JPH06217077A - Color picture inputting device - Google Patents

Abstract

PURPOSE:To provide a color picture inputting device in which picture data whose quality is satisfactory without any vertical stripes can be obtained even when a picture is read at a high speed. CONSTITUTION:In a color picture inputting device A', at the time of obtaining the picture data by scanning a color original 1 by successively resolving a light from the color original 1 into plural chrominance components by a color resolving filter unit 5, and image-forming it on a CCD linear image sensor 4 constituted of plural picture elements, the CCD linear image sensor 4 is already irradiated with a bias light from a bias light source 2'. Thus, even at the time of reading the picture at the high speed, the picture data whose quality is satisfactory without any vertical stripes can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color image input device, and more particularly to a color image input device used in a color image processing device such as a color facsimile or a color image scanner.

[0002]

2. Description of the Related Art Conventionally, a color original is irradiated with light, and reflected light or transmitted light from the original is separated into a plurality of color components by a color separation filter and is scanned. A color image input device is known in which image data is obtained by forming an image on a document and reading a color image on a document for each color component. FIG. 3 is a schematic diagram showing a schematic configuration of an example of the conventional color image input device A as described above, FIG. 4 is a plan structural view of a color separation filter unit, and FIG. 5 is a schematic diagram showing a schematic configuration of a CCD linear image sensor. It is a figure. In FIG. 3, the light emitted from the light source 2 to the reading line on the color original 1 is transmitted through the original surface and then condensed by the lens system 3 to form an image on the CCD linear image sensor 4 which is an image sensor. To do.
The color separation filter unit 5 in the path of this imaging optical system
It is attached near the lens system 3. As shown in FIG. 4, the color separation filter unit 5 is provided with filters 5r, 5g, and 5b for the three primary colors of red (R), green (G), and blue (B), and the rotary shaft 7 is centered. By rotating, each of the above filters 5
r, 5g, and 5b can be sequentially placed on the optical path.
Therefore, the color image on the original 1 can be read by the CCD linear image sensor 4 for each color component. CCD
The inside of the linear image sensor 4 has a structure as shown in FIG. 5, and first, charges proportional to the amount of incident light are accumulated in a capacitor C of a sensor unit S including a plurality of pixels P, P, .... Next, charge accumulated in the capacitor C is CC
Move to D analog shift register R. Then, by sequentially moving this charge in the CCD analog register R, a signal proportional to the amount of incident light of each pixel P, P, ... Is extracted. In this way, image data (signal) for each scan
I was able to get

[0003]

In the conventional color image input apparatus A as described above, when an image is read at a high speed, vertical stripes having periodicity may occur in a highly saturated portion of the image. . This is because when the electric charges are transferred from the sensor unit S of the CCD linear image sensor 4 to the CCD analog shift register R, some of the electric charges remain in the sensor unit S as they are without transferring all the electric charges, and the electric charges at the time of the next scanning are changed. It's because it gets mixed in. Moreover, each pixel P, P,
Since there is a variation in the ratio of the remaining charge between R, G, and
In the case of the original 1 having a large difference in the signal level of each color of B, each pixel P, P, ... Has a different color. For this reason, the portion of the pixel P where a large amount of electric charge remains may be seen as a vertical stripe. In order to solve the problems in the prior art, the present invention has improved a color image input device and provides a color image input device which can obtain high-quality image data without vertical stripes even when an image is read at high speed. It is intended to be provided.

[0004]

In order to achieve the above-mentioned object, the present invention obtains image data by scanning light from a color original while sequentially separating it into a plurality of color components and forming an image on an image sensor. The color image input device is configured as a color image input device characterized in that the image pickup device is always irradiated with bias light. Further, it is a color image input device using a light source for irradiating the color original with light as the bias light source.

[0005]

According to the present invention, when the light from a color original is sequentially separated into a plurality of color components and scanned to form an image on the image sensor to obtain image data, bias light is constantly applied to the image sensor. Is irradiated. By this irradiation, it is possible to remove a component causing a vertical stripe from the output signal of the image pickup device. As a result, high-quality image data with no vertical stripes can be obtained even when the image is read at high speed.

