JP4434018B2 - Optical disk device - Google Patents

Description

  The present invention relates to an optical disc apparatus, and more particularly to data recording or reproduction for a multilayer optical disc.

  Conventionally, a multilayer optical disc has been proposed in which a plurality of recording layers are stacked to increase the recording capacity. In a multilayer optical disc, when the first recording layer and the second recording layer are formed from the laser light irradiation surface side, data recording / reproduction is usually first performed on the first recording layer, and then data recording / reproduction is performed on the second recording layer. I do. When recording / reproducing data with respect to the second recording layer, the laser light focus surface is shifted from the first recording layer to the second recording layer (hereinafter, this is referred to as a laser light jump as appropriate). It is necessary to acquire the address information of the second recording layer while controlling the on-track state in the second recording layer. Since different addresses are assigned to the first recording layer and the second recording layer, it is verified that the laser beam has jumped from the first recording layer to the second recording layer by acquiring the address information of the second recording layer. Can do. In order to acquire address information, tracking servo is applied in the second recording layer, and a PLL necessary for address demodulation is also required. In general, in multilayer optical discs, servo parameters different from the optimum tracking servo parameters in the first recording layer are used in the second recording layer due to problems such as interlayer crosstalk, optical disc shaping, and laser light refraction by the interlayer transparent film. Must be set. However, after jumping from the first recording layer to the second recording layer, if the servo adjustment was performed again from the beginning in the second recording layer, for example, jumping from the first recording layer to the second recording layer during continuous reading of data When data reading is interrupted each time the data stored in the buffer memory is transferred to the host, problems such as image interruption (when the read data is image data) may occur.

  Therefore, when the servo adjustment is not performed again from the beginning, a difference in servo parameters for each layer is stored in advance as a correction value in a memory or the like, and the first recording layer is jumped from the first recording layer to the second recording layer. It is conceivable to apply the tracking servo of the second recording layer simply and quickly by correcting the servo parameter in the above with the correction value to obtain the servo parameter for the second recording layer.

  However, when jumping from the first recording layer to the second recording layer and returning to the first recording layer without being able to focus on the second recording layer, the microcomputer of the device (drive) moves to the second recording layer. Since the servo parameter is corrected as if it has already jumped, there is a possibility that tracking may be lost or an oscillation phenomenon may occur.

  The following patent document describes a technique for determining the number of recording surfaces of the recording surface of the multilayer optical disc. Means for generating / detecting a first focus error signal having a focus detection range in the vicinity of a single recording surface, and means for generating / detecting a second focus error signal having a wide focus detection range over the entire recording surface; When a first focus error signal is detected on each recording surface, a reference value that can be associated with a layer number from the second focus error signal is stored in advance, and the reference value is detected for each recording surface. It is described that the recording surface of a multilayer optical disc is discriminated by comparing the measured value of the two focus error signal.

Japanese Patent Laid-Open No. 11-96568

  In the above prior art, since it is possible to determine the number of layers of the multilayer optical disc that the laser beam jumps to, the target jump destination is the second recording layer as described above. Although it is possible to cope with the case of returning to the first recording layer, a focus error signal is used to determine the recording surface of the multilayer optical disc, and the tracking servo must be adjusted separately.

  An object of the present invention is to determine a recording layer at a jump destination by using a tracking error signal directly connected to a tracking servo, and thereby perform recording / reproduction of data by quickly applying the tracking servo in the recording layer at the jump destination. An object of the present invention is to provide an apparatus capable of performing the above.

The present invention relates to an optical disc apparatus for recording or reproducing data on a multilayer optical disc having at least a first recording layer and a second recording layer, and means for irradiating the multilayer optical disc with laser light; Means for shifting the focus surface from the first recording layer to the second recording layer, and canceling the tracking servo control when shifting from the first recording layer to the second recording layer; A means for detecting, a means for detecting at least one of an amplitude value or an offset of the detected tracking error signal, and when the second recording layer is focused while maintaining the servo parameters for the first recording layer amplitude value or stores the second recording layer-specific amplitude or offset is the offset of the resultant tracking error signal And the detected amplitude value or offset are compared with the amplitude value or offset unique to the second recording layer, and when both coincide, it is determined that the focus surface of the laser beam has shifted to the second recording layer. Then, the setting of the tracking servo parameter is switched from the tracking servo parameter for the first recording layer to the tracking servo parameter for the second recording layer, and when the two do not match, the focus surface of the laser beam is the second recording layer And determining that the tracking servo parameter is not shifted to the tracking servo parameter for the second recording layer and switching the tracking servo parameter to the tracking servo parameter for the second recording layer.

