JP2000292739A - Lens array assembly and optical device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a bright erect unmagnified image and to enhance the degree of freedom in selecting conjugate length or the depth of focus by forming plural lens parts and holder parts by the integral molding of resin. SOLUTION: This lens array assembly 1 is constituted by combining a 1st lens array 10 and a 2nd lens array 20 in a laminated state. The respective lens arrays 10 and 20 are equipped with plural lens parts 11 and 21 arrayed at an equal interval at the same pitch in a longitudinal direction and the holder parts 12 and 22 connecting the lens parts 11 and 21. The lens parts 11 and 21 and the holder parts 12 and 22 connecting them are formed by the integral molding of resin, whereby they are obtained by simple metallic-mold molding using transparent resin. The characteristic of the lens parts 11 and 21 is freely changed to set the conjugate length and the depth of focus. Furthermore, the lens diameter of the lens part of the lens array on an emission side is set to be larger than that on an incident side, so that brightness is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lens array assembly and an optical device using the same. More specifically, for example, in an optical device such as a contact type image sensor, an erect equal-magnification image of an image on a reading line is formed. The present invention relates to a lens array assembly used for, for example, forming an image on a light receiving element arranged in a line, and an optical device using the same.

[0002]

2. Description of the Related Art In a contact type image sensor, a lens used for obtaining an erect equal-magnification image is called a so-called selfoc lens array, and has a structure as shown in FIGS. . In other words, the lens array 9 has a black resin holder in which a plurality of rod lenses (Selfoc lenses) 91 having unique optical characteristics are arranged in parallel in a direction perpendicular to the optical axis with their optical axes aligned. 90. Each rod lens 91 has a flat surface corresponding to one surface 90a and the other surface 90b of the holder 90, both of the incident surface 91a and the outgoing surface 91b, so that the refractive index increases radially outward. It is different. This rod lens 91 is shown in FIG.
As a result, the optical path can be meandered, so that an erect equal-size image a ′ → b ′ of the object a → b can be obtained. Note that the distance H ₀ in the optical axis direction of the lens from the object a → b to the erect equal-magnification image a ′ → b ′ is called a conjugate length, and is defined by the conjugate length H ₀ when forming a contact image sensor. The original reading surface 33 and the light receiving surface 36 of the image sensor chip need to be disposed at a position at a fixed distance on the incident side and a position at a fixed distance on the emission side from the SELFOC lens array 9.

[0003]

The above-mentioned selfoc lens array must firstly have a unique optical characteristic that the rod lens provided therein has a different refractive index at various points inside the rod lens. However, it can be manufactured only by a person having a special manufacturing technique, and is therefore very expensive. This hinders the cost reduction of optical equipment such as a facsimile or an image reader having a contact image sensor or the like.

Secondly, the only way to change the conjugate length and depth of focus of the selfoc lens array is to change the optical characteristics of the selfoc lens itself. As a result, the degree of freedom in designing an optical device using the selfoc lens array is reduced.

Third, each SELFOC lens constituting the SELFOC lens array has a constant diameter from the entrance surface to the exit surface. In particular, when the lens length is increased to increase the depth of focus, a black resin is used. There is a problem in that more light is wasted as it is absorbed by the holder made of glass, and the image to be formed must be dark. This is a major cause of deteriorating the reading performance of the image sensor.

The present invention has been conceived under such circumstances, and can be manufactured at a significantly lower cost as compared with the conventional SELFOC lens array, and can provide a bright erect 1: 1 image. It is an object of the present invention to provide a lens array assembly that can be obtained and can increase the degree of freedom in selecting a conjugate length and a depth of focus.

[0007]

DISCLOSURE OF THE INVENTION In order to solve the above problems, the present invention employs the following technical means.

That is, in the lens array assembly provided by the first aspect of the present invention, a plurality of lens units arranged in parallel and a holder unit for integrally connecting these lens units are formed by integral resin molding. A lens array assembly comprising a plurality of lens arrays, each lens array being stacked so that the optical axis of each lens portion thereof is aligned, and combined so as to obtain an erect equal-magnification image. The lens diameter of the lens section of the lens array on the exit side is set to be larger than the lens diameter of the lens section of the lens array on the entrance side.

