of heads or light sources relatively to record carriers with provision for moving the light beam or focus plane for the purpose of maintaining alignment of the light beam relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following
- G11B7/0901—Disposition or mounting of heads or light sources relatively to record carriers with provision for moving the light beam or focus plane for the purpose of maintaining alignment of the light beam relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following for track following only
- G11B7/0906—Differential phase difference systems
Definitions
- the present invention relates to a tracking control device and method capable of improving the accuracy of tracking control, a focus control device and method capable of improving the accuracy of focus control, and a signal processing device.
- DVD media includes DVD-RAM, which can be overwritten multiple times, DVD-R, which can record but cannot overwrite, and DVD-ROM, which can be used only for playback.
- DVD-RAM which can be overwritten multiple times
- DVD-R which can record but cannot overwrite
- DVD-ROM which can be used only for playback.
- the physical standards are different from each other. Therefore, the optimal method for detecting a tracking error differs for each DVD medium.
- the phase difference method is a method for detecting a tracking error by using a change in the amount of light due to pits or recording marks on an optical disc. For example, when reproducing a DVD-ROM or DVD-R, a tracking error is often detected using the phase difference method.
- the push-pull method is a method for detecting a tracking error by using a change in the amount of light due to a guide groove of an optical disc. For example, when recording / reproducing a DVD-RAM or recording a DVD-R, a tracking error is often detected using the push-pull method.
- FIG. 3 shows a configuration of a circuit that detects a tracking error using the phase difference method.
- Light reception amount detection section 301 receives light reflected from an optical disc.
- the light reception amount detection unit 301 is divided into four regions A, B, C, and D by a boundary line along a tangential direction of a recording track of the optical disc and a boundary line along a direction perpendicular to the boundary line.
- Each of the four regions A, B, C, and D is configured to generate a light reception amount signal corresponding to the light reception amount and output the signal.
- Adder 302 adds the received light amount signal output from area A of received light amount detection section 301 and the received light amount signal output from area C of received light amount detection section 301.
- the regions A and C are regions that are arranged diagonally in the received light amount detection unit 301.
- Adder 303 adds the received light amount signal output from region B of received light amount detection unit 301 and the received light amount signal output from region D of received light amount detection unit 301.
- the regions B and D are regions that are arranged diagonally in the received light amount detection unit 301.
- Phase comparator 304 detects a phase difference between a signal output from adder 302 and a signal output from adder 303, and generates a tracking error signal according to the phase difference.
- FIG. 4 shows a configuration of a circuit for detecting a tracking error using the push-pull method.
- the received light amount detection unit 401 has the same configuration as the received light amount detection unit 301 shown in FIG. That is, the received light amount detection unit 401 receives the reflected light of the optical disk power.
- the received light amount detection unit 401 is divided into four areas A, B, C, and D by a boundary line along the tangential direction of the recording track of the optical disc and a boundary line along the direction perpendicular thereto. .
- Each of the four regions A, B, C, and D is configured to generate a light reception amount signal corresponding to the light reception amount and output the signal.
- Adder 402 adds the received light amount signal output from region A of received light amount detection unit 401 and the received light amount signal output from region B of received light amount detection unit 401.
- Areas A and B are areas on the same side of the boundary line along the tangential direction of the recording track.
- Adder 403 adds the received light amount signal output from area D of received light amount detecting section 401 to the received light amount signal that also outputs area C force of received light amount detecting section 401.
- Areas C and D are areas on the same side of the boundary line along the tangential direction of the recording track.
- Subtractor 404 generates a tracking error signal by subtracting the signal output from adder 403 from the signal output from adder 402.
- the circuit is a circuit that can respond to a high frequency band.
- the circuit is a circuit capable of responding to a high frequency band of several MHz to several tens of MHz.
- Patent Document 1 JP-A-2002-109759 (page 9)
- Patent Document 2 JP-A-5-325233 (pages 2-4)
- the response frequency of the light reception amount detection unit is high.
- the laser power is usually modulated. High-frequency components of several tens of MHz to several hundreds of MHz, such as the modulation component of the laser power, are superimposed on the tracking error signal.
- the circuit for detecting a focus error also requires an RF signal system and a force error detection system to reduce the size and cost of the optical head.
- the received light amount detection unit is shared.
- the response frequency of the received light amount detecting section is high. For this reason, a high-frequency component of several tens to several hundred MHz, such as a modulation component of laser power, is superimposed on the focus error signal.
- the tracking error signal and the focus error signal pass through a low-pass filter called an anti-aliasing filter for digital control. Therefore, the high frequency components of the tracking error signal and the focus error signal have been removed by the anti-aliasing filter. Therefore, even if the above-mentioned high-frequency component is superimposed on the tracking error signal or the focus error signal, there is no problem.
- the present invention provides a tracking control device and method capable of improving the accuracy of tracking control, a focus control device and method capable of improving the accuracy of focus control, and a signal processing device.
- the purpose is to do.
- the tracking control device of the present invention converges a light beam on a recording surface of the optical disk to form a light beam spot on the recording surface of the optical disk, and records the light beam spot on the recording surface of the optical disk.
- Each of the plurality of low-pass filters is provided with a frequency equal to or higher than a predetermined cutoff frequency from a corresponding one of the plurality of received light signals output from the light detection means.
