WO2004068481A1

WO2004068481A1 - Optical integrated unit and optical pickup device provided with it

Info

Publication number: WO2004068481A1
Application number: PCT/JP2004/000555
Authority: WO
Inventors: Renzaburo Miki; Keiji Sakai; Tomiyuki Numata; Tetsuo Ueyama; Hiroshige Makioka; Osamu Miyazaki
Original assignee: Sharp Kabushiki Kaisha
Priority date: 2003-01-29
Filing date: 2004-01-22
Publication date: 2004-08-12
Also published as: JP2004265458A; JP4160411B2

Abstract

An optical integrated unit and an optical pickup device capable of easily preventing such troubles as erroneous detections. The light receiving surface (36) of a light receiving unit (25) is divided into one light receiving area (38a) and the other light receiving area (38b) with respect to a virtual one plane (37), and one light receiving area (38a) is subdivided into first, third and fifth light receiving area portions (41, 43, 45) and the other light receiving area (38b) into second, fourth and sixth light receiving area portions (42, 44, 46). The first to third diffraction planes (31a-31b) of a hologram (31) guide a laser beam toward first to sixth light receiving area portions (41-46) of the light receiving unit (25). An optical element (32) is provided between the light receiving unit (25) and a hologram (431) so as to transmit part (La1) of a diffraction light diffracted by the first diffraction plane (31a) of the hologram (31) and guide it to the first light receiving area portion (41) in one light receiving area (38a), and to transmit part (Lb2) of a diffraction light diffracted by the second diffraction plane (31b) and guide it to the fourth light receiving area portion (44) in the other light receiving area (38b).

Description

Specification

Optical integrated unit and optical pickup device having the same

【Technical field】

The present invention relates to an optical integrated unit for optically recording information on an information recording medium or optically reading information from the information recording medium, and an optical pickup device including the same.

[Background Art]

The first prior art optical pickup device includes a hologram for miniaturization, thinning, and high reliability. The hologram is divided into two in the radial direction of the disk, and one of the two is further divided into two in the track direction. This prior art optical pickup device detects a force error signal in half of the laser light reflected by the optical disk, a track error signal in the other half, and an information signal as a whole. In this prior art optical pickup device, there is a problem that an offset occurs due to the shift of the objective lens and the tilt of the optical disc, and the disc is determined to be a detrack even though the tracking is correct (for example, Japanese Patent Application Laid-Open No. — See Publication No. 16 1 2 82).

Techniques for solving such a problem are proposed in Japanese Patent Application No. 2002-248484. FIG. 9 is a diagram showing a schematic configuration of the optical integrated unit 1 of the second prior art. FIG. 10 is a diagram showing a positional relationship among the hologram 2, the diffraction grating 3, and the first to sixth light receiving area portions 11 to 16 in the optical integrated unit 1. As shown in FIG. The optical pickup device includes an optical integrated unit 1 and objective lens means for condensing a laser beam from the optical integrated unit 1 on an optical disk.

The optical integrated unit 1 includes a hologram 2, a diffraction grating 3, and a light receiving unit 4. The light receiving surface 5 of the light receiving portion 4 is divided into one light receiving region 7a and the other light receiving region 7b with respect to a virtual plane 6 perpendicular to the light receiving surface 5, and the one light receiving region 7a has , First, third and fifth light receiving area portions 11, 13, and 15 are provided, and the other light receiving area 7 b includes second, fourth and sixth light receiving area portions 12, 14 and 16 are provided. The hologram 2 is divided as in the first prior art described above, so that the first to It has three diffraction planes 2a to 2c. The first diffraction surface 2a guides the laser light toward the first light receiving region 11 and the second light receiving region 12 and the second diffraction surface 2b guides the laser light to the third light receiving region 13 and the fourth light receiving region. The third diffractive surface 2c guides the laser light toward the fifth light-receiving area 15 and the sixth light-receiving area 16.

A diffraction grating 3 having a different diffraction efficiency in the radial direction of the disc is interposed between the hologram 2 and the light receiving section 4. The diffraction grating 3 diffracts the laser beams L a1 and L b1 guided toward the first light receiving region portion 11 and the third light receiving region portion 13 of one light receiving region 7a. Therefore, the laser light diffracted by the diffraction grating 3 is guided to the first light receiving area portion 11 and the third light receiving area portion 13 and is canceled by the objective lens shift and the offset generated by the tilt of the optical disk. Signal is generated. As a result, offset correction of the push-pull signal can be performed, and stable tracking servo performance can be obtained.

FIG. 11 is a diagram showing transmission positions of the laser beams L a 1, L a 2, L bl, L b 2, L c 1, and L c 2 from the hologram 2 on a virtual plane including the diffraction grating 3. It is. As shown in FIG. 11, on a virtual plane including the diffraction grating 3, the laser beams guided toward the respective light receiving regions 11 to 16 are not sufficiently separated, and the third light receiving region The laser beam Lb1 guided toward the portion 13 and the laser beam Lc1 guided toward the fifth light receiving region portion 15 overlap. Therefore, in the second prior art, not only the laser beams L a 1 and L b 1 guided toward the first light receiving region portion 11 and the third light receiving region portion 13 but also the fifth light receiving region portion 15 Even the laser beam L c 1 guided toward the light is diffracted by the diffraction grating 3. That is, not only the laser light for generating the cancel signal but also the laser light for detecting the focus error signal is diffracted by the diffraction grating 3. As a result, the focus error signal is affected by the change in the transmittance due to the diffraction grating 3, and the influence appears as noise in the focus error signal. The gain cannot be increased sufficiently even if it is inserted, and the servo suppression is insufficient. Instead of the laser light L a 1, L b 1 guided toward the first light receiving area portion 11 and the third light receiving area portion 13 of one light receiving area 7 a, the second light receiving area of the other light receiving area 7 When the diffraction grating 3 is provided so as to diffract the laser beams L a 2 and L b 2 guided to the region portion 12 and the fourth light receiving region portion 14, the light is guided toward the sixth light receiving region portion 16. Even the laser beam Lc2 to be emitted is diffracted by the diffraction grating 3, so that the track error signal becomes unstable and the error rate of the information signal may be extremely deteriorated.

