JPH0744882A - Device for adjusting optimal focusing bias voltage for optical disk drive - Google Patents

Abstract

PURPOSE:To easily and surely adjust an optimal bias voltage by calculating the optimal bias voltage from both focusing bias voltages in which the same jitter value is obtained in the both side areas of the insensitive zone area of the characteristic of a jitter value. CONSTITUTION:By monitoring a measured jitter value by means of a jitter value indicating meter and turning on a switch 15 while boosting a focusing bias voltage, a focusing bias voltage for the jitter value in one area of the insensitive zone of the characteristic curve of jitter value-focusing bias voltage value is held in a focusing bias voltage holder 13. By successively boosting the bias voltage, a bias voltage becoming the same jitter value as that of the other area after passing through the insensitive area is held in a focusing bias holder 14. The optimal focusing bias voltage being the average value of these both held bias voltages is calculated in an optimal focusing bias voltage arithmetic device 17 and the optimal bias voltage adjustment is easily and surely performed through a voltage comparator 18 and a displayer 19.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optimum focus bias voltage adjusting device for an optical disk drive, and more particularly to an optimum focus bias voltage adjusting device for an optical disk drive for reproducing an optical disk such as a magneto-optical disk.

[0002]

2. Description of the Related Art In optical disk drive devices such as MD players and magneto-optical drives, there are variations in the characteristics of individual device components, so it is important to make initial adjustments to the device characteristics before shipment. Among the initial adjustments, the focus bias voltage is superimposed on the focus signal in order to set the focusing state in which the light emitted from the light emitting element such as the laser diode can be irradiated onto the optical disc surface in the focused state. Adjusted to.

FIG. 4 shows a basic configuration of an optical disk drive device. An optical disk 21 is mounted on the optical disk drive device 2, and an optical pickup 23 driven by an actuator 22 performs light irradiation and reflected light reception operations. Done. The reflected light signal from the optical pickup 23 is RF
It is amplified by the amplifier 24 and output as an RF signal. Further, the RF signal from the RF amplifier 24 is supplied to the focus servo control circuit 25, and the obtained focus control signal for the focus operation is sent to the optical pickup 23 to perform the autofocus operation.

On the other hand, as described above, since the individual components of the optical disk drive device (for example, the actuator 22 and the optical pickup 23) have characteristic variations, the characteristics are within the focus range required for the autofocus operation. Adjustments and settings to accommodate

Conventionally, this adjustment and setting are performed by the focus bias voltage adjustment unit 251 provided in the focus servo control circuit 25. The focus bias voltage adjusting unit 251 generates a focus bias voltage for compensating for a shift in the focus operation caused by the characteristic variations of the components, and outputs the focus bias voltage so as to be superimposed on the focus control signal. The value of the focus bias voltage is usually adjusted by the volume.

To set the focus bias voltage to the optimum value, the jitter measuring device 3 for measuring the jitter based on the RF signal output from the RF amplifier 24 is used. The jitter measuring device 3 inputs the RF signal from the reference optical disc into the comparator and measures the blur amount of the pulse width which is the output of the comparator as the jitter value. The focus bias voltage is set so that the jitter value is minimized. It

FIG. 5 shows the relationship between the focus bias voltage and the jitter value. The characteristic A shows the change in the jitter value of the CD disc, and the focus bias voltage that minimizes the jitter value is within a narrow range called a dead zone where the change in the jitter value is very small.

[0008]

As described above, the adjustment of the focus bias voltage in the conventional optimum focus bias voltage adjusting device for the optical disk drive is performed by the variation of the pulse width (jitter value) obtained by the jitter measuring device.
The focus bias voltage is set so that

However, when the optical disk is a magneto-optical disk, the relationship between the jitter value and the focus bias voltage becomes as shown by the characteristic curve B in FIG. 5, and the width of the dead zone becomes remarkably wide. With the measurement resolution of the jitter measuring instrument, it was extremely difficult to change the focus bias voltage to obtain the minimum jitter value, and it was difficult to set the optimum focus bias voltage.

Therefore, an object of the present invention is to provide an optimum focus bias voltage adjusting device for an optical disk drive in which the optimum focus bias voltage can be easily set even for a magneto-optical disk.

[0011]

In order to solve the above-mentioned problems, an optimum focus bias voltage adjusting apparatus for an optical disk drive according to the present invention adjusts an RF signal from an optical pickup of the optical disk drive apparatus and a focus bias voltage. A focus bias voltage signal from a detector, and a jitter measuring means for measuring a jitter value depending on the focus bias voltage from the RF signal; and a change in the jitter value obtained by the jitter measuring means with respect to the focus bias voltage. A detection unit that detects two focus bias voltages that exhibit large jitter values that are substantially the same outside the small dead zone region;
And an optimum voltage calculation means for outputting a voltage determined based on one focus bias voltage as an optimum focus bias voltage.

