JP2011216163A - Objective lens - Google Patents

Abstract

PROBLEM TO BE SOLVED: To mount an objective lens to a lens holder of an actuator with high accuracy.SOLUTION: The objective lens 6 comprises a lens section 6A that collects laser light emitted from a laser diode to a signal recording layer formed at an optical disk, a reflection plane 6B which is provided around the lens section 6A and reflects parallel light radiated from an autocollimator device in a direction of the autocollimator device, and a flange 6C provided at an outer periphery of the reflection plane 6B, and prevents the parallel light radiated from the autocollimator device to the flange 6C from being reflected on the autocollimator device.

Description

  The present invention relates to an objective lens used in an optical pickup device that performs reading operation of a signal recorded on an optical disc by laser light.

  2. Description of the Related Art Optical disk apparatuses that can perform signal reproduction operations and signal recording operations by irradiating a signal recording layer of an optical disk with laser light emitted from an optical pickup device have become widespread.

  As an optical disk apparatus, an apparatus using an optical disk called a CD or a DVD is generally widespread. Recently, an optical disk with improved recording density, that is, an apparatus using a Blu-ray standard optical disk has been developed.

  The optical pickup device condenses the laser light emitted from the laser diode onto the signal recording layer provided on the optical disc by the condensing operation of the objective lens, and returns the return light that is a laser reflected from the signal recording layer. It is comprised so that a detector may be irradiated. In other words, a focus error signal and a tracking error signal are generated from a signal obtained in accordance with a change in the light amount or position of a laser beam irradiated to a quadrant sensor or the like incorporated in a photodetector, and these signals are used. Then, by controlling the displacement position of the objective lens, a read operation of a signal recorded on the optical disk is performed.

  The objective lens incorporated in the optical pickup device configured to perform such an operation can perform a displacement operation in a direction perpendicular to the signal surface of the optical disc and a displacement operation in the radial direction of the optical disc. It is fixed to a member called a lens holder supported by a book support wire or the like with an adhesive or the like.

  In the optical pickup device having such a configuration, the objective lens performs the displacement operation for the focus control operation and the tracking control operation by the displacement operation in the direction perpendicular to the signal surface of the optical disk of the lens holder and the displacement operation in the radial direction of the optical disk. Configured to do.

  In order to accurately perform the focus control operation and the tracking control operation described above, it is necessary to assemble the optical pickup device so that the angle of the optical axis of the objective lens with respect to the signal surface of the optical disk is vertical. Such an angle adjustment operation of the objective lens is performed using, for example, an autocollimator device as described in Patent Document 1.

JP 2000-293860 A

The prior art described in Patent Document 1 will be described with reference to FIG. In FIG. 5, reference numeral 1 denotes an autocollimator device, which irradiates parallel light L onto an objective lens incorporated in an optical pickup device 3 placed on a reference table 2 and reflects the laser light reflected from the objective lens. Is configured to receive light. Reference numeral 4 denotes an arithmetic unit that inputs a signal obtained from the autocollimator device 1 and controls the autocollimator device 1, and is configured to adjust the angle of the objective lens from the figure displayed on the display unit 4A. Has been.

  FIG. 6 is a cross-sectional view for explaining the configuration of an objective lens generally used in the past. In the figure, reference numeral 5 denotes a lens holder which is supported by the four support wires so that the displacement operation in the focus direction and the tracking direction can be performed as described above, and the objective lens 6 is bonded as shown in the figure. It is fixed.

  The objective lens 6 is provided around a lens portion 6A for condensing laser light emitted from a laser diode (not shown) on the signal recording layer of the optical disc, and from the autocollimator device 1 A reflection plane portion 6B that reflects the irradiated parallel light L in the direction of the autocollimator apparatus 1 and a flange portion 6C provided on the outer peripheral side of the reflection plane portion 6B.

  The lower surface of the flange portion 6C is in contact with a fixing surface 5A formed on the lens holder 5, and a fixed reference surface that defines a fixing position of the objective lens 6 with respect to the lens holder 5 is formed. The objective lens 6 is adhered and fixed to the lens holder 5. In the optical pickup device incorporating the objective lens 6, the angle of the optical axis of the objective lens 6 is adjusted to be perpendicular to the signal surface of the optical disc. Although the operation | movement to perform is performed using the autocollimator apparatus 1 shown in FIG. 5, description about such adjustment operation is abbreviate | omitted.

  In the objective lens 6 having the configuration shown in FIG. 6, the parallel light L emitted from the autocollimator device 1 is irradiated not only on the reflection flat surface portion 6 </ b> B provided on the objective lens 6 but also on the upper surface portion of the flange portion 6 </ b> C. It will be. As a result, not only the parallel light L reflected from the reflection plane part 6B but also the parallel light L reflected by the upper surface part of the collar part 6C is incident on the autocollimator apparatus 1.

  The autocollimator device 1 outputs a detection signal based on the reflected light of the incident parallel light L to the arithmetic device 4. As a result, the arithmetic device 4 performs arithmetic processing based on the input signal, and displays measurement data based on the arithmetic result on the display unit 4A. Based on the display result, an operation of adjusting the angle of the objective lens 6 incorporated in the optical pickup device 3 is performed.

  When such an angle adjustment operation of the objective lens 6 is performed, the display unit 4A of the arithmetic device 4 includes not only the parallel light L reflected from the reflection plane unit 6B provided on the objective lens 6 but also the collar unit 6C. Since the measurement data based on the parallel light L reflected from the upper surface of the display is displayed, the point image displayed on the display unit 4A becomes unclear and an accurate angle adjustment operation cannot be performed. There is a problem.

  The present invention is intended to provide an objective lens that can solve such a problem.

  The present invention provides a lens unit for condensing laser light emitted from a laser diode onto a signal recording layer provided on an optical disc, and parallel light emitted from an autocollimator device provided around the lens unit. In an objective lens in which a reflection plane part that reflects in the direction of the autocollimator apparatus and a collar part is formed on the outer periphery of the reflection plane part, the autocollimator apparatus applies parallel light from the autocollimator apparatus that irradiates the collar part. It is characterized by not reflecting the light.

Further, the present invention is characterized in that the parallel light applied to the collar is irregularly reflected by subjecting the surface of the collar formed on the objective lens to a texture.

  The present invention is characterized in that by forming an inclined surface on the collar part formed on the objective lens, parallel light irradiated on the collar part is reflected in a different direction from the autocollimator device. Is.

  Further, the present invention is characterized in that the inclination direction of the inclined surface is set so that the reflection direction of the parallel light reflected from the inclined surface formed on the flange portion of the objective lens is the outer peripheral direction of the lens. is there.

  The objective lens of the present invention is configured so that the parallel light reflected from the collar portion provided on the outer peripheral portion of the reflection plane portion used when adjusting the angle of the objective lens is not incident on the autocollimator device. The point image displayed on the display unit provided to display data based on the measurement signal obtained from the autocollimator device becomes clear. Therefore, according to the objective lens of the present invention, the adjustment operation by the autocollimator device that adjusts the optical axis of the objective lens to be perpendicular to the signal surface of the optical disc can be performed accurately.

It is sectional drawing for demonstrating the structure of the objective lens which concerns on this invention. It is a top view of the objective lens which concerns on this invention. It is sectional drawing for demonstrating the structure of the objective lens which concerns on this invention. It is a top view of the objective lens which concerns on this invention. It is the schematic for demonstrating the adjustment operation | movement by an autocollimator apparatus. It is sectional drawing for demonstrating the structure of the conventional objective lens.

  The present invention relates to an objective lens capable of accurately adjusting the angle of an objective lens that focuses laser light emitted from a laser diode onto a signal recording layer of an optical disc.

  FIG. 1 is a cross-sectional view for explaining the configuration of an objective lens incorporated in the optical pickup device of the present invention. The same reference numerals are given to the same components as those in the conventional example shown in FIG. The objective lens 6 of the present invention is characterized in that the upper surface 6D of the flange portion 6C provided on the outer peripheral portion of the reflective flat surface portion 6B is subjected to a texture process.

  FIG. 2 is a plan view of the objective lens 6 in which the upper surface 6D of the flange portion 6C is subjected to a texture process, and the reflection planar portion 6B and the flange portion 6C in which the upper surface 6D is textured are formed in an annular shape. With the objective lens 6 having such a configuration, even if the parallel light L emitted from the autocollimator device 1 is applied to the upper surface 6D of the reflection plane portion 6B and the collar portion 6C, the parallel light is irradiated to the upper surface 6D of the collar portion 6C. Since the light L is irregularly reflected by the textured upper surface 6D, the parallel light L irradiated on the upper surface 6D of the collar 6C is not incident on the autocollimator device 1.

  Therefore, since only the parallel light reflected from the reflection flat surface portion 6B formed on the objective lens 6 is incident on the autocollimator device 1, the point image displayed on the display portion 4A is clearly displayed. I can do it. Therefore, according to the objective lens 6 of the present invention, the optical axis angle of the objective lens 6 can be adjusted accurately.

In addition, since the objective lens 6 of the present invention is formed with the collar portion 6C in which the reflection flat surface portion 6B and the upper surface 6D are subjected to the textured process, the optical axis of the autocollimator device 1 is no matter where the objective lens 6 is rotated. Angle adjustment can be performed accurately without any problem.

  A second embodiment will be described with reference to FIGS. 3 and 4. The same components as those in the first embodiment shown in FIG. The objective lens 6 of Example 2 is characterized in that an inclined surface 6E is formed on the upper surface of a flange portion 6C provided on the outer peripheral portion of the reflective flat surface portion 6B.

  FIG. 2 is a plan view of the objective lens 6 in which the inclined surface 6E is formed on the upper surface of the flange portion 6C. The flange portion 6C on which the reflection plane portion 6B and the inclined surface 6E are formed is formed in an annular shape. With the objective lens 6 having such a configuration, even if the parallel light L emitted from the autocollimator device 1 is applied to the inclined plane 6E of the reflection plane portion 6B and the flange portion 6C, it is irradiated to the inclined surface 6E of the flange portion 6C. Since the parallel light L reflected from the inclined surface 6E is reflected to the outside of the objective lens 6 as shown in the figure, the parallel light L applied to the inclined surface 6E of the flange 6C is incident on the autocollimator device 1. There is nothing.

  Therefore, since only the parallel light reflected from the reflection flat surface portion 6B formed on the objective lens 6 is incident on the autocollimator device 1, the point image displayed on the display portion 4A is clearly displayed. I can do it. Therefore, according to the objective lens 6 of the present invention, the optical axis angle of the objective lens 6 can be adjusted accurately.

  In addition, since the objective lens 6 of the present invention is formed with the collar portion 6C in which the reflection plane portion 6B and the inclined surface 6E are formed in an annular shape, the light emitted from the autocollimator device 1 can be used wherever the rotational position of the objective lens 6 is. The shaft angle can be adjusted accurately without any problem.

  Furthermore, the inclined surface 6E formed on the flange portion 6C of the objective lens 6 of the present invention is configured such that the reflection direction of the parallel light L reflected by the inclined surface 6E is the outer peripheral direction of the objective lens 6. Therefore, the reflected parallel lights L do not interfere with each other, and the parallel light L used for the measurement operation by the autocollimator device 1, that is, the parallel light L reflected from the reflection plane portion 6B is accurately measured. I can do it.

  In the embodiment of the present invention, the texture processing applied to the upper surface 6D of the collar portion 6C can be variously performed such as satin, wood grain, and texture.

5 Lens holder 6 Objective lens 6A Lens part 6B Reflective plane part 6C Gutter part 6D Upper surface 6E Inclined surface L Parallel light

Claims (4)

A lens unit for condensing laser light emitted from a laser diode onto a signal recording layer provided on an optical disk, and parallel light emitted from an autocollimator device provided around the lens unit. An objective lens having a reflection plane portion that reflects in the direction and a flange portion formed on the outer periphery of the reflection plane portion, and does not reflect parallel light from the autocollimator device irradiated on the flange portion to the autocollimator device An objective lens that is characterized by the above. 2. The objective lens according to claim 1, wherein the parallel light applied to the collar is irregularly reflected by applying a texture to the surface of the collar. 2. The objective lens according to claim 1, wherein the inclined surface is formed on the collar portion so that parallel light irradiated on the collar portion is reflected in a direction different from that of the autocollimator device. 4. The objective lens according to claim 3, wherein the inclination direction of the inclined surface is set so that the reflection direction of the parallel light reflected from the inclined surface is the outer peripheral direction of the lens.

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