JP2007042230A - Optical pickup and optical disk device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical pickup and an optical disk device capable of preventing the output of a DVD from being greater than before even when a 2-wavelength semiconductor laser beam source is used. <P>SOLUTION: This optical pickup 8 is provided with a laser beam source 1 having emission points 1a and 1b disposed close to each other to respectively emit the laser beam 1 of a wavelength λ1 and the laser beam of a wavelength λ2(λ1<λ2), a hologram 5a for separating the laser beams of the wavelengths λ1 and λ2 into a luminous flux for a 1-beam method tracking control signal and a luminous flux for a focus control signal, and a light receiving sensor 8 having a photodetecting surface for detecting each of the luminous fluxes separated by the hologram 5a. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an optical pickup employed in an optical disk device mounted on a personal computer (hereinafter referred to as a PC), particularly a notebook PC, and an optical disk device mounted with the optical pickup.

  Conventionally, optical pickups mounted on optical disk devices have increased the types of optical disks that can be recorded and reproduced, and have increased functions. Initially, only CD and CD-ROM playback was performed, but recording and playback on CD-R / RW, DVD-ROM playback, and recording and playback on various recording DVDs became possible. On the other hand, there is a strong demand for cost reduction, and in order to reduce optical components, a two-wavelength semiconductor laser in which light emitting points having two different wavelengths are contained in one package has been adopted.

  FIG. 9 is a configuration diagram of an optical system of a conventional optical pickup.

  The laser light source module 111 includes a laser light source 101 and a light receiving sensor 109. The laser light source 101 is a two-wavelength semiconductor laser provided with a light emitting point that emits laser light having a wavelength λ1 (about 650 nm) for DVD and a light emitting point that emits laser light having a wavelength λ2 (about 780 nm) for CD. It is a light source and is mounted in the package of the laser light source module 111. The diffractive element 102 has a substrate formed of a substantially rectangular parallelepiped transparent optical glass. A surface of the substrate facing the laser light source 101 is provided with a diffraction grating that separates the light emitted from the laser light source 101 into three beams: a central main beam and side beams on both sides. The light beam separated into three beams by the diffraction grating is used for CD tracking control. The beam splitter 103 includes a base formed of optical glass or optical plastic, and a polarization separation film on the surface of the base on the laser light source 101 side. The collimating lens 104 and the objective lens 107 are made of optical glass or optical plastic. The rising mirror 105 is formed by forming a total reflection film such as a dielectric multilayer film on the surface of optical glass or optical plastic. The hologram element 106 is obtained by bonding a hologram 106a and a quarter wavelength plate 106b. The optical disk 108 is a CD-type or DVD-type recording medium. The light receiving sensor 109 is housed in the package of the laser light source module 111, receives the laser light emitted from the laser light source 101 and reflected by the recording surface of the optical disk 108 by each light receiving element, converts it into a predetermined electric signal, and outputs it. . The front light monitor 110 receives the laser light emitted from the laser light source 101 slightly transmitted through the beam splitter 103, converts the laser light into an electrical signal corresponding to the light amount, and outputs the electrical signal.

  When a laser beam having a wavelength λ 1 for DVD and a laser beam having a wavelength λ 2 for CD are emitted from the laser light source 101, they enter the diffraction element 102. The diffraction element 102 originally separates the laser beam having the wavelength λ2 into three beams, and separates the laser beam having the wavelength λ2 into three beams. Similarly, laser light having a wavelength λ1 that does not need to be separated is also separated into three beams. The laser beam separated by the diffraction element 102 enters the beam splitter 103. The polarization separation film on the surface of the beam splitter 103 reflects most of the laser light toward the optical disc 108 and transmits part of the laser light toward the front light monitor 110. The collimating lens 104 converts the laser light that has been diverging light into substantially parallel light. The raising mirror 105 is raised so that the optical path of the laser beam, which has been substantially parallel to the recording surface of the optical disc 108 until then, is substantially perpendicular to the optical disc 108. The hologram 106a transmits the laser beam as it is. The quarter-wave plate 106b converts the polarization of the laser light, which was previously P-polarized light, into circularly polarized light. The objective lens 107 converts the laser light, which was substantially parallel light, into focused light so as to be focused on the recording surface of the optical disk 108. The laser light is incident on the optical disk 108 almost in focus.

  The laser light reflected by the recording surface of the optical disc 108 enters the beam splitter 103 through a route almost opposite to the forward path. At that time, the quarter-wave plate 106b converts the polarization of the laser light from circularly polarized light to S-polarized light. The hologram 106a separates the laser beam into light beams used for the RF signal, tracking error signal for tracking control, and focus error signal for focus control. The beam splitter 103 substantially totally reflects the incident laser light and makes it incident on the light receiving sensor 109. The light receiving sensor 109 outputs an RF signal, a tracking error signal, a focus error signal, and the like according to the amount of laser light incident on each light receiving element. The front light monitor 111 converts the incident laser light into an electric signal for output control of the laser light source 101.

An example of an optical system of an optical pickup using such a two-wavelength semiconductor laser is (Patent Document 1).
JP 2002-25103 A

  When a two-wavelength semiconductor laser light source is used as the laser light source, the distance between the light emitting point that emits the laser beam for DVD and the light emitting point that emits the laser beam for CD is short. Therefore, it is difficult to dispose the diffraction element only in the optical path of the laser beam for CD and to prevent the laser beam for DVD from being affected by the diffraction element. Conventionally, CD tracking control is performed using three beams, and DVD is performed using one beam. Therefore, in order to compensate for the loss caused by the side beam, the DVD laser light source must emit light with a larger output and make the amount of light of the main beam equal to that of the conventional one.

  On the other hand, DVDs are also required to be recorded at a high speed. For this purpose, the laser light source is required to emit light with a larger output. The fact that light is emitted with a large output means that the amount of heat generated by the laser light source is large. However, as the optical pickup becomes smaller and lighter, countermeasures are also difficult.

  SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned conventional problems, and to provide an optical pickup that does not increase the output of a DVD as compared with the conventional technique even when a two-wavelength semiconductor laser light source is used.

  In order to achieve the above object, an optical pickup of the present invention includes a laser light source provided with a light emitting point that emits laser light having a wavelength λ1 and a light emitting point that emits laser light having a wavelength λ2 (λ1 <λ2) close to each other; A hologram for separating the laser light of wavelength λ1 and the laser light of wavelength λ2 into a light beam for a one-beam method tracking control signal and a light beam for a focus control signal; and a light beam separated by the hologram And a light receiving sensor having a light detection surface for detecting each of them.

  A laser beam having a wavelength λ1 and a laser beam having a wavelength λ2 emitted from a two-wavelength semiconductor laser light source are separated into three beams by a diffraction grating, and a beam for a signal for tracking control of one beam method is generated by a hologram. Separated and incident on the light receiving sensor.

  The optical pickup according to the present invention separates the light beam for one-beam tracking control using a hologram for both the laser light having the wavelength λ1 and the laser light having the wavelength λ2 without entering a diffraction grating that separates the light into three beams, and enters the light receiving sensor. be able to. Therefore, both the laser light with the wavelength λ1 and the laser light with the wavelength λ2 can be used without wasting the output. Therefore, even if a two-wavelength semiconductor laser light source is used, it is not necessary to increase the light emission output, and high-speed recording, size reduction, and weight reduction can be achieved.

According to a first aspect of the present invention, there is provided a laser light source in which a light emitting point that emits laser light having a wavelength λ1 and a light emitting point that emits laser light having a wavelength λ2 (λ1 <λ2) are provided close to each other;
A hologram for separating the laser beam having the wavelength λ1 and the laser beam having the wavelength λ2 into a light beam for a signal for tracking control of one beam method and a light beam for a signal for focus control;
A light receiving sensor having a light detection surface for detecting each of the light beams separated by the hologram;
An optical pickup comprising:

  Without providing a diffraction grating that divides the beam into three beams, the laser beam having the wavelength λ1 and the laser beam having the wavelength λ2 can be separated into a light beam for tracking control of the one-beam method using a hologram and incident on the light receiving sensor. Therefore, both the laser light with the wavelength λ1 and the laser light with the wavelength λ2 can be used without wasting the output. Therefore, even if a two-wavelength semiconductor laser light source is used, it is not necessary to increase the light emission output, and high-speed recording, size reduction, and weight reduction can be achieved.

  According to a second invention, in the first invention, the light detection surface for detecting the laser light having the corresponding wavelength λ1 and the light detection surface for detecting the laser light having the wavelength λ2 are the same or electrically It is an optical pickup characterized by being connected to.

  The electrical output terminals corresponding to the laser beams having the wavelengths λ1 and λ2 are shared. Since no terminal is provided for each of the laser beams having the wavelengths λ1 and λ2, the number of terminals can be reduced, and the size of the light receiving sensor does not have to be increased.

  A third invention is the optical pickup according to the first invention, wherein the laser light source and the light receiving sensor are housed in one package.

  In addition to being able to reduce the size, it is easy to handle by integrating in advance.

  According to a fourth invention, in the first invention, a movable portion on which the objective lens and the hologram are mounted, a fixed portion that supports the movable portion with a support member, and a laser having wavelengths λ1 and λ2 on the surface by fixing the fixed portion. An optical pickup comprising an actuator including a yoke provided with light reflection preventing means.

  By providing the antireflection means, the generation of stray light can be suppressed, and the characteristics of recording and reproduction with respect to the optical disk are stabilized.

  A fifth invention is the optical pickup according to the fourth invention, wherein the antireflection means for the laser beam has a rough surface on the yoke.

  Stray light can be suppressed by irregularly reflecting the laser light. Further, reflection can be suppressed at low cost.

  A sixth invention is the optical pickup according to the fifth invention, wherein the rough surface is formed by acid treatment. There is less concern about adhesion of debris etc. than when mechanically roughened.

  A seventh invention is the optical pickup according to the fourth invention, wherein the antireflection means for the laser beam has a surface of the yoke substantially black. By absorbing the laser light, stray light can be suppressed.

  An eighth invention is the optical pickup according to the seventh invention, wherein the surface of the yoke is a black electroless nickel plating film. A stable black film is obtained. Moreover, the influence on a human body etc. is not large with respect to chromium plating or the like.

  A ninth invention is the optical pickup according to the fourth invention, wherein the surface of the yoke is subjected to an acid treatment and a black electroless nickel plating film is provided.

  By performing the acid treatment as a pretreatment for forming a black electroless nickel plating film, an antireflection means can be provided without increasing the cost.

  According to a tenth aspect of the present invention, in the fourth aspect of the invention, there is provided a light beam raising member that raises the laser light emitted from the laser light source so as to enter the objective lens. An optical pickup is provided on a surface of a yoke facing a back surface.

  The stray light is generated on the surface of the yoke facing the back surface of the light beam raising member, and the generation of stray light can be effectively suppressed by providing antireflection means there.

  An eleventh aspect of the invention is an optical disc apparatus comprising the optical pickup of the first aspect of the invention. The optical pickup can cope with high-speed recording, miniaturization, and weight reduction. Therefore, the optical disk device equipped with the optical pickup can also cope with high speed, miniaturization, and weight reduction.

(Embodiment 1)
The first embodiment will be described with reference to the drawings. FIG. 1 is a configuration diagram of the optical system of the optical pickup according to the first embodiment, and FIG. 2 is a configuration diagram of the optical pickup according to the first embodiment.

  The laser light source 1 includes a light emitting point 1a that emits laser light having a wavelength λ1 (about 650 nm) for DVD and a light emitting point 1b that emits laser light having a wavelength λ2 (about 780 nm) for CD. FIG. 3 is a configuration diagram of a main part of the laser light source unit according to the first embodiment. The laser light source 1 is disposed in a recess 8b formed on a substrate 8a constituting the light receiving sensor 8. The laser light source unit 10 includes a laser light source 1 and a light receiving sensor 8, and these are housed in one package. In the first embodiment, the laser light source 1 is a so-called monolithic two-wavelength semiconductor laser light source in which the light emitting point 1a and the light emitting point 1b are arranged close to each other in one light emitting element. However, a so-called hybrid two-wavelength semiconductor laser light source in which a light emitting element having a light emitting point 1a and a light emitting element having a light emitting point 1b are arranged adjacent to each other may be used. The laser beams emitted from the light emitting points 1a and 1b are respectively reflected by the inclined surface 8c toward the front side of the sheet of FIG. 3 and emitted from the laser light source unit 10.

  The substrate 8a of the light receiving sensor 8 to which the laser light source 1 is fixed is disposed on the heat radiating plate 10a, and the heat radiating plate 10a is further thermally connected to a heat radiating member (not shown). Therefore, the heat radiation property of the laser light source 1 is very excellent, and the temperature of the laser light source 1 itself is not easily raised even when the laser light source 1 is used at a high output. Supply of power to the laser light source 1 and output of various signals generated by the light receiving sensor 8 are performed through the FPC 10b. The cap 10 c covers the light receiving sensor 8 on which the laser light source 1 is disposed, and protects the laser light source 1 and the light receiving sensor 8. The cap 10c has a window (not shown). The cap 10c emits laser light emitted from the laser light source 1 through the window toward the optical disc 7, and reflects the laser light reflected by the optical disc 7 to the light receiving sensor 8. Or make it incident. The laser light source unit 10 is attached to the carriage 12 via a position adjustment member or a tilt adjustment member.

  The beam splitter 2 is formed by forming a polarization separation film on a surface of a substrate made of optical glass, optical plastic, or the like facing the laser light source 1. The polarization separation film is composed of a dielectric multilayer film or the like, and reflects most of the outgoing laser light emitted from the laser light source 1 to the optical disk 7 and transmits a part thereof to the front light monitor 9. . Further, the laser beam on the return path reflected by the optical disk 7 is almost totally reflected and directed to the light receiving sensor 8. The beam splitter 2 is attached to the carriage 12.

  The collimating lens 3 is made of optical glass or optical plastic. The collimating lens 3 converts the laser light, which is divergent light emitted from the laser light source 1, into substantially parallel light. The collimating lens 3 is attached to the carriage 12 directly or via an adjustment member so that the position adjustment in the optical axis direction can be performed.

  The rising mirror 4 as a light beam raising member is a mirror for raising an optical axis that has been in a plane substantially parallel to the surface of the optical disc 7 until then substantially perpendicular to the surface of the optical disc 7, and may be a prism. A total reflection film is formed on the surface of the rising mirror 4 facing the laser light source 1 and the optical disk 7. The total reflection film is a dielectric multilayer film or a metal film. The raising mirror 4 is fixed to the carriage 12.

  The hologram element 5 includes a hologram 5 a and a quarter wavelength plate 5 b and is fixed to a lens holder 14 between the rising mirror 4 and the objective lens 6. The hologram 5a has polarization selectivity, transmits the laser beam in the forward path as it is, and works as a hologram for the laser beam in the return path. The quarter-wave plate 5b is set to have a refractive index and a thickness so that it acts on both the laser light having the wavelength λ1 and the laser light having the wavelength λ2.

  The objective lens 6 is made of optical glass or optical plastic. The objective lens 6 converts substantially parallel laser light into focused light so as to be focused on the recording surface of the optical disk 7. The objective lens 6 uses a combination of a condensing lens and a Fresnel lens or a hologram lens, a combination of a condensing lens for DVD with an aperture limiting means during CD reproduction, and a lens that absorbs the difference in thickness and numerical aperture of the optical disc 7 is also used. can do. The objective lens 6 is fixed to a lens holder 14 that is a movable part of the actuator 13.

  The optical disk 7 is CD, CD-ROM, CD-R / RW, DVD system is DVD-ROM, DVD ± R / RW, DVD-RAM, etc. All can be recorded and played back.

  The light receiving sensor 8 has a plurality of light detection surfaces 8d on the substrate 8a, converts them into electrical signals corresponding to the amount of light incident on each light detection surface 8d, and outputs them to the outside through the FPC 10b. The light receiving sensor 8 is disposed in the laser light source unit 10 which is one package together with the laser light source 1.

  The front light monitor 9 is a sensor that receives light emitted from the light emitting points 1a and 1b of the laser light source 1 and transmitted through the beam splitter 2, converts the light amount into an electric signal, and outputs the signal. This electric signal is sent to a control circuit (not shown) that controls a drive circuit (not shown) of the laser light source 1 so that the amount of light of the condensed spot condensed on the optical disk 7 becomes constant. The front light monitor 9 is disposed on the carriage 12.

  The carriage 12 forms the skeleton of the optical pickup 11. As described above, the components constituting the optical pickup 11 including various optical components are attached to the carriage 12 directly or via other components. The carriage 12 is formed of an alloy material such as Zn alloy or Mg alloy, or a hard resin material.

  Next, the optical path will be described. The laser beam having the wavelength λ1 for DVD is emitted from the light emitting point 1a and is P-polarized light. Further, the laser light having the wavelength λ2 for CD is emitted from the light emitting point 1b and is P-polarized light. The outgoing laser beam toward the optical disk 7 is emitted from the laser light source 1 and immediately reflected by the inclined surface 8 c, passes through the window of the cap 10 c of the laser light source unit 10, and enters the beam splitter 2. The forward laser light that is P-polarized light is mostly reflected by the polarization separation film of the beam splitter 2 and partially transmitted. The reflected forward laser beam is converted into substantially parallel light by the collimator lens 3, the optical path is raised substantially perpendicular to the surface of the optical disk 7 by the rising mirror 4, and is incident on the hologram element 5. The P-polarized laser beam passes through the hologram 5a of the hologram element 5 as it is and enters the quarter-wave plate 5b. The forward laser beam of P-polarized light is converted into circularly polarized light by the quarter-wave plate 5 b and enters the objective lens 6. The forward laser beam is converted into focused light by the objective lens 6 and focused on the recording surface of the optical disc 7.

  The laser beam reflected by the recording surface of the optical disk 7 and converted into the return path light is converted into substantially parallel light by the objective lens 6 and enters the quarter wavelength plate 5 b of the hologram element 5. The circularly polarized backward laser beam is converted by the quarter-wave plate 5b into S-polarized light rotated by 90 ° from the forward path and is incident on the hologram 5a. The S-polarized return laser beam is separated by the hologram 5a into a light beam for a focus control signal and a light beam for a one-beam tracking control signal. The RF signal is generated using a part of the tracking control signal. The return path laser light separated by the hologram 5 a of the hologram element 5 is converted into a plane substantially parallel to the surface of the optical disk 7 by the rising mirror 4 and enters the collimating lens 3. The laser beam in the return path converted into the focused light that is substantially focused by the light receiving sensor 8 by the collimator lens 3 enters the beam splitter 2. The laser beam of the S-polarized return path is totally reflected by the polarization separation film of the beam splitter 2 and enters the light receiving sensor 8 of the laser light source unit 10. Each light beam separated by the hologram 5a enters the corresponding light detection surface 8d, is converted into an electric signal corresponding to the light amount, and is output.

Signals generated from each light detection surface 8d are as follows. A focus error signal FES for focus control of a DVD is assumed that the output of the corresponding light detection surface 8d is F11 and F12.
FES = F12-F11
It is calculated by the following relational expression. Further, the focus error signal FES for controlling the focus of the CD is assumed that the outputs of the corresponding light detection surface 8d are F21 and F22.
FES = F22-F21
It is calculated by the following relational expression.

  Here, F11 is obtained by electrically coupling a plurality of light detection surfaces 8d to obtain one output result. The same applies to F21, F12, and F22. The same applies to T15, T16, T25, and T26 described later.

