JP2011238308A - Optical disk device and recording control method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a recording control method for improving recording quality by recording data with optimum recording power, and an optical disk device for implementing the method.SOLUTION: With test writing on a test write area by an optical pickup, a control unit calculates a theoretical value 20 of the recording power. The control unit calculates a measured value 21 of the recording power by correcting the theoretical value 20 of the recording power based on a β value calculated by a β detection circuit during recording or an asymmetry value. The optical pickup records data on the optical disk with the measured value 21 of the recording power while separating the optical disk in a plurality of areas in a radial direction. The control unit corrects the recording power by using the theoretical value 20 of the recording power and the measured value 21 of the recording power immediately before the recording, when the area of the optical disk to be recorded changes or the rotation speed of the disk is required to be lowered.

Description

  The present invention relates to an optical disc apparatus capable of recording and reproducing an optical disc and a recording control method thereof.

  2. Description of the Related Art Conventionally, when recording data on an optical disc, an optical disc apparatus performs a recording power test generally called OPC (Optimum Power Calibration). In OPC, a test for recording data in a test writing area provided on the innermost or outermost circumference of an optical disc called PCA (Power Calibration Area) is performed, and the optimum recording power is calculated by reading the data recorded on the PCA. Then, the optical disc apparatus records on the optical disc with the calculated recording power. The recording power here is the intensity of the laser beam when the optical disc apparatus records on the optical disc.

  However, since the optimum recording power changes depending on the environment (for example, temperature) at that time, the environment before the start of recording when OPC is performed and the environment after the start of recording after the start of recording. And the optimum recording power is different. For this reason, it has been difficult to optimize the recording power theoretically calculated by OPC until the end of recording.

  Therefore, a method has been proposed in which recording is stopped at regular intervals or at regular intervals, the recorded quality is evaluated by reproducing already recorded data, and the recording power is corrected from the evaluation result (for example, Patent Document 1). A parameter called β value or asymmetry value is used as an index of recording quality, and data is recorded while periodically correcting the recording power using the β value or asymmetry value as an index.

JP 2002-208139 A

  However, the conventional optical disk apparatus has a problem that once recording is started, only the β value or asymmetry value is used as an index for correcting the recording power. Therefore, after the start of recording, correction is appropriately performed based on only the β value or the asymmetry value. Therefore, the actual recording power value may deviate greatly from the theoretical value of the recording power originally obtained by OPC. The β value or asymmetry value is one of the indexes of recording power, but information (for example, error rate) obtained by calculating the theoretical value of recording power by OPC is naturally necessary information for calculating the recording power. In the correction of the recording power relying only on the β value or the asymmetry value, it is difficult to obtain the optimum recording power. As a result, there is a problem that recording cannot be performed with an appropriate recording power and recording quality is deteriorated.

  Therefore, the present invention corrects the difference between the actual recording power value corrected using the β value or the asymmetry value after the start of recording and the theoretical value of the recording power calculated by OPC, so that the optimum recording power can be obtained. An object of the present invention is to provide an optical disc apparatus for recording data and improving recording quality, and a recording control method therefor.

  In order to achieve the above object, the present invention provides a rotational drive unit for rotating an optical disc having a test writing area, an optical pickup for recording and reproducing data on the optical disc, and a recording power of a laser beam emitted from the optical pickup. A laser control circuit for controlling the signal, a reproduction signal detection circuit for generating an RF signal based on a signal obtained from the optical pickup and performing a decoding process, and a β value for calculating a β value or an asymmetry value based on the RF signal A detection circuit and a controller for determining a recording power based on at least the β value or the asymmetry value, and increasing the recording power from the inner periphery to the outer periphery while increasing the recording power in the radial direction. In an optical disc apparatus that performs recording while distinguishing into a plurality of areas, the optical pickup has a test writing in the test writing area. The control unit calculates the theoretical value of the recording power, and the control unit corrects the theoretical value of the recording power based on the β value or the asymmetry value calculated from the β detection circuit during recording. An actual recording power value is calculated, the optical disc is discriminated into a plurality of areas in the radial direction, and the optical pickup records data on the optical disk according to the actual recording power value. The present invention relates to an optical disc apparatus that corrects a recording power by using the theoretical value of the recording power and the measured value of the recording power immediately before the recording when the rotational speed needs to be lowered. is there.

  Since the present invention is configured as described above, information on the theoretical value of the recording power is newly reflected in the measured value of the recording power that is corrected only by the β value or the asymmetry value when the recording area changes. The recording power can be calculated. As a result, the deviation between the theoretical value of the recording power and the actual measurement value can be corrected, so that data can be recorded with a more optimal recording power. Accordingly, the recording quality is improved.

