JPH06130325A - Surface division projecting element - Google Patents

Abstract

PURPOSE:To obtain the surface division projecting element which is a projecting element formed by combining a tab prism assembly and a convex lens array together and has a reducing and enlarging function. CONSTITUTION:Two convex lenses 1 and 2 which are different in focal distance are arranged on the light incidence/projection surface of an array of plural tab prism assemblies each formed by joining two section symmetrical trapezoidal tab prisms 3 with their light reflecting surfaces out so that the ratio of the array interval D of convex lenses 1 arranged on the light incidence side and the array interval (d) of convex lenses 2 arranged on the light projection side is equal to the ratio of the focal distance F of the convex lenses 1 arrayed on the light incidence side and the focal distance (f) of the convex lenses 2 arrayed on the light projection side.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plane-division projection element having an enlargement / reduction function used in a slit exposure type analog copying machine.

[0002]

2. Description of the Related Art A slit exposure type analog copying machine uses a projection element for projecting a copying body on a reading line onto a photosensitive body. Especially, in a small copying machine, a gradient index rod lens is used. A plane-division type projection element represented by a rod lens array which is an array is conveniently used. Such a surface-splitting element is a compact optical system and has the advantage that it is easy to assemble and adjust the focal length, but on the other hand, it can only form an image of equal magnification, so it is necessary to enlarge or reduce the copy. There is a drawback that it does not serve as a split projection element.

[0003]

As described above, it is extremely difficult to give the enlargement / reduction function to the plane-division projection element such as the rod lens array, and the development of the plane-division projection element having the enlargement / reduction function has been developed. I'm waiting.

[0004]

Therefore, the present inventor has completed the present invention as a result of an examination for the purpose of developing a surface division element having an image enlarging / reducing function. In order to do so, two tab prisms having symmetrical trapezoidal cross sections are symmetrically assembled so that their light reflecting surfaces are on the outside, and a plurality of tab prism assemblies are linearly arranged so that their light reflecting surfaces face each other. Arrayed and linearly arranged tab prism assemblies with different focal lengths on the light input and output end faces 2
An array interval D of the convex lenses disposed on the light incident end side and an array interval d of the convex lenses disposed on the light emission end side of the kind of convex lens.
And a convex lens disposed on the light incident end side and a focal length of the convex lens disposed on the light emitting end side are equal to each other. It is in.

FIG. 5 shows a cross section of a tab prism 3 having a symmetrical trapezoidal cross section used in the present invention. The light incident at an angle α with the axis of the tab prism is refracted to the light reflecting surface side of the tab prism, and the light reflected on the light reflecting surface is It emits at an angle α with the axis.

The angle formed by the hypotenuse and the bottom surface of the tab prism is θ, and this θ is preferably as large as possible. If this angle θ is too small, the light emitted from the object surface will not be reflected by the light reflecting surface of the tab prism, and stray light will be emitted directly from the emission surface, and the contrast of the obtained image will be reduced. From such a viewpoint, it is preferable that the angle θ satisfies the condition of θ ≦ 90 ° −sin ⁻¹ (1 / n) (where n is the refractive index of the material forming the tab prism).

Further, the ratio a / b of the length b in the width direction of the tab prism to the length a of the base in the axial direction satisfies [Equation 1], so that the vicinity of the optical axis where the aberration of the lens is small is the most. It is preferable in terms of brightening, but the overall image brightness is a
It becomes brighter when / b is slightly smaller than [Equation 1]. Also,
Image uniformity is sensitive to a / b, and the optimum value varies depending on the focal length of the lens used and the arrangement interval of the tab prism assembly, so experiments or computer simulations should be used to It is better to make it slightly smaller than the value of 1].

[Equation 1]

FIG. 4 is a perspective view of a tab prism assembly used in the present invention. In FIG. 4, reference numeral 8 is a joint surface formed by a black adhesive for joining two tab prisms.

In a surface-division type projection element using a lens array, the image-forming element itself constituting the lens array produces an erect image.
Connecting in any direction is a necessary condition for using the line image forming element as a plane division projection element, but the requirement for forming an erect image may be satisfied only in the direction in which the image forming elements are arranged in a line, Even an inverted image can be sufficiently used in the direction perpendicular to the line direction.