  Further, it is desirable that F11 and F21 are further electrically coupled to obtain one output result. The same applies to F12 and F22. This has the effect of reducing the number of output terminals by sharing the DVD output terminal and the CD output terminal and preventing the light receiving sensor 8 from increasing in the vertical direction in FIG. This has the effect of not increasing the height of the optical pickup 11 and, as a result, does not hinder the thinning of the optical disk device.

  The same effect can be obtained by connecting the photodetection surface 8d that outputs F11 and F21 to the common photodetection surface 8d, and the photodetection surface 8d that outputs F12 and F22 is the same.

  In the first embodiment, the spot size method is adopted as the focus control. The light beam incident on one of the light detection surface 8d that outputs F11 and F21 and the light detection surface 8d that outputs F12 and F22 is focused before entering the light detection surface 8d, and the light beam incident on the other is the light detection surface. The hologram 5a was configured to focus after entering into 8d. However, the present invention is not limited to the spot size method, and focus control may be performed by the astigmatism method or the knife edge method.

  Using the same hologram 5a, the laser light having the wavelength λ1 for DVD and the laser light having the wavelength λ2 for CD are incident on the light receiving sensor 8 at different positions because the path is slightly different because the wavelength is different. It is.

The tracking error signal TES for DVD tracking control varies depending on the type of the optical disk 7 to be used. When the output of the corresponding light detection surface 8d is T1, T2, T3, T4, T15, T16, the tracking error signal TES of the DVD-ROM is
TES = ∠ (T1-T2) + ∠ (T4-T3)
It is calculated by the following relational expression. Here, ∠ is a voltage obtained by converting the phase difference of the output in parentheses. The tracking error signal TES of DVD ± R / RW is
TES = T15-T16
It is calculated by the following relational expression. The tracking error signal TES of DVD-RAM is
TES = (T2 + T3)-(T1 + T4)
It is calculated by the following relational expression.

Further, the tracking error signal TES for CD tracking control also differs depending on the type of the optical disk 7 to be used. When the output of the corresponding light detection surface 8d is T1, T2, T3, T4, T25, T26, the tracking error signal TES of the CD-ROM is
TES = ∠ (T1-T2) + ∠ (T4-T3)
It is calculated by the following relational expression. The tracking error signal TES of CD-R / RW is
TES = (T2 + T3)-(T1 + T4) -k (T25-T26)
It is calculated by the following relational expression. Here, k is a constant determined according to the operation setting.

  As in the case of focus control, it is desirable that T15 and T25 be electrically coupled to obtain one output result. The same applies to T16 and T26. This has the effect of reducing the number of output terminals by sharing the DVD output terminal and the CD output terminal and preventing the light receiving sensor 8 from increasing in the vertical direction in FIG. This has the effect of not increasing the height of the optical pickup 11 and, as a result, does not hinder the thinning of the optical disk device.

  The same effect can be obtained by connecting the photodetection surface 8d that outputs T15 and T25 to the common photodetection surface 8d, and the photodetection surface 8d that outputs T16 and T26 is the same.

  The tracking control is a one-beam method in which the tracking error signal TES is generated from one beam, and the hologram 5a is configured so that these signals can be generated. Using the same hologram 5a, the laser light having the wavelength λ1 for DVD and the laser light having the wavelength λ2 for DVD are different from each other as in the light detection surface 8d that outputs T15 and T25 and T16 and T26. This is because the path is slightly changed due to the difference in wavelength, which is the same as that for focus control. Further, the position where the laser light with wavelength λ1 and the laser light with wavelength λ2 are close to the light detection surface 8d that outputs T1, T2, T3, and T4 is different in the order of diffraction at the hologram 5a. This is because the way of influence is different.

Regardless of the type of optical disc 7 for both DVD and CD, the RF signal RF is
RF = T1 + T2 + T3 + T4
It is calculated by the following relational expression.

  The hologram 5a is configured such that a combination of a focus error signal FES for focus control, a tracking error signal TES for tracking control, and an RF signal RF is optimally generated.

  As described above, in the first embodiment, without providing a diffraction grating that separates the light into three beams, the laser beam having the wavelength λ1 and the laser beam having the wavelength λ2 is separated from the light beam for tracking control by the single beam method using the hologram 5a. 8 can be made incident. Therefore, both the laser light with the wavelength λ1 and the laser light with the wavelength λ2 can be used without wasting the output. Therefore, even if a two-wavelength semiconductor laser light source is used as the laser light source 1, it is not necessary to increase the light emission output, and high speed recording can be performed. Further, since a two-wavelength semiconductor laser light source can be used, the size and weight can be reduced.

  By the way, in the first embodiment, it is desirable to electrically couple the light detection surfaces 8d that output F11 and F21, F12 and F22, T15 and T25, and T16 and T26, or to share the light detection surface 8d. did. This was for the purpose of reducing the number of output terminals by sharing the output terminal for DVD and the output terminal for CD in order to reduce the thickness of the optical pickup 11. Therefore, for example, even when recording or reproduction is performed on the optical disk 7 of a CD, not only the photodetection surface 8d for CD but also the photodetection surface 8d for DVD unnecessary for CD recording and reproduction always operate. Will be. Therefore, when unnecessary light such as stray light is incident on the photodetecting surface 8d for DVD, the CD focus control signal and tracking control signal are affected, and the recording and reproduction operations become unstable. It is possible. The same applies to DVD recording and playback.

