JP2011233194A - Lens unit and lens for pickup device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lens unit and a lens for a pickup device capable of positioning a lens with respect to a holder by a simple equipment which does not apply large load.SOLUTION: The lens unit for a pickup device includes; a lens having a lens portion with a first lens surface and a second lens surface formed on the both sides of the lens portion and a substantially-disc flange portion which protrudes in a flange shape from an edge of the lens portion, with multiple concavities formed on the whole circumference of the edge of the flange part, at equal intervals in a circumferential direction and exhaustively in a thickness direction; and a holder which is a plate-like member with a through-hole formed in it. The inner peripheral surface of the through-hole is a slope of a size which makes it possible to face to the flange part of the lens.

Description

  The present invention relates to a lens unit and a lens used in a pickup device for reading information recorded on an optical disc.

  An optical disk device is used to read or write information recorded on the optical disk. The optical disc apparatus has a spindle for rotating the optical disc and a pickup device for reading or writing information recorded on the optical disc by irradiating the rotating disc with laser light.

  The pickup device has a laser light source, a photo sensor, and a lens unit. The lens unit has a lens fixed to a holder. As a lens unit of a conventional pickup device, there is one described in Patent Document 1.

  The lens of the conventional lens unit described in Patent Document 1 has a shape in which a disk-shaped flange portion protrudes from the outer edge of a lens portion having lens surfaces formed on both front and back surfaces. On the other hand, the holder has a through hole for placing the lens portion of the lens on the holder and allowing the laser beam to pass through the lens portion, and an inclined surface on the outer edge of the through hole on which the flange portion of the lens is placed. .

  The inclined surface of the holder is a conical surface whose diameter increases as it approaches the optical disk. Since it is an inclined surface on which the flange portion of the lens is mounted, the lens can be inclined to some extent with respect to the holder while maintaining the state where the flange portion is mounted on the inclined surface. When fixing the lens to the holder, position the lens while moving the lens on the holder so that the optical axis of the lens is substantially parallel to the rotation axis of the spindle of the optical disk device, and then fix the lens to the holder. It has become.

JP 2007-193856 A

  As described above, in the conventional configuration, since the flange portion has a disk shape, the outer edge of the flange portion contacts the inclined surface of the holder over the entire circumference. For this reason, the frictional force acting between the lens and the holder becomes large, and it is necessary to apply a large load to the lens in order to move the lens on the holder. In addition, in the conventional configuration, when the lens is inclined with respect to the inclined surface, the contact area between the inclined surface and the lens is rapidly decreased, and the frictional force between the lens and the inclined surface is rapidly decreased. At this time, since a large load that can move the lens against the frictional force is applied to the lens, if the frictional force decreases rapidly, the balance between the load applied to the lens and the frictional force is lost, and the lens moves rapidly. However, there is a possibility that the desired position is greatly deviated. As described above, in the conventional configuration, in order to accurately position the lens, a large load can be applied to the lens, and the load applied to the lens can be controlled with high responsiveness so that the lens does not move suddenly. Needed high performance equipment.

  The present invention has been made to solve the above problems. That is, an object of the present invention is to provide a lens unit and a lens for a pickup device that enable positioning of the lens with respect to the holder with a simple device that does not apply a large load to the lens.

  In order to achieve the above object, a lens unit for a pickup device according to the present invention includes a lens having a lens portion having a first lens surface and a second lens surface formed on the front and back, and a flange shape from the edge of the lens portion. And a plurality of recesses are formed in the entire circumference of the outer periphery of the flange portion at equal intervals in the circumferential direction and in the entire thickness direction. The holder has a through-hole. The inner peripheral surface of the through hole is an inclined surface having a dimension capable of coming into contact with the flange portion of the lens.

  In the present invention, since the concave portion is formed in the flange portion of the lens as described above, the contact area between the lens and the inclined surface is small, and the frictional force acting between the lens and the inclined surface is small. Therefore, the load applied to the lens to move the lens on the holder is small. Also, since the frictional force that originally acts between the lens and the inclined surface is small, even if the lens tilts on the inclined surface, the frictional force does not decrease significantly, and the lens moves unexpectedly and suddenly. There is no. As described above, the lens unit of the present invention does not need to apply a large load to the lens, and does not need to apply a load to the lens with high responsiveness, so that the lens can be positioned with respect to the holder with a simple device. . Moreover, a lens can be reduced in weight by forming a recessed part in a flange part.

