KR20050116266A - Optical pick-up apparatus for controlling beam spot - Google Patents

Abstract

The present invention is to provide an optical pickup device that can reduce the manufacturing cost and minimize the components of the product by using only one two-wavelength light source when detecting the optical signal for optical recording or playback on a CD or DVD, Light generation processing means for generating a two-wavelength laser beam for data recording or reproduction and scanning by approximating a focal length of the laser beam; Beam deformation and scanning means for focusing the beam emitted from the light generation processing means onto the optical disc, diverting and condensing the beam shape of a specific wavelength to scan the optical disc, and scanning the beam reflected from the optical disc in the direction of the photodetector; And a scanning process that reflects the beam scanned from the light generating processing means and scans the beam into the beam deformation and scanning means, and modifies and scans the shape and size of the reflected beam of the optical disc scanned through the beam deformation and scanning means to suit the photodetector. Means;

Description

Optical pick-up apparatus for controlling beam spot

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical pickup apparatus, and more particularly, to an optical pickup apparatus capable of performing optical recording and reproduction using only one two wavelength light source when detecting an optical signal for optical recording or reproduction on a CD or DVD.

In general, in an optical pickup apparatus that reads or records information on a recording medium such as a CD-RW (CD-Rewritable Compact Disc), a predetermined optical recording medium in which information is collected from a light source such as a laser diode, that is, an optical disc. An optical receiver is used as a photodetecting device (PDIC) that projects light onto a back plate, detects light reflected from the back, and converts the light into an electrical signal.

In a CD capable of recording such as a CD-RW, a write operation is performed by forming a pit on the surface of the CD by scanning the surface of the CD with a laser light source having a strong power.

In recent years, with the development of the DVD recorder market, the importance of the optical pickup device used for DVD-RW has been highlighted.

Such a conventional optical pickup apparatus will be described with reference to FIG. 1.

1 schematically shows a configuration of an optical pickup apparatus using a conventional short wavelength light source.

As shown in FIG. 1, a conventional optical pickup apparatus includes a first laser diode (LD) 101 for generating a LD laser beam and a second laser diode (LD) 102 for generating a DVD laser beam. ), A first diffraction grating 103 for diversifying the laser beam generated from the first laser diode 101, and a second diffraction grating for diversifying the laser beam generated from the second laser diode 102. (104), a coupling lens (105) to approximate the focal length of the beam, a cubic (106) for transmitting and reflecting the incident beam, and the incident beam deforms the balanced light A collimation lens 107, a reflector 108 for reflecting the incident beam, an objective lens 109 for focusing the incident beam, and an optical disk for recording and reproducing optical data. 110 and a flat beam splitter for reflecting or transmitting an incident beam ( PBS: Plat Beam Splitter (111), a photodetector (PDIC) 112 for receiving beams reflected by the optical disk 110, and a shape and size of beam spots scanned by the photodetector 112 are determined. A sensor lens 113 is provided.

The first laser diode 101 generates a short wavelength laser beam for recording data in the LD or reproducing the data recorded in the LD, and generates a beam having a short wavelength for LD to scan the first diffraction grating 103.

The second laser diode 102 generates a laser beam for recording data on the DVD or reproducing the data recorded on the DVD, but generates a beam having a short wavelength for the DVD to scan the second diffraction grating 104.

The first diffraction grating 103 multiplies the short wavelength laser beam generated from the first laser diode 101 and scans it into the coupling lens 105. At this time, the first diffraction grating 103 scans the incident short wavelength beam by the 0th order diffraction, + 1st order diffraction, and -1st order diffraction to the coupling lens 105.

The second diffraction grating 104 multiplies the short wavelength laser beam generated from the second laser diode 102 and scans it into the flat beam splitter 111. At this time, the second diffraction grating 104 scans the incident short-wavelength beam by the zero-order diffraction, + first-order diffraction, and -first-order diffraction, into the flat beam splitter 111.

The coupling lens 105 is for improving beam coupling efficiency and approximates the beam focal length between the first laser diode 101 and the balanced light lens 107. This is because when the first laser diode 101 and the balanced light lens 107 are spaced apart by a predetermined distance or more, the focus of the laser beam generated from the first laser diode 101 becomes inaccurate. ) Improves this.

The cubic 106 transmits the beam scanned through the coupling lens 105 to the balanced light lens 107 and reflects the beam reflected by the flat beam splitter 111 to the balanced light lens 107. Inject.

When the beams generated from the first and second laser diodes 101 and 102 are scanned onto the optical disc 110, the optical disc 110 reflects the incident beam. When the reflected beam is scanned to the cubic 106 through the balanced light lens 107, the cubic 106 reflects the beam and scans the flat beam splitter 111.

The balanced light lens 107 transforms the beam incident from the cubic 106 into the balanced light, scans the reflected beam 108, and transforms the beam reflected by the reflector 108 into the balanced light, into the cubic 106. Inject.

The reflector 108 reflects the beam scanned through the balanced light lens 107 to scan the objective lens 107 and reflects the incident beam reflected by the optical disk 110 in the direction of the balanced light lens 107.

The objective lens 109 focuses a beam scanned through the reflector 108 to scan the optical disk 110 and focuses a beam reflected by the optical disk 110 to scan the reflector 108.

The optical disc 110 may be implemented as a CD or a DVD.

The flat beam splitter 111 reflects the diffracted beam multiplied by the second diffraction grating 104 and scans it into the cubic 106 and transmits the beam reflected and reflected by the cubic 106 to the sensor lens 113. Injection).

The sensor lens 113 scans the photodetector 112 by determining the shape and size of the beam scanned through the flat beam splitter 111, but having a shape and size suitable for receiving the photodetector 112. Inject spot.

The photodetector 112 is implemented as a single chip, and includes a plurality of photodiodes arranged in a predetermined form. These photodiodes convert the beams received through the sensor lens 113 into electrical signals.

However, in the conventional optical pickup apparatus as described above, by using two laser diodes and providing a plurality of lenses, there is a problem that the manufacturing cost of the product is increased and the internal configuration is complicated.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an optical pickup apparatus capable of performing optical recording and reproduction using only one two wavelength light source when detecting an optical signal for optical recording or reproduction on a CD or DVD. The purpose is to provide.

One object of the present invention is to provide an optical pickup apparatus capable of adjusting the size of a beam spot when detecting an optical signal for optical recording or reproduction on a CD or DVD using a two-wavelength light source.

SUMMARY OF THE INVENTION An object of the present invention is to provide an optical pickup apparatus that can reduce manufacturing cost and minimize components of a product by using only one two wavelength light source when detecting an optical signal for optical recording or reproduction on a CD or DVD.

The present invention for achieving the above object comprises: light generation processing means for generating a two-wavelength laser beam for recording or reproducing data on an optical disc and scanning by approximating a focal length of the laser beam; Beam deflection and scanning for focusing the beam emitted from the light generation processing means to the optical disk, diverging and condensing the beam shape of a specific wavelength to the optical disk, and scanning the beam reflected from the optical disk in the direction of the photodetector Way; And reflect the beam scanned from the light generation processing means to scan the beam deformation and scanning means, and modify the shape and size of the reflected beam of the optical disk scanned through the beam deformation and scanning means to suit the photodetector. And scanning processing means for scanning by injection.

In general, in a two-wavelength laser diode, a laser beam of a DVD or a CD passes through the same optical system, and such combo optical pickup records data on a CD and reproduces data on a DVD. In such an optical system, it is a general aspect that the optical magnification differs. When the optical pickup records data on the CD, the coupling efficiency must be set large because a large amount of laser power needs to be output from the objective lens in order to perform recording. In addition, when the optical pickup reproduces data recorded on a DVD, the size of the beam spot must be taken into account because the density of the pit recorded on the DVD is high, and thus the optical magnification is set large.

As described above, since optical magnification is different when recording on CD and when playing DVD, two problems arise when designing a combo optical pickup using a two-wavelength laser. For example, when the optical system is designed for CD recording, The beam spot size of the DVD increases, and the optical output of the CD becomes inadequate when the optical system is designed for the DVD.

Therefore, the present invention is to improve the problem that the beam spot size of the DVD increases when the optical system is designed for CD recording, and for this purpose, a beam filter is used to pass the CD beam as it is and to diversify the shape of the DVD beam. have. That is, in the present invention, since the optical system is designed for CD recording, the rim intensity is low and the spot size is increased even during DVD playback. However, the beam filter is used to lower the transmittance of the central portion of the DVD laser beam. The beam spot is adjusted by creating an equivalent state with high intensity.

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

2 is a block diagram of an optical pickup apparatus for adjusting a beam spot according to an embodiment of the present invention.

Referring to FIG. 2, the optical pickup apparatus of the present invention includes a light generation processing unit 220 for generating a two-wavelength laser beam for recording or reproducing data of an optical disc 210 and scanning by approximating a focal length of the laser beam. The beam emitted from the light generation processing unit 210 is focused on the optical disc 210, the beam shape having a specific wavelength is diversified and collected to be scanned onto the optical disc 210, and the beam reflected from the optical disc 210 is detected by the photodetector. Beam deformation and scanning unit 240 to scan in the direction (230), and the beam is scanned from the light generation processing unit 220 is reflected in the beam deformation and scanning unit 240, the beam deformation and scanning unit 240 The shape and size of the reflection beam of the optical disk 210 to be scanned through the scanning detector 250 for modifying and scanning to suit the photodetector 230 is provided.

The light generation processor 220 passes the laser diode 221 for generating the two-wavelength laser beam and the two-wavelength laser beam for the CD generated from the laser diode 221 or is generated from the laser diode 221. The diffraction grating 222 which scans by dividing the 2 wavelength laser beam for DVD, and the coupling lens 223 which scans by approximating the focal length of the beam scanned through the diffraction grating 222 in order to improve the beam coupling efficiency. ).

The laser diode 211 consists of two chips, one of which generates a CD laser beam and the other of which generates a laser beam for a DVD. At this time, the laser diode 211 generates a CD laser beam or a DVD laser beam according to a beam generation control signal input from the outside.

Here, the laser diode 211 outputs laser light having a wavelength of 650 nm and a wavelength of 780 nm. Depending on whether laser light having these wavelengths is located on the same optical axis, the number and arrangement of photodiodes fixed on photodetector 230 may vary.

When the CD wavelength laser beam is incident from the laser diode 221, the diffraction grating 222 passes the beam as it is and scans the coupling lens 223. Upon incidence, the beam is diversified and scanned by the coupling lens 223. At this time, the diffraction grating 103 scans the incident two-wavelength laser beam for DVD by 0th diffraction, + 1st diffraction, and -1st diffraction to scan the diffracted diffracted beam into the coupling lens 105.

The coupling lens 223 improves beam coupling efficiency and approximates a beam focal length between the laser diode 221 and the beam deformation and the lens of the scanning unit 240. This is because when the lens of the laser diode 221 and the beam deformation and the scanning unit 240 are spaced apart by a predetermined distance or more, the focus of the laser beam generated from the laser diode 221 becomes inaccurate. ) Improves this.

The beam deformation and scanning unit 250 scans an incident beam through a balanced light lens 241 and a balanced light lens 241 for deforming the balanced light to scan the optical disk 210 or the photodetector 230. Reflector 242 for reflecting the beam toward the optical disk 210 or reflecting the beam reflected by the optical disk 210 to the balanced light lens 241, and the CD beam reflected by the reflector 242 as it is. A beam filter 243 that scans the size of the beam spot for DVD passing through or reflected through the reflector 242 to suit the optical disk 210 or scans the beam reflected by the optical disk 210 to the reflector 242. And an objective lens 244 for focusing a beam incident through the beam filter 243 to scan the optical disk 210 or for focusing a beam reflected from the optical disk 210 to the beam filter 243. .

When the beam passing through the coupling lens 223 is reflected by the scanning processing unit 250 and scanned, the balanced light lens 241 transforms the beam into balanced light and scans it with the reflector 242 or reflects from the optical disk 210. When the beam is incident through the reflector 242, the beam is transformed into balanced light and scanned by the scanning processor 250.

The reflector 242 reflects the beam scanned through the balanced light lens 241 and scans it with the beam filter 243, or if the beam reflected from the optical disk 210 is incident through the beam filter 243, the beam is balanced. Reflected by the lens 241.

When the beam for CD reflected by the reflector 242 is incident, the beam filter 243 scans the beam for the objective lens 244 by passing the beam as it is, and when the beam for DVD reflected by the reflector 242 is incident, The size of the beam is made to a size suitable for the optical disk 210 and scanned with the objective lens 244. When the beam reflected from the optical disk 210 is incident through the objective lens 244, the beam filter 243 focuses the beam and scans the beam to the beam filter 243.

A cross section of the beam filter 243 that performs this function is shown in FIG. 3.

The shape of the beam output by the beam filter 243 will be described with reference to FIGS. 4A and 4B.

Figure 4a is an exemplary view showing the light amount distribution form of the beam for CD passing through the beam filter applied to the present invention.

As shown in FIG. 4A, the CD beam generated from the laser diode 221 has a Gaussian shape, and since the beam passes through the beam filter 243 as it is, the beam passing through the beam filter 243 is also used. It also has the same shape as in the figure.

Figure 4b is an exemplary view showing the light amount distribution form of the beam for DVD passing through the beam filter applied to the present invention.

As shown in Fig. 4B, the beam for DVD generated from the laser diode 221 has a shape such as B1. However, when this beam is filtered by the beam filter 243, it is transformed into a shape like B2. When the beam shape is determined as B2 by the beam filter 243, only the center portion B3 forms a spot on the optical disk 210 among the beams of the B2 shape.

The objective lens 244 focuses the beam scanned from the beam filter 243 and scans the optical disk 210, or focuses the beam reflected by the optical disk 210 and scans the beam filter 243.

The scanning processor 250 reflects the beam scanned from the light generating processor 220 to the beam deformation and scanning unit 240, or reflects the reflected beam of the optical disc 210 incident through the beam deformation and scanning unit 240. And a sensor lens 252 for modifying and scanning the size and shape of the beam transmitted through the flat splitter 251 to suit the photodetector 230.

When the beam is scanned through the coupling lens 223, the flat beam splitter 251 reflects the beam to the balanced light lens 241, and the beam reflected by the optical disk 210 causes the balanced light lens 241 to be reflected. When incident through the beam, the beam is transmitted and scanned by the sensor lens 251.

The sensor lens 252 makes the shape and size of the beam scanned through the flat beam splitter 251 suitable for receiving the photodetector 230 and scans the photodetector 230.

Meanwhile, the optical disc 210 may be implemented as a CD or a DVD.

The photodetector 230 is implemented as a single chip, and includes a plurality of photodiodes arranged in a predetermined form. These photodiodes convert the beams received through the sensor lens 252 into electrical signals.

DVD photodiodes and CD photodiodes are separately disposed in the photodetector 230.

Although the technical spirit of the present invention has been described in detail according to the above-described preferred embodiment, it should be noted that the above-described embodiment is for the purpose of description and not of limitation. In addition, those skilled in the art will understand that various embodiments are possible within the scope of the technical idea of the present invention.

As described above, the present invention provides an optical pickup apparatus capable of reducing manufacturing costs and minimizing components of a product by using only one wavelength light source when detecting an optical signal for optical recording or reproduction on a CD or DVD. The purpose is to provide.

1 is a block diagram of an optical pickup apparatus using a conventional short wavelength light source.

2 is a block diagram of an optical pickup apparatus for adjusting a beam spot according to an embodiment of the present invention.

3 is a cross-sectional view of the beam filter applied to the present invention.

Figure 4a is an exemplary view showing the light amount distribution form of the beam for the CD passed through the beam filter applied to the present invention.

Figure 4b is an exemplary view showing the light amount distribution form of the beam for DVD passing through the beam filter applied to the present invention.

Explanation of symbols on the main parts of the drawings

210: optical disk 220: light generation processing unit

221: laser diode 222: diffraction grating

223: coupling lens 230: photodetector

240: beam modification and scanning unit 241: balanced light lens

242: reflector 243: beam filter

244: objective lens 250: scanning processing unit

251 flat beam filter 252 sensor lens

Claims (4)

Light generation processing means for generating a two-wavelength laser beam for recording or reproducing data on the optical disc and scanning by approximating a focal length of the laser beam; Beam deflection and scanning for focusing the beam emitted from the light generation processing means to the optical disk, diverging and condensing the beam shape of a specific wavelength to the optical disk, and scanning the beam reflected from the optical disk in the direction of the photodetector Way; And Reflects the beam scanned from the light generation processing means and scans the beam into the beam deformation and scanning means, and deforms the shape and size of the reflected beam of the optical disk scanned through the beam deformation and scanning means to suit the photodetector Injection processing means Optical pickup device comprising a. The method of claim 1, The light generation processing means, A laser diode for generating a two wavelength laser beam; A diffraction grating configured to pass the two-wavelength laser beam for CD generated from the laser diode as it is or to diversify and scan the two-wavelength laser beam for DVD generated from the laser diode; And Coupling lens scanning by approximating the focal length of the beam scanned through the diffraction grating to improve the beam coupling efficiency Optical pickup device comprising a. The method of claim 1, The beam deformation and scanning means, A balanced light lens configured to scan the incident beam into the optical disk or the photodetector by deforming the balanced light; A reflector reflecting a beam scanned through the balanced light lens toward the optical disk or reflecting a beam reflected by the optical disk to the balanced light lens; A beam which passes through the CD beam reflected by the reflector as it is or is modified by scanning the size of the DVD beam spot incident through the reflector as appropriate for the optical disk or scans the beam reflected by the optical disk to the reflector filter; And An objective lens for focusing a beam incident through the beam filter to scan the optical disk or focusing a beam reflected from the optical disk to scan the beam filter Optical pickup device comprising a. The method according to any one of claims 1 to 3, The scanning processing means, A flat splitter for reflecting the beam scanned from the light generation processing means to the beam deformation and scanning means or transmitting the reflected beam of the optical disk incident through the beam deformation and scanning means; And Sensor lens for scanning by modifying the size and shape of the beam transmitted through the flat splitter 251 to suit the photodetector Optical pickup device comprising a.