KR20050038644A - Track jump unit - Google Patents

Abstract

The invention relates to a track jump unit and a method for performing jumps of a light beam (221) of an optical pickup device (201) from a first track to a second track of a disc. The radial error signal is detected, and an extended radial error signal (EXE) is derived from the radial error signal, this extended radial error signal being a monotonous signal comprising portions having track identifiers associated therewith. Based on the value of the current track identifier (ID) and the extended radial error signal, a displacing signal is generated in order to displace the light beam. To perform a jump, the current identifier is modified, so as to displace the light beam to the desired track.

Description

Track Jump Unit {TRACK JUMP UNIT}

The present invention relates to a track jump unit for jumping a light beam of an optical pickup device from a predetermined track of a disc to another track.

The invention also relates to a method of performing a jump of a light beam of an optical pickup apparatus from a predetermined track of a disc to another track.

In particular, the present invention relates to an optical disc apparatus, for example a CD or DVD player and / or recorder, which reads data from and / or writes data to the optical disc.

A conventional optical disc apparatus for reading data written on a disc and / or writing data on an optical disc is illustrated in FIG.

1 is a block diagram showing the overall structure of an optical disk apparatus. The optical disk apparatus includes an optical pickup apparatus 101 capable of transmitting the light beam 102 to the disk 100 and receiving the light beam 102 from the disk 100. The optical disk apparatus further includes an actuator 103 capable of displacing the optical pickup apparatus 101 when the displacement signal DS is provided. Processor 104 processes the light beam reflected from the disc to read data from the disc, or controls the light beam transmitted to the disc to write data on the disc.

The disc 100 includes a track in which data to be read is recorded. When data is read from the disc, the light beam 102 must stay in the middle of a given track. If the processor 104 detects that the light beam 102 is not in the middle of a predetermined track, a displacement that displaces the optical pickup device 101 to keep the light beam 102 in the middle of the predetermined track. The signal DS is transmitted to the actuator 103. This operation is called "tracking". Based on the light beam reflected from the disk, the tracking control loop can keep the light beam 102 in the middle of a given track.

Further, the actuator 103 can be used to perform a small jump from a given track to another track located some track away from the given track. This operation is called "jumping". The jump control loop is used to provide a displacement signal DS for displacing the actuator 103 so that the light beam is displaced from a predetermined track to a desired track. When the jump operation is performed, first, the actuator 103 is moved through the track at a predefined speed. Based on the reflected light beam, the counter counts the number of tracks through which the light beam has passed. By monitoring the number of tracks passed over a fixed time interval, a speed measurement is achieved. Thus, since the number of tracks passed per second is known, the actuator moves for the correct amount of time to reach the desired track.

However, this jump operation can be performed as long as accurate speed measurement is possible. As a result, since accurate speed measurement is possible only after several tracks, this jump operation cannot be performed to jump a small number of tracks. Therefore, if one wants to perform a jump of a small number of tracks, for example five tracks, this jump operation makes the arrangement of the light beams incorrect.

In addition, since two different control loops are used for tracking and jumping, a transient phenomena may appear when switching from the tracking operation to the jump operation. During these transients, the light beam may move in the wrong direction. This causes the light beam to be placed incorrectly and requires a long time to perform the jump.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

1 shows an overall structure of an optical disk apparatus according to the background art,

2 is a block diagram illustrating a track jump unit according to the present invention;

FIG. 3 illustrates a disk structure and a light beam used for detecting a radial error signal by the track jump unit of FIG. 2.

4 illustrates a signal detected by the track jump unit of FIG.

FIG. 5 illustrates an extended radial error signal derived from the radial error signal of FIG. 4.

6 illustrates a track identifier,

7 illustrates a jump of one track performed in accordance with the present invention,

8 illustrates a jump of several tracks performed in accordance with a preferred embodiment of the present invention.

