JP2002237062A - Device for detecting tracking error signal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control, with a simple circuit constitution, deterioration of detecting performance for a tracking error signal caused by an operational speed limit of a circuit and a precision limit of the circuit for detecting the tracking error signal owing to a high density and high linear speeding-up of an optical disk. SOLUTION: Reflected light which is reflected from the information surface of the optical disk is received by a divided light receiving element 601. A phase difference pulse which shows a phase difference between different first and second signals obtained from the divided light receiving element 601 is obtained by a delay element 604a and a phase difference detecting block 609a. At this time, since one side of the first and second signals is delayed by the delay element 604a, the phase difference pulse is provided with an offset in its pulse width and is provided with a margin in its detection width.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tracking error signal detecting device in an apparatus for reproducing information by irradiating a laser beam onto an optical information recording medium such as an optical disk.

[0002]

2. Description of the Related Art In recent years, the density of optical disks has been increasing, but there is a concern that the sensitivity of a tracking error signal may be reduced as the track pitch of an optical disk becomes narrower.

[0003] A conventional tracking error signal detecting device using the DPD method will be described below. FIG. 1 shows a block diagram of a conventional tracking error signal detecting device.

FIG. 1 schematically shows pits 101 and beam spots 102 formed on tracks on the information surface of an optical disk. The beam spot is obtained from a means for irradiating irradiation light with focusing on the information surface. The light reflected from the information surface is guided to the light receiving element 103. The light receiving element 103 is divided into four light receiving elements A, B, C, and D (hereinafter, referred to as four-divided light receiving elements). 104
a and 104b are adders for adding the output signals A1 and C1 and B1 and D1 of the four-divided light receiving elements A to D, respectively.
a, 105b are the outputs S of the adders 104a, 104b.
1, high-frequency emphasis circuits 106a,
Reference numeral 106b denotes a binarizer for converting the outputs of the high frequency emphasizing circuits 105a and 105b into binary signals, 107 a phase difference detector for detecting a phase difference from the outputs S2 and T2 of the binarizers 106a and 106b, and 108a. , 108b are LPFs (low-pass filters) for filtering the two phase difference outputs S3, T4 obtained from the phase difference detector 107, respectively, and 109 is a subtractor for subtracting the outputs of the LPFs 108a, 108b.

The operation of the tracking error signal detecting device will be described below with reference to FIG. FIG. 2 shows each signal S in FIG.
1 schematically shows operation waveforms of 1 to S3 and T1 to T3. Output signal S1 (= (A1 + C1)), which is the sum of the outputs of the diagonal elements among the four divided light receiving elements, T1
(= (B1 + D1)) shows a phase difference depending on the track offset amount when a track offset exists. After boosting the high frequencies of S1 and T1 by the high frequency emphasizing circuit 105, they are converted to binary signals S2 and T2 by the binarizer 106, respectively. Thereafter, the phase difference detector 10
7, the phase difference is detected from the signals of S2 and T2,
If the phase is advanced from T2, it is determined that the phase is advanced, and an advanced phase pulse S3 having a time width corresponding to the phase difference is output. Conversely, if T2 is behind the phase of S2, a delayed phase pulse T3 is output. After passing through an LPF (low-pass filter) 108, S3 and T3 are input to a subtractor 109, where they are subjected to subtraction processing to generate a tracking error signal.

In addition to the above, the output signal (A1 +
In addition to the method of detecting the phase difference of (B1 + D1) in C1), a method of detecting the phase difference between the signals A1 and D1 and the phase difference between the signals C1 and B1 as shown in FIG. is there.

That is, the output signals A1 and D1 are input to the high frequency emphasizing circuits 302a and 302b,
a and 302b are binarized by binarization circuits 303a and 303b, and the phase difference between the binarized signals is detected by a phase difference detector 3
04a. The leading phase pulse and the lagging phase pulse from the phase difference detector 304a are
05b is input to the subtractor 306b. Meanwhile, 4
The output signals B1 and C1 of the divided light receiving elements are output from the high-frequency
2c and 302d and inputted to the high-frequency emphasizing circuits 302c and 302c.
02d is binarized by the binarization circuits 303c and 303d, and the phase difference of the binarized signal is detected by a phase difference detector 304b.
Is detected by The leading phase pulse and the lagging phase pulse from the phase difference detector 304b are LPFs 305c and 305d.
Is input to the subtractor 306b. Subtractor 306
The outputs of a and 306b are added by an adder and used as a phase error signal.

