JP2000111495A - Image input device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image input device which obtains image data by a method wherein the surface of a transferred flat object or the like is imaged in an extremely restricted narrow imaging space. SOLUTION: In this image input device, a main scanning operation by a line sensor camera 1 is combined with a subscanning operation by the transfer of an object 11 to be imaged, the object 11 to be imaged is imaged, and image data is obtained. In the image input device, the line sensor camera 1 is provided, a linear light source 2 is provided, and an optical-axis conversion means is provided. The line sensor camera 1 images the linear imaging region of the object 11, to be imaged, via the optical-axis conversion means. The optical-axis conversion means makes the line sensor camera 1 agree with the optical axis of the linear light source 2 on the side of the object 11 to be imaged, and it separates the line sensor camera 1 from the optical axis on its opposite side.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention belongs to the technical field of an image input device. In particular, the present invention relates to an image input device that obtains image data by imaging a surface of a flat article or the like to be transferred in a very limited narrow imaging space.

[0002]

2. Description of the Related Art In order to inspect the appearance of an article processed by a processing apparatus, image data is obtained by imaging the surface of the article. For example, the inspection of the printing surface of the printed cardboard paper, the inspection of the printed surface of a small piece of printed matter (carton blank) obtained by punching the paperboard paper, and the like are performed. At this time, it is desirable to inspect the processed inspection target article in the processing apparatus so that the occurrence of the defect can be dealt with immediately.

FIG. 7 shows a configuration of a conventional image input device.
In FIG. 7, reference numeral 101 denotes a line sensor camera;
a and 102b are linear light sources; 103a and 103b are reflecting mirrors; 111 is an inspection object; 121a and 121b are transport belts; 122a and 122b are transport belt rollers;
3, 124, 125, and 126 are pressing rollers. As shown in FIG. 7, the flat inspection target article 111 is transported by the transport belts 121a and 121b of the transport unit of the processing apparatus. Holding rollers 123, 124, 125,
Reference numeral 126 denotes the conveyance belt 121a, 1
21b to fix the posture of the inspection target article 111 during conveyance. The transport unit is transport belt 1
21a and a transport belt 121b. At these connection portions, there are slight linear (slit-shaped) gaps through which the inspection object 111 can be viewed.

[0004]

In many processing apparatuses, it is difficult to secure a sufficiently large imaging space at a position suitable for imaging. In many processing equipment,
As shown in FIG. 7, the transport belt 121a and the transport belt 1
The connection portion with 21b is the only position suitable for imaging. In order to capture an image in a small slit-like gap at the connection portion, a line sensor camera 101 is suitable as an imaging unit. However, as shown in FIG. 7, the illumination means of the conventional image input device includes linear light sources 102a and 102b arranged on both sides of a linear imaging region. According to the configuration of the illumination unit, the illumination light does not sufficiently reach the linear imaging region of the inspection target article 111 as a shadow of the transport belt 121a and the transport belt 121b, and thus the imaging cannot be performed.

It is an object of the present invention to provide an image input apparatus which obtains image data by picking up an image of a surface of a flat article or the like to be conveyed in a very limited narrow imaging space.

[0006]

The above objects are achieved by the present invention described below. That is, the image input device according to the first embodiment of the present invention is an image input device that obtains image data by imaging the article to be imaged by combining main scanning by a line sensor camera and sub-scanning by transporting the article to be imaged. There is a line sensor camera, a linear light source and an optical axis conversion means, the line sensor camera images the linear imaging area of the imaging target article via the optical axis conversion means,
The linear light source irradiates light to the linear imaging region via the optical axis conversion unit, and the optical axis conversion unit sets the optical axis of the line sensor camera and the linear light source on the side of the imaging target article. They are matched and separated on the opposite side.

According to the present invention, a line sensor camera captures an image of a linear imaging area of an article to be imaged via an optical axis conversion means, and a linear light source captures a linear image of the article to be imaged via the optical axis conversion means. The area is irradiated with light, and the optical axis converting means causes the optical axes of the line sensor camera and the linear light source to coincide on the side of the article to be imaged and to be separated on the opposite side. That is, since the optical axis coincides with the optical axis of the line sensor camera on the side of the object to be imaged, the light emitted by the linear light source passes through a small gap and irradiates the linear imaging area. Therefore, there is provided an image input apparatus which obtains image data by imaging a surface of a flat article or the like to be transferred in a very limited narrow imaging space.

According to a second aspect of the present invention, there is provided an image input apparatus according to the first aspect, wherein a light diffusing means is provided between the linear light source and the optical axis converting means. . According to the present invention, the ratio of the specularly reflected light that reaches the line sensor camera after being specularly reflected on the surface of the object to be imaged in the irradiation light of the linear light source can be adjusted by the light diffusion unit. Therefore, when the surface of the object to be imaged has an optical characteristic of performing extremely regular reflection and regular reflection, such as a printed material subjected to an OP (overprint) process, harmful regular reflection light that hinders imaging is reduced. be able to. An image input device according to a third embodiment of the present invention is the image input device according to the first embodiment, further including a light condensing unit between the linear light source and the optical axis conversion unit. . ADVANTAGE OF THE INVENTION According to this invention, the radiation of the linear light source which has light diffusivity can be condensed and the surface of the imaging target article can be irradiated effectively.

According to a fourth aspect of the present invention, in the image input apparatus of any one of the first to third aspects, the optical axis conversion means is a half mirror. ADVANTAGE OF THE INVENTION According to this invention, the path | route of the light beam of a linear light source and the path | route of the light beam which a line sensor camera receives can be made to correspond very much by a half mirror, and it irradiates a linear imaging area through an extremely narrow clearance. Can be. An image input device according to a fifth aspect of the present invention is the image input device according to any one of the first to third aspects, wherein the optical axis conversion means is a mirror having a slit. According to the present invention, the path of the light beam passing through the slit is different from the path of the light beam reflected by the mirror. Therefore, the path of the light beam of the linear light source and the path of the light beam received by the line sensor camera can be separated from each other, and harmful regular reflection light that hinders imaging can be reduced. The image input device according to the seventh aspect of the present invention includes
In the image input device of any one of the sixth to sixth aspects, an optical axis of the line sensor camera is not parallel to a normal to a surface of the linear imaging region of the imaging target article. According to the present invention, it is possible to reduce harmful regular reflected light that hinders imaging.

[0010]

Next, the present invention will be described with reference to embodiments. FIG. 1 shows an example (Example 1) of the configuration of the image input device of the present invention. In FIG. 1, 1 is a line sensor camera, 2 is a linear light source, 3 is a half mirror, 11 is an inspection object, 21a and 21b are transport belts, 22a and 2
2b is a belt roller, and 23, 24, 25 and 26 are pressing rollers. As shown in FIG. 1, the flat article 11 to be inspected is transported by a transport belt 21a, 21
1b. Belt rollers 22a, 22b
Is a guide roller or a driving roller for reversing the transport direction to circulate the transport belts 21a and 21b along a predetermined path. Pressing rollers 23, 24, 25, 26
Presses the inspection object 11 against the conveyor belts 21a and 21b to fix the posture of the inspection object 11 during the transportation. Also, the pressing rollers 23, 24, 25, 26
Accordingly, the imaging distance between the inspection target article 11 and the line sensor camera 1 is maintained at a predetermined distance.

The transport unit has two components, a transport belt 21a and a transport belt 21b. At these connection portions, there are slight linear (slit-shaped) gaps through which the inspection object 11 can be viewed. In many processing apparatuses, it is difficult to secure a sufficiently large imaging space at a position suitable for imaging. In many processing apparatuses, as shown in FIG. 1, the connection between the conveyor belt 21a and the conveyor belt 21b is the only position suitable for imaging.

As the light receiving element, for example, a linear array of C
A line sensor camera 1 using a CD (charge coupled device) sensor is suitable as an image pickup means for picking up an image in a small slit-like gap at the connection portion. The line sensor camera 1 does not have a two-dimensional imaging region but has a linear imaging region. Assuming that the image data is data in which pixel data is arranged in a matrix, one line of pixel data is obtained each time the line sensor camera 1 captures an image of the linear imaging region. Imaging target article 1
1 is continuously moving, and each time the line sensor camera 1 performs imaging, when the imaging target article 11 moves in the column direction and the portion of the imaging target article 11 located in the linear imaging area changes, the pixel data Are arranged in a matrix, that is, image data can be obtained. An image of the imaging target article 11 is taken by combining the main scanning by the line sensor camera 1 and the sub-scanning by transporting the imaging target article 11 by the transport unit.

The image signal output from the line sensor camera 1 is usually an analog signal. This imaging signal is converted into a digital signal by an A / D converter (analog-to-digital converter). Normally, the A / D converter is configured to perform sampling on a pixel basis (or on a light receiving element basis). Therefore, each sampled data of the obtained time-series digital signal is pixel data. The pixel data is input and stored by the storage means. Imaging target article 11
When the predetermined main scanning and sub-scanning for are completed, the image input of the imaging target article 11 is also completed. The predetermined set of pixel data is stored as image data in the image data storage unit.

The linear light source 2 is a light source that emits light linearly. Specifically, the linear light source 2 is, for example, a straight tube discharge arc tube such as a high-frequency lighting fluorescent lamp or a pulse-driven xenon lamp. The linear light source 2 is, for example, a linear light source formed by combining a point light source such as a halogen lamp and a metal halide lamp with a light guide or an optical fiber to form a linear luminous body. Linear light source 2
Is, for example, a linear light source in which LEDs (light emitting diodes) are linearly arranged.

As shown in FIG. 1, light emitted from the linear light source 2 reaches the half mirror 3, and a part of the light is reflected by the half mirror 3 to illuminate the article 11 to be imaged. An object (not shown) that partially transmits the half mirror 3 and absorbs light
Absorbed and extinguished. Part of the light reflected on the linear imaging region of the imaging target article 11 reaches the half mirror 3 and part of the light passes through the half mirror 3 and reaches the light receiving lens of the line sensor camera 1. In other words, the line sensor camera 1 captures an image of the linear imaging area of the imaging target article 11 by the light transmitted through the half mirror 3.

The half mirror 3 is an optical axis conversion means. That is, the half mirror 3 makes the optical axes of the line sensor camera 1 and the linear light source 2 coincide with each other on the side of the article to be imaged and separates them on the opposite side. That is, FIG.
As shown in (2), the optical axis coincides with the optical axis of the line sensor camera on the side of the object to be imaged. Of course, the light rays, which are the trajectories of the light, are dispersed around the optical axis. However, in the configuration shown in FIG. 1, for example, by optimizing the dimensions of the half mirror 3, the main light rays can be collected around the optical axis. And is efficiently radiated to the linear imaging region. Therefore, image data can be obtained by imaging the surface of a flat article or the like to be transferred in a very limited narrow imaging space.

Next, an example (example 2) of the configuration of the image input device of the present invention is shown in FIG. 2, the same parts as those in FIG. 1 are denoted by the same reference numerals. The same applies to the subsequent figures (FIGS. 3 to 6). The difference between FIG. 1 and FIG. 2 is that a light diffusion plate 4 is provided between the linear light source 2 and the half mirror 3. The description of the same parts will be omitted, and different points will be described. In the case where the light emitted from the linear light source 2 is a beam having sharp directivity such that the light emitted from the linear light source 2 is concentrated on the optical axis, the imaging target article 1
The light that is specularly reflected on the surface of No. 1 becomes strong. The specularly reflected light is modulated by a pattern printed on the imaging target article 11 and is not light including the pattern information but the imaging target article 1.
1 depends only on the reflection characteristics of the surface. For example, when the surface of the object 11 to be imaged has an extremely smooth and optical characteristic of performing regular reflection, such as a printed matter subjected to an OP (overprint) process for giving gloss to the surface, the regular reflection light is extremely large. Become stronger. This specularly reflected light is harmful light that hinders image capturing when image information of the image capturing target article 11 is to be obtained by image capturing.

The light diffusing plate 4 diffuses light when the light (light flux) emitted from the linear light source 2 is concentrated on the optical axis, and emits light from a wide area determined by the dimensions of the light diffusing plate 4 and the like. Has the same effect as The light diffusing plate 4 can adjust the proportion of the regular reflection light that reaches the line sensor camera after being regularly reflected on the surface of the object to be imaged in the irradiation light of the linear light source 2. Therefore, when the surface of the imaging target article 11 has an optical characteristic of regular reflection, harmful regular reflection light that hinders imaging can be reduced.

Next, an example (Example 3) of the configuration of the image input apparatus of the present invention is shown in FIG. The difference between FIG. 1 and FIG. 3 is that a lens 5 is provided between the linear light source 2 and the half mirror 3. The description of the same parts will be omitted, and different points will be described. Conversely to the case of FIG. 2, when the radiation light of the linear light source 2 has a light diffusing property, the radiation light reaches the surface of the linear imaging region of the imaging target article 11 in the radiation light and contributes to illumination. The rate of doing so is small. By providing a lens 5 for condensing light between the linear light source 2 and the half mirror 3, the radiation light of the linear light source 2 having light diffusivity is condensed and the surface of the imaging target article 11 is efficiently illuminated. Can be irradiated. Similar effects can be obtained by providing a light reflecting plate behind the linear light source 2 instead of the lens 5. Needless to say, a greater effect can be obtained by using the lens 5 and the light reflecting plate together.

Next, FIG. 4 shows an example (Example 4) of the configuration of the image input apparatus of the present invention. The difference between FIG. 1 to FIG. 3 and FIG.
The point is that a mirror with a slit is provided instead of the half mirror 3 as the optical axis converting means. The description of the same parts will be omitted, and different points will be described. By using a mirror with a slit instead of the half mirror 3, the path of the light beam passing through the slit and the path of the light beam reflected by the mirror are different. Light rays passing through the slit out of the light emitted from the linear light source 2 are absorbed by the light absorber 7 and disappear. The light reflected by the mirror in the light emitted from the linear light source 2 is reflected from the optical axis imaged by the line sensor camera 1.
It has an angle greater than or equal to a predetermined value. Therefore, the path of the light beam of the linear light source and the path of the light beam received by the line sensor camera can be separated from each other, and harmful regular reflection light that hinders imaging can be reduced.

Next, an example (example 5) of the configuration of the image input apparatus of the present invention is shown in FIG. The difference from FIGS. 1 to 5 is that the optical axis of the line sensor camera 1 is non-parallel (has an angle) to the normal to the surface of the linear imaging region of the imaging target article 11. The description of the same parts will be omitted, and different points will be described. As shown in FIG. 6, by setting the optical axis of the line sensor camera 1 to be non-parallel to the normal of the surface of the linear imaging region of the imaging target article 11, harmful regular reflection light that hinders imaging is generated. Can be reduced. In FIG. 6, the guide roller 27 is provided in the transport unit. However, it is needless to say that the linear imaging area can be secured by avoiding the guide roller 27 by observing at an angle in this manner.

[0022]

As described above, according to the present invention, there is provided an image input apparatus for obtaining image data by imaging the surface of a flat article or the like to be conveyed in a very limited narrow imaging space. Further, according to the image input device of the second aspect of the present invention, when the surface of an object to be imaged has an optical characteristic of performing extremely regular reflection and regular reflection, such as a printed material subjected to an OP (overprint) process, In addition, it is possible to reduce harmful regular reflection light that hinders imaging. The third aspect of the present invention
According to the image input device of the above aspect, it is possible to collect the radiation light of the linear light source having light diffusing property and to irradiate the surface of the imaging target article effectively. Further, according to the image input device of the fourth aspect of the present invention, it is possible to irradiate a linear imaging area through an extremely narrow gap. Further, according to the image input device of the fifth aspect of the present invention, the path of the light beam of the linear light source and the path of the light beam received by the line sensor camera can be separated from each other, and harmful regular reflection light that hinders imaging can be obtained. Can be reduced. According to the image input device of the sixth aspect of the present invention,
It is possible to reduce harmful regular reflection light that hinders imaging.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example (Example 1) of a configuration of an image input device of the present invention.

FIG. 2 is a diagram illustrating an example (Example 2) of the configuration of the image input device of the present invention.

FIG. 3 is a diagram showing an example (Example 3) of the configuration of the image input device of the present invention.

FIG. 4 is a diagram showing an example (Example 4) of the configuration of the image input device of the present invention.

FIG. 5 is a diagram showing an example (Example 5) of the configuration of the image input device of the present invention.

FIG. 6 is a diagram illustrating a configuration of a conventional image input device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Line sensor camera 2, 2a, 2b Linear light source 3, 3a, 3b Half mirror 4, 4a, 4b Light diffusion plate 5 Lens 6 Mirror with a slit 7 Light absorber 11 Inspection object 21a, 21b Transport belt 22a, 22b Belt Rollers 23, 24, 25, 26 Holding rollers 27 Guide rollers

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Yasutaka Fujii 1-1-1 Ichigaya-Kaga-cho, Shinjuku-ku, Tokyo Dai-Nippon Printing Co., Ltd. F-term (reference) 2G051 AA32 AA34 AA37 AB02 AB11 CA03 CB01 CC12 CD04 DA06 EA12 EA16 ED08 5C054 AA01 CA04 CC03 CC05 CC06 EB05 GB01 HA01 5C072 AA01 BA01 CA02 CA09 DA02 DA05 DA16 DA21 DA23 EA05 NA01 XA10

Claims (6)

[Claims] An image input apparatus for obtaining image data by capturing an image of an object to be imaged by combining main scanning by a line sensor camera and sub-scanning by transporting the object to be imaged, comprising: a line sensor camera; And an optical axis conversion unit, wherein the line sensor camera captures an image of a linear imaging area of the object to be imaged via the optical axis conversion unit, and the linear light source is connected to the optical axis conversion unit via the optical axis conversion unit. Irradiating the linear imaging region with light, wherein the optical axis conversion unit matches the optical axes of the line sensor camera and the linear light source on the imaging object side and separates the optical axis on the opposite side. Image input device. 2. An image input apparatus according to claim 1, further comprising a light diffusing means between said linear light source and said optical axis converting means. 3. An image input apparatus according to claim 1, further comprising a light condensing means between said linear light source and said optical axis converting means. 4. An image input apparatus according to claim 1, wherein said optical axis conversion means is a half mirror. 5. The image input device according to claim 1, wherein said optical axis conversion means is a mirror having a slit. 6. The image input device according to claim 1, wherein an optical axis of said line sensor camera is non-parallel to a normal to a surface of said linear imaging area of said article to be imaged. An image input device, characterized in that: