JPS6185639A - Optical head device - Google Patents

Abstract

PURPOSE:To eliminate abnormal oscillation to make high-precision stable control possible by supporting an optical head with two parallel focus flat springs and supporting these flat springs with cross-shaped flat springs orthogonal to each other. CONSTITUTION:A focus spring 3 consisting of two flat springs is stuck to a coil unit 2 to which an object lens 1 is attached, and the other end of the spring 3 is stuck to a repeating member 4. Two cross-shaped tracking springs 5 orthogonal to each other are stuck to the repeating member 4, and the other end is attached to a fixed supporting body 6. When power is supplied to a focus coil 8 in this constitution, the spring 3 is moved in the direction of an arrow F; and when power is supplied to a coil 9, it is moved in the direction of an arrow T. Thus, the resonance frequency causing abnormal oscillation is shifted to the high band to prevent abnormal oscillation, and the repulsion of the inertial force is reduced to perform the high-precision stable control.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention particularly relates to an optical head device η for recording and reproducing information on an optical recording medium.

[Technical background of the invention and its problems] With the recent improvement in digital signal processing technology, various digital recording methods have been developed. Efforts are being made to reduce information noise and distortion, and to increase the density of recorded information. Among them, for example, a disk coated with a gold FfA thin film is used, and various information is recorded by forming holes (bits) corresponding to digitized data on this disk.
Furthermore, devices that reproduce recorded information by detecting the presence or absence of this bit are being put into practical use.

By the way, such a disc (hereinafter referred to as "optical disc")
With the increasing density of recorded information, the bits formed in the bits have a diameter of approximately 1.0 μm or less and are formed with a track pitch interval of 1.0 to 2.0 μm. . For this reason, light is used to form bits to record information on an optical disc, or to detect the presence or absence of bits formed to reproduce information.
The optical head for this purpose has excellent tracking control and focus functions for optical discs, and is capable of highly accurate positioning of the light spot formed by the optical head for recording and reproducing information. It is required to have the following.

To meet such demands, the following optical head devices have been considered. FIGS. 7 and 8 show the structure and planar configuration of the relay member 16, in which a relay member 16 is supported on a cylindrical fixing member 15 via a focusing diaphragm spring 17. It has a structure in which a movable member 19 to which an objective lens 18, which is the main body of the optical head, is attached is supported via a parallel plate spring 20 for tracking, and the movable member 19 is moved for focusing and tracking in the directions of arrows A and B. It has become.

9 and 10, the relay member 22 is supported with respect to the fixing member 21 by a parallel leaf spring 23 for focusing, and The optical head body is a pair of 117 lenses and 24
The movable member 25 to which the movable member 25 is attached is supported by a parallel plate spring 26 for tracking.

By the way, in the optical head device having such a structure in which the movable member 19.25 is two-dimensionally movably supported,
It is necessary to be able to stably perform tracking control and focus control even in response to external shocks. For this purpose, it is usually necessary to increase the servo band to 2 kHz or higher. Therefore, in order to secure the servo band at about 2 kHz, it is necessary to adjust the characteristics of the suspension in the device having the structure shown in FIGS. In the operation characteristics determined by It is also necessary to suppress the vibration amplitude of resonance.

However, in the case shown in FIG. 7, since a driving force is applied to the relay member 16 to drive the objective lens 18 in the focus direction via the parallel plate spring 20, the objective lens 18 is driven in the focus direction. In the case, the parallel plate spring 2
The resonance frequency of the vibration system configured between the lens 0 and the objective lens 18, that is, the secondary resonance frequency, was low, and a sufficient servo band could not be obtained.

Furthermore, in the case shown in FIG. 8, since the driving force in the focus direction and the tracking direction is directly applied to the movable member 25, the secondary resonance shown in FIG. 9 is not affected. Parallel plate spring 2 that silently moves in the focus direction
Due to the influence of the mass of the relay member 22 that connects the parallel plate spring 26 displaced in the tracking direction, an abnormal resonance point as shown in FIG. 10 appears around 1 to 2 kHz,
The movable body resonates at the resonant frequency in response to a slight disturbance,
This made the control system unstable. Furthermore, when the movable member 25 is moved and displaced under focus control, the reaction force of the inertia horns that the relay member receives acts on the movable member 25, and this reaction force induces abnormal vibrations.

