JPH04355221A - optical disc device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disc device capable of recording and reproducing information.

0002

2. Description of the Related Art In recent years, in addition to playback-only optical disk devices such as CD players, there has been active development of recordable optical disks and their recording/playback devices. The recording density of optical disks is extremely high, and information is recorded in concentric circles or spiral tracks with a pitch of about 1.6 μm. Therefore, highly accurate device control that allows the laser spot to stably and accurately follow such tracks is essential for recording and reproducing information.

[0003] Therefore, recordable optical discs are generally provided with concentric or spiral continuous grooves as guide grooves, and tracking control of the laser spot is performed based on these grooves. Information is recorded in the guide grooves or between the guide grooves as the uneven shape of the substrate or as changes in the optical properties of the recording film. A tracking control means called a so-called push-pull method is applied to such an optical disc (hereinafter referred to as a first type of optical disc). (Hereinafter, this will be referred to as the first tracking control means.) Also, optical discs with such guide grooves are coated with different recording films depending on the recording method, but in general, rewritable discs have low reflectance. , those that can be recorded only once have a high reflectance.

On the other hand, on read-only optical discs, information is recorded as an array of uneven pits on the base, and these form concentric or spiral information tracks, with no guide grooves. Tracking of the laser spot is performed on this information track. A tracking control means for such an optical disc (hereinafter referred to as a second type of optical disc) is disclosed in, for example, Japanese Patent Laid-Open No. 52-9
3222 or JP-A-57-181433 (hereinafter referred to as the second tracking control means). Such optical discs generally have higher reflectance than rewritable optical discs.

[0005] Hereinafter, a conventional technique relating to an optical disc device having a focusing control means and a tracking control means constructed using a four-division light receiving element will be explained.

First, an optical head optical system commonly applied to the two types of tracking control means will be explained. FIG. 4a is a layout diagram of such an optical head optical system. In FIG. 4a, the light beam emitted from the semiconductor laser 52 is made into a parallel light beam by the collimator lens 51, reflected by the half mirror 3 disposed at an angle of 45 degrees in the optical path, and then reflected by the objective lens 2 into the optical disk 1. It is focused on the recording surface. The light beam reflected from the recording surface of the optical disk 1 is made into a parallel light beam again by the objective lens 2, passes through the half mirror 3, and is guided to the four-split light receiving element 6 by the condenser lens 4 and the cylindrical lens 5. The four-division light-receiving element 6 is placed at a position where the received light beam, which is made into an astigmatic light beam by the cylindrical lens 5, becomes a circle of least confusion when the laser beam is focused on the recording surface of the optical disc, and the axis of the cylindrical lens 5 is , are placed at an angle of 45 degrees with the dividing line of the four-divided light-receiving element 6. As shown in FIG. 4b, each component of the four-division light receiving element 6 is designated S1, S2, S3, and S4, and the photoelectric conversion outputs thereof are also designated by the same reference numerals.

Next, the features of the first tracking control means and the structure of a conventional optical disc device constructed using the same will be explained with reference to FIG. FIG. 5 is a block diagram of the main parts of such an optical disc device. 7,
Reference numerals 9 and 11 each indicate an amplifier capable of adding, and when the sign written on the input terminal is positive, the signals are added in positive phase, and when the sign written on the input terminal is negative, the signals are added and amplified in reverse phase. 6 is 4 shown in Figure 4.
It is a split light receiving element, and the output of each component is sent to an amplifier 7,
9 and 11. The output of the amplifier 7 is a signal FE expressed by the following equation

[0008]

[Math 1]

This is sent to the focusing control section 8 as a focusing error signal. The output of the amplifier 9 is a signal TE1 expressed by the following equation.

0010

[Math 2]

##EQU1## This is sent to the tracking control section 10 as a tracking error signal. The output of the amplifier 11 is a signal AS expressed by the following equation

0012

[Math 3]

Since this signal contains information recorded on the optical disc, it is sent to the information signal detection section 12.

