JP2004171720A - Disk drive and disk discriminating method for the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make it possible to discriminate whether a DVD (Digital Versatile Disk) is for reproduction only or for recording and reproducing. <P>SOLUTION: In a step S2, a subtraction circuit 54 computes ((A+D)-(B+C)) which is a difference between detection signals. In steps S4 to S7, an addition circuit 55 computes the signal of ((A+D)+(B+C)) and outputs the signal to a low-pass filter 61. The low-pass filter 61 extracts a DC component from the signal and a normalization circuit 62 normalizes a track error signal based on the DC component. In steps S7 to S9, a disk discrimination section 63 discriminates the kind of the disk based on the computed value. The method is applicable to the case, for example, that the kind of a DVD (Digital Versatile Disk) is to be discriminated. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a disk drive and a disk determination method, and more particularly to a disk drive and a disk determination method capable of determining whether a disk is a read-only disk.
[0002]
[Prior art]
Recently, a DVD (Digital Versatile Disk) capable of recording a large amount of information by increasing its information recording density has become widespread.
[0003]
DVDs include, for example, a read-only type capable of only reproducing recorded information and a type (DVD-R, DVD-RW, DVD + RW, DVD + R, etc.) capable of recording as well as reproducing.
[0004]
In a read-only type DVD (hereinafter referred to as a DVD-ROM for convenience), information is recorded in uneven pits (embossed pits). On the other hand, a recordable DVD (hereinafter referred to as a DVD-RAM for convenience) has a groove (groove) to enable tracking even in a state where data is not recorded. Alternatively, information is recorded on lands (between grooves) or both grooves and lands.
[0005]
In order to record or reproduce a disc in an optimal state for each disc, it is necessary to determine the type of the disc. Several methods have been known for this purpose.
[0006]
The first method is a method of determining the type of an optical disk by using a ratio of a sum signal (PE signal) and a difference signal (FE signal) generated based on the reflected light of the disk (for example, see Patent Document 1). ).
[0007]
The second method is a method of detecting a signal corresponding to the amount of reflected light from an optical disk using light sources having different wavelengths, and discriminating the disk based on the signal corresponding to the amount of light (for example, Patent Document 2). reference).
[0008]
A third method is a method of detecting a reflectance of a different wavelength to determine a disc (for example, see Patent Document 3).
[0009]
The fourth method is a method of discriminating disks having different track pitches from the difference in the amount of reflected light (for example, see Patent Document 4).
[0010]
Further, discrimination of a disc from a wobble signal has also been proposed. That is, the data is already recorded on the read-only disc, and the recording position can be determined from, for example, the time stamp of the data, so that it is not necessary to record the track address information on the disc.
[0011]
On the other hand, on the recording / reproducing disk, track addresses are recorded by wobbling tracks (grooves) in order to be able to detect the position where data is recorded. Therefore, it has been proposed to determine whether a disc is dedicated to reproduction or recording / reproduction based on a wobble signal (signal of track address information).
[0012]
[Patent Document 1]
JP-A-2001-184676
[Patent Document 2]
JP-A-10-124914
[Patent Document 3]
JP-A-6-314465
[Patent Document 4]
JP-A-9-7197
[0013]
[Problems to be solved by the invention]
However, there is a problem that it is difficult to accurately determine whether a DVD-ROM or a DVD-RAM is used in a method of determining from the level of the reflected light, the presence or absence of a wobble signal, and the like. .
[0014]
In particular, the detection of the wobble signal requires a BPF (Band Pass Filter) having a narrow bandwidth and a narrow band, and thus not only increases the cost but also complicates the system.
[0015]
The present invention has been made in view of such a situation, and an object of the present invention is to enable disc type to be accurately determined.
[0016]
[Means for Solving the Problems]
A first disk drive device according to the present invention includes at least one pair of first light receiving means for receiving reflected light from a disk, and detecting reflected light from the disk received by the at least one pair of first light receiving means. A first calculating means for calculating a signal difference to generate a tracking error signal; and comparing a level of the tracking error signal generated by the first calculating means with a reference value, wherein a level of the tracking error signal is higher than the reference value. When the level is smaller, the disc is determined to be a read-only disc, and when the level of the tracking error signal is higher than a reference value, the discriminating means is determined to be a disc for recording and reproduction.
[0017]
The disk drive further includes normalizing means for normalizing the tracking error signal supplied to the discriminating means based on one detection signal of at least one pair of first light receiving means or a sum of the detection signals. The discriminating means can discriminate the disc type based on the tracking error signal normalized by the normalizing means.
[0018]
This disk drive device irradiates a first laser beam emitted to the center of a recording track of the disk and a first laser beam deviated by a predetermined distance from the recording track in the inner and outer peripheral directions of the disk. Generating means for generating the second laser light and the third laser light, at least one pair of second light receiving means for receiving the reflected light of the second laser light, and receiving the reflected light of the third laser light At least one pair of third light receiving means, second calculating means for calculating a difference between detection signals received by at least one pair of second light receiving means, and light received by at least one pair of third light receiving means A third calculating means for calculating a difference between the detected signals, a tracking error signal generated by the first calculating means based on a detection signal from the first light receiving means for receiving the first laser light, and a second Of the calculation means and the third The difference between the tracking error signal as a sum of the output of the calculation means, it is possible to further include a fourth calculating means for calculating a tracking error signal supplied to the determining means.
[0019]
The disk drive further includes normalizing means for normalizing the tracking error signal supplied to the discriminating means based on one detection signal of at least one pair of first light receiving means or a sum of the detection signals. The discriminating means can discriminate the disc type based on the tracking error signal normalized by the normalizing means.
[0020]
The disk discriminating method according to the present invention is characterized in that at least one pair of first light receiving steps for receiving reflected light from the disk and a difference between detection signals of reflected light from the disk received by the at least one pair of first light receiving steps. And calculating a tracking error signal, and comparing the level of the tracking error signal generated by the first calculation step with a reference value. When the level of the tracking error signal is smaller than the reference value, Determining a disc as a read-only disc, and discriminating the disc as a recording / playback disc when the level of the tracking error signal is higher than a reference value.
[0021]
In the present invention, the type of the disc is determined based on the tracking error signal.
[0022]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0023]
FIG. 1 shows the configuration of an embodiment of a disk drive device to which the present invention is applied. 1 includes a disk 2, a pickup 3, a reproduction signal processing unit 4, a servo unit 5, a feed motor 6, a spindle servo unit 7, a spindle motor 8, and a system controller 9.
[0024]
In the case of the present embodiment, the disk 2 is a read-only DVD or a recordable / reproducible DVD. The pickup 3 includes a semiconductor laser 31 (which will be described later with reference to FIG. 2) as a light source, a light receiving unit 36 (which will be described later with reference to FIGS. 2 and 3), and the like, and a laser beam emitted from the semiconductor laser 31. Is irradiated onto the disk 2 and the light reflected from the disk 2 is converted into an electric signal. Further, a tracking error signal and a reproduction RF signal are generated from the electric signal.
[0025]
The reproduction signal processing unit 4 processes the tracking error signal and the reproduction RF signal generated by the pickup 3. The configuration of the reproduction signal processing unit 4 will be described later with reference to FIG.
[0026]
The servo unit 5 generates a tracking servo signal based on the tracking error signal generated by the pickup 3, generates a focus servo signal based on the focus error signal generated from the pickup 3, and supplies the focus servo signal to the pickup 3. In addition, tracking control and focus control of the pickup 3 are performed. The servo unit 5 also generates a carriage control signal for moving the pickup 3 in the radial direction of the disk 2 based on the control from the system controller 9 or a tracking error signal, and outputs the signal to the feed motor 6.
[0027]
The feed motor 6 is driven based on a carriage control signal from the servo unit 5 and moves a pickup 3 in the radial direction of the disk 2 by driving a gear (not shown).
[0028]
The spindle servo unit 7 outputs a spindle servo signal based on a spindle control signal from the servo unit 5 so that the rotation speed of the disk 2 at the reading position of the pickup 3 on the disk 2 becomes a predetermined target speed. Generated data is output to the spindle motor 8 to control the rotation of the disk 2 via the spindle motor 8.
[0029]
The spindle motor 8 rotates the disk 2 based on a spindle servo signal output from the spindle servo unit 7.
[0030]
The system controller 9 communicates with a host computer (not shown) via an interface (not shown) and controls the overall operation of the disk drive 1.
