JPH02203434A - Optical head having separate actuator - Google Patents

Abstract

PURPOSE:To eliminate the influence of the dust within a disk drive device by covering a laser light incident window of an actuator part and a laser light radiation window of a main body fixing part with a transparent plate which can transmit the laser light. CONSTITUTION:A laser light incident window 23 of an actuator part 20 and a laser light radiation window 120 of a main body fixing part 10 are covered with a transparent plate 30 which can transmit the laser light. The plate 30 is made of a transparent material like the plane glass or plastic, etc. Thus the plate 30 covering both windows 23 and 120 transmits freely the laser light and prevents surely the mixture of the dust. Then the mixture of the dust is suppressed to the part 10 and the mobile part 20. As a result, the influence of the dust is extremely reduced to an optical system.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to an actuator-separated optical system in which an actuator part supporting an objective lens is a movable part, and a main body head part to which optical components including a semiconductor laser are assembled is a fixed part. Regarding the head.

2. Description of the Related Art Optical discs are recording media with excellent features such as large capacity, non-contact, and interchangeable media, and are attracting attention as optical disc files and external storage media for computers.

As is well known, such optical discs record or reproduce information using an optical head using a semiconductor laser, and depending on the medium, the recorded information can be erased or rewritten. In this type of optical head, high-speed access is considered to be an extremely important element.

However, since optical heads are larger and heavier than magnetic heads used for magnetic recording, they have been said to be unsuitable for high-speed access.

In order to solve this problem, we formed a fixed optical system using various optical system parts including a semiconductor laser, and installed and fixed this on the chassis base, while incorporating a relatively lightweight objective lens actuator section into the fixed optical system. An actuator-separated optical head has been proposed in which the actuator is separated from the main body head portion and only this actuator portion is moved in the disk radial direction. This makes it possible to access much faster than the conventional optical head that moves the entire head.

Problems to be Solved by the Invention However, in order to introduce the laser beam emitted from the semiconductor laser of the fixed optical system into the actuator section and guide it to the objective lens, it is necessary to use opposing parts on the laser beam optical path between the actuator section and the main body fixed section. An entrance window and an exit window for the laser beam must be formed. These entrance windows and exit windows are always open not only when the optical head is in operation, but also at other times, so dirt and dust floating inside the disk drive device in which the optical head is installed can leak into the entrance window. External dirt and dust may enter through the exit window, or people may enter through the exit window when loading a disc. Therefore, it may cause various troubles,
This caused a decrease in the reliability of the optical head.

This invention has been proposed in view of the above points, and an object of the present invention is to provide an optical head with a separation type that eliminates the influence of dirt and dust inside a disk drive device or dirt and dust caused by loading a disk. There is.

Means for Solving the Problems In order to achieve the above object, the present invention covers the laser beam entrance window of the actuator section and the laser beam exit window of the main body fixing section with a transparent plate through which the laser beam can pass. The transparent plate is made of a transparent material such as flat glass and/or plastic, and has an antireflection film formed on one or both sides thereof. In this case, it is also included in one configuration of the present invention to set the flatness of the transparent plate to be 174λ or less and the plate thickness to be 1 m/m or less, assuming that the wavelength of the laser beam used is human.

The present invention further provides a shielding plate that is slidably or rotatably supported in the laser beam entrance window of the actuator part and the laser beam exit window of the main body fixing part in the direction of opening and closing the window, and the shielding plate is optically supported. It is characterized by the provision of an opening means that opens in conjunction with the start of head operation.

According to one configuration of the present invention, the gist is that the laser beam entrance window of the actuator section and the laser beam exit window of the main body fixing section are connected by a bellows that is expandable and retractable in the movable direction of the actuator section. In this case, one aspect of the present invention includes applying surface treatment to the inner surface of the bellows to prevent diffused reflection.

The transparent plate covering the active laser input/output window allows laser light to pass through without any problem, but reliably prevents dirt and dust from entering.

