KR100592498B1 - Optical Recording System for Detecting Frequency of Read Channel using Wobble Signal and Playback Method thereof - Google Patents

Abstract

The present invention relates to an optical recording apparatus for detecting a frequency of a read channel using a wobble signal, comprising: a pickup unit for detecting a wobble signal and a high frequency (RF) signal recorded on an optical recording medium; A frequency detector for generating a signal synchronized with the wobble signal detected by the pickup unit; A frequency information converter configured to calculate frequency information of a high frequency analog waveform in a read channel using a signal synchronized with the wobble signal; And a phase controller configured to control the phase of the high frequency signal by using the calculated frequency information of the high frequency analog waveform.

CD, DVD, Wobble, High Frequency, Frequency, Phase

Description

Optical Recording System for Detecting Frequency of Read Channel using Wobble Signal and Playback Method             

1 is a wobble signal structure diagram of a recording optical disc.

2 is a block diagram illustrating a frequency detection method and a phase locked loop using only high frequency waveforms.

3 is a block diagram of an optical recording apparatus for detecting a frequency of a read channel using a wobble signal according to an embodiment of the present invention.

4 is a block diagram of a pickup unit according to an embodiment of the present invention.

5 is a block diagram of a phase locked loop for a weave according to an embodiment of the present invention.

6 is a configuration diagram of a pulse-voltage generator according to an embodiment of the present invention.

7 is a flowchart illustrating a method of synchronizing a read channel of an optical recording apparatus using a wobble signal according to an embodiment of the present invention.

{Description of Major Symbols in Drawings}

301: Analog to Digital Converter for Wobble Signal

302: signal processing unit 303: phase locked loop for wobble

304: frequency information conversion unit

305: analog-to-digital converter for high frequency signals

306: high frequency phase detector 307: loop filter

308: high frequency voltage controlled oscillator 501: wobble phase detector

502: charge pump 503: loop filter

504: voltage controlled oscillator

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical recording apparatus for detecting a frequency of a read channel using a wobble signal and a reproduction method thereof, and more particularly to an optical disc for recording such as CD-R, DVD + -R / RW, BD-R / RW, etc. In the synchronization process corresponding to a high frequency (RF) analog signal, which is a process required for reproducing the stored bit data, the frequency component of the data input to the read channel is obtained by using the wobble signal which is already present in the recording disk as a whole. It's about how to pay.

Bit information divided into 0 and 1 is recorded on the surface of the optical disk, and the information is read as a high frequency analog waveform corresponding to the type of 0 and 1 due to the difference in reflectance of the laser light read from the pickup. The receiving unit of the optical disc player reads the generated high frequency analog waveform to reproduce the bit data recorded on the optical disc. In this process, the speed of bit data (referred to as data rate or channel rate) input to the receiver varies according to the speed at which the optical disk rotates, and in the receiver, a phase locked loop is usually used. Using loop 'PLL', sampling is performed according to the frequency and phase of input data (called synchronization) and bit data is reproduced.

However, since the input frequency of the data is not known at the beginning of the high frequency analog signal input, the data input frequency differs from the sampling frequency generated in the normal phase locked loop. In a phase-locked loop, reducing this frequency difference takes a long time (called pull-in time), and the longer the frequency difference, the longer the time. In addition, there is a pull-in range that can be overtaken by a normal phase-locked loop, depending on the characteristics of the normal phase-locked loop. Synchronization is not possible and playback of bit data is not possible. For this reason, a frequency detector ('FD') is usually implemented to reduce the difference between the sampling frequency and the input data frequency to help hunting phase locked loops. In general, an optical disk has a special signal (called a 'sink pattern') that distinguishes a bundle of signals. In the conventional case, a frequency detector detects a frequency using the length and interval of the sync pattern.

On the other hand, in the case of a recordable optical disc, a signal including information on a track is defined in order to express the information of the disc and the position where the bit data is to be recorded. Although they have different shapes depending on the type of optical disk, they are collectively referred to as wobble signals. The wobble signal is produced in a form in which the information of the disc and the location where the data is to be recorded when the disc is created is defined. When the user records the bit data on the optical disc, the wobble information is used to record the disc information necessary for recording. And determine the rotational speed and recording frequency of the disc and allow the data to be written to the designated location on the disc.

Since the wobble signal is promised and has a certain shape depending on the length of a certain amount of data to be stored, the wobble signal is also used to control the spindle motor when the recording disk is rotated. When recording bit data, data is recorded in accordance with the wobble signal on the disk in accordance with the position on the disk. Therefore, the bit data recorded on the recording optical disc is also synchronized with the wobble signal on the optical disc.

