JPS60125939A - Objective lens driver - Google Patents

Abstract

PURPOSE:To obtain an objective lens driver containing a miniature support mechanism which is free from high-degree split resonance, by using a tension spring to connect a lens holder and a support member for the main body of an optical pickup. CONSTITUTION:Parallel V-shaped grooves 6 and 6' are provided to a lens holder 2 rectangularly to the optical axis X-X'. While conical holes 7 and 7' are provided to a support member 4 for the main body of an optical pickup at positions equal to the space between both V-shaped grooves. The knife edge parts at one side of two support plates 5 and 5' made of rigid matters of the same length are fitted into the grooves 6 and 6'. While the pivot parts at the other side of plates 5 and 5' are fitted into the holes 7 and 7'. A tension spring 8 is attached in parallel to the plates 5 and 5' between the holder 2 and the member 4. An objective lens 1 attached to the holder 2 has some spring power and can be shifted toward the optical axis. The lens 1 also some spring power with a line connecting bottom surface parts of both holes 7 and 7' defined as the center of revolution and therefore can be turned rectangularly to the optical axis.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an apparatus for optically writing or reading information (1<1"OZJ object lens driving device).

Conventional configuration and its problems Rotating a disk-shaped recording medium and correctly pasting or reading information into it/Secondly, disc displacement due to downward movement of the disk-shaped recording medium In order to correct 1-racking deviation due to eccentricity, etc., a device is provided that tracks and controls the objective lens in the direction perpendicular to the surface of the recording medium (in the optical axis direction) and in the radial direction (in the direction perpendicular to the optical axis). ing.

A conventional example will be explained below.

Normally, the device moves in two directions, the direction of the optical axis and the direction perpendicular to the optical axis, but for the sake of simplicity, the device will be explained using a device that moves only in one direction, the direction of the optical axis. FIG. 1 shows a typical conventional support mechanism. Reference numeral 1 denotes an objective lens that enters light into a minute Nubono+-KID and is fixed to a lens holder 2. Reference numerals 3 and 3 denote a pair of leaf springs arranged perpendicular to the optical axis, that is, parallel to the surface of the recording medium, and are firmly fixed to the optical hinoki anopu main body support part 4 and the lens holder 2.

With these various configurations, the objective lens 1 can be moved in parallel to the optical axis direction, and the focal position of the objective lens 1 can be controlled. However, this method of supporting the objective lens with two leaf plates has the following drawbacks.

(1) Higher-order split resonance of the handling blade occurs at higher frequencies, which adversely affects the servo characteristics.

? )'' In order to suppress the L resonance, a viscoelastic material is usually applied to the leaf spring (=1), but its temperature characteristics pose an industrial problem.

(3) Since repeated stress is applied to the leaf spring, it is necessary to design the stress to be small, which inevitably increases the length of the leaf spring, making it difficult to downsize the device, and the device itself. Become larger.

OBJECTS OF THE INVENTION The present invention eliminates the above-mentioned conventional drawbacks and provides an objective lens driving device that is compact, generates high-order split resonance, and has a strong support mechanism.

Structure of the Invention The present invention provides a parallel arrangement of lengths between a lens holder to which an objective lens is fixed and an optical pickup main body support member, one of which is in the shape of a knife or a plurality of pivots, and the other is in the shape of a biposu. Support plates of equal size are arranged parallel to the surface of the recording medium, and the support plates are sandwiched between grooves and holes provided in the lens holder and the support member, and connected by one or more tension springs. be.

Description of examples Examples of the present invention will be described below.

FIGS. 2A and 2B are a plan view and a front view of a functional model showing the basic configuration in the first embodiment of the present invention. In FIG. 2, reference numeral 1 denotes an objective lens, which is fixed to a lens holder 2. The lens holder 2 has an optical axis
Two parallel V-shaped grooves 6, 61 are provided at right angles to -Xt. Reference numeral 4 denotes an optical pickup main body support part 4, which has conical holes 7 at positions equal to the V-groove spacing of the lens holder 2.
, 7' are provided, and the depth of each hole is equal.