In addition, the shield plate is closed when the disk drive device is not in use, and is opened when the optical head starts operating, so dirt and dust entering from the laser input/output window is drastically reduced to a minimum. .

Moreover, the passage of laser light through the entrance and exit windows can be carried out without any problem.

Furthermore, by connecting the entrance and exit windows with a telescopic bellows, the large exit window is completely shielded from the outside world, completely eliminating dirt and dust from entering.

The laser light emitted from the exit window passes through the inside of the bellows and is introduced into the entrance window. Therefore, the laser beam can pass through without any problem.

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows a first embodiment of the invention. The optical head according to the present invention is separated into a main body fixed part 10 and a movable actuator part 20.

The main body fixing part 10 is installed and fixed on a chassis base 100 of a disk drive device. Optical system components (not shown) including a semiconductor laser 111 are assembled into the optical base 110 of the main body fixing part 10. A laser beam exit window 120 is provided at a portion of the opto base 110 that faces the movable actuator section 20 . The laser beam emitted from the semiconductor laser 111 passes through the reflection mirror 11.
2, and travels straight through the exit window 120 in the direction of the actuator section 20.

On the other hand, the actuator section 20 is supported by a pair of parallel guide shafts 2L21 so as to be linearly reciprocated in the radial direction of the disk D.

An objective lens 22 is supported by the actuator section 20 so as to be movable in two-dimensional directions orthogonal to focusing and tracking. That is, the objective lens 22 is supported by the actuator section 20 and is controlled to move in the focusing direction and the tracking direction by its electromagnetic drive. In addition,
Since the electromagnetic drive system is well known, illustration thereof is omitted. A laser beam entrance window 2 is provided at a portion of the actuator section 20 that faces the exit window 120 formed in the main body fixing section 10.
3 have been established. The laser light emitted from the exit window 23 is
The light is introduced into the actuator section 20 through the entrance window 23 and is reflected vertically upward by the reflection mirror 24 disposed inside the actuator section 20 . Then, guided by the objective lens 22,
The lens 22 condenses the light and irradiates the disc surface as a spot. The reflected light is returned to the inside of the actuator unit 20 through the objective lens 22 again, travels straight from the entrance window 23 to the exit window 120 through the reverse path, and enters the main body fixing unit 10 through the exit window 120. be returned. Then, the light is received by a photodetector of a known signal detection optical system, and a focus and tracking control signal and a reproduction signal are read out. The actuator section 20 is sled-driven in the disk radial direction by a pair of left and right linear motors 25.25. The linear motor 25 is composed of a magnetic circuit 251 made up of a yoke body and a magnet installed on the chassis base 100, and a coil 252 built into the magnetic circuit 251. coil 252
is fixed to the lower part of one side of the actuator section 20, and is fitted onto the yoke body facing the magnet of the magnetic circuit with clearance.

In the above configuration, the laser beam exit window 120 of the main body fixing part 10 and the laser beam entrance window 23 of the actuator part 20 are
is covered and closed by a transparent plate 30 through which laser light can pass.

The transparent plate 30 is made of a transparent resin material such as flat glass or plastic, and has an antireflection film 30A on one or both sides thereof.
is formed. In the illustrated case, it is formed on one side. This antireflection film 30A significantly improves the utilization efficiency of the laser light that passes through the exit window 120 and the entrance window 23.

The flatness of the transparent plate 30 is 1/4λ or less, where λ is the wavelength of the laser beam used, and the plate thickness is preferably 1 m/
m or less. This prevents the diffraction phenomenon of laser light passing through the transparent plate 30.

