JPH11289433A - Digital picture reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve work efficiency in a range that does not affect picture quality by constituting a digital picture reader so that timing when a reference board for shading correction is exposed/read can be changed. SOLUTION: When a copy start key is depressed (S1), it is judged whether a system is set to either of a color or a monochrome mode (S2). When the system to be set to the color mode (picture quality preferential mode) is judged, processing for exposing and reading a reference plate is started (S3), a shading correction value is updated based on the result (S4) and a copy processing (S5) is executed by the shading correction value. On the other hand, when the system to be set to the monochrome mode (speed preferential mode) is judged, the copy processing (S5) is speedily started. When the copy processing (S5) terminates thoroughly, the reference board is exposed/read (S6). The shading correction value is updated based on the result (S7).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital image reading apparatus which exposes and reads a reference plate and performs shading correction in a light receiving element such as a CCD.

[0002]

2. Description of the Related Art In general, in a digital image reading apparatus, even if reflected light from a document having a uniform density in the scanning line direction is detected by a light receiving element, variations in pixel sensitivity in the light receiving element and variations in the amount of transmitted light in a lens occur. Due to variations in the amount of light in the longitudinal direction of the light source for manuscript illumination (particularly different between the center and both ends), and the deterioration of the light source, the output from the light receiving element corresponding to each pixel is not necessarily a uniform value. Not necessarily. Therefore, so-called shading correction is performed to correct these. As an example of a procedure for performing the shading correction, data on white is obtained by exposing a white reference plate with light from a light source, and data on black is obtained with the light source turned off. The data for each white / black obtained in this way is determined, for example, by setting white to 255 and black to 0, and dividing the data relating to white / black into 256 steps to obtain the characteristics of each pixel in the light receiving element. . Then, the output from the light receiving element at the time of scanning the original is corrected by the shading correction value based on the obtained characteristics.

[0003]

By the way, in the exposure and reading operation of the reference plate for shading correction as described above, conventionally, a reading start button (for example, a copy start button in a copying machine) is pressed. And before the start of reading the manuscript. However, if the exposure / reading operation of the reference plate is performed every time before the reading of the document is started, it takes a long time to read the first document, which causes a reduction in work efficiency. Also, since the shading correction value obtained by the exposure and reading operations of the reference plate rarely changes greatly in a short time, unless a high image quality is required, a slightly earlier shading correction value is used. However, there is no particular problem. The present invention has been made in view of the above circumstances, and by making it possible to change the timing of performing the exposure and reading operations of the reference plate for shading correction, it is possible to improve the working efficiency within a range that does not affect the image quality. It is an object of the present invention to provide a digital image reading device that can be improved.

[0004]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a digital image reading apparatus for exposing, reading and shading correction of a reference plate. When the next image reading operation is in the predetermined speed priority mode, the shading correction value using the previous read data is adopted, and when the next image reading operation is in the predetermined image quality priority mode, The digital image reading apparatus is characterized in that the exposure and reading processes are performed again before the image reading operation is started, and a shading correction value using read data obtained therefrom is adopted. The above-mentioned predetermined speed priority mode and image quality priority mode can be arbitrarily set, respectively.

[0005]

According to the digital image reading apparatus of the present invention,
After the end of a series of image reading operations, the exposure and reading processes of the reference plate are always performed. If the next image reading operation is a predetermined speed priority mode such as a monochrome mode, the exposure and reading processing of the reference plate are not performed immediately before the reading operation, and the shading correction value using the previous reading data is not obtained. Adopted. Therefore, the work efficiency is very good. On the other hand, if the next image reading operation is a predetermined image quality priority mode such as a color mode, the above exposure and reading processes are performed again before the image reading operation is started, and shading correction using the read data obtained therefrom is performed. The value is adopted. Therefore, although it takes time until the start of copying, a high-quality image faithful to the original is obtained. As described above, it is possible to improve the work efficiency within a range where the image quality of the read image is not reduced.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments and examples of the present invention will be described below with reference to the accompanying drawings to facilitate understanding of the present invention. The following embodiments and examples are mere examples embodying the present invention, and do not limit the technical scope of the present invention. FIG. 1 is a flowchart showing a sequence of a series of copying processes including shading correction of the digital color copying machine A1 according to the embodiment of the present invention.
FIG. 2 is a sectional view showing a schematic configuration of the image reading device 1 of the digital color copying machine A1 according to the embodiment of the present invention.
In the present embodiment, an example is shown in which the digital image reading apparatus according to the present invention is embodied as the image reading apparatus 1 of the digital color copying machine A1. First, the schematic configuration of the image reading device 1 of the digital color copying machine A1 according to the present embodiment will be briefly described. As shown in FIG. 2, a contact glass 2 on which an original is set is mounted on an upper portion of the image reading device 1, and an exposure unit 4 integrally including a light source 4a and a mirror 4b is provided below the contact glass 2. Mirror 5
An optical system including a mirror unit 5, a lens 6, a light receiving element 7, and the like integrally configured with a, 5b and the like is provided. Light emitted from the light source 4a and reflected by the original surface set on the contact glass 2 is guided by the mirrors 4a, 5a and 5b and received by the light receiving element 7 via the lens 6. The exposure unit 4 and the mirror unit 5 include a belt 8, a drive shaft 9, a wire 1,
2 is driven in the left and right direction in FIG. 2 by driving of the motor 11 through, for example, exposure and reading of the entire surface of the original set on the contact glass 2. The position adjacent to the contact glass 2 is shown in FIG.
A belt-shaped reference plate 3 is attached in the out-of-plane direction. When performing shading correction, the exposure unit 4 and the mirror unit 5 are moved to below the reference plate 3, and the exposure and reading of the reference plate 3 are performed. The operation control of the image reading apparatus 1 such as the movement control of the exposure unit 4 and the mirror unit 5 is performed by a control unit (not shown).

Next, the procedure of shading correction by the digital color copying machine A1 having the above-described image reading apparatus 1 will be described with reference to the flowchart shown in FIG. An original is set on the contact glass 2 and various settings (for example, paper size, density, number of copies,
After a setting such as color / monochrome switching is performed, when a copy start button (not shown) is pressed (step S
1) In the control unit (not shown), it is determined whether the mode is set to color or monochrome (step S2). Here, if it is determined that the mode is the color mode (an example of the image quality priority mode), the control unit controls the reference plate 3
Is started (step S3), the shading correction value is updated based on the result (step S4), and the copy process is performed while correcting the output from the light receiving element by the shading correction value (step S3).
5) is performed. As described above, when copying in the color mode, since the image is read based on the shading correction value obtained immediately before the start of the copy, it takes a long time before the start of the copy, but a high image quality faithful to the original is taken. Is obtained. On the other hand, if it is determined in step S2 that the mode is the monochrome mode (an example of the speed priority mode), the processes in steps S3 and S4, that is, the exposure / reading process of the reference plate 3 and the update of the shading correction value are performed. The copying process (step S5) is started immediately without being performed. In this copy processing, the shading correction value obtained immediately after the previous copy processing (steps S6 and S7 described later) is used as it is. As described above, when copying in the monochrome mode, the exposure and reading of the reference plate are not performed immediately before the start of copying, and the first copy is started immediately, so that the work efficiency is extremely high. . In addition, since the shading correction value obtained by the exposure and reading processing of the reference plate rarely changes greatly in a short time, especially in a monochrome mode in which the image quality is not sensitive, the shading correction value is obtained immediately after the previous copy processing. Even if the shading correction value obtained in (1) is used, an image having no practical problem can be obtained. If the first copy process after manufacturing is in the monochrome mode, for example, a shading correction value set as an initial value at the time of shipment from the factory is used, or only in this case, the above-described step is performed before the start of the copy process. Steps S3 and S4 are performed. The processes of steps S3 and S4 may be performed at the time of warm-up when the power is turned on. When the copying process of step S5 is completed, the exposure and reading process of the reference plate is performed (step S6), and the shading correction value is updated based on the result (step S6).
7). The exposure and reading process of the reference plate is performed after the end of a series of copying processes, so that the efficiency of the copying operation is not affected. The updated shading correction value is used when the next copy is in the monochrome mode, as described above.

