JP2007323754A - Optical pickup device, optical element, and objective lens drive device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve simultaneously reduction in thickness of an optical pickup provided with a rising mirror and high rigidity of an objective lens drive unit. <P>SOLUTION: Rising mirrors 1, 2 are formed to have narrower width near objective lenses 3, 4. Then, reinforcement structure 12a is provided at a part opposing to a part having the narrow width of the rising mirrors 1, 2 (notched plane 1a) in a lens holder 12. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an optical pickup device used in an apparatus for recording / reproducing an optical disc, an optical element provided in the optical pickup device, and an objective lens driving device.

  2. Description of the Related Art Conventionally, optical information recording apparatuses that perform recording and reproduction on a disk-shaped recording medium (optical disk) using light (laser light) have been widely used. As such an optical disk, BD (Blu-ray Disc) and the like have been developed in addition to CD and DVD.

  By the way, in order to perform good recording / reproduction with respect to an optical disc such as CD, DVD, and BD, light emitted from a laser light source is incident on an objective lens to form a minute beam spot on the optical disc, and the spot shape It is necessary to follow the desired recording track while maintaining the above.

  In order to achieve this, conventionally, a technology is provided in which an upright mirror is provided that is disposed in the vicinity of the objective lens, reflects the light incident from the light source, changes its optical axis direction, and enters the objective lens. Is used. Patent Document 1 describes an example of a rising mirror.

  FIG. 9 is a perspective view of a rising mirror described in Patent Document 1. FIG. FIG. 10A is a cross-sectional view of the vicinity of the rising mirror in the optical pickup including the rising mirror, and FIG. 10B is an arrow view seen from the direction A shown in FIG. FIG.

As shown in FIGS. 9 and 10A, the rising mirrors 130 and 131 are directly below the objective lenses 132 and 133, respectively, and their respective incident surfaces are inclined 45 degrees with respect to the optical axis of the light from the laser light source. In this state, the light from the laser light source is reflected and guided to the objective lenses 132 and 133. As shown in FIG. 10B, the rising mirrors 130 and 131 are rectangular when viewed from the direction in which the light from the laser light source enters. That is, in the rising mirrors 130 and 131, the width in the direction perpendicular to the incident light and the outgoing light with respect to each mirror is constant regardless of the position.
JP 2005-174485 A (published June 30, 2005)

  In recent years, there has been a demand for higher transfer rates for optical disc recording / reproducing apparatuses. In order to cope with the higher transfer rate, a characteristic capable of controlling the objective lens at high speed, that is, a wideband frequency characteristic is desired for the objective lens driving apparatus mounted on the optical disc recording / reproducing apparatus.

  In order to realize the wide band of the frequency characteristics, it is better that the resonance frequency of the objective lens driving unit including the objective lens and the objective lens holder is higher. In order to increase the resonance frequency of the objective lens driving unit, it is necessary to increase the rigidity of the objective lens driving unit.

  However, when increasing the transfer rate, there is a problem that the size of the optical pickup device is increased. That is, as shown in FIG. 10A, the thickness in the focus direction in the optical pickup device is the thickness of the rising mirrors 130 and 131 and the thickness of the periphery of the objective lens in the holding member 135 of the objective lenses 132 and 133. Depends heavily on For this reason, in order to reduce the thickness of the optical pickup device, it is necessary to reduce the thickness of at least the periphery of the objective lens in the holding member 135. However, if the peripheral portion of the objective lens in the holding member 135 is thinned, the rigidity of the objective lens driving unit is lowered.

  Therefore, the conventional optical pickup provided with the rising mirror cannot solve the problems of thinning the optical pickup and increasing the transfer rate (high rigidity) at the same time.

  In particular, when using a configuration in which a plurality of objective lenses are integrally held by a single drive unit for recording and reproducing a plurality of types of discs having different wavelengths of laser light to be used, such as CD, DVD, and BD, depending on the type of optical disc Since the working distance of the objective lens is different, it is necessary to secure a wide movable range (for example, about ± 1 mm) of the objective lens driving unit. However, since the objective lens drive unit needs to have a shape that does not interfere with the rising mirror during driving, in order to form a thin objective lens drive device, the objective lens peripheral part of the objective lens drive unit is considerably thinned. As a result, it is more difficult to ensure the rigidity of the objective lens driving unit. Accordingly, the high-order resonance frequency in the frequency characteristic of the objective lens driving unit is lowered, and it becomes impossible to cope with high-speed recording / reproduction.

  The present invention has been made in view of the above problems, and an object of the present invention is to simultaneously realize a reduction in the thickness of an optical pickup provided with a rising mirror and an increase in rigidity of an objective lens driving unit.

  In order to solve the above problems, an optical pickup device of the present invention is provided with a light source, an objective lens, and the objective lens at a predetermined interval, and reflects and reflects incident light from the light source. An optical pickup comprising: an optical element that causes light to enter the objective lens; and a drive unit that holds the objective lens so as to be movable relative to the optical element. At least a part thereof includes a cross-sectional reduced portion whose cross-sectional area perpendicular to the reflected light is smaller as it approaches the drive unit, and at a position facing the cross-sectional reduced portion in the drive unit. A reinforcement structure for increasing the rigidity of the drive unit is provided.

  According to said structure, the cross-sectional reduction part by which the area of the cross section perpendicular | vertical to the said reflected light is small is provided in at least one part of the opposing parts with respect to the said drive unit in the said optical element as it approaches the said drive unit. ing. Thereby, for example, even when the distance between the drive unit and the optical element is constant, a region where the drive unit can be formed is widened. And according to said structure, in order to increase the rigidity of this drive unit in the area | region where the drive unit could be formed more widely than this conventionally, ie, the position facing the said cross-sectional reduction part in the said drive unit. A reinforcing structure is provided. Thus, the drive unit is provided with a reinforcing structure without increasing the distance between the drive unit and the optical element, and without increasing the thickness of the cross section including the drive unit and the optical element in the optical pickup device. be able to. Thereby, it is possible to simultaneously realize the thinning of the optical pickup device and the high rigidity of the drive unit. Also, by increasing the rigidity of the drive unit, the natural frequency (higher order resonance frequency) of this drive unit can be increased, so that oscillation of servo (for example, radial servo and focus servo) is suppressed and stable servo is performed. be able to.

