JPH11203703A - Skew adjustment device - Google Patents

Abstract

(57) [Summary] [Problem] Even in the case of a rewritable optical disk, or even if there is an area such as a recorded part and an unrecorded part on the same optical disk, accurate skew adjustment is performed and the type of the optical disk is To provide a skew adjustment device for an optical disk device, which is determined. A skew sensor detects a skew in at least a part including a recorded portion and an unrecorded portion of an optical disk in advance in a radial direction on the basis of a maximum value and a minimum value of a sum signal S of each light receiving portion of the skew sensor. A reference value S for discriminating between a recorded portion and an unrecorded portion of the optical disc.
r, and at the time of recording or reproduction of the optical disk, the sum signal S of each light receiving section of the skew sensor is monitored, and the sum signal is compared with the reference value. , The skew adjustment is performed based on the detection signal of the skew sensor 30, and the skew adjustment is performed according to the control stage of ignoring the detection signal of the skew sensor when corresponding to the recording portion.

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 recording or reproducing data on or from an optical disk, and more particularly to a skew adjusting apparatus for an optical disk.

[0002]

2. Description of the Related Art Conventionally, an optical pickup for reproducing an optical disk is constructed, for example, as shown in FIG. FIG.
, The optical pickup 1 comprises a lens holder 3 having an objective lens 2 attached to a tip thereof, and a fixing portion 4 for supporting the lens holder 3 movably in two axial directions.
And a biaxial base 5 to which the fixing part 4 is attached, and a driving means (not shown) for driving the lens holder 3 in biaxial directions.
And is composed of

Here, the lens holder 3 is, for example, provided by two pairs of elastic support members 6 having one end fixed to both sides of the lens holder 3 and the other end fixed to the fixing portion 4.
It is supported so as to be movable in two directions perpendicular to the fixed part 4, that is, in a tracking direction perpendicular to the paper surface and a focusing direction indicated by reference symbol Fcs. Also, the objective lens 2
A light beam from a light emitting unit (not shown) is focused on a signal recording surface of the optical disk, and return light from the optical disk 7 is imaged as a spot on a light receiving surface of a photodetector via an optical system (not shown).

Thus, based on the detection signal from the photodetector, a reproduction signal of the optical disk is detected, and a tracking error signal and a focus error signal are detected. Thus, the driving of the driving unit is controlled based on the tracking error signal and the focus error signal.

[0005] The optical pickup 1 configured as described above.
According to the above, the lens holder 3 is moved in the tracking direction and the focusing direction Fcs by being externally driven and controlled by the driving means by the tracking servo and the focus servo as described above. Thus, the objective lens 2 attached to the lens holder 3 is appropriately moved in the focusing direction and the tracking direction. As a result, the return light from the optical disk accurately forms a spot on the light receiving surface of the photodetector, and a reproduction signal of the optical disk is detected based on the detection signal from the photodetector.

[0006] In recent years, the density of optical discs has been increasing in recent years, for example, for recording image information and for storing huge data. When reproducing high-density optical discs, conventional optical discs are ignored. Radial skew of the resulting optical disk has become a problem in terms of reliability of the detection signal and securing of a system margin.

For this reason, as shown in FIG. 8, for example, by mounting a skew sensor (also referred to as a tilt sensor) 8 on the two-axis base 5, the skew is detected by the skew sensor 8. You. As shown in FIG. 9, the skew sensor 8 includes an LED (light emitting diode) 8a as a light emitting element and a photodetector 8b as a light receiving element. As shown in FIG. 10, the photodetector 8b includes two light receiving sections A and B divided in the radial direction of the optical disk 7.

Accordingly, the light emitted from the LED 8a is reflected on the optical disk and enters the photodetector 8b, so that the reflected light spot from the optical disk 7 can be detected when the optical disk 7 has no radial skew. Table 8
It falls on the dividing line b, but if there is a radial skew, it deviates from this dividing line. Accordingly, by taking the difference signal Sd (Sd = SA−SB) between the output signals of the light receiving units A and B divided into two by the subtractor 9a shown in FIG. 8, the radial skew of the optical disk 7 is reduced. Will be detected. Note that the difference signal Sd is generally set so as not to vary with the reflectance of the optical disk 7.
For example, the signal is standardized by division by the sum signal S (S = SA + SB) of the two light receiving units by the adder 9b shown in FIG. 10 by the divider 9c shown in FIG.

[0009]

By the way, recently, rewritable optical disks and so-called write-once optical disks have been widely used as optical disks. Since the reflectance of the optical disk surface is substantially constant at, for example, about 60% or more, the sum signal S of the photodetector 8b is substantially constant and the difference signal Sd1 is It will change slowly.

On the other hand, when there is a recorded portion on a part of the optical disk, the reflectance of the recorded portion becomes smaller than the reflectance of the unrecorded portion.
As indicated by reference numerals P and Q at 1, the sum signal S of the photodetector 8b drops and the difference signal Sd also changes greatly. This is, as shown in FIG. 12, from an unrecorded portion having a relatively high reflectivity (10% in the case shown) to a recorded portion having a relatively low reflectivity (5% in the case shown), or from the recorded portion. This is because the return light from the optical disk 7 is incident on the photodetector 8b divided in the radial direction of the optical disk when moving to the unrecorded portion, and the sum signal S and the difference signal Sd fluctuate greatly. Thus, in the case of a rewritable optical disc, when an unrecorded portion and a recorded portion are mixed, when the traversal from the unrecorded portion to the recorded portion or from the recorded portion to the unrecorded portion, the output signal of the skew sensor is There is a problem that a large fluctuation causes an error in the detection of the skew amount, and the accurate skew amount cannot be detected. In the case of a write-once optical disk, as shown in FIG. 13, the reflectance is approximately 60% or more at a wavelength of about 700 nm or more, but is substantially constant.
If the wavelength is less than that, the reflectance becomes about 20% or less, which has wavelength dependency. For this reason, in order to reliably determine the write-once optical disk, it is necessary to consider this point. Further, when there is a flaw, dust, or the like on the optical disk, the difference signal Sd similarly fluctuates greatly, and similarly, an error occurs in the detection of the skew amount.

Furthermore, in the case of a rewritable optical disk, it is desirable to write data in order from the innermost side of the optical disk, for example, in order to shorten the access time due to data concentration, that is, to optimize the access time. However, due to such optimization, recording and erasing of data are frequently repeated in the innermost area of the optical disk, and the reflectivity of the optical disk including a change with time cannot be predicted. For this reason, there is a possibility that the detection signal of the skew sensor in the innermost area of such an optical disc becomes an erroneous signal.

On the other hand, an optical disk apparatus having means for determining the type of an optical disk is also known, and skew adjustment can be performed in accordance with the determined type of the optical disk. In addition to the above, there is a disadvantage that the structure is complicated, and it is not possible to solve the above-described problems in the recorded portion and the unrecorded portion on the same type of disc.

In view of the above points, the present invention provides an accurate skew even in the case of a rewritable optical disk, or even if there is a recorded portion and an unrecorded portion, or an area where a scratch or dust exists on the same optical disk. Adjustment is performed, and the type of optical disk is determined using a skew sensor.
It is an object of the present invention to provide a skew adjustment device for an optical disk device.

[0014]

According to the present invention, according to the present invention, an optical disk is irradiated with light through a light converging means, and return light from a signal recording surface from the optical disk is emitted. A skew sensor that is fixed to the optical pickup to be detected and detects the inclination of the optical disc; a skew adjustment mechanism that performs skew adjustment of the optical pickup based on a detection signal of the skew sensor; and the skew sensor. A light emitting unit for irradiating the surface of the optical disk with light, and a light detector comprising a light receiving unit divided into two to detect reflected light from the optical disk, and a difference signal between the two divided light receiving units. The skew of the optical disk is detected based on the skew amount of the optical disk. By performing the recording portion and at least a portion at skew detection contain an unrecorded portion, based on the maximum value and the minimum value of the sum signal of the light receiving portions of the skew sensor,
A reference value setting step of setting a reference value for discriminating between a recorded portion and an unrecorded portion of the optical disc; and, during recording or reproduction of the optical disc, monitoring the sum signal of each light receiving section of the skew sensor, and calculating the sum signal. A control step of performing skew adjustment based on a detection signal of the skew sensor when corresponding to an unrecorded portion of the optical disk, and ignoring a detection signal of the skew sensor when corresponding to a recorded portion, as compared with the reference value. Thus, the skew adjustment is achieved by the skew adjustment device.

