JP2001331952A - Optical disk device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably and rapidly control the access time for moving a traverse motor to a desired information track. SOLUTION: A traverse motor drive circuit 4 is controlled to drive the traverse motor 3 in the speed change pattern corresponding to a speed profile by detecting the inverse electromotive voltage of a phase at which drive voltage is not applied from the traverse motor 3 using a multiphase motor in an inverse electromotive voltage detecting circuit 7 and changing over the profile to a desired speed profile from the time lag between the inverse electromotive voltage and the drive voltage in a control circuit 8. As a result, the speed change pattern is selected by judging whether there is a margin for the drive of the traverse motor 3 or not and therefore the stable and rapid access control is made possible.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk apparatus for recording or reproducing a signal on a record carrier surface using a converged light beam.

[0002]

2. Description of the Related Art An optical disk apparatus irradiates an information track of about 1.6 μm pitch provided on a record carrier of an optical disk with a light spot of about 1 μmφ, thereby defocusing the light spot and the record carrier surface in a vertical direction. While performing focus control to follow with a precision of ± 0.5 μm, tracking control to follow a track deviation between an information track and a light spot with a precision of about ± 0.1 μm is performed.

When moving to another information track beyond the movable range of the tracking actuator as the first track moving means, the tracking control for causing the light beam to follow the information track is turned off, and the second track moving means is used. Drive the traverse motor.

When a multi-phase motor is used as the traverse motor, if the drive frequency, which is the period of switching from phase to phase, is set too high, the rotation of the motor cannot be followed and stable driving cannot be performed. Therefore, in order to perform stable driving,
The drive is performed with the drive frequency lowered relative to the limit frequency at which drive is possible.

[0005]

If the driving frequency is set too high by using a multi-phase motor as the traverse motor as in the conventional configuration, the rotation of the motor cannot follow and cannot be driven. On the other hand, the driving frequency is set sufficiently low. On the other hand, if the drive is performed with the drive frequency set too low, there is a problem that the access time when moving to another information track beyond the movable range of the tracking actuator becomes long.

According to the present invention, when a multi-phase motor is used for the traverse motor as the second track moving means with a simple circuit configuration, the present invention is driven at a driving frequency close to the limit frequency at which driving is possible. It is therefore an object of the present invention to provide an optical disk apparatus having a short access time for moving from an information track followed by a light spot to another information track.

[0007]

SUMMARY OF THE INVENTION In order to solve this problem, the present invention provides a back electromotive voltage detecting means for detecting a back electromotive voltage of a driving motor, and a driving means for driving the driving motor according to a predetermined speed change pattern. A speed profile switching means for determining a speed profile based on the back electromotive voltage, and an access control means for switching to a speed change pattern according to the speed profile to operate the driving means.

Thus, the drive margin of the drive motor is determined from the time lag between the back electromotive force and the drive voltage, and the drive motor is driven by a speed change pattern corresponding to the speed profile. Make it possible.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first aspect of the present invention is a converging means for converging a light beam radiated from a light source onto a record carrier and irradiating the same with an information track formed on the record carrier in a direction substantially perpendicular to the information track. A track moving means for moving the convergence means, a back electromotive voltage detecting means for detecting the movement of the track moving means by a back electromotive voltage of a drive motor, and a driving means for driving the track moving means according to a predetermined speed change pattern. A speed profile switching means for switching the speed change pattern; and an access control means for switching the speed change pattern by the output of the back electromotive voltage detecting means to operate the driving means.

According to a second aspect of the present invention, in the first aspect, the speed profile switching means switches the driving output applied from the driving means to the driving motor and the output of the back electromotive voltage detecting means at a predetermined speed. The speed change pattern is switched in accordance with the time lag.

According to a third aspect of the present invention, there is provided a converging means for converging and irradiating a light beam emitted from a light source onto a record carrier, and converging the light beam in a direction substantially perpendicular to an information track formed on the record carrier. A track moving means for moving the means, a driving means for driving the track moving means with a predetermined speed change pattern, a speed profile switching means for switching the speed change pattern, and detecting a displacement between the information track and the light beam. A track shift detecting means, a track moving number counting means for detecting a track traversing number based on an output of the track shifting detecting means, and an error between an output of the track moving number counting means and a desired moving number is a predetermined number or more. Access control means for switching the speed change pattern and operating the driving means.

According to a fourth aspect of the present invention, there is provided a converging means for converging and irradiating a light beam emitted from a light source onto a record carrier, and converging the light beam in a direction substantially perpendicular to an information track formed on the record carrier. A track moving means for moving the means, a driving means for driving the track moving means with a predetermined speed change pattern, a speed profile switching means for switching the speed change pattern, and a driving voltage of the driving means applied to the track moving means. Access control means for switching a speed change pattern to operate the driving means.