According to this first embodiment, the laser beam exit windows 120 are formed in the main body fixing part 10 and the actuator part 20, respectively.
Since the entrance window 23 and the entrance window 23 are closed by the transparent plate 30, it is possible to completely prevent dirt and dust floating inside the drive device or from entering the optical system when the disc is loaded. It can be prevented. Moreover, since the transparent plate 30 is made of a material through which laser light can pass, the semiconductor laser 11 of the main body fixing part 10
The laser beam emitted from 1 can be guided into the actuator section 20 through the exit window 23 and the entrance window 23 without any trouble.

FIGS. 2 and 3 show a second embodiment of the separation type optical head according to the present invention, and the same parts as in FIG.

In this second embodiment, the exit window 1 of the main body fixing part 10
20 and the entrance window 23 of the actuator section 20 are each covered and closed by a shielding plate 40 that can be opened and closed.

The shielding plate 40 is formed of a transparent or opaque plate such as glass or plastic, or other metal plate material, rubber material, or the like. The most suitable one can be selected from among them.

As shown in detail in FIG. 3, the shielding plate 40 is supported so as to be slidable in the direction of opening and closing the input/output window 120.23, for example, in the horizontal direction in the figure. When the drive device is not in use, the shielding plate 40 slides in a direction to close the exit window 23.120, and when the drive device is in use, when the optical disk is rotated by the rotational drive of the spindle motor M, the shielding plate 40 is linked to the operation. and slide it to the other side to open the exit window 23.120. A slide mechanism 41 equipped with a drive source is provided between the main body fixing section 10 and the actuator section 20 . When the drive device starts operating, the slide mechanism 41 operates in response to a signal input from a system control built into the device, and slides the shielding plate 4
0 in the opening direction of the exit window 23.120. Thereby, the exit window 23.120 is opened only when the drive device is activated. Therefore, during operation of the drive device, the laser light emitted from the semiconductor laser 111 of the main body fixing section 10 is introduced into the actuator section 20 without any trouble through the exit window 120 and the entrance window 23, and is guided to the objective lens 22. Further, due to the return operation of the slide mechanism 41, the operation of the drive device is stopped and the shielding plate 40 is
slides back and both the person and the exit window 23 and 120 are permanently closed, so dirt and dust inside the device are removed from the person and the exit window 2.
3.It is possible to reliably prevent it from entering the interior through the 120.

Note that the shielding plate 40 may be supported by a rotating structure so as to be openable and closable, instead of a sliding structure.

FIG. 4 shows an example of this, in which the shielding plate 40' is formed into a substantially fan shape, and the main part of the fan shape rotates in the direction of opening and closing the input/output part 23.120. freely supported.

The shielding plate 40' is connected to a rotating mechanism 42 equipped with a drive source, and when the rotating mechanism 42 is operated in response to a signal from the system control to start the operation of the drive device, the shielding plate 40' is connected to a rotating mechanism 42 equipped with a driving source. 120 is rotated by a predetermined angle in one direction from the closed position to open the exit window 23.120. That is, the shield plate 40' rotates in one direction in conjunction with the start of operation of the drive device and the start of rotation of its spindle motor M, thereby opening the exit window 23.120.

In addition, the rotation mechanism 42 is connected to the stop of the drive device.
When the return operation is performed, the shield plate 40' is exposed to the person and the exit window 23.
Rotation returns to the closed position of 20.

Thereby, when the drive device is not in use, the exit window 23.120 is kept closed by the shielding plate 40'. Therefore, in this example as well, the effect of preventing dirt and dust from entering can be reliably achieved in the same way as above, and moreover, without interfering with the optical path of the laser beam,
The laser light emitted from the exit window 120 can be guided into the actuator section 20 through the entrance window 23 without any problem.

Next, FIGS. 5 and 6 show still other embodiments of the separation type optical head according to the present invention, and the same parts as in each of the above embodiments are denoted by the same reference numerals, and the explanation thereof will be omitted.

