JP2004247032A - Optical head, optical information recording/reproducing device, computer, video recording/reproducing device, video reproducing device, server, and car navigation system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical head capable of dealing with high multiple-fold speed recording, a dual layer disk or the like by improving light using efficiency. <P>SOLUTION: In a beam shaping lens for shaping an elliptical beam emitted from a light source into a roughly circular beam, a pair of cylindrical surfaces bent in the same direction are provided, the cylindrical surface near the light source is aspherical, and the cylindrical surface far from the light source is spherical. Thus, the optical head in which abberation is reduced even when a beam shaping magnification is about twice is obtained. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

  The present invention relates to an optical head, an optical information recording / reproducing apparatus for recording or reproducing information by irradiating an optical disk with light from the optical head, and a computer, a video recording / reproducing apparatus, a video reproducing apparatus, a server, and a car navigation using the same. It is about the system.

  As a high-density, large-capacity optical information recording medium, an optical disk called a DVD (Digital Versatile Disk) is commercially available. Such an optical disk has been rapidly spreading recently as a recording medium for recording images, music, and computer data. In recent years, research on next-generation optical discs with further increased recording density has been promoted in various places. The next-generation optical disk is expected as a recording medium that replaces a video tape of a mainstream VTR (Video Tape Recorder), and is being developed at a rapid pace.

  An optical head that records or reproduces information on an optical disk includes a light source, an objective lens that focuses a beam emitted from the light source on the optical disk, and a detector that detects a beam reflected from the optical disk. Since a semiconductor laser as a light source emits a beam from an end face of a thin active layer, the beam has an elliptical shape, and the ratio of the short axis to the long axis is approximately 1: 3. When information is recorded on an optical disk, it is desired to shape an elliptical beam into a circle from the viewpoint of improving light use efficiency.

  Next, first to fourth conventional examples for shaping a beam will be described.

  FIG. 16 shows a first conventional example in which a beam is shaped into a circle by a lens (see, for example, Japanese Utility Model Laid-Open No. 63-118714 (FIGS. 1 and 4) (Patent Document 1)). FIG. 3 shows a schematic diagram of an optical head 309 using a beam shaping lens 302. The elliptical divergent beam emitted from the light source 301 becomes a circular divergent beam by a beam shaping lens 302 described later, passes through a branching prism 303, becomes a parallel beam by a collimating lens 304, is reflected by a mirror 305, and is reflected by an objective lens 306. The light is condensed and irradiated on the optical disk 310. The beam reflected by the optical disk 310 follows the reverse path, is reflected by the branch prism 303, and is detected by the detector 308.

  The beam shaping lens 302 has cylindrical surfaces on both sides. The beam is refracted and expanded by the cylindrical surface along the minor axis direction of the beam, and is transmitted along the major axis direction without changing the spread angle. The elliptical beam is shaped into a circular beam.

  FIG. 17 shows a second conventional example using a cylindrical lens 302a and a cylindrical lens 302b provided spatially separated (for example, Japanese Utility Model Laid-Open No. 63-118714 (FIGS. 1 and 4)). ) (See Patent Document 1)). Even in such a configuration, an elliptical beam can be shaped into a circular beam as in the first conventional example.

  FIG. 18 shows a third conventional example in which a beam is shaped into a circle by a lens (for example, see JP-A-2002-208159 (FIG. 1) (Patent Document 2)). The beam shaping lens 402 has a first surface 402i and a second surface 402o which are cylindrical surfaces. The beam is refracted and expanded by the cylindrical surface along the minor axis direction of the beam, and the divergence angle along the major axis direction is increased. The beam is shaped by transmitting the beam unchanged. Since the first surface 402i is an aplanatic surface, no aberration occurs. Since the distance on the optical axis from the light emitting point of the light source 401 to the first surface 402i is the same as the thickness on the optical axis of the beam shaping lens 402, the beam in the short axis direction is perpendicularly incident on the second surface 402o, No aberration occurs. The second surface 402o has a non-circular cross section in a plane perpendicular to the central axis of the cylindrical surface (a surface parallel to the plane of FIG. 18) (hereinafter, such a cylindrical surface is referred to as an aspheric cylindrical surface). Call). The second surface 402o is formed as an aspheric cylindrical surface, and generates the same degree of aberration in the short axis direction as in the long axis direction, thereby providing spherical rotationally symmetric spherical aberration. The spherical aberration generated by the beam shaping lens 402 is removed by the collimator lens 404.

FIG. 19 is a fourth conventional example in which the shape of a beam is shaped into a circle by a prism, and shows a schematic diagram of an optical head 509 using a beam shaping prism 502. The divergent beam emitted from the light source 501 becomes a parallel beam by the collimating lens 504, and the beam is refracted by the beam shaping prism 502 along the short axis direction of the beam, whereby the elliptical beam is shaped into a circular beam. The circular beam passes through the splitting prism 503, is reflected by the mirror 505, is collected by the objective lens 506, and is irradiated on the optical disc 510. The beam reflected by the optical disk 510 follows the reverse path, is reflected by the splitting prism 503, passes through the detection lens 507, and is detected by the detector 508.
JP-A-63-118714 (FIGS. 1 and 4) JP-A-2002-208159 (FIG. 1)

  However, the beam shaping magnification of the beam shaping lens 302 of the first conventional example shown in FIG. 16 is limited to about 1.2 times. The cylindrical surface of the beam shaping lens 302 has a simple substantially arc-shaped cross section on a plane perpendicular to the center axis of the cylindrical surface (a surface parallel to the paper surface of FIG. 16) (hereinafter, such a cylindrical surface is referred to as a spherical surface). Called the cylindrical surface). If the shaping magnification of the beam is set to 2 or more to obtain a substantially circular beam, high order aberrations of 0.06λ (λ is the wavelength of the beam) or more occur due to the spherical cylindrical surface, which is not practical. Was.

