KR20090010405A - Photodetector and apparatus for optical pickup having the same - Google Patents

Abstract

An optical detector and an optical pickup device including the same are provided to improve compatibility between different optical recording media and remove inter-layer interference of disc and noise of reproduction/recording signal by using light sources emitting different wavelength. An optical detector(300) comprises a first detection unit(310) detecting the light of a first wavelength, a second detection unit(320) which crosses with the first detection unit and detects the light of a second wavelength, and the third detection unit(330) which is located to cross with the first detection unit and apart from the second detection unit and detects the light of a third wavelength. Each detection unit includes cells which detect 0-order, (-1)-order, and (+1)-order light of each wavelength light, respectively.

Description

Optical detector and optical pickup device having same {{PHOTODETECTOR AND APPARATUS FOR OPTICAL PICKUP HAVING THE SAME}

The present invention relates to an optical detector and an optical pickup apparatus having the same, and more particularly, to an optical detector and an optical pickup apparatus applicable to a recording and reproducing apparatus capable of recording and reproducing recording media using three different wavelengths of light. It is about.

As a type of the next generation optical recording medium, a recording medium using a light source by a blue semiconductor laser is adopted. In the case of providing an optical pickup corresponding to such a next-generation recording medium, it is necessary to have compatibility of an optical recording medium using light of different wavelengths, such as a conventional compact disc (CD) and digital versatile disc (DVD).

Therefore, there is a need for an optical pickup device having compatibility between optical recording media of different types of disk structures and accompanying laser specifications, and development of an optical detector applicable thereto is required.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide an optical detector and an optical pickup device capable of providing compatibility between optical record media having different wavelengths.

In order to achieve the above object, the photodetector according to the present invention includes a first detector for detecting light of a first wavelength, a second detector for detecting light of a second wavelength, and a first detector for detecting light of a second wavelength. And a third detector intersecting the detector, arranged at regular intervals from the second detector, and detecting light of a third wavelength.

The first detection unit detects a zeroth order light among the light of the third divided first wavelength and second and third cells that detect + 1st order and -1st order light among the light of the third divided first wavelength, respectively. It may include.

The first cell may include four photodiodes, and the second and third cells may each include two photodiodes.

The second detector is configured to detect the fourth order light among the light of the third wavelength divided by the fourth cell and the fifth and sixth cells which detect + 1st and -1st light of the light of the third divided second wavelength, respectively. The third detector may include a first cell that detects zeroth order light in the light of the third wavelength and the third wavelength and a seventh light that detects + 1st and -1st light of the light of the third wavelength. And an eighth cell.

The fourth to eighth cells may include four photodiodes.

The second and third cells may have a sensitivity three times the sensitivity of the fifth to eighth cells.

The second and third cells may be arranged at intervals of 700 to 720 um from the first cell, respectively.

The first wavelength may be 405 nm, the second wavelength may be 650 nm, and the third wavelength may be 780 nm.

The photo detector may further include two switches for mode switching corresponding to the first to third wavelengths.

On the other hand, the optical pickup device according to the present invention is a light source unit for generating light of different first wavelength, second wavelength and third wavelength, a beam splitter for splitting the light generated from the light source, collie for converting the split light into parallel light A mate lens, an objective lens for irradiating parallel light to the recording surface of the recording medium, and an optical detector for detecting light reflected from the recording medium, the optical detector comprising: a first detector for detecting light of a first wavelength and a first detector; And a second detector for detecting light having a second wavelength, and a second detector for detecting light having a second wavelength, and arranged to be spaced apart from the second detector, and having a third detector for detecting light having a third wavelength. .

The light source unit may include a first light source for generating light of the first wavelength and a second light source for generating light of the third wavelength.

As described above, the optical detector and the optical pickup apparatus of the present invention may correspond to a recording medium using light having three different wavelengths.

In addition, according to the present invention, it is possible to eliminate interlayer interference and noise of a reproduction recording signal in a multi-layer disc.

As used herein, the term " recording medium " means any medium in which data is recorded or capable of recording, and may be, for example, an optical disc. In addition, the "recording and reproducing apparatus" includes not only apparatuses capable of recording or reproducing but also apparatuses capable of both recording and reproducing using the above-described recording medium.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily understand.

The optical pickup apparatus according to the embodiment of the present invention enables recording or reproducing with respect to an optical recording medium using light having different wavelengths when recording or reproducing.

Hereinafter, the optical pickup apparatus uses a first recording medium using light of a first wavelength having a wavelength of about 405 nm as recording / reproducing light, a second recording medium using light of a second wavelength having a wavelength of about 660 nm as recording / reproducing light, As an example, recording or reproducing is performed for a third recording medium which uses light having a third wavelength having a wavelength of about 785 nm as recording / reproducing light.

1 is a schematic diagram of an optical pickup device according to an embodiment of the present invention. As shown in FIG. 1, the optical pickup apparatus according to the exemplary embodiment includes a light source unit 100, an optical system 200, and a photo detector 300.

The light source unit 100 includes a first light source 10 for generating light of a first wavelength and a second light source 12 for selectively generating light of a second wavelength and a third wavelength. In this case, the first light source 10 and the second light source 12 may be formed of a laser diode. In addition, the light source unit 100 includes first and second diffraction gratings that separate light having the first to third wavelengths generated by the first and second light sources 12 into 0th order, + 1st order and -1st order light, respectively. (14, 16) further. However, the present invention is not limited thereto, and the light source unit 100 may be formed of one laser diode capable of selectively generating light of the first to third wavelengths. In this case, one diffraction grating may be provided.

The optical system 200 includes a first beam splitter 18, a second beam splitter 20, a collimate lens 22, a quarter wave plate 24, an objective lens 26, A mirror 28 and a sensor lens 30.

The first beam splitter 18 combines the optical path of the light generated by the first light source 10 and the optical path of the light generated by the second light source 12. For example, the first beamsplitter 18 has a mirror surface with wavelength selectivity. The mirror surface is configured to transmit light of the first wavelength generated from the first light source 10 and reflect light of the second and third wavelengths generated from the second light source 12. Accordingly, the first beam splitter 18 may synthesize an optical path of light having the first to third wavelengths.

The second beam splitter 20 branches the return light reflected from the recording surface of the recording medium 400 to the photo detector 300.

The collimating lens 22 converts the divergence angle of the light having the first to third wavelengths so that the light travels in parallel, and the quarter wave plate 24 converts the light into circularly polarized light.

The objective lens 26 condenses the light generated by the light source unit 100 on the recording surface of the recording medium 400.

The sensor lens 30 collects the return light branched from the second beam splitter 20 toward the photo detector 300 to the photo detector 300. For example, the sensor lens 30 may be a cylindrical lens.

The photo detector 300 detects the return light reflected from the recording surface of the recording medium 400 and converts it into an electrical signal. The detailed configuration of the photo detector 300 will be described later.

The light generated by the first light source 10 or the second light source 12 of the light source unit 100 is split in the first diffraction grating 14 or the second diffraction grating 16, respectively, and the first beam splitter 18, The recording medium 400 is irradiated through the second beam splitter 20, the quarter wave plate 24, the collimated lens 22, the mirror 28, and the objective lens 26.

The beam reflected from the recording medium 400 passes through the objective lens 26, the mirror 28, the collimated lens 22 and the quarter wave plate 24, and is reflected by the second splitter to reflect the light detector 300. ) Is incident.

As described above, the photo detector 300 according to the embodiment of the present invention receives light having the first to third wavelengths and converts the light into an electrical signal. Hereinafter, the configuration of the photo detector 300 will be described in detail.

2 is a schematic diagram showing device arrangement of the photodetector 300 according to an embodiment of the present invention. As shown in FIG. 2, the photo detector 300 includes a first detector 310 for detecting light having a first wavelength, a second detector 320 for detecting light having a second wavelength, and a third wavelength. And a third detector 330 for detecting light. For example, the first wavelength may be 405 nm, the second wavelength may be 650 nm, and the third wavelength may be 780 nm.

In this case, the first detector 310 is disposed to intersect the second detector 320 and the third detector 330, and the second detector 320 and the third detector 330 are disposed parallel to each other at regular intervals. do.

Light of each wavelength is divided into three by the diffraction grating mentioned above. At this time, the first detection unit 310 is a first cell 32 for detecting the 0th order light among the light of the first wavelength divided into three, and the second cell 34 for detecting the + 1st and -1st order light respectively. And a third cell 36.

At this time, the first cell 32 is composed of a four-split photodiode, and the second cell 34 and the third cell 36 are composed of a two-split photodiode. That is, as shown, the first cell 32 includes four photodiodes A, B, C, and D, and the second cell 34 includes two photodiodes X1 and X2. The third cell 36 includes two photodiodes Y1 and Y2.

In this case, the second cell 34 and the third cell 36 are disposed at intervals of 700 to 720 um from the first cell 32, respectively. Accordingly, interlayer interference and noise between cell signals, which may occur when using a multi-layer recording medium having two or more recording layers, can be eliminated.

In addition, the size of the second cell 34 and the third cell 36 may be larger than other cells to secure a grating margin.

In addition, the relative position or angle of the photodetector 300 may be adjusted using the signals of the second cell 34 and the third cell 36. For example, the position and the disposed angle of the photo detector 300 are adjusted by using the difference in the amount of light of X1 and X2 detected through the pins 6 and 10 of FIG. 2. This eliminates the need for a separate optical axis correction device.

On the other hand, the second detection unit 320 is a fourth cell 38 for detecting the 0-th order light of the light of the third wavelength divided by the fifth cell 40 for detecting the + 1st and -1st order light and Sixth cell 42 is included.

In this case, the fourth to sixth cells 38, 40, and 32 are formed of a four-divided photodiode. That is, as shown, the fourth cell 38 includes four photodiodes a, b, c, and d, and the fifth cell 40 has four photodiodes e1, e2, e3, and e4. ), And the sixth cell 42 includes four photodiodes f1, f2, f3, f4.

On the other hand, the first cell 32 detects the zero-order light among the light of the third wavelength divided by the third wavelength as well as the zero-order light of the first wavelength. That is, the first detector 310 and the third detector 330 share the first cell 32. In addition to the first cell 32, the third detector 330 includes a seventh cell 44 and an eighth cell 46 that detect + 1st and -1st light, respectively.

In this case, the seventh and eighth cells 46 may be formed of a quadrant photodiode. That is, as shown, the seventh cell 44 includes four photodiodes e1, e2, e3, and e4, and the eighth cell 46 includes four photodiodes f1, f2, f3, and f4. ).

Thus, by providing separate cells for the light of the second wavelength and the third wavelength, it is possible to obtain a more precise signal for the light of each wavelength than when using the same cell can improve the characteristics of the servo and optical pickup. .

At this time, when the second light source 12 is a two-wavelength laser diode that generates light of the second wavelength and the third wavelength, for example, 650 nm and 780 nm, as described above, The distance between the centers of the cells using the second wavelength and the third wavelength to match the interval of light may be 100 to 130 um.

As described above, the photodetector 300 according to the present exemplary embodiment detects a signal generated from light having three different wavelengths, including a total of 28 photodiodes.

In addition, the photo detector 300 further includes two switches SW1 and SW2 for mode switching corresponding to the first to third wavelengths. 3 is a table illustrating an example of a cell selection method according to a switch mode, and FIG. 4 is a table illustrating an example of cell sensitivity according to a switch mode.

When a recording medium using a specific wavelength of light is loaded into the recording / reproducing apparatus, the recording / reproducing apparatus having the optical pickup recognizes this and switches the switch SW1 to select an appropriate sensitivity for each wavelength according to the type of recording medium. , SW2) changes the gain. Accordingly, the sensitivity for each wavelength can be selected. In this case, as shown in FIG. 4, a total of six modes may be switched by combining gains of the switches SW1 and SW2.

Meanwhile, the tracking error signal (TES) may be detected by the differential push pull (DPP) method using the photodetector 300 according to the exemplary embodiment of the present invention. In this case, TES when recording or reproducing a recording medium using light of a first wavelength can be expressed by the following equation.

 TES = (A + B)-(C + D) -K [(X1 + Y1)-(X2 + Y2)]

In this case, as shown in FIG. 4, in order to secure an appropriate K value, the second cell 34 and the third cell 36 are three times the sensitivity of the fifth to eighth cells 40, 42, 44, and 46. It may have a sensitivity of magnitude.

On the other hand, the photo detector according to the embodiment of the present invention configured as described above may be formed of a photodiode integrated circuit (PDIC).

Although the preferred embodiments of the present invention have been described above, the present invention is not limited thereto, and various modifications and changes can be made within the scope of the claims and the detailed description of the invention and the accompanying drawings, and the present invention is also provided. Naturally, it belongs to the range of.

1 is a schematic diagram of an optical pickup device according to an embodiment of the present invention.

2 is a schematic diagram showing an element arrangement of a photo detector according to an embodiment of the present invention.

3 is a table showing an example of a cell selection method according to a switch mode.

4 is a table showing an example of cell sensitivity according to a switch mode.

Claims (19)

A first detector for detecting light of a first wavelength; A second detector crossing the first detector and detecting light having a second wavelength; And A third detector intersecting the first detector, arranged at regular intervals from the second detector, and configured to detect light of a third wavelength Photodetector comprising a. According to claim 1, The first detector may include a first cell that detects zeroth order light among the light of the third wavelength divided by the first cell and a + 1st order and -1st order light of the light of the first wavelength divided by three; A photo detector comprising a third cell. The method of claim 2, Wherein the first cell comprises four photodiodes and the second and third cells each comprise two photodiodes. The method of claim 3, wherein The second detector is configured to detect a fourth cell that detects zeroth order light among the light of the third wavelength divided by the second wavelength, and fifth and fourth order light which detects + 1st and -1st light of the light of the second wavelength divided by the third cell; Including a sixth cell, The third detector may be configured to detect the first cell and the first and second order light, respectively, of the light of the third wavelength and the third wavelength, respectively. And an eighth cell. The method of claim 4, wherein And the fourth to eighth cells comprise four photodiodes. The method of claim 4, wherein And the second and third cells have a sensitivity three times the sensitivity of the fifth to eighth cells. The method of claim 2, And the second and third cells are arranged at intervals of 700 to 720 um from the first cell, respectively. According to claim 1, The first wavelength is 405 nm, the second wavelength is 650 nm, and the third wavelength is 780 nm. According to claim 1, And two switches for mode switching corresponding to the first to third wavelengths. A light source unit generating light having different first wavelengths, second wavelengths, and third wavelengths; A beam splitter dividing the light generated by the light source; A collimated lens for converting the divided light into parallel light; An objective lens for irradiating the parallel light onto a recording surface of a recording medium; And A photo detector for detecting light reflected from the recording medium, The photo detector, A first detector for detecting light of a first wavelength; A second detector crossing the first detector and detecting light having a second wavelength; And A third detector intersecting the first detector, arranged at regular intervals from the second detector, and configured to detect light of a third wavelength Optical pickup device comprising a. The method of claim 10, The first detector may include a first cell that detects zeroth order light among the light of the third wavelength divided by the first cell and a + 1st order and -1st order light of the light of the first wavelength divided by three; An optical pickup apparatus comprising a third cell. The method of claim 11, wherein Wherein the first cell comprises four photodiodes, and the second and third cells each comprise two photodiodes. The method of claim 12, The second detector is configured to detect a fourth cell that detects zeroth order light among the light of the third wavelength divided by the second wavelength, and fifth and fourth order light which detects + 1st and -1st light of the light of the second wavelength divided by the third cell; Including a sixth cell, The third detector may be configured to detect the first cell and the first and second order light, respectively, of the light of the third wavelength and the third wavelength, respectively. And an eighth cell. The method of claim 13, And the fourth to eighth cells include four photodiodes. The method of claim 13, And the second and third cells have a sensitivity three times the sensitivity of the fifth to eighth cells. The method of claim 11, wherein And the second and third cells are arranged at an interval of 700 to 720 um from the first cell, respectively. The method of claim 9, The first wavelength is 405 nm, the second wavelength is 650 nm, and the third wavelength is 780 nm. The method of claim 9, The optical detector further comprises two switches for mode switching corresponding to the first to third wavelengths. The method of claim 9, The light source unit, A first light source for generating light of the first wavelength; And And a second light source for generating light of the second wavelength and the third wavelength.

Images