JPH08221779A - Objective lens driving device and optical head device - Google Patents

Abstract

PURPOSE: To stably perform recording/reproducing of optical information recording media having different sizes in substrate thickness with a simple constitution having a small number of parts by providing a plurality of objective lenses in positions equidistant from the axial center of a lens holder rotatable around its axial center and freely movable vertically in its axial direction. CONSTITUTION: A lens holder 6 rotating around a supporting shaft 103 and freely movable up and down in the vertical direction along the shaft 103 is provided with a plurality of objective lenses, for instance two groups, equidistant from the center of the shaft 103 at different heights. Lenses 3 and 4 are selectively used according to optical information recording/reproducing media formed by substrates having different sizes in thickness via the holder 6 and thus, without directly moving the lenses 3 and 4 in the direction of an optical axis, stable recording/reproducing of plural kinds of optical information recording/ reproducing media having substrates of different sizes in thickness with a small number of parts and with a simple constitution is performed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention records or reproduces a plurality of optical information recording media having different kinds of substrate thickness and recording sensitivity in one optical information recording / reproducing apparatus. The present invention relates to an objective lens driving device and an optical head device in which the light spots respectively focused on the information recording surface are most suitable for each medium and the track shift and the focus shift are accurately controlled. .

[0002]

2. Description of the Related Art FIG. 20 is a perspective view of a conventional objective lens driving device. In the figure, 2 is a light beam, which forms a light spot 201 by the objective lens 116. The objective lens 116 is attached to a lens holder 115 made of a lightweight and highly rigid plastic material, and the lens holder 115 has a bearing 118 such as an aluminum material. A balancer 117 is provided so as to face the objective lens 116. Further, the lens holder 115 has a focusing coil 119 and tracking coils 121 a, 1
21b is provided. The lens holder 115 is rotatably and vertically movable by the bearing 118 and the shaft 103 provided on the fixed side.
9 is arranged in the magnetic field formed by the focusing magnet 104 and the focusing yokes 105a and 105b provided on the fixed side. Also, the tracking coil 1
21a and 121b are two-pole magnetized magnets 1 provided on the fixed side.
It is arranged in the magnetic field formed by 07a and 107b (arranged at symmetrical positions (not shown)).

FIG. 21 is a diagram showing an optical system in a conventional optical head device. The light beam 2 emitted from the semiconductor laser passes through the diffraction grating 203 for the tracking sensor, the half prism 204, the collimator lens 205, and the reflection mirror 206 and enters the objective lens 116 to form a light spot 201. The light spot forms a light spot 201 on a medium (not shown), and the reflected light travels backward and passes through the focus sensor lens 207 by the half prism and is received by the photodetector 208. In the photodetector 208, the light spot 2 along with the information signal on the medium (not shown)
A focus shift and a track shift of 01 are detected, and feedback control is performed to the objective lens driving device according to these shift amounts.

FIG. 22 is a diagram showing the relationship between the optical information recording medium 202 and the objective lens 116 in the conventional optical head device. Although the light beam 2 incident on the objective lens 116 is condensed by the objective lens 116, the optical information recording medium is generally configured to pass through the layer of the plastic substrate 204 and read the information pit 203. Since the refractive index of the substrate 204 is different from that in air, if the substrate thickness is determined, it is necessary to provide a dedicated objective lens 116 corresponding thereto. In a well-known CD (compact disc), the substrate thickness (d1) is 1.2 mm. For example, in order to accommodate a medium having a substrate thickness of 0.6 mm, another objective lens specially designed is used. Need to use.

Also, the information pits 203 differ depending on the recording density. For example, a CD has a track pitch of about 1.6 μm
The pit width is about 0.5 μm, and the size of the light spot 201 to be read in this case is about 1.5 μm in diameter. In order to reduce the track pitch to about half (0.8 μm), the pit width also becomes small, so the light spot 20 to be read
The size of 1 also needs to be about 1 μm in diameter. For this purpose, it is necessary to change the numerical aperture or the like of the objective lens 116, and in this case as well, a dedicated objective lens is required.

For this reason, when recording or reproducing different types of optical information recording media with one device, an optical information recording / reproducing device equipped with a plurality of optical head devices having objective lenses having different specifications is used. Conceivable.

Reference numerals 311a and 311b are optical head devices having the above-mentioned objective lens driving device, and include objective lenses 301 and 302 having different specifications corresponding to optical information recording media having different substrate thicknesses and recording densities. It is equipped with. Reference numerals 312a and 312b denote the optical head device 3 described above.
Control coils for radial feed control provided on 11a and 311b, 313 are bases, 314a and 314b are radial direction control magnetic circuits fixedly provided on the base 313, and 315a and 315b are the optical heads. A shaft 316 fixedly provided on the base 313 and forming a movement axis of the devices 311a and 311b is a disc as an information recording medium.

Next, the operation will be described. When the optical information recording medium is set in the optical information recording / reproducing apparatus, an optical head device 3 equipped with an objective lens corresponding to the medium is set.
Recording or reproduction is performed by either 11a or 311b. For example, if an objective lens corresponding to the medium having a substrate thickness of 0.6 mm and 1.2 mm is provided, recording or reproduction suitable for each medium becomes possible. Further, in order to deal with media having different recording densities, if two types of objective lenses having different condensing characteristics (for example, numerical aperture) are provided, recording or reproduction suitable for each recording density can be performed.

By passing a desired current through the radial direction control coil of the selected optical head device, the optical head devices 311a and 311b are driven in the direction of arrow B to perform radial feeding.

