JP4162391B2 - Optical disc apparatus and arithmetic circuit - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical disk apparatus and an arithmetic circuit using servo means.
[0002]
[Prior art]
In recent years, not only read-only optical discs such as CD-ROMs and DVD-ROMs but also writable optical discs such as CD-R (Recordable) and CD-RW (ReWritable) have become widespread. In these optical discs, laser light mainly from a semiconductor laser is irradiated onto the optical disc surface by an objective lens of an optical pickup, and the reflected light is received by a light receiving element. Based on the detection signal, a tracking error signal, a focus error signal, etc. A servo control signal is generated, and playback / erasing / recording operations are performed while performing servo control of the optical pickup. For this reason, as the light receiving element, a two-divided light receiving element or a four-divided light receiving element is used, and in the case of the three beam method or the like, a plurality of light receiving elements are used to receive each beam.
[0003]
[Problems to be solved by the invention]
At this time, not only the reflected light from the optical disk to be detected but also the diffracted light of the laser may enter the light receiving element directly or reflected from the end face of the optical system. This is called stray light (flare light), and becomes an error signal of the detection signal from the light receiving element, and thus becomes an offset of the servo signal, and its influence needs to be removed.
[0004]
In particular, in a hologram laser or the like in which a part of an optical system is formed in an LD package, which is a light source of an optical disk device, and a light receiving element is also arranged inside the LD package, there is leakage light due to internal irregular reflection or diffraction of the optical system. It becomes a significant problem because it gets in to a certain extent. Such hologram lasers have been more common in read-only drives for reasons such as simplification of the optical system and cost performance, but recently they are also used in writable optical disc drives. The need for stray light countermeasures is increasing.
[0005]
Therefore, the present invention appropriately eliminates the influence of offset caused by stray light other than light from the optical disk on a plurality of light receiving elements and other optical system factors other than stray light, and performs appropriate servo control. It is an object of the present invention to provide an optical disk device and an arithmetic circuit that can perform the above-described operations.
[0006]
It is another object of the present invention to provide an optical disc apparatus capable of appropriately removing the influence of offset suitable for reproduction and recording.
[0007]
In addition, the present invention provides an optical disc apparatus capable of appropriately removing the influence of an offset suitable for each, even when using an optical disc having a different waveform pattern of recording laser light, such as a CD-R or CD-RW. The purpose is to do.
[0008]
It is another object of the present invention to provide an optical disc apparatus capable of accurately removing the influence of offset.
[0009]
[Means for Solving the Problems]
An optical disk apparatus according to a first aspect of the present invention includes a laser light source, a plurality of light receiving elements, an optical system that irradiates the optical disk with laser light from the laser light source and causes the plurality of light receiving elements to receive light obtained from the optical disk. An optical pickup, arithmetic means for generating a plurality of control signals based on difference signals and sum signals by arithmetic processing based on the output signals of the plurality of light receiving elements, and changing the offset amount for each arithmetic processing system of each control signal For the control signal based on the difference signal for each control signal and the offset amount changing means to
Oft = α (Oft: offset correction amount, α: constant)
A constant value α satisfying is stored as an adjustment parameter to remove the offset of the control signal, and for the control signal by a sum signal,
Oft = α * P + β
(Oft: offset correction amount, P: laser power, α: constant, β: constant)
A non-volatile memory in which constants α and β satisfying the following equation are stored as adjustment parameters to remove the offset of the control signal;Strategy generating means for generating a recording signal that changes a light emission pattern with time by combining pulse signals having different patterns, and an average value of laser power at the time of recording is estimated from the pulse width of the recording signal, and laser power P is calculated. AskingThe tuning parameters stored in volatile memory andTheCorrection amount calculating means for determining an offset correction amount to be changed by the offset amount changing means based on the laser power P.
[0010]
In the present invention and the following inventions, “light obtained from an optical disk” mainly means reflected light, but may be transmitted light depending on the configuration / system of the optical disk or optical pickup. The “adjustment parameter for removing the offset” mainly means for removing the offset of the control signal generated when light (stray light) other than the light from the optical disc is incident on the light receiving element. The control signal offset may be removed due to other optical system factors other than stray light.
[0011]
Therefore, an offset amount changing means is provided for each control signal processing system so that an offset of a certain control signal does not affect other control signals, and the light receiving element is used in the difference signal system and the sum signal system. Since the degree of influence of stray light, etc. in the case of canceling out and acting in an additive manner, different adjustment parameters for the difference signal system and the sum signal system are stored in the nonvolatile memory in advance, and the offset correction amount Since it is used for the calculation, it is possible to perform appropriate servo control in which the influence of stray light or the like is removed for each control signal.Further, by obtaining the average laser power in consideration of the recording strategy, the influence of stray light can be accurately removed and stable servo control can be performed.