- a filter unit that removes a component having the following formula: a predetermined operation is performed on a plurality of signals output from the filter unit to obtain a light beam spot and a track to be scanned on a recording surface of the optical disc.
- a tracking error detection unit that generates a tracking error signal indicating a deviation amount between the optical disk and the moving unit so that the light beam spot follows a track on a recording surface of the optical disc in response to the tracking error signal.
- a tracking control unit that performs the above-mentioned operations, thereby achieving the above object.
- the apparatus may further include a band control unit that controls the filter unit such that the predetermined cutoff frequency decreases as a recording speed for recording information on the optical disk increases.
- the filter unit further includes a plurality of equalizers, and each of the plurality of equalizers is included in a corresponding one of the plurality of received light amount signals output from the light detection unit.
- Amplifying a component of a predetermined frequency band to be applied the optical disc device performs a signal output from the low-pass filter and a signal output from the equalizer.
- a switching unit that selectively outputs one of the switching units, the switching unit may provide a signal output from the switching unit to the tracking error detection unit as a signal output from the filter unit. Good.
- the switching unit When the optical disc device is in a recording operation state for a recordable optical disc, the switching unit provides a signal output from the low-pass filter to the tracking error detection unit, When the device is in a reproducing operation state for a read-only optical disk, the signal output from the equalizer force may be provided to the tracking error detection unit.
- the focus control device of the present invention includes a converging means for forming a light beam spot on the recording surface of the optical disc by converging the light beam on the recording surface of the optical disc; Moving means for moving in a direction substantially perpendicular to the surface; and a light detecting means having a light receiving surface for detecting light reflected from the optical disk, wherein the light receiving surface is divided into a plurality of regions.
- each of the plurality of low-pass filters includes a corresponding one of a plurality of received light amount signals output from the light detection means and a predetermined cutoff frequency.
- a focus error detection unit that generates a focus error signal indicating a shift amount; and a focus control unit that drives the moving unit so that the light beam spot follows a recording surface of the optical disc in accordance with the focus error signal.
- the apparatus may further include a band control unit that controls the filter unit such that the predetermined cutoff frequency decreases as a recording speed for recording information on the optical disk increases.
- the tracking control method of the present invention is a tracking control method for performing tracking control using a tracking control device, wherein the focus control device emits a light beam.
- Converging means for forming a light beam spot on the recording surface of the optical disc by converging the light beam on the recording surface of the optical disc; moving means for moving the light beam spot in a radial direction of the recording surface of the optical disc;
- Light receiving means having a light receiving surface for detecting light reflected from the light receiving device, wherein the light receiving surface is divided into a plurality of regions, and each of the plurality of regions generates a light reception amount signal corresponding to a light reception amount;
- a light detecting means configured to output the received light amount signal, wherein the tracking control method outputs the light from the light detecting means using a filter unit including a plurality of low-pass filters.
- the method may further include controlling the filter unit such that the predetermined cutoff frequency decreases as the recording speed of recording information on the optical disc increases.
- the method may further include a step of selectively outputting one of a signal output from the pass filter and a signal output from the equalizer as a signal output from the filter unit.
- a signal output from the low-pass filter is output as a signal output from the filter unit, and the optical disk device is When a reproducing operation is being performed on a read-only optical disk, a signal output from the equalizer may be output as a signal output from the filter unit.
- the focus control method of the present invention implements focus control using a focus control device.
- a focus control method wherein the focus control device converges a light beam on a recording surface of an optical disc to form a light beam spot on a recording surface of the optical disc; Moving means for moving the spot in a direction substantially perpendicular to the recording surface of the optical disk; and light detecting means having a light receiving surface for detecting light reflected from the optical disk, wherein the light receiving surface has a plurality of light receiving surfaces.
- each of the plurality of regions includes a light detection unit configured to generate a light reception amount signal in accordance with a light reception amount and to output the light reception amount signal.
- the method includes using a filter unit including a plurality of low-pass filters to obtain a predetermined cut-off frequency or higher from each of the plurality of received light amount signals output from the light detection unit.
- the step of removing a component having a frequency and performing a predetermined operation on a plurality of signals output from the filter unit indicate an amount of deviation between the light beam spot and the recording surface of the optical disc.
- the method may further include controlling the filter unit such that the predetermined cutoff frequency decreases as the recording speed of recording information on the optical disc increases.
- the signal processing device of the present invention is a signal processing device used in a tracking control device, wherein the tracking control device converges a light beam on a recording surface of the optical disc to record on the optical disc.
- Converging means for forming a light beam spot on a surface moving means for moving the light beam spot in a radial direction of a recording surface of the optical disk, and light detecting means having a light receiving surface for detecting reflected light from the optical disk.
- the light receiving surface is divided into a plurality of regions, and each of the plurality of regions is configured to generate a received light amount signal according to a received light amount and output the received light amount signal.
- the signal processing device is a filter unit including a plurality of low-pass filters, wherein each of the plurality of low-pass filters is To remove components having a corresponding one of the received light quantity signal from the predetermined shielding sectional frequency or frequencies of the plurality of received light quantity signal output from the optical detection unit, a filter unit, from the filter unit By performing a predetermined operation on a plurality of output signals, a tracking error that generates a tracking error signal indicating a shift amount between the light beam spot and a track to be scanned on the recording surface of the optical disc is generated.
- a detection unit; and a tracking control unit that drives the moving unit so that the light beam spot follows a track on the recording surface of the optical disk in response to the tracking error signal, whereby the object is achieved. Is done.
- the apparatus may further include a band control unit that controls the filter unit such that the predetermined cutoff frequency decreases as a recording speed for recording information on the optical disc increases.
- the filter unit further includes a plurality of equalizers, and each of the plurality of equalizers is included in a corresponding one of the plurality of received light amount signals output from the light detection unit.
- the optical disk device further includes a switching unit that selectively outputs one of a signal output from the low-pass filter and a signal output from the equalizer. The switching unit may provide a signal output from the switching unit to the tracking error detection unit as a signal output from the filter unit.
- the switching section When the optical disc apparatus is in a recording operation state for a recordable optical disc, the switching section provides a signal output from the low-pass filter to the tracking error detection section, When the device is in a reproducing operation state for a read-only optical disk, the signal output from the equalizer force may be provided to the tracking error detection unit.
- the signal processing device of the present invention is a signal processing device used in a focus control device, wherein the focus control device converges a light beam on a recording surface of the optical disc to form a light beam on the recording surface of the optical disc.
- Light receiving means wherein the light receiving surface is divided into a plurality of regions, and each of the plurality of regions generates a light receiving amount signal according to a light receiving amount and outputs the light receiving amount signal.
- the signal processing device is a filter unit including a plurality of low-pass filters, wherein each of the plurality of low-pass filters is A filter unit for removing a component having a frequency equal to or higher than a predetermined cut-off frequency corresponding to one of the plurality of received light amount signals output, and a plurality of signals output from the filter unit.
- a focus error detection unit that generates a focus error signal indicating a shift amount between the optical beam spot and the recording surface of the optical disc; and the light source according to the focus error signal.
- a focus control unit that drives the moving unit so that the beam spot follows the recording surface of the optical disc, thereby achieving the above object.
- the optical disc may further include a band control unit that controls the filter unit so that the predetermined cutoff frequency decreases as the recording speed of recording information on the optical disc increases.
- a filter unit that removes unnecessary components while leaving components necessary for tracking control or focus control is provided immediately after the received light amount detection unit.
- the optical disc device according to the present invention is useful as a DVD multi-recorder, a DVD multi-drive, and the like. Further, the present invention can be applied not only to DVDs but also to any optical disk device that records and reproduces a plurality of media.
- FIG. 1 is a diagram showing a configuration of an optical disc device according to Embodiment 1 of the present invention.
- FIG. 2 is a diagram showing a configuration of an optical disc device according to Embodiment 2 of the present invention.
- FIG. 3 is a diagram showing a configuration of a circuit for detecting a tracking error using a phase difference method.
- FIG. 4 is a diagram showing a configuration of a circuit for detecting a tracking error using a push-pull method. Explanation of reference numerals
- FIG. 1 shows a configuration of an optical disk device according to Embodiment 1 of the present invention.
- the laser diode 2 emits laser light.
- the collimator lens 3 converts the laser light emitted from the laser diode 2 into parallel light.
- the beam splitter 4 allows the parallel light from the collimator lens 3 to pass through the objective lens 5 and also transmits the parallel light (reflected light from the optical disc 1) from the objective lens 5 in the direction in which the received light amount detection unit 6 is located.
- the objective lens 5 forms a light beam spot on the recording surface of the optical disc 1 by converging the parallel light passing through the collimating lens 3 and the beam splitter 4 on the recording surface of the optical disc 1.
- the objective lens 5 converts the reflected light from the optical disc 1 into parallel light, and passes the parallel light through the beam splitter 4.
- the lens drive unit 101 moves the light beam spot formed by the objective lens 5 in the radial direction of the recording surface of the optical disk 1.
- the received light amount detection unit 6 has a light receiving surface for detecting the reflected light from the optical disc 1.
- the light receiving surface is divided into four regions by a boundary line along the tangential direction of a track on the recording surface of the optical disk 1 and a boundary line along a direction perpendicular to the boundary line. Each of the four regions is configured to generate and output a received light amount signal according to the received light amount
- Filter section 106 has four sets of low-pass filters (LPF) and equalizers (EQ). Each LPF removes a component having a frequency equal to or higher than a predetermined cutoff frequency from one corresponding received light amount signal among the four received light amount signals output from the four regions of the received light amount detection unit 6, and the other components. Through. Each EQ amplifies and passes a component of a predetermined frequency band included in a corresponding one of the four received light amount signals output from the four regions of the received light amount detection unit 6, and outputs the other signals. Is removed. In addition, each LPF can switch the cutoff frequency according to the signal output from the band control unit 107. It is configured as follows.
- the disc discriminating unit 108 discriminates the type of the optical disc 1 loaded in the optical disc device based on the four received light amount signals from which the four received light amounts of the received light amount detecting unit 6 are also output.
- the physical standard of the optical disc 1 is different.
