KR20080111690A - Method for recording/reproducing on/from a recording medium and apparatus for the same - Google Patents

Abstract

A recording medium record/playback method and apparatus are provided to resolve instability of servo and improve the signal to noise ratio of record/playback signal. A recording medium record/playback method comprises a step of separating beam reflected or diffracted from a recording medium by using a beam splitter(S110), a step of receiving a part of one or more of the separated beams and generating a first signal(S120), a step of receiving the whole parts of one or more of the separated beams and generating a second signal(S130), and a step of detecting tilt or/and de-center of the recording medium by using the first and second signals(S140,S150).

Description

Recording medium recording / reproducing method and recording medium recording / reproducing apparatus {Method for recording / reproducing on / from a recording medium and Apparatus for the same}

1 is an embodiment of a recording medium recording / reproducing apparatus according to the present invention.

2 is an embodiment of an optical system according to the present invention.

3 is an embodiment of a lens unit according to the present invention.

4 is an embodiment of an optical system according to the present invention.

Figure 5 is an embodiment showing the shape of a beam received by the optical system according to the present invention.

6 is an embodiment of a recording / reproducing method according to the present invention.

7 is an embodiment of a recording / reproducing method according to the present invention.

The present invention relates to a recording medium recording / reproducing method and a recording medium recording / reproducing apparatus, and more particularly, to a method and method for determining and controlling the position of a recording apparatus for recording / reproducing a recording medium.

In general, a recording medium recording / reproducing apparatus is a device for recording data on a recording medium such as a compact disc (CD) or a digital versatile disc (DVD), or reproducing data recorded on a recording medium. In addition, advances in technology have led to the emergence of next-generation recording media with more capacity than CDs or DVDs. Examples of such next-generation recording media include BD (Blu-ray Disc), Near Field Recording (NFR), Hologram (Hologram) recording media, and the like. As described above, there is a demand for a recording medium recording / reproducing apparatus and a recording / reproducing method which are more precisely controlled as the recording medium becomes higher in capacity and density.

The present invention solves the above problems, and relates to a recording medium recording / reproducing method and a recording / reproducing apparatus for more precisely controlling the position between the recording medium and the recording apparatus.

In order to achieve the above object, the present invention includes the steps of separating the beam reflected or diffracted from the recording medium; Generating a first signal by receiving only the partial region of the separated at least one beam, and generating a second signal by receiving the entire region of the separated at least one beam; The present invention provides a recording medium recording / reproducing method, wherein the tilt and / or de-center of a recording medium is detected using the first signal and the second signal.

Another object of the present invention is to separate a signal reflected or diffracted from a recording medium, to generate a first signal using a partial region of the separated at least one beam, and to use the entire region of the separated at least one beam. Pick-up unit for generating a second signal; And a control unit for detecting tilt and decenter between the recording medium and the pickup unit using the first signal and the second signal.

Still another object of the present invention is to pass only a partial region of the beam reflected or diffracted from the recording medium; Receiving the passed beam using a multi-stage light receiving element; It is to provide a tilt detection method, characterized in that to obtain the degree of inclination between the recording medium and the pickup unit by using the received signal.

Still another object of the present invention is to inject a beam into a recording medium; Receiving a reflected or diffracted beam from the recording medium to generate a first signal including information about tilt, and to generate a second signal including information about tilt and decenter; the first signal and It provides a recording medium recording / reproducing method comprising the step of detecting and controlling the tilt and de-center from the second signal.

Another object of the present invention is to provide a slit for passing a portion of a beam reflected or diffracted from a recording medium; A first detector configured to detect a first signal passing through the slit and including information about the tilt; A second detector configured to detect a second signal including information about the tilt and the decenter without passing through the slit; It provides a recording medium recording / reproducing apparatus comprising a control unit for detecting the tilt and de-center between the recording medium and the pickup unit by using the first signal and the second signal.

Hereinafter, exemplary embodiments of a recording medium recording / reproducing method and a recording / reproducing apparatus according to the present invention will be described in detail with reference to the accompanying drawings.

In addition, the terms used in the present invention was selected as a general term widely used as possible, but in some cases, the terms arbitrarily selected by the applicant, and in this case, since the meaning is described in detail in the description of the invention, It is to be understood that the present invention is to be understood as the meaning of terms rather than names.

