JPS63201921A - Signal reader - Google Patents

Abstract

PURPOSE:To increase a gain at the time of signal reproduction so as to improve the quality of a reproduced signal and to remove noise which occurs due to flaw on a disk by generating plural peripheral direction bit strings in a radius direction with leaving a space. CONSTITUTION:A titled device has a disk body 12 in which plural peripheral direction bit strings are generated along the radius direction with leaving a space, and one side detecting means and an other side detecting means detect the positions of the bit strings on the disk, whereby outputs from the one side and the other side detection means are respectively branched and given to first and second subtraction means. In the first subtraction means, the output of the other detection means is subtracted from the output of the one side detection means, and in the second subtraction means, the phase of the outputs of the one side and the other side detection means are respectively converted by 180 deg. and are inputted, whereby the output of the one side detection means is subtracted from the other side detection means. Thus, a having amplified reading output can be obtained if there are no scars on the disk body, and the reading output which becomes '0' level in a section having the influence of the flaw can be obtained if there is the flaw.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a signal reading device, and more particularly, to a signal reading device that is provided in an optical disk reproducing device so that detection light can accurately trace a pit row formed on a disk. The present invention relates to a signal reading device suitable for use in tracking servo mechanisms and the like.

FIG. 6 is a block diagram showing the electrical configuration of a tracking error signal detection circuit 30 using a typical prior art three-beam system. The light beams generated from the optical pickup include a main beam 31 and a first sub-beam 3 as shown in FIG.
The reflected light beams are divided into three beams, ie, the second ml beam 33 and the second ml beam 33, and are irradiated onto the disk 34, and these reflected lights are respectively incident on the main light detector n35 and the two sub light detectors 36 and 37.

The main beam 31 is a pit row 3 formed on a disk 34.
8 is read, this is converted into an electric signal by the main light detection section 35, and digital data is reproduced by a demodulation circuit (not shown). On the other hand, the outputs from the two sub-light detection sections 36 and 37 are respectively given to a subtraction circuit 39, where a subtraction process is performed. As a result, from the subtraction circuit 39, the pit row 3
A tracking error signal corresponding to the deviation of the main beam 31 from the main beam 8 is output. The tracking error signal thus output is given to an F-racking servo circuit (not shown), and the deviation of the main beam 31 is corrected based on the error signal.

In a disk recording/reproducing apparatus using such a tracking error signal detection circuit 30, when vibration is applied from the outside, for example, the main beam 3
1 may deviate from the pit row 38. Therefore, in order to suppress the deviation of the main beam 31 due to such vibrations, it is necessary to set the gain of the above-mentioned roughing effect signal to a large value.

On the other hand, when there is a scratch on the disk 34, for example, when the first and second sub-beams 32, 33 pass over the scratch, the tracking error signal is disturbed. Therefore, in order to suppress the disturbance of the tracking error signal due to the influence of such scratches, it is necessary to set the gain of the tracking error signal as small as possible.

Conventionally, because of these conflicting setting conditions, the gain of the troughing servo error signal was
I had set it to an intermediate level of Ift.

Problems to be Solved by the Invention However, in order to realize tracking servo with desired accuracy, the gain of the tracking error signal must be set above a certain level.
When the sub beams 32 and 33 pass through a scratch on the disk 34, the disturbance appearing in the tracking error signal cannot be effectively suppressed, and abnormal situations such as optical pickup malfunctions and track jumps caused by this disturbance can occur. It was not possible to eliminate the occurrence.

An object of the present invention is to solve the above-mentioned problems, increase the gain during signal reproduction, and improve the quality of the reproduced signal.
It is an object of the present invention to provide a signal reading device capable of removing noise generated due to scratches on a disk.

Means for Solving the Problems The present invention provides a disk body in which pit rows are formed along the circumferential direction, and a plurality of circumferential bit rows are formed at intervals in the radial direction; detecting means for detecting positions on the disk body separated in the radial direction by a distance of half the radial arrangement pitch of the pit rows, and an output of each detecting means as an input; and the output of the other detection means is subtracted from the output of one detection means mi
subtracting means; second subtracting means for subtracting the output of one of the detecting means from the output of the other detecting means; and interposed between each detecting means and the second subtracting means, converting the phase of the output of the detecting means. A signal reading device characterized in that it includes a phase conversion means and an addition means for adding each output of the first and second subtraction means.

