KR100586098B1 - Apparatus for optical pick-up - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical pickup apparatus for reproducing or recording an optical disk, and more particularly, to an optical monitor having an improved front monitor photo detector (MPD) structure for accurate intensity measurement and height reduction of a beam emitted from a laser diode. It relates to a pickup device.

An optical pickup apparatus according to the present invention comprises a laser diode for generating a laser for recording or reproducing information, a photo detector for reading a beam reflected from an optical disk, a beam splitter for beam separation, and An optical pickup device comprising an objective lens for collecting at an accurate point and a monitor photo detector for measuring beam intensity emitted from the laser diode, the monitor photo detector comprising: a PC, an electrode formed on a side of the PC; The transparent layer on the upper side of the PC, and the monitor photo detector cell located on the upper side of the PC, characterized in that it is included.

Optical pickup, MPD

Description

Optical pickup device {APPARATUS FOR OPTICAL PICK-UP}

1 is a view for explaining a method of taking a part of a beam emitted from a laser diode in a conventional optical pickup apparatus.

2 is a view for explaining another method of taking a part of a beam emitted from a laser diode in the optical pickup device.

3 is a view for explaining an example of a conventional MPD.

4 is a view for explaining a method of tilting the MPD installation.

5 is a perspective view of an MPD of the optical pickup apparatus according to the present invention.

6 is a view for explaining an example where an MPD is installed.

<Explanation of symbols for main parts of drawing>

10; Laser diode 20; Beam splitter

30; MPD 31; PD Cell

32; PCB 33; electrode

40; Collimator lens 60; MPD

61; PD Cell 62; PCB

63; Electrode 64; Transparent layer

65; Opaque layer

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical pickup apparatus for reproducing or recording an optical disk, and more particularly, to an optical monitor having an improved front monitor photo detector (MPD) structure for accurate intensity measurement and height reduction of a beam emitted from a laser diode. It relates to a pickup device.

An optical disc is a product that records and reproduces information by using optical characteristics, and generally has a small disc shape. In order to use an optical disc, an optical disc driver is required, and information of the optical disc is reproduced or recorded by an optical pickup device mounted inside the optical disc driver.

This optical pickup is important for a laser diode (LD) that generates a laser, a photo detector (PD) for reading a beam reflected on an optical disk, and a beam splitter for separating the beam. Used as a part.

On the other hand, a mechanism called an actuator (actuator) is used to accurately form a beam on the optical disk, the actuator moves the position of the objective lens that collects the laser from the laser diode to the exact point where the information on the optical disk is recorded by the laser It is a device for improving the performance of reproducing and recording information.

In this process, the intensity of the beam emitted from the laser diode should be adjusted appropriately due to the state of the laser diode and the write strategy. To do this, it is necessary to measure the exact intensity of the beam, which is used as a monitor photo detector (hereinafter referred to as MPD).

Since the MPD is intended to measure the intensity of the beam emitted from the laser diode, the MPD is installed between the laser diode or the object lens and takes a portion of the emitted beam to measure the total beam intensity emitted from the laser diode.

Therefore, the MPD has a sufficient SN ratio even for a small amount of light, so that an accurate signal must be generated despite the noise, and the signal must not be saturated even at the maximum amount of light.

1 is a view for explaining a method of taking a part of a beam emitted from a laser diode in a conventional optical pickup device.

As shown in FIG. 1, the beam emitted from the laser diode 10 is sent to the objective lens through the beam splitter 20 and the collimator lens 40, wherein the beam is split using the beam splitter 20. Part of is sent to the MPD (30). In this case, the amount of beam sent to the MPD 30 is determined according to the reflective film characteristic of the beam splitter 20, and the intensity of the beam emitted from the laser diode 10 is measured according to the amount of the corresponding beam.

However, the method used in FIG. 1 has a problem that the beam reflected from the MPD 30 affects other optoelectronic components, or the beam reflected from other optoelectronic components affects the signal of the MPD 30, and the collimator Since a portion of the beam emitted toward the lens 40 is used, the situation of reducing the efficiency of the beam and the problem of complicated coating specifications of the beam splitter 20 are not used.

2 is a view for explaining another method of taking a part of the beam emitted from the laser diode in the optical pickup device.

Unlike the method illustrated in FIG. 1, in FIG. 2, the intensity of the beam emitted from the laser diode 10 is measured by using a beam leaving the beam splitter 20. Therefore, the problem presented in FIG. 1 can be solved.

However, the method shown in Fig. 2 is not a problem for an optical pickup for a desktop PC or a player having a relatively large component installation space, but there are many limitations in position selection in the case of a slim optical pickup having a relatively small space.

The monitor photo detector cell for converting actual light into an electrical signal in the MPD 30 has various conversion efficiencies depending on the manufacturer, model, material, and the like. This is referred to as MPD 30 sensitivity, which is an important measure of design.

Since the signal of the MPD 30 has a wide variety of configurations and performance in the case of the optical pickup, it is not easy to meet the necessary conditions using the commercially available MPD 30. Therefore, the core of the design is to properly adjust the position of the MPD 30 so that an appropriate amount of light is incident on the MPD 30.

3 is a diagram illustrating an example of a conventional MPD, in which a front view (FIG. 3A), a side view (FIG. 3B), and a perspective view (FIG. 3C) of the MPD are shown.

Looking at the conventional MPD (30) shown in Figure 3, the width is 3.8mm in width, 3.0mm in height, 1.1mm in height from the side view.

