KR100424491B1 - Method for discriminating a kind of optical disk and focus control method using the method - Google Patents

Abstract

The present invention relates to an optical disc identification method and a focus control method using the same. An optical disc identification method according to the present invention includes a first step of raising the focus lens after lowering the focus lens during focus search of the optical disc, and starting the counting of the interval simultaneously with the rise of the lens; Detecting a focus ok signal for a predetermined time; Storing the counted interval value again upon detection of a focus ok signal, restarting the count of the intervals, increasing the number of focus oks by one, storing the value, and detecting and storing the amount of reflection of light reflected from the optical disk; Steps; And repeating the first and second steps for a predetermined time period, and then identifying a type of the disc according to the stored interval counter value, the focus ok number value, and the reflection amount. The method for controlling a focus of a disk according to the present invention includes detecting and storing a focus control signal value at the time of detecting a focus ok signal in a type identification process of an optical disk, and storing the focused focus of a predetermined layer to be focused on the disk. Setting an upper limit value and a lower limit value of a focus control signal for focus search based on the control signal value; And searching for a focus on signal while increasing the focus control signal value from the set lower limit value to an upper limit value.

Description

Optical disc identification method and focus control method using the same {Method for discriminating a kind of optical disk and focus control method using the method}

The present invention relates to an optical disc identification method and a focus control method using the same. More particularly, the present invention relates to an optical disc detection method and a focus control method using the same, and to detect an optical disc using the detected parameters. And a focus control method for detecting a value of a focus control signal at the time of occurrence of a focus ok signal in the optical disc identification process and using the detected focus control signal value in focus control.

Optical disc media have evolved from CD-DA, CD-ROM and the like to CD-R and CD-RW recordable standards, starting with CD. Recording capacity is also developing from the CD series to the DVD series with the development of laser diodes. Since a CD and a DVD coexist, it is common for a set for playing a DVD to play a conventional CD-based disk medium together. In particular, a hybrid disc has been commercially available in which both DVD and CD can be played in one disc. In particular, SACD (Super Audio CD) is included in the standard to enable hybrid discs. In order to be able to reproduce such a plurality of types of discs in one set, accurate determination of the type of disc has become an important problem. One way to solve this problem is the method proposed in US Pat. No. 6,278,672.

1 is a block diagram of a disc reproducing apparatus shown for explaining a general operation of a disc player. There is a spindle motor 12 and a spindle driver 14 for driving the spindle motor 12 to rotate the disk 10 and a pick-up attached to the sled 15. There is a sled motor 18 and a sled driver 20 that drives the sled motor 18 to move up 16. The spindle motor 12 or the spindle driver circuit 14 sends a frequency generator signal (FG) indicating the rotation of the spindle to the servo system 18. There is a focusing actuator (not shown in the figure) that moves an objective lens in the pickup 16 in the direction of the disk rotation axis, and a focusing driver 24 that drives the actuator. There is a tracking actuator (not shown in the figure) for moving the lens in the disc radial direction and a tracking driver 22 for driving the actuator. The pickup 16 detects the data recorded on the rotating disk 10 and outputs a high frequency (HF) signal. The HF signal is received and amplified and the focus error required by the servo system 28 A signal separation unit 26 for generating a focus error (FE) signal, a tracking error (TE) signal, a PI (Photo Integrity) signal (a signal made by using a sum of ABCD signals of PD), and the signal separation unit 26; There is a servo unit 28 which controls the spindle driver 14, the sled driver 20, the tracking driver 22 and the focusing driver 24 using the signals received from the unit 26. In addition, there is a digital signal processor 30 for processing the HF signal of the signal separation block 26 to produce a video signal and an audio signal. The controller 32 is configured to control the operation of the entire system.

FIG. 2 is a diagram illustrating a signal waveform detected by a method proposed in US Pat. No. 6,278,672 as a conventional optical disc identification method. The focus control signal FCS represents a control signal input to the focus driver 24 (see FIG. 1). When the FCS signal is at 0, the objective lens does not move. If the value is negative, the objective lens moves away from the disc. If the value is positive, the objective lens moves closer to the disc. It indicates losing. Through the control of the controller unit 32 (see FIG. 1) and the servo system 28 (see FIG. 1), the FCS signal moves the objective lens so that the FE signal and the PI signal change. The server system 28 (refer to FIG. 1) generates a focus ok (FOK) signal using the FE signal and the PI signal. At this time, in order to generate the FOK signal, the FE threshold signal (Threshold_FE) and the PI threshold signal (Threshold_PI) are used internally for the threshold of each signal. If the level of each signal exceeds the threshold signal, a FOK signal is generated. At the same time, an interval between FOKs is calculated using an internal interval counter (not shown).

3 is a flowchart illustrating a method disclosed in US Pat. No. 6,278,672 as a conventional optical disc identification method.

When the disc's identification-related operation starts, the focus lens is lowered by driving the focus driver 24 (see FIG. 1). At this time, the interval counter and the focus ok number counter, which are the main values of the disc identification, are cleared (step S10). The pickup is lowered for a predetermined time and then the focus lens is raised (steps S12 to S14). In this case, the purpose of the lowering is to move the objective lens to the position where the disk surface can be detected in FIG. 4. The focus ok signal FOK is detected while the focus lens is raised. If the first FOK signal is not detected, the detection operation is repeated for a predetermined value (steps S16 and S24). However, the focus ok number counter does not increase at this time. If the first FOK signal is detected, the interval counter starts to increase, and the focus ok number counter also increases by one. Subsequently, the FOK signal is searched and the number of all FOK signals existing within a predetermined time period and the distance between each FOK signal are measured (steps S16, S18, S20, S22, and S24). When the measurement is completed, the disk identification operation is completed after identifying the disk by the FOK signal number and the interval counter value.

4 shows the mechanical distance between the disk and the objective lens. The distance from the surface to the signal layer is 0.6 mm for a DVD disc and 1.2 mm for a CD. The distance from the objective lens surface to the disk surface for accurate focusing on the signal plane on the DVD, the distance from the objective lens surface to the disk surface for accurate focusing on the signal surface on the CD, B is the difference between A and B, and the objective lens is The distance that can be moved is D for DVD and E for CD. A to E can vary depending on the pickup.

In the prior art, it is a DVD when the distance counted by the interval counter is about 0.6 mm, and it can be discriminated by a CD when it is about 1.2 mm.

There can be many unexpected problems on a real system. For example, in the standard, the interlayer distance of DVD and CD is 0.6mm and 1.2mm, respectively, but for A, B, C, D, and E, the pick-up and set maker have to set the manufacturing tolerance as about 0.2mm. none. In addition, the accuracy of the focus control signal (FCS) voltage should be determined in consideration of the output voltage tolerance of the chip used in manufacturing, and the tolerance of power supply and resistance of 20%.

In addition, as the CD has been developed in various standards such as CD-R and CD-RW, and DVD has been developed in various standards such as DVD Single, DVD Dual, Hybrid, DVD-R, DVD-RW, and the like, the types of discs are becoming more diverse. In each standard, reflectivity on the disc recording surface is defined. Reflectance varies from 0.15% to 85%.

In recent years, if the disc specification does not meet the disc specification, mechanical tolerances or reflectance tolerances may be greater, and the situation may be further exacerbated by dirt and scratches depending on the use environment. Considering all the above situations, the possibility of the existence of a disc that is not disc identified in the conventional manner increases.

In particular, the above-described method must detect the surface layer to measure the distance to the internal signal layer and determine the disk. However, when the tolerance generated in A of FIG. 4 is larger than D-0.6 mm, the surface of the disc may not be detected. If the tolerance of A is larger than D-0.6 mm, the DVD lens may not be used. There is a case where the distance from the surface to the signal layer cannot be measured because the recording layer is not detected. In addition, there is also the possibility that the reflectivity at the surface is so small that it will not be detected by dirt, scratches, or the like. In this case, if the disk is detected only by the conventional method, an error may occur in the disk detection. Alternatively, excessive mechanical precision may be required to solve the above problems, and playability of a disc outside a specific specification may be deteriorated.

Furthermore, there is a problem that it is difficult to accurately focus the objective lens on the signal layer on the disc when the disc detection fails. In this case, there is a high possibility that the time required for playing the game may be increased after abandoning the play of the disc or attempting to focus the game several times.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and the type of disc is identified even when the reflection on the surface of the optical disc is not detected or the recording layer of the CD layer is not reflected due to the various situations described above. Its main purpose is to provide an optical disc identification method.

Another object of the present invention is to determine the presence or absence of the optical disk surface layer, to accurately determine the position of the actual signal layer, to determine the disk level by judging the signal level of the signal layer in detail to determine the parameters of the high frequency (HF) processing system. I want to use it for setup.

It is still another object of the present invention to provide a focus control method of an optical disc capable of accurately focusing a desired position at the time of focusing by using the position of the actual signal layer determined at the time of optical disc identification.

The optical disc identification method according to the present invention for achieving the above object is a first step of raising the focus lens after lowering the focus lens during the focus search of the optical disk, and at the same time as the rise of the lens and starting the interval counting; ; Detecting a focus ok signal for a predetermined time; Storing the counted interval value again upon detection of a focus ok signal, restarting the count of the intervals, increasing the number of focus oks by one, storing the value, and detecting and storing the amount of reflection of light reflected from the optical disk; Steps; And repeating the first and second steps for a predetermined time period, and then identifying a type of the disc according to the stored interval counter value, the focus ok number value, and the reflection amount.

In addition, the focus control method of the disk according to the present invention, in the identification process of the type of the optical disk, the detection of the focus control signal value when the focus OK signal is detected and stored, and the stored focus of the predetermined layer to be focused on the disk Setting an upper limit value and a lower limit value of a focus control signal for focus search based on the control signal value; And searching for a focus on signal while increasing the focus control signal value from the set lower limit value to an upper limit value.

According to the present invention configured as described above, the logic for measuring the amount of reflection in addition to the focus error signal (FOK) made by using a focus error signal and a PI (Photo Integrity) signal generated on the reflection surface generated when disc determination Then, the measured amount of reflection is compared with the amount of reflection in the focus ok signal FOK at a specific level or another position to determine whether the surface layer is detected, and when the surface layer is not detected, the first layer is recognized as the signal layer. The measured reflection amount is used to determine the type of detailed disc such as a DVD or a CD. In addition, a counter value for the focus ok signal FOK position generated when the focus ok signal FOK is measured, a value corresponding to a counter value of a start point of a focus control signal FCS, and a focus control corresponding to a position of each counter value Stores the signal (FCS) voltage. Focusing is performed by finding and focusing around the position where the focus ok signal FOK is generated by using the measured counter value and the focus control signal voltage for focusing on the determined position of the signal layer. do.

1 is a block diagram of a disc reproducing apparatus shown for explaining a general operation of an optical disc player.

2 is a timing diagram for explaining a conventional optical disc identification method.

3 is a flowchart illustrating a conventional optical disc identification method.

4 is a diagram showing the mechanical distance between the disk and the objective lens.

5A and 5B are timing diagrams for explaining an optical disc identification method according to the present invention.

6 is a flowchart illustrating an optical disc identification method according to a preferred embodiment of the present invention.

7 is a flowchart for explaining a disk identification step in the disk identification method of FIG.

8 is a flowchart for explaining an optical disk focus control method according to the present invention.

※ Explanation of code for main part of drawing

10: multilayer disk 12: spindle motor

14: spindle driver 15: sled

16: pickup 18: sled motor

20: Sled Driver 22: Tracking Driver

24: focusing driver 26: signal separation unit

28: servo system 30: digital signal processing unit

32: controller

Hereinafter, an optical disc identification method and a focus control method using the same according to a preferred embodiment of the present invention will be described with reference to the accompanying drawings.

First, an optical disk identification method according to a preferred embodiment of the present invention will be described in detail with reference to FIGS. 5 to 7.

5A and 5B are timing diagrams for explaining an optical disc identification method according to the present invention.

In the drawings, the description of the signal waveform described with reference to FIG. 2 will be omitted. In the drawing, the added or changed portion latches a point signal at a critical point during focus search (movement of the objective lens up and down to find a desired point when disc determination or focusing the objective lens on the disc). The focus control signal (FCS) latch signal (P0, P1, P2, etc.), an interval counter signal (counting the time points of the important points). A focus control signal value storage unit for storing the voltage of the focus control signal FCS at the time of occurrence of the important signal points P0, P1, P2, ... during the focus search, and a level of the reflection amount generated during the focus search; A reflection peak value detection and storage unit for storing the value.

6 is a flowchart illustrating an optical disc identification method according to a preferred embodiment of the present invention. In the flow of the optical disc identification method according to the embodiment of FIG. 6, the focus control signal (FCS) value storage, the reflection peak value detection and storage step (step S160) are substantially added as compared with the conventional FIG. 3. The count start time of the counter is changed so that the interval counter related to the ok signal FOK is counted from the time when the focus driver starts the focus raising operation.

Referring to the schematic operation, the focus lens is lowered by driving the focus driver 24 (see FIG. 1) when the disc identification related operation is started. At this time, the interval counter (Interval Counter) and the focus ok number counter (FOK number counter), which are main values of the disc identification, are cleared (step S100). After the pickup is lowered for a predetermined time, the focus lens is raised (steps S110 to S120). At the same time as the focus lens is raised, the interval count is started and the count value is increased (step S130).

Then, the focus ok signal FOK is detected while the focus lens is raised (step S140). If the FOK signal is not detected at this time, it is determined whether a predetermined predetermined time has elapsed (step S170), and if the predetermined time has not elapsed, the FOK signal detecting operation of step S140 is repeated.

When the FOK signal is detected in step S140, the incremented interval counter value is stored up to that time, the interval counter is cleared (the interval counter value is set to 0), the count value of the interval counter is increased, and the FOK counter value is increased by one. To increase (step S150).

Then, the focus control signal FCS value is detected and stored at the time point when the FOK signal is detected, and the reflection peak value is detected and stored at the time point (step S160).

By repeating the operations of steps S140 to S170, the number of all FOK signals existing within a predetermined time period, the interval between each FOK signal, the FCS value, and the reflection peak value are detected. Thereafter, when a predetermined time elapses, the disk identification operation is completed after identifying the disk by the detected value (step S180).

As described above, the FOK detection operation (steps S140 to S170) is repeated, and the focus lens is searched with the focus control signal FCS of FIG. 5A, and the interval therebetween at positions of important signal points such as P0, P1, and P2 ( Interval), the focus control signal (FCS) value, and the reflection peak value are measured. The measured values are illustrated in Table 1 below.

point Thickness (mm) FCS value Reflection peak value P0 None FDV0 None P1 L1 FDV1 RP1 P2 L2 FDV2 RP2 P3 L3 FDV3 RP3

The terms labeled None in Table 1 indicate nonexistent values. In Table 1, the interval and the reflection peak value among the detection values are used for disc determination, and the focus control signal (FCS) value is used for focusing by determining the position of the disc layer simultaneously with disc determination.

5B is a diagram illustrating a method of detecting a reflection peak value. This method uses the PI signal and the FE signal used in the conventional focus servo method. The R1 value that takes the peak-to-peak value of the focus error signal FE and the R2 value that takes the maximum value of the PI signal are illustrated in a section where the FOK signal is at a high level. These values are highly relevant to the disk's reflection and are used to calculate the reflection peak. Here, the FE signal and the PI signal are appropriately filtered values.

The method illustrated here may use R1, R2 by appropriately calculating either or both values. However, the value should be set at the threshold values of the disc type and layer value through the specification of the reflection amount generated on the signal surface of the DVD series and the CD series and the reflection amount generated on the surface of the disc. For reference, the reflectance ratio of the disk surface layer is 10% or less, the reflectance of the signal surface of the single-sided DVD (DVD Single) is 45-85%, and the reflectances of the disk surface and the signal surface are varied. In other words, it is necessary to determine the boundary values in consideration of margin, precision of the measurement system, and tolerances.

Table 2 exemplarily shows values detected by the present invention in the case of a hybrid disc (SACD).

Disk (hybrid) point Thickness (mm) FCS value Reflected peak value Conventional detection Detection of the present invention None P0 None FDV0 None None None Surface layer P1 Not detected Not detected Not detected Not detected Not detected DVD layer P2 Lx FDV2 RP2 Surface layer DVD layer CD layer P3 0.6 FDV3 RP3 DVD layer CD layer

Hybrid discs have a DVD layer 0.6 mm from the surface layer and a CD layer down 0.6 mm further down. In this case, the detected values are as shown in Table 2. However, in order to show the difference in the operation of the proposed method, it is assumed that the surface layer is not detected due to some factor.

The Disc (Hybrid) in the first column indicates the positions of the layers that actually exist in P0 to P3. The spacing represents the distance of the value counted by the spacing counter when no surface layer was detected. In this case, Lx represents the distance to the first layer, that is, the DVD layer, after the focus search starts. In the conventional detection method, the DVD layer is recognized as the surface and the CD layer is recognized as the DVD layer without determining the situation where the surface layer is not detected.

In the present invention, the method of determining whether or not the surface detection is discriminated will be described. In the method 1, if the reflection level of the first detected layer is equal to or greater than the upper surface layer reflection upper limit (predetermined value), the first layer is not the disk surface. Recognize as a surface and judge in the same way as the conventional method. Method 2 uses the ratio of the first reflection value to the second reflection value and recognizes that the first layer is the signal layer if the ratio is above the upper limit value (predefined value) of the ratio. In this case, since the reflectance of the DVD layer is higher than that of the CD layer, the DVD layer can be easily discriminated. Conversely, if the reflectance of the first layer is lower than the second layer, the first layer is recognized as the surface layer. Method 3 can be implemented in various ways such as applying both method 1 and method 2. If it discriminates as mentioned above, it can detect like Table 2 of this invention.

Table 3 exemplarily shows values detected by the present invention in the case of a DVD. In Table 3, the values were detected in the same manner as in Table 2.

Disc (DVD) point Thickness (mm) FCS value Reflected peak value Conventional detection Detection of the present invention None P0 None FDV0 None None None surface P1 Not detected Not detected Not detected Not detected Not detected DVD layer P2 None FDV2 RP2 Not detected DVD layer

Since there is only one layer detected in Table 3, the above-described method 2 and method 3 cannot be used and can only depend on method 1. According to the scheme 1, the P2 position can be recognized as a DVD layer or a CD layer. In addition, DVD and CD can be distinguished by specifying a boundary that distinguishes the reflection of the DVD and CD signal layers using the DVD laser diode. If the reflection value of the DVD layer is less than the upper surface layer reflection upper limit, then the disk can be judged as a disk without an internal signal layer.

In the worst case, if the reflection of the CD layer cannot be measured by the DVD laser diode due to various possibilities, the method performed in FIG. 5A should be repeated using the CD laser diode.

9 illustrates a method of identifying a disc through the above process.

First, the presence or absence of the surface layer is determined by detecting the surface layer (step S220), and if there is a surface layer, the disk is identified in the same manner as in the conventional method. On the other hand, if it is determined in step S120 that there is no surface layer, it is determined whether the number of detected FOK signals is two (that is, two counted layers) (step S210).

When it is determined in step S220 that the number of FOK signals is two, the interval levels are compared to determine whether they are a DVD dual or a hybrid disk (steps S230 to S250). In step S230, it may be determined whether the interval between the FOK signals is close to 0.6 mm, and the DVD dual and the hybrid discs may be discriminated. In this case, the distance between the FOK signals is close to 0.6 mm.

If it is determined in step S220 that the number of FOK signals is not two, it is determined in step S260 whether the number of FOK signals is one. If the number of FOK signals is one, CD and DVD sequences are determined by comparing the reflectances of the signal layers (steps S270 to S290).

On the other hand, if it is determined in step S260 that the number of FOK signals is 0 (that is, there are no layers), the process is considered in consideration of the possibility of not being a disc and the situation that a CD layer has not been detected (step S300). Through the above process, the identification of the disk can be implemented.

