JP3453982B2 - Object lens drive mechanism for optical disk drive - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk device, and more particularly to an objective lens driving mechanism for an optical disk device, a magneto-optical disk device, etc., which uses a plurality of objective lenses selected by a lens switching mechanism.

[0002]

2. Description of the Related Art In a recording / reproducing system using an optical disc,
There are several different recording / playback methods. There is generally no compatibility between these systems, and users have dealt with this by preparing the necessary disks and disk devices as appropriate. In recent years, in order to support two or more types of recording / reproducing systems, an optical disc recording / reproducing device equipped with a plurality of optical systems has been proposed. For example, as shown in FIGS. 5, 6, and 7, an objective lens drive mechanism in which two objective lenses 1 and 2 are mounted on a lens holder 3 has been proposed. FIG. 4 is a plan view of a conventional two-lens type objective lens driving mechanism, and FIG. 5 is an operation state diagram of the two-lens type objective lens driving mechanism.

In FIG. 5, the objective lenses 1 and 2 are integrally held by a lens holder 3. The lens holder 3 is configured to be rotatable about the shaft member 4 and slidable in the axial direction. The coil 11 is mounted on the lens holder 3. A magnet 10 is mounted on the yoke 9,
A part of the coil 11 is present in the magnetic circuit formed by the yoke 9 and the magnet 10.
By passing a predetermined current through the coil 11, it is possible to rotate around the shaft member 4 and slide in the axial direction.

In FIG. 5 (a), the objective lens 1 is located at a position where information can be recorded / reproduced on the innermost peripheral portion of a disc (not shown). The lens holder 3 is rotatably held around the shaft member 4 in the arrow direction in the figure. York 9 and York 9
By passing a predetermined current through a coil 11 existing in a magnetic circuit constituted by a magnet 10 mounted on the lens holder 3, the lens holder 3 is finely driven around the shaft member 4, and a radial direction T (tracking) of a disk (not shown) is tracked. Direction). At a position where the objective lens drive mechanism can record and reproduce information on the innermost peripheral portion of the disc, the turntable 7 for placing the disc and the spindle motor 8 for rotationally driving the turntable 7 are located close to the objective lens drive mechanism. It is in. In FIG. 5B, the objective lens switching mechanism (not shown) rotates the lens holder 3 around the shaft member 4 in the direction of the arrow in the figure, and the objective lens 2 can record and reproduce information on the innermost peripheral portion of the disc (not shown). It shows the state of being positioned at various positions. Here, the objective lens 1 and the lens holder 3 are at positions overlapping the turntable 7, but are set so that there is a clearance in the height direction. As described above, the objective lens is switched to one of the states shown in FIGS. 5A and 5B depending on the disc to be recorded / reproduced.

In FIGS. 6 and 7, the disk 5 is a transparent substrate layer 5.
The recording / reproducing layer 5b is adhered on a, and the disc 6 has the recording / reproducing layer 6b adhered on the transparent substrate layer 6a. Here, the thickness of the transparent substrate layer 6a is smaller than the thickness of the transparent substrate layer 5a. Further, the objective lens 1 performs recording / reproducing on the recording / reproducing layer 5b of the disc 5, and the objective lens 2 performs recording / reproducing on the recording / reproducing layer 6b of the disc 6.
The disks 5 and 6 can be placed on the turntable 7. The lens holder 3 is integrated with the objective lenses 1 and 2 by applying a predetermined current to the coil 11 existing in the magnetic circuit formed by the yoke 9 and the magnet 10 mounted on the yoke 9, and the arrow in the figure Moves up and down in the F direction (focus direction). As a result, the objective lenses 1 and 2 focus the light beams from the light source (not shown) on the recording / reproducing layers 5b and 6b.