Each lens portion of each lens array is usually formed as a convex lens having both an entrance surface and an exit surface in a convex curved shape. When two lens arrays are combined, two convex lens units are arranged in series on each optical axis. Light passes through the convex lens portion of the first lens array and then passes through the convex lens portion of the second lens array. Here, the entrance surface of the convex lens portion of the first lens array is referred to as a first surface, the exit surface is referred to as a second surface, the entrance surface of the convex lens portion of the second lens array is referred to as a third surface, and the exit surface is referred to as a fourth surface. And In FIG. 5, light that has departed from a certain starting point S on the incident side is a first surface 11a.
A primary focus is formed near the second surface 11b and the third surface 21a by the refraction at. Second surface 11b and third surface 2
Since 1a is an opposing convex curved surface, light is bent so as to return to the starting point direction as viewed from the optical axis direction due to refraction when emitted from the second surface 11b and incident on the third surface 21a. Then, the light from the primary focal point is focused at a point R on the exit side by refraction on the fourth surface 21b. By the plurality of convex lens portions having the optical axes aligned in this way, a phenomenon equivalent to the meandering phenomenon of light observed in the SELFOC lens is obtained, and an erect life-size image of an object at a predetermined distance on the incident side of the lens array assembly is obtained. Is formed at a position at a predetermined distance on the emission side.

In the lens array assembly according to the present invention, each lens array is formed by integrally forming a lens portion, usually composed of a convex lens, and a holder portion connecting these lens portions with a resin. As described above, there is no need for a difficult configuration such as making the refractive index different in each part of the lens, and the lens can be obtained by simple molding using a transparent resin. The conjugate length and the depth of focus can be set by freely changing the characteristics of each lens unit.

In the lens array assembly according to the first aspect of the present invention, the lens diameter of the lens portion of the lens array on the emission side is set to be larger than the lens diameter of the lens portion of the lens array on the incidence side. I have. Such a configuration can be easily achieved by integrally molding the lens portion and the holder portion with the resin as described above. With such a configuration, the cross-sectional area of the light guide path until the light incident on the lens portion of the first lens array exits from the lens portion of the final lens array located on the exit side gradually increases. The rate at which light passing through the light guide path escapes or is absorbed by the holder decreases, and as a result, the brightness of the erecting equal-magnification image is increased. This leads to more reliable reading of an image by the light receiving element when this lens array assembly is used, for example, in a contact type image sensor, and greatly contributes to improving the performance of this type of image sensor. .

In a preferred embodiment, at least the first lens array on the emission side is provided with means for preventing crosstalk between adjacent lens units.
Therefore, it is possible to appropriately prevent image deterioration due to light entering a certain lens unit being mixed into an adjacent lens unit. When two lens arrays are combined, only the first lens array on the incident side is provided with a means for optically separating each lens unit as described above, and the second lens array is provided with such an optical unit. It has been confirmed that image degradation due to crosstalk can be sufficiently prevented without providing any separation means.

In a preferred embodiment, the means for optically separating the lens parts includes a groove provided between each adjacent lens part in the holder part. Since the grooves can be formed at the same time when the lens array is formed, the number of steps and components does not increase.

In a preferred embodiment, the groove is formed in a bottomed shape so as to be immersed at a predetermined depth from the entrance side or the exit side. With this configuration, since one surface of the lens array is connected, its strength is secured, and in the case of resin molding, the bottomed hole is easier to mold than the through hole.

[0015] In a preferred embodiment, the inner surface of the groove is covered with a black-colored or light-colored light-shielding material close to black. For example, it is conceivable to form a dark-colored coating film on the inner surface of the groove or to fill the groove with a dark-colored member. In this way, the light leaking laterally from the lens portion is absorbed by the light shielding material, and the light is more reliably prevented from entering the adjacent lens portion as crosstalk.

