JP2006236529A - Optical disk recording/playback apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical disk recording/playback apparatus for recording a signal in an optical disk by a laser beam emitted from an optical pickup. <P>SOLUTION: The optical disk recording/playback apparatus comprises: a first laser driving circuit 29 for supplying a driving signal to a first laser diode 1a; a second laser driving circuit 36 for supplying a driving signal to a second laser diode 2a; a first recording pulse generation circuit 28 for generating a first recording pulse signal corresponding to the signal recorded in the first signal recording layer and outputting the first recording pulse signal to the first laser driving circuit 29; and a second recording pulse generation circuit 33 for generating a second recording pulse signal corresponding to the signal recorded in the second signal recording layer and outputting the second recording pulse signal to the second laser driving circuit 36. When the operations of recording signals in the first and second signal recording layers are performed at the same time, the first and second laser diodes 1a and 2a are prevented from simultaneously emitting light at a recording level. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an optical disc recording / reproducing apparatus that performs a signal recording operation on an optical disc with laser light emitted from a laser diode incorporated in an optical pickup.

  In recent years, an optical disk recording / reproducing apparatus using an optical disk called a DVD (Digital Versatile Disc) has become widespread. Such an optical disk recording / reproducing apparatus uses a disk called a CD (Compact Disc) in addition to a DVD disk. It is configured to be able to. As an optical pickup incorporated in an optical disc recording / reproducing apparatus that can use both of these discs, there are a laser diode that emits a laser beam having a wavelength suitable for the DVD recording density and a laser having a wavelength suitable for the CD recording density. Two laser diodes having different emission wavelengths of laser diodes that emit light are provided, and the laser diodes are switched according to the optical disk to be used.

  With DVD and CD, the thickness of the transparent substrate up to the signal recording layer is greatly different from 0.6 mm and 1.2 mm, respectively, so that optical pickups compatible with DVD and CD have optical characteristics suitable for each disk. The NA (numerical aperture) required for the objective lens is different. Therefore, in the case where DVD and CD are supported by a single objective lens, it can be realized by using an objective lens that acts as an NA for each wavelength of laser light suitable for each disk.

Among optical discs, a two-layer disc having two signal recording layers has been developed, and an optical disc recording / reproducing apparatus capable of recording on each signal layer has been commercialized. In addition, a technique for recording a signal on each signal layer of such a two-layer disc has been developed (see, for example, Patent Document 1).
JP-A-9-282710

  Although the technique described in Patent Document 1 can perform the signal recording operation to the two signal recording layers provided in the optical disc, it cannot simultaneously perform the signal recording operation to the two signal recording layers. I can't.

  The present invention is intended to provide an optical disc recording / reproducing apparatus that can solve such a problem.

  The present invention relates to a first laser driving circuit that supplies a driving signal to a first laser diode that emits laser light applied to a first signal recording layer of an optical disc, and a laser light applied to a second signal recording layer of the optical disc. A second laser driving circuit for supplying a driving signal to a second laser diode that emits light, and a first recording pulse signal corresponding to the signal recorded in the first signal recording layer, and output to the first laser driving circuit And a second recording pulse generating circuit that generates a second recording pulse signal according to a signal recorded in the second signal recording layer and outputs the second recording pulse signal to the second laser driving circuit, When simultaneously performing signal recording operations on the first signal recording layer and the second signal recording layer, the first laser diode and the second laser diode are simultaneously at a recording level. And it is configured so as not to light.

  In addition, the present invention provides a higher recording operation on the first signal recording layer by the output signal of the first recording pulse generation circuit than the recording operation on the second signal recording layer by the output signal of the second recording pulse generation circuit. When performing at the density, an exclusive OR output of the output signal of the first recording pulse generating circuit and the output signal of the second recording pulse generating circuit is supplied to the second laser driving circuit.

  The present invention provides a control operation for focusing the laser light emitted from the first laser diode on the first signal recording layer and a control for focusing the laser light emitted from the second laser diode on the second signal recording layer. A focus servo circuit for performing the operation is provided, and when the signal recording operation to the first signal recording layer and the second signal recording layer is performed, the laser light emitted from the first laser diode is combined with the first signal recording layer. It is configured to perform a focus control operation that causes a focus.

  The present invention also provides a control operation for focusing the laser light emitted from the first laser diode on the first signal recording layer and a control for focusing the laser light emitted from the second laser diode on the second signal recording layer. A focus servo circuit for performing the operation is provided, and when the focus control operation for focusing the laser beam emitted from the first laser diode on the first signal recording layer is performed by the focus servo circuit, the focus servo circuit emits the laser light. The optical system of the optical pickup is set so that the laser beam to be focused on the second signal recording layer.

