JP3973269B2 - Optical head - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical head in an optical information reproducing apparatus.
[0002]
[Prior art]
Examples of an optical component fixing mechanism for fixing a holder containing an optical component such as a lens used in an optical head so as to be movable in the optical axis direction are disclosed in, for example, JP-A-1-267842 and JP-A-2-244431. ing. Both of these devices can move the holder in the direction of the optical axis by pressing a cylindrical holder containing a lens against two planes that intersect at about 90 degrees formed on the housing using a leaf spring. It has a fixed structure.
[0003]
In the device of Japanese Patent Laid-Open No. 1-267842, the leaf spring is fixed by inserting a folded portion provided at the lower end portion thereof into a groove formed in the housing. Further, in the device disclosed in Japanese Patent Laid-Open No. 2-244431, the leaf spring is fixed to the housing with a screw.
[0004]
[Problems to be solved by the invention]
However, it is difficult to achieve miniaturization, cost reduction, and sealing in the optical head with any of the above-described apparatuses.
In other words, since each device holds the holder with a flat spring, the holding force amount of the spring is small, and if the holding force amount is increased, the space for the spring becomes large, and the optical head is miniaturized. I can't plan.
[0005]
In addition, the optical head must have a sealed structure to prevent dust from entering inside (especially around the light source and the photodetector), but it requires an opening for inserting a holder and leaf spring. Since the holder, the two flat surfaces against which the holder is pressed, and the leaf spring are both exposed, it is difficult to form a sealed structure. In order to seal the inside of the optical head, another sealing member such as a lid or a seal is required, and it is difficult to reduce the cost.
[0006]
Furthermore, in the apparatus disclosed in Japanese Patent Laid-Open No. 1-267842, the leaf spring has a complicated shape and requires a large amount of bending because it is provided with a folded-back portion for retaining and a positioning stopper. It is high. Moreover, in order to ensure the holding strength of the insertion portion that can sufficiently withstand the force of the leaf spring, it is necessary to have a size corresponding to the insertion portion, so that the size cannot be reduced. Furthermore, since it is fixed by inserting the folded portion into the groove, it is difficult to disassemble once assembled.
[0007]
Further, in the device disclosed in Japanese Patent Laid-Open No. 2-244431, the plate spring is fixed with a screw, so that a screw and tapping are necessary, and the cost is high. In addition, it is necessary to secure a space for the head of the screw, which is a factor that hinders downsizing.
[0008]
The present invention has been made in view of such circumstances, as its object, to provide an optical head holding force of the holder is to allow high and downsizing or thinning.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, the optical head of the present invention has a housing in which a through hole into which a holder accommodating an optical component is inserted and a hole into which a lens adjustment pin having an eccentric pin at the tip is inserted are formed. And a U-shaped leaf spring member that presses the holder inserted into the through hole, and the hole extends perpendicular to the direction in which the leaf spring member presses the holder, and extends into the through hole. The holder has a groove formed on the outer peripheral surface, the lens adjustment pin is inserted into the hole, the eccentric pin is disposed in the groove of the holder, and the adjustment pin is rotated. The holder is moved in the optical axis direction, the holder is fixed to the casing by the elastic force of the leaf spring member, the casing has a recess partly connected to the through hole, The leaf spring member is In a state where the slider is not inserted into the through hole, the leaf spring member held by the concave portion is held on the straight line passing through the center of the holder inserted into the through hole. There are two straight parts parallel to each other, and the plate spring member is always pushed in a certain direction by the holder inserted into the through-hole, so that the holder is always pressed in a fixed direction and the holder is stably fixed. characterized in that it.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows a schematic configuration of a general optical head that employs a separation optical system. As shown in FIG. 1, the optical head includes a fixed portion 10 fixed to an apparatus main body (not shown) and a movable portion 20 supported by two guide rails 30 so as to be movable in the radial direction of the disk 50. And a voice coil motor 40 for moving the movable portion 20.
[0017]
The light beam emitted from the fixed unit 10 is focused on a disk 50 as a recording medium through a rising mirror 22 and an objective lens 24 provided inside the movable unit 20. The light reflected by the disk 50 travels back along the optical path leading to it and returns to the fixing unit 10. The fixing unit 10 detects recording information, information necessary for detecting a focus error and a tracking error based on the return light from the disk 50.
[0018]
The structure of the fixing part of the optical head according to the embodiment of the present invention is shown in FIGS.
As shown in FIGS. 2 to 4, the rear side of the base 110, which is the housing of the fixed portion of the optical head, is an opening and a recess 112 is provided. The integrated optical head 120 is fixed to the base 110 with screws 130 so as to close the opening of the base 110 and so that the light source unit 122 is accommodated in the recess 112. The integrated optical head 120 is a small optical head in which, for example, what is disclosed in JP-A-8-45127 is packaged in a sealing can.
[0019]
A through hole 114 into which a cylindrical holder 150 with a collimating lens 140 is inserted is formed on the front surface of the base 110, and a U-shaped leaf spring 160 is accommodated near the through hole 114. A recess 116 is formed. The through hole 114 and the recess 116 are partially connected to each other, and the through hole 114 is connected to the rear recess 112, but the recess 116 is separated from the recess 112 by the wall 117.
[0020]
As for the assembly of the leaf spring 160 and the holder 150, the leaf spring 160 is first disposed in the recess 116, and then the holder 150 is inserted into the through hole 114.
The U-shaped leaf spring 160 is narrowed at the open end as shown in FIG. 5A, and in this state is pushed into the recess 116 as shown in FIG. 5B. Thereafter, the holder 150 is inserted into the through hole 114, and the leaf spring 160 is slightly pushed away by the holder 150 as shown in FIG.
[0021]
In order to facilitate insertion, the holder 150 preferably has a chamfered portion 154 formed by chamfering a corner as shown in FIG. Alternatively, as shown in FIG. 6B, it has a rounded portion 156 formed by rounding corners.
[0022]
For the same reason, the leaf spring 160 is preferably rounded at the outer corner, which is a portion in contact with the holder 150, as shown in FIG. This is easily realized by selecting the punching side outside the leaf spring 160 in a rectangular plate material punched by a press or the like which is an original member of the leaf spring 160.
[0023]
The leaf spring 160 pushed into the recess 116 is held in the recess 116 by its own restoring force. Further, since the holder 150 inserted into the through hole 114 has pushed the leaf spring 160 away, the holder 150 is held in the through hole 114 by the restoring force of the leaf spring 160. Accordingly, both the leaf spring 160 and the holder 150 are stably held without dropping during the assembly.
[0024]
After the holder 150 is inserted into the through hole 114, the position of the collimator lens 140 in the optical axis direction is adjusted in accordance with the light emitting point of the integrated optical head 120. This position adjustment is performed by inserting a lens adjustment pin 180 into the hole 118 and rotating it in FIG.
[0025]
As can be seen from FIGS. 2 and 4, a groove 152 is formed near the center of the outer peripheral surface of the holder 150, and a hole 118 connected to a through hole 114 into which the holder 150 is inserted is formed in the base 110. Is formed. As shown in FIG. 4, the lens adjusting pin 180 is provided with an eccentric pin 182 at the tip thereof at a position off the center.
[0026]
The lens adjustment pin 180 is inserted into the hole 118 and the eccentric pin 182 is disposed in the groove 152 of the holder 150. By rotating the lens adjustment pin 180 in this state, the holder 150 passes through the through hole 114 in its axial direction. Is moved along. By this operation, the position of the collimating lens 140 can be adjusted according to the light emitting point of the integrated optical head 120.
[0027]
Although not specifically mentioned so far, various types of fittings between the cylindrical holder 150 and the through hole 114 into which the cylindrical holder 150 is inserted can be applied. For example, as shown in FIG. 7A, a type in which a cylindrical holder 150 is received by a cylindrical through hole 114 may be used. In this case, the fit should be fairly good. For example, the fit tolerance should be 0 to +0.03 for the through hole 114 and −0.030 to −0.001 for the holder 150.
[0028]
Alternatively, as shown in FIG. 7B, the holder 150 may be received by two ridgelines using a through hole 114 in which a relief groove is formed in a portion where the holder 150 is pressed. In this configuration, the holder 150 is stabilized, and rattling of the holder 150 in the through hole 114 is suppressed. In this case, since the position of the holder 150 is determined if the dimension A in the figure is determined, the fitting may be slightly looser than that in FIG.