Further, in a preferred embodiment, the means for optically separating the lens portions includes a black color or a dark color close to the black color which covers an area surrounding the lens portion on the incident side surface and / or the exit side surface of the holder portion. The system further includes a light shielding material. With this configuration, the grooves are provided between the lens portions as described above to prevent light from migrating between the lens portions, and light is introduced into the lens array from a surface other than the entrance surface of the lens portions. Is incident, and the light in the lens array is prevented from being emitted from a surface other than the emission surface of the lens portion, so that the above-described crosstalk prevention effect is further enhanced.

In a preferred embodiment, the exit-side lens surface of the lens section of the exit-side lens array is such that adjacent lens surfaces are in contact with or connected to each other, and the exit-side lens array is provided. No means for optically separating each lens unit is provided on the exit side surface of the holder unit. That is, in this embodiment, the diameter of the exit-side lens surface of the lens unit of the exit-side lens array is increased, and adjacent lens surfaces are arranged close to each other or connected. Therefore, in this embodiment, it is possible to substantially eliminate the need to cover the exit surface of the holder portion of the lens array on the exit side with a light shielding material for preventing light leakage.

In another preferred embodiment, the exit lens surface of the lens unit of the exit lens array is such that adjacent lens surfaces are close to each other, and the exit lens surface of the holder unit of the lens array is close to the exit lens surface. A narrow groove with a bottom is formed in a region between the adjacent lens surfaces on the surface. The bottomed groove prevents crosstalk between the lens portions, but because of its narrow width, adjacent lens surfaces on the emission side of each lens portion are close to each other. And a light image can be efficiently emitted from the light source to form a bright image. In addition, this narrow bottomed groove allows light to be effectively emitted from an adjacent lens portion in a phase where light is finally emitted in a lens array assembly, or allows light to be emitted from between adjacent lens portions. Can be prevented.

In a preferred embodiment, each lens array is formed in a long block shape so that a plurality of lens portions are linearly arranged at predetermined intervals. The lens array assembly formed in this manner is suitable for forming an image of a reading line on an original mounting surface on a light receiving element at an equal magnification of an erect in an optical device that reads an image in a line. .

In a preferred embodiment, each lens array is further combined by fitting a convex portion provided on one side and a concave portion provided on the other side adjacent to each other in the laminating direction. In this case, the assembling process of combining the lens arrays in a stacked manner becomes extremely simple.

According to a second aspect of the present invention, there is provided an optical device. The optical device includes a document placing surface, a light receiving element, and the first aspect of the present invention disposed between the document placing surface and the light receiving element. And a lens array assembly according to any one of (1) to (3), wherein an erect equal-magnification image of the original placed on the original placing surface is formed on the light receiving element. By using the lens array assembly according to the first aspect of the present invention as the lens array of the optical device, the cost of the lens array is significantly reduced, which greatly contributes to the cost reduction of the device. Further, since the lens diameter of the lens array on the emission side is enlarged, it is possible to form a bright erect equal-magnification image without wasting light incident on the lens array. Further, since the conjugate length and the depth of focus of the lens array assembly can be freely set, the degree of freedom in designing the optical device can be increased.

Other features and advantages of the present invention will become more apparent from the detailed description given below with reference to the drawings.

[0023]

Preferred embodiments of the present invention will be specifically described below with reference to the drawings.

FIG. 1 is a central longitudinal sectional view of a first embodiment of a lens array assembly 1 according to the present invention, FIG. 2 is a partial plan view thereof, FIG. 3 is a sectional view taken along line III-III of FIG. 1, and FIG. FIG.
5 is a sectional view taken along the line IV-IV of FIG.

