JP4069429B2 - Objective lens unit - Google Patents

Description

The present invention relates to an objective lens unit used in a disk device such as a DVD player or a DVD recorder, and particularly, cuts unnecessary light with a simple structure.

Conventionally, there is a technique described in Patent Document 1 as a technique of an objective lens unit. An example of the technique will be described with reference to FIGS. 6 to 9. In this case, the objective lens OL is provided on the front portion 1 </ b> A of the lens holder 1. At the same time, a boss 1a is integrally projected at the center of the lens holder 1, a focus coil 5 is provided around the boss 1a, and tracking is performed on both side surfaces from the center to the rear 1B of the lens holder 1. A coil 6 is provided, and a shaft hole 2 penetrating substantially in the center of the lens holder 1 is fitted to the shaft 4 of the act base 3 so that the shaft center O of the shaft 4 serves as a fulcrum. A pair of standing plates 3a are formed so that the weight balance between the portion 1A and the rear portion 1B is substantially balanced, and is raised from both sides of the act base 3 with the lens holder 1 interposed therebetween. A gnet 7 is arranged, and the lens holder 1 is covered with a synthetic resin act cover 8, and a hook portion 8 a integrally projecting from the act cover 8 is detachably engaged with the act base 3, thereby activating the act base. 3 is brought into contact with or close to the top surface of the shaft 4, and a large-diameter opening 9 formed in the top plate 8b is formed by the objective lens O.
The collimator lens QWP, which is loosely fitted to L and faces the objective lens OL, is act base 3
Is provided in the optical pickup main body 10 that supports the optical pickup. Reference numeral 11 denotes a pair of angle adjusting screws that pass through the optical pickup main body 10 and are screwed into the screw holes of the act base 3, and 12 is a presser that is inserted into the insertion hole of the act base 3 and screwed to the optical pickup main body 10. A screw 13 is a coil spring interposed between the head of the presser screw and the act base 3, and 14 is a printed circuit board, which is connected to the focus coil 5 and the tracking coil 6 via a lead wire 14a. . D is a disk.

In the above configuration, by energizing and exciting the focus coil 5, the lens holder 1 is slid in the focus directions a and b along the shaft 4, and the objective lens OL is passed from the semiconductor laser as the light source through the collimator lens QWP. The incident light L entering the laser beam is converged on the recording surface Da of the disk D at a predetermined condensing angle α, and the tracking coil 6 is energized and excited to cause the lens holder 1 to move around the shaft 4 in the tracking direction c, The objective lens OL is caused to follow a predetermined track on the recording surface Da of the disk D (see the phantom line in FIG. 5).
Thereby, the reflected light reflected by the recording surface Da of the incident light L is received by the light receiving element through the objective lens OL and the collimator lens QWP, thereby reading the information recorded on the recording surface Da.
JP 2004-296039 A

According to the above configuration, the weight balance between the front portion 1A and the rear portion 1B of the lens holder 1 is substantially balanced with the axis O of the shaft 4 as a fulcrum, while the shaft hole 2 of the lens holder 1 There is a gap t between the shaft 4 and the gap t is very small.
9 is slid in the focus directions a and b, and is swung in the tracking directions c and d, the inner peripheral surface of the shaft hole 2 partially contacts the outer peripheral surface of the shaft 4 irregularly, as shown in FIG. The lens holder 1 is oscillated irregularly vertically and horizontally as indicated by the one-dot chain line and the two-dot chain line, thereby converging the incident light L on the recording surface Da of the disk D at a predetermined condensing angle α. It takes a long time, and reading may be delayed or a reading error may occur.

Moreover, as shown in FIG. 6, the square-shaped edge part 1b which supports the objective lens OL of the lens holder 1 is shown.
And the opening 9 of the act cover 8 are formed with gaps β1 and β2, and in particular, the gap β1 is set large in order to freely swing the lens holder 1 in the tracking directions c and d. . Therefore, when the lens holder 1 is swung in the tracking directions c and d, the outer peripheral portion of the parallel light beam C of the incident light L entering the objective lens OL from the collimator lens QWP is spaced from the outside of the square-shaped edge 1b. Since it may pass through β1 and β2 and enter the recording surface Da of the disk D, and the reflected light is unnecessary light, an error such as a reading error occurs when the unnecessary light is received by the light receiving element. Let

An object of the present invention is to provide an objective lens unit that stabilizes sliding and swinging of a lens holder and cuts unnecessary light with a simple structure in view of the above-described conventional drawbacks.

