KR20000066585A - Light emitting module and compatible optical pickup apparatus employing it - Google Patents

Abstract

PURPOSE: An optical outputting module and interchangeable optical pick-up device using the module provides a first and second light source in an optical module and use a monitoring optical detector for a plurality of wavelengths, thereby reproducing the number of assembling process and simplifying a wire. CONSTITUTION: An optical outputting module comprises a base(51), a first and second light source(61,63) disposed on the base to radiate laser beams respectively having a different wavelength range, a beam splitter(65) for diverging light radiated from the first and second light source, and a monitoring optical detector(67) for receiving the light radiated from the light source and diverged from the beam splitter and monitoring an optical output of the first and second light source. An interchangeable optical pick-up device using the module comprises the optical outputting module, an object lens disposed on an optical route between the optical outputting module and a recording medium to concentrate the light from the first and second light source on the optical recording medium, a unit for changing an optical route disposed the optical route between the optical outputting module and the object lens to change a passage of incident light, and an optical detector for receiving the light inputted through the unit for changing an optical route.

Description

Light emitting module and compatible optical pickup apparatus employing it

The present invention relates to an optical output module for outputting laser light, and a compatible optical pickup device employing the same. Specifically, an optical output module packaged two light sources for outputting two different light wavelengths into a single module and the same The present invention relates to a compatible optical pickup apparatus capable of employing compatible recording media having different formats.

In general, an optical pickup device is employed in a compact disc player (CDP), a CD-ROM driver, a digital multi-function disc player (DVDP), 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 pick-up apparatus considering the above points includes a first optical module 20 for irradiating light of 650 nm wavelength and a second optical module for irradiating light of approximately 780 nm wavelength as shown in FIG. 1. 30, first and second beam splitters 25 and 35 for converting the traveling paths of the light irradiated from the first and second optical modules 20 and 30, and the incident light to the disk 10. A photodetector 40 reflected from the objective lens 15 and the disk 10 for focusing the light, and receiving light incident through the second beam splitter 35 and the first beam splitter 25. It is configured to include. Here, the first optical module 20 is for a relatively thin disk 10a, such as a DVD, and the second optical module 30 is for a relatively thick disk 10b, for example, a CD family.

As shown in FIG. 2, each of the first optical modules 20 includes a base 21 on which a plurality of lead pins 27 are installed, a heat sink 22 provided on the base 21, and the heat. Monitor light installed on the side of the sink 22 and the base 21, the monitor light for receiving the light irradiated to the rear of the light source 23 to monitor the light output of the light source 23 And a can 29 having a detector 25 and a projection window 28 and surrounding the light source 23 and the monitor photodetector 25. Since the monitor photodetector 25 uses the back light irradiated from the light source 23, the upper limit value of the reflectance of the light source 23 is approximately 50 to 60% in consideration of the rear light output of the light source 23. Need to be limited to

Since the second optical module 30 is substantially the same as the components of the first optical module 20, detailed description thereof will be omitted. However, the light source employed is distinguished from the optical module 20 in that the light of approximately 780 nm wavelength is irradiated.

The first beam splitter 25 has a flat plate-like structure and reflects the light emitted from the first light source 20 to face the second beam splitter 35. The second beam splitter 35 has a cubic structure having a mirror surface configured to transmit or reflect incident light.

The light irradiated from the first optical module 20 is reflected by the first beam splitter 25 and passes through the second beam splitter 35 to face the optical disc 10. The second optical module 30 ) Is irradiated from the second beam splitter 35 and then focused by the objective lens 15 to be formed on the optical disk 10. Here, the grating 13 for diffracting incident light is disposed between the second optical module 30 and the second beam splitter 35.

On the optical path between the second beam splitter 35 and the objective lens 17, a reflection mirror 13 for reflecting incident light in consideration of optical arrangement and a collimating lens 15 for focusing the incident light are disposed.

The light irradiated from the first optical module 20 is received by the photodetector 40 after being reflected by the relatively thin disk 1a, and the light irradiated from the second optical module 30 has a thickness. It is reflected by the relatively thin disk 10b and then received by the photodetector 40. That is, a reproduction signal (Radio Frequency signal) of light irradiated from the first and second optical modules 20 and 30 is detected through the one photodetector 40. Here, a cylindrical lens 19 is disposed between the first beam splitter 25 and the photodetector 40 to cause astigmatism.

The first and second optical modules 20 and 30 and the photodetector 40 of the compatible optical pickup device configured as described above will be described below.

