JPH03214101A - Closed packed lens array - Google Patents

Abstract

PURPOSE:To obtain nearly 100% condensing efficiency by arranging and forming many recesses, the bottom wall of each of which has a curved shape, in a close-packed state in which the recesses are in contact with each other with the ridge lines of the flatly viewed polygonal shape as boundaries on at least one surface side of a flat plate transparent substrate. CONSTITUTION:The many recesses 12, the bottom wall surface 12A of each of which has the curved surface, are formed on one surface side of the flat plate substrate 11 consisting of a transparent material. The transparent material 14, such as resin or glass, having the refractive index larger than the refractive index of the substrate 11 is packed into the respective recesses 12 to form the respective lens parts 10A of the lens array. The entire part of the surface is thereafter finished to a flat surface, by which the lens array 10 is obtd. The respective lenses 10A constituting the lens, therefore, line up closely in the repetitive patterns of the polygonal shapes and the non-lens parts in the conventional products are eliminated. The incident light to the glass substrate is condensed by any lens regardless of the incident positions thereof and the light spot array is obtd. with the nearly 100% condensing efficiency.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to the improvement of a lens array in which a large number of microlenses are arranged one-dimensionally or two-dimensionally. Regarding the structure of a lens array.

[Prior Art] A lens array, in which a large number of microlenses are formed in an array on a transparent substrate such as glass or plastic, is rapidly becoming used in a wide range of fields such as image reading, recording, and display.

In particular, instead of forming a light refraction curved surface protruding from the substrate surface, the refractive index of the lens portion is made different from the refractive index of the substrate, and the lens surface on the substrate surface side is made a flat surface flush with the substrate. A flat plate lens array (hereinafter simply referred to as a "lens array"), in which the curved side is located within the thickness of the substrate, has the great advantage of being easy to combine and assemble with other optical components because the surface is flat. be.

In manufacturing the above lens array, the following method has conventionally been used.

First, a corrosion-resistant protective film (mask film) of Nl, Au, Cr, etc. is formed on the surface of the glass substrate by vapor deposition, sputtering, plating, etc., and a circular shape is formed on the lens position of this mask film using well-known photolithography technology. An opening is provided, and a glass etching solution such as a mixed solution of hydrofluoric acid, sulfuric acid, and nitric acid is brought into contact with the mask surface, and the glass is isotropically etched through the opening.

After etching treatment for a suitable period of time, a transparent material having a refractive index different from that of the glass substrate and generally having a higher refractive index than the substrate is deposited or filled in the resulting recessed portion having a semicircular cross section.

This filled opening acts as a lens.

[Problems to be Solved by the Invention] The conventional lens array manufactured by the method described above is
Even if the lenses are closely arranged in a staggered manner as shown in Figure (A), triangular non-lens portions 3 remain between adjacent lenses 2 in the lens array l.

The area ratio of this non-lens portion 3 is 9.3%.

In the square lattice arrangement as shown in FIG. 8(b), the area ratio of the non-lens portion 3 becomes 21.5%, which is a considerably large value.

When attempting to obtain a condensing point array using a lens array plate in an IA element, liquid crystal display panel, etc., in the conventional lens array structure, the incident light is
There was a problem in that 00% of the light was not collected, and the light collection efficiency was lowered by the above percentage.

[Means for solving the problem] On at least one side of a flat transparent substrate, a large number of recesses each having a curved bottom wall are arranged in a densely packed state in which they are bordered by polygonal ridge lines in plan view. A lens array was constructed by filling these recesses with a transparent material such as resin or glass having a refractive index different from that of the substrate.

The concave filling material forming the lens described above may be manufactured as an independent lens array plate by finishing the surface flatly, or when bonded to other parts such as a liquid crystal display panel,
It may also be used as an adhesive layer.

[Function] According to the present invention, the lenses forming the lens array are lined up in a polygonal repeating pattern without any gaps, and the non-lens portion 3 in conventional products is eliminated. Therefore, a light spot array can be obtained with almost 100% light collection efficiency.

[Example] The present invention will be described in detail below based on an example shown in the drawings.

FIG. 1 shows a general cross-sectional structure of a lens array according to the present invention, in which a concave portion 12 whose bottom wall surface 12A forms a smooth curved surface is formed on one side of a flat substrate 11 made of a transparent material such as glass or plastic. , are formed in large numbers by, for example, the chemical etching method described below.

This concave portion 12 has a boundary edge line 13 between adjacent concave portions that is generally a polygon of the same shape, such as a square lattice as shown in FIG. 2 or a /X lattice as shown in FIG. Formed to form a densely packed pattern.

Each of the concave portions 12 is filled with a transparent material +4 such as resin or glass having a refractive index higher than that of the substrate 11 to form each lens portion 10A of the lens array. That is, the curved bottom wall 12A of the recess becomes the light refracting surface of the lens. Thereafter, the entire surface is finished to be a flat surface, thereby obtaining a lens array 10.

