JPS60201770A - Color picture reader - Google Patents

Abstract

PURPOSE:To attain the high-speed reading with a color picture reader by scanning plural light sources of different spectral characteristics with blinking and operating two types of picture signals obtained from the same reading line and producing the color separated picture signals. CONSTITUTION:The reflected light given from an original 11 forms an image on an image sensor line 17 by an optical lens 16 and undergoes the photoelectric conversion. A picture signal 35 is supplied to a color converter 38 after A/D conversion and also delayed every line by two line memories 39 and 40. Then one- and two-line delay signals 42 and 43 are supplied to the converter 38. Here blue, red and green light sources 13-15 have blinking start time points shifted by 1/3 main scan period from each other. Thus three types of picture signals are obtained with mutual overlap for each main scan. Therefore a picture signal 37 and picture signals 42 and 43 obtained by delaying the signal 37 by one and two lines respectively are applied to the converter 38 to obtain primary color signals R, G and B.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a color image reading device that can read color images using a plurality of light sources.

[Prior art]

Color image processing devices such as color copying machines and color facsimile machines separate image information on a document into two or more colors and convert them into electrical signals. There are two types of color reading devices for this purpose: ■ One that separates the wavelengths using static optical components such as a guichroic mirror, and ■ The one that separates the wavelengths by rotating a disc with multiple filters attached in the optical path. The one you select is traditionally used. However, the former method has a drawback in that the spectral characteristics change depending on the incident angle of the mirror and the like. On the other hand, the latter requires a disk rotation mechanism, which has problems with its accuracy and reliability.

Therefore, a color image reading device using a plurality of light sources with different spectral characteristics has been proposed. FIG. 1 shows a reading section of a color image reading device that reads three colors. Near the platen glass 12 on which the original 11 is placed, there is a front light lamp 13 that selectively emits blue wavelength components.
A total of three fluorescent lamps are arranged: a red band light 14 that selectively irradiates red wavelength components, and an edge band light 15 that selectively irradiates green wavelength components. The document 11 is configured to move in an arrow direction (sub-scanning direction) perpendicular to the longitudinal direction of these fluorescent lamps 13 to 15 (perpendicular to the drawing). Light reflected from the original 11 by the fluorescent lamps 13 to 15 is focused by a common optical lens 16 and formed into an image on an image sensor 17. In the image sensor 17, photoelectric conversion elements are arranged in a line in the longitudinal direction of the fluorescent lamps 13 to 15, and images are read line by line.

FIG. 2 shows the blinking timing of each fluorescent lamp and the image signal after photoelectric conversion. In this color image reading device, the time required to read the I line is divided into approximately four equal parts, and the front band light 13 is turned on only during the first main scanning section t1 (see Fig.
stomach)). For example, the front strip light 13 using calcium dungestate as a phosphor has good flickering response characteristics and almost no afterglow. In the next main scanning section t2, the edge strip light 15 is turned on (FIG. 2(B)). At this time, the blue image signal 18 is read out from the image sensor 17 ((d) in the same figure).
. Further, in the next main scanning section t3, the red band light 14 is turned on (FIG. 3(C)). At this time, the green image signal 19 is read out from the image sensor 17 ((d) in the same figure).
. The red band light 14 uses, for example, magnesium germanate as a phosphor, and has poor blinking response characteristics. Therefore, the afterglow time is long, about 2 msec. Therefore, the last main scanning section t4 is used for processing this afterglow. In this main scanning period as well, the red image signal 20 in the subsection t3 is read out in the fourth period ((d) in the same figure).

Thereafter, the reading operation for each line is repeated in the same manner.

As described above, the proposed color image reading device performs reading by flashing a fluorescent light, so it has the advantage of being compact, low cost, and highly reliable. However, fluorescent lights generally have a blinking response of 1. Due to the poor quality, the reading position during the afterglow time is restricted, and the reading speed cannot be sufficiently increased.

[Purpose of the invention]

In view of these circumstances, an object of the present invention is to provide a color image reading device that can perform high-speed reading while blinking a plurality of light sources.