In order to achieve the above object, according to the first aspect of the present invention, an objective lens is provided at the front part of the lens holder, and a focus coil and a tracking coil are provided from the center part to the rear part of the lens holder. By fitting a shaft hole penetrating almost the center of the holder into the shaft of the act base, the weight balance between the front part and the rear part of the lens holder is substantially balanced with the shaft center of the shaft as a fulcrum. By exciting the focus coil and tracking coil, the lens holder is slid in the focus direction along the shaft and swung in the tracking direction around the shaft, and enters the objective lens through the collimator lens. The light is focused on the recording surface of the disk at a predetermined light collection angle,
In the objective lens unit configured to read information recorded on the recording surface by the reflected light, a weight that makes the front part heavier than the rear part is added to the front part of the lens holder. A pair of left and right wings integrally extending along the tracking direction from the left and right side edges of the B-shaped edge surrounding the objective lens, and along the direction orthogonal to the tracking direction from the front and rear side edges of the R-shaped edge A pair of front and rear shelves integrally projecting, and the interval between the two wings is set larger than the sum of the outer diameter of the parallel light flux passing through the collimator lens and the maximum oscillation width of the objective lens, The act cover that covers the lens holder is attached to the act base at a position slightly higher than the highest position of the objective lens, and is larger than the objective lens at a position facing the objective lens of the act cover. Are formed, and the peripheral edge of the opening and the wings and the shelves overlap each other at a predetermined interval in the vertical direction, and the wings overlap the left and right peripheral edges of the opening. The wrap width is set to be larger than one half of the maximum swing width.

According to the second aspect of the present invention, an objective lens is provided at the front part of the lens holder, and a focus coil and a tracking coil are provided from the center part to the rear part of the lens holder. By fitting the provided shaft hole to the shaft of the act base, the weight balance between the front part and the rear part of the lens holder is substantially balanced with the shaft center of the shaft as a fulcrum. By exciting the tracking coil, the lens holder is slid in the focus direction along the shaft and swung in the tracking direction around the shaft, and the incident light that has entered the objective lens through the collimator lens has a predetermined converging angle. To converge on the recording surface of the disc and read the information recorded on the recording surface by the reflected light. In Unishi was the objective lens unit, the weight of the front portion heavier than the rear to the front of the lens holder are added,該錘is, the lens holder objective lens
A pair of left and right wings integrally extending along the tracking direction from the left and right side edges of the B-shaped edge that surrounds
The distance between the wings is such that the outer diameter of the parallel light flux passing through the collimator lens and the objective
It is characterized in that it is set larger than the sum of the maximum oscillation width of the lens .

According to a third aspect of the present invention, in the second aspect of the present invention, the lens holder is covered.
The cover is attached to the Act Base at a position slightly higher than the highest position of the objective lens
In addition, the act cover has a larger diameter than the objective lens at a position facing the objective lens.
An opening is formed, and the left and right peripheral edges of the opening and the wings are spaced apart from each other at a predetermined interval.
The overlap width is larger than half of the maximum swinging width.
It is characterized by being set .

According to a fourth aspect of the present invention, in the invention of the third aspect, the weight is the rounded edge portion.
A pair of front and rear shelves integrally projecting from the front and rear side edges along a direction orthogonal to the tracking direction
Each shelf portion and the front and rear peripheral edge portions of the opening portion of the act cover are vertically spaced apart from each other by a predetermined distance.
It is characterized by being overlapped with each other .

The invention according to claim 1 corresponds to one embodiment (see FIGS. 1 to 5), and according to this, a weight is added to the front part of the lens holder, and the front part is moved from the rear part. Since the upper end of the shaft hole and the front end of the lower end are always in contact with the outer peripheral surface of the shaft, the lens holder is slid in the focus direction or swung in the tracking direction. Thus, unlike the conventional case, the lens holder is not oscillated irregularly vertically and horizontally, and the sliding and swinging of the lens holder is stabilized. Therefore, the incident light can be quickly converged on the recording surface of the disk at a predetermined converging angle, and the information recorded on the recording surface can be instantaneously read without error.

In addition, unnecessary light that passes toward the disk without entering the objective lens at the outer peripheral portion of the parallel light beam incident from the collimator lens is blocked by the both wings of the weight, so that the unnecessary light is blocked on the recording surface of the disk. The light is not reflected and received by the light receiving element, and errors such as reading errors due to unnecessary light can be prevented from occurring.

What is important here is that by simply extending the pair of left and right wings as weights integrally with the front part of the lens holder, the sliding and swinging of the lens holder can be stabilized and unnecessary light can be blocked. This means that the number of parts does not increase and is economical.

In addition, the pair of left and right wings and the pair of front and rear shelves overlap with the peripheral edge of the opening of the act cover, and unnecessary light does not leak outside through the opening. It is possible to reliably prevent such errors.

According to the invention described in claim 2, the outside of the parallel luminous flux incident from the collimator lens
Unnecessary light passing toward the disk without entering the objective lens at the periphery is blocked by both wings of the weight
Therefore, the unnecessary light is not reflected by the recording surface of the disc and received by the light receiving element.
Therefore, it is possible to prevent an error such as a reading error due to the unnecessary light.

