JPH0944878A - Object lens supporting device for information storage device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an object lens supporting device capable of making an information storage device thin. SOLUTION: In a lens holder 30 supporting an object lens 1, step parts 30h are formed on its both side parts, and the upper part width of the lens holder 30 is made narrower than the lower part width in the minor axial direction. Then, when the object lens supporting device 100 is arranged on a part of an access window of an optical disk cartridge, even if the upper part of the object lens supporting device 100 is arranged while entering the access window, a required gap between the side part of the lens holder 30 and the edge of the access window is easily secured in the state that the object lens supporting device 100 comes closest to the edge of the access window. Thus, the object lens supporting device 100 can be put close to an optical disk so that it is arranged in the state of entering the access window, and the information storage device can be made thinner. Then, since the lower part width of the lens holder 30 becomes winder, the rigidity isn't lowered, and no useless secondary vibration on the lens holder 30 occurs.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information storage device, and more particularly to an objective lens support device for making light incident on an information recording medium for reading or writing information.

[0002]

2. Description of the Related Art Compact discs (CDs), video discs, magneto-optical discs, phase change discs, etc. (herein, these are collectively referred to as optical discs)
It is widely used as a means for recording a large amount of information.
Such an optical disc is composed of a disc-shaped information recording medium formed of a predetermined material, and reading or writing of information is performed by irradiating the surface of the disc rotating at high speed with laser light. Therefore, a compact disc device or a video disc device that reads or writes information from or onto an optical disc, or a magneto-optical disc device or a phase-change disc device, etc. (here, these devices are stored in an information recording medium A device for reading information or writing information on an information recording medium is generically referred to as an information storage device) having an objective lens support device for irradiating an optical disc with laser light.

This objective lens supporting device is provided with an objective lens for focusing laser light on an information recording / reproducing surface of an optical disc, and the objective lens is supported by a lens holder so as to face the optical disc surface. The surface of the optical disk is not perfectly flat, and the distance between the objective lens and the surface of the optical disk changes as the optical disk rotates due to mechanical errors in the drive system that rotates the optical disk. Therefore, in order to always correctly focus the laser light on the information recording / reproducing surface of the optical disc, according to the change of the distance,
Since it is necessary to correct the position of the objective lens, a conventional objective lens supporting device is provided with a lens holder driving device including a coil, a magnet, a yoke, and the like to control the distance.

An example of such a conventional objective lens supporting device is shown in FIG. For ease of explanation, X,
Cartesian coordinates consisting of Y and Z axes are set for the objective lens support device as shown in the figure. In each coordinate axis, the direction of the arrow of each of the X, Y, and Z axes in the figure is a positive direction. The objective lens support device 10 is composed of a base 8, a lens holder 3, an objective lens 1, a lens holder support member 4, and the like.

A fixed portion 5 having an optical passage portion 5a is attached to one end of the base 8, and each of the four lens holder support members 4 has an end surface on the lens holder 3 side of the fixed portion 5. It is fixed to. The lens holder 3 is attached to and supported by the other ends of the four lens holder support members 4. Therefore, the lens holder 3 can be displaced in the positive or negative direction of the Z axis and the Y axis.

As shown in the sectional view taken along the line AA of FIG. 8, the lens holder 3 has a circular optical passage hole 3a at the tip thereof, and the objective lens 1 is provided in the lens mounting recess 3x at the upper end of the optical passage hole 3a. It is installed. The lens holder 3 also has an optical passage hole 3a.
Has a rectangular through hole 3b in the rear (in the negative direction of the X-axis) of the lens holder 3 in the Z-axis direction and in the Y-direction.
Focus coil 2 for axial displacement
a and the tracking coil 2b are accommodated.

