JP2002042344A - Optical disk device and pll circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a highly reliable high speed optical disk device capable of reducing the start time and read out time. SOLUTION: The optical disk device is constituted with the initial area being divided into plural 1st dividing areas, and one area among plural 1st dividing areas is searched, where a minimum jitter is measured among the jitters measured at plural 1st jitter measuring points respectively positioned at centroids of the plural 1st dividing areas. Then, one area among plural 1st dividing areas is divided into plural 2nd dividing areas; and one area among the plural 2nd dividing areas is searched, where the minimum jitter is measured among the jitters measured at plural 2nd jitter measuring points respectively positioned at centroids of the plural 2nd dividing areas; and then a search means of the minimum jitter value is provided for deciding the optimum combination between a variable X and a variable Y, corresponding to one point among the plural 2nd jitter measuring points included in one area among the plural 2nd dividing areas.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk apparatus for optically reproducing a signal on an information carrier using a light beam from a light source such as a semiconductor laser, and a PLL circuit for removing an offset of a data slice balance circuit. Things.

[0002]

2. Description of the Related Art In an optical disk apparatus for reproducing an optical disk as an information carrier, a disc-shaped information carrier (optical disk) rotating at a predetermined rotation number is convergently irradiated with a light beam generated from a light source such as a semiconductor laser. There is something to play. On this information carrier, minute tracks are formed in a spiral shape as an information pit row. Generally, in an optical disk device, rotation control for rotating the optical disk at a predetermined number of rotations, focus control for a light beam irradiated on the optical disk to be in a predetermined convergence state, and a light beam for a track on an information carrier correctly. Tracking control such as scanning is performed.

[0003] Optical discs include CD audio,
Read-only type in which information such as CD-ROM and DVD-ROM is recorded in a pit row, one-time recording type such as CD-R and DVD-R, CD-RW, DVD-RAM, DVD-
Since there are various types up to the recording / reproducing type such as RW, the recording density, the reflectivity of the disc and the reproduction signal are different for each optical disc. Therefore, it is necessary to optimize the reproducing method according to the characteristics of each optical disc. In particular, when reproducing two or more types of disks or switching the reproducing speed, the reproducing method is optimized by adapting the frequency characteristics of the waveform equalizer included in the optical disk device.

FIG. 27 is a graph showing frequency characteristics of gain and noise of a waveform equalizer. Although the reproduced signal from the optical disk is a random signal, the gain of the high frequency signal component is extremely lower than that of the low frequency signal component due to intersymbol interference. Therefore, as shown in FIG. 27, a predetermined frequency FC in the reproduced signal is boosted by a waveform equalizer to improve the gain of a high-frequency signal component, and the gain is rapidly reduced by a higher-order equiripple filter or the like. Then, noise in a frequency band higher than a predetermined frequency FC is removed to improve the quality of a reproduced signal.

FIG. 28 is a graph showing the characteristics of the jitter with respect to the focus position. When the focus position deviates from the optimum position (just focus position 2701), jitter deteriorates. This is because the gain of the reproduction signal shown in FIG. 27 decreases, the SN ratio of the reproduction signal deteriorates, and the reproduction signal quality deteriorates. Is what happens for you. In order to detect jitter and determine the optimal frequency characteristic of waveform equalization that minimizes the jitter, it is necessary to adjust the focus position to the just focus position 2701.

As a conventional technique for realizing this, the jitter of a reproduced signal whose waveform has been equalized is measured, and the focus position, which is the focal position, and the cutoff frequency of the waveform equalizer are two-dimensionally varied so that the jitter is minimized. There is a configuration that optimizes the focus position and cutoff frequency so that
657).

[0007]

In the conventional optical disk apparatus having the above configuration, the combination of the two parameters such as the focus position and the cutoff frequency is all executed, and the jitter at that time is measured (the jitter is minimized). ), The reproduction signal quality was secured.

However, as described above, the types of media (optical disks) to be reproduced are increasing, and in particular, CD-R / RW
When playing back recording media such as DVDs and DVD-R / RW / RAM, the focus position must be adjusted independently of the cut-off frequency and the cut-off frequency and boost amount must be optimally matched to improve the jitter. did.

Also, the type of reproduction speed of each disk, for example, 48 times speed from CD standard speed, or 1 time from DVD standard speed.
When the type of signal frequency band is greatly increased, such as 6 times speed, all combinations of parameters are executed for each type of reproduction speed at each start-up, and the jitter at that time is measured (the jitter is minimized). If the combination is determined, the startup time increases. Alternatively, when all combinations of parameters are executed at the time of switching the reproduction speed, and the jitter at that time is measured to find the best (minimized jitter) combination, the problem arises that reading cannot be executed immediately. .

An object of the present invention is to provide a high-reliability and high-speed optical disk device that can respond to various types of optical disks and switches the reproduction speed in multiple stages, and can shorten the start-up time and the read time. It is in.

Another object of the present invention is to provide an optical disk apparatus and a PLL circuit that can efficiently and quickly determine a combination of parameters that minimizes jitter.

[0012]

An optical disk device according to the present invention is an optical disk device for optically reproducing information recorded on an information carrier by a light beam emitted from a light source, wherein the light beam is convergently irradiated with the light beam. Converging means, a light detecting means for generating a reproduced signal corresponding to the reflected light or transmitted light of the light beam from the information carrier, and a waveform for changing a frequency characteristic of the reproduced signal generated by the light detecting means Equalization means, jitter measurement means for measuring jitter of an output signal from the waveform equalization means, and variables X and Y which can change the jitter measured by the jitter measurement means are defined by two variables. And a jitter minimum value searching means for obtaining the minimum value of the jitter in the initial region on the XY plane. Is divided into a plurality of first divided regions having the same shape as each other, and the minimum jitter among the jitters measured at the plurality of first jitter measurement points respectively located at the centers of gravity of the plurality of first divided regions is measured. One of the plurality of first divided areas is searched, and the minimum jitter value searching means is configured to convert the one of the searched plurality of first divided areas into a plurality of second divided areas having the same shape. The plurality of second divided areas, each of which has the smallest jitter among the jitters measured at the plurality of second jitter measurement points respectively positioned at the center of gravity of the plurality of second divided areas. One of the plurality of second divided areas searched for, and the optimum of the variable X and the variable Y corresponding to one of the plurality of second jitter measurement points included in the one of the plurality of second divided areas searched for. Determine the combination and The above-mentioned object can be achieved by.

The jitter minimum value searching means divides the initial area into four first divided areas having the same square shape, and four first jitters respectively located at the centers of gravity of the four first divided areas. One of the four first divided regions in which the minimum jitter is measured among the jitters measured at the measurement point is searched, and the jitter minimum value searching means searches the four first divided regions in the searched four first divided regions. The one of them is divided into four second divided regions having the same shape, and the smallest of the jitters measured at the four second jitter measurement points respectively located at the centers of gravity of the four second divided regions. One of the four second divided regions where jitter has been measured may be searched.

When the value of the jitter measured by the jitter measuring means is equal to or less than a predetermined value, the minimum jitter value searching means may end the search operation.

When the jitter measuring means cannot measure the jitter in a certain area, the jitter measuring means omits the measurement in the area where the jitter cannot be measured, and May be searched.

[0016] The variable X may include a cutoff frequency, and the variable Y may include a boost amount.

The variable X may include a high-frequency delay, and the variable Y may include a low-frequency delay.

Focus control means for controlling the convergence means so that the light beam is brought into a predetermined convergence state with respect to the record carrier; and the focus control means so that the light beam scans a track on the record carrier correctly. The variable X may include a tracking position, and the variable Y may include a focus position.

The apparatus further includes radial tilt adjusting means for adjusting the tilt of the light beam in the radial direction with respect to the record carrier, and tangential tilt adjusting means for adjusting the tilt of the light beam in the tangential direction with respect to the record carrier. , The variable X may include a radial tilt, and the variable Y may include a tangential tilt.

Another optical disk device according to the present invention is an optical disk device for optically reproducing information recorded on an information carrier by a light beam emitted from a light source, comprising a converging means for converging and irradiating the light beam. Light detection means for generating a reproduction signal corresponding to reflected light or transmitted light of the light beam from the information carrier, and waveform equalization means for changing a frequency characteristic of the reproduction signal generated by the light detection means; An XY plane defined by two variables, a jitter measuring means for measuring jitter of an output signal from the waveform equalizing means, and a variable X and a variable Y capable of changing the jitter measured by the jitter measuring means. A jitter minimum value searching means for obtaining a minimum value of the jitter in the initial region, and an information carrier determining means for determining a type of the information carrier; The jitter minimum value searching means divides the initial area into a plurality of first divided areas having the same shape as each other, and based on the type of the information carrier determined by the information carrier determining means, Selecting one of the areas, the jitter minimum value searching means divides the selected one of the plurality of first divided areas into a plurality of second divided areas having shapes equal to each other, One of the plurality of second divided regions where the minimum jitter is measured among the jitters measured at the plurality of jitter measurement points respectively located at the centers of gravity of the plurality of second divided regions, and the searched Determining an optimal combination of the variable X and the variable Y corresponding to one of the plurality of jitter measurement points included in the one of the plurality of second divided areas, thereby determining the object; But It is.

The minimum jitter value searching means divides the initial area into four first divided areas having the same rectangular shape, and based on the type of the information carrier determined by the information carrier determining means, One of the four first divided areas is selected, and the minimum jitter value searching means selects one of the selected four first divided areas into four first divided areas having the same square shape. Of the jitters measured at the four second jitter measurement points respectively located at the centers of gravity of the four second divided areas, the four second divided areas in which the smallest jitter was measured were divided into two divided areas. May be searched.

The variable X may include a cutoff frequency, and the variable Y may include a boost amount.

The variable X may include a high-frequency delay amount, and the variable Y may include a low-frequency delay amount.

Focus control means for controlling the convergence means so that the light beam is brought into a predetermined convergence state with respect to the record carrier; and the convergence means so that the light beam scans a track on the record carrier correctly. The variable X may include a tracking position, and the variable Y may include a focus position.

The apparatus further includes radial tilt adjusting means for adjusting the tilt of the light beam in the radial direction with respect to the record carrier, and tangential tilt adjusting means for adjusting the tilt of the light beam in the tangential direction with respect to the record carrier. , The variable X may include a radial tilt, and the variable Y may include a tangential tilt.

Still another optical disk device according to the present invention is an optical disk device for optically reproducing information recorded on an information carrier by a light beam emitted from a light source, wherein a converging means for converging and irradiating the light beam Light detection means for generating a reproduction signal corresponding to reflected light or transmitted light of the light beam from the information carrier; and waveform equalization means for changing a frequency characteristic of the reproduction signal generated by the light detection means. XY defined by two variables, a jitter measuring means for measuring the jitter of the output signal from the waveform equalizing means, and a variable X and a variable Y capable of changing the jitter measured by the jitter measuring means. A jitter minimum value searching means for obtaining a minimum value of the jitter in an initial area on a plane, and a reproducing speed detecting means for detecting a reproducing speed of the reproduced signal; The minimum jitter value searching means divides the initial area into a plurality of first divided areas having the same shape, and based on the reproduction speed detected by the reproduction speed detection means, Selecting one of the divided regions, the jitter minimum value searching means divides the searched one of the plurality of first divided regions into a plurality of second divided regions having mutually equal shapes, One of the plurality of second divided regions where the minimum jitter was measured among the jitters measured at the plurality of jitter measurement points respectively located at the centers of gravity of the plurality of second divided regions was searched and searched. Determining an optimal combination of the variable X and the variable Y corresponding to one of the plurality of jitter measurement points included in the one of the plurality of second divided regions, and Purpose It is achieved.

