JP3954259B2 - Disc player - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical disk reproducing apparatus for reproducing an optical disk such as a CD or a DVD, and more particularly to setting of a slice level of an RF signal when an optical pickup performs a track jump.
[0002]
[Prior art]
Conventionally, an optical disk reproducing apparatus for reproducing an optical disk such as a CD / DVD (hereinafter simply referred to as a disk) is based on the CLV control method (constant linear velocity). It is recorded.
[0003]
Therefore, the disc motor control method in the CD / DVD playback device is the CLV control method, and the disc rotation speed is changed between the inner and outer peripheral portions of the disc so that there is no difference in the data playback rate. I have control.
[0004]
Here, as a method of causing the PLL to follow the track jump when the optical pickup (hereinafter simply referred to as the pickup) jumps the track on the disk, the frequency information is extracted from the data signal (RF signal) during the track jump and the PLL is made to follow. There is a way.
[0005]
This method uses a slice level generation circuit to set a certain slice level only during track jumps regardless of the number of tracks to jump, and a data signal when crossing tracks at that slice level (data information on track) In addition, the frequency information of the data signal (off-track data information) detected when passing between tracks is not detected, so that the number of revolutions of the disk during track jumping is not detected. Control is performed so that the PLL does not change significantly with respect to the change of.
[0006]
However, in recent optical disk (CD / DVD) playback apparatuses, the CAV control system (constant rotation speed) is the mainstream as a disk motor control system, and has a configuration as shown in FIG. 3, for example.
[0007]
In FIG. 3, the pickup 1 reads the data recorded on the track on the disk 11 that is constantly rotated by the spindle motor 12 and outputs it to the head amplifier 2. The head amplifier 2 amplifies input data, extracts an RF signal, and outputs it to a comparator (RF signal slicer) 3 via a coupling capacitor C.
[0008]
The comparator 3 compares the input RF signal with the slice level supplied from the integration slice level generation circuit 4 or the specific slice level generation circuit 5, and binarizes it to obtain an EFM signal (digital RF signal).
[0009]
During normal playback, the slice level generated from the integration slice level generation circuit 4 is supplied to the comparator 3, but at the time of track jump, the slice level generated from the specific slice level generation circuit 5 is supplied to the comparator 3, and the switch 6 Switching is done with.
[0010]
During the track jump, the specific slice level generation circuit 5 is selected by the switch 6, and the data signal (on-track information) when crossing the track is sliced at the slice level set by the specific slice level generation circuit 5. The frequency information during the jump can be detected, and the PLL circuit 7 is made to follow based on the frequency information to facilitate the pull-in operation of the PLL after the jump is completed. The integration slice level generation circuit 4 detects the difference in time integration between the high level and low level periods of the EFM signal, and sets the slice level so that the comparator 3 always slices at the center of the RF signal.
[0011]
The PLL circuit 7 generates a bit clock for synchronizing with the EFM signal, and operates without control so that the bit clock is synchronized with the EFM signal. Since the bit clock and the EFM signal are completely synchronized, the reproduction data is stably read out.
[0012]
[Problems to be solved by the invention]
The conventional optical disc reproducing apparatus as described above adopts the CAV control method. However, when the rotation speed is the same, since the disc data is recorded by the CLV control method, the rate of the recording data at the inner peripheral portion and the outer peripheral portion. Will be different.
[0013]
Therefore, in the CAV control method, when the pickup 1 jumps the number of short (small) tracks on the disk 11, the data rate before and after the jump changes. However, since the amount of change is small, the change in the oscillation frequency of the VCO in the PLL circuit 7 is slight, so that the pull-in operation of the PLL circuit 7 at the end of the jump is not greatly affected and the pull-in operation time is not required.
[0014]
However, when jumping to a certain number of long (many) tracks, the amount of change in the data rate before and after the jump is large, so the data signal when crossing tracks according to the prior art (data information on track) With the frequency information alone, the PLL circuit 7 cannot sufficiently follow, and there is a problem that it takes time to pull in the PLL after the end of the jump.
[0015]
The present invention has been made in order to solve the above-described conventional problems. The object of the present invention is to adopt a CAV control method, even if the pickup jumps to a certain number of long (many) tracks on the disk. Another object of the present invention is to provide an optical disc reproducing apparatus that can perform the tracking of the PLL circuit satisfactorily and can perform the pull-in of the PLL after the jump is completed.
