JP2646168B2 - Optical system controller for disk drive - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical system controller for a disk drive.

[0002]

2. Description of the Related Art In a disk device such as a CD player, a tracking servo system is provided for following a track of a disk, and a focus servo system is provided for focusing an optical system. In some cases, a correct tracking error signal and focus error signal cannot be obtained, and there is a problem that servo becomes impossible. For this reason, in the conventional disk drive, a defect such as detection of a defect of the RF signal is detected, and a tracking and focusing coil voltage during the passage of the defect is held at a voltage immediately before the defect, and a configuration such as switching of a filter constant is adopted. This was adopted to prevent following an erroneous servo error signal, thereby preventing abnormal noise and skipping of sound.

[0003]

However, even if the above-mentioned pre-value holding process is performed, if the width of the flaw is long in the track direction, the amount of deviation of the trajectory during the passage of the flaw increases, and the servo can be pulled in. In some cases, the focus servo system and the tracking servo system cannot return to the just-focused and just-tracked positions after passing through the scratches. As a result, there is a problem that abnormal noise and skipping occur. An object of the present invention is to solve the above-mentioned problems of the conventional technology.

[0004]

In order to achieve the above object, an optical system control device for a disk drive according to the present invention comprises: an optical system for controlling an optical path for a disk; an optical system driving means;
An optical system control means for controlling the movement of the optical system so that information can be recorded and / or reproduced on a disk as a medium using the optical system; a flaw detection means for detecting flaws on the disc; Holding means for holding an input signal to the optical system driving means after a lapse of a predetermined time from completion of flaw detection, and inputting to the optical system driving means when a flaw is detected by the flaw detecting means thereafter Switching control means for switching from the output of the optical system control means to the output of the holding means.

[0005]

When the flaw detecting means detects a flaw on the disk, an input signal to the optical system driving means after a predetermined time has elapsed is held by the holding means. Thereafter, by the flaw detection means
When a flaw is detected, the input to the optical system driving means is switched from the output of the optical system control means to the output of the holding means by the switching control means.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. Information recorded on a disk X driven by a spindle 15 is read optically through an objective lens 14 provided in the pickup 1 and converted into an electric signal, and then processed through an RF amplifier 2 for signal processing. A predetermined signal processing is applied by the unit 3 and the speaker 5 is connected via the D / A converter 4.
It is constituted so that it is converted into voice and outputted.

The pickup 1 is subjected to tracking servo control by a driver section 13 so as to follow the tracks of the disk X. Similarly, the objective lens 14 is also subjected to focus servo control by the driver unit 13 so as to focus on the pit P of the disk X. That is, the error signal of the focus servo is sent to the servo unit 11 via the focus error amplifier 6, and the driver unit 13 drives the objective lens 14 to correct the error. Similarly, a tracking error signal is sent to the servo unit 11 via the tracking error amplifier 7, and the driver unit 13 is configured to drive the pickup 1 so as to correct the error.

The output from the RF amplifier 2 is also input to the flaw detection circuit 8, and when the output of the RF amplifier 2 falls below a predetermined reference voltage, it is determined that there is a flaw.
The flaw detection signal activates the timer 9 to measure a predetermined time. FIG. 3 shows the relationship between the output of the RF amplifier 2, the output of the flaw detection circuit 8 , and the output of the timer 9. The output of the flaw detection circuit 8 rises when the level of the RF amplifier 2 falls, and the timer 9 rises for a predetermined time by the fall of the output of the flaw detection circuit 8.

A sample / hold circuit 10 and a changeover switch 12 are interposed between the servo section 11 and the driver section 13. As shown in FIG.
0 samples the output from the servo unit 11 while the output of the timer 9 is present, and then holds the output. The changeover switch 12 is for selectively connecting the servo unit 11 and the sample-and-hold circuit 10 to the driver unit 13. Normally, the switch unit 12 is connected to the b-contact to connect the driver unit 13 to the servo unit 11. I have. FIG.
When there is a signal from the flaw detection circuit 8 as shown in FIG. The servo control is executed by the output from the CPU. Reference numeral 20 denotes a microcomputer configured to execute overall control of the above-described configuration.

