JPH04310632A - Pick-up lens fitting structure - Google Patents

Abstract

PURPOSE:To easily adjust the inclination of a pick-up lens by providing a taper member to form a taper surface in an inner surface at the lens fitting hole of a lens holder and forming radiused shape part at the abutting surface of the pick-up lens to abut to the taper member. CONSTITUTION:At a lens fitting hole 31 of a lens holder 30, a taper member 34, in which the inner surface is the taper surface, is provided, and radiused shape part 33 is formed at the abutting surface of a pick-up lens 32 to abut to the member 34. Thus, the inclination of the pick-up lens 32 is adjusted by turning the lens 32 in the taper member 34 with the central point of the radiused shape part 33 of the lens 32 as a center. After the inclination adjustment of the pick-up lens 32 is completed, the lens 32 is fixed to the taper member 34 with adhesives, etc.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to an optical pickup device that reads a signal by irradiating an optical disc with a laser beam from a pickup lens, and particularly relates to a pickup lens mounting structure for mounting a pickup lens into a lens fitting hole of a lens holder. It is related to.

0002

[Prior Art] Optical disc playback devices generally read signals by shining a laser beam onto the recording surface of the optical disc while rotating the optical disc. Demand for optical disc playback devices has increased because high-quality signals can be played back. ing. Therefore,
In recent years, various types of optical disc playback devices have been manufactured and sold, but drive devices that drive the disc at a constant rotation speed, optical pickup devices that read signals by shining a laser beam on the recording surface of the disc, etc. It is an essential part of the device, and a device with excellent productivity is desired.

In particular, the optical pickup device is an important part that controls signal reading, and many improvements have been made over the past. FIG. 6 shows a conceptual diagram of a general optical pickup device.

That is, the pickup lens 3 is held by the actuator 2 and is disposed facing the recording surface of the disk 1. A prism 4 is provided below the pickup lens 3 in the vertical direction, and on the horizontal right side of the prism 4 in the figure, a collimator lens 5, a beam splitter 6, a correction plate 7, a concave lens 8, and a light receiving element 9 are provided. arranged in a straight line. Further, below the beam splitter 6 in the vertical direction, a diffraction grating 10 and a light emitting element 11 that emits laser light are sequentially installed.

The laser light path of the optical pickup device having such a configuration is as follows. First, the light emitting element 11
The laser beam emitted from the laser beam passes through the diffraction grating 10 and enters the beam splitter 6, where it is directed 90 degrees to the left in the figure.
bend many times. Further, the laser beam passes through the collimator lens 5, enters the prism 4, is bent 90 degrees upward in the figure, and enters the pickup lens 3. Here, the pickup lens 3 forms an image of the laser beam and irradiates it onto the recording surface 1a of the disk 1. The laser beam irradiated onto the recording surface 1a is reflected by the recording surface 1a toward the pickup lens 3 side.

Furthermore, the laser beam reflected by the recording surface 1a of the disk 1 passes through a pickup lens 3 and is bent in a right angle direction by a prism 4. The bent laser beam passes through a collimator lens 5, a beam splitter 6, and a correction plate 7.
, passes through the concave lens 8, and is received by the light receiving element 9.

By the way, tracks are formed on the recording surface 1a of the disk 1 by hole-shaped marks arranged spirally from the center toward the periphery. Signals are recorded based on the length and spacing of these marks. When the recording surface 1a of such a disc 1 is irradiated with laser light, the amount of reflected laser light changes depending on the presence or absence of marks.

That is, as shown in FIG.
On the recording surface 1a, the amount of light a reflected by a flat portion f where there is no mark m is approximately the same amount of light as the irradiated laser beam, and is reflected toward the pickup lens 3 side. On the other hand, as shown in FIG. 8, the amount of light b reflected by mark m is due to the fact that the reflected light also hits the inner peripheral surface of mark m.
The amount of light reflected to the pickup lens 3 side is smaller than the light amount a.

Using the above, the signal recorded on the recording surface 1a is converted into two types of optical signals, and these optical signals are read as digital signals.

By the way, each member numbered 4 to 11 in FIG. 6 is integrally fixed to the main body side of the optical pickup device. On the other hand, in order to perform stable recording and reproduction, the pickup lens 3 is controlled by the actuator 2 in the focusing direction (z direction in FIG. 6) and the tracking direction (in the z direction in FIG. 6).
It is attached to the main body side of the optical pickup device so as to be movable in the x direction).