  According to the present invention, it can be easily determined whether or not the first recording layer has shifted to the second recording layer. Thereby, it is possible to prevent the servo parameter for the second recording layer from being set erroneously even though the transition to the second recording layer has not been made.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 shows the overall configuration of an optical disc apparatus according to the present embodiment. An optical disk 10 such as a DVD-R / -RW, + R / + RW, or RAM is rotated by a spindle motor (SPM) 12. The optical disk 10 has a multilayer structure and has a first recording layer and a second recording layer. In the present embodiment, the recording layer on the front side when viewed from the laser beam is referred to as a first recording layer, and the recording layer on the back side is referred to as a second recording layer. The spindle motor SPM 12 is driven by a driver 14, and the driver 14 is servo-controlled by a servo processor 30 so as to have a desired rotation speed.

  The optical pickup 16 includes a laser diode (LD) for irradiating the optical disk 10 with laser light and a photodetector (PD) that receives reflected light from the optical disk 10 and converts it into an electrical signal, and is disposed opposite to the optical disk 10. . The optical pickup 16 is driven in the radial direction of the optical disk 10 by a thread motor 18, and the thread motor 18 is driven by a driver 20. The driver 20 is servo-controlled by the servo processor 30 similarly to the driver 14. The LD of the optical pickup 16 is driven by a driver 22, and the driver 22 is controlled by an auto power control circuit (APC) 24 so that the drive current becomes a desired value. The APC 24 controls the drive current of the driver 22 so that the optimum recording power selected by OPC (Optimum Power Control) executed in the test area (PCA) of the optical disc 10 is obtained. The OPC is a process of recording test data on the PCA of the optical disc 10 by changing the recording power in a plurality of stages, reproducing the test data, evaluating the signal quality, and selecting a recording power that can obtain a desired signal quality. It is. For the signal quality, β value, γ value, modulation factor, jitter, etc. are used. When the recording layer of the optical disc 10 is composed of the first layer and the second layer, OPC is executed for each recording layer. However, regarding the second layer on the back side, different recording powers are set depending on whether the first layer is unrecorded or recorded.

  When data recorded on the optical disk 10 is reproduced, a laser beam of reproduction power is irradiated from the LD of the optical pickup 16, and the reflected light is converted into an electric signal by the PD and output. A reproduction signal from the optical pickup 16 is supplied to the RF circuit 26. The RF circuit 26 generates a focus error signal and a tracking error signal from the reproduction signal and supplies them to the servo processor 30. The servo processor 30 servo-controls the optical pickup 16 based on these error signals, and maintains the optical pickup 16 in an on-focus state and an on-track state. Further, the RF circuit 26 supplies an address signal included in the reproduction signal to the address decoding circuit 28. The address decoding circuit 28 demodulates the address data of the optical disk 10 from the address signal and supplies it to the servo processor 30 and the system controller 32. Further, the RF circuit 26 supplies the reproduction RF signal to the binarization circuit 34. The binarization circuit 34 binarizes the reproduction signal and supplies the obtained 8-16 modulation signal to the encoding / decoding circuit 36. In the encode / decode circuit 36, the binarized signal is demodulated and error-corrected by 8-16 to obtain reproduction data, and the reproduction data is output to a host device such as a personal computer via the interface I / F 40. When the reproduction data is output to the host device, the encoding / decoding circuit 36 temporarily stores the reproduction data in the buffer memory 38 and outputs it.

  When recording data on the optical disk 10, data to be recorded from the host device is supplied to the encode / decode circuit 36 via the interface I / F 40. The encode / decode circuit 36 stores data to be recorded in the buffer memory 38, encodes the data to be recorded, and supplies the data to the write strategy circuit 42 as 8-16 modulation data. The write strategy circuit 42 converts the modulation data into a multi-pulse (pulse train) according to a predetermined recording strategy, and supplies it to the driver 22 as recording data. The recording strategy is composed of, for example, the pulse width of the first pulse, the pulse width of the subsequent pulse, and the pulse duty in the multi-pulse. Since the recording strategy affects the recording quality, it is usually fixed to a certain optimum strategy. A recording strategy may be set at the time of OPC. The laser light whose power is modulated by the recording data is irradiated from the LD of the optical pickup 16 and the data is recorded on the optical disk 10. The data consists of the mark portion formed by irradiating the recording power laser beam and the length of the space portion where the laser light other than the recording power (reproduction power, zero power or erase power) is irradiated, that is, the mark This is a mark edge method in which recording is performed according to the edge positions of the front end and the rear end. After recording the data, the optical pickup 16 reproduces the recorded data by irradiating a laser beam with a reproduction power, and supplies it to the RF circuit 26. The RF circuit 26 supplies the reproduction signal to the binarization circuit 34, and the binarized 8-16 modulated data is supplied to the encode / decode circuit 36. The encode / decode circuit 36 decodes the 8-16 modulation data, and performs a replacement process when the data cannot be normally decoded. Specifically, the recorded data stored in the buffer memory 38 is recorded in the replacement area.

