JPH08124333A - Track jumping device in disk reproducing system - Google Patents

Abstract

PURPOSE: To prevent malfunction of stopping a track jump by continuously measuring a pulse width of an output signal under the state of moving a pickup and nulifying a detecting result for a protecting means when a vraibale amt. of a pulse period becomes outside a prescribed range. CONSTITUTION: A tracking error rectangular wave signal at an input terminal 13 is supplied to a counter 1 to measure a pulse period, and is also supplied via a NOT circuit 14 to DFF circuits Q11-Q14. Outputs of the circuits Q11-Q14 are supplied to an AND circuit 15 and a NOR circuit 17, and a deciding result signal in the moving direction of a beam spot is supplied to an OR circuit 19. Thus, when an output signal (i) of the circuit 19 is 'H', it shows that decisions of the circuits 15 and 17 are correct, and when it is 'L', it shows that a deciding result should have an uncertain part. Consequently, correct track jumping operation can be continued by the signal (i) even when noise is mixed in either an envelope component rectangular wave signal of an input terminal 11 or the signal of the terminal 13.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to, for example, a CD / R.
The present invention relates to a disc reproducing system such as an OM (compact disc read only memory) drive, and more particularly to improvement of a track jump device for its high speed search function.

[0002]

2. Description of the Related Art As is well known, in an optical disc reproducing system, a high-speed search function for quickly searching for and reproducing desired data from a huge amount of data recorded on the disc is provided. Equipped. This high-speed search function is aimed at the position where the target data is recorded,
This is realized by moving the optical pickup at high speed in the radial direction of the disc, so-called track jump.

In this case, in the disc reproducing system, the actual beam spot radiated on the disc under the condition that the track jump is executed, that is, the optical pickup is moving at high speed in the radial direction of the disc. The direction of movement is detected.

This is because the optical pickup does not always move in a predetermined direction with respect to the track row due to the influence of the eccentricity of the disk and the external force applied to the optical pickup, and the like. This is to monitor such malfunctions, since it may move in the opposite direction. Then, as a result of detecting the relative movement direction of the beam spot with respect to the track row, when it is determined that the beam spot is moving in the opposite direction to the planned direction, there is a situation that is a hindrance to stably performing the track jump. Since it is happening, I try to stop the track jump immediately.

FIG. 3 is a diagram for explaining a method for detecting the moving direction of the beam spot during a track jump. First, the beam spots are track T1, T2, T3, T4 on the disc as shown by the arrow in FIG.
In the state of traversing in the outer peripheral direction in this order, the optical pickup outputs an RF (high frequency) signal as shown in FIG. 2 (b1), and its envelope component is extracted as shown in FIG. 2 (c1). To be done. Further, in this state, a tracking error signal as shown in FIG. 3 (d1) is obtained.

Then, by slicing the envelope component and the tracking error signal at predetermined positive and negative threshold levels, respectively, an envelope component rectangular wave signal as shown in FIG. 3 (e1) and an envelope component rectangular wave signal as shown in FIG. 3 (f1). Such a tracking error rectangular wave signal is generated, and the moving direction of the beam spot is determined from the relative phase relationship (advance / lag phase relationship) of both rectangular wave signals.

That is, the tracking error rectangular wave signal shown in FIG. 3 (f1) is converted into the first input terminal IN1 shown in FIG.
Via DFF (delay type flip-flop)
It is supplied to the data input terminal D of the circuit Q1 and the envelope component rectangular wave signal shown in FIG. 3 (e1) is supplied to the second input terminal IN2.
Is supplied to the clock input terminal C of the DFF circuit Q1 to latch the tracking error rectangular wave signal shown in (f1) of FIG. 3 (e1) at the rising edge of the envelope component rectangular wave signal shown in (e1) of FIG. From the output terminal OUT of the circuit Q1, an H (high) level detection signal indicating that the beam spot is moving in the positive direction (outer peripheral direction) on the disk is obtained.

On the other hand, the beam spot has tracks T4, T3, T on the disk as shown by the arrows in FIG. 3 (a2).
In the state of traversing in the inner circumferential direction in the order of 2, T1, from the optical pickup, the RF as shown in FIG.
A (high frequency) signal is output and its envelope component is extracted as shown in FIG. Further, in this state, a tracking error signal as shown in FIG. 3 (d2) is obtained.