[0016]
[Means for Solving the Problems]
In order to achieve the above object, the invention of claim 1 is characterized in that pick-up means for reading data from a track on a disk rotating at a constant rotational speed, and binarizing the read data at a certain slice level to generate an RF signal. means for generating, provided a PLL circuit for multiplying the synchronized with the RF signal, the slice level used when the pickup is track jump, and a slice level setting unit is changed according to the number of tracks to jump, the slice The level setting means sets the slice level so that only on-track data can be detected when the number of tracks to be jumped is small, and can detect off-track data in addition to on-track data when the number of tracks to be jumped is large. Is to set the slice level .
[0017]
According to the first aspect of the present invention, when the slice level to be set is changed in accordance with the number of tracks to be jumped, the amount of information detected when jumping many tracks can be increased. The amount of frequency information transmitted to the circuit can be increased, and the oscillation frequency of the VCO in the PLL circuit can be changed to control the frequency as close as possible to the data rate at the arrival point after the end of the track jump.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a configuration according to an embodiment of an optical disk reproducing apparatus of the present invention. However, the same parts as those in the conventional example will be described with the same reference numerals. An optical disk reproducing apparatus has an optical pickup (pickup) 1 that reads recorded data from a disk such as a CD or a DVD, a head amplifier 2 that amplifies the data read by the pickup 1 and extracts an RF signal 100, and a binary RF signal 100. The EFM signal 200 to be converted into an EFM signal 200, the integration slice level generating circuit 4 for generating a slice level 30 for determining the binarization level of the comparator 3 based on the EFM signal 200, and the binarization level of the comparator 3 at the time of track jump. A specific slice level generation circuit 5 that generates slice level signals 501 and 502 to be determined, a switch 6 that switches between the integration slice level generation circuit 4 and the specific slice level generation circuit 5, and a PLL that generates a bit clock 80 for stably reading reproduction data. Circuit 7, head Coupling capacitor C which connects the amplifier 2 and the comparator 3, and a variable resistor VR for adjusting the level of RF signal 100 that is input to the comparator 3.
[0020]
Here, the specific slice level generation circuit 5 includes a circuit 51 that generates a slice level for a short track jump, a circuit 52 that generates a slice level for a long track jump, and a switch 8 that switches between the circuits 51 and 52. Yes.
[0021]
Next, the operation of this embodiment will be described. The pickup 1 reads data recorded on a track on the disk 11 that is rotated by a spindle motor 12 and outputs it to the head amplifier 2. The head amplifier 2 amplifies the input data and extracts the RF signal 100 and outputs it to the comparator (RF signal slicer) 3 through the coupling capacitor C. The RF signal 100 is a data signal recorded on the disc.
[0022]
The comparator 3 binarizes the RF signal 100 using the slice level 30 generated by the integration slice level generation circuit 4 or the slice level 501 or 502 generated by the specific slice level generation circuit 5, and outputs it as an EFM signal 200. . Here, the integration slice level generation circuit 4 detects the time integration difference between the high level period and the low level period of the EFM signal, and sets the slice level so that the comparator 3 always slices at the center of the RF signal 200. Circuit. On the other hand, the specific slice level generation circuit 5 is a circuit that can set the slice level to a specific level from the outside. The specific slice level generation circuit 5 is used at the time of track jumping and is switched by a switch 6 controlled by a control circuit (such as a microcomputer) not shown.
[0023]
The PLL circuit 7 generates a bit clock 80 for synchronizing with the EFM signal 200 and operates without control so that the bit clock 80 is synchronized with the EFM signal 200. Since the bit clock 80 and the EFM signal 200 are completely synchronized, the reproduction data is stably read out.
[0024]
Here, during the track jump, the switch 6 is switched to the terminal b and the specific slice level generation circuit 5 is selected, so that the comparator 3 is a slice set by the specific slice level generation circuit 5 as a data signal when crossing the track. The RF signal 100 is binarized by slicing at the level 501 or 502. Thereby, the PLL circuit 7 can detect the frequency information during the jump, and can follow the PLL based on the frequency information.