In this embodiment, the exit window 120 of the main body fixing part 10 and the entrance window 23 of the actuator part 20 are connected by a bellows 50. The bellows 50 is formed to be expandable and retractable in the movable direction of the actuator section 20, and the innermost diameter d2 when contracted is set to be larger than the beam diameter di of the laser beam, as shown in FIG. 6(b). has been done. One end of the bellows 50 is fixed to the wall surface of the main body fixing part at the periphery of the exit window 120. The other end is the entrance window 2
It is fixed to the wall surface of the actuator section around 3. The bellows 50 is installed coaxially with the optical axis of the laser beam passing through the centers of the exit window 120 and the entrance window 23, and the exit window 1
An optical path for laser light is formed that connects the entrance window 20 and the entrance window 23. As shown in FIG. 8(A), the inner surface of the bellows 50 is treated to prevent the irregular emission of laser light, for example, with a matte black coating, to prevent attenuation of the laser light due to diffuse reflection.

According to the structure of this embodiment, the laser beam emitter 23.
120 is always shielded from the outside world by the bellows 50, not only dirt and dust floating inside the drive device but also dirt and dust caused by loading the disk, people, and the ejection part 23
．． It is possible to completely and reliably prevent intrusion from 120, and moreover, the laser beam can pass through without any problem.

As described in detail, according to the present invention, in an actuator-separated optical head, the intrusion of dirt and dust into the main body fixed part and the movable actuator part is minimized and reduced. The influence on the optical system is drastically reduced. This reduces troubles during operation of the optical head and significantly improves its reliability.

[Brief explanation of the drawing]

FIG. 1 is a plan view of an actuator-separated optical head according to the present invention, FIG. 2 is a perspective view showing another embodiment of the optical head according to the present invention, FIG. 3 is a perspective view of the main part thereof, and FIG. 4 5 is a perspective view of a main part showing still another embodiment of the present invention, FIG. 5 is a plan view showing another embodiment of the invention, and FIGS. 6(a) and 6(b) are sectional views of the main part thereof. . 10◆ 20・23 fist40. 41 ・ 42Φ 50・ D@ Φ ・・Body fixing part, ・Exit window, ・・Actuator part, ・・Entrance window, 40” ・Fist/shielding plate, ・・Slide mechanism, ・Rotating mechanism, ・・Bellows・Optical disk.

Claims (1)

[Scope of Claims] (1) In an actuator-separated optical head in which an actuator part that supports an objective lens movably in orthogonal two-dimensional directions is separated from a main body fixing part, a laser beam entrance window of the actuator part; An actuator-separated optical head characterized in that the laser beam exit window of the main body fixing part is covered with a transparent plate through which laser beam can pass. (2) The actuator-separated optical system according to claim (1), wherein the transparent plate is made of a transparent material such as flat glass and/or plastic, and an antireflection film is formed on one or both sides of the transparent plate. head. (3) Claim (1) characterized in that, when the wavelength of the laser beam used is λ, the flatness of the transparent plate is set to 1/4λ or less, and the plate thickness is set to 1m/m or less. Actuator-separated optical head described in ). (4) In an actuator-separated optical head in which an actuator part that supports an objective lens movably in orthogonal two-dimensional directions is separated from a main body fixing part, a shielding plate is provided between the laser beam entrance window of the actuator part and the main body fixing part. An actuator characterized in that a laser beam emission window is provided with an opening means that is slidably or rotatably supported in the opening/closing direction of the window and that opens the shielding plate in conjunction with the start of operation of the optical head. Separate optical head. (5) In an actuator-separated optical head in which an actuator part that supports an objective lens movably in orthogonal two-dimensional directions is separated from a main body fixing part, a laser beam entrance window of the actuator part and a laser beam output of the main body fixing part are provided. An actuator-separated optical head characterized in that the actuator-separated optical head is connected to a window by a bellows that is extendable and retractable in the movable direction of the actuator. (6) The actuator-separated optical head according to claim (5), wherein the inner surface of the bellows is subjected to a surface treatment to prevent diffused reflection.