  When recording / reproducing data, the system controller 32 first records / reproduces data on the first recording layer, and then records / reproduces data on the second recording layer. Since the optimum servo parameters differ between the first recording layer and the second recording layer, the optimum servo parameters for each layer are stored in the memory in advance. A servo parameter for the first recording layer is set during recording / reproduction of the first recording layer, and a servo parameter for the second recording layer is set during recording / reproduction of the second recording layer. For example, the servo parameters of each layer can be based on the value of the first recording layer, and the second recording layer can be a difference value or a correction value from the reference value. The servo parameters are specifically tracking servo gain and tracking offset. When the gain and offset in the first recording layer are G1 and OF1, respectively, and the gain and offset in the second recording layer are G2 and OF2, respectively, when jumping from the first recording layer to the second recording layer, the parameters of the tracking servo are also By switching from G1 to G2 and from OF1 to OF2, tracking servo can be quickly applied to demodulate the address in the second recording layer and data can be recorded / reproduced. However, when jumping from the first recording layer to the second recording layer as described above and returning to the first recording layer without focusing to the second recording layer, the original servo parameters are G1 and OF1. Nevertheless, the system controller 32 erroneously sets G2 and OF2.

  Therefore, in this embodiment, when the system controller 32 jumps from the first recording layer to the second recording layer, the system controller 32 jumps with the tracking servo turned OFF, and a tracking error signal after the jump (tracking error signal in an open loop). Is detected and compared with the tracking error signal in the first recording layer.

  FIG. 2 shows a state of jumping from the first recording layer to the second recording layer, and FIG. 3 shows that the servo parameters (gain and offset) of the first recording layer are maintained as they are, and the first recording layer to the second recording layer. The tracking error signal waveform change when jumping to is shown. FIG. 3A shows the waveform of the first recording layer, and FIG. 3B shows the waveform of the second recording layer. Both are signal waveforms when the tracking servo is OFF. The signal waveform of the second recording layer is different from the signal waveform of the first recording layer, the amplitude value Vpp of the signal waveform is different, and the signal waveform of the second recording layer has a deviation in the amplitude balance (offset) ) In the present embodiment, by utilizing the difference in the tracking error signal waveform between the first recording layer and the second recording layer, the signal waveform changes as shown in FIG. 3 when jumping from the first recording layer to the second recording layer. It is determined whether or not it is detected, and when a change in the signal waveform is detected, it is determined that the jump has surely been made to the second recording layer, and then the servo parameter is set to the parameter for the second recording layer.

  FIG. 4 schematically shows determination parameters and servo parameters for each layer stored in the memory of the system controller 32. As parameters for determination, the amplitude value Vpp and the offset amount Vo of the tracking error signal are stored for each layer. That is, the amplitude value Vpp2 obtained when the servo parameter for the first recording layer is maintained while the amplitude value Vpp1 and the offset Vo1 when the focus is on the first recording layer and the second recording layer is focused. , And stores the offset Vo2 (see FIG. 3B). After jumping from the first recording layer to the second recording layer, when the tracking error signals Vpp and Vo substantially match Vpp2 and Vo2 for the second recording layer (when they match within a predetermined allowable range). Is determined to have jumped to the second recording layer. The memory of the system controller 32 further stores optimum servo parameters for each layer. Specifically, the servo gain G and the offset OF. If it is determined that the laser beam has surely jumped from the first recording layer to the second recording layer using the determination parameters Vpp and Vo, the servo parameter is switched from the first recording layer to the second recording layer, and the tracking servo is switched. Set to ON. The determination parameters and the optimum servo parameters for each layer are acquired when the apparatus is activated and stored in the memory of the system controller 32. That is, after the apparatus is activated and the optical disk 10 is loaded, the optimum servo parameters of the first recording layer and the second recording layer are acquired. Next, with the tracking servo OFF, the process proceeds to the second recording layer while maintaining the optimum servo parameters of the first recording layer, and the tracking error signal amplitude value Vpp and offset Vo at that time are acquired. These acquisition operations can be executed at the same time as OPC in the test areas of the first recording layer and the second recording layer, for example.