What is important here is that a pair of left and right wings as weights are integrally extended to the front part of the lens holder.
It was possible to stabilize the sliding and swinging of the lens holder and to block unnecessary light.
In other words, the number of parts does not increase and the cost is excellent.

According to the third aspect of the present invention, even when the lens holder is swung to the maximum along the tracking direction, the wings and the act cover are overlapped with each other, and unnecessary light is externally transmitted between them. Therefore, it is possible to reliably prevent errors such as reading errors due to unnecessary light.

According to the fourth aspect of the present invention, the pair of front and rear shelves integrally projecting along the direction orthogonal to the tracking direction from the front and rear side edges of the square-shaped edge that surrounds the objective lens and the act cover are over each other. Since unnecessary light does not leak outside between the two, errors such as reading errors caused by unnecessary light can be more reliably prevented.

FIGS. 1 to 5 show an objective lens unit according to an embodiment of the present invention. As shown in FIG. 4B, a rectangular edge 1b surrounding the objective lens OL of the lens holder 1 is shown. A pair of left and right wings 16A, 16B integrally extending from the left and right side edges 16a, 16b by a predetermined protrusion width g1 along the tracking directions c, d, as shown in FIG. A plan view including a pair of front and rear shelves 16C and 16D integrally projecting by a predetermined projecting width g2 along a direction orthogonal to the tracking directions c and d from the front and rear side edges 16c and 16d of the edge 1b. A substantially square-shaped weight 16 is added to the front portion 1A of the lens holder 1 to make the front portion 1A heavier than the rear portion 1B (see FIG. 3). Since the configuration other than the above is substantially the same as the configuration shown in FIGS. 6 to 9, the same reference numerals are given to the same portions and the description thereof is omitted.

4A, the weight 16 is added to the front portion 1A of the lens holder 1 so that the front portion 1A is heavier than the rear portion 1B, so that the upper end edge of the shaft hole 2 can be obtained. Since the rear portion 2a and the lower end edge front portion 2b are always in contact with the outer peripheral surface of the shaft 4, when the lens holder 1 is slid in the focus directions a and b or swung in the tracking directions c and d, The lens holder 1 is prevented from being irregularly oscillated vertically and horizontally as in the prior art, and the lens holder 1
The sliding and swinging of the is stable. Accordingly, the recording surface D of the disk D is incident on the incident light L at a predetermined condensing angle α.
The information recorded on the recording surface Da can be instantaneously read without error by quickly converging to a.

As shown in FIGS. 4B and 5, the distance e between the wing parts 16 </ b> A and 16 </ b> B of the weight 16 is
The outer diameter m of the parallel light beam C passing through the collimator lens QWP and the maximum oscillation width k of the objective lens OL
(E> m + k).

According to the above configuration, when the lens holder 1 is swung in the tracking directions c and d, the outer peripheral portion of the parallel light beam C incident from the collimator lens QWP does not enter the objective lens OL and faces the disk D. Since unnecessary light passing therethrough is blocked by both wing portions 16A and 16B of the weight 16, the unnecessary light is not reflected by the recording surface Da of the disk D and received by the light receiving element, and reading errors due to the unnecessary light, etc. The error can be prevented.

What is important here is that the pair of left and right wings 16A and 16B as the weight 16 is attached to the lens holder 1.
This means that it was possible to stabilize the sliding and swinging of the lens holder 1 and to block unnecessary light by simply extending it integrally with the front part 1A of the lens. Are better.

As an example of specific dimensions, as shown in FIG. 5, when the focal length f is 2 mm, the outer diameter m of the parallel light beam C is 4.8 mm, and the maximum oscillation width k of the objective lens OL is 1.9 mm, Part 16A,
The interval e between 16B is 4.8 + 1.9 = 6.7 mm or more.

As shown in FIGS. 4A and 4B, the top plate portion 8b of the act cover 8 is disposed at a position higher than the most elevated position of the objective lens OL with a slight interval h, and the opening of the act cover 8 is opened. Part 9
And the wings 16A and 16B and the shelves 16C and 16D are overlapped with each other at a predetermined interval in the vertical direction.
The overlap width t1 between A and 16B and the left and right peripheral edge portions of the opening 9 is set to be larger than one half of the maximum swing width k of the objective lens OL (t1> 1 / 2k). In FIG. 4A, reference numeral 18 denotes a substantially cross-shaped stopper portion that is integrally provided on the lower surface of the top plate portion 8 b of the act cover 8 and abuts or approaches the top surface of the shaft 4.

According to the above configuration, the pair of left and right wing parts 16A and 16B and the pair of front and rear shelf parts 16C and 16D.
And the peripheral edge of the opening 9 of the act cover 8 are overlapped, and unnecessary light does not leak to the outside from the opening 9, so that errors such as reading errors due to unnecessary light can be reliably prevented. it can.

By mounting the above-described objective lens unit on a disk device such as a DVD player or a DVD recorder, it is possible to provide a disk device that is economical and easy to use with few errors such as reading errors.

It is a top view of the objective lens unit which is one Embodiment of this invention. It is an AA arrow line view of FIG. It is a disassembled perspective view of the principal part. (A) is the same schematic side view, (b) is a BB arrow line view. It is a schematic enlarged view explaining operation | movement of the objective lens. It is a top view of a prior art example. It is CC arrow line view of FIG. It is a disassembled perspective view of the principal part. (A) is the schematic side view, (b) is an EE arrow view.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Lens holder 1A Front part of a lens holder 1B Rear part of a lens holder 1b B-shaped edge part 3 Act base 4 Shaft 5 Focus coil 6 Tracking coil 8 Act cover 9 Opening part 16a, 16b Left and right side edges 16c , 16d Front and rear edges of the B-shaped edge 16A, 16B Wings 16C, 16D Shelf OL Objective lens QWP Collimator lens α Condensing angle L Incident light C Parallel light beam D Disc Da Disc recording surface e Space between both wings m The outer diameter of the parallel light beam k The maximum oscillation width of the objective lens t1 The overlap width between the opening and both wings t2 The overlap width between the opening and both shelves a, b Focus direction c, d Tracking direction

Claims (4)

An objective lens is provided at the front part of the lens holder, and a focus coil and a tracking coil are provided from the central part to the rear part of the lens holder, and a shaft hole penetrating substantially at the central part of the lens holder has an act base shaft. Is formed so that the weight balance between the front portion and the rear portion of the lens holder is substantially balanced with the shaft center as a fulcrum, by exciting the focus coil and tracking coil,
Slide the lens holder in the focus direction along the shaft and swing it in the tracking direction around the shaft to converge the incident light that has entered the objective lens through the collimator lens onto the recording surface of the disc at a predetermined condensing angle. In the objective lens unit that reads the information recorded on the recording surface by the reflected light, a weight that makes the front part heavier than the rear part is added to the front part of the lens holder. A pair of left and right wings integrally extending along the tracking direction from the left and right side edges of the B-shaped edge that surrounds the objective lens, and from the front and rear side edges of the R-shaped edge in a direction orthogonal to the tracking direction A pair of front and rear shelves integrally projecting along the gap, and the distance between the two wings is greater than the sum of the outer diameter of the parallel light flux passing through the collimator lens and the maximum oscillation width of the objective lens. The act cover that is set and covers the lens holder is attached to the act base at a position slightly higher than the highest rising position of the objective lens, and has a larger diameter than the objective lens at a position facing the objective lens of the act cover. An opening is formed,
The peripheral edge of the opening and the wings and the shelves overlap each other at a predetermined interval in the vertical direction, and the overlap width between the wings and the left and right peripheral edges of the opening is the maximum swing. Width 2
An objective lens unit, wherein the objective lens unit is set to be larger than one part. An objective lens is provided at the front part of the lens holder, and a focus coil and a tracking coil are provided from the central part to the rear part of the lens holder, and a shaft hole penetrating substantially at the central part of the lens holder has an act base shaft. Is formed so that the weight balance between the front portion and the rear portion of the lens holder is substantially balanced with the shaft center as a fulcrum, by exciting the focus coil and tracking coil,
Slide the lens holder in the focus direction along the shaft and swing it in the tracking direction around the shaft to converge the incident light that has entered the objective lens through the collimator lens onto the recording surface of the disc at a predetermined condensing angle. In the objective lens unit that reads the information recorded on the recording surface by the reflected light, the front part is arranged at the front part of the lens holder .
A weight that adds weight is added, and these weights are located on the left and right sides of the square-shaped edge that surrounds the objective lens of the lens holder.
A pair of left and right wings integrally extended from the side edge along the tracking direction, the wings
Is the sum of the outer diameter of the parallel light flux passing through the collimator lens and the maximum oscillation width of the objective lens.
Objective lens unit characterized in that it is set larger than The act cover that covers the lens holder is slightly higher than the highest position of the objective lens.
Position on the act base and facing the objective lens of the act cover
An opening having a diameter larger than that of the objective lens is formed on the left and right edges of the opening and the wings.
They overlap each other at a predetermined interval in the vertical direction, and the overlap width is the maximum swing.
The objective lens unit according to claim 2, wherein the objective lens unit is set to be larger than a half of the moving width . The weight extends along the direction orthogonal to the tracking direction from the front and rear side edges of the square-shaped edge.
It is equipped with a pair of front and rear shelves projecting integrally, and front and rear of each shelf and the opening of the act cover
The objective lens unit according to claim 3, wherein the peripheral portion overlaps each other at a predetermined interval in the vertical direction .

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