According to the first aspect of the present invention, before recording or reproduction of the optical disk, in the reference value setting step, the recorded portion and the unrecorded portion of the optical disk are determined based on the sum signal detected by the skew sensor. A reference value for Then, when recording or reproducing the optical disc, the sum signal of the skew sensor is compared with the reference value in the control stage. If the sum signal is higher than the reference value, it is an unrecorded portion of the optical disc. And determine
Skew adjustment is performed based on the difference signal of the skew sensor. On the other hand, when the sum signal is lower than the reference value, the signal is determined to be a recording portion of the optical disk, and the detection signal of the skew sensor is ignored. Thereby, the skew adjustment is performed based on, for example, the immediately preceding detection signal of the skew sensor.

Therefore, for example, in the case of a rewritable optical disk, even if the detection signal of the skew sensor suddenly decreases due to the decrease in the reflectance at the recording portion, the skew is adjusted based on the detection signal of the skew sensor. Since there is no skew adjustment, a malfunction of the skew adjustment can be avoided. In this way, at least the objective lens of the optical disk device is held substantially perpendicular to the optical disk, and the effects of skew of the optical disk are eliminated, so that the recording or reproduction of the optical disk is performed accurately.

According to the configuration of claim 2, the reference value is:
If the maximum value or the minimum value of the sum signal is set as a constant multiple, the reference value is easily set.

According to the third aspect of the present invention, when the skew detection in the reference value setting step is performed from the innermost circumference to the outermost circumference of the optical disc, the unrecorded portion and the recorded portion over the entire radial direction of the optical disc. Will be completely detected.

According to the fourth aspect of the present invention, the skew detection in the reference value setting step includes monitoring the reproduction signal of the optical pickup so as to include the recorded portion and the unrecorded portion of the optical disk in the radial direction of the optical disk. When the skew detection is performed in a part, the skew detection is performed in a short time because only the skew detection in a part of the optical disk in the radial direction is sufficient.

According to the fifth aspect of the present invention, when the difference signal of each light receiving portion of the skew sensor is normalized by multiplying by a constant determined based on the sum signal according to the optical disc, As compared with the case where the sum signal is standardized by the conventional sum signal, stable normalization that is not affected by the fluctuation of the sum signal during the traversal between the recorded portion and the unrecorded portion can be obtained.

According to the sixth aspect of the present invention, at the time of reproduction of the rewritable optical disk, the sum signal of each light receiving section of the skew sensor is monitored, and the sum signal is compared with a reference value to correspond to a recording portion of the optical disk. Skew adjustment based on the detection signal of the skew sensor only when
Reproduction of the recorded portion of the rewritable optical disk is surely performed.

According to the seventh aspect of the present invention, when the skew adjustment is not performed at a distance corresponding to the spot diameter of the skew sensor from the innermost circumference of the optical disk, the spot of the skew sensor is completely formed on the optical disk. The disturbance of the sum signal and the difference signal when the convergence is not performed is eliminated, and more accurate skew adjustment is performed.

According to the eighth aspect of the present invention, the skew detection in the reference value setting step is performed only at a plurality of positions in the radial direction of the optical disk, so that the sum signal and the difference signal with respect to the radial position of the optical disk are sampled. If a reference value for discriminating between a recorded portion and an unrecorded portion of the optical disc is set based on the sampled sum signal, the reference value setting in the reference value setting step is performed by sampling. It will be done more easily and in a shorter time.

According to the eleventh aspect of the present invention, there is provided an optical pickup for irradiating an optical disk with light through a light focusing means and detecting return light from a signal recording surface from the optical disk. A skew sensor that is fixedly arranged and detects the inclination of the optical disk; and a skew adjustment mechanism that adjusts the skew of the optical pickup based on the detection signal of the skew sensor. A light emitting unit for irradiating light to the surface of the optical disc, and a photodetector comprising a light receiving unit divided into two so as to detect reflected light from the optical disk, and further, a sum signal of the light receiving unit divided into two. Is compared with the disc type reference value by a skew adjusting device provided with a discriminating circuit for discriminating the type of the optical disc.

According to the ninth aspect or the eleventh aspect, in the reference value setting step, it is determined whether or not the optical disk is a rewritable optical disk based on a sum signal obtained by skew detection. Since the type of the optical disk is determined without providing a separate optical disk determination unit, the light source of the optical pickup is adjusted to the optimum light intensity and the gain of the photodetector is adjusted according to the type of the optical disk. At the same time, more accurate skew adjustment is performed.

According to the twelfth aspect of the present invention, the disc type reference value used in discriminating the disc type by the discriminating circuit is set in advance and stored in the memory, thereby obtaining the disc type. Is easily determined.

According to the thirteenth aspect, the light emitting portion of the skew sensor emits light having a wavelength of 700 nm or more, so that even if the optical disk is a write-once optical disk, a high reflectance is obtained. Can be easily determined.

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to FIGS. still,
Since the embodiments described below are preferred specific examples of the present invention, various technically preferred limitations are added.
The scope of the present invention is not limited to these embodiments unless otherwise specified in the following description.

FIG. 1 shows an embodiment of an optical disk device incorporating a skew adjusting device according to an embodiment of the present invention. In FIG. 1, an optical disk device 10 includes a spindle motor 12 as a driving unit that rotationally drives an optical disk 11, and an optical pickup 13. Here, the spindle motor 12 is driven and controlled by the optical disk drive controller 14, and is rotated at a predetermined rotation speed. The optical disc 11 can select and reproduce a plurality of types of optical discs.

The optical pickup 13 irradiates the signal recording surface of the rotating optical disk 11 with light to record a signal or to detect return light from the signal recording surface. A reproduced signal based on the return light is output to the signal demodulator 15.

As a result, the recording signal demodulated by the signal demodulator 15 is subjected to error correction through an error correction circuit 16 and sent to an external computer or the like via an interface 17. With this, the external computer etc.
A signal recorded on the optical disk 11 can be received as a reproduction signal.

The optical pickup 13 is connected to a head access control unit 18 for moving the optical pickup 13 to a predetermined recording track on the optical disk 11 by a track jump or the like. Further, at the moved predetermined position, a biaxial actuator that holds an objective lens as a light focusing unit of the optical pickup 13 is provided.
A servo circuit 19 for moving the objective lens in the focusing direction and the tracking direction is connected.

FIG. 2 shows a configuration example of the optical pickup 13. In FIG. 2, the optical pickup 13
A lens holder 22 having an objective lens 21 as a light focusing means attached to the tip thereof;
Fixing part 23 supporting movably in two axial directions
And a biaxial base 24 to which the fixing portion 23 is attached, a driving unit (not shown) for driving the lens holder 22 in the biaxial directions, and a skew sensor 30.

Here, the lens holder 22 is, for example,
Two directions perpendicular to the fixed part 23, that is, a tracking direction perpendicular to the paper surface, by two pairs of elastic support members 25 having one end on both sides of the lens holder 22 and the other end fixed to the fixed part 23. And is supported so as to be movable in a focusing direction indicated by reference symbol Fcs. The objective lens 21 condenses a light beam from a light emitting unit (not shown) on a signal recording surface of the optical disk, and returns light from the optical disk 11 to a light receiving surface of a photodetector via an optical system (not shown). To form an image as a spot.

Thus, based on the detection signal from the photodetector, the reproduction signal of the optical disk is detected, and the tracking error signal and the focus error signal are detected. Thus, the tracking servo and the focus servo are performed by the driving unit based on the tracking error signal and the focus error signal.

Further, a skew sensor 30 for detecting a radial skew amount of the optical disk 11 is provided on the optical pickup 13. The skew sensor 30 includes an LED 31 as a light emitting element and a photodetector 32 as a light receiving element, as shown in FIG. 3, similarly to the skew sensor 8 in the conventional optical pickup 1 shown in FIG. The photodetector 32 includes two light receiving portions A and B divided into two in the radial direction of the optical disc 11. The LED 31 is preferably configured to emit light having a wavelength of, for example, about 700 nm or more.

FIG. 4 shows the configuration of the skew adjusting device. In FIG. 4, the skew adjustment device 40 includes an arithmetic circuit 41 to which signals Sa and Sb from the light receiving units A and B of the photodetector 32 of the skew sensor 30 are input, and a sum signal and a difference signal from the arithmetic circuit 41. And a skew adjustment mechanism 43 that performs skew adjustment based on the skew adjustment signal from the control circuit 42.

