Objective lens drive apparatus with objective lens portion movable along support member axial direction

An objective lens drive apparatus includes a stationary member, a movable portion having an objective lens, an objective-lens holding member, and driving coils, and a plurality of rod-like elastic support members each having an axial direction parallel to a third direction perpendicular to a first direction and a second direction, the support members elastically supporting the movable portion so that the movable portion is movable to the stationary member in the first direction and the second direction. The movable portion is supported by the support members on both sides of the movable portion in the third direction, the support members are arranged on different planes perpendicular to the first direction, and the movable portion is arranged to be movable in the third direction with the support members, so that the objective lens is rotatable around an axis of the second direction.

BACKGROUND OF THE INVENTION

1. Surface of the Invention

The present invention relates to an objective lens drive apparatus provided to focus a light beam from an objective lens onto an optical disk as a light spot in order to perform recording/reproduction of the optical disk, and relates to an optical pickup device incorporating the objective lens drive apparatus, and an optical disk drive incorporating the optical pickup device.

2. Description of the Related Art

Conventionally, in the optical disk drive, the laser light beam, output from the laser light source, is focused with the objective lens on the optical disk as a light spot, and information is read from the optical disk by carrying out the opto-electric conversion of the reflected light from the optical disk.

The objective lens drive apparatus, which is provided in the optical disk drive, drives the objective lens in the focusing direction and the tracking direction using the control signal obtained from the reflected light, and causes the proper light spot to be formed on the recording surface of the optical disk by controlling the movement of the objective lens to follow the motion of the surface inclination of the optical disk or the eccentricity thereof.

In recent years, with the trend of high-density information recording, there is the demand to form the small light spot on the optical disk. To realize this, it is necessary to enlarge the NA (numerical aperture) of the objective lens or to shorten the wavelength of laser.

However, if the NA is enlarged or the wavelength of laser is shortened, the perpendicularity of the optical axis of the objective lens to the optical disk is shifted, and the coma aberration will easily be generated and the quality of the light spot will deteriorate. This causes the quality of recording/reproduction to deteriorate.

In order to attain high-density information recording, it is necessary to raise the inclination accuracy between the optical disk and the objective lens.

On the other hand, when processing mass data with the trend of high-density information recording, the improvement of the speed of recording/reproduction is desired, and it is necessary to carry out high-speed rotation of the optical disk.

When the high-speed rotation of the optical disk with which the surface inclination or the eccentricity exists is carried out, the accelaration becomes very large. In order to make the objective lens follow the optical disk with sufficient accuracy, the objective lens drive apparatus that is capable of generating a large force is needed.

There are some conceivable methods to correct the inclination between the optical disk and the objective lens. One of such methods is to make the movable portion of the objective lens drive apparatus containing the optical disk follow the inclination of the optical disk. This method will provide the high-speed capability to follow the rotational speed of the optical disk, with low cost.

For example, in the case of the method, consideration is given to incline the movable portion of the objective lens drive apparatus in the radial direction and the tangential direction. To realize this, the mechanism to drive the movable portion in the four axial directions, including the focusing direction and the tracking direction, is needed for the objective lens drive apparatus. In the objective lens drive apparatus with the multi-axial direction driving mechanism, the support rigidity will be made small so that it may be easy to carry out movement at least in a desired driving direction. This will easily affect the driving of the objective lens drive apparatus in the other directions.

For this reason, the cross talk generated between the driving axes becomes large, and it will not be negligible. The main cross talk which will not be negligible is as follows: (1) the cross talk of the radial and tangential rotation directions which is generated by the focusing and tracking movement drive; (2) the cross talk of the tracking movement direction which is generated by the radial movement drive; (3) the cross talk of the tangential rotation direction which is generated by the focusing movement drive; (4) the cross talk of the tangential movement direction which is generated by the focusing and tracking movement drive; and (5) the cross talk of the tangential movement direction which is generated by the tangential rotation drive.

Japanese Laid-Open Patent Application No. 10-275354discloses the objective lens drive apparatus which is configured to reduce the cross talk.FIG. 34shows such a conventional objective lens drive apparatus.

As shown inFIG. 34, a pair of support members101and102which have the same structure are arranged on the plane105which is perpendicular to the optical axis of the objective lens104. The ends101aand102aof the support members101and102are fixed to the side surfaces of the lens holder106, respectively. The other ends101band102bof the support members101and102are fixed to the stationary portion107.

The support member101is composed of the first rod-like member108extending from the stationary portion107and the second rod-like member110extending from the lens holder106and being at right angles the end of the first rod-like member108. The support member102is composed of the first rod-like member109extending from the lens holder106and the second rod-like member111extending from the lens holder106and being at right angles to the end of the first rod-like member109.

The rigidity of the objective lens104in the tangential rotation direction is set such that the rigidity on the side of the ends101a,102aof the support members101,102is smaller than the rigidity on the side of the other ends101b,102bof the support members101,102.

The drive magnets112and113are fixed to the lens holder106. The drive coils114and115(the focusing coil, the tracking coil, the radial drive coil and the tangential drive coil) are provided on the stationary portion107. By supplying electric current to the drive colis114and115respectively, the lens holder106including the objective lens104is driven in the four axial directions.

With such composition of the conventional objective lens drive apparatus, it is possible to form the movable portion into a thin structure and it is possible to provide the design in which the objective-lens principal point, the center of inertia of the movable portion and are made to be in proximity. It is possible for the conventional objective lens drive apparatus to reduce the cross talk of the tangential rotation direction which is generated when driving the lens holder106in the focusing direction.

However, in the conventional technique of Japanese Laid-Open Patent Application No. 10-275354, it is difficult to manage the rotation rigidity in the tangential tilt direction of the attachment section of the rod-like members108,109on the side of the lens holder106with the composition of the conventional objective lens drive apparatus ofFIG. 34.

Furthermore, the lens holder is supported with the rod-like members108and109. When it is configured by using the moving coil method, the wiring of the current to the lens holder106will run short. The conventional objective lens drive apparatus ofFIG. 34is applicable only by using the moving magnet method.

The mass of the movable portion increases when the moving magnet method is used since the magnet is provided on the side of the movable portion including the lens holder106. The acceleration sensibility becomes small, and it is difficult to follow the optical disk which is rotated at high speed.

When the moving coil method is used, the density of the magnetic fluxs passing through the coil can be increased by enlarging the magnet in order to make sensibility increase. However, when the moving magnet method is used, it is difficult to make sensibility increase since the mass of the movable portion increases when the magnet is enlarged. It is difficult to ensure adequate level of the acceleration which can follow the surface inclination or eccentricity of the optical disk.

With the composition of the conventional objective lens drive apparatus of Japanese Laid-Open Patent Application No. 10-275354, the movable portion is configured into a thin structure, and the magnitude of the mechanical components cannot be secured enough and there is the problem that the output acceleration is low.

Structurally, the focusing operation and the tangential tilt operation tend to influence mutually, and the occurrence of the tangential tilt is caused by the focusing operation. There is also the problem that the servo control becomes unstable.

Japanese Patent No. 3029616 discloses another objective lens drive apparatus.FIG. 35shows the composition of the main part of the conventional objective lens drive apparatus of Japanese Patent No. 3029616.

In the composition ofFIG. 35, the movable portion122containing the objective lens121is supported by the ends of the four rod-like elastic support members123–126(two pieces on one side) which are substantially in parallel. By using the electromagnetic drive unit (not shown), the objective lens121can be driven in the focusing direction, the tracking direction, the radial tilt direction and the tangential tilt direction as indicated by the arrows P1and P2inFIG. 35.

The other ends of the rod-like elastic support members123–126are independently fixed to the elastic arm129. The elastic arm129is provided so that it is rotatable around one of the axis127and the axis128, which are parallel to the tracking direction, in the directions indicated by the arrows M1and M2inFIG. 35.

With the composition ofFIG. 35, it is possible for the objective lens drive apparatus of Japanese Patent No. 3029616 to reduce the cross talk of the tangential tilt direction generated when the movable portion122is driven in the focusing direction.

However, in the conventional objective lens drive apparatus ofFIG. 35, the composition of movable parts129and130on the side of the stationary portion are complicated, and the elastic properties are not stabilized. Similar to the composition ofFIG. 34, in order to deal with the tilt compensation, the four rod-like elastic support members123–126are needed, and the wiring of current supply will run short. Hence, the composition ofFIG. 35is applicable only by using the moving magnet method. There is the problem that is the same as that of the composition ofFIG. 34.

In addition, Japanese Utility Model No. 2579715 and Japanese Laid-Open Patent Application No. 6-162540 disclose the objective lens drive apparatus in which the movable portion containing the objective lens is supported by the plurality of rod-like elastic-support members. With such composition, the movability and the stability of the support are improved.

However, in the composition of Japanese Utility Model No. 2579715 or Japanese Laid-Open Patent Application No. 6-162540, when the movable portion containing the objective lens is diren in one direction, the movement of the objective lens in the other directions becomes unstable or the movement is impossible.

Moreover, Japanese Published Utility Model Application No. 5-4096 and Japanese Laid-Open Patent Application No. 11-316963 disclose the objective lens drive apparatus in which the end of the rod-like elastic support member on the side of the stationary portion is fixed to the reaf spring member.

In the composition of Japanese Published Utility Model Application No. 5-4096 or Japanese Laid-Open Patent Application No. 11-316963, the direction in which the objective lens can stably be driven is restricted to a specific direction, and the position of the light spot on the optical disk is changed when the objective lens is driven in the direction.

SUMMARY OF THE INVENTION

An object of the present invention is to provide an improved objective lens drive apparatus in which the above-described problems are eliminated.

Another object of the present invention is to provide an objective lens drive apparatus which can drive the objective lens with sufficient accuracy at high speed.

Another object of the present invention is to provide an optical pickup device that is appropriate for use with an objective lens drive apparatus so that the objective lens drive apparatus can drive the objective lens with sufficient accuracy at high speed.

Another object of the present invention is to provide an optical disk drive that is appropriate for use with an optical pickup device and stably carries out accessing of an optical disk with the optical pickup device with sufficient accuracy at high speed.

The above-mentioned objects of the present invention are achieved by an objective lens drive apparatus comprising: a stationary member; a movable portion having an objective lens, an objective-lens holding member holding the objective lens, and driving coils or magnets generating a first force in a first direction parallel to an optical axis of the objective lens and a second force in a second direction perpendicular to the optical axis of the objective lens; and a plurality of rod-like elastic support members each having an axial direction parallel to a third direction perpendicular to both the first direction and the second direction, the support members elastically supporting the movable portion so that the movable portion is movable to the stationary member in the first direction and the second direction, wherein the movable portion is supported by the support members on both sides of the movable portion in the third direction, the support members are arranged on different planes perpendicular to the first direction, and the movable portion is arranged to be movable in the third direction with the support members, so that the objective lens is rotatable around an axis of the second direction.

The above-mentioned objects of the present invention are achieved by an objective lens drive apparatus comprising: a stationary member; a movable portion having an objective lens, an objective-lens holding member holding the objective lens, and driving coils or magnets; and a plurality of rod-like elastic support members provided between the stationary member and the movable portion, each support member having an axial direction that is parallel to a third direction perpendicular to both a first direction and a second direction, the support members elastically supporting the movable portion to be movable to the stationary member, wherein the movable portion is supported by the support members on both sides of the movable portion, and the support members are arranged on a single plane perpendicular to the first direction and in the third direction symmetrically with respect to an optical axis of the objective lens.

The above-mentioned objects of the present invention are achieved by an objective lens drive apparatus comprising: a stationary member; a movable portion having an objective lens, an objective-lens holding member holding the objective lens, and driving coils or magnets; and a plurality of rod-like elastic support members provided between the stationary member and the movable portion, each support member having an axial direction that is parallel to a third direction perpendicular to both a first direction and a second direction, the support members being arranged in the first direction apart from each other and elastically supporting the movable portion to be movable to the stationary member at least in a tilt direction of the third direction, wherein the movable portion is supported by the support members on both sides of the movable portion, and the support members are arranged on a single plane perpendicular to the first direction and in the third direction symmetrically with respect to an optical axis of the objective lens, the end on the side of the stationary member which supported the movable portion by the support members from both sides in the third direction, and is estranged in the first direction in the support member, it is fixed to the part from which the radius of gyration on the elastic board which the width of face of the focusing direction is formed narrowly partially, respectively, and rotates the shaft of the tracking direction as a center differs, the objective lens drive apparatus is configured so that the elastic board is rotatable corresponding to tangential tilt operation of the movable portion.

The above-mentioned objects of the present invention are achieved by an optical pickup device comprising: an objective lens drive apparatus; a laser light source outputting a laser light beam to an optical disk; a light-receiving optical unit receiving a reflected light beam from the optical disk; and an objective-lens control unit outputting a control signal to the objective lens drive apparatus based on the reflected light beam received by the light-receiving optical unit, the objective lens drive apparatus comprising: a stationary member; a movable portion having an objective lens, an objective-lens holding member holding the objective lens, and driving coils or magnets generating a first force in a first direction parallel to an optical axis of the objective lens and a second force in a second direction perpendicular to the optical axis of the objective lens; and a plurality of rod-like elastic support members each having an axial direction parallel to a third direction perpendicular to both the first direction and the second direction, the support members elastically supporting the movable portion so that the movable portion is movable to the stationary member in the first direction and the second direction, wherein the movable portion is supported by the support members on both sides of the movable portion in the third direction, the support members are arranged on different planes perpendicular to the first direction, and the movable portion is arranged to be movable in the third direction with the support members, so that the objective lens is rotatable around an axis of the second direction.

The above-mentioned objects of the present invention are achieved by an optical disk drive in which an optical pickup device, a rotation drive unit controlling rotation of an optical disk, and a pickup drive unit moving the optical pickup device in a radial direction of the optical disk, the optical pickup device comprising: an objective lens drive apparatus; a laser light source outputting a laser light beam to the optical disk; a light-receiving optical unit receiving a reflected light beam from the optical disk; and an objective-lens control unit outputting a control signal to the objective lens drive apparatus based on the reflected light beam received by the light-receiving optical unit, the objective lens drive apparatus comprising: a stationary member; a movable portion having an objective lens, an objective-lens holding member holding the objective lens, and driving coils or magnets generating a first force in a first direction parallel to an optical axis of the objective lens and a second force in a second direction perpendicular to the optical axis of the objective lens; and a plurality of rod-like elastic support members each having an axial direction parallel to a third direction perpendicular to both the first direction and the second direction, the support members elastically supporting the movable portion so that the movable portion is movable to the stationary member in the first direction and the second direction, wherein the movable portion is supported by the support members on both sides of the movable portion in the third direction, the support members are arranged on different planes perpendicular to the first direction, and the movable portion is arranged to be movable in the third direction with the support members, so that the objective lens is rotatable around an axis of the second direction.

According to the objective lens drive apparatus of the present invention, it is possible to correct the inclination error of the optical disk and the objective lens. By making it possible to generate the driving force which can follow the optical disk under high-speed rotation to carry out the independent drive at each shaft orientations, the movability of the tangential tilt direction can be made good, and the sensibility can be made small.

The optical disk drive of the present invention can perform stable control and it sets to the objective lens drive apparatus dealing with inclination compensation. The cross talk between the drive shafts which are easy to pose the problem can be reduced. Specifically, it is possible to reduce the cross talk including the cross talk of the tangential rotation direction generated by focusing translation drive, the cross talk of the tangential movement direction generated by focusing or tracking translation drive, and the cross talk of the tangential movement direction generated by the tangential rotation drive.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

A description will now be provided of the preferred embodiments of the present invention with reference to the accompanying drawings.

FIG. 1shows the objective lens drive apparatus of one preferred embodiment of the present invention.FIG. 2is a front FIG. of the objective lens drive apparatus ofFIG. 1.

InFIG. 1andFIG. 2, reference numeral1indicates the objective lens, and reference numeral2indicates the objective-lens holding member which forms a movable portion in which the objective lens1is mounted at the central upper part of the movable portion. The focusing coils3(only two pieces on one side are shown) are held on the objective-lens holding member2.

In the objective lens drive apparatus ofFIG. 1, the tracking coils4aand4bare held on the objective-lens holding member2. The plural wire springs5a–5dform the rod-like elastic supporting member which holds the objective-lens holding member. The wire springs5a–5dserve as the movable-portion supporting member which supports the movable portion. In the present embodiment, the eight wire springs5a–5dare provided, and the four of them are provided on one side of the tangential direction, and the remaining four are provided on the other side (but they are not shown).

The objective lens drive apparatus ofFIG. 1includes the stationary members6, the base member7, the magnets8, the yoke portions9and the elastic boards10. The magnets8are arranged on the inside walls of the stationary members6so that they are opposed to the focusing coils3and the tracking coils4aand4b. Each of the elastic boards10is formed by a flexible circuit board.

InFIG. 1andFIG. 2, the objective-lens holding member2which holds the objective lens1is elastically supported by the eight wire wprings5a–5dat the support projections2aand2bwhich project from the holding member2in the opposing directions. The axial directions of the wire springs5a–5dare parallel to the tangential direction which is perpendicular to both the focusing direction and the tracking direction. The four of the wire springs5a–5dare arranged on one side of the tangential direction of the optical disk which is a recording/reproduction medium, and the remaining four are arranged on the opposite side of the tangential direction. The eight wire springs in total are arranged in parallel and at the symmetrical positions on the two surfaces that are perpendicular to the focusing direction.

The four focusing coils3and the two tracking coils4aand4bare attached to the corners of the objective-lens holding member2. The objective-lens holding member2with the focusing coils3and the tracking coils4aand4battached serves as the movable portion to the stationary members6.

The wire springs5a–5dare made of a conductive substance, and the ends of the wire springs5a–5dare secured to the elastic board10by soldering. The wire springs5a–5dserve as the current supply members which respectively supply the current to the drive coils3,4a,4bfrom the ends of the wire springs5a–5don the side of the stationary members6.

The elastic boards10are formed by flexible circuit boards. The flexible circuit boards10are provided with the wiring that is used to supply the current to the drive coils (the focusing coil3and the tracking coils4aand4b) through the wire springs5a–5d.

As shown inFIG. 1, the focusing direction is parallel to the direction of the optical axis of the objective lens1and corresponds to the first direction in the claims. The tracking direction is perpendicular to the direction of the optical axis of the objective lens1and corresponds to the second direction in the claims. The tangential direction is perpendicular to both the focusing direction and the tracking direction and parallel to the axial directions of the wire springs5a–5d, and corresponds to the third direction in the claims.

The portions of the elastic boards10to which the wire spring ends are secured are arranged so that the wire springs5a–5dare displaceable in the axial directions of the wire springs (which are parallel to the tangential direction). The elastic boards10are attached to the stationary members6which are fixed to the base member7.

The base member7is the magnetic substance and forms the yoke section9by bending the part. The magnetic circuit is formed so that the magnetic flux may pierce in each drive coil with the magnet8fixed to this yoke section9.

It is possible to drive the movable portion to the focusing direction, the radial tilt direction, and the tangential direction by attaching four focusing coils3in the four corners of the objective-lens holding member2, and adjusting the current passed in each focusing coil3.

Moreover, by passing the current in the tracking coils4aand4b, it is possible to drive the movable portion containing the objective-lens holding member2to the tracking direction, the face deflection in the optical disk which rotates at high speed, eccentricity, the curvature, etc. can be followed, and it is possible to form the good light spot in the optical disk side.

When it is going to drive the objective lens1only to the focusing direction, by making four focusing coils3generate equivalent driving force, the driving force to the focusing direction occurs at the center in the objective-lens holding member2.

On the other hand, since the part which differs from the driving force generating part with the wire springs5a–5dto the stationary members6is supported, the moment will generate the objective-lens holding member2by the difference in the position of the driving point and the supporting point.

However, since the objective-lens holding member2in the present embodiment is the symmetrical configuration as a center, and are the both sides of the tangential direction and the optical axis of the objective lens1is supported in the equivalent distance, the moment which occurred on both sides of the tangential direction will be canceled mutually.

Therefore, even if it makes small rotation rigidity (or rigidity in the tangential movement direction) in the tangential direction in order to carry out tilt compensation since the moment will not occur in the objective-lens holding member2as a whole, it does not rotate to the tangential direction.

In the present embodiment, the cross talk of the tangential direction generated by focusing translation drive can be reduced.

Moreover, with the composition which makes rotation rigidity in the tangential direction small, since it is what makes small rigidity in the shaft orientations of the wire spring, it becomes easy to generate the optical-axis gap in the tangential movement direction.

Moreover, since the wire spring is bent by the usual wire support method when the objective-lens holding member is moved to the focusing direction or the tracking direction, it will become short to shaft orientations and the objective lens will move to the tangential direction.

However, in the present embodiment, since the objective-lens holding member2is supported on tangential-direction both sides and rigidity (spring modulus of each part) is also set up equally, it is possible for the force of shaft orientations (tangential direction) when the objective-lens holding member2moves to the focusing direction or the tracking direction to balance, and to suppress movement to the tangential direction of the objective lens1.

In the present embodiment, the cross talk of the tangential movement direction generated by focusing translation drive can be reduced.

FIG. 3is a perspective view of the objective lens drive apparatus of another preferred embodiment of the present invention.FIG. 4is a front view of the objective lens drive apparatus ofFIG. 3.

InFIG. 3andFIG. 4, the elements which are essentially the same as corresponding elements inFIG. 1are designated by the same reference numerals, and a description thereof will be omitted.

In the objective lens drive apparatus to which tilt compensation is performed, the cross talk of the tangential movement direction occurs also by carrying out the tangential-tilt drive.

This will be generated when the center of rotation in the tangential direction is distant from the principal point of the objective lens.

In the preferred embodiment ofFIG. 3, in order to carry out the center of rotation in the tangential direction near the principal point of the objective lens1, the previous embodiment is modified and and the following composition is adopted.

InFIG. 3andFIG. 4, the wire springs5a–5dare opposed to the focusing direction (the direction of the optical axis of the objective lens1) on two perpendicular virtual planes.

The elastic board1to which the edge of the wire springs5aand5barranged considering the tangential direction as a lengthening joint, constitutes one of the two virtual surfaces in which the wire springs5a–5dare arranged so that the principal point M of the objective lens1may be included, and are arranged in the virtual plane is fixed.

It is set up so that rigidity of the tangential direction may be enlarged (or it sets up so that it may become the rigid body).

It is made to specifically regulate the motion of the elastic board10by the stationary members6like the section shown inFIG. 3.

Moreover, it sets up so that rigidity of the tangential direction of the elastic board to which the wire springs5cand5darranged to the virtual side of another side are fixed may be made small.

When the driving force of the tangential direction occurs in the objective-lens holding member2, it is possible to carry out the tilt at the center of the principal point M of the objective lens1.

In the present embodiment, the cross talk of the tangential movement direction generated by the tangential rotation drive can be reduced.

The direction made to extend to near the optical axis of the objective lens1as much as possible tends to carry out the tilt drive of the fixed end on the side of the wire springs5a–5dat the projections2aand2bof the objective-lens holding member2.

It is also possible to suppress the occurrence of the cross talk of the tangential tilt generated by the focusing movement and the tangential movement direction by supporting the both sides of the tangential direction symmetrically to the objective-lens holding member2.

In the above-mentioned embodiments, it is possible to support the rotation of the objective-lens holding member2by fixing the fixed-end section on the side of the stationary member6in the wire springs5a–5dto the elastic boards10which can be displaced to the tangential direction.

In order to give elasticity to the tangential movement direction, it is possible to form the wire spring as follows.

FIG. 5shows the main part of the objective lens drive apparatus of another preferred embodiment of the present invention.

In the present embodiment, the end on the side of the stationary members6in the wire springs5a–5din the preferred embodiment 1 is fixed to the stationary members6which does not move to the tangnetial axis direction.

As the wire springs5′a–5′d, the flat spring formed of not the rounded wire but etching processing or fine-punching processing of the lamina sheet metal is used, and it is the bending bent portion1about the middle of wire springs5′a–5′d.

The objective-lens holding member2is supported in elasticity to the tangnetial axis direction by forming1and forming the part which is easy to bend in the tangential direction.

The other composition of the present embodiment is the same as the composition of the previous embodiment.

Since it is unnecessary to attach to the elastic boards10by giving the elasticity of the tangential direction to the wire springs5′a–5′dwhich include the flat spring, the attaching operation can be made easy.

FIG. 6shows the main part of the objective lens drive apparatus of another preferred embodiment of the present invention.

The end on the side of the stationary members6in the wire springs5a–5dis fixed to the stationary members6which does not move to the tangential direction. Moreover, the end on the side of the objective-lens holding member2in the wire springs5a–5d.

It attaches in the lobe12which is easy to bend in the tangential direction (the direction of the arrow head), and is formed in the objective-lens holding member2at it, or attaches in the flexible member (not shown) which is fixed to the objective-lens holding member2, and can bend in the tangential direction.

It becomes possible like the preferred embodiment 1 and the preferred embodiment 2 to support the objective-lens holding member2in elasticity to the tangnetial axis direction.

In addition, the composition of others in the preferred embodiment4is the same as the composition of the previous embodiment 1.

FIG. 7shows the objective lens drive apparatus of another preferred embodiment of the present invention.FIG. 8is a front FIG. of the objective lens drive apparatus ofFIG. 7.

In the present embodiment, a thin structure of the objective lens drive apparatus is attained by arranging the objective lens drive apparatus and the optical system in the same surface in the height direction.

In the present embodiment, the support composition of the objective-lens holding member2can adopt all of the composition of the preferred embodiments.

In the objective lens drive apparatus in which inclination compensation is possible, the objective-lens holding member2will be thinly formed in the focusing direction in order to locate the drive center and the center of inertia (center of gravity) near the principal point of the objective lens1, it is difficult to secure the driving force.

Although the driving force of the objective lens drive apparatus is generated by constituting so that the drive coil passes through the magnetic flux, when driving the two shafts of the focusing direction and the tracking direction at least, the direction of the magnetic flux arranges the magnet8in many cases so that the direction perpendicular to the tangential direction, may be generated.

For this reason, it is more efficient to arrange the front face (large surface) of the magnet8to the virtual flat surface and parallel which pass along both the shafts of the focusing direction and the tracking direction.

Moreover, although the layout which bends the laser light beam L which carries out incidence to the objective lens1using the starting mirror13which deflects the laser light beam L upwards in the lower part (the optical disk installation side and opposite side) of the objective lens1the 90 degrees is common in order to make equipment form thinly.

With the composition with which the thin structure is important and the magnetic circuit is arranged at the tangential-direction both sides in the objective-lens holding member2, in order that the magnetic-circuit part may interrupt the laser light beam L, it is not suitable.

Then, it is made composition which does not arrange the components to the one side of the objective lens1, and from the one side, incidence of the laser light beam L can be carried out, and the thin structure can be attained by arranging the objective lens drive apparatus and the optical system to the same surface.

However, in order for the high order resonance by the movable portion, such as the objective lens1and the objective-lens holding member2, carrying out the elastic deformation in the drive high frequency range by the objective lens drive apparatus of composition of supporting the objective lens1by the one side in this way to get worse and to degrade the servo property remarkably, it becomes difficult to make it follow with high precision at high speed.

That is, the direction which arranges the objective lens1at the center of the objective-lens holding member2, and arranges the magnetic circuit on both sides tends to secure the high order resonance property.

However, if this configuration is made thin, the superficial content of the magnetic circuit becomes small, and since the space of the drive coil arranged decreases, the problem will arise that it is hard to acquire large driving force.

Only the focusing coil3does not need to make the center of gravity of the objective-lens holding member2in agreement with the focusing direction in the drive coil.

Therefore, the magnetic circuit is formed in the focusing direction for a long time, the drive coil15as the tracking drive coil, the radial drive coil, and a tangential drive coil is arranged to the optical disk installation side, and it is the focusing coil in the optical disk installation side and the opposite side.

By arranging16, it is the focusing coil from the objective-lens holding member2.

Although16projects in the opposite side the optical disk installation side of the focusing direction, from the radial direction in the objective-lens holding member2, space will be vacant.

The optics portion of the objective lens drive apparatus can be arranged in the same surface in the focusing direction by turning up the 90 degrees to the optical disk installation side by the mirror13by carrying out incidence of the laser light beam L from the radial direction in this part, and rising in the part pinched by the lower part of the focusing coil16or the magnetic circuit. It is possible for the present embodiment to form the whole equipment thinly.

FIG. 9shows the objective lens drive apparatus of another preferred embodiment of the present invention.FIG. 10is a front view of the objective lens drive apparatus ofFIG. 9.

In the present embodiment, the modification of the previous preferred embodiment is the objective-lens holding member.

By taking a large width of the spacing of the support projections2aand2bnear the center of the objective-lens holding member2in the tangential direction for the wire springs5a–5d, it becomes possible to make the laser light beam L from the tracking direction to be incident to the spacing. By piling up a part of the optical system and the objective lens drive apparatus in the height direction, it is possible to make the height of the whole equipment small.

In the present embodiment, the configuration of the moving coil method is adopted. However, the present invention is also applicable even if it is the moving magnet method which installs the magnet in the objective-lens holding member as an electromagnetic drive unit.

FIG. 11shows the objective lens drive apparatus of another preferred embodiment of the present invention.FIG. 12shows the main part of the electromagnetic drive unit in the preferred embodiment ofFIG. 11.FIG. 13shows the objective-lens holding-member in the preferred embodiment ofFIG. 11.

In the present embodiment, the objective-lens holding member2holding the objective lens1is supported in elasticity by the rod-like flat spring17which is the rod-like elastic-support object which makes the tangential direction the lengthening joint.

The bent portion17ais formed in part, and the rod-like flat spring17is allotted on the one flat surface perpendicular to the focusing direction, and it totals it four on both sides of the tangential direction and the radial direction focusing on the optical axis of the objective lens1. Eight are arranged in parallel.

InFIG. 12andFIG. 13, the aspect of the tangential direction of the objective-lens holding member2is equipped with four types of drive coils including the first focusing coil3a, the second focusing coil3b, the tracking coil4between the focusing coils3a,3b, and the radial tilt coils18aand18bconnected to the focusing coils3aand3b, and the movable portion is thus constituted.

The base member7is made of the magnetic substance and forms the yoke section9by bending the part.

The driving magnet8fixed to the yoke section9is arranged at the both sides of the tangential direction in the objective-lens holding member2, and it is arranged so that the magnetic flux may pass through both the focusings coils3aand3b, the tracking coil4, and the radial tilt coils18aand18b, and the magnetic circuit is thus formed.

The divisional magnetization of the magnet8is carried out by the magnetization boundary line a of the focusing direction in the center of the tracking direction. The division magnetization of the both sides of the magnetization boundary line a is further carried out by the magnetization boundary line b of the focusing direction perpendicular to the end surface on the side of the optical disk installation in the magnet8, and the magnetization boundary line c perpendicular to the aspect of the tracking direction in the magnet8in the L-shaped formation.

The first focusing coil3aand second focusing coil3bare wound around the axis of the tangential direction, and they are arranged at the both sides in the tracking direction of the magnetization boundary line a of the magnet8.

The part to which the current flows to the two tracking directions of the focusing coils3aand3bis arranged at the both sides in the focusing direction of the magnetization boundary line c, respectively, and the part to which the current flows to the focusing direction is arranged ranging over the magnetization boundary line b.

The tangential direction is wound around the tracking coil4as a shaft, the magnet8is countered, and the part to which the current flows to the tracking direction is constituted ranging over the magnetization boundary line a.

The radial tilt coils18aand18bare wound around the axis of the tangential direction, and they are arranged at the both sides of the magnetization boundary line a.

It is constituted so that the part to which the current flows to the tracking direction on the side of optical disk installation ranges over the magnetization boundary line b of the magnet8, while the part to which the current flows to the focusing direction of the side far from the magnetization boundary line a ranges over the magnetization boundary line c of the magnet8.

The movable portion can be driven to the focusing direction by passing the equivalent current to the first focusing coil3aand the second focusing coil3b.

Moreover, driving to the tangential tilt direction is possible by giving the difference to the current passing through the first focal coil3aand the current passing through the second focusing coil3b.

Moreover, it can drive in each direction by passing the current through the tracking coil4and the radial tilt coils18aand18b.

The eight rod-like flat springs.17are manufactured by etching or precision sheet metal work, are setting thickness to about 50 micrometers, and as shown in the plan showing inFIG. 14, after they really cast the one plate-like member19by this example to the objective-lens holding member2and the stationary members6, they can form it by excising the unnecessary part by it.

By doing in this way, the positioning accuracy to the span between each rod-like flat spring17or the objective-lens holding member2, and the stationary members6improves, and it becomes possible further to also make small struggling between the individuals of the rod-like flat spring17.

