JP2006087077A - Original illuminator, and image reader - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To remarkably reduce irradiation out of a light flux irradiation area on an original surface by converging light flux from a long light source to above area without expanding an original illuminator having a large quantity of original irradiating light. <P>SOLUTION: There are provided a first reflective plate 15A, comprising two long light sources 13, for reflective light flux of the long light sources, respectively as a reflecting plate and a second reflective plate 15B for irradiating an original surface with converged light flux reflected on the first reflective plate. The light flux from the two long light sources is reflected on the first reflective plate and converged by the second reflecting plate to irradiate the original surface therewith. The first reflective plate and the second reflective plate are made elliptical, respectively and disposed with one of mutual focal points thereof as a common position. Thus, the light flux from each of the long light sources is converged in a light flux radiation area B on the original sources, the useless irradiation of the original surface, other than the light flux irradiation area, is reduced, light flux to cause flare light is decreased and a density difference of read image information is further prevented from becoming large, so that original reading reproducibility can be more improved. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image reading apparatus that is provided in an image forming apparatus such as a copying machine, a facsimile, or a complex machine thereof, and reads an image content on a document surface. The present invention also relates to an original illuminating apparatus that collects a light beam from a long light source such as a fluorescent lamp and irradiates the original surface in such an image reading apparatus.

  2. Description of the Related Art Conventionally, an image forming apparatus such as a copying machine is provided with an image reading device for reading the contents of a document. In this type of image reading apparatus, for example, a fluorescent lamp is used as the long light source, and a xenon lamp is generally used as the fluorescent lamp. A xenon lamp having a diameter of about 10 mm is often used. This xenon lamp has a lower luminance than a halogen lamp, but has a large amount of emitted light due to the large area of a portion emitting visible light, and has high luminous efficiency with respect to power consumption.

  The amount of emitted light is substantially proportional to the area where the fluorescent paint is applied. Therefore, if the diameter of the glass tube is increased and the fluorescent paint is applied more widely, the amount of emitted light can be increased. However, if the diameter of the glass tube is increased, the document illumination device becomes larger, and the image reading device becomes larger.

  FIG. 8 shows a schematic configuration of a main part of a conventional image reading apparatus, and FIG. 9 shows a longitudinal section of a xenon lamp used in a document illumination device of the image reading apparatus.

  As can be seen from the figure, a general document illumination device includes one xenon lamp 1 and one reflector 2. The xenon lamp 1 uses a cylindrical transparent glass tube 3 having a thickness of about 0.5 to 1 mm, and a fluorescent paint 4 is applied to an inner peripheral surface thereof except for an opening angle range of an angle θ to form an aperture (opening portion). ) 5 and xenon gas are sealed inside, and the counter electrodes 6 and 7 are provided on the outer peripheral surfaces on both sides of the aperture 5.

  A discharge is generated by applying an AC voltage of several hundred volts to the counter electrodes 6 and 7, and electrons flowing through the discharge collide with xenon atoms and generate ultraviolet rays when passing through the inside of the glass tube 3. When the fluorescent paint 4 is irradiated with ultraviolet rays, the fluorescent material is excited to emit visible light, and a light beam is emitted from the aperture 5 to the outside. A part of the light beam radiated to the outside irradiates the reading area a on the document surface of the document placed on the document placement transparent glass 8 via the reflector 2 as indicated by L1 in FIG. The remaining part of the luminous flux directly irradiates the reading area a with the luminous flux emitted to the outside from the xenon lamp 1, as indicated by L2 in FIG. The reflected light from the document surface passes through the imaging lens from the first mirror 9 via the second mirror and the third mirror (not shown) as indicated by L3 in FIG. Read as image information.

JP 11-196231 A JP 2004-70187 A

  However, for example, in a high-speed full-color scanner having high productivity, it is necessary to increase a document illumination light amount. However, in order to secure a high amount of light with the xenon lamp 1, the paint area of the fluorescent paint 4 must be increased, that is, the diameter of the glass tube 3 must be increased and a large amount of current must be applied. When the diameter of the glass tube 3 is increased, the area of the aperture 5 is increased, so that the reflecting plate 2 must be increased, and there is a problem that the entire document illumination device is considerably increased in size.

  Further, since the xenon lamp 1 has a large light emitting area and emits a light beam from the aperture 5, it is difficult to diffuse the emitted light beam and condense it on the reading area a which is a light beam irradiation area. For example, in the conventional example shown in FIG. 8, the xenon lamp 1 irradiates the unnecessary area b, and the reflected light beam irradiates the original surface again via the xenon lamp 1 and the reflecting plate 2.

  When the amount of the reflected light beam is large, the illumination light amount changes depending on the density of the document. For example, the density is lower when the document is low, and the density is higher when the document is high. That is, there is a problem that the density difference of the read image information is larger than the density difference of the document, and the document reading reproducibility for reading and reproducing the document content is deteriorated.

  SUMMARY OF THE INVENTION Accordingly, a first object of the present invention is to irradiate a light beam from a long light source on a light beam irradiation area on the original by irradiating a light beam irradiation area other than the light beam irradiation area in a document illuminating apparatus that requires a large amount of light for document illumination. Is to reduce the size significantly and enable miniaturization.

  Similarly, the second object of the present invention is to improve the light collecting performance of the light beam of the long light source to reduce unnecessary light beam irradiation, and to reduce the reflector by increasing the effective light beam, The document illumination device is to be further downsized. A third object of the present invention is to facilitate the replacement of the long light source and improve the maintainability.

  A fourth object of the present invention is to provide a high-productivity, high-speed readable image reading apparatus that condenses a light beam from a long light source in a reading area and significantly reduces the irradiation of the area other than the reading area on the document. Thus, it is possible to reduce the size and reduce the density difference of the read image information and improve the document reproducibility.

For this reason, in order to achieve the first object described above, the invention described in claim 1 is a document illuminating apparatus that irradiates the surface of a document by condensing a light beam from a long light source with a reflector.
Two long light sources are provided, a reflecting plate is provided for each long light source, and each of the reflecting plates has an elliptical shape. Then, the light beams from the two long light sources are condensed by an elliptical reflecting plate provided for each long light source, and irradiated on the document surface.

  According to a second aspect of the present invention, in order to achieve the second object described above, in the document illuminating device according to the first aspect, one focal point of each of the elliptical reflectors is set to the center of the long light source. The first focal point is arranged on a straight line connecting the center of the aperture, and the other focal point is arranged in the vicinity of the light beam irradiation area on the original surface.

  According to a third aspect of the present invention, in order to achieve the first object described above, in the original illuminating apparatus according to the first or second aspect, the light beam from the long light source irradiates a region other than the light beam irradiation region on the original surface. It is characterized by comprising a light beam shielding member that prevents the above. Then, the light beam shielding member shields the area other than the light beam irradiation area on the document surface, and prevents the light beam from the long light source from being irradiated outside the light beam irradiation area.

According to a fourth aspect of the present invention, in order to achieve the first object described above, a document illumination device that irradiates a document surface by condensing a light beam from a long light source with a reflecting plate,
Two long light sources are provided, and as a reflecting plate, a first reflecting plate that reflects a light beam of the long light source and a light beam reflected by the first reflecting plate are condensed and irradiated on the document surface. And a second reflector. Then, the light beams from the two long light sources are reflected by the first reflecting plate, condensed by the second reflecting plate, and irradiated on the document surface.

  According to a fifth aspect of the present invention, in order to achieve the first object described above, in the document illuminating device according to the fourth aspect, the first reflecting plate and the second reflecting plate are each in an elliptical shape, and both of them are mutually connected. One of the focal points is arranged as a common position. Then, the light beams from the two long light sources are condensed by the elliptical first reflecting plate and the second reflecting plate, respectively, and irradiated on the document surface.

  The invention described in claim 6 provides the document illumination device according to any one of claims 1 to 5 in which two identical light sources are provided as the long light source in order to achieve the third object described above. It is characterized by. And when exchanging any long light source, it replaces with the same thing without distinction.