5.6' is a support plate made of a rigid body of equal length, with one side being a knife and the other being a pivot 1-; one knife part is fitted into the V grooves 6 and 6 of the lens holder 2, and the other is a pivot plate. The pivot portions are respectively fitted into the conical holes 7.7 of the support portion 4 of the optical amplifier main body. Therefore, the two supporting plates 6, 6' are parallel to each other and can rotate around the bottom of the V-shaped hole and the bottom of the circular Z1-shaped hole. Reference numeral 8 is a tensile force that connects the support plates 5 and 5' between the lens holder 2 and the optical pickup main body support part 4.
Installed in a row. In this case, the length of the cutout 11 is equal to or slightly shorter than the length of the support plates 6, 5'.

According to the configuration shown in "2", the lens holder 2 has a τ1
The eclipsed objective lens 1 can be moved with a slight spring force in the direction of the optical axis, that is, in the direction perpendicular to the surface of the recording medium (focal direction), while keeping the optical axis parallel. In the direction perpendicular to the optical axis direction of the flexible objective lens 1, that is, in the direction downward to the body surface during recording (tracking direction), the line connecting the bottoms of the conical holes 7° and 7' of the optical pickup main body support part 4 is rotated. The objective lens 1 can be rotated about the center with a slight spring force. The details of this operating principle will be explained with reference to FIGS. 4 and 6, and the second embodiment will first be explained with reference to FIG. 3.

FIG. 3(A) is a plan view of the second embodiment, and FIG. 3(B) is a front view. The second embodiment is the support plate 6 of the first embodiment,
5' is a support rod 5', 5''', the knife part is replaced with two pivot parts, and the tip of a highly rigid wire knife is formed into a spherical shape.

In this case, the V provided in the lens holder 2 of the first embodiment
The grooves are changed to 6'' and 6'' similar to the conical holes provided in the optical pickup main body support member 4.

With the configuration as described above, functions similar to those of the first embodiment can be obtained.

Next, the principle of operation of moving the 71-piece lens 1 in the optical axis direction, that is, in the focal direction, with some force will be explained with reference to the schematic diagram in FIG.

10d corresponds to the wooden support system 4, and 11 corresponds to the lens holder 2. The optical axis is parallel to the moon 11. 5,5
' and 8 are the support plate and the pulling/stretching springs explained above. The V-groove spacing and the conical hole spacing are equal to each other, and the lengths of the support plates 5 and 5' are also equal.The contacts a, b, c, and d are parallelograms, and the parts 10 and 11 are parallel even when deformed. be. Therefore, parts 4:) and 11 can move in the direction of the optical axis while remaining parallel to the optical axis. Now, regarding how to apply the tension knob 8, in Fig. 4(A), several examples of springs have lengths equal to the length of the support plate 6.5', that is, ad and bc.
In the case where the contact points between the pins 9, 9' and the tension spring 8 are provided on the line, in Fig. 4 (B)) , i.e. part, lν11 ad
This is a case where the large screw attachment contact point (on the line) is left as is, and the contact point between the pin 9' and the tension spring 8 is provided inside the line bc of the portion 4J10. In any case, when the subassemblies 10, 11 and the support plates 6, 5 are at right angles, the tension spring 8 is
In several cases, it is cut parallel to 5'.

Now, let us consider a case where the subassembly 11 in Fig. 4(A) is tilted (see the right figure). Even if the spring is tilted, the length of the support plate is 6.
, 5', the tension spring 8 and the support plates 5, 5' are parallel to each other, maintaining a parallelogram shape. Therefore, the tension spring 8
The elongation of is constant, and the tensile force F of the spring is always balanced with the sum of the drag forces from the support plate, so no restoring force is generated. The drag force from each support plate 5°5 is distributed depending on the position of the tensile force 8. Since the support plates 5, 5' are rigid bodies and do not deform, the portion A:A11, that is, the lens holder 2, can move in the optical axis direction while remaining parallel to the optical axis. What is important here is that the tension spring 8, in some cases, only elongates initially, and no further elongation occurs even if the lens holder 2, that is, the lens holder 2, is displaced in the optical axis direction.

