JP2005276355A - Optical pickup - Google Patents

Optical pickup Download PDF

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Publication number
JP2005276355A
JP2005276355A JP2004089987A JP2004089987A JP2005276355A JP 2005276355 A JP2005276355 A JP 2005276355A JP 2004089987 A JP2004089987 A JP 2004089987A JP 2004089987 A JP2004089987 A JP 2004089987A JP 2005276355 A JP2005276355 A JP 2005276355A
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Japan
Prior art keywords
lens
holder
optical pickup
grease
sliding support
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Pending
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JP2004089987A
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Japanese (ja)
Inventor
Hiroshi Ezawa
寛 江澤
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Olympus Corp
オリンパス株式会社
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Application filed by Olympus Corp, オリンパス株式会社 filed Critical Olympus Corp
Priority to JP2004089987A priority Critical patent/JP2005276355A/en
Publication of JP2005276355A publication Critical patent/JP2005276355A/en
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Abstract

A high-performance optical pickup capable of smoothly moving a lens for correcting spherical aberration and capable of precisely controlling the position is provided.
A light source 101, an objective lens 107 for condensing a light beam emitted from the light source 101 on a recording surface 108a of an optical recording medium 108, and an optical path between the light source 101 and the objective lens 107 are disposed. In an optical pickup having a spherical aberration correcting means 100 including a lens group for correcting spherical aberration of a light beam, the spherical aberration correcting means 100 includes a holder 2 for holding at least one lens 1a in the lens group, and a holder. 2 is slidably supported in the optical axis direction, and grease is applied to the sliding support portion of the holder 2 of the sliding support members 8a and 8b.
[Selection] Figure 1

Description

  The present invention relates to an optical pickup provided in an optical disc drive apparatus for optically recording / reproducing information.
  Optical recording / reproducing devices are being used for CDs that use lasers with a wavelength of 780 nm, DVDs that use lasers with a wavelength of 660 nm, and discs that use lasers with a wavelength of 405 nm. ing. At the same time, the density of NA is being increased by increasing the NA from 0.45 for CD to 0.6 for DVD.
  As described above, when the wavelength is shortened and the NA is increased, the tolerance for various optical characteristics is reduced, and the spherical aberration caused by the deviation of the cover glass thickness of the recording medium becomes unacceptable. Is required.
  One of the spherical aberration correction means is called a beam expander. The beam expander has a lens group composed of a combination of a convex lens and a concave lens, and adjusts the degree of light focusing and diffusion by adjusting the lens interval in the lens group. Therefore, if the degree of focusing / diffusion of light incident on the objective lens is changed using a beam expander, it is possible to correct spherical aberration and obtain good optical characteristics.
  By the way, as a lens moving mechanism in the beam expander, for example, a bearing is provided in a holder for holding a lens, and this bearing is slidably supported on a shaft provided in a fixed portion, and electromagnetic driving means using a coil and a magnet. A configuration in which the holder is moved in the optical axis direction can be considered.
  However, with this lens moving mechanism, there is a merit that it is easy to reduce the size and cost, but there is a slight difference between the shaft and the bearing that slidably supports the holder in order to move the holder. There is a gap. For this reason, when vibration is applied to the apparatus, the holder vibrates accordingly, the light is shaken, and the detected signal may be adversely affected. Further, when the holder is moved, the holder may be tilted by the gap, which also has an adverse effect during adjustment.
  In order to solve such a problem, for example, a bearing is provided in a holder that holds a lens, and the bearing is slidably supported on a shaft provided in a fixed portion, and a coil, a magnetic piece, A magnet is attached to the fixed part facing the coil and the magnetic piece, and the bearing is constantly pressed against the shaft by the magnetic piece's attractive force by the magnet, and in that state, a current is passed through the coil. The holder is moved in the axial direction by the electromagnetic action with the magnet, and the holder is held at the moving position (for example, see Patent Document 1).
According to the lens moving mechanism disclosed in Patent Document 1, since the bearing provided in the holder is constantly pressed against the shaft provided in the fixed portion, the holder can be easily moved even if vibration is applied to the apparatus. Can be prevented. Moreover, since the pressing force of the bearing against the shaft is also acting during the movement of the holder, the tilt of the holder during the movement can be suppressed.
JP 2003-338069 A
  According to the lens moving mechanism disclosed in Patent Document 1, if the pressing force of the bearing provided on the holder with respect to the shaft provided on the fixed portion is increased, it can withstand greater vibration.
  However, this pressing force always acts as a force that prevents the holder from being driven by the magnetic force of the magnetic piece by the magnet. For this reason, when the pressing force is increased, the frictional force generated here is increased, which causes a problem that the smooth movement of the holder is hindered and precise control cannot be performed. Further, in order to overcome a large frictional force, it is necessary to increase the driving force of the holder, which causes a disadvantage that the holder is inclined greatly.
  Accordingly, an object of the present invention made in view of the above circumstances is to provide a high-performance optical pickup capable of smoothly moving a lens for correcting spherical aberration and precisely controlling the position.
The invention according to claim 1, which achieves the above object, includes a light source, an objective lens that focuses a light beam emitted from the light source on a recording surface of an optical recording medium, and an optical path between the light source and the objective lens. In an optical pickup having a spherical aberration correcting means that is disposed inside and has a lens group that corrects the spherical aberration of the light beam,
The spherical aberration correction means includes a holder that holds at least one lens of the lens group, a sliding support member that supports the holder so as to be slidable in the optical axis direction, and the holder of the sliding support member. And a grease applied to the sliding support portion.
  The invention according to claim 2 is the optical pickup according to claim 1, wherein the grease contains 50% or more of chemically synthesized oil.
  The invention according to claim 3 is the optical pickup according to claim 1 or 2, wherein the grease contains fluorine.