[0006]

Embodiments of the present invention will be described below with reference to the accompanying drawings for the understanding of the present invention. The following embodiments are examples of embodying the present invention and are not intended to limit the technical scope of the present invention. FIG. 1 is a schematic diagram showing a schematic configuration of a color image input device A'according to an embodiment of the present invention, and FIG. 2 is a graph showing the relationship between the amount of bias light and the size of streak components. The same reference numerals are used for the elements common to the conventional color image input apparatus A shown in FIG. As shown in FIG. 1, a color image input device A'according to this embodiment includes a light source 2, a lens system 3, a CCD linear image sensor 4 (corresponding to an image pickup device).
And a color separation filter unit 5, and the color separation filter unit 5 that rotates the light from the color original 1
This is the same as the conventional example in that image data is obtained by capturing an image on the CD linear image sensor 4. However, the present embodiment is different from the conventional example in that the bias light source 2'constantly irradiates the CCD linear image sensor 4 with the bias light. The basic principle of the operation of the device A'will be described below with reference to FIG. 2 shows the CC of this device A '.
This is the result of irradiating the D linear image sensor 4 with bias light. In the figure, the horizontal axis represents the amount of bias light and the vertical axis represents the magnitude of the streak component indicating the amount of vertical streak. It can be seen from FIG. 2 that as the bias light amount increases, all the red (R), green (G), and blue (B) streak components become smaller, and when the light amount exceeds a certain amount, all streak components disappear. This is for the following reason. That is, in the CCD linear image sensor 4, as the amount of incident light on the sensor increases, the amount of charge ΔQ remaining in the sensor unit S for the next scanning increases. However, the rate of increase of the charge amount ΔQ is smaller than the rate of increase of the charge amount Q newly generated by the next scan, and the ratio of both charge amounts ΔQ and Q decreases as the incident light amount increases. The rate of this decrease is slightly different depending on the signal level difference between the R, G, and B color components, but if the incident light amount exceeds a certain value, the amount of charge ΔQ remaining in the next scan can be ignored, and the reduction rate of the next scan is new. The generated charge amount Q becomes dominant. Therefore, the streak component due to the charge amount ΔQ almost disappears. In the apparatus A'using the above principle, a so-called optical bias for increasing the incident light amount is applied to the CCD linear image sensor 4 by the bias light source 2 ', so that a constant light amount irrespective of the density of the original document 1 is constantly CCD. It is incident on the linear image sensor 4.
By this optical bias, the streak component can be removed from the output signal of the CCD linear image sensor 4. As a result, high-quality image data with no vertical stripes can be obtained even when the image is read at high speed. In the above embodiment, the bias light source 2'is provided separately from the light source 2 for irradiating the color original 1 with light.
The light source 2 can also be used as the bias light source 2'by guiding the light emitted from the CCD linear image sensor 4 through a reflecting mirror or the like. In this way, the bias light source 2'can be omitted and the device A'can be made compact. In the above embodiment, the color separation filter unit 5 of three colors of RGB is rotated and used, but in actual use, there is no problem even if another type of filter is used.

[0007]

Since the color image input device according to the present invention is configured as described above, the component causing the vertical stripe can be removed from the output signal of the CCD linear image sensor 4 by the optical bias. as a result,
Even when an image is read at high speed, good quality image data without vertical stripes can be obtained.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a schematic configuration of a color image input device A ′ according to an embodiment of the present invention.

FIG. 2 is a graph showing the relationship between the amount of bias light and the size of streak components.

FIG. 3 is a schematic diagram showing a schematic configuration of an example of a conventional color image input device A.

FIG. 4 is a plan view of a color separation filter unit.

FIG. 5 is a schematic diagram showing a schematic configuration of a CCD linear image sensor.

[Explanation of symbols]

 A '... Color image input device 1 ... Color original 2' ... Bias light source 4 ... CCD linear image sensor (corresponding to image sensor) 5 ... Color separation filter unit

Claims (2)

[Claims] 1. A color image input device for sequentially scanning light while separating light from a color document into a plurality of color components and forming an image on the image pickup device to obtain image data, wherein the image pickup device is constantly irradiated with bias light. A color image input device characterized by: 2. The color image input device according to claim 1, wherein a light source for irradiating the color original with light is used as the bias light source.