JP2006344302A - Thread motor drive control method in optical disk drive - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a track jump control method suited to an optical disk drive configured to use an optical pickup for reproducing the signals recorded on an optical disk. <P>SOLUTION: It makes track jumping to a target track on an optical disk by turning off the tracking servo circuit and the thread motor servo circuit. When the irradiated position with the laser beam reach the target track, it turns on the tracking servo circuit, and checks whether the tracking error signal level is within the predetermined limit or not. Then, it turns on the thread motor servo circuit when it is within the predetermined limit. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a thread motor drive control method for an optical disc apparatus configured to read a signal recorded from an inner circumference side to an outer circumference side of an optical disc with an optical pickup.

  2. Description of the Related Art Optical disc apparatuses that perform a reproduction operation by reading a signal with an optical pickup from an optical disc in which information data such as music is recorded by a digital signal are widespread. As representative examples of such optical disc apparatuses, CDs and DVDs are used. There is an optical disk device that uses an optical disk called.

  Such an optical disc apparatus is configured to cause the laser light to follow a track provided on the signal surface of the optical disc by biasing an objective lens incorporated in the optical pickup, and the control operation is performed as a tracking operation. This is called a control action. The optical disk apparatus also supplies a driving signal called a kick pulse to a tracking coil that biases the objective lens during a pause operation, a fast-forward operation, a rewind operation, and a search operation for searching for a desired position. In general, it has a function capable of performing a track jump operation for displacing light to another track.

  When the target track is away from the current position, the laser beam is moved to the target track position by moving the optical pickup body by the rotational force of a motor called a sled motor and biasing the objective lens. It is configured to let you.

In the case where the laser beam is displaced to the target track position by the track jump operation, a technique has been developed to quickly perform the search operation by changing and controlling the gain of the tracking servo circuit when the laser beam is displaced to the target track position. (For example, see Patent Document 1).
Japanese Patent Application Laid-Open No. 2004-241065

  The operation of displacing the laser beam to the target track position by the track jump operation accompanying the search operation is performed with the tracking servo circuit and the sled motor servo circuit turned off, and the irradiation position of the laser beam is determined by the track count operation. When it is determined that the target position has been reached, the tracking servo circuit and the sled motor servo circuit are turned on.

  The rotation driving operation of the optical disk in the optical disk apparatus is performed by rotating the turntable on which the optical disk is mounted by a spindle motor. However, the rotation of the optical disk is caused by the eccentricity of the optical disk itself and the eccentricity of the optical disk mounted on the turntable. Swelling will occur. When the rotation characteristic of the optical disk has a wave, there is a characteristic that the level of the tracking error signal changes according to the magnitude of the wave.

The operation to turn on the sled motor servo circuit after the tracking servo circuit is turned on is performed, but when the level of the tracking error signal at the time of switching the sled motor servo circuit from the off state to the on state is large, The thread motor rotation control operation cannot be performed normally, and a phenomenon of track jumping occurs. When such a track jump occurs, there is a problem that the target track cannot be accurately captured.

  The present invention intends to provide a thread motor drive control method capable of solving such a problem.

  The present invention performs the track jump operation to the target track on the optical disc and the displacement operation of the optical pickup body by the sled motor in a state where the tracking servo circuit and the sled motor servo circuit are turned off, and the irradiation position of the laser beam When the track reaches the target track, the tracking servo circuit is turned on, and it is detected whether the level of the tracking error signal is within a predetermined range, and when it is within the predetermined range, the sled motor servo circuit is turned on. It is configured.

  In addition, according to the present invention, the level detection operation can be reliably performed by configuring the tracking error signal level detection operation every predetermined time shorter than the period in which the level of the tracking error signal is within the predetermined range. Has been.

  The present invention is configured such that the average value of the tracking error signal level detected a predetermined number of times every predetermined time is set to a detection level for performing a determination operation as to whether or not it is within a predetermined range.

  Further, the present invention is configured to change the interval for performing the level detection operation of the tracking error signal in accordance with the rotation speed of the optical disc.

