JPH0560931A - Graded index plastic rein forming body - Google Patents

Abstract

PURPOSE:To facilitate end surface grinding by consisting of a middle part of a polymer mainly made of alkyl acrylate and by increasing conc. of a fluorocarbon resin in proportion to a distance parting from center in circumferen tial direction to decrease refractive index. CONSTITUTION:The rod 1 of a transparent methacrylate is dipped into the solution 2, in which specific weight ratio of PMMA and poly vinylidene fluoride are dissolved, to deposite the blended product 3 with the ratio in specific thickness on the outer circumference of the PMMA rod. Next, after pulled up and dried, the rod is dipped again into the solution 4 having higher conc. of PVDF than the solution 2 to deposite the blend 5 having lower refractive index than the rod 1. The process is repeated successively. As the result, conc. of fluorocarbon resin increases in proportion to the distance parting from center in circumference direction and distribution of refractive index decreasing in radial direction is attained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gradient index plastic resin molding, and more particularly to a copying machine, a facsimile, and an LE.
The present invention relates to such a resin molded product applied to a reading lens of the same size used for a D printer or the like.

[0002]

2. Description of the Related Art In recent years, in the field of office automation equipment, copying machines, facsimiles, LED printers, etc., are becoming smaller and less costly due to the demands of easy transportation and easy assembly and maintenance due to penetration into the home. There is an increasing demand for an array-type unit-size imaging element that is compatible with the above.

The guiding principle of a conventional gradient index optical fiber is shown in FIG. The gradient index optical fiber has a parabolic refractive index distribution in which the refractive index is largest in the central portion and smaller in the peripheral portion. Since light has a property of bending toward the higher refractive index, an incident light ray in such a fiber travels in a sinusoidal curve having the same period. By utilizing this principle, it is possible to create an erecting equal-magnification image by adjusting the length of a lens in which optical fibers are arrayed and the distance to the object plane.

In the conventional gradient index glass lens, a glass rod containing silicon, lead or the like as a main component is placed with an element (thalium) for increasing the refractive index, and then an element (potassium) for reducing the refractive index is added. Immersion in the melt, and the latter is increased in proportion to the peripheral portion by the ion exchange method. In this way, a glass rod having a parabolic refractive index distribution is formed. After that, this is thinned into a fiber shape to obtain a gradient index optical fiber. Further, a lens array for reading can be obtained by arraying this optical fiber.

[0005]

Since the conventional gradient index fiber array is made of glass, it easily breaks, and when it is formed into an array, it is necessary to polish the end face for use as a lens. There was a limit in reducing the cost. Therefore, an object of the present invention is to provide an optical fiber that uses a plastic material as the gradient index fiber, has good flexibility, and is easy to polish the end face.

[0006]

In order to achieve the above-mentioned object, the present invention comprises a polymer whose main portion is a polyalkyl acrylate as a main component in a circular cross section, and which has an outer circumferential direction. The concentration distribution of the fluororesin increases with the deviation from the center, and the refractive index has a distribution that decreases in the outer peripheral direction, and a gradient index plastic resin molded body, and an image reading formed by arraying this molded body Provide a lens.

[0007]

[Function] When polyvinylidene fluoride (hereinafter referred to as PVDF) and polymethylmethacrylate (hereinafter referred to as PMMA) are uniformly blended, PVD is proportional to the weight fraction as shown in FIG.
The refractive index decreases as F increases. On the other hand, the transmittance of the blended product (thickness: 3 mm) is PVDF as shown in FIG.
It can be seen that up to a blend ratio of about 80% is optically transparent. By utilizing these properties, that is, by forming the plastic rod so that the center portion of the plastic rod has a large weight of PMMA and the PVDF weight fraction increases toward the outer periphery, a gradient index plastic rod can be obtained.

[0008]

EXAMPLE FIG. 3 is an explanatory view of the principle of the method of manufacturing a gradient index plastic rod of the present invention. First, attach the transparent PMMA rod 1 to PMMA and PVDF 1 to n.
Immerse in a solution (eg, dioxane as a solvent) dissolved in a weight ratio of ₁ and deposit the blended product 3 of this ratio on the outer circumference of the PMMA rod to a predetermined thickness. After being dried, it is immersed again in the solution 4 having a higher concentration of PVDF than the solution, and the blend 5 having a lower refractive index than the rod is deposited. A rod having a refractive index distribution can be formed by sequentially repeating such steps and depositing them.

