KR20050097214A - Combo type's apparatus for optical pick-up using laser diode of 2 chips 1 package - Google Patents

Abstract

The combo optical pickup device using a two-wavelength (2 Chips 1 Package) laser diode according to the present invention is a DVD for laser light emitted through a light emitting means composed of a hybrid semiconductor chip for emitting laser light for DVD and CD. Laser light performs adjustment for defocus through the sensor lens, and CD laser light performs adjustment for defocus through the hologram to perform tracking / focus servo tracking for optical discs for DVD and CD.

Accordingly, the present invention provides a combo-type optical pickup device capable of recording on both DVD and CD, which is simple in configuration and inexpensive to manufacture, by using a hybrid two-wavelength semiconductor chip, and has a two-wavelength monolithic shape. It provides an advantage that the semiconductor chip can be used without changing the design of the optical system.

Description

Combo type's apparatus for optical pick-up using laser diode of 2 Chips 1 Package}

The present invention relates to a combo-type optical pickup device using a two-wavelength (2 Chips 1 Package) laser diode.

More specifically, the DVD laser light is defocused through the sensor lens among the laser light emitted from the light emitting means in which the semiconductor chips for DVD and CD are formed in a hybrid shape, and the CD laser light is decoded through the hologram. A combo type optical pickup apparatus for performing tracking / focus servo tracking for optical discs for DVDs and CDs by performing focus adjustment.

In general, an optical disc player such as a CD player or a DVD player is equipped with an optical pickup device for recording and reproducing data. The optical pickup follows the optical disc by the optical pickup actuator after irradiating the detection light to the recording surface of the optical disc. Focusing and tracking servos of the detection light, receiving light reflected from the servo-following optical disk, converting the light into an electrical signal, and reproducing information.

Here, since many users are more accustomed to the relatively inexpensive and widespread CD player among the conventional optical disc players, even if the performance of the DVD player is excellent, the DVD player which is not compatible with the CD player is competitive in the sales market. For this reason, all DVD products on the market are manufactured in the form of DVD / CD combos to be compatible with CD discs.

In the optical system of a DVD product compatible with the optical disc for CD as described above, two light source modules having different wavelengths, that is, wavelengths of 650 nm and 780 nm are conventionally used, but in recent years, the number of components of the optical system has been reduced. For this purpose, one light source module that has two semiconductor chips embedded and outputs two wavelengths at the same time is used.

That is, the optical pickup device for DVD currently used comprises a semiconductor chip that emits a 650 nm wavelength DVD laser light used for reproduction / recording of a DVD disc, and a semiconductor chip that emits a 780 nm wavelength CD laser light. The light source module is configured in one of a monolithic type and a hybrid type.

Here, in the monolithic light source module, a semiconductor chip emitting laser light of an infrared wavelength for a DVD and a semiconductor chip emitting laser light of a red wavelength for a CD are integrated on the same substrate to form a package. It has a structure.

Therefore, the light source module of the monolithic type configured as described above has an advantage that the position tolerance between the two semiconductor chips can maintain the accuracy of 120 ± 1 μm, but there is a disadvantage in that the manufacturing cost is relatively high. There is a limit to the application to the light source module of the optical pickup device.

The hybrid type light source module has a package shape in which a semiconductor chip emitting laser light of an infrared wavelength for a DVD and a semiconductor chip emitting laser light of a red wavelength of a CD are arranged side by side on a substrate. Has a structure.

Therefore, the hybrid type light source module configured as described above has a disadvantage in that offset is easily generated in the light receiving part due to a relatively large position tolerance of 120 ± 10 μm between two semiconductor chips. Due to the advantages of easier manufacturing and lower manufacturing cost than a monolithic light source module, it is widely used in a combo optical pickup device for a DVD / CD.

The disadvantage of the optical pickup device to which the hybrid type light source module is applied is that the optical axis for each wavelength does not coincide with each other due to the positional tolerance between the two semiconductor chips as described above. Offset occurs with respect to the wavelength.

That is, when the optical axis for any one of the wavelengths for the CD or DVD is adjusted, the optical axis for the other wavelength is relatively inclined, thereby causing coma aberration and the like on the optical disk.

