KR20050060274A - Apparatus and method of optical reading and writing - Google Patents

Abstract

The present invention relates to an apparatus and a method for controlling a servo control unit by using a reflected light by setting a reflecting unit on a predetermined portion of an optical recording medium, and varying a position to be collected on the optical recording medium by adding depth adjusting means. .

The present invention includes a first reflecting means for reflecting the input light by adjusting the amount of light output from the light output means; Second reflecting means for reflecting light input through the first reflecting means; an objective lens for condensing the incident light reflected by the first and second reflecting means onto an optical recording medium; And depth control means for passing the light passing through the first reflecting means to adjust the depth of the light to be focused through the objective lens.

Thus, according to the present invention, focus and tracking on a homogeneous volume storage medium

You can use the servo to record and play back to the desired location.

Description

Apparatus and method of optical reading and writing

The present invention is to accurately set the area of recording and reproducing data in a high density optical recording medium system with a simple structure, in particular to set the reflector to a certain portion of the optical recording medium to control the servo control unit using the reflected light, The present invention relates to an apparatus and a method for varying a position where a light is collected on an optical recording medium by adding depth adjusting means.

Today, the storage medium is changing from tape to disk due to the digitalization and large capacity of data, and the disk storage capacity is increased by increasing the recording density for storing data on the disk. Doing.

Therefore, in high density optical discs, the distance between signal tracks, that is, the signal track pitch, is reduced in order to increase the recording density.

In this case, the optical disk may be warped during the injection and curing of the resin in the manufacturing process, and this may cause an eccentricity even when the center hole is drilled.

In addition, even if the track of the disc is accurately recorded in a spiral shape at a pitch of a predetermined standard, the center hole is deviated, thereby causing eccentricity and disc tilt (tilt).

Thus, the disk rotates with eccentricity, so it is difficult for the central axis of the motor and the center of these tracks to completely coincide.

Therefore, since it is difficult to read exactly the signal of the desired track accurately, the CD and DVD system sets the standard for this misalignment amount, and the tracking servo is performed so that the light beam can always follow the desired track even if such eccentricity occurs.

That is, the tracking servo generates an electric signal corresponding to the beam trace state and based on the signal, moves the objective lens and the optical pickup main body in the radial direction to correct the position of the beam to accurately track the track.

On the other hand, when the beam deviates from the track, not only the eccentricity of the disc described above but also the case where the disc is inclined. This can occur due to mechanical problems such as errors when mounting the disk to the spindle motor. In other words, the focusing and tracking do not exactly match vertically. In this way, the disk is tilted.

Typically, an optical disc recorder should keep the optical disc level during recording and playback, but due to mechanical errors and assembly tolerances of the optical pickup and spindle motor, the optical disc has a radial (secondary radial) direction and information track. It is tilted in the direction of tangent (hereinafter called tangential).

FIG. 1 is a block diagram of an optical disc for tilt control according to the present invention, in which information is recorded and reproduced on an optical disc 101, which is an optical recording medium, and an optical detector 102a appears by converting light beams reflected from the optical disc into electrical signals. An optical pickup unit 102 and a tilt error detector 106 that detects a tilt error signal using a push pull signal in a tangential direction, and generates a servo error signal from an electrical signal output from the optical pickup unit. A servo error generator 103, a tracking error detector 104 for detecting a tracking error signal generated by the servo error generator, and a focus error detector 105 for detecting a focus error signal generated by the servo error generator. ), And a tangential push pull error detecting unit (ie, a tilt error detecting unit 106) for detecting a tangential push pull error signal generated by the servo error generating unit. have.

A servo controller 108 for generating and outputting a control signal to control the servo by the signal detected by the error detector, and a tilt for controlling the servo by controlling the optical pickup unit according to a drive signal output from the servo controller The control unit 109 is included.

In the optical recording / reproducing apparatus operated as described above, as the optical storage technology advances, the wavelength reduction of the LD (laser diode) and the high NA (normal numerical aperture) process of the objective lens are performed, resulting in high density of recording information. BD (Blue Disk) has come, but more methods have been proposed without any obvious representative technology.