The base 8 includes two upright yokes 8a, 8a.
A magnet 6 is attached to the yoke 8a, and the focus coil 2a is attached to the lens holder 3 with the yoke 8a and the magnet 6 housed inside. In FIG. 7, the yokes 8a and 8b and the magnet 6 are omitted in order to facilitate understanding of the coil portion. On the other hand, the tracking coil 2b is arranged in front of the focus coil 2a (in the positive direction of the X axis), close to the objective lens 1, and fixed to the lens holder 3.

Each yoke 8a, 8b and magnet 6
And an appropriate gap is provided between the inner surface of the through hole 3b and the focus coil 2a and the tracking coil 2b. When the lens holder 3 is displaced, the yoke 8
It does not come into contact with a, 8b and the magnet 6.

The mirror 7 is arranged on the base 8 below the objective lens 1 (in the direction of the page on the Z axis). The inclined surface 7a forms an angle of about 45 degrees with respect to the base 8, and the laser light incident from the X-axis direction through the optical passage portion 5a of the fixed portion 5 is incident on the inclined surface 7a in the Z-axis direction. The optical path is changed in the positive direction, and the light enters the objective lens 1 in parallel with the Z axis that is the optical axis thereof. Above the objective lens 1 is an optical disc 1
2 is arranged such that its surface is perpendicular to the Z axis which is the optical axis of the objective lens 1.

During operation of the information storage device, the optical disk 1
2 is rotated at a high speed by a predetermined rotation driving device about a predetermined axis parallel to the Z axis, and the optical disk 12 is irradiated with laser light focused by the objective lens 1 to read information from the optical disk 12. Or optical disc 1
The information is written to No. 2.

In many cases, the information recording / reproducing surface of the optical disc is not completely flat as described above, and the rotary drive mechanism also has a mechanical error. Therefore, when the optical disc rotates, the distance between the objective lens 1 and the optical disc 12 changes, and the laser beam may not be well focused on the information recording / reproducing surface of the optical disc. Therefore, an appropriate current is supplied to the focus coil 2a to move the lens holder 3 to Z
The information recording / reproducing surface of the optical disc 12 is displaced in the positive or negative direction of the axis so as to be displaced so that the distance between the objective lens 1 and the information recording / reproducing surface of the optical disc 12 is always an appropriate constant distance. Is controlled.

Further, since the objective lens supporting device 10 accesses each track formed on the optical disk 12, the whole is moved in the positive or negative direction of the Y axis by a predetermined driving device. This will be described with reference to FIG. Although only the optical disk is shown in FIG. 8 for simplification, in actuality, as shown in FIG. 9, the optical disk 12 is housed in a predetermined cartridge 14 so as not to be damaged and to be free from dust and the like. Protected. The cartridge 14 has an access window 14a, which is generally rectangular in a plan view, on at least one surface thereof. Through this access window 14a, the optical disk 12 is exposed in a predetermined radial range B between the center and the peripheral portion. Reference numeral 12a is the peripheral portion of the optical disc 12, and the center portion of the optical disc 12 (not shown) is on the opposite side in the drawing.

The objective lens supporting device 10 is arranged so that the optical disk 12 can be irradiated with laser light through the access window 14a, but its position in the Z-axis direction is generally below the lower surface 14d of the cartridge 14. Target. That is, the upper end of the objective lens 1 which is the uppermost part of the objective lens supporting device 10 in the positive direction of the Z-axis is arranged at a position lower than the lower surface 14 d of the cartridge 14.

By the way, the information storage device using an optical disc as an information recording medium has been made smaller and thinner as audio equipment, video equipment, personal computers and the like have become smaller. Therefore, from the viewpoint of reducing the thickness of the information storage device, the objective lens support device 1
As for the position of 0 in the Z-axis direction, as shown in FIG. 9, it is advantageous that at least a part thereof is located above the lower surface 14d of the cartridge 14. With such an arrangement, the distance between the upper surface of the cartridge 14 and the lowermost end of the objective lens supporting device 10, that is, the lower surface of the base 8 can be further shortened.

On the other hand, in the objective lens supporting device 10, as shown in FIG. 9, the objective lens 1 is directed to the optical disc 12 side, and the major axis parallel to the X axis is the optical disc 12.
Are arranged so as to be orthogonal to the radial direction of.

Even when the objective lens support device 10 is arranged below the lower surface 14d of the cartridge 14, the information storage device can be thinned to some extent. However, particularly in the case of an objective lens supporting device used for a small optical disc such as a mini disc (MD), the objective lens supporting device has a shape as shown in FIG. 10, which causes various problems. First, as described above, the lens holder 300 is
In order to focus the laser light emitted from the objective lens 1 on the information recording / reproducing surface of the optical disk 12, it is moved within a certain range in the positive and negative directions of the Z axis. Further, when the objective lens supporting device 10 is assembled, the position adjustment is performed on the lens holder 300 in the Z-axis direction. Therefore, the distance F1 between the lower surface 14d of the cartridge 14 and the upper surface 300c of the lens holder 300, and the upper surface 8c of the base 8
As a distance F2 between the lens holder 3 and the lower surface 300d of the lens holder 3, it is necessary to ensure a certain value in consideration of the displacement of the lens holder 300 for the above-mentioned focusing and position adjustment. Therefore, the objective lens supporting device 10 must be thinned while securing such values as the distances F1 and F2, and the thickness D of the lens holder 300 becomes extremely thin.

As a result, the heights of the focus coil 2a and the tracking coil 2b cannot be set sufficiently, and it becomes difficult to obtain a sufficient driving force. Then, as the lens holder 300 becomes thinner, the rigidity becomes smaller, and the secondary resonance frequency lowers. When the secondary resonance frequency of the lens holder 300 becomes low, control for keeping the distance between the information recording / reproducing surface of the optical disc and the objective lens constant (focus servo control) or control for causing the converged laser light to follow the information track of the optical disc ( In (tracking servo control), the servo band becomes narrow, the servo control becomes incomplete, or the servo control becomes difficult. Further, when the thickness of the lens holder 300 becomes thin, the vertical distance between the lens holder supporting members 4 also becomes narrow, resulting in an unstable posture of the lens holder 300 and rolling of the lens holder 300. That is, in order to access a specific position on the optical disk 12, the lens holder 30 is moved when the objective lens supporting device 10 is moved in the Y-axis direction by a required distance and then stopped.
0 oscillates around the X axis because of inertia, but the amplitude and duration of this oscillation become large enough to cause a problem if the vertical interval of the lens holder support member 4 is narrow, and in the worst case. Will result in out of focus.

In recent years, the density of optical discs has been remarkably increased, and the NA (Numerical Ape) of the objective lens 1 is increased.
(rture) tends to be a large value. Therefore, the distance between the objective lens 1 and the optical disk 12 (Work
ing Distance) also becomes small, and the portion of the objective lens 1 of the lens holder 300 has a shape protruding upward as shown in FIG. This does not cause much problem when the thickness D of the lens holder 300 is sufficient, but in order to reduce the thickness, when the thickness D is thin as shown in FIG. Becomes difficult,
In particular, the posture may become unstable when the lens holder 300 is driven in the track direction (Y-axis direction).

Due to these problems, particularly in the case of an objective lens supporting device used for a small-sized optical disk such as a mini disk, as shown in FIG. 9, at least a part of the objective lens supporting device has a lower surface 14d of the cartridge 14. It is more advantageous to reduce the thickness of the information storage device by making it higher.

[0020]

Objective lens supporting device 1
0 is arranged as shown in FIG. 9, the objective lens supporting device 1
0 is driven by a predetermined driving device as described above,
It moves in the positive or negative direction of the Y axis within the range B of the window. In the figure, the position C at the left end is the position for accessing the track closest to the center of the optical disc 12, while the position D at the right end is the position for accessing the track closest to the peripheral portion 12a of the optical disc 12. This is the position when doing.