According to the second prior art, only the laser beams L a1 and L b1 guided toward the first light receiving region portion 11 and the third light receiving region portion 13 of one light receiving region 7a are diffracted. The diffraction grating 3 cannot be arranged to be diffracted by the grating 3. In addition, only the laser beams La2 and Lb2 guided toward the second light-receiving region portion 12 and the fourth light-receiving region portion 14 of the other light-receiving region 7b are diffracted by the diffraction grating 3. Neither can the folding grid 3 be placed. As described above, in the second prior art, there is a problem that the diffraction grating 3 cannot be arranged avoiding the optical path of the diffracted light that does not need to be diffracted by the diffraction grating 3, and erroneous detection occurs. .

DISCLOSURE OF THE INVENTION

SUMMARY OF THE INVENTION An object of the present invention is to provide an optical integrated unit and an optical pick-up device provided with the optical integrated unit, which can easily prevent the problem of erroneous detection.

The present invention has a light receiving surface perpendicular to a predetermined first axis, and divides this light receiving surface into one light receiving region and the other light receiving region with respect to a virtual plane including the predetermined first axis, A light-receiving portion provided with a plurality of light-receiving regions along a second axis at which the virtual plane intersects the light-receiving surface; and a plurality of light-receiving portions provided in the one light-receiving region. A first diffractive surface that guides the laser light toward a predetermined second light receiving area of the plurality of light receiving areas in the other light receiving area; The laser is directed toward a predetermined third light-receiving area portion of the plurality of light-receiving areas in the one light-receiving area and a predetermined fourth light-receiving area of the plurality of light-receiving areas in the other light-receiving area. Guide the light A second diffractive surface, a predetermined fifth light receiving area of the plurality of light receiving areas in the one light receiving area, and a sixth light receiving area of the plurality of light receiving areas in the other light receiving area A third diffraction surface for guiding the laser light toward the portion, a hologram provided perpendicular to the predetermined first axis and facing the light receiving surface;

A part of the diffracted light that is interposed between the light receiving unit and the hologram and diffracted by the first diffraction surface of the hologram is transmitted, guided to the first light receiving region, and by the second diffraction surface of the hologram. An optical element that transmits a part of the diffracted diffracted light and guides the diffracted light to the fourth light receiving area. According to the present invention, the light receiving surface of the light receiving section is divided into one light receiving area and the other light receiving area with respect to the virtual one plane, and one light receiving area is divided into the first, third, and fifth light receiving areas. The other light receiving area is divided into second, fourth, and sixth light receiving area portions. The hologram diffracts the guided laser beam by the first to third diffraction surfaces, and the diffracted beams are received by first to sixth light receiving regions of the light receiving unit. The optical element transmits a part of the diffracted light diffracted by the first diffraction surface of the hologram, guides the diffracted light to the first light receiving region in the one light receiving region, and diffracts the diffracted light by the second diffraction surface. Is provided between the light receiving unit and the hologram so that a part of the light is transmitted and guided to a fourth light receiving area in the other light receiving area. As described above, the position where a part of the diffracted light by the first diffraction surface toward one light receiving region of the light receiving unit and a part of the diffracted light by the second diffraction surface toward the other light receiving region of the light receiving unit are transmitted. Since the optical element is disposed, each of the diffracted lights diffracted by the first to third diffractive surfaces is converted into a diffracted light that needs to be transmitted through the optical element and a diffracted light that does not need to be transmitted through the optical element. By appropriately selecting the characteristics of the first to third diffraction surfaces of the hologram so that they can be sorted back and forth with respect to the direction along the second axis, it is not necessary to transmit the optical element. The optical element can be arranged avoiding the optical path. Therefore, it is possible to easily prevent a problem that even the diffracted light that does not need to be transmitted through the optical element is transmitted through the optical element and erroneous detection occurs.

Further, according to the present invention, the first diffractive surface is provided with + n (here, n is a positive integer greater than or equal to 1) guides the first order diffracted light, and guides the 1 n order diffracted light toward the second light receiving area,

The second diffractive surface guides + n order diffracted light toward the third light receiving region, and guides 1 n order diffracted light toward the fourth light receiving region,

The third diffractive surface guides + n-order diffracted light toward the fifth light-receiving area, and guides 1 n-order diffracted light toward the sixth light-receiving area.

According to the present invention, the first to third diffractive surfaces of the hologram guide the + nth-order diffracted light and the 1nth-order diffracted light toward predetermined light-receiving regions. The + n order and 1 n order diffracted lights from the first diffracting surface are sufficiently separated even near the hologram, and the + n order diffracted light and 1 n order diffracted light from the second diffracting surface are also well separated near the hologram. Since the + n-order diffraction light and the 1-nth-order diffraction light from the third diffraction surface are sufficiently separated even in the vicinity of the hologram, the optical element should be arranged so as to avoid the optical path of the diffracted light that does not need to pass through the optical element. Becomes easier.

Also, in the invention, it is preferable that the optical element includes a part on the optical path of a part of the diffracted light diffracted by the first diffraction surface of the hologram, and a part of the diffracted light diffracted by the second and second diffraction surfaces of the hologram. And on the optical path.

According to the present invention, on the optical path of a part of the diffracted light diffracted by the first diffraction surface of the hologram and on the optical path of a part of the diffracted light diffracted by the second diffraction surface of the hologram Since the optical elements are individually provided, unnecessary portions of the optical elements are reduced, and even the diffracted light guided to the remaining light receiving areas other than the first light receiving area and the fourth light receiving area is an optical element. It is possible to prevent the inconvenience of transmitting light as much as possible.

The present invention also provides a light emitting unit that generates laser light,

A light branching element for guiding the laser light from the light emitting section to the information recording medium and guiding the laser light reflected by the information recording medium to the hologram.

According to the invention, the light branching element guides the laser light from the light emitting section to the information recording medium, and guides the laser light reflected by the information recording medium to the hologram. hologram Guides the guided laser beam to each light receiving area of the light receiving section as described above. When such an optical integrated unit of the present invention is used in, for example, an optical pickup device, it is not necessary to separately provide a light-emitting unit and a light-receiving unit, so that adjustment of a signal detection system is not required, and assemblability is improved. Is done. Further, the optical integrated unit of the present invention including the light emitting unit and the light receiving unit can be treated as one optical component, and therefore the number of optical components is reduced.

Further, the present invention provides the optical integrated unit,

An objective lens means for converging laser light from the optical integrated unit onto an information recording medium.

According to the present invention, the objective lens means focuses the laser light from the optical integrated unit on the information recording medium, and each light receiving area of the light receiving unit of the optical integrated unit is reflected by the information recording medium. Receives laser light. Since the optical integrated unit is prevented from being erroneously detected, the information can be accurately recorded on the information recording medium or the information can be accurately read from the information recording medium.

[Brief description of the drawings]

The objects, features and advantages of the present invention will become more apparent from the following detailed description and drawings.

FIG. 1 is a diagram showing a schematic configuration of an optical integrated unit 21 according to one embodiment of the present invention.

FIG. 2 is a diagram showing a positional relationship among the hologram 31, the optical element 32, and the first to sixth light receiving area portions 41 to 46.

FIG. 3 shows the transmission positions of the diffracted light L a 1, L a 2, L bl, L b 2, L c 1, and L c 2 from the hologram 31 1 on a virtual plane including the optical element 32. FIG. FIG. 4 is a plan view schematically showing a part of the optical element 32.

FIG. 5 is a diagram showing a transmission position on the optical element 32 of the diffracted light La 1 guided toward the first light receiving area portion 41.

FIG. 6 is a diagram showing a schematic configuration of an optical integrated unit 61 according to still another embodiment of the present invention. FIG. 7 is a diagram showing a positional relationship among the hologram 31, the optical element 62, and the first to sixth light receiving area portions 41 to 46.

FIG. 8 shows the transmission positions of the diffracted lights L a 1, L a 2, L b 1, L b 2, L c 1, and L c 2 from the hologram 31 1 on a virtual plane including the optical element 62. FIG. FIG. 9 is a diagram showing a schematic configuration of the optical integrated unit 1 of the second prior art. FIG. 10 is a diagram showing the positional relationship between the hologram ² , the diffraction grating 3, and the first to sixth light receiving region portions 11 to 16 in the optical integrated unit 1. As shown in FIG.

FIG. 11 shows the transmission positions of the laser beams La1, La2, Lb1, Lb2, Lc1, and Lc2 from the hologram 2 on a virtual plane including the diffraction grating 3. FIG. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a diagram showing a schematic configuration of an optical integrated unit 21 according to one embodiment of the present invention. The optical integrated unit 21 according to the present embodiment is mounted on, for example, an optical pickup device that optically records information on an information recording medium or optically reads information from an information recording medium. The information recording medium 20 is an optical disk such as a digital versatile disk (DVD). The optical integrated unit 21 includes a light emitting section 22, a hologram element 23, a light branching element 24, and a light receiving section 25.

The light emitting section 22 is provided on the stem 26. The light emitting section 22 generates a laser beam. The light emitting section 22 is realized by, for example, a laser diode (LaD) chip. The hologram element 23 has a hologram 31 and an optical element 32. The hologram 31 is a multi-segment hologram. The optical element 32 is a diffraction grating. The light receiving section 25 is provided with first to sixth light receiving area portions 41 to 46 (see FIG. 2 to be described later), and each light receiving area portion 41 to 46 is a laser beam from the hologram element 23. The light is received.

The light splitting element 24 guides the laser light from the light emitting section 22 to the optical disk, and guides the laser light reflected by the optical disk to the hologram 31 of the hologram element 23. The optical branching element 24 has a first surface 33 and a second surface 34. The first side 3 3 The laser light from the light emitting section 22 is transmitted, and the laser light reflected by the optical disk is reflected. The second surface 34 reflects the laser light reflected by the first surface 33.

The laser light from the light emitting section 22 passes through the first surface 33 and is guided to the optical disk, and the laser light reflected by the optical disk is reflected by the first surface 33 and further by the second surface 34. The light is reflected and guided to the hologram 31 of the hologram element 23. The laser beam guided to the hologram 31 in this manner is received by the respective light receiving area portions 41 to 46 of the light receiving section 25.

When the optical integrated unit 21 according to the present embodiment is used in, for example, an optical pickup device, it is not necessary to separately provide the light emitting unit 22 and the light receiving unit 25, so that adjustment of the signal detection system is unnecessary. The assemblability is improved. Further, the optical integrated unit of the present embodiment including the light emitting section 22 and the light receiving section 25 can be handled as one optical component, and therefore the number of optical components is reduced.

FIG. 2 is a diagram showing a positional relationship among the hologram 31, the optical element 32, and the first to sixth light receiving area portions 41 to 46. The light receiving section 25 has a light receiving surface 36 perpendicular to the first axis L1 determined in advance. The light receiving surface 36 is divided into one light receiving region 38a and the other light receiving region 38b with respect to the virtual one plane 37 including the predetermined first axis L1. The hologram 31 has first to third diffraction surfaces 31a to 31c. The first to third diffraction surfaces 31a to 31c are provided perpendicular to the first axis L1 and facing the light receiving surface 36.

The hologram 31 has a circular shape, and the center of the hologram 31 is arranged on the predetermined first axis L1. A boundary 48 a between the second diffraction surface 31 b and the third diffraction surface 31 c extends from the center of the hologram 31 toward one X 1 in a first direction perpendicular to the virtual plane 37. . A boundary 48 b between the first diffraction surface 31 a and the third diffraction surface 31 c extends from the center of the hologram 31 toward the other X 2 in the first direction X. The boundary 48c between the first diffraction surface 31a and the second diffraction surface 31b is perpendicular to the predetermined first axis L1 and perpendicular to the first direction X from the center of the hologram 31. Extending in the second direction Y toward one side Y1. In one light receiving area 38a of the light receiving surface 36, along the second axis L2 where the virtual plane 37 and the light receiving surface 36 intersect, the first light receiving area portion 41, the third light receiving area An area portion 43 and a fifth light receiving area portion 45 are provided. The fifth light receiving area portion 45 is spaced apart from the hologram 31 in one direction X1 of the first direction X and is substantially the same as the hologram 31 in the direction along the second axis L2, that is, in the second direction Y. Is provided at the position. The first light receiving area portion 41 is provided at an interval in the first direction Y1 in the second direction Y more than the fifth light receiving area portion 45. The third light receiving region portion 43 is provided at a distance from the fifth light receiving region portion 45 in the second direction Y2 in the second direction Y.

In the other light receiving area 38b of the light receiving surface 36, a second light receiving area part 42, a fourth light receiving area part 44, and a sixth light receiving area part 46 are provided along the second axis L2. Can be The sixth light receiving region portion 46 is provided at an interval in the other direction X2 of the first direction X with respect to the hologram 31 and in the second direction Y at substantially the same position as the hologram 31. The second light receiving area portion 42 is provided at a distance from the other Y 2 in the second direction Y with respect to the sixth light receiving area portion 46. The fourth light receiving area portion 44 is provided at an interval in one Y1 in the second direction Y more than the sixth light receiving area portion 46.

The first light receiving area portion 41 has three portions 4 11, 4 12, and 4 13. The three portions 4 1 1, 4 1 1 2 and 4 1 3 are spaced from each other along the second axis L 2. The fourth light receiving area portion 44 has three portions 4 4 1, 4 4 2 and 4 4 3. The three parts 4 4 1, 4 4 2, 4 4 3 are spaced apart from each other along the second axis L 2. The fifth light receiving area portion 45 has two portions 451, 452. The two portions 451, 452 are provided adjacent to each other along the second axis L2.

Different diffraction gratings are formed on the first to third diffraction surfaces 31 a to 31 c of the hologram 31. The first diffraction surface 3 la includes a predetermined first light receiving region portion 41 of the plurality of light receiving region portions 41, 43, and 45 in the one light receiving region 38 a and the other light receiving region 3. The laser light is guided toward a predetermined second light receiving area portion 42 among a plurality of light receiving area portions 42, 44, and 46 in 8b. The second diffraction surface 3 lb is determined in advance among a plurality of light receiving area portions 41, 43, 45 in the one light receiving area 38a. The laser beam is guided toward a predetermined fourth light receiving region portion 44 among the plurality of light receiving region portions 42, 44, 46 in the third light receiving region portion 43 and the other light receiving region 38b. The third diffraction surface 31c is formed of a predetermined fifth light-receiving region portion 45 of the plurality of light-receiving region portions 41, 43, and 45 in the one light-receiving region 38a and the other light-receiving region 38b in the other light-receiving region 38b. The laser beam is guided toward a predetermined sixth light receiving area 46 among the plurality of light receiving areas 42, 44, 46.

In the present embodiment, the first diffraction surface 3 la guides the + 1st-order diffracted light La 1 toward the first light-receiving area portion 41, and _ 1st-order light diffraction toward the second light-receiving area portion 42 Lead La2. The second diffraction surface 31b guides the + 1st-order diffracted light Lb1 toward the third light receiving area 43, and guides the first-order diffracted light Lb2 toward the fourth light receiving area 44. The third diffraction surface 31c guides the + first-order diffracted light Lc1 toward the fifth light-receiving area portion 45, and guides the first-order diffracted light Lc2 toward the sixth light-receiving area portion. Thus, the first to third diffraction surfaces 31a to 31c of the hologram 31 are composed of the + first-order diffracted lights Lal, Lbl, Lc1 and the -first-order diffracted lights La2, Lb2, L c 2 is guided toward predetermined light receiving area portions 41 to 46. The + 1st-order diffracted light La1 and the first-order diffracted light La2 from the first diffraction surface 31a are sufficiently separated even in the vicinity of the hologram 31, and the + 1st-order diffracted light from the second diffraction surface 31b. L b 1 and the first-order diffracted light L b 2 are sufficiently separated even in the vicinity of the hologram 31, and the + first-order diffracted light L c 1 and the first-order diffracted light L c 2 from the third diffraction surface 31 c are holograms The optical element 32 should be arranged avoiding the optical path of the diffracted light La2, Lbl, Lcl, Lc2 that does not need to be transmitted through the optical element 32 because it is sufficiently separated even in the vicinity of 31. Becomes easier.

The optical element 32 is interposed between the light receiving unit 25 and the hologram 31. The optical element 32 further diffracts the + 1st-order diffracted light La1, which is a part of the diffracted light diffracted by the first diffraction surface 31a of the hologram 31, to obtain the + 1st and 0th order. The first-order diffraction light L all to L al 3 is guided to three portions 4 1 1, 4 1 2, 4 1 3 of the first light receiving area portion 41, respectively. The optical element 32 further diffracts the first-order diffracted light L b 2, which is a part of the diffracted light diffracted by the second diffraction surface 31 b of the hologram 31, so that the + 1st and 0th orders First-order diffracted light Lb2 1 to Lb23 is converted to the fourth light-receiving area. It leads to three parts 4 4 1, 4 4 2 and 4 4 3 of part 4 4 respectively.

FIG. 3 shows diffracted light L a 1, L a 2, L b l, L b 2, and L c from the hologram 31.

FIG. 3 is a diagram showing transmission positions of 1, Lc 2 on a virtual plane including an optical element 32. The optical element 32 is arranged on the optical path of the diffracted light L a 1 guided toward the first light receiving area portion 41 and the optical path of the diffracted light L b 2 guided toward the fourth light receiving area portion 44. It is placed on top.

The diffracted light Lb1 guided toward the third light receiving area portion 43 and the diffracted light Lc1 guided toward the fifth light receiving area portion 45 are partially formed on a virtual plane including the optical element 32. Are overlapping. Further, the diffracted light L a 2 guided toward the second light receiving area portion 42 and the diffracted light L c 2 guided toward the sixth light receiving area portion 46 are one on a virtual plane including the optical element 32. The parts overlap.

On the other hand, the diffracted light L a 1 guided toward the first light receiving area portion 41 on the virtual one plane including the optical element 32 includes the remaining light receiving areas excluding the first light receiving area portion 41. The diffracted lights L a2, L bl, L b2, L c 1, L c 2 guided toward the region portions 42 to 46 do not overlap and are sufficiently separated therefrom. Further, the diffracted light L b 2 guided toward the fourth light receiving area portion 4 4 on the virtual one plane including the optical element 32 includes the remaining light receiving area portions 4 1 to 4 excluding the fourth light receiving area portion 4 4. Diffracted light L a 1, L a 2, L bl, L cl, and L c 2 guided toward 43, 45, and 46 do not overlap and are sufficiently separated therefrom.

In the present embodiment, the optical element 32 transmits a part L a1 of the diffracted light diffracted by the first diffraction surface 31 a of the hologram 31 so as to allow one of the light receiving regions 38 a to pass therethrough. Of the diffracted light diffracted by the second diffractive surface 31b and transmitted through a part Lb2 of the other light-receiving area 38b. It is provided between the light receiving part 25 and the hologram 31 so as to lead to 44.

In this way, a part L a 1 of the diffracted light by the first diffraction surface 31 a toward the one light receiving area 38 a of the light receiving section 25 and the other light receiving area 38 b of the light receiving section 25 Since the optical element 32 is disposed at a position where a part of the diffracted light Lb2 by the second diffractive surface 31b that is directed therethrough is transmitted, the first to third diffractive surfaces 31a-3 Diffracted by 1 c Each diffracted light L a 1, L a 2, L bl, L b 2, L c 1, L c 2, the diffracted light L a 1, L b 2 which needs to be transmitted through the optical element 32, The hologram 31 can be distributed back and forth in the direction along the second axis L2 (second direction Y) with the diffracted lights La2, Lbl, Lcl, and Lc2 that do not need to be transmitted through the optical element 32. By selecting the characteristics of the first to third diffraction surfaces 31a to 31c, the optical paths of the diffracted lights La2, Lbl, Lcl, and Lc2 that do not need to be transmitted through the optical element 32 are selected. It is possible to dispose the optical element 32 while avoiding the problem. Therefore, up to the diffracted light L a 2, L bl, L cl, and L c 2 guided to the remaining light receiving areas 42, 43, 45, and 46 excluding the first light receiving area 41 and the fourth light receiving area 44. It is possible to easily prevent a problem that the light passes through the optical element 32 and erroneous detection occurs. FIG. 4 is a plan view schematically showing a part of the optical element 32. FIG. FIG. 5 is a diagram showing a transmission position on the optical element 32 of the diffracted light L a1 guided toward the first light receiving area portion 41. In the optical element 32, the transmittance changes in the first direction X. In the present embodiment, the optical element 32 is a diffraction grating, so that the diffraction efficiency changes in the first direction X. A plurality of grooves 51 are formed in the optical element 32 along the first direction X. The pitch P between the gratings of the optical element 32 is constant regardless of the position in the first direction X.

The duty D of the optical element 32 changes continuously in the first direction X. Assuming that the group width is WG and the land width is WL,

D = WL / (WG + WL)… expressed by (1).

The duty D of the optical element 32 gradually increases as it goes to one X1 of the first direction X. When the initial value of the duty D is set to 0.5 or more, as the duty D increases, the diffraction efficiencies of the + 1st-order and 1st-order diffracted lights diffracted by the optical element 32 decrease, and the The diffraction efficiency of the diffracted 0th-order diffracted light increases.

The duty D1 at the end of the other side X2 in the first direction X of the optical element 32 is, for example, 0.6, and the duty D2 at one end X1 of the optical element 32 in the first direction X is For example, 0.9 is selected. The data at the center between the two ends of the optical element 32 in the first direction X Utility D3 is selected to be 0.75, for example. The center between the two ends of the optical element 32 in the first direction X and the center of the hologram 31 are at the same position in the first direction X (see FIG. 3 described above).

When the transmission position of the diffracted light L a 1 guided toward the first light receiving area portion 41 on the optical element 32 moves from a predetermined position 52 to a position indicated by a virtual line 53 in FIG. That is, when the light moves to one X1 in the first direction X, the light quantity of the + 1st-order diffracted light La 11 and the 1st-order diffracted light La 13 diffracted by the optical element 32 decreases, and the 0th-order diffracted light Then the light quantity of a 1 2 increases. When the transmission position of the diffracted light L a 1 guided toward the first light receiving area portion 41 on the optical element 32 moves from a predetermined position 52 to a position indicated by a virtual line 54 in FIG. In other words, when the light moves to the other X 2 in the first direction X, the light quantity of the + 1st-order diffracted light La 11 and the 1st-order diffracted light La 13 diffracted by the optical element 32 increases, and the 0th-order diffracted light The light amount of La 12 decreases.

When the transmission position of the diffracted light L b 2 guided toward the fourth light receiving area portion 4 4 on the optical element 32 moves to one X 1 in the first direction X, the light is diffracted by the optical element 32. The light quantity of the + first-order diffracted light Lb21 and the first-order diffracted light Lb23 decreases, and the light quantity of the 0th-order diffracted light Lb22 increases. When the transmission position of the diffracted light L b 2 guided toward the fourth light receiving area portion 4 4 on the optical element 32 moves to the other X 2 in the first direction X, the light is diffracted by the optical element 32. + The light quantity of the first-order diffracted light Lb21 and the primary diffracted light Lb23 increases, and the light quantity of the zero-order diffracted light Lb22 decreases.

As shown in FIG. 1, an optical pickup unit 55 according to another embodiment of the present invention includes an optical integrated unit 21 according to the above-described embodiment and a laser beam from the optical integrated unit 21. Objective lens means including an objective lens 56 for focusing light on an optical disk. In the present embodiment, the first direction X corresponds to a predetermined radial direction of the optical disk 20, and the second direction Y corresponds to a track direction perpendicular to the radial direction of the optical disk 20. In the optical pickup device 55 of the present embodiment, based on the output signals from the respective light receiving area portions 41 to 46 of the light receiving section 25 of the optical integrated unit 21, the information signal RF and the focus error The signal FES and the track error signal TES are generated. The output signals from the three portions 41 1 to 4 13 of the first light receiving region 4 1 are S 11 to S 13, the output signal from the second light receiving region 42 is S 2, and the third light receiving The output signal from the area 43 is S 3, the output signals from the three sections 44 1 to 443 of the fourth light receiving area 44 are S 41 to S 43, and the two signals of the fifth light receiving area 45 The output signals from the parts 451 and 452 are S51 and S52, and the output signal from the sixth light receiving area 46 is S6. At this time, the information signal RF, the focus error signal FES, and the track error signal TES are expressed by the following equations (2) to (4).

RF = S 2 + S 3 + S 6… (2)

FE S = S 52-S 5 1 '(3) T E S = (S 3-S 2) — a 1 X {(S 1 2 + S 42)

— Β 1 X (S 1 1 + S 1 3 + S 41 + S 43)} ··· (4)

In Equation 4, the first term on the right-hand side is a push-pull signal (Ρ Ρ signal), and the coefficients a1 and following the second term on the right-hand side are cancel signals. The coefficient a1 is a coefficient for converting the shift amount of the objective lens 56 and the tilt amount of the optical disc 20 into an offset amount in the push-pull signal. The cancel signal is a signal for correcting an offset generated in the push-pull signal due to the shift of the objective lens 56 and the inclination of the optical disc 20 or the like.

In Equation 4, the coefficient 01 is a coefficient determined by the depth of the groove 51 of the optical element 32. The coefficient] 31 is diffracted by the optical element 32, and the + first-order diffracted lights Lall, Lb21 and the first-order diffracted lights La13, Lb23, diffracted by the optical element 32. It is a coefficient for adjusting the difference in diffraction efficiency between the 0th-order diffracted light L a12 and L b22. The coefficient 1 is obtained by diffracting the first-order diffracted light L a 1 diffracted by the first diffraction surface 31 a of the hologram 31 1 and diffracted by the second diffraction surface 31 b of the hologram 31 — the first-order diffracted light L b When 2 passes through predetermined positions on the optical element 3 2 respectively,

(S 1 2 + S 4 2)

One β 1 X (S 1 1 + S 13 + S 4 1 + S 43) = 0… (5) Is determined to satisfy. Predetermined positions on the optical element 32 are the + first-order diffracted light La1 diffracted by the first diffraction surface 31a of the hologram 31 and the one diffracted by the second diffraction surface 31b of the hologram 31. This is the transmission position of the first-order diffracted light Lb2 on the optical element 32 when there is no shift of the objective lens 56 and no tilt of the optical disc 20, that is, when there is no offset.

In the present embodiment, in the calculation after the coefficient α 1, the + first-order diffracted lights La 11 1 and Lb 21 and the first-order diffracted lights La 13 and Lb 2 diffracted by the optical element 32 are used. 3 and the 0-order diffracted light L a1 2, L b 2 2 diffracted by the optical element 32 are calculated. + 1st-order diffracted light L all, Lb 21 and 1st-order diffracted light L a1 3, Lb 23 diffracted by optical element 3 2, and 0-order diffracted light L a 1 2 diffracted by optical element 3 2 , Lb22, as described above, the direction of change in the amount of light is opposite. Therefore, the sensitivity to the shift of the objective lens 56 and the tilt of the optical disk 20 increases.

As described above, the optical pickup device 55 of the present embodiment generates the information signal RF, the focus error signal FES, and the track error signal TESS using the so-called one-beam PP method. When the one-beam PP method is used, the recording light amount can be increased and the recording speed can be increased. The optical pickup device 55 can extract only the shift of the optical axis between spots and pits on the optical disc 20, that is, the shift in the tracking direction, and correct the shift. Therefore, in the optical pickup device 55, stable tracking servo performance can be achieved regardless of the shift of the objective lens 56 and the tilt of the optical disk 20.

In the present embodiment, the objective lens means focuses the laser light from the optical integrated unit 21 on the optical disc 20, and the light receiving area of the light receiving unit 25 of the optical integrated unit 21. 41 to 46 receive the laser beam reflected by the optical disk 20. Since the optical integrated unit 21 is prevented from being erroneously detected, information can be accurately recorded on the optical disk 20 or information can be accurately read from the optical disk 20. Is improved. FIG. 6 is a diagram showing a schematic configuration of an optical integrated unit 61 according to still another embodiment of the present invention. FIG. 7 is a diagram showing a positional relationship among the hologram 31, the optical element 62, and the first to sixth light receiving area portions 41 to 46. FIG. 8 is a diagram showing transmission positions of the diffracted lights L al, La 2, L b 1, L b 2, L cl, and L c 2 from the hologram 31 1 on a virtual plane including the optical element 62. It is. Since the optical integrated unit 61 of the present embodiment is similar to the optical integrated unit 21 of the above-described embodiment, the same parts are denoted by the same reference numerals and description thereof is omitted.