One possible possibility is volume recording.

The volumetric storage media volume storage method is one of the alternatives for overcoming the conventional two-dimensional disc storage technology as the storage technology approaches the limit. Field.

Representative technologies include 1) Holographic type page oriented recording, 2) Two-photon bit oriented recording, and 3) Multilayer.

1) Holography: Records the interference fringes between the reference beam and the information beam in a photorefractive medium that is photoreactive, and later reproduces them with the reference beam to record the 2D page information by using a lens, which is called multiplexing. Therefore, it is possible to superimpose recording while giving a difference in angle, wavelength, etc. in one space.

2) Two-photon: The specific medium absorbs two photons of a specific wavelength, and the absorbed part has a change in refractive index. The mark is made by using light of another wavelength. Since the recording / reproducing is not by reflection but by fluorescence, it can be used up to depth in a homogeneous 3D medium without the need for a reflective surface.

Information is a method of recording bit information instead of page information (although there is a page recording method as a variant). The characteristic is that the mark occurs only in a limited area because the limit light intensity at which the two-photon phenomenon occurs is very large.

3) Multilayer: A technology that generally extends the dual layer method from the conventional DVD technology. Although multiple reflective layers are made, there is a limitation in recording quality (jitter) because loss occurs in each reflective layer.

As a simple extension of the prior art, a high degree of completeness is required but a solution to the spherical aberration compensation problem and the recording / reproducing light loss problem is required.

However, in the case of 1) and 2) using a homogeneous 3D medium, the tracking and focusing servo for identifying and tracking each recording position becomes a very difficult problem.

In particular, the method of forming a homogeneous volume without uniform reflection layers on the entire media, such as holography or two-photon technology, seems to be powerful. One of the major problems in this method is that focus and tracking servos can be applied during recording and playback. There is no reflective layer.

In the normal pickup, the focusing layer, the recording layer and the reflecting layer, has a different refractive index than the base layer, and the servo is driven by the reflected light. In the case of the tracking servo, the grounding layer or the pre-planted pit is used. This is not possible in

On the other hand, the research-level technology that has not been commercialized yet uses a device that can move the position precisely, such as a stepping motor, but considering the size and density of the storage mark, there is a high possibility of error and almost no commercialization is possible. impossible.

       Therefore, in order to overcome the problems of inaccuracy and non-economics of the precision positioning mechanism (stepping motor, etc.) used in the conventional volume storage method, which is the above problem, the reference reflective structure surface is formed on the bottom of the volume storage medium. The objective is to divide the output light of the light source so that the servo servo light and the recording / reproducing main light use the same objective lens and actuator so that the focus and tracking servo can be placed at a desired position to enable stable operation. .

An optical recording / reproducing apparatus according to the present invention for achieving the above object includes a first means for outputting and condensing light, and adjusting the amount of light output from the optical output means to reflect the input light. Reflecting means; Second reflecting means for reflecting light input through said first reflecting means; An objective lens for condensing the incident light reflected by the first and second reflecting means onto an optical recording medium; And depth control means for passing the light passing through the first reflecting means to adjust the depth of the light to be focused through the objective lens.

For example, the optical recording medium is a volume storage medium, and the reference reflective structure surface can be formed at a certain point on the bottom, in the middle or on the top.

For example, the servo of focusing and tracking of the optical recording medium is controlled by using the light reflected through the reference reflecting structure surface.

For example, the objective lens and the actuator use the same recording / reproducing main light passing through the first reflecting means and servo light output from the second reflecting means.

For example, the depth control means is formed between the first reflecting means and the objective lens.

For example, when the position of the depth control means is moved in the objective lens direction, the focusing depth of the main beam passing through the first reflecting means is formed shallow in the optical recording medium.

For example, when the position of the depth control means is moved in the opposite direction of the objective lens, the focusing depth of the main beam passing through the first reflecting means is formed deep in the optical recording medium.

In addition, the optical recording / reproducing method according to the present invention comprises the steps of forming a reflective surface on the optical recording medium; Dividing the light output from the light source and outputting it to two or more optical paths through polarizing means; The second optical path is incident on the optical recording medium through the objective lens and reflected from the reference plane; Controlling the servo driver by using the reflected light to perform focus and tracking; And setting the area to be recorded / reproduced by being condensed through the objective lens via the depth adjusting lens.

For example, the depth condensed on the optical recording medium is adjusted by moving the depth adjusting lens.

For example, recording or reproducing of data is performed in the adjusted area.

Other objects and features of the present invention will become apparent from the detailed description of the embodiments with reference to the accompanying drawings.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

      Fig. 2 is a block diagram showing servo control of the optical pickup apparatus and the surroundings for performing optical recording and reproduction.

As shown in the figure, a laser diode (LD) 201 for generating a laser light source and a collimator lens (CL) 202 for converting a laser light source generated from the laser diode 201 into parallel light. ) And a servo beam and a main beam reflected by a first polarization beam splitter (PBS1) to the parallel light incident through the collimator lens 202. The half wave plate (HWP) 203 for adjusting the amount of light so that the amount of light becomes a constant ratio, and the servo beam polarized in the PBS1 204 to form the second optical path are the second polarization beam splitter 205. And incident / reflected from the optical storage medium (Volumetric media) 211 through the BS (Beam Spot) 208, QWP (Quarter Wave Plate), objective lens (OL) & Actuator (210) Servo control circuit that senses Servo PD 212 through BS and PBS2 and controls focusing and tracking 213).

Meanwhile, the main beam passing through the first PBS1 204 to form the first optical path is the core of the present invention with the mirror 206 and can move left and right for focusing a recording / reproducing area (position) on the volume storage medium. Optical storage media volume storage via BS, QWP, OL & Actuator via Depth Control Lens (207), QWP (Quarter Wave Plate), Objective Lens (OL) & Actuator (210) It is recorded / reproduced / reflected in the volumetric media 211 and polarized in the first PBS1 via a BS, depth control lens, and mirror, and detected by the photodetector (PD) 214.

The operation between the configurations in FIG. 2 is described further.

First, the present invention divides the output light from the light source of the pickup into two, one is used as a main beam for recording / reproducing, and the other is used as a servo beam for applying a servo to a reference plane. As shown in FIG. 3, in a homogeneous volume storage medium, a ground / groove structure or pre-pit to be used for tracking and a reflective layer to be referred to at the bottom is made, and a focusing point of the main beam is a depth adjusting lens 207. The recording / reproducing area (position) is made variable through.

In the above, the HWP 203 is for adjusting the ratio divided into two lights, PBS1, PBS2 and QWP are for maximizing the light efficiency entering each PD, the main light is used to adjust the depth direction focus position using the depth adjustment lens The servo light is focused on the reference plane at the bottom of the volume storage medium.

 The servo light and the main light are combined in a BS and pass through a common objective lens and an actuator. When the servo light is adjusted along a reference plane, the main light is adjusted together.

 Servo light is received by the servo PD and drives the actuator by a servo circuit, where the servo PD has a plane splitting sphere corresponding to a focus and tracking servo method used in a general pickup.

 If the depth adjustment lens is in one position, the relative depth of the main light and the servo light is kept constant so that both lights follow the land / groove or pre-pit at the bottom of the volume storage medium. By changing the adjustable lens at regular intervals, you can record / play back to the desired depth and desired track position.

 3 is a view showing a shape in which a reflective surface is formed on the bottom surface of the volume storage medium.

As shown in the drawing, the land / groove 301a is formed on the underside of the volume storage medium to perform reflection of the servo beam, and as the depth of recording / reproducing varies, the main beam is operated based on the operation of the depth adjusting lens 207. The focusing position of is changed.