  The present invention relates to a first laser driving circuit that supplies a driving signal to a first laser diode that emits laser light applied to a first signal recording layer of an optical disc, and a laser light applied to a second signal recording layer of the optical disc. A second laser driving circuit for supplying a driving signal to a second laser diode that emits light, and a first recording pulse signal corresponding to the signal recorded in the first signal recording layer, and output to the first laser driving circuit And a second recording pulse generating circuit that generates a second recording pulse signal according to a signal recorded in the second signal recording layer and outputs the second recording pulse signal to the second laser driving circuit, When simultaneously performing signal recording operations on the first signal recording layer and the second signal recording layer, the first laser diode and the second laser diode are simultaneously at a recording level. Since it is configured so as not to light, it is possible to suppress the temperature rise of the optical pickup.

  In addition, since the two laser diodes do not emit laser light at a high output at the same time, the mutual interference of the laser light can be suppressed, resulting in a focus servo operation, a laser output control operation, and the like. It has the advantage of not having an adverse effect.

  In the present invention, the recording operation on the first signal recording layer by the output signal of the first recording pulse generation circuit is higher than the recording operation on the second signal recording layer by the output signal of the second recording pulse generation circuit. Since the exclusive OR output of the output signal of the first recording pulse generation circuit and the output signal of the second recording pulse generation circuit is supplied to the second laser driving circuit when performing at the density, the first laser diode And the radiation operation of the second laser diode can be easily controlled.

The present invention provides a control operation for focusing the laser light emitted from the first laser diode on the first signal recording layer and a control for focusing the laser light emitted from the second laser diode on the second signal recording layer. A focus servo circuit for performing the operation is provided, and when the signal recording operation to the first signal recording layer and the second signal recording layer is performed, the laser light emitted from the first laser diode is combined with the first signal recording layer. Since the focus control operation for focusing is performed, that is, the focus control operation for the first signal recording layer performing the high-density recording operation is performed, the recording operation can be performed accurately.

  The present invention also provides a control operation for focusing the laser light emitted from the first laser diode on the first signal recording layer and a control for focusing the laser light emitted from the second laser diode on the second signal recording layer. A focus servo circuit for performing the operation is provided, and when the focus control operation for focusing the laser beam emitted from the first laser diode on the first signal recording layer is performed by the focus servo circuit, the focus servo circuit emits the laser light. Since the optical system of the optical pickup is set so that the laser beam to be focused on the second signal recording layer, the recording operation on the second signal recording layer can be performed without any trouble.

  The present invention is an optical disc recording / reproducing apparatus that uses an optical pickup incorporating two laser diodes, and is configured to simultaneously perform recording operations on two signal recording layers provided on an optical disc. ing.

  FIG. 1 is a block diagram showing an embodiment of an optical disk recording / reproducing apparatus according to the present invention. In this embodiment, the optical pickup has a configuration corresponding to DVD and CD, and a first laser diode that emits a first laser beam having a first wavelength of 645 nm to 675 nm suitable for DVD, for example, 650 nm. A laser unit 1 composed of 1a and a light emitting / receiving unit 2 including a second laser diode 2a that emits a second laser beam having a second wavelength of 765 nm to 805 nm, for example, 780 nm, suitable for CD are incorporated. ing.

  The light receiving and emitting unit 2 includes a photodetector 3 that receives reflected light of the second laser light reflected from the optical disk D together with the second laser diode 2a, and is provided in the same package. An optical path formed with a diffraction grating that separates the reflected light of the second laser light from the optical path of the second laser light emitted from the second laser diode 2a and conducts the optical path separation to the light detector 3 in the opening. A hologram element 4 acting as a separation element is arranged. The diffraction grating for optical path separation is formed on the surface of the hologram element 4 on the side of the optical disc D, and the surface of the hologram element 4 on the side of the second laser diode 2a generates diffraction that generates three beams used for the tracking control operation. A lattice is formed.

  A first laser beam having a first wavelength emitted from a first laser diode 1 a incorporated in the laser unit 1 is a diffraction grating 6 provided in front of an opening 5 formed in the laser unit 1. The first-order diffracted light used for the tracking control operation is diffracted so as to be generated, and then the polarization direction is adjusted by the half-wavelength plate 7 so that the birefringence in the transparent substrate of the optical disk D is reduced.

  The first laser light thus adjusted is incident on the polarizing filter surface 8a of the polarizing prism 8 from the transmission direction. The polarizing filter surface 8 a is set to have a film characteristic that transmits the first laser light having the polarization direction adjusted by the half-wave plate 7. Therefore, the first laser light passes through the polarizing filter surface 8 a of the polarizing prism 8. After being transmitted and converted into parallel light by the collimator lens 9, the light enters the parallel plate type beam splitter 10 from the transmission direction.

  The beam splitter 10 plays a role of arranging the laser unit 1 and the light receiving / emitting unit 2 so as to be in separate optical paths, and is a filter that serves as a reflection surface for reflecting the second laser light emitted from the light receiving / emitting unit 2. The surface 10a has a wavelength-selective dichroic filter characteristic, and is provided with a transmission / reflection coating having a characteristic that the first laser beam of 650 nm is substantially totally transmitted and the second laser beam of 780 nm is substantially totally reflected. Yes.

  Accordingly, the first laser light emitted from the first laser diode 1a is transmitted by the beam splitter 10 and then reflected by the rising mirror 11, so that the optical axis is bent at a right angle. The first laser light reflected by the rising mirror 11 passes through the wavelength-selective quarter-wave plate 12 that effectively acts only on the 650-nm laser light and is incident on the objective lens 13. The light is converged by the objective lens 13 and irradiated onto the optical disk D.

  As described above, the first laser light emitted from the first laser diode 1a is applied to the optical disk D. The first laser light reflected from the optical disk D returns to the objective lens 13 and passes through the optical path that has come. Then, it passes through the beam splitter 10 and is returned to the polarizing prism 8 through the collimator lens 9.

  The first laser light returning to the polarizing prism 8 in this way passes through the quarter-wave plate 12 having wavelength selectivity, which acts effectively only on the first laser light, on the outward path and the return path to the optical disk D twice. Since it passes, the polarization direction is rotated by half wavelength. Therefore, the first laser beam, which has been P-polarized on the way to the optical disc D, is incident on the polarizing prism 8 as S-polarized light. As a result, the first laser light returning to the polarizing prism 8 is reflected by the polarizing filter surface 8a and is applied to the photodetector 15 via the anamorphic lens 14 which gives an astigmatism component for generating a focus error component. Led.

  The light detector 15 has a light receiving surface divided into a plurality of light receiving regions, and is configured to receive the first laser light reflected from the optical disc D. Such a configuration is well known and will not be described. However, a reproduction signal, a focusing control signal and a tracking control signal of a signal recorded on the optical disc D based on a signal obtained from such a light receiving area, or a tilt control signal. Is configured to generate

  Reference numeral 16 denotes a front-end processing circuit to which a signal obtained from the photodetector 15 is input, and calculates the input signal to generate a reproduction signal, a focusing control signal and a tracking control signal, or a tilt control signal. It is configured.

  On the other hand, the second laser light emitted from the second laser diode 2a incorporated in the light emitting / receiving unit 2 is separated into three beams via the hologram element 4 and emitted from the light emitting / receiving unit 2, thereby divergent. After the divergence angle is adjusted by the lens 17, the light is further applied to the filter surface 10 a of the beam splitter 10 through the liquid crystal lens 18 and the half-wave plate 19.

  The second laser light applied to the filter surface 10a of the beam splitter 10 is reflected by the rising mirror 11 after the optical axis is changed by the filter surface 10a, and the optical axis becomes perpendicular to the surface of the optical disc D. Bend like so. The second laser light reflected by the rising mirror 11 passes through the quarter-wave plate 12 and is incident on the objective lens 13, converged by the objective lens 13, and irradiated onto the optical disk D.

  The objective lens 13 is provided with a diffraction grating (not shown) on the incident surface, and each laser beam having a different wavelength for DVD and CD due to the balance between the diffraction grating and refraction due to the aspherical shape of the objective lens 13 itself. On the other hand, it is set so that desired characteristics suitable for recording / reproducing of each disk can be exhibited. In this case, a first laser beam suitable for a DVD is made incident in a predetermined area by parallel light, and a second laser light suitable for a CD is made incident in a predetermined area with a predetermined divergence angle for recording and reproduction of DVD and CD, respectively. An appropriate NA and aberration corrected laser spot is set.

  The second laser light reflected from the signal surface of the optical disk D returns to the objective lens 13 and returns to the beam splitter 10 via the quarter-wave plate 12 and the rising mirror 11. Then, the second laser light returned to the beam splitter 10 is reflected by the filter surface 10 a and returned to the light emitting / receiving unit 2 via the half-wave plate 19, the liquid crystal lens 18 and the divergent lens 17. The second laser light thus returned to the light emitting / receiving unit 2 is irradiated to the photodetector 3 with the optical axis being bent by the hologram element 4.

  The light detector 3 has a light receiving surface divided into a plurality of light receiving regions, and is configured to receive the second laser light reflected from the optical disc D. Such a configuration is well known and will not be described. However, a reproduction signal, a focusing control signal and a tracking control signal of a signal recorded on the optical disc D based on a signal obtained from such a light receiving area, or a tilt control signal. Is configured to generate Since the signal generated by the photodetector 3 is input to the front-end processing circuit 16, the front-end processing circuit 16 calculates the input signal to generate a reproduction signal, a focusing control signal, and a tracking control. It is configured to generate a signal.

  The liquid crystal lens 18 has a small power by changing the degree of phase change concentrically in a stepwise manner depending on the liquid crystal arrangement, but is designed to have a lens action.

  Here, the relationship between the optical disk D used in the present invention and the objective lens 13 will be described with reference to FIG. In FIG. 2, the optical disk D has a transparent first protective layer D1, a first signal recording layer S1, and a transparent second layer from the side on which the first laser beam and the second laser beam converged by the objective lens 13 are incident. A protective layer D2, a transparent third protective layer D3, a second signal recording layer S2, and a transparent third protective layer D4 are provided.