The conventional method of matching the input frequency and phase of data in a read channel for reproducing bit data has been to use only high frequency analog signals generated from bit data of optical discs. In this case, after a valid high frequency signal is input to the bit data, a method of detecting a frequency and synchronizing a phase is used. In a recordable disc, this method already controls the spindle motor by the wobble signal to detect the frequency and phase using only the high frequency analog signal input while the disc is rotating. In other words, by processing the wobble signal, only the high frequency analog signal is used again while the information on the speed of the disk rotation is known.

1 is a wobble signal structure diagram of a recording optical disc. The shape of the wobble varies according to the type of each optical disk. In this figure, the wobble of the DVD-R / RW is taken as an example. An optical disc for recording does not contain bit data when first manufactured. Therefore, in order to store the information of the disk and to specify the position when recording the bit data later, a signal form called a wobble is made when the disk is manufactured. Such wobble exists in a form in which the wobble is deformed to have a specific signal or frequency. That is, in the case of a normal read-only optical disc, the tracks have a linear shape, but in the case of a recording optical disc, the tracks have a sinusoidal shape or make a specific signal to store information necessary for recording the disc. . 1 is a view showing the shape of such a wobble as an example. An optical disc is divided into a track area in which a track divides a track between a groove area in which bit data is recorded and a groove area. In the case of a read-only optical disc, the shape of the groove and the land has a straight line when it is enlarged. However, in the case of an optical disc for recording, since the position necessary for recording and the information necessary for recording are needed on the disc and information for rotating or controlling the disc is required, the shape of the track has a sinusoidal shape as shown in FIG. It is intended to include data information in the form of having different frequency characteristics on these tracks or dividing grooves having specific signals between tracks. Depends on the type). Therefore, in the case of a recording disk, the wobble signal is used to control the disk, obtain information necessary for recording, and designate a location to store the bit data of the user.

2 illustrates a synchronization circuit required for bit reproduction using only a high frequency analog waveform in a read channel. To reproduce bit data from a high frequency analog waveform, the frequency and phase of the input data must match the frequency and phase of the sampling clock (this is called synchronization). This is accomplished by a phase locked loop (PLL), where there is usually a difference between the input data frequency and the sampling frequency. If this difference is large, it is impossible to synchronize or it takes a very long time to synchronize. Since the data cannot be played before synchronization, if the synchronization takes a long time, the data within the time cannot be played, and thus the performance of the read channel is degraded. Therefore, a circuit for detecting the frequency of the input data is added to the phase locked loop, and the phase control is performed after reducing the difference between the frequency of the input data and the sampling frequency through frequency detection.

2 is a block diagram of a typical frequency detection loop and a phase locked loop. First, the high frequency analog signal read from the pickup 200 is converted into digital data through the analog-to-digital converter 201. Since the frequency component of the input data is not known accurately at the beginning of the high frequency analog waveform input, the difference between the sampling frequency and the input data frequency is reduced through the frequency filter 202 and the loop filter 203 of the frequency detector. This frequency component is input to the voltage controlled oscillator 206 at a frequency offset. After the frequency detection, the phase difference is reduced through the phase lock loop. The phase locked loop consists of a phase detector, a loop filter 205 of the phase detector, and a voltage controlled oscillator 206 for generating a sampling clock or clock component.

As such, there is a problem in that a considerable time is required for frequency detection of a conventional high frequency signal.

An object of the present invention is to estimate the bit data input frequency of the input channel by using the wobble signal existing in the optical disc for recording such as CD-R / RW, DVD + -R / RW, BD-R / W as described above An optical recording device capable of fast and accurate synchronization in a read channel is provided.

Another object of the present invention is to provide a reproduction method of an optical recording apparatus for estimating the bit data input frequency of an input channel using a wobble signal.

In order to achieve the above object, an optical recording apparatus for detecting a frequency of a read channel using a wobble signal of the present invention includes: a pickup unit for detecting a wobble signal and a high frequency (RF) signal recorded on an optical recording medium; A frequency detector for generating a signal synchronized with the wobble signal detected by the pickup unit; A frequency information converter configured to calculate frequency information of a high frequency analog waveform in a read channel using a signal synchronized with the wobble signal; And a phase controller configured to control the phase of the high frequency signal by using the calculated frequency information of the high frequency analog waveform.

