U. S. Patent No. 5,121,373 (granted to Mark A. Barton et al.) entitled "TRACK JUMPING METHOD FOR AN OPTICAL DISK READING HEAD" discloses a method for automatically compensating a position error which happens in a present jump.

However, according to the above mentioned track jump method, the optical pick-up unit can not jump to an actual target jump position since an over-jump or an under-jump can arise. Furthermore, despite the completion of the jump operation, a whole system of the optical disc player may enter into an unstable state due to an instantaneous oscillation or wavings of the optical pick-up unit even. Consequently, it will take a long time to initiate a normal reproduction from the track jump of the optical pick-up unit. Additionally, since the optical disc player performs the track jump without considering the characteristics of each optical disc, an accurate track search becomes no more possible.

Disclosure of Invention It is a first object of the present invention to provide a method for controlling a track search of an optical disc which can decrease a track search time of the optical disc system and reduce a track search error thereof.

It is a second object of the present invention to provide an apparatus for controlling the track search of the optical disc which can decrease the track search time of the optical disc system and reduce the track search error thereof.

In order to achieve the second object, two methods and two apparatuses of this invention are provided.

A first method for controlling a track search of an optical disc, which comprises the steps of: (i) reading out acceleration data about the optical disc which is currently loaded for reproducing programs recorded on the optical disc from a storage of acceleration information; (ii) implementing a track jump for an optical beam to enter into an area of a target track based on the first acceleration information; (iii) comparing a first signal which represents the target track position with a second signal which represents a current jumping track position for finding an

error in the track jump; (iv) updating the acceleration information in the storage with new acceleration information of the optical disc which has been compensated by the error to reduce errors in the track jump upon a next reproduction for the optical disc, based on said comparison; and (v) implementing an accurate search for the target track after the track jump by using the first signal and the error.

The present invention provides a second method for controlling a track search of an optical disc, which comprises the steps of: (a) reproducing said optical disc in a normal mode by using a first servo gain and a first servo off-set value which are stored in a data storage as servo control factors; (b) calculating a track jump distance between a current track and a target track which is pointed by a user's selection; (c) reading out a second servo gain and a second servo off-set value which corresponds to said track jump distance from said data storage; (d) implementing a track jump of an optical pick-up unit toward the target track of the optical disc; (e) implementing a servo control of the optical disc by using said second servo gain and said second servo off-set value based on an inspection as to the question of whether a jumping position of said optical pick-up unit is within an error limit from said target track; and (f) implementing the servo control of the optical disc by using said first servo gain and said servo off-set value when a time for said servo control in said step (e) reaches a preset time.

The present invention provides a first apparatus for controlling a track search of an optical disc, which comprises: an optical pick-up unit for reading out data from said optical disc and outputting a data signal; a reproducing means for processing the data signal into a digital signal, and for outputting a reproduction position signal which represents a current reproduction position of said optical pick-up unit; a focusing servo means for implementing a focusing servo of said optical pick-up unit; a tracking servo means for implementing a tracking servo of said optical pick-up unit; a transferring servo means for transferring said optical pick-up unit; a storing means for holding a servo gain and a servo off-set value corresponding to a track jump distance of said optical disc; a control means for reading out a first servo gain and a first servo off-set value from said storing means, for controlling said focusing servo means and said tracking servo means to implement a servo control of said optical disc according to the first servo gain and the first servo off-set value, for receiving the

reproduction position signal from said reproducing means, for calculating the track jump distance between the present reproduction track and the target track of said optical pick-up unit according to the track jump signal inputted by the user's key selection, for reading out a second servo gain and a second servo off-set value corresponding to the calculated track jump distance from said storing means, for controlling said transferring servo means to make said optical pick-up unit jump to the target track based on the second servo gain and the second servo off-set value, for controlling said focusing servo means and said tracking servo means to implement the servo control of the optical disc according to the second servo gain and the second servo off-set value during a preset time, and for controlling said focusing servo means and said tracking servo means to implement the servo control of the optical disc according to the first servo gain and the first servo off-set value when the preset time has elapsed.

