KR20020067321A - System for controlling servo capable of adjusting offset by data reproduction (recording) area and method for offset adjusting using the same - Google Patents

Abstract

PURPOSE: A servo control system enabling offset adjustment for data playback or recording areas and an offset adjusting method using the same are provided to designate offsets for data recording or playback areas configuring an optical disk, so as to maintain an optimum focusing or tracking state in any recording or playback area. CONSTITUTION: An optical disk servo control system includes focusing and tracking error amplifying units(44,46), and drives an actuator(54) to minimize errors of played signals. The focusing and tracking error amplifying units include offset adjusting units(44c,46c) adjusting offsets in a direction minimizing the errors of the played signals, and offset selection units. In the offset selection units, land offsets generators(44d,46d) generate offsets for offset adjustment in land areas of the optical disk. Groove offsets generators(44e,46e) generate offsets for offset adjustment in groove areas of the optical disk. And multiplexers(44f,46f) select one of offsets generated in the land and groove offsets generators, for outputting to the offset adjusting units.

Description

System for controlling servo capable of adjusting offset by data reproduction (recording) area and method for offset adjusting using the same}

The present invention relates to a servo control system and an offset adjustment method for offset adjustment when detecting a focus and track signal in an optical disk, and in detail, a servo control system capable of selectively adjusting offset according to a land / groove area and an offset using the same. It is about an adjustment method.

Optical discs, such as a compact disc (CD) or a digital versatile disc, have land and groove areas as data reproduction (recording) areas.

In the ideal case where the tracking error of the optical disc does not occur when recording or reproducing the recorded information on the optical disc, since the land and groove areas are each located at different distances from the objective lens, When recording (reproducing) data into the groove (land) area, a focusing error occurs due to a change in focal length. Therefore, an offset adjustment is necessary to correct this.

1 is an optical disk servo control system currently widely used for offset adjustment of an optical disk, and includes a quadrant photodiode that receives an optical signal for error detection of an optical disk and outputs a current signal corresponding to the received signal. A), and the current (I) / voltage (V) amplifier (B) for converting the signal output from the four-segment photodiode (A) into a voltage and the output voltage of the current / voltage amplifier (B) The detected error is calculated according to the offset adjustment signal output from the focusing (tracking) error amplifier C and the focusing (tracking) error amplifier C in which a calculation is performed, amplification of the calculation result signal, and appropriate offset adjustment is performed. It is composed of a servo processor (E) for driving an actuator (F) so as to minimize.

The servo control system having such a configuration will be described by taking DVD-RAM disks (hereinafter, referred to as disks) as an example.

Specifically, the optical signal reproduced in the groove area of the disc is subjected to the appropriate calculation, signal amplification, and optimum in the focusing (tracking) error amplifier C through the four-segment photodiode A and the current / voltage amplifier B. The offset is adjusted to be in a focusing (tracking) state, and the offset state thus adjusted remains thereafter. Therefore, the focusing (tracking) of the groove area is optimal, while the focusing (tracking) of the land area is not optimal. In the opposite case, the focusing (tracking) of the land area is optimal, while the focusing (tracking) of the groove area is not optimal. In addition, when the offset is adjusted to the average value of the groove area and the land area, the focusing (tracking) does not become the worst state in any of the areas, but it is not the optimal state.

As such, the optical disc servo control system currently used uses the adjusted offset value as an offset value for other unselected areas in order to minimize errors detected in any one of the groove area and the land area of the optical disc. Alternatively, since the offset value corresponding to the average of the land area and the groove area is used as the offset value for each area, the focusing (tracking) state of one area can be kept optimal, while the focusing (tracking) of the other area is maintained. ) May not be optimal, or may not be optimal in both land and groove areas.

Therefore, the technical problem to be solved by the present invention is to improve the above-mentioned problems of the prior art, and to specify an offset for each data recording (reproducing) area constituting the optical disc, thereby providing optimal focusing (tracking) in any recording (reproducing) area. An optical disk servo control system capable of maintaining the state is provided.

Another object of the present invention is to provide an offset adjustment method using the servo control system.

1 is a configuration diagram of a servo control system according to the prior art.

2 is a configuration diagram of a servo control system according to an embodiment of the present invention.

3 is a detailed circuit diagram illustrating a focusing or tracking error amplifier of FIG. 2.

* Description of Signs of Major Parts of Drawings *

40: light receiver 42: current / voltage amplifier

44, 46: focusing and tracking error amplifier

48: servo processor

50, 52: Offset selector 54: Actuator

44d, 46d: Land offset generator 44e, 46e: Groove offset generator

44f, 46f: multiplexer

In order to achieve the above technical problem, the present invention provides a light receiving unit for receiving and photoelectric conversion of the optical signal input from the optical disk, a current / voltage amplifier for converting the output current of the light receiving unit into a voltage, and the current / voltage amplifier A focusing (tracking) error amplifier configured to adjust an offset in a direction of minimizing the detected error signal through detection and amplification of a focusing (tracking) error signal from an output voltage, and the input from the focusing (tracking) error amplifier In a servo control system of an optical disc having a servo processor for driving an actuator to minimize the detected error based on an offset adjustment signal, the focusing (tracking) error amplifier unit adjusts the offset in a direction to minimize the detected error. Connected to the offset adjustment unit and connected to the external control signal And an offset selection unit for selecting an offset for each data reproduction (recording) area of the optical disc and providing it as an input signal of the offset adjustment unit.

The offset selection unit may include a land offset generator for generating an offset for offset adjustment of a land area of the optical disc, a groove offset generator for generating an offset for offset adjustment of a groove area of the optical disc, and the control. And a multiplexer for selecting one of the offsets generated by the land and groove offset generator according to the signal and outputting the selected one to the offset adjuster.

In order to achieve the above technical problem, in the offset adjustment method for the focusing (tracking) error of the optical disk having a land and groove area, in the offset and groove area for the focusing (tracking) error generated in the land area Offsets for generated focusing (tracking) errors are adjusted using different offset values. In this case, the offset for the focusing (tracking) error generated in the land and groove areas is adjusted based on the offset generated in the land and groove area offset generators, respectively.

According to the present invention, since the offset can be adjusted for each land area or groove area of the optical disc, an optimal focusing (tracking) state can be maintained for each area.

Hereinafter, a servo control system capable of selectively adjusting offset according to an area according to an embodiment of the present invention and an offset adjusting method using the same will be described in detail with reference to the accompanying drawings. In the process, the regions shown in the drawings are symbolic ones representing actual components, and the regions are exaggerated for clarity of specification.

Referring to FIG. 2, reference numeral 40 denotes a light receiving unit for receiving an optical signal input from an optical disk having a land and groove area, and 42 denotes a current / voltage amplifier for converting a current output from the light receiving unit 40 into a voltage. Indicates. Although the light receiving unit 40 exemplifies a four-divided photodiode as a photodiode, other multi-divided photodiodes such as a six-divided photodiode and the like may also be used. In this way, when the dividing surface of the photodiode is changed, the number of amplifiers constituting the current / voltage amplifier 42 is also changed.

Subsequently, reference numeral 44 detects a focusing error signal of the optical disk from the output voltage of the current / voltage amplifier 42, amplifies the detected signal, and offsets the detected error signal in the direction of minimizing the focusing error. Is a focusing error amplifier for adjusting the offset, and 46 indicates a tracking error amplifier for adjusting the offset in the direction of detecting, amplifying and minimizing the tracking error signal of the optical disk from the output voltage of the current / voltage amplifier 42. Each of the error amplifiers 44 and 46 respectively includes subtractors 44a and 46a for detecting an error from an output voltage of the current / voltage amplifier 42 and amplifiers 44b and 46b for amplifying a signal output therefrom. Offset adjusting units 44c and 46c for adjusting the offset in the direction of minimizing the amplified error signal are provided. The offset adjusters 44c and 46c include the land offset generators 44d and 46d for generating the offset signal of the land area, the groove offset generators 44e and 46e for generating the offset signal of the groove area, and an external control signal. Offset selectors 50 and 52 composed of multiplexers 44f and 46f for selecting any one of the offsets generated by the land offset generators 44d and 46d and the groove offset generators 44e and 46e by It is connected. The external control signal is 0 or 1 indicating this fact when the reproduction (recording) area of the optical disc changes from the land (groove) area to the groove (land) area.

Reference numeral 48 denotes a servo processor, which drives the actuator 54 in a direction to minimize the detected error by using the offset adjustment signals output from the offset adjustment units 44c and 46c as input signals.

Meanwhile, referring to FIG. 3, one of the offset signals selected by the multiplexer 44f of the offset selector 50, that is, the output signal of the multiplexer 44f may be compared with the output signal of the focusing (tracking) error amplifier 44b. Together, the input signal of the offset adjustment part 44c is comprised. The offset adjusting unit 44c compares the input signals and adjusts an offset for each land area or groove area, and the offset adjustment signal thus adjusted becomes an input signal of the servo processor 48.