According to the present invention, the position of the pit row on the disk body is detected by one detection means and the other detection means, and the outputs from one and the other detection means are branched and sent to the first and second subtraction means, respectively. Given. In the fjs1 subtraction means, the output of the other detection means is subtracted from the output of the one detection means, and in the second subtraction means, the phases of the outputs of the one detection means and the other detection means are both converted by 180° and input, and the output of the other detection means is inputted. On the other hand, the output of the detection means is determined from the output of r1. be done.

The outputs from the two subtraction means obtained in this way are:
If there are no scratches on the disc body, they will be in the same phase. That is, since the one and other force detection means detect the position on the disk body at a distance radially separated by half the radial arrangement pitch of the pit row, these two outputs are out of phase with each other by 180 degrees. . Further, the output of the 12 subtraction means is the subtraction of the output of one detection means whose phase has also been converted by 180 degrees from the output of the other detection means whose phase has been converted by 180 degrees. Therefore, the output of the second subtraction means has the same phase as the subtraction of the output of the other detection means from the output of the first detection means, which is the output of the first subtraction means, and these two outputs of the same phase are added and amplified by the addition means. The output of this adding means is given to other electric circuits as a read output obtained by detecting and reading the position on the disk body.

On the other hand, if there is a scratch on the disk body, the outputs from the first and second subtracting means are out of phase by 180 degrees in the section affected by the scratch. Therefore, in the above period, the outputs of the first and second subtracting means are added by the adding means and are canceled out, so that the output level becomes close to the θ level.

In this way, in the signal reading device according to the present invention, if there are no scratches on the disk body, an amplified readout output is obtained, and if there are scratches, the signal readout output is zero in the section affected by the scratches. A reading output close to the level can be obtained.

Embodiment FIG. 1 is a diagram showing the electrical configuration of a tracking error signal detection circuit 1 which is an embodiment of the present invention. The tracking error signal output circuit 1 includes a main light detection section 2 and two Il.
The output of the sub-detection section 3 is given to the non-inverting input terminal of the operational amplifier 5 via one resistor R1, R2, and the other is a capacitor C1, The signal is applied to the inverting input terminal of the operational amplifier 6 via the amplifier 7, the detector 9, the capacitor C3, and the upstream resistor R5, respectively, in this order. Further, the output of the sub-detection section 4 is applied to the inverting input terminal of the operational amplifier 5 via the resistor R3, while
0, a capacitor C4, a resistor R7, and a resistor R8, respectively, in this order, to the non-inverting input terminal of the operational amplifier 6.

The output of the operational term unit 5 is applied to the inverting input terminal via the resistor R4, and a negative feedback differential amplifier is configured by the resistors R1, R2, R3, and R4. On the other hand, the output of the operational amplifier n6 is also applied to the inverting input terminal via the resistor R6, and a negative feedback differential amplifier is constituted by the resistors R5, R6, R7, and R8. The respective outputs of such operational amplifiers 5 and 6 are applied to a connection point A, which is an adding means, via resistors R9 and RIO, and a tracking error signal, which will be described later, is output from this connection point A.

Here, the tracking error signal detection circuit 1 shown in FIG.
Before explaining the operation, the basic operation related to the sub-beam irradiated from the optical pickup will be explained with reference to FIGS. 2 and 3.

A sub-beam 11 emitted from the optical pickup is reflected on the disk 12 and enters, for example, the sub-detection section 3. In the sub-detector n3, the sub-beam 11 reflected from the disk 12 is converted into an electrical signal and output, and a tracking error signal is formed based on this output. Therefore, when the sub beam 11 crosses the pit row 13 on the disk 12 as shown in FIG. If we take the displacement in the radial direction, we get Figure @2 (2
) A waveform like the one shown is obtained. That is, pit row 13
Most of the sub-beam 11 irradiated onto the pit row 13
The amount of reflected light decreases. Therefore, when the sub beam 11 is on the pit row 13, the output voltage from the sub detection section 3 decreases.

Further, as shown in FIG. 3 (3), when the sub-light beam 11 scans over the pit row 13 by the rotation of the disk 12, the sub-beam 11 sequentially moves over the pit row 13 along the direction of the stroke. As the irradiation continues, the output voltage from the sub-detection section 3 has a waveform as shown in FIG. 4 (4).

Referring to Figure 3, when the sub beam 11 irradiates the plurality of pit rows 13 formed on the disk 12 while crossing in the direction of arrow A as shown in Fig. 1 (1), the sub beam 11 Since each pit in the pit row 13 is read, if the radial displacement of the sub-beam 11 is plotted on the horizontal axis, a waveform as shown in FIG. 2 (2) is obtained. Furthermore, when the sub-beam 11 is irradiated onto the rotating disk 12, the output of the sub-light detection section 3 contains a high frequency component accompanying the circulation of the disk 12, as shown in FIG. 4(4). The amplitude of this high-frequency component is extremely small compared to the waveform shown in FIG. Become.