1 is a block diagram of an optical disc apparatus according to Embodiment 1 of the present invention. The figure which shows the relationship between the recording address and recording power of the recording control method in Embodiment 1 of this invention. Flowchart of recording control method according to Embodiment 1 of the present invention The figure which shows the relationship between the recording power of the result of having performed OPC in Embodiment 1 of this invention, and an error rate. The figure which shows the relationship between the recording power of the result of having performed OPC in Embodiment 1 of this invention, and (beta) value. Flowchart of method for calculating area head power of recording control method according to Embodiment 1 of the present invention The figure which shows the relationship between the recording address and recording power of the recording control method in Embodiment 2 of this invention. Flowchart of CLV start power calculation method of recording control method according to Embodiment 2 of the present invention

  According to a first aspect of the present invention, a rotational drive unit that rotates an optical disc having a test writing area, an optical pickup that records and reproduces data on the optical disc, and a recording power of laser light emitted from the optical pickup are controlled. A laser control circuit for performing a decoding process by generating an RF signal based on a signal obtained from the optical pickup, and a β detection circuit for calculating a β value or an asymmetry value based on the RF signal And a control unit for determining recording power based on at least the β value or the asymmetry value, and increasing the recording power as the recording position of the optical disk changes from the inner periphery to the outer periphery. In an optical disc apparatus that performs recording by distinguishing between areas, the optical pickup performs trial writing in the trial writing area. Thus, the control unit calculates the theoretical value of the recording power, and the control unit corrects the theoretical value of the recording power based on the β value or the asymmetry value calculated from the β detection circuit during recording. The optical pickup records the data on the optical disc according to the measured value of the recording power by dividing the optical disc into a plurality of regions in the radial direction, and the rotation speed of the optical disc changes when the recorded optical disc region changes. The present invention relates to an optical disc apparatus that corrects the recording power by using the theoretical value of the recording power and the measured value of the recording power immediately before recording when the recording power needs to be lowered.

  According to the first aspect of the present invention, newly recorded information reflecting the theoretical value of the recording power is also reflected in the measured value of the recording power corrected only by the β value or the asymmetry value triggered by the change of the recording area. Power can be calculated. As a result, the deviation between the theoretical value of the recording power and the actual measurement value can be corrected, so that data can be recorded with a more optimal recording power. Accordingly, the recording quality is improved.

  According to a second aspect of the present invention, there is provided a recording control method for performing recording while discriminating a plurality of areas in the radial direction of the optical disk while increasing the recording power as the recording position of the optical disk changes from the inner periphery to the outer periphery. To calculate the theoretical value of the recording power, record the theoretical value of the recording power with the β value or the asymmetry value, and record with the measured value of the recording power. Recording control, wherein the recording power is corrected using the theoretical value of the recording power and the measured value of the recording power immediately before the recording when the measured value or the measured value of the recording power is not a suitable value Regarding the method.

  According to the second aspect of the present invention, newly recorded information reflecting the theoretical value of the recording power is reflected in the measured value of the recording power corrected only by the β value or the asymmetry value triggered by the change of the recording area. Power can be calculated. As a result, the deviation between the theoretical value of the recording power and the actual measurement value can be corrected, so that data can be recorded with a more optimal recording power. Accordingly, the recording quality is improved.

  According to a third aspect of the present invention, an error rate at a certain recording speed is calculated by performing trial writing on an optical disc, and a recording power serving as a reference in each of the plurality of areas is calculated based on the error rate. The present invention relates to a recording control method.

  According to the third aspect of the present invention, the recording power serving as the reference for each area can be calculated from the error rate. Accordingly, since the theoretical value of the recording power can be obtained with reference to the recording power as each reference, the theoretical value of the recording power that becomes a suitable β value or asymmetry value with a low error rate can be obtained.

  According to a fourth aspect of the present invention, there is provided a recording control method characterized in that the range of the amount of change in recording power in the plurality of areas is determined by the recording power as the reference.

  According to the fourth aspect of the present invention, since the range of the amount of change in recording power in each area can be determined, the theoretical value of the recording power in each area can be obtained based on this range. This can be used as a reference for determining the increase rate of the recording power in each area.

  According to a fifth aspect of the present invention, by performing trial writing on an optical disc, the relationship between the β value or asymmetry value at a certain recording speed and the recording power is calculated, and the β value or asymmetry value having a different recording speed is calculated from this relationship. The present invention relates to a recording control method that corrects recording power using a difference in inclination.

  According to the fifth aspect of the present invention, the recording power can be corrected in consideration of the difference in the inclination of the β value or the asymmetry value with respect to the recording power due to the difference in recording speed.

  According to a sixth aspect of the present invention, when it is determined that the measured value of the recording power is not a suitable value, the recording speed is lowered, and the recording speed is suitable for the recording speed using the theoretical value of the recording power and the measured value of the recording power. The present invention relates to a recording control method characterized in that the recording power is calculated and the rotational speed of the optical disk is changed in accordance with the recording speed in order to fix the recording speed and the recording power.

  According to the sixth aspect of the present invention, even if the measured value of the recording power does not become a suitable value, it can be dealt with and the recording quality can be maintained.

