JPH0515120U - Pickup lens mounting structure - Google Patents

Abstract

(57) [Abstract] [Purpose] A simple structure is adopted to simplify the adjustment work, improve the adjustment accuracy, and improve the productivity. [Structure] The center point O of the recess 20a of the base 20 is set as the second principal point H ₂ of the pickup lens 30.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a pick-up lens mounting structure for mounting a pickup lens on a main body side of an optical pickup device, and particularly, an arrangement of constituent members is improved.

[0002]

[Prior Art]

 In general, an optical disk reproducing apparatus reads a signal by irradiating a recording surface of the optical disk with a laser beam while rotating the optical disk, and a reproduced signal of high quality can be obtained, so that the demand is increasing. Therefore, in recent years, various types of optical disk reproducing devices have been manufactured and sold.

With such diversification of the optical disc reproducing apparatus, the optical pickup device which controls the reading of the disc signal is an indispensable main component of the device, and therefore, the improvement of productivity and performance is required. However, many improvements have been added over the past.

Here, FIG. 4 shows a conceptual diagram of a general optical pickup device.

That is, the pickup lens 3 is held by the actuator 2 and arranged so as to face the recording surface 1 a of the disc 1. A prism 4 is provided below the pickup lens 3 in the vertical direction, and a collimator lens 5, a beam splitter 6, a correction plate 7, a concave lens 8, and a light receiving element 9 are provided on the right side of the prism 4 in the horizontal direction. Are arranged on 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. At this time, the optical axis L1 which is the central axis of the laser light emitted from the light emitting element 11 through the prism 4 toward the disc 1 is set to the ideal central position on the recording surface 1a. There is.

The laser optical path of the optical pickup device having such a configuration is as follows. First, the laser light emitted from the light emitting element 11 passes through the diffraction grating 10 and is incident on the beam splitter 6, and is bent 90 degrees leftward in the drawing. Further, the laser light is made incident on the prism 4 through the collimator lens 5, is bent 90 degrees upward in the figure, and is made incident on the pickup lens 3. Then, the laser light is imaged by the pickup lens 3, and the spot of the laser light is applied to the recording surface 1 a of the disc 1. Further, the irradiated laser light is reflected by the recording surface 1a toward the pickup lens 3 side.

On the other hand, the laser light reflected on the recording surface 1 a of the disk 1 passes through the pickup lens 3 and is bent by the prism 4 in the right angle direction. The bent laser light passes through the collimator lens 5, the beam splitter 6, the correction plate 7, and the concave lens 8, and is received by the light receiving element 9. At this time, the recording on the recording surface 1a of the disk 1 is read by the change of the light amount of the laser light received by the light receiving element 9.

By the way, the respective members 4 to 11 in FIG. 4 are integrally fixed to the main body side of the optical pickup device. On the other hand, in order to perform stable recording reading, the pickup lens 3 is moved in the focusing direction (z direction in FIG. 4) and the tracking direction (x direction in FIG. 4) by the coil provided in the actuator 2. It is movably mounted on the body side of the optical pickup device.

Generally, the function of moving the pickup lens 3 in the focus direction (vertical direction) and the tracking direction (horizontal direction) is called a focus servo function and a tracking servo function. By using these focus servo function and tracking servo function, the pickup lens 3 can image the spot of the laser light at an ideal position, so that no coma aberration occurs and the visual field characteristics of the lens. Is ensured in the best condition, so that the signal can be reliably read.

In order to make full use of such a function, the following two things are required of the optical pickup device. One is that the pickup lens 3 is not tilted with respect to the recording surface 1a, and the other is that the spot of the laser light emitted from the pickup lens 3 is applied to the ideal center position of the recording surface 1a. is there.

However, the pickup lens 3 is tilted with respect to the recording surface 1a or the spot of the laser light emitted from the pickup lens 3 is ideal on the recording surface 1a due to an accumulated error in assembling. It may shift from the center position. Therefore, a part for adjusting the inclination of the pickup lens 3 and a part for adjusting the spot of the laser light are required. Therefore, conventionally, a pickup lens mounting structure having a portion for performing the above two adjustments has been proposed. A conventional example of such a pick-up lens mounting structure will be described with reference to FIGS. 5, 6 and 10.

As shown in FIGS. 5 and 6, the base 14 installed on the main body side of the optical pickup device is provided with a concave portion 14a recessed in an R shape. As shown in FIG. 10, the concave portion 14 a is a sphere having a radius R from a predetermined center point O located on the optical axis L 1 of the laser light from the prism 4, and the upper side of the portion where the sphere overlaps the base 14. It is formed by hollowing out a half shape into an R shape. The bottom surface of the recess 14a is flat, and the prism 4 described above is arranged in the center of the bottom surface.

As shown in FIGS. 5 and 6, a home base type ski plate 12 is provided on the upper surface of the base 14. At the center of the skew plate 12, a spherical seat 12a whose center point is located on the optical axis L1 is formed along the R shape of the recess 14a of the base 14. It is set by sliding the ball seat 12a in the recess 14a of the base 14. At the end of the skew plate 12 on the center line, a screw 13a to which a spring 15 is attached is arranged. On the other hand, adjustment screws 13b and 13b are provided at the left and right ends of the skew plate 12, and by tightening one of these adjustment screws 13b and 13b, the screw 13a is used as a fulcrum. The skew plate 12 can be rotated.

Further, in the skew plate 12, fixing holes 12b are opened on the left and right of the ball seat 12a, and the support plate 17 is fixed. A through hole 17a is formed at the base of the support plate 17, and a fixing screw 16 that penetrates to the fixing hole 12b of the skew plate 12 is penetrated here. Further, a horizontal adjustment allowance is formed in the through hole 17a of the support plate 17 so that the support plate 17 slides with respect to the screw 16 to move the skew plate 12 left and right. ing.

The pickup lens 3 is fitted and adhered to a lens fitting hole 3b formed in the lens holder 3a.

In the pickup lens mounting structure having the above configuration, the inclination of the pickup lens 3 is such that the ball seat 12a of the skew plate 12 is brought into contact with the recess 14a of the base 14 and the screw 13a to which the spring 15 is attached is attached. With the fulcrum as a fulcrum, the left and right adjusting screws 13b are appropriately tightened to rotate the ball seat 12a into the recess 14a to adjust the inclination of the skew plate 12. At that time, the spring 15 mounted on the screw 13a adjusts the balance of the fixing force.

On the other hand, the spot adjustment of the laser light emitted from the pickup lens 3 to the disc 1 is performed by moving the support plate 17 left and right by using the adjustment allowance formed in the through hole 17 a of the support plate 17. Make adjustments. Then, when the spot adjustment is completed, the support plate 17 is fixed to the skew plate 12 with the screw 16.

[0018]

[Problems to be solved by the device]

 Here, an example of the operation of the pickup lens 3 when adjusting the inclination of the pickup lens 3 and adjusting the spot of the laser light will be specifically described with reference to FIGS. 7 to 10.

In FIGS. 7 to 10, O is the center point of the base 14, H ₁ is the first principal point of the pickup lens 3, and H ₂ is the second principal point of the pickup lens 3. The first principal point and the second principal point are on the optical axis passing through the pickup lens 3, the first principal point is located on the entrance side of the laser light from the light source, and the second principal point is the laser. It is a point located on the light exit side.

Similarly to the optical axis L1 in FIG. 4, L1 is an optical axis at an ideal position irradiated by the prism 4, and L2 and L3 are optical axes from the pickup lens 3 before adjustment. ing.

In the initial state before adjustment shown in FIG. 7, the pickup lens 3 is inclined with respect to the disc 1 in the counterclockwise direction by θ1 degree, and at the same time, the laser light emitted from the pickup lens 3 is changed. The spot on the optical axis L2 is shifted to the left in the figure by Δ1 when viewed from the spot on the optical axis L1. Although not shown, a microscope for observing the spot of the laser light from above the pickup lens 3 and a monitor for observing the tilt of the pickup lens 3 are used as the adjusting machine.

First, spot adjustment is performed on the pickup lens 3 in the initial state as described above. That is, while viewing the microscope, the support plate 17 shown in FIGS. 5 and 6 is moved rightward in the drawing by Δ1. As a result, the pickup lens 3 shifts from the state shown in FIG. 7 to the state shown in FIG. 8, and the spot on the optical axis L2 coincides with the spot on the optical axis L1. Although the spot shift is eliminated by such horizontal adjustment, the pickup lens 3 is still tilted by θ degrees in the counterclockwise direction in the figure, and the optical axis L2 and the optical axis L1 do not coincide.

Therefore, the inclination of the pickup lens 3 is adjusted next. While watching the monitor, the adjusting screw 13b shown in FIGS. 5 and 6 is rotated to rotate the skew plate 12 in the clockwise direction in the figure by θ1 degree. As a result, the pickup lens 3 shifts from the state of FIG. 8 to the state of FIG. By this adjustment, the inclination of the pickup lens 3 with respect to the disc 1 is eliminated. Therefore, the pickup lens 3 can secure excellent visual field characteristics.

However, as the skew plate 12 is rotated, the adjusted spot in the state shown in FIG. 8 is displaced again. That is, in FIG. 9, the spot on the optical axis L3 from the pick-up lens 3 is displaced from the spot on the optical axis L1 by Δ 2 to the right in the figure.

Therefore, this time, the support plate 17 shown in FIGS. 5 and 6 is moved leftward in the drawing by Δ2, and the pickup lens 3 is moved to the position shown in FIG. Therefore, the optical axis L3 and the optical axis L1 are completely coincident with each other, and the spot of the laser light emitted from the pickup lens 3 can hit the ideal center position of the recording surface 1a of the disc 1 and the coma aberration. Occurrence can be prevented.

By the way, in the above adjustment work, when the inclination of the pickup lens 3 is adjusted, the spot position once corrected deviates, so the spot adjustment is performed again. In fact, the optical axis L2 from the pickup lens 3 in the initial state is often deviated from the optical axis L1 from the prism 4, and the first spot adjustment is often a coarse adjustment.

Further, in the above two adjustment operations, particular attention is paid to the tilt adjustment of the pickup lens 3. That is, even if the spot adjustment of the laser light is deviated, if the deviation is within the correction range of the tracking servo function, the deviation can be covered by operating this function. However, the optical pickup device is not provided with a function of correcting the inclination shift of the pickup lens 3 due to the rotation of the skew plate 12. Therefore, high accuracy is required for adjusting the tilt of the pickup lens 3. As a result, the inclination adjustment of the pickup lens 3 has priority over the slight spot deviation, and the number of spot adjustments tends to increase.

As described above, in the conventional example, the spot adjustment is generally performed a plurality of times. Therefore, the work efficiency and the productivity are low, the structure is complicated, and the assembly man-hour and the production cost are increased.

The present invention has been proposed to solve the above problems, and its purpose is to mount a pick-up lens that has a simple structure, high adjustment accuracy, and excellent workability and productivity. To provide the structure.

[0030]

[Means for Solving the Problems]

 In order to solve the above problems, the pickup lens mounting structure of the present invention is provided with a base through which the optical axis of the laser light passes, and the pickup lens is mounted on this base and an adjustable skew plate is mounted. A structural feature is that an R-shaped recess centering on the second principal point of the pickup lens is formed in the center of the, and a spherical seat abutting this recess is provided on the skew plate.

[0031]

[Action]

 In the present invention having the above configuration, since the center point of the R-shaped recess formed in the center of the base is set to the second principal point of the pickup lens, the spherical seat of the skew plate that abuts the recess is formed. The center point is also located at the second principal point of the pickup lens. Since the center point of the ball seat is the center of the rotation of the skew plate, this center point does not move even if the skew plate is arbitrarily rotated when adjusting the tilt of the pickup lens.

Therefore, even if the tilt of the pickup lens is adjusted, the second principal point of the pickup lens does not move. Therefore, the spot deviation of the laser beam hardly occurs, and the spot adjustment of the laser beam, which is conventionally performed plural times, is unnecessary.

Moreover, since it is possible to concentrate only on the tilt adjustment of the pickup lens due to the rotation of the skew plate, it is possible to ensure high adjustment accuracy.

[0034]

【Example】

 An embodiment of the mounting structure of the pickup lens of the present invention as described above will be described with reference to FIGS.

It should be noted that, in the present invention, in the mounting structure of the pickup lens, the arrangement of the constituent members is improved. Therefore, in the present embodiment, basically, the same constituent members as those in the conventional example are adopted, and the description of the members with the same reference numerals and the shapes of the pickup lens and the base having different positional relationships will be omitted.

That is, as shown in FIGS. 1 and 2, an R-shaped recess 20 a having a radius r is formed in the center of the base 20. The center point O of the recess 20a is set to the second principal point H ₂ of the pickup lens 30.

Further, as shown in FIG. 3, the pickup lens 30 is fitted in the lens fitting hole 30b and fixed to the lens holder 30a. Further, the lens holder 30 a is supported by the support portion 23 that is erected on the skew plate 22. The skew plate 22 of this embodiment has a shape in which the support plate 17 of FIG. 5 and the skew plate 12 shown in the conventional example are integrally formed. The skew plate 22 is provided with a ball seat 24 having a shape along the recess 20a of the base 20, as in the conventional example.

Further, the optical axis L1 of the laser light emitted from the prism 4 is set so as to pass through the ideal center position of the recording surface 1a of the disk 1 in advance, as described above. At this time, since the prism 4 is located at the center of the base 20 like the base 14, the center point O of the recess 20a is located on the optical axis L1. Therefore, the second principal point H ₂ of the pickup lens 30 always exists on the optical axis L1 regardless of the inclination of the pickup lens 30. Here, by taking the height dimension of the support portion 23 on the skew plate 12 into consideration, the spot of the laser light emitted from the pickup lens 30 is always at the ideal center position of the recording surface 1a of the disc 1. Can be set to.

Although the pickup lens 30 irradiates the spot of the laser light to the ideal center position of the recording surface 1a of the disc 1 as described above, the pickup lens 30 is applied to the recording surface 1a of the disc 1 due to an assembly error or the like. May tilt. FIG. 1 shows an example of the initial state of the pickup lens 30 before adjustment. Here, the pick-up lens 30 is tilted in the counterclockwise direction in the figure by θ2 degrees with respect to the recording surface 1a of the disk 1.

By the way, if the pickup lens 30 and the base 20 are arranged as described above, it is theoretically possible to keep the deviation of the horizontal component for performing the spot adjustment within the allowable range by controlling the accuracy of each component and the assembly accuracy. Is possible. However, in actual work, some spot adjustment may be necessary. Therefore, as shown in FIG. 3, an adjustment allowance Δd is formed in the lens fitting hole 30b for holding the pickup lens 30 so that the pick-up lens 30 can move horizontally in the lens holder 30a.

In the present embodiment having the above-mentioned configuration, the tilt adjustment of the pickup lens 30 is performed as follows.

That is, by tilting the skew plate 22 in contact with the base 20 by θ2 degrees in the clockwise direction in the figure, the inclination of the pickup lens 30 with respect to the disk 1 is eliminated.

Even if the inclination of the pickup lens is adjusted in this manner, the second principal point H ₂ of the pickup lens 30, which coincides with the center point O of the recess 20 a of the base 20, does not move in the horizontal direction. The spot adjustment of laser light is almost unnecessary.

If the spot adjustment of the laser light is absolutely necessary, this can be done by moving the pickup lens 30 in the horizontal direction within the adjustment allowance Δd formed in the lens fitting hole 30b. it can. Then, when the laser light spot adjustment is completed, an adhesive is injected into the space between the pickup lens 30 and the lens holder 30a to fix the pickup lens 30 to the lens holder 30a.

As described above, according to the pickup lens mounting structure of the present embodiment, since the spot adjustment of the laser light does not shift, it is possible to exert considerable strength against changes in environmental conditions. Further, since the spot adjustment of the laser light is almost unnecessary, the work efficiency is improved and the production cost can be significantly reduced. Moreover, since it is possible to concentrate on the tilt adjustment of the pickup lens 30 which cannot be corrected after the mounting, a high adjustment accuracy can be secured.

The present invention is not limited to the above embodiments, and the shape and size of each member can be changed as appropriate.

[0047]

[Effect of the device]

 As described above, according to the pickup lens mounting structure of the present invention, the laser light from the pickup lens is emitted by the extremely simple structure in which the center point of the base concave portion is set to the second principal point of the pickup lens. Since the spots do not shift, the spot adjustment can be simplified. This can greatly improve the environment resistance, workability, and productivity. Also, by simplifying the spot adjustment, the inclination of the pickup lens, which cannot be corrected after attachment, can be adjusted with priority, so that the adjustment accuracy can be improved.

[Brief description of drawings]

FIG. 1 is a front view of essential parts showing a state where a pickup lens of an embodiment of a pickup lens mounting structure of the present invention is tilted.

FIG. 2 is a front view of relevant parts showing a state in which tilt adjustment of the pickup lens of the present embodiment is completed.

FIG. 3 is a front view of the present embodiment.

FIG. 4 is a conceptual diagram of a general optical pickup device.

FIG. 5 is a front view of a conventional pickup lens mounting structure.

FIG. 6 is an exploded perspective view of the conventional pickup lens mounting structure shown in FIG.

FIG. 7 is a front view showing an example of an initial state before the pickup lens is attached to the lens holder.

FIG. 8 is a front view showing a state where the spot adjustment of the laser light is performed from FIG. 7.

9 is a front view showing a state where the tilt of the pickup lens is adjusted from FIG.

FIG. 10 is a front view showing a state where the spot adjustment of the laser beam is performed from FIG.

[Explanation of reference numerals] 1 disc 1a recording surface 2 actuator 3 pickup lens 3a lens holder 3b lens fitting hole 4 prism 5 collimator lens 6 beam splitter 7 correction plate 8 concave lens 9 light receiving element 10 diffraction grating 11 light emitting element 12 skew plate 12a sphere Seat 13 Screw 14 Base 14a Recessed portion 15 Spring 16 Screw 17 Support plate 20 Base 20a Recessed portion 23 Support portion 34 Ball seat 30 Pickup lens 30a Lens holder 30b Lens fitting hole H ₁ First principal point H ₂ Second principal point L1 Optical axis L2 optical axis L3 optical axis R, r radius of base recess

[Procedure amendment]

[Submission date] July 8, 1992

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 3

[Correction method] Change

[Correction content]

[Figure 3]

[Procedure Amendment 2]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 5

[Correction method] Change

[Correction content]

[Figure 5]

Claims (1)

[Scope of utility model registration request] 1. An optical pickup device for reading a signal of an optical disc by a laser beam emitted from a light source,
In a pickup lens mounting structure for mounting a pickup lens for irradiating the optical disc with the laser light, a skew plate capable of mounting and adjusting the pickup lens, the skew plate is mounted, and an optical axis which is a central axis of the laser light passes through a center. The base, the R-shaped recess formed in the center of the base with the second principal point of the pickup lens located on the exit side of the laser light from the light source as the center point, and the R-shaped recess so as to contact the recess. A pickup lens mounting structure comprising: a ball seat provided on a skew plate.