JP2009093766A - Optical disk device and its focus control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical disk device where an optimal position of an objective lens for using the optical disk can be determined considering the displacement and the curvature of the recording layer of the optical disk, even when using optical disks with large displacement and curvature of recording layer, and to provide its focus control method. <P>SOLUTION: The optical disk device includes a memory 13 storing a reference focus value, and a CPU 14 which generates a first modified focus value by adding a predetermined value to the reference focus value and a second modified focus value by subtracting a predetermined value from the reference focus value. The CPU 14 records a test data based on the reference focus value, and determines which of the reference focus value and the first and second modified focus values should be used for recording the test data, based on the ratios of the positive-side amplitude amount and the negative-side amplitude amount of the focus error-signal generated when the test data is reproduced, to the reference voltage. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an optical disc apparatus that performs at least one of recording and reproduction of information on an optical disc and a focus control method thereof.

  When recording information on an optical disc or reproducing information recorded on an optical disc, it is necessary to focus light emitted from a light source on the recording surface of the optical disc. For this condensing, a condensing lens called an objective lens is usually used. When performing recording or playback on an optical disc, focus control is performed to keep the distance between the recording surface of the optical disc and the objective lens at the optimum distance by changing the position of the objective lens, and the objective lens is emitted from the objective lens by changing the tilt of the objective lens. By performing tilt control that keeps the light perpendicular to the recording surface of the optical disc, the light emitted from the light source can be optimally condensed on the recording surface of the optical disc.

  The optical disc apparatus stores a reference focus value that serves as a reference when the objective lens is focus-controlled with respect to the optical disc. This is an effective reference value when using an ideal optical disc.

  However, the actual optical discs may be misaligned or warped with respect to the ideal optical disc due to manufacturing variations. Therefore, it is necessary to improve the recording quality by changing the reference value of the tilt control.

  Since the position of the recording layer of the optical disc and the warpage of the optical disc cannot be directly measured in actual use, test data is recorded while changing the position and tilt of the objective lens on the optical disc used as a substitute. By reproducing the test data and performing a certain check process, the conditions for the best recording quality of the optical disc to be used are selected from the conditions used for recording the test data, and the position and tilt of the objective lens are determined. ing.

  FIGS. 14, 15, and 16 are diagrams showing the range of combinations of focus control values and tilt control values that allow focus control, and FIG. 14 uses an ideal optical disc that has no recording layer misalignment or warping. FIG. 15 and FIG. 16 show an example of using an optical disc having a recording layer misalignment or warpage. 14 to 16, reference numerals 501 to 503 denote areas, the horizontal axis represents a tilt control value, and the vertical axis represents a focus control value. Further, Fo (0) is a reference focus value stored in advance in the memory of the optical disc apparatus, Ti (0) is a reference tilt value stored in advance in the memory of the optical disc apparatus, and Fo (1) is an optical disc shown in FIG. Is the optimum focus control value when using the optical disc, and Fo (2) is the optimum focus control value when using the optical disc shown in FIG.

  Depending on the combination of the focus control value and the tilt control value, there are a combination that does not deviate the focus servo and a combination that deviates the focus servo. That is, there are combinations that allow focus control and combinations that make focus control difficult.

  FIG. 14 to FIG. 16 show such combinations. In the range from the region 501 to the region 503, the focus control is possible. In the region outside the region 501 to the region 503, the focus control is difficult. A plurality of circular areas in the areas 501 to 503 are contour lines that indicate the focus servo enabling status, and the optimum combination of the focus control reference value and the tilt control reference value for the optical disc becomes closer to the center.

  When an ideal optical disc is used, the relationship between the focus control value capable of focus control and the tilt control value is as shown in FIG. 14, so the reference tilt value Ti (0) and the reference focus value Fo (0) are used as the reference. Focus control is performed as a value. In this case, the reference tilt value Ti (0) and the reference focus value Fo (0) are the same as those stored in advance in the memory 13 of the optical disc apparatus.

  However, in the case of using an optical disc having a recording layer misalignment or warpage, the relationship between the focus control value and the tilt control value capable of focus control depending on the state becomes as shown in FIG. Or something like that. In this case, the focus control values Fo (1) and Fo (2) are different from the focus value Fo (0) stored in advance in the memory 13 of the optical disc apparatus.

Therefore, a plurality of test data was recorded while changing the reference value of the focus control according to the state of the optical disk to be used, and the test data was reproduced and used for recording the test data by performing a certain check process. The condition that the recording quality of the optical disk to be used is the best is selected from the conditions to improve the recording quality of the optical disk.
JP 2006-216115 A

  However, when using an optical disc with large displacement and warping of the recording layer, focus control for reproducing the test data recorded due to the displacement and warpage cannot be performed, and all of the plurality of recorded test data cannot be reproduced. there were. In this case, a part of the information obtained by reproducing the recorded test data is missing and the process of calculating the optimum focus control reference value cannot be performed normally, and the optimum focus control value cannot obtain sufficient accuracy, or There has been a problem that the process of calculating the optimum focus control reference value itself is interrupted due to the lack of part of the information obtained by reproducing the test data, and the optimum focus control reference value cannot be calculated.

  The present invention has been made to solve the above-described problems, and is optimal for an optical disc to be used in consideration of the deviation and warpage even when an optical disc having a large recording layer displacement and warpage is used. An object of the present invention is to provide an optical disc apparatus capable of calculating the position of an objective lens and a focus control method thereof.

  The present invention has been made to solve the above-described problems, and includes a focus error signal generation unit that generates a focus error signal based on reflected light from an optical disc, a servo processing unit that performs focus control, and a focus control signal. Storage means for storing a reference focus value serving as a reference; and control means for generating a first correction focus value obtained by adding a predetermined value to the reference focus value and a second correction focus value obtained by subtracting the predetermined value from the reference focus value. The control means records test data based on the reference focus value, and generates a positive-side amplitude amount and a negative-side amplitude amount with respect to the reference voltage of the focus error signal generated when the test data is reproduced. Based on the ratio, the test is performed using any one of the reference focus value, the first correction focus value, and the second correction focus value. An optical disk apparatus characterized by determining whether to record data.

  The present invention also stores a reference focus value that serves as a reference for focus control, and generates a first corrected focus value obtained by adding a predetermined value to the reference focus value and a second corrected focus value obtained by subtracting the predetermined value from the reference focus value. A focus control method that records test data based on a reference focus value, and generates a positive error amount and a negative amplitude amount with respect to a reference voltage of a focus error signal generated when the test data is reproduced. A focus control method for an optical disc apparatus, which determines whether to record test data using any one of a reference focus value, a first correction focus value, and a second correction focus value based on a ratio. .

  According to the above configuration, the control unit records test data based on the reference focus value and reproduces the test data, and the positive amplitude amount and the negative amplitude amount relative to the reference voltage of the focus error signal generated when the test data is reproduced. A plurality of test data is recorded by determining whether to record the test data using any one of the reference focus value, the first correction focus value, and the second correction focus value based on the ratio to the amplitude amount. In the process of calculating the optimum focus control reference value for the optical disc, the test data recorded after the test recording with the reference focus value cannot be controlled because the focus control cannot be performed and the test data cannot be reproduced. The optimal focus control reference value is calculated by missing part of the information obtained by playing Processing to calculate the optimum focus control reference value because the optimum focus control reference value cannot be obtained with sufficient accuracy, or some of the information obtained by reproducing the recorded test data is missing The interruption of itself can be avoided. As a result, an optical disc apparatus capable of calculating the optimum position of the objective lens for the optical disc to be used in consideration of the deviation and warpage even when using an optical disc with a large positional deviation and warpage of the recording layer, and its A focus control method can be realized.

  Further, based on the ratio of the positive amplitude amount and the negative amplitude amount with respect to the reference voltage of the focus error signal generated when recording the test data based on the reference focus value and reproducing the test data, Optimal focus control reference for an optical disc by recording a plurality of test data by determining whether to record the test data using any one of the reference focus value, the first correction focus value, and the second correction focus value In the process of calculating the value, the number of test recordings after the test recording with the reference focus value is determined from the information obtained by reproducing the test data recorded with the reference focus value. The accuracy of calculating the optimum focus control reference value can be improved, and an improvement in accuracy can be expected. There it is possible to eliminate the test recording. As a result, the accuracy of calculating the optimum focus control reference value according to the individual status of the optical disc to be used is improved, and test recordings that cannot be expected to improve accuracy are also eliminated, so that the optimum focus according to the individual status of the optical disc to be used is eliminated. An optical disc apparatus capable of minimizing the time taken to calculate the focus control reference value and the focus control thereof can be realized while increasing the accuracy of calculating the control reference value.

  According to the first aspect of the present invention, a focus error signal generating unit that generates a focus error signal based on reflected light from an optical disc, a servo processing unit that performs focus control, and a reference focus value that serves as a reference for focus control are stored. Storage means; and control means for generating a first corrected focus value obtained by adding a predetermined value to the reference focus value and a second corrected focus value obtained by subtracting the predetermined value from the reference focus value. The test data is recorded based on the value, and based on the ratio of the positive amplitude amount and the negative amplitude amount to the reference voltage of the focus error signal generated when reproducing the test data, the reference focus value, It is determined whether to record test data using either the first correction focus value or the second correction focus value. It is characterized in. The control means records the test data based on the reference focus value, and based on the ratio between the positive amplitude amount and the negative amplitude amount with respect to the reference voltage of the focus error signal generated when the test data is reproduced. By determining whether the test data is to be recorded using any one of the reference focus value, the first correction focus value, and the second correction focus value, the optimum focus of the optical disc is recorded by recording a plurality of test data. In the process of calculating the control reference value, since the test recording after the test recording with the reference focus value cannot be controlled and the test data cannot be reproduced, no test recording is performed, so one piece of information obtained by reproducing the recorded test data. The process of calculating the optimum focus control reference value due to missing parts cannot be performed normally, and the optimum focus Can be avoided your reference value is not obtained a sufficient accuracy, or the processing itself missing unexpected information when reproducing the recorded test data for calculating an optimum focus control reference value occur is interrupted. As a result, an optical disk device that can calculate the optimum objective lens position for the optical disk to be used is taken into account even when using an optical disk with large displacement and warpage of the recording layer. it can. Further, based on the ratio of the positive amplitude amount and the negative amplitude amount with respect to the reference voltage of the focus error signal generated when recording the test data based on the reference focus value and reproducing the test data, Optimal focus control reference for an optical disc by recording a plurality of test data by determining whether to record the test data using any one of the reference focus value, the first correction focus value, and the second correction focus value In the process of calculating the value, the number of test recordings after the test recording with the reference focus value is determined from the information obtained by reproducing the test data recorded with the reference focus value. The accuracy of calculating the focus control reference value can be improved. The test recording can be eliminated. As a result, it is possible to realize an optical disc apparatus capable of minimizing the time required to calculate the focus control reference value while improving the accuracy of calculating the focus control reference value according to the individual situation of the optical disc to be used.

  According to the second aspect of the present invention, the control means records the test data based on the reference focus value, and the amplitude amount on the positive side and the negative side with respect to the reference voltage of the focus error signal generated when reproducing the test data. When the ratio to the amplitude amount is equal, the test data is recorded using only the reference focus value without using the first correction focus value and the second correction focus value. Thus, in the process of calculating the optimum focus control reference value of the optical disc by recording a plurality of test data, the focus control reference value corresponding to the individual status of the optical disc to be used is calculated only by test recording with the reference focus value. Because it is judged that sufficient information was obtained, test recording after the test recording with the reference focus value is stopped, so when calculating the optimum focus control reference value according to the individual situation to be used, improvement in accuracy cannot be expected Test records can be eliminated. As a result, when the optimum focus control reference value corresponding to the individual situation to be used is calculated, test recordings that cannot be expected to improve accuracy are eliminated, so that the time taken to calculate the focus control reference value can be minimized.

  According to a third aspect of the present invention, when the difference between the positive-side amplitude amount and the negative-side amplitude amount is less than a predetermined amount, the control means has the same ratio between the positive-side amplitude amount and the negative-side amplitude amount. It is characterized by judging. As a result, the control means increases the discrimination accuracy when discriminating the ratio between the positive amplitude and the negative amplitude of the focus error signal, so the optimum focus control reference value corresponding to the individual situation of the optical disk to be used is calculated. It is possible to accurately determine whether or not sufficient information has been obtained.

  According to the fourth aspect of the present invention, the control means records the test data based on the reference focus value, and the amplitude of the positive side with respect to the reference voltage of the focus error signal generated when reproducing the test data is negative. When the amplitude amount is larger, the test data is recorded using the first corrected focus value instead of the reference focus value. Thereby, in the process of calculating the optimum focus control reference value of the optical disc by recording a plurality of test data, it is determined that the test recording by the reference focus value is a condition away from the optimum recording condition, and further from the optimum recording condition. Since the test recording using the second corrected focus value that is expected to be separated is not performed, focus control cannot be performed when the recorded test data is reproduced, and the recorded test data cannot be reproduced with low probability. Some of the information obtained by reproducing the test data is missing and the process of calculating the optimum focus control reference value cannot be performed normally, and the optimum focus control reference value cannot obtain sufficient accuracy, or recorded test data When an image is played back, an unexpected loss of information occurs, and the process of calculating the optimum focus control reference value is Possible to avoid. As a result, an optical disk device that can calculate the optimum objective lens position for the optical disk to be used is taken into account even when using an optical disk with large displacement and warpage of the recording layer. it can.

  According to the fifth aspect of the present invention, the control means determines that the positive amplitude amount is larger than the negative amplitude amount when the difference between the positive amplitude amount and the negative amplitude amount is equal to or larger than a predetermined amount. It is characterized by. As a result, the control means increases the determination accuracy when determining that the positive amplitude of the focus error signal is larger than the negative amplitude, so whether or not it is necessary to perform test recording using the second corrected focus value. Can be accurately determined.

  According to the sixth aspect of the present invention, test data is recorded based on the reference focus value, and the positive amplitude amount with respect to the reference voltage of the focus error signal generated when reproducing the test data is greater than the negative amplitude amount. If it is smaller, the test data is recorded using the second corrected focus value instead of the reference focus value. Thereby, in the process of calculating the optimum focus control reference value of the optical disc by recording a plurality of test data, it is determined that the test recording by the reference focus value is a condition away from the optimum recording condition, and further from the optimum recording condition. Since the test recording using the first corrected focus value that is expected to be separated is not performed, the focus control cannot be performed when the recorded test data is reproduced, and the probability that the recorded test data cannot be reproduced is kept low. Some of the information obtained by reproducing the test data is missing and the process of calculating the optimum focus control reference value cannot be performed normally, and the optimum focus control reference value cannot obtain sufficient accuracy, or recorded test data When an image is played back, an unexpected loss of information occurs, and the process of calculating the optimum focus control reference value is Possible to avoid. As a result, an optical disk device that can calculate the optimum objective lens position for the optical disk to be used is taken into account even when using an optical disk with large displacement and warpage of the recording layer. it can.

  According to the seventh aspect of the present invention, the control means determines that the positive amplitude amount is smaller than the negative amplitude amount when the difference between the positive amplitude amount and the negative amplitude amount is equal to or greater than a predetermined amount. It is characterized by. As a result, the control means increases the determination accuracy when determining that the positive amplitude of the focus error signal is smaller than the negative amplitude, so whether or not it is necessary to perform test recording using the first corrected focus value. Can be accurately determined.

  According to an eighth aspect of the present invention, there is provided a focus error signal generating means for generating a focus error signal based on reflected light from an optical disc, a servo processing means for performing focus control and tilt control, and a first reference serving as a reference for focus control. Storage means for storing the focus value, the second reference focus value, and the first reference tilt value and the second reference tilt value, which serve as a reference for tilt control, and a first correction focus obtained by adding a predetermined value to the first reference focus value A second corrected focus value obtained by subtracting a predetermined value from the value and the first reference focus value is generated, and the predetermined value is subtracted from the third corrected focus value obtained by adding the predetermined value to the second reference focus value and the second reference focus value. Control means for generating a fourth corrected focus value, wherein the control means is a set of a first reference focus value and a first reference tilt value. The first reference focus is recorded based on the ratio of the positive amplitude amount and the negative amplitude amount to the reference voltage of the focus error signal generated when the test data is recorded based on the alignment and reproduced. Whether to record test data using any one of the value, the first correction focus value, and the second correction focus value, and tests based on the combination of the second reference focus value and the second reference tilt value Based on the ratio of the positive and negative amplitudes to the reference voltage of the focus error signal generated when recording and reproducing the test data, the second reference focus value and the third correction It is characterized in that it is determined whether to record the test data using either the focus value or the fourth corrected focus value. The control means records the test data based on the combination of the first reference focus value and the first reference tilt value, and the amplitude amount on the positive side with respect to the reference voltage of the focus error signal generated when reproducing the test data Based on the ratio of the negative amplitude amount to the negative side, it is determined whether to record the test data using any one of the first reference focus value, the first correction focus value, and the second correction focus value. The test data is recorded based on the combination of the 2 reference focus value and the second reference tilt value, and the positive and negative amplitudes with respect to the reference voltage of the focus error signal generated when the test data is reproduced. Recording test data using any one of the second reference focus value, the third correction focus value, and the fourth correction focus value based on the ratio to the amount In the process of calculating the optimum focus control reference value of the optical disc by recording a plurality of test data by determining whether to perform the test recording or the second reference based on the first reference focus value and the first reference tilt value After the test based on the focus value and the second reference tilt value, focus control or tilt control cannot be performed, and test recording that prevents the test data from being reproduced is not performed, so some information obtained by reproducing the recorded test data is missing Therefore, the process of calculating the optimum focus control reference value cannot be performed normally, and the optimum focus control reference value cannot obtain a sufficient accuracy, or an unexpected loss of information occurs when the recorded test data is played back. It is possible to avoid interruption of the processing itself for calculating the control reference value. As a result, an optical disk device that can calculate the optimum objective lens position for the optical disk to be used is taken into account even when using an optical disk with large displacement and warpage of the recording layer. it can.

  According to the ninth aspect of the present invention, a reference focus value serving as a reference for focus control is stored, a first correction focus value obtained by adding a predetermined value to the reference focus value, and a second correction focus value obtained by subtracting the predetermined value from the reference focus value. Is a focus control method that records test data based on a reference focus value and reproduces the test data, and a positive amplitude and a negative amplitude with respect to a reference voltage of a focus error signal generated when the test data is reproduced. Based on the ratio to the amount, it is determined whether to record the test data using any one of the reference focus value, the first correction focus value, and the second correction focus value. As a result, in the process of calculating the optimum focus control reference value of the optical disc by recording a plurality of test data, the test recording that makes it impossible to control the focus in the test recording after the test recording with the reference focus value and the test data cannot be reproduced. As a result, a part of the information obtained by reproducing the recorded test data is lost and the process of calculating the optimum focus control reference value cannot be performed normally, and the optimum focus control reference value cannot obtain sufficient accuracy. Alternatively, it is possible to avoid interruption of the processing itself for calculating the optimum focus control reference value due to an unexpected loss of information when the recorded test data is reproduced. As a result, the focus of the optical disc apparatus can calculate the optimum position of the objective lens for the optical disc to be used in consideration of the deviation and warpage even when an optical disc having a large positional deviation and warpage of the recording layer is used. A control method can be realized. Further, based on the ratio of the positive amplitude amount and the negative amplitude amount with respect to the reference voltage of the focus error signal generated when recording the test data based on the reference focus value and reproducing the test data, Optimal focus control reference for an optical disc by recording a plurality of test data by determining whether to record the test data using any one of the reference focus value, the first correction focus value, and the second correction focus value In the process of calculating the value, the number of test recordings after the test recording with the reference focus value is determined from the information obtained by reproducing the test data recorded with the reference focus value. The accuracy of calculating the focus control reference value can be improved. The test recording can be eliminated. As a result, it is possible to realize a focus control method for an optical disc apparatus that can minimize the time required to calculate the focus control reference value while improving the accuracy of calculating the focus control reference value according to the individual situation of the optical disc to be used.

  According to the tenth aspect of the present invention, the test data is recorded based on the reference focus value, and the positive amplitude amount and the negative amplitude amount with respect to the reference voltage of the focus error signal generated when the test data is reproduced. When the ratios are equal, the test data is recorded using only the reference focus value without using the first and second corrected focus values. Thus, in the process of calculating the optimum focus control reference value of the optical disc by recording a plurality of test data, the focus control reference value corresponding to the individual status of the optical disc to be used is calculated only by test recording with the reference focus value. Because it is judged that sufficient information was obtained, test recording after the test recording with the reference focus value is stopped, so when calculating the optimum focus control reference value according to the individual situation to be used, improvement in accuracy cannot be expected Test records can be eliminated. As a result, when the optimum focus control reference value corresponding to the individual situation to be used is calculated, test recordings that cannot be expected to improve accuracy are eliminated, so that the time taken to calculate the focus control reference value can be minimized.

  In the invention described in claim 11, when the difference between the positive amplitude amount and the negative amplitude amount is less than a predetermined amount, it is determined that the ratio between the positive amplitude amount and the negative amplitude amount is equal. Features. As a result, the control means increases the discrimination accuracy when discriminating the ratio between the positive amplitude and the negative amplitude of the focus error signal, so the optimum focus control reference value corresponding to the individual situation of the optical disk to be used is calculated. It is possible to accurately determine whether or not sufficient information has been obtained.

  In the invention described in claim 12, the test data is recorded based on the reference focus value, and the positive amplitude amount with respect to the reference voltage of the focus error signal generated when the test data is reproduced is smaller than the negative amplitude amount. If larger, the test data is recorded using the first corrected focus value instead of the reference focus value. As a result, in the process of calculating the optimum focus control reference value of the optical disc by recording a plurality of test data, it is determined that the test recording by the reference focus value is at a position away from the optimum position and further away from the optimum position. Since test recording using the expected second corrected focus value is not performed, focus control cannot be performed when the recorded test data is reproduced, and the probability that the recorded test data cannot be reproduced is suppressed to a low level. The process of calculating the optimum focus control reference value cannot be performed normally due to the loss of part of the information obtained by reproducing the image, and the optimum focus control reference value cannot obtain sufficient accuracy, or the recorded test data is reproduced. Unexpected information loss occurs and the process of calculating the optimum focus control reference value is interrupted. The can be avoided. As a result, the focus of the optical disc apparatus can calculate the optimum position of the objective lens for the optical disc to be used in consideration of the deviation and warpage even when an optical disc having a large positional deviation and warpage of the recording layer is used. A control method can be realized.

  The invention according to claim 13 is characterized in that when the difference between the positive amplitude amount and the negative amplitude amount is equal to or larger than a predetermined amount, the positive amplitude amount is determined to be larger than the negative amplitude amount. . As a result, the control means increases the determination accuracy when determining that the positive amplitude of the focus error signal is larger than the negative amplitude, so whether or not it is necessary to perform test recording using the second corrected focus value. Can be accurately determined.

  In the fourteenth aspect of the present invention, test data is recorded based on the reference focus value, and the positive amplitude amount with respect to the reference voltage of the focus error signal generated when reproducing the test data is greater than the negative amplitude amount. If it is smaller, the test data is recorded using the second corrected focus value instead of the reference focus value. Thus, in the process of calculating the optimum focus control reference value of the optical disc by recording a plurality of test data, it is determined that the test recording by the reference focus value is a condition away from the optimum condition, and further away from the optimum condition. Since test recording using the expected first corrected focus value is not performed, when the recorded test data is reproduced, focus control cannot be performed and the probability of reproducing the test data is suppressed, and the recorded test data is reproduced. The process of calculating the optimum focus control reference value cannot be performed normally due to lack of some of the obtained information, and the optimum focus control reference value cannot be obtained with sufficient accuracy, or is expected when playing back recorded test data Therefore, it is possible to avoid interruption of the process itself for calculating the optimum focus control reference value due to missing information. As a result, the focus of the optical disc apparatus can calculate the optimum position of the objective lens for the optical disc to be used in consideration of the deviation and warpage even when an optical disc having a large positional deviation and warpage of the recording layer is used. A control method can be realized.

  The invention according to claim 15 is characterized in that when the difference between the positive amplitude amount and the negative amplitude amount is equal to or larger than a predetermined amount, the positive amplitude amount is determined to be smaller than the negative amplitude amount. . As a result, the control means increases the determination accuracy when determining that the positive amplitude of the focus error signal is smaller than the negative amplitude, so whether or not it is necessary to perform test recording using the first corrected focus value. Can be accurately determined.

  According to a sixteenth aspect of the present invention, the first reference focus value and the second reference focus value that serve as a reference for focus control, and the first reference tilt value and the second reference tilt value that serve as a reference for tilt control are stored. A first correction focus value obtained by adding a predetermined value to the first reference focus value and a second correction focus value obtained by subtracting the predetermined value from the first reference focus value are generated, and a third correction obtained by adding the predetermined value to the second reference focus value A focus control method for generating a fourth corrected focus value obtained by subtracting a predetermined value from a focus value and a second reference focus value, and recording test data based on a combination of the first reference focus value and the first reference tilt value Then, based on the ratio between the positive amplitude amount and the negative amplitude amount with respect to the reference voltage of the focus error signal generated when reproducing the test data, It is determined whether to record test data using any one of the reference focus value, the first correction focus value, and the second correction focus value, and based on the combination of the second reference focus value and the second reference tilt value. The second reference focus value, the second reference focus value, and the second reference focus value based on the ratio of the positive amplitude amount and the negative amplitude amount to the reference voltage of the focus error signal generated when the test data is reproduced. It is characterized in that it is determined whether to record the test data using any one of the third correction focus value and the fourth correction focus value. Thus, in the process of calculating the optimum focus control reference value of the optical disc by recording a plurality of test data, the test recording based on the first reference focus value and the first reference tilt value or the second reference focus value and the second Since there is no test recording that prevents focus data or tilt control after the test based on the reference tilt value and test data cannot be replayed, optimal focus control is achieved by missing some of the information obtained by replaying the recorded test data. The process of calculating the reference value cannot be performed normally, and the optimal focus control reference value cannot obtain sufficient accuracy, or when the recorded test data is played back, unexpected loss of information occurs and the optimal focus control reference value is calculated. It is possible to avoid interruption of the processing itself. As a result, the focus of the optical disc apparatus can calculate the optimum position of the objective lens for the optical disc to be used in consideration of the deviation and warpage even when an optical disc having a large positional deviation and warpage of the recording layer is used. A control method can be realized.

(Embodiment 1)
Embodiment 1 of the present invention will be described below with reference to the drawings.

  FIG. 1 is a block diagram of an optical disc apparatus according to Embodiment 1 of the present invention. In FIG. 1, 1 is a light source, 2 is an objective lens, 3 is a lens holder, 4 is an actuator, 4a is a focus adjustment coil, 5 is a quadrant photodetector, 6 is a spindle motor, 7 is a feed motor, and 8 is a focus. Error signal generation circuit, 9 RF signal detection circuit, 10 focus servo circuit, 11 signal measurement circuit, 12 jitter detection circuit, 13 memory, 14 CPU, 15 laser control unit, 16 driver, 50 An optical disk, 100 is an optical head unit, and 200 is a pickup module.

  The pickup module 200 includes a spindle motor 6 that rotates the optical disc 50, an optical head unit 100 that irradiates the optical disc 50 with light and receives reflected light from the optical disc 50, and moves the optical head unit 100 in the radial direction of the optical disc 50. And a feed section provided with a feed motor 7.

  The optical head unit 100 includes a light source 1 that emits light applied to the optical disc 50, an objective lens 2 that condenses the emitted light from the light source 1, a lens holder 3 that holds the objective lens 2 movably, and a lens holder. 3 is provided with an actuator 4 that drives 3 and a quadrant photodetector 5 that receives the reflected light from the optical disk 50 via the objective lens 2.

  The actuator 4 is provided with a focus adjustment coil 4a, a tilt adjustment coil (not shown), a magnet, and the like. By driving a current through the coil, the lens holder 3 is driven in the focus direction and the tilt direction to move the objective lens 2. By doing so, focus adjustment and tilt adjustment are performed.

  The quadrant photodetector 5 receives reflected light from the optical disc 50, generates an electrical signal corresponding to the received light quantity, and outputs the generated electrical signal to a focus error signal generation circuit 8 and an RF signal detection circuit 9 Output to.

  The focus error signal generation circuit 8 generates a focus error signal from the electrical signal input from the quadrant photodetector 5 and outputs the focus error signal to the focus servo circuit 10 and the signal measurement circuit 11. The RF signal detection circuit 9 detects an RF signal from the electrical signal input from the quadrant photodetector 5 and outputs the RF signal to the signal measurement circuit 11 and the jitter detection circuit 12.

  The focus servo circuit 10 determines a current to flow through the focus adjustment coil 4 a provided in the actuator 4 a based on the focus error signal input from the focus error signal generation circuit 8 and outputs the current to the CPU 14. The signal measurement circuit 11 measures the positive-side amplitude amount and the negative-side amplitude amount with respect to the reference voltage of the focus error signal input from the focus error signal generation circuit 8, and outputs the measurement result to the CPU 14. Further, the signal measurement circuit 11 measures the amplitude of the RF signal input from the RF signal detection circuit 9 and outputs it to the CPU 14 as an RF signal amplitude value. The jitter detection circuit 12 detects a jitter component that is a temporal fluctuation of the RF signal input from the RF signal detection circuit 9 and outputs it to the CPU 14 as a jitter value.

  The memory 13 stores a reference focus value as a control reference for focus control and a reference tilt value as a control reference for tilt control, and sends the reference focus value and the reference tilt value to the CPU 14 according to a command from the CPU 14. . The reference focus value and the reference tilt value are those when an ideal optical disk is used. Since an actual optical disk has a recording layer shift or warp, the reference focus value and the reference tilt value are adjusted by the CPU 14 according to the optical disk 50 to be used.

  The CPU 14 receives signals sent from the focus error signal generation circuit 8, the focus servo circuit 10, the signal measurement circuit 11, the memory 13, and the driver 16, and performs arithmetic processing on these signals. (Signal) is sent to each part, and each part is driven and processed to control each part. Since the RF signal amplitude value input from the signal measuring circuit 11 means that the recording quality of information recorded on the optical disc 50 is better as the value is larger, the CPU 14 uses the RF signal amplitude value to apply to the optical disc 50. The recording quality of the recorded test data can be judged. Further, the jitter value input from the signal measurement circuit 11 means that the smaller the value is, the better the recording quality of the information recorded on the optical disc 50 is. Therefore, the CPU 14 records the jitter value on the optical disc 50 using this jitter value. The recording quality of the test data can be judged.

  The laser control unit 15 adjusts the light emission amount of the light source 1 based on the light amount of the reflected light from the optical disc 50 detected by the quadrant light detector 5 so that the light amount applied to the optical disc 50 becomes a predetermined amount.

  The driver 16 drives the spindle motor 6, the laser controller 15, and the focus adjustment coil 4 a according to a command from the CPU 14, rotates the optical disk 50, adjusts the light emission amount of the light source 1, and performs focus control of the objective lens 2. Do.

  In the first embodiment, the focus error signal generation means corresponds to the focus error signal generation circuit 8, the servo processing means corresponds to the focus servo circuit 10, the storage means corresponds to the memory 13, and the control means corresponds to the CPU 14.

  FIG. 2 is a diagram showing a focus error signal generation circuit according to the first embodiment of the present invention. In FIG. 2, 5 is a quadrant photodetector, 5a and 5b are photodetectors, 8 is a focus error signal generation circuit, 8a is a balance circuit, and 8b is a differential circuit.

  The quadrant photodetector 5 is composed of four photodetectors, and a photodetector 5a and a photodetector 5b are formed by combining two predetermined detectors among the four detectors. The photodetector 5a sends a signal corresponding to the positive waveform with respect to the reference voltage of the focus error signal, and the photodetector 5b sends a signal corresponding to the negative waveform with respect to the reference voltage of the focus error signal. Here, the reference voltage refers to the output voltage of the focus error signal when the output signals of the photodetectors 5a and 5b are both 0.

  The signals sent from the photodetector 5a and the photodetector 5b are input to the differential circuit 8b via the balance circuit 8a, where a signal corresponding to a positive waveform with respect to the reference voltage of the focus error signal The focus error signal is generated by performing a differential operation on the signal corresponding to the waveform on the negative side with respect to the reference voltage of the focus error signal.

  FIG. 3 is a diagram showing a focus error signal generated when the test data is reproduced in the first embodiment of the present invention. In FIG. 3, the horizontal axis indicates the amount of displacement (distance) of the objective lens when the focal point is the reference, the vertical axis indicates the voltage, and a1, a2, and a3 are the positive side of the reference voltage of the focus error signal. The amount of amplitude of the waveform is shown, and b1, b2, and b3 show the amount of amplitude of the negative waveform with respect to the reference voltage of the focus error signal. FIG. 3A shows a case where the ratio between the amplitude amount of the positive waveform and the amplitude amount of the negative waveform with respect to the reference voltage of the focus error signal is equal (a1 = b1), and FIG. FIG. 3C shows a case where the positive amplitude amount with respect to the reference voltage of the focus error signal is larger than the negative amplitude amount (a2> b2). FIG. 3C shows that the positive amplitude amount with respect to the reference voltage of the focus error signal is negative. The case where the amplitude amount is smaller than that on the side (a3 <b3) is shown. The focus error signal is output in one of the patterns shown in FIGS. 3A to 3C according to the position shift or warpage of the recording layer of the optical disc.

  The closer the focus control reference value used when recording data to the optical disc 50 is to the optimum focus control value of the optical disc 50 being used, the more positive the reference voltage of the focus error signal generated when data is reproduced. The difference between the amplitude amount and the negative amplitude amount has a characteristic of decreasing.

  The operation of the CPU 14 in Embodiment 1 of the present invention using this will be described.

  The CPU 14 uses the reference focus value input from the memory 13 to drive the actuator 4 via the driver 16 and records test data in the test recording area of the optical disc 50. Thereafter, the test data is reproduced, a focus error signal is generated by the focus error signal generation circuit 8, and a positive amplitude amount and a negative amplitude amount with respect to the reference voltage of the focus error signal are measured by the signal measurement circuit 11. . Based on the measurement result, a first correction focus value obtained by adding a predetermined value to the reference focus value and a second correction focus value obtained by subtracting the predetermined value from the reference focus value input from the memory 13 are calculated.

  In the first embodiment, the first corrected focus value and the second corrected focus value are calculated after the test data is recorded using the reference focus value. However, the first corrected focus value and the second corrected focus value are calculated. The correction focus value may be calculated in advance before recording the test data using the reference focus value.

  At this time, as shown in FIG. 3A, when the ratio of the positive amplitude amount and the negative amplitude amount to the reference voltage of the focus error signal is equal, the reference focus value used when recording the test data Is determined to be appropriate for the optical disc 50 to be used. Then, it is determined that sufficient information has been obtained to calculate the focus control reference value according to the individual status of the optical disc 50 to be used, and the test recording after the test recording with the reference focus value is stopped. Thereby, when calculating the focus control reference value according to the individual situation to be used, test recordings that cannot be expected to improve accuracy are eliminated, so that the time required for calculating the focus control reference value can be minimized. Here, even when the difference between the positive amplitude amount and the negative amplitude amount with respect to the reference voltage of the focus error signal is less than a predetermined amount, it is determined that the ratio between the positive amplitude amount and the negative amplitude amount is equal. As a result, the discrimination accuracy when the CPU 14 discriminates the ratio of the positive side amplitude and the negative side amplitude of the focus error signal is improved, so that the control reference value for the focus control corresponding to the individual situation to be used can be calculated. It is possible to accurately determine whether sufficient information has been obtained. The predetermined amount in the first embodiment is 20% of the focus error signal amplitude amount.

  Further, as shown in FIG. 3B, when the positive amplitude amount with respect to the reference voltage of the focus error signal is larger than the negative amplitude amount, the reference focus value used for recording the test data is the optical disc to be used. 50 is not appropriate, and it is determined that it is located toward the end of the distribution indicating the relationship between the focus value and the tilt value for which focus control is possible. Since the test recording using the reference focus value is determined to be a condition away from the optimum recording condition, the test recording using the second corrected focus value that is expected to be further away from the optimum recording condition is not performed. The focus control cannot be performed when data is played back, and the probability that the recorded test data cannot be played back is kept low, and some of the information obtained by playing back the recorded test data is lost, and the optimal focus control reference value is calculated. The process of calculating the optimal focus control reference value is not possible when the optimal focus control reference value cannot obtain sufficient accuracy, or when the recorded test data is reproduced, an unexpected loss of information occurs. The interruption can be avoided. Here, when the difference between the positive-side amplitude amount and the negative-side amplitude amount with respect to the reference voltage of the focus error signal is a predetermined value or more, by determining that the positive-side amplitude amount is larger than the negative-side amplitude amount, The CPU 14 increases the determination accuracy when determining that the positive-side amplitude of the focus error signal is larger than the negative-side amplitude, so that it is accurate to determine whether or not it is necessary to perform test recording using the second corrected focus value. Can be done well.

  Further, as shown in FIG. 3C, when the positive-side amplitude amount with respect to the reference voltage of the focus error signal is smaller than the negative-side amplitude amount, the test data is recorded as in FIG. It is determined that the reference focus value used in the above is not appropriate for the optical disc 50 to be used and is positioned closer to the end of the distribution indicating the relationship between the focus value and the tilt value capable of focus control. Since the test recording using the reference focus value is determined to be a condition away from the optimum recording condition, the test recording using the first corrected focus value that is expected to be further away from the optimum recording condition is not performed. The focus control cannot be performed when data is played back, and the probability that the recorded test data cannot be played back is kept low, and some of the information obtained by playing back the recorded test data is lost, and the optimal focus control reference value is calculated. The optimal focus control reference value cannot be obtained with sufficient accuracy, or when the test data is reproduced, an unexpected loss of information occurs and the process of calculating the optimal focus control reference value is interrupted. You can avoid that. Here, when the difference between the positive amplitude amount and the negative amplitude amount with respect to the reference voltage of the focus error signal is a predetermined value or more, by determining that the positive amplitude amount is smaller than the negative amplitude amount, Since the CPU 14 increases the determination accuracy when determining that the positive amplitude of the focus error signal is smaller than the negative amplitude, it is accurate to determine whether or not it is necessary to perform test recording using the first corrected focus value. Can be done well.

  4 to 6 are diagrams showing a method for selecting a focus control reference value according to the first embodiment of the present invention, and show a range of combinations of focus control values and tilt control values capable of focus control. In either case, an example of using an optical disk having a recording layer misalignment or warpage is shown. 4 to 6, reference numerals 401 to 403 denote areas, the horizontal axis indicates the tilt control value, and the vertical axis indicates the focus control value. Further, Fo (G) is a reference focus value stored in advance in the memory of the optical disk apparatus, Ti (0) is a reference tilt value stored in advance in the memory of the optical disk apparatus, and Fo (P1) is an optical disk shown in FIG. Is the optimum focus control reference value when using the optical disc, Fo (P2) is the optimum focus control reference value when using the optical disc shown in FIG. 5, and Fo (P3) is the optimum when using the optical disc shown in FIG. Focus control reference value.

  Depending on the combination of the focus control value and the tilt control value, there are a combination that does not deviate the focus servo and a combination that deviates the focus servo. That is, there are combinations that allow focus control and combinations that make focus control difficult.

  FIG. 4 to FIG. 6 show the combinations. The combinations in the regions 401 to 403 are focus controllable, and the regions outside the regions 401 to 403 are difficult to focus control. A plurality of ellipse areas in the areas 401 to 403 are contour lines indicating the focus servo enable status, and the optimum combination of the focus control reference value and the tilt control reference value for the optical disc becomes closer to the center.

  The optical disk apparatus stores a reference focus value Fo (G) in the memory 13 when the objective lens 2 is focused on the optical disk 50. With the reference focus value Fo (G) as the center, the focus control reference value is changed in accordance with the state of the optical disc to improve the recording quality. Since the position of the recording layer of the optical disc and the warp of the optical disc cannot be measured directly in actual use, a plurality of test data is recorded while changing the position of the objective lens on the optical disc to be used, and the recorded test data By checking the RF signal amplitude value or jitter value, the conditions for recording quality of the optical disc to be used are selected from the conditions used for recording the test data, and the position of the objective lens is determined. ing.

  The test data is recorded in the first embodiment by the reference focus value Fo (G) stored in the memory 13 and the first corrected focus value Fo (A) obtained by adding a predetermined value to the reference focus value Fo (G). Then, a second corrected focus value Fo (B) obtained by subtracting a predetermined value from the reference focus value Fo (G) is calculated, and a focus value for recording test data is determined from these three focus values.

  Which of the three focus values is selected depends on the state of the optical disc 50 to be used, and will be described in the following order.

  First, there is a case where there is almost no displacement or warping of the recording layer in the optical disc to be used. In this case, the relationship between the focus control value and the tilt control value that provides the best recording quality is, for example, a point P1 shown in FIG. The method for determining the focus control value for recording the test data at this time is as follows.

  The CPU 14 sets the reference focus value Fo (G) stored in the memory 13 as a focus control reference value, and the CPU 14 sets the reference tilt value Ti (0) stored in the memory 13 as a reference value for tilt control. Record test data. At this time, test data is recorded with the reference focus value Fo (G) indicated by the point G for the optical disc having the characteristics shown in FIG.

  In this case, the focus error signal generated when the test data is reproduced is substantially the same as that shown in FIG. 3A, and the ratio between the positive amplitude amount and the negative amplitude amount of the focus error signal is Therefore, it is determined that the focus value Fo (G) indicated by the point G is substantially the same value as the focus value Fo (P1) indicated by the point P1. Then, the test data is recorded by the first corrected focus value Fo (A) indicated by the point A and the test data is not recorded by the second corrected focus value Fo (B) indicated by the point B, and the reference focus value indicated by the point G is obtained. Subsequent processing is performed using only Fo (G).

  As described above, the test data is recorded using only the reference focus value Fo (G) without using the first correction focus value Fo (A) and the second correction focus value Fo (B). In the process of calculating the optimum focus control reference value of the optical disc by recording data, the focus control reference value corresponding to the individual situation of the optical disc 50 to be used is calculated only by test recording with the reference focus value Fo (G). Since the test recording after the test recording with the reference focus value Fo (G) is canceled because it is determined that sufficient information has been obtained, the accuracy is improved when calculating the optimum focus control reference value according to the individual situation to be used Can eliminate test records that cannot be expected. As a result, when the optimum focus control reference value corresponding to the individual situation to be used is calculated, test recordings that cannot be expected to improve accuracy are eliminated, so that the time taken to calculate the focus control reference value can be minimized.

