JP2606670B2 - Optical disc playback device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk reproducing apparatus capable of seeking an optical disk on which constant linear velocity recording has been performed in a short time by suppressing torque fluctuation of a spindle motor.

[0002]

2. Description of the Related Art Optical disks such as compact disks and laser disks can be classified into CLV (constant linear velocity) recording disks suitable for high-density recording and CAV (constant angular velocity) recording disks suitable for high-speed seek. The conventional optical disk reproducing device shown in FIG. 3 is a device for reproducing a CD (compact disk), which is a CLV recording disk, and performs a constant linear speed control on a spindle motor 2 for rotating and driving the optical disk when reading the optical disk. Therefore, the phase of the reproduced clock signal extracted from the EFM signal read from the optical disc is compared with the phase of the reference clock signal, and a required motor drive signal is transmitted to the motor driver 4 via the low-pass filter 3 so that the phase error becomes zero. It has a configuration to send. In the case of this example, the motor drive signal is output from the CD digital signal processing element 5 which can be said to be the heart of CD reproduction, and the signal read from the optical disk by the optical pickup 6 is also used for this CD. The signal is amplified by the RF amplifier circuit 7 in the digital signal processing element 5. The EFM signal amplified by the RF amplifier circuit 7 is transmitted to the digital PLL circuit 8, the frame synchronization detection circuit 9, and the EF.
The signal is sent to the M demodulator 10, but is subjected to descrambling, deinterleaving, or code error correction in the signal processing circuit 11 to which the demodulated output of the EFM demodulator 10 continues. D
It is sent to an A converter (not shown).

The digital PLL circuit 8 has a built-in voltage-controlled oscillator that oscillates according to the output of an externally mounted low-pass filter 12, and is supplied from an external crystal oscillator 14 via a clock generator 13. Reference clock signal and EF
The phase of the M signal is compared with the phase of the M signal, and the signals are synchronized with each other to generate a reproduction clock signal required for data extraction from the EFM signal. Further, the frame synchronization detection circuit 9 detects a frame synchronization signal having a predetermined bit length, and sends out a predetermined timing signal to a CLV servo circuit 15 that supplies a motor drive signal to the spindle motor 2. The signal processing circuit 11 has a built-in buffer memory for storing a fixed unit of data in association with the descrambling process and the deinterleave process, and the writing of data to this buffer memory is included in the EFM signal. While reading is performed in synchronization with the reproduced clock signal, reading from the buffer memory is performed in synchronization with the reference clock signal to absorb jitter.

[0004] A low-pass filter 3 provided before the motor driver 4 for driving the spindle motor 2 has an acceleration signal (kick pulse) and a deceleration signal (brake) for actively accelerating or decelerating the spindle motor 2 during a seek operation. pulse)
Is connected. The acceleration / deceleration means is, specifically, a microcomputer 16 for controlling the overall reproduction of the optical disk and a resistor Ra connected to a kick signal output terminal of the microcomputer 16 for injecting an acceleration signal (active "L"). And diode Da
And a forward connection circuit of a resistor Rb and a diode Db connected to a brake signal output terminal of the microcomputer 16 and injecting a deceleration signal (active "H"). By injecting the acceleration / deceleration signal into the bandpass filter 3, the rotation speed can be actively varied in inverse proportion to the track diameter when seeking the CLV recording disk.

[0005]

The above-mentioned conventional optical disk reproducing apparatus avoids fluctuations in the transfer rate during the transition period from seek to read on the seek target track when seeking a CLV recording disk on which constant velocity recording has been performed. For this reason, the rotation speed of the spindle motor 2 is changed along the contour speed curve shown in FIG. That is, for example, in the seek from the inner circumference to the outer circumference, the motor drive signal input to the low-pass filter 3 is reduced by the low active deceleration signal output from the microcomputer 16 via the resistor Rb and the diode Db, Conversely, when seeking from the outer circumference to the inner circumference, the microcomputer 16 sets the resistance R
The motor drive signal which is an input of the low-pass filter 3 is increased by the high active acceleration signal outputted via the diode a and the diode Da. For this reason, the rotational speed of the spindle motor 2 in the seek start track and the rotational speed of the spindle motor 2 in the seek target track are also inversely proportional to the track diameter, and the rotational head ΔN of the spindle motor 2 compared to both tracks is extremely large. This has also caused a large drop ΔT in the required torque of the spindle motor 2.

