JPH03156735A - Optical disk search device - Google Patents

Abstract

PURPOSE:To make the search time for a CLV disk the same as that for a CAV disk by applying reproduction with the input control of a buffer memory and the track kick control while keeping number of revolutions of a spindle motor to a value close to number of revolutions in the innermost circumference of the CLV disk. CONSTITUTION:A ratio of an output of an optical pickup radial direction position sensor 28 to the radius of inner most circumference is obtained, the frequency of an output of a reference clock generator 27 is multiplied by a value of a number of revolution multiple calculation device 29, and an input address for a buffer memory 402 receiving a band-split of an output of the optical pickup 2 is revised by an output of a multiplier 406, and an output address of the buffer memory 402 is revised by an output of the reference clock generator 27. The input period of the buffer memory 402 and the tracking are controlled by the output of the calculator 29 to be the input. Thus, even when the optical pickup 2 is at any position, the number of revolutions of a spindle 18 is kept to a speed close to the speed at the innermost circumference. Thus, the search time is decrease as near as that of a CAV disk.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a search device for optical discs with constant linear velocity.

Conventional technology In recent years, high-speed search of optical discs has become important.

The recording method uses a constant linear velocity method (
Hereinafter, it will be abbreviated as CLv. ) and the constant angular velocity method (hereinafter abbreviated as CAV), which is characterized by high-speed search. Both types are used for video discs. Below, C
A video disc using the LV system will be explained.

As a conventional optical disc search device, for example, "Laser Disc Technical Book" ASCII Publishing Co. L5BN
4-87148-20G-5.

FIG. 7 is a block diagram showing the configuration of a conventional optical disc search device.

In FIG. 7, 1 is an optical disk, 2 is an optical pickup, 3 is a preamplifier, 4, 6 and 8 are band pass filters (hereinafter abbreviated as BPF), 5, 7 and 9 are FM demodulators, 10 11 is an EFM demodulator, 12 is a horizontal synchronization signal separator, 13 is a phase comparator, 14 is a reference horizontal synchronization signal generator, 15 is a reference clock generator, 16 is a compensation amplifier, 17
is a drive amplifier, and 18 is a spindle motor.

Next, this operation will be explained.

An optical pickup 2 tracks a pit row on an optical disk 1 and outputs a high frequency signal. This output is input to the preamplifier 3. The output of this amplifier 3 is passed through a BPF 4 and then regenerated into a video signal by an FM demodulator 5. Similarly,
The output of the amplifier 3 is passed through the BPF 8 and then converted into the first audio signal at the FM demodulator 7.
is reproduced as a second audio signal. Further, the output of the amplifier 3 is passed through LPFlo and then regenerated into a third audio signal and a fourth audio signal by an EFM demodulator 11. The video signal output from the FM demodulator 5 is input to a horizontal synchronizing signal separator 12, where the horizontal synchronizing signal is separated.

On the other hand, the reference clock from the reference clock generator 15 is frequency-divided by the reference horizontal synchronization signal generator 14, and a reference horizontal synchronization signal is output. These horizontal synchronization signals and reference horizontal synchronization signals are input to the phase comparator 13. The output of the phase comparator 13, which is an error signal, is input to a compensation amplifier 16 having low-pass filter characteristics. The output of this amplifier 16 is input to a drive amplifier 17 to drive a spindle motor 18.

Now, assume that the optical pickup 2 is searched from the innermost circumference to the outermost circumference. In the case of a CAV disc, the process completes in about 3 seconds. This is determined by the slider movement time, the tracking kick and retraction time, and the time until the spindle servo is activated.

Problems to be Solved by the Invention However, with the above conventional configuration, in the case of a CLV disk, it takes a long time until the spindle servo is activated, and it takes more than 10 seconds to search from the innermost circumference to the outermost circumference. C.L.
In a V-disc, the rotational speed must be lowered from 180 Orpm at the innermost circumference to about 60 Orpm at the outermost circumference. However, since the mass of the disk is large, it is impossible for a spindle motor to which a limited power supply capacity is supplied to rapidly reduce the rotational speed. Therefore, there was a problem that the search time was long.

