JPS5990240A - Objective driving device - Google Patents

Abstract

PURPOSE:To obtain an objective driving device with a simple structure which is assembled easily by supporting the objective movably in an optical-path direction and the direction orthogonal to the optical axis and providing a coil which displaces the objective in both directions. CONSTITUTION:The objective 21 is applied with force in a focus direction A by a focusing coil 26 and a magnetic field generating means 27; and the objective 21, lens frame 22, and the focusing coil 26 slides in a sliding frame 23 in the focus direction A in one body. On the other hand, the objective 21, lens frame 22, and focusing coil 26 receive force in a radial direction B through the operation of a radial coil 33 and a magnetic field generating means 34 to be displaced through the fine gap between the sliding frame 23 and lens frame 22 while receiving the repulsion of parallel springs 24-1 and 24-2. Thus, the objective driving device of a simple structure which is assembled easily is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a digital A-dio disc (DAD),
Objective lens drive device suitable for use when recording/producing 'l# information on optical discs such as video discs (VD) or magneto-optical discs that utilize the Kerr effect or 7 Alladay effect. This is the first time for 1' time.

In 'JAii\, which records and reproduces fi'/information on optical discs and magneto-optical discs, recording or (l
+414 relative position between the objective lens and the disk to project the Ikukawa mechahim as a spot onto the disk'+
R.

In order to correct the deviation, that is, the force-shinging difference, and to prevent the relative positional deviation between the light spot projected on the disk and the disk, and the dragging error, the objective lens is The optical axis direction and the direction that intersects the optical axis with IIT (usually the radial direction of the disk)
It is necessary to displace it in two directions.

Various such AI object lens driving devices 1q have been proposed in the past, and this one is also proposed, for example, in JP-A-56-9.
No. 4311, No. 71, No. 4,) has already proposed a structure not shown in the gaps A and B. This burn-out lens III device i' (is a device that holds an objective lens 1 in a holding frame 2 made of a magnetic material, and holds this holding frame 2 between a pair of parallel leaf springs 8-1 and 3-2 to an intermediate frame. 4, the objective lens 1 is supported so as to be movable in the direction orthogonal to the optical axis indicated by the arrow, that is, in the radial direction, and the middle frame 4 is supported via a pair of thinly wound springs 5-1 and 5-2. and place it on the outer frame 6 (
The middle frame 4, and therefore the 71-piece lens 1, is displaced in the optical axis direction, that is, in the focus direction. In order to displace the objective lens l in the radial direction, a magnetic field generating means having a permanent magnet 7-1, 7-2 and a yoke 8-1°8-2 is attached to the outer frame 6 so as to surround the holding frame 2. coils 9-1., 9-2 for supplying tracking loops (coils 9-1, 9-2 for supplying a difference signal) and cooperating with the magnetic field generating means.
However, the yoke 8-1 facing the holding frame 2. , 8-2. In addition, in order to displace the objective lens 1 in the focus direction, a coil 11 for supplying a force-twisting error signal is wound around a ring 10 provided integrally with the middle frame 4, and the coil 11 works together with the ring 10. A magnetic field generating means consisting of a permanent magnet 12 and yokes 13 and 14 is attached to the outer frame 6. In addition, holding frame 2 and coil ≦1
-1 and 9-2, for example, Ferrofluid (
J”errofluidics) exclusive magnetic fluid 15
is filled.

In the objective lens driving device not shown in FIGS. 1A and 1B, the objective lens is driven by a parallel leaf spring 3-1.8-2 and a pair of spiral springs 5-1. Since the objective lens 1 is supported with a displacement 11 in the radial direction and focus direction, the objective lens 1 is stable and (rI
II can indeed be supported.

However, when supporting the objective lens l via a spring, it is necessary to suppress the Q of the natural resonance and prevent resonance at high frequencies.
In order to achieve this, it is necessary to use a viscoelastic material made of rubber thread, such as silicone rubber, butyl rubber, or a mixture of both, in combination with a spring made of an elastic metal material, which makes assembly and adjustment complicated. There is. Furthermore, when an LM movement is applied in the focus direction while the objective lens 1 is displaced in the radial direction as shown in FIG. 2A, the parallel leaf spring 8-1
At ゜8-2, the vibration mode shown in Figure 2B is 2.4K.
There is also a problem that occurs near IIZ and causes the focus vibration system to become unstable.

The first object of the present invention is to eliminate the two consecutive problems, to stably displace the objective lens in the direction of its optical axis and in the direction orthogonal to the optical axis, and to make it easy to assemble the 1Q structure. The objective is to provide an objective lens drive device that is appropriately controlled.

The present invention provides an objective lens driving device for displacing an objective lens in a direction perpendicular to the light 11q+1 direction and the optical axis, which includes: a supporting means for elastically supporting the holding means with a displacement force in a direction perpendicular to the optical axis of the objective lens; a first magnetic field generating means for displacing the objective lens in the direction of its front axis; The first step to working together
, a second magnetic field generating means for displacing the diJ objective lens in a direction perpendicular to the optical axis, and a second coil cooperating with the second magnetic field generating means. be.

The present invention will be described in detail below with reference to the drawings.

FIG. 8 is an exploded perspective view showing the structure of an example of the objective lens driving device of the present invention. The objective lens 21 is held in a lens frame 22, and this lens frame 22 is held in a sliding position 23 in the direction of the optical axis of the proboscis lens 21, i.e., in the focus direction.

The lens frame 22 is made of aluminum to reduce the weight of the lens frame 11ε.
\°! 14 material, and a sliding frame 2 is attached to the outer circumference.
In order to move smoothly and without wear on the inner peripheral surface of 3, apply a coat of hard material 'P7 to the sliding frame 23 along with blood stains.
A smooth deflon-based material 'eI is attached to the inner circumferential surface of the
Iazu.

The sliding frame 28 has two parallel leaf springs 24-1 and 24-
Fixed via 2 + tl (4 m' Taken at 25 (=J), this allows the sliding + 1jlJ frame 23, and therefore the objective lens 2
1 is supported by a displacement + iJ in a direction perpendicular to its optical axis, that is, in a radial direction, as indicated by a double arrow B.

On the other hand, in order to displace the objective lens 2 in the focus direction A by sliding the lens frame 22 against the sliding frame 23,
A focus filter 26 is integrally wound around the lens frame 22 in the focus direction A for supplying a force focusing error number [f], and together with this focus filter 26, a focus filter 26 is wound. The magnetic generating means 27 of the force is connected to the fixed part A'A25 via a connecting means (not shown).
Take f=J number. The magnetic field generating means 27 is 1 lJ as shown in FIG.
As shown in the figure, a ring-shaped permanent magnet 28, a ring-shaped yoke 29 fixed to one end m1-1- of this permanent magnet 28, and a ring-shaped yoke 29 fixed to the other end surface of the permanent magnet 28, the yoke 29 and facing each other with a gap 30 in between, and recording or 1
A yoke 32 is provided with an rt through hole 31 through which the optical beam for 1j production passes. This magnetic field generating means 27 is arranged between IH (
Hs.

The focus coil 26 is placed at position i4, that is, the 7th sub-cass coil 26 is exposed to the magnetic flux passing through the center. ! do. Note that the gap 3() is wide enough to prevent the focus coil 26 from coming into contact with the yokes 2D and 32, respectively, when the objective lens 21 is disposed in the radial direction B.

Also, in order to displace the moving frame 23, and therefore the objective lens 21, in the radial direction B, j; A magnetic field generator 49 for tracking is wound with a radial coil 33 for supplying a difference signal and works in cooperation with this radial coil 83:
Fixed r'ilf 4'/l 25 via means (=
J-Kell. This (L!lW U'd raw Senju 123 + magnetic field generating means 27 for force tsusing: 15 and 1゛ = 1 Same except that there is no through hole 81) n (1゛11 Hiroshi, permanent The radial coil 33 is arranged so that the position 11·t is between the two yokes through which the magnetic flux of the magnet passes.
The interval at which the radial coil 33 of the magnetic field generating means 34 is inserted is wide enough so that the radial coil 3.3 does not come into contact with the yoke when the objective lens 2J is displaced in the focus direction A.