While the movability improves by crookedness section17aprepared in a part of rod-like flat spring17, the deformation of the lengthening joint in the rod-like flat spring17at the time of operation can be absorbed, and struggling in primary resonance frequency or displacement sensibility can be reduced.

FIG. 15is a perspective view of the objective lens drive apparatus of another preferred embodiment of the present invention, andFIG. 16is a diagram showing the objective-lens holding member in the preferred embodiment ofFIG. 15. InFIG. 15andFIG. 16, the elements which are essentially the same as corresponding elements in the previous embodiment are designated by the same reference numerals, and a description thereof will be omitted.

In the present embodiment, apart from the previous embodiment, it is arranged so that it may become small (thinly) on the whole in the focusing direction, and the rod-like flat spring17is arranged on the flat surface near the principal-point A of the objective lens1.

Therefore, the support center will be arranged near the principal-point A of the objective lens1.

When the center of gravity of the movable portion is given the radial tilt driving force or tangential-tilt driving force to the movable portion by arranging it near the principal point A of the objective lens1, the rotation operation is performed on the center of the principal point A of the objective lens1.

Since the light spot on the optical disk focused with the objective lens1is not fluctuated to the tracking direction or the tangential direction, stable servo operation is attained.

FIG. 17shows the objective lens drive apparatus of another preferred embodiment of the present invention.FIG. 18is an enlarged view of the printed circuit board part of the objective-lens holding member in the embodiment ofFIG. 17.

The objective-lens holding member2holding the objective lens1is supported in elasticity in the preferred embodiment 9 with the wire springs5which makes the tangential direction the lengthening joint.

Four a total of eight are arranged in parallel by the both sides of the tangential direction and the radial direction focusing on the optical axis of the objective lens1on one flat surface with the wire springs5perpendicular to the focusing direction.

After arranging two wire springs5with the tangential direction for each of the both sides respectively and carrying out solder fixation of the one wire spring from the first at the movable portion and the stationary portion of the objective lens drive apparatus, it is possible by excising the unnecessary section to raise the positioning accuracy to the span or the objective-lens holding member2, and the stationary members6.

It is made for the edge of the tangential direction in the land of the printed circuit board20by which solder fixation is carried out and the wire spring5which adjoins further is being fixed to the land of the printed circuit board20arranged at right angles to the focusing direction in the radial-direction both sides of the objective-lens holding member2to be located in the same ridgeline R, as the fixed-end section on the side of the movable portion in eight wire springs5is as shown inFIG. 18.

Since the effective length in the wire spring5is decided in the board10of the stationary members6and the ridgeline R which fix the other edges of5, struggling in the die length of the wire spring5can be suppressed to the minimum.

The fixed-end section on the side of the stationary members6of the wire spring5may be made to carry out solder fixation at the elastic board21which has flexibility in the shaft orientations of the wire spring5, and is moved slightly to them, as shown inFIG. 19. It is possible to improve the movability by this composition.

Moreover, the printed circuit board20of the objective-lens holding member2is arranged in the objective lens1on both sides of the center of gravity G of the movable portion at the opposite side (lower part side), as shown inFIG. 20.

Usually, since the objective lens1with large mass is arranged at the optical disk installation side, the center of gravity G of the movable portion tends to approach the optical disk installation side.

Although it is necessary to attach the weight for the balancers in the lower part of the movable portion in order to make this center of gravity G in agreement with the support center and the drive center, in the present embodiment, by making the printed circuit board20serve a double purpose as a balancer, components mark are reduced and it makes it possible to reduce the weight of the movable portion.

The stationary member in the rod-like elastic member (the wire springs5,5a–5d, and the rod-like flat spring17) if it is in the objective lens drive apparatus of composition of supporting the movable portion by the spring member, in order to make the primary resonance detected from the support system and the moving-part mass property usually decrease.

The viscoelasticity ingredient is prepared in the end on the side of six in many cases.

Then, as shown in the perspective diagram showing the principal part of the objective lens drive apparatus for explaining the preferred embodiment ofFIG. 21, in order to make resonance of the tangential tilt direction fully decrease, the deformation of the wire spring5on the side of the movable portion has formed the viscoelasticity ingredient22in the large part, and the large damping effect is made to be acquired in the preferred embodiment.

In addition, if the viscoelasticity material22is formed also in the edge of the wire spring5on the side of the stationary members6, the damping effect will increase further.

FIG. 22shows the objective lens drive apparatus of another preferred embodiment of the of the present invention, andFIG. 23shows the electromagnetic drive unit in the objective lens drive apparatus ofFIG. 22.

As shown, the movable portion includes the objective-lens holding member2holding the objective lens1and the drive coil is supported in elasticity in the present embodiment with the wire spring5which makes the tangential direction the lengthening joint to the stationary portion.

The wire spring5is estranged to two in the focusing direction, and a total of eight are installed four symmetrically with each of the tangential direction and the radial direction focusing on the optical axis of the objective lens1.

As shown inFIG. 23, in the mechanical component, the both-sides aspect of the tangential direction of the objective-lens holding member2is equipped with the focusing coil3which is the flat-surface-like drive coil wound around the axis of the tangential direction, the tracking coil4, the radial tilt coil25, and the tangential-tilt coil26.

The focusing coil3, the radial tilt coil25, and the tangential-tilt coil26are isomorphism-like4ream coils, and each generates the thrust of the focusing direction.

However, it is made for the direction of the thrust to have differed by changing the polarity of the current which flows in each coil.

Namely, for all the four coils for which the focusing coil3passes the current the thrust is generated in the same direction and the movable portion is driven to the focusing direction.

The radial tilt coil25drives the movable portion to the radial tilt direction by generating the thrust of the opposite direction in the both sides in the tracking direction on both sides of the optical axis of the objective lens1.

Moreover, the tangential-tilt coil26is driven to the tangential-direction by generating the thrust of the opposite direction on both sides in the tangential direction on both sides of the optical axis of the objective lens1.

InFIG. 22, the base member7includes the magnetic substance, and forms the yoke section9by bending the part.

The magnet8for the drive fixed to this yoke section9is arranged in the both sides in the tangential direction of the objective-lens holding member2, and as shown inFIG. 23, the magnetic circuit is formed so that it may receive at right angles to the focusing coil3, the tracking coil4, the radial tilt coil25, and the tangential-tilt coil26and the magnetic flux may pierce.

The direction perpendicular to the surface which division magnetization of the magnet8is carried out by the magnetization boundary line a of the focusing direction, and the magnetization boundary line b of the tracking direction at the shape of a cross joint, and contains the focusing direction and the tracking direction, and it is magnetized in the opposite direction in the adjacent range.

Moreover, the drive coils3,4,25, and26can be arranged so that the magnetization boundary lines a and b may be straddled, and they can be driven now in the corresponding direction by passing the current in each of the drive coils3,4,25, and26.

As shown inFIG. 22, the end on the side of the stationary members6of the wire spring5is soldered to the elastic board23which is having the part fixed by the stationary members6attached in the base member7.

The E-shaped configuration is carried out, the width of face of the focusing direction is narrow in23ain part, and the elastic board23can carry out now rotation displacement of the tracking direction by being twisted as a main shaft by this partial23a.

Corresponding to the tangential tilt operation of the movable portion, stationary-portion part5eof the wire spring5of the elastic board23rotates by the edge of the wire spring5arranged on the different position in the focusing direction being fixed to position23bfrom which the radius of gyration in the rotation part of the elastic board23differs, respectively.

It is made to have not displaced the spot to the tangential direction by the tangential tilt operation by arranging the main shaft with which the elastic board23is twisted here in the same position as the principal point of the objective lens1in the focusing direction.

FIG. 24shows the objective lens drive apparatus of another preferred embodiment of the present invention, and the objective-lens holding member2holding the objective lens1is supported in elasticity in the present embodiment 12 with the wire spring5which makes the tangential direction the lengthening joint.

Spacing is separated to the focusing direction, a total of eight are arranged symmetrically and in parallel four by the tangential direction and each radial direction on each flat surface focusing on the optical axis of the objective lens1, and the wire spring5can set the end on the side of the stationary members6of the wire spring5in the both sides in the tangential direction of the movable portion to the elastic board24of the H character configuration by which a part for the center section is being fixed to the stationary members6. It is soldered to four edges24a, respectively.

Since it can displace to the tangential direction, the four edges24aof the elastic board24make the tangential tilt operation of the movable portion possible.

The elastic board24of the H character configuration is manufactured by contour processing by the press die, and the span in the focusing direction of edge24apossessing elasticity cannot be made not much narrow on the configuration of the die.

It is necessary to secure the width of face of the slot part about 1 mm.

When performing the tangential tilt operation of the movable portion, the amount of displacement to the direction of the axis of the wire spring5becomes the one where the span of the wire spring5in the focusing direction is narrower small.

The radius of gyration between the wire stationary portions on the side of the movable portion becomes small.

As for the deformation of the elastic board24, the one where the span of the wire spring5in the focusing direction is narrower becomes small. That is, the movability will become good.

Then, it is made for the moving-part side to become narrow as much as possible in the present embodiment to having set widely the span in the focusing direction of the wire spring5as the processible grade at the elastic board24side.

Moreover, since the objective lens1is generally arranged in the wire spring5at the optical disk installation close-attendants side when setting up narrowly the span on the side of the movable portion rather than the stationary member6side.

The wire spring5aon the side of optical disk installation in the focusing direction is shown inFIG. 25A. As shown inFIG. 25B, rather than only the same include angle makes wire spring5bof the opposite side incline in the opposite direction, respectively.

It is more desirable to install the wire springs5aand5brather than the center O1of the span between wire spring5aon the side of the stationary members6and5b, so that the method of center O2of the span between wire spring5aon the side of the movable portion and5bmay be on the optical disk installation side.

When the flexible board fleshed with the reinforcement member of suitable thickness is used for the elastic board24, it becomes possible to enable it to also perform current supply to the movable portion.

Moreover, resonance can be made to decrease by arranging the viscoelasticity ingredient in the clearance between the movable part of the elastic board24, and the stationary members6.

FIG. 26is the perspective diagram of the objective lens drive apparatus for explaining the preferred embodiment 13 of the present invention.

As the preferred embodiment in which the elastic board23is carrying out the E-shaped configuration in the preferred embodiment ofFIG. 22, and it is shown inFIG. 24.

It is made for the moving-part side to become narrow to having set widely the span in the focusing direction of the wire springs5aand5bas the processible grade at the elastic board23side.

InFIG. 26, the objective-lens holding member2holding the objective lens1is supported in elasticity with the wire springs5aand5bwhich make the tangential direction the lengthening joint.

The wire springs5aand5bseparate spacing to the focusing direction as mentioned above. It centers on the optical axis of the objective lens1, symmetrically with the tangential direction and each radial direction.

And a total of eight are arranged with four on each flat surface in parallel, and the end on the side of the stationary members6of the wire springs5aand5bis soldered to the elastic board23in the E-shaped configuration by which the part is being fixed to the stationary members6attached in the base member7.

In23a, the width of face of the focusing direction is narrow in part, and the elastic board23which carried out the E-shaped configuration can carry out now rotation displacement of the tracking direction by being twisted as a main shaft by this partial23a.

The tangential tilt operation of the movable portion is made possible by the edge of the wire spring5arranged on the different position in the focusing direction being fixed to position23bfrom which the radius of gyration in the rotation part of the elastic board23differs, respectively.

Although there are no restrictions on processing like the H mentioned already character type elastic board24in using the elastic board23which carried out the E-shaped type of the present embodiment, it becomes easy to be twisted by taking the large action radii of the rotation section of the elastic board23.

Therefore, the movability of direction which takes the large span of the focusing direction in the wire springs5aand5bon the side of the elastic board23of the tangential tilt direction improves.

The amount of displacement to the shaft orientations of the wire spring5when the one where the span of the wire of the focusing direction on the side of the movable portion is narrower carries out the tangential tilt operation of the movable portion is small.

The radius of gyration of the movable portion and the wire stationary portion is small.

As for the deformation of the elastic board23, the one where the span of the wire of the focusing direction on the side of the movable portion is narrower becomes small. That is, the movability becomes good.

As shown inFIG. 27, in the preferred embodiment 13, the span in the focusing direction in the wire springs5aand5bis constituted so that the span S2on the side of the movable portion may be narrowed as much as possible rather than the span S1on the side of the elastic board23.

Although the present embodiment 13 has composition of the preferred embodiment 11 and the preferred embodiment 12 which combined the configuration in part, the effectiveness will be further heightened by the above reasons by combining both.

It is possible to make it the light spot on the optical disk not displace the main shaft with which the elastic board23is twisted to the tangential direction by the tangential tilt operation like the preferred embodiment 11 by being arranged in the focusing direction in the same position as the principal point of the objective lens1.

Moreover, as shown inFIG. 28, the Lw1, and the principal-point m of the objective lens1and the optical disk installation side set the distance between the edges on the side of the movable portion of wire spring5bof the opposite side to Lw2for the distance between the edges on the side of the movable portion in wire spring5aon the side of the principal point m of the objective lens1, and optical media installation.

When the Ls1, and twist center-of-rotation n and optical disk installation side sets distance between the fixed-end sections in wire spring5bof the opposite side for the distance between the twist center of rotation n of the elastic board23in the focusing direction, and the fixed-end section in wire spring5aon the side of optical disk installation to Ls2.

Also by arranging so that it may be set to Ls1/Ls2=Lw1/Lw2, the cross action of the tangential direction by the tangential tilt operation can be reduced, and the fluctuation of the light spot position on the optical disk can be made small.

In the preferred embodiments, the work attached by carrying out the solder of the predetermined part is difficult, and positioning the wire springs5aand5busing the jig in the case of attachment, since the wire springs5aand5bare arranged.

Then, it is good to make the wire springs5aand5bthe composition which offsets to the tracking direction so that it may not interfere on each production at the support state of the objective-lens holding member in the preferred embodiment ofFIG. 29from the flat surface as a modification.

In the preferred embodiment, the support center of the tracking direction does not shift from the center of gravity or driving force center of the movable portion by arranging symmetrically to the flat surface parallel to the tangential direction including the optical axis of the objective lens1.

As shown in the perspective diagram which explains the support state of the objective-lens holding member in the preferred embodiment 15 shown inFIG. 30as other examples of composition which avoid the interference at the time of attachment, the objective-lens holding member2is supported in the end section of the rod-like flat spring17, and it is the hinge section about the other edges of the rod-like flat spring17.

The composition fixed to the stationary member26in which25is prepared can be considered.

The preferred embodiment 15 is the rod-like flat spring manufactured by etching or precision sheet metal work.

It arranges on the both-sides aspect in the tracking direction of the movable portion by making into the direction of the flat surface the flat surface which makes the tracking direction the perpendicular for17.

The rod-like flat spring17excises the unnecessary part by it, after thickness is making it about 50 micrometers and really casts the one plate-like member by this example to the objective-lens holding member2and the stationary member26.

The hinge section25of the hinge configuration in which the part rotates the tracking direction as a shaft is formed in the stationary member26, and rotation of the fixed-end section in the stationary member26of the rod-like flat spring17is attained.

By doing in this way, it is each rod-like flat spring.

The positioning accuracy to the span between17or the objective-lens holding member2, and the stationary member26can improve, and struggling between the individuals can also be made small.

FIG. 31is a diagram for explaining the preferred embodiment of the optical pickup device of the present invention which incorporates the objective lens drive apparatus of the preferred embodiment ofFIG. 1.

InFIG. 31,31is the light source,32is the collimator lens,33is the beam splitter,34is the starting mirror,35is the focusing lens,36is the rod-like lens,37is the light-receiving component,38is the optical disk, and39is the objective lens drive apparatus of the preferred embodiment.

The divergent light from the light source31turns into parallel light by the collimator lens32.

Then, it passes along the beam splitter33and the starting mirror34bends.

The parallel light bent by the starting mirror34is the objective lens drive apparatus3.

Incidence is carried out to the objective lens1of8, and the light spot S is formed on the optical disk38.

After the reflected light of the light spot S from the optical disk38is deflected by the beam splitter33and passes along the focusing lens35and the rod-like lens36, incidence of it is carried out to the light-receiving component37.

Thus, it arranges so that the reflected light of the light spot S on the optical disk38may carry out incidence to the light-receiving component37.

By generating the control signal and outputting to the objective lens drive apparatus39by objective-lens control means (not shown), such as the operation processing section, based on the signal acquired with the light-receiving component37, the focusing coil and the tracking coil are driven and the information recorded on the optical disk38can be reproduced by making the objective lens1follow to the optical disk38.

Furthermore, by the tilt sensor which is not illustrated detecting the inclination of the optical disk28, and passing the current according to it in the tilt coil (not shown) of the objective lens drive apparatus39, the objective lens1is made to incline to the optical disk38, and tilt compensation is performed.

Here, the objective lens drive apparatus39is this objective lens drive apparatus3, as it is the objective lens drive apparatus of the composition of each preferred embodiment explained by FIG.1–FIG. 30and being mentioned already.

Even when rotating surface blur, eccentricity, and the large optical disk38of the curvature at high speed by using9, it becomes possible to make the objective lens1follow to the optical disk38. That is, good recording or reproduction of the optical disk can be carried out at high speed.

FIG. 32shows an optical disk drive in which the optical pickup device ofFIG. 31is provided.FIG. 33is a front view of the optical disk drive ofFIG. 32.

InFIG. 32andFIG. 33, reference numeral40indicates the optical pickup device explained withFIG. 31, and the optical pickup device40includes the light source31, the collimator lens32, the rod-like lens36, the light-receiving component37, the objective lens drive apparatus39, etc.

Furthermore, reference numeral41indicates the housing of the optical disk drive,42indicates the cushion rubber,43indicates the spindle motor which is the rotation drive means of the optical disk38,44indicates the seek rail, and45indicates the pickup module base. The pickup module base45is attached to the housing41of the optical disk drive through the cushion rubber42.

The spindle motor43which carries out the rotation drive of the optical disk38is installed in the pickup module base45.

Moreover, the optical pickup device40is carried in the seek rail44attached in the pickup module base45.

The movement drive of the optical pickup device40is carried out in the radial direction of the optical disk28along the seek-rail44by the pickup drive means including the seeking motor (not shown).

The optical pickup device40provided in the optical disk drive shown inFIG. 32andFIG. 33can treat with the optical disk38about the objective lens1, even when the optical disk38rotated at high speed has surface blur, eccentricity or a large curvature of the surface, and it is possible to make the optical pickup device follow to the optical disk38.

Therefore, it enables the optical disk drive of this example of the preferred embodiment to perform recording/reproduction at high speed.

As described above, according to the objective lens drive apparatus of the present invention, it is possible to correct the inclination error of the optical disk and the objective lens. By making it possible to generate the driving force which can follow the optical disk under high-speed rotation to carry out the independent drive at each shaft orientations, the movability of the tangential tilt direction can be made good, and, the sensibility can be made small.

The optical disk drive of the present invention can perform stable control and it sets to the objective lens drive apparatus dealing with inclination compensation. The cross talk between the drive shafts which are easy to pose the problem can be reduced. Specifically, it is possible to reduce the cross talk including the cross talk of the tangential rotation direction generated by focusing translation drive, the cross talk of the tangential movement direction generated by focusing or tracking translation drive, and the cross talk of the tangential movement direction generated by the tangential rotation drive.

Next,FIG. 36shows the objective lens drive apparatus of another preferred embodiment of the invention.FIG. 37is a top view of the objective lens drive apparatus ofFIG. 36.FIG. 38is a side view of the objective lens drive apparatus ofFIG. 36.FIG. 39is an exploded view of the coils, yokes and magnets in the objective lens drive apparatus ofFIG. 36.FIG. 40AthroughFIG. 40Dare diagrams for explaining the tilt compensation operation.

The objective lens202is held by the objective-lens holding member203in the objective lens drive apparatus201of the present embodiment.

The objective-lens holding member203is elastically supported by four wire springs204a,204b,204cand204dwhich are the rod-like elastic support members. The through hole205of the shape of an angle made to penetrate in the vertical direction is formed in a part of objective-lens holding member203.

The focusing coils206aand206band the tracking coils207aand207bwhich are the driving coils by which the wire is wound to the shape of a flat-surface coil are fixed to the center section of the through hole205.

Movable portion208is constituted by these objective lenses202, the objective-lens holding member203, the focusing coils206aand206b, and the tracking coils207aand207b.

Moreover, in the objective lens drive apparatus201of the present embodiment, the group base209made from the magnetic substance which makes a part of stationary member is formed.

The yokes210aand210bwhich project in the through hole205on both sides which interpose the coils206a,206b,207a, and207bare formed in one by bending some group bases209.

Inside the yokes10aand10b, the coils6a,6b,7aand7band the magnets11aand11bfor the drive by the permanent magnet which forms the magnetic circuit with the yokes10aand10bso that the magnetic flux may pass through the inside are being fixed.

The relation between the coils6a,6b,7a, and7band the magnets11aand11bfor the drive is explained with reference toFIG. 39.

The magnets11aand11bfor the drive are divided into four sections along with the cross-like magnetization boundary lines a and b (4-pole magnetization).

The magnetization direction is magnetized in the range and the opposite direction which are perpendicular (the direction of the Z-axis-direction=jitter), and adjoin each other to the surface containing the two axial directions of the direction of the focus (Y-axis direction), and the tracking direction (X-axis direction).

Furthermore, the magnets11aand11bfor the drive are arranged so that the magnetization direction of the part which faces mutually on both sides of the focusing coils6aand6band the tracking coils7aand7bmay be in agreement.

Moreover, the four wire springs4a–4dhave the axial direction in parallel to the direction (the direction of the Z-axis-direction) perpendicualr to the surface containing the two axial directions of the focusing direction (Y-axis direction) and the tracking direction (X-axis direction).

On the flat surface (the first flat surface of the direction near the principal point of the objective lens2) of the imagination which intersects perpendicularly in the direction of the focus, make the tracking direction estrange the wire springs4aand4b, and they are arranged in parallel.

The tracking direction is made to estrange the wire springs4cand4don the flat surface (the second flat surface) of the imagination which intersects perpendicularly in the direction of the focus in the different position from the first flat surface, they are arranged in parallel, and support movable portion8(objective lens2) in elasticity to the two axial directions of the direction of the focus, and the tracking direction.

The end-winding child board12is fixed to the both sides of the objective-lens holding member3, and the wire springs [4a–4d] end side is being fixed to these end-winding child boards12by soldering.

The wire springs4a–4dother end edge is being fixed to the elastic board14as a movable portion which penetrated the stationary member13which is fixed on the group base9and constitutes a part of stationary member, and is attached in this stationary member13by soldering.

It fills up with the silicon system gel for making the wire springs in the stationary member134a–4dthrough hole part dump the wire here, and here, preventing resonance etc.

Moreover, the wire springs4a–4dare formed of the conductive ingredient, and current supply of them is enabled at Coils6a,6b,7a, and7bthrough the elastic board14of board composition, the wire springs4a–4d, and the end-winding child board12.

Moreover, while the elastic board14is attached on heights13aof the stationary member13, the ends side notches14aand14b, the wire springs4a–4d, it is constituted independently every as the deformation sections15a–15dwhich can deform in the direction of the jitter.

It is fixed to the wire springs4a–4don the stationary-portion side at the one end edge, and the deformation sections15a–15d, it is supported by possible displacement in the longitudinal direction (rod-like lengthening-joint=the direction of the jitter).

Moreover, near the deformation sections15a–15d, it is the drive source16is provided for tilt compensation.

The flat-surface coil-like coils17a–17dfor the tilt drive with which the drive source16for tilt compensation is fixed to each of the deformation sections15a–15dnear the edge. The pole of N and S is is set up for the permanent magnet18afixed to some group bases9in the position which is set up in the direction of the jitter and carries out proximity opposite at the coils17aand17cfor the tilt drive. The positions which similarly the pole of N and S is set up in the direction of the jitter, and carry out proximity opposite at the tilt drive coils17band17dare contained with the permanent magnet18bfixed to some group bases9.

The control to the coils17a–17dfor the tilt drive of each deformation section15a–15dis made possible to make the displacement in the direction of the jitter individually, and to carry out displacement in the opposite direction thereof or the direction of the jitter depending on the energization direction.

In addition, inFIG. 38, reference numeral19indicates the optical disk, and reference numeral20indicates the starting prism.

In such composition, the tilt compensation operation of the objective lens2will be explained.

The displacement of the deformation sections15aand15bwhich pass the current of the same direction and correspond to the coils17aand17bfor the tilt drive is made to carry out in the direction (the direction of outside) of P, as shown inFIG. 5C.

In connection with this, it displaces in the direction (the direction of outside) of P whose other end therefore, wire (also itself) and edge of the wire springs4aand4bon the first flat surface currently fixed to the deformation sections15aand15bare in the longitudinal direction.

As shown inFIG. 5C, to the coils17cand17dfor the tilt drive, the coils17aand17bfor tilt drive is about the deformation sections15cand15dwhich pass the current of the same direction to the reverse polarity, and correspond to it. The displacement is made to carry out in the direction (the inner direction) of Q, as shown inFIG. 5C.

In the present embodiment, it displaces in the direction (the inner direction) of Q whose wire springs on the second flat surface currently fixed to the deformation sections15c,15c,4cand4dat the other end, the wire springs are in the longitudinal direction.

That is, displacement is carried out so that the wire springs, i.e., the wire springs4aand4band the wire springs4cand4d, arranged in the position (the first flat surface and second flat surface) where the directions of the focus differ may offset the wire springs4a–4dother end edge of each other to the longitudinal direction (the direction of the jitter).

As shown inFIG. 5C, rotation displacement of the movable portion8supported at the wire springs4a–4dend side can be carried out to the tangential direction, and therefore, the compensation of the tangential tilt of the objective lens2is attained.

What is necessary is just to make the opposite direction offset at the time of the compensation of the tangential tilt of the opposite direction.

For this reason, it is necessary to be fixed to the wire springs4a–4dstationary-portion side, and also just to have the drive source216for tilt compensation in which enable displacement of the one end edge in the direction of the jitter by each deformation sections15a–15dof the elastic board14, and the displacement is made to perform, the compensation of the tangential tilt can be realized, without giving the load to the movable portion8.

Moreover, the thing for which the tangential tilt is corrected by carrying out displacement of the wire springs4a–4dother end edge to the longitudinal direction with high rigidity. The displacement of the other end edge can also be told to the end side as it is, it becomes what has the good flattery nature on the side of the movable portion8supported at the end side which are the wire springs4a–4dor good responsibility, and the tangential-tilt compensation which can respond also to high-speed operation is attained.

A description will be given of another preferred embodiment of the present invention with reference toFIG. 41throughFIG. 43B.

In the present embodiment, the elements which are essentially the same as corresponding elements in the previous embodiment are designated by the same reference numerals, and a description thereof will be omitted.

When the movable portion208is supported by the cantilever type similar to the previous embodiment, in connection with the tangential drive, the present embodiment shows the composition in which the countermeasure is taken in consideration of the point that the objective lens2displaces in the direction of the focus as shown inFIG. 40D.

In the objective lens drive apparatus of the present embodiment, the objective lens202is considered as the composition of central arrangement, and the wire spring, the elastic board, and the drive source for tilt compensation are established in the both sides of the direction of the jitter of the movable portion208so that it may become symmetrical to the straight line of the tracking direction passing through the objective-lens center.

Specifically, in the present embodiment, the wire springs204a–204d, the elastic board214(the deformation sections215a–215d), the wire springs222a–222dof the same composition corresponding to the source216(the tilt drive coils217a–217dand the permanent magnets218aand218b) for the tilt drive compensation, the elastic board223(the deformation sections224a–224d) and the source225(the tilt drive coils226a–226dand the permanent magnets27aand27b) for the tilt drive compensation are provided in the reverse side in the direction of the jitter.

The stationary member228corresponding to the stationary member213is also provided.

Therefore, in the present embodiment, the wire springs204a,204b,222a, and222bare arranged on the first flat surface, and the wire springs204c,204d,222c, and222dare arranged on the second flat surface.

In addition, with the present embodiment, the yokes210aand210band the magnets211aand211bfor the drive are arranged in the both sides of the direction of the jitter on both sides of the objective lens202, and the tracking coils207aand207bare also arranged in both sides.

But about the focusing coil, it replaces with the flat-surface coil-like focusing coils206aand206b, and the focusing coil229by which the wire is wound to the circumference of movable portion208in the shape of a cylinder is used.

In such composition, tilt compensation operation of the objective lens202will be explained with reference to FIG.42A–FIG. 42C.

The displacement of the deformation sections215a,215b,224a, and224bwhich correspond by control to the coils217a,217b,226a, and226bfor the tilt drive is made to carry out in the direction of P, as shown inFIG. 42C.

In the present embodiment, it displaces in the direction of P whose other end therefore, wire (also itself) and edge of the wire springs204a,204b,222a, and222bon the first flat surface currently fixed to the deformation sections215a,215b,224a, and224bare in the longitudinal direction.

On the other hand, the displacement of the deformation sections215c,215d,224c, and224dwhich correspond by control to the coils217c,217d,226c, and226dfor the tilt drive is made to carry out in the direction of Q, as shown inFIG. 40C.

In the present embodiment, it displaces in the direction of Q whose wire springs on the second flat surface currently fixed to the deformation sections215c,215c,224c,224d,204c,204d,222c, and222dat the other end, the wire springs are in the longitudinal direction.

Namely, the wire springs arranged in the position (the first flat surface and second flat surface) where the directions of the focus differ in the wire springs204a–204dand the other end edge (222a–222d).

That is, displacement is carried out so that the wire springs204aand204b, the wire springs204cand204dand the wire springs222aand222b, and the wire springs222cand222dmay offset mutually to the longitudinal direction (the direction of the jitter).

As shown inFIG. 40C, rotation displacement of the wire springs204a–204dand the movable portion208supported at the end222a–222dside can be carried out to the tangential direction, and therefore, the compensation of the tangential tilt of the objective lens202is attained.

Of course, what is necessary is just to make the opposite direction offset at the time of the compensation of the tangential tilt of the opposite direction.

By the way, when it decomposes into every one side and such tangential-tilt compensation operation is considered, it comes to be shown inFIG. 43AandFIG. 43B.

Namely, considering tangential-tilt compensation operation on the side of the wire springs204a–204d, as opposed to the direction cross action of the jitter occurring in the direction shown by the arrow head R to the objective lens202of the movable portion208.

Considering tangential-tilt compensation operation on the side of the wire-springs222a–222d, by the direction cross action of the focus occurring to the opposite direction as shown by the arrow head S to the objective lens202of the movable portion208, and offsetting these direction cross actions of the focus.

The tangential-tilt compensation operation which the fluctuation of the direction of the focus does not produce as the whole is attained.

Moreover, in order to reduce the direction cross action of the jitter accompanying tangential-tilt compensation operation, in composition as shown in the form of the first operation, the amount of displacement to the direction of the jitter of the other end edge of the wire springs204aand204bof the direction near the principal-point side of the objective lens202.

It is possible to make it bring the rotation center for tangential-tilt compensation close to the principal point of the objective lens202as much as possible by making it smaller than the amount of displacement to the direction of the jitter of the wire springs204cand204dof the one distant from the principal-point side of the objective lens202at the other end edge.

In this case, the thing for which reinforcement (rigidity) of the deformation sections215aand215bis made stronger than deformation sections215cand215dreinforcement (rigidity) although giving the difference to the amount can also be realized, according to adjustment of the amount of drive with the coils217a,217b,217c, and217dfor the tilt drive, it can realize more easily.

Moreover, making the wire springs204aand204b, the wire springs204cand204dand the wire springs222aand222b, and the wire springs222cand222doffset in the direction of the jitter in tangential-tilt compensation operation, the other end edge of the wire springs204a,204b,222a, and222bmay be position fixation.

FIG. 44shows such modification in which it is the wire springs204c,204d,222cand222dat the other end edge, the deformation sections215c,215d,224cand224d, it fixes in the direction of the jitter (the longitudinal direction) possible, the coils217c,217d,226c, and226dfor the tilt drive, and the permanent magnets218a,218b,227a, and227b.

In addition, the first flat surface of the imagination in which the wire springs204a,204b,222a, and222bare arranged is set as the position passing through the principal point of the objective lens202.

The displacement only of the deformation sections215c,215d,224c, and224dis made to carry out in the direction of the jitter with the coils217c,217d,226c, and226dfor the tilt drive, and the permanent magnets218a,218b,227a, and227bat the time of the compensation of the tangential tilt, and the displacement only of the wire springs other end edge is made to carry out in the direction of the jitter (the longitudinal direction).

The wire springs204a,204b,222aand222bside is fixed and it does not displace the movable portion208the near principal point of the objective lens202, the rotation center carrying out the displacement for tangential-tilt compensation, the occurrence of the direction cross action of the jitter can be prevented.

In addition, this method is applicable similarly in the case of the single-sided support method like the previous embodiment ofFIG. 36.

Next, a description will be given of another preferred embodiment of the present invention with reference toFIG. 45and FIG.46A–FIG. 46D.

The objective lens drive apparatus of the present embodiment takes into consideration not only the compensation of the tangential tilt but the compensation of the radial tilt.

The straight line of the direction of the jitter where the wire springs204a–204dand222a–222dpass along the objective-lens202optical axis by the objective lens drive apparatus of this embodiment on each flat surface although fundamental composition applies to the objective lens drive apparatus shown with the present embodiment, and it is made to incline and is arranged.

The configuration to which the wire springs204a,204b,222a, and222bare seen from the focus to the direction of the jitter which passes along the objective-lens202optical axis on the first flat surface, its moving-part208side is narrow, and the elastic board214and223side becomes large, and it is made to incline and is arranged.

In the direction of the focus to the direction of the jitter which is the same also as for the wire springs204c,204d,222c, and222d, and passes along the objective-lens202optical axis on the second flat surface, and elastic board214and223side becomes the movable portion side narrow widely, and it is made to incline and is arranged.

Also in such composition, it can carry out by the same control as the case where it mentions above, at the time of the compensation of the tangential tilt.

That is, the displacement of the deformation sections215a,215b,224a, and224bwhich correspond by control to the coils217a,217b,226a, and226bfor the tilt drive as well as the case ofFIG. 42Cis made to carry out in the direction of P.

In connection with this, it displaces in the direction of P whose other end therefore, wire and edge of the wire springs204a,204b,222a, and222bon the first flat surface currently fixed to the deformation sections215a,215b,224a, and224bare in the longitudinal direction.

On the other hand, the displacement of the deformation sections215c,215d,224c, and224dwhich correspond by control to the coils217c,217d,226c, and226dfor the tilt drive as well as the case ofFIG. 42Cis made to carry out in the direction of Q.

In connection with this, it displaces in the direction of Q whose wire springs on the second flat surface currently fixed to the deformation sections215c,215c,224c,224d,204c,204d,222c, and222dat the other end, the wire springs are in the longitudinal direction.

Namely, the wire springs arranged in the position (the first flat surface and second flat surface) where the directions of the focus differ in the wire springs4a–4dand the other end edge (222a–222d).

That is, the displacement is carried out so that the wire springs204aand204b, the wire springs204cand204dand the wire springs222aand222b, and the wire springs222cand222dmay offset mutually to the longitudinal direction (the direction of the jitter).

The rotation displacement of the wire springs204a–204dand the movable portion208supported at the end222a–222dside can be carried out to the tangential direction by this, and, therefore, the compensation of the tangential tilt of the objective lens202is attained.

On the other hand, the compensation operation of the radial tilt will be explained with reference to FIG.46A–FIG. 46D.

In this case, what is necessary is just to carry out displacement relatively so that the groups may offset them mutually to the longitudinal direction, using as the group the wire springs arranged in the position where it is arranged in the position where the tracking directions differ, and the directions of the focus differ the other end edge of the wire spring fixed to the stationary-portion side.

For example, the displacement of the deformation sections215a,215d,224b, and224cwhich correspond by the control to the tilt drive coils217a,217d,226b, and226cis made to carry out in the direction of P, as shown in FIG.46A–FIG. 46D.

In the present embodiment, it displaces in the direction of P whose other end therefore, wire and edge of the wire springs204a,204d,222b, and222ccurrently fixed to the deformation sections215a,215d,224b, and224care also the direction of the jitter (the longitudinal direction).

On the other hand, the control to the coils217b,217c,226a, and226dfor the tilt drive makes the displacement of the deformation sections215b,215c,224a, and224dwhich correspond as opposition control carry out in the direction of Q, as shown inFIG. 46B.

In the present embodiment, it displaces in the direction of Q whose wire springs which are being fixed to the deformation sections215b,215c,224a,224d,204b,204c,222a, and222dat the other end the wire springs are in the direction of the jitter (the longitudinal direction).

In such operation, each of the wire springs204a–204dand222a–222dis inclined, and the vector is as shown inFIG. 46Ain the connection section to the movable portion208, and the partial output to the tracking direction according to the direction is also produced.

As shown inFIG. 46C, when the partial-output component of this tracking direction is considered in the direction of the jitter, the moment to rotate in the radial tilt direction the movable portion208appears as shown inFIG. 46C. As shown inFIG. 46D, the compensation of the radial tilt of the movable portion208(the objective lens202) is possible.

What is necessary is just to make the opposite direction drive at the time of the compensation of the radial tilt of the opposite direction.

Therefore, if it controls combining the compensation of the tangential tilt, the compensation of the tangential tilt of the objective lens202and the radial tilt will be attained.

For this reason, it carries out inclination arrangement in the symmetrical state to the straight line of the wire springs204a–204d, the first which intersect perpendicularly222a–222din the direction of the focus, and the direction of the jitter which passes along the lens center on the second flat surface and is fixed to the stationary-portion side the one end edge the deformation sections215a–215dand224a–224dcarrying out the sources216and225, the compensation of the tangential tilt or the radial tilt can be realized without giving the load to the movable portion208.

Moreover, the thing for which the compensation of the tangential tilt or the radial tilt is performed by carrying out displacement of the wire springs204a–204dand the other end edge (222a–222d) to the longitudinal direction (the direction of jitter) with high rigidity.

It becomes what has the good flattery nature on the side of wire springs204a–204d,222a–222dthe movable portion208supported at the end side or good responsibility, and the compensation of the tangential tilt which can respond also to high-speed operation, or the radial tilt is attained.

In addition, although cross action of the tracking direction may occur in the objective lens drive apparatus of the present embodiment when the positions of the center of rotation of the movable portion208and the principal point of the objective lens202differ at the time to the radial direction.

As the countermeasure, the wire springs204a,204b,222a,222bare made to arrange in the first direction near the principal point of the objective lens202, and the displacement of the wire springs204c,204d,222c, and222din the longitudinal direction are made to arrange in the second direction where the amount is distant from the principal point of the objective lens202in the longitudinal direction if it is made to become smaller than the amount.

Displacement operation for radial tilt compensation can be made to be able to perform as much as possible by the ability setting near the principal point of the objective lens202as the rotation center, and the direction cross action of the track can be made to mitigate.

This is the same also about the direction cross action of the jitter at the time of tangential-tilt compensation.

It is possible to make it the wire springs204a,204b,222aand222bthe amount of displacement in the longitudinal direction become small as means for this by adjustment of the amount of drives by the drive sources216and225for tilt compensation.

The degree of slope angle of the wire springs204a,204b,222a, and222bmade to arrange on the first direction near the principal point of the objective lens202is made smaller than the degree of slope angle of the wire springs204c,204d,222c, and222dmade to arrange on the second direction distant from the principal point of the objective lens202.

Even if it is the amount of the same drive, it is possible to make the wire springs204a,204b,222aand222barranged with the amount of displacement in the longitudinal direction become small.

It is possible to make it arranged with the degree of slope angle=0. In the extreme example, the wire springs204a,204b,222a, and222bare made to arrange on the first direction near the principal point of the objective lens202in parallel.

Moreover, in compensation operation of the radial tilt or the tangential tilt, as long as it is relative to make the wire spring offset in the direction of the jitter, it may be good, for example, the other end edge of the wire springs204a,204b,222a, and222bmay be position fixation.

It is fixed in the direction of the jitter (the longitudinal direction) with possible displacement by the deformation sections215c,215d,224cand224d. Namely, in the example shown inFIG. 44applying correspondingly the wire springs204c,204d,222cand222don the other end edge is possible.

The displacement drive is enabled with the coils217c,217d,226c, and226dfor the tilt drive, and the permanent magnets218a,218b,227a, and227b.

It is possible to make it set the first flat surface of the imagination in which the wire springs204a,204b,222a, and222bare arranged as the position passing through the principal point of the objective lens202.

According to this, displacement operation the object for tangential-tilt compensation and for radial tilt compensation can be made to be able to perform by the ability setting near the principal point of the objective lens202as the rotation center, and, therefore, the direction cross action of the jitter and the direction cross action of the track can be prevented.

In addition, in the present embodiment, the example of the both-sides support method has been explained to the movable portion208according to the previous embodiment, and in the case of the single-sided support method according to the previous embodiment, it is applicable similarly.

Moreover, it is possible to make the wire springs204a–204dand222a–222dincline in the shape of a character to which it sees in the direction of the focus conversely although the wire springs204a–204dand222a–222dare made to incline so that it may see in the direction of the focus with this embodiment and the elastic board214and223side may become the movable portion208side narrow widely, and the elastic board214and223side.

Moreover, although the example which attaches the coil in the elastic boards214and223side, and attaches the magnet in the group base209side is explained the drive sources216and225for tilt compensation with the present embodiment, the coil is attached in the group base209side, and it is possible to make it attach the magnet in the elastic boards214and223side conversely.

Furthermore, in order to reduce components mark and to raise attachment nature, the elastic boards214and223may be formed with the print coil, or you may constitute so that the magnetic leakage flux of the magnets211aand211bfor the drive for the moving-part drive may pierce through the coil for the tilt drive.

Moreover, the drive source for tilt compensation is provided as well as in the combination of such a magnet and a coil as inFIG. 47.

The piezoelectric devices232a–232dmade to intervene individually between each deformation sections215a–215dof the elastic board214and the stationary member213are used as a drive source for tilt compensation.

Displacement of the each deformation sections215a–215dleading edge is carried out, and it may be made to carry out displacement of the wire springs204a–204dother edge to the longitudinal direction by the slight drive of the piezoelectric devices232a–232d. According to this, highly precise tilt compensation is attained.

A description will be given of another preferred embodiment of the present invention wither reference toFIG. 48.

In the present embodiment, the example of application to the optical pickup device242equipped with the objective lens drive apparatus of one preferred embodiment of the present invention is shown.

The divergent light, output from the light source243, such as a semiconductor laser carried in the optical pickup device242, is converted into the parallel light by the collimator lens244.

Then, it passes along the beam splitter245and the starting mirror246(it is equivalent to the starting prism220) bends.

Incidence of the parallel light bent by the starting mirror246is carried out to the objective lens202of the objective lens drive apparatus241carried in the optical pickup device242, and it forms the spot on the optical disk219.

After the reflected light of the spot changes the direction and polarity which came by the beam splitter245and passes along the condenser lens247and the rod-like lens248, it is incident to the 4-division light-receiving component249.

It arranges so that the reflected light of the spot on the optical disk219may carry out incidence to the 4-division light-receiving component249.

The information on the optical disk219can be acquired by making the objective lens202follow to the optical disk219by carrying out based on the signal acquired with the 4-division light-receiving component249, and driving the focusing coils206aand206band the tracking coils207aand207bof the objective lens drive apparatus241.

The light-receiving optical system250is constituted by the condenser lens247, the rod-like lens248, and the 4-division light-receiving component249.

Furthermore, the objective-lens control drive (not shown) which outputs the drive signal over the objective lens drive apparatus241based on the received light signal of the 4-division light-receiving component249is also provided.

The objective lens drive apparatus241in the optical pickup device242is one preferred embodiment of the present invention described above, and the objective lens202is made to follow to the optical disk219by the objective lens drive apparatus241as mentioned above and the information on the optical disk219is read. The control of the influence of the tangential tilt or the radial tilt of the objective lens drive apparatus241is attained at the time of the objective-lens drive.

A description will be given of another preferred embodiment of the present invention with reference toFIG. 49andFIG. 50.

In the present embodiment, the example of application to the optical disk drive which incorporates the optical pickup device242mentioned above is shown.

As shown inFIG. 49andFIG. 50, the pickup module base253is installed in the housing251of the optical disk drive through the rubber cushion252.

The spindle motor254as a rotation drive system which rotates the optical disk219is fixed to the pickup module base253.

Moreover, the optical pickup device242is provided with the seek rail255attached in the pickup module base253.

Movement to radial of the optical disk219of the optical pickup device242is enabled in the seek rail255.

The optical pickup device242carried in the optical disk drive concerned is the optical pickup device which is mentioned above and which is explained with the form of the fourth operation, and is the optical pickup device in which few control of the influence of the tangential tilt or the radial tilt is possible at the time of the objective-lens drive. Therefore, when it is easy to be influenced of the tilt like DVD, the convenient optical disk drive can be offered.

Next,FIG. 51shows the composition of the optical disk drive of another preferred embodiment of the present invention.

The optical disk drive320ofFIG. 51includes the spindle motor322for carrying out the rotation drive of the optical disk315, the optical pickup device (OPD)323, the laser control circuit324, the encoder325, the motor driver327, the reproduction signal-processing circuit (RSP)328, the servo controller333, the buffer RAM334, the buffer manager337, the interface338, the ROM339, the CPU340, the RAM341, and the tilt sensor342, etc.

In addition, the arrow head inFIG. 51does not show the flow of the typical signal or information, and does not express connection-related all of each block.

Moreover, in the present embodiment, the information storage medium based on the specification of the DVD (digital versatile disc) system as an example is used as the optical disk315.

The optical pickup device323is equipment for receiving the reflected light from the record surface of the optical disk315while irradiating laser light to the predetermined position of the recording surface of the optical disk315in which the track in the spiral or concentric-circle formation is formed.

The reproduction signal processing circuit328includes the first I/V amplifier328a, the servo signal detector328b, the wobble-signal detector328c, the RF signal detector328d, the decoder328e, the second I/V amplifier328f, and the tilt detector328g, as shown inFIG. 52.

The first I/V amplifier328aperforms amplification with a predetermined gain while it changes into the voltage signal the current signal which is the output signal of the optical pickup device323.

The servo signal detector328bdetects servo signals (the focusing error signal, tracking error signal, etc.) based on the voltage signal from the first I/V amplifier328a. The servo signal detected is outputted to the servo controller333.

The wobble-signal detector328cdetects the wobble signal based on the voltage signal from the first I/V amplifier328a.

The RF signal detector328ddetects the RF signal based on the voltage signal from the first I/V amplifier328a.

The decoder328eextracts ADIP (Address In Pregroove) information, the synchronizing signal, etc. from the wobble signal detected by the wobble-signal detector328c.

The ADIP information extracted is outputted to the CPU340, and the synchronizing signal is outputted to the encoder325.

Moreover, after the decoder328eperforms recovery processing, error-correction processing, etc. to the RF signal detected by the RF signal detector328d, it is stored in the buffer RAM334through the buffer manager337as reproduction data.

In addition, when reproduction data are music data, it is outputted to the external audio instrument.

The second I/V amplifier328fperforms amplification with a predetermined gain while it changes into the voltage signal the current signal which is the output signal of the tilt sensor342.

The tilt detector328gdetects the information about the media tilt based on the voltage signal from the second I/V amplifier328f. The information about the media tilt detected is outputted to the servo controller333as the tilt information signal.

Referring back toFIG. 51, the servo controller333generates the various control signals for controlling the optical pickup device323based on the servo signal, and outputs them to the motor driver327.

Moreover, the servo controller333generates the tilt compensation signal for correcting the inclination of the record side based on the tilt information signal, and outputs it to the motor driver327.

The motor driver327outputs the drive signal to the optical pickup device323based on the control signal and tilt compensation signal from the servo controller333.

Moreover, the motor driver327outputs the drive signal to the spindle motor322based on directions of CPU340.

The buffer manager337notifies I/O of the data to the buffer RAM334to CPU340that it manages and the accumulated amount of data turns into the predetermined amount.

It is written in synchronizing with the synchronizing signal from the reproduction signal processing circuit328, and outputs the signal to the laser control circuit324while the encoder325takes out the data accumulated at the buffer RAM334based on directions of CPU340through the buffer manager337, performs abnormal conditions of data, addition of the error correction code, etc. and generates the write-in signal to the optical disk315.

The laser control circuit324controls the output of the laser light irradiated to the optical disk315based on directions of the write-in signal from the encoder325, and the CPU340.

The interface338is the bidirectional communication interface with the host (for example, personal computer), and is based on the standard interfaces, such as ATAPI (AT Attachment Packet Interface) and SCSI (Small Computer System Interface).

The program described in code decipherable by the CPU340is stored in the ROM339.

And the CPU340saves data required for control etc. temporarily at the RAM341while controlling operation of each part of the above according to the program stored in the ROM339.

Next, the composition of the optical pickup device323etc. is explained using FIG.53–FIG. 61.

The optical pickup device323is the spindle motor as shown inFIG. 53.

The pickup body301which receives the reflected light from the record side while irradiating laser light to the record side of the optical disk315which is rotating by322, the two seek rails302which guide movement to the X-axis direction (space longitudinal direction) of the pickup body301while holding this pickup body301, and the pickup body.