When the objective lens supporting device 10 is at the position C, the side portion 3f of the lens holder 3 and the side portion 5b of the fixed portion 5 and the edge 1 of the access window 14a close to the center of the disc.
4b and the side portion 3g of the lens holder 3 and the side portion 5c of the fixed portion 5 and the edge 14c of the access window 14a near the disk peripheral portion 12a when the objective lens supporting device 10 is at the position D. The interval δ2 between and must be equal to or greater than a certain value. That is, when a specific track on the optical disk 12 is accessed, not only the objective lens supporting device 10 is moved to the corresponding position but also the position of the objective lens 1 is set more accurately, so that the tracking coil 2b is suitable. A large current is applied to adjust the position of the lens holder 3 on the Y axis. As a result, the laser light that has passed through the objective lens 1 is transferred to the optical disk
It is precisely illuminated on the truck. On the other hand, each component of the objective lens supporting device 10 and the mounting position on the information storage device main body side naturally have dimensional errors, and therefore the position is adjusted when the device is assembled. Therefore, even if the lens holder 3 moves along with the tracking or the position adjustment is performed, the edges 14b and 14c of the cartridge 14 are
And the side portions 3f and 3g of the lens holder 3 and the side portions 5b and 5c of the fixed portion 5 must not collide with each other. And need to. In the case of an information recording medium having a relatively large shape, the access window 14a of the cartridge 14 is also sufficiently large, and it is relatively easy to secure the necessary intervals δ1 and δ2. However, in the case of a small information recording medium such as a mini disc (MD), the window shape is extremely small and the sufficient intervals δ1, δ
It is not always easy to secure 2. It is physically possible to widen the range B of the access window 14a of the cartridge 14, but since the size of the access window 14a is determined by the standard, it is basically impossible to make the window large. is there. Therefore, in order to make the intervals δ1 and δ2 sufficient, it is necessary to narrow the width of the objective lens supporting device 10 in the short axis direction (Y axis direction).

One method of narrowing the width of the objective lens supporting device 10 in the minor axis direction is to reduce the size of the entire objective lens supporting device as it is. However, the objective lens supporting device used for a small-sized information recording medium has already been downsized, and if it is further downsized, it becomes difficult to obtain the required performance in each part, and the dimensional error is sufficiently suppressed. Becomes difficult. On the other hand, when the width of the objective lens supporting device 10 is simply narrowed, the lens holder 3 becomes extremely thin at a part thereof, and the secondary resonance frequency is lowered as the rigidity is lowered. Servo control or tracking servo control may be adversely affected. Further, the distance between the lens holder support members 4 becomes too narrow with respect to the length of the lens holder support member 4, and as described above, the lens holder 3 is used when the track is accessed.
Rolling may occur.

Therefore, an object of the present invention is to provide an objective lens supporting device which enables the information storage device to be made thinner without impairing its performance.

[0024]

In order to achieve the above object, the present invention comprises at least a base member, a fixing portion arranged on the base member, a lens holder for holding an objective lens, and the lens holder. A lens holder supporting member attached to the fixed portion so as to be movable in the optical axis direction of the objective lens, and through the objective lens for reading information from the information recording medium or writing information to the information recording medium. In the objective lens supporting device of the information storage device, which allows light to enter the information recording medium, the lens holder has a width of an end portion on a side closer to the information recording medium and an end portion on a side far from the information recording medium. Characterized by being narrower than the width.

In the present invention, the width of the end of the fixed portion closer to the information recording medium is narrower than the width of the end far from the information recording medium, and the lens holder supporting member is A first and a second pair of elastic members, the first
One end of each of the elastic members of the second pair is attached to the lens holder and the other end of the elastic members is attached to the fixing portion, and the elastic members of the first pair are substantially parallel to each other at a predetermined interval. , Is arranged substantially parallel to the information recording medium at a position separated from the base member by a predetermined distance,
Each of the second pair of elastic members is substantially parallel to each other at a spacing wider than the predetermined spacing, and is substantially parallel to the information recording medium at a position separated from the base member by a distance shorter than the predetermined spacing. It is characterized by being arranged in parallel.

