KR100530225B1 - Tracking control apparatus in optical disc drive and control method thereof - Google Patents

Abstract

Disclosed are a tracking control device and an control method thereof in an optical disc drive. According to the present invention, a tracking servo operation after a track jump can be performed more quickly and stably by determining the tracking lead-in time after the track jump in consideration of disturbance due to eccentricity of the optical disc or shaking of the tracking actuator.

Description

Tracking control apparatus in optical disc drive and control method thereof

The present invention relates to an optical disc drive such as a compact disc player (CDP) or a digital versatile disk player (DVDP), and stabilizes tracking pull-in after a track jump. The present invention relates to a tracking control device in an optical disk drive and a control method thereof.

The optical disc drive includes an optical pickup for condensing light on the signal recording surface of the optical disc, detecting the reflected light, and reading the information recorded on the optical disc. To this end, the optical pickup includes a light source, an objective lens, a photodetector, a focus actuator, and a focus actuator.

When the optical disk drive receives a track jump request signal during reproducing the optical disk, the optical disk drive applies a signal for instructing track jump to the tracking servo unit that controls the driving of the tracking actuator. When a signal for instructing track jump is received from the control unit that controls the overall operation of the optical disc drive, the tracking servo unit repeatedly generates a kick signal and a break signal at the tracking actuator so that the laser beam of the objective lens is the target track. on the target track. Then, the tracking servo unit performs tracking retrieval so that a reproducing operation on the target track is performed quickly after the track jump.

However, even when the brake signal is applied to the tracking actuator at the end of the track jump, a track cross occurs in which the tracking actuator deviates from the target track due to eccentricity or motor inertia. In this case, the tracking pull-in is not properly performed, which causes a problem of delayed resumption of playback after the track jump. In order to prevent the occurrence of the track cross, the brake is applied to the tracking actuator by performing a lens brake.

However, since the tracking retracting operation by the conventional lens brake does not consider the vibration displacement of the tracking actuator due to the eccentricity of the optical disk, the tracking actuator is prevented from deviating from the target track by simply using the lens brake signal. Tracking retraction after track jump is not done properly. That is, the state where the optical pickup is tracked in and out frequently occurs when the laser beam of the objective lens is not located at the center of the optical axis and is biased to one side. As a result, the moving range in which the objective lens can move is limited, and since the tracking servo operation is not performed stably, the performance of the system is degraded.

Accordingly, a technical object of the present invention is to provide a tracking control apparatus for an optical disc drive capable of stably performing a tracking servo operation after a track jump by determining a tracking entry point after a track jump based on the movement amount of the tracking actuator. To provide a control method.

In order to solve the above technical problem, the present invention is characterized in that the tracking entry point after the track jump in consideration of disturbance due to eccentricity of the optical disc or shaking of the tracking actuator.

The tracking control device according to the present invention compares the level of the signal detected by the tracking position detecting means for detecting the movement amount of the tracking actuator with a preset reference signal level after jumping to a desired target track based on the track jump command signal. Determine the tracking entry point.

To this end, the tracking control apparatus according to the present invention sets the minimum eccentric position search time when it is determined that the jumped track has reached the target track, and sets the lowest eccentric position that can minimize the influence of the eccentricity of the optical disk during the set time. Search. At this time, the tracking control apparatus determines the position when the level of the signal detected by the tracking position detecting means falls within the reference signal level range as the position that can be least affected by the eccentricity.

That is, the tracking control apparatus according to the present invention performs the tracking retracting operation at the lowest eccentric position found in the lowest eccentric position search section set after the track jump. In other words, the tracking control device according to the present invention delays the tracking retracting operation until the level of the detected signal falls within the reference signal level range.

In addition, the tracking control apparatus according to the present invention performs a lens brake to prevent the tracking actuator from being pushed to the residual kick signal applied for eccentricity or track jump at the point of tracking entry. In addition, after performing the lens brake operation for the set lens brake time, the tracking gain is increased for the fast tracking pulling-in operation. As described above, according to the present invention, the tracking retraction operation can be performed more quickly and stably by minimizing the influence of the eccentricity of the optical disc or the shaking of the tracking actuator after the track jump.

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

1 is a block diagram schematically showing an optical disk drive having a tracking control device according to a preferred embodiment of the present invention.

