JP2005210338A - Image reading apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image reading apparatus capable of reducing a difference between a quantity of light made incident onto a side of an original read face end and a quantity of light made incident onto a side of an original read face center. <P>SOLUTION: The image reading apparatus 10 includes an original placing table 16 on which an original P is placed and a scanning body 28 for emitting light to the original P placed on the original placing table 16 and receiving the reflected light from the original P to read an image of the original P, and the scanning body 28 is configured to include: a light source 38 for emitting light to the original P; a first reflecting means 35 for reflecting the part of light emitted from the light source 38 and making the reflected light incident onto the original P; and a second reflecting means 39 for reflecting the part of light emitted from the light source 38 and making the reflected light incident onto the original P wherein the reflectance for the light from the vicinity of both ends of the light source 38 in its longitudinal direction is greater than the reflectance of the light from the vicinity of the middle part of the light source 38 in its longitudinal direction. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an image reading apparatus that reads a document image by irradiating a document with light from a light source and forming an image of the reflected light.

In general, in an image reading apparatus such as a scanner, a copying machine, or a facsimile, when reading a document conveyed by an automatic document feeder (ADF) or a document placed on a document placement surface on a platen glass, a light source is used. The emitted light is reflected by a reflector, and the reflected light is imaged on a line sensor such as a CCD via a mirror and a lens to read the original.
Here, when a portion having the same density (luminance) of the image of the original is read due to variations in the light distribution characteristics of the light source, insufficient light quantity on the side of the original reading surface due to the COS4 law of the lens, It is output as a signal of a different level at the main scanning position. For this reason, in the conventional image reading apparatus, the signal on the end portion side of the document reading surface is electrically amplified by the shading correction circuit to substantially the same level as the central portion side of the document reading surface.
Japanese Patent Laid-Open No. 11-142985 Japanese Patent Laid-Open No. 11-317841

  However, in shading correction, if the amount of light on the side of the document reading surface is amplified, noise is also amplified at the same time, so the so-called sensor dynamic of the line sensor on the side of the document reading surface compared to the center of the document reading surface. The problem was that the range would drop. As in recent years, when a read original becomes full of colors, reading is performed for each color, for example, with 8 bits and 256 gradations. Therefore, if the sensor dynamic range is reduced, the same density (luminance) of the original image is obtained. There arises a problem that color misregistration occurs between the central portion side of the original reading surface and the end portion side of the original reading surface.

  In view of the above circumstances, the present invention provides an image reading apparatus capable of reducing the difference between the amount of light incident on the end of the document reading surface and the amount of light incident on the center of the document reading surface. Objective.

  According to a first aspect of the present invention, there is provided a document placement table on which a document is placed, and an image of the document by irradiating light on the document placed on the document placement table and receiving reflected light from the document. A scanning body that scans the document, and the scanning body includes a light source that irradiates the original with light, and a part of the light emitted from the light source that reflects and enters the original. 1 reflecting means and a part of the light emitted from the light source is reflected and incident on the original so that the light reflectance from the vicinity of both ends in the longitudinal direction of the light source is light from the vicinity of the central portion in the longitudinal direction of the light source. The second reflecting means is larger than the reflectance of the second reflecting means.

According to the first aspect of the present invention, light is emitted from the light source of the scanning body toward the document placed on the document placing table, and the light reflected by the document is received to read the image of the document.
Here, a part of the light emitted from the light source is reflected toward the original by the first reflecting means and the second reflecting means, respectively, but the second reflecting means reflects light from the vicinity of both ends in the longitudinal direction of the light source. The ratio of light reflected from both ends in the longitudinal direction of the light source is near the center in the longitudinal direction of the light source. It becomes larger than the amount of reflected light from As a result, even if the amount of light at the edge of the original reading surface is insufficient due to variations in the light distribution characteristics of the light source or the COS4 power law of the condenser lens, the amount of reflected light from the vicinity of both ends in the longitudinal direction of the light source increases. The amount of light in the vicinity of both ends in the longitudinal direction of the light source can be increased. As a result, it is possible to reduce the difference between the light amount in the vicinity of both ends in the longitudinal direction of the light source and the light amount in the vicinity of the central portion in the longitudinal direction of the light source, and the light amount distribution of the light incident on the image reading range of the document can be made closer to uniform. Therefore, the image reading quality can be improved.
In particular, a part of the light from the light source is reflected by the first reflecting means and the reflected light is incident on the original, and a part of the light from the light source is reflected by the second reflecting means and the reflected light is reflected on the original. By making the light incident, the amount of light applied to the original can be remarkably increased by these synergistic effects. As a result, the image quality of the original can be further improved.

