JP2003036557A - Optical pickup device and optical information recording/ reproducing apparatus using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a miniaturized and low-price optical pickup device which can detect a servo signal well and can record, for a plurality of kinds of optical disks whose disk guide groove pitches are different. SOLUTION: The optical pickup device is used, in which five laser beams are concentrated on the optical disk using a grating 2a, and which selects the laser beam to be used for detecting the servo signal in accordance with the kind of the optical disk to be reproduced or recorded. A first, a second, a third, a fourth, and a fifth acceptance regions are provided at respective positions to which the five beams reflected by the optical disk are concentrated in a photodetector 9a, in which an acceptance surface which is divided into four like a cross-in-square shape is provided in at least one acceptance region.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for recording or reproducing information on an optical disc.

[0002]

2. Description of the Related Art Optical disks are information storage media characterized by non-contact, large capacity, high speed access, and low cost.
Utilizing these characteristics, it is widely used as a reproducing medium for digital audio signals or as a package medium for computer software.
Furthermore, in recent years, not only read-only optical discs but also many writable optical discs are on the market.

Among them, the CD-R disc, which is a writable optical disc, has a recording capacity of 400 times or more that of a magnetic floppy disc (FD), but its market price is almost the same as that of the FD, and therefore it is rapidly spreading. .
In addition, the need for moving images has become large and diversified due to the improvement of digital moving image processing capability. For recording large-capacity digital information such as moving images, a DVD-R having a storage capacity about 7 times that of a CD-R. Disc, DVD-R
High density optical discs such as W discs and DVD-RAM discs are receiving attention.

Under such a background, for example, Japanese Patent Laid-Open No. 2000-
No. 082226 discloses a technique for recording / reproducing a DVD-RAM disc or a CD-R / RW disc with a single optical pickup device by using a 12-division light receiving surface.

[0005]

On the other hand, the substrate thickness of DVD-R discs, DVD-RW discs and DVD-RAM discs is 0.6 mm, and the wavelength of laser light used for recording or reproduction is common to the 650 nm band. But
At present, the physical formats of optical disks are different. For example, an information recording surface of a writable optical disc is provided with a continuous guide groove in advance, and an information signal is recorded or erased along the guide groove. The disc guide groove pitch is a DVD-R disc or DVD
-While 0.74 μm for RW disc, DV
1.48 μm or 1.
It is 23 μm.

Thus, even though the thickness of the disk substrate and the wavelength of the laser used for recording are the same, the pitches of the disk guide grooves are different, so that a single optical pickup device can be used for a DVD-R.
It has heretofore been difficult to detect a servo signal favorably and perform recording on a disc or a DVD-RAM disc.

However, as an optical pickup device for recording or reproducing information, it is desirable that the same device is capable of recording or reproducing different types of optical disks together, and is small in size and low in price.

The present invention provides a small-sized and low-priced optical pickup device capable of satisfactorily detecting servo signals for recording on a plurality of types of optical discs having different disc guide groove pitches.

[0009]

In order to solve the above problems, in the present invention, at least one semiconductor laser light source and at least one light beam emitted from the semiconductor laser light sources are provided. An optical branching element for branching into five light beams, a focusing optical system for focusing the five light beams and irradiating five light spots on the optical information recording medium, and the optical information recording medium And an optical detector that receives the five light beams reflected by the optical pickup device.

Further, the irradiation position of the five light spots on the optical information recording medium is different in the radial direction of the optical information recording medium.

Further, the photodetector has first, second, third, fourth and fifth light receiving regions at respective positions irradiated by the five light beams reflected by the optical information recording medium. An optical pickup device characterized by being provided is used.

Further, among the first, second, third, fourth and fifth light receiving regions, at least one light receiving region is provided with a light receiving surface divided into four in a square shape. An optical pickup device is used.

The light branching element is a linear diffraction grating having a rectangular linear grating groove pattern, and the five light beams are 0 out of the light beams diffracted and separated by the linear diffraction grating. Next light, + 1st light, -1st light, +
An optical pickup device is used which is secondary light and −secondary light.

[0014]

1 is a schematic diagram showing a first embodiment of an optical pickup device according to the present invention.

In FIG. 1, the laser light source 1a is, for example, 6
It is a semiconductor laser that oscillates at a wavelength of 50 nm band. The light beam emitted from the laser light source 1a is diffracted and separated by the diffraction grating 2a and reflected by the beam splitter 4a. Here, the light beam diffracted and separated by the diffraction grating 2a is zero-order light that passes through the diffraction grating 2a as it is and 0 at a predetermined diffraction angle.
It is at least five light beams of ± first-order diffracted light and ± second-order diffracted light that are separated from the next light and proceed. These five light beams are reflected by the beam splitter 4a, converted into a substantially parallel light beam by the collimator lens 5a, and then converted by the objective lens 6a into, for example, a DVD-ROM disc, a DVD-R disc, a DVD-RW disc, or a DVD-RAM. Substrate thickness such as disk 0.6m
Then, the light is focused on the recording surface of the optical disc 7 of m, and five light spots are formed on the information recording surface of the optical disc 7, as will be described later. Here, the objective lens 6a is the actuator 1
0a integrally holds the coil 11a from the outside.
It is possible to drive in the focus direction and the tracking direction by energizing.

The five light beams reflected by the optical disk 7 follow the same optical path as the outward path, pass through the objective lens 6a, the collimator lens 5a and the beam splitter 4a, and then enter the detection lens 8a.