The present invention is also characterized in that the elastic member is a leaf spring. The present invention is also characterized in that the information recording medium is any one of a compact disc, a video disc, a magneto-optical disc, and a phase change type disc.

According to the present invention, in the lens holder, the width of the end portion (upper portion) on the side closer to the information recording medium is narrower than the width of the end portion (lower portion) on the side far from the information recording medium. Therefore, when the objective lens supporting device of the present invention is arranged with respect to the cartridge in which the information recording medium is housed, even if the upper part of the objective lens supporting device is arranged so as to enter the access window of the cartridge, With the lens support device closest to the edge of the access window, with the side of the lens holder,
The required space can easily be secured between the edge of the access window. Therefore, it becomes easy to arrange the objective lens supporting device such that the upper part thereof is inserted into the access window of the cartridge. Further, since the width of the lower portion of the lens holder is wide, the rigidity of the lens holder is maintained.

The lens holder is supported by the four lens holder supporting members, and the distance between the two lens holder supporting members supporting the lower portion of the lens holder is equal to the distance between the lens holder supporting members supporting the upper portion of the lens holder. In the wider objective lens supporting device of the present invention, the lens holder can be supported more stably by widening the distance between the two lens holder supporting members supporting the lower part of the lens holder.

[0029]

BEST MODE FOR CARRYING OUT THE INVENTION Next, embodiments of the present invention will be described. FIG. 1 is a perspective view showing an example of an objective lens support device of an information storage device according to the present invention. For ease of explanation, Cartesian coordinates composed of X, Y, and Z axes are set for the objective lens support device as shown in the figure. Each coordinate axis has a positive arrow direction and a negative arrow direction.

This objective lens supporting device 100 has the same structure as the above-mentioned objective lens supporting device 10, but differs in the shape of the lens holder 30 in particular.
The difference is that the width of the fixed portion is narrowed. FIG. 3 shows the lens holder 30 as viewed from the positive direction of the X axis.
As can be seen from the figure, a step portion 30h is formed on the side portion of the lens holder 30, and the end portion 30 on the side closer to the optical disk 12 is formed.
The width E of c is smaller than the width F of the end portion 30d on the side far from the optical disc 12. Further, the fixed portion 50 has the Y
The width in the axial direction is smaller than the width E of the upper portion of the lens holder 30 plus the movement amount of the lens holder 30 during tracking.

The objective lens supporting device 100 is constructed as follows by using the lens holder 30 and the fixing portion 50 as described above. The configuration of the objective lens support device 100 is basically the same as the objective lens support device 10 described with reference to FIGS. 7 and 8 as described above. That is,
A fixing portion 50 is provided at one end of the base 8, and the four lens holder supporting members 4 made of an elastic material have their respective end portions fixed to the end surface of the fixing portion 50 on the lens holder 30 side. The lens holder 30 is attached to and supported by the other ends of the four lens holder support members 4.

As shown in the sectional view taken along the line AA of FIG. 2, the lens holder 30 has a circular light passage hole 30a at the tip thereof.
The objective lens 1 is mounted in the lens mounting recess 30x at the upper end of the optical passage hole 30a. The lens holder 30 also has a rectangular through hole 30b penetrating in the Z-axis direction behind the optical passage hole 30a (in the negative direction of the X-axis). Focus coil 2 for displacing each in the positive or negative direction of the axis
a and the tracking coil 2b are accommodated.

The base 8 is composed of two upright yokes 8a, 8a.
The magnet 6 is attached to the yoke 8a, and the focus coil 2a is attached to the lens holder 30 with the yoke 8a and the magnet 6 housed inside. In addition, in FIG. 1, the yokes 8a and 8b and the magnet 6 are omitted for easy understanding of the coil portion. On the other hand, the tracking coil 2b is arranged in front of the focus coil 2a, near the objective lens 1 and fixed to the lens holder 30 in this embodiment.

