JPH0727995A - 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 each having two sides crossing each other at a steep angle and convex lenses arranged on the other sides to this steep angle are symmetrically arranged in such a manner that the convex lenses exist respectively on the outer sides. One or more orthogonal reflection surface pairs are arranged 4 to face the respective regions held by the sides of these two columnar transparent bodies. The imaging units constituted in the manner described above are arranged in an array form to constitute this imaging element. The columnar transparent bodies of the imaging units are formed as the columnar transparent bodies continuous in an array direction and are constituted by combining and joining the columnar transparent bodies in which the continuous arrangement in the array direction of the orthogonal reflection pairs are formed.

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.

Furthermore, 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 there is a problem that unevenness in brightness occurs if the roof prism (or roof mirror) and the lens are not aligned correctly.

The first problem to be solved by the present invention is
It is to obtain an imaging element that does not require particularly difficult know-how, is easy to manufacture, 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 as in the former case, and there is no choice but to use a plurality of line image sensors. When connecting a plurality of line image sensors 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 a gap.
This causes a deviation of the reading line,
It is necessary to correct this in a circuit.

Further, even in an LED printer or a liquid crystal printer, it is not technically easy to make an LED array or a 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. A second problem to be solved by the present invention is to obtain an image-forming element in which a subject and an image correspond one-to-many or many-to-one. In a contact image sensor, this makes it possible to connect the images on one line to two or more lines and read the image of the same line with the line image sensors arranged in a staggered pattern on these lines. , Line correction becomes unnecessary. Further, in an LED printer or a liquid crystal printer, a complete one-line image can be created by connecting the images of short LED arrays or liquid crystal shutters arranged in a zigzag pattern on a plurality of lines on the same line. It is possible to use the LED array and the liquid crystal shutter having a length that is easy to manufacture.

[0008]

The first and second inventions of the present application have been devised to solve the above first problem.
The imaging element according to the first invention of the present application is one in which a columnar transparent body having two side surfaces intersecting at an acute angle, in which a convex lens is formed or arranged on the other side surface with respect to the acute angle, is arranged so that the convex lens is on the outside. The imaging units, which are symmetrically placed and have one or more pairs of reflecting surfaces forming a valley with an apex angle of π / 2 facing the two side surfaces sandwiching these acute angles, are arranged in an array and arranged. The direction is perpendicular to the optical axis of the convex lens and the valley line of the pair of reflecting surfaces.

The imaging element according to the second invention of the present application is
A columnar transparent body having two side faces intersecting at an acute angle is provided or formed with an array of convex lenses arranged in the height direction of the columnar transparent body on the other side face with respect to the acute angle. Symmetrically, and has two side surfaces forming an obtuse angle equal to the supplementary angle of the acute angle, and a prism surface having an apex angle of π / 2 is formed on the side surface with respect to the obtuse angle at a period equal to or shorter than the period of the convex lens array. Two columnar transparent bodies formed side by side in the vertical direction are arranged so that the two side surfaces that sandwich the acute angle of the former columnar transparent body and the two side surfaces that form the obtuse angle of the latter are parallel and close to each other.

Further, an image forming element according to the third invention of the present application is an image forming element devised to solve the above-mentioned first problem and further solves the second problem. One of them is a lens array having a plurality of columns.

[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. According to the imaging element of the present invention, it becomes possible to erect an image by using the reversal action of the orthogonal reflecting surfaces to 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, an image forming action in which the subject and the image correspond one-to-many or many-to-one Will 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.
Is a plan view of the xz plane of the image forming unit of FIG. 1, and FIG. 2B is a plan view of the yz plane thereof. Reference numerals 1 and 2 in these drawings denote columnar transparent bodies made of triangular prisms having convex lenses formed on one side surface, and the optical axes of these convex lenses coincide with each other and are parallel to the z axis. The side plate members 3 placed on the upper and lower sides have an array 4 of reflecting surface pairs composed of two reflecting surfaces orthogonal to each other, and the two reflecting surfaces of each reflecting surface pair are parallel to the z axis and ± 45 ° with respect to the y axis. Are arranged in the x-axis direction. In addition, transparent bodies 1 and 2
The focal lengths of the convex lenses formed on the
The image plane 6 is at a position separated from each convex lens by the focal length. Also, x ₁ , x ₁ ′, and y ₁ , y ₁ ′
On the object plane 5 and the image plane 6, respectively, are origins O,
A point on the x-axis and y-axis equidistant from O '.

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. In the figure, the areas indicated by M1 and M2 indicate mirror images reflected on the side surfaces 7 and 8 of the columnar transparent bodies 1 and 2, respectively. Light emitted from the origin O intersecting the optical axis on the object plane 5 and entering the right half (left half in the mirror image) of the convex lens surface of the columnar transparent body 1 becomes parallel light by the action of the convex lens, and Side surface 7, orthogonal reflection surface pair array 4,
The light is reflected by the side surface 8 of the columnar transparent body 2, reaches the convex lens surface of the columnar transparent body 2, and is condensed at the origin O ′ on the image plane 6. The image obtained by projecting only the convex lens is an inverted image, but the image is inverted each time it is reflected and the number of reflections is three, so the image finally obtained is an erect image.

Next, the image forming action in the xz plane of the image forming unit of FIG. 1 will be described with reference to FIG. Mirror image M for simplicity
1 and M2, the x-coordinates are not inverted by the side surfaces 7 and 8 of the columnar transparent bodies 1 and 2 as is apparent from FIG. 3, so it is sufficient to explain the mirror image forming action. is there. The columnar transparent body 1 emanating from the points O and x ₁ on the object plane 5
The light entering the convex lens surface of becomes parallel light by the action of the convex lens and is incident on one reflecting surface pair of the reflecting surface pair array 4,
Due to the action of the reflecting surfaces that intersect at right angles, the light is reflected in the direction parallel to and opposite to the incident light. This light ray is condensed by the convex lens surface of the columnar transparent body 2 at the same x coordinate as the light emitting points O and x ₁ on the object plane 5 on the image plane 6, that is, at points O ′ and x ₁ ′. Therefore, the obtained image is an erect image also in the x direction.

That is, by inverting the image by mirror reflection three times in the y-direction and inverting the image on the reflecting surface (the roof surface) orthogonal to the x-direction, the images are erected, respectively.
The image forming unit of can project an erecting equal-magnification image. Viewing angle φ in the y direction of the imaging unit of FIG.
As shown in FIG. 5, the angle 2θ formed by the two side surfaces of the columnar transparent bodies 1 and 2 and the critical angle θ _c (where θ _c = sin ⁻¹ (1
/ N): n is determined by the refractive index of the columnar transparent body. Of the incident light, the light incident on the side surface at an angle of θ _c or less passes through the side surface 7 or 8 as shown by the dotted line 9, so that an erect image cannot be formed as described above. Therefore, an image outside the range of the viewing angle φ represented by the following formula (1) from the center of the lens is not projected, and light in this range is harmful, so do not use it or use an optical diaphragm such as a slit. It is preferable to use and cut. As can be seen from the following expression (1), when θ, that is, the apex angle 2θ is increased, the field of view is narrowed, which is not preferable, and 2θ is preferably 70 ° or less.

[0016]

[Equation 1]

From the viewpoint of downsizing of the device, the most preferable value of the apex angle 2θ is 60 °. At this time, the columnar transparent body is one in which a convex lens is formed on one side surface of a regular triangular prism, and FIGS. 1 to 5 are drawings for this numerical example. A large apex angle 2θ has the effect of slightly shortening the conjugation length, as shown in FIG. 7A, but the light rays cannot be effectively used unless the reflecting surface pair array 4 is moved away. Becomes an imaging element having a wide width in the y direction. Conversely, as shown in FIG. 7B, the apex angle 2θ is 60 °.
A smaller value has the effect of widening the visual field in the y direction, but it is not preferable because the width in the z direction widens and the conjugate length also increases. The preferable range of the apex angle 2θ is about 50 ° to 70 °, although it varies depending on the refractive index of the columnar transparent body.

FIG. 6 shows an embodiment of the image forming device according to the first invention of the present application, in which the image forming unit of FIG. 1 is arranged in the height direction of the columnar transparent body perpendicular to the optical axis as shown. Is shown. Here, it is preferable that the light-shielding plate 10 is sandwiched between the image forming units so that the light rays of the adjacent units are not mixed. 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 lens and the columnar transparent body may be separately molded and arranged as shown in FIG. 8A. . The orthogonal reflecting surface array 4 used in the apparatus shown in FIGS. 1 to 8A is formed by forming a plurality of right-angled grooves on an opaque plate 3 and coating a metal such as aluminum.
As a matter of course, this surface must have a high surface accuracy. Further, as a special example, the one as shown in FIG. 8B using a single pair of reflecting surfaces which are orthogonal to each other can also be used as the image forming unit of the present invention.

Next, the second invention of the present application will be described with reference to the drawings. FIG. 9 is a perspective view showing an image forming unit in an embodiment of the image forming element according to the second invention of the present application, and FIG.
Is a plan view of the xz plane of the imaging unit shown in FIG. 9, and FIG.
Is a plan view of the yz plane. The operation of this image forming unit is basically the same as that of the image forming unit of FIG. 1, and the same reference numerals are given to the same elements, but the reflecting surface pair array 4 of FIG. , 11 in that they are replaced by an array 12 of right-angle prisms formed on the side surfaces. Therefore, the following merits which are not provided in the image forming unit of FIG. 1 are added. For the sake of simplicity, the following discussion will be concerned with the imaging action of the points on the horizon, which is the most important for the imaging element, including the point on the object plane 5 which intersects the optical axis of the lens.

First of all, since the prism array 12 can utilize total reflection, a reflection coat is not always necessary.
As a matter of course, it is preferable to omit the reflection coat because the manufacturing cost is reduced. For example, the apex angle 2θ of the columnar transparent bodies 1 and 2 =
At 60 °, the incident light is 30 ° on the prism array in the zy plane.
Is incident at an incident angle of. Such obliquely incident light rays have a wide angle range in which they are totally reflected. Specifically, the unit of FIG.
An aperture angle of about ± 15 ° is shown in the x direction at around 1.5, and the unit width and working distance are set so that the range of the image reflected at this aperture angle partially overlaps the adjacent unit. By doing so, a connected image can be completed even if the reflective coat is omitted.

By thus limiting the aperture angle of each unit, it becomes possible to omit the light shielding plate 10 shown in FIG. 6 which is required when the image forming unit shown in FIG. 1 is formed into an array. FIG. 12 is a perspective view showing an embodiment of an imaging element according to the second invention of the present application, and FIG. 11 is an exploded perspective view showing four parts of two kinds constituting the same. Here, the suffix "a" is added to each component in the sense of an array component to distinguish it from the unit of FIG. Here, the columnar transparent body 1
a, 2a and prismatic columnar transparent bodies 1 located above and below
1a and 11a are the same respectively. When viewed two-dimensionally, the orthogonal reflecting surface pair has a function of reflecting light rays in the incident direction, and particularly in the case of a narrow reflecting surface pair, this is the position at the same distance as the object as seen from the reflecting surface pair. It can be regarded as an image-forming action that creates a 1 × image. Due to this action, most of the light incident on one convex lens on the columnar transparent body 1a in FIG. 12 reaches the corresponding convex lens of the columnar transparent body 2a and contributes to image formation. As can be seen from FIG. Is not parallel to the pair of reflecting surfaces, the distances of the convex lens on the incident side and the convex lens on the emitting side from the reflecting surface pair (prism 12) partially match, and therefore, there is a finite distance to the reflecting surface pair in the x-axis direction. For obliquely incident light that enters at an angle, the image of the convex lens on the incident side protrudes from the convex lens on the outgoing side. The size is (Rtan θtan α) /
2 (where R is the width of the convex lens in the y direction and α is the maximum oblique incident angle), but in the prism, due to the above-mentioned limitation of α due to total reflection (about ± 10 ° around n = 1.5). Since the value of this equation is as small as about 0.05R, as shown in FIGS. 11 and 12, by providing the light shielding portion 14 of about 1/10 of the lens width between the convex lenses, it leaks from the adjacent unit. The light can be removed, and the light shielding plate 10 is unnecessary.

Since it is not necessary to divide the units in this way, it is possible to form an imaging element with four parts of two types, and since these are assembled in contact with each other, manufacturing is extremely easy. The cost has come to be reduced. This is the second advantage of the second invention of the present application. In addition, since the imaging action of the above-mentioned orthogonal reflecting surface pair is accompanied by a maximum deviation of the width of the reflecting surface pair,
In consideration of this, the width of the light shielding portion 14 is (Rtan θt
It is preferably equal to anα) / 2 plus the width of the prism. The wider the light-shielding portion 14, the lower the light utilization factor and a darker imaging element. Therefore, in this sense, the width of the prism should be sufficiently smaller than the width of the lens, preferably 1/5 to 1 It is better to be / 10 or less.

Further, in FIG. 11, the light shielding portion 13 (black coating) is provided on the prismatic columnar transparent body 11a, so that the stray light component as shown by the dotted line 9 in FIG.
It is blocked by and is prevented from emitting to the image side. As a result, the image-forming element according to the present invention becomes easier to use. For example, it is possible to arrange the image-forming elements of FIG. 12 vertically to form a planar image-forming element that projects a large-area 1 × image. This is the third advantage of the second invention of the present application.

FIGS. 13 and 14 show Z of the image forming unit in another embodiment of the image forming element according to the second invention of the present application.
It is a Y top view. In the embodiment of FIG. 13, the apex angle 2θ of the above-mentioned columnar transparent bodies 1 and 2 is set to be smaller than 60 °, a gap is formed between them, and the two columnar transparent bodies 11 are integrated to further reduce the number of parts. It reduces the number and increases the ease of assembly. In the embodiment shown in FIG. 14, the columnar transparent body 11 'is made slim by removing unnecessary portions of the columnar transparent body 11.
To reduce the weight of the imaging element.