Here, the operation circuit 41 and the control circuit 42
Is configured, for example, as shown in FIG. In FIG. 5, the arithmetic circuit 41 includes an adder 41a and a subtractor 41b to which the output signals Sa and Sb from the respective light receiving units A and B are input in reverse to the non-inverted input and the inverted input, respectively.
Sum signal S (S = Sa + Sb) from these adders 41a
And the difference signal Sd (Sd = Sa−S) from the subtractor 41b.
b) is input and the difference signal Sd is divided by the sum signal S, so that a divider 41c for calculating the normalized difference signal Sd1 is obtained. Further, the sum signal S from the adder 41a and the disc type reference value M are obtained. And a comparator 41d to be inputted. The disc type reference value M is stored in the memory 41e in advance according to the type of the optical disc to be determined, and is read out when necessary, and is read out by the comparator 41.
d. Thus, the comparison result of the comparator 41d is given to the control circuit 42, and the type of the optical disc is determined as described later. As a result, the memory 41e and the comparator 41d
These constitute a discriminating circuit as discriminating means for the optical disk.

The control circuit 42 generates a skew adjustment signal based on the difference signal Sd1 calculated by the calculation circuit 41 so that the skew angle becomes zero. that time,
The control circuit 42 outputs the output signals Sa,
The difference signal Sd is normalized in order to eliminate the influence of the variation of Sb. In this case, the difference signal Sd is not normalized by the sum signal S, but is multiplied by a gain G corresponding to the optical disc 11 to obtain:
Control is performed using Sd1 (Sd1 = Sd × G) as a skew detection signal. Note that this gain G
Is appropriately determined based on the sum signal of the skew sensor 30 when the optical disk 11 is inserted, and the same gain G is used until the optical disk 11 is replaced. In addition,
The gain G is selected and reset by the control circuit 42 from a preset value according to the type of the optical disc determined as described later, according to the determination result.

Further, the control circuit 42
Is a rewritable optical disc, a reference value Sr for discriminating between a recorded portion and an unrecorded portion of the optical disc is generated based on the sum signal S of the skew sensor 30 in advance. The sum signal S is compared with a reference value Sr to generate a skew adjustment signal. In this case, the reference value Sr is determined by first performing skew detection from the innermost circumference to the outermost circumference in the radial direction of the optical disc 11,
The maximum value and the minimum value of the sum signal S are detected, and for example, Smax
Is set to α times or β times the minimum value. The value α or β is appropriately set in advance so that a recorded portion and an unrecorded portion of the rewritable optical disk can be accurately determined.
The control circuit 42 monitors the sum signal S of the skew sensor 30 at the time of recording or reproduction on the optical disk 11, and based on the detection signal of the skew sensor only when the sum signal S exceeds the reference value Sr. , And outputs a skew adjustment signal. If the sum signal S is equal to or smaller than the reference value Sr, the control circuit 42 ignores the detection signal from the skew sensor and outputs a skew adjustment signal based on, for example, the detection signal from the immediately preceding skew sensor. It has become.

The skew adjusting mechanism 43 includes a control circuit 4
The skew adjustment is performed by inclining the optical pickup 13 or the biaxial base 24 or the like based on the skew adjustment signal from the optical pickup 2. Then, the operation circuit 4
1. The control circuit 42 and the skew adjustment mechanism 43 may be configured together with the optical pickup 13 or a control board of the optical disk device. Further, the control content may be realized by a CPU and predetermined software, or may be realized by an electronic circuit that performs an equivalent control function.

The optical disk device 10 according to the present embodiment is
The skew adjustment is configured as described above based on the flowchart shown in FIG. 6 as follows. First, when an optical disk is loaded on the optical disk device 10, the skew adjusting device 40 of the optical disk device 10 moves the optical pickup 13 in the radial direction of the optical disk 11 by the skew sensor 30 and moves the optical disk 13 to the maximum position in step ST1. Skew detection is performed from the inner circumference to the outermost circumference (step ST
2). Here, the calculation of the sum signal S and the difference signal Sd by the calculation circuit 41 is performed continuously, but for example, at an appropriate interval in the radial direction of the optical disk 11, for example, 0.5.
The sampling may be performed at a plurality of points at intervals of about 1 mm to 1 mm. In this case, the sampled sum signal S and difference signal Sd are temporarily stored together with the radial position of the optical disc 11 at the time of sampling,
The skew state of the optical disk 11 is learned. Thereby, the number of data to be processed by the control circuit 42 can be reduced, and the load can be reduced, thereby enabling higher-speed processing.

The arithmetic circuit 41 outputs the output signals Sa, Sb from the skew sensor 30 based on the skew detection.
, The sum signal S and the difference signal Sd are calculated. Subsequently, the control circuit 42 sets a reference value Sr from the sum signal S from the arithmetic circuit 41, for example, as α times the maximum value or β times the minimum value, and gives the reference value Sr to the control circuit 42. On the other hand, the comparator 41d determines the type of the optical disk based on the sum signal S as described later, reads a gain G corresponding to the type from the memory 41d, and the control circuit 42 resets the gain G. I do.