FIG. 4 shows an output signal A of the configuration example shown in FIG.
1 shows a signal processing system on the D1 side. That is, the output of the subtractor 306a may be used as a phase error signal.

By the way, due to the recent increase in the recording density and the increase in the transfer rate of the optical disk, the time width of the phase difference pulse (leading phase pulse, lagging phase pulse) for detecting the tracking error signal has been shortened. It is necessary to detect this with high accuracy. In particular, DVD
In the next-generation high-density optical disk (digital versatile disk), it is expected that the track pitch will be narrower, and it is required that the beam spot follow the track center with high accuracy. In the tracking error signal detection method based on the phase difference detection as in the conventional example represented by the DPD method, when the beam spot is near the track center, the time width of the phase difference pulse to be detected becomes very small. In the next-generation high-density optical disk, there is a problem that the phase difference pulse cannot be detected due to the limit of the operation speed of the detection circuit, and the accuracy of the tracking error signal deteriorates due to the accuracy limit of the pulse width of the detection circuit.

To solve such a problem, Japanese Patent Application No. Hei 8-26
No. 3856 proposes a tracking error signal detecting device capable of detecting a minute pulse width. Japanese Patent Application 8-26
In No. 3856, instead of directly detecting a short pulse width when detecting a pulse width by devising a circuit configuration, two pulses having a pulse width difference corresponding to a phase difference are once generated, and the difference is subtracted by a subtractor. , A minute pulse width is detected by a method independent of the circuit operation speed.

[0011]

However, when the beam spot is scanning near the track center, the phase difference becomes very small, which may exceed the limit of the circuit operation speed of the phase difference detection. Vulnerable to noise,
There is a problem in that the detection sensitivity and the detection accuracy of the tracking error signal are reduced due to the fact that the direction of the phase difference due to the noise is likely to be reversed and the detection circuit is likely to malfunction. In addition, the method described in Japanese Patent No. 2743859 has a problem that the circuit configuration is complicated.

Accordingly, the present invention solves the above-mentioned problems in the conventional tracking error signal detecting device, and can suppress a decrease in the accuracy of tracking error signal detection due to an increase in density and linear velocity, and a tracking error with a simple circuit configuration. It is an object to provide a signal detection device.

[0013]

In order to solve the above-mentioned problems, the basic idea of the tracking error signal detecting device of the present invention is to provide a divided type light receiving device which receives reflected light of a beam applied to an optical disk. The phase of the element and the first and second output signals detected from separate regions of the light receiving element change according to the tracking state of the beam with respect to the optical disk. In the tracking error signal detecting device of the type, the phase of either one of the first and second output signals is delayed so as to have an offset with respect to the phase state detection signal at the time of normal tracking. It was made.

[0014]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 5 is a block diagram of a tracking error signal detecting device according to a first embodiment of the present invention. The optical pickup is a general optical system, and as shown in FIG. 5, the reflected light of the irradiation light applied to the optical disk is incident on a general four-division light receiving element 601 corresponding to the left, right, up, and down of the information track of the optical disk. . The output of the quadrant light receiving element is used to detect a tracking error signal by the procedure described below.

Output signals A1 and B of the quadrant light receiving element 601
Among A1, C1, and D1, A1 and C1 located diagonally are:
The signals B1 and C1 are input to the adder 602a.
2b.

From the adders 602a and 602b, (A1 +
Two direct signals C1) and (B1 + D1) are generated. The direct signal (A1 + C1) is boosted by the high-frequency emphasizing circuit 603a and then branched into two, one of which becomes a delayed signal (A1d + C1d) delayed by the delay element 604a for a fixed time. Similarly, the direct signal (B1
+ D1) is boosted by the high-frequency emphasizing circuit 603b and then branched into two, one of which is a delayed signal (B1d + D1d) delayed for a certain time by the delay element 604b.
Becomes

The delay signal (A1d + C1d) and the direct signal (B1 + D1) are input to a phase difference detection processing block 609a, and the delay signal (B1d + D1d) and the direct signal (A1 + C1) are input to a phase difference detection processing block 609b.
Is input to

In the figure, a phase difference detection processing block 609a is shown.
Are representatively shown. This phase difference detection processing block 6
The operation of detecting the phase difference 09a is as follows.

The delay signal (A1d + C1d) and the direct signal (B1 + D1) are respectively converted to binary signals 605a and 605b.
The signals are converted into binary signals S2 and T2 by the phase difference detector 6
06.

FIGS. 6 and 7 show the configuration of a general phase difference detector and an example of its operation waveform. The phase difference is detected from the signals of S2 and T2, and if the phase of S2 is ahead of T2, It determines that the phase is advanced, and outputs an advanced phase difference pulse S3 having a time width corresponding to the phase difference. Conversely, when T2 is behind the phase of S2, a delayed phase difference pulse T3 is output. That is, the delay signal (A1d + C1d) is directly converted to the signal (B1 +
If the phase is advanced from D1), a leading phase difference pulse S3 is output. Conversely, if the delayed signal (A1d + C1d) is behind the direct signal (B1 + D1), a delayed phase difference pulse T3 is output.

Returning to FIG. The leading phase difference pulse S3 and the lagging phase difference pulse T3 pass through LPFs (low-pass filters) 307a and 307b, respectively, and are subjected to a subtraction process by a subtractor 311 to become a phase difference signal PH1.

Similarly, the direct signal (A1 + C1) and the delayed signal (B1d + D1d) are converted into a phase difference detection processing block 609.
b, and the phase difference processing block 609b outputs a phase difference signal PH2. Then, the phase difference signal P
H1 and the phase difference signal PH2 are subjected to addition processing in an adder 610, and the result becomes a tracking error signal.

Next, the operation of the tracking error signal detecting device according to the present invention will be described. FIG. 8 is a graph of track offset dependency showing detection sensitivity of a tracking error signal obtained by a conventional phase difference detection method. The vertical axis indicates the ratio of the phase difference amount (the sum of the leading phase pulse width and the lagging phase pulse width) detected when the beam spot scans the information track in the tangential direction of the track for a certain distance. When the track offset is 0, the ratio of the phase difference of the detected pulse is 0, and the phase difference of the detected pulse increases as the track offset increases.

There is no problem when the linear density of the optical disk is relatively low and the linear velocity is low. However, as the linear density and the linear velocity increase, the phase difference of the pulse detected with respect to the unit offset amount becomes very small. Therefore, high-precision detection becomes difficult due to the limitation of the operation speed of the pulse width detection circuit and the limitation of the accuracy of the phase difference detection time width.

FIG. 9 is a diagram showing the relationship between the pulse width of the phase difference pulse detected when the beam spot scans the center of the track and the detection frequency. As shown in FIG. 9, when the beam spot scans the center of the track, the frequency of the detected pulse width of the phase difference pulse is most frequently around zero. The small area of the phase difference detection time width which cannot be detected due to the limit of the operation speed of the pulse width detection circuit shown in the shaded area becomes relatively large with respect to the pulse time width distribution as the linear density and the linear velocity increase. Therefore, the detection sensitivity of the actual tracking error signal TE becomes low near the track center as shown in FIG.

In the configuration of the present invention, in the phase difference detection processing, one of the two signals for performing the phase difference detection is subjected to a delay processing for a predetermined time in advance, so that the beam spot scans the center of the track. In this case, the pulse width distribution of the phase difference pulse is centered on the position where the offset for the delay time is added. That is, when the beam spot scans the center of the track, as shown in FIG. 11, in the phase difference detector 606 in the phase difference detection block 609a, the direct signal (B1 + D1) leads the delay signal (A1d + C1d) by a predetermined time. A histogram of the phase difference pulse time width is distributed around the center position, and the track offset dependency of the phase difference detection signal PH1 is as shown by PH1 in FIG.

Conversely, the phase difference detector 606 in the phase difference detection block 609b, as shown in FIG.
1d + D1d) is distributed with a histogram of the phase difference pulse time width centered on a position where the phase difference is delayed by a fixed time from the direct signal (A1 + C1), and the track offset dependency of the phase difference detection signal PH2 is PH2 in FIG. As shown. By averaging the phase difference detection signal PH1 and the phase difference detection signal PH2 shown in FIG. 12A, a tracking error signal is obtained as shown in FIG.

