Track-jump control device and method thereof

The invention relates to a track-jump control device, and in particular, to a track-jump control device for determining track-jump timing in an optical disc drive. A track-jump control device of a PUH comprises an L/G position indicator, a header alignment controller, and a jump controller. The L/G position indicator calculates an amount of sectors between the current position and an upcoming L/G switch point to generate a distance value. The header alignment controller controls the destination position locating in a safe area between two headers, and then generating a jump enabling signal. The jump controller coupled to the L/G position indicator and the header alignment controller determines track-jump timing according to the distance value and the jump enabling signal.

BACKGROUND

The invention relates to a track-jump control device, and in particular, to a track-jump control device for determining track-jump timing in an optical disc drive.

In recent years, there is a need to utilize high-capacity and re-writable recording medium (e.g. DVDRAM) to store all kinds of data. Take a DVDRAM as an example, it has predefined data (also called a header) at the beginning of each sector, for addressing, and to meet a need for random access. The addressing capability of a DVDRAM is similar to that of a hard disk. Since each sector has a predefined data for addressing, both lands and grooves in a DVDRAM must store user data to ensure that the total capacity of DVDRAM does not decrease. If the spot of the PUH suddenly encounters a polar transition in lands and grooves when track-jumping finishes, the read servo will fail easily, particularly at high-speed. Additionally, if the spot of the PUH encounters a header in a sector when a track-jump has finished and enters into the closed loop process , the read servo will also fail easily.

SUMMARY

An object of the invention is to provide a track-jump control device of a PUH. The PUH generates a light spot on an optical disc. The optical disc comprises a plurality of L/G tracks. Each land and groove comprises a plurality of sectors and being connected in an L/G switch point. Each sector comprises a header to indicate the location information of the sector. The track-jump control device determines track-jump timing of the PUH to jump from a current position in a current sector of a current land/groove (L/G) track to a destination position in a destination sector of a destination L/G track.

The track-jump control device comprises an L/G position indicator, a header alignment controller, and a jump controller. The L/G position indicator calculates an amount of sectors between the current position and an upcoming L/G switch point to generate a distance value. The header alignment controller controls the destination position locating in a safe area between two headers, and then generating a jump enabling signal. The jump controller coupled to the L/G position indicator and the header alignment controller determines track-jump timing according to the distance value and the jump enabling signal.

Another object of the invention is to provide an L/G position indicator and a jump controller. The L/G position indicator calculates an amount of sectors between the current position and an upcoming L/G switch point to generate a distance value. The jump controller coupled to the L/G position indicator determines track-jump timing according to the distance value. The L/G position indicator further comprises an address decoder and a calculation unit. The address decoder receives and decodes addresses from a radio frequency (RF) signal and a header signal to generate decoded addresses. The calculation unit coupled to the address decoder calculates the distance value according to the decoded addresses.

A further object of the invention is to provide a header alignment controller and a jump controller. The header edge detector controls the header of current position aligning to an aligning header in the destination track, and detecting a delay value for the destination position in the safe area. The timing control unit coupled to the header edge detector generates the jump enabling signal after delaying a predetermined delay time N according to the delay value The header alignment controller further comprises a header edge detector and a timing control unit. The header edge detector controls the header of current position aligning to an aligning header in the destination track, and detects a delay value for the destination position in the safe area. The timing control unit coupled to the header edge detector generates the jump enabling signal after delaying a predetermined delay time N according to the delay value.

A further object of the invention is to provide a track-jump control method applied in a track-jump control device of a PUH. The method comprises: calculating an amount of sectors between the current position and an upcoming L/G switch point to generate a distance value; controlling the destination position locating in a safe area between two headers, and then generating a jump enabling signal; and determining track-jump timing according to the distance value and the jump enabling signal.

A further object of the invention is to provide a track-jump control method applied in a track-jump control device of a PUH. The method comprises: calculating an amount of sectors between the current position and an upcoming L/G switch point to generate a distance value; and determining track-jump timing according to the distance value. The step of calculating the amount of sectors further comprises: receiving and decoding addresses from a radio frequency (RF) signal and a header signal to generate decoded addresses; and calculating the distance value according to the decoded addresses.

Yet another object is to provide a track-jump control method applied in a track-jump control device of a PUH. The method comprises: controlling the destination position locating in a safe area between two headers, and then generating a jump enabling signal; and determining track-jump timing according to the jump enabling signal. The step of controlling the destination position further comprises: controlling the header of current position aligning to an aligning header in the destination track, and detecting a delay value for the destination position in the safe area; and generating the jump enabling signal after delaying a predetermined delay time N according to the delay value.

