JPH10124901A - Optical pickup device and adjusting method of its radial dynamic skew - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical pickup device having a low radial dynamic skew with a small number of parts and extremely simple work. SOLUTION: A magnetic flux density distribution F of a magnetic circuit composed of a yoke part 701 equipped with one pair of leg parts 701A and 701B having a U-shaped cross section and constituting a biaxial actuator and a magnet M disposed in an inner surface of at least one leg part 701A of this yolk part 701 and generating lines of magnetic force between the two leg parts is adjusted by bridging the two leg parts of the yoke part 701 with a small piece of a magnetic member 710, so as to reduce the radial dynamic skew.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical pickup device for recording information on an optical disk or reading information recorded on the optical disk, and more particularly, to a magnetic circuit of a two-axis actuator incorporated in the optical pickup device. It concerns the device.

[0002]

2. Description of the Related Art First, a conventional optical pickup device will be described with reference to FIGS. FIG. 3 is a perspective view of a conventional optical pickup device, FIG. 4 is a perspective view showing a yoke portion of the optical pickup device shown in FIG. 3, and FIG. 5 is formed by the yoke portion shown in FIG. FIG. 6 is a side view of the yoke for explaining the magnetic circuit, and FIG. 6 is a side view of the yoke showing one state of a magnetic flux density distribution generated by the magnetic circuit of FIG.

In FIG. 3, reference numeral 1 generally indicates an optical pickup device of the prior art. The optical pickup device 1 includes a pickup main body 2 and a fixed support 6. Further, the pickup main body 2 has a movable portion 3.
The movable section 3 is horizontally and horizontally focused by four feeding and supporting wires (hereinafter simply referred to as “supporting wires”) 5 in a focusing direction (recording surface of the optical disc). Are supported by the fixed part 4 so as to be swingable in a direction perpendicular to the optical disk and in a tracking direction (a radial direction of the optical disk or a direction crossing a recording track on the optical disk).

The movable part 3 has an objective lens 3 at its tip.
01 is a flat bobbin 302 which supports the objective lens 3 and is wound around a coil bobbin 303 at the rear thereof.
01 and an objective lens 301 for driving the optical disc 01 in a direction perpendicular to the recording surface of an optical disc (not shown).
And a pair of tracking coils 305 for driving the optical disk in the radial direction of the optical disk are fixed.

The fixing portion 4 also serves as a terminal plate, and is embedded in a state that two terminals 402 are provided on the left and right sides, and a total of four terminals 401 and two terminals 402 are provided on both left and right side surfaces, respectively. The resin is molded in a rectangular parallelepiped shape. A flexible wire Fw is soldered to the terminal 401 and connected thereto. Also, the two left and right terminals 402
Are connected to the support wire 5, respectively, and the focusing coil 304 and the tracking coil 305 are connected to each other.
Is configured to be able to supply a current.

The fixed support 6 comprises a yoke base 7 and an adjusting plate 8. As shown in FIG. 4, the yoke base 7 is formed of a single U-shaped metal plate, and a portion where the movable portion 3 is set has a pair of upwardly cut and raised portions. Legs 701A, 701
A U-shaped yoke portion 701 is formed in B, and a magnetic circuit is formed by mounting a magnet M on the inner surface of one or both of the leg portions 701A and 701B. The yoke portion 701 in the illustrated example has the magnet M
The yoke part mounted only on the 01A side is shown. In the following description, a description will be given using the yoke portion on which the single magnet M is mounted. On the other hand, support legs 7 are respectively provided at the inner edges of the U-shaped open ends where the fixing portions 4 are set.
02 is formed so as to be vertically cut and raised upward.

The adjusting plate 8 is a small piece of approximately quadrilateral having an area that can be accommodated in the U-shape of the yoke base 7, and the front portion thereof has a portion 80 on which the fixing portion 4 is mounted.
1 and supporting legs 8 on both sides of the rear end.
02 is formed so as to be vertically cut and raised upward.

