JP3129991B2 - Imaging element - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an imaging device, and more particularly, to an optical system used in a reading optical system used in a copying machine or a facsimile or a reading scanner used in combination of a CCD line sensor and a 1: 1 sensor. The present invention relates to an imaging element suitable for use in a system or an optical system used for an optical print head or a self-scanning optical print head.

[0002]

2. Description of the Related Art In recent years, downsizing is one of the requirements for devices such as copying machines and optical printer heads. For this purpose, downsizing of a reading optical system or a writing optical system is essential. . In order to meet such a demand, a 1: 1 imaging optical system capable of greatly reducing the object image distance is being studied.

FIG. 16 is a diagram showing a main portion of a conventional optical system for forming an image at the same magnification, in which 1 is a lens array, 2 is a roof mirror array, 3 is a roof mirror lens array, lens for the lens array 1 is 4, the roof mirrors for constituting the roof mirror array 2 5, the ridge of the roof mirror 6, the optical path separating mirror 7, 8, P ₁ is the scanning surface, P ₂ Is an image plane, and φ is an optical axis.

It is known that a roof mirror lens is used as one method of constructing an equal-magnification image forming optical system.
For example, FIG. 17 shows an example of the principle configuration of a unit-magnification imaging element using a roof mirror lens array 3 in which a lens array 1 and a roof mirror array 2 are combined. The roof mirror lens array 3 constitutes an optical system for forming a real-size real image, and a series of optically equivalent lenses 4
A lens array 1 arranged in a row, and a series of roof mirrors 5 having ridge lines 6 orthogonal to the array direction and the lens optical axis direction of the lens array 1
, And a roof mirror array 2 arranged in a line in a one-to-one correspondence with the individual lenses 4 in the above-described configuration, and the individual lenses 4 and the roof are disposed between the lens array 1 and the roof mirror array 2. This is an integral arrangement of an aperture member (not shown) for separating the imaging system by the mirror 5 from each other.

Here, the reading position P _{1 of the} original is set at a finite slit height position that is not on the optical axis φ of the lens 4, the light is converted into substantially parallel light by the lens 4, and then folded in the same direction by the roof mirror 5. The light again passes through the same lens 4 to form an image on an optically conjugate image forming position P ₂ , for example, on a CCD 1 × sensor.

As disclosed in Japanese Patent Publication No. 61-2929, for example, a prism lens array has a lens array and a roof mirror array integrated with each other. The reading position is set at the slit height position, and after the reflected light passes through the lens surface, it is reflected by the roof prism twice, passes through the lens surface again, and forms an image at a conjugate position.

The roof mirror lens array is an "optical system for forming a real-size real image".
Various types of lenses, such as those disclosed in Japanese Patent Application Publication No. 26-26, are known. A "lens array" in which a series of lenses equivalent to an optical system are arranged in a line, and a lens array in this lens array A roof mirror array in which a series of roof mirrors having ridges perpendicular to the direction and the optical axis of the lens are arrayed in a one-to-one correspondence with the individual lenses in the lens array; A "stop member" is provided between the mirror array and separates the imaging system of the lens and the roof mirror from each other. I have.

In any case, in this type of imaging element, an arbitrary lens in the lens array forms one imaging system with a corresponding roof mirror, and each aperture of the diaphragm member is Need to be positioned corresponding to each of these imaging systems and to optically separate the imaging systems from each other. In other words, with this type of imaging element, it is impossible to lay out the reading position and the imaging position at the same position because the same lens is reciprocated and passed, and the light beam on the optical axis In order to separate the light flux on the (original surface) side and the light flux on the imaging surface (CCD equal magnification sensor) side, a finite slit height must be used. That is, to set the position P ₁ read on the finite image height position in the direction of the ridge 6 of the roof mirror 5, an imaging position P _2, it is necessary for forming the minus image height position of. However, since the amount of separation is limited, the optical path is actually turned back by the optical path separating mirrors 7 and 8 as shown in FIG. The optical path separating mirrors 7 and 8 shown in FIG. 17 are strip-shaped plane mirrors that are long in the front and back directions of the paper surface, and are disposed at an angle of 45 ° with respect to a plane sharing the optical axis φ of each lens 4 of the lens array 1. I have.

FIG. 17 is a view showing an example of an imaging element which is cited as a conventional example in Japanese Patent Publication No. 5-53245. FIG. 17 (A) is a front view, FIG. 17 (B) is a side view,
FIG. 17C is a bottom view, in which 11 is an object-side lens array, 12 is an imaging-side lens array, 13 is a roof prism array, and this imaging element has two lens arrays as shown. 11 and 12, and a ridge line 1 perpendicular to the array direction of the lens arrays between the lens arrays.
4 is a roof prism lens array imaging element including a roof prism array having the same pitch as the pitch of the lens array. In this roof prism array imaging device, the light beam from the incident side passes through the lens array 11, is reflected twice by the roof prism array 13, and is located at the same position as the lens array 11 and the roof prism array 13. 12 and an image is formed. In the arrangement direction, since an erect real-size real image is obtained by the retroreflection function of the roof prism, it is possible to form an equal-size real image of a required width by overlapping the images in the arrangement direction. Further, as an imaging element having the same function, the roof prism array 13 is constituted by a roof mirror array, and a roof mirror lens array having a structure in which the roof mirror array and the lens arrays 11 and 12 are integrated. Image elements are also known.

[0010] However, the roof prism lens array imaging device shown in FIG. 17, as shown in FIG. 17, there are light beams L ₁ intersecting between adjacent lenses, the light beam is an imaging light imaging It appears on the image plane and becomes so-called ghost light, which causes a problem. Also within the same lens system, there is a light beam L ₂ reflected only on one side of the roof prism, there is a problem that the flare.

FIG. 19 is a perspective view showing an example of a roof prism lens array imaging device disclosed in Japanese Patent Publication No. 5-53245. In the drawing, reference numeral 11 denotes an object-side lens, 12 denotes an imaging-side lens, and 13 denotes a lens. Is a prism, 14 is a ridge line, 15 is a roof surface (reflection surface), 16 is a notch groove, and as shown in the figure, two surfaces A and B arranged at right angles to the prism 13 are objects. Side lens 11 and imaging side lens 12
Are formed, and a plurality of roof surfaces 15 are provided so as to connect end sides of the two surfaces. A cutout groove 16 for blocking light from the next is provided at least in a portion where light passes between the plurality of roof surfaces 15, and by providing the cutout groove 16,
The resolution is made extremely good by preventing light incident on the lens from entering the adjacent lens inside, thereby preventing flare and stray light from occurring.

[0012]

FIG. 20 is a schematic diagram for explaining a problem to be solved by the roof prism lens array shown in FIG. 19, and as shown in FIG.
The roof prism lens array includes an object side lens 11
And a roof surface (prism) 15 and an image-forming side lens 12, and a notch groove 16 for shielding light between adjacent roof surfaces.
As shown in FIG. 20, if there is a light beam L ₁ incident at an acute angle at the interface with the cutout groove 16, which is defective appearing on the imaging plane becomes ghost light. Further, even in the same lens system, there is a light beam L ₂ reflected only on one side of the roof prism, which is defective as a flare. Note that FIG.
In FIG. 1, the object-side lens and the image-side lens are drawn on the same plane for easy explanation.
The content is not different from the defect in the configuration shown in FIG.

As described above, the conventional roof mirror (or prism) lens array has one-time reflected light on the roof mirror surface that occurs in a region where the angle of view in the arrangement direction is large, and differs between the incident side and the image forming side. Crosstalk ghost light passing through the lens at the array position forms an image on the image plane at a position different from the normal image forming position and does not form an overlapping image in the array direction, so that the image quality, contrast, resolution, etc. are reduced. Is a factor.

The present invention has been made in view of the above-mentioned circumstances, and in an imaging element using a roof mirror array or a roof prism array as described above, it is desired that the ghost light reaches the imaging surface. It is noted that crosstalk ghost light between adjacent lenses is reflected effectively near the ridge / valley between the optical axes of the arrangement of the roof mirror or the roof prism which is the reflection surface. The crosstalk ghost light is prevented by changing the shape and the reflection characteristics near the part, thus achieving high light use efficiency and
It is intended to improve the imaging performance while maintaining the uniformity of the light amount distribution.

[0015]

According to the first aspect of the present invention, there is provided a first lens array in which a series of optically equivalent lenses are arranged in a line and located on the incident side, and the first lens array and the optical system. A second lens array formed on the image-forming side, which is formed equivalently to each other, and a roof mirror array having ridge lines between these lens arrays orthogonal to the array direction of the lens arrays at the same pitch as the pitch of the lenses If, have a aperture array arranged in correspondence with the with the roof mirror array first and second lens arrays, the roof
The area near the ridge between the optical axes of the mirror array is
It is characterized in that it has a shape that is notched by a surface or a curved surface .

According to a second aspect of the present invention, in the first aspect of the present invention, a surface near a ridge between the optical axes of the roof mirror array is roughened or a light absorbing member. .

According to a third aspect of the present invention, there is provided a first lens array in which a series of optically equivalent lenses are arranged in a line and located on the incident side, and formed optically equivalent to the first lens array. A second lens array positioned on the image-forming side, and having a plane forming 90 ° with respect to each other and forming a ridge line, on a plane including both optical axes of the lens, and at a position where the optical axes intersect. possess a roof prism array having a roof prism ridge lines are arranged at a pitch the same pitch as the lens, an aperture array arranged in correspondence with the with the roof prism array first and second lens array, Previous
Near the valley between the optical axes of the roof prism lens array
Are formed in one or more flat surfaces or curved surfaces .

The invention according to claim 4 is the invention according to claim 3.
And a valley between the optical axes of the roof prism lens array.
The surface near the portion is roughened or a light absorbing member .

The invention of claim 5 is the invention according to claim 3.
And a valley between the optical axes of the roof prism lens array.
At least a part of the lens unit is incident from a certain lens unit and
The light reflected by the roof prism corresponding to the
In order to reduce the luminous flux emitted from the adjacent imaging system,
Has the same refractive index as the roof prism
It is characterized by being filled with a transparent member .

The invention according to claim 6 is an optically equivalent incident side.
The lens unit and the imaging side lens unit and the ridge line 90
° and includes both optical axes of the lens unit
The ridge line is arranged at a position where the optical axis intersects on a plane.
Roof prism integrated with the roof prism section
And the roof prism lens on the ridge line.
Roof pres that are arranged in a single row in a direction perpendicular to
Lens array and the roof prism lens array
An aperture is provided on the front of the entrance lens and the imaging lens.
An aperture array disposed on the roof prism;
The vicinity of the valley between the optical axes of the lens array
It is characterized by being formed on a surface or a curved surface .

According to a seventh aspect of the present invention, in the sixth aspect of the invention, the surface near the valley between the optical axes of the roof prism lens array is roughened or a light absorbing member. is there.

According to an eighth aspect of the present invention, in the sixth aspect of the present invention, at least a part of a valley between the optical axes of the roof prism lens array is incident from a certain lens portion and the roof corresponding to the lens portion. In order to reduce the luminous flux reflected by the prism portion from the adjacent imaging system, a transparent member having a refractive index substantially equal to the refractive index of the roof prism portion is filled.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a view showing the configuration of a main part for explaining an embodiment of an imaging element according to the present invention. FIG. 1A shows a conventional imaging optical system to which the present invention is applied. Partial schematic perspective view,
1B is a partially cut perspective view of an aperture member added according to the present invention, and FIG. 1C is an imaging optical system shown in FIG. 1A and an aperture member shown in FIG. In the figure, 21 and 22 are a light-collecting element (lens) array, 23 is a roof mirror array, 24
Are aperture members added according to the invention, 25,2
6 is a light-collecting element (lens), 27 is a ridge line, 28 and 29 are reflection surfaces (dach surfaces), 30 is a roof mirror, 31 and 32 are openings, and φ is an optical axis.
Thus, the above-mentioned ghost light is prevented.

As shown in FIG. 1, the imaging element according to the present invention comprises a first lens array 21 located on the incident side, a second lens array 22 located on the imaging side, and these lens arrays. A roof mirror array 23 located between the lens arrays 21 and 22 and an aperture member 24 as an aperture member located between the lens arrays 21 and 22 and the roof mirror array 23 are combined.

First, the first lens array 21 is formed by arranging a series of optically equivalent lenses 25 in a row at an equal pitch in the array direction. Further, the second lens array 22 is structurally similar to the first lens array 2.
A series of lenses 26 identical to 1 and optically equivalent
Are arranged in a line at an equal pitch in the array direction. The roof mirror array 23 includes lenses 25, 2
The ridge line 27 is formed at the position where the optical axes of 6 cross each other.
A roof mirror 30 having two reflecting surfaces (planes) 28 and 29 forming 0 ° is continuously arranged in the array direction corresponding to these lenses 25 and 26. Here, this roof mirror array 23
Are arranged at an angle of 45 ° with respect to the lens arrays 21 and 22.

In the above-described configuration, the optical axis of each lens 25 includes the ridge line 27 of the roof mirror 30 and is on a plane perpendicular to the array direction. The light becomes parallel light and enters the corresponding roof mirror 30. After being reflected twice by the planes 28 and 29 of the roof mirror 30, it is bent twice, that is, 90 °, with respect to the inclination angle of the ridge line 27 (here, 45 °), and is bent toward the second lens array 22. To the corresponding lens 26. Then, the light is condensed and formed on the image forming surface by the lens 26. Since the lens 26 is optically equivalent to the lens 25 and has the same light-condensing function, it has an optimal image forming surface at a position opposite to the reading position on the document surface. In such an imaging process,
Since the light is reflected twice by each roof mirror 30, the formed image is an erect equal-size image. In this case, the single effective reading width by the individual lenses 25 and 26 overlaps each other while being shifted by their arrangement pitch, thereby covering the required effective width. This allows
The focal length of each of the lenses 25 and 26 can be shortened, which contributes to downsizing as an imaging element.

The aperture member 24 is added according to the present invention. The aperture member 24 prevents the crosstalk light between the adjacent lenses 25 and between the lenses 26 to optimize the resolving power and the light amount. The apertures 3 are arranged at an equal pitch to the arrangement pitch of the lenses 25 and 26 in the first and second lens arrays 21 and 22.
1, 32 are formed. Although the aperture member 24 is provided inside the lens in the illustrated example, it may be provided outside the lens, or the lens may be provided inside the aperture member.

FIG. 2 schematically shows the structure of the imaging element shown in FIG. 1. FIG. 2 (A) is a sectional view of a main part, and FIG. Partial cross-sectional view, FIG.
FIG. 1C is a view as viewed in the direction of arrow C in FIG. 1A. As described above, the light beam from the incident side (original surface) is
1, pass through the lens array 25, and
The lens 2 of the lens array 22 which is reflected twice and located at the same position as the lens array 21 and the roof mirror array 23
6, and passing through the aperture 32 to form an image.

FIG. 3 is a sectional view of an essential part for explaining the operation of the aperture member 24. As shown, stray light L ₁ and L ₂ pass through the aperture 31 of the aperture member 24 and the roof 25 through the lens 25. The light impinges on the mirror 28 (29) and is reflected by the reflection surface 28 (29) of the roof mirror 23 and proceeds in the direction of the lens 25 or 26. At this time, the light hits the side wall surface or the bottom surface of the aperture member 24 and is blocked. Irrespective of the image formation, the imaging performance is not degraded.

FIG. 4 is a diagram schematically showing the light blocking function shown in FIG. 3. As described above, by providing the aperture member, the light amount distribution in the arrangement direction is made uniform, and the angle of view in the arrangement direction is increased. Prevention of once-reflected light on the roof mirror surface occurring in the area (L _{1 in} FIG. 3), and prevention of crosstalk ghost light passing through lenses of different arrangement positions on the incident side and the imaging side (L _{2 in} FIG. 3). The following three functions can be provided. Thus, the above-mentioned light rays form an image at a position different from the normal image forming position on the image forming surface and do not form an overlapping image in the arrangement direction, so that the light becomes ghost light, and the image quality, contrast,
The aperture shape should be optimized so as to maximize the functions of,,, and so on, because it causes a decrease in resolution and the like. However, light rays can be relatively easily prevented by an aperture with a wide aperture. Although it is possible, the aperture of the aperture must be extremely small in order not to generate the crosstalk ghost light at all, and there is a problem that the light use efficiency is remarkably reduced. This can be solved by increasing the length of the aperture, as shown by the dashed line inside.

FIG. 5 is a schematic view for explaining another example of the image forming element according to the present invention. This image forming element cuts a ridge between the optical axes of the roof mirror array 23 by two planes. The stray light L ₁ is cut off by the wall surface of the aperture 32 because the shape of the cutout is such that the reflection surface of the notch and the ridge line portion is deleted. This deleted shape does not necessarily have to be formed from two planes, and the layout of the lens array, roof mirror array,
What is necessary is just to form by the optimal surface for preventing crosstalk ghost light by the opening shape of an aperture.

As shown in FIG. 4C, crosstalk ghost light generated between adjacent lenses is reflected by the roof mirror.
As shown in FIG. 5, the light is reflected once by changing the shape of the reflection surface at the ridge between the optical axes of the roof mirror array, so that the light is reflected once at another angle on the newly formed surface. be able to. This one-time reflected light does not enter the aperture opening on the image forming side because the reflecting surface has certain angles θ ₁ and θ ₂ with respect to the angle of the roof mirror, and does not reach the image forming surface, so that it does not become crosstalk light. In addition, the normal imaging light does not use the reflection surface near the ridge between the optical axes of the roof mirror array, so it is not affected by the shape change.
Only the crosstalk ghost light can be prevented without lowering the light amount distribution uniformity.

FIG. 6 is a schematic diagram for explaining another example of the image forming element according to the present invention. In this image forming element, the ridge between the optical axes of the roof mirror array 23 is shown in FIG. As shown in an enlarged manner in C), it has a curved surface (cylindrical curved surface) R, and has a shape in which the reflection surface of the ridge portion is deleted. This deleted shape does not necessarily have to be formed from a cylindrical curved surface, and the layout of the lens array, roof mirror array,
What is necessary is just to form by the optimal surface according to the opening shape of an aperture. In this manner, by making the reflection surface shape of the ridge between the arrayed optical axes of the roof mirror array a curved surface, the irradiated light flux is diffusely reflected, and the reflected light passes through the aperture opening on the image forming side to form the image forming surface. Does not form an image even if the number of light beams reaches the threshold value, the light does not become ghost light, and crosstalk ghost light can be prevented without lowering the light use efficiency and the uniformity of the light amount distribution.

FIG. 7 is a schematic diagram for explaining another embodiment of the imaging element according to the present invention.
As shown in FIG.
The ridge between the arrayed optical axes is roughened, or the light absorbing member S is provided on the ridge. In this way, the luminous flux can be irregularly reflected by roughening the reflection surface at the ridge between the optical axes of the roof mirror array. This diffusely reflected light does not form an image even if it reaches the image forming plane after passing through the aperture opening on the image forming side, and does not become ghost light. The normal imaging light does not use the reflection surface near the ridge between the optical axes of the roof mirror array, so it is not affected by the rough surface, and the crosstalk ghost does not reduce the light use efficiency and the uniformity of the light amount distribution. Light can be prevented. Further, when a light absorbing member is provided on the reflection surface at the ridge between the arrayed optical axes of the roof mirror array, the light flux is absorbed by the surface and no reflection occurs, so that the light use efficiency and the uniformity of the light amount distribution are not reduced. Therefore, crosstalk ghost light can be prevented.

FIG. 8 is a main part configuration diagram for explaining another embodiment (an example in which a roof prism is used in place of the roof mirror) according to the present invention. FIG. FIG. 8B is a perspective view of a roof prism lens array, FIG. 8B is a perspective view of an aperture member, FIG. 8C is a side view when the roof prism lens array and the aperture member are combined, and FIG. 8 is a diagram schematically showing the imaging element shown in FIG. 8, in which 41 is a roof prism lens array,
42 is an aperture member, 43 is a roof prism lens,
44 is a light entrance side lens unit, 45 is an image formation side lens unit, 46 is a ridge line, 47 and 48 are flat surfaces (reflection surfaces), 49 is a roof prism unit, 50 and 51 are apertures, and φ ₁ and φ ₂ are optical axes. In this embodiment, a single roof prism lens array 4 replaces the roof mirror array and the lens array described above.
No. 1 is used, and the image forming operation is the same as that of the above-described example using the roof mirror array. The figure shows an example in which the roof prism lens array and the lens array are formed integrally, but these are formed separately, and the roof prism array is used by functioning in the same manner as the roof mirror array. That is easy to understand.

The image forming element shown in FIG. 8 includes a roof prism lens array 41 and an aperture member 42 serving as an aperture member.
Are combined. Here, the roof prism lens array 41 is configured by arranging roof prism lenses 43 that individually form an imaging system in a single row. The roof prism lens 43, which is the minimum unit of the image forming system, has an optically equivalent incident side lens portion 44, an image forming side lens portion 45, and flat surfaces 47, 48 forming 90 degrees with each other and forming a ridge line 46. The lens units 44 and 45 are integrally formed with a roof prism unit 49 disposed at a position where the optical axes intersect, and the optical axes φ ₁ and φ ₂ of the lens units 44 and 45 are integrally formed. Are orthogonal to each other and on a plane including these optical axes φ ₁ and φ ₂ , where the optical axes φ ₁ and φ ₂
The ridge line 46 located at the position where the optical axis φ intersects
_1, is inclined 45 degrees with respect to phi _2. Therefore, the array direction of the roof prism lens array 41 is set to a direction orthogonal to the ridge line 46. The aperture member 42 has openings 50 and 51 formed at the same pitch as the arrangement pitch of the lens portions 44 and 45 in the roof prism lens array 41.

In the above-described configuration, the optical axis of each of the incident side lens portions 44 is aligned with the ridge line 4 of the roof prism portion 49.
The light information from the document surface on the plane including the image plane 6 and orthogonal to the array direction is converted into parallel light by the incident side lens unit 44 and enters the corresponding roof prism unit 49.
In the roof prism section 49, two planes 47 and 48
After being reflected twice, the inclination angle of the ridge line 46 (here, 45
゜) is folded twice, that is, 90 °,
The light exits from the imaging side lens unit 45. The light is focused and formed on the image forming surface by the image forming side lens unit 45. Since the image forming side lens portion 45 is optically equivalent having the same light condensing function as the incident side lens portion 44, it has an optimum image forming surface at a position opposite to the reading position on the document surface. are doing. Also,
In such an image forming process, each roof prism section 49
Is reflected twice, the image formed is an erect equal-magnification image. In this case, the single effective reading width by the individual lens units 44 and 45 overlaps each other while shifting by the arrangement pitch, thereby covering the necessary effective width. As a result, the focal lengths of the individual lens portions 44 and 45 can be shortened, which contributes to downsizing as an imaging element.

[0038] In this imaging device, as shown in FIG. 3, even if the stray light L _1, L _2, as described in FIG., Adversely affect the imaging beam, the aperture in this case Since the member 42 is provided, such an adverse effect can be reliably prevented.

FIG. 10 is a view showing the construction of a main part of another embodiment of the imaging device according to the present invention.
Is an aperture member. In this embodiment, the lens portions 44 and 4 are provided.
5 are formed so as to be clearly distinguished from each other, and aperture members 53 and 54 are provided separately for each lens portion. Other portions having the same operation as in FIG. 9 are denoted by the same reference numerals as in FIG. is there.

FIG. 11 is a view showing the construction of a main part of another embodiment of the imaging element according to the present invention. In FIG. 11, reference numeral 61 denotes a roof prism lens array, 62 and 63 denote aperture members, and 64 denotes a roof prism. Lens, 65 is a lens section, 6
5a and 65b are lenses, 66 is a ridge line, 67 is a plane, 68
Is a roof prism section, and 69 and 70 are apertures. This imaging element is configured by combining a roof prism lens array 61 and aperture members 62 and 63 as aperture members. Here, the roof prism lens array 61
Is a roof prism lens 64 that individually forms an imaging system.
Are arranged in a line. The roof prism lens 64, which is the minimum unit of the imaging system,
One lens part 65 and a roof prism part 68 having a plane 67 (only one side is shown) forming 90 ° and forming a ridge line 66 are integrally formed. The lens section 65 has an incident-side lens 65a and an imaging-side lens 65b that are set in directions in which the optical axes φ ₁ and φ ₂ are different, here, directions that are orthogonal to each other and exhibit an optically equivalent light-collecting function. ing. The ridge 66 of these optical axes phi _1, phi ₂ optical axis phi ₁ a on the plane including, of the position where phi ₂ is cross the optical axis phi
_1, are disposed inclined 45 ° with respect phi _2. Therefore,
The array direction of the roof prism lens array 61 is set to a direction orthogonal to the ridgeline 66. The aperture members 62 and 63 have openings 69 at the same pitch as the arrangement pitch of the lenses 65a and 65b in the lens portion 65.
70 are formed.

In such a configuration, the optical axis of each of the incident side lenses 65a is on a plane including the ridge line 66 of the roof prism section 68 and orthogonal to the array direction. The light is converted into parallel light by 65a and enters the corresponding roof prism section 68. After being reflected twice by the two planes 67 in the roof prism section 68, the same lens section 65 is bent twice, that is, 90 °, with respect to the inclination angle of the ridge 66 (here, 45 °). Out of the different interface, ie, the imaging side lens 65b. The light is focused and imaged on the image forming plane by the image forming side lens 65b. Since the imaging side lens 65b is optically equivalent having the same light condensing function as the incident side lens 65a, it has an optimum imaging surface at a position opposite to the reading position on the document surface. . Further, in such an image forming process, since the light is reflected twice by each roof prism section 68, the image formed is an erect equal-size image. In this case, the single effective reading width by the individual lenses 65a and 65b covers the necessary effective width by overlapping each other while shifting by the arrangement pitch. Thus, the focal length of each of the lenses 65a and 65b can be reduced, which contributes to downsizing as an imaging element.

By providing a transparent member having a refractive index close to the refractive index of the roof prism array integrally or by coating it between the valleys between the optical axes of the roof prism array as described above, Such stray light can be removed without reflecting such stray light without guiding it to the imaging lens. FIG. 12 shows this valley as a curved surface (R surface) 41.
FIG. 13 is a schematic configuration diagram when formed in R, and FIG.
FIG. 14 is a schematic configuration diagram when S is provided, and FIG.
FIG. 7 is a schematic configuration diagram in the case of “1”. Note that a light absorbing member may be applied instead of the roughened surface 41T. Thus, stray light can be removed by making the valley a curved surface, a light transmitting surface, a roughened surface, and a light absorbing surface.

FIG. 15 shows a configuration in which the vicinity of the valley between the optical axes of the roof prism array as described above is cut out on two planes and filled with the same material as the prism.
FIG. 15B is a diagram for explaining an operation when an aperture array is provided in front of the first lens array and the second lens array, which is formed by integral formation or the like. FIG. sectional view showing a state of light L ₁ which is a sectional view showing a state shown in FIG. 15 (C) the light L ₂ having passed through, by mirror-finishing a notch surface, it is also possible to transmit suppress reflected light is there.

In FIG. 15, when the height of the aperture is reduced, the light beam incident on the adjacent prism (shown by a broken line)
Even though it appeared, as indicated by the solid line in FIG. 15 (A), not being reflected by the notched face L _1, and the ghost light. In addition, the notch surface is mirror-finished, so that FIG.
As shown by the dashed line in (B), the light can be transmitted (L ₂ ), and stray light can be further suppressed (the broken line shows the state of stray light when no cutout surface is provided). By adopting the above configuration, the degree of freedom in designing the aperture shape is improved, and the angle of view of the imaging element can be increased. Further, the aperture opening shape can be made large, and the light use efficiency can be increased.

[0045]

The roof mirror (or prism) adjacent to the roof mirror
And stray light that becomes a problem in the related art, such as stray light that passes through an adjacent imaging side lens and stray light that is once reflected by one surface of a roof mirror (or prism) in the same lens system.
By providing the aperture array, it is possible to reliably prevent this. Furthermore, a roof mirror array, or
By cutting out the vicinity of the ridge of the roof prism array with a flat surface or a curved surface, or using a roughened surface or a light absorbing member, stray light can be more reliably prevented.

[Brief description of the drawings]

FIG. 1 is a main part configuration diagram for explaining an embodiment (an example using a roof mirror) of an imaging element according to the present invention.

FIG. 2 schematically shows a configuration of the imaging device shown in FIG.

FIG. 3 is a sectional view of a main part for describing the operation of the aperture member.

FIG. 4 is a diagram schematically showing a light blocking function shown in FIG. 3;

FIG. 5 is a schematic diagram for explaining another example of the imaging element according to the present invention.

FIG. 6 is a schematic diagram for explaining another example of the imaging element according to the present invention.

FIG. 7 is a schematic diagram for explaining another embodiment of the imaging element according to the present invention.

FIG. 8 is a main part configuration diagram for explaining another embodiment (an example using a roof prism) of the imaging element according to the present invention.

FIG. 9 is a diagram schematically showing the imaging element shown in FIG. 8;

FIG. 10 is a main part configuration diagram for explaining another embodiment of the imaging element according to the present invention.

FIG. 11 is a main part configuration diagram for explaining another embodiment of the imaging element according to the present invention.

FIG. 12 is a schematic configuration diagram when a valley is formed on a curved surface (R surface).

FIG. 13 is a schematic configuration diagram when a light transmitting member is provided in a valley.

FIG. 14 is a schematic configuration diagram in a case where a valley is made a rough surface.

FIG. 15 is a diagram illustrating an operation in the case where the vicinity of a valley between the optical axes of the roof prism array is cut off by two planes.

FIG. 16 is a main part configuration diagram for explaining an optical system for imaging at the same magnification according to the related art.

FIG. 17 is a diagram showing an example of an imaging element cited as a conventional example in Japanese Patent Publication No. 5-53245.

FIG. 18 is a diagram for explaining a cause of generation of stray light.

FIG. 19 is a diagram illustrating an example of an imaging element described in Japanese Patent Publication No. 5-5324.

20 is a schematic view for explaining a problem to be solved in the roof prism array shown in FIG.

[Explanation of symbols]

Reference numeral 21: incident side lens array, 22: imaging side lens array, 23: roof mirror array, 24: aperture member, 25, 26: lens, 27: ridge line, 28, 29: reflection surface, 30: roof mirror, 31, 32 ... Aperture,
41: roof prism lens array, 42: aperture member, 43: roof prism lens, 44: light entrance side lens, 45: image formation side lens, 50, 51: aperture.

────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Narika Misawa 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Company, Ltd. (72) Inventor Ikuo Maeda 1-3-6 Nakamagome, Ota-ku, Tokyo No. Ricoh Co., Ltd. (72) Inventor Takato Uga 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (56) References JP-B Hei 5-53245 (JP, B2) Akira Tokubo 61-2929 (JP, B2) (58) Fields investigated (Int. Cl. ⁷ , DB name) G02B 27/18

Claims (8)

(57) [Claims] 1. A first lens array having a series of optically equivalent lenses arranged in a line and located on an incident side, and a first lens array formed optically equivalent to the first lens array and located on an image forming side. A second lens array, a roof mirror array having ridges perpendicular to the array direction of the lens arrays between the lens arrays at the same pitch as the pitch of the lenses, the roof mirror array, and the first and second lens arrays; Second
Have a aperture array arranged in correspondence with the lens array, ridge between sequences optical axis of the roof mirror array
The shape of the neighborhood cut out with one or more flat or curved surfaces
An imaging element characterized in that: 2. The imaging device according to claim 1, wherein a surface near a ridge between the optical axes of the roof mirror array is roughened or a light absorbing member. 3. A first lens array having a series of optically equivalent lenses arranged in a line and located on an incident side, and a first lens array formed optically equivalent to the first lens array and located on an image forming side. The second lens array is located, and the ridge line is disposed at a position where the optical axis intersects on a plane including both optical axes of the lens and having a plane forming 90 ° with each other and forming a ridge line. possess a roof prism array having a roof prism pitch and equal pitch of the lens, an aperture array arranged in correspondence with the with the roof prism array first and second lens arrays, the roof prism
One or more planes near the valley between the optical axes of the lens array
Or an imaging element formed on a curved surface. 4. An arrangement of the roof prism lens array.
The surface near the valley between the optical axes is roughened or a light absorbing member
The imaging device according to claim 3, wherein: 5. An arrangement of the roof prism lens array
At least a part of the valley between the optical axes enters from a certain lens part.
And is reflected by the roof prism corresponding to the lens.
Reduces the luminous flux emitted from the adjacent imaging system
Therefore, the refractive index is almost the same as the refractive index of the roof prism section.
A transparent member having a modulus is filled.
4. The imaging element according to 3. 6. An optically equivalent incident side lens portion and an image forming side.
Shape lens and ridge Have planes at 90 ° to each other
Light on a plane including both optical axes of the lens unit.
A roof prism in which the ridge is arranged at a position where a shaft intersects
And a roof prism lens that integrates the
Move the roof prism lens in a direction perpendicular to the ridgeline.
Roof prism lens array arranged in a line as a body
And an entrance side lens portion of the roof prism lens array.
An aperture with an aperture in front of the imaging side lens
A roof array, and the roof prism lens array.
Convert the vicinity of the valley between the arrayed optical axes into one or more planes or curved surfaces
An imaging element characterized by being formed. 7. The imaging element according to claim 6 , wherein a surface near a valley between the optical axes of the roof prism lens array is roughened or a light absorbing member. 8. An imaging system in which a light beam incident from a certain lens portion and reflected by a roof prism portion corresponding to the lens portion is adjacent to at least a part of a valley portion between optical axes arranged in the roof prism lens array. claims in order to reduce the light flux emitted, and wherein the filled transparent member having a refractive index substantially the same refractive index of the roof prism portion from
7. The imaging element according to 6 .