The minimum jitter value searching means divides the initial area into four first divided areas having the same rectangular shape, and based on the reproduction speed detected by the reproduction speed detection means, One of the first divided regions is selected, and the jitter minimum value searching means selects one of the selected four first divided regions into four second divided regions having a square shape equal to each other. Divided into regions, and one of the four second divided regions in which the minimum jitter is measured among the jitters measured at the four jitter measurement points respectively located at the centers of gravity of the four second divided regions.
You may search for one.

The variable X may include a cutoff frequency, and the variable Y may include a boost amount. PL according to the present invention
The L circuit includes a reference signal generating unit that generates a monotonous signal, a binarizing unit that binarizes the monotonic signal, and the binarizing unit that binarizes a signal amplitude center of the monotonic signal.
Data slice balance setting means for setting a value conversion circuit; clock generation means for generating a clock signal; the monotone signal binarized by the binarization means; and the clock signal generated by the clock signal generation means Phase comparison means for comparing the phase with the phase error signal, a charge pump circuit for averaging the phase error signal output from the phase comparison means, and the phase error output from the phase comparison means. Phase adjusting means for adjusting a phase shift of a signal, jitter measuring means for measuring jitter based on the phase error signal output from the phase comparing means, and changing the jitter measured by the jitter measuring means. Variable X and variable Y
Jitter minimum value searching means for obtaining a minimum value of the jitter in an initial area on an XY plane defined by a variable,
The minimum jitter value searching means divides the initial area into a plurality of first divided areas having the same shape, and a plurality of first divided areas respectively located at the centers of gravity of the plurality of first divided areas.
One of the plurality of first divided regions in which the minimum jitter is measured among the jitters measured at the jitter measurement point is searched, and the minimum jitter value searching means searches the plurality of first divided regions. Is divided into a plurality of second divided regions having the same shape as each other, and the minimum of the jitters measured at the plurality of second jitter measurement points respectively located at the centers of gravity of the plurality of second divided regions is determined. Searching for one of the plurality of second divided areas where the jitter has been measured, among the plurality of second jitter measurement points included in the one of the searched plurality of second divided areas. An optimal combination of the variable X and the variable Y corresponding to one of the above is determined, thereby achieving the above object.

The variable X may include a cutoff frequency, and the variable Y may include a boost amount.

[0030] The phase adjusting means may vary a current balance in an output stage included in the charge pump circuit so as to adjust the phase shift of the phase error signal output from the phase comparing means.

[0031]

Embodiments of the present invention will be described with reference to the drawings. In the drawings, members having the same functions are denoted by the same reference numerals.

(Embodiment 1) In the first embodiment, as a variable that can change the jitter, the jitter is reduced in each area obtained by dividing the XY plane with a cutoff frequency as a variable X and a boost amount as a variable Y at a predetermined ratio. This is a configuration for obtaining a minimum area, further dividing the area into smaller areas, repeatedly obtaining an area with the minimum jitter, and determining an optimal combination of variables X and Y. Here, for simplicity of explanation, a configuration for realizing a method of determining an optimal combination of a cutoff frequency and a boost amount will be described as an example.

FIG. 1 is a block diagram for explaining the configuration of the optical disk device 100 according to the first embodiment. As shown in FIG. 1, an optical disk device 100 includes an optical head 2 for converging and irradiating a light beam emitted from a light source such as a semiconductor laser onto an optical disk 1 as an information carrier, and an optical disk 1 output from the optical head 2. Preamplifier 3 for amplifying a reproduction signal corresponding to the reflected light of the above, and a waveform equalizing circuit 4 for equalizing the waveform of the reproduction signal amplified by the preamplifier 3
A binarizing circuit 13 for pulsing the reproduced signal whose waveform has been equalized by the waveform equalizing circuit 4, a jitter detecting circuit 5 for detecting jitter of the pulsed reproduced signal, and a reproduction amplified by the preamplifier 3. An amplitude detection circuit 8 for detecting the amplitude of a signal, and a control unit 7 for controlling the optical head 2 so that a light beam converged and irradiated from the optical head 2 onto the optical disk 1 is in an optimum convergence state.

The control section 7 includes a minimum value jitter detecting section 6 for detecting the minimum value of the jitter detected by the jitter detecting circuit 5 and a focus position at which the amplitude of the reproduced signal detected by the amplitude detecting circuit 8 becomes maximum. A maximum amplitude search unit 9 for searching, a focus control unit 10 for executing focus control so that a light beam emitted from the optical head 2 is in an optimum convergence state on the optical disk 1, and a light emitted from the optical head 2 A tracking control unit 12 that performs tracking control so that the beam scans a track on the optical disc 1 correctly; and a signal from the maximum amplitude search unit 9 is a focus control signal from the focus control unit 10 and tracking from the tracking control unit 10. A synthesizing circuit 11 for synthesizing with the control signal.

In order to set the target position of the focus control unit 10, that is, the focus position, such that the light beam emitted from the optical head 2 converges optimally on the optical disc 1, the amplitude detection circuit 8 reproduces the preamplifier 3. Detect the amplitude of the signal. The control device 7 also includes a tracking control unit 12, but the tracking control is not directly related to the present invention, and thus a detailed description is omitted.

The reproduced signal whose waveform has been equalized by the waveform equalizing circuit 4 is pulsed by the binarizing circuit 13, and its jitter is detected by the jitter detector 5. Jitter detection circuit 5
Detects the jitter by converting the phase error between the reproduction signal pulsed by the binarization circuit 13 and the PLL clock into a voltage.

The jitter detected by the jitter detection circuit 5 is converted into a minimum value jitter search section 6 for searching for the minimum value of the jitter.
Is input to The minimum value jitter search unit 6 sets the frequency characteristics of the waveform equalization circuit 4 by giving the cutoff frequency FC and the boost amount BST to the waveform equalization circuit 4 so that the jitter is minimized. Thus, the information recorded on the optical disc 1 is reproduced through the filter of the waveform equalizing circuit 4 having the frequency characteristics set optimally.

The search operation of the minimum jitter detector 6 in the first embodiment using the above-described configuration will be described in detail.

The waveform equalizing circuit 4 has a configuration in which a cutoff frequency FC for removing a high-frequency noise component of the reproduced signal and a boost amount BST for relatively increasing the high-frequency component of the reproduced signal are variable. ing. The waveform equalizing circuit 4 can be configured using an active filter such as a Bessel filter or an equiripple filter. The reproduced signal whose waveform has been equalized by the waveform equalizer 4 as described above is binarized by the binarizer 13. Using the jitter detected by the jitter detection circuit 5, the minimum value jitter search unit 6 sets the cut-off frequency FC and the boost amount BST in the waveform equalization circuit 4 so that the jitter is minimized.

In order to explain the minimum jitter searching method executed by the minimum jitter searching section 6, first, the relationship among the cutoff frequency FC, the boost amount BST, and the jitter will be described.

FIGS. 2A, 2B and 2
(C) is a graph showing a relationship between the cutoff frequency FC, the boost amount BST, and the jitter contour according to the first embodiment. This graph is used to search for the minimum value of the jitter defined by the cutoff frequency FC of the waveform equalization circuit 4 and the boost amount BST. The rectangular coordinate system 201 is defined by a cutoff frequency FC, a boost amount BST, and jitter. Generally, the jitter of the reproduction signal from the optical disk does not become an independent variable with respect to the cutoff frequency FC and the boost amount BST. This is because, in the reproduction signal from the optical disk, if the cutoff frequency FC is increased, high-frequency noise increases and jitter increases. Also, if the cutoff frequency FC is decreased, the ratio of the reproduction signal component to the noise component is reduced. This is because, regardless of whether the cutoff frequency FC is increased or decreased, the SN ratio of the reproduced signal deteriorates and the jitter increases, and the same applies to the boost amount BST as with the cutoff frequency FC.

Therefore, when the points showing the same jitter value when the cut-off frequency FC and the boost amount BST are varied are connected, FIG. 2 (a), FIG. 2 (b) and FIG.
As shown in (c), the jitter contour line 2 on a plane having the cutoff frequency FC as the horizontal axis and the boost amount BST as the vertical axis.
05A, 205B and 205C can be drawn.
Here, ΔJ indicates the jitter contour line interval, and the jitter characteristic can be estimated from the magnitude of the jitter contour line interval ΔJ.

When the correlation between the boost amount BST and the jitter is stronger than the correlation between the cutoff frequency FC and the jitter, the jitter characteristic is indicated by the jitter contour 205A on the graph 202. Conversely, when the correlation between the cutoff frequency FC and the jitter is stronger than the correlation between the boost amount BST and the jitter, the jitter characteristic indicated by the jitter contour 205C on the graph 204 is obtained. When the correlation between the boost amount BST and the jitter is substantially equal to the correlation between the cutoff frequency FC and the jitter, the jitter characteristic is indicated by the jitter contour 205B on the graph 203. As described above, there are various types of optical disks, and the jitter characteristics also vary depending on the various types of optical disks described above.

The horizontal axis represents the cutoff frequency FC, and the boost amount B
The position where the jitter is minimized is determined on a plane having ST as the vertical axis, and the cutoff frequency FC and the boost amount BST corresponding to the position where the determined jitter is minimized are obtained, whereby the optimal equalization amount is waveform-equalized. This can be set in the circuit 4.

Referring to FIGS. 3, 4 and 5, the method for searching for the minimum jitter according to the first embodiment will be described. FIG.
FIG. 3 is a diagram for explaining a minimum jitter area search method according to the first embodiment. FIG. 4 is a graph for explaining the minimum jitter area according to the first embodiment. FIG. 5 is a flowchart illustrating the minimum jitter area search method according to the first embodiment.

In FIG. 3, the horizontal axis represents the cutoff frequency FC, and the vertical axis represents the boost amount BST. As shown in FIG. 3, it is assumed that the cutoff frequency FC and the boost amount BST have a variable width of 8 steps in the initial area 301 for simplification of the description. As shown in FIG. 3A, the initial area 301 has a square shape. The initial area 301 is
Includes divided areas A1, A2, A3 and A4. FIG.
As shown in (a), divided areas A1, A2, A3 and A
4 has a square shape. The initial area 301 is equally divided by the divided areas A1, A2, A3, and A4. The initial area 301 further includes a divided area A0. As shown in FIG. 3A, the divided area A0 has a square shape, and is arranged at the position of the center of gravity of the initial area 301.
Each of the divided areas A1, A2, A3 and A4 overlaps by a quarter area.

As shown in FIG. 3A, each divided area A
0, A1, A2, A3 and A4 are jitter measurement points J
0, J1, J2, J3, and J4. Each jitter measurement point J0, J1, J2, J3, J4 is defined by each of the divided areas A0, A
It is arranged at the position of the center of gravity of 1, A2, A3 and A4.

The divided area A4 corresponding to the measurement point J4 is further divided into smaller divided areas. That is, the divided area A4
Includes divided areas B1, B2, B3 and B4. FIG.
As shown in (b), the divided areas B1, B2, B3 and B
4 has a square shape. The divided area A4 is equally divided by the divided areas B1, B2, B3 and B4. The divided area A4 further includes a divided area B0. FIG.
As shown in (b), the divided area B0 has a square shape and is arranged at the position of the center of gravity of the divided area A4, and each of the divided areas B1, B2, B3 and B4 has a quarter of the area. Overlap each other.

As shown in FIG. 3B, each divided area B
0, B1, B2, B3 and B4 are the jitter measurement points J
4, J5, J6, J7 and J8. The jitter measurement points J4, J5, J6, J7, and J8 are arranged at the positions of the centers of gravity of the divided areas B0, B1, B2, B3, and B4.

