Dynamic information storage or retrieval – Binary pulse train information signal – Binary signal gain processing
Reexamination Certificate
1999-04-29
2001-05-22
Tran, Thang V. (Department: 2651)
Dynamic information storage or retrieval
Binary pulse train information signal
Binary signal gain processing
C369S059210, C369S124100, C369S124130, C369S053310, C369S044350
Reexamination Certificate
active
06236632
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an RF amplifier control circuit of a disk driver and, in particular, to a DVD system.
FIG. 1
shows a conventional disk driver for use as parts of an audio-video apparatus or a computer peripheral equipment.
Data is stored as a pit array on a spiral track in a disk (CD, CD-ROM, CD-R, CD-RW, DVD-ROM, DVD-RAM, DVD-Audio, DVD-Video, etc.). The reproduction, that is, the reading, of the data is effected by irradiating the pit array on a disk
11
with a laser beam and detecting a reflected laser beam from the pit array.
Upon data reproduction, the rotation speed of the disk
11
is controlled by a disk motor
13
in accordance with a data reproduction scheme. That is, upon CLV (Constant Linear Velocity) reproduction, the rotation speed of the disk is varied so as to make the rate of read data constant and, upon CAV (Constant Angular Velocity) reproduction, the rotation speed of the disk is made constant.
A laser beam is generated and detected at a pickup
12
. The laser beam detected at the pickup
12
is converted to an electric signal (pit data) and the pit data is transferred to an RF amplifier
15
. The pickup
12
is moved by a servo motor
14
and upon normal reproduction, the pickup
12
is slowly moved in a radial direction as the scanning of the laser beam is made on the track. At a time of a seek operation, the pickup
12
is rapidly moved in the radial direction of the disk
11
across the track.
An RF amplifier
15
generates a servo control signal and RF signal on the basis of the pit data. A servo control circuit
16
generates a servomotor drive signal on the basis of a servo control signal. The servomotor drive signal is supplied through a driver
17
to the servomotor
14
. A data slice circuit
18
generates digital data RFDATA on the basis of an RF signal. That is, digital data RFDATA can be obtained by detecting a DSV (Digital Sum Value) containing the RF signal and converting each component in the RF signal to a binary equivalent.
A PLL (Phase Locked Loop)•synchronous signal separating circuit
19
extracts data DATA from the digital data RFDATA, a bit clock PLCK and a synchronous signal PFCK. The data DATA and bit clock PLCK are input to an error correct circuit
20
. In the error correct circuit
20
, the correction of error data is made using a correct RAM
21
.
For the case of a DVD-video for instance, the output data of the error correct circuit
20
is input to an MPEG video decoder
22
. The MPEG video decoder
22
outputs a video signal. For the case of a DVD-ROM, the output data of the error correct circuit
20
is input to data buffer
22
and the data buffer
22
outputs the data. The data is transferred to, for example, a computer.
The bit clock PLCK is input to a frequency divider
26
. The frequency divider
26
converts the frequency of the bit clock PLCK to a ¼ (N: an integer). The output signal of the frequency divider
26
is input to the RF amplifier
15
. This feedback loop is used to obtain the characteristic (relation between the frequency and a gain) of the RF amplifier corresponding to the data rate of the read data.
A system controller
25
controls a switch circuit
27
. For the case of the CLV reproduction, a synchronous signal PFCK representing the data rate is supplied to a disk motor control circuit
24
. For the case of a CAV reproduction, a signal FG representing the rotation speed (angular velocity) is applied to the disk motor control circuit
24
. The disk motor control circuit
24
generates, based on the clock generated at a crystal oscillator and synchronous signal PFCK or signal FG, a disk motor drive signal which sets a linear velocity (for the case of the CLV reproduction) or angular velocity (for the case of the CAV reproduction) constant. The disk motor drive signal is supplied through a driver
23
to the disk motor
13
.
FIG. 2
shows one practical form of the PLL-synchronous signal separating circuit.
Digital data RFDATA output from the data slice circuit is input to a synchronous signal separating circuit
40
, phase comparator
41
and relative frequency detector
42
. Data DATA is created from the digital data RFDATA. A synchronous signal PFCK is output from the synchronous signal separating circuit
40
. An output voltage CONTV of a filter amplifier
43
is determined by an output signal of the phase comparator
41
and output signal of the relative frequency detector
42
. A VCO (Voltage Controlled Oscillator)
44
is controlled by the output voltage CONTV.
In this example, the frequency of the output clock of the VCO
44
is converted by frequency dividers
45
to
48
and selector
49
to ½
n
times (n=0, 1, 2, 3, 4). That is, through the switching of the selector
49
in accordance with the data rate, the frequency division ratio of the output clock of VCO
44
is selected from five combinations (x1, x2, x4, x8, x16). The selector
49
is controlled by a system controller.
The output clock of the selector
49
which has a frequency corresponding to the data rate becomes a bit clock PLCK. Thus the bit clock PLCK is synchronous with the data rate. Further, the bit clock PLCK is input to the synchronous signal separating circuit
40
, phase comparator
41
and relative frequency detector
42
. Thus the synchronous signal PFCK is also synchronized with the data rate.
The data DATA, bit clock PLCK and synchronous signal PFCK are passed through buffers
52
,
53
and
54
and output from the PLL-synchronous signal separating circuit.
The data reproduction method for the disk driver are two kinds: a CLV (Constant Linear Velocity) and CAV (Constant Angular Velocity). In recent years, however, a mainstream has been changed from a system for rotating a disk at a CLV velocity toward a system for rotating a disk at a CAV velocity. The reason is that it is not necessary to change the rotation velocity of the disk for CAV reproduction.
Explanation will be given below about the CLV reproduction and CAV reproduction.
The CLV reproduction is characterized in that, by the rotation velocity of the disk, the velocity (linear velocity) at which the scanning of a laser beam is made on the track of the disk is made constant and hence the rate of the read data is made constant even on any position (radial direction) on the disk. For the CLV reproduction, the data rate is made at all times constant from an innermost circumference to an outermost circumference of the disk and there is an advantage that the processing of the data is easier and less error is produced.
In the CLV reproduction, however, the rotation velocity of the disk varies as set out above. Stated in more detail, the scanning rate of the laser beam at a normal reproduction time is proportional to the irradiation position (radial direction) of the laser and, in order to make the scanning rate of the laser beam constant, the rotation speed of the disk has to be lowered as the irradiation position of the laser beam is moved from the innermost circumference side to the outermost side of the disk. And the maximum value of the rotation speed of the disk becomes about 2.5 times the minimum value.
On the other hand, on the disk drive apparatus used as a computer peripheral equipment, the seek operation (the operation by which the irradiation position of the laser beam is moved across the track) is effected very frequently. For the above-mentioned CLV reproduction, each time the seek operation is effected, the rotation speed of the disk has to be varied greatly.
If the rotation speed of the disk is varied more number of times, there is a disadvantage that a vast power consumption of the disk motor occurs in the driving of the disk. Further, as the power consumption is increased, more heat is generated in the disk motor, thus exerting a bad influence over the driving of the disk drive.
For the CAV reproduction, on the other hand, the advantage of the CLV reproduction acts as a disadvantage and the disadvantage of the CLV reproduction as an advantage. That is, for the CAV reproduction, the
Kabushiki Kaisha Toshiba
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Tran Thang V.
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