It is constituted including the seeking motor301(not shown) for driving to the X-axis direction.

The pickup body301is stored in the center of housing371and this housing371, and includes the light-beam output system312which acts in the direction perpendicular to the record side of the optical disk315as the outgoing light beam whose wavelength is 660 nm, and the focusing system311which focuses the light beam from the light-beam output system312in the predetermined position of the recording surface of the optical disk315.

The light-beam output system312is equipped with the light source unit351, the coupling lens352, the beam splitter354, the starting mirror356, the detection lens358, the cylindrical lens357, and the photodetector359, as shown inFIG. 54.

The light source unit351is equipped with the semiconductor laser (not shown) as a light source which emits light in the light beam whose wave length is 660 nm. The light source unit351is fixed to the housing371so that the direction with the maximum intensity of the outgoing light beam output from the light source unit accords with the direction of +X.

The coupling lens352is arranged at the +X side of the light source unit351, and makes the outgoing beam abbreviation parallel light.

The beam splitter354is arranged at the +X side of the coupling lens352, and branches the reflected light (return light beam) from the record side of the optical disk315in the direction of −Y.

The starting mirror356is arranged at the +X side of the beam splitter354, and changes the direction with the maximum intensity of the outgoing beam through the beam splitter354into the direction of +Z.

The direction with the maximum intensity carries out incidence of the outgoing beam changed into +Z direction to the focusing system11through the opening of the housing371by the starting mirror356.

The detection lens358is arranged at the −Y side of the beam splitter354, and condenses the return light beam which branched in the direction of −Y by the beam splitter354.

The cylindrical lens357is arranged at the −Y side of the detection lens358, and operates orthopedically the return light beam condensed with the detection lens358.

The photodetector359is arranged at the −Y side of the cylindrical lens357, and receives the return light beam orthopedically operated by the cylindrical lens357in respect of the the received light.

The 4-division light-receiving component is used for the photodetector359, and the signal according to the amount of the received light is outputted to the reproduction signal processing circuit328from each light-receiving component, respectively.

That is, while leading the light beam which acted as Idei from the semiconductor laser to the focusing system11, the optical path length for leading the return light beam to the photodetector359is formed in the center of housing371.

FIG. 55shows the focusing system in the optical pickup device ofFIG. 53.FIG. 56Ashows the focusing system in the optical pickup device ofFIG. 53.FIG. 56Bis a cross-sectional view of the focusing system taken along the line A—A inFIG. 55A.

As shown, the focusing system311includes the objective lens360, the lens holder381as a lens holding member, the first tracking coil382a, the second tracking coil382b, the first focusing coil384a1, the second focusing coil384a2, the third focusing coil384b1, the fourth focusing coil384b2, the base plate385, the first yoke386a, the second yoke386b, the stem387as a stationary member, the first radial tilt coil388a, the second radial tilt coil388b, the first permanent magnet391a, the second permanent magnet391b, the six line springs (referred to as392a1,392a2,392a3,392b1,392b2, and392b3) that have the conductivity as an elastic member, and the board393.

The base plate385is a rectangular plate-like member and the base plate is provided with the opening at the center portion thereof, which has the shape corresponding to that of the opening of the housing371. The longitudinal direction of the base plate385corresponds to the Y-axis direction, and the side surface of the base plate385is attached to the surface of the housing371on the side of +Z direction so that the opening may lap with the opening of the housing371. In addition, the base plate385serves as a yoke for forming the magnetic circuit.

The first yoke386aand the second yoke386bare the plate-like members having the same configuration, and they have the predetermined positional relation and are fixed to the base plate385. The first yoke386ais arranged at +Y side edge section of the base plate385, and the second yoke386bis arranged at −Y side edge section of the base plate385.

The stem387is the block-like member, and is attached to the surface on the side of +Y of the first yoke.

The through holes extending in the Y-axis direction are formed in this stem387at the three locations near the side edge of +X and at the three locations near the side edge of −X, respectively.

The first permanent magnet391aand the second permanent magnet391bare the block-like permanent magnets having the same shape mostly.

The first permanent magnet391ais attached to the surface on the side of −Y of the first yoke, and the second permanent magnet391bis attached to the surface on the side of +Y of the second yoke.

That is, the surface on the side of −Y of the first permanent magnet391aand the surface on the side of +Y of the second permanent magnet391bconfront each other with respect to the Y-axis direction.

The surface on the side of −Y of first permanent magnet391ais divided into the four ranges, each having equal magnitude, by the magnetization limits CP1of the X-axis direction and the magnetization limits CP2of the Z-axis direction as shown inFIG. 57A.

In the present embodiment, the range RC1is indicated as the range which is located on the +Z side of the magnetization limits CP1and on the −X side of the magnetization limits CP2. The range RC2is indicated as the range which is located on the +Z side of the magnetization limits CP1and on the +X side of the magnetization limits CP2. The range RC3is indicated as the range which is located on the −Z side of the magnetization limits CP1and on the −X side of the magnetization limits CP2. The range RC4is indicated as the range which is located on the −Z side of the magnetization limits CP1and on the +X side of the magnetization limits CP2. In addition, the adjacent ranges have the reversed polarity mutually.

The surface on the side of +Y of the second permanent magnet391bis divided into the four ranges, each having the equal magnitude, by the magnetization limits DP1of the X-axis direction, and the magnetization limits DP2of the Z-axis direction as shown inFIG. 57B.

In the present embodiment, the range RD1is indicated as the range which is located on the +Z side of the magnetization limits DP1and on the −X side of the magnetization limits DP2. The range RD2is indicated as the range which is located on the +Z side of the magnetization limits DP1and on the +X side of the magnetization limits DP2. The range RD3is indicated as the range which is located on the −Z side of the magnetization limits DP1and on the −X side of the magnetization limits DP2. The range RD4is indicated as the range which is located on the −Z side of the magnetization limits DP1and on the +X side of the magnetization limits DP2. In addition, the adjacent ranges have the reversed polarity mutually.

Therefore, the range RC1and the range RD1, the range RC2and the range RD2, the range RC3and the range RD3, and the range RC4and the range RD4confront each other, respectively. Moreover, the range RC1and the range RD1, the range RC2and the range RD2, the range RC3and the range RD3, and the range RC4and the range RD4have the reversed polarity mutually, respectively.

Referring back toFIG. 55, the base board393is partially fixed to the surface on the side of +Y of the stem387through a damping material, and provided with the plural input terminals and output terminals. The plural signal lines of the motor driver327are connected to the input terminals, respectively.

In addition, the base board393is provided to have some elastic deformation in the Y-axis direction, in order to absorb vibrations of the Y-axis direction.

The lens holder381is provided to have a cube-like configuration, and it is arranged between the first permanent magnet391aand the second permanent magnet391b.

Moreover, as shown inFIG. 56B, the through hole extending in the Z-axis direction used as the optical path length of the outgoing beam from housing371is formed in the center section of the lens holder381.

In the edge on the side of +Z of the through hole, it is arranged so that the optical axis and main shaft of the through hole of the objective lens360may correspond mostly.

FIG. 58AthroughFIG. 58Dshow the respective coils for driving the lens holder381in the present embodiment.

The lens holder381includes the first tracking coil382a, the second tracking coil382b, the first radial tilt coil388a, the first focusing coil384a1, the second focusing coil384a2, the third focusing coil384b1, the fourth focusing coil384b2, and the second radial tilt coil388bwhich are unified at the predetermined position relation respectively.

As the objective lens360, the lens holder381, and each coil are united and are moved together, and these components are unified and will be called the movable portion.

The terminal (referred to as Ta3and Tb3) for supplying the drive current-to the terminal (referred to as Ta2and Tb2) for supplying the drive current to the terminal (referred to as Ta1and Tb1) for supplying the drive current to each coil for radial tilts and each coil for the trackings and each coil for the focuses is prepared in the lens holder381.

In the present embodiment, the terminals Ta1, Ta2, and Ta3are formed in the surface on the side of −X of the lens holder381, and the terminals Tb1, Tb2, and Tb3are formed in the surface on the side of +X of the lens holder381.

And the end of the line spring392a1is connected to the terminal Ta1, the end of the line spring392a2is connected to the terminal Ta2, and the end of the line spring392a3is connected to the terminal Ta3.

Moreover, the end of the line spring392b1is connected to the terminal Tb1, the end of the line spring392b2is connected to the terminal Tb2, and the end of the line spring392b3is connected to the terminal Tb3.

Each line spring is extending in the Y-axis direction, and those other edges are connected to the output terminal of the board393by soldering etc. through the through hole prepared in the stem387, respectively. That is, the movable portion is supported by the stem387in elasticity through the six line springs.

In addition, in the present embodiment, it is set up so that the support center (referred to as S92) with each line spring may be mostly in agreement with the center of inertia (referred to as Sk) of movable portion.

The first coil384a1for the focuses, the second coil384a2for the focuses, the third coil384b1for the focuses, and the fourth coil384b2for the focuses are the coils of the same configuration mostly mutually. And it is connected by each coil for the focuses so that the same drive current may be supplied.

The first coil384a1for the focuses and the second coil384a2for the focuses are located in the +Y side of the lens holder381, respectively as shown inFIG. 59A.

It is arranged at the position which counters almost equally to the range RC1and the range RC3of the first permanent magnet391a, and the coil384a1and the coil384a2are arranged at the position which counters almost equally to the range RC2and the range RC4of the first permanent magnet391a.

The third coil384b1and the fourth coil384b2are located on the −Y side of the lens holder381, respectively as shown inFIG. 59B.

It is arranged at the position which counters almost equally to the range RD1and the range RD3of the second permanent magnet391b, and the coil384b1and the coil384b2are arranged at the position which counters almost equally to the range RD2and the range RD4of the second permanent magnet391b.

Thereby, when the drive current is supplied to the first focusing coil384a1, as shown inFIG. 60A, based on the current flowing through the coil384a1and the magnetic flux from the range RC1and the range RC3of the first permanent magnet391a, the force (first focal force: Ff1) occurs in +Z direction (or −Z direction).

When the drive current is supplied to the coil384a2, based on the current flowing through the coil384a2and the magnetic flux from the range RC2and the range RC4of the first permanent magnet391a, the force (second focal force: Ff2) occurs in +Z direction (or −Z direction), which is the same direction as the first focal force.

When the drive current is supplied to the third focusing coil384b1, based on the current flowing through the coil384b1and the magnetic flux from the range RD1and range RD3of the second permanent magnet391b, as shown inFIG. 60B, the force (third focal force: Ff) occurs in +Z direction (or −Z direction), which is the same direction as the first focal force.

When the drive current is supplied to the fourth focusing coil384b2, based on the current flowing through the coil384b2and the magnetic flux from the range RD2and the range RD4of the second permanent magnet391b, the force (fourth focal force: Ff4) occurs in +Z direction (or −Z direction), which is the same direction as the first focal force.

In the present embodiment, it is set up so that each focal force may serve as the same magnitude mutually, the movable portion will be driven to +Z direction (or −Z direction) according to the magnitude of the drive current.

In addition, the driving direction can control each coil for the focuses based on the flowing current.

Moreover, each coil for the focuses has the magnitude and the configuration according to the driving force needed.

The first tracking coil382aand the second tracking coil382bare the coils of the same configuration mostly mutually.

The first tracking coil382ais on the +Y side of the lens holder381, and arranged at the position which counters almost equally to the range RC1and the range RC2of the first permanent magnet391a, as shown inFIG. 59A.

The second tracking coil382ais on the −Y side of the lens holder381, and arranged at the position which counters almost equally to the range RD1and the range RD of the second permanent magnet391b, as shown inFIG. 59B.

In addition, a part of the first tracking coil382aoverlaps a part of the first focusing coil384a1and a part of the second focusing coil384a2about the Y-axis direction.

Similarly, a part of the second tracking coil382boverlaps a part of the first focusing coil384a1and a part of the second focusing coil384a2about the Y-axis direction.

Moreover, it is connected so that the same drive current may be mutually supplied to the first tracking coil382aand the second tracking coil382b.

Thereby, when the drive current is supplied to the first tracking coil382a, as shown inFIG. 60C, based on the flowing current and the magnetic flux from the range RC1and the range RC2of the first permanent magnet391a, the force (first tracking force: Ft1) occurs in the direction of +X (or the direction of −X).

On the other hand, when the drive current is supplied to the second tracking coil382b, as shown inFIG. 60D, based on the flowing current and the magnetic flux from the range RD1and the range RD2of the second permanent magnet391b, the force (second tracking force: Ft2) occurs in the direction of +X (or the direction of −X), which is the same direction as the first tracking force.

In the present embodiment, it is set up so that the first tracking force and the second tracking force may serve as the same magnitude mutually, and the movable portion will be driven in the direction of +X (or the direction of −X) as a result according to the current value of the drive current.

In addition, the driving direction (the direction of +X or the direction of −X) is controllable according to the current which flows in each tracking coil.

Moreover, each tracking coil has the magnitude and the configuration according to the driving force needed.

In the present embodiment, it is set up so that the action center of each tracking force and the support center S92(center of inertia Sk) with each line spring may be mostly in agreement, in tracking control at high speed, the movable portion does not rotate in XZ plane.

The first radial tilt coil388aand the second radial tilt coil388bare the coils of the same configuration mostly mutually.

The first radial tilt coil388ais on the +Y side of the lens holder381, and is arranged at the position which counters almost equally to the range RC3and the range RC4of the first permanent magnet391a, as shown inFIG. 59A.

The second radial tilt coil388bis on the −Y side of the lens holder381, and is arranged at the position which counters almost equally to the range RD3and the range RD4of the second permanent magnet391b, as shown inFIG. 59B.

In addition, a part of the coil388aoverlaps a part of the coil384a1and a part of the coil384a2about the Y-axis direction.

Similarly, a part of the coil388boverlaps a part of the coil384a1and a part of the coil384a2about the Y-axis direction.

Moreover, it is connected so that the same drive current may be mutually supplied to the coil388aand the coil388b.

Thereby, when the drive current is supplied to the first radial tilt coil388a, based on the flowing current and the magnetic flux from the range RC3and the range RC4of the first permanent magnet391a, as shown inFIG. 60E, the force (radial tilt force: first Fr1) occurs in +Z direction (or −Z direction).

As shown inFIG. 60F, when the drive current is supplied to the second radial tilt coil388b, based on the flowing current and the magnetic flux from the range RD3and the range RD4of the second permanent magnet391b, the force (second radial tilt force: Fr2) occurs in +Z direction (or −Z direction), which is the same direction as the first radial tilt force.

In addition, as shown inFIG. 61AandFIG. 61B, the point-of-application S88aof the first radial tilt force and the point-of-application S88bof the second radial tilt force are in the equal distance mostly from the support center S92about the Z-axis direction, and the distance Lfs is set up so that the conditions represented by the following formula (1) may be satisfied.

In addition, Lns is the distance of the principal point St of the objective lens360and the support center S92about the Z-axis direction, ktr is the spring modulus of the line spring, and krad is the torsion-spring constant of the line spring.
Lfs=krad/ktr/Lns(1)

In the present embodiment, when the resultant of the first radial tilt force and the second radial tilt force is set to Ftr, the amount Xtr of movement to the tracking direction of the movable portion is represented by the following formula (2).
Xtr=Ftr/ktr(2)

Moreover, the amount X of movement to the tracking direction of the principal-point position of the objective lens360when the movable portion rotates only the include angle theta1in XZ plane is geometrically shown by the following formula (3).
X=−Lnssin theta1=−Lnstheta1  (3)

The angle of rotation theta1of the movable portion is represented by the following formula (4).
theta1=Lfs Ftr/krad  (4)

Then, when the relation of the formula (3) is used, the formula (3) can be rewritten into the following formula (5).
X=−Lns Lfs Ftr/krad  (5)

Furthermore, since it is set up so that the relation of the formula (1) may be satisfied, the formula (5) can be rewritten to the following formula (6).
X=−Ftr/ktr(6)

Therefore, Xtr and X serve as the relation represented by the following formula (7).
Xtr+X=0  (7)

That is, in order for the movable portion itself to move in the direction contrary to the move direction of the principal-point position in the amount of the same movements even if the principal-point position of the objective lens360moves by the rotation of the movable portion as shown inFIG. 61C, by the tilt control, the principal-point position of the objective lens will not almost change as a result.

In addition, the angle of rotation of the movable portion can be controlled by the magnitude of the current which flows in each coil for radial tilts, and the rotational polarity can be controlled by the polarity of the current which flows in each coil for radial tilts.

Moreover, each coil for radial tilts has the magnitude and the configuration according to the driving force needed.

A description will be given of the operation of the optical pickup device323.

The optical pickup device323is provided in the optical disk drive320so that the Z-axis direction and the tangential direction of the perpendicular to the record side of the optical disk315direction of the track may correspond with the Y-axis direction.

That is, the X-axis direction turns into the tracking direction, and the Z-axis direction turns into the focusing direction.

After the light beam which acts in the direction of +X from the light source unit351serves as the parallel light with the coupling lens352, which is incident to the beam splitter354.

It is reflected in +Z direction by the starting mirror356, and the light beam from the beam splitter354is incident to the focusing system11through the opening of the housing371and the opening of the base plate385.

The light beam incident to the focusing system371is inputted to the objective lens360through the through hole of the lens holder381, and it is focused onto the recording surface of the optical disk315as a minute light spot by the objective lens360.

The reflected light from the recording surface of the optical disk315is converted by the objective lens360into a return light beam which is the parallel light again, and through the opening of the base plate385and the opening of the housing371it is incident to the mirror356.

The return light beam incident to the starting mirror356is reflected in the direction of −X and it is incident to the beam splitter354.

The return light beam which branches in the direction of −Y by the beam splitter354is passed through the detection lens358and the cylindrical lens357, and it is received by the photodetector359.

Each light-receiving component which constitutes the photodetector359outputs the current signal according to the amount of the received light to the reproduction signal processing circuit328, respectively.

Next, a description will be given of the control processing of the position and attitude of the objective lens360in the optical disk drive320.

First, the focus control in the optical disk drive320will be explained.

1. After the reproduction signal processing circuit328changes the output signal of the photodetector359into the voltage signal by the first I/V amplifier328a, it detects the focusing error signal by the servo signal detector328b, and outputs the detected signal to the servo controller333.

2. The servo controller333generates the focal control signal for correcting the focal gap based on the focusing error signal, and outputs the signal to the motor driver327.

3. The motor driver327outputs the drive current for focal control corresponding to the focal control signal to the optical pickup device323.

4. In the optical pickup device323, the drive current for the focal control from the motor driver327is inputted into the predetermined input terminal of the board393, and is supplied to each focusing coil through the line spring392a3and the line spring392b3.

5. When the drive current flows through each focusing coil, the driving force according to the magnitude of the current and the polarity of the current will occur, and the movable portion will be driven in the direction of the focus control accordingly.

As a result, the objective lens360shifts in the direction of the focus control, and the focal gap is corrected.

The tracking control in the optical disk drive320will now be explained.

1. After the reproduction signal processing circuit328changes the output signal of the photodetector359into the voltage signal by the first I/V amplifier328a, it detects the tracking error signal by the servo signal detector328b, and outputs it to the servo controller333.

2. The servo controller333generates the tracking control signal for correcting the track gap based on the tracking error signal, and outputs it to the motor driver327.

3. The motor driver327outputs the drive current for tracking control corresponding to the tracking control signal to the optical pickup device323.

4. In the optical pickup device323, the drive current for the tracking control from the motor driver327is inputted into the predetermined input terminal of the board393, and is supplied to each tracking coil through the line spring392a2and the line spring392b2.

5. When the drive current flows through each tracking coil, the driving force according to the magnitude of the current and the polarity of the current will occur, and the movable portion will be driven in the tracking direction accordingly.

As a result, the objective lens360shifts to the tracking direction, and the track gap is corrected.

The tilt control in the optical disk drive320will now be explained.

1. After the reproduction signal processing circuit328changes the output signal of the tilt sensor342into the voltage signal by the second I/V amplifier328f, it detects the information about the media tilt by the tilt detector328g, and outputs it to the servo controller333as the tilt information signal.

2. The servo controller333generates the radial tilt compensation signal for correcting the radial tilt based on the tilt information signal, and outputs it to the motor driver327.

3. The motor driver327outputs the drive current for radial tilt control corresponding to the radial tilt compensation signal to the optical pickup device323.

4. In the optical pickup device323, the drive current for the radial tilt control from the motor driver327is inputted into the predetermined input terminal of the board393, and is supplied to the radial tilt coils through the line spring392a1and the line spring392b1.

5. When the drive current flows through each radial tilt coil, the driving force according to the magnitude of the current and the polarity of the current will occur, and the movable portion will be inclined in XZ plane.

As a result, the objective lens360is rotated in XZ plane, and the radial tilt is corrected.

Next, the processing operation in the case of accessing the optical disk315using the optical disk drive320will be explained.

First, the recording processing of the optical disk drive320will be explained.

When the command of the record request is received from the host, the CPU340notifies the receipt of the command of the record request to the reproduction signal processing circuit328while outputting the control signal for controlling rotation of the spindle motor322based on the specified record rate to the motor driver327.

Moreover, the CPU340directs the accumulation to the buffer RAM334of the user data received from the host to the buffer manager337.

When the rotation of the optical disk315reaches the predetermined linear velocity, the focal control, tracking control and tilt control (which will be generically called the position attitude control) will be performed by the CPU340.

In addition, the position attitude control is performed at any time until the record processing is completed.

And the reproduction signal processing circuit328acquires ADIP information based on the output signal of the photodetector359, and notifies it to the CPU340.

In addition, the reproduction signal processing circuit328acquires ADIP information for every predetermined timing until the record processing is completed, and notifies it to the CPU340.

The CPU340outputs the signal which controls the seeking motor to the motor driver327so that the optical pickup body301is located at the start point where it performs writing to the optical disk based on ADIP information.

When the notice that the amount of user data accumulated at the buffer RAM334exceeds the predetermined value is received from the buffer manager337, the CPU340directs generation of the signal for writing to the encoder325.

When the CPU340determines that the writing position of the optical pickup body301is the start point based on ADIP information, it will be notified to the encoder325.

Accordingly, the user data are recorded on the optical disk315through the encoder325, the laser control circuit324and the optical pickup device323.

The reproduction processing of the optical disk drive320will now be explained.

When the command of the reproduction request is received from the host, the CPU340outputs to the motor driver327the control signal for controlling rotation of the spindle motor322based on the reproduction rate. At the same time, the CPU340notifies to the reproduction signal processing circuit328that the command of the reproduction request is received.

When the rotation of the optical disk315reaches the predetermined linear velocity, the position attitude control will be performed by the CPU340.

In addition, the position attitude control is performed at any time until the reproduction is completed.

And the reproduction signal processing circuit328acquires ADIP information based on the output signal of the photodetector359, and notifies it to the CPU340.

In addition, the reproduction signal processing circuit328acquires ADIP information for every predetermined timing until the reproduction is completed, and it notifies it to the CPU340.

The CPU340outputs the signal which controls the seeking motor to the motor driver327so that the optical pickup body301is located at the start point for the reading on the optical disk based on ADIP information.

When the CPU340determines that the reading position of the optical pickup body301is the start point on the optical disk based on ADIP information, it will notify it to the reproduction signal processing circuit328.

And after the reproduction signal processing circuit328detects the RF signal based on the output signal of the photodetector359and performs recovery processing, error-correction processing, etc., it is accumulated to the buffer RAM334as reproduction data.

The buffer manager337transmits to the host through the interface338, when the reproduction data accumulated at the buffer RAM334are assembled as sector data.

As is apparent from the above description, the tilt detection unit is constituted by the tilt sensor342and the tilt detector328gin the optical disk drive of the present embodiment.

Moreover, the processing mechanism is realized by the program performed by the CPU340, the reproduction signal processing circuit328, and the CPU340.

According to the present embodiment, in the tilt control, the principal point of the objective lens does not need to be located near the rotation axis of the movable portion, and the degree of freedom in the design of each coil increases, and it is possible to acquire the required driving force easily. Therefore, it is possible to raise the servo control performance.

According to the present embodiment, it is possible to drive the objective lens with sufficient accuracy at high speed.

Moreover, according to the optical pickup device of the present embodiment, the rapid response and focal control of the objective lens, the tracking control, and the radial tilt control can be performed efficiently.

The optical spot of the predetermined configuration is stabilized with sufficient accuracy in the predetermined position of the optical disk, and is formed in it, and it is possible for the optical pickup device to output the signal, including the information required for the position control of the objective lens, with sufficient accuracy.

Moreover, according to the optical disk drive of the present embodiment, it is possible for the optical pickup device to be stabilized with sufficient accuracy and to perform the high-speed access which includes reproduction, erasing and recording of the information storage medium.

In the foregoing embodiment, the case where the frequency of the drive signal supplied to the tilt drive unit is comparatively low, or the case where the occurrence of cross action by tilt operation in the elastic range in the displacement sensibility property of the optical pickup device is suppressed at a very low level is described.

When the frequency of the drive signal outputted to the optical pickup device is high, it is possible to set up such that the occurrence of cross action by tilt operation may be suppressed at the very low level in the inertia range in the displacement sensibility property of the optical-pickup device.

In this case, it will set up so that the conditions related to the distance (referred to as Lfg) of the point of application of each radial tilt force and the center of inertia Sk of the movable portion about the Z-axis direction, which are indicated by the following formula (8), may be satisfied.
Lfg=Irad/m/Lng(8)

In the above formula (8), Lng is the distance of the principal point St of the objective lens360and the center of inertia Sk concerning the Z-axis direction, Irad is the moment of inertia of the movable portion, and m is the mass of the movable portion.

In addition, in the preferred embodiment, the support center S92and the center of inertia Sk are mostly in agreement, or Lng=Lns. However, the present invention is is not limited to this embodiment, and the support center S92may differ from the center of inertia Sk.

The reason will now be explained.

The acceleration alpha1of movement to the tracking direction of the movable portion by each radial tilt force is shown by the following formula (9).
alpha1=Ftr/m(9)

The amount X2of movement to the tracking direction of the principal-point position of the objective lens360when the movable portion rotates only by the include angle theta2in XZ plane is shown by the following formula (10).
X2=−Lngsin(theta2)=−Lng(theta2)  (10)

Then, the acceleration alpha2to the tracking direction of the principal-point position is shown by the following formula (11).
alpha2=−Lng(theta2″)  (11)

In the above formula (11), theta2″ is the angular acceleration of the movable portion.

The angular-acceleration theta2″ has the relation of the following formula (12).
theta2″=Lfg(Ftr/Irad)  (12)

Then, if the relation of the formula (12) is used, the above formula (11) can be rewritten to the following formula (13).
alpha2=−Lng(Lfg(Ftr/Irad))  (13)

In the present embodiment, it is set up so that the relation of the above formula (8) may be satisfied, and the above formula (13) can be further rewritten to the following formula (14).
alpha2=−Ftr/m(14)

Therefore, alpha1and alpha2satisfy the relation represented by the following formula (15).
alpha1+alpha2=0  (15)

Namely, even if the principal-point position of the objective lens360moves by the rotation of the movable portion, in order for the movable portion to move in the direction contrary to the move direction of the principal-point position with the same acceleration, the principal-point position of the objective lens by the tilt control will not almost change as a result.

In addition, when the frequency band of the drive signal is wide, it is possible to satisfy the conditions shown by the following formula (16).
Irad/m=krad/ktr(16)

That is, it is possible to make the primary resonance frequency in the tracking direction of the movable portion, and the primary resonance frequency in rotation in XZ plane mostly in agreement.

In addition, when the above conditions cannot be satisfied by the restrictions on the design, or when there is a possibility of having the bad influence on the operation of the optical disk drive when the above conditions are satisfied, it is possible to adopt an intermediate value between Lfg and Lfs.

Moreover, in the preferred embodiment, the case where the radial tilt coils (first radial tilt coil388aand second radial tilt coil388b) are used as a pair of radial tilt coils is explained. However, the present invention is not limited to this embodiment.

As shown in FIG.62A–FIG. 62D, it is possible to add the two pairs of radial tilt coils (388a1,388a2,388b1,388b2) as a coil for generating the couple moment.

The two pairs of radial tilt coils (388a1,388a2,388b1,388b2) are the coils of the same configuration mostly with the focusing coils.

The laminating of the radial tilt coil388a1and the first focusing coil384a1is mutually carried out to the Y-axis direction, and they form the first laminating coil SC1.

The laminating of the radial tilt coil388a2and the second focusing coil384a2is mutually carried out to the Y-axis direction, and they form the second laminating coil SC2.

The laminating of the radial tilt coil388b1and the third focusing coil384b1is mutually carried out to the Y-axis direction, and they form the third laminating coil SC3.

The laminating of the radial tilt coil388b2and the fourth focusing coil384b2is mutually carried out to the Y-axis direction, and they form the fourth laminating coil SC4.

As shown inFIG. 63A, the first laminating coil SC1is on the +Y side of the lens holder381, and is arranged in the position which counters almost equally to the range RC1and the range RC3of first permanent magnet391a.

The second laminating coil SC2is on the +Y side of the lens holder381, and is arranged in the position which counters almost equally to the range RC2and the range RC4of first permanent magnet391a.

As shown inFIG. 63B, the third laminating coil SC3is on the −Y side of the lens holder381, and is arranged in the position which counters almost equally to the range RD1and the range RD3of second permanent magnet391b.

The fourth laminating coil SC4is on the −Y side of the lens holder381, and is arranged in the position which counters almost equally to the range RD2and the range RD4of second permanent magnet391b.

In addition, the focusing coils need a larger driving force than the radial tilt coils, and the focusing coils are arranged to the permanent magnet side so that the strong magnetic flux against the focusing coils may occur.

Moreover, it is connected by each coil for radial tilts so that the respectively same drive current may be supplied.

Thereby, if the drive current is supplied to the coil388a1for radial tilts, as shown inFIG. 64A, based on the flowing current and the magnetic flux from the range RC1and the range RC3of the first permanent magnet391a, the force (third radial tilt force: Fr3) will occur in −Z direction (or +Z direction).

If the drive current is supplied to the coil388a2for radial tilts, based on the flowing current and the magnetic flux from the range RC2and the range RC4of the first permanent magnet391a, the force (fourth radial tilt force: Fr4) will occur in +Z direction (or −Z direction), which is opposite to the direction of the third radial tilt force.

If the drive current is supplied to the coil388b1for radial tilts, as shown inFIG. 64B, based on the flowing current and the magnetic flux from the range RD1and the range RD3of the second permanent magnet391b, the force (fifth radial tilt force: Fr5) will occur in −Z direction (or +Z direction), which is the same direction as the third radial tilt force.

If the drive current is supplied to the coil388b2for radial tilts, based on the flowing current and the magnetic flux from the range RD2and the range RD4of the second permanent magnet391b, the force (sixth radial tilt force: Fr6) will occur in +Z direction (or −Z direction), which is opposite to the direction of the third radial tilt force.

As the result, the couple moment (referred to as Mg) to rotate the movable portion in XZ plane will occur.

In this case, what is necessary is just to arrange each radial tilt coil so that the ratio of the couple moment Mg and the force Ftr may satisfy the following formula (17).
Ftr/Mg=Lns/krad{(1/ktr)−(Lns(Lfs/krad))}  (17)

The reason is explained below.

The amount X3of movement to the tracking direction of the principal-point position of the objective lens360when the movable portion rotates only by the include angle theta3in XZ plane is represented by the following formula (18).
X3=−Lns(sin(theta3))=−Lns(theta3)  (18)

In this case, the angle of rotation theta3in XZ plane of the movable portion is the addition value of the rotation by the couple moment Mg and the rotation by Ftr, as shown in the following formula (19).
theta3=Mg/krad+Lfs(Ftr/krad)  (19)

Then, if the relation of the formula (19) used, the above formula (18) can be rewritten to the following formula (20).
X3=−Lns(Mg/krad)−Lns(Lfs(Ftr/krad))  (20)

Furthermore, since it is set up so that the relation of the formula (17) may be satisfied, the above formula (20) can be rewritten to the following formula (21).
X3=−Ftr{(1/ktr)−(Lns(Lfs/krad))}−Lns(Lfs(Ftr/krad))=−Ftr/ktr(21)

Therefore, Xtr and X3satisfy the relation represented by the following formula (22).
Xtr+X3=0  (22)

That is, even if the principal-point position of the objective lens360moves by the rotation of the movable portion, in order for the movable portion to move in the direction contrary to the move direction of the principal-point position in the amount of the same movement, the principal-point position of the objective lens by the tilt drive will not almost change as a result.

In addition, the direction of the rotation can be controlled by the polarity of the flowing current of each radial tilt coil.

Moreover, each coil for radial tilts has the magnitude and the configuration according to the driving force needed.

