JPS6087564A - Color original reader - Google Patents

Abstract

PURPOSE:To correct a picture signal level by comparing the level of a picture signal of each color with a set value when reading a white reference plate and setting a storage time of a storage image sensor for each color so as to make the result of comparison coincident. CONSTITUTION:An optical image of the white reference plate 102 lighted by a white color lamp 101 is separated into three primary colors R, G, B with filters 104-106 and formed respectively on CCD image sensors 110-112 via lenses 107-109 and converted into a color picture signal. A timing control section 116 sets the storage time of the CCD image sensors 110-112 to the initial value as to first one line or several lines and discriminates whether or not the storage time is to be increased depending on the state of an output signal of comparators 117-119. The timing control section 116 resets the storage time of the CCD image sensors 110-112 according to the result of discrimination, reads one or several lines and discriminates from the output signal of the comparators 117- 119 whether or not the storage time is proper. Thus, the coincidence is obtained by the comparison.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a color document reading device, and more specifically to a CCD reading device.
The present invention relates to a color document reading device using a storage type image sensor such as an image sensor.

Structure of the Conventional Example and Its Problems FIG. 1 is a block diagram of a conventional color original reading device. In this figure, 1 is a white lamp for illuminating the white reference plate 2 or original 3, and 4, 5° and 6 are R (red) respectively.
, G (green), B (blue) color separation filter, 7, 8.9
is a lens, and 1o and 11.12 are CCD image sensors. Reference numerals 13, 14, and 16 are amplifiers, and 16 is a timing control section for the CCD image sensors 10, 11, and 12.

To explain the operation, an optical image of a white reference plate 2 or a document 3 illuminated by a white lamp 1 is divided into three primary colors R, G, and B by filters 4, 5', and 6 that constitute a color separation system. The signals are separated into colors, and images are formed on CCD image sensors 10, 11, and 12 through a lens 7.8.9, respectively, and converted into image signals for each color. The main scanning of this reading scan is performed by CCD
Image sensors 10, 11, and 12 perform sub-scanning, and sub-scanning is performed by moving the document 3. However, sub-scanning of the white reference plate 2 is not performed. CCD image sensor 10.
The image signal output from 11.12 is sent to amplifiers 13 and 14.
, 15, and the R, G, and B image signals V
It is outputted to the outside as r, Vg, and Vb. Note that the accumulation time of the COD image sensor 10°11.12 is constant.

Now, from the relationship of the spectral characteristics of the COD image sensors 10, 11, 12, filters 4, 5, 6, white lamp 1, etc.,
Even when reading the white reference plate 2, the levels of the image signals output from the COD image sensors 10, 11, 12 are not the same. Conventionally, therefore, the amplification factors of the amplifiers 13.degree.14.15 are adjusted so that the image signals V.sub.r, V.sub.g, and vb are at the same level when reading the white reference plate 2.

However, in such a configuration, there is a problem that the S/N ratio of the image signal of the color whose amplification factor is set to be high becomes poor, and the intermediate level cannot be reproduced correctly.

OBJECTS OF THE INVENTION The present invention solves the above-mentioned conventional problems, and it is an object of the present invention to provide a color document reading device that can equalize the levels of image signals of each color without deteriorating the S/N ratio.

Structure of the Invention The present invention focuses on the fact that the output level of an accumulation type image sensor has a nearly linear relationship with the accumulation time, and that the output level can be controlled by changing the accumulation time. Means for comparing the level of the image signal outputted from each of the storage type image sensors provided with the set value thereof, and means for setting the storage time of each storage type image sensor so that the comparison by the means agrees are provided. In particular, it seeks to achieve the above-mentioned objectives.

Description of examples Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 is a block diagram of a color document reading device according to an embodiment of the present invention. In this figure, 101 is a white lamp for illuminating the white reference plate 102 or the original 103;
104, 105, 106 are R (red) and G (green) respectively
, B (blue) color separation filter, 107, 108, 10
9 is a lens, and 110, 111, and 112 are COD image sensors. 113, 114, 115 are amplifiers with the same amplification factor, 116 is a COD image sensor 110.11
．． 1. ．． 1.12 timing control section.

117, 118, 119 are comparators, amplifier 113
．． R and G output from 114 and 115.

The image signals Vr, Vg, and Vb of B are set by the voltage setting device 120.1.
21, 122 set voltage V1. Compare with V2°VS (set value). These comparators 117, 118, 11
The output signal 9 is input to the timing control section 116.

Next, the operation will be explained. Before reading the original, use the white reference plate 1.
02 is read. The optical image of the white reference plate 102 illuminated by the white lamp 1°1 is divided into R, G, and B by filters 104, 105, and 106 that constitute a color separation system.
The colors are separated into three primary colors, and the lenses 107, 108, 1
COD image sensor 110, 111.1 via 09
12 and converted into image signals for each color.

This reading scan is performed multiple times. Timing control section 11
6 is CO for the first line or several lines.
The accumulation times of the D image sensors 11o, 111, and 112 are set to initial values, and it is determined whether the accumulation times should be increased or shortened based on the states of the output signals of the comparators 117, 118, and 119. According to this determination result, the timing control unit 116 controls each COD image sensor 11Q, 111
, 112 to read one line or several lines, comparators 11.7, 118, 119
It is determined from the output signal whether the accumulation time is appropriate. In this way, the accumulation time is adjusted and the comparator 117.
If a match is found by comparing 118 and 119, that is, ■r-
v1, vq=v2. (2) When a state where b=v3 is reached, the accumulation time at that time is finally set. This accumulation time is fixed until reading of the white reference plate 102 starts again after reading the document.

FIG. 3 is an explanatory diagram of the above-mentioned accumulation time setting.

The figure (-) shows the initial value of the accumulation time (5ms e c /l
Image signals V r , V g when set to 1ne)
, indicates the level of Vb. In this way, the levels will vary due to differences in the sensitivity of the reading system for each color.

Figure (b) shows the image signal V after the accumulation time is determined.
It shows the levels of r, Vg, and Vb. however,
Here, V1=V2=V and 3=1 volt are set. In this case, the COD image sensor 11o.

The accumulation time of 111 and 112 is 5m5ec/1, respectively.
tne, 5m5ec/line, 10tusec/1
It is ine.

As described above, COD image sensor 110.111
．． When the setting of the accumulation time in 112 is completed, the original 103 is conveyed to the reading position, the optical image is separated into colors, and the COD
The images are formed on image sensors 110, 111, and 112, and converted into image signals. At this time, variations in the sensitivity of the reading system for each color have been corrected by adjusting the accumulation time, so the image plan V r is free from level differences due to such variations in sensitivity.
, V g , and Vb can be obtained. And, such correction is performed by COD before and after amplifiers 117, 118, 119.
The image sensors 110, 111, and 112 perform this process, and the input signal levels of these amplifiers are optimized, so that the image signals of colors with low sensitivity (V r , V q * v
In b), the S/N ratio does not deteriorate significantly.

Effects of the Invention As described above, the present invention provides a means for comparing the level of an image signal of each color with a set value when reading a white reference plate, and an accumulation type image sensor for each colorant so that the comparison by the same means is consistent. Since the image signal level is corrected at the storage type image sensor stage by providing a time setting means, it is possible to equalize the image signal level of each color without causing deterioration of S/H as in the conventional case. You can get effects such as:

[Brief explanation of drawings]

Figure 1 is a block diagram of a conventional color document reading device;
The figure is a block diagram of a color document reading device according to an embodiment of the present invention, and FIG. 3 is an explanatory diagram of storage time setting. 101... White lamp, 102... White reference plate, 103... Original, 104, 105, 1
06... Color separation filter, 107, 108,
109... Lens, 110, 111.112.
...COD image sensor, 113, 114
, 115...Amplifier, 116...Timing control section, 117, 118°119...
Comparator, 120, 121, 122... Voltage setting device. Name of agent: Patent attorney Toshio Nakao (OL) (b)

Claims (1)

[Claims] By color-separating the optical image of the document or white reference plate and forming it on multiple storage-type image sensors installed for each color through a color separation system, image signals for each color are output from each of the storage-type image sensors. The color document reading device comprises means for comparing the level of each color image signal with a set value when an optical image of the white reference plate is formed on each storage type image sensor, and the means A color document reading device characterized in that it includes means for setting the storage time of each of the storage type image sensors so that the comparisons match each other. ffi.