The detection lens 8a is provided with, for example, a cylindrical lens, and the direction of the astigmatism generated by the detection lens 8a is approximately 45 degrees with respect to the dividing line of the light receiving surface in the photodetector 9a described later. Is set to. The five light beams that have passed through the detection lens 8a and have astigmatism in the direction of approximately 45 degrees are condensed on a predetermined light receiving surface in the photodetector 9a.

Next, an embodiment relating to the light spot converging position on the optical disk 7 will be described with reference to FIG. In order to simplify the description, of the light beams diffracted and separated by the diffraction grating 2 a, the light spot of the 0th-order light is changed to the light spot 10.
The light spot of 0, + 1st order light is a light spot 101, the light spot of −1st order light is a light spot 102, the light spot of + secondary light is a light spot 103, and the light spot of −2nd order light is a light spot 104. .

When the diffraction angle is small, the distance between the focus positions of the 0th-order light spot 100 and the −2nd-order light spot 104 (or the + 2nd-order light spot 103) focused on the optical disk 7 in the radial direction of the disk. Tp2 is approximately twice as large as the condensing position interval Tp1 in the disk radial direction between the 0th-order light spot 100 and the -1st-order light spot 102 (or the + 1st-order light spot 101).

In this embodiment, Tp1 is, for example, DVD
Since it is set to about 0.37 μm, which is half the guide groove pitch of the −R disc and the DVD-RW disc,
As shown in (a), a DVD-R disc or a DVD-RW
When the light spot 100 of 0th-order light is located directly on the guide groove 300 of the disk on the disc, the light spot 101 of the + 1st-order diffracted light and the light spot 102 of the -1st-order diffracted light are respectively between adjacent guide grooves. Located right above.

Since Tp2 is approximately twice as large as Tp1, its value is approximately 0.74 μm, which is half the guide groove pitch in a 2.6 GB DVD-RAM disc on one side, and as shown in FIG. 2B, for example. One side 2.6GB DVD-R
On the AM disk, +2 when the 0th-order light spot 100 is located directly above the guide groove 301 of the disk.
The light spot 103 of the second-order diffracted light and the light spot 104 of the −second-order diffracted light are located directly above the adjacent guide grooves.

In the present invention, Tp1 is not limited to the above value, and what value is Tp1 as long as the servo signal can be detected by using the light receiving surface pattern described later and the servo signal detection method described later. But it doesn't matter. For example, when Tp1 is set to approximately 0.34 μm,
The value of Tp1 is about 10% with respect to about 0.37 μm which is half the guide groove pitch of a DVD-R disc or a DVD-RW disc. The value of Tp2 is approximately 0.
68 μm, which is a 2.6-GB DVD-RA on one side.
Approximately 0.7, which is half the guide groove pitch in the M disc
The deviation amount is about 10% with respect to about 0.615 μm, which is a half of the guide groove pitch in a DVD-RAM disc of 4 μm and 4.7 GB on one side. However, by using the light receiving surface pattern described later and the servo signal detection method described later, a DVD-R disc, DV
Servo signals can be detected from the D-RW disc and the DVD-RAM disc.

Next, a first embodiment of the light receiving surface pattern in the photodetector 9a and the light spot condensing position on the light receiving surface in the present invention will be described with reference to FIG.

In the photodetector 9a, for example, as shown in FIG. 3, four divided light receiving areas 200 each having a divided light receiving surface represented by symbols a1, b1, c1, d1 are arranged. , A two-divided light receiving area 201 represented by symbols e1 and f1 and two-divided light receiving area 202 represented by symbols i1 and j1 and two-divided light receiving surfaces represented by symbols m1 and n1. A region 203 and a two-divided light receiving region 204 represented by symbols q1 and r1 are arranged. Then, on the light receiving region 200, the light spot 10 on the disc
The disk reflected light of 0 is condensed to form a detection light spot 110. Similarly, the disc reflected light of the disc light spot 101 on the light receiving area 201, the disc reflected light of the disc light spot 102 on the light receiving area 202, the disc reflected light of the disc light spot 103 on the light receiving area 203, On the light receiving area 204, the disc reflected lights of the on-disc light spot 104 are respectively condensed to form detection light spots 111, 112, 113 and 114.

Further, each detection signal photoelectrically converted and detected on each of the light receiving surfaces a1, b1, c1, d1 is sent to the output terminal of the photodetector 9a. Here, in order to reduce the number of output terminals, for example, the light-receiving surface e1 is the light-receiving surface i1 and the photodetector 9
The light receiving surface f1 is similarly connected inside the light receiving surface j1
, The light receiving surface m1 is the light receiving surface q1, and the light receiving surface n1 is the light receiving surface r.
It does not matter whether it is internally connected to 1 or not, and each detection signal photoelectrically converted and detected is sent to the output terminal of the photodetector 9a. Hereinafter, for simplification of description, these detection signals are denoted by the same symbols as the light receiving surface on which the detection signals are detected. After all, from the photodetector 9a, for example, at least eight output terminals a1, b1, c1,
d1, e1 + i1, f1 + j1, m1 + q1, n1 + r
1 will be output.