The present invention solves the above-mentioned conventional problems, and aims to provide an optical disc search device that has almost the same search time for CLV discs as for CAV discs.

Means for Solving the Problems To achieve this object, the optical disc search device of the present invention uses an optical pickup radial position sensor and a ratio between the output of the sensor and the innermost radius when playing a CL disc. A rotation speed multiplier to be determined, a frequency multiplier that multiplies the frequency of the output of the reference clock generator by the output value of the calculator, and an input of a buffer memory that receives the signal after band-dividing the optical pickup output. a first address counter that updates the address for use with the output of the multiplier;
a second address counter that updates an output address of the buffer memory with the output of the reference clock generator;
The apparatus includes a memory kick controller which receives the output of the calculator and controls the input period of the buffer memory and track kick.

According to the above-described configuration, the present invention performs playback of a CLv disk by controlling the input of the buffer memory and controlling the track kick while maintaining the rotational speed of the spindle motor at a value close to the rotational speed at the innermost circumference.

EXAMPLES Hereinafter, examples of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of an optical disc search device in an embodiment of the present invention.

In FIG. 1, 1 is an optical disk, 2 is an optical pickup, 3 is a preamplifier, 5, 7, and 9 are FM demodulators, 11 is an EFMtI modulator, 12 is a horizontal synchronizing signal separator, and 13 is a phase comparator. , 14 is a reference horizontal synchronizing signal generator, 16 is a compensation amplifier, 17 is a drive amplifier, 18 is a spindle motor,
19. 20 and 21 are variable band pass filters (hereinafter referred to as
It is abbreviated as variable BPF. ), 22 is a low-pass filter (
Hereinafter, it will be abbreviated as variable LPF. , ), 23, 24, 25
and 26 a memory device, 27 a reference clock generator, 2
8 is an optical pickup radial position sensor, 29 is a rotation speed magnification calculator, 30 is a CAV detector, 31 is a memory kick controller, and 32 is a track kick drive amplifier. Here, the constituent elements 1 to 18 are the same as those described in the conventional example.

The optical pickup radial position sensor (hereinafter abbreviated as sensor) 28 is a sensor that detects the radial position of the optical pickup, and is, for example, a potentiometer. This sensor 28 can detect the radial position. This sensor 2
8 is input to a rotation speed multiplier calculator (hereinafter abbreviated as a calculator) 29.

In the CAV detector 30, the 18th, 17th, 18th and 279°280.28th signals within the vertical retrace period of the video signal
When a CLV disc is detected from the signals on each of the first horizontal scanning lines, the calculator 29 calculates the ratio of the rotational angular velocity during normal CLV disc playback to the rotational angular velocity at the innermost circumference using the principle shown below. .

Now, the radius at the innermost circumference is R (cm), the rotational angular velocity is W (1/s), and the radius at an arbitrary position is r
(cm), and the rotational angular velocity is W (1/s), since the linear velocity is constant, ReW=r@w=constant linear velocity,', w/W=R/r Therefore, r=11R( However, if k≧1), then 1
,',=r/R=W/w Note that when the CAV detector 30 detects a CAv disk, k=1. The magnification that is the output of the calculator 29 includes variable BPFs 19, 20, and 21, and variable L
P F 22 is further supplied to memory devices 23, 24, 25 and 26.

Here, an example of the variable LPF 22 is shown in FIG. This is the rotation speed multiplier calculator 2 in the first-order LPF.
Input the value of the magnification from 9 to the selection switch 301,
The connection branch point between the resistor arrays R(1) to R(n) and the input are selectively connected.

On the other hand, FIG. 3 shows an embodiment of a variable bypass filter (hereinafter abbreviated as HPF). This is done in the primary HPF by inputting the value of the magnification from the rotation speed magnification calculator 29 into the selection switch 401 and selecting the resistance series r(1) to r(m).
Selectively connect the connection branch point between up to and the ground potential.

Variable BPF19, 20 and 21 are variable LPF and variable HP
It can be constructed by cascade-connecting F. The output of the preamplifier 3 passes through a variable BPF 19, is demodulated by an FM demodulator 5, and is input to a memory device 23. Similarly, the output of the amplifier 3 passes through the variable BPF 20, is demodulated by the FM demodulator 7, is input to the memory device 24, and is also input to the variable BPF 20.
21, it is demodulated by an FM demodulator 9, and the memory device 2
5 is input. Furthermore, the output of amplifier 3 is variable LPF2
2 and then input to the memory device 26.

Here, the memory devices 23, 24, 25 and 26 will be explained using FIG.

In FIG. 4, 401 is an AD converter, 402 is a buffer memory, 403 is a DA converter, 404 and 405 are address counters, and 406 is a frequency multiplier.

The AD converter 401 converts the analog signal from the previous stage into a digital signal using the sampling clock that is the output of the frequency multiplier 406. A reference clock, which is the output of the reference clock generator 27, is supplied to the frequency multiplier 406, and a clock having twice the frequency of the reference clock is supplied to the AD converter 401 as a sampling clock.
It is supplied to address counter 404 as a counter clock. The reference clock frequency can be determined by the band of the input signal. Therefore, the reference clock generator 27 supplies a clock suitable for each memory device. In the buffer memory 402, this signal is sent to the address counter 404.
Writing is performed using the write signal and address signal that are output from the . Then, it is read out using the successive signal and address signal that are output from the address counter 405 to which the reference clock is supplied. The DA converter 403 converts it into an analog signal using the reference clock.

In this way, for the optical pickup 2 located at an arbitrary radial position, the writing speed to the buffer memory 402 is increased based on the radial position, while the reading speed is kept constant. Then,
The feedback loop allows the rotational speed of the spindle to be maintained at a value close to the speed at the innermost circumference no matter where the optical pickup 2 is located.

By the way, since the writing speed to the buffer memory 402 is higher than the reading speed, if the playback time is long, data will overflow and the buffer memory 402 will not function. Therefore, a method is needed to properly perform the kick and input the signals separately. This is controlled by a memory kick controller 31. A memory control signal is then output and supplied to the address counter 404.

This control method will be explained using FIG. 5. FIG. 5 shows the time relationship between the input and output of the buffer memory 202 under the control of the memory kick controller 31.

This example deals with the case where =3. This almost corresponds to the outermost circumference, and there are 6 fields in one circumference. The horizontal axis shows the rotational time axis, and the vertical axis shows the radial time axis.

Enter the memory input field number■■■■■■■■■...
・, set the memory output field number (1) (2) (3)
(4) (5) (6) (7) (8)... In the first half of the first stage, (1) is output while rotating half a revolution while inputting ■■■. In the second half of the cycle and the first half of the second stage, no input is made, and (2) and (3) are output, respectively. During this time, perform a backward kick for one track. The period during which a backward kick is possible is shown by a thick solid line in the figure. In the second half of the second stage ■
Outputs (4) while rotating half a revolution while inputting ■■. In the first and second half of the third stage, (5) and (lli) are outputted without inputting. During this time, perform a backward kick for one track. Similarly, for the fourth and subsequent stages, (7) is output while rotating half a revolution while inputting ■■■. In the second half, no input is made and (8) is output.

Next, a summary of this processing process is shown in FIG. a
is an integer, and represents the start phase of the memory output when the phase of the -period is 2. b is a positive number, and represents the start phase of memory input when the phase of -period is 2. i is the number of fields that are consecutively input into the memory. In the first stage of FIG. 5, the start phases of memory input and output are both at the left end. At this time, both a and b are set to O.

Then, i is increased sequentially from 1, (a+1)k-(b
+i) Repeat until ≧2. Here, the output data of the AD converter 401 for each field, ie, the time T/, is input into the memory until the time difference between the ends of the same field between the memory output and the memory input becomes larger than the time required for one revolution. However, T is 1 field period 18.7
Let it be ms. Thereafter, a signal for kicking one track backward is sent to the track kick drive amplifier 32. Return the next start phase of the memory input by the kick amount, and also reset the number of fields by setting a+i-2 to a, and b
Set +i to b. Furthermore, in order to prevent the values of a and b from becoming too large, if a≧2 and b≧2, a−2 is changed to a
Then, set b-2k to b and reduce both by one rotation. After the memory input is completed, it is checked whether one rotation, that is, 2T has elapsed.

