JPH0644583A - Objective lens electromagnetic driving device for optical information recording and reproducing device - Google Patents

Abstract

PURPOSE:To obtain a lightweight, small-sized objective lens holder and the thin elastic support structure for the objective holder. CONSTITUTION:The objective holder 21 is provided with a cylindrical part 21 holding an objective lens 16 and a couple of wing parts 21b extended radially and symmetrically from the cylindrical part 21a in the tracking direction of an optical disk. In both the end parts of the couple of wing parts 21b separated in the tracking direction, connection holes 27a and 27b for suspension wires are pierced at a distance in the focusing direction of the objective. One-end parts of four suspension wires 32a and 32b are fixed in the upper and lower suspension wire connection holes 27a and 27b of both the end parts of the couple of wing parts and the other-end parts of the wires are fixed to a support block 31 being a fixed member on a carriage.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical information recording / reproducing apparatus for optically writing or reading information to / from an optical disk, and more particularly to an electromagnetic driving apparatus for its objective lens.

[0002]

2. Description of the Related Art Generally, an optical disk device such as a magneto-optical disk device is provided with a carriage movable in a radial direction (tracking direction) of the optical disk, and the carriage is elastically movable in a focusing direction and a tracking direction. Holds the objective lens. Then, in order to drive this objective lens in the focusing direction and the tracking direction, the focusing and tracking coils are provided in the lens holder holding the objective lens, while the carriage is provided with these coils and the magnetic force forming the electromagnetic drive circuit. A circuit is provided. The focusing and tracking coils are driven by an electromagnetic drive circuit to drive the objective lens holder, and a current is applied in such a direction and intensity that the laser light focused by the objective lens is correctly focused on the recording track. .

In this objective lens electromagnetic drive device, the carriage moves in the radial direction of the optical disk, and the objective lens holder moves on the carriage. For high speed access and high precision focusing and tracking, it is desirable that the carriage and objective lens holder be as light as possible. For example, in the structure in which the objective lens holder is supported via the suspension wire, if the weight of the objective lens holder is large, the acceleration performance will deteriorate.

[0004]

It is an object of the present invention to reduce the weight and size of an objective lens holder in a structure in which the objective lens holder is supported by a suspension wire. Further, the elastic supporting structure of the objective lens holder is thinned and the objective lens is An object of the present invention is to obtain a structure in which an optical axis is less likely to tilt when a holder is electromagnetically driven at high acceleration. It is another object of the present invention to provide a device that uses a suspension wire as a power supply line to a coil and has almost no increase in weight for wiring.

[0005]

SUMMARY OF THE INVENTION According to the present invention, an objective lens holder is provided with a tubular portion for holding the objective lens and a pair of wing portions extending radially and symmetrically from the tubular portion in a tracking direction, Suspension wire connection holes are formed at both ends of the pair of wing portions, which are separated from each other in the tracking direction, so as to be separated from each other in the focusing direction of the objective lens. It is characterized in that it is fixed to the upper and lower suspension wire connection holes at both ends of the wire, and the other end of the wire is fixed to a support block which is a fixing member on the carriage.

According to the analysis by the present inventor, the inclination of the optical axis of the objective lens caused by the torque caused by the accumulated error during electromagnetic driving at high acceleration is the same as the mechanical properties of the four suspension wires. When this is done, the larger the interval, the more it can be suppressed. Further, in the optical information recording / reproducing apparatus, it is particularly desirable to reduce the thickness.
Therefore, the installation interval a of the four suspension wires in the tracking direction is equal to the installation interval b in the focusing direction.
It is preferable to set it larger. According to the structure of the objective lens holder of the present invention, since the wing portion is extended from the objective lens in the tracking direction, the installation interval a can be increased without wasting space.

Further, a focusing coil is fixed to each of the pair of wings of the objective lens holder,
A tracking coil is fixed to each of the outer surfaces of the tubular portion in the direction orthogonal to the tracking direction. Then, this objective lens holder is made of an injection-molded product of a synthetic resin material, and a printed circuit for electrically connecting the suspension wire connection hole to the focusing coil and the tracking coil is directly provided on the objective lens holder. Once formed, the four suspension wires can be used as power feed lines by simply soldering the suspension wires inserted in the connection holes to this printed circuit.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below with reference to illustrated embodiments. As shown in FIG. 9, a pair of rails 1 oriented in the radial direction are formed on the lower surface of the optical disc 11 which is rotationally driven.
2 is provided, and a carriage 13 is movably supported on the rail 12. In the carriage 13, a prism 15 that vertically reflects upward the laser light L incident from the stationary fixed optical system 14 along the rail 12 and a laser light reflected by the prism 15 are connected to the recording surface of the optical disk 11. Objective lens 16 for imaging and this objective lens 1
An electromagnetic drive mechanism 20 that drives 6 in the focusing direction F and the tracking direction T is mounted.