FIG. 4 shows another embodiment of the present invention in which the PMMA rod 11 is dipped in a PMMA mixed solution 12 containing a slight amount of PVDF, and then a solution 13 of PVDF in the same solvent or another solvent is gradually added. Is added to the outer circumference of the rod so as to increase the PVDF concentration so that it has a refractive index distribution. In this method, the poor solvent of PMMA is gradually added to the PMM.
A is initially selectively attached to the rod and the PMMA of the solution
As the concentration of P gradually decreases and goes to the outer circumference, P
There is also a method of increasing the concentration of VDF.

In such a method, for example, a core diameter of 0.5
It is possible to manufacture a plastic rod having a mmφ, a rod diameter of 5 mmφ, a central refractive index of 1.49, and an outer peripheral refractive index of 1.41. Further, in order to manufacture an optical fiber, a cylindrical heater is arranged on the outer circumference of the rod and heating is performed up to around 200 ° C. at which the rod melts. On the other hand, the tip of the rod is spun into an optical fiber by a winding machine to produce a gradient index fiber.

The optical fiber thus produced has a radiation type distribution of, for example, an outer diameter of 1.0φ, a core diameter of 0.1 mmφ, a refractive index of 1.49 at the central portion and 1.41 at the outer periphery. The structure of such an optical fiber can follow a conventional method.
FIG. 5 shows an image reading lens array. A black resin cover (mold) for preventing stray light from the gradient index plastic rod or optical fiber 21 manufactured as described above.
22 to manufacture.

FIG. 6 shows a state in which the lens array of FIG. 5 is applied as an image forming lens of a facsimile. A document 32 is irradiated with light from a light source 31, and reflected light is received by an image reading lens array 33 such as a CCD. An image is formed on the sensor (line sensor) 34 and converted into an electric signal.

[0013]

The gradient index plastic rod of the present invention is thinner than the one made of glass because it has flexibility, the end surface is easily polished, and the difference in refractive index between the core and the clad is large. Therefore, a lens having a refractive index distribution is possible. Further, since it has a lower melting point than glass, it is easy to form a fiber and is difficult to break, so that an array of fibers is easy, and a fiber lens array can be easily provided.

[Brief description of drawings]

FIG. 1 is a relationship diagram of a blending ratio of PMMA and PVDF and a refractive index.

FIG. 2 is a relationship diagram of a blend ratio of PMMA and PVDF and a light transmittance.

FIG. 3 is an explanatory diagram of a method for manufacturing a plastic resin molded body according to an example.

FIG. 4 is an explanatory view of a method for manufacturing a plastic resin molded body of another example.

FIG. 5 is a diagram showing an image reading lens using an arrayed optical fiber.

FIG. 6 is a diagram showing an example in which a lens array is applied to a facsimile.

FIG. 7 is a diagram illustrating the principle of an optical fiber.

[Explanation of symbols]

 1 ... PMMA rod 2, 4 ... PMMA / PVDF mixed solution 3, 5 ... PMMA / PVDF blend layer 11 ... PMMA rod 12 ... PMMA / PVDF mixed solution 13 ... PVDF solution 21 ... Optical fiber 22 ... Resin cover 31 ... Light source 32 ... Document 33 ... Lens array 34 ... Line sensor

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yuji Ojima 1015 Kamiodanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture, Fujitsu Limited (72) Inventor, Eietsu Takahashi 1015, Kamiodanaka, Nakahara-ku, Kawasaki, Kanagawa Prefecture, Fujitsu Limited

Claims (4)

[Claims] 1. A circular cross-section has a central portion composed of a polymer having a polyalkyl acrylate as a main component, and the concentration of the fluororesin increases as it deviates from the center in the outer circumferential direction, and the refractive index increases. Has a distribution that decreases in the outer peripheral direction, a gradient index plastic resin molded product. 2. The molded product according to claim 1, which is an optical fiber. 3. The molded product according to claim 1, wherein the alkyl polyacrylate is polymethyl methacrylate, and the fluororesin is polyvinylidene fluoride. 4. An image reading lens formed by arranging the plastic resin moldings according to claim 1 or 2 in an array.