The reason why the signal TE1 is obtained will now be explained. Since the first type of optical disk has a guide groove, tracking is performed by the first tracking control means based on the guide groove. FIG. 9 shows that, depending on the position of the laser spot with respect to the continuous guide groove,
3 shows how the light amount distribution of reflected light on the pupil of the objective lens 2 shown in FIG. The track direction is perpendicular to the plane of the paper. As shown in the figure, when the laser spot deviates from the track, the light amount distribution becomes asymmetrical about the center line of the objective lens 2 that is parallel to the track. On the other hand, the center line perpendicular to the pupil track is symmetrical because the guide groove is continuous. In FIG. 4a, the four-split light receiving element 6 is divided into two directions: the direction in which the center line parallel to the pupil track is transformed by the light receiving optical system, the dividing line between its components S1 and S2, and the dividing line between the components S1 and S2;
Since the dividing lines of and S4 are arranged so that they correspond,
A photoelectric conversion output dependent on a symmetrical light intensity distribution is generated in each component of the four-division light receiving element 6. This is (Math. 2)
This means that the value of the signal TE1 defined in (1) is zero when there is no track deviation, and when there is a track deviation, it takes a positive or negative value depending on the amount and direction. Figure 10 shows
It shows the response of the signal TE1 to the amount of track deviation of the laser spot. In the figure, the horizontal axis of the graph represents the amount of track deviation, and the vertical axis represents the intensity of the signal TE1. From the above, the feature of the first tracking control means is to obtain the tracking error signal TE1 from a pair of outputs that produce an intensity difference according to the track deviation among the photoelectric conversion outputs of each component of the 4-split light receiving element. It can be said that

Next, the features of the second tracking control means and the structure of a conventional optical disc device constructed using the second tracking control means will be explained with reference to FIG. FIG. 6 is a block diagram of the main parts of such an optical disc device. Figure 5
Components common to those shown in are given the same numbers and detailed explanations will be omitted. Outputs S1 and S3 of each component of the four-division light receiving element 6 are input to an amplifier 13, and outputs S2 and S4
is input to the amplifier 14. Assuming the output of the amplifier 13 as the signal P1, the following formula

[0016]

[Math 4]

##EQU1## The output of the amplifier 14 is assumed to be a signal P2 and is expressed by the following equation.

[0018]

[Math 5]

The subtracter 15 subtracts the signal P from the signal P1.
2 is subtracted, resulting in a focusing error signal equivalent to the signal FE, which is sent to the focusing control section 8. Further, the phase difference between the signals P1 and P2 is detected by the phase difference detection section 16, and the detected phase difference is detected by the conversion section 1.
7, the tracking error signal is converted into a voltage corresponding to the amount of phase difference, and is sent to the tracking control unit 10 as a tracking error signal similar to the signal TE1 (hereinafter, the tracking error signal obtained in this way will be referred to as PTE).

The cause of the phase difference between the signals P1 and P2 will now be explained. Since the second type of optical disk does not have a guide groove, tracking is performed by the second tracking control means based on uneven pits distributed on the track. FIG. 11 shows the difference in the light amount distribution of the reflected light on the pupil of the objective lens 2 shown in FIG. 4a, which is caused by the positional relationship between the pit and the laser spot. In FIG. 11, column b shows the case where there is no track deviation, and columns a and c show the case where the track shifts to the left and right. In each column, the positions of pits and laser spots and the light amount distribution of reflected light generated at the positions on the pupil of the objective lens 2 are shown. Code t1 written on the left side
, t2, and t3 correspond to the times in which the pit passes the laser spot. At times t1 and t3, the light intensity distributions of columns a and c at each time are mirror symmetrical to each other in the direction parallel to the track, and are asymmetrical to each other in the direction perpendicular to the track. Therefore, Figure 11d
If the pupil of objective lens 2 is divided as shown in the figure, areas A1 and A
There is a time lag in the change between the sum of the amounts of light passing through area A2 and the sum of the amounts of light passing through areas A2 and A4, and furthermore,
It can be seen that when the direction of the track shift changes, the time shift occurs in the opposite direction. In addition, because the optical system shown in FIG. 4a guides the light intensity distribution on the pupil of the objective lens 2 to the four-split light receiving element 6 while preserving the symmetry, the photoelectric conversion output depending on this light intensity distribution is divided into four parts. This occurs in each component of the light receiving element 6. Therefore, a phase difference in polarity depending on the direction of the track deviation occurs in the signals P1 and P2 defined by (Equation 4) and (Equation 5). The signal PTE, which is made up of a voltage according to the amount of phase difference between these signals P1 and P2, is
Similarly, the response shown in FIG. 10 will be shown. From the above, the feature of the second tracking control means is that the phase difference between the pair of outputs P1 and P2, which generates a phase difference according to the track deviation, among the photoelectric conversion outputs of each component of the 4-split light receiving element 6 is This can be said to be the creation of a tracking error signal based on the tracking error signal.

