JP2009032316A - Pickup device and recording medium playback device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pickup device having a plurality of objective lenses and capable of employing firm structure while keeping a good weight balance, and a recording medium playback device including such a pickup device. <P>SOLUTION: The pickup device 10 is equipped with the first lens 11 for receiving a light from a recording medium, the second lens 12 for receiving the light from the recording medium, a lens holder 15 for holding the first and second lenses, the first and second driving member holding parts 16 and 17 disposed roughly on both sides of the lens holder, respectively, driving members 71 to 76 for driving the lens holder and disposed in the first and second driving member holding parts, respectively and a reinforcing member 50 for interconnecting the first and second driving member holding parts. The recording medium playback device 1 including such a pickup device is also provided. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a pickup device and a recording medium playback device.

  In a reproducing apparatus for an optical disk, in order to move a lens holding unit that holds one objective lens in a tracking direction and a focusing direction so as to follow a predetermined track surface of a recording medium, in order to achieve a balance at that time It is known to arrange a balance weight in the lens holding part (for example, Patent Documents 1 and 2).

  Further, it is known that a metal center of gravity adjustment member for balancing a lens holding portion that holds one objective lens is disposed in the vicinity of the drive coil and used as a heat sink for the drive coil (for example, Patent Document 3).

JP-A-61-210529 (FIG. 1) Japanese Patent Laid-Open No. 3-154235 (FIG. 2) Japanese Patent Laid-Open No. 2001-23202 (FIG. 1)

  In recent years, a recording medium playback device such as an optical disc must support many standards such as CD, DVD, BD (Blue-ray Disc), HD-DVD (High Definition Digital Versatile Disc), MD, and so on. There may be a case where a lens movable portion on which a plurality of objective lenses are mounted. These objective lenses do not necessarily have the same material and the same size in order to correspond to the transmittance and NA (aperture ratio) of the light beam used. That is, there has been a problem that weight imbalance occurs between the objective lenses.

  The actuator for driving a plurality of objective lenses arranged close to the optical disk side is naturally arranged on both sides of the objective lens. However, as the recording density of the recording medium increases, the NA is increased. Therefore, it is necessary to dispose the objective lens closer to the recording medium such as an optical disk. Then, the position of the center of gravity of the lens movable portion moves toward the objective lens, and there is a problem that when the lens movable portion is moved in the tracking direction, the balance is lost and it is difficult to control the movement.

Therefore, an object of the present invention is to provide a pickup device and a recording medium reproducing device that can solve the above-described problems.
Another object of the present invention is to provide a pickup device that can make the pickup device itself a robust structure while maintaining a good weight balance, and a recording medium reproducing device having such a pickup device.

Furthermore, the present invention provides a recording medium reproducing apparatus capable of preventing the reproduction signal from being deteriorated due to the occurrence of coma aberration due to the lens tilt generated during driving due to the deviation (unbalance) between the center of the movable part and the driving center. The purpose is to do.
Furthermore, the present invention avoids an overlap between the lens driving unit and the head optical path corresponding to a thin head, and therefore it is possible to prevent the structure of the optical head from becoming weak and the structural resonance frequency from being lowered. An object is to provide a playback device.
Furthermore, the present invention provides a recording medium capable of preventing the burning of a coil that generates heat and the deterioration of performance in order to obtain DC focus offset driving and high acceleration (motion performance) to cope with a plurality of recording media. An object is to provide a playback device.

  A pickup device according to the present invention includes a first lens that receives light from a recording medium, a second lens that receives light from the recording medium, a lens holder that holds the first and second lenses, and substantially both sides of the lens holder. The first and second driving member holding portions, the driving member for driving the lens holder provided in the first and second driving member holding portions, and the first and second driving member holding portions are connected to each other. It has the reinforcing member to do.

  The recording medium reproducing apparatus according to the present invention includes a first lens that receives light from the recording medium, a second lens that receives light from the recording medium, a lens holder that holds the first and second lenses, and a lens. First and second driving member holding portions disposed on substantially both sides of the holder, a driving member for driving a lens holder provided in the first and second driving member holding portions, and first and second driving members It has a pickup device having a reinforcing member for connecting the holding portion, and a moving means for moving the pickup device.