In order to correct the focus shift of the light spot 201, a desired current is passed through the focusing coil 119, and an electromagnetic force obtained by the interaction with the magnetic field generated by the focusing magnet 104 causes the lens holder 115, As a result, the objective lens 116 is controlled in the direction of arrow C in the figure to control the focusing direction.
Further, when correcting the track deviation of the light spot 201, a desired current is applied to the tracking coils 121a and 121b, and the tracking magnet 107 is applied.
a, 107b (not shown, but arranged at symmetrical positions) is generated by interaction with the magnetic field, and the lens holder 115 is centered on the support shaft 103 in the direction of arrow D in the figure. Objective lens 1 rotated
16 tracking directions are controlled.

[0011]

Since the conventional apparatus is constructed as described above, it is equipped with an objective lens corresponding to the difference in recording density or substrate thickness of the optical information recording medium for reproducing or recording. There is a problem that a plurality of optical head devices and their radial feed mechanisms are required, the number of parts of the device is increased, and the cost is significantly increased.

There is also a problem that the device is large and has a complicated structure.

The present invention has been made in order to solve the above-mentioned problems, and allows a plurality of objective lenses to be selectively arranged in the same beam, has a simple construction, has a small number of parts, and is inexpensive. An objective lens driving device and an optical head capable of realizing an optical information recording / reproducing device which is small and can record and reproduce optical information recording media having different substrate thicknesses and recording densities with one optical head device. The purpose is to obtain the device.

[0014]

SUMMARY OF THE INVENTION An objective lens driving device according to claim 1 of the present invention includes a lens holder which is rotatable about one axis and vertically movable along the axis, and the lens holder. A plurality of objective lenses provided at positions decentered from the axis by a substantially equal distance, and the lens holder is moved up and down along the axis and rotated around the axis to form a light spot on the optical information recording medium. Differences in the substrate thickness and recording density of the optical information recording medium are provided with a driving device that drives in the focal direction and in the direction traversing the track, and means for determining the difference in the substrate thickness and recording density of the optical information recording medium. According to the above, the objective lens is selectively moved into the same light beam to form an optimum light spot on each medium to record or reproduce information.

In the objective lens driving device according to the second aspect of the present invention, a step is provided on the mounting surface of the plurality of objective lenses provided on the lens holder.

In the objective lens driving device according to a third aspect of the present invention, the means for selecting the objective lens and moving the objective lens in the light beam are the same as the means for rotating the lens holder around the axis. This is performed by using a driving device.

According to a fourth aspect of the present invention, there is provided an objective lens driving device, which restores a midpoint of the same number as or more than the number of the objective lenses so as to generate a midpoint restoring force for each of the plurality of objective lenses. A force generating means is provided.

An objective lens driving device according to a fifth aspect of the present invention is provided with means for selecting the objective lens and limiting the range of movement of the objective lens.

An objective lens driving device according to a sixth aspect of the present invention comprises means for detecting which one of the plurality of objective lenses is selected.

An objective lens driving device according to a seventh aspect of the present invention comprises means for detecting the rotational position of the lens holder.

In the objective lens driving device according to the eighth aspect of the present invention, the driving means for driving the lens holder in the direction traversing the track is provided in the same number as or more than the number of the holding objective lenses.

An objective lens driving device according to claim 9 of the present invention comprises at least means for selecting the objective lens and moving the objective lens in a light beam, and means for rotating the lens holder about a spindle. It is designed to be used partially.

According to a tenth aspect of the present invention, there is provided an objective lens driving device, wherein the plurality of objective lenses are provided at positions substantially symmetrical with respect to the support shaft on the lens holder.

An objective lens driving device according to an eleventh aspect of the present invention is a lens holder rotatably and slidably supported by a support shaft, and a position eccentric to the lens holder substantially symmetrically with respect to the support shaft. A plurality of objective lenses provided in, and a drive device for sliding and rotating the lens holder with respect to a support shaft to drive a light spot on the optical information recording medium in a focal direction and a direction crossing a track. The optical information recording medium is provided with a means for determining a difference in substrate thickness, recording density, etc.,
The objective lens is selected according to the difference in the substrate thickness and the recording density of the optical information recording medium, and a light beam is incident thereon to form a light spot for recording and reproducing information.

According to a twelfth aspect of the present invention, in the objective lens driving device, an elastic member movable in the up and down direction of an axis line substantially orthogonal to the surface of the optical information recording medium, and an axis line provided on the elastic member as a fulcrum. A rotatably supported lens holder, a plurality of objective lenses provided on the lens holder at positions eccentric from the axis by a substantially equal distance, and moving the lens holder vertically with respect to the axis. A driving device that drives an optical spot on an optical information recording medium by rotating about an axis as a fulcrum in a focal direction and a direction crossing a track, and a means for discriminating a difference in substrate thickness or recording density of the optical information recording medium. The objective lens is selected according to the difference in the substrate thickness or recording density of the optical information recording medium and moved into the light beam to form a light spot to record / reproduce information. It is intended.

In the optical head device according to the thirteenth aspect of the present invention, the lens holder provided with a plurality of objective lenses is moved with respect to one light beam emitted from the light source, so that the objective beam is included in the light beam flux. By selectively arranging the lenses, an objective lens suitable for the optical information recording medium is selected, an optimum light spot is formed, and the lens holder is driven to defocus and track the light spot. Is to be corrected.

[0027]

In the objective lens driving device according to the present invention,
The objective lens is selected according to the difference in the substrate thickness or recording density of the optical information recording medium and moved into the light beam to form a light spot to record / reproduce information.

In the objective lens driving device according to the present invention, the positional relationship between the optical information recording medium and the lens holder can be set to be the same regardless of the selected objective lens.

Further, in the objective lens driving device according to the present invention, the means for selecting the objective lens and moving the objective lens in the light flux are the same as the means for rotating the lens holder about the support shaft. It is performed by using a driving device.

Further, in the objective lens driving device according to the present invention, the midpoint restoring force is generated for each of the plurality of objective lenses.

Further, in the objective lens driving device according to the present invention, the range of moving the objective lens is limited by selecting the objective lens.

Further, in the objective lens driving device according to the present invention, it is detected which one of the plurality of objective lenses is selected.

Further, in the objective lens driving device according to the present invention, the rotational position of the lens holder is detected.

Further, in the objective lens driving device according to the present invention, each of the plurality of objective lenses is driven by its own driving means.

Further, in the objective lens driving device according to the present invention, at least one of means for selecting the objective lens and moving the objective lens in the light flux, and means for rotating the lens holder with respect to the support shaft. Also serves as a division.

Further, in the objective lens driving device according to the present invention, the plurality of objective lenses are provided at positions substantially symmetrical with respect to the axis on the lens holder, and the substrate thickness of the optical information recording medium and recording are performed. An objective lens is selected according to a difference in density and the like, and the objective lens is moved into a light beam to form a light spot to record and reproduce information.

Further, in the objective lens driving device according to the present invention, the objective lens is selected according to the difference in the substrate thickness and recording density of the optical information recording medium and the luminous flux is made incident on the objective lens driving device.
Information is recorded and reproduced by forming a light spot.

Further, in the objective lens driving device according to the present invention, an elastic member movable in the up and down direction of an axis line substantially orthogonal to the surface of the optical information recording medium, and a rotary member provided on the elastic member and having the axis line as a fulcrum. Equipped with a movably supported lens holder, the objective lens is selected according to the difference in the substrate thickness or recording density of the optical information recording medium and moved into the light beam,
Information is recorded and reproduced by forming a light spot.

In the optical head device according to the present invention, different types of objective lenses corresponding to different types of optical information recording media are prepared in advance and suitable for the inserted optical information recording medium. The objective lens is selected.

[0040]

【Example】

Example 1. 1 is a perspective view showing an objective lens driving device in a first embodiment of the present invention, FIG. 2 is an exploded perspective view showing an objective lens driving device in a first embodiment of the present invention, and FIG. 3 is an objective in the first embodiment of the present invention. It is a top view which shows a lens drive device. FIG. 4 is a diagram showing a positional relationship among the objective lens, the lens holder, and the optical information recording medium in the objective lens driving device according to the first embodiment of the present invention. FIG. 5 is a diagram showing the relationship between the rotation angle of the lens holder and the restoring force generated in the tracking direction in the objective lens driving device according to the first embodiment of the present invention. In the figure, the same or corresponding parts as those in FIGS. 20 to 23 are designated by the same reference numerals.

In FIGS. 1 to 4, reference numeral 1 denotes a fixed base made of a magnetic material, which has screw portions 1b and 1c near the bottom surface of the rear surface and the side surface. In addition, a protrusion and a through hole 1d are provided in the vicinity of the bottom surface of the side surface in the direction substantially opposite to the sum of the vector going from the support shaft to 1b and the vector going to 1c. A spherical surface 1e having a center at a point on the optical axis is provided on the bottom surface of the fixed base 1. Reference numeral 2 is a light beam formed by the objective lens 3 or 4.

Reference numeral 5 denotes a support shaft holding base, which holds the lower end of the support shaft 103 coated with a fluororesin having a small friction coefficient. Reference numerals 104a and 104b denote focusing magnets that are vertically magnetized, and are bonded and fixed to the spindle holding base 5 together with the focusing yokes 105a and 105b.
Are adhesively fixed to the fixed base 1.

Reference numerals 107a and 107b are tracking magnets which are bipolarly magnetized in the left-right direction and are fixed to the fixed base 1 by adhesion. Reference numeral 108 is a launching mirror that reflects the light beam 2 incident from the front vertically upward.
Reference numeral 109 denotes a relay substrate for applying a drive current, which is fixed to the fixed base 1 by adhesion.

Reference numeral 6 denotes a lens holder formed of a lightweight and highly rigid plastic material or the like, which supports objective lenses 3 and 4 corresponding to a plurality of different optical information recording media having different substrate thicknesses and recording densities. It is held at a position eccentric from the shaft 103 by a substantially equal distance. The lens holder 6 is integrally provided with a bearing portion having an axis substantially parallel to the optical axes of the objective lenses 3 and 4. Also, the objective lens 3
The lens holders 6 and 4 and the lens holder 6 are configured to have a dynamic balance in the rotation direction.

As shown in FIG. 4, generally, the objective lenses 3 and 4 corresponding to different substrate thicknesses or recording densities are placed at positions where the light spot 201 or 201 'is focused on the optical information recording medium. At this time, the distances (called working distances) W1 and W2 from the lower surface of the medium are different. The lens holder 6 is configured such that each objective lens mounting surface is stepped by the difference between W1 and W2. As a result, even when the medium is changed, the operating position in the vertical movement direction can be made substantially the same.

Reference numeral 119 denotes a focusing coil fixed to the lens holder 6 so as to be coaxial with the bearing portion, and has a magnetic gap formed by the support shaft holding base 5 and the focusing yokes 105a and 105b. It is configured to be placed inside. Reference numeral 7 denotes a movable part relay substrate fixed to the lens holder 6, which connects between the tracking coils 121a and 121b adhered and fixed to both side surfaces of the lens holder 6, and the focusing coil 119 and the tracking coil 121a. , 121b has a function of a relay board for supplying a drive current through the lead wires 8a to 8d.

Reference numerals 124a and 124b denote magnetic pieces, which are tracking magnets 107a and 1a of the lens holder.
It is adhesively fixed to the portion facing 07b.

Reference numeral 11 denotes a special screw having a cylindrical portion having a diameter larger than that of the screw portion, 12 is a spring, 13 and 14 are screws, and 15 is an eccentric pin.

Next, the operation will be described. When the optical information recording medium is set in the optical information recording / reproducing apparatus, the difference in the substrate thickness and the recording density of the medium is discriminated, and the objective lens corresponding to the difference in the medium thickness and the recording density (in FIG. Select 4). For example, an objective lens corresponding to a substrate thickness of 0.6 mm and 1.2 mm is provided, or an objective lens having a numerical aperture of 0.6 and 0.4 is provided, and either one is selected. Here, the selected objective lens is the light beam 2
If it exists, the focus pull-in operation is started. On the other hand, if the selected objective lens is not present in the light beam 2, the tracking coils 121a, 1
21b, a desired current is applied, and the lens holder 6 is rotated about the support shaft 103 by an electromagnetic force obtained by the interaction with the magnetic fields generated by the tracking magnets 107a and 107b, and the corresponding objective lens is changed to a light beam. Move into 2 After that, the focus pull-in operation is started.

To correct the focus shift of the light spot 201 or 201 ', a desired current is applied to the focusing coil 119 and an electromagnetic force obtained by the interaction with the magnetic field generated by the focusing magnets 104a and 104b. The movable part, and thus the objective lens 3
Alternatively, 4 is controlled in a direction perpendicular to the optical information recording medium to control the focusing direction. Further, when correcting the track shift of the light spot 201 or 201 ′, a desired current is applied to the tracking coils 121 a and 121 b, and the tracking magnet 1 is applied.
By the electromagnetic force obtained by the interaction with the magnetic field generated by 07a and 107b, the movable portion is rotated about the support shaft 103 in the direction traversing the track of the optical information recording medium by the electromagnetic force, and the objective lens 3 or 4 is rotated. Control the tracking direction of.

The magnetic pieces 124a and 124b are used for the tracking magnet 10 when the lens holder 6 is at the center position.
It is arranged at a point where the magnetic flux density is highest in the magnetic field generated by 7a and 107b. As the lens holder 6 moves in both the focusing direction and the tracking direction, the magnetic flux density changes, which causes magnetic restoring force. The rotation angles D1 and D2 are shown in FIG.
The magnetic piece 12 is provided so that linear characteristics can be obtained within a range of about (D1 + D2 + movement angle for tracking deviation correction).
The shapes of 4a and 124b are determined. The movement angle for tracking error correction is about 10 degrees in a general configuration.

Although a rubber damper may be used as the means for obtaining the restoring force as shown in the conventional embodiment, it is preferable to use the magnetic piece as described above because the linear range in the tracking direction can be widened.

The fixed base 1 has a special screw 11 and a spring 12.
Is pressed so as to contact the head base (not shown) at the spherical portion of the lower surface. By adjusting the tightening amount of the screw 13 from below the head base, the fixed base 1, and thus the objective lenses 3 and 4 in the track direction of the optical information recording medium are centered around the center of the spherical portion, that is, the point on the optical axis. The tilt of the optical axis can be adjusted. Similarly, by adjusting the tightening amount of the screw 14, it is possible to adjust the inclination of the optical axis of the fixed base 1, and thus the objective lenses 3 and 4, in the direction perpendicular to the track of the optical information recording medium.

Although omitted in this description, an optical system similar to the optical system portion of the conventional example shown in FIG. 21 is also used in this embodiment.

Example 2. 6 is an exploded perspective view showing an objective lens driving device according to a second embodiment of the present invention, and FIG. 7 is a plan view showing an objective lens driving device according to a second embodiment of the present invention.
FIG. 8 is a diagram showing the relationship between the rotation angle of the lens holder and the restoring force generated in the tracking direction in the objective lens driving device according to the second embodiment of the present invention. In the figure,
5, the same or corresponding parts as in FIGS. 20 to 23 are designated by the same reference numerals.

Reference numerals 11a, 11b, 11c and 11d denote magnetic pieces, which are fixed to a plurality of lens holders in the polarization direction of the tracking magnet.

Next, the operation will be described. The means for detecting the difference in the thickness or recording density of the optical information recording medium (not shown) detects the difference between the media, and the corresponding objective lens (objective lens 4 in FIG. 7) is selected. Then, the objective lens 4 is moved to the light beam 2 by the means shown in the first embodiment.
Placed inside. When the objective lens 4 is located substantially in the center of the light beam, the magnetic pieces 11b and 11c are located substantially in the center of the tracking magnets 107a and 107b (at the point of the maximum magnetic flux density), and the magnetic pieces 11a and 1b are located.
1d is arranged at a position where the magnetic field of the tracking magnet is almost nonexistent. When the optical information recording mediums having different substrate thicknesses and recording densities are set, the objective lens 3 is selected, and when the objective lens 3 is located at the substantially center of the light beam 2, the magnetic pieces 11a and 11d cause the tracking magnets 107a to move. , 107b, and the magnetic pieces 11b, 11c are arranged at positions where the magnetic field of the tracking magnet is scarcely present. Therefore, the relationship between the rotation angle of the lens holder and the restoring force is as shown in FIG. The other operation is the first embodiment of the present invention.
Is the same as

Example 3. FIG. 9 is a plan view showing an objective lens driving device in Embodiment 3 of the present invention. In the figure, parts that are the same as or correspond to those in FIGS. 1 to 8 and 20 to 23 are assigned the same reference numerals.

Reference numerals 21a and 21b denote fins protruding from the lens holder 6, and 22 denotes a wall portion provided on the fixed base 1.