That is, in the configuration of the present invention, even when the beam spot scans near the track center, the time width of the phase difference detection does not become extremely short, and the phase difference detection processing can be performed with high accuracy. It should be noted that the present invention is not limited to the above-described configuration, and that, for example, in either the phase comparator 609a or the phase comparator 609b, the same effect can be obtained even if the input signal is reversed and the adder 610 is changed to a subtractor. Needless to say.

FIG. 13 is a block diagram of a tracking error signal detecting device according to a second embodiment of the present invention.

This embodiment is a method of detecting the phase difference between the signals A1 and D1 and the phase difference between the signals C1 and B1 from the four-division light receiving element and obtaining the average as a tracking error signal.

After the signal A1 from the four-divided light receiving element 1401 is boosted by the high-frequency emphasizing circuit 1402a,
And one of them becomes a delay signal A1d delayed by a predetermined time by the delay element 1403a. Similarly,
After the signal D1 is boosted by the high-frequency emphasis circuit 1402b, it branches into two, one of which is a delay element 1402.
3b becomes a delay signal D1d delayed by a certain time. The phase difference detection processing is performed on the delay signal A1d and the direct signal D1 by the phase difference detection processing block 1404a, and the phase difference signal PH1 is output. Similarly, the phase difference detection processing is performed on the direct signal A and the delay signal D1d in the phase difference detection processing block 1404b, and the phase difference signal PH2 is output.
The phase difference signal PH1 and the phase difference signal PH2 are added to an adder 1409.
a becomes a sum signal, which becomes a phase difference signal PH (A, D) between the signals A1 and D1.

Similarly, the phase difference signal PH3 between the delay signal C1 and the direct signal D1, the phase difference signal PH4 between the direct signal C1 and the delay signal D1 to the phase difference signal PH between the signals C1 and B1.
(C, B) is generated. Next, the phase difference signal PH (A,
D) and the phase difference signal PH (C, B) are averaged to obtain a tracking error signal.

According to the configuration of the present invention, for the same reason as described above, when the beam spot scans near the track center, the phase difference between the signals A1 and D1 and the phase difference between the signals C1 and B1 are almost equal. Since it becomes 0 (the center of the phase difference pulse width distribution is near 0), the detection pulse width at the time of the phase difference detection processing does not become near 0, and a highly accurate phase difference detection processing becomes possible.

Phase difference detection processing blocks 1403a to 1403a
The internal configuration of 03d is the same as that of FIG. 5, and shows the structure of the phase difference detection processing block 1403d as a representative.

In the embodiment of FIG. 11 described above, all of the output signals A1 to D1 of the four-divided light receiving element 1401 are used.
May be used as it is as a phase error signal.

In the present invention, a configuration as shown in FIG. 14 is also possible.

That is, in the embodiment of FIG. 14, the output signals A1 and D1 are input to the high frequency emphasizing circuits 1502a and 1502b. The output of the high-frequency emphasis circuit 1502a is the delay element 1
The signal is input to the phase difference detection processing block 1504a via the signal 503a, and the output of the high frequency emphasis circuit 1502b is directly input to the phase difference detection processing block 1504a.

The output signals B1 and C1 are input to high frequency emphasizing circuits 1502c and 1502d. High frequency emphasis circuit 1
The output of 502d is input to the phase difference detection processing block 1504b via the delay element 1503b,
The output of 502 c is directly sent to the phase difference detection processing block 150.
4b.

A phase difference detection processing block 1504b is shown as a representative. The output of the delay element 1502c and the output of the high-frequency emphasis circuit 1502c are
a and 1505b are binarized. The phase difference between the binary signals is detected by the phase difference detector 1506. The leading phase pulse and the lagging phase pulse from the phase difference detector 1506 are subtracted by the subtractor 1508 via LPFs 1507a and 1507b.
Is input to The output of the subtractor 1508 is
9. The output from the phase error detection processing block 1504a is added and used as a phase error signal.

That is, in this embodiment, when scanning around the center of the track, when detecting the phase difference between the signal A1 and the signal D1, the signal A1 corresponds to a certain time width with respect to the signal D1. The histogram of the detected pulse time width is distributed at the position where the phase of the signal C1 advances, and when the phase difference between the signal C1 and the signal B1 is detected, the phase of the signal C1 corresponding to the fixed time width with respect to the signal B1 is changed. The configuration is such that a histogram of the detection pulse time width is distributed at a position delayed. With such a configuration, it is possible to detect a phase difference with almost the same high accuracy as in the method shown in FIG. 13 and to reduce the circuit scale.