In the initial area A, four divided areas A 1 and A 1 divided by thick lines 302 and 303 having a cutoff frequency FC of 4 and a boost amount BST of 4 at right angles.
2. Make A3 and A4. These four divided areas A
Four points of jitter measurement points J1, J2, J3 and J4 are determined as points for measuring jitter at 1, A2, A3 and A4. Next, these four jitter measurement points J1, J
2. Jitter is measured at J3 and J4, and the area having the smallest jitter among the four divided areas A1, A2, A3 and A4 is compared and determined. If all four points have the same jitter value, the jitter is determined. Cannot be determined.

Therefore, J0, which is in contact with all of the four divided areas A1, A2, A3 and A4, is defined as a jitter measurement point.
The jitter at the jitter measurement point J0 was also measured, and when the five jitter measurement values were the same, the jitter measurement point J0 was determined.
The cutoff frequency FC at 0 and the boost value BST are determined as optimal values.

Assuming that the jitter characteristic in the initial area 301 is indicated by a jitter contour 205D on the graph 302 shown in FIG. 4, according to the jitter characteristic shown in FIG. 4, the five jitter measurement points J0 and J1 are obtained. , J2,
The jitter measuring point at which the measured jitter is the minimum among J3 and J4 is the jitter measuring point J4.

Next, in a region A4 corresponding to the jitter measurement point J4, two straight lines 304 and 30 orthogonal to each other with a cutoff frequency FC of 2 and a boost amount BST of 2 are orthogonal.
5, four divided areas B1 and B that divide the area A4
2, B3 and B4 are set again, and the jitter measurement point J5,
Four points J6, J7 and J8 are determined. The jitter at these four jitter measurement points J5, J6, J7 and J8 was measured, and the four divided areas B1, B2, B3 and B were measured.
The area having the smallest jitter among the areas 4 is determined by comparison. FIG.
It can be seen from the jitter characteristics of (1) that the minimum jitter position is the jitter measurement point J4.

Since the width between the jitter measurement point J4 and the other four jitter measurement points J5, J6, J7 and J8 in the area A4 is 1, which is the minimum unit set width, the jitter measurement point J4 is located at the minimum jitter position. Become. This jitter measurement point J
By setting the cutoff frequency FC and the boost amount BST corresponding to 4, the optimization of the frequency characteristics of the waveform equalization circuit 4 is completed.

The relationship between the method of dividing the minimum jitter search area and the jitter measurement point will be described. First, a method of dividing the minimum jitter search area will be described. FIGS. 6A and 6B are diagrams illustrating jitter measurement points in the minimum jitter area searching method according to the first embodiment. At all the jitter measurement points on the initial area 301, the probability that the measured jitter becomes the minimum jitter is equal. Therefore, in each stage of searching for the minimum jitter in each divided region, the probability that the measured jitter becomes the minimum jitter is equal at all jitter measurement points on each divided region.

As shown in FIG. 3A, the divided areas A1, A
It is preferable that the jitter measurement points J1, J2, J3 and J4 of 2, A3 and A4 coincide with the centers of gravity of the divided areas A1, A2, A3 and A4. As shown in FIG. 6A, when at least one of the jitter measurement points in the divided area is arranged at a position shifted from the center of gravity of the divided area, the jitter measurement point J in all the divided areas A1, A2, A3 and A4 is obtained.
1, J2, J3 and J4 are divided areas A1, A2, A3
This is because, as compared with the case where the center of gravity coincides with the center of gravity of A4 and A4, a larger number of searches is required to search for the divided region with the minimum jitter as described below.

As shown in FIG. 6A, the divided area A
1, A3 and A4 jitter measurement points J1, J3 and J
4 matches the center of gravity of the divided areas A1, A3 and A4. The jitter measurement point JC0 of the divided area A2 is located at a position shifted from the center of gravity G1 of the divided area A2. When the jitter measured at the jitter measurement point JC0 arranged at a position shifted from the center of gravity G1 of the divided area A2 is the minimum jitter among the jitter measured at the jitter measurement points J1, J3, J4 and JC0, Divided area 2 shown in FIG.
500 is set. The divided area 2500 is a square. One-half of the length of the diagonal line of the divided area 2500 is equal to the length of a line segment 2501 connecting the jitter measurement points J0 and JC0. The divided area 2500 further includes a cutoff frequency FC
Is a straight line 3 having a value of 7 and a boost amount BST of 7 and orthogonal to each other.
06 and 307, the four divided areas C1, C2,
It is divided into C3 and C4. The jitter measurement points JC1, JC2 and JC3 of the divided areas C1, C2 and C3 are
The center of gravity of the divided areas C1, C2 and C3 coincides with the center of gravity.
The jitter measurement point JC4 of the divided area C4 is located at a position shifted from the center of gravity G2 of the divided area C4.

Assuming that the length of the diagonal line of the region 301 shown in FIG. 6A is 100%, the length of the line segment 2501 is 40%. As shown in FIG. 6B, the jitter measurement points within the initial area 301 are the jitter measurement points JC1 and JC1.
2, JC3 and JC4 are only the jitter measurement point JC2. Since the jitter measurement points JC1, JC3 and JC4 are outside the initial area 301, the jitter measurement points JC1, JC1, JC4
C3 and JC4 require processing of a program that does not measure. Therefore, the jitter measurement points JC0 and JC0
Jitter is measured only at C2. When the position where the jitter becomes minimum is located at a position other than between the jitter measurement points JC0 and JC2, it is necessary to search for a position where the jitter becomes minimum by further setting a new divided area.

The jitter measuring point of the divided area A2 is the jitter measuring point JCX, which is located at a position shifted from the center of gravity G1 of the divided area A2 toward the jitter measuring point J0.
Suppose that the length of 01 is 20%. At this time, the divided area 2500 is small enough not to cover the divided area A2. The position where the jitter is minimized is the jitter measurement point JC0.
If it is located at a position other than between the position and the JCX, a new divided region must be set to search for a position where the jitter is minimized.

As described above, when at least one of the jitter measurement points in the divided area is arranged at a position shifted from the center of gravity of the divided area, the jitter measurement points J1, J2 in all the divided areas A1, A2, A3 and A4 are set. , J3, and J4 require a larger number of search times to search for the divided region with the minimum jitter than when the center of gravity of the divided regions A1, A2, A3, and A4 is coincident.

If the initial area and the divided area are divided into four squares or rectangles, the program for the search processing can be simplified. The jitter shown in FIG. 4 changes continuously and does not change stepwise. This is because the probability of occurrence of jitter, which is generally used as an index of the quality of a reproduced signal in an optical disc device, is normally distributed. FIG.
Are not parallel to the axis of the cutoff frequency FC or the axis of the boost amount BST. Waveform equalization characteristics of the waveform equalization means (cutoff frequency FC and boost amount B
This is because when ST) changes, the jitter also changes. Further, in the initial region for searching for the position where the jitter is minimized, there is substantially no plurality of positions where the jitter is minimized. Even if the position where the jitter is minimum exists outside the initial region, it is possible to search for the position where the jitter is minimum in the initial region unless there are multiple positions where the jitter is minimum. I can do it. Therefore, unless the transmission characteristics of the signal system of the optical disk device are extremely deteriorated, it is possible to search for the position where the jitter is minimized in the initial area.

In FIG. 5, steps 501 to 504 show the process of searching for the minimum value in the initial area 301, and steps 505 to 510 show the process of searching for the minimum position in the area A4.

The minimum jitter searching means for executing the minimum position searching process is a digital signal processor (DSP).
And it can be realized by firmware such as a central processing unit (CPU).

In the initial area 301, five jitter measurement points J0, J1, J2, J3 and J4 are set (step 501). An equivalent amount corresponding to one of the jitter measurement points J0, J1, J2, J3, and J4, that is, a cutoff frequency FC and a boost value BST are set (step 5).
02). Set cutoff frequency FC and boost value BST
Is measured based on the above (step 503). 5
It is determined whether or not the jitter has been measured at all the jitter measurement points J0, J1, J2, J3 and J4 (step 504). 5 jitter measurement points J
If it is determined that the jitter has not been measured at all the jitter measurement points 0, J1, J2, J3 and J4 (NO in step 504), the five jitter measurement points J
The process returns to step 502 in order to measure the jitter at the jitter measurement point at which the jitter has not yet been measured among 0, J1, J2, J3 and J4. Five jitter measurement points J0,
If it is determined that the jitter has been measured at all the jitter measurement points J1, J2, J3 and J4 (YES in step 504), the five jitter measurement points J0, J1,.
A jitter measurement point at which the measured jitter is minimum among J2, J3 and J4 is determined (step 505). Below 5
The description will be given taking an example in which the jitter measurement point having the smallest measured jitter among the jitter measurement points J0, J1, J2, J3 and J4 is the jitter measurement point J4.

Four jitter measurement points J5, J6, J7 and J8 are set in the divided area A4 corresponding to the jitter measurement point J4 where the measured jitter is the minimum (step 5).
06). Jitter measurement points J4, J5, J6, J7 and J
8 or the cut-off frequency F
C and the boost value BST are set, and the jitter is measured based on the set cutoff frequency FC and boost value BST (step 507). 5 jitter measurement points J4, J
It is determined whether or not the jitter has been measured at all the jitter measurement points 5, 5, J6, J7 and J8 (whether the number of measurement operations is 5) (step 508). If it is determined that the jitter has not been measured at all of the five jitter measurement points J4, J5, J6, J7 and J8 (NO in step 508), the five jitter measurement points J4, J5, The process returns to step 506 in order to measure the jitter at the jitter measurement point of which jitter has not yet been measured among J6, J7, and J8. 5 jitter measurement points J
If it is determined that the jitter measurement operation has been performed at all the jitter measurement points 4, 4, J6, J7, and J8 (YES in step 508), the jitter measurement point J4 in the area A4 and the other four jitter measurement points J5, J6, J7
It is determined whether or not the width between J8 and J8 is 1 and the minimum unit setting width is set (step 509). The minimum unit setting width here is two variables that vary the jitter.
The minimum unit setting width of the cutoff frequency FC and the boost amount BST.

If it is determined that the width between the jitter measuring point J4 and the other four jitter measuring points J5, J6, J7 and J8 is not the minimum unit set width (step 5).
(NO at 09), the process returns to step 505. Jitter measurement point J
4 and 4 other jitter measurement points J5, J6, J7 and J
8 is determined to be the minimum unit setting width (YES in step 509), the measured jitter among the five jitter measurement points J4, J5, J6, J7 and J8 is the minimum. Is determined, and an equivalent amount, ie, a cutoff frequency FC and a boost value BST, corresponding to the jitter measurement point at which the measured jitter is minimum are set (step 510).

Next, a general algorithm when the above-described method of setting the jitter measurement point is executed by a digital signal processor or the like will be described.

Variables are sequentially defined as follows.

1. The variable ranges of the cutoff frequency FC and the boost amount BST are defined as FCtoral and BSTtota, respectively.
l.

2. Let J be the jitter on a plane defined by the cutoff frequency FC and the boost amount BST.

3. α is an initial cutoff frequency, and β is an initial boost amount.

4. The width between the jitter measurement points in the initial area or the divided area corresponding to the jitter measurement point at which the jitter is the minimum is ΔX with respect to the cutoff frequency and Δ with respect to the boost amount.
Let it be Y.

5. It is assumed that the divided area corresponding to the jitter measurement point at which the minimum jitter is obtained is the r-th divided area.

Under these conditions, the initial cutoff frequency FC
(Α, β) = (FCtotal / 2, BSTtotal / 2) (1), and the representative point setting variable width is ΔX = FCtotal / 2 ^{(r + 1).} (2-1) Assuming that ΔY = BSTtotal / 2 ^{(r + 1)} (2-2), the jitter measurement point in the initial region is Jc (α + ΔX, β + ΔY) (4-1) Jb (α−ΔX, β + ΔY) ( 4-2) Ja (α, β) (4-3) Jd (α + ΔX, β−ΔY) (4-4) Je (α−ΔX, β−ΔY) (4-5) be able to.

Next, the jitter measurement point in the r-th divided area is Jc ′ (α ′ + ΔX, β ′ + ΔY) (5-1) Jb ′ (α′−ΔX, β ′ + ΔY) (5-2) Ja ′ (α ′, β ′) (5-3) Jd ′ (α ′ + ΔX, β′−ΔY) (5-4) Je ′ (α′−ΔX, β′−ΔY) (5-5) Five points can be determined. Here, α ′ and β ′ are sequentially updated to the jitter measurement point having the smallest measured jitter among the five jitter measurement points.

Further, ΔX and ΔY also change according to the value of r representing the number of divisions. From Equation (5-1) to Equation (5)
In -5), the cutoff frequency FC and the boost amount BST corresponding to the jitter measurement point at which the jitter becomes minimum are set.

When the above formula is executed by a DSP or firmware, it can be executed by repetitive processing by the same arithmetic module, so that the amount of waveform equalization, that is, the cutoff with less resources (program capacity and work area) The frequency FC and the boost amount BST can be set.

If the jitter cannot be measured in the area where the PLL or servo is off, the optimum cut-off frequency FC and the boost can be obtained by omitting the measurement in the area where the jitter cannot be measured and exploring the minimum jitter area. The quantity BST can be determined quickly.

Further, a method for effectively using the basic module will be described. FIG. 7 is a diagram for explaining the measurement order of the jitter measurement points in the minimum jitter area search method according to the first embodiment. FIG. 7 shows an initial area 601 defined by the cutoff frequency FC and the boost amount BST as a jitter measurement plane. As described above, the jitter measurement is performed for each of the divided regions 602, 603, 604, 605, and 60.
6, there is a method in which the order of measurement is always constant.

As shown in FIG. 7, the initial area 601 has five divided areas 602, 603, 604, 605 and 60.
6. First, the jitter in the divided region 602 is measured, and then the jitter is measured in the order of the divided region 603, the divided region 604, the divided region 605, and the divided region 606. This is because five divided regions 602, 603, 604, and 605 are also provided at each stage of further dividing the divided region.
And five divided regions having the same positional relationship as 606 and 606 are set and measured in the same order. If the order of measurement with respect to the divided areas to be measured is kept constant in this way, it is possible to execute the processing by repeated processing by the same arithmetic module, so that the processing of μ code and firmware is simplified.

In the above-described minimum jitter search, ideally, it is preferable to precisely search by repeatedly dividing the region up to the limit of the resolution performance of the cutoff frequency FC and the boost amount BST of the waveform equalizing circuit. If the detection sensitivity is lower than the resolution of the cutoff frequency FC and the boost amount BST of the waveform equalization circuit, this method is not preferable because it takes extra time. Therefore, if the measured jitter value becomes equal to or less than the predetermined set value JH at the time when the jitter measurement is completed at five jitter measurement points, the minimum jitter search is terminated, thereby shortening the algorithm. be able to.

FIG. 8 shows a flowchart of the minimum jitter search. The same steps as those included in the flowchart for describing the minimum jitter area searching method according to the first embodiment described above with reference to FIG. 5 are denoted by the same reference numerals. Detailed description of these steps will be omitted.

The difference from the flowchart for explaining the minimum jitter area searching method according to the first embodiment described above with reference to FIG. 5 is that instead of step 509, five jitter measurement points J4, J5, J6, J7 and J8 are used. Step 901 is performed to determine whether or not all the jitter values measured in step (1) are equal to or less than a predetermined set value JH indicating the jitter detection sensitivity. Five jitter measurement points J4, J5, J6,
If it is determined that all of the jitter values measured in J7 and J8 are not less than or equal to the predetermined set value JH corresponding to the jitter detection sensitivity (NO in step 901), the process returns to step 505. Five jitter measurement points J4, J5, J6,
When it is determined that all the jitter values measured in J7 and J8 are equal to or less than a predetermined set value JH representing the sensitivity of detecting jitter (YES in step 901), five jitter measurement points J4, J5, J6. , J7 and J8, determine the jitter measurement point at which the measured jitter is minimum, and set the equivalent amount, ie, the cutoff frequency FC and the boost value BST, corresponding to the jitter measurement point at which the measured jitter is minimum (step 510). ).

The predetermined set value JH can be set based on the jitter detection sensitivity described above. By terminating the minimum jitter search under a specific convergence condition, the search time can be reduced.

FIG. 9 is a block diagram for explaining the configuration of another optical disk device 200 according to the first embodiment. The same components as those included in the optical disk device 100 described above with reference to FIG. 1 are denoted by the same reference numerals. A detailed description of these components will be omitted.

Referring to FIG. 9, as another configuration for realizing a method for determining the optimal combination of variables X and Y that minimizes jitter, the group delay amount of each frequency band of waveform equalizing circuit 4, that is, The group delay amount in the frequency band (high band) and the group delay amount in the low frequency band (low band) are variable, and the group delay amount in the high frequency band (high band) and the low frequency band (low band) A configuration for realizing a method of determining an optimal combination with the group delay amount in the following will be described.

In order to describe the minimum jitter searching method executed by the minimum value jitter searching unit 6A included in the optical disk device 200, first, the relationship between the group delay amount and the jitter will be described.

When performing waveform equalization, the amount of group delay defined by the change in phase with respect to frequency (the unit of the amount of group delay is time) is set to a relatively lower side of the frequency band of the signal to be waveform-equalized. It includes a corresponding low band group delay GDL and a relatively high band corresponding high group delay GDH. The low band group delay amount GDL and the high band group delay amount GDH are configured to be variable. The group delay amount representing the group delay characteristic is
In the case of a multi-stage filter, it can be determined by changing the characteristics of any one of the filter sections so that desired characteristics can be obtained.
In the case of using a filter, the group delay characteristic can be determined by changing each tap coefficient.

FIG. 10 shows the group delay characteristic of the waveform equalizing circuit 4. The horizontal axis indicates frequency, the vertical axis (left) indicates gain (dotted line), and the vertical axis (right) indicates group delay. In the case of an ideal transmission path, the amount of group delay during waveform equalization is the same (flat) in all frequency bands. If a transmission path (including a circuit and a circuit element) has an element that distorts the group delay characteristic, a signal of higher quality can be obtained by varying the amount of group delay. Actually, any transmission line has distortion of the delay characteristic, and the deterioration of the reproduction signal quality due to the distortion appears in the jitter. Accordingly, there is an optimum delay amount for each of the high band group delay amount GDH and the low band group delay amount GDL of the waveform equalizing circuit, and the high band group delay amount GDH and the low band group delay amount GD
The optimal combination of L can be determined using the present invention.

FIG. 11 is a graph showing the relationship between the low-band delay amount, the high-band delay amount, and the jitter contour according to the first embodiment. When the points showing the same jitter are connected when the high band group delay amount GDH and the low band group delay amount GDL are varied, FIG.
As shown in FIG. 1, the jitter contour 205 drawn with the cutoff frequency FC and the boost amount BST described above with reference to FIGS.
A jitter characteristic diagram represented by a jitter contour line 205E can be drawn similarly to A to 205D.

Therefore, the cutoff frequency FC and the boost amount BST
As in the case of the above, the high band group delay amount GDH and the low band group delay amount GD
By determining the jitter minimum position on a characteristic plane having L as the horizontal axis and the vertical axis, the high-band group delay amount GDH and the low-band group delay amount GDL for realizing the optimum group delay characteristics can be calculated by the waveform equalizing circuit 4.
Can be set.

FIG. 12 is a block diagram for explaining the configuration of still another optical disk device 300 according to the first embodiment. Optical disk device 10 described above with reference to FIG.
The same components as those included in 0 are denoted by the same reference numerals. A detailed description of these components will be omitted.

Referring to FIG. 12, focus control for controlling a convergence state of a light beam to a predetermined state is a configuration for realizing a method for determining an optimum combination of variables X and Y that minimizes jitter. The target position (focus position, tracking position) of the tracking control means for controlling the light beam to scan on the track correctly is variable, and a method for determining an optimal combination of the focus position and the tracking position is realized. The configuration will be described.

The focus error signal FE generated by the preamplifier 3 is AD-converted via a balance circuit 2203 and input to the control device 7B. The tracking error signal TE generated by the preamplifier 3 is AD-converted via a balance circuit 2201 and input to the control device 7B. The input focus error signal FE is
The focus control unit 10 in B is phase-compensated and gain-compensated by a digital filter (not shown) and output to a focus drive unit (not shown) included in the optical head 2 via a DA converter (not shown).

The input tracking error signal TE is phase-compensated and gain-compensated by a digital filter (not shown) by a tracking control unit 12 in the control device 7B, and is passed through a DA converter (not shown). Are output to a tracking drive unit (not shown) included in the.

Here, the jitter input from the jitter detector 5 is added to the synthesizing circuit 11 receiving the output from the focus control unit 10 and the synthesizing circuit 2202 receiving the output from the tracking control unit 12 so as to minimize the jitter. The minimum offset, that is, the set values of the focus position and the tracking position are searched by the minimum value jitter search unit 6B.
By connecting points that show the same jitter when the focus position and the tracking position are changed,
As shown in FIG. 13, the jitter contour 2 drawn with the cutoff frequency FC and the boost amount BST described above with reference to FIGS.
A jitter characteristic diagram represented by a jitter contour line 205F can be drawn as in the case of 05A to 205D.

Therefore, the cutoff frequency FC and the boost amount BST
As in the case of (1), the optimum focus position and tracking position can be set by obtaining the minimum jitter position on a characteristic plane having the tracking position on the horizontal axis and the focus position on the vertical axis. In the above description, the case where a digital offset is applied to the signal from the focus control unit 10 and the signal from the tracking control unit 12 in the control device 7B has been described as a configuration in which the focus position and the tracking position are variable. 12, a balance circuit 22 for receiving a focus error signal FE as indicated by a dotted line.
03 and the output of the balance circuit 2201 that receives the tracking error signal TE.

FIG. 14 is a block diagram for explaining the configuration of still another optical disk device 400 according to the first embodiment. Optical disk device 10 described above with reference to FIG.
The same components as those included in 0 are denoted by the same reference numerals. A detailed description of these components will be omitted.

Referring to FIG. 14, as a configuration for realizing a method for determining the optimum combination of variables X and Y that minimizes jitter, the radial tilt of the optical disc 1 in the radial direction and the tangential tilt in the tangential direction are set. A description will be given of a configuration that can be corrected and realizes a method of determining an optimal combination of a correction value (adjustment value) of the radial tilt of the optical disc 1 and a correction value (adjustment value) of the tangential tilt.

FIG. 15 is a schematic diagram for explaining the tilt coordinate system according to the first embodiment. FIG. 15 shows the optical disk 1, a track 1802 on the optical disk 1, and a coordinate system. The radial direction of the disk is the X axis, the track scanning direction on the disk is the Y axis, and the direction perpendicular to the disk surface is the Z axis. The track scanning direction of the light beam is the Y-axis direction. Now, assuming that the light beam is irradiated along the z-axis, as shown in FIG. 15, when the light beam irradiation axis is inclined in the XZ plane, it is assumed that a radial tilt θr is generated and the light beam irradiation is performed. When the axis is inclined in the YZ plane, it is assumed that a tangential tilt θt has occurred.

