JPH01184728A - Optical information recording and reproducing device - Google Patents

Abstract

PURPOSE:To prevent a tracking error signal from being disturbed and to correctly position an optical spot by detecting a defect on a tracking spot. CONSTITUTION:A difference between the maximum value Y2 of respective amplitude values of a reading signal for two tracking spots 104, 105 and a maximum values Y1 of respective amplitude values of a reading signal 102 for two preceding tracking spots 100, 101 is found out. When the difference is not included within an allowable range, the existence of a defect on the tracking spot 105 is decided and the reading signal 102 of the tracking spot 105 is inhibited to be used for the calculation of the tracking error signal. Even if a defect exists in the tracking spot, an optical spot can be correctly positioned without almost being disturbed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an optical information recording/reproducing apparatus, and more particularly to an optical information recording/reproducing apparatus using a disc having a tracking spoiler I-.

(Prior Art) In conventional optical information recording and reproducing devices, two methods of tracking a minute spot light for recording, reproducing, or erasing information are: (1) following a guide groove provided in advance on an optical disc; (2) Two or more tracking spots 1- are recorded in each of a plurality of servo information areas provided on an optical disk by being offset alternately in the radial direction of the disk, and the middle of the offset spots 1- is tracked. There are two methods -m-. These two techniques are known.

Ru.

One method that improves the latter is the sample servo method. Regarding this, for example, refer to the document "Format for
r 5-1/4 optical disk system
ems” (SPIEvol, 6950ptical M
ass Data Storage II pp, 23
9° 1986).

(Problem to be Solved by the Invention) Fig. 6 is an explanatory diagram of one of the servo areas of the nl'' rack and the (n+1) I- rack in the sample servo system. They are alternately offset in the disk radial direction from the track center 2.C is a clock spot located at the center of the 1-rack.

In the sample servo method, the difference between the maximum values of the amplitudes of the readout signals for servo slots 1 to 1 and 1 is used as a tracking error signal. The timing at which the maximum value of the amplitude of the read signal of the servo sub-board 1- is captured is created based on the read-out signal of the clock sub-board 1-.

For this reason, if there is a defect in the disk at the tracking slot 1-, the readout signal is disturbed, making it impossible to obtain the correct amount of 1~racking error and making it impossible to position the light spot correctly.

The present invention solves these problems. The purpose is to provide an optical information recording and reproducing device that can prevent a tracking error signal from being disturbed and correctly position a light spot by detecting a defect in the tracking slot 1-. .

(Means for Solving the Problems) The optical information recording/reproducing device of the present invention includes: a) concentrically or spirally disposed on the surface of the optical disc;
A plurality of servo information areas are arranged together with the data area, and a first spot and a second spot for tracking and one spot for clock are recorded in advance in the servo information area, 1-Ranking is performed by focusing a light source such as a semiconductor laser to a minute spot I and irradiating the optical disc to read out the tracking spot I and the clock spot, and recording, reproducing, or recording information. In an optical information recording and reproducing device that performs erasing, b) determining the maximum value of the amplitude of the readout signal of the first spot for tracking, and C) combining the maximum value and the amplitude of the readout signal of the first spot preceding the first spot. ~
determining the difference between the maximum value held among the maximum values of the amplitude of the readout signal of the first spot for racking; d) a predetermined first threshold and a second threshold; e) the error is greater than the first threshold and the second
f) further determine the maximum value of the amplitude of the readout signal of the second spot for tracking, and g) determine the maximum value and the amplitude of the read signal of the second spot preceding the second spot. !・Determine the difference between the maximum value of the amplitude of the readout signal of the second spot for racking and the maximum value held, and h) determine the predetermined first threshold value and second threshold value. , and the difference; i) only if the difference is greater than the first threshold and less than the second threshold; holding the maximum value of the amplitude of the readout signal of the spot and further the maximum value of the amplitude of the readout signal of the second spora j for tracking; k) the maximum value of the amplitude of the readout signal of the first spot for tracking; The method is characterized in that the difference between the maximum value and the maximum value of the held readout signal of the second spora l- is taken in as a tracking error signal to position the minute spot light.

