JP2002298497A - Disk reproducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a disk reproducing device for high-speed reproduction that can extend the service life of a motor by limiting the number of revolutions of the motor even when an inexpensive spindle motor is used. SOLUTION: A reproduction drive controller 18 uses a reference clock variable device 21 to gradually switch a reference clock for data reproduction so as to make an angular velocity from an inner circumference to an outer circumference of a disk 1 nearly constant according to a data address signal reproduced from the disk 1 at high-speed reproduction thereby reproducing data at a high-speed while changing the reproduction linear velocity. In the case of accessing an object position of the disk 1, after the device accesses the object position while the device applies drive control to the disk 1 so as to attain the constant line velocity corresponding to that at innermost circumference high-speed reproduction or below, the device increases the clock frequency of the reference clock variable device 21 to set the angular velocity suitable for that of the reproduction of the object position. In addition, the reproduction drive controller 18 applies rotation control to the disk so that the linear velocity is constant even outside the region at which the address signal indicates a prescribed address at high-speed reproduction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a compact disc (hereinafter referred to as CD) and a mini disc (hereinafter referred to as MD).
The present invention relates to a disk reproducing apparatus on the reproducing side in high-speed recording of music optical disks or magneto-optical disks in which data is written at a constant linear velocity, and particularly to a disk reproducing apparatus suitable for high-speed disk reproduction and target track access. is there.

[0002]

2. Description of the Related Art Discs such as CDs are generally recorded in a CLV (Constant Linear Velocity) system in which the linear velocity at which signals are read is constant in order to increase the recording density. For this reason, over the entire recording area of the disc,
In order to ensure a constant linear velocity, it is necessary to rotate the disk at a high speed when reproducing the inner peripheral portion having a small radius, and to rotate the disk at a low speed when reproducing the outer peripheral portion having a large radius. For this reason, when changing the signal reading position between the inner peripheral portion and the outer peripheral portion, not only does the reproducing head for reading the recording signal move in the radial direction of the disk, but also the linear velocity of the read signal with respect to the reproducing head increases. It is necessary to change the number of rotations of the disk so as to be constant.

FIG. 4 shows a configuration of a conventional disk reproducing apparatus. On the surface of a CD 1 as an example of a disk, address information (= absolute time information from the inner circumference to the outer circumference of the disk) is physically recorded as audio information and subcode information on spirally formed recording tracks. I have. The disc 1 is placed on a turntable 2 and is held from above by a clamper 3. The turntable 2 is connected to a rotating shaft 5 of a spindle motor 4 and is rotated by the spindle motor 4. The pickup 6 is driven by a traverse motor 7 on a slider 8 in a radial direction of the disk 1 to scan a recording track of the disk 1 and generate a reproduction signal Spu.

A servo controller 9 is connected to the output of the pickup 6 to amplify the reproduction signal Spu and to reproduce the reproduction signal SP.
A traverse for outputting as U and performing a focusing control operation for focusing the light beam of the pickup 6 on the signal surface of the disk and a tracking control operation for following the recording track on the signal surface of the disk and performing traverse feed. A tracking error signal is output.

[0005] The decoder 10 generates a data reproduction clock signal from the reproduction signal SPU output from the servo control device 9 and based on the data reproduction clock signal,
The reproduction signal SPU is subjected to various signal processing, and data recorded on the disc 1 is output as reproduction data to the output terminal 20.
And outputs the subcode information signal by extracting the subcode information included in the reproduction signal SPU. The subcode information includes the address information of the disk, and reproduction and access are performed based on the address information. A reproduction drive control device 18 serving as a rotation control means is connected to the decoder 10 and generates a traverse forced feed signal for instructing a traverse movement of the pickup 6, that is, a movement of the disk 1 in a radial direction, based on the subcode information. I do.

[0006] The traverse motor driver 17 is connected to the servo controller 9 and the reproduction drive controller 18, and generates a traverse motor drive signal based on the traverse follow error signal and the traverse compulsory feed signal. The traverse motor 7 is connected to a traverse motor driver 17 and moves the pickup 6 in the traverse direction.

