JP2004071044A - Optical pickup and disk drive device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To aim at miniaturization of the device by reducing the number of members and to aim at improving the performance. <P>SOLUTION: Three light receiving surfaces of a photo detector 21 are composed of a main beam light receiving surface 22 for receiving a 0-order light and a pair of sub-beam light receiving surfaces 23 and 24 for receiving ±1st light respectively which are located opposite to each other with the main beam light receiving surface 22 in between. The main beam light receiving surface is quatered by two cross-shaped area dividing lines 22a and 22b. On each of the pair of sub-beam light receiving surfaces, the first spot dividing lines 23a and 24a and the second spot dividing lines 23b and 24b for dividing each of light receiving spots of a laser beam having the first wavelength and a laser beam having the second wavelength in the direction in which the three light receiving surfaces are arranged are formed. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to the technical field of an optical pickup and a disk drive. More specifically, in an optical pickup for recording and / or reproducing information signals on and from two different types of disk-shaped recording media, and a disk drive device including the same, a technique for improving the performance and reducing the number of components to reduce the size. About the field.
[0002]
[Prior art]
2. Description of the Related Art There is a disk drive device that records and reproduces information signals on and from a disk-shaped recording medium. Such a disk drive device moves in a radial direction of a disk-shaped recording medium mounted on a disk table and moves the disk-shaped recording medium. And an optical pickup for irradiating a laser beam through an objective lens.
[0003]
2. Description of the Related Art Some disk drive devices record and reproduce information signals on and from two different types of disk-shaped recording media, for example, CDs (Compact Discs) and DVDs (Digital Versatile Discs). In such a disk drive device, it is necessary to use laser light having a wavelength corresponding to each disk-shaped recording medium, but the same light emitting element is used in the disk drive device for the purpose of reducing the number of parts and the like. There is one that emits laser light having different wavelengths by using the same.
[0004]
In such a disk drive device, a laser beam having a wavelength of 780 nm corresponding to CD is emitted from one light emitting point of the light emitting element, and a laser beam having a wavelength of 650 nm corresponding to DVD is emitted from the other light emitting point. Is done.
[0005]
Each laser beam emitted from the light emitting element is diffracted by the same diffractive element (grating) into 0th order light and ± 1st order light, and is reflected on the recording surface of each disk-shaped recording medium. The surfaces receive the 0th-order light and ± 1st-order light, respectively.
[0006]
[Problems to be solved by the invention]
By the way, the diffraction angle θ of laser light (the angle between the 0th-order light and ± 1st-order light) is Pin the grating pitch of the grating (the interval between the grooves of the grating) and Sinθ, where λ is the wavelength of the laser light. = Λ / Pd, and the diffraction angle θ depends on the wavelength λ. Therefore, as described above, when laser light having different wavelengths is diffracted by one diffraction element, the diffraction angle θ differs for each laser light.
[0007]
When the diffraction angle varies depending on the wavelength in this manner, as shown in FIG. 8, the zero-order light Sd and the ± first-order lights Se and Se of one of the laser beams are respectively received by the light receiving surfaces a, b, and c of the light receiving element. When the 0th-order light Sf of the other laser beam is aligned with the center of the light receiving surface a where the 0th-order light Sd is received, ± 1st-order light Sg of the other laser beam, Sg is shifted from the center of each of the light receiving surfaces b and c of the light receiving element. Therefore, when trying to detect a tracking error signal by a method using astigmatism, the push-pull signal cannot be detected for the other laser beam.
[0008]
Therefore, when an optical system is configured using one light emitting element that emits two types of laser lights having different wavelengths and one grating, two light receiving elements for receiving each laser light are required. However, since the number of light receiving elements is two, there is a problem that the manufacturing cost rises due to an increase in the number of parts.
[0009]
On the other hand, in an optical system configured using one light emitting element that emits two types of laser lights having different wavelengths and one grating, for example, only the 0th-order light of the laser light having a wavelength of 650 nm is used and ± 1. It is also possible to adopt a so-called one-beam correspondence (DPD method: Differential Phase Detection method, movable push-pull method) that does not use the next light.
[0010]
However, in this case, the information signal cannot be recorded on the DVD (DVD video, DVD-ROM) by the DPD method, but can be recorded on the DVD-RAM, and the information signal cannot be recorded on the DVD-RAM. Recording and reproduction cannot be performed, and the types of usable disc-shaped recording media are limited. In addition, the movable push-pull method has a problem that the cost is high because an expensive optical element such as a polarization hologram element must be used.
[0011]
Therefore, it is an object of the present invention to overcome the above-mentioned problems, to reduce the number of parts, to reduce the size, and to improve the performance.
[0012]
[Means for Solving the Problems]
In order to solve the above-described problems, the optical pickup and the disk drive device of the present invention have a first wavelength and a second wavelength corresponding to each of the disk-shaped recording media toward two different types of disk-shaped recording media. A light emitting element for emitting laser light, a diffractive element for diffracting laser light having a first wavelength and a laser light having a second wavelength, laser light having a first wavelength and laser light having a second wavelength A beam splitter that reflects or transmits the laser beam according to the traveling direction of each laser beam, and an objective lens that focuses the laser beam having the first wavelength and the laser beam having the second wavelength on the recording track of the disc-shaped recording medium And an optical axis combining element for matching the optical axes of the laser light having the first wavelength and the laser light having the second wavelength reflected by each disk-shaped recording medium A laser beam having a first wavelength and a laser beam having a second wavelength whose optical axes are matched by the optical axis combining element are incident, and the 0th-order light and ± 1st-order light of the laser light are separately separated. A light receiving element having three light receiving surfaces for receiving light is provided, and the three light receiving surfaces of the light receiving element are located on opposite sides of the main beam light receiving surface for receiving the zero-order light and the main beam light receiving surface, respectively. The main beam receiving surface is divided into four parts by two cross-shaped area dividing lines, and each of the pair of sub-beam receiving surfaces has a first wavelength. A first spot division line and a second spot division line for dividing each of the light receiving spots of the laser light and the laser light having the second wavelength in the direction in which the three light receiving surfaces are arranged are formed.
[0013]
According to another aspect of the present invention, there is provided an optical pickup and a disk drive device that aim at two different types of disk-shaped recording media, and a first wavelength and a second wavelength corresponding to each of the disk-shaped recording media. A light emitting element that emits a laser beam having a first wavelength, a diffraction element that diffracts a laser beam having a first wavelength and a laser beam having a second wavelength, and a laser beam that has a first wavelength and a second wavelength. A beam splitter that reflects or transmits the laser light according to the traveling direction of each laser light, and focuses the laser light having the first wavelength and the laser light having the second wavelength on the recording track of the disk-shaped recording medium. Objective lens and optical axis combining for matching the optical axes of the laser light having the first wavelength and the laser light having the second wavelength reflected by each disk-shaped recording medium And a laser beam having a first wavelength and a laser beam having a second wavelength whose optical axes have been matched by the optical axis combining element are incident thereon, and the 0th-order light and ± 1st-order light of the laser light are A light-receiving element having three light-receiving surfaces for receiving light separately is provided, and the three light-receiving surfaces of the light-receiving elements are located on opposite sides of the main beam light-receiving surface for receiving the zero-order light and the main beam light-receiving surface. The main beam receiving surface is divided into four by two cross-shaped area dividing lines, and each of the pair of sub beam receiving surfaces is provided with the sub beam receiving surface. Dividing line into two in the direction orthogonal to the arrangement direction of the three light receiving surfaces, and the direction in which the light receiving spots of the laser light having the first wavelength and the laser light having the second wavelength are arranged in the three light receiving surfaces Niso Forming a first spot division line and a second spot division line for each division, forming a first area and a second area on the pair of sub-beam receiving surfaces by area division lines, respectively; For the laser light having the first wavelength, the 0-order light received on the main beam receiving surface and the primary light received on the first area of one of the sub-beam receiving surfaces and divided by the first spot dividing line. And a push-pull signal is detected using the primary light received by the second area of the other sub-beam receiving surface and divided by the first spot dividing line, and the laser light having the second wavelength is Zero-order light received by the main beam receiving surface, primary light received by the second area of one sub-beam receiving surface and divided by the second spot dividing line, and first-order light received by the other sub-beam receiving surface. Is obtained to detect the push-pull signal using the first-order light and split by the light receiving in the area second spot dividing line.
[0014]
According to another aspect of the present invention, there is provided an optical pickup and a disk drive device, wherein the first wavelength and the second wavelength corresponding to each of the two types of disk-shaped recording media are directed toward two different types of disk-shaped recording media. A light emitting element that emits a laser beam having a wavelength, a diffraction element that diffracts a laser beam having a first wavelength and a laser beam having a second wavelength, and a laser element that has the first wavelength and the second wavelength. A beam splitter that reflects or transmits the laser light having the first wavelength and the laser light having the second wavelength on the recording track of the disk-shaped recording medium. And an optical axis for matching the optical axes of the laser light having the first wavelength and the laser light having the second wavelength reflected by each disk-shaped recording medium And a laser beam having a first wavelength and a laser beam having a second wavelength whose optical axes are matched by the optical axis synthesizing element. And a light receiving element having three light receiving surfaces for receiving light separately. The three light receiving surfaces of the light receiving element are positioned opposite to each other with respect to the main beam light receiving surface for receiving the zero-order light and the main beam light receiving surface. The main beam receiving surface is divided into four by two cross-shaped area dividing lines, and the first wavelength is applied to one of the sub beam receiving surfaces. Forming a first spot division line for dividing the light receiving spot of the laser light having the light receiving spot in the direction in which the three light receiving surfaces are arranged, and forming the three light receiving spots of the laser light having the second wavelength on the other sub beam light receiving surface. Light reception A second spot division line is formed for dividing the laser beam having the first wavelength, and a zero-order light beam received by the main beam light receiving surface and a laser beam having the first wavelength are received by one of the sub beam light receiving surfaces. The push-pull signal is detected by using the primary light split by the first spot splitting line, and the laser light having the second wavelength is compared with the zero-order light received by the main beam receiving surface and the other. The push-pull signal is detected by using the primary light received by the sub-beam receiving surface and divided by the second spot dividing line.
[0015]
Therefore, in the optical pickup and the disk drive of the present invention, two types of laser beams having different wavelengths emitted from the same light emitting element are received by the light receiving surface of the same light receiving element.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of an optical pickup and a disk drive device according to the present invention will be described with reference to the accompanying drawings.
[0017]
The disk drive device 1 has required members and mechanisms arranged in an outer casing 2 (see FIG. 1).
[0018]
A chassis 3 is disposed in the outer casing 2, and a spindle motor (not shown) is attached to the chassis 3. The disk table 4 is fixed to the motor shaft of the spindle motor.
[0019]
An arrangement hole 3a is formed in the chassis 3, and the disk table 4 projects above the chassis 3 through the arrangement hole 3a.
[0020]
A lead screw 5 and guide shafts 6, 6 are arranged on the lower surface side of the chassis 3 in parallel. The optical pickup 7 is arranged in the arrangement hole 3 a of the chassis 3 so as to be movable in the radial direction of the disk-shaped recording medium 100 mounted on the disk table 4.
[0021]
The optical pickup 7 has a moving base 8, required optical elements (optical elements) provided on the moving base 8, and an objective lens driving device 9 supported on the moving base 8. Each is slidably supported by a guide shaft 6,6. When a nut member (not shown) provided on the moving base 8 is screwed into the lead screw 5 and the lead screw 5 is rotated by a feed motor (not shown) attached to the moving base 8, the nut member rotates in the rotation direction of the lead screw 5. The optical pickup 7 is guided by the guide shafts 6 and 6 and is moved in the radial direction of the disk-shaped recording medium 100 mounted on the disk table 4.
[0022]
The objective lens driving device 9 has a fixed part 10 and a movable part 12 movably supported by the fixed part 10 via a plurality of suspensions 11, 11,. Are held (see FIG. 1).
[0023]
Required optical elements are arranged on the moving base 8 (see FIG. 2).
[0024]
The optical elements include a light emitting element 14, a diffraction element 15, a beam splitter 16, a collimator lens 17, a rising mirror 18, an objective lens 13 provided in an objective lens driving device 9, an optical axis combining element 19, an adjustment lens 20, The light receiving element 21 and the like constitute an optical system of the disk drive device 1 by these optical elements.
[0025]
The light emitting element 14 has two light emitting points that emit laser lights having different wavelengths, and a laser light having a wavelength of 780 nm (first wavelength) is emitted from the first light emitting point, For example, a laser beam having a wavelength of 650 nm (second wavelength) is emitted from the light emitting point. When recording or reproducing an information signal on one disk-shaped recording medium 100, that is, the CD 100a, a laser beam having a wavelength of 780 nm is emitted from the first light emitting point, and the other disk-shaped recording medium 100, that is, When recording or reproducing an information signal with respect to the DVD 100b, a laser beam having a wavelength of 650 nm is emitted from the second light emitting point.
[0026]
The first light emitting point and the second light emitting point of the light emitting element 14 are arranged at a predetermined interval, for example, an interval of 30 μm to 300 μm, and the laser light having the second wavelength is used for the above optical system. Although coincident on the optical axis, the laser light having the first wavelength is shifted from the optical axis of the optical system.
[0027]
As the diffraction element 15, for example, a grating is used, and one surface is formed as a diffraction surface 15a having a plurality of grooves. The diffraction element 15 has a function of diffracting incident laser light to generate 0th-order light and ± 1st-order light. Since the size of the diffraction angle in the diffraction element 15 depends on the wavelength of the incident laser light, the diffraction angle θ1 when the laser light having the wavelength of 780 nm is incident is such that the laser light having the wavelength of 650 nm is incident. It is larger than the diffraction angle θ2 when the diffraction is performed.
[0028]
The beam splitter 16 is, for example, a reflection type, and reflects the laser light emitted from the light emitting element 14 on the separation surface 16a to guide it to the collimator lens 17, and returns the laser light reflected on the disk-shaped recording medium 100. And a function of guiding the light to the optical axis combining element 19.
[0029]
The collimator lens 17 has a function of converting the light beam of the incident laser light into a parallel light beam, and the rising mirror 18 has a function of reflecting the laser light and guiding it to the objective lens 13 or the collimator lens 17. Reference numeral 13 has a function of condensing the incident laser light on a recording track of the disc-shaped recording medium 100.
[0030]
The optical axis synthesizing element 19 has a function of correcting the optical axis direction of the laser light having the first wavelength shifted from the optical axis of the optical system and causing the laser light to enter from a predetermined position and direction of the light receiving element 21. .
[0031]
The adjustment lens 20 is a lens for adjusting the magnification of the laser beam.
[0032]
The light receiving element 21 has a main beam light receiving surface 22 and sub beam light receiving surfaces 23 and 24 (see FIG. 3). The main beam receiving surface 22 and the sub beam receiving surfaces 23 and 24 are respectively arranged at a fixed interval, and the sub beam receiving surfaces 23 and 24 are located on opposite sides of the main beam receiving surface 22.
[0033]
The main beam receiving surface 22 is a region for receiving the 0th order light, the sub beam receiving surface 23 is a region for receiving the + 1st order light, and the sub beam receiving surface 24 is a region for receiving the −1st order light. Therefore, when each laser light is emitted from the light emitting element 14, the main beam receiving surface 22 receives the light receiving spot Sma of the zero-order light of the laser light having the wavelength of 780 nm or the zero-order light of the laser light having the wavelength of 650 nm. Are formed on the sub-beam receiving surfaces 23 and 24, respectively, of the light receiving spots Ssa and Ssa of the ± 1st order light of the laser beam having the wavelength of 780 nm or ± 1st order light of the laser beam having the wavelength of 650 nm. Light receiving spots Ssb and Ssb are formed (see FIG. 3).
[0034]
The main beam receiving surface 22 is equally divided into four square areas by two cross-shaped area dividing lines 22a and 22b, and these four areas are area a, area b, area c, and area, respectively. d. Therefore, the light receiving spots Sma and Smb of the zero-order light of each laser beam are divided into four by the area dividing lines 22a and 22b, respectively.
[0035]
On the sub-beam light receiving surface 23, the first spot dividing line 23a and the second spot separating line 23a are separated from each other in a direction in which the light receiving surfaces 22, 23, and 24 are arranged (hereinafter, the direction in which the light receiving surfaces are arranged is simply referred to as an "arrangement direction"). A spot dividing line 23b is formed. The sub-beam receiving surface 23 is divided into three areas by a first spot dividing line 23a and a second spot dividing line 23b, and these three areas are respectively area e, area f, and area f from the side closer to the main beam receiving surface 22. Area g is set.
[0036]
The first spot dividing line 23a is formed at a position farther from the main beam receiving surface 22 than the second spot dividing line 23b. The first spot dividing line 23a divides the light receiving spot Ssa of the +1 order light of the laser beam having the first wavelength into two (see FIG. 3B), and the second spot dividing line 23b It has a function of dividing the light receiving spot Ssb of the +1 order light of the laser light having the wavelength of 2 into two (see FIG. 3C).
[0037]
On the sub beam receiving surface 24, a first spot dividing line 24a and a second spot dividing line 24b are formed apart from each other in the arrangement direction. The sub-beam receiving surface 24 is divided into three areas by a first spot dividing line 24a and a second spot dividing line 24b, and these three areas are areas h, i, and i, respectively, from the side closer to the main beam receiving surface 22. The area j is set.
[0038]
The first spot division line 24a is formed at a position farther from the main beam receiving surface 22 than the second spot division line 24b. The first spot dividing line 24a divides the light receiving spot Ssa of the primary light of the laser beam having the first wavelength into two (see FIG. 3B), and the second spot dividing line 24b It has a function of dividing the light receiving spot Ssb of the −1st-order light of the laser light having the second wavelength into two (see FIG. 3C).
[0039]
In the optical system configured as described above, when the laser light having the first wavelength is emitted from the light emitting element 14, the emitted laser light is diffracted at the diffraction angle θ1 by the diffractive element 15 and becomes zero-order light. ± 1st order light is generated. The laser light is reflected by the separation surface 16 a of the beam splitter 16, converted into a parallel light beam by the collimator lens 17, raised by the raising mirror 18, and recorded on the CD 100 a mounted on the disk table 4 via the objective lens 13. Is irradiated. The laser light applied to the recording surface of the CD 100a is reflected by the recording surface and returns as a return light to the beam splitter 16 via the objective lens 13, the rising mirror 18 and the collimator lens 17 again. The return light that has entered the beam splitter 16 is transmitted through the separation surface 16 a of the beam splitter 16, the optical axis direction is corrected by the optical axis combining element 19, and is incident on the light receiving element 21 via the adjustment lens 20.
[0040]
With respect to the laser light having the first wavelength incident on the light receiving element 21, the diffracted zero-order light is received by the main beam receiving surface 22, and the ± first-order lights are received by the sub-beam receiving surfaces 23 and 24, respectively.
[0041]
In the optical pickup 7, the center of the spot of the zero-order light Sma of the laser light having the first wavelength substantially coincides with the intersection of the area dividing lines 22 a and 22 b of the main beam receiving surface 22, and the first Diffraction by the diffractive element 15 so that the center of each spot of the ± first-order light beams Ssa and Ssa of the laser beam having the wavelengths substantially coincides with the centers of the first spot division lines 23a and 24a of the sub-beam receiving surfaces 23 and 24, respectively. The angle θ1 and the positions of the light receiving surfaces 22, 23, 24 are set.
[0042]
On the other hand, when the laser light having the second wavelength is emitted from the light emitting element 14, the emitted laser light is diffracted by the diffractive element 15 at the diffraction angle θ2 smaller than the diffraction angle θ1, and the zero-order light and the ± first-order light are emitted. Is generated. The laser light is reflected by the separation surface 16 a of the beam splitter 16, converted into a parallel light beam by the collimator lens 17, raised by the rising mirror 18, and recorded on the DVD 100 b mounted on the disk table 4 via the objective lens 13. Is irradiated. The laser beam applied to the recording surface of the DVD 100b is reflected by the recording surface and returns to the beam splitter 16 via the objective lens 13, the rising mirror 18 and the collimator lens 17 as return light. The return light that has entered the beam splitter 16 is transmitted through the separation surface 16a of the beam splitter 16, and is sequentially incident on the light receiving element 21 via the optical axis combining element 19 and the adjustment lens 20.
[0043]
With respect to the laser light having the second wavelength incident on the light receiving element 21, the diffracted 0th-order light is received by the main beam receiving surface 22 and ± 1st-order light is received by the sub-beam receiving surfaces 23 and 24, respectively.
[0044]
In the optical pickup 7, the center of the spot of the zero-order light Smb of the laser light having the second wavelength substantially coincides with the intersection of the area dividing lines 22 a and 22 b of the main beam receiving surface 22, and the second Diffraction by the diffractive element 15 such that the center of each spot of the ± 1st order light Ssb, Ssb of the laser light having the wavelength of approximately the same as the center of the second spot dividing lines 23b, 24b of the sub beam receiving surfaces 23, 24 respectively. The angle θ2 and the positions of the light receiving surfaces 22, 23, and 24 are set.
[0045]
When the return light of the laser light having the first wavelength or the return light of the laser light having the second wavelength is incident on the light receiving element 21, the return light is based on the zero-order light Sma and Smb received by the main beam receiving surface 22. The recording or reading of the information signal on the CD 100a and the DVD 100b is performed. At the same time, a focusing error signal is detected based on the zero-order lights Sma and Smb received on the main beam receiving surface 22, and the zero-order light Sma received on the main beam receiving surface 22 and the sub-beam receiving surfaces 23 and 24. , Smb, and ± first-order lights Ssa, Ssa, Ssb, and Ssb, the tracking error signals are detected. Based on these detection results, the movable unit 12 of the objective lens driving device 9 The displacement and the focusing adjustment and the tracking adjustment are performed.
[0046]
When the 0th-order light or ± 1st-order light is received by the main beam receiving surface 22 and the sub beam receiving surfaces 23 and 24, each of the areas a, b, c, d, e, f, g, h, i, j Each detection current is generated by photoelectric conversion, and each of these detection currents is converted into a voltage and output as detection signals a, b, c, d, e, f, g, h, i, and j.
[0047]
In the optical pickup 7, an astigmatism method is used to detect a focusing error signal, and the focusing error signal FE for the CD 100a and the DVD 100b is calculated by an arithmetic circuit (not shown) as follows.
FE = (a + c)-(b + d) (1)
Is generated based on the calculation.
[0048]
The differential push-pull method is used to detect the tracking error signal. The tracking error signal TEa for the CD 100a is calculated by the arithmetic circuit according to the following formula.
TEa = (a + d)-(b + c) -K1 {g- (f + e) + (h + i) -j} (2)
Is generated based on the calculation. Here, K1 is a proportional constant.
[0049]
The tracking error signal TEb for the DVD 100b is calculated by the following equation using an arithmetic circuit.
TEb = (a + d)-(b + c) -K2 {(g + f) -e + h- (i + j)} (3)
Is generated based on the calculation. Here, K2 is a proportional constant.
[0050]
As described above, in the optical pickup 7, the light receiving spots Ssa, Ssa, Ssb, and Ssb of the ± primary lights of the respective laser lights having different wavelengths are respectively divided on the sub-beam receiving surfaces 23 and 24 of the light receiving element 21. Since the first spot dividing lines 23a and 24a and the second spot dividing lines 23b and 24b are formed, a push-pull signal can be detected for each of the laser beams having different wavelengths.
[0051]
Therefore, a common light-emitting element 14, diffraction element 15, beam splitter 16 and light-receiving element 21 can be used for laser beams having different wavelengths. The size of the pickup 7 can be reduced.
[0052]
In addition, since three types of diffracted light, ie, 0-order light and ± 1st-order light, can be used for two types of laser light having different wavelengths, various types of CDs (CD-ROM, CD-R, CD-RW) can be used. Etc.) and DVDs (DVD video, DVD-ROM, DVD-R, DVD-RAM, etc.) can be recorded and reproduced, and the types of usable disc-shaped recording media 100 can be increased. 7 can be improved.
[0053]
Next, a first modification of the light receiving surface will be described (see FIG. 4). The modified example described below is different from the above-described main beam receiving surface 22 and sub beam receiving surfaces 23 and 24 only in that a new different dividing line is formed on the sub beam receiving surface for receiving ± primary light. Therefore, only the different portions as compared with the main beam receiving surface 22 and the sub beam receiving surfaces 23 and 24 will be described in detail, and the other portions will be the same as those in the main beam receiving surface 22 and the sub beam receiving surfaces 23 and 24. The same reference numerals are given to the same reference numerals as in the above, and the description is omitted.
[0054]
The main beam receiving surface 22 is a region for receiving the 0th order light, the sub beam receiving surface 23A is a region for receiving the + 1st order light, and the sub beam receiving surface 24A is a region for receiving the −1st order light.
[0055]
The sub-beam receiving surface 23A is arranged so that the sub-beam receiving surface 23A is perpendicular to the direction in which the light receiving surfaces 22, 23A and 24A are arranged (hereinafter, the direction perpendicular to the direction in which the light receiving surfaces are arranged is simply referred to as the "orthogonal direction"). An area dividing line 23c for equally dividing is formed. The sub-beam receiving surface 23A is divided into six areas by a first spot dividing line 23a, a second spot dividing line 23b, and an area dividing line 23c. As shown in FIG. Area f, area g, area k, area 1, and area m. On the sub-beam receiving surface 23A, a first area 23A1 is constituted by the areas e, f, and g, and a second area 23A2 is constituted by the areas k, l, and m.
[0056]
An area dividing line 24c that divides the sub-beam receiving surface 24A equally in the orthogonal direction is formed on the sub-beam receiving surface 24A. The sub beam receiving surface 24A is divided into six areas by a first spot dividing line 24a, a second spot dividing line 24b, and an area dividing line 24c. As shown in FIG. Area i, area j, area n, area o, and area p. On the sub-beam receiving surface 24A, a first area 24A1 is constituted by the areas h, i and j, and a second area 24A2 is constituted by the areas n, o and p.
[0057]
When the 0th order light or the ± 1st order light is received by the main beam receiving surface 22 and the sub beam receiving surfaces 23A and 24A, each area a, b, c, d, e, f, g, h, i, j, k , L, m, n, o, p are photoelectrically converted to generate respective detection currents, and these respective detection currents are converted into voltages, and the detection signals a, b, c, d, e, f, g, Output as h, i, j, k, l, m, n, o, p.
[0058]
An astigmatism method is used to detect a focusing error signal, and the focusing error signal FE for the CD 100a and the DVD 100b is calculated by the arithmetic circuit as
FE = (a + c)-(b + d) (4)
Is generated based on the calculation.
[0059]
In the case of the main beam light receiving surface 22 and the sub beam light receiving surfaces 23A and 24A, a differential astigmatism method can be used to detect a focusing error signal.
[0060]
In the astigmatism method, there is a problem that a push-pull signal leaks into a focusing error signal. In particular, in a land group type disk-shaped recording medium such as a DVD-RAM, the leak problem tends to occur.
[0061]
On the other hand, the differential astigmatism method uses the fact that the phases of the push-pull signal of the 0th-order light and the push-pull signal of the ± 1st-order light are opposite to each other, and adds and cancels both push-pull signals. This prevents the push-pull signal from leaking into the focusing error signal and detects the focusing error signal.
[0062]
Therefore, it is preferable to use the differential astigmatism method particularly for a land group type disk-shaped recording medium such as a DVD-RAM in which the problem of leakage is likely to occur.
[0063]
When the differential astigmatism method is used to detect the focusing error signal, for example, the focusing error signal FE ′ for the DVD 100b is calculated by the arithmetic circuit using the following equation.
FE '= (a + c)-(b + d) + K3 [{(g + f) + m}-{(k + 1) + e} + {(h + i) + p}-{(n + o) + j}] (5)
Is generated based on the calculation. Here, K3 is a proportional constant.
[0064]
The differential push-pull method is used to detect the tracking error signal. The tracking error signal TEa for the CD 100a is calculated by the arithmetic circuit according to the following formula.
TEa = (a + d)-(b + c) -K4 {(g + k)-(f + l + e + m) + (h + n + i + o)-(j + p)} (6)
Is generated based on the calculation. Here, K4 is a proportionality constant.
[0065]
The tracking error signal TEb for the DVD 100b is calculated by the following equation using an arithmetic circuit.
TEb = (a + d)-(b + c) -K5 {(g + f + k + 1)-(e + m) + (h + n)-(i + j + o + p)} (7)
Is generated based on the calculation. Here, K5 is a proportional constant.
[0066]
As described above, when the main beam light receiving surface 22 and the sub beam light receiving surfaces 23A and 24A are used, the light receiving spot Ssa of the ± primary light of each laser beam having a different wavelength is provided on the sub beam light receiving surfaces 23A and 24A. , Ssa, Ssb, and the first spot dividing lines 23a and 24a and the second spot dividing lines 23b and 24b respectively dividing the Ssb, so that a push-pull signal can be detected for each of the laser beams having different wavelengths. Can be.
[0067]
Therefore, a common light-emitting element 14, diffraction element 15, beam splitter 16 and light-receiving element 21 can be used for laser beams having different wavelengths. The size of the pickup 7 can be reduced.
[0068]
In addition, since three types of diffracted light, ie, 0-order light and ± 1st-order light, can be used for two types of laser light having different wavelengths, various types of CDs (CD-ROM, CD-R, CD-RW) can be used. Etc.) and DVDs (DVD video, DVD-ROM, DVD-R, DVD-RAM, etc.) can be recorded and reproduced, and the types of usable disc-shaped recording media 100 can be increased. 7 can be improved.
[0069]
Furthermore, since the area dividing lines 23c and 24c are formed on the sub-beam receiving surfaces 23A and 24A, respectively, the differential astigmatism method can be used for detecting the focusing error signal, and the accurate focusing error signal is detected. be able to.
[0070]
Next, a second modification of the light receiving surface will be described (see FIG. 5). The modification shown below is different from the above-mentioned main beam receiving surface 22 and sub beam receiving surfaces 23 and 24 in that the division position of the dividing line of the sub beam receiving surface for receiving ± primary light is different, and that another new The only difference is that the dividing line is formed. Therefore, only the different portions from the main beam receiving surface 22 and the sub beam receiving surfaces 23 and 24 will be described in detail, and the other portions will be described. The same reference numerals are given to the same parts on the sub-beam receiving surfaces 23 and 24, and the description is omitted.
[0071]
The main beam receiving surface 22 is a region for receiving the 0th order light, the sub beam receiving surface 23B is a region for receiving the + 1st order light, and the sub beam receiving surface 24B is a region for receiving the −1st order light.
[0072]
An area dividing line 23d that divides the sub-beam receiving surface 23B equally in the orthogonal direction is formed on the sub-beam receiving surface 23B. The sub beam receiving surface 23B is divided into a first area 23B1 and a second area 23B2 by an area dividing line 23d.
[0073]
A first spot dividing line 23e and a second spot dividing line 23f are formed on the sub beam receiving surface 23B. The first spot dividing line 23e is formed in the first area 23B1, the second spot dividing line 23f is formed in the second area 23B2, and the second spot dividing line 23f is formed from the first spot dividing line 23e. It is formed at a position closer to the main beam receiving surface 22 side in the arrangement direction.
[0074]
The sub-beam receiving surface 23B is divided into four areas by an area dividing line 23d, a first spot dividing line 23e, and a second spot dividing line 23f. As shown in FIG. f, area g, and area h.
[0075]
An area dividing line 24d is formed on the sub-beam receiving surface 24B to equally divide the sub-beam receiving surface 24B in the orthogonal direction. The sub beam receiving surface 24B is divided into a first area 24B1 and a second area 24B2 by an area dividing line 24d.
[0076]
A first spot dividing line 24e and a second spot dividing line 24f are formed on the sub beam receiving surface 24B. The first spot dividing line 24e is formed in the second area 24B2, the second spot dividing line 24f is formed in the first area 24B1, and the second spot dividing line 24f is formed from the first spot dividing line 24e. It is formed at a position closer to the main beam receiving surface 22 side in the arrangement direction.
[0077]
The sub beam receiving surface 24B is divided into four areas by an area dividing line 24d, a first spot dividing line 24e, and a second spot dividing line 24f. As shown in FIG. j, area k, and area l.
[0078]
When the 0th-order light or the ± 1st-order light is received by the main beam receiving surface 22 and the sub beam receiving surfaces 23B and 24B, each area a, b, c, d, e, f, g, h, i, j, k , L, photoelectric conversion is performed to generate respective detection currents, and these respective detection currents are converted into voltages, and the detection signals a, b, c, d, e, f, g, h, i, j, k, Output as l.
[0079]
In the case of the main beam light receiving surface 22 and the sub beam light receiving surfaces 23B and 24B, when the ± primary light is used in the detection of each error signal, the first area 23B1 and the second area 24B2 of the ± primary light are used. Alternatively, only the portions that are received by the second area 23B2 and the first area 24B1 are used. For example, for the laser light having the first wavelength, only the portion received in the first area 23B1 and the second area 24B2 is used, and for the laser light having the second wavelength, the second area 23B2 is used. And only the portion that is received by the second area 24B1 is used. Conversely, for the laser light having the first wavelength, only the portions received in the second area 23B2 and the first area 24B1 are used, and for the laser light having the second wavelength, the first area 23B1 Only the part that receives light in the second area 24B2 may be used.
[0080]
An astigmatism method is used to detect a focusing error signal, and the focusing error signal FE for the CD 100a and the DVD 100b is calculated by the arithmetic circuit as
FE = (a + c)-(b + d) (8)
Is generated based on the calculation.
[0081]
In the case of the main beam light receiving surface 22 and the sub beam light receiving surfaces 23B and 24B, a differential astigmatism method can be used to detect a focusing error signal.
[0082]
When the differential astigmatism method is used to detect the focusing error signal, for example, the focusing error signal FE ′ for the DVD 100b is calculated by the arithmetic circuit using the following equation.
FE '= (a + c)-(b + d) + K6 {(i + g)-(j + h)} (9)
Is generated based on the calculation. Here, K6 is a proportional constant.
[0083]
The differential push-pull method is used to detect the tracking error signal. The tracking error signal TEa for the CD 100a is calculated by the arithmetic circuit according to the following formula.
TEa = (a + d)-(b + c) -K7 {(e + 1)-(f + k)} (10)
Is generated based on the calculation. Here, K7 is a proportional constant.
[0084]
The tracking error signal TEb for the DVD 100b is calculated by the following equation using an arithmetic circuit.
TEb = (a + d)-(b + c) -K8 {(i + h)-(j + g)} (11)
Is generated based on the calculation. Here, K8 is a proportional constant.
[0085]
As described above, when the main beam light receiving surface 22 and the sub beam light receiving surfaces 23B and 24B are used, the light receiving spot Ssa of the ± primary light of each laser beam having a different wavelength is provided on the sub beam light receiving surfaces 23B and 24B. , Ssa, Ssb, and Ssb, the first spot division lines 23e and 24e and the second spot division lines 23f and 24f are formed, so that a push-pull signal can be detected for each of laser beams having different wavelengths. Can be.
[0086]
Therefore, a common light-emitting element 14, diffraction element 15, beam splitter 16 and light-receiving element 21 can be used for laser beams having different wavelengths. The size of the pickup 7 can be reduced.
[0087]
In addition, since three types of diffracted light, ie, 0-order light and ± 1st-order light, can be used for two types of laser light having different wavelengths, various types of CDs (CD-ROM, CD-R, CD-RW) can be used. Etc.) and DVDs (DVD video, DVD-ROM, DVD-R, DVD-RAM, etc.) can be recorded and reproduced, and the types of usable disc-shaped recording media 100 can be increased. 7 can be improved.
[0088]
Further, since the area dividing lines 23d and 24d are formed on the sub-beam receiving surfaces 23B and 24B, respectively, the differential astigmatism method can be used for detecting the focusing error signal, and the accurate focusing error signal is detected. be able to.
[0089]
In addition, in the case of the main beam light receiving surface 22 and the sub beam light receiving surfaces 23B and 24B, the detection of the error signal is performed by using only the portion of one side of the sub beam light receiving surfaces 23B and 24B of ± 1 order light. Therefore, the number of areas is small and the light receiving surface can be simplified and the signal detection can be simplified.
[0090]
Next, a third modification of the light receiving surface will be described (see FIG. 6). The modification shown below is different from the main beam receiving surface 22 and the sub-beam receiving surfaces 23 and 24 only in that only one division line is formed on the sub-beam receiving surface for receiving ± 1 order light. Because of the differences, only the different portions compared to the main beam receiving surface 22 and the sub beam receiving surfaces 23 and 24 will be described in detail, and the other portions will be the same in the main beam receiving surface 22 and the sub beam receiving surfaces 23 and 24. The same reference numerals are given to the parts and the description is omitted.
[0091]
The main beam receiving surface 22 is a region for receiving the 0th order light, the sub beam receiving surface 23C is a region for receiving the + 1st order light, and the sub beam receiving surface 24C is a region for receiving the −1st order light.
[0092]
A spot division line 23g that divides the sub-beam receiving surface 23C in the arrangement direction is formed on the sub-beam receiving surface 23C. The sub beam receiving surface 23C is divided into an area e and an area f by the spot dividing line 23g. The spot division line 23g has a function of dividing the reception spot Ssb of the + 1st-order light of the laser beam having the second wavelength into two (see FIG. 6C).
[0093]
A spot dividing line 24g that divides the sub-beam receiving surface 24C in the arrangement direction is formed on the sub-beam receiving surface 24C. The sub beam receiving surface 24C is divided into an area g and an area h by the spot dividing line 24g. The spot dividing line 24g has a function of dividing the receiving spot Ssa of the primary light of the laser beam having the first wavelength into two (see FIG. 6B).
[0094]
When the 0th-order light or ± 1st-order light is received by the main beam receiving surface 22 and the sub beam receiving surfaces 23C and 24C, they are photoelectrically converted for each of the areas a, b, c, d, e, f, g and h. Each detection current is generated, and these detection currents are converted into voltages and output as detection signals a, b, c, d, e, f, g, and h.
[0095]
In the case of the main beam light receiving surface 22 and the sub beam light receiving surfaces 23C and 24C, when ± 1st order light is used in the detection of each error signal, only one of the + 1st order light and the −1st order light is used. You. For example, for the laser light having the first wavelength, only the -1 order light is used, and for the laser light having the second wavelength, only the +1 order light is used. Conversely, for the laser light having the first wavelength, only the +1 order light may be used, and for the laser light having the second wavelength, only the −1 order light may be used.
[0096]
An astigmatism method is used to detect a focusing error signal, and the focusing error signal FE for the CD 100a and the DVD 100b is calculated by the arithmetic circuit as
FE = (a + c)-(b + d) (12)
Is generated based on the calculation.
[0097]
The differential push-pull method is used to detect the tracking error signal. The tracking error signal TEa for the CD 100a is calculated by the arithmetic circuit according to the following formula.
TEa = (a + d)-(b + c) -K9 (gh) (13)
Is generated based on the calculation. Here, K9 is a proportional constant.
[0098]
The tracking error signal TEb for the DVD 100b is calculated by the following equation using an arithmetic circuit.
TEb = (a + d)-(b + c) -K10 (fe) (14)
Is generated based on the calculation. Here, K10 is a proportional constant.
[0099]
As described above, when the main beam light receiving surface 22 and the sub beam light receiving surfaces 23C and 24C are used, the light receiving spot Ssb of the ± primary light of each laser beam having a different wavelength is provided on the sub beam light receiving surfaces 23C and 24C. , And Ssa, the spot division lines 23g and 24g are formed, so that a push-pull signal can be detected for each of the laser beams having different wavelengths.
[0100]
Therefore, a common light-emitting element 14, diffraction element 15, beam splitter 16 and light-receiving element 21 can be used for laser beams having different wavelengths. The size of the pickup 7 can be reduced.
[0101]
In addition, since three types of diffracted light, ie, 0-order light and ± 1st-order light, can be used for two types of laser light having different wavelengths, various types of CDs (CD-ROM, CD-R, CD-RW) can be used. Etc.) and DVDs (DVD video, DVD-ROM, DVD-R, DVD-RAM, etc.) can be recorded and reproduced, and the types of usable disc-shaped recording media 100 can be increased. 7 can be improved.
[0102]
Further, in the case of the main beam light receiving surface 22 and the sub beam light receiving surfaces 23C and 24C, the error signal is detected by using only the + 1st order light or the -1st order light. And signal detection can be simplified.
[0103]
Next, a fourth modification of the light receiving surface will be described (see FIG. 7). The following modified example is different from the main beam receiving surface 22 and the sub beam receiving surfaces 23C and 24C according to the third modified example described above in that another new dividing line is added to the sub beam receiving surface for receiving ± primary light. Is different only in that the main beam receiving surface 22 and the sub beam receiving surfaces 23C and 24C are different from each other. The same reference numerals are given to the same parts on the light receiving surfaces 23C and 24C, and the description is omitted.
[0104]
The main beam receiving surface 22 is a region for receiving the 0th order light, the sub beam receiving surface 23D is a region for receiving the + 1st order light, and the sub beam receiving surface 24D is a region for receiving the −1st order light.
[0105]
An area dividing line 23h that divides the sub-beam receiving surface 23D equally in the orthogonal direction is formed on the sub-beam receiving surface 23D. The sub beam receiving surface 23D is divided into a first area 23D1 and a second area 23D2 by an area dividing line 23h.
[0106]
The sub-beam receiving surface 23D is divided into four areas by a spot dividing line 23g and an area dividing line 23h. As shown in FIG. 7, these four areas are an area e, an area f, an area g, and an area h, respectively. .
[0107]
An area dividing line 24h that divides the sub-beam receiving surface 24D equally in the orthogonal direction is formed on the sub-beam receiving surface 24D. The sub beam receiving surface 24D is divided into a first area 24D1 and a second area 24D2 by an area dividing line 24h.
[0108]
The sub-beam receiving surface 24D is divided into four areas by a spot dividing line 24g and an area dividing line 24h. As shown in FIG. 7, these four areas are an area i, an area j, an area k, and an area 1, respectively. .
[0109]
When the 0th-order light or the ± 1st-order light is received by the main beam receiving surface 22 and the sub beam receiving surfaces 23D and 24D, each area a, b, c, d, e, f, g, h, i, j, k , L, photoelectric conversion is performed to generate respective detection currents, and these respective detection currents are converted into voltages, and the detection signals a, b, c, d, e, f, g, h, i, j, k, Output as l.
[0110]
In the case of the main beam light receiving surface 22 and the sub beam light receiving surfaces 23D and 24D, when ± 1st order light is used in the detection of each error signal, only one of the + 1st order light and the −1st order light is used. You. For example, for the laser light having the first wavelength, only the -1 order light is used, and for the laser light having the second wavelength, only the +1 order light is used. Conversely, for the laser light having the first wavelength, only the +1 order light may be used, and for the laser light having the second wavelength, only the −1 order light may be used.
[0111]
An astigmatism method is used to detect a focusing error signal, and the focusing error signal FE for the CD 100a and the DVD 100b is calculated by the arithmetic circuit as
FE = (a + c)-(b + d) (15)
Is generated based on the calculation.
[0112]
In the case of the main beam light receiving surface 22 and the sub beam light receiving surfaces 23D and 24D, a differential astigmatism method can be used to detect a focusing error signal.
[0113]
When the differential astigmatism method is used to detect the focusing error signal, for example, the focusing error signal FE ′ for the DVD 100b is calculated by the arithmetic circuit using the following equation.
FE '= (a + c)-(b + d) + K11 {(f + h)-(e + g)} (16)
Is generated based on the calculation. Here, K11 is a proportionality constant.
[0114]
The differential push-pull method is used to detect the tracking error signal. The tracking error signal TEa for the CD 100a is calculated by the arithmetic circuit according to the following formula.
TEa = (a + d)-(b + c) -K12 {(i + 1)-(j + k)} (17)
Is generated based on the calculation. Here, K12 is a proportionality constant.
[0115]
The tracking error signal TEb for the DVD 100b is calculated by the following equation using an arithmetic circuit.
TEb = (a + d)-(b + c) -K13 {(f + g)-(e + h)} (18)
Is generated based on the calculation. Here, K13 is a proportional constant.
[0116]
As described above, when the main beam light receiving surface 22 and the sub beam light receiving surfaces 23D and 24D are used, the light receiving spot Ssb of the ± primary light of each laser beam having a different wavelength is provided on the sub beam light receiving surfaces 23D and 24D. , Ssa are formed, so that the push-pull signal can be detected for each of the laser beams having different wavelengths.
[0117]
Therefore, a common light-emitting element 14, diffraction element 15, beam splitter 16 and light-receiving element 21 can be used for laser beams having different wavelengths. The size of the pickup 7 can be reduced.
[0118]
In addition, since three types of diffracted light, ie, 0-order light and ± 1st-order light, can be used for two types of laser light having different wavelengths, various types of CDs (CD-ROM, CD-R, CD-RW) can be used. Etc.) and DVDs (DVD video, DVD-ROM, DVD-R, DVD-RAM, etc.) can be recorded and reproduced, and the types of usable disc-shaped recording media 100 can be increased. 7 can be improved.
[0119]
Furthermore, since the area dividing lines 23h and 24h are formed on the sub beam receiving surfaces 23D and 24D, respectively, the differential astigmatism method can be used for detecting the focusing error signal, and the accurate focusing error signal is detected. be able to.
[0120]
In addition, in the case of the main beam light receiving surface 22 and the sub beam light receiving surfaces 23D and 24D, the error signal is detected using only the + 1st-order light or the -1st-order light. The surface can be simplified and the signal detection can be simplified.
[0121]
In the above description, the wavelength of 780 nm is the first wavelength and the wavelength of 650 nm is the second wavelength. However, the wavelength of 650 nm may be the first wavelength and the wavelength of 780 nm may be the second wavelength.
[0122]
In the above description, the example in which the first wavelength is 780 nm and the second wavelength is 650 nm has been described, but the first wavelength and the second wavelength are not limited to 780 nm and 650 nm, respectively. The present invention can be applied to a case where laser beams having two types of arbitrary wavelengths having different wavelength lengths are used.
[0123]
The specific shapes and structures of the respective parts shown in the above-described embodiments are merely examples of the specific embodiments of the present invention, and the technical scope of the present invention is limited by these examples. It must not be interpreted in a tentative way.
[0124]
【The invention's effect】
As is apparent from the above description, according to the first aspect of the present invention, the first light receiving spots of the ± primary light of each laser light having different wavelengths are divided on the sub-beam light receiving surface of the light receiving element. Since the spot division line and the second spot division line are formed, a push-pull signal can be detected for each of the laser beams having different wavelengths. An element, a beam splitter, and a light receiving element can be used, and the number of components can be reduced, and the size of the optical pickup can be reduced by saving the space for each optical element.
[0125]
In addition, since three types of diffracted light, ie, 0th-order light and ± 1st-order light, can be used for two types of laser light having different wavelengths, information signals are recorded and reproduced on and from various disc-shaped recording media. Thus, the types of disk-shaped recording media that can be used are increased, and the performance of the optical pickup can be improved.
[0126]
According to the second aspect of the present invention, the differential astigmatism method can be used for detecting the focusing error signal, and the accurate focusing error signal can be detected.
[0127]
According to the third aspect of the present invention, the first spot dividing line and the second spot dividing line for dividing the light receiving spots of the ± primary lights of the respective laser beams having different wavelengths on the sub-beam receiving surface of the light receiving element. Since a push-pull signal can be detected for each of the laser beams having different wavelengths, a common light emitting element, diffraction element, beam splitter and light receiving element can be used for laser lights having different wavelengths. Thus, the number of components can be reduced, and the size of the optical pickup can be reduced by saving the space for each optical element.
[0128]
In addition, since three types of diffracted light, ie, 0th-order light and ± 1st-order light, can be used for two types of laser light having different wavelengths, information signals are recorded and reproduced on and from various disc-shaped recording media. Thus, the types of disk-shaped recording media that can be used are increased, and the performance of the optical pickup can be improved.
[0129]
Further, since the error signal is detected by using only the part received on one side of the sub-beam light receiving surface of the ± 1st order light, the number of areas is small, the light receiving surface is simplified, and the signal detection is simplified. be able to.
[0130]
In addition, the differential astigmatism method can be used for detecting the focusing error signal, and the accurate focusing error signal can be detected.
[0131]
According to the fourth aspect of the present invention, the first spot dividing line and the second spot dividing line for dividing the light receiving spots of the ± primary lights of the laser beams having different wavelengths on the sub-beam receiving surface of the light receiving element. Since a push-pull signal can be detected for each of the laser beams having different wavelengths, a common light emitting element, diffraction element, beam splitter and light receiving element can be used for laser lights having different wavelengths. Thus, the number of components can be reduced, and the size of the optical pickup can be reduced by saving the space for each optical element.
[0132]
In addition, since three types of diffracted light, ie, 0th-order light and ± 1st-order light, can be used for two types of laser light having different wavelengths, information signals are recorded and reproduced on and from various disc-shaped recording media. Thus, the types of disk-shaped recording media that can be used are increased, and the performance of the optical pickup can be improved.
[0133]
Further, since the error signal is detected by using only the part received on one side of the sub-beam light receiving surface of the ± 1st order light, the number of areas is small, the light receiving surface is simplified, and the signal detection is simplified. be able to.
[0134]
According to the fifth aspect of the present invention, the differential astigmatism method can be used for detecting the focusing error signal, and the accurate focusing error signal can be detected.
[0135]
According to the invention described in claim 6, the first spot division line and the second spot division line for dividing the light receiving spots of ± primary light of each laser light having different wavelengths on the sub-beam receiving surface of the light receiving element. Since a push-pull signal can be detected for each of the laser beams having different wavelengths, a common light emitting element, diffraction element, beam splitter and light receiving element can be used for laser lights having different wavelengths. Thus, the number of parts can be reduced, and the size of the disk drive device can be reduced by saving the space for each optical element.
[0136]
In addition, since three types of diffracted light, ie, 0th-order light and ± 1st-order light, can be used for two types of laser light having different wavelengths, information signals are recorded and reproduced on and from various disc-shaped recording media. Thus, the types of disk-shaped recording media that can be used are increased, and the performance of the disk drive device can be improved.
[0137]
According to the seventh aspect of the present invention, the differential astigmatism method can be used for detecting the focusing error signal, and the accurate focusing error signal can be detected.
[0138]
According to the invention described in claim 8, the first spot division line and the second spot division line for dividing the light receiving spots of the ± primary lights of the respective laser beams having different wavelengths on the sub-beam receiving surface of the light receiving element. Since a push-pull signal can be detected for each of laser beams having different wavelengths, a common light emitting element, diffraction element, beam splitter and light receiving element can be used for laser lights having different wavelengths. Thus, the number of components can be reduced, and the size of the disk drive device can be reduced by saving the space for each optical element.
[0139]
In addition, since three types of diffracted light, ie, 0th-order light and ± 1st-order light, can be used for two types of laser light having different wavelengths, information signals are recorded and reproduced on and from various disc-shaped recording media. Thus, the types of disk-shaped recording media that can be used are increased, and the performance of the disk drive device can be improved.
[0140]
Further, since the error signal is detected by using only the part received on one side of the sub-beam light receiving surface of the ± 1st order light, the number of areas is small, the light receiving surface is simplified, and the signal detection is simplified. be able to.
[0141]
In addition, the differential astigmatism method can be used for detecting the focusing error signal, and the accurate focusing error signal can be detected.
[0142]
According to the ninth aspect of the present invention, the first spot dividing line and the second spot dividing line for dividing the light receiving spots of the ± primary lights of the laser beams having different wavelengths on the sub beam receiving surface of the light receiving element. Since a push-pull signal can be detected for each of the laser beams having different wavelengths, a common light emitting element, diffraction element, beam splitter and light receiving element can be used for laser lights having different wavelengths. Thus, the number of parts can be reduced, and the size of the disk drive device can be reduced by saving the space for each optical element.
[0143]
In addition, since three types of diffracted light, ie, 0th-order light and ± 1st-order light, can be used for two types of laser light having different wavelengths, information signals are recorded and reproduced on and from various disc-shaped recording media. Thus, the types of disk-shaped recording media that can be used are increased, and the performance of the disk drive device can be improved.
[0144]
Further, since the error signal is detected by using only the part received on one side of the sub-beam light receiving surface of the ± 1st order light, the number of areas is small, the light receiving surface is simplified, and the signal detection is simplified. be able to.
[0145]
According to the tenth aspect of the present invention, the differential astigmatism method can be used for detecting the focusing error signal, and the accurate focusing error signal can be detected.
[Brief description of the drawings]
FIG. 1 shows an embodiment of the present invention together with FIG. 2 to FIG. 7, and FIG. 1 is a schematic perspective view of a disk drive device.
FIG. 2 is a conceptual diagram illustrating a configuration of an optical system provided in the optical pickup.
FIGS. 3A and 3B are conceptual diagrams showing the positions of spots on each light receiving surface, where FIG. 3A shows the positional relationship between the 0th order light and ± 1st order light on each light receiving surface, and FIG. 3B has a first wavelength. The position of the spot of the laser light is shown, and (c) shows the position of the spot of the laser light having the second wavelength.
FIGS. 4A and 4B are conceptual diagrams showing the positions of spots on each light receiving surface according to a first modified example, where FIG. 4A shows the positional relationship between 0th order light and ± 1st order light on each light receiving surface, and FIG. Indicates the position of the spot of the laser light having the first wavelength, and (c) indicates the position of the spot of the laser light having the second wavelength.
FIGS. 5A and 5B are conceptual diagrams showing the positions of spots on each light receiving surface according to a second modification, where FIG. 5A shows the positional relationship between the 0th order light and ± 1st order light on each light receiving surface, and FIG. Indicates the position of the spot of the laser light having the first wavelength, and (c) indicates the position of the spot of the laser light having the second wavelength.
6A and 6B are conceptual diagrams showing the positions of spots on each light receiving surface according to a third modified example, where FIG. 6A shows the positional relationship between the 0th order light and ± 1st order light on each light receiving surface, and FIG. Indicates the position of the spot of the laser light having the first wavelength, and (c) indicates the position of the spot of the laser light having the second wavelength.
FIGS. 7A and 7B are conceptual diagrams showing the positions of spots on each light receiving surface according to a fourth modification, in which FIG. 7A shows the positional relationship between 0th order light and ± 1st order light on each light receiving surface, and FIG. Indicates the position of the spot of the laser light having the first wavelength, and (c) indicates the position of the spot of the laser light having the second wavelength.
FIG. 8 is a conceptual diagram showing a conventional problem.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Disk drive device, 4 ... Disk table, 7 ... Optical pickup, 13 ... Objective lens, 14 ... Light emitting element, 15 ... Diffraction element, 16 ... Beam splitter, 19 ... Optical axis combining element, 21 ... Light receiving element, 22 ... Main beam receiving surface, 22a area dividing line, 22b area dividing line, 23 sub beam receiving surface, 23a first spot dividing line, 23b second spot dividing line, 24 sub beam receiving surface, 24a ... 1 spot dividing line, 24b: second spot dividing line, 23A: sub beam receiving surface, 23A1: first area, 23A2: second area, 23c: area dividing line, 24A: sub beam receiving surface, 24A1 ... 1 area, 24A2 ... second area, 24a ... first spot division line, 24b ... second spot division line, 24c ... area division , 23B... Sub-beam receiving surface, 23B1... First area, 23B2... Second area, 23d... Area dividing line, 23e. , 24B1 first area, 24B2 second area, 24d area division line, 24e first spot division line, 24f second spot division line, 23C sub-beam receiving surface, 23g spot division line , 24C: Sub-beam receiving surface, 24g: Spot dividing line, 23D: Sub-beam receiving surface, 23D1: First area, 23D2: Second area, 23h: Area dividing line, 24D: Sub-beam receiving surface, 24D1: First Area, 24D2: second area, 24h: area dividing line, 100: disk-shaped recording medium, 100a: CD (disk-shaped recording Body), 100b ... DVD (disc-shaped recording medium)

Claims (10)

An optical pickup that moves in a radial direction of a disk-shaped recording medium mounted on a disk table and irradiates the disk-shaped recording medium with laser light,
A light emitting element for emitting laser light having a first wavelength and a second wavelength corresponding to each of the two types of disc-shaped recording media toward two different disc-shaped recording media;
A diffractive element for diffracting a laser beam having a first wavelength and a laser beam having a second wavelength;
A beam splitter that reflects or transmits laser light having a first wavelength and laser light having a second wavelength according to the traveling direction of each laser light,
An objective lens that focuses the laser light having the first wavelength and the laser light having the second wavelength on a recording track of the disc-shaped recording medium;
An optical axis combining element that matches the optical axes of the laser light having the first wavelength and the laser light having the second wavelength reflected by each disk-shaped recording medium;
A laser beam having a first wavelength and a laser beam having a second wavelength whose optical axes are matched by the optical axis synthesizing element are incident, and the 0th-order light and ± 1st-order light of the laser light are separately received. A light receiving element having three light receiving surfaces
The three light receiving surfaces of the light receiving element are constituted by a main beam receiving surface for receiving the 0th order light and a pair of sub beam receiving surfaces which are located on opposite sides of the main beam receiving surface and receive the ± 1st order light respectively. And
The main beam receiving surface is divided into four parts by two cross-shaped area dividing lines,
A first spot dividing line for dividing each of the light receiving spots of the laser light having the first wavelength and the laser light having the second wavelength in the direction in which the three light receiving surfaces are arranged, on each of the pair of sub-beam light receiving surfaces. And a second spot dividing line. 2. The optical pickup according to claim 1, wherein each of the pair of sub-beam receiving surfaces is formed with an area dividing line that divides the sub-beam receiving surface into two in a direction orthogonal to a direction in which the three light receiving surfaces are arranged. An optical pickup that moves in a radial direction of a disk-shaped recording medium mounted on a disk table and irradiates the disk-shaped recording medium with laser light,
A light emitting element for emitting laser light having a first wavelength and a second wavelength corresponding to each of the two types of disc-shaped recording media toward two different disc-shaped recording media;
A diffractive element for diffracting a laser beam having a first wavelength and a laser beam having a second wavelength;
A beam splitter that reflects or transmits laser light having a first wavelength and laser light having a second wavelength according to the traveling direction of each laser light,
An objective lens that focuses the laser light having the first wavelength and the laser light having the second wavelength on a recording track of the disc-shaped recording medium;
An optical axis combining element that matches the optical axes of the laser light having the first wavelength and the laser light having the second wavelength reflected by each disk-shaped recording medium;
A laser beam having a first wavelength and a laser beam having a second wavelength whose optical axes are matched by the optical axis synthesizing element are incident, and the 0th-order light and ± 1st-order light of the laser light are separately received. A light receiving element having three light receiving surfaces
The three light receiving surfaces of the light receiving element are constituted by a main beam receiving surface for receiving the 0th order light and a pair of sub beam receiving surfaces which are located on opposite sides of the main beam receiving surface and receive the ± 1st order light respectively. And
The main beam receiving surface is divided into four parts by two cross-shaped area dividing lines,
An area dividing line that divides the sub-beam receiving surface into two in a direction orthogonal to the direction in which the three light-receiving surfaces are arranged, a laser beam having a first wavelength, and a laser having a second wavelength; Forming a first spot division line and a second spot division line for dividing each light receiving spot of light in the direction in which the three light receiving surfaces are arranged;
A first area and a second area are formed on the pair of sub-beam receiving surfaces by area dividing lines, respectively.
