KR100655539B1 - Optical pickup - Google Patents

Abstract

The present invention discloses an optical pickup apparatus capable of detecting track control signals compatible with heterogeneous optical discs having different intervals between tracks.

The optical pickup apparatus according to the present invention includes a first divided region disposed at the center with a lattice pattern formed in a length of 90% to 110% of a width L2 suitable for the first type of optical disk by 1/2 pitch; The length of the first divided area, located at both sides of the first divided area and including the first divided area, is formed to be 90% to 110% of the objective lens radius L3, and is equal to 1/2 of the lattice pattern of the first divided area. 90% to 110 of the width L1 of the second divided region formed in the misaligned state and the length including the first divided region and the second divided region which are located on both sides of the second divided region and suitable for the second type of optical disk. A third division region formed in a length of% and deviated by a half pitch from the lattice pattern of the second division region so as to include at least zero order diffracted light and ± 1 for the beam emitted from the light source. A diffraction grating for generating the diffracted light is formed. The optical pickup device including the diffraction grating as described above can minimize the influence of the axis shift between the objective lens and the diffraction grating and obtain a good track control signal.

Optical pickup

Description

Optical pickup device {APPARATUS FOR OPTICAL PICK-UP}

1 is a view for explaining a conventional optical pickup device.

2 is a view for explaining the land / groove structure of the optical disc.

3 is a diagram illustrating a conventional push pull signal of a main beam and a sub beam;

4 is a diagram for explaining a conventional two-part diffraction grating.

FIG. 5 is a view for explaining that a sub-beam passing through a conventional two-part diffraction grating is formed on an optical disk. FIG.

Fig. 6 is a diagram showing the signal characteristics shown by the axis shift between the two-part diffraction grating and the objective lens in the DVD-RW.

Fig. 7 is a diagram showing the signal characteristics shown by the axis shift between the two-division diffraction grating and the objective lens in the DVD-RAM.

8 is a diagram for explaining a conventional multi-part diffraction grating.

9 illustrates an optical pickup apparatus according to the present invention.

10 is a view showing an embodiment of a diffraction grating in the present invention.

11 and 12 illustrate push pull signals of a DVD-RW and push pull signals of a DVD-RAM when the diffraction grating of the present invention is applied.

13 to 15 is another embodiment illustrating the diffraction grating of the present invention.

16 and 17 are diagrams for explaining a push pull signal of a DVD-RW and a push pull signal of a DVD-RAM when the diffraction grating of the present invention is applied.

<Explanation of symbols for main parts of drawing>

10; Light source 11; Collimator lens

12; Diffraction grating 13; Beam splitter

14; Quarter wave plate 15; Objective

16; Optical disc 17; Condenser

18; Cylindrical lens 19; Light detection means

20; Land 21; Groove

30; Diffraction grating 40; Multi-Diffraction Grating

90; Light source 91; Collimator lens

92; Diffraction grating 93; Beam splitter

94; Quarter wave plate 95; Objective

96; Optical disc 97; Condenser

98; Cylindrical lenses 99; Light detection means

100; Incident beams 192,292,393; Diffraction grating

110,210,310,410,510; First partition

120,220,320,420,520; 2nd partition

130,230,330,430; 3rd partition

340,440,540; First region 350,450,550; Second area

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical pickup apparatus, and more particularly, to an optical pickup apparatus capable of effectively detecting track control signals in a heterogeneous optical disc having different intervals between tracks.

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.

1 is a view for explaining a conventional optical pickup device.

As shown in FIG. 1, the conventional optical pickup apparatus includes a light source 10, a collimator lens 11, a diffraction grating 12, a beam splitter 13, and 1. The / 4 wave plate 14, the objective lens 15, the condenser lens 17, the cylindrical lens 18, and the light detecting means 19 are included.

The light source 10 emits a laser beam, and the collimator lens 11 converts the beam emitted from the light source 10 into parallel light.

The diffraction grating 12 generates at least zero-order diffraction light (main beam) and ± first-order diffraction light (sub-beam) from the beam passing through the collimator lens 11.

