JPH0215471A - Pickup moving velocity controller - Google Patents

Abstract

PURPOSE:To secure a desired servo band by processing a velocity detected signal by input-output behavioral characteristics corresponding to the transfer function of a driving means to drive a pickup in a direction orthogonal to a recording track and compensating the velocity detected signal. CONSTITUTION:The recorded information of a disk 1 is read by a pickup 2, and the output of the pickup 2 is supplied to a track crossing velocity detecting circuit 3. A motor driving circuit 8 drives a linear motor 9 and moves a slider 10 loaded with the pickup 2 in the radial of the disk 1. A driving current detected signal outputted from the motor driving circuit 8 is supplied through an equivalent filter 15 to a difference signal generating circuit 16. The equivalent filter 15 is set so that its transfer function can be approximately the same as that of the linear motor 9. An output Vo of the equivalent filter 15 passes through an amplifier 17, a velocity detected signal Vd through an amplifier 18 is subtracted from the Vo, and a difference signal output is passed through an HPF20 and added to the velocity detected signal Vd. Thus, the desired servo band can be secured.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to D RAW (Direct Read A
The present invention relates to a pickup moving speed control device in a disk recording and reproducing apparatus that reproduces recorded information on a recording disk such as a recording disk or records information on a recording disk.

BACKGROUND ART In a disk performance device, a pickup moving speed control device is essential in order to move the information reading point of the pickup to the recording position at high speed when regenerating recorded information on a recording disk or recording information. There is. As a conventional pickup moving speed control device, a device as shown in FIG. 4 is known. In the figure, recorded information on a disc 1 is read by a pickup 2. The output of the pickup 2 is supplied to a track crossing speed detection circuit 3. In the track crossing speed detection circuit 3, the output of the pickup 2 is amplified by the head amplifier 4 and then supplied to the tracking error signal generation circuit 5. The tracking error signal generation circuit 5 is configured to generate a tracking error signal according to the relative position of the information reading optical spot of the pickup 2 with respect to the recording track, for example, by a so-called sampled servo method. Regarding the sampled servo system, please refer to the patent application filed in 1986.
3-93882.

The tracking error signal output from the tracking error signal generation circuit 5 is supplied to a zero cross comparator 6, which compares the level of the tracking error signal with the zero level to form a pulse consisting of two positive signals according to the comparison result. . The output pulse of this zero cross comparator 6 is supplied to a frequency detection circuit 7. The frequency detection circuit 7 is configured to detect, for example, the inversion interval of the output pulse of the zero-cross comparator 6, and generate a signal having a level corresponding to this interval. The output of this frequency detection circuit 7 is supplied to the motor drive circuit 8 as a speed detection signal Vd.

The motor drive circuit 8 is composed of a linear motor or the like, which operates according to the level difference between the level of the speed detection signal Vd and a specified speed signal Va having a level corresponding to the specified speed supplied from a system controller (not shown) or the like. It is configured to drive a slider motor 9. The pickup 2 is driven by the linear motor 9 by this motor drive circuit 8.
A slider 10 carrying a slider 10 moves in the radial direction of the disk 1, and the relative speed of the information reading optical spot of the pickup 2 in the direction perpendicular to the track is controlled so as to match the designated speed.

In the track crossing speed detection circuit 3 having the above configuration, when the pickup 2 moves in the direction perpendicular to the track and the information reading optical spot crosses the recording track, the level of the tracking error signal becomes positive or negative with respect to the on-track level. The tracking error signal changes alternately in both directions and has a frequency corresponding to the track crossing speed, and the zero cross comparator 6 outputs a pulse as shown in FIG.

A signal having a level corresponding to the frequency of the output pulse of the zero-cross comparator 6 is the speed detection signal Vd which is the output of the track crossing speed detection circuit 3. The transfer function K(s) of this track crossing speed detection circuit 3 is expressed by the following equation.

1-exp(-sτ) Sτ K(s)-Kv exp (-) −
(1) Sτ 2 Here, Kv is speed detection sensitivity [v/m/see], τ
is the cross-track spacing [5 ecl.

The Bode diagram of this transfer function K(s) is as shown in FIG. 6, and as the track crossing speed becomes slower, the phase delay becomes larger. This is because as the track crossing speed becomes slower, the track crossing information becomes discrete.

As a result, the conventional pickup moving speed control device may not be able to obtain a desired servo band.

Summary of the Invention The present invention has been made in view of the above points, and includes:
It is an object of the present invention to provide a pickup moving speed control device that can sufficiently widen the servo band.

In order to achieve the above object, in a pickup moving speed control device according to the present invention, a signal processing means processes a drive signal with input/output characteristics corresponding to a transfer function of a drive means for driving the pickup in a direction perpendicular to the recording track. is provided, and the speed detection signal is compensated by the difference between the output of the signal processing means and the speed detection signal.

Embodiments Hereinafter, embodiments of the present invention will be described in detail with reference to FIGS. 1 to 3.

In FIG. 1, a disk 1, a pickup 2, a track crossing speed detection circuit 3, a motor drive circuit 8, a linear motor 9, and a slider 10 are connected in the same way as in the apparatus shown in FIG. However, in the motor drive circuit 8 in this example, the drive current I supplied to the beam near motor 9
A detection means for generating a drive current detection signal according to the current is built-in.

