JPH0727996A - Imaging element - Google Patents

Abstract

PURPOSE:To provide an imaging element which does not require particularly difficult know-how, is easily produced, easily usable and small in chromatic aberration. CONSTITUTION:Two columnar transparent bodies 1, 2 formed by forming or disposing convex lenses on the other side to a steep angle of the first columnar transparent body having two sides crossing each other at the steep angle are symmetrically placed in such a manner that the convex leness exist on the outer sides. The two second columnar transparent bodies 3, 3 having the two sides proximate to the sides and the side on which another one reflection surface 4 is formed or the second columnar trnansparent body integrated with two of such bodies is disposed to form an imaging unit. These imaging units are lined up in an array form so as to face prism surfaces to constitute the imaging element.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming element used in facsimiles, electronic copying machines, LED printers and the like.

[0002]

2. Description of the Related Art In facsimiles, copiers, LED printers, etc., an image forming element for projecting an object on a line onto a sensor or a photosensitive drum at an equal magnification is used. An imaging element used in this field is a cylindrical transparent body,
A lens array in which a large number of rod-shaped lens elements whose refractive index continuously decreases from the axis to the outside are arranged in parallel, for example, JP-B-49-8893 and JP-A-57-1049.
No. 23, Japanese Unexamined Patent Publication No. 57-66414, etc., in which convex lens arrays are laminated in a multilayer structure,
JP-A-61-210319, JP-A-56-117
201, JP-A-56-126801, JP-A-56-140301, and JP-A-56-14900.
No. 2, JP 60-254018 A, JP 6
No. 0-254019, Japanese Patent Laid-Open No. 60-254020, Japanese Patent Laid-Open No. 61-233714, Japanese Patent Laid-Open No. 62-
No. 91902 and Japanese Patent Application Laid-Open No. 62-201417, the optical prism units (or roof mirrors) and lenses are combined to form an erecting equal-magnification image, and the optical system units are arranged in an array. Things, etc. are known.

[0003]

The imaging element using the gradient index rod lens described above requires a long time to manufacture the gradient index rod lens, and the integration of the refraction angles of the rays is large, resulting in chromatic aberration. Is likely to occur, and it is difficult to control the refractive index distribution within the cross section of the rod-shaped lens, which makes it difficult to manufacture.

Further, the above image forming element does not cause any difficulty in manufacturing the convex lens array itself, but it is difficult to realize high resolution because aberrations of three or more lenses are integrated. There is a difficulty in the assembling process in which the axes of the lenses of the respective layers are accurately aligned, and the chromatic aberration is large because the integration of the refraction angles of the light rays becomes large.

Further, since the above-mentioned image forming element has a special shape in which the optical path is changed by the reflecting means placed between the lens and the object plane and the image plane, the position and direction of the illumination light are adjusted accordingly. There is a problem that it is difficult to use because it is necessary to optimize the above, and if the alignment of the roof prism (or roof mirror) and the lens is not accurately performed, uneven brightness occurs.

Therefore, a first problem to be solved by the present invention is to provide an imaging element which does not require particularly difficult know-how, is easy to manufacture and is easy to use, and has small chromatic aberration. Further, in the contact image sensor using the image forming element, a single line image sensor using a large-area semiconductor film or a plurality of short line image sensors are used side by side, but especially when the reading width is long. It is difficult to cover the entire reading length with a single line image sensor like the former, and it is unavoidable to use multiple line image sensors. When using multiple line image sensors connected in this way, it is difficult to arrange them so that the light receiving surfaces of adjacent line image sensors are in contact with each other without any gaps. As a result, a read line shift occurs, and it is necessary to correct this in a circuit manner.

Further, even in an LED printer or a liquid crystal printer, it is not technically easy to make an LED array or a liquid crystal shutter having a length equal to the print width. This is unavoidable as long as the conventional imaging optical system in which the subject and the image correspond one-to-one is used. Therefore, a second problem to be solved by the present invention is to provide an image-forming element in which a subject and an image correspond one-to-many or many-to-one. In the contact image sensor, this allows images on one line to be connected to two or more lines, and the line image sensor arranged in a staggered manner on these lines makes it possible to read the image on the same line. No line correction is required. Also, in LED printers and liquid crystal printers, LEs arranged in a zigzag pattern on a plurality of lines and having a short length
Since a complete one-line image can be formed by connecting the images of the D array and the liquid crystal shutter on the same line, it is possible to use the LED array and the liquid crystal shutter of which the length is easy to manufacture.