Next, the operation for recording / reproducing information on / from a disc having a different transparent substrate thickness will be described. Figure 6
(A) shows a case where recording / reproducing is performed on the innermost peripheral portion of the disc 6, and the objective lens 2 is used to focus the light beam on the recording / reproducing surface 6 b of the disc 6 mounted on the turntable 7. It shows the state. In order to write as much information as possible on the disc, a recording / reproducing area for information starts slightly outside the outer circumference of the turntable 7. Therefore, when the recording / reproducing operation is performed in the innermost peripheral portion of the disc 6, the unused objective lens 1 has to be submerged under the turntable 7 as shown in this figure. Further, FIG. 6B shows a case where recording / reproduction is performed on the innermost peripheral portion of the disc 5, and the objective lens 1 is used on the recording / reproducing surface 5b of the disc 5 mounted on the turntable 7 to collect the light beam. It shows the state of shining. By an objective lens switching mechanism (not shown), the objective lens 1 is moved and positioned to a position where information can be recorded and reproduced on the innermost peripheral portion of the disc 5, and the objective lens 1 is moved in the focus direction to form a recording and reproducing layer 5b. It condenses the light beam. At this time, since the objective lens 2 is retracted in the outer peripheral direction of the disc 5, it does not interfere with other members. Generally, in an optical disc device, the disc is identified by reproducing a recording signal recorded on the disc. That is, in order to identify the disc, it is necessary to read the information recorded on the disc mounted on the turntable using any objective lens. FIG. 7 (a) shows that when recording / reproducing is performed on the disc 5 having the transparent substrate layer 5a by using the objective lens 2 for recording / reproducing the disc 6, FIG. 7 (b) shows the thin transparent substrate layer 6a. 2 shows a state in which recording / reproduction is attempted to be performed on the disc 6 having the same by using the objective lens 1 for recording / reproduction of the disc 5. In this way, when the disc mounted on the turntable 7 and the objective lens are not a proper combination, the lens holder 3 is moved up and down in the focus direction shown by the arrow F in the figure, and the focusing operation is performed on the recording / reproducing layer. The objective lens will be moved up and down so that it can. At this time, if the transparent substrate layer is thin with respect to the objective lens as shown in FIG. 7B, the objective lens moves downward. On the contrary, if the transparent substrate layer is thicker than the objective lens as shown in FIG. 7A, the objective lens moves upward.

As described above, by rotating the corresponding objective lenses 1 and 2 on the lens holder around the shaft member 4 and selecting them appropriately, one optical disk device can support a plurality of recording / reproducing systems.

[0008]

In the objective lens driving mechanism for switching and using the two objective lenses on one lens holder as described above, the disk is formed on the thick transparent substrate layer 5a as shown in FIG. 7 (a). When the recording / reproducing objective lens 2 on the outer peripheral side is used, the objective lens 2 moves upward. Therefore, when recording / reproducing is performed at the innermost position of the disc, the objective lens 1 on the side closer to the rotation center of the disc that rises at the same time as the objective lens 2 may interfere with the turntable 7, and the objective lens drive mechanism. There was a problem that the range of movement in the focus direction could not be secured sufficiently.

[0009]

In order to solve such a problem, in the invention described in claim 1, a first optical disk having a substrate layer having a predetermined thickness and a thickness of the substrate layer of the first optical disk are used. An optical disk device for reproducing information from a second optical disk having a substrate layer having a thin thickness, for turning on a turntable for selectively mounting and rotating the optical disk and for reproducing information from the first optical disk. Holding the first objective lens and the second objective lens for reproducing information from the second optical disc, and two objective lenses are provided according to the type of the optical disc selectively placed on the turntable. A switchable lens holder, the lens holder is located below the turntable when the first objective lens is selected, and the second objective lens is connected to the first objective lens. Respect, held at a position close to the rotational center of the turntable.

According to the second aspect of the invention, in order to solve such a problem, a first optical disc having a substrate layer having a predetermined thickness and a substrate layer having a thickness different from the substrate layer of the first optical disc are provided. An optical disk device for reproducing information from a second optical disk, which has a turntable for mounting and rotating the optical disk, a first objective lens for reproducing information from the first optical disk, and a second A second objective lens for reproducing information from the optical disc, and the first objective lens and the second objective lens so that the second objective lens is closer to the rotation center of the turntable than the first objective lens. And a lens holder capable of selectively switching between the first objective lens and the second objective lens according to the type of the optical disc mounted on the turntable. In the optical disc device, which is positioned below the turntable when the lens is selected, the lens holder has a distance between the second objective lens and the optical disc mounted on the turntable that is equal to the first distance. The first objective lens and the second objective lens are arranged so as to be larger than the distance between the objective lens and the optical disc mounted on the turntable.
Hold the objective lens of.

In the present invention, the objective lens for focusing the light beam on the disk having the thin transparent substrate layer is arranged on the rotation center side of the disk mounted on the turntable. Therefore, when the objective lens is located below the turntable, the objective lens and the lens holder do not interfere with the lower surface of the turntable even if recording and reproducing are performed on a disc having transparent substrate layers having different thicknesses.

In another invention, the mounting height of the objective lens on the rotation center side of the disc mounted on the turntable is set to be lower. Therefore, the objective lens on the rotation center side does not interfere with the lower surface of the turntable regardless of the height variation of the objective lens on the outside.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings.

An embodiment of the objective lens driving mechanism of the optical disk device according to the present invention will be described with reference to FIGS. 1 to 3.
1 is a perspective view of a two-lens type objective lens driving mechanism in one embodiment of the present invention, FIG. 2 is a plan view of a two-lens type objective lens driving mechanism, and FIG. 3 is an operation of a two-lens type objective lens driving mechanism. It is a state diagram.

In FIG. 1, the objective lenses 1 and 2 are integrally held by a lens holder 3. The lens holder 3 is configured to be rotatable about the shaft member 4 and slidable in the axial direction. The coil 11 is mounted on the lens holder 3. A magnet 10 is mounted on the yoke 9,
A part of the coil 11 is present in the magnetic circuit formed by the yoke 9 and the magnet 10.
By passing a predetermined current through the coil 11, it is possible to rotate around the shaft member 4 and slide in the axial direction. The mirror 12 causes a light beam emitted from a light source (not shown) to enter the objective lens 1 or 2 positioned directly above the mirror 12.

The switching operation of the objective lenses 1 and 2 will be described with reference to FIG. In FIG. 2A, the objective lens 2 is at a position where information can be recorded / reproduced on the innermost peripheral portion of the disc (not shown). The lens holder 3 is rotatably held around the shaft member 4 in the arrow direction in the figure. By passing a predetermined current through a coil 11 existing in a magnetic circuit formed by the yoke 9 and a magnet 10 mounted on the yoke 9, the lens holder 3 is finely driven around the shaft member 4 to produce a disc (not shown). Can be positioned in the radial direction T (tracking direction). At a position where the objective lens drive mechanism can record and reproduce information on the innermost circumference of the disc, the turntable 7 on which the disc is placed and the spindle motor 8 which rotationally drives the turntable 7 are located at positions close to the objective lens drive mechanism. It is in. In FIG. 2B, an objective lens switching mechanism (not shown) rotates the lens holder 3 around the shaft member 4 in the direction of the arrow in the figure, and the objective lens 1 can record / reproduce information on / from the innermost peripheral portion of the disc (not shown). It shows the state of being positioned at various positions. Here, the objective lens 2 and the lens holder 3 are located at positions where they overlap the turntable 7, but are set so that there is a clearance in the height direction. As described above, the objective lens is switched to one of the states shown in FIGS. 2 (a) and 2 (b) according to the disc to be recorded / reproduced.

In FIGS. 3 and 4, the disk 5 is a transparent substrate layer 5
The recording / reproducing layer 5b is adhered on a, and the disc 6 has the recording / reproducing layer 6b adhered on the transparent substrate layer 6a. Here, the thickness of the transparent substrate layer 6a is smaller than the thickness of the transparent substrate layer 5a. Further, the objective lens 1 is for performing recording / reproducing on the recording / reproducing layer 5b of the disc 5,
The objective lens 2 performs recording and reproduction on the recording and reproduction layer 6b of the disc 6. The disks 5 and 6 can be placed on the turntable 7. The lens holder 3 is integrated with the objective lenses 1 and 2 by applying a predetermined current to the coil 11 existing in the magnetic circuit formed by the yoke 9 and the magnet 10 mounted on the yoke 9, and the arrow in the figure Moves up and down in the F direction (focus direction). As a result, the objective lenses 1 and 2 focus the light beams from the light source (not shown) on the recording / reproducing layers 5b and 6b.