If the surface layer or the CD layer cannot be detected due to the above factors in the disc identification process, the focus on (focusing on the focus lens on the signal surface) is performed by the focus search in the same manner as before. Operation at) is difficult to accurately achieve the desired layer. For example, in order to focus on the CD layer of a hybrid disc, it is important not to focus on the surface of the disc and the DVD layer. However, if problems such as tolerances occur, the exact location of the required floor is essential. In particular, in order to reduce the tolerance of the focus driver, it is necessary to use the focus control signal (FCS) value in the measurement step. In addition, there is a need for a method of conducting a focus search near a desired position of several layers occurring in the disk layer. At this time, the focus can be focused on the correct floor by performing the focus search near the desired focus control signal value using the focus control signal FCS value measured in the method of the present invention.

8 is a flowchart for explaining an optical disk focus control method according to the present invention.

First, in the state of identifying the optical disk as shown in Fig. 6, the interval counter value, the FOK counter value, the FCS value and the reflection peak value at each focus ok time point are detected and stored in the storage means.

In this state, the focusing operation reads the FCS value of the focus-on predetermined layer to be focused from the storage means and sets the FCS lower limit (focus search start point) and the upper limit (focus search end point) for focus search based on the read FCG value. do. Then, when the FCS signal value reaches the set upper limit while outputting the lower limit of the set FCS signal as an initial focus search value to the focus driver, and increasing the value of the FCS signal applied to the focus driver until the focus on signal is detected. Repeat (step S400). Thereafter, the above-described step focus search operation is repeated a predetermined number of times in order to reduce the possibility of a focus-on detection error (steps S410 to S450).

On the other hand, the present invention is not limited to the above-described embodiment, but can be carried out by various modifications and variations within the scope not departing from the gist of the present invention, the technical idea that such modifications and variations are also applied to the following claims Should be regarded as belonging to

As described in detail above, according to the present invention, the playability of a set is prevented by preventing a disc detection error that may occur due to a defect that may occur in a disc and a possible tolerance within the set and a focus on error that may occur due to the error. Can be increased. In addition, the disc identification time can be reduced because the interval between the focus ok signals and the reflection peak value are measured and used for disc identification at disc detection.

Claims (10)

When a focus ok signal generated by using a focus error signal and a PI (Photo Integrity) signal at the time of focus search of the optical disk is detected, the amount of reflection of the light reflected from the optical disk is detected, and the type of the optical disk is determined using the reflected amount. Optical disc identification method, characterized in that. The method of claim 1, Counting the number of occurrences of the focus ok signal, an interval between a start point of rise of a focus control signal and the first focus ok signal generated, and an interval between the generated focus ok signals; An optical disc identification method characterized in that it is used for disc type determination. The method of claim 1, And determining the surface layer of the optical disk using the reflection amount, and recognizing the first layer as a signal layer when the surface layer is not detected. The method according to any one of claims 1 to 3, And the reflection amount is detected using peak-to-peak values of the focus error signal and the PI signal. A first step of raising the focus lens after descending the focus lens during the focus search of the optical disk and starting the interval count at the same time as the lens rises; Detecting a focus ok signal for a predetermined time; Storing the counted interval value again upon detection of a focus ok signal, restarting the count of the intervals, increasing the number of focus oks by one, storing the value, and detecting and storing the amount of reflection of light reflected from the optical disk; Steps; And repeating the first and second steps for a predetermined time period, and then identifying the type of the disc according to the stored interval counter value, the focus ok number value, and the reflection amount. Optical disc identification method. The method of claim 5, And determining the surface layer of the optical disk using the reflection amount in step 4, and if the surface layer is not detected, recognizes the first layer as a signal layer and identifies the type of the disk. The method of claim 6, And identifying the disc as a DVD dual or a hybrid disc according to the level of the interval when the number of stored focus okays is two in step 4. The method of claim 6, And if the number of stored focus okays is one in step 4, determining the level of the reflection corresponding to the level of the disc to identify the DVD and the CD. The method according to any one of claims 5 to 8, And the reflection amount is detected using peak-to-peak values of the focus error signal and the PI signal. Detects and stores the focus control signal value at the time of detecting the focus ok signal in the process of identifying the type of optical disc, Setting an upper limit value and a lower limit value of a focus control signal for focus searching based on the stored focus control signal value of a predetermined layer to be focused on the disk; And searching for a focus on signal while increasing the focus control signal value from the set lower limit value to an upper limit value.