The present invention is characterized by the electromagnetic drive mechanism 20, particularly the objective lens holder 21 for holding the objective lens 16 and its elastic support mechanism. As shown in FIGS. 1 to 5, the objective lens holder 21 includes a cylindrical portion 21a for holding the objective lens 16 in the center thereof, and a pair of symmetrical cylindrical portions 21a are provided in the opposite radial direction from the cylindrical portion 21a. Wing portion 21b is provided. That is, the pair of wing portions 21b are located in a straight line with the tubular portion 21a interposed therebetween, and the direction thereof coincides with the tracking direction T. A coil housing through hole 21c is formed in each of the pair of wing portions 21b. Focusing coils 33 are inserted and fixed in the coil housing through holes 21c, respectively. The winding plane of the focusing coil 33 faces the same direction as the extension plane of the wing portion 21b, and the focusing coil 33 is provided with a straight portion 34L parallel to the tracking direction.

On the other hand, on the outer surface of the tubular portion 21a, coil supporting protrusions 21d and 21e are formed on both surfaces orthogonal to the extension direction of the wing portion 21b. The upper coil support protrusion 21d fits in the center of the tracking coil 34, and the lower coil support protrusion 21e supports the lower surface of the tracking coil 34. The winding plane of the tracking coil 34 is the focusing coil 3
The tracking coil 34 has a straight line portion 34L parallel to the winding plane 3 and parallel to the focusing direction F.
It is included.

The objective lens holder 21 is made of an injection-molded product made of a resin material, and a pair of focusing coils 33 and tracking coils 34 are connected in series on the surface of the objective lens holder 21. 33, a printed circuit for energizing the tracking coil 34 is directly formed. 3 to 5 show the printed circuit with hatching. A first connecting portion 26a for connecting the pair of focusing coils 33 is formed on the surface of the tubular portion 21a so as to surround the one coil supporting protrusion 21d, and the lower portion of the tubular portion 21a is connected to the lower end surface. Is connected to the second connecting portion 2 for connecting the pair of tracking coils 34.
6b is formed. Further, a current supply portion 26c to the focusing coil 33 and a power supply portion 26d to the tracking coil 34 are formed in each of the pair of wing portions 21b. Each pair of the current supply portion 26c and the power supply portion 26d is extended to suspension wire connection holes 27a and 27b provided at the upper end and the lower end of the extended end of the coil housing through hole 21c, respectively.

The one end connecting wires 33a of the pair of focusing coils 33 shown in FIG. 1 are respectively connected to the first connecting portion 26a.
And the other end power supply line 33b is soldered to the corresponding current supply part 26c. Similarly, the one end connection line 34 of the pair of tracking coils 34
a is soldered to both ends of the second connection portion 26b, and the other end power supply line (not shown) is soldered to the corresponding power supply portion 26d. Then, one ends of the upper and lower suspension wires 32a and 32b are inserted and soldered into the suspension wire connection holes 27a and 27b, respectively. The pair of suspension wires 32a form a power supply line for the pair of focusing coils 33 connected in series, and the pair of suspension wires 32b form a power supply line for the pair of tracking coils 34 connected in series. Constitute.

The printed circuits 26a to 26e of the objective lens holder 21 described above are technologies (MID method, Molded Interconnec) for directly providing printed wiring on an injection-molded product made of a resin material.
option device). The MID method includes application of tampo printing to a three-dimensional surface, application of printing technology to a three-dimensional surface, application of light drawing technology to a three-dimensional surface, application of mechanical drawing technology to a three-dimensional surface, microscopic application to a three-dimensional surface. The application of drawing technology by sandblasting, etc. are known.

FIG. 13 shows an example of the process of the MID method by applying the light drawing technique of. First, in the injection molding process 50, the objective lens holder 21, the support block 31, and the sensor holder 41 are injection-molded, the injection-molded product is subjected to the etching treatment 51 and the activation treatment 52, and then subjected to the electroless plating treatment 53. , Apply uniform plating to the entire molded product. Next, a photoetching resist film is applied on the plating layer in a resist applying step 54, and then a required circuit pattern image is formed in a circuit imaging step 55 using light. This circuit pattern image is exposed as a circuit pattern through electrolytic copper plating treatment 56, electrolytic nickel plating treatment 57, and protective plating treatment 58, and then an unnecessary residual resist film is removed by a resist peeling treatment 59 to eliminate It is completed by the final process of the flash etching process 60 of electrolytic plating.

