JPS62128026A - Track jump controller for optical reproducing device - Google Patents

Abstract

PURPOSE:To stabilize quickly the operation of a deflecting means for track jump by providing an acceleration/deceleration pulse generating circuit with a time detecting means, which detects the time to a zero-crossing point near an inflection of a tracking error signal, and a crest value operating means which calculates an optimum crest value of an acceleration pulse. CONSTITUTION:An acceleration/deceleration pulse generating circuit 12 is provided with a time detecting means 3a, which detects the time from the leading edge of the acceleration pulse to the zero-crossing point near the inflection point of the tracking error signal from a tracking error detecting means for track jump, and a crest value operating means 3b which calculates an optimum crest value of the acceleration pulse on a basis of the detection output of the time detecting means 3a. The time from the leading edge of the acceleration pulse to the zero-crossing point near the inflection point of the tracking error signal from the tracking error detecting means for track jump is detected by the time detecting means 3a, and the optimum crest value of the acceleration pulse is calculated on a basis of the detection output by the crest value operating means 3b. Thus, the operation of the deflecting means for track jump is stabilized quickly.

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 the trunk jump control device of the optical playback device, which controls the acceleration/deceleration pulse generation circuit,
A time detection means detects the time from the leading edge of the acceleration pulse to a zero cross point near the inflection point of the trunking error signal from the tracking error detection means at the time of track jump, and acceleration is performed based on the detection output of the time detection means. By providing a peak value calculation means for calculating the optimum pulse height value of the pulse, the operation of the deflection means at the time of a track jump can be quickly stabilized.

[Conventional technology]

In a conventional trunk jump control device for an optical playback device, an optical pick 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 trunk 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 strictly manually adjust the peak value of the acceleration pulse, and the adjustment is complicated.

In view of this, the present invention proposes a track jump control device for an optical playback device that can quickly stabilize the operation of the deflection means during a trunk 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 trunk, and an acceleration/deceleration pulse generation circuit (12) that generates acceleration/deceleration pulses for track jump 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 an acceleration/deceleration pulse is controlled by a detection output from a tracking error detection means. In (12), time detection means (3a
) and peak value calculation means (3b) for calculating the optimum peak value of the acceleration pulse based on the detection output of the time detection means (3a).
It is characterized by having the following.

[Effect]

According to the present invention, the time detection means (3a) 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 optimal peak value of the acceleration pulse is calculated by the peak value calculating means (3b), thereby quickly stabilizing the operation of the deflecting means at the time of track jump.

〔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 pinodos 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 reproduced using an optical P7. 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. A reproduction signal of the recorded information 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 trunk on the optical disk. I'm trying to move it by a track. This track jump is used for variable speed playback (still, high speed, low speed, reverse playback, etc.) of a video signal and for accessing a desired track.

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

When the reading beam scans the track or trunk jumps, depending on the deflection state of the deflection means, the optical pickup itself is moved across the track by a moving means consisting of a motor, rotation-linear motion conversion means, etc. move in the direction.

Next, with reference to FIG. 1, the main parts of the trunk jump control device of this optical reproducing apparatus, particularly the acceleration/deceleration pulse generation circuit, will be explained. (12) shows this acceleration/deceleration pulse generation circuit as a whole.

(3a) is a time detection means for detecting 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. (3b) is a time detection means (3a
) is a peak value calculating means that calculates the optimum peak value of the acceleration pulse based on the detection output of the acceleration pulse. Here, these means (3
a) and (3b) are time detection and peak value calculation means (3)
is represented by one block. This time detection and peak value calculation means (3) can be configured by digital calculation means (analog calculation means are also possible) such as a microcomputer.

(5) is an input terminal for a track jump command signal (for example, a positive pulse signal), and this track jump command signal is input to the time detection and peak value calculation means (3) and the R-S flip-flop circuit (8). 7 input terminals. The reset input terminal of this flip-flop circuit (8) is supplied with the detection output of a zero-cross detection circuit (2), which will be described later. The output of the non-inverting output terminal of the flip-flop circuit (8) is connected to an on-off switch (7), which will be described later.
It becomes a control signal for.

(1) is an input terminal for a tracking error signal from a tracking error detection means, and this tracking error signal is supplied to a zero cross detection circuit (2). The output of the zero cross detection circuit (2) is sent to the time detection and peak value calculation means (
3).

In the time detection and peak value calculation means (3), the input terminal (5
) from the track jump command signal from the zero-crossing detection circuit (2) and the signal indicating the zero-crossing point near the inflection point of the tracking error signal from the zero-crossing detection circuit (2), from the leading edge of the acceleration pulse to the zero-crossing point near the inflection point of the tracking error signal. The optimum peak value of the acceleration pulse to be supplied to the tracking coil is calculated based on the detected time. Note that the method of calculating this optimum peak value will be described later. (4) is an input terminal for inputting an initial value of the peak value (a value considered to be close to the optimum value) to the time detection and peak value calculation means (3). Then, this calculated peak value is sent to the D/A converter (6
) and convert it into an analog value. D/A converter (6
) is supplied to the combiner (9) via an on-off switch (7). This on/off switch (7
) is switched and controlled by the output of the flip-flop circuit (8) as described above.