The pickup lens 3 is aligned in the focus direction (
The functions of moving in the vertical direction) and the tracking direction (horizontal direction) are generally called a focus servo function and a tracking servo function. By using these focus servo functions and tracking servo functions,
The pickup lens 3 located at the focal position does not generate coma aberration, and exhibits excellent visual field characteristics to realize ideal imaging. When attaching the pickup lens 3 having such a function to an optical pickup device, the following two things are required.

One is that the pickup lens 3 is located on the recording surface 1a.
The other is that the spot of the laser beam from the pickup lens 3 is irradiated onto the ideal center position of the recording surface 1a.

However, the pickup lens 3 is tilted or misaligned with respect to the optical axis of the laser beam due to cumulative assembly errors. Therefore, when attaching the pickup lens 3 to the main body of the optical pickup device, two parts are required: one for adjusting the inclination of the pickup lens 3 and the other for adjusting the center of the laser beam spot. For this reason, a pickup lens mounting structure having the above-mentioned two adjustment parts has been proposed. Here, a conventional example of a pickup lens mounting structure will be described with reference to FIGS. 9 and 10.

As shown in FIGS. 9 and 10, the base 14 installed on the main body side of the optical pickup device has an R-shaped recess 14a.
A prism 4 is arranged in the center of the . A pickup lens 3 adhesively fixed to a lens fitting hole 31 of a lens holder 30 is arranged above the prism 4. Further, the skew plate 12 is fixed to the upper surface of the base 14 by screws 13 to which springs 15 are attached.

This skew plate 12 has a base 14.
A spherical seat 12a is formed along the shape of the recess 14a, and on the left and right sides of the spherical seat 12a on the upper surface of the skew plate 12,
A support plate 17 is fixed. Support plate 17
A through hole 17a is formed at the base of the holder, into which a fixing screw 16 is inserted. In addition, support plate 1
A horizontal adjustment allowance is formed in the through hole 17a of No. 7, and the screw 16 slides thereon.

The upper part of the support plate 17 has substantially U-shaped opposing surfaces, and a magnet 20 is provided inside the outer surface. On the other hand, focus coils 18 are installed on the left and right sides of the inner side surface. A tracking coil 19 is installed at a position of the focus coil 18 facing the magnet 20. The focus coil 18 described above is for moving the lens holder 30 in the focusing direction, and the tracking coil 19 is for moving the lens holder 30 in the tracking direction.

In the pickup lens mounting structure having the above configuration, the tilt adjustment of the pickup lens 3 and the spot adjustment of the laser beam are performed as follows.

First, the inclination of the pickup lens 3 is determined by the spherical seat 1 of the skew plate 12 in the recess 14a of the base 14.
2a and rotate the ball seat 12a into the recess 14a to adjust the inclination of the skew plate 12, and when the adjustment is completed, it is fixed to the base 14 with the screws 13. At this time, the spring 15 adjusts the force balance.

On the other hand, the spot adjustment of the laser beam is performed using the adjustment clearance formed in the through hole 17a of the support plate 17, and when the adjustment is completed, it is fixed to the skew plate 12 with the screw 16. .

[0020]

However, the above conventional example has the following problems. That is, it is difficult to precisely machine the recess 14a of the base 14 and the spherical seat 12a of the skew plate 12 that abuts thereon. At this time, since the two members described above are members for adjusting the inclination of the pickup lens 3, their processing accuracy directly affects the adjustment accuracy. Further, since the support plate 17 that performs spot adjustment of the laser beam is fixed on the skew plate 12, it is deeply related to the adjustment accuracy of the skew plate 12.

As a result, if the machining accuracy of the recess 14a of the base 14 and the spherical seat 12a of the skew plate 12 is increased, production costs will increase. On the other hand, if priority is given to reducing production costs, the accuracy of the tilt adjustment of the pickup lens 3 and the spot adjustment of the laser beam will deteriorate.

In addition to the above-mentioned problems, there are also problems with the skew plate 12 itself. That is, the spherical seat 12a
It is difficult to completely fix the skew plate 12 with the screws 13 to the base 14, and there is a high possibility that the skew plate 12 will shift due to changes in the environment. If the skew plate 12 is displaced, naturally the support plate 17 installed on the skew plate 12 is also displaced. This caused problems such as the pickup lens 3 being tilted and the laser beam spot being shifted from the ideal center position.

The present invention was proposed to solve the above-mentioned problems, and its purpose is to provide a structure with a simple structure, easy adjustment work, high adjustment accuracy, and excellent resistance to environmental changes. It is an object of the present invention to provide a pickup lens mounting structure.

[0024]

[Means for Solving the Problems] In order to solve the above problems, the pickup lens mounting structure of the present invention includes a tapered member having a tapered inner surface in the lens fitting hole of the lens holder. A structural feature is that an R-shaped portion is formed on the abutting surface of the pickup lens that abuts the member.

[0025] Furthermore, the present invention provides an R
It is characterized in that the center point of the shaped portion is located at the second principal point of the pickup lens. Generally, there are two principal points on the optical axis that passes through the pickup lens, the first principal point is the point located on the entrance side of the laser beam from the light source, and the first principal point is the point located on the exit side of the laser beam. 2 principal points.

[0026]

[Operation] In the present invention having the above structure, the inclination of the pickup lens is adjusted by rotating the pickup lens within the tapered member about the center point of the rounded portion of the pickup lens. After the tilt adjustment of the pickup lens is completed, the pickup lens is fixed to the tapered member using an adhesive or the like.

Furthermore, since the present invention does not require members that are difficult to process, such as a spherical seat formed on the skew plate,
The configuration becomes simple and cumulative errors are reduced. Therefore,
It is also possible to manage the spot adjustment of the laser beam only within the allowable range of the dimensional accuracy of the member.

Moreover, in the present invention, since the center point of the R-shaped portion is located at the second principal point of the pickup lens, even if the pickup lens is rotated, the center point of the R-shaped portion is the second principal point of the pickup lens. The principal point does not move. Therefore, the spot of the laser beam also does not move, and spot adjustment becomes unnecessary.

However, in practice, it may be necessary to adjust the spot of the laser beam. In this case, set a predetermined adjustment allowance in the lens holder so that the taper member can move horizontally within the lens holder, and adjust the spot of the laser beam by moving the pickup lens horizontally together with the taper member. Can be done. When such spot adjustment of the laser beam is completed, the tapered member is fixed to the lens holder with an adhesive or the like.

[0030]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the pickup lens mounting structure of the present invention as described above will be described with reference to the drawings. A first embodiment is shown in FIGS. 1 and 2, and a second embodiment is shown in FIGS. 3 to 5.

[0031] Regarding the same members as those in the prior art,
The same part number will be given and the explanation will be omitted.

(First Embodiment) As shown in FIG. 1, a rectangular hole-shaped recess 14b is formed in the base 14.
A prism 4 is arranged here. Also, base 14
The support plate 17 is attached to the screw 1 on the left and right sides of the recess 14b on the top surface.
It is directly fixed by 6.

Incidentally, a pickup lens 32 is disposed above the prism 4 and is installed in a lens fitting hole 31 of a lens holder 30. A tapered member 34 having a tapered inner surface is provided in the gap between the pickup lens 32 and the lens fitting hole 31.

Further, the pickup lens 3 is attached to the outer peripheral surface of the pickup lens 32 that comes into contact with the tapered member 34.
A shaped portion 33 that forms a spherical surface with a radius R centered on the second principal point H2 of No. 2 is formed. Note that the second principal point H2 is a principal point located on the exit side of the laser beam from the light emitting element that is the light source in the pickup lens 32.

Furthermore, as shown in FIG. 2, the tapered member 3
A stepped portion 34a is formed on the outer periphery of the lens 4, and this stepped portion 34a is placed on the stepped portion 30a on the lens holder 30 side. At this time, an adjustment allowance d is set so that the taper member 34 can move horizontally into the lens holder 30.

In the first embodiment having the above configuration, the tilt adjustment of the pickup lens 32 and the laser beam spot adjustment are performed as follows.

