JPS5848242A - Information reproducer - Google Patents

Abstract

PURPOSE:To start a disk at an optional radius position, by accelerating again a CLV disk until it reaches a state in which a spindle servo control can be locked after detecting the end of the pull-in action of a focus servo control. CONSTITUTION:A pull-in action is secured for a focus servomotor when a focus servo control signal (s) is set at a high level. Thus the pull-in detection signal (u) is set at a high level. As a result, the switch signal (m) is set at a high level to turn on the tracking servo control. At the same time, an accelerating action is carried out with the switch signal (z) kept at a high level. When the reproduced extracting signal (x) is set at a high level, the signal (z) is set at a low level. At the same time, the switch signal (y) is set at a high level, and a spindle servo action is performed to end the start of a disk.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an information reproducing device, and more particularly to a recorded information reproducing device for a recording disk recorded using a constant linear velocity method.

In recent years, optical discs have become available as recording media that can record information at high density, but in order to achieve higher density, tracks are recorded at all radial positions, rather than at a constant rotational angular velocity like conventional music records. A constant linear velocity type disk with a constant linear velocity in the direction (Con5tant)
Linear VelocityDise, hereinafter C
A method called LV disk (abbreviated as LV disk) is being used.

In addition, by recording digital signals such as PCM signals on such high-density recording media, it is possible to use it as a compact music record that has good sound quality and can be recorded for a long time, or as a high-density memory. There is a lot of research going on. During playback of such discs, in order to obtain a predetermined linear velocity, it is common to extract the playback clock from the playback signal, and apply spindle serge so that the extracted clock frequency and phase match the reference clock. Therefore, the recording signal is modulated using a self-clocking modulation method.

As described above, it is possible to perform a CLV circuit using a circuit that matches the frequency and phase of the extracted clock with the reference clock, but for this purpose it is necessary to be able to extract the reproduced clock from the reproduced signal. Recovered clock extraction is generally performed using a filter tuned to a predetermined clock frequency or a PLL (phase-locked router'), but since these utilize the frequency selection characteristics of the filter, it is difficult to extract the recovered clock if the input frequency is not near the predetermined frequency. Unable to extract clock.

In the case of CLV, the product of the playback recording track radius and the disk rotation speed is constant, so the playback clock can be set by detecting the playback recording track radius using, for example, a potentiometer and detecting the disk rotation speed using, for example, a frequency generator in the playback device. The applicant of the present application has filed an application for a method that makes it possible to extract a reproduced clock by rotating the disk so that the linear velocity is approximately at a predetermined speed so that the input frequency is close to a predetermined frequency even when extraction is not possible. −
124285. However, potentiometers and frequency generators are generally expensive, making it an obstacle to supplying inexpensive consumer players.

It may be harmful.

So, - it takes sir? It is desirable to be able to extract a reproduced clock without providing a loop, and a new method for this purpose has been filed in Japanese Patent Application No. 80248/1983, which was also filed by the applicant of the present invention. This is related to the start of disk rotation, for example, by monotonically increasing the rotation speed from a rotation speed that is sufficiently lower than the rotation speed at which a predetermined linear velocity is achieved, the clock is extracted by passing around the rotation speed at which the reproduced clock can be extracted. When this happens, it turns on the spindle serger. In that case, it is first necessary to obtain a rotational speed sufficiently lower than the predetermined rotational speed and then increase the rotational speed.

On the other hand, in the case of a reflective optical disc reproducing apparatus, it is well known that in order to obtain a reproduced signal, it is necessary to perform a focus search first. Various methods for detecting the error signal of focus serve have been announced, but in order to obtain an accurate error signal, the distance between the disk and the objective lens must be within a predetermined distance glass minus several tens of micrometers. It must be in This is generally called the Focus Serve carburetion range. On the other hand, the surface runout of the disc is usually much larger than that of a carburetor range, so when performing focus retraction, the lens is first kept far away from the disc to prevent the lens from coming into contact with the disc. The method used is to slowly bring the lens closer to the disk, detect when the lens passes within the capture range (in-focus detection), and then turn on the focus puller.