  According to the pickup device and the recording medium reproducing device according to the present invention, the side portions disposed on both sides having a drive unit for driving the plurality of objective lenses, which are substantially in the middle of the plurality of objective lenses. Since the reinforcing member is arranged so as to be connected, the center of gravity shifted to the lens side can be set to the center of the pickup device, and the movement control of the pickup device can be performed smoothly.

  Further, according to the pickup device and the recording medium reproducing device according to the present invention, since the reinforcing member can balance the weight between the plurality of lenses, the center of gravity shifted due to the weight difference between the plurality of objective lenses can be obtained. The center of the lens movable portion can be set at the center, and the movement of the pickup device can be controlled smoothly.

  Furthermore, according to the pickup device and the recording medium reproducing device according to the present invention, when the reinforcing member is formed of a metal material, it can function as a heat radiating plate of the drive coil of the objective lens.

  Furthermore, according to the pickup device and the recording medium reproducing device according to the present invention, the reinforcing member is disposed so as to connect between the side portions disposed on both sides having the driving unit for driving the plurality of objective lenses. Therefore, it became possible to connect the drive coil between the side parts arrange | positioned on both sides efficiently using a reinforcement member.

  Hereinafter, a pickup apparatus and a recording medium reproducing apparatus according to the present invention will be described with reference to the drawings. However, it should be noted that the technical scope of the present invention is not limited to these embodiments, but extends to the invention described in the claims and equivalents thereof.

  FIG. 1 is a diagram showing a relationship between a recording medium and an optical head, and FIG. 2 is a schematic cross-sectional view along AA ′ in FIG.

  The recording medium reproducing apparatus 1 reproduces (and / or records) optical information from a recording medium 2 such as a CD, DVD, BD (Blue-ray Disc), HD-DVD (High Definition Digital Versatile Disc), MD, or the like. An optical head 3 having various elements, a lead screw (feed screw) 4 as a main shaft for moving the optical head 3 along the radial direction B of the recording medium 2 by a drive motor 6, and a guide 7 as a sub shaft are provided. is doing.

  As shown in FIG. 1, the optical head (pickup) 3 reproduces information from a guide portion 5 for engaging with the lead screw 4, an engaging portion 8 for engaging with the guide 7, and a CD and a DVD. The first objective lens 11, the second objective lens 12 for reproducing information from the recording medium 2 for BD (or HD-DVD), and the like.

  As shown in FIG. 2, the optical head 3 includes a pickup device 10 that holds the first objective lens 11, the second objective lens 12, and the like, a support portion 20 that movably supports the pickup device 10 with a support wire, An optical system for BD, an optical system for DVD and CD, and the like are arranged.

  The first objective lens 11 is a plastic lens having an aperture ratio (for example, NA = 0.60) and a focal length (for example, 0.6 mm) for reproducing CD and DVD recording media, and the second objective lens 12 is: A glass lens having an aperture ratio (for example, NA = 0.85) and a focal length (for example, 0.1 mm) for reproducing a BD recording medium.

  In the optical head 3, the light beam (wavelength 650 nm) emitted from the first laser diode 40 for DVD and CD is converted into parallel light by the first collimator lens 41 after passing through the first beam splitter 42. The optical path is bent by about 90 degrees by the rising mirror 44, enters the first objective lens 11, and is focused on the track surface of the DVD or CD recording medium by the first objective lens 11. The collected light beam is reflected on the track surface of the recording medium for DVD or CD, and again passes through the first objective lens 11, the first rising mirror 44, and the first collimating lens 41 to the first beam splitter 42. Incident. The light beam incident on the first beam splitter 42 is condensed on the first photodetector 43 with the optical path bent by about 90 degrees.

  The first photodetector 43 drives the pickup device 10 based on the incident beam to appropriately move the first objective lens 11, and a DVD and CD recording medium. The playback signal from is output.

  In the optical head 3, the light beam (wavelength 405 nm) emitted from the second laser diode 45 for BD passes through the second beam splitter 47 and is converted into parallel light by the second collimating lens 46. The optical path is bent about 90 degrees by the rising mirror 49 and is incident on the second objective lens 12, and is condensed on the track surface of the recording medium for BD by the second objective lens 12. The condensed light beam is reflected on the track surface of the BD recording medium, and is incident on the second beam splitter 47 again via the second objective lens 12, the second rising mirror 49, and the second collimating lens 46. . The light beam incident on the second beam splitter 47 is condensed on the second photodetector 48 by bending the optical path by about 90 degrees.