In the present embodiment, the optical element 62 is provided on the optical path of the diffracted light L a 1 guided toward the first light receiving region portion 41 and the diffracted light L guided toward the fourth light receiving region portion 44. b2 on the optical path. The optical element 62 is guided toward the first light receiving region portion 44 and the first portion 62 a provided on the optical path of the diffracted light L a 1 guided toward the first light receiving region portion 41. A second portion 62b provided on the optical path of the diffracted light Lb2.

For example, the duty D 1a at the end of the other part X 2 in the first direction X of the first part 62 a is selected to be 0.6, and the duty D 2 at the end of one end X 1 of the first direction X is selected. a is chosen to be, for example, 0.9. In addition, the duty D lb of the end of the other portion X 2 in the first direction X of the second portion 6 2 b is, for example, 0.6, and the duty D 2 b of the end of one end X 1 in the first direction X is selected. Is chosen, for example, as 0.9.

In the present embodiment, on the optical path of the diffracted light L a1 guided toward the first light receiving area portion 41, and on the optical path of the diffracted light L b 2 guided toward the fourth light receiving area portion 44. In addition, since the optical elements 62 are individually provided, unnecessary portions of the optical element 62 are reduced, and the remaining light receiving areas 42, 4 3 excluding the first light receiving area 41 and the fourth light receiving area 44 are removed. , 45, and 46 can be prevented as much as possible from transmitting even the diffracted lights L a2, L bl, L cl, and L c 2 through the optical element 62. In addition, as described above, the change in the amount of light according to the transmission position on the optical element 62 of the diffracted lights La 1 and Lb 2 guided toward the first light receiving area portion 41 and the fourth light receiving area portion 44. For example, when the optical integration unit 61 of the present embodiment is used in an optical pickup device, the shift of the objective lens and the tilt of the optical disk are performed. The sensitivity of the cancel signal for correcting the offset caused by the shift can be improved.

By combining the optical integrated unit 61 of the present embodiment with objective lens means including an objective lens 66 for condensing the laser light from the optical integrated unit 61 on the optical disk 20, An optical pick-up device 65 according to still another embodiment of the present invention is realized. This optical pickup device 65 can achieve the same effect as the optical pickup device 55 of the above-described embodiment.

In the optical pickup devices 55 and 65 according to the above-described embodiments, the track error signal TES is generated based on Expression 4. However, in the optical pickup device according to still another embodiment of the present invention, The error signal TE S is given by

T E S = (S 3-S 2)-α 2 X {(S 2 + S 3)

-i3 2 X (S1 1 + S1 3 + S4 1 + S4 3)}… Generated based on (6).

In Equation 6, the first term on the right-hand side is a push-pull signal (PP signal), and the coefficients α 2 and subsequent to the second term on the right-hand side are cancel signals. The coefficient ο; 2 is a coefficient for converting the shift amount of the objective lens and the tilt amount of the optical disk into an offset amount in the push-pull signal. The coefficient / 32 is obtained by subtracting the + 1st-order diffracted light La1 diffracted by the first diffraction surface 31a of the hologram 311 and the one diffracted by the second diffraction surface 31b of the hologram 31. When the first-order diffracted light L b 2 passes through predetermined positions on the optical elements 32 and 62, respectively,

(S 2 + S 3)

— Β 2 X (S 1 1 + S 13 + S 4 1 + S 4 3) = 0… (7) is determined.

In the optical pickup device of the present embodiment that generates the track error signal TES based on Equation 6, when generating the information signal RF, the focus error signal FES, and the track error signal TES, each of the output signals S Output signals SI2 and S42 are not required among 11 to S13, S2, S3, S41 to S43, S51, S52, and S6. Therefore, the scale of the arithmetic circuit in the optical integrated unit can be reduced, In addition, the number of pins can be reduced. As a result, the optical integrated unit 21 can be further downsized, and thus the optical pickup device can be further downsized.

In the optical pickup devices 55 and 65 according to the above-described embodiments, the track error signal TES is generated based on Expression 4 or Expression 6. However, in the optical pickup devices according to still another embodiment of the present invention, , The track error signal TES is

T E S = (S 3— S 2)-α 3 X {(S 2 + S 3)

-β 3 Χ (S 1 2 + S 4 2)} ... Generated based on (8).

In Equation 8, the first term on the right-hand side is a push-pull signal (Ρ Ρ signal), and the coefficient α 3 and the subsequent terms in the second term on the right-hand side are cancel signals. The coefficient α3 is a coefficient for converting the shift amount of the objective lens and the tilt amount of the optical disc into an offset amount in the push-pull signal. The coefficient 3 is diffracted by the first diffraction surface L a 1 diffracted by the first diffraction surface 31 a of the hologram 31 1 and diffracted by the second diffraction surface 31 b of the hologram 31 1 — When the folded light L b 2 passes through predetermined positions on the optical elements 32 and 62, respectively,

(S 2 + S 3)-J 3 3 X (S 1 2 + S 4 2) = 0 It is determined so as to satisfy (9).

In the optical pickup device according to the present embodiment that generates the track error signal TES based on Equation 8, when generating the information signal RF, the focus error signal FES, and the track error signal TES, each of the output signals S 11 1 to S 13, S 2, S 3, S 41 1 to S 43, S 51, S 52, and S 6 are output signals S 11, IS, S 41, and S 43 Not required. Therefore, it is possible to reduce the scale of the operation route in the optical integrated unit 21 and to reduce the number of pins. Thereby, the optical integrated unit can be further miniaturized, and thus the optical pickup device can be further miniaturized.