Here, as a tracking error signal detection method, in the case of recording on a DVD-R disc or a DVD-RW disc, for example, the output signal a of the light receiving area 200 is used.
Main spot 11 obtained from 1, b1, c1, d1
0 push-pull signal (a1 + d1)-(b1 + c1)
And the output signals e of the light receiving areas 201 and 202
Sub-spot 11 obtained from 1 + i1, f1 + j1
Push-pull signals (e1 + i1)-(f1
+ J1) is subtracted, and the differential push-pull method (hereinafter referred to as D for simplification), which is already known tracking servo technology.
This is called the PP method. ). Also DVD-RA
When recording or reproducing on the M disc, for example, the push-pull signal of the main spot 110 obtained from the output signals a1, b1, c1, d1 of the light receiving area 200 and the output signals m1 + q1, of the light receiving areas 203 and 204.
The push-pull signals of the sub-spots 113 and 114 obtained from n1 + r1 are detected by the subtractive DPP method. Further, when reproducing a read-only disc having phase pits corresponding to a recording signal, such as a DVD-ROM disc, or a written DVD-R disc or DVD-RW disc, the light receiving area 2
The output signals a1, b1, c1 and d1 from 00 are used for the phase difference detection method. Since the phase difference detection method is a known technique, detailed description thereof will be omitted.

As a method of detecting the focus error signal, when recording on a DVD-R disc or a DVD-RW disc and recording or reproducing on a DVD-RAM disc, for example, the output signal a1 of the light receiving area 200 is used.
Detection is performed using the signal (a1 + c1)-(b1 + d1) by the astigmatism method obtained from b1, c1, and d1. Also, a DVD-ROM disc and a written DV
Also when reproducing a D-R disc or a DVD-RW disc, the output signals a1, b1, c1, d1 of the light receiving area 200 are reproduced.
Signal (a1 + c1) -by the astigmatism method obtained from
Detection is performed using (b1 + d1). Since the astigmatism method is a known technique, detailed description thereof will be omitted.

By the way, in the case of an optical disc having a guide groove, if a focus error signal is detected from the reflected light beam from the optical disc by the astigmatism method, it is disclosed in Japanese Patent Laid-Open No.
As described in detail in No. 00-082226, there is a problem that a large disturbance easily occurs in the detected focus error signal. Therefore, for the purpose of canceling the disturbance, the light receiving surface pattern in the photodetector 9a may be a pattern as shown in FIG.

FIG. 4 shows a second embodiment of the light receiving surface pattern in the photodetector 9a and the light spot condensing position on the light receiving surface in the present invention. 3, the light receiving areas 203 and 204 are designated by the symbols m1, n1, o1, p1 and the symbol q.
It has a configuration in which it is replaced with a four-divided light receiving area represented by 1, r1, s1, and t1. Therefore, when recording or reproducing on a DVD-RAM disc, the signal (a1 + c1)-(b1 + d1) by the astigmatism method obtained from the output signals a1, b1, c1, d1 of the light receiving area 200 and the light receiving surface areas 203 and 204. Output signal m1 + q1, n1
Signal (m1 + q1 + o1 + s1)-(n1 +) obtained by + r1, o1 + s1, p1 + t1 by the astigmatism method.
r1 + p1 + t1), that is, an astigmatism method having a function of canceling the above-mentioned disturbance (details are disclosed in Japanese Patent Application Laid-Open No. 2000-082226, and thus omitted. It is possible to detect the focus error signal by the point aberration method. A tracking error detection method using the light receiving surface pattern shown in FIG. 4, recording on a DVD-R disc or a DVD-RW disc, a DVD-ROM disc, or a written DVD-R disc
The focus error detection method when reproducing a disc or a DVD-RW disc is the same as when the light receiving surface pattern shown in FIG.

Further, the light receiving surface pattern in the photodetector 9a may be a pattern as shown in FIG. FIG. 5 shows a third embodiment relating to the light receiving surface pattern in the photodetector 9a and the light spot condensing position on the light receiving surface in the present invention. Figure 4
With respect to the light receiving regions 201 and 202,
1, g1, h1 and the symbols i1, j1, k1, l1 are replaced by the four-divided light receiving regions.
Therefore, the output signals a1, b1, c from the light receiving area 200
1, d1 and the output signals e1 + i1, f1 + j1, g1 + k1, h1 + l1 from the light-receiving surface areas 201 and 202, the DVD-R disc and the DVD-R are used.
Even when recording on a W disc, the focus error signal can be detected by the differential astigmatism method. A tracking error detection method using the light receiving surface pattern shown in FIG. 5, a case of recording or reproducing on a DVD-RAM disk, a DVD-ROM disk, or a written DVD-R disk or DVD
Since the focus error detection method in reproducing the RW disc is the same as that in the case of using the light receiving surface pattern shown in FIG. 4, description thereof will be omitted. Further, regarding the signal processing in the above-mentioned detection method, Japanese Patent Laid-Open No. 2000-
Since it has been described in detail in Japanese Patent Application No. 082226 and Japanese Patent Application No. 2000-371484, its description is omitted.

FIG. 6 is a schematic diagram showing a second embodiment of the optical pickup device according to the present invention.

In FIG. 6, the laser light source 1b is, for example, 7
It is a semiconductor laser that oscillates at a wavelength in the 80 nm band. The light beam emitted from the laser light source 1b is diffracted and separated by the diffraction grating 2b and reflected by the beam splitter 4b. Here, the light beam diffracted and separated by the diffraction grating 2b is, similarly to the above, the 0th-order light that passes through the diffraction grating 2b as it is, and the ± 1st-order diffracted light and the ± 2nd-order diffracted light that separate and proceed from the 0th-order light at a predetermined diffraction angle. , At least five light beams.
These five light beams are reflected by the beam splitter 4b, converted into a substantially parallel light beam by the collimator lens 5b, and then, for example, a CD-ROM by the objective lens 6b.
Disc or CD-R Disc or CD-RW
A disc or the like is focused on the recording surface of an optical disc 14 having a substrate thickness of 1.2 mm, and the optical disc 1 will be described later.
Five light spots are formed on the No. 4 information recording surface. Here, the objective lens 6b is integrally held by the actuator 10b and can be driven in the focus direction and the tracking direction by energizing the coil 11b from the outside.