When the elapsed time has elapsed, a memory control signal for activating the address counter 404 is sent to the address counter 404, and the output data of the AD converter 401 for the time T/ is input to the memory 402. Memory kick controller 3 with such functions
1 is a CPU and a RAM.

This can be easily realized with a microcomputer configured with ROM or the like.

The output of the memory device 23 is a video signal. This is also fed to the horizontal sync signal separator 12. The outputs of memory devices 24 and 25 are a first audio signal and a second audio signal.

The output of the memory device 26 is supplied to the EFM demodulator 11;
A third audio signal and a fourth audio signal are obtained.

By the above method, in the case of a CL disk, the rotational speed of the spindle can be maintained at a value close to the speed at the innermost circumference no matter where the optical pickup 2 is located, and in this state, video, audio, etc. Can be played. Even if there is an error in the magnification k or if the frequency multiplier can only take discrete values for k, the spindle rotation speed is 1800 rpm.
It is in the vicinity of When the optical pickup moves, the spindle rotation speed is slightly changed according to the value of k.

However, the rotational driving force required for this change is small, and therefore the rotation settling time is also minute. Therefore, the time required until spindle servo is applied can be made equal to that of a CAV disk, and as a result, the search time can also be made as short as that of a CAV disk.

Effects of the Invention As described above, the present invention has the following advantages in the reproduction of CLV discs.
An optical pickup radial position sensor, a rotation speed multiplier that calculates the ratio between the output of the sensor and the innermost radius, and a frequency multiplier that multiplies the frequency of the output of the reference clock generator by the value of the output of the calculator. a first address counter that uses the multiplier output to update the input address of the buffer memory, which inputs the signal after band-dividing the optical pickup output; and a first address counter that updates the input address of the buffer memory using the multiplier output; The optical pickup includes a second address counter that updates an output address, and a memory kick controller that receives the output of the calculator as an input and controls the input period of the buffer memory and the track kick. Regardless of the position of the spindle, the rotational speed of the spindle can be maintained at a value close to the speed at the innermost circumference.
In addition, video, audio, etc. can be played back in this state. Therefore,
The time it takes for the spindle servo to start can be made equal to that of a CAV disk, and as a result, the search time is also comparable to that of a CAV disk.
It can be made as short as a V-disc.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of an optical disc search device in an embodiment of the present invention, FIG. 2 is a block diagram showing the configuration of a variable LPF, FIG. 3 is a block diagram showing the configuration of a variable HPF, and FIG. 4 is a block diagram showing the configuration of a variable HPF. A block diagram showing the configuration of a memory device,
Figure 5 is a time relationship diagram between the input and output of the buffer memory.
FIG. 6 is a process diagram of the memory kick controller, and FIG. 7 is a block diagram showing the configuration of a conventional optical disc search device. 19-21...Variable BPF, 22...Variable L
PF123-26...Memory device, 27...
・Reference clock generator, 28... Optical pickup radial position sensor, 29... Rotation speed magnification calculator, 30... CAV detector, 31... Memory kick controller, 32... Track kick drive amplifier,
401... AD conversion tjk5, 402... Buffer memory, 403... DA converter, 404
．． 405... Address counter, 406... Frequency multiplier.

Claims (2)

[Claims] (1) Constant linear velocity method When reproducing optical discs, an optical pickup radial position sensor, a rotation speed magnification calculator that calculates the ratio between the output of the sensor and the innermost radius, and the value of the output of the calculator are used as a standard. a frequency multiplier that multiplies the frequency of the output of the clock generator; and a first address counter that updates, with the output of the multiplier, an input address of a buffer memory that receives a signal after band-dividing the optical pickup output. , a second address counter that updates the output address of the buffer memory with the output of the reference clock generator; and a memory that receives the output of the calculator as an input and controls the input period of the buffer memory and track kick. An optical disc search device comprising a kick controller. (2) The optical disc search device according to claim 1, wherein an FM demodulated signal is used as the band-divided signal.