In the above, when the position of the depth control means is moved in the objective lens direction, the focusing depth of the main beam passing through the first reflecting means formed in the optical recording medium becomes shallow, and the position of the depth control means in the opposite direction of the objective lens. In the case of movement, the focusing depth of the main beam passing through the first reflecting means formed on the optical recording medium is deepened.

In addition, the position (area) movement of the depth adjusting lens 207 is operated by the control of the microcomputer. For example, when recording, the recording depth of the main beam is adjusted by controlling the depth adjusting lens in the microcomputer when recording is performed in a part other than a predetermined one.

2 and 3 described above will be described.

The method of the present invention is divided into the main light corresponding to the recording / reproduction light in the normal pickup and the servo light for applying the servo to the reference plane, the servo light is reflected information of the reference plane made on the bottom of the volume storage medium and land / groove, pre It has focus and tracking information through information such as -pit and receives servo with PD for servo.

The main light is always kept at a constant distance from the servo light by using the same actuator and objective lens as the servo light. The optical path of the main light has a depth-adjustable lens to adjust the depth at which recording / reproducing on the volume storage medium and relative distance to the servo light

Retaining results in both focus and tracking servo effects.

As described above, the overall optical path of the pickup (FIG. 2) to which the focus and tracking servo method of the volume storage medium proposed by the present invention is applied is as follows.

Light from the LD passes through the collimation lens and passes through the HWP and PBS1 to split into main and servo light. The rotation of the HWP controls the ratio of the main and servo light.

Servo light passes through PBS2, BS, passes through QWP and is condensed by an objective lens and reflected off the reference plane at the bottom of the volume storage medium.

The light with servo information is passed back through the objective lens and the QWP to the servo PD through BS and PBS2, and the actuator is driven through the servo control circuit to maintain the focus and tracking servo.

On the other hand, after splitting at PBS1, the main light is focused through the depth-adjusting lens and through the BS to the desired recording / reproducing position past the QWP and the objective lens.

For example, in reproduction, the reflected light passes through the objective lens and the QWP, and then the BS, PBS1

It is received by the PD. At this time, the depth can be adjusted by using a depth adjusting lens, and this depth can have an effect of indirectly servoing because it maintains a constant distance from the reference plane followed by the servo light.

4 is a schematic flowchart operated for the optical recording / reproducing of the present invention.

The servo reference reflecting surface is formed on the optical recording medium (301 in FIG. 3) at the bottom, in the middle or above. (S 400).

       The light output from the light source LD is divided by the HWP and output to two or more optical paths of the servo beam and the main beam through the polarizing means PBS1. (S 401).

Servo is controlled by the second light, which is the servo beam, and the recording / reproducing area is set / changed by the depth adjusting lens. (S 302).

5 is a flowchart in which the position of the optical recording / reproducing of the present invention is changed and operated in the volume storage medium.

On the optical recording medium (301 in FIG. 3), the reflective reflection surface is formed on the bottom, in the middle, or on the top. (S 500).

The light output from the LD, which is a light source, is split in the HWP and output to two or more optical paths of the servo beam as the second light and the main (main) beam as the first light through the polarizing means PBS1. (S 501).

The second optical path, the servo beam, is incident on the optical recording medium through the objective lens and reflected at the reference surface formed on the bottom, middle, or top. (S 502).

The servo driver is controlled by using the reflected light to perform focus and tracking. (S 503).

On the other hand, the first optical path is set to the area to be recorded / reproduced by adjusting the depth focused on the optical recording medium by the positional movement of the depth adjustment lens. (S 504, S 505)

As described above, in the present invention, the reflector is set on the lower surface of the optical recording medium to control the servo control unit by using the reflected light, and the position where the main beam is focused on the optical recording medium is added by adding depth adjusting means. It relates to a device and a method that can be.

Although the preferred embodiment of the present invention has been described above, the present invention may use various changes, modifications, and equivalents. It is clear that the present invention can be applied in the same manner by appropriately modifying the above embodiments.

For example, the depth control method of the present invention can be equally applied to various types of volume storage media such as block type as well as disc type volume storage media.

 In addition, the reference surface, which is a reflective surface, may be formed on the intermediate layer or the upper surface by adjusting the reflectance as well as the bottom surface as in the storage medium of FIG. 3.

In addition, the method of the present invention has a much more accurate position value than the mechanically precise movement method and will be more commercialized.

Therefore, the above description is not limited to the scope of the present invention by the limitation of the claims.

  As described above, according to the optical recording / reproducing apparatus and method by depth control according to the present invention, recording is performed by using the same objective lens and actuator as the main light using the light dedicated to the servo by making a reference plane in the volume storage medium. Focus and track on homogeneous volume storage media that do not have a reference structure to servo to layers

You can use the servo to record and play back to the desired location.

 In addition, it is possible to configure a simple, precise and economical information storage device than the mechanical positioning method used conventionally.

It will also contribute to the commercialization of devices applying volume storage technology, which is expected to become the mainstream of optical recording technology in the future.

1 is a block diagram of an optical disk for tilt control of the present invention

Fig. 2 is a block diagram showing servo control around the optical pickup apparatus and performing optical recording and reproducing.

3 is a view showing a shape in which a reflective surface is formed on the bottom of the volume storage medium;

4 is a schematic flowchart operated for optical recording / reproducing of the present invention.

5 is a flowchart in which the position of the optical recording / reproducing of the present invention is changed and operated in the volume storage medium.

Claims (12)

An optical recording / reproducing apparatus comprising means for outputting and condensing light, First reflecting means for reflecting the input light by adjusting the amount of light output from the light output means; Second reflecting means for reflecting light input through said first reflecting means; An objective lens for condensing the incident light reflected by the first and second reflecting means onto an optical recording medium; And And depth control means through which the light passing through the first reflecting means passes to adjust the depth of the light to be focused through the objective lens. The optical recording / reproducing apparatus according to claim 1, wherein the optical recording medium is a volume storage medium, and the reference reflective structure surface can be formed at a certain point on the bottom, in the middle or on the top. The optical recording / reproducing apparatus according to claim 2, wherein the servo of focusing and tracking of the optical recording medium is controlled by using light reflected through the reference reflective structure surface. The optical recording / reproducing apparatus according to claim 2, wherein servo is applied to a mark recorded at an arbitrary position of the volume storage medium. The optical recording / reproducing apparatus according to claim 1, wherein the recording / reproducing main light passing through the first reflecting means and the servo light output from the second reflecting means use the same objective lens and actuator. The optical recording / reproducing apparatus according to claim 1, wherein the depth control means is formed between the first reflecting means and the objective lens. 7. The optical recording / reproducing apparatus according to claim 6, wherein the focusing depth of the main beam passing through the first reflecting means is shallow in the optical recording medium when the position of the depth control means is moved in the objective lens direction. The optical recording / reproducing apparatus according to claim 6, wherein the focusing depth of the main beam passing through the first reflecting means is formed deep in the optical recording medium when the position of the depth control means is moved in the opposite direction of the objective lens. . Forming a reflective surface on the optical recording medium;        Dividing the light output from the light source and outputting it to two or more optical paths through polarizing means; And And controlling the servo with the output second light, and setting / changing a recording / reproducing area through the depth adjusting lens with the first light. Forming a reflective surface on the optical recording medium; Dividing the light output from the light source and outputting it to two or more optical paths through polarizing means; The second optical path is incident on the optical recording medium through the objective lens and reflected from the reference plane; Controlling the servo driver by using the reflected light to perform focus and tracking; And And setting the area to be recorded / reproduced by being condensed through the objective lens via the depth adjusting lens. The optical recording / reproducing method according to claim 10, wherein the depth condensed on the optical recording medium is adjusted by moving the depth adjusting lens. 12. The optical recording / reproducing method according to claim 11, wherein data is recorded or reproduced in the adjusted area.