KR100579622B1 - Control method for servo of optical recorder - Google Patents

Abstract

The present invention relates to a servo control method of an optical recorder, and if the type of the loaded optical record carrier is determined to be a recordable type, checking the data recording state of the optical record carrier and not recording data on the optical record carrier. If it is not, performing the prediction determination in the recording mode, initializing the recording related setting values, and then performing the servo control including the tracking servo by the push-pull method; and in the reproducing mode if the data is recorded on the optical recording medium. Performing a servo control including a tracking servo by a phase difference detection (DPD) method, and when the optical recording medium is only used in the recording mode, unnecessary initialization is not performed, thereby reducing loading time and initial tracking. The servo control performance is improved by using the DPD method, which has better performance than the push-pull method. There point.

Description

CONTROL METHOD FOR SERVO OF OPTICAL RECORDER}

1 is a block diagram of a general optical disc recording and reproducing apparatus;

2 is a view showing an example of generating a tracking error signal by a phase difference detection (DPD) method from a general photo detector;

3 is a view showing the principle of a general phase difference detection method,

4 is a flowchart showing a servo control process of the optical recorder according to the present invention.

<Explanation of symbols for the main parts of the drawings>

101: optical disk 102: optical pickup

103: high frequency and servo error generating unit 104: servo control unit

105: focus servo driver 106: tracking servo driver

The present invention relates to a servo control method of an optical recorder, and more particularly, to determine a type of an optical record medium and to selectively predict a recording mode and a reproduction mode to perform differentiated servo control for each predicted mode. It relates to a servo control method of a regenerator.

In general, an optical recording medium may be a play-only disc such as a CD-ROM (CD-Read Only Memory) or a DVD-ROM, or a CD-Write Once Read Many (CD-WORM) or a DVD-R depending on whether recording is possible. And write-once discs such as CD-RW (CD-Rewritable), DVD-RW, DVD-RAM (DVD-Random Access Memory), and the like.

1 is a general block diagram of an optical disk recording and reproducing apparatus for recording data on DVD-based optical disks and reproducing the recorded data, wherein the optical pickup 102 condenses on the objective lens under the control of the servo control unit 104. The light beam is placed on the signal track of the optical disk 101, and the light reflected from the signal recording surface is focused again by the objective lens and then incident on the optical detector for detection of the focus error signal and the tracking error signal.

The photodetector is composed of a plurality of photodetecting elements, and an electrical signal proportional to the amount of light obtained from each photodetecting element is output to the high frequency (RF) and servo error generating unit 103.

The high frequency and servo error generation unit 103 may generate a high frequency signal for data reproduction, a focus error (FE) signal for servo control, a tracking error (TE) signal, and the like from an electrical signal output from each photodetector of the photo detector. Detect.

The detected high frequency signal is output to the data decoder for reproduction, and servo error signals such as FE and TE are output to the servo controller 104.

The servo controller 104 processes the focus error (FE) signal to output a drive signal for focusing control to the focus servo driver 105, and processes the tracking error (TE) signal to signal the drive signal for tracking control. Output to the tracking servo driver 106.

At this time, the focus servo driver 105 moves the optical pickup 102 up and down by driving the focus actuator in the optical pickup 102 to follow the rotation and the vertical movement of the optical disk 101.

The tracking server driver 106 corrects the position of the beam by moving the objective lens of the optical pickup 102 in the radial direction by driving the focus actuator in the optical pickup 102 to track a predetermined track.

Here, the tracking control used for the DVD-based optical disc in the high frequency and servo error generator 103 and the servo controller 104 is generally a three-beam method, a push-pull method, and a differential phase detection. There are many ways such as DPD).

Among these, the push-pull method divides the photodetector of the photodetector detecting the reflected light from the optical disk in two tracks in the track direction, and then detects the tracking error signal from the light quantity balance of the two photodetectors. This utilizes the fact that the intensity distribution of light diffracted and reflected by the pit and then incident on the objective lens changes in accordance with the relative position change between the pit and the light spot.

If the shadow of the pit is evenly projected on the two photodetectors, the tracking error signal TE becomes zero, which is called tracking on (or on track). Conversely, a state in which the light error is shifted left and right from the track center and the tracking error signal TE has a + or-value is called tracking off (or off track).

At this time, the push-pull method has several conditions. One of them is called a wavelength of light, and when the depth of the pit is λ / 4, that is, when the diffraction by the pit is most effective and the modulation degree is maximized, the tracking error signal cannot be obtained by the push-pull method. That is, since the pattern when the pit depth is λ / 4 becomes a symmetrical pattern, a tracking error signal cannot be obtained from the photodetector divided into two.

On the other hand, the DPD method is an improvement on the push-pull method. Like the push-pull method, the DPD method uses the light intensity distribution according to the change in the relative position of the beam and the pit, but instead uses a quad split photo detector.

In the DPD method, a tracking error signal is generated by detecting a phase difference in a radial (radius) direction by receiving a light detector divided into four light intensity distributions.

Therefore, it is advantageous that the effect of the pit depth is small, for example, a tracking error signal is generated even at a pit depth of λ / 4, and even if the beam moves on the photodetector.

For example, if the photo detector is composed of four optical detection elements (PDA, PDB, PDC, PDD) divided into four, i.e., divided in the signal track direction and the radial direction of the optical disk as shown in FIG. The electrical signals a, b, c, and d are output in proportion to the amount of light obtained by the photodetectors PDA, PDB, PDC, and PDD.

At this time, the DPD method is a diagonal phase difference signal at the slice point of the high frequency signal, that is, (a +) based on the high frequency signals (a + b + c + d) obtained from the electrical signals a, b, c, and d output from the photodetector. The phase difference between the electrical signal of c) and the electrical signal of (b + d) is detected to generate a tracking error signal. In other words, the bipolar TE signal can be obtained by detecting the phase difference. As described above, the TE signal by the DPD method is generated using the phase difference in the radial direction detected by the objective lens passing through the pit on the track.

If the track is in the center of the beam as shown in Fig. 3B, the DPD signal is zero, and this value is always zero even if the disk rotates so that the relationship between the pit and the beam proceeds in the direction of the arrow. That is, no diagonal phase difference signal occurs. When the beam is displaced from the track as shown in Fig. 3 (a) and (c) and moved in the direction of the arrow with the rotation of the disc, the DPD signal becomes the sine wave output. Positive and negative shift In this case, since the relationship between + 90 ° and -90 ° is detected, a bipolar tracking error signal can be obtained by detecting a phase of the DPD signal at a slice point of the high frequency signal based on the high frequency signal. Here, the DPD signal means a tracking error signal obtained by the DPD method.

As described above, the tracking error signal is generated through the push-pull method and the DPD method, and the servo control performance is known to be superior to the DPD method than the push-pull method.

In the case of the DVD-ROM, since the pit depth is λ / 4, the tracking error signal cannot be detected by the push-pull method, so that the tracking error signal is obtained using the DPD method. In addition, the DVD-R or DVD-RW detects the tracking error signal by the DPD method when reproducing the area where the signal is recorded, and detects the tracking error signal by the push-pull method when recording the signal. In the case of DVD-RAM, only the prepit area detects the tracking error signal by the DPD method, and in other areas, the tracking error signal is detected by the push-pull method.

On the other hand, according to the conventional servo control method, if it is determined that the disc is capable of recording such as DVD-R, DVD-RW, etc. after determining the type of the loaded disc, the recording mode is first determined. And after initializing several calibrations, the tracking servo uses a push-pull method.

Therefore, even when the disc is used only in the regeneration mode, the loading time is delayed due to unnecessary initialization and the push-pull method, which is relatively inferior to the DPD method, is not used to provide satisfactory servo control performance. There was this.

The present invention has been proposed to solve such a conventional problem. When the type of the optical recording medium is determined, the recording mode and the playback mode are selectively predicted based on the presence or absence of data. By using the DPD method in tracking servo without performing the purpose, the purpose is to shorten the loading time and improve the servo control performance.

The servo control method of the optical recorder according to the present invention for achieving the above object comprises the steps of determining whether the type of the loaded optical record medium is a recordable type, and if the optical record medium is determined to be a recordable type. Confirming a data recording state of the optical recording medium, predicting and determining in a recording mode if data is not recorded on the optical recording medium, and predicting and determining in a reproduction mode if data is recorded on the optical recording medium; If it is determined that the recording mode is predicted, the servo control including the tracking servo by the push-pull method is performed after initializing the recording-related setting value, and when the prediction is determined to the reproduction mode, the servo including the tracking servo by the phase difference detection (DPD) method is performed. Performing control.

Hereinafter, exemplary embodiments will be described in detail with reference to the accompanying drawings. This embodiment allows for a better understanding of the objects, features and advantages of the present invention. However, the present invention is not limited to this embodiment.

4 is a flowchart showing a servo control process of the optical recorder according to the present invention.

As described above, the servo control method of the present invention includes the steps of determining the type of the loaded disc (S411 to S412), and when the disc is determined to be a recordable disc such as a DVD-R and a DVD-RW, the optical pickup is performed. Moving to the recording position to perform the focus servo, and after performing the tracking servo using the DPD method, checking whether the tracking servo control is normal (S421 to S424); and if the servo control is found to be abnormal, Performing a focus servo after initializing the recording-related setting value by predictive judgment and performing tracking servo by using the push-pull method (S431 to S434), and when the servo control is confirmed to be normal, the predictive judgment is performed by the regeneration mode. Performing the servo and performing the tracking servo by using the DPD method (S441 to S443), and the following command in the servo-on state after the tracking servo is performed. It waits for a command (S451).

An example in which the servo control method according to the present invention configured as described above is performed in the optical disc recording and reproducing apparatus of FIG. 1 will be described in detail below.

First, when the disk 101 is loaded, under the control of the servo controller 104, the optical pickup 102 scans the light beam onto the disk 101, collects the reflected light, and delivers the reflected light to the photo detector. Here, the servo control unit 104 determines the type of the disc 101 by using a known disc discrimination method based on the light detection result of the light detector (S411 to S412).

When the type of the disc 101 is determined to be a recordable disc such as a DVD-R or a DVD-RW, the servo control unit 104 checks whether data is recorded on the disc 101, and then the data is recorded on the disc 101. If it is in the recorded state, the prediction decision is made in the reproduction mode. If the data is not recorded on the disc 101, the prediction decision is made in the recording mode.

To this end, the servo control unit 104 performs the focus servo by moving the optical pickup 102 to the recording position of the disc 101, and checks whether the tracking servo control is normal after performing the tracking servo using the DPD method. do. At this time, it is preferable to move the optical pickup 102 to the middle portion of the disk 101 (S421 to S424).

Here, if the data is recorded at the recording position of the disk 101, the tracking servo is normally performed by the DPD method. If the data is not recorded at the recording position of the disk 101, the tracking servo is normally performed by the DPD method. I do not lose. This is due to the fact that the tracking servo by the push-pull method is normally performed when data is written.

Based on this servo control characteristic, the servo control unit 104 recognizes that the data is not recorded on the disc 101 when the tracking servo of step S423 is not normally performed, and predicts and determines the recording mode setting value, that is, After initializing the recording related registers and various calibrations, the focus servo is performed and the tracking servo is performed using the push-pull method (S431 to S434).

On the contrary, if the tracking servo of step S423 is normally performed, the servo control unit 104 recognizes that the data is recorded on the disc 101 and predicts the reproduction mode, performs the focus servo, and also performs the tracking servo using the DPD method. (S441 to S443).

Next, after performing the tracking servo in steps S434 and S443, the servo on state waits for a subsequent reproducing command or a recording command (S451).

Of course, if it is determined in step S412 that the type of the disc 101 is a disc for playback only, such as a DVD-ROM, the servo controller 104 determines that it is in a playback mode, and performs the processing of steps S441 to S451 described above.

On the other hand, even if it is determined in the playback mode in step S441, it will be natural to immediately change to the recording mode when a recording command is input from the outside. As described above, according to the present invention, when data is not recorded on the disc 101, the same processing process is performed by the recording mode as in the prior art, and when a subsequent playback command occurs while data is recorded on the disc 101, Unlike the prior art, the processing in the unnecessary recording mode is not performed. In addition, even when data is recorded on the disc 101, if a separate recording command is generated, the same process by the recording mode is performed as in the prior art. In step S421, the optical pickup 102 is transferred to the disc 101. Moving to the middle of is to minimize this mode prediction error.

In the foregoing description of the present invention, only one embodiment has been described, but it is obvious that the technology of the present invention can be easily modified by those skilled in the art. Such modified embodiments should be included in the technical spirit described in the claims of the present invention.

As described above, the present invention discriminates the recording mode and the reproducing mode based on the presence or absence of data after determining the type of the optical recording medium, and when the reproducing mode is predicted, the disc does not perform the recording related initialization. When used in mode, unnecessary initialization is not performed, so the loading time is reduced.

In addition, since the DPD method, which is relatively superior to the push-pull method during initial tracking servo, is used, the servo control performance is improved.

Claims (3)

Determining whether the type of the loaded optical record carrier is a recordable type; Checking a data recording state of the optical recording medium when the optical recording medium is determined to be a recordable type; Predicting and determining in a recording mode when the data is not recorded on the optical recording medium, and predicting and determining in a reproduction mode when the data is recorded on the optical recording medium; If it is determined that the recording mode is predicted, the servo control including the tracking servo by the push-pull method is performed after initializing the recording related setting value, and if the prediction mode is predicted to the reproduction mode, the tracking servo is performed by the phase difference detection (DPD) method. Performing servo control Servo control method of the optical record player comprising a. The method of claim 1, The servo control method includes moving the optical pickup to the recording position of the optical recording medium to confirm the data recording state, and performing the servo control including the tracking servo by the phase difference detection (DPD) method. Checks for normalness, And determining that the data is in the recorded state when the tracking servo control is confirmed to be normal, and determining that the data is in the unrecorded state when the tracking servo control is determined to be abnormal. The method of claim 2, And the optical pickup is moved to an intermediate portion of the optical record carrier.

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