JPH08235768A - Optical disk device - Google Patents

Abstract

PURPOSE: To provide an optical disk device which is capable of fast access by controlling the moving speed of an optical head and the rotational frequency of the disk at an aimed address. CONSTITUTION: A signal reproduced from a disk 1 by an optical head 3 is detected by an address detecting circuit 13 through a RF amplifier 4, a PLL 5 and a synchronization detecting circuit 6 to find its absolute address, which is sent to a controller 14. This controller 14 is inputted with an aimed absolute address to be accessed from the outside of the device and, in response to this input, a thread servo control circuit and a spindle motor servo circuit 12 are controlled to allow fast access.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a constant linear velocity (hereinafter referred to as "C
The present invention relates to an optical disc device that rotates an optical disc by "LV" (abbreviated as "LV") and records and reproduces information data, and particularly relates to an optical disc device that records and reproduces a magneto-optical disc for reproducing a mini disc and the like.

[0002]

2. Description of the Related Art In a compact disc (hereinafter abbreviated as "CD") player, while rotating a CD, a laser spot focused from an optical head is moved along an information track formed as a pit row of data on the CD. Irradiation is performed, and a change in the intensity of reflected light is detected by an optical head to reproduce the information recorded on the CD. That is,
By rotating the CD, the optical head relatively scans in the circumferential direction of the track at a rotational linear velocity to reproduce information. This is the operation principle of the optical disk device in general.

In such an optical disk device, when desired information is accessed (started to be reproduced), the position on the disk of the desired information recorded in the table of contents (hereinafter abbreviated as "TOC") area. Using the information of, that is, the address of the target track and the address of the track where the optical head is currently located, calculate the number of tracks that the optical head crosses before moving to the target track,
Based on the calculated number of tracks, the number of tracks traversed by the optical head is counted as described later (hereinafter, "count").
The optical head is moved to the target track (hereinafter referred to as “seek”).

Conventionally, the count of the number of tracks traversed by the optical head is, for example, RF which is a reproduction signal from the optical head.
It is done using signals. That is, when the optical head is moved in the radial direction of the disk while rotating the optical disk, the laser spot emitted from the optical head crosses the track relatively obliquely. As a result,
The RF signal undergoes amplitude modulation (hereinafter abbreviated as "AM") due to the optical head traversing the track as shown in FIG.

Therefore, as shown in FIG. 3, the number of peaks or troughs of the envelope is counted to count the number of tracks traversed by the optical head. For example, the modulation component by the pit, that is, the frequency component of the pit is removed by a filter or the like, and the signal from which the frequency component of the pit is removed is used.

However, for example, the data pits in a CD are formed with the same recording density as the inner circumference over the entire surface of the disk in order to achieve large-capacity recording on a disk as small as possible, and the rotation speed of the disk is CLV. There is. For example, the rotation speed of a disc is
In the case of ini Disc), it is 1.25 m / sec. The raw bit rate of the data in this case is 4.3218 Mb.
ps, the data is EFM modulated (Eight to Fourteen M
odulation) and recorded.

By the way, the maximum inversion period in the EFM modulation law is the repetition of the frame synchronization signal 11T, and RF
The frequency component of the bit in the signal is a minimum of about 200 kHz
Becomes Here, 1T is a bit period.

On the other hand, for example, the interval between pit rows arranged on a CD, that is, the track interval is 1.6 μm. Therefore, when the number of tracks traversed by the optical head is counted using the envelope of the RF signal as described above, the maximum moving speed of the optical head that can be counted in the radial direction of the CD is 1.6 ×, as can be derived from the sampling theorem. 10 ⁻⁴ × 200 × 10 ³ ÷ 2 = 16 cm / sec.

By the way, the moving speed of the conventional optical head is 1 / th of the above theoretical value of 16 cm / sec in consideration of the fact that the characteristics of the filter used in the actual circuit are not ideal and variations in manufacturing error. 2 is 8 cm / sec.

[0010]

In the case of a device for recording various data other than audio information on a CD or MD, such as electronic computer data, the access time (from input of the target address to the target address) It is earnestly desired to further shorten the time before starting recording or reproduction).

However, in the conventional access method of the optical disk device, the moving speed of the optical head has an upper limit as described above, and if the moving speed of the optical head in the disk radial direction is too fast, the optical head may cross the track. There was a problem that could not be detected accurately.

Further, since the management of the information data is performed by using the absolute address recorded on the track together with the information data, a method of detecting the absolute address and seeking the optical head to the target track can be considered. When seeking, if the moving speed of the optical head in the disk radial direction is increased,
There was also a problem that the absolute address could not be read accurately.

