JP2003203370A - Optical disk drive - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To attain the stable operation of an optical disk drive by preventing the deterioration of servo characteristics due to misalignment between an optical disk and an optical pickup. <P>SOLUTION: In the read or write instruction, an LP control circuit 20 changes over the control to servo control systems (205, 207) having faster convergence to the center of optical axis at the moment when the seek operation to the objective position is finished, and changes over the control to servo control systems (206, 208) having higher stability by the time of the start of read or write accompanied with the actual data operation. In starting write accompanied with the actual data operation, a signal corresponding to the lens position produced from a track error signal is evaluated by an LP evaluating circuit 210, and when the signal exists within a prescribed value, the write operation is carried out while the write operation is stopped when the signal is out of the prescribed value. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk device capable of preventing a servo characteristic from deteriorating due to a deviation of an optical axis and operating stably.

[0002]

2. Description of the Related Art Optical disk devices are CDs, DVDs, CDs
An optical pickup that reads and reproduces recorded information from an optical disc such as -R or CD-RW, or generates a recording pulse on the optical disc to record information, and
The optical pickup is provided with a servo control system capable of finely moving in the radial direction of the optical disk and largely moving in the same direction based on the track error signal.

In a read or write command that occurs during normal operation, a seek operation that moves to a position before the address that starts reading or writing that actually operates data is relatively low depending on the distance between the current address and the target address. Accurate and high-speed moving means, for example, rough seek for moving the carriage using a stepping motor, and relatively high-precision and low-speed moving means, for example, track jump for moving the focus position by the lens of the pickup is executed, The seek operation ends when the focus position of the lens of the pickup reaches the target address. This lens shift that causes deterioration of the quality of the RF signal or the write pulse signal in the read may occur.

[0004]

A large number of optical disk devices have been proposed in the prior art that can prevent the servo characteristics from deteriorating due to the optical axis shift between the optical disk and the optical pickup and can operate stably. For example, according to the "information reading device" disclosed in Japanese Patent Laid-Open No. 11-025, there is proposed a means for correcting a deviation from an actual lens position in a lens position detection unit in a servo system, and correcting the deviation. Has been done. However, for example, when the response of the carriage is bad, there is a possibility that the reading or writing is started in a state where the actual lens position is deviated, and in this case, the signal quality is not optimum.

By the way, when the loop gain is increased, the convergence to the control target becomes faster, but the steady servo itself becomes unstable, and the quality of the RF signal or the write pulse signal in the read may be deteriorated. It is necessary to stabilize the steady servo during read or write with data manipulation.

On the other hand, it is possible to speed up the convergence by increasing the loop gain of the servo system, but there is a limit to the loop gain that can be increased due to the limitation of the phase compensation system.
At the maximum loop gain due to this limitation, it may not be possible to converge to the control target in the time until the start of reading or writing including the waiting time that tends to be shortened for improving access. In this case, in reading, the deteriorated RF signal can be read again, but in writing, a disc that cannot be rewritten cannot be rewritten.
Even if it is a rewritable disc, the write result is always verified, so it cannot be overwritten.

The present invention has been made in view of the above circumstances, and by providing a control means for switching two or more servo control systems having different characteristics, a read operation involving data operation is performed even if the lens shift occurs at the end of the seek operation. It is another object of the present invention to provide an optical disc device that can condense the lens position to the optical axis center by a write command and can prevent the write operation when the signal quality is deteriorated at the start of writing. .

[0008]

According to a first aspect of the present invention, there is provided an optical disc device having a drive unit capable of moving a pickup in a radial direction of the optical disc in a fine and a large amount, and controlling the drive unit. Therefore, it is characterized by having control means for switching two or more servo control systems having different characteristics.

According to a second aspect of the present invention, in the optical disk device according to the first aspect, as the servo control system having different characteristics, at least a fast servo control system that converges to the optical axis center and high stability. It is characterized by having a servo control system.

According to a third aspect of the present invention, in the optical disk device according to the first or second aspect, the control means is
In the read or write command, when the seek operation to the target position is completed, switch to the servo control system that converges quickly to the optical axis center, and the servo control system with high stability until the start of read or write accompanied by actual data operation. It is characterized by switching to.

