JP2004007820A - Rod lens array, and apparatus and system for reading image - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To allow illumination light to reach a reading position on the surface of an original even in an ultra-slim CS using a rod lens array of small TC. <P>SOLUTION: A contact image sensor is constituted by using image forming elements having sideboards of an image forming lens of different thicknesses, wherein the thickness of the sideboard on the side of a light source is smaller while the sideboard on the opposite side concerning the image forming lens is greater. A light path from the light source to the surface of the original is secured by reducing the thickness of the sideboard on the side of the light source, and the image forming element is reliably positioned optically and supported securely by increasing the thickness of the sideboard on the opposite side. <P>COPYRIGHT: (C)2004,JPO

Description

The present invention relates to a rod lens array, an image reading device and an image reading system using the same.

In recent years, due to the rapid spread of personal computers, the use of reading images such as photographs and illustrations by an image input information processing device called a scanner, processing the data on a computer, and outputting it to a postcard, a document, or the like has been widespread even in ordinary households. ing. When such a scanner is used in ordinary households, it is desired that the scanner be smaller and lighter in terms of installation area, simplicity of handling, and design as part of an interior.

(4) In order to realize a reduction in size and weight, there is a type in which a contact type image sensor that reads an image on a document in close contact with a document is used in a reading unit of a scanner. FIG. 15 is a schematic perspective view showing the appearance of a conventional contact image sensor. Reference numeral 1 denotes a frame that supports the entire image sensor, and reference numeral 5 denotes a cover glass that comes into contact with a document and defines a reading surface thereof. The frame 1 has a built-in sensor array in which a large number of optical sensors are arranged along the longitudinal direction (the direction of arrow DM). Here, the DM direction is defined as the main scanning direction, and the short direction of the frame 1 ( An arrow DS direction perpendicular to the DM direction) is defined as a sub-scanning direction.

FIG. 16 is a diagram showing a cross section taken along line BB ′ in FIG. A rod lens array 7 as an imaging element is arranged in a first space 1A of the frame 1, and an illumination device 6 is arranged in a second space 1B. The first space 1A and the second space 1B communicate with each other. The illuminating device 6 guides light from one or more LED light sources 63 in the main scanning direction (DM direction) and also prevents light leaking from the light guide plate 61 having a function of illuminating the document PP. A light guide plate 61 is provided, and the housing 62 is a frame member having a function of efficiently illuminating the document PP. The light emitted from the light source 6 irradiates the original PP on the cover glass 5, and the reflected light forms an image on the sensor IC 3 provided on the sensor substrate 4 by the rod lens array 7. In addition, the sensor substrate 4 is disposed in the third space 1C.

When assembling such an image sensor, first, the lighting device 6 is fixed to the mounting surface 1D of the frame 1 with an adhesive or a screw, the rod lens array 7 is inserted into the first space 1A, and the frame 1 is fixed with the adhesive or the screw. Fix to mounting surface 1E. Then, the sensor substrate 4 provided with the sensor IC 3 is fixed to the frame 1 by the frame 2 to complete the image sensor.

As shown in FIG. 17, the rod lens array 7 has a plurality of rod lenses 71 arranged in a line of one or more rows, sandwiched from both sides by thin plate-like frame members 72, 73 called side plates, and filled with resin in the gap. It is formed by filling and fixing.

This rod lens 71 is a cylindrical lens element having a lens function by gradually changing the refractive index from the center to the periphery. The diameter of this lens element is about 0.6 mm, and the thickness of the side plate is about 0.5 mm. Such a rod lens array has a function of forming an image on the object plane through the lens array on the opposite image plane at the same magnification, erecting an original on the object plane, and placing the sensor on the image plane. It is suitable for reading an image by arranging a light receiving surface to form an image on a document surface on a sensor surface.

FIG. 18 is a diagram showing the relationship between the rod lens array 7 and the object plane and image plane. The distance between the object plane o and the image plane i is determined by the characteristics of each single lens used, and is called a conjugate length (TC). The distance from the lens end surface to the object plane or the image plane is called a working distance (L0). Further, what is indicated by Z0 in the drawing is the length of each single lens constituting the lens array, that is, the height of the lens array.

At present, there are two types of lens arrays mainly used in this type of image sensor, a type having a TC of about 9 mm and a type of a lens having a TC of about 18 mm. The latter type is used when emphasis is placed on the focal depth. Here, the case where the TC is 9.1 mm will be described as an example.

FIG. 19 shows an example of an image sensor using a rod lens array having a TC of 9.1 mm. FIG. 20 shows the positional relationship between the rod lens array 7, the lighting device 6, the cover glass 5, and the sensor substrate 4. FIG. Here, as the lighting device 6, a device in which a plurality of LED chips are arranged in a line on a substrate is used. The height Z0 of the rod lens array 7 is 4.3 mm, and the distance from the lens array end surface to the surface of the sensor IC is 2.4 mm, corresponding to the working distance L0 described above. Further, the distance L0 ′ from the lens array end surface to the document surface is slightly larger than the working distance L0 due to the presence of a cover glass having a thickness d of 1 mm and a refractive index of about 1.5, 2.7 mm. Is set to Therefore, the distance from the document surface to the surface of the sensor IC is 9.4 mm, which is slightly larger than the TC of the lens array, and the thickness of the image sensor is about 11 mm including the thickness of the sensor substrate.