  According to a second aspect of the present invention, in the image reading apparatus according to the first aspect, the second reflecting means has a reflection area where the light is reflected as it approaches the both longitudinal ends from the longitudinal central portion of the light source. It is configured to be large.

  According to the second aspect of the present invention, the second reflecting means is configured such that the reflection area where the light is reflected increases as it approaches the both longitudinal ends from the longitudinal center of the light source. The amount of reflected light from the vicinity of both ends in the longitudinal direction can be increased. Thus, the light quantity in the vicinity of both ends in the longitudinal direction of the light source can be increased with a simple configuration.

  According to a third aspect of the present invention, in the image reading apparatus according to the first or second aspect, the front first reflecting means is provided at a portion facing the document placing table, and the second reflecting means is inclined. It is provided in the site | part which is carrying out.

According to the third aspect of the present invention, since the first reflecting means is provided at a portion facing the document placing table, the light reflected by the first reflecting means can be effectively incident on the document. . Further, since the second reflecting means is provided at the inclined portion, the light reflected by the second reflecting means can be effectively incident on the document.
As a result, the amount of light applied to the document increases, and the image reading quality can be further improved.

  According to a fourth aspect of the present invention, in the image reading apparatus according to any one of the first to third aspects, the second reflecting means is a white tape-shaped member formed integrally or a white tape-like member. It is characterized by being configured by applying a paint.

  According to the fourth aspect of the present invention, the second reflecting means is configured by attaching the white tape-shaped member integrally formed or applying the white paint, thereby reducing the second reflecting means. It can be provided easily and cost-effectively. Further, the white color can increase the reflectance of light, and the amount of light incident on the document can be increased.

According to the first aspect of the present invention, it is possible to reduce the difference between the light amount in the vicinity of both ends in the longitudinal direction of the light source and the light amount in the vicinity of the central portion in the longitudinal direction of the light source, and the light amount distribution of the light incident on the image reading range of the document. Therefore, it is possible to improve the image reading quality.
In particular, a part of the light from the light source is reflected by the first reflecting means and the reflected light is incident on the original, and a part of the light from the light source is reflected by the second reflecting means and the reflected light is reflected on the original. By making the light incident, the amount of light applied to the original can be remarkably increased by these synergistic effects. As a result, the image quality of the original can be further improved.

  According to the second aspect of the present invention, the second reflecting means is configured such that the reflection area where the light is reflected increases from the central portion in the longitudinal direction of the light source toward the both ends in the longitudinal direction. The amount of reflected light from the vicinity of both ends can be increased. Thus, the light quantity in the vicinity of both ends in the longitudinal direction of the light source can be increased with a simple configuration.

According to the third aspect of the present invention, since the first reflecting means is provided at a portion facing the document placing table, the light reflected by the first reflecting means can be effectively incident on the document. Further, since the second reflecting means is provided at the inclined portion, the light reflected by the second reflecting means can be effectively incident on the document.
As a result, the amount of light applied to the document increases, and the image reading quality can be further improved.

  According to a fourth aspect of the present invention, the second reflecting means is constructed by attaching an integrally formed white tape-like member or applying a white paint, thereby reducing the cost of the second reflecting means. It can be provided simply. Further, the white color can increase the reflectance of light, and the amount of light incident on the document can be increased.

  Next, an image reading apparatus according to an embodiment of the present invention will be described with reference to the drawings.

  As shown in FIG. 1, the image reading apparatus 10 includes a box-shaped housing 12 whose upper surface is open. A platen glass 16 (original placement table) made of transparent glass is disposed on the upper surface 14 of the housing 12. In the interior 18 of the housing 12, a guide shaft 20 for guiding the document reading unit 26 and a guide rail 24 having a sliding plane 22 on the upper surface of the document reading unit 26 on the platen glass 16 are provided. Are arranged in parallel.

  As shown in FIG. 2, the document reading unit 26 includes a scanning body 28. The scanning body 28 includes a scanning body main body 29 that is integrally molded with a black resin, a light source case 31 that is integrally molded with a black resin and is attached to an upper portion of the scanning body 28 (on the platen glass 16 side), and a light source case 31. A tubular light source 38 for irradiating light to the original P placed on the platen glass 16 and a first mirror provided inside the scanning body 29 for guiding reflected light from the original P to the CCD base 54. 42, the second mirror 44, the third mirror 46, the fourth mirror 48, and the reflected light guided by the first to fourth mirrors 42, 44, 46, 48 provided inside the scanning body 29. The lens 50 is made to illuminate, and the CCD substrate 54 is provided in the scanning body 29 and receives light from the lens 50 and converts an optical signal into an electric signal. The description of each component will be described later.