First, the first optical module 20 in which the semiconductor laser 23 for irradiating light having a wavelength of 650 nm is fixed is fixed and emitted from the first optical module 20, and then the first and second beam splitters 25 are fixed. After adjusting the photodetector 40 to position the light reflected from the optical disk via the 35 and the objective lens 11 to the photodetector 40 to enable servo and RF signal reproduction, the adjusted photodetector ( The second optical module 30 is adjusted so that the light incident on the optical fiber 40 after being irradiated by the second optical module 30 is accurately formed.

Therefore, the conventional compatible optical pickup device configured as described above has the following disadvantages.

First, since at least one element of the first optical module, the photodetector, and the second optical module must be adjusted, the assemblability is degraded and the assembling defect is increased.

Second, miniaturization is difficult by employing the first and second optical modules in separate locations.

Third, circuit wiring is complicated because two monitoring photodetectors are required to adjust the light output of each light source.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described disadvantages, and an object thereof is to provide an optical output module having a structure of simplifying an optical configuration and reducing a number of components and a compatible optical pickup apparatus employing the same.

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

2 is a schematic cross-sectional view showing a first optical module employed in FIG.

Figure 3 is a schematic cross-sectional view showing the optical arrangement of the optical output module according to an embodiment of the present invention.

4 is a schematic view showing an optical arrangement of an apparatus for matching light emitting points of first and second light sources of an optical output module according to an embodiment of the present invention.

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

Figure 6 is a graph showing the transmittance characteristics of the beam splitter of the optical output module according to an embodiment of the present invention.

<Description of the code | symbol about the principal part of drawing>

1 ... optical recording medium 50 ... optical output module 51 ... base

52 ... Lead 53 ... Wire 55 ... First Heatsink

56 2nd Heatsink 57 ... Cap 61 ... 1st Light Source

63 2nd light source 65 beam splitter 67 photodetector for monitor

71 ... Grating 73 ... Platform Beam Splitter

75 ... collimating lens 77 ... objective lens 79 ... astigmatism lens

80 ... photodetector

Optical output module according to the present invention for achieving the above object, the base; First and second light sources disposed on the base and irradiating laser light of different wavelength regions; A beam splitter for splitting light emitted from the first and second light sources; And a monitor photodetector configured to receive light emitted from the first and second light sources and branched in one direction from the beam splitter to monitor light output of the first and second light sources.

In addition, the compatible optical pickup device according to the present invention for achieving the above object is a base, and the first and second light sources provided on the base and irradiating laser light of different wavelength ranges, and the first and A beam splitter for dividing the light emitted from the second light source, and the light emitted from the first and second light sources and branched in one direction from the beam splitter to receive the light output of the first and second light sources An optical output module including a monitor photodetector; An objective lens disposed on an optical path between the optical output module and a recording medium to focus light emitted from the first and second light sources onto the optical recording medium; Optical path converting means disposed on an optical path between the optical output module and the objective lens to convert a traveling path of incident light; And a photodetector that is irradiated from the first and second light sources and is reflected from the optical recording medium and receives light incident through the optical path changing means.

Hereinafter, exemplary embodiments of an optical output module and a compatible optical pickup apparatus employing the same according to the present invention will be described in detail with reference to the accompanying drawings.

Referring to FIG. 3, the optical output module 50 according to the present invention includes a base 51 and first and second light sources 61 disposed on the base 51 and irradiating laser light in different wavelength regions. ), The beam splitter 65 for splitting the light emitted from the first and second light sources 61 and 63, and the light split in one direction from the beam splitter 65 to receive the beam splitter. A monitor photodetector 67 for monitoring the light output of the first and second light sources 61 and 63, and installed on the base 51 and the first and second light sources 61 and 63; And a cap 57 surrounding the beam splitter 65 and the monitor photodetector 67.

A first heat sink 55 is further provided on the base 51, and the first light source 61 is installed on the side of the first heat sink 55 to be perpendicular to the base 51. To emit light. The second light source 63 is disposed on an upper surface of the first heat sink 55 to emit light in a direction parallel to the base 51. In addition, a second heat sink 56 having the monitor photodetector 67 provided on a side thereof so that the monitor photodetector 67 faces the second light source 61 with the beam splitter 65 therebetween. ) Is further provided.

The first and second light sources 61 and 63 and the monitor photodetector 67 are externally driven by a plurality of leads 52 and wires 53 installed through the base 51. Is electrically connected to Each of the first and second light sources 61 and 63 is a semiconductor laser that irradiates light of different wavelengths. For example, the first light source 61 emits light having an infrared wavelength in the region of about 635 to 650 nm, and the second light source 63 emits light having a red wavelength in the region of about 780 nm.

The beam splitter 65 is interposed between the first and second light sources 61 and 63 and the monitor photodetector 67, and is irradiated from the first and second light sources 61 and 63. Most of the light is irradiated to the outside of the cap 57 through the exit hole 57a formed in the cap 57 and a part of the light is directed to the photodetector 67 for the monitor.

In this case, the exit hole 57a is preferably sealed by the beam splitter.

Unlike the conventional optical output device described with reference to FIG. 2, the monitor photodetector 67 is configured to cover the beam splitter 65 among the light emitted from the first and second light sources 61 and 63. Use the light branched via. That is, a part of the effective output light irradiated from the first and second light sources 61 and 63 is used. Therefore, since the light irradiated from the first and second light sources 61 and 63 to the rear surface is unnecessary, the structure of the first and second light sources 61 and 63 can be improved to have a reflectance of approximately 99% or more. The light output can be improved. In addition, since the lifetime of the semiconductor laser is proportional to the square of the light output, the lifetime can be significantly extended.

In the optical output module 50 configured as described above, the assembly for making the light emitting points of the first and second light sources 61 and 63 coincide uses an apparatus as shown in FIG.

The light irradiated from the first light source 61 of the light output module 50 and radiated and radiated through the beam splitter 65 is enlarged to the CCD camera 85 through the collimator 81 and the focusing lens 83. Bears. Here, the spot formed on the CCD camera 85 is magnified and observed through the monitor 90, and the position of the first light source 61 is adjusted and then fixed to the side surface of the first heat sink 55. Subsequently, the first heat sink 55 after adjusting the position of the second light source 63 while observing the spot formed on the CCD camera 85 through the monitor 90 after being irradiated from the second light source 63. Fix to the top.

3 and 5, the compatible optical pickup apparatus according to the present invention includes an optical output module 50 in which first and second light sources 61 and 63 are integrally formed, and the first and second light sources. (61) and (63) an objective lens (77) for focusing the light emitted from the optical recording medium (1), optical path changing means for converting a traveling path of incident light, and said first and second light sources (61) ( And a photodetector 80 which is irradiated from the optical recording medium 1 and is reflected by the optical recording medium 1 and then receives light incident through the optical path changing means.

As described with reference to FIG. 3, the optical output module 50 includes a base 51 and first and second light sources disposed on the base 51 and irradiating laser light in different wavelength regions. 61, 63, the beam splitter 65 for splitting the light emitted from the first and second light sources 61, 63, and the first and second light sources 61, 63, And a light detector 67 for receiving the light split in one direction from the beam splitter 65 to monitor the light output of the first and second light sources 61 and 63.

The first light source 61 is an optical recording medium 1, which is used when a relatively thin optical disk 1a, for example, DVD, is employed and emits light in an area of approximately 635 to 650 nm. The second light source 63 emits light in an area of approximately 780 nm, which is used when a relatively thick optical disk 1b, for example, CD, is employed as the optical recording medium 1.

Referring to FIG. 6, the beam splitter 65 transmits approximately 90% of the wavelength in the 650 nm region and approximately 10% of the wavelength in the 780 nm region. As such, since the beam splitter 65 itself having the transmission reflection characteristic according to the wavelength is well known, its detailed description is omitted.

That is, the beam splitter 65 transmits most of the light irradiated from the first light source 61 and reflects a part of the light. And, most of the light irradiated from the second light source 63 reflects and transmits a part of light. Therefore, most of the light irradiated from the first and second light sources 61 and 63 is directed toward the optical recording medium 1 via the beam splitter 65, and only a part of the light is detected by the monitor photodetector ( 67).

The optical path converting means is disposed on an optical path between the optical output module 50, the objective lens 77, and the optical detector 80, and the light irradiated from the optical output module 50 passes through the optical recording medium 1 ), And the light reflected from the optical recording medium 1 is directed to the photodetector 80. The optical path changing means preferably employs a flat beam splitter 73 arranged obliquely on the optical path as shown. Further, a cubic beam splitter, a polarizing beam splitter, a hologram element, or the like may be employed.

Here, in the optical output module 50 on the optical path between the optical output module 50 and the flat beam splitter 73 so that the track error signal can be detected by the three-beam method through the optical detector 80. It is preferable to further include a grating 71 for diffraction-transmitting the irradiated light into a zeroth order beam, a ± first order beam, or the like.

In addition, on the path between the plate-shaped beam splitter 73 and the objective lens 77, a mirror 74 reflects incident light to change the path, and a collimating lens that focuses incident divergent light to become parallel light. Optical elements such as 75 may be further included.

The photodetector 80 is irradiated from the first and second light sources 61 and 63 and receives light incident through the optical recording medium 1 to detect an information signal and a servo signal.

Here, it is preferable that an astigmatism lens 79 is provided on the optical path between the flat beam splitter 73 and the photodetector 80 so as to detect the focus error signal by the astigmatism method. The astigmatism lens 79 is preferably disposed to be inclined on the optical path so that the aberration according to the inclined arrangement of the flat beam splitter 73 can be corrected.

As described above, the operation of the configured compatible optical pickup apparatus will be described.

When employing a relatively thin optical disk 1a such as a DVD as the optical recording medium 1, the light irradiated from the first light source 61 is used. That is, most of the light irradiated from the first light source 61 passes through the beam splitter 65 and is then diffracted into at least three beams in the grating 71. This diffracted light is reflected by the planar beam splitter 73 and the mirror 74 and directed to the objective lens 77 while being parallel light by the collimating lens 75. The objective lens 77 focuses the incident light onto the optical disk 1a having a relatively thin thickness. The light reflected by the optical disk 1a is directed to the flat beam splitter 73 via the objective lens 77, the collimating lens 75, and the mirror 74. This light passes through the flat beam splitter 73 and is then condensed to the photodetector 80 via the astigmatism lens 79. The photodetector 80 is attenuated by an information signal for an optical disk 1a having a relatively thin thickness from incident light, a track error signal from a beam diffracted by the grating 71, and an astigmatism lens 79. A focus error signal from a beam having a score difference is detected.

The light irradiated from the first light source 61 and reflected from the beam splitter 65 of the optical output module 50 is formed in the monitor photodetector 67, and the first light source 61 and the monitor are used. The light output of the first light source 61 is controlled through the light output control circuit between the photodetectors 67.

On the other hand, when the relatively thick optical disk 1b such as a CD is employed as the optical recording medium 1, the light irradiated from the second light source 63 is used. In this case, most of the light irradiated from the second light source 63 is reflected by the beam splitter 65 and directed toward the optical recording medium 1. Here, in contrast to the operation of the light irradiated from the first light source 61 described above, there is only a difference in that the light focused by the objective lens 77 is focused on a relatively thick optical disk 1b. Since it is the same, detailed description thereof will be omitted.

The light irradiated from the second light source 63 and transmitted through the beam splitter 65 is formed in the monitor photodetector 67, and the light between the second light source 63 and the monitor photodetector 67. The light output of the second light source 63 is controlled through an output control circuit.

The optical output module and the compatible optical pickup device employing the same according to the present invention configured as described above have the following advantages.

First, since the first and second light sources are in one optical module, the man-hour of assembling the optical pickup device is as simple as the optical pickup device for DVD or CD only.

Second, since one monitor photodetector is used for the plurality of wavelengths, wiring of the light output control circuit is simplified.

Third, since the monitor photodetector uses a portion of the effective output light of the first and second light sources, the rear light output of the first and second light sources is unnecessary. Therefore, the light output can be greatly increased by changing the structure of the light source.

Claims (8)

A base; First and second light sources disposed on the base and irradiating laser light of different wavelength regions; A beam splitter for splitting light emitted from the first and second light sources; And a light detector for monitoring the light output of the first and second light sources by receiving light emitted from the first and second light sources and branched in one direction from the beam splitter. module. The method of claim 1, A heat sink is further provided on the base, Each of the first and second light sources is provided on each of the side and the top surface of the heat sink. The method according to claim 1 or 2, An exit hole radiated from the first and second light sources and exited in a different direction from the beam splitter, and having an exit hole to surround the first and second light sources, the beam splitter, and a photodetector for a monitor; Light output module characterized in that it further comprises a cap installed on. The method of claim 3, The output hole of the cap is characterized in that the light output module is sealed by the beam splitter. A base, first and second light sources provided on the base to irradiate laser light of different wavelength regions, a beam splitter to branch light emitted from the first and second light sources, and the first and second light sources. An optical output module including a light detector for monitoring the light output of the first and second light sources by receiving light emitted from two light sources and branched in one direction from the beam splitter; An objective lens disposed on an optical path between the optical output module and a recording medium to focus light emitted from the first and second light sources onto the optical recording medium; Optical path converting means disposed on an optical path between the optical output module and the objective lens to convert a traveling path of incident light; And a photodetector configured to receive light incident through the optical path changing means after being irradiated from the first and second light sources and reflected from the optical recording medium. The method of claim 5, A heat sink is further provided on the base, And each of the first and second light sources is provided on each of side and top surfaces of the heat sink. The method according to claim 5 or 6, An exit hole radiated from the first and second light sources and exited in a different direction from the beam splitter, and having an exit hole to surround the first and second light sources, the beam splitter, and a photodetector for a monitor; Compatible optical pickup device further comprises a cap installed in. The method of claim 7, wherein The exit hole of the cap is sealed by the beam splitter.