  The invention according to claim 4 is the optical pickup according to any one of claims 1 to 3, wherein the lens and the surface or ridge line of the holder are in contact with the first surface and the sliding support portion. The connecting portion connecting the second surface of the holder is configured with a plurality of surfaces.
  According to a fifth aspect of the present invention, in the optical pickup according to any one of the first to third aspects, the sliding support portion and 0.5 mm are disposed in the vicinity of the surface of the holder that contacts the sliding support portion. A third surface facing each other with the following gap is formed, and a connecting portion connecting the first surface where the lens and the surface or ridge line of the holder are in contact with the third surface is configured with a plurality of surfaces. It is characterized by this.
  According to a sixth aspect of the present invention, in the optical pickup according to any one of the first to third aspects, the sliding support member is fixed to a housing that holds at least one other lens in the lens group. A connecting portion that is provided integrally and connects the fourth surface of the housing with which the surface or ridgeline contacts the surface and the sliding support portion has a plurality of surfaces.
  According to a seventh aspect of the present invention, in the optical pickup according to the fourth aspect of the present invention, a surface in the vicinity of the first surface and a surface in the vicinity of the second surface constituting the connecting portion are provided on the holder. The connecting portion is provided with a step so as to be positioned differently in the moving direction.
  The invention according to claim 8 is the optical pickup according to claim 5, wherein a surface in the vicinity of the first surface and a surface in the vicinity of the third surface that constitute the connecting portion are provided on the holder. The connecting portion is provided with a step so as to be positioned differently in the moving direction.
  The invention according to claim 9 is the optical pickup according to claim 6, wherein the surface in the vicinity of the fourth surface constituting the connecting portion and the surface in the vicinity of the sliding support portion are formed by the holder. The connecting portion is provided with a step so as to be positioned differently in the moving direction.
  According to a tenth aspect of the present invention, in the optical pickup according to any one of the fourth to ninth aspects, a groove is provided in the connecting portion.
  According to an eleventh aspect of the present invention, in the optical pickup according to any one of the fourth to tenth aspects, a wall portion is provided in the connecting portion.
  The invention according to claim 12 is the optical pickup according to any one of claims 1 to 11, wherein the holder is provided with a seal member in contact with or close to the sliding support portion to 0.2 mm or less. It is characterized by this.
  According to a thirteenth aspect of the present invention, in the optical pickup according to the twelfth aspect, the seal member has elasticity.
  The invention according to claim 14 is the optical pickup according to claim 13, wherein the seal member is made of silicone rubber.
  According to a fifteenth aspect of the present invention, in the optical pickup according to the thirteenth aspect, the seal member is made of a polyester elastomer.
  The invention according to claim 16 is the optical pickup according to any one of claims 1 to 15, wherein at least one lens in the lens group and the sliding support portion are connected by a straight line. A partition wall member separating the lens and the sliding support portion is provided in a range intersecting with the straight line.
  According to a seventeenth aspect of the present invention, in the optical pickup according to the sixteenth aspect, the partition member has an expandable bellows portion.
  According to an eighteenth aspect of the present invention, in the optical pickup according to the sixteenth aspect, the partition member is a film and has a pleated portion.
  According to the first aspect of the present invention, the holder for holding the lens for correcting the spherical aberration can move smoothly with respect to the sliding support member with little influence of backlash, so that precise position control is possible. Thus, higher performance can be achieved.
  According to the invention of claim 2, the temperature characteristics of the grease can be improved.
  According to invention of Claim 3, a holder can be moved more smoothly.
  According to invention of Claim 4, adhesion of the grease to the lens hold | maintained at the holder can be prevented.
  According to the invention of claim 5, it is possible to further prevent the grease from adhering to the lens held by the holder.
  According to the sixth aspect of the present invention, it is possible to prevent the grease from adhering to the lens held in the housing.
  According to the inventions of claims 7 and 8, the adhesion of grease to the lens held by the holder can be further prevented.
  According to the invention of claim 9, it is possible to further prevent the grease from adhering to the lens held in the housing.
  According to the inventions of claims 10 and 11, the adhesion of grease to the lens can be further prevented.
  According to the twelfth aspect of the present invention, it is possible to prevent the grease from adhering to the lens held by the holder and to reduce the size of the spherical aberration correcting means.
  According to invention of Claim 13, adhesion of the grease to the lens hold | maintained at the holder can be prevented more.
  According to the inventions of claims 14 and 15, the performance of the seal member can be maintained for a long time.
  According to the invention of claim 16, it is possible to more reliably prevent the grease from adhering to the lens.
  According to the inventions of claims 17 and 18, the partition member can be made simple and inexpensive.
  Embodiments of an optical pickup according to the present invention will be described below with reference to FIGS.
(First embodiment)
1 to 6 show a first embodiment of the present invention. FIG. 1 is a diagram showing a configuration of an optical system of an optical pickup, and FIG. 2 is a top view showing a configuration of spherical aberration correcting means shown in FIG. 3 is a front view, FIG. 4 is a sectional view taken along line AA in FIG. 3, FIG. 5 is a sectional view taken along line BB in FIG. 3, and FIG. 6 is a sectional view taken along line CC in FIG. .
  In FIG. 1, linearly polarized laser light emitted from a semiconductor laser 101 as a light source is converted into parallel light by a collimator lens 102 and enters a polarization beam splitter 103 with, for example, P-polarized light. The polarization beam splitter 103 is formed with, for example, a P-polarized light transmittance of 80%, a P-polarized light reflectance of 20%, and an S-polarized light reflectance of 100%. The laser beam that is received and controlled by the emission power of the semiconductor laser 101 is transmitted through a laser beam whose optical path is bent by 90 degrees by the rising mirror 105, passes through the quarter-wave plate 106, and the optical recording medium 108 such as an optical disk by the objective lens 107. Is recorded on the recording surface 108a, and information is recorded or reproduced.