On the disk 1, data strings are grouped and recorded in one block called a frame, and a pattern called a frame synchronization signal is continuously recorded at a fixed interval at the head of the frame.

The synchronization signal detector 11 outputs a frame synchronization signal component necessary for CLV control for rotating the disk at a constant linear speed from among the reproduction signals read from the disk 1 inside the decoder during reproduction.

At the time of access, since the traverse motor is driven without the tracking control operation, the frame synchronization signal cannot be detected, and only the bit signal, which is the clock information component recorded on the disk, is detected from the pickup. Assuming that the unit channel bit length is M, the channel bit width in the entire area of the disk is 3M to 11M due to the characteristics of the disk.
It is composed of

[0010] The pseudo sync signal detector 12 extracts 3M or 11M which is the shortest or longest pulse of the channel bit width as a pseudo sync signal as a second sync signal.
If the disk is rotated so that 3M or 11M is the same length at any position on the disk, rough CLV control can be performed without detecting the frame synchronization signal in the playback signal at the time of access. Can be.

The changeover switch 13 is a switch for selecting the pseudo synchronizing signal from the pseudo synchronizing signal detector 12 at the time of access, and selecting the frame synchronizing signal from the synchronizing signal detector 11 at the time of reproduction. Selects either a pseudo sync signal or a frame sync signal in response to a control command from

The reference clock generator 14 has a predetermined frequency and outputs a reference clock signal that determines the linear velocity of the disk. Both the frame synchronization signal or the pseudo synchronization signal extracted from the reproduction signal SUP and the preset reference clock signal are input to the CLV error detector 15. CL
The V error detector 15 compares the frequencies of the two clock signals, finds the difference between the clocks, and outputs a CLV error signal. The spindle motor driver 16 has a C
It is connected to the output of the LV error detector 15 and generates a spindle motor drive signal for driving the spindle motor 4 based on the CLV error signal. The spindle motor 4 is
The disk 1 is connected to a spindle motor driver 16 and is driven and controlled by a spindle motor drive signal to rotate the disk 1 at a predetermined linear velocity.

Further, a main controller 19 for controlling the entire operation of the disk reproducing apparatus is provided. The main controller 19 is provided with input means for a user to operate the disk reproducing device.

The operation of the disk reproducing apparatus thus constructed at the time of reproduction and at the time of access will be described below. At the time of reproduction, as is well known, the spindle motor 4 is rotated while performing the focusing control operation of focusing the light beam emitted from the pickup on the signal surface of the disk, and the rotation speed of the disk 1 is adjusted to the target rotation speed. To become and,
A tracking control operation for causing a light beam to follow a recording track recorded on the disk 1 is performed, and a signal reading operation from the disk 1 is started. The pickup 6 reads the signal of the disk 1, extracts a frame synchronization signal required for CLV control from the reproduced data generated in the decoder 10 by the synchronization signal detector 11, and outputs the reference clock signal of the reference clock signal by the CLV error detector 15. By comparing the frequencies and rotating the spindle motor 4 so as to eliminate the frequency difference, the linear velocity during reproduction is controlled to be constant.

Next, an access time when the read area of the disk 1 changes from the inner peripheral portion to the outer peripheral portion will be described. For example, suppose that the user suddenly operates the disc reproducing apparatus to reproduce the music track recorded on the outer peripheral portion while reproducing the music recorded on the inner peripheral portion of the disc 1. The instruction to move the reproduction area by the user is transmitted to the disk reproducing apparatus through the main controller 19 as follows.

The main controller 19 calculates the track address of the recording area corresponding to the user's designation, and inputs the calculated movement target address to the reproduction drive controller 18. The reproduction drive control device 18 compares the current address with the target address based on the subcode information, and outputs a traverse compulsory feed signal for instructing a necessary traverse movement to the traverse motor driver 17. As a result, the traverse motor 7 is driven to move the pickup 6 on the target recording track from the inner circumference to the outer circumference of the disk 1.