EObject of the Invention 1 The present invention has been made in consideration of the above circumstances, and its object is to have an objective lens support structure that does not generate abnormal vibrations, and to provide 1! The object of the present invention is to provide an optical head device that has good dynamic characteristics and is capable of highly accurate tracking control 11J5 and focusing υJt[I.

[Summary of the Invention] In order to achieve the above object, the present invention includes an optical head main body, a holder that integrally fixes the optical head, a relay member, a fixing member fixed to a base, and the A first elastic body that connects the holder and the relay member, and a second elastic body that connects the relay member and the fixing member, and the first elastic body is connected to the optical head main body. The optical system is elastically deformed in the optical axis direction, and one end of the second elastic body on the relay member side is elastically deformed with rotation around an axis parallel to the optical axis with respect to the one end on the fixed member side. This is an optical head device in which a head main body is movable in the optical axis direction of the optical head and in the R direction perpendicular to the optical axis.

[Embodiments of the Invention] The present invention will be described in detail below with reference to the drawings. 1st
The figure is a perspective view showing the present invention, and FIG. 2 is a bottom view thereof.

An objective lens 1 for converging a light spot on the disk surface is fixed to a coil unit 2 made of a rigid body. In order to move the whole of these parallelly in the focus direction F, which is the optical axis direction, without any twisting movement, one end of the focus spring 3 is made up of two parallel plate springs made of metal or other elastic members arranged perpendicular to the optical axis. is fixed to the coil unit 2, and the other end is fixed to the relay member 4. The above is the support structure in the focus direction.

On the other hand, one end of a tracking spring 5 consisting of two sets of cross springs orthogonal to each other is fixed to the relay member 4 so as to form a plane perpendicular to the focus spring 3. The other ends of these tracking springs 5 are fixed to a fixed support 6. The above is the support structure in the tracking direction. In this way, the focus spring 3 made up of a pair of parallel leaf springs deforms while maintaining a parallelogram relationship, and the tracking spring 5 made up of a pair of cross springs becomes
Since the objective lens 1 is rotationally deformed around the optical axis, the optical axis of the objective lens 1 itself is perpendicular to the disk in any direction of movement.

The coil unit 2 consists of a frame-shaped movable body 7, a focus coil 8, and a tracking coil 9. A planar tracking coil 9 wound perpendicularly to the optical axis direction of the tracking coil 9 and having a substantially rectangular shape is connected to the objective lens 1 of the tracking coil 9.
The movable body 2 is fixed so that the sides parallel to the optical axis are arranged at both ends of the sides parallel to the tracking direction T of the movable body 2.

The coil drive system 10 includes la pole members 11 and 12 made of a material that allows magnetic force to pass through, such as iron, and this! It has a permanent magnet 13 that magnetizes the IIf1 member. Magnetic pole member 11.1
2 holds both ends of the long side of the coil unit 2,
It has magnetic poles 11a and 12a arranged parallel to this side portion and spaced apart from the coil unit 2 by an appropriate length.

Next, the operation of the optical head device configured as described above will be explained. Focus coil 8 of coil unit 2
extend parallel to the upper and lower edges of the movable body 7 so as to be recessed on the side surface of the frame portion of the movable body 1 . In other words,
The conducting wire to this focusing coil 8 is perpendicular to the focusing direction. On the other hand, the magnetic poles 11a and 12a are
A magnetic field is applied between them. This magnetic field crosses the conducting wire of the focus coil 8 so as to be orthogonal to the focus direction F and the tracking direction Tk. Therefore, when the focus coil 8 is energized, a force moves in the focus coil 8 and, by extension, the coil unit 2 in a direction perpendicular to the current and the magnetic field, that is, in the focus direction F, according to Fleming's law. The magnitude and direction of this force are determined by the magnitude and direction of the current flowing through the focus coil 8.

In response to this force, the focus spring 3
While keeping the coil unit 2 and relay member 4 parallel,
The coil unit 2 and thus the objective lens 1 are deformed and moved in parallel in the focus direction F.

On the other hand, between the magnetic poles 11a and 12a, there is a portion of the tracking coil 9 located at both ends of the long side of the coil unit 2 and sandwiched between the magnetic poles Ha and 12a.

