JPH05189788A - Objective lens suspension arm - Google Patents

Abstract

PURPOSE:To relieve the effect of a temp. change on a suspension arm and to suppress skew and shifts of the visual field and position of an objective lens. CONSTITUTION:One end of this objective lens suspension arm 40 is fixed on the body of a biaxial actuator and the other end is used to hold an objective lens. Resin hinges 30, 32, 24, 28 are fitted to both the ends and the body 44 of this arm 40 connecting both the ends is made of a metallic sheet.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention drives and displaces an objective lens for focusing a light beam emitted from a light source such as a semiconductor laser on a signal recording surface of an optical disk in a focus direction, a tracking direction, or one of these directions. The present invention relates to a suspension arm of an objective lens to be used.

[0002]

2. Description of the Related Art Conventionally, a means for irradiating a signal beam on a signal recording surface of an optical disk which is mounted on a disk rotation driving device and is rotated to read an information signal recorded on the optical disk or write a predetermined information signal on the optical disk. An optical pickup device is used as this. In this optical pickup device, an objective lens for focusing the light beam emitted from the semiconductor laser on the signal recording surface of the optical disc is driven and displaced in two axial directions, that is, the focus direction and the tracking direction by a magnetic driving force. An objective lens driving device is provided so that the light beam is focused on the signal recording surface of the optical disc to accurately scan the recording track.

In such an objective lens driving device, the objective lens is supported by a suspension arm so as to be movable in two axial directions. For example, when operating an optical pickup device such as a portable CD player in all postures, the tracking balance type suspension arm in which the axes of the objective lens and the laser beam do not change due to the posture difference causes an optical deviation compared to the unbalanced type. There is an advantage that the objective lens and the axis of the laser light do not fluctuate with respect to vibration.

As an example of this tracking balance type suspension arm, conventionally, a suspension arm integrally molded with resin as shown in FIGS. 11 and 12 has been used. The suspension arm generally designated by the reference numeral 21 is molded from a resin material such as polypropylene or polyester elastomer which is resistant to bending fatigue.

A pair of support arms 22 parallel to the upper and lower sides,
One end side (the right side in FIG. 9) of 22 is continuously provided by a continuous portion 23, and the continuous portion of the continuous portion 23 and the support arms 22, 22 has a thin elastic displacement portion 24 in the vertical direction. 24
Is formed. Notch holes 24a, 24a are formed in the central portions of the elastic displacement portions 24, 24 to adjust the elastic displacement force. Further, in front of the connecting portion 23, an attaching portion 25 with the movable body 27 supporting the objective lens 26 shown by a virtual line is integrally formed, and the connecting portion between the connecting portion 23 and the attaching portion 25 is left and right. It is formed in a thin elastic displacement portion 28 in the direction. A cutout hole 28a is also formed in the center of the elastic displacement portion 28 to adjust the elastic displacement force.

On the other hand, the other end side (left side in FIG. 9) of the support arms 22 and 22 is connected by a connecting portion 29, and the connecting portion between the connecting portion 29 and the supporting arms 22 and 22 is vertically moved. The elastic displacement portions 30, 30 are thin in the direction.
Then, cutout holes 30a, 30a are formed in the central portions of these elastic displacement portions 30, 30 to adjust the elastic displacement force. A fixed portion 31 serving as a suspension arm supporting portion is integrally formed behind the continuous portion 29. The connecting portion between the connecting portion 29 and the fixed portion 31 is formed as a thin wall 32 that is thin in the left-right direction.

The suspension arm 21 configured as described above applies a focus coil drive current (not shown) attached to the movable body 27 so that the movable body 27 elastically displaces the support arms 22, 22 to the elastic displacement portions 24, 24. And 3
Focus control can be performed by elastically displacing 0 and 30 and moving the objective lens 26 in the optical axis direction. Further, by applying a drive current to the tracking coil, the movable body 27 elastically displaces the elastic displacement portion 28 to move the objective lens 26 in the direction orthogonal to the optical axis, and tracking control can be performed.

