JPS60101779A - Recording and reproducing device - Google Patents

Abstract

PURPOSE:To improve the positioning precision of the 2nd tracking control means which has a wide movable range without increasing a gain by superposing an AC signal with a specific amplitude upon the driving signal of the 2nd tracking control means. CONSTITUTION:A recording and reproducing device is brought under the tracking control of the 2nd tracking control means 12 which uses a motor 6, screw 5, etc., and has the wide movable range and the 1st tracking control means 11 which uses an actuator driving means 9, etc., for a head actuator and a narrow movable range. The AC signal with the amplitude smaller than the movable range of the means 11 is superposed upon the driving signal by the means 12 through an oscillator 13 to improve the tracking precision through the means 12 without increasing the gain even when the screw 5 is loose and when there is the dead zone of the motor 6. Consequently, the tracking control is performed stably.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a recording and reproducing device for reading or writing information from an information I-rack on a record carrier.

Conventional configurations and their problems In optical video discs, compact disc players, or magnetic discs with high-density recording, the relative error between the head and the information track is required to be on the order of knob microns. Therefore, stable tracking control was essential.

When performing such tracking control, in order to widen the tracking control band and minimize steady-state errors,
First, the first dragging control vA1 means is used to make the head follow the information track within the movable range, and the second tracking 11011 means is used to move the entire pickup so that the head does not deviate from the movable range. many. A conventional example of such a tracking control means will be explained below based on the drawings.

FIG. 1 shows a conventional example of racking control means 1 of a recording/reproducing apparatus using the above method. 1 is an information track, 2 is a head, 3 is a head actuator, 4 is a pickup, 5 is a screw, 6 is a motor, 7 is a compensation means, 8
9 is a low-pass filter, 9 is an actuator drive means, 10 is a motor drive means, 11 is a first tracking control means,
12 is a second control means. The pickup 4 reads or writes information from the information track 1, and the compensation means 7 receives the tracking error signal and detects a relative position error between the head 2 and the information track 1 and outputs a tracking error signal. The actuator drive signal is output after applying high-frequency compensation to prevent pulse oscillation and low-frequency compensation to compensate for lack of gain in the low frequency range. The actuator drive means 9 drives the head actuator 3 in accordance with the actuator drive signal to cancel the position error. However, as described above, the compensation means 7, the actuator drive means 9 and the head actuator 3
When tracking control is performed only by the first tracking control means 11 consisting of It gets out of control. By the way, the range of movement of the head of a disc player is often only a few millimeters at most, so in order to widen the range of movement, the second 1-shoes 4:
The control means 12 is used. This second tracking control means 12 is composed of a screw screw 5, a motor 6, a low-pass filter 8, and a motor drive means 1o.The low-pass filter 8 extracts the low-frequency component of the tracking error signal and drives the motor. Outputs a signal. The motor drive means 10 moves the motor 6 by 1 degree in accordance with the motor drive signal.The rotation of the motor 6 is transmitted to the pickup 4 by the screw 5, and the pickup 4 is moved so that the head is always near the movable center 4 degrees. Ribs.

Therefore, the second 1 to racking III control means 12 c
There has been a phenomenon in which force is not transmitted to the pickup through the screw 5 when the motor drive signal is small due to friction and friction caused by the engagement U of the 1-screw 5, a dead zone of the motor 6, etc.

For this reason, the positioning accuracy of the second tracking control becomes poor, and the first tracking control means 11 may move beyond the movable range and deviate from the IC0, and even if it does not exceed the movable range, the first tracking control means This method has the disadvantage that it is susceptible to external disturbances such as scratches on the record carrier because the load is large and a large steady-state error remains. Note that when the gain is increased to improve the positioning accuracy of the second tracking control means 12, the second trunking control means 12 oscillates due to I9 friction of the screw, variations in play in engagement, and offset voltage of the circuit. The device would sometimes run out of control or run out of control, resulting in unstable operation.

OBJECTS OF THE INVENTION An object of the present invention is to improve the positioning accuracy of the second tracking control means without increasing the gain, and to provide a recording/reproducing apparatus that can perform stable tracking control.

Structure of the Invention The recording and reproducing apparatus of the present invention includes a pickup that reads information from an information track on a record carrier and detects a relative positional error between the head and the information track, and a movable pickup that moves the head in accordance with the positional error. A first tracking control means having a narrow range and a second tracking control means having a wide possible Wh range for moving the pickup in a direction intersecting (orthogonal to) the information track due to the position error, and , a second tracking control is performed by superimposing an AC signal on the drive signal of the second racking control means and making the amplitude of the pickup caused by the AC signal smaller than the movable range of the first tracking control means. The system is characterized by improving the positioning accuracy of the system without increasing the gain and realizing stable tracking control.

Description of examples Hereinafter, one embodiment of the present invention will be described based on the drawings.

FIG. 2 shows a recording/reproducing apparatus according to the present invention.

Components having the same functions as those in FIG. 1 are given the same reference numerals and their explanations will be omitted.

The first tracking control means 11 is as described above, and here, the second tracking control means 1
The difference from FIG. 1 is that an oscillator 13 is provided at 2 and the output thereof is input to motor drive means 10. Oscillator 1
3 gives minute rotational vibrations of appropriate amplitude to the screw 5, which is added to the motor drive signal in the motor drive means 10, causing the motor 6 to make minute rotational vibrations, while moving the pickup 4 and the head 2 to approximately the movable center.] Move it closer.