(Embodiment) FIG. 1 is a block diagram of a tracking error signal generation circuit of an optical information recording/reproducing apparatus in an embodiment of the present invention.

Figure 2.3.4 is an explanatory diagram of the basic idea of the present invention. Figure 2 is a spot for 1 Heratsuking! ~100.1
Reproduction signal 102 when the reading light spot passes through the 1-rack center 103 when there is no defect at 01
& shows. The maximum value of the read signal amplitude of the spot 1oO is Xl, and the maximum value of the read signal amplitude of the spora h101 is Yl.

Figure 3 shows the tracking slots 1 to 1°O, 1 in Figure 2.
Tracking subbox that comes after 01 1-104.10
5, there is a large defect at 105, and the maximum value Y of the read signal amplitude of tracking sub-box I-105
2 is larger than Yl.

Figure 4 shows the tracking spot 100.10 in Figure 2.
Comes after 1! -Racking slot 1-1○6.10
This is a case where the maximum value Y3 of the readout signal amplitude of the tracking spot 1-IQ7 becomes smaller than Yl because the tracking spot 1-107 is missing among the tracking spots 1-IQ7. Usually free of defects.

The maximum value of the readout signal amplitude of the adjacent tracking subtitles does not change significantly.

FIG. 5 is a waveform explanatory diagram of FIG. 1. FIG. 1 and FIG. 5 will be explained together.

A readout signal 11 read out from the readout optical spot is amplified by an amplifier circuit 2, and high-frequency noise is removed by a lowpass filter 3 (a). Next, the peak detection circuit 4 detects the peak of the read signal (b), and the clock spot 1-
Only the pulse corresponding to the peak of PL is extracted by the clock extraction circuit 5 (,), and the pulse corresponding to the peak of
L circuit) 6 @PLL6 enters peak hold circuit 7.
8 reset 1-pulse and its hold timing signal d.

Create timing No. 43 for operating the sample and hold circuits 15 and 16. The beak bold circuit 7 extracts the maximum value (f) of the read signal corresponding to the leading tracking sub-box 1-.

The peak hold circuit 8 is used as a spot 1 for subsequent tracking.
The maximum value (g) of the read signal corresponding to - is extracted.

The sample and hold circuit 15.1G holds f and g at the rising edge of the timing signal j only when a predetermined condition described later is satisfied.

In the $5 figure, 29.30.32.33 is 1 to racking spot 1-131.34 is clock spot j-
It is. However, there is a defect at spot 33. 1 ~ Ranking spot 1-29.30.32.33
The maximum value of the amplitude of the readout equal sign corresponding to is A and B, respectively.
, C, D.

Here, the circuit operation will be described on the premise that the maximum values A and B of the jlA cap of the read signal corresponding to the tracking spot 1-29.30 are held in the sample and hold circuit. Therefore, sample and hold circuit i5
. It is required as. In this case, the trunking error signal is (A-B).

The minute spot light for readout is the tracking spot 3.
Before reaching 2.33, the outputs f and g of the peak hold circuits 7 and 8 are reset to 1 by the reset 1 pulse.

Next, the minute spot light for readout is applied to the tracking spot 1.
-32.When passing through 33, peak hold circuits 7 and 8
The outputs f and g become C and D, respectively.

The subtraction circuit 9 outputs the difference between the output of the sample hold circuit 15 and the output f of the peak hold circuit 7. That is n. Similarly, the subtraction circuit 10 outputs the difference between the output 1 of the sample hold circuit 16 and the output g of the peak hold circuit 7. That is 0.

The comparators 11 and 12 and the AND circuit 21 constitute a so-called window comparator.

Only when the difference signal n is higher than the first threshold voltage (Vl) 18 and lower than the second threshold voltage (V2) 17, the output of the AND circuit 21 becomes high.

1 to racking spot 32 have no defects,
The value of (A-C) becomes 71 or more and v2 or less, and the output p of the AND circuit 21 becomes high.

Similarly, the comparators 13 and 14 and the AND circuit 22 also constitute a window comparator.

Only when the difference signal 0 is greater than or equal to the first threshold voltage (Vl) of 20 and less than or equal to the second threshold voltage (V2) of 19, the output of the AND circuit 22 becomes high.