According to a fourth aspect of the present invention, in the optical disk device according to the second or third aspect, the control means is
The present invention is characterized in that the condition at which the lens position crosses the center of the optical axis or the read or write start time with actual data is switched from the control system with fast convergence to the servo control system with high stability.

The invention according to claim 5 is based on claims 1 to 4.
In the optical disc device described in any one of 1 to 3, when the control means evaluates a signal corresponding to a lens position generated by a track error signal at the start of writing accompanied by an actual data operation, and is within a predetermined range. A write operation is performed, and if the write operation is out of a predetermined range, the write operation is temporarily stopped and the write instruction is executed again.

[0013]

1 is a block diagram showing the internal structure of an optical disk device according to the present invention. In FIG. 1, 1
Is an optical disc which is a recording / reproducing information recording medium, and 2
Is a spindle motor that rotates this optical disk. The spindle motor drive system 3 is the spindle motor 2
Control. An actuator drive system 5 having a tracking drive coil and a feed drive system 6 having a carriage drive motor are driven by a servo control circuit 8 to perform radial movement of a laser diode and a pickup 11 and focus control and tracking control. By doing so, a predetermined position on the optical disc 1 is irradiated with laser light.

The signal detection system 7 detects a TE signal obtained via the pickup 11 as well as an RF signal and the like. Also,
The data processing circuit 9 performs error correction of data detected from the optical disk and data extraction operation, and the CPU 12 controls the entire optical disk device of the present invention based on a program recorded in a built-in memory (not shown). The external interface unit 10 is used for transmitting and receiving commands, data and the like to and from an externally connected host device. The host device represents a personal computer or the like that controls the optical disk device of the present invention. The actuator drive system 5, the feed drive system 6, the signal detection system 7, and the servo control circuit 8 described above are referred to as a lens position (LP) control circuit 20, and prevent deterioration of the servo characteristics due to the optical axis deviation between the optical disc 1 and the pickup 11. A detailed description will be given of an optical disk device that can be stably operated.

FIG. 2 is a block diagram showing the internal structure of the LP control circuit 20, FIG. 3 is a flowchart showing the flow of the operation of the read or write command by the CPU, and FIG. 4 is a state transition diagram of the optical disk device according to the present invention. Fig. 5 shows the conventional L
The internal configuration of the P control circuit is shown in a block diagram. A read signal obtained by reading recorded information from the optical disc 1 or a read or write command is issued in an optical disc device having a pickup 11 capable of recording information by generating a recording pulse for the recordable optical disc 1. The operation in this case will be described in detail below with reference to FIGS.

First, as shown in FIG. 3, when a read or write command is issued from the host device, the optical disk device of the present invention starts a seek operation under the control of the CPU 12 (step S301). The seek operation is a relatively low-precision and high-speed moving means depending on the distance between the current address and the target address, for example, rough seek for moving the carriage using a stepping motor and a relatively high-precision and low-speed moving means, for example, the pickup 11. It is executed in combination with a track jump that moves the focal position of the lens. When the focus position of the lens of the pickup reaches the target address, the seek operation ends (step S302). Then, in the case of a read command, when the pickup 11 reaches the read start position, an actual read operation accompanied by data operation is executed (steps S303, S).
304, S306), in the case of the write command, the actual write operation accompanied by the data operation is executed when the write start position is reached (steps S303, S305, S307).

Further, as shown in the state transition diagram of FIG. 4, the optical disk apparatus of the present invention is in the idle state (IDLE) and receives the read command when the read command or the write command is not issued from the host device. Then, a read PLL (Phase Locked Loop) (not shown) is pulled in, and the seek operation is executed up to the target address before the read start address in consideration of the waiting time for stabilization. In this state, it is in the tracking state, and the read operation is started when the read start address is read. When the write command is received, the seek operation is executed up to the target address before the write start address in consideration of the waiting time for the spindle stabilization and the write PLL to be pulled in and become stable. In this state, it is in the tracking state, and the write operation is started when the write start address is read.