Next, the operation will be described. When the optical information recording medium is set in the optical information recording / reproducing apparatus, the difference in the substrate thickness and the recording density of the medium is discriminated by means not shown, and the objective lens corresponding to the type of the medium is selected. When the selected objective lens does not exist in the light beam 2, the lens holder 6 is rotated around the support shaft 103 by the electromagnetic force, and the corresponding objective lens is moved into the light beam 2. At that time, if the objective lens tries to rotate more than necessary, the fins 21a provided on the lens holder 6
(The fin 21b when rotating in the opposite direction) is the wall 22
It contacts with and limits the further rotation. Other operations are similar to those of the first or second embodiment of the present invention.

Example 4. 10 and 11 are plan views showing an objective lens driving device according to the fourth embodiment of the present invention.
In the figure, the same or corresponding parts as those in FIGS. 1 to 9 and 20 to 23 are designated by the same reference numerals.

Reference numeral 31 is a fin projecting from the bottom of the lens holder 6, and 32 is a position detecting sensor provided on the fixed base 1 so as to be located under the lens holder 6.

Next, the operation will be described. When the optical information recording medium is set in the optical information recording / reproducing apparatus, the difference in the substrate thickness and the recording density of the medium is discriminated by means (not shown), and the objective lens corresponding to each medium is selected.
When the selected objective lens does not exist in the light beam 2, the lens holder 6 is rotated around the support shaft 103 by the electromagnetic force, and the corresponding objective lens is moved into the light beam 2. When the objective lens 3 is selected, the fin 31
Is located in the position detection sensor 32. On the other hand, when the objective lens 4 is selected, the fin 31 moves to the position detection sensor 32.
Located outside of. Therefore, it is possible to detect which objective lens is currently selected from the output of the position detection sensor 32. The other operation is the first embodiment of the present invention.
Alternatively, it is similar to the second and third embodiments.

Example 5. FIG. 12 is a plan view showing an objective lens driving device in Embodiment 5 of the present invention. In the figure, parts that are the same as or correspond to those in FIGS. 1 to 11 and 20 to 23 are assigned the same reference numerals.

41 is a fin protruding from the bottom of the lens holder 6, 42 and 43 are located under the lens holder 6,
A light source and a two-divided photodetector provided on the fixed base 1 so as to sandwich the fin 42.

Next, the operation will be described. When the lens holder 6 rotates around the support shaft 103, the fin portion 41 of the lens holder 6 moves, and the photodetector 43 according to the movement amount.
The amount of light incident on each portion of the optical information recording medium divided in the direction perpendicular to the track changes. The rotational position of the lens holder 6 can be obtained based on the signal output of the two-divided photodetector 43. Based on this information, it is possible to detect which objective lens is currently selected. The other operations are similar to those of the first embodiment or the second and third embodiments of the present invention.

Furthermore, it is also possible to electrically apply a restoring force to the objective lens based on the signal output of the two-divided photodetector 43.

Example 6. FIG. 13 is a plan view of the objective lens driving device according to the sixth embodiment of the present invention. In the figure,
The same or corresponding parts as in FIGS. 1 to 12 and 20 to 23 are designated by the same reference numerals.

51a, 51b, 51c and 51d are tracking coils fixed to the lens holder 6, 52a,
Reference numerals 52b, 52c, and 52d denote magnetic pieces fixed to the lens holder 6 so as to overlap with the tracking coil.

Next, the operation will be described. When the optical information recording medium is set in the optical information recording / reproducing apparatus, the difference in the substrate thickness and the recording density of the medium is discriminated by means (not shown), and the objective lens corresponding to each medium thickness is selected. . The tracking coils 51a and 51d are used for the tracking magnet 107 when the objective lens 3 is selected.
It is arranged at a position facing a and 107b.
Therefore, at this time, the tracking coils 51a, 5
The lens holder is rotated by the electromagnetic interaction between 1d and the tracking magnets 107a and 107b. Further, when the objective lens 4 is selected, the tracking coils 51b and 51c are arranged at positions facing the tracking magnets 107a and 107b, and the tracking coils 51b and 51c and the tracking magnets 107a and 107b are electrically connected to each other. The action causes the lens holder to rotate.

When the objective lens 3 is selected, the magnetic piece 5
When the objective lens 4 is selected by 2a and 52d, the magnetic pieces 52b and 52c give a restoring force to the lens holder. Other operations are similar to those of the first or second embodiment of the present invention.

During the control operation, all of the tracking coils 51a, 51b, 51c and 51d may be energized, or the energized coils may be selectively switched.

Example 7. FIG. 14 is a plan view showing an objective lens driving device in Embodiment 7 of the present invention. In the figure, parts that are the same as or correspond to those in FIGS. 1 to 13 and 20 to 23 are assigned the same reference numerals.

Reference numeral 61 denotes a two-pole magnetized magnet provided on the fixed base 1.

Next, the operation will be described. When the optical information recording medium is set in the optical information recording / reproducing apparatus, the difference in the substrate thickness and recording density of the medium is discriminated by means not shown, and the objective lens corresponding to each medium is selected. When the selected objective lens does not exist in the light beam 2, the lens holder 6 is rotated around the support shaft 103 by the electromagnetic force, and the corresponding objective lens is moved into the light beam 2. At that time, the tracking magnet 10
In addition to the tracking coil facing 7a and 107b, the tracking coil facing the magnet 61 is also energized to generate a driving force. Other operations are similar to those of the sixth embodiment of the present invention.

Example 8. FIG. 15 is a perspective view showing an objective lens driving device according to Embodiment 8 of the present invention, and FIG. 16 is an exploded perspective view of the objective lens driving device according to Embodiment 8 of the present invention. In the figure, parts that are the same as or correspond to those in FIGS. 1 to 14 and 20 to 23 are assigned the same reference numerals.