  Further, when the difference between the positive amplitude amount and the negative amplitude amount of the focus error signal is less than a predetermined amount, the CPU 14 determines that the ratio between the positive amplitude amount and the negative amplitude amount is equal. As a result, the CPU 14 increases the determination accuracy when determining the ratio between the positive amplitude and the negative amplitude of the focus error signal, so that the optimum focus control reference value corresponding to the individual condition of the optical disk 50 to be used is calculated. It is possible to accurately determine whether sufficient information has been obtained. Here, the predetermined value in the present embodiment is 20% of the amplitude value of the entire focus error signal.

  Next, there is a case where the recording layer is misaligned or warped in the optical disk to be used. The relationship between the focus value and the tilt value that provides the best recording quality is, for example, a point P2 shown in FIG. 5 and a point P3 shown in FIG. The method for determining the focus value for recording the test data at this time is as follows.

  In the case of FIG. 5, the CPU 14 sets the reference focus value Fo (G) stored in the memory 13 as the focus control reference value, and sets the reference tilt value Ti (0) stored in the memory 13 as the tilt control reference value. Record the test data. At this time, test data is recorded with the reference focus value Fo (G) indicated by the point G for the optical disc having the characteristics shown in FIG. In this case, the focus error signal generated when the test data is reproduced is as shown in FIG. 3B, and the positive amplitude amount of the focus error signal is larger than the negative amplitude amount. Is determined to be different from the focus value Fo (P2) indicated at the point P2. At the same time, when the test data is recorded with the second corrected focus value Fo (B) shown at the point B, it is determined that the positive amplitude amount of the focus error signal is further larger than the negative amplitude amount. Then, the subsequent processing is performed using the first corrected focus value Fo (A) indicated by the point A without recording the test data using the second corrected focus value Fo (B) indicated by the point B.

  As described above, the test data is recorded by using the first corrected focus value Fo (A) instead of the second corrected focus value Fo (B) and using the first corrected focus value Fo (A). In the process of calculating the optimum focus control reference value of the optical disc by recording the test data, it is determined that the test recording with the reference focus value Fo (G) is a condition away from the optimum recording condition, and further away from the optimum recording condition. Since the test recording using the second corrected focus value Fo (B) that is expected to be performed is not performed, the focus control cannot be performed when the recorded test data is reproduced, and the probability that the recorded test data cannot be reproduced is kept low. When the recorded test data is reproduced, some of the information obtained is lost and the process of calculating the optimum focus control reference value is performed normally. It not, can be avoided optimum focus control reference value is not obtained a sufficient accuracy, or the processing itself missing unexpected information to calculate the optimum focus control reference value occurs when reproducing the test data interruption.

  Further, when the difference between the positive amplitude amount and the negative amplitude amount is equal to or larger than a predetermined amount, the CPU 14 determines that the positive amplitude amount is larger than the negative amplitude amount, whereby the CPU 14 determines the focus error signal. The discrimination accuracy when discriminating that the positive-side amplitude is larger than the negative-side amplitude is improved, so that it is accurately determined whether or not the test recording using the second corrected focus value Fo (B) is necessary. It can be carried out. Here, the predetermined value in the present embodiment is 20% of the amplitude value of the entire focus error signal.

  Next, in the case of FIG. 6, the CPU 14 sets the reference focus value Fo (G) stored in the memory 13 as the focus control reference value, and uses the reference tilt value Ti (0) stored in the memory 13 as the reference for tilt control. Set the value and record the test data. At this time, for the optical disc having the characteristics shown in FIG. In this case, the focus error signal generated when reproducing the test data is as shown in FIG. 3C, and the positive amplitude amount of the focus error signal is smaller than the negative amplitude amount. Is determined to be different from the focus value Fo (P3) indicated at the point P3. At the same time, when the test data is recorded with the first corrected focus value Fo (A) indicated by the point A, it is determined that the positive amplitude amount of the focus error signal is further smaller than the negative amplitude amount. Then, the subsequent processing is performed using the second corrected focus value Fo (B) indicated by the point B without recording the test data by the first corrected focus value Fo (A) indicated by the point A.

  As described above, the test data is recorded by using the second correction focus value Fo (B) instead of the first correction focus value Fo (A) and using the second correction focus value Fo (B) instead of the reference focus value Fo (G). In the process of calculating the optimum focus control reference value of the optical disc by recording the test data, it is determined that the test recording with the reference focus value Fo (G) is a condition away from the optimum recording condition, and further away from the optimum recording condition. Since the test recording using the first corrected focus value Fo (A) that is expected to be performed is not performed, the focus control cannot be performed when the recorded test data is reproduced, and the probability that the recorded test data cannot be reproduced is kept low. When the recorded test data is reproduced, some of the information obtained is lost and the process of calculating the optimum focus control reference value is performed normally. It not, can be avoided optimum focus control reference value is not obtained a sufficient accuracy, or the processing itself missing unexpected information to calculate the optimum focus control reference value occurs when reproducing the test data interruption.

  Further, when the difference between the positive amplitude amount and the negative amplitude amount is equal to or larger than a predetermined amount, the CPU 14 determines that the positive amplitude amount is smaller than the negative amplitude amount, whereby the CPU 14 determines the focus error signal. The discrimination accuracy when discriminating that the positive-side amplitude is larger than the negative-side amplitude is improved, so that it is accurately determined whether or not the test recording using the first corrected focus value Fo (A) is necessary. It can be carried out. Here, the predetermined value in the present embodiment is 20% of the amplitude value of the entire focus error signal.

  FIG. 7 is a flowchart showing the focus control method in Embodiment 1 of the present invention.

  When the optical disk 50 is loaded in the optical disk apparatus, the CPU 14 rotates the spindle motor 6 via the driver 15 and causes the light source 1 to emit light via the driver 16 and the laser controller 15 (S1). Next, the CPU 14 reads the reference tilt value Ti (0) and the reference focus value Fo (G) from the memory 13 (S2), and obtains test data based on the reference tilt value Ti (0) and the reference focus value Fo (G). Record (S3). Thereafter, the CPU 14 reproduces the test data recorded based on the reference tilt value Ti (0) and the reference focus value Fo (G) (S4), and generates a focus error signal by the focus error signal generation circuit 8 based on the reproduction signal. (S5). The generated focus error signal is sent to the signal measurement circuit 11, and the signal measurement circuit 11 compares the positive-side amplitude amount and the negative-side amplitude amount with respect to the reference voltage of the focus error signal (S6).

  At this time, the ratio of the positive amplitude amount to the negative amplitude amount with respect to the reference voltage of the focus error signal is compared, and as shown in FIG. 3A, the positive amplitude amount and the negative amplitude amount are Are equal (S7), it is determined that the reference focus value Fo (G) used for recording the test data is appropriate for the mounted optical disc, and the focus according to the individual situation of the optical disc to be used is determined. It is determined that sufficient information has been obtained to calculate the control reference value, and subsequent test data is not recorded (S8). Thereby, when calculating the focus control reference value according to the individual situation to be used, test recordings that cannot be expected to improve accuracy are eliminated, so that the time required for calculating the focus control reference value can be minimized.

  In addition, the ratio of the positive amplitude amount to the negative amplitude amount with respect to the reference voltage of the focus error signal is compared, and the ratio of the positive amplitude amount to the negative amplitude amount is not equal, and the positive amplitude amount. Is larger than the negative amplitude amount (S9), a first corrected focus value Fo (A) obtained by adding a predetermined value to the reference focus value Fo (G) is calculated (S10). The reference focus value Fo (G) used for recording the test data is not appropriate for the optical disc to be used, and is closer to the end of the distribution indicating the relationship between the focus control value and the tilt control value that can be controlled. The second corrected focus value Fo (B, which is predicted to be further away from the optimum recording condition by judging that the test recording is based on the reference focus value Fo (G) is at a position away from the optimum recording condition. The test recording is performed with a combination of the reference tilt value Ti (0) and the first corrected focus value Fo (A) that is expected to approach the optimum recording condition without performing the test recording using () (S11). As a result, the test using the second corrected focus value Fo (B) that is predicted to be further away from the optimum recording condition by judging that the test recording with the reference focus value Fo (G) is away from the optimum recording condition. Since recording is not performed, focus control cannot be performed when the recorded test data is reproduced, and the probability that the recorded test data cannot be reproduced is kept low, and a part of the information obtained by reproducing the recorded test data is missing. Therefore, the process of calculating the optimum focus control reference value cannot be performed normally, and the optimum focus control reference value cannot obtain a sufficient accuracy, or an unexpected loss of information occurs when the recorded test data is played back. It is possible to avoid interruption of the processing itself for calculating the control reference value.

  In addition, the ratio of the positive amplitude amount to the negative amplitude amount with respect to the reference voltage of the focus error signal is compared, and the ratio of the positive amplitude amount to the negative amplitude amount is not equal, and the positive amplitude amount. Is not larger than the negative-side amplitude amount, and the positive-side amplitude amount is smaller than the negative-side amplitude amount (S12), the second corrected focus value Fo () obtained by subtracting a predetermined value from the reference focus value Fo (G) B) is calculated (S13). Then, the reference focus value Fo (G) used for recording the test data is not appropriate for the optical disc 50 to be used, and is positioned toward the end of the distribution indicating the relationship between the focus value and the tilt value capable of focus control. The first corrected focus value Fo (A) that is predicted to be further away from the optimum recording condition by judging that the test recording with the reference focus value Fo (G) is at a position away from the optimum recording condition. Test data is recorded with a combination of the reference tilt value Ti (0) and the second corrected focus value Fo (B) that is expected to approach the optimum recording condition without performing test recording using S (S14). As a result, the test using the first corrected focus value Fo (A) that is predicted to be further away from the optimum recording condition by judging that the test recording with the reference focus value Fo (G) is away from the optimum recording condition. Since recording is not performed, focus control cannot be performed when the recorded test data is reproduced, and the probability that the recorded test data cannot be reproduced is kept low, and a part of the information obtained by reproducing the recorded test data is missing. Therefore, the process of calculating the optimum focus control reference value cannot be performed normally, and the optimum focus control reference value cannot obtain a sufficient accuracy, or an unexpected loss of information occurs when the recorded test data is played back. It is possible to avoid interruption of the processing itself for calculating the control reference value.

