JPH09198682A - Objective lens holder of optical pickup device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the peak value while increasing higher-order resonance frequency. SOLUTION: A lens holding part 9 to hold an objective lens on the upper end face 8a side, a cylindrical bearing part 10 held to be able to turn and slide with respect to a supporting shaft fixed to the frame of an optical pickup, and a coil placing part 11 for a driving coil to be mounted on the outer peripheral surface, are formed in a thin-wall thickness state. These lens holding part 9, bearing part 10, and coil placing part 11 are coupled with each other with thin-wall reinforcement ribs 12 parallel to the center line of the bearing part 10, and at least a part of the opening end parts on the side of the upper end face 8a of the space surrounded by the outside part of the lens holding part 9, the outside part of the bearing part 10, the coil mounting part 11, and the reinforcement ribs 12 is plugged with a thin plate 13.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an objective lens holder for holding an objective lens of an optical pickup device incorporated in an optical disc device or the like. More specifically, the present invention relates to the structure of an objective lens holder.

[0002]

2. Description of the Related Art As an optical pickup device incorporated in an optical disc device for reproducing an optical disc which is a digital recording medium, a conventional optical pickup device is disclosed in, for example, Japanese Patent Laid-Open No. 7-11095.
Some are disclosed in No. 5. As shown in FIG. 12, the optical pickup device 1 includes an objective lens holder 3 which is rotatable and slidable with respect to a support shaft 2, a focusing drive coil 4 attached to an outer surface of the objective lens holder 3, Tracking drive coil 5 and drive magnet 6 arranged outside these drive coils 4 and 5.
And The objective lens holder 3 includes an objective lens 7
A lens holding portion 3a for holding, a bearing portion 3b supported by the support shaft 2, a coil arrangement portion 3c provided with the drive coils 4 and 5 on the outer surface thereof, the lens holding portion 3a, the bearing portion 3b, and the coil. A thick-walled connecting portion 3d that connects the arrangement portion 3c is provided.

[0003]

However, in the above-described optical pickup device 1, since the weight of the objective lens holder 3 is large, the high-order resonance frequency becomes small. Therefore, the objective lens holder 3 easily oscillates during the focusing operation and the tracking operation. This makes it difficult to control the position of the objective lens holder 3.

In order to increase the high-order resonance frequency, it is effective to reduce the weight of the objective lens holder 3. In order to reduce the weight of the objective lens holder 3 and to have rigidity suitable for use as the objective lens holder 3,
The lens holding portion 3a, the bearing portion 3b, and the coil arrangement portion 3c of the objective lens holder 3 are thin-walled, and the connecting portion 3d is thin-walled parallel to the support shaft 2. According to the optical pickup device 1 using the lightweight objective lens holder 3, FIG.
As shown by the broken line of, the higher resonance frequency becomes larger.

However, in this objective lens holder 3, the air resistance against deformation in the sliding direction is small. For this reason,
When the higher order resonance is generated by the focusing operation, the vibration in the sliding direction cannot be attenuated, and the peak value at the higher order resonance frequency increases. Thereby, the objective lens holder 3 easily oscillates during the focusing operation.
Therefore, it is difficult to control the position of the objective lens holder 3 even if the higher resonance frequency is increased.

Therefore, it is an object of the present invention to provide an objective lens holder which has a high resonance frequency increased and a peak value reduced.

[0007]

In order to achieve the above object, an objective lens holder of an optical pickup device according to a first aspect includes a lens holding portion for holding the objective lens on an upper end surface side,
A bearing portion that is rotatably and slidably supported on a support shaft that is fixed to the optical pickup device, and a coil arrangement portion that has a drive coil provided on the outer peripheral surface are formed thin, and a lens holding portion is also provided. A space that connects the bearing portion and the coil arrangement portion to each other with a thin reinforcing rib parallel to the center line of the bearing portion, and is surrounded by the outside of the lens holding portion, the outside of the bearing portion, the coil arrangement portion, and the reinforcing rib. At least a part of the open end on the upper end surface side of the is closed with a thin plate.

Therefore, since the lens holding portion, the bearing portion, the coil arrangement portion, and the reinforcing rib are formed in a thin shape and the thin plate is provided on the upper end surface side, the weight of the objective lens holder is reduced. Therefore, when the focusing operation is performed by the objective lens holder, the high-order resonance frequency becomes large.

