JPS6390036A - Optical information recording and reproducing device - Google Patents

Abstract

PURPOSE:To execute stable recording and reproducing and to suppress the generation of a flaw on the surface of an objective lens at its minimum by detecting a foreign substance adhering to the surface of the objective lens only at the time of defective recording/reproducing and removing the foreign substance by a brush or the like. CONSTITUTION:An objective lens driving device 2 having a strong magnetic circuit is fitted to an optical head part of an optical information recording and reproducing device and the device 2 is fitted to a dust protective case 34 to prevent the device 2 from the infiltration of dust or the like. In addition, a bush 40 for removing foreign substances adhering to the objective lens is fitted to a part of the periphery of an aperture part 36 of the case 34. Information is recorded/reproduced by the device and the laser reflection factor of an information recording medium is recorded on the inner periphery of a disk as data, and when the level of the reflection factor is dropped at the time of its reading and any trouble is generated at the time of recording/reproducing, a fixed bias voltage is applied to a focusing coil 16 and the height of the upper surface of the lens 4 is lifted up to the height of a base 12 to allow the upper surface of the lens 4 to come into contact with the brush 40 and remove a foreign substance.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an optical information recording/reproducing device that records, reproduces, or erases information by irradiating the surface of an information recording medium with a light beam. Note that the optical information recording and reproducing device herein refers to a device that only performs recording, a device that only performs playback, and a device that only performs recording.
and all devices that perform both.

[Prior Art] Conventionally, there has been an optical type in which a laser beam is irradiated onto the surface of an information recording medium in a spot shape to record information on the recording medium and/or to reproduce information recorded on the recording medium. Information recording and reproducing devices have been put into practical use.

An example of such a device is an optical disk device.

The optical disc, which is the recording medium on which information is reproduced by this optical disc device, has a width of about 1 to 2 gm and a length of about 1 gm.
An information track consisting of a row of information pits of about 3 gm is formed in a spiral shape or a concentric circle shape. When reproducing the information recorded as the information pit string, without rotating the optical disk, a laser beam is irradiated from an optical head in the form of a minute spot onto the information track of the optical disk, and the information pit string is scanned by the beam spot. let When a photodetector detects the reflected light or transmitted light of the light irradiated onto the optical disk surface in this way, the optical difference of the light incident on the photodetector depends on whether or not there is an information pit at the beam spot position. Character changes. In this way, it is possible to obtain a reproduced signal corresponding to the information pit string.

Furthermore, in such an optical disk device, it is extremely important that the minute spot always accurately scan the information bit string on the recording medium. For this purpose, auto 7 focusing is required to correct the focus shift caused by warping of the recording medium, and auto tracking is required to correct the irradiation position shift due to eccentricity of the recording medium. As a method to realize this autofocusing function and autotracking function,
Conventionally, an objective lens driving device as shown in FIG. 7 has been considered. Incidentally, FIG. 7 is an exploded perspective view showing a conventional objective lens driving device 2 for an optical head having means for auto-tracking control and auto-focusing control.

In FIG. 7, reference numeral 4 denotes an objective lens that focuses the laser beam onto the surface of the information recording medium. A holder 6 holds the objective lens 2. Reference numeral 8 provided on the holder 6 is a counterweight for determining the center of gravity of the holder. Further, a bearing 1O is provided at the center of the holder 6 to guide and support the objective lens 4 in the focusing direction and the tracking direction.

Further, the reference numeral 12 shown in the figure is a base. A shaft 14 is fixedly connected to the center of the base 12, the surface of which is coated with Teflon-based resin to reduce frictional resistance.6 This shaft corresponds to the bearing 10 described above. be. Reference numeral 16 provided at the lower end of the holder 6 is a focusing coil for driving the objective lens 4 in the focusing direction. The yaws 18a and 18b provided on the base 12 form a magnetic circuit for driving the objective lens in the focusing direction. A focusing magnet 20 is magnetized in the height direction of the cylinder.