In FIG. 14, it is needless to say that the same effect can be obtained even if the delay processing is performed not on the signals A1 and B1 but on the signals C1 and D1.

FIG. 15 is a block diagram of a tracking error signal detecting device according to a third embodiment of the present invention.

That is, in this embodiment, the detection signal A1
To D1 are high-frequency emphasizing circuits 1603a to 1603d, respectively.
Through the phase difference detection processing blocks 1605a to 1605
5d. The detection signals A1 to D1 are added in an adder 1602, and the added output is input to a delay element 1604 via a high-frequency emphasizing circuit 1603e and is delayed. The output of the delay element 1604 is input to each of the phase difference detection blocks 1605a to 1605d.

Phase difference detection processing blocks 1605a, 16
The output of 05b is input to a subtractor 1610a and subjected to subtraction processing, and the outputs of the phase difference detection processing blocks 1605c and 1605d are input to a subtractor 1610b and subjected to subtraction processing. The outputs of the subtracters 1610a and 1610b are added by an adder 1611. This added output is used as a tracking error signal.

That is, in this embodiment, the signals A1 to D
This is a method in which the phase difference between the sum signal (1) and the sum signal (A1 + B1 + C1 + D1) is independently detected, and the four detected phase difference signals are added or subtracted.

A sum signal (A1 + B1 + C1 + D1) is generated from the signals A, B, C, and D by an adder 1602, boosted by a high-frequency emphasizing circuit 1603e, and then delayed by a delay element 1604 for a predetermined time (A1).
d + B1d + C1d + D1d). High frequency emphasis circuit 1
Signal A boosted by 603a to 1603d
1, B1, C1, and D1 are input to the phase difference detection processing blocks 1605a to 1605d, respectively, and the delayed signals (A1
d + B1d + C1d + D1d), and phase difference signals PH1 to PH4 are output. A subtractor 1610 performs a subtraction process between the phase difference signals PH1 and PH2 and a subtraction process between the phase difference signals PH3 and PH4.
a, 1610b, and the average of the output is the tracking error signal. Signal (A1 + B1 + C1 + D
The offset amount due to the delay processing intentionally given in 1) is
It is just canceled in the subtraction process between the phase difference signals PH1 (PH3) and PH2 (PH4).

Therefore, the tracking error signal becomes 0 when scanning the track center. When the effective pit depth of the optical disk is close to λ / 4n (λ: wavelength, n: refractive index of the substrate), the sum signal (A1 + B1 + C1 + D1) and each signal A1,
Since the phase difference between B1, C1, and D1 approaches 0, a process for performing a delay process on the sum signal (A1 + B1 + C1 + D1) enables a highly accurate phase difference detection process.

In the various embodiments described above, it is desirable that the delay time given in the delay processing be equal to or longer than the minimum detection time width (offset) when the phase difference detection processing of two signals is performed. Also, if the delay time given in the delay processing is too long, the correct phase difference relationship between the two signals cannot be detected, and the detection sensitivity itself deteriorates. Therefore, the delay time reproduces the information signal recorded on the optical disc. It is desirable that the period be equal to or less than the cycle time of the channel frequency used for the control.

[0050]

As described above, according to the structure of the present invention, the operation speed limit of the circuit for detecting the tracking error signal and the tracking error caused by the accuracy limit of the circuit are increased by increasing the density and the linear velocity of the optical disk. Deterioration of the error signal detection performance can be suppressed with a simple circuit configuration.

[Brief description of the drawings]

FIG. 1 is a block diagram of a conventional tracking error signal detection device.

FIG. 2 is a diagram showing an operation example of a conventional tracking error signal detection device.

FIG. 3 is a block diagram of a conventional tracking error signal detection device.

FIG. 4 is a block diagram of a conventional tracking error signal detection device.

FIG. 5 is a block diagram of a first tracking error signal detection device according to the present invention.

FIG. 6 is a configuration diagram of a general phase difference detector.

FIG. 7 is a diagram showing operation waveforms of a general phase difference detector.

FIG. 8 is a diagram showing the track offset dependence of a tracking error signal at low density and low linear velocity.

FIG. 9 is a diagram showing a relationship between a pulse time width of a phase difference pulse detected when a beam spot scans a recording track center and a detection frequency.

FIG. 10 is a view showing the track offset dependence of a tracking error signal at high density and high linear velocity.

