KR100304477B1 - Optical pickup - Google Patents

Abstract

The present invention provides an improved optical pickup device which prevents the movable portion having the objective lens from being rolled by an external force. Upper and lower pairs of suspension wires may be provided to connect the movable parts to the suspension base on the base substrate to fix the movable parts in the focal direction of the objective lens. The upper and lower pair of suspension wires are asymmetrically mounted with respect to the center of gravity of the movable portion in the height direction of the movable portion. The suspension base includes a spring portion for connecting one end of the upper and lower pair of suspension wires. The spring portion includes a first spring portion positioned higher than the gravity center in the height direction and a second spring portion positioned lower than the gravity center. The first spring constant of the first spring portion is configured differently from the second spring constant of the second spring portion to prevent the movable portion from rolling.

Description

Optical pickup

The present invention relates to an improved optical pickup device for recording and reproducing information on an optical disc, an optical magnetic disc, or the like, and more particularly, to an optical pickup device capable of fixing the attitude of an optical pickup objective lens even when an impact or acceleration is applied from the outside. will be.

In optical discs such as compact discs (CDs), video discs (VDs), CD-ROMs (Read Only Memory) or magneto-optical discs, information signals such as sound information, picture information or character information are converted into a series of feet, It is known that this series of pits are recorded spirally or concentrically on an optical disc.

Various structures of the optical pickup apparatus are used to precisely irradiate light beam spots on the recording tracks of the optical disc to focus-control the objective lens along the optical axis and track-control the objective lens in the radial direction of the recording track. Japanese Patent Laid-Open No. 62-40627 / 1987 discloses an optical pickup device in which an optical beam spot from an objective lens is always irradiated onto a recording track even when an impact or acceleration is applied in the track direction of the optical disc.

1 is an exploded perspective view showing a conventional optical pickup device.

FIG. 2 (a) is a plan view of FIG. 1, and FIG. 2 (b) is a side cross-sectional view of FIG.

The optical pickup device 100 shown in FIGS. 1 and 2 (a) and 2 (b) is in the form of a plate. In the center of the base substrate 101, the opening portion 101a extends along the front and rear directions of the base substrate 101. In addition, the platform 101b protrudes from the distal end of the opening 101a and the distal end of the base substrate 101 to the upper portion of the base substrate 101. A pair of inner yokes 101c and 101c facing each other are provided protruding adjacent to the sidewalls of the opening 101a, and the opening is located between the pair of inner yokes, and the inner yoke ( A pair of outer yokes 101d and 101d respectively facing at a predetermined distance from 101c are provided outside the pair of inner yokes 101c. A pair of magnets 102 and 102 are fixed to the inner walls of the pair of outer yokes 101d and 101d respectively facing the inner yoke 101c.

A support arm 103 rotatably supporting the movable portion 106 to be described later is fixed to the platform 101b using bolts 104 and 104. The support arm 103 is integrally made of an elastic resin that is elastically deformable.

The support arm 103 is thinly made of a base 103a and an elastic resin connected to the upper and lower ends of the base 103a and rotatably rotated in a focal direction, i.e., an up and down direction, indicated by a double-headed arrow Y. A pair of elastic members 103b disposed, a pair of parallel links 103c provided respectively at distal ends of the pair of elastic members 103b, and end portions of the pair of parallel links 103c, It consists of the H-type hinge 103d which has the thin film member 103d1 which rotatably arranges the movable part 106 in the track direction shown by the double arrow X. As shown in FIG.

Here, the center line 103d2 passing through the center point of the H-shaped hinge 103d is designed to coincide with the gravity center G of the movable part 106 shown in FIG. 2 (a).

The movable part 106 for installing the objective lens 105 is formed to have the same height as that of the H-type hinge 103d. The movable portion 106 is integrally formed with a base member 106a and a pair of arms 106d extending rearward from an end of the base member 106a. The movable portion has a lens hole 106b on the upper surface of the base member 106a for installing the objective lens 105 and a balance hole below the lower portion of the base member 106a for providing the ring balancer 107. 106c, a pair of hinge grooves 106e and 106e for engaging the H-shaped hinge 103d of the support arm 103, and a pair for supporting the pole balancer 108 inserted therebetween. A pair of balance holes 106f and 106f at the end of the arm 106d is defined.

In addition, the drive coils 109 and 109 are fixed to both sides of the movable section 106, respectively. Each of the drive coils 109 is composed of a focus coil 109a and a track coil 109b provided outside the focus coil 109a. Each of the focusing coils 109a, 109a is loosely fitted with an inner yoke 101c that is not in contact with it, as shown in FIG. 2 (a).

As shown in FIG. 2 (a) and FIG. 2 (b), in the focus adjustment operation state of the optical pickup device 100 of the prior art, a focus adjustment signal is paired from a focus adjustment signal supply unit (not shown). To the focus coil 109a. Therefore, the pair of parallel links 103c of the support arms 103 are in the focal direction shown by arrows Y (up and down directions) generated by the magnetic field formed between the magnet 102 and the inner yoke 101c. It is displaced. The light beam spot from the objective lens 105 is focused on the recording track of the optical disc D along the optical axis of the objective lens 105 by the elastic deformation of the elastic member 103b of the pair of parallel links 103c. Is adjusted to fit.

Further, in the track adjustment operation state, the track adjustment signal is supplied from the track adjustment signal supply portion (not shown) to the pair of track coils 109b. The pair of parallel links 103c of the support arms 103 are arranged in the track direction X generated by the magnetic field formed between the magnet 102 and the inner yoke 101c. From the objective lens 105, the light beam swab is adjusted to be positioned in the radial direction of the optical disk D by the elastic deformation of the H-shaped hinge 103d of the support arm 103, so that from the objective lens 105 The light beam spot is adjusted to be traced on the desired recording track in the track direction X.

In the optical pickup device 100 of the prior art, the center point of the H-shaped hinge 103d is designed to coincide with the line passing through the center of gravity of the movable portion 106, so that the objective lens 105 may be subjected to impact and acceleration from the outside. Does not deviate easily from the recording track.

However, the conventional optical pickup device 100 has a drawback that it is difficult to reduce its dimensions.

In detail, as shown in FIG. 2 (b), under the ring balancer 107 of the movable part 106, a mirror M inclined at 45 ° with respect to the optical axis of the objective lens 105 may be provided. There is a need. The mirror M reflects the light beam emitted from the semiconductor laser L in the direction of the optical disk D through the objective lens 105, and the light beam reflected by the optical disk D is the objective lens 105. ) Is directed to the photodetector F reflected at right angles by the mirror M.

Therefore, when the ring balancer 107 is provided below the objective lens 105, it is impossible to position the mirror X adjacent to the objective lens 105, and as a result, the optical pickup device 100 in the height direction thereof. ) It is difficult to reduce the dimensions.

If the ring balancer 107 is removed from the portion by the structure of the optical pickup device 100 to reduce the dimensions of the optical pickup device, the optical pickup device 100 loses its balance, and consequently an external shock or Acceleration causes the optical pickup device to roll.

The optical pickup device without the ring balancer 107 cannot be applied portable or for automotive use.

It is therefore a general object of the present invention to provide an optical pickup apparatus in which the above drawbacks are eliminated.

Another object of the present invention is to provide an optical pickup apparatus capable of reliably fixing the attitude of the objective lens of the optical pickup even when an impact or acceleration is applied to the optical pickup apparatus from the outside.

Still another object of the present invention is to provide an optical pickup apparatus capable of reducing the thickness of the optical pickup apparatus by providing a reflection mirror near the objective lens of the pickup apparatus.

It is still another object of the present invention to provide an optical pickup apparatus for recording / reproducing a signal to / from a track of a recording disc using an optical beam spot, comprising: an objective for focusing an optical beam spot on a base substrate and a track of the optical disc; Movable part for mounting a lens, a suspension base fixed to the base substrate, and a pair of upper and lower suspensions for connecting the movable part to the suspension base in such a way that the movable part is displaced in the focal direction of the objective lens. And a pair of upper and lower suspension wires are asymmetrically mounted with respect to the center of gravity of the movable portion in the height direction of the movable portion, and the suspension base includes one end of the pair of upper and lower suspension wires. An additional spring portion for connection, said spring portion being a gravity center beam of the movable portion A first spring portion positioned higher and a second spring portion positioned below the center of gravity in the height direction of the movable portion, wherein the first spring constant of the first spring portion prevents the rolling of the movable portion generated by an external force; In order to provide an optical pickup device configured differently from the second spring constant of the second spring portion.

1 is an exploded perspective view showing a conventional optical pickup device.

Fig. 2 (a) is a plan view of Fig. 1, and Fig. 2 (b) is a side cross-sectional view of Fig. 2 (a).

3 is an exploded perspective view for explaining the configuration of the first embodiment of the optical pickup device according to the present invention.

4 (a) is a plan view showing a first embodiment of an optical pickup device.