While the traverse motor 7 is being driven by the access, the tracking control operation is removed, and the pickup 6 outputs a signal of bit width M recorded on the disk 1 instead of the frame synchronization signal of the reproduction signal to the pseudo synchronization signal. Output to the detector 12. At the time of access, the changeover switch 13 is set to select the output of the pseudo sync signal detector 12. However, since the bit width recorded on the disk 1 is recorded between 3M and 11M, the pseudo-synchronous signal detector 12 outputs the 3M signal output from the servo controller 9.
3M or 11M, which is the shortest or longest specific period, of the signals from to 11M is detected and output as a pseudo synchronization signal at the time of access. Access switch 1
3 selects the output of the pseudo sync signal detector 12 and outputs it to the CLV error detector 15.

While the pickup 6 is moving from the inner peripheral portion to the outer peripheral portion, if the rotation speed of the disk is constant, the clock frequency of 3M or 11M, which is a pseudo synchronization signal detected at the inner peripheral portion, moves to the outer peripheral portion. As the clock frequency increases, the clock frequency increases. As a result, the clock frequency of the clock signal output from the pseudo synchronization signal detector 12 is higher than the clock frequency of the reference clock generator. That is, the value of the CLV error signal output from the CLV error detector 15 corresponding to the difference between the two clock signals increases. The spindle motor driver 16 drives the spindle motor 4 in the deceleration direction so that the value of the CLV error signal becomes small and finally the CLV error signal becomes zero.
When the value of the CLV error signal is zero, the clock frequency of the pseudo synchronization signal is equal to the clock frequency of the reference clock. This is the disk 1 of the pickup 6 at that time.
The linear velocity at the upper radial position is the reference clock generator 1
1 means that it is proportional to the reference clock signal output.

As described above, by rotating the spindle motor based on the reproduction signal of the disk 1 so that the frequency of the clock signal output from the pseudo-synchronous signal detector and the frequency of the reference clock signal coincide with each other, during access, Can make the linear velocity constant as in the case of steady reproduction without detecting a frame synchronization signal.

Now, as for the disk radius position R (m) of the pickup at the absolute time T in the subcode data, the radius of the innermost circumference of the disk is Ro, and the linear velocity of the disk at constant speed is Vo.
(M / s) = Constant and track pitch of disc is ΔR
R = (ΔR · Vo · T / π + Ro ² ) ^1/2 (1)

Further, the angular velocity ω (rad / s) of the disk at the radial position R of the pickup is expressed by ω = Vo / R (2)

Further, the rotational speed N (r
pm) is represented by N = ω · 60 / 2π (3)

From the equations (1), (2) and (3), the relationship of the rotational speed N at the absolute time T is as follows: N = Vo · 60 / 2π · (ΔR · Vo · T / π + Ro ² ) ^1/2 (4) ).

FIG. 5 shows that the linear velocity at the time of reproducing or accessing the disk is Vo = 1.2 m / sec, the track pitch ΔR = 1.6 μ, and the radius Ro of the innermost circumference of the disk is 0.0 based on the equation (4).
The curve L1 shows the relationship between the absolute time T of the disk and the absolute time of the disk during the CLV control with the absolute time T of the disk as the horizontal axis and the rotational speed N as the vertical axis in the case of 25 m. In FIG.
min = 0 minutes and Tmax = 74 minutes indicate the absolute time of the innermost circumference and the absolute time of the outermost circumference of the recording surface of the disk 1, respectively. At the time of access, the absolute time of the disk cannot be read, but by controlling the linear velocity to be constant, the rotation speed is controlled to be the same as at the time of reproduction.
Will move up.

The rotational speed at the position of the absolute time 0 minute which is the innermost circumference of the disk is N = 460 rpm, and the outermost circumference is 74.
The rotation speed at the minute position is N = 198 rpm.

[0026]

In such a disk reproducing apparatus, in recent years, a music source has been transmitted at high speed to another medium (C).
Recording from D to MD) has been developed, and a disk reproducing apparatus capable of high-speed recording has been developed. In order to record at high speed, a disk recorded at a constant linear speed can be played back at a high linear speed, but at a constant linear speed, the spindle motor must be rotated at a high speed near the inner circumference of the disk. Must.