As described above, the seek operation is a relatively low-precision and high-speed moving means depending on the distance between the current address and the target address, for example, a coarse seek for moving the carriage using a stepping motor and a relatively high-precision and low-speed operation. It is executed by combining various moving means, for example, a track jump for moving the focal position by the lens of the pickup 11. The seek operation ends when the focus position of the lens of the pickup reaches the target address. At this point, the signal quality of the RF signal or the write pulse in the read is deteriorated due to the lens shift from the optical axis center caused by the lens position shift at the time of pulling in the track servo or the lens position shift due to the track jump. there is a possibility.

From the target address to the read or write start address accompanied by the actual data operation, the system waits while tracking. In the normal track state, as shown in FIG. 5, the servo that drives the tracking drive coil 54 by the control system (51, 52) that receives the track error signal (TE) indicating the deviation with respect to the track and performs steady gain and phase compensation. A servo control system (5) which receives the output of the above-mentioned control system as an input to the control system and passes through the low-pass extraction filter 55 to generate a signal corresponding to the lens position, and which receives this signal to perform steady gain and phase compensation (5
6, 57, 58), a two-stage servo configuration for driving the carriage drive motor 59 is adopted.

In general, if the loop gain is increased in the servo system, the control target, in this case, the center of the optical axis, that is, the time to converge to the optimum lens position is shortened, but the servo system becomes unstable. In addition, the control target can be reached by increasing the waiting time by increasing the interval between the target address for seek operation and the address for reading or writing with actual data operation, but high-speed access that is important for operability in optical disk devices. Therefore, it is necessary to shorten the waiting time.

For this reason, the optical disk device of the present invention has a high gain servo system that converges quickly but the servo becomes unstable, and a normal gain servo system that is stable but slow converges. A high gain servo control system (amplifier 205, phase compensation filter 207) that emphasizes convergence by providing a carriage control mechanism with two-stage servo
And a servo control system (amplifier 2
06, phase compensation filter 208) switching mechanism (switch determination circuit 209 and switches 221 and 222)
In the read or write command, the tracking state after the seek operation is divided into two states by detecting the start of read or write accompanied by the actual data operation, and the former is used as a high gain servo control system. It was decided to switch the latter to the normal gain servo control system.

If the switching mechanism of the servo control system is a digital servo control circuit using a digital signal processor, the coefficient can be rewritten sufficiently quickly with respect to the behavior of the mechanism, which is easy. In the switching determination, the switching determination circuit 206 manages the state in the read or write command, and in the seek state and the waiting state, a high gain servo control system (205, 207) focusing on convergence.
The state machine is configured to switch to the servo control system (206, 208) of the normal gain, which emphasizes stability, via the switch 212 in actual reading or writing by switching the switch via the switch 211.

In the write command, a signal that is asserted when the signal corresponding to the lens position is within the predetermined value and is negated when the signal corresponding to the lens position is outside the predetermined value (the output of the low-frequency extraction filter 204 is set to the upper limit value and the lower limit value). The AND gate 213 performs a logical product of the results of comparison with the respective values by the comparators 211 and 212), and the latch circuit 21 at the rising edge of the write gate signal indicating the write state used as a switch for light emission, that is, at the start of writing.
4, the LP evaluation circuit 210 is configured by the gate circuit 215 that obtains the logical product of the held result and the write gate signal, and by using this signal as a switch for light emission, the write operation can be virtually stopped. it can. Also,
The write command can be retried by using the logical product (AND gate 216) of the inversion of the holding result and the write gate signal as a signal indicating that the write operation is stopped.

As described above, according to the present invention, the LP control circuit 20 moves to the center of the optical axis at the time when the seek operation to the target position is completed in the read or write command based on the switching judgment control by the switching judgment circuit 206. Of the servo control system (amplifier 205, phase compensation filter 207) that converges quickly and switched to a servo control system (amplifier 206, phase compensation filter 208) with high stability before the start of reading or writing accompanied by actual data operation. Further, at the start of writing with actual data manipulation, the signal corresponding to the lens position generated from the track error signal is evaluated by the LP evaluation circuit 210, and if it is within a predetermined value, the write operation is performed, When it is out of the predetermined value, the write operation is stopped. As a result, even if there is a lens shift at the end of the seek operation, the lens position can be converged to the optical axis center by a read or write command accompanied by data operation, and the signal quality is degraded at the start of writing. It is possible to provide an optical disk device capable of preventing the write operation of the above.