In this regard, in the present invention, "recording medium" means any medium on which data is recorded or is recordable, and encompasses all mediums regardless of a recording method such as a disc, a magnetic tape, and the like. Hereinafter, the present invention will be described by using a disk, in particular, a " close-up recording medium, " as an example for the convenience of description. However, the technical concept of the present invention is obviously applicable to other recording media.

1 shows an embodiment of a recording / reproducing apparatus according to the present invention. The recording and reproducing apparatus according to the present invention includes components such as the pickup unit 100, the signal generator 200, the controller 300, the servo driver 400, the decoder 500, the encoder 600, and the ATAPI 700. It includes. In addition, it may further include a component such as a host.

The pickup unit 100 irradiates light to the recording medium, and collects light reflected or diffracted from the recording medium to generate a signal. At this time, it is required to precisely control the position of the pickup section in order to record / reproduce the recording medium more accurately. In particular, when the position between the recording medium and the pickup section is not accurately controlled, it becomes difficult to read accurate information from the recording medium. There are various types of positional deviation between the recording medium and the recording apparatus. For example, when the gap, which is the vertical distance between the recording medium and the pickup unit, is not accurately aimed, the pickup unit is horizontally deviated from the track of the recording medium, or the pickup unit is inclined relative to the recording medium. have.

Of these, the case where the pickup section is horizontally deviated from the track of the recording medium may be referred to as a de-center for convenience. In addition, the case where the pickup part is inclined relative to the recording medium may be referred to as a tilt for convenience. Tilt may occur in the radial direction or the tangential direction with respect to the track direction of the recording medium, or may include both components.

The detailed configuration of the pickup unit 100 will be described in detail later with reference to FIGS. 2 to 3.

The signal generator 200 generates an RF signal, a gap error signal, a track error signal, and the like necessary for the control using the signal generated by the pickup unit 100.

The controller 300 receives a signal generated by the signal generator 200 and generates a control signal or a drive signal. In addition, the controller may receive a signal generated by the signal generator 200 and determine and / or control a relative positional relationship between the pickup unit 100 and the recording medium. In more detail, the above-described tilt or de-center may be determined and controlled.

In addition, the servo driver 400 includes a gap servo driver, a tracking servo driver, and a slad servo driver.

The encoder 500 converts an input signal into a signal of a specific format, for example, an MPEG2 transport stream, and provides it to the signal processor 200 under the control of the controller 300 to perform a function of recording a signal on a disk. Can be.

The decoder 600 may decode the signal read from the disc under the control of the controller 300, restore the desired information, and provide the same to the user.

A host such as a PC may be connected to the recording and reproducing apparatus. The host transmits a recording and reproducing command to the controller 300 through an interface, receives the reproduced data from the decoder 500, and transmits data to be recorded to the encoder 600. The controller 300 may control the decoder 500, the encoder 600, and the controller according to the recording / reproducing command of the host. Alternatively, a host may download data through a network such as the Internet and control a recording / reproducing of a recording medium. Alternatively, the controller of the recording / playback apparatus may serve as a host.

In this case, the interface may generally use a device such as Advanced Technology Attached Packet Interface (ATAPI) 700. The ATAPI 700 is an interface standard between the recording and reproducing apparatus and the host. The ATAPI 700 is a standard for transmitting the decoded data from the optical recording and reproducing apparatus to the host, and converts the decoded data into a packet-type protocol that is data that can be processed by the host. To transmit.

2 illustrates an embodiment of an optical system according to the present invention. The optical system shown in FIG. 2 may be an element included in the pickup unit 100. In addition, in FIG. 2, the operation sequence will be described in detail with reference to the flow of signals based on the traveling direction of the light emitted from the light source inside the optical system.

The optical system shown in FIG. 2 includes a light source 110, separation and synthesis units 120 and 130, a lens unit 140, a first light receiving unit 150, and a second light receiving unit 160. In addition, the optical system illustrated in FIG. 2 may further include a collimator lens (CL). The collimator lens serves to make the light emitted from the light source 110 into parallel light.

