JPH11353675A - Optical pickup device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent deterioration in lens performance by forming a through hole part on a holder so as to be placed in the vicinity of an objective lens and nearly uniformizing a temp. distribution in the objective lens. SOLUTION: The through hole parts 30 are formed, on the holder 13 of a biaxial actuator 11, with a prescribed length in the front/rear direction and in a slit shape of prescribed with in the lateral direction so as to be placed between yoke insertion holes 16 of front/rear parts and between both sides of the objective lens 12 and both side winding parts of a focus coil 14 being a winding wire part of a drive coil. A conduction amount of heat due to heat generation in the drive coil to the objective lens 12 is reduced, and the heat conducted uniformly from four directions to the objective lens 12, and an astigmatism temp. distribution is reduced. Vent parts are formed on a thermal conduction part to the objective lens 12 of the holder 13 in the actuator 11, and the objective lens 12 isn't affected by the heat from the drive coil in a refractive index by the reduction in the thermal conductive amount and the uniformization in the temp. distribution, and the deterioration in the lens performance is suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical pickup device applied to an optical information recording / reproducing apparatus for recording / reproducing a disk-shaped optical recording medium such as an optical disk, a magneto-optical disk and the like.

[0002]

2. Description of the Related Art An optical information recording / reproducing apparatus (hereinafter, referred to as an optical disk device) is an optical pickup for rotating a disk-shaped optical recording medium (hereinafter, referred to as an optical disk) such as an optical disk or a magneto-optical disk. The apparatus is configured to irradiate and reflect laser light by a device, receive the reflected light, and record and reproduce information.

An optical pickup device provided in this optical disk device is provided with an objective lens in the optical axis direction (focus direction) and an optical axis direction in order to accurately irradiate a laser beam to a predetermined position on the optical disk during recording and reproduction. It is driven to move in two directions perpendicular to the axis, that is, in the radial direction (tracking direction) with respect to the recording surface of the optical disk.

The movement of the objective lens in the biaxial directions is
This is performed by a two-axis actuator. In FIG. 6, a known two-axis actuator 1 that shows an arrow a as a forward direction and an arrow b as a backward direction has a lens holder 3 for holding an objective lens 2 and this lens holder 3 in a biaxial direction with respect to the base body.
That is, four substantially parallel metal wires 4a, 4b, 4 that are movably supported in the focus direction and the tracking direction.
c, 4d suspension 4 and lens holder 3
A focus coil 5 wound around the outer periphery of the lens 2 in a direction orthogonal to the optical axis direction of the objective lens 2; a tracking coil 6 separately wound and fixed on the front and rear sides of the lens holder 3 in reverse winding directions; Yoke insertion holes 7 formed opposite to each other with the objective lens 2 sandwiched between
, An outer yoke 9 corresponding to each of the inner yokes 8 facing the front side and the rear side of the lens holder 3, and a tracking coil 6 fixed to the inner side of the outer yoke 9. The magnets 10 are opposed to each other and form a magnetic circuit together with the inner and outer yokes 8 and 9.

[0005] In the biaxial actuator 1 configured as described above, the focus servo signal current and the tracking servo signal current are supplied to the focus coil 5 and the tracking coil 6. Driven. In other words, the lens holder 3 is driven in focus and tracking integrally with the objective lens 2 against the elastic force of the suspension 4, and the laser beam is spot-irradiated through the objective lens 2 to a predetermined position on the optical disk to be rotationally driven. Recording or reproduction is performed.

[0006]

The optical pickup device constructed as described above is used in a CD-ROM or the like.
In order to continuously drive the optical pickup device at high speed, the two-axis actuator 1 for driving the focus and tracking of the objective lens 2 must also be driven at high speed. Therefore, the focus coil 5 and the tracking coil 6, a large current flows. When a large current flows through the coils 5 and 6, the coil itself generates heat, and this heat is transmitted to the objective lens 2 via the lens holder 3.

As shown in FIG. 6, the objective lens 2 is separated from the coils 5 and 6 in the front-rear direction (12-6 o'clock direction of the clock) due to the heat transfer by the heat generated by the coil itself, and the yoke is provided between the coil and the coil. Due to the presence of the insertion holes 7, 7, the temperature is low, and on the other hand, on both sides (clockwise 3-9 o'clock direction)
In this case, a phenomenon in which the temperature rises due to the close proximity of the focus coil 5 appears.

For this reason, the temperature difference of the objective lens 2 affects the refractive index, astigmatism occurs, and the lens performance may be degraded.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and provides an optical pickup device in which the temperature transmitted from the holder side to the objective lens is substantially equalized to prevent the lens performance from deteriorating. Aim.