The five light beams reflected from the optical disk 14 follow the same optical path as the outward path in the reverse direction, and the objective lens 6b,
After passing through the collimator lens 5b and the beam splitter 4b, the light enters the detection lens 8b.

The detection lens 8b is provided with, for example, a cylindrical lens, and the direction of the astigmatism generated by the detection lens 8b is approximately 45 degrees with respect to the dividing line of the light receiving surface in the photodetector 9b which will be described later. Is set to. Five light beams that have passed through the detection lens 8b and have astigmatism in the direction of approximately 45 degrees are condensed on a predetermined light receiving surface in the photodetector 9b.

Next, a first embodiment relating to the light spot converging position on the optical disk 14 will be described with reference to FIG. To simplify the description, of the light beams diffracted and separated by the diffraction grating 2b, the 0th-order light spot is the light spot 120 and the + 1st-order light spot is the light spot 12.
The light spot of the 1st- and -1st-order lights is a light spot 122, the light spot of the + 2nd-order light is a light spot 123, and the light spot of the -2nd-order light is a light spot 124.

When the diffraction angle is small, the condensing positions of the 0th-order light spot 120 and the −2nd-order light spot 124 (or the + 2nd-order light spot 123) condensed on the optical disk 14 in the radial direction of the disk. The interval Tp4 is the same as the above description, that is, the 0th-order light spot 120 and the -1st-order light spot 122 (or the + 1st-order light spot 12).
It is approximately twice the light collection position interval Tp3 in the disk radial direction of 1).

In this embodiment, Tp3 is, for example, CD-
Since the information track pitch is set to about 0.4 μm, which is a quarter of the information track pitch of the ROM disk, as shown in FIG. When located directly above the column 500, the light spot 123 of the + 2nd-order diffracted light and the light spot 124 of the −2nd-order diffracted light are located directly between the adjacent information track columns.

Since Tp4 is approximately twice as large as Tp3, its value is approximately 0.8 μm which is half the pitch of the guide grooves in a CD-R disc or a CD-RW disc.
On the CD-R disc or the CD-RW disc as shown in (b), when the light spot 120 of the 0th-order light is located directly above the guide groove 302 of the disc, the light spots 123 of the + 2nd-order diffracted light and − Light spot 1 of 2nd order diffracted light
24 are located directly above the adjacent guide grooves.

Next, a first embodiment relating to the light receiving surface pattern in the photodetector 9b and the light spot condensing position on the light receiving surface in the present invention will be described with reference to FIG.

In the photodetector 9b, for example, as shown in FIG. 8, there are arranged light receiving areas 210 each of which has a divided light receiving surface divided into four in a square shape represented by symbols a2, b2, c2 and d2.
The light receiving regions 211, i represented by the symbol e2 on both sides thereof are shown.
2, a light receiving area 212 represented by 2, a two-divided light receiving area 213 represented by symbols m2 and n2, and symbols q2 and r.
A two-divided light receiving area 214 indicated by 2 is arranged. Then, on the light receiving area 210, the disc reflected light of the on-disc light spot 120 is condensed, and the detection light spot 1
Forming 30. Similarly, on the light receiving area 211, the disk reflected light of the light spot 121 on the disk, the light receiving area 2
12, the reflected light of the disc light spot 122 is on the disc 12, and the light spot 123 is on the disc light spot 123.
On the disc reflected light and the light receiving region 214, the disc reflected light of the on-disc light spot 124 is condensed respectively to form detection light spots 131, 132, 133 and 134.

The detection signals photoelectrically converted and detected by the light receiving surfaces a2, b2, c2, d2 are sent to the output terminals of the photodetector 9b. Here, in order to reduce the number of output terminals, for example, the light receiving surface m2 is the light receiving surface q2 and the light receiving surface n is
It does not matter whether 2 is connected to the light receiving surface r2 and the inside of the photodetector 9b, and each detection signal photoelectrically converted and detected is sent to the output terminal of the photodetector 9b. Hereinafter, for simplification of description, these detection signals are denoted by the same symbols as the light receiving surface on which the detection signals are detected. After all, from the photodetector 9b, for example, at least eight output terminals a2, b2, c2, d2, e2, i2, m are output.
2 + q2, n2 + r2 will be output.

Here, as a method of detecting the tracking error signal, when recording on a CD-R disc or a CD-RW disc, for example, the output signal a from the light receiving area 210 is used.
2, b2, c2, d2 and the output signals m2 + q2, n2 + r2 from the light receiving area 213 and the light receiving area 214 are used for detection by the DPP method. Also CD-RO
When reproducing an M disc or a written CD-R disc or a CD-RW disc, the light receiving area 211
And the output signals e2 and i2 from the light receiving area 212 are detected by the three-spot method (the three-spot method is a well-known technique, so detailed description is omitted).

As a method of detecting the focus error signal, when recording on a CD-R disc or a CD-RW disc, for example, output signals a2 and b from the light receiving area 210 are used.
2, c2, d2 are used to detect by the astigmatism method. Also, when reproducing a CD-ROM disc or a written CD-R disc or CD-RW disc, the output signals a2, b2, c2, d2 from the light receiving region 210 are used to detect by the astigmatism method. .

On the other hand, when the focus error signal is detected from the optical disc having the guide groove by the astigmatism method, there is a problem that a large disturbance is likely to occur in the detected focus error signal as described above. Therefore, in order to cancel the disturbance, the light receiving surface pattern in the photodetector 9b may be a pattern as shown in FIG.