In the embodiment shown in FIG. 2, the light emitted from the light source 110 is incident on the first separation synthesis unit 120, partly reflected and partly passed through and incident on the second separation synthesis unit 130. The second separation synthesis unit 130 passes the vertically polarized light component and reflects the horizontally polarized light component from the linearly polarized light. In addition, the first separation unit may be a non-polarization beam splitter, and the second separation unit may serve as a polarization beam splitter. Obviously, the roles of the first separation synthesis unit 120 and the second separation synthesis unit 130 may be changed. A polarization conversion surface (not shown) may be further included on the path of the light passing through the second separation synthesis unit 130.

Light passing through the second separating synthesis unit 130 is incident to the lens unit 140. The light incident on the objective lens of the lens unit 140 passes through the near field forming lens to form a dissipated wave. Specifically, light incident on the near field forming lens at an angle equal to or greater than a critical angle is totally reflected at the surface of the lens and the surface of the recording medium 900. Light incident on the near field forming lens at an angle not exceeding the critical angle is reflected on the recording layer of the recording medium 900. The dissipation wave generated in this process reaches the recording layer of the recording medium and performs recording / reproducing.

The light reflected from the recording medium 900 is incident again to the second separation synthesis unit 130 through the lens unit 140. In this case, as described above, a polarization conversion surface (not shown) may be provided on the path incident to the second separation synthesis unit 130. The polarization converting surface converts the polarization directions of the light incident on the recording medium 900 and the reflected light. Therefore, when only the horizontal polarization component is passed by the second separation synthesis unit 130, the incident light is reflected by the recording medium 900 to have a vertical polarization component when it is incident on the second separation synthesis unit 130 again. . Therefore, the reflected light of the vertical polarization component is reflected by the second separation synthesis unit 130, and the reflected light is incident on the second light receiving unit 160.

That is, a part of the reflected light incident on the second separation synthesis unit 130 has a horizontal polarization component due to the distortion in the polarization direction, and passes through the second separation synthesis unit 130. The passed reflected light is incident to the first separation synthesis unit 120. The first separation synthesis unit 120 passes a part of the incident light and reflects the part. The light reflected by the first separating synthesis unit 120 is incident to the first light receiving unit 150.

In addition, the first light receiving unit 150 and the second light receiving unit 160 may receive a signal passing through the separation synthesis unit, and output an electrical signal corresponding to the amount of light. In addition, it will be apparent that the first light receiving unit 150 and the second light receiving unit 160 may be provided in various embodiments. Each of the first light receiving unit 150 or the second light receiving unit 160 may include at least one light receiving element. In addition, the light receiving element included in each of the light receiving units 150 and 160 may include a multi-division region. For example, the first light receiving unit may include two light receiving elements, and each light receiving element may be configured as a two division or a four division region. Obviously, the number of light-receiving elements constituting each light-receiving unit, the divided regions, etc. may be variously implemented.

In addition, the light receiving units 150 and 160 may use not only a light receiving element but also components that modify or specify the shape of a received beam. For example, the light receiver may further include a component such as a slit. In this case, the slit may serve to pass only a specific portion of the received beam.

On the other hand, in the near field recording and reproducing apparatus of the present invention, since the numerical aperture (Numeric Aperture, NA) of the lens unit 140 is larger than 1, distortion occurs in the polarization direction of light in the process of being irradiated and reflected through the lens unit 140.

In addition, although the present invention has been described using a near field recording medium as an example, it will be apparent that the optical components used in the present invention may be used in other recording media.

In addition, the lens unit is a portion for irradiating light to the recording medium and receiving light reflected or diffracted from the recording medium. Therefore, the position control between the recording medium and the lens unit 140 may be an important factor for stable recording / playback. An embodiment of the configuration of the lens unit 140 in the near field recording / reproducing apparatus is shown in FIG.

3 is an embodiment of a recording / playback apparatus according to the present invention. In particular, an embodiment of the lens unit 140 is illustrated. The lens unit 140 may include an objective lens 142 and a near field forming lens 144. The numerical aperture of the lens unit 140 is increased through the near field forming lens 144 to form an evanescent wave. As an example of the near field forming lens 144, a solid immersion lens (SIL) may be used. A hemispherical or ultra hemispherical lens may be used as the solid impregnation lens SIL. Alternatively, a near field forming mirror may be used without using the near field forming lens 144. When the near field forming mirror SIM is used, the objective lens may not be used.