  Based on the incident beam, the second photodetector 48 drives the lens movable unit 10 to appropriately move the second objective lens 12 and a second focus error signal and a second tracking error signal from the BD recording medium. The playback signal is output.

  FIG. 3 is a diagram illustrating a schematic configuration of the pickup device.

  The pickup device 10 further includes a first tracking coil 71, a second tracking coil 72, a third tracking coil 73, a first tracking coil 74, a first focusing coil 75, and a second focusing function that function as a driving member. A coil 76 for use. The pickup device 10 includes a lens holder 15 that holds the first objective lens 11 and the second objective lens 12, a first tracking coil 71, a second tracking coil 72, and a first focusing coil 75, and A first side portion 16 that functions as a driving member holding portion, a third tracking coil 73, a fourth tracking coil 74, and a second focusing coil 76 that are disposed and function as a driving member holding portion; It is comprised from the reinforcement member 50 etc. which connect the 1st side part 16 and the 2nd side part 17. FIG.

  The pickup device 10 including the lens holder unit 15 has a first support wire 60, a second support wire 61, a third support wire 62, and a fourth support wire 63 with respect to the fixing member 20 disposed in the optical head 3. It is elastically supported so that it can move.

  Further, as shown in FIG. 3, the optical head 3 is provided with a magnet yoke 29 integrally formed of a first back yoke 21, a second back yoke 22, a first center yoke 27 and a second center yoke 28. It has been. The first back yoke 21 is provided with a first magnet 23 and a fourth magnet 26, and the second back yoke 22 is fixed with a second magnet 24 and a third magnet 25. In FIG. 3, for convenience of explanation, the fixing member 20 is separated from the optical head 3, but actually, it is joined to the magnet yoke 29 and fixed on the optical head 3.

  Accordingly, the first center yoke 27 is inserted into the opening provided in the first side portion 16 of the pickup device 10, and the second center yoke 28 is inserted into the opening provided in the second side portion 17, so that the first The tracking coil 71 and the first magnet 23 face each other, the second tracking coil 72 and the second magnet 24 face each other, the third tracking coil 73 and the third magnet 25 face each other, and the fourth tracking coil 74 and the like. The pickup device 10 is supported by the support wires 60 to 63 so that the fourth magnet 26 is opposed.

  The pickup device 10 can move in the arrow C (tracking direction) by the interaction between the tracking coils 71 to 74 and the magnetic circuit composed of the magnet yoke 29 and the magnets 23 to 26. Further, the pickup device 10 is movable in the arrow D (focusing direction) by the interaction between the focusing coils 75 and 76 and the magnetic circuit composed of the magnet yoke 29 and the magnets 23 to 26. In addition, a predetermined space is provided between the openings of the first side portion 16 and the second side portion 17 and the first and second guide members 27 and 28, and the pickup device is within the range allowed by the space. 10 is controlled to move in the tracking direction C and the focusing direction D to follow a predetermined position on the track surface of the recording medium. The tracking direction C is arranged so as to coincide with the radial direction B of the recording medium 2.

  FIG. 4 is a diagram showing a schematic configuration of the photodetector.

  As shown in FIG. 4, the first photodetector 43 includes six detection elements A to F, and each detection element is configured to generate a voltage corresponding to the amount of received light. In the case where the first objective lens 11 favorably focuses the light spot on a predetermined track of the recording medium, the light is reflected from the recording medium 2 to the photodetector at the center of the four detection elements A to D. The center of the spot of the returned light beam coincides. When the position of the light spot by the first objective lens 11 shifts, the position of the light spot condensed on the six detection elements A to F is also shifted from the center accordingly.

  Therefore, the first amplifier 80 amplifies the voltage of (A + C)-(B + D) and outputs a focus error signal (FE signal), and the second amplifier 81 amplifies the voltage of (E−F) for tracking. An error signal (TE signal) is output. A control unit (not shown) (including a CPU, a ROM, a RAM, and the like) drives the tracking coils 71 to 76 and the focusing coils 75 to 76 in accordance with the FE signal and the TE signal, whereby the first objective lens 11. It becomes possible to always follow the position of the light spot focused by a predetermined track on the recording medium 2.

  Since the output of the FE signal and TE signal from the second photodetector 48 and the driving of the second objective lens 12 are the same as described above, the description thereof is omitted.

