JPH07161129A - Spindle motor driving apparatus - Google Patents

Abstract

PURPOSE:To reduce a time required for a spindle motor to reach a required speed when an optical head is accessed to a target position and facilitate the high speed access. CONSTITUTION:Servo-error signals at respective addresses on an optical disc 101 are smoothed by a low-pass filter 105 and a plurality of voltage sources 8, 9, 10 and 11 whose levels are the same as the levels of the smoothed servo- error signals are provided. When an optical head is accessed to the target position, designated voltage source corresponding to the address value of the target position is selected by a system controller 108a. While the optical head is accessed, a spindle motor 107 is driven at a speed approximately equal to that required at the target position by the selected designated voltage source. With this constitution, the time required for the spindle motor 107 to reach the required speed at the target position can be reduced and the high speed access can be realized.

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 for recording information on a recording layer of an optical disk or reproducing / erasing previously recorded information by using a light spot obtained by focusing light of a semiconductor laser with a lens. The present invention relates to a spindle motor drive device.

[0002]

2. Description of the Related Art FIG. 6 is a block diagram showing a conventional spindle motor driving device. A conventional technique will be described with reference to FIG.

Reference numeral 101 in FIG. 6 is an optical disk, 10
2 is an optical head, 103 is a clock extraction circuit, 104 is an error signal generation circuit, 105 is a low-pass filter, 106 is a drive circuit, and 107 is a spindle motor.

In the spindle motor driving device constructed by these, when the light spot follows a predetermined track of the optical disc 101 to record information on the recording layer of the optical disc 101 or to reproduce / erase pre-recorded information. The operation of will be described.

In the case of a compact disc, a read-only mini disc, etc., the rotation speed of the optical disc 101 is controlled so that the linear velocity is constant with respect to the irradiation position of the light spot.
The optical head 102 reads the EFM signal from the pits formed on the recording layer of the optical disc 101.

Then, the clock extraction circuit 103 extracts the frame synchronization signal of the EFM signal from the EFM signal reproduced by the optical head 102. The extracted frame synchronization signal is input to the error signal generation circuit 104. On the other hand, a reference clock signal having the reference frequency of the frame synchronization signal is input from the system controller 108 to the error signal generation circuit 104. The error signal generation circuit 104 detects a phase difference or a frequency difference between the reference clock signal having the reference frequency of the frame synchronization signal and the extracted frame synchronization signal to generate and output a servo error signal.

The servo error signal generated by the error signal generation circuit 104 is smoothed by the low-pass filter 105, and is sent to the spindle motor 10 via the drive circuit 106.
6 is rotated at a predetermined rotation speed.

Further, when the optical head 102 is to access the target position during the reproduction of information, the clock extraction circuit 10
3, the frame sync signal cannot be extracted. for that reason,
The error signal generation circuit 104 first binarizes the reproduction signal from the optical head 102 and detects the longest period of the binarized reproduction signal. At this time, the system controller 108 outputs a reference clock signal of a predetermined cycle to the error signal generation circuit 104.

Then, the error signal generating circuit 104 generates the servo error signal so that the detected longest period becomes a predetermined reference period.

On the other hand, in an optical disk such as a rewritable mini disk, a track on the optical disk 101 has a wobbled guide groove.

Next, the operation of the spindle motor driving device when following a predetermined track on the optical disc 101 will be described.

First, the optical head 102 reads the tracking error signal. Then, the clock extraction circuit 103 binarizes the wobble signal included in the read tracking error signal and generates predetermined address data from the binarized wobble signal. The clock extraction circuit extracts a predetermined clock signal from the generated address data. At this time, the system controller 108 outputs a clock signal of a predetermined cycle to the error signal generation circuit 104.
The error signal generation circuit 104 detects a phase difference or a frequency difference between the extracted clock signal and a reference clock signal having a reference frequency of the clock signal to generate a servo error signal.