[0012]
Invention of Claim 2The optical disk apparatus includes an optical pickup having a laser light source, a plurality of light receiving elements, and an optical system that irradiates the optical disk with laser light from the laser light source and causes the plurality of light receiving elements to receive light obtained from the optical disk; An arithmetic means for generating a plurality of control signals based on difference signals and sum signals by arithmetic processing based on output signals of the plurality of light receiving elements, and an offset amount changing means for changing an offset amount for each arithmetic processing system of each control signal; For each control signal, for the control signal by the difference signal,
O ft = Α (O ft : A constant value α satisfying offset correction amount, α: constant) is stored as an adjustment parameter for removing the offset of the control signal, and for the control signal by the sum signal,
O ft = Α * P + β
(O ft : Non-volatile memory in which constants α and β satisfying the arithmetic expression: offset correction amount, P: laser power, α: constant, β: constant) are stored as adjustment parameters to remove the offset of the control signal, and the pattern Combining different pulse signals, a light emission pattern generating means for generating a recording signal for changing the light emission pattern over time, a smoothing means for smoothing the recording signal, and a signal level smoothed by the smoothing means. A detecting means for detecting, an average value of laser power is estimated from the signal level detected by the detecting means to obtain a laser power P, and the adjustment parameter stored in the volatile memory and the laser power P are Correction amount calculating means for determining an offset correction amount to be changed by the offset amount changing means.
[0013]
In the present invention and the following invention, “at the time of recording” means a concept including the time of erasure when rewritable.
[0014]
Therefore,In order to prevent an offset of a certain control signal from affecting other control signals, an offset amount changing means is provided for each control signal calculation processing system, and in the difference signal system and the sum signal system, stray light in the light receiving element is provided. Since there are differences such as the degree of influence such as canceling and additive effects, different adjustment parameters for the difference signal system and the sum signal system are stored in the nonvolatile memory in advance to calculate the offset correction amount. Since it is used, it is possible to perform appropriate servo control in which the influence of stray light or the like is removed for each control signal. Also, by calculating the average value of the laser power by averaging the actual pulse signals during recording and detecting the signal level, the calculation for obtaining the average laser power from the recording strategy can be omitted, reducing the burden on the firmware. While accurately removing the effects of stray light,Stable servo control can be performed.
[0015]
Invention of Claim 3The calculation circuit includes an optical pickup having a laser light source, a plurality of light receiving elements, and an optical system that irradiates the optical disk with laser light from the laser light source and causes the plurality of light receiving elements to receive light obtained from the optical disk. An arithmetic circuit that generates a plurality of control signals based on difference signals and sum signals by arithmetic processing based on output signals of the plurality of light receiving elements, and sets an offset amount for each arithmetic processing system of the control signals. An offset amount changing circuit to change, the offset amount changing circuit is stored in a nonvolatile memory as an adjustment parameter for removing the offset of the control signal for the control signal by the difference signal,
O ft = Α (O ft : Offset correction amount, α: Constant)
Laser power P determined by estimating an average value of laser power at the time of recording from a pulse width of a recording signal in which a constant value α and a pulse signal having a different pattern are combined and a light emission pattern changes with time, The offset amount is changed by an offset amount determined based on the control signal, and the control signal based on the sum signal is stored in a nonvolatile memory as an adjustment parameter for removing the offset of the control signal.
O ft = Α * P + β
(O ft : Offset correction amount, P: Laser power, α: Constant, β: Constant) The offset amount is changed by the amount of offset determined based on the constants α and β satisfying the arithmetic expression and the laser power P. To be characterized byTo do.
[0016]
Therefore,In order to prevent an offset of a certain control signal from affecting other control signals, an offset amount changing means is provided for each control signal calculation processing system, and the difference signal system and the sum signal system have stray light in the light receiving element. Since there are differences such as the degree of influence such as canceling and additive effects, different adjustment parameters for the difference signal system and the sum signal system are stored in the nonvolatile memory in advance to calculate the offset correction amount. By using this arithmetic circuit, it is possible to perform proper servo control that eliminates the effects of stray light etc. for each control signal.The
[0017]
Invention of Claim 4The calculation circuit includes an optical pickup having a laser light source, a plurality of light receiving elements, and an optical system that irradiates the optical disk with laser light from the laser light source and causes the plurality of light receiving elements to receive light obtained from the optical disk. An arithmetic circuit that generates a plurality of control signals based on difference signals and sum signals by arithmetic processing based on output signals of the plurality of light receiving elements, and sets an offset amount for each arithmetic processing system of the control signals. An offset amount changing circuit to change, the offset amount changing circuit is stored in a nonvolatile memory as an adjustment parameter for removing the offset of the control signal for the control signal by the difference signal,
O ft = Α (O ft : Offset correction amount, α: Constant)
Is determined by estimating the average value of the laser power at the time of recording from the signal level detected by smoothing the recording signal in which the light emission pattern changes with time by combining a constant value α and a pulse signal having a different pattern. The offset amount is changed by an offset amount determined based on the laser power P, and the control signal based on the sum signal is stored in a nonvolatile memory as an adjustment parameter for removing the offset of the control signal. Saved,
O ft = Α * P + β
(O ft : Offset correction amount, P: Laser power, α: Constant, β: Constant) The offset amount is changed by the amount of offset determined based on the constants α and β satisfying the arithmetic expression and the laser power P. To be characterized byTo do.
[0018]
Therefore,In order to prevent an offset of a certain control signal from affecting other control signals, an offset amount changing means is provided for each control signal calculation processing system, and in the difference signal system and the sum signal system, stray light in the light receiving element is provided. Since there are differences such as the degree of influence such as canceling and additive effects, different adjustment parameters for the difference signal system and the sum signal system are stored in the nonvolatile memory in advance to calculate the offset correction amount. Since it is used, by installing the arithmetic circuit, it is possible to remove the effects of stray light etc. for each control signal.Servo control can be performed.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
A first embodiment of the present invention will be described with reference to FIGS. The present embodiment shows an application example to an optical disc apparatus compatible with CD-R / RW (CD-Recorable / Rewritable) which is a recordable optical disc.
[0024]
FIG. 1 is a block diagram showing an example of the configuration of an optical disk apparatus according to the present embodiment, particularly its drive system. First, a spindle motor 2 for rotating the optical disk 1 is provided. The spindle motor 2 is controlled to be a constant linear velocity (CLV) method or a constant rotation speed (CAV) method under the control of the motor driver 3 and the servo means 4.
[0025]
As will be described in detail later, the optical pickup 5 that irradiates the optical disc 1 with laser light includes a light source using a semiconductor laser having a wavelength of 780 nm, an optical system such as an objective lens, a focus actuator (the focus of the laser light is recorded on the optical disc 1). A mechanism for moving the position of the objective lens in a direction perpendicular to the recording surface so as to match the surface), a track actuator (a mechanism for moving the objective lens in the radial direction of the optical disc 1 so that the focal point of the laser beam traces the track), PD, etc. Built-in light receiving element, position sensor and the like. The laser beam emitted from the semiconductor laser is focused on the recording surface of the optical disc 1 by the objective lens, and each signal from the light receiving element that receives the reflected light from the optical disc 1 is processed in the RF amplifier 6 to read out the signal (RF Various control signals such as a focus error signal FE and a track error signal TE are generated. Based on these control signals, the actuator is controlled by servo means 4 such as focus servo and track servo, whereby information recorded on the optical disc 1 is reproduced or recorded on the optical disc 1.
[0026]
In the case of CD data reproduction, the reproduction signal obtained by the optical pickup 5 is arithmetically amplified and binarized (digitized) by the RF amplifier 6, and then input to the CD decoder 7 and demodulated by EFM (Eight to Fourteen Modulation). . After that, deinterleaving (reordering) and error correction processing are performed on the EFM demodulated data, and the data after deinterleaving and error correction processing is input to the CD-ROM decoder 8 for data reliability. Error correction processing is performed to improve the performance.
[0027]
Thereafter, the data processed by the CD-ROM decoder 8 is temporarily stored in the buffer RAM 10 by the buffer manager 9, and when it is prepared as sector data, it is sent to a host computer (not shown) via the host interface 11 such as ATAPI or SCSI. Sent at once.
[0028]
In the case of music data, the output data from the CD decoder 7 is input to the D / A converter 18 and an analog audio signal is taken out.
[0029]
On the other hand, when CD data is recorded, data sent from the host computer side via the host interface 11 such as ATAPI or SCSI is temporarily stored in the buffer RAM 10 by the buffer manager 9, and a certain amount of data has accumulated in the buffer RAM 10. Writing is started via the CD-ROM encoder 13, the CD encoder 14, and the LD driver 15. Here, prior to this writing, the spot of the laser beam must be positioned at the writing start position. This writing start position is obtained by a wobble signal that is preliminarily recorded on the optical disk 1 by meandering of the track. This wobble signal includes absolute time information called ATIP (Absolute Time In Pregroove), and the ATIP decoder 12 extracts this information. The synchronization signal generated by the ATIP decoder 12 is input to the CD encoder 14 so that data can be written at an accurate position.
[0030]
The data in the buffer RAM 10 is subjected to error correction code addition and interleaving, and then EFM-modulated and recorded on the optical disc 1 via the LD driver 15 and the optical pickup 5.
[0031]
Such an optical desk apparatus includes a system controller 16 having a microcomputer configuration including a CPU, a ROM, and a RAM for controlling the operation of each unit as described above and executing functions of means described later. A memory 17 is connected to the system controller 16. The memory 17 includes a nonvolatile memory such as a flash ROM.
[0032]
In the configuration shown in FIG. 1, the RF amplifier 6 and the LD driver 15 as arithmetic means or arithmetic circuits are configured as an LSI as an analog chip, and include servo means 4, CD decoder 7, CD-ROM decoder 8, buffer manager 9, The ATIP decoder 12, the CD-ROM encoder 13, the CD encoder 14 and the system controller 16 are configured as an LSI as a digital chip.
[0033]
Next, a basic configuration example of the optical pickup 5 will be described with reference to FIG. The optical pickup 5 used in the present embodiment is parallelized with a semiconductor laser unit 21 in which a light source and a light receiving element are integrated, a coupling lens 22 that collimates a laser beam emitted from the semiconductor laser unit 21. A deflection prism 23 that deflects the laser beam toward the optical disc 1 side, a wave plate 24, and an objective lens 25 that focuses the laser beam on the recording surface of the optical disc 1 are provided. Since the semiconductor laser unit 21 is also integrated with the light receiving element, the reflected light reflected by the optical disk 1 is also configured to return into the semiconductor laser unit 21 via the objective lens 25 and the like. A front light receiving element 26 for monitoring the light quantity of the semiconductor laser in the semiconductor laser unit 21 is also provided.
[0034]
FIG. 3 shows a configuration example of the semiconductor laser unit 21. The semiconductor laser unit 21 is configured to use a hologram laser to separate outgoing light and return light (reflected light). That is, the semiconductor laser unit 21 includes a semiconductor laser 32 as a light source and a light receiving element 33 in a unit housing 31 that are positioned at predetermined positions, and returns light to the light receiving element 33 at a position on the emission side of the semiconductor laser 32. A hologram element 34 is attached to the incident side position.
[0035]
As a method for detecting the focus error signal FE, an astigmatism method, a knife edge method, or the like is generally used, and the astigmatism method is used in the present embodiment. The track error signal TE is detected by several methods such as a push-pull method, a DPD (Differential Phase Detection) method, and a three-beam method. In the present embodiment, A DPP ((Differential Push-Pull) method using three beams is used. For this reason, the laser beam emitted from the semiconductor laser 32 is divided into a main beam and two sub-beams by a diffraction grating (not shown). 2, the optical system 1 shown in Fig. 2 irradiates the optical disc 1. Reflected light components of the three beams from the optical disc 1 are diffracted by the hologram element 34, and incident light (semiconductor laser 32). And the light is condensed on the light receiving element 33.
[0036]
Referring to FIG. 4, the light receiving element 33 is divided into four light receiving areas A, B, C, and D for receiving a reflected light component related to the main beam M, and a reflection related to one sub beam S1. The light receiving regions E1 and E2 that are divided into two in the tracking direction for receiving the light component and function as light receiving elements, and the light receiving regions that are divided into two in the tracking direction for receiving the reflected light component related to the other sub-beam S2 It has light receiving areas F1 and F2 that function.
[0037]
Here, with reference to FIG. 4, the calculation of the relationship between the main beam M, the sub beams S1 and S2, the track error signal TE, and the like will be described. First, the two sub beams S1 and S2 are arranged so as to be shifted from the main beam M by 1/2 track.
[0038]
Thereby, each control signal is obtained, for example, by performing the following known calculation.
[0039]
Track error signal TE = C−D−K ((E + G) − (F + H)) (1)
Focus error signal FE = A-B (2)
Sum signal SUM = C + D ………………………… (3)
Track cross signal TC = C + D-K ((E + G) + (F + H)) (4)
Here, K is a constant representing the ratio between the main beam M and the sub beams S1 and S2.
[0040]
That is, the track error signal TE is a differential push-pull signal obtained by taking the difference between the push-pull of the main beam M and the push-pull of the sub beams S1 and S2. By using such a differential push-pull signal, the offset between the main beam M and the sub-beams S1 and S2 is canceled, so that there is an advantage that the characteristics with respect to disc tilt and lens shift are strong. The focus error signal FE is obtained by the astigmatism method using the received light amounts of the four divided areas A, B, C, and D for the main beam M. These track error signal TE and focus error signal FE are control signals based on difference signals in the control signal. On the other hand, the track cross signal TC is also referred to as a ripple signal of the reproduction signal RF, and is a signal mainly used for counting the number of tracks straddling when seeking the carriage. The track cross signal TC becomes a control signal based on the sum signal in the control signal together with the sum signal SUM.
[0041]
Here, not only the reflected light from the optical disc 1 but also the diffracted light of the laser may enter the light receiving element 33 directly or reflected from the end face of the optical system. This is called stray light (flare light), and for example, as shown in FIG. In particular, the semiconductor laser unit 21 using a hologram laser as shown in FIG. 3 is problematic because it is easily affected by stray light due to the shape of its optical system.
[0042]
For this reason, in this embodiment, the RF amplifier 6 having the LSI chip configuration is configured such that the offset amount can be changed for each arithmetic processing system of each control signal.
[0043]
FIG. 6 shows a block diagram for generating each control signal of the present embodiment. An arithmetic processing system 41 that generates control signals SUM, TE, FE, and TC based on equations (1) to (4) based on signals obtained from the light receiving element 33 (light receiving areas A to F2) in the optical pickup 5. , 42, 43, 44 are provided. The arithmetic processing system 41 includes a SUM signal arithmetic unit 45 using an operational amplifier or the like, a low-pass filter (LPF) 46, and a voltage variable amplifier (VCA) 47. The arithmetic processing system 42 includes a TE signal arithmetic unit using an operational amplifier or the like. 48, a VCA 49, and a phase compensator 50. The arithmetic processing system 43 is configured by an FE signal calculation unit 51, a VCA 52, and a phase compensator 53 by an operational amplifier, and the arithmetic processing system 44 is a TC signal by an operational amplifier. The calculation unit 54, the VCA 55, and the phase compensator 56 are included. In addition, each signal calculating part 45,48,51,54 is not necessarily provided separately, and is comprised in the form shared suitably.
[0044]
Here, the arithmetic processing system 41 is provided with an offset addition circuit 57 for performing offset adjustment of each VCA 47, 49, 52, 55 after the calculation. Here, an AGC (Auto Gain Control) circuit using a known sum signal SUM is used, and gain adjustment is performed in real time by the AGC circuit so that the signal amplitude of the sum signal SUM becomes the target level SUMx, and the adjustment gain is adjusted. Thus, gain control of the VCAs 49, 52, and 55 of the other arithmetic processing systems 42, 43, and 44 is performed. With only such a basic configuration, the offset of the sum signal SUM affects the other control signals TE, FE, and TC.
[0045]
Therefore, in the present embodiment, as shown in FIG. 5, adders 58, 59, 60, 61 for individually changing and setting the offset amount for each arithmetic processing system 41, 42, 43, 44 are offset. An amount change means or an offset amount change circuit is provided in the preceding stage of each VCA 47, 49, 52, 55, and is configured to be provided with an individual offset amount Ofs.
[0046]
In general, in the case of a control signal for a difference signal such as a track error signal TE or a focus error signal FE, if the flare incident on each light receiving region of the divided structure is equal in the light receiving element 33, the influence is small. It hardly depends on the laser power. For example, FIG. 7 shows an offset cancellation amount ΔTEOFS applied to the adder 59 for the track error signal TE. However, in the case of a sum signal control signal such as the sum signal SUM or the track cross signal TC, the influence of stray light is significant, and the offset increases in proportion to the laser power. For example, FIG. 8 shows an offset cancellation amount ΔSUMOFS applied to the adder 58 for the sum signal SUM during reproduction, and FIG. 9 shows an offset cancellation amount ΔSUMOFS applied to the adder 58 for the sum signal SUM during recording on a CD-RW disc. Is shown.
[0047]
Here, since the influence of the stray light is different for each optical pickup 5 and must be adjusted at the time of manufacture for each optical disk device, in this embodiment, the sum signal control signal of the sum signal SUM and the track cross signal TC is used. As the offset correction amount Ofs for
Ofs = α * P + β …………………………………… (5)
(Ofs: offset correction amount, P: laser power, α: constant, β: constant)
Constants α and β satisfying the following formula are stored in advance as adjustment parameters in a nonvolatile memory such as a flash ROM included in the memory 17 for each optical disk device, and a difference signal system of the track error signal TE and the focus error signal FE is stored. For the control signal of
Ofs = α …………………………………… (6)
A constant value α satisfying the above condition is stored in advance as an adjustment parameter in a nonvolatile memory such as a flash ROM included in the memory 17 for each optical disk device.
[0048]
In addition, known high-frequency superposition (HFM) is performed on the semiconductor laser in order to reduce the noise of the semiconductor laser itself. However, an offset (HF offset) may be placed on the signal due to this influence. This HF offset is also corrected.
[0049]
Actually, since the offset of the circuit itself also exists, the circuit offset Ofs_cir is first adjusted at the time of starting the optical disk device, and the system controller 16 functions as a correction amount calculating means, thereby adding the stray light offset Ofs_flar to the nonvolatile memory. Calculate using the saved adjustment parameters and add as follows:
Ofset = Ofs_cir + Ofs_flar (7)
The obtained offset correction amount is set individually for each adder 58, 59, 60, 61.
[0050]
By the way, the laser power used and the light emission waveform are different between when the optical disc 1 is reproduced and when it is recorded. When the output gain of the light receiving element 33 is switched between reproduction and recording, or when the servo signal detection during recording is performed by a known average value method, the influence of stray light differs between reproduction and recording. Therefore, it is preferable that the adjustment parameters are stored separately in the nonvolatile memory as different values for reproduction and recording.
[0051]
Therefore, according to the present embodiment, the offset amount changing means is individually provided for each arithmetic processing system 41, 42, 43, 44 of each control signal so that an offset of a certain control signal does not affect other control signals. (Adders 58, 59, 60, 61) are provided, and the difference signal system and the sum signal system are different in that the degree of the influence of stray light or the like in the light receiving element 33 is counteracting or additive Since adjustment parameters that differ between the difference signal system and the sum signal system are stored in the nonvolatile memory in advance and used to calculate the offset correction amount, an appropriate servo that eliminates the effects of stray light etc. for each control signal Control can be performed. Even when the output gain of the light receiving element 33 is switched between reproduction and recording, or even when the average value servo means is used as the servo means 4 during recording, the adjustment parameter for recording is used. By storing the values different from the parameters for reproduction, stable servo control can be performed during recording.
[0052]
A second embodiment of the present invention will be described with reference to FIGS. The same parts as those shown in the above-described embodiment are denoted by the same reference numerals, and description thereof is also omitted (the same applies to the following embodiments).
[0053]
In the present embodiment, the value of the adjustment parameter is changed for each type of the optical disk 1 to be loaded and stored in the nonvolatile memory.
[0054]
FIG. 10 shows the light emission waveform (light emission pattern) of the recording laser beam and the pulse signals (EFM1, EFM2) during recording on the CD-R disc. The light emission pattern is created by forming the recording power Pw by the timing pulse by the pulse signal EFM1, and adding the extra power Pex by the pulse signal EFM2. The APC control (Auto Power Control) is applied so that the power Pw and Pex of the light emission pattern can be kept at a constant level by controlling the voltage (actually current) supplied from the external D / A (see FIG. 12). It is done. Note that Pr indicates a reproduction power level.
[0055]
On the other hand, FIG. 11 shows the light emission waveform (light emission pattern) of the recording laser beam and the pulse signals (EFM1, EFM2) during recording on the CD-RW disc. Since a phase change medium is used as the CD-RW, the light emission pattern is a multi-pulse. The timing of the recording power Pw is generated by the pulse signal EFM1, and the erase power Pe is generated by the pulse signal EFM2.
[0056]
Thus, considering the emission laser power at the time of recording from the difference in the emission waveform of the recording laser light between the CD-R disc and the CD-RW disc, the average laser power is greatly different and the reflectance is also greatly different. Often, the gain setting is changed. For this reason, in the present embodiment, adjustment parameters for performing stray light correction are made different for each type of the optical disc 1 and stored in the nonvolatile memory.
[0057]
Therefore, according to the present embodiment, the value of the adjustment parameter is stored in the non-volatile memory for each type of the optical disc 1 having a different light emission pattern, so that an appropriate servo corresponding to the type of each optical disc 1 is stored. Control becomes possible.
[0058]
A third embodiment of the present invention will be described.
