KR100268383B1 - Focus Offset Corrector - Google Patents

Abstract

The present invention relates to an apparatus for correcting a focus offset for a focus error signal in an optical disc player, wherein the apparatus for correcting a focus offset receives a focus error signal and performs a calculation for correcting the focus offset to output a correction signal. And a correction unit for correcting a focus offset of the input focus error signal according to the correction signal of the controller. When the focus offset of the focus error signal is corrected for two times, the focus error signal during playback moves around the average value of the focus error signal when the focus is off. The focus servometer operates stably even in the defect section.

Description

Focus Offset Corrector

The present invention relates to an apparatus for correcting a focus offset for a focus error signal in an optical disc player, and more particularly, to an apparatus for correcting a focus offset for a focus error signal over a secondary. It is about.

When an optical disc (Laser Disc; LD) is mounted on the optical disc player, the focus servo corrects the focus offset of the optical disc by measuring the focus error signal FE in the focus off state. The correction process of the focus offset will be described with reference to FIG. 1.

1 is a configuration diagram illustrating a focus servo controller for correcting a focus offset of a conventional focus error signal. The LD is mounted on the optical disc player, and the FE detected in the focus-off state is input to the FEA (Focus Error Average) calculator 11. The FEA calculator 11 calculates an average value FEA by averaging the FE input for a predetermined time determined by the controller 12 by the control of the controller 12. The controller 12 reads the average value FEA calculated by the FEA calculator 11, determines the value Fofst for correcting the focus offset, and outputs it to the Fofst storage unit 13. The Fofst storage unit 13 stores the received Fofst. After that, the focus is turned on, and the optical disc player enters the reproduction mode of the LD. At this time, the detected FE is input to the subtractor 14. The subtractor 14 receives and subtracts the input FE and the Fofst stored in the Fofst storage unit 13 in the focus off state. This subtracted value (FE-Fofst) is input to the focus servo operator 15, and the focus servo operator 15 performs servo operation so that the actuator of the pickup not shown so that the value of the FE-Fofst becomes '0'. Outputs the drive signal for driving to the actuator. Thus, the actuator of the pickup is driven in accordance with this driving signal, and through this process, the focus offset for the focus error signal is corrected.

However, although the focus offset correction should be sufficiently performed through the above-described process, the value Fofst for correcting the focus offset due to the aberration of the actual optical system is different from the LD playback mode in the focus off state and after the focus on state. Have Therefore, in the LD regeneration mode, the FE input as shown in FIG. 2A shown in the defect section of the LD has a momentarily changed value, and energy such as a hatched portion is transmitted to the actuator. Then, after the defect section, it can be seen that the FE is greatly shaken to correct this energy. At this time, if the level of the required FE is too large, defocus is induced and eventually a focus drop results in a problem that the focus servo is unstable.

Therefore, in order to solve this problem, in the present invention, as shown in FIG. 2B, the FEA and Fofst in the focus-off state coincide with each other so that the focus servo system can be stably operated. An object of the present invention is to provide a focus offset correction device that performs focus offset correction on an error signal.

1 is a configuration diagram illustrating a focus servo controller for correcting a focus offset of a conventional optical disc;

FIG. 2A is a waveform diagram showing a conventional focus error signal in the defect section of LD; FIG.

2B is a waveform diagram illustrating a focus error signal according to the present invention in the defect section of LD;

3 is a configuration diagram illustrating a focus servo controller for correcting a focus offset of a focus error signal to which the present invention is applied;

4 is a flowchart illustrating a flow of focus offset correction in a focus servo controller to which the present invention is applied;

5 is a flowchart illustrating an operation of the controller 21 for correcting the second focus offset.

6 is a waveform diagram illustrating a focus error signal that is changed through focus offset correction according to the present invention;

<Description of Main Parts of Drawing>

10, 20: 1st, 2nd Supplementary Government 11: FEA Department

13, 22: Fofst storage 21: controller

14, 23: subtractor 15: focus servo calculation unit

A feature of the present invention for achieving the above object is in an apparatus for correcting a focus offset for a focus error signal in an optical disc player, receiving a focus error signal and performing an operation for correcting the focus offset to output a correction signal. A focus offset correction apparatus for correcting a focus error signal includes a controller for correcting a focus offset with respect to a focus error signal received according to a controller and a correction signal of the controller.

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

3 is a block diagram illustrating a focus servo controller for correcting a focus offset of a focus error signal to which the present invention is applied. The focus servo controller of FIG. 3 includes the conventional focus servo controller shown in FIG. 1, and includes a controller 21 for determining a value Fofst2 for correcting a focus offset in the reproduction mode of the LD, and a controller 21. And a second correction unit 20 for correcting the focus offset in accordance with the correction signal. The second correction unit 20 subtracts the output values of the second Fofst storage unit 22 and the first subtracter 14 and the output values of the second Fofst storage unit 22 and the focus servo operation unit (Fofst2). And a second subtractor 23 outputted to 15). The operation of the focus servo controller configured as described above will be described with reference to FIGS. 4 and 5.

4 is a flowchart illustrating a schematic flow of performing focus offset correction in the focus servo control unit to which the present invention is applied. As shown, the laser diode for detecting the focus error signal is in an on state (step 401), and the focus error signal FE1 is input to the FEA calculator 11 in the focus off state (step 402). The FEA calculation unit 11 calculates an average value FEA1 by averaging the FE1 input for a predetermined time determined by the controller 21 by the control of the controller 21. The controller 21 reads the average value FEA1 calculated by the FEA calculator 11 and determines it as a value Fofst1 for focus offset correction (step 403) to determine the first Fofst storage unit (1) of the first correction unit (10). 13). The first Fofst storage unit 13 stores the received Fofst1. After that, the focus is turned on (step 404), and the optical disc player enters the reproduction mode of the LD. When the LD is in the playback mode, the focus servo controller of FIG. 3 performs an operation for correcting the focus offset (step 405). That is, the focus error signal FE2 detected in the reproduction mode is input to the first subtracter 14 and the FEA calculator 11 of the first correction unit 10. In addition, the first subtractor 14 receives Fofst1 from the first Fofst storage unit 13. Thus, the first subtractor 14 subtracts the input FE2 and Fofst1 and outputs the subtracted value FE2-Fofst1 to the second subtractor 23 of the second compensator 20. Meanwhile, the FEA calculator 11 averages the input FE2 for a predetermined time determined by the controller 21 under the control of the controller 21, calculates an average value FEA2, and outputs the average value FEA2 to the controller 21. The controller 21 determines whether the second focus offset should be corrected by the second correction unit 20 by determining the deviation between the input FEA2 and Fofst1, and with reference to the flowchart of FIG. Explain in more detail.

5 is a flowchart illustrating a process of performing the controller 21 to correct the second focus offset. That is, the controller 21 controls the FEA calculator 11 to receive the average value FEA2 of FE2 in the playback mode (step 501), and to correct the deviation and the preset second focus offset (Fofst2). Are compared (step 502). If the deviation is smaller than Fofst2 as a result of the comparison, the controller 21 recognizes that FEA2 in the playback mode and Fofst1 in the focus-off state match, and does not perform an operation for correcting the second focus offset. That is, in this case, the focus servo controller operates in the same manner as in the case of the conventional first focus offset correction described above. Thus, the subtracted value FE2-Fofst1 input to the second subtractor 23 of the second correction unit 20 is input directly to the focus servo calculation unit 15. The focus servo operator 15 performs a servo operation and outputs a driving signal to the actuator for driving the actuator of the pickup, not shown, so that the value of FE2-Fofst1 becomes '0'. Thus, the actuator of the pickup is driven in accordance with this drive signal, and the focus offset is corrected as the first order.

