KR20040082608A - Apparatus and method for controling tilt of optical record media - Google Patents

Abstract

PURPOSE: A tilt control device of an optical recording medium and a method thereof are provided to input an amplified/equalized RF signal to an A/D port of a microcomputer, to detect a tilt, and to optimally control the detected tilt according to a system, thereby stably and exactly detecting/controlling the tilt without a header within a disk. CONSTITUTION: An optical pickup(102) irradiates a light on an optical disk(101), and converts a reflected light into an electrical signal. An I/V(Current/Voltage) converter(103) converts the electrical signal into a voltage level. An RF signal generator(104) detects an RF signal from the voltage level signal, and amplifies/equalizes the RF signal. A comparator(105) compares the RF signal with a reference signal, and outputs compared results. A microcomputer(106) uses the outputted results as an interrupt signal, and inputs the RF signal to detect/control a tilt.

Description

Apparatus and method for controling tilt of optical record media}

The present invention relates to a tilt control apparatus and method for an optical recording medium.

In general, during data recording and reproducing on an optical recording medium, that is, an optical disk, laser light is incident on the opposite side of the reflective surface having a pit. Therefore, the pit appears as a projection when viewed from the laser incident side.

The pit has a width of 0.4 to 0.6 占 퐉, the length of one pit and the interval between the pit and the pit in a pattern of 3T to 11T for a compact disc (CD) and 3T to 14T for a digital multifunction disc (DVD). It is divided into patterns. Here, T means the length of one clock pulse, 3T means three clock pulses, and 11T corresponds to the length of 11 clock pulses.

In addition, the optical disk may be distorted during the injection and curing of the resin in the manufacturing process, thereby causing an eccentricity even when a central hole is drilled. Further, even if the disc track is accurately recorded in a spiral shape at a pitch of a predetermined standard, an eccentricity is generated because the center hole is varied. Thus, the disk rotates with eccentricity, so it is difficult for the central axis of the motor and the center of these tracks to completely coincide.

For this reason, since it is difficult to read exactly the signal of the desired track accurately, the CD and DVD system sets the standard for this deviation amount, and tracking servo is performed so that the light beam can always follow the desired track even if such an eccentricity occurs.

That is, the tracking servo generates an electric signal corresponding to the beam trace state and based on the signal, moves the objective lens or the optical pickup body in the radial direction to correct the position of the beam so that the track can be accurately followed.

On the other hand, when the beam deviates from the track, not only the eccentricity of the disc described above but also the case where the disc is inclined. This can occur due to mechanical problems such as errors when mounting the disk to the spindle motor. That is, the focusing and tracking do not exactly match vertically, but are distorted. The tilted state of the disc is called tilt.

This tilt was not a big problem for CDs with large track pitches because of their wide track pitch. Here, the tilt margin is an amount that can be corrected even if the disk is inclined to some extent. However, DVDs with narrow track pitch as optical applications such as optical discs have become larger and denser have a smaller radial tilt margin for jitter, so that even if a little tilt occurs, even if the disc is tilted slightly, the beam will pass to the side track. Detrack occurs, but tracking servo alone is not enough. That is, even if the beam is moved to the next track by tilt, if the beam is in the center of the track, the tracking servo can determine that the track is accurately tracked.

In this case, data cannot be read correctly during reproduction, and since the data cannot be recorded accurately on the track during recording, double distortion occurs when the recorded data is reproduced.

As such, the amount of tilt possessed by the system in the optical disc system is a very important factor in determining not only playback but also recording quality. Therefore, adjusting the tilt amount to fit the system is very important. For this reason, the amount of tilt is adjusted when the system is first created, but if the system is used continuously, it may be different from the initial amount of tilt due to the surrounding environment and the internal structure of the system. At this time, by adjusting the optimum amount of tilt for the system, it is possible to prevent the cause of deterioration in quality not only during recording but also during playback.

Conventionally, in the control of an optical disk system, the recording and reproduction of data is performed without performing the tilt control, or the tilt control is performed by installing a separate tilt control device. For example, there is a method of detecting a tilt of a disc by setting a tilt sensor for detecting tilt in the pickup, for example, a tilt-only light receiving element. In addition, in the DVD-RAM, a method of controlling the tilt by detecting a signal magnitude of a variable frequency oscillator (VFO) portion of a header signal has been proposed.

However, the method of controlling the tilt by using the above-described dedicated tilt control device or the VFO signal of the header has a problem in that the size of the set is increased and the price is increased while the precision of the tilt control is decreased. In addition, if there is no header in the disc without using the dedicated tilt control device, there is no way to detect the tilt, and thus tilt control cannot be performed.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide a tilt control apparatus and method for an optical recording medium for determining and controlling tilt from an RF waveform of a specific pattern.

1 is a block diagram of a configuration related to tilt control in the optical recording and reproducing apparatus according to the present invention;

FIG. 2 is a diagram of an exemplary embodiment in which a time point at which an RF signal crosses Vref is changed due to an ideal RF signal waveform and tilt of a specific pattern. FIG.