FIG. 14 shows a configuration for changing the radial tilt θr and the tangential tilt θt shown in FIG. By providing the radial tilt control unit 1901 and the tangential tilt control unit 1902 in the control device 7C, the radial tilt θr and the tangential tilt θt can be changed. As a method of actually changing the radial tilt θr and the tangential tilt θt, the entire optical head 2 is mechanically tilted so that the radial tilt θr and the tangential tilt θ are changed.
t, or a method of optically changing the course of light to tilt the light beam irradiation axis to generate a radial tilt θr and a tangential tilt θt, but those methods are limited by these methods. is not. When one or both of the radial tilt θr and the tangential tilt θt change, the distribution of the light beam on the optical disc 1 is distorted, and thus the jitter is deteriorated. There is an optimum amount of tilt for both the radial tilt θr and the tangential tilt θt, and the optimum combination of the radial tilt θr and the tangential tilt θt can be determined using the present invention.

When the points showing the same jitter are connected when the radial tilt θr and the tangential tilt θt are varied, as shown in FIG. 16, the cutoff frequency FC and the boost amount BST described above with reference to FIGS. 2 and 4 are drawn. Jitter contour line 2 as well as jitter contour lines 205A to 205D
A jitter characteristic diagram represented by 05G can be drawn.

Therefore, the cutoff frequency FC and the boost amount BST
As in the case of the above, the optimum radial tilt θr and tangential tilt θt can be set by obtaining the minimum jitter position on a characteristic plane having the radial tilt θr as the horizontal axis and the tangential tilt θt as the vertical axis. . The actual tilt correction operation is generally performed by liquid crystal correction or a tilt actuator, but the present invention is not limited by the configuration of the tilt operation unit.

(Embodiment 2) Embodiment 2 is intended to adapt Embodiment 1 to apparatuses for reproducing various discs. The type of the loaded disk is determined, and the cutoff frequency FC is set as a variable X and the boost amount BST is set as a variable that can vary the jitter according to the determined type of the disk.
By obtaining an area where the jitter is minimum in each divided area obtained by dividing the initial area on the XY plane where is a variable Y, further dividing the divided area into small areas, and repeatedly obtaining an area where the jitter is minimum, This is a configuration for realizing a method for quickly determining the optimum combination of the variables X and Y for each type of loaded disc.

Here, in order to make the explanation easy to understand, an example of a configuration for realizing a method for determining an optimum combination of cutoff frequency FC and boost amount BST will be described. FIG. 17 is a block diagram for explaining the configuration of the optical disc device 500 according to the second embodiment. The same components as those included in the optical disk device 100 described above with reference to FIG. 1 are denoted by the same reference numerals. A detailed description of these components will be omitted.

The optical disk apparatus 100 includes an optical head 2 for irradiating a light beam emitted from a light source such as a semiconductor laser onto an optical disk 1 as an information carrier, and a reflected light from the optical disk 1 output from the optical head 2. A preamplifier 3 for amplifying the corresponding reproduced signal, a waveform equalizing circuit 4 for waveform equalizing the reproduced signal amplified by the preamplifier 3,
A binarizing circuit 13 for pulsing the reproduced signal whose waveform has been equalized by the waveform equalizing circuit 4, a jitter detecting circuit 5 for detecting jitter of the pulsed reproduced signal, and a reproduction signal of the reproduced signal amplified by the preamplifier 3. An amplitude detection circuit 8 for detecting the amplitude, and a control unit 7D for controlling the optical head 2 so that a light beam converged and irradiated from the optical head 2 onto the optical disk 1 is in an optimum convergence state.

The control section 7D includes a minimum value jitter search section 6D for searching for the minimum value of the jitter detected by the jitter detection circuit 5, and a focus position at which the amplitude of the reproduced signal detected by the amplitude detection circuit 8 becomes maximum. A maximum amplitude search section 9 for searching, a focus control section 10 for executing focus control so that a light beam emitted from the optical head 2 is in an optimum convergence state on the optical disk 1, and a light emitted from the optical head 2 A tracking control unit 12 that performs tracking control so that the beam scans a track on the optical disc 1 correctly; and a signal from the maximum amplitude search unit 9 is a focus control signal from the focus control unit 10 and tracking from the tracking control unit 10. A synthesizing circuit 11 for synthesizing with the control signal. The control unit 7D further includes a disk determination unit 20.

The disc discriminating section 20 measures the amplitude of a signal corresponding to the reflected beam of the optical disc 1 obtained from the amplitude detecting circuit 8, ie, the RF signal amplitude, and compares the measured RF signal with a predetermined judgment level. Then, the type of the loaded optical disc 1 is determined, and the processing of the minimum jitter area search unit 6D is switched according to the type of the disc.

The present invention is not limited to the type of the disc to be reproduced, but at least two or more types of reflectance, density,
This is for an optical disk device that plays disks of different capacities. Therefore, in order to make the explanation easy to understand, for example, it is assumed that a disc of the type shown in (Table 1) is reproduced.

[0110]

[Table 1] Before the focus control unit 10 is operated, the optical head 2 is moved to the optical disk 1 according to the difference in the reflectance of the mounted disk.
The optical beam spot is
When the image is focused on above, a focus error signal and an RF signal are output as shown in FIG.

The amplitude detection circuit 8 processes the amplitude of this RF signal by envelope detection or the like, and inputs it to the control unit 7D as a digital value through, for example, an AD converter (not shown). The controller 7D compares the input RF amplitude with a predetermined discrimination level in a disc discriminating section 20 therein, and determines whether the disc loaded is a disc α, a disc β, a disc γ, or an unloaded disc. Determine whether it is. The discrimination result is input to the minimum value jitter searching unit 6D, and the search algorithm is switched according to the discrimination result.

Next, a discrimination algorithm for switching according to the discrimination result will be described with reference to FIGS. 19 (a), 19 (b) and 19 (c). 19 (a), 19 (b) and 19 (c), as in the first embodiment, the horizontal axis represents the cutoff frequency FC, and the vertical axis represents the boost amount BST. Boost amount BS
Based on the discrimination result of the disc discrimination unit 20, the initial area A in which the variable width of T is set to 8 steps is determined based on the jitter measurement point J.
The figure shows the divided areas corresponding to 0, J1, J2, J3, and J4.

If the disc discrimination section 20 discriminates the disc α, the disc α has a channel clock of 4M
Hz and the lowest playback speed among the three types of discs. Therefore, the initial region A is set to 1 /
In the area Z of No. 4, divided areas Z1, Z2, Z3 and Z4 in which the boost amount BST is divided by two are created. J1, J2, and J3 are used as jitter measurement points for measuring jitter in these four divided areas Z1, Z2, Z3, and Z4.
And J4 are determined. Next, jitter was measured at these four points, and the four regions Z1, Z2, Z3 and Z
The area where the jitter is the smallest among the four is determined by comparison, but if all four points have the same measured value, the minimum jitter area cannot be determined.

Therefore, J corresponding to the center of the four regions (center)
The jitter at J0 is also measured with 0 as the jitter measurement point, and if the five measured values are the same, the cutoff frequency FC and the boost value BST at the jitter measurement point J0 are determined as the optimum values.

Assuming that the jitter characteristic in the area Z is as shown in FIG. 4, the minimum jitter position of the five representative jitter measurement points is J3, and the cut-off frequency F corresponding to J3.
By setting C and the boost amount BST, optimization of the frequency characteristics of the waveform equalization circuit 4 on the disk α is completed.

Similarly, when the disc discriminating section 20 discriminates the disc β, the disc β has a channel clock of 27 MHz, which is the second reproduction speed among the three kinds of discs. Therefore, as shown in FIG.
Are divided for every two values of the boost amount BST in a quarter Y, which is a little higher than the center of the cutoff frequency FC, to form divided areas Y1, Y2, Y3 and Y4. In these four divided areas Y1, Y2, Y3, and Y4, four points J1, J2, J3, and J4 are determined as jitter measurement points. Next, the jitter is measured at these four points, and the area where the jitter is the smallest among the four areas is compared and determined. If all the four points have the same measured value, the minimum jitter area cannot be determined.

Therefore, J corresponding to the center of the four regions is considered.
The jitter at J0 is also measured with 0 as the jitter measurement point. If the five measured values are the same, the cutoff frequency FC and the boost value BST at the jitter measurement point J0 are determined as the optimum values.

Assuming that the minimum jitter position of the five jitter measurement points is the jitter measurement point J3, by setting the cutoff frequency FC and the boost amount BST corresponding to the jitter measurement point J3, the waveform equalization circuit 4 of the disk β Optimization of the frequency characteristics is completed.

Similarly, when the disc discriminating section 20 discriminates the disc γ, the disc γ has a channel clock of 29 MHz, which is the fastest reproduction speed among the three types of discs. Therefore, in the initial region A, in the region X of the highest quarter of the cutoff frequency FC, the value of the boost amount BST is 2
Creates divided areas X1, X2, X3 and X4. These four divided areas X1, X2, X3 and X4
In the above, four points J1, J2, J3, and J4 are determined as jitter measurement points. Next, the jitter is measured at these four points, and the area where the jitter is the smallest among the four areas is compared and determined. If all the four points have the same measured value, the minimum jitter area cannot be determined.

Therefore, J corresponding to the center of the four regions is considered.
The jitter at J0 is also measured using 0 as a representative point, and if the five measured values are the same, the cutoff frequency FC and the boost value BST at the measurement point J0 are determined as optimal values.

Assuming that the minimum jitter position of the five jitter measurement points is the jitter measurement point J2, the cut-off frequency FC and the boost amount BST corresponding to the jitter measurement point J2 are set, so that the waveform equalization circuit 4 on the disk γ is controlled. Optimization of the frequency characteristics is completed. Control unit 7D of the second embodiment
FIG. 20 shows the flow of the processing in.

The disc discriminating section 20 discriminates the type of the disc (step 1201). When the disc discrimination unit 20 discriminates the disc α, the initial area A is divided into two areas Z1 and Z2 in which the boost amount BST is divided into two in an area Z on the lower side of the cutoff frequency FC.
Z3 and Z4 are created (step 1202). When the disc discriminating section 20 discriminates the disc β,
The initial region A is set to 1 slightly higher than the center of the cutoff frequency FC.
In the area Y of / 4, divided areas Y1, Y2, Y3, and Y4 divided for each value of the boost amount BST of 2 are created (step 1203). If the disc discrimination unit 20 discriminates the disc as γ, the initial area A
In the region X on the highest quarter of C, divided regions X1, X2, X3 and X4 are divided by the value 2 of the boost amount BST (step 1204).

A jitter measurement point for measuring jitter in the four divided areas is determined, and an equivalent amount (cutoff frequency and boost amount) is set (step 1205). Jitter is measured at five jitter measurement points J0, J1, J2, J3 and J4 (step 1206). The jitter measuring point at which the measured jitter is minimum among the five jitter measuring points J0, J1, J2, J3 and J4 is determined (step 1207).

It is determined whether the width between the jitter measurement point J0 and the jitter measurement points J2 and J3 is 1 and the minimum unit set width is reached (step 1208). If it is determined that the width between the jitter measurement point J0 and the jitter measurement points J2 and J3 is not equal to the minimum unit set width (NO in Step 1208), the process returns to Step 1205. If it is determined that the width between the jitter measurement point J0 and the jitter measurement points J2 and J3 is the minimum unit set width (YES in step 1208), the five jitter measurement points J
The jitter measuring point at which the measured jitter is minimum among 0, J1, J2, J3, and J4 is determined, and the equivalent amount corresponding to the jitter measuring point at which the measured jitter is minimum, that is, the cutoff frequency FC and the boost value BST are determined. Set (Step 12
09).