  According to a seventh aspect of the present invention, in order to achieve the fourth object described above, the image reading apparatus includes the original illumination device according to any one of the first to sixth aspects, and reflects reflected light from the original surface. It is characterized by being reflected by a mirror and guided to an image sensor. Then, the light beam from the long light source is condensed by the reflecting plate and irradiated on the document surface, and the reflected light from the document surface is reflected by the mirror and guided to the image sensor.

  According to an eighth aspect of the present invention, in order to achieve the fourth object described above, in the image reading apparatus according to the seventh aspect, a light beam other than the reflected light from the original surface is provided in the optical path of the reflected light from the original surface. The light beam shielding portion for preventing the light from entering is formed by a reflecting plate. Then, the light beam shielding portion formed on the reflection plate prevents light beams other than the reflected light from the document surface from entering the optical path of the reflected light from the document surface.

  According to a ninth aspect of the present invention, in order to achieve the fourth object described above, in the image reading device according to the seventh or eighth aspect, a long light source and a light source on both sides of the optical path of the reflected light from the document surface are provided. Both reflectors are provided symmetrically. Then, the light beams from the two long light sources are collected by the reflecting plates, respectively, and irradiated on the document surface from both sides across the optical path of the reflected light from the document surface.

  According to the first aspect of the present invention, since the two long light sources are provided and the original surface is irradiated with the light beams from the two long light sources, each long light source can be used even in a document illumination device that requires a document illumination light amount. A sufficient amount of light can be ensured without the need to increase the size of the light source together with the reflector, and the size can be reduced. In addition, since the luminous flux from the long light source is condensed by the elliptical reflecting plate provided for each long light source and irradiated on the original surface, the diffused light from each long light source is reflected on the elliptical reflecting plate. Thus, it is possible to significantly reduce the amount of light that is condensed and irradiated to areas other than the light beam irradiation region, prevent an increase in the density difference of the read image information, and improve the document reading reproducibility for reading and reproducing the document contents.

  According to the second aspect of the present invention, one focal point of each of the elliptical reflectors is arranged on a straight line connecting the center of the long light source and the center of the aperture, while the other focal point is arranged. Since it is placed near the light beam irradiation area on the document surface, the light collecting performance of the long light source is improved, unnecessary light beam irradiation is reduced, and the reflector is made smaller by increasing the effective light beam. The document illumination device can be downsized.

  According to the third aspect of the present invention, since the light flux from the long light source is prevented from irradiating the area other than the light flux irradiation area, it effectively cuts unnecessary reflected light from entering the light flux irradiation area, It is possible to further prevent the density difference of the read image information from increasing, and to further improve the document reading reproducibility.

  According to the fourth aspect of the present invention, since the two long light sources are provided and the original surface is irradiated with the light beams from the two long light sources, each long light source is provided even in the document illumination device that requires a document illumination light amount. A sufficient amount of light can be ensured without the need to increase the size of the light source together with the reflector, and the size can be reduced. Further, since the light beam from the long light source is reflected by the first reflecting plate, condensed by the second reflecting plate, and irradiated on the document surface, the diffused light from each long light source is reflected in two ways. It is possible to reliably condense the light with the plate and significantly reduce the irradiation to areas other than the light beam irradiation area, prevent an increase in the density difference of the read image information, and improve the document reading reproducibility.

  According to the fifth aspect of the present invention, the first reflector and the second reflector are each elliptical, and one of the focal points is disposed at a common position, and the light beams from the two long light sources are emitted. Since each of the elliptical first and second reflectors reliably collects the light and irradiates the original surface, the density difference of the read image information is further prevented from being increased, and the original is further read. Reproducibility can be improved.

  According to the sixth aspect of the present invention, two identical light sources are used as long light sources, and when replacing any long light source, the same light source is replaced without distinction. When it is damaged, the long light source can be replaced as a single unit without being distinguished from each other, facilitating replacement and improving maintainability.

  According to the invention described in claim 7, the document illuminating device according to any one of claims 1 to 6 is provided, the light beam from the long light source is condensed by the reflecting plate and irradiated on the document surface, Reflected light from the document surface is reflected by the mirror and guided to the image sensor. Therefore, even in an image reading device with high productivity and capable of high-speed reading, each long light source of the document illuminator together with its reflector is large. It is possible to secure a sufficient amount of light without having to reduce the size of the original illumination device. In addition, the diffused light from each long light source is reliably collected by the reflector to significantly reduce the irradiation to areas other than the light beam irradiation area, preventing the density difference in the read image information from increasing and reproducing the original. Can be improved.

  According to the eighth aspect of the present invention, since the light beam other than the reflected light from the document surface enters the optical path of the reflected light from the document surface, the light beam shielding portion formed by the reflecting plate prevents the light beam irradiation region. It is possible to further improve the document reading reproducibility by eliminating disturbance light from other than the above.

  According to the invention described in claim 9, since the light beams from the two long light sources are respectively collected by the reflecting plate and irradiated on the document surface from both sides across the optical path of the reflected light from the document surface, By irradiating from both sides almost evenly, it is possible to cancel document shadows that are likely to occur, for example, in cut-and-paste documents.

The best mode for carrying out the present invention will be described below with reference to the drawings.
FIG. 1 shows a schematic configuration of a main part of an image reading apparatus according to the present invention. FIG. 2 is a perspective view of a long light source used in the document illumination device of the image reading apparatus.

  Reference numeral 10 in the figure denotes a support. The support 10 includes a transparent glass 12 for placing a document thereon, and two long light sources 13 are arranged in parallel in two rows in a staggered manner. The long light source 13 is a fluorescent lamp such as a xenon lamp and is an elongated cylindrical light source. For example, an aperture (opening) with an opening angle θ is formed as in the conventional example shown in FIG. The counter electrode is provided on the outer peripheral surface on both sides of the aperture. Then, as shown in FIG. 2, both ends are directly or indirectly attached to the support 10 with individual holders 14.

  A reflector 15 is provided for each long light source 13 below the long light source 13. Each of the reflectors 15 has an elliptical cross-sectional shape, and the inner end adjacent to each other is raised upward and added to them to integrally form the light shielding part 16. Then, a light path 17 of reflected light from the document surface, which will be described later, is formed between the light beam shielding portions 16 on both sides, and a light beam other than the reflected light from the document surface enters the light path 17 by the light beam shielding portion 16. Stop.

  A partition plate 18 that partitions the inside of the support 10 up and down is provided below the reflecting plates 15. A slit 19 is formed in the partition plate 18 at the position of the optical path 17. And the 1st mirror 20 is inclined and installed in the support body 10 under the slit 19 position.

  As a result, the light beams from the two long light sources 13 are collected by the elliptical reflecting plate 15 provided for each long light source 13 and placed on the transparent glass 12. A is irradiated. Then, the reflected light from the document surface A passes through the slit 19 through the optical path 17 and strikes the first mirror 20. The reflected light from the first mirror 20 passes through an imaging lens via a second mirror, a third mirror, and the like (not shown), and enters an image sensor such as a CCD sensor to read the document content as image information.

  As described above, in the illustrated image reading apparatus, the light beams from the two long light sources 13 are collected by the elliptical reflecting plate 15 to irradiate the original surface A, and the reflected light from the original surface A is reflected to the first mirror. Since the light is reflected at 20 and led to the image sensor, even in an image reading apparatus with high productivity and capable of high speed reading, the long light source 13 of the original illuminating apparatus is made up of the reflecting plate 15 by increasing the amount of original illumination. At the same time, it is not necessary to increase the size, and the document illumination device can be reduced in size. Further, the diffused light from each of the long light sources 13 is reliably condensed by the elliptical reflecting plate 15 to significantly reduce the irradiation to the area other than the light beam irradiation area B on the document surface A, and the density difference of the read image information Can be prevented and document reproducibility can be improved.

  Note that the elliptical shape of the reflecting plate 15 is such that one focal point is substantially the center of the long light source 13 and the other focal point is in the vicinity of the light beam irradiation region B. In this way, the light flux from each of the long light sources 13 is collected in the light flux irradiation area B and is not irradiated unnecessarily in areas other than the light flux irradiation area B, thereby reducing the light flux that is the source of flare light. it can.

  By the way, in the illustrated image reading apparatus, the same long light source 13 and two reflecting plates 15 are used. As a result, the same two long light sources 13 are used. For example, when any long light source 13 is replaced, it is the same. In addition, the long light source 13 can be replaced as a single unit by removing the individual holders 14, and the replacement can be facilitated to improve the maintainability.

  Then, the long light source 13 and the reflecting plate 15 are provided symmetrically on both sides of the optical path 17 of the reflected light from the document surface A, and are arranged so as to be folded. As a result, the light beams from the two long light sources 13 are collected by the reflecting plate 15 and irradiated on the document surface A from both sides with the optical path 17 of the reflected light from the document surface A interposed therebetween, so that the light beams from both sides are almost the same. By irradiating evenly, it is possible to cancel a document shadow that easily occurs, for example, in a cut-and-paste document.

  In the illustrated example, a light beam shielding member 22 that shields a portion other than the light beam irradiation area B on the document surface A is provided inside the transparent glass 12. In this case, the light beam shielding member 22 shields the area other than the light beam irradiation area B on the document surface A and prevents the light beam from the long light source 13 from irradiating the area other than the light beam irradiation area B. It is possible to effectively prevent the reflected light from entering the light beam irradiation area B, eliminate the flare and further prevent the density difference of the read image information from increasing, and further improve the document reading reproducibility.

FIG. 3 shows a schematic configuration of a main part of another image reading apparatus according to the present invention.
In the image reading apparatus shown in FIG. 3 as well, if the aperture angle of the aperture is θ, the center of the aperture is located at the angle θ / 2, and the center of the aperture is connected to the center O of the long light source 13. When the straight line is L, one focal point of each of the elliptical reflectors 15 is arranged on the straight line L at a point D that intersects the glass tube of the long light source 13 in the illustrated example. The other focal points of the reflecting plates 15 are arranged so as to be in the vicinity of the light beam irradiation area B on the document surface A.

  FIG. 4 shows a condensing state of light beams emitted from the two long light sources 13 in the image reading apparatus shown in FIG. FIG. 5 shows a condensing state of light beams emitted from the two long light sources 13 in the image reading apparatus shown in FIG. As can be seen from the comparison of these figures, the latter is more concentrated. Therefore, in the latter case, by increasing the effective luminous flux, it is possible to further increase the amount of illumination of the original and reduce the area of the reflector, thereby reducing the size of the original illumination device.

FIG. 6 shows a schematic configuration of the main part of still another image reading apparatus according to the present invention.
In this example, two long light sources 13 are provided, and as the reflecting plate 15, a first reflecting plate 15A that reflects the light beam of the long light source 13 and a light beam reflected by the first reflecting plate 15A are collected. And a second reflecting plate 15B that irradiates and irradiates the document surface A. Then, the light beams from the two long light sources 13 are reflected by the first reflecting plate 15A, condensed by the second reflecting plate 15B, and irradiated on the document surface A.

  Even in this case, since the two long light sources 13 are provided and the original surface A is irradiated with the light beams from them, the document illumination light quantity can be reduced even in an image reading apparatus with high productivity and high speed reading. The number of the long light sources 13 of the document illuminating apparatus can be increased with the reflectors 15A and 15B, and the size can be reduced.

  Further, the light beam from the long light source 13 is reflected by the first reflecting plate 15A and condensed by the second reflecting plate 15B, and only the condensed light beam guided by the second reflecting plate 15B is the original surface A. Since the direct light from the long light source 13 is not irradiated onto the document surface A, the diffused light from each long light source 13 is reliably condensed by the two reflectors and is not applied to the light beam irradiation region B. Can be greatly reduced, the density difference of the read image information can be prevented from increasing, and the document read reproducibility can be improved.

  At this time, the first reflecting plate 15A and the second reflecting plate 15B may each have an elliptical cross-sectional shape as shown in the drawing, and one of the focal points may be a common position. The first reflecting plate 15A has the other focal point as the center of the long light source 13, and the second reflecting plate 15B has the other focal point in the vicinity of the light beam irradiation region B. In this way, the light flux from each of the long light sources 13 is collected in the light flux irradiation area B so as to avoid irradiating other than the light flux irradiation area B, reducing the light flux that is the source of flare light, It is possible to further prevent the density difference of the read image information from increasing, and to further improve the document reading reproducibility.

Meanwhile, as shown in FIG. 7, taking the x-axis to the major axis direction, taking the y-axis in the minor axis, the major axis of the elliptical shape of the first reflection plate 15A and a _1, the minor axis and b _1, The elliptical shape of the first reflecting plate 15A is (x ² / a ₁ ² ) × (y ² / b ₁ ² ) = 1. Also, when the major axis of the elliptical shape of the second reflector 15B and _{a 2,} the minor and _{b 2,} oval shape of the second reflector 15B ^{_{is, (x 2 / a 2 2}} ) × (y 2 / b ₂ ² ) = 1.

At this _time, a _{a 1> b 1, a 2} > b 2, and _a 1 _<a 2 _,b 1> when to keep the relationship of _{b 2,} likewise the irradiated area the light from the elongated light source 13 It is possible to form a small document illuminating device without condensing light on B and irradiating the area other than light beam irradiation area B unnecessarily.

  The image reading apparatus according to the present invention is a method in which reading is performed by moving the document side in a state where the reading position is fixed without moving the optical system side such as the long light source 13 and the reflectors 15, 15 A, and 15 B. However, it can be applied to any method in which the original is fixed, mounted on the traveling body, scanned on the original surface while moving on the optical system side, and read.

1 is a schematic configuration diagram of a main part of an image reading apparatus according to the present invention. It is a perspective view of a long light source used in the document illumination device of the image reading device. It is a principal part schematic block diagram of another image reading apparatus by this invention. It is a figure which shows the condensing state of the light beam radiated | emitted from two elongate light sources in the image reading apparatus shown in FIG. It is a figure which shows the condensing state of the light beam radiated | emitted from two elongate light sources in the image reading apparatus shown in FIG. It is a principal part schematic block diagram of another image reading apparatus by this invention. It is an enlarged view of one side of the image reading apparatus. It is a principal part schematic block diagram of the conventional image reading apparatus. It is a longitudinal cross-sectional view of a xenon lamp used in the document illumination device of the conventional image reading device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 13 Long light source 15 Reflector 15A 1st reflector 15B 2nd reflector 16 Light beam shielding part 17 Optical path of reflected light 20 1st mirror 22 Light beam shielding member A Original surface B Light beam irradiation area D Straight line L and long light source Point that intersects the glass tube of the L L A straight line connecting the center of the long light source and the center of the aperture O Center of the long light source θ Aperture angle

Claims (9)

In the document illumination device that irradiates the surface of the document by condensing the light beam from the long light source with the reflector,
An original illuminating apparatus, wherein the two long light sources are provided, the reflecting plate is provided for each of the long light sources, and each of the reflecting plates has an elliptical shape.   One focal point of each of the elliptical reflectors is arranged on a straight line connecting the center of the long light source and the center of the aperture, and the other focal point is in the vicinity of the light beam irradiation area on the document surface. The document illumination device according to claim 1, wherein the document illumination device is disposed on the document illumination device.   3. The document illumination device according to claim 1, further comprising: a light beam shielding member that blocks a light beam from the long light source from being irradiated outside a light beam irradiation region on the document surface. In the document illumination device that irradiates the surface of the document by condensing the light beam from the long light source with the reflector,
The two long light sources are provided, and as the reflecting plate, a first reflecting plate that reflects a light beam of the long light source, and a light beam reflected by the first reflecting plate is collected to collect the original surface. An original illuminating apparatus comprising: a second reflecting plate that irradiates the top.   5. The document illuminating apparatus according to claim 4, wherein each of the first reflector and the second reflector is elliptical, and one of the focal points is arranged at a common position.   6. The document illuminating apparatus according to claim 1, wherein two same light sources are provided as the long light source.   An image reading apparatus comprising the document illumination device according to claim 1, wherein reflected light from the document surface is reflected by a mirror and guided to an image pickup device.   8. The image according to claim 7, wherein a light beam shielding portion that prevents a light beam other than the light reflected from the document surface from entering the optical path of the light reflected from the document surface is formed by the reflection plate. 9. Reader.   The image reading apparatus according to claim 7, wherein both the long light source and the reflecting plate are provided symmetrically on both sides of an optical path of reflected light from the document surface.

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