JP2003016673A - Optical disk drive - Google Patents

Abstract

PROBLEM TO BE SOLVED: To properly perform groove tracking servo, while the quality of information signal components from an aperiodic structure is prevented from deteriorating below a required level, in a band where frequency is higher than in a groove tracking servo band. SOLUTION: The optical disk drive is provided with a controller which reads information from the aperiodic structure in the radial direction of an optical disk and which controls the offset displacement in a tracking direction of the objective lens of an optical pickup, for the purpose of preventing deterioration in the quality of information signal components from the aperiodic structure below a required level, in a band where frequency is higher than in a groove tracking servo band. With the aim of realizing the offset displacement, an electric current for an objective lens actuator is set smaller than the allowable upper limit current value of the objective lens actuator and at the current value (its absolute value > 0) enabling the tracking displacement of the objective lens.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk drive device.

[0002]

2. Description of the Related Art An optical disk drive device for recording and reproducing information by converging a light flux on an optical disk recording surface by an optical pickup device is a "CD drive or DVD drive".
It is widely known as etc.

There is a general optical disk such as a CD-ROM "for information reproduction in which information is recorded in advance", but a CD-R (compact disk recordable)
And DVD-R (Digital Video Disc Recordable), CD-RW (CD Rewritable), DVD-RW
There are some such as (DVD rewritable) that can record information.

The "optical disc capable of recording information" includes:
Wobbles and land pre-pits (LP) are used to indicate synchronization information (synchronization pattern) and address information on the optical disc.
P) and the like are formed.

In FIG. 1A, reference numeral 2 indicates a "groove track" and reference numeral 3 indicates a "land track". Figure 1
As shown in (b), the light beam (light beam) B is condensed as a light spot SP on the groove track 2 and guided on the groove track 2. In this way, the light spot S
The servo control that allows P to be guided on the groove track 2 is the “groove tracking servo”.

"Wobble" is "meandering of the edge of the groove track 2" as shown in FIG. 1 (a). Further, as shown in FIG. 1B, the land prepits 4 are formed in the land track portion. As shown in FIG. 1B, the light beam B is condensed on the recording surface (the surface on which the groove track 2, the land track 3 and the land prepit 4 are formed) via the transparent protective film 7.

As shown in FIGS. 1A and 1B, since wobbles and land prepits are formed on the recording surface of a recordable optical disk, the radial direction of the optical disk (groove track is The microscopic structure in the direction transverse to the track, referred to herein as the "radial direction", is the "aperiodic structure".

That is, the "virtual cross section in the radial direction" of an optical disc on which wobbles or land prepits are formed has an uneven cross-sectional shape due to grooves. Changes in the radial direction instead of being constant, the groove shape in the cross section becomes "aperiodic groove shape".

However, since the groove tracks 2 are periodically formed with the track pitch: PT shown in FIG. 1B, from this viewpoint, it can be said that the groove track 2 has a "periodic structure".

The "wobble signal" and "land pre-pit signal (hereinafter referred to as" LPP signal ")" are generated by the above "aperiodic structure" on the recording surface, and are "push-pull" for the groove tracking servo. The "signal" is generated by the "periodic structure". The wobble signal and the LPP signal generated by the aperiodic structure have a frequency band higher than that of the push-pull signal.

FIG. 2 shows a light receiving state of the light receiving means for obtaining a signal for groove tracking servo. The light receiving surface of the light receiving means 20 is divided by a dividing line 21 into two (for light receiving) regions 20A and 20B. The dividing line 21 corresponds to the groove direction (direction of the groove track 2 shown in FIG. 1) in the optical recording medium.

Reference numeral F is a light beam (detection light beam) obtained by separating a part of the "return light beam" reflected by the recording surface of the optical recording medium for the groove tracking servo. The portions indicated by reference numerals F1 and F2 are portions having a high light intensity generated by the interference of the reflected light from the groove track and the land track, and are called "track patterns".

When the light receiving signal generated in the area 20A is "A" and the light receiving signal generated in the area 20B is "B" and its differential signal: AB is generated, a signal as shown in FIG. 3A is obtained. can get.

The signal shown in FIG. 3A is a "push-pull signal" having a low frequency as shown in FIG.
It is a superposition of "high frequency signals" as shown in (c) and (d). The push-pull signal shown in FIG. 3B is a "signal for groove tracking servo".

In the groove tracking servo, the objective lens for focusing the light beam on the recording surface is "in the direction corresponding to the radial direction (the direction crossing the groove) of the optical disk" by the objective lens actuator based on the signal for the groove tracking servo. It is performed by displacing to. in this way,
The direction in which the objective lens is displaced for the groove tracking servo is called the "tracking direction". The displacement of the objective lens due to the groove tracking servo is called "tracking displacement".

The signal shown in FIG. 3C is a "wobble signal".
The signal is derived from the wobble of the groove track, and the signal shown in FIG. 3D is the "LPP signal", which is derived from the land prepit.

In FIG. 2, the center of the detected light flux F is the light receiving means 20.
The figure shows an "ideal case" located on the dividing line 21. When the center of the detected light flux F is displaced from the dividing line 21 in the “direction orthogonal to the dividing line 21 in the drawing (corresponding to the tracking direction)”, the C / of the wobble signal or the LPP signal is shifted.
N (carrier / noise) is significantly deteriorated. Detected light flux F
The deviation between the dividing line 21 and the dividing line 21 is caused by an assembling error of the optical system of the optical pickup device, "variation due to time or temperature change" in the positional relationship of the optical system, and the like.

The wobble signal shown in FIG. 4 (b) is an ideal case, and the amplitude is symmetrical with 0 level. On the other hand, a wobble signal in which the center of the detected light beam F is displaced in the tracking direction with respect to the dividing line 21 is, for example, as shown in
As shown in (a), it deviates from the 0 level. In this way, the “wobble signal deviated from 0 level” has a low C / N,
Unable to get proper synchronization information.

The deterioration of the wobble signal and the LPP signal is caused by the "deviation in the tracking direction" between the detected light beam F and the light receiving means 20.
Therefore, in order to correct the above deterioration, it is effective to displace the position of the objective lens in the tracking direction. Such displacement of the objective lens is called "offset displacement", and its magnitude is called "offset displacement amount".

If the amount of offset displacement is too large, "the coil of the objective lens actuator is destroyed by an excessive current passing through it" or "the resonance of the actuator increases and the tilt of the objective lens increases and the tilt of the optical disc is increased. The recording characteristics of the optical disc are disturbed "or" the amount of offset displacement exceeds the tracking operation range of the objective lens "," the optical spot shape on the recording surface of the optical disc deteriorates, and the recording characteristic of the optical disc is impaired. " Various troubles such as "occurrence".

[0021]

SUMMARY OF THE INVENTION The present invention eliminates the various problems described above, and prevents the quality of the information signal component from the aperiodic structure from deteriorating below a required level in a band having a frequency higher than the groove tracking servo band. The task is to

[0022]

According to a first aspect of the present invention, there is provided an optical disk drive apparatus, wherein "a light beam is focused on a recording surface of an optical disk having wobbles and / or land prepits to record / reproduce / erase information. Read the information from the aperiodic structure in the radial direction of the optical disc, and in order to prevent the quality of the information signal component from the aperiodic structure from deteriorating below the required level in the frequency band higher than the groove tracking servo band. It has a control means for controlling the amount of offset displacement that causes the objective lens of the pickup to be offset in the tracking direction. "It is characterized by the following points.

That is, the "current flowing through the objective lens actuator to realize the offset displacement amount" is smaller than the "allowable upper limit current value" of the objective lens actuator, and the current value (≠ 0 that allows the tracking displacement of the objective lens). ) ”. Note that all of these current values are absolute values.

The frequency of the current that gives the offset displacement to the objective lens of the optical pickup may be extremely low, and the current passing through the objective lens actuator in order to realize the amount of offset displacement is "DC-like (direct current or practically as low as DC. Frequency alternating current) ".

The maximum value of the current that can be passed through the objective lens actuator (the above-mentioned "allowable upper limit current value of the objective lens actuator") is generally about 0.3 A in absolute value, and a current larger than this value is passed through. If it is damaged, the “heat-bonded coil” of the objective lens actuator may be broken and broken or deformed.

In order to realize the offset displacement amount,
When a current of the allowable upper limit current value is passed to the objective lens actuator, if a current for groove tracking servo is passed, an excessive current may flow to the coil of the objective lens actuator and destroy the coil. Tracking servo cannot be performed.

Therefore, in the optical disc drive apparatus according to the first aspect, as described above, the current flowing through the objective lens actuator to realize the offset displacement amount is smaller than the allowable upper limit current value of the objective lens actuator and It is set to a current value (≠ 0) that enables tracking displacement. " For example, if the allowable upper limit current value is 0.3 A, offset displacement is realized by 0.2 A of the allowable upper limit current value, and groove tracking servo is performed by the remaining 0.1 A.

The "current flowing through the objective lens actuator in order to realize the offset displacement amount" in the optical disk drive apparatus according to claim 1 is such that the tilt of the objective lens due to the resonance of the objective lens actuator is equal to or less than the allowable upper limit value. It can be defined (Claim 2).

The "current flowing through the objective lens actuator to realize the offset displacement amount" in the optical disk drive device according to claim 1 is also "from the size of the movable range in the tracking direction of the objective lens by the objective lens actuator, The amount of the average maximum eccentricity of the optical disk is excluded from the current value that is realized as the offset displacement amount (claim 3), and "the deterioration of the wavefront aberration due to the offset displacement of the objective lens is the maximum allowable range of the deterioration of the wavefront aberration." It is also possible to set the current value within the range (claim 4).

An optical disk drive device according to a fifth aspect of the present invention is "recording / reproducing / writing information by converging a light beam on a recording surface of an optical disk having wobbles and / or land prepits.
The information from the aperiodic structure in the radial direction of the optical disc is read by performing one or more erasures, and the quality of the information signal component from the aperiodic structure is degraded to a required level or less in a frequency band higher than the groove tracking servo band. So as not to,
It has a control means for controlling an offset displacement amount for offset displacement of the objective lens of the optical pickup in the tracking direction ", and is characterized by the following points.

That is, "the offset displacement amount of the objective lens is optimized" according to the type of the optical disc. For example, usable optical disks are CD-R, CD-RW, DVD +
R, DVD + RW, DVD-RAM, DVD-R, DV
It is possible to use two or more types of D-RW and the like, and to optimize the offset displacement amount of the objective lens corresponding to them.

The optical disk drive device according to the fifth or sixth aspect of the present invention can be configured to use an optical disk having an aperiodic structure and reproduce information on an optical disk having no aperiodic structure. In this case, since an "information signal component from an aperiodic structure" such as a wobble signal or an LPP signal is not generated from an optical disc having no aperiodic structure, "an optical disc having no aperiodic structure is used (information reproduction When “)”, the offset displacement amount of the objective lens of the optical pickup can be set to 0 (claim 7). When the offset displacement amount is 0, the objective lens is subjected to the groove tracking servo with reference to the "neutral point", that is, "the position when no current is passed through the objective lens actuator".

For example, the optical disk is a CD-DA, CD-
The offset displacement amount of the objective lens of the optical pickup can be set to 0 when the ROM or the DVD-ROM is used (claim 8).

The optical pickup of the optical disk drive apparatus according to any one of claims 5 to 8 can have "two or more semiconductor lasers having mutually different emission wavelengths". In such a case, the offset displacement amount of the objective lens is “optimized according to each semiconductor laser” (claim 9).
be able to.

In the optical disk drive device according to the ninth aspect, it is possible to "make the detecting section for detecting the return light beam from the optical disk common to the light beams emitted by the respective semiconductor lasers" (claim 10). It is also possible to have two or more detectors for detecting the return light flux from the optical disk (claim 11).

According to a twelfth aspect of the present invention, there is provided an optical disc drive apparatus in which "a light beam is condensed on a recording surface of an optical disc having wobbles and / or land prepits to perform one or more of information recording / reproducing / erasing, and a radial direction of the optical disc. The information from the non-periodic structure is read, and the objective lens of the optical pickup is tracked so that the quality of the information signal component from the non-periodic structure does not deteriorate below the required level in the frequency band higher than the groove tracking servo band. And a control means for controlling the amount of offset displacement for offset displacement in the direction. "And is characterized by the following points.

That is, the "control means" has a control section and a limiter.

The "control section" generates a control signal for controlling the objective lens actuator so that the quality of the information signal component from the aperiodic structure is optimized. "limiter"
Limits the maximum value of the control signal output from the control unit in accordance with a predetermined limiter value.

In the optical disk drive device according to the twelfth aspect of the present invention, the predetermined limit value limited by the limiter is defined as "the current value of the current flowing to the objective lens actuator in order to realize the offset displacement amount, and the allowable upper limit current value of the objective lens actuator. It can be set as a value which is smaller and is realized as a current value (≠ 0) which enables tracking displacement of the objective lens (claim 13).

The optical disk drive device according to the twelfth or thirteenth aspect can be configured so as to "suitable for a plurality of types of optical pickups", and in that case, "limit value according to the objective lens actuator of the used optical pickup". It is possible to have a limit value generating means for generating (Claim 14). In this case, the control unit can cause the limit value generating means to generate the limit value in accordance with the "actuator identification signal from the optical pickup" (claim 15).

In the optical disk drive apparatus according to any one of claims 12 to 15, "the quality of the information signal component from the aperiodic structure is not deteriorated to a required level or less by the offset displacement of the objective lens due to the limiter value. The control unit can be configured to output a signal to that effect (claim 16).

Similarly, any one of claims 12 to 15 can be used.
In the optical disc drive apparatus described in the above paragraph, the control unit can be configured to output "a signal indicating the degree of quality of the information signal component from the aperiodic structure due to the offset displacement of the objective lens due to the limit value" (claim 17). ).

An optical disk drive device according to a eighteenth aspect of the present invention states that "a light beam is condensed on a recording surface of a DVD or CD optical disk to reproduce at least information, and information from an aperiodic structure in the radial direction of the optical disk is read. In order to prevent the quality of the information signal component from the aperiodic structure from deteriorating below the required level in the frequency band higher than the reading and groove tracking servo band, the offset displacement amount that offsets the objective lens of the optical pickup in the tracking direction is set. It has a control means for controlling it "and is characterized by the following points.

That is, for a DVD type optical disk having an aperiodic structure, the objective lens is offset-displaced according to the control of the control means, and D having no aperiodic structure is used.
For a VD type optical disc and a CD type optical disc, the offset displacement amount of the objective lens is set to zero.