Reference numeral 71 denotes a lens holder made of a lightweight and highly rigid plastic material or the like, which holds a plurality of objective lenses at positions substantially symmetrical with respect to the support shaft 103. The lens holder 71 is provided with a bearing portion having an axis substantially parallel to the optical axes of the objective lenses 3 and 4.

Reference numeral 72 denotes a multi-pole magnetized magnet fixed to the lens holder 71 so as to be coaxial with the bearing portion.

Reference numeral 73 denotes a focusing coil fixed to the support shaft holding base 5, which includes the magnet 72 and the support shaft holding base 5.
Is arranged in a magnetic circuit consisting of. 74a, 74b
Is a tracking coil fixed on the fixed base 1, and is arranged in the magnetic circuit including the magnet 72 and the fixed base 1.

Next, the operation will be described. In the first embodiment of the present invention, the magnet is provided on the fixed side and the coil on the movable side is energized to perform movement of the objective lens corresponding to each medium, focusing control, and tracking control. The eighth embodiment has a structure in which a coil is arranged on the fixed side and a magnet is arranged on the movable side. In the case of being compatible with different optical information recording media, the lens holder 71 is used.
Rotate 180 ° to replace objective lenses 3 and 4.
Other operations are the same.

Example 9. FIG. 17 is a perspective view showing an objective lens driving device in Embodiment 9 of the present invention. In the figure, the same or corresponding parts as those in FIGS. 1 to 16 and 20 to 23 are designated by the same reference numerals.

Reference numeral 81 is a reflecting mirror which reflects the light beam 2 in a direction substantially parallel to the surface of the optical information recording medium, and is arranged so as to be rotatable in the arrow T direction by a driving means (not shown). Reference numeral 82 is a reflection mirror that reflects the light beam 2 in a direction substantially parallel to the surface of the optical information recording medium, and reference numerals 83 and 84 are launch mirrors that launch the light beam 2 vertically upward.

Next, the operation will be described. When the optical information recording medium is set in the optical information recording / reproducing apparatus, the difference in the substrate thickness and recording density of the medium is discriminated by means not shown, and the objective lens corresponding to each medium is selected. When the objective lens 3 is selected, the light beam 2 is reflected by the reflection mirror 81, is further launched vertically upward by the launch mirror 83, is incident on the objective lens 3, and forms a light spot on the optical information recording medium. . The subsequent operation is similar to that of the eighth embodiment.

On the other hand, when the objective lens 4 is selected,
Since the reflecting mirror 81 is rotated in the direction of arrow T by the driving means (not shown) and retracts from the light beam, the light beam 2 goes straight on. Then, the light beam 2 is reflected by the reflection mirror 82, further launched vertically upward by the launching mirror 84, and enters the objective lens 4, forming a light spot on the optical information recording medium. The subsequent operation is similar to that of the eighth embodiment.

If the reflecting mirror 81 is a half prism (for example, 50% of reflected light and 50% of transmitted light), it can be realized without rotating and the same effect can be obtained.

Example 10. 18 shows a tenth embodiment of the present invention.
3 is a perspective view showing the objective lens driving device in FIG. In the figure, parts that are the same as or correspond to those in FIGS. 1 to 17 and 20 to 23 are assigned the same reference numerals.

Reference numeral 1f denotes a spring support base provided on the fixed base 1, and 91a and 91b have one ends fixed to the spring support base 1f and extend so as to be substantially parallel to the optical information recording medium surface. The leaf springs, 92 are the leaf springs 91a, 9
It is a pivot bearing which is provided on 1b and rotatably supports the lens holder 6.

Next, the operation will be described. Leaf spring 91
Since a and 91b are configured as described above, when a desired current is applied to the focusing coil 119, the focusing coil 119 is moved by electromagnetic force in the vertical direction substantially parallel to the optical axis of the objective lens to perform focusing control. On the other hand, when a desired current is applied to the tracking coils 121a and 121b, the tracking coils 121a and 121b are rotated about the pivot bearing by an electromagnetic force, and the tracking control and the corresponding objective lens are moved into the light beam. Other operations are the same as those in the first embodiment.

In the above embodiment, the spring support is provided on the fixed base 1 and the pivot bearing is provided on the leaf spring thereof. However, the pivot bearing is provided on the fixed base 1 and can be rotated about the pivot bearing. It is needless to say that the same effect can be obtained even if a flat spring is extended and a plurality of objective lenses are provided in the vicinity of the tip of the flat spring at substantially equal distances from the pivot bearing.

Example 11. FIG. 19 shows an eleventh embodiment of the present invention.
2 is an exploded perspective view showing the objective lens driving device in FIG.
In the figure, parts that are the same as or correspond to those in FIGS. 1 to 17 and 20 to 23 are assigned the same reference numerals.

151a and 151b are magnets and 152a and 1a.
52b is a yoke 153a, 153b, 153c, 153
d is a rubber damper, 154a, 154b (not shown), 1
54c (not shown) and 154d (not shown) each have 15
Wires provided in rubber dampers 3a to 153d, 1
Reference numeral 55 is a support plate, and 156a and 156b are objective lens holders.

Next, the operation will be described. Rubber damper 1
53a to 153d and the tracking coils 121a to 121d and the focusing coil 119 provided on the holders 156a and 156b held by the wires 154a to 154d, respectively, are energized with a desired current, thereby deviating the track and defocus of the objective lenses 3 and 4. Can be corrected.
Similar effects can be obtained by selecting the objective lenses 3 and 4 according to the type of the optical information recording medium as in the other embodiments.