As shown in FIG. 3, when a flaw is detected for the first time, for example, a previous hold voltage is supplied to the driver unit 13. At this time, the fall of the output of the flaw detection circuit 8 causes an error after passing through the flaw. Signal (focus error signal and / or tracking error signal; the same applies hereinafter)
The circuit is held by the hold circuit 10 (point A), and when the next flaw is detected, the changeover switch 12 is set to the sample / hold circuit 10
Side, and supplies the held voltage to the driver unit 13 (point A), based on which the servo control is executed.

Next, the operation will be described on the assumption that there is a flaw D as shown in FIG. The flaw D extends over the flaw D1 on the inner track and the flaw D2 on the next track, and its width in the track direction is longer than the flaw D2 on the outer circumference. In the conventional configuration, if there is a long flaw in the track direction like the flaw D2, the amount of deviation of the trajectory becomes large during the passage of the flaw, and there is a problem that the track exceeds the servo pull-in range. Such problems can be solved. Although the focus servo will be described below, the same operation is performed in the case of the tracking servo. Disc X
When a portion having no flaw is reproduced, the RF signal is supplied from the RF amplifier 2 to the flaw detection circuit 8 as shown in a section A of FIG.
Has been entered. When the pickup 1 arrives at the flaw D1, the laser light from the pickup 1 does not normally reflect back, and the level of the RF signal from the RF amplifier 2 decreases. This is section B, and the flaw detection circuit 8 outputs a flaw detection signal while detecting the level decrease. The changeover switch 12 is simultaneously switched to the a side by the H output of the flaw detection circuit 8, and the previous value hold voltage is supplied to the driver unit 13, for example, as in the conventional case. The timer 9 is started for Tt by the fall of the flaw detection circuit 8, and the focus error signal from the focus error amplifier 6 after passing through the flaw is sampled at the point A by the sample and hold circuit 10, and this value is held. This Tt time may be arbitrarily set, but needs to be sufficiently shorter than the time T at which the focus servo ends re-pulling after passing through the flaw.

During the time T , the relative distance shifted from the just focus position in the section B during the passage of the wound is drawn into the just focus position, and the operation returns to the normal servo operation. Next, when it comes to the position of the flaw D2, the changeover switch 12 is switched to the terminal a side by the same operation, and the voltage held in the sample and hold circuit 10 at the point A is supplied to the driver unit 13. This voltage is more ideal than the previous value hold voltage and the offset voltage of the amplifier, so even after a long section B, the trajectory does not deviate greatly, and it is redrawn after passing through the wound Becomes possible. Even at the time of the second wound passage, the sample / hold circuit 10 executes sampling by the output of the timer 9 and supplies this voltage to the driver unit 13 at the time of the next wound passage.

As described above, according to the above configuration, the trajectory of the second and subsequent flaws is not largely shifted,
Good focus and tracking servo can be realized. Therefore, if the first flaw is a long flaw in the track direction, there is a possibility of sound skipping or the like. However, if the first flaw is started from a small flaw as shown in FIG. Since the position of the objective lens 14 is corrected,
Then, even if the scratches become large, sound skipping and the like are effectively prevented.