Therefore, the structure is such that split resonance of the spring does not appear with respect to the movement of the objective lens 1, and the servo characteristics are also good. Figure 4 (
In the case of B), when the subassembly 11 is tilted (right figure), the tension spring 8
is tilted by an angle θ more than the support plates 5 and 6'. The component force of the tension force F of the spring on the support plates 5, 5' in the fossil direction and the sum of the drag from the support plates 5, 5' are always balanced, and the line of movement of the subassembly 11 generated by the angle θ is always balanced. The horn in the direction of the optical axis becomes a restoring force and generates a spring force. The spring force in this direction is not determined by the spring stiffness of the tension spring 8, but can be designed to an arbitrary value by adjusting the length of the armature and the initial tension force. 2, even if the tension spring 8 with a strong spring rigidity is used, the springiness of the restoring force generated when the objective lens 1 is moved can be made weak. Therefore, it is possible to make the objective lens 1 with a weak spring in only one direction, and to realize a strong support mechanism in the other direction, thereby limiting the degree of freedom of movement of the objective lens 1. As a result, objective lens 1
The optical axis can always be projected perpendicularly to the surface of the recording medium without causing the optical axis to tilt during movement. Also, Figure 4 (
As explained in A), since the elongation of the tension spring 8 is minute, the influence of the split resonance of the spring can be made to be almost zero. If the length of the spring is longer than that of the support plates 5, 5', once the spring is tilted, it will tilt even more, making it unusable.

Next, the operating principle of moving the objective lens 1 in a direction perpendicular to the optical axis direction, that is, in the l-racking direction with a slight spring force, will be briefly explained using the schematic diagram of FIG.

Similarly to FIG. 4, numeral 10 corresponds to the main body support part paulownia 4, and numeral 11 corresponds to the lens holder 2. The optical axis is parallel to the moon 11. Reference numerals 5, 6' and 8 are the support plates and tension springs having the same length and high rigidity.

Figure 6 (A) shows the connection of the tension spring 8 (= the line connecting the J-contact points to the bottoms of the V-grooves of the parts 11) in the same way as Figure 4 (A).
It is located on the line connecting the bottom of the conical hole of the member 10, that is, on the bC line. In this case, as long as the mounting contact position of the tension spring 8 is at the bottom of the conical hole of the member 10, which is the center of rotation, that is, on the line bc, the spring will not stretch even if the subassembly 11 is tilted as shown in the figure on the right. Therefore, restoring force that would cause the subassembly 11 to return to its original position is not generated.

5(B) is the same as in FIG. 4), the length of the spring is shorter than the length of the support plates 5, 5, that is, the length of the support plate 11. L
Splash catcher on d wire (leave -1 contact as is, remove part 4-1)
This is a case where a contact point between the bottle 9) and the tension spring 8 is provided on the inside of the bc cotton wire 0. In this case, the contact point of several springs in the part control ad line "2" is e, and the rotation center b of part control 11 is from e.
Let the length at point C 1 be β. Similarly, let f be the contact point of the part 10 and let the length from e to f-4 be e'.

Now, when tilting part 11 as shown in the figure on the right, part 4 and part 11
are the radius of rotation e with the line connecting bc as the center of rotation, respectively
3JQ Ripay 8 is the turning radius β with f as medium and U.
', but here the rotation radius of part 11 is 4
From (bC-e), the rotation radius of the tension spring 8 is 1' (f~e
), () As the tightening part 4:/I'11 rotates, the pull 'rJ'+rihane 8 is slightly extended. Therefore, a restoring force is generated in the subassembly 11 that tries to pull it back in a direction perpendicular to the optical axis force plane. This restoring force works in the trench where e is located on the extension line connecting bC and f. That is, the tension spring 8 will work until it stabilizes at the minimum elongation position. However, this restoring force is not determined only by the spring rigidity of the tension spring 8 as explained in Fig. 4, but can be designed to any value by adjusting the length and initial tension force. If the length of the spring is made longer than that of the support plates 6, 5', once the spring is tilted, it will tilt even more, making it impossible to use it as shown in Fig. 4.