[0008]

However, the above-described resin-integrated mold suspension arm is easily affected by temperature changes, and a typical example thereof is the displacement of the objective lens due to expansion and contraction of the suspension arm. As a result, there is a problem that the optical disc and the optical pickup are tilted, that is, skew is generated, and a visual field of the objective lens with respect to the optical disc signal recording surface is defective.

The present invention has been made to solve the above problems, and an object thereof is to provide a suspension arm for an objective lens in which displacement of the objective lens is less likely to occur due to the influence of temperature change. ..

[0010]

According to the present invention, the above object is made of a non-magnetic thin metal plate material, and the thin metal plate material is bent in parallel so as to face each other from a predetermined connecting portion. An arm member including a first support arm piece and a first support arm piece that is continuously provided in a continuous portion in a direction opposite to the first support arm piece and orthogonal to a surface of the arm piece. This can also be achieved by a suspension arm of the objective lens, which has a mounting portion to be mounted on a fixed support body and a movable body that holds the objective lens by resin molding at the outer ends of the first and second support arm pieces. Then, preferably, the first support arm piece is formed with a plurality of punched holes over the width direction thereof.

In the present invention, the above object is a suspension arm of an objective lens having one end fixed to a biaxial actuator body and the other end holding an objective lens. This is achieved by a suspension arm of an objective lens in which a hinge part made of resin is provided, and an arm body connecting the one end side and the other end side is made of a metal plate.

The arm body is preferably composed of a non-magnetic thin metal plate.

In the suspension arm configured as described above, the resin-molded mounting portion provided on the outer end portion of the first support arm piece is fixed to the suspension fixing base, and the second support arm piece has the same structure. A resin-molded mounting portion provided on the outer end portion is fixed to a movable body supporting the objective lens, and is incorporated into the optical pickup device. And with the suspension arm described above,
With respect to the movement of the objective lens in the focus direction, the pair of first support arm pieces that are parallel to each other bend and deform in the focus direction due to the elastic action of the objective lens itself. The so-called objective lens can be moved in two axial directions, in which the two support arm pieces are elastically deformed and deformed in the tracking direction.

According to the third aspect of the present invention, since the arm body is formed of the metal plate, it is less susceptible to the temperature change, and the suspension is prevented from expanding and contracting in response to the temperature change.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below in detail with reference to the accompanying drawings. It should be noted that the examples described below are suitable specific examples of the present invention, and therefore, various technically preferable limitations are attached thereto, but the scope of the present invention particularly limits the present invention in the following description. Unless otherwise stated, the present invention is not limited to these modes.

FIG. 1 is a perspective view showing a first embodiment of a suspension arm for an objective lens according to the present invention.
The suspension arm indicated by reference numeral 1 is composed of a flexible non-magnetic metal plate arm member 1a and a resin mold portion. The arm member 1a is made of a metal material such as stainless steel, phosphor bronze, or helium copper, or a material thereof. It is made of a composite metal material, and its plate thickness varies slightly depending on the type of metal material, but it is about 40 to 40 μm between 30 and 80μ.
is μ.

The arm member 1a of the suspension arm 1 has a pair of first support arm pieces 3 and 3 which are horizontally bent from the continuous portion 2 so as to face each other upward and downward.
And a second support arm piece 4 extending in a direction opposite to those of the first support arm pieces 3 and 3 and bent up vertically from the continuous portion 2 with respect to the first support arm pieces 3 and 3. ing. Specifically, the first support arm pieces 3 and 3 are made of strip-shaped arm pieces, and the arm pieces 3 and 3 can be flexibly deformed in the plate surface direction. Further, the second support arm piece 4 is formed with a punching hole 5 in the width direction thereof and is provided with elastic displacement portions 6 and 6 having a narrow width on the upper and lower outer edge sides. A bending action of elastically deforming in the surface direction is obtained.

2 and 3 are a plan view and a side view of the suspension arm 1. Hook portions 3a and 3a are formed on the outer end portions of the first support arm pieces 3 and 3, and resin molding is performed on the outer end portions of the first support arm pieces 3 and 3 so that the hook portions 3a and 3a are embedded. A mounting portion 7 formed by molding is provided. A hook portion 4a is also formed on the outer end portion of the second support arm piece 4, and a mounting portion 8 formed by resin molding is provided on the outer end portion of the second support arm piece 4 so that the hook portion 4a is embedded. There is. The continuous portion 2 of the first and second support arm pieces 3 and 4 is reinforced by a reinforcement portion 9 formed by resin molding. As the synthetic resin material used for the above-mentioned mounting portions 7 and 8 and the reinforcing portion 9, for example, polyester resin such as polypropylene resin terephthalate (PBT) having particularly excellent heat resistance is suitable.

FIG. 4 is a plan view showing the suspension arm according to this embodiment incorporated in a biaxial actuator. In this suspension arm 1, an attachment portion 7 formed on the first support arm piece 3 is mold-supported by a fixed support 11 that cantilevers the suspension arm 1, and an attachment portion formed on the second support arm piece 4. 8 is molded and supported by a movable body 13 provided with an objective lens 12. Note that FIG.
In FIG. 14, 14 and 15 are field coils and yokes for driving the biaxial actuator in the focus direction and the tracking direction, 16 is a magnet, and 17 is a fixed substrate on which the biaxial actuator is mounted.

Next, the processing steps of the suspension arm 1 will be described with reference to FIGS. A plate-shaped arm material 1 made of a metal plate punched and stamped (not shown)
0 is the first and second support arm pieces 3, 4 as shown in FIG.
Is in a developed state, and a part of the second support arm piece 4 is formed as cutouts 4b, 4b reaching the central portion of the first support arm piece 3. The arm material 1a molded in this manner is used as the hook portion 3 at the outer end of the first support arm piece 3,3.
a, 3a, hook portion 4a at the outer end of the second support arm piece 4
Bend it at a right angle (Fig. 6). After that, arm material 1
The first support arm pieces 3 and 3 are bent at right angles from the notches 4b and 4b with respect to the continuous connection portion 2 at the center of a so as to face each other in parallel, and the second support arm piece 4 is connected to the continuous connection portion 2 in parallel. Is bent at a right angle in the opposite direction to the first support arm pieces 3 and 3, and the molding of the arm member 1a is completed as shown in FIG. After forming the arm member 1a, the first and second
Molding of the mounting portions 7 and 8 to the support arm pieces 3 and 4 and molding of the reinforcing portion 9 to the continuous portion 2 are performed by a resin molding machine.

In the suspension arm 1 constructed as described above, the resin-molded mounting portion 7 of the first support arm pieces 3, 3 is mold-supported by the fixed support 11 as shown in FIG. The resin-molded mounting portion 8 of the arm piece 4 is mold-supported by the movable body 13 having the objective lens 12 and incorporated in the optical pickup device.

Thus, the suspension arm 1 described above
Then, when the objective lens 12 is driven in the optical axis direction by supplying a predetermined focus current to the focus coil, the first support arm pieces 3 and 3 bend in the focus direction, and the focus operation of the objective lens 12 is performed. Done. Also,
When the objective lens 12 is driven in the direction orthogonal to the optical axis direction by supplying a predetermined tracking current to the tracking coil, the second support arm pieces 3 and 3 move their elastically displaced portions 6 and 6 in the tracking direction. The tracking operation of the objective lens 12 is performed by bending the lens.

The suspension arm constructed as described above and in which the objective lens is moved in the two axial directions has the following advantages as compared with the conventional suspension arm integrally molded with a resin mold.

That is, since the arm member 1a of the suspension arm according to this embodiment is made of a metal plate,
It is not affected by changes in the temperature of the external atmosphere, and therefore the expansion and contraction of the suspension arm due to the changes in temperature does not occur. Problems such as positional deviation can be suppressed to a small level, and an optical pickup device with high accuracy and high reliability can be obtained.

Further, since the arm member 1a is made of a non-magnetic thin metal plate, the magnetic field generated in the focus coil and the tracking coil, the magnet, and the yoke, which are the driving device of the objective lens 12, affects the movement of the arm member 1a. Moreover, the biaxial operation of the objective lens 12 can be accurately performed. In addition, because there is no extremely thin elastic displacement part like the conventional suspension arm integrally molded with resin, there is little variation in accuracy and the suspension arm has a high yield rate with uniform accuracy. It is easy to handle without being deformed even during assembly of the arm. Furthermore, since mounting portions 7 and 8 made of a heat-resistant resin mold are provided on the outer end portions of the first supporting arm pieces 3 and 3 and the second supporting arm piece 4 as arm members, the suspension arm 1 can be mounted on the optical pickup device. Can be easily incorporated, and as a result, in-line automation from molding to processing and assembly of the suspension arm is possible. In addition, the first support arm piece 3,
Since the continuous portion 2 of the third supporting arm piece 4 and the second supporting arm piece 4 is mold-reinforced by the reinforcing portion 9 made of a heat-resistant resin mold, it is possible to prevent metal fatigue which is likely to occur particularly at the bent portion of the arm member 1a. The perpendicularity of the second support arm piece 4 with respect to the first support arm piece 3 can always be set accurately.

FIG. 8 shows a second embodiment of the suspension arm according to the present invention. This is one in which a plurality of punched holes 3b are formed in the first support arm pieces 3 and 3 in the width direction thereof. With this configuration, the first
The spring constant of the support arm pieces 3, 3 can be adjusted. For example, the spring constant can be varied by adjusting the ratio of the punched area of the punched hole 13 to the area of the first support arm pieces 3 and 3, and the spring constant can be changed depending on the material used and the plate thickness of the arm pieces 3 and 3. Therefore, in this case, a predetermined spring constant can be obtained by adjusting the number of punched holes 13 and the punched area.

9 and 10 show a third embodiment of the suspension arm according to the present invention. In the suspension arm of this embodiment, the same components as those of the conventional suspension arm 21 described above are designated by the same reference numerals as those in FIGS. 11 and 12. In the figure, the suspension arm 40 has a fixing portion 31 fixed at one end to a biaxial actuator body (not shown), and the other end holds the objective lens 26 via a mounting portion 25. ..

One end of the suspension arm 40 has a thin hinge (elastically displacing portion) 32 with respect to the fixed portion 31.
Is provided with a continuous portion 29 that is integrally connected. Here, the thin hinge 32 is formed so as to have a smaller thickness in the direction perpendicular to the paper surface of FIG. In this continuous section 29,
As shown in FIG. 10, a thin hinge (elastically displacing portion) formed so as to have a reduced thickness in a direction perpendicular to the paper surface of FIG.
Insertion parts 41, 41 formed in a bag shape via 30, 30
Are formed. And these elastic displacement parts 30, 30
Notch holes 30a, 30a are formed in the central portion of the shaft to adjust the elastic displacement force. The other end side insertion portions 41, 41
, The openings are opposed to each other and the one end side insertion portion 4
2, 42 are arranged, and the other end side insertion portions 41, 4 are provided.
As shown in FIG. 10, the arm main body 44, 46 is made of a thin non-magnetic metal plate material in the first and the one end side insertion portions 42, 42 and each opening.
Is inserted and held.

The one end side insertion portions 42, 42 are provided with a continuous portion 23 shown in FIG. 9 via an elastic displacement portion 24 which is a thin hinge formed thin in the vertical direction in the drawing of FIG. .. Then, cutout holes 24a, 24a are formed in the central portions of the elastic displacement portions 24, 24 to adjust the elastic displacement force. Further, in front of the connecting portion 23, an attaching portion 25 with the movable body 27 supporting the objective lens 26 shown by phantom lines is integrally molded, and a connecting portion between the connecting portion 23 and the attaching portion 25 is illustrated. The thin hinge portion (elastically displacing portion) 28 is thin in the horizontal direction on the paper surface of FIG. A cutout hole 28a is also formed in the center of the elastic displacement portion 28 to adjust the elastic displacement force.

This embodiment is constructed as described above,
The suspension arm 21 applies a focus coil drive current (not shown) attached to the movable body 27, so that the movable body 27 causes the thin hinge portions (elastic displacement portions) 24, 24 and 30, 30 of the support arms 22, 22 to move. The focus is controlled by elastically displacing the objective lens 26 in the optical axis direction. Then, by applying a drive current to the tracking coil, the movable body 27 elastically displaces the thin hinge portion (elastic displacement portion) 28 and the objective lens 26.
Can be controlled in the direction orthogonal to the optical axis for tracking control. The operation up to this point is similar to that of the conventional suspension arm.