The drive current comparison signal output from the motor drive circuit 8 is supplied to the difference signal generation circuit 16 via the equivalent filter 15. The equivalent filter 15 is formed so that its transfer function is approximately equal to that of the linear motor 9. In the difference signal generation circuit 16, the output Vo of the equivalent filter 15 is supplied to a subtraction circuit 19 via an amplifier 17. The speed detection signal Vd output from the frequency detection circuit 7 is supplied to the subtraction circuit 19 via the amplifier 18. Subtraction circuit 1
9, the output of the amplifier 18 is subtracted from the output of the amplifier 17. The output Ve of the subtraction circuit 19 is supplied to an addition circuit 21 via a bypass filter 20, and is added and synthesized with the speed detection signal Vd.

The output of this adder circuit 21 is supplied to the slider control circuit 7.

The parts of the above configuration excluding the motor drive circuit 8 are as follows:
It can be represented by a block diagram as shown in FIG.

In the same figure, block B1 is a beam near motor 9, block B2 is a track crossing speed detection circuit 3, block B3 is
is the amplifier 18, block B4 is the bypass filter 20,
Block B5 corresponds to the equivalent filter 15, and block B6 corresponds to the amplifier 17. Also, the addition point P1 is the subtraction circuit 1
9. The addition point P2 corresponds to the addition circuit 21.

Transfer function G(S
) is expressed by the following formula.

L G(s)---(2) Also, the gains of amplifiers 17 and 18 are respectively Ka.

Kb, the transfer functions of blocks B3 and B6 are expressed as Ka and Kb, respectively.

Note that the transfer function Geq(s) of block Bs (equivalent filter 15) is approximately equal to the transfer function expressed by equation (2). Further, the transfer function K(s) of block B2 (track crossing speed detection circuit 3) is expressed by equation (1).

FIG. 3 is a vector diagram showing signals of each part of the device of FIG. 1. In FIG. 3, when the track crossing speed decreases and a phase delay occurs in the speed detection signal Vd, the speed detection signal Vd becomes a signal represented by a vector (Vd). In addition, the output V of the equivalent filter 15 is supplied with a drive current detection signal corresponding to the drive current ■ of the linear motor 9.
Since there is no phase delay in o, the output of amplifier 17 is
The signal is expressed as a vector (Kb·Vo).

Furthermore, the inverted signal of the output of the amplifier 18 that is subtracted from the output of the amplifier 17 in the subtraction circuit 19 is the vector (-
The result is a signal expressed as (Ka-Vd).

Therefore, the output Ve of the subtraction circuit 19 is the vector (-Ka
・Vd) and the vector (Kb-vo) are combined to produce a signal expressed by a vector (Ve).

By the way, while the output Vo of the equivalent filter 15 includes a DC component of the drive current I caused by the tilt of the device, etc., it does not include a component due to nonlinearity in the low range of the linear motor 9 and an eccentricity information component. Therefore, these unnecessary components will be mixed into the output Ve of the subtraction circuit 19.

However, these unnecessary components in the output Ve of the subtraction circuit 19 are removed by the bypass filter 20. The output of this bypass filter 20 is a vector (V
Vector (Ve・H) obtained by slightly advancing the phase of e)
(s)). Since the output of this bypass filter 20 is added and synthesized with the speed detection signal Vd by the adder circuit 21, the motor drive circuit 8 receives the phase signal obtained by combining the vector (vd) and the vector (Ve・H(s)). A signal represented by a vector (Vs) without delay is supplied, and the servo band can be made sufficiently wide.

In the above embodiment, the speed detection in the track-crossing speed detection circuit 3 was performed using a tracking error signal, but the track-crossing speed detection circuit 3
The speed detection may be performed using a 16-track count pulse generated in the sampled servo system, that is, a pulse that is inverted every time the information reading light spot moves by 16 tracks in the direction perpendicular to the tracks.

Effects of the Invention As detailed above, in the pickup moving speed control device according to the present invention, signal processing is performed to process the drive signal with input/output characteristics corresponding to the transfer function of the drive means for driving the pickup in a direction perpendicular to the recording track. Since the speed detection signal is compensated by the difference between the output of the signal processing means and the speed detection signal, the speed detection signal is compensated by a signal with no phase lag, and the speed detection signal is This makes it possible to suppress phase lag and secure a desired servo band.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a block diagram of a portion of the device shown in FIG.
3 is a vector diagram showing the signals of each part of the device shown in FIG. 1, FIG. 4 is a block diagram showing a conventional pickup moving speed control device, and FIG. The waveform diagram in FIG. 6 is a Bode diagram of the transfer function of the track crossing speed detection circuit 3. Explanation of symbols of main parts 2...Pickup 3...Track crossing speed detection circuit 8...
... Motor drive circuit 9 ... Linear motor 15 ... Filter 17.18 ... Amplifier 19 ... Subtraction circuit 20 ... Bypass filter 21... Addition circuit

Claims (1)

[Claims] a speed detection means for generating a speed detection signal according to a relative speed of the information reading point of the pickup in a direction perpendicular to the recording track according to an output signal of the pickup; and a driving means for driving the pickup in a direction perpendicular to the recording track. A pickup moving speed control device that controls the moving speed of an information reading point of the pickup in a direction perpendicular to the recording track by supplying a drive signal corresponding to the speed detection signal to the driving means, signal processing means for processing the drive signal with input/output characteristics corresponding to a transfer function of the drive means; and difference signal generation means for generating a difference signal according to the difference between the speed detection signal and the output of the signal processing means. and mixing means for mixing the difference signal with the speed detection signal.