The distance between the lens unit 140 and the recording medium 900 may be referred to as a gap. Obviously, the definition and name of the distance may vary depending on the type of recording medium and recording device. In addition, the optical system of the pickup unit including the lens unit 140 is located very close to the recording medium 900. For example, in the case of a near field optical system, the distance may be equal to or less than 1/4 (ie, λ / 4) of the wavelength. For example, when using a wavelength of about 405nm, the proximity distance may be less than 100nm.

In addition, the near field optical system includes the following features at a distance of? / 4 or less. When the lens unit 140 and the recording medium 900 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 140 maintains its properties and is used for recording and reproduction. Can be. However, when the distance between the lens unit 140 and the recording medium 900 is λ / 4 or more, the wavelength of the light loses the property of the dissipated wave. Therefore, in the recording / reproducing apparatus using the near field, the lens unit 140 is maintained so that the distance from the recording medium 900 does not exceed approximately [lambda] / 4. Is the limit of the near field.

4 is an embodiment of a recording medium recording / reproducing apparatus according to the present invention. More specifically, it is an embodiment of an optical system according to the present invention. The optical system according to the present invention includes a light source 110, a collimator lens CL, a first separation synthesis unit 120, a second separation synthesis unit 130, a quarter wave plate (QWP), and a beam. It may include a expander (Beam expander), the lens unit 140, the first light receiving unit 150, the second light receiving unit 160. In the embodiment of FIG. 1, the above-described components will be omitted and descriptions will be made based on the components not shown in FIG. 1.

In the present invention, a beam expander may serve to expand a beam incident from a light source. In addition, QWP serves to change the polarization direction. For example, vertical polarization can be converted to horizontal polarization or horizontal polarization to vertical polarization. Right Angle Prism is used to change the light path. In addition, a right angle mirror may be used instead of the right prism to change the optical path.

In addition, the first separation combining unit 120 may include at least one beam splitter. For example, in the embodiment of FIG. 4, two beam splitters 122 and 124 are included. The dual first beam splitter 122 may play a role of the first separation synthesis unit described above with reference to FIG. 2. In addition, the second beam splitter 124 may be used to bisect the beam incident by the first beam splitter 122 of the recording medium.

In addition, the light receiving units 150 and 160 of the present invention may include sensor lenses SL 152, 153, and 162. The sensor lens SL collects light received by the light receiving element. Here, the focal length of the sensor lens is an element that can vary depending on the configuration of the recording device. Depending on the focal length of the sensor lens, the arrangement distance of the light receiving elements 156.158 and 166 may also vary.

In addition, the light receiver of the present invention may include a slit 154. The slit 154 may separate the beam of a specific region from the incident beam. For example, in the recording medium recording apparatus shown in FIG. 4, the beams passing through the first beam separator 122 and the second beam separator 124 of the first separation unit are incident on the sensor lenses 152 and 153, respectively. At this time, the beam passing through the slit passes only the beam of a specific region and is received by the light receiving element 156. For convenience, a beam passing through the slit among the beams passing through the first separation synthesis unit may be referred to as a "first signal", and a beam not passing through the slit may be referred to as a "second signal".

Shapes and characteristics of the first signal and the second signal will be described in detail later with reference to FIG. 5.

The direction of the slit 154 may vary depending on the component to be corrected in the recording apparatus. As an example, the longitudinal direction of the slit 154 may be arranged in a direction parallel to the radial direction of the recording medium track. In this case, the tilt in the radial direction between the recording medium and the pickup portion can be detected. As another example, the length direction of the slit 154 may be arranged in a direction parallel to the tangential direction of the recording medium track. In this case, the tangential tilt between the recording medium and the pickup portion can be detected.

In addition, the shape of the slit may be used to detect a beam of a specific area among the received beams. For example, the groove of the slit can be centered. In this case, the received beam may be divided (left, middle, and right) in a direction parallel to the longitudinal direction of the slit to receive the beam in the center thereof.

The light receiving elements 156, 158, and 166 are used to receive the first signal passing through the slit after passing through the sensor lens, or the second signal not passing through the slit. The arrangement of the light receiving element and the characteristics of the divided region can be used to control the position of the pickup portion. For example, of the light receiving elements shown in FIG. 4, the light receiving element 156 that receives the beam passing through the slit may be a light receiving element composed of two divided regions. In this case, the direction of the divided region of the light receiving element may be perpendicular to the direction of the slit as shown in FIG. 4. At this time, the tilt of the pickup unit 100 can be detected using the difference between the upper and lower regions.

Alternatively, the arrangement of the slit 154 and the light receiving element 156 among the components shown in FIG. 4 may be rotated by 90 °. In this case, as described above, the tilt in the tangential direction may be detected.

Also, a light receiving element having a quadrant region may be used as the light receiving element 154 that receives the first signal. Even in the case where a light-receiving element in a four-division region is used, it is obvious that the difference between the symmetrical regions of the upper, lower, and left and right regions can be obtained according to the direction in which the slits are arranged.

In addition, the light receiving element 158 that receives the second signal may also have a two or four division area. While the tilt between the recording medium and the pickup unit can be detected using the light receiving element 156 that receives the first signal, the signal received by the light receiving element 158 that receives the second signal includes a tilt and a decenter. -center) can be included. In this case, the tilt may be detected using the first signal, and only the component of the center may be detected from the second signal using the detected tilt.

It may be used to detect a track error signal, an RF signal, etc. using the beam passing through the second separation synthesis unit 130. In addition, it will be apparent that the number of divided regions of the light receiving element used in receiving the beam passing through the second separating synthesis unit can be set variously according to the characteristics and the purpose of the recording / reproducing apparatus. As one example, a light receiving element having a two or four division region may be used.

Alternatively, it is apparent that a slit and / or beam separator may be used in the second separation composition depending on the type of recording medium and the recording apparatus.

Figure 5 shows an example of the form of the signal received in the recording medium recording and reproducing apparatus according to the present invention. More specifically, the forms of the first signal and the second signal of the present invention are shown. I, II, III, and IV show the first and second signals received under different conditions. The first signal, which is a beam passing through the slit, is a signal received by the light receiving element 156 shown on the left side, and the second signal, which is a beam not passing through the slit, is a signal received by the light receiving element 158 shown on the right side. . In addition, in the present embodiment, the slit divides the received beam into three parts and transmits only the center part.

I represents the signal received when the pickup is in the normal position. At this time, the upper and lower regions of the first signal are symmetrical, and their brightness is also uniform. It can be seen that the second signal is also uniform in brightness and symmetrical in the upper and lower regions. At this time, there is no difference between the upper and lower regions of the received first signal and the second signal.

II shows the first signal and the second signal received by the light receiving element when the pickup section is tilted with respect to the recording medium. In the case of II, there is no de-center between the recording medium and the pickup, but only tilt. At this time, the centers of the received first and second signals are well-fitted to the receiver, but the brightness is not uniform. In the case of the signal shown in II, it can be seen that the upper region is brighter than the lower region. For example, the magnitude of the signal received in the upper region is G1, the magnitude of the signal received in the lower region is G2, and the difference between the upper region and the lower region is α. It can be seen that the following equation holds. In other words,

G1-G2 = α (II).

In this case, the difference between the upper and lower regions of the second signal also exists. When the signal received in the upper region of the second signal is H1 and the signal received in the lower region is H2, the brightness difference may be β. In other words,

H1-H2 = β (II).

III shows an embodiment in which the pickup section is tilted with respect to the recording medium and a de-center between the recording medium and the pickup section also occurs. In other words, the center of the pick-up section is tilted while being horizontally moved in one direction with respect to the track to be reproduced. As compared with the embodiment shown in II, it can be seen that the difference between the upper and lower regions of the first signal transmitted only through the center portion using the slit is constant. This is because only a certain area is used using the slit. In other words,

G1-G2 = α (III).

On the other hand, the difference of the second signal is larger than the difference shown in II. This is because the pickup section has moved relatively upward. In other words,

H1-H2> β (III).

IV shows a case where the recording medium and the pickup section are decentered and tilted. However, the pickup part is de-centered in the opposite direction to the embodiment shown in III. In the case of the first signal, even if there is a de-center, the difference between the upper and lower regions is constant. In other words,

G1-G2 = α (IV).

In addition, since the pick-up portion has moved downward, in the case of the second signal, the difference between the upper and lower regions is as follows.