As a result, the present invention makes it possible to perform access stably and in a short time.

Hereinafter, an optical disk device according to an embodiment of the present invention will be described with reference to the drawings.

(Embodiment 1) FIG. 1 is a block diagram showing a configuration of an optical disk device according to Embodiment 1 of the present invention.

In FIG. 1, 1 is an optical disk as a record carrier, 2 is an optical head as a converging means for converging a light beam on the optical disk 1, 3 is a traverse motor as a track moving means for moving the optical head 3, 4 is A traverse motor drive circuit 5 serving as a drive means is a motor for rotating the optical disk 1, and 6 is a motor drive circuit for driving the motor 5. Here, it is assumed that the traverse motor 3 is configured by a polyphase motor.

Reference numeral 7 denotes a back electromotive voltage detection circuit as back electromotive voltage detection means for detecting a back electromotive voltage of a phase to which the drive voltage of the traverse motor 3 is not applied, and 8 denotes a control circuit. Here, the control circuit 8 has speed profile switching means for determining a speed profile for controlling the change pattern of the moving speed of the traverse motor 3, and access control means for switching the speed change pattern according to the determined speed profile. The speed profile switching means obtains a drive margin of the traverse motor 3 from a time lag between the back electromotive voltage detected by the back electromotive voltage detection circuit 7 and a drive voltage applied to the traverse motor 3 from the traverse motor drive circuit 4, Determine the speed profile.

FIG. 2 shows an example of a speed change pattern indicating a change in speed of the traverse motor 3 at the time of access.

In FIG. 2, in each of the patterns, the speed is gradually increased with the passage of time, becomes a constant speed, and stops when the speed approaches a desired access position at a constant speed. 2A is a speed change pattern to be initially set, and if there is a margin for driving the traverse motor 3, the speed change pattern is shown in FIG. 2B. If the drive of the traverse motor 3 cannot be driven stably, FIG. The speed change pattern is used.

That is, since the speed change pattern in FIG. 2B can move at a high speed, it is possible to access a farther place in the same time, and in a short time when viewed from an access at a predetermined position. Can be accessed. In addition, since the drive margin is guaranteed, stable access is provided. The speed change pattern in FIG. 2C is designed to move at a low speed when the drive of the traverse motor is not stabilized for some reason. The access time becomes longer, but the drive frequency becomes lower. Thus, stable control is ensured.

These speed change patterns are output from the control circuit 8 to the traverse drive circuit 4, and the traverse motor 3 is driven based on the input speed change patterns.

FIG. 3 shows that the traverse motor 3 has three phases (U,
V, W), and shows the lapse of time of the drive voltage and the phase for detecting the back electromotive voltage. In FIG. 3, the phase indicated as "back electromotive detection" indicates the phase for detecting the back electromotive voltage. Other phases indicate the phases to which the drive voltage is applied.

The time t shown in FIG. 3 is a time lag between the time when the driving voltage is applied and the time when the back electromotive voltage is detected. When the time t is within a predetermined time (when a back electromotive voltage can be detected within the predetermined time), it is determined that there is a drive margin, and that the speed profile has a margin (or the speed is increased). Is longer than a predetermined time (when the back electromotive voltage cannot be detected within the predetermined time), it is determined that there is no drive margin (or the control is unstable) and the speed profile has no margin (or the speed is reduced). I do. And
Switching to a desired speed change pattern is performed according to the determined speed profile.

Here, if the back electromotive voltage is detected within a predetermined speed range, stable detection can be performed.

As described above, according to the present embodiment, the back electromotive voltage in the multi-phase motor is detected and the speed profile (ie, the speed change pattern) is controlled based on the detected back electromotive voltage. Can be driven to
Access can be shortened.

In the present embodiment, three patterns of a to c are shown as speed change patterns, but the number of patterns is not limited thereto.

(Embodiment 2) FIG. 4 is a block diagram showing a configuration of an optical disk apparatus according to Embodiment 2 of the present invention. 4, the same components as those in the first embodiment shown in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted.

In FIG. 4, reference numeral 9 denotes a focus error detection circuit, which detects a defocus between the recording carrier surface of the optical disc 1 and the light spot. A focus driving circuit 11 drives a focus actuator (not shown, but located in the optical head 2) that moves the light spot in the focus direction. Reference numeral 10 denotes a focus phase compensation circuit, which includes a focus error detection circuit 9, a focus actuator, a focus drive circuit 11, and a control circuit 14.
Is a circuit for compensating the phase of the focus control system constituted by. Numeral 12 denotes a tracking error detecting circuit, which is a track shift detecting means for detecting a shift between the light spot and the information track of the optical disk 1. A track count circuit 13 is a track movement number counting means for detecting the number of track crossings from the output of the tracking error detection circuit 12. A control circuit 14 outputs a plurality of speed change patterns to execute access.

The control circuit 14 drives the traverse motor 3 via the traverse drive circuit 4 to execute access, and then determines the difference (error) between the number of track traversals output from the track count circuit 13 and the desired number of track movements. Ask. Then, the speed change pattern is switched according to the error. That is, the optimum speed change pattern can be selected from the difference between the target number of track movements and the actual number of track crossings (the presence or absence of a traverse motor margin).

With this configuration, the drive of the traverse motor 3 can be moved stably and at high speed, and as a result, the access can be shortened.

(Embodiment 3) FIG. 5 is a block diagram showing a configuration of an optical disk apparatus according to Embodiment 3 of the present invention. 5, the same components as those of the first embodiment shown in FIG. 1 are denoted by the same reference numerals, and the description thereof will be omitted.

In FIG. 5, a drive voltage detection circuit 15 detects a drive voltage of the traverse motor drive circuit 4. Reference numeral 16 denotes a control circuit which has a plurality of speed change patterns and executes access.

The control circuit 16 detects the output of the drive voltage detection circuit 15, and when the output is lower than the predetermined voltage range, the access is performed by switching the speed change pattern shown in FIG. 2A to the speed change pattern shown in c. When the voltage is higher than the predetermined voltage range, the access is performed by switching the speed change pattern shown in FIG. 2A to the speed change pattern shown in b.

By doing so, the drive of the traverse motor can be moved stably and the access can be shortened.

[0035]

As described above, according to the present invention, the speed change pattern is selected depending on whether or not the driving of the traverse motor has a margin, so that the traverse motor can be driven at a high speed, and the access can be stably and shortened. Can be done on time.

[Brief description of the drawings]

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

FIG. 2 is a conceptual diagram of a speed change pattern.

FIG. 3 is a conceptual diagram showing a traverse motor, back electromotive voltage detection, and a drive voltage.

FIG. 4 is a block diagram of an optical disc device according to a second embodiment of the present invention;

FIG. 5 is a block diagram of an optical disc device according to a third embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Optical disk 2 Optical head 3 Traverse motor 4 Traverse motor drive circuit 5 Motor 6 Motor drive circuit 7 Back electromotive voltage detection circuit 8, 14, 16 Control circuit a 9 Focus error detection circuit 10 Focus system phase compensation circuit 11 Focus drive circuit 12 Tracking Error detection circuit 13 Track count circuit 15 Drive voltage detection circuit

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yasuhiro Yoshioka 1006 Kazuma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. F term (reference) 5D088 NN03 NN12 NN15 NN25 5D117 CC06 EE14 FF14 FF29 JJ02

Claims (4)

[Claims] 1. A converging means for converging and irradiating a light beam emitted from a light source onto a record carrier; a track moving means for moving the converging means in a direction substantially perpendicular to an information track formed on the record carrier; Back electromotive voltage detecting means for detecting the movement of the track moving means by a back electromotive voltage of a driving motor; driving means for driving the track moving means according to a predetermined speed change pattern; and speed profile switching means for switching a speed change pattern. An optical disk device, comprising: an access control unit that switches a speed change pattern according to an output of the back electromotive voltage detection unit and operates the driving unit. 2. The method according to claim 1, wherein the switching of the speed profile switching means switches a speed change pattern in accordance with a time lag between a drive output applied from the drive means to the drive motor and an output of the back electromotive voltage detection means at a predetermined speed. 2. The optical disk device according to claim 1, wherein: 3. A converging means for converging and irradiating a light beam emitted from a light source onto a record carrier; a track moving means for moving the converging means in a direction substantially perpendicular to an information track formed on the record carrier; Driving means for driving the track moving means in accordance with a predetermined speed change pattern; speed profile switching means for switching a speed change pattern; track deviation detecting means for detecting a positional deviation between the information track and the light beam; A track movement number counting means for detecting the number of track traverses based on an output of the deviation detection means; and a speed change pattern switching when an error between the output of the track movement number counting means and a desired movement number is equal to or more than a predetermined number. An optical disk device comprising: an access control unit for operating the unit. 4. A converging means for converging and irradiating a light beam emitted from a light source onto a record carrier; a track moving means for moving the converging means in a direction substantially perpendicular to an information track formed on the record carrier; A driving unit that drives the track moving unit with a predetermined speed change pattern; a speed profile switching unit that switches a speed change pattern; and a driving unit that switches a speed change pattern by a driving voltage of the driving unit applied to the track moving unit. An optical disc device, comprising: an access control unit that operates a computer.