JP2005019858A - Two-dimension image converting element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a two-dimension image converting element wherein any folding mechanism is not required, etc., and at the same time its thinning is achieved on the level nearly equal to its photographing element unit. <P>SOLUTION: The two-dimension image converting element 10 has a micro-lens array 1 wherein unit lenses having a honeycomb shape in their plan view are laid closely, a shading layer 2 having opening portions 2a which is provided on the optical axis of the micro-lens array 1 oppositely thereto, and a plane image photographing element 4 wherein a plurality of photoelectric converting elements 3 are arranged in the form of a square grid. Further, the element 10 is characterized in that a translucent substance is filled as a filling material 5 into the gap between the shading layer 2 and the plane image photographing element 4. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a two-dimensional image conversion element such as a video camera or a digital camera, and more particularly to a microlens image pickup element using a microlens.
[0002]
[Prior art]
A conventional two-dimensional image conversion element represented by a current CCD or the like is a light-electric conversion element that converts a light intensity distribution on the surface into an electric signal and takes it out as a two-dimensional element. An imaging optical system for obtaining the light intensity distribution shown is indispensable.
[0003]
A conventional digital imaging optical system will be briefly described. A conventional digital imaging device takes the form of a so-called photosensitive element array such as a CCD or a C-MOS, and the element itself is manufactured by a semiconductor process (for example, see Patent Document 1).
[0004]
[Patent Document 1]
Japanese Patent Laid-Open No. 05-152557
Such a digital imaging device itself is only as thin as a silicon wafer and is very thin, and the imaging optical system is mainly composed of a lens system whose thickness is about the same as the focal length of the lens. It is common to become.
FIG. 2 shows an example in which a triplet type is used as a conventional digital imaging optical system. In the figure, reference numeral 11 denotes a triplet lens composed of a convex lens / concave lens / convex lens, and reference numeral 14 denotes a planar imaging device.
In order to obtain a certain angle of view, the diagonal length and the focal length of the image sensor need only be approximately equal, and in this case, a slightly wide-angle lens configuration is obtained. Such a configuration is often adopted in a compact camera or the like.
At present, an imaging element having a diagonal length of about 1/2 inch to 1/3 inch is used, and therefore the thickness by the optical system is also about the same.
[0006]
This imaging optical system has the same basic structure as a photographic lens, etc., but it is necessary to arrange the lenses in the optical axis direction so that the light beam reaches the end of the image sensor. Therefore, the size in the direction of the optical axis is physically determined, and there are restrictions on the miniaturization, especially the thinness to the area of the image sensor, and it is easy to realize a thin configuration including the imaging optical system Difficult to do.
In addition, the method of thinning the lens part of the optical system as a folding type or a retractable type has been used for some time, but a mechanical mechanism that deploys these is required at the time of imaging, not only in terms of accuracy and cost, Even in terms of usability, there is a time lag until photographing becomes possible, which is not preferable.
[0007]
[Problems to be solved by the invention]
The main problem is to achieve a reduction in thickness at the same level as that of a single imaging device without requiring a folding mechanism.
[0008]
[Means for Solving the Problems]
As a result of conducting research and development on the above-mentioned problems in order to solve the above-mentioned problems, it has been found that the above-mentioned problems can be solved by using the following means.
According to a first aspect of the present invention, there is provided a lens array in which unit lenses having a honeycomb shape in plan view are laid without gaps, a light-shielding layer having an opening disposed relative to the optical axis of the lens array, and a square A two-dimensional image conversion element comprising a plurality of photoelectric conversion elements arranged in a lattice pattern, wherein the substance having translucency is provided in a gap between the light-shielding layer and the planar image pickup element. Is filled as a filler, and a two-dimensional image conversion element is provided.
[0009]
By providing a light shielding layer between the lens array and the planar imaging device, it is possible to prevent image blur due to image crosstalk and lens array aberration.
Further, unnecessary reflection can be prevented.
By adopting a honeycomb shape in a plan view, interference due to the periodic structure is reduced, and moire generated between the planar structure of the planar imaging element is reduced.
Furthermore, by having a filler in the gap between the light shielding layer and the planar imaging device, an improvement in image quality due to the refraction action is also expected. In particular, by using a solid filler, the mechanical strength is improved and the durability of the two-dimensional image conversion element is improved.
[0010]
The invention according to claim 2 provides a two-dimensional image conversion element, wherein the lens array and the light shielding layer are integrally formed.
[0011]
Since the lens array and the light shielding layer are integrally formed, the relative positions of the individual unit lenses constituting the lens array and the light shielding layer provided with an opening corresponding to the unit lens in the vicinity of the focal point thereof. The relationship can be fixed, and it becomes possible to improve the simplicity of manufacturing and the durability of these components (parts).
