JP2008059703A - Optical disc recording / reproducing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical disc recording / reproducing apparatus capable of improving recording and reproducing performance by indirectly measuring variation in thickness of an optical disc and changing a focus offset according to the measured value.
A ratio obtained by dividing a focus error signal by a full addition signal is calculated, an optical disc thickness variation is indirectly measured, and the value is compared with a preset first threshold value, which exceeds an allowable range. In such a case, by selecting an appropriate value from the focus offset adjustment value table set by learning in advance and adjusting the focus offset, the jitter of the reproduction waveform is reduced, and the recording and reproduction performance can be improved.
[Selection] Figure 1

Description

  The present invention relates to an optical disc recording / reproducing apparatus that handles CD, DVD, HD DVD, or the like.

  A plurality of types of recording density optical disks called CD (Compact Disc) standards and DVD (Digital Versatile Disk) standards are already widely used. In recent years, by recording information using laser light of a blue-violet wavelength, In addition, an ultra-high density optical disk HD DVD (High Density Digital Versatile Disk) with a higher recording density has been put into practical use.

  In order to improve the recording density, the track pitch and pit pitch of the optical disc are reduced, the aperture ratio of the objective lens is increased, and the wavelength of the laser light is shortened, so that the thickness of the substrate protective layer of the optical disc (from the outer surface of the optical disc to the recording layer) Variation of the distance up to the distance (hereinafter referred to as the thickness of the substrate) has increased the influence on the accuracy and stability of recording and reproduction. Also, it is known that the same problem occurs when the thickness of the substrate varies even when the wavelength of the laser beam varies.

  In order to improve accuracy and stability in recording and reproducing information on the optical disk, a part of the optical disk recording / reproducing apparatus detects spherical aberration due to variations in the thickness of the optical disk substrate as a thickness error signal using a hologram element. Then, a configuration for adjusting the tracking offset is considered (for example, see Patent Document 1).

  On the other hand, in addition to the variation in the thickness of the optical disk substrate, a substrate having a unique thickness outside the standard of CD and DVD has appeared on the market. As a prominent example in which the thickness of the substrate of the optical disc is different from the standard of CD or DVD, one surface called Dual Disc (dual disc) is an information recording surface conforming to the DVD standard, and the other surface is a “non-DVD surface”. Alternatively, there is an optical disc composed of a pseudo CD information recording surface that does not conform to the CD standard called “music-only surface”. The thickness of the substrate on the information recording surface side which is not compliant with the CD standard called “non-DVD surface” or “music-only surface” is about 0.9 mm, which is thinner than 1.2 mm which is the CD standard. Therefore, there is a possibility that the optical disk recording / reproducing apparatus set to the reproducing level conforming to the CD standard cannot be reproduced.

  FIG. 6 schematically shows the spot shape on the photodetector in which the laser light irradiated to the CD standard optical disk is reflected by the information recording surface, and the reflected light is collected and received by the astigmatism method. FIG. The photodetector 50 includes light receiving units 50a to 50d divided into four. 6A shows a case where the focal position of the laser beam is slightly shifted from the information recording surface to the substrate surface side (defocus position), and FIG. 6B shows that the focal position is located on the information recording surface. In this case, FIG. 6C shows a case where the in-focus position is slightly shifted from the information recording surface to the side opposite to the substrate surface (defocus position).

  FIG. 7 shows that the laser light applied to the information recording surface that does not conform to the CD standard called “non-DVD surface” or “music-only surface” of the dual disc described above is reflected by the information recording surface, and the reflected light thereof. FIG. 7 is a diagram schematically showing the spot shape on the photodetector that is focused and received so that the difference from FIG. 6 becomes clear. FIGS. 7A, 7B, and 7C show the same positional relationship as FIGS. 6A, 6B, and 6C. In the case of the dual disk, aberration is generated, and therefore, it can be seen that the change in the spot shape at the defocus position before and after the information recording surface is small as compared with the CD standard optical disk.

