JPH02168767A - Picture reader - Google Patents

Abstract

PURPOSE:To obtain a picture with high quality and high accuracy by receiving a reflected light of picture information only being elimination of a surface reflecting light among reflected lights from an original lighted by an original light means with a picture read means and reading desired picture information. CONSTITUTION:An illuminating light L outputted from a light source 30 is collected by a reflection mirror 36 and made incident in one terminal of an optical fiber bundle 32 from a light guide member 40 via an infrared ray absorption filter 38. A reflected light R including the picture information is obtained from an original platen 22 and an adhered original 24 lighted by the light L. The reflected light R is collected on a CCD 50, in which photoelectric conversion is applied and the result becomes a picture signal. In this case, the light L is reflected by light diffusion reflecting layer 58 and radiated in an area 64 as a diffusion light having picture information and part is reflected in the surface of a surface coat layer 62 and radiated in the area 66 as a surface diffusion reflected light. A surface diffusion reflected light is not reached from the surface coat layer 62 to the picture read means 28 and only the reflected light R having the picture information is led. Thus, the CCD 50 converts the reflected light R having only the picture information into a picture signal via an image forming lens 48 to obtain a reproduced picture with high quality by using the picture signal.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an image reading device, and more particularly, an illumination means illuminates an original document carrying image information from a predetermined direction, while illuminating light reflected from the original document. The present invention relates to an image reading device configured to read light from a predetermined direction using an image reading means, thereby making it possible to remove the effects of surface reflection of a document, pasting marks on the document, and the like.

[Prior Art] For example, in the fields of printing and plate-making, image scanning, reading and reproducing is the process of electrically processing image information carried on a manuscript to create a film master plate for the purpose of streamlining work processes, improving image quality, etc. The system is widely used.

An image scanning reading and reproducing system basically consists of an image reading device and an image reproducing device.

In this case, the image reading device illuminates the document being conveyed in the sub-scanning direction using illumination means in the main scanning direction, and the image reading means reads the reflected light and converts it into an electrical signal. on the other hand,
The image reproducing device performs arithmetic processing such as gradation conversion and edge enhancement according to plate-making conditions on the image information photoelectrically converted by the image reading device, and records and reproduces the image on a record carrier such as film. Note that this recording carrier is developed by a predetermined developing device and used as a film original for printing or the like.

Incidentally, in the image reading device, a pasted original such as a photograph is often used as a manuscript stuck on a manuscript table. In this case, the illumination light causes a shadow on the peripheral edge of the pasted document based on the thickness of the document, and there is a risk that so-called pasting marks may occur in the read image.

For example, in an image reading device having the configuration shown in FIG.
While the document table 4 with the pasted original 2 pasted thereon is transported in the direction of arrow X, the surfaces of the pasted original 2 and the document table 4 are illuminated obliquely with illumination light L1 from the light source 6, and the reflected light R is illuminated from an oblique direction. C
The light is received by the CD camera 8 and converted into an electrical signal.

In this case, the pasted original 2 has a predetermined thickness, and a shaped portion 10 that is not irradiated with the illumination light L+ is generated at the peripheral edge of the pasted original 2. Therefore, the CCD camera 8
image information and the shape portion 10 are read, and a pasting mark due to the shape portion 10 is generated in the reproduced image.

Therefore, in order to erase the shaped portion 10, another light source 12 is provided at a location that is approximately symmetrical to the light source 6, and the illumination light L1 from the light source 6 and the illumination light L2 from the light source 12 are used to illuminate the pasted original. There is a device configured to erase the shaped portion 10 by illuminating the document platen 2 and document table 4.

``Problems to be Solved by the Invention'' However, in this case, there arises the disadvantage that the necessary equipment that requires the two light sources 6 and 12 becomes large and expensive. In addition, when two light sources 6 and I2 are used, the pasted original 2
Furthermore, it has been pointed out that when the position of the document table 4 changes, the illumination position a caused by the illumination lights L1 and L2 is separated, resulting in an inconvenience that the image read by the CCD camera 8 becomes uneven.

On the other hand, if the document carrying image information has surface reflection, such as photographic paper, when the surface reflection light enters the CCD camera 8, the image quality will be significantly degraded. For example, it is known that when the pasted original 2 is silk-textured photographic paper, the surface reflected light is reflected in a range of approximately ±45° with respect to the specular reflection direction of the illumination light L1. Therefore, in order to prevent the surface reflected light from entering the CCD camera 8, the illumination light L+
The angle θ formed by the reflected light R containing image information is approximately ±45°
The position of the light source 6 must be set so as to achieve the above. In this case, not only the arrangement conditions of the light source 6 are restricted, but also the angle θ between the illumination light L1 and the reflected light R increases, so the amount of reflected light R reaching the CCD camera 8 is significantly reduced. Put it away. In addition, when the two light sources 6 and 12 are used, since the angle θ is set large, the illumination light L1 when the positions of the pasted original 2 and the original platen 4 change.
The separation of the illumination position a due to , L2 becomes even more remarkable, and the unevenness of the image read by the CCD camera 8 becomes large, resulting in the inconvenience that a highly accurate image cannot be obtained.

The present invention has been made in order to overcome the above-mentioned disadvantages, and an object of the present invention is to provide an image reading device that does not receive light reflected from the surface of a document and can obtain high-quality, high-precision images. purpose.

Another object of the present invention is to provide an image reading device that can obtain high-quality, high-precision images without pasting marks of originals with a simple configuration.

[Means for Solving the Problems] In order to achieve the above object, the present invention includes a document illumination unit that guides illumination light to the document surface from a direction inclined by an illumination angle α with respect to the normal to the document surface. , an image reading means for reading reflected light including image information of the illumination light from the document surface from a direction inclined by a reading angle β with respect to the normal line, and an angle that eliminates the influence of surface reflection of the document surface. ±φ(〉
0), the illumination angle α and the reading angle β are α−φ≧
It is characterized in that it is set so that β>−90° or α+φ≦β<90°.

The present invention also provides a document illumination means for guiding illumination light to the document surface from a direction inclined by an illumination angle α with respect to the normal line of the document surface; The apparatus is characterized in that it includes an image reading means for reading reflected light including image information of the illumination light from the document surface, and the illumination angle α and the reading angle β are set so that β1>[α and αβ>0.

[Function] In the image reading device of the present invention configured as described above, the image reading means collects only the reflected light of image information from which the surface reflected light is removed from the reflected light from the original illuminated by the original illumination means. The desired image information is read from the received light.

In addition, the image reading means receives the reflected light from the original illuminated by the original illumination means other than the bulge formed at the periphery of the original by the illumination light, and uses this to detect the pasting marks on the original. No image information is read.

[Embodiments] Next, preferred embodiments of the image reading apparatus according to the present invention will be described in detail with reference to the accompanying drawings.

In FIGS. 1 and 2, reference numeral 20 indicates an image reading device according to this embodiment. In this case, the image reading device 2
Reference numeral 0 denotes an original illumination means 2 that illuminates the original table 22 that is conveyed in the sub-scanning direction in the arrow X direction and the pasted original 24 stuck on the document table 22 in the main scanning direction (arrow Z direction) with illumination light.
6, and an image reading means 28 that reads an image based on the reflected light R from the document table 22 and the pasted document 24.

The document illumination means 26 includes a point-like light source 30 such as a halogen lamp or a xenon lamp, and a number of optical fibers bundled together. The fiber bundle 32 and the illumination light are directed onto the document table 22 in the main scanning direction (arrow Z direction).
and a cylindrical lens 34 that condenses light along.

The light source 30 is surrounded by a reflecting mirror 36 formed in the shape of an ellipsoid of revolution, and the opening of the reflecting mirror 36 is coated with an infrared absorbing coating that transmits visible light and reflects infrared light. A filter 38 is provided.

Further, a light guide member 40 formed in a cylindrical shape is disposed close to the opening through an infrared absorption filter 38, and one end portion of a large number of optical fibers constituting the optical fiber bundle 32 is attached to the light guide member 40. is installed. It is preferable to use a highly flexible plastic optical fiber as the optical fiber so that the illumination light can be easily guided to a desired location on the document table 22 and the pasted document 24.

The other end of the optical fiber constituting the optical fiber bundle 32 is arranged at a predetermined distance away from the document table 22 by being curved, and the other end is connected to a long housing 42.
By storing the document in the main scanning direction of the document table 22 (arrow Z
direction) so as to form a line shape. Further, a cylindrical lens 3 is arranged between the other end of the optical fiber and the document table 22 so as to be parallel to the main scanning direction (arrow Z direction).
4 will be placed. In this case, the illumination angle between the optical axis 44 of the cylindrical lens 34 and the normal 46 erected on the document surface is α.