The following describes a focusing and tracking offset adjustment method using the servo control system according to the present invention shown in FIG.

Referring to FIG. 2, when an optical signal including a focusing or tracking error is input to the light receiving unit 40 from a land area of the optical disc, an output current corresponding to the optical signal is generated at the light receiving unit 40 by photoelectric conversion. . The current generated by the light receiver 40 is converted into a voltage while passing through the current / voltage amplifier 42 and input to the focusing (tracking) error amplifier 44. The voltage input from the current / voltage amplifier 42 is input to the subtractor 44a of the focusing error tracking unit 44, and the subtractor 44a detects a focusing (tracking) error signal. The error signal detected by the subtractor 44a is amplified by the amplifiers 44b and 46b and input to the offset adjusters 44c and 46c. The offset adjusters 44c and 46c compare the signals input from the multiplexers 44f and 46f of the offset selectors 50 and 52 together with the signals input from the amplifiers 44b and 46b to compare the detected error signals. The offset is adjusted in a direction that can be minimized, and the result is output to the server processor 48 as an offset adjustment signal. The server processor 48 drives the actuator 54 based on the offset adjustment signals input from the offset adjustment units 44c and 46c so that the detected error signal is minimized, so that a focusing (tracking) error is minimized.

On the other hand, when the data reproduction (recording) area of the optical disc is changed from the land area to the groove area, this fact is input to the multiplexers 44f and 46f of the offset selectors 50 and 52 as a control signal, and the multiplexer ( Instead of selecting land offset signals generated by the land offset generators 44d and 46d, 44f and 46f select the groove offset signals generated by the groove offset generators 44e and 46e to offset the controllers 44c and 46c. The offset adjusters 44c and 46c compare the signals input from the amplifiers 44b and 46b with the groove offset signals and output an offset adjustment signal in a direction to minimize the detected error signal. Based on this, the servo processor 48 drives the actuator to minimize the focusing (tracking) error in the groove area.

In this way, even when the data recording area of the optical disc is changed from the land (groove) area to the groove (land) area, the optimum focusing (tracking) state can be maintained at all times.

While many details are set forth in the foregoing description, they should be construed as illustrative of preferred embodiments, rather than to limit the scope of the invention. For example, one of ordinary skill in the art may include an offset selection unit in which a multiplexer is replaced with another signal selection unit, and groove offset generation units 44e and 46e and land offset generation unit 44d are provided. , May be provided with an offset generating unit integrating 46d) into one. Therefore, the scope of the present invention should not be defined by the described embodiments, but should be determined by the technical spirit described in the claims.

As described above, the optical disc servo control system of the present invention has a focusing (tracking) error amplifying section, which is connected to it with an offset adjusting section, and has an offset selecting section for selecting a land offset or groove offset according to the data reproduction (recording) area. do. Therefore, even if the data reproduction (recording) area is changed from the land (groove) area to the groove (land) area, the offset can be adjusted so as to optimize the focusing (tracking) state in each changed area. Tracking) state.

Claims (8)

An optical disc servo control system having a focusing (tracking) error amplifier for adjusting an offset in a direction of minimizing an error of a reproduced signal and driving an actuator to minimize an error of the reproduced signal, The focusing (tracking) error amplifier includes an offset adjuster for adjusting an offset in a direction to minimize the error; And And an offset selecting section for selecting an offset for each data reproduction (recording) area of the optical disk by an external control signal and providing the offset signal as an input signal of the offset adjusting section. The method of claim 1, The offset selector may include a land offset generator configured to generate an offset for adjusting an offset of a land area of the optical disc; A groove offset generator for generating an offset for adjusting an offset of the groove area of the optical disk; And And a multiplexer for selecting any one of the offsets generated by the land and groove offset generator according to the control signal and outputting the selected one to the offset adjuster. In the offset adjustment method for the focusing error of an optical disk having a land and groove area, And an offset for focusing error generated in the land area and an offset for focusing error generated in a groove area, respectively. The method of claim 3, wherein The offset for the focusing error generated in the land area is adjusted based on the offset generated in the land area offset generator. The method of claim 3, wherein The offset for the focusing error generated in the groove area is adjusted based on the offset generated in the groove area offset generator. In the offset adjustment method for the tracking error of the optical disk having land and groove area, And an offset for the tracking error generated in the land area and an offset for the tracking error generated in the groove area. The method of claim 6, The offset for the tracking error generated in the land area is adjusted based on the offset generated in the land area offset generator. The method of claim 6, The offset for the tracking error generated in the groove area is adjusted based on the offset generated in the groove area offset generator.