The reason why the positioning accuracy of the second tracking control means 12 is improved by this configuration will be explained in comparison with the conventional example.

The mechanism for moving the pickup 4 in the second tracking control means 12 shown in FIG. 1 includes J8! There is a rub, play or dead zone. Therefore, when the drive signal is small, the pickup 4 does not move at all. Once the drive signal becomes large and the pickup 4 starts moving, the static friction that has existed up until now turns into dynamic friction and the pickup 4 becomes too easy to control, making control difficult.

On the other hand, in the second tracking control means 12 shown in FIG. 2, the mechanism for moving the pickup 4 is slightly vibrated by superimposing an AC signal on the drive signal, so the friction is only slightly reduced. Noue becomes zero. This mechanism will be explained in more detail using the characteristic diagram shown in FIG.

FIG. 3A shows the relationship between the drive signal and the transmitted torque before the AC signal is superimposed on the drive signal, and FIG. 3B shows the relationship between the drive signal and the transmitted torque after the AC signal is superimposed. As shown in Figure 3, when the drive signal is near zero and there is a dead zone coming from friction and the machine 414, if an AC signal is superimposed, the vibration will be greater than the width of the dead zone, resulting in the characteristics as shown in Figure 3 B, and the dead zone is removed, and even for a minute drive signal, the torque corresponding to that signal portion is immediately increased by 1:1. Therefore, only a small amount of gain is required without moving the pickup 4. Furthermore, the play and dead zone that exist in the meshing V of the motor 6 and the screw 5 can be eliminated by setting the vibration peak so as to exceed the play and dead zone. The above-mentioned vibrations are simultaneously transmitted to the head 2 and increase the 1-racking error, but by setting the gain of the first tracking control means 11 sufficiently large, it can be suppressed to a value that does not pose a problem.

Here, if the frequency of the oscillator 13 is set within the second 1~racking band, the play in the meshing of the screw 5,
The minute vibration excited above the dead zone of the motor 6 is caused by the (interval loop gain +1) of the second tracking ailJ control means 12.
It is possible to apply the minimum necessary microvibration to the screw thread 5.

Furthermore, if the above-mentioned 1-to-1 ring error signal contains many of the same frequency components as the above-mentioned alternating current signal, they overlap with the above-mentioned alternating current signal components and generate unnecessary amplitude.

In this case, on the contrary, it is sufficient to sufficiently attenuate the same frequency components as the AC signal using the low-pass filter 8, and then add an AC signal of an appropriate amplitude to the signal. The oscillator 13 may be of any waveform as long as it has the necessary amplitude, such as a sine wave, a triangular wave, or a rectangular wave. Also, it is effective even when the period is not constant, such as the white M tone. Regarding the frequency of the AC signal, the band of the second i-racking control means (
By setting the loop gain to a frequency within 1), the positioning error can be improved without giving unnecessary vibrations, and even if the frequency is outside the band, a C change can be expected compared to 1ξ.

For convenience of explanation, the explanation has been given by taking as an example the pick-up movement 15 ml: 4 to 96 and another 414 using the screw 5, but there are other types such as t and iii.

Further, the oscillator 13 does not need to be installed separately if there is another AC 13 source that can be used; for example, a commercial AC power source can be used. .

In the above embodiment, the low-pass filter No. 8 is 1-4 filters 1. n
The low frequency component of the difference signal is extracted and the motor drive signal is output, and the motor 6 is prevented from being supplied with power in an unnecessary band [1] Although it has the effect of preventing saturation of the motor drive circuit, it may be omitted.

Recording of the present invention as described in the detailed description of the invention 1-1-J, Rudo,
By superimposing an AC signal on the drive signal in the second tracking control means, the positioning error of the second ranking control means can be reduced without increasing the gain, and the positioning error of the second ranking control means can be reduced without increasing the gain. It can lighten the burden. In addition, by making the vibration of the pickup caused by superimposing the amplitude of the AC signal smaller than the movable range of the first racking control means, the vibration of the pickup can be adjusted to the first racking control means without any problem. A small suppressor is created and a stable 1-racking Ri! 7j3 that performs l 611 is possible.

[Brief explanation of the drawing]

Fig. 1 (14 diagram of 1 - racking control means of a conventional recording/reproducing apparatus; Fig. 2; 14 diagram of 1 - racking control means of a recording/reproducing apparatus in an embodiment of the present invention; !
Fig. 53 (The characteristic diagram of the drive signal and Butsuji torque shown in Fig. 2 is not shown.・7-ri, 9...
Akuji J. Ata driving means, 10... Ata driving means, 11...
・First 1-ranking control means, 12...Second 1
~Racking control means, 13...Oscillator agent Yoshihiro Moriki

Claims (1)

[Scope of Claims] 1. A pickup that reads information from the information track h\ on the record carrier and detects a positional error of about 3 inches relative to the head and the information track, and moves the head according to the positional error. h) First racking a with narrow range of motion
.
This AC signal (9
The above-mentioned pickpock caused by the issue? A recording/reproducing device in which a knob amplitude is made smaller than a movable range of a first tracking control means. 2. Claim 1, characterized in that the frequency of the AC signal is selected within the band of the 29th tracking control means.
The recording/reproducing device described in Section 1.