JP2003151169A - Optical head and optical disk playback device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain the realization of the cost reduction and also the simplification of the optical arrangement and the easy adjustment of an optical system in an optical head capable of playing back a DVD, a CD, and recording/playing- back or playing back a CD-R. SOLUTION: An optical element in which a semiconductor laser 2 of 650 nm wavelength for DVD and a photodetecting part 3 are arranged in the same package is provided as an integrating optical element 1, and a semiconductor laser 7 of 780 nm wavelength for CD/CD-R is provided outside the integrating optical element 1. A return light from the optical disk 10 is received by the photodetecting part 3 in the integrating optical element 1 in either cases the optical disk 10 is DVD, CD or CD-R. Inversely, the semiconductor laser 2 in the inside of the integrated optical element 1 emits the laser beam of 780 nm wavelength for CD/CD-R, the outside semiconductor laser 7 emits the laser beam of 650 nm wavelength for DVD, alternatively.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical head for reproducing two kinds of optical disks reproduced by lights having different wavelengths, and an optical disk reproducing apparatus for reproducing two kinds of optical disks by the optical heads.

[0002]

2. Description of the Related Art DVD (D
When reproducing an optical disc of the Digital Versatile Disc type and an optical disc of the CD (Compact Disc) type, it is desirable that one optical head can reproduce the DVD type disc and the CD type disc.

However, DVD discs have a wavelength of 650 nm.
While it is standardized to reproduce by the light of wavelength, the CD-R (CD-Rec
ordable: CD that can be written only once) is 7
It is standardized to record and reproduce with light having a wavelength of 80 nm.

Therefore, in order to enable reproduction or recording / reproduction of a CD-R, one optical head has a wavelength of 650.
A laser that emits a laser beam having a wavelength of 780 nm and a laser that emits a laser beam having a wavelength of 780 nm are required.

As such an optical head, firstly, D
For both the VD type disc and the CD type disc, it is considered to use an integrated optical element in which a laser and a light receiving portion are arranged in the same package. This is the wavelength 65
A 0 nm laser and a light receiving part for receiving the return light from the DVD type disc due to the emitted light are arranged in the same package to form a first integrated optical element for the DVD type disc, and a wavelength of 780 nm is set. A laser and a light receiving unit for receiving the return light from the CD-based disc due to the emitted light are arranged in the same package to form a second integrated optical element for the CD-based disc. The optical system for optical path synthesis and optical path separation is arranged between the integrated optical element and the objective lens.

Secondly, it is considered that the integrated optical element is used only for one of the DVD type disc and the CD type disc, and the other one has a laser and a light receiving portion constituted by a discrete optical system.

Thirdly, for DVD discs and C
No integrated optical element is used for any of the D-system discs,
A laser having a wavelength of 650 nm, a laser having a wavelength of 780 nm, and a common light receiving unit are all considered to be configured by a discrete optical system.

[0008]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
The optical head using the integrated optical element for both the system type disc and the CD type disc requires two light receiving portions, and the emitted light of the laser in each integrated type optical element enters the objective lens. In addition to the optical system for synthesizing the optical paths, the return light from the DVD disc is made incident on the light receiving portion in the first integrated optical element, and the return light from the CD disc is in the second integrated optical element. Since an optical system for separating the optical path to be incident on the light receiving portion of is required, the cost is increased.

Further, an optical head in which an integrated optical element is used only for one of a DVD disc and a CD disc, and the other one has a laser and a light receiving portion formed by a discrete optical system, requires two light receiving portions. Since,
The cost will increase.

Further, a laser having a wavelength of 650 nm and a wavelength of 7
The optical head in which the 80 nm laser and the common light receiving part are all configured by the discrete optical system has a complicated optical arrangement and is designed so that the common light receiving part is at an appropriate position for two lasers at the same time. It is difficult to adjust the system.

Therefore, according to the present invention, in an optical head for reproducing two types of optical disks reproduced by lights having different wavelengths, cost reduction can be realized, the optical arrangement can be simplified, and the optical system can be adjusted. It is intended to be easy.

[0012]

An optical head according to the present invention includes an integrated optical element in which a first laser for emitting a laser beam of a first wavelength and a light receiving section are arranged in the same package, and a second optical element. A second laser that emits laser light of a wavelength;
An objective lens that collects the emitted light of the first laser and the emitted light of the second laser on an optical disc, and transmits the emitted light of the first laser and reflects the emitted light of the second laser. Then, the light emitted from the first laser and the light emitted from the second laser are made incident on the objective lens, and the light returned from the optical disc by the light emitted from the first laser and the second laser are emitted. And a light branching element that transmits the return light from the optical disk due to the emitted light and makes it enter the light receiving portion.

In the optical head of the present invention having such a structure, only one light receiving section is required, and an optical system for separating the optical paths for making the return light from the two types of optical disks incident on the corresponding light receiving sections is required. Therefore, the cost of the optical head can be reduced.

