JPS6087475A - Head-part driving device of information device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention controls the movable part of the head of an optical tisf device to track a track using a tracking actuator, and also controls the track by a transfer device together with the tracking actuator. The present invention relates to a head driving device that can be transported.

<Prior art> In order to sequentially track a track of approximately 1 μm in diameter formed on a rotating disk over the entire circumference in a spiral manner, an optical disk device generally requires a tracking actuator with high gain and excellent frequency tracking characteristics, and a tracking actuator with excellent frequency tracking characteristics in a low frequency range. follow,
The structure is such that the optical head is moved all around the inner and outer peripheries and the near motors are operated simultaneously.

However, when movement in one direction is performed using two drive systems, the optical head is moved at high speed near the desired track position, and then the tracking servo is applied to the tracking actuator to move the optical head to the desired track position. When performing a search operation to reach , the tracking actuator vibrates due to the acceleration during acceleration and deceleration associated with the movement of the optical head, so a waiting time for the vibration to decay is required for the tracking servo to retract, which slows down the search process. Speeding up was hindered. Furthermore, if the amount of vibration of the tracking actuator is too large, there will be a problem in that the optical axis that enters the condensing lens of the optical head will be largely deviated, and the focus servo will also be deviated.

For this reason, the configuration shown in FIG. 1 is disclosed in the 1981 National Conference Lecture Proceedings of the Society for Knowledge and Child Communication, Page 5-81 (1210).

In other words, 1 is a semiconductor laser, and 2 is an OJ moving part of a head unit that focuses on the information surface of a disc 4 as a recording medium that is rotationally driven by a disc motor 5 and performs C stain removal and writing of information. A focusing lens 3 is a tracking actuator that adjusts the position of the focusing lens 2 so that the focusing lens 2 tracks the track formed on the disk 5, and a tracking actuator 3 is applied with a tracking actuator. 6 an optical head incorporating a condensing lens 2 and a tracking actuator 3, etc.; I a linear motor for transporting the entire optical head 6 over the entire inner and outer tracks; 8 a linear morph drive control circuit for controlling the drive of the linear motor 7; 9 is a speed detector for detecting the transport speed of the optical head 6;
Reference numeral 10 denotes an acceleration detection circuit that obtains an acceleration signal by differentiating the detection data of the speed detector 9. Reference numeral 11 drives and controls the tracking actuator 3 according to the acceleration signal obtained by the acceleration detection circuit 10 as well as the normal tracking servo. This is a tracking drive circuit.

In this conventional configuration, when the optical head 6 is transferred by the linear motor 7, the acceleration accompanying the transfer is inputted to the tracking drive circuit 11 via the speed detector 9 and the acceleration detection circuit 10, and the acceleration is As a result, the tracking drive circuit 11 works to suppress vibrations generated by the tracking actuator 3, so that the optical head 6
This makes it possible to suppress vibrations of the tracking actuator 3 that occur during the transfer of the tracking actuator 3.

, 1' However, since the conventional configuration described above requires the speed detector 9, the acceleration detection circuit 10, etc., the structure and circuit are complicated, and the cost is significantly increased.

On the other hand, it is also possible to optically detect the movement of the tracking actuator itself and configure a servo system that uses this detected amount as input to regulate the movement of the tracking actuator, but since a detection system is added in the same way as above, ,
The optical system is complicated, and the number of manufacturing steps is increased.

<Summary of the Invention> The present invention has been made in view of the above points, and provides a device that suppresses vibrations of a tracking actuator with a relatively inexpensive configuration and without providing a special detection system.

<Embodiment of the Invention> An embodiment of the present invention will be described below with reference to FIGS. 2 to 5. Incidentally, the same elements as in the conventional example are given the same reference numerals, and the explanation thereof will be omitted.

In the figure, 12 is a compensation circuit into which the drive current for driving the linear motor 7 output from the linear motor drive control circuit 8 is input, and the output thereof is input into the tracking drive circuit 11, and via the circuit 11, the compensation circuit 3 compensates for almost no vibration due to the movement of the optical head 6.

By the way, by using the drive current IM output from the linear motor drive control circuit 8 as an input variable, the movement amount XA of the tracking actuator 3 and the movement distance XM of the optical head 6 are calculated.
The block diagram in the case where the relative amount XA-XM of is used as the output variable is as shown in FIG. Here, KM is the proportional gain for converting the drive current IM into the force FM, GM is the transfer function for converting the force FM into the transfer amount XM, the transfer function of the Gc force compensation circuit 12, and the output of the KAU compensation circuit 12. Proportional gain for converting the signal into force FA acting on the tracking actuator 3; GA is the transfer function for converting the force FA into the movement amount xA of the tracking actuator 3 + GMA is the optical head; This is the transmission number m that represents the degree of employment transmitted to the amount of movement.

From this block diagram, XA=GA FA +GMA XM (1) = 4GA
GcIM+GMAXM (2) holds true.

This is it, the amount of movement XA of tracking actuator 3
and the relative amount of transport ff XM of the optical head 6 is
(KA GA Go +KM GM (GMA -1)
) IM (4) The transfer function G of the relative amount XAM to the drive current IM is G=KAGA Go +KMGM (GMA-1) (
5).