Since at least a part of the open end on the upper end face side of the space surrounded by the outside of the lens holding portion, the outside of the bearing portion, the coil arrangement portion and the reinforcing rib is closed by a thin plate, the objective lens Large air resistance against deformation of holder in sliding direction. Therefore, when higher-order resonance occurs due to the focusing operation, the vibration of the objective lens holder itself in the sliding direction is attenuated, and the peak value at the higher-order resonance frequency is reduced.

Further, since the thin plate is provided, the deformation mode at the time of high-order resonance, that is, the state of wave propagation in the objective lens holder changes. Therefore, when the objective lens holder resonates with the bearing portion as a support point, the antinode of resonance goes away from the objective lens, and the peak value at the higher resonance frequency is reduced.

In the objective lens holder of the optical pickup device according to the second aspect, the reinforcing rib is formed in a straight line.
Therefore, the rigidity of the objective lens holder is further improved. As a result, when high-order resonance occurs due to the focusing operation, the vibration of the objective lens holder itself in the sliding direction is easily attenuated, and the peak value at the high-order resonance frequency is further reduced.

Further, the objective lens holder of the optical pickup device of claim 3 is rotatable and slidable with respect to a lens holding portion for holding the objective lens on the upper end surface side and a support shaft fixed to the optical pickup device. And a coil arrangement portion having a drive coil provided on the outer peripheral surface thereof are formed thin, and the lens holding portion, the bearing portion and the coil arrangement portion are parallel to the center line of the bearing portion, and They are connected to each other by linear thin-walled reinforcing ribs.

Therefore, since the reinforcing rib is linear, the rigidity of the objective lens holder is improved as compared with the case where the rib is arcuate. As a result, when high-order resonance occurs due to the focusing operation, the vibration of the objective lens holder itself in the sliding direction is easily attenuated, and the peak value at the high-order resonance frequency decreases.

Further, in the objective lens holder of the optical pickup device of claim 4, the thin plate is the lens holding portion, the bearing portion,
It is integrally formed with the coil arrangement portion and the reinforcing rib. Therefore, the rigidity of the objective lens holder is further improved because all the parts constituting the objective lens holder, including the thin plate, are integrally formed. Further, when manufacturing the objective lens holder, it is not necessary to join the individual parts, so that the manufacturing process is simplified.

Further, in the objective lens holder of the optical pickup device according to a fifth aspect, the thin plate is a member separate from the lens holding portion, the bearing portion, the coil arrangement portion and the reinforcing rib, and the lens holding portion, the bearing portion and the coil are provided. The arrangement part and the reinforcing rib are attached to a single member or a plurality of members. Therefore, when manufacturing the objective lens holder, for example, the lens holding portion, the bearing portion, the coil arrangement portion, and the reinforcing rib are integrally molded, and then the outside of the lens holding portion, the outside of the bearing portion, the coil arrangement portion, and the reinforcing rib are formed. A thin plate is attached to at least a part of the open end on the upper end surface side of the space surrounded by and.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION The structure of the present invention will be described below in detail based on the embodiments shown in the drawings.

As shown in FIG. 1, the objective lens holder 8 of the optical pickup device according to the first embodiment of the present invention includes a lens holding portion 9 for holding an objective lens (not shown) on the upper end surface 8a side. A cylindrical bearing portion 10 is rotatably and slidably supported on a support shaft (not shown) fixed to the frame of the optical pickup device, and a drive coil (not shown) is attached to the outer surface. The coil arranging portion 11 is formed thin, and the lens holding portion 9 and the bearing portion 10 are formed.
The coil arrangement portion 11 and the coil arrangement portion 11 are connected to each other by a thin reinforcing rib 12 parallel to the center line of the bearing portion 10, and outside the lens holding portion 9 and outside the bearing portion 10 and between the coil arrangement portion 11 and the reinforcement rib 12. At least a part of the opening end portion on the upper end surface 8a side of the space surrounded by and is closed by the thin plate 13.

The coil disposing portion 11 has a substantially cylindrical shape with the bearing portion 10 at the center. A focusing drive coil and a tracking drive coil (not shown) are attached to the outer surface of the coil placement portion 11 by adhesion or the like. Further, a part of the coil placement portion 11 is coupled to the outer side portion of the lens holding portion 9 having a substantially cylindrical shape.