  Fig.5 (a) is a figure which shows the state before attaching a reinforcement member, FIG.5 (b) is a figure which shows the state after mounting | wearing with a reinforcement member.

  The reinforcing member 50 is disposed at a substantially intermediate position between the first objective lens 11 and the second objective lens 12. Therefore, when the pickup device 10 is supported by the fixing member 20, the reinforcing member 50 is arranged in the space between the first rising mirror 44 and the second rising mirror 49 (see FIG. 2). . Because of such an arrangement relationship, even when the pickup device 10 is appropriately moved in the tracking direction C and the focusing direction D, the first rising mirror 44, the second rising mirror 49, the reinforcing member 50, Will not interfere. Further, because of such an arrangement relationship, the pickup device 10 can be arranged close to the first rising mirror 44 and the second rising mirror 49, and the height of the optical head 3 can be kept low. There is.

  As the recording density of the recording medium increases, an objective lens having a large NA is used. Therefore, the objective lens needs to be arranged closer to the recording medium such as an optical disk. That is, the lens holding part 15 is arranged on the recording medium 2 side, and the first side part 16 and the second side part 17 are arranged on both sides thereof. As a result, with such a structure, the center of gravity of the entire pickup device is shifted to the objective lens side. On the other hand, since the reinforcing member 50 is disposed so as to connect the first side portion 16 and the second side portion 17 at a substantially intermediate position between the first objective lens 11 and the second objective lens 12. The center of gravity of the entire pickup device 10 can be moved further downward in the drawing in the focusing direction D, that is, to the center of the pickup device 10.

  The reinforcing member 50 includes a first terminal portion 51 and a second terminal portion 52, and the first terminal portion 51 and the second terminal portion 52 are disposed so as to protrude toward the first objective lens 11 side. . This is because the first objective lens 11 is a plastic lens, the second objective lens 12 is a glass lens, and there is a weight difference, so that the center of gravity of the entire pickup device 10 is shifted to the second lens 12 side. This is to compensate. That is, the first terminal portion 51 and the second terminal portion 52 of the reinforcing member 50 function as a weight balancer so that the center of gravity of the entire pickup device 10 can be arranged at the center of the lens movable portion 10. . Since the pickup apparatus 10 must be instantaneously moved in the tracking direction C and the focusing direction D, movement control may be difficult if the center of gravity is not located at the center. Therefore, the reinforcing member 50 functions as a weight balancer of the pickup device 10 and thereby has an effect of enabling the movement control of the pickup device 10 to be performed more smoothly. Note that the shapes of the terminal portions 51 and 52 shown in the figure are examples, and other shapes can be adopted as long as the weight difference between the first objective lens 11 and the second objective lens 12 can be compensated. is there.

  Further, the reinforcing member 50 is formed of aluminum, the first terminal portion 51 is disposed in proximity to the first focusing coil 75, and the second terminal portion 52 is disposed in proximity to the second focusing coil 76. Has been. Therefore, the reinforcing member 50 functions as a heat dissipation material when the first focusing coil 75 and the second focusing coil 76 generate heat. In particular, since the pickup device 10 needs to be offset-driven to the respective focus positions of various recording media, and particularly the focusing coil tends to heat, the reinforcing member 50 is used to heat such a focusing coil. This has the effect that it can be prevented. The reinforcing member 50 may be formed of a metal material other than aluminum, such as copper or tungsten, as long as it has good heat conduction or heat dissipation.

  Further, the reinforcing member 50 is disposed so as to connect the first side portion 16 and the second side portion 17. For example, in the case of the pickup device 10 ′ not provided with the reinforcing member as shown in FIG. 6A, the structure unique to the structure in the direction of the arrow E on the first side portion 16 ′ and the second side portion 17 ′ by movement. The fluttering mode due to the resonance mode is generated at a low frequency due to its weak structure, and there is a possibility that abnormal noise or movement control abnormality occurs. Therefore, as shown in FIG. 6B, the first side portion 16 and the second side portion 17 are connected by the reinforcing member 50 to strengthen the structure against the force in the direction of the arrow E. As a result, resonance and movement control abnormality can be prevented.

  Further, the reinforcing member 50 has a groove portion 53, and the groove portion 53 functions as a wiring place of a connection line for connecting the coil on the first side portion 16 side and the coil on the second side portion 17 side. .