If the deviation of the comparison result in step 502 is greater than Fofst2, the controller 21 recognizes that the FEA2 in the playback mode and the Fofst1 in the focus-off state are inconsistent, and performs an operation for correcting the second focus offset. . Thus, the controller 21 compares the sizes of FEA2 and Fofst1 (step 503). As a result of comparison, if FEA2 is greater than Fofst1, the controller 21 increases the value of Fofst2 (step 504). If FEA2 is smaller than Fofst1, the controller 21 decreases the value of Fofst2 (step 505). The controller 21 performs operation 501 again after performing steps 504 and 505. Thus, the FEA calculator 11 calculates the average value FEA2 of the FE2 input again and outputs it to the controller 21, and the controller 21 calculates the deviation again and reconstructs the Fofst2 adjusted in step 504 or 505 again. Compare (step 502). Thus, if the deviation is greater than Fofst2 as a result of the comparison, the controller 21 repeats the process again from step 503, and this process is repeatedly performed until the deviation is smaller than Fofst2. Therefore, if the deviation is less than Fofst2, the controller 21 ends this routine, and determines the adjusted Fofst2 as a value for the second focus offset correction, and outputs it to the second Fofst storage section 22. FIG. The second Fofst storage unit 22 outputs Fofst2 to the second subtractor 23, and the second subtractor 23 subtracts the values FE2-Fofst1 and Fofst2 input from the first subtractor 14 to focus focus calculation unit. Output to (15). The focus servo operator 15 performs a servo operation and outputs a drive signal for driving the actuator of the pickup, not shown, so that the value of the input FE2-Fofst1-Fofst2 is '0' to the actuator. Thus, the actuator of the pickup is driven in accordance with this drive signal, and the focus offset is corrected as the first and second orders.

6 is a waveform diagram illustrating a focus error signal FE that is changed through focus offset correction according to the present invention. Able to know.

As described above, if the focus offset of the focus error signal is corrected over the second order, the focus error signal FE2 during playback moves around the average value Fofst1 of the focus error signal when the focus is off. The focus servo meter operates stably even in the defect section of the.

Claims (7)

An apparatus for correcting a focus offset with respect to a focus error signal in an optical disc player, the method comprising correcting a focus offset by receiving a focus error signal according to a focus off state and a focus on state. A controller for outputting a plurality of correction signals; And a correction unit for correcting a focus offset of the focus error signal received in response to a correction signal of the controller a plurality of times. The display apparatus of claim 1, wherein the correction unit comprises: a first correction unit configured to correct a focus offset according to a correction signal in a focus off state; And a second correction unit for correcting the focus offset in accordance with the correction signal in the optical disc reproducing mode after the focus-on state. The display apparatus of claim 2, wherein the first compensation unit comprises: a first storage unit configured to receive and store a value F1 for the first correction of the focus offset from the controller; And a first subtractor which receives a focus error signal (FE2) detected in a focus-on state and subtracts and outputs a value F1 for correcting the focus offset. 4. The controller of claim 3, wherein the controller averages the focus error signal FE1 detected in the focus off state for a predetermined period of time and determines the average value as the value F1 for the first order correction of the focus offset. Focus offset correction apparatus characterized in that the output to the first storage. The display apparatus of claim 2, wherein the second compensation unit comprises: a second storage unit which receives and stores a value F2 for the second correction of the focus offset from the controller; And a second subtractor which receives a value output from the first subtractor and subtracts the value F2 for the second correction of the focus offset and outputs the subtraction value as a value for calculating a focus servo. Offset correction device. The method of claim 5, wherein the controller determines the value F2 for the second correction of the focus offset, wherein the focus error signal FE2 is detected and input in the focus-on state for a predetermined time period. A first step of averaging to find the average value FEA2; A second step of obtaining a deviation between the average value FEA2 and the value F1 for the first order correction of the focus offset and comparing the magnitude and the value for the second order correction of the preset focus offset; As a result of comparing the second step, if the deviation is smaller than the value for the second correction of the preset focus offset, there is no signal output to the second storage unit, and the deviation is applied to the second correction of the preset focus offset. A third step of comparing the magnitude of the average value (FEA2) with a value (F1) for the first order correction of the focus offset when the value is larger than a value for the first value; If the average value FEA2 is greater than the value F1 for the first order correction of the focus offset, the third value is increased to increase the value for the second order correction of the preset focus offset, and the average value FEA2 is determined. Reducing a value for the second correction of the preset focus offset if is less than a value (F1) for the first correction of the focus offset; And if the deviation that is repeatedly calculated from the first step after performing the fourth step is smaller than a value for the second order correction of the focus offset adjusted in the fourth step, the adjusted focus offset at that time. And a fifth step of determining a value for a second order correction as a value F2 for the second order correction of the focus offset. The method of claim 6, wherein when no signal is output to the second storage unit in the third step, a signal output from the first subtractor is input to the second subtractor and used as a value for calculating a focus servo. Focus offset correction device characterized in that.

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