  The present invention is configured to turn on the sled motor servo circuit when the level of the tracking error signal detected by the tracking error signal level detection operation does not fall within the predetermined range within the set time.

  Further, the present invention is configured to perform a track jump operation to the target track when the track acquired is not the target track when the level of the tracking error signal does not fall within the predetermined range within the set time.

  In the present invention, the time for detecting the tracking error signal level is set to be the time required for one or half rotation of the optical disc.

  The present invention performs the track jump operation to the target track on the optical disc and the displacement operation of the optical pickup body by the sled motor in a state where the tracking servo circuit and the sled motor servo circuit are turned off, and the irradiation position of the laser beam When the track reaches the target track, the tracking servo circuit is turned on, and it is detected whether the level of the tracking error signal is within a predetermined range, and when it is within the predetermined range, the sled motor servo circuit is turned on. In other words, since the sled motor servo circuit is turned on when the optical disk rotation is less affected by eccentricity or the like, the target track can be accurately captured.

  In the present invention, the level detection operation of the tracking error signal is performed every predetermined time shorter than the period in which the level of the tracking error signal is within the predetermined range, so that the time point when the level of the tracking error signal falls within the predetermined range. Can be reliably performed.

  In the present invention, since the average value of the tracking error signal level detected a predetermined number of times every predetermined time is set to a detection level for determining whether or not it is within a predetermined range, the detection operation that suppresses the influence of noise Can be done.

  Further, according to the present invention, the interval for performing the level detection operation of the tracking error signal is changed in accordance with the rotation speed of the optical disk, so that the level detection operation of the tracking error signal is accurately performed even if the rotation speed of the optical disk is changed. Can be done.

  In the present invention, the sled motor servo circuit is turned on when the level of the tracking error signal detected by the level detection operation of the tracking error signal does not fall within the predetermined range within the set time. It is possible to return to a state in which a later tracking control operation is performed.

  In addition, the present invention can be applied to the target track when the track acquired by changing the gain of the tracking servo circuit to a steady gain when the level of the tracking error signal does not fall within the predetermined range within the set time is not the target track. Since the track jump operation is performed, the target track can be reliably captured.

  In the present invention, since the time for performing the tracking error signal level detection operation is set to be the time required for one or half rotation of the optical disc, the track captured by the tracking control operation by the tracking servo circuit is recorded. The track can be close to the target track.

  The present invention controls the rotation operation of the sled motor performed by the search operation by detecting the level change of the tracking error signal obtained from the optical pickup.

  FIG. 1 is a flowchart showing a sled motor drive control method of the present invention, FIG. 2 is a block circuit diagram showing an embodiment of an optical disk apparatus according to the present invention, and FIG. 3 is a signal waveform diagram for explaining the operation of the present invention. is there.

  In FIG. 2, reference numeral 1 denotes an optical disk that is rotationally driven by a spindle motor (not shown), and 2 denotes a laser diode (not shown) that irradiates the optical disk 1 with laser light and is reflected from the signal surface of the optical disk 1. The optical pickup is incorporated with a photodetector 3 that receives the laser beam to be emitted, and is provided with a tracking coil 5 that biases the objective lens 4 in the tracking direction, and the optical motor is driven by the rotation of the sled motor 6. The main body of the pickup 2 is configured to be displaced in the radial direction of the optical disc 1.

  In such an optical pickup 2, the tracking error detection operation is performed, for example, by a known method called a three-beam method. Reference numeral 7 denotes a tracking error signal generation circuit that generates a tracking error signal as shown in FIG. 3 based on a signal obtained from a photodetector 3 incorporated in the optical pickup 2, and 8 denotes the tracking error signal generation circuit 7. A tracking equalizer circuit 9 that corrects the frequency of the error signal output from the tracking equalizer 9 receives a tracking control signal input through the tracking equalizer circuit 8 and supplies a driving signal corresponding to the tracking control signal to the tracking coil 5. It is a coil drive circuit.

