JP2005038524A - Means of pull-in to track of optical information recording and reproducing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To necessitate a cycle detection means with high accuracy at the time of pull-in to track, and to make it possible to perform pull-in to track other than the track having the slope of the targeted tracking error signals. <P>SOLUTION: Pull-in to the track having a slope of always targeted tracking error signals is realized without switching slopes which are used by tracking error signals by slowing down the pull-in to track in an unprescribed certain direction using a voltage according to track direction traveling rate of light which is emitted by a pick-up means, detecting the difference of the cycle of tracking error signals produced thereby, and determining whether it is track having slopes of target tracking error signal. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an optical information recording / reproducing apparatus for the purpose of optically reading information from a recording medium. More specifically, the present invention relates to a track of light emitted by a pickup required for reading information. It is related to retraction.

Conventionally, the track pull-in means of the optical information recording / reproducing apparatus uses a bang-bang generator to determine the slope of the tracking error signal of the track to be pulled that becomes a problem when performing the track pull-in using the tracking error signal. Accelerates / decelerates the light emitted by the pickup onto the disk surface in any track direction, detects the difference in the period of the tracking error signal generated thereby, determines the pull-in direction, and the tracking error signal according to the track to be pulled in The track pull-in is performed by switching the slope (see, for example, Patent Document 1).
Japanese Patent Laid-Open No. 10-172514

  In such a track pull-in means of the optical information recording / reproducing apparatus, the bang-bang is used to determine the slope of the tracking error signal of the track drawn from the direction of movement of the light irradiated onto the disk surface when the track is drawn. High-accuracy period detection that can detect the difference in the tracking error signal period by detecting the difference in the period of the tracking error signal by accelerating and decelerating the light emitted from the pickup onto the disk surface by the generator. Means are needed. Further, since the slope of the tracking error signal is switched in accordance with the track to be pulled in, it is not always possible to pull in the track having the target tracking error signal slope.

  In view of the above problems, the present invention generates a voltage corresponding to the moving speed in the track direction of the light irradiated by the pickup means at the time of track pull-in, and uses the difference in the period generated thereby to target the tracking error signal. Track of an optical information recording / reproducing apparatus that can determine whether the track has a slope of a predetermined error and can be pulled into a track having a slope of the target tracking error signal without switching the slope of the tracking error signal It was made for the purpose of providing a retracting means.

  In order to solve this problem, the track pull-in means of the optical information recording / reproducing apparatus of the present invention comprises: pickup means for reading a signal recorded on a track by causing the light irradiated on the disk surface to follow the track; Tracking error signal detecting means for detecting an error in the track direction from a signal generated by the pickup means and outputting a tracking error signal; Period detecting means for detecting the period of the tracking error signal output by the tracking error signal detecting means; A tracking error which is a target based on a difference in the period of the tracking error signal detected by the period detecting means, and a speed detecting means for detecting the moving speed of the light emitted from the pickup means in the track direction from the period of the period detecting means; Has signal slope Track detecting means for detecting a track to be detected, track pull-in control voltage generating means for generating a voltage corresponding to the speed detected by the speed detecting means and arbitrarily controlling the voltage generation timing, and the track pull-in control Tracking drive means for moving the light emitted from the pickup means in the track direction by the voltage output from the voltage generating means is provided.

  Thus, the track has a slope of the target tracking error signal by generating a voltage corresponding to the moving speed in the track direction of the light irradiated by the pickup means at the time of pulling the track, and using the difference in the period caused thereby. Thus, it is possible to obtain the effect of enabling the drawing to the track having the target tracking error signal slope without switching the tracking error signal slope.

  As described above, according to the present invention, a voltage corresponding to the speed at the start of track pull-in is applied, and a track having a target tracking error signal slope is compared by comparing the difference in the period of the tracking error signal before and after that. An advantageous effect is obtained that it is possible to detect and promptly pull into a track having a target tracking error signal slope.

  According to a first aspect of the present invention, there is provided pickup means for reading a signal recorded on a track by causing light irradiated onto a disk surface to follow the track, and an error in a track direction from the signal generated by the pickup means. And a tracking error signal detecting means for detecting a tracking error signal, a period detecting means for detecting a period of the tracking error signal output by the tracking error signal detecting means, and a first pick-up means from the period of the period detecting means Track detection for detecting a track having a slope of a target tracking error signal based on a difference in the period of the tracking error signal detected by the period detection unit; Means and said speed A track pull-in control voltage generating means for generating a voltage corresponding to the speed detected by the output means and arbitrarily controlling the voltage generation timing; and the pickup means based on the voltage output from the track pull-in control voltage generating means Tracking drive means for moving the light radiated in the track direction, and generating a voltage according to the moving speed in the track direction of the light radiated by the pick-up means at the time of track pull-in By using the difference, it is possible to determine whether the track has the target tracking error signal slope, and it is possible to pull in the track having the target tracking error signal slope without switching the tracking error signal slope. Tokusaku Having.

  According to a second aspect of the present invention, the light picked up by the pickup means from the voltage of the tracking error signal output by the tracking error detection means after an arbitrary time has passed after passing through the center of the track where the pull-in is started. And a speed detecting means for detecting the moving speed in the track direction, and has an effect that more stable track pull-in can be performed by detecting the speed more accurately.

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

(Embodiment 1)
FIG. 1 shows the structure of the track pull-in means of the optical information recording / reproducing apparatus in the first embodiment of the present invention. In FIG. 1, 1 is a disk on which a signal is recorded, 2 is an arbitrary disk 1 3 is a pick-up means for reading the signal recorded on the track by causing the light irradiated on the surface of the disk 1 to follow the track, and 4 is an error in the track direction from the signal generated by the pick-up means 3. Tracking error signal detecting means 5 for detecting and outputting a tracking error signal 5 is a comparator for binarizing the tracking error signal output from the tracking error signal detecting means 4, and 6 is a tracking binarized by the comparator 5. Cycle detection means for detecting the cycle of the error signal, 7 is a cycle of the cycle detection means 6 8 is a speed detecting means for detecting the moving speed of the light emitted from the pickup means 3 in the track direction, and 8 is a track having a target tracking error signal slope based on the difference in the period of the tracking error signal detected by the period detecting means 6. 10 is a track pull-in control voltage generating means for generating a voltage corresponding to the speed detected by the speed detecting means 7 and arbitrarily controlling the voltage generation timing. 10 is a track pull-in control voltage. It comprises tracking drive means for moving the light emitted from the pickup means 3 in the track direction by the voltage output from the generating means 9.

  The operation of the track pulling means of the optical information recording / reproducing apparatus configured as described above will be described below.

First, FIG. 2A shows a trajectory in which light emitted from the pickup means 3 moves on a track on the surface of the disk 1 when the track is drawn. In the state where the track is not drawn, the light irradiated by the pickup means 3 moves in the track direction due to the eccentricity of the disk 1 and the disk 1 is rotated by the motor 2 so The light will cross the track diagonally. Here, a track having a target tracking error signal slope is indicated by hatching, and the tracking error signal slope is negative on the outer peripheral side and positive on the inner peripheral side, and is directed from the outer peripheral side to the inner peripheral side. When the light is moving, the tracking error signal output from the tracking error detection means 4 is as shown in FIG. 2B, and the waveform obtained by binarizing the signal by the comparator 5 is as shown in FIG. Become. If the track pull-in operation is set to be performed at the rising edge of the binarized waveform of the comparator 5 in this state, first, the rising edge of an arbitrary binarized waveform to be pulled in and the rising edge of the previous binarized waveform. The period detection means 6 measures the time interval from the falling edge. Assuming that the time measured here is t0, the speed detection means 7 is a track having a tracking error signal slope on the disk 1 as the moving speed v0 in the track direction when light passes through the track center where the track pull-in has started. For the distance L between
v0 = (L / 2) / t0
And approximate. In accordance with this speed v0, the track pull-in control voltage generating means 9 generates an output voltage having an arbitrary polarity. Here, assuming that the conversion coefficient of the voltage generated with respect to v0 is k and the polarity of the generated voltage is positive, the voltage generated by the track pull-in control voltage generating means 9 is
V0 = k × v0
The waveform is shown in FIG.

The voltage V0 generated by the track pull-in control voltage generation means 9 is input to the tracking drive means 10 and moves the light irradiated by the pickup means 3 in the track direction. In this state, the moving speed v and the moving distance x of the light in the track direction are expressed as α for the acceleration with respect to the drive voltage of the pickup means 3, and the tracking drive means 10 outputs the input voltage for driving the pickup means 3. Assuming that the coefficient to be converted into a voltage to be m is t, and the elapsed time from the generation of the voltage V0 from the track pull-in control voltage generating means 9 at the pull-in start point is t.
v = v0− (α × (m × V0) × t)
x = (v0 × t) − ((1/2) × α × (m × V0) × (t ^ 2)
It becomes. Here, when the direction of movement of the light irradiated by the pickup means 3 when the output voltage of the track pull-in control voltage generation means 9 is positive is the outer peripheral side, the light traveling on the track decelerates in the track direction, It reverses when the velocity v = 0, moves this time while accelerating toward the outer periphery, and passes through the center of the track where the pull-in is started again. At this time, the binarized waveform passes in the reverse direction through the track having the same tracking error signal slope as that of the track from which the track pull-in is started, so that a falling edge occurs. The period t6 measures the time t1 from the start of the track pull-in until the first falling edge occurs, and the track detector 8 sets the time interval t0 between the edges of the binarized waveform before the track pull-in starts. In comparison, when t0 <t1, it is determined that the track that has been pulled in is a track having a target tracking error signal slope, and is pulled into the track.

When the track pull-in control voltage generation means 9 determines that the track started by the track detection means 8 has a target tracking error signal slope, the track pull-in control voltage generation means 9 decelerates the light moving in the outer peripheral direction, In order to return to the center, a voltage V1 corresponding to the track center passing speed v1 is output, and after an arbitrary time t2 set according to the track center passing speed v1, a track of a track having a target tracking error signal slope In order to reduce the moving speed of light in the track direction at the center, the inverted output V2 is output for an arbitrary time t3 set according to the track center passing speed v1. When these relationships are expressed by equations, V0 = −V1, t2 is switched to the inverted output V2 when the position reaches a quarter of the distance between the tracks having the target tracking error signal slope with respect to the track center. Then,
v1 = v0
(L / 4) = (v1 × t2) − ((1/2) × α × (m × V0) × (t2 ^ 2))
v2 = v0− (α × (m × V0) × t2)
v2 = α × (m × V2) × t3
(L / 4) = (1/2) × α × (m × V2) × (t3 ^ 2)
It becomes.

  By satisfying the above conditions in this way, if the track that started track pull-in is a track having a target tracking error signal slope, the track can be pulled into the track.

  Next, a case where the track from which the track pull-in starts is not a track having a target tracking error signal slope will be described.

First, FIG. 3- (a) shows the trajectory along which the light irradiated from the pickup means 3 moves on the track on the surface of the disk 1 when the track is drawn, as in FIG. 2- (a). However, here, unlike the case of FIG. 2A, it is assumed that the light is moving from the inner circumference side of the disk toward the outer circumference side. The tracking error signal output from the tracking error detection means 4 is shown in FIG. 3- (b), and the waveform obtained by binarizing the tracking error signal by the comparator 5 is shown in FIG. 3- (c). In this state, the track pull-in operation is performed at the rising edge of the binarized waveform of the comparator 5 as in the case where the light has moved from the outer peripheral side to the inner peripheral side. The period detection means 6 measures the period of the rising edge of the binarized waveform to be drawn in and the previous falling edge, and the track pull-in control voltage generation means 9 is in accordance with the speed approximated by the speed detection means 7. Generate voltage. The generated voltage is the same as when the light is moving from the outer periphery to the inner periphery.
V0 = k × v0
Thus, the waveform is as shown in FIG. However, unlike the case where the light has moved from the outer peripheral side to the inner peripheral side, the tracking error signal waveform is inverted with respect to the track having the same tracking error slope because the direction passing through the track is different. The direction of the edge of the value waveform is also reversed. Therefore, when the track pull-in is started at the rising edge, the track is not a track having a target tracking error signal slope, and the voltage output from the track pull-in control voltage generating means 9 is a light beam that moves to the inner circumference side. Since it is output to the polarity which decelerates, when light has moved to the outer peripheral side, it will accelerate toward the outer peripheral side. The speed v and the distance x in the track direction of the light moving along the track at this time are
v = (v0) + (α × (m × V0) × t)
x = (v0 × t) + ((1/2) × α × (m × V0) × (t ^ 2))
Thus, a track having a target tracking error signal slope on the outer peripheral side of the track that has started to be pulled in is passed. At this time, since the tracking error signal slope is reversed with respect to the track that started track pull-in, the track passing through is binarized by passing the track from the inner circumference side to the outer circumference side in the same direction. The waveform generates a falling edge. The time t1 from the start of the track pull-in to the first falling edge is measured by the cycle detection means 6, and when the track detection means 8 is compared with the cycle t0 before the track pull-in start, t0> t1, and the pull-in is performed. It is detected that the track that has passed has not the target tracking error signal slope, but the next track that has the target tracking error signal slope, and the track is pulled into the track.

The track pull-in control voltage generating means 9 judges that the track has a slope of the tracking error signal targeted at the track where the trailing edge of the binarized waveform next to the track where the track detecting means 8 has started track pull-in has occurred. Then, the light traveling in the outer peripheral direction is decelerated, and a voltage V1 set according to the track center passing speed v1 is output in order to pull back to the track center of the track having the target tracking error signal slope, After a time t2 set according to the track center passing speed v1, elapses, a time t3 when the inverted output V2 is set according to the track center passing speed v1 in order to make the moving speed of light in the track direction zero on the track center. Output during. When these relationships are expressed by equations, when V0 = −V1, t2 is set to a point that has reached a position that is ¼ of the distance L between tracks with respect to the track center, switching to the inverted output V2 is performed.
v1 = (α × (m × V0) × t) + v0
v1 = α × (m × V0) × t21
v2 = (v1) + (α × (m × V0) × t2)
(L / 4) = (v1 × t2) − ((1/2) × α × (m × V0) × (t2 ^ 2))
v2 = α × (m × V2) × t3
(L / 4) = (1/2) × α × (m × V2) × (t3 ^ 2)
It becomes.

  In this way, by satisfying these conditions, if the track that started track pull-in is not a track having the target tracking error signal slope, the target tracking error signal adjacent to the track It can be pulled into a track with a slope.

However, as shown in this example, in order to determine whether or not the track to start pulling is a track having a target tracking error signal slope, the light moves from the outer peripheral side to the inner peripheral side. In such a case, after passing the track, when passing through an adjacent track center, an edge of a binarized waveform is generated. Correct track detection will not be possible. Therefore,
(L / 2)> ((v0 × t) − (1/2) × α × (m × V0) × (t ^ 2))
The conversion coefficient k that is arbitrarily set by the tracking pull-in control voltage means 9 must be set so that the voltage V0 that satisfies the above condition is generated.

In addition, when the track that has started pulling is a track having a target tracking error signal slope, in order to detect this, time t1 from the start of track pulling to the edge of the next binarized waveform Is larger than the time t0 before the start of track pull-in,
t0 <(2 × v0 / (α × (m × V0))
The conversion coefficient k that is arbitrarily set by the tracking pull-in control voltage generating means 9 must be set so that the voltage V0 that satisfies the above condition is generated.

  As described above, according to the present embodiment, the target tracking error signal is obtained by comparing the period of the edge of the binarized waveform before the start of track pull-in with the period of the edge of the binarized waveform after the start of track pull-in. It is possible to detect a track having a certain slope and draw it into the track.

  In the example of the first embodiment, the tracking pull-in control voltage generating means 9 generates a constant voltage during the interval from the edge of the binarized waveform where the track pull-in has started to the edge of the binarized waveform to be generated next. However, the track pull-in control voltage generation means 9 may generate a voltage for an arbitrary fixed time from the edge of the binarized waveform at which the track pull-in is started or an arbitrary time corresponding to t0. The voltage to be used may not necessarily be a constant voltage, but may be a voltage corresponding to a tracking error detected by the tracking error detection means 4 or a change in voltage.

  In this example, if the track pull-in start track is not a track having a target tracking error signal slope, the track pull-in start track is designed to be pulled into an adjacent target track error signal slope. If the track does not have a target tracking error signal slope, the pull-in operation may be stopped and the track pull-in operation may be performed again.

(Embodiment 2)
FIG. 4 shows the track pull-in means of the optical information recording / reproducing apparatus according to the second embodiment. 4, reference numerals 1 to 6 and 8 to 10 are the same constituent elements as those in the first embodiment shown in FIG. 1 and are denoted by the same reference numerals. Reference numeral 7 denotes an arbitrary lapse of time after passing through the center of the track where the pull-in starts. The speed detection means detects the moving speed of the light irradiated by the pickup means 3 in the track direction from the voltage of the tracking error signal output by the tracking error detection means 4 after the above.