[0093]

As described above, according to the objective lens driving device of the present invention, the lens holder 6 which is rotated around the axis and is vertically movable along the axis is provided on the lens holder 6. A plurality of objective lenses provided at positions eccentric from the axis by a substantially equal distance are provided, and the objective lens is selected according to the difference in the substrate thickness and recording density of the optical information recording medium to move into the light beam, and Since a spot is formed to record and reproduce information, it has a simple structure with a small number of parts, is inexpensive and compact, and is the most suitable optical information recording medium with different substrate thickness and recording density. An optical information recording / reproducing apparatus capable of recording or reproducing under the conditions can be realized. In particular, according to this example in which the method of defining the movement direction of the lens holder 6 and the method of defining the movement center can be separated, it is possible to switch the objective lenses 3 and 4 without any difficulty. Further, since the dynamic balance in the turning direction is maintained, stable movement can be realized without any movement in the vertical movement and the turning direction regardless of which objective lens is selected.

According to the objective lens driving apparatus of the present invention, even if a plurality of objective lenses held by the lens holder and having different specifications are selected and used, the positional relationship between the optical information recording medium and the lens holder is selected. Is constant, the amount of movement in the focusing direction can be constant, the operation is stable, and the objective lens driving device can be downsized and simplified.

According to the objective lens driving device of the present invention, the means for selecting the objective lens and moving the objective lens in the light flux and the means for rotating the lens holder about the support shaft are driven by the same drive. Since it can be performed by using the apparatus, it is possible to obtain an inexpensive objective lens driving apparatus having a small number of parts.

According to the objective lens driving device of the present invention, since the center point restoring force is generated for each of the plurality of objective lenses, the operation center position of each objective lens can be easily defined. At the same time, stable and highly reliable control operation for each objective lens becomes possible. Further, since the reaction force generated when the objective lens is selected and moved can be reduced, a compact and inexpensive objective lens driving device can be obtained.

According to the objective lens driving device of the present invention, the range in which the objective lens moves is limited, so that when the objective lens is selected and moved, it does not move too much, and quick positioning is performed. You can

According to the objective lens driving device of the present invention, which objective lens is selected from the plurality of objective lenses is selected, so that the objective lens can be selected quickly and accurately.

According to the objective lens driving device of the present invention, since the rotational position of the lens holder is detected, it is possible to determine which objective lens is selected from the plurality of objective lenses, and to quickly select the objective lens. Can be done. Further, since the restoring force can be generated electrically in the lens holder, the number of parts can be reduced, and stable control operation can be performed without mechanical restriction in the operation range.

According to the objective lens driving device of the present invention, the driving means for driving the lens holder in the direction traversing the track is provided in the same number as or more than the number of the objective lenses to hold the driving means, and the driving force is efficiently provided. Therefore, the power consumption of the device can be reduced. Further, it is possible to easily cope with a high rotation speed of the optical information recording medium.
Further, since the center point restoring force is generated for each of the plurality of objective lenses, a stable and highly reliable control operation can be performed for each objective lens. Further, since the reaction force generated when the objective lens is selected and moved can be reduced, a compact and inexpensive objective lens driving device can be obtained.

According to the objective lens driving device of the present invention, the means for selecting the objective lens to move the objective lens in the light beam and the means for rotating the lens holder with respect to the support shaft are partially used. Since this is done, the objective lens can be moved efficiently.

According to the objective lens driving device of the present invention, since the plurality of objective lenses are provided at positions substantially symmetrical with respect to the support shaft on the lens holder, members for driving are provided symmetrically. Thus, by providing the driving members symmetrically, it is not necessary to provide additional driving members, the number of parts can be reduced, and an inexpensive small-sized objective lens driving device can be obtained.

According to the objective lens driving device of the present invention, it is provided with means for discriminating the substrate thickness of the optical information recording medium, and the objective lens is selected according to the difference in the substrate thickness and the recording density to make the light beam enter. As a result, the amount of rotation of the lens holder can be reduced, and the lens holder can be easily balanced with respect to the support shaft. Therefore, it is not necessary to provide a member such as a balancer, and an inexpensive and small-sized objective lens can be driven. The device can be obtained.

According to the objective lens driving device of the present invention, the elastic member movable in the up and down direction of the axis substantially orthogonal to the surface of the optical information recording medium, and the rotation provided on the elastic member with the axis as the fulcrum. A lens holder supported as much as possible,
A plurality of objective lenses provided on the lens holder at positions eccentric from the axis by a substantially equal distance are provided, and the objective lens is selected according to the difference in substrate thickness or recording density of the optical information recording medium, Since it is designed to move to the position to form a light spot to record and reproduce information, it has a simple structure with a small number of parts, is inexpensive and compact, and can record and reproduce optical information recording media with different substrate thicknesses. It is possible to obtain an objective lens driving device that can realize an optical information recording / reproducing device capable of performing the above.

According to the optical head device of the present invention, since the objective lenses corresponding to the different types of optical information recording media are provided exclusively, the optical lens is optimally adapted to each optical information recording medium. Spots can be formed. Therefore, good recording or reproducing characteristics can be realized by one optical head device, so that an inexpensive and compact optical information recording / reproducing device can be realized.

[Brief description of drawings]

FIG. 1 is a perspective view showing an objective lens driving device according to a first embodiment of the present invention.

FIG. 2 is an exploded perspective view showing an objective lens driving device in Embodiment 1 of the present invention.

FIG. 3 is a plan view showing an objective lens driving device in Embodiment 1 of the present invention.

FIG. 4 is a diagram showing a positional relationship among the objective lens, the lens holder, and the optical information recording medium in the objective lens driving device according to the first embodiment of the present invention.

FIG. 5 is a diagram showing a relationship between a rotation angle of a lens holder and a restoring force generated in a tracking direction in an objective lens driving device of Example 1 of the present invention.

FIG. 6 is an exploded perspective view showing an objective lens driving device in Embodiment 2 of the present invention.

FIG. 7 is a plan view showing an objective lens driving device in Embodiment 2 of the present invention.