Here, as shown in FIGS. 2 and 3, the first inclined surface 33 of the light source case 31 located on the back surface portion (the portion facing the platen glass 16) of the light source 38 has a longitudinal direction of the light source 38 (FIG. 3). A white first reflection seal (first reflection means) 35 integrally formed over the middle arrow A direction is attached (shaded portion in FIG. 3). The first reflective seal 35 is formed so that the reflection area from which light is reflected increases from the longitudinal center of the light source 38 to both longitudinal ends. That is, light emitted from the vicinity of both ends in the longitudinal direction of the light source 38 is reflected by a portion having a relatively large reflection area of the first reflection seal 35, and light emitted from the vicinity of the central portion in the longitudinal direction of the light source 38 is first reflected. The seal 35 is reflected at a portion having a relatively small reflection area. As a result, the amount of reflected light emitted from the vicinity of both ends in the longitudinal direction of the light source 38 becomes larger than the amount of reflected light emitted from the vicinity of the central portion of the light source 38 in the longitudinal direction. Note that light is not easily reflected by the black resin portion of the light source 38, and the light transmittance is increased.
In particular, since the back surface portion is configured to have an inclined surface at a portion facing the platen glass 16, the light reflected by the first reflective seal 35 can be effectively incident on the original P.

Further, as shown in FIGS. 2 to 4, the second inclined surface inclined upward toward the upper side of the light source case 31 on the opposite side through the first inclined surface 33 and the slit (described later) 34 of the light source case 31. 37 is formed, and a white second reflective seal (second reflective means) 39 integrally formed over the longitudinal direction of the light source 38 (the direction of arrow A in FIG. 3) is attached to the second inclined surface 37. (Shaded area in FIG. 3). The second reflective seal 39 is formed so that the reflection area from which light is reflected increases from the longitudinal center of the light source 38 to both longitudinal ends. That is, the light emitted from the vicinity of both ends in the longitudinal direction of the light source 38 is reflected by a portion having a relatively large reflection area of the second reflection seal 39, and the light emitted from the vicinity of the central portion in the longitudinal direction of the light source 38 is second reflected. The seal 39 is reflected by a portion having a relatively small reflection area. As a result, the amount of reflected light emitted from the vicinity of both ends in the longitudinal direction of the light source 38 becomes larger than the amount of reflected light emitted from the vicinity of the central portion of the light source 38 in the longitudinal direction.
In particular, since the second inclined surface 37 is inclined, the light reflected by the second reflection seal 39 can be effectively incident on the original P.

Since the first reflective seal 35 and the second reflective seal 39 are integrally formed, the first reflective seal 35 and the second reflective seal 39 can be easily attached to the first inclined surface 33 and the second inclined surface 37 with one touch. Although it is convenient in terms of management of the 35 and the second reflective seal 39, it is not limited to an integrally formed configuration, and a plurality of separate white first reflective seals and second reflective seals are arranged on the first inclined surface. The structure which affixed on 33 and the 2nd inclined surface 37, respectively may be sufficient.
Further, the first reflecting means and the second reflecting means are not limited to the first reflecting seal 35 and the second reflecting seal 39, and may be white tape, and the first inclined surface 33 and the second inclined surface 37 may be provided. A configuration in which a white paint is directly applied may be used.
Furthermore, by making the first reflective seal 35, the second reflective seal 39, and the paint white, the reflectance of light can be improved and the amount of reflected light can be increased, but it is not limited to white, and light is reflected. Other bright colors may be used.
In addition, it is not restricted to the 1st reflective seal 35, the 2nd reflective seal 39, and coating, The structure which provided the member which has a mirror surface in the 1st inclined surface 33 and the 2nd inclined surface 37, respectively, and reflects light in a mirror surface It may be.

Further, as shown in FIGS. 1 to 3, the scanning body 28 is disposed so as to extend in a direction perpendicular to the scanning direction (arrow X direction side in FIGS. 1 to 3). A guide shaft 20 penetrates in the vicinity of one end of the scanning body 28 in the width direction. Further, the bottom 32 near the other end in the width direction of the scanning body 28 is brought into contact with the sliding plane 22 of the guide rail 24 so as to be movable in the scanning direction (arrow X direction side in FIGS. 1 to 3). ing.
As a result, the scanning body 28 can move in the scanning direction (in the direction of arrow X in FIGS. 1 and 2) in a state parallel to the platen glass 16.