After the reference value Sr is set in this way, recording or reproduction of the optical disk 11 is performed in step ST4. At this time, in step ST5, skew detection is performed by the skew sensor 30, for example, at predetermined time intervals. Then, in step ST6, the control circuit 42 compares the sum signal S calculated by the arithmetic circuit 41 based on the output signal from the skew sensor 30 with a reference value Sr. If larger, step ST7
Then, it is determined that the portion is an unrecorded portion of the rewritable optical disk 11, and a skew detection signal Sd1 obtained by multiplying the difference signal Sd by the gain G is output to the skew adjustment mechanism 43 as a skew adjustment signal. On the other hand, when the sum signal S is smaller than the reference value Sr, in step ST8, it is determined that the recording portion is on the rewritable optical disk 11, and the difference signal Sd is ignored. Is output to the skew adjustment mechanism 43 as a skew adjustment signal at this time.

Thus, the skew adjustment described above is repeatedly performed at appropriate time intervals, so that the skew is adjusted so that the skew at the time of recording or reproduction of the optical disk 11 is always zero, and the recording of the optical disk is performed. Or, reproduction will be performed accurately.

In this case, in the case of the read-only optical disk 11, since the sum signal S is substantially constant, the skew adjustment is always performed based on the detection signal of the skew sensor. When the sum signal S fluctuates greatly, as in the case where a traverse or a scratch, dust, or the like has adhered between the unrecorded portion and the unrecorded portion, the sum signal falls below the reference value Sr. The skew adjustment based on the detection signal of the sensor is interrupted, and for example, the skew adjustment based on the immediately preceding detection signal is performed. This eliminates errors in the detection signal of the skew sensor,
A malfunction of the skew adjustment will be avoided. Also,
If the surface of the optical disc 11 has scratches, dust, or fingerprints, accurate skew adjustment will be performed even if the sum signal sharply decreases.

In the above embodiment, step ST2
The skew sensor 30 detects the skew from the innermost circumference to the outermost circumference of the optical disc 11, but is not limited to this, and the skew detection reflects the unrecorded portion and the recorded portion of the optical disc 11 What is necessary is just to know the fluctuation of the output signal of the skew sensor 30 based on the difference between the rates. Therefore, for example, while monitoring the reproduction signal or the pit signal of the optical pickup 13, the skew sensor 30
Skew detection by the optical disk 1
Skew detection may be performed in the recorded portion and the unrecorded portion of No. 1. According to such a configuration, the skew detection in step ST2 is performed in a short time.

In the above embodiment, the type of the optical disk is determined as follows based on the flowchart of FIG. First, in step ST11, when an optical disk is inserted (loaded) into the optical disk device 10, the skew adjusting device 40 of the optical disk device 10
While moving the optical disk 11 in the radial direction, the skew sensor 30 is operated to detect the skew from the innermost circumference to the outermost circumference of the optical disk 11 (step ST1).
2). Here, in step ST13, the comparator 41d of the arithmetic circuit 41 compares the sum signal S from the arithmetic circuit 41 with the disc type reference value M previously stored in the memory 41d, and the sum signal S If the value is larger than the value M, the control circuit 42 determines in step ST14 that the optical disk is a rewritable optical disk. If the sum signal S is smaller than or equal to the reference value M, the control circuit 42 proceeds to step ST15. 42 determines that the optical disc is not a rewritable optical disc,
In step ST16, the light emission power of the light source of the optical pickup 13 is adjusted in accordance with the reflectance according to the determined type of the optical disk, and the signal from the photodetector of the optical pickup 13 is processed. The gain of the signal demodulator 15 and the like is adjusted. This makes it possible to determine the type of the optical disk without providing a separate optical disk determination unit. According to the type of the optical disk to be reproduced, the light beam having the optimum intensity can be determined according to the reflectance of the optical disk. Is applied to the signal recording surface of the optical disk 11 and the signal processing is optimally performed in accordance with the strength of the signal from the photodetector. In this case, since the LED 31 of the skew sensor 30 emits light having a wavelength of about 700 nm or more, even if the optical disk is a write-once optical disk, the type of the optical disk can be reliably determined. It has become. The disc type is determined by
It is performed independently for skew adjustment,
The order does not matter.