The present invention provides a second apparatus for controlling a track search of an optical disc, which comprises: an optical pick-up unit for irradiating an optical beam onto the optical disc and for converting a reflected optical beam from the optical disc into an electric signal to output the electric signal; a tracking error signal generating means for outputting a tracking error signal which represents whether or not the optical beam hits accurately on a track center of the optical disc based on the electric signal from said optical pick-up unit; an inverting/non-inverting means for inverting or non-inverting the tracking error signal from said tracking error signal generating means; a peak holding means for holding a peak value of the tracking error signal from said inverting/non-inverting means to output a peak value signal of the tracking error signal; a reference level signal generating means for outputting a reference level signal corresponding to the peak value signal from said peak holding means; a first comparing means for comparing the level of the tracking error signal from said inverting/non-inverting means with the reference level signal from said reference level signal generating means to generate a first clock signal whenever the level of the tracking error signal becomes equal to the level of the reference level signal; a jump status detecting means for comparing the tracking error signal from said inverting/non-inverting means with a predetermined comparing level signal to output track jump status signal which represents track jump status; a driving

means for applying a driving signal to said optical pick-up unit for a track jump of said optical pick-up unit; a jump signal generating means for applying a jump signal to said driving means for operating said driving means, and for supplying a jump completion signal to said jump status detecting means when the track jump of said optical pick-up unit finishes; a storing means for storing a reference acceleration time and a reference deceleration time which represent the ratio of the peak value of the tracking error signal to the level of the reference level signal; and a control means, responsive to the track jump status signal from said jump status detecting means, the first clock signal from said first comparing means, and a standard value signal from said storing means, for controlling said jump signal generating means to control the track jump of said optical pick-up unit.

In the method and the apparatus for controlling a track search of an optical disc according to the present invention, the optical disc system can reduce a jump error such as an over-jump and an under-jump of the optical pick-up unit and suppress the occurrence of an unstable reproduction due to an instantaneous shaking of the optical pick-up unit. Also, after the track jump operation of the optical pick-up unit, the optical disc system can reduce a delay time to initiate a normal reproduction of the optical disc. As a result of it, the optical disc system can execute the track search accurately and with stable.

Brief Description of the Drawings The above objects and other advantage of the present invention will become more apparent by describing in detail a preferred embodiment thereof with reference to the attached drawings, in which: FIG. 1 is a schematic section view showing a track jump position of an optical pick-up unit on an optical disc; FIG. 2 is a block diagram showing a circuit configuration of an apparatus for controlling a track search in an optical disc system according to a first embodiment of the present invention; FIG. 3 is a flowchart illustrating a method for controlling a track search of an optical disc system using the apparatus shown in FIG. 2; FIG. 4 is a block diagram showing a circuit configuration of an apparatus for

controlling a track search in an optical disc system according to a second embodiment of the present invention; FIG. 5 is a flowchart illustrating a method for controlling a track search of an optical disc system using the apparatus shown in FIG. 4; and FIG. 6 is a block diagram for showing a circuit configuration of an apparatus for controlling a track search in an optical disc system according to a third embodiment of the present invention.

Best Mode for Carrying Out the Invention A description will be given below in detail with reference to accompanying drawings to a configuration and an operation of an apparatus and a method for controlling a track search of an optical disc system according to the embodiments of the present invention.

Embodiment 1 As shown in FIG. 2, according to a first embodiment of the present invention, the apparatus for controlling a track search of an optical disc system has a key inputting section 10 for generating a key signal corresponding to a key operation by a user, a system control section 20 for controlling an operation of the optical disc system in response to the key signal from the key inputting section 10 and to signals from the members of an optical disc reproducing section 40, and a storing section 30 for storing acceleration information corresponding to an inter-track distance of the optical disc, an identification number of the optical disc, and updated acceleration information corresponding to the identification number. The optical disc reproducing section 40 has an optical pick-up unit 41 for irradiating a laser beam onto the optical disc and for transforming the reflected beam from the optical disc into an electric signal to output, a tracking error signal detecting section 42 for detecting and outputting a tracking error signal which represents as to whether the laser beam accurately hits on the center track of the optical disc based on the electric signal from the optical pick-up unit 41, a tracking servo control section 43 for controlling the laser beam to accurately trace along the track of the optical disc, a motor driving section 44 for outputting an optical pick-up transferring signal in response to a control signal from the system control section 20, and an optical pick-up transferring motor

45 for conveying the optical pick-up section 41, in response to the optical pick-up transferring signal from motor driving section 44.

If a search key signal from the key inputting section 10 is provided for the system control section 20 during the operation of the optical disc reproducing section 40, the system control section 20 interrupts the operation of the optical disc reproducing section 40. When a target track position signal which represents a target track is provided by the user's operation from the key inputting section 10, the system control section 20 reads out the acceleration information corresponding to the identifying number of the optical disc D from the storing section 30, and controls a motor driving section 44 and an optical pick-up transferring motor 45 to convey the optical pick-up section 41 to the target track based on the accelerated velocity information that was read out.

The system control section 20 monitors a track jump position of the optical pick-up section 41 in response to the tracking error signal from the tracking error signal detecting section 42, detects a distance error between the actual-jumping position and the target track position of the optical pick-up section 41, and updates acceleration information based on the distance error.

The updated acceleration information is stored with the identifying number of the optical disc D in the storing section 30.

FIG. 3 is a flowchart illustrating a method for controlling a track search of an optical disc by using the apparatus shown in FIG. 2. As described in FIG. 3, after the optical disc D has been loaded (step S100), the optical disc reproducing section 40 reads out a table-of-contents (TOC) information about the TOC area, which is located in the load-in area of the optical disc D, to provide the TOC information for the system control section 20. The system control section 20 stores the TOC information in a memory field (not shown) in the system control section 20, or in the storing section 30 (step S102). Here, the TOC information includes position information of each track and the identifying number of the optical disc D. The identifying number of the optical disk D is an absolute time of the optical disc which is read out from the TOC information of the optical disc D.

In step S104, when the search key signal is provided by the user's operation from the key inputting section 10 during a reproduction mode of the optical disc D

(step S106), the system control section 20 changes the operation mode into a stand-by mode for the user to set a target jump position. When the user's operation supplies a target jump position signal arising from the key inputting section 10 (step S108), the system control section 20 starts to search for the question of whether there is the updated acceleration information corresponding to the identifying number of the loaded optical disc D in the storing section 30 (step S110).

In step S110, if the updated acceleration information does not exist, the system control section 20 reads out predetermined standard acceleration information (step S112). When the updated acceleration information, however, exists in the storing section in step S110, the system control section 20 reads out this updated acceleration information corresponding to the loaded optical disc D (step S114). The system control section 20 controls the motor driving section 44 and the optical pick-up transferring motor 45 to move the optical pick-up section 41 toward the target track position Tp'taht is adjacent to the target jump position Tp (step S116), based on either standard acceleration information or the updated acceleration information.

Here, the target track position Tp', which is the track position closest to the target jump position Tp, can be obtained from the TOC information which is read out in step S102.

In step S118, the system control section 20 detects out a current jumping position Tjl of the optical pick-up section 41 and compares the current jumping position Tjl with the target track position Tp'. If the position Tjl is equal to the target track position Tp', the system control section 20 has the absolute time of optical disc D read out in step S102 and the acceleration information used in step S116 to be saved in the storing section 30 (step S122). However, if the current jumping position Tj 1 is not equal to the target track position Tp', the system control <BR> <BR> <BR> section 20 calculates a distance error A t between the current jumping position Tj 1 and the target track position Tp', and compensates the acceleration information used in step S116 as many as the distance error At. The system control section 20 has the updated acceleration information, together with the identifying number of the optical disc D, to be saved in the storing section 30 (step S122).

When an object lens of the optical pick-up section 41 becomes stable, the system control section 20 makes the object lens move to the target jump position Tp

from the current jumping position Tj 1 and performs the control of the tracking servo control section 43. The optical pick-up section 41 carries out an accurate search for the target jump position Tp under the control of the servo control section 43 by using the signal of the target track and the error in the track jump (step S124).

Embodiment 2 As shown in FIG. 4, according to a second embodiment of the present invention, the apparatus for controlling the track search of the optical disc system has an optical pick-up unit 200, a focusing servo section 202, a tracking servo section 204, a transferring servo section 206, a reproducing section 208, a control section 210, and a storing section 212.

As a data signal, the optical pick-up unit 200 reads out program data from the optical disc D to output. The focusing servo section 202 conducts the focusing servo control of the optical pick-up unit 200 based on a focusing gain and a focusing off- set. The tracking servo section 204 conducts the tracking servo control of the optical pick-up unit 200 based on a tracking gain and a tracking off-set value. The transferring servo section 206 handles the movement of the optical pick-up unit 200.

The reproducing section 208 reproduces the data signal as a digital signal, and also outputs a reproducing position signal which represents a current reproducing position of the optical pick-up unit 200. The storing section 212 stores the servo gain and the servo off-set corresponding to inter-track distance of the optical disc D. The control section 210 fetches out the first servo gain and the first servo off-set from the storing section 212, and controls the focusing servo section 202 and the tracking servo section 204 to execute a servo control of the optical disc D according to the first servo gain and the first servo off-set. Furthermore, the control section 210, responsive to the reproducing position signal arising from the reproducing section 208 and the track jump signal generated by a user's operation, calculates a track jumping distance of the optical pick-up unit 200 from a currently reproducing track to a target track, and reads out a second servo gain and a second servo off-set which are correspondences to the calculated track jump distance from the storing section 212.

The control section 210 controls the transferring servo section 206 to make the optical pick-up unit 200 jump over the target track based on the second servo gain and the second servo off-set value. The control section 210 controls the focusing servo section

202 and the tracking servo section 204 for the servo control of the optical disc D by using the second servo gain and the second servo off-set during a predetermined time.

On the other hand, after the predetermined time, the control section 210 uses the first servo gain and the first servo off-set for controlling the focusing servo section 202 and the tracking servo section 204.

FIG. 5 is a flowchart describing a method for controlling a track search of an optical disc by using the apparatus shown in FIG. 4. As shown in FIG. 5, after the optical disc D is loaded, the control section 210 reads out the first servo gain and the first servo off-set from the storing section 212, and the focusing servo section 202 and tracking servo section 204 implement the reproduction mode of the optical disc D with the first servo gain and the first servo off-set (step S300).

In step S302, when the track jump signal is provided by the key inputting section 10 activated by the user's operation, the control section 210 calculates a distance between a current reproducing track and a target track which are the correspondences of the reproduction position signal from the reproducing section 208 and the track jump signal respectively (step S304).

The control section 210 reads out the second servo gain and the second servo off-set, which are the correspondences of the distance which is previously calculated in step S304, from the storing section 212 (step S306). The control section 210 makes the optical pick-up unit 200 perform a track jump based on the calculated distance first (step S308). When the optical pick-up unit 200 reaches the target track (step S310), the control section 210 controls the transferring servo section 206 to quit the track jump of the optical pick-up unit 200. Next, the focusing servo section 202 and the tracking servo section 204, under the control of the control section 210, implement the focusing servo of and the tracking servo of the optical pick-up unit 200 with the second servo gain and the second servo off-set.

Meanwhile, when the focusing servo section 202 and the tracking servo section 204 enter into the state of normal operation, the optical pick-up unit 200 becomes capable of reading out the program data normally from optical disc D, and, for the program reproduction of the optical disc D, provides the reproducing section 208 with the data that was read out.

If the time for program reproduction T with the second servo gain and the

second off-set reaches to a predetermined time tl (step S314), the control section 210 controls the focusing servo section 202 and the tracking servo section 204 to perform their servo operations with the first servo gain and the first servo off-set.

Embodiment 3 In FIG. 6, according to a third embodiment of the present invention, the apparatus for controlling a track search of the optical disc system has an optical pick- up unit 400, a tracking error signal generating section 410, a phase compensating section 420, an inverting/non-inverting section 430, a peak holding section 440, a reference level signal generating section 450, a first comparing section 460, a jump signal generating section 470, a switching section 480, a control section 490, a driving section 500, a jump status detecting section 510, and a storing section 520.

The optical pick-up unit 400 irradiates a laser beam onto the optical disc D and converts an reflected beam from the optical disc D into an electric signal to output.

The tracking error signal generating section 410 produces a tracking error signal which indicates whether or not the laser beam accurately hits on the center track of the optical disc D based on the electric signal from the optical pick-up unit 400. In the event that the optical pick-up unit 400 crosses a track of optical disc D, the tracking error signal generating the section 410 generates a tracking error signal in a sinusoidal wave form.

To preferentially increase an error amount of a plus (+) side, regardless of a track jump direction of the optical pick-up unit 400, the inverting/non-inverting section 430, responsive to a control signal from the control section 210, does either invert or not invert the tracking error signal from the tracking error signal generating section 410, and outputs the inverting signal or the non-inverting signal of the tracking error signal. This means that the inverting/non-inverting section 430 does not invert the tracking error signal when the optical pick-up unit 400 jumps toward a first jumping direction, i. e., a direction to the outer-radius, and inverts the tracking error signal when the optical pick-up unit 400 jumps toward the second jumping direction, i. e., a direction to the inner-radius.

The peak holding section 440 holds a peak value of the tracking error signal from inverting/non-inverting section 430 and provides the peak value signal of the

tracking error signal to the reference level signal generating section 450.

The reference level signal generating section 450, responsive to the control signal from the control section 490, outputs a reference level signal which is the correspondence of the peak value signal from the peak holding section 440.

The first comparing section 460 compares the level of the tracking error signal arising from the inverting/non-inverting section 430 with the reference level signal from the reference level signal generating section 450. The first comparing section 460 generates a first clock signal of a high level whenever the level of the tracking error signal goes down to the level of the reference level signal, and provides the first clock signal for the control section 490.

The control section 490 obtains an accelerating time and a decelerating time of the track jump of the optical pick-up unit 400 from the first clock signal provided by the first comparing section 460, and controls the jump signal generating section 470 to conduct the track jump corresponding to the accelerating time and the decelerating time.

The jump signal generating section 470 generates a control signal which is one of the first and the second direction jump signals, and provides the control signal to the switching section 480. Additionally, when the track jump of the optical pick-up unit 400 ends, the jump signal generating section 470 applies the jump signal to the driving section 500 in order to operate the driving section 500, and a jump completion signal to the jump status detecting section 510.

The switching section 480 switches its inner path in response to the control signal from the jump signal generating section 470, and provides one of the first and the second direction jump signals to the driving section 500. When the control signal from the jump signal generating section 470 is in a low level, the switching section 480 switches itself in order to have a path between the driving section 500 and the jump signal generating section 470. On the contrary, when the control signal is in a high level, the switching section 480 switches itself in order to have a path between the phase compensating section 420 and the jump signal generating section 470.

The driving section 500, responsive to one of the first and the second direction jump signals which are provided by the switching section 480 from the jump signal generating section 470, provides the driving signal for the optical pick-up unit

400 to jump to either the first direction or the second direction.

The jump status detecting section 510 has a peak detecting section 511, a first comparison level signal generating section 512, a second comparison level signal generating section 513, a second comparing section 514, a third comparing section 515, an OR-gate 516, a first flip-flop 517, and a second flip-flop.

The peak detecting section 511 detects a highest and a lowest peaks of the tracking error signal provided by the inverting/non-inverting section 430, and outputs the highest peak value signal and the lowest peak value signal.

The first comparison level signal generating section 512 outputs a high level comparison signal corresponding to the highest peak signal from the peak detecting section 511. The second comparison level signal generating section 513 outputs a low level comparison signal corresponding to the lowest peak signal from the peak detecting section 511. Here, both the high level comparison signal and the low level comparison signal are the reference levels for checking the track jump status of the optical pick-up unit 400. This means that, if a system error occurs during the jump of the optical pick-up unit 400, the level of the tracking error signal goes up and down abnormally. Accordingly, when the level of the tracking error signal becomes higher than the high level comparison signal or it becomes lower than the low level comparison signal, the track jump status of the optical pick-up unit 400 can be regarded as an abnormal state.

