JPS63304201A - Lens array and its production - Google Patents

Abstract

PURPOSE:To enable efficient mass production with a simple operation by forming a lens array into the structure in which the lens array juxtaposed with distributed index type lenses are integrated and held in a molding. CONSTITUTION:This lens array has the structure in which the lens array juxtaposed with the columnar distributed index type lenses (lens elements) 1 is integrated and held in the molding 2 molded to a rectangular parallelepiped shape. The shape of the molding 2 is not limited to the shape in this example and any shape which is necessary for directly use as, for example, the lens array, is satisfactory. The optical characteristics of the columnar lens elements 1 are used by selecting the characteristics according to the desired characteristics of the lens array obtd. from the lens arrays made of, for example, inorg. glass and plastics. The always stable mass production of the lens array having the desired quality is thereby enabled with the simple molding operation.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a lens array suitable for use in an image transmission section of a copying machine, facsimile machine, image reading device, etc.

(Prior art) A transparent (light-transmitting) cylindrical body whose refractive index changes continuously in the radial direction from the central axis toward its outer circumferential surface at a rate approximately equal to the square of the distance from the central axis. It functions as a lens, and is called a gradient index lens.

This gradient index lens generally has both end surfaces mirror-polished to parallel planes perpendicular to the central axis, and can be used alone as a microlens for various optical applications, or in large numbers closely arranged and bonded together. It is used as an integrated lens array in image transmission units such as copying machines, and in certain applications, one or both sides of it are used as the spherical surface of some floats.

A lens array having such a structure is disclosed in, for example, Japanese Unexamined Patent Publication No. 56
As disclosed in Japanese Patent No. 47006, a set of spacers is arranged on one substrate having a predetermined planarity,
A large number of cylindrical graded index lenses are arranged in parallel between these spacers to form a lens row, and then another substrate having a predetermined planarity is superimposed on the upper surface of the formed lens row via the spacer. It is manufactured by a method in which a lens array is sandwiched between these two substrates, and in that state, an adhesive is impregnated between each lens, between each lens, a spacer, and the substrate, and then solidified.

[Problems to be solved by the invention]

However, in the method of manufacturing a lens array by forming a lens array on one substrate and sandwiching it between the other substrate as described above, it is difficult to manufacture each member such as the substrate and spacer, and to form the lens array. There are many steps involved, such as bonding and bonding each component, and each step requires skilled or advanced processing techniques and time-consuming processing operations, which limits the ability to reduce manufacturing costs.

For example, processing operations such as polishing and grinding to precisely impart a desired flatness to the substrate that forms the parallel reference plane of the lens element require advanced technology and are time-consuming. In conventional methods, these treatments must be performed for each substrate used.

In addition, skilled techniques are required for alignment when bonding a substrate and a spacer, or when sandwiching a lens array between two substrates, and these alignments must be performed each time each array is manufactured. must be carried out carefully, and it is difficult to stably obtain products of a predetermined quality, and there is a problem that mass production is not possible.

The present invention was made in view of the problems in the manufacturing of conventional lens arrays as described above, and an object of the present invention is to provide a structure that eliminates the use of substrates and spacers, thereby making it possible to overcome the problems in manufacturing conventional lens arrays as described above. It is an object of the present invention to provide a lens array having a structure that solves the problems in the above, has a structure that enables mass production with low production cost, and stable quality, and a method for manufacturing the same.

[Means for solving problems]

The above object can be achieved by the following invention.

That is, the present invention uses a lens array characterized in that a lens array in which a large number of gradient index lenses having a cylindrical shape are arranged in parallel is integrally held in a molded body, and a mold for molding. including its manufacturing method.

In the lens array of the present invention, a mold in which the lens rows are arranged is filled with a material capable of forming a molded object to form a molded object, and the lens rows are integrated and held in the molded object thus obtained. By providing the mold with a structure that corresponds to the desired arrangement precision of lens rows and the shape of the lens array, it is possible to consistently produce a lens array of the desired quality with a simple molding operation using the mold. can be mass-produced.

Therefore, the lens array of the present invention does not require the use of a substrate or spacer as in conventional lens arrays due to its structure. It is no longer necessary to carry out various processes, such as bonding processes with lens arrays, which were obstacles to mass production with low costs and stable quality, and mass production with low costs and stable quality can be achieved.

Hereinafter, an example of a lens array of the present invention and a method for manufacturing the same will be described with reference to the drawings.

FIG. 1 is a side view of an example of the lens array of the present invention.

This lens array has a structure in which a lens array consisting of cylindrical gradient index lenses (hereinafter referred to as lens elements) 1 arranged in parallel is integrated and held in a molded body 2 formed into a rectangular parallelepiped shape. .

Note that the shape of the molded body 2 is not limited to the shape in this example, and may be any shape necessary for direct use as a lens array, for example.

Further, the optical properties of the cylindrical lens element 1 used in the present invention are not particularly limited, and may be selected from those made of inorganic glass or resin depending on the desired properties of the resulting lens array. Just choose and use it. Note that from the viewpoint of handling during the manufacturing process of the lens array, it is convenient to use a lens made of flexible resin.

On the other hand, the molded body 2 can hold the lens array without disturbing its arrangement, and has enough strength to provide the obtained lens array with a predetermined function and maintain its shape. It may be made of any material, but it is desirable that it be easily molded using a mold.

Examples of materials for forming the molded body 2 include commonly known crosslinkable resin compositions such as acrylic resins, epoxy resins, phenol resins, and silicone resins, methyl methacrylate (co)polymers, and the like. Various monomers or mixtures thereof used in the production of known thermoplastic polymers, or polymerizable resin compositions such as slag-like materials in which thermoplastic polymers are dissolved, or in some cases, methyl methacrylate and lauryl methacrylate. Examples include thermoplastic polymer melts having a low softening point, such as copolymers of.

In addition, various additives such as coloring agents such as carbon black and various dyes, and viscosity modifiers may be added to the molded body 2 as desired.

Next, a method for manufacturing a lens array according to the present invention will be explained.

FIG. 2 is a schematic view showing an example of a mold that can be used for manufacturing the lens array of the present invention, in which FIG. 2(A) is a plan view thereof, and FIG. 2(B) is a second A in diagram (A)
2(C) is a sectional view taken along line BB in FIG. 2(A).

The type shown in this example is the parallel guide 5a of the lens element 1.
, 5b, a bottom plate 4, and an upper mold 7, forming a cavity 6 corresponding to the shape of a predetermined molded product.

A pair of paralleling guides 5a and 5b are provided to enable parallelization of the lens elements 1 in a predetermined arrangement state and positional accuracy within the cavity 6, and the interval between these guides is The length is taken to fit the optically effective lens length.

Note that the configuration of the mold used in the present invention is not limited to this example, and can vary depending on the shape of the desired molded product and the lens element 1.
It may be selected appropriately depending on the arrangement. That is, it is also possible to arrange the lens elements 1 in multiple rows, such as two rows.

Further, guides 5a, 5 for paralleling the lens elements 1 provided in the mold
b forms a line on which both ends of the lens element 1 are placed and serves as a parallel reference line, but the number of these guides and their arrangement within the mold will depend on the desired position of the lens element 1 within the mold. As long as a reference line necessary to realize the arrangement can be formed, any form can be taken, such as arranging a large number of guides discontinuously on a predetermined line.

It is also effective to arrange a guide so that the lens element does not float up into the material for forming the molded body.

To manufacture a lens array using this mold, first a predetermined number of L-nons elements 1 are arranged in parallel as shown in FIG. 2 using parallel guides 5a and 5b.

Next, when a predetermined number of lens elements 1 are lined up in the mold, the cavity 6 in the mold is filled with a material capable of forming a molded object as mentioned above, and then molded into a shape according to the mold. A molded article is obtained. In the molded body thus obtained, a lens array is integrally held inside the molded body, as shown by the broken line in FIG.

After the molded body 2 is obtained in this way, the mold 3 is removed. Furthermore, for example, c-c shown in FIG.
The molded body is cut along the b-o line, and the obtained cross section shows that the focusing plane of each end face of the lens element 1 is a parallel plane perpendicular to the axis of each lens element 1, and that a predetermined lens length is obtained. A lens array can be obtained by polishing to obtain a lens array.

In addition, if the shape of the part of the molded body other than the surface to be polished is shaped so that it can be used directly as a lens array,
The product obtained at this stage can be used directly as a lens array.

Further, if necessary, the outer shape of the molded body may be processed.

Furthermore, the molded body is 2
It is also possible to obtain a plurality of lens arrays from one molded body by dividing it into the above parts. In this case, it is necessary to use a lens element 1 that is initially used and has a length that allows for such division.

(Example) Examples of the present invention are shown below.

Example A cylindrical plastic gradient index lens with a diameter of 111 and a length of 25 mm (refractive index distribution constant g = 0.1
Two hundred lenses of 8m "1" were arranged in a line in a mold having the structure shown in FIG. 2 so that two adjacent lenses were in contact with each other.

Next, in the mold, 90 parts by weight of methyl methacrylate monomer,
A liquid composition consisting of 1 part by weight of carbon black, 10 parts by weight of methyl methacrylate polymer, and 1 part by weight of azobisisobutyronitrile was filled, and this was polymerized and solidified in the mold at 70°C.

The obtained molded body is taken out from the mold and is placed into lens element 1.
Cutting and polishing are performed so that the focusing surface of each end face becomes a parallel plane perpendicular to the axis of each lens element 1, and the lens length (20 mm) necessary to form a true 1-magnification image is obtained. A lens array was obtained.

Furthermore, a large number of lens arrays were obtained by reusing the mold and repeating the same operations as above.

Using the lens array obtained in this way, MTF
When evaluated using an evaluation device under the condition of a spatial frequency of 41 p/mm, the performance of the obtained lens array was the same as the performance of the lens element before it was made into an array, and all had good performance without variation. Was. There were also no problems with its shape or strength.

〔Effect of the invention〕

The lens array of the present invention has a structure in which a lens array in which gradient index lenses are arranged in parallel is integrated and held in a molded body, and the molded body can be formed in a mold in which the lens array is arranged in advance. Efficient mass production is possible by a simple operation of filling a material and using the mold to obtain a molded body from the material.

Unlike conventional lens arrays, the lens array of the present invention does not require a substrate or spacer as its constituent elements, and therefore does not require various complicated and time-consuming operations using these. Therefore, according to the present invention, it is possible to mass-produce lens arrays with stable quality at low cost.

[Brief explanation of drawings]

FIG. 1 is a schematic side view of an example of a lens array of the present invention. FIG. 2 is a schematic view showing an example of a mold that can be used for manufacturing the lens array of the present invention, in which FIG. 2(A) is a plan view thereof, and FIG. 2(B) is a second Figure (^)'s^
- A sectional view taken along line A, and FIG. 2(C) is a sectional view taken along line BB in FIG. 2(^). FIG. 3 is a schematic plan view of a molded body obtained from the mold shown in FIG. 2. 1: Gradient index lens (lens element) 2: Molded body 3: Formwork 4: Bottom plate 5a, 5b: Lens parallel guide 6: Cavity

Claims (1)

[Scope of Claims] 1) A lens array characterized in that a lens array in which a large number of gradient index lenses each having a cylindrical shape are arranged in parallel is integrally held in a molded body. 2) The lens array according to claim 1, wherein the molded body is made of resin. 3) A material capable of forming a molded body is filled into a mold in which a lens row in which a large number of gradient index lenses having a cylindrical shape are arranged in parallel is filled, and then a molded body is formed from the material using the mold. A method for manufacturing a lens array, comprising the steps of: forming a molded body, and integrally holding the lens array in the molded body. 4) The material capable of forming the molded body is a resin-forming composition, and after filling the composition into the mold, a resin molded from the composition is formed by the mold to form the molded body. A method for manufacturing a lens array according to claim 3.