22 and 24 are tracking magnets, respectively, and 22a
, 22b, the surfaces facing the tracking coil 26 are magnetized to N and S poles, respectively, and the surfaces of 24a and 24b, facing the tracking coil 28 (not shown), are magnetized to N and S poles, respectively. ing. 30 is a neutral holding rubber for holding the objective lens 4 in a neutral position via the holder 6, and is attached to the base 12 via a bottle 32.

The objective lens drive device configured as described above has a strong magnetic circuit and a bearing sliding part machined with high precision, so it is usually susceptible to dust from the outside.

A dustproof case 34 as shown in FIG. 8 is attached to prevent foreign matter such as dust from entering.

[Background of the Invention] However, as shown in FIG. 8, the upper surface of the objective lens 4 and the movable range of the lens in the tracking direction serve as an opening 36 for emitting a light beam.
is exposed. For this reason, foreign matter such as dirt and dust from the outside may adhere to the top surface of the objective lens. Especially if foreign matter adheres to the center of the lens, a laser spot with accurate laser power may be placed on the surface of the information recording medium. There was a drawback that irradiation could no longer be performed, causing problems in recording and reproducing information.

As a countermeasure for the above, dust on the conventional objective lens.

In order to remove foreign matter such as dust, a method has been considered in which a brush is slid on the lens every time the drive device of an optical information recording/reproducing device starts to drive, but this method By performing the above operation every time, there is a risk that unnecessary scratches or the like may be generated on the objective lens.

[Objective] The present invention prevents the occurrence of recording/reproducing defects, which are the problems described above, and also performs the operation of removing foreign matter on the four-object lens as many times as necessary. The purpose is to minimize the occurrence of scratches on the surface of the objective lens due to this operation.

[Means for solving the problem] According to the present invention, the above object is to detect an optical system and a signal level of a light beam emitted through the optical system and passed through an information recording medium and/or an error in the signal. This is achieved by an optical information recording/reproducing apparatus characterized by having means for cleaning the optical system and cleaning means for removing foreign matter adhering to the optical system based on the detected data.

[Example] Hereinafter, an example according to the present invention will be described specifically and in detail based on the drawings.

In the optical information recording and reproducing apparatus according to the present invention, an objective lens driving device 2 as shown in FIG. 7 is provided in the optical head section. The objective lens driving device 2 has a strong magnetic circuit,
Moreover, since it has a bearing sliding part that has been machined with high precision, the eighth
A dustproof case 34 as shown in the figure is attached. The dustproof case is provided with an opening 36 for emitting a light beam at a portion corresponding to the upper surface of the objective lens 4 and the movable range of the lens in the tracking direction.

Furthermore, as shown in FIG. 1, the opening 36 of the dustproof case 34
A brush 40 is provided on a part of the circumference of the objective lens 4 to remove foreign matter attached to the objective lens 4.

In the above-mentioned configuration, if a foreign substance adheres to the surface of the objective lens 4 that makes it impossible to record or reproduce information, the optical information recording/reproducing apparatus according to the present invention operates based on the flowchart shown in FIG. perform the operation. Incidentally, FIG. 2 is a flowchart showing the process of removing foreign matter adhering to the objective lens in the optical information recording/reproducing apparatus according to the present invention.

Now, if foreign matter were to adhere to a part of the surface of the objective lens, the signal balance on the detector would be disrupted and the amount of light would decrease, leading to disturbances in the tracking error signal and focusing error signal and/or a decrease in the signal level. As a result, recording/reproducing defects occur.

Hereinafter, a method of detecting the change in the signal state and a cleaning method of removing foreign matter adhering to the objective lens will be explained. The laser reflectance on the medium surface of the disk is written in advance as data on the innermost circumference of the disk, which is an information recording medium, and when the disk starts to be used, the reflectance information is read out and a predetermined signal corresponding to the reflectance is generated. If the signal level is obtained, information recording/reproducing operation is performed, and if the signal level has decreased to a level that interferes with recording/reproducing, the focusing coil 1
By applying a constant bias voltage VB to 6, the height of the top surface of the objective lens 4 is raised from A to B above the bottom surface of the base 12, as shown in FIG. Objective lens 4 or B
When the lens rises to a height of
It will touch 0.

