JP3249893B2 - Disk drive - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to relates to a disk drive equipment for moving the optical pickup to the target track in the optical disc drive device if e example.

[0002]

2. Description of the Related Art Conventionally, when a load is moved to a target position by a stepping motor, it is performed by rotating a rotor of the stepping motor in a unit of a basic step angle determined by an angle of an exciting phase (stator coil).

[0003]

However, in the conventional stepping motor driving device, when the load is moved to the target position by the stepping motor, the operation is performed in units of the basic step angle of the stepping motor. There is a problem that the load cannot be moved to the target position at a smaller angle.

Further, in an optical disk drive device in which an objective lens is mounted on the optical pickup and the objective lens can move relative to the optical pickup so as to follow the track of the disk, the optical pickup is moved in the radial direction of the disk by a stepping motor. For example, when the stepping motor rotates at the basic step angle, the optical pickup moves a distance of about 160 μm, and when the allowable offset of the center position of the objective lens is ± 40 μm due to the eccentricity of the disc, the optical pickup moves. There is a problem that settling (vibration) of the pickup occurs, and skipping of sound and address (CD, CD-ROM) occur.

When the track of the disk is spiral, the objective lens always moves so as to follow the track, and the center position of the optical pickup and the position of the objective lens constantly change. The optical pickup must be moved to within 40 μm.

[0006] The purpose of the present invention, pickup is the purpose of theft
When seeking to the rack position, the stepping motor
In seeking, the objective lens is shifted from the neutral position.
Racking adjustment)
Correction by moving the pickup slightly (objective lens
To the neutral position).
An object of the present invention is to provide a disk drive device that does not need to perform a locking adjustment .

[0007]

[0008]

[0009]

[0010]

[0011]

[0012]

[0013]

[0014]

[0015]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a pickup having an objective lens for condensing a laser beam on a disk surface, a stepping motor for moving the pickup along a radial direction of the disk, and the stepping motor. of the disk drive and a drive means for applying an excitation current or voltage to the exciting coil, the rotor of the stepping motor, advance together confer pressurized large a static friction than the detent torque, the Control means for controlling the exciting current or voltage of the stepping motor so that a torque larger than the applied pressure acts on the rotor, and after the pickup is moved to a target track position, the control means excites the stepping motor. Controlling the current or voltage to control the stepping motor It is achieved by fine movement of the pickup by small rotation.

Furthermore, pairs objective lens is made possible tracking adjustment, control means controls the excitation current or voltage of the stepping motor based on a deviation signal indicating the amount of displacement from a predetermined position of the objective lens Te, the objective lens may be those as Ru <br/> said stepping motor is small rotated by slight moving the pickup to move to a predetermined position.

[0017]

[0018]

[0019]

[0020]

[0021]

[0022]

[0023]

[0024]

[0025]

[0026]

[Function] For the rotor of the stepping motor,
The preload, which is the static friction larger than the detent torque, is
And the control means applies a torque greater than the preload.
Excitation current of the stepping motor so that
Or, control the voltage and rotate the stepping motor slightly.
To move the pickup slightly .

[0027]

[0028]

[0029]

[0030]

[0031]

[0032]

[0033]

[0034]

[0035]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of a stepping motor driving device according to the present invention, FIGS. 2 (a) and 2 (b) are explanatory diagrams showing the configuration of the stepping motor of FIG. 1, and FIGS.
(b) is an explanatory diagram showing a drive control signal and a drive signal of the stepping motor of FIG. 2, FIG. 4 is an explanatory diagram showing an exciting direction of an exciting coil of the stepping motor of FIG. 2, and FIG. FIG. 6 is an explanatory diagram showing the speed at the time of seeking, FIG. 6 is a flowchart for explaining the operation at the time of seek in FIG. 4, and FIGS. 7A to 7C are explanatory diagrams showing the operation when the optical pickup is slightly moved. FIG. 8 is an explanatory view showing a moving torque when the optical pickup is slightly moved, and FIG.
(a) and (b) show the detailed operation of the portion A in FIG. 8, (a) is a steady deviation integrated value-time characteristic diagram, and (b) is a stepping motor drive current-time characteristic diagram.

FIG. 1 shows an optical pickup (PU) as an example.
The shows a stepping motor drive for moving in a radial direction of the disk (sea h). Here, as is known, the optical pickup is provided with a laser diode, an objective lens, an optical system for detecting a tracking error signal, which is an error between the objective lens and a target track, based on reflected light from a disk, and the like. The objective lens can be moved (dense seek, kick) in the radial direction of the disc with respect to the optical pickup, and its maximum range is, for example, ± 10
It is about 0 tracks (± 40 μm).

