JPS62154234A - Rotation controller for optical disk - Google Patents

Abstract

PURPOSE:To lead quickly a focus-servo into a locking state without damaging an optical disk by containing a means for switching a driving voltage of a motor for rotating the optical disk at the time point when a focus lock signal is supplied from the focus-servo, and raising a revolving speed of the optical disk to a stationary revolving speed. CONSTITUTION:An output voltage characteristic against an input signal frequency (rotating speed) of a speed controlling circuit 17 is selected in advance, and when a rotating speed of an optical disk 1 and a DC motor 2 becomes higher than prescribed 1,800rpm, an output voltage increases from a prescribed value, and it is supplied to an operational amplifier 11 through an inversion amplifier 10 and a resistance R7, therefore, a negative output voltage from the operational amplifier 11 increases in the negative direction, potential difference between both terminals of the DC motor 2 becomes smaller and a rotating speed is decreased. On the other hand, when the rotating speed of the optical disk 1 and the DC motor 2 becomes lower than the prescribed 1,800rpm, on the contrary, the output negative voltage of the operational amplifier 11 becomes higher in the positive direction, therefore, the rotating speed of the DC motor 2 increases, and the rotating speed (revolving speed) of the DC motor 2 and the optical disk 1 is held at the stationary revolving speed 1,800rpm.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to rotation control of an optical disc, and more particularly to a rotation control device at the start of rotation of an optical disc.

Conventional technology In the recording mode of a recordable and reproducible optical disc, for example, the driving current of a semiconductor laser is turned on and off according to pulses according to recorded data, and thereby recording is performed using a radar beam intermittently emitted from the semiconductor laser. Data is recorded. On the other hand, in playback mode,
The green signal described above is reproduced by a laser beam with a constant power, which is increased to an energy υ+W to such an extent that the optical properties of the recording film of the optical disk are not changed by the narrowed light spot.

Therefore, in the playback mode, the laser power is 6 lower than that in the record mode, and the laser power is kept constant to prevent the laser power from becoming excessive and causing erroneous recording or erroneous recorded edge information. value, on the other hand,
In recording mode, make sure that the laser power does not become too low and result in recording with poor S/N due to the effects of noise, and that the laser power does not become too high and the resolution with the VJ pit information deteriorates. It is necessary to control the laser power within an optimal range.

In such an optical disc recording/reproducing apparatus, the focus servo can be pulled in most easily when the optical disc is not rotating. For this reason, if the focus servo is turned on at the same time as the optical disk starts rotating from the point at which the focus servo is retracted, the optical disk will not start rotating immediately due to inertia, and the light beam spot will be placed at approximately the same point. Because it is irradiated for a long period of time, in the case of a sensitive optical disc, the temperature of the irradiated area rises before it starts rotating even in the playback mode with low laser power as described above, causing the recorded edge information to rise. There were problems such as damage to the Also, if the optical disc does not rotate for some reason, it is obvious that the optical disc is
(I will be attacked.

For this reason, conventionally, the focus servo was turned on after the optical disc reached a predetermined steady rotation speed (for example, 1800 rpm).

Problems to be Solved by the Invention However, when the optical disk is rotating steadily, the disturbance frequency to the focus servo circuit becomes high due to the effects of surface runout, etc., and the focus servo is difficult to pull in.

Therefore, the present invention solves the above problems by first starting the rotation of the optical disk at a predetermined low speed, turning on the focus servo in that state, and increasing the rotation speed to a steady rotation speed. The purpose is to provide a control 211 device.

Means for Solving the Problems The optical disk rotation control device according to the present invention includes means for starting the rotation of the optical disk to a first rotation speed lower than the steady rotation speed, and means for starting the rotation of the optical disk to a first rotation speed lower than the steady rotation speed. A means for outputting a focus servo-on signal at a second rotation speed on the way to a second rotation speed, and a means for rotating the optical disk by switching the drive voltage of the motor for rotating the optical disk at the time when the signal is supplied from the focus servo to the 74-Kasuro Tsuki. This consists of a means for increasing the number of rotations to a steady rotation number.

Operation The focus servo is turned on at a second rotational speed on the way to the first rotational speed, which is lower than the steady rotational speed J. That is, the focus servo is turned on when the frequency of disturbances such as surface runout of the optical disk is at a sufficiently low second rotation speed.

Thereafter, the rotational speed of the optical disk is controlled i, lI to a predetermined steady rotational speed by a focus lock signal obtained from the focus 1 nervous system.

