JPH07122004A - Pickup supporting device - Google Patents

Abstract

PURPOSE:To enhance the track following performance by reducing an effect of sliding friction and making an optical pickup freely movable with smaller acceleration. CONSTITUTION:The optical pickup 1 is supported movably to an optical recording medium in the tracking direction by two guide shafts 6a and 6b, and the optical pickup 1 is driven along the guide shafts 6a and 6b by a driving coil 3. Then, the guide shaft 6b is inserted-into a main shaft bearing 4, which is formed as a separate body from the optical pickup 1, while the guide shaft 6a is engaged with a driven shaft bearing 2, which is formed integrally with the optical pickup 1, and the main shaft bearing 4 and the optical pickup 1 are combined by leaf springs 5a and 5b. These leaf springs 5a and 5b are disposed to cross their extended lines in the vicinity of a center of the driven shaft bearing 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pickup supporting device used in an optical disk device or the like.

[0002]

2. Description of the Related Art A pickup supporting device according to the prior art will be described in detail below. FIG. 5 shows the structure of a pickup supporting device used in a conventional optical disk device, and the structure will be described. This is disclosed in Japanese Patent Laid-Open No. 2-64971. In FIG. 5, reference numeral 11
Denotes an optical pickup, which is inserted through guide shafts 12a and 12b arranged in parallel in a main bearing 14 and a driven bearing 15, and is inserted in a radial direction of a disc (not shown), that is, arrow a, in the figure.
It is movably supported in the b direction. In this optical pickup 11, a linear motor 13 for transfer driving is arranged at one end portion orthogonal to the moving direction thereof.

In this linear motor 13, a permanent magnet 13b magnetized in the thickness direction is attached to a side portion of a yoke member 13a formed of a magnetic material in a frame shape to form a magnetic circuit. The yoke member 1 corresponding to the permanent magnet 13b
A drive coil 13d having a bobbin 13c wound around it is movably supported on the side of 3a in the directions of arrows a and b in the figure. In the optical pickup 11, when a current is supplied to the drive coil 13d of the linear motor 13, a propulsive force is generated in the drive coil 13d, and the drive coil 1d
The transfer is driven in the directions of arrows a and b together with 3d.

In such a conventional technique, sliding friction exists on the contact surface between the main bearing 14 and the driven bearing 15 and the guide shafts 12a and 12b. Therefore, the propulsive force F of the linear motor 13
Is small, the optical pickup 11 does not move, and the optical pickup 11 starts to move only when the propulsive force F becomes equal to or more than the static friction Fs.

Now, the coefficient of static friction of the contact surfaces of the main bearing 14, the driven bearing 15, and the guide shaft 12 is μ 0, and the mass of the portion including the optical pickup 11 and the drive coil 13d that moves in the directions of arrows a and b is M. , The supporting reaction force of the main bearing 14 is N1
, Where N2 is the reaction reaction force of the driven bearing 15 and g is the gravitational acceleration, the relationships expressed by the following equations (1) and (2) are established.

Fs = μ0 (N1 + N2) (1) N1 + N2 = Mg (2) Then, when the optical pickup 11 starts to slip and is in a moving state, a dynamic friction Fk smaller than the static friction Fs is opposite to the moving direction. Act on. If this coefficient of dynamic friction is μ, the relationship expressed by the following equation (3) is established. Fk = μ (N1 + N2) (3) Therefore, the equation of motion of the optical pickup 11 in the moving state is given by the following equation (4), where α is the acceleration. Fs−Fk = Mα (4) Then, by substituting the equations (1) to (3) into the equation (4), the relation of the following equation (5) is established. α = (μ 0 −μ) g (5) The optical pickup 11 cannot continue to move in one direction of the arrows a and b, and the moving direction must be reversed. At that time, the optical pickup 11
Is stationary, a propulsive force equal to or greater than the static friction Fs is always required for the optical pickup 11 to continue moving.