  The inclined surface is preferably formed so that the diameter of the through hole increases from the light source side of the pickup device toward the optical disk side read or written by the pickup device.

  In this case, it is more preferable that the holder is formed such that the outer edge portion of the through hole on the optical disc side of the holder is closer to the optical disc than the lens attached to the holder.

  With such a configuration, even when the optical disk is tilted and approaches the pickup device, the optical disk comes into contact with the outer edge of the holder, and the optical disk does not contact the lens. Thus, according to the above configuration, damage to the lens due to contact between the optical disk and the lens is prevented.

  Here, the inclined surface may be a conical surface centered on an axis substantially parallel to the rotation axis of the optical disc read or written by the pickup device. In this case, it is preferable that the angle of the inclined surface with respect to the thickness direction of the holder is 40 to 50 °.

  Alternatively, the inclined surface is a spherical surface having an axis substantially parallel to the rotation axis of the optical disk read or written by the pickup device.

  In order to achieve the above object, the lens for the pickup device of the present invention protrudes in a flange shape from the lens portion having the first lens surface and the second lens surface formed on the front and back surfaces and the edge portion of the lens portion. A substantially disk-shaped flange portion, and a plurality of recesses are formed in the entire circumference of the outer periphery of the flange portion at equal intervals in the circumferential direction and in the entire thickness direction, and formed between adjacent recesses. The length of the projected portion along the circumferential direction of the flange is 0.8 times or less the length of the plurality of recessed portions along the circumferential direction of the flange.

  Alternatively, the lens for the pickup device according to the present invention includes a lens portion having a first lens surface and a second lens surface formed on the front and back sides, and a substantially disk-shaped flange portion protruding in a flange shape from an edge portion of the lens portion. A plurality of recesses in the thickness direction are formed at equal intervals in the circumferential direction on the entire circumference of the outer edge of the flange portion, and the depth of the recess is generated by the light source of the pickup device. The size is such that it does not intersect with the light beam incident on the lens unit. Preferably, the depth of the concave portion is set such that the concave portion does not reach the lens portion.

  As described above, according to the present invention, a lens unit and a lens for a pickup device that enable positioning of the lens with respect to the holder with a simple device are realized.

FIG. 1A and FIG. 1B are a perspective view and a cross-sectional view, respectively, of the optical disk device according to the first embodiment of the present invention. FIG. 2 is a top view of the optical disc apparatus according to the first embodiment of this invention. FIG. 3 is a top view of the lens according to the first embodiment of the present invention viewed from the optical disk side. FIG. 4 is a cross-sectional view of the lens unit and the optical disc according to the first embodiment of the present invention. FIG. 5 is a block diagram of the lens fixing device according to the first embodiment of the present invention. FIG. 6 is a cross-sectional view of a lens unit and an optical disc according to the second embodiment of the present invention.

  Embodiments of the present invention will be described below. FIG. 1A is a perspective view of an optical disc apparatus according to the first embodiment of the present invention. FIG. 1B is a cross-sectional view of the optical disc apparatus of the present embodiment. The optical disc apparatus 100 of this embodiment is an apparatus for reading information recorded on the optical disc 200. FIG. 2 is a top view of the optical disc apparatus of the present embodiment.

  The optical disc apparatus 100 has a pickup device 130. The pickup device 130 has a movable unit 131 to which the lens unit 150 is fixed. As shown in FIG. 1A, the movable unit 131 is guided by a pair of guide shafts 133 </ b> L and 133 </ b> R, so that the moving direction is limited to the radial direction of the optical disc 200. Further, the movable unit 131 is slid in the radial direction of the optical disc 200 by a driving means (not shown). In FIG. 1A, the pickup device 130 and the lens unit 150 are actually located behind the optical disc 200. However, in order to make the shapes of the pickup device 130 and the lens unit 150 clearer, These are indicated by solid lines.

  As shown in FIGS. 1B and 2, the movable unit 131 emits a laser beam for reading or writing information recorded on the optical disc 200 to the optical disc 200 via the lens unit 150, and also for the optical disc. An optical unit 110 for detecting the laser beam reflected by 200 is incorporated. The optical unit 110 includes a laser diode 111, a beam splitter 112, a collimator lens 113, an information detection lens 114, a photo sensor 115, a rising mirror 116, a liquid crystal aberration correction element 117, and a quarter wavelength plate 118. In addition, the lens unit 150 is obtained by bonding and fixing a lens 151 to a holder 152.

  Laser light emitted from the laser diode 111 enters the liquid crystal aberration correction element 117 via the beam splitter 112 and the collimator lens 113. The phase of the laser light is changed by the liquid crystal aberration correction element 117 and is incident on the rising mirror 116 via the quarter wavelength plate 118. Then, the light is deflected by the reflecting surface 116 a (FIG. 1B) of the rising mirror 116 and enters the lens 151, and the focal point is formed on the optical disc 200 by the action of the lens 151. Next, the return light is reflected by the half mirror 112 a (FIG. 2) of the beam splitter 112 and received by the photo sensor 115 via the information detection lens 114. The laser beam received by the photo sensor 115 is used as an information signal of the optical disc 200 as described above.

  The shape of the lens 151 will be described below. FIG. 3 is a top view of the lens 151 as viewed from the optical disc 200 side (FIG. 1B). FIG. 4 is a cross-sectional view of the lens unit 150 and the optical disc 200.

As shown in FIG. 4, the lens 151 has a first lens surface 151a1 on one surface (optical disc 200 side) and a second surface on the other surface (rising mirror 116 (FIG. 1 (b)) side). The lens portion 151a has a lens surface 151a2 and a substantially disk-shaped flange portion 151b protruding from the outer edge of the lens portion 151a in a flange shape. As shown in FIG. 3, the flange portion 151b has a plurality of concave portions 151b1 formed on the outer peripheral surface thereof at substantially equal intervals in the circumferential direction, and the upper surface of the lens 151 has a star shape as a whole. . Incidentally, as shown in FIG. 3, the recess 151b1 is formed over a (toward the direction to the optical axis ax _l of the lens 151) throughout the thickness direction of the flange portion 151b.

The surface of the first lens surface 151a1 side of the flange portion 151b has a flange reflecting plane portion 151b3 is a plane perpendicular to the optical axis ax _l of the lens 151.

The holder 152 is a plate-like member having a through-hole 152a formed in a direction (vertical direction in FIG. 4) from the rising mirror 116 (FIG. 1B) toward the optical disc 200. The portion of the through-hole 152a on the optical disc 200 side is an inclined surface (conical base surface) 152a1 that increases in diameter as it approaches the optical disc 200. The diameter of the narrowest part of the inclined surface 152a1 (that is, the diameter of the part that is located closest to the rising mirror 116) is dh ₁ , and the diameter of the thickest part of the inclined surface 152a1 (that is, closest to the optical disc 200). When the diameter of the portion is dh ₂ and the outer diameter of the lens 151 is dl, dh ₂ >dl> dh ₁ is satisfied. For this reason, when the lens 151 is attached to the holder 152, the flange 151b is put on the inclined surface 152a1. The lens 151 is bonded and fixed to the holder 152 by injecting the adhesive ad into the gap SP between the outer peripheral surface of the flange portion 151b and the through hole 152a in a state where the flange portion 151b is on the inclined surface 152a1. The

In order for the information recorded on the optical disk 200 to be correctly read or written by the pickup device 130, the spindle 140 (FIG. 1A, FIG. It is necessary to perform positioning so that the rotation axis ax _{s of} 2) and the optical axis ax _l of the lens 151 are parallel to each other. In this embodiment, the movable unit 131 is strictly positioned with respect to the spindle 140 and the holder 152 is strictly positioned with respect to the movable unit 131. However, as described above, the lens 151 is simply placed on the holder 152. Therefore, it is necessary to strictly position the lens 151 with respect to the holder 152 when the lens 151 is bonded. That is, the lens fixing device for fixing the lens 151 to the holder 152 needs to adhere the lens 151 after the lens 151 is strictly positioned with respect to the holder 152.

  The lens fixing device of this embodiment will be described below. FIG. 5 is a block diagram showing an outline of a lens fixing device for fixing the lens 151 to the holder 152.

  As shown in FIG. 5, the lens fixing device 300 includes a holder holding unit 310 that holds the holder 152, a detection unit 320 that detects the inclination of the optical axis of the lens 151 with respect to the holder 152, and the lens 151 on the holder 152. An adhesive is supplied to a gap between the lens holding jig 331 that biases toward the holder 152, a moving unit 332 that moves the lens 151 through the lens holding jig 331 to be inclined, and the holder 152 and the lens 151. An adhesive unit 340 that fixes the lens 151 to the holder 152, a detection unit 320, a moving unit 332, and an operation computer system 350 for operating the adhesive unit 340 are provided.

  The detection unit 320 includes a light source unit 321 that generates parallel light, a half mirror 322, an imaging lens 323, and an imaging camera 324.

The parallel light generated from the light source unit 321 enters the half mirror 322. The parallel light until it enters the half mirror 322 is defined as the first light P1. The half mirror 322 bends the incident first light P <b> 1 by 90 ° in the direction toward the lens 151. Light that is bent by the half mirror 322 and travels toward the lens 151 is defined as second light P11. Incidentally, the traveling direction D of the second light P11 has an optical axis ax _l of the lens 151 when the lens 151 has been properly attached to the holder 152 (i.e., the direction of the optical axis ax _s of the spindle 140 of the optical disc apparatus 100) Parallel.

The second light P11 is reflected by the edge reflection flat portion 151b3 (FIG. 3) of the lens 151. The light reflected by the lens 151 is defined as the third light P21. The third light P21 passes through the half mirror 322. The light after passing through the half mirror 322 is defined as the fourth light P2. The fourth light P <b> 2 is collected by the imaging lens 323 and enters the imaging camera 324. Here, the imaging lens 323, so that the optical axis ax parallel light parallel to _i are condensed on the imaging surface of the imaging camera 324 is positioned relative to the imaging camera 324.

  The operation computer system 350 includes a computer main body 351, a monitor 352, and an operation unit 353 such as a keyboard and a mouse. The image output terminal of the imaging camera 324 is connected to the computer main body 351 of the operation computer system 350.

  The computer main body 351 processes the video signal transmitted from the imaging camera 324 and displays an image captured by the imaging camera 324 on the screen 352 a of the monitor 352. The light reflected by the edge reflection flat portion 151b3 of the lens 151 is displayed as a light spot S11 on the dark field on the screen 352a. Further, the computer main body 351 displays an inclination detection mark M on the screen 352a. The inclination of the optical axis of the lens 151 appears as a positional deviation between the mark M and the light spot S11.

  Further, the computer main body 351 can control the moving unit 332, and the lens 151 can be operated by the moving unit 332 via the lens holding jig 331 so that the light spot S 11 overlaps the mark M by operating the operating unit 353. Can be adjusted so that the optical axis of the lens 151 is in the correct position.

  In the present embodiment, as shown in FIGS. 3 and 4, the outer shape of the flange portion 151 b of the lens 151 is a star shape. Therefore, in a state where the lens 151 is placed on the holder 152, only the boundary portion 151b2 (FIG. 3) of the lens 151 comes into contact with the inclined surface 152a1 of the holder 152, and the contact area between the lens 151 and the inclined surface 152a1 is small. It will be a thing. When the lens 151 is bonded and fixed to the holder 152, the lens 151 needs to be urged toward the inclined surface 152a1 by the lens holding jig 331 (FIG. 5) so that the lens 151 does not float from the holder 152. In the conventional configuration in which the concave portion 151b1 is not formed in the flange portion 151b of the lens 151 (that is, the flange portion 151b is circular), the frictional force between the lens 151 and the holder 152 becomes extremely large, and the lens In order to move 151 on the holder 152, the moving unit 332 (FIG. 5) of the lens fixing device 300 needs to apply a large load to the lens 151. In addition, in the conventional configuration, when the lens 151 is inclined with respect to the inclined surface 152a1, the contact area between the inclined surface 152a1 and the lens 151 is rapidly reduced, and the frictional force between the lens 151 and the inclined surface 152a1 is rapidly increased. To decrease. At this time, since the moving unit 332 applies a large load to the lens 151 enough to move the lens 151 against the frictional force, the load and the frictional force applied to the lens 151 by the moving unit 332 when the frictional force rapidly decreases. There is a possibility that the balance of the lens will be lost and the lens 151 will suddenly deviate greatly from the desired position.

  In contrast to the above-described conventional configuration, in the configuration of the present embodiment, the frictional force acting between the lens 151 and the inclined surface 152a1 is small. Therefore, the lens fixing device 300 is used to move the lens 151 on the holder 152. The magnitude of the load applied to the lens 151 by the moving unit 332 becomes small. Further, since the frictional force originally acting between the lens 151 and the inclined surface 152a1 is small, even if the lens 151 is inclined on the inclined surface 152a1, the frictional force is not greatly reduced, and the lens 151 is not intended. There is no sudden movement.

  The inclination angle of the inclined surface 152a1 with respect to the thickness direction of the holder 152 (the vertical direction in FIG. 4) is 40 to 50 °, and preferably about 45 °. However, the inclination angle of the inclined surface 152a1 is not limited to this range, and may be in the range of about 30 to 70 ° depending on the lens shape. When the angle of the inclined surface 152a1 is shallow (that is, close to a plane perpendicular to the thickness direction of the holder 152), the size of the holder 152 becomes large, and the holder 152 and the second lens surface 151a2 may interfere with each other. There is sex. On the other hand, when the angle of the inclined surface 152a1 is deep (that is, close to a plane parallel to the thickness direction of the holder 152), the frictional resistance between the inclined surface 152a1 and the lens 151 becomes large. Therefore, in the present embodiment, the angle of the inclined surface 152a1 is about 45 °, the size of the holder 152 is small, the holder 152 and the second lens surface 151a2 do not interfere, and the inclined surface 152a1 and the lens 151 The frictional resistance is small.

  In order to minimize the frictional force acting between the lens 151 and the inclined surface 152a1, the size of the boundary 151b2 (FIG. 3) is preferably as small as possible. Specifically, it is most preferable that the length lb of the boundary portion 152b2 is not more than 0.2 times the length la of the concave portion 151b1. However, even if the length lb is not more than 0.8 times the length la of the recess 151b1, the magnitude of the load applied to the lens 151 by the moving unit 332 of the lens fixing device 300 can be sufficiently reduced.

As shown in FIG. 4, in the present embodiment, a protrusion 152 b that protrudes in a cylindrical shape toward the optical disc 200 is formed on the outer side in the radial direction of the inclined surface 152 a 1 of the holder 152. The protrusion 152 b has a height such that the tip thereof is positioned slightly closer to the optical disc 200 than the lens 151 attached to the holder 152. There is a possibility that the optical disc 200 may be tilted with respect to the rotation axis ax _s of the spindle 140 due to an attachment error to the spindle 140 (FIG. 1B) or the eccentricity of the disc itself. Therefore, the pickup device 130 requires means for protecting the lens 151 from the optical disk 200 rotating at high speed. The pickup device having a conventional configuration protects the lens by a cover attached to the flange portion of the lens. Such a cover attached to the lens requires a certain degree of strength so that it can withstand an impact at the time of collision, and thus a cover having a sufficient thickness is required. In recent years, the focal length of the lens has become shorter as the lens becomes smaller and smaller in diameter. When the cover is attached to the lens, the distance between the optical disk and the cover becomes very close, and the cover and the disk come into contact with each other. There is a possibility that the probability increases and the reading or writing of the optical disc becomes unstable. In particular, a lens for reading information from a high-density optical disk such as a Blu-ray (trademark) optical disk tends to have a short focal length because NA is large and an effective diameter cannot be increased. In the configuration in which the cover is attached to a simple lens, the probability that the cover and the disk are in contact with each other is further increased. On the other hand, in this embodiment, the protrusion 152b of the holder 152 functions as a protection unit for protecting the lens 151 from the optical disc 200. Since the protrusion 152b is not attached to the surface of the flange 151b of the lens 151 on the optical disc 200 side, the position of the tip can be set slightly closer to the optical disc 200 than the lens 151. For this reason, in the configuration of the present embodiment, the probability that the protrusion 152b and the optical disc 200 are in contact with each other is kept relatively small. As described above, according to the configuration of the present embodiment, the lens 151 can be protected from the optical disc 200 without making the reading of the optical disc unstable.

In the present embodiment, the depth of the concave portion 151b1 of the lens 151 (that is, the maximum distance between the circumscribed circle C _O (FIG. 3) of the lens 151 and the concave portion 151b) rp is incident on the light beam incident on the lens 151. The lens 151 can be made lighter as much as possible by deepening it to the extent that it does not reach the range. In the present embodiment, as shown in FIG. 4, a diaphragm 152 a 2 having a diameter da is formed on the rising mirror 116 side of the through hole 152 a of the holder 152. Therefore, a preferable range of rp is expressed by the following formula 1 using the outer diameter dl of the lens 151 and the diameter da of the diaphragm 152a2.

However, since the optical performance of the lens 151 is affected when the concave portion 151b1 reaches the lens portion 151a, it is more desirable that the depth rp of the concave portion 151b1 is not large enough to reach the lens portion 151a. That is, a preferable range of rp is expressed by the following formula 2 using the outer diameter dl of the lens 151 and the diameter dl ₀ (FIG. 4) of the lens portion 151a.

For example, if the size of the diameter dl ₀ of the lens portion 151 a is exactly halfway between the outer diameter dl of the lens 151 and the diameter da of the diaphragm 152 a 2 (that is, dl ₀ = (dl + da) / 2), the preferable range of rp is The following equation 3 is shown.

  In the first embodiment of the present invention described above, as shown in FIG. 4, in the holder 152, the inclined surface 152a1 on which the lens 151 is placed is a conical surface. However, the present invention is not limited to the above-described configuration, and the inclined surface 152a1 has another diameter that increases as it approaches the optical disc 200, as in the second embodiment of the present invention described below. It may be a curved surface.

  FIG. 6 shows a cross-sectional view of the lens unit 150 and the optical disc 200 according to the second embodiment of the present invention. In this embodiment, instead of the holder 152 of the first embodiment, a holder 153 having a different shape of the inclined surface 153a1 is used. Since the other configuration of the present embodiment is the same as that of the first embodiment, description thereof is omitted.

  In the present embodiment, as shown in FIG. 6, the inclined surface 153a1 is formed in a spherical shape. That is, the inclination of the inclined surface 153a1 gradually becomes steeper toward the outer side of the lens 151 in the radial direction. Therefore, compared to the first embodiment in which the inclined surface 152a1 is a conical surface, the angle at which the lens 151 can be inclined can be increased without increasing the lens radial dimension of the holder.

  Further, when the diameter of the inclined surface 153a1 is set to be substantially equal to the outer diameter dl (FIG. 3) of the lens 151, all of the boundary portion 151b2 (FIG. 3) of the flange portion 151b of the lens 151 is inclined even when the lens 151 is inclined. The state of being in contact with the inclined surface 153a1 is reliably maintained, and the lens 151 is more stably held on the holder 153.

  The lens 151 according to the first and second embodiments of the present invention described above is a star-shaped lens in which the concave portion 151b1 formed in the flange portion 151b has a curved surface shape. However, the present invention is not limited to the above configuration, and the shape of the lens 151 may be a polygonal shape in which the concave portion 151b1 is planar. However, the configuration in which the concave portion 151b1 is a curved surface is more preferable because the lens 151 can be further reduced in weight.

  The above-described pickup devices according to the first and second embodiments of the present invention are for reading or writing information recorded on a CD, or an optical disk of CD and DVD format. However, the present invention is not limited to the above-described configuration, and pickup apparatuses for reading or writing information recorded on CD, DVD, and Blu-ray (trademark) type optical discs are also included in the present invention. . That is, instead of the lens 151 of the present embodiment, a configuration in which the movable unit 131 is provided with a three-wavelength compatible objective lens capable of reading a CD, DVD, and Blu-ray type optical disc. Alternatively, the pickup device corresponding to the optical disk of CD and DVD format and the optical disc of Blu-ray format may include a lens and an optical unit 110 (FIGS. 1, 2, and 4) for the optical disc of CD and DVD format, and Blu- A lens for a ray type optical disk and an optical unit 110 are provided in the movable unit 131. That is, a lens for a CD and DVD type optical disc having a relatively long focal length and a lens for a Blu-ray type optical disc having a short focal length are arranged side by side on the movable unit 131.

  It should be noted that a CD and DVD type optical disk lens and a Blu-ray type optical disk lens may be attached to a common holder. In other words, the holder is separately provided with a through hole for a lens for a CD and DVD type optical disc and a through hole for a lens for a Blu-ray type optical disc. And all these through-holes become an inclined surface like the 1st or 2nd embodiment.

  In general, the focal length of a lens for reading information from an optical disk or recording information on an optical disk is smaller for an optical disk having a higher recording density. For this reason, the inclination allowed for the lens when attached to the holder becomes smaller as the lens for an optical disc having a higher recording density. In the configuration of the present embodiment, the load applied to the lens for tilt adjustment can be controlled with high responsiveness. Therefore, even when a lens with a small focal length as described above is attached to the holder, ( It is possible to position the lens in the holder (within the tolerance of the lens).

DESCRIPTION OF SYMBOLS 100 Optical disk apparatus 130 Pickup apparatus 150 Lens unit 151 Lens 151b Flange part 151b1 Recessed part 152 Holder 152a Through-hole 152a1 Inclined surface 153 Holder 153a1 Inclined surface 200 Optical disk

Claims (9)

A lens unit for a pickup device having a lens and a holder for holding the lens,
The lens is
A lens part having a first lens surface and a second lens surface formed on the front and back;
A substantially disk-shaped flange portion protruding in a flange shape from an edge portion of the lens portion;
And a plurality of concave portions are formed in the entire circumference of the outer edge of the flange portion at equal intervals in the circumferential direction and in the entire area in the thickness direction,
The holder is a plate-like member in which a through hole is formed, and an inner peripheral surface of the through hole is an inclined surface having a dimension capable of coming into contact with a flange portion of the lens. Lens unit for equipment.   The inclined surface is formed so that the diameter of the through hole increases from the light source side of the pickup device toward the optical disk side read or written by the pickup device. A lens unit for the pickup apparatus described.   3. The pickup device according to claim 2, wherein the holder is formed so that an outer edge portion of the through hole on the optical disc side is closer to the optical disc than a lens attached to the holder. Lens unit.   The lens for a pickup device according to claim 2 or 3, wherein the inclined surface is a truncated cone surface centering on an axis parallel to a rotation axis of an optical disk read or written by the pickup device. unit.   The lens unit of the pickup device according to claim 4, wherein an angle of the inclined surface with respect to a thickness direction of the holder is 40 to 50 °.   4. The lens unit for a pickup device according to claim 2, wherein the inclined surface is a spherical surface centered on an axis parallel to a rotation axis of an optical disk read or written by the pickup device. . A lens for a pickup device,
A lens part having a first lens surface and a second lens surface formed on the front and back;
A substantially disk-shaped flange portion protruding in a flange shape from an edge portion of the lens portion;
Have
A plurality of recesses are formed in the entire circumference of the outer edge of the flange portion at equal intervals in the circumferential direction and in the entire area in the thickness direction,
The length of the convex portion formed between adjacent concave portions along the circumferential direction of the flange is the length of the plurality of concave portions along the circumferential direction of the flange. A lens for a pickup device, characterized by being 0.8 times or less. A lens for a pickup device,
A lens part having a first lens surface and a second lens surface formed on the front and back;
A substantially disk-shaped flange portion protruding in a flange shape from an edge portion of the lens portion;
Have
A plurality of recesses are formed in the entire circumference of the outer edge of the flange portion at equal intervals in the circumferential direction and in the entire area in the thickness direction,
The lens for a pickup device, wherein the depth of the recess is such that the recess does not intersect with a light beam generated by a light source of the pickup device and incident on the lens unit. 9. The lens for a pickup device according to claim 8, wherein the depth of the concave portion is such a size that the concave portion does not reach the lens portion.

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