By applying a constant voltage to the tracking coils 26 and 28, the objective lens 4 is displaced from the position M (center position) shown in FIG. It can be used to remove trash.

Next, the bias voltage VB is turned off, and recording/reproduction is performed again based on the flowchart of FIG. 2. If reproduction is again impossible, the series of operations is repeated again to remove the attached foreign matter.

The above is a description of the method for removing foreign matter adhering to the objective lens of the optical information recording/reproducing apparatus according to the present invention.

Next, another embodiment according to the present invention will be described.

FIG. 4 is a plan view of an objective lens 4 showing a second embodiment of the present invention.

In FIG. 4, 50 is a brush for removing foreign matter adhering to the surface of the objective lens 4. Reference numeral 52 denotes a brush driving section that moves the brush along the surface direction of the objective lens.

With the above configuration, recording/reproduction defects are electrically detected based on a decrease in the reproduction signal level and disc reflectance information, and a constant bias voltage Vc is applied to the focusing coil 16.
As a result, the height of the top surface of the objective lens 4 rises from the bottom surface of the base 12 from the position A to the position C, as shown in FIG. At the height C, the upper surface of the objective lens 4 comes into contact with the brush 5o. Here, by operating the brush driving section 52 and moving the brush 50 from position A to positions B and C shown in FIG. 4, the dust adhering to the surface of the objective lens 4 is removed. Next, the bias voltage ve is turned off, and the second
Perform recording and playback based on the flowchart in the figure, and if playback is not possible again, repeat the series of operations again.
Remove deposits.

FIG. 6 is a plan view of an objective lens 4 showing a third embodiment of the present invention.

In FIG. 6, 60 is a brush for removing foreign matter adhering to the surface of the objective lens 4. 62 is a head. 6
4 and 66 are shafts that support the head 62 so that it can be moved in the access direction. 68 is a linear motor that moves the head 62 in the access direction. 70 is a turntable on which a disk is placed and rotated.

With such a configuration, recording/reproducing defects are electrically detected based on a drop in the reproduction signal level and disc reflectance information, and a constant bias voltage vc is applied to the focusing coil 16.

As shown in FIG. 5, the height of the top surface of the objective lens 4 is
rises from the bottom of the screen from A to C. At the height C, the upper surface of the objective lens 4 comes into contact with the brush 6o. Here, the head 62 is moved by the linear motor 68, and by moving it from the normal movement range between A and 8 to the position C from the turntable 7o, the objective lens 4
Debris on the surface is brushed away. Next is the bias voltage ■. Recording and reproduction are performed again based on the flowchart in FIG. 2, and if reproduction is not possible again, the series of operations is repeated again to remove the deposits.

Further, in the above description, the objective lens was used as an example of the optical system, but the present invention is not limited to this, and other optical systems are also included.

[Effects of the Invention] As described above in detail and concretely, according to the present invention, foreign matter attached to the objective lens surface is detected only when there is a recording/reproduction failure, and is removed with a brush or the like, thereby stably recording/reproducing. In addition to being able to perform regeneration, the brush does not come into contact with the objective lens unnecessarily, making it possible to minimize the occurrence of scratches on the lens surface.

[Brief explanation of the drawing]

1 and 8 are plan views of the dustproof case. ff4
FIG. 2 is a flowchart showing the process of removing foreign matter attached to the objective lens. 3 and 5 are side views of the objective lens driving device. 4 and 6 are plan views of the objective lens. FIG. 7 is an exploded perspective view of the objective lens driving device. 4...Objective lens 34--Dust-proof case 36...Opening 40...Brush agent Patent attorney Seki Yamashita Figure 1 Figure 2 Figure 3 Figure 4 Figure 5

Claims (1)

[Claims] (1) an optical system, a means for detecting the signal level of a light beam emitted through the optical system and passing through an information recording medium and/or an error in the signal; and a means for detecting an error in the signal based on the detected data. 1. An optical information recording and reproducing device, comprising a cleaning means for removing foreign matter adhering to the optical information recording and reproducing device.