  In the reproduction of information, the reflected light from the recording surface 108a enters the polarization beam splitter 103 along the same path as the forward path. Here, since the return light from the optical recording medium 108 incident on the polarization beam splitter 103 is transmitted through the quarter-wave plate 106 twice in the forward path and the return path, the polarization direction is orthogonal to the forward path, and the polarization beam splitter 103 is reflected. The return light reflected by the polarization beam splitter 103 is received by the photodetector 110 through a toric lens 109 having a condensing function and an astigmatism generation function formed by joining a spherical lens and a cylindrical concave lens. Based on the output, a focus error, a tracking error, and an information reproduction signal are obtained by a known method.
  In this embodiment, in FIG. 1, a relay lens system including a lens 1b having a beam divergence function and a lens 1a having a beam convergence function is provided in a reciprocating optical path between the polarization beam splitter 103 and the rising mirror 105. A spherical aberration correction means 100 is provided.
  The spherical aberration correcting unit 100 fixes one or both of the lenses 1a and 1b, in this embodiment, the lens 1b on the semiconductor laser 101 side, and moves the lens 1a on the objective lens 107 side in the optical axis direction. The spherical aberration generated by the deviation of the cover glass thickness of the optical recording medium 108 is corrected.
  Hereinafter, the configuration of the spherical aberration correcting unit 100 will be described.
  In FIG. 5, the lens 1 a is bonded and fixed to a holder 2 made of a synthetic resin having good slidability such as PPS containing carbon fiber. As shown in FIG. 3, coils 3 a and 3 b are also fixed to the holder 2. The holder 2 is integrally formed with bearings 4 and 5. The shafts 8a and 8b, which are sliding support members, are inserted into the bearing portions 4 and 5, whereby the holder 2 is slidably supported by the bearing portions 4 and 5 and the shafts 8a and 8b so as to be movable in the X direction. Will be.
  The bearing portion 4 is a main bearing, and has convex portions 7a to 7d that are arc-shaped in cross section as shown in FIG. The vertices of the arc-shaped convex portions 7a to 7d (portions protruding inward) are on a circle having a diameter 5 μm to tens of μm larger than the diameter of the shaft 8a, and come into contact with the shaft 8a. It has become. Since the bearing 4 has a diameter that is 5 to several tens μm larger than the shaft 8a, the bearing 4 can slide in the gap with respect to the shaft 8a. The portions other than the convex portions 7a to 7d of the bearing portion 4 have a shape of a circle 20 having a diameter that is, for example, 0.3 mm larger than the diameter of the shaft 8a. Thereby, gaps 19a to 19d are formed between portions of the bearing portion 4 that are not in contact with the shaft 8a. Therefore, when dust or the like enters the bearing portion 4 during use of the apparatus, the gaps 19a to 19d are formed. Can escape. Therefore, it is possible to prevent the holder 2 from sliding due to the bearing portion 4 being clogged with dust, and to improve the reliability. The bearing portion 4 has a length indicated by an arrow 4 ′ in FIG. 5 in the X direction.
  The bearing portion 5 is a driven bearing and has a shape in which a circle 21 is connected by straight lines 6a and 6b in cross section as shown in FIG. The distance between the straight lines 6a and 6b is 5 μm to several tens of μm larger than the diameter of the shaft 8b, and is in contact with the shaft 8b, so that the bearing portion 5 can slide with respect to the shaft 8b through the gap. ing. The portion of the bearing portion 5 that is in contact with the shaft 8b, that is, the portion that becomes the straight lines 6a and 6b in cross section, is provided only in the range of the arrow 5 'in FIG. In FIG. 5, for the sake of clarity, the portion having the straight lines 6a and 6b in the cross section is rotated 90 degrees with respect to the center of the shaft 8b so that the narrow portion appears in the cross section. The cross-sectional shape of the other part of the bearing portion 5 is a circle 21. The circle 21 has a diameter that is, for example, 0.3 mm larger than the diameter of the shaft 8b, and the shaft 8b and the bearing portion 5 are not in contact with each other outside the range of the arrow 5 '. Thus, the portion of the bearing portion 5 that contacts the shaft 8b is shorter than the bearing portion 4 in the X direction, and the shaft 8b is restricted only in the direction orthogonal to the straight lines 6a and 6b, and not restricted in the linear direction. As a result, if the parallelism of the shafts 8a and 8b and the gap between them are small, they can be absorbed.
Lithium soap grease containing chemically synthesized oil is applied to the shafts 8a and 8b on the peripheral surface which is a sliding support portion. This is a chemical composition oil contained in a lithium soap-based sponge structure. The grease is applied in an amount of 0.002 to 0.005 mg / mm 2 based on the surface area of the shafts 8a and 8b.
  The shafts 8a and 8b are fixed to a housing 9 made of a highly rigid synthetic resin such as a glass fiber-containing liquid crystal polymer. As shown in FIG. 5, the lens 1 b is also bonded and fixed to the housing 9.
  The housing 9 is fixed to an iron base 11. The base 11 is provided with rising portions 12a, 12b, 13a, 13b. Magnets 14a, 14b are bonded to the rising portions 12a, 12b, and the rising portions 13a, 13b are formed of coils 3a, 3b. It is arranged inside. As shown in FIG. 2, an iron auxiliary yoke 15a is fixed so as to connect the rising portion 12a and the rising portion 13a. Similarly, an iron auxiliary yoke 15b is fixed so as to connect the rising portion 12b and the rising portion 13b. In FIG. 3, the auxiliary yokes 15a and 15b are not shown.
  Ita 18 is fixed to the housing 9 and the base 11, and a flexible substrate 16 having a bent portion 17 is disposed between the ita 18 and the holder 2. Coils 3 a and 3 b are connected to the flexible substrate 16. The flexible substrate 16 is connected to an external electric circuit.
  Next, the operation of the present embodiment configured as described above will be described.
  In the present embodiment, spherical aberration caused by variations in the cover glass thickness of the optical recording medium 108 is also detected based on the output of the photodetector 110 shown in FIG. Here, when spherical aberration is detected, current is passed through the coils 3a and 3b, and the lens 1a is moved together with the holder 2 in the X direction to correct the spherical aberration. At this time, the grease applied to the shafts 8a and 8b improves the slidability with the bearings 4 and 5 and improves the movement. In addition, the soap base portion of the grease serves as a cushion, and the tilt due to the gap for sliding is prevented from occurring. In addition, the soap base portion prevents the tilt when tilting by the gap, so that the tilt amount can be reduced or the time during which the tilt occurs can be lengthened. In this way, the influence on the signal can be reduced by reducing the inclination, and the time for the inclination to be increased can provide a time margin for the servo system and the like to follow. Can be small. This is the same when external vibration or the like is applied to the apparatus. The amount of vibration of the holder 2 can be reduced by the grease and the shaking reaction can be delayed, so that the influence on the signal can be reduced.
  As described above, according to the present embodiment, the grease is applied to the shafts 8a and 8b, so that the influence of the play due to the gap for sliding can be reduced and the movement can be smoothly performed, and the high performance apparatus. It can be. Further, by using a synthetic oil as the oil contained in the grease, the temperature characteristics can be improved compared to the case of using mineral oil or the like. It is particularly effective to use 50% or more of chemically synthesized oil. Further, by adding fluorine to the grease, the slidability can be further improved and the movement of the holder 2 can be improved.
(Second Embodiment)
FIGS. 7 and 8 show a second embodiment of the present invention. FIG. 7 is a front view corresponding to FIG. 3 of the first embodiment, and FIG. FIG. 6 is a cross-sectional view corresponding to FIG. 5 of the first embodiment, and the same components as those of the first embodiment are denoted by the same reference numerals. Note that the orientation of the cross section in the range of the arrow 5 'in FIG. 8 is changed and shown in the same manner as in the first embodiment.
  In 1st Embodiment, although the circular-arc-shaped convex parts 7a-7d which contact the shaft 8a of the bearing part 4 were formed so that the holder 2 might be penetrated to a X direction, in this Embodiment, as shown in FIG. The arc-shaped convex portions 7a to 7d are formed to have a length indicated by an arrow 4 ". That is, both end portions in the X direction of the holder 2 have a circular cross section having a diameter 0.4 mm larger than the diameter of the shaft 8a, for example. The portions 22a and 22b are escape portions so as not to touch the shaft 8a, and the other configurations and operations are substantially the same as those of the first embodiment.
As described in the first embodiment, by applying grease to the sliding part, it is possible to reduce the influence of the play due to the gap for sliding, and to make the movement smooth, and to make a high-performance device. Can do. However, if the amount of grease applied is too large, it may be scattered when the holder is moved and attached to the surface of the lens 1a to deteriorate the optical characteristics. In order to prevent this, in the first embodiment, the amount of grease applied is 0.002 to 0.005 mg / mm 2 , but it is relatively difficult to control the amount of grease applied, and the amount applied is small. Therefore, it is desirable to increase the amount of application, and the upper limit is more than 0.005 mg / mm 2 because the amount of grease is subtle. Control becomes unnecessary and workability is improved.
  In the present embodiment, a convex portion which is a surface 24 (first surface) with which the lens 1a of the holder 2 is in contact and a surface (second surface) with which the shaft 8a to which grease is applied is in contact. 7a to 7d are not connected to a single plane, but a surface 23 in contact with the surface 24, and a circular cross-section portion (side surface) 22a that forms a relief portion so as not to touch the shaft 8a (third Surface) and a surface 25 connecting the surface 22a and the convex portions 7a and 7d. Also on the shaft 8b side, a surface (second surface) having straight lines 6a and 6b in a cross section where the surface 24 of the holder 2 in contact with the lens 1a and the shaft 8b to which grease is applied is in contact. Are not a single plane, but a surface 23 in contact with the surface 24, a circular cross section (side surface) 21 (third surface) that does not touch the shaft 8b, and the surface 21 and the cross section. It consists of three surfaces, a surface 26 connecting the surfaces having straight lines 6a and 6b.
Thus, if the connection part which connects the surface 24 where the lens 1a of the holder 2 is in contact with the surface where the shafts 8a and 8b to which the grease is applied is in contact is not a single plane, When the amount of grease applied is greater than 0.005 mg / mm 2 , the grease applied to the shafts 8a, 8b is the surfaces 25, 22a, 26, 21 near the surfaces in contact with the shafts 8a, 8b. Therefore, it is possible to prevent the lens 1a from coming into contact with the surface 24, so that the grease can be prevented from scattering to the lens 1a, and the optical characteristics can be prevented from deteriorating.
  In particular, in the present embodiment, the connecting portion that connects the surface 24 in contact with the lens 1a and the surface in contact with the shaft 8a is the surface 23 on the lens 1a side and the surface 25 on the shaft 8a side. 25 is not the same position in the moving direction of the holder 2 but is connected with a step, so that it is possible to more reliably prevent grease from scattering from the shaft 8a to the lens 1a. Similarly, on the side of the shaft 8b, the surface 1 on the lens 1a side and the surface 26 on the side of the shaft 8b have a level difference, so that the scattering of grease from the shaft 8b to the lens 1a can be prevented more reliably. Can do.
  Note that the effect of preventing the grease from scattering to the lens 1a has a single connecting portion that connects the surface 24 in contact with the lens 1a and the surface in contact with the shafts 8a and 8b to which the grease is applied. For example, for the shaft 8a, the surface 23 and the surface 25 may be connected by a single curved surface.
(Third embodiment)
FIGS. 9 and 10 show a third embodiment of the present invention. FIG. 9 is a front view showing the configuration of the spherical aberration correcting means, corresponding to FIG. 3 of the first embodiment, and FIG. FIG. 9 is a cross-sectional view taken along line EE of FIG. 9, corresponding to FIG. 5 of the first embodiment, and the same components as those of the first embodiment are denoted by the same reference numerals. Note that the orientation of the cross section in the range of the arrow 5 'in FIG. 10 is changed as in the case of the first embodiment.
  In the first embodiment, the X + direction end of the holder 2 has a simple planar shape. However, in the present embodiment, the vicinity of the attachment portion of the lens 1a is convex, and the surface 30 and the surrounding surface 28 of that portion are convex. Has a step in the X direction. In addition, the housing 9 is not a simple planar shape at the end in the X + direction, and the vicinity of the attachment portion of the lens 1b is convex, and the surface 33 and the surrounding surface 31 have a step in the X direction. Other configurations and operations are substantially the same as those in the first embodiment.
  Thereby, in this Embodiment, convex part 7a-7d which is the surface (2nd surface) which the surface 24 where the lens 1a of the holder 2 is contacting, and the axis | shaft 8a to which grease is applied is contacting. Is not a single flat surface, but includes three surfaces: a surface 30 in contact with the surface 24, a side surface 29 thereof, and a surface 28 in contact with the convex portions 7a to 7d. Similarly, on the side of the shaft 8b, a straight line 6a in a cross section, which is a surface (second surface) with which the surface 8 of the holder 2 is in contact with the lens 1a and the shaft 8b with grease applied, In addition to the connecting portion that connects the surface having 6b, there is also a connecting portion that connects the surface 24, the shaft 8b to which grease is applied, and the surface 21 (third surface) facing each other with a gap of 0.3 mm. Not a single plane. That is, the connecting portion that connects the surface 24 and the surface 21 includes three surfaces: a surface 30 that is in contact with the surface 24, a side surface 29 thereof, and a surface 28 that is in contact with the surface 21.
  Here, when a large amount of grease is applied to the shaft 8b, the grease adheres to the surface of the shaft 8b with a thickness. At this time, the grease adheres in such a manner that the grease is scraped to the surface 26 in contact with the surface having the straight lines 6a and 6b in the cross section in contact with the shaft 8b, and is opposed to the shaft 8b with a narrow gap. There is also a possibility of adhering to the surface 21 and the periphery of the surface 21 of the surface 28 in contact with the surface 21. In particular, when the gap between the surface 21 and the shaft 8b is 0.5 mm or less, there is a high possibility that grease will adhere. In the present embodiment, the surface 21 facing the shaft 8b with such a possible gap of 0.3 mm and the surface 24 in contact with the lens 1a of the holder 2 are not a single plane. By forming the three surfaces 30, 29, and 28 so as to be connected, it is possible to prevent the grease from adhering to the lens 1 a even when the amount of grease is large.
  In the present embodiment, the surfaces facing each other with a narrow gap on the shaft 8a side are the surfaces 35a to 35d in FIG. 9, but the surface 28 is in contact with the shaft 8a across the ridge line. It is the same as the surface that is in contact with the projecting convex portions 7a to 7d across the ridge line, and also on the shaft 8a side, the opposing surfaces 35a to 35d with a narrow gap and the lens 1a of the holder 2 are in contact. The connected surface 24 is not a single plane but is connected by three surfaces 30, 29, and 28.
  Further, in the present embodiment, the surface 34 (fourth surface) of the housing 9 where the ridge line is in contact with the other lens 1b constituting the relay lens system, and the shafts 8a and 8b coated with grease are provided. The connecting portion is not a single flat surface, but is composed of three surfaces: a surface 33 in contact with the surface 34, a side surface 32 thereof, and a surface 31 in contact with the shafts 8a and 8b. Thereby, adhesion of grease to the lens 1b can be prevented, and deterioration of optical characteristics can be prevented. In the case of the housing 9, it is more likely that the grease accumulates in a mountain shape near the contact portion of the shafts 8 a and 8 b with the housing 9, and the grease reaches the lens 1 b from there. With regard to this as well, by providing a step rather than a single flat surface, the spread can be stopped at the boundary, and adhesion of grease to the lens 1b can be prevented.
(Fourth embodiment)
11 to 13 show a fourth embodiment of the present invention. FIG. 11 is a front view showing the configuration of spherical aberration correcting means, FIG. 12 is a sectional view taken along line FF in FIG. 11, and FIG. FIG. 12 is a cross-sectional view taken along line GG, and parts having the same role as in the first embodiment are denoted by the same reference numerals.
  In FIG. 12, the lens 1a is bonded and fixed to a holder 2 made of aluminum or the like. As shown in FIG. 13, an annular magnet 42 is also fixed to the holder 2. As shown in FIG. 12, the magnet 42 is magnetized so that the outer side is the S pole and the inner side is the N pole. The holder 2 has a circular cross section and a cylindrical shape, but the side surface portion 46 has a small surface roughness. A wall portion 48 is provided on the surface at the end of the X + direction of the holder 2 so as to divide the surface. As shown in FIG. 11, the wall portion 48 has an annular shape, and the surface at the end in the X + direction is divided into an outer surface 47 a and an inner surface 47 b by the wall portion 48.
The holder 2 is inserted into a hole 44 formed on the inner side of the housing 9 made of synthetic resin having good sliding properties such as PPS containing carbon fiber. The hole 44 has a circular cross section and a small surface roughness on the peripheral surface, and the diameter is several μm to several tens μm larger than the outer diameter of the holder 2. The holder 2 is supported by the gap so as to be slidable in the X direction with respect to the housing 9. That is, in the present embodiment, the housing 9 constitutes a sliding support member of the holder 2 and the hole 44 constitutes a sliding support portion. Here, about 0.002 to 0.005 mg / mm 2 of grease is applied to the peripheral surface of the hole 44 of the housing 9. In FIG. 12, the gap 41 is shown larger for convenience of explanation. After the holder 2 is inserted into the hole 44 on the X + direction end surface of the housing 9, an ita 45 is attached to prevent the housing 9 from coming off.