Moreover, since the light receiving portion of the optical system dedicated to the second type optical disk may be replaced with the light receiving portion in the integrated optical element, the optical arrangement is simplified and the integrated optical element is used. Simply adjust the position on the element side
It is possible to adjust the optical system so that the common light-receiving portion can be in an appropriate position at the same time for the two lasers without adjusting the laser side, and the adjustment of the optical system becomes easy.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of an optical head and an optical disk reproducing apparatus of the present invention will be described by taking as an example the case where DVD reproduction, CD reproduction, and CD-R recording / reproduction or reproduction are possible.

[Embodiment of optical head ... FIGS. 1 to 19]
FIG. 1 shows a first embodiment of the optical head of the present invention.

In this embodiment, as the integrated optical element 1, a semiconductor laser (laser diode) 2 having a wavelength of 650 nm for DVD and a light receiving section 3 for DVD and CD / CD-R are provided in the same package. A semiconductor laser (laser diode) 7 having a wavelength of 780 nm for CD / CD-R is provided outside the integrated optical element 1 by providing the arranged optical elements.
To provide. As an optical system of the optical head, a beam splitter 4, a collimator lens 5, an objective lens 6, a coupling lens 8 and a grating 9 are additionally arranged.

When the optical disk 10 is a DVD, the semiconductor laser 2 in the integrated optical element 1 is used as a light source, and the return light from the optical disk 10 is received by the light receiving section 3 in the integrated optical element 1.

That is, in this case, the laser light having a wavelength of 650 nm from the semiconductor laser 2 enters the beam splitter 4 from the integrated optical element 1 as the emitted light Ba and passes through the light branching film 4 a of the beam splitter 4. , Is incident on the collimator lens 5, is collimated by the collimator lens 5, is incident on the objective lens 6, and is condensed on the optical disc 10 by the objective lens 6.

The laser light incident on the optical disk 10 is reflected by the recording surface 10a of the optical disk 10, and as the return light Bb, sequentially passes through the objective lens 6, the collimator lens 5, and the light branching film 4a of the beam splitter 4, The light enters the integrated optical element 1 and is received by the light receiving unit 3.

When the optical disk 10 is a CD or a CD-R, the semiconductor laser 7 outside the integrated optical element 1 is used as a light source, and the return light from the optical disk 10 is received by the light receiving section 3 in the integrated optical element 1. To do.

That is, in this case, the laser light having the wavelength of 780 nm from the semiconductor laser 7 is coupled to the coupling lens 8.
Is increased by the beam splitter 4, is diffracted by the grating 9 and is incident on the beam splitter 4.
The light is reflected by a, enters the collimator lens 5, is collimated by the collimator lens 5, and enters the objective lens 6.
It is condensed on the optical disk 10 by the objective lens 6.

The laser light incident on the optical disk 10 is reflected by the recording surface 10a of the optical disk 10, and as the return light Bb, sequentially passes through the objective lens 6, the collimator lens 5, and the light branching film 4a of the beam splitter 4, The light enters the integrated optical element 1 and is received by the light receiving unit 3.

The grating 9 is for detecting a tracking error at the time of CD / CD-R reproduction and CD-R recording, and by this, in the track direction of the optical disk 10 (circumferential direction: a direction perpendicular to the paper surface of FIG. 1). Three beams are formed.

As the light branching film 4a of the beam splitter 4, all the laser light with a wavelength of 650 nm is transmitted and the wavelength of 7
An optimum amount of light can be guided to the light receiving unit 3 by forming a multilayer film that allows semitransmission of the 80 nm laser light.

(First Example of Integrated Optical Element 1 ... FIGS. 2 to 6) FIG. 2 shows a first example of the integrated optical element 1, and FIG.
An example of the light receiving unit 3 in that case is shown in FIG.

In this example, the integrated optical element 1 has a laser coupler structure, laser chips 2a are formed on a base 11a of a silicon substrate 11, and the laser chips 2a are arranged on the silicon substrate 11 in the radial direction of the optical disk 10 to receive light. (Photodiodes) 12 and 13 are formed, and the microprism 19 is mounted on the silicon substrate 11 on the light receiving elements 12 and 13.

Laser chip 2a of micro prism 19
The wavelength of 650 for DVD is on the 45 ° inclined surface facing the
The optical branching film 19a which semi-transmits the laser light of wavelength nm and transmits all the laser light of wavelength 780 nm for CD / CD-R.
To form. Further, for both wavelengths of 650 nm and 780 nm, a semi-transmissive film 19b is provided on the bottom surface of the light receiving element 12 of the micro prism 19 and a reflective film 19c is provided on the upper surface thereof.
A transparent film 19d is formed on the bottom surface of the light receiving element 13.