For the laser light having the first wavelength, the 0-order light received on the main beam receiving surface and the primary light received on the first area of one of the sub-beam receiving surfaces and divided by the first spot dividing line. And a push-pull signal is detected using the primary light received by the second area of the other sub-beam receiving surface and divided by the first spot dividing line,
Regarding the laser light having the second wavelength, the zero-order light received on the main beam receiving surface and the primary light received on the second area of one of the sub-beam receiving surfaces and divided by the second spot dividing line. An optical pickup characterized in that a push-pull signal is detected by using a first light beam received by a first area of the other sub-beam receiving surface and divided by a second spot dividing line. An optical pickup that moves in a radial direction of a disk-shaped recording medium mounted on a disk table and irradiates the disk-shaped recording medium with laser light,
A light emitting element for emitting laser light having a first wavelength and a second wavelength corresponding to each of the two types of disc-shaped recording media toward two different disc-shaped recording media;
A diffractive element for diffracting a laser beam having a first wavelength and a laser beam having a second wavelength;
A beam splitter that reflects or transmits laser light having a first wavelength and laser light having a second wavelength according to the traveling direction of each laser light,
An objective lens that focuses the laser light having the first wavelength and the laser light having the second wavelength on a recording track of the disc-shaped recording medium;
An optical axis combining element that matches the optical axes of the laser light having the first wavelength and the laser light having the second wavelength reflected by each disk-shaped recording medium;
A laser beam having a first wavelength and a laser beam having a second wavelength whose optical axes are matched by the optical axis synthesizing element are incident, and the 0th-order light and ± 1st-order light of the laser light are separately received. A light receiving element having three light receiving surfaces
The three light receiving surfaces of the light receiving element are constituted by a main beam receiving surface for receiving the 0th order light and a pair of sub beam receiving surfaces which are located on opposite sides of the main beam receiving surface and receive the ± 1st order light respectively. And
The main beam receiving surface is divided into four parts by two cross-shaped area dividing lines,
Forming a first spot dividing line on one of the sub-beam receiving surfaces for dividing a receiving spot of the laser beam having the first wavelength in a direction in which the three receiving surfaces are arranged;
Forming a second spot dividing line on the other sub-beam receiving surface for dividing a light receiving spot of the laser beam having the second wavelength in a direction in which the three light receiving surfaces are arranged;
The laser light having the first wavelength is pushed using the 0-order light received on the main beam receiving surface and the primary light received on one of the sub-beam receiving surfaces and divided by the first spot dividing line. Detect the pull signal,
The laser beam having the second wavelength is pushed using the 0-order light received on the main beam receiving surface and the primary light received on the other sub-beam receiving surface and divided by the second spot dividing line. An optical pickup characterized by detecting a pull signal. 5. The optical pickup according to claim 4, wherein each of the pair of sub-beam receiving surfaces is formed with an area dividing line that divides the sub-beam receiving surface into two in a direction orthogonal to a direction in which the three receiving surfaces are arranged. A disk table on which a disk-shaped recording medium is mounted and rotated, and an objective lens driving device supported on a moving base and moved in a radial direction of the disk-shaped recording medium mounted on the disk table to move the disk-shaped recording medium. A disk drive device comprising an optical pickup for irradiating a laser beam,
The optical pickup,
A light emitting element for emitting laser light having a first wavelength and a second wavelength corresponding to each of the two types of disc-shaped recording media toward two different disc-shaped recording media;
A diffractive element for diffracting a laser beam having a first wavelength and a laser beam having a second wavelength;
A beam splitter that reflects or transmits laser light having a first wavelength and laser light having a second wavelength according to the traveling direction of each laser light,
An objective lens that focuses the laser light having the first wavelength and the laser light having the second wavelength on a recording track of the disc-shaped recording medium;
An optical axis combining element that matches the optical axes of the laser light having the first wavelength and the laser light having the second wavelength reflected by each disk-shaped recording medium;
A laser beam having a first wavelength and a laser beam having a second wavelength whose optical axes are matched by the optical axis synthesizing element are incident, and the 0th-order light and ± 1st-order light of the laser light are separately received. A light receiving element having three light receiving surfaces
The three light receiving surfaces of the light receiving element are constituted by a main beam receiving surface for receiving the 0th order light and a pair of sub beam receiving surfaces which are located on opposite sides of the main beam receiving surface and receive the ± 1st order light respectively. And
The main beam receiving surface is divided into four parts by two cross-shaped area dividing lines,
A first spot dividing line for dividing each of the light receiving spots of the laser light having the first wavelength and the laser light having the second wavelength in the direction in which the three light receiving surfaces are arranged, on each of the pair of sub-beam light receiving surfaces. And a second spot dividing line. 7. The disk drive device according to claim 6, wherein each of the pair of sub-beam receiving surfaces is formed with an area dividing line that divides the sub-beam receiving surface into two in a direction orthogonal to a direction in which the three light receiving surfaces are arranged. . A disk table on which a disk-shaped recording medium is mounted and rotated, and an objective lens driving device supported on a moving base and moved in a radial direction of the disk-shaped recording medium mounted on the disk table to move the disk-shaped recording medium. A disk drive device comprising an optical pickup for irradiating a laser beam,
The optical pickup,
A light emitting element for emitting laser light having a first wavelength and a second wavelength corresponding to each of the two types of disc-shaped recording media toward two different disc-shaped recording media;
A diffractive element for diffracting a laser beam having a first wavelength and a laser beam having a second wavelength;
A beam splitter that reflects or transmits laser light having a first wavelength and laser light having a second wavelength according to the traveling direction of each laser light,
An objective lens that focuses the laser light having the first wavelength and the laser light having the second wavelength on a recording track of the disc-shaped recording medium;
An optical axis combining element that matches the optical axes of the laser light having the first wavelength and the laser light having the second wavelength reflected by each disk-shaped recording medium;
A laser beam having a first wavelength and a laser beam having a second wavelength whose optical axes are matched by the optical axis synthesizing element are incident, and the 0th-order light and ± 1st-order light of the laser light are separately received. A light receiving element having three light receiving surfaces
The three light receiving surfaces of the light receiving element are constituted by a main beam receiving surface for receiving the 0th order light and a pair of sub beam receiving surfaces which are located on opposite sides of the main beam receiving surface and receive the ± 1st order light respectively. And
The main beam receiving surface is divided into four parts by two cross-shaped area dividing lines,
An area dividing line that divides the sub-beam receiving surface into two in a direction orthogonal to the direction in which the three light-receiving surfaces are arranged, a laser beam having a first wavelength, and a laser having a second wavelength; Forming a first spot division line and a second spot division line for dividing each light receiving spot of light in the direction in which the three light receiving surfaces are arranged;
A first area and a second area are formed on the pair of sub-beam receiving surfaces by area dividing lines, respectively.
For the laser light having the first wavelength, the 0-order light received on the main beam receiving surface and the primary light received on the first area of one of the sub-beam receiving surfaces and divided by the first spot dividing line. And a push-pull signal is detected using the primary light received by the second area of the other sub-beam receiving surface and divided by the first spot dividing line,
Regarding the laser light having the second wavelength, the zero-order light received on the main beam receiving surface and the primary light received on the second area of one of the sub-beam receiving surfaces and divided by the second spot dividing line. A disk drive device wherein a push-pull signal is detected using a first light beam received by a first area of the other sub-beam receiving surface and divided by a second spot dividing line. A disk table on which a disk-shaped recording medium is mounted and rotated, and an objective lens driving device supported on a moving base and moved in a radial direction of the disk-shaped recording medium mounted on the disk table to move the disk-shaped recording medium. A disk drive device comprising an optical pickup for irradiating a laser beam,
The optical pickup,
A light emitting element for emitting laser light having a first wavelength and a second wavelength corresponding to each of the two types of disc-shaped recording media toward two different disc-shaped recording media;
A diffractive element for diffracting a laser beam having a first wavelength and a laser beam having a second wavelength;
A beam splitter that reflects or transmits laser light having a first wavelength and laser light having a second wavelength according to the traveling direction of each laser light,
An objective lens that focuses the laser light having the first wavelength and the laser light having the second wavelength on a recording track of the disc-shaped recording medium;
An optical axis combining element that matches the optical axes of the laser light having the first wavelength and the laser light having the second wavelength reflected by each disk-shaped recording medium;
A laser beam having a first wavelength and a laser beam having a second wavelength whose optical axes are matched by the optical axis synthesizing element are incident, and the 0th-order light and ± 1st-order light of the laser light are separately received. A light receiving element having three light receiving surfaces
The three light receiving surfaces of the light receiving element are constituted by a main beam receiving surface for receiving the 0th order light and a pair of sub beam receiving surfaces which are located on opposite sides of the main beam receiving surface and receive the ± 1st order light respectively. And
The main beam receiving surface is divided into four parts by two cross-shaped area dividing lines,
Forming a first spot dividing line on one of the sub-beam receiving surfaces for dividing a receiving spot of the laser beam having the first wavelength in a direction in which the three receiving surfaces are arranged;
Forming a second spot dividing line on the other sub-beam receiving surface for dividing a light receiving spot of the laser beam having the second wavelength in a direction in which the three light receiving surfaces are arranged;
The laser light having the first wavelength is pushed using the 0-order light received on the main beam receiving surface and the primary light received on one of the sub-beam receiving surfaces and divided by the first spot dividing line. Detect the pull signal,
The laser beam having the second wavelength is pushed using the 0-order light received on the main beam receiving surface and the primary light received on the other sub-beam receiving surface and divided by the second spot dividing line. A disk drive device wherein a pull signal is detected. 10. The disk drive device according to claim 9, wherein an area dividing line that divides the sub-beam receiving surface into two in a direction orthogonal to the direction in which the three light-receiving surfaces are arranged is formed on each of the pair of sub-beam receiving surfaces. .

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