[0059]
In general, in order to optimize the recording quality on the optical disc 1, the pulse width called a recording strategy is adjusted with respect to the emission waveform of the recording laser beam. This is to adjust the timing width of the pulse signals EFM1 and EFM2 as described above and the sizes of the laser powers Pw and Pex for each disk vendor and each recording speed so that an optimum recording state can be created. As a result, the average laser power changes, and the influence of stray light cannot be accurately removed.
[0060]
Therefore, in the present embodiment, in calculating the offset correction amount, the system controller 16 calculates the average laser power according to the recording strategy that is the result of optimizing the emission waveform of the recording laser light, and this average laser The offset correction amount Oft is determined with respect to the power.
[0061]
Therefore, according to the present embodiment, the average laser power at the time of recording is estimated from the set value of the recording strategy and the recording laser power, and the offset correction amount is calculated from the value, that is, considering the recording strategy. By obtaining the average laser power, the influence of stray light can be accurately removed and stable servo control can be performed.
[0062]
A fourth embodiment of the present invention will be described with reference to FIG. In the present embodiment, a low-pass filter that smoothes the signal EFM by the pulse signal between the encoder 14 and the system controller 16 that outputs the signal EFM to the optical pickup 5 (LD driver 15) during recording. A smoothing means 71 using (LPF) or the like and an A / D converter 72 as a detecting means for detecting the smoothed signal level are interposed.
[0063]
As a result, the correction amount calculation means by the system controller 16 estimates the average value of the laser power from the signal level detected by the A / D converter 72, and in the RF amplifier 6 according to the estimated average value of the laser power. The offset correction amount Oft applied to each adder 58, 59, 60, 61 is individually determined. That is, since the pulse signal EFM is smoothed by the smoothing means 71 and the signal level is measured by the A / D converter 72, the duty of the recording pulse can be known, so the firmware (F / F) calculates the average laser power from the recording strategy. W) can be reduced, the offset correction amount for stray light can be obtained appropriately from the duty ratio and the recording laser power, the influence of stray light can be accurately removed, and stable servo control can be performed.
[0064]
【The invention's effect】
According to the optical disk apparatus of the first aspect of the present invention, an optical device that irradiates the optical disk with a laser light source, a plurality of light receiving elements, and laser light from the laser light source and causes the plurality of light receiving elements to receive light obtained from the optical disk An optical pickup having a system, computing means for generating a plurality of control signals based on difference signals and sum signals by arithmetic processing based on output signals of the plurality of light receiving elements, and an offset amount for each arithmetic processing system of each control signal For each control signal, the offset amount changing means for changing the control signal by the difference signal,
Oft = α (Oft: offset correction amount, α: constant)
A constant value α satisfying is stored as an adjustment parameter to remove the offset of the control signal, and for the control signal by a sum signal,
Oft = α * P + β
(Oft: offset correction amount, P: laser power, α: constant, β: constant)
A non-volatile memory in which constants α and β satisfying the following equation are stored as adjustment parameters to remove the offset of the control signal;Strategy generating means for generating a recording signal that changes a light emission pattern with time by combining pulse signals having different patterns, and an average value of laser power at the time of recording is estimated from the pulse width of the recording signal, and laser power P is calculated. AskingThe tuning parameters stored in volatile memory andTheCorrection amount calculating means for determining an offset correction amount to be changed by the offset amount changing means based on the laser power P, so that an offset of a certain control signal does not affect other control signals. An offset amount changing unit is provided for each control signal calculation processing system, and the difference signal system and the sum signal system are different in that the degree of the influence of stray light or the like on the light receiving element is counteracting or additive. Therefore, since the adjustment parameters that are different for the difference signal system and the sum signal system are stored in the nonvolatile memory in advance and used to calculate the offset correction amount, it is possible to remove the influence of stray light etc. for each control signal. Servo control can be performed.The correction amount calculation means calculates an average laser power according to a recording strategy that is a result of optimizing the emission waveform of the recording laser beam, and the offset correction amount O is calculated with respect to the average laser power. ft Thus, by obtaining the average laser power in consideration of the recording strategy, it is possible to accurately remove the influence of stray light and perform stable servo control.
[0065]
Invention of Claim 2According to the optical disc apparatus, the optical pickup includes a laser light source, a plurality of light receiving elements, and an optical system that irradiates the optical disk with laser light from the laser light source and causes the plurality of light receiving elements to receive light obtained from the optical disk. And an arithmetic means for generating a plurality of control signals based on difference signals and sum signals by arithmetic processing based on output signals of the plurality of light receiving elements, and an offset amount change for changing the offset amount for each arithmetic processing system of the control signals And for each control signal, for the control signal by the difference signal,
O ft = Α (O ft : Offset correction amount, α: Constant)
A constant value α satisfying is stored as an adjustment parameter to remove the offset of the control signal, and for the control signal by a sum signal,
O ft = Α * P + β
(O ft : Non-volatile memory in which constants α and β satisfying the arithmetic expression: offset correction amount, P: laser power, α: constant, β: constant) are stored as adjustment parameters to remove the offset of the control signal, and the pattern Combining different pulse signals, a light emission pattern generating means for generating a recording signal for changing the light emission pattern over time, a smoothing means for smoothing the recording signal, and a signal level smoothed by the smoothing means. A detecting means for detecting, an average value of laser power is estimated from the signal level detected by the detecting means to obtain a laser power P, and the adjustment parameter stored in the volatile memory and the laser power P are Correction amount calculating means for determining an offset correction amount to be changed by the offset amount changing means based on In order to prevent the signal offset from affecting other control signals, an offset amount changing means is provided for each control signal processing system, and the difference signal system and the sum signal system are affected by stray light in the light receiving element. Since there are differences such as the degree of canceling and acting additively, different adjustment parameters for the difference signal system and the sum signal system are stored in the nonvolatile memory in advance and used for calculating the offset correction amount. Therefore, it is possible to perform proper servo control in which the influence of stray light or the like is removed for each control signal. Also, by calculating the average value of the laser power by averaging the actual pulse signals during recording and detecting the signal level, the calculation for obtaining the average laser power from the recording strategy can be omitted, reducing the burden on the firmware. While accurately removing the effects of stray light,Stable servo control can be performed.
[0066]
Invention of Claim 3According to this arithmetic circuit, the optical pickup includes a laser light source, a plurality of light receiving elements, and an optical system that irradiates the optical disk with laser light from the laser light source and causes the plurality of light receiving elements to receive light obtained from the optical disk. Is an arithmetic circuit that generates a plurality of control signals based on difference signals and sum signals by arithmetic processing based on output signals of the plurality of light receiving elements, and is offset for each arithmetic processing system of the control signals. An offset amount changing circuit for changing an amount, and the offset amount changing circuit is stored in a nonvolatile memory as an adjustment parameter for removing the offset of the control signal for the control signal based on the difference signal,
O ft = Α (O ft : Offset correction amount, α: Constant)
Laser power P determined by estimating an average value of laser power at the time of recording from a pulse width of a recording signal in which a constant value α and a pulse signal having a different pattern are combined and a light emission pattern changes with time, The offset amount is changed by an offset amount determined based on the control signal, and the control signal based on the sum signal is stored in a nonvolatile memory as an adjustment parameter for removing the offset of the control signal.
O ft = Α * P + β
(O ft : Offset correction amount, P: Laser power, α: Constant, β: Constant) The offset amount is changed by the offset amount determined based on the constants α and β satisfying the arithmetic expression and the laser power P. Thus, an offset amount changing means is provided for each arithmetic processing system of each control signal so that an offset of a certain control signal does not affect other control signals, and the difference signal system and the sum signal system Because the degree of influence of stray light on the light receiving element is counterbalance or additive, there is a difference between the difference signal system and the sum signal system. Since it is used for the calculation of the amount, it is possible to perform proper servo control by removing the influence of stray light etc. for each control signal by installing the arithmetic circuit.The
[0067]
Invention of Claim 4According to this arithmetic circuit, the optical pickup includes a laser light source, a plurality of light receiving elements, and an optical system that irradiates the optical disk with laser light from the laser light source and causes the plurality of light receiving elements to receive light obtained from the optical disk. Is an arithmetic circuit that generates a plurality of control signals based on difference signals and sum signals by arithmetic processing based on output signals of the plurality of light receiving elements, and is offset for each arithmetic processing system of the control signals. An offset amount changing circuit for changing an amount, and the offset amount changing circuit is stored in a nonvolatile memory as an adjustment parameter for removing the offset of the control signal for the control signal based on the difference signal,
O ft = Α (O ft : Offset correction amount, α: Constant)
Is determined by estimating the average value of the laser power at the time of recording from the signal level detected by smoothing the recording signal in which the light emission pattern changes with time by combining a constant value α and a pulse signal having a different pattern. The offset amount is changed by an offset amount determined based on the laser power P, and the control signal based on the sum signal is stored in a nonvolatile memory as an adjustment parameter for removing the offset of the control signal. Saved,
O ft = Α * P + β
(O ft : Offset correction amount, P: Laser power, α: Constant, β: Constant) The offset amount is changed by the offset amount determined based on the constants α and β satisfying the arithmetic expression and the laser power P.by doing,In order to prevent an offset of a certain control signal from affecting other control signals, an offset amount changing means is provided for each control signal calculation processing system, and in the difference signal system and the sum signal system, stray light in the light receiving element is provided. Since there are differences such as the degree of influence such as canceling and additive effects, different adjustment parameters for the difference signal system and the sum signal system are stored in the nonvolatile memory in advance to calculate the offset correction amount. Since it is used, by installing the arithmetic circuit, it is possible to remove the effects of stray light etc. for each control signal.Servo control can be performed.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration example of a CD-R / RW drive apparatus as a first embodiment of the present invention.
FIG. 2 is a configuration diagram of an optical system showing the optical pickup.
FIG. 3 is a schematic cross-sectional view showing a configuration example of the semiconductor laser unit.
FIG. 4 is an explanatory diagram showing a DPP method using three beams.
FIG. 5 is an explanatory diagram showing an offset state.
FIG. 6 is a circuit diagram illustrating a configuration example of an RF amplifier.
FIG. 7 is a characteristic diagram showing a correction amount of a difference signal (TE signal).
FIG. 8 is a characteristic diagram showing the correction amount of the sum signal during reproduction.
FIG. 9 is a characteristic diagram showing the correction amount of the sum signal during recording.
FIG. 10 is a waveform diagram showing an example of a light emission waveform at the time of CD-R recording according to the second embodiment of the present invention.
FIG. 11 is a waveform diagram showing an example of a light emission waveform during CD-RW recording.