Next, the operation of recording / reproducing information on / from a disc having a different transparent substrate thickness will be described. Figure 3
(A) shows a case where recording / reproducing is performed on the innermost peripheral portion of the disk 5, and the objective lens 1 is used to focus the light beam on the recording / reproducing surface 5b of the disk 5 mounted on the turntable 7. It shows the state. In order to write as much information as possible on the disc, a recording / reproducing area for information starts slightly outside the outer circumference of the turntable 7.
Therefore, when the recording / reproducing operation is performed in the innermost peripheral portion of the disk 5, the objective lens 2 which is not used as shown in FIG.
Has no choice but to sneak under the turntable 7. 3B shows a case where recording / reproduction is performed on the innermost peripheral portion of the disc 6, and a light beam is collected by using the objective lens 2 on the recording / reproducing surface 6b of the disc 6 mounted on the turntable 7. It shows the state of shining. By an objective lens switching mechanism (not shown), the objective lens 2 is moved and positioned to a position where information can be recorded and reproduced on the innermost peripheral portion of the disk 6, and the objective lens 2 is moved in the focus direction to form the recording and reproducing layer 6b. It condenses the light beam. At this time, since the objective lens 1 is retracted in the outer peripheral direction of the disc 6, it does not interfere with other members. Generally, in an optical disc device, the disc is identified by reproducing a recording signal recorded on the disc. That is, in order to identify the disc, it is necessary to read the information recorded on the disc mounted on the turntable using any objective lens. FIG. 4 (a) shows that when recording / reproducing is performed on the disc 6 having the thin transparent substrate layer 6a by using the objective lens 1 for recording / reproducing the disc 5, FIG. 4 (b) shows the thick transparent substrate layer. A state in which recording and reproduction are attempted to be performed on the disc 5 having 5a by using the objective lens 2 for reproducing the disc 6 is shown. In this way, when the disc mounted on the turntable 7 and the objective lens are not a proper combination, the lens holder 3 is moved up and down in the focus direction shown by the arrow F in the figure, and the focusing operation is performed on the recording / reproducing layer. The objective lens will be moved up and down so that it can. At this time, if the transparent substrate layer is thinner than the objective lens as shown in FIG. 4A, the objective lens moves downward. On the contrary, if the transparent substrate layer is thicker than the objective lens as shown in FIG. 4B, the objective lens moves upward. In the present invention, when the objective lens moves upward as shown in FIG. 4B, the objective lens 1 and the lens holder 3a do not exist below the turntable 7. Therefore, for discs having different transparent substrate layer thicknesses, sufficient clearance can be ensured even if the movable range of the objective lens driving mechanism is taken into consideration.

Another embodiment of the present invention will be described with reference to FIGS. 8 and 9. 8 and 9 show a configuration and an operation state diagram of a two-lens type objective lens driving mechanism. As shown in FIG. 8A, the objective lens 1 located closer to the center of rotation of the disc is held by the lens holder 3d at a position lower than the objective lens 2. As shown in FIG. 8B, when recording and reproducing on the disk 5 using the objective lens 1, the lens holder 3 is used by positioning it upward.
At this time, if the downward shift amount of the objective lens 1 is kept below the thickness of the turntable 7, the interference of the objective lens 2 positioned above the objective lens 1 with the lower surface of the disk 5 is surely avoided. It is possible to When the combination of the objective lens and the disc is different, the results are as shown in FIGS. 9 (a) and 9 (b). As shown in FIG. 9A, when recording / reproducing is performed by using the objective lens 2 for recording / reproducing on the disc 6, the objective lens 2 moves up to perform recording / reproducing on the disc 5 having the thick transparent substrate layer 5a. To do. Since the objective lens 1 below the turntable 7 is shifted downward, a sufficient clearance between the objective lens 1 and the turntable 7 can be secured. As shown in FIG. 9B, when the recording / reproducing is performed on the disc 6 having the thin transparent substrate layer 6a by using the recording / reproducing objective lens 1 of the disc 5, the objective lens 1 moves downward, which causes a problem. Absent. From the above,
A sufficient clearance between the objective lens drive mechanism and the turntable can be secured regardless of the arrangement of the two objective lenses.

In the present embodiment, the explanation has been made by using the shaft-sliding type objective lens driving mechanism in which the lens holder 3 is rotatable around the center of the shaft member 4, but the present invention is a driving system for the objective lens. However, other driving methods may be used. Further, the number of objective lenses is not limited to two.

[0021]

According to the present invention, in the objective lens driving mechanism which appropriately selects and uses two lenses, the objective lens for converging the light beam on the disk of the thin transparent substrate layer is provided on the rotation center side of the disk. It is configured to be placed. for that reason,
When the objective lens is located below the turntable,
Even if recording / reproducing is performed on a disc having transparent substrate layers having different thicknesses, a sufficient clearance can be secured without the objective lens and the lens holder interfering with the lower surface of the turntable.

According to a second aspect of the present invention, when the lens can be switched and the lens holder selects an objective lens located farther from the rotation center of the turntable, the lower part of the turntable is selected. The distance between the optical disk placed on the turntable and the objective lens located closer to the center of rotation of the turntable is greater than the distance between the optical disk placed on the turntable and the center of rotation of the turntable. The configuration is larger than the distance to the lens. Therefore, even when either of the two objective lenses is arranged closer to the rotation center of the turntable, a sufficient clearance can be secured between the objective lens and the lower surface of the turntable.

