KR100463424B1 - Photo-diode for the optical pick-up device - Google Patents

Abstract

By providing a barrier that blocks the interference between the main beam and the sub-beams between the main beam spot portion and the sub beam spot portion of the optical detector, it is possible to prevent deterioration of pickup characteristics due to the inter-beam interference, and misalignment or change of time of the optical pickup. It has an effect that can prevent the deterioration of pickup characteristics.

Description

Photodetector of optical pickup device {PHOTO-DIODE FOR THE OPTICAL PICK-UP DEVICE}

The present invention relates to a photodetector of an optical pickup device. More specifically, in the optical detection unit of the optical pickup device that reads and writes data to and from the disk, a main beam and a sub beam spot unit for obtaining a focus error signal and a sub beam spot unit for obtaining a tracking error signal are provided with a barrier. The present invention relates to a photodetector of an optical pickup apparatus capable of preventing deterioration of pickup characteristics due to interference between sub-beams.

In general, an optical pickup apparatus that reads and reproduces a signal stored in a recording medium such as an optical disk includes a push-pull optical pickup apparatus using a four-segment light receiving element and a three beam (3Beam) using an eight-segment light receiving element. It is divided into the optical pickup device of the type. Here, the three-beam optical pickup device is used for a high-density disc that requires a more accurate tracking servo operation, and the present invention also corresponds to this.

A three-beam optical pickup apparatus which is commonly used includes a light source (LD: Laser Diode) 1 emitting one beam as shown in FIG. 1; A diffraction grating (2) for dividing the light beam emitted from the light source (1) into one main beam and two sub beams; A beam splitter (3) for reflecting the beam from the diffraction grating (2) to the optical disk and transmitting the beam reflected from the disk; A collimator lens for condensing parallel light reflected by the beam splitter 3 to form a beam spot on a recording surface of the optical disk, and converting and transmitting divergent light of the beam spot reflected from the recording surface of the optical disk into parallel light. (4); An objective lens 5 for collecting the reflected light passing through the beam splitter 3; It includes a photo detector (PD) 6 for photoelectric conversion of the three beam spots collected by the objective lens 5 into an electrical signal.

On the other hand, the photo detector 6 is used as an 8-segment light receiving element divided into eight independent photoelectric split terminals (A, B, C, D, E1, E2, F1, F2), as shown in FIG. The four split terminals A, B, C, and D in the center are main beam spot portions 6a for receiving the reflected light of the main beams, and two split portions are provided on both sides of the main beam spot portions 6a, respectively. The terminals E1 and E2 (F1 and F2) are sub beam spot portions 6b for receiving the reflected light of the sub beams. However, it will be apparent to those skilled in the art that the number and positions of the split terminals of the main beam spot portion and the sub beam spot portion may be freely changed.

In the optical pickup device configured as described above, the laser of the divergent light emitted from the light source 1 is divided into the main beam and the sub beam by the diffraction grating 2, and then the beam splitter 3 is used in the direction of the optical disc. The reflected light is focused on the optical disk by the collimator lens 4 to form a beam spot, and then reflected on the optical disk and then passed through the beam splitter 3 to be focused by the objective lens 5. It is then detected by the photo detector 6.

In more detail, the diffraction grating 2 is a servo that follows the track of the optical disk and the zero-order light for the servo that reads the information signal and follows the focus of the optical disk, from the light beam emitted from the light source 1. The optical detector 6 detects the main beam focused on the main beam spot 6a, reads the information stored in the light beam, and at the same time the optical disk The focusing signal error of the optical disc is detected, and the tracking signal error of the optical disk is detected using the sub-beams focused on the sub beam spot part 6b.

Thus, the main beam and the sub beam divided by the diffraction grating 2 have different signals. That is, the main beam has a signal for information reading and focusing error tracking and the sub beam has a tracking error tracking. Therefore, when interference occurs between the main beam and the sub beams, the optical pickup characteristics are adversely affected. If each light beam is detected by different split terminals due to a design error or a work error, or if interference occurs between each beam, an error may occur in reproduction or recording of the optical disc, and detection of focusing and tracking errors Edo will adversely affect.

Therefore, the positions of the respective split terminals are set through repeated experiments during the initial design so that each light beam is detected at the predetermined split terminals and interference does not occur between the beams. However, it is not easy to check the effect of the product in actual products, and these disadvantages remain due to the change over time and poor adjustment due to external vibration.