FIG. 8 shows the relationship between the magnitude of the focus error signal and the defocus amount. When the output signals of the light receiving units 50a to 50d are A, B, C, and D, respectively, the focus error signal FE is expressed by FE = (A + C) − (B + D). FIG. 8A shows the case of FIG. 5 (CD standard optical disc), and FIG. 8B shows the case of FIG. 7 (dual disc). Compared to FIG. 8A, in FIG. 8B, the focus error signal becomes half or less. This is because the change in the spot shape at the defocus position before and after the information recording surface is small in the case of the dual disc as described above, as compared with the CD standard optical disc. In such a state, the jitter of the data reproduction signal (RF signal) waveform becomes large, and there is a possibility that it cannot be reproduced accurately.
JP 2001-273648 A

  In order to correct spherical aberration due to variations in the thickness of the substrate of the optical disk, a spherical element is used in the optical pickup or a relay lens is used to measure the magnitude of the spherical aberration and correct it using the measured value. Although a method has been adopted, components for measuring spherical aberration have been an obstacle to miniaturization and cost reduction of optical pickups.

  Detector for detecting aberrations in order to prevent deterioration in recording and reproduction performance caused by aberrations caused by variations in the thickness of the optical disk substrate or a thickness different from the standard of CD or DVD Therefore, there has been a demand for an optical disc recording / reproducing apparatus that does not require a simple structure and prevents performance degradation.

  The present invention has been made to solve the above problems, and by indirectly measuring the variation in the thickness of the optical disk, the focus offset or the focus balance or the RF equalizer is changed according to the measured value. An object of the present invention is to provide an optical disc recording / reproducing machine capable of improving recording and reproducing performance.

  In order to achieve the above object, an optical disc recording / reproducing apparatus of the present invention includes an objective lens for condensing laser light on an information recording surface of an optical disc and a divided light receiving portion for receiving reflected light from the optical disc. An optical pickup having a photodetector, focus error signal generating means for generating a focus error signal from the output signal of the photodetector, and a full addition signal for generating a full addition signal from the output signal of the photodetector Generating means; ratio calculating means for calculating a ratio between the focus error signal and the full addition signal; and comparing means for comparing the ratio obtained by the ratio calculating means with a preset first threshold value. The amount of deviation between the focus point of the objective lens and the focus point due to the focus error signal is compensated according to the value calculated by the comparison means. And having a focus offset adjustment means for setting the focus offset adjustment value.

  An optical disk recording / reproducing apparatus of the present invention includes an objective lens for condensing a laser beam on an information recording surface of an optical disk, and a photodetector including a divided light receiving unit that receives reflected light from the optical disk; An optical pickup, a focus error signal generating means for generating a focus error signal from the output signal of the photodetector, a full addition signal generating means for generating a full addition signal from the output signal of the photodetector, and the light Reproduction signal generation means for generating a reproduction signal from the output signal of the detector, ratio calculation means for calculating the ratio of the focus error signal and the full addition signal, and the ratio obtained by the ratio calculation means are preset. Comparing means for comparing with the first threshold value, and adjusting the amplitude of the high frequency component of the reproduction signal in accordance with the value calculated by the comparing means And having an RF equalizer adjustment means for setting the RF equalizer adjustment value.

  According to the present invention, it is possible to improve the performance of recording and reproducing information on an optical disc.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a block diagram showing the configuration of an optical disc recording / reproducing apparatus 1 to which the present invention is applied. The optical disk 2 is an optical disk capable of recording user data or a read-only optical disk. Land tracks and group tracks are formed in a spiral shape on the surface of the optical disc 2, and the optical disc 2 is driven to rotate by a disc motor 3. The disk motor 3 is controlled by a disk motor control circuit 4.

  Information recording and reproduction with respect to the optical disc 2 are performed by the optical pickup 5. The optical pickup 5 is connected to the thread motor 6 via a connecting portion 8 including a gear and the like. The thread motor 6 is controlled by a thread motor control circuit 9.

  A speed detector 7 is connected to the thread motor control circuit 9, and a speed signal of the optical pickup 5 detected by the speed detector 7 is sent to the thread motor control circuit 9. The sled motor 6 is controlled by a sled motor control circuit 9, and the optical pickup 5 is moved in the radial direction of the optical disc 2 by the driving force generated by the sled motor 6.

  The optical pickup 5 is provided with an objective lens 10 movably supported by a wire or a leaf spring (not shown). The objective lens 10 can be moved in the focusing direction (the optical axis direction of the lens) by driving the focus direction driving coil 11, and the tracking direction (the direction orthogonal to the optical axis of the lens) by driving the track direction driving coil 12. ) Is possible.

  The modulation circuit 13 performs 8-14 modulation (EFM) on the data supplied from the host device 37 via the interface circuit 36 at the time of recording information, and provides the modulated data to the laser control circuit 14. The laser control circuit 14 supplies a write signal to the semiconductor laser diode 15 based on the EFM data supplied from the modulation circuit 13 during information recording (mark formation).