Then, by slicing the envelope component and the tracking error signal at predetermined positive and negative threshold levels, respectively, an envelope component rectangular wave signal as shown in FIG. 3 (e2) and the same as shown in FIG. 3 (f2). Such a tracking error rectangular wave signal is generated.
Therefore, the DFF circuit Q1 causes the envelope component rectangular wave signal shown in FIG.
By latching the tracking error rectangular wave signal shown in 2), an L (low) level indicating that the beam spot is moving in the negative direction (inner circumferential direction) on the disk from the output terminal OUT of the DFF circuit Q1. Is obtained, and the moving direction of the beam spot is detected.

By the way, in such a beam spot moving direction detecting means, a diagram generated from the tracking error signal at the rise of the envelope component rectangular wave signal shown in FIG. 5A generated from the envelope component of the RF signal. By latching the tracking error rectangular wave signal shown in FIG. 5B, the H level detection signal shown in FIG. When the noise indicated by the diagonal lines is mixed into the tracking error rectangular wave signal shown in FIG. 5B at the time of rising of the envelope component rectangular wave signal shown in FIG. 5B, the beam spot moves in the expected direction. Nevertheless, in the detection signal shown in FIG. 5 (c), a period in the L level state occurs as shown by the diagonal line, and the track jar is correspondingly generated. So that the malfunction stopping the flop will be performed.

That is, in the above-mentioned detecting means, once when the beam spot crosses one track, the determination is made once to determine the level of the other one of the two kinds of rectangular wave signals at the rising time, and the beam is detected. Since the moving direction of the spot is detected, the frequency of discrimination is low and erroneous detection easily occurs.

By the way, as a method for investigating the relative phase relationship (advance / lag relationship) of two types of rectangular wave signals, when the beam spot crosses one track, the rising time point of one rectangular wave signal and Two results obtained by discriminating the level of the other rectangular wave signal at the time of the fall,
A total of four determination results are obtained with the two results obtained by determining the level of one rectangular wave signal at the rising time and the falling time of the other rectangular wave signal, and all the determination results match. It is considered that the result is used as the detection result indicating the moving direction of the beam spot only in the case of performing.

FIG. 6 shows such an improved beam spot moving direction detecting means. That is, the first
The input terminal 11 is supplied with the envelope component rectangular wave signal shown in FIG. 7A generated from the envelope component of the RF signal. The envelope component rectangular wave signal supplied to the first input terminal 11 is the first DFF circuit Q11.
Of the second DFF circuit Q12 and the data input terminal D of the third DFF circuit Q13 via the first NOT circuit 12. It

Further, the second input terminal 13 is supplied with the tracking error rectangular wave signal shown in FIG. 7B generated from the tracking error signal. The tracking error rectangular wave signal supplied to the second input terminal 13 is the data input terminal D and the third D of the first DFF circuit Q11.
The second DFF circuit Q12 is supplied to the clock input terminal C of the FF circuit Q13 and also through the second NOT circuit 14.
Data input terminal D and the clock input terminal C of the fourth DFF circuit Q14. Therefore, each DFF circuit Q1
Output terminals Q of 1, Q12, Q13 and Q14 output latch result signals shown in FIGS. 7C, 7D, 7E and 7F, respectively.

Then, each DFF circuit Q11, Q12, Q
The outputs of 13 and Q14 are supplied to the 4-input AND circuit 15, so that the determination result signal shown in FIG. 7G is obtained from the first output terminal 16. This determination result signal g is H
The level indicates that the beam spot is moving in the positive direction (outer peripheral direction) on the disk, and the level is that the beam spot is moving in the negative direction (inner peripheral direction) on the disk. In addition, each DFF circuit Q11, Q1
The outputs of Q2, Q13, and Q14 are supplied to the 4-input NOR circuit 17 so that the output from the second output terminal 18 shown in FIG.
The determination result signal shown in (h) is obtained. The determination result signal h indicates that the beam spot is moving in the negative direction (inner circumferential direction) on the disk when it is at H level, and the beam spot is positive direction (outer circumferential direction) on the disk when it is at L level. Indicates that you are moving.

The output g of the 4-input AND circuit 15 and 4
The output h of the input NOR circuit 17 and the 2-input OR circuit 19
Is supplied from the third output terminal 20 to FIG.
The corrected determination result signal shown in (i) is output. The corrected determination result signal i indicates that the determination results obtained from the first output terminal 16 and the second output terminal 18 are correct when it is at H level, and the first output terminal 16 and the second output when it is at L level. This indicates that the determination result obtained from the terminal 18 has an uncertain portion.

According to the beam spot moving direction detecting means, the third DFF circuit Q1 can be used when the rectangular wave signal shown in FIG.
The outputs of the third and fourth DFF circuits Q14, the 4-input AND circuit 15 and the 2-input OR circuit 19 are as shown in FIGS.
Even if the shaded portions in (g) and (i) are uncertain, the output signal h of the 4-input NOR circuit 17 has no uncertain portion as shown in FIG. Can be prevented.

However, even by the detecting means as described above, the envelope component rectangular wave signal generated from the envelope component of the RF signal and the tracking error rectangular wave signal generated from the tracking error signal are respectively shown in FIG. ) And (b), if noise is mixed in as indicated by the diagonal lines, each DFF circuit Q11, Q12, Q13, Q
Each output of 14 becomes uncertain at the shaded portions in FIGS. 8 (c), (d), (e), and (f), which results in 4 inputs A
The outputs of the ND circuit 15, the 4-input NOR circuit 17 and the 2-input OR circuit 19 are also uncertain in the shaded portions in FIGS. 8 (g), 8 (h) and 8 (i), which causes a malfunction. .

[0019]

As described above, in the conventional beam spot moving direction detecting means as shown in FIG. 4, it is erroneous that noise is mixed in one of the rectangular wave signals for checking the relative phase relationship. When the detection occurs and the improved moving direction detecting means of the beam spot as shown in FIG. 6 also mixes noise in both rectangular wave signals for examining the relative phase relationship, erroneous detection occurs, and the beam spot becomes There is a problem that a malfunction occurs that stops the track jump even if the track is moved in the correct direction.

Therefore, the present invention has been made in consideration of the above circumstances, and even if noise is mixed in each rectangular wave signal for checking the relative phase relationship and an erroneous detection occurs, a malfunction that stops the track jump may occur. It is an object of the present invention to provide a track jump device of a very useful disc reproducing system which is prevented from occurring.

[0021]

A track jump device of a disc reproducing system according to the present invention comprises a moving means for moving a pickup element for reading data recorded on the disc in a radial direction of the disc, and a pickup element by the moving means. Detecting means for detecting the moving direction of the pickup element on the basis of an output signal obtained from the pickup element in the state where the pickup element is moved in the radial direction of the disc, and the detecting element is different from the moving direction of the pickup element by the moving means. It is intended for a device provided with a protection means for stopping the movement of the pickup element by the movement means when it is determined that the movement is made in the direction. Then, while the pickup element is moving in the radial direction of the disc, a measuring means for continuously measuring the pulse period of the output signal obtained from the pickup element, and the output signal of the output signal based on the measurement result of this measuring means. The control means for invalidating the detection result of the detection means is provided to the protection means when the amount of continuous change in the pulse period is out of the predetermined range.

According to the above structure, the pickup element is moved in the radial direction of the disk at a high speed,
The pulse period of the output signal obtained from the pickup element is continuously measured, and the detection result of the detection unit is invalid for the protection unit when the continuous change amount of the pulse period of the output signal is outside the predetermined range. Therefore, even if noise is mixed in each rectangular wave signal for investigating the relative phase relationship and erroneous detection occurs, it is possible to prevent an erroneous operation of stopping the track jump.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to FIGS. FIG. 1 is a block configuration diagram showing a beam spot moving direction detecting means described in this embodiment, and the same parts as those in FIG. 6 are designated by the same reference numerals. Further, FIG. 2 shows two types of rectangular wave signals for explaining the operation. In FIG. 1, the first input terminal 11 is supplied with the envelope component rectangular wave signal shown in FIG. 2A generated from the envelope component of the RF signal. On the other hand, the second input terminal 1
FIG. 2 shows the waveform generated from the tracking error signal.
The tracking error rectangular wave signal shown in (b) is supplied.