[Structure of the invention]

In the present invention, a plurality of light sources for irradiating the original with different spectral characteristics, a photoelectric conversion element that receives light reflected from the original by these light sources and photoelectrically converts it as an image signal, and a photoelectric conversion element for each reading line. light source lighting control means for lighting some of the light sources redundantly in a specific main scan for a predetermined number of repeated main scans, and changing the combination of the redundant light sources for each main scan; The color image reading device is provided with a color conversion means for calculating two or more types of image signals obtained thereby, respectively corresponding to the main scanning position, and creating color-separated image signals.

Color separation is possible with one or more light sources turned on continuously over two or more scanning sections, and high-speed reading is possible. For the calculation of image signals in the color conversion means, an image signal delay means may be provided to process the image signals obtained for each main scan at the same timing.

〔Example〕

The present invention will be described in detail with reference to Examples below.

FIG. 3 shows a color image reading device according to an embodiment of the present invention. This device uses three types of fluorescent lamps13.
-15 is used to perform three-color reading. The three lighting devices 31-33 are individually controlled by a lighting control circuit 34, and share the lighting control of the three types of fluorescent lamps 13-15. Reflected light from the irradiation of the original 11 is imaged by an optical lens 16 onto an image sensor 17 made of a CCD, and is photoelectrically converted. The image signal 35 obtained thereby is converted into a digital quantity by an A/D converter 36. The converted image signal 37 is supplied as is to the color conversion circuit 38, and is also supplied to two line memories 39.
40, and are supplied to the color conversion circuit 38 as a 1-line delayed image signal 42 and a 2-line delayed image signal 43, respectively. The color conversion circuit 38 uses these three types of image signals 37, 42, and 43 to convert red (R)
Image signals 44 to 46 are created when the three primary colors of , green (G), and blue (B) are individually irradiated onto the original.

FIG. 4 shows the lighting timing of each fluorescent lamp in such a color image reading device and the color characteristics of the image signal output from the image sensor. In this device, the time required to read one line is divided into three main scanning sections: 1. -13.

As shown in FIG. 4(A), the red band light 14 is controlled to be turned on at the start of the third main scanning section t3, and is controlled to be turned off at the end of the first main scanning section t1. As shown in the figure, the edge wall light 15 is controlled to be turned on at the beginning of the first main scanning section t, and is controlled to be turned off at the end of the second main scanning section t2. In addition, as shown in FIG.
is controlled to be lit at the start of the third main scanning section t.
At the end of step 3, the light is turned off.

In this way, each of the fluorescent lamps 13 to 15 is lit continuously over two scanning sections, so that two fluorescent lamps are controlled to be lit in one main scanning section. Therefore, the wavelength components of the irradiated light from the blue, red, and green fluorescent lamps 13 to 15 are respectively r.

In the first main scanning section t1, expressed as g, an image signal 35 (FIG. 4(d)) corresponding to the wavelength component (r+b) accumulated in the previous scanning section is obtained.

Similarly, in the second main scanning section t2, the wavelength component (r+g)
An image signal 35 corresponding to the wavelength component (g+b) is obtained in the third main scanning section. These image signals 35 are A/D converted, and some of them are delayed by line memories 39 and 40 before being supplied to the color conversion circuit 38.

FIG. 5 shows a specific example of this color conversion circuit. The color conversion circuit 38 includes three sets of coefficient multipliers 48-1 to 48.
-3.49-1 to 49-3.5〇-1 to 50-3, and three adders 52 for adding the multiplication results for each set.
~54 (+iij).

The coefficients of the first set of coefficient multipliers 48-1 to 48-3 are ml+, , 2, m+3, and the coefficients of other sets are also IT
I 21, m 22, m23 or m31, m32, m
33. Also, the image a corresponding to the wavelength component (r+b)
The signal level (digital quantity) of No. 35 is [r + b )
Similar signal levels of the image signal 35 in other scanning sections are expressed as [r+'g) and [g+b:], respectively.

In this case, the first set of circuit portions performs the following calculation and outputs a signal level [R] when it is assumed that the red band light 14 is turned on alone.

