JPH05101413A - Optical disk reproducing device - Google Patents

Abstract

(57) [Abstract] [Purpose] To realize a stable track jump in an optical disk reproducing apparatus. [Structure] An acceleration pulse signal and a deceleration pulse signal having opposite polarities are supplied to a tracking coil of an optical pickup 3 to perform a track jump. A detection circuit 24 is provided for detecting the overshoot amount of the tracking error signal when executing the track jump. A circuit for controlling the amount of the acceleration pulse signal or the deceleration pulse signal at the next track jump is provided so that the overshoot amount detected by the detection circuit 24 falls within the specified range.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for stably performing a track jump (jumping the reproduction position of an optical pickup with respect to an optical disk from a certain track to an adjacent track) in an optical disk reproducing apparatus. ..

[0002]

2. Description of the Related Art In an optical disc, various data,
When an information signal such as a video signal or an audio signal is recorded, the information signal is recorded on the disc as one spiral track.

Therefore, as a method of performing a track jump at the time of reproduction, there is a method of supplying a track jump voltage VTJ as shown in FIG. 4A to a tracking coil (tracking actuator) of an optical pickup.

That is, this track jump voltage VTJ
Has a pulse voltage VAT and a pulse voltage VBK that are continuous in opposite polarities. Then, at the time of track jump, the track jump voltage VTJ is supplied to the tracking coil of the optical pickup, the tracking coil is accelerated by the pulse voltage VAT, and the reproduction position of the optical pickup (track position where the reproduction laser beam is scanned) is changed to the current position. Rapid change from track TN to adjacent track TN + 1,
The movement of the tracking coil is braked by the pulse voltage VBK to keep the reproduction position on the track TN + 1.

At this time, if the polarities of the voltages VAT and VBK are reversed, the directions of the track jumps will be reversed.

When the optical disk is a CAV format video disk, still reproduction is performed by repeating a track jump between the track TN and the adjacent track TN + 1 every time the disk makes one revolution. Alternatively, high-speed reproduction can be performed by performing seek by track jump.

[0007]

However, even if the closed-loop tracking servo is applied to the optical pickup, the above-mentioned track jump method is open control, so that the track jump may occur due to variations in the optical pickup or the drive circuit. Becomes unstable, and in the worst case, the track jump may fail.

That is, when the time width and magnitude of the track jump voltage VTJ are appropriate values, the tracking error voltage VER in the tracking servo circuit immediately becomes 0 when the track jump voltage VTJ ends, as shown in FIG. 4B. After convergence, the reproduction position of the optical pickup becomes the correct track position. However, when the braking pulse voltage VBK of the track jump voltage VTJ is insufficient, the tracking error voltage VER overshoots as shown by the solid line in FIG. 4C. Further, when the pulse voltage VBK for braking the track jump voltage VTJ is excessive, as shown by the broken line in FIG. 4C,
The tracking error voltage VER converges slowly.

As indicated by a solid line or a broken line in FIG. 4C, during the period when the tracking error voltage VER has a delay of overshoot or convergence, the reproduction position of the optical pickup is not at the correct track position, so tracking is not performed. It is stable and can result in a failed track jump.

In order to prevent such a trouble, there is also a method of detecting the zero cross of the differential waveform of the tracking error voltage VER and controlling the acceleration and braking of the optical pickup.

However, also in this method, it is difficult to determine the relationship between the time width and the magnitude of the track jump voltage VTJ, and the variation cannot be sufficiently absorbed.

Therefore, conventionally, it is necessary to adjust the time width or magnitude of the pulse voltages VAT and VBK of the track jump voltage VTJ while observing the waveform of the tracking error voltage VER.

The present invention is intended to solve such a problem.

[0014]

When the track jump is performed, the tracking error voltage VER is
As shown in B or C, overshoot occurs, but when a stable track jump is performed, the overshoot amount is small.