For example, in Figure 1, when the lens is brought closer to the disk, the error signal voltage changes from α → b → C on the curve g, and when this exceeds a predetermined voltage d, it is determined that it is within the capture range. to turn on Focus Sarderog.

If the disk remains stationary (not rotating) when performing focus pull-in in this way, the following problems may occur. If there are many pits in the vicinity of the light spot where the light spot hits D and S, the amount of reflected light will be small, and the resulting error signal curve will have a small amplitude as shown in Figure 1. The amplitude becomes large as shown in e in Figure 1. In such a case, it is difficult to detect in-focus at a fixed position on the horizontal axis in Figure 1,
In the worst case, focus may not be able to be pulled in. Also, even if in-focus detection is possible, curve e
−? The fact that the slope near the origin varies as shown in / means that the first round of Focus Surger Rouge is uneven, and Fu, Orcus Sur? The operation will be different from the operation set as a loop, and in severe cases, it is possible that oscillation may occur. If the disk is rotating when focus pull-in is performed, the number of bits as described above is averaged by setting the antenna that obtains the position error signal to a low-gust characteristic, and the position error signal is The curve becomes as shown in g in the figure, and the focus pull-in becomes stable due to the designed operation.

Therefore, the disk must be rotating when focus pull-in is performed, but considering that the recovered clock is then extracted as described above, the disk rotation speed when focus pull-in is equal to the normal speed at the radial position at that time. It is necessary to keep the rotation speed sufficiently lower than the rotation speed and accelerate after the focus is pulled in. Of course, as described in the patent specification of Japanese Patent Application No. 56-80248, the focus may be pulled in at a rotation speed higher than the normal rotation speed, and then the rotation speed may be monotonically decreased. Monotonous increase and monotonous decrease may be repeated until clock extraction becomes possible. Also in this case, tracking server? It is possible to extract the clock even if the focus is not applied, but in order to be more reliable, it is possible to extract the clock after the focus is detected. It is also possible to turn on the engine and accelerate the speed.

Next, the time required for focus pull-in will be described.

Focus sir as mentioned above? The capture range is very narrow, about a few micrometers. Therefore, if the speed at which the lens approaches the disk during focus retraction is fast, the time it takes to pass through the capture range will become extremely short. Since the bandwidth of the 〒directional focus is limited,
If the time taken to pass through the capture range is too short, the lens will go too far and will not be retracted. Therefore, the movement speed of the lens when retracting is limited,
So focus sir? The time required for retraction may be about 0.5 seconds to 1 second, although it depends on the band of the lens and the distance traveled by the lens. Also, considering protection in case focus cannot be pulled for some reason, it is possible to repeat the focus pull operation two or three times, in which case it may take a considerable amount of time to complete focus pull. It is also possible.

During this time, it is not desirable if the rotational speed of the disk becomes too low or higher than the normal rotational speed. That is, if it is too low, the disk comes close to stopping as described above, and if it is too high, the clock cannot be extracted even if it is subsequently accelerated. Therefore, it is desirable to maintain the disk rotational speed at approximately a predetermined value from the time the focus pull-in operation is started until it is completed.

The above was about what happens at startup, but
In addition to waiting for startup, there are times when it is necessary to maintain the rotational speed. For example, when it becomes clear that clock extraction is no longer possible after fast-forwarding the relative position in the direction perpendicular to the recording track pick-up, the rotation sensor? When the playback light spot protrudes onto the mirror surface while interrupting the playback or during fast-forward operation, the rotation sensor? This is a case where the rotation serve is interrupted during all interruptions or during fast forward operation.

As mentioned above, it is necessary for a disk rotation means in a disk playback device to be able to perform at least each of the following operations: stop operation, acceleration operation, rotational speed holding operation, and spindle serve operation, and also when these operations are performed during focus pull-in and In addition to this, it is necessary to switch to a predetermined operation when performing rotational speed holding operation.

Therefore, it is an object of the present invention to provide an information reproducing apparatus that can perform the above-mentioned necessary operations and that can be activated from any radial position on a CLV disk.

The information reproducing device according to the present invention responds to a startup command by rotating C toward a predetermined rotation speed that is sufficiently smaller than a necessary linear velocity for a predetermined period of time.
The LV disk is accelerated, and after reaching this predetermined rotation speed, the focus serve pull-in operation is performed while maintaining this rotation speed, and when the end of the focus serve pull-in operation is detected, the spindle sir? C until the server can be locked.
It is characterized by being configured to re-accelerate the LV disk.

The present invention will be explained below using the drawings.

Figure 2 is a block diagram of an embodiment of the present invention, where ① is a reflective optical disk on which signals are recorded at a constant linear velocity using a self-clocking modulation method, and 2 is a DC motor for rotating the disk. be.

3 is an optical pickup for reproducing signals, which includes focus signal detection, tracking signal detection, RF
It includes means for signal detection, focus lens drive, and tracking mirror drive.

Further, this pickup can be moved in the radial direction of the disk by a tracking mirror drive means or another feeding means (not shown).

4 is a differential amplifier that generates a tracking error signal k from the tracking signals j and j', and 5 is a drive circuit that generates a tracking mirror drive signal l from the tracking error signal k.
It is assumed that the luzo can be turned on and off by the switch SW1, and is turned on when the switch signal m is at a high level. 6 is a differential amplifier that generates a focus error signal p from the focus signals n and n'; 7 is a drive circuit that generates a focus lens drive signal q from the focus error signal p and the focus pull-in control signal t. Focus sir is a circuit sir? The loop can be turned on and off by the switch SW2, and is turned on when the switch signal r is at a high level. 8 is a focus servo pull-in control circuit, and 9 is a detection circuit that detects that focus servo pull-in has been performed. When the focuser control signal S becomes high level, the focuser starts a pull-in operation, and when the focuser is pulled in, the focuser pull-in detection signal U becomes high level.

10 is a clock extraction signal that extracts the clock frequency from the RF signal τ reproduced by the picker f3, compares the frequency and phase with the reference clock frequency, generates the spindle error signal W, and indicates whether or not the reproduced clock has been extracted. Outputs X. . The spindle sirer is the signal generating circuit.

Assume that the clock can be extracted when X is at a high level. It is assumed that this spindle serve loop can be turned on and off by a switch SW, and is turned on when switch signal 1 is at a high level.

SW4 is a switch that operates during acceleration operation and rotation speed holding operation, and SW4 is turned on when switch signal 2 is at a high level. 11 is O (amplifier.-B
is a negative DC voltage. Reference numeral 12 denotes a control signal generation circuit that controls the operation of each section.

First, a method for detecting that focus pull-in has been performed will be described. The focus signals n and n' will not be described in detail, but assuming that a focuser using a known astigmatism is used, n and n' are the focus near the in-focus point, and the signal from the disk to the light receiving element. Both levels rise as the amount of reflected light increases. Further, by taking the difference, a focus error signal p as shown in FIG. 1 is obtained.

Therefore, if the focuser is working normally, the levels of the focus signals n and n' will increase near the in-focus point as described above, so for example, the level of n' will be the predetermined level. If the period of time exceeds a predetermined time width, it can be determined that focus servo pull-in has been performed. The focus servo pull-in detection circuit 9 may be configured in this manner, for example, but it is not limited to this.

Next, the focusser will explain how to pull in the image.