Referring to FIG. 1, an optical disc drive 100 according to the present invention includes an optical disc 100a, an optical pickup 110, an RF signal processor 120, a tracking servo unit 130, a tracking driver 140, and a main controller ( 150).

First, the optical disk drive 100 shown in FIG. 1 is a device for recording user data on the optical disk 100a or reproducing data recorded on the optical disk 100a. The compact disk player (CDP) or the digital versatile disk player (DVDP) is shown in FIG. ) And the like. In addition, FIG. 1 illustrates only blocks related to tracking control of the optical disc drive 100 for convenience of description.

The optical pickup 110 records user data by irradiating a predetermined laser beam on the signal recording surface of the optical disc 100a, irradiates a laser beam on the optical disc 100a, and then receives a laser beam reflected from the optical disc 100a. The data recorded on the optical disc 100a is read out. To this end, the optical pickup 110 includes a light source 111 for emitting a laser beam of a predetermined wavelength to the optical disc 100a, and a beam splitter 112 for reflecting and transmitting the laser beam emitted from the light source 111 at a predetermined ratio. ), The objective lens 113 for focusing the laser beam incident from the beam splitter 112 onto the recording surface of the optical disc 100a, and the laser beam reflected from the optical disc 100a are detected. Converting into electrical signal Photodetector 114, The tracking actuator 115 and the tracking actuator 115 for driving the objective lens 113 in the radial direction so that the optical pickup 110 accurately tracks the track formed on the optical disc 100a. And a flag sensor 116 applied to the tracking position detecting means for detecting the amount of movement of the vehicle. Here, the flag sensor 116 installs a light emitting source such as an LED on the tracking actuator 115 driving the objective lens 113, and detects the light reflected from the light emitting source to the objective lens 113 side. The sensor detects the movement amount of the objective lens 113, that is, the relative position of the tracking actuator 115.

The RF signal processor 120 generates a tracking error signal (hereinafter referred to as “TE”) for tracking servo using an electrical signal output from the optical pickup 110, and the generated TE signal is a tracking servo unit. Provided at 130. The RF signal processor 120 considers the type of the optical disc 100a or the type of the optical pickup 110 to perform a 3-Beam method, a differential phase detection (DPD) method, and a push-pull (PP) method. Either method may be used to generate the TE signal. Here, since the 3-Beam method, the DPD method, the PP method, and the like can be easily recognized by those skilled in the art, a detailed description thereof will be omitted.

The RF signal processor 120 generates a mirror (MIRR) signal based on the RF Sum signal output from the optical pickup 110. Here, the mirror (MIRR) signal is a signal generated in a portion where there is no data between the tracks when the optical pickup 110 reads the data recorded on the optical disc 100a. In addition, the RF signal processor 120 adjusts a tracking position signal (TPS: level) level detected by the flag sensor 116 that detects the movement amount of the objective lens 113, that is, the relative position of the tracking actuator 115. Amplify a predetermined level and output it. The mirror MIRR signal and the amplified tracking position signal TPS are provided to the tracking servo unit 130.

The tracking servo unit 130 includes a tracking servo controller 131 for tracking servo control.

The tracking servo control unit 131 controls the tracking servo operation and the specific recording of the optical disc 100a to control the laser beam emitted from the light source 111 to track the center of the recording track of the optical disc 100a under the control of the main controller 150. A track jump operation for moving the optical axis of the optical pickup 110 to the position is performed.

FIG. 2 is a block diagram schematically illustrating the tracking servo unit 130 shown in FIG. 1, and illustrates only a block for explaining a control process of the tracking servo unit 130 during a track jump.

As shown in FIG. 2, the tracking servo unit 130 includes a tracking servo controller 131, an equalizer 132, a track jump controller 133, a first selector 134, an ADC 135, and a lens brake controller. 136 and the second selector 137.

The equalizer 132 adjusts the gain of the TE signal output from the RF signal processor 120 under the control of the tracking servo controller 131. For example, the equalizer 132 raises the tracking gain according to the tracking gain up signal from the tracking servo controller 131.

The track jump controller 133 controls the jump speed under the control of the tracking servo controller 131 and generates a kick / brake signal for the track jump. The track jump control unit 133 performs track movement to a target track by using a predetermined track jump algorithm.

The first selector 134 outputs any one of a TE signal output from the RF signal processor 120 and a kick / brake signal output from the track jump controller 133 according to a control signal of the tracking servo controller 131. Optionally output For example, the first selector 134 outputs a TE signal output from the RF signal processor 120 when the control signal related to the tracking servo operation is received from the tracking servo controller 131, and from the tracking servo controller 131. Upon receiving the control signal related to the track jump, the kick jump or the brake signal output from the track jump controller 133 is output.

The ADC 135 converts the tracking position signal TPS amplified by the RF signal processor 120 into a digital signal.

The tracking servo controller 131 controls the track jump controller 133 to perform track movement to the target track in response to the track jump command signal from the main controller 150. The tracking servo controller 131 detects a track zero cross (TZC) signal from the TE signal provided from the RF signal processor 120 and tracks the optical axis of the optical pickup 110 based on the detected TZC signal. Count the number of tracks traversed. At this time, if it is determined that the number of jumped tracks has reached the target track, the tracking servo control unit 131 ends the track jump operation and sets the minimum eccentric position search time for determining the tracking entry time.

The tracking servo controller 131 switches the second selector 137 to output the preset reference voltage Vref during the set minimum eccentric position search time. That is, the tracking actuator 115 is held for the lowest eccentric position search time, and then the lowest eccentric position is searched based on the tracking position signal TPS applied from the ADC 135. The tracking servo controller 131 searches the lowest eccentric position by comparing the signal level applied from the ADC 135 with the preset reference signal level during the set minimum eccentric position search time, and performs the tracking retracting operation at the found lowest eccentric position. Let's do it. At this time, the tracking servo controller 131 moves the position where the optical axis of the optical pickup 110 is located when the signal level applied from the ADC 135 is within a preset reference signal level range to the lowest eccentric position of the optical disc 100a. To judge. On the other hand, when the level of the tracking position signal TPS applied from the ADC 135 is out of the reference signal level range, the tracking servo controller 131 performs the tracking ingress until the signal level falls within the reference signal level range. Delay. Here, the reference signal level range means a range capable of stably performing the tracking lead-in operation by minimizing the influence of the eccentricity of the optical disc 100a.

The lens brake control unit 136 uses the mirror (MIRR) signal and the track zero cross (TZC) signal to prevent the tracking actuator 115 from being pushed due to an eccentric or residual kick signal after the track jump. Generates a lens brake signal for controlling. The lens break signal is generated only during the lens break time set by the tracking servo controller 131. That is, the lens brake control unit 136 cuts off the tracking drive signal TRD to the reference voltage to prevent the track cross from being generated by the eccentricity or the kick remaining speed at the track entry point after the track jump. A lens brake signal is outputted.

The second selector 137 is a signal generated by the switching operation of the first selector 134 based on the lens brake signal of the lens brake controller 136 or a reference voltage preset for driving the tracking driver 140 ( Vref) is output as the tracking drive signal TRD. For example, when no track cross occurs after the track jump, the second selector 137 outputs a signal generated by the switching operation of the first selector 134 as the tracking drive signal TRD. In contrast, when a track cross is generated, the second selector 137 outputs a preset reference voltage as the tracking driving signal TRD. Accordingly, the phenomenon that the tracking actuator 115 deviates from the target track by the residual kick component or the eccentricity of the optical disc 100a after the track jump can be prevented.

The tracking driver 140 amplifies the tracking drive voltage TRD output from the second selector 137 to a power level suitable for driving the tracking actuator 115 and supplies the tracking driver 115 to the tracking actuator 115.

The main controller 150 controls the overall operation of the optical disc drive 100 according to various control programs stored in a memory unit (not shown). For example, the main controller 150 controls the operation of the tracking servo unit 130 based on a key input signal applied through the user interface.

FIG. 3 is a flowchart illustrating a tracking control method of the optical disc drive shown in FIG. 2.

1 to 3, when a track jump command signal is received from the main controller 150 while operating in a normal playback mode in which information recorded on the optical disc 100a is sequentially reproduced (S310, S315), tracking is performed. The servo controller 131 controls the track jump controller 133 to perform a track jump operation (S320). That is, the tracking servo controller 131 controls the first selector 134 to turn off the tracking servo operation and perform the track jump operation. The track jump control unit 133 generates a kick signal and a brake signal, and performs a track jump using a predetermined track jump algorithm (eg, a jump algorithm based on speed control).

The tracking servo controller 131 counts the number of tracks that are jumped while the track jump is performed, and determines whether the number of jumped tracks reaches the target track (S325). If it is determined that the jump is not as much as the target track, the tracking servo controller 131 controls the track jump controller 133 to continuously perform the track jump operation.

On the contrary, if it is determined in step S325 that the number of jumped tracks reaches the target track number, the tracking servo controller 131 ends the track jump operation and sets the minimum eccentric position search time for searching for the lowest eccentric position ( S330).

The tracking servo controller 131 searches the lowest eccentric position by comparing the level of the track position signal TPS converted by the ADC 135 with a preset reference signal level. At this time, the tracking servo controller 131 controls the second selector 137 to output the preset reference voltage Vref as the tracking drive signal TRD to hold the tracking actuator 115.

When the lowest eccentric position is found, the tracking servo control unit 131 turns on the tracking servo operation that controls the laser beam emitted from the light source 111 to track the recording track of the optical disc 100a (S335, S340). . Here, the tracking servo on means that the optical pickup 110 is pull-in.

The tracking servo control unit 131 checks the track position signal TPS detected by the flag sensor 116 during the lowest eccentric position search time, and tracks the servo until the detected signal level falls within a preset reference signal level range. Keep it off. That is, the tracking servo control unit 131 may be configured such that the optical axis of the optical pickup 110 is least affected by the eccentricity of the optical disc 100a when the detected track position signal TPS level is within a preset reference signal level range. It is determined that the position is located, and performs the tracking pull-in operation at this position. This makes it possible to stably perform the tracking control operation after the track jump.

On the other hand, if a track cross occurs at the time when the optical pickup 110 is tracked in, the tracking servo controller 131 may apply a mirror MIRR signal and a track zero cross signal TZC for a predetermined lens break time. The lens brake is performed to block the tracking driving signal TRD by the reference voltage Vref by using the control unit 350. Here, the lens brake is an operation for preventing the tracking actuator 115 from being pushed due to the eccentricity of the optical disc 100a or the remaining amount of the kick signal generated from the track jump controller 133 after the track jump. The description of the operation is omitted.

When the set lens break time has elapsed, the tracking servo controller 131 ends the lens brake operation and generates a tracking gain up signal to the equalizer 132 to increase the tracking gain. The equalizer 132 increases the tracking gain by a predetermined level based on the tracking gain up signal from the tracking servo controller 131 (S360).

4 is a waveform diagram illustrating the tracking control method illustrated in FIG. 3. FIG. 4A is a waveform diagram illustrating a tracking error signal TE, and FIG. 4B is a diagram. 4 is a waveform diagram showing a tracking drive signal TRD which is an output signal of the tracking servo unit 130 shown in FIG. 2, and FIG. 4C shows the tracking position signal TPS detected by the flag sensor shown in FIG. 1. It is a waveform diagram which shows.

Referring to FIG. 4, the tracking control section includes a speed control section TI, a lowest eccentric position search section T2, a lens brake section T3, and a stabilization section T4. The tracking servo control unit 131 controls the track jump control unit 133 to jump by the desired number of tracks during the speed control section T1 (S320 in FIG. 3), and when it is determined that the number of jumped tracks reaches the target track number ( S325), the track jump operation is stopped and the lowest eccentric position is searched based on the tracking position signal detected by the flag sensor 116 during the lowest eccentric position search section T2. When the lowest eccentric position is found, the tracking inlet operation is performed at the found lowest eccentric position (S340). When a track cross occurs during the tracking servo operation, the lens brake section T3 is entered. During the lens brake section T3, the lens brake controller 136 prevents the tracking actuator 115 from being pushed by an eccentric or residual kick signal. In order to block the tracking driving signal TRD to a reference voltage, a lens brake is performed (S345 and S350). After the lens brake period T3 has elapsed, a normal regeneration mode is entered after passing the gain up period T4 for increasing the tracking gain for a fast tracking pulling-in operation (S360).

