JPH06317716A - Sheet-shaped plastic optical fiber - Google Patents

Abstract

PURPOSE:To drastically increase the quantity of light transmitted per unit area, to form a homogeneous and distinct image and to facilitate secondary working by hot-pressing plural optical fibers attached firmly to one another in to form the sheet-shaped plastic optical fiber. CONSTITUTION:The desired number of plastic optical fibers 1 firmly attached to one another in parallel are placed in a mold and hot-pressed at a temp. below the m.p. of the core of the fiber 1 and above the glass transition temp. to produce a sheet-shaped plastic optical fiber F0. The pressure to be applied is appropriately selected so that the core of the optical fiber 1 is not deformed. The core is deformed and the optical characteristic is deteriorated when the fibers are hot-pressed to a completely square section, and hence the thickness of the sheet is controlled to slightly larger than 0.785R (where R is the diameter of the fiber 1). Consequently, the quantity of light transmitted per unit area of the sensor, light guide, etc., is drastically increased, the contact part between the fibers is made linear, and the distinctness of an image is enhanced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet-shaped plastic optical fiber useful as a component of various line-type sensors, line-type light guides and line-type image sensors, liquid crystal display devices and the like.

[0002]

2. Description of the Related Art Plastic optical fibers are flexible and have a large diameter and high NA characteristics, and are therefore widely used as various sensors and light guides in various fields including the field of optical communication. Since a commonly used optical fiber is a cylindrical molded body having a cross-sectional diameter of about 0.1 to 3.0 mm, a plurality of optical fibers (1) can be directly or adhesively bonded (for example, as shown in FIG. 11). In many cases, they are used by tightly bundling or arranging them by interposing 7) or by bundling a large number of optical fibers in a cylindrical or prismatic shape.

However, in such a usage mode, the amount of transmitted light per unit area of a sensor, a light guide or the like is increased due to the presence of a relatively large gap between the fibers or an adhesive filling the gap. There is room for improvement in terms of detection sensitivity and uniform and clear image formation.
Further, it is not easy to carry out secondary processing by bundling or arranging a large number of cylindrical optical fibers regularly and closely.

[0004]

SUMMARY OF THE INVENTION The present invention solves the above problems, and when incorporated into a sensor, a light guide, a liquid crystal device or the like, the amount of transmitted light per unit area thereof is significantly increased to form an image. The purpose of the invention is to provide a plastic optical fiber which is uniform and clear and which can be easily subjected to secondary processing.

[0005]

That is, the present invention relates to a sheet-shaped plastic optical fiber formed by thermocompression bonding a plurality of plastic optical fibers in a close parallel state.

The present invention will be described below with reference to the accompanying drawings. FIG. 1 is a schematic perspective view showing an embodiment of the sheet-shaped plastic optical fiber (F ₀ ) according to the present invention.
FIG. 2 is an enlarged perspective view showing a part of FIG. 1. As is clear by comparing these figures with FIG. 11 showing a schematic cross section of the conventional plastic optical fiber array, in the case of the sheet-shaped plastic optical fiber (F ₀ ) according to the present invention,
Since the respective fibers are thermocompression-bonded to each other within the limit that the core portion is not deformed, the gap between the fibers is extremely small as shown in FIG. Therefore, the amount of transmitted light per unit area of a sensor or light guide in which such a sheet-shaped plastic optical fiber is embedded is
This is significantly larger than the case of a sensor or the like incorporating a conventional plastic optical fiber array. Furthermore, the sharpness of the image is increased because the contact portions between the fibers are in linear contact.

The sheet-shaped plastic optical fiber (F ₀ ) according to the present invention is not limited to a single-layered one as shown in FIG. 1, but if desired, the plastic optical fibers are thermocompression-bonded in a multi-layered structure of two or more layers. The present invention also includes ones having a structure of two or more layers obtained by adhering a single-layered product and a single-layered product with an adhesive.