FIG. 1 is a plan view showing an xz plane and an image forming mechanism of the surface-division projection element of the present invention, FIG. 2 is a plan view of the yz plane and an image forming mechanism, and FIG. 3 is shown. It is a perspective view of a reduction type image reading sensor using the plane division projection element of the present invention. Among the reference numerals in these figures, 1 is a convex lens provided at the light incident end of the tab prism assembly, 2 is a convex lens provided at the light emitting end of the tab prism assembly, 3 is a tab prism, 4 is a light blocking member, and 5 is a light shielding member. The object plane, 6 shows the image formation. Object plane 5, image plane 6
Are at positions separated by the focal lengths from the respective convex lenses, and an inverted image is formed in the y direction as shown in FIG.
In the direction, the tab prism 3 serves to form an erect image as shown in FIG.

First, the bottom length is 20 mm, the bottom width is 5 mm, and the height is 10 m.
Two tab prisms made of polymethylmethacrylate with m and hypotenuse angle θ = 45 ° are joined with a black adhesive so that the top and bottom surfaces are aligned, and four tab prism assemblies are prepared. As convex lenses, three convex lenses (A) having a focal length F = 40 mm and four convex lenses (B) having a focal length f = 45 mm were prepared. As shown in FIG. 1, four tab prism assemblies were assembled by placing a light shielding member 4 having a thickness of 6.6 mm between the tab prism assemblies. On the upper surface of the array of the tab prism assembly, as shown in FIG.
10 mm × 2 of the convex lenses (A) so that they are centered on the optical axis
Cut it into a rectangle of 20mm, and the other 2 pieces are 10mm at the center of the optical axis.
Cut into 10mm, as shown in Fig. 1, convex lens on the incident side
(A) Axial distance D = 20 mm is arranged, and a convex lens
(B) was cut into a rectangle of 10 mm × 15 mm and arranged on the emitting side with an optical axis interval d = 15 mm to obtain a plane division projection element of the present invention.

Referring to FIG. 1, xz of the plane division projection element of the present invention.
The in-plane image forming mechanism will be described. First, convex lens (A)
The intersection of the optical axis of the single lens (A) included in the array element and the object plane 5 is set to 0, and the optical axis of the single lens (B) included in the element of the lens (B) array and the image plane 6 The intersection of is 0 '.
Light emitted from the distance apart points x ₁ of x ₁ from the point 0 on the object surface 5 enters the convex lens (A), the optical axis by the action of the convex lens (A) (z
It is converted into parallel light that forms an angle −tan ⁻¹ (x ₁ / F) with the axis) (where F is the focal length of the convex lens (A)). Then, by the action of the tab prism, this light is converted into parallel light that forms an angle tan ^-1 (x ₁ / F) with the optical axis, and the convex lens (B)
By the action of, the image is formed at a distance of x ₁ '= x ₁ × f / F from the point 0'on the image plane 6 (where f is the focal length of the convex lens (B)).

That is, the image on the image plane is the origin 0 on the image plane.
Is moved to the origin 0'of the image plane and is formed as a reduced image of f / F times. The distance between adjacent convex lenses is D (= 20 m on the object side).
m) whereas d (= 15 mm) on the image side, and d / D = f / F (3/4 times), the reduced image projected by the adjacent convex lens is displaced. Instead, it forms a continuous image as shown in FIG.

FIG. 2 is a view for explaining the image forming mechanism of the yz plane of the plane division projection element of the present invention. Since the convex lens (A) and the convex lens (B) are used in tandem, the magnification is an inverted image of f / F (3/4 times) (see Fig. 3).

That is, for each projection element, (a) position-angle conversion by the lens (A), (b) angle inversion in the xz plane by the tab prism, (c) angle by the convex lens (B)-
By position conversion, an inverted f / F magnified image is obtained only in the y direction, and the distance between these images is reduced by f / F (d / D) times.
As a whole, an inverted image of f / F times inverted is obtained. By inverting the object plane and the image plane, it is possible to form a magnified image of an inverted image of F / f times.