Each yoke 8a, 8b and magnet 6
And an appropriate gap is provided between the inner surface of the through hole 3b and the focus coil 2a and the tracking coil 2b. When the lens holder 30 is displaced, the yoke 8
It does not come into contact with a, 8b and the magnet 6.

The mirror 7 is arranged below the objective lens 1 (in the negative direction of the Z axis) and on the base 8. Its slope 7
a forms an angle of about 45 degrees with the base 8,
The laser light that has entered from the X-axis direction through the optical passage portion 50a of the fixed portion 50 has its optical path changed to the Z-axis positive direction on the inclined surface 7a and enters the objective lens 1 in parallel with its optical axis. An optical disc 12 is arranged above the objective lens 1 with its surface perpendicular to the optical axis of the objective lens 1.

The objective lens supporting device 100 having such a structure is arranged in the cartridge containing the optical disk as shown in FIG. 4, as in the case of FIG. That is, in the objective lens supporting device 100, in the portion of the rectangular window 14a of the cartridge 14 in plan view, the direction is such that the objective lens 1 is directed toward the optical disc 12 side, and the major axis parallel to the X axis is the radial direction of the optical disc 12. Are arranged so as to be orthogonal to.

On the other hand, the position of the objective lens supporting device 100 in the Z-axis direction is set so that the step portion 30h of the lens holder 30 is below the lower surface 14d of the cartridge 14 and as close as possible to the lower surface 14d. Therefore, the narrow portion above the stepped portion 30h of the lens holder 30 is inside the access window 14a and substantially above the lower surface 14d of the cartridge, and below the stepped portion 30h of the lens holder 30.
The wide portion is below the lower surface 14d.

When the information storage device operates, the optical disc 1
2 is rotated at a high speed by a predetermined rotation driving device about a predetermined axis parallel to the Z axis, and the optical disk 12 is irradiated with laser light focused by the objective lens 1 to read information from the optical disk 12. Or optical disc 1
The information is written to No. 2.

Then, in order to access the tracks formed concentrically on the optical disk 12, the objective lens supporting device 100 is moved in the positive or negative direction of the Y axis by a predetermined driving device. In, the position C at the left end is the position of the objective lens supporting device 100 when the track closest to the center of the optical disc 12 is accessed, while the position D at the right end is closest to the peripheral portion 12 a of the optical disc 12. This is the position for accessing the track.

When the objective lens supporting device 100 is in the position C, the side portion 30f of the lens holder 30 and the fixed portion 5 are provided.
The distance δ1 between the side portion 50b of 0 and the edge 14b of the access window 14a close to the center of the disc, and the side portion 30f of the lens holder 30 and the side of the fixed portion 50 when the objective lens supporting device 10 is at the position D. The distance δ2 between the portion 50b and the edge 14c of the access window 14a near the disk peripheral portion 12a must be set to a certain value or more, as described above. However, in this embodiment, since the width of the upper portion of the lens holder 30 is narrow and the width of the fixed portion 50 is also narrow, it is extremely easy to secure such an interval. Further, the width of the lens holder 30 is not narrow as a whole, but only the upper portion is narrow and the lower portion is wide, so that the rigidity of the lens holder 30 is maintained. Therefore, the secondary resonance frequency of the lens holder 30 does not decrease, the focus servo control or the tracking servo control is not adversely affected, and the recording or reproducing of information on the disk 12 is not hindered. Therefore, by using the objective lens supporting device 100 of the present embodiment, even for a mini disk having a narrow access window 14a, as shown in FIG.
0, the upper part of which is the access window 14a of the cartridge 14.
The information storage device can be arranged so as to enter the inside, and the information storage device can be made thinner.