実 現 It has been proposed to employ an imaging element having a short optical length TC in order to realize a compact product configuration, which is the greatest advantage of such a contact image sensor, and to meet the demand for further miniaturization.

It is known that the TC of the lens array is given by the following equation.

　上記式において、Ａは各単レンズの屈折率分布定数、ｎ０は各単レンズの光軸上屈折率、Ｚ０は各単レンズの長さ、Ｐは１周期長、Ｌ０は作動距離を表わしている。

In the above formula, A is the refractive index distribution constant of each single lens, n0 is the refractive index on the optical axis of each single lens, Z0 is the length of each single lens, P is one cycle length, and L0 is the working distance. .

方法 As a method for shortening the TC represented by the above equation, there is a method of slightly increasing the length of each single lens constituting the lens array, that is, the height Z0 of the lens array. For example, in the lens array of TC = 9.1 mm shown in FIG.

となっているが、これらの定数のうちｎ０と

, But among these constants, n0 and

をそのままで、Ｚ０をやや大きくして、例えばＺ０＝４．５ｍｍとすれば、前述の式を用いてＴＣ＝８．１ｍｍとなることがわかる。図２１は、このＺ０＝４．５ｍｍ、ＴＣ＝８．１ｍｍとしたレンズアレイを示したものであり、このようにすると、各単レンズ内部の屈折率分布を変えずにＴＣを短くすることができる。しかしながらこの方法では、各単レンズの長さ、すなわちレンズアレイ自体の高さＺ０はかえって大きくなるため、ＴＣの短縮には限界があり、十分に短いＴＣを実現することは困難である。

If Z0 is slightly increased, for example, if Z0 = 4.5 mm, TC = 8.1 mm is obtained using the above equation. FIG. 21 shows a lens array in which Z0 = 4.5 mm and TC = 8.1 mm. In this case, TC can be shortened without changing the refractive index distribution inside each single lens. it can. However, in this method, since the length of each single lens, that is, the height Z0 of the lens array itself, is rather large, there is a limit in shortening TC, and it is difficult to realize a sufficiently short TC.

Therefore, as another method of shortening the TC, there is a method of changing the refractive index distribution inside each single lens so that the refractive index changes more rapidly from the central portion to the peripheral portion. That is, among the above constants,

を変更することにあたる。図２２は、このようなレンズアレイを示したものであり、各単レンズに入射した光束がレンズ内部でより大きく曲げられるため、結果的にＴＣをより短くすることが可能である。このような方法によれば、ＴＣを短くしながら、同時にＺ０も小さくすることができる。図２２のレンズアレイは、ＴＣが４．７ｍｍ、レンズアレイ自体の高さＺ０は２．２ｍｍ、レンズアレイとセンサＩＣの表面までの距離Ｌ０は１．３ｍｍである。レンズアレイと原稿面までの距離Ｌ０’は、その間に厚さ１ｍｍ、屈折率約１．５のカバーガラスが存在しているためにやや大きくなり、１．６ｍｍとなっている。

To change. FIG. 22 shows such a lens array. Since a light beam incident on each single lens is bent more inside the lens, the TC can be shortened as a result. According to such a method, Z0 can be reduced while TC is shortened. The lens array in FIG. 22 has a TC of 4.7 mm, a height Z0 of the lens array itself of 2.2 mm, and a distance L0 between the lens array and the surface of the sensor IC of 1.3 mm. The distance L0 ′ between the lens array and the document surface is slightly increased to 1.6 mm due to the presence of a cover glass having a thickness of 1 mm and a refractive index of about 1.5 therebetween.

FIG. 23 shows an image sensor using such a rod lens having a short TC. 23, the glass 5 is fixed to the frame 1 while the illumination device 6 inserted into the second space 1B and the rod lens array 7 inserted into the first space 1A are pressed against the frame 1 by the cover glass 5. , The light source 6 and the rod lens array 7 are simultaneously fixed. The sensor substrate 4 on which the sensor IC 3 is provided is fixed to the frame 1 with an adhesive or a screw or by caulking the frame 1 itself. With this configuration, the size of the image sensor can be further reduced in the thickness direction.

FIG. 24 shows the relationship between the rod lens array 7 having a TC of 9.1 mm and the illumination light illuminated from the illumination device 6. The light beam emitted from the illuminating device 6 obliquely passes from the end surface of the lens array 7 to the document surface (L0 '= 2.7 mm), and forms the image position of the lens array on the document surface, that is, the read position. Illuminate P. Actually, in consideration of the mechanical tolerance of the image sensor assembly, it is designed to illuminate an area of ± 0.2 mm or more around the read position P with respect to the read position P, and with respect to the optical axis of the lens array 7, The angle θ at which the document surface is illuminated from the illuminating device 6 is usually such that the main luminous flux is distributed between 30 ° and 50 °.

FIG. 25 is a view showing the relationship between the lens array 7 and the illumination light in the image sensor using the 4.7 mm rod lens array 7 whose TC is about half that shown in FIG. The light beam emitted from the illuminating device 6 illuminates the original surface by obliquely passing from the end surface of the lens array 7 to the original surface (L0 ′ = 1.6 mm), and illuminates the original surface. Since the length L0 from the end face to the image forming position is also short, it is necessary to arrange the illumination device 6 as close to the lens array 7 as possible. However, due to the thickness of the frame material, there is a problem that the read position P cannot be illuminated even if the illumination device 6 is brought as close as possible to the lens array 7. When an image sensor is configured using a lens array having a short TC as described above, there is a problem that an image on a document surface cannot be effectively read because illumination light does not sufficiently reach a reading position.

When the rod lens array 7 is arranged at a position away from the cover glass 5, the sensor receives the direct light or the indirect light of the internally reflected light emitted from the light source 6 and the stray light from the outside of the contact type image sensor. It is necessary to provide a light-shielding means for preventing such a problem. However, when an imaging element having a short TC is used, there is a problem that it becomes more difficult to irradiate an image forming position with a light source due to the installation of the light-shielding means. there were.

The present invention has been made to solve the above-mentioned problem, and a rod lens array according to claim 1 is an illumination device for irradiating a document in a line, and an image signal which reflects reflected light from the document. Used in an image reading apparatus having a linear image sensor that converts and outputs the reflected light, a rod lens array for imaging the reflected light on the linear image sensor, a plurality of rod lenses, the plurality of A first and a second side plate for positioning by arranging and holding rod lenses from both sides are provided, and the thickness of the first and second side plates is made different. .

The rod lens array according to claim 5, which is used for an image reading device including an illumination device for irradiating a document in a line and a linear image sensor for converting reflected light from the document into an image signal and outputting the image signal. A rod lens array for imaging the reflected light on the linear image sensor, comprising: a plurality of rod lenses; and a side plate for arranging and positioning the plurality of rod lenses. The side plate is fixed to only one side of the arrangement of the rod lenses.

The rod lens array according to claim 8, which is used for an image reading apparatus including an illuminating device for irradiating a document in a line and a linear image sensor for converting reflected light from the document into an image signal and outputting the image signal. A rod lens array for imaging the reflected light on the linear image sensor, the rod lens array comprising: a plurality of rod lenses; and a side plate for arranging and positioning the plurality of rod lenses. When the diameter of the lens is φ [mm] and the thickness of the side plate is t [mm], the diameter of the rod lens array and the thickness of the side plate are set so that φ / 2 + t ≦ 0.5 [mm]. Is defined.

The image reading device according to claim 10, wherein the illuminating device irradiates the original in a line, a linear image sensor that converts reflected light from the original into an image signal and outputs the image signal, and outputs the reflected light to the linear image sensor. And a rod lens array configured by arranging a plurality of rod lenses for forming an image on the image sensor and sandwiching the first and second side plates having different thicknesses from both sides from both sides. .

15. The image reading device according to claim 14, wherein the illumination device irradiates the original in a line, a linear image sensor that converts reflected light from the original into an image signal and outputs the image signal, and reflected light from the subject. And a rod lens array configured by arranging a plurality of rod lenses for forming an image on the linear image sensor and fixing a side plate on only one side.

18. The image reading apparatus according to claim 17, wherein a transparent member on which the document is placed, an illuminating device for irradiating the document in a line, and light reflected from the document converted into an image signal and output. A linear image sensor, and a rod lens array configured by arranging a plurality of rod lenses for imaging the reflected light on the linear image sensor and positioning the rod lenses by a side plate, wherein the reflected light is The shortest distance between the surface incident on the lens array and the document surface is L0 [mm], the diameter of the rod lens is φ [mm], the thickness of the side plate is t [mm], the refractive index of the transparent member is n, and the transparent member is n. Assuming that the thickness is d [mm], φ / 2 + t ≦ d × tan (arcsin ((sin30 °) / n)) + (L0−d) × tan30 ° −0.2 [mm] That each member is specified And butterflies.

21. The image reading system according to claim 20, wherein the illumination device irradiates the original in a line, a linear image sensor that converts reflected light from the original into an image signal and outputs the image signal, and outputs the reflected light to the linear image sensor. A reading unit having a rod lens array configured by arranging a plurality of rod lenses for forming an image on the image sensor and sandwiching the first and second side plates having different thicknesses from both sides from both sides; Signal processing means for performing predetermined processing on the image signal output from the image sensor.

26. The image reading system according to claim 25, wherein the illuminating device irradiates the original in a line, a linear image sensor that converts reflected light from the original into an image signal and outputs the image signal, and reflected light from the subject. A reading unit having a rod lens array formed by arranging a plurality of rod lenses for forming an image on the linear image sensor and fixing a side plate to only one side, and an image output from the image sensor. Signal processing means for performing predetermined processing on the signal.

As described above, according to the present invention, a thin and small rod lens array can be obtained. Further, according to the present invention, it is possible to obtain a compact and high-quality image reading device and an image reading system by using a thin and small rod lens array while securing an optical path of light from an illumination device for illuminating a document. Can be.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First form)
FIG. 1 is a perspective view of a contact type image sensor which is a reading unit embodying the present invention, and FIG. 2 is a cross-sectional view taken along line AA ′ of FIG. The same components as those described with reference to FIGS. 15 and 16 are denoted by the same reference numerals, and description thereof is omitted.

In FIG. 1, reference numeral 1 denotes a frame serving as a support, and reference numeral 5 denotes a cover glass as a transparent member which comes into contact with a document and defines a reading surface thereof. In FIG. 2, reference numeral 6 denotes an illuminating device for illuminating the document PP. The illuminating device 6 has a function of guiding light 64 from one or more LED light sources in the main scanning direction DM and illuminating the document PP in a line shape. The light guide plate 61 includes a housing 62 having a function of preventing light leaking from the light guide plate 61 and illuminating the document PP efficiently by determining the position of the light guide plate 61.

