JP2000235721A - Objective lens driving device and seeking device for optical pickup device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce power consumption and heat generation by improving driving efficiency, and to make the driving of a movable part such as an objective lens holder member or a carriage smooth and stabilized. SOLUTION: In the case of performing recording/reproducing by using a certain medium, electricity is conducted such that two element coils 3a and 3b are wired in series to make one coil, and an objective land holding member 2 is driven by magnetic force. In addition, in the case of performing recording/ reproducing by using another medium, switching is made by a switch to energize only the element coil 3b, and the objective lends holding member 2 is driven. Thus, since by switching between the different element coils 3a and 3b to be energized, electricity is conducted only to the element coil of a range necessary for driving a different medium, power consumption and heat generating are reduced without supplying any current to an excessive coil part during driving. Further, since the linear density of the coil is increased in a space equal to that of conventional device, high propelling force is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an objective lens driving device and a seek device mounted on an optical pickup device for recording / reproducing on / from an optical disk.

[0002]

2. Description of the Related Art FIG. 10 is a partial sectional view for explaining a schematic configuration of a main part of a conventional moving magnet type objective lens driving device. In FIG. 10, a movable member for holding an objective lens 1 is shown. Objective lens holding member 2
Is elastically supported by one end of two wire springs 5 (a total of four wires on both sides).
A magnet 8 magnetized in a direction perpendicular to the focusing direction and the tracking direction is fixed to the side surface of the. The other end of the wire spring 5 is connected to a fixing member 6 attached to a base 7.
It is fixed to.

A focusing coil 3 wound around the yoke 9 around a yoke 9, which is a coil support, is provided upright in the focusing direction in the vicinity of the surface of the magnet 8 so as to sandwich the objective lens holding member 2. A tracking coil 4 wound outside the focusing coil 3 in the tracking direction (perpendicular to the paper surface) is fixed to the base 7 (only the left coil is shown in cross section in the figure). Either the focusing coil 3 or the tracking coil 4 may be wound outside.

When a current is applied to the focusing coil 3, a driving force in the focusing direction is generated by a magnetic force generated by the current in the tracking direction close to the magnet 8 and the magnetic field of the magnet 8. When a current is applied to the tracking coil 4, a driving force in the tracking direction is generated by a magnetic force generated by the current in the focusing direction close to the magnet 8 and the magnetic field of the magnet 8.

[0005] When one objective lens is used for different types of media, the position (working distance) at which the light is focused on the media may be different. Also, different media have different movement ranges due to differences in the amount of surface shake (for example, FIG.
In the range of A and B). Therefore, when recording / reproducing a certain medium, the moving range used only for another medium is not used, so that useless space is generated. For this reason, when the movement range is different, it is more advantageous to supply a current only to a necessary portion.

Further, since the magnetic field generated by the coil has an intensity distribution and the magnetic field intensity is weak at both ends of the coil, the movable member (the objective lens holding member 2 in FIG. 10) is located at both ends of the moving range. When the driving force is generated using the magnetic field at the end, the driving force is reduced as compared with when the movable member is located at the center of the movement range, and a gain variation occurs. Furthermore, when the movable member is located at the end of the movement range, the center of the driving force is deviated from the center of the movable member, so that a moment is generated in the movable member, resulting in an increase in tilt.

Therefore, regardless of the position of the movable member,
It is desirable that the strength and distribution of the magnetic field due to the coil affecting the magnet fixed to the movable member be always equal.

Japanese Patent Application Laid-Open No. HEI 6-215384 describes a seek mechanism of an optical pickup device in which a fixed part coil is constituted by a plurality of element coils. FIG. 11 is a structural view showing a planar state for explaining a seek mechanism of an optical pickup device described in Japanese Patent Application Laid-Open No. 6-215384, in which an objective lens 10 for forming a light spot on an optical disk D is focused at least. A carriage 11 provided with an objective lens moving device that moves in a direction moves along a seek rail 12. The driving force at that time is a driving coil composed of a permanent magnet 13 fixed to the carriage 11 and a plurality of element coils 14a to 14d opposed to the permanent magnet 13 and arranged in parallel to the moving direction of the carriage 11. It is generated by a seek motor constituted by.

