JP3478585B2 - Optical disc reproducing apparatus and control method therefor - 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, and more particularly to an MCLV (Modified CLV) type optical disk reproducing apparatus and a control method thereof.

[0002]

2. Description of the Related Art Conventionally, there are various optical disk reproducing apparatuses having different disk recording methods. A well-known recording method for a disc of an optical disc reproducing device is C
LV (Constant Linear Velocity) method, CAV (Constan
t Angular Velocity) method. More recently, CL
The MCLV (Modified CLV) system is an improved system that can simplify the shift control of the spindle motor by taking advantage of the large recording capacity of the V system.

In the MCLV system, for example, as shown in FIG. 5, the entire recording area of the disc is divided into a plurality of zones each including a predetermined number of adjacent tracks, and each zone is reproduced at a constant disc rotation speed. When the recording is performed, the recording is performed so that the reproduction data rate becomes constant. Therefore, the recording linear density in each zone continuously changes as shown in the figure. Further, generally, recording is performed so that the recording linear density of the first track of each zone and the change of the recording linear density in each zone are the same between the zones.

Data recorded on a disc is divided into units called sectors. An example of the format of this sector is shown in FIG. Here, the SM (sector mark) will be described in detail. Generally, in an optical disc reproducing device, a disc reproducing signal from an optical pickup is binarized, a data clock is extracted by a PLL, and the binarized reproducing signal is sampled by the data clock. However, the SM is devised so that the SM can be identified by using, for example, a reference clock having a predetermined frequency without using the data clock from the PLL. Specifically, the mark length is made particularly long, or the data pattern is unique. Further, the SM has an SMID pattern for identifying the zone number in which the corresponding sector exists. Therefore, several kinds of code patterns are prepared for the SM. For example, SM that is different for each zone
A code pattern may be prepared or some SM code patterns may be cyclically assigned to each zone. In the latter case, for example, two types of SMID code patterns (SMID0, SMID1) are prepared and SMID0 is set in the 0th zone.
SMID1 is assigned to the first zone, SMID0 to the second zone, SMID1 to the third zone, and so on. FIG. 7 shows an example of two types of SMID code patterns (SMID0, SMID1).

When reproducing a disc recorded by the MCLV system, the system for setting the number of revolutions of the disc can be roughly classified into two systems. The first method is a method in which a constant number of rotations is given to all zones in the disc, and the second method is a method in which a predetermined number of rotations is given to each zone so that the reproduction data rates of all the zones are equal. Is. In the first method, the reproduction data rate is constant in each zone, but the reproduction data rate is higher in the outer periphery of the disc because the reproduction data rate differs between zones. FIG. 8 shows the relationship between the disc rotation speed and the reproduction data rate in the above two methods. In general, it is desirable that the processing speed of the signal processing unit does not change in the optical disk reproducing apparatus, and the second disk rotation speed setting method is often used.

Further, the disc rotation control system in the optical disc reproducing apparatus can be roughly classified into two systems. The first method is shown in FIG. In the figure, a circuit for performing focus servo and tracking servo of the optical pickup is omitted. Reference numeral 1 is a spindle motor that drives an optical disk. An FG (frequency generation) device 2 is attached to the spindle motor 1. This FG device 2
Outputs a signal having a frequency proportional to the rotation speed of the spindle motor 1, and inputs the signal to the frequency measuring device 3. The frequency measurement value of the frequency measuring device 3 is input to the comparator 4. The comparator 4 compares the measured frequency value with the reference value and inputs the result to the PWM generator 5. The PWM generator 5 has a predetermined carrier frequency P based on the output of the comparator 4.
Generate a WM signal. The duty ratio of the generated PWM signal changes as follows based on the comparison result of the comparator 4. That is, if the frequency measurement value is larger than the reference value, P
If the duty ratio changes so that the low level section of the WM signal becomes longer and the reference value is greater than the frequency measurement value, P
The duty ratio changes so that the high level section of the WM signal becomes longer. The change of the duty ratio is performed with a predetermined step width every predetermined time. The generated PWM signal is LP
It is input to the F (low pass filter) 6 and the carrier component is sufficiently removed, and then input to the spindle motor 1. Incidentally, the longer the high level section of the PWM signal, the higher the voltage input to the spindle motor 1. The rotation speed of the spindle motor 1 changes in proportion to the input voltage.
Thus, in this disc rotation control method, the disc rotation speed can be set arbitrarily by arbitrarily selecting the reference value.

