JPS62125543A - Track jump controller for optical reproducer - Google Patents

Abstract

PURPOSE:To stabilize the working of a deflecting means by detecting the time between the front edge of an acceleration pulse and a zero-cross point near an inflection point of a tracking error signal of a track jump mode and controlling the waveheight value of the acceleration pulse according to said detected time. CONSTITUTION:In a track jump mode the acceleration/deceleration pulse is supplied to a biaxial electromagnetic driver in place of a tracking error signal. Then an objective lens is quickly deflected and the reading beam is shifted by an amount equal to a single tracking so that it crosses the track on an optical disk. An acceleration/deceleration pulse generating circuit 32 produces the acceleration/deceleration pulses. The tracking error signal is supplied to an input terminal 1 and a time detecting circuit 30 detects the time between the front edge of an acceleration pulse and a zero-cross point near an inflection point of the tracking error signal of the track jump mode. A waveheight value control circuit 31 controls the waveheight value of the acceleration pulse by the detection output of the circuit 30. In such a way, the working of a deflecting means can be stabilized in a track jump mode.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a track jump control device for an optical playback device.

[Summary of the invention]

The present invention uses an optical pickup to read recorded information on an optical disk in which information signals are optically recorded so as to form a substantially circular track, and a tracking error detection means detects a scanning deviation of a reading beam with respect to the track. , during a track jump, the deviation means is controlled by the acceleration/deceleration pulse from the acceleration/deceleration pulse generation circuit, and the timing of the transition point between the acceleration/deceleration pulse and the deceleration pulse is determined by the detection output from the tracking error detection means. In a track jump control device for an optical playback device that controls the acceleration/deceleration pulse generation circuit,
A time detection circuit detects the time from the leading edge of the acceleration pulse to a zero cross point near the inflection point of the tracking error signal from the tracking error detection means at the time of track jump, and the detection output of the time detection circuit detects the wave of the acceleration pulse. By providing a peak value control circuit for controlling the peak value, the operation of the deflection means at the time of track jump is stabilized.

[Conventional technology]

In a conventional track jump control device for an optical playback device, an optical big amplifier reads recorded information on an optical disc, in which information signals are optically recorded so as to form a substantially circular track, and a tracking error detection means reads the information recorded on the optical disc. The scanning deviation of the reading beam with respect to the track is detected, and at the time of track jump, the deflection means is controlled by the acceleration/deceleration pulse from the acceleration/deceleration pulse generation circuit, and the acceleration/deceleration pulse is controlled by the detection output from the tracking error detection means. The timing of the transition point between the acceleration pulse and the deceleration pulse is controlled.

[Problem that the invention seeks to solve]

By the way, the above-mentioned acceleration pulse rises when the track jump command signal arrives and falls at the timing of the zero cross point near the inflection point of the tracking error signal from the tracking error detection means, but if the peak value is not appropriate, the Operation becomes unstable. Therefore, in the past, variable resistors were manually adjusted to ensure that the peak value of the acceleration pulse was at an optimal value. However, it is difficult to manually adjust the peak value of the acceleration pulse closely and the adjustment is complicated.

In view of this point, the present invention proposes a track jump control device for an optical playback device that can stabilize the operation of the deflection means during a track jump.

[Means for solving problems]

The present invention deflects a reading beam of an optical pickup for reading recorded information on an optical disk in which information signals are optically recorded so as to form substantially circular tracks in a direction that traverses tracks on the optical disk. a deflection means, a tracking error detection means for detecting a scanning deviation of the reading beam with respect to the track, and an acceleration/deceleration pulse generation circuit that generates an acceleration/deceleration pulse for a track/jump jump and supplies the generated acceleration/deceleration pulse to the deflection means. (32) In a track jump control device for an optical playback device, the timing of the transition point between the acceleration pulse and the deceleration pulse of the acceleration/deceleration pulse is controlled by the detection output from the tracking error detection means, The acceleration/deceleration pulse generation circuit (32) includes a time detection circuit (32) that detects the time from the leading edge of the acceleration pulse to the zero cross point near the inflection point of the tracking error signal from the tracking error detection means at the time of track jump.
30) and a peak value control circuit (31) that controls the peak value of the acceleration pulse based on the detection output of the time detection circuit (30).