The present invention may be embodied in various other forms without departing from its spirit or essential characteristics. Therefore, the above embodiments are merely illustrative in all respects. However, the scope of the present invention is defined by the appended claims, and is not limited by the specification. Further, all modifications and changes belonging to the claims are within the scope of the present invention.

[Industrial applicability]

As described above, according to the present invention, the optical element includes: a part of the diffracted light by the first diffraction surface toward one light receiving region of the light receiving unit; and a diffraction by the second diffraction surface toward the other light receiving region of the light receiving unit. It is arranged at a position where a part of light is transmitted. In the present invention in which the optical elements are arranged as described above, it is necessary to transmit each diffracted light diffracted by the first to third diffractive surfaces through the optical element and the diffracted light through the optical element. By appropriately selecting the characteristics of the first to third diffraction planes of the hologram so that they can be separated back and forth in the direction along the second axis with the unrefracted light, there is no need to transmit the optical element, for example, the third diffraction plane It is possible to dispose the optical element while avoiding the optical path of the diffracted light due to. Therefore, it is possible to easily prevent a problem that even the diffracted light that does not need to be transmitted through the optical element is transmitted through the optical element and erroneous detection occurs.

Further, according to the present invention, the first to third diffraction surfaces of the hologram guide the + nth-order diffracted light and the −nth-order diffracted light toward predetermined light receiving regions. The + n order and 1 n order diffracted lights from the first diffracting surface are sufficiently separated even near the hologram, and the + n order diffracted light and 1 n order diffracted light from the second diffracting surface are also well separated near the hologram. Since the + n-order and -n-order diffracted lights from the third diffraction surface are sufficiently separated even in the vicinity of the hologram, the optical element is avoided by avoiding the optical path of the diffracted light that does not need to pass through the optical element. It becomes easy to arrange.

Further, according to the present invention, the optical element is configured to detect a part of the diffracted light diffracted by the first diffraction surface of the hologram and a part of the diffracted light diffracted by the second diffraction surface of the hologram. Since the optical element is provided separately on the optical path, unnecessary portions of the optical element are reduced, and as a result, up to the diffracted light guided to each of the remaining light receiving regions except the first light receiving region and the fourth light receiving region. It is possible to prevent, as much as possible, a problem that the light passes through the optical element. According to the invention, the light branching element guides the laser light from the light emitting portion to the information recording medium, and the light branching element guides the laser light reflected by the information recording medium to the hologram, and the hologram guides the laser light. The emitted laser light is guided to each light receiving area of the light receiving section. When such an optical integrated unit of the present invention is used in, for example, an optical pickup device, it is not necessary to separately provide a light-emitting unit and a light-receiving unit, so that adjustment of a signal detection system is unnecessary, and assemblability is improved. Is done. Further, the optical integrated unit of the present invention including the light emitting unit and the light receiving unit can be treated as one optical component, and therefore the number of optical components is reduced.

Further, according to the present invention, the objective lens means focuses the laser beam from the optical integrated unit on the information recording medium, and each light receiving area of the light receiving unit of the optical integrated unit is reflected by the information recording medium. The received laser beam is received. Since the optical integrated unit is prevented from being erroneously detected, information can be accurately recorded on the information recording medium, or the information can be accurately read from the information recording medium, thereby improving reliability. You.

Claims

The scope of the claims

1. It has a light receiving surface perpendicular to a predetermined first axis, and divides this light receiving surface into one light receiving region and the other light receiving region with respect to a virtual plane including the predetermined first axis. A light-receiving section provided with a plurality of light-receiving areas along a second axis at which the virtual plane intersects the light-receiving surface;

The laser beam is directed toward a predetermined first light receiving region of the plurality of light receiving regions in the one light receiving region and a predetermined second light receiving region of the plurality of light receiving regions in the other light receiving region. A first diffractive surface to be guided, a third light receiving region portion among a plurality of light receiving region portions in the one light receiving region, and a fourth light receiving region among a plurality of light receiving region portions in the other light receiving region. A second diffraction surface for guiding the laser light toward the region, a predetermined fifth light receiving region among the plurality of light receiving regions in the one light receiving region, and a plurality of light receiving regions in the other light receiving region; A third diffraction surface that guides the laser beam toward a predetermined sixth light receiving area; a hologram provided perpendicularly to the predetermined first axis and facing the light receiving surface;

A part of the diffracted light that is interposed between the light receiving unit and the hologram and diffracted by the first diffraction surface of the hologram is transmitted therethrough, guided to the first light receiving region, and is converted by the second diffraction surface of the hologram. An optical element that transmits a part of the diffracted light and guides the diffracted light to the fourth light receiving area.

2. The first diffractive surface guides + n (where n is a positive integer equal to or greater than 1) order diffracted light toward the first light receiving region, and one-dimensional diffracted light toward the second light receiving region. guide the nth order diffracted light,

2. The light according to claim 1, wherein the third diffractive surface guides + n-order diffracted light toward a fifth light-receiving area, and guides 1 n-order diffracted light toward a sixth light-receiving area. 3. Integrated unit.

3. The optical element includes a part on an optical path of the diffracted light diffracted by the first diffraction surface of the hologram and a part of the diffracted light diffracted by the second diffraction surface of the hologram. 3. The optical integrated unit according to claim 1, wherein the optical integrated unit is provided separately on some optical paths.

4. A light emitting section for generating a laser beam,

4. An optical branching device for guiding a laser beam from a light emitting section to an information recording medium, and for guiding a laser beam reflected by the information recording medium to the hologram. An optical integrated unit according to one of the above.

5. The optical integrated unit according to claim 4,

An optical pickup device, comprising: an objective lens means for converging laser light from the optical integrated unit onto an information recording medium.