  In such a configuration, the first laser beam converged by the objective lens 13 is focused on the first signal recording layer S1, and the second laser beam is focused on the second signal recording layer S2. It is configured. Further, the position of the first signal recording layer S1 of the optical disc D is disposed at a position set by the DVD standard from the laser light incident surface, and the position of the second signal recording layer S2 is CD from the laser light incident surface. It is arranged at the position set by the standard. The optical disc D includes a first disc composed of a first protective layer D1, a first signal recording layer S1, and a transparent second protective layer D2, a transparent third protective layer D3, a second signal recording layer S2, and a transparent first layer. It is configured to be manufactured by bonding a second disk made of three protective layers D4 with an adhesive SS.

  Next, the control operation of the optical pickup for the optical disk D configured as described above will be described. In the block diagram shown in FIG. 1, reference numeral 20 denotes a servo circuit that performs various control operations based on various control signals generated by the front end processing circuit 16.

  That is, the servo circuit 20 performs a signal recording operation on the first signal recording layer S1 provided corresponding to the DVD standard and a reproduction operation of a signal recorded on the first signal recording layer S1. Various servo signals are generated based on various control signals generated by the front-end processing circuit 16 based on the signals obtained from the photodetector 15, that is, focus control signals, tracking control signals, and tilt control signals. It is configured.

The servo circuit 20 performs a signal recording operation on the second signal recording layer S2 provided corresponding to the CD standard and a reproduction operation of a signal recorded on the second signal recording layer S2. The various control signals generated by the front-end processing circuit 16 based on the signal obtained from the photodetector 3, that is, the various servo signals are generated based on the focus control signal and the tracking control signal. .

  Reference numeral 21 denotes an actuator driver circuit to which various control signals generated and output from the servo circuit 20 are supplied. The actuator driver circuit 21 is provided to displace the objective lens 13 in the focus adjustment direction, tracking adjustment direction, and tilt adjustment direction. The drive signals are supplied to various drive coils 22.

  When performing the recording / reproducing operation on the first signal recording layer S1 of the optical disc D, the first signal recording layer based on various control signals generated from the front end processing circuit 16 based on the signal obtained from the photodetector 15 is used. An optical pickup control operation for S1, that is, a focus control operation, a tracking control operation, and a tilt control operation are performed. Similarly, when the recording / reproducing operation for the second signal recording layer S2 of the optical disc D is performed, the second signal based on various control signals generated from the front end processing circuit 16 based on the signal obtained from the photodetector 3 is used. A control operation of the optical pickup for the recording layer S2, that is, a focus control operation and a tracking control operation are performed.

  Further, when the signal recording operation to the first signal recording layer S1 and the signal recording operation to the second signal recording layer S2 are performed simultaneously, each control operation of the optical pickup for the first signal recording layer S1 described above. Is configured to do. Then, when the first laser beam is focused on the first signal recording layer S1 by the focus control operation on the first signal recording layer S1, the positional relationship of the optical system is set accurately. The second laser beam can be focused on the second signal recording layer S2.

  By accurately designing the optical system in this way, the focus operation for the second signal recording layer S2 can be performed without any trouble in the recording / reproducing operation even if only the focus control operation for the first signal recording layer S1 is performed. However, more accurate focus control operation can be performed by controlling the liquid crystal lens 18 by the optical path length adjusting circuit 23 and the liquid crystal driver circuit 24.

  When the focus control operation for focusing the first laser light emitted from the first laser diode 1a on the first signal recording layer S1 is performed, it is obtained from the photodetector 3 incorporated in the light emitting / receiving unit 2. A signal is input to the front-end processing circuit 16, and a focus error signal for the second signal recording layer S2 of the second laser light is generated from the front-end processing circuit 16.

  When such a focus error signal is input to the optical path length adjustment circuit 23, an adjustment signal is output from the optical path length adjustment circuit 23 to the liquid crystal driver circuit 24. When such an adjustment signal is input to the liquid crystal driver circuit 24, a drive signal is supplied from the liquid crystal driver circuit 24 to the liquid crystal lens 18. When such a drive signal is supplied from the liquid crystal driver circuit 24 to the liquid crystal lens 18, an adjustment operation is performed in a direction in which the focus error signal is reduced by the concave lens action of the liquid crystal lens 18. By performing such a control operation, the focus control operation for the second signal recording layer S2 can be performed independently of the focus control operation for the first signal recording layer S1.

In such a focus control operation for the second signal recording layer S2, if the power intensity of the concave lens action of the liquid crystal lens 18 is set for each optical disc in consideration of the reaction speed of the liquid crystal element in the liquid crystal lens 18, the surface deflection of the optical disc will occur. However, if the power intensity of the concave lens action of the liquid crystal lens 18 is set for each predetermined position in the radial direction on the optical disc, the optical disc in the radial direction of the optical disc can be dealt with. It can cope with the warp of the disc.

  As described above, the control operation of the optical pickup according to the present invention is performed. Next, a signal recording system circuit will be described.

  In FIG. 1, reference numeral 25 denotes a first signal buffer circuit for temporarily storing a first recording signal recorded in the first signal recording layer S1 output from a host device such as a personal computer, and is constituted by a RAM or the like. ing. Reference numeral 26 denotes a first signal processing circuit, which is configured to control a storing operation and a reading operation of the first recording signal stored in the first signal buffer circuit 25.