[Effect]

According to the present invention, the time detection circuit (30) detects the time from the leading edge of the acceleration pulse to the zero cross point near the inflection point of the tracking error signal from the tracking error detection means at the time of track jump, Based on this detection output, the peak value control circuit (31) controls the peak value of the acceleration pulse to stabilize the operation of the deflection means during track jumps.

〔Example〕

An embodiment of the present invention will be described in detail below with reference to FIGS. 1 and 2. First, an overview of the optical playback device will be explained. Optical discs contain information signals such as
For example, an FM-modulated video signal is recorded to form, for example, a spiral (or concentric) optical recording track (consisting of a row of pits formed on a light reflecting film). Note that it is possible to record not only video signals but also audio signals (digital signals), digital data signals, etc. on the optical disc.

The recorded information on this optical disc is
Play using the tap. This optical pickup focuses a reading beam from a laser light source using an objective lens and irradiates it onto an optical disk.The output light, that is, the reflected beam, is optically detected through an optical system such as an objective lens. The light is made incident on the device, and the reproduced signal of the recorded entertainment is obtained from the photodetector.

The objective lens is also moved by a two-axis electromagnetic drive mechanism (similar to the voice coil of a speaker) as a deflection means.
It is adapted to be deflected in a direction substantially perpendicular to the optical disc and in a direction transverse to its tracks. The deflection of the objective lens is controlled based on the tracking error signal and the focus error signal.

The tracking error signal is used for tracking error detection.
A book beam is irradiated onto an optical disk, and the reflected light is irradiated onto a two-split photodetector via an optical system, and the difference between the rain detection signals is obtained.

The focus error signal is generated by irradiating the reflected beam of the reading beam on the optical disk through a cylindrical lens onto a 4-split photodetector (also used as a photodetector for information signal reproduction). It is obtained from the difference between the sums of detection signals of each pair of photodetectors in the relationship.

During a track jump, instead of a tracking error signal, an acceleration/deceleration pulse is supplied to the two-axis electromagnetic drive to rapidly deflect the objective lens and direct the read beam across the track on the optical disk. I am trying to move it by one track. This track jump
It is used for variable speed reproduction of video signals (still, high speed, low speed, reverse reproduction, etc.) and for accessing a desired track.

When accessing a desired track, this track jump is continuously repeated.

When the reading beam scans a track or jumps a track, depending on the deflection state of the deflection means, the optical pink amplifier itself is moved along the track by a moving means consisting of a motor, rotation-linear motion conversion means, etc. Move it in the cross direction.

Next, with reference to FIG. 1, the main parts of the track jump control device of this optical reproducing apparatus, particularly the acceleration/deceleration pulse generation circuit, will be explained. (32) shows this acceleration/deceleration pulse generation circuit as a whole.

(30) is a time detection circuit that detects the time from the leading edge of the acceleration pulse to the zero cross point near the inflection point of the tracking error signal from the tracking error detection means at the time of track jump. (32) is the time detection circuit (30
) is a peak value control circuit that controls the peak value of the acceleration pulse based on the detection output of the acceleration pulse.

First, the time detection circuit (30) will be explained.

(9) indicates a flip-flop circuit, and a track jump command signal (for example, a positive pulse signal) is supplied from an input terminal (8) to its set input terminal. Incidentally, a detection output of a zero-cross detection circuit (4), which will be described later, is supplied to a reset input terminal of this flip-flop circuit (9). The output of the non-inverting output terminal of the flip-flop circuit (9) is supplied to a monostable multi-bi break (11) serving as a delay circuit with a delay time of A. The output of this monostable multi-bi break (11) is supplied to a monostable multi-bi break (12) serving as a delay circuit with a delay time of B. The outputs of the monostable multi-bibreaks (11) and (12) are supplied to differentiating circuits (16) and (15) via inverters (14) and (13), respectively.

On the other hand, the tracking error signal from the tracking error detection means is sent from the input terminal (1) to the polarity switching circuit (2).
The polarity is switched depending on whether the direction of the track jump is from the inner circumference to the outer circumference on the optical disc or vice versa, and the polarity is switched and the signal is supplied to the zero cross detection circuit (4). be done. Note that (3) is an input terminal for a control signal for polarity switching of the polarity switching circuit (2). The zero cross detection circuit (4) is composed of a comparator (5) and a differentiating circuit (6) at the next stage. The reference level of comparator (5) is the ground level. The output of the zero cross detection circuit (4) is output from the flip-flop circuit (7).
is supplied to the cent input terminal. Note that the differential output obtained by differentiating the output of the flip-flop circuit (9) by a differentiating circuit (10) is supplied to the set input terminal of the flip-flop circuit (7). (17) and (18) are AND circuits. The AND circuit (17) includes the output of the inverting output terminal of the flip-flop circuit (7) and the differential circuit (
15) is supplied. In the AND circuit (18),
The output of the non-inverting output terminal of the flip-flop circuit (7) and the output of the differentiating circuit (16) are supplied.