In other words, the conventional optical pick-up apparatus has a problem in that it is not possible to determine whether the optical beams interfere, and thus an error may occur in disc reading deterioration and focusing and tracking error detection due to the interference of the optical beams.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and the optical detector of the optical pickup apparatus which prevents the main beam and the sub-beam divided by the diffraction grating from interfering with each other to prevent deterioration of pickup characteristics. To provide.

The above object is a photodetector of an optical pickup apparatus for reading and writing data on an optical disk, comprising: a main beam spot section for obtaining a focusing error signal; A sub beam spot unit provided on each side of the main beam spot unit and obtaining a tracking error signal; It is achieved by providing a photodetector of an optical pickup device comprising a barrier between the main beam supot portion and the sub beam spot portion to prevent interference between the main beam and the sub beam, wherein the barrier is made of wire. It features.

1 is a schematic view showing a general optical pickup device;

2 is a view showing a light detector structure of a conventional optical pickup device;

3 is a block diagram showing the structure of the optical detector of the optical pickup apparatus according to the present invention,

4 is a side view of the light detector structure of the optical pickup apparatus according to the present invention.

5 is a block diagram showing the structure of a light detector of the optical pickup device according to another embodiment of the present invention.

<Explanation of symbols on main parts of the drawings>

1: laser diode 2: diffraction grating

3: beam splitter 4: collimator lens

5: objective lens 6,60,70: photodetector

6a, 60a: main beam spot portion 6b, 60b, 70b: sub beam spot portion

70a: first main beam spot portion 70b: second main beam spot portion

B: barrier

Hereinafter, the present invention will be described with reference to the accompanying drawings.

3 is a configuration diagram showing the optical detector structure of the optical pickup apparatus according to the present invention, Figure 4 is a side view of the optical detector structure of the optical pickup apparatus according to the present invention.

The present invention is characterized in that a barrier B is provided between the main beam spot portion 60a and the sub beam spot portion 60b which respectively detect the main beam and the sub beam divided by the diffraction grating.

The light detector according to the present invention can be applied not only to the photo detector for a CD player but also to the photo detector for a DVD player.

First, the configuration of the optical pickup apparatus of the CD player is the same as that of FIG. That is, a light source (LD: Laser Diode) 1 for emitting a light beam; A diffraction grating (2) for dividing the light beam emitted from the light source (1) into one main beam and two sub beams; A beam splitter (3) for reflecting the beam from the diffraction grating (2) to the optical disk and transmitting the beam reflected from the disk; A collimator lens for condensing parallel light reflected by the beam splitter 3 to form a beam spot on a recording surface of the optical disk, and converting and transmitting divergent light of the beam spot reflected from the recording surface of the optical disk into parallel light. (4); An objective lens 5 for collecting the reflected light passing through the beam splitter 3; It includes a photo detector (PD) 6 for photoelectric conversion of the three beam spots collected by the objective lens 5 into an electrical signal.

Meanwhile, as shown in FIGS. 3 and 4, the photo detector 60 according to the present invention includes a main terminal composed of (A, B, C, D) split terminals for detecting the main beam divided by the diffraction grating 2. And a sub beam spot unit 60b provided at both sides of the beam spot unit 60a and the main beam spot unit 60a and configured as (E1, E2) (F1, F2) split terminals for detecting the sub beams. A barrier B having a predetermined height and width is provided between the main beam spot part 60a and the sub beam spot part 60b provided at both sides thereof.

The main beam spot unit 60a and the sub beam spot unit 60b obtain a focus error signal and a tracking error signal using the following equation.

FES = (A + D)-(B + C)

TES = (A + B)-(C + D)-k ((E1 + E2)-(F1 + F2) (k is a constant)

In addition, the installed barrier B prevents the main beam which stores the information signal and the focusing error signal and the sub beam which stores the tracking error signal from interfering with each other. It serves as a blocking film to prevent the main beam from being detected by the sub beam spot 60b or the sub beam from the main beam spot 6a due to misalignment or the like. Therefore, interference between beams can be avoided, and each beam can be detected by a predetermined spot portion, so that information contained in the disc is degraded or errors in focusing and tracking signal detection are eliminated. On the other hand, the barrier (B) is preferably provided with a wire.

Next, the present invention in which the barrier B is provided between the beam spot portions can also be applied to a photodetector for a DVD player.