In this way, the two waveforms shown in FIG. 1 (3) and FIG. As a composite wave, a waveform as shown in FIG. 2 (2) is obtained.

Next, the operation of the tracking error signal detection circuit 1 of this embodiment will be explained with reference to the diagram Ij44.

In this embodiment, a laser beam generated from an optical pickup as a tracking servo means is used as a main beam 16,
A 3-beam system is used in which the disk 12 is irradiated with the beam divided into a first TI4 beam 17 and a second sub-beam 18.

The main beam 16, the first sub-beam 17 and the t142 sub-beam 18 are the two sub-lights detected by the main light detection section 2 respectively.
1si 4, where it is converted into an electrical signal. The output from the main light detection section 2 is given to a demodulation circuit (not shown) and demodulated. The output from the sub-light detection section 3 is applied to a non-inverting input terminal of an operational amplifier 5, and is also applied to a capacitor C1.

The output of the flash detection section 4 is applied to an inverting input terminal of an operational amplifier 5, and is also applied to a capacitor C2.

Therefore, when the three beams scan the disk 12 rotating in the direction of arrow B as shown in FIG. 4(1), the output voltages output to the connection points 21 and 22 are If we take the radial displacements of the first and second II beams 17 and 18 on the disk 12, we obtain the following figures (
2) and (3) waveforms as shown in the figure are obtained. In the waveforms shown in Figures (2) and (3), the waveforms that are shifted by half a wavelength from each other are the first and
7 and 18 are irradiated to positions on the disk 12 that are separated in the radial direction by a distance that is half the radial pitch of each pit row 13, as shown in FIG.

Note that the above two outputs actually have a high frequency component added thereto as shown in Figure 3 (2), but the amplitude of this high frequency component is smaller than the low frequency component shown in Figure 3 (3). Since this is extremely small, this is ignored and only the low frequency component is shown in FIG. 2 (2).

Figure 4 (2) and (3) obtained in this way
When the two illustrated outputs are input to the non-inverting input terminal and the inverting input terminal of the operational amplifier n5, the operational amplifier 5 constitutes a differential amplifier, so the output 11
The above two outputs are subtracted to obtain a waveform as shown in (4) of the same figure.

On the other hand, the output from the sub-light detection section 3.4 given to the two capacitors CI and C2 is
, C2 removes the low frequency components corresponding to the output shown in FIG. 3 (3), and extracts only the high frequency components corresponding to the output shown in FIG. 3 (4), which are applied to the amplifier 7.8. In amplifier 7.8 said two capacitors CI.

The high frequency component extracted by C2 is amplified, and the outputs al and a2 are as shown in (5) and (5) in the same figure, respectively.
6) A waveform as shown is obtained. These two outputs a
l and a2 are envelope-detected by detectors 9 and 10 (see (7) and (8) in the same figure), and are connected to the non-inverting input of the operational amplifier 6 via two capacitors C3 and C4 and two resistors R5 and R7. terminal and inverting input terminal, respectively. Since this operational amplifier 6 constitutes a differential amplifier as described above, its output 12 has a waveform as shown in FIG. 9 (9).

Outputs i1 and i2 from the two operational amplifiers 5.6 thus obtained are applied to connection point A via resistors R9 and RlO, respectively. At this connection point A, the above two outputs are added, so the output E is the same figure (1
0) As shown in the figure, a waveform in which the output 11 from the operational amplifier 5 is amplified is obtained, and this is given to the servo drive means (not shown) as a tracking error signal.
Tracking servo is realized.

Next, a tracking error signal generated when there is a scratch on the disk 12 will be explained with reference to the fjS5 diagram.

For example, when there is a scratch 23 on the rotating disk 12 as shown in FIG. 5(1) and a part of the digital information is missing, the first! lll beam 17 and second
When the rI4 beam 18 reads this, the connection point 21
．． 22, waveforms as shown in FIG. 22 (2) and FIG. 3 (3) are obtained. That is, if there is no flaw 23, waveforms as shown in Figures m4 (2) and (3) are obtained as described above. However, if there is a flaw 23, for example, in the output of the #1 integrated point 21, the output level will suddenly decrease from the displacement Jel due to the flaw 23, and the output level will drop from the displacement i! 1~
The output level during displacement 14 becomes 0, and the output level becomes 0 during displacement 15.
The output level returns to normal. On the other hand, connection point 2
In the case of output No. 2, the output level decreases rapidly from displacement 12, and from displacement 73 to displacement! The output level becomes 0 between degrees 6 and returns to the normal output level at displacement /7. Therefore, the output 11 of the operational amplifier 5 is obtained by subtracting the above two outputs to obtain a waveform as shown in FIG. 4 (4).