In the present invention, the frequency detector comprises: a wobble signal analog-to-digital converter for digitizing the analog wobble signal detected by the pickup unit; A signal processor which removes noise of the digitized wobble signal, passes only a valid signal, and extracts wobble data; And a phase locked loop for generating a signal synchronized with the extracted wobble data.

In the present invention, a method of reproducing a signal of an optical recording apparatus using a wobble signal to detect a frequency of a read channel includes a) detecting a wobble signal, controlling a rotation speed of a disc using the wobble signal, and performing a phase locked loop for wobble. Synchronizing a frequency and a phase of the signal with the detected wobble signal; b) the rotational speed of the disk and the frequency of the signal generated in the phase locked loop converge to a constant value; c) converting an output signal frequency of the converged phase locked loop into a read channel frequency and providing it to a phase controller; And d) synchronizing phase with input data and performing bit reproduction using the read channel frequency information.

In the present invention, the step b) is preferably repeated if the rotation speed of the disc and the frequency of the signal generated in the phase locked loop are not fixed to a constant value.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. In adding reference numerals to components of the following drawings, it is determined that the same components have the same reference numerals as much as possible even if displayed on different drawings, and it is determined that they may unnecessarily obscure the subject matter of the present invention. Detailed descriptions of well-known functions and configurations will be omitted.

3 is a block diagram of an optical recording apparatus for detecting a frequency of a read channel using a wobble signal according to an embodiment of the present invention.

In the above embodiment, the optical recording apparatus includes a pickup section 300, a frequency detector 30, a frequency information converter 304, and a phase controller 31.

The frequency detector 30 includes a wobble signal analog-to-digital converter 301, a signal processor 302, and a wobble signal phase locked loop 303, and the phase controller 31 includes a high frequency signal analog-to-digital converter 305. ), A phase detector 306, a loop filter 307, and a voltage controlled oscillator 308.

The embodiment schematically illustrates a system for generating a synchronized signal in the frequency detector 30 using a wobble signal and then synchronizing the sampling frequency and phase during bit reproduction using the wobble signal.

The optical recording apparatus includes a part of finding frequency information through a wobble and a part of finding frequency information of input data by using wobble frequency information in a read channel and synchronizing the input data with a sampling frequency. This configuration method is available for both analog and digital.

First, in an optical disc for recording, a wobble signal is processed to synchronize the wobble on the disc to obtain the rotational speed and various information of the disc. In this way, the rotation speed of the disk and the frequency information of the wobble can be obtained. This frequency information is then used when synchronizing the read channel to play the bit data on the disc, giving a frequency offset to the read channel's phase locked loop for fast synchronization.

Looking at the specific operation with reference to Figure 3 as follows.

The pick-up unit 300 includes various optical components, laser diodes, photo diodes, and the like, a fixing unit supporting them, and a driving unit for irradiating light and reading information. An objective lens is mounted on the driving unit to connect the fixing unit and the optical characteristic. The laser beam is irradiated to the information pit on the optical disk by optical means, and the focused light receives the light diffracted by the information pit on the optical disk and the presence or absence thereof, converts the light into an electrical signal, and at the same time, Accordingly, the information is recorded on the optical disc by the optical bundle which has been aberrant in this manner.

The pickup unit reads the wobble analog signal and the high frequency analog signal recorded on the optical disk. In the case of a recording optical disc, the wobble signal is first processed because the information of the disc is first obtained by the wobble and the disc is controlled.

The pickup may be divided into two parts. The focus of the pick-up portion and the object lens 407 on which optical components such as the laser diode 402, the photodiode 401, the collimator lens 406, the beam splitter 405, and the mirror 408 are mounted accurately tracks the information. This is the part of the actuator that drives it. 4 shows an example of a pickup section for a DVD-ROM. In the case of a pickup unit for a DVD-ROM, two laser diodes 402 are often used to maintain compatibility with an existing CD-ROM. In FIG. 4, the light path in the case of reproducing CD is parallel while the laser having a wavelength of 780 nm emitted from the laser diode 401 passes through the beam splitter 405 and then passes through the collimator lens 406 through the half mirror 404. After being converted to light, it is reflected through the mirror 408 to enter the object lens 407 to maintain focus on the recording surface of the disk. The laser light reflected from the disk passes through the aberration corrector 403 which corrects the aberration along the reverse path of incidence to generate a signal to the photodiode 401. When the DVD is reproduced, a laser in which the photodiode 401 and the laser diode 402 are integrated is emitted. The emitted laser reads the disk information along the path of the beam splitter 405 → half mirror 404 → collimator lens 406 → mirror 408 → object lens 407 and along the reverse path of the HOE 409. It is preferable to form an image on the photodiode 401 included in the readout signal.