In the case of a single flaw as shown in FIG. 2, the shape of the end face of the flaw and the reflectivity of the flaw surface are the same from the inner circumferential side to the outer circumferential side track. These are all different. Therefore, the value held after passing through the wound is desirably used when passing through the same wound,
For this purpose, a plurality of sample and hold circuits 10 are provided, each sample and hold circuit 10 is made to correspond to each of the scratches detected during the rotation of the disk X1, and a common hold value is used for the same scratch. It is desirable. More specifically, each time a flaw is detected, the sample and hold is sequentially performed from the first sample and hold circuit 10, and when one rotation of the disc X is detected by detecting a track number or the like, the process returns to the first sample and hold circuit 10, and This can be realized by associating each sample with each sample and hold circuit 10. At this time, for example, if the number of scratches detected during the rotation of the disc X1 is larger than the number N of the sample-and-hold circuits 10, after all the sample-and-hold circuits 10 sample and hold, they pass through other scratches. It is desirable to adopt a configuration in which no hold is performed even if the hold is performed.

When only one sample and hold circuit 10 is provided, if a plurality of scratches are detected during the rotation of the disk X1, the sample and hold circuit 10 performs a sample and hold operation after passing through another scratch. It is desirable to configure so as not to perform this. The above operation can be realized by the microcomputer 20.

[0016]

As described above, the optical system control apparatus for a disk drive according to the present invention comprises an optical system for controlling an optical path for a disk, an optical system driving means, and a disk as a medium using the optical system. Optical system control means for controlling the movement of the optical system so that information can be recorded and / or reproduced; flaw detection means for detecting flaws on the disc; and a predetermined time after completion of flaw detection by the flaw detection means. holding means for holding an input signal to the optical system driving means, thereafter the flaw detection
Switching control means for switching the input to the optical system driving means from the output of the optical system control means to the output of the holding means when a flaw is detected by the means,
Even if there is a long scratch or the like in the track direction on the disc, it is possible to suppress the occurrence of abnormal noise, skipping sound, and the like.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention.

FIG. 2 is an explanatory diagram showing an example of a scratch on a disk.

FIG. 3 is a timing chart for explaining the operation of one embodiment of the present invention.

[Explanation of symbols]

1: pickup, 2: RF amplifier, 3: signal processing unit,
4: D / A converter, 5: speaker, 6: focus error amplifier, 7: tracking error amplifier, 8: flaw detection circuit, 9: timer, 10: sample and hold circuit, 1
1: servo unit, 12: changeover switch, 13: driver unit, 14: objective lens, 15: spindle, 20: microcomputer.

Claims (5)

(57) [Claims] 1. An optical system for controlling an optical path with respect to a disk, an optical system driving unit, and a control of the movement of the optical system so that information can be recorded and / or reproduced using the disk as a medium using the optical system. an optical system control means for a flaw detection means for detecting a flaw of the disk, and holding means for holding the input signal after flaw detection completion because該傷detecting means to the optical system driving means after a predetermined time, thereafter Switching control means for switching the input to the optical system driving means from the output of the optical system control means to the output of the holding means when a flaw is detected by the flaw detection means. Optical system controller. Wherein a said holding means is a plurality, the holding means and the plurality of, when a plurality of scratches in the rotating disc 1 is detected, the optical system after a predetermined time between elapsed after the flaw detection 2. The optical system control device according to claim 1, wherein input signals to the drive unit are sequentially held, and the switching control unit sequentially switches to one output of the plurality of holding units when each flaw is detected. 3. If the number of scratches during one rotation of the disk exceeds the number of the holding means, the holding means does not hold the input signal for the scratches exceeding the number of the holding means. An optical system control device for a disk device according to claim 1 or 2. 4. The optical system is an objective lens, the optical system driving means is an objective lens driving means for moving the objective lens in the direction of its optical axis , and the optical system control means is that the focal point of the objective lens is 4. The optical system control device for a disk device according to claim 1, wherein the optical system control device is an objective lens control unit that controls the objective lens driving unit so as to match an information recording surface of the disk. 5. The optical system is a pickup having an objective lens, the optical system driving means is a pickup driving means for moving the pickup in a direction between tracks on a disk, and the optical system control means is a pickup. The optical system control device for a disk device according to claim 1, wherein the device is a pickup control unit that controls the pickup driving unit so as to follow a track of the disk.