Reference numeral 7 denotes a rod lens array that forms an image of light from the document PP illuminated by the illumination device 6, and includes rod lenses 71 and side plates 72 and 73 for forming the rod lenses 71 in one or more rows of lens arrays. ing. Here, the rod lens 71 and the side plates 72 and 73 are fixed with an adhesive such as a resin. The light from the document PP imaged by the rod lens 71 is photoelectrically converted into an image signal by the sensor IC 3, and the sensor IC 3 is read and a plurality of sensors, such as glass epoxy materials, are formed in a line corresponding to the length of the document. The linear image sensor 10 is configured by accurately arranging them on the substrate 4. Further, the sensor substrate 4 is electrically connected to the image reading device.

In the image sensor according to the present embodiment, the thickness of the first side plate 72 disposed on the side of the illumination device 6 constituting the rod lens array 7 is the same as that of the first side plate 72 disposed on the side opposite to the side plate 72 with the rod lens 71 interposed therebetween. The side plate 73 is thinner than the second side plate 73, and the illuminating device 6 and the rod lens 71 are moved to a position where the light 64 from the illuminating device 6 can sufficiently illuminate the image forming position of the rod lens 71, that is, the position where the read position P of the document PP is sufficiently illuminated. Can be in close proximity. However, when the thickness of the side plate is reduced in this way, the rigidity of the rod lens array 7 itself is reduced, and it may be difficult to accurately perform optical positioning when supported by the frame. . In this case, by increasing the thickness of the side plate 73, the thickness of the side plate 72 on the lighting device side can be reduced without reducing the rigidity of the rod lens array itself.

With this configuration, even when the side plate 72 of the rod lens array 7 is brought into surface contact with the frame 1 and the rod lens array 7 is pressed against the frame 1 with the cover glass 5 to fix the cover glass 5 to the frame 1, Since the rod lens array 7 of the present embodiment has sufficient rigidity, the lens array 7 can be optically positioned and fixed easily and reliably. Further, by bringing the lens array 7 into close contact with the frame 1, it is possible to block direct light from the lighting device 6, indirect light of internally reflected light, and light reception to the sensor IC 3 due to stray light from the outside.

(Second form)
FIG. 3 is a cross-sectional view of the contact type image sensor according to the second embodiment. In the present embodiment, the side plate on the lighting device 6 side constituting the rod lens array 7 is eliminated, and the rod lens 71 is held only by the side plate 73. The side plate 73 and the rod lens 71 are fixed with an adhesive such as a resin. With this configuration, the optical path from the illumination device 6 that illuminates the document PP can be maximized.

Further, on the lighting device 6 side, a surface that appears when the frame material of the rod lens array 7 is eliminated, for example, the surface of the rod lens 71 or a painted surface, or a resin surface of an adhesive for forming the lens array and the lighting device 6, the surface of the housing 62 is in close contact with the surface, and it is possible to block direct light from the lighting device 6, indirect light of internal reflected light, or stray light from the outside from entering the sensor IC3. .

(Third form)
FIG. 4 is a sectional view of a contact type image sensor according to a third embodiment, and FIG. 5 is a top view thereof.

As shown in FIGS. 4 and 5, the image sensor according to the present embodiment reads a plurality of sensor ICs 3 each having a linear photoelectric conversion element group corresponding to the length of a document to be read and a sensor substrate such as a glass epoxy material in a line. 4, a linear image sensor 10, a rod lens array 7, an illuminating device 11, a cover glass 5 made of a light transmitting member for supporting a document, and a metal such as aluminum for positioning and holding them. And a frame 1 made of a resin material such as polycarbonate.

In this configuration, the document held by the cover glass 5 pressed by a roller or the like (not shown) is illuminated by the illumination device 11 by sequentially switching the three colors of R, G, and B lights from an oblique direction. Then, optical information of R, G, and B colors from the original is imaged on the sensor IC 3 by the rod lens array 7, and the sensor IC 3 converts the optical information of R, G, and B colors into electrical signals. The converted image signal is transmitted to the system as described later, where the R, G and B electrical signals are processed to reproduce a color image.

Next, FIG. 6 shows a cross-sectional view of the lighting device, and FIG. 7 shows a side view thereof. The illuminating device 11 is an R, G, B three-color LED in which three color LED elements of a red (R) LED element 311, a green (G) LED element 312, and a blue (B) LED element 313 are packaged as one light source. It comprises a light source 31 and a light guide 32 made of a member having excellent light transmittance such as an acrylic resin. The peak emission wavelengths of the R, G, and B LEDs are selected from 600 to 660 (nm), 510 to 550 (nm), and 430 to 480 (nm) for the purpose of improving color reproducibility.

The LEDs 31 are arranged such that light enters the light guide from one or both ends of the light guide 32 in the longitudinal direction. As shown in FIG. The total reflection is repeated at the interface and propagates through the light guide 32.

Further, as shown in FIG. 7, the light guide 32 has a fine sawtooth shape formed continuously in the longitudinal direction of the light guide 32, and the sawtooth portion is formed in the light propagating through the light guide. Only the light incident on the light guide 321 is different from the reflection on the other surface, and largely changes its direction toward the document surface, and the interface between the next light guide 32 and air no longer satisfies the total reflection angle condition. The light is emitted in the direction. The sawtooth portion 321 may be a reflection surface on which aluminum vapor deposition, silver, white ink, or the like is printed, or a shape using a sawtooth shape and utilizing complete reflection at an interface with air. Alternatively, the same effect can be obtained by simply printing or roughening white ink or the like without forming a sawtooth shape.

Furthermore, in order to make the illuminance on the original surface uniform, the width of the sawtooth is increased as the distance from the light source increases, or simply in the case of white ink printing, the printing area is gradually increased to achieve more uniform illumination of the original surface. It is possible to do. The illuminance of the document surface can be increased by covering the portion of the light guide 32 other than the light emitting portion to the document with a member such as white having high light reflection efficiency.

Next, FIG. 8 shows a cross-sectional view of the rod lens array 7 used in the present embodiment, and its characteristics will be described. In the rod lens array shown in FIG. 8, the refractive index distribution inside each single lens is changed from the conventional one, and the refractive index difference between the peripheral portion and the central portion is made larger. For this reason, the light beam incident on each single lens is more greatly bent inside the lens, and as a result, the TC is about half that of the conventional rod lens array.

{Specifically, the imaging conjugate length TC is 4.7 mm, the height Z0 of the lens array itself is 2.2 mm, and the distance L0 between the lens array and the surface of the sensor IC is 1.3 mm. The distance L0 'between the lens array and the document surface is slightly increased to 1.6 mm due to the presence of a cover glass having a thickness of 1 mm and a refractive index of about 1.5 therebetween.

Further, in the lens array of the present embodiment, the diameter φ of each rod lens 71 constituting the lens array is reduced from 0.3 mm in the related art to 0.3 mm. In addition, the thickness t of the side plates 72 and 73 that sandwich the rod lenses arranged in an array from both sides is reduced from the conventional 0.5 mm to 0.3 mm. Therefore, the distance from the optical axis of the lens array to the outside of the side plate is 0.45 mm, which is significantly reduced as compared with the conventional one.

However, when the diameter of the rod lens is reduced and the thickness of the side plate is further reduced as described above, the rigidity of the rod lens array 7 itself is reduced, so that accurate optical positioning when supported by the frame is required. May be difficult. In this case, as described in the first embodiment, only the thickness of the side plate 72 on the side where the illuminating device 6 is arranged is set to 0.3 mm, and the thickness of the opposite side plate 73 is set to the conventional value of 0 mm. What is necessary is just to make it thicker than 0.5 mm. In this way, the thickness of the side plate on the lighting device side can be reduced without reducing the rigidity of the rod lens array itself.

FIG. 9 shows the relationship between the lens array and the illumination light from the illumination device according to the present embodiment, and FIG. 10 shows an enlarged view thereof. Generally, the main light flux is generally distributed between 30 ° and 50 ° at the angle θ at which the illumination light emitted from the illumination device irradiates the document surface. Now, this angle θ is set to 30 °, and in consideration of the mechanical tolerance of the image sensor assembly, it is necessary for this illumination light to be able to illuminate an area of ± 0.2 mm or more around the reading position P on the left and right sides. The conditions will be considered with reference to FIG.

Now, the approach distance s when the illuminating light emitted from the illuminating device indicated by Ray in the drawing reaches the cover glass, is refracted there, and reaches the document surface is the distance that the light beam travels before reaching the cover glass. This is the sum of s1 and the distance s2 that travels inside the cover glass. The distance s1 that the light beam travels to reach the cover glass is a value obtained by multiplying (L0′-d), which is the distance from the end of the lens array to the cover glass, by the tangent of θ, which is the angle of the light beam. (D: thickness of cover glass) Here, if θ is 30 °, this is: s1 = (L0′−d) × tan30 °
It becomes. When the light beam enters the inside of the cover glass, its angle is bent by refraction and becomes θ ′. Θ ′ is given by the formula of refraction θ ′ = arcsin ((sin30 °) / n)
Given by Here, n is the refractive index of the cover glass. The distance s2 that the light beam travels inside the cover glass is a value obtained by multiplying the thickness d of the cover glass by the tangent of θ ′, which is the angle of the light beam inside the cover glass. Since θ ′ is given by the above equation, this is given by s2 = d × tan (arcsin ((sin30 °) / n))
It becomes. On the other hand, in order for the light beam to illuminate an area of ± 0.2 mm or more on the left and right of the reading position P as a center, the light beam must enter further than the reading position P by 0.2 mm or more. Since the distance from the side surface of the lens array to the reading position P is represented by φ / 2 + t (φ: diameter of rod lens, t: thickness of side plate), this means that φ / 2 + t + 0.2 mm <s1 + s2.
Indicates that it must be By substituting s1 and s2 into this equation and rearranging, it can be seen that the following relational equation must be satisfied after all.
φ / 2 + t <d × tan (arcsin ((sin30 °) / n)) + (L0′−d) × tan30 ° −0.2 mm
Substituting L0 '= 1.6 mm, d = 1 mm, and n = 1.5 respectively,
φ / 2 + t <0.5mm
Is defined. In the present embodiment, the diameter φ of each rod lens constituting the lens array is reduced to 0.3 mm and the thickness of the side plate is reduced, so that φ / 2 + t becomes 0.45 mm. And the above conditions are satisfied. Thus, the luminous flux emitted from the illumination device can sufficiently illuminate the read position P on the document surface, including a region of ± 0.2 mm or more on the left and right sides. When the rod lens 71 and the side plates 72 and 73 constituting the rod lens array 7 are fixed by an adhesive such as a resin, if the above expression is satisfied in consideration of the thickness of the adhesive. Good.

(Fourth form)
Next, FIG. 11 shows a sectional view of a contact type image sensor of a fourth embodiment. Each component of the present embodiment is basically the same as that shown in FIG. 4, but the lens array 7 is in contact with the cover glass 5 and is held so as to be pressed down by the cover glass 5. The points are different. With such a configuration, it is possible to prevent dust or the like from adhering to the back surface of the cover glass or the surface of the lens array, thereby preventing the reading image quality from deteriorating.

FIG. 12 shows the relationship between the lens array and the illumination light from the illumination device in the present embodiment. The conjugate length TC of the lens array, the height Z0 of the lens array itself, and the distance L0 between the lens array and the surface of the sensor IC are the same as those in the third embodiment. The distance L0 'between the lens array and the document surface is larger, that is, 2 mm because most of the space is occupied by a cover glass having a refractive index of about 1.5.

In order for the illumination light to illuminate an area of ± 0.2 mm or more left and right of the reading position P as a center, the following relational expression obtained as d = L0 ′ must be satisfied.
φ / 2 + t <L0 ′ × tan (arcsin ((sin30 °) / n)) − 0.2 mm
Here, n is the refractive index of the cover glass. Substituting L0 '= 2 mm, d = 1 mm, and n = 1.5, this is again as follows.
φ / 2 + t <0.5mm

Since the diameter φ of each rod lens constituting the lens array of the present embodiment is reduced to 0.3 mm and the thickness of the side plate is reduced, φ / 2 + t becomes 0.45 mm, and the above condition is satisfied. Are satisfied. Thus, the luminous flux emitted from the illumination device can sufficiently illuminate the read position P on the document surface, including a region of ± 0.2 mm or more on the left and right sides.

(Fifth form)
FIG. 13 illustrates a facsimile having a communication function as an example of an information processing device including the contact image sensor according to the present invention described in the above embodiment.

In FIG. 13, reference numeral 100 denotes a reading unit constituted by the contact type image sensor described in each of the above embodiments, 102 denotes a feeding roller for feeding the document PP toward the reading position, and 104 denotes one document PP. This is a separation piece for reliably separating and feeding each piece. Reference numeral 106 denotes a transport roller that is provided at the reading position of the sensor unit 100 and regulates the read surface of the document PP and transports the document PP.

P is a recording paper in the form of a roll paper, on which image information read by the sensor unit 100 or image information transmitted from the outside is formed. The recording paper is not limited to a roll paper, but may be a paper cut to a predetermined size. Reference numeral 110 denotes a recording head for forming an image on the recording paper P, and various types such as a thermal head and an ink jet recording head can be used. The recording head may be of a serial type or a line type.

Reference numeral 112 denotes a platen roller that conveys the recording paper P to the recording position of the recording head 110 and regulates the recording surface thereof. Reference numeral 120 denotes an operation panel provided with switches and buttons for performing operation input by an operator, a message, and a display unit for notifying the status of other devices. Reference numeral 160 denotes a system control board, which includes a control unit for controlling each unit, a driving circuit for a photoelectric conversion element, a processing unit for image information, a transmission / reception unit, and the like. 140 is a power supply of the apparatus.

Next, the basic operation of the facsimile machine will be described. When performing the transmission operation, the operator sets the document PP at a predetermined position, and sets the transmission destination and the transmission mode on the operation panel. When the setting is completed, the document PP is fed to the reading position by the feed roller 102, and reading of image information on the document PP by the reading unit 100 is started. At this time, the document PP is transported while being pressed against the reading unit 100 by the transport rollers 106. When the reading of the document is completed, or in parallel with the reading, the signal is converted into a signal form for sending image data to the other party through a telephone line by the system control board 130 as a signal processing unit and a control unit, and then transmitted.

Conversely, when receiving the image information sent from the other party, the system control board 130 converts the signal into a signal form for forming an image on the recording paper P, and after the conversion, the recording head Images are sequentially formed on the recording paper P by 110 and are discharged by the platen roller 112.

(Sixth form)
The information processing apparatus does not have a recording unit for forming an image other than the facsimile described above, and may be an apparatus such as an image scanner. This embodiment is an example of a configuration in which the image reading device 130 incorporating the above-described contact image sensor 100 is connected to a personal computer 150 to form a system, and the read image information is transmitted to a computer or a network. . In FIG. 14, reference numeral 132 denotes a CPU as first control means for controlling the entire image reading apparatus 130, and 100 denotes a reading unit which includes the above-described light source and CCD line sensor and converts a document image into an image signal. The color image sensor 136 is an analog signal processing circuit that performs analog processing such as gain adjustment on an analog image signal output from the color image scanner 100.

Reference numeral 138 denotes an A / D converter for converting the output of the analog signal processing circuit 136 into a digital signal. Reference numeral 180 denotes a memory 142 using a shading correction process, a gamma conversion process, and a conversion process on the output data of the A / D converter 138. An image processing circuit 144 for performing image processing such as double processing is an interface for outputting digital image data subjected to image processing by the image processing circuit 180 to the outside. The interface 144 conforms to a standard adopted by a personal computer such as SCSI or Bi-Centronics, and is connected to the personal computer 150. The analog signal processing circuit 136, the A / D converter 138, the image processing circuit 180, and the memory 142 constitute a signal processing unit.

The personal computer 150, which is the second control means, is provided with a magneto-optical disk drive, a floppy (registered trademark) disk drive, or the like as the external storage device or the auxiliary storage device 152. 154, a display for displaying work on the personal computer 150; 153, a mouse / keyboard for inputting commands and the like to the personal computer. Reference numeral 155 denotes an interface for exchanging data, commands, and status information of the image reading device between the personal computer and the image reading device.

(4) The personal computer 150 can input a reading instruction to the image reading device from the mouse / keyboard 153. When a reading instruction is input by the mouse / keyboard 153, the CPU 156 transmits a reading command to the image reading device via the interface 155. Then, the personal computer 150 controls the image reading apparatus according to the control program information stored in the ROM 157. Note that the control program may be executed by the CPU 156 by reading a program stored in a storage medium such as a magneto-optical disk or a floppy (registered trademark) disk loaded in the auxiliary storage device 152 into the personal computer 150. .

FIG. 2 is a perspective view of a contact image sensor according to the embodiment. FIG. 2 is a cross-sectional view of the contact type image sensor according to the first embodiment. It is sectional drawing of the contact type image sensor in 2nd Embodiment. It is sectional drawing of the contact type image sensor in 3rd Embodiment. It is a top view of the contact type image sensor in the third embodiment. It is sectional drawing of the illuminating device in 3rd Embodiment. It is a side view of the lighting device in a 3rd embodiment. FIG. 14 is a diagram illustrating characteristics of the lens array according to the third embodiment. It is a figure showing the relation between the lens array and the illumination light of the illumination device in the third embodiment. FIG. 10 is an enlarged view of FIG. 9. It is sectional drawing of the contact type image sensor in 4th Embodiment. FIG. 14 is a diagram illustrating a relationship between a lens array and illumination light according to a fourth embodiment. It is sectional drawing of the information processing apparatus using a contact-type image sensor. 1 is a configuration diagram of an image reading system using a contact image sensor. FIG. 9 is a perspective view of a conventional contact image sensor. It is sectional drawing of the conventional contact type image sensor. It is a perspective view of the conventional rod lens array. FIG. 9 is a diagram illustrating characteristics of a conventional lens array. It is sectional drawing of the conventional contact type image sensor. FIG. 9 is a diagram showing a conventional lens array and its peripheral portion. FIG. 3 is a diagram showing a lens array having a short TC. FIG. 3 is a diagram showing a lens array having a short TC. It is sectional drawing of the contact type image sensor using the lens array with short TC. FIG. 9 is a diagram illustrating a relationship between a conventional lens array and illumination light. FIG. 4 is a diagram illustrating a relationship between a lens array and illumination light when a lens array with a short TC is used.

Explanation of reference numerals

3 Sensor IC
Reference Signs List 4 sensor board 5 cover glass 6 lighting device 7 rod lens array 10 linear image sensor 11 lighting device 71 rod lens 72 side plate 73 side plate 100 reading unit 130 image reading device 150 personal computer 160 system control board PP manuscript

Claims (32)

Used in an image reading device including an illumination device for irradiating a document in a line and a linear image sensor that converts reflected light from the document into an image signal and outputs the image signal, the reflected light is reflected on the linear image sensor. A rod lens array for imaging into
A plurality of rod lenses; first and second side plates for positioning the plurality of rod lenses by arranging and sandwiching the rod lenses from both sides; thicknesses of the first side plate and the second side plate A rod lens array characterized by differentiating. 2. The method according to claim 1, wherein the thickness of the first side plate is smaller than the thickness of the second side plate when the lighting device is disposed with the first side plate interposed between the plurality of rod lenses. Characteristic rod lens array. 3. The rod according to claim 2, wherein, when the diameter of the rod lens is φ [mm] and the thickness of the first side plate is t [mm], φ / 2 + t ≦ 0.5 [mm]. A rod lens array, wherein a diameter of the lens array and a thickness of the first side plate are defined. The rod lens array according to any one of claims 1 to 3, wherein the plurality of rod lenses and the first and second side plates are fixed with resin. Used in an image reading device including an illumination device for irradiating a document in a line and a linear image sensor that converts reflected light from the document into an image signal and outputs the image signal, the reflected light is reflected on the linear image sensor. A rod lens array for imaging into
A rod lens array, comprising: a plurality of rod lenses; and a side plate for arranging and positioning the plurality of rod lenses, wherein the side plate is fixed to only one side of the arrangement of the plurality of rod lenses. The rod lens array according to claim 5, wherein the lighting device is arranged with a plurality of rod lenses interposed between the side plates. The rod lens array according to claim 5 or 6, wherein the rod lens and the side plate are fixed with resin. Used in an image reading device including an illumination device for irradiating a document in a line and a linear image sensor that converts reflected light from the document into an image signal and outputs the image signal, the reflected light is reflected on the linear image sensor. A rod lens array for imaging into
Provided with a plurality of rod lenses, a side plate for arranging and positioning the plurality of rod lenses, when the diameter of the rod lens is φ (mm), and the thickness of the side plate is t (mm), A rod lens array, wherein the diameter of the rod lens array and the thickness of the side plate are defined so that φ / 2 + t ≦ 0.5 [mm]. The rod lens array according to claim 8, wherein the plurality of rod lenses and the side plate are fixed with resin. An illumination device for irradiating the original in a line,
A linear image sensor that converts reflected light from the original into an image signal and outputs the image signal,
A rod lens array configured by arranging a plurality of rod lenses for forming an image of the reflected light on the linear image sensor and sandwiching the first and second side plates having different thicknesses from both sides from both sides;
An image reading apparatus comprising: In Claim 10, when the illuminating device is arranged with a first side plate interposed between the plurality of rod lenses, the thickness of the first side plate is made smaller than the thickness of the second side plate. Characteristic image reading device. 12. The rod lens according to claim 11, wherein when the diameter of the rod lens is φ [mm] and the thickness of the first side plate is t [mm], φ / 2 + t ≦ 0.5 [mm]. An image reading apparatus, wherein a diameter of the first side plate and a thickness of the first side plate are defined. 13. The image reading apparatus according to claim 10, wherein the plurality of rod lenses and the first and second side plates are fixed with resin. An illumination device for irradiating the original in a line,
A linear image sensor that converts reflected light from the original into an image signal and outputs the image signal,
A rod lens array configured by arranging a plurality of rod lenses for imaging reflected light from the subject on the linear image sensor and fixing a side plate to only one side,
An image reading apparatus comprising: 15. The image reading device according to claim 14, wherein the illumination device is arranged with a plurality of rod lenses interposed between the side plates. The image reading apparatus according to claim 14, wherein the rod lens and the side plate are fixed with resin. A transparent member on which the document is placed,
An illumination device for irradiating the original in a line,
A linear image sensor that converts reflected light from the original into an image signal and outputs the image signal,
A rod lens array configured by arranging a plurality of rod lenses for imaging the reflected light on the linear image sensor and positioning the rod lenses by a side plate,
The shortest distance between the surface where the reflected light is incident on the rod lens array and the document surface is L0 [mm], the diameter of the rod lens is φ [mm], the thickness of the side plate is t [mm], and the refractive index of the transparent member is Is n, and the thickness of the transparent member is d [mm],
φ / 2 + t ≦ d × tan (arcsin ((sin30 °) / n)) + (L0−d) × tan30 ° −0.2 [mm]
An image reading apparatus, wherein each member is defined such that 18. The image reading apparatus according to claim 17, wherein φ / 2 + t ≦ 0.5 [mm]. 19. The image reading apparatus according to claim 17, wherein the plurality of rod lenses and the side plate are fixed with resin. An illuminating device for irradiating a document in a line, a linear image sensor for converting reflected light from the document into an image signal and outputting the image signal, and a rod lens for forming an image of the reflected light on the linear image sensor And a rod lens array constituted by arranging a plurality of the lens plates and sandwiching the first and second side plates having different thicknesses from both sides from both sides,
Signal processing means for performing predetermined processing on the image signal output from the image sensor,
An image reading system comprising: 23. The image reading system according to claim 20, further comprising control means for controlling said reading unit and said signal processing means. The thickness of the first side plate is smaller than the thickness of the second side plate when the illuminating device is disposed with the first side plate interposed between the plurality of rod lenses according to claim 20 or 21. An image reading system, comprising: 23. The rod lens according to claim 22, wherein when the diameter of the rod lens is φ [mm] and the thickness of the first side plate is t [mm], φ / 2 + t ≦ 0.5 [mm]. An image reading system wherein a diameter of the first side plate and a thickness of the first side plate are defined. The image reading system according to any one of claims 20 to 23, wherein the plurality of rod lenses and the first and second side plates are fixed with resin. An illuminating device for irradiating a document in a line, a linear image sensor for converting reflected light from the document into an image signal and outputting the image signal, and forming an image of the reflected light from the subject on the linear image sensor A reading unit having a rod lens array configured by arranging a plurality of rod lenses and fixing a side plate to only one side,
Signal processing means for performing predetermined processing on the image signal output from the image sensor,
An image reading system comprising: 26. The image reading system according to claim 25, further comprising control means for controlling the reading unit and the signal processing means. 27. The image reading system according to claim 25, wherein the illuminating device is arranged with a plurality of rod lenses interposed between the side plates. The image reading system according to any one of claims 25 to 27, wherein the rod lens and the side plate are fixed with resin. A transparent member on which the document is placed,
An illumination device for irradiating the original in a line,
A linear image sensor that converts reflected light from the original into an image signal and outputs the image signal,
A reading unit having a rod lens array configured by arranging a plurality of rod lenses for imaging the reflected light on the linear image sensor and positioning the rod lenses by a side plate,
Signal processing means for performing predetermined processing on the image signal output from the image sensor,
With
The shortest distance between the surface where the reflected light is incident on the rod lens array and the document surface is L0 [mm], the diameter of the rod lens is φ [mm], the thickness of the side plate is t [mm], and the refractive index of the transparent member is Where n is the thickness of the transparent member and d [mm], φ / 2 + t ≦ d × tan (arcsin ((sin30 °) / n)) + (L0−d) × tan30 ° −0.2 [ mm]. The image reading system according to claim 29, further comprising control means for controlling the reading unit and the signal processing means. 31. The image reading system according to claim 29, wherein φ / 2 + t ≦ 0.5 [mm]. The rod lens array according to any one of claims 29 to 31, wherein the plurality of rod lenses and the side plate are fixed with a resin.

Images