Embodiment FIG. 1 does not show a circuit diagram of an embodiment of the apparatus of the present invention. In the figure, an optical disk 1 is rotated by a DC motor 2, and the number of rotations (rotational speed) thereof is detected by a head 3 and a rotation detector 4. In addition, as a rotation speed detection means,
A frequency generator (of a known configuration) that generates a rotation detection signal with a frequency corresponding to the rotation speed of the motor shaft of the DC motor 2.
FG), or it may be a device that optically reads rotation ax+aa signals of a constant rotation 11 recorded in advance on, for example, an annular track outside the program area of an optical disc.

In either case, as shown in FIG. 2, the rotation detector 4 outputs a zero-turn detection pulse having a frequency corresponding to the rotational speed of the optical disk 1 and the DC sweater 2, and a voltage proportional to the rotational speed.

Now, when the disk start (rotation start) switch (not shown) is turned on, a signal of [1- level] is input to terminal 5. It should be noted that the terminal 5 is held at a low level until the controller is stopped. At this time, the focus servo has not been turned on yet, so the focus lock signal is not input to the terminal 6 and is at a high level. Therefore, when the disc start switch is turned on, the output signal of the NOR circuit 7 to which both signals from terminals 5 and 6 are supplied is at a low level, and the output signal from the switch circuit SW+i whose switching is controlled by this signal is on the side closer to the terminal. It is switched and connected to. Furthermore, the polarity of the low level input signal at the terminal 5 is inverted by the inverter 8 and the input signal is sent to the switch circuit SW2.
is applied to the terminal H, and this is switched and connected to the terminal H side. Furthermore, the C1-level input signal of the input terminal F5 is supplied to one input terminal of the two-man power NAND circuit 9. Therefore, the output signal 1) of the NAND circuit 9 is supplied to the other input terminal. The signal from the comparator 13 has a relationship f, c<high level.

The high level output signal of the NAND circuit 9 is applied to the PNP transistor Tr+, turning it off. Since the collector of the transistor Tr+ is connected to the base and emitter of the NPN+ transistor Tr2 via the resistors R3 and Rt, the above-mentioned voltage of the transistor Tr+;
I also turns off the transistor Tr2. The collector of the transistor Trz is connected to the non-inverting input terminal of the inverting amplifier 10, but by turning off the transistor ]'r2, the non-inverting input terminal of the inverting amplifier 10 is grounded only through the resistor R5. .

On the other hand, since the switch circuit SW1 is connected to the terminal side as described above, a predetermined voltage V0 obtained by dividing the power supply voltage by resistors R1 and R2 is applied to the inverting amplifier 10 through the resistor Rs and the switch circuit SW1. One part of the DC motor 2 is supplied to the inverting input terminal and is inverted and amplified here. Applied to the terminal. Since the other terminal of the DC motor 2 is connected to the negative power supply j1 (for example, -15V) via the switch circuit SW2, the DC motor 2 is started by applying the inverted amplified voltage of Vo. As a result, the number of rotations (rotational speed) of the optical disk 1 and the DC motor 2 increase by 1 as soon as the disk star 1 ~ immediately after (the optical disk 1 and the DC motor 2 rotate 1 J at the first rotation speed determined by the DC voltage Vo). The voltage Vo is lower than the steady rotation speed of the DC motor 2 and the optical disk 1 of 1800 rpm.
00 = A value selected to avoid rotation at about 500 rpm.

The rotation speed of the optical disc 1 is 400 to 500 rpa+ as mentioned above.
When the rotation speed reaches a predetermined second rotation speed during the TR, the output rotation detection voltage Ii of the rotation detector 4 voltage value V+
(V+ <V.) J: Rimo becomes a person. ] The comparator 12 compares the levels of the reference voltage v1 and this rotation detection value j1, and outputs a high level signal to the rotation detector [when E becomes larger than the reference voltage vI] via the terminal 14 as an A-cass-on signal. and supplies it to a focus servo circuit (not shown). As a result, when the focus servo circuit is turned on, the pickup 15 is vibrated at a predetermined frequency in a direction perpendicular to the surface of the optical disc 1, and as a result, the reflected light changes (maximum at the focused point position). The output signal changes accordingly. The focus servo circuit detects that this output signal exceeds a predetermined level and that the focus error signal has reached a level near the in-focus point,
This detection output is used to operate a flip-flop, thereby closing the focus servo loop.

The output signal of this flip-flop is sent as a low-level focus lock signal to NOR via terminal 6 in FIG.
It is applied to one input terminal of the circuit 7.