FIG. 8 is a diagram showing a relationship between a rotation angle of a lens holder and a restoring force generated in a tracking direction in an objective lens driving device of Example 2 of the present invention.

FIG. 9 is a plan view showing an objective lens driving device in Embodiment 3 of the present invention.

FIG. 10 is a plan view showing an objective lens driving device in Embodiment 4 of the present invention.

FIG. 11 is a plan view showing an objective lens driving device in Embodiment 4 of the present invention.

FIG. 12 is a plan view showing an objective lens driving device according to a fifth embodiment of the present invention.

FIG. 13 is a plan view showing an objective lens driving device according to Example 6 of the present invention.

FIG. 14 is a plan view showing an objective lens driving device according to a seventh embodiment of the present invention.

FIG. 15 is a perspective view showing an objective lens driving device in Embodiment 8 of the present invention.

FIG. 16 is an exploded perspective view showing an objective lens driving device according to Example 8 of the present invention.

FIG. 17 is a perspective view showing an objective lens driving device in Embodiment 9 of the present invention.

FIG. 18 is a perspective view showing an objective lens driving device in Embodiment 10 of the present invention.

FIG. 19 is an exploded perspective view showing an objective lens driving device in Embodiment 11 of the present invention.

FIG. 20 is a perspective view of a conventional objective lens driving device.

FIG. 21 is a perspective view showing an optical system in a conventional optical head device.

FIG. 22 is a diagram showing a relationship between an objective lens and an optical information recording medium in a conventional optical head device.

FIG. 23 is a plan view of an optical information recording / reproducing device having a conventional objective lens driving device.

[Explanation of symbols]

1 fixed base, 2 light beam, 3, 4 objective lens,
5 spindle holding base, 6 lens holder, 7 relay board, 8a to 8d electrical connection means, 103 spindle, 10
7a, 107b Tracking magnet, 109
Relay boards, 121a, 121b Tracking coils.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masahisa Shinoda No. 1 Baba Institute of Nagaokakyo City Video Systems Development Laboratory (72) Inventor Hideaki Kobachi No. 1 Baba Institute of Nagaokakyo City Mitsubishi Electric Corporation Video System Development Laboratory

Claims (13)

[Claims] 1. A lens holder which is rotatable about an axis and is vertically movable along the axis, and a plurality of objective lenses which are provided on the lens holder at positions eccentric from the axis by a substantially equal distance. A driving device for vertically moving the lens holder along the axis and rotating the lens holder around the axis to drive a light spot on the optical information recording medium in a focal direction and a direction crossing a track; and an optical information recording medium. An objective lens which selects an objective lens according to the type of the optical information recording medium and moves it into a light beam to form a light spot to record or reproduce information. Lens drive device. 2. The objective lens driving device according to claim 1, wherein a step is provided on a mounting surface of the plurality of objective lenses provided on the lens holder. 3. The same driving device is used to perform the means for selecting the objective lens and moving the objective lens in the light flux, and the means for rotating the lens holder with respect to a support shaft. The objective lens driving device according to claim 1. 4. The midpoint restoring force generating means, the number of which is equal to or larger than the number of the objective lenses, is provided so as to generate the midpoint restoring force for each of the plurality of objective lenses. Objective lens driving device. 5. The objective lens driving device according to claim 1, further comprising means for selecting the objective lens and limiting a moving range of the objective lens. 6. The objective lens driving device according to claim 1, further comprising means for detecting which one of the plurality of objective lenses is selected. 7. The objective lens driving device according to claim 1, further comprising means for detecting a rotational position of the lens holder. 8. The objective lens driving device according to claim 1, wherein driving means for driving the lens holder in a direction traversing a track is provided in a number equal to or larger than the number of the objective lenses to be held. 9. The means for selecting the objective lens and moving the objective lens in a light beam, and the means for rotating the lens holder with respect to a support shaft, both partially serve. Objective lens driving device. 10. The objective lens driving device according to claim 1, wherein the plurality of objective lenses are provided on the lens holder at positions substantially symmetrical with respect to the support shaft. 11. A lens holder rotatably and slidably held by a support shaft, a plurality of objective lenses provided on the lens holder at positions eccentrically symmetrical with respect to the support shaft, and the lens. A driving device for driving the light spot on the optical information recording medium in a focal direction and a direction traversing the track by sliding and rotating the holder with respect to the spindle; and means for discriminating the type of the optical information recording medium. An objective-lens driving device comprising: an objective lens selected according to the type of an optical information recording medium, a light beam is made incident, a light spot is formed, and information is recorded and reproduced. 12. An elastic member, which is movable in the vertical direction of an axis substantially orthogonal to the surface of the optical information recording medium, a lens holder provided on the elastic member and rotatably supported about the axis as a fulcrum, A plurality of objective lenses provided on the lens holder at positions eccentric from the axis by a substantially equal distance, and optical information recording by moving the lens holder vertically with respect to the axis and pivoting about the axis as a fulcrum. A drive device for driving the light spot on the medium in the focal direction and the direction crossing the track and a means for discriminating the type of the optical information recording medium are provided, and the objective lens is selected according to the type of the optical information recording medium. The objective lens driving device is characterized in that it moves into a light beam to form a light spot to record / reproduce information. 13. A light source, a light beam emitted from the light source, a plurality of objective lenses provided in one lens holder, and a plurality of objective lenses provided in the lens holder are moved to generate the light beam. A unit for setting the incident position, an optical information recording medium, a unit for selecting an objective lens suitable for the optical information recording medium, and an optical system using the objective lens selected by driving the lens holder. An optical head device comprising: a drive unit that corrects a focus shift and a track shift of a light spot condensed by the objective lens on the surface of the information recording medium.