[0007]

As described above, the acceleration α shown in the equation (5) is calculated by the optical pickup 11
Is the minimum acceleration that can occur in Therefore, the optical pickup 11 cannot move at an acceleration smaller than the acceleration α shown in the equation (5). That is, for example, μ 0 =
Assuming that 0.5 and μ = 0.1, the acceleration α is α = (0.5−0.1) × 9.8 = 3.92 [m / s from the equation (5).
² ], so that the pickup 11 is 3.92 [m / s ² ]
It cannot be driven with the following acceleration.

Further, according to the ISO standard, the track eccentric acceleration of a 90 mm rewritable disc is specified to be 3 m / s ² or less when the disc rotation frequency is 30 Hz (1800 rpm). Therefore, the optical pickup 11 according to the related art cannot follow the disc eccentricity at all.

Further, in the above-mentioned prior art, since the objective lens actuator built in the optical pickup 11 must be driven to make the objective lens follow the track eccentricity, the load of the actuator is large and the actuator is large and high. It had to come at a cost.

When a so-called "preload" is applied to push the optical pickup 11 against the guide shaft 12 in order to eliminate the rattling of the gap between the main bearing 14 and the driven bearing 15 and the guide shaft 12, Since the supporting reaction forces N1 and N2 of the respective bearings are much larger than the values expressed by the above equation (2), the influence of friction is great.

The present invention has been made in view of the above problems, and an object thereof is to reduce the influence of sliding friction, to make an optical pickup movable at a smaller acceleration, and to improve track following performance. It is in.

[0012]

In order to achieve the above object, a pickup supporting device of the present invention comprises a pickup for recording or reproducing information on an optical recording medium, and the pickup for the optical recording medium. An optical information recording / reproducing apparatus comprising two guide shafts that are movably supported in a tracking direction and a drive unit that drives the pickup along the guide shafts, and one of the two guide shafts. The main bearing formed separately from the pickup, the driven bearing integrally formed with the pickup by engaging with the other of the two guide shafts, and the main bearing and the pickup are coupled to each other. A plurality of elastic members, and the plurality of elastic members are arranged such that extension lines thereof intersect near the center of the driven bearing.

[0013]

That is, in the pickup supporting device of the present invention, the optical pickup and the main bearing are separated from each other, and the optical pickup and the main bearing are connected by two plate-like elastic bodies having surfaces perpendicular to the disc. There is. The plate-shaped elastic body is arranged so that the extension lines of the plate-shaped elastic body intersect near the contact surface between the driven bearing and the guide shaft.

Further, when a propulsive force acts on the optical pickup, the plate-like elastic body is deformed, and the optical pickup rotates about the intersection line of the plate-like elastic bodies as a rotation axis. Since the driven bearing is close to the rotating shaft, it will slide only a very small amount.

At this time, since sliding friction occurs only in the driven bearing, the propulsive force at which the optical pickup starts to move, that is, the static friction Fs' is expressed by the following equation (6). Fs '= μ0 N2 (6) Then, when the optical pickup is in motion, the dynamic friction Fk' of the driven bearing and the reaction force f of the plate-like elastic body act in the direction opposite to the motion direction.

Now, the reaction force f of the plate-like elastic body is expressed by the following equation (7), where k is the spring constant of the plate-like elastic body and x is the amount of deformation of the plate-like elastic body. f = kx (7) Therefore, the equation of motion of the optical pickup is expressed by the following equation (8).
Indicated by. Fs′−Fk ′ = Mα ′ + f (8) Then, when this is rearranged, it is expressed by the following equation (9). ([Mu] 0- [mu]) N2-kx = M [alpha] '(9) Further, since the eccentricity of the track of the disk is very small, x is regarded as almost "0", and N2 = aMg (0
If ≦ a ≦ 1), α ′ = (μ0−μ) N2 / M = a (μ0−μ) g = aα (<α) (10), and a conventional example in which sliding friction occurs even in the main bearing The optical pickup can be driven with an acceleration α ′ that is smaller than the acceleration α. In particular, in the case of so-called "vertical installation" in which the disks are vertically arranged, the main bearing supports the total weight of the optical pickup, so that the supporting reaction force N2 of the driven bearing becomes almost "0". In this case, the minimum drive acceleration α ′ of the optical pickup is not affected by the sliding friction at all.
Also becomes "0".

Further, when the flexural deformation of the plate-like elastic body becomes large and the reaction force f thereof becomes larger than the static friction μ 0 N1 of the main bearing, the main bearing offsets the flexure of the sliding plate-like elastic body, so that the plate-like elastic body The deformation amount x of the elastic body does not become excessive, and the above relationship is always established.

For example, in the same way as the conventional example shown above, μ0
= 0.5, μ = 0.1, the supporting reaction force of the main bearing is N1 =
If N2 = 1 / 2Mg, that is, a = 0.5, α '= 0.5 × (0.5-0.1) × 9.8 = 1.96
[M / s ² ] and the optical pickup can move even at half the acceleration of the conventional one.

As described above, according to the present invention, the optical pickup can follow the large acceleration range of the track eccentricity acceleration of 3 m / s ² or less, so that the load on the actuator is reduced. Further, as described above, in the case of so-called "vertical installation", it is possible to follow the track eccentricity only by driving the optical pickup.

[0020]

Embodiments of the present invention will be described below with reference to the drawings. First, FIG. 1 shows a perspective view of a pickup supporting device according to a first embodiment of the present invention, and FIG. 2 shows a plan view thereof for explanation.

As shown in FIGS. 1 and 2, a driven bearing 2 having a U-shaped groove 2a is provided on one side surface of the optical pickup 1, and a drive coil 3 is fixed to the opposite side surface thereof. Has been done. And the two main bearings 4a, 4b
The main bearing member 4 having the above and the optical pickup 1 are connected by two leaf springs 5a and 5b.

Then, the driven bearing 2 and the main bearings 4a, 4
Two guide shafts 6a and 6b arranged in parallel are inserted in b. The surfaces of the guide shafts 6a and 6b are coated with tetrafluoroethylene resin. The width of the U-shaped groove 2a of the driven bearing 2 is slightly larger than the diameter of the guide shaft 6a. Further, the hole diameters of the main bearings 4a and 4b are formed to be slightly larger than the diameter of the guide shaft 6b, and the main bearings 4a and 4b can slide along the guide shaft 6b. The main bearing member 4 is in a state of floating inside the drive coil 3.

Further, a closed magnetic circuit 7 is formed by two yokes 7a and 7b having the same L-shape and a magnet 7c. One of the yokes 7a is in a state of floating inside the drive coil 3 and causes a magnetic flux to act on the drive coil 3.

The leaf springs 5a and 5b are perpendicular to a disk (not shown), and the optical pick-up 1 side is narrow and the main bearing member 4 side is wide so that the extension lines intersect at substantially the center of the driven bearing 2. Will be placed. A hole 5c through which the guide shaft 6b passes is also provided.

On the surface of the driven bearing 2 opposite to the optical pickup 1, a flexible printed board (FP
C) 8 is attached, and the FPC 8 is a guide shaft 6
It is drawn out along a and is formed to have a U shape, and the other end is fixed to a base (not shown). This FPC
A coil drive current and various control signals are supplied to the optical pickup 1 via 8, and an information signal from the optical pickup 1 is also guided.

Here, as shown in FIG. 3, the drive coil 3
When a current flows through, a propulsion force is generated according to Fleming's law, and the leaf springs 5a and 5b are deformed by the propulsion force.
Since the two leaf springs 5a and 5b are arranged so that their extension lines intersect at substantially the center of the driven bearing 2, the leaf springs 5a and 5b
Due to the deformation of 5b, the optical pickup 1 rotates around the driven bearing 2 as a rotation axis.

As a result, the objective lens 9 located away from the center of rotation moves in the disk radial direction (not shown). At this time, since the sliding amount of the driven bearing 2 is close to the rotation center, it is extremely small, and the energy lost due to the sliding friction is small. That is, the energy applied to the drive coil 3 is used to effectively move the optical pickup 1.

As described above, in the pickup supporting apparatus according to the first embodiment, no slip occurs in the two main bearings 4a and 4b, and only the sliding friction of the driven bearing 2 affects the optical performance. The pickup 1 is driven with a smaller acceleration. Further, since the optical pickup 1 and the drive coil 3 are arranged to be distributed to the main bearings 4a and 4b, most of the load of the moving portion is caused by the main bearings 4a and 4b.
The load acting on the driven bearing 2 is small. Therefore, the influence of sliding friction becomes smaller.

Next, FIG. 4 shows a plan view of a pickup supporting device according to the second embodiment, and will be described. As shown in FIG. 4, a drive coil 3 is fixed to one side surface of the optical pickup 1, and a driven bearing 2 is attached to the outside thereof. A main bearing member 4 is arranged so as to face the opposite side surface of the optical pickup 1, and is connected to the optical pickup 1 by two leaf springs 5a and 5b.

The two leaf springs 5a and 5b are
The extension lines are arranged so as to intersect at substantially the center of the driven bearing 2. Then, the driven bearing 2 and the main bearings 4a, 4a
Two parallel guide shafts 6a and 6b are inserted in b. The surfaces of the guide shafts 6a and 6b are coated with tetrafluoroethylene resin.

Further, although not shown, a magnetic flux of a magnetic circuit 7 in which a yoke and a magnet are arranged acts on the drive coil 3 in a direction perpendicular to the plane of the drawing. A projection 1a extends from the side surface of the optical pickup 1 on the main bearing member 4 side. The two wall portions 4c and 4d near the center of the main bearing member 4
Two silicon gel dampers 10 are sandwiched between and the protrusion 1a. Therefore, the optical pickup 1
Is absorbed by the damper 10 and the control of the optical pickup 1 is stabilized.

As described above, in the pickup support device according to the second embodiment, the main bearing member 4 and the driven bearing 2 are provided.
Since the distance between and becomes large, the crossing angle of the two leaf springs 5a and 5b can be made small, and the width of the main bearing member 4 can be made small. Therefore, the pickup supporting device can be downsized.

As described in detail above, in the pickup supporting device of the present invention, the influence of the sliding friction of the main bearing is reduced,
Since the friction loss in the driven bearing is also minimized, the optical pickup can move up to a small acceleration and the track following performance can be improved.

[0034]

According to the present invention, it is possible to provide a pickup supporting device in which the influence of sliding friction is reduced, the optical pickup is movable with a smaller acceleration, and the track following performance is improved.

[Brief description of drawings]

FIG. 1 is a perspective view of a pickup support device according to a first embodiment of the present invention.

FIG. 2 is a plan view of the pickup support device according to the first embodiment.

FIG. 3 is a diagram showing a state in which a pickup is displaced by a driving force of a driving coil 3 in the first embodiment.

FIG. 4 is a plan view of a pickup support device according to a second embodiment of the present invention.

FIG. 5 is a diagram showing a configuration of a pickup support device used in a conventional optical disc device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Optical pickup, 2 ... Driven bearing, 2a ... U-shaped groove, 3 ... Drive coil, 4 ... Main bearing member, 4a, 4b ... Main bearing, 5a, 5b ... Leaf spring, 6a, 6b ... Guide shaft, 7 …
Closed magnetic circuit, 7a, 7b ... Yoke, 7c ... Magnet, 8 ... Flexible printed board, 9 ... Objective lens, 10 ... Damper.

Claims (1)

[Claims] 1. A pickup for recording or reproducing information on an optical recording medium, two guide shafts for movably supporting the pickup in the tracking direction with respect to the optical recording medium, and the guide for guiding the pickup. An optical information recording / reproducing apparatus having a driving means for driving along an axis, comprising: a main bearing which is inserted through one of the two guide shafts and is formed separately from the pickup; and the two guides. A driven bearing that is engaged with the other of the shafts and that is integrally formed with the pickup; and a plurality of elastic members that connect the main bearing and the pickup. A pickup support device, which is arranged so as to intersect near the center of a driven bearing.