When the optical head 102 is accessed at the target position, the wobble signal is superimposed on the track cross signal in the tracking error signal read from the optical head 102. Therefore, the clock signal extraction circuit 1
03 cannot extract a predetermined clock signal.
Then, the error signal generation circuit 104 cannot generate the servo error signal based on the extracted clock signal, and the error signal generation circuit 104 outputs the reference level of the servo error signal,
The spindle motor 107 was driven by inertia.

[0014]

However, in the conventional spindle motor driving device, the optical head accesses the target position when recording information on a rewritable mini disk or reproducing / erasing previously recorded information. When doing so, the error signal generating circuit could not generate the servo error signal.

Therefore, the error signal generating circuit outputs the reference level of the servo error signal to inertially drive the spindle motor, and it takes time to pull the spindle servo to the predetermined rotation speed at the target position immediately after the access. There was a problem.

The present invention has been made in view of such a problem, and in the rewritable optical disc, the time for pulling the spindle motor to the predetermined rotation speed immediately after the end of the access to the target position is shortened and high-speed access is achieved. An object of the present invention is to provide a spindle motor driving device that enables the spindle motor driving device.

[0017]

In order to achieve the above object, a spindle motor driving device of the present invention comprises a clock extracting means for extracting a clock signal of a predetermined frequency from a reproduction signal from an optical head, and the clock extracting means. Error signal generating means for generating a servo error signal of the spindle motor by detecting a frequency difference or a phase difference between the clock signal extracted by the above and the reference clock signal, and the spindle motor according to the output level of the error signal generating means. Drive means for supplying a drive current to the optical head, level selection means for selecting a predetermined level according to the address value of the target position when accessing the optical head to the target position, and the optical head for accessing the target position. During the interval, the input signal to the driving means is switched from the output of the error signal generating means to the output of the level selecting means. And a switching means that.

Further, according to the present invention, the holding means for holding the output of the error signal generating means immediately before the optical head accesses the target position, and the difference between the address value immediately before the start of access and the address value at the target position are calculated. A calculation unit, an error increment prediction unit that predicts a level increment of the error signal generation unit at a target position by the output of the calculation unit, an output of the previous value holding unit, and an output of the error increment prediction unit are added. The level selection means has an addition means for setting the predetermined level.

Further, according to the present invention, there is provided a clock extracting means for extracting a clock signal having a predetermined frequency from a reproduction signal from the optical head, and a frequency difference or position between the clock signal extracted by the clock extracting means and the reference clock signal. An error signal generating means for detecting a phase difference to generate a servo error signal of the spindle motor, a driving means for supplying a drive current to the spindle motor according to the output level of the error signal generating means, and the optical head as a target. When the position is accessed, a calculating means for calculating an address difference between the address value immediately before the start of access and the address value of the target position, and a drive pulse generating means for generating a drive pulse having a predetermined width according to the output of the calculating means. And an adding means for adding the output of the drive pulse generating means and a predetermined level, and the optical head at the target position. While to Seth and a switching means for switching the output of said adding means an input signal to the drive means from an output of said error signal generating means.

[0020]

According to the present invention, the light spot follows the predetermined track on the optical disk, and when the information is recorded / reproduced / erased, a clock signal having a predetermined frequency is generated from the reproduction signal from the optical head. It is extracted by the clock extraction means. The error signal generating means detects a frequency difference or a phase difference between the clock signal extracted by the clock extracting means and the reference clock signal, and generates a servo error signal of the spindle motor. When the optical head accesses the target position, the level selecting means selects the output level of the error signal generating means near the target position according to the address value of the target position. Then, while the optical head is accessing the target position, the input to the drive means is switched from the output of the error signal generation means to the selection level selected by the level selection means to drive the spindle motor.