As explained above, the support mechanism of the present invention supports the objective lens 1 in the optical axis direction (focus direction).
can be translated in parallel with each rotation center,
In a direction perpendicular to the optical axis (tracking direction), it can be rotated about the bc line as the rotation center.

FIG. 6 shows an embodiment of the objective lens driving device in which the support mechanism of the present invention is provided with two independent driving mechanisms in the focusing direction and the 1-racking direction.

(A) shows its plan view, and (B) shows its front view.

12 is a focus drive coil fixed to the lens holder 2. A focus drive magnet 13 is fixed to a U-shaped yoke 14 for focus drive.
is fixed to the optical pickup body. Also 15,1
6.17 is a similar 1-racking coil, magnet, and yoke that is front-illuminated in a direction perpendicular to the focus direction.

With the above configuration, the current flowing through each coil causes the object lens 1 to move 2!1Il orthogonally to each other.
It is driven in 11 directions.

Effect of the invention The present invention configured as described above has the following effects.

(1) The restoring force of the lens can be freely designed by selecting the fulcrum position of the tension spring, the initial tension force, and the spring rigidity.

(2) Since the tension spring hardly expands or contracts with respect to the displacement of the 2j object lens, there is no high-order split resonance caused by conventional leaf springs, etc., resulting in good servo characteristics.

(3) Since there is no need to use a viscoelastic material such as rubber to prevent split resonance caused by the conventional plate spring type, reliability in terms of temperature characteristics, humidity characteristics, latitude changes, etc. is improved.

(4) In the conventional leaf spring type, the arm length of the leaf spring was inevitably long in order to design the repetitive stress to be small.
Since the present invention uses a rigid support plate, its length can be designed to be short, and the device can be miniaturized.

(6) The distance between the center of the objective lens and the outside of the objective lens driving device can be shortened, and the degree of freedom in setting H1 of the disk morph diameter can be increased.

[Brief explanation of the drawing]

Figure 1 is a perspective view showing a typical support mechanism in the conventional example;
Figures (A) and (B) are a functional model 1'1' and a top view showing the basic configuration of the support mechanism in the first embodiment of the present invention, and Figure 3 (A) and Figure 3 (b) are the top views of the functional model representing the basic configuration of the support mechanism in the first embodiment of the present invention. FIG. 4 is a plan view and front view of a functional model showing the basic configuration of the support mechanism in the second embodiment of the present invention, FIG. 6(A) and 6(B) are schematic diagrams for explaining the principle of operation of the support mechanism of the present invention in the tracking direction, and FIGS. FIG. 2 is a plan view and a front view of an embodiment of a lens driving device. 1... Objective Rennes, 2... Lens holder,
5.5'...Support plate, 6,61...7-shaped groove, 7゜71...circular hole, 8...pull 1 circular spring, 12. ...Focus drive coil, 13.
···magnet.

Claims (1)

[Claims] (1) The objective lens of the device 11' for optically writing information onto the recording medium 2, and a plurality of objects parallel to the optical axis of the object 11' in the direction of the curved angle. A lens holder with grooves or conical holes in the lens holder, and conical holes with equal intervals to the grooves or holes in the lens holder.
a pair of parallel supporting plates of equal length, one of which has a knife shape or a plurality of pivot shapes and the other of which has a pivot shape; one or more tension springs connected by the support plate, and at least two independent coils wound around the lens holder in directions perpendicular to each other; An objective lens driving device characterized in that a water-immersed magnet is arranged so that the objective lens can be moved one step at a time in two axial directions orthogonal to each other by a current flowing through the coil. ?) The length of the tension springs is equal to or slightly shorter than the length of the support plate by χ1, and the tension springs have a length (a part of which is rotatable). [Force described in item 1] Actual lens drive device.