KR100189933B1 - Compatible optical pickup - Google Patents

Abstract

There is disclosed a disk compatible optical pickup device in which disc-shaped recording media having different formats can be compatible.

The optical pickup apparatus includes a light source, a beam splitter for changing the traveling path of the incident light, an objective lens disposed between the light source and the disk for focusing the incident light onto the disk, an actuator on which the objective lens is mounted, And a photodetector for detecting information and an error signal, wherein the objective lens comprises a first objective lens arranged at a predetermined distance from the actuator and having different numerical apertures, ; And a second objective lens, wherein the actuator includes a base on which a light source, a beam splitter, and a photodetector are located; A bobbin on which an objective lens is fixed, the bobbin being positioned on a base; A suspension which is once fixed on the base and movably supports the bobbin; And a magnetic drive means for driving the bobbin in the disc track radial direction and in the disc focus direction, wherein the beam splitter is provided so that light emitted from the light source is selectively transportable to the first objective lens and the second objective lens .

Description

Compatible optical pickup device

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a compatible optical pickup apparatus, and more particularly to a disc-compatible optical pickup apparatus compatible with disc-shaped recording media of different formats.

2. Description of the Related Art In general, an optical pick-up apparatus is an apparatus for recording and / or reproducing information on a disc in a non-contact manner while moving in a radial direction of a disc as a recording medium.

Digital video disk players (DVDPs) and DVD-ROMs are attracting attention in the field of video / acoustics as devices capable of high density recording / reproduction. The optical pickup device employed in this DVDP should be able to record / reproduce information even in the case of adopting a CD as well as a DVD as a recording medium for compatibility.

On the other hand, the thickness of the DVD has been standardized to be different from the CD thickness due to the mechanical disc tilt tolerance and the numerical aperture of the objective lens. That is, the thickness of the conventional CD is 1.2 mm, while the DVD is 0.6 mm. As described above, when the optical pickup apparatus for DVD is applied to CD with the thicknesses of CD and DVD being different from each other, spherical aberration due to thickness difference is generated. This spherical aberration causes a problem that a sufficient light intensity necessary for recording an information signal is not obtained or a signal at the time of reproduction deteriorates.

FIG. 1 shows a conventional compatible optical pick-up apparatus which has been considered in consideration of these points. The objective lens 19, the beam splitter 15, the hologram element 17, and the photodetector 23 in its constitution.

The light source 11 generates and emits laser light by a semiconductor laser. The objective lens 19 converges the incident light so that a light spot is formed on the recording surface of the optical disc 10. The beam splitter 15 is located on the optical path between the light source 11 and the objective lens 19 to prevent the light reflected from the optical disk from re-entering the light source 11. That is, most of the light 1 incident on the light source 11 passes straight through the beam splitter 15, and the light incident on the objective lens 19 is reflected to the photodetector 23 . The hologram element 17 is located on the optical path between the objective lens 19 and the beam splitter 15. The hologram element 17 separates the incident light 1 into a zero-order light beam 3 and a + first-order light beam 5 and outputs it. The zero-order light (3) is substantially straight with respect to the incident light, and the + first-order light (5) diverges. Therefore, the zero-order light beam (3) and the + first-order light beam (5) pass through different positions of the objective lens (19) and form foci at different positions. The zero-order light (3) is used for DVD, and the + first-order light (5) is used for CD. The photodetector 23 receives the light reflected from the recording surface of the optical disc 10 and detects an RF information signal, a track error signal and a focus error signal.

The photodetector 23 is composed of a plurality of dividing plates for independently receiving light. The photodetector 23 sums and differential-amplifies the signals received by the respective dividing plates to detect an RF information signal, a track error signal and a focus error signal do.

The optical pickup apparatus further includes a grating (13) and a collimating lens (15). The grating 13 is positioned between the light source 11 and the beam splitter, and diffracts the incident beam into a 0-order diffraction beam, a ± 1-order diffraction beam and the like. The collimating lens 16 is provided between the beam splitter 15 and the hologram element 17 and converts the incident light into parallel light. Further, an astigmatic lens 21 is provided between the beam splitter 15 and the photodetector 23. This astigmatism lens 21 has a generally semi-cylindrical shape. When the distance between the objective lens 19 and the optical disk 10 is on-focus, circular light is allowed to converge on the optical disk. So that light from the optical disc is formed on the optical disc.

This optical pickup apparatus separates the light emitted from the light source 11 into the 0-order light 3 and the +1-order light 5 in the hologram element 17. The separated light beams 3 and 5 converge while passing through the objective lens 19, and are converged on the optical disc. When the DVD 10a is adopted as the optical disc 10, information is recorded / reproduced by using the zero-order light 3 and when the CD 10b is adopted as the optical disc, / RTI >

Since the optical pickup apparatus thus provided selectively uses the 0-order light beam 3 and the + 1-order light beam 5 diffracted by the hologram element 17, the light efficiency of the light spot formed on the optical disk drops to within about 50%. Since the light passes through the hologram element 17 and is directed to the photodetector 23, the light received by the photodetector 23 is within about 25% of the light emitted from the light source 11 Light efficiency.

In addition, the conventional optical pickup apparatus includes the actuator 30 as shown in Fig. This actuator includes a base 31, a holder 32 fixed to the base 31, a bobbin 34 for fixing the objective lens 19, and a bobbin 34 connected to the holder 32 And a magnetic driving means for moving the bobbin 34 in the track direction or the focus direction. The magnetic driving means includes a focusing coil 35 wound on the outside of the bobbin 34, a tracking coil 36 attached to the focusing coil 35, a pair of magnets 38a and 38b, A pair of outer yokes 39a and 39b provided on the base 31 and fixing the magnets 38a and 38b respectively and a pair of outer yokes 39a and 39b fixed to the base 31 and fixed to the focus coil 35 and the bobbin And a pair of inner yokes 37a and 37b that are positioned between the bobbins 34 and guide the movement of the bobbins 34. [ Here, the tracking coil 36 is attached to the focus coil 35 so as to face each of the magnets 38a and 38b.

In the conventional actuator thus constructed, the focus coil 35 and the tracking coil 36 are wound around the bobbin 34 and the bobbin 34 and the focus coil 35 The inner yokes 37a and 37b are provided between the inner yokes 37a and 37b. Further, since the mass of the coil is large, the load for transferring the optical pickup device in the radial direction of the disk is large.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a compatible optical pickup device in which the optical efficiency is improved and the actuator is miniaturized by adopting a pattern coil integrated with the bobbin.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a configuration diagram showing an optical arrangement of a conventional compatible optical pickup device. FIG.

2 is a schematic perspective view showing a conventional actuator for an optical pickup.

3 is a configuration diagram showing an optical arrangement of a compatible optical pickup device according to an embodiment of the present invention.

4 is a configuration diagram showing an optical arrangement of a compatible optical pickup device according to another embodiment of the present invention.

5 is a schematic plan view of an actuator for an optical pickup according to an embodiment of the present invention.

6 is a partially enlarged view of Fig.

7 is a schematic diagram illustrating a first pattern coil according to the present invention.

8 is a schematic view showing a second pattern coil according to the present invention.

9 is a schematic view showing a connection part according to the present invention.

DESCRIPTION OF THE REFERENCE NUMERALS

10 ... disk 41 ... light source 42 ... collimating lens

43, 53 ... beam splitter 44 ... first objective lens 45 ... second objective lens

46, 56 ... astigmatism lens 47 ... photodetector 57 ... first photodetector

58 ... Second optical detector 60 ... Actuator 61 ... Base

63 ... Holder 67 ... Bobbin 69 ... Suspension

71 ... first magnet 72 ... second magnet 73 ... first outer yoke

74 ... second outer yoke 81 ... magnetic layer 82 ... first dielectric layer

83 ... first pattern coil 84 ... second dielectric layer 85 ... second pattern coil

86 ... Third dielectric layer 87 ... Connection 88 ... Contact hole

According to an aspect of the present invention, there is provided a compatible optical pickup apparatus including a light source, a beam splitter for changing a traveling path of incident light, an objective lens disposed between the light source and the disc and focusing the incident light onto the disc, And a photodetector for detecting an information and an error signal by receiving the light reflected from the disk and passed through the beam splitter, A first objective lens disposed at a predetermined distance from the actuator and having different numerical apertures; and a second objective lens, wherein the beam emitted from the light source is selectively incident on the first objective lens and the second objective lens And is provided so as to be able to be transported so as to be directed toward the objective lens.

Preferably, the actuator includes a base on which the light source, the beam splitter, and the photodetector are located; A bobbin fixed on the base, to which the objective lens is fixed; A suspension having one end fixed on the base and movably supporting the bobbin; And magnetic drive means for driving the bobbin in a disk track radial direction and in a disk focus direction.

The magnetic driving means may include a pair of first and second magnets provided on the base so as to face each of two sides of the bobbin parallel to the disk track radial direction; A magnetic layer formed on the side surfaces of the bobbin facing the first and second magnets; A first dielectric layer deposited and formed on the magnetic layer; A first pattern coil formed to be vapor-deposited around the bobbin so that the bobbin is driven in a focus direction of the disc; A second dielectric layer formed on the side of the bobbin facing the first and second magnets on the first pattern coil, and a portion facing the first magnet on the second dielectric layer and a portion facing the first magnet on the second dielectric layer, A second pattern coil provided on each of the first pattern coil and the second pattern coil so that the bobbin is driven in the disc track direction; And a third dielectric layer formed on the second pattern coil by vapor deposition.

Hereinafter, embodiments according to the present invention will be described in detail with reference to the accompanying drawings.

3 is a schematic configuration diagram showing the optical arrangement of a compatible optical pickup device according to an embodiment of the present invention. As shown in the figure, the compatible optical pickup apparatus includes, in its optical configuration, a light source 41, a beam splitter 43, an objective lens 44 (45), an actuator 60 and a photodetector 47 do. The light source 41 generates and emits laser light of a predetermined wavelength. This light source 41 is made of a conventional semiconductor laser. The beam splitter 43 is disposed on the optical path between the light source 41 and the disk 10 so that light incident on the light source 41 is reflected and guided to the disk 10, The light incident from the disk 10 passes straight through and guides the light toward the photodetector 47. The objective lenses 44 and 45 include a first objective lens 44 and a second objective lens 45 that are spaced apart from the actuator 60 by a predetermined distance and have different numerical apertures. The first objective lens 44 preferably has a numerical aperture of 0.6, and is suitable when the CD 10b is adopted as a disk. On the other hand, it is preferable that the numerical aperture of the second objective lens 45 is 0.45, and it is suitable when the DVD 10a is adopted as a disk. The actuator 60 drives the first and second objective lenses 44 and 45 in the radial direction of the disk 10 and in the direction perpendicular to the disk 10, that is, the focus direction. The photodetector 47 receives the light reflected by the disk 10 and transmitted through the beam splitter 43 to detect a focus error signal and a track error signal. The photodetector 47 includes two or more division plates.

The beam splitter 43 and the photodetector 47 are installed such that light emitted from the light source 41 is selectively directed to the first objective lens 44 and the second objective lens 45 do.

Therefore, when the CD 10b is used as the disk, the beam splitter 43 and the photodetector 47 are provided at the position A indicated by the solid line on the bottom surface of the first objective lens 44, And guides the incident light to pass through the first objective lens 44. When the DVD 10b is used as a disk, the beam splitter 43 and the photodetector 47 are provided at a position B indicated by a dotted line on the bottom surface of the second objective lens 45, And guides the incident light to pass through the second objective lens 45.

The present invention further includes a collimating lens 42 that focuses the divergent light emitted from the light source 41 on the optical path between the light source 41 and the beam splitter 43 to convert the divergent light into parallel light . Further, it is preferable to further include an astigmatic lens 46 on the optical path between the beam splitter 43 and the photodetector 47.

4 is a layout diagram showing an optical configuration of a compatible optical pickup device according to another embodiment of the present invention. The beam splitter 53, the first and second objective lenses 44 and 45, the actuator 60, and the photodetectors 57 and 58 in its optical configuration, . The light source 41, the beam splitter 53, the first and second objective lenses 44 and 45, and the actuator 60 are substantially the same as the members described with reference to FIG. 3, The detailed description thereof will be omitted.

The photodetector includes a first photodetector 57 and a second photodetector 58 and is fixedly disposed at a position corresponding to the first objective lens 44 and the second objective lens 45, There are those features. When the beam splitter 53 is moved to the A 'position and the B' position, the light path of the light incident from the light source 41 is guided by the first objective lens 44 or the second objective lens 45). In addition, the present invention may further include a collimating lens 42 and an astigmatic lens 56 at predetermined positions on the optical path, as described in the embodiment. That is, the collimating lens 42 is fixedly disposed on the optical path between the light source 41 and the beam splitter 53, and the astigmatic lens 56 is arranged so as to be movable with the beam splitter 53 do.

The configuration of the above-described actuator 60 of the compatible optical pickup device according to the embodiments of the present invention described with reference to FIG. 3 and FIG. 4 will be described with reference to FIGS. 5 to 8.

FIG. 5 is a schematic plan view showing an actuator according to the present invention, and FIG. 6 is an enlarged sectional view of a portion VI of FIG. Here, the y axis represents the radial direction of the disk, the x axis represents the tangential direction of the disk, and the z axis (see Figs. 7 to 9) represents the focus direction.

A holder 63 provided on the base 61 and first and second objective lenses 44 and 45 are mounted on the base 61 in the radial direction (y-axis direction) A suspension 69 for connecting the bobbin 67 to the holder 63 and magnetic drive means for moving the bobbin 67 by a magnetic force.

The base 61, the bobbin 67, and the suspension 69 are substantially the same as or similar to those of the conventional members described with reference to FIG. 2 in the structure and function thereof, and thus a detailed description thereof will be omitted.

The holder 63 is supported by the suspension 69 so that the first objective lens 44 and the second objective lens 45 are spaced apart from each other by a predetermined distance, Direction and the disc track direction.

The magnetic driving means includes a pair of first and second magnets 71 and 72 provided on the base 61 so as to face each of two sides of the bobbin 67 parallel to the disk radial direction (y-axis direction) And a coil portion formed on the outer side of the bobbin 67.

Each of the first magnet 71 and the second magnet 72 is fixed to the first outer yoke 73 and the second outer yoke 74 on the base 61.

The coil portion is integrally formed on the outer side of the bobbin 67 by deposition and etching and includes a magnetic layer 81, a first dielectric layer 82, and a first pattern 82 which are sequentially stacked on the bobbin 67 with a base 61, A coil 83, a second dielectric layer 84, a second pattern coil 85, and a third dielectric layer 86. The magnetic layer 81 is preferably formed of a ferromagnetic material and is formed on the side surfaces of the bobbin 67 facing the first and second magnets 71 and 72, respectively. This magnetic layer 81 serves as an inner yoke (37a, 37b in Fig. 2) included in a typical actuator. The first dielectric layer 82 is formed of a material such as SiO to be formed as a deposited layer for electrically separating the magnetic layer 81 and the first pattern coil 83 from each other.

7, the first pattern coil 83 is spirally formed around the bobbin 67 by vapor deposition and etching so as to surround the bobbin 67, and the bobbin 67 ) Is driven in the focus direction of the disc. Both ends 83a of the first pattern coil 83 are exposed to the outside so that external power can be applied. The first pattern coil 83 is made of a metal material such as aluminum (Al), copper (Cu), platinum (Pt), or silver (Ag)

6, the second dielectric layer 84 is disposed between the first pattern coil 83 and the second pattern coil 85 and is a layer for electrical insulation between two layers, 1 dielectric layer 82 as shown in FIG.

The second pattern coil 85 is formed on the second dielectric layer 84 by a pair of deposition and etching processes on the portion facing the first magnet 71 and the portion facing the second magnet 72, So that the bobbin 67 is driven in the disk track direction. The shape of the second pattern coil 85 will be described with reference to FIG. As shown in the figure, a pair of second pattern coils 85 facing the first magnet 71 or the second magnet 72 are formed in a helical shape with their coil patterns, and the helical rotation directions are opposite to each other Respectively. One end 85a of the pair of second pattern coils 85 is exposed to the outside and the other end 85b of the pair of second pattern coils 85 is connected to each other by a connecting portion 87 described later formed outside the third dielectric layer 86 . Accordingly, when external power is applied, a current is applied to the coils located inside the pair of second pattern coils 85 in one direction. The magnets 71 and 72 arranged as shown by the dotted lines in FIG. 8 face the inside of the second pattern coil 85. The second pattern coil 85 is substantially made of the same material as the first pattern coil 83.

Referring to FIG. 6, the third dielectric layer 86 may form a connection 87 connecting the one end of the second pattern coil 85 with the layer deposited on the second pattern coil 85 And prevents the second pattern coil 85 from being damaged. A contact groove 88 is formed in a part of the third dielectric layer 86 so that the end of the second pattern coil 85 is exposed to the outside. And an external current is connected to the second pattern coil 85 through the contact groove 88. 9, it is preferable that the connecting portion 87 connects between the inner ends 85b of the pair of second pattern coils 85, and the connecting portion 87 is not short-circuited with the second pattern coil 85 On the third dielectric layer (86).

The actuator for the optical pickup according to the present invention is provided with the bobbin 67 by the current applied to the first pattern coil 83 and the mutual electromagnetic force between the first and second magnets 71, The bobbin 67 can be moved in the radial direction of the disk 71 by the current applied to the second pattern coil 85 and the mutual electromagnetic force between the first and second magnets 71 and 72 Lt; / RTI >

As described above, the compatible optical pickup apparatus according to the present invention employs two objective lenses suitable for discs of different formats, and also performs recording / reproducing of information without deterioration of optical efficiency by movably arranging the beam splitter . Further, since the coils are integrally provided on the outer side of the bobbin of the actuator through deposition and etching, the mass of the actuator can be greatly reduced, thereby reducing the load required for transferring the compatible optical pickup device in the radial direction of the disk. In addition, by forming the coil in a thin pattern, the size can be reduced.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the invention.

Therefore, the true scope of the present invention should be determined by the technical idea of the claims.

Claims (7)

A light source; A beam splitter for changing the traveling path of incident light; An objective lens disposed between the light source and the disk to focus incident light on the disk; An actuator on which the objective lens is mounted; And a photodetector for receiving the light reflected from the disc and passing through the beam splitter to detect information and an error signal, The objective lens includes a first objective lens disposed at a predetermined distance from the actuator and having different numerical apertures; And a second objective lens, The actuator includes a base on which the light source, the beam splitter, and the photodetector are located; A bobbin fixed on the base, to which the objective lens is fixed; A suspension having one end fixed on the base and movably supporting the bobbin; And magnetic drive means for driving the bobbin in a disk track radial direction and in a disk focus direction, Wherein the beam splitter is provided such that light emitted from the light source is selectively transportable so as to be directed to the first objective lens and the second objective lens. The magnetic recording and reproducing apparatus according to claim 1, wherein the magnetic driving means comprises: a pair of first and second magnets provided on the base so as to face each of two sides of the bobbin parallel to the disk track radial direction; A magnetic layer formed on the side surfaces of the bobbin facing the first and second magnets; A first dielectric layer deposited and formed on the magnetic layer; A first pattern coil formed to be vapor-deposited around the bobbin so that the bobbin is driven in a focus direction of the disc; A second dielectric layer deposited on the side of the bobbin facing the first and second magnets on the first pattern coil; A second pattern coil disposed on the second dielectric layer such that the bobbin is driven in the disk track direction by a pair of the first and second magnets facing the first magnet and the second magnet, respectively; And a third dielectric layer deposited and formed on the second pattern coil. 3. The device according to claim 2, wherein each of the pair of second pattern coils facing the first magnet is connected to one end of the second pattern coil by a connection portion formed outside the third dielectric layer, Pickup device. 3. The device according to claim 2, wherein each of the pair of second pattern coils facing the second magnet is connected to one end of the second pattern coil by a connection portion formed outside the third dielectric layer, Pickup device. The compatible optical pickup apparatus according to claim 1, wherein the numerical aperture of the first objective lens is 0.6 and the numerical aperture of the second objective lens is 0.45. 2. The objective lens of claim 1, wherein the photodetector comprises: a first photodetector which is reflected from the disk and passes through the first objective lens and receives light passing through the beam splitter; And a second photodetector for receiving light passing through the beam splitter. 2. The compatible optical pickup apparatus of claim 1, wherein the photodetector is provided so as to be transportable together with the beam splitter so as to receive light transmitted through the beam splitter.