KR100262963B1 - Optical pickup device - Google Patents

Abstract

PURPOSE: An optical pickup device is provided to reduce the number of components by using an optical flux path adjusting prism having a total reflection surface and an optical flux path adjusting unit. CONSTITUTION: A optical flux path adjusting prism(32) is located between first and second hologram modules(22,24), and an object lens(30). The prism converts path of an optical beam projected from the hologram modules to vertical direction. Moreover, the prism adjusts a linear flux path of the optical beam according to kind of an optical disk(36). An optical pickup device contains a collimating lens(28) located between the hologram modules and the prism, and a beam splitter(26) located between the hologram modules and the collimating lens. The beam splitter penetrates a first optical beam from the first hologram module while reflecting a second optical beam toward the object lens. The splitter penetrates or reflects the reflected optical beam to an optical detector of the first hologram module or the second hologram module.

Description

Optical pickup

The present invention relates to an optical pickup apparatus which reduces the number of parts of an optical system by using a beam mirror adjusting prism having a total reflection surface and a beam mirror adjusting unit.

Typically, an optical pickup device is used as an auxiliary memory device of a computer system by picking up information contained on an optical disk by a reflected light beam which is reflected by scanning a light beam onto the surface of the optical disk. As computer systems become smaller and lighter, optical pickup devices are becoming smaller and lighter, but due to structural problems, they cannot be made very thin below a certain limit, resulting in portable computers (eg, notebook personal computers and laptop-tops). (Lap-top) computer, etc.) was difficult to mount. This is because the optical pickup device for the optical pickup can reflect the light beam only at one angle (for example, at right angle) like the reflector, but the optical pickup device for the heterogeneous optical disc is used for its implementation. Dik) and CD (Compact Disk (hereinafter referred to as CD)) and the light source module for adjusting the light beam diameter according to the optical disk is required for the need. As a result, the conventional optical pickup apparatus has two positions to form a light beam path.

In the above places, the light beams had to be manufactured to change the direction of movement of the light beams. As a result, the conventional optical pickup apparatus could not be thinned below a certain limit.

An optical pickup apparatus according to the prior art will be described with reference to FIG. 1.

FIG. 1 is a view showing an optical pickup apparatus according to the prior art, and the optical pickup apparatus according to the prior art in the configuration of FIG. 1 includes a first hologram module 2 for generating a light beam having a first wavelength, and a second A second hologram module 4 for generating a light beam having a wavelength, an objective lens 10 for focusing the light beams from the first and second hologram modules 2, 4 on the recording surface of the optical disc 16; A rectangular prism 12 is disposed between the first and second hologram modules 2 and 4 and the objective lens 10 to change the path of the light beam. Each of the first and second hologram modules 2 and 4 has a hologram optical element (hereinafter referred to as a HOE) and has both a light source for generating a light beam and a photodetector for converting the amount of received light into an electrical signal. It is organized. That is, each of the first and second hologram modules 2 and 4 is packaged to simultaneously perform the functions of the light source and the photodetector. The first hologram module 2 generates a first light beam having a wavelength of 650 nm. The second hologram module 4 generates a second light beam having a wavelength of 780 nm. The first and second hologram modules 2 and 4 are selectively driven according to the type of the optical disc 16. On the other hand, the right prism 12 changes the path of the light beams irradiated from the first and second hologram modules 2 and 4 vertically so as to propagate toward the objective lens 10 and the light beam reflected by the optical disk 16. Is reflected toward the photodetectors in the first and second hologram modules 2 and 4.

In addition, the optical pickup device according to the related art includes a collimating lens 8 positioned between the objective lens 10 and the right angle prism 12, and the first and second hologram modules 2 and 4 and the right angle prism 12. A beam splitter 6 positioned therebetween and an optical shutter 14 positioned between the collimating lens 8 and the objective lens 10 to adjust the light beam mirror are further provided. The beam splitter 6 transmits the light beam from the light source of the first hologram module 2 while reflecting the light beam from the light source of the second hologram module 4 toward the objective lens 10. In addition, the beam splitter 6 is reflected by the optical disk 16 and transmits the reflected light beam through the objective lens 10 toward the photodetector of the first hologram module 2 or of the second hologram module 4. Reflect toward the photodetector. On the other hand, the collimating lens 8 causes the light beam from the beam splitter 6 to travel toward the objective lens 10 in parallel. The optical shutter 14 adjusts the beam diameter of the light beam according to the type of optical disk. In detail, when the optical disk is a CD, a light beam having a wavelength of 780 nm is allowed to pass through the light beam effective mirror 13 for the CD. At this time, the CD light beam effective mirror 13 can also pass a light beam of 650 nm. On the other hand, when the optical disc is a DVD, the light beam effective diameter 15 for the DVD passes through the 650 nm light beam.

However, the optical pickup device according to the prior art has a large number of parts constituting the optical pickup device, which takes a lot of time to assemble and adjust, it is pointed out as a problem that the thickness of the optical pickup is increased and it is difficult to thin. .

Accordingly, a first object of the present invention is to provide an optical pickup apparatus suitable for reducing the number of parts of an optical system by using a beam mirror adjusting prism having a total reflection surface and a beam mirror adjusting unit.

1 is a view showing an optical pickup apparatus according to the prior art.

2 is a view showing an optical pickup apparatus according to the present invention.

FIG. 3A is a detailed view of the second view beam control prism. FIG.

3b is a detailed view of one side of the beam mirror adjusting prism.

4 shows the spectral characteristics of the short wavelength transmission filter of FIG.

FIG. 5 is a view showing phase correction characteristics of the phase compensator of FIG. 3b.

* Explanation of symbols for the main parts of the drawings

2, 22: first hologram module 4, 24: second hologram module

6, 26: beam splitter 8, 28: collimation lens

10, 30: objective lens 12: right angle prism

14: optical shutter 16, 36: optical disk

32: beam mirror adjustment prism 38: beam mirror adjustment unit

40: total internal reflection surface 42: light beam effective diameter for DVD

44: light coating boundary 46: light beam effective diameter for CD

In order to achieve the above object, the optical pickup device of the present invention is located between the first and second light sources and the objective lens to vertically convert the path of the light beam irradiated from the first and second light sources, and to the type of optical disc. Accordingly, a beam diameter adjusting prism for adjusting the beam diameter of the light beam is provided.

Other objects and features of the present invention other than the above object will become apparent from the description of the embodiments with reference to the accompanying drawings.

A preferred embodiment of the present invention will be described with reference to FIGS. 2 to 5.

2 is a diagram illustrating an optical pickup apparatus according to an exemplary embodiment of the present invention. 2,

An optical pickup apparatus according to an embodiment of the present invention includes a first hologram module 22 for generating a light beam having a first wavelength, a second hologram module 24 for generating a light beam having a second wavelength, and a first and An objective lens 30 for focusing light beams from the second hologram modules 22 and 24 onto the recording surface of the optical disc 36;

And a beam diameter adjusting prism 32 positioned between the first and second hologram modules 22 and 24 and the objective lens 30. Each of the first and second hologram modules 22 and 24 has a HOE and includes a light source for generating a light beam and a photodetector for converting an amount of received light into an electrical signal. In other words, the first and second hologram modules 22 and 24 are packaged to simultaneously perform the functions of the light source and the photodetector. The light source of the first hologram module 22 generates a first light beam having a wavelength of 650 nm. The light source of the second hologram module 24 generates a second light beam having a wavelength of 780 nm. The first and second hologram modules 22 and 24 are selectively driven according to the type of the optical disc 36. The beam diameter adjusting prism 32 converts the paths of the light beams emitted from the first and second hologram modules 22 and 24 vertically, and adjusts the beam diameters of the light beams according to the type of the optical disc 36.

In addition, the optical pickup device according to an embodiment of the present invention is a collimating lens 28 positioned between the first and second hologram modules 22 and 24 and the beam diameter adjusting prism 32, and the first and second hologram modules. Further provided is a beam splitter 26 located between the 22 and 24 and the collimating lens 28. The beam splitter 26 transmits the first light beam from the first hologram module 22, while reflecting the second light beam from the second hologram module 24 toward the objective lens 30. In addition, the beam splitter 26 is reflected by the optical disk 36 to transmit the reflected light beam through the objective lens 30 toward the photodetector of the first hologram module 22 or the second hologram module 24. Reflect toward the photodetector. The collimating lens 28 causes the light beams from the beam splitter 26 to travel towards the objective lens 30 in parallel.

3A and 3B show in detail the light beam adjusting prism 32. Referring to FIG. 3A, the beam mirror adjusting prism 32 totally reflects the light beams internally so that the light beams are reflected at 90 °. Internal total reflection uses a phenomenon in which all of the light beams are reflected in a medium having a high refractive index when a light beam having an angle of incidence greater than a predetermined angle proceeds to a medium having a low refractive index in a medium having a high refractive index. The incident angle satisfying the internal total reflection condition is expressed by Equation 1.

[Equation 1]

Here, n1 is the refractive index of the air, n2 represents the refractive index of the beam diameter control prism material, and θ means the incident angle. For example, if n1 is air and n2 is BK7 glass, θ is calculated to be about 41 °. When this is described in connection with the optical pickup device, the light beam incident in parallel from the collimation lens 28 forms an incident angle of θ '= 45 + 1 ° in the total reflection surface 40 of the beam diameter adjusting prism 32. At this time, θ 'has a value larger than θ, and since the incident light beam is totally internally reflected at the total reflection surface 40 of the luminous flux adjusting prism 32, it is vertically reflected from the inside to be reflected vertically.

The path of the light beam is changed to the light beam control unit 38 at 32.

3B is a cross-sectional view of the light beam diameter adjusting portion 38 of FIG. 3A, and the light beam diameter adjusting portion 38 has a ring shape to adjust the light beam diameter on one vertical surface of the light beam diameter adjusting prism 32. FIG. A short wave pass filter (hereinafter referred to as SWPF) is formed in a predetermined region 42, and a phase compensating plate 44 is provided in the remaining region. The SWPF is formed by alternately depositing titanium oxide (TiO ₂ ) and silicon oxide (SiO ₂ ) to pass a specific wavelength according to its spectral characteristics. The spectral characteristics of this SWPF are shown in FIG. On the other hand, the phase compensator 44 grows silicon oxide (SiO ₂ ) to a desired thickness for phase correction, thereby allowing all light beams having wavelengths of 780 nm and 650 nm to pass through. The phase correction characteristic of the phase compensator at this time is shown in FIG. For example, a CD reproduction light beam using a wavelength of 780 nm does not pass through the SWPF but passes within the range of the CD light beam effective diameter 46 so that the aperture diameter becomes small, and a DVD reproduction light beam using a wavelength of 650 nm. Since can pass through SWPF, opening diameter becomes large. On the other hand, the CD light beam effective mirror 46 overlaps with the boundary of the actual SWPF, thereby securing even room for the flow of the objective lens by the tracking operation or the focusing operation of the actuator (not shown) to improve the performance of the optical system. It is to improve.

As described above, the ultra-thin optical pickup device of the present invention can reduce the number of parts of the optical system by using a beam diameter adjusting prism, thereby reducing the manufacturing cost and reducing the thickness of the optical pickup device.

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the technical spirit of the present invention. Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification but should be defined by the claims.

Claims (5)

A first light source for generating a light beam having a first wavelength, a second light source for generating a light beam having a second wavelength, and an objective lens for focusing the light beams generated from the first and second light sources on a recording surface of the optical disc. In the optical pickup device having, A luminous flux positioned between the first and second light sources and the objective lens to vertically convert a path of the light beam irradiated from the first and second light sources, and to adjust a beam diameter of the light beam according to the type of the optical disk; An optical pickup apparatus using a beam diameter adjusting prism, comprising a mirror adjusting prism. The method of claim 1, The beam mirror adjustment prism, A total reflection surface for vertically internally reflecting the light beams incident from the first and second light sources; And a light beam mirror adjusting unit for adjusting the light beam mirror of the light beam which is vertically changed in the total reflection surface. The method of claim 2, The total reflection surface, The optical pickup device using a beam mirror adjusting prism, characterized in that the total internal reflection of the light beam so that the incident angle and the material of the light beam incident on the first and second light sources to satisfy the total reflection condition. The method of claim 2, The beam diameter adjusting unit, A short wavelength transmission filter formed in a predetermined region of one side of the beam diameter adjusting prism and transmitting a short wavelength; And a phase compensating plate disposed in the remaining region except for a predetermined region of one side of the beam diameter adjusting prism. The method of claim 4, wherein The short wavelength transmission filter, An optical pickup apparatus using a beam diameter adjusting prism, formed by alternately depositing titanium oxide (TiO 2) and silicon oxide (SiO 2) to transmit a light beam having a specific wavelength according to its spectral characteristics.

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