First, the inclination of the pickup lens 32 is
The pickup lens 32 is rotated within the tapered member 34 around the second principal point H2, which is the center point of the rounded portion 33. Then, the laser beam spot is adjusted while being viewed from above with a microscope or the like (not shown). When the tilt adjustment of the pickup lens 32 is completed, adhesive is injected into the gap between the pickup lens 32 and the tapered member 34, and the pickup lens 32 is fixed.

Further, in this embodiment, the spherical seat 12a formed on the skew plate 12 and the R-shaped recess 14 on the base 14
Since no parts such as a are provided, there is little deviation due to accumulation of members, and the spot adjustment of the laser beam can be controlled within an allowable range with the accuracy of the members.

Moreover, in the present invention, the R-shaped portion 33
The center point of is located at the second principal point H2 of the pickup lens 32. Therefore, even if the pickup lens 32 is rotated, the second principal point H2 of the pickup lens 32 will not be displaced. Therefore, the spot of the laser beam also does not shift, and spot adjustment becomes unnecessary.

If it becomes necessary to adjust the laser beam spot, the adjustment can be performed by moving the taper member 34 horizontally within the adjustment margin d while viewing the laser beam spot from above on a monitor or the like. Then, when the spot adjustment of the laser beam is completed, adhesive is injected into the gap between the taper member 34 and the lens holder 30, and the taper member 34 is fixed.

As described above, this embodiment does not require any members that are difficult to process and has a simple configuration, which not only makes it possible to reduce production costs, but also reduces cumulative errors during assembly. , the amount of adjustment is small, and workability is improved. Furthermore, since the center of the R-shaped portion 33 is set at the second principal point H2 of the pickup lens 32, the spot of the laser beam does not shift even if the pickup lens 32 rotates. Therefore, even if some vibration is applied to the pickup lens 32, the spot of the laser beam is unlikely to shift, and environmental resistance is greatly improved.

(Second Embodiment) By the way, in the second embodiment,
In this embodiment, the pickup lens 32, taper member 34, and lens holder 30 of the first embodiment are covered with a substantially donut-shaped adhesive film 35 as shown in FIG. The adhesive film 35 is made of a thin film that has plasticity, such as aluminum foil, and maintains its shape after deformation. Also,
Injection holes 35a are formed in the adhesive film 35 at positions facing each other so as to inject adhesive into the gap between the pickup lens 32 and the tapered member 34, and there is only one injection hole 35a on the periphery.
An outwardly extending tongue portion 35b is formed.

Further, as shown in FIG. 4, the adhesive film 35 has an adhesive applied to its back surface and is pasted onto the upper surfaces of the pickup lens 32 and the tapered member 34. Further, the tongue portion 35b of the adhesive film 35 is set to reach the lens holder 30 with a mountain-shaped bulge portion 35c.

The operation of the second embodiment having the above structure is as follows.

First, an adhesive is applied to the back surface of the adhesive film 35, and the film is horizontally attached to the upper surfaces of the pickup lens 32 and the tapered member 34, as shown in FIG. Thereafter, similarly to the first embodiment, the pickup lens 32 is rotated into the tapered member 34 to adjust the inclination. At this time, as shown in FIG. 5, the adhesive film 35 deforms according to the inclination of the pickup lens 32 and maintains its shape. Therefore, the adhesive film 35 maintains its shape and maintains the positions of the pickup lens 32 and the tapered member 34 when the tilt adjustment is completed. Furthermore, the adhesive is picked up from the injection hole 35a through the lens 3.
2 and the taper member 34. The pickup lens 32 is held by the adhesive film 35 until the adhesive hardens.
Since the and taper member 34 are fixed, they will not shift due to vibration or the like.

The pickup lens 32 is the tapered member 3
4, the laser beam spot is adjusted. By the way, the lens holder 30 and the taper member 34 are stuck together only by the tongue portion 35b of the adhesive film 35. Therefore, the taper member 34 can freely move in the horizontal direction by 360 degrees, except in the direction opposite to the direction in which the tongue portion 35b extends (direction of arrow a in FIG. 4). Further, since the tongue portion 35b has a slack portion 35c, the mountain-shaped slack portion 35
By flattening c, the tapered member 34 can be moved in the direction of arrow a.