  As described above, in the process of calculating the optimum focus control reference value of the optical disc by recording a plurality of test data, the focus control cannot be performed in the test recording after the test recording with the reference focus value Fo (G). Since the test recording that prevents the data from being reproduced is not performed, a part of the information obtained by reproducing the recorded test data is lost, and the process for calculating the optimum focus control reference value cannot be performed normally. It can be avoided that the process itself for calculating the optimum focus control reference value is interrupted due to lack of sufficient accuracy or lack of a part of information obtained by reproducing the recorded test data. As a result, an optical disc apparatus capable of calculating the optimum position of the objective lens for the optical disc to be used in consideration of the deviation and warpage even when using an optical disc with a large positional deviation and warpage of the recording layer, and its A focus control method can be realized.

  Further, the ratio of the positive amplitude amount to the negative amplitude amount with respect to the reference voltage of the focus error signal generated when the test data is recorded based on the reference focus value Fo (G) and reproduced. Based on the reference focus value Fo (G), the first correction focus value Fo (A), and the second correction focus value Fo (B). In the process of calculating the optimum focus control reference value of the optical disc by recording a plurality of test data, the reference focus value Fo (G (G) is obtained from information obtained by reproducing the test data recorded with the reference focus value Fo (G). ), The number of test recordings after the test recording is determined, so the optimum focus according to the individual situation of the optical disk to be used Can improve the accuracy of calculating the control reference value, it can be eliminated test recording that are not expected to be accuracy together. As a result, the accuracy of calculating the optimum focus control reference value according to the individual situation of the optical disc 50 to be used is improved, and test recording that cannot be expected to improve the accuracy is eliminated. An optical disc apparatus capable of minimizing the time taken to calculate the focus control reference value and the focus control thereof can be realized while improving the accuracy of calculating the optimum focus control reference value.

(Embodiment 2)
In the second embodiment of the present invention, a method using a combination of a first reference focus value and a first reference tilt value and a combination of a second reference focus value and a second reference tilt value will be described with reference to the drawings.

  The overall configuration of the optical disc apparatus according to the second embodiment is the same as that of the first embodiment shown in FIGS. Further, the focus error signal generated when reproducing the test data in the second embodiment is the same as that of the first embodiment shown in FIG. The pattern is output in any one of FIGS. 3A to 3C.

  The focus error signal generating means in the second embodiment corresponds to the focus error signal generating circuit 8 shown in FIG. 1, the servo processing means corresponds to the focus servo circuit 10, the storage means corresponds to the memory 13, and the control means corresponds to the CPU 14.

  FIGS. 8 to 10 are diagrams showing a method for selecting a focus control reference value according to the second embodiment of the present invention, and show a range of combinations of focus control values and tilt control values capable of focus control. In either case, an example of using an optical disk having a recording layer misalignment or warpage is shown. 8 to 10, reference numerals 404 to 406 denote areas, the horizontal axis represents a tilt control value, and the vertical axis represents a focus control value. Further, Fo (H) is a first reference focus value stored in advance in the memory of the optical disc apparatus, Ti (1) is a first reference tilt value stored in advance in the memory of the optical disc apparatus, and Fo (I) is an optical disc. The second reference focus value stored in advance in the memory of the apparatus, Ti (2) is the second reference tilt value stored in advance in the memory of the optical disk apparatus, and Fo (P1) is when using the optical disk shown in FIG. Is the optimum focus control reference value when using the optical disc shown in FIG. 9, and Fo (P3) is the optimum focus control reference when using the optical disc shown in FIG. Value.

  Depending on the combination of the focus control value and the tilt control value, there are a combination that does not deviate the focus servo and a combination that deviates the focus servo. That is, there are combinations that allow focus control and combinations that make focus control difficult.

  FIG. 8 to FIG. 10 show such combinations. In the range from the region 404 to the region 406, the focus control is possible. In the region 404 to the region 406, the focus control is difficult. A plurality of elliptical areas in the areas 404 to 406 are contour lines indicating the focus servo enable status, and the optimum combination of the focus control reference value and the tilt control reference value for the optical disc is obtained as the distance from the center is increased.

  The optical disc apparatus stores a reference focus value, which serves as a reference for controlling the focus of the objective lens 2 with respect to the optical disc 50, in the memory 13. The recording quality is improved by changing the reference value of the focus control according to each optical disc 50 around the reference focus value. Since the position of the recording layer of the optical disc and the warp of the optical disc cannot be directly measured in actual use, a plurality of test data are recorded on the optical disc 50 to be used while changing the position of the objective lens 2 and the recorded test is performed. By reproducing the data and performing a certain check process, the condition for the best recording quality of the optical disk to be used is selected from the conditions used for recording the test data, and the position of the objective lens 2 is determined. .

  The test data is recorded in the second embodiment in the first reference focus value Fo (H) stored in the memory 13 and the first corrected focus value obtained by adding a predetermined value to the first reference focus value Fo (H). Fo (C) and a second corrected focus value Fo (D) obtained by subtracting a predetermined value from the first reference focus value Fo (H), and a focus value for recording test data from these three focus values The test data is recorded by a combination of the determined focus value and the first reference tilt value Ti (1). Further, the second reference focus value Fo (I) stored in the memory 13, the third corrected focus value Fo (E) obtained by adding a predetermined value to the second reference focus value Fo (I), and the second reference focus. A fourth modified focus value Fo (F) obtained by subtracting a predetermined value from the value Fo (I) is calculated, a focus value for recording test data is determined from these three focus values, and the determined focus value and the first focus value are calculated. Test data is recorded in combination with 2 reference tilt values Ti (2).

  Which one of the three focus values is selected depends on the state of the optical disk to be used, and will be described in the following order.

  First, there is a case where there is almost no displacement or warping of the recording layer in the optical disc 50 to be used. In this case, the relationship between the focus control value and the tilt control value that provides the best recording quality is, for example, a point P1 shown in FIG. The method for determining the focus value for recording the test data at this time is as follows.

  The first reference focus value Fo (H) stored in the memory 13 is set as a reference value for focus control, and the first reference tilt value Ti (1) stored in the memory 13 is set as a reference value for tilt control. Test data is recorded, the second reference focus value Fo (I) stored in the memory 13 is set as a reference value for focus control, and the second reference tilt value Ti (2) stored in the memory 13 is tilt controlled. Set to the reference value and record. At this time, for the optical disc having the characteristics shown in FIG. 8, the combination of the first reference focus value Fo (H) and the first reference tilt value Ti (1) shown at the point H, and the second reference shown at the point I. Test data is recorded by a combination of the focus value Fo (I) and the second reference tilt value Ti (2).

  In the case of FIG. 8, the focus error signal obtained by the combination of the first reference focus value Fo (H) and the first reference tilt value Ti (1) shown at the point H is substantially the same as that shown in FIG. Since the ratio between the positive-side amplitude amount and the negative-side amplitude amount of the focus error signal becomes equal, the focus value Fo (H) shown at the point H becomes substantially the same value as the focus value Fo (P1) shown at the point P1. It is determined that Further, the focus error signal obtained by the combination of the second reference focus value Fo (I) and the second reference tilt value Ti (2) shown at the point I is as shown in FIG. Since the ratio between the amplitude amount on the side and the amplitude amount on the negative side becomes equal, it is determined that the focus value Fo (I) indicated at the point I is substantially the same value as the focus value Fo (P1) indicated at the point P1. .

  In such a case, the test data is recorded with the first corrected focus value Fo (C) indicated by the point C, the test data is recorded with the second corrected focus value Fo (D) indicated by the point D, and the first data indicated by the point E is indicated. The first reference focus value Fo (H) indicated by the point H without recording the test data by the third corrected focus value Fo (E) and the test data by the fourth corrected focus value Fo (F) indicated by the point F. The optimal focus control value is calculated using only the second reference focus value Fo (I) indicated by the point I. Thereafter, the focus control reference value is determined from the result obtained by reproducing the test data recorded with the first reference focus value Fo (H) and the second reference focus value Fo (I).

  Next, there is a case where the optical disc 50 used has a recording layer misalignment or warpage. The relationship between the focus control value and the tilt control value that provides the best recording quality is, for example, the point P2 shown in FIG. 9 or the point P3 shown in FIG. The method for determining the focus value for recording the test data at this time is as follows.

  In the case of FIG. 9, the first reference focus value Fo (H) stored in the memory 13 is set as the reference value for focus control, and the first reference tilt value Ti (1) stored in the memory 13 is used as the reference for tilt control. The test data is recorded with the value set, and the second reference focus value Fo (I) stored in the memory 13 is set as the reference value for focus control, and the second reference tilt value Ti ( Set 2) as the reference value for tilt control and record. At this time, for the optical disc having the characteristics shown in FIG. 9, the combination of the first reference focus value Fo (H) and the first reference tilt value Ti (1) shown at the point H and the second reference shown at the point I. Test data is recorded by a combination of the focus value Fo (I) and the second reference tilt value Ti (2).

  In this case, the focus error signal obtained by the combination of the first reference focus value Fo (H) and the first reference tilt value Ti (1) indicated by the point H is as shown in FIG. Since the positive amplitude amount is larger than the negative amplitude amount, it is determined that the first reference focus value Fo (H) indicated at the point H is different from the focus value Fo (P2) indicated at the point P2. At the same time, when the test data is recorded by the combination of the second corrected focus value Fo (D) and the first reference tilt value Ti (1) indicated by the point D, the positive amplitude amount of the focus error signal is negative. It is determined that it will be larger than the amplitude amount. Further, the focus error signal obtained by the combination of the second reference focus value Fo (I) and the second reference tilt value Ti (2) shown at the point I is as shown in FIG. Since the amplitude amount on the side becomes larger than the amplitude amount on the negative side, it is determined that the second reference focus value Fo (I) indicated at the point I is different from the focus value Fo (P2) indicated at the point P2. At the same time, when the test data is recorded by the combination of the fourth corrected focus value Fo (F) and the second reference tilt value Ti (2) indicated by the point F, the positive amplitude amount of the focus error signal is negative. It is determined that it will be larger than the amplitude amount.

  In such a case, the test data is not recorded with the second corrected focus value Fo (D) indicated by the point D, and the subsequent processing is performed using the first corrected focus value Fo (C) indicated by the point C. The subsequent processing is performed using the third corrected focus value Fo (E) indicated by the point E without recording the test data using the fourth corrected focus value Fo (F) indicated by the point F. Thereafter, the focus control reference value is determined from the result obtained by reproducing the test data recorded with the first corrected focus value Fo (C) and the third corrected focus value Fo (E).

  In the case of FIG. 10, the first reference focus value Fo (H) stored in the memory 13 is set as the reference value for focus control, and the first reference tilt value Ti (1) stored in the memory 13 is used as the reference for tilt control. The test data is recorded, and the second reference focus value Fo (I) stored in the memory 13 is set as the reference value for focus control, and the second reference tilt value Ti stored in the memory 13 is set. Set (2) as the reference value for tilt control and record. At this time, for the optical disc having the characteristics shown in FIG. 10, the combination of the first reference focus value Fo (H) and the first reference tilt value Ti (1) indicated by the point H, and the second reference indicated by the point I. Test data is recorded by a combination of the focus value Fo (I) and the second reference tilt value Ti (2).