  The lens 1b is also bonded and fixed to the housing 9. A groove 50 is provided in an annular shape on the surface at the end of the lens 1b in the X + direction, whereby the surface at the end of the lens 1b in the X + direction is divided into a surface 49a and a surface 49b.
  An annular coil 43 is further wound around the housing 9. A flexible substrate (not shown) is connected to the coil 43 and further connected to an external electric circuit.
  Next, the operation of the present embodiment configured as described above will be described.
  In the present embodiment, unlike the first embodiment, the magnet 42 is attached to the movable holder 2, but by passing an electric current through the coil 43, a force is exerted on the magnet 42 by electromagnetic force, and the holder 2. Can be moved. When spherical aberration is detected, by passing a current through the coil 43, the spherical aberration can be corrected by moving the lens 1a as in the first embodiment. Other operations are the same as those in the first embodiment.
  In the present embodiment, the connection connecting the surface 24 of the holder 2 that is in contact with the lens 1a and the side surface 46 (second surface) that is in contact with the peripheral surface of the hole 44 to which grease is applied. The portion is not a single plane, but is a surface 47a, 47b divided by the wall 48. Thus, by dividing the wall 47 into the surfaces 47a and 47b, the spread of grease along the surface can be prevented, and the wall portion 48 can also prevent splashing, thereby preventing the grease from adhering to the lens 1a. it can.
  Also for the lens 1b, the connecting portion that connects the surface 34 (fourth surface) of the housing 9 where the ridge line is in contact with the lens 1b and the peripheral surface of the hole 44 to which the grease is applied is also a single plane. Since the groove portion 50 divides the surface 49a and the surface 49b, the spread of grease along the surface can be prevented and the adhesion of grease to the lens 1b can be prevented. In addition, in the case of the groove part 50, since it does not become convex like the wall part 48, there exists an advantage that it is easy to reduce in size.
  In this embodiment, the wall portion 48 is provided on the lens 1a side and the groove portion 50 is provided on the lens 1b side. However, the opposite may be applied, for example, both may be wall portions, or as in the second embodiment. It goes without saying that various combinations such as combining various steps are possible.
(Fifth embodiment)
FIGS. 14 to 16 show a fifth embodiment of the present invention. FIG. 14 is a front view showing the configuration of the spherical aberration correcting means, corresponding to FIG. 3 of the first embodiment, and FIG. 14 is a cross-sectional view of the HH line main part corresponding to FIG. 5 of the first embodiment, and FIG. 16 is an explanatory view of a modified example. The same parts as those in the first and second embodiments are the same Reference numerals are attached. As in the figure of the first embodiment, the orientation of the cross section in the range of the arrow 5 'in FIG. 15 is changed.
  Although this embodiment is substantially the same as the second embodiment, recesses 53 a to 53 d are provided at both ends in the X direction of the bearing portions 4 and 5 of the holder 2. Further, as shown in FIGS. 14 and 15, annular thin seal members 52a to 52d made of silicone rubber are fixed to the portion. The central hole of the seal members 52a to 52d is passed through the shafts 8a and 8b. The central hole of the seal members 52a to 52d is smaller than the diameter of the shafts 8a and 8b, for example, by about 0.1 mm. However, the seal member is soft, so that the movement of the holder 2 is not hindered.
  A portion having a large diameter other than the sliding range 4 ″ and 5 ′ of the bearing portions 4 and 5 of the holder 2 forms spaces 54a to 54d surrounded by seal members 52a to 52d. Are formed with thin holes 51a to 51d (51d not shown) reaching these spaces 54a to 54d.
  In the present embodiment, the grease is not directly applied to the shafts 8a and 8b, but the shafts 8a and 8b are inserted into the bearing portions 4 and 5 before assembling. At this time, the seal members 52a to 52d are also attached. Thereafter, an appropriate amount of grease is inserted from the holes 51a to 51d into the spaces 54a to 54d using an injection needle. After the insertion, when the holder 2 is rotated several times along the shafts 8a and 8b, the grease wraps around the sliding ranges 4 ″ and 5 ′ between the shafts 8a and 8b and the bearings 4 and 5. Other configurations and The operation is almost the same as in the second embodiment.
  In the present embodiment, the space of the bearings 4 and 5 to which the grease is applied is separated from the space where the lenses 1a and 1b are provided by the seal members 52a to 52d. Therefore, adhesion of grease to the lenses 1a and 1b can be more reliably prevented. Strictly speaking, when the holder 2 moves, the contact portion between the seal members 52a to 52d and the shafts 8a and 8b bends, and the grease passes from the gap to the outside of the seal members 52a to 52d (based on the bearing portions 4 and 5). Even if it does not come out, the oil content of the grease may not be completely sealed and may come out of the sealing members 52a to 52d. However, the amount is very small compared to the amount of grease applied to the shaft, and the possibility of splashing is low, which is not a problem. In addition, since the sealing members 52a to 52d are made of silicone rubber and hardly deteriorate, the performance can be maintained for a long time.
  The sealing members 52a to 52d need not be silicone rubber as long as they are soft members. However, it is preferable that the sealing members 52a to 52d are elastic members in terms of preventing the scattering of grease, and a material that is not violated by grease. Is good. As such a material, a polyester elastomer can be used other than silicone rubber, and similarly, performance can be maintained over a long period of time.
  Further, the seal members 52a to 52d may be provided with a gap 55 between the seal member 52 'and the shaft 8 as shown in FIG. 16 without being brought into contact with the shafts 8a and 8b. In this case, the grease comes out from the gap 55, but inside the seal member 52 ′ (with reference to the bearing portion), even if the grease 56 collects, the grease comes out only by the width of the gap 55 outside the seal member 52 ′. Since it is not leveraged, the amount and thickness of the grease that is exposed to the outside is small, and the effect of reducing the possibility of grease scattering is sufficiently obtained. At this time, if the size of the gap 55 is large, there is no effect, and the smaller the size, the greater the effect. When the gap 55 is provided as described above, there is no problem even if the seal member 52 'is not elastic.