The envelope component rectangular wave signal supplied to the first input terminal 11 is directly or in the first NOT circuit 12 as in the case of the improved configuration shown in FIG.
Is supplied to the data input terminal D or the clock input terminal C of each of the first to fourth DFF circuits Q11 to Q14. That is, this envelope component rectangular wave signal is the first DF
The clock input terminal C of the F circuit Q11 and the fourth DFF circuit Q1
4 is directly supplied to the data input terminal D of the second DFF circuit Q
The clock input terminal 12 of 12 and the data input terminal D of the third DFF circuit Q13 are supplied via the first NOT circuit 12.

The tracking error rectangular wave signal shown in FIG. 2 (b) at the second input terminal 13 is supplied to the counter 21, where the pulse period is measured and at the same time, as shown in FIG.
Similarly to the case of the improved configuration shown in FIG. 3, the data is supplied to the data input terminal D or the clock input terminal C of the first to fourth DFF circuits Q11 to Q14 directly or via the second NOT circuit 14. That is, the tracking error rectangular wave signal is directly supplied to the data input end D of the first DFF circuit Q11 and the clock input end C of the third DFF circuit Q13, and the data input end D of the second DFF circuit Q12 and the fourth DFF circuit Q12.
The clock is input to the clock input terminal C of the DFF circuit Q14 via the second NOT circuit 14.

Therefore, the first to fourth DFF circuits Q1
From the output terminals Q of 1, Q12, Q13, and Q14, respectively, as in the case of the improved example of FIG.
The latch result signals shown in (c), (d), (e), and (f) are output.

The first to fourth DFF circuits Q11,
The outputs of Q12, Q13, and Q14 are supplied to the 4-input AND circuit 15, so that the determination result signal shown in FIG. 7G is obtained from the first output terminal 16. This determination result signal g indicates that the beam spot is moving in the positive direction (outer circumferential direction) on the disk when it is at the H level, and is in the negative direction (inner circumferential direction) when it is at the L level. Indicates that you are moving. Also, the first to the fourth
The outputs of the DFF circuits Q11, Q12, Q13, Q14 are supplied to the 4-input NOR circuit 17, whereby the determination result signal shown in FIG. 7 (h) is obtained from the second output terminal 18. The determination result signal h indicates that the beam spot is moving in the negative direction (inner circumferential direction) on the disk when it is at H level, and the beam spot is positive direction (outer circumferential direction) on the disk when it is at L level. Indicates that you are moving.

The output g of the 4-input AND circuit 15 and 4
The output h of the input NOR circuit 17 and the 2-input OR circuit 19
Is supplied to the output terminal, the corrected determination result signal shown in FIG. 7I is output from the output terminal. When the corrected determination result signal is at the H level, the first output terminal 1
6 shows that the determination results obtained from the second output terminal 18 are respectively correct, and when the L level is the first output terminal 16,
It is shown that the determination result obtained from the second output terminal 18 has an uncertain portion. The first to fourth DFF circuits Q11 to Q14, the first NOT circuit 12, the second NOT circuit 14, the 4-input AND circuit 15, and the 4-input NOR circuit 17 are used.
The above operation obtained by the combination of the two-input OR circuit 19 is the same as the operation in the modified example shown in FIG.

Therefore, the corrected determination result signal i obtained from the 2-input OR circuit 19 is either the envelope component rectangular wave signal at the first input terminal 11 or the tracking error rectangular wave signal at the second input terminal 13. Even if noise is mixed only in the track, the device of this aspect can continue the correct track jump operation without being affected by the noise. However, when noise is mixed in both the envelope component rectangular wave signal and the tracking error rectangular wave signal as shown in FIG. 8, the influence of noise cannot be completely avoided, and for example, a 2-input OR is used. The corrected determination result signal from the circuit 19 still has a problem of uncertainty as shown by the hatched portion in FIG. Here, the output from the 2-input OR circuit 19, that is, the corrected determination result signal is further supplied to the control circuit 24 including the switch 22 and the third NOT circuit 23. The control circuit 24 is controlled by the counter 21 as described later.