The second comparing section 514 compares the tracking error signal from the inverting/non-inverting section 430 with the high level comparison signal from the first comparison level signal generating section 512, and outputs a second clock signal which has a high level when the tracking error signal is higher than the high level comparison signal.

The third comparing section 515 compares the tracking error signal from the inverting/non-inverting section 430 with the low level comparison signal from the second comparison level signal generating section 513, and outputs a third clock signal which has a high level when the tracking error signal is lower than the low level comparison signal.

The OR-gate 516 logically adds the second clock signal arising from the second comparing section 514 and the third clock signal arising from the third

comparing section 515 to provide the track jump status signal, which represents either a stable status or an unstable status of the track jump, to control section 490. This means that, if the level of the tracking error signal is higher than the level of the high level comparison signal or the level of the tracking error signal is lower than the level of the low level comparison signal, the OR-gate 516 provides a track jump status signal which has a high level to the control section 490. Consequently, when the track jump status signal which has the high level is provided from OR-gate 516, the control section 490 controls the jump signal generating section 470 to quit the track jump of the optical pick-up unit 400.

The first flip-flop 517 receives the second clock signal and the jump completion signal from the second comparing section 514 and the jump signal generating section 470 respectively, and provides an over-jumped status signal, which indicates whether the optical pick-up unit 400 jumped over or not, to the control section 490.

The second flip-flop 518 receives the third clock signal and the jump completion signal from the third comparing section 515 and the jump signal generating section 470 respectively, and provides an under-jumped status signal, which represents whether the optical pick-up unit 400 jumped under or not, to control the section 490. Here, the first flip-flop 517 and the second flip-flop 518 become enable at the rising edge of the jump completion signal from the jump signal generating section 470.

The storing section 520 holds a standard acceleration time and a standard deceleration time which represent the ratio of the peak value of the tracking error signal to the level of the reference level signal for each track jump.

The control section 490 controls the jump signal generating section 470 based on the track jump status signals from the jump status detecting section 510, the first clock signal from the first comparing section 460, and a standard value signal from the storing section 520.

Industrial Applicability In the method and the apparatus for controlling a track search of an optical disc according to the present invention, the optical disc system can reduce a jump error such as an over-jump and an under-jump in the optical pick-up unit, and prevent

an unstable reproduction operation resulted from the instantaneous oscillation of or the bias of the optical pick-up unit from occurring. Also, after the track jump operation of the optical pick-up unit, the optical disc system can reduce a delay time for implementing a normal reproducing operation of the optical disc. As a result of it, the optical disc system can perform the track search accurately and stably.

While the present invention has been particularly shown and described with reference to particular embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be effected therein without departing from the spirit and scope of the invention as defined by the appended claims.

What is claimed is: 1. A method for controlling a track search of an optical disc system, wherein said method comprising the steps of: (i) reading out acceleration data about an optical disc which is currently loaded for reproducing programs recorded on said optical disc from a storage of acceleration information; (ii) implementing a track jump for an optical beam to enter into an area of a target track based on said first acceleration information; (iii) comparing a first signal which represents said target track position with a second signal which represents a current jumping track position to find an error in said track jump; (iv) updating said acceleration information in said storage with new acceleration information of said optical disc which has been compensated by said error to reduce an error in track jump upon a next reproduction of said optical disc, based on said comparison; and (v) implementing an accurate searching for said target track after said track jump by using said first signal and said error.

2. The method as claimed in claim 1, wherein said step (i) comprises the substeps of: (i-1) monitoring an input of a track search key signal; (i-2) inspecting whether said storage holds said updated acceleration information about said optical disc after said input of said track search key signal; (i-3) reading out said acceleration data which was updated latest in the case that updating of said acceleration information has ever been done at least once, and reading out standard acceleration information for said optical disc as said acceleration data in the case that updating of said acceleration information has never been done at least once.

3. The method as claimed in claim 3, wherein said step (iii) comprises the substeps of: (iii-1) storing said acceleration data which was used for said track jump in said