SUMMARY OF THE INVENTION An object of the present invention is to provide a track jump unit capable of accurately performing a jump of several tracks by eliminating the above problem.

According to the present invention, there is provided a track jump unit for jumping a light beam of an optical pickup device from a first track of a disc to a second track, wherein the track jump unit includes:

Displacement means controlled by a displacement signal to displace the light beam;

Reflected light beam detection means for detecting a light beam reflected from the disk and generating a reflected light beam signal when the light beam from the optical pickup device is supplied to the disk;

Radiant error detection means for generating a radial error signal including at least a portion corresponding to the first track when at least one reflected light beam signal is supplied;

Counting means for associating at least one current track identifier with the first track;

An extended radial error calculating means for calculating an extended radial error signal, when the radial error signal is supplied, the expanded signal being a monotonic signal based on at least a portion of the radial error signal, the extended error signal comprising a portion having a track identifier associated therewith;

Generating means for generating the displacement signal, controlled by the extended radial error signal and the current track identifier, so that a jump from the first track to the second track is performed by modifying the current track identifier. .

According to the present invention, the displacement signal for controlling the displacement means is generated based on the extended radial error signal and the track identifier. Since the extended radial error signal is derived from the reflected light beam, it can be calculated during tracking. Therefore, only one control loop can be used for tracking and jumping. This eliminates the transient.

In addition, since the jump is performed by modifying the track identifier, no speed measurement is required. Thus, such a track jump unit can be used to perform a small jump, for example a jump from one track directly to an adjacent track.

In a preferred embodiment, a jump from a given track to a desired track is performed by jumping from one track directly to the adjacent track until the desired track is reached, and by jumping from the track under consideration by modifying the current track identifier. Is performed.

According to this preferred embodiment, only a small number of identifiers are needed.

The present invention also relates to a method of performing a jump performed by a track jump unit as described above.

The invention also relates to a computer program comprising a set of instructions which, when loaded into a processor or computer, cause the processor or computer to perform the method.

These and other aspects of the invention will be apparent from the embodiments described hereinafter and become apparent when reference is made to the embodiments described below.

The track jump unit according to the invention is shown in FIG. 2. The track jump unit includes an optical pickup device 201, a displacement means 202, a reflected light beam detection means 203, a radial error detection means 204, a counting means 205, and an extended radial error calculation means 206. ) And a generating means (207).

The light beam 221 is transmitted to the disc 211. Then, the reflected light beam is detected by the reflected light beam detecting means 203, and the reflected light beam detecting means 203 generates the reflected light beam signal 231. The reflected light beam signal 231 is transmitted to the radial error detecting means 204, and the radial error detecting means 204 receives the radial error signal 232, as described in more detail in Figs. Create If the light beam 221 is on a given track, the counting means 205 associates the current track identifier 234 with the given track.

The extended radial error calculating means 206 calculates the extended radial error signal 233 based on the radial error signal 232 as described in more detail with reference to FIG. 5. The extended radial error signal 233 includes a portion having a track identifier associated therewith, as described in more detail in FIG. 6. The extended radial error signal 233 and the current track identifier 234 are transmitted to the generating means 207, which generates the light beam 221 as described in more detail in FIG. Generates a displacement signal 235 for controlling the position of.

3a to 3c show disk structures and signals used to detect radial error signals. The disc includes a track on which data is recorded. For example, a track on a DVD can have a picture of a video, and a DVD can have 45000 tracks. The track comprises pits and lands, the pit being represented by a rectangle in FIG. 3, where three tracks T1 to T3 are represented.

When the light beam is incident on the pit, the reflected light beam signal is low, whereas when the light beam is incident on the land, the reflected light beam signal is high. The attributes are used to record digital data on the disc and read these data from the disc, as described later. When a light beam, for example the main light beam S of FIG. 3 is incident on a track, for example T2, and the disk is rotating, the main light beam S is a pit, then a land, then a pit. Incident on the back. Therefore, the reflected light beam signal that can be detected by the photodiode is varied. These variations are used to detect "1" and "0" recorded on the disc. For example, "1" may be detected when there is a shift between the pit and the land.