As a result, the laser light having a wavelength of 650 nm emitted from the laser chip 2a is reflected by the light branching film 19a and enters the optical disc 10 as the emitted light Ba as shown in FIG. Half or all of the return light Bb having a wavelength of 650 nm or 780 nm passes through the light branching film 19a and enters the microprism 19, and half of the light passes through the semitransparent film 19b and enters the light receiving element 12, The other half is a semipermeable membrane 19b
Also, the light is reflected by the reflective film 19c, transmitted through the transmissive film 19d, enters the light receiving element 13, and receives the light receiving element 12 and the light receiving element 13.
Thus, almost the same amount of light is received.

In this case, as shown in FIG. 1, when the laser light from the semiconductor laser 2 (laser chip 2a) or the semiconductor laser 7 is focused on the recording surface 10a of the optical disk 10, as shown in FIG. The optical system is designed so that the return light Bb is focused on the upper surface of the micro prism 19.

As shown in FIG. 3, the light receiving element 12 is divided into two parts in the radial direction and four parts in the track direction to be composed of elements 12a to 12h, and the light receiving element 13 is divided into three parts in the track direction. To be composed of the elements 13i to 13k.

Further, light-receiving elements (photodiodes) 14 and 16 are formed on both sides of the light-receiving element 12 in the track direction. The light-receiving elements 14 and 16 are divided into two in the radial direction, and the elements 14a, 14b and 16
a and 16b, and the light receiving element 13
Light receiving elements (photodiodes) 15 and 17 are formed on both sides in the track direction.

<During DVD playback ... Figure 4> In this example, DV
At the time of D reproduction, the return light Bb from the optical disc 10 is reflected by the light receiving element 12 as shown by the shaded spots in FIG.
It is incident only on (12a to 12h) and 13 (13i to 13k).

Therefore, assuming that the light receiving output signals of the elements 12a to 12h are Sa to Sh and the light receiving output signals of the elements 13i to 13k are Si to Sk, the reproduction signal RF is as shown in equation (1) of FIG. The focus error signal FE can be detected as the sum of the signals Sa to Sk.
By the division method, it can be detected as represented by the equation (2) in the figure.

The tracking error signal TE is D
PD (Differential Phase Dite)
signal), as shown in FIG.
(= Sa + Sb + Sg + Sh) and signal Sy (= Sc + S)
It can be detected as a phase difference of d + Se + Sf).

<During CD / CD-R Reproduction and CD-R Recording ... FIG. 5> During CD / CD-R reproduction and CD-R recording, as shown in FIG. The return light from the optical disk 10 due to the 0th order light is
Light receiving elements 12 (12a to 12h) and 13 (13i to)
13k) and is diffracted by the grating 9 + 1
The return light from the optical disk 10 due to the next light is received by the light receiving element 1
The return light from the optical disk 10 which is incident on the light beams 4 (14a, 14b) and 15 and is diffracted by the grating 9 and is returned from the optical disk 10 is received by the light receiving elements 16 (16a, 16b) and 1
It is incident on 7.

Therefore, the light receiving output signals of the elements 12a to 12h are Sa to Sh, the light receiving output signals of the elements 13i to 13k are Si to Sk, the light receiving output signals of the elements 14a and 14b are Ta and Tb, and the light receiving output signal of the element 15 is. Tc, element 16
Assuming that the light receiving output signals of a and 16b are Ua and Ub and the light receiving output signal of the element 17 is Uc, the reproduction signal (recording signal at the time of CD-R recording) RF is as shown by the equation (1) in FIG.
It can be detected as the sum of the signals Sa to Sk, and the focus error signal FE can be detected as the one expressed by the equation (2) in the figure by the differential division method.

The tracking error signal TE is D
PP (Differential push-pull)
It can be detected by the method as represented by the equation (3) in the figure.

As described above, when the tracking error signal TE is detected by the DPP method during CD / CD-R reproduction and CD-R recording, the light receiving element 15 is combined with the DVD reproduction shown in FIG. And 17 are unnecessary.

However, during CD / CD-R reproduction, the tracking error signal TE can also be detected by the three-beam method instead of the DPP method as represented by the equation (4) in FIG. Requires the light receiving elements 15 and 17.

<When CD-R recording is not performed ... FIG. 6>
As described above, at the time of CD / CD-R reproduction, the tracking error signal TE can be detected as represented by the equation (4) in FIG. 5 by the three-beam method, so that the CD-R recording is performed. In the optical head which does not have such a structure, as shown in FIG. 6, the light receiving elements 14 and 16 do not need to be divided into two in the radial direction.

In this case, assuming that the light receiving output signals of the light receiving elements 14 and 16 are Ta and Ua, the tracking error signal TE at the time of CD / CD-R reproduction is expressed by the formula (5) of FIG. 6 by the three-beam method. Can be detected as being.

