KR100237333B1 - Optical disk apparatus with the identification circuit for groove/pit region - Google Patents

Abstract

An optical disc having a pit area in which data is recorded along a track by a pit, and a groove area in which grooves are formed along a track for data recording, and an optical disc apparatus for recording / reproducing data therefrom. The optical disc apparatus includes an optical head 104 for projecting a light beam onto the optical disc and a photo detector array 119 for receiving the reflected light. The photodetector array is coupled with a tracking error signal and a preamplifier 107 for generating an RF signal representing the pits. The tracking error signal is used as a clock signal in the flip-flops 204 and 205 and the RF signal is used as an initial setting signal, so that the flip-flop 205 is a signal indicating that the optical head is in the pit area. Create

Description

Optical disc device with groove / pit area judgment circuit

The present invention relates to / from an optical disc having a pit area where recording is made by pits, and a groove area where recording is made by surface physical changes such as Kerr effect changes. An optical disk device for recording / reproducing data.

Groove-formed optical discs are shown in FIG. 7, as known, for example, from US Pat. No. 4,999,825 and the like. As shown in Fig. 7 (a), a known optical disc has a pit area 101A having tracks of pit P in itself, and a car effect change marking for recording EFM-coded data for a compact disc. Tracks in groove G having surface markings in themselves have groove regions 101B formed therein.

It is generally known that a control area for storing control data is provided around the innermost part of the disc. Control data is recorded by the pits protruding and recessed at a certain position on the disc (eg around the innermost portion). On the side, the control area is usually formed in the pit area 101A. Following the control area, a recording area is provided for enabling a user to record data. The recording area is usually formed in the groove area 101B. The control data in the control area includes an address indicating the start point of the recording area, an address indicating the start point of the area in which User Table Of Contents (UTOC) is to be recorded (hereinafter referred to as "UTOC area"), and user data. An address indicating the head of the area, recommended light intensity at the time of recording, and the like.

If the pit width is narrower than half of the track pitch and the groove width is wider than half of the track pitch, as shown in FIG. 7 (b), a tracking error between the pit service 101A and the groove area 101B is shown. The polarity of the signal is reversed.

In the case of the pit area 101A, if the beam spot deviates out of the track from the disc, the tracking error signal TE will be greater than zero to maintain a positive value, and the beam spot will remain in the disc from the track. If it deviates inward, the tracking error signal TE becomes less than zero to maintain a negative value.

In the case of the groove area 101B, however, the tracking error signal TE maintains a negative value less than zero if the beam spot is out of the disc from the track, and the beam spot is inside the disc from the track. If it is out of the tracking error signal (TE) is greater than zero to maintain a positive value.

This inversion on the error signal polarity results in inaccurate servo control. Therefore, in order to solve such a problem, the conventional optical disc apparatus reads the address data and detects which of the two areas (pit area and groove area) is irradiated to the area, for example. Determine the correct tracking error signal polarity. However, this structure on the optical disc device has a problem that the address data cannot be read quickly because two states must be distinguished when the address signal cannot be read immediately.

The first is that the tracking servo is not performed correctly (i.e., reversal of the tracking error signal polarity is required), and the second state is when the disc is gold or defective or soiled with foreign matter (tracking error signal polarity). No reversal). As a result, the optical disk device becomes impossible to operate with high accuracy.

The above-described problem is particularly experienced when the pit area for recording the entire disk control data and the UTOC area are located near the innermost periphery of the optical disc and in the inner peripheral part of the disc adjacent to the pit area, respectively. The optical disc device reads the control data and the UTOC contents for the entire disc at its startup, thereby preparing for operation by the user. The apparatus needs to follow the following procedure to read the UTOC following the control data reading. That is, 1) an optical head is moved around the inside of the disc for recording control data, 2) the control data is read, and 3) an optical head to the groove area according to the UTOC area head address on the control data. 4) invert the polarity of the tracking error signal, 5) read the address by performing servo tracking, and 6) access to the UTOC region. Since the tracking servo is not performed correctly unless the optical head is surely moved to the groove area, the conventional optical disk device is configured to move the optical disk slightly outward from the position specified by the UTOC area head address on the control data. It is designed. As described above, since the optical head moving distances on the steps 3 and 6 in the conventional apparatus cannot be shortened, it took a long time to start the apparatus.

It is therefore an object of the present invention to provide an optical disc apparatus capable of reliably determining the pit area and groove area of an optical disc prior to operating the tracking servo.

