JP2542493Y2 - Optical disk flaw detection circuit - 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 disk flaw detecting circuit in an optical disk player capable of reproducing both optical disks, video disks and compact disks.

[0002]

2. Description of the Related Art An optical disk player capable of reproducing both conventional video disks and compact disks.
The optical disk flaw detection circuit in the first embodiment is configured to detect an optical disk flaw when a signal responsive to light reflected from the optical disk falls below a predetermined level.

[Problems to be solved by the invention]

However, in the above-described conventional optical disk flaw detection circuit, the flaw detection sensitivity is fixed between a video disk and a compact disk, so that optimum flaw detection cannot be performed for each type of disk. was there. SUMMARY OF THE INVENTION An object of the present invention is to provide an optical disk flaw detection circuit which can switch the flaw detection sensitivity in accordance with the type of an optical disk to be reproduced and thus solves the conventional problems.

[Means for Solving the Problems]

An optical disk flaw detection circuit according to the present invention uses an optical disk flaw detection circuit in an optical disk player capable of reproducing both a video disk and a compact disk for four minutes after receiving light reflected from the optical disk.
The added signal level obtained by adding the output signals of the split diode
A voltage dividing circuit for applying a voltage,
Comparing means for comparing the force signal level with the optical signal to be reproduced.
Selectively switch the voltage dividing ratio of the voltage dividing circuit according to the type of disk.
A flaw detection sensitivity switching means for replacement is provided.

[0005] According to the optical disc defect detection circuit of the present invention described above, the optical disk is in the case of the compact disc in the case of the video disk being reproduced, anti from the optical disk
The sum of the output signals of the four-divided diodes
The voltage dividing ratio of the voltage dividing circuit that divides the calculated signal level is the flaw detection sensitivity.
Switching is selectively performed by the switching means, and
Divided voltage circuit with selectively divided signal level and divided voltage ratio
The output signal level of the road is compared by the comparing means.
For this reason, an optimum flaw detection can be performed according to the type of the optical disc to be reproduced .

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to embodiments. FIG. 1 is a block diagram showing a configuration of an embodiment of the present invention. The flaw detection circuit 10 includes a comparator 1 composed of an operational amplifier, and a comparator 1 (hereinafter, referred to as an addition signal) which is a signal obtained by adding output signals of a four-division diode that receives reflected light from an optical disk.
A resistor R1 applied to the non-inverting input terminal of the comparator 1 and a voltage dividing circuit for dividing the addition signal are configured, and the divided voltage is applied to the inverted input terminal of the comparator 1 in parallel with the resistors R2, R3, and R3. The resistor R2 and the resistor R3 constitute a integrating circuit, and the transistor R1 is selectively connected in parallel with the resistor R3 to the resistor R4 to control the flaw detection sensitivity. The transistor Q1 is turned on and off by a switching signal output according to the type of the optical disc to be reproduced, that is, when the reproduced optical disc is a video disc or a compact disc, and the connection and disconnection of the resistor R4 are performed. The flaw sensitivity is switched by the above control.

On the other hand, a focus error signal is supplied to a peak hold circuit 11 via a transistor Q2.
The peak hold circuit 11 includes a voltage follower 2 and a resistor R.
5 and a capacitor C2, and the transistor Q2 is controlled to be in an off state during a period in which a flaw is detected by the output of the flaw detection circuit 10 to hold a focus error signal. is there. Tracking error
The signal is applied to the peak hold circuit 1 via the transistor Q3.
2 and the peak hold circuit 12 is
The transistor Q3 is turned off during a period in which a flaw is detected by the output of the flaw detection circuit 10, and the transistor Q3 is turned off.
It is configured to hold the tracking error signal.

In one embodiment of the present invention constructed as described above, the added signal is a voltage proportional to the amount of light reflected from the optical disk, and is a voltage of a predetermined level in a portion where there is no flaw on the optical disk. In the flaw portion of the optical disk, the level of the addition signal decreases and becomes a level approaching zero. The addition signal is input to the non-inverting terminal of the comparator 1 as it is, and the voltage obtained by dividing the addition signal by the resistors R2 and R3 and integrating by the capacitor C1 is applied to the inverting input terminal of the comparator 1. In a portion having no flaw, as shown in FIG. 2, the level of the addition signal is higher than the threshold level, the output of the flaw detection circuit 10 is negative potential, and it is detected that there is no flaw, and the transistors Q2 and Q3 are turned on. The focus error signal and the tracking error signal are output via peak hold circuits 11 and 12.

At the flaw portion, the added signal level decreases as shown in FIG. 2 and falls below the threshold level.
The output of the flaw detection circuit 10 changes from a negative potential to a positive potential, the transistors Q2 and Q3 are turned off, and the focus error signal and the tracking error signal are peak-held in the peak-hold circuit. The average value of the focus error signal and the average value of the tracking signal are output from the peak hold circuits 11 and 12, respectively.

Here, the switching signal causes the transistor Q
1 to the on state, the resistance R3 is connected to the resistance R3.
4 are connected in parallel, and when the transistor Q1 is off, the voltage dividing ratio of the resistors R2 and R3, which determine the threshold level of the comparator 1, is:
The voltage dividing ratio is reduced by the combined resistance of the resistor R4 and the resistor R4 connected in parallel to the resistor R2 and the resistor R3, and the threshold level shown by the one-dot chain line in FIG. 2 is reduced to the threshold level shown by the two-dot chain line. As described above, the flaw detection sensitivity is switched by switching the threshold level by the on / off control of the transistor Q1. Therefore, for example, when the playback optical disc is a video disc, the transistor is turned on and controlled by the switching signal, and when the playback optical disc is a compact disc,
By controlling the transistor to the off state by the switching signal, flaw detection can be performed with the optimum flaw detection sensitivity for the reproduced optical disc. Further, in the above-described embodiment, the case where the number of switching circuits is one is illustrated, but a plurality of switching circuits may be provided.

[0011]

[Effect of the Invention] As described above , the optical disk flaw of the present invention
According to the detection circuit, an optical disk in the case of the compact disc in the case of the video disk being reproduced, an optical disc
The output signal of the 4-division diode that receives the reflected light
The voltage dividing ratio of the voltage dividing circuit that divides the added signal level is
Selective switching by flaw detection sensitivity switching means, before
The level at which the division ratio is selectively switched with the addition signal level
The output signal level of the voltage circuit is compared with the comparing means.
Therefore, optimum flaw detection can be performed according to the type of the optical disc to be reproduced, and there is an effect that the flaw detection performance for various flaws is improved.

[Brief description of the drawings]

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

FIG. 2 is a level comparison diagram showing an addition signal level and a threshold level for explaining the operation of the embodiment of the present invention;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Comparator 2 and 3 Voltage follower 10 Flaw detection circuit 11 and 12 Peak hold circuit

Claims (1)

(57) [Scope of request for utility model registration] 1. A disc flaw detection circuit in a video disk and compact disk both reproducible optical disc player an optical disc, from the optical disk
The output signal of the quadrant diode receiving the reflected light was added.
A voltage dividing circuit for dividing the level of the addition signal;
Comparing means for comparing the output signal level of the voltage divider circuit with the output voltage level
And the voltage dividing circuit according to the type of the optical disc to be reproduced.
An optical disc flaw detection circuit comprising flaw detection sensitivity switching means for selectively switching a partial pressure ratio .