JPH0718962B2 - Light guide and manufacturing method thereof - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a light guide used for light beam propagation and image transmission by an optical fiber bundle, and a manufacturing method thereof. More specifically, the present invention relates to a light guide capable of condensing, diffusing, enlarging and reducing an image by changing the area of the incident end face and the emitting end face, and an improvement of a manufacturing method thereof.

[Prior art]

Optical fiber bundles are diversified into image guides (fiberscopes) and light guides (illuminators for copiers, decorative displays, small bending flashlights) because the direction of light flux propagation is easy to change.

Conventionally, for condensing, diffusing, or enlarging or reducing the image,
A light guide in which optical fibers 1 having different thicknesses are bundled as shown in FIG. 1 and a light guide in which the cross section area is changed by changing the cutting angle of the optical fiber bundle as shown in FIG.
Further, the light guide for image transmission is formed by connecting the end faces in an array to the light diffusion plate 2 as shown in FIG.

However, conventional light guides have the disadvantages of cutting the optical fiber bundle to a specific length and then bundling it, which often involves waste of optical fibers and requires special optical fibers that are not easy to manufacture. Was there.

[Object of the Invention]

An object of the present invention is to provide an inexpensive and high-quality light guide by a manufacturing method that is highly producible in mass production and has little waste of optical fibers.

[Summary of Invention]

The light guide of the present invention has a circular or elliptical shape, an optical fiber wound around a bobbin having a cross section of a substantially circular shape (oval, a rectangle with sharp edges dropped), and after fixing the optical fiber, the incident surface covers all the optical fibers, It is obtained by cutting the emitting surface. Since the optical fiber is wound in a straight line on the bobbin and then is simply cut, a light guide with low cost and good throughput can be obtained.

〔Example〕

Example 1. FIG. 4 is a sketch of a case where a plastic fiber is wound on a bobbin having a circular cross section to obtain the maximum light diffusion rate. The plastic fiber 3 is a commercially available total reflection type fiber having a PMMA resin core, and is wound around the bobbin 4 in an aligned manner. Incidentally, reference numeral 10 in the drawing denotes a rotary shaft when the plastic fiber 3 is wound around the bobbin 4 in an aligned manner. The aligned and wound plastic fibers 3 are orthogonal to the rotation axis 10 and are formed in a first cross section 11 formed in the first circumference of the winding start, and from the outer circumference of this first cross section to the end of the winding. A second cross section 12 formed up to the circumference. The radius 5 of the bobbin is determined with respect to the fiber diameter so that the light transmittance does not decrease. The bonding between the fibers was performed by applying a two-component curing type epoxy adhesive while aligning and winding it. After fixing, it is taken out from the bobbin and cut by an ultrasonic cutter as shown by the solid line in FIG. That is, the surface that intersects the circumference 13 that surrounds the first cross section 11 and the circumference 14 that surrounds the second cross section 12 is the cross section 15, and the surface that is in contact with the circumference 13 and that intersects the circumference 14 is the cross section.
There are 16. After cutting, the incident light end face 6 is mirror-polished, and the outgoing light end face 7 is roughened so as to scatter light. In the cutting method of FIG. 5, two light guides of 3,8 having different shapes are simultaneously obtained as shown in FIG. Also, as shown in FIGS. 4 and 5, there is no waste of fiber.

The cutting method is not limited to the case shown in FIG. As shown in FIG. 6, the maximum light collection and diffusion rate can be obtained by cutting the cross section passing through the center of the circle and the cross section in contact with the inner circle.
Further, in the case of the light guide shown in FIG. 4, the expansion and contraction of only one side is required. By combining two light guides as shown in FIG. 7, the surface can be enlarged or reduced. This is because image enlargement / reduction, light beam condensing, and light scattering can be performed on the surface.
It is the best lighting method.

Example 2. FIG. 8 shows a cross-sectional view when the manufacturing bobbin has an elliptical shape. The fibers used are the plastic fibers of PMMA resin as in Example 1. As can be understood from FIG. 8, the advantage of adopting the elliptical cross-section bobbin is that it is non-linear, but the enlargement / reduction ratio can be made larger than that of a circle.

Example 3 FIG. 9 is a sectional view showing a case where the manufacturing bobbin has a square shape with sharp edges dropped. If the cutting is performed as shown by the solid line, it is possible to bundle the linear fibers and obtain a light guide similar to that obtained by cutting.

Example 4. FIG. 10 shows a case where the incident end face and the outgoing end face are not parallel to the rotation axis of the bobbin. Although one side is parallel in FIG. 10, both sides can be deviated from parallel. in this case,
Although image transmission is non-linear, image processing that makes use of this effect is possible. Of course, it is effective as a simple light flux transmitting means.

Embodiment 5 FIG. 11 shows a case where the parallel cross-sectional shape including the rotating shaft (one-dot chain line) of the winding bobbin is not rectangular. After winding, the bobbin is divided by the broken line in FIG. 11, and the fiber bundle is taken out. The exit end face and the incident end face are cut in Example 1
It is carried out according to 4.

Although the present invention has been described in detail with reference to the examples, the types of optical fibers, the cutting method, the bonding method, and the like can be applied to the present invention as long as they are the methods used for ordinary fibers.

〔The invention's effect〕

INDUSTRIAL APPLICABILITY The light guide and the manufacturing method thereof according to the present invention enable low-cost and simple manufacturing, enlargement and reduction of various images, and nonlinear image conversion, and display image transmission means and lighting means of various display devices. Is especially effective as

[Brief description of drawings]

FIG. 1 shows a conventional light guide in which the fiber diameter is changed. FIG. 2 shows a conventional light guide with a different cutting angle. FIG. 3 shows a conventional image guide using a light diffusion plate. 4 (a) and 4 (b) are sketches of the light guide according to the present invention. FIG. 5 shows a cutting position in the case of a circular cross section. FIG. 6 shows another cutting position in the case of a circular cross section. FIG. 7 is an image guide in which two light guides are combined. FIG. 8 shows a cutting example in the case of an elliptical cross section. FIG. 9 shows a cutting example in the case of a rectangular cross section. FIG. 10 shows a cutting example that is not parallel to the rotation axis. FIG. 11 is a sectional view of the bobbin. 1 ... Plastic fiber (optical fiber) 3 ... Light guide 4 ... Bobbin 6 ... Incident light end face 7 ... Emitting light end face 8 ... Light guide 10 ... Rotation axis 11 ... First cross section 12 ... Second cross section 13 ... First Circumference surrounding cross section 14 ... Circumference surrounding second cross section

Claims (4)

[Claims] 1. A light guide for bundling a large number of optical fibers and propagating a light beam, wherein the optical fibers are provided in a first cross section orthogonal to a rotation axis at the time of bundling and a second cross section larger than the first cross section. It is aligned and wound, and the incident end face or the output end face intersects with a circumference surrounding the first cross section and a circumference surrounding the second cross section, or
A light guide, wherein the light guide is in contact with a circumference surrounding the first cross section. 2. A method of manufacturing a light guide in which a large number of optical fibers are bound and a light beam is propagated, wherein the optical fibers are provided on a bobbin having a first cross section corresponding to a winding start of the optical fibers. An optical fiber bundle is formed by aligning and winding up to a circumference surrounding a second cross section larger than the cross section, and the optical fiber bundle intersects the circumference surrounding the first cross section and the circumference surrounding the second cross section, or A method for manufacturing a light guide, characterized in that the light guide is cut so as to be in contact with a circumference surrounding the first cross section to form an incident end face or an emitting end face. 3. The method for manufacturing a light guide according to claim 2, wherein the first cross section orthogonal to the rotation axis of the bobbin for manufacturing the light guide is a circle. 4. The method for manufacturing a light guide according to claim 2, wherein the first cross section orthogonal to the rotation axis of the bobbin for manufacturing the light guide is a substantially circular shape.