For example, in order to reproduce at double speed, the rotational speed of the disk at the innermost circumference of the disk N = 920 rpm, and at 4 × speed, N = 1840 rpm. This is the same at the time of access regardless of reproduction. Therefore, the performance of the spindle motor may be degraded, and the life of the spindle motor is shortened. Although there is a spindle motor capable of high-speed rotation control, the cost increases.

If high-speed rotation is restricted, a frequency signal generator (FG) is directly connected to a spindle motor to rotate the disk around the inner circumference at a constant angular velocity and to rotate it around the outer circumference at a constant linear velocity. If the spindle motor is provided and the spindle motor is controlled so that its output frequency becomes constant, the angular velocity can be controlled to be constant. However, the provision of the FG increases the cost and increases the size of the apparatus.

The present invention has been made in order to solve the above problems.
Using a disk synchronization signal and address signal (absolute time signal) without using a frequency generator, the angular velocity on the inner circumference of the disk is made almost constant during reproduction, and is equal to or less than the spindle motor rotation speed during reproduction during access. It is an object of the present invention to provide a disk reproducing apparatus that suppresses high-speed rotation of a spindle motor by accessing while rotating a spindle motor at a constant linear velocity, and improves reliability with an inexpensive motor.

[0030]

According to a first aspect of the present invention, there is provided a disk reproducing apparatus according to the present invention, wherein the disk is provided from the inner circumference to the outer circumference of a disk on which data is recorded at a constant linear velocity. Rotation control means for controlling the rotation of the disk while comparing the synchronization signal reproduced from the disk with the reference clock, and switching the reference clock for data reproduction according to an address signal which is time information of data for changing the reproduction linear velocity of the disk. Reference clock switching means, wherein the rotation control means controls the reference clock switching means so that the angular velocity becomes substantially constant from the inner circumference to the outer circumference during high-speed reproduction, and gradually switches the reference clock for data reproduction. High-speed playback while controlling the rotation by the rotation control means. While rotating control disc with the reference clock switching means so as to be a constant linear velocity when the linear velocity or below the high-speed reproduction is characterized in that access to the target position.

With this configuration, at the time of high-speed reproduction, the frequency of the reference clock is gradually increased so as to gradually increase the linear velocity based on the address signal of the disk, thereby keeping the rotation speed of the disk substantially constant and keeping the linear velocity constant. The high-speed rotation of the recorded disk can be limited, and the target track can be accessed by the rotation less than the disk rotation speed at the time of high-speed reproduction without using the address signal of the disk at the time of access.

According to a second aspect of the present invention, in the high-speed reproduction, the rotation control means controls the reference clock switching means such that the angular velocity becomes substantially constant if the address signal is within a predetermined address. Then, high-speed reproduction is performed by performing rotation control for gradually switching the reference clock, and high-speed reproduction is performed while controlling the rotation so that the linear velocity becomes constant if the address signal is in a region equal to or higher than a predetermined address. .

With such a configuration, if the angular velocity is constant, the linear velocity at the outer periphery of the disk increases, and the frequency of the reproduction signal increases accordingly. Can be performed.

Further, according to a third aspect of the present invention, in the first and second aspects of the present invention, after accessing the target position,
The rotation control means controls the reference clock switching means to switch to a linear velocity at the time of high-speed reproduction of a target position.

According to this configuration, the time information in the reproduction signal cannot be detected at the time of access, so that the angular velocity cannot be controlled to be constant. After reaching the target position by keeping it below, the angular velocity is kept constant to keep it below the maximum allowable rotation speed of the spindle motor, and above a predetermined address, the rotation speed is controlled to keep the linear speed constant, so that the operating frequency of the device is suppressed. I do.

[0036]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to FIGS. Parts common to those of the conventional disk reproducing apparatus already described with reference to FIG. 4 are denoted by the same reference numerals, and detailed description is omitted.

FIG. 1 is a block diagram of a disk reproducing apparatus according to an embodiment of the present invention. FIG. 2 is a diagram showing the relationship between the absolute time and the linear velocity of the disk when the angular velocity is kept constant.
FIG. 3 is a diagram showing the relationship between the absolute time and the number of rotations of the disk during high-speed reproduction and access. Disc 1, turntable 2, clamper 3, spindle motor 4, rotating shaft 5, pickup 6, traverse motor 7, slider 8, servo controller 9, decoder 10, synchronization signal detector 11, pseudo signal in the disc reproducing apparatus of the present invention. FIG. 4 shows the synchronization signal detector 12, the changeover switch 13, the reference clock generator 14, the CLV error detector 15, the spindle motor driver 16, the traverse motor driver 17, the reproduction drive control device 18, the main control device 19, and the like. This is the same as the conventional disk reproducing apparatus.

However, in this embodiment, the operation of the reproduction drive control device 18 as the rotation control means is different from that of the conventional example as described below. The reference clock generator 14
The reference clock frequency can be varied by the reference clock changer 21 which is a newly provided reference clock switching means.

The reference clock variable unit 21 is controlled by the reproduction control drive unit 18. The reproduction drive control unit 18 obtains the position of the pickup 6 corresponding to the disk 1 from the address (absolute time) generated based on the subcode information at the time of reproduction, and sets the reference so that the rotational angular velocity of the disk 1 becomes substantially constant. A command for changing the clock frequency is given to the reference clock variable unit 21.

The reference clock variable unit 21 is constituted by, for example, a voltage controlled oscillator (VCO), and generates a target frequency in accordance with the control voltage of the reproduction drive control unit 18 based on the frequency of the reference clock generator 14. You may do so. Alternatively, a high frequency clock may be generated from the reference clock generator 14, and the frequency division ratio may be changed. Alternatively, the reference clock generator 14 and the reference clock variable device 21 may be integrated so as to generate a required clock frequency in accordance with a command from the reproduction drive control device 18.

The operation of the disk reproducing apparatus configured as described above during high-speed reproduction and access will be described using a compact disk as an example.

First, in order to vary the linear velocity and keep the angular velocity substantially constant during high-speed reproduction, it is necessary to gradually increase the linear velocity as the pickup is moved from the inner periphery to the outer periphery of the disk 1. To increase the linear velocity, the clock frequency output from the reference clock variable unit 21 should be gradually increased. By increasing the frequency of the reference clock, the clock frequency of the frame synchronization signal detected by the synchronization signal detector 11 becomes lower than the reference clock frequency. That is, the value of the CLV error signal corresponding to the difference between the two clock signals increases. Spindle motor driver 1
6 drives the spindle motor 4 in the acceleration direction so that the value of the CLV error signal becomes small and finally the CLV error signal becomes zero, and as a result, the linear velocity can be increased.

Now, the disk radius position R of the pickup at the absolute time T in the subcode data is as follows: the radius of the innermost circumference of the disk is Ro, and the linear velocity at a constant speed of the disk is Vo (m / m /
s) and the track pitch ΔR of the disk, R = (ΔR · Vo · T / π + Ro ² ) ^1/2 (1) This is the same as Expression (1) in the conventional example.

At the time of high-speed reproduction, the allowable maximum angular velocity ωmax must be kept constant in view of the performance of the spindle motor.
Assuming that the linear velocity at that time is V, ωmax = V / R = constant (5).

From the equations (1) and (5), the linear velocity V in the absolute time T at the maximum angular velocity ωmax during high-speed reproduction is as follows: V = ωmax · (ΔR · Vo · T / π + Ro ² ) ^1/2 (6) is represented by If the maximum angular velocity ωmax is determined in advance by the equation (6), the linear velocity V of the disc being reproduced at the absolute time T can be obtained.

For example, if the maximum angular velocity of the spindle motor can be allowed up to twice the innermost angular velocity at a constant speed, the innermost linear velocity is 1.2 m / s × 2 = 2.4 m / s. From equation (5), ωmax = 96 rad / s, and from equation (6), the linear velocity V with respect to the absolute time T can be obtained. FIG. 2 shows the relationship between the absolute time T and the linear velocity V when the angular velocity ωmax is constant at 96 rad / s. As shown in FIG.
By changing the reference clock frequency by the reference clock variable unit 21 so as to change as shown in FIG. 2, reproduction at a constant angular velocity becomes possible.

