JP2002077538A - Image reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image reader which can easily make illuminance distributions on the surface of a document symmetrical before and after the read position in the scanning direction of the reader. SOLUTION: Reflector pedestals 12 and 13 are positioned so that the cross section of the internal surfaces of the curved sections 12a and 13a of the pedestals 12 and 13 crossing in the longitudinal directions of the pedestals 12 and 13 may constitute parts of an ellipse at one focal point of which a light source 11 is set up while the minor axis of the ellipse is on the optical path of the light. Then one illuminance distribution d1 controlled by the light quantity from the pedestal 12 side and the other illuminance distribution d2 which is controlled by the light quantity from the pedestal 13 side are made symmetrical with respect to the read position P on the document before and after the position P in the scanning direction by respectively selecting the forming and nonforming spots of a reflector 42 and an auxiliary reflector 43 on the internal surfaces of the curved sections 12a and 13a of the pedestals 12 and 13.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical image reading apparatus mounted on a copier, a facsimile machine, a multifunction machine, or used alone, and more particularly to an illuminance distribution on a document surface.

[0002]

2. Description of the Related Art An image forming apparatus such as a copying machine, a facsimile machine, and a multifunction peripheral is equipped with an optical image reading device such as a flatbed scanner. Further, such an image reading device is used alone. FIG. 10 shows a part of the configuration of the image reading apparatus. FIG. 1 shows a configuration in the vicinity of a light source unit that irradiates light to a document surface.
The original is placed on a flat glass table 2, and a light source unit is arranged below the glass table 2 so that the light source unit is orthogonal to the longitudinal direction of the light source 11 and the glass table 2.
Optical scanning is performed by moving in the direction of arrow A, which is parallel to.

The light source unit comprises a light source 11, a reflector 5
2, a reflector base 12 and an enclosing wall 31 are provided. The light source 11 is a fluorescent lamp or a halogen lamp whose longitudinal direction is a direction perpendicular to the scanning direction in the scanning plane, and emits light to irradiate the document surface via the glass table 2. The reflector base 12 and the surrounding wall 31 each have curved portions 12a and 31a that are convex in a direction away from the glass base 2. The curved portion 12a and the curved portion 31a are opposed to each other in the scanning direction, and both of them substantially include the light source 11 between the glass table 2 and the front and rear in the scanning direction along the longitudinal direction. Also,
The reflector base 12 has a flat portion 12b extending in the scanning direction rearward from the uppermost portion of the curved portion 12a in parallel with the glass table 2, and the surrounding wall 31 is located forward of the uppermost portion of the curved portion 31a in the scanning direction. Flat portion 31 extending parallel to glass stand 2
b. Reflector base 12 and surrounding wall 31
With such a configuration, the external light is shielded so that light from a source other than the light source 11 is not irradiated on the original surface when the original is placed. In addition, the curved portion 12a of the reflector base 12
Of the reflected light from the document surface, that is, light to be read, that is, from the reading position P on the document surface, is guided to the subsequent optical system between the lowermost portion of the curved wall 31a and the lowermost portion of the curved portion 31a of the surrounding wall 31. An opening 32 through which reading light, which is reflected light, passes is provided.

[0004] A curved portion 12 of the reflector base 12 is provided.
The inner surface a forms a part of an ellipse in which the light source 11 is disposed at one of the focal points (the focal point on the left side in the figure) having a major axis whose cross section perpendicular to the longitudinal direction is parallel to the scanning direction. And
A reflector 52 is formed along this surface. Accordingly, the cross section of the reflector 52 orthogonal to the longitudinal direction forms a part of the ellipse according to the surface shape inside the curved portion 12a of the reflector base 12. That is, the light source 11 and the reflector base 12 are on the same side with respect to the optical path of the reading light, in the drawing, on the document surface so as to avoid the reading light guided from the document surface to the subsequent optical system. It is provided on the rear side in the scanning direction with respect to the reading position P. The reflector 52 and the reflector base 12 move integrally with the light source during scanning, and the reflector 52 reflects the light of the light source 11 toward the document surface.

[0005]

However, in the above-described conventional image reading apparatus, the illuminance distribution d on the original surface due to the light from the light source 11 can be obtained as the reading light guided from the original surface to the subsequent optical system. The reading position P is deviated to the front in the scanning direction as shown in FIG.
When the light source 11 and the reflector base 12 are located on the opposite side of the reading light from the side shown in the figure, the illuminance distribution d is deviated backward in the scanning direction. As a result, there arises a problem that a shadow occurs at a step on the document surface.