  Therefore, the optical pickup 11 of the first embodiment is further provided with the following configuration. That is, antireflection means for laser light having wavelengths λ1 and λ2 is provided on the surface of the yoke 15 of the actuator 13.

  FIG. 4 is a configuration diagram of the actuator according to the first embodiment, and FIG. 5 is a configuration diagram of the yoke according to the first embodiment. The lens holder 14 which is a movable part includes n through holes 14a and 14b. The objective lens 6 is fixed from the upper surface side of the through hole 14a. The hologram element 5 is fixed from the lower surface side of the through hole 14a. A focus coil 19 and a tracking coil 20 are attached inside the through hole 14b. As will be described later, the lens holder 14 is formed of a liquid crystal polymer containing a glass filler, which is an insulating material, in order to hold and electrically insulate and hold the suspension wire 16 which is a support member. Further, the surface of the objective lens 6 has a substantially black surface so that stray light is less likely to be generated.

  Three suspension wires 16 are provided on each side of the lens holder 14. The end of the suspension wire 16 is electrically connected to the focus coil 19 and the tracking coil 20. The suspension wire 16 is composed of an elastic conductive material, and is composed of a linear body or a flat body such as an iron alloy or a copper alloy (for example, a copper-beryllium alloy).

  The suspension holder 17 which is a fixed part is made of an insulating material, and the other end of the suspension wire 16 is embedded. That is, the suspension holder 17 elastically cantileverally supports the lens holder 14 via the suspension wire 16 as a support member so as to be displaceable. The suspension holder 17 is provided with a circuit board (not shown) attached or close thereto, and the circuit board and the suspension wire 16 are electrically connected.

  The suspension holder 17 is mounted on a yoke 15 made of a magnetic material such as an iron alloy. The yoke 15 is provided with a front end yoke portion 15a, side standing portions 15b, 15c, 15d and 15e, and standing yoke portions 15f and 15g which are bent on the same side. The front end yoke portion 15a and the standing yoke portions 15f and 15g are provided to face each other. Moreover, magnets 18a, 18b, and 18c are attached to the surfaces of the front end yoke portion 15a on the upright yoke portions 15f and 15g side and the surfaces of the upright yoke portions 15f and 15g on the front end yoke portion 15a side. At this time, the front end yoke portion 15a, the standing yoke portions 15f and 15g, and the magnets 18a, 18b, and 18c are fixed by an ultraviolet curable adhesive, a thermosetting adhesive, or the like.

  The focus coil 19 and the tracking coil 20 are disposed inside the through hole 14b by winding a coated conductive wire made of copper or a copper alloy in a cylindrical shape. The focus coil 19 is disposed so that the standing yoke portions 15f and 15g to which the magnets 18b and 18c are attached penetrate through the inner sides of the respective cylindrical shapes. The tracking coil 20 is disposed between the magnet 18a and the magnets 18b and 18c.

  The actuator 13 has a configuration in which a suspension holder 17 fixed to a yoke 15 supports the lens holder 14 with a suspension wire 16. The actuator 13 is fixed to the carriage 12 with side standing portions 15b, 15c, 15d, and 15e by an ultraviolet curable adhesive or a thermosetting adhesive.

  FIG. 6A is a top surface arrangement diagram of the optical component centering on the objective lens according to the first embodiment, and FIG. 6B is an AA cross-sectional view thereof. The laser light emitted from the laser light source 1 enters the optical disc 7 through a path indicated by a one-dot chain line in FIG. At this time, for example, if not all of the laser light transmitted through the collimating lens 3 is reflected by the rising mirror 4 but only a part of the laser light reaches the front end yoke portion 15a of the yoke 15 of the actuator 13, the laser light that has reached it. Can be stray light. Here, when the laser beam reaches the front end yoke portion 15a, it passes through the outside of the rising mirror 4 and directly reaches the front end yoke portion 15a. May reach the front end yoke portion 15a.

  When the laser light reaches the front end yoke portion 15a, the front end yoke portion 15a is very close to the objective lens 6 and the hologram element 5 and affects focus control and tracking control as stray light. Therefore, it is desirable to provide an antireflection means for the laser beam on the yoke 15, particularly on the surface of the front end yoke portion 15 a of the yoke 15 facing the back surface of the rising mirror 4.

  In the first embodiment, the surface of the yoke 15 is roughened by acid treatment, and a black electroless nickel plating film is formed thereon. First, the yoke 15 is finished into a predetermined shape with a press or the like. Next, a plating pretreatment is performed. First, organic stains such as oil are removed by washing with a detergent and washed with pure water. Next, alkaline degreasing is performed and pure water is washed. Further, it is immersed in 10-20% hydrochloric acid for 10-30 seconds and washed with water. By immersing in hydrochloric acid, the surface of the yoke 15 made of an iron alloy or the like becomes rough.

  Next, plating is performed. A predetermined electroless nickel-phosphorous plating film is formed in an electroless plating bath using sodium hypophosphite as a reducing agent. Finally, it is immersed in an acidic treatment solution containing cupric chloride, nickel chloride, and hydrochloric acid to form a nickel phosphate compound on the surface, thereby blackening the surface of the plating film. The optimal pretreatment liquid and conditions, electroless nickel plating bath and plating conditions, acidic treatment liquid and treatment conditions are appropriately selected.

  The surface of the yoke 15 subjected to the above treatment is a rough black surface. Therefore, even if laser light is incident on such a surface, most of the surface is absorbed, and even if only a part of the surface is reflected, it is irregularly reflected. By performing the above processing, the stray light incident on the light detection unit 8d can be reduced to about 1/5. As a result, much of the influence of stray light in focus control and tracking control can be eliminated, and focus control and tracking control can be performed more stably.

  In Embodiment 1, acid treatment was performed as a pre-plating process to roughen the surface, and after forming an electroless nickel plating film, the film was blackened by immersion in an acidic treatment solution. Therefore, it was possible to make the process almost the same as the formation of a normal electroless nickel plating film. However, it is not limited to that. Surface roughening and blackening may be carried out independently. For example, a smooth surface can be obtained by immersing the acid treatment liquid in the previous step in 5 to 10% sulfuric acid. The surface may be blackened by forming an electroless nickel plating film. On the contrary, it is not necessary to roughen the surface in the previous step and to form black after forming the electroless nickel plating film. In that case, although the effect as an antireflection means of a laser beam is small, manufacturing cost can be reduced.

  For blackening, another black plating film may be formed. For example, there are black chrome plating, black nickel plating, chromate and the like. However, for black chrome plating and chromate, it is necessary to give due consideration to the environment, and for black nickel plating, it is necessary to consider that the corrosion resistance and black color are somewhat thin. Moreover, you may perform blackening by coating. At that time, the entire yoke 15 may be painted, or only the surface of the front end yoke portion 15a facing the objective lens 6 may be painted. Alternatively, the portion corresponding to the surface of the front end yoke portion 15a facing the objective lens 6 in the state of the plate before being processed into the shape of the yoke 15 may be painted, and then processed into the shape of the yoke 15.

(Embodiment 2)
The second embodiment will be described with reference to the drawings. FIG. 7 is a configuration diagram of the optical pickup module according to the second embodiment, and FIG. 8 is a configuration diagram of the optical disk device according to the second embodiment. The second embodiment is an optical disk device on which the optical pickup described in the first embodiment is mounted.

  A drive mechanism that drives the optical disk 7 and the optical pickup 11 of the optical disk device 50 is referred to as an optical pickup module 30. The base 31 forms a framework of the optical pickup module 30, and each component is fixed directly or indirectly to the base 31.

  A spindle motor 32 having a turntable on which the optical disk 7 is placed is fixed to the base 31. The spindle motor 32 generates a rotational driving force that rotates the optical disc 7.

  The feed motor 33 is fixed to the base 31. The feed motor 33 generates a rotational driving force necessary for the optical pickup 11 to move between the inner periphery and the outer periphery of the optical disc 7. A stepping motor, a DC motor, or the like is used as the feed motor 33. The screw shaft 34 is formed with a spiral groove, and is connected to the feed motor 33 directly or via several stages of gears. In the second embodiment, it is directly connected to the feed motor 33. The guide shafts 35 and 36 are fixed to the base 31 via support members 38 at both ends. The guide shafts 35 and 36 support the optical pickup 11 so as to be movable. The optical pickup 11 fixes a rack 37 having guide teeth that mesh with the grooves of the screw shaft 34. The optical pickup 11 can move between the inner periphery and the outer periphery of the optical disc 7 in order for the rack 37 to convert the rotational driving force of the feed motor 33 transmitted to the screw shaft 34 into a linear driving force.

  The optical pickup 11 is provided with an FPC cover 22 and an actuator cover 23 as described in the first embodiment. The optical pickup 11 performs at least one of recording and reproduction of information on the optical disc 7 and emits laser light toward the optical disc 7 for that purpose. The inclination of the guide shafts 35 and 36 is adjusted by an adjustment mechanism that constitutes the support member 38 so that the laser light emitted from the optical pickup 11 is incident on the optical disk 7 at a right angle.

  The upper casing 51a and the lower casing 51b are combined and fixed to each other using screws or the like to form the casing 51. The tray 52 is provided in the casing 51 so as to be able to appear and disappear. In the tray 52, the optical pickup module 30 to which the cover 39 is attached is arranged from the lower surface side. The cover 39 has an opening to expose a part including the objective lens 6 of the optical pickup 11 and the turntable of the spindle motor 32. In the case of the second embodiment, the feed motor 33 is also exposed. A bezel 53 is provided on the front end surface of the tray 52 so that when the tray 52 is stored in the housing 51, the entrance and exit of the tray 52 is closed.

  The bezel 53 is provided with an eject switch 54, and when the eject switch 54 is pressed, the engagement between the housing 51 and the tray 52 is released, and the tray 52 can be brought into and out of the housing 51. The rails 55 are slidably attached to both sides of the tray 52 and the casing 51, respectively.

  There is a circuit board (not shown) inside the casing 51 and inside the tray 52, and a signal processing system IC, a power supply circuit, and the like are mounted. The external connector 56 is connected to a power / signal line provided in an electronic device such as a computer. Then, power is supplied into the optical disc device 50 via the external connector 56, an electric signal from the outside is guided into the optical disc device 50, or an electric signal generated by the optical disc device 50 is supplied to an external electronic device or the like. Or send it out.

  As described above, the optical disc apparatus 50 according to the second embodiment includes the optical pickup 11 described in the first embodiment. The optical pickup 11 of the first embodiment can use the laser light having the wavelength λ1 and the laser light having the wavelength λ2 without wasting the output. Therefore, even if a two-wavelength semiconductor laser light source is used, it is not necessary to increase the light emission output, and high-speed recording, size reduction, and weight reduction can be achieved. In addition, focus control and tracking control can be performed more stably. Therefore, the optical disk device 50 of the second embodiment can be reduced in size and weight, can realize high-speed recording, and can perform focus control and tracking control more stably.

  As described above, the optical pickup of the present invention is mounted on an optical disk device mounted on a notebook PC that is desired to be reduced in size and weight. The optical disk apparatus of the present invention is preferably mounted on a notebook PC.

Configuration diagram of the optical system of the optical pickup of the first embodiment Configuration diagram of optical pickup of Embodiment 1 Configuration diagram of main part of laser light source unit of Embodiment 1 Configuration diagram of actuator of Embodiment 1 Configuration diagram of yoke according to the first embodiment (A) Top view arrangement of optical components centering on the objective lens of the first embodiment, (b) AA sectional view thereof Configuration diagram of optical pickup module of Embodiment 2 Configuration diagram of optical disc apparatus of Embodiment 2 Configuration diagram of optical system of conventional optical pickup

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Laser light source 1a, 1b Light emission point 2 Beam splitter 3 Collimating lens 4 Raising mirror 5 Hologram element 5a Hologram 5b 1/4 wavelength plate 6 Objective lens 7 Optical disk 8 Light receiving sensor 8a Substrate 8b Concave 8c Inclined surface 8d Light detection surface 9 Front light Monitor 10 Laser light source unit 10a Heat sink 10b FPC
10c Cap 11 Optical pickup 12 Carriage 13 Actuator 14 Lens holder 15 Yoke 16 Suspension wire 17 Suspension holder 18a, 18b, 18c Magnet 19 Focus coil 20 Tracking coil 21 FPC
22 FPC cover 23 Actuator cover 30 Optical pickup module 31 Base 32 Spindle motor 33 Feed motor 34 Screw shaft 35, 36 Guide shaft 37 Rack 38 Support member 39 Cover 50 Optical disk device 51 Housing 51a Upper housing 51b Lower housing 52 Tray 53 Bezel 54 Eject switch 55 Rail 56 External connector

Claims (11)

A laser light source in which a light emitting point that emits laser light having a wavelength λ1 and a light emitting point that emits laser light having a wavelength λ2 (λ1 <λ2) are provided close to each other
A hologram for separating the laser light of wavelength λ1 and the laser light of wavelength λ2 into a light beam for a signal for one-beam tracking control and a light beam for a signal for focus control;
A light receiving sensor having a light detection surface for detecting each of the light beams separated by the hologram;
An optical pickup characterized by comprising: Each of the corresponding light detection surfaces for detecting the laser light with the wavelength λ1 and the light detection surface for detecting the laser light with the wavelength λ2 are the same or electrically connected. The optical pickup according to claim 1. The optical pickup according to claim 1, wherein the laser light source and the light receiving sensor are housed in one package. A movable part for mounting the objective lens and the hologram, a fixed part for supporting the movable part with a support member, and a means for fixing the fixed part and preventing reflection of the laser beams having the wavelengths λ1 and λ2 on the surface are provided. The optical pickup according to claim 1, further comprising an actuator including a yoke. The optical pickup according to claim 4, wherein the laser beam antireflection means has a rough surface of the yoke. The optical pickup according to claim 5, wherein the rough surface is formed by acid treatment. 5. The optical pickup according to claim 4, wherein the antireflection means of the laser beam has a surface of the yoke that is substantially black. 8. The optical pickup according to claim 7, wherein the surface of the yoke is a black electroless nickel plating film. The optical pickup according to claim 4, wherein the surface of the yoke is subjected to an acid treatment and a black electroless nickel plating film is provided. A surface of the yoke having a light beam raising member that raises the laser light emitted from the laser light source to be incident on the objective lens, wherein the laser beam antireflection means faces the back surface of the light beam raising member; The optical pickup according to claim 4, wherein the optical pickup is provided. An optical disc apparatus comprising the optical pickup according to claim 1.

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