JP3489115B2 - Pickup head - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a CD, an LD, and a D.
The present invention relates to a pickup head applied to an optical disk device that reproduces data recorded on an optical disk such as a VD or MD and records data.

[0002]

2. Description of the Related Art Conventionally, CD (compact disc), L
Practical use of an optical disk device capable of reading (reproducing) data recorded on an optical disk such as D (laser disk), DVD (digital versatile disk), MD (mini disk) and writing (recording) data on the optical disk. Has been done. The optical disk device is provided with a pickup head that irradiates the optical disk with a light beam and detects the reflected light as a configuration for performing the above-described reproduction and recording.

The optical disk has tracks formed on the recording surface in a concentric or spiral shape. The data is recorded on this track. A mirror portion of the total reflection area is formed between the tracks.

The pickup head detects a light projecting unit that irradiates the optical disc with a light beam, an objective lens (hereinafter simply referred to as a lens) that narrows the light beam emitted from the light projecting unit, and a reflected light from the optical disc. It has a light receiving part. The pickup head is provided with a mechanism unit that vertically displaces the lens so that a track formed on the optical disk can be focused. This mechanism is called a focus mechanism. Further, a mechanism portion for horizontally displacing the lens is provided so that the light beam can be irradiated to the center of the track. This mechanism section is called a tracking mechanism.

FIG. 3 is a diagram showing the structure of a conventional pickup head. The pickup head 20 is the lens 2
It has a lens holder 21 for holding 2 and a base 25 for mounting the lens holder 21. A shaft 26 is formed on the base 25. On the other hand, the lens holder 21
An opening is formed in the vertical direction so as to penetrate therethrough. The lens holder 21 is attached to the base 25 by passing the shaft 26 of the base 25 through the opening. The lens holder 21 attached to the base 25 is vertically displaceable along a shaft 26 and rotatable about the shaft 26. The lens holder 21 is provided with a plurality of drive coils 23. Reference numeral 24 is a flexible printed circuit board for supplying a drive current to the drive coil 23.

The drive coil 23 provided in the lens holder 21 is a focus drive coil for displacing the lens holder 21 in the vertical direction along the shaft 26, and the lens holder 21 is rotated about the shaft 26. It is a coil for tracking drive for making it.

The pickup head 20 supplies the drive current to the focus drive coil via the flexible printed circuit board 24, and the magnetic field generated by the drive current causes the lens holder 2 to move.
1 is displaced vertically along the axis 26. Focusing on an optical disk (not shown) can be performed by adjusting the amount of vertical displacement of the lens holder 21. The amount of vertical displacement of the lens holder 21 can be adjusted by the magnitude of the current supplied to the focus driving coil via the flexible printed board 24.

Further, the pickup head 20 rotates the lens holder 21 about the shaft 26 by a magnetic field generated by supplying a driving current to the tracking driving coil via the flexible printed board 24. Lens holder 2
By adjusting the rotation amount of 1, the irradiation position of the light beam on the optical disk, that is, the center of the lens 22 can be aligned with the center of the track (track for reading or writing data) of the optical disk. Lens holder 2
The rotation amount of 5 can be adjusted by the magnitude of the current supplied to the tracking drive coil via the flexible printed board 24.

Further, a pickup head (actually No. 1-154522) in which a drive coil is formed by a conductive foil on a flexible printed circuit board, or a pickup head which supplies a drive current to the drive coil by the conductive foil on the flexible printed circuit board. (Actual Kaihei 1-109823
No.) is proposed.

[0010]

By the way, in the conventional pickup head 20 described above, one end of the flexible printed board 24 is attached to the lens holder 21 as shown in FIG.
The side surface of the lens 22 facing the holding portion (hereinafter, referred to as the rear end surface) was attached with an adhesive. The other end of the flexible printed board 24 is connected to a drive circuit (not shown) that supplies a drive current to the focus drive coil and the tracking drive coil.
A drive circuit (not shown) is fixed to the main body of the device.

The lens holder 21 was pulled obliquely downward by the flexible printed circuit board 24 attached to the rear end surface. The rear end surface and the shaft 26 are relatively distant from each other, and the lens holder 21 is configured to be vertically displaceable along the shaft 26 and rotatable about the shaft 26 as described above. . Therefore, the lens holder 2
In No. 1, the holding portion side of the lens 22 is raised, and the rear end face side which is pulled obliquely downward by the flexible printed circuit board 24 is lowered, and it is easy to be in a tilted state, and it is difficult to keep the lens 22 horizontal with respect to the optical disc. there were.
If the lens 22 is not horizontal with respect to the optical disk, the irradiation position of the light beam on the optical disk will not be stable, and the reliability of the apparatus body will be reduced.

As one method for solving the above problem, it has been proposed that the flexible substrate be loosened and adhered to the lens holder 21 (JP-A-9-288834).
issue). In this technique, it is proposed that a hollow concave portion is formed on the bottom surface of the lens holder 21, and the flexible printed circuit board 24 is curved in a U shape in the concave portion so as to be loosened.

However, the above-mentioned technique is not compatible with the lens holder 2
Since the hollow concave portion must be formed on the bottom surface of the lens holder 1, the processing of the lens holder 21 becomes complicated, and the processing cost increases, which causes a problem of cost increase.

Further, at the time of assembly, the flexible printed circuit board 24 must be placed (bonded) in the concave portion of the lens holder 21 with a slack in a U shape. Here, if the hollow portion of the concave portion is made large, the size of the apparatus main body becomes large, which is not preferable. On the other hand, if the hollow portion is made smaller, there is a problem that the assembly work for disposing the flexible printed circuit board in the hollow portion in a U-shape with a slack is troublesome and the number of assembling steps is increased.

An object of the present invention is to improve the reliability of the apparatus main body by suppressing the inclination of the lens holder and stabilizing the irradiation position of the light beam on the optical disc.
An object of the present invention is to provide a pickup head that does not increase the size of the apparatus body, increase the cost, and increase the number of assembling steps.

[0016]

The pickup head of the present invention has the following constitution in order to solve the above-mentioned problems.

(1) A lens holder having a flat bottom surface for holding a lens, a base on which the lens holder is vertically displaceable along an axis, and a lens holder attached to a driving coil provided on the lens holder. A pickup head, comprising: a flexible printed circuit board that supplies a mutation current for vertically mutating the lens.
The holder is located on the bottom surface near the shaft and above the lens.
With a plate-shaped protrusion on the side facing the holder
Is Jo, the flexible printed circuit board, affixed one end portion to the vicinity of the plate-like projections on the bottom surface from <br/> side opposite to the holding portion of the lens of the lens holder, the plate-like Was bent in the vicinity of the projecting portion and was pulled out to the side surface side facing the holding portion of the lens to which the end portion was attached.

[0018]

( 2 ) The lens holder is attached so as to be rotatable about the shaft. ( 3 ) The flexible printed board was attached to the lens holder with an ultraviolet adhesive.

In the above arrangement, the flexible printed circuit board for supplying the driving coil provided in the lens holder with the mutating current for mutating the lens holder in the vertical direction is provided from the side surface facing the lens holding portion of the lens holder. A plate-like protrusion provided on the bottom surface near the side shaft
Of the flexible printed circuit board, and the end portion of the flexible printed circuit board was pulled out to the side surface side to which the flexible printed circuit board was bonded. Therefore, the flexible printed circuit board is pulled substantially downward (axial direction) near the axis. Therefore, most of the force applied to the lens holder by the flexible printed circuit board is a force in the direction of pulling the lens holder in the axial direction.

As described above, since the lens holder cannot be pulled obliquely downward as in the conventional case, the holding portion side of the lens is raised and the rear end surface side (side to which the flexible printed board is attached) is lowered and tilted. Hateful. Therefore, the horizontality of the lens can be maintained. Therefore, the irradiation position of the light beam on the optical disk is stabilized, and the reliability of the apparatus main body can be improved.

Further, since the lens holder does not require a hollow concave portion on the bottom surface, the processing cost of the lens holder can be suppressed and the work for attaching the flexible printed circuit board to the bottom surface of the lens holder can be easily performed. There is no increase in man-hours.

Further, when the lens holder is rotated along the axis in the vertical direction or about the axis, the projection is provided between the shaft and the end of the flexible printed board to which the flexible printed board is attached. Since the printed circuit board and the shaft do not rub against each other, disconnection of the flexible printed circuit board can be prevented.

Furthermore, since the flexible printed circuit board is adhered to the lens holder with an ultraviolet ray adhesive (UV adhesive), the stability over time is good (hard to peel off), and the reliability of the apparatus body can be further improved.

[0025]

DETAILED DESCRIPTION OF THE INVENTION A pickup head according to an embodiment of the present invention will be described below. Figure 1 (A)
FIG. 1 is a diagram showing a pickup head that is an embodiment of the present invention, and FIG. 1 (B) is a plan view in the AA direction shown in FIG. 1 (A). 2A is a diagram showing a lens holder applied to the pickup head of this embodiment, and FIG. 2B is a plan view of this lens holder.

The pickup head 1 of this embodiment is
CD (Compact Disc), LD (Laser Disc), DVD (Digital Versatile Disc), M
It is applied to an optical disk device that reads (reproduces) data recorded on an optical disk such as a D (mini disk) and writes (records) data on the optical disk.

The pickup head 1 includes a lens holder 2
And a base 11. The lens holder 2 holds an objective lens 3 (hereinafter, simply referred to as a lens) at its tip. The lens holder 2 is formed with an opening 4 penetrating in the up-down direction at substantially the center thereof.

A plurality of driving coils 5 are formed on the side surface. The drive coil 5 includes a focus drive coil for vertically displacing the lens holder 2 along the shaft 12 and a tracking drive coil for rotating the lens holder 2 about the shaft 12. .

A flexible printed circuit board 6 for electrically connecting a drive circuit (not shown) to the drive coil 5 and supplying a drive current to the drive coil 5 is attached to the lens holder 2. . The flexible printed circuit board 6 extends from the side surface (hereinafter, referred to as a rear end surface) facing the holding portion holding the lens 3 to the vicinity of the opening 4 on the bottom surface of the lens holder 2 (up to immediately before the protrusion 7 shown below). ) It is pasted. The bottom portion of the lens holder 2 to which the flexible printed circuit board 6 is attached is a flat surface as shown in the figure.

Further, the lens holder 2 is provided with a protrusion 7 near the opening 4 on the bottom surface and on the rear end face side.
The flexible printed circuit board 6 described above is used for the lens holder 2
It is pasted up to just before the protrusion 7 on the bottom surface of the. That is, the flexible printed circuit board 6 is the lens holder 2
To the vicinity of the shaft 12 which will be described later on the bottom surface (see FIG. 2B).
The point a) is attached. The flexible printed circuit board 6 is curved so as to come into contact with the protruding portion 7, and is drawn out to the rear end face side. The flexible printed circuit board 6 is not attached to the protrusion 7. The adhesive is applied to the portion shown by hatching in FIG. The adhesive used for sticking the flexible printed circuit board 6 to the lens holder 2 is not particularly limited, but an ultraviolet adhesive (UV adhesive) whose change with time is small is preferable.

The adhesive may be applied to the entire contact surface between the flexible printed circuit board 6 and the bottom surface of the lens holder 2.

As described above, since the rear end surface and the bottom surface of the lens holder 2 on which the flexible printed circuit board 6 is adhered are flat, the flexible printed circuit board 6 can be easily adhered. Further, the lens holder 2 has a simple shape as described above, and the cost required for processing can be sufficiently suppressed.

The lens holder 2 is attached to the opening 4 through a shaft 12 provided in the center of the base 11 (see FIG. 1). The lens holder 2 is displaceable in the vertical direction along the shaft 12 and rotatable about the shaft 12. Further, as described above, the flexible printed circuit board 6 is attached to the bottom surface of the lens holder 2 up to the vicinity of the shaft 12, curved so as to come into contact with the protruding portion 7 and drawn out to the rear end face side. It is pulled out (extended) almost right below (axial direction).

The driving force for displacing the lens holder 2 in the vertical direction along the shaft 12 and the driving force for rotating the lens holder 2 about the shaft 12 are the driving coil 5 (focus driving coil and tracking driving coil). ) Is obtained from the magnetic field generated when a drive current is supplied to The magnitude of the magnetic field is
It can be adjusted by the magnitude of the current supplied to the driving coil 5.
The drive coil 5 includes a focus drive coil and a tracking drive coil.

Further, in this figure, the light projecting portion for irradiating the laser beam and the light receiving portion for detecting the reflected light from the optical disk are not shown. The light projecting unit and the light receiving unit are arranged below the lens 3.

Next, the operation of the pickup head 1 of this embodiment will be described.

When the drive current is supplied to the drive coil 5 (focus drive coil) for displacing the lens holder 2 in the vertical direction along the axis 12, the pickup head 1 is generated by the supply of the drive current. The lens holder 2 is vertically displaced along the axis 12 according to the magnitude of the magnetic field. That is, by adjusting the magnitude of the drive current supplied to the drive coil 5, the amount of vertical displacement of the lens holder 2 can be adjusted. The drive current is supplied to the drive coil 5 via the flexible printed board 6.

The flexible printed circuit board 6 is attached from the rear end surface to the bottom surface of the lens holder 2 as described above. The sticking end of the flexible printed circuit board 6 on the bottom surface of the lens holder 2 is immediately before the protruding portion 7 formed on the bottom surface of the lens holder 2. That is,
On the bottom surface of the lens holder 2, the flexible printed circuit board 6 is attached up to the vicinity of the shaft 12. Then, the flexible printed circuit board 6 is curved so as to be in contact with the protruding portion 7, and the end portion of the flexible printed circuit board 6 is pulled out to the rear end face side to which it is attached. Therefore, the flexible printed circuit board 6 is pulled out substantially right below (axial direction) in the vicinity of the shaft 12.

