JPH1131328A - Disk recording and reproducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a disk recording/reproducing device which is stabilized in the amplitude of Adip signals, excellent in high volume productivity and can realize good spindle servo by forcibly applying the focus offset in the direction of increasing the amplitude of Adip signals in advance and performing focus adjustment after changing the shape of the light spot on the information recording medium at the focus adjustment of an optical head. SOLUTION: This device is provided with a focus error calculating means 29 which calculates the optimum focusing point based on a focus error signal and a focus error applying means 30 which injects a DC signal into the optical head in response to the output signal of the results of calculation. In the case of the focus adjustment of the optical head, the focus of the optical head is adjusted after changing the focusing direction and position of the object lens in advance by the focus error applying means 30.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disk recording / reproducing apparatus which projects a light spot on a disk-shaped recording medium and optically records / reproduces information.

[0002]

2. Description of the Related Art In recent years, disk recording and reproducing apparatuses have
-Applications such as multi-laser players for MD, CD, and Hi-Vision have been diversified year by year, and the density, performance, quality, and added value have been increasing. Especially in a disk playing device using a recordable magneto-optical medium,
Demand for portable and on-vehicle applications is on the rise, and there is a need for even smaller, thinner, higher-performance and lower-cost products. The present invention relates to focus adjustment of an optical head in a disk recording / reproducing apparatus for an optical disk.

Conventionally, there have been many reports on techniques relating to optical heads for magneto-optical disks.

Hereinafter, a conventional optical head for a magneto-optical disk will be described with reference to the drawings.

FIGS. 7 and 8 are a schematic structural view of a conventional optical head and a diagram for explaining the operation principle thereof. In FIG. 7, 1 is a semiconductor laser, 2 is a collimating lens, 3 is a diffraction grating, 4 is a composite element composed of a beam splitter 4a, a polarization splitting element 4b, and a folding mirror 4c, 5 is an objective lens, and 6 is magneto-optics. An information recording medium having an effect and having a wobble signal, 7 is a light receiving element for monitoring, 8 is a convex lens, 9 is a concave cylindrical lens, 10 is a holding member, 11 is a multi-split photodetector, and 12 and 13 are light spots. Focus, 14 is the multi-segment photodetector 11
A main beam (P-polarized) formed on the upper surface; a main beam (S-polarized) formed on the multi-segmented photodetector 11;
Reference numeral 16 denotes a main beam (P + S polarized light) formed on the multi-segmented photodetector 11, reference numeral 17 denotes a light spot of the preceding beam among the sub beams, and reference numeral 18 denotes a light spot of the subsequent beam among the sub beams.

FIG. 8 shows the multi-segment photodetector 1 shown in FIG.
1 is a diagram showing each light receiving area, 19 is a quadrant light receiving area, 20 is a preceding beam light receiving area, 21 is a succeeding beam light receiving area, 22a and 22b are information signal light receiving areas, 23 is a subtractor, and 24 is an adder. It is a vessel.

The operation of the above-described conventional example will be described below.

The light emitted from the semiconductor laser 1 is converted into parallel light by a collimating lens 2 and separated into a plurality of different parallel light beams by a diffraction grating 3. A plurality of different parallel light beams pass through the beam splitter 4a of the composite element 4, and are collected on a magneto-optical disk 6 as a main beam having a diameter of about 1 micron by an objective lens 5 incorporated in an objective lens driving device (not shown). At the same time as the light is emitted, a leading beam and a trailing beam are formed at predetermined intervals as sub-beams before and after the main beam on the same track as the main beam by a so-called three-beam method. The parallel light beam reflected by the beam splitter 4a of the composite device 4 enters the monitoring light receiving device 7 and is used for controlling the drive current of the semiconductor laser 1.

[0009] The reflected light from the information recording medium 6 follows the reverse path, is reflected and separated by the beam splitter 4a of the composite element 4, and enters the polarization splitting element 4b. The semiconductor laser 1 is installed so as to have a polarization direction parallel to the paper surface, and the incident light is polarized by the polarization separation element 4b.
The light is rotated by 5 degrees and is separated into two different light beams having two orthogonally polarized light components and two mutually orthogonally polarized light components, and is reflected by the reflection mirror 4c.

The reflected light transmitted through the composite element 4 is incident on a substantially cylindrical convex lens 8 to be converged light, and is incident on a substantially cylindrical concave cylindrical lens 9. Here, the concave cylindrical lens 9 is provided so as to have a lens effect at an angle of approximately 45 degrees with respect to the image of the recording track of the information recording medium 6 existing in the direction of W1 in a plane parallel to the paper surface. .

The light transmitted through the concave cylindrical lens 9 generates astigmatism which is a part of the focus error signal detecting means. Within the surface of the concave cylindrical lens 9 having no lens surface, the light path becomes a solid line and converges on the focal point 12,
In the plane having the lens effect, the light path is indicated by a broken line and converges on the focal point 13.

The concave cylindrical lens 9 is rotated and adjusted so that the direction W2 of the concave cylindrical lens 9 having the lens effect becomes approximately 45 degrees with respect to the holding member 10, and the convex lens 8 and the concave cylindrical lens 9 are Thus, the distance is fixed at a predetermined distance in the optical axis direction.

Further, by fixing the bottom surface of the holding member 10 to the reference surface of the optical housing, positioning in the direction of astigmatism and the optical axis direction is performed.

The multi-segmented photodetector 11 has a light receiving surface located substantially in the middle between the focal points 12 and 13, and calculates the sum of the diagonals of the electric signals generated in the central four-segment light receiving area 19;
By subtracting them by the subtractor 23, a focus error signal is detected by a so-called astigmatism method. Also, of the so-called push-pull signal obtained by subtracting the sum signal of each of the upper and lower light receiving areas, only a signal of about 22 KHz is extracted by a band-pass filter (hereinafter referred to as BPF), so that the wobble signal of the information recording medium 6 is called an Adip
A signal can be detected, and the rotation speed of a spindle motor (not shown) is controlled by a spindle motor control device (not shown) based on the Adip signal.

By taking the difference between the light spot 17 of the preceding beam and the light spot 18 of the following beam, a tracking error detection signal by the so-called three-beam method is detected.

By taking the difference between the main beam 14 composed of P-polarized light and the main beam 15 composed of S-polarized light, it is possible to detect a magneto-optical disk information signal by a differential detection method. Furthermore, the pre-pit signal can be detected by taking the sum of them.

[0017]

However, in the above-described conventional configuration, the optical defocus adjustment position of the optical head alone is largely shifted in the direction in which the shape of the light spot on the information recording medium deteriorates the Adip signal. When the focus servo and the tracking servo are operated in the state, the detection capability of the Adip signal is deteriorated and the Adip signal is detected.
There has been a problem that the signal amplitude becomes small, the Adip error increases, the control of the spindle motor becomes unstable, and servo adjustment such as focus offset adjustment becomes impossible.

In view of the above-mentioned problems of the conventional optical head, the present invention forcibly applies a focus offset in advance in a direction in which the amplitude of the Adip signal increases, and adjusts the focus of the optical head. By providing focus adjustment after changing the shape of a light spot on a medium, the amplitude of the dip signal is stabilized, a good spindle servo can be realized, and a disk recording / reproducing apparatus excellent in mass productivity is provided. It is intended for.

[0019]

SUMMARY OF THE INVENTION The present invention provides an optical head mounted with an objective lens driving device having an objective lens, a focus error calculating means for calculating an optimum focus point based on a focus error signal from the optical head,
A focus error applying means for injecting a control signal into the objective lens driving device in accordance with the output signal of the focus error calculating means. When adjusting the focus of the optical head, the focus error applying means previously sets the position of the objective lens in the focus direction. Is a disk recording / reproducing apparatus for adjusting the focus of the optical head after changing the value of.

With this configuration, for example, when adjusting the defocus of the optical head incorporated in the recording / reproducing apparatus,
Even in a state where the optical focus adjustment position of the optical head alone is largely displaced in the direction in which the light spot shape on the information recording medium deteriorates the Adip signal, the focus error applying means changes the focus direction position of the objective lens to Ad.
By offsetting in advance in the direction in which the ip signal amplitude increases, stable spindle servo can be performed,
Since the detailed servo adjustment can be performed, the adjustment time and the adjustment process can be significantly reduced, and a disk recording / reproducing apparatus excellent in mass productivity can be realized.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings showing an embodiment. (First Embodiment) FIG. 1 is a schematic diagram of an optical head in a disk recording / reproducing apparatus according to a first embodiment of the present invention, and FIG. 2 is a schematic diagram of a photodetector thereof.
FIG. 3 is an exploded perspective view of the optical head according to the present embodiment, and FIG. 4 is a configuration diagram of a disk recording / reproducing apparatus.

