JPH06150346A - Method for reducing noise in disk driving device - Google Patents

Abstract

PURPOSE:To reduce an audible noise and to prevent a user from being affected by an unpleasant noise by rotating a disk for storing information, reducing the gain of focusing servo at the time of controlling the rotation of the disk or decreasing the gain at the starting time of rotation. CONSTITUTION:When musical information is reproduced or played, the gain of focusing servo is made to be an ordinary gain by opening a switch SW1 and when a control command is sent to a digital signal processor, the focusing gain is made to be grounded by closing the SW1 and the gain is decreased. Namely, the focusing servo and the tracking servo of an optical pickup 2 are turned off. Consequently, an optical disk driving device is composed of a spindle motor 1, the optical pickup 2, an objective lens 3, an actuator 4 for focusing servo, a focusing error amplifier 5, a phase compensation part 6 for focusing and the switch SW1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a noise reduction method for a disk drive device that reduces noise generated from a disk drive device that rotates a disk for recording information.

[0002]

2. Description of the Related Art A disk drive device is operated as follows. When a disc such as an optical disc is rotated by a motor of the disc driving device and, for example, information stored in the optical disc is reproduced, pressing the stop key of the disc driving device stops the rotation of the optical disc.

As a general method for stopping the rotation of the optical disk, a constant braking voltage or a constant braking voltage is applied to the spindle motor. In this case, since the rotation speed of the optical disc, the weight of the disc, and the weight of the chucking plate for chucking the disc are changed, the required braking time is changed every time.

Previously proposed disc braking methods monitor the EFM signal, for example, to check the time required for an EFM pulse width greater than 64T. This EFM signal is the conventional eight
Two-Fourteen Modulation (Eight
It is a signal obtained by a modulation method called to Fourteen Modulation. The 64T means 64 channel clocks, and a signal indicating that the EFM signal is longer than 64T is called a PW64 signal.

The constant braking voltage is applied for more than half of the time required for the EFM pulse width to detect the PW64 signal. By using this method, the optical disc can be stopped accurately for any type of optical disc and chucking plate.

[0006]

In order to monitor the EFM signal, it is necessary to activate the focus servo and the tracking servo. When the rotation of the optical disk starts to decrease, the actuator for focus servo of the optical pickup delicately operates due to the surface displacement and eccentricity of the track of the optical disk, and the actuator generates audible noise or acoustic noise. This audible noise is usually noise in the frequency range of 200 Hz to 20 kHz. The present invention has been made to solve the above problems, and an object of the present invention is to provide a noise reduction method for an optical disk drive that can reduce audible noise from an actuator.

[0007]

DISCLOSURE OF THE INVENTION According to the present invention, there is provided a disk drive for reducing a gain of a focus servo when a disk for storing information is rotated to brake the rotation of the disk. This is achieved by the noise reduction method of the device. Further, the above object can be achieved by the present invention by a noise reduction method for a disk drive device that reduces the gain of a focus servo when starting to rotate a disk for storing information.

The disk is preferably a magneto-optical disk or an optical disk.

[0009]

By reducing the gain of the focus servo, the focus servo actuator does not operate subtly even if there is surface displacement and eccentricity of the disk track, and no audible noise is produced.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described in detail below with reference to the accompanying drawings. The examples described below are preferred specific examples of the present invention, and therefore, various technically preferable limitations are given, but the scope of the present invention particularly limits the present invention in the following description. Unless otherwise stated, the present invention is not limited to these modes.

FIG. 1 shows a preferred optical disk drive for implementing the noise reduction method for a disk drive of the present invention. Spindle motor 1 of this optical disk device
Is set to disk D. This disk D is
For example, a magneto-optical disk, an optical disk, a compact disk, a CVD disk or the like can be adopted. For example, the optical pickup 2 is used to read information recorded on the disc D or record information on the disc D.

The optical pickup 2 has functions such as a focus servo and a tracking servo which have been conventionally used. That is, the optical pickup 2 is the objective lens 3
The objective lens 3 is capable of performing focus servo in the arrow U direction. From the actuator 4 for performing this focus servo, the focus error signal SFE is sent to the focus error amplifier (FE
AMP) 5.