In the above embodiment, the skew adjustment at the time of recording or reproduction of the rewritable optical disk has been described, but only at the time of reproduction of the rewritable optical disk, for example, the control circuit 42 monitors the sum signal S. In advance, based on the output signal from the skew sensor 30 only when it is determined that it is the recording portion of the optical disc,
Skew adjustment may be performed. In this case, accurate skew adjustment is performed based on a skew detection signal from a recorded portion having a lower reflectance than an unrecorded portion.

In the above embodiment, the skew sensor 30 is configured to detect the radial skew of the optical disk 11. However, the present invention is not limited to this. It is obvious that the present invention can be applied. In this case, when the surface of the optical disc is scratched or dust or fingerprints are attached, the tangential skew is detected with higher accuracy and the skew sensor is used. Is used to determine the type of the optical disk.

[0051]

As described above, according to the present invention, even in the case of a rewritable optical disk, or even if there is an area where a recorded portion and an unrecorded portion, scratches, dust, etc. exist on the same optical disk. In addition, it is possible to provide a skew adjustment device for an optical disk device in which accurate skew adjustment is performed and the type of the optical disk is determined using a skew sensor.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an optical disc device incorporating an optical pickup provided with a skew adjustment device for implementing a skew adjustment method according to the present invention.

FIG. 2 is a schematic side view showing a configuration of an optical pickup in the optical disk device of FIG.

FIG. 3 is a schematic perspective view showing a configuration of a skew sensor in the optical pickup of FIG. 2;

FIG. 4 is a schematic block diagram illustrating a configuration of an embodiment of a skew adjustment device in the optical pickup of FIG. 2;

FIG. 5 is a circuit diagram showing a configuration example of an arithmetic circuit in the skew adjustment device of FIG. 4;

FIG. 6 is a flowchart illustrating a skew adjustment operation in the skew adjustment device of FIG. 4;

FIG. 7 is a flowchart showing a disc type discriminating operation in the skew adjusting device of FIG. 4;

FIG. 8 is a schematic sectional view showing an example of a conventional optical pickup.

9 is a schematic perspective view showing a configuration of a skew sensor in the optical pickup of FIG.

FIG. 10 is a schematic diagram showing a photodetector of the skew sensor of FIG. 9 and a signal processing circuit thereof.

FIG. 11 is a graph showing a change in a skew detection signal in an unrecorded portion of a rewritable optical disk by a conventional skew adjustment device.

FIG. 12 is a schematic diagram illustrating the occurrence of a change in a skew detection signal in a recording portion of a skew detection rewritable optical disk by a conventional skew adjustment device.

FIG. 13 is a graph showing the reflectance of a write-once optical disk.

[Brief description of reference numerals]

10 optical disk device, 11 optical disk, 1
2 ... Spindle motor, 13 ... Optical pickup, 14 ... Optical disk drive controller, 15
... Signal demodulator, 16 ... Error correction circuit, 17 ...
Interface, 18 Head access control unit, 19 Servo circuit, 21 Objective lens, 2
2 ... Lens holder, 23 ... Fixed part, 24 ...
· Biaxial base, 25 · · · elastic support member, 30 · · · skew sensor, 31 · · · LED · 32 · · · photodetector, 40 · · · skew adjustment device, 41 · · · arithmetic circuit, 41a ... Adder, 41b ... Subtractor, 41c
.., A divider, 41d, a comparator, 41e, a memory, 42, a control circuit, 43, a skew adjustment mechanism.

Claims (13)

