KR100698907B1 - Method for detecting and compensating tilt angle of optical disc reproducing and recording apparatus - Google Patents

Abstract

The present invention relates to a tilt measurement and compensation method of an optical disc recording / reproducing apparatus. More particularly, the present invention relates to a tilt of an optical disc using a tilt value corresponding to an optimal jitter value and a FOD level at a predetermined position of the disc. The present invention relates to a tilt measurement and compensation method of an optical recording and reproducing apparatus which measures and compensates a tilt value considering a skew of an optical pickup unit. A tilt measuring and compensating method of an optical reproducing and recording apparatus, the method comprising the steps of: (a) measuring a tilt value (T0) using jitter in a data recording area (hereinafter referred to as reference position) of an optical disc inner circumference; (b) measuring a tilt value according to the shape of the optical disc by using FOD levels at a plurality of points of the optical disc including the reference position; (c) measuring and compensating the tilt of the optical disc using the difference Ts of the tilt values of the reference positions measured in steps (a) and (b).

Description

Method for detecting and compensating tilt angle of optical disc reproducing and recording apparatus

1 is a diagram showing a tilt measurement and compensation method of a conventional optical disc recording / reproducing apparatus.
2 is a block diagram of an optical disc recording / reproducing apparatus according to an embodiment of the present invention.

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3 is a view showing a tilt measurement and compensation method of an optical disc recording / playback apparatus according to the present invention;

4 is a flowchart of a tilt measurement and compensation method of an optical disc recording / playback apparatus according to the present invention;

* Description of symbols on the main parts of the drawings *

110: optical pickup device 120: spindle motor

130: playback signal detector 140: jitter detector

150: control unit 160: tilt drive control unit

170: focus servo controller

The present invention relates to an optical disc recording / reproducing apparatus, and more particularly to a method for measuring and compensating tilt of an optical disc.

In general, an optical pickup in an optical disc recording / reproducing apparatus irradiates a laser onto an optical disc, detects the intensity of reflected light, and reads data recorded on the surface of the optical disc. For accurate reading of the data, the optical pickup should be arranged perpendicular to the surface of the optical disc.

However, due to manufacturing process problems, the optical disc is not ideally flat and the optical pickup is not installed to be exactly perpendicular to the optical disc. The degree to which the optical disc and the optical pickup deviate from the vertical is called a tilt value, and the optical pickup is driven in the forward or reverse direction by using a driving device so that the optical disk is perpendicular to the surface of the optical disc by compensating the tilt value.

Whether or not the optical pickup and the optical disc are arranged vertically can also be seen as a jitter value indicating the accuracy of data read from the optical pickup. Therefore, it is ideal to adjust the optical pickup with the tilt value where the jitter value of the input data is optimal (smaller value means higher accuracy) while swinging the optical pickup in the forward / reverse direction, but this jitter value is the area where the data is recorded. Measurements can only be made at, so there is a limit to using jitter to compensate for tilt values.

1 is a diagram illustrating a tilt measurement and compensation method of a conventional optical disc recording / reproducing apparatus. In the related art, a tilt value optimal for jitter is measured while swinging an optical pickup forward and backward in the innermost circumference of an optical disc in which data is always recorded. (①) Measure the FOD level (level of focus drive signal FOD) at a plurality of points on the optical disc (②), and convert the difference to the tilt value (③) and consider the tilt value obtained using jitter. The tilt value was compensated. However, the tilt value can be distinguished from the bending of the optical disc itself and the misalignment of the optical pickup, whereas the tilt value using jitter includes both without distinction. Therefore, the conventional tilt compensation method of compensating the tilt value of the entire optical disc by using the tilt value caused by the jitter has a problem that the tilt compensation is severe when the optical pickup is installed incorrectly or the tilt of the optical disc is large.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and an object of the present invention is to optically reproduce the light pickup of the optical pickup to the optical disk as much as possible in consideration of both the degree of warpage of the optical disk and the degree of warpage of the deck (optical pickup). And a tilt measurement and compensation method of the recording apparatus.