As described above, in the digital color copying machine A1 according to the present embodiment, after the series of copying processes is completed, the reference plate is exposed and read, and the next copy is performed in the monochrome mode (speed priority). If the next copy is in the color mode (an example of the image quality priority mode), the above-described exposure and reading process is performed again before the start of the copy if the next copy is in the color mode (an example of the image quality priority mode). In addition, since the shading correction value using the read data obtained therefrom is adopted, when the image quality is prioritized, a high-quality image using the accurate shading correction value immediately before copying can be obtained as before, and the speed (work efficiency) When priority is given to the above, the exposure and reading processing of the reference plate immediately before copying is omitted, and the previous shading correction value is used. To start the copy Ya or to,
Work efficiency is improved. Therefore, it is possible to improve the work efficiency within a range where the image quality of the read image is not reduced.

[0009]

In the above embodiment, an example has been described in which the speed priority mode is the monochrome mode and the image quality priority mode is the color mode. However, the present invention is not limited to this. For example, in a monochrome copying machine or the like, the speed priority mode may be a character mode and the image quality priority mode may be a photograph mode. As for the color mode, three-color color can be set as the speed priority mode and four-color color can be set as the image quality priority mode. Further, the speed priority mode and the image quality priority mode may be arbitrarily selectable. It goes without saying that the image reading apparatus according to the present invention is widely applicable not only to color digital copying machines but also to monochrome copying machines and facsimile machines.

[0010]

As described above, according to the present invention, in a digital image reading apparatus for exposing, reading, and shading correction of a reference plate, exposure and reading of the reference plate are performed after a series of image reading operations. At the same time, if the next image reading operation is in the predetermined speed priority mode, the shading correction value using the previous read data is adopted. If the next image reading operation is in the predetermined image quality priority mode, the image reading operation is started. The digital image reading apparatus is characterized in that the above-mentioned exposure and reading processes are performed again and a shading correction value using the read data obtained therefrom is adopted. As a result, high-quality images using accurate shading correction values immediately before copying can be obtained, and priority is given to speed (work efficiency). Quickly work efficiency is improved by initiating the copying using the previous shading correction value is omitted exposure and reading process of the reference plate of the copy just before the case. Therefore, it is possible to improve the work efficiency within a range where the image quality of the read image is not reduced.

[Brief description of the drawings]

FIG. 1 is a flowchart showing a series of copying processes including shading correction of a digital color copying machine A1 according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view illustrating a schematic configuration of an image reading device 1 of the digital color copying machine A1 according to the embodiment of the present invention.

[Explanation of symbols]

 1. Image reading device 3. Reference plate

Claims (3)

[Claims] 1. A digital image reading apparatus for exposing and reading a reference plate and performing shading correction.
After the end of a series of image reading operations, exposure and reading of the reference plate are performed. If the next image reading operation is in a predetermined speed priority mode, the shading correction value using the previous read data is adopted, and the next image reading operation is performed. If the image reading operation is in a predetermined image quality priority mode, the exposure and reading processes are performed again before the image reading operation is started, and a shading correction value using read data obtained therefrom is adopted. Reader. 2. The digital image reading device according to claim 1, wherein the predetermined speed priority mode is a monochrome mode, and the predetermined image quality priority mode is a color mode. 3. The digital image reading apparatus according to claim 1, wherein said predetermined speed priority mode is a character mode, and said predetermined image quality priority mode is a photograph mode.