KR20100110142A - Signal devisioin method, pickup and recording/reproducing apparatus - Google Patents

Abstract

PURPOSE: A signal division method, an optical pickup unit, and a recording/reproducing apparatus are provided to improve optical efficiency and reduce the size of a recording/reproducing system by reducing the number of parts for splitting polarized light. CONSTITUTION: An optical pickup unit(100) comprises a first division combiner(30) and a detection unit(70a,70b). The first division combiner receives polarized light reflected from a second division combiner(40) and passes a part of the light while reflecting the rest. The second division combiner passes only the light of specific polarizing direction. The detection unit generates a gap error signal corresponding to the polarized light passing through the first division combiner or the polarized light reflected to the first division combiner.

Description

SIGNAL DEVISIOIN METHOD, PICKUP AND RECORDING / REPRODUCING APPARATUS}

The present invention relates to a method for separating signals using reflected light, and an optical pickup and recording / reproducing apparatus.

A recording / reproducing apparatus using light records data on the recording medium or reproduces the recorded data by using a recording medium such as various disk types. Recently, high-quality video processing is required due to the advancement of consumer's preference, and as the video compression technology is developed, the recording medium is also required to be high in density. To this end, as a technology for high-density recording media, recently, near-field optical recording by near-field optics such as Blue-ray Disc, HD-DVD, etc., which uses short-wavelength blue light Recording, NFR) devices are being developed. In addition, a recording medium having a multilayer recording layer has been developed.

The NFR device applies a SIL (Soiled Immersion Lens, hereinafter referred to as SIL) in addition to the objective lens of the optical unit to record and reproduce by increasing the NA (aperture number). This NFR method is a Gap Servo Controller that records the SIL of the pickup and the Gap of the media while maintaining tens of nanometers. In the NFR method, the distance between the SIL and the media, the size of the beam reaching the disk, and the recording characteristics of the particular pulse determine the performance of the recording and reproducing apparatus.

The present invention aims to improve the light efficiency, reduce the size of the recording / reproducing system, and reduce the system construction cost by reducing the number of components for separating polarized light.

The signal separation method according to the present invention for achieving the above object is reflected by the second separation synthesis section without passing through the second separation synthesis section that passes only the polarization in a specific direction according to the polarization direction of the light reflected from the recording medium. The first step of receiving the undistorted polarized light formed, the second step of passing through the partial region of the polarization received from the second separation synthesis unit, and reflecting and separating the remaining region and corresponding to the partial region or the remaining region A third step of generating a gap error signal GES may be included.

The signal may be separated using the divergence angle difference from the recording medium or the near field forming lens in the partial region and the remaining region, or may be separated using the position of the aperture.

In addition, another signal separation method according to the present invention for achieving the above object does not pass through the second separation synthesis section passing only the polarization in a specific direction in accordance with the polarization direction of the light reflected from the recording medium, the second separation synthesis A first step of receiving undistorted polarized light formed by reflection from the second unit, and generating a gap error signal GES and a recording / reproducing signal RF by using the undistorted polarized light received from the second separation synthesis unit. It may include two steps.

Here, the signal may be separated using the divergence angle difference from the recording medium or the near-field forming lens of each region in the undistorted polarized light.

On the other hand, the optical pickup according to the present invention for achieving the above object does not pass through the second separation synthesis section that passes only the polarization in a specific direction according to the polarization direction of the light reflected from the recording medium, and is reflected by the second separation synthesis section. And receive the non-distorted polarized light, which is passed through some of the areas, and reflects and separates the remaining areas, and the polarized light passing through the first separation compound or the reflection from the first separation compound. It may include a detector for generating a gap error signal (GES) corresponding to the polarized light.

The optical pickup may further include a lens that allows the respective regions to form different focal lengths by the divergence angle difference from the recording medium or the near field forming lens of the partial region and the remaining region.

In addition, another optical pickup according to the present invention for achieving the above object does not pass through the second separation synthesis section for passing only the polarization in a specific direction according to the polarization direction of the light reflected from the recording medium, the second separation synthesis section And a detection unit generating a gap error signal GES and a recording / reproducing signal RF using the non-distorted polarized light received from the lens and the non-distorted polarized light received from the lens.

The lens can cause the respective areas to form different focal lengths by the divergence angle difference from the recording medium or the near field forming lens of each area in the undistorted polarized light.

The detection unit may include a plurality of light receiving cells composed of one or multi-division regions, and the gap error signal GES and the recording / reproducing signal RF using the sum of the amounts of light between the multi-division regions or the light receiving cells. Can be generated.

Finally, the recording / reproducing apparatus according to the present invention does not pass through the second separation synthesis portion that passes only the polarization in a specific direction according to the polarization direction of the light reflected from the recording medium, and is reflected by the second separation synthesis portion. It may include an optical pickup that receives the unpolarized polarization, passes some areas of the light, and reflects and separates the remaining areas, and a controller for controlling the optical pickup to record data to or reproduce the recorded data on a recording medium. .

According to the signal separation method, the optical pickup, and the recording and reproducing apparatus according to the present invention, by reducing the number of parts for separating polarized light, the optical efficiency can be improved, the size of the recording and reproducing system can be reduced, and the system construction cost can be reduced. .

Hereinafter, an embodiment of the method and apparatus for controlling intervals constituting the present invention will be described in detail. In adding reference numerals to the components of the following drawings, the same components are used the same reference numerals as much as possible even if they are displayed on different drawings. In this specification, for convenience of description, an example of a recording method and apparatus will be described in detail.

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 term " recording / reproducing device " means all devices capable of recording or reproducing data using the above-described recording medium and all devices capable of recording and reproducing. In addition, the "recording reproduction method" means a method of recording or reproducing data. In the present specification, a recording and reproducing apparatus using a near field is described as an example for convenience of description, but the present invention is not limited thereto.

DETAILED DESCRIPTION Hereinafter, exemplary 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 present invention.

1 is a schematic diagram of a recording / reproducing apparatus according to an embodiment of the present invention. The recording / reproducing apparatus detects light reflected from the optical pickup 100 and reflected on the recording medium 200, and controls the tilting or tracking of the track according to the detected light so that the light is irradiated at the correct position. do. Hereinafter, the optical system included in the optical pickup 100 will be described in detail.

The optical pickup 100 includes a light source 10, and the light source 10 may be a laser having good directivity, such as a laser diode. The light irradiated from the light source 10 onto the recording medium may be parallel light. Therefore, the recording and reproducing apparatus according to the embodiment of the present invention includes a collimate lens 20 for paralleling the path of the light emitted from the light source 10.

The separation and synthesis units 30 and 40 separate paths of light incident in the same direction or synthesize paths of light incident in different directions. The data recording and reproducing apparatus according to the present embodiment includes a first separating synthesis unit 30 and a second separating synthesis unit 40.

The first separation composition part 30 is the incident light of Passes some and reflects some. For example, the first separation synthesis unit 30 may be a non-polarized beam splitter (NBS). The second separation synthesis unit 40 may be a polarized beam splitter (PBS) that passes only polarization in a specific direction according to the polarization direction. When the linear polarization is used, the second separation composition part 40 may be configured to pass only the polarization component in the vertical direction and reflect the polarization component in the horizontal direction. The component may be configured to reflect.

The lens unit 50 is positioned close to the recording medium 200 to irradiate light to a predetermined area of the recording medium 200.

2 is a schematic diagram showing the configuration of the lens unit 50. As shown in FIG. 2, in the present embodiment, the lens unit 50 includes a near field forming lens provided on a path through which the light passing through the objective lens 52 and the objective lens 52 enters the recording medium 100. 54). In this manner, the near field forming lens 54 having a high refractive index other than the objective lens 52 is provided so that the numerical aperture of the lens portion 50 is increased and dissipated waves are formed. The near field forming lens 54 may use a solid immersion lens (SIL).

As shown, the near field forming lens 54 may be hemispherical formed by cutting a spherical lens. Alternatively, the near field forming lens may be made of an ultra hemispherical shape which is part of a sphere having a middle height between a sphere and a hemisphere. In this case, the lens unit 50 is located very close to the recording medium 200. When the near field forming lens 54 and the recording medium 200 are brought close to about 1/4 or less of the optical wavelength (that is, λ / 4), the dissipated wave generated inside the lens unit 50 retains its properties. Therefore, the dissipation wave can be used for recording and reproducing. However, when the distance between the near field forming lens 54 and the recording medium 200 is greater than λ / 4 or more, the wavelength of the light loses the property of the dissipated wave and returns to the original wavelength. Therefore, in the recording / reproducing apparatus using the near field, the distance between the lens unit 50 and the recording medium 200 does not exceed approximately λ / 4. Where λ / 4 is the limit of the near field.

In the present exemplary embodiment, the light conversion surface 60 is provided between the lens unit 50 and the second separation compound unit 40. The light conversion surface 60 converts the polarization directions of the light incident on the recording medium 200 and the reflected light. When the light conversion surface 60 is a quarter wave plate, the light conversion surface 60 circularly polarizes the light incident on the recording medium 200 and reflects the light reflected from the recording medium 200. Polarize right. As a result, the reflected light passing through the light conversion surface 60 is converted in the polarization direction in a direction different from the incident light, and has a phase difference of 90 degrees with each other.

The detection unit 70 receives the reflected light and generates an electric signal corresponding thereto, thereby generating an electric signal corresponding to the recording and reproducing signal RF, and an electric signal corresponding to the gap error signal GES. It may include a second detector 70b for generating a. In addition, the case where the optical pickup 100 is inclined relative to the recording medium 200 is called a tilt for convenience, and the tilt is a radial direction or a tangent to the track direction of the recording medium 200. It can occur in the (Tangential) direction or it can contain both components. The detector 70 may generate an electrical signal corresponding to the tilt error signal TE as shown in FIG. 4.

Obviously, the first detector 70a and the second detector 70b may be provided in various embodiments. Each of the first detector 70a or the second detector 70b may include at least one light receiving cell. In addition, each light receiving cell may include a multi-division region. For example, the detection unit 70 may include two light receiving cells, and each light receiving cell may be configured by two or four division regions, which will be described later.

In the case of the present invention, the reflected light whose polarization direction is converted does not pass through the second separation combining unit 40 through which the incident light passes and is reflected to enter the first separation combining unit 30. The loss of light reaching the recording medium 200 may be minimized by not using the NBS, which is the first separation and synthesis unit 30, on the path of the light incident from the light source 10 to the recording medium 200 (not shown). have. The first separation synthesis unit 30 positioned in the path where the light is reflected from the recording medium 200, rather than the path of light incident from the light source 10 to the recording medium 200, is reflected by the second separation synthesis unit 40. And receive undistorted polarization, which passes through some of the areas, reflects the remaining areas, and separates them.

For example, some regions of polarized light may be passed through the first lens 65a of FIG. 1, and the remaining regions may be reflected and separated by the second lens 65b. As shown in FIG. 1, when all of the polarized light passes through both the first and second synthesizing parts 30 and passes through both the first lens 65a and the second lens 65b, the aperture is used as an aperture. The path of the light can be adjusted.

If all parts of the polarized light intend to reach the first detection unit 70a after passing through the first separation compound unit 30 and the first lens 65a, the apertures b and c are shown as shown. The light for only the recording / reproducing signal RF arrives at the first detection unit 70a, and the light for the gap error signal GES is blocked. Similarly, when all parts of the polarized light are to reach the second detection unit 70b through the first separation compound 30 and the second lens 65b, the aperture a is used as shown. Only the light for the gap error signal GES arrives at the second detection unit 70b, and the light for the recording / playback signal RF is blocked.

In addition, the lenses 65a and 65b may separate the polarized light by causing the respective areas to form different focal lengths by the divergence angle difference from the recording medium 200 or the near field forming lens 54 of the respective partial areas of the polarized light. .

For example, as shown in FIG. 3B, when the recording medium 200 is a cover layer disc, some of the incident light incident on the recording medium 200 is reflected on the surface of the recording medium 200, and a part of the recording medium 200 is reflected. Is reflected at the surface of the near field forming lens 54. This is different from when all of the incident light incident on the recording medium 200 is reflected on the surface of the near field forming lens 54 when the recording medium 200 shown in FIG. 3A is a first surface disc. That is, the reflected light for the recording / reproducing signal RF forms a focus on the surface of the recording medium 200 and is reflected as parallel light, while the reflected light for the gap error signal GES is reflected on the surface of the near field forming lens 54. It forms a focal point and reflects and diverges. Accordingly, the reflected light for the recording / reproducing signal RF and the reflected light for the gap error signal GES form different divergence angles, and each reflected light is separately separated by using each reflected light having a different focal length. Can be detected.

