CN1297965C - A method for improving track jump accuracy in CD-ROM - Google Patents

Abstract

The present invention provides a method for improving track jump accuracy in an optical disc drive. It is briefly described as follows: when calculating a fixed track number of the movable optical head assembly, the optical drive detects a preset grating number; then, an actual track number moved by the optical head assembly when the optical drive detects the predetermined grating number is calculated, so as to obtain the optimal track number/grating number ratio.

Description

A method for improving track jump accuracy in CD-ROM

technical field

The present invention relates to a method for increasing track jump accuracy in optical drives, and more particularly to a method for calibrating the number of tracks/rasters of an optical drive using a DC motor.

Background technique

Generally, when an optical drive receives a read (or write) command from the host (host), its seeking servo system (seeking servo) will first perform the action of jumping (seeking), that is, using the platform motor (sled motor) in the optical drive. ) drives the optical head assembly to move to the target track indicated by the servo system. After the optical drive determines that the optical head has reached the target track (that is, the track is locked), the operation of accessing the optical disc is performed. When the optical drive performs track jumping and access operations, the speed at which the optical head assembly moves will affect the read or write speed of the optical drive.

Also, when jumping tracks (especially during long track jumps), the optical drive will use a raster signal (photo signal) to assist in calculating the track number of the track jumping. The following is a brief introduction to the generation of grating signals and their representative meanings.

Referring to Figure 1 first, it is a circular grating. When the platform motor drives the platform to move, it will drive the circular grating 13 to rotate in the direction 15 . In addition, because a fixed light source is projected at 21, the grating signal will have an amplitude when the light-transmitting portion 17 of the circular grating 13 passes through 21; otherwise, if the opaque portion 19 of the circular grating 13 passes through 21, it will not There is no amplitude produced. Because the interval of the opaque part of the circular grating is fixed, the distance of the trolley jumping track is fixed during the interval of the amplitude of the grating signal generation, as shown in Figure 1 (that is, the ratio of the number of tracks/the number of gratings is A constant; track to photoratio=constant).

Therefore, when the host sends a command to jump 4000 tracks, the optical head assembly has moved 4000 tracks when the optical drive detects 80 amplitudes of the raster signal (assuming that the number of tracks/the number of rasters is 50:1). Thereby, the number of tracks that the optical head assembly jumps during long track jumps can be easily calculated.

However, due to variations in optical disc technology, the optical drive cannot move the optical head assembly to the target track very accurately.

Referring to FIG. 2, the specification of the optical disc is that each track pitch thereof is 1.6 µm. If the track pitch of the optical disc becomes 1.7 μm due to the variation of the optical disc process. That is to say, the 10,000-track distance (from point A to point C) of this optical disc is very different from the 10,000-track distance (from point A to point B) of a general standard optical disc, as shown in FIG. 2 . Generally, the ratio of the number of tracks moved by the optical head assembly to the amplitude of the raster signal is 50:1 (ie, a fixed ratio). When receiving the 10,000 track jump command from the host, under normal circumstances, the optical drive drives the platform motor to drive the optical head assembly to move until the grating signal has 200 amplitudes. Under normal circumstances, the optical head assembly should have moved 10,000 tracks to reach the target track (200 times × 50 tracks). However, because the single track pitch on the optical disc is relatively long, the amplitude of the raster signal appears 200 times but only drives the optical head assembly to move 9400 tracks, which is 600 tracks away from the target track.

The above situation is very unfavorable for the rail locking action carried out after the rail jump. It often takes more time to lock the rail or cause the rail lock to fail. Therefore, it can be seen that the optical drive needs a method to improve the accuracy of the track jump, so that the optical head assembly can correctly reach the target track after the track jump.

Contents of the invention

The object of the present invention is to provide a method for improving the track jumping accuracy of an optical drive. This solves the problem that the disc drive cannot precisely jump tracks due to process variation of individual discs.

The invention proposes a method for improving track jump accuracy in an optical drive. When calculating a fixed number of tracks for moving the optical head assembly, the predetermined raster number that the optical drive should detect; then calculate the actual number of tracks that the optical head assembly moves when the optical head assembly detects the predetermined number of rasters, so as to obtain the optimal number of tracks/ Raster ratio.

In order to further understand the features and technical content of the present invention, please refer to the following detailed description and drawings related to the present invention. However, the drawings are provided for reference and illustration only, and are not intended to limit the present invention.

Description of drawings

Fig. 1 is the schematic diagram of circular grating and grating signal;

Fig. 2 is a diagram showing the track pitch error caused by disc process variation; and

Fig. 3 is a flow chart of the method for improving the accuracy of track jumping in the present invention.

Explanation of the figure numbers of the attached drawings:

100 CD inserted or power on

110 Make the optical head assembly move a predetermined track distance during the initial program

120 Calculate the number of tracks actually moved by the optical head assembly

130 Use this actual number of tracks to correct the track/raster ratio

Detailed ways

Due to variations in optical disc technology, individual optical discs have different track pitches, causing the platform motor to fail to drive the optical head assembly to reach the target track correctly when the optical drive is jumping tracks. This is very unfavorable for the rail locking action after the rail jump, and it often takes more time to lock the rail or cause the rail locking to fail. As a result, it will take a lot of time for the optical drive to read data. In order to overcome the above problems. The invention provides a method for improving the track jumping accuracy in an optical drive.