(Second Example of Integrated Optical Element 1 ... FIGS. 7 to 13) FIG. 7 shows a second example of the integrated optical element 1 and FIG. 8 shows an example of the light receiving portion 3 in that case. Indicates. FIG. 9 corresponds to FIG.
FIG. 3 is a cross-sectional view of a laser chip formation portion of

In this example, the groove 11b is formed in the center of the silicon substrate 11, the base 11c is formed in the center of the groove 11b, the laser chip 2a is formed on the base 11c, and the groove 1 is formed.
A reflecting surface 11d of 45 ° is formed on one side surface of 1b, light receiving elements 12 and 13 are formed on a silicon substrate 11 on both sides of the laser chip 2a in the radial direction, and a hologram element 21 is arranged above the silicon substrate 11. To do.

The hologram element 21 has hologram surfaces 21aL and 21aR which divide the return light Bb from the optical disc 10 into two, which are formed on the upper surface as the hologram surface 21a, and a three-beam grating 21b is formed on the lower surface, if necessary. Form.

Wavelength 650 emitted from laser chip 2a
The laser light of nm is reflected by the reflecting surface 11d and emitted light B
As a, while passing through the hologram surface 21a and entering the optical disc 10 as shown in FIG. 1, the return light Bb having a wavelength of 650 nm or a wavelength of 780 nm from the optical disc 10 is diffracted by the hologram regions 21aL and 21aR, and respectively. Of the + 1st order lights BpL and BpR of the light receiving element 1
2, and the −first-order lights BmL and BmR are incident on the light receiving element 13.

In this case, when the laser light from the semiconductor laser 2 (laser chip 2a) or the semiconductor laser 7 is focused on the recording surface 10a of the optical disc 10 as shown in FIG. 1, as shown in FIG. The + first-order lights BpL and BpR are before focusing on the light-receiving surface of the light-receiving element 12, and the −1st-order lights Bm
The optical system is designed so that L and BmR are after focusing on the light receiving surface of the light receiving element 13.

As shown in FIG. 8, the light receiving element 12 is divided into two in the radial direction and four in the track direction to be composed of elements 12a to 12h. The light receiving element 13 is also divided into two in the radial direction. , And is divided into four in the track direction and is composed of elements 13i to 13p.

Further, light receiving elements 14 and 16 are formed on both sides of the light receiving element 12 in the track direction. The light receiving elements 14 and 16 are divided into two in the radial direction, and the elements 14a, 14b and 16a, 16b are separated from each other. In addition, the light receiving elements 15 and 17 are formed on both sides of the light receiving element 13 in the track direction, and the light receiving elements 15 and 17 are also divided into two in the radial direction, and the elements 15c, 15d and 17c, 17d are formed. Shall consist of

<DVD Reproduction ... FIG. 10 and FIG. 11> In this example, if the three-beam grating 21b is not formed on the lower surface of the hologram element 21, DV is used.
At the time of D reproduction, the return light Bb from the optical disk 10 is diffracted by the hologram areas 21aL and 21aR, and as shown by the shaded spots in FIG.
The + 1st-order light BpL of aL enters the elements 12a to 12d,
The + 1st order light BpR of the hologram area 21aR is the element 12e.
To 12h, the −1st-order light BmL of the hologram area 21aL enters the elements 13m to 13p, and the −1st-order light BmR of the hologram area 21aR enters the elements 13i to 13l.

Therefore, assuming that the light receiving output signals of the elements 12a to 12h are Sa to Sh and the light receiving output signals of the elements 13i to 13p are Si to Sp, the reproduction signal RF is as shown by the equation (11) in FIG. It can be detected as the sum of the signals Sa to Sp, and the focus error signal FE can be detected as the one expressed by the equation (12) in the figure by the differential division method.

The tracking error signal TE is D
According to the PD method, as shown in the figure, the signal Sx (= Sa
+ Sb + Sg + Sh + So + Sp + Si + Sj) and the signal Sy (= Sc + Sd + Se + Sf + Sm + Sn + Sk +).
It can be detected as a phase difference of S1).

On the other hand, when the three-beam grating 21b is formed on the lower surface of the hologram element 21, during the DVD reproduction, as shown in FIG. 11, the + 1st order lights BpL, BpR of the hologram areas 21aL, 21aR and The 0th-order lights of the −1st-order lights BmL and BmR that have passed through the grating 21b are the elements 12a to 12d and 12e to 12h.
And 13m to 13p, 13i to 13l, and the + 1st order light diffracted by the grating 21b is reflected by the element 14
The -1st-order light which is incident on a, 14b and 15d, 15c and is diffracted by the grating 21b is reflected by the elements 16a, 16a.
It is incident on b and 17d and 17c.

However, when the DVD is reproduced, even if the grating 21b is present as described above, the grating 2
Similarly to the case where 1b does not exist, the reproduction signal RF is as the sum of the signals Sa to Sp, as shown in Expression (11).
The focus error signal FE is
As represented by the equation (12), the tracking error signal TE is the signal Sx (= Sa + S) by the DPD method.
b + Sg + Sh + So + Sp + Si + Sj) and the signal Sy
(= Sc + Sd + Se + Sf + Sm + Sn + Sk + S
It can be detected as the phase difference of l).