As described above, the minimum jitter area can be specified very quickly by limiting the divided area from which the search is started in accordance with the type of the disc determined by the disc discriminating section 20, and the optimum waveform equalizer can be specified. Settings can be made.

As described in the first embodiment, in addition to the cutoff frequency FC and the boost amount BST, the variable XY that can vary the jitter, the group delay amount in the high band and the low band, the focus position and the tracking position, and the radial position Although it is possible to realize a configuration adapted to tilt and tangential tilt, the configuration and method are the same, and a description thereof will be omitted.

(Embodiment 3) Embodiment 3 is different from Embodiment 1 in that a device capable of changing the reproduction speed of a disc, for example, C
This is for adapting to an AV playback device. When the apparatus is started, the XY plane with the cutoff frequency FC as a variable X and the boost amount BST as a variable Y is set as a variable that can vary the jitter based on the address information obtained from the disk or the data frequency obtained from the disk. Limiting the area within a predetermined range, finding the area where the jitter is minimized in each divided area of the initial area, further dividing the divided area into smaller areas, and repeatedly finding the area where the jitter is the smallest To find the optimal combination of variables X and Y,
When the rotation speed of the optical disk is dynamically switched between the inner circumference and the outer circumference of the disk, a method for determining an optimum frequency characteristic of the waveform equalizer at each reproduction speed is realized.

Here, in order to make the explanation easy to understand, an example of a configuration for realizing a method for determining an optimum combination of the cutoff frequency FC and the boost amount BST will be described. FIG. 21 is a block diagram for explaining the configuration of the optical disc device 600 according to the third embodiment. The same components as those included in the optical disk device 100 described above with reference to FIG. 1 are denoted by the same reference numerals. A detailed description of these components will be omitted.

The optical disk device 600 includes an optical head 2 for converging and irradiating a light beam emitted from a light source such as a semiconductor laser onto an optical disk 1 serving as an information carrier, and a reflected light from the optical disk 1 output from the optical head 2. A preamplifier 3 for amplifying the corresponding reproduced signal, a waveform equalizing circuit 4 for waveform equalizing the reproduced signal amplified by the preamplifier 3,
A binarizing circuit 13 for pulsing the reproduced signal whose waveform has been equalized by the waveform equalizing circuit 4, a jitter detecting circuit 5 for detecting jitter of the pulsed reproduced signal, and a reproduction signal of the reproduced signal amplified by the preamplifier 3. An amplitude detection circuit 8 for detecting the amplitude, and a control unit 7E for controlling the optical head 2 so that the light beam converged and irradiated from the optical head 2 onto the optical disc 1 is in an optimum convergence state.

The control unit 7E includes a minimum value jitter search unit 6E for searching for the minimum value of the jitter detected by the jitter detection circuit 5, and a focus position at which the amplitude of the reproduction signal detected by the amplitude detection circuit 8 becomes maximum. A maximum amplitude search unit 9 for searching, a focus control unit 10 for executing focus control so that a light beam emitted from the optical head 2 is in an optimum convergence state on the optical disk 1, and a light emitted from the optical head 2 A tracking control unit 12 that performs tracking control so that the beam scans a track on the optical disc 1 correctly; and a signal from the maximum amplitude search unit 9 is a focus control signal from the focus control unit 10 and tracking from the tracking control unit 10. A synthesizing circuit 11 for synthesizing with the control signal.

The optical disc device 100 includes a binarizing circuit 13
And a reproduction speed detection unit 30 for detecting a reproduction speed of the reproduction signal based on the output of the reproduction signal. The playback speed detection unit 30
The period (frequency) of the data signal input from the binarization circuit 13 is detected, and the reproduction speed of the reproduction signal on the track on the optical disk 1 on which the light beam is scanning is calculated. Specifically, there are various calculation methods. For example, the cycle of the longest mark in the recording format is detected. Alternatively, the playback speed of the playback signal can be uniquely calculated by detecting the cycle of the shortest mark. Data representing the calculated reproduction speed is input to the control device 7E. The control device 7E switches the processing of the minimum jitter searching unit 6E based on the data representing the input reproduction speed.

[0132] In the case of CAV playback, the playback speed changes by a maximum of about 2.5 times between access between the inner circumference and the outer circumference. For example, if the inner channel clock is 27 MHz, the outer channel clock is about 27 × 2.5 = 57.5 MHz. Depending on the setting of the optical disk device, for example, 1 × speed reproduction for audio reproduction of a CD, and 40 × speed (16 × inner speed) for reading a ROM according to the use condition.
By switching between the audio reproduction mode and the ROM reading mode, there is a case where the change is 16 times. Therefore, since the signal frequency also varies by the magnification, the setting range of the cutoff frequency FC in the waveform equalizer can be determined according to the reproduction speed. Therefore, since the area defined by the cutoff frequency FC and the boost amount BST of the waveform equalizer can be limited according to the data representing the reproduction speed, the cutoff frequency FC and the boost amount BST can be quickly set. .

FIGS. 22 (a), 22 (b) and 22
(C) is a diagram for explaining jitter measurement points in the minimum jitter area search method according to the third embodiment. FIG.
(A), FIG. 22 (b) and FIG. 22 (c), as in the first embodiment, the horizontal axis represents the cutoff frequency FC and the vertical axis represents the boost amount BST. The initial area A in which the variable width of the BST is set to 8 steps is shown based on the detection result of the reproduction speed detection circuit 30 and is divided corresponding to the jitter measurement points J0, J1, J2, J3, and J4. It is. The inner circumference of the disk (channel clock 27MH)
z) Switching of the algorithm for optimally setting the waveform equalizer at three locations, that is, the middle frequency (channel clock 43 MHz) and the outer circumference (channel clock 57.5 MHz) will be described.

When the reproduction speed detection section 30 detects a reproduction speed of, for example, a channel clock of 27 MHz and a maximum frequency of 4.5 MHz, it can be determined that the reproduction speed is lower at the inner periphery. As a result, divided regions Z1, Z2, Z3, and Z4 in which the boost amount BST is divided by two in the region Z on the lower side of the cutoff frequency FC from the initial region A are formed. In these four areas Z1, Z2, Z3 and Z4, four points J1, J2, J3 and J4 are determined as jitter measurement points. Next, the jitter is measured at these four points, and the area where the jitter is the smallest among the four areas is compared and determined. If all the four points have the same measured value, the minimum jitter area cannot be determined.

Therefore, J corresponding to the center of the four regions (center)
The jitter at J0 is also measured with 0 as the jitter measurement point. If the above five measured values are the same, the cutoff frequency FC and the boost value BST at the jitter measurement point J0 are determined as optimal values.

Assuming that the jitter characteristic in the region Z is as shown in FIG. 4, the minimum jitter position of the five representative jitter measurement points is J3, and the cut-off frequency F corresponding to J3.
By setting C and the boost amount BST, optimization of the frequency characteristics of the waveform equalization circuit 4 on the inner circumference is completed.

Similarly, in the reproduction speed detector 30, for example, a channel clock of 43 MHz and a maximum frequency of 7.1 MHz
When the playback speed is detected as z, it can be determined that the playback speed is the second middle playback speed. Therefore, as shown in FIG. 22B, the initial area A is set to 1 / on the side slightly higher than the center of the cutoff frequency FC.
In the region Y of No. 4, divided regions Y1, Y2, Y3, and Y4 are formed by dividing the boost amount BST by two. In these four divided areas Y1, Y2, Y3, and Y4, four points J1, J2, J3, and J4 are determined as jitter measurement points. Next, the jitter was measured at these four points,
The area having the smallest jitter among the four areas is compared and determined. If all four points have the same measured value,
The minimum jitter area cannot be determined.

Therefore, J corresponding to the center of the four regions (center)
The jitter at J0 is also measured with 0 as the jitter measurement point. If the five measured values are the same, the cutoff frequency FC and the boost value BST at the jitter measurement point J0 are determined as the optimum values.

Assuming that the minimum jitter position of the five jitter measurement points is the jitter measurement point J3, by setting the cutoff frequency FC and the boost amount BST corresponding to the jitter measurement point J3, the waveform equalization circuit 4 in the middle circumference is set. Optimization of the frequency characteristics is completed.

Similarly, in the reproduction speed detecting section 30, for example, a channel clock of 67.5 MHz and a maximum frequency of 11.
When it is determined that the reproduction speed is 25 MHz, it can be determined that the reproduction speed is the fastest outer peripheral reproduction speed. As a result, divided regions X1, X2, which divide the initial region A by a value 2 of the boost amount BST in a region X on the highest side of the cutoff frequency FC.
Make X3 and X4. These four divided areas X1, X
2, J1 as the jitter measurement point at X3 and X4,
Four points J2, J3 and J4 are determined. Next, the jitter is measured at these four points, and the area where the jitter is the smallest among the four areas is compared and determined. If all the four points have the same measured value, the minimum jitter area cannot be determined.

Therefore, J corresponding to the center of the four regions is considered.
The jitter at J0 is also measured using 0 as a representative point, and if the five measured values are the same, the cutoff frequency FC and the boost value BST at the measurement point J0 are determined as optimal values.

Assuming that the jitter minimum position of the above five jitter measurement points is the jitter measurement point J2, the cutoff frequency FC and the boost amount BST corresponding to the jitter measurement point J2 are set, so that the frequency of the waveform equalization circuit 4 on the outer periphery is set. Optimization of the characteristics is completed. FIG. 23 shows the flow of processing in the control device 7E of the third embodiment.

The reproduction speed detection circuit 30 detects the reproduction speed of the reproduction signal. (Step 1501). If the reproduction speed detection circuit 30 determines that the reproduction speed is low at the inner periphery, the boost amount BST is divided into two in the initial region A in the region の on the lower side of the cutoff frequency FC. Create regions Z1, Z2, Z3 and Z4 (step 1
502). If the reproduction speed detection circuit 30 determines that the reproduction speed is the second reproduction speed in the middle circumference, the initial region A is set to the value 2 of the boost amount BST in the region Y which is slightly higher than the center of the cutoff frequency FC. Divided area Y divided for each
1, Y2, Y3 and Y4 are made (step 150).
3). When the reproduction speed detection circuit 30 determines that the reproduction speed is the fastest reproduction speed on the outer periphery, the initial region A is set to the cutoff frequency F
In a region X on the highest quarter of C, divided regions X1, X2, X3 and X4 are divided by the value 2 of the boost amount BST (step 1504).

Jitter measurement points for measuring jitter in the four divided areas are determined, and the equivalent amount (boost amount is set (step 1505). Five jitter measurement points J0 and J
The jitter is measured at 1, J2, J3 and J4 (step 1506). 5 jitter measurement points J0, J
The jitter measuring point at which the measured jitter is minimum among 1, J2, J3 and J4 is determined (step 1507).

It is determined whether the width between the jitter measurement point J0 and the jitter measurement points J2 and J3 is 1 and the minimum unit set width is reached (step 1508). If it is determined that the width between the jitter measurement point J0 and the jitter measurement points J2 and J3 is not the minimum unit set width (NO in Step 1508), the process returns to Step 1205. If it is determined that the width between the jitter measurement point J0 and the jitter measurement points J2 and J3 is the minimum unit set width (YES in step 1508), the five jitter measurement points J
The jitter measuring point at which the measured jitter is minimum among 0, J1, J2, J3, and J4 is determined, and the equivalent amount corresponding to the jitter measuring point at which the measured jitter is minimum, that is, the cutoff frequency FC and the boost value BST are determined. Set (Step 15
09).