In this embodiment, the lens holder 30
Although the stepped portion 30h is formed in the lens holder 30 to make the width of the upper portion of the lens holder 30 narrower than the width of the lower portion, the stepped portion is not formed in this way, and the side portion of the lens holder 32 is inclined as shown in FIG. The upper end portion 3 of the lens holder 32 by
It is also possible to make the width E of 2c narrower than the width F of the lower end portion 32d. With such a shape, the effect of the above embodiment can be obtained, and the rolling of the lens holder 32 is prevented. can do.

Next, another embodiment of the present invention will be described with reference to FIG. This embodiment is different from the above embodiment in that the lens holder supporting member 4 is arranged and that the fixing portion 50 is replaced with the fixing portion 52 as shown in FIG. FIGS. 6A and 6B are front views showing the lens holder 30 and the fixing portion 52 viewed from the X-axis direction. In the present embodiment, the fixing portion 52 has a step portion 52d on the side portion, like the lens holder 30, and the width E ′ of the upper portion of the fixing portion 52 in the Y-axis direction is the width E of the upper portion of the lens holder 30.
Is smaller than the value obtained by adding the movement amount of the lens holder 30 during tracking, and the width F of the lower portion is substantially the same as the width of the lower portion of the lens holder 30.

In this embodiment, the lens holder 3
0 and the distance between the two lens holder supporting members 4 attached to the lower portion of the fixed portion 52 are wider than the distance between the two lens holder supporting members 4 attached to the upper portion. Therefore, the support of the lens holder 30 by the lower two lens holder support members 4 becomes more stable in the attitude during the driving in the tracking direction (Y-axis direction) than in the case of the above-described embodiment, and the lens holder 30 is supported. Rolling can be prevented. Such arrangement of the lens holder support member 4 is shown in FIG.
Of course, the present invention can be applied to the lens holder 32 shown in FIG. 6, and in that case, the shape of the fixing portion should be the same as that of FIG. It may be inclined so that the width of the lower part is widened.

The objective lens supporting device 10 of this embodiment
In 0, two types of coils are used as described above, that is, the focus coil 2a and the tracking coil 2b,
Therefore, the objective lens 1 is configured to be displaced in two directions of the Y axis and the Z axis, but the number of coils required also changes if the number of directions in which the objective lens 1 is displaced changes. further,
A magnet is attached to the lens holder 30 side, and the base 8
Objective lens supporting device 100 of the type in which a coil is provided on the side
Also exists. And, as means for displacing the lens holder 30, other than using a coil and a magnet,
It is also possible to use a piezoelectric element or the like. However, none of these modifications are essential to the present invention and do not impair the effects of the present invention.

Further, in this embodiment, the fixed portion 50 is arranged in front of the mirror 7, but the fixed portion 50 is located on the opposite side of the lens holder 30 from the position shown in FIG.
It is also possible to support the lens holder 30 by arranging the lens holder support member 4 on the rear side of the lens holder 30 and attaching one end of the lens holder supporting member 4 to the fixing portion 5 and the other end to the lens holder 30 at that position. Even in such a configuration, the present invention is of course effective.

Further, the present invention can be applied to various information storage devices for optically reading or writing information such as compact discs, video discs, magneto-optical discs and phase change discs.

[0047]

As described above, in the objective lens supporting device of the information storage device of the present invention, the lens holder has a width of the end portion (upper part) on the side closer to the information recording medium than on the side far from the information recording medium. It is narrower than the width of the end (lower part). Therefore, when the objective lens supporting device of the present invention is arranged with respect to the cartridge in which the information recording medium is housed, even if the upper part of the objective lens supporting device is arranged so as to enter the access window of the cartridge, With the lens support device closest to the edge of the access window, with the side of the lens holder,
The required space can easily be secured between the edge of the access window. Therefore, it becomes easy to dispose the objective lens supporting device with its upper part intruding into the access window of the cartridge, and as a result, it is possible to reduce the thickness of the information storage device. Since the width of the lower portion of the lens holder is wide, the rigidity of the lens holder does not decrease and the secondary resonance can be kept high. Therefore, both focusing and tracking are controlled up to a sufficient frequency band, and there is no problem in recording or reproducing information on the information recording medium.

Furthermore, the distance between the two lens holder supporting members that support the lens holder by the four lens holder supporting members and the lower portion of the lens holder is equal to the distance between the lens holder supporting members that support the upper portion of the lens holder. In the wider objective lens supporting device of the present invention, the lens holder can be supported more stably by widening the distance between the two lens holder supporting members supporting the lower part of the lens holder, and the rolling of the lens holder can be performed. Can be prevented.

[Brief description of drawings]

FIG. 1 is a perspective view showing an example of an objective lens support device of an information storage device of the present invention.

2 is a partial cross-sectional side view showing the objective lens support device of FIG. 1. FIG.

FIG. 3 is a front view showing a lens holder that constitutes the objective lens supporting device of FIG.

FIG. 4 is a side view showing a state in which the objective lens supporting device of FIG. 1 is arranged with respect to a cartridge of an optical disc.

FIG. 5 is a front view showing another example of the lens holder that constitutes the objective lens support device of the present invention.

FIG. 6A is a front view showing a lens holder that constitutes an objective lens supporting device of the present invention, and FIG. 6B is a front view showing a fixing portion.

FIG. 7 is a perspective view showing an objective lens support device of a conventional information storage device.

8 is a partial cross-sectional side view showing the objective lens support device of FIG. 7. FIG.

9 is a side view showing a state in which the objective lens supporting device of FIG. 7 is arranged with respect to a cartridge of an optical disc.

FIG. 10 is a side view showing a state in which another conventional objective lens support device is arranged with respect to an optical disk cartridge.

[Explanation of symbols]

 1 Objective Lens 2a Focus Coil 2b Tracking Coil 3, 30, 32, 300 Lens Holder 3a, 30a Optical Passage Hole 3b, 30b Through Hole 4 Lens Holder Supporting Member 5, 50, 52 Fixing Part 5a, 50a Optical Passage Part 6 Magnet 7 Mirror 7a Inclined surface 8 Base 8a, 8b Yoke 10, 100 Objective lens support device 12 Optical disk 14 Cartridge 14a Access window

Claims (4)

[Claims] 1. A base member, a fixing portion arranged on the base member, a lens holder for holding an objective lens, the lens holder, and the fixing member movably in at least an optical axis direction of the objective lens. A lens holder supporting member to be attached to the information recording medium; and an objective of an information storage device that allows light to enter the information recording medium through the objective lens in order to read information from the information recording medium or write information to the information recording medium. In the lens supporting device, the lens holder has an end portion on a side closer to the information recording medium having a width narrower than an end portion on a side far from the information recording medium. Support device. 2. A width of an end portion of the fixed portion closer to the information recording medium is narrower than a width of an end portion of the fixed portion farther from the information recording medium, and the lens holder supporting member includes a first and a second portion. The elastic member of the first pair and the elastic member of the second pair are attached to the lens holder at one end and to the fixing portion at the other end, respectively. Are arranged substantially parallel to each other at a predetermined interval, and substantially parallel to the information recording medium at a position separated from the base member by a predetermined distance, and each of the second pair of elastic members is 2. The information recording medium according to claim 1, wherein the information recording medium and the information recording medium are arranged substantially parallel to each other at a distance wider than the predetermined distance and at a position separated from the base member by a distance shorter than the predetermined distance. Objective lens support for information storage device Place. 3. The objective lens support device of the information storage device according to claim 2, wherein the elastic member is a leaf spring. 4. The objective lens support device of the information storage device according to claim 1, wherein the information recording medium is one of a compact disc, a video disc, a magneto-optical disc, and a phase change type disc.