In this case, what is necessary is just to arrange each coil for radial tilts so that the ratio of the couple moments Mg and Ftr may satisfy the following formula (23) when the frequency of the drive signal is high.
Ftr/Mg=Lng/{Irad(1/m−Lng(Lfg/Irad))}  (23)

The reason is explained below.

The acceleration alpha1of movement to the tracking direction of the movable portion by the driving force Ftr is shown by the formula (9).

Moreover, the amount X4of movement to the tracking direction of the principal-point position of the objective lens360when the movable portion rotates only by the include angle theta4in XZ plane is shown by the following formula (24).
X4=−Lng(sin(theta4))=−Lng(theta4)  (24)

The acceleration alpha4to the tracking direction of the principal-point position is shown by the following formula (25).
alpha4=−Lng(theta4″)  (25)

In the above formula (25), theta4″ is the angular acceleration of the movable portion.

The angular-acceleration theta4″ is the addition value of the angular acceleration by the couple moment Mg and the angular acceleration by the driving force Ftr, as shown in the following formula (26).
theta4″=Mg/Irad+Lfg(Ftr/Irad)  (26)

Then, if the relation of the formula (26) is used, the above formula (25) can be rewritten to the following formula (27).
alpha4=−Lng(Mg/Irad)−Lng(Lfg(Ftr/Irad))  (27)

Furthermore, since it is set up so that the relation of the formula (23) may be satisfied, the above formula (27) can be further rewritten to the following formula (28).

Therefore, alpha1and alpha4satisfy the relation represented by the following formula (29).
alpha1+alpha4=0  (29)

That is, even if the principal-point position of the objective lens360moves by the rotation of the movable portion, in order for the movable portion to move in the direction contrary to the move direction of the principal-point position with the same acceleration, the principal-point position of the objective lens by the tilt control will not almost change as a result.

In addition, in the case where the frequency band of the drive signal is wide, at the time when the conditions are satisfied but there is a possibility of having the bad influence on the operation of the optical disk drive, or at the time when the conditions of the formula (23) cannot be satisfied by the restrictions on the design, what is necessary is that Ftr/Mg satisfy the conditions represented by the following formula (30).
Lns/krad{(1/ktr)−Lns(Lfs/krad)}<Ftr/Mg<Lng/Irad{(1/m)−Lng(Lfg/Irad)}  (30)

Moreover, in the present embodiment, as shown in FIG.65A–FIG. 65D, the radial tilt coil388may be provided around the perimeter of the lens holder381′ in XY plane as a coil for generating the couple moment.

As shown inFIG. 66A, the radial tilt coil388is arranged on the −Y side of the lens holder381at the position which counters the range RC3and the range RC4of the first permanent magnet391a. As shown inFIG. 66B, it is arranged on the +Y side of the lens holder381at the position which counters the range RD3and the range RD4of the second permanent magnet391b.

As shown inFIG. 67A, when the drive current is supplied to the radial tilt coil388, the force (seventh radial tilt force: Fr7) occurs in −Z direction (or +Z direction) based on the current flowing through the radial tilt coil388and the magnetic flux from the range RC3of the first permanent magnet391a. At the same time, based on the same current and the magnetic flux from the range RC3, the force (eighth radial tilt force: Fr8) occurs in +Z direction (or −Z direction), which is opposite to the direction of the seventh radial tilt force.

Moreover, as shown inFIG. 67B, based on the current flowing through the radial tilt coil388and the magnetic flux from the range RD3of the second permanent magnet391b, the force (ninth radial tilt force: Fr9) occurs in −Z direction (or +Z direction), which is the same direction as the seventh radial tilt force. At the same time, based on the same current and the magnetic flux from the range RD4, the force (tenth radial tilt force: Fr10) occurs in +Z direction (or −Z direction), which is opposite to the direction of the ninth radial tilt force.

As the result, the couple moment (referred to as Mg2) to rotate the movable portion in XZ plane is generated.

In this case, what is necessary is just to arrange each radial tilt coil so that the ratio of the driving force Ftr to the couple moment Mg2may satisfy the following formula (31).
Ftr/Mg2=Lns/krad{(1/ktr)−(Lns(Lfs/krad))}  (31)

Moreover, in the present embodiment, the pair of the radial tilt coils for generating the couple moment with which each magnet range is countered except the part extending in the Z-axis direction may be arranged additionally.

Moreover, in the present embodiment, the case where the surfaces of each permanent magnet which confront each other mutually are divided into the four equal ranges, respectively. However, the present invention is not limited to this embodiment.

For example, as shown inFIG. 68AandFIG. 68B, it is possible to divide each surface into the two ranges by the magnetization limits (EP, FP) of the Z-axis direction.

That is, the third magnet391a′ is used instead of first permanent magnet391a, and the fourth magnet391b′ may be used instead of being the second permanent magnet391b.

In the present embodiment, as shown inFIG. 68A, let the range RE1and the range on the side of +X be the ranges RE2for the range on the side of −X of the magnetization limits EP in third magnet391a′. In addition, the respective ranges have the reversed polarity mutually.

Moreover, as shown inFIG. 68B, let the range RF1and the range on the side of +X be the ranges RF2for the range on the side of −X of the magnetization limits FP in the fourth magnet391b′. In addition, the respective ranges have the reversed polarity mutually.

In this case, as shown in FIG.69A–FIG. 69D, the radial tilt coil388a′ is used instead of the first radial tilt coil388a, and the radial tile coil388b′ is used instead of the second radial tilt coil388b.

As shown inFIG. 70A, the radial tilt coil388a′ is arranged, except for the part extending in the X-axis direction, at the position to equally confront the range RE1and the range RE2of the third magnet391a′.

As shown inFIG. 70B, the radial tilt coil388b′ is arranged in the position to equally confront the range RF1and the range RF2of the fourth magnet391b′, except for the part extending in the X-axis direction.

When the drive current is supplied to the radial tilt coil388a′, as shown inFIG. 71A, the force (11th radial tilt force Fr11, 12th radial tilt force: Fr12) of +X direction (or −X direction) occurs based on the current flowing through the radial tilt coil388a′ and the magnetic flux from the range RE1and the range RE2of the third permanent magnet391a′. At the same time, the force (13th radial tilt force: Fr13) of +Z direction (or −Z direction) and the force (14th radial tilt force: Fr14) of −Z direction (or +Z direction) occur.

As shown inFIG. 71B, when the drive current is supplied to the radial tilt coil388b′, the force (15th radial tilt force: Fr15, 16th radial tilt force: Fr16) occurs in the direction of +X (or the direction of −X) based on the current flowing through the radial tilt coil388b′ and the magnetic flux from the range RF1and the range RF2of the fourth permanent magnet391b′. At the same time, the force (17th radial tilt force: Fr17) of the +Z direction (or −Z direction) and the force (18th radial tilt force: Fr18) of the −Z direction (or +Z direction) occur.

In this case, what is necessary is just to arrange each radial tilt coil so that the ratio of the driving force Ftr2of the X-axis direction by Fr11, Fr12, Fr15and Fr16to the couple moment Mg3by Fr13, Fr14, Fr17and Fr18may satisfy the following formula (32).
Ftr2/Mg3=Lns/krad{(1/ktr)−(Lns(Lfs/krad))}  (32)

In addition, when the frequency of the drive signal is high, and when the frequency band is wide, the approach that is the same as described above can be used.

Moreover, as shown inFIG. 72AandFIG. 72B, it is possible to use the permanent magnets395aand395bwith which the magnitude of each range differs mutually.

As the surface on the side of −Y of the permanent magnet395ais shown inFIG. 72A, it is divided into the two ranges by the magnetization limits GP of the Z-axis direction, and each range is further divided into the L-shaped range and the rectangular range.

In the present embodiment, the rectangular range on the side of −X of the magnetization limits GP is indicated by the range RG1, and the L-shaped range on the same side is indicated by the range RG2.

The rectangular range on the side of +X of the magnetization limits GP is indicated by the range RG3, and the L-shaped range on the same side is indicated by the range RG4.

And the range RG1and the range RG2have the reversed polarity mutually, and the range RG3and the range RG4have the reversed polarity mutually. Moreover, the range RG1is smaller than the range RG2, and the range RG3is smaller than the range RG4.

As shown inFIG. 72B, the surface on the side of +Y of the permanent magnet395bis divided into the two ranges by the magnetization limits HP of the Z-axis direction, and each range is further divided into the L-shaped range and the rectangular range.

In the present embodiment, the rectangular range on the side of −X of the magnetization limits HP is indicated by the range RH1, and the L-shaped range on the same side is indicated by the range RH2. The rectangular range on the side of +X of the magnetization limits HP is indicated by the range RH3, and the L-shaped range on the same side is indicated by the range RH4.

And the range RH1and the range RH2have the reversed polarity mutually, and the range RH3and the range RH4have the reversed polarity mutually. Moreover, the range RH1is smaller than the range RH2, and the range RH3is smaller than the range RH4.

In this case, as shown inFIG. 73A, the first tracking coil382ais arranged at the position which equally counters the range RG2and the range RG4of the permanent magnet395a. As shown inFIG. 73B, the second tracking coil382bis arranged at the position which equallt counters the range RH2and the range RH4of the permanent magnet395b.

As shown inFIG. 73A, the first focusing coil384a1is arranged at the position where the range RG1and the range RG2of the permanent magnet395acounter equally to the part which adjoins the Z-axis direction, and the second focusing coil384a2is arranged at the position where the range RG3and the range RG4of the permanent magnet395acounter almost equally to the part which adjoin the Z-axis direction.

Moreover, as shown inFIG. 73B, the third focusing coil384b1is arranged at the position where the range RH1and the range RH2of the permanent magnet395bcounter almost equally to the part which adjoins the Z-axis direction. The fourth focusing coil384b2is arranged at the position where the range RH3and the range RH4of the permanent magnet395bcounter almost equally to the part which adjoins the Z-axis direction.

As shown inFIG. 73A, the radial tilt coil388a1is arranged at the position where about two thirds of this coil counters the range RG2of the permanent magnet395aand the remainder of this coil counters the range RG1. The radial tilt coil388a2is arranged at the position where about two thirds of this coil counters the range RG4and the remainder of this coil counters the range RG2.

As shown inFIG. 73B, the radial tilt coil388b1is arranged at the position where two thirds of this coil counters the range RH2of the permanent magnet395band the remainder thereof counters the range RH1. The radial tilt coil388b2is arranged at the position where two thirds of this coil counters the range RH4and the remainder thereof counters the range RH3.

As shown inFIG. 74AandFIG. 74B, when the drive current is supplied to each radial tilt coil, the driving force to move the movable portion to the X-axis direction and the couple moment to rotate the movable portion in XZ plane occur.

Therefore, the movement of the principal-point position of the objective lens generated by the radial tilt drive can be controlled by arranging each radial tilt coil so that the above-mentioned conditions related to the ratio of the driving force and the couple moment may be satisfied.

Furthermore, as shown inFIG. 75AandFIG. 75B, the permanent magnets396aand396bhaving respective ranges with the shape of a triangle may be used instead.

As shown inFIG. 75A, the surface on the side of −Y of the permanent magnet396ais divided into the two ranges by the magnetization limits IP of the Z-axis direction, and each range is further divided into the two triangule ranges.

In the present embodiment, the triangle range on the −X side of the magnetization limits IP which makes the magnetization limits IP one side of the triangle range is indicated by the range RI2. The other triangle range is indicated by the range RI1. The triangle range on the +X side of the magnetization limits IP which makes the magnetization limits IP one side of the triangle range is indicated by the range RI4. The other triangle range is indicated as the range RI3. In addition, the triangle ranges which adjoin each other have the reversed polarity mutually.

As shown inFIG. 75B, the surface on the side of +Y of permanent magnet396bis divided into the two ranges by the magnetization limits JP of the Z-axis direction, and each range is further divided into the two triangle ranges.

In the present embodiment, the triangle range on the −X side of the magnetization limits JP which makes the magnetization limits JP one side of the triangle range is indicated by the range RJ2. The other triangle range is indicated by the range RJ1. The triangle range on the +X side of the magnetization limits JP which makes the magnetization limits JP one side of-the triangle range is indicated by the range RJ4. The other triangle range is indicated as the range RJ3. In addition, the triangle ranges which adjoin each other have the reversed polarity mutually.

In this case, as shown inFIG. 76A, the first tracking coil382ais arranged at the position which counters almost equally to the range RI2and the range RI4of the permanent magnet396a. As shown inFIG. 76B, the second tracking coil382bis arranged at the position which counters almost equally to the range RJ2and the range RJ4of the permanent magnet396b.

As shown inFIG. 76A, the first focusing coil384a1is arranged at the position which counters almost equally to the range RI1and the range RI2of the permanent magnet396a. The second focusing coil384a2is arranged at the position which counters almost equally to the range RI3and the range RI4of the permanent magnet396a.

Moreover, as shown inFIG. 76B, the third focusing coil384b1is arranged at the position which counters almost equally to the range RJ1and the range RJ2of the permanent magnet396b, and the fourth focusing coil384b2is arranged at the position which counters almost equally to the range RJ3and the range RJ4of the permanent magnet396b.

As shown inFIG. 76A, the radial tilt coil388a1is arranged at the position where about two thirds of this coil counter the range RI1of the permanent magnet396aand the remainder thereof counters the range RI2. The radial tilt coil388a2is arranged at the position where about ⅔ of this coil counters the range RI3and the remainder counters the range RI4.

As shown inFIG. 76B, the radial tilt coil388b1is arranged at the position where about two thirds of this coil counters the range RJ1of the permanent magnet396band the remainder counters the range RJ2. The radial tilt coil388b2is arranged at the position where about two thirds of this coil counter the range RJ3and the remainder counters the range RJ4.

As shown inFIG. 77AandFIG. 77B, when the drive current is supplied to each radial tilt coil, the driving force to move the movable portion to the X-axis direction and the couple momemnt to rotate the movable portion in XZ plane occur.

Therefore, the movement of the principal-point position of the objective lens generated by the radial tilt drive can be controlled by arranging each radial tilt coil so that the above-mentioned conditions related to the ratio of the driving force and the couple moment may be satisfied.

Moreover, in the present embodiment, the case where the tilt sensor is arranged apart from the optical pickup device is described. However, the present invention is not limited to this embodiment. It is possible that the tilt sensor be arranged within the optical pickup device.

It is possible to add the tilt detectors328, and the circuit which performs the same processing to the optical pickup device. In the optical pickup device of such embodiment, the signal with which the influence of the radial tilt is removed will be stably be outputted.

Moreover, as for the arrangement of the range in the permanent magnet, it is not limited to the above-described embodiment. It is adequate that the turning effort which rotates the movable portion around the rotation axis of the Y-axis direction, and the translation force which offsets the movement of the principal point of the objective lens about the X-axis direction accompanying the rotation act on the movable portion almost simultaneously with the tilt control.

Moreover, as for the composition and the arrangement position of the radial tilt coils, it is not limited to the above-described embodiment. It is adequate that the turning effort which rotates the movable portion around the rotation axis of the Y-axis direction, and the translation force which offsets the movement of the principal point of the objective lens about the X-axis direction accompanying the rotation act on the movable portion almost simultaneously with the tilt control.

Moreover, in the above-described embodiment, the case where the information storage medium based on the specification of the DVD system is used as the optical disk315is described. However, the present invention is not limited to this embodiment, and it is possible to use an information storage medium based on the specification of the CD (compact disc) system or a laser disk.

The present invention is applicable to any information storage medium to which a light beam is focused in order to carry out at least reproduction of information from the storage medium among the functions of recording, reproduction and elimination.

As for the light source which outputs the light beam, not only the light source that outputs a light beam whose wavelength is 660 nm but also the light source that outputs a light beam whose wavelength is 405 nm or the light source that outputs a light beam whose wavelength is 780 nm may be used.

Moreover, in the above-described embodiment, the case where a single light sources is used is described. However, the present invention is not limited to this embodiment, and it is possible to use a plurality of light sources. In such a case, it is possible to use a multiple light-source unit including any of the light source that outputs the light beam whose wavelength is 405 nm, the light source that outputs the light beam whose wavelength is 660 nm, and the light source that outputs the light beam whose wavelength is 780 nm.

Further, the present invention is based on Japanese priority applications No. 2002-165616, filed on Jun. 6, 2002; No. 2002-198442, filed on Jul. 8, 2002; No. 2002-297166, filed on Oct. 10, 2002; and No. 2002-334417, filed on Nov. 18, 2002, the entire contents of which are hereby incorporated by reference.