Further, according to the present invention, the holding means holds the output level of the error signal generating means immediately before the optical head accesses the target position. Further, the calculating means calculates the address difference between the address value of the access start position and the address position of the target position. The error increment prediction means predicts and outputs the increment level of the output of the error signal generation means at the access start position and the output of the error signal generation means at the target position based on the output of the calculation means. Then, the adding means adds the output of the holding means and the output of the error increment predicting means, and sets the output of the adding means as the selection level of the level selecting means.

Further, according to the present invention, the light spot follows a predetermined track on the optical disk, and when recording / reproducing / erasing information, a clock having a predetermined frequency from the reproduction signal from the optical head is used. The signal is extracted by the clock extraction means. The error signal generating means detects a frequency difference or a phase difference between the clock signal extracted by the clock extracting means and the reference clock signal, and generates a servo error signal of the spindle motor. When the optical head is made to access the target position, the calculation means calculates the difference between the address value at the access start position and the address value at the target position.
The pulse generation means generates a drive pulse having a predetermined width according to the output of the calculation means. The adding means adds the pulse generated by the pulse generating means and a predetermined level. Then, while the optical head is being accessed to the target position, the switching means switches the input to the driving means from the output of the error signal generating means to the output of the adding means to drive the spindle motor.

[0023]

EXAMPLES Examples of the present invention will be described below.

FIG. 1 is a block diagram showing the configuration of a spindle motor drive device according to the first embodiment of the present invention.
Here, a description will be given centering on newly added components to the conventional configuration shown in FIG.

In FIG. 1, 1, 2, 4, 5, 6, 7 are analog switches, 3 are inverters, 8, 9, 10, 1
Reference numeral 1 is a voltage source, and 108a is a system controller.

The spindle motor driving device of the first embodiment constructed as described above will be described with reference to the relationship diagram between the reproducing radial position and the rotational speed of the optical disk 101 in FIG.

When the light spot follows a predetermined track of the optical disc 101 to record information on the recording layer of the optical disc 101 or to reproduce / erase previously recorded information, it is generated by the error signal generating circuit 104. The spindle motor 107 is driven by the servo error signal. At that time, the spindle motor 107 rotates the optical disc 101 in a predetermined manner so that the linear velocity at the irradiation position of the light spot on the optical disc 101 becomes a constant value. FIG. 2 shows the reproduction radial position on the optical disc 101 and the optical disc 101.
And the radial position of the optical disc 101 can almost correspond to the address value on the optical disc 101.

The voltage source 8 in FIG. 1 generates a voltage level Vref1 that is substantially the same as the smoothing level of the servo error signal at the radial position R1 by the low-pass filter 105, and the voltage source 9 is a low-pass filter for the servo error signal at the radial position R2. 10
A voltage level Vref2 that is substantially the same as the smoothing level of 5 is generated. The voltage sources 10 and 11 are provided to generate the same voltage level as the smoothing level of the low-pass filter 105 at the reproduction radial position R3 and an arbitrary reproduction radial position Rn.

The signals adr1, adr2, adr3, adrn from the system controller 108a are voltage level selection signals, and all hold "LOW" when the light spot is following a predetermined track.

When the optical head 102 is to access the target position, the system controller 108a first sets the voltage level selection signals adr1, a corresponding to the target position.
"HIGH" to any of dr2, adr3, and adrn
Is output. For example, if the target position is the position of address 1 of the reproduction radial position R1, the system controller 108a
Outputs "HIGH" only to the voltage level selection signal adr1. Then, the analog switch 4 is turned “ON” to select the voltage level Vref1 of the voltage source 8. And
At the same time when the optical head 102 starts to access the target position, the system controller 108a outputs "HIGH" to the access start signal "access". Then, the access start signal holds "HIGH" until the access to the target position is completed. While the access start signal "access" is "HIGH", the analog switch 1 is "ON" and the analog switch 2 is "OFF". Then, the voltage level Vref1 of the voltage source 8 is input to the drive circuit 106 to rotate the optical disc 101 at the rotation speed N1 at the reproduction radial position R1.