[R] ””m, I:r+g:] +m+2(g+b,
] -1-ml3[b0r]...(1) In addition, the second set of circuits performs the following calculation to calculate the result when it is assumed that the edge wall light 15 is turned on alone. signal level CG).

CG)”m2+ [:r+g]+m22[:g+b)+
m23Cb 10r ] -- (2) Further, the third set of circuits performs the following calculation and outputs the signal level [B] when it is assumed that the blue fluorescent lamp 13 is turned on alone.

[13) ””lT13+ (r 10g) +m32C
g+b) 10m33Cb 10r ] --' (3) Assuming that the color characteristics of each of the fluorescent lamps 13 to 15 and the spectral sensitivity of the image sensor 17 are ideal, each coefficient is 1/2 or -172, resulting in the following:

- [r] ...... (1)' - [g] ...... (2)' In this way, the three types of image signals 44 to 46 obtained from the color conversion circuit 38 are three types. This is an image signal obtained when the fluorescent lamps 13 to 15 are exclusively turned on. Of course, in an actual device, it is necessary to consider the characteristics of the fluorescent lamp, etc., and set each coefficient to a predetermined value.

[Modified example]

In the embodiments described above, all the fluorescent lamps or light sources are controlled to blink, but color images can be read in the same way even if one light source with poor response characteristics is blinked continuously.

FIG. 6 shows the timing of a color image reading device as an example. In this device, front strip light 1
3 is turned on during the main scanning section t1 ((a) in the same figure), and the edge band light 15 is turned on during two main scanning sections 'l+ and t2 ((b) in the same figure). Red band light with poor light response 1
4 is to make continuous dots while reading is being carried out (same figure (
Ha)). As a result, the first to third main scanning sections t1
~t3 have wavelength components (r) and (r+g+b), respectively.
, (r 10g) is controlled (as shown in the figure (
d)).

This color image reading device also has a delay memory for one scan (
line memory) and a delay memory for two scans (line memory) to simultaneously supply three types of image signals to a color conversion circuit (not shown) and perform the same processing as described above. An image signal similar to that obtained when the fluorescent lamps 13 to 15 are turned on exclusively can be obtained.

〔Effect of the invention〕

As explained above, according to the present invention, some or all of the light sources can be turned on for a relatively long period of time, so even light sources with poor photoresponsiveness can be used, increasing the degree of freedom in selecting the light source. In addition, it is possible to perform good image reading using a light source with spectral characteristics suitable for each color image reading device.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram of a reading unit of a conventional color image reading device, FIG. 2 is a timing diagram for explaining the reading operation of this device, and FIGS. 3 to 5 show an embodiment of the present invention. Figure 3 is a schematic configuration diagram of a color image reading device, Figure 4 is a timing diagram showing the principle of reading operation, Figure 5 is a block diagram of a color conversion circuit, and Figure 6 is for explanation purposes. FIG. 3 is a timing chart for explaining the principle of a reading operation in a modified example of the present invention. 11... Manuscript, 13.14.15... Fluorescent light (light source), 17.
...Image sensor (photoelectric conversion element), 31-3
3...Lighting device, 34...Lighting control circuit, 38...Color conversion circuit, 39.40...Line memory (image signal delay means). Applicant Fuji Zero/7x Co., Ltd. Agent Patent Attorney Umeo Yamauchi Figure 1 Figure 2 Figure 3 Figure 4 Figure 6 Figure 5 Figure 38/

Claims (1)

[Claims] 11. A plurality of light sources for irradiating a document with mutually different spectral characteristics, a photoelectric conversion element that receives light reflected from the document by these light sources and photoelectrically converts it as an image signal, and each reading line. light source lighting control means for lighting some of the light sources redundantly in a specific main scan for a predetermined number of main scans repeated for a given number of times, and changing the combination of the redundant light sources for each main scan; 14) color conversion means for calculating the two or more types of image signals obtained in accordance with the main scanning position and creating color-separated image signals for the reading line; Image reading device. 2. Claim No. 2, characterized in that it comprises an image signal delay means for processing image signals for each main scan obtained at different main scan timings for the same reading line on the same time axis. The color image reading device according to item 1.