On the other hand, on the carriage 13, the focusing coil 33 and the tracking coil 34 are provided.
Together with this, the magnetic circuit that constitutes the electromagnetic drive circuit is fixed. This magnetic circuit includes a permanent magnet 22 for focusing.
It is composed of an F and tracking permanent magnet 22T and a yoke member 23 made of a magnetic material. The focusing permanent magnets 22F are provided in pairs so as to sandwich the focusing coils 33 of the pair of wing portions 21b, respectively, and the tracking permanent magnets 22T are
A pair is provided so as to be located on both sides of the tubular portion 21a so as to sandwich the pair of tracking coils 34. 10 to 12 show the focusing permanent magnet 2
The polarities of 2F and the permanent magnet 22T for tracking are shown. This polarity is such that the linear portions 33L and 34L (current flowing through) of the focusing coil 33 and the tracking coil 34 are orthogonal to the magnetic flux lines Φ formed by the focusing permanent magnet 22F and the tracking permanent magnet 22T, which are schematically shown in the figure. As described above, the forward and reverse currents flowing in the straight line portion 33L generate forward and reverse driving forces in the focusing direction F in the objective lens holder 21, and the straight line portion 34L.
Due to (current flowing through), forward and reverse driving forces in the tracking direction T are generated in the objective lens holder 21.

The focusing control electromagnetic drive circuit including the focusing coil 33 and the focusing permanent magnet 22F and the tracking control electromagnetic drive circuit including the tracking coil 34 and the tracking permanent magnet 22T are provided so as not to interfere with each other. Has been. That is, the driving current in the tracking direction T is not generated in the objective lens holder 21 by the current flowing through the focusing coil 33, and similarly, the tracking coil 3 is driven.
The driving current in the focusing direction F is not generated in the objective lens holder 21 by the current flowing in 4. As described above, the electromagnetic driving circuits do not interfere with each other because the wing portion 21b is projected from the cylindrical portion 21a of the objective lens holder 21 and the focusing coil 33 is supported by the wing portion 21b.
The tracking coil 34 has an additional effect of being provided directly on the outer surface of the tubular portion 21a. With this mutual non-interference electromagnetic drive circuit, the tracking direction T,
Independent and highly accurate control of the focusing direction F is possible.

A yoke member 23 for supporting the focusing permanent magnet 22F and the tracking permanent magnet 22T.
Is a counter magnetic shield wall 23a positioned parallel to the optical disk 11.
And substantially perpendicular to the opposing magnetic shield wall 23a, the opposing magnetic shield wall 23
It is composed of a single member integrally including a plurality of yoke walls 23b extending from the peripheral edge of a to the carriage 13 side and a plurality of mounting flanges 23c extending from the yoke wall 23b on the carriage 13. A laser beam transmission hole 24 is formed in the opposing magnetic shield wall 23a as a moving space of the objective lens 16 (a space through which the laser light L passes). The mounting flange 23c is fixed to the carriage 13 with a mounting screw 25. A support block 31 is fixed to the yoke member 23 with a fixing screw 30 (FIG. 7).

The other ends of the suspension wires 32a and 32b are fixed to the support block 31. The objective lens holder 21, that is, the objective lens 16, can be elastically displaced in the focusing direction F and the tracking direction T by the elasticity of the suspension wires 32a and 32b. The suspension wire holding hole 31a of the support block 31 is sufficiently larger than the diameter of the wires 32a and 32b,
A damper material (eg, gel) that gives a suitable damping resistance to the wires 32a and 32b is filled therein.

The installation distance a in the tracking direction between the suspension wires 32a and 32b is set to be sufficiently larger than the installation distance b in the focusing direction. The inclination of the optical axis of the objective lens 16 when electromagnetically driving the objective lens holder 21 is preferably as small as possible. According to the analysis by the present inventor, if other conditions are the same, (a ² + b
^The larger the value ² ) / 4, the less likely the optical axis will tilt. In the present invention, a> b is set in order to shorten the length in the focusing direction and achieve thinness.

In the electromagnetic drive mechanism 20 having the above structure, a focusing driving current is applied to the focusing coil 33 via the pair of suspension wires 32a, and the tracking coil 34 is fed to the tracking coil 34 via the pair of suspension wires 32. A drive current for tracking is given. When a driving current is applied to the focusing coil 33, the objective lens holder 21, that is, the objective lens 16 is driven in the forward and reverse directions in the focusing direction F in accordance with the direction and size of the focusing coil 33, and the driving current is applied to the tracking coil 34. Then, depending on its direction and size,
The objective lens 16 is driven forward and backward in the tracking direction T. Therefore, by controlling this drive current, the laser light L focused by the objective lens 16 can be accurately traced on the recording track on the optical disc 11.

[0021]

As described above, according to the present invention, the weight and size of the movable objective lens holder, which is the movable member on the carriage, can be reduced, and the four suspension wires that elastically support the objective lens holder are Since one end is fixed to the upper and lower suspension wire connection holes at both ends of the pair of wings of the objective lens holder, a flat support structure in the focusing direction can be obtained. That is, according to this structure, the installation interval a of the four suspension wires in the tracking direction can be set larger than the installation interval b in the focusing direction, so that the inclination of the optical axis of the objective lens during high acceleration electromagnetic driving can be set. The thickness can be reduced while suppressing effectively. Further, by providing a printed circuit for connecting the suspension wire connection hole and the coil on the objective lens holder, the weight for electric wiring can be reduced, and further, the movable member including the objective lens holder can be reduced in weight and size. You can

[Brief description of drawings]

FIG. 1 is a perspective view of essential parts showing an embodiment of an objective lens electromagnetic drive device of an optical information recording / reproducing apparatus according to the present invention.

FIG. 2 is a perspective view of a single objective lens holder according to the present invention.

FIG. 3 is a view on arrow P of FIG.

FIG. 4 is a view on arrow Q of FIG.

FIG. 5 is a bottom view of FIG.

FIG. 6 is a perspective view showing another embodiment of the objective lens electromagnetic drive device of the optical information recording / reproducing apparatus according to the present invention.

7 is a sectional view taken along the line AA of FIG.

8 is a cross-sectional view taken along the line BB of FIG.

FIG. 9 is a perspective view showing a main part of an optical information recording / reproducing apparatus.

FIG. 10 is a plan view showing the polarities of the tracking permanent magnets of the electromagnetic drive circuit.

FIG. 11 is a front view showing the polarity of the focusing permanent magnet of the electromagnetic drive circuit.

FIG. 12 is a perspective view showing a positional relationship between permanent magnets and coils of an electromagnetic drive circuit.

FIG. 13 is a block diagram showing an example of a process of forming a printed circuit on an objective lens holder by the MID method.

[Explanation of symbols]

F Focusing direction T Tracking direction L Laser light 11 Optical disc 12 Rail 13 Carriage 14 Fixed optical system 15 Prism 16 Objective lens 20 Electromagnetic drive mechanism 21 Objective lens holder 21a Cylindrical part 21b Wing part 21c Coil storage through hole 21d 21e Coil support Protrusion 22F Focusing permanent magnet 22T Tracking permanent magnet 23 Yoke member 27a 27b Suspension wire connection hole 30 Fixing screw 31 Support block 32a 32b Suspension wire 33 Focusing coil 34 Tracking coil a Suspension wire tracking spacing b Suspension wire Installation interval in the focusing direction

Claims (4)

[Claims] 1. A carriage movable in a radial direction of an optical disk; and an objective lens for focusing a laser beam on the optical disk, and elastically movable on the carriage in a focusing direction and a tracking direction of the optical disk. In an optical information recording / reproducing apparatus having an objective lens holder supported by a lens holder, a cylindrical portion holding the objective lens in the objective lens holder, and a radial symmetry from the cylindrical portion in the tracking direction. And a pair of wing portions extending in the direction of the suspension lens. The suspension wire connection holes are formed at both ends of the pair of wing portions so as to be vertically spaced apart from each other in the focusing direction of the objective lens. Insert one end into the upper and lower suspension wire connection holes on both ends of this pair of wings. Together are fixed, the other end of the wire, the objective lens electromagnetically driving device of an optical information recording and reproducing apparatus, characterized in that fixed to the support block is a fixed member on the carriage. 2. The objective lens electromagnetic drive device according to claim 1, wherein an installation interval a of the four suspension wires in the tracking direction is set to be larger than an installation interval b in the focusing direction. 3. The focusing coil according to claim 1, wherein the focusing coil is fixed to each of the pair of wing portions of the objective lens holder, and the focusing coil is fixed to both outer surfaces of the cylindrical portion in a direction orthogonal to the tracking direction. Each is an objective lens electromagnetic drive device to which the tracking coil is fixed. 4. The objective lens holder according to claim 3, wherein the objective lens holder is made of an injection-molded product of a synthetic resin material, and the suspension wire connection hole, the focusing coil and the tracking coil are electrically mounted on the objective lens holder. An objective lens electromagnetic drive in which a printed circuit for connection is directly formed.