The beam splitter 13 transmits or reflects the incident beam according to the polarization direction of the beam incident by the light splitting means. For example, the beam incident on the diffraction grating 12 is transmitted, and the beam reflected by the optical disk 16 is reflected.

The light transmitted through the diffraction grating 12 is converted into circularly polarized light while passing through the quarter wave plate 14.

Then, the beam focused at the objective lens 15 and reflected at the optical disk 16 passes through the objective lens 15 and passes through the quarter wave plate 14 to change the polarization component.

Then, the light is reflected by the beam splitter 13 and passes through the condenser lens 17 and the cylindrical lens 18 and enters the light detecting means 19. The cylindrical lens 18 generates a boiling point for the incident beam to enable light detection.

On the other hand, a representative example of the optical disc 16 capable of recording or reproducing data through the optical pickup device is a DVD (Digital Versatile Disc). DVDs developed for recording include DVD-RW, DVD + Various specifications such as RW and DVD-RAM have been developed.

Such an optical disk has a land / groove structure as shown in FIG. 2.

The DVD-RW and the DVD + RW record data in the groove 21, whereas the DVD-RW and DVD + RW record data in the land 20 and the groove 21 in the case of the DVD-RAM.

On the other hand, there is a difference in the distance between the land 20 and the groove 21 according to the type of optical disk. For example, in the case of DVD + RW and DVD-RW, the distance between the land 20 and the land 20, that is, the value of the track pitch, which is one period in which data is recorded, is 0.74 mu m, and the land 20 ) And the groove 21 is 0.37㎛.

In the case of the DVD-RAM, the distance between the land 20 and the land 20 is 1.23 占 퐉, and since data is recorded in the land 20 and the groove 21, the track pitch is 0.615 占 퐉.

The optical pickup apparatus detects a control signal for ensuring that the beam focused by the objective lens 15 does not deviate from the center of the track while properly following the land 20 and the groove 21.

A widely used method of detecting a control signal is the DPP (Differential Push-Pull) method.

The DPP method divides the beam into three using the diffraction grating 12, and adjusts the subbeam to be arranged in the land 20 when the main beam is in the groove 21, thereby detecting the left and right signals of the light emitted from each beam. Use

In this case, each signal is referred to as a push-pull signal, and the signals of the main beam and the sub beam come out of a sine waveform having a phase of 180 degrees as shown in FIG. 3.

The difference between the two signals is called DPP. The reason for obtaining the difference signal between the main beam and the sub beam is to correct an error in the push-pull signal when the objective lens 15 is moved in the radial direction.

In the case of using the above DPP method, if the subbeam is in the groove 21, the main beam should be in the land 20, and if the subbeam is in the land 20, the main beam should be in the groove 21.

Therefore, compatibility with various types of optical discs with different track pitches such as DVD-RAM and DVD-RW is not easy.

In order to solve the above problems, a method of using a two-part diffraction grating has been proposed.

As shown in FIG. 4, the bipartite diffraction grating 30 has a shape in which a lattice pattern is shifted by a half pitch around the center.

The negative beam of ± 1st order light diffracted by the two-divided diffraction grating 30 has the same effect as the light transmitted through the phase plate having a phase difference of 180 degrees around the center. On the other hand, the main beam transmits as it is without phase difference.

In this case, when the beam passing through the objective lens is focused on the optical disk, a bimodal beam as shown in FIG. 5 is formed.

When the main beam is located in the groove and the double beam-shaped sub-beam center is also located in the groove, a push pull signal is obtained. The signal shown in FIG. 3 is represented.

In particular, since this signal is hardly affected by the track intervals such as DVD-RW and DVD-RAM, it can be detected compatible with various optical discs having different track intervals.

However, the center of the two-part diffraction grating and the center of the objective lens are not easily assembled by the assembly error.

Also, since the objective lens moves in the radial direction along the track of the optical disk, the center of the two-division diffraction grating and the center of the objective lens cannot be exactly coincident.

The phenomenon in which the center of the divided region of the diffraction grating and the center of the objective lens do not coincide is referred to as axial misalignment.