However, when the three-beam grating 21b is formed on the lower surface of the hologram element 21, D
VD-RAM (DVD-Random Access
Memory), DVD-RW (DVD-Rewrite)
Able), DVD-R (DVD-Recordable)
The tracking error signal TE can be detected by the DPP method at the time of recording / reproducing such as e), the following CD / CD-R reproducing and CD-R recording.
-Recording / reproducing of RAM, DVD-RW, DVD-R, etc. can be performed.

<CD / CD-R Reproduction and CD-R Recording ... FIG. 12> During CD / CD-R reproduction and CD-R recording, as shown in FIG. 12, the grating 9 of FIG. 1 is transmitted. + 1st order light BpL, BpR and −1st order light BmL, B of the return light from the optical disk 10 by the 0th order light, which is diffracted by the hologram areas 21aL, 21aR of FIG.
mR includes elements 12a-12d, 12e-12h and 1
+ 1st order light BpL, BpR and −1st order light BmL diffracted by the hologram regions 21aL and 21aR of the return light from the optical disc 10 which is incident on 3m to 13p and 13i to 13l and is diffracted by the grating 9. , B
mR is incident on the elements 14a, 14b and 15d, 15c, and the hologram area 21a of the return light from the optical disk 10 by the -1st-order light diffracted by the grating 9
The + 1st order lights BpL and BpR and the −1st order lights BmL and BmR diffracted by L and 21aR are incident on the elements 16a and 16b and 17d and 17c.

Therefore, the light reception output signals of the elements 12a to 12h are Sa to Sh, the light reception output signals of the elements 13i to 13p are Si to Sp, the light reception output signals of the elements 14a and 14b are Ta and Tb, and the light reception output signals of the elements 15c and 15d. Output signal is T
c, Td, the light reception output signals of the elements 16a and 16b are Ua,
Ub, the light reception output signals of the elements 17c and 17d are set to Uc and Ud.
Then, the reproduction signal (recording signal during CD-R recording) R
F is the signal Sa to S as shown by the equation (11) in FIG.
The focus error signal FE can be detected as the sum of p, and the focus error signal FE can be detected by the differential three-division method using the equation (12).
Can be detected as

The tracking error signal TE is D
By the PP method, it can be detected as represented by the equation (13) in the figure.

However, at the time of CD / CD-R reproduction, the tracking error signal TE can be detected as the one expressed by the equation (14) in FIG. 12 by the three-beam method instead of the DPP method.

<When CD-R recording is not performed ... FIG. 13
> As described above, at the time of CD / CD-R reproduction, the tracking error signal TE can be detected as represented by the equation (14) in FIG. 12 by the three-beam method. With an optical head that does not perform,
As shown in, each of the light receiving elements 14 to 17 does not need to be divided into two in the radial direction.

In this case, the light receiving elements 14, 15, 16, 1
If the light receiving output signals of 7 are Ta, Tc, Ua, Uc,
Tracking error signal TE during CD / CD-R playback
Can be detected by the 3-beam method as represented by equation (15) in FIG.

(Third Example of Integrated Optical Element 1 ... FIG. 14 to FIG.
18) FIG. 14 shows a third example of the integrated optical element 1, and FIG. 15 shows an example of the light receiving section 3 in that case.

In this example, similarly to the second example, the laser chip 2a is formed on the table portion in the groove of the silicon substrate 11,
The reflection surface 11d of 45 ° is formed on one side surface of the groove, and the hologram element 21 is arranged above the silicon substrate 11. However, unlike the second example, the hologram element 21 has a hologram surface 21a on the upper surface. Hologram regions 21aU, 21aL that divide the return light Bb from the optical disc 10 into three,
21aR is formed, and the laser chip 2 is used as the light receiving portion 3.
On one side in the radial direction of a, the light receiving elements (photodiodes) 32c, 31c, 33 are formed on the silicon substrate 11.
c, 32a, 31a, 31b, 33a, 32d, 31
d and 33d are arranged in the track direction.

The light-receiving elements 31a and 31b are formed in two parts which are adjacent to each other, and the lower surface of the hologram element 21 is provided with a grating 21b for three beams, if necessary.
To form.

Wavelength 650 emitted from laser chip 2a
The laser light of nm is reflected by the reflecting surface 11d and emitted light B
As a, while passing through the hologram surface 21a and entering the optical disc 10 as shown in FIG. 1, the return light Bb having a wavelength of 650 nm or a wavelength of 780 nm from the optical disc 10 is generated in the hologram regions 21aU, 21aL, 21a.
The + 1st order light B of the hologram area 21aU after being diffracted by R
pU enters the light receiving elements 31a and 31b, the + 1st order light BpL of the hologram area 21aL enters the light receiving element 31d, and the + 1st order light BpR of the hologram area 21aR enters the light receiving element 31c.

In this case, when the laser light from the semiconductor laser 2 (laser chip 2a) or the semiconductor laser 7 is focused on the recording surface 10a of the optical disk 10 as shown in FIG. 1, as shown in FIG. + 1st-order light Bp (BpU, B
The optical system is designed so that (pL, BpR) is focused on the light receiving surface of the light receiving unit 3.