  The semiconductor laser diode 15 generates laser light in accordance with a signal supplied from the laser control circuit 14. Laser light 16 emitted from the semiconductor laser diode 15 is irradiated onto the optical disc 2 through the collimating lens 17, the half prism 18, and the objective lens 10. The reflected light 19 from the optical disk 2 is guided to the photodetector 22 through the objective lens 10, the half prism 18, the condenser lens 20, and the cylindrical lens 21.

  The photodetector 22 is composed of four-divided light receiving portions 22a to 22d, and these output signals are differential amplifiers (OP1) 25 via current / voltage conversion amplifiers 23a to 23d and adders 24a to 24d. , Are supplied to the differential amplifier (OP2) 27.

  The differential amplifier (OP1) 25 outputs a focus error signal (FE) corresponding to the difference between both output signals of the adders 24a and 24b. This output is supplied to the focussing control circuit 26. The output signal of the focussing control circuit 26 is supplied to the focus direction drive coil 11. As a result, the objective lens 10 is controlled so that the laser beam 16 is always just focused on the information recording surface of the optical disc 2.

  The differential amplifier (OP2) 27 outputs a tracking error signal (TE) corresponding to the difference between both output signals of the adders 24c and 24d. This output is supplied to the tracking control circuit 28. The output signal of the tracking control circuit 28 is supplied to the track direction drive coil 12. A tracking error signal used in the tracking control circuit 28 is supplied to the sled motor control circuit 9.

  When the objective lens 10 is controlled by the tracking control circuit 28, the thread motor 6, that is, the optical disk 2 of the optical pickup 5 is positioned so that the objective lens 10 is positioned near the center position in the optical pickup 5 by the thread motor control circuit 9. Radial movement is controlled.

  A sum signal of the output signals of the light receiving portions 22a to 22d of the photodetector 22, that is, an adder 24e that adds both output signals of the adders 24c and 24d constitutes a reproduction signal generating means, and this added reproduction signal (RF ) Reflects the change in reflectance from the pits (recording data) recorded on the optical disc 2. The reproduction signal (RF) is supplied to the data reproduction circuit 29.

  The data reproduction circuit 29 reproduces recorded data based on the reproduction clock signal from the PLL circuit 30. The data reproduction circuit 29 has a function of measuring the amplitude of the reproduction signal (RF), and the measured value is read by the CPU 32.

  The reproduction data reproduced by the data reproduction circuit 29 is output to the host device 37 via the interface circuit 36 after the error correction circuit 35 performs error correction using the assigned error correction code.

  The addition amplifier (OP3) 38 generates a full addition signal that is a sum signal of the output signals of the adders 24c and 24d. The output of the addition amplifier (OP3) 38 is transmitted to the CPU 32 through the bus 31.

  The disk motor control circuit 4, thread motor control circuit 9, modulation circuit 13, laser control circuit 14, PLL circuit 30, data reproduction circuit 29, focussing control circuit 26, tracking control circuit 28, etc. are one servo control circuit. These circuits can be configured in the LSI chip, and these circuits are controlled by the CPU 32 via the bus 31. The CPU 32 comprehensively controls the optical disc recording / reproducing apparatus 1 in accordance with an operation command supplied from the host device 37 via the interface circuit 36. The CPU 32 uses the RAM 33 as a work area and performs predetermined control according to a program including the present invention recorded in the ROM 34.

  The CPU 32 monitors the output signal from the focusing control circuit 26 through the bus 31, receives the focus error signal output from the differential amplifier (OP1) 25, and stores it in the RAM 33 as the amplitude value FEpp of the focus error signal. The CPU 32 receives the full addition signal from the addition amplifier (OP3) 38 through the bus 31, and stores it in the RAM 33 as the amplitude value ADpp of the full addition signal.

  The CPU 32 has a function as ratio calculation means for calculating a ratio from the values of FEpp and ADpp stored in the RAM 33. The ratio FEnm is a value obtained by dividing FEpp by ADpp, and the calculated FEnm is stored in the RAM 33.

  Further, the CPU 32 has a function of comparison means for comparing the predetermined first threshold value R1 in the program stored in the ROM 34 with the above-described FEnm, and calculates the size determination and the difference between them. Further, the CPU 32 compares the predetermined second threshold value R2 in the program stored in the ROM 34 with the above-mentioned FEnm, and calculates the magnitude and the difference. The first threshold value R1 and the second threshold value R2 stored in the ROM 34 will be described later.