Next, the peak value control circuit (31) will be explained. (
I9) is an amplifier down counter, the output of the AND circuit (17) is supplied to its up input terminal, and the output of the AND circuit (18) is supplied to its down input terminal. The parallel output of the counter (19) is supplied to the D/A converter (20). The DC output from the D/A converter (20) is supplied to the combiner (23) via an on/off switch (21). This on/off switch (21) is switched and controlled by the output of the flip-flop circuit (9).

(22) is a delay circuit (monostable multi-by-break) as a deceleration pulse generating circuit, and its delay time is C. The monostable multi-high break (22) is supplied with the output of the zero-cross detection circuit (4), and the output thereof is supplied to the synthesizer (23).

The synthesizer (23) synthesizes the acceleration pulse from the on-off switch (21) and the deceleration pulse, which is the inverted output of the output of the monostable multi-high break (22), and has the same configuration as the polarity switching circuit (2). , to the polarity switching circuit (24) which is switched in conjunction with this, and to the output terminal (24).
The acceleration/deceleration pulse obtained in step 6) is supplied to the tracking coil of the above-mentioned two-axis electromagnetic drive mechanism through an amplifier (not shown).

Next, the operation of this embodiment will be explained with reference to FIG. FIG. 2A shows an example of acceleration/deceleration pulses obtained at the output terminal (26). FIG. 2B shows the timing of the deceleration pulse (the time width and peak value are fixed to predetermined values) output from the monostable multi-by-break (22). FIG. 2C shows the timing of the acceleration pulses obtained from the switch (21).

(31), (32), (33) of the second diagram, E and F are,
Three examples of tracking error signals respectively supplied to the input terminal (1) are shown. (41), (42), and (43) are the three outputs of the comparator (5) of the zero-cross detection circuit (4).
The tracking error signal (31),
This corresponds to (32) and (33). Second drawing, M, N (
51), (52), and (53) are zero-cross detection circuits (
4), corresponding to the tiger and king error signals (31), (32), and (33), respectively.

When a track jump command signal (positive pulse signal) is supplied to the input terminal (8), the non-inverting output of the flip-flop circuit (9) rises. This rising point is the rising point t of the timing of the acceleration pulse in FIG. 2C.
corresponds to Thus, the monostable multibibreak (
11) and (12) output pulses a and b shown in FIG. 2 G and H, respectively. The pulse in FIG. 2G rises at a time point and falls after a time A. Also, Figure 2 H
The pulse rises at time B and falls after time B. These pulses a and b are transmitted through an inverter (1
4) and (13) are supplied to differentiating circuits (16) and (step 5) for differentiation, and pulses corresponding to the falling edges of pulses a and b are changed, respectively, to AND circuits (18) and (19).

The tracking error signal supplied to the input terminal (1) is
Depending on the peak value of the acceleration pulse in FIG. 2C, for example, the second
As shown as (31), (32), and (33) in Figs. 2, E, and F, the waveforms are different (therefore, the timing of the zero-crossing point near the inflection point is also different). Compared to other tracking error signals, the tracking error signal (32) in FIG. The acceleration of the deflection means up to this point is constant, indicating that its operation is stable. In order to stabilize the operation of the deflection means during a track jump, it is sufficient that the zero-crossing point near the inflection point of the tracking error signal is within the above-mentioned time B. Therefore, the zero-crossing point near the inflection point of the tracking error signal in FIG. 2E is located within time B. The zero-crossing point near the inflection point of the tracking error signal in Figure 2 is within the above-mentioned time A, and the tracking error signal in Figure 2F (
The zero-crossing point near the inflection point of the tracking error signal in 33) is located at a time that exceeds both times A and B, and both are located at a position outside of time B.

The second
When the pulses (51) and (52) shown in Fig. 2 are supplied, the outputs Ea and Eb shown in Fig. 2 0 and P are obtained from the inverted output terminal, respectively, and are supplied to the AND circuit (18). The inverted output is also supplied to the AND circuit (17).