As a method for solving such a problem, conventionally, a holographic element (HOE) or a diffractive optic element (DOE) is disposed in front of a semiconductor chip to coincide with an optical axis of a laser beam emitted from two semiconductor chips. And a method of matching the optical axis by varying the reflection position for each wavelength by providing a coating layer having a thickness of about 0.2 mm on the beam splitter, and a method of compensating through the actuator tilt.

That is, a hologram element that performs diffraction on a laser light having a specific wavelength among the laser light emitted from the DVD semiconductor chip and the CD semiconductor chip constituting the light source module is placed in front of the light receiving unit, and then diffracted for the specific wavelength. The tracking / focus servo tracking was performed by focusing on one photodetecting element formed in the light receiving unit and focusing on the photodetecting element without diffraction for another wavelength.

However, the tracking / focus servo tracking method using the optical pickup device configured as described above is difficult to construct an optical system for reading tracking / focusing error signals for different wavelengths emitted from two semiconductor chips, and emits due to disturbance such as external temperature. When the wavelength of the light is changed, the optical axis center of the laser light passing through the hologram element moves to the left and right without focusing on the center of the photodetecting device, thereby causing an offset error.

In order to solve the problems described above, the DVD laser light is defocused by the sensor lens and the CD laser light is defocused by the hologram. The present invention provides a combo-type optical pickup device using a two-wavelength (2 Chips 1 Package) laser diode that performs tracking / focus servo tracking for optical discs for DVD and CD.

According to an aspect of the present invention, there is provided a combo-type optical pickup device using a two-wavelength (2 Chips 1 Package) laser diode, comprising: light emitting means for emitting two-wavelength laser light for tracking / focusing servo tracking of an optical disk; Optical means for focusing a diffraction beam formed by performing diffraction on the two-wavelength laser light at a track pitch of an optical disc, and transmitting a diffracted beam reflected by the track pitch to the outside; A sensor lens for adjusting defocus of an optical spot formed by a diffraction beam reflected from an optical disc for DVD among the diffraction beams incident through the optical means; A hologram for diffusing light spots formed by the diffraction beams reflected from the optical disc for CD among the diffraction beams incident through the optical means at a predetermined angle to adjust defocus; And a second photodetection area for focusing the light spot whose defocus is adjusted by the sensor lens, and a second spot for focusing the light spot whose defocus is adjusted by the hologram at a predetermined interval from the first light detection area. And light detecting means for detecting a tracking / focusing error signal of the optical disc by using the light distribution of the light spots focused on the first and second light detecting areas.

Hereinafter, a configuration and an operation process of a combo-type optical pickup device using a 2-wavelength (2 Chips 1 Package) laser diode according to the present invention will be described in detail with reference to the accompanying drawings.

First, a configuration of a combo type optical pickup device using a two-wavelength (2 Chips 1 Package) laser diode according to the present invention will be described with reference to FIG. 1.

The combo-type optical pickup apparatus using a two-wavelength (2 Chips 1 Package) laser diode according to the present invention includes a diffraction pattern of a DVD laser light whose defocus is adjusted by a light detection means by a sensor lens among diffraction beams incident from an optical disc. The tracking / focus servo tracking is performed by using the light intensity distribution of the diffraction pattern of the CD laser light whose defocus is adjusted in the light detection means by the hologram, as shown in FIG. 1. , An optical means 200, a sensor lens 300, a hologram 400, and a light detection means 500.

Here, the light emitting means 100 records / reproduces audio / video information data on the optical disc 600 having a track pitch having a predetermined shape, or focus / tracking for accurately reading the information data recorded at the track pitch. The first semiconductor chip 110 that emits laser light having a red wavelength for a DVD, and the second semiconductor chip 120 that emits laser light having an infrared wavelength for a CD, which emits laser light for detecting a signal, are hybrid. It has a structure packaged in a shape.

Optical means 200 serves to focus the laser light emitted from the light emitting means 100 on the track pitch formed on the optical disk 600, as shown in Figure 1, the diffraction plate 210, The beam splitter 220, the collimator lens 230, the wave plate 240, and the objective lens 250 are configured to be included.

Here, the diffraction plate 210 performs diffraction on the laser light emitted from the light emitting means 100 to linearly polarize light having a diffraction coefficient of a predetermined diffraction coefficient, more specifically, 0th order, + 1st order, and -1st order. After forming the diffraction beam of the shape, and serves to transfer it to the beam splitter 220, more specifically grating.

The beam splitter 220 serves to branch a linearly polarized diffraction beam having a predetermined diffraction coefficient incident from the diffraction plate 210 in the direction in which the optical disc 600 is located.

In addition, the beam splitter 220 receives the diffracted beam reflected from the optical disc 600, and then the sensor lens 300 and the hologram 400 which describe the diffraction beam for tracking / servo following the optical disc 600. And branching in the direction in which the photodetecting means 500 is located.

The collimator lens 230 converts a diffraction beam having a predetermined diffraction coefficient branched by the beam splitter 220 into a parallel diffraction beam into a wave plate 240.

The wave plate 240 forms a circularly polarized diffraction beam from a linearly polarized diffraction beam having a predetermined diffraction coefficient incident in parallel from the collimator lens 230 and then enters the circularly polarized diffraction beam into the objective lens 250. Perform.

The objective lens 250 is an optical disk 500 for storing predetermined image and audio data information for diffracted beams incident from the wavelength plate 240, more specifically, an optical disk for CD or 650 nm using an infrared wavelength of 780 nm. It serves to focus the track pitch of the optical disc for DVD using the red wavelength of.

When the diffraction beam reflected from the optical disc for DVD is incident through the beam splitter 220 of the optical means 200, the sensor lens 300 adjusts the defocus of the diffraction beam and the light detecting means 500. Focusing on the photodetection patterns 511, 512, and 513 of a predetermined shape formed in the first photodetection region 510 of FIG.

That is, when the diffraction beam having a predetermined diffraction coefficient is reflected from the optical means 100 from the optical disc for optical disc 100, the diffraction beam having a zero-order diffraction coefficient is shown as shown in FIG. The first light divided into four areas (A), (B), (C) and (D) for detecting a focusing error signal using astigmatism among the first photodetection areas 510. The focusing function is performed on the detection pattern 511.

In addition, the sensor lens 300 is a tracking error signal using a differential push-pull (DPP) method of the light spot 700 formed by the diffraction beam having a + 1st order diffraction coefficient in the first light detection region 510. Focusing on the second photodetection pattern 512 divided into two regions (E1) and (E2) for detecting?

In addition, the sensor lens 300 is a tracking error signal using a differential push-pull (DPP) method of the light spot 700 formed by a diffraction beam having a -first order diffraction coefficient among the first light detection region 510. It focuses on the third photodetection pattern 513 divided into (F1), (F2) region for detecting the.

When the diffraction beam reflected from the optical disc for CD is incident through the beam splitter 220 of the optical means 200, the hologram 400 adjusts the defocus of the diffraction beam and the light detection means 500 The diffraction beam is focused onto the photodetection patterns 521, 522, and 523 having a predetermined shape formed in the second photodetection region 520 of the.

That is, the hologram 400, when the diffraction beam having a predetermined diffraction coefficient is reflected from the CD optical disk through the optical means and is incident, the light spot 700 of the diffraction beam having a diffraction coefficient of a specific order is the second Focusing on the fourth photodetection pattern 521 divided into four areas (A), (B), (C) and (D), which detects a focusing error signal using divisional astigmatism in the photodetection area 520. Play a role.

In addition, the hologram 400 detects a tracking error signal using a modified push-pull (MPP) method among the light spots 700 formed by the diffraction beam having a + 1st order diffraction coefficient among the second light detection regions 520. It focuses on the fifth light detection pattern 522 divided into two regions (E1) and (E2) to be detected.

In addition, the hologram 400 detects a tracking error signal using a modified push-pull (MPP) method among the light spots 700 formed by the diffraction beam having a -first order diffraction coefficient among the second light detection regions 520. It focuses on the sixth light detection pattern 523 divided into two regions (F1) and (F2) to be detected.

Here, when the wavelength of the CD laser light emitted from the second semiconductor chip 120 of the light emitting means 100 changes due to a change in temperature, the hologram 400 changes the diffraction angle according to the changed wavelength. In order to correspond to the first and second hologram patterns having different diffraction angles are formed.

The light detecting means 500 detects a tracking / focus error signal for the optical disc for DVD / CD by performing an operation on the light distribution of the light spot 600 formed by the diffraction beam incident through the optical means. As shown in Fig. 4, the first light detection region 510 detects the tracking / focusing error signal by the light distribution of the diffraction beam of red wavelength for DVD, and the light distribution of the diffraction beam of infrared wavelength for CD. And a second photodetection area 520 for detecting the tracking / focusing error signal.

Here, the first light detecting region 510 is formed on one side of the light detecting means 500, and from the first semiconductor chip 110 of the light emitting means 100 whose defocus is adjusted from the sensor lens 300. The first light detection pattern 511 and the second light detection are used to detect the tracking / focusing error signal of the optical disc for DVD using the light distribution of the light spot 700 by the diffracted beam of the red wavelength for the DVD. The pattern 512 and the third photodetection pattern 513 are formed.

Here, the first light detection pattern 511 is a place where the light spots 700 formed by the zeroth order diffraction beams are focused among the diffraction beams whose defocus is adjusted from the sensor lens 300, and (A) and (B) A photodetection pattern divided into four areas (C) and (D) is formed.

At this time, the region (A) and the region (C) are located on the diagonal, and the region (B) and the region (D) are located on the diagonal, among the four divided regions in which the first photodetection pattern 511 is formed.

In addition, the second photodetection pattern 512 is formed at a predetermined interval at an upper position of the first photodetection pattern 511 at a predetermined interval, and +1 of the diffraction beams in which defocus is adjusted from the sensor lens 300. The light spot 700 formed by the differential diffraction beam is focused, and a photodetection pattern divided into two regions (E1) and (E2) is formed.

In addition, the third photodetection pattern 513 is formed at a lower distance from the first photodetection pattern 511 at a predetermined interval, and is -1 in the diffraction beam whose defocus is adjusted from the sensor lens 300. The light spot 700 formed by the differential diffraction beam is focused, and a photodetection pattern divided into two regions (F1) and (F2) is formed.

The first light detection region 500 configured as described above is an O-order diffraction beam focused on the first light detection pattern 511 divided into four regions (A), (B), (C) and (D). The focusing error signal of the optical disc for DVD is detected using the following relation using the light distribution of the optical spot 700 formed by the following, that is, the following relation using astigmatism.

Focusing error signal (FES) = (A + C)-(B + D)

In addition, the first photodetection region 510 may include a light distribution of the light spot 700 formed by the zero-order diffraction beam focused on the first photodetection pattern 511, and a second and third photodetection pattern 512. For the DVD according to the following relationship using the light distribution of the light spot 700 formed by the ± 1st diffraction beam focused on each of the and 513, that is, the following relationship using the differential push-pull (DPP) method. The tracking error signal of the optical disc is detected.

Tracking error signal (TES) = (A + B)-(C + D) + k ((E2 + F2)-(E1 + F1)]

The second photodetection area 520 is formed on the other side of the photodetection means 500 spaced apart from the first photodetection area 510 by a predetermined interval, and defocused from the hologram 400. As a place for detecting the tracking / focusing error signal of the optical disc for CD using the light distribution of the optical spot 700 by the diffraction beam of the CD infrared wavelength emitted from the second semiconductor chip 120 of the light emitting means 100. And a fourth photodetection pattern 521, a fifth photodetection pattern 5220, and a sixth photodetection pattern 523.

Here, the fourth photodetection pattern 521 is a place where the light spots 700 formed by the 0th order diffraction beams are focused among the diffraction beams in which the defocus is adjusted from the hologram 400, (A), (B), A photodetection pattern divided into (C) and (D) regions is formed.

At this time, the (A) and (C) regions are located on the diagonal, and the (B) and (D) regions are located on the diagonal, among the four divided regions in which the fourth photodetection pattern 521 is formed.

In addition, the fifth photodetection pattern 522 is formed at a predetermined interval apart from each other at an upper position of the first photodetection pattern 521, and is + 1st order among the diffraction beams in which defocus is adjusted from the hologram 300. As the light spot 700 formed by the diffraction beam is focused, a light detection pattern divided into two regions (E1) and (E2) is formed.

In addition, the sixth photodetection pattern 523 is formed at a lower distance from the first photodetection pattern 521 at predetermined intervals, and is -1st order among the diffraction beams in which defocus is adjusted from the hologram 400. As the light spot 700 formed by the diffraction beam is focused, a photodetection pattern divided into two regions (F1) and (F2) is formed.

The second photodetection region 520 configured as described above is an order-order diffraction beam focused on a fourth photodetection pattern 521 divided into four regions (A), (B), (C), and (D). The focusing error signal of the optical disc for CD is detected by the following relation using the optical distribution of the optical spot 700 formed by the following, that is, the following relation using the split astigmatism.

Focusing error signal (FES) = (A + C)-(B + D)

In addition, the second photodetection region 520 may include a light distribution of the light spot 700 formed by the zeroth order diffraction beam focused on the fourth photodetection pattern 521, and the second and third photodetection patterns 522. CD according to the following relation using the light distribution of the light spot 700 formed by the ± 1st order diffracted beam focused at 523 and 523, that is, the following relation using the modified push-pull (MPP) method. The tracking error signal of the optical disc is detected.

Tracking error signal (TES) = (A + B)-(C + D) + k ((E2 + F2)-(E1 + F1)]

In this case, the fourth to sixth light detecting patterns 521, 522, and 523 have a wavelength of CD laser light emitted from the second semiconductor chip 120 of the light emitting unit 100 due to a change in temperature or the like. In the case of change, it has a structure extending in one direction to correspond to the change in the diffraction angle formed by the hologram 400 linked to the changed wavelength.

As described above, in the present invention, the laser light for DVD adjusts defocus through a sensor lens among laser light emitted through a light emitting means composed of a hybrid semiconductor chip, and the laser light for CD adjusts defocus through a hologram. By adjusting, not only can a DVD / CD combo type optical pickup device with a simple configuration and low manufacturing cost be realized, but also the effect of simultaneously performing tracking / focus servo tracking for optical discs for DVD and CD.

Herein, although the present invention has been described with reference to the preferred embodiments, those skilled in the art will variously modify the present invention without departing from the spirit and scope of the invention as set forth in the claims below. And be able to change.

1 is a view showing the configuration of a combo-type optical pickup device using a two-wavelength (2 Chips 1 Package) laser diode according to the present invention.

2 is a view showing a light detection pattern in which a light spot formed by a diffraction beam of a DVD optical disk whose defocus is adjusted through a sensor lens according to the present invention is focused;

3 is a view showing a light detection pattern in which a light spot formed by a diffraction beam of a CD optical disk whose defocus is adjusted through a hologram according to the present invention is focused;

4 is a diagram showing light detecting means in which a predetermined circuit pattern is formed in which a diffraction beam of a DVD / CD optical disc according to the present invention is focused;

Explanation of symbols on the main parts of the drawings

100 light emitting means 110 first semiconductor chip

120: second semiconductor chip 200: optical means

210: diffraction plate 220: beam splitter

230: collimator lens 240: wave plate

250: objective lens 300: sensor lens

400 hologram 500 light detection means

510: First photodetection area 511: First photodetection pattern

512: second photodetection pattern 513: third photodetection pattern

520: second photodetection region 521: fourth photodetection pattern

522: fifth photodetection pattern 523: sixth photodetection pattern

600: optical disk 700: optical spot

Claims (11)

Light emitting means for emitting two-wavelength laser light for tracking / focusing servo tracking of the optical disc; Optical means for focusing a diffraction beam formed by performing diffraction on the two-wavelength laser light on a track of an optical disc, and transmitting the diffraction beam reflected by the track to the outside; A sensor lens for adjusting defocus of an optical spot formed by a diffraction beam reflected from an optical disc for DVD among the diffraction beams incident through the optical means; A hologram for diffusing light spots formed by the diffraction beams reflected from the optical disc for CD among the diffraction beams incident through the optical means at a predetermined angle to adjust defocus; And A first light detection region focusing a light spot whose defocus is adjusted by the sensor lens, and a second light focusing a light spot whose focus is defocused by the hologram at a predetermined interval from the first light detection region Optical detection means for detecting a tracking / focusing error signal of the optical disc by using the light distribution of the optical spots configured to the detection area and focused on the first and second light detection areas Combo type optical pickup device, characterized in that configured to include. The method of claim 1, wherein the light emitting means, A combo type optical pickup device, wherein a first semiconductor chip that emits a laser light having a red wavelength for a DVD and a second semiconductor chip that emits a laser light having an infrared wavelength for a CD are packaged in a hybrid shape. The method of claim 1, wherein the optical means, A diffraction plate for diffraction of the two-wavelength laser light of the rectangular wave form emitted from the light emitting means to form a diffraction beam in the form of linearly polarized light; A beam splitter for branching a linearly polarized diffraction beam incident from the diffraction plate in an optical disk direction, and for diffracting a linearly diffracted beam incident from the optical disk in the direction of the sensor lens and the hologram; A collimator lens for converting a diffracted beam in the form of linearly flat light incident from the beam splitter into parallel light; A wavelength plate for converting the balanced light incident through the collimator lens into a circular flat diffraction beam and converting the circular flat diffraction beam reflected from the optical disk into a linear flat diffraction beam; And An objective lens for converging a circularly polarized diffraction beam incident from the wave plate to form a light spot having a predetermined shape at a track pitch of the optical disc Combo type optical pickup device comprising a. The method of claim 1, wherein the hologram, And a second hologram pattern having a different diffraction angle and a second hologram pattern in order to correspond to a change in a diffraction angle according to a wavelength change of a CD laser light incident from the optical means. The method of claim 1, wherein the first photodetection area of the photodetecting means, A first light detection pattern divided into four regions (A), (B), (C) and (D) in which a zeroth order diffraction beam is focused among the optical spots for DVD whose defocus is adjusted by the sensor lens; A second photodetection pattern formed in an upper direction of the first photodetection pattern and divided into two regions (E1) and (E2) where + first-order diffraction beams are focused;  A third photodetection pattern formed in a lower direction of the first photodetection pattern, and divided into two regions (F1) and (F2) where the -first-order diffraction beam is focused; (A) and (C) and (B) and (D) are each positioned on a diagonal line of the first photodetection pattern. The method according to claim 1 or 5, wherein the light detecting means, In the case where a zeroth order diffraction beam is focused on the first photodetection pattern with a predetermined light intensity distribution among the light spots for DVD, the following relational expression using astigmatism Focus error signal (FES) = (A + C)-(B + D) Combo type optical pickup device characterized in that for detecting the focus error signal using The method according to claim 1 or 5, wherein the light detecting means, Of the DVD light spots, a zeroth order diffraction beam is focused at a predetermined light intensity distribution on the first light detection pattern, and a ± first order diffraction beam is respectively at a predetermined light intensity distribution on the second and third light detection patterns. When focused, the following relation using differential push-pull method Tracking error signal (TES) = (A + B)-(C + D) + k ((E2 + F2)-(E1 + F1)] And a tracking error signal is detected using the Combo optical pickup device. The method of claim 1, wherein the second light detection region of the light detection means, A fourth light detection pattern divided into four regions (A), (B), (C) and (D) in which zeroth order diffraction beams are focused among CD light spots whose defocus is adjusted by the hologram, A fifth photodetection pattern formed in an upper direction of the fourth photodetection pattern and divided into two regions (E1) and (E2) where + first-order diffraction beams are focused;  A sixth photodetection pattern formed in the downward direction of the fourth photodetection pattern, and divided into two regions (F1) and (F2) where the -first-order diffraction beam is focused; The fourth to sixth light detection patterns have a structure extending in one direction in response to a change in the diffraction angle of the hologram according to the wavelength change of the light emitting means. The method according to claim 1 or 5, wherein the light detecting means, In the case where a zeroth order diffraction beam is focused on the first photodetection pattern with a predetermined light intensity distribution among the optical spots for CD, the following relational equation using the split astigmatism Focus error signal (FES) = (A + C)-(B + D) Combo type optical pickup device characterized in that for detecting the focus error signal using The method according to claim 1 or 5, wherein the light detecting means, Of the CD light spots, a zeroth order diffraction beam is focused at a predetermined light intensity distribution on the first light detection pattern, and a ± first order diffraction beam is respectively at a predetermined light intensity distribution on the second and third light detection patterns. When focused, the following relation using the modified push pull (MPP) method Tracking error signal (TES) = (A + B)-(C + D) + k ((E2 + F2)-(E1 + F1)] And a tracking error signal is detected using the Combo optical pickup device. The method of claim 1, And the light detecting means is a photodiode.