DETAILED DESCRIPTION

A detailed description of the invention is provided in the following. Please refer toFIG. 1.FIG. 1is a block diagram of an optical disc drive100according to an embodiment of the invention. The optical disc drive100comprises a disc102, a RF amplifier and servo signal processor104, a slicer106, a phase locked loop (PLL)108, a track-jump control device110, a servo controller114, a driver116, a spindle motor118, and a pick-up head (PUH)120. The disc102is a re-writable recording media, e.g. a DVD-RAM disc. The disc102comprises a plurality of L/G tracks. Each land and groove comprises a plurality of sectors and being connected in an L/G switch point. Each sector comprises a header to indicate the location information of the sector. The RF amplifier and servo signal processor104processes signals from the PUH120to generate a radio frequency (RF) signal SRFand a header signal HD. The slicer106generates an Eight-to-Fourteen Modulation (EFM) signal SEFM according to the RF signal SRF, and then the PLL108generates a PID information according to the EFM signal SEFM. The track-jump control device110determines track-jump timing and outputs a jump enabling signal JMP_EN to enable the track-jump according to the PID information and the header signal HD. The track-jump is from a current position in a current sector of a current land/groove (L/G) track to a destination position in a destination sector of a destination L/G track. The detailed description of other elements in the optical disc drive100is omitted since the functionally and operation are known to those skilled in the art. Further discussion about the track-jump device of the invention is detailed in the following.

Please refer toFIG. 2andFIG. 3at the same time.FIG. 2is a block diagram of a track-jump control device200in the disc drive100according to an embodiment of the invention.FIG. 3shows the timing relationship of a Push-Pull signal ReadCh2, a land/groove switch signal L/G, a tracking error TE, and a tracking error output signal TRO (not shown) in the optical disc drive100. The track-jump control device200comprises an L/G position indicator210, a header alignment controller220, and a jump controller (e.g. a micro-processor)230. In the beginning, the jump controller230sends a request signal JMP_ST for track-jumping. The L/G position indicator210calculates an amount of sectors between the current position and an upcoming L/G switch point to generate a distance value Num_near_LG (seeFIG. 3). The header alignment controller220controls the destination position locating in a safe area between two headers, and then generates a timing enabling signal TIME_EN. The safe area could be the middle area between the two adjacent headers or could be a offset apart from the destination header, etc. The jump controller230finally determines track-jump timing according to the distance value Num_near_LG and the timing enabling signal TIME_EN to output a jump enabling signal JMP_EN. Detailed description of determining track-jump timing will be discussed later. The operation and functionality of the L/G position indicator210and the header alignment controller220is described in the following.

The L/G position indicator210further comprises an address decoder212and a calculation unit214. The address decoder212receives and decodes addresses from the RF signal SRFand a header signal HD to generate decoded addresses. The header signal HD comprises the address information which can be decoded and analyzed to get the distance far from the upcoming L/G switch point. In this embodiment, The header information is decoded from the current header in the current track. In other embodiments, the header information can be decoded from the destination header in destination track. The calculation unit214coupled to the address decoder212calculates the distance value Num_near_LG according to the decoded addresses.

The header alignment controller220further comprises a header edge detector222and a timing control unit224. The header edge detector222controls the header of current position aligning to an aligning header in the destination track, and detects a delay value for the destination position in the safe area. The timing control unit224generates the timing enabling signal TIME_EN after delaying a predetermined delay time N according to the delay value. The predetermined delay time N is designed to ensure that the track-jump is finished in the middle of two headers of two adjoining sectors in the destination L/G track after jumping. For example, at a specific transfer rate, if the optical disc drive100needs 93 us to pass a sector and needs 240 us to accomplish the track-jump, a pass-header jump timing should be set at the 85.5 us after the PUH pass the current header of the current sector, or can be set at the 7.5 us before the current header. When the header edge detector222gets the pass-header jumping timing and the current position, the header edge detector222can easily get the header delay value. For another example, at another specific transfer rate, if the optical disc drive100needs 190 us to pass a sector and needs 240us to accomplish the track-jump, a pass-header jump timing should be set at the 45 us after the PUH pass the current header of the current sector, or can be set at the 140 us before the current header. Detailed description of determining track-jump timing is discussed in the following.

The jump controller230determines track-jumping if the distance value Num_near_LG is larger than a predetermined threshold value J plus K and a delay value is achieve at the same time. J represents an amount of sectors being crossed during track-jumping, and K represents a predetermined safe value. For example, at a specific transfer rate, J is equal to 3

(⌊24093⌋)
if the optical disc drive100needs 93 us to read a sector and needs 240 us to finish the track-jump. And K is predetermined as 3, so the predetermined threshold values is 6 (J+K=3+3=6). That means the distance value decode from the current header must lager than 6, and the jump controller230could generate a jump start signal JMP_ST to the header alignment controller220to get a timing enabling signal TIME_EN.

Please refer toFIG. 4in conjunction withFIG. 2andFIG. 3.FIG. 4is a flowchart illustrating a method for determining track-jump timing in the optical disc drive100according to the invention. The track-jump control device200detects the current track (or the destination track) and the current transfer rate to calculate the threshold value J plus K, the distance value Num_near_LG, and the delay time N (step S410and step S420). The jump controller230then determines whether the distance value Num_near_LG is greater than the threshold value J plus K (step S430). If the distance value Num_near_LG is greater than the threshold value J plus K, the jump controller230goes to step S450. Otherwise the track-jump control device500keeps seeking a track to overtake the L/G switch point (step S440). The timing control unit224generates the timing enabling signal TIME_EN when the destination position could be located in the safe area between the adjacent two headers. (step S450and S460). Otherwise, the timing control unit224keeps delaying (step S470).

Please refer toFIG. 5andFIG. 6at the same time.FIG. 2is a block diagram of a track-jump control device500in the disc drive100according to another embodiment of the invention.FIG. 6shows the timing relationship of a Push-Pull signal ReadCh2, a land/groove switch signal L/G, a tracking error TE, and a tracking error output signal TRO (not shown) in the optical disc drive100. The track-jump control device500comprises an L/G position indicator510, and a jump controller (e.g. a micro-processor)520. In the beginning, the jump controller520sends a request signal JMP_ST for track-jumping. The L/G position indicator510calculates an amount of sectors between the current position and an upcoming L/G switch point to generate a distance value Num_near_LG (seeFIG. 6). Detailed description of the operation and functionality about the L/G position indicator510is omitted for the sake of brevity since it is mentioned in the previous embodiment. The jump controller520finally determines track-jump timing if the distance value Num_near_LG is larger than a predetermined threshold value J plus K.

Please refer toFIG. 7in conjunction withFIG. 5andFIG. 6.FIG. 7is a flowchart illustrating a method for determining track-jump timing in the optical disc drive100according to the invention. The track-jump control device500detects the current track (or the destination track) and the current transfer rate to calculate the threshold value J plus K and the distance value Num_near_LG (step S710and step S720). The controller520then determines whether the distance value Num_near_LG is greater than the threshold value J plus K (step S730). If the distance value Num_near_LG is greater than the threshold value J plus K, the controller520outputs a jump enabling signal JMP_EN to enable the track-jump (step S740). Otherwise the track-jump control device200keeps seeking a track to overtake the L/G switch point (Step S750). Please refer toFIG. 8andFIG. 9at the same time.FIG. 8is a block diagram of a track-jump control device800in the disc drive100according to another embodiment of the invention.FIG. 9shows the timing relationship of a Push-Pull signal ReadCh2, a land/groove switch signal L/G, a tracking error TE, and a tracking error output signal TRO (not shown) in the optical disc drive100. The track-jump control device800comprises a header alignment controller810, and a jump controller (e.g. a micro-processor)820. In the beginning, the jump controller820sends a request signal JMP_ST for track-jumping. The header alignment controller810controls the destination position locating in a safe area (e.g. a point C_L inFIG. 9) between two headers, and then generates a timing enabling signal TIME_EN. Detailed description of the operation and functionality about the header alignment controller810is omitted for the sake of brevity since it is mentioned in the previous embodiment. The jump controller820determines track-jumping to output a jump enabling signal JMP_EN after receiving the timing enabling signal TIME_EN.

Please refer toFIG. 10in conjunction withFIG. 8andFIG. 9.FIG. 10is a flowchart illustrating another method for determining track-jump timing in the optical disc drive100according to the invention. The track-jump control device800detects the current track (or the destination track) and the current transfer rate to calculate the delay time N (step S910and step S920). The timing control unit814generates the timing enabling signal TIME_EN when the destination position could be located in the safe area between the adjacent two headers. (step S930and S940). Otherwise, the timing control unit814keeps delaying (step S950).

Compared with the related art, the track-jump control device according to the invention can prevent to encounter a header in a sector during a closed loop process of track-jump or to avoid encountering a polar transition in lands and grooves during a track-jump, thus increasing the rate of successful track-jumps. Additionally, please note that the number of tracks of a track-jump equal to 1 in the previous description is not taken to be a limitation. The number of tracks can be any positive value.