FIG. 11 is a diagram illustrating a first tracking error signal detecting device according to the present invention (FIG. 5). When a beam spot scans the center of a recording track, the pulse time width of a phase difference pulse detected by a phase difference detector and detection. The figure which shows the relationship of frequency.

FIG. 12 is a graph of the detected phase difference amounts PH1, PH2 and the track offset dependency of the TE signal when the beam spot scans the center of the recording track in the first tracking error signal detection device (FIG. 5) according to the present invention. FIG.

FIG. 13 is a block diagram of a second tracking error signal detection device according to the present invention.

FIG. 14 is a block diagram of a third tracking error signal detection device according to the present invention.

FIG. 15 is a block diagram of a fourth tracking error signal detection device according to the present invention.

[Explanation of symbols]

101: information pit, 102: beam spot, 60
1, 1401, 1501, 1601... 4-divided light receiving element,
602a, 602b, 610, 1409a, 1409
b, 1410, 1509, 1602, 1611 ... adder, 603a, 603b, 1402a to 1402d, 1
502a to 1502d, 1603a to 1603e... High frequency emphasis circuits, 604a, 604b, 1404a to 1404
d, 1503a, 1503b... delay elements, 304a, 3
04b, 1404a to 1404d, 1504a, 150
4b: phase difference detection block.

Claims (12)

