KR200215606Y1 - Compatible Optical Pickup Device - Google Patents

Abstract

Disclosed is a compatible optical pickup apparatus capable of interchangeably employing recording media having different formats.

The disclosed optical pickup apparatus includes a base, first and second light sources disposed adjacent to the base and irradiating laser light of different wavelength regions, and installed on the base and irradiated from the first light source to the recording medium. An optical module having a first photodetector for receiving reflected light; A hologram element disposed on an optical path between the light source and the recording medium, the light irradiated from the first and second light sources going straight to the recording medium, and the light incident from the recording medium toward the first light detector diffracted; An objective lens disposed on an optical path between the hologram element and the recording medium to focus light emitted from the first and second light sources onto the recording medium; A beam splitter disposed on an optical path between the hologram element and the objective lens and converting a traveling path of light irradiated from the first and second light sources and reflected from the recording medium; And a second photodetector for receiving the light transmitted through the beam splitter.

Description

Compatible Optical Pickup Device

The present invention relates to a compatible optical pickup apparatus, and more particularly, to a compatible optical pickup apparatus capable of interchangeably employing a recording medium having a different format.

In general, an optical pickup device is employed in a compact disc player (CDP), a digital multifunction disc player (DVDP), a CD-ROM driver, a DVD-ROM driver, or the like to perform recording / reproducing of information on a recording medium in a non-contact manner.

DVDP and DVD-ROM are attracting attention in the video / audio field as devices capable of high-density recording / playback. The optical pickup device employed in this DVDP employs not only digital video discs (DVDs) but also compact discs (CDs), CD-Rs (Recordables), CD-Is, and CD-Gs as recording media for compatibility. Even if so, it should be possible to record and / or reproduce information.

However, the thickness of the DVD has been standardized to a different specification from the thickness of the CD family due to mechanical disc tilt tolerance and objective lens numerical aperture. That is, the thickness of the existing CD family is 1.2mm while the DVD is 0.6mm. As such, when the CD family and the DVD have different thicknesses, spherical aberration due to the difference in thickness occurs when the optical pickup apparatus for DVD is applied to the CD family. This spherical aberration causes a problem of failing to obtain sufficient light intensity for recording the information signal or deterioration of the signal during reproduction.

Also, in the wavelength of the reproduction light source, DVD has been standardized into a wavelength range different from that of the CD family. That is, while the reproduction light source wavelength for the existing CD family is approximately 780 nm, the reproduction light source wavelength for DVD is approximately 650 nm.

Due to this difference in standardization, since information recorded on a DVD cannot be reproduced by a normal CDP, development of an optical pickup device for a DVD is required. At this time, the optical pickup device for DVD should be compatible with the existing CD family.

As described above, the conventional compatible optical pickup apparatus in consideration of the point, the first light source 21 and the first photodetector 27 to emit light of 780nm wavelength and to receive incident light as shown in FIG. ) Converts a traveling path of light irradiated from the optical module 20 formed integrally with each other, the second light source 31 emitting light having a wavelength of 650 nm, and the first and second light sources 21 and 31, respectively. First and second polarization beam splitters 25 and 33 for reflection, objective lens 17 for focusing incident light onto the disk 10, and reflected from the disk 10 and the first and second polarization beam splitters. And a second photodetector 37 for receiving the incident light through (25) and (33). Here, the first light source 21 is for a relatively thin disk 10a, such as a DVD, and the second light source 31 is for a relatively thick disk 10b, for example, a CD family.

The optical module 20 includes a substrate 22 on which a first light source 21, a first light detector 27, the first light source 21 and the first light detector 27 are installed, and the first light source 21. A housing 24 provided to surround the first light source 21 and the first photodetector 27, and a hologram element 23 that changes the traveling path according to the traveling direction of the light transmitted through the housing 24; It is configured to include.

The first and second polarization beam splitters 25 and 33 have mirror surfaces adapted to selectively transmit or reflect incident light according to the polarization direction, and may be integrally formed as shown in the optical configuration. .

The light irradiated from the first light source 21 is reflected by the first polarized beam splitter 25 toward the disk 10, and the light irradiated from the second light source 31 is the second polarized beam splitter. After being reflected at 33, it passes through the first polarizing beam splitter 25 and is directed toward the disk 10.

A λ / 4-wavelength plate for converting light of linearly polarized light into circularly polarized light and circularly polarized light into linearly polarized light on the side of the objective lens 17 side of the first polarization beam splitter 25. 11 is disposed. In addition, on the optical path between the λ / 4 wavelength plate 11 and the objective lens 17, a reflecting mirror 13 reflecting incident light in consideration of optical arrangement and a collimating lens 15 focusing the incident light Is placed.

The light irradiated from the first light source 21 is reflected by the disk 10b having a relatively thick thickness, and is reflected by the first polarization beam splitter 25. Thereafter, the light is diffracted by the hologram element 23 and then received by the first photodetector 27.

On the other hand, the light irradiated from the second light source 31 is reflected by the disk 10a having a relatively thin thickness, and passes through the first and second polarization beam splitters 25 and 33. This light passes through the detection lens 35 causing astigmatism and is received by the second photodetector 37.

As described above, the conventional compatible optical pickup apparatus constructed is complicated in its configuration and has a large number of parts. Accordingly, there is a disadvantage in that assemblability is lowered and defective factors are increased.

The present invention has been made in view of the above-described disadvantages, and an object thereof is to provide a compatible optical pickup device having a structure of simplifying an optical configuration and reducing a number of components.

1 is a schematic view showing an optical arrangement of a conventional compatible optical pickup device.

2 is a schematic view showing an optical arrangement of a compatible optical pickup device according to an embodiment of the present invention.

<Description of the reference numerals for the main parts of the drawings>

10 Recording medium 40 Optical module 41 Base

42 ... substrate 43 ... lead frame 44 ... wire

45 ... first light source 47 ... first light detector 49 ... second light source

50 Hologram element 51 Hologram pattern 60 Beam splitter

70 ... objective lens 80 ... second photodetector

A compatible optical pickup device according to the present invention for achieving the above object, the base, and the first and second light sources which are installed adjacent to the base and irradiating laser light of different wavelength regions, and on the base An optical module installed at the first light source and having a first light detector configured to receive light emitted from the first light source and reflected from the recording medium; Disposed on an optical path between the light source and the recording medium, the light irradiated from the first and second light sources passes straight toward the recording medium and the light incident from the recording medium is diffracted toward the first photodetector A hologram element to make; An objective lens disposed on an optical path between the hologram element and the recording medium to focus light emitted from the first and second light sources onto a recording medium; A beam splitter disposed on an optical path between the hologram element and the objective lens and converting a traveling path of light irradiated from the first and second light sources and reflected from the recording medium; And a second photodetector for receiving the light transmitted through the beam splitter.

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

Referring to FIG. 2, a compatible optical pickup apparatus according to an exemplary embodiment of the present invention includes an optical module 40 for irradiating two lights having different wavelengths and receiving light incident from the recording medium 10. A hologram element 50 for selectively transmitting straight or diffraction according to the advancing direction, an objective lens 70 for focusing incident light onto the recording medium 10, and between the hologram element 50 and the objective lens 70 It is configured to include a beam splitter 60 disposed on the optical path to convert the advancing path of the incident light and a second photo detector 80 for receiving the light transmitted through the beam splitter 60.

The first optical module 40 includes a base 41, first and second light sources 45 and 49 installed adjacent to the base 41 and irradiating laser light of different wavelength regions; And a first photodetector 41 mounted on the base 41 to receive light emitted from the first light source 45 and reflected from the recording medium 10.

The base 41 and the first and second light sources 45 and 49 and the first photodetector 41 are connected to the outside by a plurality of lead frames 43 and connected by wires 44. A substrate 42 electrically connected to the first and second light sources 45 and 49 and the first photodetector 41 is provided.

Each of the first and second light sources 45 and 49 is a semiconductor laser that emits light of different wavelengths. Preferably, each of the first and second light sources 45 and 49 is a surface light laser that emits light in the stacking direction of the semiconductor material layers. For example, the first light source 45 emits light having an infrared wavelength of about 635 to 650 nm so as to be suitable when the relatively thin disk 10a is employed as the recording medium 10. The two light sources 49 emit light having a red wavelength in the region of about 780 nm so as to be suitable when a relatively thick disk 10b is employed as the recording medium 10.

In addition, the window of the first light source 45 is the second light source 49 so that the emission angle of the light emitted from the second light source 49 is smaller than the emission angle of the light emitted from the first light source 45. It is preferably formed smaller than the window of. Here, the windows of each of the first and second light sources 45 and 49 indicate the size of the portion to which the laser light is irradiated.

The first photodetector 47 is formed on the substrate 42, and is incident on the hologram element 50 after being irradiated from the first light source 45 and reflected by the recording medium 10. The light is received to detect an information signal, a track error signal and a focus error signal of the recording medium 10 by the first light source 45.

The hologram element 50 is provided on the base 41 such that the hologram pattern 51 is spaced apart from the first light source 45 by a predetermined interval. The hologram element 50 directs the light emitted from the first and second light sources 45 and 49 to be directed to the recording medium 10 and to the solid line incident from the recording medium 10. The illustrated light beam is diffracted by the hologram pattern 51 toward the first photodetector 47.

The beam splitter 60 has a plate-like structure or a cube-shaped structure (not shown) as shown in the drawing, and is disposed on an optical path between the hologram element 50 and the objective lens 70. Reflects the light irradiated from the first and second light sources 45 and 49 toward the recording medium 10, and reflects the light rays shown by the solid lines reflected from the recording medium 10 toward the optical module 40. .

The second photodetector 80 receives the light reflected by the recording medium 10 and reflected by the beam splitter 60 to receive incident light, and a focus error signal and a track error for the disk 10b having a relatively thick thickness. Signals and information signals (RF signals) are detected. The second photodetector 80 detects a focus error signal by an astigmatism method using astigmatism generated by the beam splitter 60.

Hereinafter, an operation of a compatible optical pickup apparatus according to an embodiment of the present invention will be described with reference to FIG. 2 as an example in which a relatively thin disk 10a such as a DVD is employed as the recording medium 10. . In this case, effective light is used for the light ray shown by the solid line irradiated from the first light source 45. That is, the divergent light emitted from the first light source 45 passes through the hologram element 50 and is reflected by the beam splitter 60 to travel toward the objective lens 70. The objective lens 70 focuses incident light so as to form a relatively thin disk 10a. The light focused on the disk 10a is reflected back toward the objective lens 70, transmitted through the objective lens 70, and reflected by the beam splitter 60, and then the hologram pattern 51 of the hologram element 50. Is diffracted at and received by the first photodetector 47. From this light receiving signal, an error signal and an information signal for the relatively thin disk 10a can be known.

On the other hand, in the case where the relatively thick disk 10b is employed as the recording medium, light rays indicated by dotted lines irradiated from the second light source 49 are used as the effective light, and the emitted light passes through the hologram element 50. After being reflected by the beam splitter 60, the light is focused by the objective lens 70 to form a relatively thick disk 10b. The light reflected by the disk 10b passes through the objective lens 70 and the beam splitter 60 and is then received by the second photodetector 80. From this light receiving signal, an error signal and an information signal for a relatively thin disk 10b can be obtained.

The compatible optical pickup apparatus according to the present invention configured as described above includes two light sources and two photodetectors having different wavelengths, and the optical pickup structure is simplified by modularizing one light source and the photodetector into one, thereby improving assembly performance. Optical alignment can be facilitated.

Claims (2)

A base, first and second light sources disposed adjacent to the base and irradiating laser light of different wavelength ranges, and received on the base and irradiated from the first light source and reflected from a recording medium An optical module having a first photodetector; Disposed on an optical path between the light source and the recording medium, the light irradiated from the first and second light sources passes straight toward the recording medium and the light incident from the recording medium is diffracted toward the first photodetector A hologram element to make; An objective lens disposed on an optical path between the hologram element and the recording medium to focus light emitted from the first and second light sources onto a recording medium; A beam splitter disposed on an optical path between the hologram element and the objective lens and converting a traveling path of light irradiated from the first and second light sources and reflected from the recording medium; And a second photodetector for receiving the light transmitted through the beam splitter. The surface light laser of claim 1, wherein the first light source is a surface light laser that emits light having an infrared wavelength in its stacking direction, and the second light source is a surface light laser that emits light having a red wavelength in its stacking direction, The window of the first light source is formed smaller than the window of the second light source so that the emission angle of the light emitted from the second light source is smaller than the emission angle of the light emitted from the first light source. The optical pickup apparatus of claim 1, wherein the light irradiated from the light is bound to each of recording media having different thicknesses.