In the objective lens driving device shown in FIG. The control coil 22 and the focus coil 26 are integrally displaced,
Also, in the radial direction B, radial coils 83J5 and 4
The i'l moving frame 23 connects the objective lens 21, lens frame 22 and frame coil 26 with the parallel leaf spring 24-1.
And 24-2 is displaced while receiving a repulsive force returning to the neutral point. That is, l<f The object lens 21 is displaced in the focus direction A by directly receiving the force in the focus direction due to the action of the focus coil 26 and the magnetic field generation means 27, and in the radial direction B by the force of the radial coil 33 and the magnetic field generation means. The force in the radial direction due to the action of 3Φ is
It is indirectly received and displaced through the gap between the sliding frame 23 and the lens frame 22 with bare hands.

FIG. 5 shows an objective lens 11 of the present invention. ! ! ilJ1;
3, which is an exploded perspective view showing the (1-I configuration) of the example of the pond of ゛t.
In this example, the magnetic field generating means for displacing the objective lens 21 in the A-cus direction and the radial direction is shared, and this magnetic field generating means and the force force
The objective lens 21 receives forces acting in cooperation with the focus coil to which the difference signal is supplied and the radial coil to which the tracking error signal is supplied.
The lens 21 is held in a lens frame 22, and a rectangular coil frame 85 is attached to this lens frame 22. In the frame 35, as stated in 'Office Opening and Closing No. 54-94007 flJ,
On its outer circumference, there is a focus coil 26 for supplying a sub-cut lens error signal (as well as a radial coil 33 for supplying a tracking difference signal to each of the four corners) A-cast filter 26-
Glue the edges to the top and wrap. .

On the other hand, the m '714 generating means 36 is equipped with a base 37 made of a magnetic material, and a permanent Ishii 1 of a magnet (1411 so that the weight is in the S and J names) is placed opposite to the base 37 for 1411 seconds. '38-1.

38-2 (J), and a yoke 89-1°39-2 in contact with the same magnetic pole face of one of these magnets, in this example, the S pole face.
Establish ζ). Also, forever? B stone 88-1.

;l 8-2 (1R other Jj's identity (1R Gokuji and between 11
e+ 40-1.

1.Yoke 4 to base 87 via ()-2], -
], .

1.1-2 is installed J1 permanent IIu stone 38-1 generates a 1μ east is transmitted to yoke 3D-1 via gap 40-1, yoke 4.1-1 and base 7, and is attached to permanent magnet a. The magnetic flux generated from s -2 is between 11i140-
2. Yoke 31 via yoke Φ1-2 and base 37
)-2, that is, the permanent magnet 38-1°3
The hole east caused by 8-2 is gap 40- ], , 4
(Make sure that 1-2 passes in the λ・1 symmetric direction.

In addition, the yoke 41-1 and the yoke 41-2 hold the sliding frame 23, which holds the lens frame 22 so that it can slide in the direction A, in parallel. Yoke + through two mutually telling plates 2+-i, 2+-2
1-1, 41. -2 displacement in radial direction B 111
The coil frame 35 is attached to the sliding frame 2; 3 with the gap 4.
0-1, 40-2, and these gaps 40-1.
The lens frame 22 is placed so that the magnetic flux passing through the lens frame 22 is exposed to the magnetic flux passing through the lens frame 40-2.
fIIInf function. According to C1-sei,
Since the coil frame 35 in which the focus coil 26 and the radial fill 33 are wound is attached to the lens frame 22, the objective lens 21 can absorb the force acting in the focus direction A and the radial direction B through the cooperation of these coils and the magnetic field generating means 36. 1a reception, 7A - lens frame 22 in the scrap direction A
moves smoothly 1i9i with respect to the sliding frame 23, and the objective lens 21, lens frame 22, coil frame 35, focus coil 26 and radial coil 33 are integrally displaced. , lens frame 22, coil frame;
1, 24. -2 will be displaced while receiving the repulsive force that approaches the neutral point. l In this example, when the objective lens 21 is positioned in the radial direction, the lens frame 22 and the coil frame 35 rotate,
The fill frame 35, the focus coil 2 fi:l-; and the radial coil 33 are permanent magnets 38-1 and 38-2.
) Ie rr'Z on the base 37 to prevent it from coming into contact with the yokes 41-1, 41-2.

The moving beam passes through the lens frame 22 and passes through the objective lens 21.
Loosely fit the lens frame 22 into the through hole 1112.
At the same time, there is a hole at the bottom end of the lens frame 22.
- Two notches 43 extending in the scrap direction A are formed, and these notches are passed through the base 37 and inserted into the through hole 42 in the radial direction B. Engagement 11, Fig. 6i;
In this example, in the objective lens driving device shown in FIG. 7
It is attached to a 11flJ frame 23, and with respect to the optical system G, only the objective lens 21 can be displaced in the focus direction, and the entire optical system including the objective lens 21 can be displaced in the radial direction. The optical system of the objective lens 21) is as follows:
In this example, a laser diode 45, a collimator lens 46
, beam splitter 47, criticality 1ijfu+) Snow＼
4.8 and 4-division 7 Otodai A-do 4g sliding frame 23
The optical beano for recording or reproducing which outputs q= from the laser diode II5 is attached to the collimator lens 4.
6, the beam splitter 47 passes through the printing lens 21, and the reflected light is projected onto the disk (not shown) -1- in the form of a spot, and the reflected light passes through the printing lens 21 and the beam splitter 47, where it is reflected at a critical angle. The reflected light from the optical sections 4 and 8a, which are made incident on the prism 48 and set so that the light in the direction of the tip axis strikes at almost the critical angle, is July - Force Soleng l'+'J
? I (divided into 4 for convenience of tracking information) A to diode 4;ノ 4 sa 7ru.

(According to J'l construction, only the objective lens 2J is displaced in the focus direction with respect to the optical system, so this 14
1rt11t h of the 5th working i da IX becomes lighter, and since the entire optical system including the kJ object lens 2 is in the bag position in the radial direction, even if its displacement nt is large, their optical position 1i' 1 will not shift. Therefore, it is possible to always accurately record and reproduce the '11'7 report.

It should be noted that the present invention is not limited only to the above-mentioned example, and many other forms or variations are possible.

For example, t:j', In Figure 3, the leaf spring 24-1. ．． Placed differently?
The sliding frame 23 may be supported by the sliding frame 23, or conversely, in FIG. 5, the plate springs 2+-J and 24-2 are arranged on one side as shown in FIG. j The IS moving frame 23 may be supported by the yokes 41-1 or 41-2. In addition, as shown in FIGS. 7A and 7B, rigid plates 50-1 and 50-2, such as carbon fiber, which are light and do not bend, are attached to a viscoelastic body 51 of rubber thread as a substitute for a leaf spring. Through the sliding frame 23 and fixed '! J
52, it is also possible to elastically support the movable frame 23 by displacing it in the radial direction.In this case, the Q
can be reduced. Furthermore, as shown in FIG. 8, the sliding frame 28 is fixed to one end of the arm 53, and the pond end of the arm 53 is pivoted around the shaft 54 to the identification end 52. 11 of the arm 53 [σ side edge and fixed end 5
Spring 55-1.2 extends in the radial direction between spring 55-1. ,
55-2 can also be installed to elastically support the sliding frame 23 with the ability to displace u1 in the radial direction. 1 Furthermore,
In the 31st fi, the optical system other than the objective lens 21 can also be mounted on the sliding frame 23 as in FIG. 6.

In addition, in FIGS. 8 and 5, λ・J objects 21
It is also possible to configure the entire optical system including the lens frame 22 to be attached to the lens frame 22 so as to be integrally displaced in the focus direction and the radial direction. Further, in the above example, the objective lens 21
The driving means for displacing in the focus direction and the radial I direction is an iJ moving coil type in which a filter that cooperates with the magnetic field generating means is displaced.
An iJ dynamic magnet type may also be used.