<DVD playback ... FIG. 16 and FIG. 17> In this example, when the three-beam grating 21b is not formed on the lower surface of the hologram element 21, the DV is used.
At the time of D reproduction, the return light Bb from the optical disc 10 is diffracted by the hologram areas 21aU, 21aL, 21aR,
As shown by the shaded spots in FIG. 16, the + 1st order light BpU in the hologram area 21aU is received by the light receiving elements 31a, 3a.
1b, and + 1st order light Bp of hologram area 21aL
L enters the light receiving element 31d, and the hologram area 21aR
+ 1st order light BpR enters the light receiving element 31c.

Therefore, the light receiving elements 31a, 31b, 3
The light receiving output signals of 1c and 31d are set to Sa, Sb, Sc and Sd.
Then, the reproduction signal RF can be detected as the sum of the signals Sa to Sd as shown in the equation (21) of FIG. 16, and the focus error signal FE can be detected by the equation (22) of the figure by the knife edge method. ), The tracking error signal TE can be detected by the DPD method as a phase difference between the signal Sc and the signal Sd as shown in FIG.

On the other hand, when the three-beam grating 21b is formed on the lower surface of the hologram element 21, when the DVD is reproduced, as shown in FIG. 17, the grating 21b of the + 1st order light BpU of the hologram area 21aU is formed.
The 0th-order light transmitted through is incident on the light receiving elements 31a and 31b, the + 1st-order light diffracted by the grating 21b is incident on the light-receiving element 32a, and the -1st-order light diffracted by the grating 21b is received by the light-receiving element 33a. Incident on the grating 21 of the + 1st order light BpL of the hologram area 21aL.
The 0th order light transmitted through b is incident on the light receiving element 31d, and the + 1st order light diffracted by the grating 21b is received by the light receiving element 3d.
It is incident on 2d and is diffracted by the grating 21b-1.
The next light enters the light receiving element 33d, and the hologram area 21
The 0th-order light of the aR + 1st-order light BpR that has passed through the grating 21b enters the light receiving element 31c, and the + 1st-order light diffracted by the grating 21b enters the light receiving element 32c and is diffracted by the grating 21b. The primary light is
It is incident on the light receiving element 33c.

However, when the DVD is reproduced, even if the grating 21b is present as described above, the grating 2
Similarly to the case where 1b does not exist, the reproduction signal RF is as the sum of the signals Sa to Sd, as shown in Expression (21).
The focus error signal FE is represented by the equation (22) by the knife edge method, and the tracking error signal TE is represented by the signal Sc and the signal S by the DPD method.
Each can be detected as a phase difference of d.

However, when the three-beam grating 21b is formed on the lower surface of the hologram element 21, D
The tracking error signal TE can be detected by the DPP method during recording / reproduction of VD-RAM, DVD-RW, DVD-R, etc., as well as during the following CD / CD-R reproduction and CD-R recording. , DVD-RAM, DVD
-Recording and reproducing of RW, DVD-R, etc. can be performed.

<CD / CD-R Reproduction and CD-R Recording ... FIG. 18> During CD / CD-R reproduction and CD-R recording, as shown in FIG. 18, the grating 9 of FIG. 1 is transmitted. The light returned from the optical disc 10 by the 0th order light, which is diffracted in the hologram area 21aU of FIG. 14, enters the light receiving elements 31a and 31b, and the light diffracted in the hologram area 21aL enters the light receiving element 31d. ,
The light diffracted by the hologram area 21aR is received by the light receiving element 3
The light returned from the optical disc 10 by the + 1st order light that is incident on 1c and is diffracted by the grating 9 and is diffracted by the hologram area 21aU is incident on the light receiving element 32a.
The light diffracted by the hologram area 21aL is received by the light receiving element 3
The light that is incident on 2d and is diffracted by the hologram area 21aR is incident on the light receiving element 32c and is the return light from the optical disc 10 due to the −1st order light that is diffracted by the grating 9.
The light diffracted by the hologram area 21aU is received by the light receiving element 3
The light that has entered the hologram area 21aL is diffracted by the hologram area 21aL.
The light diffracted by is incident on the light receiving element 33c.

Therefore, the light receiving elements 31a, 31b, 3
1c, 31d received light output signals Sa, Sb, Sc, S
d, the light receiving output signals of the light receiving elements 32a, 32c, 32d are Ta, Tc, Td, and the light receiving output signals of the light receiving elements 33a, 33c, 33d are Ua, Uc, Ud. ) RF can be detected as the sum of the signals Sa to Sd as shown in the equation (21) in FIG. 18, and the focus error signal FE is expressed by the equation (22) in the figure by the knife edge method. It can be detected as one.

The tracking error signal TE is D
By the PP method, it can be detected as represented by the equation (23) in the figure.