[0025]

According to the first aspect of the present invention, by providing the control means for switching between two or more servo control systems having different characteristics, it is possible to perform a read operation or a data operation even if there is a lens shift at the end of the seek operation. With the write command, the lens position can be converged to the optical axis center,
In addition, at the start of writing, it is possible to prevent the write operation when the signal quality is deteriorated.

According to the second aspect of the present invention, as the servo control system having different characteristics, there are provided a servo control system that quickly converges to the center of the optical axis and a highly stable servo control system, which are switched and used. As a result, it is possible to achieve both a high gain servo system in which the servo converges quickly but the servo becomes unstable and a servo system in which the servo is stable but the normal gain slows down.

According to the third aspect of the present invention, in the read or write command, when the seek operation to the target position is completed, the control system is switched to the one in which the convergence to the center of the optical axis is fast, and the actual data operation is involved. By switching to a highly stable control system before the start of reading or writing, the lens position can be converged to the optical axis center by a read or write command even if there is a lens shift at the end of the seek operation, and at the start of writing. It is possible to prevent the write operation when the signal quality is deteriorated.

According to the fourth aspect of the present invention, the signal corresponding to the lens position generated from the track error signal is compared with the center of the optical axis to detect the time of crossing or the start of reading or writing for actually operating the data. Then, by switching to a stable control system as the servo system at the start point, the optimum recording information read operation or write operation can be realized in the read or write command.

According to the invention described in claim 5, at the start of writing accompanied by the actual data operation, the signal corresponding to the lens position generated from the track error signal is evaluated,
When it is within the predetermined value, the write operation is performed, and when it is out of the predetermined value, the write operation is stopped and the write command is executed again, so that the optimum write information writing operation can be realized in the write command.

[Brief description of drawings]

FIG. 1 is a block diagram showing an internal configuration of an optical disk device of the present invention.

FIG. 2 is a block diagram showing an internal configuration of an LP control circuit shown in FIG.

FIG. 3 is a flowchart of the CPU cited to explain the operation of the embodiment of the present invention.

FIG. 4 is a state transition diagram of the optical disc device cited for explaining the operation of the embodiment of the present invention.

FIG. 5 is a block diagram showing an internal configuration of a conventional LP control circuit.

[Explanation of symbols]

20 LP control circuit 205, 207 Servo control system (205:
Amplifier, 207: Phase compensation filter) 206, 208 Servo control system with fast convergence (206: Amplifier, 208: Phase compensation filter) 210 LP evaluation circuit

Claims (5)

[Claims] 1. An optical disc device having a drive unit capable of moving a pickup in a radial direction of the optical disc in a minute direction and a large amount thereof, wherein two or more servo control systems having different characteristics are provided to control the drive unit. An optical disk device having a switching control means. 2. As the servo control system having different characteristics, at least a servo control system which converges quickly to the optical axis center,
The optical disk device according to claim 1, wherein the optical disk device has a highly stable servo control system. 3. The read / write control control means switches to a servo control system in which a seek operation to a target position is completed in a read or write command and the convergence to the center of the optical axis is fast, and actual read / write operations are performed. 3. The optical disk device according to claim 1, wherein the servo control system is switched to a highly stable servo control system before the start. 4. The control means switches the point of time when the lens position intersects the center of the optical axis or the point of start of reading or writing accompanied by actual data from a control system with fast convergence to a servo control system with high stability. The optical disk device according to claim 2, wherein the condition is met. 5. The control means evaluates a signal corresponding to a lens position generated by a track error signal at the start of writing accompanied by an actual data operation, and if the signal is within a predetermined range, performs a write operation, and a predetermined range. 5. The optical disk device according to claim 1, wherein the write operation is once stopped and the write command is executed again in the other case.