  As shown in FIGS. 2 to 4, a light source case 31 is provided on the opened upper surface of the scanning body 29. In the light source case 31, a slit 34 for guiding the reflected light from the document P to the inside of the scanning body 29 is formed in the width direction of the light source case 31. Further, a tubular light source 38 extending in parallel with the longitudinal direction of the scanning body 28 is disposed in the vicinity of the slit 34. Further, a first mirror 42, a second mirror 44, a third mirror 46, and a fourth mirror 48 for guiding light reflected from the original P to a lens 50 described later are provided inside the scanning body 29, respectively. Yes. A lens 50 for condensing the light reflected by each of the first mirror 42, the second mirror 44, the third mirror 46, and the fourth mirror 48 is provided on the optical path L of the reflected light from the document P. ing. A CCD base 54 is provided on one side wall 52 of the scanning body main body 29 extending in a direction perpendicular to the returning direction of the scanning body 28 (arrow Y direction side in FIG. 3).

As shown in FIG. 1, a stepping motor 64 as a drive source for reciprocating the scanning body 28 is disposed in the vicinity of one end portion of the guide shaft 20 inside the housing 18. A driving shaft 66 for transmitting a driving force is connected to the stepping motor 64. A pulley 68 is fixed to the drive shaft 66.
A non-driving pulley 70 is rotatably disposed near the other end of the guide shaft 20. Further, a belt 74 is wound around the pulley 68 to which the driving force is transmitted and the non-driving pulley 70. The scanning body 28 is fixed to a part of the belt 74.

  Next, the operation of the image reading apparatus 10 of this embodiment will be described.

  As shown in FIGS. 1 to 3, when reading the image of the document P, light is emitted from the light source 38. At this time, the light emitted from the light source 38 propagates radially, and a part of the light directly enters the original P. Further, part of the light emitted from the light source 38 is reflected by the first reflection seal 35, and the reflected light enters the original P.

  Here, since the first reflective seal 35 is formed so that the reflection area from which light is reflected increases from the longitudinal center of the light source 38 to both ends in the longitudinal direction, it is emitted from the vicinity of both ends in the longitudinal direction of the light source 38. The reflected light amount of the emitted light is larger than the reflected light amount of the light emitted from the vicinity of the central portion in the longitudinal direction of the light source 38. As a result, even if the amount of light at the end of the original reading surface is insufficient due to variations in the light distribution characteristics of the light source 38 or the COS 4 law of the lens 50, the amount of reflected light from the vicinity of both ends in the longitudinal direction of the light source 38 increases. The amount of light in the vicinity of both ends in the longitudinal direction of the light source 38 can be increased. As a result, it is possible to reduce the difference between the light amount in the vicinity of both ends in the longitudinal direction of the light source 38 and the light amount in the vicinity of the central portion in the longitudinal direction of the light source 38, and the central portion of the image reading range of the original P (original portion of the original reading surface) It is possible to reduce the difference between the amount of light incident on the light and the amount of light incident on the end (document reading surface end).

Further, part of the light emitted from the light source 38 is reflected by the second reflection seal 39, and the reflected light enters the original P.
Here, since the second reflective seal 39 is formed so as to increase the reflection area where light is reflected from the longitudinal center of the light source 38 to both ends in the longitudinal direction, the second reflective seal 39 emits light from the vicinity of both ends of the light source 38 in the longitudinal direction. The reflected light amount of the emitted light is larger than the reflected light amount of the light emitted from the vicinity of the central portion in the longitudinal direction of the light source 38. As a result, even if the amount of light at the end of the original reading surface is insufficient due to variations in the light distribution characteristics of the light source 38 or the COS 4 law of the lens 50, the amount of reflected light from the vicinity of both ends in the longitudinal direction of the light source 38 increases. The amount of light in the vicinity of both ends in the longitudinal direction of the light source 38 can be increased. As a result, it is possible to reduce the difference between the light amount in the vicinity of both ends in the longitudinal direction of the light source 38 and the light amount in the vicinity of the central portion in the longitudinal direction of the light source 38, and the central portion of the image reading range of the original P (original portion of the original reading surface) It is possible to reduce the difference between the amount of light incident on the light and the amount of light incident on the end portion (end portion of the original reading surface).
In particular, since the amount of light is supplemented by the amount of light reflected by the second reflective seal 39, the amount of light incident on the original P can be increased as a whole by a synergistic effect, and the amount of light near both ends in the longitudinal direction of the light source 38 can be increased. The difference between the light amount in the vicinity of the central portion in the longitudinal direction of the light source 38 can be further reduced, and the light amount and the end (original reading surface) of the light incident on the central portion (original portion of the original reading surface) of the image reading range of the original P. The difference from the amount of light incident on the end portion can be further reduced.