[0010]

In order to achieve the above object, an optical pickup device according to the present invention comprises an objective lens, a holder for holding the objective lens, and an optical axis direction of the objective lens and a direction orthogonal to the optical axis. A supporting member movably supported on the holder, a driving coil provided in the holder and driven in the moving direction, and a magnetic circuit including a magnet and a yoke. The holder has a through hole located near the objective lens. A part is formed so as to make the temperature distribution of the objective lens substantially uniform.

In the above configuration, the through-hole portion is formed in a slit shape opposite to the yoke insertion hole of the magnetic circuit formed opposite to the holder with the objective lens interposed therebetween with the objective lens interposed therebetween. Is preferred.

[0012] In the above structure, the through hole may be formed in a wide portion of the holder holding the objective lens and formed in a through hole shape near the objective lens. The holder can be formed in a notch shape so as to communicate with a yoke insertion hole of a magnetic circuit formed in the holder at a wide portion of the holder holding the objective lens.

In the optical pickup device according to the present invention having the above-described structure, by forming the through hole in the holder, the amount of heat conduction to the objective lens is reduced, and the heat is evenly transmitted and the temperature distribution is uniform. The deterioration of the performance of the objective lens can be suppressed without affecting the refractive index.

Also, the through-hole is formed in the holder in a slit shape in a direction perpendicular to the yoke insertion hole with the objective lens interposed therebetween, so that the objective lens can be moved in the front-rear direction (12-6 o'clock direction of the timepiece). ) And the temperature distribution in the horizontal direction (3-9 o'clock direction of the timepiece) are almost completely equalized, and the performance deterioration of the objective lens is suppressed.

Further, the cross-sectional area of the holder is reduced by forming a through hole as a through hole or forming a notch communicating with the yoke insertion hole in a wide portion of the holder holding the objective lens. The amount of heat conduction is reduced, and the performance deterioration of the objective lens is suppressed.

[0016]

FIG. 1 is a block diagram showing an embodiment of the present invention.
5 to FIG. 7, FIG. 7, and FIG. 8, this embodiment constitutes a two-axis actuator for supporting an objective lens in the optical pickup device according to the present invention.

FIG. 1 is a perspective view of an example of a biaxial actuator applied to an optical pickup device according to the present invention, FIG. 2 is an exploded perspective view thereof, FIG. 3 is an enlarged sectional view taken along line AA of FIG. 1, and FIG. 1 is an enlarged cross-sectional view taken along the line BB of FIG. 1, and FIG. 5 is an enlarged plan view partially omitted.

In FIGS. 1 to 5, reference numeral 11 denotes the entirety of an example of a biaxial actuator, and FIGS.
, Arrows a and b indicate a forward direction and a backward direction of the biaxial actuator. In this two-axis actuator 11, a holder 13 holding an objective lens 12 also serves as a winding bobbin of a driving coil, and a focus coil is provided on an outer peripheral surface of the holder 13 in a direction orthogonal to the optical axis direction of the objective lens 12. A tracking coil 15 which is separately wound in opposite directions to each other is fixed to both front and rear sides.

At the front and rear portions of the holder 13, there are formed yoke insertion holes 16 into which an inner yoke of a magnetic circuit described later is inserted. A suspension 17 consisting of 17a, 17b, 17c, and 17d has a fixed block 1 at its distal end.
8 and each coil 1
4, 15 coil ends are electrically connected. The suspension 17 is extended rearward of the holder 13, and its base end is provided with a damper material 2 provided in a support substrate 19 in a filled state.
0 and is fixed to a fixed substrate 21 also serving as a terminal substrate fixed to the back side of the support substrate 19.
Side is electrically connected to the power supply terminal 22.

Thus, the holder 13 holding the objective lens 12 is movably supported on the support substrate 19 and the fixed substrate 21 in the optical axis direction of the objective lens 12 and in a direction orthogonal to the optical axis, that is, in a focus direction and a tracking direction. Is done.

The magnetic circuit 23 is formed by a pair of front and rear magnets 24 and a yoke 25. The yoke 25 is inserted into a horizontal plate 26 and an inner yoke 27 inserted into the yoke insertion holes 16 at the front and rear of the holder 13. An outer yoke 28 is formed upright at predetermined intervals on the outer side of the inner yoke 27, that is, on the front side and the rear side, and on the inner surface side of the outer yoke 28,
The magnet 24 is fixed to a surface facing the inner yoke 27.

The yoke 25 is fixed on a plate-like base 29, and a support substrate 19 and a fixed substrate 21 are provided on the rear of the plate-like base 29 with the holder 13 on the yoke 25 and the yoke insertion hole 1.
6 with the inner yoke 27 inserted and arranged in the upright position.
However, in the biaxial actuator 11 of this embodiment, a through hole 30 is formed in the holder 13 near the objective lens 12, and the objective lens 12 Are arranged so that the temperature distribution can be set substantially uniformly.

That is, in this embodiment, 2
In the holder 13 of the shaft actuator 11, a through hole is provided between both sides of the objective lens 12 and both side winding portions of the focus coil 14, which is a winding portion of the drive coil, between the front and rear yoke insertion holes 16. The portions 30, 30 are formed in a slit shape having a required length in the front-rear direction and a required width in the lateral direction.

As described above, the slit-shaped through holes 30, 30 are provided in the holder 13 of the biaxial actuator 11 between the yoke insertion holes 16, 16 on the front and rear sides of the objective lens 12 on both sides.
As a result, as shown in FIG. 6, in the conventional two-axis actuator 1, a ventilation portion is formed in the heat conducting portion of the holder 3 with respect to the objective lens 2, and the cross-sectional area of this portion is reduced. As shown in FIG. 5, the amount of heat conduction due to the heat generated by the drive coil with respect to the objective lens 12 is reduced, and the heat is evenly transmitted to the objective lens 12 from four directions, so that the astigmatic temperature distribution is reduced.

Therefore, the objective lens 12 has little influence on the refractive index due to the heat generated from the drive coil due to the reduction of the amount of heat conduction and the equalization of the temperature distribution, and the deterioration of the lens performance is suppressed.

In this configuration, the shape and dimensions of the through holes 30, 30 of the holder 13 are appropriately set according to the size of the holder 13 and the like. And the through hole 3
It is preferable that the reference numerals 0 and 30 are formed so as to be close to the front and rear yoke insertion holes 16 and 16 from both sides of the objective lens 12.

Further, the biaxial actuator 11 of this embodiment has the holder 13 having the front and rear yoke insertion holes 16 and 1.
By forming slit-shaped through-holes 30 on both side portions between the six, even if vibration occurs due to the center of both side surfaces of the holder 13 serving as an antinode of secondary resonance, the vibration is generated in a slit shape. The transmission of vibration to the objective lens 12 by being blocked by the through holes 30 can be effectively reduced.

Moreover, the portion between the front and rear ends of the slit-shaped through-holes 30, 30 and the yoke insertion holes 16, 16 is a node of secondary resonance and hardly generates vibration. Vibration is hardly transmitted to the objective lens 12 side. As a result, only a very small vibration component is generated in the objective lens 12, and this vibration component does not affect the recording / reproducing operation of the objective lens 12 at all.

FIGS. 7 and 8 show another example of a biaxial actuator according to an embodiment of the present invention, in which an objective lens is mounted on the first half of the holder and a drive coil is provided on the second half. Things. 7 and 8, arrows a and b indicate the front and rear directions of the biaxial actuator.

That is, in the biaxial actuator 31 shown in FIG. 7, the objective lens 32 is mounted on the first half of the holder 33, and the focus coil 34 as a driving coil is mounted on the second half.
And a tracking coil 35. The drive coil is configured by winding a focus coil 34 around the bobbin 36 in the circumferential direction, separately winding the tracking coil 35 in the opposite direction and fixing the tracking coil 35 to the front side of the bobbin 36, Opening 3 formed over
The bobbin 36 is fitted and fixed to the rear half of the device 7.

The holder 33 is supported movably in the optical axis direction of the objective lens 32 (focus direction) and the direction orthogonal to the optical axis (tracking direction) via a suspension (not shown) with respect to the base body. It corresponds to the magnetic circuit 40 formed by the magnet 39. The magnetic circuit 40 is configured such that the front yoke 38 a
7, and a rear yoke 38b having a magnet 39 fixed to the front side is inserted into the hollow portion 36a of the bobbin 36 to correspond to the holder 33 side.

In this embodiment, through holes 41 are formed in the holder 33 on both sides of the wide portion 33a near the objective lens 32. This through hole 41 is used for the holder 3
It is preferable to form the sheet 3 as large as possible without impairing the strength.

Also in the biaxial actuator 31 of this embodiment configured as described above, the through-hole 41 is formed in the wide portion 33a near the objective lens 32 in the holder 33, so that the wide portion 33a is cut off. The area is reduced, the amount of heat conduction due to the heat generated by the drive coil to the objective lens 32 side is reduced, and the temperature distribution is almost equalized without the objective lens 32 becoming partially high in temperature, as described above. Performance degradation of the objective lens 32 is suppressed.

