JPH03260971A - tracking control device - Google Patents

Abstract

PURPOSE:To suppress the oscillation of an objective lens and to prevent a track count error occurring by applying velocity control to the objective lens when a tracking servo loop is set at an open state while a pickup is being moved and external oscillation is added. CONSTITUTION:When the pickup 6 is moved, a speed loop switch 15 is closed, and the velocity control is applied to a tracking actuator 5. A pickup travel speed signal from a speed detecting means 12 is used as a reference signal inputted to a speed comparison means 14, and the means 14 outputs a velocity control pulse to a driving means 4, and sets the speed of the objective lens traversing a track at the same speed as the travel speed of the pickup. Therefore, the oscillation of the objective lens in the pickup 6 can be suppressed, and the output waveform of an error detecting means 1 goes to a cross synchronous waveform with equal gap. In such a way, no influence of the external oscillation is included in a tracking error waveform, and no track count error occurs.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a tracking control device for optical discs and the like.

2. Description of the Related Art In recent years, technological advances in optical disk devices have been remarkable, but a tracking operation that can withstand external vibrations is an important issue for these devices.

The configuration of a conventional tracking control device is shown in a block diagram in FIG. In the figure, 1 is a tracking error detection means, 2 is a servo amplifier circuit, 3 is a loop switch, 4 is a tracking drive means, 5 is a tracking actuator, 6 is a pickup having an objective lens inside, 7 is a traverse actuator, and 8 is a traverse drive means,
Reference numeral 9 denotes a control means comprising a microcomputer, 10 an information medium having track information therein, and 11 a track cross counter.

To explain the mutual relationship and operation of each component of the above-mentioned conventional tracking control device, the operation when accessing a target track from an arbitrary track first involves switching the loop switch 3 using a loop switch control signal from the control means 9. Open it and put the tracking servo in the oven state. Next, the control means 9 gives a drive command to the traverse drive means 8,
The traverse drive means 8 operates the traverse actuator 7 to move the pickup 6. The control means 9 calculates the number of tracks between the arbitrary track and the target track,
A track count signal outputted from a track cross counter 11 corresponding to the number of tracks crossed is compared, and when the two match, a stop command is issued to a traverse drive means 8 to stop the movement of the pickup 6. When the pickup 6 stops near the target track, the control means 9 sends the loop switch control signal to the loop switch 3 again, the loop switch 3 is closed, and the tracking servo is pulled in. When the tracking servo is pulled in and the servo operates normally, it becomes possible to read information and move on to the next arbitrary operation.

Problems to be Solved by the Invention In such a conventional tracking control device, the tracking servo is in an oven state while the pickup 6 is moving, so when external vibrations are applied to the pickup 6, the objective lens inside the pickup 6 is in a vibrating state. becomes. When the objective lens is in a vibrating state, the number of times it crosses the track increases, and the track counter 11 outputs an erroneous track count signal to the control means 9 that is greater than the number of tracks actually crossed during the traverse operation, and the control means 9 picks up the track. 6
Although it is located far from the target track,
A stop command is given to the traverse drive means 8. Therefore, it is necessary to perform the access operation again, resulting in an increase in access time.

The present invention solves the above problems, and when accessing, even if external vibrations are applied while the pickup 6 is moving, the present invention suppresses the vibration of the objective lens and prevents rack count errors. The purpose is to provide

Means for Solving the Problems In order to solve the above problems, the present invention provides a traverse speed detection means, a cross speed detection means, a speed comparison means, and a speed loop switch in addition to the conventional tracking servo loop. The configuration includes the following.

Effect The present invention has the above-described configuration, so that while the pickup is moving,
When the tracking servo loop is in an oven state and external vibrations are applied, speed control is applied to the objective lens.

Embodiment Hereinafter, a tracking control device according to an embodiment of the present invention will be explained with reference to FIGS. 1 and 2.

FIG. 1 shows a block diagram of the configuration of a tracking control device according to an embodiment of the present invention.

In FIG. 1, parts that are the same as those shown in FIG. 3 are given the same numbers and their explanations will be omitted.

In FIG. 1, 12 is a traverse speed detecting means, 13 is a cross speed detecting means for detecting the relative speed at which the objective lens crosses the track of the information medium from a tracking error signal, and 14 is a speed output from the cross speed detecting means (3). Speed comparison means 15 is a speed loop switch which compares the signal with the output signal from the traverse speed detection means 12 and outputs a speed control pulse.

Figure 2 shows the output waveforms of the tracking error detection means 1 when the pickup 6 is moving during access and external vibration is applied, where (a) is no speed control and (b) is the speed Corresponds to control.

Next, the mutual relationship and operation of each component will be explained. When an external signal is applied while the pickup 6 is moving, the objective lens inside the pickup 6 vibrates, so the output signal of the tracking error detection means 1 is This appears as an irregular track cross cycle waveform as shown in Figure (a). This indicates the possibility that the objective lens may cross the same track multiple times.

In this embodiment, when the pickup 6 moves, the speed loop switch 15 is closed by a command from the control means 9,
Speed control is applied to the tracking actuator 5. The speed comparison means 14 uses the Pisocqua knob movement speed signal output from the traverse speed detection means 12 as a reference signal input to the speed comparison means 14, and the speed comparison means 14 detects that the speed at which the objective lens crosses the track is the same as the pickup movement speed. A speed control pulse is output to the tracking drive means 4 in this manner. With this control, even if the objective lens in the pickup 6 tries to vibrate due to an external signal, the vibration is suppressed because the speed is controlled to be constant in accordance with the traverse speed, and the output waveform of the tracking error detection means 1 is as shown in Figure 2. As shown in (b), this results in a cross cycle waveform with equal intervals.