[Claims] 1. An optical disc, which is irradiated with light through an optical focusing means and detects return light from a signal recording surface from the optical disc, and is fixedly disposed to detect an inclination of the optical disc. A skew sensor, and a skew adjustment mechanism that adjusts the skew of the optical pickup based on the detection signal of the skew sensor. The skew sensor emits light to the surface of the optical disc, and And a photodetector comprising a light receiving portion divided into two so as to detect reflected light of the optical disk. Based on a difference signal between the light receiving portions divided into two, a skew amount of the optical disc is detected, and the optical disc is rewritten. In the case of a type optical disk, at least a part including a radially recorded part and an unrecorded part of the optical disk by a skew sensor in advance A skew detection, a reference value setting step of setting a reference value for discriminating a recorded portion and an unrecorded portion of the optical disk based on the maximum value and the minimum value of the sum signal of each light receiving portion of the skew sensor; During recording or reproduction of the optical disk, the sum signal of each light receiving portion of the skew sensor is monitored, and the sum signal is compared with the reference value. A skew adjustment based on the skew sensor, and a control step of ignoring the detection signal of the skew sensor when corresponding to the recording portion.
A skew adjustment device for performing skew adjustment. 2. The skew adjusting device according to claim 1, wherein the reference value is set as a constant multiple of a maximum value or a minimum value of the sum signal. 3. The skew adjustment device according to claim 1, wherein the skew detection in the reference value setting step is performed from an innermost circumference to an outermost circumference of the optical disk. 4. The skew detection in the reference value setting step, while monitoring a reproduction signal of the optical pickup,
The skew adjusting apparatus according to claim 1, wherein the adjustment is performed in a part of the optical disk in a radial direction so as to include a recorded portion and an unrecorded portion of the optical disk. 5. The difference signal of each light receiving section of the skew sensor is:
2. The skew adjustment device according to claim 1, wherein the skew adjustment device is standardized by multiplying a constant determined based on a sum signal according to the optical disk. 6. When reproducing a rewritable optical disk, a sum signal of each light receiving section of the skew sensor is monitored, and the sum signal is compared with a reference value. The skew adjustment device according to claim 1, wherein the skew adjustment is performed based on the detection signal. 7. The skew adjustment device according to claim 1, wherein the skew adjustment is not performed at a distance from the innermost circumference of the optical disk corresponding to the spot diameter of the skew sensor. 8. A sum signal and a difference signal with respect to a radial position of the optical disk are sampled by performing skew detection at the reference value setting stage only at a plurality of positions in a radial direction of the optical disk, and the sampled sum signal is sampled. 2. The skew adjusting apparatus according to claim 1, wherein a reference value for determining a recorded portion and an unrecorded portion of the optical disk is set based on the skew. 9. The method according to claim 1, wherein in the reference value setting step, it is determined whether or not the optical disk is a rewritable optical disk based on a sum signal obtained by skew detection.
2. The skew adjusting device according to 1. 10. An optical pickup for irradiating an optical disk with light through a light focusing means and detecting return light from a signal recording surface from the optical disk, and supporting the light focusing means movably in two axial directions. A biaxial actuator, a signal processing circuit that generates a reproduction signal based on a detection signal from the optical pickup, a servo circuit that moves the light focusing unit in the biaxial direction based on the detection signal from the optical pickup, A skew sensor fixed to the optical pickup and detecting the inclination of the optical disc; a skew adjustment mechanism for adjusting the skew of the optical pickup based on a detection signal of the skew sensor; A light-emitting unit that irradiates light and a light-receiving unit that is split into two to detect reflected light from the optical disk A skew amount of the optical disk based on the difference signal between the two divided light receiving units. If the optical disk is a rewritable optical disk, the skew sensor detects the skew amount of the optical disk in advance. Skew detection is performed on at least a part including a recorded part and an unrecorded part in the radial direction, and the recorded part and the unrecorded part of the optical disk are determined based on the maximum value and the minimum value of the sum signal of each light receiving unit of the skew sensor. A reference value setting step of setting a reference value for discrimination; and, during recording or reproduction of the optical disc, monitoring a sum signal of each light receiving portion of the skew sensor, comparing the sum signal with the reference value, and The skew adjustment is performed based on the detection signal of the skew sensor when corresponding to the unrecorded portion, and the skew correction is performed when corresponding to the recorded portion. The control stage to ignore the detection signal Sa,
An optical disk device, wherein skew adjustment is performed. 11. An optical pickup which irradiates light to an optical disc through a light converging means and detects return light from a signal recording surface from the optical disc, and is fixedly arranged to detect an inclination of the optical disc. A skew sensor, and a skew adjustment mechanism that adjusts the skew of the optical pickup based on the detection signal of the skew sensor. The skew sensor emits light to the surface of the optical disc, and And a photodetector comprising a light receiving portion divided into two so as to detect reflected light of the optical disc. Further, the sum signal of the light receiving portion divided into two is compared with a disc type reference value, and A skew adjustment device comprising a determination unit for determining a type. 12. The skew adjusting apparatus according to claim 11, wherein the disc type reference value is set in advance and stored in a memory. 13. The light emitting unit of the skew sensor is 700n.
2. A light source having a wavelength of at least m.
The skew adjusting device according to claim 1.