To achieve the above object, there is provided an optical disc apparatus for recording / reproducing data to / from an optical head having a pit area in which data is recorded along a track by a pit, and a groove area in which grooves are formed along a track for recording data. The optical disk apparatus includes: optical head means for projecting a light beam onto the optical disk and generating an electrical signal based on the reflected light therefrom; First generating means for generating an RF signal indicative of the pits based on the electrical signal; Second generating means for generating a tracking error signal which is a wave signal representing a track traverse based on the electrical signal; Clock generation means for generating a clock signal using the wave signal; Detection means for detecting the RF signal and generating an RF detection signal indicative of the presence of the RF signal; And an area detecting means for receiving the clock signal and the RF signal and generating a pit area detecting signal when the optical head means traverses a predetermined number of tracks.

According to the optical disk apparatus of the present invention, even when a light beam traverses the tracks, it is possible to stably discriminate or determine between the pit area and the groove area. When recording or reproducing an optical disc having a pit area and a groove area in the optical disc apparatus, the optimum tracking servo for the area is achieved due to the stable separation between the pit area and the groove area. Moreover, access to the vicinity of the boundary between the two regions can be made stable at high speed.

1 is a block diagram of an optical disk apparatus according to a first embodiment of the present invention.

FIG. 2 is a detailed block diagram of the preamplifier and pit area detection circuit shown in FIG.

The third (a), third (b), third (c), third (d), third (e), third (f) and third (g) degrees are Waveform observation at each point on the first and second degrees.

4 is a flowchart showing steps performed by the system control shown in FIG.

5 is a block diagram of an optical disk device according to a second embodiment of the present invention.

FIG. 6 is a flowchart showing the steps performed by system control on the FIG.

7 (a), 7 (b) and 7 (c) are diagrams showing an arrangement structure of a pit area and a groove area.

* Explanation of symbols for main parts of the drawings

101A: Pit Area 101B: Groove Area

103: motor drive circuit 117: tracking actuator

118 lens 119 photodetector array

The above objects and other features of the present invention will be clearly understood through the following description of the preferred embodiments with reference to the accompanying drawings, the same parts are given the same reference numerals throughout the drawings.

Hereinafter, with reference to FIGS. 1 to 4, the operation at the start of the optical disk device according to the first embodiment of the present invention will be described.

1 is a block diagram of an optical disk device according to the first embodiment. As shown in Fig. 7A, the optical disc 101 has a pit area 101A and a groove area 101B. The UTOC area | region is arrange | positioned around the innermost part peripheral part of the groove area | region 101B. The spindle motor 102, which is driven and rotated by the motor driving circuit 103, rotates the optical disc 101. The optical head 104 includes a lens 118 for collecting the light beams, a tray actuator 117 for radially moving the lens within the optical head range for fine adjustment, and the reflected light from the optical disk as an electrical signal. A photodetector array 119 for converting is provided. The optical head 104 is moved in the radial direction by a traversing mechanism 105 driven through the traversing drive circuit 106. The preamplifier 107 generates and outputs a tracking error signal TE (C) or RF signal A by adding or subtracting the electrical signal output from the photodetector array 119 in the optical head 104.

According to FIG. 2, the photodetector array 119 and the preamplifier 107 are shown in detail. Photodetector array 119 has eight photodetector elements P1, P2, P3, P4, P5, P6, P7 and P8. Elements P1 and P2 are provided before and after the tracking direction, respectively, and elements P3 and P4 are provided on both the left and right sides of the tracking direction, respectively. The other elements P5, P6, P7 and P8 are provided in the center part. The preamplifier 107 has an adder 107a and a subtractor 107b. Three beams are reflected from the disk and enter the photodetector array 119. The adder 107a adds the signals from the elements P3 and P4, thereby generating the same sum signal P3 + P4 as the RF signal A. The subtractor 107b subtracts the signal from the element P2 from the signal from the element P1 to generate the same difference signals P1 to P2 as the tracking error signal C.

According to FIG. 1, the tracking error signal is inverted by the TE inversion circuit 108, i.e., -1. The TE switching circuit 109 is switched between the solid line position for receiving the inverted tracking error signal and the dotted line position for receiving the non-inverted tracking error signal, and the signal is input to the TR loop filter 110. The signal input to the TR loop filter is subject to phase compensation, as described below.

When the signal input to the TR loop filter 110 is a positive signal (+ signal), the filter 110 generates a positive operation signal to the tracking actuator 117 to thereby light the lens 118. Move towards the inside of the disk within the head range.

