JP3258096B2 - Imaging element - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a facsimile, a copier,
The present invention relates to an imaging device capable of forming an erect equal-magnification image that can be used as an image transmission body of an LED printer, a liquid crystal printer, or the like.

[0002]

2. Description of the Related Art Conventionally, copiers, facsimiles, LEs
Small image transmitters are used in D printers, liquid crystal printers, and the like, and the following image transmitters are used.

[0003] A gradient index rod-shaped lens element array; a rod-shaped lens element array in which a large number of gradient index rod-type lenses whose refractive index decreases from the center axis of the rod-shaped lens toward the outer periphery is used in parallel as an imaging element. thing.

[0004] Spherical lens array; there is a spherical lens array using as an image forming element a multilayer plate in which three or more spherical lens portions are formed on a flat plate surface, and these inventions are disclosed in Japanese Patent Publication No. 49-8893, This is disclosed in JP-A-57-66414 and JP-A-57-104923.

[0005] roof prism array; JP 56-117
No. 201, JP-A-56-126801, JP-A-56-140301, JP-A-56-14900
No. 2, JP-A-60-254018, JP-A-6-254018
Japanese Patent Application Laid-Open Nos. 0-2554019, JP-A-60-254020, JP-A-61-210319, and JP-A-62-210319.
91902 JP, are shown array using imaging device capable of imaging the erect image of a combination of a roof prism and lens in JP-A-62-201417.

[0006]

An image transmission body composed of a refractive index distribution type rod-shaped lens array requires a long time to manufacture the rod-shaped lens itself, and the integration of the refraction angles of light beams in light transmission becomes large. Therefore, there is a disadvantage that chromatic aberration of image formation is increased. In addition, the laminated body array of spherical lenses
It is difficult to align the optical axis of the three lens across the array General, also tends chromatic aberration of the imaging increases.
Further, in the previously developed by Dove prism array or roof mirror array has a small accumulation of the refraction angle of the light beam during optical transmission, albeit advantage small imaging chromatic aberration is obtained, the Dove prism and the lens There is a drawback that alignment is difficult.

[0007]

Accordingly, the present inventor has proposed an imaging element having a relatively simple structure and capable of forming an erect equal-magnification image having less chromatic aberration than chromatic aberration of an image obtained by a rod lens array. As a result of study for the purpose of developing a child, the present invention was completed.

[0008] It is an aspect of the present invention, the two cross-section symmetrical trapezoid Dove prisms, the joined Dove prism assembly 2 has as its light reflecting surface is outside, in series, the combined optical axis And a convex lens having the same focal length is disposed on each of the light input and output end faces of the series combination of the Dove prism assemblies in which the light reflection surfaces of the two Dove prisms are orthogonal to each other. An imaging element capable of forming a 1: 1 magnification image.

[0009] Hereinafter, a more detailed description of the present invention with reference to the accompanying drawings.

FIG . 3 shows a plan view and an optical path of a trapezoidal Dove prism having a symmetrical cross section, which is a main component of the imaging element of the present invention. Light incident at an angle of α with the optical axis of the Dove prism is refracted at one oblique side at an angle θ, reaches the light reflection surface of the Dove prism, and has the same size as the incident angle of light due to the effect of the trapezoidal prism with a symmetrical cross section. As reflected light at the angle of reflection
It is refracted at the other of the angle θ becomes the hypotenuse of the Dove prism, da
With respect to the optical axis of the probe prism is emitted as outgoing light angle at which alpha. That is, it is a function of reversing the angle of light.

The angle θ between the base and the hypotenuse of the Dove prism
Is preferably as large as possible in order to obtain an image with less chromatic aberration, but if a Dove prism having an abnormally large angle θ is used, it is bent in the oblique side of the Dove prism toward the light reflecting surface. A component (stray light) having a size that cannot be reflected by the light reflecting surface at the angle of the generated light is generated, and the light use efficiency is undesirably reduced. From such a viewpoint, the inclination angle θ
Satisfies the relationship of θ ≦ 90 ° −sin ⁻¹ (1 / n), where n is the refractive index of the material constituting the Dove prism.

Further, the length a in the axial direction of the Dove prism,
When the ratio a / b to the length b in the width direction satisfies the requirement specified by [Equation 1], it is possible to obtain a bright image with the least chromatic aberration.

(Equation 1)

FIG . 1 is a perspective view showing an example of the imaging element of the present invention. Reference numerals 3 and 4 denote a Dove prism assembly in which two Dove prisms each having a light-shielding surface 6 are joined by a black adhesive surface 5 so that the light reflection surface is on the outside. The two dub pre <br/> prism assembly equal in the optical axis in series, is coupled to the light reflecting surface are orthogonal to each other, equal convex lens attachment each of the light incident and emitting end face to the focal length The structure has been adopted. Reference numeral 7 denotes an object plane, and 8 denotes an imaging plane.

FIG . 2 is a plan view showing an image forming mechanism of the image forming element of the present invention, and FIG. 2A is an explanatory view of an xz plane.
(b) is an explanatory diagram of the yz plane. This imaging element was created
The Dove prism, base length 2.5cm Dove prism,
A convex lens having an upper base length of 1.25 cm, a width of 0.65 cm, and an oblique angle θ = 45 ° was used, and a convex lens having a focal length of 2.5 cm was used.

[0015] In FIG. 2 (a), the light emitted from the point x ₁ on the object the optical axis of the imaging element by the action of the convex lens 1 (z-axis)
Angle _{^{-tan -1 (x 1 '/ f}} ), and (where, f is the focal length of the convex lens 1 or 2) is converted into a parallel light forming the hypotenuse of the light incident side of the double pre <br/> prism 3 And it becomes light toward the reflective surface,
The angle formed by the light reflecting surface of the Dove prism and the optical axis
The light becomes parallel light of tan ^-1 (x ₁ / f), and is refracted by the oblique side of the Dove prism 3 on the light emitting end side. The parallel light emitted from the Dove prism 3 is incident on the Dove prism assembly 4, the light passing through the double prism <br/> the arm 4 as parallel light, the convex lens 2 provided on the light emitting end side of the Dove prism 4 The light is condensed by the action, and forms an erect image at the coordinate x ₁ ′ on the image plane. Light emitted from the center point 0 on the object, the spectral effect of a convex lens 1 as described above, at an angle reversal action of dove prism 3 becomes parallel light components to the optical axis of the double prism <br/> arm 4, after passing through the Dove prism 4, is condensed by the convex lens 2 provided on the light emitting end side of the Dove prism 4, it is focused as erect image to the center point 0 'on the imaging.

[0016] In FIG. 2 (b), the point y ₁ on the object, the spectral light by a convex lens in exactly the opposite stroke the optical transmission mechanism of the xz plane of the imaging element, the angle conversion effect of the light by the Dove prism Also, an image is formed as an erect equal-magnification image at a point y ₁ ′ on the real image by the light condensing action of the convex lens. The midpoint 0 on the object is also formed as an erect equal-magnification image at the midpoint 0 'on the image by the same action.

[0017] That is, the combined optical axis two dove prism assembly in series, joined to the light reflecting surface of the Dove prism assembly are perpendicular to each other, to the light incident and emitting faces, equal convex lens having a focal length Is provided on the xz plane and the yz plane of the imaging element.
(A) position-angle conversion action by the convex lens 1;
(B) Angle conversion by Dove prism, (c) Convex lens 2
, And an erect equal-magnification image can be formed in both the x-axis direction and the y-axis direction.

[0018] indicates that the information of the position between this is from the lens 1 and the lens 2 has no meaning, which has led to the optical stability of the imaging element. That is, in FIG. 2, even if the position of the lens 1 or the lens 2 is slightly shifted in the x and y directions, it only appears as a parallel movement of the image, and the image quality itself hardly changes. The most problematic problem in assembling a lens array is that fluctuations in pitch between lenses are accumulated in the array direction and cause a non-negligible optical axis shift. The imaging element array is characterized by being hardly affected by the optical axis shift in the arrangement direction. FIG. 4 is a perspective view showing an example of an imaging element array in which a plurality of imaging elements of the present invention are arranged in the x-axis direction.

FIG . 5 shows a configuration in which two Dove prism assemblies are combined with their light reflecting portions to form one angle conversion member.
An image forming element according to the present invention, wherein the two angle converting members are aligned so that their optical axes are aligned and their light reflecting surfaces are perpendicular to each other, and convex lenses having the same focal length are provided on the light input / output end faces of the combined body. It is a perspective view which shows another example of. As described above, by using the imaging element having a configuration using a plurality of Dove prism assemblies, it is possible to reduce the ratio of the distance between the two convex lenses provided on the light entrance and exit end faces of the imaging element to the width of the lens. The image area that can be projected and projected is wider than the imaging element shown in FIG. As a result, the imaging element array can form a brighter image.

FIG . 6 is a perspective view showing another example of the imaging element of the present invention. In this type of imaging element, the projection area only in the x-axis direction does not expand, and the projection area in the y-axis direction is the same as the projection area of the imaging element in FIG. 1, and when used as an array as shown in FIG. effective.

In the imaging element of the present invention, an imaging element which has been conventionally developed utilizes the refraction of light, whereas an image is obtained by utilizing image reversal using reflection. Therefore, it is of great significance that the imaging of the lens is light, the imaging with little chromatic aberration is obtained, and the imaging of the erect equal-magnification image, which is considered impossible with the imaging element using the Dove prism, is obtained. is there.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an example of an imaging element of the present invention.

FIG. 2 is a plan view showing an imaging mechanism of the imaging device of FIG. 1;

3 is a plan view of a double prism <br/> arm which is a component of the imaging device of the present invention.

FIG. 4 is a perspective view showing one example of an array of the imaging elements of FIG. 1;

FIG. 5 is a perspective view showing another embodiment of the imaging element of the present invention.

FIG. 6 is a perspective view showing another embodiment of the imaging element of the present invention.

[Explanation of symbols]

1, 2,..., Convex lens 3, 4,..., Dove prism assembly 5,..., Black bonding portion 6,..., Light reflecting surface 7,..., Object surface 8,. …………… Image plane

Claims (1)

(57) [Claims] 1. A two- dove prism assembly in which two dove prisms each having a trapezoidal cross section and two light-reflecting surfaces facing outward are joined, and the optical axes of the two dove prism assemblies are equal. Coupled in series so that the reflecting surfaces are orthogonal,
On the light input / output end face of the series combination of the Dove prism assembly,
An imaging element comprising convex lenses having the same focal length.