Next, the second method is shown in FIG. In addition,
In the figure, circuits for performing focus servo and tracking servo of the optical pickup are omitted. 17
Is an optical pickup for reading a signal recorded on the disc D. The signal read by the optical pickup 17 is input to the waveform equalizer 18 and the waveform is shaped. The waveform-shaped reproduced signal is input to the status slicer 19 and converted into a binary signal. The binarized reproduced signal is the SM detector 20.
Entered in. The SM detector 20 detects the SM in the reproduction signal and generates a detection pulse signal each time it detects the SM. SM
The SM detection pulse signal from the detector 20 is the frequency measuring device 1
3 and the frequency of the SM detection pulse signal is detected. The frequency of the SM detection pulse signal is the optical disc D.
In the same zone above, it is proportional to the disc rotation speed. The frequency measurement value obtained by the frequency measuring device 13 is input to the comparator 14. The comparator 14 compares the frequency measurement value with the reference value and inputs the result to the PWM generator 15.
The PWM generator 15 generates a PWM signal having a predetermined carrier frequency based on the output of the comparator 14. The duty ratio of the generated PWM signal changes as follows based on the comparison result of the comparator 14. That is, if the frequency measurement value is larger than the reference value, the duty ratio changes so that the low level section of the PWM signal becomes longer, and if the reference value is larger than the frequency measurement value, the high level section of the PWM signal becomes longer. The duty ratio changes so that The change of the duty ratio is performed with a predetermined step width every predetermined time. The generated PWM signal is an LPF (low pass filter) 16
Is input to the spindle motor 11 after the carrier component is sufficiently removed. Incidentally, the longer the high level section of the PWM signal, the higher the voltage input to the spindle motor 11. The rotation speed of the spindle motor 11 changes substantially in proportion to the input voltage. Thus, in this disc rotation control method, the disc rotation speed can be set arbitrarily by arbitrarily selecting the reference value, and if the reference value is at least constant regardless of the zone on the optical disc D, The disc rotation speed is automatically controlled so that the reproduction data rate is the same in the zone.

When the above two methods are compared, the second disk rotation control method is advantageous in cost. That is, the difference between the two methods is that the first method is the FG device 2
The second method is that the SM detector 20 is provided instead of the above. Since the SM detector 20 can be realized by a digital circuit, the cost can be reduced if it is integrated with other digital circuits (not shown). Compared to the FG device 2, the number is extremely small. Furthermore, it is also advantageous for downsizing the device. For these reasons, when it is desired to reduce the cost and size of the optical disc reproducing apparatus, it is desirable to adopt the second disc rotation control method. .

FIG. 11 shows the structure of an optical disk reproducing apparatus which employs the second disk rotation control method. In the figure, the same parts as those in FIG. 10 are designated by the same reference numerals.
The operation relating to the disc rotation control in this reproducing apparatus is the same as the operation of the second disc rotation control method.

In this optical disk reproducing apparatus, the reproduced signal binarized by the data slicer 19 is the SM detector 2
It is input to the PLL 21 as well as 0, and is further given to the flip-flop (hereinafter referred to as FF) 22 as a data input. The PLL 21 has a reference frequency corresponding to a predetermined reproduction data rate and generates a reproduction clock phase-locked with the input signal. The reproduced clock signal, which is the output signal from the PLL 21, is input to the FF 22 and other subsequent processing units. The FF 22 latches the input data signal at the rising edge of the input clock signal,
The sampling data is output to the subsequent processing unit. FIG. 12 shows how the reproduction signal (input signal) from the data slice 19 is sampled by the reproduction clock signal.

