JPH0676313A - Optical disk control device - Google Patents

Abstract

PURPOSE:To enable rapid and accurate moving of an optical head to a position of an aimed track. CONSTITUTION:When an aimed track to be moved is designated and the number of changed tracks to this aimed track is a first defined number N or more, a linear motor 14 being coarse adjusting means is driven, and coarse adjusting of track retrieval is performed. Further, When the number of changed tracks becomes a second defined number NA being not yet attained to the aimed track, two shafts driving means 16 being a fine adjusting means is driven, and fine adjusting of track retrieval is performed. By combining this coarse adjusting and fine adjusting, an optical head 13 can be rapidly and accurately moved to the aimed track without overrunning.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disc control device suitable for application to an optical disc recording / reproducing device such as a compact disc.

[0002]

2. Description of the Related Art Recently, an optical disk such as a compact disk (CD) is used for backing up computer data and the like. In order to reproduce the data recorded on the optical disk, it is necessary to search the track on which the data is recorded. Since the track search time should be short, various optical disk control methods have been proposed.

When a target track to be moved is given to one of the typical control methods (first search method),
There is a method in which the target track is searched at high speed (coarse adjustment), and when the target track is reached, fine adjustment (seek control) is performed to finally search for the target track.

A linear motor provided in the optical head device is used as the rough adjusting means, and a biaxial adjusting means also provided in the optical head device is used as the fine adjusting means.

Another method (second search method) is a method of searching for a target track by performing seek control from the beginning.

[0006]

SUMMARY OF THE INVENTION In the first search method,
As shown by the curve x in FIG. 4, since the coarse adjustment is performed until the target track is reached (time point a), high-speed search is performed.

In this way, when performing a high-speed search, even if the fine adjustment means is switched to when the target track is reached, it normally overruns the target track because it is a high-speed search. Since the target track is searched by the fine adjustment means for this overrun, it takes a further time up to time point b until the target track is finally searched as shown in FIG.

Therefore, according to the first search method, although the time required to reach the target track is very fast, the final search end time is very long, and there is a problem with the accuracy of the search.

The second search method employs two-axis control. When the tracks to be searched are not so far apart from each other (for example, from several tens of tracks to several hundreds of tracks), the two-axis control tilts the optical head in the two axes (x, y directions) of the optical disc to set the target track. Since it is a search, the search speed is not so fast as shown by the curve y in FIG.

Although the search speed is slow and it takes time until the final search end time point c, the target track search is extremely accurate and no overrun occurs.

As described above, the first search method can shorten the search time, but the search accuracy is poor, and the second search method has the high search accuracy, but has a conflicting problem that the search time is long.

Therefore, the present invention solves such a conventional problem, and proposes an optical disk control device which shortens the search time and has a high search accuracy.

[0013]

In order to solve the above problems, according to the present invention, when a target track to be moved is designated, the number of changed tracks up to the target track is equal to or greater than a first specified number. At this time, the coarse adjustment unit is driven to perform the coarse adjustment of the track search, and when the number of changed tracks reaches the second specified number before the target track, the fine adjustment unit is driven to perform the fine adjustment of the track search. It is characterized by being performed.

[0014]

As shown in FIGS. 1 and 2, when a target track to be moved is designated, when the number of changed tracks up to the target track is equal to or larger than the first prescribed number N, a linear functioning as coarse adjusting means is provided. The motor 14 is driven to roughly adjust the track search (steps 51 to 5 in FIG. 2).
4).

When the number of changed tracks reaches the second specified number NA before the target track, the biaxial control means 16 functioning as a fine adjustment means is driven to finely adjust the track search (steps 55 to 55). 60).

As described above, when the predetermined track before the target track is searched, the track search is performed by switching to the fine adjustment. Therefore, the advantages of the first search method (reduction of search time) and the second search method are provided. Can combine the advantages of (track search accuracy).

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a case where an example of an optical disk control apparatus according to the present invention is applied to an optical recording / reproducing apparatus using a CD will be described in detail with reference to the drawings.

FIG. 1 shows an optical recording / reproducing apparatus, particularly an optical disk control apparatus 10 which is a main part of the present invention.

In FIG. 1, reference numeral 11 is a CD, on which predetermined data is recorded and reproduced. 1
Reference numeral 2 is an optical head device, which has an optical head 13 (subject to an objective lens in the figure) as is well known.
The optical head 13 is moved by the linear motor 14 in the radial direction of the CD 11. Reference numeral 15 is a movement guide therefor.