  Reference numeral 27 denotes a first recording signal generation circuit to which the first recording signal output from the first signal processing circuit 26 is input, and conforms to the standard of the signal recorded in the first signal recording layer S1, that is, the DVD standard. Are configured to perform an encoding process operation. Reference numeral 28 denotes a first recording pulse generation circuit to which the first recording signal output from the first recording signal generation circuit 27 is input, and is configured to generate a first recording pulse signal corresponding to the DVD standard. . Reference numeral 29 denotes a first laser driving circuit to which the first recording pulse signal generated from the first recording pulse generating circuit 28 is input, and a driving signal corresponding to the input first recording pulse signal is supplied to the first laser diode 1a. It is comprised so that it may supply.

  Reference numeral 30 denotes a second signal buffer circuit for temporarily storing a second recording signal recorded in the second signal recording layer S2 output from the host device, and is constituted by a RAM or the like. Reference numeral 31 denotes a second signal processing circuit, which is configured to control a storing operation and a reading operation of the second recording signal stored in the second signal buffer circuit 30.

  Reference numeral 32 denotes a second recording signal generation circuit to which the second recording signal output from the second signal processing circuit 31 is input, and conforms to the standard of the signal recorded in the second signal recording layer S2, that is, the CD standard. Are configured to perform an encoding process operation. Reference numeral 33 denotes a second recording pulse generation circuit to which the second recording signal output from the first recording signal generation circuit 32 is input, and is configured to generate a second recording pulse signal corresponding to the CD standard. .

  34 is an exclusive OR circuit to which the first recording pulse signal output from the first recording pulse generation circuit 28 and the second recording pulse signal output from the second recording pulse generation circuit 33 are input, and 35 is the exclusive OR circuit. AND circuit to which the output signal of the logical OR circuit 34 and the second recording pulse signal output from the second recording pulse generation circuit 33 are input, and 36 is the first input of the recording pulse signal output from the AND circuit 35. A two-laser drive circuit configured to supply a drive signal corresponding to the input recording pulse signal to the second laser diode 2a.

  In such a configuration, each of the first signal recording layer S1 and the second signal recording layer S2 provided on the optical disc D is provided with meandering grooves called pregrooves, and a wobble signal obtained from the pregrooves. It is comprised so that a synchronizing signal and position information data may be extracted from. By using the synchronization signal and position information data extracted in this way, the rotation speed control operation, the signal processing operation, the recording start position search operation, and the like of the optical disc D are performed. In addition, the signal tracks formed in the first signal recording layer S1 and the second signal recording layer S2 are secondly recorded at a position corresponding to the signal track of the first signal recording layer S1 where high density recording is performed. The signal tracks of the signal recording layer S2 are related to each other.

As described above, the optical disk recording / reproducing apparatus according to the present invention is configured. Next, the operation will be described. First, the operation of recording a DVD standard signal on the first signal recording layer S1 provided on the optical disc D will be described.

  When a command signal for performing a recording operation only on the first signal recording layer S1 is output from the host device to the optical disc recording / reproducing device, a system control circuit (not shown) incorporated in the optical disc recording / reproducing device. It can be switched to the state where the recording operation is performed. A drive signal is supplied from the first laser drive circuit 29 to the first laser diode 1a. The level of the drive signal is a level at which laser light for performing a reproduction operation is emitted, and the first signal of the optical disc D There is no influence on the signal of the recording layer S1.

  The first laser light emitted from the first laser diode 1a is applied to the first signal recording layer S1 of the optical disc D through the optical path described above. In this way, the first laser light is applied to the first signal recording layer S1, and the first laser light reflected from the first signal recording layer S1 passes through the optical path described above to the photodetector 15. Irradiated.

  When the photodetector 15 is irradiated with the first laser light reflected from the first signal recording layer S1 of the optical disc D, a focus control signal, a tracking control signal, and a tilt control signal are generated from the photodetector 15. Input to the front-end processing circuit 16. When such a signal is input to the front end processing circuit 16, a focus control signal, a tracking control signal, and a tilt control signal are output from the front end processing circuit 16 to the servo circuit 20.

  When such a focus control signal, tracking control signal, and tilt control signal are input to the servo circuit 20, a control signal for performing each control operation is output from the servo circuit 20 to the actuator driver circuit 21. As a result, a drive signal is supplied from the actuator driver circuit 21 to each coil constituting the drive coil 22 incorporated in the optical pickup.

  As a result of the drive signal being supplied from the actuator driver circuit 21 to the coils incorporated in the drive coil 22, that is, the focusing coil, tracking coil, and tilt coil, the first laser beam is combined with the first signal recording layer S1. A focus control operation for focusing, a tracking control operation for following a signal track formed in the first signal recording layer S1, and a tilt control operation for controlling an angle with respect to the first signal recording layer S1 can be performed.

  By performing the above-described control operation, it is possible to perform the read operation of the signal recorded by the pregroove in the first signal recording layer S1, and therefore by using the synchronization signal extracted from the read signal. For example, the rotation speed of the optical disk D can be controlled while the linear speed is constant. Further, the irradiation position of the first laser beam can be moved from the position information data extracted from the read signal to a position where the signal recording operation is started. Since such an operation can be performed by a known technique, the description thereof is omitted.

  When the above-described operation is performed, the DVD standard first recording signal transmitted from the host device is stored in the first signal buffer circuit 25 by the control operation of the first signal processing circuit 26. Then, when the first laser beam reaches the position where the recording operation is started, the first recording signal stored in the first signal buffer circuit 25 is read, and the first recording signal is the first recording signal. This is input to the recording signal generation circuit 27.

When the first recording signal is input to the first recording signal generation circuit 27 in this way, the encoding processing operation by the first recording signal generation circuit 27, that is, the operation of generating a block-unit recording signal corresponding to the DVD standard. Is done. The first recording signal corresponding to the DVD standard generated by the encoding processing operation of the first recording signal generation circuit 27 is input to the first recording pulse generation circuit 28.

  When such a first recording signal is input to the first recording pulse generation circuit 28, the first recording pulse signal generation operation is performed by the first recording pulse generation circuit 28, as shown in FIG. Such a first recording pulse signal is generated and output, and the first recording pulse signal is input to the first laser driving circuit 29.

  When such a first recording pulse signal is input to the first laser driving circuit 29, a first laser beam having a recording level set corresponding to the recording characteristics of the first signal recording layer S1 of the optical disc D is emitted. A drive signal is supplied from the first laser drive circuit 29 to the first laser diode 1a. Since such a drive signal is set to a level corresponding to the first recording pulse signal shown in FIG. 3A, a signal corresponding to the change is recorded in the first signal recording layer S1. become. As a result of such an operation, a signal recording operation according to the DVD standard can be performed on the first signal recording layer S1.

  The operation of recording the DVD standard signal on the first signal recording layer S1 provided on the optical disc D is performed as described above. Next, the operation of recording the CD standard signal on the second signal recording layer S2 is performed. explain.

  When a command signal for performing a recording operation only on the second signal recording layer S2 is output from the host device to the optical disc recording / reproducing apparatus, a system control circuit (not shown) incorporated in the optical disc recording / reproducing apparatus It can be switched to the state where the recording operation is performed. A drive signal is supplied from the second laser drive circuit 36 to the second laser diode 2a. The level of the drive signal is a level at which laser light for performing a reproduction operation is emitted, and the second signal of the optical disc D There is no influence on the signal of the recording layer S2.

  The second laser light emitted from the second laser diode 2a is applied to the second signal recording layer S2 of the optical disc D through the optical path described above. In this way, the second laser light is irradiated onto the second signal recording layer S2, and the second laser light reflected from the second signal recording layer S2 passes through the optical path described above to the photodetector 3. Irradiated.

  When the photodetector 3 is irradiated with the second laser light reflected from the second signal recording layer S2 of the optical disc D, a focus control signal and a tracking control signal are generated from the photodetector 3, and a front-end processing circuit is generated. 16 is input. When such a signal is input to the front end processing circuit 16, a focus control signal and a tracking control signal are output from the front end processing circuit 16 to the servo circuit 20.

  When such a focus control signal and tracking control signal are input to the servo circuit 20, a control signal for performing each control operation is output from the servo circuit 20 to the actuator driver circuit 21. As a result, a drive signal is supplied from the actuator driver circuit 21 to each coil constituting the drive coil 22 incorporated in the optical pickup.

  As a result of the drive signal supplied from the actuator driver circuit 21 to the coil incorporated in the drive coil 22, that is, the focusing coil and the tracking coil, the focus for focusing the second laser beam on the second signal recording layer S2 The control operation and the tracking control operation for following the signal track formed in the second signal recording layer S2 can be performed.

  By performing the above-described control operation, it is possible to perform the read operation of the signal recorded in the second signal recording layer S2 by the pregroove. Therefore, by using the synchronization signal extracted from the read signal, For example, the rotation speed of the optical disk D can be controlled while the linear speed is constant. Further, the irradiation position of the second laser beam can be moved from the position information data extracted from the read signal to a position where the signal recording operation is started. Since such an operation can be performed by a known technique, the description thereof is omitted.

  When the operation described above is performed, the CD standard second recording signal transmitted from the host device is stored in the second signal buffer circuit 30 by the control operation of the second signal processing circuit 31. Then, when the second laser beam reaches the position where the recording operation is started, the second recording signal stored in the second signal buffer circuit 30 is read out, and the second recording signal is stored in the second recording signal. This is input to the recording signal generation circuit 32.

  When the second recording signal is input to the second recording signal generation circuit 32 in this way, the encoding processing operation by the second recording signal generation circuit 32, that is, the operation of generating a recording signal in block units corresponding to the CD standard. Is done. The second recording signal corresponding to the CD standard generated by the encoding processing operation of the second recording signal generation circuit 32 is input to the second recording pulse generation circuit 33.

  When such a second recording signal is input to the second recording pulse generation circuit 33, the second recording pulse generation circuit 33 generates a second recording pulse signal, which is shown in FIG. Such a second recording pulse signal is generated and output. The second recording pulse signal output from the second recording pulse generation circuit 33 is input to the exclusive OR circuit 34. In this case, the first recording pulse is generated at the other input terminal of the exclusive OR circuit 34. An L (low) level signal that is an output signal of the circuit 28 is being input.

  Accordingly, a pulse signal having the same level as the output signal of the second recording pulse generation circuit 33 is output to the output terminal of the exclusive OR circuit 34. The output terminal of the AND circuit 35 to which the output signal of the exclusive OR circuit 34 and the second recording pulse signal output from the second recording pulse generation circuit 33 are input has a waveform shown in FIG. A recording pulse signal is output, and the recording pulse signal is input to the second laser driving circuit 36.

  Thus, the recording pulse signal input to the second laser driving circuit 36 is the same pulse signal as the second recording pulse signal output from the second recording pulse generating circuit 33, and the second laser driving circuit 36 The recording pulse signal input to is a second recording pulse signal.

  When such a second recording pulse signal is input to the second laser drive circuit 36, a second laser beam having a recording level set corresponding to the recording characteristics of the second signal recording layer S2 of the optical disc D is emitted. The drive signal is supplied from the first laser drive circuit 36 to the second laser diode 2a. Since such a drive signal is set to a level corresponding to the second recording pulse signal shown in FIG. 3B, a signal corresponding to the change is recorded in the second signal recording layer S2. become. As a result of such an operation, a signal recording operation according to the CD standard can be performed on the second signal recording layer S2.

  As described above, the operation when the signal recording operation to the first signal recording layer S1 and the second signal recording layer S2 is performed independently is performed. Next, the first signal recording layer S1 and the second signal recording operation are performed. The operation in the case of simultaneously performing the signal recording operation on the recording layer S2 will be described.

The control operation of the optical pickup in such a case is performed on the first signal recording layer S1 that performs the high-density recording operation. When such an operation is performed, the focus control operation and the tracking control operation for the second signal recording layer S2 are performed by setting the optical system, and the adjustment operation for the liquid crystal lens 18 by the optical path length adjustment circuit 23 and the liquid crystal driver circuit 24. The focus control operation can be improved.

  Further, since the rotation control operation of the optical disc D is performed on the first signal recording layer S1, the recording operation of the second signal recording layer S2 corresponds to the rotational linear velocity of the first signal recording layer S1. It is necessary to perform processing operations. A technique for performing signal processing corresponding to such a recording speed is performed by changing the frequency of the recording clock signal in accordance with the speed of the signal obtained from the second signal recording layer S2, and this technique is well known. Therefore, the description thereof is omitted.

  When the recording operation to the first signal recording layer S1 and the second signal recording layer S2 is simultaneously performed, the control operation for the optical pickup is performed as described above. In this state, the first signal buffer circuit 25, the processing generation operation for the first recording signal by the first signal processing circuit 26 and the first recording signal generation circuit 27, and the generation operation of the first recording pulse signal by the first recording pulse generation circuit 28 are performed as described above. . In this state, the second signal buffer circuit 30, the second signal processing circuit 31, and the second recording signal generation circuit 32 perform processing generation operations on the second recording signal, and the second recording pulse generation circuit 33 performs the second generation processing. The operation of generating the two recording pulse signals is performed as described above.

  As a result of the processing generation operation of each signal described above, the first recording pulse signal having the waveform shown in FIG. 3A is output from the output terminal of the first recording pulse generation circuit 28, and the second recording pulse generation circuit 33. The second recording pulse signal having the waveform shown in FIG.

  In such a state, when the first recording pulse signal and the second pulse signal having the waveforms shown in FIGS. 3A and 3B are input to the exclusive OR circuit 34, the exclusive OR circuit 34 A pulse signal having a waveform shown in FIG. 3C is output to the output terminal. Then, the signal of the waveform shown in FIG. 3C which is the output signal of the exclusive OR circuit 34 and the second recording pulse signal generated by the second recording pulse generating circuit 33 (B of FIG. The recording pulse signal having the waveform shown in FIG. 3D is output to the output terminal of the AND circuit 35 to which the signal having the waveform shown in FIG.

  As described above, when the signal recording operation to the first signal recording layer S1 and the second signal recording layer S2 is simultaneously performed, the first laser driving circuit 29 includes the first signal shown in FIG. A recording pulse signal is input, and the recording pulse signal shown in FIG. 3D is input to the second laser driving circuit 36. Accordingly, since the drive signal corresponding to the first recording pulse signal having the waveform shown in FIG. 3A is supplied from the first laser driving circuit 29 to the first laser diode 1a, the first signal to the first signal recording layer S1 is supplied. The recording operation of the recording signal can be performed.

  Further, since the recording pulse signal shown in FIG. 3D is supplied from the second laser driving circuit 36 to the second laser diode 2a, the recording operation to the second signal recording layer S2 can be performed. In such a case, the first signal recording layer S2 is generated by a pulse signal having a narrow interval generated corresponding to the first recording pulse signal during the H (high) level period of the second recording pulse signal shown in FIG. A signal will be recorded on.