The reinforcing ribs 12 are formed in a substantially cylindrical shape centered on the bearing portion 10 and are joined to the lens holding portion 9, and the reinforcing ribs 12 are formed radially around the bearing portion 10 and the bearing portion 10 and the cylindrical rib 12a. Inner rib 12b connecting with
And a cylindrical rib 12 formed radially around the bearing portion 10.
The outer rib 12c connects a with the coil disposition portion 11. Each reinforcing rib 12 is parallel to the center line of the bearing portion 10 and occupies from the upper end surface 8a of the objective lens holder 8 to the vicinity of the lower end surface. Therefore, the rigidity of the objective lens holder 8 can be ensured to a size suitable for use. Further, the lens holding portion 9 and the bearing portion 10,
The coil arrangement portion 11 and the reinforcing rib 12 are formed by, for example, plastic integral molding.

Here, the inner rib 12b and the outer rib 12c
The number of and may be singular or plural. Further, the inner rib 12b does not have to be radial as long as it connects the bearing portion 10 and the cylindrical rib 12a. For example, it may be a straight line parallel to the tangential direction of the outer peripheral portion of the bearing portion 10 or a curved line. On the other hand, the outer rib 12c does not have to be radial as long as it joins the cylindrical rib 12a and the coil placement portion 11. Therefore, the inner rib 1
Other shapes can be used as well as 2b. In order to balance the weight of the entire objective lens holder 8,
The coil arrangement portion 11 and the reinforcing ribs 12 should be shaped and arranged at positions that are line-symmetric with respect to the center line of the bearing portion 10, or the center line of the lens holding portion 9 and the center of the bearing portion 10. It is desirable to make the shape and arrangement position symmetrical about the plane including the line.

As shown by the hatched portion in FIG. 1B, the thin plate 13 has an upper end surface 8a of a space surrounded by the lens holding portion 9, the bearing portion 10, the coil arrangement portion 11 and the reinforcing rib 12. It is provided so as to close at least a part of the open end on the side. The thin plate 13 includes the lens holding portion 9 and the bearing portion 1.
0, the coil placement portion 11, and the reinforcing rib 12 are formed by, for example, plastic integral molding. The thin plate 13 may be a member separate from the reinforcing ribs 12 and the like. For example, the thin plate 13 is formed of an FPC (flexible printed circuit board) having a thickness of 0.8 to 0.6 mm, an aluminum foil, a top plate having the same thickness as the reinforcing ribs 12, and the like. It may be adhered or fitted by, for example.

When the above-mentioned objective lens holder 8 is incorporated into the optical pickup device to perform the focusing operation, the weight is reduced and the higher resonance frequency is increased.

Since the thin plate 13 closes the space surrounded by the lens holding portion 9, the bearing portion 10, the coil arrangement portion 11 and the reinforcing rib 12, the objective lens holder 8 slides in the sliding direction. The air resistance to deformation is large. Therefore, when high-order resonance occurs due to the focusing operation, the vibration of the objective lens holder 8 itself in the sliding direction is attenuated, and the peak value at the high-order resonance frequency is reduced.
Further, by providing the thin plate 13, the deformation mode at the time of high-order resonance, that is, the state of propagation of the resonance wave in the objective lens holder changes. Therefore, when the objective lens holder 8 resonates with the bearing portion 10 as a support point, the antinode of resonance moves away from the objective lens, and the peak value at the higher resonance frequency is reduced.

Therefore, according to the first embodiment, as shown in FIG. 2, the peak value decreases in the state where the higher-order resonance frequency increases, so that the position of the objective lens holder 8 is controlled by the focusing operation. It becomes difficult to oscillate.

Here, as shown in the figure, the gain is 0 dB.
Is defined as the gain intersection frequency Fg, and this frequency Fg can be set arbitrarily. If this gain intersection frequency Fg is set to be large,
The position control performance can be further improved. However, if the gain crossover frequency Fg is too large, the peak value of the higher resonance frequency F1 exceeds the gain crossover point (gain = 0 dB) and the control oscillates. Therefore, the higher resonance frequency F1 is increased or the peak value is increased. Therefore, the margin .DELTA.G with respect to the gain intersection of the peak value must be increased by decreasing.

Since the peak value of the high-order resonance frequency F1 is large in the past, the gain intersection frequency Fg must be set sufficiently small to secure the margin ΔG, and it is difficult to improve the position control performance. Met. On the other hand, in the present embodiment, the higher-order resonance frequency F1 can be increased and the peak value can be decreased to increase the margin ΔG, so that the gain intersection frequency Fg can be set large and the position control can be accurately performed. Like

The above embodiment is an example of a preferred embodiment of the present invention, but the present invention is not limited thereto, and various modifications can be made without departing from the gist of the present invention.