FIG. 9 shows a second embodiment relating to the light receiving surface pattern in the photodetector 9b and the light spot condensing position on the light receiving surface in the present invention. 8, the light receiving areas 213 and 214 are designated by the symbols m2, n2, o2, p2 and the symbol q.
It is replaced with a four-divided light receiving area represented by 2, r2, s2, and t2. Therefore, when recording on a CD-R disc or a CD-RW disc, the light receiving area 210
Output signals a2, b2, c2, d2 and the light receiving surface area 2
Output signals m2 + q2, n2 + r from 13 and 214
By using 2, o2 + s2, p2 + t2, it becomes possible to detect the focus error signal by the differential astigmatism method. It should be noted that the tracking error detection method using the light receiving surface pattern shown in FIG.
Since the focus error detection method for reproducing the M disc or the written CD-R disc or CD-RW disc is the same as the case of using the light receiving surface pattern shown in FIG. 8, description thereof will be omitted. Further, regarding the signal processing in the above-mentioned detection method, Japanese Patent Laid-Open No. 2000-0
Since it has been described in detail in No. 82226 and Japanese Patent Application No. 2000-371484, it will be omitted.

In the present invention, of the light beams diffracted and separated by the diffraction grating 2a and the diffraction grating 2b, five light beams of 0th order light, ± 1st order light and ± 2nd order light are used for servo signal detection. Therefore, the 0th-order light, the ± 1st-order light, and the ± 1st-order lights in the diffraction grating 2a and the diffraction grating 2b are included to the extent that the servo signal can be detected by the above-described servo signal detection method.
It is necessary to secure the diffracted light intensity of the secondary light.

In general, the intensity of diffracted light in a diffraction grating having a rectangular groove as shown in FIG. 10 can be expressed by equation (1). Here, the refractive index of the diffraction grating is N, the grating groove depth is D,
The grating width is W, the grating pitch is P, the wavelength of incident light is λ, and the ratio of the grating width to the grating pitch is β (= W / P).

[0048]

[Equation 1]

As is clear from the equation (1), when β = 0.5, the even-order diffracted light intensity becomes zero. Therefore, in order to secure the diffracted light intensities of the 0th order light, the ± 1st order light, and the ± 2nd order light, it is necessary to set the values of the grating groove depths D and β to appropriate values.

Then, for example, FIG. 11 is a graph showing the relationship between the grating groove depth and the diffracted light intensity when β = 0.15. By setting the grating groove depth D = 0.6λ, While maintaining a relatively high diffracted light intensity (≈67%), +
First-order light (or -1st-order light) and + second-order light (or -2)
The intensity of the diffracted light of the next light can be set to a value of approximately the same value (≈5%).

The shape of the diffraction grating in the present invention is not limited to the above, and may be any shape as long as the above-mentioned servo signal can be detected.

12 and 13 are schematic diagrams showing a third embodiment of the optical pickup device according to the present invention, showing a state where the optical disc 7 and the optical disc 14 are being reproduced or recorded.

In FIG. 12, the light beam emitted from the laser light source 1a having an oscillation wavelength of 650 nm is diffracted and separated by the diffraction grating 2a. Five light beams of 0th order light, ± 1st order diffracted light, and ± 2nd order diffracted light diffracted and separated by the diffraction grating 2a are reflected by the beam splitter 3 and then transmitted through the beam splitter 4c. The five light beams that have passed through the beam splitter 4c are converted into substantially parallel light fluxes by the collimator lens 5c, and then are condensed on the recording surface of the optical disc 7 by the objective lens 6c. As shown in FIG. Five light spots are formed on the recording surface. Note that the distance between the condensing positions in the radial direction of the disc is exactly the same as that of the above-described embodiment relating to the condensing position of the light spot on the optical disc 7, and the description thereof will be omitted.

The objective lens 6c is compatible with, for example, laser light having a wavelength of 650 nm and a wavelength of 780 nm, and can focus light on optical disks having different substrate thicknesses. The objective lens 6c is integrally held by an actuator 10c, and can be driven in the focus direction and the tracking direction by energizing the coil 11c from the outside.

The five light beams reflected from the optical disk 7 follow the same optical path as the forward path in the reverse direction, and the objective lens 6
After passing through c, the collimator lens 5c, the beam splitter 4c, and the beam splitter 3, the light enters the detection lens 8c.

The detection lens 8c is provided with, for example, a cylindrical lens, and the direction of astigmatism obtained by combining the astigmatism generated by passing through the beam splitter 3 and the astigmatism generated by the detection lens 8c will be described later. The light detector 9c is set so as to be oriented at an angle of approximately 45 degrees with respect to the dividing line of the light receiving surface. After passing through the detection lens 8c, approximately 4
Five light beams having astigmatism in the 5 degree direction are condensed on a predetermined light receiving surface in the photodetector 9c.

In FIG. 13, the oscillation wavelength is 780 nm.
The light beam emitted from the laser light source 1b in the band is the diffraction grating 20.
It is diffracted and separated by and reflected by the beam splitter 4c. The light beams diffracted and separated by the diffraction grating 20 are at least three light beams, that is, the 0th-order light that passes through the diffraction grating 20 as it is and the ± 1st-order diffracted light that separates and advances from the 0th-order light at a predetermined diffraction angle. . These three light beams are reflected by the beam splitter 4c and collimate lens 5c.
After being converted into a substantially parallel light flux by the objective lens 6c, it is condensed on the recording surface of the optical disc 14 to form three light spots on the information recording surface of the optical disc as shown in FIG.