Therefore, when the time T from the timing rise of the acceleration pulse in FIG. 2C to the zero cross point of the tracking error signal is shorter than the time A (in the case of the tracking error signal (3I) in the second diagram), The signal Ea of O is sent to the AND circuit (18), and its inverted signal is sent to the AND circuit (17).
Since the pulse Pd shown in FIG. 2 is obtained from the AND circuit (18) and is supplied to the down clock input terminal of the counter (19), the counter (19) 1 is subtracted. Also, Figure 2C
The time T from the timing rise of the acceleration pulse to the zero cross point of the tracking error signal is the time A,
When it is between time A+B [in the case of the tracking error signal (32) in Fig. 2 E], the signal Eb in Fig. 2 P is sent to the AND circuit (18), and its inverted signal is sent to the AND circuit (17).
Since no pulse is obtained from either the AND circuit (17) or (18), the coefficient contents of the counter (19) do not change. Furthermore, when the time T from the timing rise of the acceleration pulse in FIG. 2C to the zero cross point of the tracking error signal is longer than the time A+B [second
In the case of the tracking error signal (33) in Figure F], the pulse Pu shown in Figure 2 R is obtained from the AND circuit (17) and is supplied to the up clock input terminal of the counter (19). counter (19) becomes 1.
will be added.

In this way, the acceleration pulse is The wave height value of is controlled to an optimum value to stabilize the operation of the deflection means during the tiger/seven kuji jump. Incidentally, the peak value of the acceleration pulse is inversely proportional to the square of the time T.

Furthermore, the count contents of the counter (19) are calculated by the D/A converter (2).
0) into an analog value that becomes the peak value of the acceleration pulse, and the DC output of that analog value is sent to the switch (21).
is supplied to the synthesizer (23) and is turned on only during the timing period of the acceleration pulse shown in FIG.
An acceleration pulse having a peak value corresponding to the count value of 19) is supplied. Further, the synthesizer (23) is given a deceleration pulse with a constant pulse width and a constant peak value based on the output of the monostable multi-bi break (22), and the synthesizer (23) outputs an acceleration/deceleration pulse resulting from the synthesis of these pulses. The polarity is set by the polarity switching circuit (24), and the output terminal (
26), acceleration/deceleration pulses are output. This acceleration/deceleration pulse is supplied to the tracking coil of the two-axis electromagnetic drive mechanism.

Note that the count value of the counter (19) changes only by 1 for each track jump, so if the initial count value is small, it will take a considerable amount of time for the peak value of the acceleration pulse to reach an appropriate value. Therefore, if the initial count value is set to a standard value in advance, the time required for the peak value of the acceleration pulse to reach an appropriate value can be shortened.

Thus, when an acceleration pulse is applied to the tracking coil during a certain track jump, the above-mentioned time T becomes the reference value (
If the width of B is shorter, the peak value of the acceleration pulse applied to the tracking coil at the next track jump is lowered, and if it is longer, the peak value is increased.

〔Effect of the invention〕

According to the present invention described above, it is possible to obtain a track jump control device for an optical playback device that can absorb variations in the deflection sensitivity during track jumps and stabilize the operation of the deflection means.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is a time chart for explaining its operation. (30) is a time detection circuit, (31) is a peak value control circuit,
(32) is an acceleration/deceleration pulse generation circuit. Figure 2

Claims (1)

[Scope of Claims] A reading beam of an optical pickup for reading recorded information on an optical disc, on which information signals are optically recorded so as to form a substantially circular track, is directed in a direction that traverses the tracks on the optical disc. a deflection means for deflecting the
a tracking error detection means for detecting a scanning deviation of the reading beam with respect to the track; and an acceleration/deceleration pulse generation circuit that generates acceleration/deceleration pulses for track jumping and supplies them to the deflection means; In a track jump control device for an optical playback device, the timing of a transition point between an acceleration pulse and a deceleration pulse of the acceleration/deceleration pulse is controlled by the detection output from the error detection means, and the acceleration/deceleration pulse generation circuit includes: a time detection circuit that detects the time from the leading edge of the acceleration pulse to a zero cross point near the inflection point of the tracking error signal from the tracking error detection means at the time of a track jump; and a detection output of the time detection circuit to detect the acceleration. 1. A track jump control device for an optical playback device, characterized in that it is provided with a peak value control circuit for controlling the peak value of a pulse.