JPH0524569B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to an optical information reproducing device, and relates to a frame jump for controlling the moving speed of a beam spot irradiated onto an information recording disk during multiple frame jumps. This relates to a speed control method.

[Background of the invention]

Generally, in an optical information reproducing device such as an optical disc player, one frame jump is performed using one jump pulse, and this is repeated to perform special reproduction of still images, triple speed, etc.

FIG. 2 is a waveform diagram for explaining the one frame jump method.

In Fig. 2, a is a jump pulse, b is a kick pulse which is a differential voltage of the jump pulse, and c is a jump pulse.
is a tracking error signal.

The jump pulse shown in FIG. 2a rises at the start of the jump, and falls at the timing when the tracking error signal crosses OV as shown in FIG. 2c. Such a jump pulse is passed through a differentiating circuit to obtain a kick pulse as shown in FIG. 2b, which is amplified and applied to the tracking actuator, thereby driving the tracking actuator.
As a result, the beam spot moves on the disk in the desired direction and jumps to the adjacent track at the rising pulse shown in FIG. 2b. At the same time, keep the trucking loop open. Then, the moving speed of the beam spot is canceled by the next falling pulse,
At the same time, the trucking loop is closed and the servo loop is pulled into the adjacent truck.

By repeating such one-frame jumps, it is possible to perform special playback of still images, triple speed, etc. In this case, the tracking error signal is generated every time one frame jump is performed.
A voltage waveform as shown in FIG. 2c is shown.

The one-frame jump method as described above is disclosed in Japanese Patent Laid-Open No. 128707/1983.

However, in such a one-frame jump method, only one frame jump is performed with one jump pulse, so it is not easy to perform a frame jump of several hundred frames, for example.

Therefore, in order to perform a jump of several frames to several hundred frames using a jump pulse, conventionally, one jump pulse performs an 8 frame jump, and this jump pulse is continuously issued at regular intervals. (n is an integer) frame jump was performed.

However, when an 8-frame jump is performed with one jump pulse, during this jump period, the beam is affected by eccentricity and deceleration by the movable part support of the tracking actuator, so that the beam after the start and before the end of the jump is The spots cross the track at different speeds, resulting in unstable retraction.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a frame jump speed control method that eliminates the drawbacks of the prior art described above and can stably perform a frame jump pull-in operation after multiple frame jumps.

[Summary of the invention]

In order to achieve the above object, the present invention applies a speed control voltage to a tracking actuator to maintain the moving speed of the beam spot at a predetermined speed even at the end of a jump pulse. This is designed to stabilize the retraction of the final frame.

[Embodiments of the invention]

First, the basic principle of the present invention will be explained using the attached FIG. 3.

Figure 3 shows the voltage waveforms of each signal. In the figure, a is the jump pulse, b is the tracking error signal, c is the kick pulse which is the differential voltage of the jump pulse, d is the stiffness cancel cell voltage, and e
is the speed control voltage, and f is the voltage actually applied to the tracking actuator by superimposing c to e.

As is clear from these waveform diagrams, the stiffness cancel voltage (Fig. 3 d), which is a voltage that eliminates the influence of the tracking actuator movable part support, is applied to the tracking actuator, and the jump is applied to the tracking actuator. From an appropriate position from the start (for example, the point at which the tracking error signal between the third frame and the fourth frame becomes O volts (V)), apply the speed control voltage shown in Fig. 3 e for a certain period of time. . That is, by superimposing the speed control voltage on the stiffness cancellation voltage during the jump operation, the movement speed of the actuator is stabilized at the end of a long jump of, for example, 8 frames, and the retraction of the final frame is stabilized. This is what I did.

Next, examples of the present invention will be described. In this embodiment, as a practical matter, the speed control described above is effective only within two frames from the start of the control, so if the stiffness cancel voltage does not correspond to the moving distance of the tracking actuator, An error occurs between 8 frames,
In order to prevent the stability of the pull-in, the period for applying the speed control voltage to the tracking actuator should be set at a predetermined period from 2 to 3 frames before the jump end frame to the end of the jump pulse. This is what I did.

FIG. 1 is a block diagram showing one embodiment of the present invention;
FIG. 4 is a waveform diagram showing the voltage waveforms of the main signals in FIG. 1.

In FIG. 1, 1 is a phase compensation amplifier, 2 is a loop switch, 3 is an adder, 4 is an amplifier, 5 is a tracking actuator, 6 is a speed detection circuit,
7 is a comparator, 8 is an amplifier, 9 is a speed control switch, 10 is a reference voltage generator, 11 is a 6th frame detection circuit, 12 is an 8th frame detection circuit, 13 is a fixed time pulse generation circuit, 14 is a waveform shaper circuit, 1
5 is a counter, 16 is a jump pulse generation circuit,
17 is a differential circuit. 1 and 4, a is a jump pulse, b is a tracking error signal, c is a kick pulse, d is a stiffness cancel voltage, e is a speed control voltage input to the adder 3, and c to e are This is the voltage applied to the actual tracking actuator 5 by applying the voltage.

The operation of this embodiment will be explained.

As shown in FIG. 4, when the tracking error signal b detected by the optical system is input, it is amplified by the phase compensation amplifier 1 and guided to the loop switch 2. When switch 2 is closed, signal b passes through adder 3 and is input to amplifier 4, which drives tracking actuator 5 to control the beam spot to be positioned on the track.

Here, when the jump trigger is input, the jump pulse a rises in the jump pulse generation circuit 16 as shown in FIG. 4a, and at this rise, the loop switch 2 is opened and the tracking servo is turned off.
Further, as shown in FIG. 3, this jump pulse a is differentiated by a differentiating circuit 17 to become a kick pulse c, which is input to an adder 3, amplified by an amplifier 4, and applied to a tracking actuator 5. Therefore, at the rising edge of the jump pulse a, the kick pulse c becomes an upward pulse as shown in FIG. sent to.

On the other hand, at this time, a voltage d that approximately cancels the stiffness of the movable part support of the tracking actuator 5 is applied to the tracking actuator 5 via the adder 3 and the amplifier 4 as shown in FIG. 4d. It is applied gradually.

Now, as the beam spot moves on the disk, the tracking error signal b has a sinusoidal waveform that crosses the OV multiple times as shown in FIG. 4b. At certain numbered points when crossing the OV, the beam spot is located on the track, and at points between the numbers, the beam spot is located between adjacent tracks. Later it is located in the middle of Yodo. Therefore, for example, at time number 3, the beam spot is located on the track of the third frame.

Therefore, the tracking error signal b is inputted to the waveform shaping circuit 14, shaped into a rectangular shape, and then inputted to the counter 15, so that the tracking error signal b is
Count the number of times you cross the OV. Next, the counted result is input to the speed detection circuit 6. The speed detection circuit 6 detects the moving speed of the beam spot by detecting how many times the tracking error signal crosses the OV within a certain period of time, and outputs a voltage corresponding to the moving speed. The output voltage is input to the comparator 7, where it is compared with the reference voltage from the reference voltage generator 10, and the comparison result becomes the speed control voltage and is input to the amplifier 8 and amplified, and then the speed control switch 9 guided by. That is,
The speed control voltage is a voltage that controls the speed in the deceleration direction when the moving speed of the beam spot is faster than the reference speed (speed corresponding to the reference voltage), and in the acceleration direction when it is slower.

On the other hand, the count result from the counter 15 is input to the sixth frame detection circuit 11.
Based on the count result, the sixth frame detection circuit 11 determines the point in time when the tracking error signal b between numbers 5 and 6 shown in FIG. 4b crosses OV (i.e.,
(When the beam spot passes the midpoint between the 5th frame track and the 6th frame track)
When detected, the fixed-time pulse generation circuit 1 closes the speed control switch 9 for a fixed period of time from that point onwards.
Control 3. As a result, the speed control voltage e described above is input to the adder 3, amplified by the amplifier 4, and then applied to the tracking actuator 5. Therefore, while the speed control switch 9 is closed,
The beam spot is controlled so that its cross-track velocity is the same as the velocity immediately after the start of the jump.

