JPH04339324A - Seek device for optical disk - Google Patents

Abstract

PURPOSE:To set the number of track jumps taking into account the number of sectors to be skipped during the track jumps and the number of sectors to be read out at the completion of seek when a seek operation is conducted by a track jump. CONSTITUTION:A control part 10 operates the number of jumps up to an aimed track and calculates jump time-tau up to the aimed track. The control part further calculates the number of sectors equivalent to an rotating angle on both sides from the current sector address and the aimed sector address position, and when the difference of the number of sectors is smaller than a value which is the sum of the number of sectors to be skipped during the track jumps and the number of sectors for reading check of the address, controls the number of track jumps to prevent the overran of the track jump.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disc seek device useful for seeking a target track on an optical disc during playback or recording.

0002

2. Description of the Related Art In the case of an optical disc recording and reproducing apparatus in which spiral data is recorded on the recording surface of an optical disc and the recorded data can be read out,
When reading or writing data, a seek operation is often performed to move a laser beam to a desired recording track at high speed.

[0003] Such a seek operation is normally performed by moving an optical head that irradiates the optical disc with a laser beam in the radial direction of the optical disc, but if the target track is far away from the current track, In some cases, a seek operation that moves the entire optical head is performed, and in the case of several hundred tracks, this is performed by a jump operation (multi-track jump) of the fine track actuator of the optical head.

0004

[Problems to be Solved by the Invention] By the way, when performing a track jump of several hundreds or more and seeking the target track, it is difficult to find the jump destination, considering the position of the laser beam currently irradiated and the time required for the jump. There is a problem in that the seek time is increased because there are cases where the track is overtracked or the track is sought one track ahead of the target track.

That is, in a CAV type disk, as shown in FIG. 3, one revolution is divided into 36 sectors, and spiral tracks T1, T2, T3, . . . Tn
Suppose that the optical disk on which the When attempting to access sector #1 located above the TO, the laser beam follows the trajectory r and lands at point Q, and even if a predetermined track jump is performed, the target sector #1 has gone too far. Become.

[0006] Therefore, at this point, there is a problem in that unless the track jump is performed once more toward the inner circumferential side and a one-track jump is performed, it is not possible to reach sector #1 on the target track. The failure of such a seek operation becomes more serious as the rotational speed of the optical disk becomes faster, so that the access time of the optical disk device becomes relatively longer.

[0007]

[Means for Solving the Problems] The present invention has been made with the aim of solving such problems.When seeking a target track, first, from the current track address to the target track address. track jump means for forming a signal for performing a predetermined track jump based on the output of the first calculation means; A second calculation means for calculating the difference between addresses, and the track jump means is controlled in consideration of the output of the second calculation means, the rotational speed of the optical disk, and the time required for track jump, and the seek always ends. Sometimes the laser beam is controlled so that it can access the front side of the target sector address.

[0008]

[Operation] The number of track jumps is set by calculating the sector address of the current laser beam irradiation position, the time to read the sector address of the target track, the seek speed, etc. Track jumps allow access to sectors of the target track.

[0009]

[Embodiment] Fig. 1 shows a block diagram of the optical disk seek device of the present invention, where 1 is an optical disk on which track addresses, sector addresses, etc. are recorded by pre-pits, and 2 is an optical disk whose rotation speed is constant. A spindle motor 3 indicates an optical head that can irradiate the optical disc 1 with a laser beam and read recorded data from the reflected light, and the objective lens of this optical head 3 is moved in the radial direction of the optical disc 1 by a tracking actuator. Tracking control or track jumping can be performed.

Reference numeral 4 denotes a reproduction RF circuit, the output of which is supplied to a reproduction data processing circuit 6 via a data detection circuit 5. In addition, a system clock is formed by a PLL circuit 7, and by measuring sample pits added to the segments dividing each sector by a counter 8, etc., the sector irradiated with the laser beam can be determined even during track jump. The position can be detected. Also, a part of the RF signal is sent to the servo circuit 9.
As is well known, tracking control, spindle control, focus control, etc. of the optical disk device are performed.

Reference numeral 10 denotes a control unit for controlling the seek operation of the optical disk device, which stores the current track address, sector address, etc. of the optical disk 1, and also stores the target address when a seek operation command is input as described later. Performs calculations to access track addresses, outputs jump commands, etc. Reference numeral 11 denotes a jump pulse generator that generates jump pulses for performing a predetermined number of track jumps according to commands from the control section 10, and its output is injected into the tracking servo loop via the drive circuit 12. Reference numeral 13 indicates a switch that is inverted during seek, and reference numeral 14 indicates a phase compensator of the servo circuit.

15 shows a jump control circuit for correcting the number of track jumps during the seek operation of the present invention;
As will be described later, the jump pulse generator 11 is controlled by the control section 10 through calculations. Note that the jump pulse generator 11 and the jump control circuit 13 are connected to the control section 1.
It can also be built into 0. In the optical disk seek device of the present invention, tracking control of the laser beam irradiated from the optical head 3 is normally performed using a tracking error signal inputted from the switch 13.

When input data for accessing a desired sector of a target track is supplied to the control unit 10, as shown in the flow chart of FIG. With reference to the sector address SP, the target track address TO
Arithmetic processing is performed between and sector address SO. First, by calculating the difference between the current track address TP and the target track address TO, TP - T
At the same time as calculating the number of tracks for jumping between O and generating a predetermined track jump pulse, the seek time τ caused by this track jump pulse is calculated.

Next, the time tS (t
S = number of sectors M/1 rotation time) and number of sectors R required to read and confirm the sector address of the target track at the end point of the seek (this number of sectors R is the sector address of the target track after track jump). (SO - ST ) mod M > τ/St - R is calculated using (SO - ST ) mod M > τ/St - R. (M is the number of sectors in one track) (SO - S
T ) mod M is the number of sectors apart on the circumference between the current sector address and the target sector address, and τ
/St indicates the number of sectors passed during the track jump time.

[0015] When the above formula holds true, the track jump of the initially determined number of track jumps TP -TO is performed as is, and when the above formula does not hold, when the target track is accessed, the target sector address is Since this indicates that the track has passed, the jump control circuit 15 controls the number of track jumps to decrease by one. Then, it jumps to the track one track before the target track, detects the target sector address SO, and completes the access operation.

Although the above embodiment has been described in the case where the track jump is performed toward the outer circumference of the disk, it goes without saying that it can also be applied to the case where the track jump is performed toward the inner circumference of the disk. do not have. However, in this case, the jump control circuit 15 is controlled to increase the number of jump tracks by one track when the above equation does not hold. Note that even if the optical disc is of the CLV system, for discs of the sample servo system, the sector address on each track can be read by counting the clock pits, and jump control can be performed using the above formula. It becomes possible.

[0017]

As explained above, the optical disk seek device of the present invention can detect the number of sectors between the current sector address and the target sector address, the time required to read the sector address on the target track, and the number of sectors between the current sector address and the target sector address. Since the number of track jumps is set in consideration of time etc., the seek operation of passing the target sector after a track jump and performing the seek operation again is eliminated, and the seek time is shortened. There is an effect.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an optical disc seek device according to the present invention.

FIG. 2 is a flowchart for setting a track jump.

FIG. 3 is an explanatory diagram of a seek operation performed during a track jump.

[Explanation of symbols]

1 Optical disc 2 Spindle motor 3 Optical head 4 Regeneration circuit 5 Data detection circuit 6 Reproduction data processing circuit 7 PLL circuit 8 Counter 9 Servo circuit 10 Control section 11 Jump pulse generator 15 Jump control circuit

Claims (1)

[Claims] 1. A seek device for an optical disk in which one orbital track is divided into sectors, comprising means for calculating a difference in the number of tracks between a target track address and a current track address, and a track jump corresponding to the difference in the number of tracks. A track jump means for forming a signal, and an arithmetic means for calculating the difference number of sectors between the current sector address and the target sector address, and the difference number of sectors is the number of sectors required for reading the sector address + jump. An optical disc characterized in that the optical disc is provided with a control means for moving the output of the track jump means by one track with respect to the target track jump number when it is predicted that the number of sectors is smaller than the number of sectors to be passed during the time. Seek device.