JP2009087462A - Objective lens driving device, optical pickup device, and optical disk device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an objective lens driving device which can be miniaturized and thinned capable of preventing unnecessary distortion caused by adhesion by facilitating the positioning of an optical element in a lens holder while securing the rigidity of the movable part of the objective lens driving device. <P>SOLUTION: A roughly square recess 37 is formed at a lens holder 28 to fix an optical element 36, the flat plate optical element 36 where four square corners a are chamfered is positioned with respect to the recess, and roughly equal amounts of adhesives are dropped into adhesive dropping parts 38 formed among the chamfered parts of the optical element 36 present at the four corners of the recess, thereby securing the rigidity of the lens holder 28, and facilitating positioning. Thus, the unnecessary distortion of the optical element 36 caused by adhesion is prevented. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an objective lens driving device that drives an objective lens for recording or reproducing information by focusing laser light on an information recording surface of an optical disc, a pickup device including the objective lens, and an optical disc device including the objective lens driving device.

  2. Description of the Related Art In recent years, optical disc apparatuses that use an optical disc as an information recording medium and record information such as audio signals and video signals with high density and reproduce the same have become widespread. In such an optical disk device, an optical pickup device is used to focus a laser beam on the information recording surface of the optical disk to form a light spot and receive reflected light from the information recording surface.

  The above optical disk device is mounted on a notebook computer or the like, and with the downsizing and thinning of the optical disk device, there is a strong demand for downsizing and thinning of each component part mounted in the optical disk device. There is a strong demand for thinning an optical pickup device.

  In the optical pickup device, a light spot is formed on an optical disk by an objective lens, and the position of the light spot is controlled by moving the objective lens with high accuracy by an objective lens driving device. The objective lens driving device performs focusing by controlling the objective lens in the optical axis direction, and performs tracking by controlling in the direction orthogonal to the optical axis (radial direction of the optical disk). In some cases, tilt control about the radial tilt axis is performed by controlling the tilt of the objective lens in accordance with the tilt of the information recording surface of the optical disc with respect to the optical axis.

  As the recording / reproducing speed increases, the rotational speed of the optical disk increases, and it is necessary to follow the optical disk rotating at high speed, and the servo control system is required to have high responsiveness. That is, a wide frequency band is required for the servo system. Therefore, in the optical disk device, in addition to increasing the thrust of the objective lens driving device, it is necessary to increase the higher order resonance frequency of the movable part of the objective driving device, and in particular, the structural rigidity of the movable part is required.

  In many cases, in addition to the objective lens, an optical element such as a diffraction grating or a liquid crystal element is disposed in the movable portion including the objective lens of the objective driving device. Since the optical element needs to be operated integrally with the objective lens while maintaining a predetermined positional relationship, it is mounted on the movable part, but it is a major component of the movable part in order to provide a space for placing the optical element. There is a problem that a part where the thickness of a part of a lens holder is reduced occurs, and the rigidity of the lens holder is reduced.

In Patent Document 1, the lens holder is divided into an objective lens installation part and an optical element installation part, and assembled while adjusting the position, thereby assembling the objective lens and the optical element in a predetermined positional relationship and the thickness of the optical element installation part. It is described that the rigidity of the lens holder is increased by forming a thickness.
JP 2004-152447 A

  In response to demands for miniaturization and thinning of information recording / reproducing devices, when the objective lens driving device is pursued to be lightweight and thin, the rigidity of components such as a lens holder constituting the objective lens driving device tends to decrease. This works against the higher order resonance of the servo control system. For this reason, it is also important to take measures to ensure the rigidity of the parts of the movable part while realizing a light weight and a thin shape.

  When mounting an optical element on a lens holder having an objective lens at the center of the upper surface facing the optical disk and having a hollow substantially rectangular parallelepiped shape, and having a coil mounting portion on both sides of the objective lens, the lens holder Since there are many parts where the thickness of the central part of the lens becomes thinner, it is difficult to ensure the rigidity of the lens holder.