  Also, in the case where the cylindrical lens 302a and the cylindrical lens 302b of the second conventional example shown in FIG. 17 are used, high-order aberrations are similarly generated when the beam shaping magnification is set to 2 times or more. In addition, since the cylindrical lens 302a and the cylindrical lens 302b are spatially separated, there has been a problem that the interval thereof fluctuates due to a temperature change, thereby changing a beam shaping magnification or deteriorating aberration.

  The optical head of the present invention includes a light source, a beam shaping lens that shapes an elliptical divergent beam emitted from the light source into a substantially circular divergent beam, and a collimating lens that converts the substantially circular divergent beam into a substantially parallel beam. Wherein the beam shaping lens is curved in the same direction in an optical head comprising an objective lens for condensing the substantially parallel beam on an optical information recording medium and a detector for detecting a beam reflected on the optical information recording medium. A pair of cylindrical surfaces, one of the cylindrical surfaces being an aspherical surface, and the other being a spherical surface. With such a configuration, high-order aberrations can be suppressed and good recording and reproduction can be performed.

  In the beam shaping lens, it is preferable that a cylindrical surface close to the light source is an aspheric surface, and a cylindrical surface far from the light source is a spherical surface. With such a configuration, high-order aberrations can be suppressed to a lower level and good recording and reproduction can be performed.

  Preferably, the beam shaping lens has a square cross section perpendicular to the optical axis. With such a configuration, the beam shaping direction can be easily determined.

  Further, the material of the beam shaping lens is preferably glass. With such a configuration, variation in aberration due to temperature change can be suppressed to a small value.

  In addition, it is preferable that a fixed position between the base on which the beam shaping lens is mounted and the beam shaping lens is closer to the light source than the center of the beam shaping lens. With such a configuration, variation in aberration due to temperature change can be suppressed to a small value.

  Preferably, the base on which the beam shaping lens is mounted and the beam shaping lens are fixed on a plane perpendicular to a central axis of a cylindrical surface of the beam shaping lens. With such a configuration, variation in aberration due to temperature change can be suppressed to a small value.

  Further, it is preferable that the base on which the beam shaping lens is mounted and the beam shaping lens are press-bonded by a spring that presses along a central axis direction of a cylindrical surface of the beam shaping lens. With such a configuration, variation in aberration due to temperature change can be suppressed to a small value.

  Further, it is preferable that the beam shaping lens includes two cylindrical lenses, and the two cylindrical lenses are joined. With such a configuration, a beam shaping lens can be easily manufactured.

  Further, it is preferable that the surface where the two cylindrical lenses are joined is a flat surface. With such a configuration, position adjustment and rotation adjustment of the two cylindrical lenses are facilitated.

  Further, it is preferable that the two cylindrical lenses have different cross-sectional sizes perpendicular to the optical axis. With such a configuration, the beam shaping lens can be easily mounted on the base.

  Further, it is preferable that the two cylindrical lenses have a cross section perpendicular to the optical axis, and the size of the cylindrical lens close to the light source is larger. With such a configuration, the light source side of the beam shaping lens can be fixed to the base. That is, variation in aberration due to temperature change is suppressed to a small value.

  Further, it is preferable that the two cylindrical lenses have different thicknesses along the optical axis. With such a configuration, the position of the beam shaping lens can be stably adjusted.

  Further, it is preferable that the thickness of the two cylindrical lenses along the optical axis is larger for the cylindrical lens closer to the light source. With such a configuration, the light source side of the beam shaping lens can be fixed to the base.

  Preferably, the light source and the beam shaping lens are fixed to the same holder. With such a configuration, variation in aberration due to temperature change can be suppressed to a small value.

  Further, it is preferable that the holder has a tilt adjustment mechanism for correcting an optical axis tilt of the light source. With such a configuration, it is possible to correct the optical axis tilt of the light source while suppressing the variation in aberration due to the temperature change.

  Preferably, the holder has a position adjusting mechanism for correcting a position error of a light emitting point of the light source. With such a configuration, it is possible to correct the position of the light emitting point while suppressing aberration fluctuation due to temperature change.

  Preferably, the holder is press-fitted into the optical table of the optical head by a press. With such a configuration, variation in aberration due to temperature change can be suppressed to a small value.

  Further, it is preferable that the holder is fixed by caulking to the optical table of the optical head. With such a configuration, variation in aberration due to temperature change can be suppressed to a small value.

  Preferably, the holder is welded to an optical table of the optical head. With such a configuration, variation in aberration due to temperature change can be suppressed to a small value.

  Further, it is preferable that the collimating lens is movable in an optical axis direction. With such a configuration, it is possible to correct spherical aberration while suppressing costs.

  An optical head according to the present invention includes a light source, a beam shaping lens that shapes an elliptical divergent beam emitted from the light source into a substantially circular divergent beam, and a collimating lens that converts the substantially circular divergent beam into a substantially parallel beam. An optical head comprising: an objective lens for condensing the substantially parallel beam on an optical information recording medium; and a detector for detecting a beam reflected on the optical information recording medium, a base on which the beam shaping lens is mounted. The fixed position of the beam shaping lens and the beam shaping lens is closer to the light source than the center of the beam shaping lens.

  Preferably, the apparatus further includes an adhesive applied only to a side of the beam shaping lens close to the light source to bond the beam shaping lens and the base.

  It is preferable that an elastic body that presses the beam shaping lens be provided on a side of the beam shaping lens closer to the light source.

  It is preferable that the base has a convex shape with respect to the beam shaping lens on a side close to the light source.

  It is preferable that the base has a concave shape with respect to the beam shaping lens between a side near and far from the light source.

  An optical information recording / reproducing apparatus according to the present invention includes an optical head according to the present invention, a rotation system or a transport system for relatively moving the optical head and the optical information recording medium, and the optical head based on a signal obtained from the optical head. It has a control circuit for controlling the head, the rotation system and the transfer system. With such a configuration, information can be recorded or reproduced on the optical information recording medium.

