JPH04325928A - Optical information recording and reproducing device - Google Patents

Abstract

PURPOSE:To execute stable tracking with simple configuration by resolving problems such as increasing cost by providing the two systems of focusing and tracking for the lens actuator of an optical head and generating the mechanical resonance of a linear motor or the complicated constitution of a control circuit by providing the two kinds of the linear motor and the lens actuator as the tracking follow-up means of the optical head at the optical information recording and reproducing device such as a compact disk device having much information quantity or a CD-ROM device. CONSTITUTION:The lens actuator of the optical head is supported so as to be moved only vertically to a disk 1, and the information of a driving circuit 7 of an optical head 2 and information detected by a position sensor 2 of the optical head are inputted to an observer 15. Then, since this observer 15 estimates the velocity of the optical head 2 and impresses the output of the observer 15 to the device circuit 7 of the optical head 2, stable tracking can be executed with simple configuration.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical information recording/reproducing apparatus such as a compact disk device, CD-ROM device, etc., which has a large information capacity.

0002

[Prior Art] A conventional optical information recording/reproducing device is shown in FIG.
Shown in FIGS. 9 and 10. FIG. 8 is a side view of essential parts of a conventional optical information recording/reproducing apparatus, FIG. 9 is a block diagram of an access servo system, and FIG. 10 is a block diagram of a tracking servo system. In FIG. 8, 1 is a disk for recording information, 2 is an optical head for recording and reproducing information, and 20 is an objective lens held movably in the radial and vertical directions at a position facing the disk 1 in the optical head 2. , 21 is a lens actuator for generating a moving force for moving the disk 1 in the radial and vertical directions; 4 is an optical head 2;
5 is a position sensor for detecting the position of the optical head 2. In FIG. 9, 3 is a linear motor for moving the optical head 2 in the radial direction of the disk 1, 6 is a position sensor for detecting the position of the objective lens 20, and 7 is a linear motor for moving the optical head 2 in the radial direction of the disk 1;
8 is a drive circuit for the linear motor 3, 8 is a drive circuit for the lens actuator 21, and 9 and 10 are first and second filters. In FIG. 10, 11 is a photodetector for detecting the amount of error in the position of the optical head 2 in the disk radial direction;
2 and 13 are third and fourth filters.

[0003] The access to a target track and the tracking operation of the optical information recording/reproducing apparatus configured as described above will be explained.

In the access servo system shown in FIG. 9, the access servo uses the thrust of the linear motor 3 in the radial direction of the disk 1 to record and reproduce information recorded on the disk 1. means to move to the target position. The input of the target position to the access servo system is input to the first drive circuit 7 through the first filter 9 . The first drive circuit 7 is a linear motor 3
output and supply a drive current to drive the linear motor 3,
An optical head 2 is driven by a linear motor 3. The first position sensor 5 of the optical head 2 feeds back the current position information of the driven optical head 2 to the access servo system, and the access servo system compares it with the target position and adjusts the drive amount of the linear motor 3. The optical head 2 is driven to the target position. During access, large acceleration is applied to the optical head 2 in the tracking direction during acceleration and deceleration. Therefore, the second position sensor 6 detects the position of the objective lens 20, and the position servo system electrically fixes the objective lens 20 so that it does not vibrate during access.

Next, referring to the tracking servo system shown in FIG. 10, tracking means making the optical head 2 follow a track prepared in advance on the disk 1. The amount of deviation from the disk track is detected by a photodetector 11 within the optical head 2, and is input as an error signal to the tracking servo system. This error signal is the third
, are applied to the fourth filters 12 and 13. If the frequency band is high, the error signal is output from the third filter 12 to drive the lens actuator 21, and if the frequency band is low, it is output from the fourth filter 13 to drive the linear motor 3, respectively. The tracking servo system is driven by drive circuits 8 and 7 of No. 1, and operates so as to set the error signal to 0.
The optical head 2 is made to follow the disk track.

[0006]

[Problems to be Solved by the Invention] However, in the above configuration, the lens actuator of the optical head has two systems, focusing and tracking, so the configuration of the optical head is complicated, and the number of assembly steps and component parts is increased. This increases the cost.

Furthermore, during tracking, there are two types of means for following the optical head in the tracking direction: a linear motor and a lens actuator.Since the servo system becomes unstable due to the mechanical resonance of the linear motor, the tracking control The servo loop also requires two stages depending on the frequency band, and the control circuit becomes complicated.