  FIG. 5 is a process flowchart when jumping from the first recording layer to the second recording layer in the present embodiment. The system controller 32 instructs the servo processor 30 to turn off the tracking servo (S101), and maintains the servo parameters at that time, specifically, the offset value added to adjust the amplifier gain and amplitude balance of the servo system. In this state, the lens of the optical pickup 16 is driven to shift the focus surface from the first recording layer to the second recording layer (S102). In the above-described prior art, the focus jump is performed while the tracking servo is ON. However, in the present embodiment, the tracking servo is OFF and the focus jump is performed as described above. When the tracking servo is turned off, disturbance occurs when the laser beam crosses the pit row or groove, which may affect the focus error signal. However, in this embodiment, the tracking error signal is used instead of the focus error signal to determine the jump destination. Because it uses, it does not become a problem.

  After the focus jump, the servo processor 30 detects an open loop tracking error signal (a signal amplified by the set amplifier gain and added with an offset) (S103), and calculates the amplitude value Vpp and the offset value Vo. It detects (S104). The detected amplitude value Vpp and offset value Vo are supplied to the system controller 32. The system controller 32 receives the detected amplitude value Vpp and offset value Vo, reads out the Vpp2 and Vo2 that are determination parameters for the second recording layer, which are scheduled jump destinations, from the memory (S105), and compares the two respectively. Then, it is determined whether or not they match (S106). Specifically, an allowable range ε of amplitude value difference and an allowable range δ of offset value difference are set, and when | Vpp−Vpp2 | ≦ ε and | Vo−Vo2 | ≦ δ are satisfied, it is determined that the two match each other. . ε and δ may be different values. When the detected amplitude value Vpp and offset value Vo both coincide with the amplitude value Vpp2 and offset value Vo2 for the second recording layer, the laser beam surely jumps from the first recording layer to the second recording layer. (S107), the servo processor 30 changes the servo parameter of the tracking servo from the first recording layer to the second recording layer (S108), and turns on the tracking servo (S109). After the on-focus state and the on-track state for the second recording layer, the address is read from the second recording layer, the data is recorded at the desired address, or the data is read from the desired address and supplied to the host. Based on the address read from the second recording layer, it may be verified that the laser beam has further jumped to the second recording layer.

  On the other hand, when the detected amplitude value Vpp and offset value Vo do not coincide with the amplitude value Vpp2 and offset value Vo2 for the second recording layer (when the difference value exceeds the allowable values ε and δ), the target recording is performed. It is determined that the focus recording is not the second recording layer, that is, the focus jump has failed (S110), and the process of S102 is repeated again without adjusting the servo parameters, and the jump to the second recording layer is retried. To do. The number of retries may be counted, and when the count value reaches the upper limit, the focus jump may be stopped and an error message may be output.

  Thus, in this embodiment, the fact that the tracking error signal is different between the first recording layer and the second recording layer is used to verify that the jump has been made to the second recording layer. Since the recording layer is switched to the second recording layer, even if the second recording layer cannot be focused and the first recording layer is returned to, the servo parameter is erroneously switched to the second recording layer and oscillation occurs. Can be prevented.

  In the present embodiment, when the amplitude value Vpp and the offset value Vo both match the amplitude value Vpp2 and the offset value Vo2 for the second recording layer, it is determined that the jump has been made to the second recording layer. When either Vpp or the offset value Vo matches, it may be determined that the jump has been made to the second recording layer. Further, when only the amplitude value Vpp is detected and coincides with Vpp2, it is determined that the jump is made to the second recording layer, or when only the offset value Vo is detected and coincides with Vo2, the jump is made to the second recording layer. You may judge. Also, superiority or inferiority may be set between the amplitude value Vpp and the offset Vo. Further, when either the amplitude value or the offset value matches, it may be provisionally determined that the jump has been made to the second recording layer. In this case, the servo parameter is set to the value for the first recording layer and the second recording layer. The servo parameter may be switched to the second recording layer after temporarily setting to an intermediate value of the target value and confirming that the tracking error signal balance has been improved.

  In this embodiment, the tracking servo signal is detected when the tracking servo is turned off and the jump to the second recording layer is performed while the amplifier gain and offset for the first recording layer are maintained as they are. When jumping to, the amplifier gain and offset may be first switched to values for the second recording layer, and then the tracking error signal may be detected. If it jumps to the second recording layer, the peak value and offset value of the obtained tracking error signal should be correct values (the peak value is a predetermined value and the offset value is almost zero). By confirming this, it can be determined whether or not a jump to the second recording layer has been made.

  FIG. 6 shows a process flowchart when jumping from the first recording layer to the second recording layer in another embodiment. First, the system controller 32 instructs the servo processor 30 to turn off the tracking servo (S201), and switches the servo parameter for the second recording layer (S202). That is, the gain is switched from G1 to G2, and the offset is switched from OF1 to OF2. G2 and OF2 are optimum servo values in the second recording layer, and the amplitude value of the tracking error signal is a predetermined value, and the tracking error signal balance is good (offset is almost zero). Explaining with reference to FIG. 3, the tracking error signal as shown in FIG. 3A is obtained even in the second recording layer.

  After switching the gain and the offset value for the second recording layer, the focus jump from the first recording layer to the second recording layer (S203) and the tracking error signal is detected (S204). Then, the amplitude value Vpp and the offset Vo of the tracking error signal are detected (S205) and supplied to the system controller 32. The system controller 32 determines whether or not the detected Vpp and the offset value Vo are predetermined values (S206), and when it is determined that they are predetermined values, that is, an almost optimal tracking error signal is obtained. Certainly determines that the focus has jumped to the second recording layer (S207). In this case, since the servo parameter has already been switched in S202, the tracking servo is immediately turned ON (S208). On the other hand, if the amplitude value Vpp and the offset value Vo are not predetermined values, it is determined that the jump has not been made to the second recording layer (S209), and the jump to the second recording layer is repeated by repeating the process of S203. Try.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to this, A various change is possible. For example, in the present embodiment, the first recording layer is the front side and the second recording layer is the back side, but the first recording layer may be the back side and the second recording layer may be the front side. Further, the determination parameters Vpp and Vo shown in FIG. 4 may be relative values of another layer (second recording layer) based on a certain layer (first recording layer). In the present embodiment, the optical disc 10 has a two-layer structure including a first recording layer and a second recording layer. However, it may have a three-layer structure or a laminated structure of more layers. In the case of a three-layer structure, determination parameters and servo parameters for each layer are stored in the memory shown in FIG. When storing values based on the first recording layer, jumps from the first recording layer to the second recording layer, or jumps from the first recording layer to the third recording layer, use the values stored in the memory as they are. When the jump from the second recording layer to the first recording layer, or the jump from the second recording layer to the third recording layer, it is converted into a value based on the second recording layer.

1 is an overall configuration diagram of an embodiment. It is a figure which shows the jump from a 1st recording layer to a 2nd recording layer. It is a figure which shows the waveform change of the tracking error signal at the time of the jump from a 1st recording layer to a 2nd recording layer. It is explanatory drawing of the determination parameter and servo parameter which are memorize | stored in the memory of a system controller. It is a processing flowchart of an embodiment. It is a processing flowchart of other embodiments.

Explanation of symbols

  10 optical disk, 16 optical pickup, 30 servo processor, 32 system controller.

Claims (1)

An optical disc apparatus for recording or reproducing data with respect to a multilayer optical disc having at least a first recording layer and a second recording layer,
Means for irradiating the multilayer optical disc with laser light;
Means for shifting the focus surface of the laser beam from the first recording layer to the second recording layer;
Means for releasing tracking servo control when shifting from the first recording layer to the second recording layer and detecting a tracking error signal after the transition;
Means for detecting at least one of an amplitude value or an offset of the detected tracking error signal;
Stores the amplitude value or offset unique to the second recording layer, which is the amplitude value or offset of the tracking error signal obtained when focusing on the second recording layer while maintaining the servo parameters for the first recording layer Means to
The detected amplitude value or offset is compared with the amplitude value or offset unique to the second recording layer, and when both coincide, it is determined that the focus surface of the laser beam has shifted to the second recording layer, and the tracking servo When the parameter setting is switched from the tracking servo parameter for the first recording layer to the tracking servo parameter for the second recording layer, and the two do not match, the focus surface of the laser beam has shifted to the second recording layer. Means to determine that the tracking servo parameter is not switched to the tracking servo parameter for the second recording layer, and to retry the transition;
An optical disc apparatus comprising:

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