JPS6278510A - Optical element holding frame - Google Patents

Abstract

PURPOSE:To reduce a fitting error by providing a receiving seat supporting an optical element to be held so that its optical axis can be roughly aligned with its central axis line and forming an elastic projection suppressing the optical element on the receiving seat in one body. CONSTITUTION:For fixing a collimate lens 6 on a lens holding frame 7, elastic projections 7b-7e are deviated in the direction of an arrow (a) to insert the collimate lens 6 into the lens holding frame 7, and an end surface 6a is engaged with the supporting surface 7f of the lens holding frame 7. After the insertion, the elastic projections 7b-7e are elastically deviated in the direction of an arrow (b), abuts on the other refracting surface 6b of the collimate lens 6, and elastically presses with pressure in the optical axis direction. As a result, the collimate lens 6 is supported by the elastic projections 7b-7e and the receiving seat composed of the supporting surface 7f and an inner periphery surface 7g so that the optical axis and center line of said lens 6 can be aligned, and is fixed on the lens holding frame 7. Thus the fitting error between the collimate lens 6 and the lens holding frame 7 can be minimized.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical element holding frame for fixedly holding various optical elements.

[Conventional technology]

2. Description of the Related Art Optical information recording and reproducing devices that record and reproduce information by projecting a light beam onto an optical recording medium such as an optical disk have been widely put into practical use. In this optical information recording and reproducing device, an optical head is equipped with a light source that emits a light beam, an optical system composed of various optical elements, a photodetector that receives reflected light from a recording medium, etc., and records are recorded from this optical head. Information is recorded or reproduced by projecting a spot-shaped light beam toward the medium.

This optical head projects a light beam emitted from a light source onto a recording medium as a minute spot, and uses various optical systems including an objective lens to guide reflected light or transmitted light from the recording medium to a photodetector. element is installed.

These optical elements must be fixed in the optical path of the optical system by positioning and adjusting in the optical axis direction. Therefore, in conventional optical systems, the optical elements are fixed to a holding frame by adhesive, and this holding frame is attached to the mirror. It is configured to be installed in a cylinder to adjust the position of the optical element in the optical axis direction.

[Problem that the invention seeks to solve]

When an optical element is fixed to an optical element holding frame using an adhesive, there is a drawback that the excess adhesive that protrudes after adhesion must be wiped off, making the work of fixing the optical element cumbersome. Also, it takes a considerable amount of time for the adhesive to harden.
In particular, when an epoxy adhesive having strong adhesive strength is used, it takes a long time to cure the adhesive, which has the disadvantage of being poor in mass production.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to eliminate the above-mentioned drawbacks and to provide an optical element holding frame that can fix an optical element to the holding frame with a simple operation and with high positioning accuracy without using an adhesive. It is.

[Means and effects for solving the problems] The optical element holding frame according to the present invention is composed of an integrally formed plastic body, and supports the optical element to be held so that its optical axis and central axis line substantially coincide with each other. The optical device is characterized in that it has a receiving seat, and an elastic protrusion for restraining the optical element is integrally formed on the receiving seat.

With this configuration, the optical element to be held is elastically pressed in a direction parallel to the optical axis by the integrally molded elastic protrusion, so the optical element can be fixed to the holding frame simply by fitting it into the holding frame. can do.

〔Example〕

FIG. 1 is a diagrammatic sectional view showing the structure of an example of an optical head equipped with an optical element holding frame according to the present invention.

A laser diode 1 constituting a light source is attached to an optical system support body 2 made of a plastic molded body, and a light beam is projected toward a diffraction grating 3. The diffraction grating 3 is attached to the optical system support body 2 via a diffraction grating support frame 4. The light beam transmitted through the diffraction grating 3 is split into three beams,
The beam passes through a beam splitter 5 having a half mirror surface 5a and enters a collimator lens 6. The collimator lens 6 is fixed to a lens holding frame 7 made of a plastic molded body, and after adjusting the position of the holding frame 7 in the optical axis direction, the collimator lens 6 is fitted into the lens barrel 2a of the optical system support body 2. The light beam incident on the collimator lens 6 is focused into a parallel light beam, which is incident on the objective lens 9 which is displaced by the actuator 8 in the optical axis direction and the tracking direction perpendicular thereto, and is irradiated onto the recording medium 10 as a spot. In this example, it is assumed that an information track recorded on the recording medium 10 is to be reproduced. The reflected light beam modulated by this information track is focused by the objective lens 9, passes through the collimator lens 6 again, is reflected by the half mirror surface 5a of the beam splitter 5, passes through the opening 2b provided in the optical system support body, and passes through the concave lens. 11. This concave lens 11 is also fixed to a lens holding frame 12 made of a plastic molded body, and after adjusting the position of this lens holding frame 12 in the optical axis direction, the lens barrel portion 13a of the optical head body 13 is made of a plastic molded body. Fit and install. The light beam transmitted through the concave lens 11 enters a cylindrical lens 14 arranged coaxially with the concave lens 11 . The O-lintrical lens 14 is similarly fixed to a support frame 15 made of a plastic molded body, and this support frame 15 is connected to the lens barrel portion 13a of the optical head main body 13.
Fit and install. The light beam transmitted through the cylindrical lens 14 is incident on a photodiode 16 constituting a light receiving element having a light receiving area divided into six, where it is photoelectrically converted and an information signal and a focusing and tracking error signal are detected.

Figure 2 shows the state in which the collimator lens is fixed to the lens holding frame, Figure 2 A is a front view, □ 2nd
FIG. B is a sectional view taken along the line II in FIG. 2A. In the present invention, the lens holding frame 7 is constructed from an integrally molded plastic body. The holding frame 7 has a cylindrical portion 7a and four elastic protrusions 7b, 7c, 7d, and 7e that protrude in the optical axis direction of the collimator lens 6. Since plastic has strong elasticity when the wall thickness is reduced, the elastic protrusions 7b to 7d are indicated by the arrow a.
Alternatively, it can be elastically deformed in the b direction. One refractive surface 6a of the collimator lens 6 to be held by the lens holding frame 7
The support surface 7f that engages with the curvature of the collimator lens 6 almost matches the curvature of the collimator lens 6, and the inner circumferential surface 7g that engages with the outer circumferential surface centered on the optical axis of the collimator lens 6.
Make it slightly larger than the outer circumferential surface of. To fix the collimator lens 6 to the lens holding frame 7, the four elastic protrusions 7b to 7e are shifted in the direction of arrow a, the collimator lens 6 is inserted into the lens holding frame 7, and the end surface 6a is inserted into the lens holding frame 7. It is engaged with the support surface 7f of the frame 7. Therefore, the collimator lens 6 is positioned and supported with high accuracy by the receiving seat made up of the support surfaces 7f and 7g of the lens holding frame 7. After insertion, the four elastic protrusions 7b to 7e elastically shift in the direction of the arrow mark, come into contact with the other refractive surface 6b of the collimator lens 6, and elastically press it in the optical axis direction. As a result, the collimator lens 6 is supported by the receiving seat consisting of the four elastic protrusions 7b to 7e, the support surface 7f, and the inner circumferential surface 7g, with the optical axis of the collimator lens coinciding with the center line. It is fixed to the lens holding frame 7 by a simple operation without using any agent. especially,
Since a plastic molded body can be molded with high precision, errors in the attachment between the collimator lens 6 and the lens holding frame 7 can be made extremely small.

FIG. 3 shows the configuration of a modified example of the lens holding frame of the present invention, FIG. 3A is a front view, and FIG. 3B is a view of I in FIG. 3A.
It is a sectional view taken along the line F-If. In this example, the lens holding frame 20
2 shows an example in which elastic protrusions 20a extending along the periphery of the collimator lens 6 are integrally formed. Since the elastic protrusions 20a can be elastically deformed in the outer circumferential direction, when the collimator lens 6 is fitted into the lens holding frame 20, the collimator lens 6 is elastically pressed and supported in the optical axis direction by the elastic protrusions 20a. It turns out.

FIG. 4 further shows the configuration of another modified example of the present invention, FIG. 4A is a front view, and FIG. 4B is a view taken along I-I of FIG. 4A.
It is a sectional view taken along line II. In this example, the lens holding frame 30 has four grooves 30a, 30b, 30C, and 3 at equal intervals.
An example is shown in which four elastic protrusions 30e, 30f, 30g, and 30h facing in the optical axis direction of the collimator lens 6 are integrally formed. By forming the grooves 30a to 30e in this way, the elastic protrusion 30e
~30h becomes easier to deform in the outer circumferential direction, so the work of fitting the collimator lens 6 becomes easier.

The present invention is not limited to the embodiments described above, and various modifications are possible. For example, in the above-mentioned embodiment, a lens holding frame for holding a collimator lens was described, but the frame is not limited to a collimator lens, and is a holding frame for holding various optical elements such as a cylindrical lens, a diffraction grating, and a prism. This can also be applied to frames.

〔Effect of the invention〕

As explained above, according to the present invention, the holding frame for holding the optical element is made of a plastic molded body, and the elastic projection protruding in the optical axis direction of the optical element to be held is integrally molded. As a result, the optical element to be held is elastically pressed in a direction parallel to the optical axis by the elastic protrusion, and as a result, the optical element can be fixed to the holding frame simply by fitting it into the holding frame without using adhesive. can.

Furthermore, since the plastic molded body can be molded with high dimensional accuracy, errors in mounting between the optical element and its holding frame can be reduced.

[Brief explanation of drawings]

FIG. 1 is a diagrammatic sectional view showing the configuration of an example of an optical head equipped with an optical element holding frame according to the present invention, and FIGS. 2A and 2B are front views showing the configuration of an example of the optical element holding frame according to the present invention. 3A and 3B are front views and sectional views showing the structure of a modified example of the optical element holding frame according to the present invention, and FIGS. 4 A and B are another modified example of the optical element holding frame according to the present invention. FIG. 2 is a front view and a cross-sectional view showing the configuration of FIG. 1... Laser diode 2... Optical system support body 3
...Diffraction grating 4...Diffraction grating support frame 5.
...Beam splitter 6...Collimator lens 7,
12.15.20.30... Lens holding frame 8... Actuator 9... Objective lens 10... Recording medium 11... Concave lens 13... Optical head body 14... Cylindrical lens 16.・Photodiode

Claims (1)

[Claims] 1. It is composed of an integrally formed plastic body, and has a receiving seat that supports the optical element to be held so that its optical axis and central axis line almost coincide, and an elastic protrusion that restrains the optical element on the receiving seat. An optical element holding frame characterized in that a portion is integrally formed.