In general, the change in the required torque for the spindle motor 2 is not a problem for a motor having the ability to generate a large torque, but it is further reduced in size in response to demands for space saving and power reduction. There is a certain limit to responding to suddenly changing torque demands in a short time for small output torque type motors, which require a rapid increase in output torque, especially when seeking from the outer circumference to the inner circumference. Therefore, the more faithful to the basic design philosophy, such as avoiding heat generation and maintaining the mechanical life, the more effective the shortening of the access time in accordance with the high-speed movement of the optical pickup 6. Could not be expected.

On the other hand, in order to shorten the seek time by reproducing the CLV recording disk by CAV, the track kick and the buffer memory are kept while the rotation speed of the spindle motor 2 is kept at a speed close to the innermost rotation speed during the seek. An optical disk reproducing apparatus which performs the above control is disclosed in Japanese Patent Application Laid-Open No. 3-15673 / 1994 "Optical disk search apparatus". However, in 1 × speed reproduction, the rotation speed ratio of the spindle motor between the innermost circumference (diameter 25 mm) and the outermost circumference (diameter 58 mm) is 2.32 (= 58/2).
5) is not so problematic, but in the case of double-speed playback satisfying the transfer rate of 300 KB / s corresponding to MPC level II, the rotational speed ratio of the spindle motor between the innermost side and the outermost side becomes the above value. A buffer for temporarily storing reproduction data in order to maintain reproduction at the same transfer rate as at the time of apparent linear velocity reproduction irrespective of fluctuations in the transfer rate because the data reaches 4.64 which is twice as large. A memory, a write address counter that updates the input address of the buffer memory at a speed corresponding to the transfer rate, or a read address counter that updates the output address at a constant speed regardless of the transfer rate is indispensable. In order to determine the transfer rate, a sensor that detects the radial position of the optical pickup is required. Ri, the manufacturing cost there is a drawback of expensive, and the like.

[0008]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has a spindle motor for rotating and driving an optical disk recorded at a constant linear velocity, and a reproducing apparatus for reproducing data from the optical disk when reading the optical disk. A phase locked loop circuit that compares the phase of the clock signal with the reference clock signal and locks the spindle motor in a state of rotating at a constant linear speed so that the phase error becomes zero, and when the optical disk seeks, the spindle motor is driven by an acceleration signal or Acceleration / deceleration means for accelerating and decelerating in response to a deceleration signal, and a reference clock compensating means for seeking which performs frequency compensation of the reference clock signal with an acceleration signal or deceleration signal output by the acceleration / deceleration means and provides variable pitch reproduction on a seek target track It is characterized by having.

Further, according to the present invention, the seek reference clock means comprises a frequency-divided phase locked loop for dividing the reference signal, and the voltage input to the voltage controlled oscillator is controlled by an acceleration signal or a deceleration signal output from the acceleration / deceleration means. When seeking the optical disc from the inner circumference to the outer circumference, the reference clock signal is switched to a higher frequency than at the time of reading, and when seeking the optical disc from the outer circumference to the inner circumference, It is characterized in that the reference clock signal is switched to a lower frequency than at the time of reading, and the acceleration / deceleration means applies the spindle motor so as to obtain a rotation state intermediate or close to the constant linear speed and the constant angular speed. It is characterized by deceleration.

[0010]

According to the present invention, a spindle motor for rotating and driving an optical disk recorded at a constant linear speed is locked at a constant linear speed rotation state by matching the phase of a reproduction clock signal and a reference clock signal when reading an optical disk.
During an optical disk seek, while accelerating or decelerating by an acceleration signal or a deceleration signal, the reference clock signal is frequency-compensated by the acceleration signal or the deceleration signal to provide variable pitch reproduction on a seek target track, and torque fluctuation of a spindle motor during a seek is reduced. Control and shorten the access time.

[0011]

An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a circuit diagram showing an embodiment of an optical disk reproducing apparatus according to the present invention, and FIG. 2 is a diagram showing a history of a motor rotational speed at the time of seeking by the optical disk reproducing apparatus shown in FIG.

The optical disk reproducing apparatus 21 shown in FIG. 1 is provided with seek time reference clock compensating means for frequency-compensating a reference clock signal with an acceleration signal or a deceleration signal during seek, and is used for variable pitch reproduction on a seek target track. It is. The seek time reference clock compensating means shown in the embodiment is composed of a frequency dividing phase locked loop for dividing the frequency of the reference clock signal. Specifically, the clock generator 13 incorporated in the digital signal processing element 5 for CD is used.
Between the output terminal for the variable pitch PLL charge pump and the external VCO clock input terminal for the variable pitch
A series connection circuit of a low-pass filter 22 composed of a resistor R and a capacitor C and a voltage-controlled oscillator 23 is externally connected, and a connection point between the low-pass filter 22 and the voltage-controlled oscillator 23, here, a resistor R and a capacitor C Variable connection point 24
Through a microcomputer 16 which is a main part of the acceleration / deceleration means.

A variable bias circuit 24 is connected to a brake signal output terminal of the microcomputer 16 and forwardly connects a resistor Rc and a diode Dc for injecting an active "H" deceleration signal as a voltage input increase signal; A microcomputer 16 which is connected to a kick signal output terminal 16 and has a reverse connection circuit of a resistor Rd for injecting an active "L" acceleration signal as a voltage input reduction signal and a diode Dd, and is a main part of acceleration / deceleration means. Biases the voltage input of the voltage-controlled oscillator 23 according to the acceleration signal or the deceleration signal output by the controller. This bias serves to switch the reference clock signal to a lower frequency than during reading when seeking in the outer circumferential direction of the optical disk. During the seek, the acceleration / deceleration means rotates the spindle motor 2 not at a constant linear speed but at a position between or close to the constant linear speed and the constant angular speed, thereby realizing a pseudo-constant linear speed rotation.

By the way, the clock generator 13 in the CD digital signal processing element 5 has a CPU 17 in the element 5.
A switching switch 13a which is switched by a command from the controller is built in, and one of a VCO clock signal sent from an external VCO clock input terminal for variable pitch and a reference clock signal generated by the crystal oscillator 14 is selectively supplied to the digital PLL circuit 8. It is designed to be sent out. The clock generator 13 includes a frequency divider 13 b for dividing the reference clock signal from the crystal oscillator 14, a frequency divider 13 c for dividing the VCO clock signal, and both frequency dividers 13.
a phase comparator 13d for comparing the phases of the divided outputs of b and 13c and leading a phase comparison error to a variable-pitch PLL charge pump output terminal. The phase comparator 13d outputs a digital phase error signal to an analog output. A charge pump for converting to voltage is built in.

If the seek mode is selected, a seek command from the microcomputer 16 is received and the CD is received.
The CPU 17 in the digital signal processing element 5 issues a switch switching command. As a result, the VCO clock signal from the external voltage controlled oscillator 23 is sent to the digital PLL circuit 8 instead of the crystal oscillator 14, and the reference clock signal, which is the phase target of the reproduced clock signal, is frequency-compensated. Will be.

That is, during CD reproduction, constant linear velocity reproduction was performed by maintaining the rotational speed in inverse proportion to the track diameter of the reproduction track. On the other hand, as shown by the dashed line in FIG. Outer track Q
When a seek operation is performed, a high-level deceleration signal is output from the brake signal output terminal of the microcomputer 16 over a required period during the seek period. For this reason, the spindle motor 2 is decelerated to a pseudo-constant angular speed rotation state substantially intermediate between the constant angular speed and the constant linear speed. In parallel with this,
Due to the output of the bias variable circuit 24, the output of the low-pass filter 22, that is, the voltage input to the voltage controlled oscillator 23 also increases, and the oscillation frequency of the voltage controlled oscillator 23 increases. As a result, the digital PLL is replaced with the digital PLL.
Until the frequency of the external VCO clock signal supplied to the circuit 8 increases and the actual reading on the target track Q is started by the optical pitch up 6, the frequency-compensated reference clock signal is used for the phase lock for frequency division. By enabling the droop to extract a reproduction clock signal necessary for variable pitch reproduction, it is possible to maintain a data reading environment during a transitional period up to a specified constant linear velocity reproduction. In this case, the transition of the data transfer rate until the reproduction by the reference clock signal not subjected to the frequency compensation is started is also smoothly performed by changing the rotation speed of the spindle motor 2 at a pseudo-constant angular speed during the seek. A sudden change in the transfer rate can be avoided to reduce the load on the reproduction system.