In the optical disk drive device according to the eighteenth aspect, it is possible to "use a hologram laser for the CD optical system" (the nineteenth aspect), and in that case, the position of the hologram laser is "adjusted when the optical pickup is assembled. By this, it is possible to provide an optical disk drive device in which the offset of the push-pull signal is removed (claim 20).

In the optical disk drive device according to the above-mentioned claim 19 or 20, tracking is performed on an optical disk having no aperiodic structure by "adjusting the reference position where the offset displacement amount in the objective lens is 0 when the optical pickup is assembled". Can be properly performed (claim 21).

[0047]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 5 conceptually shows an embodiment of an optical information recording apparatus of the present invention. The divergent light beam emitted from the semiconductor laser 41 as a light source is made into a substantially parallel light beam by the collimator lens 42, passes through the beam splitter 43, is deflected by 90 degrees in the optical path by the deflection prism 44, and is incident on the objective lens 45. It is condensed as a minute light spot on the recording surface through the transparent substrate.

Information is recorded on the optical disc MD by this light spot. In this embodiment, "reproduction of information and deletion of information" are also performed on the optical disc MD.

The light beam reflected by the recording surface of the optical disk MD becomes a "return light beam", is returned to a substantially parallel light beam by the objective lens 45, and is deflected by the deflection prism 44.
The light is reflected by the beam splitter 43, and is converged by the detection lens 46 to enter the light receiving means 47. Various servo signals and information signals (when information is reproduced) are generated from the light reception signal generated by the light receiving means 47.

Of the light receiving means 47, the "portion for detecting the signal for groove tracking servo" is the light receiving means 20 (hereinafter referred to as "tracking light receiving means") described with reference to FIG.
Also, the light receiving surface is divided into two regions in a direction corresponding to the tracking direction by a dividing line corresponding to the groove direction.

The light receiving signal generated by the light receiving means 47 is inputted to the control means 48, and the control means 48 generates the above information signal and sends it to the information reproducing section. At the same time, various servo signals are generated from the light receiving signal. To do. Among the generated servo signals, the groove tracking servo signal (track error signal: push-pull signal) and the focusing servo signal (focus error signal) are input to the actuator 49, which is an “objective lens actuator”.

The actuator 49 displaces the objective lens 45 in the optical axis direction in response to the focusing servo signal, and moves the objective lens 45 in the tracking direction (tracking light receiving means 20) orthogonal to the optical axis in response to the groove tracking servo signal. In a direction orthogonal to the dividing line 21).

FIG. 6 shows a typical example of the objective lens actuator. In the actuator 49, the objective lens 61 is fixedly held by the holding member 62, and the holding member 6
Reference numeral 2 is engaged with a fixed member 66 provided on a yoke 68 (which forms a magnetic path by the magnet 67) also serving as a base by a wire spring 65 "movable in the tracking direction TR and the focusing direction FC".

The focusing servo displaces the objective lens 61 in the focusing direction (optical axis direction of the objective lens 61) integrally with the holding member 62 by passing a current according to the focus error signal through the focusing servo coil 63. It is done by

The groove tracking servo is performed by displacing the objective lens 61 in the tracking direction TR integrally with the holding member 62 by passing a current according to the push-pull signal through the groove tracking servo coil 64.

The "differential signal of the light receiving signal generated in the regions on both sides of the dividing line" of the tracking light receiving means is wobbled as the "information signal component due to the aperiodic structure in the radial direction of the optical disc" as described above. Signal and LP
If the circuit including the P signal and generating a differential signal has a sufficiently high band, as shown in FIG. 3A, a push-pull signal due to groove crossing and a “signal change due to groove shape change due to wobble or LPP” occur. The superimposed signal is detected.

FIG. 7 conceptually shows only one characteristic part of the first embodiment of the optical disk drive device according to the first aspect. Reference numeral 47A indicates "a portion of the light receiving means 47 for detecting a signal for groove tracking servo".
That is, it is a “light receiving means for tracking”. The received light signal generated by the tracking light receiving means 47A is subjected to a difference operation by a differential amplifier 480 having a sufficiently high band, and the obtained "differential signal (above-mentioned AB)" is divided into two and one is a low-pass filter. 481 and the other input to the high pass filter 482.

The high-pass filter 482 removes the low frequency component from the input signal and generates the "wobble signal" shown in FIG. 3 (c) and the "LPP signal" shown in FIG. 3 (d). The wobble signal and the LPP signal are input to the offset current generator 484.

The offset current generator 484 detects the amplitude of the wobble signal and / or the LPP signal, and determines the "original offset current" that maximizes this amplitude as a predetermined "relationship between the amplitude and the original offset current." Formula or table that determines The original offset current (absolute value) thus determined is Iw (max).

On the other hand, the "allowable upper limit current value (absolute value)" which is the maximum value of the current that can be passed through the "coil for groove tracking servo" of the objective lens actuator 49 is set to Im.
Let it be ax. In addition, “current (absolute value) capable of performing good groove tracking servo” is defined as It, and “minimum current (absolute value) necessary for performing proper groove servo tracking servo”, that is, groove servo tracking servo The minimum current required for the trouble-free operation is Itmin.

Furthermore, the wobble signal and / or the LP
Let Iwmin be the offset current when the C / N as the quality of the P signal is the minimum necessary (the correspondence with the signal is known in advance in the form of a mathematical expression or a table).

The offset current generator 484
Thus, the "offset current" is generated. In addition,
Current causes offset displacement of the objective lens
Is the current applied to the objective lens actuator 49.
And let this be Ioff. I₁= Imax-It, I
_Two= Imax-Itmin, current: I₁, I _TwoTo
Define. I₁> I_TwoIs.

As shown in FIG. 8, the original offset current: I
Comparing w (max) and current: I ₁ , Iw (max) ≦
When I ₁ , offset current: Ioff = Iw
(Max), the offset current is passed through the actuator 49 to offset-displace the objective lens in the tracking direction.

Offset displacement is offset current: Iw
It is determined by (max). In this case, the amplitude of the wobble signal and / or the LPP signal can be maximized, the C / N of these signals can be maximized, and good groove tracking servo can be executed.

That is, the tracking current generator 483
In response to a signal (track error signal: push-pull signal) from the low-pass filter 481, a current for groove tracking servo is generated and applied to the actuator 49 within the range of the maximum tracking current: It, and the groove tracking servo is “offset”. At the displaced objective lens position ".

When Iw (max)> I ₁ , Iw
When min and I ₁ are compared and Iwmin ≦ I ₁ , the objective lens is offset-displaced with an offset current: Ioff = I ₁ . In this case, it is possible to perform good groove tracking servo while securing the C / N for the wobble signal and / or the LPP signal at “more than the necessary minimum”.

In this case also, the tracking current generator 48
The actuator 3 generates a current for groove tracking servo within the range of the maximum tracking current: It according to the push-pull signal from the low pass filter 481.
And the groove tracking servo is performed at the “offset displaced objective lens position”.

When Iwmin> I ₁ , Iwmin and I ₂ are compared. If Iwmin ≦ I ₂ , the offset current is set to Ioff = Iwmin, and the objective lens is offset-displaced. In this case, it is possible to perform "appropriate groove tracking servo" while securing C / N for the wobble signal and / or the LPP signal to "more than the necessary minimum".

In this case, the tracking current generator 483
Responds to the push-pull signal from the low-pass filter 481 to generate a current for groove tracking servo within the range of the maximum tracking current: Imax-Iwmin and apply it to the actuator 49 to cause the groove tracking servo to be “offset displaced objective lens”. Position ”.

When Iwmin> I ₂ , "offset is impossible". That is, in this state, it is not possible to ensure both the required minimum C / N of the wobble signal and / or the LPP signal and the proper groove tracking servo. Therefore, in this case, "readjust the neutral point of the objective lens" or "replace the optical pickup body".

The differential amplifier 480, low-pass filter 481, high-pass filter 482, tracking current generator 483, and offset current generator 484 shown in FIG.
It constitutes a "section for controlling offset displacement" in the control means 48 shown in FIG. It should be noted that instead of using the “amplitude itself” of the wobble signal and / or the LPP signal as the “amplitude of the information signal component due to the aperiodic structure of the optical disc”, the tracking light receiving means 47A can be used from both sides of the dividing line. "Sum of received light signals (adding circuit with relatively low bandwidth, sum signal with low frequency components extracted,
It is also possible to use the ratio of "the sum signal obtained by extracting the high frequency component by the high-pass filter)" and "the amplitude itself". Thus, the "wobble signal and / or LP
If the ratio of the P signal and the sum signal is used, it is possible to reduce the influence of the DC change in the light amount of the return light flux.

When an "offset" occurs in the push-pull signal described above, this offset is "a positional shift between the detection beam and the dividing line in the tracking light receiving means".
The offset and the positional shift have a 1: 1 relationship. In the ideal state, as shown in FIG. 2, the detection beam F is completely divided into two by the dividing line 21, and the offset becomes zero. This matches the condition when “the quality of the wobble signal or the LPP signal is the best”.

Therefore, it is also possible to detect the push-pull offset amount which is the "offset amount of the push-pull signal" and set the offset current value at which it becomes zero to the above: Iw (max).

Various methods can be considered as a method of detecting the offset of the push-pull signal. For example, in the innermost peripheral portion and the outermost collecting portion of the optical disc, there is no groove on the recording surface, and the recording surface is a "mirror portion" in these portions. Therefore, when the return light flux from this portion is incident on the tracking light-receiving means 47A, the differential signals of the light-receiving signals generated on both sides of the dividing line at that time have only the DC component corresponding to the offset. The offset amount of the push-pull signal can be detected from the output of the dynamic amplifier 480.

Further, as is well known, in an optical pickup device which employs the differential push-pull tracking method, a plurality of optical spots are arranged so that the main spot and the sub spot are located at positions shifted by 1/2 pitch of the groove. A spot is formed on the recording surface, and a light receiving unit having a dividing line in the groove corresponding direction is provided corresponding to each of the returning light fluxes by the individual light spots. Therefore, the main and sub push-pull signals are out of phase by π.

By combining the gains of the main and sub signals and taking the differential between the main and "sub sum", the DC component is removed, and a differential push-pull signal in which the amplitude component is doubled is obtained. To be At this time, when the sum of the main and the sub is taken, the amplitude component is removed, and a signal in which the DC component is doubled is obtained. By this "signal in which the DC component is doubled",
The offset amount can be detected with high sensitivity.

FIG. 9A shows a typical example of the "relationship between the offset displacement amount and the tilt amount due to the resonance of the objective lens actuator" when the objective lens is offset displaced in the tracking direction. If the tilt amount becomes large, the recording characteristics on the optical disc may be hindered. In such a case, for example, the C / N of the wobble signal and / or the LPP signal is set to the minimum necessary amount as the current that gives the offset displacement. Offset current: I
The offset displacement is performed with a current larger than wmin and smaller than the allowable upper limit of the tilt amount.

In the example of FIG. 9A, if the upper limit value of the tilt amount allowed for the objective lens is 15 minutes, the offset displacement amount of the objective lens is 0.1 mm or less. Further, the offset displacement may be realized by using “current: current larger than Iwmin” as the offset current.

In the "objective lens actuator" of FIG. 6 explained above, the focusing servo coil 63 is used.
The moving range of the objective lens is limited by the gap between the yoke 68 and the yoke 68. For example, the range of movement of the objective lens is ± 0.4 mm
Then, if the eccentricity of the optical disk is ± 0.2 mm at maximum,
It is preferable to set the offset current so that the offset displacement amount of the objective lens is 0.2 mm or less and offset the objective lens position in the tracking direction.

FIG. 9B shows an example of the "relationship between the offset displacement amount and the wavefront aberration of the objective lens" when the objective lens is offset displaced in the tracking direction. When the wavefront aberration of the objective lens becomes large, the shape of the light spot formed on the recording surface of the optical disc deteriorates, and the recording characteristics on the optical disc are impaired.

In the case of FIG. 9B, the maximum allowable range of the wavefront aberration deterioration of the objective lens is, for example, 0.04λr.
If it is ms (4% or less of wavelength at root mean square), the offset displacement of the objective lens is 0.2 mm.
The off-state current may be set so as to be as follows.

Of course, the offset current value to be set is "wobbled" in both "when the offset current value is set according to the eccentricity of the optical disk" and "when the offset current value is set in relation to deterioration of wavefront aberration". It is premised that the offset current when the C / N of the signal and / or the LPP signal becomes the necessary minimum: a current larger than Iwmin.

The optical disk drive device described in the above embodiment condenses a light beam on the recording surface of the optical disk MD having wobbles and / or land prepits to perform one or more of information recording / reproducing / erasing, Information is read from the aperiodic structure in the radial direction of the optical disc, and the optical pick-up of the optical pickup is set so that the quality of the information signal component from the aperiodic structure does not deteriorate below the required level in the frequency band higher than the groove tracking servo band. A control unit that controls an offset displacement amount that offset-displaces the objective lens in the tracking direction is provided, and a current passing through the objective lens actuator 49 to realize the offset displacement amount is smaller than an allowable upper limit current value Imax of the objective lens actuator, and , Current value that enables tracking displacement of the objective lens (≠ 0) It is defined ones (claim 1).

As described with reference to FIG. 9A, the tilt of the objective lens due to the resonance of the objective lens actuator allows the current (offset current) passing through the objective lens actuator to realize the offset displacement amount. It is also possible to set it so that it is less than or equal to the upper limit (Claim 2).
It is also possible to set to "a current value that is realized as an offset displacement amount by subtracting the average maximum eccentricity amount of the optical disk from the size of the movable range of the objective lens in the tracking direction by the objective lens actuator" (claim 3). The deterioration of the wavefront aberration due to the offset displacement of the objective lens can be set to a current value within the maximum allowable range of the deterioration of the wavefront aberration (claim 4).

In the embodiment shown in FIG. 5, the optical disc MD is a CD-R, a CD-RW, a CD-DA, a CD.
-When "CD type optical disk" such as ROM can be used, the appropriate offset displacement amounts are CD-R and CD-
Since it differs from the RW, in this case, an appropriate offset displacement amount can be set according to each,
Since the CD-DA and the CD-ROM do not have wobbles or LPPs, in such a case, the offset current is set to 0 so that the offset displacement amount becomes 0. However, even when the wobble or LPP is not included, the above-mentioned “push-pull signal offset” may occur. In such a case, even if an offset displacement is given to “set the push-pull signal offset to 0”. Good.

Further, the optical disk MD in the embodiment of FIG. 5 is a DVD + R, a DVD + RW, a DVD-RA.
D for M, DVD-R, DVD-RW, DVD-ROM, etc.
In the case of a VD type optical disc, an appropriate offset displacement amount is DVD + R, DVD + RW, DVD-RAM, D
Since VD-R and DVD-RW are different, in this case,
Make it possible to set an appropriate offset displacement amount for each.

Since the DVD-ROM does not have wobble or LPP, in such a case, the offset current is set to 0 in order to set the offset displacement amount to 0. Of course, even when the DVD type optical disk does not have wobble or LPP, the offset displacement may be given so as to “set the push-pull signal offset to 0”.

As described above, in order to realize an appropriate offset displacement amount according to the type of optical disc, the above-mentioned current values: Iw (max) and Iwmin depending on the type of optical disc.
, While detecting the type of optical disk,
Current value according to the detection result: Iw (max) or Iwm
The offset current generation unit 484 may generate the offset current using in.

Since the optical disk drive device of FIG. 5 has a single light source, it is not possible to use a CD type optical disk and a DVD type optical disk, but a semiconductor laser having an emission wavelength (790 nm) for the CD type optical disk is used. , The emission wavelength (660n
If a semiconductor laser having the above m) is incorporated into the same optical pickup and these semiconductor lasers are switched and used, a CD optical disk and a DVD optical disk are used for the same optical disk drive device. It becomes possible to do.

FIG. 10 shows two semiconductor lasers 41A and 4A.
An example of an optical pickup using 1B will be shown. Semiconductor laser 41A (wavelength for DVD optical disc: 660 nm)
The divergent light beam emitted from the collimator lens 42A is made into a substantially parallel light beam, and the first beam splitter 43A and the second beam splitter 43A
The beam splitter 43B is sequentially transmitted, the optical path is deflected by 90 degrees by the deflection prism 44, the objective lens 45 transmits the transparent substrate of the optical disc MD (DVD system), and it is condensed as a light spot on the recording surface.

The divergent light beam emitted from the semiconductor laser 41B (wavelength for CD type optical disk: 790 nm) is made into a substantially parallel light beam by the collimator lens 42B, reflected by the first beam splitter 43A, and then the second beam splitter 4 is emitted.
After passing through 3B, the deflection prism 44 deflects the optical path by 90 degrees, and the objective lens 45 transmits the transparent substrate of the optical disc MD (CD type optical disc) to condense it as a light spot on the recording surface.

With respect to the optical disk MD by the light spot,
Information is reproduced, recorded, or erased.

The light beam reflected by the recording surface of the optical disk MD becomes a "return light beam", is again made into a substantially parallel light beam by the objective lens 45, is deflected by the deflection prism 44, is reflected by the second beam splitter 43B, and is detected by the detection lens 46. Then, it is made into a focused light beam and is incident on the light receiving means 47 to generate an information signal and a servo signal.

In this way, the CD type optical disc and the DVD
When a separate semiconductor laser is used for the optical disc of the system, the “returning light flux incident on the light receiving means 47” is different for each semiconductor laser, and the offset displacement amount also differs for each semiconductor laser.

The appropriate offset displacement amount also differs depending on the type of the optical disc MD. Therefore, in this case, "D
Depending on whether a VD type optical disc is used or a CD type optical disc is used ", the individual type of optical disc (DVD + R, DV for DVD type)
D + RW, DVD-RAM, DVD-R, DVD-RW
For a CD system such as "CD-R, CD-RW, etc.", an "appropriate offset displacement amount" is determined and implemented in the same manner as described above.

The optical disc used is a CD-D.
When there is no wobble or land prepit like A, CD-ROM, DVD-ROM, etc., the offset displacement amount of the objective lens is set to zero.

FIG. 11 shows an optical pickup which uses two semiconductor lasers 41A and 41B having different emission wavelengths and two light receiving means corresponding to each of them. A divergent light beam emitted from the semiconductor laser 41A (wavelength for DVD optical disk: 660 nm) is made into a substantially parallel light beam by the collimator lens 42A, sequentially transmitted through the first beam splitter 43A and the second beam splitter 43B, and the deflection prism 44. Then, the optical path is deflected by 90 degrees, and the objective lens 45 transmits it through the transparent substrate of the optical disc MD (DVD system) and focuses it as a light spot on the recording surface. Information is reproduced, recorded, or erased by this light spot.

The light beam reflected on the recording surface of the disk becomes a "return light beam", is made into a substantially parallel light beam again by the objective lens 45, is deflected by the deflecting prism 44, and is sequentially passed through the second beam splitter 43B and the first beam splitter 43A. The light is transmitted through the detection lens 46 </ b> A to form a focused light beam, and the light receiving means 47
It is incident on A and generates an information signal and a servo signal.

The divergent light beam emitted from the semiconductor laser 41B is made into a substantially parallel light beam by the collimator lens 42B,
Of the beam splitter 43C, is reflected by the second beam splitter 43B, and the deflection prism 44 changes the optical path to 9
The optical disc MD is deflected by 0 degree and is moved by the objective lens 45.
It passes through a (CD) transparent substrate and is focused as a light spot on the recording surface. Information reproduction by this light spot,
Recording or erasing is performed.

The light beam reflected by the recording surface of the disk MD becomes a return light beam, is made into a substantially parallel light beam again by the objective lens 45, is deflected by the deflection prism 44, and is sequentially passed by the second beam splitter 43B and the third beam splitter 43C. The reflected light is focused by the detection lens 46B and enters the light receiving means 47B to generate an information signal and a servo signal.

As in this case, if "separate light receiving means (detection section for detecting return light beam)" is used for the CD type optical disk and the DVD type optical disk, "offset displacement of the objective lens is detected for each light receiving means. There is a need to change the amount. " Therefore, in this case, it depends on which light receiving means is used, and the individual type of the optical disc (DVD + R, DVD + RW, DVD-RA for the DVD system).
C for CD systems such as M, DVD-R, DVD-RW, etc.
D-R, CD-RW, etc.), the "appropriate offset displacement amount" is determined and implemented in the same manner as in the above case.

The optical disc used is a CD-D.
When there is no wobble or land prepit like A, CD-ROM, DVD-ROM, etc., the offset displacement amount of the objective lens is set to zero.

That is, the optical disk drive device having the optical pickup shown in FIGS. 10 and 11 collects a light beam on the recording surface of an optical disk having wobbles and / or land prepits to record / reproduce / erase information. 1) or more to read information from the aperiodic structure in the radial direction of the optical disc so that the quality of the information signal component from the aperiodic structure does not deteriorate below the required level in a band having a frequency higher than the groove tracking servo band. And a control means for controlling an offset displacement amount for offset displacement of the objective lens of the optical pickup in the tracking direction and optimizing the offset displacement amount of the objective lens according to the type of the optical disc (claim 5). is there.

The usable optical disk is CD-
R, CD-RW, DVD + R, DVD + RW, DVD-
Two or more kinds of RAM, DVD-R, DVD-RW, etc. are used to optimize the offset displacement amount of the objective lens corresponding to these (claim 6), and a non-periodic structure in the radial direction is formed. It is possible to reproduce information even on an optical disc that does not have the optical disc, and when an optical disc that does not have an aperiodic structure is used, the offset displacement amount of the objective lens of the optical pickup is set to 0 (claim 7). Specifically, the optical disc is a CD-DA or CD-RO.
In any one of M, DVD-ROM, etc., the offset displacement amount of the objective lens of the optical pickup is set to 0 (claim 8).

The optical pickup has two or more semiconductor lasers 41A and 41B whose emission wavelengths are different from each other.
The offset displacement amount of the objective lens is optimized according to each semiconductor laser (claim 9).

Further, in the optical disk drive device having the optical pickup shown in FIG. 10, the detection unit 47 for detecting the return light beam from the optical disk is made common to the light beams emitted by the respective semiconductor lasers (claim 10). In the optical disc drive device having the 11 optical pickups, two or more detection units 47A for detecting the return light flux from the optical disc,
47B (claim 11).

The offset displacement in the tracking direction is given to the position of the objective lens by "flowing an offset current through the objective lens actuator", but as described above, it is possible to communicate with the objective lens actuator including the groove tracking servo operation. The current value that can be used is limited.

The rotation speed of the optical disk is the highest at the time of reproducing the information among the recording, reproducing and erasing of the information on the optical disk. In order to make the groove tracking servo operation follow the optical disk rotated at such a high speed, it is necessary to increase the current flowing through the objective lens actuator as the rotational speed of the optical disk becomes higher. In other words, “the larger the offset displacement given to the objective lens is, the more the rotational speed of the optical disc is limited”.

Therefore, for the "recording medium having no aperiodic structure in the groove crossing direction" such as the optical disk drive apparatus according to the seventh or eighth aspect, the offset displacement amount of the objective lens is set to 0, Good information can be reproduced while ensuring good groove tracking servo.

FIG. 12 is a block diagram showing one embodiment of the optical disk drive device according to the twelfth aspect.

That is, this optical disk drive device collects a light beam on the recording surface of an optical disk having wobbles and / or land prepits to perform one or more of information recording / reproducing / erasing, and to perform non-radial recording on the optical disk. The information from the periodic structure is read, and the objective lens of the optical pickup 201 is moved in the tracking direction so that the quality of the information signal component from the non-periodic structure does not deteriorate below a required level in a band having a frequency higher than the groove tracking servo band. Control means for controlling an offset displacement amount for offset displacement, the control means generating a control signal for controlling the objective lens actuator so that the quality of the information signal component from the aperiodic structure is the best. The maximum value of the control signal output from the unit 205 and the control unit 205 is set to a predetermined limiter value. And a limiter 206 to limit me.

The optical pickup 201 shown in FIG. 12 has the structure as shown in FIG. 5, FIG. 10 or FIG. Reference numeral 202 is a light receiving element as "light receiving means", reference numeral 203
Shows an "objective lens actuator" as shown in FIG.

The decision signal generator 204 outputs a signal having a correlation with the quality of the information signal component from the aperiodic structure, that is, the wobble signal or the LPP signal (for example, wobble amplitude signal,
LPP amplitude signal, push-pull offset signal, differential push-pull type main push-pull and sub-push-pull sum signal, etc.) are generated.

The control unit 205 controls the objective lens actuator 203 so that "the quality of the wobble signal or the LPP signal is the best (for example, the C / N is the maximum)" according to the signal output from the determination signal generation unit 204. A control signal (a signal corresponding to the above-mentioned current value: Iw (max)) is output.

If the "signal output from the determination signal generator 204" is wobble amplitude or LPP amplitude, the controller 2
Reference numeral 05 is a “lens shift signal (the above-mentioned original offset signal)” such that a DC current (current value: Iw (max)) that maximizes the output signal of the determination signal generation unit 204 flows to the objective lens actuator 203. Is output.

When the signal output from the judgment signal generator 204 is a push-pull offset signal or an offset signal of the sum signal of the main push-pull and the sub-push-pull of the differential push-pull method, the controller 205 determines the judgment signal. It outputs a “lens shift signal (the above-mentioned original offset signal)” such that a DC current (current value: Iw (max)) such that the output signal of the generation unit 204 becomes zero flows into the objective lens actuator 203.

This “lens shift signal” is applied to the limiter 20.
Enter in 6. As a “predetermined limit value” for the limiter 206, the current value of the current flowing to the objective lens actuator to realize the offset displacement amount is smaller than the allowable upper limit current value of the objective lens actuator, and
A value that is realized as a current value (absolute value of current value> 0, value corresponding to the above current values: I ₁ and I ₂ ) that allows tracking displacement of the objective lens is set (claim 1
3).

The limiter 206 compares the lens shift signal input from the control unit 205 with the limit value, and when the absolute value of the lens shift signal is smaller than the limit value, the "lens shift signal input from the control unit 205". Is output as is. On the contrary, when the absolute value of the lens shift signal is equal to or larger than the limit value, the “limit value” is output. The signal output from the limiter 206 is combined with the groove tracking servo signal in the combining unit 207 and applied to the objective lens actuator 203 of the optical pickup 201.

Therefore, while ensuring a good or proper groove tracking servo, the deterioration of the quality of the information signal component due to the aperiodic structure is effectively reduced, and the proper optical disc which does not damage the objective lens actuator is obtained. You can drive.

Since the movable range and the allowable current of the objective lens actuator are determined by the configuration of the objective lens actuator, if the limit value can be set for each different type of objective lens actuator, a plurality of types of objective lens actuators can be used. Can handle.

FIG. 13 is a block diagram showing an embodiment of an optical disk drive device according to claims 14 and 15. In addition to the structure of the optical disk drive device shown in FIG. 12, it has a limit value generation unit 209 as "limit value generation means", and can be adapted to a plurality of types of optical pickups, and can be used as an objective lens actuator of the used optical pickups. A limit value corresponding to the limit value is generated (claim 14).

The control unit 205 causes the limit value generation unit 209 to generate a limit value in accordance with the "actuator identification signal" from the optical pickup 201, and the generated limit value causes the "limiter 206 to determine the absolute value of the lens shift signal. "Limit the upper limit."

As described above, the movable range and allowable current of the objective lens actuator are determined by the configuration of the objective lens actuator, and the limit value when offsetting the objective lens differs depending on the type of the objective lens actuator.

Therefore, as shown in FIG. 13, the limiter 2
The limit value of 06 is input from the outside (limit value generation unit 209), the optical pickup 201 outputs the "actuator identification signal for identifying the type of the objective lens actuator", and the actuator identification signal is output by the control unit 205. Then, the control unit 205 changes the “limit value output by the limit value generation unit 209” according to the actuator identification signal, so that a plurality of types of actuators can be supported.

The limit value generated by the limit value generating means is "a value that does not damage the objective lens actuator and can perform groove tracking servo properly or satisfactorily", and the above-mentioned current as an offset current value. Value: A value that can realize I ₁ or I ₂ , Iwmin, and the like.

As in the example described above, Iwmin> I
When the value is ₂ , “offset is impossible”, and in this state, it is impossible to secure the necessary minimum C / N of the wobble signal and / or the LPP signal and the proper groove tracking servo. In such a case, it is preferable to be able to display "to that effect (it is impossible to achieve both the required minimum C / N of the wobble signal and / or the LPP signal and the proper groove tracking servo)".

FIG. 14 is a block diagram showing an embodiment of an optical disk drive device according to claims 16 and 17. In addition to the configuration shown in FIG. 12, the control unit 205 controls the quality (C / C of the information signal component from the aperiodic structure depending on the offset displacement of the objective lens due to the limiter value.
N) can be prevented from deteriorating below the required level, a signal to that effect can be output to the external I / F section (communication means by serial communication, host I / F means, etc.) 210. (Claim 16).

In this way, it is possible to easily detect the adjustment abnormality of the pickup in the adjustment process and the inspection process, for example.

Further, the control unit 205 may output a "signal indicating the quality level of the information signal component from the aperiodic structure due to the offset displacement of the objective lens by the limit value" (claim 17). By doing this, even if the limit value is not adjusted to the highest state, "a wobble signal or LPP signal of a certain level or higher"
If it can detect, it is possible to easily make a judgment such as passing the adjustment or inspection.

FIG. 15 shows an example of an optical pickup used in the optical disk drive device according to the nineteenth aspect. This optical disk drive device is a "DVD system or CD
System collects the light flux on the recording surface of the optical disc, at least reproduces the information, reads the information from the aperiodic structure in the radial direction of the optical disc, and aperiodically in the frequency band higher than the groove tracking servo band. In order to prevent the quality of the information signal component from the structure from deteriorating below the required level, the DVD system having an aperiodic structure has a control means for controlling an offset displacement amount for offset displacement of the objective lens of the optical pickup in the tracking direction. The optical disc drive apparatus is configured such that the objective lens is offset-displaced by the control means for the optical discs described above, and the offset displacement amount of the objective lens is set to 0 for the DVD-based optical disc and the CD-based optical disc having no aperiodic structure. It is.

A hologram laser is used in the CD optical system (claim 19).

In FIG. 15, a divergent light beam emitted from a semiconductor laser 41A, which is a light source for a DVD optical disk, is converted into a substantially parallel light beam by a collimator lens 42A, and a first beam splitter 43A and a second beam splitter 43B are sequentially arranged. After passing through, the deflection prism 44 deflects the optical path by 90 degrees, and the objective lens 45 allows the optical disc M to pass through.
A light spot is formed on the recording surface through a transparent substrate of D (DVD type optical disk). Information is reproduced, recorded, or erased by this light spot.

The light beam reflected by the recording surface becomes a return light beam,
The light beam is made into a substantially parallel light beam again by the objective lens 45, is deflected by the deflection prism 44, is transmitted through the second beam splitter 43B, is reflected by the first beam splitter 43A, is focused by the detection lens 46A, and is formed as a light receiving means. The light beam is incident on the light receiving element 47A, and an information signal and a servo signal are generated.

The hologram laser 410 used in the CD optical system is described as follows: "The semiconductor laser chip 411 which is a CD light source, and the hologram 4 which functions as a beam splitter.
12. The light receiving element 413 as a light receiving means is integrated.

The divergent light beam from the semiconductor laser chip 411 passes through the hologram 412 and then is coupled to the coupling lens 42.
The light beam is converted into a substantially parallel light beam or a “slightly divergent light beam” by C, reflected by the second beam splitter 43B, the optical path thereof is deflected by 90 degrees by the deflection prism 44, and converted into a convergent light beam by the objective lens 45, and the optical disc MD ( It is transmitted through a transparent substrate of a CD type optical disc) and condensed as a light spot on the recording surface. "Reproduction of information" is performed by this light spot.

The light beam reflected on the recording surface of the disk becomes a return light beam, which is again made into a substantially parallel light beam or a "slightly converging light beam" by the objective lens 45, is deflected by the deflection prism 44, and is reflected by the second beam splitter 43B. After passing through the coupling lens 42C, it is diffracted by the hologram 412 and enters the light receiving element 413 to generate an information signal and a servo signal.

As described above, the optical disc drive apparatus of FIG. 15 is described as follows: "For a DVD type optical disc having an aperiodic structure, a control means (not shown in FIG.
The objective lens 45 is offset and displaced as shown in FIGS. 12, 13 and 14, but the offset displacement of the objective lens is performed for a DVD type optical disc and a CD type optical disc having no aperiodic structure. The amount is set to 0, and the offset displacement of the objective lens is not performed.

FIG. 16A shows the "relationship between the inclination of the hologram laser and the offset of the push-pull signal". When the hologram laser 410 has a large inclination (the inclination of the principal ray of the emitted light beam with respect to the optical axis of the coupling lens 42C), the offset of the push-pull signal becomes proportionally large. In the hologram laser 410, “the semiconductor laser chip 411 of the light source, the hologram 412, the light receiving element 41
"Position 3" is predetermined, so "offset of push-pull signal" when CD type optical disk is used
Is difficult to adjust.

In the optical pickup shown in FIG. 15, the "tilt of hologram laser 410 (position of hologram laser)" is adjusted when the optical pickup is assembled, and "push-pull signal offset is removed" (claim). 20).

FIG. 16B shows "relationship between the position of the objective lens and the offset of the push-pull signal". As described above, it is difficult for the hologram laser 410 to adjust the offset of the push-pull signal. In this case, when the optical pickup of FIG. 15 is assembled, "the position of the objective lens is moved together with the actuator so as to be assembled so as to remove the offset of the push-pull signal generated by the hologram laser 410". That is, the DVD system is assembled after the CD system is assembled.

In other words, the reference position where the offset displacement amount in the objective lens becomes 0 is adjusted at the time of assembling the optical pickup, so that the tracking with respect to the optical disk having no aperiodic structure can be appropriately performed (claim). Item 21).

[0142]

As described above, according to the present invention, a novel optical disk drive device can be realized. The optical disk drive device of the present invention can prevent the quality of the information signal component from the aperiodic structure from deteriorating to a required level or less in a band having a higher frequency than the groove tracking servo band, and also realizes an appropriate groove tracking servo. You can
The objective lens actuator is not destroyed.

When an optical disc having an aperiodic structure and an optical disc having no aperiodic structure are used, in the latter case, the groove tracking servo can sufficiently follow the high speed rotation of the optical disc.

[Brief description of drawings]

FIG. 1 is a diagram for explaining an aperiodic structure in an optical disc.

FIG. 2 is a diagram for explaining a light receiving unit.

FIG. 3 is a diagram for explaining a signal obtained from the light receiving unit of FIG.

FIG. 4 is a diagram for explaining C / N of a wobble signal.

FIG. 5 is a diagram for explaining one embodiment of an optical disk drive device.

FIG. 6 is a diagram showing an example of an objective lens actuator.

FIG. 7 is a diagram for explaining an example of a specific configuration of control means in FIG.

FIG. 8 is a flowchart illustrating generation of offset current in an offset current generation unit in FIG.

FIG. 9 is a diagram showing a typical example of the relationship between the offset displacement amount and the tilt amount of the objective lens, and the relationship between the offset displacement amount and the wavefront aberration of the objective lens.

FIG. 10 is a diagram showing an example of an optical pickup having two semiconductor lasers.

FIG. 11: 1 of optical pickup having two light receiving means
It is a figure which shows an example.

FIG. 12 is a block diagram showing an example of implementation of an optical disk drive device according to a twelfth aspect.