The operations of the two types of conventional optical disk devices configured as described above will be explained below. FIG. 7 shows the shape of the light beam on the four-split light receiving element 6 that changes depending on the focus state of the optical head, and FIG.
is a graph of signal FE. In FIG. 8, the horizontal axis represents the amount of defocus, and the vertical axis represents the intensity of the signal FE. first,
As a common operation for both, when the focus point of the optical head is brought closer to the rotating optical disk, the received light beam is divided into four parts on the four-split light receiving element 6 due to the surface vibration of the optical disk, as shown in FIG.
a, FIG. 7b, and FIG. 7c. When the laser beam is focused on the optical disk, this beam becomes circular as shown in FIG. 7b, and when it is defocused back and forth, it becomes elliptical as shown in FIG. 7a or 7c. Therefore, FIG. 5 obtained as the signal FE defined by (Equation 1)
The output of amplifier 7 in or subtractor 1 in FIG.
The output of No. 5 shows a response as shown in FIG. 8 with respect to the defocus amount. The focusing control section 8 in FIGS. 5 and 6 performs focusing control of the optical head so that this signal FE becomes zero.

Next, tracking of the laser spot is performed to follow the movement of the track caused by eccentricity of the optical disk or the like. As mentioned above, for the first type of optical disc, the tracking error signal TE1 is obtained by the first tracking control means, and for the second type of optical disc, the tracking error signal TE1 is obtained by the second tracking control means. PTE is obtained. These tracking error signals TE1 or PTE are shown in Figure 5.
The signals are then sent to each tracking control unit 10 in FIG. 6, and the tracking control unit 10 controls the position of the laser spot so that these signals become zero.

When stable focusing control and tracking control are performed in this manner, the information recorded on the optical disc and included in the output AS of the amplifier 11 in FIGS. 5 and 6 can be detected by the information signal detection section 12.

[0024]

[Problems to be Solved by the Invention] However, in the above-mentioned conventional technology, for continuous grooves, there is no phase difference between the signals P1 and P2 due to the above-mentioned symmetry of the reflected light. It is difficult to track the guide groove of the optical disc using the second tracking control means. On the other hand, the signal TE1 is generated because the interference state of the light diffracted by the track groove differs depending on the positional relationship between the laser spot and the groove, so the amplitude of TE1 is as follows.
It is known that the depth of the groove is maximum when it is λ/8 (λ: the wavelength of the laser beam) and becomes zero when it is λ/4. Usually, the depth of the guide groove of the first type of optical disc is λ/8, and the depth of the unevenness of the track of the second type of optical disc is λ/4 to λ/6. For the type of optical disc, the amplitude of the signal TE1 obtained by the first tracking control means becomes small, making stable tracking control difficult.

That is, the conventional tracking control means has a problem in that it is not possible to stably track both types of optical discs, that is, recordable optical discs and read-only optical discs such as CDs. Therefore, there has been no common use of reproducing devices for such optical discs.