(Embodiment 1)
Hereinafter, an optical disc device and a recording control method thereof according to Embodiment 1 of the present invention will be described with reference to the drawings. The optical disk apparatus according to the present embodiment is an apparatus capable of recording and reproducing data on an optical disk. When recording data, the optical disk is divided into a plurality of areas. Therefore, when the recording area of the optical disk changes, the intensity of the laser light applied to the optical disk is corrected again, so that the recording can be performed with the intensity of the laser light according to the situation at that time. Thereby, high recording quality can be realized.

  First, the configuration of the optical disc apparatus according to the present embodiment will be described with reference to FIG. FIG. 1 is a block diagram of an optical disc apparatus according to Embodiment 1 of the present invention.

  The optical disc 1 is a recording medium on which data is recorded, and specifically, is a CD-R, DVD-R, Blu-ray disc or the like. The optical pickup 2 records the optical disk 1 by emitting laser light to the optical disk 1, irradiates the optical disk 1 with laser light, and receives the reflected laser light with an optical sensor (not shown). Play back. The reproduction signal detection circuit 3 generates an analog signal such as an RF signal, a focus error signal, and a tracking error signal based on the signal received by the optical pickup 2. The focus error signal and the tracking error signal are sent to the servo control circuit 8, and the RF signal is sent to the β detection circuit 9. The spindle motor 4 as a rotation drive unit is a motor that rotates the optical disc 1. Since the optical disc apparatus according to the present embodiment uses a CAV (Constant Angular Velocity) method, the spindle motor 4 when recording on the optical disc 1 is used. The rotational speed is basically constant, but it may be necessary to change the rotational speed depending on the situation (details will be described later). The traverse mechanism 5 moves the optical pickup 2 on which the carriage is mounted in the radial direction. The pickup module 11 includes an optical pickup 2, a spindle motor 4, and a traverse mechanism 5.

  The laser control circuit 6 controls the intensity of the laser beam emitted from the optical pickup 2. The intensity of the laser beam when the optical disc apparatus performs recording on the optical disc 1 is defined as the recording power. The recording control circuit 7 records a plurality of control methods in the laser control circuit 6, and sends one of the control methods to the laser control circuit 6.

  The servo control circuit 8 includes an ON / OFF circuit, an arithmetic circuit, a filter circuit, an amplifier circuit, and the like, and an object provided in the optical pickup 2 based on a focus error signal and a tracking error signal sent from the reproduction signal detection circuit 3. A lens position signal indicating the relative positional relationship between the lens and the carriage is generated and output to the optical pickup 2. The optical pickup 2 performs focus control and tracking control based on the signal. The focus control refers to control for focusing the laser beam emitted from the optical pickup 2 on the optical disc 1, and the tracking control refers to the control of the optical pickup 2 so that the laser beam emitted from the optical pickup 2 strikes the correct position of the optical disc 1. It refers to controlling the position.

  The β detection circuit 9 calculates a β value from the RF signal sent from the reproduction signal detection circuit 3, and sends this β value to the control circuit 10. Here, the β value is defined by β = (H1 + L1) / (H1−L1) using a positive peak level H1 and a negative peak level L1 with respect to the AC reference voltage of the RF signal having the longest data amplitude. H1 + L1 is the difference between the positive side amplitude and the negative side amplitude, and H1-L1 is the amplitude.

  The control circuit 10 constitutes a control unit of the present embodiment, and signals sent from the respective parts such as the reproduction signal detection circuit 3, the laser control circuit 6, the recording control circuit 7, the servo control circuit 8, and the β detection circuit 9 are inputted. Then, these signal processings are performed, and each part is controlled by outputting the calculation result (signal) to each part. Therefore, the control circuit 10 includes at least an arithmetic processing circuit such as a CPU and an MPU, and a recording circuit such as a ROM and a RAM.

  Further, the optical disk apparatus in the present embodiment adopts the CAV method, and CAV means constant angular velocity. When the optical disc apparatus records or reproduces the optical disc 1, the spindle motor 4 always rotates the optical disc 1 at a constant rotational speed, that is, records while keeping the angular velocity on the recording surface constant. This method is called a CAV method. The closer the recording position of the optical disc 1 is to the center, the shorter the distance that goes around the optical disc 1 is, so that the speed of passing through the optical pickup 2 naturally increases. Therefore, it is preferable to make the recording density of the central portion coarse in order to perform sufficient reading.

  On the other hand, there is a CLV (Constant Linear Velocity) method for the CAV method, and CLV means a constant linear velocity. The CLV method is a method of performing recording and reproduction while maintaining a constant linear velocity at which the optical disk 1 passes through the optical pickup 2 when the optical disk apparatus records or reproduces the optical disk 1. Therefore, the spindle motor 4 changes the rotation speed of the optical disc 1 in order to keep the linear velocity constant. Therefore, when recording on the inner periphery of the optical disc 1, the rotational speed of the optical disc 1 is increased, and the rotational speed of the optical disc 1 is decreased as the recording position becomes the outer periphery.

