JP2737228B2 - Tracking control device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used for an optical disk reproducing apparatus for projecting a light beam onto a disk to perform recording and reproduction.

2. Description of the Related Art Information is recorded on a spiral track on a disc.
When performing fast-forward playback while playing back some information tracks, a pulse is input to the objective lens driving device to perform a track jump operation that crosses one to several hundred tracks in one jump.

Hereinafter, a conventional tracking control device will be described. FIG. 5 is a diagram showing the configuration of the mechanism system. The disk 1 is rotated by a spindle motor 4. Reference numeral 2 denotes an objective lens, reference numeral 3 denotes an optical pickup including an objective lens driving device, and reference numeral 5 denotes a feed motor for moving the optical pickup 3 in the radial direction of the disk 1.

FIG. 6 is a block diagram showing a configuration of a control circuit in a conventional tracking control device. Optical pickup 3
A tracking error signal is generated by the comparison amplifier 7 using the output of the light receiving element 6 and the phase compensation is further performed by the equalizer 8, and then amplified by the driving amplifier 9 and input to the tracking driving coil 10; Performs a tracking servo for tracking the light beam on the track of the disk. Since the tracks on the disk have a spiral shape from the inside to the outside, the objective lens is gradually sent to the outer periphery of the disk in continuous reproduction. At this time, it is necessary to feed the optical pickup 3 toward the outer periphery of the disk so that the objective lens driving device does not exceed the tracking D range in which the objective lens can move. For this reason, a component close to DC of the voltage of the tracking drive coil 10 is extracted by a low-pass filter (LPF) 11, amplified by the drive amplifier 12, added to the feed motor 5, and added to the optical pickup 3.
To move. That is, the objective lens driving device follows the minute displacement of the track due to the disk eccentricity, etc. The optical pickup 3 is caused to follow by driving the feed motor 5 and moving the optical pickup 3. When accessing the target track or performing fast-forward reproduction, the microcomputer 13 performs a track jump operation by controlling the polarity and duration of the pulse output of the pulse generator 14.

FIG. 7 shows the voltage V _C of the tracking drive coil at the time of the track jump operation for jumping 150 tracks at a time to explain the track jump operation. In the range A, the tracking servo loop is still closed. A tracking servo loop is opened at point E, and a track jump operation is started. The section B is an acceleration pulse and the section C is a deceleration pulse. At a point F, the tracking servo loop is closed, and the track jump operation is completed. This operation is repeated as one cycle until there is an instruction to end the track jump operation.

However, in the above-described conventional configuration, when the above-described track jump operation is intermittently repeated, or when the optical pickup cannot be sent sufficiently due to a variation in load of a feeder of the optical pickup including the feed motor 5. The objective lens 2 precedes the position of the optical pickup 3 in the jump direction too much and exceeds the D range of the objective lens driving device. In this objective lens driving device, the movable portion holding the objective lens 2 is fixed. There is a problem that the focus servo of the two-dimensional objective lens driving device is disengaged by colliding with the stopper, and that the objective lens 2 hits the disk and may damage the disk.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described conventional problems, and has a simple configuration to prevent a movable portion holding an objective lens from colliding with a stopper of a fixed portion in an objective lens driving device, thereby achieving focus. It is an object of the present invention to provide a tracking control device in which the objective lens does not hit the disk without damaging the servo and damages the disk.

Means for Solving the Problems In order to solve the above problems, the tracking control device of the present invention detects the displacement of the objective lens when performing a track jump operation intermittently, and when the displacement exceeds a certain set value, This stops or prohibits the track jump operation.

Operation The operation of the present invention according to the above configuration is as follows. That is, when the track jump operation is performed intermittently, the displacement of the objective lens is detected, and when the displacement exceeds a certain set value, the track jump operation is stopped or inhibited, so that the objective lens is driven by the objective lens driving device. This prevents the held movable portion from colliding with the stopper of the fixed portion, and prevents the focus servo from coming off, so that the objective lens does not collide with the disk and damage the disk.

Embodiment FIG. 1 is a diagram showing a configuration of a mechanism system of a tracking control device according to an embodiment of the present invention, which has the same configuration as that of a conventional example. The disk 21 is rotated by the spindle motor 24, and the optical pickup 23 can be moved in the radial direction of the disk 21 by the feed motor 25. 22 is an objective lens.

FIG. 2 is a block diagram showing a configuration of a control circuit of the tracking control device according to one embodiment of the present invention. A tracking error signal is generated by a comparison amplifier 27 using the output of the light receiving element 26 of the optical pickup 23, and phase compensation is further performed by an equalizer 28. A tracking servo is performed so that the light beam of the lens 22 tracks on the track of the disk. Further, in order not to exceed the D range that can be tracked in the objective lens driving device, the voltage of the tracking driving coil 30 is extracted by a low-pass filter (LPF) 31 to a component close to direct current, amplified by a driving amplifier 32 and fed to a feed motor 25. Optical pickup at 23
In the radial direction of the disk. When accessing the target track or performing fast forward playback, the microcomputer 35 controls the polarity and duration of the pulse output of the pulse generator 36, amplifies this signal with the drive amplifier 29, and drives the tracking drive coil. To perform a track jump operation. At this time, the tracking drive coil
_A low-pass filter (LP
F) Take out at 33, input to window comparator 34,
The voltage V _A is the output voltage V _B of the window comparator 34 when it is time or V _RL less equal to or higher than the reference voltage V _RH is set beforehand becomes high. Also when the voltage V _A is between _RH reference voltage V _RL and V, the output voltage V _B of the window comparator 34 goes low. It reads the output voltage V _B by the microcomputer 35, when high, stops or prohibits the operation of the pulse generator 36, when low, enables operation of the pulse generator 36.