  A computer according to the present invention includes the optical information recording / reproducing device according to the present invention as an external storage device. With such a configuration, information can be recorded or reproduced on the optical information recording medium.

  A video recording / reproducing apparatus according to the present invention includes the optical information recording / reproducing apparatus according to the present invention, and records and reproduces a video on an optical information recording medium. With such a configuration, information can be recorded or reproduced on the optical information recording medium.

  A video reproducing apparatus according to the present invention includes the optical information recording / reproducing apparatus according to the present invention, and reproduces a video from an optical information recording medium. With such a configuration, information can be reproduced from the optical information recording medium.

  The server according to the present invention is provided with an optical information recording / reproducing device as an external storage device. With such a configuration, information can be recorded or reproduced on the optical information recording medium.

  A car navigation system according to the present invention includes the optical information recording / reproducing device according to the present invention as an external storage device. With such a configuration, information can be recorded or reproduced on the optical information recording medium.

  ADVANTAGE OF THE INVENTION According to this invention, the advantageous effect that the utilization efficiency of light improves and it can respond to high-speed recording, a double layer disc, etc. is acquired.

  Hereinafter, an embodiment of the present invention will be described with reference to FIGS. 1 to 15. The same reference numerals in the following drawings represent those having the same effect.

(Embodiment 1)
1A and 1B show an optical head 9 according to Embodiment 1 of the present invention. FIG. 1A is a top view of the optical head 9, and FIG. 1B is a side view. Since the beam emitted from the light source 1 is emitted from the end face of the thin active layer, the shape is elliptical, and the ratio of the short axis to the long axis is approximately 1: 3. The elliptical divergent beam emitted from the light source 1 is converted into a substantially circular divergent beam by a beam shaping lens 2 described later, transmitted through the splitting prism 3, converted into a substantially parallel beam by the collimating lens 4, reflected by the mirror 5, and reflected by the objective lens. The light is condensed by 6 and irradiated on the optical disk 10. The beam reflected by the optical disk 10 follows the reverse path, is reflected by the branching prism 3, passes through the detection lens 7, and is detected by the detector 8. The objective lens 6 is driven in a focus direction or a tracking direction by an objective lens actuator 61 based on a detection signal obtained by the detector 8.

  Further, in the present embodiment, the light source 1, the beam shaping lens 2, the branch prism 3, the collimating lens 4, the mirror 5, the detection lens 7, the detector 8, and the objective lens actuator 61 are fixed to a base 16 described later.

  FIG. 2 shows a perspective view of the beam shaping lens 2 according to the first embodiment of the present invention. The beam shaping lens 2 has a pair of cylindrical surfaces curved in the same direction. When a direction along the optical axis A3 is represented by z, a central axis direction of the cylindrical surface is represented by y, and a direction perpendicular to the z direction and the y direction is represented by x, the cylindrical surface of the first surface 2i closer to the light source 1 is xz The cross section of the plane is a non-circular arc (hereinafter, such a cylindrical surface is referred to as an aspherical cylindrical surface). The cylindrical surface of the second surface 2o farther from the light source 1 has a simple substantially arcuate cross section in the xz plane (hereinafter, such a cylindrical surface is referred to as a spherical cylindrical surface). Due to the beam shaping lens 2, the elliptical beam is refracted along the major axis direction and contracts as shown in FIG. 1A, while it spreads along the minor axis direction as shown in FIG. 1B. By transmitting the light without changing the angle, the elliptical beam is shaped into a substantially circular beam, and the ratio of the short axis to the long axis is from 1: 3 of the elliptical beam to 1: 1 to 1: 2 of the approximately circular beam. About. As described above, by shaping the beam into a substantially circular shape, the light use efficiency is improved, the light power of the spot focused on the optical disk 10 is increased, and it is possible to cope with high-speed recording, a double-layer disk, and the like. Become.

  The difference from the first conventional example described above with reference to FIG. 16 is that the first surface 2i is an aspheric cylindrical surface. In the first conventional example, since no aspheric cylindrical surface is used, higher-order aberrations are generated at 0.06λ (λ is the wavelength of the beam) or more. However, according to the first embodiment, the aspheric cylindrical surface is used. By using a surface, not only on-axis but also off-axis aberrations can be minimized, and high-order aberrations can be suppressed to 0.005λ or less. As a result, good recording and reproduction can be performed.

  In manufacturing a lens, the spherical cylindrical surface can easily polish the lens surface because the lens surface can be polished while rotating a round bar. On the other hand, since an aspherical cylindrical surface cannot be formed, it is difficult to accurately process the lens surface. For these reasons, aspherical cylindrical surfaces tend to have cutting marks and undulations, and the aberrations tend to be worse.

  As described above, in order to satisfy the aberration performance, an aspherical cylindrical surface is required in lens design, while a spherical cylindrical surface is preferable in lens production. Embodiment 1 of the present invention is that one surface is an aspherical cylindrical surface and the other surface is a spherical cylindrical surface. Thus, since the design and fabrication of the lens are considered at the same time, a beam shaping lens having good aberration performance can be realized.

  By the way, since the beam emitted from the light source 1 is divergent, the effective diameter of the beam differs between the first surface 2i and the second surface 2o. If the first surface 2i having a small effective diameter of the beam is an aspherical cylindrical surface and the second surface 2o having a large effective diameter of the beam is a spherical cylindrical surface, the effect of the processing error of the lens can be minimized. There is an effect that good aberration characteristics can be obtained.

  In the third conventional example described above with reference to FIG. 18, the first surface 402i is an aplanatic surface, the second surface 402o is an aspherical cylindrical surface, and the distance from the light emitting point of the light source 401 to the first surface 402i. And the beam shaping lens 402 have the same thickness, but Embodiment 1 is completely different. The third conventional example has a design in which no aberration occurs on each of the first surface 402i and the second surface 402o. However, in the first embodiment of the present invention, aberration occurs on the total of the first surface 2i and the second surface 2o. They differ in that they do not design.

  The beam shaping in which the first surface 2i is a convex surface and the second surface 2o is a concave surface to reduce the major axis direction of the beam can increase the focal length of the collimating lens 4, and thus the light emitting point due to the temperature change of the light source 1 There is an advantage that tolerance for movement is increased. On the other hand, in the case of beam shaping that enlarges the minor axis direction of the beam, the first surface 2i may be a concave surface and the second surface 2o may be a convex surface. In this case, since the focal length of the collimating lens 4 can be shortened, there is an advantage that the optical head 9 is reduced in size.

  2, the cross-sectional shape of the beam shaping lens 2 on the xy plane (plane perpendicular to the optical axis A3) is a quadrangle. By making the shape of a square, the bottom surface 2c of the beam shaping lens 2 is flatly rubbed against the base 16 on which the beam shaping lens 2 is mounted, so that the beam shaping lens 2 can be stably placed. That is, since the rotation θ of the beam shaping lens 2 around the z-axis can be restricted, the beam shaping direction can be easily determined. The beam shaping lens 2 needs to be positioned in the z direction and the x direction with respect to the light source 1 in order to obtain aberration performance. Since the bottom surface 2c of the beam shaping lens 2 can be brought into a plane-to-plane state with respect to the base 16, there is an advantage that the position can be stably adjusted.

  The beam shaping lens 2 can be formed in a circular shape in cross section, and a flat portion (bottom portion 2c) can be formed by cutting.

  If an ultraviolet-curing adhesive 14 is applied between the bottom surface 2c and the base 16, the beam shaping lens 2 can be easily fixed by irradiating ultraviolet rays after adjusting the position of the beam shaping lens 2. Generally, an adhesive expands or contracts due to a change in temperature. As shown in FIG. 2, the adhesive 14 applied on the xz plane (the plane perpendicular to the central axes A1 and A2 of the cylindrical surface) expands and contracts uniformly in the x and z directions due to a temperature change. Does not move in the x and z directions. However, the adhesive 14 expands and contracts in the y direction due to a temperature change, and moves the beam shaping lens 2 in the y direction. However, since the first surface 2i and the second surface 2o merely move in the y direction, no change occurs in the optical characteristics. As described above, the first embodiment of the present invention has an advantageous advantage that the optical characteristics are not deteriorated by an environmental change such as a temperature change.

  Further, since the optical bench on which the optical components are mounted is made of metal or resin, expansion or contraction occurs due to a temperature change. Accordingly, the distance between the light source 1 and the beam shaping lens 2 fluctuates, and astigmatism occurs. In the first embodiment of the present invention, the fixing position of the beam shaping lens 2 by the adhesive 14 is set closer to the light source 1 than the center (closer to the first surface 2i). Accordingly, the distance between the light source 1 and the fixed position of the beam shaping lens 2 is shortened, so that the expansion and contraction of the base 16 with respect to a temperature change can be reduced. As a result, the fixed position of the light source 1 and the beam shaping lens 2 can be reduced. Is smaller than the case where the fixed position is closer to the second surface 2o from the center, so that the effect of reducing the fluctuation of astigmatism is obtained.

  When the light source 1 emits a blue laser, the beam shaping lens 2 is made of glass, and the base 16 is made of a metal such as aluminum and zinc, the light source 1 emits light between the light emitting point and the first surface 2i. Is preferably 1 mm or more and 2 mm or less.

  As shown in FIG. 3A, the beam shaping lens 2 may be pressed and fixed in the y direction (the central axis direction of the cylindrical surface) by the spring 15. By pressing only along the y direction, the beam shaping lens 2 does not move in the x direction and z direction even if the base 16 expands and contracts due to a temperature change, and the beam shaping lens 2 moves in the y direction. Also, since the first surface 2i and the second surface 2o only move in the y direction, there is an advantageous effect that no change occurs in the optical characteristics. Also in this case, if the position where the spring 15 presses the beam shaping lens 2 is closer to the light source 1 than the center, the effect of reducing the fluctuation of astigmatism is obtained.

  Next, a preferred embodiment in which the fixed position of the beam shaping lens 2 is arranged so that the increase in astigmatism with respect to a temperature change is reduced will be described with reference to FIGS. 3B to 3D.

  FIG. 3B is an explanatory diagram of another spring retainer of the beam shaping lens according to the first embodiment. By applying an adhesive 14 for adhering the base 16 and the beam shaping lens 2 only to the side of the beam shaping lens 2 close to the light source 1, a fixed position is arranged on the side of the beam shaping lens 2 close to the light source 1. As a result, the effect that the fluctuation of astigmatism can be reduced can be obtained. Furthermore, when the side of the beam shaping lens 2 close to the light source 1 is pressed by the spring 15, the increase of astigmatism can be suppressed more stably and without variation.

  FIG. 3C is an explanatory diagram of another base 16A on which the beam shaping lens according to the first embodiment is mounted. The base 16A has a convex shape with respect to the beam shaping lens 2 on the side close to the light source as shown in FIG. 3C. An adhesive 14 for adhering the base 16A and the beam shaping lens 2 is applied to the convex portion. When the base 16A has a convex shape with respect to the beam shaping lens 2 as described above, it is possible to more stably suppress the increase of astigmatism without variation.

  FIG. 3D is an explanatory diagram of still another base on which the beam shaping lens according to the first embodiment is mounted. As shown in FIG. 3D, the base 16B has a concave shape, for example, a groove with respect to the beam shaping lens 2, between a side closer to and farther from the light source 1 of the base 16B. When the base 16B is configured in this manner, the fixed angle of the beam shaping lens 2 around the x-axis shown in FIG. 3D can be stabilized, and the increase in astigmatism can be suppressed without variation. When fixing the base 16A and the beam shaping lens 2 with an adhesive, the adhesive 14 may be applied to the side of the base 16B close to the light source 1.

  3C and 3D, when the side of the beam shaping lens 2 close to the light source 1 is pressed by the spring 15, as described above with reference to FIG. Increase can be suppressed.

  In Embodiment 1 of the present invention, the beam shaping lens 2 is made of glass. The beam shaping lens 2 itself expands and contracts due to a change in temperature, and astigmatism occurs. Since glass has a smaller coefficient of thermal expansion than resin, there is an advantage that aberration fluctuation due to temperature change can be suppressed to a small value.

(Embodiment 2)
FIG. 4A and FIG. 4B show an optical head 29 according to the second embodiment of the present invention. The difference from the first embodiment is that the beam shaping lens 22 is composed of a cylindrical lens 22a and a cylindrical lens 22b. FIG. 5 shows a perspective view of the beam shaping lens 22.

  Conventionally, axial rotation symmetry has been dealt with in the production of lenses, so that it is not necessary to adjust the rotation of the front and rear surfaces of the lens. However, in a lens that is not axially symmetric such as the beam shaping lens 2 of the first embodiment, it is necessary to pay attention to a rotation error between two surfaces. When the beam shaping magnification is about twice, a large aberration occurs due to a rotation error. For this reason, the rotation tolerance is strict at 0.05 degrees or less. In the second embodiment, since the beam shaping lens 22 has a configuration in which the cylindrical lens 22a and the cylindrical lens 22b are divided into two, the lens can be easily manufactured as in the case of the ordinary cylindrical lens.

  The difference from the second conventional example described above with reference to FIG. 17 is that the cylindrical lens 22a and the cylindrical lens 22b are joined. In the second conventional example, since the two cylindrical lenses 302a and 302b are spatially separated from each other, there has been a problem that the interval thereof fluctuates due to a temperature change, and the beam shaping magnification and aberration change.

  According to the second embodiment, since the cylindrical lens 22a and the cylindrical lens 22b are joined by the adhesive, the thickness variation due to the temperature change of the thin film adhesive can be ignored, and the beam shaping magnification and the aberration change. Absent. That is, a beam shaping lens 22 that is stable against environmental changes can be obtained.

  Since the beam shaping lens 22 is divided into two, the center axes A1 and A2 of the cylindrical surfaces of the first surface 22i and the second surface 22o are parallel and intersect with the optical axis A3. , The position adjustment of the cylindrical lens 22a and the cylindrical lens 22b along the x direction and the rotation adjustment along the θ direction are required. By making the joining surface flat, position adjustment and rotation adjustment become easy. Also, as shown in FIG. 5, when the sizes of the cylindrical lens 22a and the cylindrical lens 22b are made different from each other, even if the lenses are slightly shifted by the position adjustment or the rotation adjustment and joined, the seating is performed by fixing to the base 16. It doesn't get worse. As will be described later, it is preferable to make the cylindrical lens 22a on the light source 1 side larger than the cylindrical lens 22b.

  By making the cross-sectional shape of the cylindrical lens 22a in the xy plane into a quadrangle, the bottom surface 22c of the cylindrical lens 22a can be brought into planar contact with the base 16, so that the beam shaping lens 22 can be stably formed. Can be placed. That is, since the rotation θ of the beam shaping lens 22 around the z-axis can be restricted, the beam shaping direction can be easily determined.

  Further, the beam shaping lens 22 needs to be positioned in the z direction and the x direction with respect to the light source 1 in order to obtain desired aberration performance. Since the bottom surface 22c of the cylindrical lens 22a is flatly rubbed against the base 16, there is an advantage that the position can be adjusted stably. By increasing the thickness of the cylindrical lens 22a in the z-direction, the area of the bottom surface 22c is increased, so that the position of the beam shaping lens 22 can be adjusted more stably.

  In addition, it is also possible to similarly implement by forming the cylindrical lens 22a in a circular cross-sectional shape and forming a flat portion (the bottom surface 22c) by cutting.

  If the ultraviolet curable adhesive 14 is applied between the bottom surface 22c and the base 16, the beam shaping lens 22 can be easily fixed by irradiating the ultraviolet ray after adjusting the position of the beam shaping lens 22. Generally, an adhesive expands or contracts due to a change in temperature. As shown in FIG. 5, the adhesive 14 applied on the xz plane (the plane perpendicular to the central axis of the cylindrical surface) expands and contracts uniformly in the x and z directions due to a temperature change. And movement in the z direction. However, the adhesive 14 expands and contracts in the y direction due to a temperature change, and moves the beam shaping lens 22 in the y direction. However, since the first surface 22i and the second surface 22o only move in the y direction, no change occurs in the optical characteristics. As described above, the second embodiment of the present invention has an advantageous advantage that the optical characteristics are not deteriorated by an environmental change such as a temperature change.

  Further, since the optical bench on which the optical components are mounted is made of metal or resin, expansion or contraction occurs due to a temperature change. Accordingly, the distance between the light source 1 and the beam shaping lens 22 fluctuates, and astigmatism occurs. In Embodiment 2 of the present invention, since the cylindrical lens 22a on the light source 1 side is enlarged, the fixing position of the beam shaping lens 22 by the adhesive 14 can be on the light source 1 side (closer to the first surface 22i). . Thus, since the distance between the light source 1 and the fixed position of the beam shaping lens 22 is shortened, expansion and contraction with respect to a temperature change can be reduced, and as a result, the effect of reducing fluctuation of astigmatism can be obtained. .

