KR980011138A - Optical pick-up device - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical pick-up apparatus for simultaneously reproducing a digital audio disc (DAD) for general music reproduction and a digital video disc (DVD) for video and audio reproduction.

A surface-emission laser diode formed inside one side of the silicon substrate and emitting a laser beam of a predetermined wavelength; a support formed on the other side of the silicon substrate; A photodetector for converting the optical information of the disk into a current, a prism for forming a predetermined size on the silicon substrate on which the surface-emission laser diode is formed and transmitting the laser beam, a prism for guiding the laser beam in a diagonal direction inside the prism, A hologram grating formed on one side of the prism for focusing a beam reflected from the beam splitter and returning to the photodetector, a hologram grating for irradiating the beam onto the photodetector, A spot that can be adjusted to the size of a spot on a disc by being formed as a light part. It is made of Izu control panel.

Description

The optical pickup device

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical pick-up apparatus for recording a signal on an optical data recording medium and reproducing the recorded information as an electric signal, And a video disk (DVD) can be played back at the same time.

2. Description of the Related Art In general, an optical pick-up apparatus for reproducing electric signals from information recorded on a digital audio disk (DAD) or a digital video disk (DVD) is provided with individual components such as an objective lens, a beam splitter, a diffraction grating, a laser diode, .

That is, as shown in FIG. 1, a structure of an OPTICAL-PICK-UP apparatus used in a digital audio disk generally includes a laser diode 51 for emitting a laser beam, And diffraction gratings 52 for separating light into light for focus and tracking error detection are provided at predetermined intervals.

A beam splitter 53 is disposed on one side of the diffraction grating 52 and has a predetermined slope so as to separate the incident light into the reflected light and the transmitted light having a constant reflectance and transmittance.

An objective lens 54 having a diffraction limit performance of a predetermined wavelength or less and condensing the separated light to focus information on the disk 55 and reading information recorded thereon is disposed at a predetermined interval on the beam splitter 53 And a photodetector 56 for converting the optical information recorded on the audio and video disk 55 into an electric current through an objective lens 54 at a lower portion of the beam splitter 53 is installed at a predetermined interval .

In the conventional optical pick-up apparatus having such a structure, first, a laser beam having a predetermined oscillation wavelength is emitted from the laser diode 51. As the laser beam passes through the diffraction grating 52, the focus and tracking error Three beams for detection (THREE BEAM: zero-order light and ± one-order light) are separated and emitted.

Therefore, the light separated by the diffraction grating 52 is emitted to the beam splitter 53 having a constant reflectance and transmittance, thereby separating the incident light into the reflected light and the transmitted light, and the reflected light is transmitted to the objective lens 54 The beam is focused on the audio or video disk 55 to focus on the disk 55 and read the information recorded on the disk 55. [

In other words, the objective lens 54 condenses light onto the signal surface of the disk 55 in the form of air having a size of several micrometers. The light is returned almost as it is without the pit 55a on which the data is recorded, The light is diffracted by the pit 55a and is emitted outside the range of the objective lens 54. As a result, only a part of the incident light is returned, thereby causing a light amount difference in the photodetector 56. [

On the other hand, the intensity of the light reflected from the audio or video disk 55 is modulated by the pit 55a, and the modulated light information is transmitted through the objective lens 54 and the beam splitter 53 to the photodetector 56 To convert the optical information into a current and demodulate the converted current into an original signal by a digital signal processing unit (not shown) to reproduce the audio signal recorded on the disk 55. [

Such a conventional optical pick-up apparatus reads only information recorded on one of a digital audio disk (DAD) and a digital video disk (DVD), and can not selectively read data recorded on two kinds of disks do.

The reason is that the data recording capacity of the digital video disk is four times as large as that of the digital audio disk, and the width of the pit is reduced to about half that of the digital audio disk, so that the spot size is also small Should be formed.

That is, when the spot size in the digital audio disk is 1.6 mu m in diameter and the spot size in the digital video disk is 0.8 mu m in diameter, audio and video data recorded on the disk can be accurately reproduced.

Therefore, since the conventional optical pick-up apparatus shown in FIG. 1 can form a spot size of only one of the diameter of 1.6 μm and the diameter of 0.8 μm, it is possible to selectively reproduce audio and digital video disks having different data recording systems There is no problem.

The present invention relates to a surface-emitting laser diode which emits two different wavelengths to a silicon substrate, a beam splitter which reflects and transmits at a predetermined ratio of incident beam to the prism, a combinatorial beam portion which reflects the entire amount of the laser beam, And a hologram grating for converging the optical information returned through the disc and irradiating the optical information onto the photodetector, so that a laser beam of a specific wavelength is reflected on the spot size regulating plate A beam focus of 1.6 μm and 0.8 μm in diameter is formed on the disc at the same time so that it is possible to reproduce a digital video disc having a significantly narrower pit width due to a large number of data recording capacity than that of the audio disc Thereby contributing to the improvement of the reliability of the optical pick-up apparatus The present invention has the object of the present invention.

That is, the present invention provides a semiconductor device comprising: a silicon substrate on which a plurality of optical elements are placed; a surface-emission laser diode formed inside one side of the silicon substrate to emit a laser beam of a predetermined wavelength; a support formed on the other side of the silicon substrate; A photodetector formed at a predetermined position to convert the optical information of the disk into a current, a prism that is formed in a predetermined size on a silicon substrate on which the surface-emission laser diode is formed and transmits a laser beam, A hologram grating formed on one side of the prism for focusing the beam reflected from the beam splitter and returning to the photodetector, a hologram grating for reflecting the incident beam at a predetermined ratio, Spots that can be adjusted to the size of the spot on the disc by being formed as a light part and a combat light part It has been made to rise throttle.

FIG. 1 is a block diagram of a conventional optical pick-up apparatus. FIG.

FIG. 2 is a configuration diagram of an optical pick-up apparatus according to the present invention; FIG.

DESCRIPTION OF THE REFERENCE NUMERALS

54: objective lens 55: disk

60: silicon substrate 61: support

62: photodetector 63: surface-emission laser diode

64: diffraction grating 65: beam splitter

66: prism 67: holographic grating

68: Transmuter 69: Combat Miner

70: Spot size adjustment plate

Fig. 2 is a configuration diagram of the optical pick-up apparatus according to the present invention. A surface-emission laser diode 63 for emitting a laser beam of a predetermined wavelength is formed on one upper surface of a silicon substrate 60, A prism 66 for transmitting a laser beam is formed in a predetermined size on the upper portion of the silicon substrate 60 on which the laser beam 63 is formed.

Here, the surface-emission laser diode 63 uses a space-emission type laser diode in which a laser beam is emitted upward by P / N bonding.

A beam splitter 65 for reflecting and transmitting the laser beam emitted from the surface-emission laser diode 63 at a predetermined ratio is formed in a diagonal direction at a central portion of the prism 66, A hologram grating 67 is formed which focuses the returning light reflected from the light source 55 and irradiates the light to the photodetector 62.

The prism 66 has a comb-shaped portion 69 for transmitting the entire incident beam and a semi-transparent portion 68 for reflecting and transmitting the incident beam at a predetermined ratio, There is formed a spot size regulating plate 70 whose size can be adjusted.

A support body 61 on which a photodetector 62 for detecting optical information of the disk 55 is integrally formed is formed on the other side of the silicon substrate 60. An upper side of the spot size regulating plate 70 And an objective lens 54 that focuses the incident beam and forms a beam focus on the disk 55 is provided.

In the present invention as described above, a surface-emission laser diode 63 of a surface emission type in which a laser beam is emitted upward by a P / N junction is formed at a central portion of one side of a silicon substrate 60, And the laser beam is irradiated to a beam splitter 65 formed in the prism 66 to reflect and transmit the incident beam at a predetermined ratio.

At this time, as the laser beam transmitted through the beam splitter 65 is irradiated on the spot size regulating plate 70, two kinds of beam paths are formed. The spot size is formed differently according to the beam path, DAD) or a digital video disc (DVD).

That is, the laser beam reflected through the beam splitter 65 is half-reflected by the semi-transparent portion 68 of the spot size regulating plate 70, and the other half is transmitted, and the transmitted beam passes through the objective lens 54 The light beam is converged at an angle of &thetas; 1 to form a beam focus on the disk 55. [

At the same time, the laser beam reflected by the beam splitter 65 is totally transmitted by the comb-shaped beam portion 69 of the spot size regulating plate 70 and is irradiated on the objective lens 54, The beam focus is formed on the disk 55 at an angle of &thetas;

Therefore, the first and second numerical apertures NA1 and NA2 are divided by the comb-shaped portion 69 and the translucent portion 68 of the spot-size regulating plate 70, The size of the beam formed on the disk 55 is changed, resulting in a difference in the amount of light.

Here, the numerical expression of the numerical aperture is as follows.

NA1 =? Sin? 1 (1)

, And NA2 =? Sin? 2.

(Where eta is the refractive index and eta in the air is 1.)

NA1 = Sin? 1 (2)

, And NA2 = Sin &thetas; 2.

D = K x lambda / NA, H = R x lambda / (NA) ² (3)

(Where D is the beam size, H is the depth of focus, and K and R are constants, respectively, the beam size and depth of focus change as the NA changes.

Therefore, the beam size and the depth of focus, which are transmitted through the translucent portion 68 of the spot size regulating plate 70 and converged at the angle of? 1, are smaller than the beam size and depth of focus converged at the angle of? 2 through the comb- (Because the beam size is inversely proportional to NA and the depth of focus is inversely proportional to (NA) ² )

Therefore, the laser beam that has been transmitted through the translucent portion 68 of the spot size regulating plate 70 and converged by the objective lens 54 at the angle of? 1 is formed on the disk 55 with a beam spot having a size of 1.6 mu m, 55a of the spot size regulating plate 70 and transmitted through the combed light portion 69 of the spot size regulating plate 70 and is converged by the objective lens 54 at the angle of? The beam is formed with a beam spot having a size of 0.8 mu m on the disk 55, thereby reading the recorded data on the digital video disk (DVD) having a narrower length of the pit 55a.

That is, the light is condensed in the airy form of 1.6 mu m and 0.8 mu m converged at the angles of [theta] 1 and [theta] 2 by the combinational light portion 68 and the translucent portion 69 and the objective lens 54 of the spot size regulating plate 70, Or the signal surface of the digital audio disk 55. This light is returned almost as it is in the absence of the pit 55a in which the data is recorded but in the place where the pit 55a is located, Diffracted by the objective lens 54 and emitted out of the range of the objective lens 54. As a result, only a part of the incident light is returned, resulting in a light amount difference in the photodetector.

Assuming that the disc 55 is a digital audio disc in this state, the optical information of the digital audio disc, which is converged at the angle of? 1, returns again to the angle? 1 by the objective lens 54 and the spot size regulating plate 70 And is irradiated to the beam split 65 via the translucent portion 68.

Therefore, the beam splitter 65 reflects and transmits the optical information returned through the disk 55 at a predetermined ratio, and the reflected beam is irradiated with the hologram grating 67 formed on one side of the prism 66 And is converged by the photodetector 62 formed on the support 61.

On the other hand, assuming that the disk 55 is a digital audio disk, the optical information of the digital audio disk, which is converged at the angle of 2, is again incident on the objective lens 54 and the comb- Is irradiated to the beam splitter (65) via the beam splitter (69).

Therefore, as described above, the beam splitter 65 reflects and transmits the light information coming back through the disk 55 at a constant rate, and the reflected beam passes through the holographic grating (not shown) formed on one side of the prism 66 67, and is converged by the photodetector 62 formed on the support 61.

The photodetector 62 converts the optical information of the disk into a current and outputs an RF signal, a focus signal, and an RF signal by a digital signal processing unit (not shown) The audio signal recorded on the digital audio and video disc is reproduced by detecting and demodulating the tracking signal into the original signal.

In the structure of the present invention, focus error detection is detected by a Foucault method, and tracking error detection is detected by a push-pull method by a one-beam method.

A surface emitting laser diode, a prism, a beam splitter, a spot size regulating plate, a photodetector, and a hologram grating are integrated on a silicon substrate so that when a laser beam of a specific wavelength passes through the spot size regulating plate, and a beam focus of 0.8 mu m can be formed at the same time, so that it is possible to reproduce a digital video disk in which the data recording capacity is several times larger than that of the digital audio disk and the pit width is remarkably narrower than that of the audio disk, It is possible to contribute to improvement.

Claims (1)

A optical pick-up apparatus for condensing a beam with a laser beam as an objective lens to record a signal on a disk and reproduce the recorded information as an electric signal, comprising: a silicon substrate (60) on which a plurality of optical elements A surface emitting laser diode 63 formed inside one side of the silicon substrate 60 and emitting a laser beam of a predetermined wavelength, a support 61 formed on the other side of the silicon substrate 60, A photodetector 62 formed on the silicon substrate 60 to convert the optical information of the disk into a current and a prism 66 formed to a predetermined size on the silicon substrate 60 on which the surface-emission laser diode 63 is formed, A beam splitter 65 formed diagonally inside the prism 66 to reflect and transmit the incident beam at a predetermined ratio, a beam splitter 65 formed on one side of the prism 66, Reflected from A hologram grating 67 that focuses the beam and irradiates the beam onto the photodetector 62, and a translucent portion 68 and a comb transparent portion 69 on the upper surface of the prism 66, And a spot size regulating plate (70). ※ Note: It is disclosed by the contents of the first application.