4 (b) is a side view of FIG. 4 (a).

4 (c) is a rear view of FIG. 4 (a).

5 is a perspective view showing a first embodiment of an optical pickup device according to the present invention.

Figure 6 (a) is a perspective view of the suspension base shown in FIG.

6 (b) is a plan view of FIG. 6 (a).

FIG. 6 (c) is a rear view of FIG. 6 (a).

Fig. 7 (a) is a side view schematically showing the operation state of the suspension wire and the suspension base of the first embodiment of the optical pickup device.

7 (b) is a rear view schematically showing the 7 (a).

Fig. 7 (c) is a schematic diagram for explaining the operating states of the suspension wire and the suspension base of the first embodiment of the optical pickup device.

8 (a) is a plan view showing a first embodiment of an optical pickup device.

Fig. 8 (b) is a side view of Fig. 8 (a), and Fig. 8 (c) is a rear view of Fig. 8 (a).

9 (a) is a perspective view showing the suspension base shown in FIGS. 8 (a) to 8 (c).

9 (b) is a plan view of FIG. 9 (a).

Figure 9 (c) is a rear view of Figure 9 (a).

10 (a) is a side view schematically shown for explaining the operating states of the suspension wire and the optical base of the second embodiment of the optical pickup device.

10 (b) is a rear view schematically shown in FIG. 10 (a).

10 (c) is a schematic diagram for explaining the tenth (a).

* Explanation of symbols for main parts of the drawings

1A, 1B: Optical pickup device 2: Base

4: movable part 5: objective lens

7: Balancer 9a: Upper side

11d: 1st spring part 11e: 2nd spring part

Other objects and additional features of the present invention will be described in detail with reference to the accompanying drawings.

Hereinafter, the first and second embodiments according to the present invention will be described with reference to the drawings of FIGS. 3 to 10 (c).

3 is an exploded perspective view for explaining the configuration of the first embodiment of the optical pickup device according to the present invention.

FIG. 4 (a) is a plan view showing a first embodiment of the optical pickup device, FIG. 4 (b) is a side view of FIG. 4 (a), and FIG. 4 (c) is a rear view of FIG. 4 (a).

5 is a perspective view showing a first embodiment of an optical pickup device according to the present invention.

FIG. 6 (a) is a perspective view showing the suspension base shown in FIG. 3, FIG. 6 (b) is a plan view of FIG. 6 (a), and FIG. 6 (c) is a rear view of FIG.

FIG. 7 (a) is a side view schematically showing the operation state of the suspension wire and the suspension base of the first embodiment of the optical pickup device, and FIG. 7 (b) is a back view schematically showing the seventh (a) view FIG. 7 (c) is a diagram schematically illustrating an operation state of the suspension wire and the suspension base of the first embodiment of the optical pickup device.

Referring to FIG. 3, in the optical pickup device 1A of the first embodiment of the present invention, the base substrate 2 is formed integrally as a rigid frame structure using a soft magnetic material. In the center of the base substrate 2, the opening part 2a extends along the front-back direction. The opening 2a is used as an optical path of the light beam reflected by the mirror M through the objective lens 5 to be described later.

Further, the bridge board 2b protrudes from the left side and the right wall of the opening portion 2a to the upper portion of the opening portion 2a on the front surface of the opening portion, so that the mirror M is provided with the bridge board 2b. ) Can be located at the bottom.

Between the end of the opening portion 2a and the rear end of the base substrate 2, a pair of support bases 2c protrude upwardly facing each other on the upper surface of the base substrate 2. A pair of notches 2c1 and 2c1 may be provided on the upper surfaces of the pair of support bases 2c and 2c so that the suspension base 11A, which will be described later, may be installed or supported on the notch 2c1.

In addition, a pair of inner yokes 2d and 2d protruding upward and adjacent to the left and right walls of the opening portion 2a and facing each other, the base substrate (outside the inner yokes 2d and 2d) 2) A pair of outer yokes 2e and 2e are provided above and the outer yokes 2e and 2e face at predetermined intervals. A pair of magnets 3 are fixed to the wall of the inner yoke 24 so as to be mounted between the inner yoke 2d and the outer yoke 2e.

In addition, a pair of attachment bases 2f and 2f facing each other protrude upward from the sidewall of the base substrate 2 and are mounted between the bridge board 2b and the outer yokes 2e and 2e, respectively. The pair of protrusions 2f1 and 2f1 protrude from the top of the pair of attachment bases 2f in the outward direction of the base substrate 2. The pair of protrusions 2f1 and 2f1 are supported by a pair of notches Iv respectively provided on top of the moving plate I as clearly shown in FIG.