On the other hand, as shown by a two-dot chain line in FIG. 2, when seeking is performed from the outer track R to the inner track S, the kick signal is output from the kick signal output terminal of the microcomputer 16 for a required period during the seek period. A low-level acceleration signal is output over this period. Therefore, the spindle motor 2
Is reduced to a pseudo-constant angular speed rotation state substantially intermediate between the constant angular speed and the constant linear speed. In parallel with this, the output of the bias variable circuit 24 also reduces the output of the low-pass filter 22, that is, the voltage input to the voltage-controlled oscillator 23, and lowers the oscillation frequency of the voltage-controlled oscillator 23. As a result, the frequency of the external VCO clock signal supplied to the digital PLL circuit 8 in place of the reference clock signal becomes small,
Until the actual reading of the target track S is started by the optical pickup 6, the frequency-compensated reference clock signal enables the extraction of the reproduction clock signal necessary for variable pitch reproduction to the frequency-divided phase locked loop. By doing so, it is possible to maintain the data reading environment in a transitional period until the reproduction at the specified linear velocity. Also in this case, the transition of the data transfer rate until the reproduction by the reference clock signal not subjected to the frequency compensation is started is smoothly performed by changing the rotation speed of the spindle motor 2 at a pseudo-conformal angular velocity during the seek. Thus, it is possible to avoid a sudden change in the transfer rate and reduce the load on the reproduction system.

At the time of double speed reproduction, the innermost circumference (diameter 25 m)
m) and the middle circumference (diameter 41.5m) between the outermost circumference (diameter 58mm)
In the seek from m) to the outermost circumference, the transfer rate is 2.79.
5 (= 2 × 58 / 41.5) times, which reduces the load on the playback diameter as compared with the transfer rate change ratio of 4.64 in the conventional method in which the innermost rotation speed is rotated to the outermost circumference at a constant angular speed. The effect is clear. In addition, with regard to the commercially available optical disc reproducing apparatus 21, an exception processing rule is provided for a seek of about several hundred tracks so that the reference clock is not changed.
The transfer rate can be made to match a preset value immediately after seeking. As described above, according to the optical disk reproducing apparatus 21, when seeking a CLV recording disk recorded at a constant linear velocity, the rotational speed of the spindle motor 2 is changed from the rotational speed at the seek start track to the rotational speed at the seek target track. In the process of changing the speed, the acceleration / deceleration means is referred to a slight acceleration or deceleration. Can be reduced. Further, the reduction of the required torque for the spindle motor 2 contributes to shortening of the access time including the moving time of the optical pickup 6, and also suppresses the heat generation due to the sudden change of the motor drive current to extend the life of the spindle motor 2. Can be planned. Also, the frequency-compensated reference clock signal enables the digital PLL circuit 8 to extract a reproduction clock signal necessary for variable-pitch reproduction before the actual reading on the seek target track is started. The data reading environment can be maintained during the transition period leading to the reproduction at the constant linear velocity.
Further, with respect to the change in the data transfer rate until the reproduction by the reference clock signal which is not subjected to the frequency compensation is started, the rotation speed of the spindle motor 2 is changed during the seek so that the reproduction is prevented from abrupt change. The burden on the system can be reduced.

Further, when the optical disk seeks from the inner circumference to the outer circumference, the acceleration / deceleration means generates a deceleration signal for reproduction on a seek target track, so that the frequency of the reference clock signal is raised to the high frequency side. Just shift to
Conversely, when seeking the optical disk from the outer side to the inner side, the acceleration / deceleration means generates an acceleration signal for reproduction on the seek target track, and the frequency of the reference clock signal is lowered. The frequency may be shifted by changing the bias voltage input to the voltage controlled oscillator 23 in the phase locked loop for frequency division for dividing the reference clock signal. Or, frequency compensation closely related to the deceleration signal is possible.

Further, the rotation speed history of the spindle motor 2 during the seek is achieved by the pseudo-constant angular speed drive with a small required torque change instead of the constant linear speed drive with a large required torque change, thereby suppressing the torque fluctuation. Can be linked to the reduction of motor load and the suppression of heat generation or the shortening of access time, etc., and the adoption of pseudo-constant angular speed drive instead of complete constant angular speed drive,
A change in the data transfer rate until the reproduction is started can be suppressed, and the load on the reproduction system can be favorably reduced.

[0021]

As described above, according to the present invention,
A spindle motor that rotates an optical disk recorded at a constant linear speed locks the spindle at a constant rotational speed by matching the phase of the reproduction clock signal and the reference clock signal when reading the optical disk, and accelerates or decelerates when seeking the optical disk. While accelerating and decelerating by the signal, the reference clock signal is frequency-compensated by the acceleration signal or the deceleration signal, and is provided for variable pitch reproduction on the seek target track. In the process of changing from the rotational speed of the seek start track to the rotational speed of the seek target track, some acceleration or deceleration is referred to the acceleration / deceleration means, but the rotational speed resembles a CLV recording disk until the seek target track is reached. Follow history In this way, torque fluctuations are suppressed as much as possible to reduce the load on the motor, and the reduction in the required torque for the spindle motor contributes to shortening the access time, including the travel time of the optical pickup, and the motor drive current. The life of the spindle motor can be extended by suppressing heat generation due to sudden changes, and the frequency-compensated reference clock signal is applied to the phase locked loop until the actual reading starts on the seek target track. On the other hand, since it is possible to extract a reproduction clock signal necessary for variable pitch reproduction, it is possible to maintain a data reading environment during a transitional period to a prescribed constant linear velocity reproduction, and to use a reference clock signal which is not subjected to frequency compensation. Changes in the data transfer rate before playback starts can be monitored during spindle seek. By changing the rotational speed, an excellent effect, such as it is possible to reduce the burden on the reproducing system to avoid abrupt changes.