  In addition, the optical element is fixed to the lens holder by bonding. However, if the bonding location is uneven, an uneven external force acts on the optical element due to thermal expansion or wet expansion of the adhesive, and optical May cause distortion. Therefore, it is necessary to bond the optical element evenly so that unnecessary external force does not act in accordance with the shape of the optical element.

  The present invention has been made in view of the above circumstances, and is capable of reducing the size and thickness of the objective lens driving device while ensuring the rigidity of the movable portion of the objective lens driving device, and the optical pickup device and optical disc device incorporating the objective lens driving device. The purpose is to provide.

  In order to achieve the above object, an objective lens driving device according to the present invention includes an objective lens for condensing laser light on an information recording surface of an optical disc, and a hollow substantially rectangular parallelepiped shape at the center of an upper surface facing the optical disc. A movable part having the objective lens and having a lens holder provided with a coil attachment part on both sides of the objective lens as a center, and joined to the coil attachment part, respectively, and the movable part is driven to translate in the focus direction. Two sets of coils that combine a focus coil and a tracking coil that translates in the tracking direction, two sets of magnets that are respectively disposed on opposite sides of the two sets of coils across the lens holder, A fixed part to which two sets of magnets are fixed, one end is fixed to the fixed part, the other end is fixed to the lens holder, and the lens holder is made hollow A support member for holding the lens, and the lens holder has a flat plate-like optical element having four corners chamfered on the opposite side of the optical disk of the objective lens and faces the objective lens. It is characterized by having a position.

  The optical pickup device of the present invention includes a light source that emits laser light and an objective lens driving device, and the objective lens driving device includes an objective lens that focuses the laser light on an information recording surface of an optical disc; A movable portion having a lens holder having a hollow substantially rectangular parallelepiped shape and having the objective lens at a central portion of an upper surface facing the optical disc, the coil holder being provided on both sides of the objective lens; Two sets of coils, each of which is joined to each of the two parts, and which combines a focus coil that translates the movable part in the focus direction and a tracking coil that translates the movable part in the tracking direction, and both sides of the two sets of coils across the lens holder. Two sets of magnets respectively disposed at opposing positions, a fixed portion to which the two sets of magnets are fixed, and one end fixed to the fixed portion And a support member that holds the lens holder in a hollow state. The lens holder includes a plate-like optical element having four corners chamfered in the shape of the objective. The lens is provided at a position opposite to the optical disk and facing the objective lens.

  The optical disc apparatus according to the present invention includes an optical pickup device including an objective lens driving device, a drive control unit that controls driving of the objective lens driving device, and a signal processing that processes a signal output from the optical pickup device. And an objective lens that condenses the laser light on the information recording surface of the optical disc. The objective lens driving device includes a laser control unit that modulates recording data and outputs the laser control signal as a laser control signal to the optical pickup device. A movable portion having a lens holder having a hollow substantially rectangular parallelepiped shape and having the objective lens at a center portion of an upper surface facing the optical disc, and having a coil mounting portion on both sides of the objective lens as a center; Each of the movable parts is joined to the coil mounting part, and the movable part is translationally driven in the focus direction and the tracking coil is translationally driven. Two sets of coils combined with a racking coil, two sets of magnets disposed at opposite positions on both sides of the two sets of coils with the lens holder in between, and a fixed to which the two sets of magnets are fixed And a support member that has one end fixed to the fixing portion, the other end fixed to the lens holder, and holds the lens holder in a hollow state, and the four corner portions of the lens holder are chamfered. A flat plate-shaped optical element having the above-described shape is provided on the opposite side of the objective lens from the optical disc and at a position facing the objective lens.

  According to the present invention, while ensuring the rigidity of the movable part of the objective lens driving device, the optical element can be easily positioned on the lens holder, and unnecessary distortion due to adhesion can be prevented. An objective lens driving device, an optical pickup device incorporating the objective lens driving device, and an optical disk device can be provided.

  Hereinafter, an embodiment of an objective lens driving device, an optical pickup device, and an optical disk device according to the present invention will be described with reference to the drawings.

  FIG. 1 is a block diagram showing the overall configuration of an optical disc apparatus 1 including an optical pickup device 2 of the present invention. In FIG. 1, an optical pickup device 2 includes an objective lens 3 and an objective lens driving device 4 that is a driving device for the objective lens 3, and faces an information recording surface of an optical disk 5. The optical disk 5 is rotationally driven by a disk motor 6. The disk motor 6 is controlled by a disk motor control circuit 7. Information recording / reproduction with respect to the optical disc 5 is performed by the optical pickup device 2. The optical pickup device 2 is driven in the radial direction of the optical disk 5 by a thread motor 8 and is supported so as to be movable in the direction of arrows AB. The thread motor 8 is controlled by a thread motor control circuit 9.

  The objective lens 3 of the optical pickup device 2 is moved in the focusing direction (the optical axis direction of the objective lens 3) and the tracking direction (the direction orthogonal to the optical axis of the objective lens 3, the radial direction of the optical disk) by the objective lens driving device 4. Movement is controlled, and tilt control is further performed.

  Information is written on the optical disk 5 by irradiating the optical disk 5 with a laser beam emitted from the semiconductor laser 10 as a light source via the beam splitter 11. Reading (reading) of information from the optical disk 5 is performed on the optical disk 5. The reflected light from 5 is guided to the photoelectric converter 12 through the objective lens 3 and the beam splitter 11.

  The semiconductor laser 10 is driven and controlled by the laser control circuit 13, and the laser light modulated in accordance with the recording information is condensed on the information recording surface of the optical disk 5 via the beam splitter 11 and the objective lens 3, and is applied to the optical disk 5. Record information.

  The laser light reflected by the optical disk 5 travels backward through the objective lens 3, is bent by the beam splitter 11, and enters the photoelectric converter 12. The photoelectric converter 12 includes a photodetector, converts the detected light into an electrical signal, and supplies the signal to the signal processing circuit 14. The signal processing circuit 14 outputs a signal for data reproduction based on the output signal of the photoelectric converter 12, and outputs a signal for focus control and a signal for tracking control.

  The focus control signal is supplied to the objective lens driving device 4 via the focus control circuit 15. The tracking control signal is supplied to the objective lens driving device 4 via the tracking control circuit 16. Further, a tilt control circuit 17 is provided to control the tilt of the light emitted from the light spot with respect to the tilt of the optical disc 5, and a tilt correction signal is supplied to the objective lens driving device 4. The objective lens driving device 4 is driven and controlled by the focus control circuit 15, tracking control circuit 16 and tilt control circuit 17. If tilt control is not required, the tilt control circuit may be omitted.

  The objective lens 3 is subjected to focus control, tracking control and tilt control by the objective lens driving device 4, and each coil (described later) for controlling the focus, tracking and tilt of the objective lens 3 is provided. The flexible printed wiring board 18 is connected to the printed wiring board 19.

  The semiconductor laser 10 is also connected to the printed wiring board 19 via the laser flexible printed wiring board 20, and the photoelectric converter 12 is electrically and mechanically connected to the printed wiring board 19. Thereby, the optical pickup device 2 is electrically connected to the outside through the printed wiring board 19, and controls the semiconductor laser 10, the objective lens driving device 4, and the signal generated by the photoelectric converter 12. Can be performed. The controller 21 includes a CPU (Central Processing Unit), controls the transmission / reception of information with each unit and the operation of each unit via the bus 22, and comprehensively controls the optical disc apparatus 1.

  Next, the configuration of the objective lens driving device 4 that is the driving device for the objective lens 3 will be described with reference to FIGS. 2, 3, and 4. FIG. 2 is a perspective view showing the external appearance of the objective lens driving device 4, and FIG. 3 is a perspective view showing the movable portion 23 of the objective lens driving device 4. FIG. 4 is a perspective view of the movable part 23 of the objective lens driving device 4 as seen from the back side. In the movable portion 23, the objective lens 3 is disposed, and the surface facing the optical disc 5 is the front side.

  In FIG. 2, the fixed portion 24 that supports the movable portion 23 includes a yoke base 25, a wire holder body portion 26 a that is disposed on the rear side of the yoke base 25 and has a substantially rectangular parallelepiped shape, and a wire holder that is fixed to the further rear side of the wire holder body portion 26 a. It is constituted by a fixed plate 26b.

  The yoke base 25 is a metal base, and one end of the yoke base 25 is fixed to the wire holder 26. The wire holder 26 integrally includes a wire holder main body portion 26a and a wire holder fixing plate 26b for attaching one end portion of the support wire 27. The wire holder main body portion 26a has one end of a plurality of (for example, six) support wires 27. It is attached. The support wire 27 is a support member that is formed in a rod shape with a conductive material having elasticity, extends in parallel three by three, and supports the lens holder 28 at its distal end. 2, the X direction indicates the tracking direction, the Z direction indicates the focus direction, and the Y direction indicates a direction orthogonal to the X direction and orthogonal to the Z direction. The support wire is disposed along the Y-axis direction.

  One end portion of each support wire 27 penetrates the wire holder 26 and is electrically connected to the wire holder fixing plate 26 b and further electrically connected to the flexible printed wiring board 18. The other end portion of the flexible printed wiring board 18 is connected to the printed wiring board 19. The other end portions of the plurality of support wires 27 are fixed and electrically connected to the connector portion 29 shown in FIG. 3, and further connected to a coil (described later) in the lens holder 28.

  The lens holder 28 has a lens attachment portion 28d for attaching the objective lens 3 at the center thereof, and has coil attachment portions 28a and 28b so as to sandwich the objective lens 3. The lens holder 28 is movably supported by the support wire 27, and focuses the objective lens 3 with respect to the fixed portion 24 in the focus direction (lens axis direction: Z-axis direction in the figure) and the tracking direction that is the radial direction of the optical disk 5. It is possible to shift in the (X-axis direction). Further, it is supported so that tilt control in the rotational direction around the radial tilt axis (around the axis parallel to the Y axis) is possible. If tilt control is not required, tilt control around the radial tilt axis may be omitted.

  As shown in FIG. 3, coils 30a and 30b are installed in the coil attachment portions 28a and 28b, respectively. The coil 30a is a combination of four coils: a focus coil 31a, tracking coils 32a1, 32a2, and a tilt coil 33a. Similarly, the coil 30b is a combination of four coils: a focus coil 31b, tracking coils 32b1, 32b2, and a tilt coil 33b. The focus coils 31a and 31b are a pair, the tracking coils 32a and 32b are a pair, and the tilt coils 33a and 33b are a pair. The coils 30a and 30b are attached to both sides in the X-axis direction with the objective lens 3 as the center. The tilt coils 33a and 33b are disposed so as to overlap the focus coils 31a and 31b, respectively. If tilt control is not necessary, the tilt coil may be omitted.

  On the other hand, as shown in FIG. 2, the yoke base 25 has two sets of magnets (shown by broken lines) 34a, 35a and 34b, 35b used for driving the objective lens 3 in the focus direction, tracking direction and tilt direction. Are disposed at opposite positions on both sides of the two sets of coils with the lens holder interposed therebetween. A focus coil 31a, tracking coils 32a1, 32a2, and a tilt coil 33a are located between the magnets 34a, 35a, and a focus coil 31b, tracking coils 32b1, 32b2, and a tilt coil 33b are located between the magnets 34b, 35b. ing.

  In the following description, the focus coils 31a and 31b are collectively referred to as the focus coil 31, the tracking coils 32a and 32b are collectively referred to as the tracking coil 32, and the tilt coils 33a and 33b are collectively referred to as the tilt coil 33. . The magnets 34a and 34b are generically called a magnet 34, and the magnets 35a and 35b are generically called a magnet 35.

  The magnets 34 and 35 form a magnetic field, and a part of the focus coil 31 and the tracking coil 32 is exposed to the magnetic field, and controls the magnitude and direction of the current flowing through the focus coil 31 and the tracking coil 32. Thus, the lens holder 28 (objective lens 3) can be shifted in the focus direction and the tracking direction. Further, the objective lens 3 can be tilt-controlled by controlling the magnitude and direction of the current flowing through the tilt coil 33, respectively.

  The lens holder 28 thus supported by the support wire 27 and the focus coil 31, tracking coil 32, tilt coil 33 and the like attached thereto constitute the movable part 23 together with the objective lens 3.

  One end of the metal yoke base 25 is fixed to the wire holder 26, and the other end has a U-shaped yoke 25a. Magnets 34 and 35 are fixed to the inside of the yoke 25a facing each other. Yokes 25c and 25d erected from the yoke base 25 are provided between the magnets 34a and 35a and between the magnets 34b and 35b.

  As shown in FIG. 4, an optical element 36 is installed on the back side of the lens holder 28. The optical element 36 includes, for example, a ¼ wavelength plate, a dichroic filter, a hologram element, a liquid crystal element, and the like, which are properly used according to a required function. The optical element 36 shown in FIG. 4 has a flat plate shape, the outer shape is substantially square, and the corners of four corners of the square are chamfered. It is provided at a position opposite to the front side surface and facing the objective lens 6. As shown in FIG. 4, when the four corners of the quadrangle are chamfered and the chamfer is large, the shape is substantially octagonal.

  On the back side of the lens holder 28, a concave portion 37 is provided for positioning the optical element 36 and fixing the optical element 36 by adhesion. The concave portion 37 has a substantially rectangular shape and is formed with a size slightly larger than the optical element 36. The depth may be determined appropriately according to the amount of adhesive used later. Regarding the positioning of the optical element 36 in the X and Y directions with respect to the lens holder 28, the side walls 36a and 36b of the optical element 36 are positioned by being pressed against the side walls 37a and 37b of the recess 37, respectively. There are many optical elements whose orientation in the XY plane is determined at the time of installation. Many of them are positioned with a predetermined accuracy with respect to the center of the objective lens (substantially optical center).

  A space formed between the chamfered portions of the optical element 36 present at the four corners of the concave portion 37 is an adhesive dripping portion 38. The optical element 36 is bonded and fixed to the lens holder 28, but it is desirable that the adhesive is bonded as symmetrically as possible with respect to the outer shape forming the side surface of the optical element 36. In the case where the bonded portions are uneven, an uneven external force acts on the optical element due to thermal expansion or wet expansion of the adhesive, which may cause optical distortion. Therefore, it is necessary to bond the optical element 36 evenly so that unnecessary external force does not act in accordance with the shape of the optical element. By dropping the same amount of adhesive into the spaces of substantially the same shape formed at the four corners, the four corners of the optical element 36 are similarly bonded and fixed.

  Next, the shape of the optical element is compared between the case where the four corners of the square are not chamfered and the case where the corner is chamfered, and the advantages of the chamfer will be described with reference to FIGS. 5 and 6. FIGS. 5A and 5B are schematic views showing examples of another shape of the concave portion of the lens holder and the optical element. This is a case where the four corners of the quadrangle of the optical element are not chamfered. FIG. 5A shows a state where no optical element is installed, and FIG. 5B shows a state where an optical element is installed. A concave portion 42 for positioning the optical element 41 is provided at the center of the lens holder 40. Adhesive dripping portions 43 are provided at the four corners of the recess 42. The optical element 41 has a quadrangular outer shape and no chamfering at the four corners. The lens holder 40 is provided with window holes 46 for passing the focusing coil 44 and the yoke 45 on both sides of the optical element 41. A magnet 47 is disposed opposite the lens holder 40.

  As shown in FIG. 5B, the adhesive is evenly applied to the optical element 41 by dropping the adhesive onto the hatched portion. However, when the shape of the concave portion 42 is such, the distance L1 between the adhesive dripping portion 43 and the window hole 46 is reduced, and the portion where the thickness of the lens holder 40 is reduced is increased. The rigidity of 40 will be reduced.

  6A and 6B are schematic views showing examples of the shape of the concave portion of the lens holder and the optical element in the present invention. The case where four corners of the quadrangle of the optical element are chamfered is shown. FIG. 5 is a schematic diagram illustrating an example of the same shape as the concave portion 37 and the optical element 36 illustrated in FIG. 4. The focusing coil 44, yoke 45, window hole 46, and magnet 47 are the same as those in FIG. The concave portion 52 of the lens holder 50 is substantially square, and the distance between opposite sides is slightly larger than that of the optical element 51. The optical element 51 has a substantially octagonal shape by chamfering four corners of a quadrangle. As shown in FIG. 6B, the adhesive is evenly applied to the optical element 51 by dropping the adhesive onto the adhesive dropping portion 53 indicated by hatching.

  The distance L2 between the recess 52 and the window hole 54 is determined by the size of the optical element 51. However, since the portion where the thickness of the lens holder becomes thin is suppressed to a minimum, the lens holder is compared with FIG. 50 rigidity can be secured.

  FIG. 7 is a diagram showing an example of another shape of the optical element. The four corners of the optical element 60 may be chamfered in an arc shape, or the four elements of the circular optical element may be chamfered in parallel and at equal intervals, so that the optical element 51 shown in FIG. Has the same effect.

  As described above, according to the present invention, when the optical element 36 is disposed in the movable portion 23 of the objective lens driving unit 4, the substantially square recess 37 for fixing the optical element 36 to the lens holder 28 is provided. An adhesive formed between the chamfered portions of the optical element 36 located at the four corners of the concave portion 37 by positioning the flat plate-shaped optical element 36 having four corners of the quadrangular chamfered with respect to the concave portion 37. By dropping substantially the same amount of adhesive on the dropping portion 38, the rigidity of the lens holder can be ensured, positioning can be facilitated, and unnecessary distortion due to adhesion of the optical element can be prevented.

1 is a block diagram showing an optical disc apparatus of the present invention. The perspective view which shows the external appearance of an objective lens drive device. The perspective view which shows the movable part of an objective lens drive device. The perspective view which looked at the movable part of the objective lens drive device from the back side. The schematic diagram which shows the example of another shape of the recessed part of a lens holder, and an optical element. The schematic diagram which shows the example of the shape of the recessed part of a lens holder in this invention, and an optical element. The figure which shows the example of another shape of an optical element.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical disk apparatus 2 Optical pick-up apparatus 3 Objective lens 4 Objective lens drive apparatus 5 Optical disk 10 Semiconductor laser 11 Beam splitter 12 Photoelectric converter 13 Laser control circuit 14 Signal processing circuit 15 Focus control circuit 16 Tracking control circuit 17 Tilt control circuit 18 Flexible printing Wiring board 19 Printed wiring board 20 Flexible printed wiring board for laser 21 Controller 23 Movable part 24 Fixed part 25 Yoke base 26 Wire holder 26a Wire holder main body part 26b Wire holder fixing plate 27 Support wire 28 Lens holder 29 Connector board 30a, b Coil 31a, b Focus coil 32a1, a2, b1, b2 Tracking coil 33a, b Tilt coil 34a, b Magnet 35a, b Magnet 36 Optical element 37 Recess 38 Adhesive dropping part 0 lens holder 41 the optical element 42 recess 43 adhesive dropping unit 44 coil 45 yoke 46 window opening 47 magnet 50 lens holder 51 the optical element 52 recess 53 adhesive dropping unit 60 the optical element

Claims (9)

An objective lens that focuses the laser beam on the information recording surface of the optical disc;
A movable portion having a hollow substantially rectangular parallelepiped shape and having the objective lens at the center of the upper surface facing the optical disc, and having a lens holder with coil attachment portions on both sides of the objective lens as a center;
Two sets of coils, each of which is joined to the coil mounting portion and combines a focus coil that translates the movable portion in a focus direction and a tracking coil that translates in a tracking direction;
Two sets of magnets respectively disposed at opposite positions on both sides of the two sets of coils across the lens holder;
A fixing portion to which the two sets of magnets are fixed;
One end is fixed to the fixing part, the other end is fixed to the lens holder, and the support member that holds the lens holder in a hollow state,
The lens holder includes a flat plate-shaped optical element having four corners of a square chamfered at a position opposite to the optical disk of the objective lens and facing the objective lens. An objective lens driving device.   The objective lens driving device according to claim 1, wherein the optical element is substantially octagonal.   The objective lens driving device according to claim 1, wherein the lens holder has a substantially quadrangular concave portion for positioning and bonding and fixing the optical element. A light source that emits laser light;
An objective lens driving device,
The objective lens driving device includes an objective lens for condensing laser light on an information recording surface of an optical disc, and the objective lens in a central portion of an upper surface that has a substantially hollow rectangular parallelepiped shape and faces the optical disc, and the objective lens A movable part having a lens holder provided with a coil attachment part on both sides thereof, and a focus coil that is joined to the coil attachment part to drive the movable part in translation in the focus direction and tracking that translates in the tracking direction. Two sets of coils in which the coils are combined, two sets of magnets disposed on opposite sides of the two sets of coils across the lens holder, and a fixed portion to which the two sets of magnets are fixed And one end fixed to the fixing portion, the other end fixed to the lens holder, and a support member for holding the lens holder in a hollow state, The sensor holder is provided with a flat plate-shaped optical element having four corners chamfered at a position opposite to the optical disk of the objective lens and facing the objective lens. Optical pickup device.   The optical pickup device according to claim 4, wherein the optical element is substantially octagonal.   6. The optical pickup device according to claim 4, wherein the lens holder has a substantially rectangular recess for positioning and fixing the optical element. An optical pickup device including an objective lens driving device;
A drive control unit for controlling the drive of the objective lens driving device;
A signal processing unit for processing a signal output from the optical pickup device;
A laser control unit that modulates recording data and outputs the modulated data as a laser control signal to the optical pickup device;
The objective lens driving device includes an objective lens for condensing laser light on an information recording surface of an optical disc, and the objective lens in a central portion of an upper surface that has a substantially hollow rectangular parallelepiped shape and faces the optical disc, and the objective lens A movable part having a lens holder provided with a coil attachment part on both sides thereof, and a focus coil that is joined to the coil attachment part to drive the movable part in translation in the focus direction and tracking that translates in the tracking direction. Two sets of coils in which the coils are combined, two sets of magnets disposed on opposite sides of the two sets of coils across the lens holder, and a fixed portion to which the two sets of magnets are fixed And one end fixed to the fixing portion, the other end fixed to the lens holder, and a support member for holding the lens holder in a hollow state, The sensor holder is provided with a flat plate-shaped optical element having four corners chamfered at a position opposite to the optical disk of the objective lens and facing the objective lens. Optical disk device.   8. The optical disc apparatus according to claim 7, wherein the optical element is substantially octagonal.   9. The optical disk apparatus according to claim 7, wherein the lens holder has a substantially square-shaped recess for positioning and fixing the optical element.

Images