As described above, the absolute time is read from the reproduced signal and the frequency of the reference clock is varied by the reference clock variable unit so that the relational expression (6) holds, so that the angular velocity during reproduction is made substantially constant. Can be controlled. However, the timing of switching the reference clock by the reference clock variable unit may be changed every time the absolute time changes (13.3 ms of the frame period in the case of 1 × speed), but when the resolution of the reference clock variable unit cannot be obtained. , May be switched every few seconds (ΔT). During ΔT,
The disk rotates at a constant linear velocity.

Further, if the angular velocity during high-speed reproduction is kept constant to the outermost circumference, the linear velocity in the outer peripheral area increases, and the data transfer rate increases in proportion to the linear velocity. become unable. Therefore, claim 2
It is necessary to keep the linear velocity after a certain area being reproduced as described above. Therefore, if the data transfer speed exceeds a predetermined absolute time at which the data transfer speed reaches the maximum allowable linear speed in advance, the data transfer speed in the outermost peripheral area is set to the maximum value of the system by reproducing at a constant linear speed after the predetermined absolute time. It becomes possible to keep it below the allowable value. For example, in FIG. 2, an absolute time A for which the linear velocity exceeds the quadruple speed (4.8 m / s) is obtained in advance, and the reference clock variable unit 21 uses the reference clock variable unit 21 until the absolute time reaches A during high-speed reproduction. By gradually increasing the frequency, the angular velocity is kept constant while increasing the linear velocity. When the absolute time exceeds A minutes, the reference clock frequency is fixed, and thereafter the linear velocity is kept constant (line L in FIG. 2).
In 3), rotate the disk.

FIG. 3 is a diagram showing the relationship between the absolute time of a disk and the number of revolutions for explaining the second aspect of the present invention. In FIG. 2, the absolute time A at which the linear velocity exceeds the quadruple speed is obtained in advance, and as shown by the lines L4 and L5 in FIG. The angular velocity is controlled to be constant by moving, and when the time exceeds A, the linear velocity is made constant by moving on the line L5.

As described above, the angular velocity is maintained at a substantially constant value until the linear velocity reaches a certain value, and consideration is given to the spindle motor. If the angular velocity is exceeded, the linear velocity is maintained at a constant value and the maximum operating frequency on the system is considered. .

Next, a case where the pickup accesses the target position or the head of the target track will be described. While the traverse motor 7 is being driven by the access, the tracking control operation is removed, and the pickup 6 detects a signal of the bit width M recorded on the disk 1 as a pseudo-synchronous signal instead of a reproduction signal. This is because the time information in the reproduction signal cannot be detected during the access, so that the angular velocity cannot be controlled to be constant, and the period of the pseudo synchronization signal is 3M or 1M.
Rotate the disc to keep 1M constant,
V control will be performed. In this case, if the access is performed after setting the frequency of the reference clock so that the rotation speed at the target access position B point is reached in advance, the rotation speed of the disk from the start of the access to the completion of the access to the target position is indicated by a broken line L in FIG.
As a result, the allowable rotation speed of the spindle motor is exceeded from the inner circumference to the access position.

Therefore, at the time of access, the frequency of the reference clock is set so that the maximum allowable linear velocity at the time of reproduction of the innermost circumference is reached, and the line L7 of FIG.
By controlling the linear velocity as described above, control is performed so that the rotation speed of the spindle motor does not exceed the maximum allowable rotation speed. At the access position, since the rotation speed is lower than the target rotation speed, the frequency of the reference clock variable device 21 is increased at the access position as shown by the line L8 in FIG. Enable playback.

Thus, when the disk is reproduced or accessed at a high speed, the effect is obtained that the number of rotations of the disk and the data transfer speed can be suppressed to appropriate values.

In the above embodiment, the maximum number of revolutions of the spindle motor during high-speed reproduction is set to twice the maximum number of revolutions during constant-speed reproduction. For example, the number of rotations at the time of high-speed reproduction can be freely set.

In the above embodiment, the maximum linear velocity was set to be four times the constant velocity reproduction. However, the linear velocity during the high-speed reproduction can be freely set as long as the system of the disk reproducing apparatus is within an allowable range. Can be set.

Further, the numerical values and the like used in the description of the above-described embodiment are merely examples, and can be changed as necessary.

[0057]

As described above, according to the disk reproducing apparatus of the present invention, the rotation control means controls the reference clock switching means so that the angular velocity becomes substantially constant from the inner circumference to the outer circumference during high-speed reproduction. The data is reproduced while controlling the rotation by gradually switching the reference clock for data reproduction, and the rotation control means controls the linear velocity at the time of the innermost peripheral high-speed reproduction or the linear velocity at a lower speed or less when the target position is accessed. By accessing the target position while controlling the rotation of the disk by the reference clock switching means,
When playing or accessing the disc at high speed, the number of revolutions of the disc can be kept below the appropriate value range,
An advantageous effect is obtained in that high-speed reproduction and access at the time of high-speed reproduction can be performed using an inexpensive spindle motor with a limited number of rotations of a disk.

Further, at the time of high-speed reproduction, the rotation control means controls the reference clock switching means so that the angular velocity becomes substantially constant if the address signal is within a predetermined address, and performs rotation control for gradually switching the reference clock. If the address signal is in a region equal to or higher than a predetermined address, reproduction is performed while controlling the rotation so that the linear velocity becomes constant. An advantageous effect is obtained in that data can be reproduced without exceeding the maximum operating frequency of the system from to the outermost periphery.

[Brief description of the drawings]

FIG. 1 is a block diagram of a disk reproducing apparatus according to an embodiment of the present invention;

FIG. 2 is a diagram showing the relationship between the absolute time of a disk and the linear velocity when the angular velocity is kept constant.

FIG. 3 is a diagram showing the relationship between the absolute time and the number of rotations of a disk during high-speed playback and access.

FIG. 4 is a block diagram of a conventional disk reproducing apparatus.

FIG. 5 is a diagram showing the relationship between the absolute time and the number of rotations of a disc during constant speed reproduction.

[Explanation of symbols]

 Reference Signs List 1 disc 2 turntable 3 clamper 4 spindle motor 5 rotation axis 6 pickup 7 traverse motor 8 slider 9 servo controller 10 decoder 11 synchronization signal detector 12 pseudo synchronization signal detector 13 changeover switch 14 reference clock generator 15 CLV error detector 16 Spindle motor driver 17 Traverse motor driver 18 Reproduction drive control device 19 Main control device 20 Output terminal 21 Reference clock variable device

Claims (3)

[Claims] 1. A rotation control means for controlling rotation of a disk while comparing a synchronization signal reproduced from the disk with a reference clock from the inner circumference to the outer circumference of the disk on which data is recorded at a constant linear velocity, and Reference clock switching means for switching a reference clock for data reproduction in accordance with an address signal which is time information of data in order to change a reproduction linear velocity, wherein the rotation control means has an angular velocity substantially from the inner periphery to the outer periphery of the disk during high-speed reproduction. The reference clock switching means is controlled so as to be constant, and the reference clock for data reproduction is gradually switched to perform high-speed reproduction while controlling the rotation. The rotation control means performs the innermost peripheral high-speed reproduction when accessing the target position. The reference clock switching means so that the linear velocity at or below the linear velocity becomes constant. A disk reproducing apparatus for accessing a target position while controlling rotation of a disk. 2. A high-speed rotation control means for controlling the reference clock switching means so that the angular velocity becomes substantially constant when the address signal is within a predetermined address, and gradually switching the reference clock. 2. The disk reproducing apparatus according to claim 1, wherein the reproduction is performed at a high speed, and when the address signal is in a region equal to or higher than a predetermined address, the reproduction is performed at a high speed while controlling the rotation so that the linear velocity becomes constant. 3. The apparatus according to claim 1, wherein, after accessing the target position, the rotation control means controls the reference clock switching means to switch to a linear velocity at the time of high-speed reproduction of the target position. Disc playback device.