In this embodiment, since the arm main body 44 is made of a metal plate material, the expansion and contraction due to temperature change is greatly reduced as compared with the conventional case where the arm main body 44 is made of a resin support arm. be able to. As a result, it is effective that the optical disc and the engineering pickup do not tilt due to the displacement of the objective lens and so-called skew is not generated, and the field of view of the objective lens with respect to the signal recording surface of the optical disc becomes improper. It can be prevented.

The suspension arm of this embodiment can be easily manufactured by pressing the arm bodies 44, 46 and outsert molding the entire body including the resin portion. Moreover, since the arm body 44 is preferably made of a non-magnetic thin metal plate, the objective lens 1
It goes without saying that the magnetic field generated in the focus coil and the tracking coil, the magnet, and the yoke, which are the driving device of No. 2, does not affect the movement of the arm body 44, and the biaxial operation of the objective lens 12 can be performed accurately. ..

The present invention is not limited to the embodiments described above and shown in the drawings, and various modifications can be made without departing from the scope of the invention. For example, the first
In the embodiment, the elastic displacement portion 6 of the second support arm piece 4 is
Is not necessarily the punched hole 5 as in the embodiment,
Other processing methods may be used as long as the arm piece 4 is elastically deformable in the tracking direction.

[0034]

As described above, in the suspension arm of the objective lens according to the present invention, since the arm member is made of the non-magnetic metal plate, the influence of temperature change can be reduced, and the skew, the field of view of the objective lens and the objective lens can be reduced. It is possible to suppress a change such as a positional deviation.

[Brief description of drawings]

FIG. 1 is a perspective view of a suspension arm according to a first embodiment of the present invention.

FIG. 2 is a plan view of a suspension arm according to a first embodiment of the present invention, in which an objective lens side is shown by an imaginary line.

3 is a side view of the suspension arm of FIG. 2 of the present invention.

FIG. 4 is a plan view of a biaxial actuator using a suspension arm according to the first embodiment of the present invention.

FIG. 5 is an exploded perspective view of a press-molded arm material.

FIG. 6 is a perspective view of an arm material in which a hook portion is bent.

FIG. 7 is a perspective view of the arm member when bending is completed.

FIG. 8 is a perspective view of a second embodiment of a suspension arm according to the present invention.

FIG. 9 is a perspective view of a suspension arm according to a third embodiment of the present invention.

FIG. 10 is a plan view of a suspension arm according to a third embodiment of the present invention, in which an objective lens side is shown by an imaginary line.

FIG. 11 is a plan view of a conventional suspension arm, showing the objective lens side in phantom.

FIG. 12 is a side view of a conventional suspension arm.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Suspension arm 1a Arm member 2 Connection part 3 1st support arm piece 3b Punching hole 4 2nd support arm piece 5 Punching hole 6 Elastic displacement part 7,8 Attachment part 9 Reinforcement part 11 Fixed support body 12 Objective lens 13 Movable body 14 Coil 15 Yoke 16 Magnet 40 Suspension arm 44 Arm body

Claims (4)

[Claims] 1. A first supporting arm piece which is made of a non-magnetic thin metal plate and is bent in parallel from a predetermined continuous portion so as to face each other, and the first supporting arm piece is opposite to the first supporting arm piece. In a direction, the arm member is composed of a second support arm piece that is continuously provided in the continuous portion so as to be orthogonal to the surface of the arm piece, and each of the first and second support arm pieces is provided. A suspension arm for an objective lens, characterized in that a mounting portion for mounting a fixed support body and a movable body holding the objective lens by resin molding is provided at an outer end portion. 2. The suspension arm for an objective lens according to claim 1, wherein a plurality of punched holes are formed in the first support arm piece in the width direction thereof. 3. A suspension arm of an objective lens, one end of which is fixed to a biaxial actuator main body and the other end of which holds an objective lens, wherein resin suspension hinges are provided on one end side and the other end side of the suspension arm, respectively. A suspension arm for an objective lens, wherein an arm body connecting the one end side and the other end side is made of a metal plate. 4. The suspension arm for an objective lens according to claim 3, wherein the arm body is made of a non-magnetic thin metal plate material.