In FIG. 1, reference numeral 1 denotes a semiconductor laser, 2 denotes a collimating lens, 3 denotes a diffraction grating, 4 denotes a composite element composed of a beam splitter 4a, a polarization splitting element 4b, and a folding mirror 4c. Is an information recording medium having a wobble signal while having a magneto-optical effect,
7 is a light receiving element for monitoring, 8 is a convex lens, 9 is a concave cylindrical lens, 10 is a holding member, 11 is a multi-segment photodetector, 12 and 13 are focal points of light spots, and 14 is formed on the multi-segment photodetector 11 Main beam (P-polarized),
Reference numeral 15 denotes a main beam (S-polarized) formed on the multi-segmented photodetector 11, 16 denotes a main beam (P + S-polarized) formed on the multi-segmented photodetector 11, and 17 denotes a light spot of the sub-beam by the preceding beam. , 18 are light spots by the following beam among the sub beams.

FIG. 2 is a diagram showing each light receiving area of the multi-segmented photodetector 11 shown in FIG.
0 is a preceding beam receiving area, 21 is a following beam receiving area,
22a and 22b are information signal receiving areas, 23 is a subtractor, 2
4 is an adder.

FIG. 3 is a view for explaining the structure of the optical head. Reference numeral 25 denotes an optical housing, and reference numeral 26 denotes an objective lens driving device.

FIG. 4 is a block diagram including a control system for the optical head and the spindle motor. Reference numeral 27 denotes a spindle motor control device, reference numeral 28 denotes a spindle motor, and reference numeral 29 denotes a focus error signal from a photodetector of the optical head. On the basis of,
A focus error calculation device 30 for calculating an optimum focus point is a focus error application device that outputs a DC signal, which is a control signal, to the optical head according to an output signal of the focus error calculation device 29.

The operation of the first embodiment configured as described above will be described below.

The light emitted from the semiconductor laser 1 is converted into parallel light by a collimating lens 2 and separated into a plurality of different parallel light beams by a diffraction grating 3. The plurality of different parallel light beams pass through the beam splitter 4a of the composite element 4 and are focused on the magneto-optical disk 6 as a main beam having a diameter of about 1 micron by the objective lens 5 incorporated in the objective lens driving device 26. At the same time, a leading beam and a trailing beam are formed at predetermined intervals as sub-beams before and after the main beam on the same track as the main beam by a so-called three-beam method. The parallel light beam reflected by the beam splitter 4a of the composite device 4 is
And is used for controlling the drive current of the semiconductor laser 1.

The reflected light from the information recording medium 6 follows the reverse path, is reflected and separated by the beam splitter 4a of the composite element 4, and enters the polarization splitting element 4b. The semiconductor laser 1 is installed so as to have a polarization direction parallel to the paper surface, and the incident light is polarized by the polarization separation element 4b.
The light is rotated by 5 degrees and is separated into two different light beams having two orthogonally polarized light components and two mutually orthogonally polarized light components, and is reflected by the reflection mirror 4c.

The reflected light transmitted through the composite element 4 is incident on a substantially cylindrical convex lens 8 to be converged light, and is incident on a substantially cylindrical concave cylindrical lens 9. Here, the concave cylindrical lens 9 is provided so as to have a lens effect at an angle of approximately 45 degrees with respect to the image of the recording track of the information recording medium 6 existing in the direction of W1 in a plane parallel to the paper surface. .

The light transmitted through the concave cylindrical lens 9 generates astigmatism which is a part of the focus error signal detecting means. Within the surface of the concave cylindrical lens 9 having no lens surface, the light path becomes a solid line and converges on the focal point 12,
In the plane having the lens effect, the light path is indicated by a broken line and converges on the focal point 13.

The concave cylindrical lens 9 is rotated and adjusted so that the direction W2 having the lens effect of the concave cylindrical lens 9 is approximately 45 degrees with respect to the holding member 10, and the convex lens 8 and the concave cylindrical lens 9 are Thus, the distance is fixed at a predetermined distance in the optical axis direction.

Further, by fixing the bottom surface of the holding member 10 to the reference surface of the optical housing, positioning in the direction of astigmatism and the optical axis direction is performed.

The multi-segmented photodetector 11 has a light receiving surface located substantially halfway between the focal points 12 and 13, and calculates the sum of the diagonals of the electric signals generated in the central four-segment light receiving area 19,
By subtracting them by the subtractor 23, a focus error signal is detected by a so-called astigmatism method. Further, by extracting only a signal of about 22 KHz by the BPF from the so-called push-pull signal obtained by subtracting the sum signal of each of the upper and lower light receiving regions, it is possible to detect the wobble signal of the information recording medium 6, the so-called Adip signal. The rotation speed of the spindle motor 28 is controlled by the spindle motor controller 27 based on the Adip signal.

By taking the difference between the light spot 17 of the preceding beam and the light spot 18 of the following beam, a tracking error detection signal by the so-called three-beam method is detected.

Further, by taking the difference between the main beam 14 composed of P-polarized light and the main beam 15 composed of S-polarized light, it is possible to detect a magneto-optical disk information signal by a differential detection method. Furthermore, the pre-pit signal can be detected by taking the sum of them.

Further, when the focus of the optical head is adjusted in a state where the optical head is incorporated in the disk recording / reproducing apparatus, the optical focus adjustment position of the optical head alone is determined by the direction in which the shape of the light spot on the information recording medium deteriorates the Adip signal. Even in the case of a large deviation, the focus error calculation device 29 calculates the optimal focus point, applies a voltage corresponding to the calculation result to the objective lens driving device 26 by the focus error application device 30, and By offsetting the focus position in the direction in which the amplitude of the Adi signal increases, stable spindle servo can be performed, and detailed adjustment such as focus adjustment and gain adjustment of the disk recording / reproducing apparatus can be performed. Here, the focus adjustment in the optical head may be performed at a position where the jitter of the frequency signal from the wobble of the information recording medium 6 is substantially minimized. Further, the focus direction position of the objective lens by the focus error applying device 30 may be set to one of a direction away from the information recording medium or a direction approaching the information recording medium.

As described above, according to the first embodiment, at the time of defocus adjustment of the optical head, the focus offset is forcibly applied in the direction in which the amplitude of the Adip signal increases, and the light on the disk is adjusted. By changing the shape of the spot, it is possible to provide an optical head in which the Adip signal is stabilized, thereby realizing a stable spindle servo and realizing a disk playing device excellent in mass productivity.

In the first embodiment, the focus offset is applied in the direction in which the amplitude of the Adip signal is increased during the focus adjustment. However, the present invention is not limited to this. At regular times, a method of increasing the light amount of the semiconductor laser 1 may be adopted. (Second Embodiment) Next, a second embodiment will be described with reference to the drawings.

The difference between this embodiment and the first embodiment is that, as shown in FIG.
The rotation speed control of the spindle motor 28 by the spindle motor control device 27 is performed without using the Adip signal, and in that state, servo adjustment such as focus adjustment and gain adjustment of the optical head is performed. After the servo adjustment, the rotation speed control of the spindle motor 28 is performed. Is performed using the Adip signal. That is, at the time of focus adjustment, a spindle motor control device 3 different from the spindle motor control device 27 is used.
1 to control the rotation speed of the spindle motor 28,
After the servo adjustment, the control is switched to the spindle motor control device 27 to control the rotation speed of the spindle motor 28.

As described above, according to the second embodiment, the rotation speed control of the spindle motor before the focus adjustment of the optical head is performed without using the Adip signal, so that the rotation speed control of the spindle motor becomes optical. Since it is not influenced by the focus adjustment accuracy of the head alone, the adjustment time and the adjustment process can be further shortened, and a disk recording / reproducing apparatus with lower cost can be provided. Third Embodiment Next, a third embodiment will be described with reference to the drawings.

The difference between this embodiment and the above-described first embodiment is that, as shown in FIG. 5, the information recording medium has a pit portion substantially equivalent to that of a compact disc and an Adip signal. At the time of focus adjustment, the spindle motor 28 is first constructed at the pit section.
Preliminary focus adjustment is performed while controlling the rotation speed of the spindle motor control device 31 that does not use the Dip signal. When the focus adjustment of the magneto-optical unit is performed next, the focus adjustment of the pit unit is performed in advance. After applying the focus offset that becomes the preliminary adjustment position
That is, the servo adjustment such as the focus adjustment and the gain adjustment of the optical head is performed while the rotation speed of the spindle motor 28 is controlled by the spindle motor control circuit 27 using the Adip signal. FIG. 6 shows a conceptual diagram of the adjustment method at this time.

As described above, according to the third embodiment, in an information recording medium having a plurality of standards, preliminary adjustment of the focus of the optical head is performed in advance by a method that does not use an Adip signal. By performing the focus adjustment of the information recording medium portion having the Adip signal using the value as a provisional set value, the rotation speed control of the spindle motor is not affected by the focus adjustment accuracy of the optical head alone, so that the adjustment time is further increased. , And the adjustment process can be shortened, so that a lower-cost optical head and disk recording / reproducing apparatus can be provided.

In the third embodiment, the information recording medium has a single structure composed of a pit portion and a magneto-optical portion. However, the present invention is not limited to this. It is good also as a plurality of pieces consisting of. Further, a single or plural sheets having different recording densities or a single or plural sheets having different substrate thicknesses may be used.