In addition, the objective lens tends to vibrate when the optical head is accessed, and in order to fix the objective lens, a position sensor is provided near the objective lens to perform position servo in the tracking direction, and furthermore, the optical head and control circuit are complicated. I have to.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an optical information recording/reproducing device which can eliminate the above-mentioned conventional drawbacks and which can simplify the configuration and circuitry.

0010

[Means for Solving the Problems] In order to solve the above problems, the present invention supports a lens actuator of an optical head so as to be movable only in a direction perpendicular to an information recording medium, and provides information on a drive circuit of the optical head. The apparatus includes an observation device that inputs information detected by the position detection means of the optical head, and has a configuration in which the observation device estimates the speed of the optical head and adds the output of the observation device to the drive circuit of the optical head.

[0011]

[Operation] With the above-described configuration, the present invention suppresses mechanical resonance of the optical head moving means by feeding back the estimated speed output from the observation device to the drive circuit, and controls the servo loop of the optical head at several KHz or more. Since it can operate stably up to a high frequency band, it is possible to perform tracking using only the means for moving the optical head in the radial direction of the medium, and it also enables high access without the need for a position sensor for the objective lens.

0012

[Embodiment] An embodiment of the present invention will be described below. FIG. 1 is a configuration diagram of a main part of an embodiment of the present invention, FIG. 2 is a side view of the main part, FIG. 3 is a block diagram showing an access servo system, and FIG.
FIG. 2 is a block diagram showing a tracking servo system. 1 and 2, 1 is a disk as an information recording medium, 2 is an optical head, 20 is an objective lens that is held movable only in the vertical direction of the disk 1, 22 is a lens actuator, and 3 is a movement of the optical head 2. 4 is a support mechanism for the optical head 2, and 5 is a position sensor as a position detection means for the optical head 2.

In FIG. 3, 14 is a first filter;
is the drive circuit of the linear motor 3, and in FIG.
1 is a photodetector that detects a tracking error signal; 15 is a photodetector that receives the position information of the position sensor 5 and the drive information of the linear motor 3 from the drive circuit 7;
16 is a second filter that outputs an estimated value of the moving speed.

The access to the target position and tracking operation of the optical information recording/reproducing apparatus configured as above will be explained.

In the access servo system shown in FIG. 3, the input of the target position is input to the drive circuit 7 through the first filter 14, and the linear motor 3 is driven. This is a servo system that tracks the target position by feeding back the absolute position of the optical head 2 detected by the position sensor 5. This configuration is almost the same as that of a conventional optical information recording/reproducing device, but the objective lens 20 has a tracking direction. Since there is no lens actuator and the objective lens 20 is fixed in the tracking direction, a position servo system for the objective lens 20 during access is not configured.

Next, regarding the tracking servo system shown in FIG. 4, the amount of deviation of the optical head 2 from the disk track is detected by the photodetector 11 as an error signal, and is input to the tracking servo system. The error signal is input to the drive circuit 7 through the second filter 16, and the linear motor 3 is driven. The relative position information of the optical head 2 with respect to the disk 1 from the drive circuit 7 of the linear motor 3 and the absolute position information of the optical head 2 from the position sensor 5 are input to the observation device 15. Estimate the speed of 2. Since the estimated speed that is the output of the observation device 15 is fed back to the drive circuit 7, the mechanical resonance of the servo system can be suppressed, the tracking band can be increased, and tracking up to a high band can be performed using only the linear motor 3. Perform stable tracking.

Next, FIG. 5 shows a second embodiment of the present invention.
~Explained using FIG. 7. FIG. 5 is a side view of a main part of the second embodiment, FIG. 6 is a block diagram showing an access servo system of the same device, and FIG. 7 is a block diagram showing a tracking servo system of the same device. In FIGS. 5 to 7, the same components as those in FIGS. 1 to 4 are given the same numbers and detailed explanations are omitted.

This second embodiment differs from the first embodiment in that the support mechanism 17 for the optical head 2 is inclined with respect to the vertical direction of the disk 1, and that the position sensor for the optical head 2 Therefore, the configuration is such that the drive current for the lens actuator 23 is provided in the block diagrams of the servo system shown in FIGS. 6 and 7.

The access and tracking operations of the optical information recording/reproducing apparatus configured as above will be explained.

In the access servo system shown in FIG. 6, the input of the target position is input to the drive circuit 7 through the first filter 18, and the linear motor 3 is driven. So far, the first
This embodiment is similar to the embodiment described above, but instead of the position sensor 5 of FIG. 3 detecting the absolute position of the optical head 2, the drive current of the lens actuator 23 is detected and converted into the absolute position of the optical head 2. As shown in FIG. 5, since the support mechanism 17 that supports the optical head 2 is tilted with respect to the vertical direction of the disk 1, the lens actuator 23 follows the tilt and adjusts to the position in order to keep the focus position constant. Since this requires a driving current, it becomes absolute position information of the optical head 2. This is an access servo system that feeds back the current position of the optical head 2 and follows the target position.

In the tracking servo system shown in FIG. 7, the amount of deviation of the optical head 2 from the disk format is detected by the photodetector 11 as an error signal, and is input to the tracking servo system. The error signal is passed through the second filter 1
9 and is input to the drive circuit 7 to drive the linear motor 3. This is the same as the first embodiment, except that the absolute position of the optical head 2, which is input to the observation device 25, is obtained by detecting the driving current of the lens actuator 23, as in the case of access. Only the absolute position of the optical head 2 is available.

In the second embodiment configured as described above, the support mechanism 17 for the optical head 2 is tilted, so that the optical head 2 can be moved without using the position sensor conventionally used for detecting the position of the optical head. can detect the position of

[0023]

As is clear from the description of the embodiments above, the present invention includes an observation device for inputting the drive current of the moving means and the position information of the optical head in the tracking servo loop of the optical head. By feeding back the estimated speed of the optical head to the drive circuit, the tracking range of the optical head moving means can be increased to a higher band, even down to minute ranges.

Therefore, the lens actuator in the optical head can be fixed in the radial direction of the medium, the structure of the optical head can be simplified, and the servo circuit for control can be simplified to just one stage.

Furthermore, since the objective lens is fixed in the radial direction of the medium, it is naturally strong against vibrations of the objective lens in the radial direction of the medium after the optical head moves. This also leads to improved access time.

Furthermore, if the position detecting means of the optical head is configured to use the driving current of the lens actuator, a position sensor for the optical head is not required, which is an advantageous method that is inexpensive and can also realize miniaturization of the device. An optical information recording/reproducing device is provided.

[Brief explanation of the drawing]

FIG. 1 is a main part configuration diagram showing an optical information recording/reproducing device according to a first embodiment of the present invention.

[Figure 2] Side view of main parts of the device

[Figure 3] Block diagram of the access servo system of the device

[Figure 4
] Block diagram of the tracking servo system of the device

[Figure 5]
A side view of main parts of an optical information recording/reproducing device according to a second embodiment of the present invention

[Figure 6] Block diagram of the access servo system of the device

[Figure 7
] Block diagram of the tracking servo system of the device

[Figure 8]
Side view of main parts of a conventional optical information recording/reproducing device

[Figure 9] (
a) and (b) are block diagrams of the access servo system of the same device.

[Figure 10] Block diagram of the tracking servo system of the device

[Explanation of symbols]

1 Disk 2 Optical head 3 Linear motor 4 Support mechanism 5, 6 Position sensor 7, 8 Drive circuit 9, 10 Filter 11 Photodetector 12, 13, 14 Filter 15 Observer 16 Filter 17 Support mechanism 18, 19 Filter 20 Objective lens 21, 22, 23 Lens actuator 25 Observation device

Claims (2)

[Claims] 1. An information recording medium, an optical head for recording and reproducing information from the information recording medium, and having an objective lens movable only in a direction perpendicular to the information recording medium, and the optical head in a radial direction of the medium. a moving means for moving the optical head in the medium radial direction; a drive circuit for driving the moving means; An optical information recording/reproducing device comprising an observation device for inputting position information of an optical head, and configured to add an output of the observation device to the drive circuit. 2. The position detecting means of the optical head in the medium radial direction includes support means having a constant inclination in the direction perpendicular to the information recording medium, and the drive current of the lens of the optical head in the direction perpendicular to the medium is provided. The optical information recording and reproducing apparatus according to claim 1, which is configured to detect.