Next, the movable part 4 for mounting the objective lens 5 will be described.

The movable portion 4 comprises an objective lens 5, a lens holder 6 for installing the objective lens 5, a pair of drive coils 8 and two pairs of suspension wires 9 A pair of suspension wires 9a provided on the upper surface of the lens holder 6 and a pair of lower suspension wires 9b provided below the lens holder 6 to elastically support the lens holder 6. And a pair of prints provided on the lower and upper surfaces of the lens holder (one of the lower ones not shown) for connecting the ends of the driving coil 8 and for fixing them to one end of the upper and lower suspension wires 9a and 9b. And a circuit board 10. The other ends of the upper and lower suspension wires 9a and 9b are fixed to the suspension base 11A. Two pairs of wires 9 are provided to displace the movable part 4 in the focal direction to be described later.

The lens holder 6 generally consists of a front portion 6a, a rear portion 6c and an intermediate portion 6b, which intermediate portion is provided with a front and rear portion 6a to provide a pair of drive coils 8. , 6c) form a pair of recesses. In the front portion 6a, a lens hole 6a1 is provided in the axial direction on the upper surface for installing the objective lens 5, and a light beam reflected by the mirror M through the objective lens 5 is provided. A through hole 6a2 is provided in the axial direction below the lens hole 6a1 to form an optical path.

In addition, driving coils 8 and 8 are respectively fixed to both sides of the movable part 4. Each of the drive coils 8, 8 is composed of a focus coil 8a and a track coil 8b provided outside the focus coil 8a. Each of the focusing coils 8a and 8a is loosely fixed to the inner yoke 2d without being contacted as shown in FIG. 4 (a). On the upper surface of the rear part 6c of the lens holder 6, a balancer 7 for self-balancing with the objective lens 5 is provided at the center thereof. On the lower and upper surfaces of the rear part 6c, two pairs of grooves 6c1 (one on the lower surface is not shown) are formed so as to be adjacent to the balancer 7 interposed between the pair of grooves 6c1. To provide upper and lower suspension wires 9a and 9b passing radially.

A pair of drive coils 8 facing each other are fixed to the pair of recesses of the intermediate portion 6b as described above.

The upper and lower surfaces of the intermediate portion 6b are provided with a printed circuit board 10 for fixing the ends of the four suspension wires 9 and connecting the ends of the drive coils 8 as described above.

Next, a suspension base 11A for rotatably supporting the movable portion 4 through the suspension wire 9, which is one of the main features of the first embodiment of the present invention, will be described.

The suspension base 11A is formed integrally with the resin which can be elastically deformed.

As shown in an enlarged view in FIGS. 6 (a) to 6 (c), a rectangular base 11a is formed at the center of the suspension base 11A. The square base 11a has a pair of wing plates 11a1 at its side, and has a pair of protrusions 11b projecting forward and backward in the direction of the arrow from the front and rear ends thereof. 11A can be attached to the base substrate 2 such that the pair of protrusions 11b engage with the pair of notches 2c1 and 2c1 of the support base 2c provided on the base substrate 2. Two pairs of grooves 11c (one pair of lower portions are not shown) are formed on the lower and upper surfaces of the pair of wing plates 11a1 and 11a1, respectively, so that the pair of grooves 6c1 of the lens holder 6 are formed. 6c1, the upper and lower suspensions 9a and 9b are inserted radially through the extension line.

In addition, the suspension base 11A has a spring portion S including a pair of first plate springs 11d and a pair of second plate springs 11e.

The pair of first plate springs 11d having a thin thickness are elastically formed in the track direction shown by arrows X at the left and right sides of the rectangular base lea. The height H1 of each of the first plate springs 11d includes the center of gravity G of the movable portion 4 and is defined by a plane of gravity Gm defined as a plane parallel to the upper surface of the lens holder 6. In connection with it, it is small and formed symmetrically.

The height H2 of each of the second plate springs 11e is connected to the ends of the pair of first plate springs 11d so that the pair of second plate springs 11e is connected to the ends of the pair of first plate springs 11d. Greater than H1). On the upper and lower surfaces of the pair of second plate springs 11e, two pairs of guide grooves in the radial direction along the extension lines of the two pairs of grooves 6c1 of the lens holder 6, namely, a pair of upper guides The two pairs of suspension wires 9 are positioned at the same height so that the grooves 11e1 and the pair of lower guide grooves 11e2 are provided. In addition, a pair of upper notches 11e11 are disposed at the same height as the heights of the two pairs of guide grooves 11e1 and 11e1 and 11e2 and 11e2 on the left and right sides of the pair of second plate springs 11e and 11e. ) And a pair of lower notches 11e21 are provided.

In addition, the other end of the pair of upper suspension wires 9a is fixed to the pair of guide grooves 11e1 and the distal end thereof is fitted to the pair of upper notches 11e11, and the pair of lower suspension wires 9b. The other end of) is fixed to a pair of guide grooves 11e2 and its distal end is fitted to a pair of lower notches 11e21.

As shown in FIG. 6 (c), the distance K1 from the lower portion of the upper guide groove 11e1 and the upper notch 11e11 to the gravity plane Gm is the lower guide groove 11e2 and the lower portion. It is made shorter than the space | interval K2 from the lower part of the notch 11e21 to the gravity surface Gm. Therefore, the gaps K1 and K2 are configured asymmetrically with respect to the gravitational plane Gm. As a result, the upper suspension wire 9a and the lower suspension wire 9b are mounted asymmetrically with respect to the gravity plane Gm.

In the first embodiment, when the gap K2 is made smaller than the gap K1 such that both gaps K1 and K2 are symmetrical with the gravitational plane Gm, the total gap K = K1 + K2 becomes smaller. . The small total spacing K not only unstablely supports the suspension wire 9 to the movable portion 4, but also lowers the dimensional accuracy of the optical pickup device 1A.

Therefore, in the first embodiment, the suspension wire 9 forms a gap K2 larger than the gap K1, that is, by forming the gaps K1 and K2 asymmetrically on the gravitational plane Gm. The distance K becomes large enough, and as a result, the movable portion 4 is stably supported by the suspension wire 9.

Hereinafter, the suspension wire 9 will be described.

Referring again to FIG. 3, as described above, one end of the four suspension wires 9 is fixed to the printed circuit board 10 of the lens holder 8, and the other end of the four suspension wires 9 The guide grooves 11c of the wing plate 11a1 of the square base 11a and the lens holder 6 are fixed to the guide grooves 11e1 and 11e2.

Thus, the two extension lines of the pair of upper suspension wires 9a cross each other at virtual points 01 on the upper printed circuit board 10 and the two extension lines of the pair of lower suspension wires 9b are likewise the lower printed circuit board. (10) intersect each other with a second virtual point 02 (not shown). A line passing through the first and second imaginary points (01, 02) is constrained as a virtual center line (0). The center of gravity G of the movable part 4 shown in FIGS. 4 and 7 (a) to 7 (c) is approximately located at the virtual center line 0.

The suspension base 11A is attached to the base substrate 2 by engaging the notch 2c1 of the support base 2c with the protrusion 11b of the suspension base 11A. Subsequently, the suspension base 11A and the base substrate 2 are press-mounted between the spring arms 12a and 12b of the support spring 12 so as to be integral with the lower portion of the base substrate 2 and the surface of the suspension base 11A. Supported. The objective lens of the movable part 4 is covered by the cover 13 which becomes the optical pick-up apparatus 1A as shown in FIG.

Hereinafter, the track operation and the focus operation of the optical pickup device 1A of the first embodiment will be described with reference to FIGS. 4 (a) to 4 (c).

First, when a focus adjustment signal is input to a pair of focus coils 8a, a pair of focus coils 8a are applied to a pair of magnetic fields between a pair of yokes 2d and a pair of magnets 3. The magnetic force is received in the focal direction shown by the arrow Y generated by it. Subsequently, the movable part 4 supported by the four suspension wires 9 is rotatably supported in the upper or lower direction. The objective lens 5 provided on the movable portion 4 is focused along its optical axis, and the light spot from the objective lens 5 is focused on the recording track of the optical disc D. FIG.

In addition, when the track adjustment signal is input to the pair of track coils 8b, the pair of track coils 8b are applied to the pair of magnetic fields between the pair of yokes 2d and the pair of magnets 3. The magnetic force is received in the track direction shown by the arrow X generated by the arrow. Subsequently, the movable part 4 supported by the four suspension wires 9 is rotatably moved in the left and right directions on the imaginary line 0. Therefore, the objective lens 5 provided in the movable section 4 is track-adjusted along the radial direction of the track, and the light spot from the objective lens 5 can be recorded on either of the reproduction tracks of the optical disc D. have.

Hereinafter, the suspension wire 9 and the suspension base 11A will be described with reference to FIGS. 7 (a) to 7 (c).

As shown in Fig. 7 (a) and Fig. 7 (b), the objective lens 5 is provided on the front portion 6a of the lens holder 6, and the lens holder (below the front portion 6a) A part of 6) is cut out to install the mirror M under the objective lens 5. On the other hand, a balancer 7 is provided on the upper surface of the rear portion 6c of the lens holder 6. The center of gravity G of the movable portion 4 provided with the objective lens 5 and the balancer 7 is determined to be located slightly below the upper surface of the lens holder 6 along the imaginary line 0. As a result, the center of gravity G is determined to be located at a position higher than the center of position of the movable part 4 in the height direction.

In addition, the movable part 4 has two pairs of suspension wires 9a and 9b, one end of which is connected to the upper and lower surfaces of the movable part 4 and the other end of which is connected to the upper and lower surfaces of the suspension base 11A. It can be moved elastically relative to the base substrate (2).

As described above, the gap K between the upper and lower suspension wires 9a and 9b is sufficient to stably support the movable portion 4. However, the center of gravity G of the movable part 4 is located above the position center C of the movable part 4, and its position center C is approximately the upper and lower suspension wires 9a and 9b. It coincides with the center of the interval between the up and down. That is, the upper and lower suspension wires 9a and 9b are provided asymmetrically with the gravity center G in the height direction.

Therefore, the state is unstable with respect to acceleration and impact added from the outside, and as a result, the center of gravity G of the movable part 4 is located above its position center C, so that the position center C is a rolling center. It can be understood that the movable part 4 is rolled in the direction shown by the double arrow R.

Thus, in the first embodiment, as shown in FIGS. 7 (b) and 7 (c), the asymmetrical deposition of the suspension wire 9 on the gravity plane Gm of the movable part 4. To compensate for the defect, the plate spring part S is divided into two parts, the first spring part S1 is located above the gravity plane Gm and the second spring part S2 is below the gravity plane Gm. Is located. Specifically, the first spring portion S1 is constituted by a part of the first plate spring 11d positioned on the gravity surface Gm and the suspension wires 9a and 9b, and the second spring portion S2 is gravity It consists of a part of the first plate springs 11d and 11d located below the surface Gm and the gravity plane Gm located below the suspension wire 9b and the second plate spring 11e. In the present invention, the first spring portion 51 is different from the second spring constant S2c of the second spring portion S2 by changing the thicknesses of the first and second plate springs 11d and 11e, for example. 1 has a spring constant (S1c).

Specifically, the first spring constant S1c of the first spring portion S1 is smaller than the second spring constant S2c of the second spring portion S2c according to the gap difference between the gaps K1 and K2 described later. It is large.

As shown in Fig. 7 (c), it is assumed that the external force f is applied to the gravity center 0 of the movable part 4 in the direction indicated by the arrow from the side of the movable part 4. Arrangement of the first spring portion S1 by effectively suppressing rolling of the movable portion 4 to determine the first and second spring constants S1c and S2c of the first and second spring portions S1 and S2. (X) becomes the same as that of the second spring portion S2. The balance condition of the state is determined by the relationship between the following moments:

f1 × k1 = f2 × k2 ‥‥‥‥‥‥ (1)

Here f1 or f2 represents the combined force of the force f applied to the 1st or 2nd spring part S1 or S2 (f = f1 + f2).

In addition, formulas (2) and (3), respectively, representing the relationship between the arrangement X and the combined force f1 or f2 are obtained as follows:

f1 = S1c × X ‥‥‥‥‥‥ (2)

f2 = S2c × X ‥‥‥‥‥ 3

From the above formulas (1), (2) and (3), formula (4) is obtained as follows:

S1c / S2c = k2 / k1 (S1c = S2c × (k2 / k1)) ‥‥‥‥‥ 4

As shown in formula (4), k2 > k1 in the above, and the first spring constant (S1c) of the first spring portion (S1) at the ratio of k2 / k1 ratio to the second of the second spring portion (S2c) By making it larger than the spring constant S2c, the rolling of the movable part 4 can be suppressed in the direction shown by the arrow R with respect to external force or acceleration.

This effectively prevents aberration of the objective lens 5 due to the inclination of the objective lens, and as a result, tracking-off of the objective lens 5 can be eliminated.

The first and second spring portions S1 and S2 are provided on the suspension base 11A so that the objective lens 5 can be positioned near the bottom of the mirror M, and consequently the thickness of the optical pickup device 1A. Can be reduced.