When this tracking coil 9 is energized, l1ti pole 1
Focus direction F of the part sandwiched between 1a and 12a
According to Fleming's law, a force moves in the direction in which the current flows and in the direction perpendicular to the magnetic field, that is, in the tracking direction T, in the rectangular side portion 9a that extends. Therefore, by passing a current through the tracking coil 9, the tracking coil 9, and thus the coil unit 2, receive a force in the tracking direction T, and the direction and magnitude of the force depend on the direction and magnitude of the current flowing through the coil. Determined. Due to this force, the tracking spring 5 is elastically deformed and the relay member 4 is rotated zero relative to the fixed support 6, as shown in FIG. 4 (states before deformation (a) and after deformation (b)). As a result, the coil unit 2 and the objective lens 1 move in the tracking direction T.

In the apparatus configured in this manner, the movement of the objective lens 1 in the tracking direction T is achieved by magnifying the rotational deformation of the tracking spring 9 by the focus spring 3 C4r7. Therefore, since the relay member 4 is distributed at a position closer to the center of rotation of the tracking spring 5, the equivalent quality of the relay member 4 is equal to the equivalent quality of the coil unit 2. (Equivalent fdli mass is proportional to the square of half IY from the center of rotation. Therefore, the abnormal resonance resonance frequency that conventionally appeared at 1 to 2 kHz can be suppressed by tracking J5 and force It can be shifted to high 1 stroke without affecting the servo.

In addition, since the equivalent quality degradation of the relay member 4 is reduced, the coil unit 2 is moved in the focusing direction E or in the tracking direction T.
When the coil unit 2 is moved and displaced, the reaction force of the inertial force of the relay member 4 that the coil unit 2 receives is small, and the abnormal vibration amplitude becomes sufficiently small. In this way, it is possible to reduce the force exerted on the movable body by the relay member that causes imaging, and to shift the resonant frequency of abnormal resonance to a high frequency range that does not affect the control system, resulting in stable control. Realizing this system will have great practical effects.

[Other Embodiment 1 of the Invention The present invention is not limited to the first embodiment. For example, as shown in FIG.
One leaf spring 14 parallel to the focus direction F and perpendicular to the focus spring 3 is attached to the elastic support member to be rotationally displaced relative to the focus direction F.
may also be used.

[Brief explanation of the drawing]

Fig. 1 is a partially cutaway perspective view showing the principle of an embodiment of the present invention, Fig. 2 is a plan view thereof, Fig. 3 is a side view showing the operating principle, and Fig. 4 is a plan view showing the operating principle. Fig. 5 is a partially cutaway perspective view showing the second embodiment, Fig. 6 is a plan view of Fig. 5, Fig. 7 is a sectional view showing the conventional example, and Fig. 8 is a plan view of Fig. 7. 9 are sectional views showing other conventional examples, FIG. 10 is a perspective view, and FIGS. 11 and 12 are 16-line diagrams illustrating resonance that often appears in optical head devices. 1... Objective lens, 2... Coil unit, 3...
- Focus spring, 4... Relay member, 5... Tracking spring, 6... Fixed support body, 7... Movable body, 8
... Focus coil, 9... Tracking coil, 9... Coil drive system, 11... Magnetic pole member, 12.
...Magnetic pole member, 13...permanent...stone. Agent Patent attorney Noriyuki Chika (Haka name) Fig. 2 δ II (1/10 ll: ll: ff (L Fig. 3 Fig. 4 Fig. 6 Fig. 7 Fig. 8 Fig. β Fig. 9 Figure 10 Figure 11

Claims (1)

[Claims] an optical head main body, a holder that integrally fixes the optical head, a relay member, a fixing member that is fixed to a base, a first elastic body that engages the holder and the relay member; a second elastic member that engages the relay member and the fixing member; the first elastic body is elastically deformed in the optical axis direction of the optical head main body, and the relay member of the second elastic body is elastically deformed in the direction of the optical axis of the optical head main body; By elastically deforming one end of the fixed member to rotate around an axis parallel to the optical axis, the optical head body moves in the optical axis direction of the optical head and in a direction perpendicular to the optical axis. An optical head device characterized by: