KR100694033B1 - Compatible optical pickup apparatus - Google Patents

Abstract

A light source in which at least two surface light lasers are integrated so as to emit light of two wavelengths or more, an objective lens having an annular lens area and a circular axis area in the form of a paraxial region ring around a vertex, and a light reflected from a recording medium Arranged on the optical path between the photodetector and the light source and the objective lens, most of the light incident from the light source is transmitted straight to enter the objective lens, and most of the light reflected from the recording medium is diffracted and directed to the photodetector. A compatible optical pickup apparatus including a hologram element is disclosed.

Such a compatible optical pickup device employs a light source of a surface light laser that emits light of two wavelengths or more, and the light source and the photodetector are provided on the same base, so that the structure and the optical arrangement are simple.

In addition, when a dummy member made of a transparent material is provided between the hologram element serving as the optical path converting means and the light source, the light source and the photodetector and the objective lens can be integrated.

Description

Compatible optical pickup apparatus

1 is a view schematically showing an example of a conventional compatible optical pickup device;

2 is a view schematically showing an optical configuration of a compatible optical pickup device according to an embodiment of the present invention;

3 and 4 are respectively a perspective view schematically showing the structure of a light source according to the present invention,

5 is a plan view schematically showing the structure of an objective lens according to the present invention;

6 to 8 schematically show an optical configuration of a compatible optical pickup device according to another embodiment of the present invention.

<Description of Symbols for Main Parts of Drawings>

40 ... recording medium 40a, 40b, 40c ... first to third recording medium 45 ... base

50,310 ... light source 50a, 50b ... first and second surface light laser 60 ... hologram element

65.Dummy 70,370 ... Objective lens 100a, 100b, 390 ... Photodetector

200 ... Compatible pickup 300 ... Single pickup

320 ... optical path switching means 350 ... actuator

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a compatible optical pickup apparatus, and more particularly, to a compatible optical pickup apparatus capable of adopting a plurality of recording media having different formats by using light having different wavelengths.

In general, an optical pickup device is a device that performs recording / reproducing of information on a recording medium in a non-contact manner. An optical pickup apparatus capable of recording / reproducing a DVD having a thickness of 0.6 mm employs an objective lens having a numerical aperture of 0.65 and a light source that emits light having a wavelength of 650 nm. At this time, the DVD optical pickup device must be compatible with the existing CD family having a thickness of 1.2mm.

In view of this, conventionally, disc compatible optical pickup devices having different formats have been proposed.

Among conventional compatible optical pickup devices, a compatible optical pickup device that focuses on overcoming problems caused by the difference in thickness between discs uses a single light source. In other words, the compatible optical pickup apparatus employs a light source that emits light having a short wavelength (approximately 650 nm) suitable for the DVD format.

However, a compatible optical pickup device employing such a single light source is impossible to employ CD-R, which, as is widely known, has a 650 nm wavelength region due to the difference in sensitivity since CD-R has an organic dye recording layer. This is because a serious problem of destroying the data recorded on the CD-R is caused when using the light.

Therefore, the conventional optical pickup apparatus for the CD series and DVD series discs has a structure in which two light sources 1 and 3 emit light of different wavelengths, as shown in FIG. .

Referring to FIG. 1, the first light source 1 emits light having a wavelength of 635 nm and is used to record / reproduce the DVD 10a having a relatively thin thickness. The second light sources 3 and 3 emit light of 780 nm wavelength and are used to record / reproduce the CD 10b having a relatively thick thickness.

The light emitted from the first light source 1 side passes through the first beam splitter 7 and is then reflected by the second beam splitter 9 to be directed toward the disc 10. Light emitted from the second light source 3 is sequentially reflected by the first and second beam splitters 7 and 9 to be directed toward the disk 10. The objective lens 15 focuses the light incident from the first and second light sources 1 and 3 to form a light spot on the disk 10. At this time, the light emitted from the first light source 1 is formed in the DVD 10a having a relatively thin thickness, and the light emitted from the second light source 3 is formed in the CD 10b having a relatively thick thickness.

On the other hand, the light reflected from the disk 10 is incident on the second beam splitter 9 via the objective lens 15, and passes through most of the second beam splitter 9 and is received by the photodetector 19. .

Here, reference numeral 5 denotes a grating which diffracts the light incident from the second light source 3 side into 0th order and ± 1st order light so as to detect the tracking error signal by the 3-beam method during CD 10b recording / reproducing. Reference numeral 11 denotes a collimating lens for converting divergent light incident from the first and second light sources 1 and 3 into parallel light, and reference numeral 17 is reflected from the disk 10 and the second beam splitter 9 The photodetecting lens 17 is configured to focus the incident light through the light and to be received by the photodetector 19.

The conventional compatible optical pickup apparatus as described above includes two light sources 1 and 3 for emitting light of different wavelengths, so that both CD-based and DVD-based disks can be employed.

However, the conventional compatible optical pickup apparatus as described above has a structure in which two light sources 1 and 3 are separated and disposed independently of each other, and the structure is complicated and assembly and optical arrangement are difficult. .

SUMMARY OF THE INVENTION The present invention has been made in view of the above, and provides a compatible optical pickup device that employs a light source made of a surface light laser that emits light of two wavelengths or more, thereby simplifying its structure and simplifying optical arrangement. There is this.

A compatible optical pickup apparatus according to the present invention for achieving the above object is a light source including at least two surface light lasers that emit light having different wavelengths suitable for a plurality of recording media having different formats and neighboring each other. and; An objective lens having a paraxial region, a ring-shaped annular lens region, and a circular-axis region around a vertex to focus light incident from the light source to form light spots suitable for recording media of different formats; A photodetector for receiving the light reflected from the recording medium to detect the information signal and the error signal; Disposed on the optical path between the light source and the objective lens, the light incident from the light source is mostly transmitted straight to be incident to the objective lens, and most of the light reflected from the recording medium is diffracted and transmitted to the photodetector. And a hologram element, wherein the light source and the photodetector are installed on the same base.

In this case, the light source may include: a first surface light laser for emitting light having a wavelength of approximately 635 nm or 650 nm so as to be suitable for a DVD-based recording medium having a relatively thin thickness; And a second surface light laser that emits light having a wavelength of approximately 780 nm so as to be suitable for a CD-based recording medium having a relatively thick thickness, wherein the first and second surface light lasers are manufactured as a single body through a semiconductor process or It is preferable that each one is manufactured separately and then installed integrally on one substrate.

On the other hand, it is preferable to further include a dummy member made of a transparent material for transmitting light between the light source and the hologram element, it is possible to integrate the light source, the light detector, the hologram element and the objective lens by the dummy member.

Meanwhile, a compatible optical pickup apparatus according to the present invention for achieving the above object includes at least two surface light lasers that emit light having different wavelengths suitable for a plurality of recording media which are adjacent to each other and have different formats. A light source; An objective lens having a paraxial region, a ring-shaped annular lens region, and a circular-axis region around a vertex to focus light incident from the light source to form light spots suitable for recording media of different formats; A photodetector for receiving the light reflected from the recording medium to detect the information signal and the error signal; An optical path conversion disposed on an optical path between the light source and the objective lens to convert the incident path of the incident light so that light incident on the light source is incident on the objective lens and reflected from the recording medium is directed to the photodetector The light source and the photodetector are provided on the same base, and the light source, the photodetector, and the objective lens are integrated by the optical path changing means.

According to a feature of the present invention, the optical path converting means includes: a beam splitting surface adapted to transmit light of one polarization incident from the light source side and to reflect light of another polarization incident from the recording medium side; An optical member having a reflective surface for reflecting light reflected from the beam splitting surface to face the photodetector; A wavelength plate integrally provided at a side of the optical member facing the recording medium, and converting the polarized light of the incident light so that most of the light reflected from the recording medium is reflected by the beam splitting surface to face the reflective surface. The light source and the photodetector are coupled to one side of the optical member, and the wavelength plate and the objective lens are sequentially coupled to the opposite side, so that the light source, the photodetector and the objective lens are integrated.

According to another feature of the invention, the optical path converting means, the light incident from the light source side is transmitted through the most straight so that the incident to the objective lens, the light reflected from the recording medium is mostly diffracted and transmitted to the photodetector And a dummy member made of a transparent material disposed between the light source and the hologram element to face the light source, wherein the light source and the photodetector are coupled to one side of the dummy member, and opposite to the opposite side. It is preferable that the hologram element and the objective lens are sequentially coupled so that the light source, the photodetector and the objective lens are integrated.                     

In addition, a compatible optical pickup device according to the present invention for achieving the above object, and a compatible pickup unit that is capable of adopting compatible first and second recording media of different formats; And a single pickup unit adapted to employ a third recording medium in a format different from that of the first and second recording carriers, wherein the compatible pickup unit comprises: a first light emitting unit suitable for emitting light suitable for the first and second recording media; 1 light source; A first having a paraxial region, a ring-shaped annular lens region, and a circular axis region around the vertex to focus light incident on the first light source to form a light spot suitable for the first and second recording media of different formats, respectively; An objective lens; A first photodetector provided at one side of the light source to receive light reflected from the first and second recording media to detect an information signal and an error signal; Light disposed on the optical path between the first light source and the first objective lens and incident from the first light source is incident on the first objective lens, and the light reflected from the first and second recording media is incident. And a first optical path converting means for converting a traveling path of incident light toward the first photodetector, wherein the first light source, the first light detector, and the first objective lens are integrated by the first optical path converting means. And the single pick-up section comprises: a second light source for emitting light in a wavelength region suitable for the third recording medium; A second objective lens for focusing the light incident from the second light source to form a light spot on the third recording medium; Second optical path converting means disposed on an optical path between the second light source and the second objective lens to convert a traveling path of incident light; And a second photodetector that is reflected from the third recording medium and receives an incident light through the second objective lens and the second optical path changing means to detect an information signal and / or an error signal. The first and third recording media different from each other can be used interchangeably.                     

The first to third recording media are CD, DVD and HD-DVD recording media, respectively, and the first light source emits light having a wavelength of about 780 nm so as to be suitable for the first recording medium. A first surface light laser; And a second surface light laser emitting light having a wavelength of approximately 635 nm or 650 nm so as to be suitable for the second recording medium, wherein the first and second surface light lasers are manufactured as a single body through a semiconductor process, or The second light source emits light in a blue wavelength region so as to be suitable for a third recording medium having a higher density than the first and second recording mediums.

Here, the compatible pick-up unit is preferably mounted on the actuator of the second objective lens and used for detecting relative inclination between the third recording medium and the second objective lens.

Hereinafter, preferred embodiments of the compatible optical pickup apparatus according to the present invention will be described in detail with reference to the accompanying drawings.

Referring to FIG. 2, a compatible optical pickup apparatus according to an exemplary embodiment of the present invention is configured to focus a light source 50 and light incident from the light source 50 to be suitable for recording media 40 of different formats. An optical path disposed between the objective lens 70 forming an optical spot, the photodetectors 100a and 100b for receiving light reflected from the recording medium 40, and the light source 50 and the objective lens 70 It comprises a hologram element 60 functioning as a converting means.

The light source 50 is provided adjacent to each other, and at least two surface light lasers, for example, DVD-based recording mediums, which emit light suitable for a plurality of recording mediums 40a and 40b having different formats, respectively. The first surface light laser 50a for the relatively thin first recording medium 40a, and the second surface light for the second thick recording medium 40b, such as the CD series recording medium. The laser 50b is provided.

The first surface light laser 50a emits red light having a wavelength of approximately 635 nm or 650 nm. The light emitted from the first surface light laser 50a is focused by the objective lens 70 to form light spots on the information recording surface of the relatively thin first recording medium 40a. The second surface light laser 50b emits infrared light having a wavelength of approximately 780 nm. The light emitted from the second surface light laser 50b is focused by the objective lens 70 to form light spots on the information recording surface of the relatively thick second recording medium 40b.

On the other hand, in general, the surface light laser emits light in the stacking direction, unlike the edge-emitting laser that emits light laterally with respect to the stacked structure of the semiconductor material layer, it is easy to arrange the two-dimensional array structure. In addition, the surface light laser can be formed to a size of several tens of micrometers (μm).

Therefore, by using the characteristics of the surface light laser, the light source 50 according to the present invention is the first and second surface light laser in a position close to each other where the aberration caused by the light emitted from different positions is not a problem. It is formed by arranging 50a and 50b.

For example, as shown in FIG. 3, the light source 50 manufactures the first and second surface light lasers 50a and 50b as separate laser elements, respectively, and then the first and second light sources 50. The surface light laser 50a and 50b elements may be formed in a hybrid type by being integrally installed and wire-bonded on one substrate 52 so as to be electrically insulated from each other. At this time, between the first and second surface light laser (50a, 50b) element is electrically insulated by a blocking plate 54 made of an insulating material formed vertically across the two surface light laser as shown Or leave space to electrically insulate.

The first and second surface light lasers 50a and 50b are sequentially disposed on the substrate 52, for example, the lower electrode layer 51, the lower reflector layer 53, the active layer 55, the upper reflector layer 57, and An upper electrode layer 59 is provided. In the upper electrode layers 59 of the first and second surface light lasers 50a and 50b, the windows 59a and 59b respectively generated by the active layer 55 and the light passing through the upper reflector layer 57 are emitted. ) Is provided.

Here, since the semiconductor layer structure and the material of each of the first and second surface light lasers 50a and 50b are well known, they are simply denoted by the same reference numerals and detailed description thereof will be omitted.

Alternatively, the light source 50 may, for example, stack a semiconductor structure of, for example, the first surface light laser 50a on the semiconductor substrate 52, and then the lower reflector layer 53. At least a portion of the second surface light laser 50b is etched, and the semiconductor 51 of the second surface light laser 50b is laminated on the etched position to manufacture a single body, and the electrode 51 After forming (59), it may be formed of a monolithic (Monolithic) type wire-bonded. Between the first and second surface light lasers 50a and 50b, a space is provided so as to be spaced apart from each other by at least a part of the lower reflector layer 53, or electrically insulated by laminating an insulating material in the space. Let's do it.

Here, the semiconductor layer structure and the material of each of the first and second surface light lasers 50a and 50b of FIG. 4 are substantially the same as those of FIG. 3.

2 to 4, the light source 50 includes a first surface light laser 50a emitting light of 635 or 650 nm wavelength and a second surface light laser 50b emitting light of 780 nm wavelength, The example shows that the DVD-based recording medium 40a and the CD-based recording medium 40b including CD-R can be used interchangeably, and the number of surface light lasers can be added as needed. to be.

The objective lens 70 is mounted on and driven by an actuator (not shown) for focusing and tracking control, and focuses light incident from the light source 50 to be suitable for recording media 40 of different formats. 5, the paraxial region 71, a ring-shaped annular lens region 73, and a circular axis region 75 are formed around the vertex. Here, the vertex is a point where the central axis of the objective lens 70 and the surface of the objective lens 70 meet.

The annular lens area 73 is an area in which light in an intermediate region between the paraxial region 71 and the circular axis region 75 of incident light is incident, and faces or faces the light source 50 of the objective lens 70. It is formed in the shape of an oval ring or a circular ring on the side facing the medium 40.

As described above, as the objective lens 70 of the present invention having the paraxial region 71, the annular lens region 73, and the circular axis region 75, Korean Patent Application Nos. 97-4273, 96- An objective lens having an annular lens area as proposed by Nos. 3605, 96-13918 and the like is employed.

For example, when the objective lens 70 of the present invention employs the objective lens 70 having an aspheric shape as proposed through Patent Application No. 97-4273, the ring lens region 73 is relatively When the thin first recording medium 40a is employed, the light passing through the paraxial region 71 and the circular axis region 75 of the light emitted from the first surface light laser 50a is transferred to the first recording medium 40a. Light collected on an information recording surface as a single light spot and passing through the annular lens region 73 which is an intermediate region between the paraxial region 71 and the circular axis region 75 is transferred from the information recording surface of the first recording medium 40a. The information is scattered so that it cannot be read.

When the second recording medium 40b having a relatively thick thickness is employed, the light passing through the paraxial region 71 and the annular lens region 73 of the light emitted from the second surface light laser 50b is transmitted to the second recording medium 40b. The information recording surface of the recording medium 40b is condensed into a single light spot, and the light passing through the circular axis area 75 is scattered to such an extent that information cannot be read from the information recording surface of the second recording medium 40b.

As described above, when the objective lens 70 having an aspherical shape with the annular lens area 73 is adopted, the compatible optical pickup apparatus according to the present invention can adopt CD and DVD series recording media. Laser disks that require a smaller light spot than those of the recording medium can also be compatible.

In addition, when the objective lens 70 of the present invention employs the objective lens 70 formed to block or scatter incident light as proposed through the patent application No. 96-3605, the relative lens 70 When the first recording medium 40a having a thin thickness is adopted, the light passing through the paraxial region 71 and the circular axis region 75 of the light emitted from the first surface light laser 50a is transferred to the first recording medium 40a. Is condensed into a single light spot on the information recording surface, and the light passing through the annular lens area 73 is blocked or scattered and cannot be condensed on the information recording surface of the first recording medium 40a.

When the relatively thick second recording medium 40b is employed, the light passing through the paraxial region 71 of the light emitted from the second surface light laser 50b is applied to the information recording surface of the second recording medium 40b. Condensed into a single light spot. On the other hand, the light passing through the circular axis region 75 is not focused on the information recording surface of the second recording medium 40b at an intensity suitable for recording and / or reproduction, and the light passing through the annular lens region 73 As described above, it is blocked or scattered so that it cannot be focused on the information recording surface of the second recording medium 40b.

The photodetectors 100a and 100b are provided to correspond to the number of surface light lasers of the light source 50, and are divided into a plurality of parts so as to detect focus and tracking error signals. Accordingly, the photodetectors 100a and 100b receive light emitted from the first and second surface light lasers 50a and 50b and reflected from the first and second recording media 40a and 40b, respectively. To detect the information signal and the error signal.

In this case, the focus error signal may be detected by, for example, the beam size method, and the tracking error signal may be detected by the push-pull method, for example, in the compatible optical pickup device structure.

The hologram element 60 is disposed on an optical path between the light source 50 and the objective lens 70, and most of the light incident from the light source 50 passes through the objective lens 70 to enter the objective lens 70. Most of the light reflected by the recording medium 40 and incident thereon is diffracted and directed to the photodetectors 100a and 100b.

In this case, since the wavelengths of the light emitted from the first and second surface light lasers 50a and 50b are different from each other, the light reflected from the first and second recording mediums 40a and 40b is reflected in the hologram element ( Diffracted at different angles at 60, respectively, and are received by corresponding photodetectors 100a and 100b.

As the hologram device 60, a polarization hologram device using a non-polarization hologram device or a polymer or a birefringent material may be used, and since it is well known, its detailed description will be omitted. Since the light emitted from the first and second surface light lasers 50a and 50b is generally linearly polarized light in one direction, the polarized light that passes the incident light to the hologram element 60 according to the linearly polarized light component or passes through it is diffracted. When employing a hologram element, it is preferable to further include a wave plate (not shown) on the optical path between the polarizing hologram element and the objective lens 70, the wave plate is the first and second surface light employed It is optimized in consideration of various conditions such as the optical output degree of the lasers 50a and 50b and the recording medium of a format requiring a relatively large recording power compared to the optical output of the surface light laser employed. For example, the wave plate includes a quarter wave plate for any one of light having different wavelengths emitted from the first and second surface light lasers 50a and 50b.

Since the compatible optical pickup apparatus according to the exemplary embodiment of the present invention includes the hologram element 60 as an optical path changing means, the light source 50 and the photodetector 100a and 100b have the same base 45. Can be installed on In particular, since the light source 50 includes first and second surface light lasers 50a and 50b for emitting light in the semiconductor stacking direction, the light source 50 and the photodetector 100a ( 100b) modules can be integrated. Here, the light source 50 and the photodetectors 100a and 100b can also be manufactured on the same semiconductor substrate.

Hereinafter, the operation of the compatible optical pickup apparatus according to the exemplary embodiment will be described with reference to FIGS. 2 to 5.

When the relatively thin first recording medium 40a is used as the recording medium 40, the light emitted from the first surface light laser 50a passes straight through the hologram element 60 and the objective lens 70 is used. Through the information recording surface of the first recording medium 40a. Thereafter, the light is reflected from the first recording medium 40a and diffracted through the hologram element 60 via the objective lens 70 to be formed on the photodetector 100a.

When the second recording medium 40b having a relatively thick thickness is used as the recording medium 40, the light emitted from the second surface light laser 50b is used, and the traveling path of the exiting light is the first surface. It is about the same as the light emitted from the optical laser 50a, and diffracts the hologram element 60 at different angles to form a light detector 100b due to the wavelength difference.

On the other hand, the compatible optical pickup device according to the present invention, as shown in Figure 6, made of a transparent material that transmits the incident light between the hologram element 60 and the light source 50 and the photodetector (100a, 100b) module The dummy member 65 may be further provided so that the optical elements forming the compatible optical pickup apparatus may be integrated.

The dummy member 65 functions as a combiner so that the light source 50, the photodetector 100a, 100b module and the objective lens 70 together with the hologram element 60 may be integrated. That is, the light source 50 and the photodetector 100a and 100b modules are coupled to one side of the dummy member 65, and the objective lens 70 is coupled to the opposite side via the hologram element 60. have.

Although the objective lens 70 is shown as having a flat convex lens shape in FIG. 6, the shape of the objective lens 70 is not limited thereto, and the optical elements of the present embodiment are integrated by the dummy member 65. In order to express efficiently, the objective lens 70 is shown in the same shape as in the drawing.

FIG. 7 schematically shows a compatible optical pickup apparatus according to another embodiment of the present invention, in which the light source 50 and the photodetectors 100a and 100b are installed on the same base 45 so that incident light may be provided. The beam splitting surface 161a and the reflecting surface 161b instead of the hologram element 60 and the dummy member 65 of FIG. 6 in a configuration for converting the path of the path and integrating the optical elements forming the compatible optical pickup device. The optical member 161 having the structure and the wavelength plate 165 for converting the polarization of the incident light is characterized in that it is provided. Here, the same reference numerals as those in Figs. 2 and 6 denote members having substantially the same functions, and thus detailed description thereof will be omitted.

The optical member 161 is composed of at least two prism blocks, and the beam splitting surface 161a transmits light of one polarization incident from the light source 50, and another polarization incident from the recording medium 40. The light is provided to reflect and functions as a polarizing beam splitter. In addition, the reflective surface 161b reflects the light incident on the beam splitting surface 161a to be incident to the photodetectors 100a and 100b. By providing this reflecting surface 161b, the light source 50 and the photodetectors 100a and 100b can be provided in the same base 45 as mentioned above.                     

The wavelength plate 165 is disposed on an optical path between the optical member 161 and the objective lens 70 to convert polarized light of incident light so that the light reflected from the recording medium 40 is reflected on the beam splitting surface 161a. Most of the light is reflected to the reflective surface 161b, thereby increasing the amount of light received by the photodetectors 100a and 100b, that is, increasing the light utilization efficiency. The wavelength plate 165 has a format that requires a relatively large recording power compared to the light output of the first and second surface light lasers 50a and 50b employed and the light output of the surface light laser employed. In consideration of various conditions such as a recording medium, it is desirable to have a quarter wave plate for any one of light having different wavelengths emitted from the first and second surface light lasers 50a and 50b. Do.

In the above description, the compatible optical pickup apparatus according to the exemplary embodiments of the present invention as shown in FIGS. 2, 6, and 7 has been described that the CD-based recording media and the DVD-based recording media are compatible. The high density HD-DVD series recording medium 40 and the DVD series recording medium 40 may be modified to be compatible. In this case, any one of the first and second surface light lasers 50a and 50b emits blue light of approximately 400 nm wavelength band, and the other surface light laser emits red light of approximately 635 or 650 nm wavelength band. It is prepared to exit and the remaining optical elements should be optimized accordingly.

8 schematically shows a compatible optical pickup apparatus according to another embodiment of the present invention, in which not only CD and DVD-based recording media but also HD-DVD-based recording media 40 are compatible. There is a characteristic in that it is possible. That is, the compatible optical pickup apparatus according to the present embodiment includes a compatible pickup unit capable of interchangeably employing a relatively thin first recording medium 40a and a relatively thick second recording medium 40b. 200 and a single pick-up unit 300 adapted to employ a third recording medium 40c of the HD-DVD series which is higher density than the first and second recording mediums 40b.

The optical configuration of the compatible pickup unit 200 is substantially the same as any one of the compatible optical pickup apparatus according to the embodiments of the present invention described with reference to FIGS. 2, 6 and 7, and FIG. 6 illustrates the case where the configuration of FIG. 6 is employed in the pickup unit 200.

The single pickup unit 300 includes a light source 310 that emits light in a wavelength region suitable for a high density third recording medium 40c such as an HD-DVD recording medium, and light incident from the light source 310. And a light spot formed on the optical lens 370 to focus light spots on the information recording surface of the third recording medium 40c, and between the light source 310 and the objective lens 370. The optical path changing means 320 for converting the path and the light reflected from the third recording medium 40c and incident through the objective lens 370 and the optical path changing means 320 to receive the information signal and the error signal. And a photodetector 390 for detecting. Here, reference numeral 340 is a mirror member that reflects the incident light to change the traveling direction of the light.

The light source 310 emits light of a blue wavelength region, for example, light of approximately 400 nm wavelength region. As this light source 310, a surface light laser or an edge emitting laser can be employed.                     

The objective lens 370 preferably has a higher number of apertures than the objective lens 70 of the compatible pickup unit 200 to form a smaller light spot suitable for recording / reproducing the high density third recording medium 40c. The actuator 350 is driven in the focusing and tracking directions.

As shown in the optical path converting means 320, the incident light is divided at a predetermined split ratio to transmit the light emitted from the light source 310 toward the third recording medium 40c, and the third recording medium 40c. A light splitter may be used to reflect the incident light reflected by the light beam toward the photodetector 390. A polarizing beam splitter (not shown) and a half wave plate (not shown) may be adopted.

On the other hand, the compatible pickup unit 200 is mounted on the actuator 350 for driving the objective lens 370, as shown, when the third recording medium 40c is employed and the objective and the third recording medium 40c It is more preferable to be used for detecting the relative inclination between the lenses 370.

When the third recording medium 40c is employed, the deterioration of the signal largely caused by the relative inclination between the objective lens 370 and the third recording medium 40c due to the high number of openings of the objective lens 370 is corrected. Essentially, a device for detecting the relative inclination between the objective lens 370 and the third recording medium 40c is required. As described above, the compatible pickup unit 200 is used for the inclination detection for the third recording medium 40. When used, there is an advantage that it is not necessary to employ a separate tilt detection device.

Here, the thickness of the third recording medium 40, which is an HD-DVD series, is to be standardized in the future, but the thickness thereof is not determined. In FIG. 8, the third recording medium 40 is a DVD series that has a first recording medium ( It is exemplified as having the same thickness as 40a), and of course, may be different from the first recording medium 40a.

In addition, the compatible optical pickup apparatus according to the present exemplary embodiment is provided such that the single pickup unit 300 records and / or plays back a relatively thick recording medium such as a CD, and the compatible pickup unit 200 includes DVD and HD. It may be arranged to record and / or reproduce DVD-based recording media. In this case, when the single pickup unit 300 is for the CD-based recording medium, the objective lens 370 having a much smaller numerical aperture than the HD-DVD-based recording medium is adopted. Thus, the recording medium 40 and the objective are adopted. Since signal degradation due to the relative inclination between the lenses 370 is much smaller than in the case of HD-DVD series recording media, it is not necessary to necessarily include an inclination detection device. Therefore, in this case, the compatible pickup 200 is not mounted on the actuator 350.

The compatible optical pickup apparatus according to the present invention as described above employs a light source in which at least two surface light lasers are integrated so as to emit light of two wavelengths or more, and since the light source and the photodetector are installed on the same base, the structure And optical placement is simple.

In addition, when a dummy member made of a transparent material is provided between the hologram element serving as the optical path converting means and the light source, or when a part of the optical path converting means is constituted by at least two prism blocks, the light source and the photodetector and the objective lens can be integrated.

Claims (12)

A light source comprising at least two surface light lasers adjacent to each other and emitting light having different wavelengths suitable for a plurality of recording media having different formats; An objective lens having a paraxial region, a ring-shaped annular lens region, and a circular-axis region around a vertex to focus light incident from the light source to form light spots suitable for recording media of different formats; A photodetector for receiving the light reflected from the recording medium to detect the information signal and the error signal; Disposed on the optical path between the light source and the objective lens, the light incident from the light source is mostly transmitted in a straight line to be incident to the objective lens, and the light reflected from the recording medium is mostly diffracted and directed to the photodetector. Hologram element to be; And And a dummy member made of a transparent material for transmitting light between the light source and the hologram element. The dummy member allows the light source, the photodetector, the hologram element, and the objective lens to be integrated. And the light source and the photodetector are installed on the same base. The method of claim 1, wherein the light source, A first surface light laser for emitting light having a wavelength of approximately 635 nm or 650 nm so as to be suitable for a relatively thin DVD-based recording medium; And a second surface light laser for emitting light having a wavelength of about 780 nm so as to be suitable for a CD-based recording medium having a relatively thick thickness. The first and second surface light lasers are manufactured as a single body through a semiconductor process, or are manufactured separately and then integrally installed on a single substrate. delete A light source comprising at least two surface light lasers adjacent to each other and emitting light having different wavelengths suitable for a plurality of recording media having different formats; An objective lens having a paraxial region, a ring-shaped annular lens region, and a circular-axis region around a vertex to focus light incident from the light source to form light spots suitable for recording media of different formats; A photodetector for receiving the light reflected from the recording medium to detect the information signal and the error signal; An optical path conversion disposed on an optical path between the light source and the objective lens to convert the incident path of the incident light so that light incident on the light source is incident on the objective lens and reflected from the recording medium is directed to the photodetector Means; The light source and the photodetector are provided on the same base, The optical path converting means, The beam splitting surface which transmits light of one polarization incident from the light source side and reflects light of the other polarization incident on the recording medium side, and reflects the light incident from the beam splitting surface and reflected from the beam splitting surface An optical member having a reflective surface facing the detector; A wavelength plate integrally provided at a side of the optical member facing the recording medium, and converting the polarized light of the incident light so that most of the light reflected from the recording medium is reflected by the beam splitting surface to face the reflective surface. The light source and the photodetector are coupled to one side of the optical member, and the wavelength plate and the objective lens are sequentially coupled to the opposite side, and the light source, the photodetector, and the objective lens are integrated by the optical path converting means. Compatible optical pickup device. delete A light source comprising at least two surface light lasers adjacent to each other and emitting light having different wavelengths suitable for a plurality of recording media having different formats; An objective lens having a paraxial region, a ring-shaped annular lens region, and a circular-axis region around a vertex to focus light incident from the light source to form light spots suitable for recording media of different formats; A photodetector for receiving the light reflected from the recording medium to detect the information signal and the error signal; An optical path conversion disposed on an optical path between the light source and the objective lens to convert the incident path of the incident light so that light incident on the light source is incident on the objective lens and reflected from the recording medium is directed to the photodetector Means; The light source and the photodetector are provided on the same base, The optical path converting means, A hologram element that transmits most of the light incident from the light source toward the objective lens and enters the objective lens, and most of the light reflected from the recording medium is diffracted and transmitted to the photodetector; And a dummy member made of a transparent material disposed between the light source and the hologram element to transmit light. The light source and the photodetector are coupled to one side of the dummy member, and the hologram element and the objective lens are sequentially coupled to the opposite side, and the light source, the photodetector, and the objective lens are integrated by the optical path converting means. Compatible optical pickup device characterized in that. The method of claim 4 or 6, wherein the light source, A first surface light laser for emitting light having a wavelength of approximately 635 nm or 650 nm so as to be suitable for a relatively thin DVD-based recording medium; And a second surface light laser for emitting light having a wavelength of about 780 nm so as to be suitable for a CD-based recording medium having a relatively thick thickness. The first and second surface light lasers are manufactured as a single body through a semiconductor process, or are manufactured separately and are integrally formed on one substrate and are integrated and formed. A compatible pick-up unit configured to interchangeably adopt first and second recording media having different formats; And a single pickup unit adapted to employ a third recording medium in a format different from that of the first and second recording carriers. The compatible pickup unit, A first light source for emitting light suitable for the first and second recording media; A first having a paraxial region, a ring-shaped annular lens region, and a circular axis region around the vertex to focus light incident on the first light source to form a light spot suitable for the first and second recording media of different formats, respectively; An objective lens; A first photodetector provided at one side of the light source to receive light reflected from the first and second recording media to detect an information signal and an error signal; Light disposed on the optical path between the first light source and the first objective lens and incident from the first light source is incident on the first objective lens, and the light reflected from the first and second recording media is incident. And first optical path converting means for converting a traveling path of incident light to the first photodetector. The single pickup unit, A second light source for emitting light in a wavelength region suitable for the third recording medium; A second objective lens for focusing the light incident from the second light source to form a light spot on the third recording medium; Second optical path converting means disposed on an optical path between the second light source and the second objective lens to convert a traveling path of incident light; And a second photodetector, which is reflected from the third recording medium and receives light incident through the second objective lens and the second optical path conversion means to detect an information signal and / or an error signal. The first to third recording media having different formats can be used interchangeably. The first optical path converting means, A beam splitting surface configured to transmit light of one polarization incident from the first light source and to reflect light of another polarization incident from the first and second recording media, and to enter from the first and second recording media An optical member having a reflecting surface for reflecting light reflected from the beam splitting surface to face the photodetector; The optical member is integrally provided on the side facing the first and second recording media, and converts the polarized light of the incident light so that most of the light reflected from the first and second recording media is reflected on the beam splitting surface to provide the reflective surface. Including a wave plate facing the The first light source and the first photodetector are coupled to one side of the optical member, and the wavelength plate and the first objective lens are sequentially coupled to the opposite side thereof, and the first light source and the first A compatible optical pickup device, characterized in that one optical detector and the first objective lens are integrated. The recording medium of claim 8, wherein the first to third recording media are CD, DVD, and HD-DVD recording media, respectively. The first light source, A first surface light laser for emitting light having a wavelength of approximately 780 nm to suit the first recording medium; And a second surface light laser emitting light having a wavelength of approximately 635 nm or 650 nm so as to be suitable for the second recording medium. The first and second surface light lasers are manufactured as a single body through a semiconductor process, or are separately manufactured and then integrally installed on one substrate, And the second light source emits light in a blue wavelength region to suit a third recording medium having a higher density than the first and second recording media. A compatible pick-up unit configured to interchangeably adopt first and second recording media having different formats; And a single pickup unit adapted to employ a third recording medium in a format different from that of the first and second recording carriers. The compatible pickup unit, A first light source for emitting light suitable for the first and second recording media; A first having a paraxial region, a ring-shaped annular lens region, and a circular axis region around the vertex to focus light incident on the first light source to form a light spot suitable for the first and second recording media of different formats, respectively; An objective lens; A first photodetector provided at one side of the light source to receive light reflected from the first and second recording media to detect an information signal and an error signal; Light disposed on the optical path between the first light source and the first objective lens and incident from the first light source is incident on the first objective lens, and the light reflected from the first and second recording media is incident. And first optical path converting means for converting a traveling path of incident light to the first photodetector. The single pickup unit, A second light source for emitting light in a wavelength region suitable for the third recording medium; A second objective lens for focusing the light incident from the second light source to form a light spot on the third recording medium; Second optical path converting means disposed on an optical path between the second light source and the second objective lens to convert a traveling path of incident light; And a second photodetector, which is reflected from the third recording medium and receives light incident through the second objective lens and the second optical path conversion means to detect an information signal and / or an error signal. The first to third recording media having different formats can be used interchangeably. The first optical path converting means, Most of the light incident from the first light source is transmitted in a straight line to be incident to the first objective lens, and most of the light reflected from the first and second recording media is transmitted through diffraction to be directed to the first photodetector. Hologram element, And a dummy member made of a transparent material disposed between the first light source and the hologram element to transmit light. The first light source and the first photodetector are coupled to one side of the dummy member, and the hologram element and the first objective lens are sequentially coupled to the opposite side thereof, so that the first light source and the first light source are converted by the first optical path converting means. A compatible optical pickup device, characterized in that the photodetector and the first objective lens are integrated. The recording medium of claim 10, wherein the first to third recording media are CD, DVD and HD-DVD recording media, respectively. The first light source, A first surface light laser for emitting light having a wavelength of approximately 780 nm to suit the first recording medium; And a second surface light laser emitting light having a wavelength of approximately 635 nm or 650 nm so as to be suitable for the second recording medium. The first and second surface light lasers are manufactured as a single body through a semiconductor process, or are separately manufactured and then integrally installed on one substrate, And the second light source emits light in a blue wavelength region to suit a third recording medium having a higher density than the first and second recording media. 12. The apparatus according to any one of claims 8 to 11, wherein the compatible pickup unit is mounted on an actuator of the second objective lens and used for detecting relative inclination between the third recording medium and the second objective lens. Compatible optical pickup device.

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