The fixed portion 4 of the pickup body 2 is vertically fixed to the front fixed portion 801 of the adjustment plate 8. In this fixing, the two legs 701A and 701B of the yoke 701 of the yoke base 7 are mounted so as to sandwich the focusing coil 304 and the tracking coil 305 formed in the movable portion 3. Thus, a two-axis actuator is configured. With this fixing, the entire pickup main body 2 is supported by the adjustment plate 8.

Next, the adjustment plate 8 supporting the pickup main body 2 is brought into the inside of the U-shaped yoke of the yoke base 7, and its support legs 802 are aligned with the support legs 702 of the yoke base 7. The adjustment plate 8 is finely adjusted in the up, down, left, right, front and rear directions in the vicinity of the two support legs 702, 802, so that the objective lens 301 of the pickup body 2 is held at a predetermined position.
802 is soldered with solder Sb, and the adjustment plate 6 is fixed to the yoke base 7 in this way, and the assembly of the optical pickup device 1 is completed.

[0010]

However, a magnetic flux is generated in the magnetic circuit formed by the yoke portion 701 of the conventional optical pickup device 1 having such a structure, and the magnetic flux density distribution F is shown in FIG. As shown in FIG.

If the magnetic flux density distribution F is vertically symmetrically distributed and the movable section 3 including the objective lens 301 is also mechanically adjusted to the horizontal state normally and supported, the optical pickup device 1 At the time of tracking drive, the movable section 3 moves to a predetermined track position while maintaining the horizontal state, and can perform good reading (reproduction) of a signal.

However, if the magnetic flux density distribution F is biased as described above, even if the movable part 3 is mechanically normally adjusted to a horizontal state and supported, the movable part 3
At the time of tracking driving, the objective lens 301 is tilted to the left or right, and the performance of signal reading by a light beam is degraded. The inclination of the objective lens 301 with respect to the horizontal plane is usually a very small angle of about 0.1 °, and there is no problem in reproducing CDs currently on the market. As described above, strict precision is required. For example, in the case of reproducing a DVD, which is currently a topic, if an inclination of 0.1 ° or more occurs, the jitter value of the reproduced video signal becomes poor, and the image quality of the reproduced video deteriorates.
In addition, even when the recording / reproducing apparatus of the optical disk is used as a peripheral device of a computer, if the above-mentioned jitter occurs, an error occurs and an undesirable phenomenon occurs. The tilt change (skew) when the objective lens is moved in the radial direction during tracking is hereinafter referred to as “radial dynamic skew”.

An object of the present invention is to provide a method of adjusting an optical pickup apparatus and an optical pickup apparatus for reducing the radial dynamic skew with a small number of parts and a very simple operation. It is the purpose.

[0014]

SUMMARY OF THE INVENTION Therefore, a method for adjusting a radial dynamic skew of an optical pickup device according to the present invention uses an optical disk for recording information on an optical disk or reading information recorded on the optical disk. A yoke section having a pair of U-shaped legs for driving an objective lens for irradiating a beam in a direction perpendicular to the recording surface of the optical disc and in a radial direction of the optical disc, and the yoke section thereof In an optical pickup device having a magnetic circuit composed of a magnet disposed on at least one leg inner surface and generating a magnetic field line between both legs, a thickness, a shape, or a magnetic characteristic that is prepared in advance differs. The magnet is generated in the yoke portion by the magnet using at least one magnetic member among a plurality of small magnetic members. It adopts a method of adjusting the flux density distribution, and solve the above problems.

Further, the optical pickup device of the present invention comprises:
In order to record information on the optical disk or read information recorded on the optical disk, an objective lens for irradiating the optical disk with a light beam is driven in a direction perpendicular to a recording surface of the optical disk and in a radial direction of the optical disk. In the optical pickup device having a magnetic circuit for performing the operation, the magnetic circuit is disposed on a yoke portion having a pair of legs having a U-shaped cross section and at least one leg inside the yoke portion. And a magnet that generates magnetic lines of force, and bridges a small piece of magnetic member to both legs of the yoke to adjust the magnetic flux density distribution of the yoke, thereby solving the problem.

Therefore, according to the method of adjusting the radial dynamic skew of the optical pickup device of the present invention, the magnetic flux density distribution of the magnetic circuit of the optical pickup device can be easily adjusted only by selecting the small magnetic member. . Further, the optical pickup device of the present invention can reduce the occurrence of radial dynamic skew with an extremely simple structure without substantially modifying the structure of the conventional optical pickup device.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of an optical pickup device and a method for adjusting a radial dynamic skew thereof according to the present invention will be described with reference to FIGS. FIG. 1 shows a yoke portion forming a magnetic circuit and a first adjusting magnetic member having a certain thickness in the optical pickup device of the present invention. FIG. 1A is a side view, and FIG. FIG. 9C is a schematic diagram showing the state of occurrence of the magnetic flux density distribution of the yoke portion shown in FIG. 10A, and FIG.
FIG. 2 is a schematic view showing another magnetic flux density distribution generated in the yoke portion when the adjustment magnetic member is used. FIG. 2 shows various shapes of the adjustment magnetic member, and FIG. FIG. 4B is a plan view showing a third adjusting magnetic member having a shape, FIG. 3B is a schematic diagram showing a state of generation of a magnetic flux density distribution in a yoke portion when the adjusting magnetic member of FIG. 2A is used, and FIG. FIG. D is a plan view showing the H-shaped fourth adjusting magnetic member of FIG.
FIG. 8E is a schematic view showing the state of generation of the magnetic flux density distribution in the yoke portion when the adjustment magnetic member is used, FIG. E is a plan view of a fifth adjustment magnetic member with caulking projections, and FIG. It is a top view which shows the 6th magnetic member for an adjustment with the crimped protrusion of a shape. The same components as those of the optical pickup device 1 according to the related art will be described with the same reference numerals.

In FIG. 1, reference numeral 710 denotes a first adjusting magnetic member. The adjusting magnetic member 710 is a rectangle having a thickness T, and has both legs 701A and 701A of the yoke 701.
It is strung over 01B. This state is referred to as "bridge" in the following description. Leg 701
Magnetic flux Mf from magnet M fixed to the inner surface of A
Part flows from the leg 701B through the connecting portion 701C through the magnetic circuit composed of the leg 701A and the magnet M,
The remaining magnetic flux Mf from the magnet M flows from the leg 701B through the adjusting magnetic member 710 to the magnetic circuit composed of the leg 701A and the magnet M. That is, the presence of the latter magnetic circuit reduces the magnetic resistance.

The yoke portion 701 is provided with the adjusting magnetic member 71.
In the case where the magnetic flux density distribution F as shown in FIG. 6 is generated with the center deviated downward when the bridge is not bridged at 0, the yoke portion 701 is adjusted by the adjusting magnetic member 710 as described above. By bridging, the symbol Fa in FIG.
As shown by, a magnetic flux density distribution nearly vertically symmetric can be formed, and the center of the magnetic flux density distribution also rises from below the magnet M to the center.

The bias of the magnetic flux density distribution F of the yoke 701 can be adjusted by changing the thickness of the adjusting magnetic member 710 according to the degree of the bias of the objective lens 301. The second adjustment magnetic member 720 shown in FIG. 1D is a case where the magnetic flux density distribution Fb is adjusted using a thin plate, and the center does not reach the center of the magnet M.

Although not shown, the adjusting magnetic member is formed by a thick plate, and the leg 7 of the yoke 701 is
By bridging 01A and 701B, the center of the magnetic flux density distribution F can be distributed above the center of the magnet M. As described above, the amount of movement of the center of the magnetic flux density distribution F can be controlled by changing the thickness of the adjusting magnetic member.

In addition to changing the thickness of the adjusting magnetic member, as shown in FIG. 2, the shape of the adjusting magnetic member may be devised so that a plurality of types of adjusting magnetic members are prepared in advance and provided for adjustment. Can be. The third adjusting magnetic member 730 shown in FIG. 2A is formed in an H shape. As shown in FIG. 2B, when the two legs 701A and 701B of the yoke 701 are bridged by the adjusting magnetic member 730, the magnetic flux Mf from the magnet M is formed into a magnetic flux density distribution as shown by a symbol Fc, for example. be able to.

FIG. 2C shows a fourth adjusting magnetic member 740. This adjusting magnetic member 740 is similar to the third adjusting magnetic member 730, except that the width of the center plate of the H-shape is slightly wider and the magnetic resistance is lower than that of the third adjusting magnetic member 730. It was done. Accordingly, as shown in FIG. 2D, when the two legs 701A and 701B of the yoke 701 are bridged by the adjusting magnetic member 740, the magnet M
Can be formed into a magnetic flux density distribution as indicated by reference numeral Fd, for example, and the center can be moved slightly above the center of the magnetic flux density distribution Fc shown in FIG. 2B.

The fifth adjusting magnetic member 75 shown in FIG. 2E
Numeral 0 indicates that a caulking projection 711 is formed at each corner of the rectangular adjustment magnetic member 710 shown in FIG. These caulking projections 711 are attached to the legs 701 of the yoke 701.
A, 701B, and these caulking projections 711
Are bent toward each other of the pair of caulking projections 711, that is, caulked and fixed. When the adjusting magnetic member 750 having such a shape is used, a concave portion is fitted in a corner on the outer side of the upper end of both legs 701A and 701B of the yoke 701.

The sixth adjusting magnetic member 76 shown in FIG. 2F
Numeral 0 indicates that the protrusion 711 is formed at each corner of the H-shaped adjusting magnetic member 730 shown in FIG.
This adjusting magnetic member 760 is also the fifth adjusting magnetic member 75.
It can be swaged in the same manner as 0 and squeezed into the yoke 701.

After adjusting the magnetic flux density distribution F of the magnetic flux Mf from the magnet M, the adjusting magnetic member is connected to the yoke 70.
1 and fixed to both legs 701A, 701B.
The fixing method may be caulked as described above,
You may bond with an adhesive. Also, both legs 701A, 70
You may take the fixing method of locking to 1B.

In the above embodiment, a plurality of adjusting magnetic members are prepared in advance with different thicknesses and shapes, and the radial dynamic skew is reduced most while measuring the inclination of the objective lens 301 using a measuring instrument. In order to reduce the radial dynamic skew to an allowable range, the magnetic members for adjustment are replaced and mounted on the legs 701A and 701B of the yoke 701, and after the adjustment is completed, the radial dynamic skew is adjusted. The adjusting magnetic member that minimizes the skew is attached to the legs 701A and 701A.
Fixed to 01B. In this way, it is possible to obtain an optical pickup device that is adjusted very well.

In the above embodiment, a plurality of adjusting magnetic members having different thicknesses and shapes were prepared in advance. These adjustment magnetic members are iron, and the description has been made on the assumption that the magnetic characteristics are the same as the magnetic characteristics of iron, which is a member of the yoke portion 701. It is needless to say that a plurality of adjusting magnetic members different from each other may be prepared.

[0029]

As described above, according to the method for adjusting the radial dynamic skew of the optical pickup device of the present invention, a complicated adjusting mechanism or a fixing mechanism is not required, and only the magnetic member of a small piece is selected. The magnetic flux density distribution of the magnetic circuit of the optical pickup device can be adjusted very easily. Further, the optical pickup device of the present invention does not need to modify the structure of the two-axis actuator of the optical pickup device of the prior art, and does not need to modify the structure of the yoke part at all. And the occurrence of radial dynamic skew can be reduced with a very simple structure.
It is not necessary to prepare a large number of types of adjustment magnetic members, and the adjustment magnetic members can be prepared at extremely low cost. Furthermore, since the components are inexpensive and the adjustment operation can be performed very easily, a precise optical pickup device can be obtained without increasing the manufacturing cost.

