KR100692618B1 - A discriminating method of bd disk - Google Patents

Abstract

A discrimination method of a BD(Blu-ray Disk) is provided to be capable of discriminating a type of a BD with a focus error signal obtained by more largely setting an amplification ratio than before if the mounted BD is a low-reflectivity BD, thus even the BD of low reflectivity is accurately discriminated. A focus error signal and a photo detector sum signal are amplified in the first amplification ratio while a laser beam is emitted to a BD, in order to detect an S-curve of the focus error signal and reflectivity of the BD(50-54). If two S-curves exist, it is decided that the BD is a BD ROM(Read Only Memory) dual-layer disk, and if one S-curve exists while the reflectivity is at more than a reference level, it is decided that the BD is a BD ROM single-layer disk(56-70,58-72). If the reflectivity is smaller than the reference level, the focus error signal and the photo detector sum signal are amplified in the second amplification ratio larger than the first amplification ratio, in order to detect an S-curve of the focus error signal(60,62). If two S-curves are detected, it is decided that the BD is a BD R/RW(Recordable/ReWritable) dual-layer disk, and if one S-curve is detected, it is decided that the BD is a BD R/RW single-layer disk(64-68).

Description

A discriminating method of BD disk

1 is a block diagram showing an optical recording and reproducing apparatus to which a disc disc discrimination method according to an embodiment of the present invention is applied.

Fig. 2 is a chart showing the reflectances of the BD ROM, BD R and BD RW discs.

3 is a flowchart illustrating a method of discriminating a BD disc according to an embodiment of the present invention.

* Description of the symbols for the main functions of the drawings *

10: Pickup department 11: Laser diode

12: Photodetector 13: Actuator

14: objective lens 20: RF processing unit

30: servo unit 40: control unit

The present invention relates to a method for discriminating a BD disc, and more particularly, to a BD disc discrimination method capable of accurately determining the type of a BD disc having a low reflectance.

Optical disks are a storage medium for recording and reading data by laser light. In the past, CD and DVD disks were mainly used. However, the use of BD (Blue-ray Disk), which can store a large amount of data, has been recently expanded. . Accordingly, recently released optical recording and reproducing apparatuses are configured to play CDs, DVDs, and BD discs in one device, and for this purpose, an operation of determining the type of optical disc mounted in the optical disc drive before recording and reproducing is performed.

Conventionally used methods for determining the type of optical discs are various, examples of which are described in 'Disk Discrimination Device and Discrimination Method' disclosed in Korean Patent Application Laid-Open No. 1998-71387, and Korean Patent Application Laid-Open No. 1999-42093. Disclosed is a single and dual layer disc identification method in an optical disc drive.

The disc discrimination apparatus of Korean Patent Laid-Open No. 1998-071387 discloses a detection light from a light irradiation means when a disc is mounted on a turntable, and the light receiving means receives the reflected light from the recording surface. The adding means adds and outputs the photoelectric conversion output obtained in the light receiving area of the light receiving means, and the discriminating means receives the output of the adding means to identify the disc according to the difference in the light reflectance of the recording surface.

In addition, the disc identification method of Korean Patent Laid-Open Publication No. 1999-42093 moves the focusing actuator that moves the objective lens up and down so that the signal surface of the optical disc falls within the depth of focus of the objective lens based on the focusing control, and focuses the optical disc. The number of occurrences of the S-curve appearing in the focus error signal during focusing until the actuator is moved to the highest point set in advance is counted, and the single and dual discs are identified according to the occurrences of the S-curve.

However, these conventional disc discrimination methods can be used when the reflectance of the optical disc to be discriminated exceeds a certain level and cannot be used for an optical disc with a very low reflectance such as BD R / RW. In particular, since the BD R / RW dual layer disc has a reflectance less than 10%, it is difficult to extract the S-curve of the focus error signal, and thus disc discrimination is impossible.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problem, and an object of the present invention is to provide a BD disc discrimination method capable of accurately discriminating a BD disc of low reflectance.

In order to achieve the above object, the present invention amplifies a focus error signal and a photo detector sum signal at a first amplification ratio while radiating laser light onto a BD disc, thereby reducing the S-curve of the focus error signal and the BD disc. If the reflectance is detected and the escurve is two, the BD disc is a BD ROM dual layer disc. If the escurve is one and the reflectance is higher than the reference level, the BD disc is a BD ROM single layer disc. When the reflectance is less than the reference level, the focus error signal and the photodetector sum signal are amplified by a second amplification ratio greater than the first amplification ratio to detect an S-curve of the focus error signal, and later detect The BD disc is a BD R / RW dual layer disc when there are two escurves, and the BD disc is a BD R / RW when there is only one escurve detected later. It determines that the paper layer disc.

The first amplification ratio may be set such that the focus error signal and the photodetector sum signal obtained by radiating laser light on the BD disk having the highest reflectance among the BD disks do not exceed the input range by amplification.

In addition, the second amplification ratio is set to 4-5 times the first amplification ratio.

The reference level may be set to a lower limit of the BD ROM single layer disk reflectance or a value close to the lower limit.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. As shown in Fig. 1, an optical recording and reproducing apparatus to which a disc disc discrimination method according to an embodiment of the present invention is applied includes a pickup section 10, an RF processing section 20, a servo section 30, and a control section. And 40.

The pickup section 10 includes a laser diode 11 for emitting laser light having a wavelength of 405 nm, a photo detector 12 for receiving reflected light reflected from a BD disc at four photodetection division planes, and converting them into electrical signals, respectively; And an objective lens (opening ratio 0.85) 14 for focusing the laser light emitted from the laser diode 11 to form a spot on the BD disc, and an actuator 13 for shifting the objective lens 14. Although not shown in the drawings, the optical path includes a collimator lens for converting divergent light into parallel light, a beam splitter for splitting incident light, and the like.

The RF processor 20 generates an RF signal, which is reproduction data, by using the electrical signal transmitted from the photo detector 12 of the pickup unit 10, and focus error signal and photo detector which are signals that detect out of focus. The PD (Photo Detector) sum signal is generated by summing all the electrical signals output from the four photodetection split surfaces formed in 12). The generated focus error signal and the PD sum signal are amplified by a predetermined first amplification ratio or a second amplification ratio and output.

At this time, the first amplification ratio should be set to a size (ie, saturation) so that the focus error signal and the PD sum signal do not exceed the input range by amplification. One amplification ratio can be found. In particular, the manufacturer of the optical recording / reproducing apparatus finds that the focus error signal or amplified by the amplification even if the BD disk having the highest reflectance among the BD disks to be used in the optical recording / reproducing apparatus is mounted when the first amplification ratio is found. Carefully set the first amplification ratio so that the PD sum signal is not saturated.

The second amplification ratio is set in a case where a BD R / RW disc having a low reflectance is mounted, and is set to a value 4-5 times larger than the first amplification ratio. As such, when a low reflectance BD disc is identified, if the focus error signal and the PD sum signal are amplified at a second amplification ratio larger than the first amplification ratio, the reflectance of the BD R / RW is low, so that the electrical signal output from the photo detector 12 is small. The magnitudes of the focus error signal and the PD sum signal output from the RF processor 20 are increased, so that the waveforms of the focus error signal and the PD sum signal can be more easily checked by the controller 40.

The servo unit 30 generates a focusing signal, a drive signal for the spindle, etc. by referring to a focus error signal FE transmitted from the RF processor 20 and a spindle error signal transmitted from the controller 40. .

The controller 40 processes the RF signal and controls the pickup unit 10, the RF processor 20, and the servo unit 30. In particular, the controller 40 detects the S curve from the focus error signal output from the RF processor 20 or multiplies the focus error signal and the PD sum signal to obtain a reflectance, and determines the BD disc by the number of S curves and the magnitude of the reflectance. do.

The S curve is generated when the focus of the laser light passes the recording layer, and the details of the S curve are described in Korean Patent Laid-Open Publication No. 2005-0031010. The reflectance varies depending on the type of BD disc. In the diagram of FIG. 2, which shows the reflectance of the BD disc to 405 nm laser light, the reflectance of the BD R / RW is lower than that of the BD ROM. It can be seen that low.

