JPS6139939A - Tracking controller - Google Patents

Abstract

PURPOSE:To prevent a pickup from coming off a track by detecting it when a track error signal of a tracking means reaches an upper limit value or more to feed a slider of the pickup by each prescribed amount. CONSTITUTION:A part of the transmitted light of a polarized beam splitter 8 is received by track error detecting photodetectors 13, 14, the remaining light is received by focus detecting photodetectors 15, 16 to detect a shift to a track 11. An output signal of a differential amplifier 25 changes with a shift between the pickup and the track 11 on an optomagnetic disc 7 and given to an upper/ lower limit comparator 27. The upper/lower limit comparator 27 gives an output signal until a tack error signal reaches the lower voltage when the signal level becomes an upper limit voltage of feed a slider 17 and does not give an output signal until the voltage reaches again the upper limit voltage when the level of the error signal is 0V to stop the slider 17. Thus, the pickup does not come off the track.

Description

[Detailed Description of the Invention] (Technical Field) The present invention relates to a disk device such as a magneto-optical disk device□
The present invention relates to a tracking control device.

In a magneto-optical disk device, a magneto-optical disk is rotated at a constant speed, and a pickup is sent at a constant speed in a direction across a spiral track on the magneto-optical disk to record and reproduce information. In order to increase the information recording density of the magneto-optical disk, the rotation of the magneto-optical disk is made faster when recording and reproducing information on the inner side and slower when recording and reproducing information on the outer side, so that the linear velocity of the pickup with respect to the trunk remains constant. When the pickup was required to be sent at a constant speed across the spiral track, a problem occurred in which the pickup missed the track.

(Objective) An object of the present invention is to provide a tracking control device that can prevent pink-up from going off-track in a disk device.

(Structure) The present invention includes a tracking means in a disk device,
The apparatus includes a detection means for detecting that the track error signal has exceeded an upper limit value, and a feeding means for moving the slider of the pickup by a predetermined amount each time the detection means generates a detection signal. The tracking means detects the deviation of the pickup with respect to the spiral truss on the disk, generates a track error signal, and moves the objective lens on the pickup in response to the track error signal to cause the pickup to follow the track. Every time the track error signal exceeds the upper limit value, it is detected by the detection means and the feeder 9 slider is fed by a predetermined amount.

FIG. 2 shows a pickup in an example of a magneto-optical disk device to which the present invention is applied.

The laser beam emitted from the semiconductor laser 1 is made parallel by a coupling condenser 2, passes through a prism 3 and a half mirror 4, is reflected by a mirror 5, and is sent to a magneto-optical disk 7 via an objective lens 6. The light is focused as a light spot. The reflected light from the magneto-optical disk 7 is reflected by the mirror 5 via the objective lens 6, reflected by the half mirror 4, a part is reflected by the polarizing beam splitter 8, and the rest is transmitted. The reflected light from the polarized beam splinter 8 is received by a light receiving element 10 via a lens 9, and the information recorded on the track 11 on the magneto-optical disk 7 is obtained from this light receiving element 10. A portion of the transmitted light from the polarizing beam splitter 8 passes through the lens 12 and is received by a pair of track error detection light receiving elements 13.14, and the rest is received by a pair of focus detection light receiving elements 15.16. Light receiving element 1
3.14 is for detecting the deviation of the optical spot with respect to the trunk 11, and is arranged symmetrically above and below the optical axis. The focus detection light receiving elements 15 and 16 are arranged symmetrically on the left and right sides of the optical axis, and the focus adjustment device adjusts the focus by moving the objective lens 6 back and forth (up and down) according to the difference between the output signals of the light receiving elements 15 and 16. automatically.

The magneto-optical disk 7 has a spiral trunk groove 11, and is rotationally driven by a drive device so that the linear velocity with respect to the track of the pink amplifier is constant, thereby recording and reproducing information. The pick amplifier has the above optical system 1 on the slider 17.
As shown in FIG. 3, when the ball screw 19 is rotated by the feed motor 18, the slider 17 is moved to the guide member 20.
21 in the radial direction of the magneto-optical disk 7.

The spring 22 is used to remove bank cranes, and as shown in FIG.
The output signal is passed through amplifiers 23 and 24 to a differential amplifier 25.
There is a difference. The output signal of the differential amplifier 25 changes depending on the deviation between the pickup and the track 11 on the magneto-optical disk 7 (the deviation between the optical spot and the track 11), and is used as a track error signal by the driver 26 and the upper and lower limit comparison. It is output to the device 27. The driver 26 includes variable resistor VR1 amplifiers AI and A2 as shown in FIG.
, diodes DI, D2, transistors Ql, Q2, capacitor C1, resistors R1 to R11, etc., drive the track coil 28 by the track error signal.

The objective lens 6 is moved in the radial direction of the magneto-optical disk 7 by a track coil 28 and a spring, so that the light spot follows the track 11. Further, the upper/lower limit comparator 27 compares the track error signal with a preset upper limit voltage and lower limit voltage, and when the track error signal exceeds the upper limit voltage, sends an output signal to the gate 29 to open the gate 29. Therefore, the pulse from the oscillator 30 passes through the gate 29, and the motor driver 31 drives the feed motor 18 using the pulse from the gate 29 to move the slider 17 toward the outside of the magneto-optical disk 7, thereby reducing the tracking error signal. . Once the track error signal exceeds the upper limit voltage, the upper/lower limit comparator 27 outputs an output signal until it reaches the lower limit voltage to send the slider 17, and when the track error signal reaches the lower limit voltage, for example, Ov, it becomes higher than the upper limit voltage again. The output signal will not be output until the slider 1
Stop 7. In this case, the feed speed of the slider 17 is set to be faster than the moving speed of the objective lens 6 in the normal direction, and the feed of the slider 17 returns the objective lens 6 to the center position and the tracking error signal becomes Ov. The slider 19 stops moving.

A pink-up magneto-optical disk (track) like this
The pickup can be fed even if the linear velocity is constant.

Note that the present invention can also be applied to the case where the magneto-optical disk is rotated at a constant speed, in which case the pickup can follow the track no matter how the rotational speed of the magneto-optical disk is set.

Further, in the above embodiment, the slider may be moved by a set amount each time the track error signal exceeds the upper limit voltage. Further, the present invention can be similarly applied to optical disk devices.

(Effects) As described above, according to the present invention, the slider of the pick amplifier is moved by a predetermined amount each time the track error signal of the tracking means exceeds the upper limit value in the disk device.
It can prevent the pickup from running off the track.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a perspective view showing a pickup in an example of a magneto-optical disk device, FIG. 3 is a perspective view showing a feeding mechanism of the pickup, and FIG. FIG. 3 is a circuit diagram showing the driver of the above embodiment. 13.14... Light receiving element for track error detection, 18
...Feed motor, 25. Differential amplifier, 27. Upper and lower limit comparator, 28. Track coil. Figure 1 Figure 4 Figure 2 Figure %

Claims (1)

[Claims] In a disk device, a tracking means detects a deviation of a pickup with respect to a spiral track on a disk, generates a track error signal, and moves an objective lens on the pickup based on the track error signal to cause the pickup to follow the track on the disk. A tracking control device comprising: a detection means for detecting that the tracking error signal exceeds an upper limit value; and a feeding means for moving a slider of a pickup by a predetermined amount each time the detection means generates a detection signal.