- the difference in the physical standard includes, for example, the reflectance of the optical disc 1 and the depth of the guide groove of the recording track. Due to this difference, the correlation between the amplitudes and phases of the four light reception amount signals output from the light reception amount detection unit 6 differs depending on the type of the optical disc 1.
- the disc discriminating unit 108 discriminates the type of the optical disc 1 by detecting this difference.
- the disc discriminating unit 108 may discriminate the type of the optical disc 1 according to signals other than the four received light quantity signals output from the received light quantity detecting unit 6. For example, when the optical disk 1 is housed in a cartridge having a shape unique to DVD-RAM, the disk discriminating section 108 outputs the optical disk 1 in accordance with an output signal from a sensor for detecting the shape of the cartridge. May be determined to be DVD-RAM!
- the management unit 109 stores information indicating the type of the optical disk 1 determined by the disk determination unit 108. Also, the management unit 109 stores information indicating whether the optical disk device is in a recording operation state or a reproduction operation state, and stores information indicating a recording speed and information indicating a reproduction speed.
- the switching control unit 103 switches according to the information indicating the type of the optical disc 1 stored by the management unit 109 and the information indicating whether the optical disc apparatus is in the recording operation state or the reproduction operation state.
- the signal is output to the unit 105 and the tracking error detection unit 104.
- the band control unit 107 generates a signal for switching the cutoff frequency of each LPF of the filter unit 106 according to the information indicating the recording speed stored by the management unit 109, and sends the signal to the filter unit 106. Output. Specifically, the band control unit 107 controls the filter unit 106 such that the cutoff frequency of each LPF decreases as the recording speed increases, and the cutoff frequency of each LPF increases as the recording speed decreases.
- Table 1 shows the recording speed (double speed at the time of recording), recording power (power of laser light at the time of recording), cutoff frequency (cutoff frequency of each LPF) when the optical disc 1 is a DVD-RAM.
- An example of the relationship is shown below.
- Table 2 shows an example of the relationship between recording speed (double speed during recording), recording power (power of laser light during recording), and cutoff frequency (cutoff frequency of each LPF) when optical disc 1 is DVD-R. Is shown.
- the recording speed for example, the speed at the time of recording
- the disturbance due to the modulation component of the laser power also increases.
- the recording power is originally large and the influence of the disturbance due to the modulation component of the laser power (recording power) is large. Therefore, the cutoff frequency of the LPF is controlled as in the present invention. That is very useful.
- the switching unit 105 has four 2-input / 1-output selectors. One of the two inputs a and b of each selector is connected to the output of the selector. The input a of each selector is connected to the output of the LPF, and the input b of each selector is connected to the output of the EQ.
- the LPF and EQ connected to the inputs a and b of each selector are a set of LPF and EQ to which the same received light amount signal is input in the filter unit 106.
- the switching unit 105 simultaneously switches the input of each selector to a or b according to the signal output from the switching control unit 103.
- the tracking error detection unit 104 determines the amount of deviation between the light beam spot and the track to be scanned on the recording surface of the optical disc 1 based on the four signals output from the switching unit 105. A tracking error signal is generated and output.
- Tracking error detection section 104 includes an arithmetic circuit (not shown) corresponding to the phase difference method and an arithmetic circuit (not shown) corresponding to the push-pull method.
- One of the two arithmetic circuits is selectively used according to the signal output from the switching control unit 103.
- An arithmetic circuit corresponding to the phase difference method includes an adder 302, an adder 303, and a phase comparator 304 shown in FIG.
- this arithmetic circuit instead of the four received light amount signals output from the received light amount detection unit 301 shown in FIG. 3, four signals output from the switching unit 105 are input to the SCALO calculators 302 and 303. Is done.
- An arithmetic circuit corresponding to the push-pull method includes an adder 402, an adder 403, and a subtractor 404 shown in FIG.
- this arithmetic circuit instead of the four received light amount signals output from the received light amount detection unit 401 shown in FIG. 4, four signals output from the switching unit 105 are input to the SCALO calculators 402 and 403. Is done.
- the control signal generation unit 102 performs tracking control for causing the light beam spot formed by the objective lens 5 to follow a track on the recording surface of the optical disc 1 in accordance with the tracking error signal output from the tracking error detection unit 104 Output a signal.
- the lens driving unit 101 moves the object in the radial direction of the optical disc 1 so that the light beam spot follows the track on the recording surface of the optical disc 1 according to the tracking control signal output from the control signal generating unit 102. Move lens 5.
- the optical disk device shown in FIG. 1 functions as a tracking control device that performs tracking control.
- the objective lens 5 functions as a converging means for forming a light beam spot on the recording surface of the optical disc 1 by converging the light beam on the recording surface of the optical disc 1.
- the convergence means is not limited to the objective lens 5. Any one or more elements can be used as convergence means as long as they have a function equivalent to the function of the convergence means described above.
- the lens driving unit 101 functions as a moving unit that moves the light beam spot formed by the objective lens 5 in the radial direction of the recording surface of the optical disk 1.
- the moving means is not limited to the lens driving unit 101. Any one or more elements can be used as the moving means as long as they have a function equivalent to the function of the moving means described above.
- the received light amount detection section 6 functions as a light detection means having a light receiving surface for detecting the reflected light from the optical disc 1.