On the other hand, the image reading means 28 is composed of an imaging lens 48 and a CCD 50 that photoelectrically converts the reflected light R collected by the imaging lens 48 into an image signal. in this case,
Let β be the reading angle formed by the optical axis of the imaging lens 48 and the normal 46 erected on the document surface.

The image reading device according to this embodiment is basically configured as described above, and its operation and effects will be explained next.

First, the illumination light output from the light source 30 is reflected by the reflection mirror 3.
6 and enters one end of the optical fiber bundle 32 from the light guiding member 40 via the infrared absorption filter 38. Then, the illumination light is applied to the optical fiber bundle 3
After being guided to the other end of the optical fiber bundle 32 through a large number of optical fibers constituting the optical fiber bundle 2, the optical fiber bundle 32 is guided from the other end through a cylindrical lens 34 to the document table 22 and the pasted document 24 in the main scanning direction (arrow Z direction).

On the other hand, reflected light R containing image information is obtained from the document table 22 and the pasted document 24 illuminated by the illumination light.

This reflected light R is focused on the CCD 50 via the imaging lens 48, and is photoelectrically converted into an image signal. Note that since the document table 22 and the pasted document 24 are conveyed in the sub-scanning direction in the direction of the arrow X by a conveyance mechanism (not shown), image information of the entire surface thereof is read by the CCD 50.

Here, the illumination angle α and the reading angle β with respect to the pasted original 24 are
Explain the relationship between As the coordinate system, a right-handed coordinate system is selected in which the direction of the normal 46 to the document surface is Y, and the sign of the angle is set according to this coordinate system.

First, the angular relationship for eliminating the influence of surface reflection of the pasted original 24 will be explained. FIG. 3 shows a case where illumination light is incident on a pasted original 24 made of so-called silk-grain photographic paper with an uneven surface. This pasted manuscript 24
The base 56 is attached to the document table 22, and the base 56 is attached to the document table 22.
A light diffusing and reflecting layer 58 formed thereon, an emulsion layer 60 carrying image information, and a surface coating layer 6 that protects the emulsion layer 60.
It consists of 2.

In this case, the illumination light is reflected by the light diffusing and reflecting layer 58 and emitted into the region 64 as diffused light carrying image information, and a part of the illumination light is also reflected by the surface of the surface coating layer 62 as surface scattered reflected light into the region 64. It is ejected inside. Therefore, if the spread angle of the surface scattered reflected light with respect to the specularly reflected light P is ±φ (φ>0>, then in order to remove the influence of surface reflection from the reflected light R, α−φ≧β>−90° ...(1
a) Alternatively, the illumination angle α and the reading angle β may be set so that α+φ≦β<90° (1b). The reading angle β falls within the range shown by the shaded area in FIG.

In this case, the surface scattered reflected light from the surface coating layer 62 does not reach the image reading means 28, and only the reflected light R carrying image information is guided. As a result, the CCD 50 converts the reflected light R carrying only image information into an image signal via the imaging lens 48, and a high-quality reproduced image can be obtained using the image signal.

On the other hand, since the illuminance on the document surface is proportional to 1/cosα,
When the illumination angle α exceeds ±45°, it rapidly decreases. Therefore, in order to remove the influence of surface reflection, prevent illuminance reduction, and read images with high accuracy, the following conditions must be satisfied: -α-φ≧β>-90° and 45°> α...
a) Or, α+φ≦β〈90° and 45°〉1α...(2b
) The illumination angle α may be set so that

Also, when the illumination angle α and angle φ become large to a certain extent, (
The reading angle β in equations 1b) and (2b) becomes shallow relative to the document surface, which causes a problem. For example, when the original surface of the pasted original 24 moves in the Y direction, the reading position changes, or when the original surface of the pasted original 24 is held down by a platen glass, astigmatism may occur due to the thickness of the platen glass. arise. Therefore, in order to read the image with even higher precision, the conditions of equations (1b) and (2b) are deleted, and the practical range of the reading angle β is set as 45° ≧ β ... [3) -α−φ≧β≧−45° and 45°>1α...(4
) The reading angle β may be set so that in this case,
The reading angle β falls within the range shown by the shaded area in FIG.