Next, the operation at the time of zone switching in this optical disk reproducing apparatus will be described. N in FIG.
The time change of the disk rotation speed and the reproduction data rate at the time of switching from the zone to the (n + 1) zone is shown.
During n-zone reproduction, the disc rotation speed is controlled so as to attain a predetermined reproduction data rate, and it is assumed that the disc is in a sufficiently stable state. At this point, the reproduction of the n zone is finished, and the reproduction of the (n + 1) zone is continuously started without interruption. At this point, ideally, it is desirable that the number of revolutions of the disc be instantaneously switched to the number of revolutions of the disc at which the same reproduction data rate as that at the time of n zone reproduction can be obtained. However, in practice, the disk rotation speed asymptotically changes as shown in the unstable region in the figure. Here, when the loop band of the spindle motor control circuit system is set to 10 Hz, for example, the time from the zone switching to the desired rotation speed is about 0.1 s. This time corresponds to the time required for one rotation of the disk when the disk rotation speed is 600 rpm. On the other hand, the reproduction data rate is instantaneously switched to the reproduction data rate obtained when the (n + 1) zone is reproduced at a desired disc rotation speed during n-zone reproduction at the moment when the zone is switched. After that, the reproduction data rate changes (decreases) in proportion to the asymptotic change of the disc rotation speed, and in the stable region, the reproduction data rate settles to a desired reproduction data rate during n zone reproduction. Note that the reproduction data rate change rate at the moment when the zones are switched is, for example, a maximum change rate of about 10 when the recording inner radius on the disc is 10 mm, the recording outer radius is 60 mm, and the number of zones is 20.
%. The disk rotation speed and the reproduction data rate in the second disk rotation setting method shown in FIG. 8 indicate the case where the disk rotation speed ideally changes. In such a change situation of the reproduction data rate,
In order to continuously reproduce the recorded data regardless of the zone switching, the reproduction clock extraction function of the PLL needs to follow the change in the reproduction data rate sufficiently quickly. Especially at the moment when the zone is switched, it is necessary to read in the sector format shown in FIG.
Within the interval of SM and first VFO before M (address mark), the PLL must complete the phase lock pull with a maximum 10% frequency change in this example.

[0012]

As described above, in the conventional optical disc reproducing apparatus adopting the second disc rotation control method, the SM in the first sector after zone switching is changed.
In the section of the first VCO and the PLL, it is necessary for the PLL to perform the phase pull-in operation with a large change in the reproduction clock frequency. Therefore, at least the first sector after zone switching is difficult to read the recorded data correctly. There is a problem. After the zone is switched, in the transient state until the desired disk rotation speed in the zone is settled, if the PLL does not follow the change of the reproduction data rate with sufficient high-speed response performance while keeping the phase synchronization state, the recording is performed. There is a problem that the data cannot be read correctly.

These problems are not limited to the case where the data is continuously read at the time of zone switching, but also the case where the data reading is to be started from the first sector after the zone switching. This is because even if the data is read from the first sector after zone switching, tracking control and focus control are stable.
This is because it is necessary to trace from the zone before the zone as an approach run, and the changes in the reproduction data rate and the disk rotation speed are the same as in the case of continuously reading data.

The present invention is intended to solve such a problem, and provides an optical disc reproducing apparatus capable of stably and accurately reproducing a signal from a leading sector of a first track after zone switching at a predetermined reproduction data rate. It is an object.

The present invention is intended to solve such a problem, and provides an optical disk reproducing apparatus capable of stably and accurately reading recorded data from a leading sector of a first track after zone switching at a predetermined reproducing data rate. The purpose is to provide a control method.