 The first detection unit 70a and the second detection unit 70b respectively input the recording and reproducing signal RF and the gap error signal GES detected separately to the control unit 90. 4, the detector 70 inputs the detected tilt error signal TE to the controller 90.

The controller 90 receives the signal detected by the detector 70 and controls the optical pickup 100. For example, the gap between the optical pickup 100 and the recording medium 200 is controlled by using a gap error signal GES, and the optical pickup 100 is recorded by using a tilt error signal TE. Control the tilt for medium 200.

Meanwhile, the main controller 300 may be connected to the recording and reproducing apparatus to form a data recording and reproducing system. The main control unit 300 controls the control unit 90 of the recording / playback apparatus. The main controller 300 transmits a recording or reproducing command to the control unit 90 through the interface, receives the reproduced data from the recording and reproducing apparatus, and transmits data to be recorded to the recording and reproducing apparatus. Meanwhile, the main controller 300 may directly control the lens unit 50 by receiving a signal from the first detector 70a and the second detector 70b. In this case, the main controller 300 may be a main controller of a PC, a server, an audio device, or a video device.

4 is a schematic diagram of a recording / reproducing apparatus according to another embodiment of the present invention.

Regarding the light sources 10, the collimate lens 20, the separation synthesis unit 40, the lens unit 50, the light conversion surface 60, and the main control unit 300, which are components of FIG. 4, As described above.

The lens 65 is formed by being reflected by the second separation composition portion 40 without passing through the second separation composition portion 40 that passes only polarization in a specific direction according to the polarization direction of the light reflected from the recording medium 200. The non-distorted polarized light is received and transmitted to the detector 70. As described above, the lens 65 can cause the respective regions to form different focal lengths by the divergence angle difference from the recording medium 200 or the near field forming lens 54 in each region in the undistorted polarization. .

The detector 70 generates a gap error signal GES and a recording / playback signal RF using the undistorted polarization received from the lens 65, and generates a tilt control signal TE in addition to the controller 90. To send. Various combinations of the gap error signal GES, the recording / reproducing signal RF, and the tilt control signal TE detected by the detection unit 70 will be described later.

5 is a diagram illustrating a configuration of light receiving cells in the detector 70 of FIG. 4 according to an exemplary embodiment of the present invention.

As illustrated in FIG. 5, a case in which the detector 70 includes three light receiving cells 215, 225, and 235 is described as an example, but is not limited thereto. For convenience of explanation, the divided regions of the light receiving cells in the detection unit 70 are indicated by symbols. That is, the upper and lower regions of the first light receiving cell 215 are named e and f in order, and the four divided regions of the second light receiving cell 225 are named a, b, c and d in the clockwise direction. In addition, the upper and lower regions of the third light receiving cell 235 are named g and h in order. The symbols for distinguishing each divided region, a, b, c, d, e, f, g, and h may refer to the amount of light received in the corresponding region. In the case of a signal for checking whether the recording medium 200 and the optical pickup 100 are tilted, specifically, a radial tilt signal in a radial direction, an upper region of the first light receiving cell 215 and the third light receiving cell 235 Derived using the difference of the values in the lower region. That is, the radial tilt error signal is derived from the value (e + g)-(f + h). If the sum of the amounts of light in the upper region and the sum of the amounts of light in the lower region are the same in the radial direction, it may be determined that no tilt occurs in the radial direction. It is apparent that the present invention is not limited to the radial tilt error signal, and is applicable to the calculation of the tangential tilt error signal in the same manner. Subsequently, in the case of the tangential tilt error signal indicating the degree of inclination in the tangential direction, it is derived using the values of (a + d)-(b + c) of the second light receiving cell 225. Since the gap error signal GES is the sum of the amounts of light received by the detector 70, the gap error signal GES is derived by using a + b + c + d + e + f + g + h values. The signal value for the DC offset compensation of the tracking error signal is also derived from the values (a + b + e + g)-(c + d + f + h). Finally, the hatched areas inside a, b, c, and d become the amount of light for the recording / reproducing signal RF.