The moving magnet system as described above has an advantage that the number of wires for the carriage 11, which is a movable member, can be reduced. Further, in the configuration shown in FIG. 11, power saving can be realized by dividing the coil.

[0010]

However, in the configuration of the seek mechanism of the optical pickup device described in the above-mentioned conventional Japanese Patent Application Laid-Open No. 6-215384, the drive coil 14
The length of each of the plurality of element coils 14a to 14d in the moving direction is set to be longer than the length of the permanent magnet 13 in the moving direction. Carriage 11
There is a problem that when the position is located, the driving force changes.

An object of the present invention is to solve the above-mentioned conventional problems, improve driving efficiency, reduce power consumption and heat generation, and smoothly and stably drive a movable member such as an objective lens holding member or a carriage. It is an object of the present invention to provide an objective lens driving device and a seek device in an optical pickup device which enable the above.

[0012]

In order to achieve the above object, the present invention provides an objective lens holding member which holds an objective lens forming a light spot and has a magnet provided on a side, and an object facing the magnet. An objective lens driving device for an optical pickup device configured to drive the objective lens holding member together with the objective lens in a predetermined direction by supplying a current to the driving coil. A plurality of element coils wound around a support parallel to the driving direction, wherein the driving coils are arranged in series, and only at least one element coil existing within a moving range required for driving is energized. With this configuration, the movable range is cut by appropriately changing the energized element coils according to the media used. Alternatively, by energizing only necessary portions, the linear density of the coil can be increased in a space equivalent to that of a conventional device of this type, and power consumption and heat generation during driving can be suppressed.

Further, the present invention provides an objective lens holding member holding an objective lens forming a light spot and having a magnet on a side portion, and a base member having a driving coil installed facing the magnet. An objective lens driving device in an optical pickup device configured to drive the objective lens holding member together with the objective lens in a predetermined direction by energizing the driving coil, wherein the driving coil is supported in parallel with the driving direction. A plurality of element coils wound around the body are arranged in series, and a means for energizing only at least one element coil close to the magnet during a moving process during driving, With this configuration, energization of the element coil is performed efficiently,
Further, since the driving force in the rotating direction caused by the movement of the objective lens holding member is reduced, the dynamic tilt is reduced, and the change in the driving force (gain variation) caused by the movement is also reduced.

The present invention also provides the driving coil, wherein:
The configuration is such that the total resistance value of the element coils to be energized is always substantially constant. With this configuration, a change in sensitivity can be eliminated, and the driving can be performed smoothly.

Further, according to the present invention, in the drive coil,
The element coils are arranged so as to be symmetrical with respect to a plane perpendicular to the moving direction at the time of the driving. With this configuration, the driving can be performed smoothly and the coils can be configured efficiently. .

According to the present invention, there is further provided a carriage on which an optical component for forming a light spot and an objective lens driving device are mounted, and a carriage provided with a magnet on a side portion thereof, and a driving coil provided to face the magnet. Provided base member,
A seek device in an optical pickup device for driving a carriage in a predetermined direction by energizing the driving coil, wherein a plurality of element coils wound around a support member parallel to the driving direction with respect to the driving coil. Are arranged in series, and during the movement process of driving the carriage,
In the seek device for energizing only the element coils close to the magnet, the length of each element coil in the moving direction is shorter than the length of the magnet in the moving direction. Accordingly, the linear density of the coil can be increased in a space equivalent to that of a conventional device of this type, and power consumption and heat generation can be suppressed. Further, since the driving force in the rotation direction generated by the movement of the carriage is reduced, the dynamic tilt is reduced, and the change in the driving force (gain fluctuation) caused by the movement is also reduced. In addition, since the magnetic field generated by the current of the coil that affects the magnet becomes substantially constant, the carriage is driven smoothly within the moving range.

Further, according to the present invention, in the driving coil,
The configuration is such that the total resistance value of the element coils to be energized is always substantially constant. With this configuration, a change in sensitivity can be eliminated, and the driving can be performed smoothly.

[0018]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a partial cross-sectional view for explaining a schematic structure of a main part of a moving magnet type objective lens driving device for explaining a first embodiment of the present invention. This is the same as the configuration of the device described based on FIG.

In FIG. 1, one side of an objective lens holding member 2 which is a movable member for holding the objective lens 1 is elastically supported by two ends (a total of four on both sides) of one end of a wire spring 5. A magnet 8 magnetized in a direction perpendicular to the focusing direction and the tracking direction is fixed to a side surface of the holding member 2. The other end of the wire spring 5 is fixed to a fixing member 6 attached to a base 7.

The yoke 9 is provided around a yoke 9 as a support, which is erected in the focusing direction in proximity to the surface of the magnet 8 with the objective lens holding member 2 interposed therebetween.
And a tracking coil 4 wound on the outside of the focusing coil 3 in the tracking direction (perpendicular to the paper surface) is fixed to the base 7 (only the left side in FIG. Shown). Either the focusing coil 3 or the tracking coil 4 may be wound outside.

The focusing coil 3 is composed of two element coils 3a and 3b in the present embodiment, and has a range A of the total coil including the element coil 3a and the element coil 3b.
Is a range necessary for moving (driving) the objective lens holding member 2 when a certain medium A is used, and the range B of the element coil 3b is used when another medium B is used. This is a range necessary for moving (driving) 2. Each element coil 3a, 3b is shown in FIG.
Are connected in series as shown in FIG.
, And a switch 20 is provided to switch the ranges A and B of the element coils 3a and 3b to be energized.

Next, the operation of the first embodiment when the objective lens is driven will be described.

As shown in FIG. 3, when recording / reproducing is performed using a certain medium A, both element coils 3a, 3a
b is wired in series and energized so as to form one coil,
As is well known, the objective lens holding member 2 is driven by a magnetic force. When recording / reproducing is performed using another medium, switching is performed by the switch 20 so that only the element coil 3b is energized, and the objective lens holding member 2 is driven by magnetic force.

As described above, the element coils 3a, 3
By switching b, it is possible to set so that the objective lens holding member 2 is moved by energizing only the range necessary for recording / reproducing of different media, so that current flows through an extra coil portion during driving. Power consumption and heat generation can be reduced. Moreover, since the linear density of the coil can be increased in the same space as that of the conventional device, it is possible to increase the thrust.

FIG. 4 is a sectional view showing a schematic configuration of a main part (magnet and coil part) of a moving magnet type objective lens driving device for explaining a second embodiment of the present invention. Members that are the same as those in the embodiment and have the same function are denoted by the same reference numerals.

In the second embodiment, the focusing coil 3 is composed of five element coils 3a to 3e. As shown in FIG. 5, each of the element coils 3a to 3e is wired in series, and a wiring is taken from a connection point of each coil.
Element coils 3a to 3c to be energized by switches 21 and 22
3e can be switched.

In FIG. 4, the servo control of the driving of the objective lens holding member 2 in the focusing direction is performed.
The objective lens holding member 2 moves in the focus direction following the surface deflection of the optical disc D.
Is detected by a position detection sensor (not shown) or the like, and when the objective lens holding member 2 is located on the plus side in the focus direction, the switches 21 and 22 are switched to switch the three element coils 3a and 3 The coil 3b and the element coil 3c are wired in series to form a single coil (see FIG. 6C), and the objective lens holding member 2 is driven by energizing these coils.

Next, when the objective lens holding member 2 has moved to the vicinity of the center in the focusing direction, the switch 2
By switching between 1 and 22, the element coil 3b, the element coil 3c, and the element coil 3d are wired in series to form a single coil (see FIG. 6B), and by energizing these coils, the objective lens is held. The member 2 is driven.

As described above, by sequentially switching the element coils to be energized from FIG. 6C to FIG. 6A depending on the position of the objective lens holding member 2, only the coil portions necessary for driving are energized, No current flows through the first
The same effect as that of the embodiment can be obtained.

As described above, since the element coils to be energized are switched in accordance with the movement of the objective lens holding member 2, the magnetic field strength of the coil received by the magnet, which has conventionally been caused by the change in the position of the objective lens holding member (movable part). Can be reduced. Therefore, a change in the driving force can be reduced, that is, a gain fluctuation can be reduced. Further, by switching the coil, the distribution of the magnetic field by the coil also moves, so that the change in the distribution of the magnetic field received by the movable magnet is reduced, and the deviation between the center of gravity of the objective lens holding member and the center of the driving force can be reduced. Therefore,
The rotational torque that causes the tilt is reduced, and the dynamic tilt of the objective lens can be reduced. These effects become more remarkable as the length of the element coils is shortened and the number of elements is increased (the number of element coils 3a to 3e is not limited to the example in the above embodiment).

Further, by setting the total resistance value of the element coils 3a to 3e which are always energized by moving the objective lens holding member 2, the sensitivity can be kept from changing. Each element coil 3a
If the wire diameters, wire densities, and winding thicknesses are the same, the element coils 3a to 3e are arranged so as to be symmetrical with respect to a plane (C in FIG. 4) perpendicular to the axis in the focusing direction. Thus, the element coils can be selected so that the total resistance value of the energized coils is constant, and the sensitivity does not change depending on the position of the objective lens holding member 2.

In the above embodiment, a wire supporting structure using four wire springs 5 has been described as an example of a structure for supporting the objective lens holding member 2, but a known shaft sliding structure as another supporting structure. Alternatively, a hinge structure or the like can be adopted.

FIG. 7 is a plan view for explaining a schematic configuration of a seek device in an optical pickup device according to a third embodiment of the present invention, and FIG. 8 is a side view of FIG. 7, showing a basic configuration of the seek device. Is similar to the seek device shown in FIG.

In FIGS. 7 and 8, although not shown, the carriage 11 is mounted with, for example, the objective lens moving device and the objective lens 10 in the first and second embodiments. The installation structure of an optical system such as a laser and a collimating lens is a known structure, that is, a structure in which the optical system is directly installed on the carriage 11, or an optical system is installed on the base 7 and an objective is mounted by a mirror or the like. For example, a structure in which a means for guiding light to a lens is provided is employed.

The carriage 11 is guided by a seek rail 12 and moves smoothly in the radial direction of the optical disk D so that the light emitted from the objective lens 10 is condensed at an arbitrary position on the optical disk D. A magnet 16 magnetized in a direction perpendicular to the moving direction is fixed to the carriage 11, and a drive coil 15 wound around a yoke 14 in the moving direction of the carriage 11 is fixed to the driver base 13. The drive coil 15 is constituted by a plurality of element coils 15a to 15n provided side by side in the moving direction. These element coils 15a to 15n are connected in series, similarly to the configuration of the focusing coils 3a to 3e in the above-described embodiment. Wiring is performed from each connection point of the element coils 15a to 15n, and the element coils to be energized are connected. It is switched by a switch. The position of the carriage 11 is detected by detection means (not shown), and the carriage 11 is driven by energizing only the element coils close to the magnet 16 in accordance with the movement.

As shown in FIGS. 9A to 9D, the length Lc of each of the element coils 15a to 15n in the moving direction is shorter than the length Lm of the magnet 16 in the moving direction. The coils are selected from a plurality of element coils 15a to 15n so that the magnet 16 is always in the magnetic field generated by the coil in accordance with the movement of the coil, and the length of the energized coil is longer than the length of the magnet 16. The element coils at the ends of the drive coil 15 are sequentially switched in the moving direction while maintaining the state of energization. By doing so, the magnetic field affecting the magnet 16 is made substantially constant,
A smooth driving force can be generated.

Further, by setting the total resistance value of the element coils 15a to 15e which are always energized by the movement of the carriage 11, the sensitivity can be prevented from being changed.

[0039]

As described above, according to the objective lens driving device of the present invention, the movable range is switched by appropriately changing the element coil to be energized depending on the medium to be used, and the energization is performed only on the necessary portion. Thus, the linear density of the coil can be increased in a space equivalent to that of a conventional device of this type, and power consumption and heat generation during driving can be suppressed.

Further, according to the objective lens driving device of the present invention, the energization of the element coils is performed efficiently, and the driving force in the rotating direction caused by the movement of the objective lens holding member is reduced, so that the dynamic tilt is reduced. And the change in driving force (gain fluctuation) caused by the movement is also reduced.

Further, according to the seek device of the present invention, the linear density of the coil can be increased in the same space as that of a conventional device of this type, and power consumption and heat generation can be suppressed. Further, since the driving force in the rotation direction generated by the movement of the carriage is reduced, the dynamic tilt is reduced, and the change in the driving force (gain fluctuation) caused by the movement is also reduced. In addition, since the magnetic field generated by the current of the coil affecting the magnet becomes substantially constant, the carriage can be driven smoothly within the moving range.

Further, by making the total resistance value of the energized element coils always substantially constant, it is possible to eliminate the change in the sensitivity and to perform the driving smoothly.

Further, by arranging the respective element coils so as to be symmetrical with respect to a plane perpendicular to the moving direction at the time of the driving, the driving is performed smoothly as described above, and the coils are configured efficiently. be able to

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view of a schematic configuration of a main part of a moving magnet type objective lens driving device for describing a first embodiment of the present invention.

FIG. 2 is a wiring diagram of element coils according to the first embodiment.

FIG. 3 is an explanatory diagram of driving of an objective lens holding member according to the first embodiment.

FIG. 4 is a sectional view showing a schematic configuration of a main part of a moving magnet type objective lens driving device for explaining a second embodiment of the present invention;

FIG. 5 is a wiring diagram of element coils according to a second embodiment.

FIG. 6 is an explanatory diagram of driving of an objective lens holding member according to a second embodiment.

FIG. 7 is a plan view illustrating a schematic configuration of a seek device in an optical pickup device according to a third embodiment of the present invention.

FIG. 8 is a side view of a seek device according to a third embodiment.

FIG. 9 is an explanatory diagram of driving of a carriage in a third embodiment.

FIG. 10 is a partial cross-sectional view for explaining a schematic configuration of a main part in a conventional moving magnet type objective lens driving device.

FIG. 11 is a configuration diagram showing a planar state for explaining a seek mechanism in a conventional optical pickup device.

[Explanation of symbols]

 1, 10 Objective lens 2 Objective lens holding member 3 Focusing coil 3a to 3e, 15a to 15n Element coil 4 Tracking coil 5 Wire spring 7 Base 8, 16 Magnet 9, 14 Yoke 11 Carriage 12 Seek rail 13 Driver base 15 Drive coil

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5D068 AA02 BB01 CC08 EE05 GG03 GG05 5D117 JJ02 JJ05 5D118 AA13 BA01 BF02 BF03 CA11 CA13 DC03 EA03 ED08 5D119 AA10 AA24 AA37 BA01 DA01 DA05 JA43 JC04

Claims (6)

[Claims] 1. An object lens holding member holding an objective lens forming a light spot and having a magnet on a side portion, and a base member provided with a driving coil opposed to the magnet, In an objective lens driving device of an optical pickup device configured to drive the objective lens holding member together with the objective lens in a predetermined direction by energizing the driving coil, a supporting member that drives the driving coil parallel to the driving direction A plurality of element coils wound around the object are arranged in series, and a means is provided for energizing only at least one element coil existing within a movement range required for driving. Lens drive. 2. An object lens holding member holding an objective lens forming a light spot and having a magnet provided on a side thereof, and a base member provided with a driving coil opposed to the magnet, In the objective lens driving device of the optical pickup device configured to drive the objective lens holding member together with the objective lens in a predetermined direction by energizing the driving coil, the driving coil is wound around a support parallel to the driving direction. An optical pickup comprising: a plurality of turned element coils arranged in series; and means for energizing only at least one element coil close to the magnet during a moving process during driving. Objective lens drive in the device. 3. The objective lens driving device for an optical pickup device according to claim 1, wherein the driving coil is configured such that the total resistance value of the energized element coils is always substantially constant. 4. The objective lens in the optical pickup device according to claim 2, wherein in the driving coil, each element coil is arranged so as to be symmetrical with respect to a plane perpendicular to the moving direction at the time of driving. Drive. 5. A carriage on which an optical component for forming a light spot and an objective lens driving device are mounted, and a carriage on which a magnet is provided on a side, and a driving coil is installed so as to face the magnet. A seek device in an optical pickup device that includes a member and drives a carriage in a predetermined direction by energizing the drive coil, wherein a plurality of the drive coils are wound around a support parallel to the drive direction. In a seek device configured to arrange the respective element coils in series and to energize only the element coils close to the magnet during the movement process at the time of driving the carriage, in the moving direction of the respective element coils in the moving direction, A seek device in an optical pickup device, wherein the length is shorter than the length of the magnet in the moving direction. 6. The seek device in the optical pickup device according to claim 5, wherein the drive coil is configured such that the total resistance value of the energized element coils is always substantially constant.