FIG. 14 shows a second embodiment relating to the light spot condensing position on the optical disk 14. In order to simplify the description, of the light beams diffracted and separated by the diffraction grating 20, the light spot of the 0th order light is changed to the light spot 1.
The light spots of the 40th and + 1st-order lights are the light spots 141 and -1
The light spot of the next light is a light spot 142. In this embodiment, the light-converging position interval Tp5 of the light spots 140, 141, 142 of the three light beams focused on the optical disc 14 in the disc radial direction is, for example, the guide groove pitch of a CD-R disc or a CD-RW disc. It is set to about 0.8 μm, which is half. Therefore, FIG.
On a CD-ROM disc as shown in (a),
When the 0th-order light spot 140 is located directly above the disc information track row 500, the + 1st-order diffracted light spot 141 and the -1st-order diffracted light spot 142 are located directly above adjacent information track rows. Located in. As shown in FIG. 14B, a CD-R disc or a CD-R
On the RW disc, +1 when the 0th-order light spot 140 is located directly above the guide groove 302 of the disc.
The light spot 141 of the second-order diffracted light and the light spot 142 of the -1st-order diffracted light are located directly above the adjacent guide grooves.

The three light beams reflected by the optical disk 14 follow the same optical path as the outward path in the reverse direction, and the objective lens 6
After passing through c, the collimator lens 5c, the beam splitter 4c, and the beam splitter 3, the light enters the detection lens 8c.

Here, the detection lens 8c is as described above.
The direction of astigmatism, which is a combination of the astigmatism generated by passing through the beam splitter 3 and the astigmatism generated by the detection lens 8c, is approximately 45 degrees with respect to the dividing line of the light receiving surface in the photodetector 9c. It is set to be the direction.
The three light beams that have passed through the detection lens 8c and have astigmatism in the direction of approximately 45 degrees are condensed on a predetermined light receiving surface in the photodetector 9c.

By the way, the light receiving surface pattern in the photodetector 9c in the present invention may be any of the patterns shown in FIG. 3, FIG. 4 and FIG. Further, the light spot condensing positions on the light receiving surface of the five light beams reflected by the optical disk 7 are the same as those shown in FIGS. 3, 4 and 5. Therefore, when recording on a DVD-R disc or a DVD-RW disc and when recording or reproducing on a DVD-RAM disc, a DVD-ROM disc or a written DVD-R disc or DVD-RW
The servo signal in reproducing the disc is detected by using the above-described servo signal detection method, and thus detailed description thereof will be omitted.

Next, FIG. 1 shows the light spot condensing positions on the light receiving surface of the three light beams reflected by the optical disk 14.
5, and FIG. 16 and FIG. FIGS. 15, 16 and 17 show the light spot condensing positions on the light receiving surface of the three light beams reflected by the optical disc 14 in the respective light receiving surface patterns. In any of the light receiving surface patterns, the disc reflected light of the on-disc light spot 140 is condensed on the light receiving region 200 to form the detection light spot 150. Similarly, the disc reflected light of the disc light spot 141 is condensed on the light receiving region 201, and the disc reflected light of the disc light spot 142 is condensed on the light receiving region 202 to form detection light spots 151 and 152. .

When reproducing a CD-ROM disc and recording or reproducing on a CD-R disc or a CD-RW disc, the output signal a from the light receiving area 200 is used.
By using 1, b1, c1, and d1, the focus error signal is detected by the astigmatism method, and the light receiving region 200 is detected.
Output signals a1, b1, c1, d1 from the light receiving region 20
The tracking error signal is detected by the DPP method by using the output signals from 1 and the light receiving area 202. Here, if the light receiving surface pattern shown in FIG. 17 is used,
When recording on a CD-R disc or a CD-RW disc, the focus error signal can be detected by the differential astigmatism method.

Here, the light spot condensing position on the light receiving surface of the disc reflected light of the disc optical spot 141 and the disc reflected light of the disc optical spot 142 is shown in FIG.
5, and is not limited to FIG. 16 and FIG. For example, the disc reflected light of the disc light spot 141 is condensed on the light receiving region 203, and the disc reflected light of the disc light spot 142 is condensed on the light receiving region 204 to form detection light spots 151, 152. It doesn't matter. At this time, when the CD-ROM disc is reproduced and when the CD-R disc or the CD-RW disc is recorded or reproduced, the output signal a from the light receiving area 200 is used.
By using 1, b1, c1, and d1, the focus error signal is detected by the astigmatism method, and the light receiving region 200 is detected.
Output signals a1, b1, c1, d1 from the light receiving region 20
The tracking error signal is detected by the DPP method by using the output signals from 3 and the light receiving area 204. When the light receiving surface patterns shown in FIGS. 16 and 17 are used here, when recording on a CD-R disc or a CD-RW disc, the focus error signal can be detected by the differential astigmatism method.

By the way, a CD-R disc and a CD-R
When the function of recording on the W disc is not required, the light spot focusing position on the optical disc 14 is not limited to that shown in FIG. 14, and may be the light spot focusing position as shown in FIG. 18, for example.

FIG. 18 shows an optical disk 14 according to the present invention.
The 3rd example concerning the above-mentioned light spot condensing position is shown. In this embodiment, the light spots 140, 141, and 1 of the three light beams focused on the CD-ROM disc are used.
42, light collecting position interval Tp6 in the radial direction of the disk
Is set to about 0.4 μm, which is a quarter of the information track pitch of a CD-ROM disc. FIG. 19 and FIG. 2 showing the light spot condensing position on the light receiving surface at this time.
0 and FIG. 21. 19, 20 and 21 show the light spot converging positions on the light receiving surface of the three light beams reflected by the optical disc 14 in the respective light receiving surface patterns.