Japanese Unexamined Patent Application Publication No. 9-219769 discloses a configuration in which a light source and a reflector are provided on one side in a scanning direction with respect to a reading optical path from a reading position on a document surface in order to suppress generation of a shadow. A configuration in which an opposing reflecting plate is arranged on the opposite side of the reading optical path is described. However, in this configuration, since the opposing reflection plate is a flat plate, the illuminance distribution on the document surface is not symmetrical around the scanning position in the scanning direction, and it is difficult to sufficiently suppress the generation of shadows. The above publication discloses a configuration using a cylindrical reflecting mirror having an opening formed at a predetermined position, assuming that this configuration causes a decrease in illumination efficiency and an increase in cost. Symmetry in the front and rear directions can suppress the occurrence of shadows. However, in this case, it is necessary to newly set the light source position and the waveguide mechanism by introducing a cylindrical reflecting mirror, and it is difficult to realize the configuration.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and an object of the present invention is to provide an image reading apparatus capable of easily making the illuminance distribution on the original surface symmetrical in the scanning direction of the reading position before and after the scanning direction. To provide.

[0008]

In order to solve the above-mentioned problems, an image reading apparatus according to the present invention optically scans a flat original surface and sets a direction perpendicular to the scanning direction in the scanning surface as a longitudinal direction. A light source, having a surface that moves integrally with the light source, a section orthogonal to the longitudinal direction has a major axis parallel to the scanning direction, and forms a part of an ellipse where the light source is arranged at one of the focal points; A reflector base, and a reflector formed along the surface of the reflector base to reflect the light of the light source toward the original surface, wherein the light source and the reflector base are arranged in a subsequent optical system from the original surface. An image reading device provided on the same side with respect to an optical path of reading light which is reflected light guided to the light source and the reflector base on an opposite side to the optical path of the reading light; Orthogonal to direction An auxiliary reflector base having a surface forming a part of another part of the ellipse whose short axis is placed on the optical path of the reading light, and a light source of the light source formed along the surface of the auxiliary reflector base. An auxiliary reflector that reflects the light toward the document surface, wherein the reading position on the document surface where the reading light is obtained is controlled by the amount of light from the reflector base side biased to one of the front and rear sides in the scanning direction. The reflector serving as the reflector forming portion and the non-reflective surface on the reflector base so that the illuminance distribution of the reflector base and the illuminance distribution controlled by the amount of light from the auxiliary reflector base side biased to the other side are symmetrical. And the non-forming portion of the auxiliary reflector on the auxiliary reflector base and the non-forming portion of the auxiliary reflector serving as a non-reflection surface are selected. That.

According to the above invention, the light source, the reflector base, and the auxiliary reflector base are provided on opposite sides of the optical path of the reading light guided from the document surface to the subsequent optical system. The cross section orthogonal to the longitudinal direction of the surface of the reflector base and the cross section orthogonal to the longitudinal direction of the surface of the auxiliary reflector base each have a major axis parallel to the scanning direction and read the minor axis to read the light. One of the focal points of the ellipse placed on the optical path, that is, a different part of the same ellipse where the light source is located at the focal point closer to the reflector base. The reflector is formed along the surface of the reflector base, and the auxiliary reflector is formed along the surface of the auxiliary reflector base. Thereby, the illuminance distribution controlled by the amount of light from the reflector base side deviated to one of the front and rear in the scanning direction with respect to the reading position on the document surface from which the reading light is obtained, and the auxiliary reflector base deviated to the other side And an illuminance distribution dominated by the amount of light from the side.

[0010] Then, in such a manner that the two illuminance distributions are symmetrical in the scanning direction with respect to the reading position in the scanning direction, the positions where the reflector is formed and where the reflector is not formed on the surface of the reflector base and the surface of the auxiliary reflector base. And where the auxiliary reflector is formed are selected. As a result, the overall illuminance distribution obtained by synthesizing those illuminance distributions is symmetric before and after the reading position in the scanning direction. The introduction of a reflector and an auxiliary reflector to obtain such an illuminance distribution,
This can be performed by determining the position of the auxiliary reflector base with reference to the light source and the reflector base whose positional relationship is already known.