As described above, according to the present invention, by determining the tracking entry time point in consideration of disturbance due to eccentricity of the optical disc 100a after the track jump or shaking of the tracking actuator 115, the tracking servo operation performed after the track jump can be performed more quickly. Can be performed stably.

As described so far, according to the tracking control apparatus and control method thereof in the optical disc drive according to the present invention, the amount of movement of the tracking actuator detected by the tracking position detecting means at the time of track jump from the track currently being played to the desired target track is determined. On the basis of this, the tracking entry point after the track jump is determined. That is, by determining the tracking entry time by minimizing the influence of disturbance by the eccentricity of the optical disc or the shaking of the tracking actuator, the tracking servo operation after the track jump can be performed more quickly and stably.

Although the present invention has been described in detail with reference to exemplary embodiments above, those skilled in the art to which the present invention pertains can make various modifications to the above-described embodiments without departing from the scope of the present invention. I will understand. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be defined by the claims below and equivalents thereof.

1 is a block diagram schematically showing an optical disk drive having a tracking control device according to a preferred embodiment of the present invention;

FIG. 2 is a block diagram schematically illustrating the tracking servo unit shown in FIG. 1;

3 is a flowchart illustrating a tracking control method in the optical disc drive shown in FIG. 2, and

 FIG. 4 is a waveform diagram illustrating the tracking control method illustrated in FIG. 3.

Explanation of symbols on the main parts of the drawings

100: optical disc drive 110: optical pickup

113: objective lens 115: tracking actuator

116: flag sensor 120: RF signal processing unit

130: tracking servo unit 131: tracking servo control unit

140: tracking driver 150: main control unit

Claims (12)

A track jump controller configured to generate a kick signal and a brake signal in response to the track jump signal, and perform a track jump using a predetermined track jump algorithm; An A / D converter for converting the signal level detected by the tracking position detection sensor to detect the movement amount of the tracking actuator into a digital signal; And If it is determined that the number of jumped tracks has reached the target track, the lowest eccentric position is searched by comparing the signal level converted by the A / D converter with a preset reference signal level, and the tracking retracting operation is performed when the lowest eccentric position is searched. Tracking servo control unit for performing a; tracking control device in an optical disk drive comprising a. The method of claim 1, And the tracking servo control unit performs the tracking retracting operation when the detected signal level falls within the reference signal level range. The method of claim 1, And the tracking servo control unit delays the tracking retracting operation when the converted signal level is out of the reference signal level range. The method of claim 1, And a first selector configured to output one of a tracking error signal for tracking servo operation of the tracking actuator and the kick / break signal generated by the track jump controller. . The method of claim 4, wherein The first selector outputs the kick / break signal generated by the track jump controller when the track jump signal is received from the tracking servo controller, and outputs the tracking error signal when the tracking lead performing signal is received. Tracking control device in the optical disk drive. The method of claim 1, A lens brake control unit configured to generate a lens brake signal to cut a tracking drive signal for driving the tracking actuator to a predetermined reference voltage based on a track zero cross signal and a mirror signal when a tracking phenomenon occurs in the tracking actuator; And And a second selector configured to output one of the output signal of the first selector and the reference voltage as the tracking drive signal based on the lens brake signal. The method of claim 6, And the tracking servo controller is configured to hold the tracking actuator by blocking the tracking drive signal to the reference voltage when searching for the latest eccentric position in order to determine the tracking entry time. Performing a track jump using a predetermined track jump algorithm in response to the track jump signal; Searching for the lowest eccentric position based on the signal level detected by the tracking position detecting sensor that detects the movement amount of the tracking actuator if it is determined that the number of jumped tracks has been reached; And And when the lowest eccentric position is found, performing a tracking retracting operation at the found lowest eccentric position. The method of claim 8, In the search for the lowest eccentric position, the lowest eccentric position is searched by comparing the detected signal level with a preset reference signal level. The method of claim 9, And said tracking retracting operation is performed when said detected signal level falls within said reference signal level range. The method of claim 8, And performing a lens break based on a track zero cross signal and a mirror signal for a predetermined lens break time when a track cross occurs at the time of performing the tracking inlet operation. The method of claim 8, The tracking control method of the optical disc drive, characterized in that to hold the tracking actuator by blocking the tracking drive signal to a predetermined reference voltage when the search for the lowest eccentric position.