Alternatively, after filling with a liquid transparent resin and leaving it in an uncured state, a predetermined mating member I, such as a liquid crystal display panel 20, is laminated and cured, as shown in Figure 4.

In this case, lens portion formation and adhesion can be performed at the same time.

In the example shown in FIG. 4, by adjusting the array pitch of the lens array IO to the pixel pitch of the liquid crystal display panel 20, the illumination light 30 is focused by each lens IOA of the lens array IO, and the illumination light 30 is focused on the liquid crystal display panel 20. Translucent window 21 of each pixel of the panel
The illumination light, which was blocked by the non-transparent portion 22 such as electrodes and TPT in conventional liquid crystal display panels, effectively contributes to the display, and an extremely high-definition image can be obtained.

Next, a preferred method for manufacturing the lens array according to the present invention will be described with reference to FIG.

First, by sputtering or vapor deposition on the surface of the glass substrate 11,
A protective coating film 8 is formed of a metal film such as Nl, Au, Cr, etc. that has corrosion resistance against etching solutions.

Next, the coating film 8 is formed by a well-known photolithography method.
A booth opening 9 is formed with a predetermined lens array arrangement butter 7. For example, in the case of a honeycomb type lens array as shown in FIG. 3, the apertures 9 are formed in a staggered arrangement as shown in FIG.

The shape of this opening 9 may be circular regardless of the planar shape of the lens to be finally obtained. Also, its diameter is made sufficiently smaller than the lens diameter.

Next, the coated glass substrate described above is chemically etched by immersing it in a glass etching solution such as a mixed solution of hydrofluoric acid, sulfuric acid, and hydrochloric acid. By this process, the surface of the glass substrate is isotropically etched starting from the opening 9 of the coating film, and a substantially hemispherical recess 12B as shown in FIG. 5(b) is obtained.

This first stage etching process is performed by etching the adjacent recess 12B.
It is stopped at O, leaving a flat boundary part 23 with a slight width in between.

Next, after removing the coating film 8 from the surface of the glass substrate, the entire surface of the glass substrate is etched. As a result of this second stage etching process, the bottom wall of the recess 12B becomes a gently curved surface as shown in FIG. Ridge line 1
It becomes 3. In other words, each polygon is the same in plan view (
In the case of a staggered arrangement, the recesses form a hexagonal shape, resulting in a densely packed arrangement in which adjacent recesses are in close contact with each other.

Note that since the initial recess 12B is circular, the width of the boundary between adjacent recesses is not uniform, but in the second stage etching described above, the widest boundary portion forms a ridge line 13 with a sharp upper end. Even if the etching is performed up to the maximum width, the narrowest boundary part will not disappear (as shown in FIG.
remains.

After the two-step etching process described above, the recess 12 is filled with a transparent material such as resin having a higher refractive index than the substrate glass.

The embodiments of the present invention shown in the drawings have been described above.
It goes without saying that various modifications other than the embodiments can be made.

For example, in the illustrated example, only a square lattice and a honeycomb are shown as patterns of the lens array, but the shape is not particularly limited, and may be a rectangle, a collection of regular pentagons and regular hexagons, or the like.

Further, the concave lens may be formed not only on one side of the substrate but also on both sides.

[Effects of the Invention] According to the present invention, light that was not focused by a conventional lens array and was transmitted as it is is effectively focused, and a light spot array can be obtained with almost perfect light focusing efficiency. . Therefore, performance superior to conventional lens arrays can be achieved when applied to solid-state image sensors and liquid crystal display devices.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing one embodiment of the present invention, FIG. 2 is a plan view showing an example of the pattern of the lens array of the present invention, and FIG.
The figure is a plan view showing another pattern example of the lens array of the present invention, Figure 4 is a sectional view showing an example of application of the lens array of the present invention, and Figures 5 (a) to 2) are lenses used in the present invention. 6 is a plan view showing an example of the etching mask pattern formed on the substrate glass by the manufacturing method shown in FIG. 5, and FIG. FIG. 8 is a cross-sectional view illustrating the shape of the concave boundary obtained by this method, and a plan view illustrating problems with the conventional lens array. 8... Etching protective film 9... Opening 10... Lens array 10A... Lens 11... Glass substrate 12... Concavity +3... Lens boundary ridge line 14... Transparent filling material 20... ...Liquid crystal display panel 21...Transparent window 22...Non-transparent part 30...Illumination light 1

Claims (1)

[Claims] A large number of recesses each having a curved bottom wall are arranged in a densely packed state on at least one side of a flat transparent substrate, and the recesses have a polygonal ridge line as a boundary when viewed from above, and these recesses have a refraction angle that is different from that of the substrate. A densely packed lens array made of transparent materials with different ratios.