As described above, according to the present invention, with respect to the light source and the reflector base whose positional relationship is known, the surface whose cross section orthogonal to the longitudinal direction of the light source is a part of the same ellipse as the surface of the reflector base is defined. Provide an auxiliary reflector base having, the reflector and the auxiliary reflector, the illuminance distribution governed by the amount of light from the reflector base side, and the illuminance distribution governed by the amount of light from the auxiliary reflector base side, on the document surface Since the configuration is such that the reading position is selectively formed so as to be symmetrical before and after the scanning direction, the entire illuminance distribution can be easily made symmetrical before and after the reading position on the document surface in the scanning direction.

Further, in order to solve the above-mentioned problems, the image reading apparatus of the present invention may be arranged such that the formation area of the reflector on the reflector base is based on the formation area of the auxiliary reflector on the auxiliary reflector base. It is characterized in that the formation part and the non-formation part of the reflector are selected so as to be smaller than the formation area of the auxiliary reflector.

According to the above invention, the formation area of the auxiliary reflector is determined first, and based on this, the formation area and the non-formation area of the reflector are set so that the formation area of the reflector is smaller than the formation area of the auxiliary reflector. Select Therefore, since the light source is provided on the reflector base side, even if the light amount reaching the reflector base from the light source is larger than the light amount reaching the auxiliary reflector base from the light source, the light amount from the reflector base side is reduced. The dominant illuminance distribution and the illuminance distribution dominated by the amount of light from the auxiliary reflector base can be easily made symmetrical before and after the scanning direction of the reading position on the document surface.

Further, in order to solve the above-mentioned problems, the image reading apparatus of the present invention is arranged such that the reflector alternately forms a stripe pattern along the ellipse with a non-formed portion of the reflector, and the reflector is perpendicular to the scanning plane. The reflector base is formed on the surface of the reflector base such that the stripe pattern is symmetrical with respect to a surface bisecting the reflector base in the scanning direction, and the auxiliary reflector is provided on the surface of the auxiliary reflector base. Around the non-formed portion of the auxiliary reflector, which is provided at the center and has a width along the ellipse smaller than the center in the longitudinal direction at both ends, so as to be symmetric with respect to the bisecting plane. By being formed on the surface of the auxiliary reflector base, the illuminance at the reading position is substantially constant along the longitudinal direction. .

According to the invention, the reflector is formed so as to have a stripe pattern as described above, and the auxiliary reflector is formed in relation to the non-formed portion as described above. In order to make the illuminance of the light source substantially constant along the longitudinal direction, the width of each stripe and the interval between adjacent stripes are set on the reflector base side, and the area and non- It is only necessary to set the area of the formation location. Therefore, it is easy to make the illuminance distribution substantially constant in the longitudinal direction of the reading position on the document surface.

Further, in order to solve the above-mentioned problems, the image reading apparatus of the present invention has a light reflecting sheet attached to a surface of the reflector base and a surface of the auxiliary reflector base, and a portion where the reflector is not formed and The portion where the auxiliary reflector is not formed is a pattern printed on the light reflecting sheet with a black color material, and the reflector and the auxiliary reflector are portions excluding the pattern of the light reflecting sheet.

According to the above invention, the formation and non-formation of the reflector and the formation and non-formation of the auxiliary reflector are obtained by printing the pattern of the black color material on the light reflection sheet. Cost can be reduced.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of an image reading apparatus according to the present invention will be described below with reference to FIGS. Note that components having the same functions as the components described in the related art are denoted by the same reference numerals, and description thereof will be omitted.

FIG. 8 shows a configuration example of the image reading apparatus according to the present embodiment. The image reading apparatus 1 shown in FIG. 1 includes a glass table 2, a first carriage 3, a second carriage 4, an imaging lens 5, and a CCD line sensor 6. Further, the first carriage 3 includes a light source 11 and a reflector base 1.
2, a reflector 42, an auxiliary reflector base 13, an auxiliary reflector 43, and a first mirror 14. The configurations of the reflector 42, the auxiliary reflector base 13, and the auxiliary reflector 43, and the positional relationship between them, the light source 11, and the reflector base 12 will be described later. Also, the second
The carriage 4 includes a second mirror 15 and a third mirror 16
have.

When reading an original image, the first carriage 3 is orthogonal to the longitudinal direction of the light source 11 and is
Move in the direction of arrow A which is parallel to. At this time, the light source 11
Optically scans the original surface placed on the gas table 2, and reads out, out of the reflected light from the original surface, the reading light extracted from the opening 44 between the reflector base 12 and the auxiliary reflector base 13 as a first light. The second mirror 15 of the second carriage 4 is
Reflects toward. In the figure, this optical path coincides with the direction of arrow A. When reading the document image, the second carriage 4
It moves in the same arrow A direction as the first carriage 3 at a predetermined speed with respect to the first carriage 3. The second mirror 15 is the first mirror.
The light from the mirror 14 is reflected toward the third mirror 16,
The third mirror 16 reflects this light in a direction opposite to the direction of the arrow A and guides the light to the imaging lens 5. The imaging lens 5 and the CCD line sensor 6 are fixed to the main body of the image reading device 1, and the imaging lens 5 forms light from the third mirror 16 on the CCD line sensor 6. The CCD line sensor 6 converts a light receiving signal into an electric signal and outputs the electric signal. When the image reading device 1 is mounted on a copying machine, a facsimile device, a multifunction device, or the like, the electric signal is input to an image processing device or the like.

FIG. 9 shows another configuration example of the image reading apparatus according to the present embodiment. The image reading device 21 in FIG. 1 includes the glass table 2 and the optical head 22. Further, the optical head 22 includes a light source 11, a reflector base 12, a reflector 42, an auxiliary reflector base 13, an auxiliary reflector 43, a first mirror 23, a second mirror 24,
It has a third mirror 25, an imaging lens 5, and a CCD line sensor 6. In this image reading device 21,
The optical head 22 is moved in the same direction of arrow A as shown in FIG. 8 and in the direction of arrow B opposite thereto without changing the positional relationship of the components of the optical head 22 with respect to each other. I do. First mirror 23, second
The mirror 24 and the third mirror 25 are arranged so as to reflect the reading light taken out from the opening portion 44 between the reflector base 12 and the auxiliary reflector base 13 in the above-described order and guide the reading light to the imaging lens 5. I have.

Next, FIG. 1 shows a configuration near the light source 11 of a flat bed type image reading apparatus such as the image reading apparatuses 1 and 21 described above. In the figure, as described above, the surface inside the curved portion 12a of the reflector base 12 has a long axis whose cross section orthogonal to the longitudinal direction has a long axis parallel to the scanning direction, and the light source 11 is arranged at one of the focal points. It is part of an ellipse. The reflector 42 is a thin reflecting member formed along the surface of the reflector base 12, and a cross section orthogonal to the longitudinal direction forms a part of the ellipse according to the shape of the surface.

The auxiliary reflector base 13 has a curved portion 13a that is convex in the direction away from the glass base 2 and faces the curved portion 12a of the reflector base 12 in the scanning direction. The curved portion 13a is a curved portion. Along with 12a, the light source 11 is substantially included between the glass table 2 and the front and back of the scanning direction along the longitudinal direction. Further, the auxiliary reflector base 13 includes a bending portion 13.
a has a flat portion 13b extending in parallel with the glass table 2 in the scanning direction forward from the uppermost portion. Reflector base 12
The auxiliary reflector base 13 and the auxiliary reflector base 13 shield external light so that light from a source other than the light source 11 is not irradiated to the document surface in a state where the document is placed. In addition, between the lowermost part of the bending part 12a and the lowermost part of the bending part 13a,
An opening 44 through which light to be read out of the reflected light from the document surface, that is, reading light which is reflected light guided from the reading position P on the document surface to the subsequent optical system is provided.

The surface inside the curved portion 13a of the auxiliary reflector base 13 has a cross section orthogonal to the longitudinal direction, and the other surface of the same ellipse when the short axis of the ellipse described above is read and placed on the optical path of the light. Part. In the figure, the inner surface of the curved portion 13a of the auxiliary reflector base 13 is positioned on the curved portion 1 of the reflector base 12 with respect to the surface formed by the reading light.
The arrangement is symmetrical with the surface inside 2a. In addition, the surface inside the curved portion 12a and the surface inside the curved portion 13a are not symmetrical with respect to the plane formed by the reading light, and while maintaining the positional relationship between the long axis, the short axis, and the focal point, Each may be a different part of the same ellipse. The reflector base 12 and the auxiliary reflector base 13 have a shape other than the inner surface of the curved portion 12a and a curved portion 13a.
The shape other than the inner surface a may or may not be symmetric. The auxiliary reflector 43 is a thin reflecting member like the reflector 42, and is formed along the surface inside the curved portion 13a of the auxiliary reflector base 13, so that a cross section orthogonal to the longitudinal direction has a shape of the surface. Form a part of the same ellipse as described above.

With the above arrangement, on the document surface, the light amount from the reflector base 12 side, which is deviated to one of the front and rear sides in the scanning direction (the front side in the scanning direction in the figure) with respect to the reading position P, is controlled. There is an illuminance distribution d1 and an illuminance distribution d2 which is dominated by the amount of light from the auxiliary reflector base 13 side biased to the other side (backward in the scanning direction in the case of FIG. 3). Here, the formation location and non-formation location of the reflector 42 on the surface inside the curved portion 12a of the reflector base 12, and the formation location and non-formation location of the auxiliary reflector 43 on the surface inside the curved portion 13a of the auxiliary reflector base 13. To make the illuminance distribution d1 and the illuminance distribution d2 symmetrical with respect to the reading position P before and after in the scanning direction. The non-formed portions of the reflector 42 and the non-formed portions of the auxiliary reflector 43 are non-reflective surfaces.

The reflector 42 and the auxiliary reflector 43
There are various ways of selecting the formation part and the non-formation part, and it depends on the radiated light intensity distribution of the light source 11, the surface inside the curved part 12a and the area where the surface inside the curved part 13a is provided, and the like. In the cross section of FIG. 3, the entire surface inside the curved portion 12a is selected as a portion where the reflector 42 is formed, and the entire surface inside the curved portion 13a is selected as a portion where the auxiliary reflector 43 is formed. This is the case where the light amount contributing to the illuminance distribution d1 and the light amount contributing to the illuminance distribution d2 do not significantly differ even if the light source 11 is arranged at the focal point on the side closer to the reflector base 12, This can be cited as a selection example in the case where there is a non-formed portion in another portion of the table 12 and the auxiliary reflector base 13 in the longitudinal direction.

As described above, the illuminance distribution d1 and the illuminance distribution d2
Are symmetrical with respect to the reading position P before and after in the scanning direction, and as a result, the total illuminance distribution d obtained by synthesizing those illuminance distributions
0 is symmetrical in the scanning direction of the reading position P before and after. In the figure, the illuminance becomes the maximum at the reading position P, and the illuminance distribution d
An example in which 0 is symmetrical in the scanning direction is shown. The introduction of the reflector 42 and the auxiliary reflector 43 for obtaining such an illuminance distribution d0 is performed by determining the position of the auxiliary reflector base 13 with reference to the light source 11 and the reflector base 12 whose positional relationship is already known. be able to.

As described above, according to the present embodiment, the cross section perpendicular to the longitudinal direction of the light source 11 has the same ellipse as the surface of the reflector base 12 with respect to the light source 11 and the reflector base 12 whose positional relationship is known. An auxiliary reflector base 13 having a part of the surface is provided, and the reflector 42 and the auxiliary reflector 43 are provided with an illuminance distribution d1 controlled by the amount of light from the reflector base 12 side and the amount of light from the auxiliary reflector base 13 side. And the illuminance distribution d2, which is governed by, is selectively formed so as to be symmetrical before and after the scanning direction of the reading position P on the document surface. The reading position P can be made symmetrical before and after the scanning direction.

Further, since the light source 11 is disposed at the focal point on the side closer to the reflector base 12, the illuminance distribution d1
When there is a difference between the amount of light contributing to the illuminance distribution d2 and the amount of light contributing to the illuminance distribution d2, the reflector 42 is formed on the surface of the reflector base 12 with reference to the formation area of the auxiliary reflector 43 on the surface of the auxiliary reflector base 13. It is preferable to select the location where the reflector 42 is formed such that the area is smaller than the area where the auxiliary reflector 43 is formed. In FIG. 2, first, the location where the auxiliary reflector 43 is formed is determined so as to have a width of the distance b along the ellipse, that is, the entire surface inside the curved portion 13 a of the auxiliary reflector base 13. Is formed along the ellipse along the ellipse from the uppermost part of the surface of the reflector base 12 based on the distance a (a <
b) is selected. Therefore, the light source 11
Even if the amount of light reaching the reflector base 12 from the light source 11 becomes larger than the amount of light reaching the auxiliary reflector 13 from the light source 11, the illuminance distribution d governed by the amount of light from the reflector base 12 side
1 and the illuminance distribution d2 governed by the amount of light from the auxiliary reflector base 13 can be easily symmetrical before and after the scanning direction of the reading position P on the document surface. That is, the entire illuminance distribution d0 can be easily made symmetrical before and after the scanning direction of the reading position P on the document surface.