When the focus servo control signal 8 is at a low level, the focus servo pull-in control circuit 8 sets switch No. 8 r to a low level to turn off the focus servo and sets the focus servo pull-in control signal t to a predetermined level, thereby controlling the focus. The drive circuit 7 sets the level of the focus lens drive signal q so that the lens moves away from the disk. When the focus servo control signal 8 becomes high level, the focus servo pull-in control circuit 8 sets the focus servo pull-in control signal t to a predetermined level, and thereby the focus servo drive circuit 7 adjusts the level of the drive signal q so that the lens is attached to the disk at a predetermined level. Try to approach at speed. When it enters the capture range, the output p of the differential amplifier f6 has a waveform as shown in FIG.
(in-focus detection), the focuser sets the pull-in control signal t to a predetermined level that does not have any effect on the drive signal q, and also sets the switch signal r to high to turn on the focuser. Normally, this causes the focuser to be pulled in, which is detected by the detection circuit 9, and the focuser pull-in detection signal U becomes high level.In response, the player control circuit 12 causes the focuser to raise the control signal 8 to a high level. Maintain the same level and continue to focus. Also, if the focuser fails to pull in for some reason, the focuser control signal 8
・Since the focuser pulls in and the detection signal U does not become high rail within a predetermined time after it becomes an impel, the player controls the path. U-bow HkR 7 fails and c3 is detected.

The focuser can once set the control signal 8 to a low level to move the lens away from the disk, and then set the control signal 8 to a high level again to repeat the same operation. Although the focuser is retracted in the above manner, it is not limited to this method.

The tracking serve part is generally necessary in a normal reflective optical diffuser, and its operation is not the gist of the present invention and will not be described in detail. 10 m s e
Is there a tracking sir within c? It is assumed that the withdrawal is made. This value is a value that can be fully realized.

Next, the disk rotating portion will be explained using a specific numerical example. As a recording disk, diameter: 120”
Hole diameter: 15gm s Weight: 30gw s Predetermined linear velocity: 1. '3m1sec, innermost track radius: 23mm, outermost track radius: 58IllIE, the moment of inertia J of this disk is Jta0.56
It is calculated as gcm52. □Linear velocity is 1.3m1s
The rotational angular velocity of the disk to achieve ec is w4-56.5m/a (=54OR, PM) at the innermost circumference, and woz 22.4 rad/s (at the outermost circumference).
z 214 RPM).

As motor 2, diameter: 22"i' @ total length not including output shaft: 40" + DC resistance: 300. Torque constant kt: 200gcrrL/A. When the above-mentioned disk 1 is attached to such a small DC motor, the friction torque is about 5 gcIIL. In addition, the friction torque in this case is the part of the torque generated on the motor shaft that is not consumed to change the rotational angular velocity of the disk l, which is the load, and as mentioned above, the maximum rotation speed is as low as 540 RPM. , there is almost no viscous damping component, and therefore the value is almost constant regardless of the rotation speed.

Now, if the armature current of the motor is i, the torque M1 generated on the motor shaft is M==ktXi ・・・・・・・・・・・・・・・
・(1). Of this, 5 acm is consumed by friction, so the torque M2 consumed to change the rotational angular velocity of disk L is M2:Ml-5 (2 ). Now if f = o, o: 15A, then from equation (1) M
, = 59CIrL, so from equation (2), M2 = 0
becomes.

That is, while the armature current i is 25 mA, the rotational angular velocity of the disk hardly changes to i.

Next, FIG. 4 shows a comprehensive voltage-current conversion circuit.

In this circuit, if the current flowing from the operational amplifier 11 to the load motor 2 is i, when R3<<R,, 2, i almost contains R5, and the current flowing toward R2 can be ignored. Therefore, the following equation holds between Ein and i.

Furthermore, it is clear that if Ein and R4 are disconnected, i=0.

In Figure 2, if -B is -5V, R,4 is 100Ω, R2 is 10&Ωs, and R,s is 2Ω, when both switches SW and SW4 are off, the motor current i is zero. Therefore, the motor is in a stopped state. When only switch SW4 is on, from equation (4), (
is 0.25A, so from equation (1), M.

is 50 gcm. Moreover, when only switch SW4 is turned on at a duty ratio of IO%, i becomes substantially [CO
,025A, and therefore Ml is 5 gcIrl. In this case, the disk becomes a flywheel, and if the on-off repetition frequency is high enough, the motor's rotational speed will hardly change even instantaneously.

Also, when SW4 is off and SW3 is on, a spindle serve loop occurs, and i
is decided, and the usual Sundorsade is done.

Next, the overall operation of the circuit block shown in FIG. 2 will be described. Fourth
In the figure, when switch signal 2 becomes )-invel at time T1, SW4 is turned on, and therefore the motor is M, =
Generates 50gcIrLO shaft torque. Therefore, the disk is accelerated by a torque of M2=4jgm. The moment of inertia J of this disk is 0.56 g as mentioned above.
Since yrcs2, the time T2 after the degree rotation angular velocity has passed
Thereafter, the data ratio is 10cIb and the signal 2 is set to -.Impel. Time T depending on the time width from time T to T2
The number of rotations after 2 can be set arbitrarily. For example, if this time width is 0.2 seconds, the number of rotations after time T2 is 8.
0
RPM) and the predetermined rotational speed at the outermost circumference wo m2
Well below 2.4 rad/s (z214 RPM). Therefore, when the disk is subsequently accelerated, the number of rotations at which a predetermined linear velocity can be obtained is always crossed regardless of the radial position. That is, activation is possible from any radial position.

When the focus therme control signal 8 is set to high level at the same time at time T2, the focus therme & pull-in operation occurs, and at time T, the focus therme? It is detected that the focus has been pulled in, and the focuser's pull-in detection signal U becomes high level. , 5. If for some reason the focus pull-in operation is not completed in one step, the time T2 to T
Even if it takes a few seconds to reach 3, there is no problem as long as the rotational speed is maintained during that time as in the present invention.

At time T3, in response to the fact that the focus sensor's pull-in detection signal became No. 1 impel, the switch signal No. was set to no impel, turning on the trunking sensor ♂, and at the same time, the switch signal 2 was kept at high level again and the second By performing the acceleration operation of
Since, in response to this, the switch signal 2 is set to a low level and the switch signal V is set to a level of no 1 impel, the spindle sirer is operated from time T4 onwards, and the start-up is completed. The bottom part of FIG. 4 shows how the disk rotational speed changes during each of the above operations.

Furthermore, as described above, if it is desired to maintain the disk rotational speed during times other than during startup waiting, this can be done by setting the switch signal 1 to a low level and turning the switch signal 2 on and off at a duty ratio of 10.

In this example, the switch SW4 was turned on with a duty ratio of 100ch during both the period T, ~T2 and the period T3 ~T, but from the purpose of the present invention, during these periods, T
The period from T2 to T3 may also have a large duty ratio, and for example, if the period from T1 to T2 is the duty and the ratio is 1
oos, the period from T3 to T4 may be changed such that the duty ratio is 50%.

It goes without saying that, in addition to switching between holding and accelerating the rotational speed using a linear voltage as in this example, it is also possible to switch, for example, a voltage value of -B.

As described above, according to the present invention, it is possible to start the CLV recording disk from any radial position, and even if the focuser takes time to pull in, a stable starting operation can be performed. Furthermore, since there is no need to detect the track radius or the number of rotations of the disc, the cost is low, making it suitable for consumer digital audio players.

[Brief explanation of the drawing]

Claims (1)

[Claims] A spindle serve means for controlling the rotation of a recording disk recorded by a constant linear velocity method, and a focus server for accurately converging the pickup sudde light onto the recording disk. An information reproducing device that responds to an activation command, comprising means for retracting a focus servo by moving a focus lens to a lockable state, and detecting means for detecting that the focus servo is retracted. means for accelerating the recording disk toward a predetermined rotational speed that is sufficiently lower than the linear velocity required for the rotation, means for maintaining the predetermined rotational speed, and means for commanding the retracting operation of the focus serve during the rotational speed maintenance operation. and means for accelerating the recording disk again to a state in which the spindle motor is able to servo lock in response to the detection of the end of the focus servo pull-in operation by the detection means.