[0029]
Alternatively, as shown in FIG. 7C, the holder 150 may be of a type that receives on two planes. With this configuration, the same effect as in FIG. 7B can be expected. In this case, if the positions of the two planes, that is, the dimensions of B and C are determined, the position of the holder 150 is determined.
[0030]
The U-shaped leaf spring 160 can have various shapes. For example, as shown in FIG. 8A, the leaf spring 160 may be simply a rectangular plate material bent into a U-shape, which can be manufactured most simply and inexpensively. The punched shape is rectangular, has no holes, and is a very simple shape that only needs to be bent once in one direction, and can be manufactured at low cost.
[0031]
As shown in FIGS. 8 (b1) and 8 (b2), the leaf spring 160 may be formed with projections 162 projecting outward by drawing at four corners. Providing the protrusion 162 ensures that the contact point between the holder 150 and the leaf spring 160 is at both ends. As a result, the holder 150 is always pushed at the same distance and becomes a more stable hold.
[0032]
Further, when the plate spring 160 having this structure is used, as shown in FIG. 6C, the holder 150 does not hit the end of the plate spring 160 at the time of insertion, but only hits the protrusion 162. There is an advantage that the insertion can be performed more smoothly.
[0033]
Further, as shown in FIG. 8C1, the leaf spring 160 has protrusions 162 protruding outward on both sides of one end, and a notch 164 is provided on the opposite end. May be. In this case, as shown in FIG. 8 (c2), the recessed portion 116 into which this is pushed is preferably provided with a stepped portion 116a that matches the notch 164. The notch 164 of the leaf spring 160 and the stepped portion 116a of the recess 116 restrict the orientation of the plate spring 160 that can be assembled to one, so that the protrusion 162 is always in the correct posture facing the through hole 114. A spring is attached.
[0034]
In addition, the top of the protrusion 162 may become rough due to drawing or the like, and the sliding with the holder 150 may be deteriorated. In this case, as shown in FIG. 8D, a seal 166 that improves slipping may be attached to the leaf spring 160. Alternatively, instead of applying the seal 166, grease or an uncured adhesive may be applied and cured after adjustment.
[0035]
In addition, as shown in FIG. 9, the leaf spring 160 is preferably provided with two straight portions D and E on a straight line passing through the center of the holder 150. In this structure, a force acts on the linear portion D and the linear portion E so as to open in a substantially horizontal direction. Therefore, the holder 150 is always pushed in a certain direction, which is very effective for stable fixing of the holder 150.
[0036]
Regarding the force amount setting of the leaf spring 160, the lower limit value is a force amount that does not allow the holder 150 to move even when an impact is applied, and the upper limit value is a strength that allows the holder to move when adjusting the position of the holder. Must be realized below the elastic limit.
[0037]
For example, in order to withstand the impact of 200 G assuming that the total mass of the lens 140 and the holder 150 is 1 g, if the friction coefficient is set to 0.4 and the spring force amount is 2 Kgf, the holding force amount is 800 gf, and the safety factor is 4 times. Can hold. Although it is a calculation that can endure an impact of 800G, in reality, it does not receive such a severe impact.
[0038]
Therefore, when the amount of operation force at the time of adjustment is calculated, as shown in FIG. 10, if the amount of eccentricity of the eccentric pin is 0.5 mm and the thickness of the operation portion is 5 mm, 800 gf × 0.5 ÷ 5 = 80 gf · mm. . If it is about this level, it can be sufficiently adjusted manually.
[0039]
The plate thickness, bending radius, plate width, and amount of deflection are selected so that the elastic material is below the elastic limit value. In FIG. 11, the formula for calculating the stress σ of the U-shaped leaf spring 160 is
δ = (PR ³ /B){0.333(λ ³ + μ ³ )
^{+ Λ 2 (π + μ)} + λ (4-μ 2) + 0.5π}
It is represented by Where B = bh ³ E / 12 (1-ν ² ), λ = l ₁ / R, μ = l ₂ / R
Where E is the longitudinal elastic modulus of the material, ν is the Poisson's ratio, b is the plate width, h is the plate thickness, and R is the bending radius.
[0040]
When SUS301CSP-H is used as a material and b = 0.4 mm, H = 4 mm, R = 2 mm, l ₁ = 3.3 mm, l ₂ = 0, and δ = 0.2 mm, stress σ = 6PR (λ + sin β ) / Bh ² = 99.4 Kgf / mm ² , which is less than the allowable stress (105 Kgf / mm ² ) of the material (SUS301CSP-H), and is valid in design.
[0041]
Therefore, the adjustment by the eccentric pin 180 is sufficiently possible, but the adjustment position can be prevented from shifting even when an impact is applied.
By using the U-shaped leaf spring 160, there is an effect that a large holding force (elastic force) is obtained, but a large space is not required to accommodate this. That is, since the distance between the two operating points, that is, the contact point between the leaf spring 160 and the recess 116 and the contact point between the leaf spring 160 and the holder 150 is long, a large elastic force can be obtained. The reason why the size can be reduced is that the linear distance between the two action points (the distance in the horizontal direction in FIG. 5C) is short, and the recess 116 that accommodates the distance can be designed to be small.
[0042]
The holder 150 that holds the collimating lens 140 is inserted into the through hole 114 of the base 110, so that hermetic sealing is performed during the holder mounting process. Therefore, the inside of the base in which the light source unit and the photodetector are accommodated can be sealed, and other processes such as sealing are not necessary. In addition, a sealing member (lid member or seal member) for sealing is not necessary.
[0043]
In FIG. 2, the fixing portion 10 is fixed to the apparatus main body (not shown) by screws 170, and as a result, the opening of the concave portion 116 on the side where the leaf spring 160 is inserted is closed. Is firmly determined and will not shift.
[0044]
In this way, the base 110 of the fixed portion has a strong and simple box shape without an undesired opening when attached to the apparatus main body, and thus has a high strength. Further, deformation of the base 110 due to temperature change or the like can be minimized.
The present invention is not limited to the above-described embodiment. All implementations performed without departing from the scope of the invention are included in the present invention.
[0045]
【The invention's effect】
According to the present invention, it is possible to provide an optical head that is reduced in size or thickness.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a schematic configuration of a general optical head employing a separation optical system.
FIG. 2 is an exploded perspective view of a fixing portion of the optical head according to the embodiment of the present invention.
FIG. 3 is a cross-sectional view of the fixed portion shown in FIG. 2 in an assembled state.
4 is a longitudinal sectional view of the fixed part shown in FIG. 2 in an assembled state. FIG.
5 shows how the U-shaped leaf spring shown in FIG. 2 is assembled in the recess.
6 shows how the holder shown in FIG. 2 is inserted into the through hole.
7 shows various shapes applicable as the through hole shown in FIG.
8 shows various shapes applicable as the leaf spring shown in FIG.
FIG. 9 shows a preferred U-shaped leaf spring having two straight portions parallel to each other.
FIG. 10 shows an example of a lens adjustment pin together with specific dimensions.
FIG. 11 shows various parameters for calculating the stress of a U-shaped leaf spring.
[Explanation of symbols]
110 Base 114 Through-hole 116 Recess 140 Collimate lens 150 Holder 160 Leaf spring

Claims (1)

In an optical head capable of adjusting the position of a holder containing optical components in the optical axis direction, a housing in which a through hole into which the holder is inserted and a hole into which a lens adjustment pin having an eccentric pin at the tip is inserted are formed. And a U-shaped leaf spring member that presses the holder inserted in the through hole, and the hole extends perpendicular to the direction in which the leaf spring member presses the holder, and the through hole The holder has a groove formed on the outer peripheral surface thereof, the lens adjusting pin is inserted into the hole, the eccentric pin is disposed in the groove of the holder, and the adjusting pin is rotated. The holder is moved in the optical axis direction, the holder is fixed to the casing by the elastic force of the leaf spring member, and the casing has a recess partly connected to the through hole, The leaf spring part Is held in the recess by its own elastic force when the holder is not inserted into the through hole, and the leaf spring member held in the recess is a straight line passing through the center of the holder inserted in the through hole. There are two linear parts parallel to each other, and the leaf spring member is always pushed in a certain direction by the linear part being slightly pushed away by the holder inserted in the through hole, so that the holder is stabilized. An optical head characterized by being fixed to the head.

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