Therefore, in the present invention, the magnitude of the overshoot is detected, and the time width or magnitude (voltage value or current value) of the track jump voltage VTJ is controlled so as to reduce it, thereby stabilizing the track jump. It will be transformed.

That is, according to the present invention, when the reference numerals of the respective parts correspond to those of the embodiments described later, the pulse signal VAT for acceleration and the pulse signal VBK for deceleration having mutually opposite polarities.
In an optical disk reproducing apparatus in which the track jump is performed by supplying the signal to the tracking coil of the optical pickup 3, and a detection circuit 24 for detecting the overshoot amount of the tracking error signal VER at the time of executing the track jump, and this detection circuit A circuit 23 for controlling the amount of the pulse signal VAT for acceleration or the pulse signal VBK for deceleration at the next track jump is provided so that the amount of overshoot detected by 24 does not exceed the specified value ± VTH.

[0017]

The function of overshoot of the tracking error signal VER is detected by the first track jump,
According to this detection output, the next and subsequent track jumps are controlled so as to be appropriate and stable track jumps.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1, an optical disc 1 is rotated at a predetermined rotational speed by a spindle motor 2 and an optical pickup 3 is provided so as to face the disc 1, and the optical pickup 3 is fed by a feed motor 4 to the disc 1. Is moved in the radial direction. Then, the pickup 3 reproduces the signal S1 recorded on the disk 1, the reproduction signal S1 supplied to the reproduction circuit 5 decodes or demodulates the original information signal, and the information signal is taken out to the terminal 6. ..

Reference numeral 10 denotes a tracking servo circuit. A reproduction signal S1 from the pickup 3 is supplied to a tracking error detection circuit 11 to extract a tracking error voltage VER. This error voltage VER is switched through a phase compensation circuit 12. It is supplied to the circuit 13. When the switch circuit 13 is in a steady state, that is, when the track jump is not performed, the compensation circuit 12 is provided as shown in the figure.
Is connected to the side. Therefore, in a steady state, the error voltage VER from the compensation circuit 12 is taken out from the switch circuit 13, and the error voltage VER is supplied to the tracking coil (not shown) of the pickup 3 through the drive circuit 14.

Therefore, in the steady state, the tracking servo circuit 10 executes the tracking servo of the optical pickup 3, and the pickup 11 correctly scans the track of the disk 1 to reproduce the signal S1.

Further, the present invention is further configured as follows in order to realize a stable track jump. That is, reference numeral 23 denotes a track jump signal forming circuit, which is constituted by a microcomputer in this example, and the microcomputer also constitutes a system controller for integrally controlling the operation of the entire apparatus. ing. Then, in the forming circuit 23, the track jump voltage VTJ is formed and the control signal S13 of the switch circuit 13 is also formed.

Reference numeral 24 represents an overshoot detection circuit. This detection circuit 24 has a tracking error voltage V
When the overshoot level of ER exceeds the specified value + VTH (or -VTH), the part exceeding the specified value + VTH is output as the detection output V24. The specified value + VTH is the range of the overshoot level at which stable track jump can be performed. In addition, the AND circuit 25 is actually a part of the detection circuit 24, and in this example, the formation circuit 23 is configured by a microcomputer.
Is also formed by a microcomputer forming the forming circuit 23.

Further, at the time of track jump, the tracking error detection circuit 11 outputs the tracking error voltage VER as described above and shown on the left side of FIG. 2C (the same as the solid line of FIG. 4C). The error voltage VER is supplied to the differentiating circuit 21, a differential voltage V21 as shown in FIG. 2D is taken out, and this voltage V21 is supplied to the waveform shaping circuit 22 and binarized, and then the forming circuit 23.
Is supplied to.

At any time t1, for example, when the power is turned on or the optical disk 1 is replaced, the forming circuit 23
At time t2, as shown in FIG. 2B,
A track jump voltage VTJ is formed over time, and this voltage TJ is supplied to the switch circuit 13. Further, in the forming circuit 23, as shown in FIG. 2A, the periods t1 to t2
A control signal S13 that becomes "1" is formed at
Are supplied to the switch circuit 13, and the switch circuit 13 is switched to the forming circuit 23 side in the periods t1 to t2.

Therefore, the track jump voltage VTJ from the forming circuit 23 is supplied to the tracking coil of the optical pickup 3 through the switch circuit 13 and further through the drive circuit 14.

As a result, the track jump of the optical pickup 3 is performed by the track jump voltage VTJ in the period t1 to t2. And at this time, as described above,
Further, as shown in FIG. 2C, the tracking error voltage V
ER changes corresponding to the track jump voltage VTJ. In this case, as shown in FIG. 2C, the tracking error voltage VER may have an overshoot (rather, an overshoot is likely). That is,
Even when the time width or magnitude of the pulse voltages VAT and VBK of the track jump voltage VTJ is not adjusted, an appropriate tracking error voltage VER as shown in FIG.
The time point t2 is set so as to be between the tracking error voltage VER and the overshoot as shown by the solid line.

Then, the tracking error voltage VER having such an overshoot is supplied to the detection circuit 24, and the portion exceeding the specified value + VTH of the error voltage VER is taken out as the detection output V24.

At the tracking error voltage VER due to the track jump in the period t1 to t2 of FIG. 2C, an overshoot of the specified value + VTH or more occurs in the period t3 to t4, so that the period t1 to t2 as shown in FIG. Not only V24 becomes "1" in the middle of, but also the period t3 to t4
Also, V24 = "1". When the direction of the track jump is opposite, the polarities of the track jump voltage VTJ and the tracking error voltage VER are opposite to those in FIGS. Over, at this time, V24 =
It becomes "1".

The output voltage V24 is the AND circuit 2
5 and the signal S13 is supplied to the AND circuit 25, and the AND output V25 which becomes "1" in the period t3 to t4 is taken out from the AND circuit 25 as shown in FIG. 2F. V25 is supplied to the forming circuit 23.

The time width t3 of the output voltage V25
Since t4 corresponds to the magnitude of the overshoot of the tracking error voltage VER (overshoot exceeding the specified value + VTH), the forming circuit 23 corresponds to the time width t3 to t4 of the output voltage V25, and next time. In the following track jumps, the time width of the track jump voltage VTJ, for example, the pulse VBK for braking is widened.

Therefore, when a track jump is next performed during an arbitrary period t5 to t6, as shown in FIG. 2B, the time width of the pulse VBK for braking the track jump voltage VTJ in the period t5 to t6 is equal to the period. t1 ~
Since it is wider than the time width of the braking pulse VBK of the track jump voltage VTJ at t2, the tracking error voltage VER generated by the track jump voltage VTJ during the period t5 to t6 does not cause overshoot as shown in FIG. 2C. Even if it occurs, a small overshoot below the specified value + VTH will occur. Therefore, this period t
The track jump from 5 to t6 becomes a stable track jump, and the track jump does not fail.

All the subsequent track jumps are performed by the same track jump voltage VTJ as the track jumps in the periods t5 to t6, so that the track jumps are stable and the track jumps do not fail.

Thus, according to the present invention, first, the track jump is performed using the appropriate track jump voltage VTJ in the period t1 to t2, and the magnitude of the overshoot of the tracking error voltage VER generated at that time is detected. However, at the next and subsequent track jumps, the time width of the pulse VBK for braking the track jump voltage VTJ is widened according to the detected overshoot magnitude, so that the track is appropriate and stable from the next time onward. You can jump and never fail to jump.

In addition, since the time width or magnitude of the track jump voltage VTJ is automatically set to an appropriate value in this way, the tracking error voltage VER as in the conventional case.
It is not necessary to adjust the track jump voltage VTJ while observing the waveform of.

Further, in the case where the forming circuit 23 is composed of a microcomputer, only a part of the program of the microcomputer needs to be changed and the detection circuit 24 need only be added, which is advantageous in terms of cost. Further, when the optical disc 1 is a writable disc and writing or erasing is performed immediately after the track jump, the overshoot is small, so that the influence on the adjacent track can be reduced.

FIG. 3 shows another example of the present invention, in which the tracking servo circuit 10 is digitized. That is, in this example,
The tracking error voltage VER from the tracking error detection circuit 11 is supplied to the A / D converter 15 and converted into a digital voltage VER, and this digital tracking error voltage VER is supplied to the DSP 16.

According to the program, the DSP 16 outputs the supplied tracking error voltage VER in a steady state, forms the track jump voltage VTJ in a track jump, and tracks the track jump voltage in the first track jump. The overshoot amount of the error voltage VER is detected, and the time width or the magnitude of the track jump voltage VTJ is corrected according to the detection output at the next track jump or later.

The tracking error voltage ER or the track jump voltage VTJ is output from the DSP 16 as a digital voltage, and this voltage VTJ is supplied to the D / A converter 17 and converted into an analog tracking error voltage VER or a track jump voltage VTJ. Was
This voltage VER or VTJ is supplied to the tracking coil of the optical pickup 3 through the drive circuit 14.

Therefore, also in this example, an appropriate and stable track jump is performed, and the track jump never fails.

The abnormal portion (broken line portion) of the tracking error voltage VER that occurs when the braking pulse voltage VBK is excessive as indicated by the broken line in FIG. 4C is also detected by the detection circuit 24.
If it is detected in step 1, the detected voltage V24 and the polarity of the track jump voltage VTJ are used to narrow, for example, the time width of the pulse voltage VBK for braking the track jump voltage VTJ from the next time onward, so that a stable and appropriate track jump can be performed. You can also add actions to take. Then, in this case, the track jump voltage VTJ in the period t1 to t2
The margin can be increased.

[0041]

According to the present invention, first, an appropriate track jump voltage VTJ is used to perform a track jump, and the magnitude of the overshoot of the tracking error voltage VER generated at that time is detected. In the subsequent track jumps, the time width of the track jump voltage VTJ, for example, the pulse VBK for braking is widened in accordance with the detected overshoot, so that an appropriate and stable track jump will be performed from the next time onward. You can do it and you will never fail in a track jump.

Moreover, since the time width or the magnitude of the track jump voltage VTJ is automatically set to an appropriate value in this way, the tracking error voltage VER as in the conventional case.
It is not necessary to adjust the track jump voltage VTJ while observing the waveform of.

Further, in the case where the forming circuit 23 is composed of a microcomputer, only a part of the program of the microcomputer needs to be changed and the detection circuit 24 need only be added, which is advantageous in terms of cost. Further, when the optical disc 1 is a writable disc and writing or erasing is performed immediately after the track jump, the overshoot is small, so that the influence on the adjacent track can be reduced.

[Brief description of drawings]

FIG. 1 is a system diagram showing an example of the present invention.

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

FIG. 3 is a system diagram showing another example of the present invention.

FIG. 4 is a waveform diagram for explaining a conventional example.

[Explanation of symbols]

 1 Optical Disc 2 Spindle Motor 3 Optical Pickup 4 Feed Motor 5 Playback Circuit 10 Tracking Servo Circuit 11 Tracking Error Detection Circuit 14 Drive Circuit 15 A / D Converter 16 DSP 17 D / A Converter 23 Track Jump Signal Forming Circuit 24 Overshoot Detection Circuit VER Tracking error voltage VTJ Track jump voltage

Claims (1)

[Claims] 1. A reproducing apparatus for an optical disc in which a pulse signal for acceleration and a pulse signal for deceleration having mutually opposite polarities are supplied to a tracking coil of an optical pickup to perform a track jump. The detection circuit that detects the overshoot amount of the tracking error signal of and the pulse signal for acceleration or the deceleration signal for deceleration at the next track jump so that the overshoot amount detected by this detection circuit does not exceed the specified value. An optical disk reproducing apparatus having a circuit for controlling the amount of pulse signals.