H1-H2 <β (Ⅳ)

That is, it can be seen that the difference between the upper and lower regions of the first signal is only affected by the tilt of the pickup unit. This is because only the beam of a predetermined area is received using the slit as described above. Accordingly, the tilt degree of the pickup unit 100 may be detected using the difference between the upper and lower regions of the first signal. In addition, it can be seen that the tilt detected using the difference between the upper and lower regions of the first signal is not affected by the de-center.

In addition, it can be seen that the difference between the upper and lower regions of the second signal reflects both the tilt component and the de-center component. Accordingly, if the tilt is detected using the first signal and then applied to the second signal, the de-center may also be detected. This may be done by correcting the decenter amount detected in the step of generating the control signal. Alternatively, the difference between the upper and lower regions of the first signal may be multiplied by a constant coefficient to add or subtract the difference between the second signal.

In addition, the sum of the second signals may be used to generate a gap error signal.

6 is an embodiment of a recording medium recording / reproducing method according to the present invention. More specifically, the method for detecting and controlling the tilt of the pickup unit is an embodiment.

First, a first signal is obtained (s10). Here, the first signal indicates that the beam reflected or diffracted from the recording medium passes through the slit as described above. As shown in FIG. 5, the beam passing through the slit has a shape in which only a partial region is transmitted. For example, as illustrated in FIG. 4 or FIG. 5, the first signal may be a signal that passes only the center region of the incident beam. Further, as described above, the first signal contains the tilt component of the recording medium.

The difference between the upper and lower regions is obtained from the received first signal (S20). In the present invention, the signals received in the upper and lower regions are named G1 and G2 for convenience. As described above, G1-G2, which is the difference between the upper and lower regions, is affected by the degree of tilt irrespective of the decenter between the recording medium and the pickup unit 100, and thus the tilting between the recording medium and the pickup unit is performed using G1-G2. The degree can be detected (s30). In addition, after detecting the tilt degree, it may be used to control the pickup unit again (S40). At this time, it is possible to confirm whether the tilt of the recording medium and the pickup unit is properly controlled by using the values of G1-G2.

7 is an embodiment of a recording medium recording / reproducing method according to the present invention. More specifically, FIG. 7 illustrates a method of separating tilt and de-center of the recording apparatus according to the present invention.

First, the beam reflected or diffracted from the recording medium is separated (S110). In this case, the beam to be separated may be a beam having the same polarization direction. In this case, at least one of the separated beams passes through the slit 154 to obtain a first signal (S120). The slit 154 may be parallel to the radial direction of the record carrier track and / or the tangential direction of the record carrier track. In addition, at least one of the separated beams is received without passing through the slit to obtain the second signal s130.

The tilt of the recording medium is detected using the received first signal (S140). This may detect whether or not the tilt in each direction using the difference between the upper and lower regions or the left and right regions of the received first signal. In addition, the direction of the detected tilt may vary depending on the direction of the slit.

De-center and tilt of the recording medium may be detected using the received second signal (S150). However, since the components for the de-center and the components for the tilt are mixed, the second signal may need to be separated.

The tilt degree is detected using the first signal and a control signal is generated to control the position of the pickup unit (S160).

In addition, the de-center may be detected by removing a component related to the tilt from the second signal in which the de-center and the tilt are mixed (S170). This may be done by using a tilt control signal or by using a first signal.

The de-center control signal is generated using the detected de-center degree, and the de-center is controlled (S180).

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the technical spirit of the present invention.

Therefore, the technical scope of the present invention should not be limited to the contents described in the embodiments, but should be defined by the claims.

The recording medium recording / reproducing method and the recording / reproducing apparatus according to the present invention have the following effects. The recording / reproducing method and the recording / reproducing apparatus according to the present invention are for precisely controlling the position of the recording / reproducing apparatus with respect to the recording medium, to solve the servo instability, and to reduce the signal to noise ratio of the recording / reproducing signal. Can improve.