  The drive unit includes a lens holding unit that holds the objective lens, and a peripheral part that is provided at a position farther from the optical axis of the incident light than the lens holding unit, and holds the lens holding unit, The thickness in the first direction parallel to the optical axis of the incident light to the objective lens in the lens holding portion is thinner than the thickness in the first direction at the peripheral edge, and the optical element is the lens holding portion. The reinforcing structure may be disposed at a contact portion between the lens holding portion and the peripheral portion.

  According to said structure, the thickness of the 1st direction parallel to the optical axis of the incident light to the objective lens in a lens holding | maintenance part is thinner than the thickness to the 1st direction in a peripheral part. For this reason, by disposing the optical element so as to face the lens holding part and the peripheral part, a part of the optical element enters the space generated when the lens holding part is thinner than the peripheral part. Optical elements and drive units can be arranged. Therefore, the thickness of the cross section including the optical element and the drive unit in the optical pickup device can be reduced without increasing the distance between the lens holding portion and the optical element.

  Moreover, according to said structure, the reinforcement structure is provided in the contact part of a lens holding | maintenance part and a peripheral part. Thereby, it is possible to simultaneously realize the thinning of the optical pickup device and the high rigidity of the drive unit. Further, by increasing the rigidity of the drive unit, the natural frequency of the drive unit can be increased, so that servo oscillation can be suppressed and stable servo can be performed.

  In addition, the reinforcing structure may have a cross-sectional shape that abuts a surface facing the optical element in the lens holding portion and a surface facing the optical element in the peripheral edge.

  According to said structure, by forming the said reinforcement structure so that it may have a cross-sectional shape contact | abutted to the opposing surface with respect to the said optical element in the said lens holding part, and the opposing surface with respect to the said optical element in the said peripheral part, The rigidity of the drive unit can be effectively increased.

  The reinforcing structure may be formed integrally with at least a part of the drive unit. For example, the drive unit may be thickened at a position facing the cross-sectional reduction portion.

  According to said structure, while forming a reinforcement structure integrally with at least one part of the said drive unit, while reducing a number of parts, a manufacturing process can be simplified.

  The optical element includes an incident surface inclined by approximately 45 degrees with respect to the optical axis of the incident light, and the optical axis direction of the incident light incident on the incident surface is converted by approximately 90 degrees. The structure which injects into the said objective lens may be sufficient. The inclination angle of the incident surface and the angle for converting the optical axis direction are not necessarily 45 degrees and 90 degrees, and may include an attachment error (for example, ± 1 degree).

  According to the above configuration, each member provided in the optical pickup device can be efficiently arranged by converting the optical axis of the light emitted from the light source by 90 ° ± 10 and causing it to enter the objective lens. Therefore, it is possible to reduce the size of the optical pickup device.

  Further, the cross-sectional reduction part may be provided at an end of the optical element on the emission direction side of the reflected light. Further, the cross-sectional reduction portion has a configuration in which, for example, when viewed from the direction in which the incident light is incident, a width in a direction perpendicular to the reflected light becomes narrower toward an emission direction of the reflected light. There may be.

  According to said structure, since the cross-sectional reduction part is provided in the edge part of the emission direction side of the said reflected light in the said optical element, the said reinforcement structure can be provided in the peripheral part of the objective lens in a drive unit. . Therefore, when reducing the thickness of the optical pickup device, it is possible to provide a reinforcing structure in a portion of the drive unit that needs to be most thinned, and the rigidity of the drive unit can be increased efficiently.

  The optical element has a rectangular outer shape viewed from the direction in which the incident light is incident, and at least one of corners located on the emission direction side of the reflected light in the rectangular outer shape, The shape may be chamfered. According to said structure, an optical element can be formed easily.

  The optical element may have an outer shape viewed from a direction in which the incident light is incident and axially symmetric with respect to an axis parallel to the optical axis of the reflected light.

  According to said structure, since the shape of a drive unit can be made axially symmetrical, control of the gravity center of a drive unit becomes easy, and the influence of the unnecessary resonance resulting from the shift | offset | difference of a gravity center and a power point can be reduced.

  Moreover, the structure which the outer shape of the light beam of the said incident light may be settled in the incident surface of the said incident light in the said optical element may be sufficient.

  According to said structure, since the external shape of the light beam of the said incident light is settled in the incident surface of the said incident light in the said optical element, the utilization efficiency of incident light can be improved.

  In addition, a second light source that emits light having a wavelength different from that of the light source, a second objective lens, and a second light that reflects the light emitted from the second light source and causes reflected light to enter the second objective lens. The optical element may be configured to transmit incident light from the second light source and to enter the second optical element.

  According to the configuration described above, since a plurality of light sources that emit light having different wavelengths are provided, it is possible to perform recording and / or reproduction with respect to a plurality of types of optical disks. Further, in the case of a configuration capable of recording / reproducing a plurality of types of optical discs, the working distance of the objective lens differs depending on the type of the optical disc, so that it is necessary to secure a particularly wide movable range of the drive unit. According to the configuration, the drive unit and the optical element are sufficiently spaced from each other, and the drive unit has a reinforcing structure without increasing the thickness of the cross section including the drive unit and the optical element in the optical pickup device. Can be provided.

  Further, the outer shape of the light beam transmitted through the optical element may be configured to be within an emission surface of the transmitted light in the optical element.

  According to said structure, since the external shape of the light beam which permeate | transmits the said optical element is settled in the output surface of the said transmitted light in the said optical element, the utilization efficiency of this emitted light can be improved.

  Further, the configuration may be such that an outer shape of a light beam of incident light that passes through the optical element and enters the second optical element is within an incident surface of the second optical element.

  According to said structure, since the external shape of the light beam of the incident light which permeate | transmits the said optical element and injects into the said 2nd optical element is settled in the entrance plane of the said 2nd optical element, it injects into this 2nd optical element. It is possible to improve the light use efficiency.