- the light receiving surface is divided into a plurality of regions. Each of the plurality of regions is configured to generate a light reception amount signal corresponding to the light reception amount and output the signal.
- the light detecting means is not limited to the received light amount detecting section 6. As long as it has a function equivalent to the function of the light detection means described above, any one or more elements can be used as the light detection means.
- filter section 106 includes a plurality of equalizers (EQs).
- the filter unit 106 includes a plurality of low-pass filters (LPFs), each of the plurality of LPFs having a predetermined cutoff frequency from a corresponding one of a plurality of received light amount signals output from the plurality of received light amount signals.
- LPFs low-pass filters
- An optical disc device including such a filter unit 106 should be within the scope of the present invention, as long as it is configured to remove components having the above frequencies. If the filter unit 106 includes a plurality of LPFs and does not include a plurality of EQs, the switching unit 105 becomes unnecessary.
- the tracking error detection unit 104 generates a tracking error signal by performing a predetermined operation on a plurality of signals output from the filter unit 106. How the tracking error signal is generated is not important to the present invention.
- the tracking error detection unit 104 may generate the tracking error signal using the arithmetic circuit described above, or may generate the tracking error signal using any known method.
- the control signal generator 102 functions as a tracking controller that drives the lens driver 101 so that the light beam spot follows a track on the recording surface of the optical disk 1 in accordance with the tracking error signal. .
- the filter section 106, the tracking error detection section 104, and the control signal generation section 102 may be realized by software using a computer program or the like, or may be realized by hardware using a circuit or the like. Good. Alternatively, it may be realized by a combination of software and hardware. The same applies to the disc determination unit 108, the management unit 109, the band control unit 107, the switching unit 105, and the switching control unit 103.
- the lens driving unit 101 may be, for example, a mechanical actuator.
- an integrated circuit may be formed by integrating at least the filter unit 106, the tracking error detection unit 104, and the control signal generation unit 102 on one semiconductor chip. Such an integrated circuit functions as a signal processing device that processes a tracking error signal.
- the phase difference method is a method used when the optical disc 1 has pits and is recorded with recording marks.
- the phase of the component detecting the pit or the recording mark in the received light amount signal output from each of the four regions of the received light amount detection unit 6 differs depending on the tracking error in each of the four regions. Detects tracking errors by detecting.
- the received light signal at the point input to the tracking error detection unit 104 is a signal having a high frequency band in which a pit or a recording mark is detected (specifically, a signal of several MHz to several tens MHz in DVD). ) Is required [0085]
- the push-pull method is a method used when the optical disc 1 has a guide groove.
- the light quantity of the first-order diffracted light diffracted by the guide groove of the received light signal output from each of the four areas of the received light detection section 6 differs depending on the tracking error in each of the four areas.
- the frequency band of the component that detected the inner groove is equal to the frequency band where the light beam spot crosses the guide groove due to the eccentricity of the optical disk or the deviation of the chucking (specifically, the band of several tens kHz or less for DVD). . Therefore, the frequency band of the received light amount signal at the point input to the tracking error detection unit 104 may be a band of about 100 kHz or less.
- the frequency band of the laser power modulation component included in the received light signal at the time of recording is several tens of the required frequency band of the received light signal at the point input to the tracking error detection unit 104 as described above. MHz to hundreds of MHz.
- the tracking error detection method is specifically used as follows.
- the phase difference method is used.
- the DVD-RAM uses the push-pull method for both recording and playback.
- DVD-R the push-pull method is used for recording, and the phase difference method is used for reproduction.
- the optical disk device operates as follows.
- the “unnecessary component” includes a laser power modulation component at the time of recording, a frequency band component unrelated to tracking error detection, and the like.
- the optical disk 1 loaded in the optical disk device is a DVD-RAM.
- the switching control unit 103 outputs a signal to the tracking error detection unit 104 so that the tracking error detection method is the push-pull method, and switches the switching unit 105 so that the input of the selector of the switching unit 105 becomes a. Output signal to 105.
- the cutoff frequency of the LPF of the filter unit 106 can be reduced to several hundred kHz. For example, only the signal components in the low frequency band required for tracking error detection by the push-pull method are left, and tracking error detection can be performed normally.
- the switching control section 103 When the optical disk device is in the reproducing operation state and the optical disk 1 loaded in the optical disk device is a DVD-ROM or a DVD-R, the switching control section 103 performs the tracking error detection method. Is output to the tracking error detection unit 104 so that the phase difference method is used, and the switching unit 1 is switched so that the input of the selector of the switching unit 105 becomes b.
- the recording speed (for example, the double speed at the time of recording) differs depending on the use of the optical disk device, the type of the optical disk loaded in the optical disk device, and the like.
- the tracking control gain, the frequency band required for tracking error detection, and the frequency band of the laser power modulation component are different.
- DVD recorders and DVD drives for personal computers often produce a common device, but the recording speed is changed as follows according to the use of the optical disk device.
- the recording power needs to be increased, and accordingly, disturbance due to the modulation component of the laser power (recording power) also increases. Therefore, it is advantageous for tracking detection to lower the LPF cutoff frequency and increase the disturbance cutoff effect.
- the tracking control gain needs to be increased in order to increase the tracking speed of the tracking control. Therefore, it is necessary to detect a tracking error in a high frequency band. For this reason, if the cutoff frequency of the LPF is set too low, the accuracy of the tracking control deteriorates. [0095] Further, as the recording speed increases, the frequency band of the disturbance due to the modulation component of the laser power (recording power) increases.
- the frequency band and size of components necessary for tracking error detection and unnecessary components are strictly different depending on the recording speed (for example, double speed during recording).
- the magnitude and frequency band of the disturbance due to the modulation component of the recording power) and the effect of blocking the LPF against this, securing the frequency band required for tracking error detection, and the balance between the two points The cutoff frequency of the LPF is designed for each recording speed so that it can be obtained.
- the band control unit 107 adjusts the cut-off frequency of the LPF so that the cut-off frequency of the LPF of the filter unit 106 becomes a previously designed value according to the recording speed set in the optical disc device at the time of recording.
- the switching signal is output to the filter unit 106.
- the LPF of the filter unit 106 performs an operation of switching a cutoff frequency according to a signal from the band control unit 107. As a result, signal components necessary for tracking error detection can be left with higher accuracy.
- the components necessary for tracking error detection included in the received light amount signal at the point input to the tracking error detection unit 104 are accurately left, and the Unnecessary components for tracking error detection such as laser power modulation components and noise are removed from the received light amount signal.
- tracking error detection can be performed normally without saturating the signal inside the tracking error detection unit 104.
- highly accurate tracking control can be performed even during high-speed recording.
- the tracking error detection method and the frequency band have been described by taking as an example the case where the optical disc 1 is one of DVD-RAM, DVD-R, and DVD-ROM.
- the type of the optical disc 1 is not limited to the DVD disc described above. Even when the optical disc 1 is an optical disc other than the above-mentioned DVD disc, the present invention can be applied to any optical disc by appropriately matching the tracking error detection method and the frequency band.
- FIG. 2 shows a configuration of an optical disk device according to Embodiment 2 of the present invention.
- Laser diode 202 emits laser light.
- the collimating lens 203 converts the laser light emitted from the laser diode 202 into parallel light.
- the beam splitter 204 allows the parallel light from the collimator lens 203 to pass through the objective lens 205, and also transmits the parallel light (reflected light from the optical disc 1) from the objective lens 205 in the direction in which the force detection lens 207 is located. To separate.
- the focus detection lens 207 has a lens configuration that detects a focus error from the parallel light that has passed through the beam splitter 204 by an astigmatism method, and focuses the light toward the received light amount detection unit 206.
- the objective lens 205 forms a light beam spot on the recording surface of the optical disc 1 by converging the parallel light passing through the collimator lens 203 and the beam splitter 204 on the recording surface of the optical disc 1. Further, the objective lens 205 converts the reflected light from the optical disc 1 into parallel light, and passes the parallel light to the beam splitter 204.
- the lens drive unit 208 moves the light beam spot formed by the objective lens 205 in a direction substantially perpendicular to the recording surface of the optical disc 1.
- the received light amount detection unit 206 has a light receiving surface for detecting the elliptical focal point converged by the focus detection lens 207.
- the light receiving surface is divided into four regions by two boundary lines. Each of the four regions is configured to generate a light reception amount signal corresponding to the light reception amount and output the signal.
- one of the two diagonal directions of the four regions coincides with the major axis direction of the elliptical focal point, and the other of the two diagonal directions of the four regions coincides with the minor axis direction of the elliptical focal point. It is configured to do.
- the filter unit 213 has four sets of low-pass filters (LPF) and conductors. Each LPF corresponds to one of the four received light amount signals output from the four areas of the received light amount detection unit 206. Yes One received light signal power Removes components having frequencies equal to or higher than a predetermined cutoff frequency, and passes other components. Each conductor outputs one corresponding received light amount signal as it is among the four received light amount signals output from the four regions of the received light amount detection unit 206. Also
- Each of the LPFs is configured to be able to switch the cutoff frequency according to a signal output from the switching control unit 210! RU
- the switching control unit 210 changes the switching unit 212 according to the information indicating whether the optical disc device is in the recording operation state or the reproducing operation state and the information indicating the recording speed (for example, double speed during recording). And a signal to filter section 213.
- the management unit 214 stores information indicating whether the optical disc apparatus is in a recording operation state or a reproduction operation state and information indicating a recording speed (for example, a double speed during recording), and switches between these pieces of information. Provided to the control unit 210.
- the switching unit 212 has four 2-input / 1-output selectors. One of the two inputs a and b of each selector is connected to the output of the selector. The input a of each selector is connected to the output of the LPF, and the input b of each selector is connected to a conductor. The LPF and the conductor connected to the inputs a and b of each selector are a set of the LPF and the conductor to which the same received light amount signal is input in the filter unit 213.
- the switching unit 212 switches the input of each selector to a or b at the same time according to the signal output from the switching control unit 210.
- the focus error detection unit 211 generates a focus error signal indicating a shift amount between the light beam spot and the recording surface of the optical disc 1 based on the four signals output from the switching unit 212. Is output.
- the control signal generation unit 209 generates a focus control signal for causing the light beam spot formed by the objective lens 5 to follow the recording surface of the optical disc 1 according to the focus error signal output from the focus error detection unit 211. Output.