As described above, when the tracking error signal TE is detected by the DPP method during CD / CD-R reproduction and CD-R recording, in combination with the DVD reproduction shown in FIGS. 16 and 17, The light receiving elements 32a and 33a are unnecessary.

However, at the time of CD / CD-R reproduction, the tracking error signal TE can be detected as the one expressed by the equation (24) in FIG. 18 by the three-beam method instead of the DPP method. The light receiving element 32a
And 33a are required.

(Other Examples) In each of the above examples, CD / CD-
At the time of R reproduction and CD-R recording, the tracking error signal TE is detected by the DPP method, or CD / CD-
In the case of detecting the tracking error signal TE by the three-beam method at the time of R reproduction, when the CD / CD-R reproduction and the CD-R recording or the CD / CD-R reproduction is performed, the push-pull method is used. In the equation (3) of FIG. 12, the equation (13) of FIG. 12, and the equation (23) of FIG. 18, as the signal having no term multiplied by the constant k, the tracking error signal T
E can also be detected, and in that case, the grating 9 of FIG. 1 is unnecessary, and in the first example of FIGS. 2 to 6 and the second example of FIGS. 14
~ 17 is unnecessary, and in the third example of Figs.
Light receiving elements 32a, 33a, 32c, 33c, 32d, 3
3d is unnecessary.

Further, when the power of the emitted light of the semiconductor laser 7 of FIG. 1 is not so required as in the case of not recording the CD-R, the coupling lens 8 is also unnecessary.

Other Embodiments ... FIG. 19 In the embodiment shown in FIG. 1, that is, in each of the examples described above, the semiconductor laser 2 in the integrated optical element 1 emits a laser beam having a wavelength of 650 nm for DVD, External semiconductor laser 7 CD / CD
In the case of emitting laser light of wavelength 780 nm for −R, conversely, as shown in FIG. 19, the semiconductor laser 2 in the integrated optical element 1 is set to the wavelength 780 nm for CD / CD-R. Alternatively, the external semiconductor laser 7 may emit laser light having a wavelength of 650 nm for DVD. Also in this case, the integrated optical element 1 can be configured as in each of the examples described above.

[Embodiment of optical disc reproducing apparatus ... FIG. 2]
0] FIG. 20 shows an embodiment of an optical disk reproducing apparatus of the present invention.

The optical head 40 has an optical system as shown in FIG. 1 or 19, and includes a driver for driving the semiconductor lasers 2 and 7 shown in FIG. 1 or 19,
It includes a biaxial actuator 41 for driving the objective lens 6 in the focus direction and the tracking direction.

The optical disk 10 has a spindle motor 51.
The optical head 40 is driven to rotate by the feed motor 52, and the feed mechanism 53 is driven by the feed motor 52.
It is sent in the radial direction of the optical disc 10.

The light receiving output signal of the light receiving portion 3 in the integrated optical element 1 shown in FIG. 1 or FIG. 19 of the optical head 40 is sent from the optical head 40 to the RF amplifier 61, and from the RF amplifier 61 to the DSP (Digital Signal). P
A reproduction signal RF, a focus error signal FE, a tracking error signal TE, etc. are sent to the processor 62. Further, a laser drive signal is sent from the DSP 62 to the optical head 40 through the RF amplifier 61.

The DSP 62 is controlled by the controller 63 to control the driver 54. The driver 54 sends drive signals to the spindle motor 51 and the feed motor 52, respectively, and the optical head 40.
Drive signals for focus control and tracking control are sent to the biaxial actuator 41.

[0085]

As described above, according to the present invention, in the optical head for reproducing two types of optical disks reproduced by lights having different wavelengths, cost reduction can be realized and the optical arrangement can be simplified. Moreover, the adjustment of the optical system becomes easy.

[Brief description of drawings]

FIG. 1 is a diagram showing a first embodiment of an optical head of the present invention.

FIG. 2 is a diagram showing a first example of an integrated optical element.

FIG. 3 is a diagram showing an example of a light receiving section of the integrated optical element of FIG.

FIG. 4 is a diagram for explaining the DVD reproduction of the example of FIG.

5 is a CD / CD-R playback and CD- of the example of FIG.
FIG. 8 is a diagram provided for explaining R recording.

FIG. 6 is a diagram for explaining the CD / CD-R reproduction in the example of FIG. 2;

FIG. 7 is a diagram showing a second example of an integrated optical element.

8 is a diagram showing an example of a light receiving section of the integrated optical element of FIG.

9 is a cross-sectional view of the laser chip forming portion of FIG.

10 is a diagram for explaining the DVD reproduction of the example of FIG. 7. FIG.

FIG. 11 is a diagram for explaining the DVD reproduction of the example of FIG. 7.

FIG. 12 is a diagram showing a CD / CD-R playback and a CD in the example of FIG.
FIG. 6 is a diagram provided for explanation of −R recording.

FIG. 13 is a diagram for explaining the CD / CD-R reproduction of the example of FIG. 7.

FIG. 14 is a diagram showing a third example of an integrated optical element.

15 is a diagram showing an example of a light receiving portion of the integrated optical element of FIG.

16 is a diagram for explaining the DVD reproduction of the example of FIG. 14. FIG.

17 is a diagram for explaining the DVD reproduction of the example of FIG. 14. FIG.

FIG. 18 is a CD / CD-R playback and C of the example of FIG. 14;
FIG. 6 is a diagram provided for explaining a D-R recording.

FIG. 19 is a diagram showing a second embodiment of the optical head of the present invention.

FIG. 20 is a diagram showing an embodiment of an optical disc reproducing apparatus of the present invention.

[Explanation of symbols]

Since the main parts are all described in the figure, they are omitted here.

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 5D118 AA04 AA06 AA26 BA01 BB01                       BB03 CD02 CD03 CF08 DA20                 5D119 AA03 AA41 BA01 BB01 BB02                       EA02 EA03 EC45 EC47 FA08                       FA30 JA10 JA14 KA20                 5D789 AA03 AA41 BA01 BB01 BB02                       EA02 EA03 EC45 EC47 FA08                       FA30 JA10 JA14 KA20

Claims (10)

[Claims] 1. An integrated optical element in which a first laser emitting a laser beam of a first wavelength and a light receiving section are arranged in the same package, and a second laser emitting a laser beam of a second wavelength. An objective lens for converging the emitted light of the first laser and the emitted light of the second laser on an optical disc; and an emitted light of the second laser that transmits the emitted light of the first laser. Of the first laser and the emitted light of the second laser to enter the objective lens, and return light from the optical disc due to the emitted light of the first laser, and the second light. 2. An optical head comprising: an optical branching element that transmits the return light from the optical disk due to the emitted light of the laser and makes it enter the light receiving unit. 2. The optical head according to claim 1, wherein the integrated optical element reflects the emitted light of the first laser toward the optical branching element and causes the return light to enter the light receiving portion. An optical element is provided, and the light receiving section includes first and second light receiving elements arranged in a first direction corresponding to a radial direction of the optical disc, and the first light receiving element is arranged in the first direction. The optical head is divided into two parts and divided into four parts in a second direction corresponding to the track direction of the optical disk, and the second light receiving element is divided into three parts in the second direction. 3. The optical head according to claim 2, further comprising a grating between the second laser and the light branching element, wherein the light receiving section includes the first and second light receiving elements, respectively. An optical head having light-receiving elements on both sides in the direction 2 for receiving return light from the optical disc due to the + 1st-order light and the -1st-order light diffracted by the grating. 4. The optical head according to claim 3, wherein the light-receiving elements on both sides of the first light-receiving element are each divided into two in the first direction. 5. The optical head according to claim 1, wherein each of the integrated optical elements diffracts the return light, and when the laser emission light which is the source of the return light is focused on the optical disc. A hologram element having first and second hologram areas for generating + 1st order light and −1st order light before or after focusing on the light receiving surface of the light receiving section, A first light receiving element, which is arranged in a first direction corresponding to a radial direction and receives the + 1st order light diffracted by the first and second hologram areas, and the first and second hologram areas. A second light receiving element for receiving the diffracted −1st order light is provided, and the first and second light receiving elements are respectively the light diffracted in the first hologram area and the second light receiving area in the second hologram area. The diffracted light Separately while being divided into two in the first direction to receive a second direction four divided optical head corresponding to the track direction of the optical disc. 6. The optical head according to claim 5, further comprising a grating between the second laser and the light branching element, wherein the light receiving section includes the first light receiving element and the second light receiving element, respectively. An optical head having light-receiving elements on both sides in the direction 2 for receiving return light from the optical disc due to the + 1st-order light and the -1st-order light diffracted by the grating. 7. The optical head according to claim 6, wherein the light receiving elements on both sides of the first light receiving element and the second light receiving element are provided.
An optical head in which light-receiving elements on both sides of the light-receiving element are divided into two in the first direction. 8. The optical head according to claim 1, wherein each of the integrated optical elements diffracts the return light, and when the laser emission light that is the source of the return light is focused on the optical disc. A hologram element having first, second and third hologram areas for generating light focused on the light receiving surface of the light receiving section is provided, and the light receiving section is arranged in a direction corresponding to a track direction of the optical disc. In addition, the first light receiving element divided into two for receiving the light diffracted in the first hologram region, the second light receiving element
2. An optical head including a second light receiving element for receiving light diffracted in the hologram area and a third light receiving element for receiving light diffracted in the third hologram area. 9. The optical head according to claim 8, further comprising a grating between the second laser and the light branching element, wherein the light receiving section includes one of the first, second and third light receiving elements. An optical head comprising light-receiving elements on both sides of a direction corresponding to the track direction of the optical disc, which receive return light from the optical disc due to the + 1st-order light and the -1st-order light diffracted by the grating. 10. An optical disk reproducing apparatus comprising the optical head according to claim 1.