  Further, at least a part of the second optical element facing the drive unit includes a cross-sectional reduction portion in which a cross-sectional area perpendicular to the reflected light becomes smaller as the drive unit is approached. It is good.

  According to said structure, both the said optical element and the said 2nd optical element are equipped with the said cross-sectional reduction part. Therefore, since the reinforcing structure provided in the drive unit can be increased in size or increased, the cross section including the drive unit and the optical element in the optical pickup device without increasing the distance between the drive unit and the optical element. The rigidity of the drive unit can be further increased without increasing the thickness of the drive unit.

  In order to solve the above problems, an optical element of the present invention is an optical element that is provided in an optical pickup device, reflects incident light from a light source, and causes reflected light to enter an objective lens. A feature of the present invention is that an end portion on the emission direction side is provided with a cross-sectional reduction portion in which the area of the cross section perpendicular to the reflected light decreases toward the emission direction of the reflected light.

  According to said structure, the cross-section reduction | decrease part in which the area of the cross section perpendicular | vertical to this reflected light is provided in the edge part of the said emission direction side of said reflected light toward the exit direction of this reflected light is provided. Therefore, the installation space for the optical element can be reduced as compared with the configuration without the cross-sectional reduction portion. Thereby, the design freedom degree of the drive unit which hold | maintains an objective lens so that a movement is possible only by this reduced installation space can be increased. In addition, it is possible to provide a reinforcing structure for increasing the rigidity of the drive unit at a position facing the reduced section in the drive unit. That is, the drive unit can be provided with a reinforcing structure without increasing the distance between the drive unit and the optical element and without increasing the thickness of the cross section including the drive unit and the optical element in the optical pickup device. it can. Thereby, it is possible to simultaneously realize the thinning of the optical pickup device and the high rigidity of the drive unit.

  In addition, the external shape seen from the incident direction of the incident light may be a shape in which at least a part of a rectangular shape is chamfered. According to said structure, an optical element can be formed easily.

  Moreover, the external shape seen from the direction in which the incident light enters may be axially symmetric with respect to an axis parallel to the optical axis of the reflected light.

  According to said structure, since the shape of a drive unit can be made axially symmetrical, control of the gravity center of a drive unit becomes easy, and the influence of the unnecessary resonance resulting from the shift | offset | difference of a gravity center and a power point can be reduced.

  Moreover, the structure which reflects the light of a 1st wavelength range and permeate | transmits the light of a 2nd wavelength range may be sufficient.

  According to the above configuration, for example, when an optical pickup device including a plurality of light sources and a plurality of objective lenses provided corresponding to the respective light sources is provided, the arrangement of each member included in the optical pickup device is arranged. The optical pickup device can be reduced in size efficiently.

  In order to solve the above problems, an objective lens holding device of the present invention includes a light source, an objective lens, and an optical element that reflects incident light from the light source and causes reflected light to enter the objective lens. An objective lens holding device that is provided in an optical pickup device and holds the objective lens so as to be movable relative to the optical element in a state of being spaced apart from the optical element by the objective lens. A lens holding part for holding the lens holding part, and a peripheral edge part for holding the lens holding part at a position farther from the optical axis of the incident light than the lens holding part. The thickness in the first direction parallel to the optical axis of the incident light is thinner than the thickness in the first direction at the peripheral edge, and a reinforcing structure is provided at the contact portion between the lens holding portion and the peripheral edge. Have It is characterized in.

  According to said structure, the thickness of the 1st direction parallel to the optical axis of the incident light to the said objective lens in the said lens holding part is thinner than the thickness to the said 1st direction in the said peripheral part. . For this reason, the optical element and the objective lens holding device can be arranged so that a part of the optical element enters a space generated when the lens holding part is thinner than the peripheral part. Therefore, the thickness of the cross section including the optical element and the objective lens holding device in the optical pickup device can be reduced without increasing the distance between the lens holding portion and the optical element.

  Further, a reinforcing structure is provided at a contact portion between the lens holding portion and the peripheral portion. Thereby, it is possible to simultaneously realize the thinning of the optical pickup device and the high rigidity of the drive unit. Further, by increasing the rigidity of the drive unit, the natural frequency of the drive unit can be increased, so that servo oscillation can be suppressed and stable servo can be performed.

  In addition, the reinforcing structure may have a cross-sectional shape that abuts a surface facing the optical element in the lens holding portion and a surface facing the optical element in the peripheral edge.

  According to said structure, by forming the said reinforcement structure so that it may have a cross-sectional shape contact | abutted to the opposing surface with respect to the said optical element in the said lens holding part, and the opposing surface with respect to the said optical element in the said peripheral part, The rigidity of the drive unit can be effectively increased.

  The reinforcing structure may be formed integrally with at least one of the lens holding portion and the peripheral portion. For example, the thickness of at least one of the lens holding part or the peripheral part may be increased.

  According to said structure, while forming a reinforcement structure integrally with at least one of the said lens holding | maintenance part or the said peripheral part, while reducing a number of parts, a manufacturing process can be simplified.

  As described above, in the optical pickup device of the present invention, at least a part of the optical element facing the drive unit has a smaller cross-sectional area perpendicular to the reflected light as it approaches the drive unit. A reinforcing structure for increasing the rigidity of the drive unit is provided at a position facing the cross-sectional reduced portion of the drive unit.

  Therefore, it is possible to simultaneously realize the thinning of the optical pickup device and the high rigidity of the drive unit.

  In addition, the optical element of the present invention includes a cross-sectional reduction portion in which the area of the cross section perpendicular to the reflected light becomes smaller toward the emission direction of the reflected light.

  Therefore, the degree of freedom in designing the drive unit that holds the objective lens movably can be increased. In addition, a reinforcing structure for increasing the rigidity of the drive unit can be provided at a position facing the cross-sectional reduction portion of the drive unit. Thereby, it is possible to simultaneously realize the thinning of the optical pickup device and the high rigidity of the drive unit.