3 is a diagram of an exemplary embodiment of the present invention in which distortion of an RF waveform occurs due to an ideal RF waveform and a tilt of a specific pattern, thereby causing an RF error value.

4 is an operation flowchart illustrating a tilt control method of an optical recording medium according to an embodiment of the present invention.

Explanation of symbols for main parts of the drawings

101: optical disk 102: optical pickup

103: I / V converter 104: RF signal generator

105: comparator 106: micom

The tilt control apparatus of the optical recording medium according to the present invention for achieving the above object, an external comparator for comparing the amplified and equalized RF signal and the preset reference signal to the interrupt port of the microcomputer without having to implement a complicated separate system By detecting the tilt amount by adjusting the amplified and equalized RF signal to the microcomputer's A / D port and adjusting the tilt amount optimally for the system, the quality during recording as well as playback is prevented from being deteriorated due to tilt. It has its features.

In the tilt control method of the optical recording medium according to the present invention, determining the pattern of the RF signal to detect the tilt, and if there is no tilt, the next cross from the point of time when the RF signal of the determined pattern crosses the predetermined reference signal Storing the sampling time of the RF signal at this time; determining that the tilt needs to be adjusted; and when the RF signal of the specific pattern determined in the step is input, the RF signal is preset. Performing a count from crossing the reference signal to the reference value, sampling the RF signal at the time when the count ends, and sampling the sampled RF signal value and the pre-stored RF signal Comparing the values to detect the amount of tilt and to adjust the tilt.

Other objects, features and advantages of the present invention will become apparent from the following detailed description of embodiments taken in conjunction with the accompanying drawings.

Hereinafter, with reference to the accompanying drawings illustrating the configuration and operation of the embodiment of the present invention, the configuration and operation of the present invention shown in the drawings and described by it will be described as at least one embodiment, By the technical spirit of the present invention described above and its core configuration and operation is not limited.

FIG. 1 is a block diagram of a configuration related to tilt control of an optical recording and reproducing apparatus according to the present invention. For the optical pickup 102, the I / V (current / voltage) converter 103 for converting the electrical signal output from the optical pickup 102 to the voltage level, the output from the I / V converter 103 The RF signal generator 104 detects, amplifies, and equalizes an RF signal from a signal having a voltage level, and compares the EQ RF signal output from the RF signal generator 104 with the reference signal Vref and outputs the result. Comparator 105 and the output of the comparator 105 is used as an interrupt signal, and the microcomputer 106 for receiving the EQ RF signal to the A / D port to detect and adjust the amount of tilt.

The present invention configured as described above provides an external comparator 105 for comparing the amplified and equalized RF signal (EQ RF) and the reference signal (Vref) to the interrupt port of the microcomputer 106 without having to implement a complicated separate system, By receiving the amplified and equalized RF signal (EQ RF) through the A / D port of the microcomputer 106, the tilt amount is detected and the tilt amount is optimally adjusted according to the system. To prevent it.

That is, the EQ RF signal after the tilt has been adjusted to be suitable for the system as shown in FIG. 3 (that is, the ideal EQ RF signal indicated by the solid line in FIG. 3 and without tilt) and the EQ RF signal without the tilt adjusted ( That is, when comparing the dotted lines in FIG. 3, it may be determined that the eye pattern of the RF signal after the tilt is adjusted is clearly seen.

At this time, it can be determined internally that the tilt detection is accurate because a long pattern of the RF signal, for example, 11T or more of the patterns of the current RF signal is less shaken.

That is, the RF waveform of the ideal specific pattern (eg, 11T) intersects the reference signal Vref (eg, zero point) at a predetermined time interval as shown in FIG. 2. In this case, depending on the amount of tilt, that is, the more severe the tilt, the point at which the reference signal Vref intersects becomes much different from the ideal case without tilt.

In FIG. 3, it can be seen that a positive RF error value or a negative RF error value occurs according to the direction of the tilt when the tilt occurs.

Thus, in the present invention, first determine the pattern of the RF signal to detect the tilt. When the pattern is determined, the half cycle time of the RF signal of the pattern, i.e., the time from the time when the RF signal crosses the reference signal Vref to the next crossing time is stored as a reference value when the pattern is ideal. do.

Then, if it is necessary to adjust the tilt, if the RF signal of the determined pattern is input through the optical pickup 102, starting from the point when the RF signal crosses the reference signal (Vref) to be a reference value stored in advance The time until is counted to determine a point to A / D, for example a sampling point of the RF signal.

In this case, the comparator 105 is used to know the count start time, that is, the time when the RF signal crosses the reference signal Vref.

The comparator 105 compares the EQ RF signal output from the RF signal generator 104 with a preset reference signal Vref. For example, when the reference signal Vref is input to the inverting input terminal (-) of the comparator 105 and the output signal of the RF signal generator 104 is input to the non-inverting input terminal (+), as shown in FIG. When the signal output from the RF signal generator 104 is larger than the reference signal Vref, that is, when the RF signal crosses the reference signal Vref from downward to upward, the output value of the comparator 105 is equal to 0. Will be changed to 1. The microcomputer 106 receives an output signal of the comparator 105 as an interrupt terminal and uses the microcomputer 106 to determine whether to count the RF signal. In one embodiment, when the output of the comparator 105 is changed from 0 to 1, the microcomputer 106 starts counting, and when the count value reaches a pre-stored reference value, the microcomputer 106 determines the A / D point at this time. Sample the RF signal at point / D. According to the design of the comparator 105, the RF signal crosses the reference signal Vref from downward to upward, or may be determined to cross the reference signal Vref from upward to downward.