An electrode 33 is formed on the side of the PCB 32, and a monitor photo detector cell (hereinafter referred to as PD Cell) 31 for detecting a beam is positioned at the center portion. In addition, the upper side of the PD Cell 31 is formed of a transparent layer for detecting the beam.

Since the electrodes (or "pins") 33 located on both sides cannot be reduced in number, it is not easy to reduce the MPD 30 to a smaller size in a general IC manufacturing process.

Currently, the height regulation of slim optical pickups requires heights of 5.4mm for general slim optical pickup for notebooks and 3.5mm or less for ultra-thin ultra slim.

Therefore, it is not easy to install the MPD 30 as shown in FIG. 2, and it is not easy to reduce the size of the MPD 30 as described above.

As a method of solving the problems, a method of installing the MPD 30 by tilting it as shown in FIG. 4 has been proposed. However, as the beam is inclined at a predetermined angle, a large amount of reflection and diffuse reflection may occur. Measurement is accompanied by a difficult problem. In addition, the sensitivity is sensitively changed by the mechanical error.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object thereof is to provide an optical pickup device having an improved structure of a monitor photo detector for accurately measuring the intensity of a beam emitted from a laser diode.

Another object of the present invention is to provide an optical pickup device having an improved structure of the monitor photo detector so that the height of the monitor photo detector can be reduced and installed.

An optical pickup apparatus according to the present invention comprises a laser diode for generating a laser for recording or reproducing information, a photo detector for reading a beam reflected from an optical disk, a beam splitter for beam separation, and An optical pickup device comprising an objective lens for collecting at an accurate point and a monitor photo detector for measuring beam intensity emitted from the laser diode, the monitor photo detector comprising: a PC, an electrode formed on a side of the PC; The transparent layer on the upper side of the PC, and the monitor photo detector cell located on the upper side of the PC, characterized in that it is included.

In addition, an opaque layer for blocking light is formed on the transparent layer.

In addition, the monitor photo detector is characterized in that the installation is substantially parallel to the center of the beam emitted from the laser diode.

An optical pickup apparatus according to the present invention comprises a laser diode for generating a laser for recording or reproducing information, a photo detector for reading a beam reflected from an optical disk, a beam splitter for beam separation, and An optical pickup device comprising an objective lens collecting at an accurate point and an MPD for measuring beam intensity emitted from the laser diode, wherein the MPD includes a PCB, an electrode formed on a side of the PCB, and an upper side of the PCB. The transparent layer, and located on the upper side of the PCB characterized in that it comprises a PD Cell installed toward the side.

In addition, an opaque layer for blocking light is formed on the transparent layer.

In addition, the MPD is characterized in that installed in substantially parallel to the center of the beam emitted from the laser diode.

Hereinafter, an optical pickup apparatus according to the present invention will be described in detail with reference to the accompanying drawings.

5 is a perspective view of an MPD of the optical pickup apparatus according to the present invention, and FIG. 6 is a view for explaining an example in which the MPD is installed.

5 and 6, the MPD 60 has a lower portion formed of a PCB 62 and an electrode 63, and the PD Cell 61 is positioned on the side of the upper side of the PCB 62. In the conventional MPD (60), the PD Cell is located upward.

In addition, the upper side of the transparent layer 64 is provided with an opaque layer 65 so that the light reflected from the external photoelectric device affects the MPD 60 and the light reflected from the MPD 60 is the external photoelectric device. It is desirable to minimize the impact on

The MPD 60 allows the beam emitted from the laser diode 10 to be incident through the side surface, and the PD Cell 61 positioned toward the side receives the beam at a nearly vertical angle of incidence, thereby measuring the intensity of the beam. It is possible.

Since the PD Cell 61 has a diameter of about 0.3 to 1.0 mm, the PD Cell 61 can be sufficiently operated through a beam incident through the side surface.

In this case, the PD Cell 61 may be installed such that the beam emitted from the laser diode 10 is incident almost vertically. In this case, the MPD 60 is installed at an angle substantially parallel to the beam axis. That is, it can be installed at an angle of approximately 0 degrees to 20 degrees.

Of course, the installation angle of the MPD 60 may vary depending on the design or sensitivity of the PD Cell 61.

Compared with FIG. 2, since the PD Cell 31 of the MPD 30 is installed upward, the MPD 30 occupies a large height. In comparison with FIG. 4, the MPD 30 has a large height. It does not occupy, but the beam is obliquely incident.

On the other hand, in the present invention, the MPD (60) does not differ a large height, the beam can be incident almost vertically, and preferably provided with an opaque layer 65 to block the light from the outside to accurately measure the intensity of the beam This is possible.

The present invention has the advantage that it is possible to measure the exact beam intensity while making the height of the monitor photo detector small.

In addition, the present invention has the advantage that it is possible to measure the intensity of the beam more accurate by blocking the light from the external optoelectronic device and the light affecting the external photoelectric device by providing an opaque layer.

Claims (3)

Laser diodes for generating laser beams for recording or reproducing information, beam splitters for beam separation, objective lenses for collecting the beams at the correct points on the optical disk, and measurement of beam intensity emitted from the laser diodes. An optical pickup apparatus comprising a monitor photo detector for The monitor photo detector includes a PCB, an electrode formed on a side of the PCB, a transparent layer on an upper side of the PCB, a monitor photodetector cell located on the side of the PCB and facing toward the side, and an outside of the transparent layer. Optical pickup device comprising an opaque layer for blocking light. delete The method of claim 1, The monitor photo detector is installed in substantially parallel to the center of the beam emitted from the laser diode, the optical pickup device, characterized in that for measuring the intensity of the beam incident to the monitor photo detector cell installed toward the side.

Images