CN1226725C - Focus position adjustment method and system thereof - Google Patents

Abstract

The invention provides a focusing position adjusting method and a system thereof, which are used for adjusting a focusing position when an optical read-write device reads an optical storage medium. The optical storage medium has a header area and a recordable area (recording field). The optical pickup apparatus generates a focus error signal (Focus error signal), and controls the focus of an optical pickup head (pick-up head) by using the focus error signal. The method is to adjust the focus position according to the Value of the Deviation Value of the focus error signal in the header area and the recordable area after the optical pickup device is locked to track (tracking close loop) so that the Deviation Value is within a predetermined range. The system comprises an offset value detection unit for detecting the offset value and a focus control unit for adjusting the focus position.

Description

Focus position adjustment method and system thereof

technical field

The present invention relates to a focus position adjustment method and its system, in particular to a focus position adjustment method and its system applied to an optical read-write device.

Background technique

A conventional optical disc drive has an optical head for generating a laser beam to irradiate on an optical disc and receiving a laser beam reflected from the optical disc. To correctly read the data on the optical disc or to write the data into the optical disc correctly, the optical disc drive needs to perform focus servo control and tracking servo control. The focus servo is to control the laser beam emitted by the optical disc drive to the optical disc, so that the laser beam can be focused on a specific focus position. Conventional focus servo control is accomplished based on a focus error signal generated by a light beam reflected from an optical disc. The focus error signal represents the shift of the focus position (focus position) of the laser beam on the optical disc. When focusing on different positions, different jitter values can be obtained. The smaller the jitter value, the more accurate the signal obtained at the focus position is.

However, the conventional focus servo still has many problems. First, because the traditional focus servo control method is to use the focus error signal to find the maximum value of the reproduction signal (reproduction signal), or the minimum value of the jitter value (jitter), but because the two are different for different addresses or data Regions have different representation values, so errors often occur. In addition, due to the cumbersome calculation process between the focus error signal, the jitter value and the focus position, it will consume a lot of time and efficiency to obtain the minimum jitter value. Second, the traditional focus servo is applied to the unidirectional spiral magnetic track type (SS-L/G) optical disc, and it will not distinguish between the land track and the groove track, so it is impossible to distinguish the high Density discs for precise focus control. Third, the traditional focus servo does not take into account that the zero level position of the focus error signal may not be the best focus position. Errors often occur when reading data on optical discs. Regarding the shortcomings of the conventional technology, please refer to US Patent No. 6,240,055 "Focus position adjustment device and optical disc drive apparatus" (Focus position adjustment device and optical disc drive apparatus) for details.

The technology disclosed in US Patent No. 6,240,055 is used to solve the above problems. However, US Pat. No. 6,240,055 still needs to use the minimum jitter value to find the best focus position, so the speed of the focus servo cannot be effectively accelerated.

In addition, US Patent No. 6,240,055 requires an error rate counter and an RF signal detector (RF detector), and the most suitable focus position can only be obtained after calculation by a complex algorithm. Therefore, a lot of computing resources and time are wasted. Moreover, for blank optical discs, there is no so-called reproduced signal to measure the jitter value, so US Patent No. 6,240,055 cannot be applied to blank optical discs.

U.S. Patent No. 6,407,968 "Optical information recording/reproducing apparatus having focus error signal compensation" (Optical information recording/reproducing apparatus having focus error signal compensation) is to detect a deviation value and compensate the focus error signal according to this deviation value to To obtain a better focus position, the technology disclosed in US Pat. No. 6,407,968 solves the time-consuming problem of focus servo control.

When a traditional CD player reads a CD with data recorded, each time it reads a track on the CD, it will go through the seek track, track close loop and focus servo ON state in sequence. of focus servo).

Since the US Patent No. 6,407,968 detects the deviation value in the ON state offfocus servo state, the time required for the focus position adjustment is lengthened. In addition, the deviation value responds to a tracking error signal, and tracking error signal and focus error signal are required to obtain the deviation value, so the technology disclosed in US Patent No. 6,407,968 still increases the required time.

Contents of the invention

Therefore, the main purpose of the present invention is to provide a method and system for adjusting the focus position, so as to solve the problems of the conventional technology.

An object of the present invention is to provide a focus position adjustment method and system thereof, which are used to adjust a focus position when an optical read-write device reads an optical storage medium.

An object of the present invention is to provide a focus position adjustment method and system thereof, which can adjust the focus position without using a jitter value.

According to a specific embodiment of the present invention, the optical storage medium has a header area (header) and a recordable area (recording field). The optical read-write device can generate a focusing error signal, and use the signal to control the focusing condition of the optical pickup head. The method is to obtain a deviation value (DeviationValue) according to a focus signal level of the focus error signal compared with a reference level after the optical read-write device is locked (tracking close loop), and adjust the focus position so that the The deviation value is within a predetermined range. The system includes a deviation value detection unit for detecting the deviation value, and a focus control unit for adjusting the focus position.

The present invention can obtain a best focus position by controlling the deviation value. In this way, the present invention applies the original mechanism in the servo control, only adds a small number of calculation functions, and does not need to increase the hardware design, and can avoid the cumbersome calculation of the jitter value. Therefore, the present invention can save the time for the optical read-write device to find the best focus position and increase its efficiency.

The advantages and spirit of the present invention can be further understood through the following detailed description of the invention and the accompanying drawings.

Description of drawings

FIG. 1 is a schematic diagram of an optical read-write device applying the focus position adjustment system of the present invention.

2A is a graph showing the relationship between offset and jitter when reading a land-track of an optical storage medium according to an embodiment of the present invention.

FIG. 2B is a graph showing the relationship between the offset and the deviation when reading the land-track of the optical storage medium according to the embodiment of the present invention.

3A is a graph showing the relationship between offset and jitter when reading a groove-track of an optical storage medium according to an embodiment of the present invention.

FIG. 3B is a graph showing the relationship between the offset and the deviation when reading the groove-track of the optical storage medium according to the embodiment of the present invention.

FIG. 4A is a graph showing the relationship between the average offset and the jitter value when reading the optical storage medium according to an embodiment of the present invention.

FIG. 4B is a graph showing the relationship between the average offset and the deviation value when reading the optical storage medium according to the embodiment of the present invention.

FIG. 5 is a flow chart of the steps of the method for adjusting the focus position of the invention.

Label description

10: Optical reading and writing device 12: Optical storage medium

14: Optical read-write head 15: Servo control unit

16: Signal processing unit 18: Spindle motor

20: Focusing servo unit 22: Tracking servo unit

24: Focus position adjustment system 26: Deviation value detection unit

28: Focus control unit 30: Driving device

Detailed ways

See Figure 1. FIG. 1 is a schematic diagram of an optical read-write device 10 applying the focus position adjustment system of the present invention. The focusing position adjusting system of the present invention is used to adjust a focusing position when an optical read-write device 10 reads an optical storage medium 12 .

The optical read-write device 10 includes an optical read-write head 14 (optical head) and a servo control unit 15 (servo control unit). The optical storage medium 12 is rotated at a rotational speed by a spindle motor 18 , so that the optical read-write head 14 reads or writes to the optical storage medium 12 . The optical storage medium 12, especially a DVD-RAM, has a plurality of spiral recording tracks, on which at least a header area (header) and a recordable area (recording field) are used for recording digital files. Generally, when the optical read/write device 10 reads the header area and the recordable area, its focusing error signal has different levels. The focus signal level of the recordable area can be defined as a reference level, and can also represent the reference position of the optical pick-up head 14 . The difference between the focus signal level in the header area and the reference level represents the difference between the focus position and the reference position, and is defined as a deviation value.

The optical read-write head 14 is used to generate a light beam to strike the focus position on the optical storage medium 12 and receive a reflected light beam from the focus position. Whenever the optical read-write device 10 enters a track and intends to read the file data of the optical storage medium 12, it first passes through the track close loop, so that the optical read-write head 14 locks the track, and then reads the first track at the rear. mark area and recordable area.

The servo control unit 15 includes a signal processing unit 16 (signal processing unit). The signal processing unit 16 includes a focusing servo unit 20 and a tracking servo unit 22 . The focus servo unit 20 is used for analyzing the reflected light beam received by the optical pick-up head 14 and generating the focus error signal.

The servo control unit 15 further includes a focus position adjustment system 24 of the present invention. The focus adjustment system 24 includes a deviation detection unit 26 and a focus control unit 28 . The deviation value detection unit 26 is used to measure the deviation value (Deviation Value) between the focus error signal in the header area and the reference level after the optical read-write device 10 is locked to the track (tracking close loop). The focus control unit 28 is used to adjust the focus position so that the deviation value is within a predetermined range.

The deviation detection unit 26 compares a signal level of the focus error signal with a reference level to determine the deviation. The reference level is a level generated when the reflected light beam is reflected from the reference position. The deviation value can be obtained according to a comparison value between the signal level and the reference level. The deviation value detection unit 26 detects and judges the signal level and the reference level to obtain the variation of the voltage therein, and further obtains the deviation value between the focus position and the reference position. The focus control unit 28 generates a focus control signal according to a difference between the deviation value and a predetermined range for adjusting the focus position so that the deviation value is within the predetermined range.

The focus adjustment system 24 further includes a driving device 30 for adjusting the focus position of the optical pickup 14 according to the focus control signal generated by the focus control unit 28 .

For DVD-RAM, due to the different structures of the header area and the recordable area, the focus error signal of the optical read-write head 14 in the header area and the recordable area will be different. The writing device 10 can apply an offset to the optical pickup 14 to adjust the focus position of the optical pickup 14 .

The optical read-write device 10 generates a jitter value when reading the optical storage medium 12 . When the jitter value is smaller, it means that the optical read-write device 10 has a better focus position. There is a corresponding relationship between the jitter value and the forced offset, and the jitter value will change with the variation of the offset. When the offset is within a range, it will have a better jitter value.

There is a corresponding relationship between the offset (offset) and the deviation value (Deviation Value). By adjusting the deviation value below the specific range, the deviation value can be within the range.

Please refer to Figures 2A-B, 3A-B and 4A-B. 2A is a graph showing the relationship between offset and jitter when reading a land-track of an optical storage medium according to an embodiment of the present invention. FIG. 2B is a graph showing the relationship between the offset and the deviation when reading the land-track of the optical storage medium according to the embodiment of the present invention. 3A is a graph showing the relationship between offset and jitter when reading a groove-track of an optical storage medium according to an embodiment of the present invention. FIG. 3B is a graph showing the relationship between the offset and the deviation when reading the groove-track of the optical storage medium according to the embodiment of the present invention. FIG. 4A is a graph showing the relationship between the average offset and the jitter value when reading the optical storage medium according to an embodiment of the present invention. FIG. 4B is a graph showing the relationship between the average offset and the deviation value when reading the optical storage medium according to the embodiment of the present invention.

As shown in FIG. 2A , when reading the land-track of the optical storage medium 12 , when the offset is 0 mV, the jitter value is not the minimum value. When the offset is adjusted between 120mV and 300mV, the corresponding minimum jitter value is about 2%. Therefore, when the offset is controlled between 120 mV and 300 mV when reading the platform track of the optical storage medium 12 , the minimum jitter value can be obtained. Corresponding to FIG. 2B , as long as the deviation value is controlled below 100 mV, the best focus position of the optical pickup head can be obtained.

As shown in FIG. 3A , when reading the groove-track of the optical storage medium 12 , when the offset is between 0 mV and 300 mV, the corresponding minimum jitter value is about 2%. Offsets are tolerable between -100mV and 300mV. See Figure 3B. When reading the groove track of the optical storage medium 12, as long as the deviation value is set below 100 mV, the optimum jitter value can be obtained.

As shown in FIG. 4A , when the average offset is between about 120 mV and 300 mV, the jitter value is in a tolerable range. According to an embodiment of the present invention, when the optical read-write device reads the optical storage medium 12 , please refer to FIG. 4B . When reading the groove track of the optical storage medium 12 , as long as the average deviation value is set below 100 mV, a best focus position for reading the optical storage medium 12 can be obtained.

Compared with the traditional technology, the present invention applies the original mechanism in servo control, only adds a small number of calculation functions, and does not need to increase hardware design, so as to avoid cumbersome calculation of jitter values. As long as the deviation is controlled within an appropriate interval, the best focus position for the optical head 14 to read the optical storage medium 12 can be obtained. It not only improves many problems of the traditional technology, but also saves a lot of time for the optical reading head 14 to find the best focus point, and increases the performance of the optical reading and writing device 10 .

Please refer to FIG. 5 . FIG. 5 is a flow chart of the steps of the method for adjusting the focus position of the present invention. The focus position adjustment method of the present invention comprises the following steps:

Step S30: start;

Step S32: After the optical read-write device 10 is locked, read the focus error signal in the header area;

Step S34: judging the deviation value between the focus position and the reference position according to the focus signal level of the focus error signal;

Step S36: detecting the deviation value;

Step S38: Generate a focus control signal according to the difference between the deviation value and the predetermined range;

Step S40: adjusting the focus position according to the focus control signal so that the deviation value is within a predetermined range;

Step S42: Finish.