The optical head 13 can also perform tracking adjustment (fine adjustment) by the biaxial control means 16. The biaxial control means 16 is further provided with a control means for focus adjustment so that the biaxial adjustment can be performed, but details thereof are omitted in the drawing.

When a track search is performed, a target track is designated (track data is designated) at the terminal 20, and this is supplied to the track change control means 21 to perform high-speed search by the high-speed drive of the linear motor 14 or two-axis control. Means 16
The low speed search (seek search) is selected.

A first prescribed number N is set as a criterion for the selection, and it is checked whether the target number of tracks is equal to or larger than the first prescribed number N. When the number is larger than the first specified number N, the fast search is selected, and when the number is smaller than the first specified number N, the slow search is selected. The track address information reproduced from the CD 11 is also used for this selection.

When the number is equal to or more than the first specified number N, the setting means 22 sets the number of moving tracks (the number of changed tracks), and the signal corresponding to the number of moving tracks is passed through the track difference detecting means 23 to indicate the target speed. Is supplied to the means 24.

As will be described later, the number of moving tracks is input to the track difference detecting means 23, and the track difference to the target track is obtained according to the number of moving tracks.

The target speed instructing means 24 is for specifying the track search speed, and in this example, it is constituted by a ROM table, and when the input moving track number (corresponding to the track difference detection signal) is large, the fast target speed is set. Is instructed, and a slower target speed is instructed as the number of moving tracks becomes smaller.

When the target speed is designated, this is compared with the current moving speed of the optical head 13 by the comparison means 25, and the linear motor driving means 29 is controlled by the comparison output, and the linear motor is driven at the speed corresponding to the comparison output. 14 is controlled to move.

By driving the linear motor 14, the light beam scans the CD 11, the output is read by the writing / reading means 31, and the recorded data is reproduced by the reproducing means 34.

The reproduced data is supplied to the track address detecting means 35 to obtain the track address.
This track address data is supplied to the track change control means 21 as described above.

In this example, the light beam input to the writing / reading means 31 is also supplied to the tracking error signal generating means built in the writing / reading means 31 to generate a tracking error signal. The tracking error signal is supplied to the moving track number detecting means 32, and the number of tracks on which the optical head 13 is actually moved is detected from the tracking error signal, and the track difference between the moving track number and the target track number to the target track number is detected. Is calculated by the track difference detecting means 23.

The linear motor 14 is provided with speed detecting means 27, which detects the current speed of the optical head 13 through a filter compensating circuit 28 such as a low-pass filter, and this is supplied to the detecting means 25 to detect the target speed. The speed control loop is made so that

At the stage of high speed retrieval, a predetermined fixed value is supplied to the biaxial control means 16 to control the full range. Since the two-axis control means 16 searches for tracks within a specific number of tracks, the number of tracks that it can cover is small. It is usually within the range of about 500 tracks. Therefore, at the high speed search stage, the fixed value output means 40 gives a value (fixed value control signal) capable of jumping to the maximum number of tracks that can be searched by the biaxial control means 16. 37 is a biaxial drive means.

In this example, the ROM table 44 is accessed by the output from the fixed value output means 40, and the data corresponding to the fixed value control signal is read out.

In the track difference detection means 23, the track difference between the target number of tracks and the number of actually moved tracks is also supplied to the second specified number detection means 41,
A comparison with the second specified number NA is made.

The second specified number NA is a value at which the number of tracks up to the target track becomes NA, and in this example, it can be selected to an arbitrary value from several tracks to several hundred tracks. This is because the set number NA differs depending on the range of the number of tracks that the biaxial control means 16 can cover.

In any case, the second specified number detecting means 41 is located at the predetermined number of tracks immediately before the target track.
When the track difference becomes equal to or smaller than the second specified number NA, the detection signal is supplied to the changeover switch 42 and the control signal for driving the two axes is changed over to the control signal based on the tracking error signal. Then,
Now switch to slow search (seek search).

At this time, from the signal indicating the current speed of the linear motor 14 obtained from the speed detecting circuit 27 and the detection output from the second specified number detecting means 41 (the number of remaining tracks up to the target number of tracks), the time point shown in FIG. d (= NA track number)
Biaxial control is performed so that the search speed can be the following curve z. Such speed control is achieved by referring to the data in the ROM table 44.

As the tracking error signal, the tracking error signal obtained from the above-mentioned writing / reading means 31 is used, and this is inputted to the ROM table 44 via the compensating circuit 43 having a filtering function and the changeover switch 42. The referred biaxial control signal is supplied to the biaxial drive means 37, and the biaxial control means 16 is driven by the drive signal.

This two-axis drive state indicates the two-axis position detecting means 16
The two-axis detection output detected by A is supplied to the linear motor drive circuit 29, and the linear motor 14 is driven so that the two-axis detection output becomes zero.

When the target number of tracks instructed from the terminal 20 is smaller than the first prescribed number N, a control signal from the track change control means 21 is supplied to the track jump instruction means 36 in order to select the low speed search processing. A jump of the number of tracks according to the designated target number of tracks is instructed. The two-axis drive means 37 is controlled by this jump signal to perform track search.

Also at this time, the track difference is the second specified number NA.
In the following cases, the changeover switch 42 is controlled to perform the track search process based on the tracking error signal.

It should be noted that, out of the respective means shown in FIG. 1, each means shown in the control means 49 shown in the figure is processed by software under the intervention of a control program, and FIG. It is depicted as a block for the sake of convenience.

FIG. 2 is a flow chart showing an example of a processing flow for realizing such track search processing.

When the target track number is set as shown in the figure, it is checked from the track address determined by the target track and the current position of the optical head 13 whether or not the changed track number is equal to or larger than the first specified number N ( Steps 51 and 5
2).

When the number is equal to or larger than the first prescribed number N, the number of moving tracks is set in step 53 to execute a high speed search (tracking search), and the control of the biaxial control means 16 is fixed to a fixed value (seek control). OFF), and linear motor drive processing according to the target speed is further performed (step 5).
4).

Next, the number of changed tracks is the second specified number NA.
Slow search (seek search) when the search track is compared to the target track and NA track of the target track is searched
It becomes processing.

In the low speed search process, first, the number of remaining tracks or the second specified number NA is set (step 55). The number of changed tracks is N
It is the number of tracks when:

Number of remaining tracks or second specified number NA
Is set, two-axis control is performed, at which time the positions of the two axes are detected and the linear motor 1 is detected according to the two-axis position.
4 is driven (steps 56, 57, 58).

When the ni-linear motor 14 is driven, the motor speed of the linear motor 14 is detected (step 59),
ROM table 4 from this motor speed and the number of remaining tracks
4 is used to determine the biaxial travel (step 6).
0). When such a control operation is continuously performed and the target number of tracks is reached, the biaxial control is stopped (step 6).
1). As a result, the optical head 13 can be moved to the target track position quickly and accurately without overrun.

[0049]

As described above, in the optical disc control apparatus according to the present invention, when the target track to be moved is designated, the rough adjustment is performed when the number of changed tracks up to the target track is equal to or more than the first specified number. The means is driven to perform the rough adjustment of the track search, and the fine adjustment means is driven to perform the fine adjustment of the track search when the number of changed tracks reaches the second specified number before the target track. It was done.

According to this, since the rough adjustment and the fine adjustment are skillfully combined, there is a feature that the optical head 13 can be moved to the target track position quickly and accurately without overrun.

[Brief description of drawings]

FIG. 1 is a system diagram showing an example of a main part of an optical disk control device according to the present invention.

FIG. 2 is a flowchart showing an example of tracking control and seek control.

FIG. 3 is a diagram showing a control operation up to a target position in the present invention.

FIG. 4 is a diagram showing a conventional control operation up to a target position.

FIG. 5 is a diagram showing a control operation up to a target position in the related art.

[Explanation of symbols]

 10 optical disk control device 11 optical disk 13 optical head 14 linear motor 16 two-axis drive means 24, 44 ROM table

Claims (4)

[Claims] 1. When a target track to be moved is designated, when the number of changed tracks up to the target track is equal to or larger than a first specified number, the coarse adjustment means is driven to perform coarse adjustment for track search. An optical disk control device characterized in that when the number of changed tracks reaches a second specified number, which is before the target track, the fine adjustment means is driven to perform fine adjustment for track search. 2. The optical disk control device according to claim 1, wherein a linear motor provided in an optical head device is used as the rough adjusting means. 3. The optical disk control device according to claim 1, wherein a biaxial adjusting means provided in an optical head device is used as the fine adjusting means. 4. The second prescribed number is several tracks to
2. The track is selected as several tens of tracks.
The optical disk control device described.