[0012]
According to a third aspect of the present invention, the focal position of the paraxial focal point of the unit lens is respectively on the planar imaging device in accordance with a change in condensing due to the refractive index of the lens array, the light shielding layer, and the filler. The two-dimensional image is characterized in that the shape of the unit lens is adjusted in advance so that the spherical aberration amount of the lens array is equal to or smaller than the size of the photoelectric conversion element arranged on the imaging element surface. A conversion element is provided.
[0013]
It is possible to improve the image quality by adjusting the shape of the unit lens, and by setting the spherical aberration amount of the lens array to be equal to or smaller than the size of the photoelectric conversion elements arranged on the image sensor surface, A good image can be obtained without being affected by the aberration of the.
Here, the “size” means an approximate lens diameter.
[0014]
According to a fourth aspect of the present invention, there is provided a first lens array in which unit lenses having a honeycomb shape in plan view are spread without gaps, and a unit lens having a honeycomb shape in plan view is spread without gaps, and the first lens array. A two-dimensional image conversion comprising: a second lens array configured so that its own optical axis coincides with the optical axis of the image sensor; and a planar imaging device having a plurality of photoelectric conversion elements arranged in a square lattice pattern. There is provided a two-dimensional image conversion element, wherein a gap between the second lens array and the planar imaging element is filled with a translucent substance as a filler.
[0015]
By having the second lens array, it becomes easy to correct the aberration of the unit lens and to further improve the image quality.
[0016]
The invention according to claim 5 provides a two-dimensional image conversion element characterized in that the first lens array and the second lens array are integrally formed.
[0017]
By integrating the first lens array and the second lens array, correct imaging conditions can be easily maintained, and the durability of components (parts) can be improved as the mechanical strength increases. It becomes possible to improve the property.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
A two-dimensional image conversion element according to the present invention will be described in detail with reference to FIG. Fig.1 (a) is a top view, FIG.1 (b) is a bb arrow directional cross-sectional view of (a).
A two-dimensional image conversion element 10 according to the present invention is configured with a microlens array (lens array) 1, a light shielding layer 2, a planar imaging element 4, and a filler 5 as main elements.
[0019]
The microlens array 1 has a plurality of unit lenses having a honeycomb shape in plan view, which are spread without gaps as shown in FIG.
The light shielding layer 2 has an opening 2 a that is disposed relative to the optical axis L of the microlens array 1.
The planar imaging element 4 has a plurality of photoelectric conversion elements 3 arranged in a square lattice pattern on one surface thereof.
The filler 5 is filled in a gap (space) between the light shielding layer 2 and the planar imaging element 4 and is made of a translucent substance.
[0020]
According to the two-dimensional image conversion element 10 of the present invention, a microlens array 1 having a focal point on the surface of the planar imaging element 4 and having a plurality of unit lenses arranged in an array covers an appropriate pixel area. And is configured to cover the entire imaging surface such as a CCD.
At this time, by inserting a light-shielding layer 2 serving as a diaphragm between the microlens array 1 and the planar imaging device 4, image crosstalk (a phenomenon that is mixed with an adjacent image) or aberration of the microlens array 1. Can prevent image blurring.
According to this configuration, a large number of small images are formed on one flat image pickup device 4, but the images can be reconstructed by a computer or the like and taken out as a single image.
[0021]
Further, by filling the space between the planar imaging device (CCD) 4 and the microlens array 1 with a translucent filler 5, for example, an organic material such as acrylic, glass, index matching oil, etc. Reflection (reflection caused by the difference in refractive index at the lens interface) can be prevented, and by using a solid substance, the amount of reflection itself is reduced (the difference in refractive index is reduced) and the mechanical rigidity is improved. , Can improve the reliability of the product.
Of course, air or vacuum may be used. In this case, it is convenient to reduce costs by reducing man-hours.
[0022]
Furthermore, when combining the planar imaging element 4 and the microlens array 1, since the planar view shape of the unit lens of the microlens array 1 is a honeycomb shape, interference due to the periodic structure is reduced. It becomes possible to reduce the occurrence of moiré.
Furthermore, the material of the microlens 1 or the filler 5 is not particularly limited as long as it is a light-transmitting material due to its characteristics. However, considering its productivity, durability, etc., it is a plastic type material. It is desirable to use a material.
[0023]
Examples of plastics include acrylic resins such as polymethyl methacrylate, polycarbonate, acrylic-styrene copolymers, styrene resins, and polyvinyl chloride.
Further, since fine processing with fine pitch can be performed, it is preferable to use a radiation curable resin such as an ultraviolet curable resin or an electron beam curable resin as the material of the lens layer.