  In the second signal recording layer S2 where the signal recording operation is performed at a low density, a signal recorded with a pulse signal having a narrow interval is not read as data, and the waveform shown in FIG. Therefore, the signal recording operation to the second signal recording layer S2 can be performed according to the CD standard.

The first recording pulse signal shown in FIG. 3A used for the signal recording operation on the first signal recording layer S1 and the signal recording operation shown in FIG. As can be seen from comparison with the recording pulse signal shown in D), when the level of one recording pulse signal is at H level, the level of the other recording pulse signal is at L level. Therefore, the first laser diode 1a and the second laser diode 2a do not perform the radiation operation at the H level, that is, the recording level at the same time.

  As described above, when the simultaneous recording operation to the first signal recording layer S1 and the second signal recording layer S2 is performed, the first laser diode 1a and the second laser diode 2a simultaneously perform the radiation operation of the laser light at a high output. Since this is not performed, the temperature rise of the optical pickup can be suppressed. In addition, since the other laser beam does not adversely affect the reflected light used to control the optical system of the optical pickup, the focus control operation, tracking control operation and tilt control operation must be performed accurately. I can do it.

  The first laser drive circuit 29 and the second laser drive circuit 36 that supply drive signals to the first laser diode 1a and the second laser diode 2a monitor the level of laser light emitted from each laser diode. Thus, the laser output automatic adjustment circuit that suppresses the level to a predetermined level is provided. However, since the influence of the other laser beam can be suppressed, the laser output adjustment operation can be performed accurately.

  In this embodiment, the DVD standard method is used for high-density recording and the CD standard is used for low-density recording, but other standards can of course be used.

1 is a block circuit diagram showing an embodiment of an optical disc recording / reproducing apparatus according to the present invention. It is sectional drawing which shows one Example of the optical disk based on this invention. It is a signal waveform diagram for demonstrating operation | movement of this invention.

Explanation of symbols

D Optical disc
1 Laser unit 1a First laser diode
2 Light emitting / receiving unit 2a Second laser diode
3 Photodetector 13 Objective Lens 15 Photodetector 16 Front End Processing Circuit 20 Servo Circuit 21 Actuator Driver Circuit 22 Drive Coil 25 First Signal Buffer Circuit 26 First Signal Processing Circuit 27 First Recording Signal Generation Circuit 28 First Recording Pulse Generation circuit 29 First laser drive circuit 30 Second signal buffer circuit 31 Second signal processing circuit 32 Second recording signal generation circuit 33 Second recording pulse generation circuit 36 Second laser drive circuit

Claims (4)

Laser light used on an optical disc provided with two signal recording layers, a first signal recording layer and a second signal recording layer, from the incident light surface side on which the laser light is incident and which is irradiated to the first signal recording layer An optical disk recording / reproducing apparatus including an optical pickup in which a first laser diode that emits light and a second laser diode that emits laser light emitted to the second signal recording layer are incorporated, and the first laser diode A first laser driving circuit for supplying a driving signal to the second laser driving circuit, a second laser driving circuit for supplying a driving signal to the second laser diode, and a first recording pulse signal corresponding to the signal recorded on the first signal recording layer And a first recording pulse generating circuit for outputting the first recording pulse signal to the first laser driving circuit, and the second signal recording. A second recording pulse generation circuit that generates a second recording pulse signal according to a signal recorded in the layer and outputs the second recording pulse signal to the second laser driving circuit, and includes a first signal recording layer, An optical disc recording / reproducing apparatus characterized in that when the signal recording operation to the second signal recording layer is simultaneously performed, the first laser diode and the second laser diode do not emit light at the recording level simultaneously. When the recording operation on the first signal recording layer by the output signal of the first recording pulse generation circuit is performed at a higher density than the recording operation on the second signal recording layer by the output signal of the second recording pulse generation circuit, 2. The optical disk according to claim 1, wherein an exclusive OR output of the output signal of the first recording pulse generation circuit and the output signal of the second recording pulse generation circuit is supplied to the second laser driving circuit. Recording / playback device. A focus servo circuit that performs a control operation for focusing the laser beam emitted from the first laser diode on the first signal recording layer and a control operation for focusing the laser beam emitted from the second laser diode on the second signal recording layer And a focus control operation for focusing the laser light emitted from the first laser diode on the first signal recording layer when performing the signal recording operation on the first signal recording layer and the second signal recording layer. The optical disk recording / reproducing apparatus according to claim 1, wherein the optical disk recording / reproducing apparatus is performed. A focus servo circuit that performs a control operation for focusing the laser beam emitted from the first laser diode on the first signal recording layer and a control operation for focusing the laser beam emitted from the second laser diode on the second signal recording layer When the focus servo circuit performs a focus control operation for focusing the laser light emitted from the first laser diode on the first signal recording layer, the laser light emitted from the second laser diode is second. 2. The optical disc recording / reproducing apparatus according to claim 1, wherein an optical system of the optical pickup is set so as to focus on the signal recording layer.

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