For example, the shapes of the lens holding portion 9, the bearing portion 10, the coil disposing portion 11, and the reinforcing rib 12 are not limited to the shapes of the first embodiment, and various shapes can be used.
Hereinafter, the shape of the objective lens holder 8 of each embodiment shown in FIGS. 3 to 11 will be described. However, it goes without saying that the present invention is not limited to these embodiments.

The objective lens holder 8 of the second embodiment is
As shown in FIG. 3, a bearing portion 10 and a coil arranging portion 11 having a substantially cylindrical shape centering on the bearing portion 10 are provided.
The bearing portion 10 and the coil arrangement portion 11 are
Radial ribs 12 formed every 45 degrees around the
They are connected by d. Regarding every other one of the radiation ribs 12d, the central portions thereof are connected by a linear intermediate rib 12e. A lens holding portion 9 coupled to the coil placement portion 11, the intermediate rib 12e, and the radiation rib 12d is provided at one position of the portion where the intermediate ribs 12e are orthogonal to each other.

Here, the radiating ribs 12d may be provided not every 45 degrees but every 60 degrees, for example. Further, the radial rib 12d does not have to be radial as long as it connects the bearing portion 10 and the coil arrangement portion 11. For example,
It may be a straight line parallel to the tangential direction of the outer peripheral portion of the bearing portion 10 or a curved line. On the other hand, the intermediate rib 12e
Does not need to be linear as long as it connects the radiation ribs 12d to each other. For this reason, it is possible to have another shape like the radiation rib 12d.

The objective lens holder 8 of the third embodiment is
As shown in FIG. 4, the objective lens holder 8 of the second embodiment shown in FIG. 3 is provided with a balance weight portion 12f. The balance weight portion 12f is located on the opposite side of the lens holding portion 9 with the bearing portion 10 as the center, and is formed by the concave portion of the coil arrangement portion 11. Balance weight part 12f
A metal plate 14 is attached to this by means of adhesion or the like. Therefore, the weight of the objective lens holder 8 is well balanced, and stable sliding / rotation can be performed with respect to the support shaft.

The objective lens holder 8 of the fourth embodiment is
As shown in FIG. 5, in the intermediate rib 12e of the objective lens holder 8 of the second embodiment shown in FIG. 3, the central portions of the respective radiation ribs 12d are linearly connected. on the other hand,
The intermediate rib 12e need not be linear as long as it connects the radiation ribs 12d to each other. For this reason, it is possible to have another shape like the radiation rib 12d.

The objective lens holder 8 of the fifth embodiment is
As shown in FIG. 6, the objective lens holder 8 of the fourth embodiment shown in FIG. 5 is provided with a balance weight portion 12f. The balance weight portion 12f is located on the opposite side of the lens holding portion 9 with the bearing portion 10 as the center, and is formed by the concave portion of the coil arrangement portion 11. Balance weight part 12f
A metal plate 14 is attached to this by means of adhesion or the like. Therefore, the weight of the objective lens holder 8 is well balanced, and stable sliding / rotation can be performed with respect to the support shaft.

The objective lens holder 8 of the sixth embodiment is
As shown in FIG. 7, the objective lens holder 8 of the second embodiment shown in FIG. 3 is provided with a balance weight portion 12g. The balance weight portion 12g is located on the opposite side of the lens holding portion 9 with the bearing portion 10 as the center. The balance weight portion 12g is integrally formed in a shape in which the fillet of the coupling portion between the coil arrangement portion 11 and the radiation rib 12d is thick. Therefore, the weight of the objective lens holder 8 is well balanced, and stable sliding / rotation can be performed with respect to the support shaft. Further, since it is integrally molded, the working speed of manufacturing the objective lens holder 8 can be improved.

The objective lens holder 8 of the seventh embodiment is
As shown in FIG. 8, the bearing portion 10, the lens holding portion 9,
The lens holding portion 9 has a substantially cylindrical shape centered on the bearing portion 10.
And a coil arrangement portion 11 that is coupled to. The bearing portion 10, the lens holding portion 9, and the coil arrangement portion 11 are connected by a reinforcing rib 12. The reinforcing rib 12 is formed in a substantially cylindrical shape around the bearing portion 10 and is coupled to the lens holding portion 9, and is radially formed around the bearing portion 10 to connect the bearing portion 10 and the cylindrical rib 12 a. The inner rib 12b and the outer rib 12c that are formed substantially radially around the bearing portion 10 and connect the cylindrical rib 12a and the coil disposition portion 11 to each other.