Unlike tracking spots 1 to 32, tracking spot 33 has a defect, and the (straight) of CB-D) is
Since it is 1 below, the output p of the AND circuit 21 becomes low.

Therefore, the output r of the AND circuit 23 becomes low.

Now, when the level of the control signal 27 is set to low, the output i of the OR circuit 24 becomes low, so the timing signal for operating the sample and hold circuits 15 and 16 is cut off by the AND circuit 25. For this reason, the sample hold circuit 15.16 is connected to the tracking spot 1-32.3.
The maximum values C and D of the amplitude of the read signal of No. 3 are not held, but the previous values A and B are held.

Therefore, (CD) does not become a tracking error signal, but (A-B) becomes a trunking error signal again. In this way, the tracking error signal is not disturbed due to defects on the racking spots 1 to 1.

Note that the control signal 27 has been described above. This is an operation prohibition signal for the defect detection circuit on the racking spot 1 to racking spot 1. When the control signal 27 is high, the output i of the OR circuit 24 is always high, so the holding operation is always performed at the rising edge of the timing signal output by the sample hold 6.

(Effects of the Invention) As described above, according to the present invention, the respective maximum values of the amplitudes of the readout signals of the two spots for tracking and the amplitudes of the readout signals of the two spots for the preceding 1-ranking If it is not within the allowable range, it is determined that there is a defect in the tracking spot 1-, and the readout signal of the tracking spot 1- is calculated as the tracking error. Since it is not used to calculate the signal ', even if there is a defect at l-racking spot 1-, the tracking error signal will not be disturbed in most cases and the light spot will be correctly positioned. continues to be.

Further, even if there is a defect in the tracking slot 1-, the trunking operates normally, so even if the number of defects on the disk increases due to deterioration over time, the tracking performance will hardly change. Therefore, the reliability of the system can be greatly improved.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a tracking error signal generation circuit of an optical information recording/reproducing apparatus according to the present invention. FIG. 2 shows the waveform of a defect-free 1~racking spot~ and its readout signal. Figures 3 and 4 show the defective tracking spot 1.
- and the waveform of its readout signal. FIG. 5 is an explanatory diagram of waveforms at each part of FIG. 1. FIG. 6 is an explanatory diagram of a servo area in a conventional sampling servo system. 9.10.26--Subtraction circuit 17.19-11 Second threshold voltage 18.20-11 First threshold voltage 29.30.32-m-Flaw-free tracking spot 33- m-defective tracking spot 1-31.
34-meter locking spot 1-or more lα Fig. 2 Fig. 3 Fig. 4 Fig. 5 Fig. 6

Claims (1)

[Claims] a) Concentrically or spirally on the surface of the optical disc,
A plurality of servo information areas are arranged together with the data area, and a first spot and a second spot for tracking and one spot for clock are recorded in advance in the servo information area, Optical information for recording, reproducing, or erasing information by performing tracking by focusing a light source such as a semiconductor laser into a minute spot light and irradiating the optical disc to read out the tracking spot and the clock spot. In the recording and reproducing apparatus, b) determining the maximum value of the amplitude of the readout signal of the first spot for tracking, and c) determining the maximum value and the amplitude of the first signal for tracking preceding the first spot. determining the difference from the maximum value held among the maximum values of the amplitude of the readout signal of the spot; d) comparing the difference with a predetermined first threshold value and a second threshold value; e) the difference is greater than the first threshold and the second
f) further determining the maximum value of the amplitude of the readout signal of the second spot for tracking, and g) combining the maximum value and the amplitude of the readout signal of the second spot for tracking. said second for tracking
h) Find the difference between the maximum value of the amplitude of the readout signal of the spot and the maximum value held, and h) Compare the difference with a predetermined first threshold value and a second threshold value. , i) only if the difference is larger than the first threshold and smaller than the second threshold; j) the maximum value of the amplitude of the readout signal of the first spot for tracking; ,
further retaining the maximum value of the amplitude of the read signal of the second spot for tracking; k) the maximum value of the read signal of the held first spot and the maximum value of the amplitude of the read signal of the held second spot; An optical information recording/reproducing apparatus characterized in that the difference between the readout signal and the maximum value is taken as a tracking error signal to position the minute spot light.