FIG. 13 is a block diagram showing an example of implementation of the optical disk drive device according to claim 14;

FIG. 14 is a block diagram showing an example of implementation of an optical disk drive device according to claim 16;

FIG. 15 is a diagram showing an example of an optical pickup used in the optical disc drive device according to claim 19;

FIG. 16 is a diagram for explaining the relationship between the tilt of the hologram laser and the offset of the push-pull signal, and the relationship between the position of the objective lens and the offset of the push-pull signal.

[Explanation of symbols]

41 Semiconductor laser 42 Collimating lens 43 beam splitter 45 Objective lens 46 Detection lens 47 light receiving means Optical disc as MD optical recording medium

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 5D117 AA02 CC07 HH01                 5D118 AA13 BA01 BB01 BB03 BB07                       CD03 CD11 DA33 DA35 DC03                 5D119 AA28 BA01 BB01 BB02 BB04                       EA02 EC47 FA02 FA05 FA08                       KA04

Claims (21)

[Claims] 1. Information from a non-periodic structure in the radial direction of an optical disc, which is obtained by converging a light beam on a recording surface of an optical disc having wobbles and / or land pre-pits to record / reproduce / erase information. The offset displacement that shifts the objective lens of the optical pickup in the tracking direction so that the quality of the information signal component from the aperiodic structure does not deteriorate below the required level in the frequency band higher than the groove tracking servo band. A current that has a control means for controlling the amount of the current, and that the current passing through the objective lens actuator to realize the offset displacement amount is smaller than the allowable upper limit current value of the objective lens actuator and that the tracking displacement of the objective lens is possible. An optical disk drive device characterized in that a value (≠ 0) is set. 2. The optical disk drive device according to claim 1, wherein the tilt of the objective lens due to the resonance of the objective lens actuator causes the current flowing through the objective lens actuator to realize an offset displacement amount to be equal to or less than an allowable upper limit value. An optical disk drive device characterized in that 3. The optical disk drive device according to claim 1, wherein a current flowing through the objective lens actuator to realize the offset displacement amount is determined from the size of the movable range of the objective lens actuator in the tracking direction of the optical disk. An optical disk drive device, wherein an amount excluding the average maximum eccentricity amount is set as a current value that is realized as an offset displacement amount. 4. The optical disc drive apparatus according to claim 1, wherein a current passing through an objective lens actuator for realizing an offset displacement amount, a deterioration of the wavefront aberration due to the offset displacement of the objective lens, is a maximum allowable range of the deterioration of the wavefront aberration. An optical disk drive device characterized by being set to a current value within the range. 5. Information from a non-periodic structure in the radial direction of the optical disc by converging a light beam on a recording surface of an optical disc having wobbles and / or land prepits to perform one or more of recording, reproducing and erasing of information. The offset displacement that shifts the objective lens of the optical pickup in the tracking direction so that the quality of the information signal component from the aperiodic structure does not deteriorate below the required level in the frequency band higher than the groove tracking servo band. An optical disk drive device comprising a control means for controlling the amount, and optimizing the offset displacement amount of the objective lens according to the type of the optical disk. 6. The optical disk drive device according to claim 5, wherein usable optical disks are CD-R, CD-RW, and DV.
D + R, DVD + RW, DVD-RAM, DVD-R,
An optical disk drive device characterized by comprising two or more kinds of DVD-RW and the like, and optimizing an offset displacement amount of an objective lens corresponding to them. 7. The optical disk drive apparatus according to claim 5 or 6, wherein information can be reproduced on an optical disk that does not have an aperiodic structure in the radial direction, and does not have the aperiodic structure. An optical disk drive device, wherein when an optical disk is used, the offset displacement amount of the objective lens of the optical pickup is set to 0. 8. The optical disk drive device according to claim 7, wherein the optical disk is a CD-DA, a CD-ROM, or a DVD-RO.
An optical disc drive device wherein the offset displacement amount of the objective lens of the optical pickup is set to 0 when M or the like. 9. The optical disk drive device according to any one of claims 5 to 8, wherein the optical pickup has two or more semiconductor lasers having mutually different emission wavelengths, and the offset displacement amount of the objective lens is
An optical disk drive device characterized by being optimized according to each semiconductor laser. 10. The optical disk drive device according to claim 9, wherein a detection unit for detecting a return light beam from the optical disk is shared by the light beams emitted by the respective semiconductor lasers. . 11. The optical disk drive device according to claim 9, wherein the optical disk drive device has two or more detection units for detecting a return light beam from the optical disk. 12. Information from a non-periodic structure in the radial direction of the optical disc by converging a light beam on the recording surface of the optical disc having wobbles and / or land prepits to perform one or more of recording, reproducing and erasing of information. The offset displacement that shifts the objective lens of the optical pickup in the tracking direction so that the quality of the information signal component from the aperiodic structure does not deteriorate below the required level in the frequency band higher than the groove tracking servo band. A control unit for controlling the quantity, the control unit generating a control signal for controlling the objective lens actuator so that the quality of the information signal component from the aperiodic structure is the best; A limiter for limiting the maximum value of the control signal output from the unit according to a predetermined limiter value. Optical disk drive device. 13. The optical disk drive device according to claim 12, wherein a predetermined limit value limited by the limiter is a current value of a current flowing to the objective lens actuator to realize an offset displacement amount, and an allowable upper limit current of the objective lens actuator. An optical disk drive device, which is smaller than the value and is set as a value that is realized as a current value (absolute value of current value> 0) that enables tracking displacement of the objective lens. 14. The optical disk drive device according to claim 12 or 13, further comprising limit value generating means adapted to a plurality of types of optical pickups and generating a limit value according to the type of objective lens actuator of the optical pickup used. An optical disk drive device having. 15. The optical disk drive device according to claim 14, wherein the control section causes the limit value generation means to generate a limit value in accordance with an actuator identification signal from the optical pickup. 16. The optical disk drive device according to any one of claims 12 to 15, wherein the quality of the information signal component from the aperiodic structure is degraded to a required level or less depending on the offset displacement of the objective lens due to the limiter value. An optical disk drive device, wherein the control unit outputs a signal to that effect when it cannot be avoided. 17. The optical disk drive device according to any one of claims 12 to 15, wherein the control unit controls the offset displacement according to the limit value,
An optical disk drive device, which outputs a signal indicating the degree of quality of an information signal component from an aperiodic structure. 18. A light beam is focused on a recording surface of a DVD or CD optical disk to reproduce at least information, information is read from an aperiodic structure in the radial direction of the optical disk, and a frequency is read from a groove tracking servo band. In the high frequency band of the above, a control means is provided for controlling the offset displacement amount for offset displacement of the objective lens of the optical pickup in the tracking direction so that the quality of the information signal component from the aperiodic structure does not deteriorate below the required level. , For DVD type optical discs with aperiodic structure,
The objective lens is offset-displaced according to the control by the control means, and a DVD type optical disc having no aperiodic structure and C
An optical disk drive device wherein the offset displacement amount of the objective lens is set to 0 for a D-system optical disk. 19. The optical disk drive device according to claim 18, wherein a hologram laser is used for a CD optical system. 20. The optical disk drive device according to claim 19, wherein the offset of the push-pull signal is removed by adjusting the position of the hologram laser at the time of assembling the optical pickup. 21. The optical disk drive device according to claim 19 or 20, wherein the reference position at which the offset displacement amount in the objective lens is 0 is adjusted at the time of assembling the optical pickup,
An optical disk drive device, which is adapted to appropriately perform tracking on an optical disk having no aperiodic structure.