[Brief description of the drawings]

1A and 1B show a yoke portion forming a magnetic circuit and a first adjusting magnetic member having a certain thickness in the optical pickup device of the present invention. FIG. A is a side view, and FIG. FIG. 9C is a schematic diagram showing the state of occurrence of the magnetic flux density distribution of the yoke shown in FIG. 10A, and FIG. 10D is a diagram showing the yoke when the second adjusting magnetic member having another thickness is used. FIG. 8 is a schematic diagram showing a state of occurrence of another magnetic flux density distribution.

FIG. 2 shows various forms of adjusting magnetic members, and FIG. 2A is a plan view showing an H-shaped third adjusting magnetic member;
FIG. B is a schematic diagram showing a state of generation of a magnetic flux density distribution in the yoke portion when the adjustment magnetic member of FIG. A is used, and FIG. C shows a fourth H-shaped fourth adjustment magnetic member. FIG. 9D is a schematic view showing a state in which the magnetic flux density distribution of the yoke portion is generated when the adjustment magnetic member of FIG. 10C is used, and FIG. 10E is a view of a fifth adjustment magnetic member with a caulking projection. FIG. 17F is a plan view, and FIG. 17F is a plan view showing a sixth adjusting magnetic member having an H-shaped caulking projection.

FIG. 3 is an exploded perspective view of a conventional optical pickup device. Conventional technology

FIG. 4 is a perspective view showing a yoke portion of the optical pickup device shown in FIG.

FIG. 5 is a side view of the yoke for explaining a magnetic circuit formed by the yoke shown in FIG. 3;

6 is a side view of a yoke showing one state of a magnetic flux density distribution generated by the magnetic circuit of FIG. 5;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Optical pick-up apparatus, 2 ... Pick-up main body, 3
.. Movable part 301 301 objective lens 304 focusing coil 305 tracking coil 4 fixed part
6: fixed support portion, 7: yoke base, 701: yoke portion, 701A, 701B: legs of yoke portion 701, 70
1C: connecting portion of legs 701A, 701B, 710: first
... The second adjusting magnetic member, 720.
30: third adjusting magnetic member, 740: fourth adjusting magnetic member, 750: fifth adjusting magnetic member, 760: sixth
Adjusting magnetic member, 711...

Claims (2)

[Claims] 1. An object lens for irradiating a light beam on an optical disc for recording information on the optical disc or reading information recorded on the optical disc, the objective lens being arranged in a direction perpendicular to a recording surface of the optical disc and the optical disc. A yoke portion having a pair of legs having a U-shaped cross section for driving in the radial direction of the yoke portion, and a magnet disposed on the inner surface of at least one leg portion of the yoke portion and generating a magnetic force line between the two legs. An optical pickup device having a magnetic circuit composed of: a magnet prepared by using at least one magnetic member among a plurality of small-sized magnetic members having different thicknesses, shapes, or magnetic characteristics prepared in advance. A method for adjusting a radial dynamic skew of an optical pickup device, wherein a distribution of a magnetic flux density generated in the yoke portion is adjusted. 2. An object lens for irradiating a light beam on the optical disc for recording information on the optical disc or reading information recorded on the optical disc, the objective lens being arranged in a direction perpendicular to a recording surface of the optical disc and the optical disc. An optical pickup device having a magnetic circuit for driving in the radial direction of the optical pickup device, wherein the magnetic circuit is disposed on a yoke portion having a pair of legs having a U-shaped cross section and at least one leg inner surface of the yoke portion. And a magnet for generating magnetic lines of force between both legs, wherein a small magnetic member for adjusting the magnetic flux density distribution of the yoke is bridged to both legs of the yoke. Optical pickup device.