6 illustrates the configuration of light receiving cells in the detector 70 according to another embodiment of the present invention. In the case of a tangential tilt error signal, it is derived from the value of (A + C)-(B + D), in the case of the radial tilt error signal, it is derived from the value of EF, and in the case of the gap error signal (GES). Derived using the value of B + C + D + E + F, the signal value for the DC offset compensation of the tracking error signal can be derived as (A + B + E)-(C + D + F). Finally, the hatched areas inside A, B, C, and D become the amount of light for the recording / reproducing signal RF.

1 is a schematic diagram of a recording / reproducing apparatus according to an embodiment of the present invention;

2 is a schematic view showing the configuration of the lens unit 50.

3A is a schematic diagram of an optical path when the recording medium 200 is a first surface disc.

3B is a schematic diagram of an optical path when the recording medium 200 is a cover layer disc.

4 is a schematic diagram of a recording / reproducing apparatus according to another embodiment of the present invention;

5 is a schematic diagram showing the configuration of light receiving cells in the detector 70 of FIG. 4 according to an embodiment of the present invention.

Figure 6 is a schematic diagram showing the configuration of the light receiving cells in the detector 70 according to another embodiment of the present invention.

Claims (11)

A first step of receiving undistorted polarized light reflected by the second separated synthesized portion without passing through the second separated synthesized portion passing only the polarization in a specific direction according to the polarization direction of the light reflected from the recording medium; A second step of passing a portion of polarized light received from the second separation synthesis unit and reflecting and separating the remaining region; And And generating a gap error signal (GES) corresponding to the partial region or the remaining region. The method of claim 1, The second step, And a divergence angle difference from the recording medium or the near field forming lens in the partial region and the remaining region. The method of claim 1, The second step, The signal separation method is a step of separating using the position of the aperture. A first step of receiving undistorted polarized light reflected by the second separated synthesis portion without passing through the second separated synthesis portion passing only the polarization in a specific direction according to the polarization direction of the light reflected from the recording medium; And And generating a gap error signal (GES) and a recording / playback signal (RF) by using the undistorted polarized light received from the second separation synthesizer. The method of claim 4, wherein The second step, And a divergence angle difference from the recording medium or the near field forming lens of each region in the undistorted polarized light. Instead of passing through the second separation synthesis portion that passes only the polarization in a specific direction according to the polarization direction of the light reflected from the recording medium, the non-distorted polarization reflected by the second separation synthesis portion is received, and a portion of the region is A first separation and synthesis portion configured to pass through and reflect and separate the remaining areas; And And a detector configured to generate a gap error signal (GES) corresponding to the polarized light passing through the first separation synthesized portion or the polarized light reflected from the first separated synthesis portion. The method of claim 6, And a lens configured to form different focal lengths of the respective areas by the divergence angle difference from the recording medium or the near field forming lens of the partial area and the remaining area. A lens for receiving undistorted polarized light reflected by the second separated synthesis portion without passing through the second separated synthesis portion passing only the polarization in a specific direction according to the polarization direction of the light reflected from the recording medium; And And a detector configured to generate a gap error signal (GES) and a recording / playback signal (RF) using the undistorted polarization received from the lens. The method of claim 8, And said lens is such that each region forms a different focal length due to a divergence angle difference from a recording medium or a near-field forming lens of each region in the undistorted polarized light. The method of claim 8, The detection unit, An optical pickup comprising a plurality of light receiving cells configured as one or a multi-division region, and generating the gap error signal GES and the recording / reproducing signal RF by using a sum of the amounts of light between the multi-division regions or the light receiving cells. . Instead of passing through the second separation synthesis portion that passes only the polarization in a specific direction according to the polarization direction of the light reflected from the recording medium, the non-distorted polarization reflected by the second separation synthesis portion is received, and a portion of the region is An optical pickup that passes through and reflects and separates the remaining area; And And a control unit for controlling the optical pickup to record data on the recording medium or to reproduce the recorded data.

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