Claims (39)

Separating the beam reflected or diffracted from the record carrier; Generating a first signal by receiving only the partial region of the separated at least one beam, and generating a second signal by receiving the entire region of the separated at least one beam; And a tilt and / or de-center of the recording medium is detected using the first signal and the second signal. The method of claim 1, And dividing the beam by using a beam splitter. The method of claim 1, The generating of the first signal may include generating the separated beam through a slit. The method of claim 3, wherein And the direction of the slit is parallel to the beam in the radial direction of the track of the record carrier. The method of claim 3, wherein And the direction of the slit is parallel to the beam in the tangential direction of the record carrier track. The method of claim 1, Generating the second signal does not pass the split beam through a slit. The method of claim 1, And a tilt is detected by using the first signal. The method of claim 7, wherein The detecting of the tilt is performed by obtaining a light quantity difference between symmetrical regions of the light receiving element including a plurality of divided regions. The method of claim 8, And the light receiving element is a two-part or four-part light receiving element. The method of claim 1, And detecting the tilt and decenter comprises detecting the tilt and the decenter using a second signal. The method of claim 1, The detecting of the decenter comprises excluding a tilt component detected using the first signal from the second signal. Separating signals reflected or diffracted from a recording medium to generate a first signal using a partial region of the separated at least one beam, and generate a second signal using the entire region of the separated at least one beam. Pick-up unit; And a control unit for detecting a tilt and a decenter between the recording medium and the pickup unit using the first signal and the second signal. The method of claim 12, And a beam splitter for separating the reflected or diffracted signal. The method of claim 12, And the first signal is generated by passing the separated beam through a slit. The method of claim 14, And the direction of the slit is parallel to the beam in the radial direction of the track of the record carrier. The method of claim 14, And the direction of the slit is parallel to the beam in the tangential direction of the record carrier track. The method of claim 14, And generating the first signal by receiving the beam passing through the slit by using a multi-segment light receiving element. The method of claim 12, And the second signal is generated without the separated beam passing through a slit. The method of claim 18, And generating the second signal comprises receiving a beam not passing through the slit by using a multi-stage light receiving element. The method of claim 12, And detecting the tilt comprises receiving the first signal and obtaining a difference between divided regions. The method of claim 20, And obtaining a difference between the divided areas is to obtain a difference between symmetrical areas. The method of claim 12, And detecting the decenter comprises correcting a tilt amount detected by using the first signal in the second signal. Passing only a partial region of the beam reflected or diffracted from the recording medium; Receiving the passed beam using a multi-stage light receiving element; And a tilt degree between the recording medium and the pickup unit is obtained using the received signal. The method of claim 23, Passing only a partial region of the beam, the tilt detection method characterized in that the beam passes through the slit. The method of claim 24, And the slit may be located in parallel with a radial direction of a track of the recording medium. The method of claim 24, And the slit may be located in parallel with a tangential direction of a track of the recording medium. The method of claim 23, Using the received signal, the tilt detection method, characterized in that to obtain the light quantity difference of the symmetric region of the signal received by the multi-stage light receiving element. The method of claim 27, And the light quantity difference is proportional to the inclination between the recording medium and the pickup unit. Injecting a beam into the recording medium; Receiving the reflected or diffracted beam from the recording medium, generating a first signal including information about the tilt, and generating a second signal including information about the tilt and decenter; And detecting and controlling a tilt and a decenter from the first signal and the second signal. The method of claim 29, And generating the first signal by receiving a beam reflected or diffracted from the recording medium through a slit. The method of claim 29, And generating the second signal receives a beam reflected or diffracted from the recording medium without passing through the slit. The method of claim 29, Detecting the tilt from the first signal, the tilt is detected by obtaining the difference of the symmetrical region of the first signal. The method of claim 32, And the symmetrical area obtains a difference between the symmetrical areas in a vertical direction with respect to the longitudinal direction of the slit. The method of claim 29, And detecting the decenter comprises excluding a tilt component detected from the first signal from the second signal. A slit for passing a portion of the beam reflected or diffracted from the record carrier; A first detector configured to detect a first signal passing through the slit and including information about the tilt; A second detector configured to detect a second signal including information about the tilt and the decenter without passing through the slit; And a control unit for detecting a tilt and a decenter between the recording medium and the pickup unit using the first signal and the second signal. 36. The method of claim 35 wherein And the direction of the slit is parallel to the beam in the radial direction of the track of the record carrier. 36. The method of claim 35 wherein And the direction of the slit is parallel to the beam in the tangential direction of the record carrier track. 36. The method of claim 35 wherein The detecting of the tilt is to obtain a difference between the divided regions of the first signal received by the first detection unit. 36. The method of claim 35 wherein And detecting the decenter comprises excluding a tilt component detected from the first signal from the second signal.

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