This lens array assembly 1 has a first
The lens array 10 and the second lens array 20 are combined in a stacked state. Each lens array 10,
Reference numeral 20 denotes a plurality of lens units 11 and 21 arranged at regular intervals at the same pitch in the longitudinal direction;
Holders 12 and 22 are provided to connect the two, and as a whole, it has a long block shape having a rectangular cross section with a horizontal width larger than the diameter of the lens unit. At both ends in the longitudinal direction of each of the lens arrays 10 and 20, connecting means 13 and 23 for holding both lens arrays in a stacked state are provided. And each lens array 10, 20
It is a molded article made of a transparent resin, and as its material, for example, PMMA (polymethyl methacrylate (methacrylic resin)) or PC (polycarbonate), which is excellent in transparency, mechanical strength, and heat resistance, is suitably adopted. .

The first lens array 10 is arranged on the light incident side, and the second lens array 20 is arranged on the light emitting side. The lens unit 11 of each lens array 10, 20
21 is an entrance surface 11a, 21a and an exit surface 11b, 2
1b both have the form of a convex lens having a convex curved surface, and the optical axes of the lens section 11 of the first lens array 10 and the lens section 21 of the second lens array 20 are aligned. In this embodiment, the entrance surface 11a and the exit surface 11 of the lens unit 11 in the first lens array 10 are used.
the distance L ₁ between b, the distance between the emission surface 21b and the incident surface 21a of the lens unit 21 in the second lens array 20 L ₂
Are approximately equidistant. In addition, the entrance surface and the exit surface of each lens unit are appropriately spherical, so as to minimize each aberration.
Alternatively, aspheric surfaces are combined.

The lens diameter of the lens unit 11 of the first lens array 10 (incident side) is compared with the lens diameter of the lens unit 21 of the second lens array 20 (outgoing side). The latter is set larger. More specifically, the lens unit 11 of the first lens array 10
The outgoing side lens surface 11 with respect to the incoming side lens surface 11a
b has a larger diameter, and the exit-side lens surface 21b has a larger diameter than the entrance-side lens surface 21a of the lens unit 21 of the second lens array 20, and
The above-mentioned lens surface 1 facing between each lens array 10 and 20
1b and the lens surface 21a have substantially the same diameter, so that the lens portion 2 of the second lens array 20 as a whole is larger than the diameter of the lens portion 11 of the first lens array 10.
The diameter of 1 is set larger. In this case, in this embodiment, the exit-side lens surface 21b of the lens portion 21 of the second lens array 20 is further brought close so that adjacent ones substantially contact each other.

In the embodiment shown in the drawings, each lens portion 11 is provided in a holder portion 12 of a first lens array 10.
In order to optically separate from each other, a bottomed groove 14 that is immersed from the surface on the incident side is formed in a region between the lens portions 11. As shown in FIG. 2, the bottomed groove 14 preferably extends in the width direction of the lens array with a dimension longer than the diameter of the lens portion 11, and can be formed by resin molding using a mold. The lens unit 11 has a minimum width.
Is formed as deep as possible without adversely affecting the shape. In this embodiment, the groove 1
The inner surface 14a and the bottom surface 14b of the light-receiving member 4 are covered with a black or similar dark-colored light-shielding material 15. For example, in addition to forming a coating film using a dark color paint, the grooves 14 are filled with a dark color member (not shown).

In addition, in this embodiment, the area surrounding the lens portion 11 on the emission side surface of the first lens array 10 is covered with a black or near dark type light shielding material 16. Also in this case, for example, a coating film using a dark color paint is formed.

In the second lens array 20, there is no particular means for optically separating each lens portion as formed in the first lens array 10.

In the present embodiment, the connecting means 13 and 23 are provided with a projection 23a on the incident surface side of the end of the second lens array 20 and a concave portion on the exit surface side of the end of the first lens array 10. 13a, the projections 23a and the recesses 13a are fitted to each other to connect the two lens arrays 10 and 20 in a stacked state.

Light enters from the entrance surface 11a (first surface) of each lens unit 11 of the first lens array 10 and exits from the exit surface 1a.
1b (second surface), and enters from an entrance surface 21a (third surface) of each lens unit 21 of the second lens array 20,
A path of exiting from the exit surface 21b (fourth surface) is taken, but as described above, the second surface 11b is more advanced than the first surface 11a.
Has a larger diameter, and the fourth surface 21b is larger than the third surface 21a.
Is increased in diameter. The second surface 11b and the third surface 21
“a” has substantially the same diameter. Therefore, in this embodiment, the diameter of the lens surface is increased from the light incident side to the light emitting side. The technical significance of this will be described later.

The second lens array 20 can be obtained only by performing resin molding. The first lens array 10 can be manufactured by forming the above-described coating films 15 and 16 after obtaining the outer shape by resin molding. The coating films 15 and 16 can be easily formed by, for example, a transfer method using a stamp, a method in which a mask is applied to each lens surface, immersed in paint, dried, and then the mask is removed. Then, the lens array assembly 1 is assembled by inserting the second lens array 2 into the concave portion 13 a provided at the end of the first lens array 10.
It can be performed by an extremely simple operation of merely fitting the projection 23a provided at the end of the zero.

Next, the operation of the lens array assembly 1 according to the above embodiment will be described with reference to FIG.

The lens array assembly 1 is an erect equal-magnification image (a ′) of an object (a → b → c) placed at the starting point S of light.
→ b ′ → c ′), the distance H ₁ from the starting point S to the first surface 11a and the distance H ₂ from the fourth surface 21b to the imaging point R are substantially equidistant. It is said. The first to the respective distances H _1, H _2, a distance obtained by adding a fourth surface distance H ₃ corresponds to a so-called conjugate length. The longer the conjugate length, the deeper the so-called depth of focus. In order to deepen the depth of focus, each input / output surface of the lens units 11 and 21, that is,
The curvatures of the first to fourth surfaces 11a, 11b, 21a, 21b may be reduced. When the depth of focus becomes deep, even if the object is displaced from the starting point S in the light traveling direction, the out-of-focus image of the erect equal-magnification image decreases. Further, since the angle (angle of view) of light incident on the first surface of a certain lens unit from the starting point S is reduced, the aberration of each lens unit is reduced accordingly, and the resolution is improved. In the lens array assembly 1 according to the present invention, the curvatures of the lens portions 11 and 21 of each of the lens arrays 10 and 20 are freely set only by changing the resin molding die, and the above-described conjugate length or depth of focus is desired. It can be set as follows.

As shown in FIG. 5, the lens portions 11 and 21 of the lens arrays 10 and 20 are arranged in series on each optical axis C. The light passes through the convex lens portion 11 of the first lens array 10 and then passes through the second lens array 20.
Pass through the convex lens part 21 of. That is, the light starting from the starting point S is the first to fourth surfaces 11a, 11b, 21a, 2
When passing through 1b, it reaches a focus point R under a predetermined refraction action. More specifically, a primary focus is formed near the second surface 11b and the third surface 21a by refraction on the first surface 11a, so that the second surface 11b and the third surface 21a are opposed convex curved surfaces. Therefore, the light exits from the second surface 11b and
Due to refraction at the time of incidence on 1a, the light bends so as to return toward the starting point when viewed from the optical axis direction. Then, the light from the primary focal point forms a secondary focal point at the image forming point R on the exit side by refraction on the fourth surface 21b. By the plurality of convex lens portions 11 and 21 having the optical axis C aligned in this manner, a phenomenon equivalent to the meandering phenomenon of light observed in the SELFOC lens is obtained, and an object (a predetermined distance on the incident side of the lens array assembly 1) is obtained. An erect equal-size image (a ′ → b ′ → c ′) of a → b → c) is formed at a position at a predetermined distance on the emission side.

In the lens array assembly 1, a groove 14 is formed in the first lens array 10 on the emission side as a means for preventing crosstalk between adjacent lens portions, and is formed on an inner surface of the groove 14. Dark color coating 1
5 and a dark-colored coating film 16 formed in a region surrounding the lens unit 11 on the emission side. Therefore, light can be prevented from entering the first lens array 10 from a region other than the lens portion 11 to some extent by the groove 14, and light entering one lens portion 11 can be mixed into the adjacent lens portion. 14 or a coating 15 deposited on its inner surface. Further, the lens unit 1
The light leaks out of the area other than the emission surface 11b of
It is prevented by the coating film 16 on the emission surface side. This allows
Light crosstalk between the lens units 11 is effectively prevented. In this embodiment, the second lens array 20
Since the third surface 21a and the fourth surface 21b of the lens portion 21 have a larger diameter and the fourth surface 21b has a larger diameter than the third surface 21a, light incident from the third surface 21a is wasted. The light can be emitted from the fourth surface 21b without any change. And
In the embodiment shown in the figures, the fourth surfaces 21b are so close that the adjacent ones are in contact with each other, so that light leaks out from the region between the adjacent fourth surfaces 21b, which deteriorates the image quality. Is virtually eliminated. Therefore, the second lens array 20 does not need to be provided with a means for preventing crosstalk, such as a dark-colored coating film or a groove, at least on the exit surface side. In this case, the amount of light emitted from each lens unit 21 of the second lens array 20 is increased, which greatly contributes to obtaining an efficient image. Therefore, the lens array assembly 1 according to this embodiment can appropriately prevent image deterioration due to crosstalk while securing the brightness of the erect equal-size image obtained thereby.

FIG. 6 shows a second embodiment of the lens array assembly 1 according to the first aspect of the present invention. In the first lens array 10 according to this embodiment, a groove 14 for preventing crosstalk between the lens units 11 is formed in a bottomed shape recessed from the emission side. On the inner surface 14a of the groove 14, a dark-colored coating film 15 is formed.
Is formed, and a dark-colored coating film 17 is also formed in a region surrounding the lens surface 11a (first surface) on the incident side of the first lens array 10. In this embodiment, the entrance surface 11a (first surface) and the exit surface 11b (second surface) of each lens unit 11 of the first lens array 10 have substantially the same diameter. On the other hand, in the second lens array 20, as in the first embodiment, the exit surface 21b (fourth surface) of each lens unit 21 has a larger diameter than the entrance surface 21a (third surface). However, the adjacent exit surfaces 21b are not in contact with each other as in the first embodiment, but are provided with a small interval, and a narrow bottomed groove 18 is provided in this interval.
Are formed. The narrow bottomed groove 18 has a width of, for example, 0.2 mm or less, and is difficult to mold with a mold. For example, an excimer laser or a pulsed CO ₂ laser is irradiated through a predetermined mask. It can be formed by the following. A coating film is preferably formed in the narrow groove 18, but the coating film may not be formed. Other configurations are the same as those of the first embodiment.

As shown in FIG. 7, in this embodiment, as in the first embodiment, the object (a
→ b → c), an erect equal-magnification image (a ′ → b ′ → c ′) is formed at the image forming position R. In this embodiment, in the first lens array 10, the light is
The coating film 17 on the incident surface side prevents entry into the lens array 10 from a region other than 1a. Further, the light incident on a certain lens portion 11 is prevented from being mixed into an adjacent lens portion by the groove 14 or the coating film 15 attached to the inner surface thereof. Further, the leakage of light from a region other than the emission surface 11b of the lens portion 11 is prevented by the groove 14 immersed from the emission surface side or the coating film 15 attached to the inner surface thereof. Thereby, crosstalk of light between the lens units is effectively prevented.

In the second lens array 20,
A bottomed groove 18 is formed between each emission surface 21b of each lens portion 21 to prevent crosstalk between the lens portions 21. Since the groove 18 has a small width, it is adjacent to the emission side of each lens portion. The light-emitting surfaces 21b are close to each other, so that light can be efficiently emitted from the emission surface 21b to form a bright image. In addition, the narrow bottomed groove 18 can be used to effectively emit light from the adjacent lens portion in the phase where light is finally emitted in the lens array assembly, or to emit light from between adjacent lens portions. It can be prevented from being caused. In addition, since the lens diameter is increased from the first surface 11a to the fourth surface 21b, the second lens array 20
An erect equal-magnification image (a ′ → b ′ → c ′) with sufficient brightness can be obtained without wasting light that has been appropriately incident on the image.