  The optical disc apparatus according to the present embodiment is configured as described above, and can record and reproduce the optical disc 1. The control circuit 10 is a control unit that implements the recording control method described below.

  Next, a recording control method according to the present embodiment, particularly a recording power control method, will be described with reference to FIGS. 2 is a diagram showing the relationship between the recording address and the recording power of the recording control method according to the first embodiment of the present invention, FIG. 3 is a flowchart of the recording control method according to the first embodiment of the present invention, and FIG. FIG. 5 shows the relationship between recording power and error rate as a result of performing OPC in Embodiment 1, and FIG. 5 shows the relationship between recording power and β value as a result of performing OPC in Embodiment 1 of the present invention. FIG. 6 and FIG. 6 are flowcharts of the area head power calculation method of the recording control method according to the first embodiment of the present invention.

  First, the outline of the recording control method in the present embodiment will be described with reference to FIG. FIG. 2 shows the transition of recording power when the recording address is increased when the optical axis apparatus of the present embodiment performs recording on the optical disc 1 with the recording power on the vertical axis and the recording address on the horizontal axis. The recording address represents the recording position of the optical disc 1, and means that the recording address goes to the outer periphery of the optical disc as the recording address increases. Therefore, since the optical disk apparatus according to the present embodiment employs the CAV method, the linear velocity at which the optical disk 1 passes through the optical pickup 2 inevitably increases as the recording address increases (hereinafter, this is the case when recording is performed). The linear velocity is the recording velocity). For this reason, the recording speed increases in parallel with the recording address on the horizontal axis. Therefore, the horizontal axis in FIG. 2 when performing recording by the CAV method is not only the recording address but also the recording speed.

  Further, as can be seen from FIG. 2, in the present embodiment, the control is performed so that the recording power increases as the recording address increases (the recording position goes toward the outer periphery). This is because as the recording speed increases, it is necessary to increase the recording power, thereby maintaining the recording quality.

  In the present embodiment, when recording on the optical disk 1, an appropriate recording power is determined by dividing into a plurality of areas 31-33. In addition, the description about each area | region 31-33 is mentioned later. OPC (trial writing) is performed in the trial writing area 30 which is PCA, and a theoretical value 20 of an appropriate recording power of the optical disc 1 is calculated. What is determined here is the recording power for starting recording in the areas 31 to 33 (hereinafter also referred to as the area head power of the theoretical value 20) and the offset amount of the recording power that is added as the recording speed increases. is there. That is, the recording power increases in proportion to the recording address. Here, the head power 31 a is the area head recording power of the theoretical value 20 in the area 31, the head power 32 a is the area head recording power of the theoretical value 20 in the area 31, and the head power 33 a is the area head recording power in the area 33. The test writing recording speed 30b is a reference recording speed in the test writing area 30, the reference recording speed 31b is a reference recording speed in the area 31, the reference recording speed 32b is a reference recording speed in the area 32, and the reference recording speed 33b is The recording speed is a reference in the area 33.

  However, the environment when the optimum theoretical value 20 is obtained by OPC differs from the environment after the actual recording is started due to, for example, a temperature change. For this reason, it is not promised that the theoretical value 20 obtained by OPC is always optimal even after the start of recording. Therefore, in the present embodiment, correction is appropriately performed based on the β value (hereinafter also referred to as β value correction).

  When β value correction is performed, recording is temporarily stopped, data recorded by the optical pickup 2 is reproduced, and a β value is calculated via the reproduction signal detection circuit 3 and the β value detection circuit 9. Using the calculated β value as a target β value suitable for the situation, a recording power is calculated such that the β value at the current recording power becomes the target β value, and recording is resumed with this recording power. The recording power determined while appropriately performing this β value correction becomes the actual measurement value 21. As a result, the actual measurement value 21 is corrected by relying only on the β value in each of the regions 31 to 33, so that the actual measurement value 21 and the theoretical value 20 obtained by OPC may gradually deviate.

  Therefore, when the recording area changes, only the β value is obtained by obtaining a recording power for starting recording in a new area again using the theoretical value 20 and the actual measurement value 21 (hereinafter also referred to as the area head power of the actual measurement value 21). Therefore, it is possible to prevent the determination of the recording power depending on the recording quality and to improve the recording quality. It should be noted that the β value correction may be performed every certain time or every recording address at a certain interval.

  The flow of the recording power control method in the present embodiment will be described collectively with reference to FIG. When recording on the optical disc 1 is started, first, OPC is performed on the innermost circumference (trial writing area 30) of the optical disc to determine a theoretical value 20 (S1). Next, the recording power is determined while appropriately correcting the β value based on the theoretical value 20, and the optical pickup 2 records data on the optical disc 1 with the determined recording power (S2). Next, when the data recording reaches the end of the area (S3), the recording power is recalculated to determine the next area head power (S4), and the recording is resumed from the area head power obtained here. (S2). If the end of the area is not reached or if it is not necessary to reduce the recording speed (S3), the recording is continued (S5). When the data is recorded up to the final address or when all the data to be recorded is recorded (S6), the recording is finished. The case where the recording speed needs to be lowered will be described in the second embodiment.

  Here, the OPC in this embodiment will be described in detail with reference to FIGS. As described above, in the OPC, the head powers 31a to 33a are determined, and the offset amount accompanying the increase in the recording speed in each of the areas 31a to 33a is determined. One of the indexes for making this determination is the above-described β value, and another index includes an error rate shown in FIG.

  The reference error rate 30c is an error rate when the recording power is changed when data is recorded at the trial writing recording speed 30b. The reference error rate 31c is an error rate when the recording power is changed when data is recorded at the reference recording speed 31b. The reference error rate 32c is an error rate when the recording power is changed when data is recorded at the reference recording speed 32b. The reference error rate 33c is an error rate when the recording power is changed when data is recorded at the reference recording speed 33b.

  The error rate here is the ratio between the recorded data and the data that could not be correctly reproduced when recording while changing the recording power while fixing the same data to a certain recording speed. Smaller reference error rates 30c to 33c are preferable because high recording quality can be maintained. The reference recording speeds 31b to 33b are preferably near the center of the recording speed in each of the areas 31 to 33, but are not particularly limited.

  Since each of the reference error rates 30c to 33c is a substantially parabolic graph, the recording power of the power region 30e having a small error rate is adopted as the reference error rate 30c, and the center value of the power region 30e is used as the reference in the test writing region 30. The recording power is 30d. Similarly, the reference recording power 31d is the center value of the power area 31e, the reference recording power 32d is the center value of the power area 32e, and the reference recording power 33d is the center value of the power area 33e.

  Thereby, each reference recording power 30d-33d can be made into recording power with a small error rate in the recording speed 30b-33b used as the reference | standard of each area | region 30-33. Therefore, the reference recording powers 31d to 33d are taken into account when determining the head powers 31a to 33a and the offset amounts of the areas 31 to 33 in the OPC. That is, the theoretical value 20 is calculated so as to pass near each of the reference recording powers 31d to 33d.

  The characteristics of the optical disc 1 vary depending on the type of the optical disc 1. In other words, the required offset powers of the head powers 31a to 33a and the areas 31 to 33 differ depending on the manufacturer and product of the optical disc 1. Therefore, it is desirable to calculate the theoretical value 20 in advance for each type of the optical disc 1 and hold the result in the control circuit 10. Thereby, the theoretical value 20 can be read according to the type of the optical disk 1 loaded. Therefore, in the OPC, the theoretical value 20 can be automatically read from the control circuit 10 by determining the type of the optical disc 1 only by determining the β value and the reference recording powers 31d to 33d. Thereby, since the arithmetic processing performed by OPC can be reduced, the time for calculating the theoretical value 20 can be shortened. Further, only the offset amount of each of the areas 31 to 33 is stored in the control circuit 10 for each type of the optical disc 1, and the head powers 31a to 33a may be calculated from the result of OPC.

  The reference recording powers 30d to 33d in the present embodiment are the center values of the power regions 30e to 33e, but may be simply the minimum values of the reference error rates 30c to 33c. However, since the reference error rates 30c to 33c show a substantially parabolic graph but are not left and right, the error rate does not increase as the distance from the minimum value of the reference error rates 30c to 33c increases. Therefore, if the minimum value is set, there is a possibility that the error rate is greatly increased only by slightly deviating the recording power. When actually recording on the optical disc 1, even if the actual recording power value 20 with respect to the reference recording speeds 31b to 33b does not match the values of the reference recording powers 31d to 33d, they should be within the ranges of the power regions 30e to 33e. High recording quality can be maintained. Accordingly, in consideration of the possibility that each of the reference recording powers 31d to 33d may be different from the actual measurement value 21, each reference recording power 31d to 33d has a range in the error area in the sense that the error rate has a width. A center value of 33e is desirable. Thereby, it is possible to more reliably perform recording with a recording power with a low error rate.

  Further, the wide width of each of the power areas 31e to 33e means that a low error rate can be maintained even with a change in recording power, and is related to the offset amount of the theoretical value 20 in each of the areas 31 to 33. Since the usable recording power area is limited when the area width is narrow like the power area 31e, the change in the recording power in the area 31 is preferably small. Therefore, the gradient of the theoretical value 20 in the region 31 cannot be increased. That is, the offset amount added to the recording power with respect to the increase in recording speed cannot be increased. On the other hand, since the width of the power area 32e is wide, the area of the recording power that can be used in the area 32 can be increased. Therefore, the theoretical value 20 in the region 32 can be a large slope.

  As described above, the possible change range of the recording power in each of the areas 31 to 33 can be obtained with reference to the width of each of the power areas 31e to 33e. Thereby, the offset amount in each area | region 31-33 of the theoretical value 20 can be determined.

  Next, the β value when the recording power changes will be described with reference to FIG. The reference β value 30f is a β value when recording is performed while changing the recording power at the trial writing recording speed 30b. The reference β value 31f is the β value when the recording power is changed at the reference recording speed 31b, and the reference β value 32f is the β value when the recording power is changed at the reference recording speed 32b. The value 33f is the β value when recording is performed while changing the recording power at the reference recording speed 33b. As can be seen from FIG. 5, the reference β values 30f to 33f increase in proportion to the recording power, and the rate of increase of the β value with respect to the recording power decreases as the recording speed decreases. Accordingly, the β value increases as the recording power increases and the recording speed decreases, and the β value changes according to the situation.

  As described above, since the change in the β value varies depending on the recording speed and the recording power, recording is performed while appropriately correcting the β value to cope with this change. Therefore, there is a discrepancy between the theoretical value 20 obtained by OPC and the actually measured value 21 determined while correcting the β value as recording is performed. However, the optimum recording power is not determined only by the β value, and the theoretical value 20 by the OPC should be referred to. Therefore, in the present embodiment, when the region is crossed, the region head power of the actual measurement value 21 in which the deviation between the theoretical value 20 and the actual measurement value 21 is corrected is calculated.

  Hereinafter, a method of calculating the area head power of the actual measurement value 21 of the area 33 in FIG. 2 will be described with reference to the flowchart of FIG. FIG. 6 is a flowchart illustrating in detail the power recalculation (S4) in FIG.

  When the recording to the end of the area 32 is completed, the recording is temporarily stopped, and the calculation of the area head power of the actually measured value 21 in the area 33 is started (S11). First, the increment of the theoretical value 20 in the region 32 is subtracted, that is, the offset amount in the region 32 is subtracted. The offset amount here is a difference between the leading power 32a of the area 32 and the theoretical value 20 of the recording power at the end of the area 32 (S12). Next, divide by the head power ratio. The head power ratio here is (head power 32a) / (reference recording power 30d) (S13). Through the above steps, the amount of increase in recording power due to the theoretical value 20 can be subtracted from the current recording power. However, the actual measurement value 21 deviates from the theoretical value 20 by the β value correction, and the inclination of the change of the β value varies depending on the recording speed as described above. Therefore, in order to consider the slope of the change in β value, it is divided by the difference in the slope of the β value. Here, the difference in the slope of the β value is (reference β value 30f) / (reference β value 32f). (S14). Then, by multiplying the recording power by the head power ratio (S15), the area head power in the area 33 can be obtained (S16). The head power ratio here is (head power 33a) / (reference recording power 30d). As described above, the area head power of the actual measurement value 21 is recalculated, and recording is resumed with this area head power.

  As described above, in OPC, at least each head power 31a to 33a, an offset amount in each region 31 to 33, and a β value and its inclination that differ depending on the recording speed are calculated. Further, the head power ratio (each head power) (Ratio between 31a to 33a and the reference recording power 30d) and the difference in the slope of the β value can be obtained. As a result, the actual measured value 21 of the recording power determined by relying only on the β value correction is corrected using information based on the theoretical value 20 calculated by OPC when straddling the area. Therefore, in the recording control method according to the present embodiment, the β value is appropriately corrected so that the measured value 21 corresponding to the change in the recording state such as heat is more optimal for the recording speed reflecting the information of the theoretical value 20 by OPC. Data can be recorded on the optical disc 1 with a high recording power. Thereby, the recording quality can be improved.

  In the present embodiment, the recording power is corrected using the β value calculated from the β value detection circuit 9, but an asymmetry value that can be calculated from the RF signal may be used in the same manner as the β value. The asymmetry value is a value obtained by normalizing the difference between the average level of the RF signal having the longest data amplitude and the average level of the RF signal having the shortest data amplitude with the longest data. The positive peak level H1 and the negative peak level L1 of the longest data amplitude with respect to the AC reference voltage of the RF signal having the longest data amplitude, and the positive peak level with respect to the AC reference voltage of the RF signal having the shortest data amplitude are H2 and the negative peak level. Using L2 and the above four parameters, asymmetry value = [(H1 + L1) / 2− (H2 + L2) / 2] / (H1−L1).

  Since it is calculated from the same RF signal, the asymmetry value can be used as a reference for the recording power instead of the β value. That is, the asymmetry value can be used as an index of the recording power, like the β value. However, even if the recording power is corrected based on either the β value or the asymmetry value, the effect is the same (that is, the recording power correction result is the same). Therefore, in the present embodiment, similar actions and effects can be obtained even if the β value is replaced with an asymmetry value.

(Embodiment 2)
Hereinafter, an optical disc device according to Embodiment 2 of the present invention will be described with reference to FIGS. FIG. 7 is a diagram showing the relationship between the recording address and the recording power of the recording control method according to Embodiment 2 of the present invention, and FIG. 8 is a flowchart of the CLV start power calculation method of the recording control method according to Embodiment 2 of the present invention. It is. Here, members having the same configurations and functions as those of the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  In the present embodiment, a case will be described in which the recording is changed to the CLV method in the middle when the normal CAV method is used for recording. Factors for changing from the CAV system to the CLV system include LPC errors and servo errors. An LPC error is an error when the upper limit of recording power is exceeded. The upper limit value of the recording power is determined in advance for safety and by factors such as the characteristics of the optical pickup, and is recorded in the control circuit 10. When the actually measured value 21 subjected to the β value correction exceeds the upper limit value, the control circuit 10 instructs the servo control circuit 8 to lower the recording speed. As a result, the servo control circuit 8 decreases the rotation speed of the spindle motor 4, so that the rotation speed of the optical disk 1 decreases. The servo error is an error when the amount of eccentricity of the optical disc 1 being recorded is larger than the specified amount. During the recording, the servo control circuit 8 measures the amount of eccentricity of the optical disk 1, and when the amount of eccentricity exceeds a specified value, the control circuit 10 instructs the servo control circuit 8 to lower the recording speed. As a result, the servo control circuit 8 reduces the rotational speed of the spindle motor 4. Accordingly, since the recording speed is lowered by the error, it is naturally necessary to reduce the recording power.

  Therefore, for LPC errors, the recording power required to maintain the recording quality is reduced by lowering the rotational speed of the optical disc 1. Thereby, since the recording power can be lowered, the recording quality can be maintained. For servo errors, the servo quality is reduced by lowering the rotation speed of the spindle motor 4, so that the recording quality can be maintained. As described above, the optical disk apparatus according to the present embodiment can cope with LPC errors and servo errors.

  Further, in the present embodiment, a recording power suitable for a recording speed that decreases as the rotational speed of the spindle motor 4 is decreased is newly calculated. At this time, when the rotation speed of the spindle motor 4 is lowered and the rotation speed is made constant, that is, when the rotation speed of the spindle motor 4 is lowered, but the recording is continued by the CAV method, the rotation speed is different, and therefore it is inevitably obtained by OPC. The theoretical value 20 cannot be an appropriate recording power. That is, the head powers 31a to 33a, the reference recording speeds 31b to 33b, the reference recording powers 30d to 33d, and the like, which are parameters for obtaining the theoretical value 20, are different from each other in the rotation speed of the spindle motor 4, that is, the angular speed. Therefore, it cannot be used as an index for newly calculating the recording power. Accordingly, the CAV method is switched to the CLV method as the rotation speed of the spindle motor 4 is decreased. As a result, the optimum recording power can be obtained from the parameters calculated from the OPC, and recording can be performed to the end with this recording power.

  Hereinafter, a method of calculating the recording power that is fixed after the CLV method when switching from the CAV method to the CLV method will be described. When the control circuit 10 determines that it is necessary to lower the recording speed due to an LPC error or servo error during recording, the recording power when the CLV method starts (hereinafter referred to as CLV start power) in order to switch from the CAV method to the CLV method. ) Calculation starts. That is, FIG. 8 is a flowchart illustrating in detail the power recalculation (S4) of FIG.

  Hereinafter, a method for calculating the CLV start power will be described with reference to the flowchart of FIG. First, recording is stopped at the stage when the CAV method is completed, and calculation of CLV start power is started (S21). Next, the offset amount is subtracted. The offset amount here is the difference between the leading power 32a of the area 32 and the recording power immediately before switching to the CLV system (S22). Then divide by the head power ratio. The head power ratio here is (head power 32a) / (reference recording power 30d) (S23). Then, in order to consider the change in the slope of the β value corresponding to the recording speed, it is divided by the difference in the slope of the β value. The difference in the slope of the β value here is (reference β value 30f) / (reference β value 32f) (S24). Next, the reference recording power ratio is applied. The reference recording power ratio here is (reference recording power 32d) / (reference recording power 30d) (S25). Thereby, the recording power for starting the CLV system is determined (S26), and the recording is resumed with this recording power. After changing to the CLV system, the CAV system is not restored. For this reason, it is not necessary to recalculate the area head power of the actual measurement value 21 when straddling the area. Therefore, in the flowchart of FIG. 3, even if the recording address arrives at the end of the area (S3), the power is not recalculated (S4).

  Since the information of the theoretical value 20 can be reflected in the actual measurement value 21 by determining the CLV start power by the above procedure, the CLV start power suitable for the situation can be calculated. In this embodiment, the recording speed is lowered to the reference recording speed 32b, and the CLV start power suitable for the reference recording speed 32b is obtained. However, the amount of the recording speed to be lowered differs depending on the recording speed at that time. That is, when recording is performed at a recording speed equal to or lower than the reference recording speed 31b, the recording speed is lowered to the trial writing recording speed 30c. Similarly, when recording is performed between the reference recording speed 31b and the reference recording speed 32b, the recording speed is lowered to the reference recording speed 31b, and recording is performed between the reference recording speed 32b and the reference recording speed 33b. If the recording speed is lower than the reference recording speed 32b, the recording speed is reduced to the reference recording speed 33b. Therefore, since the reference recording speed to be reduced is selected according to the recording speed at that time, it is not necessary to lower the recording speed more than necessary. For this reason, even if an LPC error or a servo error occurs, no particular change in recording speed and recording power is required, so that the recording quality can be maintained.

  As described above, in this embodiment, even if an LPC error or a servo error occurs, these errors can be dealt with by switching from the CAV method to the CLV method. Therefore, data can be recorded more reliably to the end. Furthermore, when calculating the CLV start power, the information of the theoretical value 20 by OPC can be reflected in the actual measurement value 21 corresponding to a change in heat or the like by correcting the β value. For this reason, even if the CAV method is switched to the CLV method, the recording quality can be maintained.

  In the present embodiment, similar to the first embodiment, similar actions and effects can be obtained even if the β value is replaced with an asymmetry value.

  The present invention can be applied to an optical disc apparatus capable of determining an optimum recording power when recording on an optical disc.

DESCRIPTION OF SYMBOLS 1 Optical disk 2 Optical pick-up 3 Reproduction | regeneration signal detection circuit 4 Spindle motor 5 Traverse mechanism 6 Laser control circuit 7 Recording control circuit 8 Servo control circuit 9 β detection circuit 10 Control circuit 11 Pickup module 20 Theoretical value 21 Actual value 30 Trial writing area 31, 32, 33 area 31a, 32a, 33a start power 30b trial writing recording speed 31b, 32b, 33b reference recording speed 30c, 31c, 32c, 33c reference error rate 30d, 31d, 32d, 33d reference recording power 30e, 31e, 32e, 33e Power region 30f, 31f, 32f, 33f Reference β value

Claims (6)

A rotation drive unit for rotating the optical disc having the test writing area;
An optical pickup for recording and reproducing data on an optical disc;
A laser control circuit for controlling the recording power of the laser light emitted from the optical pickup;
A reproduction signal detection circuit that generates an RF signal based on a signal obtained from the optical pickup and performs a decoding process;
A β detection circuit for calculating a β value or an asymmetry value based on the RF signal;
A control unit for determining recording power based on at least the β value or asymmetry value,
In an optical disc apparatus for performing recording by discriminating an optical disc into a plurality of regions in the radial direction while increasing the recording power as the recording position of the optical disc changes from the inner circumference to the outer circumference,
The control unit calculates a theoretical value of recording power by performing trial writing in the trial writing area by the optical pickup,
The control unit calculates an actual recording power value while correcting the theoretical value of the recording power based on a β value or an asymmetry value calculated from a β detection circuit during recording,
The optical pickup records data on the optical disk according to the measured value of the recording power by distinguishing the optical disk into a plurality of areas in the radial direction,
When the area of the optical disk to be recorded changes or when it is necessary to reduce the rotational speed of the optical disk, the control unit uses the theoretical value of the recording power and the measured value of the recording power immediately before recording to record power. An optical disc apparatus for correcting the above. In a recording control method for performing recording by distinguishing an optical disc into a plurality of regions in the radial direction while increasing the recording power as the recording position of the optical disc is changed from the inner circumference to the outer circumference,
Calculate the theoretical value of recording power by performing trial writing on the optical disc,
Recording with the measured value of the recording power calculated while correcting the theoretical value of this recording power with the β value or asymmetry value,
When the area of the optical disk to be recorded changes or when the actual recording power value is not a suitable value, the recording power is corrected using the theoretical value of the recording power and the actual recording power value immediately before recording. And a recording control method. 3. The error rate at a certain recording speed is calculated by performing trial writing on the optical disc, and the recording power as a reference in each of the plurality of areas is calculated based on the error rate. The recording control method described. The recording control method according to claim 3, wherein a range of a change amount of each recording power in the plurality of areas is determined based on the recording power as each reference. By performing trial writing on the optical disc, the relationship between the β value or asymmetry value at a certain recording speed and the recording power is calculated, and the recording power is calculated using the difference in the slope of the β value or asymmetry value at different recording speeds from this relationship. The recording control method according to claim 2, wherein correction is performed. If it is determined that the measured value of the recording power is not an appropriate value, the recording speed is lowered, and the recording power suitable for the recording speed is calculated using the theoretical value of the recording power and the measured value of the recording power. 3. The recording control method according to claim 2, wherein the rotational speed of the optical disk is changed according to the recording speed in order to fix the speed and the recording power.

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