The tilt measurement and compensation method of the optical reproducing and recording apparatus of the present invention for achieving the above object is a tilt measurement and compensation method of the optical reproducing and recording apparatus,

(a) Measuring the tilt value T0 using jitter in the data recording area (hereinafter referred to as reference position) of the inner circumference of the optical disc

(b) measuring a tilt value according to the shape of the optical disk by using FOD levels at a plurality of points of the optical disk including the reference position;

(c) The tilt of the optical disc is measured and compensated using the difference Ts of the tilt values of the reference positions measured in the above steps (a) and (b).

The reference position in step (a) is characterized in that the control data area in which data is always recorded.

In addition, step (b),

(b1) measuring the FOD level at a plurality of points of the optical disc including the reference position;

(b2) obtaining a FOD function of the entire optical disc using the measured plurality of FOD levels;

(b3) estimating the FOD level of the center of the optical disk using the FOD function;

and (b4) calculating the tilt value T0 'of the reference position by using the estimated FOD level.

In addition, the FOD function of (b2) is characterized in that the second function.

Also, in step (c),

(c1) measuring a tilt value of each point by using a difference of FOD levels between a plurality of points of the optical disc

and (c2) compensating the tilt of the corresponding point by adding the Ts to the tilt value of each point.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

2 is a block diagram of an optical recording and reproducing apparatus according to an embodiment of the present invention. As shown in FIG. 1, the optical disc recording / reproducing apparatus includes an optical disc 100 and an optical pickup 110 for irradiating a laser onto the optical disc to read data recorded on the optical disc and a spindle motor 120 for rotating the optical disc. And a tilt to compensate for the tilt value with the playback signal detector 130 for detecting data from the optical signal read out from the optical pickup 110, and the jitter detector 140 for detecting the jitter value indicating the degree of degradation of the playback signal. The tilt servo controller 160 for controlling the drive and the focus servo controller 170 and the spindle motor 120 and the focus servo controller for controlling the focus servo such that the optical pickup maintains a constant distance with the optical disk and the laser focuses on the track. And a controller 150 for controlling the focusing of the optical pickup by sending the FOD to the optical pickup and controlling the tilt compensation of the tilt driving controller 160 based on the jitter value and the FOD level.

When the tilt measurement and compensation method of the present invention is described with reference to Figs. 1 and 3, the data recording area of the inner circumference of the optical disc (hereinafter referred to as a reference position) will be described first to measure the tilt value at which jitter is optimal. The optical pickup 110 is moved to). A control data area exists on the innermost circumference of the optical disc, and data indicating the type of the disc (DVD-R, DVD-RW, CD-R, etc.) and the state of the disc is recorded. While reading this data, the optical pickup 110 is moved in stages up to the limit in the (a) or (b) direction. This moves to the limit and initializes the position of the optical pickup 110. The data of the optical disc detected while swinging the optical pickup 110 is detected through the reproduction signal detector 130. The jitter detector 140 receiving the detected reproduction signal detects the jitter indicating the degree of degradation of the data and transmits the jitter to the controller 150. The controller 150 checks the jitter value and measures the optimal tilt value T0 through the angle of the optical pickup 110 that minimizes jitter. (①) This T0 is not only the degree of warpage of the optical disk but also a deck (optical light). The degree of warpage of the pickup 110 (including the pickup 110) is also a value indicating the angle of the optical pickup 110 when the jitter is optimal.

After measuring T0, the controller 150 sequentially moves the optical pickup 110 from the inner circumference to the outer circumference of the optical disk, including the reference position, for focusing by the fogger servo controller 170 according to the disc tracking. Detects the FOD level transmitted to the optical pickup 110. (②)

는 이러한 FOD레벨의 함수를 2차함수로 상정한 것을 나타낸 것이다.The FOD level is a signal sent to maintain a constant distance from the disk for focusing and can be converted into a distance difference between the top and bottom of the disc at each point from the difference in size. Therefore, it can be said that the function of the FOD level approximates the shape of the optical disc. The function associated with the FOD level of the whole disk can be assumed through the FOD level {F1-Fn} of each point {P1-Pn} detected previously, and the function can be uniquely determined through {F1-Fn}. For convenience of explanation, the reference position is P1. In general, the optical disc 100 has a shape such as a linear function such as a straight line or a curved shape such as a third function. Therefore, the quadratic function is appropriate for the FOD level function. 3

Shows that the function of the FOD level is assumed to be a quadratic function.

If the FOD level function is defined through {F1 ~ Fn}, the y-intercept c of the function can be estimated as the FOD level (F0) at the center of the optical disk.

Also, the tilt values {T1 to Tn} of each point are measured as shown in ④ of FIG. 3 by using the difference between the tilt values {T1 to Tn} of each point and a predetermined distance of moving the optical pickup 110 to each point. can do. The T1 of P1 can be measured relatively accurately using the estimated F0 and the measured F1 in the center.

When the difference Ts between T0 and T1 due to jitter at the reference position P1 obtained above is obtained, this value Ts is the degree of warp of the optical disk in consideration of the degree of warp of the deck. That is, the degree of warpage of the optical disc on the basis of the deck is obtained. Therefore, when Ts is added to the tilt values {T2 to Tn} of each point, the degree of warpage at each point is accurately measured. The controller 150 instructs the tilt driving control unit 160 such tilt compensation, and the tilt driving control unit 160 controls the optical pickup 110 to compensate for the tilt.

4 is a flowchart of a tilt measurement and compensation method of the optical disc recording / reproducing apparatus according to the present invention. First, the optical pickup 110 is measured at a reference position, which is a data recording area of the inner circumference of the disk, and the tilt value T0 of which jitter is optimal is measured. (Step S410) The optical pickup 110 is moved from the inner circumference of the disk to the outer circumference. Measure the FOD level {F1 ~ Fn} at each point {P1 ~ Pn} while moving sequentially by a certain distance (step S420). Using the measured {F1 ~ Fn} to obtain a function of the FOD level The FOD level of the disk center is estimated using the function (step S430). The tilt value T1 at P1 is measured using the previously estimated F0 and F1 of P1. (Step S440) At the reference position P1 Calculate the difference Ts between T0 due to jitter and T1 using the FOD level. This Ts is the degree of warpage of the optical disc based on the deck. (S450) The tilt value of each point is obtained by using the difference in the FOD level between the points and the predetermined distance that the optical pickup 110 sequentially moves. The tilt value of each point is compensated using {T2 ~ Tn} and Ts (step S470).

The tilt compensation at points other than the measured tilt value to be compensated for may be compensated relatively accurately by various methods such as linear interpolation.

As described in detail above, the present invention estimates the FOD level of the center of the disc using the FOD level measured at each point and compares it with the tilt value (T0) due to jitter to determine the deflection of the disc and the deflection of the deck. By distinguishing and compensating, the disk affix angle of the laser can be optimized more accurately.

In addition, there is an effect that the quality and stability of the recording / playback can be effectively secured in the optical disk recording / playback device of which the wavelength used is shortened.

Claims (5)

In the tilt measurement and compensation method of the optical reproduction and recording device, (a) measuring the tilt value T0 by using jitter at a reference position, which is a data recording area of the optical disc inner circumference; (b) measuring a tilt value according to the shape of the optical disc by using FOD levels at a plurality of points of the optical disc including the reference position; and (c) compensating the tilt of the optical disc by using the difference Ts of the tilt values of the reference positions measured in steps (a) and (b). The method of claim 1, and a reference position of step (a) is a control data area in which data is always recorded. The method of claim 1, wherein step (b) comprises: (b1) measuring FOD levels at a plurality of points of the optical disc including the reference position; (b2) obtaining a FOD function of the entire optical disc using the measured plurality of FOD levels; (b3) estimating the FOD level at the center of the optical disc using the FOD function; and (b4) calculating the tilt value T0 'of the reference position using the estimated FOD level. The method of claim 3, wherein A tilt measuring and compensating method for an optical reproducing and recording apparatus, characterized in that the FOD function of the entire optical disc of (b2) is a secondary function. The method of claim 1, wherein step (c) (c1) measuring a tilt value of each point by using a difference of FOD levels between a plurality of points of the optical disc; and (c2) compensating the tilt of the corresponding point by adding the Ts to the tilt value of each point.

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