The two-axis actuator 42 shown in FIG.
Since the general configuration is substantially the same as that of the biaxial actuator 31 shown in FIG. 7 described above, the same members are denoted by the same reference numerals and description thereof will be omitted.

The biaxial actuator 4 of this embodiment
In FIG. 2, instead of the through-hole 41 in the biaxial actuator 31 shown in FIG. 7 described above, a wide portion 33 a near the objective lens 32 from the front edge side of the opening 37 of the holder 33.
Are formed with cutouts 43 communicating with the openings 37 on both sides. Also in this case, it is preferable that the notch 43 be formed large as long as the strength of the holder 33 is not impaired.

Also in the two-axis actuator 42 of this embodiment configured as described above, the notch 43 reduces the cross-sectional area of the wide portion 33a near the objective lens 32, and moves toward the objective lens 32. Is reduced, the temperature distribution of the objective lens 32 is substantially equalized, and the performance of the objective lens 32 is prevented from deteriorating.

The embodiment of the present invention has been described above.
The present invention is not limited to the illustrated embodiment, and can be variously modified without departing from the gist of the present invention.

For example, the shape and the like of the holder can be arbitrarily changed, and the suspension is not limited to a metal wire, and a leaf spring, a resin suspension or the like can be applied.

[0039]

As described above, according to the optical pickup device of the present invention, the through-hole portion is formed near the objective lens in the holder for holding the objective lens of the biaxial actuator, so that the The cross-sectional area of the nearby part is reduced, the amount of heat conducted by the heat generated by the drive coil to the objective lens is reduced, and the temperature distribution is equalized without the objective lens becoming partially hot and the refractive index is affected. Thus, deterioration of the lens performance is suppressed, and the requirements for high accuracy and large current application of the biaxial actuator can be sufficiently satisfied, and a highly reliable optical pickup device can be obtained.

In the second aspect, the through hole is located between the yoke insertion holes and is formed in a slit shape with the objective lens interposed therebetween, so that the amount of heat conduction is reduced and the objective lens is formed. On the other hand, the heat is uniformly transmitted from four directions, the astigmatic temperature distribution is reduced, and the deterioration of the lens performance can be suppressed more reliably. In the third and fourth aspects, since the through-hole portion can be formed corresponding to the shape of the holder, it is possible to suppress the deterioration of the lens performance in the optical pickup devices of various forms.

[Brief description of the drawings]

FIG. 1 is a perspective view of an example of a biaxial actuator applied to an optical pickup device according to the present invention.

FIG. 2 is an exploded perspective view of the biaxial actuator shown in FIG.

FIG. 3 is an enlarged sectional view taken along line AA in FIG.

FIG. 4 is an enlarged sectional view taken along line BB in FIG. 1;

FIG. 5 is an enlarged plan view of a main part of the two-axis actuator shown in FIG.

FIG. 6 is a partially omitted plan view of a conventional two-axis actuator.

FIG. 7 is a plan view of another example of a biaxial actuator applied to the optical pickup device according to the present invention.

FIG. 8 is a plan view of a biaxial actuator of still another example applied to the optical pickup device according to the present invention.

[Explanation of symbols]

11, 31, 42 ‥‥ 2-axis actuator, 12, 32
{Objective lens, 13, 33} Holder, 16} Yoke insertion hole, 30} Through hole, 33a {Wide portion, 37}
{Opening, 41} Through hole, 43} Notch

Claims (4)

[Claims] An objective lens, a holder for holding the objective lens, a support member for movably supporting the holder in an optical axis direction of the objective lens and in a direction orthogonal to the optical axis, and provided in the holder in the moving direction. What is claimed is: 1. An optical pickup device comprising: a driving coil to be driven; and a magnetic circuit including a magnet and a yoke, wherein a through hole is formed in the holder near the objective lens, and a temperature distribution of the objective lens is formed. An optical pickup device characterized by substantially equalizing. 2. The through-hole portion is located between yoke insertion holes of the magnetic circuit formed opposite to the holder with the objective lens interposed therebetween, and the object is provided in a direction orthogonal to the yoke insertion hole. 2. The optical pickup device according to claim 1, wherein the optical pickup device is formed in a slit shape facing the lens. 3. The apparatus according to claim 1, wherein the through hole is formed in a wide portion of a portion of the holder that holds the objective lens, and is formed in a through hole shape near the objective lens. An optical pickup device as described in the above. 4. A notch formed in the wide portion of the holder for holding the objective lens, wherein the through hole communicates with a yoke insertion hole of the magnetic circuit formed in the holder. The optical pickup device according to claim 1, wherein: