JPH07281122A - Illumination optical device - Google Patents

Abstract

PURPOSE:To reduce a line-bow phenomenon by setting the reflecting surface or the outside shape of a toric mirror and to obtain illumination light whose light quantity is uniform by making the illumination light on the surface of a reading original an almost straight line state. CONSTITUTION:This is an illumination optical device provided with a light source 103 emitting the illumination light for illuminating the original and an optical element provided with a toric surface 11 for condensing the illumination light on the original and arranged so that the illumination light is made incident on the toric surface 11 by some angle. Then, the outside of the toric surface 11 of the optical element is formed like a bow. Besides, the optical element is arranged so that the axis L-L' of the toric surface 11 becomes in parallel with the axis of the illumination light emitted from the toric surface 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image input device for reading image information by photoelectric conversion.

[0002]

2. Description of the Related Art FIG. 15 shows a conventional image input device,
FIG. 16 shows the illumination optical device. The illumination optical device shown in FIG. 16 originally has an optical arrangement as shown in FIG. 17, but the optical path is changed by the two mirrors 102 and 105 so that the optical path is housed in a limited space. ing.

In FIG. 16, one of the two optical path changing mirrors uses a toric mirror 102.
As shown in FIG. 17A, the toric mirror 102
The curved surface R1 illuminates the light beam emitted from the light source 103 at the position of the document surface 101 and illuminates the width of one line. Further, as shown in FIG. 17B, the light source image of the light source 103 is formed at the position of the document surface 101 by the curved surface R2.

As shown in FIG. 15, the light beam emitted from the light source 103 enters the toric mirror 102. This ray is incident at an angle 111 with respect to the axis 110 of the toric mirror. This is to convert the optical axis in the direction of the next optical path conversion mirror 105. The light ray reflected by the toric mirror 102 is the optical path conversion mirror 1.
An image is formed on the document surface 101 via 05.

Image information of a document illuminated by a light beam is imaged on a linear image sensor 109 by a projection lens 108. Hold the document holder 107 in the direction of the arrow (Fig. 15).
The information of the entire document surface is sequentially read by the linear image sensor 109 by moving to.

The light source 103 is constructed as shown in FIG. The stem 202 is fixed to the light source base 201 by brazing. On this stem, multiple LED chips 2
10 are arranged in rows and bonded. Each L
Around the ED chip 210, there is formed a conical reflector portion 202a that reflects light emitted in the lateral direction and emits the light to the upper side of the LED chip 210 (FIG. 18B).

The light source 103 is composed of two LED chip rows 210a and 210b for emitting light of three colors, and one row (6 LEDs) has a small amount of light per LED.
Individual) 210a, and another row 210b is red LE
D and the green LED are arranged in the order of GRGGGRG (see FIG. 18A). LED chips 210a and 210
The light from b is reflected by the reflector 202a and emitted upward from the chip (FIG. 18B), and then reflected by the blue reflection film 205a or the total reflection mirror 205b formed at a predetermined angle and interval. Then, the light is emitted to the front (right side in FIG. 18, left side in FIG. 15) and is condensed by the toric mirror 102 so as to be linear on the document surface (see FIG. 15).

The light from the blue LED is reflected by the blue reflecting film 205a, and the light from the red LED and the green LED is reflected by the total reflection mirror 205b, and is seen from the front of the light source (right side in FIG. 18, left side in FIG. 15). When you do, the three colors will be emitting light from the same position. By electrically controlling the RGB color switching, the original can be read at high speed.

[0009]

In the above-mentioned conventional illumination optical device, the toric mirror 102 has the curved surface R1.
And the ray from ray 103 is a toric mirror 10.
Since the light enters at an angle 111 with respect to the second axis 110, the reflection angle of the light beam differs between the central position and the peripheral position of the toric mirror 102. As a result, the light source image on the document surface 101 becomes a bow.

The toric mirror 102 further has a curved surface R2. Therefore, a bow-shaped light source image on the document surface 101 is linearly condensed, and a so-called line bow phenomenon 110 is generated.
a (see FIG. 8B) occurs. Therefore, the document surface 1
Since the line 111a read by the linear image sensor 109 on 01 is a straight line, there is a drawback that a uniform light amount cannot be obtained in the central portion and the peripheral portion of the reading line 111a. The light amount shown in FIG. 17B shows a state in which the light amount is small in the central portion and large in the peripheral portion, and a uniform light amount cannot be obtained.

The present invention has been made in view of such a situation, and the line bow phenomenon is reduced by setting the reflecting surface and the outer shape of the toric mirror, and the illumination light on the surface of the read document is made substantially linear. The purpose is to obtain a uniform amount of illumination light.

[0012]

In order to achieve the above object, the present invention relates to a first invention, which is a light source for emitting illumination light for illuminating a document and a toric for converging the illumination light on the document. In an illumination optical device having a surface and an optical element arranged so that the illumination light is incident on the toric surface at an angle, the optical element has an outer shape of the toric surface formed into an arc shape. There is.

A second aspect of the invention has a light source for emitting illumination light for illuminating a document and a toric surface for converging the illumination light on the document, and the illumination light is incident on the toric surface at an angle. In the illumination optical device including the optical element arranged as described above, the optical element is arranged such that the axis of the toric surface is parallel to the axis of the illumination light emitted from the toric surface.

[0014]

In the illuminating optical device having the above structure, the shape of the reflecting surface of the toric mirror is formed to cancel the line bow phenomenon. Further, the outer shape of the toric mirror is a curved shape that cancels the line bow phenomenon. As a result, the line bow phenomenon due to the toric mirror can be reduced, and the illumination light on the surface of the read document can be made substantially linear, so that it is possible to obtain a uniform amount of illumination light.

[0015]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a first illumination optical device according to the present invention.
It is the top view and front view which show an Example.

In FIG. 1, the shape and arrangement of the toric mirror 11 are as described below. Conventionally, as shown in FIG. 13A, the normal line N-N 'at the reflection position of the optical axis A-A' and the outlines XX 'and YY' of the mirror are parallel to each other. It had a shape and arrangement. In this case, when viewed from the film surface 101 side, the outer shape of the toric mirror 21 has a curved shape as shown in FIG. 14, which is equivalent to the curved light source being illuminated.

On the other hand, in the first embodiment of the present invention, as shown in FIG. 1, the direction of the reflected ray L-L 'of the optical axis in the optical axis A-A' (light toward the film surface). axis)
Then, the entire mirror 11 is arranged so as to be inclined more than the conventional one so that the outlines X-X 'and Y-Y' of the mirror are parallel to each other. Therefore, when viewed from the film surface direction, the mirror 11 looks like a substantially linear shape as shown in FIG. Thereby, the bending (line bow) of the illumination light at the film surface position is alleviated, and the uneven illumination is not increased.

FIG. 3 shows a second embodiment of the illumination optical device according to the present invention.
It is a front view showing an example. In the conventional illumination optical device and the first embodiment, the reflection surface 61 at the center position (see FIG. 6).
As shown in FIGS. 6C and 6D, the reflection surface 62 at the peripheral position is in a vertically shifted relationship, and the central portion A and the peripheral portion B are not optically equivalent. Absent.
That is, the angle formed by the incident light and the reflected light at the central portion A is
While narrow as shown in FIG. 6C, the angle formed by the incident light and the reflected light at the peripheral portion B has a widening relationship as shown in FIG. 6D.

On the other hand, in the second embodiment of the present invention, as shown in FIG. 4, the reflection curved surface in the lateral direction is not shifted in the central portion and the peripheral portion, and the portion on the same curved surface is used. It's just a difference. That is, the angle formed by the incident light and the reflected light in the central portion A and the angle formed by the incident light and the reflected light in the peripheral portion B are the same, as shown in FIGS. 4 (a) and 4 (b). Further, the outline of the reflecting surface of the mirror 63 is not a straight line but a substantially arcuate shape (curved shape) so that it is substantially linear when viewed from the film surface direction (FIG. 5). As a result, the bending (line bow) of the illumination light at the film surface position is alleviated, the illumination unevenness does not increase, and the central position and the peripheral position are optically equivalent and the illumination unevenness is further reduced.

FIG. 7 shows a third embodiment of the illumination optical device according to the present invention.
It is a perspective view showing an example. FIG. 8 is a front view, a top view, and a side view showing a third embodiment of the illumination optical device according to the present invention. FIG. 9 is a front view showing a third embodiment of the illumination optical device according to the present invention.

In the third embodiment of the present invention, the reflecting surface of the toric mirror 71 is not a toric surface but a biaxial elliptical Fresnel surface 72. Even if the Fresnel surface 72 is formed as described above, it can be made equivalent to a toric surface. Therefore, as in the first and second embodiments, the outer shape and the arrangement of the mirror 71 are substantially linear when viewed from the film surface direction. The line bow can be alleviated by setting so as to be in a shape.

FIG. 10 is a perspective view showing a fourth embodiment of the illumination optical device according to the present invention. FIG. 11 is a front view, a top view, and a side view showing a fourth embodiment of the illumination optical device according to the present invention. FIG. 12 is a front view showing a fourth embodiment of the illumination optical device according to the present invention.

In the fourth embodiment of the present invention, the reflecting surface of the toric mirror 71 is divided into a plurality of Fresnel surfaces 73. Each Fresnel surface is a surface that is Fresnel only in the lateral direction. Even with such a configuration, since it is equivalent to the toric surface, the outer shape and arrangement of the mirror 71 should be substantially linear when seen from the film surface direction, as in the first or second embodiment. If so, the line bow can be mitigated.

Further, the Fresnel surface is divided into strips, and the Fresnel surface 73 (a) at the central position and the Fresnel surfaces 73 (b), (c), (d), (e) at the peripheral positions are respectively separated. If the positions are shifted so that they are substantially linear when viewed from the film surface direction, fine adjustment can be performed so as to obtain a more linear and uniform light source image. Alternatively, the mirror 71 itself can be installed without tilting. 7 to 7.
The Fresnel surface in the third embodiment shown in FIG. 9 can also be obtained by dividing the Fresnel surface into strips to obtain the same effects as in the fourth embodiment.

19 to 22 are a perspective view, a side view, a top view and a perspective view showing a fifth embodiment of the illumination optical device according to the present invention.

In FIG. 19, the shape and arrangement of the toric mirror 91 are as described below.

The toric mirror 91 is a spheroidal surface 9.
The outer shape of the toric surface is formed in a bow shape by using a part of No. 2. The shape of the spheroidal surface 92 is set as described below.

As shown in FIG. 20, when the light source 103 is arranged at the position of the focal point A'on the X-axis and the entrance pupil of the projection lens 108 is arranged at the position of the other focal point A, due to the characteristics of the spheroidal surface, the light source 103. The light beam emitted from the lens is focused on the entrance pupil of the projection lens 108. Further, the center point of the optical axis of the toric mirror 91 is arranged at a point Q on the facing surface of the spheroid, and the center point of one reading line of the document surface 101 is arranged at a point P on the line segment QA.

As shown in FIG. 21, a line segment DE passing through the point P is arranged parallel to the Y axis. The length of the line segment DE corresponds to the length of one read line on the document surface 101. If the radius of the major axis of the ellipse is a and the radius of the minor axis is c, the equation of the spheroid surface is

X ² / a ² + (y ² + z ² ) / c ² = 1 (1)

From the line segment AQ + line segment QA ′ = 2a (2)

C ² + ζ ² = a ² (3)
Is established.

Next, the bow shape of the outer shape of the toric surface of the toric mirror 91 is formed as described below.

Position of the entrance pupil of the imaging lens 108 (point A)
The ray is traced backward, and the trajectory on the spheroidal surface drawn by the ray passing on the line segment DE is used as the basis of the arch shape of the toric surface.

As shown in FIG. 20, a vector f and a vector P are defined.

Vector f = (ζ, 0, 0)

Vector P = (α, β, γ) where α and γ are constants

With k as a parameter, vector AQ = k vector P = k (α, β, γ) vector OQ = vector f + k vector P = (ζ + kα, kβ, kγ) = (x, y, z) (4) Each component of this vector OQ satisfies the equation (1). Also,
As shown in FIG. 21, the components of the vector OQ are substituted into the equation (1) in the range of −b ≦ β ≦ b, and (ζ + kα) ² / a ² + k ² (β ² + γ ² ) / c ² = Solving for 1 (5), (−ζα / a ² ± ((ζα / a ² ) ² − (ζ ² / a ² −1) (α ² / a ² + (β ² + γ ² ) / c ² )) ^1/2 ) ÷ (α ² / a ² + (β ² + γ ² ) / c ² ) = k (6) Then, using the parameter k having β as a variable, the vector OQ Just draw a trail.

AP = 42.02 PQ = 49.20 QA '= 40.95 From the equation (2) a = 66.09 Using the cosine theorem, from the equation ζ = 25.74 (3), c = 60. 87

Further, when QAA '= θ, the X component α of the vector P is α = −41.58 γ = 6.03. By substituting these into the equation (6) to obtain the locus, the toric mirror of FIG. 19 is obtained. It looks like 91. However, b = 1
From 2.225, -12.225 ≦ β ≦ 12.225.

If a slit having the same shape as the linear illumination range of the document surface 101 is arranged on a plane perpendicular to the line segment AQ and including the line segment DE, the slit is traced backward from the point A. The locus of the passing ray on the spheroidal surface 92 forms the bow shape of the outer shape of the toric surface of the toric mirror 91.

The bow shape of the toric surface is changed to the fourth
It is also possible to divide into strips as in the embodiment. Furthermore, as shown in FIG. 23, when the shape in the short side direction is set as follows, the light amount of the reading line on the document surface 101 increases. That is, when considering a cross section including AQ'A ',
An intersection point between the line segment DE and the cross section AQ'A 'is defined as a point P', and an ellipse passing through a point Q'having a focal point position A'and P'is set, and a part of the ellipse centered on the point Q'is shortened. By setting the shape in the side direction, the light amount of the reading line on the document surface 101 increases.