[Brief description of drawings]

FIG. 1 is a perspective view of a two-lens type objective lens driving mechanism according to an embodiment of the present invention.

FIG. 2 is a plan view of a two-lens type objective lens driving mechanism according to an embodiment of the present invention.

FIG. 3 is an explanatory diagram of an operating state of a two-lens type objective lens driving mechanism in one embodiment of the present invention.

FIG. 4 is an explanatory diagram of an operating state of a two-lens type objective lens driving mechanism in the embodiment of the present invention.

FIG. 5 is a plan view of a two-lens type objective lens driving mechanism in a conventional example.

FIG. 6 is an explanatory diagram of an operating state of a two-lens type objective lens driving mechanism in a conventional example.

FIG. 7 is an explanatory diagram of an operating state of a two-lens type objective lens driving mechanism in a conventional example.

FIG. 8 is an explanatory diagram of a configuration and an operating state of a two-lens type objective lens driving mechanism according to another embodiment of the present invention.

FIG. 9 is an explanatory diagram of a configuration and an operating state of a two-lens type objective lens driving mechanism according to another embodiment of the present invention.

[Explanation of symbols]

1, 2 ... Objective lens, 3a, 3b, 3c, 3d ... Lens holder, 4 ... Shaft member, 5a, 6a ... Transparent substrate layer, 5b, 6b ... Recording / reproducing layer, 7 ... turntable, 8 ... Spindle motor, 9 ... York, 10 ... Magnet, 11 ... coil, 12 ... Mirror, T ... tracking direction, F ... Focus direction.

Front page continuation (72) Inventor Maro Inui 1410 Inada, Hitachinaka City, Ibaraki Stock Company, Hitachi, Ltd. Personal Media Equipment Business Department (72) Inventor Yukio Fukui 292 Yoshida-cho, Totsuka-ku, Yokohama, Kanagawa (56) Reference JP-A-9-190638 (JP, A) JP-A-9-167351 (JP, A) JP-A-9-161289 (JP, A) JP-A-9 -138960 (JP, A) JP-A-9-115160 (JP, A) JP-A-9-81945 (JP, A) JP-A-9-35304 (JP, A) JP-A-8-329517 (JP, A) ) JP-A-6-333255 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G11B ^7/ 09-7/22 G11B 19/12

Claims (3)

(57) [Claims] 1. An optical disc apparatus for reproducing information from a first optical disc having a substrate layer having a predetermined thickness and a second optical disc having a substrate layer having a thickness smaller than that of the substrate layer of the first optical disc. A turntable on which the optical disc is mounted and rotationally driven; a first objective lens for reproducing information from the first optical disc; and a first objective lens for reproducing information from the second optical disc. A lens holder that holds two objective lenses and that can selectively switch the two objective lenses according to the type of the optical disc mounted on the turntable. The second objective lens is held at a position closer to the center of rotation of the turntable than the first objective lens, and the target objective lens is selected when the first objective lens is selected. An optical disk device characterized in that it is positioned below the table. 2. An optical disk device for reproducing information from a first optical disk having a substrate layer having a predetermined thickness and a second optical disk having a substrate layer having a thickness different from the substrate layer of the first optical disk. A turntable on which the optical disc is mounted and rotationally driven; a first objective lens for reproducing information from the first optical disc; and a second objective for reproducing information from the second optical disc. A lens, and the second objective lens holds the first objective lens and the second objective lens such that they are closer to the rotation center of the turntable than the first objective lens, A lens holder capable of selectively switching between the first objective lens and the second objective lens according to the type of the optical disc mounted on the table; The first objective lens and the optical disc mounted on the turntable are arranged such that the distance between the second objective lens and the optical disc mounted on the turntable is larger than the distance between the first objective lens and the optical disc mounted on the turntable. The optical disk device, which holds the objective lens and the second objective lens, and is located below the turntable when the first objective lens is selected. 3. The optical disk device according to claim 1, wherein the lens holder has a distance between the second objective lens and an optical disk mounted on the turntable that is equal to the first objective lens and the turn. An optical disc apparatus, wherein the first objective lens and the second objective lens are held so as to be larger than a distance from an optical disc placed on a table.