Next, a configuration will be described in which the illuminance at the reading position P is substantially constant along the longitudinal direction while the entire illuminance distribution d0 is symmetrical in the scanning direction of the reading position P on the document surface. In order to achieve such a configuration, a configuration in which a formation location and a non-formation location of the reflector 42 and the auxiliary reflector 43 are selected is used. As shown in FIG.
As for the reflector 42, a stripe pattern along the ellipse is formed alternately with the non-formed portion of the reflector 42. In the same figure, the formation part of the reflector 42 is a white part 42.
In FIG. 7A, the non-formed portion is a hatched portion 42b. This stripe pattern is formed on the surface of the reflector base 12 so as to be symmetrical with respect to a plane S perpendicular to the scanning surface and bisecting the reflector base 12 in the scanning direction, that is, symmetrical in FIG. Have been.

On both sides of the bisecting surface S, the width and the interval of the stripe pattern are not constant, and one end of the reflector base 12 in the longitudinal direction is the image reading device 1.
Assuming that the front side and the other end side of 21 are the rear side, the illuminance at the reading position P is determined to be constant from the front side to the rear side. For example, the illuminance at the reading position P when the reflector 42 and the auxiliary reflector 43 do not exist is
Assuming that as shown in FIG. 4 (a), the width suddenly decreases as approaching the front side and the rear side from the central portion in the longitudinal direction, the reflector 42 in which the width and the interval of the stripe pattern are adjusted is provided. As shown in b), the illuminance can be made constant.

In this embodiment, since the auxiliary reflector 43 is used, in order to make the illuminance at the reading position P substantially constant in combination with the stripe-shaped reflector 42,
Further, the formation location of the auxiliary reflector 43 is defined as shown in FIG. In the figure, a portion where the auxiliary reflector 43 is not formed is provided at the center of the surface of the auxiliary reflector base 13 so that the width along the ellipse is smaller at both ends than at the center in the longitudinal direction. An auxiliary reflector 43 is formed on the surface of the auxiliary reflector base 13 around the non-formed portion so as to be symmetric with respect to the bisecting surface S. In the figure, the formation location of the auxiliary reflector 43 is a white portion 43a, and the non-formation location is a hatched portion 43b. The shape of the portion where the auxiliary reflector 43 is not formed as described above is shown in FIG.
(A) a trapezoid that is convex toward the upper part of the surface of the auxiliary reflector base 13, and (b) a trapezoid that is convex toward the lower part of the surface of the auxiliary reflector base 13, There are various shapes such as a hexagon as shown in FIG. 3C and a shape surrounded by a curved line such as two facing arcs as shown in FIG.

As an example, FIG. 7 shows the effect of improving the illuminance distribution at the reading position P when the shape of the portion where the auxiliary reflector 43 is not formed is a trapezoid as shown in FIG.
On the reflector base 12, the reflector 42 having the above-mentioned stripe pattern is formed. FIG. 7A shows the illuminance distribution of the reading position P when no auxiliary reflector 43 is formed, that is, when the auxiliary reflector 43 is formed on the entire surface of the auxiliary reflector base 13. In this case, the illuminance decreases greatly from the center in the longitudinal direction toward the front side and the rear side of the image reading devices 1 and 21. FIG. 7B shows the illuminance distribution of the reading position P when the portion where the auxiliary reflector 43 is not formed is provided as a rectangle at the center. In this case, a range in which the illuminance is substantially constant appears on the central portion side in the longitudinal direction, but there are places where the illuminance greatly increases and decreases on the front side and the rear side. FIG. 3C shows the illuminance distribution at the reading position P when the shape of the portion where the auxiliary reflector 43 is not formed is the trapezoid. In this case, the illuminance is substantially constant over a wide range from the front side to the rear side. The auxiliary reflector 4 having another shape shown in FIG.
Even at the formation part 3 and the non-formation part 3, substantially the same effect of improving the illuminance distribution can be obtained.

As described above, in the present embodiment, the illuminance at the reading position P on the document surface is made substantially constant along the longitudinal direction. It is only necessary to set the interval between the stripes to be formed, and to set the area of the formed portion and the area of the non-formed portion on the auxiliary reflector base 13 side. Accordingly, it is easy to make the illuminance distribution constant in the longitudinal direction of the reading position P on the document surface.

The above-described portions where the reflector 42 and the auxiliary reflector 43 are formed and where they are not formed can be easily provided by using a light reflecting sheet such as a diffusion sheet on which an aluminum evaporated film is formed. On the light reflection sheet as described above, the respective patterns of the portions where the reflector 42 and the auxiliary reflector 43 are not formed are printed with a black color material such as black ink, and the portions other than the pattern are formed where the reflector 42 and the auxiliary reflector 43 are formed. And it is sufficient. Such a light reflecting sheet is provided on the reflector base 12.
The reflector 42 and the auxiliary reflector 43 are attached to the surface of the
The cost can be reduced when obtaining the formed part and the non-formed part.