  Further, the CPU 32 refers to the focus point of the objective lens 10 while referring to the focus offset adjustment value or the focus balance adjustment value stored in the ROM 34 based on the magnitude and difference between the first threshold value R1 and FEnm calculated by the comparison means. A focus offset adjustment value or a focus balance adjustment value for correcting a deviation amount from the focus point due to the focus error signal is set. Further, the CPU 32 sets an RF equalizer adjustment value for adjusting the amplitude of the high frequency component of the reproduction signal while referring to the RF equalizer adjustment value stored in the ROM 34, and the RF reproduction signal 2 is input into the data reproduction circuit 29. An RF equalizer circuit (not shown) provided in the previous stage to be digitized is controlled. The jitter after binarization of the reproduction signal is reduced by adjusting the amplitude of the high frequency component.

  FIG. 2 is a flowchart for adjusting the focus offset or the focus balance by indirectly measuring the variation in the thickness of the optical disc. First, in S1, the presence or absence of the optical disc 2 is recognized.

  In S <b> 2, a lens down operation is performed in which the objective lens 10 is once moved away from the surface of the optical disk 2. In S3, the laser beam is emitted and the laser beam 16 is irradiated toward the optical disc 2. In S4, a lens-up operation is performed in which the objective lens 10 is gradually brought closer to the surface of the optical disc 2.

  In S5, the CPU 32 receives the focus error signal from the differential amplifier (OP1) 25 via the focusing control circuit 26 and the bus 31, and measures the amplitude of the focus error signal. Thereafter, the CPU 32 stores the measured amplitude value FEpp of the focus error signal in the RAM 33.

  In S6, the CPU 3 receives the full addition signal from the addition amplifier (OP3) 38 via the bus 31 and measures the amplitude of the full addition signal. Thereafter, the CPU 32 stores the measured amplitude value ADpp of the full addition signal in the RAM 33.

  In S7, the CPU 32 obtains the ratio FEnm by dividing the value of FEpp stored in the RAM 33 by the value of ADpp. The calculated FEnm is stored in the RAM 33. The ratio FEnm is a value obtained by dividing the focus error signal by the full addition signal.

  As shown in FIG. 7, in the case of an optical disc having a substrate thickness different from the standard, such as a dual disc, the focus error signal may be less than half the level of the focus error signal. is there. In addition, the magnitude of the focus error signal varies as the thickness of the substrate varies. However, even if the thickness of the substrate does not vary, for example, the level of the focus error signal may be halved even if the amount of light (the amount of laser light reaching the photodetector) is reduced. There are various reasons for the decrease in the amount of light, such as a decrease in the amount of emitted laser light, a decrease in the reflectance of the information recording surface of the optical disc, and a contamination on the surface of the optical disc.

  If the level of the focus error signal is reduced, it cannot be determined whether it is due to variations in the thickness of the board or the decrease in the amount of light, but by dividing the focus error signal by the full addition signal, the cause of fluctuations in the amount of light Can be removed. This is because the level of the total addition signal is hardly affected by variations in the thickness of the substrate, but is almost directly affected by variations in the amount of light. Therefore, a change in the ratio FEnm, which is a value obtained by dividing the focus error signal by the full addition signal, indirectly represents a variation in the thickness of the optical disc.

  In S8, the CPU 32 compares the predetermined first threshold value R1 and second threshold value R2 stored in the ROM 34 with the above-described FEnm, and calculates the difference. When the value of FEnm is smaller than the first threshold value R1, the first threshold value R1 is a threshold value indicating that the substrate thickness variation exceeds a certain range. The second threshold value R2 is a threshold value indicating that when the value of FEnm is larger than the second threshold value R2, the substrate thickness variation exceeds a certain range. The value of FEnm is arbitrarily set according to the gains of the differential amplifier (OP1) 25, the focusing control circuit 26 and the addition amplifier (OP3) 38 that generate the amplitude values of FEpp and ADpp which are the basis of the value of FEnm. Therefore, the first threshold value R1 and the second threshold value R2 are determined by the gain.

  As an example, when setting using a standard disc that conforms to the CD standard, the overall gain of the differential amplifier (OP1) 25 and the focusing control circuit 26 is set so that FEpp is about 2 V, and ADpp is set. Assuming that the gain of the addition amplifier (OP3) 38 is set so that is about 0.5V, FEnm is 2V / 0.5V = 4. In the state set in this way, FEnm is 1 V / 0.5 V = 2 assuming that an optical disc having a thickness less than the standard is loaded and the amplitude of the focus error signal is halved. For example, if the threshold value R1 is set to 2.5, R1> FEnm and FEnm−R1 = −0.5. In this case, the process proceeds to a step of changing the focus offset or the focus balance.