The invention provides a focusing position adjustment method and system thereof, which are used for adjusting a focus position when an optical read-write device reads an optical storage medium. The method is to adjust the focus position according to the deviation value (Deviation Value) between a focus signal level and a reference level of the focus error signal in the header area after the optical read-write device is locked to the track (tracking close loop), so that the deviation value is within a predetermined range. The system includes a deviation value detection unit for detecting the deviation value, and a focus control unit for adjusting the focus position. The present invention can obtain the best focus position by controlling the deviation value. In this way, the present invention applies the original mechanism in the servo control, only adds a small number of calculation functions, and does not need to increase the hardware design, so as to avoid the cumbersome calculation of the jitter value. Therefore, the present invention saves a lot of focusing time of the optical pickup head and increases the performance of the optical read-write device.

With the above detailed description of the preferred embodiments, it is hoped that the features and spirit of the present invention can be described more clearly, and the scope of the present invention is not limited by the preferred embodiments disclosed above. On the contrary, the intention is to cover various modifications and equivalent arrangements to the invention.

Claims (13)

1. A focus position adjustment system, used to adjust a focus position when an optical read-write device reads an optical storage medium, the optical storage medium has a header area and a recordable area, the optical read-write The position where the device successfully focuses on the recordable area is defined as a reference position, and the signal obtained at this position is a reference signal. When the optical read-write device reads the header area, a focus error signal is obtained. The system includes: a deviation detection unit, used to determine a deviation value between the focus position and the reference position according to the focus error signal in the header area after the optical read-write device is locked; and A focus control unit is used to adjust the focus position so that the deviation value is within a predetermined range. 2. The system according to claim 1, wherein the deviation value detection unit uses a focus signal level of the focus error signal to compare with a reference level, the focus signal level indicates the focus position, the reference level The level is a level generated when the reflected light beam is reflected from the reference position, and a comparison value between the focusing signal level and the reference level can obtain the deviation value. 3. The system of claim 2, wherein the optical read/write device further comprises: an optical read/write head for generating a beam of light that strikes the focus position on the optical storage medium, and receives a reflected beam from the focus position; and A signal processing unit is used for analyzing the reflected light beam received by the optical pick-up head, and generating the focusing error signal. 4. The system according to claim 3, wherein the optical read-write device applies an offset to the optical read-write head to adjust the focus position, and there is a corresponding relationship between the offset and the offset value , by adjusting the deviation value within the predetermined range, the offset can be within the interval. 5. The system as claimed in claim 4, wherein the focus control unit generates a focus control signal according to a difference between the deviation value and the predetermined range. 6. The system as claimed in claim 5, further comprising a driving device for adjusting the focus position of the optical pickup according to the focus control signal. 7. The system of claim 1, the optical storage medium is a DVD-RAM. 8. A focus position adjustment method, used to adjust a focus position when an optical read-write device reads an optical storage medium, the optical storage medium has a header area and a recordable area, the optical read-write The position where the device successfully focuses on the recordable area is defined as a reference position, and the signal obtained at this position is a reference signal. When the optical read-write device reads the header area, a focus error signal will be obtained. The method includes: After the optical read-write device is track-locked, judge the value of a deviation between the focus position and the reference position according to the focus error signal in the header area; and The focus position is adjusted so that the deviation value is within a predetermined range. 9. The method as claimed in claim 8, wherein a focus signal level of the focus error signal is compared with a reference level, the focus signal level indicates the focus position, and the reference level is when the reflected light beam The deviation value is a comparison value between the focus signal level and the reference level generated when the level is reflected from the reference position. 10. The method of claim 9, wherein the optical read-write device further comprises: an optical read/write head for generating a beam of light that strikes the focus position on the optical storage medium, and receives a reflected beam from the focus position; and A signal processing unit is used for analyzing the reflected light beam received by the optical pick-up head, and generating the focusing error signal. 11. The method according to claim 10, wherein the optical read-write device applies an offset to the optical read-write head to adjust the focus position, and there is a corresponding relationship between the offset and the offset value , by adjusting the deviation value within the specific range, the offset can be within the interval. 12. The method of claim 11, further comprising the steps of: A focus control signal is generated according to the difference between the deviation value and the predetermined range. 13. The method of claim 12, further comprising the steps of: The focus position is adjusted according to the focus control signal.

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