Further, since the rotational speed of the disk is set to CLV after the optical head is moved to the target address, the moving time of the optical head and the subsequent disk rotational speed are matched as the access time to the rotational speed at the target address. Therefore, there is a problem that it takes time.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an optical disk device that can be accessed at high speed by controlling the moving speed of the optical head and the rotational speed of the disk at the target address. To do.

[0015]

In order to achieve the above object, the optical disk device of the present invention is characterized in that, in claim 1, the information track including substantially absolute concentric circular information tracks is optically reproducible. An optical head for reading this information from an optical disc recorded at a constant linear velocity, an address reproducing means for reading the absolute address from the output of the optical head, and an address input means for inputting a target address to be searched from outside the device,
Computation means for computing the moving distance in the radial direction from the output of the address input means and the output of the address reproducing means, and moving means for moving the reproducing head to the target address according to the output of the calculating means. It is a thing.

According to a second aspect of the present invention, the optical disc further includes linear velocity control means for maintaining a constant relative linear velocity between the optical disc and the optical head, and the computing means rotates the optical disc at the target address. It is characterized in that a target rotation speed to be obtained is also obtained and an adjustment signal for adjusting the linear velocity control means is output.

According to a third aspect of the present invention, the linear velocity control means includes means for substantially detecting the rotational speed of the optical disk.

[0018]

With the above construction, in the first aspect, the optical head records this information from the optical disk in which the information including the absolute address is recorded on the optically reproducible substantially concentric information track at a constant linear velocity. After reading, the address reproducing means reads the absolute address from the output of the optical head, and inputs the target address to be searched from the outside of the apparatus to the address input means. At this time, the calculating means calculates the moving distance in the radial direction from the output of the address input means and the output of the address reproducing means, and the moving means moves the reproducing head to the target address according to the output of the calculating means. Since it can be moved, high-speed access can be achieved by controlling the moving speed of the optical head and the rotation speed of the disk at the target address.

According to a second aspect of the present invention, the calculation means further includes linear velocity control means for keeping the relative linear velocity between the optical disc and the optical head constant, and the arithmetic means should rotate the optical disc at the target address. Since the target rotation speed is also obtained and an adjustment signal for adjusting the linear velocity control means is output, high-speed access is possible by controlling the moving speed of the optical head and the rotation speed of the disk at the target address. Become.

Further, in claim 3, the linear velocity control means comprises:
Since it includes means for substantially detecting the number of revolutions of the optical disk, the transition to the target number of revolutions becomes faster, and high-speed access is possible by controlling the moving speed of the optical head and the number of revolutions of the disk at the target address. Becomes

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An optical disk device of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic block diagram showing the configuration of a compact disc player according to an embodiment of the optical disc apparatus of the present invention. In FIG. 1, a disk 1 is rotationally driven by a spindle motor 2 so as to have a specified linear velocity. An error correction code, here CIRC (Cross Interleave Reed Solomon), is recorded on the disk 1.
After being converted into code, the data of the music program that has been subjected to EMF modulation is written as a bit string together with redundant bits such as frame synchronization signal, sub-coding consisting of control bits and address bits, and cyclic code (CRC: Cyclic Redundancy Code). Recorded along the track.

As shown in FIG. 2, the optical head 3 includes optical components such as a laser diode 3a, a collimator lens 3b, a beam splitter 3c, an objective lens 3d, a cylindrical lens 3e, and a photodetector 3f divided into a predetermined arrangement. The recording surface 1a of the disc 1 is irradiated with a laser beam to detect a change in the intensity of the reflected light due to the pits in cooperation with the RF amplifier 4 having a matrix structure, and a focus error signal is detected by, for example, an astigmatic method. The tracking error signal is detected by, for example, the push-pull method or the phase difference method.

That is, by rotating the disk 1 as described above, the optical head 3 relatively scans in the track direction at a speed corresponding to the rotation speed of the disk 1 (hereinafter referred to as "scanning speed in the track direction"). Then, the reproduction signal of the information recorded on the disk 1 is obtained by the optical head 3.

The RF amplifier 4 binarizes the reproduction signal from the optical head 3 and supplies the binarized signal to a phase-locked loop (hereinafter abbreviated as "PLL") 5, and also the focus error signal and the tracking error signal to the focus servo. It is supplied to the control circuit 10 and the tracking servo control circuit 11, respectively.

The focus servo control circuit 10 drives the objective lens of the optical head 3 in the optical axis direction so that the focus error signal from the RF amplifier 4 becomes zero. Further, the tracking servo control signal 11 drives the optical head 3 in the disk radial direction so that the tracking error signal from the RF amplifier becomes zero.