Further, when the spot adjustment of the laser beam is completed, the adhesive film 35 maintains its shape, and the tongue portion 35b maintains the position of the tapered member 34 and the lens holder 30. Finally, adhesive is injected through the gap between the tapered member 34 and the lens holder 30. Until the adhesive hardens,
Since the tongue portion 35b is stuck to the lens holder 30, the taper member 34 and the lens holder 30 will not be inadvertently displaced. In addition, the lens holder 30 and the taper member 3
Even if the adhesive film 35 is applied to the upper surface of the tapered member 4, the horizontal movement of the tapered member 34 is not hindered, and the spot adjustment of the laser beam can be performed appropriately.

According to the second embodiment as described above, in addition to the same effects as the first embodiment, the pickup lens 3 and the tapered member 34 are Since it is fixed by the adhesive film 35, even if the member is lightweight, it is difficult to shift, and workability is further improved. Furthermore, when the pickup lens 3, the tapered member 34, and the lens holder 30 are bonded with adhesive, there is no need for a large-scale jig to fix each member to each other until the adhesive is completely dry. Therefore, the production equipment is simplified and excellent mass productivity can be achieved.

It should be noted that the present invention is not limited to the above two embodiments, and the shape and dimensions of each member can be changed as appropriate, and the material of the adhesive film covering the pickup lens and tapered member can be changed. It can be selected as appropriate.

[0050]

As described above, according to the pickup lens mounting structure of the present invention, the pickup has a tapered member disposed in the lens fitting hole of the lens holder with an R-shaped portion formed on the outer peripheral surface. The tilt of the pickup lens can be adjusted by simply rotating the lens.

[0051] Furthermore, since the configuration is simple, cumulative errors are small, and even if the adjustment accuracy is increased, it is easy to realize cost reduction. Therefore, excellent mass productivity can be ensured, and this can greatly contribute to improving the productivity of optical pickup devices.

Furthermore, since the center point of the R-shaped portion is located at the second principal point of the pickup lens, even if the pickup lens rotates, the second principal point of the pickup lens, which is the center point of the R-shaped portion, does not move. The laser beam spot will not shift. Therefore, it can exhibit strength against environmental changes such as vibration.

[Brief explanation of drawings]

FIG. 1 is a front view of a first embodiment of a pickup lens mounting structure of the present invention.

FIG. 2 is a front view of main parts of the first embodiment.

FIG. 3 is a plan view of an adhesive film used in a second embodiment.

FIG. 4 is a front view of main parts showing the start of adjustment work in the second embodiment.

FIG. 5 is a front view of main parts showing the end of adjustment work in the second embodiment.

FIG. 6 is a conceptual diagram of a general optical pickup device.

FIG. 7 is a front view showing a laser beam emitted from a pickup lens and a laser beam reflected on a flat portion of a disk recording surface in a general optical pickup device.

FIG. 8 is a front view showing a laser beam emitted from a pickup lens and a laser beam reflected on a mark portion of a disk recording surface in a general optical pickup device.

FIG. 9 is a front view of a conventional pickup lens mounting structure.

FIG. 10 is an exploded perspective view of a conventional pickup lens mounting structure.

[Explanation of symbols]

1 Disc 2 Actuator 3 Pickup lens 4 Prism 5 Collimator lens 6 Beam splitter 7 Correction plate 8 Concave lens 6 9 Photo receiving element 10 Diffraction grating 11 Light emitting element 12 Skew plate 12a Baseball 13 Screw 14 Base 15 Spring 16 screw 17 Support plate 18 Focus coil 19 Tracking coil 20 Magnet 30 Lens holder 31 Lens fitting hole 32 Pickup lens 33 R-shaped part 34 Taper member 35 Adhesive film 35a Injection hole 35b Tongue 35c Clear area H2 2nd principal point

Claims (2)

[Claims] 1. A pickup lens mounting structure in which a pickup lens for irradiating an optical disk with a laser beam emitted from a light source is mounted in a lens fitting hole of a lens holder, wherein the lens fitting hole of the lens holder has a tapered inner surface. A pickup lens mounting structure characterized in that a tapered member is disposed, and an R-shaped portion is formed on a contact surface of the pickup lens that contacts the tapered member. 2. The center point of the rounded portion is located at the second principal point of the pickup lens located on the exit side of the laser beam from the light source.
Pickup lens mounting structure described in section.