The stepping motor (STM) 15 has, for example, two phases having an A phase and a B phase as shown in FIG. 2, and has excitation coils 151 to 154 and a rotor 155. Therefore, the basic step angle of the stepping motor 15 is determined by the exciting coils 151 to 154 and the rotor 155.

The rotor 155 of the stepping motor 15 is
As shown in FIG. 4, the excitation directions (directions of current I) of the phases A and B when rotating 360 ° are as follows: A-phase → / A-phase, B-phase without excitation A-phase → / A-phase, B-phase → / B phase A phase is not excited, B phase → / B phase / A phase → A phase, B phase → / B phase / A phase → A phase, B phase is not excited / A phase → A phase, / B → B-phase A-phase has no excitation, / B → B-phase A-phase → / A-phase, / B → B-phase, and the rotor 155 makes one rotation in the steps of

Returning to FIG. 1, the tracking drive signal TR
(Hereinafter, TR signal) is a deviation signal from the neutral position in the pickup of the objective lens provided in the optical pickup and obtained from the optical pickup. The integration circuit 11 integrates the TR signal to obtain a movement torque of the optical pickup, and applies the movement torque to the microprocessor (MCU) 12.

The MCU 12 sends a 4-bit control signal (driver IC 14) for rotating the stepping motor 15 in eight different steps to the four input terminals IN1 to IN4 of the driver IC 14 as shown in FIG. ), And outputs a PWM signal having a variable pulse width in order to determine the drive current or voltage of the stepping motor 15 (hereinafter simply referred to as current). This PWM signal is converted into an analog voltage by the integration circuit 13 and the driver IC 14
Are applied to the terminals VC1 and VC2.

The driver IC 14 has a value proportional to the analog voltage from the integration circuit 13 and supplies drive currents in eight directions as shown in FIG.
5, the rotor 155 of the stepping motor 15 is rotated with a variable torque by applying the voltage to the excitation coils 151 to 154 (A, B). In the present invention, the rotor 155 of the stepping motor 15 is given a preload (static friction) larger than the detent torque for holding the position of the rotor 155 by the magnet in the stepping motor 15 in advance.

Excitation coil 15 of stepping motor 15
The current flowing through the circuit Nos. 1 to 154 is determined by the resistance R
The current is detected by the current detection circuit 16 and monitored by the MCU 12. The MCU 12 catches the change in the detected current,
The switching timing of the excitation phase (the current flowing through the excitation coils 151 to 154) is determined to prevent step-out.

Next, the operation when the optical pickup seeks to the target track at the speed shown in FIG. 5 will be described with reference to FIG. In FIG. 5, the sections to indicate acceleration section, constant speed section, deceleration section,
The section is a settling waiting section, the section is a continuous reproduction section (hereinafter, pseudo microstep), the section is a movement (kick) section of the objective lens, and the section is a continuous reproduction section (excitation switching sections shown in FIGS. 3 and 4). Absent).

In FIG. 6, when a current position (track) and a target position are given, the number of steps corresponding to the difference is calculated, and this processing is started. First, the tracking servo is turned off (S1), and then the step rate is increased in the acceleration section, the step rate is made constant in the constant speed section, and the step rate is decreased in the deceleration section to seek the optical pickup (S2).

Here, the seek distance is the basic step distance ×
Number of steps. In this case, the stepping motor 15
When the motor rotates, the back electromotive force is generated in proportion to the torque (the current changes at the rotor position), so that the stepping motor 15 does not step out and stably seeks.
When the current of the stepping motor 15 is equal to the current detecting resistors R and S
The current is detected by the TM current detection circuit 16 and monitored by the MCU 12, and the excitation phase is switched.

Then, in the continuous reproduction section, as will be described later, control is performed to slightly move the load to the target position at an angle smaller than the basic step angle of the stepping motor (hereinafter, pseudo micro step). That is, the tracking servo is turned on to read the address from the disk, and the mode temporarily shifts to the continuous reproduction mode (S3).

Next, it is determined whether or not the track is the target track based on the address read from the disk (S4). If the track is the target track, a pseudo micro step is performed to shift to the continuous reproduction mode (S4 → S5). On the other hand, if it is not the target track, it is determined whether a seek is necessary up to the target track (S4 → S6).

Here, the case where the seek is necessary up to the target track is the case where the objective lens is not able to jump to the target track by kicking. In this case, the process returns to step S1. On the other hand, if the seek is not necessary up to the target track, the tracking servo is turned off (S
7), the objective lens is kicked to a target track (S8).

Next, the pseudo micro step will be described with reference to FIGS. FIG. 7A shows an on-track state (continuous reproduction mode).
Is located at the center O of the optical pickup 21. When the track 24 on the disk 23 is in a spiral shape, the lens 22 follows the track 24 by the tracking servo with the rotation of the disk 23, and becomes stationary between the lens 22 and the lens neutral point in the optical pickup 21. A deviation TR occurs (FIG. 7B).

In this case, the lens 22 moves following the track 24 to a certain position, and as shown in FIG.
5 (in FIG. 1, the MCU 12 is the driver I
When the pulse width of the PWM signal applied to C14 exceeds the preload applied to the stepping motor 15, the stepping motor 15 is driven, and the optical pickup 21 starts moving. Therefore, as shown in FIG. 7C, when the lens 22 moves by the steady deviation TR, it reaches near the target track. In this case, as shown in FIG. 8, since the integral value of the steady-state error TR decreases rapidly, the driving torque of the stepping motor 15 decreases. And the stepping motor 1
The pickup 21 stops when the drive torque of the pickup 5 becomes smaller than the predetermined pressure. At this time, the lens 22 follows the track 24 by the tracking servo, and the pickup 2
It returns to the approximate center position of 1 and the steady-state deviation TR returns to 0. The excitation switching timing when the stepping motor 15 is slightly rotated is such that when the stepper drive current is monitored and the current exceeding a certain value flows and the integrated value of the steady-state error does not decrease (the pickup 21 does not move), the phase shifts to the next phase. Switch.

FIG. 9 shows the detailed movement of the part A in FIG.
(a) and (b). In this figure, in the section B1, the stepping motor 15 rotates slightly and the steady-state error decreases, and in the section B2, the stepping motor 15 does not rotate even if the current is increased unless the excitation phase is switched. Section B
In step 3, the current is lowered to switch the excitation phase, and in section B4, the current is gradually increased (the stepping motor 15 does not rotate because the generated torque is smaller than the preload).

[0052]

According to the first and second aspects of the present invention, the pitch
When the seek seeks to the desired track position,
Objective lens is in neutral position when seeking with ping motor
It is assumed that it is shifted (tracking adjustment)
To move the pickup slightly.
(Correct so that the objective lens is in the neutral position)
Therefore, there is no need to adjust the tracking of the objective lens.
No.

[0053]

[0054]

[0055]

[0056]

[0057]

[0058]

[0059]

[0060]

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of a disk drive device according to the present invention.

FIG. 2 is an explanatory diagram showing a configuration of the stepping motor of FIG.

FIG. 3 is an explanatory diagram showing a drive control signal and a drive signal of the stepping motor of FIG. 2;

FIG. 4 is an explanatory diagram showing an exciting direction of an exciting coil of the stepping motor of FIG. 1;

FIG. 5 is an explanatory diagram showing a speed when the optical pickup seeks to a target track.

FIG. 6 is a flowchart for explaining an operation at the time of seeking in FIG. 5;

FIG. 7 is an explanatory diagram showing an operation when the optical pickup moves minutely.

FIG. 8 is an explanatory diagram showing a moving torque when the optical pickup moves minutely.

9 (a) and 9 (b) show the detailed operation of the part A in FIG. 8,
(a) is a steady-state deviation integrated value-time characteristic diagram, and (b) is a stepping motor drive current-time characteristic diagram.

[Explanation of symbols]

 Reference Signs List 11 tracking signal integration circuit 12 microprocessor (MCU) 13 PWM signal integration circuit 14 driver IC 15 stepping motor (STM) 16 STM current detection circuit 21 optical pickup 22 objective lens 23 disk 24 track 151-154 excitation coil 155 rotor

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-129532 (JP, A) JP-A-5-163988 (JP, A) JP-A-63-268500 (JP, A) JP-A-2- 246057 (JP, A) JP-A-63-197074 (JP, A) JP-A-62-128078 (JP, A) JP-A-6-231554 (JP, A) Japanese Utility Model Laid-Open No. 61-65898 (JP, U) (58) Field surveyed (Int.Cl. ⁷ , DB name) H02P 8/00 G11B 7/085 G11B 21/08

Claims (2)

(57) [Claims] 1. A pickup provided with an objective lens for condensing a laser beam on a disk surface, a stepping motor for moving the pickup along a radial direction of the disk, and an exciting current or voltage applied to an exciting coil of the stepping motor. in a disk drive device and a drive means for applying, to the rotor of the stepping motor, as well as pre-grant pressurization large a static friction than the detent torque, the larger torque than pressurizing the Control means for controlling the excitation current or voltage of the stepping motor so as to act on the rotor, after the pickup is moved to the target track position,
A disk drive device, wherein the control means controls the exciting current or voltage of the stepping motor to rotate the stepping motor minutely to move the pickup minutely. 2. The method of claim 1, wherein said objective lens is tracking adjustable since and, said control means energizing of the stepping motor based on a deviation signal indicating the amount of displacement from a predetermined position of the objective lens by controlling the current or voltage, the objective lens is a disk drive apparatus according to claim Rukoto said stepping motor is small rotated by slight moving the pickup to move to a predetermined position.