- the lens drive unit 208 is substantially perpendicular to the recording surface of the optical disc 1 so that the light beam spot follows the recording surface of the optical disc 1 according to the focus control signal output from the control signal generation unit 209. Move the objective lens 205 in the desired direction.
- the optical disk device shown in FIG. 2 performs focus control for performing focus control. Functions as a device.
- the objective lens 205 functions as a converging unit that forms a light beam spot on the recording surface of the optical disc 1 by converging the light beam on the recording surface of the optical disc 1.
- the convergence means is not limited to the objective lens 205. Any one or more elements can be used as the convergence means as long as they have a function equivalent to the function of the convergence means described above.
- the lens driving unit 208 functions as a moving unit that moves the light beam spot formed by the objective lens 205 in a direction substantially perpendicular to the recording surface of the optical disc 1.
- the moving means is not limited to the lens driving unit 208. Any one or more elements can be used as a transportation means as long as they have the same function as the transportation means described above.
- the received light amount detection unit 206 functions as light detection means having a light receiving surface for detecting the reflected light from the optical disc 1.
- the light receiving surface is divided into a plurality of regions. Each of the plurality of regions is configured to generate a light reception amount signal corresponding to the light reception amount and output the signal.
- the light detection means is not limited to the received light amount detection unit 206. Any one or more elements can be used as the light detecting means as long as they have a function equivalent to the function of the light detecting means described above.
- filter section 213 includes a plurality of conducting wires.
- the filter unit 213 includes a plurality of low-pass filters (LPFs), and each of the plurality of LPFs is a predetermined one of a plurality of received light amount signals output from the light detection means.
- An optical disk device including such a filter unit 213 should be within the scope of the present invention, as long as it is configured to remove a component having a frequency equal to or higher than the cutoff frequency.
- switching section 212 is not required. In this case, outputs from the plurality of LPFs are always provided to the focus error detection unit 211. Alternatively, outputs from a plurality of conductors may always be provided to the focus error detection unit 211 !.
- the focus error detection unit 211 generates a focus error signal by performing a predetermined operation on a plurality of signals output from the filter unit 213. How to generate the focus error signal is not important for the present invention! Focuse The error detection unit 211 may generate the focus error signal using any known method.
- the control signal generation unit 209 functions as a tracking control unit that drives the lens driving unit 208 so that the light beam spot follows the recording surface of the optical disc 1 in accordance with the focus error signal.
- the filter unit 213, the focus error detection unit 211, and the control signal generation unit 209 may be realized by software using a computer program or the like, or may be realized by hardware using a circuit or the like. Is also good. Alternatively, it may be realized by a combination of software and hardware. The same applies to the management unit 214 and the switching control unit 210.
- the lens driving unit 208 may be, for example, a mechanical actuator.
- an integrated circuit may be formed by integrating at least the filter unit 213, the focus error detection unit 211, and the control signal generation unit 209 on one semiconductor chip. Such an integrated circuit functions as a signal processing device that processes a focus error signal.
- the RF signal system and the focus control system share the light reception amount detection unit 206 to detect the light reception amount.
- a reproducing unit (not shown) generates an RF signal and reproduces recorded information.
- the focus error is caused by the non-planarity of the optical disk, the deviation of the chucking, and the like, and its frequency band is several tens kHz or less for DVD. Therefore, the frequency band of the received light amount signal at the point input to the focus error detection unit 211 may be a band of several hundred kHz or less.
- the response frequency of the received light amount detection unit 206 is high for generating an RF signal, and includes a laser power modulation component of several tens to several hundreds MHz at the time of recording.
- the recording speed (for example, the double speed during recording) differs depending on the application of the optical disk device, the type of the optical disk 1 loaded in the optical disk device, and the like.
- Frequency of components necessary for focus control gain and focus error detection The frequency bands and magnitudes of several bands and unnecessary components (particularly, modulation components of laser power (recording power)) are different. This is as described in the first embodiment, and the same applies to the focus control system as to the tracking control system.
- the cutoff frequency of the LPF is made variable, and the following operation is performed.
- the switching control section 210 When the optical disc device is in the recording operation state, the switching control section 210 outputs a signal to the switching section 212 such that the input of the selector of the switching section 212 becomes a. Further, the switching control unit 210 sets the cutoff frequency of the LPF to a high value when the double speed during recording is low, and sets the cutoff frequency of the LPF to a low value when the double speed during recording is high. Thus, a signal for switching the cutoff frequency of the LPF is output to the filter unit 213.
- the laser power modulation component is always removed from the received light amount signal at the point input to the focus error detection unit 211. Further, even when the double speed during recording changes, the components required for the focus error detection unit 211 to detect the focus error always remain in the received light signal. Therefore, focus error detection can be performed normally without being affected by the laser power modulation component. As a result, high-accuracy focus control can be performed even during high-speed rotation.
- the focus error detection method and the frequency band have been described taking the case where the optical disc 1 is a DVD as an example, but the type of the optical disc 1 is not limited to the DVD. Even when the optical disc 1 is an optical disc other than a DVD, the present invention can be applied to an arbitrary optical disc by appropriately setting the frequency band.
- the configuration and operation of the optical disc device have been described with an example where the focus error detection method is the astigmatism method.