(10) is a monostable multi-by break as a deceleration pulse generation circuit, and this monostable multi-by break (10
) is supplied with the output of the zero cross detection circuit (2),
Its output is fed to a combiner (9).

The synthesizer (9) synthesizes the acceleration pulse from the on-off switch (7) and the deceleration pulse, which is the inverted output of the output of the monostable multi-bi break (10), and outputs it to the output terminal (11).
The acceleration/deceleration pulses obtained are 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 the tracking error signal applied to input terminal (1). Figure 2B shows the output terminal (11
) shows the acceleration/deceleration pulses obtained. FIG. 2C shows the track jump command pulse applied to input terminal (5).

When the track jump command signal shown in FIG. 2C is supplied to the input terminal (5), the flip-flop circuit (8) is set, and the switch (7), which was off, is turned on. Become.

A tracking error signal is supplied to the input terminal (1),
The zero-crossing point near the inflection point is detected by the zero-crossing detection circuit (
2), the time detection and peak value calculation means (3) 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.

By the way, the time from the timing of the track jump command to the zero cross point near the inflection point of the tracking error signal is t, the peak value of the acceleration pulse (this becomes the drive current for the tracking coil, and the deviation of the deflection means is (proportional to acceleration) is A, and the constant is k, then the peak value A
is expressed as the following equation.

A=to/12 Now, even if the peak value of the acceleration pulse is too high, the deflection means
If it is too low, the operation will become unstable. That is, the peak value of the acceleration pulse has an optimum value for stably operating the deflection means.

Therefore, the optimum value of this peak value A is set as AO. Further, the time t at this time is assumed to be to. In this case, the time to is known, but the AO varies depending on the optical reproduction device. Thus, the following equation holds true between Ao and t0.

A(1=k/t02) Next, the time detection and peak value calculation means (3) sets the peak value A of the acceleration pulse to an arbitrary value A1, and sends the acceleration pulse having this peak value A to the tracking coil. Let tl be the time t detected from the time of the track jump command to the zero cross point near the inflection point of the tracking error signal.Thus, A1 and tl
The following equation holds true between them.

A, =ni/l, 2 From these two equations, Ao is expressed as follows.

Ao = A+ (t+ /lo) 2 Therefore, the time detection and peak value calculation means (3) performs calculation according to this formula to calculate the optimum peak value A as a digital value. This digital value is supplied to a D/A converter (6), converted into an analog value, and then supplied to a switch (7).

° to the reset input terminal of the flip-flop circuit (8).
When a zero-cross detection signal near the inflection point of the tracking error signal is supplied from the zero-cross detection circuit (2), its output is inverted and the switch (7) is turned off. Thus, the synthesizer (9) is supplied with an acceleration pulse having the optimum peak value AO and having a width corresponding to the time from the timing of the track jump command to the zero cross point near the inflection point of the tracking error signal. .

On the other hand, from the monostable multi-pie break (10), a pulse of constant amplitude and constant pulse width with a leading edge at the zero crossing point near the inflection point of the tracking error signal is obtained, which is subtractively applied to the synthesizer (9). A deceleration pulse is obtained by being supplied, this deceleration pulse is combined with the above-mentioned acceleration pulse, and the obtained acceleration/deceleration pulse is output to the output terminal (11).

This acceleration/deceleration pulse is supplied to the tracking coil of the two-axis electromagnetic drive mechanism.

As shown in FIG. 2A, the time t1 is shorter than the time T, but the time t2 can be longer than the time T.

In this way, even if the peak value of an acceleration pulse applied to the tracking coil during a certain track jump is not the optimum value, the peak value of the acceleration pulse applied to the trunking coil during the next track jump can be set to the optimum value. I can do it.

〔Effect of the invention〕

According to the present invention described above, it is possible to obtain a track jump control device for an optical recycling bag device that can quickly stabilize the operation of the deflecting means during a trunk jump.

[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. (3a) is a time detection means, (3b) is a peak value calculation means,
(3) is a time detection and peak value calculation means, and (12) is an acceleration/deceleration pulse generation circuit.

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 a detection output from the error detection means, the acceleration/deceleration pulse generation circuit comprising: time detection means for detecting 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 based on the detection output of the time detection means. A track jump control device for an optical playback device, characterized in that a track jump control device for an optical playback device is provided, comprising a peak value calculation means for calculating an optimum peak value of the acceleration pulse.