On the other hand, if the signal input to the TR loop filter 110 is a negative signal (-signal), the loop filter 110 generates a negative operating signal to the actuator 117, thereby causing the lens 118 to receive the optical signal. Move towards the outside of the disk within the head range. The degree of movement is proportional to the amplitude of the actuation signal, that is to say the amplitude of the tracking error signal.

When the optical head 104 is in the pit area 101A, the switching circuit 109 is moved to the dotted line position, and when the optical head 104 is in the groove area 101B, the switching circuit 109 is Move to the solid line position. This will be described later.

In the case of the pit area 101A, the switching circuit 109 is aligned with the dotted line position. As shown in Fig. 7 (b), when the optical head 104 is further deviated toward the outside of the disc (outside off-track state), the tracking error signal is from the zero level. Change to the plus level. Since the switching circuit 109 is in the dashed position, the TR loop filter 110 sends a positive actuation signal to the tracking actuator 117, thereby bringing the lens 118 into the optical head 104 range. Move toward the inside of the disk. In other words, the optical head 104 returns to the center portion (on-track state) of the track. As the optical head 104 further exits and is in an off-track state, the tracking error signal changes from zero level to minus level. That is, the TR loop filter 110 sends a negative operation signal to the tracking actuator 117 to move the lens 118 out of the disk within the optical head 104 range. That is, the optical head 104 returns to the on-track state.

On the other hand, in the groove area 101B, the switching circuit 109 is moved to the solid line position. As shown in FIG. 7 (b), when the optical head 104 comes out and enters the outer off-track state, the tracking error signal changes from zero level to minus level, but the half It is changed to a positive level by electricity 108. Accordingly, the TR loop filter 110 sends the positive actuation signal to the tracking actuator 117, thereby moving the lens 118 into the disc within the optical head 104 range. That is, the optical head 104 is returned to the on-track state. When the optical head 104 is pulled out and within the inner off-track state, the tracking error signal changes from zero level to positive level, but by the inverter 108 to negative level. Thus, the TR loop filter 110 sends a negative actuation signal to the tracking actuator 117 to move the lens 118 out of the disc within the optical head 104 range. That is, the optical head 104 returns to the on-track state.

The switching circuit 109 is switched by system control 112 which determines whether the optical head 104 is in the pit area 101A or in the groove area 101B.

The switch 116 is connected to the output side of the TR loop filter 110. When the switch 116 is switched to the solid line position, the output side of the TR loop filter 110 is connected to the tracking actuator 117. When the switch 116 is switched to the dashed position, the connection between the TR loop filter 110 and the tracking actuator 117 is broken and the input to the tracking actuator 117 is grounded. The switch 116 is turned to the solid line when the optical head 104 follows the track (i.e., playback or recording mode), but moves to the dotted line when the optical head 104 traverses the track (i.e. search mode). You lose.

The tracking error signal C and the RF signal A are input to the pit area detection circuit 111 that generates the pit search signal F. The system control 112 receives the pit detection signal F and also controls the TE switching circuit 109, the switch 116, the transverse drive circuit 106 and the spindle drive circuit 103.

2 shows details of the pit area detection circuit 111 including the RF detection circuit 201, the comparator 202, the divider 203, and the flip-flops 204 and 205. The pit area detection circuit 111 is influenced by the crossing drive circuit 106 or the forced crossing drive circuit 501 which will be described later with reference to FIGS. 5 and 6 without the optical head following the track. It works when receiving and crossing the track.

The RF detection circuit 201 has a high pass filter 201a, an envelope detector 201b, and a comparator 201c. The high pass filter 201a receives the RF signal A (FIG. 3 (a)) to block low frequency components. During the traversal of the optical head 104, if the optical head 104 is in the pit region 101A, a high frequency signal is generated which gradually changes along a sinusoidal curve, but the optical head 104 Is in the groove region 101b, a low frequency sinusoid is generated.

In other words, when the tracking servo is not performed, the relative position between the track and the light beam is not fixed, for example, at the time of approach or at the same time, so that the amplitude of the RF signal is as shown in FIG. 3 (a). Change. The RF signal includes a high frequency component in the pit region 101A because the pit shows a large amplitude in the on-track portion and a small amplitude in the off-track portion. On the other hand, since there is no pit in the groove area 101B and thus does not include the RF signal high frequency component, the elevation is changed every time one track is traversed.

The high pass filter 201a blocks low frequency components, and the envelope detector 201b detects an envelope curve of the high frequency signal. Subsequently, the comparator 201c compares the envelope curve with a predetermined threshold value to generate a pulse in the pit area and does not generate a pulse in the groove area as shown in FIG. 3 (b). The signal shown in FIG. 3 (b) is called an RF detection signal. The RF detection signal indicates a high level signal in the pit area 101A when the optical head 104 traverses on the track. Comparator 202 receives the tracking error signal as shown in FIG. 3 (c). Here, because the optical head 104 is traversing the track, the tracking error signal is in a sinusoidal curve. The comparator 202 compares the tracking error signal with a predetermined threshold to generate a pulse (Fig. 3 (d)) corresponding to each track. The threshold may have hysteresis to prevent chattering. The signal shown in FIG. 3 (d) is called a track cross signal. The divider 203 divides the frequency of the track cross signal into half frequencies.

Flip-flop 204 has a set terminal for receiving the RF detection signal. When the signal at the set terminal is at the high level, the Q output of the flip-flop 204 always generates a high level signal even when a clock signal is input to the clock terminal CK. If the signal at the set terminal is a low level signal, the Q output maintains the signal being generated, but is a high level signal in this case in response to each step-up leading edge of the clock signal. The signal is applied to the data input D. The clock signal is the output of the divider 203. That is, as shown in FIG. 3 (f), the Q output of the flip-flop 204 generates a high level signal while the optical head 104 is in the pit area, but the clock signal in the groove area [third (e) changes to a low level signal in response to the first step-up tip of FIG.

The flip-flop 205 has a data input D for receiving the Q output of the flip-flop 204 and a clock input CK for receiving the output from the divider 203. The Q output changes to the data input side signal in response to the step-up tip of the clock signal. That is, as shown in FIG. 3 (g), the Q output of the flip-flop 205 also generates a high level signal while the Q output of the flip-flop 204 generates a high level signal, It changes to a low level signal in response to the second step-up tip of the clock signal (Fig. 3 (e)).

The optical head 104 is generally called an optical head means; The comparator 202 and the divider 203 are called clock generating means for generating a clock signal for the track to be traversed; The preamplifier 107 is called RF signal generating means; The RF detecting circuit 201 is called RF detecting means; In addition, a circuit including the D flip-flops 204 and 205 is called a pit area detecting unit.

4 is a flowchart showing the staff executed by the system control 112 of the first embodiment.

In operation, the switch 109 is first moved to the dashed position, and the switch 116 is also moved to the dashed position (step 400). Subsequently, the spindle drive circuit 103 rotates the optical disc 101, and at the same time, the optical head 104 is moved toward the inner circumference of the optical disc by the transverse drive circuit 106 (step 401). It is moved until the detection switch 115 is turned on (step 402). The detection switch is pre-adjusted to turn on when the optical head reaches the readable position by the control data. Subsequently, the switch 116 is moved to the solid line position (403a) to prepare for tracking control.

The spindle drive circuit 103 drives the spindle motor 102, whereby the optical disc 101 rotates at a constant rotational speed, and the system control 112 starts a focus / tracking servo to initiate the pit area 101A. Read the control data (step 403b). After reading the control data, the system control 112 releases the tracking servo by moving the switch 116 to the dotted line position (step 403c). Subsequently, when the optical head 104 is moved (step 404) by the transverse driving circuit 106 toward the outer periphery, when the pit detection signal of FIG. 3 (g) changes to a low level signal (step 405). Will be moved to).

As described above, the pit detection signal is a high level signal in the pit area 101A, and changes to a low level signal when the optical head 104 enters the groove area 101B. Therefore, if the optical head 104 is stopped in response to the pit detection signal change from the high level signal to the low level signal, then the optical head 104 at that time is near the boundary between the pit area 101A and the groove area 101B. That is, it may be located near the UTOC region. When the optical head 104 is regular, the switch 109 is changed to the solid line position (step 406) to reverse the polarity of the tracking error signal, and the switch 116 is also changed to the solid line position to operate the tracking servo. It starts. UTOC is also changed to the solid line position to start the tracking servo. The UTOC area is then accessed to read UTOC data (step 407).

According to the present invention, the optical head 104 does not have to be moved long distance to the outer circumference side to access the UTOC region. Thus, access to the UTOC region can be made within a short time. That is, as the time required for initial set up can be shortened, the user does not have to wait long before using the disk.

Further, even if the tracking servo is inefficient, the pit detection signal can be stably secured, so that the operation of the optical disc apparatus is stabilized. Further, except for the frequency divider 203, a pit detection signal can be secured for each track. In this case, there is no need to consider the two-track transverse distance of the optical head in approaching the UTOC region. That is, as the initial setting time is significantly shortened, high speed operation of the optical disc device is possible.

Let us look at the transversal velocity of the light beam in track traversal for the purpose of detecting the pit area. As described above, the pit area detection circuit 111 calculates a track crossing number using the track cross signal so that the pit area can be detected. The track cross signal is a binary signal of the tracking error signal, and when the crossing speed decreases and chattering occurs in the comparator, a burr type at the comparator output near the zero crossing point is sometimes used. It is accompanied by a burr-like noise signal. For example, if, as in the first embodiment, the pit detection signal is taken while the optical head 104 is moved radially by the traversing mechanism 115, there is no problem, but the optical head is in the middle of the disc. This may be a problem when stopping and when it is necessary to determine between the pit area and the groove area. 5 is a block diagram of an optical disk device designed to solve this problem.

A second embodiment will be described with reference to FIGS. 5 and 6.

Compared with the embodiment of FIG. 1, the embodiment shown in FIG. 5 differs in this respect. A forced TR driving circuit 501 formed of a constant voltage source such as generating + Vc or -Vc is provided. Three positions, i.e., the solid line positions for connection with the TR loop filter 110; The dotted line position for connection with ground; And a switch 502 for selectively turning on one dashed line position for connection with the forced TR driving circuit 501. The output of the switch 502 is connected to the tracking actuator 117.

When the switch 502 is in the dashed-dotted position, a constant voltage (+ Vc) is applied to the tracking actuator 117 to move the lens 118 toward the inside of the disc at a speed determined by the constant voltage (+ Vc). Is applied. That is, the light beam forcibly traverses the track to perform area detection by the pit area detector 111. When the forced TR driving circuit 501 maintains a constant voltage (-Vc) instead of + Vc, the tracking actuator 117 moves the lens 118 out of the disk and can achieve the same result.

System control 503 controls the transverse drive circuit 106, the TE switching circuit 119 and the TR drive signal switching circuit 502.

6 is a flowchart showing the operation of the optical disc apparatus according to the second embodiment.

The objective lens in the optical head 104 is generally called light concentrating means; The tracking actuator in the optical head is called the tracking actuator; The forced TR drive circuit 501 is called forced TR drive means; System control 503 is also called control means.

Prior to obtaining the pit detection signal, system control 503 moves the switching circuit 502 to a dashed line position (step 601) to couple the forced TR drive circuit 501 to the tracking actuator 117. A forced drive signal such as + Vc output from the forced TR drive circuit 501 is applied to the tracking actuator in the optical head 104, whereby the objective lens is relatively fast along the radial direction (e.g., a crossing frequency of 5 kHz). Will move. The pit area detector 111 then generates the pit detection signal while the objective lens is moving (step 602). The switch 502 then returns to the solid line position to connect the TR loop filter 110 with the tracking actuator 117.

In the method as described above, when the pit detection signal is obtained, the objective lens is forcibly moved in the radial direction so that the pit area is detected under the influence of the noise removed near the zero crossing point of the track cross signal.

The forced drive signal generated from the forced TR drive circuit 501 is preferably a sinusoidal signal having a first resonance frequency or a low frequency of the tracking actuator, instead of ± Vc. When the signal of the frequency is applied, vibration of the lens due to the influence of the forced driving signal can be prevented. The subsequent operation is quick and stable. Needless to say, depending on the choice, a pulse type voltage may be applied.

In the first embodiment, the pit area is detected for each of the two traversed tracks, while the division ratio of the divider 203 is preferably set in accordance with the calculated eccentricity. For example, in the case where the 1.6 탆 track pitch has an eccentricity of 100 탆, the split ratio is set not to be smaller than 63 (100 / 1.6 = 62.5). This prevents the light beam from moving from the groove area 101B to the pit area 101A due to the eccentricity after reading the pit detection signal before completion of the tracking servo.

The track cross signal is used in detecting the track crossing number in the first and second embodiments, but any signal representing the track crossing number by the light beam is obtained by binarizing an envelope signal or the like which is an RF signal. Can be.

Further, in the first and second embodiments, the pit area 101A is detected for each of the two tracks detected, but the pit area may be detected for any track traversal number. In addition, the number may not be the number of steps, and may be changed according to the RF detection signal or the track cross signal. For example, while the optical head 104 moves radially in the pit area 101A, the RF detection signal and the track cross signal are observed to detect the number of times the RF detection signal changes as the track is traversed. do. Then, the number of tracks to be traversed for area detection is determined based on the detected number of times. In the case of the number of tracks to be traversed for the area detection, the traversing speed can be reduced at a high speed, while the amplitude of the RF signal can be increased by lowering the amplitude.

According to the first and second embodiments, by eliminating the envelope circuit 201b, the RF detection signal can be detected from a high frequency component extracted from the RF signal, or another method can be used.

According to the structure in the first and second embodiments above, high level signals are generated when the pits are detected. Of course, a structure in which low level signals are generated upon pit detection is also possible.

The optical discs in the first and second embodiments each have a pit area and a groove area in the inner peripheral part and the outer peripheral part thereof. The same effect can be obtained even in the case of an optical disc having a pit area and a groove area in the outer peripheral part and the inner peripheral part, or having a plurality of pit areas and groove areas.

In the first embodiment, an example of the pit area detection circuit has been described. The structure may be variously changed as long as the circuit is configured to detect the presence / absence of high frequency components in the RF signal according to the number of tracks traversed by the light beam. For example, the RF detection signal may be latched at the step-up end of the track cross signal. If the latching result is high, the pit detection circuit is moved to a high level. Alternatively, the RF signal is latched a predetermined number of times through the track cross signal, and if the latching result is high, the pit area is detected according to the number of times.

In the second embodiment, after obtaining the pit detection signal, the switch 502 is switched to the TR loop filter 101. The effect of the present invention even if the switch 502 allows the user to select a different state, for example, a state without a drive signal or a state of the same flow, even when the pit detection signal is taken internally and then changed to another state. Get the same effect as

As described above, when the optical disc has both the pit area and the groove area, if the pit area and the groove area are detected according to the present invention, a stable tracking servo is ensured. Moreover, in the optical disk device according to the present invention, access to the UTOC area is made at high speed.

Although the present invention has been described in detail in connection with preferred embodiments with reference to the accompanying drawings, it should be noted that various changes and modifications by those skilled in the art are naturally possible. It is to be understood that such changes and modifications also fall within the scope of the present invention without departing from the scope of the invention as defined by the claims.

As described above, according to the optical disk device of the present invention, the high speed access to the stable tracking servo and the UTOC area is ensured, thereby greatly improving the quality and work efficiency of the disk-related data recording and reproducing operation.

Claims (7)

An optical disc apparatus for recording / reproducing data to / from an optical disc having a pit area in which data is recorded along a track by a pit, and a groove area in which grooves are formed along the track for data recording, comprising: Optical head means (104) for projecting to generate an electrical signal by reflected light from the optical disc; First generating means (107a) for generating an RF signal representing the pit based on the electrical signal; Second generating means (107b) for generating a wave signal indicating a crossing of the track on the basis of the electric signal; Clock generation means (202, 203) for generating a clock signal using the wave signal; Detection means (201) for detecting the RF signal to generate an RF detection signal indicative of the presence of an RF signal; And an area detecting means (202, 203) for receiving the clock signal and the RF signal and generating a pit area detecting signal when the optical head means (104) traverses a predetermined number of tracks. . 2. An optical disc apparatus according to claim 1, wherein said optical head means comprises a tracking actuator (117) for radially moving the light beam source. The apparatus of claim 2, further comprising: tracking error generating means for generating a tracking error signal based on the electrical signal; And a loop filter for receiving the tracking error signal, generating an actuation signal to actuate the tracking actuator to cause the light beam to stay on the track. 4. The optical disc apparatus according to claim 3, wherein the pit area detection signal is used to change the polarity of the tracking error signal between a tracking error signal in the pit area and a tracking error signal in the groove area. 4. An optical disc apparatus according to claim 3, further comprising blocking means (116) for blocking the tracking actuator (117) from the loop filter (110) when the light beam crosses the track. 3. An optical disc apparatus according to claim 2, further comprising forced tracking drive means (501) for generating a forced signal to said tracking actuator (117) to force said light beam to cross the track. The optical disc apparatus according to claim 1, wherein the predetermined number of tracks is larger than the number of tracks covered by the amount of eccentricity of the optical disc.