JPH11317836A - Optical waveguide type reduction optical image sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical waveguide type reduced optical image sensor which can improve resolution without reducing the diameter of a microlens and which does not reduce black and white contrast even if the resolution is increased. . SOLUTION: The microlens array 1 provided at an equal pitch corresponding to the number of pixels and the microlens array 1 provided at an optical waveguide substrate 3 and provided at an equal pitch corresponding to the number of pixels. And a CCD linear sensor 6 for converting light incident from the optical waveguide array 4 into an electric signal. Then, the pair of the microlens array 1 and the optical waveguide array 4 is formed in a laminated structure, and the pair of the microlens 2 and the optical waveguide 5 in the layer adjacent to each other in the laminating direction is shifted by one pitch in the array direction. The pair of the microlens 2 and the optical waveguide 5 adjacent in the array direction reads pixels adjacent several layers.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-resolution optical waveguide type reduced optical image sensor using an optical waveguide.

[0002]

2. Description of the Related Art As shown in FIG. 15, a conventional optical waveguide type reduced optical image sensor is provided on a microlens array 1A arranged at equal pitches corresponding to the number of pixels and on an optical waveguide substrate 3A. And an optical waveguide array 4A for transmitting light collected by the microlens array 1A and a CC for converting light incident from the optical waveguide array 4A into an electric signal.
And a D linear sensor 6A (photoelectric conversion element).
This optical waveguide type reduction optical image sensor is configured such that an image read by the microlens array 1A is reduced through the optical waveguide 5A and is introduced into the CCD linear sensor 6A. It is characterized in that the device can be made smaller than the conventional image sensor (see Japanese Patent Application Laid-Open No. 7-301730).

FIG. 17 is an explanatory diagram showing a state of transmission of an optical signal from a document to the optical waveguide 5A when reading a monochrome document using the optical waveguide type reduced optical image sensor. In the conventional optical waveguide type reduced optical image sensor, as shown in the figure, the distance between the original and the microlens 2B of the microlens array 1A and the distance between the microlens 2B and the optical waveguide 5A of the optical waveguide array 4A are adjusted. By adjusting the size of the image 8 of the predetermined pixel 7A on the original to the size of the end face of the optical waveguide 5A, it is possible to prevent the adjacent pixels 9 from entering the corresponding optical waveguide 5A. Further, by adjusting the numerical aperture NA of the microlens 2B and the optical waveguide 5A, the adjacent microlens 2B can be formed.
It is also possible to prevent the light collected from B from entering the optical waveguide 5A.

FIG. 16 shows another conventional optical waveguide type reduction optical image sensor in which the pitch of the microlenses 2B is halved with the same reading width and the resolution is doubled. FIG. 15 and FIG. 16 are conceptual explanatory diagrams, each showing a microlens 2B, an optical waveguide 5A, and a CC.
As for the number of D linear sensors 6A, it is assumed that there is one corresponding to the resolution.

[0005]

Since the conventional optical waveguide type reduced optical image sensor is configured as described above, as apparent from a comparison between FIG. 15 and FIG. The diameter of the microlens 2B corresponding to 7A is halved, and as a result, the intensity of the optical signal transmitted to the optical waveguide 5A is reduced to ４. That is, this method has a problem that when the resolution is improved, the black and white contrast is greatly reduced.

Accordingly, the present invention has been made to solve the above-mentioned problem, and it is possible to improve the resolution without reducing the diameter of the microlens. Even if the resolution is increased, the black and white contrast is reduced. It is an object of the present invention to provide an optical waveguide type reduced optical image sensor without any problem.

[0007]

In order to achieve the above-mentioned object, according to the present invention, a microlens array arranged at equal pitches to a number corresponding to the number of pixels and an optical waveguide substrate are provided. And an optical waveguide array for transmitting the light condensed by the microlens array and a photoelectric conversion for converting the light incident from the optical waveguide array into an electric signal. A pair of the microlens array and the optical waveguide array is formed in a laminated structure, and the pair of the microlens and the optical waveguide of the layer adjacent in the laminating direction is shifted by one pitch in the array direction. The pair of the microlens and the optical waveguide adjacent to each other in the array direction reads pixels adjacent to each other by several layers.