FIG. 8 shows a contact type image sensor 30 as an optical device according to the second aspect of the present invention.
The image sensor 30 includes a case 31 having a substantially rectangular cross section and having an internal space penetrating in the up-down direction.
However, a substrate 35 is mounted on the lower surface opening 34. An image sensor chip 36 as a light receiving element and an LED 37 as a light emitting element are mounted at appropriate places on the upper surface of the substrate 35. The image sensor chips 36 have a large number of light receiving portions arranged in a line in a direction perpendicular to the paper surface. An appropriate number of the light receiving portions are closely arranged in the longitudinal direction according to the reading width.

An optical axis C extending vertically through the image sensor chip 36 and reaching the transparent cover 33 is set. The lens array assembly 1 according to the first aspect of the present invention is provided at an intermediate portion of the optical axis C. It is arranged while being held by a holder 38 formed in the case 31. This holder 38
Is formed by the inner surface of the side wall of the case 31 and the intermediate wall 39 formed so as to block the image sensor chip 36 and the LED 37 on the substrate 35. In this case, a line that intersects with the optical axis C on the surface of the transparent cover 33 is a reading line La. The distance Ha on the optical axis C from the reading line La to the image sensor chip 36 is a so-called conjugate length. The upper end of the intermediate wall 39 is interrupted on the way, and therefore,
The space in which the LEDs 37 are arranged is connected to the upper space of the lens array assembly 1 including the optical axis C at the upper part. Further, in the embodiment, the space 40 in which the LED 37 is mounted is gradually narrowed while bending toward the reading line La by bending the inner surface 31a of the case and the one side surface 39a of the intermediate wall 39. The wall 31a forming the space 40 is colored white, for example, and has a high reflectance.

The original D is sent in a predetermined direction while being backed up by the platen P so that the original D comes into contact with the reading line La on the surface of the transparent cover 33.

In the above configuration, the light emitted from the LED is guided to the vicinity of the reading line La, and illuminates the document D. An image of the original along the reading line La is formed as an image of the same size on the image sensor chip 36 by the lens array assembly 1, and the image sensor chip 36 outputs image information as a signal of a light receiving unit arranged in the line direction. Read. Each time the document D is sent in the sub-scanning direction, the image information on the above-described reading line La is read, and the image information is combined to form image information.

In the lens array assembly 1 according to the first aspect of the present invention, since the depth of focus and the conjugate length can be set as desired, the degree of freedom in the configuration of the image sensor 30 is increased. When the depth of focus is deep, even a cool original D slightly floating with respect to the transparent cover 33 can be properly read with a reduced degree of out-of-focus, so that such an image sensor 30 can be configured as a handy scanner. It becomes convenient.

Of course, the scope of the present invention is not limited to the above embodiments. In the embodiment, the lens array assembly is configured by laminating two lens arrays. However, it is also possible to configure the lens array assembly by laminating three or more lens assemblies.

In the embodiment, as means for optically separating the lens portions, a groove 14 is formed in the holder portion 112, the inner surface of the groove 14 is covered with a dark-colored light-shielding material 15, and the groove 14 is formed. Areas other than the lens section 11 in the holder section 12 on the side where no is formed are dark-colored light shielding members 16 and 17.
However, it is also within the scope of the present invention to cover a region other than the lens portion of the holder portion with a dark light shielding material without providing a groove.

Further, in the lens array of the embodiment, the lens units are arranged in one line at equal intervals. However, a plurality of lens units may be arranged in two or more lines.
It is of course included in the scope of the present invention to arrange the lens portions of the lens array that are stacked on each other, for example, in a lattice shape or a honeycomb shape so as to form a real-sized image with a planar image.

[Brief description of the drawings]

FIG. 1 is a central longitudinal sectional view showing a first embodiment of a lens array assembly according to a first aspect of the present invention.

FIG. 2 is a partial plan view of the lens array assembly.

FIG. 3 is a sectional view taken along line III-III of FIG. 1;

FIG. 4 is a sectional view taken along line IV-IV of FIG. 1;

FIG. 5 is an operation explanatory view.

FIG. 6 is a central longitudinal sectional view showing a second embodiment of the lens array assembly according to the first aspect of the present invention.

FIG. 7 is an operation explanatory view.

FIG. 8 is a cross-sectional view illustrating a contact image sensor according to an embodiment of the optical device according to the second aspect of the present invention.

FIG. 9 is a perspective view showing an example of a conventional lens array.

FIG. 10 is a sectional view of a main part of the lens array shown in FIG. 9;

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 lens array assembly 10 first lens array 11 lens portion 11a (of lens portion) incidence surface (first surface) 11b (of lens portion) emission surface (second surface) 12 holder portion 13 connecting means 14 groove 15 light shielding material Reference Signs List 16 light shielding material 17 light shielding material 18 groove 20 second lens array 21 lens portion 21a (of lens portion) incident surface (third surface) 21b (of lens portion) emission surface (fourth surface) 22 holder portion 23 connecting means 30 Contact type image sensor 31 Case 33 Transparent cover 35 Substrate 36 Image sensor chip 37 LED

Claims (12)

[Claims] 1. A lens array comprising a plurality of lens units arranged in parallel and a holder unit for integrally connecting the lens units, the plurality of lens arrays being formed by resin integral molding. A lens array assembly that is laminated so that the optical axes of the lens portions are aligned and combined so as to obtain an erecting equal-magnification image, wherein the lens diameter of the lens portion of the lens array on the exit side is the incident side. A lens array assembly, wherein the lens diameter is set to be larger than the lens diameter of the lens portion of the lens array. 2. The lens array assembly according to claim 1, wherein at least the first lens array on the incident side of the plurality of lens arrays is provided with a unit for optically separating the lens units. 3. The lens array assembly according to claim 2, wherein the means for optically separating the lens portions includes a groove provided between each adjacent lens portion in the holder portion. 4. The lens array assembly according to claim 3, wherein said groove is formed in a bottomed shape so as to enter a predetermined depth from an incident side or an emission side. 5. The lens array assembly according to claim 3, wherein an inner surface of the groove is covered with a black or near-dark light shielding material. 6. The means for optically separating the lens portions from each other may further include a black or near-dark light-blocking material covering a region surrounding the lens portion on the incident side surface and / or the outgoing side surface of the holder portion. The lens array assembly according to claim 3, comprising: 7. An outgoing lens surface of a lens portion of an outgoing lens array of a plurality of lens arrays, wherein adjacent lens surfaces are extremely close to, in contact with, or connected to each other. Item 3. A lens array assembly according to item 2. 8. The exit-side lens surface of the lens unit of the exit-side lens array is in contact with or connected to adjacent lens surfaces, and the exit-side lens array of the exit-side lens array has a lens unit. The lens array assembly according to claim 7, wherein the side surface is not provided with a unit for optically separating each lens unit. 9. The exit-side lens surface of the lens portion of the exit-side lens array has adjacent lens surfaces close to each other, and an adjacent lens surface of the exit-side surface of the holder portion of the lens array. The lens array assembly according to claim 7, wherein a narrow bottomed groove is formed in a region between the lens arrays. 10. The lens array assembly according to claim 1, wherein each lens array is formed in a long block shape such that a plurality of lens portions are linearly arranged at predetermined intervals. 11. The lens array assembly according to claim 10, wherein each lens array is combined by fitting a convex portion provided on one side and a concave portion provided on the other side adjacent to each other in the stacking direction. . 12. A document placed on a document placing surface, comprising a document placing surface, a light receiving element, and the lens array assembly according to claim 1 disposed therebetween. An optical device characterized in that an erecting equal-magnification image is formed on a light receiving element.