- the focus error detection method is limited to the astigmatism method.
- the present invention can be applied to any focus error detection method that is not specific to a particular focus error detection method.
- the switching unit 212 may be eliminated, and the cutoff frequency of the LPF may always be switched according to the double speed not only during recording but also during reproduction. This allows the received light signal to be RF signal components (in the case of DVD, signal components of several MHz to several tens of MHz) included in the signal can be accurately removed according to the speed. As a result, even during reproduction, focus error detection can be performed more accurately, and highly accurate focus control can be performed.
- a filter unit that removes unnecessary components while leaving components necessary for tracking control or focus control is provided immediately after the received light amount detection unit.
- the optical disc device according to the present invention is useful as a DVD multi-recorder, a DVD multi-drive, and the like. Further, the present invention can be applied not only to DVDs but also to any optical disk device that records and reproduces a plurality of media.
Landscapes
- Optical Recording Or Reproduction (AREA)
Abstract
Description
Claims
Priority Applications (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US10/595,476 US20070217294A1 (en) | 2003-10-24 | 2004-10-22 | Tracking Control Apparatus And Method, And Signal Processing Apparatus |
EP04792871A EP1677292A1 (en) | 2003-10-24 | 2004-10-22 | Tracking control device and method, focus control device and method, and signal processing device |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2003-364247 | 2003-10-24 | ||
JP2003364247 | 2003-10-24 |
Publications (1)
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WO2005041178A1 true WO2005041178A1 (ja) | 2005-05-06 |
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Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
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PCT/JP2004/015729 WO2005041178A1 (ja) | 2003-10-24 | 2004-10-22 | トラッキング制御装置および方法、フォーカス制御装置および方法、並びに信号処理装置 |
Country Status (6)
Country | Link |
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US (1) | US20070217294A1 (ja) |
EP (1) | EP1677292A1 (ja) |
KR (1) | KR20060094090A (ja) |
CN (1) | CN1898729A (ja) |
TW (1) | TW200525526A (ja) |
WO (1) | WO2005041178A1 (ja) |
Families Citing this family (6)
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JP4579803B2 (ja) | 2005-09-15 | 2010-11-10 | 東芝サムスン ストレージ・テクノロジー株式会社 | 光ディスク装置 |
US20100195464A1 (en) * | 2007-07-02 | 2010-08-05 | Panasonic Corporation | Integrated circuit, optical disc system and tracking error signal generation method |
BRPI1009810A2 (pt) | 2009-03-26 | 2015-08-25 | Suntory Holdings Ltd | Lisofosfolipídeo aciltransferase. |
JP2012212491A (ja) * | 2011-03-31 | 2012-11-01 | Sanyo Electric Co Ltd | トラッキング制御方法 |
JP2012221523A (ja) * | 2011-04-07 | 2012-11-12 | Sanyo Electric Co Ltd | トラッキング制御方法 |
FR3066023B1 (fr) * | 2017-05-04 | 2019-06-28 | Elichens | Dispositif et procede de mesure et de suivi de la quantite ou concentration d’un composant dans un fluide |
Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS58166541A (ja) * | 1982-03-26 | 1983-10-01 | Hitachi Ltd | 光ディスクにおけるトラッキング制御装置 |
JPH05197988A (ja) * | 1992-01-21 | 1993-08-06 | Matsushita Electric Ind Co Ltd | 光ディスク装置 |
JP2001028129A (ja) * | 1999-07-14 | 2001-01-30 | Sony Corp | 光ディスク装置 |
JP2003085783A (ja) * | 2001-09-12 | 2003-03-20 | Toshiba Corp | 光学式ピックアップ、光学式ディスク記録再生装置、光学式ピックアップ用増幅器 |
-
2004
- 2004-10-22 WO PCT/JP2004/015729 patent/WO2005041178A1/ja not_active Application Discontinuation
- 2004-10-22 EP EP04792871A patent/EP1677292A1/en not_active Withdrawn
- 2004-10-22 US US10/595,476 patent/US20070217294A1/en not_active Abandoned
- 2004-10-22 CN CNA2004800384612A patent/CN1898729A/zh active Pending
- 2004-10-22 KR KR1020067007930A patent/KR20060094090A/ko not_active Application Discontinuation
- 2004-10-26 TW TW093132434A patent/TW200525526A/zh unknown
Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS58166541A (ja) * | 1982-03-26 | 1983-10-01 | Hitachi Ltd | 光ディスクにおけるトラッキング制御装置 |
JPH05197988A (ja) * | 1992-01-21 | 1993-08-06 | Matsushita Electric Ind Co Ltd | 光ディスク装置 |
JP2001028129A (ja) * | 1999-07-14 | 2001-01-30 | Sony Corp | 光ディスク装置 |
JP2003085783A (ja) * | 2001-09-12 | 2003-03-20 | Toshiba Corp | 光学式ピックアップ、光学式ディスク記録再生装置、光学式ピックアップ用増幅器 |
Also Published As
Publication number | Publication date |
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US20070217294A1 (en) | 2007-09-20 |
EP1677292A1 (en) | 2006-07-05 |
TW200525526A (en) | 2005-08-01 |
CN1898729A (zh) | 2007-01-17 |
KR20060094090A (ko) | 2006-08-28 |
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