It can be seen that the reduction (enlargement) magnification of the plane division projection element of FIG. 1 is 3/4 (4/3). That is, this reduction ratio is f / F = d / D = 3/4. As described above, the reduction length of the projected image of the plane-division projection element of the present invention in which one set of the convex lens array and the array of the tab prism assembly are combined is limited by the pitch of the lens array on the projection side. Therefore, the larger the number of tab prism assemblies arranged in the convex lens array, the larger the limit of reduction magnification of the projection element. The size of the apparatus can be reduced by using a projection element that uses as many tab prism assemblies as possible. From this point of view, it is preferable for the apparatus that the reduction and enlargement ratios of the surface-division projection element of the present invention are in the range of 0.75 to 1.3 times.

FIG. 6 is a plan view of the xz plane of another example of the plane division projection element of the present invention. In this example, in order to improve the image forming brightness of the projection element, the same tab prism assembly arrangement as that used in FIG. 1 is eliminated, and a thin light shielding plate 7 is inserted in the convex lens arrays 9 and 10. As for the above, a simple convex lens array was not used, but a convex lens of a shape obtained by cutting out a part of a single lens while gradually changing the position was used. The convex lens 9 has a focal length F of 60 mm, and the convex lens 10 has a focal length f of 40 mm. The convex lens array 9 has a convex lens (A) with an inter-optical axis distance D of 12 mm, and the convex lens array 10 has a convex lens (B) with an optical axis. The distance d was set to 8 mm. The reduction ratio of the projected image by this projection element is 2/3, and the enlargement ratio is 3/2.

FIG. 7 is a plan view showing another embodiment of the surface-splitting projection element of the present invention using seven tab prism assemblies, the projection element having a reduction ratio of 87.5% (enlargement ratio of 11).
4%).

In the projection elements shown in FIGS. 1 and 6, the single lenses of the lens arrays 1, 2, 9 and 10 are arranged with a constant optical axis interval. This is an aspect of the present invention. If the optical axis spacing of the convex lenses corresponding to the object plane side and the image plane side is not the requirement of the split projection element but is equal to the ratio of the focal lengths of the respective convex lenses, that is, reduction and enlargement magnification,
The interval may be different depending on the place.

The plane-division projection element of the present invention is a projection element capable of forming a reduced or enlarged image, which is impossible with the projection element using a rod lens array or a three-layer lens array which has been conventionally used. It has a great feature in that it can obtain an image with little chromatic aberration.

[0021]

[Brief description of drawings]

FIG. 1 is a plan view showing an image forming mechanism of an xz plane of a plane division projection element of the present invention.

2 is a plan view showing an image forming mechanism on a yz plane of the projection element in FIG. 1. FIG.

FIG. 3 is a perspective view showing an example in which the projection element of FIG. 1 is used as a sensor.

FIG. 4 is a plan view showing an optical transmission mechanism of a tab prism.

FIG. 5 is a perspective view of a tab prism assembly.

FIG. 6 is a plan view of the xz plane of another example of the surface-division projection element of the present invention.

FIG. 7 is a plan view of the xz plane of another example of the plane-division projection element of the present invention.

[Explanation of symbols]

 1, 2, 9, 10… Convex lens array 3 ………………… Tab prism 4 ………………… Light-shielding body 5 ………………… Object surface 6 ………………… Image plane 7 ……………… Light-shielding plate 8 …………………… Tab prism junction surface 11, 12, …………… Optical axis of convex lens Tc ………………… Conjugate length

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[Procedure amendment]

[Submission date] February 18, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be amended] Claims

[Correction method] Change

[Correction content]

[Claims]

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0004

[Correction method] Change

[Correction content]

[0004]

Therefore, the present inventor has completed the present invention as a result of an examination for the purpose of developing a surface division element having an image enlarging / reducing function. Whereas, two tab prisms are symmetrically assembled so that their light reflecting surfaces are on the outside, and a plurality of tab prism assemblies are arranged linearly so that their light reflecting surfaces face each other. Of the two types of convex lenses having different focal lengths on the light input / output end faces of the tab prism assembly arranged in a circular pattern, and the arrangement interval D of the convex lenses arranged on the light incident end side and the convex lens arranged on the light emitting end side. A surface characterized by being arranged such that the ratio to the array interval d is equal to the ratio of the focal length of the convex lens arranged on the light incident end side to the focal length of the convex lens arranged on the light emitting end side. It is in a split projection element.

[Procedure 3]

[Document name to be amended] Statement

[Name of item to be corrected] 0005

[Correction method] Change

[Correction content]

A cross section of the tab prism 3 used in the present invention is shown in FIG. The light incident at an angle α with the axis of the tab prism is refracted to the light reflecting surface side of the tab prism, and the light reflected on the light reflecting surface is The light is emitted in the inversion direction at an angle α with the axis.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0006

[Correction method] Change

[Correction content]

The angle between the hypotenuse of the tab prism and the bottom surface is θ. When this angle θ becomes large, the light emitted from the object surface is not reflected by the light reflection surface of the tab prism, but is stray light directly emitted from the emission surface. And the contrast of the obtained image is reduced. From this point of view, it is preferable that the angle θ satisfies the condition of θ ≦ 90 ° -sin ⁻¹ (1 / n) (where n is the refractive index of the material forming the tab prism).

[Procedure Amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0007

[Correction method] Change

[Correction content]

Further, the ratio a / b of the length b in the width direction of the tab prism to the length a of the base in the axial direction satisfies [Equation 1], so that the vicinity of the optical axis where the aberration of the lens is small is the most. It is preferable in terms of brightening, but the overall image brightness is a
It becomes brighter when / b is slightly smaller than [Equation 1]. Also,
Image uniformity is sensitive to a / b, and the optimum value varies depending on the focal length of the lens used and the arrangement interval of the tab prism assembly, so experiments or computer simulations should be used to It is better to decide an optimum value that is slightly smaller than the value of 1].

[Equation 1]

[Procedure correction 6]

[Document name to be amended] Statement

[Correction target item name] 0009

[Correction method] Change

[Correction content]

In a line image forming element composed of a lens array, each unit forms an erect image is an essential condition for forming a continuous line image. However, the condition of this erect image is sufficient if it is satisfied only in the line direction of the line image forming element, so in the present invention, the burden on the lens is reduced by using the image inverting action of the tab prism in the line direction, and the chromatic aberration is small. In addition, we succeeded in making a line imaging element that is easy to assemble. In the present invention, the image is inverted in the direction perpendicular to the line direction. However, if an erect image is required, the image may be inverted by using a mirror and used as an erect image.

[Procedure Amendment 7]

[Document name to be amended] Statement

[Correction target item name] 0010

[Correction method] Change

[Correction content]

FIG. 1 is a plan view showing an xz plane and an image forming mechanism of the surface-division projection element of the present invention, FIG. 2 is a plan view of the yz plane and an image forming mechanism, and FIG. 3 is shown. It is the perspective view. Among the reference numerals in these figures, 1 is a convex lens provided at the light incident end of the tab prism assembly, 2 is a convex lens provided at the light emitting end of the tab prism assembly, 3 is a tab prism, 4 is a light blocking member, and 5 is a light shielding member. The object plane and 6 are image planes. Object plane 5, image plane 6
Are at positions separated by the focal lengths from the respective convex lenses, and an inverted image is formed in the y direction as shown in FIG.
In the direction, the tab prism 3 serves to form an erect image as shown in FIG.

[Procedure Amendment 8]

[Document name to be amended] Statement

[Correction target item name] 0011

[Correction method] Change

[Correction content]

Specific examples will be shown for the sake of clarity. Base length 20 mm, base width 5 mm, height 1
Four tab prism assemblies made by joining two polymethylmethacrylate tab prisms with 0 mm and hypotenuse angle θ = 45 ° with a black adhesive so that the top and bottom surfaces match, and the focal length F =
Four 60 mm convex lenses (A) and focal length f = 45 m
4 convex lenses (B) having a thickness of 6.6 mm are provided as shown in FIG.
Were assembled between the tab prism assemblies. Next, place 2 convex lenses (A) so that the optical axis is at the center and 10 mm x 2
Cut it into a rectangle of 0mm, and the other two are 10m which is half of this
Cut into m × 10 mm and set the axial distance D = on the incident side as shown in Fig. 1.
20 mm, and the convex lens (B) is 10 mm ×
Cut into a rectangle of 15 mm, and have an axial distance d = 15 m on the exit side.
m to provide the plane-division projection element of the present invention.

[Procedure Amendment 9]

[Document name to be amended] Statement

[Name of item to be corrected] 0015

[Correction method] Change

[Correction content]

That is, for each projection element, (a) position-angle conversion by the lens (A), (b) angle inversion in the xz plane by the tab prism, and (c) angle-position conversion by the convex lens (B). Inverted f / F only in y direction
Since a doubled image is obtained and the distance between these images is reduced by a factor of f / F (d / D), a continuous inverted image of an inverted f / F is obtained as a whole. Further, the present plane division projection element can also be used as an F / f times magnifying projection element by reversing the object plane and the image plane.

[Procedure Amendment 10]

[Document name to be amended] Statement

[Correction target item name] 0016

[Correction method] Change

[Correction content]

In the plane-division projection element of FIG. 1, the optical axis of the convex lens on the image side is moved inward by d / 2 by the lenses at both ends compared to the optical axis of the convex lens on the object side, and a reduced image is projected. ing. As described above, the reduction length of the projected image of the plane-division projection element of the present invention in which one set of the convex lens array and the array of the tab prism assembly are combined is limited by the pitch of the lens array on the projection side. Therefore, the larger the number of the convex lenses and the tab prism assembly optical units arranged, the larger the limit of the reduction ratio of the projection element. On the other hand, the smaller the number of arrays of the optical units, the smaller the effect of downsizing the apparatus (shortening the projection distance) by performing the plane division and projecting, and thus the number of arrays cannot be reduced so much.

[Procedure Amendment 11]

[Document name to be amended] Statement

[Correction target item name] 0017

[Correction method] Change

[Correction content]

FIG. 6 is a plan view of the xz plane of another example of the plane division projection element of the present invention. In this example, in order to improve the image forming brightness of the projection element, the same tab prism assembly arrangement as that used in FIG. 1 is eliminated, a thin light shielding plate 7 is inserted, and the convex lens arrays 9 and 10 are used. As for the above, a simple convex lens array was not used, but a convex lens of a shape obtained by cutting out a part of a single lens while gradually changing the position was used. Specifically, the focal length F of the convex lens 9 is 60 mm,
The focal length f of the convex lens 10 is 40 mm, the inter-optical axis distance D of the convex lens (A) of the convex lens array 9 is 12 mm, and the inter-optical axis distance d of the convex lens (B) of the convex lens array 10 is 8 mm.
In mm, the reduction ratio of the projected image by this projection element is 2/3, and the enlargement ratio is 3/2.

[Procedure Amendment 12]

[Document name to be amended] Statement

[Correction target item name] 0018

[Correction method] Change

[Correction content]

FIG. 7 is a plan view showing another embodiment of the plane-division projection element of the present invention using eight tab prism assemblies. The reduction magnification of this projection element is 87.5% (the enlargement magnification is 114%). %).

[Procedure Amendment 13]

[Document name to be amended] Statement

[Correction target item name] Explanation of code

[Correction method] Change

[Correction content]

[Explanation of reference numerals] 1, 2, 9, 10 ... Convex lens array 3 …………………… Tab prism 4 …………………… Light-shielding body 5 …………………… Object plane 6 …………………… Image forming surface 7 …………………… Light-shielding plate 8 …………………… Black adhesive 11, 12 ………… Optical axis of convex lens Tc ………… ……… Conjugate length

Claims (1)

[Claims] 1. A plurality of tab prism assemblies which are symmetrically assembled such that two tab prisms having a symmetric trapezoidal cross section are arranged so that their light reflecting surfaces are on the outside, and straight tabs are arranged so that their light reflecting surfaces face each other. The convex-lens array interval D (distance between the lens axes), in which two kinds of convex lenses having different focal lengths are arranged on the light-incident end side, on the light-incident / outgoing end faces of the tab prism assembly arranged in a straight line ) And the array distance d (lens axis distance) of the optical axes of the convex lenses arranged on the light emitting end side, the focal length of the convex lenses arranged on the light incident end side and the A plane-division projection element characterized in that it is arranged so as to be equal to the ratio of the focal lengths of the convex lenses to be provided.