The optical pickup device for a DVD player relates to a device capable of sharing not only a CD series disc but also a DVD series disc by using a laser diode that emits two types of laser beams of 780 nm and 650 nm wavelengths.

An optical pickup apparatus for a DVD player having such a two-wavelength type light source module includes: a light source for emitting two wavelengths of light, each of which emits 650 nm wavelength (for DVD series discs) and 780 nm wavelength of divergent light (for CD series discs); A diffraction grating (2) for dividing the light beam emitted from the light source (1) into one main beam and two sub beams; A beam splitter (3) for reflecting the beam from the diffraction grating (2) to the optical disk and transmitting the beam reflected from the disk; A collimator lens for condensing parallel light reflected by the beam splitter 3 to form a beam spot on a recording surface of the optical disk, and converting and transmitting divergent light of the beam spot reflected from the recording surface of the optical disk into parallel light. (4); An objective lens 5 for collecting the reflected light passing through the beam splitter 3; It includes a photo detector (PD) 6 for photoelectric conversion of the three beam spots collected by the objective lens 5 into an electrical signal.

An optical detector 70 of such a two wavelength type optical pickup device is schematically shown in FIG. The main beam spot portions 70a and 70a` are respectively different from the first main beam spot portion 70a composed of four photoelectric split terminals A, B, C, and D, corresponding to the two-wavelength type light source. A second main beam spot portion 70a 'composed of four split terminals a, b, c, and d is provided. The sub beam spot 70b is provided with two photoelectric split terminals E1 and E2 (F1 and F2), respectively.

Here, the first main beam spot unit 70a reads out information of the 780 nm wavelength light beam for the CD-based disk and simultaneously acquires a focus error control signal of the light beam to detect a focusing error, and the second main beam spot unit ( 70a`) detects the focusing error by reading the information of the 650nm wavelength light beam for a DVD-based disc and at the same time acquiring a focus error control signal of the light beam.The sub-beam spot portion 70b is a sub-beam divided by a diffraction grating. By receiving the reflected light reflected and formed, the tracking error is detected. Here, it will be apparent to those skilled in the art that the number and positions of the split terminals of the main beam spot portion and the sub beam spot portion may be freely changed.

As described above, each beam split by the diffraction grating has different characteristics, so that interference between them causes an error in the read information, which hinders focusing and tracking error detection. Accordingly, by providing the barriers B in the first and second main beam spot portions 70a and 70a` and the subbeam spot portion 70b, respectively, interference between the main beam and the subbeam split in the diffraction grating is eliminated. Can be. Again, the barrier (B) is preferably made of a wire.

As described above, the present invention can provide a barrier to block the inter-beam interference between the main beam and the sub-beam spot of the photo detector to prevent deterioration of pickup characteristics due to the inter-beam interference, and misalignment or over time of the optical pickup It has an effect that can prevent the pickup characteristic deterioration due to the change.

Claims (6)

In the photodetector of the optical pickup device for reading and writing data to a disk, A main beam spot for acquiring a focusing error signal; A sub beam spot unit provided at each side of the main beam spot unit and acquiring a tracking error signal; And a barrier between the main beam supot portion and the sub beam spot portion to prevent interference between the main beam and the sub beam. The photodetector of claim 1, wherein the barrier is made of wire. The optical pickup according to claim 1, wherein the main beam spot portion comprises a first main beam spot portion irradiated with a 780 nm wavelength for a CD series disk and a second main beam spot portion irradiated with a 650 nm wavelength for a DVD series disk. Photodetector of the device. In an optical pickup device that reads and writes data on a disc, A light source emitting at least one beam; A diffraction grating for dividing the beam from the light source into a main beam and a sub beam; A beam splitter for reflecting the beam from the diffraction grating onto the disk and transmitting the beam reflected from the disk; A lens unit for focusing the disk after parallelly reflecting the beam reflected from the beam splitter; The main beam spot portion to which the main beam is irradiated and the sub beam spot portion to which the sub beam is irradiated from the beam transmitted from the beam splitter are provided between the main beam spot portion and the sub beam spot portion to prevent the interference of the beam. Optical pickup device comprising a light detection unit including a barrier. The optical pickup apparatus of claim 4, wherein the barrier is made of wire. The optical pickup according to claim 4, wherein the main beam spot portion comprises a first main beam spot portion irradiated with a 780 nm wavelength for a CD series disk and a second main beam spot portion irradiated with a 650 nm wavelength for a DVD series disk. Device.