[0036]

As described above, the image reading apparatus of the present invention is provided on the side opposite to the light source and the reflector base with respect to the optical path of the reading light, and the cross section orthogonal to the longitudinal direction is a short axis. An auxiliary reflector base having a surface forming another part of the ellipse placed on the optical path of the reading light, and the light of the light source formed along the surface of the auxiliary reflector base toward the original surface Further having an auxiliary reflector to reflect, with respect to the reading position on the document surface from which the reading light is obtained, the illuminance distribution controlled by the amount of light from the reflector base side biased to one of the front and rear in the scanning direction, The reflector serving as a non-reflective surface and the location where the reflector is formed on the reflector base so that the illuminance distribution controlled by the amount of light from the auxiliary reflector base side biased to the other side is symmetric. A non-formation portion is configured such that the non-formation portion of the auxiliary reflector serving as the formation of secondary reflector portion and non-reflective surfaces on the auxiliary reflector base is selected.

Therefore, in order to make the overall illuminance distribution symmetrical before and after the scanning direction of the reading position on the document surface, a cross section perpendicular to the longitudinal direction of the light source is required for the light source and the reflector base whose positional relationship is known. Provide an auxiliary reflector base having a surface that becomes a part of the same ellipse as the surface of the reflector base,
The illuminance distribution governed by the amount of light from the reflector base and the illuminance distribution governed by the amount of light from the auxiliary reflector base are symmetrical in the scanning direction of the reading position on the document surface between the reflector and the auxiliary reflector. It is only necessary to form them selectively so that Therefore, there is an effect that the entire illuminance distribution can be easily made symmetrical before and after the scanning direction of the reading position on the document surface.

Further, as described above, according to the image reading apparatus of the present invention, the formation area of the reflector on the reflector base is determined by the area of the auxiliary reflector on the basis of the formation area of the auxiliary reflector on the auxiliary reflector base. This is a configuration in which the formation location of the reflector is selected so as to be smaller than the formation area.

Therefore, since the light source is provided on the reflector base side, even if the amount of light reaching the reflector base from the light source is larger than the amount of light reaching the auxiliary reflector base from the light source, the reflector base side And the illuminance distribution dominated by the amount of light from the auxiliary reflector base can be easily symmetrical before and after the scanning position of the reading position on the document surface. Play.

Further, in the image reading apparatus of the present invention, as described above, the reflector forms a stripe pattern along the ellipse alternately with the non-formed portion of the reflector,
The reflector base is formed on the surface of the reflector base such that the stripe pattern is symmetrical with respect to a plane perpendicular to the scanning surface and bisecting the reflector base in the scanning direction,
The auxiliary reflector is provided at the center of the surface of the auxiliary reflector base, and the width along the ellipse is smaller at both ends than the center in the longitudinal direction. The illuminance at the reading position is substantially constant along the longitudinal direction by being formed on the surface of the auxiliary reflector base so as to be symmetrical with respect to a bisecting plane.

Therefore, in order to make the illuminance at the reading position on the document surface substantially constant along the longitudinal direction, the width of each stripe and the interval between adjacent stripes are set on the reflector base side. On the auxiliary reflector base side, it is only necessary to set the area of the formed portion and the area of the non-formed portion. Therefore, it is easy to make the illuminance distribution substantially constant in the longitudinal direction of the reading position on the document surface.

Further, as described above, in the image reading apparatus of the present invention, a light reflecting sheet is adhered to the surface of the reflector base and the surface of the auxiliary reflector base, and the portion where the reflector is not formed and the auxiliary reflector Is a pattern printed on the light reflecting sheet with a black color material, and the reflector and the auxiliary reflector are portions other than the pattern on the light reflecting sheet.

Therefore, there is an effect that the cost can be reduced when obtaining the locations where the reflector and the auxiliary reflector are formed and where they are not formed.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a configuration of a main part of an image reading apparatus according to an embodiment of the present invention, together with an illuminance distribution in a scanning direction.

FIG. 2 is a cross-sectional view showing another configuration of a main part of the image reading apparatus according to the embodiment of the present invention, together with an illuminance distribution in a scanning direction.

FIG. 3 is a plan view showing a configuration of a reflector in a main part of FIG. 1 or FIG. 2;

FIGS. 4A and 4B are graphs for explaining an improvement in illuminance distribution at a reading position when the reflector shown in FIG. 3 is used.