  In the objective lens holding device of the present invention, the thickness in the first direction parallel to the optical axis of the light incident on the objective lens in the lens holding portion is thinner than the thickness in the first direction at the peripheral edge portion, A reinforcing structure is provided at a contact portion between the lens holding portion and the peripheral edge portion.

  Therefore, it is possible to simultaneously realize the thinning of the optical pickup device and the high rigidity of the drive unit.

  An embodiment of the present invention will be described. 2A is a top view of the optical pickup device 100 according to the present embodiment, and FIG. 2B is a cross-sectional view of the optical pickup device 100 as viewed from the side. The optical pickup device 100 is provided in an optical disc recording / reproducing apparatus, and performs recording and reproduction on the optical disc. Further, this recording / reproducing apparatus can perform recording / reproducing with respect to a plurality of types of optical discs such as a CD (CD-ROM, CD-R, CD-RW), DVD (DVD-ROM, DVD-R, DVD-RW), and BD. It is like that. However, the configuration of the recording / reproducing apparatus is not limited to this, and for example, one of recording and reproduction may be performed.

  As shown in FIG. 2B, the optical pickup device 100 is supported by shafts 121 and 122 provided in the recording / reproducing device, and can move in the radial direction of the optical disc 140 along the shafts 121 and 122. ing.

  As shown in FIGS. 2A and 2B, the optical pickup device 100 includes light sources 101a and 101b, holograms 102a and 102b, photodetectors 103a and 103b, a prism 108, a collimator lens 104, and a movable side correction lens. (Correction lens) 105, fixed-side correction lens 106, rising mirrors 1 and 2, objective lenses 3 and 4, objective lens driving device 30, motor (drive source) 110, gear unit 111, and support for these optical components A housing 120 is provided.

  The light source 101a is a laser diode (semiconductor laser) that emits laser light having a wavelength of 405 nm. The light source 101b includes a laser diode that emits laser light having a wavelength of 660 nm and a laser diode that emits laser light having a wavelength of 780 nm. The configuration of the light sources 101a and 101b and the wavelength of the emitted light from each light source are not limited to this.

  The holograms 102a and 102b diffract the light reflected and returned by the optical disc 140 and guide it to the light detection devices 103a and 103b. The light detection devices 103a and 103b receive the signals diffracted by the holograms 102a and 102b. It receives light.

  In the optical pickup device 100, the light generated by the light source 101 a or 101 b passes through the hologram 102 a or 102 b as 0th-order diffracted light, and further passes through the collimator lens 104 via the prism 108 to become a parallel light beam. The light that has passed through the collimator lens 104 then passes through the movable side correction lens 105 and the fixed side correction lens 106. At this time, the movable side correction lens 105 is moved, and the distance between the movable side correction lens 105 and the fixed side correction lens 106 is changed, so that light passing through the movable side correction lens 105 and the fixed side correction lens 106 is parallelized. Can be converted to light, convergent light, or divergent light. Thereby, the spherical aberration on the recording surface 141 of the optical disc 140 can be corrected.

  The light passing through the fixed side correction lens 106 is bent by 90 ° by the rising mirrors 1 and 2, then condensed by the objective lenses 3 and 4, and irradiated onto the optical disc 140. The light applied to the optical disc 140 passes through the optical transparent layer of the optical disc 140 and is condensed on the recording surface 141 of the optical disc 140. The objective lenses 3 and 4 are subjected to focus servo and radial servo by the objective lens driving device 30 so that the positional relationship between the optical disk 140 and the objective lenses 3 and 4 is constant even when there is a surface shake or disturbance of the optical disk 140. The beam spot on the recording surface 141 is kept in a substantially constant shape.

  Thereafter, the reflected light from the recording surface 141 of the optical disc 140 follows the reverse optical path, and passes through the objective lenses 3 and 4, the rising mirrors 1 and 2, the fixed correction lens 106, the movable correction lens 105, and the collimating lens 104. pass. The reflected light is diffracted when it reaches the holograms 102a and 102b via the prism 108. The photodetectors 103a and 103b detect this diffracted light. Based on this detection light, information recorded on the optical disc 140 is reproduced. A servo control unit (not shown) provided in the recording / reproducing device generates a focus servo signal, a radial servo signal, and a spherical aberration signal based on the detection light detected by the light detection devices 103a and 103b. A servo current corresponding to the servo signal is supplied from a power supply means (not shown) to the objective lens driving device 30, and the moving operation of the movable correction lens 105 is controlled according to the spherical aberration signal.

  FIG. 3 is a perspective view of the objective lens driving device 30. As shown in this figure, the objective lens drive device 30 includes a drive unit 31, a fixed unit 32, and a support member 16.

  The support member 16 is made of a rod-shaped elastic member, and one end side is fixed to the fixed unit 32 and the other end side is fixed to the drive unit 31. Thereby, the position of the drive unit 31 can be moved relative to the fixed unit 32 by a focus servo and a radial servo described later.

  The support member 16 is made of a conductive material, and transmits a servo signal supplied from the power supply means to the drive unit 31. In the present embodiment, a total of six support members 16 are provided, and each support member 16 supplies servo signals to different drive coils (a focus direction drive coil 13 and a radial direction drive coil 14 described later). It has become.

  The drive unit 31 includes objective lenses 3 and 4, a lens holder 12, a focus direction drive coil 13, a radial direction drive coil 14, and a relay substrate 15.

  The objective lenses 3 and 4 are held at the approximate center of the drive unit 31 by a lens holder 12 having a substantially rectangular parallelepiped shape. The material of the lens holder 12 is not particularly limited, but polyphenylene sulfide (PPS) resin is used in this embodiment.

  The focus direction drive coils 13 are respectively provided on a pair of opposing side surfaces of the lens holder 12.

  The radial direction drive coil 14 is provided so as to sandwich each focus direction drive coil 13 from both sides. Therefore, the drive unit 31 includes a total of two focus direction drive coils 13 and a total of four radial direction drive coils 14.

  The relay board 15 is provided on each side surface of each focus direction drive coil 13. Note that three support members 16 are attached to each relay substrate 15. Thus, the drive unit 31 is supported so as to be relatively displaceable with respect to the fixed unit 32.

  The fixed unit 32 includes a magnet 17, a dump block 20, an FPC 19, and a base plate 18.

  The magnet 17 is disposed so as to sandwich the focus direction drive coil 13 and the radial direction drive coils 14, 14 at a predetermined interval from both sides.

  The dump block 20 has a penetrating portion through which the support member 16 penetrates, and the penetrating portion is filled with a damping agent (not shown). Thereby, the peak amount of resonance caused by the support member 16 is reduced.

  The FPC 19 transmits a servo current supplied from the power supply means. The servo current supplied via the FPC 19 is fed to the focus direction drive coil 13 and the radial direction drive coil 14 via the support member 16 and the relay substrate 15. As a result, an electromagnetic force is generated by the servo current supplied to each coil and the magnetic flux from the magnet 17, and the drive unit 31 is driven (servo-driven) in the focus direction and the radial direction.

  FIG. 4A is a side view of the rising mirrors 1 and 2 and the objective lenses 3 and 4 as seen from a direction perpendicular to the incident light and the outgoing light with respect to the rising mirrors 1 and 2. 4B is a side view of the rising mirrors 1 and 2 and the objective lenses 3 and 4 as seen from the direction in which light from the light sources 101a and 101b enters the rising mirrors 1 and 2. FIG. .

  The rising mirror 1 has a function of reflecting incident light (light having a predetermined wavelength range) from the light source 101a and transmitting incident light (light outside the predetermined wavelength range) from the light source 101b. .

  As shown in FIG. 4A, the rising mirror 1 has an incident surface 1b with respect to an optical axis 5 of incident light from a light source 101a (not shown) and an optical axis 7 of incident light from the light source 101b. It is arranged in an inclined state of about 45 degrees. As a result, the rising mirror 1 reflects incident light from the light source 101 a, changes its optical axis 5 by 90 degrees, converts it to the optical axis 6, and guides this reflected light to the objective lens 3. Further, the rising mirror 1 transmits incident light (optical axis 7) from the light source 101b and emits it as outgoing light of the optical axis 8 in the direction of the rising mirror 2. Further, the rising mirror 2 reflects incident light from the light source 101b, changes its optical axis 8 by 90 degrees and converts it into the optical axis 9, and guides this reflected light to the objective lens 4.

  As shown in FIG. 4B, the light beam diameter 10 of the incident light from the light source 101a and the light beam diameter 11 of the incident light from the light source 101b are both within the incident surface (outer shape incident surface) 1b of the rising mirror 1. These light beams do not protrude from the incident surface 1b. The diameter of the light beam emitted from the light source 101b and transmitted through the rising mirror 1 is within the emission surface 1c of the rising mirror 1, and passes through the rising mirror 1 and enters the rising mirror 2. The diameter of the light beam is within the incident surface 2 b of the rising mirror 2. In addition, it is preferable that an appropriate clearance is provided between the outer shape of the incident surface 1 b and the light beam diameter 10 and the light beam diameter 11 in order to absorb the mounting error of the rising mirror 1. Similarly, between the outer shape of the exit surface 1c of the rising mirror 1 and the beam diameter of the outgoing light transmitted through the rising mirror 1, and the outer shape of the incident surface 2b of the rising mirror 2 and the incident light incident on the rising mirror 2 It is preferable that an appropriate clearance is provided between the light beam diameters.

  As shown in FIGS. 4 (a) and 4 (b), the objective mirrors 3 and 4 side (lens holder 12 side) of the rising mirrors 1 and 2 are the objective lenses 3 and 4 (lens holder). The width becomes narrower as it approaches 12). That is, the end portions of the rising mirrors 1 and 2 on the objective lens 3 and 4 side are chamfered to form notched surfaces 1a and 2a. Thereby, in this embodiment, it is possible to provide a reinforcement structure in a portion of the lens holder 12 facing the notch surface 1a.

  This point will be described in more detail. FIG. 1A is a perspective view showing a state in which the objective lens driving device 30 is provided in the optical pickup device 100. In this figure, the drive unit 31, the support member 16, and the rising mirrors 1 and 2 are extracted, and the other members are omitted. FIG. 1B is a diagram showing a state in which the drive unit 31 and the rising mirror 1 are viewed from the incident direction of light from the light sources 101a and 101b. FIG. 5 is a perspective view in which the objective lenses 3 and 4 and the rising mirrors 1 and 2 are extracted from the perspective view shown in FIG.

  As shown in FIG. 1 (b), the drive unit 31 includes a recess 12b in which the thickness of the periphery of the objective lenses 3 and 4 is thinner than the peripheral edge thereof. A part of the rising mirrors 1 and 2 is disposed so as to enter the concave portion 12b with a predetermined distance from the drive unit 31. As a result, the thickness of the portion of the optical pickup device 100 where the lens holder 12 and the rising mirrors 1 and 2 are provided is thinner than when the recess 12b is not provided. In this embodiment, the recess 12b is provided in the drive unit 31, but the shape of the drive unit 31 is not limited to this, and the position of the drive unit 31 is raised by the focus servo and the radial servo. The drive unit 31 and the rising mirrors 1 and 2 are spaced apart from each other even if they change relative to each other. Any shape can be used as long as the thickness of the optical pickup device 100 can be reduced. For example, the portion including the rising mirrors 1 and 2 in the optical pickup device 100 including the rising mirror is obtained by making the facing portion of the driving unit 31 facing the rising mirror 1 and 2 thinner than the peripheral edge of the facing portion. Can be made thinner.

  Further, as shown in FIG. 1B, the width of the part of the rising mirrors 1 and 2 on the objective lens 3 and 4 side (lens holder 12 side) becomes closer to the objective lens 3 and 4 (lens holder 12). It is narrower. A thick portion (reinforcing structure) 12a is provided in a portion of the lens holder 12 that faces the portion (notched surfaces 1a, 2a) where the width of the rising mirrors 1, 2 is narrowed.

  More specifically, as shown in FIG. 1B, when the rising mirrors 1 and 2 are viewed from the direction in which the light from the light sources 101a and 101b is incident, The end portions on the side of the lenses 3 and 4 are chamfered to form notched surfaces 1a and 2a. Then, an even angle portion in the concave portion 12b of the drive unit 31 (a contact portion between the facing surface of the lens holder 12 facing the rising mirrors 1 and 2 and the facing surface of the focusing direction driving coil 13 facing the rising mirrors 1 and 2). A thick portion (reinforcing structure) that is thickened so as to have a shape corresponding to the cut-out surfaces 1a and 2a of the rising mirrors 1 and 2 is provided at a portion facing the cut-out surfaces 1a of the rising mirrors 1 and 2 ) 12a is formed. More specifically, when viewed from the direction in which the incident light enters the rising mirrors 1 and 2, a part of the lens holder 12 facing the rising mirrors 1 and 2, and the focus direction drive coil 13 is a cross-sectional shape formed by a part of the surface facing the rising mirrors 1 and 2 and a surface substantially parallel to the cut-out surfaces 1a and 2a of the rising mirrors 1 and 2 (in the configuration of FIG. 1B). A thick portion (reinforcing structure) 12a having a right triangle) is formed.

(Experimental example)
Next, the result of the natural vibration simulation performed for the drive unit 31 according to the present embodiment will be described.

  FIG. 6A to FIG. 6C show the dimensions of the drive unit 31 used in the simulation and the respective parts of the rising mirrors 1 and 2 used corresponding to the drive unit 31.

  As shown in FIG. 6C, the rising mirrors 1 and 2 have a length of 4 mm in the outgoing direction of the reflected light and a width in the direction perpendicular to the incident light and the outgoing light of 3.8 mm. Further, both end portions on the objective lens 3 and 4 side are notched at an angle of 45 ° with respect to the side surfaces of the rising mirrors 1 and 2, thereby perpendicular to incident light and outgoing light on the objective lens 3 and 4 side. The width in this direction is 1.8 mm.

  As shown in FIG. 6A, the lens holder 12 provided in the drive unit 31 has a rectangular shape of 4.5 mm × 8.0 mm. The width of the portion including the focus direction drive coil 13 and the radial direction drive coil 14 provided so as to sandwich the focus direction drive coil 13 from both sides is 3.0 mm.

  Moreover, as shown in FIG.6 (b), the width | variety between the relay boards 15 * 15 is 10 mm. Further, the length from the lowermost surface of the drive unit 31 (lowermost surface of the focus direction drive coil 13) to the uppermost surface (uppermost surface of the lens holder 12) is 3.3 mm, and the depth of the recess 12b in the drive unit 31 is increased. The thickness is 1.8 mm, and a thick portion 12a is provided at the corner of the recess 12b.

  This thick portion 12a has a cross-sectional shape at the bottom (a side formed by a part of the surface of the lens holder 12 that faces the rising mirrors 1 and 2, and the focusing direction driving coil 13 that faces the rising mirrors 1 and 2). The lens holder 12 is integrally formed so as to have a right isosceles triangular shape with a length of 1 mm of a part of the surface. In this simulation, the material of the lens holder 12 is polyphenylene sulfide (PPS) resin. The lens holder 12 has a Young's modulus of 30 GPa.

  FIG. 7A shows the result (simultaneous vibration mode) of the simulation for calculating the natural frequency using the finite element method for the drive unit 31 shown in FIGS. 6A to 6C. Shown in Further, as a comparative example, the same simulation was performed on a conventional drive unit having the same configuration as that shown in FIGS. 6A to 6C except that the thick portion 12a was not provided ( FIG. 7B shows the lowest natural vibration mode.

  As shown in FIG. 7A, the natural frequency of the drive unit according to this embodiment shown in FIGS. 6A to 6C was 26.5 kHz. On the other hand, as shown in FIG. 7B, the natural frequency of the conventional drive unit was 19.5 kHz. That is, the drive unit of the present embodiment was able to increase the natural frequency by about 35% compared to the conventional drive unit.

  As described above, the optical pickup device 100 according to the present embodiment includes the drive mirrors 1 and 2, the objective lenses 3 and 4, and the drive unit including the lens holder 12 that holds the objective lenses 3 and 4 movably. 31, and a part of the rising mirrors 1 and 2 is provided in a recess 12 b provided in the drive unit 31 with a predetermined distance from the drive unit 31. The rising mirrors 1 and 2 become narrower as they approach the objective lenses 3 and 4. In other words, the rising mirrors 1 and 2 have thin portions that become narrower as they approach the objective lenses 3 and 4.

  Thus, the distance between the lens holder 12 and the rising mirrors 1 and 2 is set to a predetermined value without increasing the thickness of the portion of the optical pickup device 100 where the lens holder 12 and the rising mirrors 1 and 2 are provided. Without narrowing the interval, the thick portion (reinforcing structure) 12a can be provided at the portion of the recess 12b facing the portion where the width of the rising mirrors 1 and 2 is narrowed. As a result, a drive unit having a high natural frequency (higher order resonance frequency) can be formed. As a result, a drive unit having a higher higher order resonance frequency can be realized.

  Therefore, it is possible to simultaneously realize the thinning of the optical pickup device 100 and the high rigidity of the drive unit 31. Thereby, for example, even when the thickness of the optical pickup device 100 is the same as that of the conventional one, the servo margin at the time of high-speed recording / reproducing can be increased, and stable servo control can be performed. Further, when the servo margin is configured so as to obtain the same servo margin as in the prior art, the thickness of the optical pickup device 100 around the rising mirrors 1 and 2 and the objective lenses 3 and 4 can be further reduced.

  In the present embodiment, the rising mirrors 1 and 2 have shapes in which the end portions on the objective lens 3 and 4 side are linearly cut out, but the present invention is not limited thereto, and the objective lenses 3 and 4 ( It is sufficient that the cross-sectional area of the cross section perpendicular to the optical axis of the reflected light becomes smaller as it gets closer to the lens holder 12 (as it goes in the direction in which the reflected light is emitted). For example, the cut surfaces 1a and 2a may be curved surfaces. The rising mirrors 1 and 2 are closer to the objective lenses 3 and 4 as the widths (outside dimensions) in the direction perpendicular to the optical axis of the incident light and the optical axis of the reflected light on the light incident surface of the light from the light source (reflective). It may be narrower toward the light exit direction.