[0016]

The optical disk reproducing apparatus of the present invention SUMMARY OF THE INVENTION To achieve the above object, the entire recording area, a plurality of zone consisting of a plurality of adjacent tracks, respectively
Reproducing and recording linear density in the individual zones are divided into over down is a continuously varying optical disk at a constant playback data rate across the zones while rotating the optical disk at a rotational speed that corresponds to each zone In the optical disc reproducing apparatus, an optical pickup for reading a recording signal of the optical disc, a clock generating means for generating a reproduction clock signal phase-synchronized with the reading signal of the optical pickup, and the optical pickup for reading the signal. Zone switching detection means for detecting zone switching, and a zone before switching after a predetermined time has elapsed since the zone switching detection means detected zone switching.
The light pickup toward the down by one track transfer, and disk rotation speed the clock frequency of the clock generating means constant and sets the speed corresponding to the next zone of the zone after the movement said optical pickup The playback data rate is fixed to a value that can be obtained , and the zone is switched.
And a control means for performing control so as to release the fixed clock frequency of the clock generation means when the detection means detects again the zone switching. In order control method of the optical disc reproducing apparatus of the present invention to achieve the above object, the entire recording area, composed of a plurality of adjacent tracks each double
An optical disc that is divided into several zones and in which the recording linear density changes continuously within each zone
An optical disk reproducing apparatus for reproducing at a constant playback data rate across the zones while rotating the optical disc in rotation number, a playback synchronized in phase with Re signal or Rako read by the optical pickup from the optical disk In the control method of the optical disc reproducing apparatus, the control method for the optical disk reproducing apparatus comprises the clock generation means for generating the clock signal of 1) and the zone switching detection means for detecting the switching of the zone where the signal is read by the optical pickup. Is switched after a predetermined time has passed since the
The optical pickup is moved one track toward the previous zone, the disc rotation speed is switched to the rotation speed corresponding to the zone next to the zone after the movement of the optical pickup, and the clock frequency of the clock generation means is set to the above-mentioned value. Fixed to a value that gives a constant playback data rate ,
When Switching Operation instead of zone has been detected again by the serial zone switching detection means, characterized in that you unpin a clock frequency of the clock generating means.

[0017]

That is, in the optical disc reproducing apparatus and the control method thereof according to the present invention, after a predetermined time has elapsed after the zone switching was detected, the zone is moved toward the zone before the switching.
Serial light is picked up by one track moves, the clock frequency of the clock generating means a constant playback data rate obtained with setting the disk rotation speed to a speed corresponding to the next zone of the zone after the optical pick-up moving at the same time the value Fixed to. And then when the zone-change of is detected again, by performing control to release the fixation of the clock frequency of the clock generator from the reproduction start time of the first track after switching zone, after switching zone Thus, the desired disk rotation speed can be obtained, and the recording signal can be correctly reproduced from the head sector of the first track at the predetermined reproduction data rate.

[0018]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 is a diagram showing the configuration of an optical disk reproducing apparatus according to an embodiment of the present invention. In the figure, D is an optical disc, and 41 is an optical pickup for reading information from the optical disc D. The read signal of the optical pickup 41 is input to the waveform equalizer 42, the focus servo unit 43, and the tracking servo unit 44. Focus servo unit 4
Reference numeral 3 detects a focus error signal from the input signal, performs a predetermined signal processing, generates a focus control signal, and inputs the focus control signal to the optical pickup 41. The optical pickup 41 is focus-controlled by this focus control signal. The tracking servo unit 44 detects a tracking error signal from the input signal, performs a predetermined signal processing, generates a tracking control signal, and inputs the tracking control signal to the optical pickup 41. The optical pickup 41 is tracking-controlled by this tracking control signal.

The tracking servo unit 44 includes a control unit 45.
A track jump pulse is input from. When the tracking servo section 44 receives the track jump pulse, it generates a tracking control signal for performing a track jump for one track, and inputs the tracking control signal to the optical pickup 41. When the optical pickup 41 inputs the tracking control signal generated to perform the track jump,
Perform track jumps for the number of tracks. In this example, the track jump is performed in the inner circumferential direction of the disc.