Thus, the rotational speed of the optical disk 101 can be set to a predetermined rotational speed at the target position in advance while the optical head 102 is accessing the target position, and the pull-in time of the spindle servo immediately after the end of access is shortened. High-speed access can be realized.

Next, a second embodiment of the present invention will be described. FIG. 3 is a block diagram showing the configuration of a spindle motor drive device according to the second embodiment of the present invention. Here, the components different from those of the first embodiment will be mainly described.

In FIG. 3, 12 is a hold circuit and 13
Is an arithmetic circuit, 14 is an error increment prediction circuit, 15 is an adder,
108b is a system controller.

These operations will be described with reference to FIG. FIG. 4 shows the relationship between the reproduction radial position on the optical disc 101 and the rotation speed of the optical disc 101.

Here, the operation will be described for the case where the access start position of the optical head 102 is the address 3 and the target position is the address 1.

First, when the optical head 102 is accessed to the target position, the output level of the low pass filter 105 at address 3 immediately before the start of access is held by the hold circuit 12.
Hold by.

The hold of the output level of the low pass filter 105 is controlled by the signal "HOLDSTRT". This signal "HOLDSTRT" outputs "HIGH" from immediately before the start of access until the access is completed. During this period, the hold circuit 12 holds and outputs the output level of the low-pass filter 105. Immediately before the access is started, the system controller 108b outputs the address value of the address 3 which is the access start position by the signal "STRTad
r ", signal address value of target position address 1"
It is output to the arithmetic circuit 13 as "ENDadr".

The arithmetic circuit 13 outputs the signal "STRTadr".
And the value of the address input by the signal "ENDadr" is subtracted to calculate the increment .DELTA.adr of the moving address.
The calculated movement address increment Δadr is input to the error increment prediction circuit 14, and the error increment prediction circuit 14 uses the low pass filter 105 at the address 3 which is the access start position.
And the incremental level of the output of the low-pass filter 105 at the address 1 which is the target position is predicted and output. Then, the adder 15 adds the output of the low pass filter 105 at the address 3 held by the hold circuit 12 and the increment level output from the error increment prediction circuit 14.

The system controller 108b outputs "HIGH" to the signal "access" at the same time as the start of access, and holds "HIGH" until the end of access.

Then, the signal "access" changes to "HIG".
While holding "H", analog switch 1 is "O"
The N "state is set, and the analog switch 2 is set to the" OFF "state.

At this time, the output of the adder circuit 15 is input to the drive circuit 106 and the optical head 102 is moved to the reproduction radial position R1.
While the optical disc 101 is being accessed, the rotational speed of the optical disk 101 is previously rotated at the rotational speed N1 at the reproduction radial position R1.

As a result, the rotational speed of the optical disk 101 can be set to a predetermined rotational speed at the target position in advance while the optical head 102 is accessing the target position, and the pull-in time of the spindle servo immediately after the end of access is shortened. High-speed access can be realized.

Next, a third embodiment of the present invention will be described. FIG. 5 is a block diagram showing the configuration of a spindle motor drive device according to the third embodiment of the present invention. Here, the components different from those of the second embodiment will be mainly described.

In FIG. 5, 16 is a drive pulse generation circuit, 17 is a voltage source, and 108c is a system controller.

Next, these operations will be described. First, the arithmetic circuit 13 calculates the difference Δa between the address value at the access start position and the address value at the target position as in the second embodiment.
Output as dr.

The drive pulse generation circuit 16 includes an arithmetic circuit 13
A drive pulse having a predetermined width is generated according to the signal "Δadr" output by the. Then, the adder 15 adds the drive pulse having the predetermined width generated by the drive pulse generation circuit 16 and the voltage level Vref of the voltage source 17.
At this time, the voltage level Vref of the voltage source 17 is set to the reference level of the error signal generation circuit 104.