With such a configuration, an array of a pair of microlenses and optical waveguides corresponding to one pixel is formed in a layered structure, and adjacent microlenses and optical waveguides are shifted in the array direction by one pitch in the array direction. Microlenses adjacent in the array direction can read pixels of a read document or the like separated by several pitches of layers. Therefore, the resolution can be improved without reducing the diameter of the microlens.

Further, the microlenses corresponding to the respective optical waveguides are arranged such that the optical axes of the microlenses are shifted from the corresponding optical waveguides so that all the optical waveguides of each layer read pixels on one line. can do. With this configuration, if the optical axes of the microlens and the optical waveguide are adjusted so that all the layers read pixels on one line, signal processing and the like become easy.

According to a third aspect of the present invention, there is provided a microlens array arranged at a constant pitch corresponding to the number of pixels, and a microlens array provided at an optical waveguide substrate at a constant pitch corresponding to the number of pixels. An optical waveguide array for transmitting light collected by the microlens array, and a photoelectric conversion element for converting light incident from the optical waveguide array into an electric signal; A pair of waveguide arrays is configured in a laminated structure, and optical waveguides of layers adjacent to each other in the laminating direction are arranged in a direction substantially orthogonal to the array direction, and the optical axes of the optical waveguides and the microlenses are shifted to each other in the array direction. The microlens so that the adjacent pair of the microlens and the optical waveguide reads pixels adjacent to several layers, and each optical waveguide of each layer reads pixels on one line. Characterized in that the placed.

With such a configuration, when the optical waveguides are arranged in a direction substantially orthogonal to the array direction, the optical axis of the microlens is shifted, and the same operation and effect as described above can be expected.

Further, the invention according to claim 4 is characterized in that the microlens array arranged at equal pitches to the number corresponding to the number of pixels and the microlens array provided to the optical waveguide substrate at equal pitches to the number corresponding to the number of pixels. An optical waveguide array for transmitting light collected by the microlens array, and a photoelectric conversion element for converting light incident from the optical waveguide array into an electric signal; A pair of waveguide arrays is configured in a laminated structure, microlenses of layers adjacent in the laminating direction are arranged in a direction substantially orthogonal to the array direction, and the optical axes of the optical waveguide and the microlenses are shifted to each other in the array direction. The optical waveguide such that adjacent pairs of the microlens and the optical waveguide read pixels adjacent to each other by several layers, and each optical waveguide of each layer reads pixels on one line. Characterized in that the placed.

With such a configuration, when the microlenses are arranged in a direction substantially perpendicular to the array direction, the optical axis of the optical waveguide is shifted, and the same operation and effect as described above can be expected.

According to the fifth aspect of the present invention, a pair of a microlens and an optical waveguide adjacent to each other in the array direction reads pixels separated by several pitches, and all layers read pixels on one line. In any of claims 2 to 4, the microlens array is provided within a range of the divergence angle corresponding to the numerical aperture of the optical waveguide while the center of the radius of curvature is fixed without changing the diameter of the microlens. In addition, it is possible to reduce the coupling loss due to a shift in the numerical aperture between the microlens and the optical waveguide.

It is possible to provide the microlens array arranged in a range of a divergence angle corresponding to a numerical aperture of the optical waveguide while keeping a center of a radius of curvature fixed without changing a diameter of the microlens.

Here, the laminating direction of the above-mentioned "microlens array and optical waveguide array" may be any of up, down, front, rear, right and left directions. The number of layers may be two or more.
Therefore, the resolution may be tripled with three layers,
Four or more layers may be used. In this case, the optical waveguide array can be formed in a layered structure by producing and stacking the optical waveguide arrays layer by layer. The method of manufacturing the optical waveguide array in this case is not particularly limited.For example, a lower clad, a core, and a resist are applied on an optical waveguide substrate having a copper thin film formed on one surface by using a spin coating method. The core ridge is processed by photolithography and reactive ion etching using oxygen gas, the resist is peeled off, the upper clad is applied using a spin coating method, and then the thin optical waveguide on the film is peeled off with hydrochloric acid. Just do it.

Although the photoelectric conversion element is not particularly limited, for example, a CCD linear sensor, a CMOS sensor, a bipolar, or the like can be appropriately used. Further, the term “substantially orthogonal” includes both the strict sense of orthogonal and the degree of orthogonality that is regarded as approximately orthogonal. The optical waveguide type reduced optical image sensor according to the present invention is used as a scanner or the like.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to the following embodiments. In addition, the following figures are conceptual only. For example, the numbers of the microlenses 2, the optical waveguides 5, and the CCD linear sensors 6 as photoelectric conversion elements shown in FIG. Shall be.

As shown in FIG. 1, the optical waveguide type reduced optical image sensor according to the present embodiment converts an optical signal collected by the microlens 2 of the microlens array 1 into an optical waveguide of the optical waveguide array 4 on the optical waveguide substrate 3. C by 5
It is configured to transmit to the CD linear sensor 6.

The microlens array 1 is made of polymethyl methacrylate (= polymethyl methacrylate, hereinafter referred to as PMMA) having excellent mechanical strength, light resistance, and transparency.
(Abbreviated as “abbreviated”) as a material, and injection molded. As a mold, a radius of 1
A stamped 25 μm ruby ball is used. The microlens array 1 includes a plurality of aligned microlenses 2, and the plurality of microlenses 2
Each of the plurality of optical waveguides 5 has a pitch of 25 μm.

Each micro lens 2 is a spherical lens having a diameter of 125 μm, and has a radius of curvature of 130 μm (± 5 μm).
μm). The distance from each micro lens 2 to the optical waveguide 5 is set to about 400 μm. This is because the distance between the document and the microlens 2 is set to 3.5 mm.

The optical waveguide array 4 has a laminated structure. In the embodiment described below, a case is described as an example where the optical waveguide array 4 has a two-layer laminated structure parallel to the upper and lower surfaces of the optical waveguide substrate.
The lamination direction of the optical waveguide array may be any of up, down, front, rear, right and left directions, and the number of laminations may be any number as long as it is two or more.

The distance between the optical waveguide arrays 4 is 500 μm
Is set to The optical waveguide substrate 3 has a length of 220 m.
m, a width of 20 mm, and a thickness of 1 mm. The optical waveguide 5 is made of PMMA and has a length of 8 μm.
m, 8 μm in width. This optical waveguide 5
Are arranged at a pitch of 125 μm at one end of the microlens 2 and at a pitch of 14 μm at the other end of the CCD linear sensor 6. The optical waveguide 5 is provided with a groove to be a horizontal portion below the clad of the above-described size in the injection molded substrate,
After filling the core with an ultraviolet curable resin, the core is coated with an upper clad by irradiating ultraviolet rays.

Further, the CCD linear sensor 6 is provided at the center of the other end of the optical waveguide substrate 3. The CCD linear sensor 6 includes a light receiving portion having a pitch of 14 μm. The light receiving portions are arranged in a number corresponding to the number of the optical waveguides 5 and provided with lines in the number of layers.

<First Embodiment> A first embodiment will be described with reference to FIGS. As shown in FIG. 2, the microlens array 1 includes a plurality of aligned microlenses 2, and the plurality of microlenses 2 includes 12 microlenses.
Molded so as to correspond to each of the plurality of optical waveguides 5 at a pitch of 5 μm and have the same optical axis as the optical waveguides 5, and
A laminated structure composed of two layers is formed in parallel with the upper and lower surfaces of the optical waveguide substrate 3. Further, the pair of the microlens 2 and the optical waveguide 5 constituting the pair of the microlens array 1 and the optical waveguide array 4 is formed so as to be shifted by ピ ッ チ pitch in the array direction between two vertically stacked layers. Have been.

FIG. 3 shows a state in which the optical waveguides 5 constituting the optical waveguide array 4 are formed so as to be shifted by a half pitch in the array direction between two vertically stacked layers. FIG. 3 is a front view of a substrate 3.

FIG. 4 shows two microlenses 2 and the optical waveguide 5 which are closest to each other in the laminating direction of the microlens array 1 and the optical waveguide array 4 stacked in two layers. As described above, the two pairs of microlenses 2 and the optical waveguide are actually formed so as to be shifted by a half pitch in the array direction (see FIG. 2). In such a configuration, a pair of the microlens 2 and the optical waveguide 5 adjacent in the array direction reads several adjacent pixels, and the upper and lower pixels thus read are superimposed on one layer. Thus, the gap between the pixels 7 read by the upper optical waveguide array 4 is filled with the pixels 7 read by the lower optical waveguide array 4.

In such a configuration, read image signals are stored in an external memory or the like, and output timing is adjusted before forming output pixels. As a result, it is not necessary to reduce the diameter of the microlens 2, and it is possible to double the resolution without reducing the intensity of the optical signal.

In the present embodiment, the microlens array 1 and the optical waveguide array 4 have a two-layer structure, but the number of layers may be any number as long as the number is two or more. As you did. In this case, the pair of the microlens 2 and the optical waveguide 5 of the layer adjacent in the stacking direction is
By shifting in the array direction by a pitch equal to the number of layers,
A pair of the microlens 2 and the optical waveguide 5 adjacent in the array direction reads pixels adjacent to each other by several layers. Thus, as in the case of the two-layer stack, the resolution can be improved by the number of layers without reducing the black and white contrast.

<Second Embodiment> Next, a second embodiment of the present invention will be described with reference to FIGS. The optical waveguide type reduction optical image sensor according to the present embodiment has a structure shown in FIG.
As shown in FIG. 6, the structure is basically the same as that of the first embodiment, but the upper and lower layers are on the same line by shifting the optical axis of the microlens 2 and the optical waveguide 5 in the stacking direction. It is adjusted so that the pixels 7 are read alternately. FIG.
The state where the optical axes of the microlens 2 and the optical waveguide 5 coincide with each other is represented by the microlens 2, and the light between the microlens 2 and the optical waveguide 5 is read so that the upper and lower layers read the pixels 7 on the same line. The state where the axis is shifted is represented by the microlens 2A.

In this case, the micro lens 2 and the optical waveguide 5
By displacing the optical axes of the microlenses 2A and disposing them like the microlenses 2A, there is a concern about an increase in coupling loss due to a shift in the numerical aperture NA. FIG. 7 shows the result of measuring the lateral shift dependency of the coupling loss between the microlens 2 and the optical waveguide 5 according to the present embodiment. From FIG. 7, it can be seen that the tolerance at which the coupling loss increases by 0.5 dB is about 20 μm. Since the distance between the optical waveguide arrays 4 is 500 μm, the distance from the center is 250 μm.
μm. Since the displacement of 250 μm at the document position is within 20 μm on the image forming surface, the micro lens 2
Is considered negligible, considering that the incident light intensity is reduced by about 6 dB by halving the diameter of.

In this embodiment, the same operation and effect as those of the above embodiment can be expected. In addition, since the reading of the original is the same for all the arrays, the read image signals are stored in an external memory or the like to adjust the output timing. There is no need to perform this, and the reading speed can be greatly improved.

Third Embodiment A third embodiment of the present invention will be described with reference to FIGS. In this embodiment, as shown in FIG. 9, two optical waveguides 5 of two optical waveguide arrays 4 stacked vertically are arranged in a direction substantially orthogonal to the array direction. On the other hand, as shown in FIG. 10, two microlens arrays 1 are vertically stacked so that the microlenses 2 are arranged with the optical axis shifted from the optical waveguide 5. FIG. 8 is a view of such a structure as viewed from above the optical waveguide substrate 3. As apparent from FIG. 8, the pair of the microlens 2 and the optical waveguide 5 adjacent in the array direction reads two adjacent pixels, and the two-layer optical waveguide array 4 reads the pixel 7 on one line. It is possible to

In the present embodiment, the microlens array 1 and the optical waveguide array 4 have a two-layer laminated structure. However, similarly to the first embodiment, the microlens array 1 and the optical waveguide array 4 are not limited to two layers, but may be arranged in the array direction. The resolution can be improved by the number of layers without reducing the black-and-white contrast by making the pair of the microlens 2 and the optical waveguide 5 adjacent to each other read pixels adjacent to each other by several layers.

<Fourth Embodiment> In this embodiment, the arrangement of the microlens array 1 and the optical waveguide array 4 is opposite to that of the third embodiment. That is, the two microlenses 2 of the microlens array 1 vertically stacked are arranged in a direction substantially orthogonal to the array direction, as shown in FIG. The optical waveguide 5 is, as shown in FIG.
The microlens array 1 is arranged with the optical axis shifted from the microlens 2.

In such an arrangement, as in the third embodiment, the microlenses 2 adjacent in the array direction are arranged.
And the optical waveguide 5 read pixels adjacent to each other by several layers, so that the resolution can be improved by the number of layers without reducing the black-and-white contrast.

<Fifth Embodiment> Next, a fifth embodiment of the present invention will be described with reference to FIGS. In the optical waveguide type reduced optical image sensor according to the second embodiment, the coupling loss is increased, although it is only about 0.5 dB. Therefore, in the present embodiment, FIG.
As shown in FIG. 6, the center of the radius of curvature is the same as that of the microlens 2A of FIG.
The microlens array 1 installed in the range of the divergence angle corresponding to A is used.

The microlenses 2A of the microlens array 1 can be manufactured very easily by tilting the aluminum substrate when stamping a ruby ball.
The other parts are the same as those of the above-described embodiment, and the description will not be repeated.

In this embodiment, the same operation and effect as those of the above embodiment can be expected. Further, it is possible to prevent an increase in crosstalk and an increase in coupling efficiency due to a shift in the numerical aperture NA between the microlens 2A and the optical waveguide 5. Will be possible.

[0040]

As described above, according to the present invention, the resolution can be improved without reducing the diameter of the microlens. Further, it is possible to provide an optical waveguide type reduced optical image sensor in which the black and white contrast is not reduced even when the resolution is increased.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an embodiment of an optical waveguide type reduction optical image sensor.

FIG. 2 is an explanatory view showing a first embodiment of an optical waveguide type reduction optical image sensor.

FIG. 3 is an explanatory diagram showing an optical waveguide array in the first embodiment of the optical waveguide type reduced optical image sensor.

FIG. 4 is an explanatory diagram of a reading method in the first embodiment of the optical waveguide type reduced optical image sensor.

FIG. 5 is an explanatory diagram of a reading method in a second embodiment of the optical waveguide type reduced optical image sensor.

FIG. 6 is an explanatory diagram showing a state where light is condensed on an optical waveguide by a microlens according to a second embodiment of the optical waveguide type reduced optical image sensor.

FIG. 7 is a graph showing a change in coupling loss due to an axis shift between a microlens and an optical waveguide in a second embodiment of the optical waveguide type reduced optical image sensor.

FIG. 8 is an explanatory diagram of a reading method in a third embodiment of the optical waveguide type reduced optical image sensor.

FIG. 9 is an explanatory diagram showing an optical waveguide array in a third embodiment of the optical waveguide type reduced optical image sensor.

FIG. 10 is an explanatory diagram showing a microlens array in a third embodiment of the optical waveguide type reduced optical image sensor.

FIG. 11 is an explanatory diagram showing an optical waveguide array according to a fourth embodiment of the optical waveguide type reduced optical image sensor.

FIG. 12 is an explanatory diagram showing a microlens array according to a fourth embodiment of the optical waveguide type reduced optical image sensor.

FIG. 13 is an explanatory diagram of a reading method in a fifth embodiment of the optical waveguide type reduced optical image sensor.

FIG. 14 is an explanatory diagram showing a state where light is condensed on an optical waveguide by a microlens in a fifth embodiment of the optical waveguide type reduced optical image sensor.

FIG. 15 is a perspective view showing a conventional low-resolution optical waveguide type reduced optical image sensor.

FIG. 16 is a perspective view showing a conventional low-resolution optical waveguide type reduced optical image sensor.

FIG. 17 is an explanatory diagram of a reading method of a conventional low-resolution optical waveguide type reduced optical image sensor.

[Explanation of symbols]

 Reference Signs List 1 microlens array 2, 2A microlens 3 optical waveguide substrate 4 optical waveguide array 5 optical waveguide 6 CCD linear sensor (photoelectric conversion element) 7 pixel 8 imaging 9 adjacent pixel

Claims (5)

[Claims] 1. A microlens array provided at an equal pitch corresponding to the number of pixels, and a microlens array provided at an optical waveguide substrate and provided at an equal pitch corresponding to the number of pixels. An optical waveguide array for transmitting the light condensed by the optical waveguide array, and a photoelectric conversion element for converting light incident from the optical waveguide array into an electric signal, wherein a pair of the microlens array and the optical waveguide array is laminated. And the pairs of the microlenses and the optical waveguides of the layers adjacent in the laminating direction are shifted by the pitch of the number of layers in the array direction, and the pairs of the microlenses and the optical waveguides adjacent in the array direction are several layers. An optical waveguide-type reduced optical image sensor, wherein adjacent pixels are read. 2. The microlens array corresponding to each of the optical waveguides is arranged such that the optical axis is shifted with respect to the corresponding optical waveguide so that each optical waveguide of each layer reads pixels on one line. 2. The optical waveguide type reduced optical image sensor according to claim 1, wherein: 3. The microlens array provided on the optical waveguide substrate at a constant pitch corresponding to the number of pixels, and the microlens array provided on the optical waveguide substrate at a constant pitch corresponding to the number of pixels. An optical waveguide array for transmitting the light condensed by the optical waveguide array, and a photoelectric conversion element for converting light incident from the optical waveguide array into an electric signal, wherein a pair of the microlens array and the optical waveguide array is laminated. The optical waveguides of the layers adjacent to each other in the stacking direction are arranged in a direction substantially perpendicular to the array direction, and the optical axes of the optical waveguides and the microlenses are shifted, so that the microlenses adjacent to the array direction and the microlenses are aligned. The microlens is arranged so that a pair of optical waveguides reads pixels adjacent to several layers, and each optical waveguide of each layer reads pixels on one line. Waveguide-type reduced optical image sensor. 4. A microlens array provided at an equal pitch corresponding to the number of pixels and a microlens array provided at an optical waveguide substrate and provided at an equal pitch corresponding to the number of pixels. An optical waveguide array that transmits the light condensed in, and a photoelectric conversion element that converts light incident from the optical waveguide array into an electric signal, wherein a pair of the microlens array and the optical waveguide array is formed in a laminated structure. And by arranging the microlenses of the layers adjacent to each other in the stacking direction in a direction substantially orthogonal to the array direction, and displacing the optical axes of the optical waveguide and the microlenses
The pair of the microlens and the optical waveguide adjacent to each other in the array direction reads pixels adjacent to each other by several layers, and the optical waveguides are arranged such that each optical waveguide of each layer reads pixels on one line. Characteristic optical waveguide type reduced optical image sensor. 5. The microlens array according to claim 1, wherein the microlens array is arranged in a range of a divergence angle corresponding to a numerical aperture of the optical waveguide while a center of a radius of curvature is fixed without changing a diameter of the microlens. An optical waveguide type reduced optical image sensor according to claim 2.