The attributes of the pit and land are also used to detect radial error signals that can be used for tracking operations. To detect the radial error signal, two secondary light beams S1 and S2 are used, which are arranged symmetrically with respect to the primary light beam S.

In FIG. 3B, the main light beam S is incident on track T2. Therefore, the secondary light beams S1 and S2 are off-track, and the reflected light beam signals corresponding to S1 and S2 are equally high. The radial error signal is detected by calculating the difference between the reflected light beam signals corresponding to S1 and S2, whereby the difference is zero when the main light beam is on-track.

In FIG. 3A, the main light beam S is almost off-track to the left of track T2, the first secondary light beam S1 is almost on-track, and the second secondary signal S2 is off-track. Therefore, the radial error signal is negative.

In FIG. 3C, the main light beam S is almost off-track to the right of track T2, the first secondary light beam S1 is off-track, and the second secondary signal S2 is almost on-track. Therefore, the radial error signal is a positive value.

During tracking, in order to displace the main light beam S, a radial error signal is used to transmit a displacement signal to the displacement means. If the radial error signal is zero, the main light beam S is on track, and no displacement signal is transmitted to the displacement means. If the radial error signal is negative, a displacement signal is generated to move the main light beam to the right until the radial error signal becomes zero. If the radial error signal is a positive value, a displacement signal is generated to move the main light beam to the left until the radial error signal becomes zero. The displacement means may be, for example, the actuator 103 of FIG. 1.

4 shows a disk cross section and a signal detected by the track jump unit according to the invention. From top to bottom, the disk cross section, the center opening signal CA, the radial error signal RE, the radial polarity signal RP and the track loss signal TL are shown.

The center aperture signal CA is an alternative part of the reflected light beam signal corresponding to the main light beam S of FIG. 3. If the main light beam is on-track, for example at track T1, T2 or T3, the center aperture signal CA is minimal since the track comprises a pit. If the main light beam is off-track, the center aperture signal CA is maximum since only the off-track portion of the disc contains lands. The transition between off-track and on-track is characterized by the fact that the central aperture signal passes through zero.

The radial error signal RE is maximum when the main light beam S is transitioning between the off-track portion and the track, zero when the main light beam S is in the middle of the track, and the main light beam S is It is minimal when there is a transition between the track and the off-track portion, and zero when the main light beam S is in the middle of the off-track portion.

The radial polarity signal RP is obtained by digitizing the radial error signal RE, and the track loss signal TL is obtained by digitizing the center opening signal CA.

5 illustrates how the extended radial error signal ERE is derived from the radial error signal RE. In this example, the track under consideration is track T2, in other words, the main light beam S is incident on track T2.

The portion of the radial error signal RE corresponding to track T2 is considered as the basis for the extended radial error signal ERE. Therefore, the portion of the radial error signal RE corresponding to the off-track portion between the tracks T2 and T3 is inverted, and the offset corresponding to the amplitude of the inverted portion is added to the extended radial error signal ERE. Then, the offset corresponding to the amplitude of the radial error signal RE portion corresponding to track T3 is added to the extended radial error signal ERE. On the other side of the track T2, the portion of the radial error signal RE corresponding to the off-track portion between the tracks T2 and T1 is inverted, and an offset corresponding to the amplitude of the inverted portion is added to the extended radial error signal ERE. . Then, the offset corresponding to the amplitude of the radial error signal RE portion corresponding to the track T1 is added to the extended radial error signal ERE. In this way, a monotonic signal including different portions of the radial error signal RE is obtained, and inversion and / or shift are possible.

That is, the portion of the radial error signal RE inverted and shifted to obtain the extended radial error signal ERE is the portion of the radial error signal RE corresponding to the off-track portion of the disc. This off-track portion of the disc can be easily detected when the track loss signal TL is high. The portion of the radial error signal RE which is shifted only to obtain the extended radial error signal ERE is the portion of the signal corresponding to the on-track portion. These on-track portions correspond to the track loss signal TL in the low state.

It is important to note that not all radial error signals RE are available. In fact, the radial error signal RE can only be detected for the track under consideration, i.e., track T2 in the above example. In this case, the extended radial error signal ERE may be calculated as follows.

The portion of the radial error signal RE corresponding to track T2 is considered as the basis for the extended radial error signal ERE. The offset corresponding to this portion is then added to the extended radial error signal ERE, either on the extended radial error signal ERE or the like. In other words, the extended radial error signal ERE is a forged signal including a portion having an amplitude equal to the amplitude of the radial error signal RE portion corresponding to the track under consideration.

Advantages of using the extended radial error signal ERE are as follows. If the radial error RE has a value x, the tracking control loop has no way of knowing whether the main light beam S is at point A or at point B. Therefore, there is no reliability in tracking. For example, suppose there is an unwanted jump of the light beam from the middle of track T2 to point A. When the radial error signal RE is used as an input to the tracking control loop, this loop will take the primary light beam until the primary light beam is at point B and the radial error signal RE has a value of zero. Respond to generate a signal to displace to the left. Thus, the main light beam is in the middle of track T1, instead of in the middle of track T2.

However, if the extended radial error signal ERE is used as an input of the tracking control loop, the value of the extended radial error signal ERE differs depending on whether the main light beam is at point A or point B. Suppose there is an unwanted jump of the light beam from the middle of track T2 to point A. Accordingly, the extended radial error signal ERE has a positive value y, and the tracking control loop moves the main light beam to the right until the extended radial error signal ERE has a value of zero. Generate a signal to displace. When there is a shift of the main light beam from the middle of the track T2 to the point B, the extended radial error signal ERE has a negative value z, and the tracking control loop indicates that the extended radial error signal ERE is Until it has a value of zero, a signal is generated for displacing the main light beam to the left.

6 illustrates how a track identifier is associated with the extended radial error signal ERE. In this example, the track to be considered is the track T2, in other words, the main light beam S is incident on the track T2. The current track identifier is associated with track T2. In this example, this identifier is equal to zero. Thus, when the light beam is displaced radially right, the identifier is incremented each time the track loss signal TL indicates a transition from high to low or vice versa. If the light beam is displaced radially left, each time the track loss signal TL exhibits such a transition, the identifier is reduced. Therefore, the identifier associated with track T2 is zero, the identifier associated with track T1, or the portion of the extended radial error signal ERE corresponding to track T1, is -2, and the identifier associated with track T3 is two.

When only a portion of the radial error signal RE corresponding to the track under consideration is detected, the track identifier can be determined as follows. In order to calculate the extended radial error signal ERE, if an offset is added to either side of the radial error signal RE corresponding to the track under consideration, the identifier is increased. If an offset is added to the other side of the radial error signal RE corresponding to the track under consideration, the identifier is increased.

7 illustrates how a jump is performed in accordance with the present invention. The current track identifier and the extended radial error signal ERE are transmitted to the generating means. The current track identifier indicates which part of the extended radial error signal ERE is to be used by the generating means. For example, if the current track identifier is equal to zero, the portion of the extended radial error signal ERE to be used for tracking by the generating means is the portion that passes the value zero.

Suppose a light beam is incident on track T2 and you want to perform a jump from track T2 to track T3. This jump is performed by modifying the value of the current identifier sent to the generating means. In fact, suppose that instead of the identifier zero, the value -2 is sent to the generating means. Therefore, the part to be used by the generating means is a part passing the value x1, that is, a part corresponding to the track T1. Therefore, the value of the extended radial error signal ERE becomes x1. In this way, the generating means generates a signal for displacing the light beam to the right until the extended radial error signal ERE has a value of zero, thereby bringing the current identifier back to zero. However, since the light beam is actually in the middle M2 of the track T2 and not in the middle M1 of the track T1, this displacement causes the light beam to come in the middle M3 of the track T3. Therefore, a jump from track T2 to track T3 is performed.

When a jump from track T2 to track T1 is performed, instead of the current identifier 0, identifier 2 is transmitted to the generating means.

An example of a jump from one track to an immediately adjacent track will be described. It is important to note that longer jumps may be performed in accordance with the present invention. For example, if a jump from track T2 to the track located two tracks apart from track T2 to the right of track T2 should be performed, instead of the current identifier 0, identifier -4 is transmitted to the generating means.

8 illustrates a jump according to a preferred embodiment of the present invention.

In step 801, a jump is started from the current track to a track located to the right by N tracks in the current track, where N is an integer, for example N = 10. In step 802, the identifier sent to the generating means is modified and the value -2 is sent to this generating means. As illustrated in FIG. 7, this leads to a jump from the current track to the track located immediately adjacent to the right, which causes the identifier to become zero again. In step 803 the counter is incremented in parallel. If a one-track jump was performed, i.e., in step 804, the identifier went back to zero, in step 806 it is checked whether the counter is equal to N. If the counter is not equal to N, the preceding steps are repeated from step 802. In step 807, if the counter is equal to N, a jump to track N is performed.

The method of performing a jump according to the present invention may be implemented as an integrated circuit adapted to be integrated in an optical disk device and / or recorder such as a CD or DVD player. The set of instructions loaded into the program memory allows the integrated circuit to perform a method of performing a jump. The set of instructions may be stored, for example, on a data medium such as a disk. The set of instructions can be read from the data medium for loading into the program memory of an integrated circuit, and then to perform its function.

Claims (5)

In the track jump unit for jumping the light beam 221 of the optical pickup device 201 from the first track of the disk 211 to the second track, Displacement means 202 controlled by a displacement signal 235 to displace the light beam; Reflected light beam detection means 203 for detecting the light beam reflected from the disk when the light beam from the optical pickup device is supplied to the disk, and generating a reflected light beam signal 231; Radiation error detection means 204 for generating a radial error signal 232 including at least one portion corresponding to the first track when at least one reflected light beam signal is supplied; Counting means (205) for associating at least one current track identifier (234) with the first track; Extended radial error calculating means for calculating, when the radial error signal is supplied, an extended radial error signal comprising a forged signal based on at least one portion of the radial error signal, the extended error signal comprising a portion having a track identifier associated therewith; 206), Generating means 207 which generates the displacement signal and is controlled by the extended radial error signal and the current track identifier so that a jump from the first track to the second track is performed by modifying the current track identifier Track jump unit comprising a. A method of performing a jump of a light beam of an optical pickup apparatus from a first track of a disc to a second track, the method comprising: Detecting a light beam reflected from the disk when the light beam from the optical pickup device is supplied to the disk, and generating a reflected light beam signal; Generating from the at least one reflected light beam signal a radial error signal comprising at least one portion corresponding to the first track; Associating at least one current track identifier with the first track; Computing from the radial error signal an extended radial error signal comprising a forged signal based on at least one portion of the radial error signal, the extended radial error signal comprising a portion having a track identifier associated therewith; Providing the extended radial error signal and a current track identifier to displacement means for displacing the light beam; Performing a jump from the first track to the second track by modifying the current track identifier. A method of performing a jump of a light beam of an optical pickup apparatus from a predetermined track of a disc to a desired track, The method is performed by jumping from one track to an immediately adjacent track until reaching the desired track, each of which is performed according to the method of claim 2 Way. An optical disc apparatus for reading data from an optical disc and / or writing data to the optical disc, The apparatus includes an track jump unit according to claim 1. A computer program comprising a set of instructions that, when loaded into a processor or computer, cause the processor or computer to perform the method of performing the jump of claim 2.