JPH0621081Y2 - Spindle motor servo controller - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention relates to a spindle motor servo controller for a CD player, and more particularly to a servo controller for switching the gain of the spindle servo according to the disk size.

<Prior Art> In an optical disk player, for example, a CD player, a CD mounted on a spindle motor is rotated at a constant linear velocity and data is read by a pickup from the CD. In such a constant linear velocity control, a frame synchronization signal included in the RF signal that is the output signal of the optical pickup is generated, and the frequency and phase of the frame synchronization signal are always the same as the frequency and phase of the signal generated from the reference signal generator. The frequency difference and the phase difference are detected so that they coincide with each other, and the rotation speed of the spindle motor is controlled by feedback.

By the way, initially, the CD system started with a disc size of 12 cm, and a CD with a disc size of 8 cm (generally called a CD single or 8 cm CD) was added to the variation. Along with this, dual-use players for 8 cm CD and 12 cm CD have appeared as CD players. If the material is the same for 8 cm CD and 12 cm CD, the weight of the disc is proportional to the square of the radius, so there is a weight difference of about 2.3 times.

<Problems to be solved by the invention> When playing back an 8 cm CD with a dual-purpose player, the 8 cm CD
Since the disk inertia is smaller and the load applied to the spindle motor is smaller than that of the 12 cm CD, the 12 cm CD
When a drive signal with the same gain as when controlling the rotation speed of is applied to the spindle motor, the rotation speed of 8 cm CD, which is light in weight, tends to overshoot the control target speed.
In particular, there is a problem in the in-vehicle CD player that the CLV servo is disengaged due to rolling due to disturbance or the like.

Therefore, the applicant of the present application discloses an optical disk player, which detects the size of a disk, reduces the gain of the spindle motor servo system when the disk size is small, and increases the gain when the disk size is large, as Japanese Patent Application No. 1-2822. Proposed on January 13, 2001.

However, in the proposed optical disc player, the spindle motor (disc motor) may be activated in the state where the servo gain is reduced. In such a case, the gain is reduced, so that a sufficient activation torque is generated. However, there is a problem in that the CLV servo cannot be applied (for example, it does not rotate).

In view of the above, an object of the present invention is to provide a spindle motor servo control device which switches a gain based on a disk size and can generate a sufficiently large torque (starting torque) at the time of startup even if the disk size is small. It is to be.

<Means for Solving the Problem> In the present invention, the above-mentioned problem is achieved by a synchronization signal detection circuit, a constant linear velocity control circuit, a sensor for detecting the size of a disk,
This is achieved by a gain switching circuit that switches the gain of the spindle motor servo system, and a gain switching signal generator.

<Operation> When the sync signal is not detected from the signal read from the disk (during start-up), even if the disk is small, the gain of the spindle motor servo system is not lowered and the sync signal is detected when the linear velocity approaches constant. Gain (when the servo is locked), lower the gain for the first time. As a result, a sufficient torque can be generated at the time of start-up, the CLV servo can be enabled, and an overshoot or a situation where the servo is lost can be eliminated.

<Embodiment> FIG. 1 is a block diagram of a CD player including a spindle motor servo controller according to the present invention. In the figure, 1 is a CD (compact disc), 2 is an optical C
An optical pickup 3 for reading the digital information recorded on D1 is an RF amplifier for amplifying the pickup output and shaping and outputting the waveform, and a reference numeral 4 is for extracting a frame synchronization signal SYS from the EFM signal output from the RF amplifier. The sync signal detection circuit outputs a sync detection signal SDT that is high level when the frame sync signal is detected. The frame synchronization signal SYS can be reproduced only when the rotational linear velocity of the disk is within several percent of the specified linear velocity (in the servo lock state), and cannot be reproduced otherwise. Then, during reproduction of the frame synchronization signal SYS, constant linear velocity control (CLV constant control) is performed using the frame synchronization signal.

Reference numeral 5 is a pseudo sync signal generator. The frame synchronization signal SYS cannot be detected from the EFM signal unless in the servo lock state. Therefore, when the servo lock state is not established, a pseudo sync signal SYS 'is generated from the pseudo sync signal generator 5 and servo control is performed using the pseudo sync signal to keep the disk rotation speed within a range of several% of the constant linear speed. Bring This pseudo-synchronous signal generation unit 5 detects the shortest 3T or the longest 11T (T is 1 / 4.3218 MHz) pulse from the EFM signal and the shortest / longest pulse detection unit 5a and the shortest or longest pulse length. (588/3) times or (588/11)
It has a pseudo sync signal generator 5b that multiplies it to generate a pseudo sync signal SYS '. One frame is composed of 588T.

6 is in the servo unlock state (synchronization detection signal SD
The switch 7 outputs a pseudo sync signal SYS '(T is a low level) and a frame sync signal SYS in the servo lock state (the sync detection signal SDT is a high level). Reference numeral 7 is a linear velocity constant circuit (CLV circuit). / V converter 7a that outputs a voltage signal V proportional to the difference between the output signal frequency and the linear velocity frequency, a crystal oscillator 7b that generates a system lock signal CL, the phase difference between the output signal of the switch 6 and the system lock. It has a phase comparator 7c which outputs a voltage signal Vp according to

8 is an adder circuit for adding the frequency voltage signal V and the phase voltage signal Vp, 9 is a spindle motor drive circuit, 10 is a spindle motor, 11 is a system controller for controlling the entire system, 12 is a disk size sensor for detecting the size of the disk. , 13 are gain selectors for switching the gain of the spindle motor servo system by turning on / off the switch SW, and make the gain smaller when the switch is on than when the servo system gain is off.

Reference numeral 14 is an AND gate for generating a gain switching signal GCT, which (1) generates a switch-on signal (signal GCT is at a high level) only when the disc is small and the synchronization signal SYS is detected, and (2) At other times, the switch-off signal (the signal GCT is at the low level) is generated.

That is, the switch SW is turned on to reduce the servo gain only when the disk size is small and the sync signal is detected, and when the sync signal SYS is not detected even when the disk size is small and When the disk size is large, the switch SW is turned off and the servo gain is large.

Hereinafter, the gain switching control of the present invention will be described when the spindle motor is started and when the servo is locked.

(a) When the disk size is small When the spindle motor is started, the frame synchronization signal SY is kept until the disk rotation speed falls within the range of several% of the constant linear speed.
S is not detected. Therefore, the sync detection signal SDT is at a low level, the pseudo sync signal SYS 'is input to the CLV circuit 7 instead of the frame sync signal, and constant linear velocity control is performed using this pseudo sync signal.

At this time, since the disk size is small, the system controller 11 outputs a high level size signal SZ to the AND gate 14. However, the AND gate 14 cannot output the high level gain switching signal GCT because the synchronization detection signal SDT is at the low level, and in the end, the gain switching device 1
The switch SW of 3 is turned off, and the gain is high. Therefore, when the spindle motor is started, the spindle motor can easily start rotating due to the high gain.

After that, the spindle motor continues to rotate, and if the disk rotation speed falls within the range of several% of the constant linear velocity, the synchronization signal detector 4 detects and outputs the frame synchronization signal SYS, and also detects the high level synchronization. The signal SDT is output.

As a result, after that, the frame synchronization signal SYS is changed to the CLV circuit 7
Is input to the constant linear velocity control. Then, at this time, the gain switching signal GCT which is the output of the AND gate 14
Becomes high level, the switch SW is turned on, and the servo gain is lowered. That is, when the size of the disk is small, the gain is switched to the small value only when the servo lock state is set, whereby it is possible to prevent the situation where the overshoot or the servo goes off thereafter.

(b) When the disk size is large When the disk size is large, the system controller 11 outputs the low-level size signal SZ, so that the AND gate output is low regardless of whether the frame synchronization signal SYS is detected. As a result, the switch SW of the gain switch 13 is turned off, the gain is always maintained at a high level, and smooth constant linear velocity control becomes possible.

<Advantages of the Invention> According to the present invention, when the sync signal is not detected from the signal read from the disk (at start-up), even if the disk is small, the gain of the spindle motor servo system is not lowered and the linear velocity is not decreased. When the sync signal is detected to approach a certain level (when the servo is locked), the gain is reduced for the first time, so that sufficient torque can be generated at the time of startup to enable the CLV servo. Also, when the servo is locked, overshoot or overshoot occurs. It is possible to eliminate the situation where the servo goes off.

[Brief description of drawings]

The figure shows C including the spindle motor servo controller of the present invention.
It is a principal part block diagram of a D player. 1 ... CD, 4 ... Sync signal detector 5 ... Pseudo sync signal generator 7 ... CLV circuit 11 ... System controller 12 ... Disk size sensor 13 ... Gain switcher, 14 ... AND gate

Claims (1)

[Scope of utility model registration request] 1. A sync signal detecting circuit for detecting a sync signal included in a signal read from a disk, a pseudo sync signal generator for generating a pseudo sync signal when the sync signal cannot be detected, a sync signal or a pseudo sync signal and a system. Constant linear velocity control circuit that controls the rotation of the spindle motor at a constant linear velocity using a clock signal, sensor that detects the size of the disk, gain switching circuit that lowers the gain of the spindle motor servo system when the disk is small, and a synchronization signal is detected A spindle motor servo control device comprising: a gain switching signal generating section that generates a control signal for reducing the gain when a sync signal is detected, and does not reduce the gain even when the disk is small, when the disc is small.