FIG. 6 is a diagram showing signal characteristics caused by an axis shift between a two-part diffraction grating and an objective lens in a DVD-RW, and FIG. 7 is an axis shift between a two-part diffraction grating and an objective lens in a DVD-RAM. It is a figure which shows the signal characteristic shown by. In the drawing, the solid line is the signal of the main beam and the dotted lines are the signals of the sub-beams which appear according to the degree of the axis shift.

As shown in the figure, the signal appearing as the axis is shifted in the DVD-RW is not large, but the signal appearing as the axis is shifted in the DVD-RAM can be seen that the magnitude of the shift is large.

Therefore, in order to obtain a more accurate push pull signal, the influence on the shaft misalignment should be minimized.

In order to minimize the influence on the axial misalignment as shown in FIG.

The multiplicity of diffraction gratings 40 is composed of a plurality of divided regions in which the patterns of the diffraction gratings are shifted by 1/2 pitch, respectively.

At this time, the width L of the divided region is calculated as follows.

Width (L) = (focal length of objective lens) / (track period of optical disc) * (wavelength of laser beam)

In the case of the DVD-RAM as an example, the width L is 1.637 mm when the focal length of the objective lens is 3.05 mm, the track period of the optical disk is 1.23 m, and the wavelength of the laser beam is 0.66 m.

However, the width (L) is based on the DVD-RAM, and in the case of the DVD-RW, there is a problem in that an influence due to the axis misalignment occurs.

An object of the present invention is to provide an optical pickup apparatus capable of detecting a stable DPP signal irrespective of the type of optical disk and the shaft shift.

An optical pickup apparatus according to the present invention comprises: a light source for emitting a beam; A first division region disposed in the center with a half-pitch of a lattice pattern formed in a length of 90% to 110% of a width L2 suitable for the first type of optical disk, and both sides of the first division region A second divided region formed at a length of 90% to 110% of the objective lens radius L3 and offset from the lattice pattern of the first divided region by 1/2 pitch. And a length including both the first divided area and the second divided area having a length of 90% to 110% of a width L1 suitable for the second type of optical disk, on both sides of the second divided area. A diffraction grating for generating at least zero-order diffraction light and ± first-order diffraction light with respect to the beam emitted from the light source by including at least a third division area formed by shifting the grid pattern of the two division area by 1/2 pitch Wow; A beam splitter for transmitting or reflecting the zeroth order diffracted light and the ± first order diffracted light; Condensing means for condensing the beam transmitted by the beam splitter on the optical disk; A cylindrical lens for generating a boiling point for the beam reflected from the optical disk; And light detection means for detecting the track control signal by the incident light having passed through the cylindrical lens.

More preferably, the width L2 of the partition area suitable for the first type of optical disc and the width L1 of the partition area suitable for the second type of optical disc are calculated by the following equation.

Width (L2) = (focal length of the objective lens) / (track period of the first optical disc) * (wavelength of the beam)

Width (L1) = (focal length of the objective lens) / (track period of the second optical disc) * (wavelength of the beam)

More preferably, the first type of optical disc is a DVD-RAM.

More preferably, the second type of optical disc is DVD-RW or DVD + RW.

More preferably, the beams passing through the plurality of divided regions each have a phase difference of 180 degrees with respect to the beams passing through the adjacent divided regions.

An optical pickup apparatus according to the present invention comprises: a light source for emitting a beam; A first division region having a width of 30% to 70% of the objective lens effective diameter and arranged in a state in which the lattice pattern is shifted by 1/2 pitch from the center, and positioned above and below the first division region, A lattice pattern having a length of 90% to 110% of the width L2 of the partition area suitable for the disk is disposed in the center of the first area and the adjacent area is disposed on both sides of the first area in a state of shifting by 1/2 pitch. A second division region including a second region and a third division region including at least one second region formed by shifting the first region and the lattice pattern by one-half pitch, thereby providing at least zero order diffracted light for the beam emitted from the light source; A diffraction grating for generating ± first order diffracted light; A beam splitter for transmitting or reflecting the zeroth order diffracted light and the ± first order diffracted light; Condensing means for condensing the beam transmitted by the beam splitter on the optical disk; A cylindrical lens for generating a boiling point for the beam reflected from the optical disk; And light detection means for detecting the track control signal by the incident light having passed through the cylindrical lens.

