JPH0727656B2 - Optical disk eccentricity phase detector - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an eccentricity phase detection device for an optical disc used for recording / reproducing information or the like.

2. Description of the Related Art In recent years, in tracking control for causing an optical head of an optical disk to follow a desired track, eccentricity correction has been performed to cancel out the eccentricity caused by the eccentricity of the disk itself or the center deviation at the time of installation in a rotating system. It was

A conventional eccentric phase detection device for an optical disc will be described below. FIG. 4 is a block diagram showing the configuration of a conventional optical disc eccentricity phase detector, and FIG. 5 is a waveform diagram at each store.
FIG. 6 is a schematic flowchart of the operation.

In FIG. 4, 1 is an optical disk, 2 is an optical head for recording and reproducing information on the optical disk 1, and 3 is the optical disk 1.
A spindle motor for rotating the optical disc 1 at a predetermined speed, 4 is a pulse generating means for generating a pulse for each rotation in synchronization with the rotation of the spindle motor 3, and 5 is a track of the optical spot 1 of a light spot detected by the optical head 2. Of the rectangular wave signal which is the output of the waveform shaping means 5 is an output of the waveform shaping means 5.
A rectangular wave width detecting means composed of a clock generating circuit for detecting the level width and the L level width, a counter latch circuit, etc., and a storage means 7 for sequentially storing the output of the rectangular wave width detecting means 6 for one rotation of the optical disc 1. , 8 are storage means 7
First computing means for finding the maximum or minimum rectangular wave width from the group of rectangular wave widths stored in 10, from the pulse output from the pulse generating means 4 to the maximum rectangular wave width found by the first computing means 8. Is a third arithmetic circuit for calculating the phase of the eccentricity from the width of the square wave and the total rectangular wave width stored in the storage means 7.

In FIG. 5, d is the waveform of the tracking error signal indicating the deviation of the light spot output from the optical head 2 from the track, e is the waveform of the output signal of the waveform shaping means 5, and f is the waveform of the tracking error signal.
Is the waveform of the output signal of the pulse generating means 4 synchronized with the rotation of the spindle motor 3, and the second pulse is output after the optical disk 1 makes one rotation after the first pulse is output. g is a waveform representing the amount of eccentricity, and the phase of the eccentricity detected (the width up to the intermediate value of the maximum rectangular wave width W (M)) with respect to the true phase θ of the eccentricity with respect to the first pulse is T (M). , The difference is δ.

The operation of the conventional optical disk eccentricity phase detecting device configured as described above will be described below with reference to the schematic flowchart of FIG.

First, a linear motor (not shown) for moving the optical head 2 is fixed, and the first signal is output from the output signal f of the pulse generating means 4.
Each pulse width W (n) of the output signal e obtained by shaping the output signal d of the optical head 2 into a rectangular wave by the waveform shaping means 5 until the second pulse is detected (step 12). Are detected by the rectangular wave width detection means 6 and are sequentially stored in the storage means 7 (step 13).

Next, the maximum (or minimum) rectangular wave width W is selected from the rectangular wave width group stored in the storage means 7 by the first computing means 8.
(M) is calculated (step 14).

Next, the third calculation means 10 causes the width T (M) from the first pulse to the maximum rectangular wave width, that is, T (M) = W (1) + W (2) + ... + W (M-1). ) + W (M) / 2 is calculated (step 16).

Next, the width from the first pulse to the second pulse, that is, the total sum T of the rectangular wave width groups stored in the storage means 7.
(N), T (N) = W (1) + W (2) + ... + W (N) (N is the total number) is calculated (step 17).

Next, the phase T T of the eccentricity T T = 360 ° × T (M) / T (N) is calculated from the calculated width T (M) up to the maximum rectangular wave width and the total sum T (N) of the rectangular wave widths (step 18)

However, in the above-described conventional configuration, the tracking error signal d is shaped into the rectangular wave signal e, and the phase of the eccentricity is calculated by calculating the maximum rectangular wave width. In the vicinity of the maximum rectangular wave width, a deviation occurs between the phase of the eccentricity and the obtained phase due to the disturbance of the waveform, and sufficient eccentricity correction cannot be performed. There is a problem that it is difficult to detect the minimum rectangular wave width.

The present invention solves the above-mentioned conventional problems, and an object of the present invention is to provide an eccentricity phase detection device for an optical disc, which can obtain a sufficiently accurate eccentricity phase.

Means for Solving the Problems In order to achieve this object, an eccentricity phase detection device for an optical disc of the present invention detects a maximum rectangular wave width from a stored rectangular wave width, and at least before and after the maximum rectangular wave width. Two
The configuration is such that an intermediate value of width groups up to the rectangular wave width stored before and after one or more is calculated, and the phase of eccentricity is calculated from the intermediate value and the stored total rectangular wave width.

Action With this configuration, it is possible to improve the phase detection shift of the eccentricity due to the disturbance of the tracking error signal near the maximum rectangular wave width.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic block diagram of an optical disk eccentricity phase detecting apparatus according to an embodiment of the present invention, FIG. 2 is a waveform diagram at each point, and FIG. 3 is a schematic flowchart of the operation.

In FIG. 1, reference numeral 9 is a second arithmetic means for obtaining widths up to at least two rectangular wave widths before and after centering on the maximum rectangular wave width obtained by the first arithmetic means 8 and for obtaining an intermediate value thereof. Is. 1 is an optical disk, 2 is an optical head, 3 is a spindle motor, 4 is pulse generation means, 5 is waveform shaping means, 6 is rectangular wave width detection means, 7 is storage means, and 8 is first.
And 10 is a third arithmetic means, which has the same configuration as the conventional example.

In FIG. 2, a is a waveform of a tracking error signal that represents the deviation of the light spot output from the optical head 2 from the track, and is waveform-shaped into a rectangular wave signal b after being compared at the slice level indicated by the alternate long and short dash line. . W
(M) is the maximum rectangular wave width of the rectangular wave signal b and W (M-
1) represents the width of the immediately preceding rectangular wave, and S represents the width up to 10 rectangular waves before and after the maximum rectangular wave width W (M). c
Is the waveform of the output signal of the pulse generating means 4, and one pulse is output for one rotation in synchronization with the rotation of the spindle motor 3, and the period from the first pulse to the second pulse is one rotation of the optical disc 1. T (L) is the S from the first pulse
Of the true eccentricity θ and T (L).

The operation of the optical disk eccentricity phase detecting apparatus of the present embodiment configured as described above will be described below with reference to the schematic flowchart of FIG.

First, a linear motor (not shown) for moving the optical head 2 is fixed, and the first pulse is detected from the output signal c output from the pulse generating means 4 one pulse per rotation according to the rotation of the optical disc 1 ( Step 11) Until the optical disc 1 rotates, that is, until the second pulse is detected (step 12), each width W of the output signal b obtained by shaping the output signal a of the optical head 2 into a rectangular wave by the waveform shaping means 5
(N) is detected by the rectangular wave width detection means 6, and the storage means 7
Are stored in order (step 13).

Next, when the second pulse is detected, the maximum rectangular wave width W (M) is obtained from the rectangular wave width group stored in the storage means 7 by the first calculating means 8 (step 14).

Next, the second calculating means 9 causes the maximum rectangular wave width W
An intermediate value between at least two, for example, the rectangular wave width W (M-10) stored ten times before and after the same number ten times, the rectangular wave width W (M + 10) stored after (M) is obtained ( Step 15).

Next, the width (that is, the width up to the maximum rectangular wave width) T (L) from the first pulse to the intermediate value is calculated by the third calculation means 10, that is, T (L) = W (1) + W (2) + ... + W (M-11) + {W (M-10) + ... + W (M) t ... + W (M + 10)} / 2 is calculated (step 16).

Next, the width from the first pulse to the second pulse, that is, the total sum T of the rectangular wave width groups stored in the storage means 7.
(N) T (N) = W (1) + W (2) + ... + W (N) (where N is the total number) is calculated (step 17).

Next, the width T from the obtained first pulse to the intermediate value
The eccentric phase T T = 360 ° × T (L) / T (N) is obtained from (L) and the total sum T (N) of the rectangular wave width group (step 18).

As described above, according to the present embodiment, an intermediate value from the rectangular wave widths stored at least two before and after the maximum rectangular wave width to the rectangular wave widths stored after the same number is calculated, and the intermediate value is calculated as the intermediate value. By configuring the eccentricity phase from the stored sum of rectangular wave widths, the center value of the maximum rectangular wave width can be calculated as the average of the rectangular wave widths before and after it, and the disturbance of the tracking error signal near the maximum rectangular wave width can be obtained. It is possible to improve the phase detection shift due to eccentricity.

In this embodiment, the case where all of the solid lines of the tracking error signal a are larger than the slice level has been described, but the rectangular wave width is bordered by the maximum width portion of the tracking error signal a. Since the rectangular wave widths before and after the same number are almost equal, even if the level of the maximum width part is lower than the slice level and cannot be detected as a rectangular wave as shown by the dotted line part of the tracking error signal a, the eccentricity is accurately obtained. Needless to say, the phase of can be detected.

According to the present invention, the tracking error signal of the optical disc is shaped into a rectangular wave, the width of the rectangular wave is stored once, and the maximum rectangular wave width is detected from the waveform, and at least 2 is centered on the maximum rectangular wave width. By determining the intermediate value from the rectangular wave width of the previous one or more to the rectangular wave width after the same number, by the configuration of obtaining the phase of eccentricity from the intermediate value and the sum of the stored rectangular wave width,
It is possible to realize an eccentricity phase detection device for an excellent-wave optical disc that can improve the detection deviation of the eccentricity phase due to the disturbance of the tracking error signal near the maximum rectangular wave width.

[Brief description of drawings]

FIG. 1 is a schematic block diagram of an optical disk eccentricity detection device according to an embodiment of the present invention, FIG. 2 is a waveform diagram of output signals of respective parts, FIG. FIG. 5 is a schematic block diagram of the optical disk eccentricity phase detecting device, FIG. 5 is a waveform diagram of output signals of respective portions, and FIG. 6 is a flowchart showing the outline of the same operation. 1 ... Optical disc, 2 ... Optical head, 4 ... Pulse generating means, 5 ... Waveform shaping means, 6 ... Rectangular wave width detecting means, 7 ... Storage means, 8 ... First computing means, 9 ... ... second arithmetic means, 10 ... third arithmetic means.

Claims (1)

[Claims] 1. An optical disc, a pulse generating means for generating a pulse synchronizing with the rotation of the optical disc, an optical head, and a tracking error signal representing a deviation of a light spot detected by the optical head from a track of the optical disc. Waveform shaping means for shaping the rectangular wave into a rectangular wave, a rectangular wave width detecting means for detecting the width of the rectangular wave output from the waveform shaping means, and a storage means for sequentially storing the rectangular wave widths detected by the rectangular wave width detecting means. First arithmetic means for obtaining the maximum rectangular wave width of the rectangular wave width stored in the storage means, and at least two or more points in front of the rectangular wave of the maximum rectangular wave width obtained by the first arithmetic means From the pulse output from the pulse generating means, the second arithmetic means for obtaining an intermediate value from the rectangular wave widths stored in Serial second third of obtaining the eccentricity phase from the width of to an intermediate value calculated by the calculation means of calculating means and the phase detection device of the eccentricity of the optical disc, characterized in that it comprises a.