JPH07226056A - Head device and supporting substrate thereof - Google Patents

Abstract

PURPOSE:To provide a head device and a supporting means with simple structures, excellent for assembling workability and provided with a vibration characteristic effective for servo control. CONSTITUTION:An optical head part 7 is supported by flexible printed circuit boards 5A, 5B in a state floating elastically. A tracking coil 9 and a focusing coil are provided on the optical head part 7 as movable pieces, and a magnet 10 is provided opposing to them as a stator. A driving current for controlling the optical head part 7 in the biaxial directions is supplied through wiring on the circuit board 5B, and further, an optical information signal read out by the head part 7 is led out through the wiring on the circuit board 5A.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a head device effective for supporting an optical head or the like used for recording and / or reproducing information on an optical recording medium such as an optical disk and for controlling the position of the optical head. And a head support substrate.

[0002]

2. Description of the Related Art Conventionally, a signal beam is irradiated onto a signal recording surface of an optical disk which is mounted on a disk rotation driving device and rotated, and an information signal recorded on the optical disk is read or a predetermined information signal is written on the optical disk. In this case, an optical pickup device is used. This optical pickup device has a light source such as a semiconductor laser element, and transmits a light beam generated by the light source through a predetermined optical device such as a collimator lens or a beam splitter and an objective lens to an optical disc as an optical recording medium. In addition to condensing on the signal recording surface, a light beam reflected from the signal recording surface is detected by a photodetector, and an information signal is written in or read from the signal recording surface. Proposed.

In the above-mentioned optical pickup device, the objective lens is driven by an electromagnetic drive force to be displaced in two axial directions of the optical axis direction (that is, the focus direction) and the direction orthogonal to the optical axis (that is, the tracking direction). Driven by a lens driving device, the light beam is focused on the signal recording surface of the optical disc to accurately scan the recording track.

As the above-mentioned objective lens driving device, there are those disclosed in Japanese Utility Model Laid-Open No. 1-252424 and Japanese Patent Laid-Open No. 2-179932. Here, there is a lens bobbin that supports the objective lens, and the lens bobbin is supported by a support arm composed of four round bars or a support arm that is a combination of parallel leaf springs that are orthogonal to each other. Then, based on the detection output of the photodetector, the lens bobbin is driven and displaced via the support arm, and so-called focus servo and tracking servo are realized. The focus servo controls so that the light beam projected on the signal recording surface is always accurately focused on the signal recording surface even when so-called surface wobbling occurs when the optical disc is rotationally driven. . Therefore, when the focus servo is operated, the objective lens is driven and displaced so that the distance between the objective lens and the optical disk is always kept at a predetermined value. In addition, the tracking servo is controlled so that the beam spot where the light beam is focused accurately traces the recording track formed on the signal recording surface even if so-called center wobbling occurs when the optical disc is rotationally driven. To do.

[0005]

According to the above-mentioned conventional objective lens driving device, in the case of the support arm composed of four round rods, it is necessary to attach each round rod to the lens bobbin, which is complicated in structure and manufactured. Becomes complicated. In addition, it is necessary to supply a drive current for control to the focus coil and tracking coil provided on the lens bobbin that is a movable part, but it is necessary to provide a connecting wire between the lens bobbin and the fixed part, and the surrounding space. Is crowded. Further, as the connecting line, it is necessary to use an extremely thin litz wire that can be displaced following the lens bobbin without giving a large load to the movable part of the objective lens. With such a wire, the workability is poor because the mechanical strength is not sufficient.

In a device in which a printed wiring board is attached to a supporting arm formed by combining parallel leaf springs orthogonally to each other, and an optical head is provided on this board, resonance of the printed wiring board itself appears and focus or tracking servo is performed. It may not converge. Further, the mechanism for fixing the printed wiring board to the support arm is complicated, resulting in an increase in the number of parts and a deterioration in the assembly workability.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a head device and a supporting substrate for the head device, which can simplify the overall structure, improve the assembly workability, and obtain the stability of the control operation.

[0008]

SUMMARY OF THE INVENTION The device of the present invention comprises a head portion, a head portion supported at one end side, formed to be curved midway, and the other end side being attached to a fixed portion and elastically Supporting means by a flexible printed wiring board that holds the head part in a floating state and integrally has wiring for obtaining electrical connection to the head part from a fixed part side; and a supporting means provided on the head part. And a stator for controlling the position of the head part by applying a magnetic field to the mover.

In the substrate of the present invention, a wiring pattern of a conductor such as a copper foil is formed on at least one side surface of a flexible rectangular film substrate, and the conductor is a spring material, and the thickness direction is The semicircular shape is curved so that the radial directions coincide with each other, and the shape is a steady shape. The direction connecting both ends of the semicircular shape and the direction connecting the center of the semicircular shape and the center of the semicircular circumference. It is displaceable in two axial directions, and a head part driven by an electromagnetic mover is provided at one end, and the other end is used by being fixed to a fixed part.

[0010]

By the above means, the flexible printed wiring board has an electric connection between the head portion and the fixed portion and also has a function as an arm for supporting the head portion. It is easy and the electrical connection is accurate. Further, the flexible printed wiring board is curved in the middle even if it is a single member, and functions as an actuator that is displaced in the vertical direction (focus direction) and the horizontal direction (curved deformation direction = tracking direction), that is, biaxial directions. The vibration characteristics are stable and effective for servo control.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an assembled state of an embodiment of the present invention, FIG. 2 shows an exploded perspective view, and FIG. 3 is an operation explanatory view. Further, FIG. 4 shows the structure of the flexible wiring board 5 peculiar to the present invention.

First, the entire apparatus will be described. The integrated optical head unit 7 for recording and / or reproducing information signals on / from the optical disc includes an objective lens 6, a semiconductor laser element, a collimator lens, a beam splitter, a prism, a hologram optical element, a photodetector (not shown), etc. Is disposed inside. The integrated optical head unit 7 is unitized based on a frame, has the objective lens 6 on the upper surface, and has a focus coil 8 on the side surface (thick surface). In addition, the tracking coils 9 are provided at a plurality of positions (four symmetrical positions) on the side surface. Flexible printed wiring boards 5A and 5B are arranged symmetrically at the front-rear direction (tracking control direction) ends of the integrated optical head unit 7. The description will be given on behalf. The frame of the optical head portion 7 is an engineering plastic material having high rigidity and a low linear expansion coefficient.

One end of the flexible printed wiring board 5A is fixed to the base material of the optical head portion 7 by the fixing screw 14a through the guide plate 12 and the positioning hole 16a. The other end of the flexible printed wiring board 5 is fixed to the magnetic yoke 11 by the fixing screw 14b through the pressing plate 13 and the positioning hole 16b. At this time, the flexible printed wiring board 5 is curved and supports the integrated optical head portion 7 so as to float.

The magnetic yoke 11 is a frame body composed of left and right standing portions and a lower portion when viewed from the tracking direction, and the magnets 10 are provided on the left and right standing portions. The integrated optical head unit 7 is arranged inside the magnetic yoke 11 that is a frame body, and the tracking coil 9 and the like are opposed to the magnet 10. The electrical connection lines required for the tracking coil 9, the focus coil 8 and the integrated optical head unit 7 are flexible printed wiring boards 5A and 5B.
Are connected through the wiring pattern. Therefore,
When a drive current is supplied to the focus coil 8 and the tracking coil 9, the optical head 7 is driven in the arrow XX direction (tracking control direction) and the YY direction (focus control direction) (see FIGS. 1 and 3). can do.

FIG. 3A shows a mechanically neutral state. Flexible printed wiring boards 5A, 5B
The optical head 7 is in a levitated state by the elastic force of. Due to the weight of the optical head unit 7 and the offset currents of the focus coil 8 and the tracking coil 9, the flexible printed wiring boards 5A and 5B are positioned at the center position C.
Deflection is 1, C2, and radius of curvature ρN.

FIG. 3 (B) shows a state in which the lens is driven by tracking control and moved from the neutral position. By supplying the tracking control current to the tracking coil 9, the movement of the optical head unit 7 is controlled, for example, in the arrow FT direction (the direction orthogonal to the optical axis of the objective lens 6). At this time, the flexible printed wiring boards 5A, 5B
Is bent by the guide plate 12 and the magnetic yoke 11, so that it bends with a radius of curvature ρT that is almost equal to the radius of curvature ρN at the neutral position in FIG. 3A, and its center positions C1 and C2 are the tracking force from the neutral position. Move in the direction.

In FIG. 3C, focus control is performed,
The state where the neutral position has moved is shown. By supplying the focus control current to the focus coil 8, the optical head portion 7 is driven and displaced in the direction of the arrow FF in the drawing (the optical axis direction of the objective lens 6), that is, the focusing direction. At this time, since the flexible printed wiring boards 5A and 5B are regulated by the guide plate 12 and the magnetic yoke 11,
Deflection with a radius of curvature ρF smaller than the radius of curvature ρN at the neutral position in FIG. 3A, and the center positions C1 and C2 are shown in FIG.
Moves outside the position of. On the other hand, when the direction of the focusing force is opposite, that is, when the optical head portion 7 and the magnetic yoke 11 are driven in the direction in which they are separated from each other, the flexible printed wiring boards 5A and 5B are moved to the neutral position of FIG. Deflection with a radius of curvature ρF greater than the radius of curvature ρN of
The center positions C1 and C2 move inward from the position shown in FIG.

FIG. 4 shows the structure of the flexible printed wiring boards 5A and 5B described above.
Will be described as a representative. FIG. 4A shows one surface, FIG. 4B shows the other surface, and FIG. 4C shows a structural example seen from a cross section. This board basically has a flexible rectangular film base material on which a wiring pattern of a conductor such as a copper foil is formed on at least one side surface, and the conductor is used as a spring material. The steady shape is a state of being curved in a semicircular shape so that the two coincide with each other. It is displaceable in two axial directions, a direction connecting both ends of the semicircular shape and a direction connecting the center of the semicircular shape and the center of the circumference of the semicircular shape,
A head part driven by an electromagnetic mover is provided at one end, and the other end is used by being fixed to a fixed part.

Specifically, a plurality of wiring patterns used as spring materials are provided on both sides of the flexible synthetic resin film substrate 1, for example, 2a, 2c, 2 are provided on one side.
e, 2b, 2d, etc. are formed on the other surface. The wiring patterns 2a, 2b, 2c, 2d, etc. have a plurality of land portions 4a, 4b, 4c, 4d, 4e, etc., which are provided at both ends thereof and are shown as shaded portions to be coil soldering points, and through holes 15a, It is electrically coupled through 15b, 15c, 15d, 15e and the like. Further, the aforementioned positioning holes 16a and 16b are also formed. The upper surface of the wiring pattern is covered with the insulating cover film 3.

As a material for a plurality of wiring patterns and the like utilized as a spring material, an electric conductor such as copper, beryllium copper and phosphorous rust copper is used. Further, as the film substrate 1 and the insulating cover film 3, those having a base material of a synthetic resin film having heat resistance and not so high in rigidity are used. For example, synthetic resins such as polyimide, polyamide-imide, aromatic polyamide (heat resistant nylon), fluororesins such as polytetrafluoroethylene, polyester resins such as polyparabanic acid and polyethylene terephthalate are used.

The above-mentioned two flexible printed wiring boards 5A and 5B are preferably the same so as to obtain good focusing vibration characteristics and tracking vibration characteristics. However, the basic idea of the present invention is that only one side is provided. Of course, the other of the substrates may be used as a simple supporting means. Further, as described above, since the flexible printed wiring boards 5A and 5B are members that are displaced in both biaxial directions of focus and tracking, the resonance frequency is constant as a whole and partial harmful resonance is prevented from occurring. You can That is, if the support member in the focus direction and the support member in the tracking direction are separate members, the resonance frequencies are different from each other, which may cause harmful resonance, but this system does not pose such a risk.

In the above embodiment, the fixing structure of the flexible printed wiring boards 5A, 5B and the optical head portion 7 and the magnetic yoke 11 uses the fixing screws.
Not limited to this, other fixing means may be used.

FIGS. 5A and 5B show another example of the mounting structure of the flexible printed wiring boards 5A and 5B, the optical head portion 7 and the magnetic yoke 11.
The frame (base material) of the optical head portion 7 is an engineering plastic material having high rigidity and a low linear expansion coefficient, and is in a state where it is firmly integrally molded and fixed to one end of the flexible printed wiring boards 5A and 5B by injection molding. .
The actuator base 17 to which the other ends of the flexible printed wiring boards 5A and 5B are attached is also an engineering plastic material having high rigidity and a low linear expansion coefficient, and has a U-shaped magnetic yoke 11 and the flexible printed wiring board 5A. It is firmly and integrally fixed to the other end of 5B by injection molding.

The flexible printed wiring board described above is not limited to the support of the head device, but is an effective board for supporting other floating members and for electrically connecting the movable portion and the fixed portion. . Further, in the above embodiment, the description has been made assuming that the wiring is provided on both sides, but a flexible printed wiring board having pattern wiring on only one side may be used. In the embodiment described above, the optical head unit 7 is provided with the focus coil 8 and the tracking coil 9. However, the invention is not limited to this, and a coil unit as a mover may be provided from the beginning at one end of the flexible printed wiring board.

In the above embodiment, the flexible printed wiring boards 5A and 5B were used. Therefore, when the focus and tracking control signals are supplied through the signal line of one flexible printed wiring board and the signal line of the other flexible printed wiring board is used for the information signal related to the optical disc, Interference of signals with each other and mixing of noise are completely prevented, and accurate control and signal transmission are possible, thus improving reliability. Although there are several methods of separation, for example, a method in which the detection signal from the photodetector is on one substrate side and the drive current for controlling the semiconductor laser element and the drive current of the drive coil are on the other substrate side There is also. By doing so, it is possible to prevent noise from the drive current side from being mixed into the detection signal.

According to the above apparatus, it is not necessary to use a connecting means such as a litz wire or a new printed wiring board, the number of parts can be reduced, the structure can be simplified, and the assembling work can be facilitated.

Further, by using symmetrically the printed wiring board having the same structure in which a wiring pattern of a conductor such as a copper foil is formed on at least one side surface, symmetrical focusing and tracking vibration characteristics can be obtained. Obtainable. Furthermore, since the flexible printed wiring board formed in a rectangular shape is curved, it can be elastically displaceable in two axial directions, and a head device having an extremely simple structure can be realized. Further, the flexible printed wiring board is formed by curving a conductor such as a copper foil formed of a uniform material as a spring material, and is configured such that the same member is displaced in both biaxial directions. The resonance frequency becomes constant as a whole, and it is possible to prevent the occurrence of partial harmful resonance.

[0028]

As described above, according to the present invention, it is possible to provide a head device having a simple structure, excellent assembling workability, and vibration characteristics effective for servo control, and a variable support substrate thereof.

[Brief description of drawings]

FIG. 1 is a diagram showing an appearance of an embodiment of the present invention.

FIG. 2 is an exploded perspective view of an embodiment of the present invention.

FIG. 3 is an operation explanatory view of the device of the present invention.

FIG. 4 is a structural explanatory view of a flexible printed wiring board according to an embodiment of the present invention.

FIG. 5 is a diagram showing another embodiment of the present invention.

[Explanation of symbols]

5A, 5B ... Flexible printed circuit board, 6 ... Objective lens, 7 ... Integrated optical head section, 8 ... Focus coil, 9 ... Tracking coil, 10 ... Magnet, 11
... electromagnetic yoke, 12 ... guide plate, 13 ... press plate, 14 ...
Fixing screws.

Claims (8)

[Claims] 1. A head portion, one end side of which is supported, the middle portion of which is curved and the other end side of which is attached to a fixed portion, which elastically floats and holds the head portion, and A supporting means by a flexible printed wiring board integrally having wiring for obtaining electrical connection to the head portion from a fixed portion side; a mover provided in the head portion; A head device comprising: a stator for applying a magnetic field to control the position of the head unit. 2. The head portion has at least an objective lens, a semiconductor laser element, a collimator lens, and a photodetector inside a frame, and a side surface of the head portion includes:
An integrated optical head unit having a focus coil and a tracking coil as the mover, wherein the support means attaches one end sides of the two flexible printed wiring boards to the left and right ends of the integrated optical head unit, respectively. The head drive device according to claim 1, wherein 3. The wiring of one of the two flexible printed wiring boards is used for guiding a signal from the photodetector of the optical head section to the fixed section side, and the wiring of the other board is the same. The head device according to claim 2, wherein the head device is used for supplying a drive current from the fixed side to the semiconductor laser element and the focus coil and tracking coil of the optical head unit. 4. The wiring of one of the two flexible printed wiring boards is for driving current of the focus coil and the tracking coil, and the wiring of the other substrate is a semiconductor laser of the optical head section. 3. The head device according to claim 2, wherein the head device is used as a drive current for an element and a signal from the photodetector. 5. The head device according to claim 3, wherein the structures of the two flexible printed wiring boards are exactly the same. 6. A member of the frame of the head portion is an engineering plastic material having high rigidity and a low linear expansion coefficient, and one end of the flexible printed wiring board is integrally molded and fixed to the frame by injection molding. The head device according to claim 1, wherein: 7. The fixing portion is made of an engineering plastic material having a high rigidity and a low linear expansion coefficient, and the other end of the flexible printed wiring board is integrally fixed to the fixing portion by injection molding. The head device according to claim 1, wherein: 8. A wiring pattern of a conductor such as a copper foil is formed on at least one side surface of a flexible rectangular film base, and the conductor is a spring material, and the thickness direction and the radial direction coincide with each other. The curved state of the semicircular shape is a steady shape, and biaxial directions of a direction connecting the both ends of the semicircular shape and a direction connecting the center of the semicircular shape and the center of the circumference of the semicircular shape. A head support substrate that is displaceable, has a head portion that is driven by an electromagnetic mover at one end, and is fixed to a fixed portion at the other end.