FIG. 5 is a plan view showing a configuration of an auxiliary reflector combined with the reflector of FIG. 3;

FIGS. 6A to 6D are plan views illustrating types of configurations used as the auxiliary reflector in FIG.

FIGS. 7A to 7C are graphs illustrating the improvement of the illuminance distribution at the reading position when the auxiliary reflector of FIG. 5 is used together with the reflector of FIG. 3;

FIG. 8 is a cross-sectional view illustrating a configuration of an image reading apparatus including a main part in FIG. 1 or FIG.

FIG. 9 is a cross-sectional view illustrating another configuration of an image reading apparatus including the main part of FIG. 1 or FIG.

FIG. 10 is a cross-sectional view illustrating a configuration of a main part of a conventional image reading apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Image reading device 11 Light source 12 Reflector base 13 Auxiliary reflector base 21 Image reading device 42 Reflector 43 Auxiliary reflector d0 Illuminance distribution d1 Illuminance distribution d2 Illuminance distribution P Reading position S 2

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G06T 1/00 420 G06T 1/00 420F H04N 1/10 H04N 1/10 1/107 F term (reference) 2H052 BA03 BA09 BA13 2H108 AA01 CB01 GA02 GA09 HA05 2H109 AA02 AA15 AA55 AA59 AA69 5B047 AA01 BA02 BB02 BC09 BC12 5C072 AA01 BA20 CA02 CA15 DA04 DA21 MA01 XA01

Claims (4)

[Claims] 1. A light source which optically scans a flat original surface and has a longitudinal direction extending in a direction perpendicular to the scanning direction in the scanning surface, and a light source which moves integrally with the light source and has a cross section perpendicular to the longitudinal direction. A reflector base having a major axis parallel to the scanning direction and having a surface forming a part of an ellipse where the light source is disposed at one of the focal points; and a light source of the light source formed along the surface of the reflector base. And a reflector that reflects the light toward the original surface,
In the image reading apparatus, wherein the light source and the reflector base are provided on the same side with respect to an optical path of read light which is reflected light guided from a document surface to a subsequent optical system, wherein the optical path of the read light is An auxiliary reflector base provided on the side opposite to the light source and the reflector base and having a surface that forms a part of another part of the ellipse whose cross section orthogonal to the longitudinal direction has a short axis on the optical path of the reading light; And, further comprising an auxiliary reflector formed along the surface of the auxiliary reflector base and reflecting the light of the light source toward the original surface, for a reading position on the original surface where the reading light is obtained, The illuminance distribution dominated by the amount of light from the reflector base side biased to one of the front and back in the scanning direction and the illuminance distribution dominated by the amount of light from the auxiliary reflector base side biased to the other are symmetric. The reflector is formed on the reflector base and the reflector is formed as a non-reflection surface, and the auxiliary reflector is formed on the auxiliary reflector base and the auxiliary is formed as a non-reflection surface. An image reading apparatus, wherein a portion where a reflector is not formed is selected. 2. The formation of the reflector such that the formation area of the reflector on the reflector base is smaller than the formation area of the auxiliary reflector on the basis of the formation area of the auxiliary reflector on the auxiliary reflector base. The image reading apparatus according to claim 1, wherein a portion and a non-formed portion are selected. 3. The reflector according to claim 1, wherein the reflector alternately forms a stripe pattern along the ellipse with a portion where the reflector is not formed, and is perpendicular to the scanning surface and bisects the reflector base in the scanning direction. The stripe pattern is formed on the surface of the reflector base so as to be symmetrical, and the auxiliary reflector is provided at the center of the surface of the auxiliary reflector base and the width along the ellipse is the center in the longitudinal direction. By forming the auxiliary reflector base on the surface of the auxiliary reflector base so as to be symmetrical with respect to the bisecting surface, around the non-formed portion of the auxiliary reflector having a smaller shape on both end sides than the portion, 3. The image reading apparatus according to claim 1, wherein the illuminance at the reading position is substantially constant along the longitudinal direction. 4. A light reflecting sheet is adhered to the surface of the reflector base and the surface of the auxiliary reflector base, and the portions where the reflector is not formed and the portions where the auxiliary reflector is not formed are black on the light reflecting sheet. 4. The image reading device according to claim 1, wherein the image reading device is a pattern printed with a coloring material, and the reflector and the auxiliary reflector are portions other than the pattern of the light reflection sheet.