In the embodiment described above, the device in which at least one toric mirror having a toric surface having two main meridians is arranged is described, but the toric surface having one main meridian, a so-called cylindrical surface is provided. The effects of the present invention can be obtained as long as the device has a cylindrical mirror and a cylindrical lens.

[0056]

As described above, according to the present invention, the line bow phenomenon is reduced by setting the reflecting surface and the outer shape of the toric mirror, so that the illumination light on the surface of the read original is made substantially linear. This makes it possible to obtain a uniform amount of illumination light.

[Brief description of drawings]

FIG. 1 is a top view and a front view showing a first embodiment of an illumination optical device according to the present invention.

FIG. 2 is a front view showing a first embodiment of the illumination optical device according to the present invention.

FIG. 3 is a front view showing a second embodiment of the illumination optical device according to the present invention.

FIG. 4 is a front view showing a second embodiment of the illumination optical device according to the present invention.

FIG. 5 is a front view showing a second embodiment of the illumination optical device according to the present invention.

6A and 6B are a top view and a front view showing an example of a conventional illumination optical device.

FIG. 7 is a perspective view showing a third embodiment of the illumination optical device according to the present invention.

FIG. 8 is a top view, a front view, and a side view showing a third embodiment of an illumination optical device according to the present invention.

FIG. 9 is a front view showing a third embodiment of the illumination optical device according to the present invention.

FIG. 10 is a perspective view showing a fourth embodiment of the illumination optical device according to the present invention.

FIG. 11 is a top view, a front view, and a side view showing a fourth embodiment of the illumination optical device according to the present invention.

FIG. 12 is a front view showing a fourth embodiment of the illumination optical device according to the present invention.

13A and 13B are a top view and a front view showing an example of a conventional illumination optical device.

FIG. 14 is a front view showing an example of a conventional illumination optical device.

FIG. 15 is a front view showing an example of a conventional illumination optical device.

FIG. 16 is a perspective view showing an example of a conventional illumination optical device.

FIG. 17 is a top view, a characteristic view, and a front view showing an example of a conventional illumination optical device.

FIG. 18 is a top view and a front view showing an example of a conventional illumination optical device.

FIG. 19 is a perspective view showing a fifth embodiment of the illumination optical device according to the present invention.

FIG. 20 is a side view showing a fifth embodiment of the illumination optical device according to the present invention.

FIG. 21 is a top view showing a fifth embodiment of the illumination optical device according to the present invention.

FIG. 22 is a perspective view showing a fifth embodiment of the illumination optical device according to the present invention.

[Explanation of symbols]

 11 Toric Mirror 21 Toric Mirror 61 Reflective Surface 62 Reflective Surface 63 Mirror 71 Toric Mirror 72 Fresnel Surface 73 Fresnel Surface

Claims (9)

[Claims] 1. A light source that emits illumination light for illuminating a document, and a toric surface for converging the illumination light on the document, wherein the illumination light is at an angle with respect to the toric surface. An illumination optical device comprising an optical element arranged so as to be incident, wherein the optical element has an outer shape of a toric surface formed into an arcuate shape. 2. The illumination optical device according to claim 1, wherein the optical element is a toric surface having two main meridians. 3. The illumination optical device according to claim 1, wherein the optical element is a toric mirror. 4. The illumination optical device according to claim 1, wherein the optical element is a cylindrical mirror. 5. A light source that emits illumination light for illuminating a document, and a toric surface for converging the illumination light on the document, the illumination light being at an angle with respect to the toric surface. In an illumination optical device provided with an optical element arranged so as to be incident, the optical element is arranged so that the axis of the toric surface is parallel to the axis of the illumination light emitted from the toric surface. A characteristic lighting optical device. 6. The illumination optical apparatus according to claim 5, wherein the optical element is a toric surface having two main meridians. 7. The illumination optical apparatus according to claim 5, wherein the optical element is a toric mirror. 8. A light source that emits light, a toric mirror that reflects and condenses the light, a document illuminated by the light from the toric mirror, and a light that passes through the document on a line sensor. In an image reading optical system having a projection optical system for forming an image, the outline of the toric mirror is obtained by backprojecting the image reading line of the line sensor onto the ellipsoid of revolution including the reflecting surface of the toric mirror by the projection optical system. An illumination optical device characterized by being determined based on a line image. 9. The illumination optical device according to claim 8, wherein an outer shape of the toric mirror is a bow shape.