The wobble signal detected by the pickup unit 300 is first digitized through an analog-to-digital converter for the wobble signal. The digitized wobble signal is removed with noise through the signal processor 301. The signal processor 302 passes only a valid signal or extracts a digitized wobble signal (hereinafter referred to as 'wobble data'). That is, when signals of various components overlap during the signal conversion process, only data on the wobble signal is extracted. The wobble phase locked loop 303 then uses the wobble data to generate a signal synchronized with the wobble signal, which is then used for data recording or disc control.

5 is a block diagram of a phase locked loop for a wobble for generating a signal synchronized with a wobble signal according to an embodiment of the present invention.

In this embodiment, the wobble phase locked loop includes a wobble phase detector 501, a charge pump 502, a loop filter 503 and a wobble voltage controlled oscillator 504.

The above embodiment shows a method in which the optical recording device generates a signal synchronized with the wobble signal.

Referring to FIG. 5, the wobble data which has been digitally converted and processed is first input to the phase detector 501. The wobble data is pulse-shaped data, and the difference between the input wobble data and the previously input and feedback wobble data is input to the charge pump 502 to adjust the output voltage.

The charge pump 502 is configured to push and pull a specific amount of charge according to the pulse signal of the wobble phase detector 501. FIG. 6 illustrates an embodiment of the charge pump 502, in which the amount of charge output is changed according to the pulse width, and thus the amount of charge corresponding to the difference between the two signals is pushed and pulled. In addition, since the voltage must be raised or lowered according to the difference between the two signals in the reference voltage value, two branching operations are performed. If the charge is needed to raise the voltage, it is pushed out. If the charge is subtracted to lower the voltage, the charge is pulled out.

That is, according to the sign of the pulse value, the charge pump pushes out the amount of charge corresponding to the pulse width to accumulate or reduce the charge in the capacitor of the loop filter 503 to adjust the voltage to the output voltage.

The loop filter 502 basically has a low pass filter structure and serves two roles. First, capacitors arranged in parallel accumulate and release charges that are pushed and pulled from the charge pump. As described above, since the charge pump 502 pushes or takes away the charges depending on the output of the phase detector 501, the amount of charge accumulated changes. The change in the amount of charge supplied to the capacitor serves to proportionally change the voltage of the control terminal portion of the wobble voltage controlled oscillator 504. That is, the loop filter 503 varies the control terminal input voltage of the wobble voltage controlled oscillator 504. In addition, since no frequency signal other than the signal near the DC is required at all, other frequency sources are eliminated.

The wobble voltage controlled oscillator 504 changes the frequency of an output signal output in accordance with the voltage charged in the capacitor of the loop filter 503. The frequency is preferably proportional to the magnitude of the input voltage.

The output signal thus output is compared with the wobble data and the difference is repeated by the above-described loop, so that the wobble phase locked loop 203 outputs a signal having the same frequency as the wobble signal.

The process of processing the wobble signal and generating the sync signal has been described above, but this may be different for each optical recording device. An important content is that the rotation speed of the disc is determined through the wobble having position information on the disc. Wobble can be used to find the frequency component of the high frequency input data.

The frequency information converter 304 calculates the frequency information of the high frequency analog waveform in the read channel by using the frequency component of the wobble output from the wobble phase locked loop. Since the wobble of the recording disk and the bit data to be recorded are synchronized, the frequency component of the read channel corresponds linearly to the frequency component of the wobble, and the calculated frequency component is the frequency offset of the phase control section 31 of the read channel. Is provided.

That is, since the frequency information of the read channel can be obtained through the wobble, it is possible to directly control the phase locked loop process using the frequency information. The phase controller of FIG. 3 is the same as the phase detector 306, the loop filter 307, and the voltage controlled oscillator 308 as shown in FIG. 2, and has a function similar to that of the frequency detector of the wobble signal. However, by using the frequency detected by the wobble signal as the initial offset, the sampling signal for detecting the bit data can be synchronized in a short time.

 7 is a flowchart illustrating a method of synchronizing a read channel of an optical recording apparatus using a wobble signal according to an embodiment of the present invention.