As described above, based on the reproduction speed detected by the reproduction speed detection circuit 30, by limiting the initial region where the search is started, the minimum jitter region can be specified very quickly.
The optimum waveform equalizer can be set. In the above description, an example has been described in which three settings of the inner circumference, the middle circumference, and the outer circumference are set. However, the configuration is such that the constantly changing reproduction speed is constantly detected and the set value of the waveform equalizer is updated. May be.

As described in the first embodiment, in addition to the cut-off frequency FC and the boost amount BST, the variable XY that can vary the jitter, the group delay amount in the high band and the low band, the focus position and the tracking position, and the radial position Although it is possible to realize a configuration in which the tilt correction amount and the tangential tilt correction amount are adapted, the configuration and method are the same, and a description thereof will be omitted.

Although the reproduction speed detected by the reproduction speed detection circuit 30 has been described with a configuration in which the period (frequency) of the reproduction signal is detected, for example, the radial position is calculated based on the address information recorded on the optical disk 1. Then, the reproduction speed may be detected from the radial position. The reproduction speed can also be detected by a target rotation number of the optical disk 1 by a command or the like, or by the FG of a motor for actually rotating the optical disk 1.

Further, in the third embodiment, the inner circumference once,
Once the optimum set value in the middle, outer, or each playback speed mode is determined, the set value is stored in a memory such as the control unit 7E and stored in the memory each time a seek or speed switching command comes. Values can be loaded and set in the waveform equalizer. When the reproduction is not possible, by using the minimum jitter area search method again to perform the resetting, the performance of the waveform equalization circuit can be further improved.

(Embodiment 4) FIG. 24 shows Embodiment 4 of the present invention.
3 is a block diagram for explaining a configuration of a PLL circuit 700 according to the first embodiment. FIG. Optical disk device 1 described above with reference to FIG.
The same components as those included in 00 are denoted by the same reference numerals. A detailed description of these components will be omitted.

In the fourth embodiment, the first embodiment is applied to a PLL circuit for removing a circuit offset of data slice balance. The PLL circuit 700 includes a reference signal generation circuit 2600 that generates a monotone signal for removing a circuit offset, a binarization circuit 13 for binarizing a monotone signal,
A data slice balance setting unit 2601 for setting the binarization circuit 13 so that the center of the signal amplitude of the monotone signal can be binarized, a clock signal generation circuit 2605 for generating a clock signal, and the binarization circuit 13 A phase comparison unit 2606 that compares the phases of the binarized signal and the clock signal generated by the clock signal generation circuit 2605 and outputs a phase error signal; a jitter detection circuit 5 that integrates the phase error signal; Charge pump circuit 2 for averaging the phase error signal output by comparison section 2606
602 and a low-pass filter (LPF) 26 that removes an AC component of the output of the charge pump circuit 2602 and supplies a stable oscillation reference voltage to the clock signal generation circuit 2605.
04, a phase adjustment unit 2603 for adjusting the phase shift of the phase error signal, and a minimum value jitter search unit 6F.

The data slice balance setting section 2601 will be described. In order to reproduce information from marks or pits recorded on an optical disk, it is necessary to accurately read the length of the recorded marks or pits. For this purpose, it is desirable that the center of the amplitude of the reproduced signal be a data slice level for binarization. This is because the length of the mark or pit can be accurately read. The data slice level can be feedback-controlled by integrating positive and negative pulses of the binarized data binarized by the binarization circuit 13. However, even if the data slice level is feedback-controlled, the binarization circuit 13 generally has a circuit offset, so that the feedback control alone is not sufficient. Therefore, it is necessary to finely adjust the data slice level by the data slice balance setting unit 2601.

The phase adjustment unit 2603 will be described. The clock generation circuit 2605 is a voltage-controlled oscillation circuit that generates a clock signal that changes according to an oscillation reference voltage (control voltage). The oscillation reference voltage (control voltage) received by the clock generation circuit 2605 compares the phase of the signal binarized by the binarization circuit 13 with the phase of the clock signal generated by the clock signal generation circuit 2605, and compares the phase of the signal with the phase comparison unit 26.
The phase error signal output from 06 is averaged by a charge pump circuit 2602 and passed through a low-pass filter 2604 for stabilizing the loop characteristics of the PLL, whereby the phase error signal is input to a clock generation circuit 2605.

Charge pump circuit 2602 integrates and averages the phase error signal. Charge pump circuit 2602
Increases or decreases the charge current based on the advance or delay of the clock signal generated by the clock signal generation circuit 2605 with respect to the signal binarized by the binarization circuit 13. However, the charge pump circuit 26
02, the characteristics of a transistor provided in an integrated circuit included in the integrated circuit 02 do not have a symmetrical characteristic of sinking and discharging characteristics of the output current output from the charge pump circuit 2602.
The output current output from 2 becomes unbalanced. When the output current output from the charge pump circuit 2602 becomes unbalanced, the oscillation reference voltage (control voltage) supplied to the clock generation circuit 2605 changes, so that the clock signal generated by the clock signal generation circuit 2605 and the binary signal A phase shift occurs between the signal binarized by the digitizing circuit 13.

The phase adjustment section 2603 adjusts such a phase shift. Specifically, the phase adjustment unit 2603 changes the current balance in the output stage included in the charge pump circuit 2602, so that the clock signal generated by the clock signal generation circuit 2605 and the binarization circuit 13 binarize the clock signal. The phase shift with respect to the signal can be adjusted. The phase adjustment unit 2603 may adjust such a phase shift by changing the current balance using an A / D converter included in the phase adjustment unit 2603.

When such a phase shift occurs, the jitter of the reproduced signal increases. Therefore, it is necessary to search for the optimum amount of phase adjustment while monitoring the jitter of the reproduced signal. As described above, when a phase shift occurs because the phase adjustment unit 2603 is not optimally set, the jitter of the reproduced signal increases. When trying to optimally set the data slice balance while monitoring the jitter of the reproduced signal, it may be difficult to search for the optimum data slice balance because the degree of change of the jitter with respect to the data slice balance is small. is there.

Therefore, while monitoring the jitter of the reproduced signal, the optimum value between the data slice balance amount set by the data slice balance setting unit 2601 and the phase adjustment amount adjusted by the phase adjustment unit 2603 so that the jitter is minimized. Search for combinations.

FIG. 25 is a graph showing the relationship between the phase adjustment amount, the data slice balance amount, and the jitter contour according to the fourth embodiment. When points indicating the same jitter are connected when the phase adjustment amount and the data slice balance amount are varied, as shown in FIG. 25, the jitter contour line 205A drawn with the cutoff frequency FC and the boost amount BST described above with reference to FIGS. Jitter contour 205 as well as 205D
A jitter characteristic diagram represented by H can be drawn.

Therefore, the cutoff frequency FC and the boost amount BST
In the same manner as in the above case, the optimum phase adjustment amount and data slice balance amount can be set by obtaining the minimum jitter position on a characteristic plane having the phase adjustment amount as the horizontal axis and the data slice balance amount as the vertical axis. . The search method for finding the minimum jitter position is the same as the search method for finding the minimum jitter position described in Embodiment 1 except that the variable X and the variable Y are used as the phase adjustment amount and the data slice balance amount, respectively. Description is omitted.

FIG. 26 is a flowchart for explaining the minimum jitter area searching method according to the fourth embodiment. Five jitter measurement points are set in the initial area (step 2801). An equivalent amount, that is, a phase adjustment amount and a data slice balance amount corresponding to any of the jitter measurement points are set (step 2802). The jitter is measured based on the set phase adjustment amount and data slice balance amount (step 2803). It is determined whether or not jitter has been measured at all of the five jitter measurement points (step 2804). If it is determined that the jitter has not been measured at all of the five jitter measurement points (NO in step 2804), at the jitter measurement point of which the jitter has not yet been measured among the five jitter measurement points Step 28 to measure jitter
Return to 02. When it is determined that the jitter has been measured at all of the five jitter measurement points (YES in step 2804), the jitter measurement point having the smallest measured jitter among the five jitter measurement points is determined. (Step 2805).

[0161] Five jitter measurement points are set in the divided area corresponding to the jitter measurement point at which the measured jitter is the minimum (step 2806). An equivalent amount corresponding to any one of the five jitter measurement points, that is, a phase adjustment amount and a data slice balance amount are set, and the jitter is measured based on the set phase adjustment amount and data slice balance amount (step 2807). It is determined whether or not jitter has been measured at all of the five jitter measurement points (step 2808). If it is determined that the jitter has not been measured at all of the five jitter measurement points (NO in step 2808), at the jitter measurement point at which the jitter has not yet been measured among the five jitter measurement points Step 280 to measure jitter
Return to 6. If it is determined that the jitter has been measured at all of the five jitter measurement points (YES in step 2808), all the jitter values measured at the five jitter measurement points indicate the jitter detection sensitivity. It is determined whether the value is equal to or less than a predetermined set value JH (step 28).
09). If it is determined that all the jitter values measured at the five jitter measurement points are not less than or equal to the predetermined set value JH corresponding to the jitter detection sensitivity (N at step 2809)
O), returning to step 2805; If it is determined that all the jitter values measured at the five jitter measurement points are equal to or less than a predetermined set value JH representing the jitter detection sensitivity (YES in step 2809), the measurement is performed among the five jitter measurement points. The jitter measurement point at which the measured jitter is minimum is determined, and the phase adjustment amount and the data slice balance amount corresponding to the jitter measurement point at which the measured jitter is minimum are set (step 2810).

[0162]

As described above, according to the present invention, in an optical disk apparatus which supports various types of optical disks and switches the reproduction speed in multiple steps, the start-up time and the readout time can be shortened with high reliability and high speed. An optical disk device can be provided.

Further, according to the present invention, it is possible to provide an optical disk apparatus and a PLL circuit capable of quickly and efficiently obtaining a combination of parameters that minimizes jitter.

[Brief description of the drawings]

FIG. 1 is a block diagram for explaining a configuration of an optical disc device according to a first embodiment;

FIG. 2 is a graph showing a relationship between a cutoff frequency, a boost amount, and a jitter contour according to the first embodiment;

FIG. 3 is a diagram for explaining a minimum jitter area search method according to the first embodiment;

FIG. 4 is a graph for explaining a minimum jitter area according to the first embodiment;

FIG. 5 is a flowchart illustrating a minimum jitter area search method according to the first embodiment;

FIG. 6 is a view for explaining jitter measurement points in the minimum jitter area searching method according to the first embodiment;

FIG. 7 is a view for explaining a measurement order of jitter measurement points in the minimum jitter area searching method according to the first embodiment;

FIG. 8 is a flowchart illustrating another minimum jitter area searching method according to the first embodiment;

FIG. 9 is a block diagram for explaining a configuration of another optical disk device according to the first embodiment;

FIG. 10 is a group delay characteristic diagram of the waveform equalization circuit according to the first embodiment;

FIG. 11 is a graph showing a relationship between a low-band delay amount, a high-band delay amount, and a jitter contour according to the first embodiment;

FIG. 12 is a block diagram for explaining a configuration of still another optical disk device according to the first embodiment;

FIG. 13 is a graph showing a relationship between a tracking control target position, a focus position, and a jitter contour according to the first embodiment.

FIG. 14 is a block diagram for explaining a configuration of still another optical disc device according to the first embodiment.

FIG. 15 is a schematic diagram for explaining a tilt coordinate system according to the first embodiment.

FIG. 16 is a graph showing the relationship between radial tilt, tangential tilt, and jitter contour according to the first embodiment.

FIG. 17 is a block diagram illustrating a configuration of an optical disc device according to a second embodiment;

FIG. 18 is a graph for explaining the operation of the disk discriminating unit of the optical disk device according to the second embodiment.

FIG. 19 is a view for explaining jitter measurement points in the minimum jitter area searching method according to the second embodiment.

FIG. 20 is a flowchart illustrating a minimum jitter area searching method according to the second embodiment;

FIG. 21 is a block diagram illustrating a configuration of an optical disc device according to a third embodiment;

FIG. 22 is a view for explaining a jitter measurement point in the minimum jitter area searching method according to the third embodiment.

FIG. 23 is a flowchart illustrating a minimum jitter area search method according to the third embodiment;

FIG. 24 is a block diagram illustrating a configuration of a PLL circuit according to a fourth embodiment.

FIG. 25 is a graph showing a relationship between a phase adjustment amount, a data slice balance amount, and a jitter contour according to the fourth embodiment.

FIG. 26 is a flowchart illustrating a minimum jitter area searching method according to the fourth embodiment;

FIG. 27 is a graph showing gain and noise frequency characteristics of the waveform equalizing means.

FIG. 28 is a graph showing jitter characteristics with respect to a focus position.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Optical disk 2 Optical head 3 Preamplifier 4 Waveform equalization circuit 5 Jitter detection part 6 Minimum value jitter search part 7 Controller 8 Amplitude detection part 9 Maximum amplitude search part 10 Focus control part 11 Synthesis circuit 12 Tracking control part 13 Binarization circuit 20 disc discrimination unit 30 playback speed detection unit

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H03L 7/093 H03L 7/08 M (72) Inventor Katsuya Watanabe 1006 Kadoma, Kazuma, Kazuma, Osaka Matsushita Electric Industrial In-house F-term (reference) 5D044 BC02 CC06 FG02 FG05 FG06 FG11 FG16 GM12 GM18 5D090 AA01 CC04 DD03 EE17 FF01 FF41 5D118 AA14 BA01 BF02 CA04 CA11 CA13 CC12 CD08 5J106 AA04 BB03 BB04 CC03 CC15 CC02 CC59 CC15 CC02

Claims (20)

[Claims] 1. An optical disc device for optically reproducing information recorded on an information carrier by a light beam emitted from a light source, comprising: a converging means for converging and irradiating the light beam; A light detection unit that generates a reproduction signal corresponding to the reflected light or the transmitted light of the beam; a waveform equalization unit that changes a frequency characteristic of the reproduction signal generated by the light detection unit; A jitter measuring means for measuring the jitter of the output signal; and a jitter measuring means for changing the jitter measured by the jitter measuring means in an initial area on an XY plane defined by two variables, a variable X and a variable Y. Jitter minimum value searching means for obtaining a minimum value, wherein the jitter minimum value searching means comprises a plurality of first divisions having the same shape in the initial region. Into a plurality of first divided regions, each of which is located at a center of gravity of the plurality of first divided regions.
One of the plurality of first divided regions where the minimum jitter is measured among the jitters measured at the jitter measurement point is searched, and the minimum jitter value searching means searches the plurality of first divided regions.
The one of the divided regions is divided into a plurality of second divided regions having the same shape as each other, and jitters measured at a plurality of second jitter measurement points respectively located at the centers of gravity of the plurality of second divided regions are determined. One of the plurality of second divided regions in which the minimum jitter is measured is searched, and the plurality of second jitter measurement points included in the one of the searched plurality of second divided regions are searched. An optical disc apparatus that determines an optimal combination of the variable X and the variable Y corresponding to one of the following. 2. The minimum jitter value searching means divides the initial area into four first divided areas having an equal square shape and four first divided areas respectively located at the centers of gravity of the four first divided areas. One of the four first divided areas where the minimum jitter is measured among the jitters measured at one jitter measurement point is searched, and the jitter minimum value searching means searches the four first divided areas.
The one of the divided regions is divided into four second divided regions having the same shape as each other, and jitters measured at four second jitter measuring points respectively located at the centers of gravity of the four second divided regions are determined. The above 4 where the minimum jitter was measured
2. The optical disk device according to claim 1, wherein one of the second divided areas is searched. 3. The optical disc apparatus according to claim 1, wherein when the value of the jitter measured by the jitter measuring means is equal to or less than a predetermined value, the minimum jitter value searching means ends the searching operation. 4. When the jitter measuring means cannot measure the jitter in a certain area, the jitter measuring means omits the measurement in the area in which the jitter could not be measured. The optical disk device according to claim 1, wherein the optical disk device searches for a jitter area. 5. The optical disk device according to claim 1, wherein the variable X includes a cutoff frequency, and the variable Y includes a boost amount. 6. The optical disk device according to claim 1, wherein the variable X includes a high-frequency delay amount, and the variable Y includes a low-frequency delay amount. 7. A focus control means for controlling said convergence means so that said light beam is brought into a predetermined convergence state with respect to said record carrier, and such that said light beam scans a track on said record carrier correctly. The optical disk device according to claim 1, further comprising: a tracking control unit that controls the convergence unit, wherein the variable X includes a tracking position, and the variable Y includes a focus position. 8. A radial tilt adjusting means for adjusting a tilt of the light beam in a radial direction with respect to the record carrier, and a tangential tilt adjusting means for adjusting a tilt of the light beam in a tangential direction with respect to the record carrier. The optical disc device according to claim 1, wherein the variable X includes a radial tilt, and the variable Y includes a tangential tilt. 9. An optical disk device for optically reproducing information recorded on an information carrier by a light beam emitted from a light source, comprising: a converging means for converging and irradiating the light beam; A light detection unit that generates a reproduction signal corresponding to the reflected light or the transmitted light of the beam; a waveform equalization unit that changes a frequency characteristic of the reproduction signal generated by the light detection unit; A jitter measuring means for measuring the jitter of the output signal; and a jitter measuring means for changing the jitter measured by the jitter measuring means in an initial area on an XY plane defined by two variables, a variable X and a variable Y. A jitter minimum value searching means for determining a minimum value; and an information carrier determining means for determining a type of the information carrier. The initial area is divided into a plurality of first divided areas having the same shape as each other, and one of the plurality of first divided areas is selected based on the type of the information carrier determined by the information carrier determining means. The minimum jitter value searching means may select the plurality of first
The one of the divided regions is divided into a plurality of second divided regions having the same shape as each other, and a minimum of jitter measured at a plurality of jitter measurement points respectively located at the center of gravity of the plurality of second divided regions. Searching for one of the plurality of second divided areas where the jitter has been measured, and selecting one of the plurality of jitter measurement points included in the one of the searched plurality of second divided areas. An optical disc device that determines an optimal combination of the variable X and the variable Y corresponding to the first and second variables. 10. The minimum jitter value searching means may include four initial regions each having a rectangular shape equal to each other.
Dividing into the divided areas, based on the type of the information carrier determined by the information carrier determining means, the four first
Selecting one of the divided areas, the jitter minimum value searching means selects the four first
Dividing the one of the divided areas into four second divided areas having a square shape equal to each other;
The search according to claim 9, wherein one of the four second divided regions in which the minimum jitter is measured among the jitters measured at the four second jitter measurement points respectively located at the center of gravity of the divided region is searched. Optical disk device. 11. The optical disk device according to claim 9, wherein the variable X includes a cutoff frequency, and the variable Y includes a boost amount. 12. The optical disk device according to claim 9, wherein the variable X includes a high-frequency delay amount, and the variable Y includes a low-frequency delay amount. 13. A focus control means for controlling said convergence means so that said light beam is brought into a predetermined convergence state with respect to said record carrier, and such that said light beam scans a track on said record carrier correctly. The optical disc device according to claim 9, further comprising: a tracking control unit configured to control the convergence unit, wherein the variable X includes a tracking position, and the variable Y includes a focus position. 14. A radial tilt adjusting means for adjusting a tilt of the light beam in a radial direction with respect to the record carrier, and a tangential tilt adjusting means for adjusting a tilt of the light beam in a tangential direction with respect to the record carrier. The optical disk device according to claim 9, wherein the variable X includes a radial tilt, and the variable Y includes a tangential tilt. 15. An optical disk device for optically reproducing information recorded on an information carrier by a light beam emitted from a light source, comprising: a converging means for converging and irradiating the light beam; A light detection unit that generates a reproduction signal corresponding to the reflected light or the transmitted light of the beam; a waveform equalization unit that changes a frequency characteristic of the reproduction signal generated by the light detection unit; A jitter measuring means for measuring the jitter of the output signal; and a jitter measuring means for changing the jitter measured by the jitter measuring means in an initial area on an XY plane defined by two variables, a variable X and a variable Y. A jitter minimum value searching means for obtaining a minimum value; and a reproduction speed detecting means for detecting a reproduction speed of the reproduction signal; Dividing the initial region into a plurality of first divided regions having the same shape as each other, and selecting one of the plurality of first divided regions based on the reproduction speed detected by the reproduction speed detection means. The minimum jitter value searching means,
The one of the divided regions is divided into a plurality of second divided regions having the same shape as each other, and a minimum of jitter measured at a plurality of jitter measurement points respectively located at the center of gravity of the plurality of second divided regions. Searching for one of the plurality of second divided areas where the jitter has been measured, and selecting one of the plurality of jitter measurement points included in the one of the searched plurality of second divided areas. An optical disc device that determines an optimal combination of the variable X and the variable Y corresponding to the first and second variables. 16. The jitter minimum value searching means may be configured to set the initial area to four first areas having a rectangular shape equal to each other.
Dividing into divided areas, selecting one of the four first divided areas based on the reproduction speed detected by the reproduction speed detection means, Two first
Dividing the one of the divided areas into four second divided areas having a square shape equal to each other;
16. The optical disk device according to claim 15, wherein one of the four second divided regions in which the minimum jitter is measured among the jitters measured at the four jitter measurement points respectively located at the center of gravity of the divided region is searched. . 17. The optical disk device according to claim 15, wherein the variable X includes a cutoff frequency, and the variable Y includes a boost amount. 18. A reference signal generating means for generating a monotone signal, a binarization means for binarizing the monotone signal, and the binarization means for binarizing a center of a signal amplitude of the monotone signal. Data slice balance setting means for setting a value conversion circuit; clock generation means for generating a clock signal; the monotone signal binarized by the binarization means; and the clock signal generated by the clock signal generation means Phase comparison means for comparing the phase with the phase error signal, a charge pump circuit for averaging the phase error signal output from the phase comparison means, and the phase error output from the phase comparison means. Phase adjustment means for adjusting a phase shift of a signal; and jitter measurement means for measuring jitter based on the phase error signal output from the phase comparison means. Jitter minimum value searching means for obtaining a minimum value of the jitter in an initial area on an XY plane defined by two variables, a variable X and a variable Y, which can change the jitter measured by the jitter measuring means. The minimum jitter value searching means divides the initial area into a plurality of first divided areas having the same shape as each other, and a plurality of first divided areas respectively located at the centers of gravity of the plurality of first divided areas.
One of the plurality of first divided regions where the minimum jitter is measured among the jitters measured at the jitter measurement point is searched, and the minimum jitter value searching means searches the plurality of first divided regions.
The one of the divided regions is divided into a plurality of second divided regions having the same shape as each other, and jitters measured at a plurality of second jitter measurement points respectively located at the centers of gravity of the plurality of second divided regions are determined. One of the plurality of second divided regions in which the minimum jitter is measured is searched, and the plurality of second jitter measurement points included in the one of the searched plurality of second divided regions are searched. For determining an optimal combination of the variable X and the variable Y corresponding to one of the following:
circuit. 19. The P according to claim 18, wherein the variable X includes a cutoff frequency, and the variable Y includes a boost amount.
LL circuit. 20. The phase adjustment unit, wherein the current balance in an output stage included in the charge pump circuit is varied so as to adjust the phase shift of the phase error signal output from the phase comparison unit. Item 18. The PLL circuit according to Item 18.