JPS58199470A - Jump pulse generator - Google Patents

Abstract

PURPOSE:To allow a disk read head to jump to an optional track securely by composing a jump pulse of an acceleration and a deceleration pulse and then superposing the displacement signal of an actuator on the jump pulse. CONSTITUTION:When a kick pulse A is outputted from a pulse oscillator 28, an acceleration signal B appears at the output of a flip-flop 29. The signal B is impressed to an AND gate 34 through a delay circuit 32 to generate a signal F. The signal F drives a clear driving circuit 35 and a brake pulse H is generated by a flip-flop 30. The acceleration pulse B and brake pulse H are supplied to a subtracter 31 for subtraction and a driving amplifier 26 impresses the jump pulse K to a tracking coil 10. The displacement voltage of the actuator is extracted by a low-pass filter 39 from the tracking signal D and impressed to the driving amplifier 26, which superposes it upon the jump pulse K.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides an optical information reading device such as a compact disc, in which a head that optically reads information on a disc moves from a track being tracked to an adjacent track or to any track. The object of this invention is to enable the head to be moved more reliably than before when it is moved by jumping, and is a further improvement on the jump pulse generator already filed by the same applicant. .

That is, when making the head jump, the width of the jump pulse is controlled according to the jump state, thereby ensuring the head jumps to the target track. However, in reality, any jump state In order to correspond to the acceleration and deceleration energies (
A balance must be maintained between the eccentricity of the disk (which is primarily a leaf spring that holds the actuator in its mechanical center) and the acceleration and deceleration energy generated by jump pulses. Since there are restrictions on the wire diameter of the tracking coil winding of the actuator that is actually constructed due to weight, characteristics, etc., it is not possible to precisely apply sufficient acceleration/deceleration voltage. Therefore, a current limiter is usually installed to limit the current. For this reason, the Jeanno-Grus is limited by this current limiter, and the waveform is often saturated.

In order to improve this point, the present invention maintains the performance of the current limiter of the actuator as before, and superimposes the displacement signal of the actuator on the jump pulse to generate acceleration energy and deceleration energy in order to perform a more reliable jump. In order to balance the above, one embodiment will be shown below along with the drawings.

As shown in FIG. 1, when the driver smoke 1 rotates, the actuator support 7 is moved by the gear 2.3.4, and the actuator is moved so that the objective lens 11 is mechanically centered by the support spring 9 as shown in FIG. It is configured to be held and slightly displaced in the radial direction of the disk by the tracking coil 10. As shown in Figure 3,
The disk 12 is rotated by the motor 15, and the information on the disk is read by the optical pickup P, and the head unloader 7
``Focus on optical pickup P from 13.

The signal is fed back through a tracking and traverse servo circuit 16, and is controlled by a CLV circuit 17 so that the disk 12 rotates at a constant speed relative to the pickup in synchronization with a synchronization signal on the disk. Matahead Z'n7
A signal S is outputted from the output of the signal 13 to the demodulation circuit 18.

FIG. 4 shows a block diagram of the tracking servo circuit in the servo circuit 16 in the apparatus configured as described above.

The signal from the pickup P is regenerated by the photodetector 20 and separated into the information signal 19 and the tracking error signal by the separation circuit 21. The tracking error signal is applied to the drive amplifier 26 via the phase correction circuit 24 and the adder 25, and the current Tracking coil 10 via limiter 27
and performs feedback control. When the kick command 41 is applied, a kick pulse is generated from the 7XQ pulse oscillator 28 in synchronization with the tracking signal.

Hereinafter, the generation of the jump 7XQ pulse according to the present invention will be explained along with the waveforms of each part in FIG. Pulse oscillator 28
When kick pulse A is output from flip-flop 2
An acceleration signal B appears at the output terminal Q of the circuit 9, and the signal B is applied to the delay circuit (which may also be an integration circuit) 32 to output a waveform C, which exceeds the threshold voltage e8 of the A-book gate 34, and the tracking waveform The setting voltage e1
When the voltage becomes very low and the output E of the comparator 33 becomes high level, a signal F is generated from the AND dirt 34 only during that period, and this indicates that when the tracking signal crosses the set voltage el, the track crossing has not been completed. This prevents the acceleration pulse from stopping. The signal F is the clear drive circuit 3 of the flip-flop 29.
5 to output a waveform G, and at the same time the acceleration pulse is stopped, a brake pulse QKH is generated from the output of the flip-flop 30. On the other hand, the tracking signal is added to an advance circuit (a differentiating circuit may be used) 36 to output a waveform, and after crossing the track, it is converted into a waveform that is displaced in one direction. , signal J is output from the comparator 37 only when the voltage of the waveform generator is higher than the set voltage e2 (5), and the seven lip-flops 30 are cleared at the time interval d, and the brake pulse H is stopped.

The acceleration/-, 0 pulse B and brake pulse H obtained as above are subtracted by the subtracter 31, and a jump pulse K is applied to the tracking coil 10 by the drive amplifier 26 via the adder 25 to cause the tracking coil to jump.

In Figure 5, L is the moving speed of the actuator p
M indicates the state of displacement when jumping from track e to target track d.

Also, when switch sl falls to contact a, the arbitrary set voltage e2
An adder 40 adds an eccentric signal obtained via the low-frequency F wave generator 38 or a voltage corresponding to the positional deviation from the mechanical center of the actuator to the tracking signal, and this and the tracking signal 3 are added to the comparator 3.
7, the stopping timing of the acceleration pulse and the brake pulse is changed according to the eccentricity of the disk and the state of the actuator at the time of the jump, so that a reliable jump can be performed. However, as mentioned above, in reality, (6) the current limiter 27 is set to a low value due to the performance of the actuator, and as a result, the jump i4)res cannot supply a sufficiently high voltage, so the acceleration pulse and brake pulse In some cases, it may not be possible to control the pulse width alone. The current waveform applied to an actual tracking coil is often saturated.

Therefore, in the present invention, even when the jump pulse is saturated, in order to balance the acceleration energy and deceleration energy by controlling the offset of the acceleration and brake pulses, as shown in FIG. Displacement voltage with respect to the center
Take out the tracking coil drive amplifier 2 by
6 and superimpose it on the jump pulse to control the balance between acceleration energy and deceleration energy in accordance with the displacement of the actuator.

In Figure 4, 22 represents the traverse signal using the formula The low-frequency E wave device 23 is a drive amplifier.

As shown in FIG. 6, waveform P is a displacement signal of the actuator, Q is a jump pulse, and R is a control signal waveform. As is clear from the figure, the voltages of the acceleration pulse and deceleration pulse are the same at Q, but at Q' the displacement of the actuator is downward and the actuator swings in the deceleration direction, so the leaf spring It is desirable that the deceleration pulse voltage be higher than in the case of Q because a force is generated to return to Q. Therefore, when a control signal such as R is superimposed with a pulse of Q', during a jump, the acceleration voltage is low and the brake voltage is high. On the other hand, during the non-jump period, the voltage R is reduced by servody depending on the tracking signal, so the actual displacement of the actuator is minute and does not pose a problem. Furthermore, during the jump period, the tracking servo is once off, so the control voltage R does not drop by the servo gain. This situation is shown in FIG. 7, where ps is a demodulated information signal whose level drops during the jump period.

The voltage when the servo is open is T with the signal R, and the voltage is attenuated from T to R during the period when the scissor is closed (not jumping). The jump pulse Q' is limited to the voltage eL by the emitter and has an offset R, and during the period when the signal is lowered due to the jump, it becomes a composite waveform with the offset shown by the broken line T.

In addition, there are conventional cases in which the deceleration direction relies only on the return force of the plate/gun, but instead of the restoring force of the mechanical plate spring, which has a lot of variation (it also changes greatly due to humidity), the brake is applied by an electronic circuit. It goes without saying that it is more reliable to apply a pulse and further control the pulse width and voltage.

As described above, according to the present invention, the jump pulse is composed of an acceleration pulse and a deceleration pulse, and by superimposing the actuator displacement signal on this jump pulse, the head can be reliably jumped to an arbitrary track.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the actuator transfer device of the optical disc reading device, Fig. 2 is a diagram showing the actuator, Fig. 3 is an overall configuration diagram of the optical disc reading device, and Fig. 4 is a plot (9) of the tracking servo circuit. Figure 5 is a waveform diagram of each part in Figure 4, Figure 6 is
FIG. 7 is a jump/'e pulse waveform diagram. 10... Tracking coil, 12... Objective lens, 12... Disk, 13... Head amplifier, 16
... Servo circuit, 20... Photodetector, 21... Separation circuit, 22... Low-pass filter, 23... Drive amplifier, 24.00 Phase correction circuit, 25...・Addition circuit, 26
...Drive amplifier, 27...Current limiter-128.
...Pulse oscillator, 29.30...Flip-flop, 31...Subtractor, 32...Delay circuit, 35...
Clear drive circuit, 36... Differential circuit, 38.39
...Low frequency wave generator. Figure 5 Figure 6 Figure 7

Claims (1)

[Claims] In a device equipped with an actuator that slightly displaces a head that reads information recorded on a disk, and a traverse that is equipped with the actuator and moves at high speed,
Jump No. 1, characterized in that a pulse for causing the head to jump from the current track to an adjacent track is composed of an acceleration pulse and a brake pulse, and a displacement signal of the actuator is superimposed on the acceleration pulse and the brake pulse. Lux generator.