Further, the light reflected by the document P enters the scanning body 28 through the slit 34 of the scanning body 28. Further, the reflected light that has entered the scanning body 28 is sequentially reflected by the first mirror 42, the second mirror 44, the third mirror 46, and the fourth mirror 48, and collected by the lens 50. The reflected light collected by the lens 50 enters the CCD base 54, and the optical signal is converted into an electrical signal in the CCD base 54. As a result, the image of the original P is read.
Here, by reducing the difference between the amount of light incident on the center of the image reading range of the document P (the center of the document reading surface) and the amount of light incident on the end (the end of the document reading surface), Since the difference between the amount of reflected light reflected from the center of the document reading surface of the document P and the amount of reflected light reflected from the edge of the document reading surface can be reduced, the amount of image light transmitted through the center of the lens 50 can be reduced. The difference from the amount of image light transmitted through the end of the lens 50 can be reduced. As a result, there is no great variation in the amount of light incident on the CCD substrate 54, so that the image reading quality of the original P can be improved.
In particular, in the image reading apparatus 10 of the present embodiment, the amount of light incident on the document P is supplemented by the second reflection seal 39, and therefore, the amount of image light transmitted through the center of the lens 50 and the end of the lens 50 are increased due to a synergistic effect. The difference from the amount of image light transmitted through the portion can be further reduced, and the image reading quality of the original P can be significantly improved.

  Further, even when shading correction is performed by the shading correction circuit, noise amplification is prevented as much as possible by further reducing the difference between the light amount in the vicinity of both ends in the longitudinal direction of the light source 38 and the light amount in the vicinity of the central portion of the light source 38 in the longitudinal direction. be able to. As a result, the so-called dynamic range of the CCD base 54 at the edge of the original reading surface can be prevented from being lowered as much as possible. As a result, when a color original P including each color is read with, for example, 8 bits and 256 gradations, the portion of the original P having the same density (luminance) is between the central portion of the original reading surface and the end of the original reading surface. It is possible to prevent color misregistration as much as possible.

  In the image reading apparatus 10 of the present embodiment, the first reflective seal 35 and the second reflective seal 39 are configured such that the light reflection area increases as the shape of the first reflective seal 35 and the second reflective seal 39 approaches the both longitudinal ends from the central portion in the longitudinal direction of the light source 38. However, the present invention is not limited to this. For example, the first inclined surface 33 and the second inclined surface 37 at the center in the longitudinal direction of the light source 38 are made of a material having low light reflectivity, and the longitudinal direction of the light source 38 For example, the first inclined surface 33 and the second inclined surface 37 at both ends are made of a material that increases the reflectance of light. You may make it change suitably.

1 is a schematic configuration diagram of an image reading apparatus according to an embodiment of the present invention. It is a schematic block diagram of the scanning body used for the image reading apparatus which concerns on one Embodiment of this invention. It is a top view of the scanning body used for the image reading apparatus which concerns on one Embodiment of this invention. It is a perspective view of the light source case which comprises the scanning body used for the image reading apparatus which concerns on one Embodiment of this invention.

Explanation of symbols

10 Image Reading Device 16 Platen Glass (Document Placement Table)
28 Scanning body 38 Light source 35 First reflection seal (first reflection means, tape-shaped member)
39 Second reflective seal (second reflective means, tape-shaped member)

Claims (4)

An image having a document placement table on which a document is placed, and a scanning body that irradiates light on the document placed on the document placement table, receives light reflected from the document, and reads an image of the document. A reading device,
The scanning body includes a light source for irradiating the original with light, first reflecting means for reflecting a part of the light emitted from the light source and entering the original, and a part of the light emitted from the light source. A second reflecting means that reflects the light and enters the original so that the reflectance of light from the vicinity of both ends in the longitudinal direction of the light source is larger than the reflectance of light from the vicinity of the central portion in the longitudinal direction of the light source; An image reading apparatus comprising:   2. The image according to claim 1, wherein the second reflecting unit is configured such that a reflection area where the light is reflected increases as the distance from the longitudinal central portion of the light source approaches both longitudinal ends. Reader. The first reflecting means is provided at a portion facing the document placing table,
The image reading apparatus according to claim 1, wherein the second reflecting unit is provided at an inclined portion.   The said 2nd reflection means is formed by affixing the white tape-shaped member formed integrally, or apply | coating a white coating material, The structure of any one of Claim 1 thru | or 3 characterized by the above-mentioned. Image reading device.

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