FIG. 15 shows a practical form of the image forming element according to the second invention of the present application in which the side plate 15 is added to the image forming element of FIG. The side plate 15 is a black member having a light-shielding function, and it is preferable to use FRP or the like to have strength and dimensional stability. Next, an image forming element according to the third invention of the present application will be described with reference to the drawings. 16 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.
7 is a plan view of the zy plane of the imaging unit of FIG. The image forming unit projects two images, which are displaced in the y direction, on the image side by using a columnar transparent body 32 in which two convex lenses are vertically arranged on the exit surface. FIG. 18 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 image by providing three or more rows of convex lenses on the image plane side, or to arrange a large number of convex lenses on the object plane side to form an image-forming element for synthesizing images. It is possible.

Using a transparent resin having a refractive index of 1.53, FIG.
The columnar transparent bodies 1a, 2a, and 11a were manufactured, and the imaging element of FIG. 12 was assembled. Vertical angle 2θ of columnar transparent bodies 1a, 2a
Is 60 °, the width of the two side faces sandwiching this is 6 mm, the convex lens formed is a spherical lens of 6 mm × 5 mm square with a radius of curvature of 8 mm, and a light-shielding portion 14 having a width of 1 mm is provided between the lenses by black coating. The pitch of the prism rows 12 is 0.5.
In mm, the length of each member is 60 mm (10 convex lenses). As a result, it was confirmed that a clear erect equal-magnification image can be obtained by this imaging element.

Further, the columnar transparent body 32a of FIG. 18 was manufactured using the same transparent resin, and was replaced with the above-mentioned columnar transparent body 2a to prepare the image forming element of FIG. Columnar transparent body 32
The convex lens formed in a is a 3 mm × 5 mm square spherical lens with a radius of curvature of 8 mm, and is formed in two rows as shown in FIG. As a result, it was confirmed that two clear erect equal-magnification images can be obtained by this imaging element.

[0028]

As described above, the image forming device according to the present invention is arranged on a line by arranging image forming units forming an erecting equal-magnification image in an array by the action of a pair of reflecting surfaces orthogonal to a pair of convex lenses. 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 explanatory diagram for explaining the operation of the imaging unit in FIG.

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

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

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

FIG. 8 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. 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 an exploded perspective view showing the configuration of an embodiment of the imaging element according to the second invention of the present application.

FIG. 12 is a perspective view showing an embodiment of an imaging element according to the second invention of the present application.

FIG. 13 is a plan view of another example of the imaging unit in the imaging element according to the second invention of the present application.

FIG. 14 is a plan view of another example of the imaging unit in the imaging element according to the second invention of the present application.

FIG. 15 is a perspective view showing a practical form of an imaging element according to the second invention of the present application.

FIG. 16 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.

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

FIG. 18 is a perspective view showing an embodiment of an imaging element according to the third invention of the present application.

[Explanation of symbols]

 1, 2 ... Columnar transparent body formed with convex lenses 3 ... Side plate member having a pair of reflective surface pairs 4 ... Orthogonal reflective surface pair array 5 ... Object surface 6 ... Image plane 7 ... Side surface 1 of columnar transparent body 8 ... Columnar transparent Two side surfaces of the body 10 ... Shading plate 11 ... Columnar transparent body having prism rows 12 ... Right angle prism array 13, 14 ... Shading part (black coating) 15 ... Side plates 21, 23 ... Convex lenses 22, 24 ... Columnar transparent body 32 ... Columnar transparent body with two convex lenses

Claims (3)

[Claims] 1. Two columnar transparent bodies having two side surfaces intersecting at an acute angle and a convex lens disposed on the other side surface with respect to the acute angle, each of the convex lenses being on the outer side, and the optical axis of each convex lens. Are arranged symmetrically so that they coincide with each other, facing each obtuse angle sandwiched by the side surfaces of the two columnar transparent bodies,
An image forming unit in which one or more pairs of reflecting surfaces whose apex angle forms a valley of π / 2 and whose valley line is parallel to the optical axis of the convex lens are arranged in the height direction of the columnar transparent body, An image forming element having an array in the array direction of the pair of reflecting surfaces. 2. Two side surfaces, which intersect at an acute angle, and a first columnar transparent body having an array of convex lenses arranged side by side in the height direction of the columnar transparent body on the other side surface with respect to the acute angle,
The convex lens array is arranged symmetrically so as to be on the outer side, and has two side surfaces forming an obtuse angle equal to the supplementary angle of the acute angle, and a prism surface having an apex angle of π / 2 is provided on the side surface with respect to the obtuse angle. 2 of the second columnar transparent bodies formed in a row in the height direction with a period equal to or less than the two periods, the two side faces sandwiching the acute angle of the first columnar transparent body and the obtuse angle of the second columnar transparent body. An image forming element, which is disposed in close proximity to the two side faces of the so as to face each other in parallel. 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 perpendicular to the array direction. The imaging element according to claim 2.