The PLL5 is the 2nd output from the RF amplifier.
The clock signal recorded on the disc 1 is reproduced from the binarized signal. The synchronization detection circuit 6 uses the PLL 5
The frame synchronization signal is detected from the reproduction signal by using the clock signal and the frame synchronization is pulled in, and the synchronization is protected to prevent the frame synchronization from being lost due to the influence of dropout or jitter.

The demodulation circuit 7 performs, for example, EFM demodulation on the binarized signal and converts it into 8-bit data of 1 symbol. The error correction circuit 8 is, for example, a CIRC decoding circuit, performs error correction on the reproduction data from the demodulation circuit 7, reproduces the original music program data, and outputs it from the terminal 9 at a specified data transfer rate.

On the other hand, the spindle motor servo control circuit 1
2 uses the clock signal from the PLL, the frame synchronization signal from the synchronization detection circuit 6, and the control signal from the controller 14 which will be described later to set the rotation speed of the disk 1 so that the PLL 5 is locked. The rotation speed of the spindle motor 2 is controlled.

The address detection circuit 13 detects an absolute address indicating each track position of the disk 1 from the data before demodulation from the synchronization detection circuit 6 and supplies this absolute address to the controller 14.

The controller 14 controls the rotation speed of the disk 1 when the optical head 3 scans the same track and reproduces continuous data, and the target track of the optical head 3 (hereinafter referred to as "target track"). I have it in ROM (Read Only Memory) while moving to
For example, by predicting the rotation speed of the target track of the disk 1 according to the table data as shown in FIG. 4, a control signal for switching the rotation speed is supplied to the spindle motor servo control circuit 12 and the optical head 3 is also supplied. When the disk is moved in the disk radial direction, a control signal is supplied to the sled servo control circuit 15 using the absolute address from the address detection circuit 13.

The sled servo control circuit 15 turns the servo off in response to a control signal from the controller 14 to seek the optical head 3 at high speed in the radial direction of the disk. As a method of controlling the spindle motor servo control circuit 12 from the controller 14, for example, a black and white pattern as shown in FIG. 5 is provided on the surface of the turntable (member carrying the disk 1) of the spindle motor 2. By detecting this with a photo reflector,
A frequency signal corresponding to the rotation speed can be obtained.

Here, the number of divisions of the pattern in FIG. 5 is eight, but any number may be used, and instead of providing the pattern on the turntable, it may be separately provided via a gear or a pulley, for example. Alternatively, the output of the Hall element engaged with the induction type frequency generator or the motor, the phase voltage, or the like may be detected. In the case of a brushed motor, the back electromotive force may be detected.

The relationship between the frequency of the frequency signal and the radial position is stored in a table in the ROM as data, and a control signal to the spindle motor servo control circuit 12 is generated while monitoring the rotation speed. This allows
It is possible to previously stabilize the spindle motor at the predicted number of revolutions on the target track.

As a control method from the controller 14 to the sled servo control circuit 15, the relationship between the gear ratio of the sled motor 16 and the movement amount (that is, the number of tracks) of the optical head 3 in the disk radial direction is constant. As a result, the seek to the target track is monitored by using a sensor such as a photo reflector (for example, the pattern of FIG. 5) in the gear of the sled motor 16, and a control signal is supplied from the controller 14 to the sled servo control circuit 15.

As the sled motor, a stepping motor capable of microstep driving can be used to give a predetermined pulse to control the movement by the number of tracks up to the target track.

Next, the data access operation of the optical disk device shown in FIG. 1 will be described with reference to the flowchart of FIG. In step S1, the controller 14
A seek command is input by a data request from the outside of the device, the absolute address of the target track (hereinafter referred to as "target absolute address") is read, and R is read from the target absolute address.
The rotation speed at the target absolute address of the disk 1 is predicted based on the table data in the OM, and the process proceeds to step S2.

In step S2, the controller 1
4 sends a rotation control signal for changing the rotation speed of the disk 1 to the spindle motor servo control circuit 12 based on the predicted rotation speed at the target absolute address, and proceeds to step S3. Spindle motor servo control circuit 12
Changes the rotation speed of the spindle motor 2 to the rotation speed at the target absolute address by this rotation control signal.

In step S3, the controller 14
Sends a transfer control signal for moving the optical head 3 in the disk radial direction at high speed to the sled servo control circuit 15, and the sled servo control circuit 15 moves the optical head 3 in the disk radial direction at high speed by the transfer control signal.