  In such a circuit, the tracking error signal generation circuit 7, the tracking equalizer circuit 8, and the tracking coil drive circuit 9 constitute a circuit for performing a tracking control operation for causing the laser beam to follow the signal track, that is, a tracking servo circuit. Thus, the control operation for causing the laser beam to follow the signal track provided on the optical disc 1 is performed.

  A system control circuit 10 is provided to control the operation of the optical disk apparatus, and is constituted by a microcomputer. Reference numeral 11 denotes a sled motor driving circuit for supplying a driving signal to the sled motor 6. The operation of the sled motor driving circuit is controlled by the system control circuit 10 and the rotational driving operation is controlled based on a signal obtained from the tracking coil driving circuit 9. It is comprised so that.

  A kick pulse generation circuit 12 outputs a kick pulse to the tracking coil drive circuit 9 when performing a track jump operation for biasing the objective lens 4. The system control circuit 10 controls the kick pulse generation operation. It is configured as follows. Reference numeral 13 denotes a first selection switch for selecting a signal input from the tracking equalizer circuit 8 and a signal output from the kick pulse generation circuit 12 as a signal input to the tracking coil drive circuit 9, and the system control circuit The selection operation is controlled by the first switch circuit 14 controlled by 10.

  Reference numeral 15 denotes a sled servo equalizer circuit which receives a tracking error signal via the tracking equalizer circuit 8 and generates a signal for controlling the rotation operation of the sled motor 6, and 16 displaces the optical pickup 2 main body during the search operation. This is a sled motor drive signal generation circuit that generates a drive signal corresponding to the amount of displacement when necessary.

  In such a circuit, a tracking error signal generation circuit 7, a tracking equalizer circuit 8, a sled servo equalizer circuit 15 and a sled motor drive circuit 11 perform a rotation control operation of the sled motor 6 so that the laser light follows the signal track. That is, a sled motor servo circuit is configured.

  17 is a second selection switch for selecting a signal input from the thread servo equalizer circuit 15 and a signal output from the thread motor drive signal generation circuit 16 as a signal input to the thread motor drive circuit 11; The second switch circuit 18 controlled by the system control circuit 10 is connected so that the selection operation is controlled.

  Reference numeral 19 denotes a sampling circuit to which a tracking error signal generated and output from the tracking error signal generation circuit 7 is input. Based on the signal output from the system control circuit 10, a sampling operation of the tracking error signal is performed at a predetermined interval. Is configured to do. An AD converter circuit 20 converts the level of the tracking error signal, which is an analog signal sampled by the sampling circuit 19, into a digital signal. The converted digital signal is input to the system control circuit 10. ing.

In such a configuration, the on / off operation of the tracking servo circuit is controlled by switching the first selection switch 13 by the first switch circuit 14 and the gain of an amplifier circuit (not shown) incorporated in the tracking equalizer circuit 8 is controlled. It is configured so that the gain change operation of the tracking servo circuit can be performed by being controlled by the system control circuit 10. Further, the on / off operation of the sled motor servo circuit is controlled by switching the second selection switch 17 by the second switch circuit 18.

  As described above, the optical disk apparatus according to the present invention is configured. Next, the operation will be described. The reading operation of the signal recorded on the optical disc 1 includes a focus control operation for rotating the optical disc 1 at a desired rotational speed and focusing the laser beam on the signal surface, and a tracking control operation for causing the laser beam to follow the signal track. It is performed in the state where has been performed.

  In a state in which a signal recorded on the optical disc 1 is read, the first selection switch 13 and the second selection switch 17 are in the illustrated state, and both the tracking servo circuit and the sled motor servo circuit are in the on state.

  In this embodiment, a signal obtained from the photodetector 3 incorporated in the optical pickup 2 is input to the tracking error signal generation circuit 7, and the tracking error signal generation circuit 7 is based on the input signal. 3 is generated. The tracking error signal output from the tracking error signal generation circuit 7 is input to the tracking equalizer circuit 8 to be frequency corrected, amplified by the amplifier circuit, and then input to the tracking coil drive circuit 9 through the first selection switch 13. Is in a state.

  The tracking error signal output from the tracking equalizer circuit 8 is input to the sled servo equalizer circuit 15 to be frequency-corrected and input to the sled motor drive circuit 11 through the second selection switch 17.

  When the tracking error signal whose frequency has been corrected by the tracking equalizer circuit 8 is input to the tracking coil drive circuit 9, a tracking drive signal is supplied from the tracking coil drive circuit 9 to the tracking coil 5. Such a signal acts to bias the objective lens 4 in the direction of decreasing the level of the tracking error signal. As a result of controlling the position of the objective lens by such a signal, an operation of causing the laser beam to follow the signal track, that is, a tracking control operation is performed.

  In this way, the tracking control operation for causing the laser beam to follow the signal track is performed. The gain of the tracking servo circuit in such a case is the normal operation, that is, when the signal recorded on the optical disc 1 is reproduced. The required steady gain is set.

  As described above, the tracking control operation by the tracking servo circuit is performed. However, when the deflection operation of the objective lens 4 is performed to an allowable range, the further deflection operation of the objective lens 4 cannot be performed. In this state, a drive signal is supplied from the thread motor drive circuit 11 to the thread motor 6. That is, the objective lens 4 can be returned from the biased position to the neutral position by moving the main body of the optical pickup 2 by the rotational operation of the sled motor 6. The moving operation of the optical pickup 2 main body by the sled motor 6 is performed every time the reading position on the optical disc 1 is moved. Such a moving operation is performed by a servo operation by a sled motor servo circuit. . Since such a drive control operation for the sled motor 6 is well known, its description is omitted.

  Although the tracking control operation is performed as described above, the search operation for moving the laser beam irradiated from the optical pickup 2 to the target track at the target position on the optical disc 1 will be described next.

  Such a search operation is performed by a biasing operation of the objective lens 4 by applying a kick pulse signal to the tracking coil 5 and a moving operation of the optical pickup 2 main body by the sled motor 6. That is, when the position of the target track is close to the current position, the search operation to the target track is performed only by the biasing operation of the objective lens 4, and when the position of the target track is far from the current position, the sled motor 6 is performed by the movement operation of the optical pickup 2 main body 6 and the deflection operation of the objective lens 4.

  The moving operation of the laser beam to the target track is performed by the biasing operation of the objective lens 4 and the moving operation of the optical pickup 2 main body by the sled motor 6. This is done by counting the number of tracks by detecting the signal obtained when crossing. Since such an operation is well known, its description is omitted.

  In a search operation when the position of the target track is close to the current position, that is, a search operation in which the position of the laser beam can be moved to the target track only by the biasing operation of the objective lens 4, the first selection switch 13 is set. The search operation is performed by switching to the opposite side of the state shown in the figure by the first switch 14.

  In such a case, a kick pulse necessary for moving the laser beam to the position of the target track is generated from the kick pulse generation circuit 12 and the kick pulse is sent to the tracking coil drive circuit 9 via the first selection switch 13. An input operation is performed. As a result, since the kick pulse is supplied from the tracking coil drive circuit 9 to the tracking coil 5, the objective lens 4 is deflected and the laser beam is moved to the target track based on the number of tracks jumped. I can do it.

  When the laser beam moves to the position of the target track, the operation of switching the first selection switch 13 back to the state shown in the figure and increasing the gain of the amplifier circuit incorporated in the tracking equalizer circuit 8 is performed. In other words, it is possible to increase the capture power for the target track by turning on the tracking servo circuit and increasing the gain of the tracking servo circuit. When the target track capturing operation is performed by such an operation, the operation of changing the gain of the tracking servo circuit to the normal gain is performed, and the normal tracking servo operation is performed. Therefore, the reproduction operation of the signal recorded on the target track can be started.

  The search operation described above is an operation when the position of the target track is close to the current position, that is, when the moving operation of the optical pickup 2 main body by the sled motor 6 is not required. Will be described in the case where is located away from the current position, that is, when the movement operation of the optical pickup 2 main body by the sled motor 6 is required.

  Next, a thread motor drive control method which is the gist of the present invention will be described with reference to a flowchart shown in FIG. 1 and a signal waveform diagram shown in FIG.

  When the search operation for the target track is started, the control operation for the search operation by the system control circuit 10 is started. When such an operation is started, the control operation for the first switch circuit 14 and the second switch circuit 18 by the system control circuit 10 is performed, and both the first selection switch 13 and the second selection switch 17 are opposite to the illustrated state. Switched to the side.

By performing such a switching operation, both the tracking servo circuit and the sled motor servo circuit are turned off (step A). In such a state, the track jump operation for the search operation, that is, the kick pulse generation operation by the kick pulse generation circuit 12 and the sled motor drive signal generation operation by the sled motor drive signal generation circuit 16 are started (step B). .

  Such a track jump operation is performed by moving the optical pickup 2 main body by the rotational drive operation of the sled motor 6 to move the irradiation position of the laser light closer to the target track, and then by the biasing operation of the objective lens 4. Is performed by an operation of displacing the track on the target track. When such an operation is performed, an operation of counting the number of tracks traversed is performed.

  By detecting the number of traversed tracks, a detection operation is performed to determine whether the laser beam has reached the target track position (step C). If it is determined in step C that the laser beam has reached the position of the target track, the biasing operation on the objective lens 4 and the driving operation on the sled motor 6 are released.

  Further, the control operation for the first switch circuit 14 by the system control circuit 10 is performed, the first selection switch 13 is switched to the illustrated state, and the tracking servo circuit is turned on (step D). When the tracking servo circuit is turned on, a tracking error signal generation operation is performed by the tracking error signal generation circuit 7, and a tracking error signal having a waveform shown in FIG. 3 is output.

  In FIG. 3, a period in which the level of the tracking error signal is larger than the reference level VR indicates a state in which the track of the optical disk 1 is shifted to the outer peripheral side due to the eccentricity of the optical disk 1, and conversely, a period smaller than the reference level VR is The state where the track of the optical disc 1 is shifted to the inner peripheral side is shown. Also, in the figure, the values of + α and −α representing the level of the tracking error signal are values set for performing a control operation to be described later according to the level of the tracking error signal.

  When the operation in step D is performed, the tracking control operation is performed. In such a state, the tracking error signal level detection operation is performed every predetermined time (step E). Such a tracking error signal level detection operation is performed by a sampling operation by the sampling circuit 19, and the sampled level value is converted into a digital signal by the AD converter circuit 20 and input to the system control circuit 10. Therefore, the system control circuit 10 can recognize the level of the tracking error signal detected.

  The tracking error signal level detection operation is performed in order to recognize whether or not the detection value L, which is the level of the tracking error signal, is VR−α <L <VR + α. In FIG. The sampling period is set so that the sampling operation is performed.

  In the present embodiment, for example, when the time required for one rotation of the optical disk 1 is 150 ms, the level detection operation of the tracking error signal is performed at intervals of 2 ms, and the average of the tracking error signal level obtained by several sampling operations is obtained. A value is calculated and set to a detection value L.

An operation for determining whether or not the detection value L obtained in this way is within a predetermined level is performed (step F). If it is determined in step F that it is not within the predetermined level, that is, if it is determined that the time when the detection operation is performed is in the period indicated by T1 or T2 in FIG. A determination operation is performed as to whether or not a set time has elapsed since the error signal level detection operation was started (step G). Such a set time is set based on the time required for one rotation of the optical disc 1, but as is apparent from FIG. 3, the detected value L which is the level of the tracking error signal during one rotation is VR−α <L. <There are two periods in which VR + α is entered. If the time required for one rotation is 150 ms, the half rotation may be set from 75 ms to 80 ms.

  If the set time has not elapsed in step G, the process returns to step E and the tracking error signal level detection operation is performed. As described above, the level detection operation of the tracking error signal is performed. If it is determined in step F that the detection value L is within the predetermined level, that is, if it is determined that it is within the period indicated by T3, The control operation for the two-switch circuit 18 is performed, the second selection switch 17 is switched to the illustrated state, and the sled motor servo circuit is turned on (step H).

  By performing such an operation, a normal tracking control operation by the tracking servo circuit and a sled motor servo operation by the sled motor servo circuit are performed, and the track can be irradiated with laser light following the track. In this case, since the sled motor servo circuit is turned on when the level of the tracking error signal is small, that is, when the waviness due to the eccentricity of the optical disc 1 is small, the track skip does not occur and the target track Can be captured accurately.

  If it is determined in step G that the set time has elapsed since the tracking error signal detection operation was started, the system control circuit 10 performs the operation of step H, that is, the control operation for turning on the sled motor servo circuit. . Even in such a case, the normal tracking control operation by the tracking servo circuit and the sled servo operation by the sled motor servo circuit are performed, and the control operation for following and irradiating the track with the laser beam is performed. Since the operation of turning on the sled motor servo circuit is performed when the level is high, that is, when the waviness due to the eccentricity of the optical disc 1 is large, the possibility of track skipping increases.

  If such a control operation is performed and the captured track is not the target track, a search operation from the position to the target track is performed, but in such a case, the target track is close, so the search is performed. The operation can be performed only by the deflection operation of the objective lens 4. Therefore, an operation for displacing the position of the laser beam to the target track can be performed.

  In this description, the detection value L used in the tracking error signal level determination operation is an average value of the levels obtained by several sampling operations. However, the detection value L is determined by one measurement value. You can also do so. If the interval for performing the level detection operation is changed in accordance with the rotation speed of the optical disc 1, the level detection operation of the tracking error signal suitable for the rotation speed of the optical disc 1 can be performed.

  In this description, the set time for performing the level detection operation of the tracking error signal is set to the time required for the optical disk 1 to make a half rotation, but may be set to the time required for one rotation.

It is a flowchart which shows the sled motor drive control method of this invention. 1 is a block circuit diagram showing an embodiment of an optical disc apparatus according to the present invention. It is a signal waveform diagram for demonstrating operation | movement of this invention.

Explanation of symbols

1 Optical disc
2 Optical pickup
3 Photodetector
4 Objective lens
5 Tracking coil
7 Tracking error signal generation circuit
8 Tracking equalizer circuit
DESCRIPTION OF SYMBOLS 9 Tracking coil drive circuit 10 System control circuit 11 Thread motor drive circuit 12 Kick pulse generation circuit 15 Thread servo equalizer circuit 16 Thread motor drive signal generation circuit 19 Sampling circuit

Claims (8)

An optical disc apparatus configured to move a laser beam to a target track position by performing a combination of a track jump operation for biasing an objective lens incorporated in an optical pickup and a displacement operation of the optical pickup body by a sled motor. This is a sled motor drive control method, which performs the track jump operation to the target track on the optical disc and the displacement operation of the optical pickup body by the sled motor with the tracking servo circuit and sled motor servo circuit turned off, and the laser. When the light irradiation position reaches the target track, the tracking servo circuit is turned on and whether the level of the tracking error signal is within a predetermined range is detected. Sled motor drive control method of the optical disc apparatus being characterized in that so as to turn on the. 2. The sled motor drive control method according to claim 1, wherein the tracking error signal level detection operation is performed every predetermined time shorter than a period in which the level of the tracking error signal is within a predetermined range. 3. The sled motor drive control method according to claim 2, wherein an average value of the levels detected a predetermined number of times every predetermined time is set as a detection level for performing a determination operation as to whether or not the predetermined level is within a predetermined range. 3. The thread motor drive control method according to claim 2, wherein an interval for performing the level detection operation is changed in accordance with a rotation speed of the optical disk. 2. The sled motor servo circuit is turned on when the level of the tracking error signal detected by the level detection operation of the tracking error signal does not fall within a predetermined range within a set time. Thread motor drive control method. 6. The sled motor drive control method according to claim 5, wherein when the track captured by the tracking control operation is not the target track, a track jump operation to the target track is performed. 6. The sled motor drive control method according to claim 5, wherein the set time is set to a time required for half rotation of the optical disc. 6. The sled motor drive control method according to claim 5, wherein the set time is set to a time required for one rotation of the optical disk.

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