No matter which light-receiving surface pattern is used, the CD
-When reproducing a ROM disc or a written CD-R disc and a CD-RW disc, a focus error is generated by using the signal of the astigmatism method obtained from the output signals a1, b1, c1, d1 of the light receiving region 200. The tracking error signal is detected by the 3-spot method by detecting the signal and using the output signals from the light receiving area 201 and the light receiving area 202.

The light spot condensing position on the light receiving surface of the disc reflected light of the disc optical spot 141 and the disc reflected light of the disc optical spot 142 is shown in FIG.
It is not limited to FIG. 9, FIG. 20 and FIG. For example, the disc reflected light of the disc light spot 141 is condensed on the light receiving region 203, and the disc reflected light of the disc light spot 142 is condensed on the light receiving region 204 to form detection light spots 151, 152. It doesn't matter. At this time, when reproducing the CD-ROM disc or the written CD-R disc and CD-RW disc, the output signals a1, b1, and
The focus error signal is detected by the astigmatism method by using c1 and d1, and the tracking error signal is detected by the three-spot method by using the output signals from the light receiving area 203 and the light receiving area 204. Regarding the signal processing in the detection method shown above,
As described above, JP-A-2000-082226 and Japanese Patent Application No. 2
Since it is described in detail in No. 000-371484, it will be omitted.

Next, FIG. 22 shows a schematic block diagram of an optical disk device equipped with the optical pickup device of the present invention.
The optical pickup device 30 has a configuration as shown in FIGS. 1, 6, and 12, for example.
The various detection signals detected by are sent to the servo signal generation circuit 164 and the information signal reproduction circuit 165 in the signal processing circuit. In the servo signal generation circuit 164, a focus error signal and a tracking error signal suitable for each optical disc are generated from these detection signals, and based on the generated focus error signal and tracking error signal, the optical pickup device 30 passes through an actuator drive circuit 163.
The objective lens actuator inside is driven to control the position of the objective lens. The information signal reproducing circuit 165 reproduces the information signal recorded on the optical disc 100 from the detection signal. A part of the signals obtained by the servo signal generation circuit 164 and the information signal reproduction circuit 165 is sent to the control circuit 160. Control circuit 160
Discriminates the type of the optical disc 100 to be reproduced at that time using these various signals, and drives either the DVD laser lighting circuit 167 or the CD laser lighting circuit 166 according to the discrimination result. As described above, the servo signal generation circuit 164 selects the servo signal detection method according to the type of each optical disk.
It has a function of switching the circuit configuration. An access control circuit 162 and a spindle motor drive circuit 161 are connected to the control circuit 160, and the access direction position control of the optical pickup device 30 and the rotation control of the spindle motor 169 of the optical disc 100 are performed respectively.

[0070]

As described above, according to the present invention, the five light beams are condensed on the optical disk, and the light beam used for the servo signal detection is selected according to the optical disk to be reproduced or recorded. It is possible to realize an optical pickup device capable of recording and reproducing information on, for example, a DVD-R disc or a DVD-RAM disc having different pitches.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a first embodiment of an optical pickup device according to the present invention.

FIG. 2 is a diagram showing an example relating to a light spot focusing position on an optical disc 7. (A) In case of DVD-R disc or DVD-RW disc (b) In case of DVD-RAM disc

FIG. 3 is a diagram showing a first embodiment regarding a light receiving surface pattern in a photodetector 9a and a light spot condensing position on the light receiving surface.

FIG. 4 is a diagram showing a second embodiment regarding a light receiving surface pattern in a photodetector 9a and a light spot condensing position on the light receiving surface.

FIG. 5 is a diagram showing a third embodiment relating to a light receiving surface pattern in the photodetector 9a and a light spot condensing position on the light receiving surface.

FIG. 6 is a schematic view showing a second embodiment of the optical pickup device according to the present invention.

FIG. 7 is a diagram showing a first embodiment relating to a light spot converging position on an optical disc. (A) CD-ROM disc (b) CD-R disc or CD-RW disc

FIG. 8 is a diagram showing a first embodiment relating to a light receiving surface pattern in a photodetector 9b and a light spot condensing position on the light receiving surface.

FIG. 9 is a diagram showing a second embodiment regarding a light receiving surface pattern in the photodetector 9b and a light spot condensing position on the light receiving surface.

FIG. 10 is a diagram showing a diffraction grating having a rectangular groove.

FIG. 11 is a diagram showing the relationship between the grating groove depth and the diffracted light intensity.

FIG. 12 is a schematic diagram showing a third embodiment of the optical pickup device of the present invention, showing a state where the optical disc 7 is being reproduced or recorded.

FIG. 13 is a schematic view showing a third embodiment of the optical pickup device of the present invention, showing a state where the optical disc 14 is being reproduced or recorded.

FIG. 14 is a diagram showing a second embodiment regarding a light spot focusing position on the optical disc.

FIG. 15 is a first diagram showing light spot condensing positions on a light receiving surface of three light beams reflected by the optical disc.

FIG. 16 is a second diagram showing the light spot condensing positions on the light receiving surface of the three light beams reflected by the optical disc.

FIG. 17 is a third diagram showing the light spot converging positions on the light-receiving surface of three light beams reflected by the optical disc.

FIG. 18 is a diagram showing a third embodiment relating to the light spot converging position on the optical disc.