More preferably, the width L2 of the divided region suitable for the first type of optical disk is calculated by the following equation.

Width (L2) = (focal length of the objective lens) / (track period of the first optical disc) * (wavelength of the beam)

More preferably, the first type of optical disc is a DVD-RAM.

More preferably, the width of the first divided region is selected in the range of 1.2mm ~ 2.8mm.

More preferably, the beams passing through the first divided region and the first region positioned above and below the first divided region have the same phase.

More preferably, the beam passing through the second region located above the first divided region and the first divided region has a phase difference of 180 degrees.

More preferably, the beam passing through the first divided region and the second region located above and below the first divided region has a phase difference of 180 degrees.

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

9 is a view for explaining an optical pickup device according to the present invention.

9, an optical pickup apparatus according to the present invention includes a light source 90, a collimator lens 91, a diffraction grating 92, a beam splitter 93, and 1. The / 4 wave plate 94, the objective lens 95, the condenser lens 97, the cylindrical lens 98, and the light detecting means 99 are included.

The light source 90 emits a laser beam, and the collimator lens 91 converts the beam emitted from the light source 90 into parallel light.

The diffraction grating 92 generates at least zero-order diffraction light (main beam) and ± first-order diffraction light (sub beam) from the beam passing through the collimator lens 91.

In particular, in the present invention, the diffraction grating 92 is formed in multiple divisions, and each adjacent divided region is formed with a misaligned grating pattern.

The beam splitter 93 transmits or reflects the incident beam according to the polarization direction of the beam incident by the light splitting means. For example, the beam incident on the diffraction grating 92 is transmitted, and the beam reflected by the optical disk 96 is reflected.

The light transmitted through the diffraction grating 92 is converted into circularly polarized light while passing through the quarter wave plate 94.

The beam focused at the objective lens 95 and reflected at the optical disk 96 passes through the objective lens 95 and passes through the quarter wave plate 94 to change the polarization component.

The light is reflected by the beam splitter 93 and passes through the condenser lens 97 and the cylindrical lens 98 and enters the light detecting means 99. The cylindrical lens 98 generates a boiling point for the incident beam to enable light detection.

On the other hand, as shown in Figure 10, the diffraction grating 92 is composed of a multi-divided, the grating pattern of the adjacent divided region is formed to be offset by each other by 1/2 pitch so that the beam passing through the adjacent divided region of 180 degrees It will have a phase difference. In FIG. 10, reference numeral 100 denotes an incident beam incident on the diffraction grating 92.

As described above, the width L of the divided region of the diffraction grating insensitive to the axial shift phenomenon of the objective lens and the diffraction grating can be obtained as follows.

Width (L) = (focal length of objective lens) / (track period of optical disc) * (wavelength of laser beam)

In the case of a DVD-RAM, the width L is 1.637 mm when the focal length of the objective lens is 3.05 mm, the track period of the optical disk is 1.23 m, and the wavelength of the laser beam is 0.66 m.

However, if the width of the divided area is set to 1.637 mm, the DVD-RW becomes susceptible to axial distortion.

Calculating the width (L) of the divided region suitable for the DVD-RW, the width (L) is 2.72mm when the focal length of the objective lens is 3.05 mm, the track period of the optical disk is 0.74 µm, and the wavelength of the laser beam is 0.66 µm. do.

If the width L of the divided region is set to 2.72 mm suitable for the DVD-RW, the radius of the objective lens is 2.0 mm, which is smaller than the width L of the divided region, so that it does not have a meaning of multi-division. In other words, the result is the same as the actual two-part diffraction grating. On the other hand, DVD-RAM has a large influence due to the shaft misalignment.

Accordingly, the present invention proposes the width of the divided region of the multi-diffraction grating suitable for multiple optical discs having different track spacing.

That is, the width L of the partition area for minimizing the axis shift phenomenon for a plurality of optical disks is the width L1 of the partition area suitable for DVD-RW (or DVD + RW) and the partition area suitable for DVD-RAM. Can be calculated by the relationship between the width L2 and the radius L3 of the objective lens.

For example, if the width L1 of the partition area suitable for DVD-RW is 2.72 mm, the width L2 of the partition area suitable for DVD-RAM is 1.637 mm, and the radius L3 of the objective lens is 2.0 mm. Partitions suitable for both -RW and DVD-RAM can be presented as shown in FIG.

That is, at least the first divided regions 110 and 210, the second divided regions 120 and 220, and the third divided regions 130 and 230 are formed based on the center of the diffraction grating 92.

First, the first divided regions 110 and 210 are located at both sides of the center of the diffraction grating 92, and the lattice patterns of the divided regions are formed to be offset from each other by 1/2 pitch. Therefore, the beam passing through the first divided regions 110 and 210 with respect to the center of the diffraction grating 92 has a phase difference of 180 degrees.

The length from the center of the diffraction grating 92 to the end of the first divided region 110 is formed by the width L2 of the divided region suitable for the DVD-RAM.

The second divided regions 120 and 220 are positioned outside the first divided regions 110 and 210, and are formed to be offset by a half pitch from the lattice pattern of the adjacent first divided regions 110 and 210. The beams passing through the second divided regions 120 and 220 have a phase difference of 180 degrees with each other.

The length from the center of the diffraction grating 92 to the ends of the second divided regions 120 and 220 is formed as the length L3 of the radius of the objective lens.

The third divided regions 130 and 230 are located outside the second divided regions 120 and 220, and are offset by a half pitch from the lattice pattern of the adjacent second divided regions 120 and 220. Formed. The beams passing through the third divided regions 130 and 230 have a phase difference of 180 degrees with each other.

The length from the center of the diffraction grating 92 to the end of the third divided regions 130 and 230 is formed as the width L1 of the divided region suitable for the DVD-RW.

That is, each divided region is formed to be shifted by 1/2 pitch from the grid pattern of the adjacent divided region, and the beams passing through the adjacent divided region have a phase difference of 180 degrees from each other.

According to experimental results, the length from the center of the diffraction grating 92 to the end of the first divided regions 110 and 210 is 90% to 110 of the width L2 of the divided region suitable for the DVD-RAM. It is preferably formed in the% range.

In addition, the length from the center of the diffraction grating 92 to the end of the second divided region 120, 220 is preferably formed in the range of 90% to 110% of the length (L3) of the radius of the objective lens. Do.

In addition, the length from the center of the diffraction grating 92 to the ends of the third divided regions 130 and 230 is formed within 90% to 110% of the width L1 of the divided region suitable for the DVD-RW. It is desirable to be.

That is, when the width of the divided region of the multi-diffraction grating is within the above range, a more accurate push pull signal can be obtained while minimizing the axis shift phenomenon for the DVD-RW and the DVD-RAM.

The above embodiment takes DVD-RW as an example, but the same effect can be obtained in the case of DVD + RW and DVD-RAM.

As such, when the multi-part diffraction grating is formed, a push pull signal as illustrated in FIGS. 11 and 12 may be detected.

11 is a push pull signal of a DVD-RW, and FIG. 12 is a push pull signal of a DVD-RAM.

As shown in Figs. 11 and 12, as a result of the application of the multi-part diffraction grating of the present invention, it is possible to obtain a good push pull signal without distorting phenomena in heterogeneous optical discs having different track periods.

In particular, looking at the push pull signal according to the degree of the axis shift for the DVD-RW of Figure 11 it can be seen that the amount of change in the push pull signal for the axis shift.

13 is a view for explaining another embodiment of the diffraction grating in the present invention.

Referring to FIG. 13, the diffraction grating 192 includes at least a first divided region 310, a second divided region 320, and a third divided region 330.

The first divided region 310 is formed to be shifted by 1/2 pitch with respect to the center of the diffraction grating 192, and extends from the center of the diffraction grating 192 to both ends.

Therefore, the beam passing through the first divided region 310 has a phase difference of 180 degrees with respect to the center of the diffraction grating 192.

The width of the first divided area 310 is selected to a value in the range of 30% to 70% of the effective lens effective diameter. Therefore, when the effective diameter of the objective lens is 4.0mm, it has a value of 1.2mm to 2.8mm.

Meanwhile, the second divided region 320 and the third divided region 330 are positioned above and below the first divided region 310.

The second divided region 320 and the third divided region 330 are located at both sides of the center of the diffraction grating 192 and have a lattice pattern deviated from each other by a half pitch and the first region 340. A second region 350 is disposed on both sides of the region 340 and has a lattice pattern formed to be shifted by a half pitch from the lattice pattern of the adjacent first region 340.

The length from the center of the diffraction grating 192 to the end of the first region 340 is formed as the width L2 of the divided region suitable for the DVD-RAM.

According to experimental results, the length from the center of the diffraction grating 192 to the end of the first region 340 is formed within the range of 90% to 110% of the width L2 of the partition region suitable for the DVD-RAM. It is desirable to be.

The beam passing through the first region 340 has a phase difference of about 180 degrees with respect to the center of the diffraction grating 192, and the second region 350 positioned at both sides of the first region 340 is formed in the first region 340. There is a phase difference of 180 degrees with respect to the beam passing through one region 340.

In addition, the beams passing through the first divided region 310 and the first region 340 positioned above and below the first divided region 310 have the same phase, and the first divided region 310 and the first divided region. The beam passing through the second region 350 positioned above and below the one division region 310 has a phase difference of 180 degrees.

14 and 15 show an embodiment similar to the embodiment described with reference to FIG. 13.

The diffraction gratings 292 and 392 include at least a first divided area 410 and 510, a second divided area 420 and 520, and a third divided area 430 and 530.

The first divided regions 410 and 510 are formed to be shifted by 1/2 pitch based on the centers of the diffraction gratings 292 and 392 and extend from the center of the diffraction gratings 292 and 392 to both ends. do.

Therefore, the beam passing through the first divided regions 410 and 510 has a phase difference of 180 degrees with respect to the center of the diffraction gratings 292 and 392.

The width of the first divided regions 410 and 510 is selected to a value ranging from 30% to 70% of the effective lens effective diameter. Therefore, when the effective diameter of the objective lens is 4.0mm, it has a value of 1.2mm to 2.8mm.

Meanwhile, the second divided regions 420 and 520 and the third divided regions 430 and 530 are positioned above and below the first divided regions 410 and 510.

The second divided regions 420, 520 and the third divided regions 430 and 530 are disposed on both sides of the center of the diffraction gratings 292 and 392, and the lattice patterns are formed to be offset from each other by 1/2 pitch. A second lattice pattern positioned at both sides of the first region 440 and 540 and the first region 440 and 540 and offset by a half pitch from the lattice pattern of the adjacent first regions 440 and 540. Regions 450 and 550 are included.

The length from the center of the diffraction gratings 292 and 392 to the ends of the first regions 440 and 540 is formed as the width L2 of the partition region suitable for the DVD-RAM.

Experimental results show that the length from the center of the diffraction gratings 292 and 392 to the ends of the first regions 440 and 540 is 90% of the width L2 of the divided region suitable for the DVD-RAM. It is preferably formed in the range of ˜110%.

14 and 15, the beam passing through the first regions 440 and 540 has a phase difference of 180 degrees with respect to the center of the diffraction gratings 292 and 392, and the first region 440 ( The second regions 450 and 550 positioned at both sides of the 540 have a phase difference of 180 degrees with respect to the beam passing through the first regions 440 and 540.

In addition, in FIG. 14, the beam passing through the first divided region 410 and the second region 450 located above the first divided region 410 has the same phase and the first divided region 410. And a beam passing through the second region 450 positioned below the first divided region 410 has a phase difference of 180 degrees.

In addition, the beams passing through the first divided region 510 and the second region 550 located above and below the first divided region 510 in FIG. 15 have the same phase, and the first divided region 510. And a beam passing through the first region 540 positioned above and below the first divided region 510 has a phase difference of 180 degrees.

14 and 15 have the same basic principle as the embodiment described with reference to FIG. 13, but there are differences in regions where the lattice patterns are shifted.

FIG. 16 is a push pull signal of a DVD-RW to which the diffraction grating described in FIGS. 13 to 15 is applied, and FIG. 17 is a push pull signal of a DVD-RAM.

As shown in FIG. 16 and FIG. 17, it can be seen that as a result of applying the diffraction grating according to the embodiment of the present invention, a good push pull signal can be obtained in a heterogeneous optical disc having different track periods without axial shift. have.

The present invention has the advantage of being able to detect a good track control signal in a wide variety of optical discs without axial shift.

Claims (12)

A light source emitting a beam; A first division region disposed in the center with a half-pitch of a lattice pattern formed in a length of 90% to 110% of a width L2 suitable for the first type of optical disk, and both sides of the first division region A second divided region formed at a length of 90% to 110% of the objective lens radius L3 and offset from the lattice pattern of the first divided region by 1/2 pitch. And a length including both the first divided area and the second divided area having a length of 90% to 110% of a width L1 suitable for the second type of optical disk, on both sides of the second divided area. A diffraction grating for generating at least zero-order diffraction light and ± first-order diffraction light with respect to the beam emitted from the light source by including at least a third division area formed by shifting the grid pattern of the two division area by 1/2 pitch Wow; A beam splitter for transmitting or reflecting the zeroth order diffracted light and the ± first order diffracted light; Condensing means for condensing the beam transmitted by the beam splitter on the optical disk; A cylindrical lens for generating a boiling point for the beam reflected from the optical disk; Light detecting means for detecting the track control signal by the incident light passing through the cylindrical lens; And the width L2 of the partition area suitable for the first type of optical disc and the width L1 of the partition area suitable for the second type of optical disc are calculated by the following equation. Width (L2) = (focal length of the objective lens) / (track period of the first optical disc) * (wavelength of the beam) Width (L1) = (focal length of the objective lens) / (track period of the second optical disc) * (wavelength of the beam) delete The method of claim 1, And said first type of optical disc is a DVD-RAM. The method of claim 1, And said second type of optical disc is a DVD-RW or a DVD + RW. The method of claim 1, And the beams passing through the plurality of divided regions each have a phase difference of 180 degrees with respect to the beams passing through the adjacent divided regions. A light source emitting a beam; A first division region having a width of 30% to 70% of the objective lens effective diameter and arranged in a state in which the lattice pattern is shifted by 1/2 pitch from the center, and positioned above and below the first division region, A lattice pattern having a length of 90% to 110% of the width L2 of the partition area suitable for the disk is disposed in the center of the first area and the adjacent area is disposed on both sides of the first area in a state of shifting by 1/2 pitch. A second division region including a second region and a third division region including at least one second region formed by shifting the first region and the lattice pattern by one-half pitch, thereby providing at least zero order diffracted light for the beam emitted from the light source; A diffraction grating for generating ± first order diffracted light; A beam splitter for transmitting or reflecting the zeroth order diffracted light and the ± first order diffracted light; Condensing means for condensing the beam transmitted by the beam splitter on the optical disk; A cylindrical lens for generating a boiling point for the beam reflected from the optical disk; And light detecting means for detecting the track control signal by the incident light passing through the cylindrical lens, wherein the width L2 of the divided region suitable for the first type of optical disk is calculated by the following equation. Optical pickup device. Width (L2) = (focal length of the objective lens) / (track period of the first optical disc) * (wavelength of the beam) delete The method of claim 6, And said first type of optical disc is a DVD-RAM. The method of claim 6, The width of the first divided region is selected in the range of 1.2mm ~ 2.8mm optical pickup device. The method of claim 6, And a beam passing through a first region located above and below the first divided region and the first divided region has the same phase. The method of claim 6, And the beam passing through the first divided region and the second region located above the first divided region has a phase difference of 180 degrees. The method of claim 6, And a beam passing through the first divided region and the second region located above and below the first divided region has a phase difference of 180 degrees.

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