Now, returning to FIG. 1, the counter 21
Continuously measures the positive and negative pulse periods of the tracking error rectangular wave signal shown in FIG. The measurement of this pulse feedback is performed by using, for example, a reference clock having a constant cycle as shown in FIG.
The tracking error shown in (b) is realized by counting while resetting at the time of polarity inversion of the rectangular wave signal. These measurement results are further calculated in the counter 21 by calculating the ratio of two consecutive pulse periods, and whether the ratio does not exceed a predetermined value, that is, whether the pulse period does not suddenly change. To be monitored. When a sudden change in the pulse period is observed here, the sudden change information in the pulse period is applied to the control circuit 24.

During the positive and negative pulse periods in which the tracking error rectangular wave signal measured by the counter 21 is sequentially inverted, the noise is not mixed in the signal, and the signal is in accordance with the change of the moving speed of the beam spot in the normal state as shown in FIG. ), It changes like n, n + 1, n + 2, n + 5, .... Therefore, in the normal state, the ratio n / of the pulse periods sequentially obtained before and after the polarity inversion of the tracking error rectangular wave signal is
(N + 1), (n + 1) / (n + 2), (n + 2) /
(N + 5), ... Change in a state of showing a substantially constant value with little fluctuation.

This is the same regardless of whether the moving speed of the beam spot is accelerating or decelerating. Therefore, while the ratio of the pulse periods before and after the polarity inversion of the tracking error rectangular wave signal is changing at a substantially constant value, that is, while the pulse period does not change suddenly, the correction of the output of the 2-input OR circuit 19 is performed. The determined determination result is directly applied from the first switching terminal 22a of the switch 22 to the third output terminal 20. As a result, the output of the 4-input AND circuit 15 or the 4-input NOR circuit 17 is adopted as the detection result that normally indicates the beam spot moving direction.

On the other hand, as indicated by hatching in FIG. 2B, when noise is mixed in the tracking error rectangular wave signal, the positive and negative pulse periods of this tracking error rectangular wave signal are n, n + 1, n + 2, n + 3, n + 4, n + 6. , ... changes like. Therefore, in this case, the ratios n / (n + 1), (n + 1) / (n + 2), (n +) of the pulse periods sequentially obtained before and after the polarity inversion of the tracking error rectangular wave signal are performed.
2) / (n + 3), (n + 3) / (n + 4), (n +
4) / (n + 6), ... Of (n + 2) / (n +
3) shows an extremely high value, while (n + 4) / (n +
It is observed by the counter 21 that 6) shows an extremely low value, and the pulse period suddenly changes in the vicinity of the noise.

As described above, when the ratio of the pulse period before and after the polarity inversion of the rectangular wave signal becomes higher or lower than the predetermined range, it is judged that the sudden change of the pulse period is caused by the noise and the sudden change of the pulse period. Depending on the information, the control circuit 2
The switch 22 in the switch 4 is switched to the second switching terminal 22b, and the corrected determination result, which is the output of the 2-input OR circuit 19, is output from the second switching terminal 22b of the switch 22 to the third NOT circuit 23. It is given to the output terminal 20. As a result, the 4-input AND circuit 15 or 4
Even if an erroneous detection output is generated from the input NOR circuit 17, the erroneous detection output is not adopted and the movement of the beam spot, that is, the track jump can be controlled so as not to be stopped.

In short, the mechanism for moving the optical pickup itself and its objective lens in the radial direction of the disk, that is, the mechanical drive system such as the pickup feed motor and the tracking actuator, is based on a finite electrical input. Since the objective lens and its objective lens are moved, their acceleration and deceleration are also finite, and sudden changes in velocity with extremely large acceleration or deceleration or movement in the opposite direction cannot occur. , It can never happen.

Therefore, when the ratio of the pulse periods before and after the polarity reversal of the rectangular wave signal exceeds the predetermined range and becomes high or low, it can be judged that it is due to the influence of noise, and the detecting means can be used. Even if a detection result indicating that the moving direction of the beam spot is different from the desired direction is obtained, the control circuit 24 is controlled based on the pulse period sudden change information obtained by the counter 21, and the detection result is not adopted. , It is possible to control so that the operation of stopping the track jump is not performed.

In the above description, the reference clock of a constant cycle is counted to measure the positive / negative pulse period of the tracking error rectangular wave signal, but this is, for example, the polarity inversion of the tracking error rectangular wave signal. The pulse period may be measured while resetting at the time point. Also in this case, when the ratio of the pulse periods becomes higher or lower than the predetermined range, it is determined that it is due to the influence of noise, and the detection means detects that the moving direction of the beam spot is different from the desired direction. Even if a result is obtained, it can be judged as an erroneous detection and the track jump can be prevented from being stopped.

The target rectangular wave signal for observing the ratio of the pulse periods may be the envelope component rectangular wave signal shown in FIG. 2A. In this case, the counter 21 has the first input terminal 1
Connected to 1. Further, a similar counter is connected to both the first input terminal 11 and the second input terminal 13 to monitor the sudden change of the pulse period for both the envelope component rectangular wave signal and the tracking error rectangular wave signal. Is most preferred. It should be noted that the present invention is not limited to the above-described embodiments, and can be variously modified and implemented without departing from the scope of the invention.

[0039]

As described above in detail, according to the present invention,
Even if noise is mixed into each rectangular wave signal for investigating the relative phase relationship (advance / lag relationship) and an erroneous detection occurs, an extremely useful disc reproducing system that does not cause the erroneous operation of stopping the track jump. It is possible to provide the track jump device.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a track jump device of a disc reproducing system according to the present invention, showing a beam spot moving direction detecting device.

FIG. 2 is a signal waveform diagram provided for explaining the operation of the apparatus of FIG.

FIG. 3 is a diagram for explaining a method of detecting a moving direction of a beam spot.

FIG. 4 is a block diagram showing a conventional detecting means for realizing a beam spot moving direction detecting method.

FIG. 5 is a signal waveform diagram provided for explaining a problem of the detecting means of FIG.

FIG. 6 is a block diagram showing a detection means improved prior to the present invention for reducing the problems of the detection means of FIG.

FIG. 7 is a signal waveform diagram provided for explaining the operation of the detection means in FIG.

FIG. 8 is a signal waveform diagram provided for explaining a problem of the detecting means of FIG.

[Explanation of symbols]

 11 ... 1st input terminal, 12 ... 1st NOT circuit, 13 ... 2nd input terminal, 14 ... 2nd NOT circuit, 15 ... 4 input AND circuit, 16 ... 1st output terminal, 17 ... 4 input NOR circuit, 18 ... 2 output terminals, 19 ... 2 input OR circuit, 20 ... 3rd output terminal, 21 ... Counter, 22 ... Switch, 23 ... 3NOT circuit, 24 ... Control circuit, Q11-Q14 ... 1st-4th DFF circuit.

Claims (5)

[Claims] 1. A moving means for moving a pickup element for reading data recorded on a disc in a radial direction of the disc, and the pickup element in a state where the pickup element is moved in the radial direction of the disc by the moving means. A detecting means for detecting a moving direction of the pickup element based on an output signal obtained from the element, and a state in which the detecting means determines that the pickup element is moved in a direction different from the moving direction by the moving means. In a track jump device of a disc reproducing system including a protection unit for stopping the movement of the pickup element by the moving unit, in a state where the pickup element is moved in the radial direction of the disc,
Measuring means for continuously measuring the pulse period of the output signal obtained from the pickup element, and a state in which the ratio of the pulse periods before and after the output signal is out of a predetermined range based on the measurement result of the measuring means. The track jump device of the disk reproducing system, further comprising: a control unit that invalidates the detection result of the detection unit with respect to the protection unit. 2. The track jump device of the disk reproducing system according to claim 1, wherein the control means measures the amount of change by the ratio of consecutive pulse periods of the output signal of the pickup element. 3. The measuring means measures a pulse period of an output signal of the pickup element by counting a reference clock having a constant cycle.
Alternatively, the track jump device of the disc reproduction system according to the item 2. 4. The track jump device of the disk reproducing system according to claim 1, wherein the measuring unit measures the pulse period of the output signal of the pickup element by time. 5. The detection means includes a first rectangular wave signal generated from an envelope component of a high frequency signal output from the pickup element when the pickup element is moved in the radial direction of the disc. 2. The disc reproducing apparatus according to claim 1, wherein the moving direction of the pickup element is detected from a relative phase relationship with a second rectangular wave signal obtained from a tracking error signal generated from the output signal of the pickup element. System track jump device.