  The operation of the track pulling means of the optical information recording / reproducing apparatus configured as described above will be described below.

  First, as in the first embodiment, when the track pull-in is started at an arbitrary edge of the binarized waveform of the comparator 5, the speed in the track direction when passing the track center is detected, and the track pull-in control is performed according to the detected voltage. In the case of the first embodiment, the time interval between the edge at which the track pull-in is started and the edge generated immediately before is measured by the period detecting means 6, and the distance between the tracks is generated. The average speed between them was calculated and approximated as the speed in the direction of the track passing through the center of the pull-in start track. An error occurs between them. In Embodiment 1, since the measured time interval is converted into a voltage, a conversion circuit for that purpose is required.

  In order to solve this problem, the speed detection circuit 7 of FIG. 4 is shown in FIG. 5- (b) after an arbitrary time Δt has passed since passing through the center of the pull-in start track as shown in FIG. 5- (a). The tracking error voltage is measured and multiplied by a coefficient, and the track pull-in control voltage generating means 9 generates a voltage.

The speed v0 in the track direction when passing through the center of the track drawing start track is x, where x is the distance from the track center to the position of the irradiated light.
v0 = x / Δt
Assuming that the coefficient of the distance of the position of the light irradiated from the track center and the tracking error signal voltage generated with respect to the distance is A, the tracking error signal voltage TE at that time is
TE = A × x
The voltage V0 generated by the track pull-in control voltage generation means 9 is expressed as follows, assuming that the conversion coefficient for the voltage input from the speed detection means 7 is K.
V0 = K × TE
It becomes. Hereinafter, track detection and pull-in are performed in the same manner as in the first embodiment.

  As described above, according to this embodiment, by using the voltage of the tracking error signal after an arbitrary fixed time at the start of track pull-in, more accurate speed detection can be performed and more stable track pull-in can be realized. Will be able to.

1 is a block diagram of a track pull-in means of an optical information recording / reproducing apparatus according to an embodiment of the present invention. FIG. 4 is a waveform diagram of light and a track of each part irradiated on a track on a disk surface when track pull-in is started on a target slope track according to an embodiment of the present invention. FIG. 7 is a waveform diagram of light and a locus of light applied to a track on a disk surface when track pull-in is started on a track that is not a target slope according to an embodiment of the present invention. 1 is a block diagram of a track pull-in means of an optical information recording / reproducing apparatus according to an embodiment of the present invention. FIG. 6 is a waveform diagram of light and a tracking error signal waveform applied to a track on a disk surface immediately after starting track pull-in according to an embodiment of the present invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Disc 2 Motor 3 Pickup means 4 Tracking error detection means 5 Comparator 6 Period detection means 7 Speed detection means 8 Track detection means 9 Track pull-in control voltage generation means 10 Tracking drive means

Claims (2)

In an optical information recording / reproducing apparatus using a signal recorded on a concentric circular or spiral track on a disk, pickup means for reading the signal recorded on the track by causing the light irradiated on the disk surface to follow the track A tracking error signal detecting means for detecting a tracking direction error from a signal generated by the pickup means and outputting a tracking error signal; and a period for detecting a period of the tracking error signal output by the tracking error signal detecting means A detection means; a speed detection means for detecting a moving speed of light in the track direction irradiated by the first pick-up means from a period of the period detection means; and a target based on a difference in the period of the tracking error signal detected by the period detection means. Tracking error Track detection means for detecting a track having a slope of a signal, track pull-in control voltage generation means for generating a voltage according to the speed detected by the speed detection means, and arbitrarily controlling the voltage generation timing; Track pulling means for an optical information recording / reproducing apparatus, comprising: tracking drive means for moving light emitted from the pickup means in the track direction by a voltage output from the track pull-in control voltage generating means. 2. The optical information recording / reproducing apparatus according to claim 1, wherein the first pick-up is performed from the voltage of the tracking error signal output by the tracking error detecting means after an arbitrary time has passed after passing through the center of the track to start pulling. 2. The track pull-in means of the optical information recording / reproducing apparatus according to claim 1, further comprising speed detecting means for detecting the moving speed of the light irradiated by the means in the track direction.

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