The second output 11 is the displacement lO~ affected by the scratch 23
Displacement J! In the section ms1 up to 7, two peaks Pi
, P2 appears. These two peaks P1 and P2 are similar to a plurality of peaks Q 1 , Q 2 , Q 3 , ... (4th flash (4
) and (see FIG. 5 (4)), and such a peak P1. When output 11 including P2 is output as a tracking error signal,
This may cause malfunction of the servo drive means, etc.

On the other hand, the outputs from the wave detectors 9 and 10 are affected by the flaw 23, and waveforms as shown in FIG. 5 (5) and FIG.
A waveform as shown in FIG. 7 (7) is obtained. What should be noted here is the output if, i21! from the operational amplifier 5.6 when a scratch-free disc 12 is read. ,
+ rezo am411m (4) (9) As shown in the figure, the output i1. i2 is lj of the wound
The phase is shifted in the section S1 where the sound appears. That is, the two peaks P3 and P4 appearing in the output 12 affected by the scratches are in opposite phase to the two peaks Pi and P2 described above.

Therefore, the output E from the connection point A is the above two outputs +
1=i2 is added, so the two peaks P 1 ,
P 2 and the peaks P 3 and P 4 cancel each other out, while the two peaks Q1* which are not affected by the scratch 23
Both Qa and Qa are amplified to obtain an output as shown in FIG. 5(8), which is output as a tracking error signal.

In this way, according to the tracking F-signal detection circuit 1 according to the present embodiment and the present invention, when there is no scratch on the disk 12, the output level of the tracking error signal is amplified and the gain of the tracking servo signal becomes high. . Therefore, even if, for example, the disc playback device in which the tracking effect signal detection circuit 1 is used is subjected to vibrations from the outside, the above gain can be set high, so that the main beam 16 will not deviate from the pit row 13. Prevented.

On the other hand, when there is a scratch on the disk 12, the output level of the tracking error signal in the section S1 affected by the scratch is close to 0, so that the 6L deviation of the tracking error signal due to the scratch is minimized. This makes it possible to prevent abnormal situations such as abnormal operation of the optical pickup and rack jumps.

Effects As described above, in the signal reading device according to the present invention,
If there are scratches or the like on the disk body, the level of read output due to the influence of the scratches or the like is reduced, thereby preventing the occurrence of an abnormal situation due to an abnormality in the read output. On the other hand, when reading on a normal disk body, there is no need to take into account the influence of the scratches (it is possible to set the read output gain to a desired level).

[Brief explanation of the drawing]

FIG. 1 is a plot diagram showing the electrical configuration of a tracking F-signal detection circuit 1 which is an embodiment of the present invention, and FIG. 2 is a diagram illustrating the basic operation of the tracking servo mechanism of this embodiment. Figure 4 shows disk 12.
FIG. 5 is a diagram for explaining the operation of the tracking error signal detection circuit 1 when there is no scratch on the disc 12, and FIG. 5 shows the tracking error signal detection circuit 1 when there is a scratch on the disc 12.
FIG. 6 is a block diagram showing the electrical configuration of a typical prior art, and FIG. 7 is a diagram explaining the prior art. DESCRIPTION OF SYMBOLS 1... Tracking error signal detection circuit, 2... Main light detection section, 3... Sub-light detection section, 5, 6... Operational amplifier, 7.8... Amplifier, 9, 10...・Detector, 11
... Sub beam, 12... Disk, 13... Pit row, 16... Main beam, 17... First sub beam,
18...211th Beam Agent Patent Attorney Number of strokes Keiichi 2nd figure Kan 3rd figure

Claims (1)

[Scope of Claims] A disk body in which pit rows are formed along the circumferential direction, and a plurality of circumferential pit rows are formed at intervals in the radial direction, and a pair of detection means for detecting the pit rows. and detecting means for detecting positions on the disk body separated in the radial direction by a distance of half the radial arrangement pitch of the pit rows; a first subtraction means for subtracting the output of the other detection means from the output of the other detection means; a second subtraction means for subtracting the output of the one detection means from the output of the other detection means; and a combination of each detection means and the second subtraction means. A signal reading device characterized by comprising: a phase converting means interposed between the detecting means for converting the phase of the output of the detecting means; and an adding means for adding the respective outputs of the first and second subtracting means.