Furthermore, the spring constants of the first left and right plate springs 11d can be provided because the first plate springs 11d may be provided asymmetrically with respect to the centerline passing through the gravity center G of the movable part 4. Each can be optimally changed by changing its thickness in the up and down direction on the gravitational plane Gm.

Second Embodiment

FIG. 8 (a) is a plan view showing a first embodiment of the optical pickup device, FIG. 8 (b) is a side view of FIG. 8 (a), and FIG. 8 (c) is a rear view of FIG. 8 (a).

9 (a) is a perspective view showing the suspension base shown in FIGS. 8 (a) to 8 (c), FIG. 9 (b) is a plan view of FIG. 9 (a), and FIG. It is a rear view of FIG. 9 (a).

FIG. 10 (a) is a side view schematically showing the operation state of the suspension wire and the optical base of the second embodiment of the optical pickup device, and FIG. 10 (b) is a rear view schematically shown in FIG. 10 (a) FIG. 10 (c) is a diagram schematically illustrated to describe the tenth (a).

In the optical pickup device 1B of the second embodiment of the present invention, the shape of the suspension base 11B is partially different from that of the suspension base 11A described in the first embodiment.

Therefore, like parts are designated by like reference numerals used in the first embodiment and detailed descriptions thereof are omitted for simplicity, and new components in the second embodiment are indicated by new reference numerals.

As shown in FIG. 9 (a) and FIG. 9 (b), the suspension base 11B used in the second embodiment has a square base 11a formed at its center and a track by its elastic force. And a pair of spring plates 11f and 11f provided on the left and right sides of the rectangular base 11a so as to be rotatably moved in the direction (direction shown by arrow X). The spring plates 11f and 11f have two parts in the height direction by the thin slits 11g and 11g at a 3: 1 ratio, that is, the upper first plate springs 11f1 and 11f1 and the lower second plate springs 11f2 and 11f2. Each separated.

Upper surfaces of the upper first plate springs 11f1 and 11f1 are provided with upper guide grooves 11f11 and 11f11, the lower part of which is approximately the same height as the lower part of the guide grooves 11c and 11c, and the upper first plate. Sides of the springs 11f1 and 11f1 are provided with notches 11f12 and 11f12, the lower part of which is approximately the same height as the lower part of the upper guide grooves 11f11 and 11f11.

Similarly to the above, the lower guide groove 11f21 is provided at the lower portion of the lower second plate springs 11f2 and 11f2, and the lower portion thereof is approximately the same as the lower portion of the guide grooves 11c and 11c (not shown). Height, and the notches 11f22 are provided on the sides of the lower second plate springs 11f2 and 11f2, the lower part of which is approximately the same height as the lower part of the lower guide grooves 11f21 and 11f21.

Then, one end of the pair of upper suspension wires 9a and 9a is fixed to the pair of upper guide grooves 11f11 and 11f11, respectively, and the distal ends thereof are fitted to the pair of upper notches 11f12 and 11f12. One end of the pair of upper suspension wires 9a, 9a is fixed to the pair of lower guide grooves 11f21 and 11f21, respectively, and its distal end is fitted to the pair of lower notches 11f22 and 11f22.

As shown in Figs. 9 (c) and 10 (c), the upper notches 11f12 and 11f12 and the lower side of the upper guide grooves 11f11 and 11f11 are limited to the gravity plane Gm as described above. The gap K1 is made smaller than the limited distance from the lower portions of the lower notches 11f22 and 11f22 and the lower guide grooves 11f21 and 11f21 to the gravitational plane Gm. The gaps K1 and K2 are made asymmetrical with respect to the gravitational plane Gm. As a result, the upper suspension wires 9a and 9a and the lower suspension wires 9b and 9b are asymmetrical with respect to the gravity plane Gm in the up and down directions.

Similarly, in the second embodiment, if the distance K2 is made smaller by the distance K1 so that both distances K1 and K2 are symmetric about the gravitational plane Gm, then the total distance K = K1 + K2 is much smaller. do. The small overall spacing causes a decrease in the dimensional precision of the optical pickup device 1A and the suspension wire 9 to unstablely support the movable portion 4.

Therefore, in the second embodiment, the gaps K1 and K2 are made asymmetrical with respect to the gravitational plane Gm by making the distance K2 larger than the distance K1, and as a result, the suspension as in the first embodiment. The movable part 4 can be stably supported by the wire 7.

Next, with reference to FIGS. 9A to 10C, the operation of the suspension wire 9 supporting the suspension base 11B and the movable portion 4 will be described.

As shown in FIGS. 9 (a) to 10 (c), in the second embodiment, the drawback that the suspension wire 9 is asymmetrically disposed with respect to the gravity plane Gm of the movable part 4 In order to compensate for this, the plate spring part S has two parts, that is, the first spring part S1 located above the gravitational plane Gm and the second spring part S2 located below the gravitational plane Gm. Divided into. Specifically, the first spring portion S1 is composed of a part of the first plate spring 11f1 positioned on the suspension wire 9a and the surface Gm, and the second spring portion S2 is the suspension wire 9b. And a portion of the first plate spring 11f1 located below the face Gm and a portion of the second plate spring 11f2 located below the face Gm. In the present invention, the first spring portion S1 is different from the second spring constant S2c of the second spring portion S2 by changing the thicknesses of the first and second plate springs 11f1 and 11f2, for example. 1 has a spring constant (S1c).

Specifically, the first spring constant S1c of the first spring portion S1 is the second spring constant S2c of the second spring portion S2c according to the gap difference between the gaps K1 and K2 as described above. It is made bigger.

The above fact can be examined in the same way as mentioned in the first embodiment by using the formulas (1) to (4). As a result, as in the first embodiment, the first spring constant S1c of the first spring portion S1 is made larger than the second spring portion S2 to move in the direction shown by the arrow R with respect to acceleration or external force. The rolling of the possible part 4 can be suppressed.

Specifically, this can be realized by making the spring constant of the first plate spring 11f1 located below the gravity center G as the first embodiment larger than the spring constant of the second plate spring 11f2.

Thereby, the aberration of the objective lens 5 due to the inclination of the objective lens can be effectively prevented, and as a result, the tracking off of the objective lens 5 can be effectively eliminated.

Further, by providing the first and second plate springs 11f1 and 11f2 on the suspension base 11B, it is possible to position the objective lens 5 close to the mirror M below it, and consequently the optical pickup device ( It is possible to reduce the thickness of 1A).

As described above, according to the improved optical pickup device which can prevent the movable part provided with the objective lens from the rolling caused by the external force, the upper and lower pair of suspensions are connected to connect the movable part to the suspension base on the base substrate. A wire may be provided to secure the movable portion in the focal direction of the objective lens. The upper and lower pair of suspension wires are asymmetrically mounted with respect to the center of gravity of the movable portion in the height direction of the movable portion. The suspension base includes a spring portion for connecting one end of the upper and lower pair of suspension wires. The spring portion includes a first spring portion positioned higher than the gravity center in the height direction and a second spring portion positioned lower than the gravity center. The first spring constant of the first spring portion is configured differently from the second spring constant of the second spring portion to prevent the movable portion from rolling. As a result, even if an impulse or acceleration is applied from the outside, the movable portion does not roll, and the phenomenon that the aberration occurs due to tilting of the objective lens can be prevented, so that the objective lens does not cause tracking misalignment. Further, by providing the spring portion in the suspension base, it becomes possible to install the objective lens in close proximity to the mirror below it, thereby achieving a thinning of the optical pickup device of the present invention.

Claims (3)

An optical pickup apparatus for recording / reproducing a signal to / from a track of a recording disc using an optical beam spot, comprising: a base substrate and a movable portion mounted with an objective lens for focusing an optical beam spot on a track of the optical disc And a pair of upper suspension wires and a pair of lower suspension wires connecting the movable base to the suspension base such that the suspension base fixed to the base substrate and the movable part can be displaced in the focal direction of the objective lens. Upper and lower pairs of suspension wires are asymmetrically disposed with respect to the center of gravity of the movable portion in the height direction of the movable portion, and the suspension base further includes a spring portion for connecting one end of the upper and lower pair of suspension wires. And the spring portion in a height direction of the movable portion. A first spring portion positioned higher than the center of gravity of the movable portion and a second spring portion positioned lower than the center of gravity of the movable portion, wherein the first spring constant of the first spring portion is adapted to prevent the movable portion from rolling by an external force. 2 The optical pickup device which is different from the second spring constant of the spring portion. The method of claim 1, wherein the first spacing defined between the first spring portion of the spring portion and the gravity center of the movable portion in the height direction of the movable portion is between the gravity center of the second spring portion and the movable portion. An optical pickup device that is smaller than a defined second interval. The optical pickup apparatus of claim 1, wherein the first spring constant of the first spring portion is greater than the second spring constant of the second spring portion.

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