As a result, both of the two input signals of the NOR circuit 7 become low level, so the output signal of the NOR circuit 7 becomes high level, and the switch circuit S W + is switched and connected to the terminal H side. On the other hand, the recorded information on the optical disc 1 is picked up by the pickup 15 (9), and the originally fixed period signal is discriminated and separated by the speed detector 16, and the optical disc 1 is
Speed control circuit 17 as a signal with a frequency corresponding to the number of rotations of
, where it undergoes frequency-to-voltage conversion. As described above, since the switch circuit S W + is switched to the terminal H side when the focus lock signal is received, the output speed error signal of the speed control circuit 17 is connected to the resistor R8 and the switch circuit S
It is supplied to the inverting amplifier 10 through the resistor R7, the amplifier 11, and the switch circuit SW2, respectively, and is supplied to the DC 2, for example, at 1800 ppm. rotation a, II t
fo.

Here, the input signal frequency (rotational speed) vs. output voltage characteristic of the speed control circuit 17 is selected as shown in FIG. When the voltage increases, the output voltage increases from a predetermined value, and this increases the output voltage of the inverting amplifier 10 and the resistor R7.
Since the negative output voltage from the speaker amplifier 11 increases in the negative direction, the potential difference between the two terminals of the direct current becomes smaller and the rotation speed decreases. let

On the other hand, when the rotation degree of the optical disk 1 and the DC motor 1) 2 decreases below the predetermined 1800 rpm, the output negative voltage of the amplifier 11 increases in the positive direction, contrary to the above, so that the rotation speed of the DC motor 2 increases. increases. In this way, the rotational speed (rotational speed) of the DC controller 2 and the optical disk 10 is maintained at a constant rotational speed of 1 and 100 rpm.

The signal used by the speed detector 16 to detect the speed is, for example, a playback horizontal synchronization signal in the playback video signal of the optical disc 1 in the playback mode, and a signal at the position where the information track of the optical disc 1 is formed in the record mode. A guide track (for example,
Patent application Sho 60-141696@, which was proposed earlier by the applicant
There are also playback signals for pre-pits.

When using the playback horizontal synchronization signal, the output of the speed control circuit 17 cannot be distinguished from the playback video signal unless the optical disc 1 reaches a constant rotational speed. The error signal outputs a signal that causes the DC motor 2 to rotate at the maximum speed. As a result of this, the rotation speed of the DC motor 2 quickly reaches the predetermined steady rotation 1+
Go.

rp+al close to upper back.

In addition, in FIG. 1, a comparator 131, a one-rotation detector 4
The level of the rotation detection voltage and the reference voltage V2 (V2<Vl) are compared, and when the rotation detection voltage becomes smaller than V2, a high level signal is output. At this time, if a high level stop signal is input to terminal 5,
The output signal of the NΔAND circuit 9 becomes low level, which turns on the transistors TI'+ and Tr2, and the output type voltage of the inverting amplifier 10 increases in the negative direction, becoming approximately equal to the power supply voltage of (1), and the DC motor Since the potential difference between both terminals of 2 becomes a gap, the DC motor 2 stops rotating.l:1
-ru.

It goes without saying that the present invention can be applied to the rotation control of a CLV type optical disc. In this case, the steady rotation speed is not constant at 1800 rpm, but at 1800 rDI.
It is clear that the distance is gradually lowered in response to the movement of the pickup 15 toward the outer circumference.

Effects of the Invention As described above, according to the present invention, since the focus servo is turned on at a rotation speed slower than the steady rotation speed,
It has features such as being able to quickly pull the focus servo into the one-stop state without having to IF the optical disc.

[Brief explanation of drawings]

Fig. 1 does not show an embodiment of the device of the present invention;
3 and 3 are diagrams showing the characteristics of each main part of the circuit system shown in FIG. 1, respectively. DESCRIPTION OF SYMBOLS 1... Optical disk, 2... DC motor, 4... Rotation detector, 5... Start signal input terminal, 6... Focus lock signal input terminal, 10... Inverting amplifier,
12゜13...Comparator, 14...Focus-on signal output terminal, 15...Pickup, 16...
・Speed detector, 17...speed control circuit, SW+, S
W2...Switch circuit.

Claims (1)

[Claims] means for starting the rotation of the optical disc at a first rotational speed lower than the steady rotational speed when the optical disk starts rotating; and a second rotational speed at which the optical disk is on the way to the first rotational speed. means for outputting a focus servo-on signal for turning on the focus servo; and a means for switching the drive voltage of the optical disk rotation motor when a focus lock signal is supplied from the focus servo to which the focus servo-on signal has been supplied. A rotation control device for an optical disc, comprising means for increasing the rotation speed to the steady rotation speed.