In step S4, while monitoring the amount of movement of the optical head 3, the optical head 3 is moved to the target absolute address. If the movement to the target track has not been completed, the process returns to step S4, and if the movement has been completed, to the step S4. Proceed to S5. Here, this step S4 is, for example, as shown in FIG.
When a sensor such as the one described above is used, and when a highly accurate stepping motor is used, step S6 indicated by a broken line
Then, the process immediately proceeds to step S5.

In step S5, the rotational speed of the disk 1 is already stable, so that the data can be immediately reproduced from the target track. As a result, it becomes possible to access the target absolute address at high speed in response to the input of the target absolute address.

In the above description, the address is disk 1
It was supposed to be recorded in the pit row previously recorded in
Recording may be performed as a change in the polarization direction like MD, or ADI recorded in the pre-groove in the form of frequency modulation.
A P (ADdress In Pregroove) signal may be used. In this case, even a blank disc with no data recorded,
High-speed access is possible.

Further, the present invention is not limited to the above-mentioned embodiment, and for example, rewritable magneto-optical data such as a CD-ROM in which data for a computer is recorded, a write-once type optical disk device, a data MD, etc. The present invention can be applied to all devices such as a disk device that uses a disk that rotates at CLV. Zone CAV (Constant Angular Velocity)
It can also be used for an optical disc adopting the method.

[0043]

As described above, according to the present invention, claim 1
Then, after the optical head reads this information from the optical disc in which the information including the absolute address is recorded on the optically reproducible substantially concentric circular information track at a constant linear velocity, the address reproducing means determines The absolute address is read from the output of the head, and the target address to be searched is input to the address input means from outside the device. At this time, the calculating means calculates the moving distance in the radial direction from the output of the address input means and the output of the address reproducing means, and the moving means moves the reproducing head to the target address according to the output of the calculating means. Since it is moved, there is an effect that high-speed access can be achieved by controlling the moving speed of the optical head and the rotational speed of the disk at the target address.

According to a second aspect of the present invention, the linear velocity control means for keeping the relative linear velocity between the optical disk and the optical head constant is further included, and the arithmetic means should rotate the optical disk at the target address. Since the target rotation speed is also obtained and an adjustment signal for adjusting the linear velocity control means is output, high-speed access is enabled by controlling the moving speed of the optical head and the rotation speed of the disk at the target address. There is an effect that can be.

Further, in claim 3, the linear velocity control means is
Since the means for substantially detecting the rotation speed of the optical disk is included, the transition to the target rotation speed becomes faster, and high-speed access is enabled by controlling the moving speed of the optical head and the rotation speed of the disk at the target address. Since it is possible to predict the rotation speed of the disk at the target absolute address for the input of the target absolute address and rotate the disk at the target rotation speed before the optical head finishes moving, access This has the effect of shortening the time.

[Brief description of drawings]

FIG. 1 is a diagram showing a C according to an embodiment of an optical disk device of the present invention.
It is a figure which shows the structure of a D player.

FIG. 2 is a diagram showing a configuration of an optical head in the example.

FIG. 3 is a waveform diagram of an RF signal reproduced by the optical head when crossing a track in the example.

FIG. 4 is a diagram showing a relationship between an arbitrary position on a disc and a rotation number in the embodiment.

FIG. 5 is a diagram showing a pattern for detecting the number of rotations of a spindle motor with a photo reflector in the embodiment.

FIG. 6 is a flowchart showing the operation of the controller in the embodiment.

[Explanation of symbols]

 1 Disk 2 Spindle Motor 3 Optical Head 4 RF Amplifier 5 PLL 6 Sync Detection Circuit 7 Demodulation Circuit 8 Error Correction Circuit 9 Terminal 10 Focus Servo Control Circuit 11 Tracking Servo Control Circuit 12 Spindle Servo Control Circuit 13 Address Detection Circuit 14 Controller 15 Thread Servo Control circuit 16 thread motor

Claims (3)

[Claims] 1. An optical head for reading this information from an optical disc in which information is recorded on an optically reproducible substantially concentric circular information track at a constant linear velocity including an absolute address, and from the output of this optical head An address reproducing means for reading the absolute address, an address input means for inputting a target address to be searched from the outside of the apparatus, and a calculation for calculating a moving distance in the radial direction from the output of the address input means and the output of the address reproducing means. An optical disk device comprising: means and moving means for moving the reproducing head to the target address according to the output of the computing means. 2. A linear velocity control means for maintaining a constant relative linear velocity between the optical disk and the optical head, wherein the computing means is a target rotational speed at which the optical disk should rotate at the target address. 2. The optical disk device according to claim 1, further comprising: obtaining an adjustment signal and outputting an adjustment signal for adjusting the linear velocity control means. 3. The optical disk device according to claim 2, wherein the linear velocity control means includes means for substantially detecting the rotational speed of the optical disk.