Here, the inner rib 12b and the outer rib 12c
The number of and may be singular or plural. Further, the inner rib 12b does not have to be radial as long as it connects the bearing portion 10 and the cylindrical rib 12a. For example, it may be a straight line parallel to the tangential direction of the outer peripheral portion of the bearing portion 10 or a curved line. On the other hand, the outer rib 12c does not have to be radial as long as it joins the cylindrical rib 12a and the coil placement portion 11. Therefore, the inner rib 1
Other shapes can be used as well as 2b.

The objective lens holder 8 of the eighth embodiment is
As shown in FIG. 9, the bearing portion 10, the lens holding portion 9,
The lens holding portion 9 has a substantially cylindrical shape centered on the bearing portion 10.
And a coil arrangement portion 11 that is coupled to. The bearing portion 10, the lens holding portion 9, and the coil arrangement portion 11 are connected by a reinforcing rib 12. The reinforcing rib 12 is substantially parallel to a plane including the center line of the lens holding portion 9 and the center line of the bearing portion 10, and is a vertical portion that connects both side portions of the lens holding portion 9 and the bearing portion 10 to the coil disposing portion 11. Rib 12
h, and horizontal ribs 12 that connect the vertical ribs 12h, which are substantially orthogonal to the vertical ribs 12h, and the coil placement portions 11 facing each other,
i and an auxiliary rib 12j that is obliquely connected to reinforce the connecting portion of the vertical rib 12h and the horizontal rib 12i.

Here, the number of the lateral ribs 12i and the auxiliary ribs 12j may be singular or plural. Also, the horizontal rib 12
i does not need to be substantially orthogonal to the vertical rib 12h as long as it connects the vertical rib 12h and the coil disposition portion 11. For example, it may be a straight line parallel to the tangential direction of the outer peripheral portion of the bearing portion 10 or a curved line. On the other hand, the auxiliary rib 12j may be any shape as long as it connects the vertical rib 12h and the horizontal rib 12i, and can have another shape like the horizontal rib 12i.

The objective lens holder 8 of the ninth embodiment is
As shown in FIG. 10, the objective lens holder 8 of the second embodiment shown in FIG. 3 is provided with another lens holding portion 15.
The other lens holding portion 15 is arranged around an orthogonal position adjacent to the orthogonal position between the intermediate ribs 12e on which the one lens holding portion 9 is arranged. Further, the bearing portion 10 of the radiating rib 12d arranged between the two lens holding portions 9 and 15
The radiating rib 12d located on the opposite side with respect to is sandwiched between the intermediate rib 12e and the coil placement portion 11. Therefore, a space is formed between the intermediate rib 12e and the bearing portion 10. This space can be used as a housing portion 12k for housing the lead wire of each drive coil.

Objective lens holder 8 of the tenth embodiment
As shown in FIG. 11, the bearing portion 10 and the bearing portion 10
A substantially cylindrical coil arrangement portion 11 centered around the bearing portion 10, and the bearing portion 1 radially formed around the bearing portion 10 every 45 degrees.
A radiation rib 12d that connects 0 and the coil placement portion 11;
It is provided with a cylindrical rib 12a which is formed in a substantially cylindrical shape centered on the bearing portion 10 and connects the central portions of the respective radiation ribs 12d. The first lens holding portion 9 is formed around the coupling position between the one radiation rib 12d and the coil arrangement portion 11. Radiation rib 12d on which the first lens holding portion 9 is formed
The second lens holding portion 15 is formed around the coupling position of the radiation rib 12d and the coil arrangement portion 11 which are deviated by 90 degrees. The radiation rib 12d located between the two lens holding portions 9 and 15 on the opposite side of the bearing portion 10 of the radiation rib 12d is formed between the cylindrical rib 12a and the coil placement portion 11. ing. The space between the cylindrical rib 12a and the bearing 10 serves as a housing 12k that houses the lead wire of the drive coil. Further, a balance weight portion 12g having a thick fillet is formed on the inner side surface of the coil disposing portion 11 on the opposite side of the bearing portions 10 of the lens holding portions 9 and 15.

Here, the radiating ribs 12d are not limited to those formed every 45 degrees, and may be formed every 60 degrees, for example. Further, the radial rib 12d does not have to be radial as long as it connects the bearing portion 10 and the coil arrangement portion 11. For example, it may be a straight line parallel to the tangential direction of the outer peripheral portion of the bearing portion 10 or a curved line. On the other hand, the cylindrical rib 12a need not have a cylindrical shape as long as it connects the radiation ribs 12d to each other. For this reason, it is possible to have another shape like the radiation rib 12d.

Objective lens holder 8 of the eleventh embodiment
As shown in FIG. 14, the bearing portion 10 and the bearing portion 10
A substantially cylindrical coil arrangement portion 11 centered on the center of the bearing, and a radial rib radially formed around the bearing portion 10 so as to divide the circumference into seven at intervals of about 50 degrees, and connect the bearing portion 10 and the coil arrangement portion 11 to each other. 12d. Then, the coil arrangement portion 1 between the pair of adjacent radiating ribs 12d, 12d
A first lens holding portion 9 is formed around the center of 1. Further, the second lens holding portion 15 is formed around a position that is deviated by 90 degrees from the position where the first lens holding portion 9 is formed with the bearing portion 10 as the center. further,
The bearing portion 10 is sandwiched between the first lens holding portion 9 and the second lens holding portion 15 at a position offset by 135 degrees from the first lens holding portion 9 as a center, that is, at an intermediate position between the lens holding portions 9 and 15. A balance weight portion 12g having a thick fillet is formed at the side position. In addition, the intermediate rib 1 is provided along a straight line connecting the centers of the lens holding portions 9 and 15.
2e is formed. Furthermore, the balance weight section 1
Linear slanted ribs 12m, 12m that connect 2g with the lens holding portions 9, 15 are formed.

In the objective lens holder 8 of the second to eleventh embodiments described above, the weight is reduced, and the thin plate 13 is provided outside the lens holding portion 9, outside the bearing portion 10, the coil arrangement portion 11, and the reinforcing rib 12. Since the space surrounded by and is closed, like the objective lens holder 8 of the first embodiment,
The higher resonance frequency can be increased and its peak value can be decreased. For this reason, it becomes difficult to oscillate when controlling the position of the objective lens holder 8, and the position can be controlled easily and accurately.

Further, a ninth embodiment shown in FIG. 10 and FIG.
In the tenth embodiment shown in FIG. 1 and the eleventh embodiment shown in FIG. 14, since two first and second lens holding portions 9 and 15 are provided, two types of objective lenses are switched and used. be able to. For example, if one lens holding unit is DV
The objective lens for D is attached, and the CD is attached to the other lens holder.
The objective lens can be switched and used by attaching an objective lens for the use and rotating the bearing 10 by 90 degrees.

Therefore, also in the two-lens-mounting objective lens holder 8, the higher-order resonance frequency is increased by reducing the weight of the objective-lens holder 8 and the peak value at the higher-order resonance frequency is reduced by the air resistance of the thin plate 13. Can be achieved. As a result, even in the two-lens-mounting objective lens holder 8, oscillation when controlling the position of the objective lens holder 8 during the focusing operation is suppressed.

In the objective lens holder 8 of the first to eleventh embodiments described above, the mounting range of the thin plate 13 is a range outside the lens holding section 9 and the bearing section 10 and surrounded by the coil disposing section 11. However, it is not limited to this. For example, when applied to an optical pickup device in which the inner yoke penetrates the yoke hole of the objective lens holder 8 and is exposed to the upper end surface 8a of the objective lens holder 8, the thin plate 13 is removed except for the yoke hole through which the inner yoke penetrates. Set up. Further, in the objective lens holder 8 having a through hole through which the lead wire of each drive coil is inserted into and out of the objective lens holder 8, the thin plate 13 is provided except for this through hole.

The thin plate 13 may be provided only on a part of the upper end surface 8a of the objective lens holder 8. For example, it can be provided only on the predetermined reinforcing rib 12. Further, in the case of an optical pickup device in which the support shaft does not pass through the upper end side of the bearing portion 10, the thin plate 13 may be provided on the upper surface of the bearing portion 10.

Furthermore, in each of the above-described embodiments, the objective lens holder 8 is provided with the thin plate 13 and the reinforcing ribs 12 are linear or arcuate, but the present invention is not limited to this, and the objective lens holder 8 is not limited to this. Alternatively, the reinforcing ribs 12 may not be provided and the reinforcing ribs 12 may have only a linear shape. For example, the second embodiment shown in FIG. 3, the third embodiment shown in FIG. 4, the fourth embodiment shown in FIG. 5, the fifth embodiment shown in FIG. 6, and the sixth embodiment shown in FIG. The case corresponds to the case where the thin plate 13 of the objective lens holder 8 is omitted in the form, the eighth embodiment shown in FIG. 9, the ninth embodiment shown in FIG. 10, and the eleventh embodiment shown in FIG.

In this case, in any of the embodiments, the reinforcing rib 12 is linear, and the lens holding portion 9 and the bearing portion 1 are provided.
0 and the coil arranging portion 11 are thin, the reinforcing ribs 12
The rigidity of the objective lens holder 8 is improved as compared with the case where is a circular arc shape. Accordingly, when high-order resonance occurs due to the focusing operation, the vibration of the objective lens holder 8 itself in the sliding direction is easily attenuated, and the peak value at the high-order resonance frequency can be reduced.

[0050]

As is clear from the above description, in the objective lens holder of the optical pickup device according to the first aspect, the lens holding portion, the bearing portion, the coil arrangement portion, and the reinforcing rib are formed thinly and Since the thin plate is provided on the end face side, the weight of the objective lens holder can be reduced. Therefore, when the focusing operation is performed by the objective lens holder, the higher resonance frequency can be increased.

Since at least a part of the open end on the upper end face side of the space surrounded by the outside of the lens holding portion, the outside of the bearing portion, the coil arrangement portion and the reinforcing rib is closed with a thin plate, the objective lens Large air resistance against deformation of holder in sliding direction. Therefore, when high-order resonance occurs due to the focusing operation, the vibration of the objective lens holder itself in the sliding direction is attenuated, and the peak value at the high-order resonance frequency can be reduced.

Further, by providing the thin plate, the deformation mode at the time of high-order resonance, that is, the state of propagation of the resonance wave in the objective lens holder changes. Therefore, when the objective lens holder resonates with the bearing portion as a support point, the antinode of resonance moves away from the objective lens, and the peak value at the higher resonance frequency can be reduced.

Therefore, as shown in FIG. 2, the peak value decreases in the state where the higher-order resonance frequency is increased, so that the oscillation becomes difficult when controlling the position of the objective lens holder by the focusing operation.

Here, as shown in the figure, the gain is 0 dB.
If the gain intersection frequency Fg is set to a large value, the position control performance can be further improved. However, if the gain crossover frequency Fg is too large, the higher resonance frequency F
Since the peak value of 1 exceeds the gain intersection (gain = 0 dB) and the control oscillates, the higher resonance frequency F1
Must be increased or the peak value must be decreased to increase the margin ΔG with respect to the gain intersection of the peak value. According to the present invention, the higher-order resonance frequency F1 can be increased and the peak value can be decreased to increase the margin ΔG, so that the gain intersection frequency Fg can be set large and the position control can be accurately performed. Become.

Further, in the objective lens holder of the optical pickup device according to the second aspect, since the reinforcing rib is formed linearly, the rigidity of the objective lens holder is further improved. Accordingly, when high-order resonance occurs due to the focusing operation, the vibration of the objective lens holder itself in the sliding direction is easily attenuated, and the peak value at the high-order resonance frequency can be further reduced.

Further, in the objective lens holder of the optical pickup device of the third aspect, the lens holding portion for holding the objective lens, the bearing portion supported by the support shaft, and the coil arrangement portion provided with the drive coil are thin-walled. And the lens holding portion, the bearing portion, and the coil arrangement portion are connected to each other by a thin reinforcing rib that is parallel to the center line of the bearing portion and is linear, so that the rib has an arc shape. The rigidity of the objective lens holder is improved as compared with the case. As a result, when high-order resonance occurs due to the focusing operation, the vibration of the objective lens holder itself in the sliding direction is easily attenuated, and the peak value at the high-order resonance frequency can be reduced.

Further, in the objective lens holder of the optical pickup device according to the fourth aspect, the thin plate is the lens holding portion, the bearing portion,
Since it is integrally formed with the coil arrangement portion and the reinforcing ribs, all the parts constituting the objective lens holder are integrally formed including the thin plate, and the rigidity of the objective lens holder can be further improved. it can. Moreover, when manufacturing the objective lens holder, it is not necessary to join the individual parts, so that the manufacturing can be performed easily and quickly.

Furthermore, in the objective lens holder of the optical pickup device of the fifth aspect, the thin plate is a separate body from the lens holding portion, the bearing portion, the coil arrangement portion, and the reinforcing rib. Therefore, when manufacturing the objective lens holder, for example, the lens holding portion, the bearing portion, the coil arrangement portion, and the reinforcing rib are integrally formed, and then a thin plate is formed at one end portion or both end portions in the center line direction of the bearing portion. Install. Therefore, it is possible to use a high-quality thin plate having uniform thickness and strength, and it is possible to effectively reduce the weight and increase the rigidity. Further, the most suitable thin plate can be selected and used according to the application.

[Brief description of drawings]

1A and 1B show a first embodiment of an objective lens holder of the present invention, FIG. 1A is a sectional view taken along line I-I, and FIG. 1B is a plan view.

FIG. 2 is a Bode diagram showing the relationship between the input frequency to the focusing drive coil and the gain.

3A and 3B show a second embodiment of the objective lens holder of the present invention, FIG. 3A is a sectional view taken along line III-III, and FIG. 3B is a plan view.

FIG. 4 shows a third embodiment of an objective lens holder of the present invention, (A) is a sectional view taken along line IV-IV, and (B) is a plan view.

5A and 5B show a fourth embodiment of an objective lens holder of the present invention, FIG. 5A is a sectional view taken along line VV, and FIG. 5B is a plan view.

FIG. 6 shows a fifth embodiment of the objective lens holder of the present invention, (A) is a sectional view taken along line VI-VI, and (B) is a plan view.

FIG. 7 shows a sixth embodiment of the objective lens holder of the present invention, (A) is a sectional view taken along line VII-VII, and (B) is a plan view.

FIG. 8 shows a seventh embodiment of the objective lens holder of the present invention, (A) is a sectional view taken along the line VIII-VIII, and (B) is a plan view.

9A and 9B show an eighth embodiment of the objective lens holder of the present invention, FIG. 9A is a sectional view taken along line IX-IX, and FIG. 9B is a plan view.

FIG. 10 shows a ninth embodiment of the objective lens holder of the present invention, (A) is a cross-sectional view taken along line XX, and (B) is a plan view.

FIG. 11 shows a tenth embodiment of the objective lens holder of the present invention, (A) is a sectional view taken along line XI-XI, and (B) is a plan view.

FIG. 12 is a plan view showing a conventional optical pickup device.

FIG. 13 is a Bode diagram showing the relationship between the input frequency and the gain of a conventional focusing drive coil.

FIG. 14 shows an eleventh embodiment of an objective lens holder of the present invention, (A) is a cross-sectional view taken along line XIV-XIV, and (B) is a plan view.

[Explanation of symbols]

 8 Objective Lens Holder 8a Upper End Surface 9 First Lens Holding Section 10 Bearing Section 11 Coil Arrangement Section 12 Reinforcing Rib 13 Thin Plate 15 Second Lens Holding Section

Claims (5)

[Claims] 1. A lens holding portion for holding an objective lens on an upper end surface side, a bearing portion rotatably and slidably supported on a support shaft fixed to an optical pickup device, and a drive coil on an outer peripheral surface. Is formed thinly with the coil arrangement portion, and the lens holding portion, the bearing portion and the coil arrangement portion are mutually connected by a thin-walled reinforcing rib parallel to the center line of the bearing portion, and An optical pickup device characterized in that at least a part of an opening end portion on the upper end surface side of a space surrounded by the outside of the lens holding portion, the outside of the bearing portion, the coil arrangement portion and the reinforcing rib is closed by a thin plate. Objective lens holder. 2. The objective lens holder of the optical pickup device according to claim 1, wherein the reinforcing rib is formed in a linear shape. 3. A lens holding portion for holding an objective lens on an upper end surface side, a bearing portion rotatably and slidably supported on a support shaft fixed to an optical pickup device, and a drive coil on an outer peripheral surface. Is formed thinly, and the lens holding portion, the bearing portion, and the coil arrangement portion are mutually parallel to each other with a linear thin reinforcing rib parallel to the center line of the bearing portion. An objective lens holder for an optical pickup device, which is connected. 4. The optical pickup according to claim 1, wherein the thin plate is integrally formed with the lens holding portion, the bearing portion, the coil arrangement portion, and the reinforcing rib. Objective lens holder of the device. 5. The thin plate is a separate body from the lens holding portion, the bearing portion, the coil arrangement portion, and the reinforcing rib, and the lens holding portion, the bearing portion, the coil arrangement portion, and the reinforcement portion. The rib is attached to one or a plurality of members among the ribs.
Alternatively, the objective lens holder of the optical pickup device according to claim 2.