The operation of the tracking control device of the present embodiment configured as described above will be described below. The operation of the window comparator 34 of this embodiment will be described with reference to FIG.
When the output voltage V _{A of the} low-pass filter (LPF) 33 becomes equal to or higher than the preset reference voltage V _RH or equal to or lower than the reference voltage V _RL , the output voltage V _B of the window comparator 34 becomes high and the low-pass filter (LPF) 33 When the output voltage V _a is between _RH reference voltage V _RL and V, the output voltage V _B of the window comparator will be low.

FIG. 4 is a flowchart of a main part for explaining the operation of the microcomputer 35 of the present embodiment. When a track jump operation is commanded by an external input of the microcomputer 35, the execution of this subroutine program is started in step 37. First, at step 38, the pulse generator 36 is operated. In step 39, it is checked whether there is a tracking jump operation end command. If there is, the operation of the pulse generator 36 is stopped in step 40, and the subroutine program is ended in step 41. If there is no end instruction at step 39 to go to step 42, the output voltage V _B of the window comparator 34 to check whether high or low. If it is high, the operation of the pulse generator 36 is stopped in step 43, and if it is low, the operation of the pulse generator 36 is restarted in step 44, and the process returns to step 39. In this way, the operation of the pulse generator 36 is stopped and restarted by the output of the window comparator 34 until a command to end the track jump operation is issued.

As described above, according to the present embodiment, when the track jump operation is performed intermittently, the displacement of the objective lens 22 is detected by a component of the voltage of the tracking driving coil 30 close to the direct current, and the displacement is set to a certain value. By stopping or inhibiting the track jump operation, the movable portion holding the objective lens in the objective lens driving device is prevented from colliding with the stopper of the fixed portion, and the focus servo is not disengaged. The effect is very large because the objective lens does not hit the disk and damage the disk.

As described above, the present invention provides an objective lens for converging a light beam on a disk, and an objective lens driving device capable of displacing the objective lens in at least two directions of a perpendicular direction and a radial direction with respect to the disk. Tracking servo means for tracking the light beam on the information track of the disk; feed means for sequentially changing the relative position between the disk and the objective lens driving device in the radial direction of the disk; and the objective lens A pulse generator for inputting a pulse to a driving device to cause a light beam emitted from the objective lens to irradiate the disk to cause a track jump in a radial direction of the disk; and a displacement of the objective lens in the objective lens driving device in the radial direction of the disk. Detecting means for detecting, and detecting a voltage based on displacement of the objective lens by the detecting means. Comparing means for determining whether the output of the pulse generator is out of the reference voltage range, and control means for stopping the output of the pulse generator when the output of the comparing means is out of the reference voltage range. When the track jump is performed intermittently, the output of the pulse generator is stopped when the voltage based on the detection means falls outside the reference voltage range set by the comparison means. Prevents the movable part being held from colliding with the stopper of the fixed part, so that the focus servo does not come off, so that the reproduction of the disk does not stop, and the objective lens does not hit the disk and damage the disk. A tracking control device capable of obtaining excellent effects can be realized.

[Brief description of the drawings]

FIG. 1 is a side view showing a configuration of a mechanism system of a tracking control device according to an embodiment of the present invention, FIG. 2 is a block diagram showing a configuration of the control circuit, and FIG. 3 is a window comparator of the control circuit. FIG. 4 is a waveform diagram for explaining the operation of FIG. 4, and FIG.
FIG. 5 is a side view showing a configuration of a mechanism system of a conventional tracking control device, FIG. 6 is a block diagram showing a configuration of the control circuit, and FIG. 7 is a waveform diagram for explaining a track jump operation. 21 ... Disc, 22 ... Objective lens, 23 ... Optical pickup, 24 ... Spindle motor, 25 ... Feed motor, 30
... Tracking drive coil, 33 ... Low-pass filter, 34 ... Window comparator, 35 ... Microcomputer, 36 ... Pulse generator.

Claims (2)

(57) [Claims] 1. An objective lens for converging a light beam on a disk, an objective lens driving device capable of displacing the objective lens in at least two directions perpendicular and radial to the disk, and an information track on the disk A tracking servo unit for tracking the light beam on the top, a feed unit for sequentially changing a relative position between the disk and the objective lens driving device in a radial direction of the disk, and a pulse input to the objective lens driving device. A pulse generator for causing the objective lens to perform a track jump in a radial direction of the disk with a light beam irradiated on the disk;
Detecting means for detecting a radial displacement of the disk of the objective lens in the objective lens driving device, and extracting a voltage based on the displacement of the objective lens by the detecting means and comparing whether or not the voltage is within a preset reference voltage range; Comparing means, and control means for stopping the output of the pulse generator when the output of the comparing means is outside the reference voltage range, the control means, when performing intermittent track jump,
When the voltage based on the detecting means is out of the reference voltage range set by the comparing means, the output of the pulse generator is stopped. 2. The tracking control device according to claim 1, wherein said detection means uses a DC component of a voltage between both ends of a tracking driving coil in said objective lens driving device.