A method of discriminating a BD disc according to an embodiment of the present invention will be described with reference to FIG. The manufacturer of the optical recording and reproducing apparatus stores the first and second amplification ratios in a memory (not shown) when the product is released, and sets the amplification ratios of the focus error signal and the PD sum signal to the first amplification ratio (50).

In this state, when the user mounts the BD disc in the optical disc drive (not shown), the optical recording / reproducing device drives the laser diode 11 while driving the actuator 13 to lower and then raise the objective lens 14 to 405 nm. Allow laser light of wavelength to be emitted 52. When the laser light is reflected from the BD disc, the RF processor 20 amplifies and outputs the focus error signal and the PD sum signal at a first amplification ratio. The controller 40 detects the S curve from the focus error signal while monitoring the focus error signal, and multiplies the focus error signal and the PD sum signal to measure the reflectance of the BD disc (54).

In operation 56, it is determined whether two S-curves are detected. If two S-curves are detected, this means that there are two recording layers instead of the low-reflectance BD disc, and it is determined that the mounted BD disc is a BD ROM dual layer disc (70). However, if there are not two S-curves, it is determined whether the reflectance is greater than or equal to the reference level (58). At this time, the reference level is preferably set to 35% or the lower reflectance lower limit of the BD ROM single layer disc.

If the reflectance exceeds the reference level in step 58, the BD disc mounted in the optical disc drive is recognized as a BD ROM single layer disc (72). If the reflectance is less than the reference level, the amplification ratio of the focus error signal and the PD sum signal is determined to be the second. The amplification ratio is set (60). Then, the actuator 13 is driven again to lower and then raise the objective lens 14 to drive the laser diode 11 to emit 405 nm wavelength laser light (62). When the laser light is reflected from the BD disc, the RF processor 20 amplifies and outputs the focus error signal and the PD sum signal at a second amplification ratio. The controller 40 detects the S curve from the focus error signal while monitoring the focus error signal. If there are two S-curves (64), if the two S-curves are two, the mounted BD disc is recognized as a BD R / RW dual layer disk (68). / RW is recognized as a single layer disk (66). The reason for this determination is that the BD disc installed in the process of 50-58 is not a BD ROM. Therefore, it can only be a BD R / RW. If there are two S-curves, the dual-layer disc and the S-curve have one. This is because a single disc means a single layer disk.

For reference, although not shown in FIG. 3, when the mounted BD disc is confirmed to be a BD R / RW, disc information may be used to further distinguish whether the mounted BD disc is a BD R or a BD RW.

As described in detail above, if the mounted BD disc is a low reflectivity disc, the type of BD disc is determined by a focus error signal obtained by increasing the amplification ratio than before, so that a disc having low reflectance can be accurately determined.

Claims (4)

A laser beam is emitted onto the BD disc to amplify a focus error signal and a photo detector sum signal at a first amplification ratio to detect an S-curve of the focus error signal and a reflectance of the BD disc. If the escurve is two, the BD disc is a BD ROM dual layer disc. If the escurve is one and the reflectance is higher than or equal to the reference level, the BD disc is determined to be a BD ROM single layer disc. When the reflectance is less than the reference level, the focus error signal and the photodetector sum signal are amplified by a second amplification ratio greater than the first amplification ratio to detect an S-curve of the focus error signal. The BD disc is a BD R / RW dual layer disc if there are two escurves detected later, and the BD disc is determined to be a BD R / RW single layer disc if there is only one escurve detected later. Discrimination method The method of claim 1, The first amplification ratio is set so that the focus error signal and the photodetector sum signal obtained by radiating laser light on the BD disk having the highest reflectance among the BD disks do not exceed the input range by amplification. Discrimination method The method of claim 1, And the second amplification ratio is set to 4-5 times the first amplification ratio. The method of claim 1, And the reference level is set to a lower limit of the BD ROM single layer disc reflectance.

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