[0012]

According to the present invention, two focus bias voltages that can obtain the same jitter value are obtained in both side regions outside the dead band region in the jitter value characteristic showing the relationship between the jitter value and the focus bias voltage, and the two obtained focus bias voltages are obtained. The optimum focus bias voltage is obtained and set based on the voltage.

[0013]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of an optimum focus bias voltage adjusting device for an optical disk drive according to the present invention. In the present embodiment, the RF signal from the RF amplifier 24 of the optical disk drive device 2 (same configuration as FIG. 4) as shown in FIG. 2 and the focus bias voltage from the focus bias voltage adjusting unit 251 of the focus servo control circuit 25 are used. An optimum focus bias voltage is obtained by the optimum focus bias voltage adjusting device 1 (FIG. 1) which receives and.

Referring to FIG. 1, the RF signal is input to a jitter measuring section 11 having the same function as that of the conventional jitter measuring device 3, and the obtained jitter value is indicated by the indicating meter 12. On the other hand, the focus bias voltage is input to the focus bias voltage holders 13 and 14. The focus bias voltage holders 13 and 14 hold the input focus bias voltage and output it as holding voltage signals VA and VB in response to the ON operation of the holding switches 15 and 16 provided correspondingly. Holding switches 15 and 1
The ON operation of 6 is performed as follows by a manual operation of the operator.

FIG. 3 shows the relationship between the jitter value and the focus bias voltage when a magneto-optical disk is used. Figure 5
As described with reference to, the width of the dead zone in this case is C
It is remarkably wider than the case of the D disc, and it is difficult to set the optimum focus bias voltage by the conventional method.

In this embodiment, the operator visually confirms the indicator meter 12 and confirms that the jitter value is large outside the dead zone JA.
The holding switch 15 is turned on at the timing indicated by. Next, when the focus bias voltage is increased, the dead band region is entered, but when the focus bias voltage is further increased, the dead band region is exited and a jitter value JB substantially equal to the jitter value JA is obtained. Therefore, the holding switch 16 is turned on at this timing. Let As a result, in response to the ON operation of the holding switches 15 and 16, holding voltages VA and VB are obtained from the focus bias voltage holders 13 and 14, and are supplied to the optimum focus bias voltage calculator 17. The optimum focus bias voltage calculator 17 obtains the average voltage (VA + VB) / 2 of the supplied holding voltages VA and VB as the optimum focus bias voltage and outputs it.

The voltage comparator 18 compares this optimum focus bias voltage with the input focus bias voltage from the focus bias voltage adjusting section 251, and when both voltages match, the display 19 indicates that. Is done. The focus bias voltage from the focus bias voltage adjuster 251 that the operator confirms the display on the display 19 becomes the optimum focus bias voltage.

In the above embodiment, it is needless to say that the confirmation of two focus bias voltages having a large jitter value outside the dead zone region and having the same jitter value can be performed electrically instead of visually by the operator. Further, the optimum focus bias voltage need not be determined by the average voltage of the above two focus bias voltages.
It may be determined based on one focus bias voltage.

[0019]

As described above, the optimum focus bias voltage adjusting apparatus for an optical disk drive according to the present invention has the same jitter in both side regions outside the dead zone in the jitter value characteristic showing the relationship between the jitter value and the focus bias voltage. Since the focus bias voltage that gives a value is obtained and the optimum focus bias voltage is obtained and set based on the obtained focus bias voltage, the dead zone is not affected and the optimum focus bias voltage is always obtained.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of an optimum focus bias voltage adjustment device for an optical disc drive according to the present invention.

FIG. 2 is a configuration diagram of an optical disk drive device in the present embodiment.

FIG. 3 is a diagram showing a relationship between a jitter value and a focus bias voltage when a magneto-optical disk is used.

FIG. 4 is a basic configuration diagram of a conventional optical disk drive device.

FIG. 5 is a diagram showing a relationship between a focus bias voltage and a jitter value.

[Explanation of symbols]

 1 Optimum Focus Bias Voltage Regulator 2 Optical Disc Drive Device 3 Jitter Measuring Device 11 Jitter Measuring Unit 12 Indicator Meter 13, 14 Focus Bias Voltage Holder 15, 16 Holding Switch 17 Optimal Focus Bias Voltage Calculator 18 Voltage Comparator 19 Display 21 Optical disc 22 Actuator 23 Optical pickup 24 RF amplifier 25 Focus servo control circuit 251 Focus bias voltage adjustment unit

Claims (1)

[Claims] 1. A jitter value dependent on the focus bias voltage is input from the RF signal by inputting an RF signal from an optical pickup of an optical disk drive device and a focus bias voltage signal from an adjuster that adjusts the focus bias voltage. A jitter measuring means for measuring; and a detecting means for detecting two focus bias voltages showing a large jitter value which is substantially the same outside the dead zone where the change of the jitter value obtained by the jitter measuring means with respect to the focus bias voltage is small. An optimum focus bias voltage adjusting device for an optical disk drive, comprising: an optimum voltage calculating unit that outputs a voltage determined based on the two detected focus bias voltages as an optimum focus bias voltage.