  In this case, the focus error signal obtained by the combination of the first reference focus value Fo (H) and the first reference tilt value Ti (1) shown at the point H is as shown in FIG. Since the positive-side amplitude amount is smaller than the negative-side amplitude amount, it is determined that the focus value Fo (H) indicated at the point H is different from the focus value Fo (P2) indicated at the point P2. At the same time, when the test data is recorded by the combination of the first corrected focus value Fo (C) and the first reference tilt value Ti (1) shown at the point C, the positive amplitude amount of the focus error signal is negative. It is determined that it is smaller than the amplitude amount. Further, the focus error signal obtained by the combination of the second reference focus value Fo (I) and the second reference tilt value Ti (2) shown at the point I is as shown in FIG. Since the amplitude amount on the side is smaller than the amplitude amount on the negative side, it is determined that the focus value Fo (I) indicated at the point I is different from the focus value Fo (P2) indicated at the point P2.

  In such a case, the test data is not recorded with the first corrected focus value Fo (C) indicated by the point C, and the subsequent processing is performed using the second corrected focus value Fo (D) indicated by the point D. The subsequent processing is performed using the fourth corrected focus value Fo (F) indicated by the point F without recording the test data using the third corrected focus value Fo (E) indicated by the point E. Thereafter, the focus control reference value is determined from the result obtained by reproducing the test data recorded with the second corrected focus value Fo (D) and the fourth corrected focus value Fo (F).

  FIG. 11 is a flowchart showing a focus control method according to Embodiment 2 of the present invention, and shows a flow of recording test data based on the first reference tilt value and the first reference focus value.

  When the optical disk 50 is loaded in the optical disk apparatus, the CPU 14 rotates the spindle motor 6 via the driver 15 and causes the light source 1 to emit light via the driver 16 and the laser controller 15 (S101). Next, the CPU 14 reads the first reference tilt value Ti (1) and the first reference focus value Fo (H) from the memory 13 (S102), and the first reference tilt value Ti (1) and the first reference focus value Fo. Test data is recorded based on (H) (S103). Thereafter, the CPU 14 reproduces the test data recorded based on the first reference tilt value Ti (1) and the first reference focus value Fo (H) (S104), and the focus error signal generation circuit 8 performs focus based on the reproduction signal. An error signal is generated (S105). The generated focus error signal is sent to the signal measurement circuit 11, and the signal measurement circuit 11 compares the positive-side amplitude amount and the negative-side amplitude amount with respect to the reference voltage of the focus error signal (S106).

  At this time, the ratio of the positive-side amplitude amount to the negative-side amplitude amount with respect to the reference voltage of the focus error signal is compared, and as shown in FIG. 3A, the positive-side amplitude amount and the negative-side amplitude amount are Are equal to each other (S107), it is determined that the first reference focus value Fo (H) used for recording the test data is appropriate for the mounted optical disc, and the individual status of the optical disc 50 to be used is determined. It is determined that sufficient information is obtained to calculate the control reference value for the corresponding focus control, and the combination of the first reference tilt value Ti (1) and the first reference focus value Fo (H) is stored in the memory 13. (S108).

  Also, the ratio of the positive and negative amplitudes to the reference voltage of the focus error signal is compared, and the ratio of the positive and negative amplitudes is not equal, and the positive amplitude Is larger than the negative amplitude amount (S109), a first corrected focus value Fo (C) obtained by adding a predetermined value to the first reference focus value Fo (H) is calculated (S110). In this case, the first reference focus value Fo (H) used for recording the test data is not appropriate for the optical disc 50 to be used, and the end of the distribution indicating the relationship between the focus value and the tilt value capable of focus control is shown. It is judged that it is located in the direction. At the same time, when the test data is recorded with the second corrected focus value Fo (D), it is determined that the positive amplitude amount of the focus error signal is larger than the negative amplitude amount. Then, the combination of the first reference tilt value Ti (1) and the first corrected focus value Fo (C) is stored in the memory 13 (S111).

  In addition, the ratio of the positive amplitude amount to the negative amplitude amount with respect to the reference voltage of the focus error signal is compared, and the ratio of the positive amplitude amount to the negative amplitude amount is not equal, and the positive amplitude amount. Is not larger than the negative amplitude amount and the positive amplitude amount is smaller than the negative amplitude amount (S112), the second corrected focus value obtained by subtracting a predetermined value from the first reference focus value Fo (H). Fo (D) is calculated (S113). In this case, the first reference focus value Fo (H) used for recording the test data is not appropriate for the optical disc 50 to be used, and the end of the distribution indicating the relationship between the focus value and the tilt value capable of focus control is shown. It is judged that it is located in the direction. At the same time, when the test data is recorded with the first corrected focus value Fo (H), it is determined that the positive amplitude amount of the focus error signal is smaller than the negative amplitude amount. Then, the combination of the first reference tilt value Ti (1) and the second corrected focus value Fo (D) is stored in the memory 13 (S114).

  FIG. 12 is a flowchart showing a focus control method according to Embodiment 2 of the present invention. After test data is recorded based on the first reference tilt value and the first reference focus value, the second reference tilt value and the second reference tilt value are recorded. The flow of recording test data based on a focus value is shown.

  The CPU 14 reads the second reference tilt value Ti (2) and the second reference focus value Fo (I) from the memory 13 (S115), and sets the second reference tilt value Ti (2) and the second reference focus value Fo (I). Based on this, test data is recorded (S116). Thereafter, the CPU 14 reproduces the test data recorded based on the second reference tilt value Ti (2) and the second reference focus value Fo (I) (S117), and the focus error signal generation circuit 8 performs focusing based on the reproduction signal. An error signal is generated (S118). The generated focus error signal is sent to the signal measurement circuit 11, and the signal measurement circuit 11 compares the positive-side amplitude amount and the negative-side amplitude amount with respect to the reference voltage of the focus error signal (S119).

  At this time, the ratio of the positive-side amplitude amount to the negative-side amplitude amount with respect to the reference voltage of the focus error signal is compared, and as shown in FIG. 3A, the positive-side amplitude amount and the negative-side amplitude amount are Are equal (S120), it is determined that the second reference focus value Fo (I) used for recording the test data is appropriate for the mounted optical disc 50, and the individual status of the optical disc 50 to be used is determined. It is determined that sufficient information for calculating the control reference value for the focus control according to is obtained, and the combination of the second reference tilt value Ti (2) and the second reference focus value Fo (D) is stored in the memory 13. Store (S121).

  In addition, the ratio of the positive amplitude amount to the negative amplitude amount with respect to the reference voltage of the focus error signal is compared, and the ratio of the positive amplitude amount to the negative amplitude amount is not equal, and the positive amplitude amount. Is larger than the negative amplitude amount (S122), a third corrected focus value Fo (E) obtained by adding a predetermined value to the second reference focus value Fo (I) is calculated (S123). In this case, the second reference focus value Fo (I) used for recording the test data is not appropriate for the optical disc 50 to be used, and the end of the distribution indicating the relationship between the focus value and the tilt value capable of focus control is shown. It is judged that it is located in the direction. At the same time, when the test data is recorded with the fourth corrected focus value Fo (F), it is determined that the positive amplitude amount of the focus error signal is larger than the negative amplitude amount. Then, the combination of the second reference tilt value Ti (2) and the third corrected focus value Fo (E) is stored in the memory 13 (S124).

  Also, the ratio of the positive and negative amplitudes to the reference voltage of the focus error signal is compared, and the ratio of the positive and negative amplitudes is not equal, and the positive amplitude Is not larger than the negative-side amplitude amount and the positive-side amplitude amount is smaller than the negative-side amplitude amount (S125), a fourth corrected focus value obtained by subtracting a predetermined value from the second reference focus value Fo (I) Fo (F) is calculated (S126). In this case, the second reference focus value Fo (I) used for recording the test data is not appropriate for the optical disc 50 to be used, and the end of the distribution indicating the relationship between the focus value and the tilt value capable of focus control is shown. It is judged that it is located in the direction. At the same time, when the test data is recorded with the third corrected focus value Fo (E), it is determined that the positive amplitude amount of the focus error signal is further smaller than the negative amplitude amount. Then, the combination of the second reference tilt value Ti (2) and the fourth corrected focus value Fo (F) is stored in the memory 13 (S127).

  FIG. 13 is a flowchart showing a focus control method according to Embodiment 2 of the present invention, in which test data is recorded based on the first reference tilt value and the first reference focus value, and the second reference tilt value and the second reference focus are recorded. The flow of recording test data based on values and then determining the recording of subsequent test data based on the test results is shown.

  The CPU 14 stores the two combinations stored in the memory 13, that is, the first reference tilt value Ti (1) and the first reference focus value Fo (H), the first reference tilt value Ti (1) and the first corrected focus value Fo ( C), and any one of the first reference tilt value Ti (1) and the second corrected focus value Fo (D), the second reference tilt value Ti (2), the second reference focus value Fo (I), and the second reference The tilt value Ti (2) and the third corrected focus value Fo (E), and the second reference tilt value Ti (2) and the fourth corrected focus value Fo (F) are read (S128).

  At this time, when the first reference focus value Fo (H) is included in one of the two combinations read out (S129), the second reference is included in the other combination. It is sequentially confirmed whether any of the focus value Fo (I), the third correction focus value Fo (E), or the fourth correction focus value Fo (F) is included (S130 to S132). When the second reference focus value Fo (I) is included in another combination, the first reference focus value Fo (H) and the second reference focus value Fo (I) that have already recorded the test data are used. The subsequent test data is not recorded using the result obtained (S133). If the third correction focus value Fo (E) is included in the other combination, test data is recorded using the third correction focus value Fo (E) (S134). When the fourth correction focus value Fo (F) is included in the other combination, test data is recorded using the fourth correction focus value Fo (F) (S135). If any of the second reference focus value Fo (I), the third correction focus value Fo (E), and the fourth correction focus value Fo (F) is not included in the other combination, the optimum focus control reference value The process of calculating is canceled (S150).

  In addition, when the first correction focus value Fo (C) is included in one of the two combinations read out (S136), the second reference focus is included in the other combination. It is sequentially confirmed whether any of the value Fo (I), the third correction focus value Fo (E), or the fourth correction focus value Fo (F) is included (S137 to S139). When the second reference focus value Fo (I) is included in the other combination, the first corrected focus is obtained using the result using the second reference focus value Fo (I) in which the test data has already been recorded. Test data is recorded using only the value Fo (C) (S140). When the third correction focus value Fo (E) is included in the other combination, the test data is recorded using the first correction focus value Fo (C) and the third correction focus value Fo (E). This is performed (S141). When the fourth correction focus value Fo (F) is included in the other combination, the test data is recorded using the first correction focus value Fo (C) and the fourth correction focus value Fo (F). It performs (S142). If the second reference focus value Fo (I), the third corrected focus value Fo (E), and the fourth corrected focus value Fo (F) are not included in the other combination, the optimum focus control reference value The process of calculating is canceled (S151).

  In addition, when the second corrected focus value Fo (D) is included in one of the two combinations read out (S143), the second reference focus is included in the other combination. It is sequentially confirmed whether any of the value Fo (I), the third correction focus value Fo (E), or the fourth correction focus value Fo (F) is included (S144 to S146). When the second reference focus value Fo (I) is included in another combination, the second corrected focus value Fo is obtained using the result of the second reference focus value Fo (I) already recorded by test. Test data is recorded using (D) (S147). When the third correction focus value Fo (E) is included in the other combination, the test data is recorded using the second correction focus value Fo (D) and the third correction focus value Fo (E). It performs (S148). When the fourth correction focus value Fo (F) is included in the other combination, the test data is recorded using the first correction focus value Fo (C) and the fourth correction focus value Fo (F). Perform (S149). If the second reference focus value Fo (I), the third corrected focus value Fo (E), and the fourth corrected focus value Fo (F) are not included in the other combination, the optimum focus control reference value The process of calculating is canceled (S152).

  As described above, in the process of calculating the optimum focus control reference value of the optical disc by recording a plurality of test data, the first reference focus value Fo (H) and the first reference tilt value Ti (1) are calculated. Since the test data recording based on the second reference focus value Fo (I) and the second reference tilt value Ti (2) is not performed after the test data recording based on the second reference focus value Fo (I) and the second reference tilt value Ti (2), the test data cannot be reproduced. The calculated optimum focus control value cannot be obtained with sufficient accuracy even though the process of calculating the optimum focus control value is performed due to a lack of information obtained by reproducing the test record. It is possible to prevent the information itself from being unexpectedly lost and the process of calculating the optimum focus control value from being interrupted. As a result, an optical disc apparatus capable of calculating the optimum position of the objective lens for the optical disc to be used in consideration of the deviation and warpage even when using an optical disc with a large positional deviation and warpage of the recording layer, and its Focus control can be realized.

1 is a block diagram of an optical disc apparatus according to Embodiment 1 of the present invention. The figure which shows the focus error signal generation circuit in Embodiment 1 of this invention The figure which shows the focus error signal produced | generated when reproducing | regenerating the test data in Embodiment 1 of this invention The figure which shows the method of selecting the focus control reference value in Embodiment 1 of this invention. The figure which shows the method of selecting the focus control reference value in Embodiment 1 of this invention. The figure which shows the method of selecting the focus control reference value in Embodiment 1 of this invention. A flowchart showing a focus control method in Embodiment 1 of the present invention. The figure which shows the method of selecting the focus control reference value in Embodiment 2 of this invention. The figure which shows the method of selecting the focus control reference value in Embodiment 2 of this invention. The figure which shows the method of selecting the focus control reference value in Embodiment 2 of this invention. The flowchart which shows the focus control method in Embodiment 2 of this invention. The flowchart which shows the focus control method in Embodiment 2 of this invention. The flowchart which shows the focus control method in Embodiment 2 of this invention. The figure which shows the range of the combination of the focus control value and tilt control value in which focus control is possible The figure which shows the range of the combination of the focus control value and tilt control value in which focus control is possible The figure which shows the range of the combination of the focus control value and tilt control value in which focus control is possible

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Light source 2 Objective lens 3 Lens holder 4 Actuator 4a Focus adjustment coil 5 Quadrant light detector 5a Photo detector 5b Photo detector 6 Spindle motor 7 Feed motor 8 Focus error signal generation circuit 8a Balance circuit 8b Differential circuit 9 RF Signal detection circuit 10 Focus servo circuit 11 Signal measurement circuit 12 Jitter detection circuit 13 Memory 14 CPU
DESCRIPTION OF SYMBOLS 15 Laser control part 16 Driver 50 Optical disk 100 Optical head part 200 Pickup module

Claims (16)

Focus error signal generating means for generating a focus error signal based on reflected light from the optical disc;
Servo processing means for performing focus control;
Storage means for storing a reference focus value serving as a reference for the focus control;
Control means for generating a first correction focus value obtained by adding a predetermined value to the reference focus value and a second correction focus value obtained by subtracting the predetermined value from the reference focus value;
The control means records test data based on the reference focus value, and a ratio between a positive amplitude amount and a negative amplitude amount with respect to a reference voltage of a focus error signal generated when the test data is reproduced. And determining whether to record the test data using one of the reference focus value, the first corrected focus value, and the second corrected focus value. The control means records the test data based on the reference focus value, and calculates a positive amplitude amount and a negative amplitude amount with respect to a reference voltage of a focus error signal generated when reproducing the test data. 2. The optical disc apparatus according to claim 1, wherein when the ratio is equal, the test data is recorded using only the reference focus value without using the first correction focus value and the second correction focus value. The control means determines that the ratio between the positive amplitude amount and the negative amplitude amount is equal when the difference between the positive amplitude amount and the negative amplitude amount is less than a predetermined amount. The optical disc apparatus according to claim 2. The control means records the test data based on the reference focus value, and a positive amplitude amount with respect to a reference voltage of a focus error signal generated when reproducing the test data is larger than a negative amplitude amount. 2. The optical disc apparatus according to claim 1, wherein the test data is recorded using the first corrected focus value instead of the reference focus value. The control means determines that the positive amplitude amount is greater than the negative amplitude amount when a difference between the positive amplitude amount and the negative amplitude amount is a predetermined amount or more. The optical disc device according to claim 4. The control means records the test data based on the reference focus value, and a positive amplitude amount with respect to a reference voltage of a focus error signal generated when reproducing the test data is smaller than a negative amplitude amount. 2. The optical disc apparatus according to claim 1, wherein the test data is recorded using the second corrected focus value instead of the reference focus value. The control means determines that the positive amplitude amount is smaller than the negative amplitude amount when a difference between the positive amplitude amount and the negative amplitude amount is a predetermined amount or more. The optical disc apparatus according to claim 6. Focus error signal generating means for generating a focus error signal based on reflected light from the optical disc;
Servo processing means for performing focus control and tilt control;
Storage means for storing a first reference focus value and a second reference focus value serving as a reference for the focus control, and a first reference tilt value and a second reference tilt value serving as a reference for tilt control;
A first correction focus value obtained by adding a predetermined value to the first reference focus value and a second correction focus value obtained by subtracting the predetermined value from the first reference focus value are generated, and the predetermined value is set as the second reference focus value. Control means for generating a fourth corrected focus value obtained by subtracting the predetermined value from the added third corrected focus value and the second reference focus value;
The control means records the test data based on the combination of the first reference focus value and the first reference tilt value, and corrects the reference voltage of the focus error signal generated when reproducing the test data with respect to the reference voltage. Recording of the test data using any one of the first reference focus value, the first correction focus value, and the second correction focus value based on the ratio of the amplitude amount on the side and the amplitude amount on the negative side. A reference voltage of a focus error signal generated when recording the test data based on a combination of the second reference focus value and the second reference tilt value and reproducing the test data. The second reference focus value, the third corrected focus value, and the fourth based on the ratio of the positive-side amplitude amount and the negative-side amplitude amount to Optical disc apparatus characterized by determining whether to record the test data using any of the positive focus values. Stores the reference focus value, which is the reference for focus control,
A focus control method for generating a first correction focus value obtained by adding a predetermined value to the reference focus value and a second correction focus value obtained by subtracting the predetermined value from the reference focus value,
Test data is recorded based on the reference focus value, and based on the ratio of the positive amplitude amount and the negative amplitude amount to the reference voltage of the focus error signal generated when reproducing the test data, A focus control method for an optical disc apparatus, comprising: determining whether to record the test data using any one of a reference focus value, the first corrected focus value, and the second corrected focus value. When the test data is recorded based on the reference focus value, and the ratio of the positive amplitude amount and the negative amplitude amount to the reference voltage of the focus error signal generated when reproducing the test data is equal, 10. The focus control method for an optical disc apparatus according to claim 9, wherein the test data is recorded using only the reference focus value without using the first correction focus value and the second correction focus value. The ratio between the positive amplitude amount and the negative amplitude amount is determined to be equal when a difference between the positive amplitude amount and the negative amplitude amount is less than a predetermined amount. Item 11. A focus control method for an optical disc apparatus according to Item 10. When the test data is recorded based on the reference focus value and the positive amplitude amount with respect to the reference voltage of the focus error signal generated when reproducing the test data is larger than the negative amplitude amount, the reference focus 10. The focus control method for an optical disc apparatus according to claim 9, wherein the test data is recorded using the first corrected focus value instead of the value. 13. The positive amplitude amount is determined to be larger than the negative amplitude amount when a difference between the positive amplitude amount and the negative amplitude amount is a predetermined amount or more. Control method for optical disc apparatus of the present invention. When the test data is recorded based on the reference focus value and the positive amplitude amount with respect to the reference voltage of the focus error signal generated when the test data is reproduced is smaller than the negative amplitude amount, the reference focus 10. The focus control method for an optical disc apparatus according to claim 9, wherein the test data is recorded using the second corrected focus value instead of the value. 15. The method according to claim 14, wherein when the difference between the positive amplitude amount and the negative amplitude amount is equal to or greater than a predetermined amount, the positive amplitude amount is determined to be smaller than the negative amplitude amount. Control method for optical disc apparatus of the present invention. Storing a first reference focus value and a second reference focus value serving as a reference for focus control, and a first reference tilt value and a second reference tilt value serving as a reference for tilt control;
A first correction focus value obtained by adding a predetermined value to the first reference focus value and a second correction focus value obtained by subtracting the predetermined value from the first reference focus value are generated, and the predetermined value is set as the second reference focus value. A focus control method for generating a fourth corrected focus value obtained by subtracting the predetermined value from the added third corrected focus value and the second reference focus value,
The test data is recorded based on a combination of the first reference focus value and the first reference tilt value, and a positive amplitude amount with respect to a reference voltage of a focus error signal generated when reproducing the test data; Based on the ratio to the negative amplitude amount, it is determined whether to record the test data using any one of the first reference focus value, the first correction focus value, and the second correction focus value. In addition, the test data is recorded based on the combination of the second reference focus value and the second reference tilt value, and the positive amplitude with respect to the reference voltage of the focus error signal generated when the test data is reproduced The second reference focus value, the third correction focus value, and the fourth correction focus value based on the ratio of the amount and the negative amplitude amount. Of focus control method of the optical disk apparatus characterized by determining whether to record the test data with either.

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