[0026] The present invention solves the above problems.
An object of the present invention is to provide an optical disc device that can perform stable and accurate tracking control regardless of whether or not a guide groove is present on the optical disc.

[0027]

[Means for Solving the Problems] To achieve this object, a first optical disc device according to the present invention includes a plurality of different tracking control means that operate by detecting reflected light from grooves formed in tracks of an optical disc. The tracking control means has a configuration comprising: means for detecting the depth of the groove; and means for selecting one tracking control means from a plurality of different tracking control means according to the detected groove depth information.

The second optical disc device also includes a plurality of different tracking control means that operate by detecting reflected light from grooves formed in the tracks of the optical disc, and means for detecting the reflectance of the recording surface of the optical disc. and means for selecting one of the plurality of different tracking control means according to the detected reflectance information.

Furthermore, the third optical disk device includes a plurality of different tracking control means that operate by detecting reflected light from grooves formed in the tracks of the optical disk, and a laser spot that is controlled by each of the plurality of different tracking control means. The device has a configuration including means for detecting the amplitude of a tracking error signal generated when the tracking error signal traverses the traverse, and means for selecting one from a plurality of different tracking control means according to the detected amplitude.

[0030]

[Operation] According to the above-described structure, the present invention selects a tracking control means suitable for the optical disc to be played from among a plurality of different tracking control means prepared, and switches to a structure that operates with that means. Stable and accurate tracking is possible regardless of the type of optical disc.

[0031]

Embodiments (Embodiment 1) A first embodiment of the present invention will be described below with reference to the drawings. The optical system of the optical head of this embodiment has the configuration shown in FIG. 4a, similar to the prior art example described above, and therefore a description thereof will be omitted.

FIG. 1 is a block diagram of the main parts of the optical disc device in this embodiment. In FIG. 1, the four-division light receiving element 6 is arranged in the same manner as described in the conventional example with respect to the optical system shown in FIG. 4a. Therefore, from each component of the 4-split light receiving element 6, the photoelectric conversion output explained in the first tracking control means is obtained for the first type of optical disk, and the photoelectric conversion output as explained in the first tracking control means is obtained from each component of the 4-division light receiving element 6. 2
The photoelectric conversion output described in the tracking control means is generated. In FIG. 1, a four-division light receiving element 6, a focusing control section 8, an amplifier 9, a tracking control section 1
0, amplifier 11, information signal detection section 12, amplifier 13, 1
4. The subtracter 15, the phase difference detection section 16, and the conversion section 17 are the same components as those shown in FIGS. 5 and 6 in the description of the prior art, so detailed explanations will be omitted. The output TE1 of the amplifier 9 is a tracking error signal used by the first tracking control means, and is input to the calculation section 18. The output AS of the amplifier 11 is input to the arithmetic unit 18, and the arithmetic unit 18 performs division on the signal TE1 with AS as the denominator,
The following signal TE2

[0033]

[Math 6]

Outputs . Since the signal AS is a photoelectric conversion output corresponding to the total amount of received light, the signal TE2 obtained by this calculation is a signal that reflects the depth and shape of the track groove, which is not affected by the difference in reflectance of the recording surface of the optical disk. . The signal TE2 is compared with a predetermined value by the comparator 19, and the comparator 19 gives an instruction to the selector 20 based on the comparison result. The outputs P1 and P2 of the amplifiers 13 and 14 are processed in the same manner as shown in FIG.
The focusing error signal FE generated at the output of the subtracter 15 is sent to the focusing control section 8. The selector 20 is connected to the comparator 19 or the system controller 21.
Select signal PTE or TE2 according to the instructions from
Either one is sent to the tracking control section 10. The focusing control section 8 and the tracking control section 10 perform focusing control and tracking control of the laser spot based on the signals input to each. The signal AS is sent to the information signal detection section 12, and the information recorded on the optical disc is detected. The system controller 21 grasps the states of the focusing control section 8, tracking control section 10, calculation section 18, and selector 20 and controls them.

The operation of this embodiment configured as described above will be explained below. When an optical disc is inserted into the apparatus, the system controller 21 first prompts the focusing control unit 8 to focus the laser beam on the recording surface of the optical disc. After confirming that stable focusing control is being performed, the system controller 21
The tracking controller 10 is controlled to forcibly move the laser spot in a direction perpendicular to the track. This causes the signal TE2 to oscillate each time the laser spot crosses the track. The comparator 19 uses this signal TE.
Check the amplitude of 2 and determine whether it is larger or smaller than the default value. If it is larger, use signal TE2, and if smaller, use signal PTE.
An instruction is given to the selector 20 to output this to the tracking control section 10. Since the amplitude of the signal TE2 reflects the depth of the track groove, by determining the magnitude of the amplitude in this way, it is possible to distinguish between the guide groove with a depth of λ/8 and the depth of λ.
A distinction can be made between grooves with depths ranging from /4 to λ/6. In other words, it is possible to distinguish between a first type of optical disc, which is an optical disc with a guide groove, and a second type of optical disc, which is an optical disc without a guide groove.

In this way, when the appropriate tracking control means for the optical disc to be played is selected, the system controller 21 stops forcing the tracking control section 10, and the selector 20
outputs either the signal PTE or TE2 to the tracking control section 10 according to the selection. The tracking control unit 10 tracks the laser spot on the track of the optical disc based on this input signal. Further, the selected path of the selector 20 is held until instructed by the system controller 21, and when another optical disk is newly inserted into the device, the system controller 21 uses the above-mentioned method to determine the type of optical disk. Repeat the action.

As described above, according to the optical disk device of the first embodiment of the present invention, playback is performed by comparing the magnitude of the amplitude of the fluctuation that occurs in the signal TE2 when the laser spot crosses the track with a predetermined value. By determining the type of optical disc to be used and switching to a control circuit that operates with tracking control means suitable for that optical disc, it is possible to configure an optical disc device that performs stable and accurate tracking control regardless of the type of optical disc. can.

(Embodiment 2) A second embodiment of the present invention will be described below with reference to FIG. FIG. 2 is a block diagram of the main parts of the configuration of this embodiment. The configuration of the optical head, which is part of the optical disc device configuration of this embodiment, is as follows:
Since it consists of the structure shown in FIG. 4a explained in the first embodiment, the explanation will be omitted. In FIG. 2, constituent elements labeled with the same numbers as in FIG. 1 are the same as those in the first embodiment, so detailed explanations will be omitted. The difference from FIG. 1 is the calculation unit 1.
8 is replaced by a peak hold section 22. The output FE of the subtracter 15 is input to the peak hold section 22, where the peak value is detected. The detected peak value is compared with a predetermined value in the comparison section 23, and the comparison section 23 sends an instruction to the selector 20 based on the comparison result. The output TE1 of the amplifier 9 is directly led to the selector 20, and the output of the amplifier 11 is sent only to the information signal detection section. The selector 20 selects the input signals TE1 and PTE based on instructions from the comparator 19 or the system controller 21,
Either one is sent to the tracking control section 10.

The operation of this embodiment configured as described above will be explained below. Since its operation is also generally the same as that of the first embodiment, only the differences will be explained with reference to FIG. 2. First, when the spot position is brought closer to focus the laser beam on the recording surface of the optical disk, the focusing error signal FE exhibits an S-shaped response with two peaks as shown in FIG. The peak hold section 22 detects one or both of the peak values m1 and m2. As is clear from the definition of the signal FE, these peak values m1 and m2 depend on the reflectance of the optical disc. As mentioned in the explanation of the prior art, the reflectance of rewritable optical discs is generally low;
By utilizing the fact that read-only optical discs have a high reflectance, the type of optical disc can be distinguished by checking the magnitude of the peak value of the signal FE. Therefore, when the comparison unit 23 determines that the peak value is lower than the limit value, it is determined that the optical disc has a guide groove, and the selector 20 outputs the signal TE1, and when it is higher than the predetermined value, there is no guide groove. The selector 20 determines this and outputs the signal PTE. In this way, it is possible to select a tracking control means suitable for the optical disc to be played back. The operations of the other components shown in FIG. 2 are the same as those shown in FIG. 1, so their explanations will be omitted.

Note that in this embodiment, the reflectance of the optical disk was detected from the amount of variation in the signal FE caused by defocusing, but the detection of this reflectance was carried out after the focusing control was stabilized. It is also possible to detect the value excluding . That is, in FIG. 2, the peak hold section 22 is eliminated and the signal FE
This is possible by directly sending the signal AS to the focusing control section 8, passing the signal AS through a low-pass filter, and then inputting it to the comparison section 23 for comparison with a predetermined position. Furthermore, if predetermined measures are taken to remove fluctuation components due to track crossing and modulation components due to pits, the individual outputs of each component of the 4-split light receiving element 6 that occur when focusing control is stable can be used. Needless to say, it is possible. (Embodiment 3) A third embodiment of the present invention will be described below with reference to FIG. FIG. 3 is a block diagram of the main parts of the present invention. The configuration of the optical head and the components denoted by the same numbers as those shown in FIG. 1 are the same as in the first embodiment, so a description thereof will be omitted. 3, the difference from FIG. 1 is that the calculation section 18 is abolished, and the comparison section 2
4. Signal TE1 and signal PTE are input to selector 20 and comparison section 24, comparison section 24 compares the amplitudes of TE1 and PTE, and sends an instruction to selector 20 based on the result.

The operation of this embodiment configured as described above will be explained below with reference to FIG. 3. first,
The system controller 21, like the first embodiment,
The focusing control unit 8 is prompted to perform stable focusing control. Next, the system controller 21 controls the tracking control section 10 to forcibly cause the laser spot to cross the track. In this way, the signal TE1 or PTE becomes a sinusoidal tracking error signal having a continuous waveform as shown in FIG. Comparison part 2
4 compares the amplitudes of the two signals TE1 and PTE occurring at this time, and sends an instruction to the selector 20 to output the larger signal. The selector 20 selects the circuit according to this instruction and outputs one of the signals to the tracking control section 10. When the selection of the tracking control means is completed in this way, the system controller 21 stops the forcible control that was being performed on the tracking control section 10, and prompts the execution of tracking control. The operations of the other components are the same as those in the first embodiment, and therefore their explanations will be omitted.

As described above, according to the optical disc device of the embodiment of the present invention, tracking control suitable for the optical disc to be reproduced is performed by directly comparing the tracking error signals used by the respective tracking control means configured in the device. Since you choose the means, you can make a reliable choice.

The series of the present invention can be applied not only to read-only optical disk devices, but also to recording/playback optical disk devices configured with various conventionally known recording methods without any restrictions. can do. For example, since the optical head configuration of this embodiment can be applied as is to a device for a so-called phase-change type optical disk for recording/playback, the structure of the present invention can be added to the conventional technology necessary for a recording/playback device for such an optical disk. It is realized by It is also possible to apply the present invention to an optical disk device for recording and reproducing so-called magneto-optical disks.

[0044]

As is clear from the above embodiments, according to the present invention, by detecting the depth information of the grooves formed in the tracks of the optical disk or by detecting the reflectance of the optical disk, By automatically determining the type of optical disc that is about to be played, selecting the one suitable for the optical disc from among the multiple tracking control means available, and operating with that, stable and stable playback can be achieved regardless of the type of optical disc. It becomes possible to perform accurate tracking control. In addition, the tracking error signal generated by each of the prepared tracking control means is output and evaluated for the optical disc to be played, and the optimal one is selected and operated. It becomes possible to perform stable and accurate tracking control regardless of the type. Therefore, according to the configuration of the present invention, it is possible to realize an optical disc device that is compatible with any type of optical disc. Further, according to the present invention, since such an optical disc device is configured with only one optical head, it is possible to provide a compact and inexpensive optical disc device having such functions.

[Brief explanation of drawings]

FIG. 1 is a block diagram of the main parts of an optical disc device in a first embodiment of the present invention.

FIG. 2 is a block diagram of the main parts of an optical disc device according to a second embodiment of the present invention.

FIG. 3 is a block diagram of the main parts of an optical disc device according to a third embodiment of the present invention.

FIG. 4 is a configuration diagram of the optical system of the optical head in the conventional example and each embodiment of the present invention.

FIG. 5 is a block diagram of the main parts of a conventional optical disc device configured by a first tracking control means.

[Figure 6]
A block diagram of the main parts of a conventional optical disc device configured by a second tracking control means

[Figure 7] Configuration diagram showing changes in shape of received light flux caused by defocusing

FIG. 8 is a graph showing the response of focus error signal FE to defocus amount.

FIG. 9 is a configuration diagram showing the light amount distribution of reflected light on the pupil of the objective lens 2 shown in FIG. 4a, which changes depending on the position of the laser spot with respect to the guide groove of the optical disc.

FIG. 10 is a graph showing the response of the tracking error signal TE1, TE2 or PTE to the amount of track deviation of the laser spot.

FIG. 11 is a configuration diagram showing the difference in the light amount distribution of reflected light on the pupil of the objective lens 2 shown in FIG. 4a, which is caused by the positional relationship between the pit and the laser spot.

[Explanation of symbols]

6 4-split light receiving element 9, 11, 13, 14 Amplifier 10 Tracking control section 15 Subtractor 16 Phase difference detection section 17 Conversion section 18 Arithmetic unit 19, 23, 24 Comparison section 20 Selector 21 System controller 22 Peak hold section

Claims (9)

[Claims] 1. An optical disc comprising: a plurality of different tracking control means that operate by detecting reflected light from grooves formed in a track of the optical disc; and means for selecting one of the plurality of different tracking control means. Device. 2. The optical disc device according to claim 1, wherein the means for selecting one of the plurality of different tracking control means is selected by detecting and evaluating the depth of a groove formed in a track of the optical disc. . 3. A plurality of different tracking control means detect reflected light from the grooves formed in the track using a plurality of photodetectors, and control the plurality of photodetectors according to the positional deviation between the laser spot and the grooves. means for performing tracking based on the amount of phase difference generated in the outputs of at least one pair of photodetectors among the plurality of photodetectors; and an intensity generated in the outputs of at least one pair of photodetectors among the plurality of photodetectors in accordance with the positional deviation. 3. The optical disc apparatus according to claim 1, further comprising means for performing tracking based on the amount of difference. 4. The means for detecting the depth of the groove formed in the track is a means for detecting the amount of light reflected from the groove using at least two photodetectors, and comparing the difference and sum of each detected signal. The optical disc device according to claim 2 or 3. 5. The optical disc device according to claim 1, wherein the means for selecting one of the plurality of different tracking control means detects the reflectance of the optical disc and evaluates the detected reflectance to select the one. . 6. The means for detecting the reflectance of the optical disc includes at least one light source that emits light toward the recording surface of the optical disc, and at least one that detects light from the light source reflected by the recording surface of the optical disc. The optical disc device according to claim 5, comprising two photodetectors. 7. The means for detecting the reflectance of the optical disk is means for detecting a range of variation in output that occurs in at least one of the photodetectors that are constituent elements of the focusing control means during the focus pull-in process of the optical head. The optical disc device according to claim 5. 8. The optical disc device according to claim 5, wherein the means for detecting the reflectance of the optical disc is means for detecting a fluctuation range of a focusing error signal that occurs during a focus pull-in process of the optical head. 9. The means for selecting one of the plurality of different tracking control means includes detecting and evaluating the amplitude of a tracking error signal generated when the laser spot traverses the track for each of the plurality of tracking control means. The optical disc device according to claim 1 or 3, wherein the optical disc device is configured to select.