That is, the RF signal detected at the A / D point is input to the A / D converter of the microcomputer 106 through the A / D port, and the A / D converter digitizes the RF signal. This digitized value is referred to as an A / D value in the present invention for convenience of description.

At this time, the difference between the A / D value sampled at the A / D point and the A / D value when there is no tilt, that is, the RF error value, is the amount of tilt.

Therefore, the microcomputer 106 adjusts the tilt by driving the actuator of the optical pickup 102 in the direction in which the RF error value becomes the minimum, that is, the zero direction.

Meanwhile, in the present invention, the A / D point may be determined at two or more places. This is to confirm whether the input pattern is a pattern to be sampled. In FIG. 3, two A / D points are determined as an example.

For example, assuming that 11T is determined as the pattern of the RF signal to detect the tilt, if the pattern of the input RF signal is 11T, the A / D value of the RF signal detected at the first A / D point is more than a certain value. You will have Therefore, after setting a threshold value in consideration of a margin to a certain value, if the A / D value detected at the first A / D point is larger than the threshold value, the input RF signal pattern is determined to be 11T, It can also be judged as not 11T. For example, if the pattern of the input RF signal is 7T, the A / D value detected at the first A / D point will have a value smaller than the threshold value. As a result, it is possible to determine whether the pattern of the input RF signal is the pattern of the RF signal to measure the tilt.

4 is a flowchart illustrating the above-described tilt control method of the present invention. When the disc is inserted (step 401), the focus is initialized on and the tracking is initialized on (step 402). Then, it is checked whether the tilt adjustment is necessary (step 403).

Here, the tilt adjustment may be unconditional every time the disc is inserted, or may be determined by looking at the light beam reflected from the optical disc 101, which may be determined by the designer. If it is determined in step 403 that no tilt adjustment is necessary, the optical recording / reproducing apparatus performs normal playback or recording (step 408).

On the other hand, if it is determined in step 403 that the tilt needs to be adjusted, the microcomputer 106 checks whether the output signal of the comparator 105 changes from 0 to 1 (step 404). If the output signal of the comparator 105 changes from 0 to 1, the microcomputer 106 is interrupted and starts counting. The end point of the count is until a previously stored reference value corresponding to a half period of the RF signal in the absence of tilt is reached. The count end point is determined as an A / D point, and the EQ RF signal is detected and digitized at the A / D point (step 405). The tilt amount is detected by calculating a difference between the digitized, i.e., sampled A / D value and the A / D value when there is no tilt (step 406). Then, the tilt is adjusted by driving the actuator of the optical pickup 102 in the direction in which the tilt amount is minimum (step 407).

As described above, the tilt control device and method of the optical recording medium according to the present invention can stably, accurately and easily tilt even when there is no header in the disk without using a separate tilt control device even in a large-capacity, high-density optical disk. Can be detected and adjusted.

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the spirit of the present invention.

Therefore, the technical scope of the present invention should not be limited to the contents described in the embodiments, but should be defined by the claims.

Claims (4)

An apparatus for controlling tilt using an RF signal generated from an output signal of an optical pickup for irradiating light to an optical record carrier and converting reflected light into an electrical signal, A comparator comparing the RF signal with a reference signal and outputting a result; And After storing the reference value for the RF signal of a specific pattern in the absence of tilt, the result of the comparator and the reference value are used to determine the A / D point to sample the RF signal, and the RF signal sampled from the A / D point. And a controller which detects and adjusts the tilt from the tilt control device. The method of claim 1, wherein the control unit And counting the point when the count value becomes the reference value as the A / D point after starting the count according to the output of the comparator. The method of claim 1, wherein the control unit The tilt amount is detected by using a difference between the RF signal value sampled at the A / D point and the RF signal sampling value detected and stored when there is no tilt, and the tilt is adjusted in a direction in which the tilt amount is minimum. A tilt control device for an optical record carrier. A method of controlling tilt using an RF signal generated from an output signal of an optical pickup for irradiating light to an optical record carrier and converting reflected light into an electrical signal, Determining a pattern of an RF signal to detect tilt; If there is no tilt, storing the time from the time when the RF signal of the determined pattern intersects the predetermined reference signal to the next crossing time as a reference value, and storing the sampling value of the RF signal at this time; Determining that the tilt needs to be adjusted, and if an RF signal of a specific pattern determined in the step is input, performing a count from when the RF signal crosses a preset reference signal to a reference value; Sampling the RF signal at the point when the count ends in the step; And And detecting the tilt amount and adjusting the tilt by comparing the sampled RF signal value with a sampling value of the pre-stored RF signal.