Further, according to the present invention, the seek time reference clock compensating means comprises a frequency dividing phase locked loop for dividing the reference signal, and the voltage of the voltage controlled oscillator is controlled by the acceleration signal or the deceleration signal output by the acceleration / deceleration means. When the input is biased and the optical disk is sought from the inner side to the outer side, the reference clock signal is switched to a higher frequency than when reading,
When the optical disk is to be sought from the outer side to the inner side, the frequency of the reference clock signal is switched to a frequency lower than that at the time of reading. In response to issuing a deceleration signal for the purpose of reproduction on the target track, the frequency of the reference clock signal may be shifted to a higher frequency side,
Conversely, when seeking the optical disk from the outer side to the inner side, the acceleration / deceleration means generates an acceleration signal for reproduction on the seek target track, and the frequency of the reference clock signal is lowered. In order to shift the frequency by changing the bias voltage input to the voltage controlled oscillator in the phase locked loop for frequency division for dividing the reference clock signal, the acceleration signal generated by the acceleration / deceleration means or This has the effect of enabling frequency compensation closely related to the deceleration signal.

Further, according to the present invention, the acceleration / deceleration means accelerates / decelerates the spindle motor so as to obtain a rotational state intermediate or close to the constant linear velocity and the constant angular velocity. The rotation speed history is achieved by quasi-constant angular speed drive with small required torque change, not by constant linear speed drive with large required torque change, thereby reducing motor load and suppressing heat generation due to suppression of torque fluctuation or This can lead to shortening of access time, etc., and adoption of pseudo-constant-speed drive instead of complete constant-speed drive suppresses changes in the data transfer rate until playback starts, and This has the effect of reducing the burden on the user.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing an embodiment of an optical disk reproducing apparatus according to the present invention.

FIG. 2 is a diagram showing a history of a motor rotation speed at the time of a seek by the optical disc reproducing apparatus shown in FIG. 1;

FIG. 3 is a circuit diagram showing an example of a conventional optical disc reproducing apparatus.

FIG. 4 is a diagram showing a history of a motor rotation speed at the time of seeking by the optical disc reproducing apparatus shown in FIG. 3;

[Explanation of symbols]

 Reference Signs List 2 spindle motor 5 CD digital signal processing element 6 optical pickup 8 digital PLL circuit 13 clock generator 16 microcomputer 21 optical disk reproducing device 22 low-pass filter 23 voltage controlled oscillator 24 bias variable circuit

Claims (3)

(57) [Claims] 1. A phase comparison between a spindle motor for rotating an optical disc recorded at a constant linear velocity and a reproduction clock signal and a reference clock signal reproduced from the optical disc at the time of reading the optical disc. A phase locked loop circuit for locking the spindle motor to a constant linear speed rotation state, acceleration / deceleration means for accelerating or decelerating the spindle motor by an acceleration signal or a deceleration signal when the optical disk seeks, and output from the acceleration / deceleration means. An optical disk reproducing apparatus, comprising: a seek time reference clock compensating means for frequency-compensating the reference clock signal with an acceleration signal or a deceleration signal to perform variable pitch reproduction on a seek target track. 2. The seek time reference clock compensating means comprises:
A phase locked loop for frequency division for dividing the reference clock signal. The voltage input of the voltage controlled oscillator is biased by an acceleration signal or a deceleration signal output by the acceleration / deceleration means, and the optical disk is sought from the inner side to the outer side. When I do it,
The reference clock signal is switched to a frequency higher than that at the time of the read, and when seeking the optical disk from the outer peripheral side to the inner peripheral side, the reference clock signal is switched to a lower frequency than at the time of the read. Item 1
An optical disk reproducing apparatus according to claim 1. 3. The optical disk reproducing apparatus according to claim 1, wherein the acceleration / deceleration means accelerates / decelerates the spindle motor so as to obtain a rotation state intermediate or close to the constant linear velocity and the constant angular velocity. apparatus.