  In S8, if R1 <FEpp <R2, it is determined that the variation in substrate thickness is within an allowable range, and the process proceeds to S9. If not, the difference between FEpp and the first threshold R1 or the second threshold R2 is determined. Calculate and move to S11. In S9, adjustment is performed within the range of automatic adjustment without changing the focus offset. Next, the process proceeds to S10 to perform a normal operation.

  In S11, the CPU 32 sets and adjusts the focus offset adjustment value. The focus offset adjustment value or the focus balance adjustment value is selected from a focus offset adjustment value table 40 stored in advance in the ROM 34 or a focus balance adjustment value table (not shown). An adjustment value is selected from the table based on the difference between FEnm calculated in S8 and the first threshold value R1 or the second threshold value R2. The selected adjustment value is transmitted to the focusing control circuit 26, and the objective lens is controlled in accordance with the level of variation in substrate thickness. Thereafter, the process proceeds to S10 and a normal operation is performed.

  The ROM 34 has a function as a focus offset adjustment value storage unit that stores a plurality of predetermined focus offset adjustment values or focus balance adjustment values. The optical disc recording / reproducing apparatus 1 performs recording / reproduction of various specific evaluation optical discs by pre-learning for setting a focus offset adjustment value performed at a stage before the user records and reproduces data after the manufacturing process or shipment. The focus offset adjustment value corresponding to the thickness of the substrate and the reflectance variation of the information recording surface, and the difference between the corresponding FEnm and the first threshold value R1 or the second threshold value R2 is the focus offset adjustment value of the ROM 34. It is stored in the table 40 or the focus balance adjustment value table.

  FIG. 3 is a diagram illustrating an example of the focus offset adjustment value table 40. FEnm is smaller than the first threshold value R1 (FEnm <R1), and the focus offset adjustment value is set according to the magnitude of the difference (FEnm−R1). In FIG. 3, the focus offset adjustment value when the difference is Df1 is Fo1, and the focus offset adjustment value when Dfn is Fon. In this case, there are n-stage adjustment values. However, if fine adjustment is not required, the adjustment value is two-stage adjustment. Further, if FEnm <R1, the focus offset adjustment value can be used regardless of the difference. Can be fixed to one set value in some cases.

  As described above, the ratio FEnm, which is a value obtained by dividing the focus error signal by the total addition signal, is calculated, the thickness variation of the optical disc 2 is indirectly measured, and the value and the preset first threshold value R1 or the first threshold value. Compared with the threshold value R2 of 2, the jitter of the reproduced waveform is reduced by selecting an appropriate value from the focus offset adjustment value table 40 set by learning in advance and adjusting the focus offset when the allowable range is exceeded. Recording and reproduction performance can be improved.

  FIG. 4 is a flowchart for adjusting the RF equalizer by indirectly measuring the thickness variation of the optical disc. In each part of the second embodiment, the same parts as those in the first embodiment shown in FIG. The second embodiment is different from the first embodiment in that the focus offset or focus balance adjustment value setting in S11 in FIG. 2 is replaced with the RF equalizer adjustment value setting in S12 in FIG. Since S1 to S8 are the same as those in the first embodiment, the description thereof is omitted.

  In S12, the CPU 32 sets and adjusts the adjustment value of the RF equalizer. The adjustment value of the RF equalizer is selected from the RF equalizer adjustment value table 41 stored in the ROM 34 in advance. An adjustment value is selected from the table based on the difference between FEnm calculated in S8 and the first threshold value R1 or the second threshold value R2. The selected adjustment value is transmitted to the data reproduction circuit 29, and when the RF signal is binarized by boosting and adjusting the amplitude of the RF high-frequency component in accordance with the level of variation in substrate thickness. Improve the jitter. Thereafter, the process proceeds to S10 and a normal operation is performed.

  The ROM 34 has a function as an RF equalizer adjustment value storage unit that stores a plurality of predetermined RF equalizer adjustment values. The optical disc recording / reproducing apparatus 1 performs recording / reproduction of various specific evaluation optical discs by pre-learning for setting an RF equalizer adjustment value performed at a stage before the user records and reproduces data after the manufacturing process or shipment. The RF equalizer adjustment value corresponding to the thickness of the substrate and the reflectance variation of the information recording surface, and the difference between the corresponding FEnm and the first threshold value R1 or the second threshold value R2, is the RF equalizer adjustment value of the ROM 34. Store in table 41.

  FIG. 5 is a diagram showing an example of the RF equalizer adjustment value table 41. FEnm is smaller than the first threshold value R1 (FEnm <R1), and the RF equalizer adjustment value is set according to the magnitude of the difference (FEnm−R1). FIG. 5 shows that the RF equalizer adjustment value is Eq1 when the difference is Df1, and the RF equalizer adjustment value is Eqn when the difference is Dfn. In this case, there are n-stage adjustment values. However, if fine adjustment is not necessary, the adjustment value is two-stage adjustment, or further simplified, and when FEnm <R1, the RF equalizer adjustment value is used regardless of the difference. Can be fixed to one set value in some cases.

  As described above, the ratio FEnm, which is a value obtained by dividing the focus error signal by the total addition signal, is calculated, the thickness variation of the optical disc 2 is indirectly measured, and the value is set to the first threshold R1 or the first threshold value set in advance. Compared with the threshold value R2 of 2, the jitter of the reproduced waveform is reduced by selecting an appropriate value from the RF equalizer adjustment value table 41 previously set by learning and adjusting the RF equalizer when the allowable range is exceeded. Recording and reproduction performance can be improved.

1 is a block diagram showing a configuration of an optical disc recording / reproducing apparatus 1 to which the present invention is applied. The flowchart at the time of adjusting a focus offset or a focus balance. The figure which showed an example of the focus offset adjustment value table. The flowchart at the time of adjusting RF equalizer. The figure which showed an example of RF equalizer adjustment value table. The figure which showed typically the spot shape in the case of the optical disk of CD specification. The figure which showed typically the spot shape in the case of a dual disc. The figure which showed the relationship between the magnitude | size of a focus error signal, and the defocus amount.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical disk recording / reproducing apparatus 2 Optical disk ...
5 optical pickup 10 objective lens 13 modulation circuit 14 laser control circuit 15 semiconductor laser diode 22 photodetectors 24a to 24d adder 25 differential amplifier (OP1)
26 Focusing control circuit 27 Differential amplifier (OP2)
28 Tracking control circuit 29 Data reproduction circuit 30 PLL circuit 31 Bus 32 CPU
33 RAM
34 ROM
36 Interface circuit 37 Host device 38 Addition amplifier (OP3)
40 Focus offset adjustment value table 41 RF equalizer adjustment value table

Claims (4)

An optical pickup having an objective lens for condensing laser light on the information recording surface of the optical disc and a photodetector having a divided light receiving portion for receiving the reflected light from the optical disc;
A focus error signal generating means for generating a focus error signal from the output signal of the photodetector;
A full addition signal generating means for generating a full addition signal from the output signal of the photodetector;
A ratio calculating means for calculating a ratio between the focus error signal and the full addition signal;
Comparing means for comparing the ratio obtained by the ratio calculating means with a preset first threshold;
Focus offset adjustment means for setting a focus offset adjustment value for correcting a deviation amount between the focus point of the objective lens and the focus point due to the focus error signal according to the value calculated by the comparison means Optical disc recording / reproducing apparatus.   2. The optical disc recording / reproducing apparatus according to claim 1, further comprising focus offset adjustment value storage means for storing a plurality of predetermined focus offset adjustment values. An optical pickup having an objective lens for condensing laser light on the information recording surface of the optical disc and a photodetector having a divided light receiving portion for receiving the reflected light from the optical disc;
A focus error signal generating means for generating a focus error signal from the output signal of the photodetector;
A full addition signal generating means for generating a full addition signal from the output signal of the photodetector;
Reproduction signal generation means for generating a reproduction signal from the output signal of the photodetector; and ratio calculation means for calculating a ratio of the focus error signal and the full addition signal;
Comparing means for comparing the ratio obtained by the ratio calculating means with a preset first threshold;
An optical disc recording / reproducing apparatus comprising: an RF equalizer adjustment unit that sets an RF equalizer adjustment value that adjusts an amplitude of a high frequency component of the reproduction signal in accordance with a value calculated by the comparison unit.   4. The optical disc recording / reproducing apparatus according to claim 3, further comprising RF equalizer adjustment value storage means for storing a plurality of predetermined RF equalizer adjustment values.

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