Therefore, no matter what drive current is output from the linear motor drive control circuit 8, the compensation circuit 12 is controlled by the transfer function C(
, is selected so that Ga=KMGM(1-GMA)/KAGA (6), then the above G becomes 0, and the vibration of the tracking actuator 3 generated by the movement of the optical spatula F6 is theoretically converted into heat. I can do it. Therefore, in the above embodiment, the error compensation circuit 12 has a transfer function GQ of (
6) It is configured to satisfy the formula.

To explain this using a specific example, since the relationship between the optical head 6 and the tracking actuator 3 is generally expressed by a dynamic model as shown in FIG. 4, the equation of motion is as follows.

mAxA×ηA (xA-xM)+kA(xA-XM)
= fA where mA is the mass of the tracking actuator 3, ηA is the viscous damping coefficient of the connection between the tracking actuator 3 and the optical head 6, kA is the spring constant of the connection, and fA is the tracking actuator 3 in time and space.
IM is the amount of movement of the optical head 6 in time and space, and XA is the tracking actuator 3 in time and space.
is the amount of movement.

Converting the above equation to Laplace space, pA=(mAs2+ηAs +kA)XA−(ηAs+
kA) XM and then XA becomes.

This is shi, GA, and GMA respectively. becomes.

Furthermore, the transfer function GM from the force FM of the linear motor 7 to the transfer tt -77MS-1-1c14 (1°
). Here, mm is the mass of the moving part of the linear motor 1, ηM is the viscous reduction coefficient of the external damping, and kM is the spring constant of the lead wire, etc.

Therefore, (6)? (8) f (9) , (10
) from the formula. Incidentally, this frequency characteristic is shown in FIG.

When using the compensation circuit 12 with such a transfer function Go,
The linear motor drive control circuit 8 also outputs a drive current to the linear motor 7, and the optical head 6 transfers the amount X.
Even if M acts as a forced displacement on the vibration system of the tracking actuator 3, the relative position between the optical head 6 and the tracking actuator 3 will not vibrate due to the compensation circuit 12 and the tracking actuator drive circuit 11 that receive the drive current as input. Since the force fA is applied to the tracking actuator 3 to prevent this, the relative position between the optical head 6 and the tracking actuator 3 can be controlled to a constant value.

In the above embodiment, the relative position between the optical head 6 and the tracking actuator 3 can be controlled to a constant value in all frequency ranges. Taking advantage of the fact that /2π is sufficiently high compared to the characteristic dynamic number /2π of the linear motor 7, the compensation circuit can have a gain adjustment circuit configuration in which the transfer function GQ is a proportional gain.

In this case, the frequency characteristic of the transfer function G of the relative position XAM to the drive current IM is shown by the solid line in FIG.

From this figure, it can be seen that during acceleration and deceleration of the linear motor I, which induces vibrations in the tracking actuator 3, vibrations of the tracking actuator 3 hardly occur.

Further, the compensation circuit may be configured so that its transfer function G□ has a first-order or higher bypass filter characteristic with a cutoff frequency p that is sufficiently higher than the natural frequency of the tracking actuator.

Furthermore, although the information device uses an optical disk as an example, it goes without saying that the present invention can also be applied to devices such as magnetic disks.

<Effects of the Invention> As explained above, according to the present invention, a tracking actuator for tracking a movable part of a head unit that exchanges information with a recording medium along a track formed on the recording medium is provided together with the head unit. In a head drive device of an information device configured to be able to transfer a sheet rack to a transfer device operated by a drive signal, the drive signal of the transfer device is input to a compensation circuit, and the output signal of the compensation circuit is tracked. Since it is configured to be used as an input signal for the actuator,
By simply adding a purely electronic compensation circuit, which is an inexpensive configuration, it is possible to suppress fluctuations in the relative position of the optical head and tracking actuator due to the movement of the optical head, and all of the conventional inconveniences can be eliminated. .

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a head drive device of a conventional optical disk device, FIG. 2 is a block diagram of a head drive device of an optical disk device according to an embodiment of the present invention, and FIG. 3 is a block diagram of the same as above. Figure 4 is a diagram showing the dynamic model of the trunking actuator section, Figure 5 is a frequency characteristic diagram of the compensation circuit used in the above, and Figure 6 is a diagram showing the frequency characteristics of the compensation circuit used in the above example. FIG. 3 is a frequency characteristic diagram of a transfer function of relative position to drive current. 2... Condensing lens 3... Tracking actuator 4... Disk 6... Optical head 7...
Linear motor 8...Linear motor drive control circuit 1
1...Tracking actuator drive circuit 12.
...Compensation circuit agent Masuo Oiwa (2 people) Figure 1 Figure 2 Figure 3 Figure 4 XM XA

Claims (3)

[Claims] (1) A tracking actuator that causes the movable part of the head section that exchanges information with the recording medium to follow the track formed on the recording medium is installed with a transfer device that operates together with the head section based on a drive signal. In a head drive device of an information device configured to be able to transport a truck,
A head drive device for an information device, characterized in that a drive signal of the transfer device is input to a compensation circuit, and an output signal of the compensation circuit is used as an input signal of a tracking actuator. (2) The head drive device for an information device according to claim 1, wherein the compensation circuit is a gain adjustment circuit with flat frequency characteristics. (3) The head driving device for an information device according to claim 1, wherein the compensation circuit is a bypass filter circuit having a cutoff frequency lower than the mechanical resonance frequency of the tracking actuator.