FIG. 19 is a fourth diagram showing the light spot condensing positions on the light receiving surface of the three light beams reflected by the optical disc.

FIG. 20 is a fifth diagram showing the light spot condensing positions on the light-receiving surface of three light beams reflected by the optical disc.

FIG. 21 is a sixth diagram showing the light spot condensing positions on the light-receiving surface of three light beams reflected by the optical disc.

FIG. 22 is a schematic block diagram of an optical disk device equipped with the optical pickup device of the present invention.

[Explanation of symbols]

1a, 1b ... Semiconductor laser, 2a, 2b, 20 ... Diffraction grating, 3, 4a, 4b, 4c ... Beam splitter, 5a, 5b, 5c ... Collimating lens, 6a, 6b, 6c. ..Objective lens, 7, 14, 100 ... Optical disk, 8a, 8b, 8c ... Detection lens, 9a, 9b, 9c ... Photodetector, 10a, 10b, 10c ... Actuator, 11a, 11b, 11c ... Coil, 100, 101, 102, 103, 104 ... Optical spot on disk, 120, 121, 122, 123, 124 ... Optical spot on disk, 140, 141, 142 ... Optical spot on disk, 110, 111, 112, 113, 114 ... Optical spot on light receiving surface, 130, 131, 132, 133, 34 ... Light spot on light receiving surface, 150, 151, 152 ... Light spot on light receiving surface, 200, 201, 202, 203, 204 ... Light receiving area, 210, 211, 212, 213, 214 ...・ Light receiving area, 40, 41, 42, 43, 44, 45, 46, 47
・ Current-voltage conversion amplifiers, 61, 62, 63, 64, 65, 66, 67, 68
Current / voltage conversion amplifier, 50, 51, 52, 53, 56, 80, 81, 82, 8
3, 86 ... Adder, 54, 55, 57, 58, 60, 84, 85, 87, 8
8, 90 ... Subtractor, 59, 89 ... Amplifier of amplification factor K2, 70, 71, 73 ... Changeover switch, 30 ... Optical pickup device, 72 ... Phase difference detection circuit, 160・ ・ ・ Control circuit, 161 ・ ・ ・ Spindle motor drive circuit, 162 ・ ・ ・ Access control circuit, 163 ・ ・ ・ Actuator drive circuit, 164 ・ ・ ・ Servo signal generation circuit, 165 ・ ・ ・ Information signal reproduction circuit, 166・ ・ ・ CD laser lighting circuit, 167 ・ ・ ・ DVD laser lighting circuit

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   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Kuniichi Onishi             292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa             Ceremony Hitachi Digital Media Development Book             Department (72) Inventor Toshio Sugiyama             No. 1 Kitano, Majo, Mizushiro City, Iwate Prefecture             Within Hitachi Media Electronics (72) Inventor Nobuhiro Onuma             No. 1 Kitano, Majo, Mizushiro City, Iwate Prefecture             Within Hitachi Media Electronics (72) Inventor Akio Yabe             292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa             Ceremony company Hitachi Image Information System (72) Inventor Naoki Ito             No. 1 Kitano, Majo, Mizushiro City, Iwate Prefecture             Within Hitachi Media Electronics (72) Inventor Kazuhiro Todori             No. 1 Kitano, Majo, Mizushiro City, Iwate Prefecture             Within Hitachi Media Electronics (72) Inventor Daisuke Tomita             No. 1 Kitano, Majo, Mizushiro City, Iwate Prefecture             Within Hitachi Media Electronics F-term (reference) 5D118 AA01 AA14 AA26 BA01 BB05                       BF02 BF03 CF05 CG05 CG24                 5D119 AA23 AA41 BA01 BB03 DA01                       DA05 EA01 FA05 FA08 JA06                       JA27 KA20 KA24

Claims (7)

[Claims] 1. One or a plurality of semiconductor laser light sources,
An optical branching element for branching at least one light beam out of the light beams emitted from the semiconductor laser light source into at least five light beams, and condensing the five light beams to form an optical information recording medium. An optical pickup device comprising: a condensing optical system for irradiating five light spots; and a photodetector for receiving the five light beams reflected by the optical information recording medium. 2. The optical pickup device according to claim 1, wherein the irradiation positions of the five light spots on the optical information recording medium are different from each other in the radial direction of the optical information recording medium. The optical pickup device is characterized in that the irradiation position interval in the direction is approximately one-half or approximately one-quarter of the pitch of the guide grooves provided in advance on the optical information recording medium. 3. The optical pickup device according to claim 1, wherein the photodetector has first, second, and fifth positions at which each of the five light beams reflected by the optical information recording medium is irradiated. An optical pickup device comprising third, fourth and fifth light receiving regions. 4. The optical pickup device according to claim 1, wherein at least one light receiving area among the first, second, third, fourth and fifth light receiving areas has a squared shape. An optical pickup device comprising a divided light receiving surface. 5. The optical pickup device according to any one of claims 1 to 4, wherein the light branching element is a linear diffraction grating having a rectangular linear grating groove pattern, and the five light beams are the straight lines. An optical pickup device characterized by being 0th order light, + 1st order light, -1st order light, + 2nd order light and -2nd order light among the light beams diffracted and separated by the linear diffraction grating. 6. A photodetector used in the optical pickup device according to claim 1, wherein five divided light receiving surfaces, two divided light receiving surfaces or non-divided light receiving surfaces are arranged linearly. Characteristic photo detector. 7. An optical information recording / reproducing device equipped with the optical pickup device according to claim 1.