As the plastic optical fiber (1) which is a constituent member of the sheet-shaped plastic optical fiber (F ₀ ) according to the present invention, all known in the art can be used. A commonly used fiber is a plastic optical fiber consisting of a single core made of an acrylic polymer and a clad made of a fluoropolymer, but has a structure in which many cores having a diameter of about 15 μ are embedded in a clad resin such as a fluoropolymer. You may use a plastic image fiber. The outer wall of the fiber is made of metal (for example, A
l, Cu, Cr, Ni, Cr alloy, Ni alloy, etc.) or colored organic paint (eg acrylic paint,
It is also possible to use an optical fiber having an increased effect of blocking light transmitted through the fiber by coating with a coating film of urethane-based paint, UV paint, etc.). The thickness of the coating layer is usually 0.1-10 μm. Since the sheet-shaped plastic image fiber has a large number of pixels,
A particularly bright image is obtained, and, for example, the reading accuracy is significantly improved. In this case, when a light-shielding pigment, dye, or the like, which is appropriately selected according to the wavelength of transmitted light, is appropriately mixed in the clad portion, for example, when used as an input device of a sensor or a scanner, the resolution of image information is dramatically increased. improves. The outer diameters of commonly used plastic optical fibers are 0.125 mm, 0.250 mm, 0.500 m.
Examples include m, 0.750 mm, 1.000 mm, 2.000 mm, and 3.000 mm, but are not limited to these.

A preferred method for producing the sheet-shaped plastic optical fiber (F ₀ ) according to the present invention will be described with reference to FIG. Sheet-shaped plastic optical fiber according to the present invention
(F ₀ ) is the desired number of plastic optical fibers (1)
After closely and parallelly loaded into a mold composed of an upper mold (2), a middle mold (3) and a lower mold (4), the fibers were heated under a heating condition of a glass transition temperature or higher which does not exceed the melting point of the core material of the fiber. Manufactured by thermocompression bonding a loaded plastic optical fiber. Commonly used temperature is 110-120
℃. The applied pressure may be appropriately selected within the limit that the core portion of the optical fiber is not deformed, and is not particularly limited, but the pressure usually used is 5 to 30 kg / cm ² .

When the cross-sectional shape of each fiber constituting the sheet-shaped plastic optical fiber manufactured by the method of the present invention is a perfect quadrangle, the thickness of the sheet is 0.785R, where R is the diameter of the raw material fiber. .
However, when thermocompression bonding is performed using a plastic optical fiber that is currently commercially available and is commonly used so that the cross section becomes a perfect square, the core part is deformed and its optical characteristics are impaired. In order to prevent this, the clearance of the mold is adjusted so that the thickness of the sheet is slightly larger than 0.785R. When the raw optical fiber is a plastic image fiber, a large number of cores are densely packed. Therefore, in order to suppress the deformation of the core existing in the peripheral portion of the fiber as much as possible, the thickness of the sheet is set to that of an ordinary plastic optical fiber. It is preferably about 10% larger than the case.
For such a purpose, it is preferable to set the mold temperature for thermocompression bonding of the plastic image fiber to be about 3 to 7 ° C. lower than that for a normal optical fiber.

The multilayer sheet-shaped plastic optical fiber is manufactured by stacking and loading a desired number of plastic optical fibers (1) in a mold shown in FIG. . Further, it is also included in the present invention that the thermocompression bonding process is performed in a continuous process by continuously inserting the plastic optical fiber from one end of the mold, thermocompression bonding in the mold, and taking out from the other end while cooling. It

The sheet-shaped plastic optical fiber according to the present invention is particularly useful as a constituent member of various line type sensors, line type light guides, liquid crystal display devices and the like. For example, as shown in FIG.
(5) For example, a sheet-shaped plastic optical fiber (F ₀ ) according to the present invention, in particular, one manufactured from a plastic image fiber is embedded in a frame made of glass, plastic or metal, and the end portion of the optical fiber array is embedded. An optical device obtained by polishing a surface has a large amount of transmitted light and forms a uniform and clear character or image in every corner. Therefore, an input / output device for information or image processing, for example, LE
It is suitable as a light irradiation device for a D printer and an input device for a contact type image sensor or an image scanner, and their applications will be described in more detail.

A light emitting device for an LED printer generally has a form as shown in FIG. 4, but when an LED head (fiber array embedded in a frame) is provided so as to contact the inner surface of the photosensitive drum. In Figure 5
It is preferable that the lens has a convex lens shape as shown in FIG.

In the case of the contact type image sensor, since the optical fiber part of the reading head and the semiconductor sensor are laminated, there is a problem that the light for illuminating the original cannot be sufficiently taken into the optical fiber part. Affect the. Such a problem is, as shown in FIG. 6, that the sheet-like plastic optical fiber (F ₀ ) according to the present invention, in particular, the sheet-like array made of plastic image fiber is framed in close contact with the transparent body (6).
(5) It is solved by using an optical head embedded in the inside. That is, after sufficient illumination light passing through the transparent body (6) enters the fiber array, the light is reflected by the document surface and the image is transmitted to the sensor. The material of the transparent body (6) may be transparent glass, plastic or the like, but a transparent acrylic resin or polycarbonate resin molded body is preferable from the viewpoint of productivity and cost. Also the frame
(5) may be made transparent by being integrated with the transparent body (6), but from the viewpoints of bonding with the sensor part, blocking of unnecessary light, etc., a light-shielding frame, especially colored black Preferred are plastic frames.

Image scanners, especially hand scanners, are required to be small, thin and lightweight, but the sheet-like plastic optical fiber (F ₀ ) according to the present invention is in close contact with the transparent body (6) and the frame (5). An optical head embedded inside, for example, a compact and thin optical head as shown in FIG. 7 satisfies such a requirement. In this case, when the frame (5) is a transparent frame, the transparent body (6)
Is unnecessary. From the viewpoint of operability of the hand scanner and reading accuracy during movement, as shown in FIG.
It is preferable that the sheet-like plastic optical fibers (F ₀ ) are embedded in parallel in the frame (5) with the transparent body (6) interposed. It should be noted that the pen-type hand scanner having a configuration as shown in FIG. 9 can have a longer length than a long diameter,
It is suitable because it is easy to hold.

Operation of the optical head by subjecting the end face of the optical head having the configuration as shown in FIGS. 4 to 9 to polishing or cutting along an arbitrary flat surface or curved surface. It is possible to improve the performance, the performance of capturing image information on the document surface, and the like. Further, in the contact type image sensor or image scanner, since the number of contact between the end surface of the fiber array and the read document is very large, the end surface is worn and the image reading accuracy is deteriorated. However, such a problem can be solved by forming a transparent cured coating layer on the end face. Examples of the transparent cured coating layer include UV curable coating agents such as acrylic UV hard coat paints and urethane UV hard coat paints.

The method for embedding the sheet-shaped plastic optical fiber (F ₀ ) in the frame (5) according to the present invention is not particularly limited and may be appropriately selected. For example, it is convenient to embed the precisely cut fiber array in the frame with an adhesive after polishing one or both end faces, if desired. In the case of the embodiment shown in FIGS. 6 to 9, the fiber array and the transparent body may be adhesively embedded in a close contact state. When the material of the frame is plastic, the fiber array may be integrated with the frame by placing the fiber array in a mold having a desired shape and then casting a resin for the frame into the mold. . In the case where transparent bodies are arranged in parallel, a mold for securing a space for burying a fiber array and a transparent body are arranged in close contact with each other in a mold of a desired shape, and then the molds other than the mold are The transparent body and the frame may be integrated by casting a resin for the frame in the mold, and then the fiber array may be adhesively embedded in the space adjacent to the transparent body, or the transparent body may be embedded in the mold. The transparent body and the fiber array may be integrated with the frame by arranging the fiber array in a close state and then casting a resin for the frame into the mold.

An optical fiber obtained by polishing or cutting the side surface of the sheet-like plastic optical fiber shown in FIG. 1 along its diagonal line or arbitrary straight line or curved line.
(See FIG. 10) shows a uniform light distribution as a planar light emitter, and is therefore suitable as a device for liquid crystal backlight illumination and the like. For such applications, the multilayer sheet plastic optical fiber is more effective than the single layer sheet plastic optical fiber.

In addition, the sheet-shaped plastic optical fiber according to the present invention is used as an illuminating light guide for displaying the position of an automobile shift lever, a light-receiving device for transmitting light transmission or blocking to a light-receiving element of a line type sensor as information, and a FAX.
It can be effectively used as a reading device for reading, a reading device for copying, a reading device for barcode scanner, a reading device for electronic blackboard, and a line type light guide for optical decoration.

[0020]

EXAMPLES The present invention will be described below with reference to examples. Example 1 Plastic optical fiber "Luminus DB-2000" manufactured by Asahi Kasei Corporation (outer diameter 2.00 mm, length 60 mm) 1
Fifteen pieces were loaded in a mold heated to 70 ° C. in a close parallel state as shown in FIG. The temperature inside the mold was raised to 120 ° C. in 15 minutes under no-pressure condition, and then the temperature inside the mold was adjusted to 1 ° C. under the condition that a pressure of 30 kg / cm ² was applied to the optical fiber arrays arranged in close parallel.
After holding at 20 ° C. for 5 minutes, the pressure was released to 70 ° C. in 20 minutes, the pressure was released, and the pressure-bonded sheet-shaped plastic optical fiber was taken out from the mold. The size of the obtained sheet-shaped plastic optical fiber is 228 in width.
mm, length 60 mm, and thickness 1.6 mm.

Example 2 "Plastic image fiber" manufactured by Asahi Kasei Corporation (outer diameter: 2.00 mm, length: 60 mm, number of pixels: about 3)
115 pieces of 500) were loaded in a mold heated to 70 ° C. in a close parallel state as shown in FIG. The temperature inside the mold is raised to 113 ° C. in 20 minutes under no pressure condition, and then the temperature is increased to 30 ° C. in a closely aligned optical fiber array.
Under the condition that the pressure of kg / cm ² is applied, the temperature inside the mold is maintained at 113 ° C for 10 minutes, and then the temperature is maintained at 7 ° C for 20 minutes.
The pressure was released while the temperature was lowered to 0 ° C., and the crimped sheet-shaped plastic image fiber was taken out from the mold. The dimensions of the obtained sheet-shaped plastic optical fiber were 228 mm in width, 60 mm in length, and 1.75 mm in thickness.

[0022]

Since the sheet-shaped plastic optical fiber according to the present invention has substantially no gaps between constituent fibers, the amount of transmitted light per unit area of a sensor, a light guide or the like incorporating the same is significantly larger than that of a conventional product. Higher image formation makes the image formation uniform and clear, and secondary processing becomes extremely easy.

[Brief description of drawings]

FIG. 1 is a schematic perspective view showing an embodiment of a sheet-shaped plastic optical fiber according to the present invention.

FIG. 2 is an enlarged perspective view showing a part of FIG.

FIG. 3 is a schematic cross-sectional view showing a state in which plastic optical fibers are closely packed in a mold.

FIG. 4 is a schematic perspective view of an optical device in which a sheet-shaped plastic optical fiber according to the present invention is embedded in a frame.

FIG. 5 is a schematic perspective view showing one embodiment of a light irradiation device for an LED printer.

FIG. 6 is a schematic perspective view showing one embodiment of an input device for a contact image sensor.

FIG. 7 is a schematic perspective view showing one embodiment of a contact type hand scanner.

FIG. 8 is a schematic perspective view showing another aspect of the contact type hand scanner.

FIG. 9 is a schematic perspective view showing still another aspect of the contact type hand scanner.

FIG. 10 is a schematic perspective view of a liquid crystal backlight illuminating device obtained by polishing or cutting a side surface of the sheet-shaped plastic optical fiber shown in FIG. 1 along a diagonal line thereof.

FIG. 11 is a schematic cross-sectional view of a conventional plastic optical fiber array connected by an adhesive.

[Explanation of symbols]

1 plastic optical fiber 2 upper mold 3 medium size 4 lower mold 5 frame 6 transparent body 7 adhesive F ₀ sheet plastic optical fiber

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display location G02B 6/06 Z

Claims (10)

[Claims] 1. A sheet-shaped plastic optical fiber formed by thermocompression bonding a plurality of plastic optical fibers in a closely parallel state. 2. The sheet-shaped plastic optical fiber according to claim 1, wherein the plastic optical fiber is a plastic optical fiber whose outer peripheral wall is coated with a metal coating or an organic coating. 3. The sheet-shaped plastic optical fiber according to claim 1, wherein the plastic optical fiber is a plastic image fiber. 4. The sheet-shaped plastic optical fiber according to claim 3, wherein the clad is a light-shielding clad. 5. A plurality of plastic optical fibers are loaded in a mold in a closely parallel state, and the loaded plastic optical fibers are thermocompression-bonded under a heating condition of a glass transition temperature or higher which does not exceed the melting point of the core material of the fibers. The method for producing a sheet-shaped plastic optical fiber according to any one of claims 1 to 4, characterized in that: 6. The method according to claim 5, wherein the thermocompression bonding is performed under a pressure of 5 to 30 kg / cm ² . 7. A light irradiation device for an LED printer, comprising the sheet-shaped plastic optical fiber according to claim 1 embedded in a frame. 8. An input device for a contact type image sensor or an image scanner, comprising the sheet-shaped plastic optical fiber according to claim 1 buried in a frame. 9. An input device for a contact type image sensor or an image scanner, which comprises the sheet-shaped plastic optical fiber according to any one of claims 1 to 4 and a transparent body embedded in a frame in a close contact state. 10. A device for illuminating a liquid crystal backlight, which comprises polishing or cutting a side surface of the sheet-shaped plastic optical fiber according to any one of claims 1 to 4 along a diagonal line or an arbitrary straight line or curve.