[0031]
FIG. 2 shows the configuration of the pickup 3. 2 includes a semiconductor laser 31, a collimator lens 32, a half mirror 33, a mirror 34, an objective lens 35, and a light receiving unit 36.
[0032]
The semiconductor laser 31 generates a laser beam having a predetermined wavelength. The collimating lens 32 converts the incident diverging laser light into substantially parallel light. The half mirror 33 guides incident light to a mirror 34 described later, and guides reflected light to a light receiving unit 36 described later.
[0033]
The mirror 34 changes the direction of the incident light or the reflected light to a predetermined direction. The objective lens 35 irradiates the recording surface of the disk 2 with a laser beam focused on a predetermined beam diameter. The light receiving section 36 receives and detects the reflected light from the half mirror 33. The configuration of the light receiving unit 36 will be described later with reference to FIG.
[0034]
FIG. 3 shows a more detailed configuration of the light receiving unit 36.
[0035]
The light receiving unit 36 includes a photodetector 51, an addition circuit 52, an addition circuit 53, a subtraction circuit 54, and an addition circuit 55. A part or all of the addition circuit 52, the addition circuit 53, the subtraction circuit 54, and the addition circuit 55 may be arranged in the servo unit 5 or the reproduction signal processing unit 4.
[0036]
The photodetector 51 is divided into four detectors A, B, C, and D, and the reflected light reflected by the recording surface of the disk 2 and incident on the light receiver 36 is connected to each of the divided detectors. The current / voltage converters (not shown) convert the signals into electric signals and output the electric signals.
[0037]
The outputs of the detection unit A and the detection unit D are input to the addition circuit 52 and added. The outputs of the detection unit B and the detection unit C are input to the addition circuit 53 and added. Further, the output (A + D) of the addition circuit 52 and the output (B + C) of the addition circuit 53 are input to the subtraction circuit 54, and the subtraction of ((A + D)-(B + C)) is performed. The subtraction circuit 54 outputs the difference between the detection signals represented by ((A + D)-(B + C)) to the reproduction signal processing unit 4 as a tracking error signal.
[0038]
The outputs of the adder circuits 52 and 53 are also input to the adder circuit 55, where ((A + D) + (B + C)) is added. The addition circuit 55 outputs the sum of the detection signals represented by ((A + D) + (B + C)) to the reproduction signal processing unit 4 as a reproduction RF signal.
[0039]
FIG. 4 is a block diagram of the reproduction signal processing unit 4.
[0040]
The reproduction signal processing unit 4 includes a low-pass filter 61, a normalization unit 62, and a disc discrimination unit 63. The tracking error signal output from the subtraction circuit 54 is input to a normalization unit 62, and the reproduction RF signal output from the addition circuit 55 is input to a low-pass filter 61 and other circuits of the reproduction signal processing unit 4 (Not shown), processed, and then output to a circuit (not shown) at a subsequent stage. The low-pass filter 61 detects a low-frequency component (DC component) of the input reproduction RF signal and supplies the low-frequency component to the normalization unit 62. The normalization unit 62 normalizes the tracking error signal of the subtraction circuit 54 by dividing the tracking error signal by the output of the low-pass filter 61, and outputs the normalized tracking error signal to the disc discrimination unit 63. The disc discriminator 63 compares the magnitude of the tracking error signal input from the normalizer 62 with a predetermined reference value, and discriminates the disc type based on the comparison result.
[0041]
Next, the disc determination process will be described with reference to the flowchart of FIG. This processing is executed when the disk 2 is mounted on the disk drive device 1 and before a reproduction or recording command is input from the user.
[0042]
In step S1, when the disk 2 is mounted on the disk drive 1, the system controller 9 controls the spindle servo unit 7 via the servo unit 5 and causes the spindle motor 8 to rotate the disk 2.
[0043]
In addition, the system controller 9 controls the pickup via the servo unit 5 and causes the semiconductor laser 31 to generate laser light.
[0044]
The laser light is converted into substantially parallel light by the collimator lens 32, and enters the objective lens 35 via the half mirror 33 and the mirror 34. The objective lens 35 irradiates the recording surface of the disk 2 with laser light.
[0045]
Light reflected from the disc 2 is incident on the photodetector 51 via the objective lens 35, the mirror 34, and the half mirror 33. The addition circuit 52 adds the outputs of the detection units A and D of the photodetector 51. The addition circuit 53 adds the outputs of the detection unit B and the detection unit C of the photodetector 51.
[0046]
In step S2, the subtraction circuit 54 calculates the difference between the output of the addition circuit 53 from the output of the addition circuit 52. In FIG. 3, the track direction is a direction indicated by an arrow T in the figure. Therefore, ((A + D)-(B + C)) which is the calculated value of the difference between the detection signals obtained by the subtraction circuit 54 is a push-pull tracking error signal. The subtraction circuit 54 outputs the tracking error signal to the normalization unit 62 in step S3. Although detailed description is omitted, in this state, the servo unit 5 controls the focus of the pickup 3. However, the tracking servo remains off. Therefore, since the disk 2 is generally eccentric, the tracking error signal is a signal that changes in a sinusoidal manner between a positive peak and a negative peak.
[0047]
In step S4, the addition circuit 55 calculates the signal of ((A + D) + (B + C)) by adding the outputs of the addition circuits 52 and 53, and outputs the signal to the low-pass filter 61 as an RF signal. In step S5, the low-pass filter 61 calculates an RF signal and extracts a DC component. In step S6, the normalization unit 62 normalizes the tracking error signal by dividing the tracking error signal from the subtraction circuit 54 by the DC component from the low-pass filter. Note that any one of the detection units A to D may be used as a signal for normalizing the tracking error signal. Further, the normalizing section 62 may be omitted in principle. This normalization makes it possible to determine the type of disk without being affected by variations in disk characteristics.
[0048]
In step S7, the discrimination unit 63 sets the calculated value to a predetermined reference value based on the calculated value (value obtained by normalizing the absolute value of the peak value of the tracking error signal) input from the normalizing unit 62. It is determined whether it is greater than. If the calculated value is smaller than the predetermined reference value (if the positive peak value is smaller than the reference value or the negative peak value is larger than the reference value), the process proceeds to step S8, where the calculated value is smaller than the predetermined reference value. If the value is larger than the value (the positive peak value is larger than the reference value or the negative peak value is smaller than the reference value), the process proceeds to step S9.
[0049]
In step S8, the disk determination section 63 determines the type of the disk as a read-only disk, and outputs a determination result to the system controller 9. At this time, the system controller 9 allows only the reproduction process for the disc 2 and prohibits the recording process in response to a command from the user. In step S9, the disc discrimination unit 63 discriminates the disc type as a recording / playback disc, and outputs the discrimination result to the system controller 9. At this time, the system controller 9 permits not only the data reproduction processing but also the recording processing on the disk 2.
[0050]
Note that the processing (normalization processing) of steps S4 to S6 in the above-described disc determination processing can be omitted in principle. Of course, performing the normalization processing enables more accurate discrimination.
[0051]
This determination is based on the following principle. That is, the recording / reproducing disk has a groove or land depth of λ / 8 (where λ is the wavelength of the laser beam) so that tracking control can be performed even when data is not recorded. As shown in FIG. 6, the level of the tracking error signal (push-pull signal) becomes maximum when the depth of the groove or land (pit) is λ / 8.
[0052]
On the other hand, the DVD read-only disc has a pit depth of λ / 8, so that the level of the tracking error signal is smaller than that of the recording / playback disc. Therefore, the disc type can be determined by setting an intermediate value between the two as the threshold value.
[0053]
The level of the RF signal is maximum at a depth of λ / 4. Therefore, by performing normalization using the DC component of the RF signal, more accurate determination can be performed. In particular, a recording / reproducing disc on which no data is recorded has a smaller DC component, so that the normalized value is larger. Therefore, more accurate discrimination becomes possible.
[0054]
FIG. 7 shows another embodiment of the present invention. In this embodiment, a diffraction grating 71 is arranged on the pickup 3.
[0055]
The diffraction grating 71 is provided between the collimator lens 32 and the half mirror 33. The laser light emitted from the semiconductor laser 31 is divided into three by the diffraction grating 71 into a total of three laser lights of a main beam as a zero-order light and two side beams as ± first-order lights.
[0056]
FIG. 8 shows the irradiation positions on the disk 2 of the main beam, the + 1st-order light, and the -1st-order light divided by the diffraction grating 71. The main laser beam 201 is turned on (tracks formed on at least one of a groove and a land (pits are formed in the example of FIG. 8, but no pits (or marks) are formed). Is also illuminated). On the other hand, the + 1st-order light 202 is applied to a position shifted by 1/2 track pitch toward the inner circumference of the disk 2, and the −1st-order light 203 is applied to the outer circumference of the disk 2 Irradiation is performed at a position shifted by the track pitch.
[0057]
In this case, as shown in FIG. 9, the light receiving unit 36 includes a first photodetector 91, a second photodetector 92, a third photodetector 93, an addition circuit 94, an addition circuit 95, a subtraction circuit 96, a subtraction circuit 97, It comprises a subtraction circuit 98, an addition circuit 99, a subtraction circuit 100, and an addition circuit 101. Of course, part or all of the addition circuit 94, the addition circuit 95, the subtraction circuit 96, the subtraction circuit 97, the subtraction circuit 98, the addition circuit 99, the subtraction circuit 100, and the addition circuit 101 may be replaced by the servo unit 5 or the reproduction signal processing. You may make it arrange | position in the part 4.
[0058]
The first photodetector 91 is divided into four detectors A to D, the second photodetector 92 is divided into two detectors E and F, and the third photodetector 93 is divided into G And H are divided into two detection units.
[0059]
Of the three laser beams split by the diffraction grating 71, the reflected beam of the main laser beam 201 is received by the first photodetector 91, and the reflected beam of the + first order light 202 is received by the second photodetector 92. , -1st order light 203 is received by the third photodetector 93. The track direction is a direction indicated by an arrow T.
[0060]
The outputs of the detectors A and D and the outputs of the detectors B and C of the first photodetector 91 are input to the adder circuit 94 or the adder circuit 95, respectively, where (A + D) and (B + C) are added. . The outputs of the detectors E and F of the second photodetector 92 are input to a subtraction circuit 96, where (EF) is subtracted. The outputs of the detectors G and H of the third photodetector 93 are input to a subtraction circuit 97, where (GH) is subtracted.
[0061]
Outputs from the addition circuits 94 and 95 are input to a subtraction circuit 98, where subtraction of ((A + D)-(B + C)) is performed. Outputs from the subtraction circuit 96 and the subtraction circuit 97 are output to an addition circuit 99, where (K × {(E−F) + (G−H)}) is added. Further, the outputs from the subtraction circuit 98 and the addition circuit 99 are input to the subtraction circuit 100, and the subtraction of ((A + D)-(B + C) -K * {(EF) + (GH)}) is performed. Is
[0062]
The subtraction circuit 100 reproduces the difference between the detection signals represented by ((A + D)-(B + C) -K * {(EF) + (GH)}) as a differential push-pull tracking error signal. Output to the signal processing unit 4.
[0063]
The outputs from the adder circuits 94 and 95 are also input to the adder circuit 101, where the addition of ((A + D) + (B + C)) is performed. The addition circuit 101 outputs the sum of the detection signals represented by ((A + D) + (B + C)) to the reproduction signal processing unit 4 as a reproduction RF signal.
[0064]
The configuration of the reproduction signal processing unit 4 is the same as the configuration shown in FIG. However, the subtraction circuit 54 for outputting the tracking error signal to the normalization unit 62 and the addition circuit 55 for outputting the reproduction RF signal to the low-pass filter 61 and the reproduction processing unit 4 and other circuits in FIG. In the case of the form, they are a subtraction circuit 100 and an addition circuit 101, respectively.
[0065]
With reference to the flowchart of FIG. 10, the disc determination processing in the case of the embodiment of FIG. 9 will be described. This processing is executed when the disk 2 is mounted on the disk drive device 1 and before a reproduction or recording command is input from the user.
[0066]
In step S21, when the disk 2 is mounted on the disk drive 1, the system controller 9 controls the spindle servo unit 7 via the servo unit 5 and causes the spindle motor 8 to rotate the disk 2.
[0067]
In addition, the system controller 9 controls the pickup via the servo unit 5 and causes the semiconductor laser 31 to generate laser light.
[0068]
The laser light is converted into substantially parallel light by the collimator lens 32, and enters the objective lens 35 via the half mirror 33 and the mirror 34. The objective lens 35 irradiates the recording surface of the disk 2 with laser light.
[0069]
The reflected light from the disk 2 is incident on the first photodetector 91, the second photodetector 92, and the third photodetector 93 via the objective lens 35, the mirror 34, and the half mirror 33. First, in the photodetector 91, an addition circuit 94 adds the outputs of the detection units A and D of the first photodetector 91, and an addition circuit 95 outputs the outputs of the detection units B and C of the first photodetector 91. Is added. Second, in the photodetector 92, a subtraction circuit 96 subtracts the outputs of the detection units E and F of the second photodetector 92. In the third photodetector 93, a subtraction circuit 97 subtracts the outputs of the detection units G and H of the third photodetector 93.
[0070]
In step S22, the subtraction circuit 98 calculates the difference between the outputs of the addition circuit 95 from the output of the addition circuit 94, obtains the calculated value of the difference between the detection signals ((A + D)-(B + C)), and calculates the calculated value. Is output to the subtraction circuit 100. In step S23, the addition circuit 99 calculates the sum of the output of the subtraction circuit 96 and the output of the subtraction circuit 97 to obtain the sum of the detection signals ((EF) + (GH)). A value obtained by multiplying the value by K (K × {(E−F) + (G−H)}) is output to the subtraction circuit 100. In step S24, the subtraction circuit 100 calculates the difference between the output of the subtraction circuit 98 and the output of the addition circuit 99. In FIG. 9, the track direction is a direction indicated by an arrow T in the figure. Therefore, the calculated value of the difference between the detection signals obtained by the subtraction circuit 100 ((A + D)-(B + C) -K * {(EF) + (GH)}) is tracking by the differential push-pull method. Error signal. The subtraction circuit 100 outputs the tracking error signal to the normalization unit 62 in step S25.
[0071]
In step S26, the addition circuit 101 calculates the signal of ((A + D) + (B + C)) by adding the outputs of the addition circuit 94 and the addition circuit 95, and outputs the signal to the low-pass filter 61 as an RF signal. In step S27, the low-pass filter 61 calculates an RF signal and extracts a DC component. In step S28, the normalization unit 62 normalizes the tracking error signal by dividing the tracking error signal from the subtraction circuit 100 by the DC component from the low-pass filter. Of course, it is also possible to use any one of the detection units A to D as a signal for normalizing the tracking error signal. Further, the normalizing section 62 may be omitted in principle.
[0072]
In step S29, based on the calculated value (value obtained by normalizing the absolute value of the peak value of the tracking error signal) input from the normalizing unit 62, the discriminating unit 63 sets the calculated value to a predetermined reference value. It is determined whether it is greater than. If the calculated value is smaller than the predetermined reference value (if the positive peak value is smaller than the reference value or the negative peak value is larger than the reference value), the process proceeds to step S30, where the calculated value is smaller than the predetermined reference value. If the value is larger than the value (the positive peak value is larger than the reference value or the negative peak value is smaller than the reference value), the process proceeds to step S31.
[0073]
In step S30, the disk determination section 63 determines the type of the disk as a read-only disk, and outputs the determination result to the system controller 9. At this time, the system controller 9 allows only the reproduction process for the disc 2 and prohibits the recording process in response to a command from the user. In step S31, the disc discrimination unit 63 discriminates the disc type as a recording / playback disc, and outputs the discrimination result to the system controller 9. At this time, the system controller 9 permits not only the data reproduction processing but also the recording processing on the disk 2.
9 controls the drive of the disk 2 based on the determination result.
[0074]
Note that, similarly to the processing in steps S4 to S6 in FIG. 5, the processing in steps S26 to S28 (normalization processing) in the disc determination processing described above can be omitted in principle.
[0075]
In the above description, the type of the DVD is determined. However, the present invention can be applied to a case where a CD other than the DVD and other optical disks are determined.
[0076]
Further, the signal output from the subtraction circuit 54 or the subtraction circuit 100 is a tracking error signal, but whether or not this signal is used for actual tracking servo is arbitrary. That is, the tracking error signal used for the tracking servo may be different from the tracking error signal used for disc determination. Of course, the configuration is simpler if both are set to the same tracking error signal.
[0077]
【The invention's effect】
As described above, according to the present invention, it is possible to discriminate between a read-only disc and a recording / playback disc. Further, it is possible to distinguish between a read-only disk and a recording / reproducing disk without significantly changing the existing system of the disk drive device. Further, it is possible to reduce the size of the disk drive device and suppress an increase in cost.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating a configuration of a disk drive device.
FIG. 2 is a diagram illustrating a configuration of a pickup of FIG. 1;
FIG. 3 is a diagram illustrating a configuration of a light receiving unit in FIG. 2;
FIG. 4 is a block diagram illustrating a configuration of a reproduction signal processing unit in FIG. 1;
FIG. 5 is a flowchart illustrating a disc discriminating process when the configuration of the light receiving unit in FIG.
FIG. 6 is a diagram illustrating the relationship between the depth of a pit and the output levels of a tracking error signal and a reproduced RF signal.
FIG. 7 is a diagram showing a configuration of the pickup of FIG. 1 in another embodiment of the present invention.
FIG. 8 is a diagram illustrating laser light divided into three.
FIG. 9 is a diagram illustrating a configuration of a light receiving unit in FIG. 2 according to another embodiment of the present invention.
FIG. 10 is a flowchart illustrating a disk determination process according to another embodiment of the present invention.
[Explanation of symbols]
1 disk drive, 2 disk, 3 pickup, 4 playback signal processing unit, 5 servo unit, 6 feed motor, 7 spindle servo unit, 8 spindle motor, 9 system controller, 31 semiconductor laser, 32 collimating lens, 33 half mirror, 34 mirror, 35 objective lens, 36 light receiving section, 51 photo detector, 61 LPF, 62 normalizing section 62, 63 disk discriminating section, 71 diffraction grating, 91 first photo detector, 92 second photo detector, 93 third photo detector

Claims (5)

In a disk drive for driving a disk,
At least one pair of first light receiving means for receiving reflected light from the disk;
First calculating means for calculating a difference between detection signals of reflected light from the disk received by at least one pair of the first light receiving means and generating a tracking error signal;
Comparing the level of the tracking error signal generated by the first calculating means with a reference value, and when the level of the tracking error signal is smaller than the reference value, discriminating the disc as a read-only disc; A disc drive device comprising: a discriminating means for discriminating the disc as a recording / reproducing disc when an error signal level is higher than the reference value. A normalization unit that normalizes the tracking error signal supplied to the determination unit based on at least one pair of one detection signal of the first light receiving unit or a sum of the detection signals;
2. The disk drive according to claim 1, wherein the determination unit determines the type of the disk based on the tracking error signal normalized by the normalization unit. A first laser beam applied to the center of a recording track of the disk, and a second laser beam applied to the recording track while being deviated by a predetermined distance in an inner circumferential direction and an outer circumferential direction of the disk. Generating means for generating light and a third laser light;
At least one pair of second light receiving means for receiving reflected light of the second laser light,
At least one pair of third light receiving means for receiving reflected light of the third laser light,
Second calculating means for calculating a difference between at least one pair of detection signals received by the second light receiving means;
Third calculating means for calculating a difference between the detection signals received by at least one pair of the third light receiving means;
A tracking error signal generated by the first calculating means based on a detection signal of the first light receiving means for receiving the first laser light; an output of the second calculating means; 4. The disk drive according to claim 1, further comprising: fourth calculating means for calculating the tracking error signal to be supplied to the discriminating means from a difference from a tracking error signal as a sum of outputs of the means. apparatus. A normalization unit that normalizes the tracking error signal supplied to the determination unit based on at least one pair of one detection signal of the first light receiving unit or a sum of the detection signals;
4. The disk drive according to claim 3, wherein the determination unit determines the type of the disk based on the tracking error signal normalized by the normalization unit. In a disk discriminating method of a disk drive for driving a disk,
At least one pair of first light receiving steps of receiving light reflected from the disk;
A first calculation step of calculating a difference between detection signals of reflected light from the disk received by at least one pair of the first light reception steps and generating a tracking error signal;
Comparing the level of the tracking error signal generated in the first calculation step with a reference value, and when the level of the tracking error signal is smaller than the reference value, discriminating the disc as a read-only disc; Discriminating the disc as a recording / playback disc when the level of the error signal is greater than the reference value.

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