  In the present embodiment, notched surfaces 1a and 2a are provided at both ends of the rising mirrors 1 and 2 on the objective lens 3 and 4 side. For this reason, since the shape of the drive unit 31 can be made symmetric, the center of gravity can be controlled easily, and the influence of unnecessary resonance caused by the deviation between the center of gravity and the power point can be reduced. However, as for the shape of the raising mirrors 1 and 2, for example, notched surfaces 1a and 2a may be provided at one end.

  Moreover, although this embodiment demonstrated the structure provided with 2 sets of a light source, an objective lens, and a raising mirror, it does not restrict to this. For example, a configuration including only one set of a light source, an objective lens, and a rising mirror may be used, or a configuration including three or more sets may be used. Alternatively, only one type of optical disk may be recorded or reproduced. For example, in order to enable recording / reproduction of a plurality of types of optical discs, when a plurality of sets of light sources, objective lenses, and rising mirrors are provided, the working distance of the objective lens differs depending on the type of the optical disc. It is necessary to ensure a wide movable range (clearance with the rising mirror) (for example, about ± 1 mm). On the other hand, according to the present embodiment, it is possible to reduce the thickness of the optical pickup device while ensuring a wide movable range of the drive unit. Therefore, the present invention is particularly suitable for an optical pickup device for recording / reproducing plural types of optical disks.

  In the present embodiment, the configuration has been described in which the rising mirror 1 has both the reflection and transmission functions. However, the present invention is not limited to this. For example, the upright mirror 1 has only a reflection function or a transmission function. Also good.

  Moreover, in this embodiment, although the thick part 12a is provided as a reinforcement structure in the corner part of the recessed part 12b in the drive unit 31, the structure of a reinforcement structure is not restricted to this. The reinforcing structure may be any structure that can increase the rigidity of the lens holder 12. For example, the reinforcing structure may be formed integrally with the lens holder 12. , May be attached by fitting or the like. The shape of the reinforcing structure is not particularly limited as long as the rigidity of the drive unit can be increased and it does not contact the rising mirrors 1 and 2 by servo drive.

  In the present embodiment, the drive unit 31 configured to support the two opposite sides of the lens holder 12 with the objective lenses 3 and 4 interposed therebetween has been described, but the configuration of the drive unit is not limited to this. For example, as shown in FIG. 8, a drive unit 31 'that supports the objective lens 3 in a cantilever structure may be used.

  Here, FIG. 8A is a cross-sectional view of the drive unit 31 ′ viewed from the incident light side, and FIG. 8B is a side view of the rising mirror 1 ′ disposed to face the drive unit 31 ′. FIG.

  As shown in FIG. 8A, the drive unit 31 ′ has a support member 16 attached to one end side (peripheral portion) of the lens holder 12 ′, and the lens holder 12 ′ provided with the objective lens 3. The end side (lens holding part) has a structure (saddle structure) that is thinner than the one end side.

  The rising mirror 1 ′ provided corresponding to the drive unit 31 ′ has only one of the end portions on the objective lens 3 side notched (notched surface 1 a ′). The portion of the lens holder 12 ′ that faces the cut-out surface 1 a ′ of the rising mirror 1 ′, that is, the base portion of the heel structure (the contact portion between the lens holding portion and the peripheral edge portion) is thicker than the heel portion. It is a thick part (reinforcing structure) 12a ′.

  In the configuration shown in FIGS. 8A and 8B as well as the drive unit 31, the optical pickup device 100 can be made thin and the drive unit 31 'can be highly rigid at the same time.

  Further, when the drive unit 31 ′ shown in FIGS. 8A and 8B is used, the reinforcing structure 12a ′ can be added to the drive unit 31 ′ only by chamfering one vertex of the rising mirror 1 ′. Can be formed. For this reason, the number of cuts of the rising mirror 1 'can be reduced, the manufacturing process (chamfering process) can be simplified, and the manufacturing cost of the rising mirror can be reduced.

  The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the claims. That is, embodiments obtained by combining technical means appropriately modified within the scope of the claims are also included in the technical scope of the present invention.

FIG. 2A is a perspective view of an objective lens driving device and a rising mirror according to an embodiment of the present invention. (B) is the side view which looked at the objective lens drive device and raising mirror which concern on one Embodiment of this invention from the direction which the light from a light source injects with respect to this raising mirror. (A) It is sectional drawing which shows the structure of the optical pick-up apparatus concerning one Embodiment of this invention, (b) is the top view which looked at the optical pick-up apparatus from the direction side which the light reflected by the standing mirror radiate | emits. is there. It is a perspective view which shows the objective lens drive device which concerns on one Embodiment of this invention. (A) is the side view which looked at the standing-up mirror which concerns on one Embodiment of this invention from the direction perpendicular | vertical to the incident light and emitted light with respect to this standing-up mirror. (B) is the side view which looked at the standing-up mirror which concerns on one Embodiment of this invention from the direction in which the light from a light source injects with respect to this standing-up mirror. It is a perspective view which shows the structure of the raising mirror which concerns on one Embodiment of this invention. (A) is a top view of the objective lens drive device concerning one Embodiment of this invention used for the natural vibration simulation. (B) is sectional drawing of the objective-lens drive device shown to (a). (C) is a top view of the raising mirror arrange | positioned facing the objective-lens drive device of (a), (b). (A) is explanatory drawing which shows the result of the natural vibration simulation with respect to the drive unit concerning this embodiment, (b) is explanatory drawing which shows the result of the natural vibration simulation with respect to the conventional drive unit. (A) is sectional drawing of the modification of the drive unit concerning one Embodiment of this invention. (B) is the arrow view which looked at the drive unit shown to (a) from the A direction. It is a perspective view which shows the structure of the conventional raising mirror. (A) is sectional drawing of the conventional objective lens drive device and a raising mirror. (B) is the side view which looked at the conventional objective-lens drive device and a raising mirror from the direction in which the light from a light source injects with respect to this raising mirror.

Explanation of symbols

1,2,1 'Rising mirror (optical element)
1a, 2a, 1a 'notch (cross-section reduced portion)
1b entrance surface 1c exit surface 2b entrance surface 3, 4 objective lens 12, 12 ′ lens holder (lens holding portion)
12a, 12a 'Thick part (reinforced structure)
12b Concave part 13 Focus direction drive coil (peripheral part)
14 Radial direction drive coil (peripheral part)
15 Relay board (periphery)
16 Support member 17 Magnet 18 Base plate 19 FPC
20 Dump block 30 Objective lens driving device 31, 31 'Driving unit (objective lens holding device)
32 Fixed unit 100 Optical pickup device 101a Light source (first light source)
101b Light source (second light source)

Claims (21)

A light source, an objective lens, an optical element that is provided at a predetermined interval with respect to the objective lens, reflects incident light from the light source, and causes reflected light to enter the objective lens; and In an optical pickup provided with a drive unit that is movably held relative to an optical element,
At least a part of the optical element facing the drive unit is provided with a cross-sectionally reduced portion in which the area of the cross section perpendicular to the reflected light becomes smaller as it approaches the drive unit,
An optical pickup device, wherein a reinforcing structure for increasing the rigidity of the drive unit is provided at a position facing the reduced section of the drive unit. The drive unit is
A lens holding unit that holds the objective lens, and a peripheral portion that is provided at a position farther from the optical axis of the incident light than the lens holding unit, and holds the lens holding unit,
The thickness in the first direction parallel to the optical axis of the incident light to the objective lens in the lens holding portion is thinner than the thickness in the first direction at the peripheral edge,
The optical element is disposed to face the lens holding portion and the peripheral portion,
The optical pickup device according to claim 1, wherein the reinforcing structure is provided at a contact portion between the lens holding portion and the peripheral portion. The reinforcing structure is
The optical pickup device according to claim 2, wherein the optical pickup device has a cross-sectional shape that abuts against a surface facing the optical element in the lens holding portion and a surface facing the optical element in the peripheral edge.   The optical pickup device according to claim 1, wherein the reinforcing structure is formed integrally with at least a part of the drive unit.   The optical element includes an incident surface inclined by approximately 45 degrees with respect to the optical axis of the incident light. The optical axis direction of the incident light incident on the incident surface is converted by approximately 90 degrees to the objective lens. The optical pickup device according to claim 1, wherein the optical pickup device is incident.   2. The optical pickup device according to claim 1, wherein the cross-sectional reduction portion is provided at an end portion of the optical element on an emission direction side of the reflected light.   The cross-sectional reduction part is characterized in that, when viewed from a direction in which the incident light is incident, a width in a direction perpendicular to the reflected light becomes narrower toward an emission direction of the reflected light. Item 7. The optical pickup device according to Item 6.   The optical pickup device according to claim 6, wherein an outer shape of the optical element viewed from a direction in which the incident light enters is a shape obtained by chamfering at least a part of a rectangular shape.   2. The optical element according to claim 1, wherein an outer shape of the optical element viewed from a direction in which the incident light enters is axially symmetric with respect to an axis parallel to the optical axis of the reflected light. Optical pickup.   2. The optical pickup device according to claim 1, wherein an outer shape of a light beam of the incident light falls within an incident surface of the incident light in the optical element.   A second light source that emits light having a wavelength different from that of the light source; a second objective lens; and a second optical element that reflects the light emitted from the second light source and causes reflected light to enter the second objective lens. 2. The optical pickup device according to claim 1, wherein the optical element transmits incident light from the second light source and enters the second optical element.   The optical pickup device according to claim 11, wherein an outer shape of a light beam transmitted through the optical element is within an emission surface of the transmitted light in the optical element.   The optical pickup device according to claim 11, wherein an outer shape of a light beam of incident light that is transmitted through the optical element and incident on the second optical element is within an incident surface of the second optical element.   At least a part of the second optical element facing the drive unit is provided with a cross-sectional reduction portion in which an area of a cross section perpendicular to the reflected light becomes smaller toward the drive unit. The optical pickup device according to claim 11. An optical element that is provided in an optical pickup device, reflects incident light from a light source, and makes reflected light enter an objective lens,
An optical element comprising a cross-sectional reduction portion in which an area of a cross section perpendicular to the reflected light becomes smaller toward an end of the reflected light in an emission direction side toward the emission direction of the reflected light .   The optical element according to claim 15, wherein an outer shape viewed from a direction in which the incident light enters is a shape obtained by chamfering at least a part of a rectangular shape.   The optical element according to claim 15, wherein an outer shape viewed from a direction in which the incident light enters is axially symmetric with respect to an axis parallel to the optical axis of the reflected light.   The optical element according to claim 15, wherein the optical element reflects light in the first wavelength range and transmits light in the second wavelength range. The optical pickup device includes a light source, an objective lens, and an optical element that reflects incident light from the light source and causes reflected light to enter the objective lens. An objective lens holding device that holds the optical element movably relative to the optical element in a state of being spaced apart from each other,
A lens holding unit that holds the objective lens, and a peripheral portion that is provided at a position farther from the optical axis of the incident light than the lens holding unit, and holds the lens holding unit,
The thickness in the first direction parallel to the optical axis of the incident light to the objective lens in the lens holding portion is thinner than the thickness in the first direction at the peripheral edge,
An objective lens holding device, wherein a reinforcing structure is provided at a contact portion between the lens holding portion and the peripheral edge portion. The reinforcing structure is
21. The optical pickup apparatus according to claim 20, wherein the optical pickup device has a cross-sectional shape in contact with a surface facing the optical element in the lens holding portion and a surface facing the optical element in the peripheral portion.   21. The optical pickup device according to claim 20, wherein the reinforcing structure is formed integrally with at least one of the lens holding portion and the peripheral portion.

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