Referring to FIG. 3 , it is a flowchart of a method for improving track jump accuracy in an optical drive.

Step 100: Inserting a disc or turning on the power.

Step 110: Move the optical head assembly a predetermined track distance during the initial procedure.

Step 120: Calculate the number of tracks actually moved by the optical head assembly.

Step 130: Use the actual moved track number to correct the track number/raster number ratio.

When the disc is inserted (tray in) or power is turned on (power on), usually the optical drive will start some initial procedures (startup procedure). During the initial procedure, the optical drive will initialize all system parameters, and thus the type of disc to be accessed can be known and other information. The present invention promptly introduces the flow of the method for improving the accuracy of track jumping in the initial program.

Firstly, the optical head assembly is moved by a predetermined number of tracks (assuming that the predetermined number of tracks is 10,000), and the preset ratio of the number of tracks to the number of rasters of the optical drive is 50:1. Therefore, under this track number/raster number ratio, the optical drive should detect that the raster signal has 200 amplitude occurrences (that is, the raster number is 200).

Carry out the track jumping action subsequently, promptly finish the track jumping action (promptly track jumping 10000 tracks) when the raster signal of optical drive appears 200 raster numbers. At this time, the number of tracks actually skipped can be obtained by detecting the time position on the optical disc. If the number of tracks actually skipped is only 9000 tracks, it can be seen that the actual track pitch of the optical disc is longer than that of the standard disc. The track number/raster number ratio of the optical drive should be adjusted to improve the track jumping accuracy of the optical drive. Divide the actual track number of 9000 tracks by the predetermined raster number of 200 to obtain a corrected track number/raster number ratio of 45:1. Afterwards, the optical drive uses the corrected track number/raster number ratio to perform track jumping when reading the same optical disc. Unless the power of the optical drive is turned off or the disc is removed (tray out).

Therefore, after the optical disc is inserted into the optical drive, or when the power of the optical drive is turned on and there is an optical disc, the above-mentioned method flow will start. As long as a track jump is performed during the initial program of the optical drive, the optimal track number/raster ratio for reading the optical disc can be obtained.

In addition, the present invention utilizes the actual number of tracks traveled during track jumping to correct the ratio of track number/raster number, which is most suitable for long track jumping. At this time, the defined long track jump is more than 10,000 tracks. Because the track pitch error of disc variation is relatively short and difficult to distinguish during short track jumps, the track pitch error of disc variation is more obvious during long track jumps, and a more accurate track number/raster number ratio can be obtained.

Moreover, the present invention is actually more suitable for an optical drive that uses a DC motor to move the optical head assembly (that is, the platform motor is a DC motor). Most of the optical drives that have raster signals are those that use DC motors. If it uses a stepping motor optical drive, the method of calculating the number of tracks will be a little different. However, it does not mean that the present invention cannot be applied to optical drives using stepping motors.

Therefore, the advantage of the present invention is to use a fixed track jump length in the initial program to inversely calculate the track number/raster number ratio to be adjusted. Afterwards, when the track is jumped, there is no need to make corrections, so that the optical drive can more effectively control the accuracy of the track jump.

Furthermore, another advantage of the present invention is that the time required for track jumping can be effectively increased by the process of the method, and the problem of poor access efficiency caused by variations in the process of individual optical discs can be overcome.

In summary, although the present invention has been disclosed as above with preferred embodiments, it is not intended to limit the present invention, any person of ordinary skill in the art, without departing from the spirit and scope of the present invention, can certainly make various Therefore, the scope of protection of the present invention should be defined by the scope of claims of the patent application.

Claims (7)

1. promote the method for the degree of accuracy of jumping onto the tracks in the CD-ROM drive, comprise the following steps:

When (a) a mobile optical head assembly one pre-orbit determination of calculating was counted, this CD-ROM drive was answered detected one predetermined raster count;

(b) move this optical head assembly and detect this predetermined raster count until this CD-ROM drive;

(c) detect the actual rail number that this optical head assembly is moved when this CD-ROM drive detects this predetermined raster count;

(d) obtain an actual rail number/predetermined raster count ratio, i.e. a rail number/raster count ratio of proofreading and correct according to this actual rail number and this predetermined raster count.

2. the method for claim 1, it is characterized in that: this pre-orbit determination number is more than or equal to 10000.

3. the method for claim 1 is characterized in that: when a discs is placed into, just carry out step (a).

4. the method for claim 1 is characterized in that: when the electric power starting of this CD-ROM drive and a discs exist, just carry out step (a).

5. promote the method for the degree of accuracy of jumping onto the tracks in the CD-ROM drive as claimed in claim 1, it is characterized in that: utilize this optical head assembly of a direct current motor driven, and utilize a grating signal to detect this predetermined raster count.

6. method as claimed in claim 5 is characterized in that: when a discs is placed into, just carry out step (a).

7. method as claimed in claim 5 is characterized in that: when the electric power starting of this CD-ROM drive and a discs exist, just carry out step (a).

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