Steps 401 and 402 are processes for synchronizing a phase locked loop for a wobble using a wobble signal, wherein the pickup unit detects a wobble signal formed on a groove in the optical recording medium. The detected wobble signal generates a control signal of the spindle motor and a gate signal for detecting the land prepit. The spindle speed is first controlled by using the detected wobble signal to determine the rotational speed of the optical disk. In addition, the input wobble signal is digitally converted into a pulse signal. The wobble data converted into the pulse signal is input to the wobble phase locked loop while noise is removed through predetermined signal processing.

The phase locked loop for the wobble generates a signal having the same frequency as the input wobble data. The wobble data is compared with a previously input and output signal, and the difference in the signal is a charge pump to a predetermined value. Is entered. The charge pump adjusts the charge amount of the capacitor in the loop filter according to the pulse value, and the charge amount of the capacitor becomes an input value of the wobble voltage controlled oscillator and outputs a signal having a predetermined frequency. This process is repeated until the frequency of the signal output from the phase lock loop for wobble is synchronized with the frequency of the wobble signal. When the frequency of the wobble signal and the phase locked loop are synchronized, the phase locked loop constantly outputs a signal having the same frequency source as the wobble signal. Of course, if the wobble signal is changed, the phase locked loop is changed to the same frequency source as the changed wobble signal.

Step 403 is a process of converting the wobble signal frequency and converting the frequency of the signal generated in synchronization with the frequency of the detected wobble signal to a read channel frequency. Since the frequency component of the read channel corresponds linearly to the frequency component of the wobble, the frequency of the synchronized signal is converted for each optical recording device. The conversion method is preferably one-to-one correspondence conversion using a conversion table.

Step 404 is a phase detection process, in which a phase of a high frequency signal is detected using the detected frequency information. The frequency information converted in step 403 is input as an initial offset value of the phase controller.

In operation 405, the phase controller of the read channel detects whether phases are synchronized. The phase of the high frequency signal is detected by offsetting the frequency value detected from the wobble signal. When the phase of the high frequency signal converges to a predetermined value, the phase controller synchronizes the phase of the converged predetermined phase value with the input data to perform bit reproduction.

By this method, frequency information is already received in a stable state of the wobble signal and the spindle motor, and the read channel is used, thereby saving time for detecting the frequency using only a high frequency analog waveform. Therefore, the efficiency of bit reproduction capability of the read channel can be improved by saving the frequency detection time when reading the recording area immediately after the unrecorded area in the recording optical disk.

As described above, the present invention has been described with reference to the preferred embodiments, but those skilled in the art can variously modify and modify the present invention without departing from the spirit and scope of the present invention as set forth in the claims below. It will be appreciated that it can be changed.

As described above, according to the present invention, a read channel is obtained by estimating the bit data input frequency of an input channel using a wobble signal existing in an optical disc for recording such as CD-R, DVD + -R / RW, and BD-R / W. Synchronization at can be fast and accurate.

In addition, this algorithm can be implemented simply because it is less affected by the type of optical disc for recording.

Claims (4)

An optical recording apparatus comprising: a pickup section for detecting a wobble signal and a high frequency (RF) signal recorded on an optical recording medium; A frequency detector for generating a signal synchronized with the wobble signal detected by the pickup unit; A frequency information converter configured to calculate frequency information of a high frequency analog waveform in a read channel using a signal synchronized with the wobble signal; And a phase controller configured to control a phase of the high frequency signal by using the calculated frequency information of the high frequency analog waveform. 2. The apparatus of claim 1, wherein the frequency detector comprises: an analog-to-digital converter for a wobble signal for digitizing the analog wobble signal detected by the pickup unit; A signal processor which removes noise of the digitized wobble signal, passes only a valid signal, and extracts wobble data; And a phase locked loop for generating a signal synchronized with the extracted wobble data. a) detecting a wobble signal, controlling a rotation speed of the disc using the wobble signal, and synchronizing a frequency and a phase of a wobble phase locked loop with the detected wobble signal; b) the rotational speed of the disk and the frequency of the signal generated in the phase locked loop converge to a constant value; c) converting an output signal frequency of the converged phase locked loop into a read channel frequency and providing it to a phase controller; And and d) detecting a frequency of a read channel by using a wobble signal including synchronizing a phase with input data and performing bit reproduction using the read channel frequency information. 4. The wobble signal according to claim 3, wherein the step b) is repeated if the rotation speed of the disk and the frequency of the signal generated in the phase locked loop are not fixed to a constant value. And a signal reproducing method of the optical recording device for detecting the frequency of the read channel.

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