(Sixth embodiment)
FIGS. 17 to 20 show a sixth embodiment of the present invention. FIG. 17 is a cross-sectional view showing the configuration of the spherical aberration correcting means, corresponding to FIG. 12 of the fourth embodiment, and FIG. FIGS. 19 and 20 are diagrams for explaining the effects of the present embodiment, and FIG. 19 and FIG. 20 are explanatory diagrams of modified examples. Components having the same functions as those of the fourth embodiment are denoted by the same reference numerals.
  In the present embodiment, unlike the fourth embodiment, as shown in FIG. 17, the housing 9 includes a housing 60a that holds the lens 1b and a housing 60b that has a hole portion 44 into which the holder 2 is inserted. It has become. That is, in the present embodiment, the housing 60b constitutes the sliding support member of the holder 2, and the hole 44 constitutes the sliding support portion.
  Further, a film-like member 59 having a pleated portion which is a partition member is fixed between the holder 2 and the X + end of the housing 60b. The film-like member 59 has an annular shape similar to the lens 1a mounting portion of the holder 2 and the housing 60b, and annular members 57 and 58 are fixed to both ends. The annular member 57 is attached to the housing 60b, and the annular member 58 is attached to the housing 60b. It is fixed to the holder 2. By this film-like member 59, the space 66 where the lens 1a is located is separated from the space 64 of the hole 44 where grease is applied. The film-like member 59 is made of a silicone rubber or the like.
  A film-like member 63 having a fold portion as a partition member is also fixed between the X-end of the holder 2 and the X + end of the housing 60a. The film-like member 63 also has an annular shape similar to the attachment portion of the holder 2 and the lens 1b of the housing 60a. The annular members 61 and 62 are fixed to both ends. The annular member 61 is the holder 2 and the annular member 62 is the annular member 62. It is fixed to the housing 60a. By this film-like member 63, the space 67 where the lens 1b is located is separated from the space 65 of the hole 44 where the grease is applied. The film member 63 is also made of silicone rubber or the like.
  In assembling, the annular members 57 and 58 are fixed to the membrane member 59 in advance, and the annular members 61 and 62 are fixed to the membrane member 63. Next, the annular members 58 and 61 are fixed to the holder 2 and inserted into the housing 60 b from the X-end of the holder 2. Needless to say, the lens 1a and the magnet 42 are fixed to the holder 2 before that.
  When the holder 2 is inserted into the housing 60b, an appropriate amount of grease is applied to the housing 60b. The grease application operation can be performed before the holder 2 is inserted. Thereafter, the annular member 57 is fixed to the housing 60b. Next, the annular members 62 are fixed to the housing 60a in a state in which the film-like members 59 and 63 are extended to extend the annular member 62 out of the housing 60b. The housing 60a is fixed to the housing 60b.
  In the present embodiment, as shown in FIG. 18, the film-like member 59 is provided so as to intersect with a straight line 68a and a straight line 68b that connect the lens 1a and the peripheral surface of the hole 44 coated with grease. Can be isolated from the lens 1a, and adhesion of grease to the lens 1a can be prevented. Thus, since the space 66 with the lens 1a and the space 64 of the hole 44 where the grease is applied are completely separated, the effect of preventing adhesion is higher than in the first to fifth embodiments. Thus, adhesion can be prevented more reliably.
  Also for the lens 1b, as shown in FIG. 18, the film-like member 63 is provided so as to intersect with a straight line 69a and a straight line 69b that connect the lens 1b and the peripheral surface of the hole 44 coated with grease. Similarly, the adhesion of grease to the lens 1b can be prevented more reliably.
  That is, when the grease scatters, it often flies linearly from the grease application portion, but as in the present embodiment, the lens 1a, 1b and the peripheral surface of the hole 44 which is the grease application portion If the film-like members 59 and 63 that separate the two are provided so as to intersect with the straight line connecting the two, the scattered grease can be reliably prevented from adhering to the lenses 1a and 1b, and a great effect can be obtained. Also, by separating the pleated membrane members 59 and 63, the space between the two can be completely separated, and even if a large amount of liquid oil oozes out from the grease, it will not be transmitted to the lens. .
  The partition member may be an expansion / contraction mechanism having a bellows portion 70 made of synthetic resin or the like, as shown in FIG. 19, instead of the film-like members 59 and 63 having pleats. Moreover, as shown in FIG. 20, although it can also be set as the expansion-contraction mechanism which combines the cylindrical members 71a-71c from which a dimension differs little by little, in terms of easiness to make, it is a film-like member with a fold or a bellows part. It can be easily and inexpensively configured to expand and contract.
  Needless to say, the present embodiment is not limited to the combination with the fourth embodiment but can be applied to the first embodiment.
  The present invention is not limited to the above-described embodiment, and many variations or modifications are possible. For example, the cross section of the sliding portion is not limited to a circle, but may be a square or the like. Further, the above embodiments can be combined as appropriate, and may be applied only to a part of lenses constituting the relay lens system.
It is a figure which shows the structure of the optical system of the optical pick-up in 1st Embodiment of this invention. It is a top view which shows the structure of the spherical aberration correction means shown in FIG. Similarly, it is a front view. FIG. 4 is a sectional view taken along line AA in FIG. 3. Similarly, it is a BB line principal part sectional view. Similarly, it is CC sectional view taken on the line. It is a front view which shows the structure of the spherical aberration correction means in 2nd Embodiment of this invention. FIG. 8 is a cross-sectional view taken along the line DD of FIG. 7. It is a front view which shows the structure of the spherical aberration correction means in 3rd Embodiment of this invention. FIG. 10 is a cross-sectional view of the main part of line EE in FIG. It is a front view which shows the structure of the spherical aberration correction means in 4th Embodiment of this invention. It is the FF sectional view taken on the line of FIG. It is the GG sectional view taken on the line of FIG. It is a front view which shows the structure of the spherical aberration correction means in 5th Embodiment of this invention. It is a HH line principal part sectional view of Drawing 14. It is a figure for demonstrating the modification of 5th Embodiment. It is sectional drawing which shows the structure of the spherical aberration correction means in 6th Embodiment of this invention. It is a figure for demonstrating the effect of 6th Embodiment. It is a figure for demonstrating the modification of 6th Embodiment. Similarly, it is a figure for demonstrating the modification of 6th Embodiment.
Explanation of symbols
DESCRIPTION OF SYMBOLS 1a, 1b Lens 2 Holder 3a, 3b Coil 4,5 Bearing part 8a, 8b Shaft 7a-7d Convex part 9 Housing 11 Base 12a, 12b, 13a, 13b Standing part 14a, 14b Magnet 15a, 15b Auxiliary yoke 16 Flexible substrate 18 Ita 19a to 19d Clearance 21, 22a Surface (third surface)
23, 25, 26 planes 24 planes (first plane)
28-33 surface 34 surface (fourth surface)
42 Magnet 43 Coil 44 Hole 46 Side (second surface)
45 Ita 47a, 47b, 49a, 49b Surface 48 Wall 50 Groove 51a-51d Hole 52a-52d Seal member 53a-53d Recess 54a-54d Space 56 Grease 57, 58 Annular member 59 Film-like member 60a, 60b Housing 61, 62 Annular member 63 Film-like member 70 Bellows 71a to 71c Cylindrical member 100 Spherical aberration correcting means 101 Semiconductor laser 102 Collimator lens 103 Polarizing beam splitter 104 Monitor photodetector 105 Rising mirror 106 1/4 wavelength plate 107 Objective lens 108 Optical recording medium 108a Recording surface 109 Toric lens 110 Photodetector

Claims (18)

  1. A light source, an objective lens for condensing the light beam emitted from the light source on the recording surface of the optical recording medium, and an optical path between the light source and the objective lens are arranged to correct spherical aberration of the light beam. In an optical pickup having spherical aberration correction means comprising a lens group that
    The spherical aberration correction means includes a holder that holds at least one lens of the lens group, a sliding support member that supports the holder so as to be slidable in the optical axis direction, and the holder of the sliding support member. And a grease applied to the sliding support portion.
  2.   The optical pickup according to claim 1, wherein the grease contains 50% or more of chemically synthesized oil.
  3.   The optical pickup according to claim 1, wherein the grease contains fluorine.
  4.   A connecting portion that connects the first surface of the holder that contacts the lens or the surface or ridge line and the second surface of the holder that contacts the sliding support portion is configured with a plurality of surfaces. The optical pickup according to any one of claims 1 to 3.
  5.   In the vicinity of the surface of the holder that contacts the sliding support portion, a third surface is formed opposite the sliding support portion with a gap of 0.5 mm or less, and the lens of the holder contacts the surface or ridgeline. The optical pickup according to any one of claims 1 to 3, wherein a connecting portion that connects the first surface to be connected to the third surface is configured with a plurality of surfaces.
  6.   The sliding support member is fixed or integrally provided on a housing that holds at least one other lens in the lens group, and a fourth surface that contacts a surface or a ridge line with the lens of the housing, and the sliding The optical pickup according to any one of claims 1 to 3, wherein the connecting portion connecting the support portion is configured with a plurality of surfaces.
  7.   A step is provided in the connecting portion so that a surface in the vicinity of the first surface constituting the connecting portion and a surface in the vicinity of the second surface are positioned differently in the moving direction of the holder. The optical pickup according to claim 4, wherein:
  8.   A step is provided in the connecting portion so that the surface in the vicinity of the first surface constituting the connecting portion and the surface in the vicinity of the third surface are positioned differently in the moving direction of the holder. The optical pickup according to claim 5, wherein:
  9.   A step is provided in the connecting portion so that the surface in the vicinity of the fourth surface constituting the connecting portion and the surface in the vicinity of the sliding support portion are positioned differently in the moving direction of the holder. The optical pickup according to claim 6, wherein:
  10.   The optical pickup according to claim 4, wherein a groove portion is provided in the connecting portion.
  11.   The optical pickup according to claim 4, wherein a wall portion is provided in the connecting portion.
  12.   The optical pickup according to any one of claims 1 to 11, wherein a seal member is provided on the holder so as to be in contact with the sliding support portion or close to 0.2 mm or less.
  13.   The optical pickup according to claim 12, wherein the seal member has elasticity.
  14.   The optical pickup according to claim 13, wherein the seal member is made of silicone rubber.
  15.   The optical pickup according to claim 13, wherein the seal member is made of a polyester elastomer.
  16.   When at least one lens of the lens group and the sliding support portion are connected by a straight line, a partition member is provided to separate the lens and the sliding support portion in a range intersecting with the straight line. The optical pickup according to any one of claims 1 to 15.
  17.   The optical pickup according to claim 16, wherein the partition member has a bellows part that can be expanded and contracted.
  18.   The optical pickup according to claim 16, wherein the partition member is a film and has a pleat portion.
JP2004089987A 2004-03-25 2004-03-25 Optical pickup Pending JP2005276355A (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2010009666A (en) * 2008-06-26 2010-01-14 Nidec Copal Corp Device of driving optical element
JP2010225248A (en) * 2009-03-25 2010-10-07 Hitachi Media Electoronics Co Ltd Optical pickup device

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2010009666A (en) * 2008-06-26 2010-01-14 Nidec Copal Corp Device of driving optical element
JP2010225248A (en) * 2009-03-25 2010-10-07 Hitachi Media Electoronics Co Ltd Optical pickup device

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