The waveform equalizer 42 shapes the waveform of the input signal for the purpose of removing intersymbol interference. The waveform-shaped reproduced signal is input to the data slicer 46 and converted into a binary signal. The binarized reproduction signal is input to the SM (sector mark) detector 47 and the switch SW2. One input of the switch SW2 is a fixed signal of "L" level.
The switch SW2 is switched by a SW control signal output from the control unit 45. In switch SW2, S
When the W control signal is at "H" level, the data slicer 46
Is selected, and when the SW control signal is at "L" level, a fixed signal at "L" level is selected. The selection signal of the switch SW2 is given to the PLL 48 and the flip-flop (hereinafter referred to as FF) 49 as a data input.

The PLL 48 has a reference frequency corresponding to a predetermined reproduction data rate and generates a signal reproduction clock that is phase-synchronized with the input signal. The reproduced clock signal output from the PLL 48 is input to the FF 49 and other post-stage processing units. The FF 49 latches the input data signal at the rising edge of the input clock signal and outputs it as sampling data to a processing unit (not shown) in the subsequent stage. Further, the PLL 48 is in a free-running state when the input signal is a fixed signal of "L" level (may be "H" level), and the free-running frequency at that time becomes equal to a predetermined reproduction data rate. Well tuned.

The SM detector 47 detects the SM (sector mark) in the reproduced signal and generates a detection pulse signal each time it detects the SM (sector mark). This SM detection pulse signal is used by the frequency measuring device 50.
Entered in. Further, the SM detector 47 detects the SM ID and inputs the detected ID signal to the control unit 45. The frequency measuring device 50 detects the frequency of the SM detection pulse signal from the input SM detection pulse signal. The frequency of the SM detection pulse signal is proportional to the disk rotation speed within the same zone on the optical disk D. The frequency measurement value obtained by the frequency measuring device 50 is input to the comparator 51. Further, either the reference value A or the reference value B is selectively input to the comparator 51 via the switch SW1. Comparator 51
Then, the magnitude comparison between the frequency measurement value and the reference value is performed, and the result is input to the PWM generator 52. The PWM generator 52 generates a PWM signal having a predetermined carrier frequency. The duty ratio of the generated PWM signal changes as follows according to the magnitude comparison result. If the frequency measurement value is larger than the reference value, the duty ratio changes so that the low level section of the PWM signal becomes longer, and if the reference value is larger than the frequency measurement value, the high level of the PWM signal. The duty ratio changes so that the section becomes longer. The change of the duty ratio is performed with a predetermined step width every predetermined time. The generated PWM signal is input to the LPF (low pass filter) 53, and after the carrier component is sufficiently removed, it is input to the spindle motor 54.
Incidentally, the longer the high level section of the PWM signal, the higher the voltage input to the spindle motor 54. The rotation speed of the spindle motor 54 changes almost in proportion to the input voltage.

The switch SW1 is switched by the SW control signal output from the control section 45 as follows. S
When the W control signal is at "H" level, the reference value A is selected,
When the SW control signal is at "L" level, the reference value B is selected. Here, the reference value A is a comparison reference value that gives a disc rotation speed such that a predetermined reproduction data rate can be obtained by reproduction in each zone. The reference value B is a comparison reference value that gives a disk rotation speed at which a predetermined reproduction data rate is obtained, assuming that the disk rotation speed at the time of reproducing n zones is (n + 1) zone reproduction. .

The reference value A and the reference value B will be further described. When the number of sectors per track in the n zone is N _SM (n) and the disk rotation speed at which a predetermined reproduction data rate is ω (n) in the n zone, the disk is recorded so as to satisfy the following expression 2-1. To be done.

Ω (n) · N _SM (n) = ω (n + 1) · N _SM (n + 1) ... Equation 2-1 In this case, the reference values A and B are the reference values A = ω (n) · N. _SM (n) ... Equation 2-2 Reference value B = ω (n + 1) · N _SM (n) ... Equation 2-3.

When the control section 45 detects from the SMID detection signal input from the SM detector 47 that the disc reproduction position has been switched from the n zone to the (n + 1) zone, a track kick pulse is generated after a predetermined time. . Further, when it is detected that the disc reproduction position is switched from the (n + 1) zone to the n zone after the generation of the track kick pulse, the SW control signal is set to the “L” level and the reference value is switched from A to B. Further, after that, when it is detected that the disc reproduction position is switched from the n zone to the (n + 1) zone, the SW control signal is set to the “H” level and the reference value is returned to A.

Next, the temporal operation in this embodiment will be described. FIG. 2 shows a scanning locus of the optical pickup 41 on the disk surface as an operation example. Optical pickup 4
1 sequentially shifts from time position 1 to 7 . Here, time positions 1 to 2 are located on the last track in the n zone. Time position 2 is located at the switching point between the n zone and the (n + 1) zone. Time positions 2 to 3 are (n
+1) Located on the first track in the zone. In addition,
Immediately before the time position 3 , the optical pickup shifts from the first track in the (n + 1) zone to the final track in the n zone by the track jump operation. Time position 3 is located on the last track of the n zone. Time positions 3 to 4 and 5 are located on the last track in the n zone, at which time position 5 switches from the n zone to the (n + 1) zone. Time positions 5 to 6 and 7 are located on the first track in the (n + 1) zone.

FIG. 3 shows changes in the disc rotation speed, the reproduction data rate, the track kick pulse, the SW control signal for selecting the reference value, the reproduction clock frequency, and the PLL synchronization state in accordance with the time position series 1 to 7 .

At time positions 1 to 7 , the disk rotation speed ω (n) is a rotation speed satisfying the expression 2-4, and ω (n) = reference value A / N _SM (n) ... Expression 2 -4 The reproduction data rate is a predetermined reproduction data rate obtained from the disc rotation speed. Further, the SW control signal is at "H" level, the reproduction clock frequency is the frequency that matches the reproduction data rate, and the PLL 48 is in the synchronous state. That is, the time positions 1 to 7 are in a state where data is correctly reproduced in the n zone at a predetermined reproduction data rate.

Next, at time positions 2 to 3 , the SW control signal is at the "H" level, and the disk rotation speed is the reference value A.
Is controlled as a control comparison value, the disk rotation speed ω
(N + 1) is asymptotically controlled to a rotation speed that satisfies Expression 2-5.

Ω (n + 1) = reference value A / N _SM (n) ...
(Equation 2-5) As a result, the reproduction data rate is instantaneously increased at the time position 2 , and asymptotically approaches the predetermined reproduction data rate following the change in the disc rotation speed. The PLL 48 tries to show a movement that follows the reproduction data rate, but is not in the phase locked state. Here, a track kick pulse is generated after a predetermined time has elapsed from the time position 2 . As a result, the optical pickup 41 causes a track jump and shifts to the time position 3 . Therefore, the data cannot be correctly reproduced in this time position section.

Next, at time positions 3 to 4 and 5 ,
The SW control signal becomes "L" level. As a result, the disk rotation speed is controlled using the reference value B as the control comparison value, so that the disk rotation speed is asymptotically controlled to a rotation speed that satisfies Expression 2-6.

Ω (n + 1) = reference value B / N _SM (n) ...
...... Equation 2-6 In this case, the control target disk rotation speed is from time position 2 to 3
Since it is the same as that at, the change in the disc rotation speed is continuous and asymptotic from before the time position 3 , and stabilizes at the desired rotation speed at least by the time position 5 . The reproduction data rate instantaneously changes to an undesired value at time position 3 . This value is the reproduction data rate when the n zone is reproduced at the disc rotation speed of ω (n + 1).

In the period from time positions 3 to 4 and 5 , the SW control signal from the control unit 45 to the switch SW2 is set to the "L" level. This allows PLL48
The input signal to is fixed to the "L" level, and the PLL 48 is in the free-running state assuming that there is no input signal. Where P
If the free-running frequency of the LL 48 is adjusted to be sufficiently close to the predetermined reproduction data rate, the reproduction clock frequency will be almost the predetermined reproduction data rate.

Furthermore, in order to positively control the reproduction clock frequency in this state, the following PLL 48 with AFC (automatic frequency control) is used in this embodiment.

FIG. 4 is a diagram showing the structure of the PLL 48 with AFC. In the figure, the input signal is the phase comparator 61.
Entered in. The phase comparator 61 further inputs the output signal of the VCO (voltage controlled oscillator) 62, that is, the reproduction clock, and compares the phases of both signals. The phase comparison error signal from the phase comparator 61 is input to the voltage adder 63. Further, the voltage adder 63 inputs the output signal from the frequency control voltage generator 64 and adds the voltages of both signals. Voltage adder 6
The output signal of No. 3 is input to the loop filter 65, added with a predetermined frequency characteristic, and input to the VCO 62. VC
O62 outputs a signal having a frequency proportional to the voltage of the input signal as a reproduction clock. Further, the reproduced clock is input to the frequency detector 66 and its frequency is measured. The frequency measurement result is input to the comparator 67. Further, the comparator 67 inputs the frequency reference value, compares the values of both signals, and inputs the comparison result to the frequency control voltage generator 64. The frequency control voltage generator 64 generates a voltage based on the comparison result of the comparator 67. That is, in the comparison result, when the frequency reference value is higher than the measurement frequency, a voltage is generated so that the frequency of the reproduction clock is lower, and when the frequency reference value is lower than the measurement frequency, the frequency of the reproduction clock is high. To generate a voltage such that As a result, the phase of the reproduced clock is controlled based on the error signal of the phase comparator 61, and the frequency control voltage generator 64
The frequency control of the reproduction clock is performed based on the output signal of. The frequency reference value is given a value equivalent to the desired reproduction data rate. Of course, this section is not in the phase synchronization state and the data cannot be correctly reproduced.

Next, at time positions 5 to 6 and 7 , S
The W control signal becomes "H" level. As a result, the disk rotation speed is controlled using the reference value A as the control comparison value, so that the disk rotation speed is controlled to the rotation speed that satisfies Expression 2-7.

Ω (n + 1) = reference value A / N _SM (n +
1) ... Equation 2-7 In this case, the control target disk rotation speed is from time position 2 to 5
From time position 5 (n +
1) A desired disk rotation speed in the zone can be obtained. It recovered clock frequency also in the time position 5 is maintained substantially the value predetermined reproduced data rate is obtained by the free-running state of the PLL48 from time position 5 previously. Therefore, the reproduction data rate instantly changes to the predetermined reproduction data rate at the time position 5 . Further, from the time position 5, S from the control unit 45 to the switch SW2
The W control signal is switched to the “H” level, and the reproduction signal from the data slicer 46 is input to the PLL 48. Therefore, after the time position 5, after a predetermined phase pull-in time elapses, a reproduction clock signal phase-synchronized with the reproduction signal is generated. Here, if the phase pull-in time is equal to or less than the SM (sector mark) on the sector format and the VFO section time, necessary data can be correctly reproduced after the time position 5 .

Thus, according to the optical disk reproducing apparatus of the present embodiment, the desired disk rotational speed in the zone after switching is started from the reproduction start time of the first track after zone switching without depending on the high-speed response performance of the PLL 48. It is possible to read the recorded data stably and accurately from the first sector of the first track at the predetermined reproduction data rate.

[0041]

As described above, according to the optical disk reproducing apparatus and the control method thereof of the present invention, the desired disk rotational speed in the zone after switching can be obtained from the reproduction start time of the first track after zone switching. The recording signal can be stably and accurately reproduced from the head sector of the first track at a predetermined reproduction data rate.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an optical disk reproducing device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a scanning locus of an optical pickup on a disc surface of the optical disc reproducing apparatus of FIG.

FIG. 3 is a diagram illustrating a disk rotation speed, a reproduction data rate, a track kick pulse, a SW control signal, a reproduction clock frequency, and a PL according to a time position sequence of the optical pickup shown in FIG.
It is a figure which shows the change of L synchronization state.