As mentioned above, in the present invention, the support 411I structure for moving the objective lens in the focus direction is not used and the 411I structure is used for sliding the objective lens, so that the displacement in the radial direction is It is possible to obtain a stable A-cass vibration system without being affected by the vibration, and the resonance in the high range peculiar to the spring structure is less likely to occur, and the sarpo gain can be increased. Therefore, it is particularly effective when there are 4 or 5 disks arranged in 11 trees, such as video disks. In addition, as for the support 11-I structure in the radial direction, since the objective lens is made of a spring (]゛I structure that has a repulsion force of 4'J at all times, the videota disk If the carriage lever is moved simultaneously in the radial direction along with the objective lens drive unit) in the 15-direction direction,
The yaw operation can be performed reliably and stably. Therefore, i
It is possible to stably move a 4-object lens from position t. In addition, since the objective lens is supported by a sliding structure in the focus direction and a spring structure in the radial direction, assembly and adjustment can be easily performed using RFI! 5th to h'r
The assembly shown in the figure can be assembled from one direction. Furthermore,
In FIG. 5, the force that displaces the objective lens in the radial direction is also applied to the objective lens by 1α, so the natural frequency is f. The effect is large in the higher frequency region, that is, in the mass region where the sensitivity is determined only by the quality 11 ahead.

[Brief explanation of drawings]

1st LJ A and B are conventional objective lens drive devices 2
Figures 2 and 3 are diagrams for explaining the inconvenience, and Figure 3 is a diagram showing (1) an example of the objective lens driving device 11 of the present invention.
Figure 4 shows the component Pl showing the component η (see Figure 5).
The figure is an exploded perspective view showing the configuration of another example of the objective lens driving device of the present invention, FIG. 6 is a miniature diagram showing the 4'l'17 configuration of the main part of still another example, and FIGS. 7A and B and Figure 8 shows sliding the objective lens +iJ'
Noh (Support of sliding frame with child (M +'?' Other 3 of 7)
FIG. 2 is a diagram showing two examples. 21... Objective lens, 22... Lens frame, 23...
・j111 moving frame, 24-1.24-2...plate spring, 2
5... Fixed member, 26... Focus fill, 27
．． 34...1 stage of magnetic field generation f, 28...1 permanent stone,
29.32... Yoke, 30... Interval E, 31...
vi communication hole 33... radial coil, 35... coil frame, 36... magnetic field generating means, 37... base, 3
8-J, 38-2...Permanent magnet, 3! 1-
1, 89-2, 41-1, ! 1-2...
・Yoke, 4.0-1, 4.0-2...lf+I
li, 42...Through hole, 4.3...J notch, 4
4... Rotation prevention body, 45... Laser diode, 4
6...Collimator lens, 47...Beam splitter, 418...Critical angle prism, 411...4, split fumetodiode, 5 fl-1, 50-2...
1 Rigid plate, 5i,, Viscous 1 Motile body, 52"'I',"
l % WILD % 5 +3'' Arm, 54・
...shaft, 55-1.55-2...spring. Figure 1 = 2 - Figure 2 Figure 8 Figure 4 Figure 5 Figure 6 (9) Figure 8

Claims (1)

[Scope of Claims] 1. A lens 111 that moves the objective lens in the direction perpendicular to the light 11qI+ direction and the optical axis (1-5 in the moving device 11) In the optical axis direction, there is a 1ν holding means for holding 1i'7 moving rivers 1) 1g and 1g, and this 1v holding means, ? 1) support means for elastically supporting the means in a direction G perpendicular to the optical axis of the objective lens described in No. 11; The J-th magnetic field generating means and the first coil coil working together with the J-th magnetic field generating means, and the +jiJ objective lens are
111, and a second magnetic field generator 12B that extends in a direction perpendicular to 111, and a second coil that cooperates with the stiffness. ? r: 'Objective lens driving device f'' for 'Q',
? '. 21JIJ d1! :Including, 1 coil to the above-mentioned S1 object lens and -1 f, 1 digit, 1] II, 2nd: J coil 1) 11, Ily to the holding means, iJ mouth to 11
+J-characteristic rt'l'tfl'J φI is also the first J'l'J +iL! 8. The first coil and the second coil are integrated with the objective lens, and the first magnetic field generating means and The second magnetic field generator J is formed by a common magnetic field generating means (1), and the objective lens drive device of item 11 & 11 & 4. Take an optical system other than the objective lens integrally with the means: At the J-th point, displace only the objective lens described in No. 111 in the direction of the optical axis, and displace the objective lens described in No. 111 and the other lenses in a direction perpendicular thereto. Patent i?i'J's lii' characterized in that the optical system is configured to be displaced.
(j) The objective lens driving device (i) described in Section 1 of the subsection (j).