JP2010192008A - Optical pickup apparatus and optical disk apparatus using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical pickup apparatus which is made thin, and to provide an optical disk apparatus using the same. <P>SOLUTION: The optical pickup apparatus is constituted so that a collimator lens 5 which is freely movable in an optical direction toward the objective lens 2 from the light source 1 side, and a starting prism 7 are arranged between a light source 1 and an objective lens 2, and the starting prism 7 emits incident light in a first predetermined direction by beam shaping expansion, and a beam shaping prism 6 for emitting an incident light in a second predetermined direction orthogonal to the first predetermined direction by beam shaping expansion is arranged between the starting prism 7 and the collimator lens 5. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an optical pickup device and an optical disk device using the same.

  A conventional optical pickup device (for example, Patent Document 1 below) has the following configuration.

  In other words, a collimating lens that is movable in the optical axis direction and a rising prism are arranged between the light source and the objective lens from the light source side toward the objective lens.

In this conventional example, an attempt is made to reduce the thickness by arranging a rising prism below the objective lens. That is, as shown in FIG. 7, in the case where the rising mirror 102 is disposed below the objective lens 101, when the objective lens 101 is overlapped with the rising mirror 102 in the height direction, a part of the light beam is caused by the objective lens 101. Even if the objective lens 101 is overlapped with the rising prism in the height direction, the light beam is not blocked even if the rising prism 103 is used, so that the thickness can be reduced. .
JP 2007-213755 A

  In the above conventional example, spherical aberration correction is performed by moving the collimating lens in the optical axis direction for recording and reproduction of an optical disk used for multilayer recording. Here, the important thing is that when the collimating lens is moved in the axial direction, this rising prism has a beam shaping magnification of incident light and outgoing light so that astigmatism due to the rising prism does not occur. Is the same magnification.

  However, in order to prevent the occurrence of astigmatism in this way, when the beam shaping magnifications of the incident light and the outgoing light are made equal, in order to ensure a large optical path to the objective lens, this standing from the light source. The optical path to the raising prism must be made large, and this results in an obstacle to further thinning.

  SUMMARY OF THE INVENTION The present invention solves the above-described conventional problems, and an object thereof is to provide an optical pickup device that can be thinned and an optical disk device using the same.

  In order to achieve this object, the present invention is arranged between the light source and the objective lens, a collimating lens movable in the optical axis direction from the light source side toward the objective lens, and a rising prism, The rising prism is configured to emit incident light by expanding and shaping the incident light in a first predetermined direction, and the incident light is orthogonal to the first predetermined direction between the rising prism and the collimating lens. A beam shaping prism that emits the beam after being enlarged in the second predetermined direction is arranged, thereby achieving the intended purpose.

  As described above, according to the present invention, the collimating lens that is movable in the optical axis direction from the light source side toward the objective lens and the rising prism are arranged between the light source and the objective lens, and the rising prism is arranged. In the configuration, incident light is configured to be expanded and emitted in a first predetermined direction and a beam shaping prism is disposed between the rising prism and the collimating lens. Can do.

  That is, in the present invention, since the rising prism is configured to emit the incident light by expanding the beam shaping in the first predetermined direction, the optical path from the light source to the rising prism is made small. Thus, the thickness can be reduced.

  Further, in this way, when the rising prism is configured to emit the incident light by expanding the beam shaping in the first predetermined direction, the problem of astigmatism occurs. Between the rising prism and the collimating lens, a beam shaping prism for expanding and shaping the incident light in the second predetermined direction orthogonal to the first predetermined direction is arranged, so that the diverging light is emitted to the rising prism. Alternatively, astigmatism generated when the convergent light is incident can be canceled out by astigmatism generated by the beam shaping prism, so that the problem of astigmatism does not occur.

  An optical pickup apparatus according to an embodiment of the present invention that is used as an optical disk apparatus will be described below with reference to the accompanying drawings.

  As shown in FIG. 1, between the light source 1 for emitting blue light of 405 nm for Blu-ray Disc (hereinafter referred to as BD) and the objective lens 2, the beam splitter 3, 1 / A four-wavelength plate 4, a collimating lens 5, a beam shaping prism 6, and a rising prism 7 are arranged in this order.

  Further, as a signal detection system, a detection lens 8 and a light receiving element 9 are arranged in a direction perpendicular to the light source 1 of the beam splitter 3.

  In the above configuration, the operation will be briefly described. The 405 nm blue light emitted from the light source 1 passes through the beam splitter 3, the quarter wavelength plate 4, the collimator lens 5, the beam shaping prism 6, and the rising prism 7. Then, as shown in FIG. 2, next, the light passes through the objective lens 2 and is irradiated on one of the upper and lower recording layers 11 and 12 of the optical disk 10 such as a BD disposed above the objective lens 2. The reflected light from the recording layer 11 or 12 then passes through the objective lens 2, the rising prism 7, the beam shaping prism 6, the collimating lens 5, and the quarter wavelength plate 4. Here, the blue light emitted by the P wave from the light source 1 is changed to the S wave by passing through the quarter wavelength plate 4 twice in a reciprocating manner. A polarization separation film is formed on the beam splitter 3, and the reflected light from the recording layer 11 or 12 is reflected by the beam splitter 3 and reaches the light receiving element 9 via the detection lens 8.

  Hereinafter, feature points in the present embodiment will be described.

  The collimating lens 5 in this embodiment is a lens movable in the optical axis direction. By moving the collimating lens 5 in the optical axis direction, the divergence angle or convergence angle of the blue light incident on the objective lens 2 is changed, and the spherical aberration generated in the multilayer-recorded optical disk 10 such as BD is corrected. be able to. In the present embodiment, one collimating lens 5 is movable in the optical axis direction, but a configuration in which a plurality of lenses are combined to form a collimating lens 5 and only some of the lenses are movable in the optical axis direction. It is also good. For example, the collimating lens 5 is composed of a first lens and a second lens, the first lens is fixed, and the diverging light from the light source 1 is made to act as substantially parallel light, and the second lens is moved to the optical axis. It is configured to be movable in the direction and to change the divergence angle or the convergence angle of the light emitted from the collimating lens 5.

  In the present embodiment, the blue light direction corresponding to the X direction in the objective lens 2 shown in FIG. 1 is defined as the first predetermined direction, and the tangential direction, which is the tangential direction of the circumference of the optical disc 10. Further, the direction of blue light corresponding to the Y direction in the objective lens 2 is defined as a second predetermined direction, and the radial direction that is the radial direction of the optical disc 10 is used. The first predetermined direction and the second predetermined direction are orthogonal to each other. Further, the Z direction shown in FIG. 2 is the thickness direction of the optical pickup device.

  As is understood from FIG. 2, the rising prism 7 has a width A in the tangential direction of incident light (numerical value “9” for the sake of understanding) and a width B in the tangential direction of outgoing light (understand In order to assist, the beam is configured to be emitted by expanding the beam shaping to a numerical value “10”). In the conventional example, the rising prism 7 has an optical path from the light source 1 to the rising prism 7 in the tangential direction in order to equalize the beam shaping magnifications of the incident light and the emitted light in the tangential direction. The place where the width A had to be “10” can be reduced to “9” in the present embodiment.

  As can be understood from FIGS. 1 and 2, the rising prism 7 is substantially square when viewed from above, and is substantially triangular when viewed from the front, and the objective lens 2 faces the lower portion of the upper surface 7a. In addition, as shown in FIG. 2, the upper portion of the upper surface 7a overlaps the objective lens 2 in the height direction when viewed from the front side, so that the height direction can be reduced. I am trying. In this state, the side surface 7 b faces the emission surface 6 a of the beam shaping prism 6.

  As understood from FIG. 1, the beam shaping prism 6 is substantially triangular when viewed from above and substantially rectangular when viewed from the front, and one of the hypotenuses of the triangle in FIG. 1 faces the rising prism 7. The exit surface 6 a is the entrance surface 6 b opposite to the collimating lens 5.

  That is, the beam shaping prism 6 has an incident surface 6b and an exit surface 6a that are not parallel to each other. As can be understood from FIG. The beam shaping is also enlarged. That is, the beam shaping is expanded from the width D of incident light (numerical value “9” to aid understanding) to the width C of outgoing light (numerical value “10” to aid understanding). Both the direction of the width C of the emitted light and the direction of the width D of the incident light are radial directions that are second predetermined directions. Then, the beam shaping magnification (B / A) in the tangential direction that is the first predetermined direction of the rising prism 7 and the beam shaping magnification (C / C) in the radial direction that is the second predetermined direction of the beam shaping prism 6. / D) was set to substantially the same value.

  In the present embodiment, as described above, since the optical disk 10 is provided with the recording layers 11 and 12 above and below, when selectively recording or reproducing, the objective lens 2 opposed thereto is moved up and down. At the same time, the collimating lens 5 is moved in the optical axis direction to correct spherical aberration. At this time, since the position of the collimating lens 5 in the optical axis direction differs between when recording or reproducing on the recording layer 11 and when recording or reproducing on the recording layer 12, the light emitted from the collimating lens 5 is diverged or converged. The state is different. Astigmatism occurs when diverging light or convergent light is incident on the rising prism 7 that expands the beam shaping. Therefore, astigmatism occurs when recording or reproducing on the recording layer 11 and when recording or reproducing on the recording layer 12. Aberration will occur. In order to suppress this, in this embodiment, the beam shaping prism 6 is disposed between the collimating lens 5 and the rising prism 7. In other words, when the beam shaping prism 6 is arranged at this position, the beam shaping magnification ratio of the blue light in the tangential direction and the radial direction in the objective lens 2 becomes substantially equal, so the collimating lens 5 is moved in the optical axis direction. However, the problem of astigmatism does not occur.

  This point will be described in more detail. As described above, the rising prism 7 simultaneously expands the beam shaping in the tangential direction which is the first predetermined direction of the light passing through the objective lens 2 in FIG. A large amount of astigmatism occurs depending on the beam shaping magnification. On the other hand, the beam shaping prism 6 is intended to expand the beam shaping in the radial direction, which is the second predetermined direction passing through the objective lens 2 of FIG. A great deal of astigmatism occurs. The beam shaping magnification in the tangential direction and radial direction of light passing through the objective lens 2 is the same. In conclusion, as described above, the beam shaping magnifications in the tangential direction and the radial direction of the light passing through the objective lens 2 are substantially equal, and astigmatisms having different polarities cancel each other. Will not occur.

  In the configuration as described above, by using the rising prism 7 for expanding and shaping the beam, the height A of the optical path from the light source 1 to the rising prism 7 is reduced even if a large optical path to the objective lens is secured. Thus, the optical pickup device and the optical disk device using the same can be reduced in thickness. In addition, in such a configuration, astigmatism does not occur when the recording layers 11 and 12 of the optical disk 10 are switched.

  3 and 4 show another embodiment of the present invention, in which an optical path changing prism 13 is arranged on the incident surface 6 b side of the beam shaping prism 6. That is, as apparent from FIG. 3, the optical path changing prism 13 is substantially triangular when viewed from above, and the incident angle of the incident surface 13a is the same as that of the emitting surface 13b. The optical path is changed so that the light that has passed through the lens 5 is simply bent and supplied to the beam shaping prism 6. And by setting it as such a structure, as shown in FIG. 3, the emitted light from the light source 1 and the emitted light from the output surface 6a of the beam shaping prism 6 to the standing prism 7 are made into a parallel state. As a result, each component shown in FIG. 3 can be designed and assembled very easily.

  5 and 6 show still another embodiment of the present invention, in which an optical path changing prism 14 is disposed on the exit surface 6 a side of the beam shaping prism 6. That is, since the incident angle of the incident surface 14a and the exit angle of the exit surface 14b of the optical path changing prism 14 are the same, the optical path is changed so that the light passing through the beam shaping prism 6 is simply bent. This is supplied to the rising prism 7. And by setting it as such a structure, as shown in FIG. 5, the emitted light from the light source 1 and the emitted light from the output surface 14b of the optical path change prism 14 to the standing prism 7 are made into a parallel state. As a result, each component shown in FIG. 5 can be designed and assembled very easily.

  3 to 6, the optical path changing prisms 13 and 14 simply change the optical path. However, these optical path changing prisms 13 and 14 have a beam shaping function. It may be given. When the beam shaping function is added to the optical path changing prisms 13 and 14 as described above, the total second beam shaping magnification ratio (C ( The numerical value “10” for assisting understanding) / D (the numerical value “9” for assisting understanding)) and the beam shaping magnification (B (for assisting understanding) in the first predetermined direction of the rising prism 7). It is important that the value is substantially the same as “10”) / A (“9” in order to help understanding)).

  In the present embodiment, the light source 1 emits 405 nm blue light for BD, but may emit 650 nm red light for DVD. That is, the light source 1 is used for recording / reproduction in multi-layer recording and does not ask the wavelength.

  As described above, according to the present invention, the collimating lens that is movable in the optical axis direction from the light source side toward the objective lens and the rising prism are arranged between the light source and the objective lens, and the rising prism is arranged. Has a configuration in which incident light is beam-shaped and enlarged in a first predetermined direction and is emitted, and a second light orthogonal to the first predetermined direction is incident between the rising prism and the collimating lens. Since a beam shaping prism for expanding and shaping the beam in a predetermined direction is arranged, the thickness can be reduced.

  That is, in the present invention, since the rising prism is configured to emit the incident light by expanding the beam shaping in the first predetermined direction, the optical path from the light source to the rising prism is made small. Thus, the thickness can be reduced.

  Further, in this way, when the rising prism is configured to emit the incident light by expanding the beam shaping in the first predetermined direction, the problem of astigmatism occurs. Between the rising prism and the collimating lens, a beam shaping prism for expanding and shaping the incident light in the second predetermined direction orthogonal to the first predetermined direction is arranged, so that the diverging light is emitted to the rising prism. Alternatively, the astigmatism generated when the convergent light is incident can be canceled out by the astigmatism generated by the beam shaping prism, so that the problem of astigmatism does not occur.

  Therefore, it is expected to be utilized for a recording / reproducing apparatus such as a personal computer, a BD, or a DVD.

Top view of one embodiment of the present invention Front view Top view of another embodiment of the present invention Front view Top view of yet another embodiment of the invention Front view Front view of rising prism and objective lens, and rising mirror and objective lens

DESCRIPTION OF SYMBOLS 1 Light source 2 Objective lens 3 Beam splitter 4 1/4 wavelength plate 5 Collimating lens 6 Beam shaping prism 6a Output surface 6b Incident surface 7 Rising prism 7a Upper surface 7b Side surface 8 Detection lens 9 Light receiving element 10 Optical disk 11, 12 Recording layer 13, 14 Optical path changing prism 13a, 14a Incident surface 13b, 14b Output surface

Claims (8)

Between the light source and the objective lens, a collimating lens that is movable in the optical axis direction from the light source side toward the objective lens and a rising prism are arranged, and the rising prism transmits the incident light to the first lens. The beam shaping is expanded and emitted in a predetermined direction, and the incident light is beam shaped and expanded in a second predetermined direction perpendicular to the first predetermined direction between the rising prism and the collimating lens. An optical pickup device in which an outgoing beam shaping prism is arranged. The optical pickup device according to claim 1, wherein the beam shaping prism has an entrance surface and an exit surface that are not parallel. The optical pickup device according to claim 1, wherein the beam shaping prism has an incident angle of an incident surface larger than an exit angle of an output surface. 4. The beam shaping magnification ratio of the rising prism in the first predetermined direction and the beam shaping magnification ratio of the beam shaping prism in the second predetermined direction are set to substantially the same value. 5. An optical pickup device according to any one of the above. 5. The optical pickup device according to claim 1, wherein an optical path changing prism is disposed on an incident surface side or an output surface side of the beam shaping prism. The optical pickup device according to claim 5, wherein the optical path changing prism has a beam shaping function. The total beam shaping magnification ratio of the beam shaping prism and the optical path changing prism in the second predetermined direction orthogonal to the first predetermined direction is set to the beam shaping prism in the first predetermined direction. The optical pickup device according to claim 6, wherein the optical pickup device has substantially the same value as the magnification. An optical disk device using the optical pickup device according to claim 1.

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