KR20070045791A - Photodetector package calibrating coma astigmatism and optical pick-up apparatus using thereof - Google Patents

Abstract

The present invention relates to a photodetector package and an optical pickup apparatus using the same, and in particular, a photodetector package for correcting a coma aberration to correct a coma aberration by causing the molding to be oblique to the light incident surface of the photodetector and an optical pickup apparatus using the same. It is about.

The invention as described above, the board; A photo detector attached to the board and detecting the intensity of incident light; And molding the photodetector attached to the board to protect it from the outside, the molding corresponding to the incidence surface of the photodetector being inclined and formed of a light transmissive material.

Photodetector, Package, Molding Part, Light Transmittance

Description

Photodetector package calibrating coma astigmatism and optical pick-up apparatus using

1 is a block diagram of an optical pickup apparatus according to the prior art.

2A and 2B are cross-sectional views of a photodetector package for coma aberration correction according to an embodiment of the present invention.

3 is a block diagram of an optical pickup apparatus using a coma aberration correction photodetector package according to an embodiment of the present invention.

<Explanation of symbols for the main parts of the drawings>

210: board 220: photodetector

230: molding portion 240: wire bonding

1100: light transmitting unit 1101: light source

1102: wavelength selective grating 1103: coupling lens

1200: light receiving unit 1201: CD wavelength diffraction hologram element

1202: photo detector 1300: optical path converter

1301: optical splitter 1302: mirror

1303: collimating lens 1304: FPD

1400: objective lens 1500; Tilt actuator

1600: optical disc

The present invention relates to a photodetector package and an optical pickup apparatus using the same, and in particular, a photodetector package for correcting a coma aberration to correct a coma aberration by causing the molding to be oblique to the light incident surface of the photodetector and an optical pickup apparatus using the same. It is about.

In general, optical devices such as compact disk read only memory (CD-ROM) drives, compact disk rewritable (CD-RW) drives, and digital versatile disk (DVD) drives read data from a recording medium such as a compact disk (CD). Optical Pickup is installed.

The optical pickup apparatus includes an optical pickup body including a component such as a photodiode for generating a laser beam, and an actuator with an objective lens for condensing a beam generated from the photodiode on a recording medium.

When the objective lens of the optical pickup device is mounted on the optical pickup device, when the tilting or the height is not correct, the beam generated from the photodiode cannot be focused on the recording medium, and thus data cannot be read or written from the recording medium.

One of the main reasons why such an objective lens cannot focus a beam generated from a photodiode on a recording medium is coma aberration.

Coma aberration refers to a shape that appears as a tail of a comet instead of being imaged as a point on a spherical surface of an objective lens when a beam generated from the photodiode is incident not parallel to the optical axis of the objective lens.

Further, when mounting an objective lens on the optical pickup body of the optical pickup device, a device for reducing coma aberration, etc. has been developed so that the beam generated from the photodiode can be focused on the recording medium. For example, a boiling point sensor lens (ASL: Astigmatic Sensor Lens (SL) or Sensor Lens (SL) is inclined in a direction opposite to the inclination direction of the beam splitter between the beam splitter and the photodetector to correct coma aberration.

Referring to FIG. 1, a conventional compatible optical pickup apparatus includes three beams of light from the first light source 100 for realizing tracking servo or focusing servo and a first light source 100 that emits light having a wavelength of approximately 650 nm. The first holder 105 integrally formed with the first grating 103 to be divided into a second light source, the second light source 110 that emits light having a wavelength of about 780 nm, and the second light source 110 to implement a tracking server or focusing servo. The second grating 113 for dividing the light from the light into three beams is provided with a second holder 115 formed integrally. The first holder 105 and the second holder 115 are each provided independently and disposed in different positions. The first light source 100 is for a disk 107 having a relatively thin thickness, such as a DVD, and the second light source 110 is for a disk 117 having a relatively thick thickness, such as a CD.

The light emitted from the first light source 100 is reflected by the first beam splitter 120 and passes through the second beam splitter 123 to be directed toward the relatively thin disk 107. After being reflected by the relatively thin disk 107, the light is transmitted to the photodetector 130 by passing through the first and second beam splitters 120 and 123. In addition, on the optical path between the second beam splitter 123 and the disk 107, the reflection mirror 125 for converting the path of the light irradiated from the first and second light sources 100 and 110, parallel to the light A collimating lens 127 for making a state and an objective lens 129 for focusing incident light on the disk 107 are further provided.

Meanwhile, the light irradiated from the second light source 110 is reflected by the second beam splitter 123 after passing through the second grading 113, and then, the reflective mirror 125, the collimating lens 127, and the like. The light spot is formed on the relatively thick disk 117 via the objective lens 129. Subsequently, the light reflected by the relatively thick disk 117 passes through the objective lens 129, the reflecting mirror 125, the second and first beam splitters 123, 120, and passes through the photodetector 130. It is received.

In addition, a coma aberration correction sensor lens 132 is provided between the first beam splitter 120 and the photodetector 130. The comma aberration correction sensor lens 132 is not configured to have a uniform curvature of the lens surface, but is configured differently in the vertical direction and the horizontal direction. In addition, the first beam splitter 120 is inclined in a direction opposite to the inclined direction so as to remove coma aberration generated in the light passing through the first beam splitter 120.

Light emitted from the first and second light sources 100 and 110 is spectroscopically beamed into three beams by the first and second gratings 103 and 113, and the three thin beams are used to relatively light the disk. The focusing error is detected by differential push-pull for 107 and the 3-beam or push-pull method for the relatively thick disk 117.

However, when coma aberration is corrected using a boiling point sensor lens or a sensor lens between the beam splitter and the photodetector as described above, it is expensive and there is a disadvantage in that reliability is secured as one lens is added.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a photodetector package for coma aberration correction and an optical pickup device using the same to correct the coma aberration without using a high-cost sensor lens. do.

The present invention for achieving the above object, the board; A photo detector attached to the board and detecting the intensity of incident light; And molding the photodetector attached to the board to protect it from the outside, the molding corresponding to the incidence surface of the photodetector being inclined and formed of a light transmissive material.

In addition, the present invention, the light transmitting unit for generating a light beam having a different wavelength; Detecting a focus position of the light beam reflected from the optical disk through the divided PDIC pattern of a predetermined shape, converts the received signal for the light beam reflected and input by the optical disk into an electrical signal, corresponding to the light incident surface A light receiving unit configured to perform coma aberration correction by using the photodetector package in which the molding unit is inclined; An optical path converting unit guiding the light beam emitted from the transmitting unit to the optical disc and guiding the light beam reflected from the optical disc to the light receiving unit; An objective lens for focusing a light beam having a predetermined wavelength input from the optical path converter on a track of an optical disc; And a tilt actuator for performing focusing / tracking control on the objective lens.

2A will be described in detail with respect to the coma aberration correction photodetector package and the optical pickup device using the same according to an embodiment of the present invention with reference to the drawings.

2A is a cross-sectional view of a photodetector package for coma aberration correction according to an embodiment of the present invention.

Referring to the drawings, the photodetector package for coma aberration correction according to an embodiment of the present invention, the photodetector 220 is attached to the board 210, the wire bonding 240, the molding unit 230 is And molded.

In this case, the molding part 230 according to the present invention is inclined to be inclined at a portion corresponding to the light incident surface of the photodetector 220.

As such, when the molding part 230 of the incident surface of the photodetector 220 is inclined obliquely, coma aberration is corrected when arranging the photodetector package to have a direction opposite to the beam splitter.

 Here, the board 210 may be a lead frame board, a printed circuit board may also be used. In addition, the photodetector 220 and the board 210 are wire bonding 240, but flip chip bonding is possible, and flip chip bonding is illustrated in FIG. 2B.

Next, the material of the molding unit 230 may be a light transmissive plastic, an acrylic plastic may be used, and the product name may be zeonex, arton, or the like.

3 is a block diagram of an optical pickup apparatus using a coma aberration correction photodetector package according to an exemplary embodiment of the present invention, which is a DVD / CD compatible optical pickup apparatus.

First, referring to FIG. 3, the transmitting unit 1100 of the optical pickup apparatus including the coma aberration correction photodetector package according to the present invention generates light beams having different wavelengths, and focusing / tracking control of the light beams. For this purpose, the light beam is separated into three beams and emitted to the optical path changing unit 1300, which will be described later, and includes a light source 1101 and a wavelength selective grating 1102.

The light transmitting unit 1100 further includes a coupling lens 1103 for shortening a focal length from the light source 1101 to an optical path changing unit 1300 to be described later to increase coupling efficiency with respect to the light beam. May be

The light source 1101 includes two chips in a single laser diode package to generate both a 650 nm DVD wavelength and a 780 nm CD wavelength to be emitted to the optical path converting unit 1300 to be described later. It is a two wavelength laser diode.

Wavelength-selective grating 1102 is a zero-order, the optical beam for tracking / focusing control of the light beam having a predetermined wavelength emitted from the light source 1101, that is, the wavelength for DVD of 650nm and the wavelength for CD of 780nm + 1,-first diffraction is separated into three beams and then transmitted to the optical path conversion unit 1300 to be described later.

The light receiving unit 1200 detects a focus position of a light beam reflected from the optical disk 1600 through a divided pattern having a predetermined shape, and converts a light receiving signal for the light beam into an electrical signal. The diffraction hologram element 1201 and the photodetector 1202 are comprised.

Here, the CD wavelength diffraction hologram element 1201 diffracts the light beam at a predetermined angle when a light beam having a predetermined wavelength, more specifically, a CD wavelength of 780 nm is incident from the optical path converter 1300, which will be described later. The focus is accurately formed on the photo detector 1202 to be described later.

Here, the CD wavelength diffraction hologram element 1201 diffracts the light beam when a light beam having a predetermined wavelength, more specifically, a DVD wavelength of 650 nm is incident from the optical path converter 1300, which will be described later. It acts as a kind of transparent window that passes through as it is.

The photo detector 1202 receives a light beam reflected from the optical disk 1600 through an optical path converting unit to be described later and converts the light beam into an electrical signal. More specifically, the photo detector 120 is a photo detector PD.

In addition, the photo detector 1202 is attached to the board 1204 and constitutes a package in which the molding 1206 of the light incident surface is formed obliquely (see FIGS. 2A and 2B).

As such, when the molding part 1206 on the incidence side of the photodetector 1202 is inclined obliquely, coma aberration is corrected.

In addition, the photodetector 1202 has a pattern divided into a predetermined shape for accurately detecting a focus position of the light beam input through the optical path changing unit 1300, which will be described later, and more specifically, a spot of the light beam may be formed. After forming the six regions by symmetrically dividing the formed region into three regions, the region is divided into two equal parts and has a PDIC pattern for detecting a focus position divided into a total of 12 regions.

Accordingly, even when the light source 1101 of the light emitting unit 1100 operates at a high output high temperature and the wavelength of the light beam changes in a range of about 15 nm from room temperature, the photodetector 1202 may be configured as described above. By eliminating the deviation of the spot position of the light beam based on the constructed PDIC pattern, the optical signal corresponding to the predetermined data stored in the optical disk 1600 is accurately converted into an electrical signal.

The optical path changing unit 1300 guides the light beam emitted from the light transmitting unit 1100 to the optical disk 1600, and guides the light beam reflected from the optical disk 1600 to the light receiving unit 1200. And a splitter 1301, a mirror 1302, and a collimating lens 1303.

In addition, the optical path converter 1300 may further include an FPD 1304 for detecting the intensity of the light beam input through the optical splitter 1301 and observing the power of the light source based thereon.

Here, the optical splitter 1301 serves to branch the spherical light beam diffracted into three beams incident from the light source 1101 of the transmitting unit 1100 in the direction in which the optical disk 1600 is located. do.

Thereafter, the light beam is reflected from the optical disk 1600 and totally reflected in a right angle direction based on a mirror 1302 to be described later to branch the input light beam in a direction in which the light receiver 1200 is located.

A mirror 1302 totally reflects a spherical wave shaped light beam branched by the optical splitter 1301 in the direction of the optical disk 1600 and enters the collimating lens 1303 to be described later.

The collimating lens 1303 converts a spherical waveform light beam diffracted into three beams totally reflected at right angles based on the mirror 1302 into a planar waveform light beam, which will be described later. The light is incident on the objective lens 1400.

The objective lens 1400 receives the light source of the planar waveform totally reflected at right angles based on the mirror of the optical path changing unit 1300, and then concentrates the light on the track of the optical disk 1600 in which predetermined data is formed. Perform.

The tilt actuator 1500 performs focusing / tracking control on the objective lens 1400.

According to the present invention as described above, it is possible to correct the coma aberration by molding the incidence surface of the photodetector obliquely without providing a separate expensive sensor lens, it is possible to obtain a cost reduction effect.

In addition, according to the present invention, there is an effect that the reliability is secured by correcting coma aberration through the package of the photodetector without providing a separate lens.

Claims (8)

board; A photo detector attached to the board and detecting the intensity of incident light; And A photodetector package for coma aberration correction comprising a molding part formed by forming a photodetector attached to the board to protect from the outside and inclined to correspond to the incident surface of the photodetector and formed of a light transmissive material. The method of claim 1, The board, A photodetector package for coma aberration correction, characterized in that the lead frame or a printed circuit board. The method according to claim 1 or 2, The molding unit is a photodetector package for coma aberration correction, characterized in that the light transmitting plastic. The method according to claim 1 or 2, And the photodetector is wire bonded to the board. The method according to claim 1 or 2, The photodetector package for coma aberration correction, characterized in that the chip is flip-chip bonded to the board. A transmitter for generating light beams having different wavelengths; Detecting a focus position of the light beam reflected from the optical disk through the divided PDIC pattern of a predetermined shape, converts the received signal for the light beam reflected and input by the optical disk into an electrical signal, corresponding to the light incident surface A light receiving unit configured to perform coma aberration correction by using the photodetector package in which the molding unit is inclined; An optical path converting unit guiding the light beam emitted from the transmitting unit to the optical disc and guiding the light beam reflected from the optical disc to the light receiving unit; An objective lens for focusing a light beam having a predetermined wavelength input from the optical path converter on a track of an optical disc; And And a tilt actuator configured to perform focusing / tracking control on the objective lens. The method of claim 6, The light receiving unit, A hologram element for diffracting only a light beam having a wavelength for a CD among light beams input through the optical path changing unit at a predetermined angle; And An optical pickup apparatus having a package structure in which a molding part corresponding to a light incident surface is inclined and including a photo detector package for converting incident light into an electrical signal. The method according to claim 6 or 7, The photodetector package, board; A photo detector attached to the board and detecting the intensity of incident light; And And a molding part formed by molding a photodetector attached to the board to protect it from the outside and having an inclined surface corresponding to the incident surface of the photodetector and formed of a light transmissive material.

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