[0044]

As is apparent from the above description, according to the present invention, the focus adjustment of the optical head is performed after the focus direction position of the objective lens is changed in advance by the focus error applying means during the focus adjustment of the optical head. Therefore, good spindle servo can be realized and mass productivity is excellent.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of an optical head in a disk recording and reproducing apparatus according to a first embodiment of the present invention.

FIG. 2 is a schematic diagram of a photodetector according to the first embodiment.

FIG. 3 is an exploded perspective view of the optical head according to the first embodiment.

FIG. 4 is a configuration diagram of a disk recording / reproducing apparatus according to the first embodiment.

FIG. 5 is a configuration diagram of an optical head according to second and third embodiments of the present invention.

FIG. 6 is a conceptual diagram of an adjustment method according to a third embodiment of the present invention.

FIG. 7 is a schematic view of a conventional optical head.

FIG. 8 is a schematic view of a photodetector of a conventional optical head.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Semiconductor laser 2 Collimating lens 3 Diffraction grating 4 Composite element 5 Objective lens 6 Information recording medium 8 Convex lens 9 Concave cylindrical lens 11 Multi-split photodetector 12, 13 Focus of light spot 19 4-split light receiving area 20 Preceding beam receiving area 21 After Row beam receiving area 22a, 22b Information signal receiving area 23 Subtractor 24 Adder 25 Optical housing 26 Objective lens driving device 27, 31 Spindle motor control device 28 Spindle motor 29 Focus error calculating device 30 Focus error applying device

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kouji Okamura 1006 Kazuma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (10)

[Claims] An optical head mounted with an objective lens driving device having an objective lens; a focus error calculating means for calculating an optimum focus point based on a focus error signal from the optical head; and an output of the focus error calculating means. A focus error applying unit that injects a control signal into the objective lens driving device in accordance with a signal, wherein the focus error applying unit changes the focus direction position of the objective lens in advance when adjusting the focus of the optical head. And a focus adjustment of the optical head after the recording. 2. An optical head mounted with an objective lens driving device having an objective lens, a focus error calculating means for calculating an optimum focus point based on a focus error signal from the optical head, and an output of the focus error calculating means. A focus error applying unit for injecting a control signal into the objective lens driving device in response to a signal; a tracking servo control unit; and a spindle motor control unit, wherein the focus control of the optical head is performed during the tracking servo operation by the tracking control unit. When adjusting,
A disk recording / reproducing apparatus, wherein the focus adjustment of the optical head is performed only after the focus error applying unit changes the focus direction position of the objective lens only when the spindle motor control unit is inoperable. 3. The disk recording apparatus according to claim 1, wherein the focus error position of the objective lens is set to one of a direction moving away from the information recording medium and a direction approaching the information recording medium by the focus error applying means. Playback device. 4. The disk recording / reproducing apparatus according to claim 3, wherein the spindle motor control means controls the number of revolutions based on a frequency signal from a wobble of the information recording medium. 5. A semiconductor laser as a light source, a tracking servo control means, and a spindle motor control means, wherein said spindle motor control means controls the focus of said optical head during tracking servo operation by said tracking control means. 2. The disk recording / reproducing apparatus according to claim 1, wherein the light amount of the semiconductor laser is changed only when the means cannot operate. 6. The disk recording / reproducing apparatus according to claim 5, wherein the change in the light amount of the semiconductor laser is an increase. 7. A spindle motor comprising: a spindle motor for rotating an information recording medium; and spindle motor control means for controlling the number of revolutions of the spindle motor based on a frequency signal from a wobble of the information recording medium. Motor control means, when adjusting the focus of the optical head,
2. The disk recording / reproducing apparatus according to claim 1, wherein the rotation speed of the spindle motor is controlled without using a frequency signal from a wobble of the information recording medium. 8. The disk recording / reproducing apparatus according to claim 1, wherein the focus adjustment of the optical head is performed at a position where the jitter of the frequency signal from the wobble of the information recording medium is substantially minimized. 9. An optical head mounted with an objective lens driving device having an objective lens, a focus error calculating means for calculating an optimum focus point based on a focus error signal from the optical head, and an output of the focus error calculating means. A focus error applying means for injecting a control signal into the objective lens driving device in accordance with a signal, wherein a plurality of information recording media having a plurality of different standards are recorded and reproduced, and At the time of head focus adjustment, after the focus adjustment of the optical head is performed in a predetermined standard area of the information recording medium in advance, the focus error applying means uses the focus adjustment value to set the focus direction of the objective lens. After changing the position, the focus adjustment of the area of another standard of the information recording medium is performed. A disk recording / reproducing apparatus characterized by performing the following. 10. The disk recording / reproducing apparatus according to claim 9, wherein the information recording medium has a single configuration composed of a plurality of different standards.