As the radiation curable resin, for example, a composition in which a reaction diluent, a photopolymerization initiator, a photosensitizer, or the like is added to urethane (meth) acrylate and / or epoxy (meth) acrylate oligomer can be used. The urethane (meth) oligomer is not particularly limited, but for example, polyols such as ethylene glycol, 1,4 butanediol, neopentyl glycol, polycaprolactone polyol, polyester polyol, polycarbonate diol, and polytetramethylene glycol; It can be obtained by reacting with polyisocyanates such as hexamethylene diisocyanate, isophorone diisocyanate, tolylene diisocyanate and xylene isocyanate.
[0024]
Although it does not specifically limit as an epoxy (meth) acrylate oligomer, For example, the terminal glycidyl ether of a bisphenol A type epoxy resin, a bisphenol F type epoxy resin, a phenol novolacic type epoxy resin, a bisphenol A type propylene oxide adduct It can be obtained by reacting epoxy resins such as fluorene epoxy resin with (meth) acrylic acid.
The example given here is only an example, and does not limit these shapes.
[0025]
In the present embodiment, it is more preferable that the microlens array 1 and the light shielding layer 2 are configured so as to be integrated, for example, in a sheet shape or a film shape.
[0026]
Further, the unit lens is previously set so that the focal position of the paraxial focal point of the unit lens is on the planar imaging device 4 in accordance with the change in the light collection due to the refractive index of the microlens array 1, the light shielding layer 2, and the filler 5. It is more preferable that the spherical aberration amount of the microlens array 1 is less than or equal to the spherical aberration amount of the photoelectric conversion elements arranged on the imaging element surface.
[0027]
The present invention is not limited to the embodiment described above, and the first lens array in which unit lenses having a plan view honeycomb shape are spread without gaps, and the unit lenses having a plan view honeycomb shape. And a plurality of photoelectric conversion elements arranged in a square lattice, and a second lens array configured so that its optical axis coincides with the optical axis of the first lens array. And a planar imaging element having a light-transmitting substance filled in a gap between the second lens array and the planar imaging element.
[0028]
In this case, it is more preferable that the first lens array and the second lens array are integrally formed.
[0029]
【The invention's effect】
By using the two-dimensional image conversion element according to the present invention, it is possible to obtain an image pickup element that can obtain a sufficient image with a thin structure that has not been obtained so far, and since there are few movable parts and the mechanical structure can be simplified, it is very reliable. A highly functional device can be realized.
Further, the occurrence of moire due to the array structure can be suppressed by making the shape of the unit lens of the microlens array in plan view a honeycomb shape.
[0030]
Due to the effects as described above, for example, a new application such as mounting a digital camera on an IC card is opened, and as a result, an inexpensive and high-performance thin digital image sensor can be provided.
[Brief description of the drawings]
1A and 1B are diagrams showing an embodiment of a two-dimensional image conversion element according to the present invention, in which FIG. 1A is a plan view and FIG. 1B is a cross-sectional view taken along line bb in FIG.
FIG. 2 is a conceptual diagram of a conventional digital imaging optical system.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Micro lens array 2 Light-shielding layer 2a Opening part 3 Photoelectric conversion element 4 Planar image sensor 5 Filler 10 Two-dimensional image conversion element

Claims (5)

A lens array in which unit lenses having a honeycomb shape in plan view are spread without gaps;
A light shielding layer having an opening disposed relative to the optical axis of the lens array;
A two-dimensional image conversion device comprising a planar imaging device having a plurality of photoelectric conversion devices arranged in a square lattice,
A two-dimensional image conversion element, wherein a light-transmitting substance is filled in a gap between the light shielding layer and the planar imaging element as a filler. The two-dimensional image conversion element according to claim 1, wherein the lens array and the light shielding layer are integrally formed. The shape of the unit lens is previously set so that the focal position of the paraxial focal point of the unit lens is on the planar imaging device in accordance with the change in the light collection due to the refractive index of the lens array, the light shielding layer, and the filler. 3. The two-dimensional image conversion according to claim 1, wherein a spherical aberration amount of the lens array is equal to or smaller than a size of a photoelectric conversion element arranged on an image pickup element surface. element. A first lens array in which unit lenses having a honeycomb shape in plan view are laid without gaps;
A second lens array configured such that unit lenses having a honeycomb shape in plan view are spread without gaps, and the optical axis of the unit lens coincides with the optical axis of the first lens array;
A two-dimensional image conversion device comprising a planar imaging device having a plurality of photoelectric conversion devices arranged in a square lattice,
A two-dimensional image conversion element, wherein a gap between the second lens array and the planar imaging element is filled with a translucent substance as a filler. The two-dimensional image conversion element according to claim 4, wherein the first lens array and the second lens array are integrally formed.

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