FIG. 4 is a block diagram showing a configuration of a PLL with AFC.

FIG. 5 is a diagram for explaining a method of recording data on a disc by the MCLV method.

FIG. 6 is a diagram showing an example of a sector format in the MCLV system disc shown in FIG. 5;

7 is a diagram showing an example of two types of SMID code patterns assigned to an SM (sector mark) on the sector format shown in FIG. 6;

FIG. 8 is a diagram for explaining two types of disk rotation speed setting methods.

9 is a block diagram for explaining a first method of the two types of disk rotation control methods shown in FIG. 8. FIG.

10 is a block diagram for explaining a second method of the two types of disk rotation control methods shown in FIG.

FIG. 11 is a block diagram showing a configuration of a conventional optical disc reproducing apparatus adopting the second disc rotation control method shown in FIG.

12 is a diagram showing how a reproduction signal is sampled by a reproduction clock signal in the optical disk reproducing device shown in FIG.

13 is a diagram for explaining an operation at the time of zone switching in the optical disc reproducing apparatus shown in FIG.

[Explanation of symbols]

D ... Optical disc, 41 ... Optical pickup, 42 ... Waveform equalizer, 43 ... Focus servo section, 44 ... Tracking servo section, 45 ... Control section, 46 ... Data slicer, 47
... SM (sector mark) detectors, SW1, SW2 ... Switches, 48 ... PLL, 49 ... Flip-flops, 50 ...
Frequency measuring device, 51 ... Comparator, 52 ... PWM generator, 5
3 ... LPF (low pass filter), 54 ... Spindle motor.

─────────────────────────────────────────────────── ─── Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) G11B 20/10-20/16

Claims (2)

(57) [Claims] 1. An optical disk in which the entire recording area is divided into a plurality of zones each consisting of a plurality of adjacent tracks, and the recording linear density continuously changes in each zone,
In an optical disc reproducing apparatus for reproducing the optical disc at a constant reproduction data rate over each zone while rotating the optical disc at a rotation speed corresponding to each zone, an optical pickup for reading a recording signal of the optical disc, and a read signal from the optical pickup Clock generation means for generating a reproduction clock signal phase-synchronized with this, zone switching detection means for detecting the switching of the zone in which the signal is read by the optical pickup, and zone switching detection means for detecting the zone switching. after a predetermined time has passed since, toward switching Operation instead in the previous zone by one track moving the optical pickup, and to set the disk rotation speed to a speed corresponding to the next zone of the zone after the movement said optical pickup Together with the clock frequency of the clock generation means Fixed to a value that gives a constant playback data rate , the zone switching detection
An optical disk reproducing apparatus comprising: a control unit that performs control so as to release the fixing of the clock frequency of the clock generation unit when the zone switching is detected again by the step . 2. An optical disk in which the entire recording area is divided into a plurality of zones each composed of a plurality of adjacent tracks, and the recording linear density continuously changes within each zone.
An optical disk reproducing apparatus for reproducing at a constant playback data rate across while rotating the optical disk at a different rotational speed for each zone in each zone, synchronized in phase with Re signal or Rako read by the optical pickup from the optical disk A method of controlling an optical disk reproducing apparatus, comprising: a clock generation unit that generates a clock signal for reproduction; and a zone switching detection unit that detects a switching of a zone in which a signal is read by the optical pickup, wherein the zone switching detection unit controls the zone. after the toggle elapse of a predetermined time from the detection of, toward the switching Operation instead in the previous zone by one track moving the optical pickup, and the corresponding rotational speed of the disk to the next zone of the zone after the movement said optical pickup Clock frequency of the clock generation means while switching to rotation speed Is fixed to a value at which the constant reproduction data rate is obtained , and the zone switching detection is performed.
When a zone switching of is detected again by means, unlock the clock frequency of the clock generating means
Control method for an optical disk reproducing apparatus, wherein the this.