[0008]

The first and second inventions of the present application were devised to solve the above-mentioned first problem. An imaging element according to the first invention has two side surfaces intersecting at an acute angle. Two of the first columnar transparent body having a convex lens formed or arranged on the other side face with respect to the acute angle are placed symmetrically so that the convex lens is on the outside, and two side faces close to the side face are provided. , An imaging unit comprising two columnar transparent bodies each having a side surface on which another reflecting surface is formed, or a second columnar transparent body in which the two are integrated, is provided to face the reflecting surface. Are arranged in an array.

The imaging element according to the second aspect of the present invention comprises a first columnar transparent body having two side surfaces intersecting at an acute angle, and two convex side lenses formed or arranged on the other side surface with respect to the acute angle. Two convex side surfaces are placed symmetrically so that they are on the outside, and two side surfaces close to the side surface, and another side surface formed by arranging one or more prism surfaces with an apex angle of π / 2 in the height direction. The second image forming unit is formed by arranging two second columnar transparent bodies having the above, or a columnar transparent body in which the two are integrated, in an array so as to face the prism surface.

Furthermore, a third invention of the present application is an imaging element devised to solve the above-mentioned first problem and also the second problem, wherein one of the convex lens arrays is It is characterized by a lens array having a plurality of rows.

[0011]

In the image forming device using the lens array, it is necessary for each constituent unit to form a continuous line image in which an erect image is formed. In the present invention, it is possible to make the image erect by using the reversal action of the reflecting surface, reduce the load on the lens, and suppress the aberration. Further, in the image forming element according to the third aspect of the present invention, by using a plurality of rows of lens arrays on either the image side or the object side, the image forming action in which the subject and the image correspond one-to-many or many-to-one Can be realized.

[0012]

The present invention will be described in detail below with reference to the drawings.
FIG. 1 is a perspective view showing an example of an image forming unit in an embodiment of an image forming element according to the first invention of the present application, and FIG. 2A is a plan view of the yz plane of the image forming unit of FIG. b) is a plan view of the xz plane. Reference numerals 1 and 2 in these drawings denote columnar transparent bodies in which convex lenses are formed on one side surface, and the optical axes of these convex lenses coincide with each other and are parallel to the z-axis. In addition, the columnar transparent body 3 has a triangular prism shape whose bottom surface is an isosceles triangle,
It has a reflection surface 4 having a reflection coating (aluminum plating or the like) on the side surface (parallel to the yz plane) including the bottom. Note that the convex lenses formed in 1 and 2 have the same focal length, and the object plane 6 and the image plane 7 are at positions away from the respective lenses by the focal length. Further, points O, O are the intersections of the optical axis with the object plane 6 and the image plane 7, and points x ₁ and y ₁ , -y ₁ are x from the points O, O on the object plane 6 and the image plane 7, respectively. A point having a distance x _{1 in} the direction and a point having a distance ± y _{1 in} the y direction.

First, the image forming action in the yz plane of the image forming unit shown in FIG. 1 will be described with reference to FIG. The light emitted from the point O or y ₁ on the object plane 6 is converted into parallel light by the convex lens surface of the columnar transparent body 1, propagates through the image forming unit, and reaches the convex lens surface of the columnar transparent body 2. In this process, the light ray is reflected on three planes, but the final traveling direction is the same as that before the reflection, and the convex lens surface of 2 causes the image plane 7
It is focused on one point O or -y ₁ . Y-coordinate (y _1, -y ₁₎ of the focusing position at this time is in the relation of the inverted image.

Next, the image forming action in the xz plane of the image forming unit shown in FIG. 1 will be described with reference to FIG. Similarly to the above, the light emitted from the point O or x ₁ on the object plane 6 is converted into parallel light by the convex lens surface of the columnar transparent body 1 and propagates through the imaging unit to form the convex lens of the columnar transparent body 2. Although reaching the surface, the side surface of the columnar transparent body 1, the reflecting surface 4, the columnar transparent body 2
And the direction of travel of the ray changes by being reflected three times in total, and the sign of the angle formed with the z axis is reversed. Therefore, the x-coordinate (x ₁ ) of the focus position on the image plane 7 focused by the convex lens surface 2 has an erect image relationship. It can be considered that this is because the inverted image projected by the two convex lenses is inverted three times by three reflections, and as a result, an upright image is obtained.

FIG. 4 is an exploded view of the imaging unit of FIG. This unit has a simple structure consisting of two kinds of four parts, and it is only necessary to assemble these parts so that they are in close contact with each other, and no troublesome axis alignment is required. Here, the columnar transparent body 3 is provided with light-shielding portions 5 and 8 in addition to the reflecting surface 4, the meaning of which will be described with reference to FIGS. 3 and 5. Figure 3
Of the light rays incident on the columnar transparent body 1, the light ray 13 whose incident angle on the side surface is smaller than the critical angle θ _c (= sin ⁻¹ (1 / n): n is the refractive index of the columnar transparent body) is incident on the side surface. As described above, the light rays that pass through the light beam deviate from the optical path of the light rays that form the image, and thus may become harmful stray light. Therefore, the light beam 12 that contributes to image formation does not pass through A-B, A-C, and D-E.
The light blocking portions 5 and 8 are intended to block stray light by blocking light between DF and DF. FIG. 5 is an expanded view of a mirror image reflected on the reflecting surface in order to explain the optical path of FIG. 3 in an easy-to-understand manner. Here, the paths of the rays that contribute to image formation are
Since it is limited between the apex angle of the columnar transparent bodies 1 and 2 and the two single-dotted chain lines connecting the ends of the convex lenses, it deviates from here.
Even if light is blocked between -B, between A-C, between D-E, and between D-F,
It does not impair the brightness of the image. On the contrary, most of the harmful light described above is blocked by the light blocking portions 5 and 8, and it is possible to prevent the contrast of the image from being lowered.

As can be seen from FIG. 5, Δ of the columnar transparent body 3
The part having ABC and ΔDEF as the base is not required, and a plan view of the part without this is shown in FIG. This is also an example of the imaging unit according to the first invention of the present application. In this example, a side surface 9 is provided to cut off harmful light.
9 may be painted black to form a light-shielding surface. FIG. 7 is an xz plan view showing another example of the image forming unit in the image forming element according to the first aspect of the present invention. In FIG. 7A, the columnar transparent bodies 3 on both sides are integrated, a distance is provided between the columnar transparent bodies 1 and 2, and the position of the reflecting surface 4 is also shifted in the −x direction and the x direction. In the examples shown in FIGS. 1, 6, and 7 (a) above, the vertical angles of the columnar transparent bodies 1 and 2 are 60 °, but this is not a necessary condition. FIG. 7 (b) shows an example in which the apex angle θ is larger than 60 °, and FIG. 7 (c) shows an example in which the apex angle θ is smaller than 60 °. If θ is large, z of the imaging unit
Although the width in the direction is narrowed and the conjugate length is slightly shortened, the light ray cannot be effectively used unless the reflecting surface 4 is moved away, and as a result, the imaging unit has a wide width in the x direction. Since it is necessary to widen the unit interval when forming an array by this amount, there is a possibility that brightness and uniformity may be degraded. On the contrary, if θ is small, the width in the z direction is widened and the conjugate length is extended. Therefore, it is not preferable to make θ too large or small, and the preferable range is about 50 ° to 70 °, although it depends on the refractive index of the columnar transparent body and the focal length of the convex lens.

As such, it can be seen that the imaging unit of FIG. 1 projects a unity-magnification image with the y coordinate reversed and the x coordinate preserved. Therefore, by arranging the units in the x-axis direction as shown in FIG. 8, an inverted image on a continuous line can be obtained, which is the function of the image forming element according to claim 1 of the present invention. In the case of forming an array in this way, the columnar transparent bodies 1 and 2 integrally molded in an array can be used, and the assembly can be further simplified.

The inversion of the image in the y direction does not cause any inconvenience in applications such as a linear image sensor, a liquid crystal printer, an LED printer. On the other hand, a mirror can be used for applications such as a copying machine in which an inverted image is inconvenient, and the inverted image can be inverted to form an erect image. In the embodiment shown in FIG. 8, the brightness, uniformity, and resolution of the projected image are apex angle θ, the diameter and focal length of the convex lens, the columnar transparent body 1,
2 and the position of the reflecting surface 4, etc. Therefore, the degree of freedom in designing this device is high, and it is understood that the image forming element has a wide variation.

In the image forming unit of FIG. 1, the convex lens is formed on one side surface of the columnar transparent body, but the convex lenses 1a and 2 are formed.
The a and the triangular prism-shaped transparent bodies 1b and 2b may be separately molded and arranged as shown in FIG. Next, an image forming element according to the second invention of the present application will be described with reference to the drawings. FIG. 9 shows the second application of the present application.
10A is a perspective view showing an example of an image forming unit in an embodiment of the image forming element according to the invention of FIG. 10, FIG. 10A is a plan view of a yz plane of the image forming unit of FIG. 9, and FIG. FIG. In the figure, the same components as those of the imaging unit in FIG. 1 are designated by the same reference numerals. This imaging unit
The reflecting surface 4 of the image forming unit of FIG. 1 is replaced with an array 10 of rectangular prisms, and the image forming action in the xz plane is exactly the same as that of the image forming unit of FIG. 1 as shown in FIG. However, in the yz plane, the traveling direction of the light beam changes due to reflection from the rectangular prism as shown in FIG. 10B, and the sign of the angle formed with the z axis is reversed. Therefore, the y coordinate (y ₁ ) of the focus position on the image plane 7 focused by the convex lens surface of 2 has an erect image relationship, and the projected image is an erect equal-magnification image in which both the x coordinate and the y coordinate are preserved. become. Therefore, the present image forming unit has a feature that it can be used as it is for applications such as a copying machine.

In the present image forming unit, since it is possible to use the rectangular prism array 10 as a total reflection prism unless there is a particular need to widen the field of view in the y direction, there is an advantage that a reflection coat is unnecessary. FIG. 11 is a perspective view showing an embodiment of an imaging element according to the second invention of the present application in which the present imaging unit is arranged in an array. This embodiment is an embodiment of the imaging element according to the first invention of the present invention of FIG. Unlike the example, the feature is that an upright image can be projected. Also here, as the columnar transparent bodies 1 and 2, those integrally molded in an array form are used.

In the image forming unit shown in FIG. 9, a columnar transparent body 1 is formed on a side surface of which a row 10 of five right-angled prisms arranged vertically is formed.
Although 1 is used, by arranging a large number of prisms with such a narrow width, it is possible to reduce the space opened between the image forming units when forming an array as shown in FIG. 11, and to improve efficiency. it can. Of course, even a single right-angle prism has no functional problem, and FIG. 15 shows that special case.

Next, an image forming element according to the third aspect of the present invention will be described with reference to the drawings. FIG. 12 is a perspective view showing an image forming unit in an embodiment of the image forming element according to the third invention of the present application. The image forming unit can project two images, which are displaced in the y direction, on the image plane 7 side by using the columnar transparent body 14 in which two convex lenses are vertically arranged on the exit plane. FIG. 13 is a perspective view showing an embodiment of an image forming element according to the third invention of the present application in which the present image forming unit is arranged in an array, and an object and an image correspond one-to-two. As can be easily understood, it is possible to further increase the number of images by forming the convex lenses on the image plane 7 side in three or more rows, or by forming a large number of rows of convex lenses on the object plane 6 side to form an image forming element. Is also possible. Another embodiment can be obtained by replacing the reflecting surface 4 with an array of rectangular prisms as in the image forming element according to the second aspect of the present invention.

An example in which the above-mentioned image forming element is actually manufactured will be described below. First, the columnar transparent bodies 1, 2 and 3 shown in FIG. 1 are manufactured by using a transparent resin having a refractive index of 1.53.
(However, the columnar transparent bodies 1 and 2 are not integrally molded in an array, but the image forming units are simply arranged.). The apex angle θ of the columnar transparent bodies 1 and 2 is 60 °, the width of the two side surfaces sandwiching the transparent body is 6 mm, and the formed convex lens is a spherical lens of 6 mm × 6 mm square with a radius of curvature of 8 mm. The reflecting surface 4 was formed by aluminum vapor deposition, and a black paint was applied to form the light shielding portions 5 and 8. As a result, it was confirmed that a clear inverted equal-magnification image can be obtained by this imaging element.

Next, the columnar transparent body 3 of this image forming element was replaced with a columnar transparent body having a rectangular prism array, and an image forming element according to the second invention of the present application was assembled. However, the pitch of the rectangular prisms 10 is 0.5 mm, and the number of arrays is different from that of the embodiment shown in FIG. A clear erect image of the same size was obtained with this imaging device. In addition, the first columnar transparent body 2 of the image forming element,
An image forming element according to the third invention of the present application was prepared by replacing the columnar transparent body 14 in which two spherical lenses having a radius of curvature of 8 mm and 3 mm × 6 mm square were formed. As a result, it was confirmed that two clear 1 × inverted images were obtained by this imaging device.

[0025]

As described above, the image forming device according to the present invention is arranged on a line by arranging a pair of convex lenses and image forming units for forming an inverted or erecting equal-magnification image by the reflection action of the prism surfaces in an array. The image forming element of the present invention is easy to manufacture, and since the integration of the refraction angles associated with the image formation is small, it is possible to obtain an image with little chromatic aberration.

[Brief description of drawings]

FIG. 1 is a perspective view showing an example of an image forming unit in an image forming element according to the first invention of the present application.

FIG. 2 is a plan view of the imaging unit of FIG.

FIG. 3 is an explanatory diagram for explaining the operation of the imaging unit in FIG.

FIG. 4 is an exploded perspective view of the imaging unit of FIG.

5A and 5B are explanatory diagrams for explaining the operation of the image forming unit in FIG.

FIG. 6 is a plan view showing another example of the image forming unit in the image forming element according to the first invention of the present application.

FIG. 7 is a plan view showing still another example of the imaging unit in the imaging element according to the first invention of the present application.

8 is a perspective view showing an embodiment of an image forming element according to the first invention of the present application, which is an array of the image forming units of FIG. 1. FIG.

FIG. 9 is a perspective view showing an example of an image forming unit in the image forming element according to the second invention of the present application.

FIG. 10 is a plan view of the imaging unit of FIG.

FIG. 11 is a perspective view showing an embodiment of an imaging element according to the second invention of the present application.

FIG. 12 is a perspective view showing an example of an image forming unit in an image forming element according to the third invention of the present application.

FIG. 13 is a perspective view showing an embodiment of an imaging element according to the third invention of the present application.

FIG. 14 is a perspective view showing another example of the imaging unit in the imaging element according to the first invention of the present application.

FIG. 15 is a perspective view showing another example of the imaging unit in the imaging element according to the second invention of the present application.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Columnar transparent body in which a convex lens is formed 2 ... Columnar transparent body in which a convex lens is formed 3 ... Columnar transparent body having a reflective surface 4 ... Reflective surface 5 ... Shading portion 6 ... Object surface 7 ... Image surface 8, 9 ... Shading portion 10 ... right-angle prism array 11 ... columnar transparent body having prism array 14 ... columnar transparent body having two convex lenses 15 ... right-angled prism surface 16 ... columnar transparent body having right-angled prism surface 17, 18 ... light-shielding portion 1a, 2a ... convex lens 1b, 2b ... Triangular prism transparent body

Claims (3)

[Claims] 1. A first columnar transparent body having two side surfaces intersecting at an acute angle, wherein two convex side lenses are provided on the other side surface with respect to the acute angle, and two are arranged symmetrically so that the convex lens is on the outside. And a side surface adjacent to each side surface of the two first columnar transparent bodies forming an obtuse angle which is a supplementary angle to the acute angle, and a side surface for the obtuse angle and on which a reflecting surface is formed. An image forming unit in which two second columnar transparent bodies each having the above or a columnar transparent body in which two are integrally formed are combined and joined and arranged in an array so as to face the reflection surface. Child. 2. A first columnar transparent body having two side surfaces intersecting at an acute angle, wherein two convex lenses are provided on the other side surface with respect to the acute angle, and two are arranged symmetrically so that the convex lens is on the outside. And a side surface adjacent to each side surface of the two first columnar transparent bodies forming an obtuse angle which is a supplementary angle to the acute angle, and a prism having an apex angle of π / 2 with respect to the obtuse angle. An image forming unit in which two second columnar transparent bodies having one or more side surfaces juxtaposed in the height direction or columnar transparent bodies in which the two are integrated are combined and disposed. An imaging element arranged in an array so as to face the prism surface. 3. The convex lens disposed on either the object plane or the image plane side is a plurality of convex lenses arranged in parallel in a direction orthogonal to the array direction of the array. Item 2. The imaging element according to item 2.