FIG. 12 is a block diagram illustrating a configuration example of a part of a CD-R / RW drive device according to a third embodiment of the present invention;
[Explanation of symbols]
1 Optical disc
5 Optical pickup
6 Calculation means, calculation circuit
16 Correction amount calculation means
17 Nonvolatile memory
32 Laser light source
41-44 processing system
58-61 Offset amount changing means, offset amount changing circuit
71 Smoothing means
72 Detection means
A ~ F2 Light receiving element
TE, FE, SUM, TC control signal

Claims (4)

An optical pickup comprising: a laser light source; a plurality of light receiving elements; and an optical system that irradiates the optical disk with laser light from the laser light source and causes the plurality of light receiving elements to receive light obtained from the optical disk;
Arithmetic means for generating a plurality of control signals by difference signals and sum signals by arithmetic processing based on output signals of the plurality of light receiving elements;
Offset amount changing means for changing the offset amount for each arithmetic processing system of each control signal;
For each control signal, for the control signal by the difference signal,
Oft = α (Oft: offset correction amount, α: constant)
A constant value α satisfying is stored as an adjustment parameter to remove the offset of the control signal, and for the control signal by a sum signal,
Oft = α * P + β
(Oft: offset correction amount, P: laser power, α: constant, β: constant)
A non-volatile memory in which constants α and β satisfying the following equation are stored as adjustment parameters to remove the offset of the control signal;
A strategy generating means for generating a recording signal for changing a light emission pattern with time by combining pulse signals having different patterns;
An average value of the laser power at the time of recording is estimated from the pulse width of the recording signal to obtain a laser power P, and the offset amount changing means is based on the adjustment parameter stored in the volatile memory and the laser power P. An optical disc apparatus comprising: correction amount calculation means for determining an offset correction amount to be changed. An optical pickup comprising: a laser light source; a plurality of light receiving elements; and an optical system that irradiates the optical disk with laser light from the laser light source and causes the plurality of light receiving elements to receive light obtained from the optical disk;
Arithmetic means for generating a plurality of control signals by difference signals and sum signals by arithmetic processing based on output signals of the plurality of light receiving elements;
Offset amount changing means for changing the offset amount for each arithmetic processing system of each control signal;
For each control signal, for the control signal by the difference signal,
O ft = α (O ft : offset correction amount, α: constant)
A constant value α satisfying is stored as an adjustment parameter to remove the offset of the control signal, and for the control signal by a sum signal,
O ft = α * P + β
(O ft : offset correction amount, P: laser power, α: constant, β: constant)
A non-volatile memory in which constants α and β satisfying the following equation are stored as adjustment parameters to remove the offset of the control signal;
A light emission pattern generating means for generating a recording signal for changing a light emission pattern in time by combining pulse signals having different patterns;
Smoothing means for smoothing the recording signal;
Detecting means for detecting the signal level smoothed by the smoothing means;
An average value of laser power is estimated from the signal level detected by the detection means to obtain a laser power P, and the offset amount changing means is based on the adjustment parameter stored in the volatile memory and the laser power P. An optical disc apparatus comprising: a correction amount calculating means for determining an offset correction amount to be changed by the step . Connected to the output side of an optical pickup having a laser light source, a plurality of light receiving elements, and an optical system that irradiates the optical disk with laser light from the laser light source and causes the plurality of light receiving elements to receive light obtained from the optical disk; An arithmetic circuit that generates a plurality of control signals based on difference signals and sum signals by arithmetic processing based on output signals of the plurality of light receiving elements,
  An offset amount changing circuit for changing an offset amount for each arithmetic processing system of each control signal;
  The offset amount changing circuit includes:
For the control signal based on the difference signal, the adjustment signal for removing the offset of the control signal is stored in the nonvolatile memory.
O ft = Α (O ft : Offset correction amount, α: Constant)
And a constant value α
  It was determined based on the laser power P determined by estimating the average value of the laser power at the time of recording from the pulse width of the recording signal in which the pulse signals having different patterns are combined and the light emission pattern changes with time Change the offset amount by the offset amount,
  For the control signal by the sum signal, stored in the nonvolatile memory as an adjustment parameter for removing the offset of the control signal,
O ft = Α * P + β
(O ft : Offset correction amount, P: Laser power, α: Constant, β: Constant)
Constants α and β satisfying the following equation,
  An arithmetic circuit that changes the offset amount by an offset amount determined based on the laser power P. Connected to the output side of an optical pickup having a laser light source, a plurality of light receiving elements, and an optical system that irradiates the optical disk with laser light from the laser light source and causes the plurality of light receiving elements to receive light obtained from the optical disk; An arithmetic circuit that generates a plurality of control signals based on difference signals and sum signals by arithmetic processing based on output signals of the plurality of light receiving elements,
  An offset amount changing circuit for changing an offset amount for each arithmetic processing system of each control signal;
  The offset amount changing circuit includes:
For the control signal based on the difference signal, the adjustment signal for removing the offset of the control signal is stored in the nonvolatile memory.
O ft = Α (O ft : Offset correction amount, α: Constant)
And a constant value α
  Laser power P determined by estimating an average value of laser power at the time of recording from a signal level detected by smoothing a recording signal in which pulse signals having different patterns are combined and a light emission pattern changes with time The offset amount is changed by an offset amount determined based on
  For the control signal by the sum signal, stored in the nonvolatile memory as an adjustment parameter for removing the offset of the control signal,
O ft = Α * P + β
(O ft : Offset correction amount, P: Laser power, α: Constant, β: Constant)
Constants α and β satisfying the following equation,
  An arithmetic circuit that changes the offset amount by an offset amount determined based on the laser power P.

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