[0025]
In addition, the specific slice level generation circuit 5 of this example outputs a case of jumping a short (small) number of tracks and a case of jumping a somewhat long (large) number of tracks in order to improve the followability of the PLL. The slice level is changed.
[0026]
That is, when jumping a short track number, the switch 8 controlled by the control circuit described above is switched to the terminal a, and the slice level 501 as shown in FIG. 2 generated from the short track jump circuit 51 is supplied to the comparator 3. When jumping a long track number, the switch 8 switches to the terminal b and supplies the slice level 502 generated from the long track jump circuit 52 as shown in FIG.
[0027]
As a result, at the time of a short track jump, the comparator 3 slices the RF signal 100 at the slice level 501, as shown in FIG. 2, and binarizes it, so that the on-track information of the RF signal 100 (swells up and down the waveform in FIG. 2). Only the detected portion is detected and output to the PLL circuit 7. On the other hand, at the time of a long track jump, the comparator 3 slices the RF signal 100 at the slice level 502 and binarizes it as shown in FIG. 2, and therefore detects off-track information in addition to the on-track information of the RF signal 100. This is output to the PLL circuit 7.
[0028]
In such a long track jump, the PLL circuit 7 detects frequency information from the EFM signal 200 including off-track information in addition to on-track information. As a result, when jumping a long track number, the oscillation frequency of the VCO in the PLL circuit 7 must be changed greatly, but the PLL circuit 7 can use off-track information to change the oscillation frequency of the VCO. Even if the rate change amount is large, the oscillation frequency of the VCO in the PLL circuit 7 can be changed so as to control the frequency as close as possible to the data rate at the arrival point after the end of the track jump. For example, when a certain threshold value is exceeded, the slice level is switched from 501 to 502.
[0029]
According to the present embodiment, the slice level set by the specific slice level generation circuit 5 can be changed according to the number of tracks to be jumped. In particular, when the number of tracks to be jumped is large, in addition to the on-track information Since the slice level is set so that off-track information can also be detected and the oscillation frequency of the VCO in the PLL circuit 7 can be changed greatly, the frequency is controlled as close as possible to the data rate at the arrival point after the track jump is completed. Thus, the oscillation frequency of the VCO in the PLL circuit 7 can be changed. As a result, the PLL circuit 7 for generating the channel clock can quickly follow the change in the data rate during a long track jump, and the pull-in operation after the end of the jump can be accelerated.
[0030]
At the time of a short track jump, the RF signal 100 is sliced at the slice level 501 and binarized. However, since the amount of change in the data rate is small as in the prior art, the oscillation frequency of the VCO in the PLL circuit 7 is small. Needless to say, the change is slight, and the pull-in operation of the PLL circuit 7 at the end of the jump is not greatly affected, and the pull-in operation time is not required.
[0031]
【The invention's effect】
As described above in detail, according to the optical disk reproducing apparatus of the present invention, the pickup is somewhat long on the disk when the CAV control method is adopted by changing the slice level according to the number of tracks to be jumped ( Even if the number of tracks is jumped, the PLL circuit can be tracked well and the PLL can be pulled in after a jump.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration according to an embodiment of an optical disk reproducing apparatus of the present invention.
FIG. 2 is a waveform diagram for explaining the operation of the comparator shown in FIG. 1;
FIG. 3 is a block diagram showing a configuration example of a conventional optical disc playback apparatus.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Optical pick-up 2 Head amplifier 3 Comparator 4 Integration slice level generation circuit 5 Specific slice level generation circuit 6, 8 Switch 7 PLL circuit 11 Disk 12 Spindle motor 51 Short track jump circuit 52 Long track jump circuit C Coupling capacitor VR Variable resistance

Claims (1)

Pickup means for reading data from a track on a disk rotating at a fixed number of revolutions, means for binarizing the read data at a certain slice level to generate an RF signal, a PLL circuit for synchronizing the RF signal, the slice level used when the pickup is track jump, and and a slice level setting unit is changed according to the number of tracks to jump,
The slice level setting means sets the slice level so that only on-track data can be detected when the number of jumping tracks is small, and also detects off-track data in addition to on-track data when the number of jumping tracks is large. A disk reproducing apparatus characterized in that the slice level is set so as to be able to .

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