[Claims] A means for irradiating irradiation light while focusing on an information surface of the optical disk during rotation of the optical disk; a plurality of divided light receiving elements for receiving reflected light of the irradiation light; Different first and second signals obtained by using output signals from each element are input to a phase comparison processing means, and a phase difference between the first and second signals is detected to generate a tracking error signal. In the apparatus, any one of the first and second signals is configured to be delayed by a delay element and input to the phase comparison processing means, and a phase difference indicating a tracking error obtained from the phase comparison processing means is provided. A tracking error detection device, wherein a pulse width of a pulse is offset. 2. A means for irradiating irradiation light while focusing on an information surface of the optical disk when the optical disk rotates, a plurality of divided light receiving elements for receiving reflected light of the irradiation light, and a plurality of divided light receiving elements. Means for adding a part of the output signals to generate a first addition signal, and adding a part of the output signals of the divided light receiving elements to generate a first addition signal which is different from the first addition signal. Means for generating an addition signal of 2;
A delay means for delaying the first and second addition signals; detecting a phase difference between the first addition signal and the second addition signal delayed by a predetermined time obtained from the delay means; A first phase difference signal is generated, and a phase difference between the second addition signal and the first addition signal delayed by a predetermined time obtained from the delay means is detected to generate a second phase difference signal. A tracking error signal detection device comprising: a means for setting a difference signal between the first phase difference signal and the second phase difference signal as a tracking error signal. 3. A means for irradiating irradiation light while focusing on an information surface of the optical disk during rotation of the optical disk; a plurality of divided light receiving elements for receiving reflected light of the irradiation light; A delay means for delaying each output signal; an output signal of the first divided area of the divided light receiving element and an output signal of the second divided area of the divided light receiving element obtained by the delay means and delayed by a predetermined time; Means for detecting the phase difference between the divided light receiving element and the output signal of the second divided area of the divided light receiving element and the divided light receiving element delayed by a predetermined time obtained from the delay means. Means for detecting a phase difference with an output signal of the first divided area to generate a second phase difference signal; and using the difference signal between the first phase difference signal and the second phase difference signal as a tracking error signal Output means A tracking error signal detection device, comprising: 4. A means for irradiating irradiation light while focusing on an information surface of the optical disk when the optical disk rotates, a plurality of divided light receiving elements for receiving reflected light of the irradiation light, Calculating means for adding each output signal and outputting an addition signal; and delay means for delaying each output signal of the divided light receiving element and the addition signal, wherein the addition signal delayed by a predetermined time obtained from the delay means To generate a first phase difference signal,
A second phase difference signal is generated by detecting a phase difference between the addition signal and an output signal of the divided region of the divided light receiving element delayed by a predetermined time obtained from the delay means, and the first phase difference signal is generated. A tracking error signal detecting device that uses a difference signal between the first and second phase difference signals as a tracking error signal. 5. The divided light receiving element is a four-divided detector divided into two along a tangential direction of a recording track of the optical disk and further divided into two along a direction orthogonal to a tangential direction of the recording track. Claims 1 to
5. The tracking error signal detection device according to 4. 6. The four-divided detector, wherein the divided light receiving element is divided into two along a tangential direction of a recording track of the optical disc and further divided into two along a direction orthogonal to a tangential direction of the recording track. 3. The tracking error signal detection device according to claim 2, wherein the addition signal is an addition signal of output signals of two divided regions arranged at diagonal positions of the quadrant detector. 7. The divided light receiving element is a quadrant detector divided into two along a tangential direction of a recording track of the optical disc and further divided into two along a direction orthogonal to a tangential direction of the recording track. First of the divided light receiving elements
4. The tracking error signal detecting device according to claim 3, wherein the divided region and the second divided region are arranged at positions facing each other with the tangential direction of the recording track of the four-divided detector as an axis. 8. The divided light receiving element is a quadrant detector divided into two along a tangential direction of a recording track of the optical disc and further divided into two along a direction orthogonal to a tangential direction of the recording track. 5. The tracking error signal detection device according to claim 4, wherein the addition signal is a sum signal of four divided areas of the four-divided detector. 9. A means for irradiating irradiation light while focusing on an information surface of the optical disk during rotation of the optical disk, and dividing the optical disk into two parts along a tangential direction of a recording track of the optical disk for receiving reflected light of the irradiation light. A quadrant detector further divided into two along a direction perpendicular to the tangential direction of the recording track, and a quadrant detector of the four divided regions of the quadrant detector divided into two along a direction perpendicular to the tangential direction of the recording track. Of the tangential front of the recording track
The first divided region and the second divided region,
Assuming that the two divided regions tangentially behind the recording track are a third divided region and a fourth divided region, the phase difference between the output signal of the first divided region and the output signal of the second divided region. For generating a first phase difference signal and detecting a phase difference between the output signal of the third divided area and the output signal of the fourth divided area to generate a second phase difference signal Means for generating a phase difference signal by adding or subtracting the first and second phase difference signals, and means for generating a tracking error signal by smoothing the phase difference signal. A tracking error signal detecting device provided with a fixed phase difference between the output signals of the first and second divided regions and between the output signals of the third and fourth divided regions. And a delay means for applying the irradiation light to the recording track. In the case where the center of the track is scanned in the tangential direction of the track, the output of the third divided area and the fourth divided area between the output signals of the first divided area and the second divided area by the delay means. A tracking error signal detection device, wherein a certain amount of phase difference is generated between signals. 10. A means for irradiating irradiation light by focusing on an information surface of the optical disc when the optical disc rotates, and dividing the optical disc into two parts along a tangential direction of a recording track of the optical disc for receiving reflected light of the irradiation light. A quadrant detector further divided into two along a direction orthogonal to the tangential direction of the recording track, a means for outputting an addition signal obtained by adding output signals of four divided regions of the quadrant detector, Of the four divided areas of the detector, two divided areas tangentially forward of the recording track are divided into a first divided area and a second divided area along the direction orthogonal to the tangential direction of the recording track. Two divided areas tangentially behind the recording track are defined as a third divided area and a fourth divided area, and the added signal and each of the output signals of the first to fourth divided areas are defined as divided areas. And the first to fourth
Means for generating a fifth phase difference signal by subtracting the first phase difference signal and the second phase difference signal, and means for generating a fifth phase difference signal. Means for subtracting the phase difference signal to generate a sixth phase difference signal, means for adding or subtracting the fifth phase difference signal and the sixth phase difference signal to generate a phase difference signal, A tracking error signal detecting device for generating a tracking error signal by smoothing a phase difference signal, wherein a fixed amount is provided between the addition signal and each output signal of the first to fourth divided areas. When the irradiation light scans the track center of the recording track in the tangential direction of the track, the delay signal causes the addition signal and the first to fourth divided areas to be divided by the delay means. A fixed amount of phase difference between each output signal Tracking error signal detecting apparatus characterized by being adapted to generate. 11. The tracking error signal according to claim 1, wherein the shortest time width in which the phase difference can be detected in the phase difference detection is T, and the delay time by the delay means is T or more. Detection device. 12. The delay time by said delay means is T2 or less, where T2 is a cycle time of a channel frequency used for reproducing an information signal recorded on said optical disk. 12. The tracking error signal detection device according to item 11.