Therefore, when the lens holder 2 is pulled by the flexible printed board 6, the lens holder 2 is pulled in the axial direction (substantially right below) in the vicinity of the shaft 12. Therefore,
The moment acting on the lens holder 2 is suppressed. Thereby, the horizontality of the lens holder 2 can be maintained,
As a result, the horizontality of the lens 3 can be maintained. Therefore, the irradiation position of the light beam on the optical disk can be stabilized, and the reliability of the apparatus main body can be improved.

Further, the protrusion 7 is the opening 4 through which the shaft 12 passes.
Is formed in the vicinity of and on the rear side, and is located between the shaft 12 and the flexible printed circuit board 6. Therefore, it is possible to prevent the shaft 12 and the flexible printed circuit board 6 from rubbing against each other when the lens holder 2 is displaced in the vertical direction along the shaft 12 or when the lens holder 2 is rotated about the shaft 12 described later. Therefore, the breakage of the flexible printed circuit board 6 is suppressed, and the reliability of the apparatus main body can be further improved.

Further, in the pickup head 1 according to this embodiment, the lens holder 2 is rotated around the shaft 12 as described above. The lens 3 is displaced in the horizontal direction with this rotation.

In the pickup head 1, when a drive current is supplied to the drive coil 5 (tracking drive coil) for rotating the lens holder 2 about the shaft 12,
Depending on the magnitude of the magnetic field generated by the supply of the drive current,
The lens holder 2 rotates about the shaft 12. Lens 3
Is displaced in the horizontal direction with this rotation. Therefore, the amount of horizontal displacement of the lens holder 2 can be adjusted by adjusting the magnitude of the drive current supplied to the drive coil 5 (tracking drive coil). The drive current is supplied via the flexible printed board 6.

The mechanism for displacing the lens 3 in the vertical direction along the axis 12 is the focus mechanism.
The tracking mechanism is a mechanism that rotates the shaft about the shaft 12. The focus mechanism is a mechanism unit for focusing on the track of the optical disc set in the main body,
The tracking mechanism is a mechanism for irradiating the center of the track of the optical disc set in the main body with a light beam.

[0044]

As described above, according to the present invention, since the horizontality of the lens can be maintained, the irradiation position of the light beam on the optical disk is stabilized, and the reliability of the apparatus main body can be improved.

Further, it is possible to suppress an increase in the processing cost of the lens holder and to easily attach the flexible printed board to the bottom surface of the lens holder (the increase in the number of assembling steps can be suppressed).

Further, since the breakage of the flexible printed circuit board is prevented, the reliability of the main body of the apparatus can be further improved.

Further, the reliability of the apparatus main body can be improved by using an ultraviolet adhesive having good stability over time for sticking the flexible printed circuit board.

[Brief description of drawings]

FIG. 1 is a diagram showing a pickup head according to an embodiment of the present invention.

FIG. 2 is a diagram showing a lens holder applied to the pickup head of this embodiment.

FIG. 3 is a diagram showing a conventional pickup head.

[Explanation of symbols]

1-Pickup Head 2-Lens Holder 3-Objective Lens (Lens) 4-Aperture 5-Drive Coil (Focus Drive Coil, Tracking Drive Coil) 6-Flexible Printed Circuit Board 7-Protrusion 11-Base 12- axis

Claims (4)

(57) [Claims] 1. A lens holder having a flat bottom surface for holding a lens, the lens holder being vertically displaceable along an axis,
A pickup head including a base mounted so as to be rotatable about the axis, and a flexible printed circuit board for supplying a displacement current to the lens driving coil provided in the lens holder to vertically displace the lens holder.
In, the lens holder is in the vicinity of the shaft at the bottom,且
A plate-shaped protrusion on the side facing the holding part of the lens
A shape having said flexible printed circuit board, affixed one end with UV adhesive to the vicinity of the plate-like projection at the bottom surface from the side opposite to the holding portion of the lens of the lens holder, the A pickup head which is curved near a plate-like protrusion and is drawn out to the side surface side facing the holding portion of the lens to which the end portion is attached. 2. A lens holder having a flat bottom surface for holding the lens, a base on which the lens holder is vertically displaceable along an axis, and a lens holder mounted on the lens holder so as to move the lens holder up and down. A pickup head including a flexible printed circuit board that supplies a variation current for changing the direction.
In, the lens holder is in the vicinity of the shaft at the bottom,且
A plate-shaped protrusion on the side facing the holding part of the lens
A shape having said flexible printed circuit board, affixed one end portion to the vicinity of the plate-like projections in the bottom from the side opposite to the holding portion of the lens of the lens holder, the
The end portion was attached by bending it near the plate-shaped protrusion .
A pickup head pulled out to the side surface facing the holding portion of the lens . 3. The pickup head according to claim 2 , wherein the lens holder is attached so as to be rotatable around the shaft. 4. A pick-up head according to claim 2 or 3 the flexible printed circuit board was attached to the lens holder with an ultraviolet adhesive.