  As shown in FIG. 7A, the fourth support wire 63, the second focusing coil 76, the first connection line 80, the first focusing coil 75, and the first support wire 60 are connected in this order. A wiring path for focusing movement control is formed. The first connection line 80 that connects the first focusing coil 75 and the second focusing coil 76 is wired along the groove 53 of the reinforcing member 50.

  As shown in FIG. 7B, the third support wire 62, the third tracking coil 73, the fourth tracking coil 74, the second connection line 81, the first tracking coil 71, the second tracking coil 72, And the 2nd support wire 61 is connected in that order, and the wiring path | route for tracking movement control is formed. The second connection line 81 that connects the second tracking coil 72 and the third tracking coil 73 is wired along the groove 53 of the reinforcing member 50.

  If the first and second connection lines are arranged in the vicinity of the first and second objective lenses, there is a problem that the wiring route becomes long and the wiring labor increases, leading to an increase in cost. Therefore, the reinforcing member 50 has an effect that the above-described problems can be solved.

It is a figure which shows the relationship between a recording medium and an optical head. It is AA 'schematic sectional drawing in FIG. It is a figure which shows schematic structure of a pick-up. It is a figure which shows schematic structure of a photodetector. It is a figure (1) for demonstrating a reinforcement member. It is a figure (2) for demonstrating a reinforcement member. It is a figure which shows the wiring path | route of a coil.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Recording medium reproducing | regenerating apparatus 3 Optical head 10 Pickup apparatus 11 1st objective lens 12 2nd objective lens 15 Lens holder part 16 1st side part 17 2nd side part 20 Fixing part 50 Reinforcement member 51 1st terminal part 52 2nd terminal Part 53 Groove part 71, 72, 73, 74 Coil for tracking 75, 76 Coil for focusing

Claims (10)

A first lens for receiving light from a recording medium;
A second lens for receiving light from the recording medium;
A lens holder for holding the first and second lenses;
First and second drive member holding portions respectively disposed on substantially both sides of the lens holder;
A driving member for driving the lens holder provided in the first and second driving member holding parts;
A reinforcing member connecting the first and second driving member holding portions;
A pickup device comprising:   The pickup device according to claim 1, wherein the reinforcing member corrects a weight difference between the first lens and the second lens.   The reinforcing member corrects a difference between the weight of the first lens and the weight of the second lens, and arranges the center of gravity of the lens movable portion at a substantially central portion of the first and second lenses. The pickup device described in 1. The drive member is a drive coil;
The pickup device according to claim 1, wherein the reinforcing member radiates heat generated by the drive coil. The drive member is a drive coil;
The reinforcing member is made of a metal material,
The pickup device according to any one of claims 1 to 3, wherein an end portion of the reinforcing member is disposed in proximity to the drive coil. The drive member has a first drive coil provided in the first drive member holding part and a second drive coil provided in the second drive member holding part,
The pickup device according to claim 1, wherein the first drive coil and the second drive coil are connected by a connection line disposed on the reinforcing member. The driving member includes a first focusing driving coil and a first tracking driving coil provided in the first driving member holding part, and a second focusing driving coil and a second tracking provided in the second driving member holding part. Drive coil,
The first focusing drive coil and the second focusing drive coil are connected by a first connection line disposed on the reinforcing member, and the first tracking drive coil and the second tracking drive coil are connected to the reinforcing member. The pick-up apparatus as described in any one of Claims 1-5 connected by the 2nd connection line arrange | positioned at. A first lens that receives light from the recording medium, a second lens that receives light from the recording medium, a lens holder that holds the first and second lenses, and first lenses disposed on substantially both sides of the lens holder. A first and second driving member holding portion; a driving member for driving the holder provided in the first and second driving member holding portion; and a reinforcing member for connecting the first and second driving member holding portions. A pickup device having
Moving means for moving the pickup device;
A recording medium reproducing apparatus comprising: The pickup device further includes a first rising mirror for guiding light received by the first lens, and a second rising mirror for guiding light received by the second lens,
The recording medium reproducing apparatus according to claim 8, wherein the reinforcing member is disposed between the first and second rising mirrors. The pickup device further includes a support wire for elastically supporting the lens holder,
The drive member has a first drive coil provided in the first drive member holding part and a second drive coil provided in the second drive member holding part,
The recording medium reproducing device according to claim 8, wherein the first drive coil and the second drive coil are connected to the support wire via a connection line disposed on the reinforcing member.

Images