During the access, the system controller 108c changes the signal "access" to "HIG".
Output "H", and turn analog switch 1 "ON" and analog switch 2 "OFF".

At this time, the input of the drive circuit 106 is switched from the output of the low pass filter 105 to the output of the adder 15. Then, the spindle motor 106 is accelerated or decelerated by the output pulse of the drive pulse generation circuit 16 and then inertially driven, and the access is completed in a state where the rotational speed is substantially matched with the predetermined rotation speed at the target position.

As a result, the rotational speed of the optical disk 101 can be made substantially equal to the rotational speed at the target position in advance during the access, the spindle servo pull-in time immediately after the access is completed can be shortened, and high-speed access can be realized.

[0050]

As described above, according to the present invention, the spindle servo pull-in time immediately after the end of access can be shortened and high-speed access can be realized.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a spindle motor drive device according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a relationship between a reproduction radial position on the optical disc and the number of rotations of the optical disc in the first embodiment.

FIG. 3 is a block diagram showing a configuration of a spindle motor drive device according to a second embodiment of the present invention.

FIG. 4 is an explanatory view showing a relationship between a reproduction radial position on an optical disc and the number of revolutions of the optical disc in the second embodiment.

FIG. 5 is a block diagram showing a configuration of a spindle motor drive device according to a third embodiment of the present invention.

FIG. 6 is a block diagram showing a configuration of a conventional spindle motor drive device.

[Explanation of symbols]

 1, 2, 4-7 Analog switch 3 Inverter 8-11, 17 Voltage source 12 Hold circuit 13 Operation circuit 14 Error increment prediction circuit 15 Adder 16 Pulse generation circuit 108a, 108b, 108c System controller

Claims (3)

[Claims] 1. A spindle motor for rotating an optical disk at a predetermined rotation speed, an optical head for detecting a reflected light from the optical disk to obtain a reproduction signal, and a clock signal having a predetermined frequency from the reproduction signal from the optical head. A clock extracting means for extracting the clock signal, an error signal generating means for generating a servo error signal of the spindle motor by detecting a frequency difference or a phase difference between the clock signal extracted by the clock extracting means and the reference clock signal, Drive means for supplying a drive current to the spindle motor according to the output level of the error signal generating means, and a level for selecting a predetermined level according to the address value of the target position when the optical head accesses the target position While the selection means and the optical head are accessing the target position, the input signal to the drive means is set to the error. A spindle motor drive device comprising: switching means for switching the output of the signal generating means to the output of the level selecting means. 2. The level selecting means calculates a difference between a holding means for holding the output of the error signal generating means immediately before the optical head accesses the target position and a difference between the address value immediately before the start of access and the address value at the target position. Calculating means, an error increment predicting means for predicting a level increment of the error signal generating means at the target position by the output of the calculating means, an output of the previous value holding means and an output of the error increment predicting means are added. The spindle motor drive device according to claim 1, further comprising an adding means. 3. A spindle motor for rotating an optical disk at a predetermined number of revolutions, an optical head for detecting a reflected light from the optical disk to obtain a reproduction signal, and a clock signal having a predetermined frequency from the reproduction signal from the optical head. A clock extracting means for extracting the clock signal, an error signal generating means for generating a servo error signal of the spindle motor by detecting a frequency difference or a phase difference between the clock signal extracted by the clock extracting means and the reference clock signal, Driving means for supplying a drive current to the spindle motor according to the output level of the error signal generating means, and an address value between the address value immediately before the start of access and the address value of the target position when the optical head accesses the target position. Calculating means for calculating the difference, and generating a drive pulse having a predetermined width according to the output of the calculating means. Drive pulse generation means, addition means for adding the output of the drive pulse generation means and a predetermined level, and an input signal to the drive means of the error signal generation means while the optical head is accessing a target position. A spindle motor driving device, comprising: switching means for switching the output to the output of the adding means.