  As shown in FIG. 6, the cylindrical lens 22a may be pressed and fixed in the y direction (the center axis direction of the cylindrical surface) by the spring 15. By pressing only in the y direction, the beam shaping lens 22 does not move in the x and z directions even if the base 16 expands and contracts due to temperature changes. Since the surface 22i and the second surface 22o only move in the y direction, there is an advantageous effect that no change occurs in the optical characteristics. Also in this case, if the position where the beam shaping lens 22 is pressed by the spring 15 on the light source 1 side, the effect of reducing the fluctuation of astigmatism can be obtained.

  In the second embodiment of the present invention, the cylindrical lens 22a and the cylindrical lens 22b are made of glass. The beam shaping lens 22 itself expands and contracts due to a temperature change, and astigmatism occurs. Since glass has a smaller coefficient of thermal expansion than resin, variation in aberration due to temperature change can be suppressed to a small value.

(Embodiment 3)
Embodiment 3 of the present invention is shown in FIGS. 7A and 7B. The light source 1, the beam shaping lens 22, and their peripheral components are shown. The details of the beam shaping lens 22 are as described in the first and second embodiments.

  Generally, the light source 1 has a displacement of the light emitting point 21 of about 0.1 mm and an optical axis inclination of about 3 degrees due to a manufacturing error. In order to correct this, it is necessary to perform position adjustment and tilt adjustment of the light source 1. As shown in FIG. 7A, the light source 1 is fixed to the holder 11 by press-fitting or caulking, and the holder 11 is adjusted with respect to the adjustment plate 12 so as to correct the inclination of the optical axis of the light source 1. Is possible. The position of the adjustment plate 12 can be adjusted with respect to the optical bench 13 on which the optical components are mounted so that the position shift of the light emitting point 21 of the light source 1 is corrected. After the tilt adjustment and the position adjustment of the light source 1, the holder 11, the adjustment plate 12 and the optical bench 13 are fixed with the adhesive 24 and the adhesive 34.

  FIG. 7B shows a side view of the holder 11. The positional relationship between the light source 1 and the beam shaping lens 22 needs to be strictly adjusted, and it is preferable that the position change is small even if a temperature change occurs after the adjustment. If the light source 1 and the beam shaping lens 22 are held by separate holders and bonded to each other, there is a problem that the distance between the holders tends to fluctuate due to a temperature change. In the third embodiment of the present invention, since the beam shaping lens 22 and the light source 1 are mounted on the holder 11 which is a single member, the configuration is simple, so that the positional relationship changes even with environmental changes. Is small and good aberration characteristics can be maintained.

  FIG. 8 shows a case where the holder 11a on which the light source 1 and the beam shaping lens 22 are mounted is press-fitted into the adjustment plate 12a after the tilt adjustment. The adhesive 24 in FIG. 7A enters the gap between the holder 11 and the adjustment plate 12 because of the tilt adjustment structure, and expands and contracts due to a change in temperature, and easily changes the position of the light emitting point 21. As shown in FIG. 8, the influence of expansion and contraction of the adhesive can be eliminated by press-fitting, so that more stable performance can be maintained. It is to be noted that, instead of press-fitting, crimping or welding can be similarly performed.

(Embodiment 4)
FIG. 9 shows an optical head 39 according to the fourth embodiment of the present invention. The beam shaping lens 32 is any of those described in the first and second embodiments, and the collimating lens 4 is movable in the optical axis direction by a spherical aberration correction actuator 41.

  Generally, when there is an error in the thickness of the protective layer of the optical disc 10, spherical aberration occurs. This spherical aberration can be canceled out by the spherical aberration generated by making the beam incident on the objective lens 6 weakly divergent or weakly convergent.

  In the fourth conventional example, as shown in FIG. 19, after a collimating lens 504 converts the beam into a parallel beam, the beam is shaped by a beam shaping prism 502. In such an optical head 509, when the collimating lens 504 is moved in order to correct spherical aberration due to a thickness error of the protective layer of the optical disk 510, the beam diverges or converges. Astigmatism occurs. That is, it is difficult to correct spherical aberration. In the fourth embodiment, since the beam is shaped by the beam shaping lens 32 before the collimating lens 4, the spherical aberration can be corrected by moving the collimating lens 4 along the optical axis direction. As described above, the use of the beam shaping lens 32 having good aberration performance and stable against environmental changes enables spherical aberration correction by the collimator lens 4 for the first time. Further, since only the spherical aberration correcting actuator 41 is added, an advantageous effect that costs can be minimized can be obtained.

(Embodiment 5)
FIG. 10 shows an example of the overall configuration of an optical disk drive 107 as an optical information recording / reproducing apparatus. The optical disk 101 is fixed by being sandwiched between a turntable 102 and a clamper 103 and rotated by a motor (rotating system) 104. The optical head 100 described in any of Embodiments 1 to 4 is mounted on a traverse (transfer system) 105 so that light to be irradiated can move from the inner circumference to the outer circumference of the optical disc 101. The control circuit 106 performs focus control, tracking control, traverse control, motor rotation control, and the like based on a signal received from the optical head 100. It also reproduces information from the reproduction signal and sends out the recording signal to the optical head 100.

(Embodiment 6)
FIG. 11 shows an embodiment of a computer provided with the optical disk drive (optical information recording / reproducing device) described in Embodiment 5.

  11, a personal computer (computer) 110 includes an optical disk drive 107 according to the fifth embodiment, a keyboard 113 for inputting information, and a monitor 112 for displaying information.

  The computer provided with the optical disk drive of the fifth embodiment as an external storage device has an effect that information can be stably recorded or reproduced on different types of optical disks, and can be used for a wide range of applications. The optical disk drive takes advantage of its large capacity to make a backup of the hard disk in the computer, to make the media (optical disk) inexpensive and easy to carry, and to be able to read information with other optical disk drives. You can use it to exchange programs and data with people, or carry it around for yourself. In addition, it is possible to cope with reproduction / recording of existing media such as DVD and CD.

(Embodiment 7)
FIG. 12 shows an embodiment of an optical disk recorder (video recording / reproducing apparatus) including the optical disk drive (optical information recording / reproducing apparatus) described in Embodiment 5.

  In FIG. 12, an optical disk recorder 120 has a built-in optical disk drive 107 (not shown) according to the fifth embodiment, and is used by being connected to a monitor 121 for displaying recorded video.

  The optical disk recorder 120 including the optical disk drive 107 according to the fifth embodiment described above has an effect that video can be stably recorded or reproduced on different types of optical disks, and can be used for a wide range of applications. An optical disk recorder can record a video on a medium (optical disk) and reproduce it at any time. With optical discs, there is no need for rewinding work after recording or playback, as with tapes; chasing playback that plays back the beginning of a program while recording a program, or playback of a previously recorded program while recording a program Simultaneous recording and reproduction. Taking advantage of the fact that the media is inexpensive and easy to carry, and that there is compatibility that other optical disc recorders can read information from, the recorded video can be exchanged with a person or carried around for oneself. It also supports playback / recording of existing media such as DVDs and CDs.

  Here, the case where only an optical disk drive is provided has been described, but a hard disk may be built in, or a video tape recording / playback function may be built in. In this case, temporary saving and backup of the video can be easily performed.

(Embodiment 8)
FIG. 13 shows an embodiment of an optical disk player (video reproducing apparatus) provided with the optical disk drive (optical information recording / reproducing apparatus) described in the fifth embodiment.

  In FIG. 13, an optical disk player 131 having a liquid crystal monitor 130 has a built-in optical disk drive 107 (not shown) of the fifth embodiment, and can display a video recorded on an optical disk on the liquid crystal monitor 130. The optical disk player provided with the optical disk drive 107 according to the fifth embodiment has an effect that images of different types of optical disks can be stably reproduced and can be used for a wide range of applications.

  An optical disk player can play back a video recorded on a medium (optical disk) at any time. On an optical disc, unlike a tape, there is no need to perform a rewinding operation after reproduction, and an arbitrary place of a certain video can be accessed and reproduced. It also supports playback of existing media such as DVDs and CDs.

(Embodiment 9)
FIG. 14 shows an embodiment of a server provided with the optical disk drive (optical information recording / reproducing device) described in the fifth embodiment.

  14, a server 140 includes an optical disk drive 107 of the fifth embodiment, a monitor 142 for displaying information, and a keyboard 143 for inputting information, and is connected to a network 144.

  The server provided with the optical disk drive 107 of the fifth embodiment as an external storage device has an effect that information can be stably recorded or reproduced on different types of optical disks and can be used for a wide range of applications. The optical disk drive sends out information (images, audio, video, HTML documents, text documents, etc.) recorded on the optical disk in response to a request from the network 144 by utilizing its large capacity. Also, the information sent from the network is recorded at the requested location. In addition, since information recorded on existing media such as DVDs and CDs can also be reproduced, it is possible to transmit such information.

(Embodiment 10)
FIG. 15 shows an embodiment of a car navigation system including the optical disk drive (optical information recording / reproducing device) described in the fifth embodiment.

  In FIG. 15, a car navigation system 150 incorporates an optical disk drive 107 (not shown) according to the fifth embodiment, and is used by being connected to a liquid crystal monitor 151 for displaying terrain and destination information.

  The car navigation system including the optical disk drive 107 according to the fifth embodiment has an effect that images can be stably recorded or reproduced on different types of optical disks, and can be used for a wide range of purposes. The car navigation system 150 calculates a current position based on map information recorded on a medium (optical disk), information on a ground position determination system (GPS), a gyroscope, a speedometer, an odometer, and the like, and determines the position. Display on the LCD monitor. When a destination is input, an optimum route to the destination is determined based on map information and road information, and the route is displayed on an LCD monitor.

  By using a large-capacity optical disk for recording map information, a single disk can cover a wide area and provide fine road information. Further, information on restaurants, convenience stores, gas stations, and the like, which are attached to the vicinity of the road, can also be stored and provided on the optical disk at the same time. In addition, road information becomes old with time and does not match reality.However, since optical discs are compatible and media are inexpensive, it is possible to obtain the latest information by replacing it with a disc containing new road information. it can. In addition, in order to support reproduction / recording of existing media such as DVD and CD, it is possible to watch a movie or listen to music in a car.

  The present invention relates to an optical head, an optical information recording / reproducing apparatus for recording or reproducing information by irradiating an optical disk with light from the optical head, and a computer, a video recording / reproducing apparatus, a video reproducing apparatus, a server, and a car navigation using the same. Can be applied to the system.

FIG. 1 is a schematic diagram illustrating a configuration of an optical head according to a first embodiment of the present invention. 1 is a perspective view of a beam shaping lens according to a first embodiment of the present invention. Explanatory drawing of a spring press of a beam shaping lens according to Embodiment 1 of the present invention. Explanatory drawing of another spring holder of the beam shaping lens according to the first embodiment. Explanatory drawing of another base mounting the beam shaping lens according to the first embodiment. Explanatory drawing of still another base on which the beam shaping lens according to the first embodiment is mounted. FIG. 4 is a schematic diagram illustrating a configuration of an optical head according to a second embodiment of the present invention. FIG. 3 is a perspective view of a beam shaping lens according to Embodiment 2 of the present invention. Explanatory drawing of a spring press of a beam shaping lens according to a second embodiment of the present invention. Explanatory drawing mounting a beam shaping lens according to Embodiment 3 of the present invention. Explanatory drawing mounting a beam shaping lens according to Embodiment 3 of the present invention. 4 is a schematic diagram showing a configuration of an optical head according to Embodiment 4 of the present invention. Schematic diagram of an optical disk drive using the optical head of the present invention External view of a personal computer using the optical disk drive of the present invention External view of an optical disk recorder using the optical disk drive of the present invention External view of an optical disk player using the optical disk drive of the present invention External view of server using optical disk drive of the present invention External view of a car navigation system using the optical disk drive of the present invention FIG. 1 is a schematic diagram showing a configuration of a first conventional optical head. FIG. 3 is a schematic diagram illustrating a second conventional cylindrical lens. Schematic diagram for explaining a beam shaping lens of a third conventional example Schematic diagram for explaining a fourth conventional optical head

Explanation of reference numerals

DESCRIPTION OF SYMBOLS 1 Light source 2, 22 Beam shaping lens 3 Branching prism 4 Collimating lens 5 Mirror 6 Objective lens 7 Detecting lens 8 Detector 9, 29, 39 Optical head 10 Optical disk 11 Holder 12 Adjustment plate 13 Optical table 14, 24, 34 Adhesive 15 Spring 16 Base 21 Light emitting point 41 Spherical aberration correction actuator 61 Objective lens actuator 100 Optical head 101 Optical disk 102 Turntable 103 Clamper 104 Motor 105 Traverse 106 Control circuit 107 Optical disk drive 110 Personal computer 111 Optical disk drive 120 Optical disk recorder 131 Optical disk player 140 Server 141 Optical disk Drive 144 Network 150 Car navigation system

Claims (31)

A light source,
A beam shaping lens for shaping an elliptical divergent beam emitted from the light source into a substantially circular divergent beam,
A collimating lens that converts the substantially circular divergent beam into a substantially parallel beam,
An objective lens for focusing the substantially parallel beam on an optical information recording medium;
An optical head comprising a detector for detecting a beam reflected by the optical information recording medium,
An optical head, wherein the beam shaping lens has a pair of cylindrical surfaces curved in the same direction, one of the cylindrical surfaces is an aspheric surface, and the other cylindrical surface is a spherical surface.   2. The optical head according to claim 1, wherein the beam shaping lens has an aspherical cylindrical surface near the light source and a spherical cylindrical surface far from the light source.   2. The optical head according to claim 1, wherein the beam shaping lens has a square cross section perpendicular to the optical axis.   The optical head according to claim 1, wherein the material of the beam shaping lens is glass.   The optical head according to claim 1, wherein a fixed position between the base on which the beam shaping lens is mounted and the beam shaping lens is closer to the light source than a center of the beam shaping lens.   2. The optical head according to claim 1, wherein the base on which the beam shaping lens is mounted and the beam shaping lens are fixed on a plane perpendicular to a central axis of a cylindrical surface of the beam shaping lens.   The optical head according to claim 1, wherein the base on which the beam shaping lens is mounted and the beam shaping lens are pressed by a spring that presses along a central axis direction of a cylindrical surface of the beam shaping lens.   2. The optical head according to claim 1, wherein the beam shaping lens includes two cylindrical lenses, and the two cylindrical lenses are joined to each other.   9. The optical head according to claim 8, wherein a surface where the two cylindrical lenses are joined is a flat surface.   9. The optical head according to claim 8, wherein the two cylindrical lenses have different cross-sectional sizes perpendicular to the optical axis.   The optical head according to claim 10, wherein a size of a cross section of the two cylindrical lenses perpendicular to an optical axis is larger in a cylindrical lens close to the light source.   9. The optical head according to claim 8, wherein the two cylindrical lenses have different thicknesses along the optical axis. 13. The optical head according to claim 12, wherein the thickness of the two cylindrical lenses along the optical axis is greater for a cylindrical lens closer to the light source.   The optical head according to claim 1, wherein the light source and the beam shaping lens are fixed to a same holder.   15. The optical head according to claim 14, wherein the holder has a tilt adjustment mechanism for correcting an optical axis tilt of the light source.   15. The optical head according to claim 14, wherein the holder has a position adjusting mechanism for correcting a position error of a light emitting point of the light source.   15. The optical head according to claim 14, wherein the holder is pressed into an optical table of the optical head by a press.   15. The optical head according to claim 14, wherein the holder is fixed by caulking to an optical table of the optical head.   The optical head according to claim 14, wherein the holder is welded to an optical table of the optical head.   2. The optical head according to claim 1, wherein the collimating lens is movable in an optical axis direction. A light source,
A beam shaping lens for shaping an elliptical divergent beam emitted from the light source into a substantially circular divergent beam,
A collimating lens that converts the substantially circular divergent beam into a substantially parallel beam,
An objective lens for focusing the substantially parallel beam on an optical information recording medium;
An optical head comprising a detector for detecting a beam reflected by the optical information recording medium,
An optical head, wherein a fixed position of the base on which the beam shaping lens is mounted and the beam shaping lens is closer to the light source than the center of the beam shaping lens.   22. The optical head according to claim 21, further comprising an adhesive applied only to a side of the beam shaping lens close to the light source to bond the beam shaping lens and the base.   22. The optical head according to claim 21, further comprising an elastic body that presses the beam shaping lens on a side of the beam shaping lens near the light source.   22. The optical head according to claim 21, wherein the base has a convex shape with respect to the beam shaping lens on a side near the light source.   22. The optical head according to claim 21, wherein the base has a concave shape with respect to the beam shaping lens between a side near and far from the light source. An optical head according to claim 1,
A rotation system or a transfer system for relatively moving the optical head and the optical information recording medium,
An optical information recording / reproducing apparatus comprising: a control circuit that controls the optical head, the rotation system, and the transport system based on a signal obtained from the optical head.   A computer comprising the optical information recording / reproducing device according to claim 26 as an external storage device.   An image recording / reproducing apparatus comprising the optical information recording / reproducing apparatus according to claim 26, wherein the apparatus records and reproduces an image on an optical information recording medium.   An image reproducing apparatus comprising the optical information recording / reproducing apparatus according to claim 26 and reproducing an image from an optical information recording medium.   A server comprising the optical information recording / reproducing device according to claim 26 as an external storage device. A car navigation system comprising the optical information recording / reproducing device according to claim 26 as an external storage device.

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