The loop switch 3 connects the output of the servo amplifier circuit 2 to the tracking drive means 4 in response to the stop of the pickup 6, and the speed loop switch 15 disconnects the control signal in response to the start of retraction of the tracking servo. Then, the vibration control operation ends.

As described above, according to the tracking control device of one embodiment of the present invention, in addition to the conventional tracking control loop, the traverse speed detection means 12 and the cross speed detection means 13 are added.
, a speed comparison means 14, and a speed loop switch 15. The speed at which the objective lens crosses the track, that is, the cross speed, is detected from the error signal and outputted to the speed comparison means 14, and the speed comparison means 14 compares the cross speed and the traverse speed, and calculates the difference between them. A corresponding control pulse (control signal) is output to the tracking drive means 4 via the speed loop switch 15, and the speed loop switch 15 outputs the control signal to the tracking drive means 4 in response to the start of the access operation. It is connected to a driving means 4 and disconnected in response to the start of retraction of the tracking servo, and the tracking driving means 4 inputs the control signal and drives the objective lens so that the cross speed matches the traverse speed. With this configuration, even if the pickup 6 receives external vibration during the access operation, the objective lens is controlled to cross the track at a speed that matches the Tohaas speed, suppressing lens vibration and inputting it to the track counter. Since the tracking error waveform does not include the influence of external vibration, it is possible to obtain the effect that no track count error occurs.

Effects of the Invention As is clear from the above embodiments, the tracking control device of the present invention has the advantage of improving the traverse speed in addition to the conventional tracking control device equipped with a tracking control loop including a tracking drive means and a tracking error detection means. A detection means, a cross speed detection means, a speed comparison means, and a speed lube are provided, the traverse speed detection means detects the traverse speed of the pickup and outputs it to the speed comparison means, and the cross speed detection means detects the traverse speed of the pickup and outputs it to the speed comparison means. The speed at which the lens crosses the track, that is, the cross speed, is detected from the tracking error signal of the tracking error detection means and outputted to the speed comparison means, and the speed comparison means compares the cross speed and the traverse speed, and outputs the detected speed to the speed comparison means. A control signal corresponding to the difference is outputted to the tracking drive means via the speed loop switch, and the speed loop switch connects the control signal to the tracking drive means in response to the start of the access operation and pulls in the servo. The tracking drive means inputs the control signal and drives the objective lens so that the cross speed matches the traverse speed, thereby cutting the pickup during the access operation. Even if the objective lens receives external vibration, the objective lens is controlled to cross the track at a speed that matches the traverse speed, suppressing lens vibration, and the tracking error waveform input to the track counter does not include the influence of external vibration. It is possible to obtain the effect that no track error occurs.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of a tracking control device according to an embodiment of the present invention, FIG. 2 is a waveform diagram of a tracking error signal, and FIG. 3 is a block diagram showing the configuration of a conventional tracking control device. be. 1... Tracking error detection means, 2...
... Servo amplifier circuit, 3 ... Loop switch, 4 ... Tracking drive means, 5 ...
・Tracking actuator, 6...Pickup, 7...Traverse actuator, 8
... Traverse drive means, 9 ... Control means, 10 ... Recording medium, 11 ... To-to-tsuku cross counter, 12 ...・Traverse speed detection means, 13...Cross speed detection means,
14... Speed comparison means, 15... Speed loop switch.

Claims (1)

[Claims] A pickup that includes a control means, a loop switch and a speed loop switch controlled by the control means, and a tracking drive means, and that optically reads information from a recording medium, and an objective lens included in the pickup that reads information on the recording medium. a tracking actuator that moves in a direction perpendicular to the track direction as a column; a tracking error detection means that is connected to the pickup and detects a positional deviation between the track and the optical spot of the pickup and outputs a tracking error signal; a surp amplifier circuit that amplifies the tracking error signal and outputs it to the tracking drive means via the loop switch; a traverse actuator that moves the pickup in a direction perpendicular to the track direction; and a traverse actuator that is controlled by the control means. a traverse drive means for driving the track according to the tracking error signal; a track cross counter for inputting the tracking error signal to count the number of times the optical spot crosses the track and outputting the counted number to the control means; cross speed detection means for detecting the speed at which the light spot crosses the track and outputting the cross speed; traverse speed detecting means for detecting the moving speed of the traverse actuator and outputting the traverse moving speed; and the cross speed. and speed comparison means for inputting the traverse speed and outputting a control signal corresponding to the difference to the traverse drive means via the speed loop switch, and the tracking drive means inputs the tracking error signal. The control means drives the objective lens so that the tracking error becomes zero and the cross speed matches the traverse speed by inputting the control signal, and the control means drives the objective lens in response to the start of the access operation of the apparatus. The speed switch connects the control signal to the tracking drive means, the loop switch disconnects the servo amplifier output, and the loop switch connects the servo amplifier output to the tracking drive means in response to the stop of the pickup. . A tracking control device configured to cut off the control signal with the speed switch in response to the start of retraction of the tracking servo.