The focus error amplifier 5 includes a variable resistor R
It is connected to the. The moving terminal 7 of the variable resistor R is connected to the focus phase compensator 6 via the resistors R1 and R2 in series. The resistor R2 is a capacitor C1 and a resistor R4.
Is connected to the resistor R5 and the switch SW1 via.
Further, the resistor R2 is connected to the resistor R6 and the resistor R6 via the resistor R3.
7 and the capacitor C2.

Next, a noise reduction method will be described. First, assume that information stored in a normal optical disc D is reproduced, for example. For example, a case of playing or playing music information will be described. During this normal play, the switch SW1 is open and the gain of the focus servo is the normal gain.

Next, the braking command is a DSP (Digital Signal Processor: Digital Signal P).
The focus servo gain, which is also called the focus gain, is sent to the switch SW.
It is grounded or grounded by closing 1.
Will decrease.

FIG. 2 is a flow chart showing a method for reducing the focus gain. Step S11
Now start braking. Next, as shown in step S12, the switch SW1 is closed to reduce the focus servo gain. Then, as shown in step S13, it is determined whether the EFM signal reaches the PW64 signal. When the PW64 signal is reached, as shown in step S14, the focus servo and the tracking servo in the optical pickup 2 of FIG. 1 are turned off.

Then, as shown in step S15, braking is further performed for 0.5 counts. The 0.5 count is half of the time required to reach the PW64 signal after the start of braking. As a result, the spindle motor 1 is turned off as shown in step S16. Then, if necessary, the routine proceeds to another routine as shown in step S17.

FIG. 2 shows a case where the focus gain is reduced particularly when the braking routine is performed. On the other hand, FIG. 3 shows only a normal braking routine. According to this routine, braking is started in step S1, and if the EFM signal reaches the PW64 signal in step S2, the focus servo and tracking servo are turned off as shown in step S3. Then, as shown in step S4, braking is performed for 0.5 counts. As a result, the spindle motor is turned off as shown in step S5.
Then, if necessary, the routine proceeds to another routine as shown in step S6.

FIG. 4 shows changes in the focus servo gain when the focus servo gain is reduced in the braking routine shown in FIG. In FIG. 4, the pulse at point B1 is a braking start pulse that indicates the time point when braking is started. Point P1 is a point when the focus servo is turned off. As a result, the drive of the focus servo is stopped.

On the other hand, FIG. 5 shows the normal braking routine of FIG. The pulse at the point P2 indicates a pulse indicating the start of braking. Point P2 is a point when the focus servo is turned off.

Comparing FIG. 4 and FIG. 5, the range Q1 in FIG.
As is clear by comparing the range Q2 in FIG. 5 with the range Q2 in FIG. 5, audible noise or acoustic noise is reduced in the range Q1 in FIG. This audible noise reduction is, for example, 200H
In the frequency range of z to 20 kHz, the focus gain is reduced by about 5.5 dB in this example.

By the way, this audible noise can be reduced by closing the switch SW1 both when the disk is started and starts to rotate and when the disk is stopped. However, the present invention is not limited to the above embodiment.

[0023]

As described above, according to the noise reduction method for the disk drive device of the present invention, the audible noise can be reduced by reducing the gain of the focus servo. Therefore, there is no fear that the user of the disk drive device will hear unpleasant noise, and a high quality disk drive device can be provided.

[Brief description of drawings]

FIG. 1 is a diagram showing a preferred embodiment for carrying out a noise reduction method for an optical disk drive according to the present invention.

FIG. 2 is a diagram showing a braking routine for carrying out a noise reduction method for an optical disk drive according to the present invention.

FIG. 3 is a diagram showing a normal braking routine in a noise reduction method for an optical disk drive according to the present invention.

FIG. 4 is a diagram showing audible noise reduction corresponding to FIG.

FIG. 5 is a diagram showing that audible noise corresponding to FIG. 3 is not reduced.

[Explanation of symbols]

 1 Spindle motor 2 Optical pickup 3 Objective lens 4 Focus servo actuator 5 Focus error amplifier 6 Focus phase compensator SW1 switch

Claims (3)

[Claims] 1. A method for reducing noise in a disk drive, wherein a focus servo gain is reduced when a disk for storing information is rotated to brake the rotation of the disk. 2. A method for reducing noise in a disk drive, wherein the gain of a focus servo is reduced when starting to rotate a disk for storing information. 3. The noise reduction method for a disk drive device according to claim 1, wherein the disk is a magneto-optical disk or an optical disk.