Next, the angular relationship for removing the pasting marks on the pasted original 24 will be explained. In FIG. 6, when the pasted original 24 is illuminated at an illumination angle α, a shaped portion 54 that is not illuminated by the illumination light is generated at the periphery of the pasted original 24. In this case, the reading angle 1β) is on the illumination light side and the illumination angle 1αj
If the angle is set larger than , the image reading means 28 will not read the shaped portion 54, and therefore the pasting mark will be removed. That is, the illumination angle α and the reading angle β may be set so that β1>1α1 and αβ>0 (5). In this case, the reading angle β falls within the range shown by the shaded area in FIG.

Furthermore, in order to remove the influence of surface reflection of the pasted original 24 and pasting marks, and to read the image with high precision,
The illumination angle α and reading angle β may be set by combining the conditions of equations (4) and (5).

In this case, the reading angle β falls within the range shown by the shaded area in FIG. Note that FIGS. 1 and 2 show examples in which the illumination angle α and the reading angle β are set within such ranges.

Here, regarding the spread angle φ of the surface scattered reflected light in the two series of explanations, "TUB TIIBORY 0FTH
E PI(QTOGRAPI(ICPROCBSS)
(POIIR,T)l EDITION>.

1.977, CIIMILLAN P[I Formerly, 1sllING Co, Inc.

According to the contents described in U, S, A, P491-P493'', ±φ-±45 in the case of fine printing paper.
It has been found that the reflection density changes greatly in the range of . Therefore, when the angle φ is set to 45 degrees based on this fact, for example, when the illumination angle is set to α - -15 degrees and the reading angle is set to β = -30 degrees, the influence of surface reflection from the pasted original 24 Also, it is possible to obtain high-quality images while avoiding a decrease in the amount of reflected light. Further, the CCD 50 does not read the shaped part 54 caused by illumination light, and can obtain a high-quality image without pasting marks. Since there is no need to erase, the configuration of the image reading device 20 can be made extremely simple.

[Effects of the Invention Core As described above, according to the present invention, the document illumination means is used to illuminate the document surface at the illumination angle α, and the image reading means reads the reflected light from the document at the reading angle β. It is composed of In this case, when the angle range that can eliminate the influence of surface reflection on the document surface is 1φ to +φ, set it to -α−φ≧β>−90° or −α+φ≦β<90°. In this way, light reflected from the surface of the document that does not contain image information does not reach the image reading means, and a signal that can form an extremely high-quality image is obtained using the light reflected from the document that carries only image information. becomes possible.

Further, by setting 45°>1α (), it is possible to prevent a decrease in illuminance on the document surface and read image information with high precision.

Furthermore, by setting 45°≧1β1, it is possible to minimize reading errors due to fluctuations in the document surface.

Furthermore, by setting β>α and αβ>0, it is possible to obtain a high-quality image without reading shadows such as pasting marks that occur at the periphery of the document. In this case, there is no need to provide multiple systems of document illumination means to eliminate the shadows, and there is an advantage that the apparatus itself can be made simple and compact.

[Brief explanation of the drawing]

FIG. 1 is a schematic perspective view showing an embodiment of the image reading device according to the present invention, FIG. 2 is an explanatory side view of the image reading device shown in FIG. 1, and FIG. Figure 4, Figure 5, Figure 7, and Figure 8 are diagrams explaining the reading angle range. Figure 6 is the incident light when a pasted original is used. FIG. 9 is a diagram illustrating the structure of an image reading device as a conventional technique. 20... Image reading device 24... Pasted original 28... Image reading means 50... CCD 22... Original table 26... Original illumination means 30... Light source

Claims (3)

[Claims] (1) Document illumination means that guides illumination light to the document surface from a direction inclined by an illumination angle α with respect to the normal line of the document surface; an image reading means for reading reflected light including image information of the illumination light, and an angle for removing the influence of surface reflection of the document surface is set to ±φ(>
0), the illumination angle α and the reading angle β are set so that −α−φ≧β>−90° or −α+φ≦β<90°. (2) a document illumination means that guides illumination light to the document surface from a direction inclined by an illumination angle α with respect to the normal line of the document surface; and an image reading means for reading reflected light including image information of the illumination light, and the illumination angle α and the reading angle β are set so that |β|>|α| and αβ>0. reading device. (3) In the apparatus according to claim 2, the illumination angle α and the reading angle β are −α, with the angle for eliminating the influence of surface reflection of the document surface being ±φ (>0) with respect to the direction of specular reflection of the illumination light. An image reading device characterized in that it is set so that -φ≧β>−90° or −α+φ≦β<90°.