Also, the counter result from the counter 15 is 8
It is also input to the frame number detection circuit 12, and its output is input to the jump pulse generation circuit 16. That is, the 8th frame detection circuit 12 uses the count results to select numbers 7 and 8 shown in FIG. 4b.
When the tracking error signal b between As shown in Figure 4a, it is designed to fall. Here, as described above, the jump pulse a is differentiated by the differentiating circuit 17 to become the kick pulse c, which is input to the adder 3, amplified by the amplifier 4, and applied to the tracking actuator 5. Therefore,
At the falling edge of jump pulse a, differentiator circuit 1
The kick pulse c from 7 becomes a downward pulse as shown in FIG. 4c, thereby driving the tracking actuator 5 and causing the loop spot to stop moving. At the same time, the jump pulse generating circuit 16 closes the loop switch 2, so that tracking pull-in is performed thereafter.

Regarding the stability of this tracking pull-in,
As shown in Figure 4c, the impulses of the upward pulse and the downward pulse in the hard pulse c are equal, so
Stable retraction can be achieved by making the cross-track speed of the beam spot immediately before tracking retraction equal to the speed immediately after the start of the jump. Note that the speed can be made equal to the speed immediately after the start of the jump by setting the reference voltage from the reference voltage generator 10 to a desired voltage.

According to the frame jump speed control method of this embodiment, when the stiffness cancelel voltage is larger than the required movement amount of the beam spot, the speed is controlled in the deceleration direction, and when it is smaller, the speed is controlled in the acceleration direction. It is possible to stabilize the retraction at the end of the jump.

〔Effect of the invention〕

According to the frame jump speed control method of the present invention, it is possible to stably perform a frame jump pull-in operation after multiple frame jumps.
Furthermore, by generating jump pulses at regular intervals, frame jumps can be stably performed up to the full dynamic range of the tracking actuator even when the slider that moves the entire information reproducing optical system is stopped. Furthermore, since speed control works effectively during the jump pull-in period,
This has the advantage that the voltage of the stiffness canceler can be easily adjusted.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the present invention;
Fig. 2 is a waveform diagram for explaining the one frame jump method, Fig. 3 is a waveform diagram showing voltage waveforms of main signals in the frame jump speed control method for explaining the principle of the present invention, and Fig. 4 is a waveform diagram for explaining the principle of the present invention. 2 is a waveform diagram showing voltage waveforms of main signals of FIG. 1. FIG. Explanation of symbols, 2... Loop switch, 3... Adder, 5... Tracking actuator, 6...
...Speed detection circuit, 7...Comparator, 8...Amplifier,
9...Speed control switch, 10...Reference voltage generator, 11...6th frame detection circuit, 12...8
Frame detection circuit, 13... Fixed time pulse generation circuit, 14... Waveform shaping circuit, 15... Counter, 16... Jump pulse generation circuit, 17...
Differential circuit, a...Jump pulse, b...Tracking error signal, c...Kick pulse, d...
Stiffness cancellation voltage.

Claims (1)

[Claims] 1. In an optical information reproducing device that obtains a video signal from an information recording disk recorded in a group by irradiating a beam spot, one jump pulse is input to a differentiating circuit and the output voltage drives a tracking actuator. In a frame jump circuit that jumps three or more frames of the video signal by moving the beam spot by moving the beam spot, the beam spot is An optical information reproducing device characterized in that a speed control voltage for maintaining the moving speed at a predetermined speed is applied to the tracking actuator, thereby stabilizing the drawing of the final frame. Frame jump speed control method.